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HomeMy WebLinkAboutRCC AGENDA PK 1994/01/10Mitigated Negative Declarati PROJECT NAME: PROJECT LOCATION: ASSESSOR'S PARCEL NO.: PROJECT APPLICANT: CASE NO: IS-91-15 A. Project Settine DATE: July 28, 1993 The proposed project consists of the annexation and prezoning of 8.52 acres currently located in the County of San Diego to the City of Chula Vista and subdivision of the site into residentia] lots. The site consists primarily of a rectangular tract of land abutting the Bonita Valley Reservoir on the west, north of the terminus of Moonview Drive. Although the site was farmed many yeazs ago, a variety of vegetation is on the site. The southern end of the property features anorth-facing slopes with disturbed vegetation which gradually drops into a drainage with sage scrub. The terrain rises again to the north onto a bazren ridgeline, before dropping steeply into Bonita Valley. On the eastern boundary near the center of the site is a disturbed fill slope abutting a buried reservoir. The 18.7 million gallon reinforced concrete Bonita Valley Reservoir to the east includes a two foot earthen "blanket" over the concrete, on which sage scrub was seeded. The high elevation is 308 feet at the south end of the property, on a hillside below the existing water tank while the low elevation is approximately 116 feet in the extreme northwestern corner of the property on a steep slope overlooking Bonita Valley. B. Proiect Description The proposed project is~ an annexation to the City of Chula Vista and prezoning of approximately eight acres and subdivision of the site into thirteen lots. Twelve of the lots will be for development of custom homes, two of the lots will be dedicated open space for protection of sensitive environmental resources. Site access will be via Moonview Drive which will be gated at the entrance to the site. The site is bounded by existing single family residences at the northeastern and southwestern corners, water storage facilities at the eastern and southern portions, a partially improved road at the northwest boundaries, Moon View Drive at the southeastern corner, and undeveloped land at the remaining boundaries. The property to the north, east and west is in the County of San Diego and designated Residential-Low (0-3 du/ac), Residential 1 and Residential 5, respectively, on the Sweetwater Community Plan. The property to the south (Terra Nova) is in the City of Chula Vista and is designated Residential-Low Medium (3-6 du/ac) on the City's General Plan. Zoning for Bonita Hills Executive Estates North of the Terminus of Moonview Drive APN: 592-030-58 Michael Anthony Demich city of Chula vista planning department environmental review section ~~tr, ~~ CITY OF CHUTA VISTA the property to the north, east and west is RR-I (to the north and east) and RS-4 (to east and west). Terra Nova is zoned PC (Planned Community) by the City of Chula Vista. C. Comnatibiliri with Zoning and Plans The project site's General Plan designation in the County of San Diego is Residential-Low (0-3 du/ac). The proposed City of Chula Vista General Plan designation for the site is Residential-Low (0-3 du/ac). The current zoning, under [he County of San Diego is RR-1 (1 acre minunum lot size). The proposed City of Chula Vista zoning is RE-P (minnnum lot size of 20,000 squaze feet). D. Identification of Environmental Effects An initial study conducted by the City of Chula Vista (including the attached Environmental Checklist Form) determined that the proposed project could have one or more significant envirotmental effects. Subsequent revisions in the project design and/or specific mitigation measures will be implemented to reduce these effects to a level below significant. With project revisions and/or mitigation, no significant environmental effects will occur, and the preparation of an Environmental Impact Report will not be required. This Mitigated Negative Declaration has been prepared in accordance with Section 15070 of the State CEQA Guidelines. Specific mitigation measures are set forth in the Mitigation Monitoring Program which is attached as Attachment "A". The following impacts are those that were determined to be potentially significant and are required to be mitigated to a level below significant. A discussion of each of these potentially significant but mitigatable impacts from the proposed project follows. BIOLOGICAL RESOURCES Existing Conditions: A biological survey was performed on the 8.52-acre Bonita Hills Executive Estate site to identify sensitive biological resources and constraints for future development of the site. The Biological Assessment for the site is on file in the City of Chula Vista Planning Department. The