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Home My WebLink AboutPriority Development Project Storm Water Quality Management PlanPDP SWQMP Template Date: January 2016 PDP SWQMP PRIORITY DEVELOPMENT PROJECT (PDP) STORM WATER QUALITY MANAGEMENT PLAN FOR Bonita Glen 570-131-11, 570-010-10, 570-140-48 & 570-140-51 Insert Permit Application Number Insert Drawing Number ENGINEER OF WORK: ___________________________________________________________________________________ Giovanni Posillico REC 66332 Expires 6-30-20 PREPARED FOR: SILVERGATE DEVELOPMENT, LLC 4980 N Harbor Drive, Suite 203 San Diego, CA 92106 (619) 625-1260 PREPARED BY: LATITUDE 33 PLANNING AND ENGINEERING 9968 Hibert Street, 2nd Floor San Diego, CA, 92131 (858) 751-0633 DATE: 06/15/2018 ________________________________________________________________________ Approved By: City of Chula Vista Date: Page intentionally left blank for double-sided printing TABLE OF CONTENTS Acronym Sheet Preparer's Certification Page Submittal Record Project Vicinity Map Storm Water Requirements Applicability Checklist (Intake Form) FORM I-3B Site Information Checklist for PDPs FORM I-4 Source Control BMP Checklist for All Development Projects FORM I-5 Site Design BMP Checklist for All Development Projects FORM I-6 Summary of PDP Structural BMPs Attachment 1: Backup for PDP Pollutant Control BMPs Attachment 1a: DMA Exhibit Attachment 1b: Tabular Summary of DMAs and Design Capture Volume Calculations Attachment 1c: Harvest and Use Feasibility Screening (when applicable) Attachment 1d: Categorization of Infiltration Feasibility Condition (when applicable) Attachment 1e: Pollutant Control BMP Design Worksheets / Calculations Attachment 2: Backup for PDP Hydromodification Control Measures Attachment 2a: Hydromodification Management Exhibit Attachment 2b: Management of Critical Coarse Sediment Yield Areas Attachment 2c: Geomorphic Assessment of Receiving Channels Attachment 2d: Flow Control Facility Design Attachment 3: Structural BMP Maintenance Plan Attachment 3a: B Structural BMP Maintenance Thresholds and Actions Attachment 3b: Draft Maintenance Agreement (when applicable) Attachment 4: Copy of Plan Sheets Showing Permanent Storm Water BMPs ACRONYMS APN Assessor's Parcel Number BMP Best Management Practice HMP Hydromodification Management Plan HSG Hydrologic Soil Group MS4 Municipal Separate Storm Sewer System N/A Not Applicable NRCS Natural Resources Conservation Service PDP Priority Development Project PE Professional Engineer SC Source Control SD Site Design SDRWQCB San Diego Regional Water Quality Control Board SIC Standard Industrial Classification SWQMP Storm Water Quality Management Plan CERTIFICATION PAGE Project Name: Bonita Glen Permit Application Number: Insert Application # I hereby declare that I am the Engineer in Responsible Charge of design of storm water best management practices (BMPs) for this project, and that I have exercised responsible charge over the design of the BMPs as defined in Section 6703 of the Business and Professions Code, and that the design is consistent with the PDP requirements of the City of Chula Vista BMP Design Manual, which is based on the requirements of the San Diego Regional Water Quality Control Board Order No. R9-2013-0001 as amended by R9-2015-0001 and R9-2015-0100 (MS4 Permit). I have read and understand that the City Engineer has adopted minimum requirements for managing urban runoff, including storm water, from land development activities, as described in the BMP Design Manual. I certify that this PDP SWQMP has been completed to the best of my ability and accurately reflects the project being proposed and the applicable BMPs proposed to minimize the potentially negative impacts of this project's land development activities on water quality. I understand and acknowledge that the plan check review of this PDP SWQMP by the City Engineer is confined to a review and does not relieve me, as the Engineer in Responsible Charge of design of storm water BMPs for this project, of my responsibilities for project design. ________________________________________________________ Engineer of Work's Signature, PE Number & Expiration Date ________________________________________________________ Print Name ________________________________________________________ Company ____________________________ Date Engineer's Seal Page intentionally left blank for double-sided printing SUBMITTAL RECORD Use this Table to keep a record of submittals of this PDP SWQMP. Each time the PDP SWQMP is re-submitted, provide the date and status of the project. In column 4 summarize the changes that have been made or indicate if response to plancheck comments is included. When applicable, insert response to plancheck comments behind this page. Submittal Number Date Project Status Summary of Changes 1 12/13/2017 ܈ Preliminary Design/ Planning/ CEQA ܆ Final Design Initial Submittal 2 04/11/2018 ܈ Preliminary Design/ Planning/ CEQA ܆ Final Design Second Submittal 3 06/25/2018 ܈ Preliminary Design/ Planning/ CEQA ܆ Final Design Third Submittal 4 Click here to enter a date. ܆Preliminary Design/ Planning/ CEQA ܆Final Design Click here to enter text. Page intentionally left blank for double-sided printing PROJECT VICINITY MAP Project Name: Bonita Glen Permit Application Number: Insert Permit Application Number Page intentionally left blank for double-sided printing Complete and attach Storm Water Requirements Applicability Checklist (Intake Form) included in Appendix A.1 Storm Water Requirements Applicability Checklist (Intake Form)for All Permit Applications Public Works Department - Storm Water Management Section April 2016 Project Information Project Address:Project Application Number: Project Name:APN(s) Brief Description of Work Proposed: Owner/Contact Information Name of Person Completing this Form: Role: Property Owner Contractor Architect Engineer Other ____________________ Email:Phone: Signature:Date Completed: Answer each section below, starting with Section 1 and progressing through each section.Additional information for determining the requirements is found in the Chula Vista BMP Design Manual available on the City’s website at http://www.chulavistaca.gov/departments/public-works/services/storm-water-pollution- prevention/documents-and-reports. SECTION 1: Storm Water BMP Requirements Does the project consist of one or both of the following: x Repair or improvements to an existing building or structure that donot alter the size such as: tenant improvements, interior remodeling, electrical work, fire alarm, fire sprinkler system, HVAC work, Gas, plumbing, etc. x Routine maintenance activities such as: roof or exterior structure surface replacement; resurfacing existing roadways and parking lots including digouts, slurry seal, overlay and restriping; repair damaged sidewalks or pedestrian ramps on existing roads without expanding the impervious footprint; routine replacement of damaged pavement, trenching and resurfacing associated with utility work (i.e. sewer, water, gas or electrical laterals, etc.) and pot holing or geotechnical investigation borings. Yes Project is NOT Subject to Permanent Storm Water BMP requirements, BUT IS subject to Construction BMP requirements. Review & sign “Construction Storm Water BMP Certification Statement”on page 2. No Continue to Section 2, page3. 8 Vista Dr., Chula Vista, CA 91910 Bonita Glen 570-131-11, 570-010-10, 570-140-48 Develop land for a site containing 130 townhomes/stacked flat units Casey Jumanan 858-875-1744 Print Form melanie.foronda@latitude33.com and parking City of Chula Vista Storm Water Applicability Checklist (Intake Form) Page 2 of 5 (April 2016) Construction Storm Water BMP Certification Statement The following stormwater quality protection measures are required by City Chula Vista Municipal Code Chapter 14.20 and the City’s Jurisdictional Runoff Management Program. 1. All applicable construction BMPs and non-stormwater discharge BMPs shall be installed and maintained for the duration of the project in accordance with the Appendix K “Construction BMP Standards” of the Chula Vista BMP Design Manual. 2.Erosion control BMPs shall be implemented for all portions of the project area in which no work has been done or is planned to be done over a period of 14 or more days. All onsite drainage pathways that convey concentrated flows shall be stabilized to prevent erosion. 3. Run-on from areas outside the project area shall be diverted around work areas to the extent feasible. Run-on that cannot be diverted shall be managed using appropriate erosion and sediment control BMPs. 4.Sediment control BMPs shall be implemented, including providing fiber rolls, gravel bags, or other equally effective BMPs around the perimeter of the project to prevent transport of soil and sediment offsite. Any sediment tracked onto offsite paved areas shall be removed via sweeping at least daily. 5.Trash and other construction wastes shall be placed in a designated area at least daily and shall be disposed of in accordance with applicable requirements. 6. Materials shall be stored to avoid being transported in storm water runoff and non-storm water discharges. Concrete washout shall be directed to a washout area and shall not be washed out to the ground. 7.Stockpiles and other sources of pollutants shall be covered when the chance of rain within the next 48 hours is at least 50%. I certify that the stormwater quality protection measures listed above will be implemented at the project described on Intake Form. I understand that failure to implement these measures may result in monetary penalties or other enforcement actions. This certification is signed under penalty of perjury and does not require notarization. Name: __________________________________________ Title: ________________________________ Signature: _________________________________________ Date: __________________________ Melanie Foronda Design Engineer 6/19/18 City of Chula Vista Storm Water Applicability Checklist (Intake Form) Page 3 of 5 (April 2016) Section 2: Determine if Project is a Standard Project or Priority Development Project 1.The project is (select one): New Development Redevelopment (is the creation and/or replacement of impervious surface on an already developed site) 2. Is the project in any of the following categories, (a) through (j)? a.New development that creates 10,000 square feet or more of impervious surfaces (collectively over the entire project site). This includes commercial, industrial, residential, mixed-use, and public development projects on public or private land. Yes No b.Redevelopment project that creates and/or replaces 5,000 square feet or more of impervious surface (collectively over the entire project site on an existing site of 10,000 square feet or more of impervious surfaces). This includes commercial, industrial, residential, mixed-use, and public developm ent projects on public or private land. Yes No c. New development or redevelopment of a restaurant that creates and/or replaces 5,000 square feet or more of impervious surface (collectively over the entire project site). This category is defined as a facility that sells prepared foods and drinks for consumption, including stationary lunch counters and refreshment stands selling prepared foods and drinks for immediate consumption (Standard Industrial Classification Code 5812). Yes No d.New development or redevelopment of hillside that creates and/or replaces 5,000 square feet or more of impervious surface (collectively over the entire project site). This category includes development on any natural slope that is twenty-five percent or greater. Yes No e.New development or redevelopment of parking lot that creates and/or replaces 5,000 square feet or more of impervious surface (collectively over the entire project site).This category is defined as a land area or facility for the temporary parking or storage of motor vehicles used personally, for business, or for commerce. Yes No f. New development or redevelopment of Streets, roads, highways, freeways, and driveways that creates and/or replaces 5,000 square feet or more of impervious surface (collectively over the entire project site).This category is defined as any paved impervious surface used for the transportation of automobiles, trucks, motorcycles, and other vehicles Yes No g. New development or redevelopment project that creates and/or replaces 2,500 square feet or more of impervious surface (collectively over the entire project site), discharging directly to an Environmentally Sensitive Area (ESA). “Discharging directly to” includes flow that is conveyed overland a distance of 200 feet or less from the project to t he ESA, or conveyed in a pipe or open channel any distance as an isolated flow from the project to the ESA (i.e. not commingled with flows from adjacent lands). Yes No h. New development or redevelopment project of automotive repair shops that creates and/or replaces 5,000 square feet or more of impervious surface. This category is defined as a facility that is categorized in any one of the following Standard Industrial Classification (SIC) codes: 5013, 5014, 5541, 7532-7534, or 7536-7539. Yes No i.New development or redevelopment projects of retail gasoline outlets that creates and/or replaces 5,000 square feet or more of impervious surface or its projected Average Daily Traffic (ADT) of 100 or more vehicles per day. Yes No j.New development or redevelopment that result in the disturbance of one or more acres of land and are expected to generate pollutants post construction. Yes No City of Chula Vista Storm Water Applicability Checklist (Intake Form) Page 4 of 5 (April 2016) The project is (select one): If “No” is checked for every category in Section 2, project is “Standard Development Project”. Site design and source control BMP requirements apply. Complete and submit Standard SWQMP (refer to Chapter 4 & Appendix E of the BMP Design Manual for guidance). Continue to Section 4. If “Yes” is checked for ANY category in Section 2,project is “Priority Development Project (PDP)”. Complete below, if applicable, and continue to Section 3. Complete for PDP Redevelopment Projects ONLY: The total existing (pre-project) impervious area at the project site is: ___________ ft 2 (A) The total proposed newly created or replaced impervious area is __________ ft 2 (B) Percent impervious surface created or replaced (B/A)*100: _______% The percent impervious surface created or replaced is (select one based on the above calculation): less than or equal to fifty percent (50%) –only new impervious areas are considered a PDP OR greater than fifty percent (50%) –the entire project site is considered a PDP Continue to Section 3 Section 3: Determine if project is PDP Exempt 1.Does the project ONLY include new or retrofit sidewalk, bicycle lane or trails that: x Are designed and constructed to direct storm water runoff to adjacent vegetated areas, or other non-erodible permeable areas? Or; x Are designed and constructed to be hydraulically disconnected from paved streets or roads? Or; x Are designed and constructed with permeable pavements or surfaces in accordance with USEPA Green Streets guidance? Yes. Project is PDP Exempt. Complete and submit Standard SWQMP (refer to Chapter 4 of the BMP Design Manual for guidance).Continue to Section 4. No. Next question 2.Does the project ONLY include retrofitting or redevelopment of existing paved alleys, streets or roads designed and constructed in accordance with the Green Streets standards? Yes. Project is PDP Exempt. Complete and submit Standard SWQMP (refer to Chapter 4 of the BMP Design Manual for guidance).Continue to Section 4. No. Project is PDP. Site design, source control and structural pollutant control BMPs apply. Complete and submit PDP SWQMP (refer to Chapters 4, 5 & 6 of the BMP Design Manual for guidance). Continue to Section 4. 1,690 131,613 7,788 City of Chula Vista Storm Water Applicability Checklist (Intake Form) Page 5 of 5 (April 2016) SECTION 4: Construction Storm Water BMP Requirements: All construction sites are required to implement construction BMPs in accordance with the performance standards in the BMP Design Manual. Some sites are additionally required to obtain coverage under the State Construction General Permit (CGP), which is administered by the State Water Resource Control Board. 1.Does the project include Building/Grading/Construction permits proposing less than 5,000 square feet of ground disturbance and has less than 5-foot elevation change over the entire project area? Yes; review & sign Construction Storm Water Certification Statement, skip questions 2-4 No; next question 2. Does the project propose construction or demolition activity, including but not limited to, clearing grading, grubbing, excavation, or other activity that results in ground disturbance of less than one acre and more than 5,000 square feet? Yes. complete & submit Construction Storm Water Pollution Control Plan (CSWPCP), skip questions 3-4 No; next question 3.Does the project results in disturbance of an acre or more of total land area and are considered regular maintenance projects performed to maintain original line and grade, hydraulic capacity, or original purpose of the facility? (Projects such as sewer/storm drain/utility replacement) Yes. complete & submit Construction Storm Water Pollution Control Plan (CSWPCP), skip question 4 No; next question 4.Is the project proposing land disturbance greater than or equal to one acre OR the project is part of a larger common plan of development disturbing 1 acre or more? Yes; Storm Water Pollution Prevention Plan (SWPPP) is required. Refer to online CASQA or Caltrans Template. Visit the SWRCB web site at http://www.waterboards.ca.gov/water_issues/programs/stormwater/construction.shtml . Note: for Projects that result in disturbance of one to five acres of total land area and can demonstrate that there will be no adverse water quality impacts by applying for a Construction Rainfall Erosivity Waiver, may be allowed to submit a CSWPCP in lieu of a SWPPP. Page intentionally left blank for double-sided printing Site Information Checklist For PDPs Form I-3B (for PDPs) Project Summary Information Project Name Bonita Glen Project Address 8 Vista Drive Chula Vista, CA 91910 Assessor's Parcel Number(s) (APN(s)) 570-131-11, 570-010-10, 570-140-48, & 570-140-51 Permit Application Number Click here to enter text. Project Hydrologic Unit Select One: ܆ Pueblo San Diego (908) ܈ Sweetwater (909) ܆ Otay (910) ܆ Tijuana (911) Project Watershed (Complete Hydrologic Unit, Area, and Subarea Name with Numeric Identifier) San Diego Bay, Sweetwater, 909 Parcel Area (total area of Assessor's Parcel(s) associated with the project) 4.7 Acres (206,257 Square Feet) Area to be Disturbed by the Project (Project Area) 5.7 Acres (249,998 Square Feet) Project Proposed Impervious Area (subset of Project Area) 3.7 Acres (164,325 Square Feet) Project Proposed Pervious Area (subset of Project Area) 2.0 Acres (85,673 Square Feet) Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the Project. This may be less than the Parcel Area. The proposed increase or decrease in impervious area in the proposed condition as compared to the pre-project condition. 47 % Form I-3B Page 2 of 10 Description of Existing Site Condition and Drainage Patterns Current Status of the Site (select all that apply): ܆ Existing development ܆ Previously graded but not built out ܆ Demolition completed without new construction ܆ Agricultural or other non-impervious use ܈ Vacant, undeveloped/natural Description / Additional Information: Click here to enter text Existing Land Cover Includes (select all that apply): ܈ Vegetative Cover ܆ Non-Vegetated Pervious Areas ܈ Impervious Areas Description / Additional Information: Click here to enter text. Underlying Soil belongs to Hydrologic Soil Group (select all that apply): ܆ NRCS Type A ܆ NRCS Type B ܆ NRCS Type C ܈ NRCS Type D Approximate Depth to Groundwater (GW): ܆ GW Depth < 5 feet ܆ 5 feet < GW Depth < 10 feet ܆ 10 feet < GW Depth < 20 feet ܈ GW Depth > 20 feet Existing Natural Hydrologic Features (select all that apply): ܈ Watercourses ܆ Seeps ܆ Springs ܆ Wetlands ܆ None Description / Additional Information: Click here to enter text Form I-3B Page 3 of 10 Description of Existing Site Topography and Drainage How is storm water runoff conveyed from the site? At a minimum, this description should answer: (1) whether existing drainage conveyance is natural or urban; (2) Is runoff from offsite conveyed through the site? if yes, quantify all offsite drainage areas, design flows, and locations where offsite flows enter the project site, and summarize how such flows are conveyed through the site; (3) Provide details regarding existing project site drainage conveyance network, including any existing storm drains, concrete channels, swales, detention facilities, storm water treatment facilities, natural or constructed channels; and (4) Identify all discharge locations from the existing project site along with a summary of conveyance system size and capacity for each of the discharge locations. Provide summary of the pre-project drainage areas and design flows to each of the existing runoff discharge locations. Description / Additional Information: The project area is composed of one basin with one ultimate collection point located at the northwest corner of the site. Generally, the site drains from the southeast to the northwest, with an existing catch basin located at the end of Vista Drive, draining through a concrete ditch to an open channel stream that ultimately drains to an existing inlet at the northwest corner of the site. There are (5) five sub-catchments within the overall watershed that generally flow from south to north and west and the northern most basin which flows east to west. Form I-3B Page 4 of 10 Description of Proposed Site Development and Drainage Patterns Project Description / Proposed Land Use and/or Activities: Bonita Glen is a development project that proposes to construct 130 townhomes/flatstacked units with on-site surface and garage parking. List/describe proposed impervious features of the project (e.g., buildings, roadways, parking lots, courtyards, athletic courts, other impervious features): The proposed impervious areas include sidewalks, buildings, patios, a pool area, courtyards, and surface parking. List/describe proposed pervious features of the project (e.g., landscape areas): The proposed pervious areas consist of biofiltration basins, trees, and landscaped areas. Does the project include grading and changes to site topography? ܈ Yes ܆ No Description / Additional Information: The Project proposes to change the existing topography by adding parking lots, curb & gutters, and building to the site. The existing drainage direction flows towards the west into the existing creek. The proposed development will direct runoff in multiple directions and eventually discharge into the existing drainage system. Form I-3B Page 5 of 10 Does the project include changes to site drainage (e.g., installation of new storm water conveyance systems)? ܈ Yes ܆ No If yes, provide details regarding the proposed project site drainage conveyance network, including storm drains, concrete channels, swales, detention facilities, storm water treatment facilities, natural or constructed channels, and the method for conveying offsite flows through or around the proposed project site. Identify all discharge locations from the proposed project site along with a summary of the conveyance system size and capacity for each of the discharge locations. Provide a summary of pre- and post-project drainage areas and design flows to each of the runoff discharge locations. Reference the drainage study for detailed calculations. Describe proposed site drainage patterns:: The current existing drainage currently flows over the natural site into a stream in the middle of the site. Drainage that comes from the eastern part of the site, flows from the streets to an existing catch basin, which ultimately flows down to a concrete ditch and outlets into the above said stream. All of the flow then outlets as untreated runoff to POC ‘A’. The project proposes to reroute the existing drainage into treatable areas, biofiltration basins, and outlet through an existing storm drain on the western side of the project. The proposed project footprint generates a footprint of approximately 47% impervious area. In order to mitigate the impervious area, the project proposes 3 biofiltration basins that are projected to treat 84% of the runoff. The other 16% will drain naturally into the stream in the middle of the site. There is no proposed hydromodification due to runoff discharging at the Sweetwater River through existing conveyances. Form I-3B Page 6 of 10 Identify whether any of the following features, activities, and/or pollutant source areas will be present (select all that apply): ܈ On-site storm drain inlets ܆ Interior floor drains and elevator shaft sump pumps ܈ Interior parking garages ܆ Need for future indoor & structural pest control ܈ Landscape/Outdoor Pesticide Use ܈ Pools, spas, ponds, decorative fountains, and other water features ܆ Food service ܆ Refuse areas ܆ Industrial processes ܆ Outdoor storage of equipment or materials ܆ Vehicle and Equipment Cleaning ܆ Vehicle/Equipment Repair and Maintenance ܆ Fuel Dispensing Areas ܆ Loading Docks ܆ Fire Sprinkler Test Water ܆ Miscellaneous Drain or Wash Water ܈ Plazas, sidewalks, and parking lots Description / Additional Information: Click here to enter text Form I-3B Page 7 of 10 Identification and Narrative of Receiving Water and Pollutants of Concern Describe flow path of storm water from the project site discharge location(s), through urban storm conveyance systems as applicable, to receiving creeks, rivers, and lagoons as applicable, and ultimate discharge to the Pacific Ocean (or bay, lagoon, lake or reservoir, as applicable): Runoff from the development flows into Sweetwater rive approximately 0.2 miles from the project site. Approximately 3.5 miles downstream from the project site, runoff confluences with the San Diego Bay to the Pacific Ocean at the San Diego Shoreline. List any 303(d) impaired water bodies within the path of storm water from the project site to the Pacific Ocean (or bay, lagoon, lake or reservoir, as applicable), identify the pollutant(s)/stressor(s) causing impairment, and identify any TMDLs and/or Highest Priority Pollutants from the WQIP for the impaired water bodies: 303(d) Impaired Water Body Pollutant(s)/Stressor(s) TMDLs/ WQIP Highest Priority Pollutant Sweetwater River, Lower Enterococcus Click here to enter text. Click here to enter text Fecal Coliform Click here to enter text. Click here to enter text Nitrogen, Phosphorous, Selenium, Total Dissolved Solids, Toxicity Click here to enter text. Identification of Project Site Pollutants* *Identification of project site pollutants is only required if flow-thru treatment BMPs are implemented onsite in lieu of retention or biofiltration BMPs (note the project must also participate in an alternative compliance program unless prior lawful approval to meet earlier PDP requirements is demonstrated) Identify pollutants anticipated from the project site based on all proposed use(s) of the site (see BMP Design Manual Appendix B.6): Pollutant Not Applicable to the Project Site Anticipated from the Project Site Also a Receiving Water Pollutant of Concern Sediment ܆ ܆ ܆ Nutrients ܆ ܆ ܆ Heavy Metals ܆ ܆ ܆ Organic Compounds ܆ ܆ ܆ Trash & Debris ܆ ܆ ܆ Oxygen Demanding Substances ܆ ܆ ܆ Oil & Grease ܆ ܆ ܆ Bacteria & Viruses ܆ ܆ ܆ Pesticides ܆ ܆ ܆ Form I-3B Page 8 of 10 Hydromodification Management Requirements Do hydromodification management requirements apply (see Section 1.6 of the BMP Design Manual)? ܆ Yes, hydromodification management flow control structural BMPs required. ܆ No, the project will discharge runoff directly to existing underground storm drains discharging directly to water storage reservoirs, lakes, enclosed embayments, or the Pacific Ocean. ܆ No, the project will discharge runoff directly to conveyance channels whose bed and bank are concrete-lined all the way from the point of discharge to water storage reservoirs, lakes, enclosed embayments, or the Pacific Ocean. ܈ No, the project will discharge runoff directly to an area identified as appropriate for an exemption by the WMAA for the watershed in which the project resides. Description / Additional Information (to be provided if a 'No' answer has been selected above): The discharge with enter and existing storm drain conveyance to Sweeter water River, just north of the project which flows to the Pacific Ocean. Critical Coarse Sediment Yield Areas* *This Section only required if hydromodification management requirements apply Based on the maps provided within the WMAA, do potential critical coarse sediment yield areas exist within the project drainage boundaries? ܈ Yes ܆ No, No critical coarse sediment yield areas to be protected based on WMAA maps If yes, have any of the optional analyses presented in Section 6.2 of the BMP Design Manual been performed? ܈ 6.2.1 Verification of Geomorphic Landscape Units (GLUs) Onsite ܈ 6.2.2 Downstream Systems Sensitivity to Coarse Sediment ܈ 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite ܆ No optional analyses performed, the project will avoid critical coarse sediment yield areas identified based on WMAA maps If optional analyses were performed, what is the final result? ܆ No critical coarse sediment yield areas to be protected based on verification of GLUs onsite ܆ Critical coarse sediment yield areas exist but additional analysis has determined that protection is not required. Documentation attached in Attachment 2.b of the SWQMP. ܈ Critical coarse sediment yield areas exist and require protection. The project will implement management measures described in Sections 6.2.4 and 6.2.5 as applicable, and the areas are identified on the SWQMP Exhibit. Discussion / Additional Information: Click here to enter text Form I-3B Page 9 of 10 Flow Control for Post-Project Runoff* *This Section only required if hydromodification management requirements apply List and describe point(s) of compliance (POCs) for flow control for hydromodification management (see Section 6.3.1). For each POC, provide a POC identification name or number correlating to the project's HMP Exhibit and a receiving channel identification name or number correlating to the project's HMP Exhibit. Click here to enter text Has a geomorphic assessment been performed for the receiving channel(s)? ܆ No, the low flow threshold is 0.1Q2 (default low flow threshold) ܆ Yes, the result is the low flow threshold is 0.1Q2 ܆ Yes, the result is the low flow threshold is 0.3Q2 ܆ Yes, the result is the low flow threshold is 0.5Q2 If a geomorphic assessment has been performed, provide title, date, and preparer: Click here to enter text Discussion / Additional Information: (optional) Click here to enter text Form I-3B Page 10 of 10 Other Site Requirements and Constraints When applicable, list other site requirements or constraints that will influence storm water management design, such as zoning requirements including setbacks and open space, or local codes governing minimum street width, sidewalk construction, allowable pavement types, and drainage requirements. Click here to enter text Optional Additional Information or Continuation of Previous Sections As Needed This space provided for additional information or continuation of information from previous sections as needed. Click here to enter text Source Control BMP Checklist for All Development Projects (Standard Projects and PDPs) Form I-4 Project Identification Project Name: Bonita Glen Permit Application Number: Insert Permit Application # Source Control BMPs All development projects must implement source control BMPs SC-1 through SC-6 where applicable and feasible. See Chapter 4 and Appendix E of the manual for information to implement source control BMPs shown in this checklist. Answer each category below pursuant to the following. x "Yes" means the project will implement the source control BMP as described in Chapter 4 and/or Appendix E of the manual. Discussion / justification is not required. x "No" means the BMP is applicable to the project but it is not feasible to implement. Discussion / justification must be provided. x "N/A" means the BMP is not applicable at the project site because the project does not include the feature that is addressed by the BMP (e.g., the project has no outdoor materials storage areas). Discussion / justification may be provided. Source