ATTACHMENT D
ENVIRONMENTAL IMPACT REPORT
APPENDIX K
HYDROLOGY STUDY
PRIORITY PROJECT
HYDROLOGY STUDY
FOR:
CAPALINA APARTMENTS
APN No. 219-115-33
Capalina Road, San Marcos, CA 92069
PREPARED FOR:
Capalina SMA, LLC
179 Calle Magdalena #201
Encinitas, CA 92024
Attn: Jon Rilling
Tel No.: 760-445-5144
PREPARED BY:
EXCEL ENGINEERING
440 State Place
Escondido, CA 92029
Tel: (760) 745-8118
Project No: 22-060
DATE PREPARED:
6/12/2023
TABLE OF CONTENTS
1.0 Project Description
1.1 Project Purpose
1.2 Project Proposed facilities
2.0 Vicinity Map
3.0 Site Map
4.0 Description of Watershed
4.1 Existing Conditions Topography and Drainage Patterns
4.2 Post Conditions Topography and Drainage Patterns
4.3 Hydrologic Unit Contribution
5.0 Methodology
5.1 Hydrology Software
5.2 Routing Software
5.3 Soils Type Determination
5.4 Isopluvial Value Determination
6.0 Calculations
6.1 Calculate Runoff Coefficient
6.2 Manning Roughness Coefficient
6.3 Rational Method Calculation Summary
7.0 Summary
8.0 References
9.0 Declaration of Responsible Charge
10.0 Attachments
Attachment 1 – Site Map
Attachment 2 – Figures & Tables from the SD Hydrology Manual 2003
Attachment 3 – Watershed Information
Watershed Map
Soils Index Map
Soil Report
Rainfall Isopluvial Maps
Attachment 4 – Pre-Development Condition Exhibit
Attachment 5 – Post-Development Condition Exhibit
5a. Hydrology Map of Post-Development Condition Exhibit 5b. Hydrology Map of Post-Development Mitigation Condition Exhibit
Attachment 6 – Modified Rational Method Runoff Calculations
6a. CivilD Pre-Development Calculations
6b. CivilD Post-Development Calculations
6c. CivilD Mitigated Post-Development Calculations
Attachment 7 – Hydrograph
7a. HEC-HMS Simulation Results
7b. Runoff Coefficient C After Detention Structure
1.0 Project Description
1.1 Project Purpose
The objective of this study is to determine the flow rates from 100-year runoff analysis for the existing site conditions and compare that analysis to the 100-year runoff generated from the proposed project. We will also calculate the adequacy of the proposed storm drain facilities and mitigation measures to maintain existing peak flows.
1.2 Project Proposed Facilities
The 2.51-acre project site is located on Capalina Road in the City of San Marcos, California. The site is currently undeveloped. The project site fronts on West Mission Road to the north and Capalina Road to the south, existing commercial development is adjacent to the sites westerly and easterly boundaries.
The proposed project is a multifamily residential facility containing two buildings and associated surface parking and supporting utilities. The proposed drainage facilities include two biofiltration basins, an underground storge tank used to mitigate the projects peak flow and associated storm drain systems which outlet to Mission Road.
2.0 Vicinity Map
The project site is located on Capalina Road in the City of San Marcos, California. The project site fronts on West Mission Road to the north and Capalina Road to the south.
Fig. 1 Vicinity Map
3.0 Site Map
Please see Attachment 1 – Site Map
4.0 Description of Watershed
4.1 Existing Conditions Topography and Drainage Patterns
The existing site is currently undeveloped. The project fronts on West Mission Road to the north and Capalina Road to the south. The property drains primarily by overland flow to West Mission Road then easterly along West Mission Roads curb and getter to an existing storm drain system located at North Pacific Street.
According to the Web Soil Survey, the soil types for this site are Type C and Type D.
Table 3-1 Runoff Coefficient for Urban Areas from the San Diego County Hydrology Manual will be utilized to determine the appropriate runoff coefficient based on the proposed use and the existing soils type.