survey revealed that the site is utilized by both Coastal Cactus Wrens and the California Gnatcatcher. The former inhabits sage scrub and cactus neaz the ravine along the western fenceline, and territories extend off-site into higher quality habitat immediately west. The gnatcatchers were noted at the same locale; as well as in sage scrub now growing on the eastern boundary of the site and further into the earthen seal for the reservoir (off-site). Two easements of 1.21 and 1.50 acres, which represent approximately 30% of the project site, are proposed as dedicated biological open space to protect these sensitive birds and their habitat. Two plants of limited sensitivity were noted: several California Adolphia grow near the ravine along the western boundary, and eight San Diego Viguiera occur further upslope to the north. Habitat quality varies widely on the property, with disturbed grasslands in the south and north, and fair to good quality Diegan Sage Scrub covering much of the canyon's flanks in the center of the property. Two vegetation types were present on the property: Diegan Sage Scrub and a very disturbed Annual Grassland. Shrub diversity at the Bonita Hills site is relatively limited. The more diverse sage scrub C:\N AN CY\\DEMICH.IS\ is concentrated near the drainage along the western boundary. Unusual for the region is the high incidence of California Encelia, which although a common plant, is rarely the dominant cover. Also occurring is Coastal Sagebrush, Lemonadeberry in the more mesic canyon bottom, Flat-top Buckwheat, Spanish Bayonet and Black Sage. Near the western boundary, by the drainage, grows some Jojoba, Coast Cholla, and further upslope San Diego Viguiera in limited numbers. The understory is relatively limited. Native elements include the late-flowering San Diego Want Chicory, Bicolored Cudweed, Ocean Locoweed and California Filago. At one aztificially moist locale, along the southern boundazy, near an irrigated residential yazd, is one Arroyo Willow and a Great Marsh Evening Primrose. No other wetland species were seen on the property. The disturbed Annual Grassland/Disturbed habitat includes an abundance of the noxious Tecolote and Wild Mustard. The overall quality of this grassland is considered poor. Much of the grassland habitat in the south may have been created during construction of the adjacent buried reservoir. Grassy areas on the ridgeline in the north are likely the result of peripheral residential disturbance. Of the species of plants that were recorded on the site, thirty-seven are non-native invasive elements. None of these additional species is expected to be listed as sensitive. The Diegan Sage Scrub and Annual Grassland aze habitat types for wildlife on the site. A small canyon with a few large shrubs at the western end of the property is kept moist by suburban runoff. This is an attractive area for animal-life in an otherwise arid environment. Two sensitive species of birds were observed utilizing the available sage scrub habitat, Coast Cactus Wren and California Gnatcatcher. No amphibian were observed. Only one species of reptile were observed. Fifteen species of birds were observed on the site. Most of the species were associated with the natural sage scrub habitat. As many as six Coastal Cactus Wrens were observed. One pair of California Gnatcatchers utilize this property. No nesting activity was detected, but the quality of the available sage scrub habitat is rather good. A separate single gnatcatcher was seen and heard briefly to the northeast of this property along Randy Lane, indicating their presence there as well. Another pair of gnatcatchers uses the revegetated sage scrub covering the adjacent underground reservoir and the small tract of sage scrub off-site in the southeast (south of Moonview Drive). Desert Cottontail was observed. Coyote was detected from its scat. California Ground Squirrel burrows were found, and they undoubtedly occur on-site, particularly within the disturbed terrain. Potential Environmental Impacts: Both the Riversidian phase and the Diegan phase of Coastal Sage Scrub have been severely reduced in total acreage over the last century. Along with the extensive reduction in sage scrub has come a piecemeal fragmentation of lazger tracts of such habitat. Isolation into small parcels devoid of viable linkages to other similar lands has undercut the value of such lands. Substantial redesign has eliminated initial significant biological impacts. Several adverse biological impacts will result from the proposed 12-lot split. _ • Loss of 1.5 acres of Diegan Sage Scrub. This habitat is severely declining in the Bonita region due to urban development and its conservation is a focus of regional