Control Requirement Applied? SC-1 Prevention of Illicit Discharges into the MS4 ܈Yes ܆No ܆N/A Discussion / justification if SC-1 not implemented: Click here to enter text SC-2 Storm Drain Stenciling or Signage ܈Yes ܆No ܆N/A Discussion / justification if SC-2 not implemented: Click here to enter text SC-3 Protect Outdoor Materials Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal ܆Yes ܆No ܈N/A Discussion / justification if SC-3 not implemented: Click here to enter text SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall, Run-On, Runoff, and Wind Dispersal ܆Yes ܆No ܈N/A Discussion / justification if SC-4 not implemented: Click here to enter text Form I-4 Page 2 of 2 Source Control Requirement Applied? SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal ܈Yes ܆No ܆N/A Discussion / justification if SC-5 not implemented: Click here to enter text SC-6 Additional BMPs Based on Potential Sources of Runoff Pollutants (must answer for each source listed below) ܆ Onsite storm drain inlets ܆ Interior floor drains and elevator shaft sump pumps ܆ Interior parking garages ܆ Need for future indoor & structural pest control ܆ Landscape/outdoor pesticide use ܆ Pools, spas, ponds, decorative fountains, and other water features ܆ Food service ܆ Refuse areas ܆ Industrial processes ܆ Outdoor storage of equipment or materials ܆ Vehicle and equipment cleaning ܆ Vehicle/equipment repair and maintenance ܆ Fuel dispensing areas ܆ Loading docks ܆ Fire sprinkler test water ܆ Miscellaneous drain or wash water ܆ Plazas, sidewalks, and parking lots ܈Yes ܆Yes ܈Yes ܆Yes ܈Yes ܈Yes ܆Yes ܆Yes ܆Yes ܆Yes ܆Yes ܆Yes ܆Yes ܆Yes ܆Yes ܈Yes ܈Yes ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆No ܆N/A ܈N/A ܆N/A ܈N/A ܆N/A ܆N/A ܈N/A ܈N/A ܈N/A ܈N/A ܈N/A ܈N/A ܈N/A ܈N/A ܈N/A ܆N/A ܆N/A Discussion / justification if SC-6 not implemented. Clearly identify which sources of runoff pollutants are discussed. Justification must be provided for all "No" answers shown above. Click here to enter text Site Design BMP Checklist for All Development Projects (Standard Projects and PDPs) Form I-5 Project Identification Project Name: Bonita Glen Permit Application Number: Insert Application # Site Design BMPs All development projects must implement site design BMPs SD-1 through SD-8 where applicable and feasible. See Chapter 4 and Appendix E of the manual for information to implement site design BMPs shown in this checklist. Answer each category below pursuant to the following. x "Yes" means the project will implement the site design BMP as described in Chapter 4 and/or Appendix E of the manual. Discussion / justification is not required. x "No" means the BMP is applicable to the project but it is not feasible to implement. Discussion / justification must be provided. x "N/A" means the BMP is not applicable at the project site because the project does not include the feature that is addressed by the BMP (e.g., the project site has no existing natural areas to conserve). Discussion / justification may be provided. Site Design Requirement Applied? SD-1 Maintain Natural Drainage Pathways and Hydrologic Features ܈Yes ܆No ܆N/A Discussion / justification if SD-1 not implemented: Click here to enter text SD-2 Conserve Natural Areas, Soils, and Vegetation ܈Yes ܆No ܆N/A Discussion / justification if SD-2 not implemented: Click here to enter text SD-3 Minimize Impervious Area ܈Yes ܆No ܆N/A Discussion / justification if SD-3 not implemented: Click here to enter text SD-4 Minimize Soil Compaction ܈Yes ܆No ܆N/A Discussion / justification if SD-4 not implemented: Click here to enter text Form I-5 Page 2 of 2 Site Design Requirement Applied? SD-5 Impervious Area Dispersion ܆Yes ܆No ܈N/A Discussion / justification if SD-5 not implemented: Click here to enter text SD-6 Runoff Collection ܆Yes ܆No ܈N/A Discussion / justification if SD-6 not implemented: Click here to enter text. SD-7 Landscaping with Native or Drought Tolerant Species ܆Yes ܆No ܈N/A Discussion / justification if SD-7 not implemented: Click here to enter text. SD-8 Harvesting and Using Precipitation ܆Yes ܈No ܆N/A Discussion / justification if SD-8 not implemented: Harvesting and using precipitation is not feasible. Summary of PDP Structural BMPs Form I-6 (For PDPs) Project Identification Project Name: Bonita Glen Permit Application Number: Insert Permit Application # PDP Structural BMPs All PDPs must implement structural BMPs for storm water pollutant control (see Chapter 5 of the manual). Selection of PDP structural BMPs for storm water pollutant control must be based on the selection process described in Chapter 5. PDPs subject to hydromodification management requirements must also implement structural BMPs for flow control for hydromodification management (see Chapter 6 of the manual). Both storm water pollutant control and flow control for hydromodification management can be achieved within the same structural BMP(s). PDP structural BMPs must be verified by the local jurisdiction at the completion of construction. This may include requiring the project owner or project owner's representative to certify construction of the structural BMPs (see Section 1.12 of the manual). PDP structural BMPs must be maintained into perpetuity, and the local jurisdiction must confirm the maintenance (see Section 7 of the manual). Use this form to provide narrative description of the general strategy for structural BMP implementation at the project site in the box below. Then complete the PDP structural BMP summary information sheet (page 3 of this form) for each structural BMP within the project (copy the BMP summary information page as many times as needed to provide summary information for each individual structural BMP). Describe the general strategy for structural BMP implementation at the site. This information must describe how the steps for selecting and designing storm water pollutant control BMPs presented in Section 5.1 of the manual were followed, and the results (type of BMPs selected). For projects requiring hydromodification flow control BMPs, indicate whether pollutant control and flow control BMPs are integrated or separate. Step 1 – The project includes a self-mitigating area in DMA 5 and DMA 4. Step 2 – Per the included Harvest and Use fesasibility screening Form I-7, the proposed project is considered to be infeasible for harvest and use. Step 3 – Biofiltration basins have been implemented to treat the majority of required onsite DCV. Biofiltration basins were chosen because of the low infiltration rates and the potential damaging of utilities, development infrastructure and building foundations due to mounded water during wet periods. (Continue on page 2 as necessary.) Form I-6 Page 2 of 8 (Page reserved for continuation of description of general strategy for structural BMP implementation at the site) (Continued from page 1) Form I-6 Page 3 of 8 (Copy as many as needed) Structural BMP Summary Information (Copy this page as needed to provide information for each individual proposed structural BMP) Structural BMP ID No.: 1 Construction Plan Sheet No.: Click here to enter text. Type of structural BMP: ܆ Retention by harvest and use (HU-1) ܆ Retention by infiltration basin (INF-1) ܆ Retention by bioretention (INF-2) ܆ Retention by permeable pavement (INF-3) ܆ Partial retention by biofiltration with partial retention (PR-1) ܈ Biofiltration (BF-1) ܆ Flow-thru treatment control with prior lawful approval to meet earlier PDP requirements (provide BMP type/description in discussion section below) ܆ Flow-thru treatment control included as pre-treatment/forebay for an onsite retention or biofiltration BMP (provide BMP type/description and indicate which onsite retention or biofiltration BMP it serves in discussion section below) ܆ Flow-thru treatment control with alternative compliance (provide BMP type/description in discussion section below) ܆ Detention pond or vault for hydromodification management ܆ Other (describe in discussion section below) Purpose: ܈ Pollutant control only ܆ Hydromodification control only ܆ Combined pollutant control and hydromodification control ܆ Pre-treatment/forebay for another structural BMP ܆ Other (describe in discussion section below) Who will certify construction of this BMP? Provide name and contact information for the party responsible to sign BMP verification forms if required by the City Engineer (See Section 1.12 of the manual) Giovanni Posillico RCE 66332 Latitude 33 Planning & Engineering 9968 Hibert Street 2nd Floor San Diego, CA 92131 (858)875-1735 Who will be the final owner of this BMP? Pathfinder Silvergate La Mesa, LLC Who will maintain this BMP into perpetuity? Pathfinder Silvergate La Mesa, LLC What is the funding mechanism for maintenance? Pathfinder Silvergate La Mesa, LLC Discussion (as needed): Form I-6 Page 4 of 8 (Copy as many as needed) Structural BMP ID No.: 1 Construction Plan Sheet No.: Click here to enter text. Discussion (as needed): BMP 1 is a biofiltration basin for pollutant control purposes. Form I-6 Page 5 of 8 (Copy as many as needed) Structural BMP Summary Information (Copy this page as needed to provide information for each individual proposed structural BMP) Structural BMP ID No.: 2 Construction Plan Sheet No.: Click here to enter text. Type of structural BMP: ܆ Retention by harvest and use (HU-1) ܆ Retention by infiltration basin (INF-1) ܆ Retention by bioretention (INF-2) ܆ Retention by permeable pavement (INF-3) ܆ Partial retention by biofiltration with partial retention (PR-1) ܈ Biofiltration (BF-1) ܆ Flow-thru treatment control with prior lawful approval to meet earlier PDP requirements (provide BMP type/description in discussion section below) ܆ Flow-thru treatment control included as pre-treatment/forebay for an onsite retention or biofiltration BMP (provide BMP type/description and indicate which onsite retention or biofiltration BMP it serves in discussion section below) ܆ Flow-thru treatment control with alternative compliance (provide BMP type/description in discussion section below) ܆ Detention pond or vault for hydromodification management ܆ Other (describe in discussion section below) Purpose: ܈ Pollutant control only ܆ Hydromodification control only ܆ Combined pollutant control and hydromodification control ܆ Pre-treatment/forebay for another structural BMP ܆ Other (describe in discussion section below) Who will certify construction of this BMP? Provide name and contact information for the party responsible to sign BMP verification forms if required by the City Engineer (See Section 1.12 of the manual) Giovanni Posillico RCE 66332 Latitude 33 Planning & Engineering 9968 Hibert Street 2nd Floor San Diego, CA 92131 (858)875-1735 Who will be the final owner of this BMP? Pathfinder Silvergate La Mesa, LLC Who will maintain this BMP into perpetuity? Pathfinder Silvergate La Mesa, LLC What is the funding mechanism for maintenance? Pathfinder Silvergate La Mesa, LLC Discussion (as needed): Form I-6 Page 6 of 8 (Copy as many as needed) Structural BMP ID No.: 2 Construction Plan Sheet No.: Click here to enter text. Discussion (as needed): BMP 2 is a biofiltration basin for pollutant control purposes. Form I-6 Page 7 of 8 (Copy as many as needed) Structural BMP Summary Information (Copy this page as needed to provide information for each individual proposed structural BMP) Structural BMP ID No.: 3 Construction Plan Sheet No.: Click here to enter text. Type of structural BMP: ܆ Retention by harvest and use (HU-1) ܆ Retention by infiltration basin (INF-1) ܆ Retention by bioretention (INF-2) ܆ Retention by permeable pavement (INF-3) ܆ Partial retention by biofiltration with partial retention (PR-1) ܈ Biofiltration (BF-1) ܆ Flow-thru treatment control with prior lawful approval to meet earlier PDP requirements (provide BMP type/description in discussion section below) ܆ Flow-thru treatment control included as pre-treatment/forebay for an onsite retention or biofiltration BMP (provide BMP type/description and indicate which onsite retention or biofiltration BMP it serves in discussion section below) ܆ Flow-thru treatment control with alternative compliance (provide BMP type/description in discussion section below) ܆ Detention pond or vault for hydromodification management ܆ Other (describe in discussion section below) Purpose: ܈ Pollutant control only ܆ Hydromodification control only ܆ Combined pollutant control and hydromodification control ܆ Pre-treatment/forebay for another structural BMP ܆ Other (describe in discussion section below) Who will certify construction of this BMP? Provide name and contact information for the party responsible to sign BMP verification forms if required by the City Engineer (See Section 1.12 of the manual) Giovanni Posillico RCE 66332 Latitude 33 Planning & Engineering 9968 Hibert Street 2nd Floor San Diego, CA 92131 (858)875-1735 Who will be the final owner of this BMP? Pathfinder Silvergate La Mesa, LLC Who will maintain this BMP into perpetuity? Pathfinder Silvergate La Mesa, LLC What is the funding mechanism for maintenance? Pathfinder Silvergate La Mesa, LLC Discussion (as needed): Form I-6 Page 8 of 8 (Copy as many as needed) Structural BMP ID No.: 3 Construction Plan Sheet No.: Click here to enter text. Discussion (as needed): BMP 3 is a biofiltration basin for pollutant control purposes. ATTACHMENT 1 BACKUP FOR PDP POLLUTANT CONTROL BMPS This is the cover sheet for Attachment 1. Page intentionally left blank for double-sided printing Indicate which items are included behind this cover sheet: Attachment Sequence Contents Checklist Attachment 1a DMA Exhibit (Required) See DMA Exhibit Checklist on the back of this Attachment cover sheet. ܈ Included Attachment 1b Tabular Summary of DMAs Showing DMA ID matching DMA Exhibit, DMA Area, and DMA Type (Required)* *Provide table in this Attachment OR on DMA Exhibit in Attachment 1a ܈ Included on DMA Exhibit in Attachment 1a ܆ Included as Attachment 1b, separate from DMA Exhibit Attachment 1c Form I-7, Harvest and Use Feasibility Screening Checklist (Required unless the entire project will use infiltration BMPs) Refer to Appendix B.3-1 of the BMP Design Manual to complete Form I-7. ܈ Included ܆ Not included because the entire project will use infiltration BMPs Attachment 1d Form I-8, Categorization of Infiltration Feasibility Condition (Required unless the project will use harvest and use BMPs) Refer to Appendices C and D of the BMP Design Manual to complete Form I-8. ܈ Included ܆ Not included because the entire project will use harvest and use BMPs Attachment 1e Pollutant Control BMP Design Worksheets / Calculations (Required) Refer to Appendices B and E of the BMP Design Manual for structural pollutant control BMP design guidelines ܈ Included Use this checklist to ensure the required information has been included on the DMA Exhib it: The DMA Exhibit must identify: ܆ Underlying hydrologic soil group ܆ Approximate depth to groundwater ܆ Existing natural hydrologic features (watercourses, seeps, springs, wetlands) ܆ Critical coarse sediment yield areas to be protected ܆ Existing topography and impervious areas ܆ Existing and proposed site drainage network and connections to drainage offsite ܆ Proposed demolition ܆ Proposed grading ܆ Proposed impervious features ܆ Proposed design features and surface treatments used to minimize imperviousness ܆ Drainage management area (DMA) boundaries, DMA ID numbers, and DMA areas (square footage or acreage), and DMA type (i.e., drains to BMP, self-retaining, or self-mitigating) ܆ Potential pollutant source areas and corresponding required source controls (see Chapter 4, Appendix E.1, and Form I-3B) ܆ Structural BMPs (identify location, type of BMP, and size/detail) Harvest and Use Feasibility Screening Form I-7 1. Is there a demand for harvested water (check all that apply) at the project site that is reliably present during the wet season? Toilet and urinal flushing Landscape Irrigation Other: ______________ 2. If there is a demand; estimate the anticipated average wet season demand over a period of 36 hours. Guidance for planning level demand calculations for toilet/urinal flushing and landscape irrigation is provided in Section B.3.2. Total/Urinal: 170 Units x 9.3 gallons/day = 1581 gallons 211.35 cubic feet Landscape Irrigation: 390 x 2.8 acres = 1092 gallons 145.98 cubic feet Total Demand: 161.62 cubic feet + 145.98 cubic feet = 307.6 cubic feet 3. Calculate the DCV using worksheet B-2.1. Per worksheet B-2.1, the DCV is 5912 cubic feet. 3a. Is the 36-hour demand greater than or equal to the DCV? Yes / No 3b. Is the 36-hour demand greater than 0.25 DCV but less than the full DCV? Yes / No 3c. Is the 36-hour demand less than 0.25DCV? Yes Harvest and use appears to be feasible. Conduct more detailed evaluation and sizing calculations to confirm that DCV can be used at an adequate rate to meet drawdown criteria. Harvest and use may be feasible. Conduct more detailed evaluation and sizing calculations to determine feasibility. Harvest and use may only be able to be used for a portion of the site, or (optionally) the storage may need to be upsized to meet long term capture targets while draining in longer than 36 hours. Harvest and use is considered to be infeasible. Is harvest and use feasible based on further evaluation? Yes, refer to appendix E to select and size harvest and use BMPs No, select alternate BMPs Appendix I: Forms and Checklists BMP Design Manual-Appendices December 2015 I-5 Categorization of Infiltration Feasibility Condition Form I-8 Part 1 - Full Infiltration Feasibility Screening Criteria Would infiltration of the full design volume be feasible from a physical perspective without any undesirable consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No 1 Is the estimated reliable infiltration rate below proposed facility locations greater than 0.5 inches per hour? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: 7KHLQILOWUDWLRQUDWHRIWKHH[LVWLQJVRLOVIRUORFDWLRQV3WKURXJK3EDVHGRQWKHRQVLWHLQILOWUDWLRQVWXG\ZDVFDOFXODWHGWR EHOHVVWKDQLQFKHVSHUKRXU3 3 3 DQG3 LQFKHVSHUKRXUDIWHUDSSO\LQJDPLQLPXP IDFWRURIVDIHW\)RI) 2 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. Provide basis: 1R6HH&ULWHULRQ ; ; Appendix I: Forms and Checklists BMP Design Manual-Appendices December 2015 I-6 Form I-8 Page 2 of 4 Criteria Screening Question Yes No 3 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of groundwater contamination (shallow water table, storm water pollutants or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: :DWHUFRQWDPLQDWLRQZDVQRWHYDOXDWHGE\129$6HUYLFHV,QF129$ 4 Can infiltration greater than 0.5 inches per hour be allowed without causing potential water balance issues such as change of seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: 7KHSRWHQWLDOIRUZDWHUEDODQFHZDVQRWHYDOXDWHGE\129$6HUYLFH,QF129$ Part 1 Result* If all answers to rows 1 - 4 are “Yes” a full infiltration design is potentially feasible. The feasibility screening category is Full Infiltration If any answer from row 1-4 is “No”, infiltration may be possible to some extent but would not generally be feasible or desirable to achieve a “full infiltration” design. Proceed to Part 2 *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by the City Engineer to substantiate findings 3URFHHGWR 3DUW Appendix I: Forms and Checklists BMP Design Manual-Appendices December 2015 I-7 Form I-8 Page 3 of 4 Part 2 – Partial Infiltration vs. No Infiltration Feasibility Screening Criteria Would infiltration of water in any appreciable amount be physically feasible without any negative consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No 5 Do soil and geologic conditions allow for infiltration in any appreciable rate or volume? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: 7KHLQILOWUDWLRQUDWHRIWKHH[LVWLQJVRLOVIRUORFDWLRQ3WKURXJK3EDVHGRQWKHRQVLWHLQILOWUDWLRQVWXG\ZDV FDOFXODWHGWREHOHVVWKDQLQFKHVSHUKRXU3 3 3 DQG3 LQFKHVSHUKRXU DIWHUDSSO\LQJDPLQLPXPIDFWRURIVDIHW\)RI) ,QILOWUDWLRQUDWHVRIOHVVWKDQLQFKHVSHUKRXUDQGJUHDWHU WKDQLQFKHVSHUKRXULPSO\WKDWJHRORJLFFRQGLWLRQVDOORZIRUSDUWLDOLQILOWUDWLRQ,QILOWUDWLRQUDWHVDUHQRW JUHDWHUWKDQ 7KHVHZLGHVSUHDGYHU\ORZWRQRSHUPHDELOLW\VRLODQGJHRORJLFFRQGLWLRQVGRQRWDOORZIRULQILOWUDWLRQLQDQ\ DSSUHFLDEOHUDWHRUYROXPH 6 Can Infiltration in any appreciable quantity be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. Provide basis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ppendix I: Forms and Checklists BMP Design Manual-Appendices December 2015 I-8 Form I-8 Page 4 of 4 Criteria Screening Question Yes No 7 Can Infiltration in any appreciable quantity be allowed without posing significant risk for groundwater related concerns (shallow water table, storm water pollutants or other factors)? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: :DWHUFRQWDPLQDWLRQZDVQRWHYDOXDWHGE\129$6HUYLFHV,QF129$ 8 Can infiltration be allowed without violating downstream water rights? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: 7KHSRWHQWLDOIRUZDWHUEDODQFHZDVQRWHYDOXDWHGE\129$6HUYLFH,QF129$ Part 2 Result* If all answers from row 5-8 are yes then partial infiltration design is potentially feasible. The feasibility screening category is Partial Infiltration. If any answer from row 5-8 is no, then infiltration of any volume is considered to be infeasible within the drainage area. The feasibility screening category is No Infiltration. *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by the City Engineer to substantiate findings. 1R,QILOWUDWLRQ 185th percentile 24-hr storm depth from Figure B.1-1 d=0.53 inches 2 Area tributary to BMP (s) A=0.35 acres 3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1)C=0.17 unitless 4 Trees Credit Volume TCV= cubic-feet 5 Rain barrels Credit Volume RCV= cubic-feet 6 Calculate DCV = (3630 x C x d x A) – TCV - RCV DCV=116 cubic-feet Design Capture Volume Worksheet B.2-1 Worksheet B.2-1 DCV DMA 1 1 Remaining DCV after implementing retention BMPs 116 cubic- feet 2 Infiltration rate from Worksheet D.5-1 if partial infiltration is feasible 0 in/hr. 3 Allowable drawdown time for aggregate storage below the underdrain 36 hours 4 Depth of runoff that can be infiltrated [Line 2 x Line 3]0 inches 5 Aggregate pore space 0.40 in/in 6 Required depth of gravel below the underdrain [Line 4/ Line 5]0.00 inches 7 Assumed surface area of the biofiltration BMP 44.3 sq-ft 8 Media retained pore storage 0.1 in/in 9 Volume retained by BMP [[Line 4 + (Line 12 x Line 8)]/12] x Line 7 6.6 cubic- feet 10 DCV that requires biofiltration [Line 1 – Line 9]109.4 cubic- feet 11 Surface Ponding [6 inch minimum, 12 inch maximum]6 inches 12 Media Thickness [18 inches minimum], also add mulch layer thickness to this line for sizing calculations 18 inches 13 Aggregate Storage above underdrain invert (12 inches typical) – use 0 inches for sizing if the aggregate is not over the entire bottom surface area 12 inches 14 Freely drained pore storage 0.2 in/in 15 Media filtration rate to be used for sizing (5 in/hr. with no outlet control; if the filtration rate is controlled by the outlet use the outlet controlled rate which will be less than 5 in/hr.) 5.0 in/hr. 16 Allowable Routing Time for sizing 6 hours 17 Depth filtered during storm [ Line 15 x Line 16]30 inches 18 Depth of Detention Storage [Line 11 + (Line 12 x Line 14) + (Line 13 x Line 5)]14 inches 19 Total Depth Treated [Line 17 + Line 18]44 inches Note: Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to the required biofiltration footprint (either Line 21 or Line 23) Simple Sizing Method for Biofiltration BMPs Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs Worksheet B.5-1 (Page 1 of 2) BMP Parameters Partial Retention Baseline Calculations 20 164.0 cubic- feet 21 44.3 sq-ft 22 82.0 cubic- feet 23 68.3 sq-ft 24 15351.68 sq-ft 25 0.17 26 0.03 27 78.3 sq-ft 28 78.3 sq-ft 29 0.05728448 unitless 30 0.375 unitless 31 Yes No Required Footprint [Line 20/ Line 19] x 12 Required Storage (surface + pores) Volume [0.75 x Line 10] Required Footprint [Line 22/ Line 18] x 12 1. Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to the required biofiltration footprint (either Line 21 or Line 23) Simple Sizing Method for Biofiltration BMPs Calculate the fraction of DCV retained in the BMP [Line 9/Line 1] Minimum required fraction of DCV retained for partial infiltration condition Is the retained DCV ≥ 0.375? If the answer is no increase the footprint sizing factor in Line 26 until the answer is yes for this criterion. Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs (continued) Note: 2. The DCV fraction of 0.375 is based on a 40% average annual percent capture and a 36-hour drawdown time. 3. The increase in footprint for volume reduction can be optimized using the approach presented in Appendix B.5.2. The optimized footprint cannot be smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2. 4. If the proposed biofiltration BMP footprint is smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2, but satisfies Option 1 or Option 2 sizing, it is considered a compact biofiltration BMP and may be allowed at the discretion of the City Engineer, if it meets the requirements in Appendix F. Check for Volume Reduction [Not applicable for No Infiltration Condition] Worksheet B.5-1 (Page 2 of 2) Footprint of the BMP Area draining to the BMP Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) Minimum BMP Footprint [Line 24 x Line 25 x Line 26] BMP Footprint Sizing Factor (Default 0.03 or an alternative minimum footprint sizing factor from Worksheet B.5-2, Line 11) Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 27) Option 1 – Biofilter 1.5 times the DCV Option 2 - Store 0.75 of remaining DCV in pores and ponding Required biofiltered volume [1.5 x Line 10] 185th percentile 24-hr storm depth from Figure B.1-1 d=0.53 inches 2 Area tributary to BMP (s) A=0.26 acres 3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1)C=0.52 unitless 4 Trees Credit Volume TCV= cubic-feet 5 Rain barrels Credit Volume RCV= cubic-feet 6 Calculate DCV = (3630 x C x d x A) – TCV - RCV DCV=260 cubic-feet Design Capture Volume Worksheet B.2-1 Worksheet B.2-1 DCV DMA 2 20 367.6 cubic- feet 21 99.4 sq-ft 22 183.8 cubic- feet 23 153.2 sq-ft 24 11177.67 sq-ft 25 0.52 26 0.03 27 174.4 sq-ft 28 174.4 sq-ft 29 0.05734615 unitless 30 0.375 unitless 31 Yes No Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs (continued) Note: 2. The DCV fraction of 0.375 is based on a 40% average annual percent capture and a 36-hour drawdown time. 3. The increase in footprint for volume reduction can be optimized using the approach presented in Appendix B.5.2. The optimized footprint cannot be smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2. 4. If the proposed biofiltration BMP footprint is smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2, but satisfies Option 1 or Option 2 sizing, it is considered a compact biofiltration BMP and may be allowed at the discretion of the City Engineer, if it meets the requirements in Appendix F. Check for Volume Reduction [Not applicable for No Infiltration Condition] Worksheet B.5-1 (Page 2 of 2) Footprint of the BMP Area draining to the BMP Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) Minimum BMP Footprint [Line 24 x Line 25 x Line 26] BMP Footprint Sizing Factor (Default 0.03 or an alternative minimum footprint sizing factor from Worksheet B.5-2, Line 11) Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 27) Option 1 – Biofilter 1.5 times the DCV Option 2 - Store 0.75 of remaining DCV in pores and ponding Required biofiltered volume [1.5 x Line 10] Required Footprint [Line 20/ Line 19] x 12 Required Storage (surface + pores) Volume [0.75 x Line 10] Required Footprint [Line 22/ Line 18] x 12 1. Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to the required biofiltration footprint (either Line 21 or Line 23) Simple Sizing Method for Biofiltration BMPs Calculate the fraction of DCV retained in the BMP [Line 9/Line 1] Minimum required fraction of DCV retained for partial infiltration condition Is the retained DCV ≥ 0.375? If the answer is no increase the footprint sizing factor in Line 26 until the answer is yes for this criterion. 185th percentile 24-hr storm depth from Figure B.1-1 d=0.53 inches 2 Area tributary to BMP (s) A=0.82 acres 3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1)C=0.70 unitless 4 Trees Credit Volume TCV= cubic-feet 5 Rain barrels Credit Volume RCV= cubic-feet 6 Calculate DCV = (3630 x C x d x A) – TCV - RCV DCV=1111 cubic-feet Design Capture Volume Worksheet B.2-1 Worksheet B.2-1 DCV DMA 3 20 1571.0 cubic- feet 21 424.6 sq-ft 22 785.5 cubic- feet 23 654.6 sq-ft 24 35661.97 sq-ft 25 0.7 26 0.03 27 748.9 sq-ft 28 748.9 sq-ft 29 0.05732673 unitless 30 0.375 unitless 31 Yes No Required Footprint [Line 20/ Line 19] x 12 Required Storage (surface + pores) Volume [0.75 x Line 10] Required Footprint [Line 22/ Line 18] x 12 1. Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to the required biofiltration footprint (either Line 21 or Line 23) Simple Sizing Method for Biofiltration BMPs Calculate the fraction of DCV retained in the BMP [Line 9/Line 1] Minimum required fraction of DCV retained for partial infiltration condition Is the retained DCV ≥ 0.375? If the answer is no increase the footprint sizing factor in Line 26 until the answer is yes for this criterion. Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs (continued) Note: 2. The DCV fraction of 0.375 is based on a 40% average annual percent capture and a 36-hour drawdown time. 3. The increase in footprint for volume reduction can be optimized using the approach presented in Appendix B.5.2. The optimized footprint cannot be smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2. 4. If the proposed biofiltration BMP footprint is smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2, but satisfies Option 1 or Option 2 sizing, it is considered a compact biofiltration BMP and may be allowed at the discretion of the City Engineer, if it meets the requirements in Appendix F. Check for Volume Reduction [Not applicable for No Infiltration Condition] Worksheet B.5-1 (Page 2 of 2) Footprint of the BMP Area draining to the BMP Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) Minimum BMP Footprint [Line 24 x Line 25 x Line 26] BMP Footprint Sizing Factor (Default 0.03 or an alternative minimum footprint sizing factor from Worksheet B.5-2, Line 11) Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 27) Option 1 – Biofilter 1.5 times the DCV Option 2 - Store 0.75 of remaining DCV in pores and ponding Required biofiltered volume [1.5 x Line 10] 185th percentile 24-hr storm depth from Figure B.1-1 d=0.53 inches 2 Area tributary to BMP (s) A=0.74 acres 3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1)C=0.32 unitless 4 Trees Credit Volume TCV= cubic-feet 5 Rain barrels Credit Volume RCV= cubic-feet 6 Calculate DCV = (3630 x C x d x A) – TCV - RCV DCV=458 cubic-feet Design Capture Volume Worksheet B.2-1 Worksheet B.2-1 DCV DMA 5 20 647.6 cubic- feet 21 175.0 sq-ft 22 323.8 cubic- feet 23 269.8 sq-ft 24 32414.22 sq-ft 25 0.74 26 0.03 27 719.6 sq-ft 28 719.6 sq-ft 29 0.05731441 unitless 30 0.375 unitless 31 Yes No Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs (continued) Note: 2. The DCV fraction of 0.375 is based on a 40% average annual percent capture and a 36-hour drawdown time. 3. The increase in footprint for volume reduction can be optimized using the approach presented in Appendix B.5.2. The optimized footprint cannot be smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2. 4. If the proposed biofiltration BMP footprint is smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2, but satisfies Option 1 or Option 2 sizing, it is considered a compact biofiltration BMP and may be allowed at the discretion of the City Engineer, if it meets the requirements in Appendix F. Check for Volume Reduction [Not applicable for No Infiltration Condition] Worksheet B.5-1 (Page 2 of 2) Footprint of the BMP Area draining to the BMP Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) Minimum BMP Footprint [Line 24 x Line 25 x Line 26] BMP Footprint Sizing Factor (Default 0.03 or an alternative minimum footprint sizing factor from Worksheet B.5-2, Line 11) Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 27) Option 1 – Biofilter 1.5 times the DCV Option 2 - Store 0.75 of remaining DCV in pores and ponding Required biofiltered volume [1.5 x Line 10] Required Footprint [Line 20/ Line 19] x 12 Required Storage (surface + pores) Volume [0.75 x Line 10] Required Footprint [Line 22/ Line 18] x 12 1. Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to the required biofiltration footprint (either Line 21 or Line 23) Simple Sizing Method for Biofiltration BMPs Calculate the fraction of DCV retained in the BMP [Line 9/Line 1] Minimum required fraction of DCV retained for partial infiltration condition Is the retained DCV ≥ 0.375? If the answer is no increase the footprint sizing factor in Line 26 until the answer is yes for this criterion. 185th percentile 24-hr storm depth from Figure B.1-1 d=0.53 inches 2 Area tributary to BMP (s) A=1.11 acres 3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1)C=0.75 unitless 4 Trees Credit Volume TCV= cubic-feet 5 Rain barrels Credit Volume RCV= cubic-feet 6 Calculate DCV = (3630 x C x d x A) – TCV - RCV DCV=1601 cubic-feet Design Capture Volume Worksheet B.2-1 Worksheet B.2-1 DCV DMA 6 20 2263.8 cubic- feet 21 611.9 sq-ft 22 1131.9 cubic- feet 23 943.3 sq-ft 24 48647.73 sq-ft 25 0.75 26 0.03 27 1094.6 sq-ft 28 1094.6 sq-ft 29 0.05732042 unitless 30 0.375 unitless 31 Yes No Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs (continued) Note: 2. The DCV fraction of 0.375 is based on a 40% average annual percent capture and a 36-hour drawdown time. 3. The increase in footprint for volume reduction can be optimized using the approach presented in Appendix B.5.2. The optimized footprint cannot be smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2. 4. If the proposed biofiltration BMP footprint is smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2, but satisfies Option 1 or Option 2 sizing, it is considered a compact biofiltration BMP and may be allowed at the discretion of the City Engineer, if it meets the requirements in Appendix F. Check for Volume Reduction [Not applicable for No Infiltration Condition] Worksheet B.5-1 (Page 2 of 2) Footprint of the BMP Area draining to the BMP Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) Minimum BMP Footprint [Line 24 x Line 25 x Line 26] BMP Footprint Sizing Factor (Default 0.03 or an alternative minimum footprint sizing factor from Worksheet B.5-2, Line 11) Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 27) Option 1 – Biofilter 1.5 times the DCV Option 2 - Store 0.75 of remaining DCV in pores and ponding Required biofiltered volume [1.5 x Line 10] Required Footprint [Line 20/ Line 19] x 12 Required Storage (surface + pores) Volume [0.75 x Line 10] Required Footprint [Line 22/ Line 18] x 12 1. Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to the required biofiltration footprint (either Line 21 or Line 23) Simple Sizing Method for Biofiltration BMPs Calculate the fraction of DCV retained in the BMP [Line 9/Line 1] Minimum required fraction of DCV retained for partial infiltration condition Is the retained DCV ≥ 0.375? If the answer is no increase the footprint sizing factor in Line 26 until the answer is yes for this criterion. 185th percentile 24-hr storm depth from Figure B.1-1 d=0.53 inches 2 Area tributary to BMP (s) A=2.33 acres 3 Area weighted runoff factor (estimate using Appendix B.1.1 and B.2.1)C=0.72 unitless 4 Trees Credit Volume TCV= cubic-feet 5 Rain barrels Credit Volume RCV= cubic-feet 6 Calculate DCV = (3630 x C x d x A) – TCV - RCV DCV=3216 cubic-feet Design Capture Volume Worksheet B.2-1 Worksheet B.2-1 DCV DMA 7 20 4547.5 cubic- feet 21 1229.0 sq-ft 22 2273.7 cubic- feet 23 1894.8 sq-ft 24 103696.84 sq-ft 25 0.72 26 0.03 27 2239.9 sq-ft 28 2239.9 sq-ft 29 0.05732276 unitless 30 0.375 unitless 31 Yes No Worksheet B.5-1: Simple Sizing Method for Biofiltration BMPs (continued) Note: 2. The DCV fraction of 0.375 is based on a 40% average annual percent capture and a 36-hour drawdown time. 3. The increase in footprint for volume reduction can be optimized using the approach presented in Appendix B.5.2. The optimized footprint cannot be smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2. 4. If the proposed biofiltration BMP footprint is smaller than the alternative minimum footprint sizing factor from Worksheet B.5-2, but satisfies Option 1 or Option 2 sizing, it is considered a compact biofiltration BMP and may be allowed at the discretion of the City Engineer, if it meets the requirements in Appendix F. Check for Volume Reduction [Not applicable for No Infiltration Condition] Worksheet B.5-1 (Page 2 of 2) Footprint of the BMP Area draining to the BMP Adjusted Runoff Factor for drainage area (Refer to Appendix B.1 and B.2) Minimum BMP Footprint [Line 24 x Line 25 x Line 26] BMP Footprint Sizing Factor (Default 0.03 or an alternative minimum footprint sizing factor from Worksheet B.5-2, Line 11) Footprint of the BMP = Maximum(Minimum(Line 21, Line 23), Line 27) Option 1 – Biofilter 1.5 times the DCV Option 2 - Store 0.75 of remaining DCV in pores and ponding Required biofiltered volume [1.5 x Line 10] Required Footprint [Line 20/ Line 19] x 12 Required Storage (surface + pores) Volume [0.75 x Line 10] Required Footprint [Line 22/ Line 18] x 12 1. Line 7 is used to estimate the amount of volume retained by the BMP. Update assumed surface area in Line 7 until its equivalent to the required biofiltration footprint (either Line 21 or Line 23) Simple Sizing Method for Biofiltration BMPs Calculate the fraction of DCV retained in the BMP [Line 9/Line 1] Minimum required fraction of DCV retained for partial infiltration condition Is the retained DCV ≥ 0.375? If the answer is no increase the footprint sizing factor in Line 26 until the answer is yes for this criterion. ATTACHMENT 2 BACKUP FOR PDP HYDROMODIFICATION CONTROL MEASURES This is the cover sheet for Attachment 2. Page intentionally left blank for double-sided printing ܈ Mark this box if this attachment is empty because the project is exempt from PDP hydromodification management requirements. Indicate which items are included behind this cover sheet: Attachment Sequence Contents Checklist Attachment 2a Hydromodification Management Exhibit (Required) ܆ Included See Hydromodification Management Exhibit Checklist on the back of this Attachment cover sheet. Attachment 2b Management of Critical Coarse Sediment Yield Areas (WMAA Exhibit is required, additional analyses are optional) See Section 6.2 of the BMP Design Manual. ܆ Exhibit showing project drainage boundaries marked on WMAA Critical Coarse Sediment Yield Area Map (Required) Optional analyses for Critical Coarse Sediment Yield Area Determination ܆ 6.2.1 Verification of Geomorphic Landscape Units Onsite ܆ 6.2.2 Downstream Systems Sensitivity to Coarse Sediment ܆ 6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite Attachment 2c Geomorphic Assessment of Receiving Channels (Optional) See Section 6.3.4 of the BMP Design Manual. ܆ Not performed ܆ Included ܆ Submitted as separate stand-alone document Attachment 2d Flow Control Facility Design, including Structural BMP Drawdown Calculations and Overflow Design Summary (Required) See Chapter 6 and Appendix G of the BMP Design Manual ܆ Included ܆ Submitted as separate stand-alone document Attachment 2e Vector Control Plan (Required when structural BMPs will not drain in 96 hours) ܆ Included ܆ Not required because BMPs will drain in less than 96 hours Use this checklist to ensure the required information has been included on the Hydromodification Management Exhibit: The Hydromodification Management Exhibit must identify: ܆ Underlying hydrologic soil group ܆ Approximate depth to groundwater ܆ Existing natural hydrologic features (watercourses, seeps, springs, wetlands) ܆ Critical coarse sediment yield areas to be protected ܆ Existing topography ܆ Existing and proposed site drainage network and connections to drainage offsite ܆ Proposed grading ܆ Proposed impervious features ܆ Proposed design features and surface treatments used to minimize imperviousness ܆ Point(s) of Compliance (POC) for Hydromodification Management ܆ Existing and proposed drainage boundary and drainage area to each POC (when necessary, create separate exhibits for pre-development and post-project conditions) ܆ Structural BMPs for hydromodification management (identify location, type of BMP, and size/detail) ATTACHMENT 3 Structural BMP Maintenance Information This is the cover sheet for Attachment 3. Page intentionally left blank for double-sided printing Indicate which items are included behind this cover sheet: Attachment Sequence Contents Checklist Attachment 3a Structural BMP Maintenance Thresholds and Actions (Required) ܈ Included See Structural BMP Maintenance Information Checklist on the back of this Attachment cover sheet. Attachment 3b Draft Maintenance Agreement (when applicable) ܆ Included ܆ Not Applicable Use this checklist to ensure the required information has been included in the Structural BMP Maintenance Information Attachment: ܆܆ Preliminary Design / Planning / CEQA level submittal: Attachment 3a must identify: ܆ Typical maintenance indicators and actions for proposed structural BMP(s) based on Section 7.7 of the BMP Design Manual Attachment 3b is not required for preliminary design / planning / CEQA level submittal. ܆ Final Design level submittal: Attachment 3a must identify: ܆ Specific maintenance indicators and actions for proposed structural BMP(s). This shall be based on Section 7.7 of the BMP Design Manual and enhanced to reflect actual proposed components of the structural BMP(s) ܆ How to access the structural BMP(s) to inspect and perform maintenance ܆ Features that are provided to facilitate inspection (e.g., observation ports, cleanouts, silt posts, or other features that allow the inspector to view necessary components of the structural BMP and compare to maintenance thresholds) ܆ Manufacturer and part number for proprietary parts of structural BMP(s) when applicable ܆ Maintenance thresholds specific to the structural BMP(s), with a location-specific frame of reference (e.g., level of accumulated materials that triggers removal of the materials, to be identified based on viewing marks on silt posts or measured with a survey rod with respect to a fixed benchmark within the BMP) ܆ Recommended equipment to perform maintenance ܆ When applicable, necessary special training or certification requirements for inspection and maintenance personnel such as confined space entry or hazardous waste management Attachment 3b: For private entity operation and maintenance, Attachment 3b shall include a draft maintenance agreement in the local jurisdiction's standard format (PDP applicant to contact the City Engineer to obtain the current maintenance agreement forms). Page intentionally left blank for double-sided printing ^dZhdhZ>DWD/EdEE&KZ/K&/>dZd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opy of Plan Sheets Showing Permanent Storm Water BMPs This is the cover sheet for Attachment 4. Page intentionally left blank for double-sided printing Use this checklist to ensure the required information has been included on the plans: The plans must identify: ܆ Structural BMP(s) with ID numbers matching Form I-6 Summary of PDP Structural BMPs ܆ The grading and drainage design shown on the plans must be consistent with the delineation of DMAs shown on the DMA exhibit ܆ Details and specifications for construction of structural BMP(s) ܆ Signage indicating the location and boundary of structural BMP(s) as required by the [City Engineer] ܆ How to access the structural BMP(s) to inspect and perform maintenance ܆ Features that are provided to facilitate inspection (e.g., observation ports, cleanouts, silt posts, or other features that allow the inspector to view necessary components of the structural BMP and compare to maintenance thresholds) ܆ Manufacturer and part number for proprietary parts of structural BMP(s) when applicable ܆ Maintenance thresholds specific to the structural BMP(s), with a location-specific frame of reference (e.g., level of accumulated materials that triggers removal of the materials, to be identified based on viewing marks on silt posts or measured with a survey rod with respect to a fixed benchmark within the BMP) ܆ Recommended equipment to perform maintenance ܆ When applicable, necessary special training or certification requirements for inspection and maintenance personnel such as confined space entry or hazardous waste management ܆ Include landscaping plan sheets showing vegetation requirements for vegetated structural BMP(s) ܆ All BMPs must be fully dimensioned on the plans ܆ When proprietary BMPs are used, site-specific cross section with outflow, inflow, and model number shall be provided. Photocopies of general brochures are not acceptable. Project TH E P I C T O R I A L A N D G R A P H I C E X P R E S S I O N S D I S P L A Y E D W I T H T H I S W O R K AR E C O P Y R I G H T E D U N D E R T H E L A W S O F T H E U N I T E D S T A T E S , T I T L E 1 7 , U. S . C O D E . U N D E R S E C T I O N 1 0 6 O F T H E C O P Y R I G H T A C T , T H E A R C H I T E C T S H A L L M A I N T A I N T H E E X C L U S I V E R I G H T O F T H E R E P R O D U C T I O N , D I S P L AY O R A N Y D E R I V A T I O N O F T H I S W O R K . 10/12/17 Preliminary Review 12/13/17 Design Review 04/12/18 DR Resubmittal Bo n i t a G l e n R d , C h u l a V i s t a , C A 9 1 9 1 0 Ia n G i l l , S i l v e r g a t e D e v e l o p m e n t 16124 Bo n i t a G l e n A p a r t m e n t s GRADING AND STORM DRAIN SHEET C2 Page intentionally left blank for double-sided printing ATTACHMENT 5 Copy of Project's Drainage Report PRELIMINARY DRAINAGE STUDY WESLEY PALMS RETIREMENT COMMUNITY SAN DIEGO, CA 92109 (TENTATIVE MAP NO. _____) Original Date: March 9, 2012 Revised Date: TBD Prepared For: FRONT PORCH COMMUNITIES AND SERVICES 303 North Glenoaks Blvd., Suite 1000 Burbank, California 91502 Prepared By: LATITUDE 33 PLANNING AND ENGINEERING 5355 Mira Sorrento Place, Suite 650 San Diego, California 92121 (858) 751 - 0633 PRELIMINARY DRAINAGE STUDY BONITA GLEN BONITA GLEN DR. CHULA VISTA, CA 91910 2018 PREPARED BY: LATITUDE 33 PLANNING & ENGINEERING PREPARED FOR: PATHFINDER SILVERGATE LA MESA, LLC JOB NUMBER: 1522.00 DRAINAGE STUDY BONITA GLEN BONITA GLEN DR. CHULA VISTA, CA 91910 Prepared For: PATHFINDER SILVERGATE LA MESA, LLC 4980 N Harbor Drive Suite 203 San Diego, California 92106 Prepared By: LATITUDE 33 PLANNING AND ENGINEERING 9968 Hibert Street, 2nd Floor San Diego, California 92131 (858) 751 - 0633 __________________________________ Giovanni Posillico, PE Date RCE 66332 Expires 6-30-20 TABLE OF CONTENTS PAGE I. PURPOSE 1 II. PROJECT DESCRIPTION 1 III. METHODOLOGY 3 IV. EXISTING DRAINAGE CONDITION 5 V. PROPOSED DRAINAGE CONDITION 6 VI. DISCUSSION 7 VII. CONCLUSIONS 8 LIST OF FIGURES FIGURE 1 VICINITY MAP 1 FIGURE 2 EXISTING AERIAL 2 FIGURE 3 PROPOSED SITE PLAN 3 LIST OF TABLES TABLE 1 EXISTING HYDROLOGY SUMMARY 5 TABLE 2 PROPOSED HYDROLOGY SUMMARY 9 LIST OF APPENDICES APPENDIX A DRAINAGE MANUAL REFERENCE MATERIAL APPENDIX B EXISTING HYDROLOGY MAP AND CALCULATIONS APPENDIX C PROPOSED HYDROLOGY MAP AND CALCULATIONS APPENDIX D REFERENCE DRAWINGS Preliminary Drainage Study Bonita Glen Bonita Glen Dr., Chula Vista, CA 91910 1 I. PURPOSE The purpose of this Preliminary Drainage Study is to evaluate the existing and proposed drainage conditions (i.e. anticipated runoff flows) for the development of the Bonita Glen development located at Bonita Glen Dr., in the City of Chula Vista, California. This technical document has been prepared to identify any potential hydrologic impacts as a result of the development. Final staff approval and acceptance is required prior to final issuance of a Grading Permit. II. PROJECT DESCRIPTION PROJECT LOCATION The project site is located southwest of Interstate 805, north of H Street, and south of E Street. More particularly, the site is comprised of 3 lots legally described as a Portion of Lots 1, 2, and 3 of Map No. 2207, in the City of Chula Vista, County of San Diego, and State of California, filed in the Office of the County Recorder of San Diego County, June 30, 1936 and a Portion of Parcel B of Parcel Map No. 85, in the City of Chula Vista, County of San Diego, and State of California, filed in the Office of the County Recorder of San Diego County, December 30, 1968. The designated Assessor’s Parcel Numbers (APNs) are 570-131-11, 570-010-10, 570-140-48 & 570-140-51. Refer to the vicinity map below. FIGURE 1 – VICINITY MAP Preliminary Drainage Study Bonita Glen Bonita Glen Dr., Chula Vista, CA 91910 2 BACKGROUND The proposed project is located northeast of the Pont Bonita Apartments and Townhomes and north of Bonita Glen Dr. The project is composed of 4 parcels and is non-developed land. The adjacent property to the north is an inn, La Quinta Inn. Ac cess to the site is via Bonita Glen Dr. to the Southwest and from Vista Dr. to the north. The project is southwest of the Interstate 805 and an existing drainage channel, Sweetwater River. FIGURE 2 – EXISTING AERIAL PROPOSED PROJECT DESCRIPTION Silvergate Development, LC, is seeking approval to construct 170 townhome/stacked flat units with associated structure/surface parking. The proposed development will be served by connecting to existing public infrastructure (storm drain, water and sewer) within the adjacent street (Bonita Glen Drive). Refer to the proposed site plan below. Preliminary Drainage Study Bonita Glen Bonita Glen Dr., Chula Vista, CA 91910 3 FIGURE 3 – PROPOSED SITE PLAN III. METHODOLOGY The estimate of both the existing and proposed drainage flows has been performed in conformance with the County of San Diego Drainage Design Manual (2005 Edition), which the City of Chula Vista defers to. In this drainage study, all basins analyzed are less than one square mile. Therefore, the Rational Method from the County Hydrology Manual was utilized to calculate storm runoff for a 100-year frequency storm. Existing pipe hydraulic analysis is based on Manning’s equation and the criteria contained in the County Drainage Manual. Other criteria are described on the following page; Preliminary Drainage Study Bonita Glen Bonita Glen Dr., Chula Vista, CA 91910 4 x A weighted “C” factor based on table 3-1 of the County Hydrology Manual was used based on the following assumptions: o The proposed site is High Density Residential (HDR) o Type D soil per the soils report is used o The site is close to the HDR 43 DU/AC (C=0.79) [170 DU/4.8 AC = 35.42 DU/AC] x The existing site is made up of natural terrain. A “C” factor of 0.35 per Undisturbed Natural Terrain is used for all existing basins. Where topographic was available, a more accurate “C” factor was compiled based on ratios of impervious vs. pervious. x “C” factors vary between basins. A weighted “C” value will be used for each basin based on the ratio of impervious to pervious areas. x Intensity values were calculated using Rainfall Intensity-Duration-Frequency Curves for the County of San Diego according to the chart in Figure 3-1 of the County Hydrology Manual. A P6 of 2.5in was used for both the 50 and 100-year rainfall events. Additionally, P6/P24 was within the 45 to 65% threshold for both storm events (2.5/4.0 for 50yr and 2.5/5.0 for 100yr). x Initial travel time values were computed using the Overland Time of Flow Nomograph (Figure 3-3 in the County Hydrology Manual). x Figure 3-6, “Gutter and Roadway Discharge - Velocity Chart” and Manning’s Equation were used to determine the flow velocity for concentrated flows in curb and gutters, drainage channels and conduits. Travel times were then determined by dividing the flow distance by the velocity of flow. x Final times of concentration values for each basin were calculated by adding the initial and final travel times. A minimum five minute ToC is assumed where computed travel time is less than five minutes. x 100-year design storm interval was used in analyzing the hydrologic flows. Charts and tables noted above can be found in the County Hydrology Manual. The rational method module of the Autodesk Storm and Sanitary Analysis (SSA) was used to perform the hydrologic analysis. The analysis represents the basins represented via a Junction-Link model. Junctions and Links were modeled to represent the existing onsite creek and determine the maximum HGL downstream. Refer to Exhibits 1 and 2 included in this report that delineates the drainage basin boundaries and junctions. Printed results are included in Appendix ‘A’ and ‘B’ for reference. Preliminary Drainage Study Bonita Glen Bonita Glen Dr., Chula Vista, CA 91910 5 IV. EXISTING DRAINAGE CONDITION The project area is a 4.8-acre site composed of four drainage basins. Generally, the site drains from the southeast to the northwest corner of the property either by sheet flow or an existing storm drain system. The site receives off-site drainage from the east which drains to the northwest corner via surface flow. Additionally, the existing creek that runs through the project site receives off-site flow from a drainage basin to the south. This additional flow to the creek adds a Q100 flowrate of 51.3 cfs as analyzed by REC Consultants per “Technical Memorandum: Hydrologic & Hydraulic Analysis for Bonita Glen Creek”, dated January 25, 2018. Per the City of Chula Vista Master Plan, a peak flow of 66 cfs was analyzed in this drainage study. The report will be analyzed using a Q100 of 66 cfs for worst case scenario. The result of this additional flow causes the creek to flood in existing conditions. There is one (1) point of compliance in the northwest corner of the site as shown on the ‘Existing Hydrology Map’ contained with Appendix ‘D’. Basin E.01 Runoff generated from this 2.60-acre basin, including 0.58 acres of offsite flow, sheet flows from the east to the northwest. A portion of this basin flows west then north. The drainage flows to the drainage ditch on in the north of the site. Basin E.02 Runoff from this 1.54-acre basin, is conveyed from the south of the property towards the northwest. The water sheet flows across the property until it hits the existing open channel near the center of the site. Basin E.03 Runoff from this 1.14-acre basin is conveyed from the southwest of the property to the northwest. The water sheet flows across the property until it enters an existing open channel near the center of the site that runs through the property to an existing inlet. Basin E.04 Runoff off from this 0.30-acre basin sheet flows from the north towards the southwest where it enters an existing open channel near the center of the site. The flow from these points then enters a storm drain inlet that connects to the public storm drain system offsite. Preliminary Drainage Study Bonita Glen Bonita Glen Dr., Chula Vista, CA 91910 6 Refer to the table below for a summary of existing flow estimates analyzed in this report. Table No. 1 – Existing Hydrology Summary POC AREA (AC) RUNOFF 'C' Q 50-YR (CFS) Q 100-YR (CFS) ‘A’ 5.58 0.45 55.11 55.11 Note: The ‘C’ factor used to determine runoff was determined on a basin by basin analysis of pervious vs. impervious area. The ‘C’ factor was determined using Storm and Sanitary Analysis. V. PROPOSED DRAINAGE CONDITION The proposed improvements include the construction of six (6) apartment buildings, surface parking, streets, landscape areas and onsite accessible sidewalks. The proposed project area lies within the limits of the existing drainage basins previously mentioned above and will maintain existing drainage patterns. The site’s runoff will be directed to the exiting storm drain system in Bonita Glen Road, which the runoff will travel to the neighboring Sweetwater River. Basin P.01 This 0.35-acre basin sheet flows from the southeast to then northwest to the onsite proposed biofiltration basin. Once through the biofiltration basin, the water will be conveyed to the existing public storm drain system (POC ‘A’) that runs in Bonita Glen Dr. Basin P.02 This 0.26-acre basin sheet flows from the south to the north where it enters a proposed biofiltration basin via a curb cut. Once through the biofiltration basin, the water enters a proposed catch basin and proposed storm drain system and will be conveyed to the existing storm drain system on Bonita Glen Dr. Basin P.03 This 0.82-acre basin sheet flows from the south to the north where it enters a proposed biofiltration basin via curb cut. Once through the biofiltration basin, the water enters a proposed catch basin and proposed storm drain system and will be conveyed to the existing storm drain system on Bonita Glen Dr. Basin P.04 This 0.07-acre basin sheet flows from the south to the north where it drains into an existing channel onsite. Once in the channel, the water is conveyed north until it enters an existing inlet and then is conveyed through the existing storm drain in Bonita Glen Dr. Preliminary Drainage Study Bonita Glen Bonita Glen Dr., Chula Vista, CA 91910 7 Basin P.05 This 0.74-acre basin will sheet flow from the east to an existing stream onsite. Once in the stream, the water will be conveyed to an existing public storm drain system (POC ‘A’) that runs through Bonita Glen Dr. Basin P.06 This 1.11-acre basin sheet flows from southeast to northwest to a proposed inlet. The water is conveyed via the proposed storm drain and is directed into a proposed biofiltration basin. Once the water passes through the biofiltration basin it enters into the proposed storm drain system where it is taken to the existing storm drain system through Bonita Glen Dr. Basin P.07 This 2.33-acre basin sheet flows from south to north along the proposed surface parking and sheet flows along Vista Drive where it then becomes shallow concentrated flow. Runoff will be captured at the end of the cul-de-sac and conveyed via proposed storm drain that will be directed into a proposed biofiltration basin. Once through the biofiltration basin, the water enters a proposed catch basin and proposed storm drain system and will be conveyed to the existing storm drain system on Bonita Glen Dr. Refer to the “Proposed Hydrology Map” contained within Appendix ‘B’ for graphical depiction of the site’s developed hydrologic characteristics. Refer to the table below for a summary of proposed flow estimates analyzed in this report. Table No. 2 – Proposed Hydrology Summary Note: The ‘C’ factor used to determine runoff was determined on a basin by basin analysis of pervious vs. impervious area. The ‘C’ factor was determined using Storm and Sanitary Analysis. POC AREA (AC) RUNOFF 'C' Q 50-YR (CFS) Q 100-YR (CFS) ‘A’ 5.68 0.66 76.19 76.19 Preliminary Drainage Study Bonita Glen Bonita Glen Dr., Chula Vista, CA 91910 8 VI. DISCUSSION Based on the calculations contained herein, it is anticipated that the project will result in an increase in peak flow for the 50-year and 100-year storm frequencies at the point of compliance (55.11 cfs to 76.19 cfs). The increase in flow rates requires a storage volume of 6,506 cubic feet from onsite runoff. This volume will be detained via surface ponding and rock storage layers located in the proposed biofiltration basins. Outlet control will be provided in the biofiltration basins and discharge directly into the City’s storm drain infrastructure along Bonita Glen Drive. The existing 33” public storm drain has a full flow capacity of 76.64 cfs based upon the “as-built” slope of 2.1%. Placing Basin 1 & 2 in the 100- year floodplain will not affect the floodplain. In existing conditions, the floodplain area consists of dirt and shrubs, and during storm events, all runoff is directed into the existing creek without any storage/outlet control. To mitigate the increase in Q100 flows within the existing creek, the creek banks will be graded up to create a larger open channel capable of handling the required flows. Increasing the creek banks will be designed so that surface flow will not overtop the banks and flood onto the adjacent developments. VII. CONCLUSIONS This study has documented the existing and developed drainage conditions for Bonita Glen. According to the hydrology analysis and supporting calculations, it is anticipated that although the peak flow rate will increase, there will be no adverse drainage impacts on the hydrologic condition of the site. The additional runoff generated from onsite improvements will be mitigated via storage layers and surface ponding within the biofiltration basins. An overflow structure in the basin connected to the existing storm drain system will be used to prevent flooding. Based on REC Consultant’s report: “Hydrologic & Hydraulic Analysis for Bonita Glen Creek” dated Janurary 25, 2018, is was determined that during 100-year event conditions the creek floods overtopping the channel section and extending onto the surrounding areas. To mitigate these conditions, the creek banks were raised to allow the creek to handle this capacity and retain all flow within its banks. Additionally, the downstream existing 33” RCP public storm drain will be able to handle the mitigated 100 year flowrate of 55.11 cfs. APPENDIX A REFERENCE MATERIAL 5.0 50 T E C H N I C A L M E M O R A N D U M : H y d r o l o g i c & H y d r a u l i c A n a l y s i s f o r B o n i t a G l e n C r e e k Prepared For: Silvergate Development Prepared by: Luis Parra, PhD, CPSWQ, ToR, D.WRE. R.C.E. 66377 REC Consultants 2442 Second Avenue San Diego, CA 92101 Telephone: (619) 232-9200 TECHNICAL MEMORANDUM TO: Silvergate Development FROM: Luis Parra, PhD, PE, CPSWQ, ToR, D.WRE. David Edwards, PE. DATE: January 25, 2018. Revised: June 20, 2018. RE: Hydrologic and Hydraulic Analysis for Bonita Glen Creek INTRODUCTION This memorandum summarizes the approach used to model the hydrologic and hydraulics of the creek located within the proposed residential use site in the City of Chula Vista. The purpose of this study is determine the proposed creeks flow capacity using standard 2, 10 and 100-year standard 6-hour design storm events. Hydrology calculations were performed using methodology outlined within the 2003 San Diego County Hydrology Manual with additional input data obtained from the National Oceanic and Atmospheric Administration (NOAA) and the United States Geological Service (USGS) StreamStats website for rainfall precipitation and watershed tributary data respectively. PROJECT SUMMARY The Bonita Glen project site consists of a proposed residential use site that is bifurcated by an existing natural stream. In developed conditions, the creek is to remain in a natural state with graded embankments to the east and west of the delineated existing creek while leaving the creek in its natural existing condition. HYDROLOGY ANALYSIS Per the USGS Streamstats analysis undertaken for the project site (see Appendix 1), the existing creek has a tributary area of approximately 53 Acres comprising of predominantly developed residential areas. The Streamstats identified the tributary area as having an impervious percentage of 38.1% and an overland flow length of approximately 1 mile. Per the County of San Diego Hydrology Manual (SDHM), as the tributary area is less than 1 square mile, the modified rational method was to be used to determine the peak flow for the channel. Runoff Coefficient Determination Using the following equation from section 3.1.2 of the San Diego County Hydrology Manual: ܥൌͲǤͻݔሺΨܫ݉݌݁ݎݒ݅݋ݑݏ ሻ ൅ܥ௣ ݔሺͳ െ Ψܫ݉݌݁ݎݒ݅݋ݑݏሻ Where Cp is the pervious coefficient runoff coefficient for the natural hydrologic soil class, in this case hydrologic soil class D, Cp = 0.35. The overall weighted runoff coefficient for the tributary area is 0.56. Bonita Glen Creek January 25, 2018. Revised: June 20, 2018. Time of Concentration Per the USGS Streamstats analysis, the watershed tributary to the creek has an overland flow length of 1 mile with a discharge elevation of approximately 60 ft and an upstream starting elevation of 160 ft. It was determined that an overland flow time of 25 minutes was representative of the tributary area, according to the Kirpich Nomograph, figure 3-4, San Diego County Hydrology Manual (see Appendix 1). Precipitation The project site was located on the USGS NOAA 14 Atlas website to determine the rainfall precipitation. Table 1 below illustrates the precipitation for the 15, 25 and 30 minute intervals. It should be noted that the 25 minute interval is not provided by NOAA and was interpolated from their data set (see Appendix 1 for additional calculations). Table 1 – NOAA 14 Precipitations Design Storm 15 Minute (inches) 25 Minute (inches) 30 Minute (inches) 2-Year 0.240 0.307 0.335 10-Year 0.362 0.462 0.504 100-Year 0.563 0.720 0.786 Given that intensity is a function of precipitation and time, we can determine the following relationship: ܫ݊ݐ݁݊ݏ݅ݐݕ ൌ ܲݎ݁ܿ݅݌݅ݐܽݐ݅݋݊ሺ݄݅݊ܿ݁ݏሻ ܶ݅݉݁ሺ݄݋ݑݎݏሻ The rainfall intensities were then calculated accordingly in Table 2 below. Table 2 – NOAA 14 Rainfall Intensities Design Storm 15 Minute (in/hour) 25 Minute (in/hour) 30 Minute (in/hour) 2-Year 0.96 0.74 0.67 10-Year 1.45 1.11 1.01 100-Year 2.25 1.73 1.57 Using the rational method equation: ܳ ൌ ܥݔܫݔܣ Where C is the runoff coefficient, I is the rainfall intensity (assuming