The proposed development northerly of the right of way of Capalina Road drains to the north (West Mission Road) with the drainage leaving the site in two outlets to the existing curb and gutter along West Mission Road which flow to discharge point 1 at the projects northeasterly corner. The site improvements within the right of way of Capalina Road and consist of road widening, curb and gutter, driveway aprons and right of way improvements drains easterly to discharge point 2.
Downstream of the two discharge points, surface runoff continues easterly to the existing storm drain inlets located at North Pacific Street, the projects POC.
The pre-development onsite area is approximately 2.51 acre. The existing land use is undisturbed natural terrain. This determination was made based on a site inspection, aerial photography and a detailed aerial topography mapping. From table 3-1 “RUNOFF COEFFICIENTS FOR URBAN AREAs”, runoff coefficients for undisturbed natur al terrain will be used in the pre-development runoff calculations.
A pre-developed drainage map can be found as Attachment 4 in this report.
4.2 Post Conditions Topography and Drainage Patterns
This proposed project is a multifamily residential facility containing two buildings and associated surface parking and supporting utilities. Two biofiltration basins are proposed to mitigate the storm water quality for the project (BMP-A and BMP-B). BMP-A is located near the northeast corner of the site and BMP-B is located near the northwest corner of the site. The biofiltration basins will collect the storm water runoff from the building and proposed parking lots and convey the storm water through storage tanks, storm drain systems and curb and gutters to POC.
At the center of the project site, the proposed impervious area runoff is routed northerly to BMP-A then through the proposed 18 inches storm drain to the proposed 48 inches storage pipe system. After detention in said storage pipe system the system outflow through a 12 inches storm drain to discharge point 1, which is located at the northeast corner of the project site. BMP-A also has an emergency overflow which exits with a 12 inches storm drain to the same discharge point 1.
At the northwest part of the project site, surface runoff follows the proposed grades through curb cuts to BMP-B. BMP-B then drains through a 12 inches storm drain to a curb outlet at West Mission Road. These flows confluence with the existing surface flow along West Mission Road and drains easterly along the curb and gutter to the discharge point 1.
The south portion of the project site, The Capalina Road proposed improvements, drain easterly along the proposed curb and gutter, to discharge point 2, located at the southeast corner of the project site. After runoff leaves discharge point 1 and the discharge point 2, the drainage follows the existing curb and gutter to the east to the inlet in North Pacific Street, the project’s POC.
The land use type for the project site proposed condition was estimated based on aerial photography and detailed aerial topographic mapping to be High Density Residential 43.0 DU/A or less. From table 3-1 “RUNOFF COEFFICIENTS FOR URBAN AREAs ”, runoff coefficients for High Density Residential 43.0 DU/A or less will be used in the post- development runoff calculations.
As calculated below and summarized further in section 6, the pre-development discharges a peak 100-year flow of 5.627 CFS to Discharge Point 1, 1.571 CFS to Discharge Point 2, total 7.198 CFS to the project’s POC. The project proposed post-development discharge is a peak 100-year flow of 18.158 CFS to Discharge Point 1, 2.978 CFS to Discharge Point 2, for a total 21.136 CFS to POC , which needs storage and or detention upstream of the POC in post development design.
The mitigation system includes BMP-A and 224 ft of 48 inches RCP storage pipe to be installed as two 112 ft lengths. (Note: A third storage pipe is only used for hydromodification, not to peak flow). An 18 inches storm drain connects BMP-A to the storage pipe. The total storage volume of the storage pipe is 3067 cubic feet. The storage curve is shown in Figure 2 below.
Fig. 2 – Detention Pipe Storage Cuve
At the west side of the 2 barrels of 48 inches storage pipe, weir plate 1 provides flow control with an orifice at the bottom and a spillway at the top of weir plate 1. Orifice 1 is
1.39 ft in length and 0.125’ in height, and spillway 1 is 3.71 ft in length and 1.25 ft in height. The entire weir plate 1 is 48 inches in diameter. At the east end of the detention pipe, weir plate 2 which is 48 inches diameter is used to block water in the detention pipe.