C:\NANCY\\DEMICH.IS\ Page s planning for both Chula Vista and San Diego County. This highest quality sage scrub is situated in proposed open space B. Impacted sage scrub is of lesser or degraded quality. • The loss of eight San Diego Viguiera are not considered biologically significant. CULTURAL RESOURCES Existing Conditions: An Archaeological/Historical Assessment was prepared for the project site to determine if any significant cultural resources were present. The entire Cultural Resource Survey is on file in the City of Chula Vista Planning Department. Record seazches were conducted at the San Diego Museum of Man and the South Coastal Information Center at San Diego State University to identify previously recorded archaeological sites within one mile of the site. No sites were recorded on the project site, however, the record searches indicated that ten prehistoric sites have been recorded within one mile of the property. All sites are located along ridge tops overlooking either side drainages or the Sweetwater River. In 1981, the project site was part of a larger survey for Sweetwater Authority for the Bonita Valley Reservoir Site. As a result of the 1981 investigation, no cultural resources were recorded. The 1981 study concluded that the area had been a working farm for over thirty years. Historic maps and aerial photographs do not reveal any pre-1942 farmsteads or activities on the site, although they do reveal the farm activities mentioned in the 1981 report, occurring on the knoll top by 1944. Although, according to the 1981 study, debris related to farming was found on the site, none of it was determined to be significant. No mitigation was required at that time. The entire site was again surveyed for the current study in September, 1992. No prehistoric or historic resources were located. Sprinkler heads were noted through the property suggesting the possibility of past farming activities. Miscellaneous trash, asphalt and cement chunks and pieces of road gravel were noted primarily along the road. A small, abandoned area, likely the remnants of a worker's camp containing trash and a wooden platform, was located in the southwest area. It was determined to be non-significant, and therefore, no mitigation is necessary. SOILS Existing Conditions: A Soil and Geologic Reconnaissance was to prepazed by Geocon,Inc. to provide preliminazy geotechnical information relative to the development of the proposed subdivision. The Geocon, Inc. study is on file in the City of Chula Vista Planning Department. Two geologic formations and two surficial deposits were encountered during the reconnaissance. The geologic formations consisted of Oligocene-aged Otay Formation and Pliocene-aged San Diego Foundation. The surficial deposits consisted of fill and topsoil. The Oligocene-aged Otay Formation is located near the northern portion of the site. The Otay Formation does have contact with the younger (overlying) San Diego Formation within the open space azea of Open Space L.ot "A". The formation generally consists of dense sandstone and claystones. Due to the formation being located only within the open space area it should not be encountered during grading for the proposed development. C:\NANCY\\DEMICH.IS\ The San Diego Formation (Tsd) is a dense, tan light gray, silty, fine-grained (with some gravel) associated with the San Diego Formation which appears to be the predominant formation underlying the site. Excavation within this unit will likely require moderate to heavy efforts with conventional heavy-duty grading equipment. Localized cemented zones, if encountered, may require a very heavy effort. The San Diego Formation should provide suitable foundation engineering characteristics for proposed structures in either an undisturbed or properly compacted condition. Cut slopes and compacted fill slopes constructed at 2:1 (horizontal: vertical) or flatter should generally be stable. These soils, when used to construct fill slopes, are very susceptible to surficial erosion and should be properly planted to reduce the potential for erosion. Topsoils consisting of silty to slightly clayey, fine sands were observed overlying the formational units and were visually classified as relatively "low" -expansive with observed thicknesses of approximately 1 to 2 feet (where exposed) and may be as thick as 3 feet in some locations. Due to the generally loose, unconsolidated nature of the topsoil, it should be removed and recompacted prior to placing fill or structural loads. There is a fill slope, on the site, associated with the underground reservoir east of the project site. Where fills are proposed above the existing reservoir fill soils, these areas may require subsurface investigation (trenches, etc) where structural improvements are considered. Other minor fills were noted on, or adjacent to, the site. These soils will require additional investigation where improvements are proposed. It is anticipated that the above-mentioned fills were derived from soils similar to those previously discussed. No evidence of landslides was found in previous reports or photographs and none were observed on the site. No groundwater or seeps were observed during the recormaissance. The site is no[ located on any known active or potentially active fault trace. The Coronado Banks Fault, which is considered to be active, lies approximately 18 miles west of the site. The Rose Canyon Fault is located approximately 8 miles from the site and is the closest active fault to the site. The site is located within the La Nacion Fault zone with the nearest splay approximately 1,600 feet to the west. Regional active faults include the Elsinore Fault and the San Jacinto Fault zones, which lie approximately 41 and 62 miles to the northeast, respectively. In an event of a major earthquake on these or other faults in the southern California region, the site could be subjected to moderate to severe ground shaking. With respect to this hazard, this site is comparable to others in the general vicinity. Due to the high density of prevailing formational soils at the site, anticipated remedial grading of the surficial soils, and the lack of a permanent near-surface groundwater table, there does not appear to be a significant risk of seismically induced liquefaction occurring on the property. Miti¢ation Measures: Conclusion• No significant soil or geologic conditions have been observed or aze known to exist which would preclude development of the property. Provided the mitigation recommendations in the Geologic Reconnaissance are adhered to there will be no significant impact related to geology or soils. C:\NANCY\\DEMICHIS\ Page 5 DRAINAGE/HYDROLOGY Existine Conditions: Due to the topography of the site, drainage is considered to be a potentially significant impact. A Drainage Study was prepared for the site and is on file in the City of Chula Vista Planning Department. The subject property is dominated by a saddle located in the center portion of the property between two knolls located on the northern and southern extremes of the project. The proposed northern six lots would be developed on the descending ridgeline of the northern knoll. The southern six lots would be located on the northern side of the southern knoll. The central saddle descends to a canyon and natural drainage course to the west. The northern 150 feet of the property is steep in grade and would not be disturbed by the proposed project. Due to the site's location in close proximity to hilltops, very little offsite land (approximately 1.1 acres) contribute to the study azea's drainage basins. In a natural condition, only property to the east would naturally drain towards the project. However, the drainage generated offsite to the east of the site is collected in the Sweetwater Authority storm drain system and directed to the northeast away from site The drainage study area consists of two well-defined drainage areas. The area to the north of the ridgeline of the northern knoll encompasses approximately 2.1 acres and generates 4.27 cubic feet/second (cfs) of run-off in a 100-year storm. This water exits the project site in an even sheetflow down the steep slope descending to the north of the site. The second existing drainage area encompasses the majority of the project site which is located south of the ridgeline of the northern knoll, along with a small area off-site on the slope of the southern knoll and portions of the canyon banks to the west. This basin generates an existing 18.14 cubic feet/second (cfs) of run-off in a 100 year storm which is concentrated offsite into the flowline of the small canyon descending westerly from the central project site area. A portion of the access road abutting the central portion of the site along its eastern boundary is part of the proposed subdivision, however, it has not been included in the Drainage Study since the road is already developed and its drainage is collected in the storm drainage system developed as pazt of the underground reservoir and discharged offsite. No change in this drainage is proposed as pazt of the proposed project. Proposed Developed Drainaee: The developed drainage analysis is based on proposed site improvements as shown on the tentative map for the project Chula Vista Tract Map No. 91-2 dated March 3, 1993. The drainage basin areas following site development will remain basically the same as in the existing condition (see Figure 1). There would be little change in Drainage Area B. For the three lots proposed on the north side of proposed Street "C", the reazyazds would sheet drain to the north and the frontyards would drain south to the street. Though there will be a small increase in Drainage Area B, it will be offset by the increased time of concentration due to the shallow slope of the proposed pad. Therefore, although there will be a slight increase in drainage, it does not constitute a significant impact. C: \N AN CY\\DEMICH.IS\ 1 I y/ I C m~ _ _._ ,._ _ ... " ao.._ _..