a 25 minute time of concentration) and A is the tributary area (about 53 acres), the flows tributary to the creek are provided in Table 3. Table 3 – Rational Method Peak Flow Time of Concentration 2-Year 10-Year 100-Year 25 Minutes 21.9 cfs 32.9 cfs 51.3 cfs Bonita Glen Creek January 25, 2018. Revised: June 20, 2018. Comparison with Chula Vista Drainage Master Plan Q100. The 100 year peak flow (51 cfs) is 77% of the value determined by the City of Chula Vista Master Plan Q100 (66 cfs). The difference can be attributed to the difference in intensity: For small Tc, NOAA updated intensity values are smaller than the recommended Hydrology Manual of the San Diego, which are based on the intensity equation. For example, in this project, the 6 hr – 100 yr rainfall event is about 2.65 inches, which determines an intensity of 2.47 in/hr for a time of concentration of 25 min. This intensity is 43% higher than NOAA’s (or in other words, NOAA’s intensity in the location for Tc = 25 min is 70% of the old intensities by the County Manual). Therefore, NOAA intensity in itself explains the difference in the peak. Notice that the use of County’s intensity in our model will give us a peak flow even larger than 66 cfs (Q= 0.56·2.47·53 = 73 cfs) which means that the selection of C in this study is more conservative than in the Master Drainage Study. The author of this study believes that NOAA’s new intensities are more accurate and precise than maps prepared in the 90’s by the County as more data and a better statistical analysis was used by NOAA in their web-site analysis. As a consequence, the peak flow of 51 cfs (and all other peak flows) will be considered more adequate for the purposes of this analysis. HYDRAULIC ANALYSIS In order to assess the conveyance capacity of the creek, a normal depth analysis was to be taken at the most hydraulically limited section throughout the reach of the project site. It was determined that the most conservative analysis location was at the southernmost structure adjacent to Bonita Glen Road. A detail of the section is provided below in Exhibit 1. Exhibit 1 – Critical Creek Section Bonita Glen Creek January 25, 2018. Revised: June 20, 2018. Per the topographic information available, it was calculated that the creek at this location has a channel slope of approximately 3.3%. A manning’s roughness coefficient of 0.04 was selected to represent the natural light grass vegetation plus sandy bottom found within the current creek. The creek has a flow line invert of 58.4 ft and a top of bank elevation of 59.9 ft providing a maximum channel conveyance depth of 1.5 ft. A normal depth analysis for the section was undertaken with AutoDesk AutoCAD Hydraflow, the result of which is summarized below in Table 4 and is provided in detail in Appendix B of this report. Table 4 – Summary of Creek Flow Depth Analysis Location 2-Year 10-Year 100-Year Maximum Flow Depth Allowable Southern Parking Lot 1.14 ft 1.32 ft 1.62 ft 1.50 ft Per the previous environmental assessment of the creek prepared by Dudek (and also confirmed by Lisa Honma of the RWQCB in a site visit on June 21, 2017) it was determined that a typical flow width of about 1.5 ft exits, and an additional buffer of 10 ft was recommended (for a total width of 11.5 ft to be maintained out of reach from development). Table 5 below illustrates the flow width experienced by the creek section selected for the design storms analyzed within this study. Table 5 – Summary of Creek Flow Width Analysis Location 2-Year 10-Year 100-Year Maximum Flow Width Allowable Southern Parking Lot 8.63 ft 9.81 ft 15.61 ft 11.5 ft Bonita Glen Creek January 25, 2018. Revised: June 20, 2018. SUMMARY This study has demonstrated that the proposed creek within the Bonita Glen project can safely convey the 2 and 10-year design peak flow without overtopping or exceeding the allowed width buffer, which demonstrated that the delineation of the creek main section using biological methods is consistent with the hydraulic calculations performed here. However, the 100-year flow is shown to be overtopping the channel section and extend beyond the buffer area, which is consistent with typical 100-year flood analysis where creeks spill out of their banks. If a floodplain determination is needed in the future within the creek, additional analysis of the system using HEC-RAS (or an equivalent 1-D hydraulic model) will be required for design purposes. KEY ASSUMPTIONS 1. Type D Soils is representative of the existing condition site. ATTACHMENTS 1. Hydrologic Analysis (USGS Streamstats, NOAA 14 Precipitation) 2. Hydraulic Analysis (Hydraflow Normal Depth) REFERENCES [1] – “County of San Diego Hydrology Manual”, June 2003. BonitaGlenCreek January25,2018 APPENDIX1–RATIONALMETHODANALYSIS 1/24/2018 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=32.6428&lon=-117.0612&data=depth&units=english&series=pds 1/4 NOAA Atlas 14, Volume 6, Version 2 Location name: Chula Vista, California, USA* Latitude: 32.6428°, Longitude: -117.0612° Elevation: 170.95 ft** * source: ESRI Maps ** source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Sarah Dietz, Sarah Heim, Lillian Hiner, Kazungu Maitaria, Deborah Martin, Sandra Pavlovic, Ishani Roy, Carl Trypaluk, Dale Unruh, Fenglin Yan, Michael Yekta, Tan Zhao, Geoffrey Bonnin, Daniel Brewer, Li-Chuan Chen, Tye Parzybok, John Yarchoan NOAA, National Weather Service, Silver Spring, Maryland PF_tabular | PF_graphical | Maps_&_aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 0.110 (0.092‑0.133) 0.139 (0.116‑0.168) 0.177 (0.147‑0.214) 0.209 (0.172‑0.255) 0.253 (0.202‑0.320) 0.288 (0.225‑0.373) 0.325 (0.247‑0.431) 0.364 (0.269‑0.497) 0.417 (0.296‑0.595) 0.460 (0.314‑0.680) 10-min 0.158 (0.132‑0.191) 0.199 (0.166‑0.240) 0.253 (0.211‑0.307) 0.299 (0.247‑0.366) 0.363 (0.290‑0.459) 0.413 (0.323‑0.535) 0.466 (0.355‑0.618) 0.521 (0.385‑0.712) 0.598 (0.424‑0.853) 0.659 (0.451‑0.974) 15-min 0.191 (0.160‑0.231) 0.240 (0.201‑0.291) 0.306 (0.255‑0.372) 0.362 (0.299‑0.442) 0.439 (0.350‑0.556) 0.500 (0.390‑0.647) 0.563 (0.429‑0.747) 0.630 (0.466‑0.861) 0.723 (0.512‑1.03) 0.797 (0.545‑1.18) 30-min 0.267 (0.223‑0.322) 0.335 (0.280‑0.405) 0.428 (0.356‑0.518) 0.504 (0.417‑0.617) 0.612 (0.488‑0.775) 0.697 (0.544‑0.902) 0.786 (0.598‑1.04) 0.879 (0.650‑1.20) 1.01 (0.715‑1.44) 1.11 (0.760‑1.64) 60-min 0.372 (0.311‑0.449) 0.467 (0.390‑0.565) 0.596 (0.496‑0.722) 0.703 (0.581‑0.859) 0.853 (0.680‑1.08) 0.971 (0.758‑1.26) 1.10 (0.833‑1.45) 1.23 (0.906‑1.67) 1.41 (0.996‑2.00) 1.55 (1.06‑2.29) 2-hr 0.514 (0.430‑0.621) 0.646 (0.540‑0.782) 0.821 (0.684‑0.995) 0.963 (0.796‑1.18) 1.16 (0.924‑1.47) 1.31 (1.02‑1.69) 1.46 (1.11‑1.94) 1.62 (1.20‑2.21) 1.84 (1.30‑2.62) 2.01 (1.37‑2.96) 3-hr 0.620 (0.519‑0.749) 0.781 (0.652‑0.944) 0.990 (0.825‑1.20) 1.16 (0.959‑1.42) 1.39 (1.11‑1.76) 1.57 (1.23‑2.03) 1.75 (1.33‑2.32) 1.94 (1.43‑2.65) 2.19 (1.55‑3.12) 2.38 (1.63‑3.52) 6-hr 0.809 (0.677‑0.977) 1.02 (0.853‑1.24) 1.30 (1.08‑1.57) 1.52 (1.26‑1.86) 1.82 (1.46‑2.31) 2.06 (1.61‑2.66) 2.29 (1.74‑3.04) 2.53 (1.87‑3.46) 2.86 (2.02‑4.07) 3.11 (2.12‑4.59) 12-hr 1.05 (0.880‑1.27) 1.33 (1.11‑1.61) 1.70 (1.41‑2.06) 2.00 (1.65‑2.44) 2.41 (1.93‑3.05) 2.73 (2.13‑3.54) 3.06 (2.33‑4.06) 3.41 (2.52‑4.65) 3.87 (2.74‑5.52) 4.24 (2.90‑6.27) 24-hr 1.30 (1.14‑1.51) 1.65 (1.44‑1.92) 2.12 (1.85‑2.48) 2.51 (2.17‑2.96) 3.06 (2.57‑3.71) 3.49 (2.88‑4.31) 3.93 (3.17‑4.97) 4.40 (3.46‑5.71) 5.06 (3.83‑6.81) 5.58 (4.10‑7.75) 2-day 1.60 (1.40‑1.86) 2.06 (1.80‑2.40) 2.67 (2.33‑3.13) 3.18 (2.76‑3.75) 3.88 (3.26‑4.71) 4.43 (3.65‑5.48) 4.99 (4.03‑6.31) 5.58 (4.39‑7.23) 6.38 (4.84‑8.60) 7.02 (5.16‑9.75) 3-day 1.79 (1.57‑2.09) 2.33 (2.04‑2.72) 3.05 (2.66‑3.57) 3.64 (3.15‑4.29) 4.44 (3.74‑5.39) 5.07 (4.18‑6.26) 5.70 (4.60‑7.21) 6.36 (5.00‑8.24) 7.26 (5.50‑9.77) 7.96 (5.85‑11.1) 4-day 1.94 (1.70‑2.26) 2.54 (2.22‑2.96) 3.33 (2.91‑3.90) 3.98 (3.45‑4.69) 4.86 (4.09‑5.90) 5.54 (4.57‑6.85) 6.24 (5.03‑7.88) 6.95 (5.47‑9.01) 7.92 (6.01‑10.7) 8.68 (6.38‑12.1) 7-day 2.25 (1.97‑2.62) 2.95 (2.58‑3.44) 3.88 (3.39‑4.54) 4.64 (4.02‑5.46) 5.67 (4.77‑6.89) 6.47 (5.34‑8.01) 7.29 (5.88‑9.21) 8.13 (6.40‑10.5) 9.27 (7.02‑12.5) 10.2 (7.46‑14.1) 10-day 2.47 (2.16‑2.88) 3.25 (2.84‑3.79) 4.27 (3.73‑5.00) 5.11 (4.43‑6.02) 6.25 (5.26‑7.59) 7.13 (5.88‑8.82) 8.02 (6.48‑10.1) 8.94 (7.04‑11.6) 10.2 (7.73‑13.7) 11.2 (8.20‑15.5) 20-day 2.99 (2.62‑3.48) 3.96 (3.46‑4.61) 5.22 (4.55‑6.10) 6.24 (5.41‑7.35) 7.62 (6.41‑9.24) 8.67 (7.15‑10.7) 9.73 (7.85‑12.3) 10.8 (8.50‑14.0) 12.2 (9.28‑16.5) 13.4 (9.81‑18.6) 30-day 3.55 (3.11‑4.14) 4.71 (4.12‑5.50) 6.22 (5.43‑7.27) 7.42 (6.43‑8.74) 9.03 (7.60‑11.0) 10.2 (8.46‑12.7) 11.5 (9.25‑14.5) 12.7 (9.99‑16.5) 14.3 (10.8‑19.3) 15.5 (11.4‑21.6) 45-day 4.17 (3.65‑4.86) 5.53 (4.84‑6.45) 7.27 (6.34‑8.50) 8.65 (7.49‑10.2) 10.5 (8.80‑12.7) 11.8 (9.76‑14.6) 13.2 (10.6‑16.6) 14.5 (11.4‑18.8) 16.3 (12.3‑21.9) 17.6 (12.9‑24.4) 60-day 4.84 (4.24‑5.64) 6.40 (5.60‑7.47) 8.37 (7.31‑9.79) 9.92 (8.59‑11.7) 11.9 (10.0‑14.5) 13.4 (11.1‑16.6) 14.9 (12.0‑18.8) 16.3 (12.8‑21.2) 18.2 (13.8‑24.5) 19.6 (14.4‑27.2) 1/24/2018 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=32.6428&lon=-117.0612&data=depth&units=english&series=pds 2/4 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top PF graphical curve plots Back to Top Maps & aerials Small scale terrain + – 3km 2mi 1/24/2018 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=32.6428&lon=-117.0612&data=depth&units=english&series=pds 3/4 Large scale terrain Large scale map Large scale aerial Back to Top Error 500: Internal Server Error. Please try another location. + – 100km 60mi + – 100km 60mi + – 100km 60mi NOAAValuesInterpretation 2ͲYear 10ͲYear 100ͲYear 15 0.24 0.362 0.563 25 0.307 0.462 0.720 30 0.335 0.504 0.786 y=0.065217x0.481126 R²=1.000000 y=0.099358x0.477434 R²=1.000000 y=0.152878x0.481394 R²=1.000000 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 10203040 Series1 Series2 Series3 Power(Series1) Power(Series2) Power(Series3) BonitaGlenCreek January25,2018 APPENDIX2–HYDRAULICANALYSIS Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Thursday, Jan 25 2018 <Name> User-defined Invert Elev (ft) = 58.40 Slope (%) = 3.30 N-Value = 0.040 Calculations Compute by: Known Q Known Q (cfs) = 21.90 (Sta, El, n)-(Sta, El, n)... ( 0.00, 59.90)-(4.40, 59.90, 0.040)-(9.50, 58.40, 0.040)-(14.50, 59.60, 0.040)-(18.20, 61.00, 0.040) Highlighted Depth (ft) = 1.14 Q (cfs) = 21.90 Area (sqft) = 4.92 Velocity (ft/s) = 4.45 Wetted Perim (ft) = 8.93 Crit Depth, Yc (ft) = 1.16 Top Width (ft) = 8.63 EGL (ft) = 1.45 -2 0 2 4 6 8 10 12 14 16 18 20 22 Elev (ft)Depth (ft)Section 57.00 -1.40 58.00 -0.40 59.00 0.60 60.00 1.60 61.00 2.60 62.00 3.60 Sta (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Thursday, Jan 25 2018 <Name> User-defined Invert Elev (ft) = 58.40 Slope (%) = 3.30 N-Value = 0.040 Calculations Compute by: Known Q Known Q (cfs) = 32.90 (Sta, El, n)-(Sta, El, n)... ( 0.00, 59.90)-(4.40, 59.90, 0.040)-(9.50, 58.40, 0.040)-(14.50, 59.60, 0.040)-(18.20, 61.00, 0.040) Highlighted Depth (ft) = 1.32 Q (cfs) = 32.90 Area (sqft) = 6.58 Velocity (ft/s) = 5.00 Wetted Perim (ft) = 10.16 Crit Depth, Yc (ft) = 1.36 Top Width (ft) = 9.81 EGL (ft) = 1.71 -2 0 2 4 6 8 10 12 14 16 18 20 22 Elev (ft)Depth (ft)Section 57.00 -1.40 58.00 -0.40 59.00 0.60 60.00 1.60 61.00 2.60 62.00 3.60 Sta (ft) Channel Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Thursday, Jan 25 2018 <Name> User-defined Invert Elev (ft) = 58.40 Slope (%) = 3.30 N-Value = 0.040 Calculations Compute by: Known Q Known Q (cfs) = 51.30 (Sta, El, n)-(Sta, El, n)... ( 0.00, 59.90)-(4.40, 59.90, 0.040)-(9.50, 58.40, 0.040)-(14.50, 59.60, 0.040)-(18.20, 61.00, 0.040) Highlighted Depth (ft) = 1.62 Q (cfs) = 51.30 Area (sqft) = 10.30 Velocity (ft/s) = 4.98 Wetted Perim (ft) = 16.04 Crit Depth, Yc (ft) = 1.66 Top Width (ft) = 15.61 EGL (ft) = 2.01 -2 0 2 4 6 8 10 12 14 16 18 20 22 Elev (ft)Depth (ft)Section 57.00 -1.40 58.00 -0.40 59.00 0.60 60.00 1.60 61.00 2.60 62.00 3.60 Sta (ft) APPENDIX B EXISTING HYDROLOGY [CALCULATIONS FROM AUTODESK SSA] EXISTING STORM DRAIN SYSTEM Autodesk Storm and Sanitary AnalysisAutodesk Storm and Sanitary Analysis XS-01 XS-01 XS-02 XS-03 XS-04 EXISTING CONDITIONS – CROSS SECTIONS 1522.0 Existing Output Autodesk® Storm and Sanitary Analysis 2016 - Version 12.0.42 (Build 0) ----------------------------------------------------------------------------------------- ******************* Project Description ******************* File Name ................. 1522.00 Existing basin 1 alt.SPF Description ............... H:\1500\1522.00 - Silvergate Development - Bonita Glen Due Dilligence\Engineering\Reports\Drainage\1522.00 Existing Drainage Map.dwg **************** Analysis Options **************** Flow Units ................ cfs Subbasin Hydrograph Method. Rational [County of San Diego Method] Time of Concentration...... SCS TR-55 Return Period.............. 50/100 year 2.5p6 Link Routing Method ....... Hydrodynamic Storage Node Exfiltration.. None Starting Date ............. SEP-22-2017 00:00:00 Ending Date ............... SEP-22-2017 06:30:00 Report Time Step .......... 00:00:10 ************* Element Count ************* Number of subbasins ....... 4 Number of nodes ........... 6 Number of links ........... 5 **************** Subbasin Summary **************** Page 1 1522.0 Existing Output Subbasin Total Area ID acres ------------------------------ {_}.E.1 2.57 {_}.E.2 1.64 {_}.E.3 0.95 {_}.E.4 0.30 ************ Node Summary ************ Node Element Invert Maximum Ponded External ID Type Elevation Elev. Area Inflow ft ft ft² ------------------------------------------------------------------------------ Jun-01 JUNCTION 63.00 67.00 0.00 Yes Jun-02 JUNCTION 51.43 56.00 0.00 Jun-03 JUNCTION 48.50 55.00 0.00 Jun-04 JUNCTION 55.04 59.00 0.00 Jun-05 JUNCTION 58.38 64.00 0.00 POC'A' OUTFALL 40.76 42.08 0.00 ************ Link Summary ************ Link From Node To Node Element Length Slope Manning's ID Type ft % Roughness -------------------------------------------------------------------------------------------- Link-01 Jun-01 Jun-05 CHANNEL 52.0 8.8846 0.0270 Link-02 Jun-02 Jun-03 CHANNEL 134.2 2.1838 0.0270 Link-03 Jun-04 Jun-02 CHANNEL 134.9 2.6753 0.0270 Link-05 Jun-03 POC'A' CHANNEL 119.6 6.4575 0.0270 Link-06 Jun-05 Jun-04 CHANNEL 116.3 2.8711 0.0270 Page 2 1522.0 Existing Output ********************* Cross Section Summary ********************* Link Shape Depth/ Width No. of Cross Full Flow Design ID Diameter Barrels Sectional Hydraulic Flow Area Radius Capacity ft ft ft² ft cfs ---------------------------------------------------------------------------------------------------------- Link-01 IRREGULAR 1.50 10.00 1 8.25 0.79 115.95 Link-02 IRREGULAR 1.50 10.00 1 8.25 0.79 57.48 Link-03 IRREGULAR 1.80 10.00 1 10.75 1.03 98.45 Link-05 IRREGULAR 1.30 10.00 1 6.75 0.65 71.00 Link-06 IRREGULAR 1.50 10.00 1 8.25 0.79 65.91 **************** Transect Summary **************** Transect XS-01 Area: 0.0004 0.0016 0.0037 0.0065 0.0102 0.0147 0.0200 0.0262 0.0331 0.0409 0.0495 0.0589 0.0691 0.0802 0.0920 0.1047 0.1182 0.1325 0.1477 0.1636 0.1804 0.1980 0.2164 0.2356 0.2557 0.2765 0.2982 0.3207 0.3440 0.3682 0.3931 0.4189 0.4455 0.4729 0.5011 0.5302 0.5600 0.5907 0.6222 0.6545 0.6875 0.7207 0.7544 0.7884 0.8227 0.8575 0.8925 0.9280 0.9638 1.0000 Hrad: 0.0182 0.0364 0.0546 0.0728 0.0910 0.1092 0.1274 0.1456 0.1638 0.1820 0.2002 0.2184 0.2366 0.2548 0.2730 0.2912 0.3094 0.3275 0.3457 0.3639 Page 3 1522.0 Existing Output 0.3821 0.4003 0.4185 0.4367 0.4549 0.4731 0.4913 0.5095 0.5277 0.5459 0.5641 0.5823 0.6005 0.6187 0.6369 0.6551 0.6733 0.6915 0.7097 0.7279 0.7560 0.7839 0.8116 0.8391 0.8664 0.8935 0.9204 0.9471 0.9736 1.0000 Width: 0.0225 0.0450 0.0675 0.0900 0.1125 0.1350 0.1575 0.1800 0.2025 0.2250 0.2475 0.2700 0.2925 0.3150 0.3375 0.3600 0.3825 0.4050 0.4275 0.4500 0.4725 0.4950 0.5175 0.5400 0.5625 0.5850 0.6075 0.6300 0.6525 0.6750 0.6975 0.7200 0.7425 0.7650 0.7875 0.8100 0.8325 0.8550 0.8775 0.9000 0.9100 0.9200 0.9300 0.9400 0.9500 0.9600 0.9700 0.9800 0.9900 1.0000 Transect XS-02 Area: 0.0004 0.0018 0.0040 0.0071 0.0110 0.0159 0.0216 0.0283 0.0358 0.0441 0.0534 0.0636 0.0746 0.0865 0.0993 0.1130 0.1276 0.1430 0.1594 0.1766 0.1947 0.2137 0.2335 0.2543 0.2759 0.2984 0.3218 0.3461 0.3712 0.3973 0.4242 0.4515 0.4791 0.5071 0.5353 0.5640 0.5929 0.6223 0.6519 0.6819 0.7122 0.7428 0.7738 0.8051 0.8367 0.8687 0.9010 0.9337 0.9667 1.0000 Hrad: 0.0168 0.0336 0.0505 0.0673 0.0841 0.1009 0.1177 0.1346 0.1514 0.1682 0.1850 0.2018 0.2187 0.2355 0.2523 0.2691 0.2859 0.3028 0.3196 0.3364 0.3532 0.3700 0.3869 0.4037 0.4205 0.4373 0.4541 0.4710 0.4878 0.5046 Page 4 1522.0 Existing Output 0.5260 0.5528 0.5794 0.6058 0.6319 0.6578 0.6835 0.7089 0.7342 0.7592 0.7840 0.8087 0.8332 0.8575 0.8816 0.9056 0.9294 0.9531 0.9766 1.0000 Width: 0.0264 0.0527 0.0791 0.1055 0.1318 0.1582 0.1845 0.2109 0.2373 0.2636 0.2900 0.3164 0.3427 0.3691 0.3955 0.4218 0.4482 0.4745 0.5009 0.5273 0.5536 0.5800 0.6064 0.6327 0.6591 0.6855 0.7118 0.7382 0.7645 0.7909 0.8100 0.8200 0.8300 0.8400 0.8500 0.8600 0.8700 0.8800 0.8900 0.9000 0.9100 0.9200 0.9300 0.9400 0.9500 0.9600 0.9700 0.9800 0.9900 1.0000 Transect XS-03 Area: 0.0004 0.0016 0.0037 0.0065 0.0102 0.0147 0.0200 0.0262 0.0331 0.0409 0.0495 0.0589 0.0691 0.0802 0.0920 0.1047 0.1182 0.1325 0.1477 0.1636 0.1804 0.1980 0.2164 0.2356 0.2557 0.2765 0.2982 0.3207 0.3440 0.3682 0.3931 0.4189 0.4455 0.4729 0.5011 0.5302 0.5600 0.5907 0.6222 0.6545 0.6875 0.7207 0.7544 0.7884 0.8227 0.8575 0.8925 0.9280 0.9638 1.0000 Hrad: 0.0182 0.0364 0.0546 0.0728 0.0910 0.1092 0.1274 0.1456 0.1638 0.1820 0.2002 0.2184 0.2366 0.2548 0.2730 0.2912 0.3094 0.3275 0.3457 0.3639 0.3821 0.4003 0.4185 0.4367 0.4549 0.4731 0.4913 0.5095 0.5277 0.5459 0.5641 0.5823 0.6005 0.6187 0.6369 0.6551 0.6733 0.6915 0.7097 0.7279 Page 5 1522.0 Existing Output 0.7560 0.7839 0.8116 0.8391 0.8664 0.8935 0.9204 0.9471 0.9736 1.0000 Width: 0.0225 0.0450 0.0675 0.0900 0.1125 0.1350 0.1575 0.1800 0.2025 0.2250 0.2475 0.2700 0.2925 0.3150 0.3375 0.3600 0.3825 0.4050 0.4275 0.4500 0.4725 0.4950 0.5175 0.5400 0.5625 0.5850 0.6075 0.6300 0.6525 0.6750 0.6975 0.7200 0.7425 0.7650 0.7875 0.8100 0.8325 0.8550 0.8775 0.9000 0.9100 0.9200 0.9300 0.9400 0.9500 0.9600 0.9700 0.9800 0.9900 1.0000 Transect XS-04 Area: 0.0004 0.0016 0.0036 0.0064 0.0100 0.0144 0.0197 0.0257 0.0325 0.0401 0.0485 0.0578 0.0678 0.0786 0.0903 0.1027 0.1160 0.1300 0.1448 0.1605 0.1769 0.1942 0.2123 0.2311 0.2508 0.2712 0.2925 0.3146 0.3374 0.3611 0.3856 0.4109 0.4369 0.4638 0.4915 0.5200 0.5493 0.5794 0.6103 0.6420 0.6745 0.7078 0.7419 0.7768 0.8125 0.8490 0.8862 0.9237 0.9617 1.0000 Hrad: 0.0193 0.0385 0.0578 0.0770 0.0963 0.1156 0.1348 0.1541 0.1733 0.1926 0.2119 0.2311 0.2504 0.2697 0.2889 0.3082 0.3274 0.3467 0.3660 0.3852 0.4045 0.4237 0.4430 0.4623 0.4815 0.5008 0.5200 0.5393 0.5586 0.5778 0.5971 0.6164 0.6356 0.6549 0.6741 0.6934 0.7127 0.7319 0.7512 0.7704 0.7897 0.8090 0.8282 0.8475 0.8667 0.8860 0.9137 0.9426 0.9714 1.0000 Page 6 1522.0 Existing Output Width: 0.0208 0.0417 0.0625 0.0833 0.1042 0.1250 0.1458 0.1667 0.1875 0.2083 0.2292 0.2500 0.2708 0.2917 0.3125 0.3333 0.3542 0.3750 0.3958 0.4167 0.4375 0.4583 0.4792 0.5000 0.5208 0.5417 0.5625 0.5833 0.6042 0.6250 0.6458 0.6667 0.6875 0.7083 0.7292 0.7500 0.7708 0.7917 0.8125 0.8333 0.8542 0.8750 0.8958 0.9167 0.9375 0.9583 0.9700 0.9800 0.9900 1.0000 ************************** Volume Depth Runoff Quantity Continuity acre-ft inches ************************** --------- ------- Total Precipitation ...... 0.520 1.143 Continuity Error (%) ..... 0.554 ************************** Volume Volume Flow Routing Continuity acre-ft Mgallons ************************** --------- --------- External Inflow .......... 35.454 11.553 External Outflow ......... 29.393 9.578 Initial Stored Volume .... 0.005 0.002 Final Stored Volume ...... 0.109 0.036 Continuity Error (%) ..... 0.000 ************************************** Runoff Coefficient Computations Report ************************************** ------------------- Subbasin {_}.E.1 ------------------- Page 7 1522.0 Existing Output Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- Streets, 25 years or greater 1.04 D (6%+) 0.90 - 1.56 - 0.35 Composite Area & Weighted Runoff Coeff. 2.60 0.57 ------------------- Subbasin {_}.E.2 ------------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- Cultivated Land, 25 years or greater 1.54 D (6%+) 0.35 Composite Area & Weighted Runoff Coeff. 1.54 0.35 ------------------- Subbasin {_}.E.3 ------------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- Cultivated Land, 25 years or greater 1.14 D (2-6%) 0.35 Composite Area & Weighted Runoff Coeff. 1.14 0.35 ------------------- Subbasin {_}.E.4 ------------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- Cultivated Land, 25 years or greater 0.30 D (0-2%) 0.35 Composite Area & Weighted Runoff Coeff. 0.30 0.35 *************************************************** SCS TR-55 Time of Concentration Computations Report Page 8 1522.0 Existing Output *************************************************** Sheet Flow Equation ------------------- Tc = (0.007 * ((n * Lf)^0.8)) / ((P^0.5) * (Sf^0.4)) Where: Tc = Time of Concentration (hrs) n = Manning's Roughness Lf = Flow Length (ft) P = 2 yr, 24 hr Rainfall (inches) Sf = Slope (ft/ft) Shallow Concentrated Flow Equation ---------------------------------- V = 16.1345 * (Sf^0.5) (unpaved surface) V = 20.3282 * (Sf^0.5) (paved surface) V = 15.0 * (Sf^0.5) (grassed waterway surface) V = 10.0 * (Sf^0.5) (nearly bare & untilled surface) V = 9.0 * (Sf^0.5) (cultivated straight rows surface) V = 7.0 * (Sf^0.5) (short grass pasture surface) V = 5.0 * (Sf^0.5) (woodland surface) V = 2.5 * (Sf^0.5) (forest w/heavy litter surface) Tc = (Lf / V) / (3600 sec/hr) Where: Tc = Time of Concentration (hrs) Lf = Flow Length (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) Channel Flow Equation --------------------- Page 9 1522.0 Existing Output V = (1.49 * (R^(2/3)) * (Sf^0.5)) / n R = Aq / Wp Tc = (Lf / V) / (3600 sec/hr) Where: Tc = Time of Concentration (hrs) Lf = Flow Length (ft) R = Hydraulic Radius (ft) Aq = Flow Area (ft²) Wp = Wetted Perimeter (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) n = Manning's Roughness ------------------- Subbasin {_}.E.1 ------------------- Sheet Flow Computations ----------------------- Subarea A Subarea B Subarea C Manning's Roughness: 0.40 0.00 0.00 Flow Length (ft): 300.00 0.00 0.00 Slope (%): 11.30 0.00 0.00 2 yr, 24 hr Rainfall (in): 1.75 1.75 1.75 Velocity (ft/sec): 0.14 0.00 0.00 Computed Flow Time (minutes): 34.98 0.00 0.00 Shallow Concentrated Flow Computations -------------------------------------- Subarea A Subarea B Subarea C Flow Length (ft): 93.00 0.00 0.00 Slope (%): 5.90 0.00 0.00 Surface Type: Grassed waterway Unpaved Unpaved Velocity (ft/sec): 3.64 0.00 0.00 Page 10 1522.0 Existing Output Computed Flow Time (minutes): 0.43 0.00 0.00 Channel Flow Computations ------------------------- Subarea A Subarea B Subarea C Manning's Roughness: 0.01 0.01 0.00 Flow Length (ft): 131.00 228.00 0.00 Channel Slope (%): 3.80 3.30 0.00 Cross Section Area (ft²): 1.13 12.56 0.00 Wetted Perimeter (ft): 1.63 4.97 0.00 Velocity (ft/sec): 17.48 38.63 0.00 Computed Flow Time (minutes): 0.12 0.10 0.00 ================================================================================================ Total TOC (minutes): 35.63 ================================================================================================ ------------------- Subbasin {_}.E.2 ------------------- Sheet Flow Computations ----------------------- Subarea A Subarea B Subarea C Manning's Roughness: 0.40 0.00 0.00 Flow Length (ft): 300.00 0.00 0.00 Slope (%): 10.80 0.00 0.00 2 yr, 24 hr Rainfall (in): 1.75 1.75 1.75 Velocity (ft/sec): 0.14 0.00 0.00 Computed Flow Time (minutes): 35.62 0.00 0.00 Shallow Concentrated Flow Computations -------------------------------------- Subarea A Subarea B Subarea C Flow Length (ft): 273.00 0.00 0.00 Slope (%): 5.30 0.00 0.00 Surface Type: Grassed waterway Unpaved Unpaved Page 11 1522.0 Existing Output Velocity (ft/sec): 3.45 0.00 0.00 Computed Flow Time (minutes): 1.32 0.00 0.00 ================================================================================================ Total TOC (minutes): 36.94 ================================================================================================ ------------------- Subbasin {_}.E.3 ------------------- Sheet Flow Computations ----------------------- Subarea A Subarea B Subarea C Manning's Roughness: 0.40 0.00 0.00 Flow Length (ft): 300.00 0.00 0.00 Slope (%): 3.80 0.00 0.00 2 yr, 24 hr Rainfall (in): 1.75 1.75 1.75 Velocity (ft/sec): 0.09 0.00 0.00 Computed Flow Time (minutes): 54.10 0.00 0.00 Shallow Concentrated Flow Computations -------------------------------------- Subarea A Subarea B Subarea C Flow Length (ft): 71.00 0.00 0.00 Slope (%): 4.90 0.00 0.00 Surface Type: Grassed waterway Unpaved Unpaved Velocity (ft/sec): 3.32 0.00 0.00 Computed Flow Time (minutes): 0.36 0.00 0.00 ================================================================================================ Total TOC (minutes): 54.45 ================================================================================================ ------------------- Subbasin {_}.E.4 ------------------- Page 12 1522.0 Existing Output Sheet Flow Computations ----------------------- Subarea A Subarea B Subarea C Manning's Roughness: 0.40 0.00 0.00 Flow Length (ft): 144.00 0.00 0.00 Slope (%): 1.40 0.00 0.00 2 yr, 24 hr Rainfall (in): 1.75 1.75 1.75 Velocity (ft/sec): 0.05 0.00 0.00 Computed Flow Time (minutes): 44.83 0.00 0.00 ================================================================================================ Total TOC (minutes): 44.83 ================================================================================================ *********************** Subbasin Runoff Summary *********************** --------------------------------------------------------------------------------------- Subbasin Accumulated Rainfall Total Peak Weighted Time of ID Precip Intensity Runoff Runoff Runoff Concentration in in/hr in cfs Coeff days hh:mm:ss --------------------------------------------------------------------------------------- {_}.E.1 1.10 1.85 0.63 2.71 0.570 0 00:35:37 {_}.E.2 1.12 1.81 0.39 1.04 0.350 0 00:36:56 {_}.E.3 1.28 1.41 0.45 0.47 0.350 0 00:54:27 {_}.E.4 1.19 1.60 0.42 0.17 0.350 0 00:44:49 --------------------------------------------------------------------------------------- ****************** Node Depth Summary ****************** ----------------------------------------------------------------------------------------- Node Average Maximum Maximum Time of Max Total Total Retention Page 13 1522.0 Existing Output ID Depth Depth HGL Occurrence Flooded Time Time Attained Attained Attained Volume Flooded ft ft ft days hh:mm acre-in minutes hh:mm:ss ----------------------------------------------------------------------------------------- Jun-01 3.99 4.00 67.00 0 00:00 0.66 389 0:00:00 Jun-02 4.56 4.57 56.00 0 00:01 73.43 389 0:00:00 Jun-03 4.13 6.50 55.00 0 00:01 0.00 0 0:00:00 Jun-04 3.16 5.74 60.78 0 00:01 0.00 0 0:00:00 Jun-05 6.13 7.19 65.57 0 00:00 0.04 0 0:00:00 POC'A' 6.24 6.24 47.00 0 00:00 0 0 0:00:00 ***************** Node Flow Summary ***************** ------------------------------------------------------------------------------------ Node Element Maximum Peak Time of Maximum Time of Peak ID Type Lateral Inflow Peak Inflow Flooding Flooding Inflow Occurrence Overflow Occurrence cfs cfs days hh:mm cfs days hh:mm ------------------------------------------------------------------------------------ Jun-01 JUNCTION 66.00 66.00 0 00:00 63.39 0 00:00 Jun-02 JUNCTION 2.71 74.19 0 00:01 61.38 0 00:01 Jun-03 JUNCTION 0.60 66.37 0 00:01 13.84 0 00:01 Jun-04 JUNCTION 1.04 69.26 0 00:00 11.53 0 00:01 Jun-05 JUNCTION 0.00 75.32 0 00:00 62.21 0 00:00 POC'A' OUTFALL 0.00 55.11 0 00:54 0.00 *********************** Outfall Loading Summary *********************** ----------------------------------------------- Outfall Node ID Flow Average Peak Frequency Flow Inflow Page 14 1522.0 Existing Output (%) cfs cfs ----------------------------------------------- POC'A' 99.78 54.83 55.11 ----------------------------------------------- System 99.78 54.83 55.11 ***************** Link Flow Summary ***************** ------------------------------------------------------------------------------------------------------------ -------------------- Link ID Element Time of Maximum Length Peak Flow Design Ratio of Ratio of Total Reported Type Peak Flow Velocity Factor during Flow Maximum Maximum Time Condition Occurrence Attained Analysis Capacity /Design Flow Surcharged days hh:mm ft/sec cfs cfs Flow Depth minutes ------------------------------------------------------------------------------------------------------------ -------------------- Link-01 CHANNEL 0 00:00 15.00 1.00 75.32 115.95 0.65 1.00 389 FLOODED Link-02 CHANNEL 0 00:01 11.39 1.00 66.35 57.48 1.15 1.00 388 FLOODED Link-03 CHANNEL 0 00:01 8.86 1.00 74.12 98.45 0.75 1.00 389 FLOODED Link-05 CHANNEL 0 00:54 8.16 1.00 55.11 71.00 0.78 1.00 389 FLOODED Link-06 CHANNEL 0 00:00 13.36 1.00 69.25 65.91 1.05 1.00 389 FLOODED Page 15 APPENDIX C PROPOSED HYDROLOGY [CALCULATIONS FROM AUTODESK SSA] PROPOSED STORM DRAIN SYSTEM Autodesk Storm and Sanitary AnalysisAutodesk Storm and Sanitary Analysis XS-01 XS-02 XS-03 XS-04 XS-05 XS-06 TRIANGULAR PROPOSED CONDITIONS – CROSS SECTIONS 1522.0 Prop Output Autodesk® Storm and Sanitary Analysis 2016 - Version 12.0.42 (Build 0) ----------------------------------------------------------------------------------------- ******************* Project Description ******************* File Name ................. 1522.00 PROP SSA NEW.SPF Description ............... H:\1500\1522.00 - Silvergate Development - Bonita Glen Due Dilligence\Engineering\Reports\Drainage\1522.00 Proposed Drainage Map.dwg **************** Analysis Options **************** Flow Units ................ cfs Subbasin Hydrograph Method. Rational [County of San Diego Method] Time of Concentration...... SCS TR-55 Return Period.............. 50/100 year 2.5P6 Link Routing Method ....... Kinematic Wave Storage Node Exfiltration.. None Starting Date ............. OCT-12-2017 00:00:00 Ending Date ............... OCT-12-2017 01:00:00 Report Time Step .......... 00:00:10 ************* Element Count ************* Number of subbasins ....... 7 Number of nodes ........... 17 Number of links ........... 