HEC-HMS was used for routing the project flows. The area of the orifice and spillways input into HEC-HMS. The result of the routing shows that the project is mitigated from peak flow. The detailed routing results and hydrograph of HEC-HMS is in Attachment 7 of this study.
After mitigation, the peak 100-year flow of the post-development is reduced to 4.184 CFS at Discharge Point 1, for a total 7.162 CFS at the project’s POC. The onsite 48 inches storage pipes systems perform peak flow detention to mitigate POC. A post-developed drainage map can be found as Attachment 5 in this report.
4.3 Hydrologic Unit Contribution
The project site is located in Richland Hydrologic Sub Area of the San Marcos Hydrologic Area of the Carlsbad Hydrologic Unit (904.52).
5.0 Methodology
This report is prepared in accordance with the 2003 San Diego County Hydrology Manual.
Based on the overall tributary study area, calculations are based on the Rational Method.
5.1 Hydrology Software
We are using the CivilCadd /CivilDesign® software to analyze the runoff. The module we are using is the one for the San Diego County Flood Control Division 2003 Hydrology Manual. Please see the detailed hydrology calculations in Attachment 6.
5.2 Routing Software
Hydrologic Modeling System (HEC-HMS), Version 4.9 is used for hydrologic routing of the entire project site. The hydrograph developed from the rational method is then manually entered into this software and routed into each detention pipe. The HEC-HMS simulation results can be found in Attachment 7 in this report.
5.3 Soil Type Determination
The soil type for the proposed project was determined by mapping the project limits on the EPA Web Soil Survey website. The Web soil Survey indicate that the site is composed of soil type C and type D. The soil report and soil index map can be found in Attachment 3 of this report.
5.4 Isopluvial Value Determination
The isopluvial values for the 100-year 6 hour and 24 hour storm events were determined by plotting the projects location on the respective exhibits from Appendix B of the Hydrology Manual. The rainfall isopluvial maps can be found in Attachment 3 of this report.
6.0 Calculations
The intent of the post-development calculation done as part of this report is to verify the 100-year flowrates expected from the post-developed conditions are lower than the pre- developed conditions. These numbers will be used to size the proposed storm drainage pipes and to doublecheck if the existing storm drain outlet facilities are adequate.
6.1 Calculate Runoff Coefficient
The runoff coefficients for each of the drainage areas are taken from Table 3-1 of the Hydrology Manual. Based on the EPA Web Soil Survey, this project site is in type C and type D soil. The runoff coefficients C are based on the land use type for this project. Table 3-1 is included in the CIVILD software, and the values chosen based on the program input parameters. The output file was checked to ensure that the correct C values are used.
In order to not have a negative impact on the post development downstream facilities, a detention structure is needed for this project. The method used on the resulting values of the outflow hydrograph is to recalculate the runoff coefficient C value based on the fixed values of the outflow hydrograph to achieve a Cout . The detailed description and calculation of the Cout value can be found in Attachment 7 in this report.
6.2 Manning Roughness Coefficient
Manning Roughness Coefficients are taken from San Diego County Drainage Design Manual. Values are taken from Table A-1, Average Manning Roughness Coefficients for Pavement and Gutters, Table A-2, Average Manning Roughness Coefficients for Closed Conduits, and Table A-5, Average Manning roughness Coefficient for Natural Channels.
Values of 0.015 for Concrete Gutter, 0.013 for PVC Pipe, and 0.03 for Fairly Regular Section Some Grass and Weeds, Little or No Brush are used in the hydrology calculations.
Table of Manning’s n value can be found in Attachment 2 in this report.