~' E r :e.ki ,°°a a ~;°-p£a ki ,..> m m '";r - i _ ._-. .. ___ £ ` f°3 ~ BEai § R eYEfR §~ a~ 4e y - .' i ~ o ~ Epg ~~~s ~ k :g.3~ §` 1 Z3S ~ I" m i sl~'%' ~ ~~~ ._ ~~: r ~~ k ° ~e,E pE§i n i:gg .:~ ~ogi(:ppdd iT a~'~ ~ :~-. ~ /~ n, a•; f k Fay. 'r s, ci s" a e FF .ag6 ~.~~ ~ ~ ~ g x, F.. r `. ~ ,. c ~ p E I.~ ^~ \ y F .. r .\ ,, ~ ~. tl _ ... e 5F o J~ ~ i. F ~ ©f~ .•/ . Cnp ,, s ,,. ~~.,,/~ r, z. ~~ sip ;T r~ ._ I/~ I- .. C. V // ~ \ ~ \ ~: ~ 1 If toy .I y' I, s~~ ~P~ _ w~- '- - \ ' r 1 t°R ~ ~ G ~ ~ -I j T ~y ~1 r ~ i a., .. ~. ~~\ IA I `~° ~ IAA"~IIII .d~ 1 R7 II i 7~ VIII 3£ 5 O ~ z ' ='„nln /V I ~' 9 1 I r5B~9 ~ D "y ,C, '•1 AI~'m o,-~ ~ I s ~~~ ~' i'' I ~~ gEP ~ ~` I 2 (~ = ' I E' 9 - ~p~p^~~?711y15Ri ~i.".n ~ o ~!il i4 ~;~~ ~'F°'~ ~~ r~z ~6( rkf I~ Yjf ~' J.- r~?I 1 ~°a=~ '~ fn -I ~{ .I: ~~~~ '.~~~ ~,/~I dill 'QI',',I es~~; j ~, ~~ , ~ ~ I 1 1 ^I IIxR ' m Q V . , f c~ :. ~ ae~ 1 I I ,L -i j...._i- ' 4 h ,,.E , a' ~. -~ fpb/ r _ - r ~"' ~ \ . Vin. ~ _ ...i. - - _~ i \ ~ O C/~ i ,' i \ /COQ/~, '~~" CP nTy~ -- \;.~\~\ ~. - 1 ~0 ,• 1 ~ DT I~/ ir~• .. a~ F~ 1 V _ E ~~/ e \ \\~P~ it ~• I'G 'f ~ 1~ I ~:; ~ ~ _ o.. a..~ L ~x P[~ IIL _ '' bl - IT , 1 ~~~~ 4n R OMr W7 T \r (~, N W W T ~ +~3 a 41 ~~ X 1 1 ~ 1 V I ~, e[,, , ~ ~ 111 ~ 'EY~S~ ~ I LO7 A - ~a Lpa 7 '~[+- F CF•IUL Vla-f,1 "f fl ACf ;JO-~~ -' aTlt ~~~ i, E _.;~ €g ~ 2 . .. e SS_ 9 I ., Z 11.d'--._. __._._-- .. .. n~3i ~ Q ° .'.1-:~.~_n__~~..i _. i~ g~ :~ ~ ~... 'il.~'e, n Drainage Area A will be impacted due to the construction of a surface collection and underground drainage conveyance system for the proposed development. Some run-off from portions of Area A will be conveyed in a different manner than in the existing condition. Drainage Subareas A,, AZ, A3, A4 and A5, will be directed to the underground storm drain system with its outlet in Lot B. Drainage Subareas A6 and A~ will be collected at the rear of the graded pads, duetted to the rip rap energy dissipators to be located on the north side of these lots, from which they will drain into the western canyon. The Drainage Study concludes that there will be a slightly lower quantity of runoff after development than in the existing condition, due to the drainage improvements that are proposed. This reduction is due to the lazger time of concentration caused by the change in landform and increased time for the drainage to be routed in the street curb and gutter system prior to release in the underground storm drains. Erosion/Sedimentation: There is minimal erosion currently from the site due to dense vegetation on the canyon slopes and the sheetflow nature of the existing drainage pattern. In the developed condition, all of the drainage subareas of Area A except for AS will be concentrated, and thus increasing its erosive possibilities. Drainage Subareas A, through A, and A6 and A, have a total quantity of approximately 9.05 cfs. If this quantity were released directly in a concentrated condition on the canyon sideslopes, the slopes could erode and cause downstream siltation. This can be eliminated by extending the storm drains to the flowline of the existing canyon and reducing the outlet velocities. The extension of the storm drains to the flowline along with the proposed installation of rip rap and splashwalls would mitigate the impact of the increased drainage from the proposed development. WATER QUALITY/EROSION: Due to the topography of the site, sedimentation could be a significant short- and long-term impact. The long-term impact related to drainage has been addressed in the drainage section above with appropriate mitigation measures recommended. Erosion and sedimentation impacts during the grading and construction period would be short-term, especially after storm events, and would be potentially significant. These impacts would occur only if adequate erosion control measures are not applied during and after the earthwork stage when disturbed soil is left temporarily unprotected. Long term erosion may occur from exposure of graded land if the area is not adequately landscaped soon after grading. These impacts are also considered to be potentially significant. The applicant will be required to comply with the General