HomeMy WebLinkAboutPreliminary Drainage Study
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 accep tance 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 C hula 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. Access 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
• 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]
• 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.
• “C” factors vary between basins. A weighted “C” value will be used for each basin
based on the ratio of impervious to pervious areas.
• 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).
• Initial travel time values were computed using the Overland Time of Flow
Nomograph (Figure 3-3 in the County Hydrology Manual).
• 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.
• 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.
• 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 fl ow 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 t he 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 biofilt ration basin, the water enters a
proposed catch basin and proposed storm d rain 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 pr oposed
biofiltration basin via curb cut. Once through the biofilt ration 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 existin g
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 biofiltr ation 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 determ ined that during 100-year event
conditions the creek floods overtopping t he 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
100
2.5 5.5 45
-
San Di ego County Hyd ro logy Manua l
Date: Jun e 2003
Table 3-1
Secti o n :
Page :
RUNOFF COEFFICIENTS FOR URBAN AREAS
La nd Use Runoff Coeffic ie nt "C"
Soil T ype
NRC S E leme nt s Count Elements % IMP ER. A B
Undis turbed Na tura l T e rra in (Natura l) Perman ent Open S pace O* 0.2 0 0 .25
Lo w De ns ity Res id enti a l (LOR) Re s identia l, 1.0 D U/A o r less 10 0.2 7 0.3 2
Low De ns ity Res id enti a l (LOR) Resid entia l, 2.0 DU/A or less 20 0.3 4 0.38
Low De ns ity Res id enti a l (LOR) Re s ide ntia l, 2 .9 DU/A o r less 2 5 0.38 0.41
Me dium De ns ity Reside ntial (MOR) Resid e nti a l, 4 .3 DU/A o r less 30 0.41 0.45
Medium De ns ity Reside ntial (MOR) Residentia l, 7.3 D U/A o r less 40 0 .48 0 .51
M edium De ns ity Res ide ntia l (MOR) Res idential, I 0 .9 DU/A or less 4 5 0.52 0 .5 4
Medium Dens ity Re s ide ntial (MOR) Res identia l, 14 .5 DU/ A or less 50 0.55 0.5 8
Hi gh D e ns ity Res id e nti a l (HOR) Residentia l, 24 .0 DU/A or less 65 0.66 0 .6 7
Hi g h De n sity Res identi a l (HOR) Residenti a l, 4 3.0 D U/A or less 80 0 .76 0.77
Comme rci a l/Indus tri a l (N. Com) Ne ig hbo rh ood Commerc ia l 80 0.76 0.77
Comme rc ial/Indus trial (G. Com ) Ge ner a l Comm e rc ia l 85 0.80 0 .8 0
Comme rc ia l/Indus tri a l (O.P. Com) Offi ce Pro fess io na l/Commerc ia l 9 0 0.83 0 .84
Comme rcial/In d us tri a l (Limited I.) Limite d Industri a l 90 0.83 0 .84
Commercial/Indus tri a l (Gene ral I.) Ge neral Indus tri a l 95 0.87 0 .87
c
0 .3 0
0 .36
0 .42
0 .45
0.48
0 .54
0 .5 7
0 .60
0.6 9
0.78
0.78
0.8 1
0 .8 4
0.84
0.87
3
6 of26
D
0 .35
0 .4 1
0.46
0.4 9
0 .52
0 .57
0 .60
0 .63
0.71
0.79
0 .7 9
0.82
0 .85
0 .85
0 .87
*Th e valu es assoc iated wi th 0 % imperv ious m ay be used fo r direc t c a lcu lati o n o f th e run off coeffi c ie nt as d escribe d in Secti o n 3.1 .2 (r epresentin g th e pervi o us runoff
c oe ffi c ie nt, C p, fo r th e soil ty pe), o r fo r areas th at will re main undi s turbed in perpetuity. Justifi cat ion mus t be g iven th a t the ar ea w ill remain na tura l fo rever (e.g., th e a rea
is locate d in C levela nd Nati o na l Forest).
DU /A = dwe lling units per acre
NRCS =N ati o na l Reso urce s Conservati o n Servi ce
3-6
TECHNICAL MEMORANDUM:
Hydrologic & Hydraulic Analysis for
Bonita Glen Creek
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:
( ) ( )
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:
( )
( )
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:
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.
Bonita Glen Creek
January 25, 2018
APPENDIX 1 – RATIONAL METHOD ANALYSIS
1/24/2018 Pr ecipitation Frequency Data Server
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.htm l?lat=32.6428&lon=117.0612&data=depth&units=english&series=pds 1/4
NOAA Atl as 14, Volume 6, Version 2
Location name: Chula Vista, California, USA*
Latitude: 32.6428°, Longitude: 117.0612°
Elevation: 170.95 ft**
* so urce : ESRI Maps
** sou rce: USGS
POI NT PRECIPI TATION FREQUENCY E STI MATE S
San ja Perica, Sarah Die tz, Sara h Heim, Lillian Hiner, Ka zun gu Maita ria, Deb ora h Ma rtin , Sa ndra
Pavlo vic, Isha ni Roy, Carl Tryp aluk, Da le Unru h, Fenglin Yan, Mich ael Yekta, Tan Zha o, Geoffrey
Bonn in, Dan iel Brewer, L iCh uan Che n, Tye Parzybo k, Jo hn Yarchoa n
NOAA, Natio nal Weathe r Se rvice, Silver Spring, Marylan d
PF_tabular | PF_graphic al | Maps_&_aerials
PF tabular
PDSbased 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
5min 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)
10m in 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)
15m in 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)
30m in 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)
60m in 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)
2hr 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)
3hr 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)
6hr 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)
12hr 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)
24hr 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)
2day 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)
3day 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)
4day 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)
7day 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)
10day 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)
20day 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)
30day 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)
45day 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)
60day 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 Pr ecipitation Frequency Data Server
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.htm l?lat=32.6428&lon=117.0612&data=depth&units=english&series=pds 2/4
1 Precipitation frequenc y (PF) estimates in this table are based on frequency analysis of partial duration s eries (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% c onfidence interval. The probability that precipitation frequenc y es timates (for a
given duration and average rec urrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
c hec ked agains t probable maximum precipitation (PMP) es timates and may be higher than c urrently valid PMP v alues.
Pleas e refer to NOAA Atlas 14 doc ument for more information.
Back to Top
PF graphical
cur ve plots
Back to Top
Maps & aerials
S mal l scal e terrain
+
–
3km
2mi
1/24/2018 Pr ecipitation Frequency Data Server
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.htm l?lat=32.6428&lon=117.0612&data=depth&units=english&series=pds 3/4
Large scal e terrain
Large scale map
Large scal e aeri al
Back to Top
E rror 500: I nternal Server E rror. P lease t ry anot her location.
+
–
100km
60mi
+
–
100km
60mi
+
–
100km
60mi
NOAA Values Interpretation
2‐Year 10‐Year 100‐Year
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)
Bonita Glen Creek
January 25, 2018
APPENDIX 2 – HYDRAULIC ANALYSIS
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
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
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