16 Page 1 1522.0 Prop Output **************** Subbasin Summary **************** Subbasin Total Area ID acres ------------------------------ {_}._P.1 0.35 {_}._P.2 0.26 {_}._P.3 0.82 {_}._P.4 0.07 {_}._P.5 0.74 {_}._P.6 1.11 {_}._P.7 2.33 ************ Node Summary ************ Node Element Invert Maximum Ponded External ID Type Elevation Elev. Area Inflow ft ft ft² ------------------------------------------------------------------------------ Jun-01 JUNCTION 49.90 52.05 0.00 Jun-02 JUNCTION 43.60 47.20 0.00 Jun-03 JUNCTION 54.60 59.07 0.00 Jun-04 JUNCTION 59.00 63.89 0.00 Jun-05 JUNCTION 55.00 60.07 0.00 Jun-06 JUNCTION 55.04 59.28 0.00 Jun-07 JUNCTION 59.30 67.00 0.00 Yes Jun-08 JUNCTION 52.50 57.23 0.00 Jun-09 JUNCTION 48.50 51.60 0.00 Jun-10 JUNCTION 45.20 49.80 0.00 Jun-11 JUNCTION 51.60 53.10 0.00 Page 2 1522.0 Prop Output Jun-12 JUNCTION 42.00 47.80 0.00 Jun-13 JUNCTION 46.50 52.80 0.00 Jun-20 JUNCTION 58.17 64.17 0.00 Jun-21 JUNCTION 56.76 62.76 0.00 Jun-22 JUNCTION 54.28 60.28 0.00 POC'A' OUTFALL 40.76 43.51 0.00 ************ Link Summary ************ Link From Node To Node Element Length Slope Manning's ID Type ft % Roughness -------------------------------------------------------------------------------------------- Link-01 Jun-02 POC'A' CONDUIT 44.5 6.3763 0.0150 Link-02 Jun-03 Jun-01 CONDUIT 216.5 2.1713 0.0150 Link-03 Jun-04 Jun-03 CONDUIT 54.6 7.3193 0.0150 Link-04 Jun-05 Jun-03 CONDUIT 54.6 0.7325 0.0150 Link-05 Jun-01 Jun-02 CONDUIT 179.2 3.5148 0.0150 Link-06 Jun-07 Jun-20 CHANNEL 40.0 2.8271 0.0320 Link-07 Jun-06 Jun-22 CHANNEL 41.8 1.8173 0.0320 Link-08 Jun-08 Jun-09 CHANNEL 141.7 2.8237 0.0320 Link-09 Jun-09 POC'A' CHANNEL 108.0 7.1667 0.0320 Link-10 Jun-12 POC'A' CONDUIT 85.1 1.4564 0.0150 Link-11 Jun-13 Jun-12 CONDUIT 134.0 3.3572 0.0150 Link-12 Jun-10 Jun-12 CONDUIT 36.9 8.6839 0.0150 Link-13 Jun-11 Jun-13 CONDUIT 37.3 13.6619 0.0150 Link-20 Jun-20 Jun-21 CHANNEL 52.2 2.7032 0.0320 Link-21 Jun-21 Jun-06 CHANNEL 61.0 2.8220 0.0320 Link-22 Jun-22 Jun-08 CHANNEL 97.0 1.8341 0.0320 ********************* Cross Section Summary Page 3 1522.0 Prop Output ********************* Link Shape Depth/ Width No. of Cross Full Flow Design ID Diameter Barrels Sectional Hydraulic Flow Area Radius Capacity ft ft ft² ft cfs ---------------------------------------------------------------------------------------------------------- Link-01 CIRCULAR 1.50 1.50 1 1.77 0.38 22.99 Link-02 CIRCULAR 1.50 1.50 1 1.77 0.38 13.41 Link-03 CIRCULAR 1.00 1.00 1 0.79 0.25 8.35 Link-04 CIRCULAR 1.50 1.50 1 1.77 0.38 7.79 Link-05 CIRCULAR 1.50 1.50 1 1.77 0.38 17.07 Link-06 IRREGULAR 2.97 10.00 1 15.35 1.30 142.99 Link-07 IRREGULAR 4.24 27.50 1 80.60 2.69 976.59 Link-08 IRREGULAR 3.10 34.00 1 47.70 1.38 461.84 Link-09 TRIANGULAR 1.50 10.00 1 7.50 0.72 74.79 Link-10 CIRCULAR 2.75 2.75 1 5.94 0.69 55.31 Link-11 CIRCULAR 2.75 2.75 1 5.94 0.69 83.98 Link-12 CIRCULAR 1.00 1.00 1 0.79 0.25 9.10 Link-13 CIRCULAR 1.00 1.00 1 0.79 0.25 11.41 Link-20 IRREGULAR 2.83 16.40 1 24.55 1.47 242.58 Link-21 IRREGULAR 3.50 39.00 1 81.20 1.79 932.42 Link-22 IRREGULAR 4.73 27.50 1 83.81 2.89 1068.75 **************** Transect Summary **************** Transect XS-01 Area: 0.0004 0.0016 0.0036 0.0064 0.0100 0.0144 0.0196 0.0257 0.0325 0.0401 0.0485 0.0577 0.0678 0.0786 0.0902 0.1026 0.1159 0.1299 0.1447 0.1604 Page 4 1522.0 Prop Output 0.1768 0.1941 0.2121 0.2309 0.2506 0.2710 0.2923 0.3143 0.3372 0.3608 0.3853 0.4106 0.4366 0.4635 0.4912 0.5196 0.5489 0.5790 0.6098 0.6415 0.6740 0.7073 0.7413 0.7762 0.8119 0.8484 0.8857 0.9234 0.9615 1.0000 Hrad: 0.0197 0.0394 0.0591 0.0788 0.0985 0.1181 0.1378 0.1575 0.1772 0.1969 0.2166 0.2363 0.2560 0.2757 0.2954 0.3150 0.3347 0.3544 0.3741 0.3938 0.4135 0.4332 0.4529 0.4726 0.4923 0.5119 0.5316 0.5513 0.5710 0.5907 0.6104 0.6301 0.6498 0.6695 0.6892 0.7088 0.7285 0.7482 0.7679 0.7876 0.8073 0.8270 0.8467 0.8664 0.8861 0.9057 0.9273 0.9519 0.9761 1.0000 Width: 0.0207 0.0414 0.0622 0.0829 0.1036 0.1243 0.1451 0.1658 0.1865 0.2072 0.2279 0.2487 0.2694 0.2901 0.3108 0.3316 0.3523 0.3730 0.3937 0.4144 0.4352 0.4559 0.4766 0.4973 0.5181 0.5388 0.5595 0.5802 0.6009 0.6217 0.6424 0.6631 0.6838 0.7045 0.7253 0.7460 0.7667 0.7874 0.8082 0.8289 0.8496 0.8703 0.8910 0.9118 0.9325 0.9532 0.9700 0.9800 0.9900 1.0000 Transect XS-02 Area: 0.0004 0.0014 0.0032 0.0057 0.0089 0.0128 0.0175 0.0228 0.0289 0.0357 0.0431 0.0513 0.0603 0.0699 0.0802 Page 5 1522.0 Prop Output 0.0913 0.1030 0.1155 0.1287 0.1426 0.1572 0.1726 0.1886 0.2054 0.2228 0.2410 0.2599 0.2795 0.2998 0.3209 0.3426 0.3651 0.3949 0.4284 0.4622 0.4962 0.5305 0.5651 0.5999 0.6349 0.6703 0.7059 0.7417 0.7778 0.8142 0.8508 0.8877 0.9249 0.9623 1.0000 Hrad: 0.0180 0.0360 0.0539 0.0719 0.0899 0.1079 0.1258 0.1438 0.1618 0.1798 0.1978 0.2157 0.2337 0.2517 0.2697 0.2876 0.3056 0.3236 0.3416 0.3596 0.3775 0.3955 0.4135 0.4315 0.4494 0.4674 0.4854 0.5034 0.5214 0.5393 0.5573 0.5753 0.5911 0.6092 0.6297 0.6517 0.6748 0.6987 0.7231 0.7479 0.7729 0.7982 0.8235 0.8488 0.8742 0.8995 0.9247 0.9499 0.9750 1.0000 Width: 0.0189 0.0377 0.0566 0.0754 0.0943 0.1132 0.1320 0.1509 0.1697 0.1886 0.2075 0.2263 0.2452 0.2640 0.2829 0.3017 0.3206 0.3395 0.3583 0.3772 0.3960 0.4149 0.4338 0.4526 0.4715 0.4903 0.5092 0.5281 0.5469 0.5658 0.5846 0.6035 0.8827 0.8896 0.8965 0.9034 0.9103 0.9172 0.9241 0.9310 0.9379 0.9448 0.9517 0.9586 0.9655 0.9724 0.9793 0.9862 0.9931 1.0000 Transect XS-03 Area: 0.0003 0.0012 0.0027 0.0048 0.0075 0.0109 0.0148 0.0193 0.0244 0.0302 Page 6 1522.0 Prop Output 0.0365 0.0434 0.0510 0.0591 0.0681 0.0783 0.0898 0.1026 0.1167 0.1321 0.1488 0.1668 0.1861 0.2067 0.2286 0.2519 0.2764 0.3022 0.3293 0.3577 0.3875 0.4183 0.4494 0.4806 0.5120 0.5435 0.5752 0.6070 0.6389 0.6710 0.7033 0.7357 0.7682 0.8009 0.8337 0.8667 0.8998 0.9330 0.9665 1.0000 Hrad: 0.0191 0.0383 0.0574 0.0766 0.0957 0.1148 0.1340 0.1531 0.1723 0.1914 0.2105 0.2297 0.2488 0.2680 0.2988 0.3288 0.3538 0.3753 0.3940 0.4109 0.4264 0.4409 0.4547 0.4681 0.4811 0.4938 0.5064 0.5189 0.5314 0.5438 0.5562 0.5731 0.5942 0.6161 0.6387 0.6617 0.6851 0.7088 0.7328 0.7569 0.7811 0.8054 0.8297 0.8541 0.8785 0.9029 0.9272 0.9515 0.9758 1.0000 Width: 0.0179 0.0359 0.0538 0.0718 0.0897 0.1077 0.1256 0.1436 0.1615 0.1795 0.1974 0.2154 0.2333 0.2513 0.2841 0.3228 0.3615 0.4002 0.4389 0.4776 0.5163 0.5550 0.5937 0.6324 0.6712 0.7099 0.7486 0.7873 0.8260 0.8647 0.9034 0.9225 0.9268 0.9311 0.9354 0.9397 0.9440 0.9483 0.9526 0.9569 0.9612 0.9655 0.9698 0.9742 0.9785 0.9828 0.9871 0.9914 0.9957 1.0000 Transect XS-04 Area: 0.0032 0.0124 0.0233 0.0346 0.0463 Page 7 1522.0 Prop Output 0.0585 0.0710 0.0840 0.0975 0.1113 0.1256 0.1403 0.1554 0.1710 0.1870 0.2034 0.2202 0.2375 0.2551 0.2732 0.2918 0.3107 0.3301 0.3499 0.3701 0.3908 0.4118 0.4333 0.4553 0.4776 0.5004 0.5236 0.5472 0.5712 0.5957 0.6206 0.6459 0.6716 0.6975 0.7237 0.7502 0.7769 0.8039 0.8311 0.8586 0.8864 0.9144 0.9427 0.9712 1.0000 Hrad: 0.0157 0.0367 0.0671 0.0965 0.1250 0.1527 0.1797 0.2060 0.2316 0.2566 0.2810 0.3048 0.3281 0.3510 0.3733 0.3953 0.4168 0.4379 0.4586 0.4790 0.4991 0.5188 0.5382 0.5573 0.5762 0.5947 0.6131 0.6311 0.6490 0.6666 0.6840 0.7012 0.7182 0.7350 0.7517 0.7681 0.7844 0.8016 0.8188 0.8358 0.8527 0.8695 0.8862 0.9028 0.9193 0.9357 0.9519 0.9681 0.9841 1.0000 Width: 0.2203 0.3688 0.3834 0.3981 0.4128 0.4275 0.4422 0.4568 0.4715 0.4862 0.5009 0.5155 0.5302 0.5449 0.5596 0.5743 0.5889 0.6036 0.6183 0.6330 0.6477 0.6623 0.6770 0.6917 0.7064 0.7210 0.7357 0.7504 0.7651 0.7798 0.7944 0.8091 0.8238 0.8385 0.8532 0.8678 0.8825 0.8917 0.9007 0.9097 0.9188 0.9278 0.9368 0.9458 0.9549 0.9639 0.9729 0.9819 0.9910 1.0000 Transect XS-05 Area: Page 8 1522.0 Prop Output 0.0008 0.0032 0.0073 0.0129 0.0202 0.0291 0.0396 0.0512 0.0633 0.0759 0.0891 0.1028 0.1171 0.1319 0.1472 0.1630 0.1794 0.1964 0.2138 0.2318 0.2503 0.2694 0.2890 0.3092 0.3298 0.3511 0.3728 0.3951 0.4179 0.4413 0.4652 0.4896 0.5146 0.5401 0.5661 0.5927 0.6198 0.6474 0.6752 0.7034 0.7318 0.7605 0.7895 0.8187 0.8482 0.8780 0.9081 0.9385 0.9691 1.0000 Hrad: 0.0162 0.0324 0.0485 0.0647 0.0809 0.0971 0.1136 0.1450 0.1748 0.2035 0.2310 0.2576 0.2834 0.3083 0.3325 0.3561 0.3790 0.4014 0.4232 0.4445 0.4654 0.4858 0.5058 0.5254 0.5447 0.5636 0.5822 0.6006 0.6186 0.6363 0.6538 0.6711 0.6881 0.7049 0.7215 0.7379 0.7542 0.7721 0.7910 0.8100 0.8290 0.8481 0.8671 0.8862 0.9052 0.9242 0.9432 0.9622 0.9811 1.0000 Width: 0.0521 0.1042 0.1564 0.2085 0.2606 0.3127 0.3640 0.3813 0.3986 0.4158 0.4331 0.4504 0.4676 0.4849 0.5022 0.5194 0.5367 0.5540 0.5712 0.5885 0.6057 0.6230 0.6403 0.6575 0.6748 0.6921 0.7093 0.7266 0.7439 0.7611 0.7784 0.7957 0.8129 0.8302 0.8475 0.8647 0.8820 0.8935 0.9024 0.9113 0.9201 0.9290 0.9379 0.9468 0.9556 0.9645 0.9734 0.9823 0.9911 1.0000 Transect XS-06 Page 9 1522.0 Prop Output Area: 0.0002 0.0009 0.0021 0.0038 0.0059 0.0085 0.0116 0.0152 0.0192 0.0237 0.0287 0.0341 0.0401 0.0465 0.0533 0.0607 0.0685 0.0768 0.0856 0.0948 0.1045 0.1147 0.1254 0.1365 0.1481 0.1602 0.1728 0.1949 0.2243 0.2543 0.2850 0.3164 0.3485 0.3813 0.4148 0.4490 0.4839 0.5194 0.5557 0.5926 0.6302 0.6686 0.7076 0.7473 0.7877 0.8288 0.8705 0.9130 0.9562 1.0000 Hrad: 0.0212 0.0423 0.0635 0.0846 0.1058 0.1269 0.1481 0.1692 0.1904 0.2115 0.2327 0.2538 0.2750 0.2961 0.3173 0.3384 0.3596 0.3807 0.4019 0.4230 0.4442 0.4653 0.4865 0.5076 0.5288 0.5499 0.5711 0.5664 0.5585 0.5616 0.5714 0.5855 0.6026 0.6218 0.6425 0.6643 0.6868 0.7100 0.7335 0.7574 0.7815 0.8057 0.8300 0.8544 0.8787 0.9031 0.9274 0.9517 0.9759 1.0000 Width: 0.0107 0.0215 0.0322 0.0429 0.0536 0.0644 0.0751 0.0858 0.0965 0.1073 0.1180 0.1287 0.1394 0.1502 0.1609 0.1716 0.1824 0.1931 0.2038 0.2145 0.2253 0.2360 0.2467 0.2574 0.2682 0.2789 0.2896 0.6561 0.6718 0.6874 0.7030 0.7187 0.7343 0.7499 0.7655 0.7812 0.7968 0.8124 0.8281 0.8437 0.8593 0.8750 0.8906 0.9062 0.9218 0.9375 0.9531 0.9687 0.9844 1.0000 Page 10 1522.0 Prop Output ************************** Volume Depth Runoff Quantity Continuity acre-ft inches ************************** --------- ------- Total Precipitation ...... 0.374 0.790 Continuity Error (%) ..... 0.319 ************************** Volume Volume Flow Routing Continuity acre-ft Mgallons ************************** --------- --------- External Inflow .......... 5.455 1.778 External Outflow ......... 5.605 1.826 Initial Stored Volume .... 0.000 0.000 Final Stored Volume ...... 0.120 0.039 Continuity Error (%) ..... -0.002 ************************************** Runoff Coefficient Computations Report ************************************** -------------------- Subbasin {_}._P.1 -------------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 0.02 - 0.10 - 0.33 - 0.90 Composite Area & Weighted Runoff Coeff. 0.35 0.85 -------------------- Subbasin {_}._P.2 Page 11 1522.0 Prop Output -------------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 0.12 - 0.90 - 0.13 - 0.10 Composite Area & Weighted Runoff Coeff. 0.26 0.48 -------------------- Subbasin {_}._P.3 -------------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 0.56 - 0.90 - 0.25 - 0.10 Composite Area & Weighted Runoff Coeff. 0.82 0.65 -------------------- Subbasin {_}._P.4 -------------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 0.07 - 0.10 Composite Area & Weighted Runoff Coeff. 0.07 0.10 -------------------- Subbasin {_}._P.5 -------------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 0.02 - 0.90 Page 12 1522.0 Prop Output - 0.72 - 0.10 Composite Area & Weighted Runoff Coeff. 0.74 0.12 -------------------- Subbasin {_}._P.6 -------------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 0.98 - 0.90 - 0.13 - 0.10 Composite Area & Weighted Runoff Coeff. 1.11 0.80 -------------------- Subbasin {_}._P.7 -------------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 1.98 - 0.90 - 0.35 - 0.10 Composite Area & Weighted Runoff Coeff. 2.33 0.78 *************************************************** SCS TR-55 Time of Concentration Computations Report *************************************************** Sheet Flow Equation ------------------- Tc = (0.007 * ((n * Lf)^0.8)) / ((P^0.5) * (Sf^0.4)) Where: Page 13 1522.0 Prop Output Tc = Time of Concentration (hrs) n = Manning's Roughness Lf = Flow Length (ft) P = 2 yr, 24 hr Rainfall (inches) Sf = Slope (ft/ft) Shallow Concentrated Flow Equation ---------------------------------- V = 16.1345 * (Sf^0.5) (unpaved surface) V = 20.3282 * (Sf^0.5) (paved surface) V = 15.0 * (Sf^0.5) (grassed waterway surface) V = 10.0 * (Sf^0.5) (nearly bare & untilled surface) V = 9.0 * (Sf^0.5) (cultivated straight rows surface) V = 7.0 * (Sf^0.5) (short grass pasture surface) V = 5.0 * (Sf^0.5) (woodland surface) V = 2.5 * (Sf^0.5) (forest w/heavy litter surface) Tc = (Lf / V) / (3600 sec/hr) Where: Tc = Time of Concentration (hrs) Lf = Flow Length (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) Channel Flow Equation --------------------- V = (1.49 * (R^(2/3)) * (Sf^0.5)) / n R = Aq / Wp Tc = (Lf / V) / (3600 sec/hr) Page 14 1522.0 Prop Output Where: Tc = Time of Concentration (hrs) Lf = Flow Length (ft) R = Hydraulic Radius (ft) Aq = Flow Area (ft²) Wp = Wetted Perimeter (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) n = Manning's Roughness -------------------- Subbasin {_}._P.1 -------------------- Sheet Flow Computations ----------------------- Subarea A Subarea B Subarea C Manning's Roughness: 0.11 0.00 0.00 Flow Length (ft): 110.00 0.00 0.00 Slope (%): 2.00 0.00 0.00 2 yr, 24 hr Rainfall (in): 1.75 1.00 1.00 Velocity (ft/sec): 0.16 0.00 0.00 Computed Flow Time (minutes): 11.16 0.00 0.00 ================================================================================================ Total TOC (minutes): 11.16 ================================================================================================ -------------------- Subbasin {_}._P.2 -------------------- Sheet Flow Computations Page 15 1522.0 Prop Output ----------------------- Subarea A Subarea B Subarea C Manning's Roughness: 0.11 0.00 0.00 Flow Length (ft): 124.00 0.00 0.00 Slope (%): 2.00 0.00 0.00 2 yr, 24 hr Rainfall (in): 1.75 1.00 1.00 Velocity (ft/sec): 0.17 0.00 0.00 Computed Flow Time (minutes): 12.28 0.00 0.00 ================================================================================================ Total TOC (minutes): 12.28 ================================================================================================ -------------------- Subbasin {_}._P.3 -------------------- Sheet Flow Computations ----------------------- Subarea A Subarea B Subarea C Manning's Roughness: 0.11 0.00 0.00 Flow Length (ft): 275.00 0.00 0.00 Slope (%): 2.00 0.00 0.00 2 yr, 24 hr Rainfall (in): 1.75 1.00 1.00 Velocity (ft/sec): 0.20 0.00 0.00 Computed Flow Time (minutes): 23.22 0.00 0.00 ================================================================================================ Total TOC (minutes): 23.22 ================================================================================================ -------------------- Subbasin {_}._P.4 -------------------- Page 16 1522.0 Prop Output ================================================================================================ Total TOC (minutes): 0.00 ================================================================================================ -------------------- Subbasin {_}._P.5 -------------------- ================================================================================================ Total TOC (minutes): 0.00 ================================================================================================ -------------------- Subbasin {_}._P.6 -------------------- Sheet Flow Computations ----------------------- Subarea A Subarea B Subarea C Manning's Roughness: 0.11 0.00 0.00 Flow Length (ft): 220.00 0.00 0.00 Slope (%): 3.00 0.00 0.00 2 yr, 24 hr Rainfall (in): 1.75 1.00 1.00 Velocity (ft/sec): 0.22 0.00 0.00 Computed Flow Time (minutes): 16.52 0.00 0.00 ================================================================================================ Total TOC (minutes): 16.52 ================================================================================================ -------------------- Subbasin {_}._P.7 -------------------- Page 17 1522.0 Prop Output Sheet Flow Computations ----------------------- Subarea A Subarea B Subarea C Manning's Roughness: 0.11 0.00 0.00 Flow Length (ft): 300.00 0.00 0.00 Slope (%): 12.00 0.00 0.00 2 yr, 24 hr Rainfall (in): 1.75 1.00 1.00 Velocity (ft/sec): 0.41 0.00 0.00 Computed Flow Time (minutes): 12.16 0.00 0.00 Shallow Concentrated Flow Computations -------------------------------------- Subarea A Subarea B Subarea C Flow Length (ft): 598.00 0.00 0.00 Slope (%): 5.50 0.00 0.00 Surface Type: Paved Unpaved Unpaved Velocity (ft/sec): 3.50 0.00 0.00 Computed Flow Time (minutes): 2.85 0.00 0.00 ================================================================================================ Total TOC (minutes): 15.01 ================================================================================================ *********************** Subbasin Runoff Summary *********************** --------------------------------------------------------------------------------------- Subbasin Accumulated Rainfall Total Peak Weighted Time of ID Precip Intensity Runoff Runoff Runoff Concentration in in/hr in cfs Coeff days hh:mm:ss --------------------------------------------------------------------------------------- {_}._P.1 0.73 3.92 0.62 1.17 0.850 0 00:11:09 Page 18 1522.0 Prop Output {_}._P.2 0.76 3.69 0.36 0.45 0.480 0 00:12:16 {_}._P.3 0.94 2.44 0.61 1.30 0.650 0 00:23:13 {_}._P.4 0.55 6.59 0.05 0.05 0.100 0 00:05:00 {_}._P.5 0.55 6.59 0.07 0.59 0.120 0 00:05:00 {_}._P.6 0.84 3.04 0.67 2.71 0.800 0 00:16:31 {_}._P.7 0.81 3.24 0.63 5.90 0.780 0 00:15:00 --------------------------------------------------------------------------------------- ****************** Node Depth Summary ****************** ----------------------------------------------------------------------------------------- Node Average Maximum Maximum Time of Max Total Total Retention ID Depth Depth HGL Occurrence Flooded Time Time Attained Attained Attained Volume Flooded ft ft ft days hh:mm acre-in minutes hh:mm:ss ----------------------------------------------------------------------------------------- Jun-01 0.30 0.86 50.76 0 00:15 0 0 0:00:00 Jun-02 0.26 0.74 44.34 0 00:15 0 0 0:00:00 Jun-03 0.56 0.97 55.57 0 00:15 0 0 0:00:00 Jun-04 0.14 0.39 59.39 0 00:16 0 0 0:00:00 Jun-05 0.31 0.98 55.98 0 00:15 0 0 0:00:00 Jun-06 1.38 1.39 56.43 0 00:03 0 0 0:00:00 Jun-07 2.23 2.23 61.53 0 00:00 0 0 0:00:00 Jun-08 1.75 1.78 54.28 0 00:00 0 0 0:00:00 Jun-09 1.74 1.78 50.28 0 00:01 0 0 0:00:00 Jun-10 0.04 0.15 45.35 0 00:12 0 0 0:00:00 Jun-11 0.12 0.23 51.83 0 00:23 0 0 0:00:00 Jun-12 0.17 0.31 42.31 0 00:23 0 0 0:00:00 Jun-13 0.13 0.24 46.74 0 00:23 0 0 0:00:00 Jun-20 2.23 2.23 60.40 0 00:01 0 0 0:00:00 Jun-21 1.85 1.85 58.61 0 00:02 0 0 0:00:00 Page 19 1522.0 Prop Output Jun-22 1.33 1.34 55.62 0 00:05 0 0 0:00:00 POC'A' 1.41 1.44 42.20 0 00:05 0 0 0:00:00 ***************** Node Flow Summary ***************** ------------------------------------------------------------------------------------ Node Element Maximum Peak Time of Maximum Time of Peak ID Type Lateral Inflow Peak Inflow Flooding Flooding Inflow Occurrence Overflow Occurrence cfs cfs days hh:mm cfs days hh:mm ------------------------------------------------------------------------------------ Jun-01 JUNCTION 0.00 8.32 0 00:15 0.00 Jun-02 JUNCTION 1.17 9.00 0 00:15 0.00 Jun-03 JUNCTION 0.00 8.35 0 00:15 0.00 Jun-04 JUNCTION 2.71 2.71 0 00:16 0.00 Jun-05 JUNCTION 5.90 5.90 0 00:15 0.00 Jun-06 JUNCTION 0.63 66.63 0 00:05 0.00 Jun-07 JUNCTION 66.00 66.00 0 00:00 0.00 Jun-08 JUNCTION 0.00 66.62 0 00:05 0.00 Jun-09 JUNCTION 0.00 66.61 0 00:05 0.00 Jun-10 JUNCTION 0.45 0.45 0 00:12 0.00 Jun-11 JUNCTION 1.30 1.30 0 00:23 0.00 Jun-12 JUNCTION 0.00 1.34 0 00:23 0.00 Jun-13 JUNCTION 0.00 1.30 0 00:23 0.00 Jun-20 JUNCTION 0.00 66.00 0 00:01 0.00 Jun-21 JUNCTION 0.00 66.00 0 00:02 0.00 Jun-22 JUNCTION 0.00 66.63 0 00:05 0.00 POC'A' OUTFALL 0.00 76.19 0 00:15 0.00 *********************** Page 20 1522.0 Prop Output Outfall Loading Summary *********************** ----------------------------------------------- Outfall Node ID Flow Average Peak Frequency Flow Inflow (%) cfs cfs ----------------------------------------------- POC'A' 99.39 68.23 76.19 ----------------------------------------------- System 99.39 68.23 76.19 ***************** Link Flow Summary ***************** ------------------------------------------------------------------------------------------------------------------ -------------- Link ID Element Time of Maximum Length Peak Flow Design Ratio of Ratio of Total Reported Type Peak Flow Velocity Factor during Flow Maximum Maximum Time Condition Occurrence Attained Analysis Capacity /Design Flow Surcharged days hh:mm ft/sec cfs cfs Flow Depth minutes ------------------------------------------------------------------------------------------------------------------ -------------- Link-01 CONDUIT 0 00:15 12.21 1.00 9.00 22.99 0.39 0.43 0 Calculated Link-02 CONDUIT 0 00:15 8.01 1.00 8.32 13.41 0.62 0.57 Page 21 1522.0 Prop Output 0 Calculated Link-03 CONDUIT 0 00:16 9.50 1.00 2.71 8.35 0.32 0.39 0 Calculated Link-04 CONDUIT 0 00:15 4.96 1.00 5.88 7.79 0.75 0.65 0 Calculated Link-05 CONDUIT 0 00:15 9.60 1.00 8.31 17.07 0.49 0.49 0 Calculated Link-06 CHANNEL 0 00:01 7.61 1.00 66.00 142.99 0.46 0.75 0 Calculated Link-07 CHANNEL 0 00:05 5.62 1.00 66.63 976.59 0.07 0.25 0 Calculated Link-08 CHANNEL 0 00:05 6.60 1.00 66.61 461.84 0.14 0.57 0 Calculated Link-09 CHANNEL 0 00:05 9.69 1.00 66.61 74.79 0.89 0.96 0 Calculated Link-10 CONDUIT 0 00:23 3.79 1.00 1.34 55.31 0.02 0.11 0 Calculated Link-11 CONDUIT 0 00:23 5.19 1.00 1.29 83.98 0.02 0.09 0 Calculated Link-12 CONDUIT 0 00:12 6.05 1.00 0.45 9.10 0.05 0.15 0 Calculated Link-13 CONDUIT 0 00:23 9.64 1.00 1.30 11.41 0.11 0.23 0 Calculated Link-20 CHANNEL 0 00:02 6.93 1.00 66.00 242.58 0.27 0.66 0 Calculated Link-21 CHANNEL 0 00:03 6.31 1.00 66.00 932.42 0.07 0.40 0 Calculated Link-22 CHANNEL 0 00:05 5.88 1.00 66.62 1068.75 0.06 0.28 0 Calculated Page 22 EXISTING VS. PROPOSED TIME SERIES PLOT APPENDIX D REFERENCE DRAWINGS Page intentionally left blank for double-sided printing ATTACHMENT 6 Copy of Project's Geotechnical and Groundwater Investigation Report Attach project’s geotechnical and groundwater investigation report. Refer to Appendix C.4 to determine the reporting requirements. Page intentionally left blank for double-sided printing Report Preliminary Geotechnical Investigation and Infiltration Study Bonita Glen Apartments Bonita Glen Drive, Chula Vista, California PREPARED FOR Silvergate Development, LLC 4980 N Harbor Drive, Suite 203 San Diego, CA 92106 PREPARED BY NOVA Services, Inc. 4373 Viewridge Ave, Ste. B San Diego, California 92123 NOVA Project No. 2017826 December 4, 2017 G E O T E C H N I C A L Ŷ M A T E R I A L S Ŷ S P E C I A L I N S P E C T I O N S S B E Ŷ S L B E Ŷ S C O O P 4373 Viewridge Avenue, Ste. B San Diego, CA 92123 858.292.7575 Mr. Tommy Edmunds December 4, 2017 Silvergate Development, LLC NOVA Project 2017826 4980 N Harbor Drive, Suite 203 San Diego, CA 92106 Subject: Report Preliminary Geotechnical Investigation and Infiltration Study Bonita Glen Apartments Bonita Glen Drive, Chula Vista, California Dear Mr. Edmunds: NOVA Services, Inc. (NOVA) is pleased to present herewith its report of the above-referenced geotechnical investigation. The work reported was completed by NOVA for Silvergate Development LLC in accordance with NOVA’s proposal dated October 26, 2016. NOVA appreciates the opportunity to be of continued service to Silvergate Development LLC for its developments in the San Diego region. In the meantime, should you have any questions regarding this report or other matters, please do not hesitate to contact the undersigned at (858) 292-7575. Sincerely, NOVA Services, Inc. ________________ _________________________ Wail Mokhtar Bryan Miller-Hicks, P.E., G.E. Project Manager Senior Geologist __________________________ John F. O’Brien, P.E., G.E. Principal Geotechnical Engineer Report Preliminary Geotechnical Investigation and Infiltration Study Bonita Glen Apartments, Chula Vista, California ______________________________________________________________ Table of Contents 1.0 INTRODUCTION.............................................................................................................. 1 1.1 Terms of Reference.........................................................................................................................1 1.2 Objective, Scope, and Limitations of This Work.........................................................................1 1.2.1 Objective......................................................................................................................................................1 1.2.2 Scope............................................................................................................................................................2 1.2.3 Limitations...................................................................................................................................................2 1.3 Organization of This Report..........................................................................................................3 2.0 PROJECT INFORMATION............................................................................................ 4 2.1 Location ...........................................................................................................................................4 2.2 Planned Development.....................................................................................................................4 2.2.1 Architectural.................................................................................................................................................4 2.2.2 Structural......................................................................................................................................................5 2.2.3 Stormwater BMPs........................................................................................................................................6 2.3 Below Grade Construction and Potential for Earthwork...........................................................7 2.3.1 Below Grade Construction...........................................................................................................................7 2.3.2 Potential for Earthwork................................................................................................................................7 3.0 FIELD EXPLORATION AND LABORATORY TESTING ........................................ 8 3.1 Overview..........................................................................................................................................8 3.2 Engineering Borings .......................................................................................................................9 3.2.1 General.........................................................................................................................................................9 3.2.2 Logging and Sampling.................................................................................................................................9 3.2.3 Closure.......................................................................................................................................................10 3.3 Percolation Testing .......................................................................................................................10 3.3.1 General.......................................................................................................................................................10 3.3.2 Drilling.......................................................................................................................................................10 3.3.3 Conversion to Percolation Wells................................................................................................................10 Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 Page ii of vi 3.3.4 Percolation Testing.....................................................................................................................................10 3.3.5 Closure.......................................................................................................................................................11 3.4 Geotechnical Laboratory Testing................................................................................................11 3.4.1 General.......................................................................................................................................................11 3.4.2 Compaction................................................................................................................................................11 3.4.3 Soil Gradation and Moisture......................................................................................................................11 3.4.4 R-Value......................................................................................................................................................12 3.4.5 Plasticity and Expansion Potential.............................................................................................................12 3.5 Corrosion Potential.......................................................................................................................13 4.0 SITE CONDITIONS........................................................................................................ 14 4.1 Geologic and Seismic Setting .......................................................................................................14 4.1.1 Regional.....................................................................................................................................................14 4.1.2 Site Specific ..............................................................................................................................................14 4.2 Site Specific Conditions................................................................................................................15 4.2.1 Surface .......................................................................................................................................................15 4.2.2 Subsurface..................................................................................................................................................16 4.2.3 Groundwater...............................................................................................................................................16 4.2.4 Surface Water.............................................................................................................................................16 5.0 REVIEW OF GEOLOGIC HAZARDS......................................................................... 18 5.1 Overview........................................................................................................................................18 5.2 Geologic Hazards..........................................................................................................................18 5.2.1 Strong Ground Motion...............................................................................................................................18 5.2.2 Landslide....................................................................................................................................................18 5.3 Soil Hazards...................................................................................................................................19 5.3.1 Embankment Stability................................................................................................................................19 5.3.2 Seismic.......................................................................................................................................................20 5.3.3 Expansive Soil............................................................................................................................................20 5.3.4 Hydro-Collapsible Soils.............................................................................................................................20 5.3.5 Corrosive Soils...........................................................................................................................................21 5.4 Other Hazards...............................................................................................................................21 5.4.1 Flood..........................................................................................................................................................21 5.4.2 Tsunami......................................................................................................................................................21 5.4.3 Seiche.........................................................................................................................................................22 6.0 EARTHWORK AND FOUNDATIONS........................................................................ 