National Pollutant Discharge Elimination System (NPDES) permit issued to San Diego County by the State Water Resources Control Board for grading and construction activities. Individual projects fall under the General Permit issued to San Diego County by filing a Notice of Intent (NOI), including a Storm Water Pollution Prevention Plan (SWPPP), with the State Water Resources Control Board prior to commencing grading activities. The SWPPP also addresses runoff from the site after construction to ensure that the future runoff is in compliance with the NPDES. Implementation of the recommended mitigation measures will mitigate the impact of sedimentation to less than significant. C:\NANCY\\DEMICH.IS\ Page 8 E. Mitigation necessary to avoid significant effects Specific project mitigation measures are required to reduce potentially significant environmental impacts identified in the initial study for this project to a level below significant. Mitigation measures have been incorporated into the project desigri and have been made conditions of project approval, as well as requirements of the attached Mitigation Monitoring Program (Attachment "A"). BIOLOGICAL RESOURCES Two dedicated open spaces are recommended, and have been incorporated into the tentative map, which will include 1.2 acres of the higher quality Diegan Sage Scrub on-site in Area A, and protect habitat for both the Coastal Cactus Wren and the California Gnatcatcher. The California Adolphia will also be protected within these aeeas. The western open space (Area B) is 1.5 acres and is contiguous with high quality cactus wren and gnatcatcher habitat off- site to the west. It also links the revegetated lands of the reservoir with this sage scrub- dominated habitat (separated only by the existing paved road). Lot A covers a steep north- facing slope with grassland habitat. Specific mitigation measures to avoid specific significant biological impacts are as follows: 1. No clearance of vegetation or other forms of habitat and soil disturbance shall occur within the dedicated open space areas (Lots A and B), with the exception of the construction of the sewage pipes and storm drainage pipe. In such case, disturbance shall be at the minimum required to accommodate construction. 2. 0.3 acre of disturbed grassland Diegan Sage Scrub in Lot B shall be revegetated in accordance with the recommendations in the Pacific Southwest Biological Services Assessment for the project dated September 4, 1992. Artemisia californica, Encelia californica, Eriogonum fasciculatum, Diplacus puniceus, and Salvia mellifera should be the principal shrubby components of this revegetation. A three-year monitoring plan shall be implemented to ensure the successful establishment of this scrub. The 0.3 acre constitutes the entire area within Area B mapped as grassland. 3. Prior to consideration of any final subdivision or parcel map, issuance of a grading permit, or issuance of a building permit for any portion of the project site, proof of an incidental take permit under Section 7, Section l0a of the Endangered Species Act or any other form of approval by the US Fish & Wildlife Service, relative to the California Gnatcatcher or Coastal Sage Scrub, shall be provided to the Envirottmental Review Section of the Planning Department. If such permit is not required, written verification to that effect from the U.S. Fish and Wildlife Service shall be provided. Any project redesign required in obtaining a Section 7 or l0a permit may require reconsideration by the appropriate City decisionmaking body. CULTIJRAI. RESOURCES No significant impacts were identified, therefore, no mitigation is necessary. C: \N ANCY\\DEMICH.IS\ SOILS 4. All recommendations of the Soil and Geologic Reconnaissance prepared for the Bonita Hills Executive Estates by Geocon Incorporated, dated December, 1992, shall be adhered to. 5. A 20- to 30-foot high near vertical slope within the central drainage at the western boundary may experience additional erosion. Consideration should be given in the design process for future slope relation within the immediate azea. 6. All future geotechnical subsurface investigation for the site should include review of the fill compaction report for the underground water reservoir at the eastern boundary. 7. The topsoils overlying the formational units will require remedial grading in the form of removal and recompaction in areas of proposed improvement. A subsurface investigation and laboratory testing will be required to determine actual depths of removals. 8. Existing fills in areas of proposed improvement should be evaluated during future investigations. 