6.3 Rational Method Calculation Summary
The peak runoff values for the 100-year storm are calculated according to the Hydrology Manual Rational Method. The calculations are performed using the CIVILD software. A summary of the initial calculations is summarized in the table below:
Summary of Q100 Runoff
PRE POST POST MITIGATION
Discharge
Point 1
Discharge
Point 2 POC
Discharge
Point 1
Discharge
Point 2 POC
Discharge
Point 1
Discharge
Point 2 POC
Q (CFS) 5.627 1.571 7.198 18.158 2.978 21.136 4.184 2.978 7.162 Tc
(MIN) 11.112 5.23 11.112 4.77 4.61 4.77 5.677 4.61 5.677 A
(ACRE) 2.7 0.398 3.098 2.675 0.423 3.098 2.673 0.42 3 3.096
Table 1. Q100 Analysis Results
Structures that used for detention consist of 48 inches storage pipes located at the northeast side of the project site within the project’s parking lot.
CIVILD data and output files can be found in Attachment 6 of this report.
By observation of the results in the summary table, the mitigated developed condition of the site will have an overall decrease in the 100-year peak flow discharge from the site.
7.0 Summary
This project will not negatively impact the existing downstream storm drain facilities.
Based on the results of this report, the project does not increase the 100-year peak flow rate of the Mitigated Post Development stormwater discharge from the site as flows are lower than those of the Pre Development condition.
8.0 References
County of San Diego, Department of Public Works, Flood Control Section, June 2003 San Diego County Hydrology Manual.
County of San Diego, Department of Public Works, Flood Control Section, September 2014 San Diego County Hydraulic Design Manual.
9.0 DECLARATION OF RESPONSIBLE CHARGE
I hereby declare that I am the engineer of work for this project. That I have exercised responsible charge over the design of the project as defined in section 6703 of the business and professions codes, and that the design is consistent with current design.
I understand that the check of the project drawings and specifications by the City of San Marcos is confined to a review only and does not relieve me, as engineer of work, of my responsibilities for project design.
ENGINEER OF WORK
Excel Engineering
440 State Place
Escondido, CA 92029
Tel – (760)745-8118
Fax – (760)745-1890
Project Number: 22-060
___________________________________________________ ____________ Robert D. Dentino, RCE 45629 Date
Registration Expire: December 31, 2024
ATTACHMENTS
Attachment 1 – Site Map
Attachment 2 – Figures & Tables from the San Diego County Hydrology Manual 2003
Attachment 3 – Watershed Information
Watershed Map
Soils Index Map
Soil Report
Rainfall Isopluvial Maps
Attachment 4 – Pre-Development Condition Exhibit
Attachment 5 – Post-Development Condition Exhibit
5a. Hydrology Map of Post-Development Condition Exhibit 5b. Hydrology Map of Post-Development Mitigation Condition Exhibit
Attachment 6 – Modified Rational Method Runoff Calculations 6a. CivilD Pre-Development Calculations
6b. CivilD Post-Development Calculations
6c. CivilD Mitigated Post-Development Calculations
Attachment 7 – Hydrograph
7a. HEC-HMS Simulation Results
7b. Runoff Coefficient C After Detention Structure
ATTACHMENT 1
SITE MAP
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SCALE: I ' 40"
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RILL/NC FNTFRPR/SFS
CAPAL/NA APARTMENTS
SIT£ MAP
ATTACHMENT 2
FIGURES & TABLES FROM THE SAN DIEGO COUNTY HYDROLOGY
MANUAL 2003
San Diego County Hydrology Manual Sect ion: 3
Date: June 2003 Page: 6 of 26
Table 3-1
RUNOFF COEFFICIENTS FOR URBAN AREAS
Land Use Runoff Coefficient “C”
Soil Type
NRCS Elements County Elements % IMPER. A B C D