23 6.1 Overview........................................................................................................................................23 6.1.1 General.......................................................................................................................................................23 Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 Page iii of vi 6.1.2 Review and Surveillance............................................................................................................................23 6.2 Seismic Design Parameters ..........................................................................................................23 6.2.1 Site Class....................................................................................................................................................23 6.2.2 Seismic Design Parameters........................................................................................................................23 6.3 Corrosivity and Sulfates...............................................................................................................24 6.3.1 General.......................................................................................................................................................24 6.3.2 Metals.........................................................................................................................................................24 6.3.3 Sulfates and Concrete.................................................................................................................................25 6.3.4 Limitations.................................................................................................................................................26 6.4 Site Preparation and Earthwork.................................................................................................26 6.4.1 Establish Erosion and Sedimentation Control............................................................................................26 6.4.2 Clearing and Grubbing...............................................................................................................................26 6.4.3 Grading for Foundations............................................................................................................................26 6.4.4 Remedial Grading for Flatwork .................................................................................................................27 6.5 Shallow Foundations.....................................................................................................................27 6.5.1 Bearing Unit...............................................................................................................................................27 6.5.2 Minimum Dimensions and Reinforcing.....................................................................................................28 6.5.3 Allowable Contact Stress...........................................................................................................................28 6.5.4 Lateral Resistance ......................................................................................................................................28 6.5.5 Settlement...................................................................................................................................................28 6.5.6 Footing Construction and Inspection .........................................................................................................28 6.6 Ground Supported Slabs..............................................................................................................28 6.6.1 Conventionally Reinforced Slab-on-Grade................................................................................................28 6.6.2 Slab Setback from Slopes...........................................................................................................................29 6.6.3 Slope Maintenance.....................................................................................................................................29 6.6.4 Moisture Barrier.........................................................................................................................................29 6.7 Control of Drainage Around Structures.....................................................................................30 6.7.1 General.......................................................................................................................................................30 6.7.2 Landscaping...............................................................................................................................................30 6.7.3 Drainage.....................................................................................................................................................30 6.7.4 Surface Grades...........................................................................................................................................31 6.7.5 Backfills.....................................................................................................................................................31 6.7.6 Utilities.......................................................................................................................................................31 6.8 Retaining Walls.............................................................................................................................31 6.8.1 General.......................................................................................................................................................31 6.8.2 Shallow Foundations..................................................................................................................................31 6.8.3 Lateral Earth Pressures...............................................................................................................................32 6.8.4 Foundation Uplift.......................................................................................................................................32 6.8.5 Resistance to Lateral Loads........................................................................................................................32 6.8.6 Wall Drainage............................................................................................................................................32 6.8.7 Seismic.......................................................................................................................................................32 6.9 Elevator Pits ..................................................................................................................................33 Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 Page iv of vi 6.10 Temporary Slopes.........................................................................................................................33 7.0 STORMWATER INFILTRATION............................................................................... 34 7.1 Overview........................................................................................................................................34 7.2 Infiltration Rates...........................................................................................................................34 7.2.1 General.......................................................................................................................................................34 7.2.2 Design Infiltration Rate..............................................................................................................................34 7.3 Review of Geotechnical Feasibility Criteria...............................................................................35 7.3.1 Overview....................................................................................................................................................35 7.3.2 Soil and Geologic Conditions ....................................................................................................................35 7.3.3 Settlement and Volume Change.................................................................................................................35 7.3.4 Slope Stability............................................................................................................................................35 7.3.5 Utilities.......................................................................................................................................................36 7.3.6 Groundwater Mounding.............................................................................................................................36 7.3.7 Retaining Walls and Foundations ..............................................................................................................36 7.3.8 Other Factors..............................................................................................................................................36 7.4 Suitability of the Site for Stormwater Infiltration.....................................................................36 8.0 PAVEMENTS .................................................................................................................. 37 8.1 General...........................................................................................................................................37 8.2 Setback from Slopes......................................................................................................................37 8.3 Subgrade Preparation...................................................................................................................37 8.3.1 Rough Grading...........................................................................................................................................37 8.3.2 Proof-Rolling .............................................................................................................................................38 8.3.3 Moisture Control........................................................................................................................................38 8.3.4 Surveillance................................................................................................................................................38 8.4 Flexible Pavements........................................................................................................................38 8.5 Rigid Pavements............................................................................................................................39 8.5.1 General.......................................................................................................................................................39 8.5.2 Jointing and Reinforcement .......................................................................................................................39 9.0 REFERENCES................................................................................................................. 40 9.1 Site Specific....................................................................................................................................40 9.2 Design.............................................................................................................................................40 9.3 Geologic and Site Setting..............................................................................................................40 Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 Page v of vi List of Plates Plate 1: Subsurface Investigation Map List of Appendices Appendix A Use of this Report Appendix B Soil Exploration Logs Appendix C Records of Infiltration Testing Appendix E Laboratory Analytical Results List of Figures Figure 1-1. Vicinity Map Figure 2-1. Site Location and Limits Figure 2-2. Conceptual Planning Figure 2-3. Elevation View of the Four Level Apartment Building Figure 2-4. Proposed Storm Drain System Figure 3-1. Location of the Engineering and Percolation Test Borings Figure 4-1. Geologic Mapping of the Site Vicinity Figure 4-2. Site View from the East Along Vista Drive Figure 4-3. Alignment and Limits of the Ephemeral Stream Figure 5-1. Faulting in the Site Vicinity Figure 5-2. Flood Mapping of the Site Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 Page vi of vi List of Tables Table 3-1. Abstract of the Engineering Borings Table 3-2. Abstract of the Percolation Testing Table 3-3. Summary of the Compaction Testing, ASTM D 1557 Table 3-4. Abstract of the Soil Gradation and Moisture Content Testing Table 3-5. Summary of the Corrosivity Testing Table 6-1. Seismic Design Parameters, ASCE 7-10 Table 6-2. Summary of Corrosivity Testing of the Near Surface Soil Table 6-3. Soil Resistivity and Corrosion Potential Table 6-4. Exposure Categories and Requirements for Water-Soluble Sulfates Table 6-5. Lateral Earth Pressures Table 7-1. Infiltration Rates Determined by Percolation Testing Table 8-1. Preliminary Recommendations for Flexible Pavements Table 8-2. Recommended Concrete Requirements Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 1 1.0 INTRODUCTION 1.1 Terms of Reference This report provides the findings of a geotechnical investigation for the development now known as “Bonita Glen Apartments” located on Bonita Glen Drive in Chula Vista, California (hereafter, also referenced as ‘the site’). The work reported herein was completed by NOVA Services, Inc. (NOVA) for Silvergate Development LLC in accordance with NOVA’s proposal dated July 26, 2016. Figure 1-1 depicts the vicinity of the planned Bonita Glen Apartments. Figure 1-1. Vicinity Map 1.2 Objective, Scope, and Limitations of This Work 1.2.1 Objective The objectives of the work reported herein are threefold, as described below. 1. Objective 1, Site Characterization. Characterize the subsurface conditions within the limits of the planned Bonita Glen development (hereafter, also referenced as ‘the site’). 2. Objective 2, Geotechnical. Provide recommendations for geotechnical-related development, including foundations and earthwork. 3. Objective 3, Stormwater. Provide recommendations for development of permanent stormwater infiltration BMPs. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 2 1.2.2 Scope In order to accomplish the above objectives, NOVA undertook the task-based scope of work described below. x Task 1, Background Review. Reviewed readily available background data regarding the site area, including geotechnical reports, topographic maps, geologic data, fault maps, and preliminary development plans for the project. Preliminary architectural and civil design information was also reviewed. x Task 2, Subsurface Exploration. The exploration includes the following subtasks. o Subtask 2-1, Reconnaissance. Prior to undertaking any invasive work, NOVA conducted a site reconnaissance, including layout of the exploratory borings used to explore the subsurface conditions. Underground Service Alert was notified for underground utility mark-out services. o Subtask 2-2, Coordination. NOVA coordinated with Silvergate regarding access for fieldwork. NOVA retained a specialty subcontractor to conduct the drilling. o Subtask 2-3, Engineering Borings. A NOVA geologist directed drilling of six (6) engineering borings, including two borings located within 50 feet of proposed DMAs. o Subtask 2-4, Percolation Borings, and Testing. A NOVA geologist directed the drilling of four (4) percolation test borings located within the DMA’s. Thereafter, percolation testing was conducted in accordance with the requirements of the City of Chula Vista. x Task 3, Laboratory Testing. Laboratory testing was undertaken to address index soil characteristics and the potential that soils may be corrosive to embedded concrete or metals. x Task 4, Engineering Evaluations. The findings of Tasks 1-3 were utilized to support geotechnical and stormwater infiltration-related evaluations. x Task 5, Reporting. This report presents the findings of all work, and completes NOVA’s scope of work. The report addresses (i) development of foundation support for the separate structural elements; and (ii) the siting and design of permanent stormwater infiltration BMPs. 1.2.3 Limitations The recommendations included in this report are not final. These recommendations are developed by NOVA using judgment and opinion and based upon the limited information available from the borings. NOVA can finalize its recommendations only by observing actual subsurface conditions revealed during construction. NOVA cannot assume responsibility or liability for the report's recommendations if NOVA does not perform construction observation. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 3 This report does not address any environmental matters; including, but not limited to assessment or investigation for the presence or absence of hazardous or toxic materials in the soil, groundwater, or surface water within or beyond the site. Appendix A provides additional discussion regarding limitations and use of this report. 1.3 Organization of This Report The remainder of this report is organized as described below. x Section 2 reviews the presently available project information. x Section 3 describes the field investigation and laboratory testing. x Section 4 describes the geologic and subsurface conditions. x Section 5 reviews soil and geologic hazards that may affect the site. x Section 6 provides recommendations for earthwork and foundations. x Section 7 addresses stormwater infiltration. x Section 8 provides recommendations for pavements. x Section 9 lists the principal references used in evaluations for this report. The report is supported by four appendices. x Appendix A presents discussion regarding use of this report. x Appendix B presents logs of borings. x Appendix C provides records of percolation testing x Appendix D provides records of geotechnical laboratory testing. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 4 2.0 PROJECT INFORMATION 2.1 Location The subject property is an irregularly-shaped parcel identified as APN 570-131-11, 570-010-10, 570-140- 48 and 570-140-5, comprising about 5.3 acres of open, vacant land in the city of Chula Vista. The property is bounded by Bonita Glen Drive on the south, and Vista Drive to the east and north. Figure 2-1 depicts the location and limits of the planned development. Figure 2-1. Site Location and Limits 2.2 Planned Development 2.2.1 Architectural NOVA’s understanding of the proposed development is based on review of planning level architectural graphics (reference, Bonita Glen Apartments, Studio E Architects, Project 16124, October 17, 2017). This preliminary planning indicates the project will consist of seven residential buildings, six of which will rise to three levels, with ‘tuck under’ parking at Level 1 and dwelling units at Level 2 and Level 3. A seventh building will have three stories of residential use over one story of parking. The seven residential structures will provide an aggregate of 170 dwelling units, with the seventh, four- level structure containing 66 units. Infrastructure, consisting of landscaped areas, surface parking and a variety of amenities, will support the development. Figure 2-2 (following page) depicts conceptual planning for the layout of the planned development. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 5 Figure 2-2. Conceptual Planning (source: Studio E Architects 2017) 2.2.2 Structural Design is still in preliminary stages. As a consequence of the preliminary nature of the design, structural design has not begun. However, it is understood that design will adapt to ‘Type V-A over Type 1-A,’ allowing for development of wood framed residential units (Type V-A) atop a reinforced concrete podium (Type 1-A). Figure 2- 3 provides an elevation view of the largest of the planned structures. Figure 2-3. Elevation View of the Four Level Apartment Building (source: Studio E Architects 2017) Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 6 2.2.3 Stormwater BMPs Preliminary civil planning by Latitude 33 (reference, Preliminary Drainage Study, Bonita Glen, Bonita Glen Drive, Chula Vista, California 91910, Latitude 33 Planning & Engineering, Job 1522.00, undated) describes planning for stormwater management. The site is already drained by an ephemeral stream that runs approximately north-south through the eastern third of the property. This stream will continue to collect surface water following development. Other stormwater will be managed by utilizing biofiltration basin-type drainage management areas (‘DMAs’) for stormwater Best Management Practices (‘BMPs’). Conceptual planning locates the basins in the northwestern area of the property. Figure 2-4 depicts the planned layout of the storm drain system. Figure 2-4. Proposed Storm Drain System (source: Latitude 33 2017) Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 7 2.3 Below Grade Construction and Potential for Earthwork 2.3.1 Below Grade Construction Based upon review of the design that is currently available, there is no indication of planning for below grade construction of any scale (basements, subterranean garages, etc.). Adapting the residential structures to the existing site grades may require that small (less than 5 feet height) embankments be retained. It is, of course, understood that construction of utilities, certain elements of stormwater BMPs, and related infrastructure will require limited below grade construction. 2.3.2 Potential for Earthwork NOVA estimates that requirements for earthwork will be limited. In review of planning that is currently available, it appears that the new structures will be developed from approximately existing grade. There is will be limited requirements for cutting and filling to adapt structures and drainage to existing site grades. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 8 3.0 FIELD EXPLORATION AND LABORATORY TESTING 3.1 Overview The field exploration by NOVA was completed on November 9, 2017. The field exploration consisted of six engineering borings (referenced as B-1 through B-6) and four percolation test borings (referenced as P-1 through P-4). The borings were drilled under the surveillance of a NOVA geologist by a specialty subcontractor retained by NOVA. Figure 3-1 depicts the location of the field work. Plate 1, provided immediately following the text of this report provides a larger scale depiction of Figure 3-1. Figure 3-1. Location of the Engineering and Percolation Test Borings (source: adapted from Studio E Architects 2017) Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 9 Soil samples recovered from the engineering borings were transferred to NOVA’s geotechnical laboratory where a geotechnical engineer reviewed the soil samples and the field logs. Representative soil samples were selected and tested in NOVA’s materials laboratory to check visual classifications and to determine pertinent engineering properties. 3.2 Engineering Borings 3.2.1 General The engineering borings were advanced by a truck-mounted drilling rig utilizing hollow stem auger drilling equipment. Boring locations were determined in the field by the NOVA geologist. Elevations of the ground surface at the boring locations were estimated. Table 3-1 provides an abstract of the engineering borings. Table 3-1. Abstract of the Engineering Borings Boring Reference Approximate Ground Surface Elevation (feet, msl) Total Depth Below Ground Surface (feet) Depth to Groundwater (feet) B-1 +80 21.5 n/e B-2 +73 21.5 n/e B-3 +68 21.5 n/e B-4 +60 21.5 n/e B-5 +58 36.5 33 B-6 +55 18 n/e Notes: 1. ‘n/e’ indicates ‘groundwater not encountered’ 2. B-6 terminated at 18 feet due to refusal on dense soils 3.2.2 Logging and Sampling The borings were completed under the direction of a geologist from NOVA who directed sampling and maintained a log of the subsurface materials that were encountered. Both disturbed and relatively undisturbed samples were recovered from the borings, sampling of soils is described below. 1. The Modified California sampler (‘ring sampler’, after ASTM D 3550) was driven using a 140- pound hammer falling for 30 inches with a total penetration of 18 inches, recording blow counts for each 6 inches of penetration. 2. The Standard Penetration Test sampler (‘SPT’, after ASTM D 1586) was driven in the same manner as the ring sampler, recording blow counts in the same fashion. SPT blow counts for the final 12 inches of penetration comprise the SPT ‘N’ value, an index of soil consistency. 3. Bulk samples were recovered from the upper 5 feet of the subsurface, providing composite samples for testing of soil moisture and density relationships and corrosivity. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 10 Logs of the borings are provided in Appendix B. The group symbols for each soil type are indicated in parentheses following the soil descriptions on the logs. The stratification lines designating the interfaces between earth materials on the trench, boring logs and profiles are approximate; in-situ, the transitions may be gradual. 3.2.3 Closure Each boring was backfilled to the ground surface with bentonite chips and cuttings upon completion. The area of each boring was restored as closely as possible to its approximate condition before drilling. 3.3 Percolation Testing 3.3.1 General NOVA directed the excavation and construction of four (4) percolation test borings, following the recommendations for percolation testing presented in the City of Chula Vista BMP Design Manual. The locations of these borings are shown on Figure 3-1. 3.3.2 Drilling Borings were drilled with a truck mounted 8-inch hollow stem auger to the level of the base of planned storm water infiltration BMPs, five to six feet bgs. Field measurements were taken to confirm that the borings were excavated to approximately 8-inches in diameter. The borings were logged by a NOVA geologist, who observed and recorded exposed soil cuttings and the boring conditions. Logs of the exploratory percolation test borings are provided in Appendix B. 3.3.3 Conversion to Percolation Wells Once the test borings were drilled to the design depth, the borings were converted to percolation wells by placing an approximately 2-inch layer of ¾-inch gravel on the bottom, then extending 3-inch diameter Schedule 40 perforated PVC pipe to the ground surface. The ¾-inch gravel was used to fill the annular space around the perforated pipe to at least 12-inches below existing finish grade to minimize the potential of soil caving. 3.3.4 Percolation Testing The percolation test holes were pre-soaked before testing and immediately prior to testing. The pre-soak process consisted of filling the hole twice with water before testing. Water levels were recorded every 30 minutes for six hours (minimum of 12 readings), or until the water percolation stabilized after each reading, the water level was raised to close to the previous water level to maintain a near constant head before subsequent readings. Table 3-2 (following page) abstracts the indications of the percolation testing. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 11 Table 3-2. Abstract of the Percolation Testing Boring Approx. Elevation (feet, msl) Total Depth (feet) Approximate Percolation Test Elev. (feet, msl) Percolation Rate (in/hour)2 Subsurface Units Tested 1 P-1 +54 5 +49 0.24 Qa P-2 +50 5 +45 0.48 Qa P-3 +49 5 +44 0.72 Qa P-4 +50 5 +45 0.48 Qa Note: The referenced geologic unit is Alluvium (Qal). 3.3.5 Closure At the conclusion of the percolation testing, the upper sections of the PVC pipe were removed and the resulting holes backfilled with soil cuttings and patched to match the existing surfacing. 3.4 Geotechnical Laboratory Testing 3.4.1 General Soil samples were returned to the laboratory where a geotechnical engineer reviewed the field logs and classified each soil sample on the basis of texture and plasticity in accordance with the Unified Soil Classification System (‘USCS,’ ASTM D2487). Representative soil samples were selected and tested in NOVA’s materials laboratory to check visual classifications and to determine pertinent engineering properties. The laboratory testing program included index testing on selected soil samples. Results of the testing are presented in Appendix E. 3.4.2 Compaction Near-surface soils removed from excavations may be suitable for reuse (see Section 6 for definition of suitable soils). In order to address the potential that some soil could be replaced, compaction testing after ASTM D 1557 was undertaken to establish the moisture-density relationship of these soils. The results of the compaction testing are summarized in Table 3-3. Table 3-3. Summary of the Compaction Testing, ASTM D 1557 Boring Sample Depth (feet) Soil Description Maximum Dry Density (lb/ft3) Optimum Moisture Content (%) B-1 0 to 5 Dark brown sandy silt 122.0 9.5 B-6 0 to 5 Dark brown sandy silt 128.5 8.7 3.4.3 Soil Gradation and Moisture The visual classifications were further evaluated by performing moisture content and grain size testing. Gradation testing was performed after ASTM D422. Table 3-4 (following page) provides a summary of this testing. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 12 Table 3-4. Abstract of the Soil Gradation and Moisture Content Testing Sample Reference As Sampled Percent Finer than the U.S. No 200 Sieve Classification after ASTM D2488BoringDepth (feet) Natural Moisture (%) Dry Unit Weight (pcf) B-1 5 10 116 B-1 20 51 SM-ML B-4 10 9 113 B-4 15 35 SM B-5 5 11 116 B-5 35 22 SM B-6 2.5 9 124 B-6 7.5 50 SM-ML B-1 0 to 5 57 ML-SM B-3 15 to 20 46 SM-ML B-5 30 to 35 35 SM B-6 0 to 5 50 SM-ML P-1 0 to 5 51 ML-SM P-2 0 to 5 51 ML-SM P-3 0 to 5 49 SM-ML P-4 0 to 5 52 ML-SM Note: ‘Percent finer’ is percent by weight passing the U.S. # 200 sieve (0.074 mm), after ASTM D6913. 3.4.4 R-Value The purpose of this test is to determine the suitability of prospective subgrade soils and road aggregates for use in the pavement sections of roadways. The test is used by Caltrans for pavement design, replacing the California Bearing Ratio (CBR) test. The Resistance Value (R-value) test is a material stiffness test, demonstrating a material’s resistance to deformation as a function of the ratio of transmitted lateral pressure to applied vertical pressure. A saturated cylindrical soil sample is placed in a Hveem Stabilometer device and then compressed. The stabilometer measures the horizontal pressure that is produced while the specimen is under compression. A sample representative of soils from the upper five feet of Boring 3 was selected for this testing. Testing after ASTM D 2844 indicated an R-value of 12, a value characteristic of R-values for silty soils. Design for pavements should anticipate R ~ 12. 3.4.5 Plasticity and Expansion Potential As is noted in Section 3.4.1 a geotechnical engineer reviewed the field logs and classified each soil sample on the basis of texture and plasticity in accordance with the USCS. Based upon this review, it is the judgment of NOVA that the soils at the site are predominantly cohesionless, with no expansion potential. Based upon this judgment, no testing to determine plasticity (i.e., Atterberg Limits after ASTM D 4318) or expansion potential (i.e., Expansion Index after ASTM D 4829). Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 13 3.5 Corrosion Potential A representative sample of the near-surface soils was sent to a chemical laboratory for testing to evaluate the potential for soils to corrode embedded metals or concrete. Electrical resistivity, chloride content, and pH level are all indicators of the soil’s tendency to corrode ferrous metals. High concentrations of water-soluble sulfates can react with and damage concrete. The chemical testing was performed by Clarkson Laboratory and Supply, Inc. The results of the testing are tabulated on Table 3-5. Table 3-5. Summary of the Corrosivity Testing Parameter Units Boring 3 0 to 5 Feet pH Standard 7.8 Resistivity Ohm-cm 1100 Water Soluble Sulfate ppm 21 Water Soluble Chloride ppm 87 The indications of the above testing are discussed in more detail in Section 6. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 14 4.0 SITE CONDITIONS 4.1 Geologic and Seismic Setting 4.1.1 Regional The project area is located in the coastal portion of the Peninsular Range geomorphic province. This geomorphic province encompasses an area that extends approximately 900 miles from the Transverse Ranges and the Los Angeles Basin south to the southern tip of Baja California. The province varies in width from approximately 30 to 100 miles. This area of the Province has undergone several episodes of marine inundation and subsequent marine regression (coastline changes) throughout the last 54 million years. These events have resulted in the deposition of a thick sequence of marine and nonmarine sedimentary rocks on the basement igneous rocks of the Southern California Batholith and metamorphic rocks. Gradual emergence of the region from the sea occurred in Pleistocene time, and numerous wave-cut platforms, most of which were covered by relatively thin marine and nonmarine terrace deposits, formed as the sea receded from the land. Accelerated fluvial erosion during periods of heavy rainfall, along with the lowering of base sea level during Quaternary times, resulted in the rolling hills, mesas, and deeply incised canyons which characterize the landforms in western San Diego County. 