9. Excavations within the on-site soils should generally be possible with moderate to heavy efforts with conventional heavy-duty grading equipment. Localized cemented zone, if encountered, may require a very heavy effort. 10. Deleterious materials encountered during grading, such as tree roots, should be excavated and disposed of off site. 11. Cut and fill slopes planned at inclinations of 2:1 (horizontal:vertical) or flatter with maximum heights of 13 feet should generally be stable against deep-seated failure. 12. Cut and fill slopes will be provided with an erosion-resistant ground cover and an adequately designed and maintained irrigation system as soon as practical to reduce the erosion potential. Constructed slopes should be designed with appropriate drainage systems; water will not be allowed to discharge over the top of slopes. 13. In general, the prevailing soil conditions in either a dense undisturbed or properly compacted condition aze suitable for the support of conventional isolated and continuous spread footings. It is anticipated that "very low" expansive soils will be encountered or will be placed as fill in the aeeas influencing future foundations. Foundation design, including an allowable soil bearing pressure and estimated settlements, should be incorporated within future geotechncial studies. 14. Prior to the finalization of the grading and improvement plans, a detailed soil and geologic investigation addressing the proposed development shall be performed. C:\NANCY\\DEMICH.IS\ Page 10 DRAINAGE/IIYDROLOGY 15. All drainage improvements shown on Tentative Map 91-2 dated March 2, 1993, including rip rap velocity dissipators at outlet locations on the banks of the existing slopes, shall be implemented to the satisfaction of the City Engineer. 16. Storm drains shall be extended to the flow line of the canyon. Outlets and energy dissipators shall be designed to the satisfaction of the City Engineer. WATER OUALITYi'EROSION: 17. The developer shall prepare an erosion and sedimentation control plan, in compliance with the NPDES permit issued to San Diego County, for the proposed development to address the impacts of short-term construction and grading activity. Said plan shall be incorporated into the project's grading and construction plans and shall be approved by the City Engineer prior to issuance of grading permits. 18. The project shall comply with the provisions of the State Water Resources Control Board (State Water Board) Order Number 92-OS-DWQ, National Pollutant Discharge Elimination System (NPDES) General Permit Number CAS 000002, Waste Discharge Requirements (WDRS) for Discharges of Storm Water Runoff Associated with Construction Activity including the preparation of a Storm Wa[er Pollution Prevention Plan. 19. All graded slopes shall be properly planted to reduce the potential for erosion. Landscape plans shall be subject to approval of the Planning Director prior to issuance of grading permits. C:\NANCY\\DEMICH.IS\ Page 11 F. Consultation 1. Individuals and Organizations City of Chula Vista: Marilyn R. F. Ponseggi, Planning Consultant Roger Daoust, Engineering Cliff Swanson, Engineering Hal Rosenberg, Engineering Bob Sennett, Planning Ken Larsen, Director of Building & Housing Carol Gove, Fire Marsha] Crime Prevention, MaryJane Diosdada Marty Schmidt, Pazks & Recreation Dept. Rich Rudolf, Assistant City Attorney Chula Vista City School District: Kate ShurSon Sweetwater Union High School District: Tom Silva Applicant's Agent: Sidney Xinos, Xinos Engineering David B. Parot, Xinos Engineering 2. Documents Chula Vista General Plan (1989) and EIR (1989) Title 19, Chula Vista Municipal Code Biological Assessment of the Proposed Bonita Hills Estates, City of Chula Vista , California, prepared by Pacific Southwest Biological Services, Inc., September 4, 1992, revised March 16, 1993 (Appendix "A") Cultural Resources Survey of the Proposed 8.9 acre Demich Subdivision Chula V~ Tract X191-2, Chula Vista, California, prepared by Roth and Associates, September, 1992 (Appendix "B") Soil and Geologic Reconnaissance for Bonita Hills Executive Estates, Chula Vista, California, prepared by Geocon, Inc., December, 1992 (Appendix "C") Drainage Study for Bonita Hills Executive Estates, prepared by Xinos Enterprises, Inc., Mazch 31, 1993 (Appendix "D") C: \NANCY\\DEMICH.IS\ Initial Study This environmental determination is based on the attached Initial Study as well as any comments on the Initial Study and this Mitigated Negative Declaration, and reflects the independent judgement of the City of Chula Vista. Further information regarding the environmental review of the project is available from the Chula Vista Planning Department, 276 Fourth Avenue, Chula Vista, CA 91910. /~ ENVIRONMENTAL REVIEW'COORDINATOR EN 6 (Rev. 5/93) C:\NANCY\\DEMICH.IS\ Y3gC IS