Undisturbed Natural Terrain (Natural) Permanent Open Space 0* 0.20 0.25 0.30 0.35 Low Density Residential (LDR) Residential, 1.0 DU/A or less 10 0.27 0.32 0.36 0.41 Low Density Residential (LDR) Residential, 2.0 DU/A or less 20 0.34 0.38 0.42 0.46 Low Density Residential (LDR) Residential, 2.9 DU/A or less 25 0.38 0.41 0.45 0.49 Medium Density Residential (MDR) Residential, 4.3 DU/A or less 30 0.41 0.45 0.48 0.52 Medium Density Residential (MDR) Residential, 7.3 DU/A or less 40 0.48 0.51 0.54 0.57 Medium Density Residential (MDR) Residential, 10.9 DU/A or less 45 0.52 0.54 0.57 0.60 Medium Density Residential (MDR) Residential, 14.5 DU/A or less 50 0.55 0.58 0.60 0.63 High Density Residential (HDR) Residential, 24.0 DU/A or less 65 0.66 0.67 0.69 0.71 High Density Residential (HDR) Residential, 43.0 DU/A or less 80 0.76 0.77 0.78 0.79 Commercial/Industrial (N. Com) Neighborhood Commercial 80 0.76 0.77 0.78 0.79 Commercial/Industrial (G. Com) General Commercial 85 0.80 0.80 0.81 0.82 Commercial/Industrial (O.P. Com) Office Professional/Commercial 90 0.83 0.84 0.84 0.85 Commercial/Industrial (Limited I.) Limited Industrial 90 0.83 0.84 0.84 0.85 Commercial/Industrial (General I.) General Industrial 95 0.87 0.87 0.87 0.87
*The values associated with 0% impervious may be use d for direct calculation of the runoff coefficient as described in Section 3.1.2 (representing the pervious runoff coefficient, Cp, for the soil type), or for areas that will remain undisturbed in perpetuity. Justification must be given that the area will remain natural forever (e.g., the area is located in Cleveland National Forest).
DU/A = dwelling units per acre
NRCS = National Resources Conservation Service
3-6
San Diego County Hydrology Manual Section: 3
Date: June 2003 Page: 12 of 26
Note that the Initial Time of Concentration should be reflective of the general land-use at the upstream end of a drainage basin. A single lot with an area of two or less acres does not have a significant effect where the drainage basin area is 20 to 600 acres.
Table 3-2 provides lim its of the length (Maximum Length ( LM)) of sheet flow to be used in hydrology studies. Initial Ti values based on average C values for the Land Use Elem ent are also included. These values can b e used in planning and design applic ations a s described below. Exceptions m ay be approved by the “Regulating Agency” when subm itted with a detailed study.
Table 3-2
MAXIMUM OVERLAND FLOW LENGTH (LM)
& INITIAL TIME OF CONCENTRATION (Ti)
.5% 1% 2% 3% 5% 10% Element*
DU/
Acre LM Ti LM Ti LM Ti LM Ti LM Ti LM Ti
Natural 50 13.2 70 12.5 85 10.9 100 10.3 100 8.7 100 6.9 LDR 1 50 12.2 70 11.5 85 10.0 100 9.5 100 8.0 100 6.4
LDR 2 50 11.3 70 10.5 85 9.2 100 8.8 100 7.4 100 5.8
LDR 2.9 50 10.7 70 10.0 85 8.8 95 8.1 100 7.0 100 5.6
MDR 4.3 50 10.2 70 9.6 80 8.1 95 7.8 100 6.7 100 5.3
MDR 7.3 50 9.2 65 8.4 80 7.4 95 7.0 100 6.0 100 4.8
MDR 10.9 50 8.7 65 7.9 80 6.9 90 6.4 100 5.7 100 4.5
MDR 14.5 50 8.2 65 7.4 80 6.5 90 6.0 100 5.4 100 4.3
HDR 24 50 6.7 65 6.1 75 5.1 90 4.9 95 4.3 100 3.5
HDR 43 50 5.3 65 4.7 75 4.0 85 3.8 95 3.4 100 2.7
N. Com 50 5.3 60 4.5 75 4.0 85 3.8 95 3.4 100 2.7
G. Com 50 4.7 60 4.1 75 3.6 85 3.4 90 2.9 100 2.4
O.P./Com 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2
Limited I. 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2
General I. 50 3.7 60 3.2 70 2.7 80 2.6 90 2.3 100 1.9
*See Table 3-1 for more detailed description
3-12
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1.0 Intensity-Duration Design Chart - Template
Directions for Applicatio n:
(1) From precipitation maps determine 6 hr and 24 hr amounts for the selected frequency. These maps are included in the County Hydrology Manual (10, 50, and 100 yr maps included in the Design and Procedure Manual).