4.1.2 Site Specific The site is situated within the coastal plain zone of the Peninsular Ranges geomorphic province. The geology of the area is controlled by both alluvial and marine influences. This plain is underlain by near- shore marine sedimentary rocks deposited at various intervals from the late-Mesozoic through Quaternary ages. The Coastal Plain increases in elevation from west to east across marine terrace surfaces uplifted during Pleistocene time. Sedimentary rocks consist of sandstones, siltstones, and claystones that were deposited during the Cretaceous, Tertiary, and Quaternary periods. Geologic units encountered at this site include alluvium and Very Old Paralic deposits. Figure 4-1 (following page) depicts the geology of the site area from which it can be seen that Very Old Paralic deposits (Qvop) are mapped to occur widely in this area of Chula Vista. The Very Old Paralic deposits are shallow marine and nonmarine (talus and slopewash) terrace deposits of Pleistocene age. The Paralics were deposited on a currently-raised 6 mile-wide wavecut platform. Soils of this unit are typically consolidated, light brown to reddish brown, clean to silty, medium- to coarse-grained sand and gravels with localized interbeds of clayey sand and sandy clay (i.e., localized back-beach lagoonal deposits). The paralics occur widely, found from the International Border to northern Carlsbad and comprising the dominant near-surface geologic formation in much of San Diego. The unit ranges to 65 feet in thickness, but is generally less than 50 feet in thickness. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 15 Figure 4-1. Geologic Mapping of the Site Vicinity 4.2 Site Specific Conditions 4.2.1 Surface As is evident by review of the aerial photo provided as Figure 2-1, the site area is currently undeveloped. Figure 4-2 (following page) provides a view of the site depicting surface conditions. As may be seen by review of this graphic, the site is cleared and covered by light grasses. The ground surface slopes downward from east to west, declining from an average elevation of about +80 feet msl at the east to about +50 feet msl at the western end. This elevation differential occurs over a distance of about 700 feet, a surface gradient of about 4%. Relatively steeper embankments rim the site to the south and east. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 16 Figure 4-2. Site View from the East Along Vista Drive 4.2.2 Subsurface The borings and test trenches indicate the site is covered by a thin veneer of fill below which lies naturally occurring dense/stiff sands and clays. For the purposes of this report, the subsurface may be considered to occur as the sequence of soil units described below. x Unit 1, Alluvium (Qa). The site is overlain by alluvium, predominantly silty and sandy mix of soils of medium dense to dense consistency. This unit ranges from 5 feet to 20 feet in thickness. x Unit 2, Paralics. The alluvium material is underlain by silty and sandy soils of the Very Old Paralic formation (Qvop). These materials are characteristically sandy and dense to very dense consistency. 4.2.3 Groundwater Static Groundwater is expected to first occur below a depth of 30 feet, below about El +25 feet msl. Perched Infiltrating storm water from prolonged wet periods can ‘perch’ atop localized zones of lower permeability soil that exist above the static groundwater level. Localized perched groundwater conditions may also develop once site development is complete and landscape irrigation commences. No perched groundwater was observed during drilling of the engineering borings. 4.2.4 Surface Water No surface water was evident on the site at the time of NOVA’s work. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 17 An ephemeral stream crosses the site, flowing approximately south to north on the western one-third of the site. The approximate alignment and limits of this drainage feature are evident on a 2010 aerial photo, reproduced as Figure 4-3. Figure 4-3. Alignment and Limits of the Ephemeral Stream NOVA did not observe any other visual evidence of seeps, springs, erosion, staining, discoloration, etc. that would indicate the occurrence of surface water. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 18 5.0 REVIEW OF GEOLOGIC HAZARDS 5.1 Overview This section provides a review of soil and geologic-related hazards common to this region of California, considering each for its potential to affect the planned development. The primary hazard identified by this review is the risk for moderate-to-severe ground shaking in response to a large-magnitude earthquake during the lifetime of the planned development. While there is no risk of liquefaction or related seismic phenomena, strong ground motion could affect the site. This circumstance is common to all civil works in this area of California. The following subsections address these and other potential soil and geologic hazards. 5.2 Geologic Hazards 5.2.1 Strong Ground Motion The site is not located within a currently designated Alquist-Priolo Earthquake Zone (Hart and Bryant, 2007). No known active faults are mapped on the site area. The nearest known active faults are faults within the Rose Canyon fault system, located approximately 3 miles west of the site. This system has the potential to be a source of strong ground motion. The seismicity of the site was evaluated utilizing a web-based analytical tool provided by the USGS. This evaluation shows the site may be subjected to a Magnitude 7 seismic event, with a corresponding risk-based Peak Ground Acceleration (PGAM) of PGAM ~ 0.43 g. No evidence of faulting was observed during NOVA’s geologic reconnaissance of the site. Geologic mapping shows a fault mapped through or very close to the site. This fault is Quaternary in age, or approximately 1 to 2 million years old. As such, it is NOVA’s professional opinion that this indicates that the mapped fault is an inactive fault. Because of the lack of known active faults on the site, the potential for surface rupture at the site is considered low. Shallow ground rupture due to shaking from distant seismic events is not considered a significant hazard, although it is a possibility at any site. Figure 5-1 (following page) maps faults in the site vicinity. 5.2.2 Landslide As used herein, ‘landslide’ describes downslope displacement of a mass of rock, soil, and/or debris by sliding, flowing, or falling. Such mass earth movements are greater than about 10 feet thick and larger than 300 feet across. Landslides typically include cohesive block glides and disrupted slumps that are formed by translation or rotation of the slope materials along one or more slip surfaces. The causes of classic landslides start with a preexisting condition- characteristically, a plane of weak soil or rock- inherent within the rock or soil mass. Thereafter, movement may be precipitated by earthquakes, wet weather, and changes to the structural or loading conditions on a slope (e.g., by erosion, cutting, filling, release of water from broken pipes, etc.). In consideration of the relatively level ground at and around the site, NOVA considers the landslide hazard at the site to be ‘negligible’ for the site and the surrounding area. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 19 Figure 5-1. Faulting in the Site Vicinity 5.3 Soil Hazards 5.3.1 Embankment Stability As used herein, ‘embankment stability’ is intended to mean the safety of localized natural or man-made embankments against failure. Unlike landslides described above, embankment stability can include smaller scale slope failures such as erosion-related washouts and more subtle, less evident processes such as soil creep. No new slopes are planned as part of the future site development. However, as is discussed in Section 4, the site is rimmed by ascending slopes to the south and east. Adaptation of the development to the slopes may require the use of retaining walls to ensure embankment stability. Similarly, the site is bounded by descending slopes to the north. Adaptation of developing infrastructure to this condition will require additional consideration/evaluation of embankment stability. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 20 5.3.2 Seismic Liquefaction ‘Liquefaction’ refers to the loss of soil strength during a seismic event. The phenomenon is observed in areas that include geologically ‘younger’ soils (i.e., soils of Holocene age), shallow water table (less than about 60 feet depth), and cohesionless (i.e., sandy and silty) soils of looser consistency. The seismic ground motions increase soil water pressures, decreasing grain-to-grain contact among the soil particles, which causes the soils to lose strength. Resistance of a soil mass to liquefaction increases with increasing density, plasticity (associated with clay-sized particles), geologic age, cementation, and stress history. The stiff/dense and geologically ‘older’ subsurface units at this site have no potential for liquefaction. Seismically Induced Settlement Apart from liquefaction, a strong seismic event can induce settlement within loose to moderately dense, unsaturated granular soils. The cohesionless sandy soils of both Unit 1 and Unit 2 are sufficiently dense and finer grained that these soils will not be prone to seismic settlement. Lateral Spreading Lateral spreading is a phenomenon in which large blocks of intact, non-liquefied soil move downslope on a liquefied soil layer. Lateral spreading is often a regional event. For lateral spreading to occur, a liquefiable soil zone must be laterally continuous and unconstrained, free to move along sloping ground. Due to the absence of a potential for liquefaction and relatively flat surrounding topography, there is no potential for lateral spreading. 5.3.3 Expansive Soil Expansive soils are characterized by their ability to undergo significant volume changes (shrinking or swelling) due to variations in moisture content¸ the magnitude of which is related to both clay content and plasticity index. These volume changes can be damaging to structures. Nationally, the annual value of real estate damage caused by expansive soils is exceeded only by that caused by termites. The encountered soils are expected to possess a low expansion potential. 5.3.4 Hydro-Collapsible Soils Hydro-collapsible soils are common in the arid climates of the western United States in specific depositional environments- principally, in areas of young alluvial fans, debris flow sediments, and loess (wind-blown sediment) deposits. These soils are characterized by low in situ density, low moisture contents, and relatively high unwetted strength. The soil grains of hydro-collapsible soils were initially deposited in a loose state (i.e., high initial ‘void ratio‘) and thereafter lightly bonded by water sensitive binding agents (e.g., clay particles, low-grade cementation, etc.). While relatively strong in a dry state, the introduction of water into these soils causes the binding agents to fail. Destruction of the bonds/binding causes relatively rapid densification and volume loss (collapse) of the soil. This change is manifested at the ground surface as subsidence or settlement. Ground settlements from the wetting can be damaging to structures and civil works. Human activities that can facilitate soil collapse include irrigation, water impoundment, changes to the natural drainage, disposal of wastewater, etc. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 21 The consistency and geologic age of the Unit 1 alluvium and the Unit 2 Paralics is such that these soils are not potentially hydro-collapsible. 5.3.5 Corrosive Soils Chemical testing of the near-surface soils indicates the soils contain low concentrations of soluble sulfates and chlorides. These soils will not be corrosive to embedded concrete and metals. Section 6 addresses this consideration in more detail. 5.4 Other Hazards 5.4.1 Flood The site is located within a FEMA-designated flood zone, FEMA Panel Nos.06073C1914G and 06073C1918G, effective on 05/16/2012. Most of the site area is designated “Zone X,” an area of minimal flood hazard. However, the northwestern portion of the site is identified to include a 0.2% annual chance of flooding. Figure 5-2 reproduces flood mapping by FEMA of the site area. Figure 5-2. Flood Mapping of the Site (source: FEMA Panel Nos.06073C1914G and 06073C1918G, effective on 05/16/2012) 5.4.2 Tsunami Tsunami describes a series of fast-moving, long period ocean waves caused by earthquakes or volcanic eruptions. The California Geological Survey Tsunami Inundation Map, National City Quadrangle (2009, show that the site is not within a tsunami inundation area. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 22 5.4.3 Seiche Seiches are standing waves that develop in an enclosed or partially enclosed body of water such as lakes or reservoirs. Harbors or inlets can also develop seiches. Most commonly caused by strong winds and rapid atmospheric pressure changes, seiches can be affected by seismic events and tsunamis. The site is not located near a body of water that could generate a seiche. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 23 6.0 EARTHWORK AND FOUNDATIONS 6.1 Overview 6.1.1 General Based upon the indications of the field and laboratory data developed for this investigation, as well as review of previously developed subsurface information, it is the opinion of NOVA that the site is suitable for development of the planned structure on shallow foundations provided the geotechnical recommendations described herein are followed. As is discussed in Section 5, the planned structures may experience strong ground motions associated with a large magnitude earthquake. This hazard is common to all civil development in this area of California. Section 6.2 addresses seismic design parameters. 6.1.2 Review and Surveillance The subsections following provide geotechnical recommendations for the planned development as it is now understood. It is intended that these recommendations provide sufficient geotechnical information to develop the project in general accordance with 2016 California Building Code (CBC) requirements. NOVA should be given the opportunity to review the grading plan, foundation plan, and geotechnical- related specifications as they become available to confirm that the recommendations presented in this report have been incorporated into the plans prepared for the project. All earthwork related to site and foundation preparation should be completed under the observation of NOVA. 6.2 Seismic Design Parameters 6.2.1 Site Class The site-specific data used to determine the Site Class typically includes borings drilled to refusal materials to determine Standard Penetration resistances (N-values). The depth of soil information available for this site is limited, such that the site is classified as Site Class D per ASCE 7 (Table 20.3-1). 6.2.2 Seismic Design Parameters Table 6-1 (following page) provides seismic design parameters for the site in accordance with 2016 CBC and mapped spectral acceleration parameters. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 24 Table 6-1. Seismic Design Parameters, ASCE 7-10 Parameter Value Site Soil Class D Site Latitude (decimal degrees)32.64649 Site Longitude (decimal degrees)-117.06346 Site Coefficient, Fa 1.124 Site Coefficient, Fv 1.684 Mapped Short Period Spectral Acceleration, SS 0.940 g Mapped One-Second Period Spectral Acceleration, S1 0.358 g Short Period Spectral Acceleration Adjusted For Site Class, SMS 1.057 g One-Second Period Spectral Acceleration Adjusted For Site Class, SM1 0.603 g Design Short Period Spectral Acceleration, SDS 0.705 g Design One-Second Period Spectral Acceleration, SD1 0.402 g Source: U.S. Seismic Design Maps, found at http://earthquake.usgs.gov/designmaps/us/application.php 6.3 Corrosivity and Sulfates 6.3.1 General Electrical resistivity, chloride content, and pH level are all indicators of the soil’s tendency to corrode ferrous metals. These chemical tests were performed on a representative sample of the near-surface soils by Clarkson Laboratory and Supply, Inc. Records of this testing are provided in Appendix E. The results of the testing are provided in Section 3 and again tabulated on Table 6-2. Table 6-2. Summary of Corrosivity Testing of the Near Surface Soil Parameter Units Value pH standard unit 7.8 Resistivity Ohm-cm 1100 Water Soluble Chloride ppm 21 Water Soluble Sulfate ppm 87 6.3.2 Metals Caltrans considers a soil to be corrosive if one or more of the following conditions exist for representative soil and/or water samples taken at the site: x chloride concentration is 500 parts per million (ppm) or greater; x sulfate concentration is 2,000 ppm (0.2%) or greater; or, x the pH is 5.5 or less. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 25 Based on the Caltrans criteria, the on-site soils would not be considered corrosive to buried metals. Appendix E provides records of the chemical testing that include estimates of the life expectancy of buried metal culverts of varying gauge. In addition to the above parameters, the risk of soil corrosivity buried metals is considered by GHWHUPLQDWLRQRIHOHFWULFDOUHVLVWLYLW\ȡ6RLOUHVLVWLYLW\PD\EHXVHGWRH[SUHVVWKHFRUURVLYLW\RIVRLO only in unsaturated soils. Corrosion of buried metal is an electrochemical process in which the amount of metal loss due to corrosion is directly proportional to the flow of DC electrical current from the metal into the soil. As the resistivity of the soil decreases, the corrosivity generally increases. A common qualitative correlation (cited in Romanoff 1989, NACE 2007) between soil resistivity and corrosivity to ferrous metals is tabulated below. Table 6-3. Soil Resistivity and Corrosion Potential Minimum Soil Resistivity (ȍ-cm) Qualitative Corrosion Potential 0 to 2,000 Severe 2,000 to 10,000 Moderate 10,000 to 30,000 Mild Over 30,000 Not Likely Despite the relatively benign environment for corrosivity indicated by pH and water-soluble chlorides, the resistivity testing suggests that design should consider that the soils may be moderately corrosive to embedded ferrous metals. Typical recommendations for mitigation of such corrosion potential in embedded ferrous metals include: x a high-quality protective coating such as an 18-mil plastic tape, extruded polyethylene, coal tar enamel, or Portland cement mortar; x electrical isolation from above grade ferrous metals and other dissimilar metals by means of dielectric fittings in utilities and exposed metal structures breaking grade; and, x steel and wire reinforcement within concrete having contact with the site soils should have at least 2 inches of concrete cover. If extremely sensitive ferrous metals are expected to be placed in contact with the site soils, it may be desirable to consult a corrosion specialist regarding choosing the construction materials and/or protection design for the objects of concern. 6.3.3 Sulfates and Concrete The soil sample tested in this evaluation indicated water-soluble sulfate (SO4) content of 87 parts per million (‘ppm,’ 0.009 % by weight). The American Concrete Institute (ACI) 318-08 considers soil with this concentration of SO4 to have no potential to for sulfate attack to embedded concrete (i.e., Exposure Class ‘S0’). Table 6-4 (following page) reproduces the ACI guidance. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 26 Table 6-4. Exposure Categories and Requirements for Water-Soluble Sulfates Exposure Category Class Water-Soluble Sulfate (SO4) In Soil (percent by weight) Cement Type (ASTM C150) Max. Water- Cement Ratio Min. f’c (psi) Not Applicable S0 SO4 < 0.10 - - - Moderate S1 624 < 0.20 II 0.50 4,000 Severe S2 624 V 0.45 4,500 Very severe S3 SO4 > 2.0 V + pozzolan 0.45 4,500 Adapted from: ACI 318-08, Building Code Requirements for Structural Concrete 6.3.4 Limitations Testing to determine several chemical parameters that indicate a potential for soils to be corrosive to construction materials are traditionally completed by the Geotechnical Engineer, comparing test results with a variety of indices regarding corrosion potential. Like most geotechnical consultants, NOVA does not practice in the field of corrosion protection, since this is not specifically a geotechnical issue. Should you require more information, a specialty corrosion consultant should be retained to address these issues. 6.4 Site Preparation and Earthwork 6.4.1 Establish Erosion and Sedimentation Control Construction-related erosion and sedimentation must be controlled in accordance with Best Management Practices and City of San Diego requirements. These controls should be established at the outset of site disturbance. 6.4.2 Clearing and Grubbing Before proceeding with construction, all vegetation, root systems, topsoil, refuse and other deleterious nonsoil materials should be stripped from construction areas. Underground utilities within the footprint of the proposed structures should be grouted in place or removed. Clearing, include the removal of any abandoned utilities, should be extended a minimum of 5 feet beyond the building and pavement limits. Stripped materials consisting of vegetation and organic materials should be wasted from the site, or used in landscaping non-structural areas 6.4.3 Grading for Foundations Foundations- either ground supported slabs or footings- may be supported at grade on Unit 1 alluvium or Unit 2 paralics prepared as described in this section. Preparation of the subgrade for ground supported slabs should include the step-wise series of actions described below. 1. Excavation. Soils should be excavated to a minimum of five feet below finish pad grade or three feet below the bottom of footings, whichever is greater. The removals should extend to at least three feet laterally beyond the structure footprint. The excavated soils should be staged near the excavation for moisture conditioning and subsequent reuse. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 27 2. Redensification/Proof Rolling. Prior to replacement, the soils disturbed by excavation should be examined to identify any localized soft, yielding or otherwise unsuitable materials by a Geotechnical Engineer from NOVA. Areas at the bottom of the removal area that are disturbed by excavation should be re-densified to 90% relative compaction after ASTM D1557 (the ‘modified Proctor’). Thereafter, the area should be proof rolled with a heavily loaded wheeled vehicle (for example, a loaded dump truck) to identify any remaining loose areas. 3. Soil Replacement. Excavated soils that are free of organics may be replaced following moisture conditioning to at least 2% of the optimum moisture content then recompacted to at least 90% relative compaction after ASTM D1557 (the ‘Modified Proctor’). The moisture conditioned soil should be replaced in loose lifts then compacted by equipment suitable for the lift thickness and soil type. The loose lifts of soil should not exceed 10-inches. 4. Select Replacement Soil. In the event that the excavated soils prove unsuitable for use or a shortage of these soils occurs, the soil replacement may be completed by use of a Select Fill. Such soil should consist of a well-graded, low expansivity soil (EI < 50), with at least 40% fines and no particle size greater than 2”. Most of Unit 1 and Unit 2 soil now found on-site meet these criteria. The Select Fill should be moisture-conditioned to at least 2 percent over the optimum moisture content and densified to at least 90% relative compaction after ASTM D1557. The Select Fill should be placed in loose lifts, then compacted by equipment suitable for the lift thickness and soil type. The loose lifts of soil should not exceed 10-inches. 5. Timely Foundation Construction. Foundations should be constructed as soon as possible following subgrade approval. The Contractor should be responsible for maintaining the subgrade in its approved condition (i.e., free of water, debris, etc.) until the foundation is constructed. 6.4.4 Remedial Grading for Flatwork Non-structural areas outside of building pads that include sidewalks and other flatwork, etc., should be over-excavated a minimum of 24-inches below existing grade or finished subgrade, whichever is deeper, and be replaced with either moisture conditioned Unit 1 soil or imported Select Fill. The bottom of the removal area should be re-densified to 90% relative compaction after ASTM D1557 (the ‘modified Proctor’). Depending on the observed condition of the existing soils, deeper over-excavation may be required in some areas. The over-excavation should extend beyond the proposed improvements a horizontal distance of at least two feet. 6.5 Shallow Foundations 6.5.1 Bearing Unit Spread or continuous footings can be used to support the new structures. These foundations should bear on compacted fill soils. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 28 6.5.2 Minimum Dimensions and Reinforcing Continuous footings should be at least 24 inches wide and have a minimum embedment of 24 inches below lowest adjacent grade. Isolated square or rectangular footings should be a minimum of 36 inches wide, embedded at least 24 inches below surrounding grade. It is recommended that all foundation elements, including any grade beams, be reinforced top and bottom. The actual reinforcement should be designed by the Structural Engineer. 6.5.3 Allowable Contact Stress Continuous and isolated footings constructed as described in the preceding sections may be designed using an allowable (net) contact stress of 2,500 pounds per square foot (psf). An allowable increase of 500 psf for each additional 12 inches in depth may be utilized, if desired. In no case should the maximum allowable contact stress should be greater than 4,000 psf. The maximum bearing value applies to combined dead and sustained live loads (DL + LL). The allowable bearing pressure may be increased by one-third when considering transient live loads, including seismic and wind forces. 6.5.4 Lateral Resistance Resistance to lateral loads will be provided by a combination of (i) friction between the soils and foundation interface; and, (ii) passive pressure acting against the vertical portion of the footings. Passive pressure may be calculated at 250 psf per foot of depth. A frictional coefficient of 0.35 may be used. No reduction is necessary when combining frictional and passive resistance. 6.5.5 Settlement Structure supported on shallow foundations as recommended above will settle on the order of 0.5 inch or less, with about 80% of this settlement occurring during the construction period. The differential settlement between adjacent columns is estimated on the order of ½ inch over a horizontal distance of 40 feet. The estimated seismic settlement (on the order of a ½ inch or less, as is discussed in Section 5) would occur in addition to this movement. 6.5.6 Footing Construction and Inspection Foundation excavations be cleaned of loose material and observed by a qualified Geotechnical Engineer or Engineering Geologist prior to placing steel or concrete to verify soil conditions exposed at the base of the excavations. 6.6 Ground Supported Slabs 6.6.1 Conventionally Reinforced Slab-on-Grade Conventionally reinforced on-grade concrete slabs may be designed using a modulus of subgrade reaction of 80 pounds per cubic inch (80 pci) provided the subgrade is prepared as described in Section 6.4. The actual slab thickness and reinforcement should be designed by the Structural Engineer. NOVA recommends the slab be a minimum 5 inches thick, reinforced by at least #3 bars placed at 16 inches on Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 29 center each way within the middle third of the slabs by supporting the steel on chairs or concrete blocks ("dobies"). Designed as described above, slab foundations will settle less than ¾ inch maximum with angular distortion due to differential settlement of unequally loaded areas less than one in 400. About 80% of foundation movement will occur during construction, such that post-construction settlement should be small enough to be imperceptible. Despite the expected low building movements, minor cracking of slab concrete after curing due to drying and shrinkage is normal and can occur. Cracking is aggravated by a variety of factors, including high water/cement ratio, high concrete temperature at the time of placement, small nominal aggregate size, and rapid moisture loss due during curing. The use of low-slump concrete or low water/cement ratios can reduce the potential for shrinkage cracking. To reduce the potential for excessive cracking, concrete slabs-on-grade should be provided with construction or ‘weakened plane’ joints at frequent intervals. Joints should be laid out to form approximately square panels. 6.6.2 Slab Setback from Slopes Descending slopes bound the site to the north, locally as steep as about 2.5:1 (H:V). In review of aerial photographs of the site dating to 1994, NOVA observed no indications of instability of the embankments in this area. Foundations for the apartment structures should be set back from descending slopes as described below: x a minimum of 5 feet from the crest of any descending slope 4:1 (H:V) or flatter; and x a minimum of 10 feet from the crest of any descending slope steeper than 4:1 (H:V). 6.6.3 Slope Maintenance The existing site slopes will be stable, but only with proper maintenance. Design should take care to not change the surface water environment in or around the drainage canyon. This should include care to control surface water drainage over the slopes and to vegetate slopes to limit erosion. Absent such protection, surficial instability or "sloughing" and “rilling erosion” will occur. If such smaller-scale losses of ground occur repairs should be affected to avoid larger scale loss of ground. 6.6.4 Moisture Barrier Industry Design Guidance NOVA recommends that any moisture barrier be designed in accordance with ACI Publication 302.1R-15, “Guide to Concrete Floor and Slab Construction.” Capillary Break and Vapor Membrane Ground supported slabs that support moisture-sensitive floor coverings or equipment may be protected by an underslab moisture barrier. Such barriers normally include two components, as described below 1. Capillary Break. A “capillary break” consisting of a 4-inch thick layer of compacted, well-graded gravel or crushed stone should be placed below the floor slab. This porous fill should be clean coarse sand or sound, durable gravel with not more than 5 percent coarser than the 1-inch sieve or more than 10 Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 30 percent finer than the No. 4 sieve, such as AASHTO Coarse Aggregate No. 57. 2. Vapor Membrane. A minimum 15-mil polyethylene membrane, or similarly- rated vapor barrier, should be placed over the porous fill to preclude floor dampness. Membranes set below floor slabs should be rugged enough to withstand construction. NOVA recommends that a minimum 15 mil low permeance vapor membrane be used. For example, Carlisle-CCW produces the Blackline 400® underslab, vapor and air barrier, a 15-mil low-density polyethylene (LDPE) rated at 0.012 perms after ASTM E 96. Limitations of This recommendation Recommendation for moisture barriers are traditionally included with geotechnical foundation recommendations, though these requirements are primarily the responsibility of the Structural Engineer or Architect. NOVA does not practice in the field of moisture vapor transmission evaluation, since this is not specifically a geotechnical issue. A specialty consultant would provide recommendations for mitigation of potential adverse impact of moisture vapor transmission on various components of the structures, as deemed appropriate. 6.7 Control of Drainage Around Structures 6.7.1 General Geotechnical, civil, structural, architectural and landscaping design for the areas around foundations must be undertaken with a view to the maintenance of an environment that encourages constant moisture conditions in the soils following construction. Roof and surface drainage, landscaping, and utility connections must be designed to limit infiltration and/or releases of moisture beneath or around structures. This care should, at a minimum, include the actions described in the following subsections. 6.7.2 Landscaping Landscaping adjacent to the structures should be limited. No new trees should be planted. If used, trees should be planted the greater of (i) 15 feet away from foundations; or (ii) 1.5 times its mature height away from foundations. Do not plant flowers or shrubs closer than five (5) feet from foundations. Planters and other surface features which could retain water in areas adjacent to the buildings should be sealed or eliminated. Sprinkler systems should not be installed within 5 feet of foundations or floor slabs. If trees are planted at locations that do not conform with the above, this action would be undertaken at the Designer’s/Owner’s sole risk. In such an event, the risk of such planting can perhaps be limited by utilizing root barriers, drought-resistant trees (to limit the need for watering) or trees with relatively shallower root systems. 6.7.3 Drainage Rainfall to roofs should be collected in gutters and discharged in a controlled manner through downspouts designed to drain away from foundations. Downspouts, roof drains or scuppers should discharge into splash blocks to slabs or paving sloped away from buildings. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 31 6.7.4 Surface Grades In areas where sidewalks or paving do not immediately adjoin the structure, protective slopes should be provided with a minimum grade of approximately 3 percent for at least 10 feet from perimeter walls. A minimum gradient of 1 percent is recommended in hardscape areas. In earth areas, a minimum gradient of 5 percent away from the structure for a distance of at least 10 feet should be provided. Earth swales should have a minimum gradient of 2 percent. Storm water should be directed to approved drainage facilities. Proper surface and subsurface drainage will be required to minimize the potential for surface water to seep to the level of the bearing soils under the foundations, pavements, and flatwork. 6.7.5 Backfills In order to reduce the possibility of moisture infiltration, backfill against foundation elements, exterior walls, and in utility and sprinkler line trenches should be with well compacted, non-expansive, low permeability soil that is free of all construction debris. 6.7.6 Utilities Design for Differential Movement Underground piping within or near structures should be designed with flexible couplings to accommodate both ground and slab movement, so that minor deviations in alignment do not result in breakage or distress. Utility knockouts should be oversized to accommodate the potential for differential movements. Backfill Above Utilities. Excavations for utility lines which extend under or near structural areas should be properly backfilled and compacted. Utilities should be bedded and backfilled with approved granular soil to a depth of at least one foot over the pipe. This backfill should be uniformly watered and compacted to a firm condition for pipe support. The remainder of the backfill should be low permeability clayey soils, moisture-conditioned and compacted to at least 90%. 6.8 Retaining Walls 6.8.1 General As is discussed in Section 2, only conceptual design information is currently available. Review of this information indicates that smaller retaining walls may be employed near ascending slopes. The following subsections provide guidance for design of cantilevered retaining walls should planning change and such retaining structures be employed. 6.8.2 Shallow Foundations Retaining walls should be developed on ground prepared in accordance with the criteria provided in Section 6.4. Continuous shallow foundations may be designed in accordance with the criteria provided in Section 6.5. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 32 6.8.3 Lateral Earth Pressures Design may include smaller (perhaps 6 feet to 10 feet tall) cantilevered, conventionally reinforced concrete retaining walls. This section provides recommendations for wall pressures for those walls. Lateral earth pressures for wall design are provided on Table 6-5 (following page) as equivalent fluid weights, in psf/foot of wall height or pounds per cubic foot (pcf). These values do not contain a factor of safety. Table 6-5. Lateral Earth Pressures Loading Condition Equivalent Fluid Density (pcf) for Approved ‘Native’ Backfill Notes A, B Level Backfill 2:1 Backfill Sloping Upwards Active (wall movement allowed) 35 60 “At Rest” (no wall movement) 65 100 ‘Passive” (wall movement toward the soils) 260 220 Note A: ‘native’ means site-sourced soil with EI < 50 after ASTM D4546. Note B: assumes wall includes appropriate drainage. 6.8.4 Foundation Uplift A soil unit weight of 125 pcf may be assumed for calculating the weight of soil over the wall footing. 6.8.5 Resistance to Lateral Loads Lateral loads to wall foundations will be resisted by a combination of frictional and passive resistance as described below. x Frictional Resistance. A coefficient of friction of 0.35 between the soil and base of the footing. x Passive Resistance. Passive soil pressure against the face of footings or shear keys will accumulate at an equivalent fluid weight of 250 pounds per cubic foot (pcf). The upper 12 inches of material in areas not protected by floor slabs or pavement should not be included in calculations of passive resistance. 6.8.6 Wall Drainage The above recommendations assume a wall drainage panel or a properly compacted granular free- draining backfill material (EI <50). The use of drainage openings through the base of the wall (weep holes) is not recommended where the seepage could be a nuisance or otherwise adversely affect the property adjacent to the base of the wall. 6.8.7 Seismic The lateral seismic pressure acting on a cantilevered retaining wall should be applied as an inverted triangle with a magnitude of 11H, where H is the free height of the wall. The resultant dynamic thrust Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 33 acts at a distance of 0.6H above the base of the wall. This equation applies to level backfill and walls that retain no more than 15 feet of soil. 6.9 Elevator Pits Though detailed planning is not available, it is possible that structures may include elevators, such that elevator pits may be necessary. Walls for an elevator pit should be designed in accordance with the recommendations provided in Section 6.7 for retaining walls. The elevator slab and related retaining wall footings will derive support from the formational soils that will be exposed in an excavation for the elevator pit. Design for the elevator pit walls should add care that considers the circumstances and conditions described below. 1. Wall Yield. NOVA expects that proper function of the elevator pit should not allow yielding of the elevator pit walls. As such, walls should be designed to resist ‘at rest’ lateral soil pressures plus the surcharge of any structures or foundations surrounding the elevator pit. 2. Construction. By virtue of a usual location near the center of the structure, the need for special equipment, and the likelihood that elevator pit construction will precede much of the construction around it, design of elevator pit walls should include consideration for surcharge conditions that will occur during construction. Such conditions may include, but not be limited to, surcharges from vehicle traffic and sloping ground above and around the walls. 3. Moisture. Consideration should be given to passive side waterproofing or damp proofing to prevent moisture accumulation inside the elevator pit. 4. Piston. If the elevator pit includes a plunger-type elevator piston, a deeper drilled excavation may be required. NOVA should be consulted regarding recommendations for development of a plunger-type elevator piston. 6.10 Temporary Slopes Temporary slopes may be required for excavations during grading. All temporary excavations should comply with local safety ordinances. The safety of all excavations is solely the responsibility of the Contractor and should be evaluated during construction as the excavation progresses. Based on the data interpreted from the borings, the design of temporary slopes may assume California Occupational Safety and Health Administration (Cal/OSHA) Soil Type C for planning purposes. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 34 7.0 STORMWATER INFILTRATION 7.1 Overview Based upon the indications of the field exploration and laboratory testing reported herein, NOVA has evaluated the site as abstracted below after guidance contained in the County of San Diego BMP Design Manual (hereafter, ‘the BMP Manual’), which is been adopted by the City of Chula Vista. Section 3.3 provides a description of the field work undertaken to complete the testing. Figure 3-1 depicts the location of the testing. This section provides the results of that testing and related recommendations for management of stormwater in conformance with the BMP Manual. The discussion provides NOVA’s assessment of the feasibility of stormwater infiltration BMPs utilizing the information developed by the field exploration described in Section 3, as well as other elements of the site assessment. 7.2 Infiltration Rates 7.2.1 General The percolation rate of a soil profile is not the same as its infiltration rate (‘I’). Therefore, the measured/calculated field percolation rate was converted to an estimated infiltration rate utilizing the Porchet Method in accordance with guidance contained in the BMP Manual. Table 7-1 provides a summary of the infiltration rates determined by the percolation testing. Table 7-1. Infiltration Rates Determined by Percolation Testing Boring Approximate Ground Elevation (feet, msl) Depth of Test (feet) Approximate Test Elevation (feet, msl) Infiltration Rate (inches/hour) Design Infiltration Rate (in/hour, F=2*) P-1 +54 5 +49 0.00 0.00 P-2 +50 5 +45 0.01 0.00 P-3 +49 5 +44 0.01 0.01 P-4 +50 5 +45 0.01 0.00 Notes: (1) ‘F’ indicates ‘Factor of Safety’ (2) elevations are approximate. 7.2.2 Design Infiltration Rate In consideration of the nature and variability of subsurface materials, as well as the natural tendency of infiltration structures to become less efficient with time, the infiltration rates measured in the testing should be modified to use at least a factor of safety (F) of F=2 for preliminary design purposes. As may be seen by review of Table 7-1, the design basis infiltration rates range from I = 0.00 to I = 0.01 inches per hour for the four areas, using a preliminary F = 2. In consideration of the natural variability of the near-surface alluvium, NOVA recommends a design of I = 0.00 inches/hour. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 35 7.3 Review of Geotechnical Feasibility Criteria 7.3.1 Overview Section C.2 of Appendix C of the BMP Manual provides seven factors should be considered by the project geotechnical professional while assessing the feasibility of infiltration related to geotechnical conditions. These factors are listed below x C.2.1 Soil and Geologic Conditions x C.2.2 Settlement and Volume Change x C.2.3 Slope Stability x C.2.4 Utility Considerations x C.2.5 Groundwater Mounding x C.2.6 Retaining Walls and Foundations x C.2.7 Other Factors The above geotechnical feasibility criteria are reviewed in the following subsections. 7.3.2 Soil and Geologic Conditions The engineering borings and percolation tests borings completed for this assessment disclose the sequence of artificial fill and rock described below. x Unit 1, Alluvium (Qa). The site is overlain by alluvium, predominantly silty and sandy mix of soils of medium dense to dense consistency. This unit ranges from 5 feet to 20 feet in thickness. x Unit 2, Paralics. The alluvium material is underlain by silty and sandy soils of the Very Old Paralic formation (Qvop). These materials are characteristically sandy dense to very dense consistency. The finer grained Unit 1 alluvium may be expected to be of lower permeability. This is expectation was confirmed by the percolation testing reported in Table 7-1. 7.3.3 Settlement and Volume Change The soils at the tested infiltration locations susceptible to settlement and/or volume change when saturated considering the very low infiltration rate and very stiff underlying formation. Measures can be taken to possibly mitigate this problem with the implementation of impermeable liners. 7.3.4 Slope Stability The periphery of the site (to the south and east) includes several areas with slopes steeper than 25%. Stormwater infiltration BMPs should not be located within 50 feet of such slopes. Because the proposed development is still within the preliminary design stage, NOVA is not aware of any planning to locate stormwater infiltration BMPs within 25 feet of slopes steeper than 25% (i.e., slopes steeper than 4H: 1V). Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 36 7.3.5 Utilities Stormwater infiltration BMPs should not be sited within 10 feet of underground utilities. Because the proposed development is still within the preliminary design stage, NOVA is not aware of any utility trenches within 10 feet of the locations of perspective BMPs. Accordingly, NOVA sees no constraint to the feasibility of stormwater BMPs by this consideration. 7.3.6 Groundwater Mounding Stormwater infiltration can result in damaging ground water mounding during wet periods. Mounded water could be damaging to utilities, development infrastructure (pavements, flat work, etc.) and building foundations. As is discussed in Sections 7.2 and 7.3, the infiltration testing reported herein indicates that vertical infiltration rates are low, averaging I = 0.00 inches/hour across the site. Implementation of stormwater infiltration BMPs could result in groundwater mounding near BMPs. 7.3.7 Retaining Walls and Foundations The BMP Manual recommends that stormwater infiltration BMPs be sited a minimum 10 feet from the retaining walls and foundations. Infiltration in close proximity to retaining walls and foundations can be affected by increased water infiltration and result of potential increases in lateral pressures and reductions in soil strength. Sited as such, BMPs will not be a hazard to structures. 7.3.8 Other Factors NOVA knows of no other geotechnical factors that could affect stormwater infiltration BMPs. 7.4 Suitability of the Site for Stormwater Infiltration It is the judgment of NOVA that the site is not suitable for stormwater infiltration BMPs. 1. Low Design Infiltration Rate. The design infiltration rate determined from the site-specific percolation testing yielded negligible infiltration rates. The geologic conditions do not allow for infiltration in any appreciable amount. 2. Widespread Low Permeability Soil. The site is underlain by the unit 2 soils known to be of low permeability and higher densities. This increases the geotechnical hazards for infiltration into the unit 1 soils. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 37 8.0 PAVEMENTS 8.1 General Similar to the requirements for control of moisture beneath floor slabs and flatwork, control of surface drainage is important to the design and construction of pavements for this site. Moisture must be controlled in the Unit 1 alluvium. Moreover, where standing water develops either on the pavement surface or within the base course- softening of the subgrade and other problems related to the deterioration of the pavement can be expected. Furthermore, good drainage should minimize the risk of the subgrade materials becoming saturated and weakened over a long period of time. The following recommendations should be considered to limit the amount of excess moisture, which can reach the subgrade soils: x maintain surface gradients at a minimum 2% grade away from the pavements; x compact utility trenches for landscaped areas to the same criteria as the pavement subgrade; x seal all landscaped areas in or adjacent to pavements to minimize or prevent moisture migration to subgrade soils; x planters should not be located next to pavements (otherwise, subdrains should be used to drain the planter to appropriate outlets); x place compacted backfill against the exterior side of curb and gutter; and, x concrete curbs bordering landscaped areas should have a deepened edge to provide a cutoff for moisture flow beneath pavements (generally, the edge of the curb can be extended an additional twelve inches below the base of the curb). Preventative maintenance should be planned and provided for. Preventative maintenance activities are intended to slow the rate of pavement deterioration and to preserve the pavement investment. Preventative maintenance consists of both localized maintenance (e.g. crack sealing and patching) and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first priority when implementing a planned pavement maintenance program and provides the highest return on investment for pavements. 8.2 Setback from Slopes Pavements should be set back a minimum of 10 feet from the crest of any descending slope steeper than 4:1 (H:V). Pavements should be set back a minimum of 5 feet from the crest of slopes 4:1 (H:V) or flatter. 8.3 Subgrade Preparation 8.3.1 Rough Grading Grading for paved areas should be as described in Section 6.3, removing and replacing the Unit 1 alluvium to a depth of two feet. The surface of the Unit 1 soils disturbed by excavation should be moisture conditioned and re-densified. Thereafter, this unit should be proof rolled to make sure no soft areas exist. Following proof rolling, the Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 38 excavated soils should be moisture conditioned to at least 2% above the optimum moisture content and replaced to at least 95% relative compaction after ASTM D 1557 (the ‘modified Proctor’). Replacement filling should be done in lifts (i) not to exceed 10-inches thickness; or, (ii) the ability of the compaction equipment employed to densified through a complete lift, whichever is less. 8.3.2 Proof-Rolling After the completion of compaction/densification, areas to receive pavements should be proof-rolled. A loaded dump truck or similar should be used to aid in identifying localized soft or unsuitable material. Any soft or unsuitable materials encountered during this proof-rolling should be removed, replaced with an approved backfill, and compacted. The Geotechnical Engineer can provide alternative options such as using geogrid and/or geotextile to stabilize the subgrade at the time of construction, if necessary. 8.3.3 Moisture Control Construction should be managed such that preparation of the subgrade immediately precedes placement of the base course. Proper drainage of the paved areas should be provided to reduce moisture infiltration to the subgrade. 8.3.4 Surveillance The preparation of roadway and parking area subgrades should be observed on a full-time basis by a representative of NOVA to confirm that any unsuitable materials have been removed and that the subgrade is suitable for support of the proposed driveways and parking areas. 8.4 Flexible Pavements The structural design of flexible pavement depends primarily on anticipated traffic conditions, subgrade soils, and construction materials. Table 8.1 provides preliminary flexible pavement sections using an R- value of 12. Table 8-1. Preliminary Pavement Sections, R = 12 Area Traffic Index Asphalt Thickness (inches) Base Thickness (inches) Passenger Car Driveways 5.0 39 4 6.5 Heavy Duty Driveways 6.0 3 12.5 4 10.5 1. The above sections assume properly prepared subgrade consisting of at least 12 inches of subgrade compacted to a minimum of 95% relative compaction after ASTM D1557, with EI <50. 2. The aggregate base materials should be placed at a minimum relative compaction of 95%. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 39 8.5 Rigid Pavements 8.5.1 General Concrete pavement sections should be developed in the same manner as undertaken for pavements: removal of the upper 2 feet of the Unit 1 soils and replacement of that material in an engineered manner as described in Section 8.3.1. Concrete pavement sections consisting of 6 inches of Portland cement concrete over a base course of 6 inches and a properly prepared subgrade support a wide range of traffic indices. Where rigid pavements are used, the concrete should be obtained from an approved mix design with the minimum properties of Table 8-2. Table 8-2. Recommended Concrete Requirements Property Recommended Requirement Compressive Strength @ 28 days 3,250 psi minimum Modulus of Rupture @ 28 days 700 minimum Strength Requirements ASTM C94 Minimum Cement Content 5.5 sacks/cu. yd. Cement Type Type I Portland Concrete Aggregate ASTM C33 and CalTrans Section 703 Aggregate Size 1 inch maximum Maximum Water Content 0.50 lb/lb of cement Maximum Allowable Slump 4 inches 8.5.2 Jointing and Reinforcement Longitudinal and transverse joints should be provided as needed in concrete pavements for expansion/contraction and isolation. Sawed joints should be cut within 24-hours of concrete placement, and should be a minimum of 25% of slab thickness plus 1/4 inch. All joints should be sealed to prevent entry of foreign material and doweled where necessary for load transfer. Load transfer devices, such as dowels or keys are recommended at joints in the paving to reduce possible offsets. Where dowels cannot be used at joints accessible to wheel loads, pavement thickness should be increased by 25 percent at the joints and tapered to regular thickness in 5 feet. Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 40 9.0 REFERENCES 9.1 Site Specific Preliminary Drainage Study, Bonita Glen, Bonita Glen Drive, Chula Vista, California 91910, Latitude 33 Planning & Engineering, Job 1522.00, undated. Bonita Glen Apartments, Studio E Architects, Project 16124, October 17, 2017. 9.2 Design American Concrete Institute, 2002, Building Code Requirements for Structural Concrete, ACI 318-02. American Concrete Institute, 2015, Guide to Concrete Floor and Slab Construction,ACI 302.1R-15. ASCE, Minimum Design Load for Buildings and Other Structures, ASCE 7-10. APWA, 2015 Standard Specifications for Public Works Construction (‘Greenbook’) California Code of Regulations, Title 24, 2016 California Building Standards Code. California Department of Transportation (Caltrans), 2003, Corrosion Guidelines, Version 1.0, available at http://www.dot.ca.gov/hq/esc/ttsb/corrosion/pdf/2012-11-19-Corrosion-Guidelines.pdf. Romanoff, Melvin. Underground Corrosion, NBS Circular 579. Reprinted by NACE, Houston, 1989. USGS, Earthquake Hazards Program, Seismic Design Maps & Tools, accessed 24 November 2017 at: http://earthquake.usgs.gov/hazards/designmaps/ 9.3 Geologic and Site Setting CGS, California Geological Survey, 2009, Tsunami Inundation Map for Emergency Planning, National City Quadrangle,June 1, 2009. Jennings, C. W. and Bryant, W. A., 2010,Fault Activity Map of California, California Geological Survey, Geologic Data Map No. 6. Kennedy, M.P. and Tan, S.S., 2008 Geologic Map of San Diego Quadrangle, Southern California, California Division of Mines and Geology Norris,R.M.andWebb,R.W.,1990,GeologyofCalifornia,SecondEdition: John Wiley& Sons, Inc. United States Federal Emergency Management Agency (FEMA), 2012, Flood Insurance Rate Map (FIRM), Map Number No. 06073C1914G, effective date May 16, 2012. United States Geological Survey and California Geological Survey, 2011, Quaternary Fault and Fold database for the United States, http://earthquake.usgs.gov/regional/qfaults/. California Department of Water Resources, Water Data Library: found at http://www.water.ca.gov/waterdatalibrary/ California Division of Mines and Geology (CDMG), 2008, Guidelines for Evaluating and Mitigating Seismic Hazards in California,Special Publication 117A. . Preliminary Geotechnical Investigation And Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 PLATES                                                                                                                                                                                                                                                                                NO V A NWE NS                                                                                     Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 APPENDIX A USE OF THE GEOTECHNICAL REPORT Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 APPENDIX B SOIL EXPLORATION LOGS  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) 01)4170&9#6'4'0%1706'4'& )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . '     /& &5 '+ #. 5# 48 %0 5'  %4&+'&4+%*647%-#7)'4   NOVA 5#0&;5+.6$4190&4;(+4/64#%'4170&'&)4#8'. $14+0)6'4/+0#6'&#6(601)4170&9#6'4'0%1706'4'&01%#8+0) /. (6 5#0&;5+.6$4190&#/28'4;56+(( )4#;$4190*#4& ;'..19$4190&4;8'4;56+(( Ä /& 5# 5# REH/.  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) 01)4170&9#6'4'0%1706'4'& )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . '     /& &5 '+ #. 5# 48 %0 5'  %4&+'&4+%*647%-#7)'4   NOVA 5#0&;5+.6$4190&4;51(664#%'4170&'&)4#8'. $14+0)6'4/+0#6'&#6(601)4170&9#6'4'0%1706'4'&01%#8+0) /. (6 5#0&;5+.6$4190&4;8'4;56+(( 56+((&#/2 Ä /.  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) 01)4170&9#6'4'0%1706'4'& )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . '     /& &5 '+ #. 5# 48 %0 5'  %4&+'&4+%*647%-#7)'4   NOVA 5#0&;5+.6$4190&4;51(6 $14+0)6'4/+0#6'&#6(601)4170&9#6'4'0%1706'4'&01%#8+0) /. (6 5#0&;5+.6$4190&4;8'4;56+(( 64#%')4#8'. 5+.6;5#0&Ä5#0&;5+.6.+)*6$4190&#/2/'&+7/&'05'1456+((64#%' %1#45'5#0&64#%')4#8'. Ä 5# %4 /'&+7/&'05'148'4;56+(( /'&+7/&'05'1456+(( 5/Ä/. /.  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) 01)4170&9#6'4'0%1706'4'& )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . '     /& &5 '+ #. 5# 48 %0 5'  %4&+'&4+%*647%-#7)'4   NOVA 5#0&;5+.6&#4-$4190&4;51(664#%'4170&'&)4#8'. $14+0)6'4/+0#6'&#6(601)4170&9#6'4'0%1706'4'&01%#8+0) /. (6 5#0&;5+.6$4190&4;61&#/28'4; 56+(( .+)*6$419061)4#;$4190&4;61&#/264#%'%1#45'5#0& Ä 64#%')4#8'. 5# REH 5+.6;5#0&$4190&4;61&#/2/'&+7/&'05' 8'4;56+((015#/2.'4'%18'4; 5/ /.  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) (6 )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . '     /& &5 '+ #. 5# 48 %0 5'  %4&+'&4+%*647%-#7)'4   NOVA  %106+07'&5#0&;5+.6)4#;$4190 /1+56*#4&64#%'4170&'&)4#8'. $14+0)6'4/+0#6'&#6(6)4170&9#6'4'0%1706'4'&#6(601 %#8+0) /. (6 41%-+05#/2.'4 Ä 5/ )4170&9#6'456#$+.+<'& #6(6 )4170&9#6'4(+456 '0%1706'4'&#6(6 5+.6;5#0&.+)*6$41905#674#6'&(+0'61%1#45')4#+0'&5# 5#  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) 01)4170&9#6'4'0%1706'4'& )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . '     /& &5 '+ #. 5# 48 %0 5'  %4&+'&4+%*647%-#7)'4   NOVA 5#0&;5+.6&#4-$4190&4;(+4//. (6 $4190/166.'&&#4-)4#;$41908'4;56+((64#%'%1#45'5#0& &#/256+(( Ä 5#0&;5+.6/'&+7/$4190&#/28'4; 56+((64#%'5#0&.'05'5/+%#%'175 &#4-$4190 REH &#4-$4190 8'4;56+((  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) 01)4170&9#6'4'0%1706'4'& )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . '     /& &5 '+ #. 5# 48 %0 5'  %4&+'&4+%*647%-#7)'4   NOVA 5#0&;5+.6&#4-$4190&4;8'4;56+((64#%')4#8'./. (6 /'&+7/$419056+((01)4#8'. Ä 5+.6;5#0&Ä5#0&;5+.6$4190&#/2 /'&+7/&'05'148'4;56+(((+0'61/'&+7/)4#+0'&64#%'4170&'& )4#8'. &#/2 $14+0)6'4/+0#6'&#6(6&7'614'(75#.01)4170&9#6'4 '0%1706'4'&01%#8+0) 5/Ä/. &'05'14*#4& /'&+7/&'05'1456+(( /& 5# 5#  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) 01)4170&9#6'4'0%1706'4'& )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . '     /& &5 '+ #. 5# 48 %0 5'  %4&+'&4+%*647%-#7)'4   NOVA 5#0&;5+.6&#4-$4190&#/2(+4/64#%'%.#;64#%' )4#8'./. (6 Ä $14+0)6'4/+0#6'&#6(6#0&%108'46'&61#2'4%1.#6+109'.. 5#  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) 01)4170&9#6'4'0%1706'4'& )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . '     /& &5 '+ #. 5# 48 %0 5'  %4&+'&4+%*647%-#7)'4   NOVA 5#0&;5+.6&#4-$4190&#/2(+4/64#%'%.#;64#%' )4#8'./. (6 Ä $14+0)6'4/+0#6'&#6(6#0&%108'46'&61#2'4%1.#6+109'.. 5#  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) 01)4170&9#6'4'0%1706'4'& )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . '     /& &5 '+ #. 5# 48 %0 5'  %4&+'&4+%*647%-#7)'4   NOVA 5#0&;5+.6&#4-$4190&4;51(664#%')4#8'./. (6 Ä $14+0)6'4/+0#6'&#6(6#0&%108'46'&61#2'4%1.#6+109'.. 5# &#/2  %*7.#8+56#%#.+(140+# #22'0&+:$Ä  &' 2 6 * ( 6 241,'%601 .1))'&$; &/ 51 + . % . # 5 5 7 5 % 5 $. 1 9 5 2' 4 Ä + 0 % * ' 5 4'8+'9'&$;$/*9/ &#6' 018 018'/$'4 +0%*&+#/'6'4#7)'4$14+0) 01)4170&9#6'4'0%1706'4'& )4170&9#6'4 $7.-5#/2.' 5265#/2.' #56/& %#./1&5#/2.' #56/& '4410'175$.19%1706 015#/2.'4'%18'4; )'1.1)+%%106#%6 51+.6;2'%*#0)' &+4'%65*'#4 ':2#05+10+0&': #66'4$'4).+/+65 5+'8'#0#.;5+5 4'5+56#0%'8#.7' %1051.+&#6+10 5#0&'37+8#.'06 %14415+8+6; /#:+/7/&'05+6;  )4 # 2 * + % . 1 ) 4'/#4-5$7 . - 5 # / 2 . ' 57//#4;1(57$574(#%'%10&+6+105 75%5%1.14/1+5674'&'05+6;)4#+05+<'16*'4 .# $ 1 4 # 6 1 4 ; %# . 5 2 6 5 # / 2 . 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The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: 7KHLQILOWUDWLRQUDWHRIWKHH[LVWLQJVRLOVIRUORFDWLRQV3WKURXJK3EDVHGRQWKHRQVLWHLQILOWUDWLRQVWXG\ZDVFDOFXODWHGWR EHOHVVWKDQLQFKHVSHUKRXU3 3 3 DQG3 LQFKHVSHUKRXUDIWHUDSSO\LQJDPLQLPXP IDFWRURIVDIHW\)RI) 2 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. Provide basis: 1R6HH&ULWHULRQ ; ; Appendix I: Forms and Checklists BMP Design Manual-Appendices December 2015 I-6 Form I-8 Page 2 of 4 Criteria Screening Question Yes No 3 Can infiltration greater than 0.5 inches per hour be allowed without increasing risk of groundwater contamination (shallow water table, storm water pollutants or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: :DWHUFRQWDPLQDWLRQZDVQRWHYDOXDWHGE\129$6HUYLFHV,QF129$ 4 Can infiltration greater than 0.5 inches per hour be allowed without causing potential water balance issues such as change of seasonality of ephemeral streams or increased discharge of contaminated groundwater to surface waters? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: 7KHSRWHQWLDOIRUZDWHUEDODQFHZDVQRWHYDOXDWHGE\129$6HUYLFH,QF129$ Part 1 Result* If all answers to rows 1 - 4 are “Yes” a full infiltration design is potentially feasible. The feasibility screening category is Full Infiltration If any answer from row 1-4 is “No”, infiltration may be possible to some extent but would not generally be feasible or desirable to achieve a “full infiltration” design. Proceed to Part 2 *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by the City Engineer to substantiate findings 3URFHHGWR 3DUW Appendix I: Forms and Checklists BMP Design Manual-Appendices December 2015 I-7 Form I-8 Page 3 of 4 Part 2 – Partial Infiltration vs. No Infiltration Feasibility Screening Criteria Would infiltration of water in any appreciable amount be physically feasible without any negative consequences that cannot be reasonably mitigated? Criteria Screening Question Yes No 5 Do soil and geologic conditions allow for infiltration in any appreciable rate or volume? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2 and Appendix D. Provide basis: 7KHLQILOWUDWLRQUDWHRIWKHH[LVWLQJVRLOVIRUORFDWLRQ3WKURXJK3EDVHGRQWKHRQVLWHLQILOWUDWLRQVWXG\ZDV FDOFXODWHGWREHOHVVWKDQLQFKHVSHUKRXU3 3 3 DQG3 LQFKHVSHUKRXU DIWHUDSSO\LQJDPLQLPXPIDFWRURIVDIHW\)RI) ,QILOWUDWLRQUDWHVRIOHVVWKDQLQFKHVSHUKRXUDQGJUHDWHU WKDQLQFKHVSHUKRXULPSO\WKDWJHRORJLFFRQGLWLRQVDOORZIRUSDUWLDOLQILOWUDWLRQ,QILOWUDWLRQUDWHVDUHQRW JUHDWHUWKDQ 7KHVHZLGHVSUHDGYHU\ORZWRQRSHUPHDELOLW\VRLODQGJHRORJLFFRQGLWLRQVGRQRWDOORZIRULQILOWUDWLRQLQDQ\ DSSUHFLDEOHUDWHRUYROXPH 6 Can Infiltration in any appreciable quantity be allowed without increasing risk of geotechnical hazards (slope stability, groundwater mounding, utilities, or other factors) that cannot be mitigated to an acceptable level? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2. Provide basis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ppendix I: Forms and Checklists BMP Design Manual-Appendices December 2015 I-8 Form I-8 Page 4 of 4 Criteria Screening Question Yes No 7 Can Infiltration in any appreciable quantity be allowed without posing significant risk for groundwater related concerns (shallow water table, storm water pollutants or other factors)? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: :DWHUFRQWDPLQDWLRQZDVQRWHYDOXDWHGE\129$6HUYLFHV,QF129$ 8 Can infiltration be allowed without violating downstream water rights? The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3. Provide basis: 7KHSRWHQWLDOIRUZDWHUEDODQFHZDVQRWHYDOXDWHGE\129$6HUYLFH,QF129$ Part 2 Result* If all answers from row 5-8 are yes then partial infiltration design is potentially feasible. The feasibility screening category is Partial Infiltration. If any answer from row 5-8 is no, then infiltration of any volume is considered to be infeasible within the drainage area. The feasibility screening category is No Infiltration. *To be completed using gathered site information and best professional judgment considering the definition of MEP in the MS4 Permit. Additional testing and/or studies may be required by the City Engineer to substantiate findings. 1R,QILOWUDWLRQ Preliminary Geotechnical Investigation and Infiltration Study December 4, 2017 Bonita Glen Apartments, Chula Vista, CA NOVA Project 2017826 APPENDIX D LABORATORY ANALYTICAL RESULTS            NOVA x   x     x   x    x    x          NOVA                                                                                   NOVA                      NOVA                      NOVA                      NOVA                      NOVA                      NOVA                      NOVA                      NOVA                      NOVA                      NOVA                      NOVA                      NOVA   