(2) Adjust 6 hr precipitation (if necessary) so that it is within the range of 45% to 65% of the 24 hr precipitation (not applicaple to Desert).
(3) Plot 6 hr precipitation on the right side of the chart . (4) Draw a line through the point parallel to the plotted lines. (5) This line is the intensity-duration curve for the location being analyzed .
Applicat ion Form:
(a) Selected frequency ___ year
p
(b) p6 = --- in., P24 = --- 'P 6 = %(2J
24 (c) Adjusted p6<2l = ___ in.
(d) tx = __ min .
(e) I = __ in./hr .
Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965.
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P6 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
Duration I I I I I I I I I I I
5 2.63 3.95 5.27 6.59 7.90 9.22 10.54 11.86 13.17 14.49 15.81 7 2.12 3.18 4.24 5.30 6.36 7.42 8.48 9.54 10.60 11.66 12.72 10 1.68 2.53 3.37 4.21 5.05 5.90 6.74 7.58 8.42 9.27 10.11 15 1.30 1.95 2.59 3.24 3.89 4.54 5.19 5.84 6.49 7.13 7.78 20 1.08 1.62 2.15 2.69 3.23 3.77 4.31 4.85 5.39 5.93 6.46 -25 0.93 1.40 1.87 2.33 2.80 3.27 3.73 4.20 4.67 5.13 5.60 30 0.83 1.24 1.66 2.07 2.49 2.90 3.32 3.73 4.15 4.56 4.98 ~ 0.69 1.03 1.38 1.72 2.0~ 2.41 2.76_ 3.10 3.45 3.79
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3-3
15 Nomograph for Determination of
Time of Concentration (Tc) or Travel Time (Tt) for Natural Watersheds 16 .6.E
Feet
5000
4000
Tc
Tc
L
.6.E
:::
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:::
=
EQUATION
(1~t)°·385
nme of concentration (hours)
Watercourse Distance (miles)
Change in elevation along
effective slope line (See Figure 3-S)(feet)
3000
2000
300
200
30 20
10 5
.6.E
SOURCE: California Division of Highways (1941} and Kirpich (1940) L
MIies Feet
0.5 L
4000
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'
2000
1800
1600
1400
1200
1000
900
800
700
600
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400
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200
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Tc
Hours Minutes
4 3
2 ' ' '
Tc
50 40
30 20
18 16
14 12
10 9
8 7
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FIGURE
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F I G U R E
SOURCE: California Division of Highways (1941) and Kirpich (1940) 3-5
Computation of Effective Slope for Natural Watersheds
Area “A” = Area “B”
Watershed Divide
Design
Point
Area “A”
Watershed
Divide
L
L
Design Point
(Watershed Outlet)
Stream Profile
Effective Slope Line
Area “B”
E
17 F I G U R E
SOURCE: San Diego County Department of Special District Services Design Manual 3-6
Gutter and Roadway Discharge - Velocity Chart
0.13 EXAMPLE:
Given: Q = 10 S = 2.5%
Chart gives: Depth = 0.4, Velocity = 4.4 f.p.s.
Depth RESIDENTIAL STREET
ONE SIDE ONLY
1.5’
n = .015
1 2 3 4 5 6 7 8 9 10 20 30 40 50
Discharge (C.F.S.)
0.4 0.5
0.6 0.7
0.8 0.9
1.0 1.2
1.4 1.6
1.8 2
3 6
4 5
7 8
9 10
12 14
16 18
20 V = 2.5 f.p.s.
V = 3 f.p.s.
V = 4 f.p.s.
V = 5 f.p.s.
V = 6 f.p.s.
V = 8 f.p.s.
V = 10 f.p.s. V = 12 f.p.s.
V = 2 f.p.s.
Depth 0.7 Feet
Depth 0.6 Feet
Depth 0.5 Feet
Depth 0.4 Feet
Depth 0.3 Feet
Depth 0.25 Feet
Depth 0.2 Feet
% of Street Slope
V = 1.5 f.p.s.
2%
2%
n = .0175
PavedConcrete
Gutter
18 F I G U R E
SOURCE: USDOT, FHWA, HDS-3 (1961)
3-7
Manning’s Equation Nomograph
s = 0.003
n = 0.02
SLOPE in feet per foot -s
HYDRAULIC RADIUS in feet - R
VELOCITY in feet per second - V
EXAMPLE
R=0.6
V=2.9
EQUATION: V = ____ R2/3 s1/21.49
n
0.3 0.2
0.15 0.10
0.09 0.08
0.07 0.06
0.05 0.04
0.03 0.02
0.01 0.009
0.008
0.007
0.006
0.005
0.004
0.003
0.002
0.0003
0.0004
0.0005
0.0006
0.0007
0.0008
0.0009
0.001
20 10
9 8
7 6
5 4
3 2
1.0 0.9
0.8 0.7
0.6 0.5
0.2 0.3
0.4 0.5
0.6 0.7
0.8 0.9
1.0 2
3 4
10 9
8 7
6 5
50 40
30 20
0.01 0.02
0.03 0.04
0.05 0.06
0.07 0.08
0.09 0.10
0.2 0.3
0.4 GENERAL SOLUTION
ROUGHNESS Coefficient - n
19 San Diego County Drainage Design Manual (July 2005)
Page A-3
Table A-1 Average Manning Roughness Coefficients for Pavement and Gutters1 Concrete Gutter2 ......................................................................................................................0.015 Concrete Pavement
Float Finish .........................................................................................................................0.014 Broom Finish.......................................................................................................................0.016 Concrete Gutter with Asphalt Pavement
Smooth Finish.....................................................................................................................0.013 Rough Texture ....................................................................................................................0.015 Asphalt Pavement
Smooth Finish.....................................................................................................................0.013 Rough Texture ....................................................................................................................0.016 Based on FHWA HEC-22.
1 Based on materials and workmanship required by standard specifications. 2 Increase roughness coefficient in gutters with mild slopes where sediment might accumulate by 0.020.
Table A-1
San Diego County Drainage Design Manual (July 2005)
Page A-4
Table A-2 Average Manning Roughness Coefficients for Closed Conduits3 Reinforced Concrete Pipe (RCP) .............................................................................................0.013 Corrugated Metal Pipe and Pipe Arch
2-3/8 x 1/2 inch Corrugations
Unlined ........................................................................................................................0.024 Half Lined
Full Flow ............................................................................................................... 0.018 d/D>=0.60 ............................................................................................................. 0.016 d/D<0.60 ............................................................................................................... 0.013 Fully Lined ................................................................................................................... 0.013 3 x 1 inch Corrugations ...................................................................................................... 0.027 6 x 2 inch Corrugations ...................................................................................................... 0.032 Spiral Rib Pipe ................................................................................................................... 0.013 Helically Wound Pipe
18-inch .........................................................................................................................0.015 24-inch .........................................................................................................................0.017 30-inch .........................................................................................................................0.019 36-inch .........................................................................................................................0.021 42-inch .........................................................................................................................0.022 48-inch .........................................................................................................................0.023 Plastic Pipe (HPDE and PVC)
Smooth ..............................................................................................................................0.013 Corrugated .........................................................................................................................0.024 Vitrified Clay Pipe .....................................................................................................................0.014 Cast-Iron Pipe (Uncoated) ....................................................................................................... 0.013 Steel Pipe ................................................................................................................................. 0.011 Brick ......................................................................................................................................... 0.017 Cast-In-Place Concrete Pipe
Rough Wood Forms .......................................................................................................... 0.017 Smooth Wood or Steel Forms ...........................................................................................0.014
3 Based on materials and workmanship required by standard specifications.
Table A-2
San Diego County Drainage Design Manual (July 2005)
Page A-6
Table A-5 Average Manning Roughness Coefficients for Natural Channels Minor Streams (Surface Width at Flood Stage < 100 ft)
Fairly Regular Section
(A) Some Grass and Weeds, Little or No Brush .........................................................0.030 (B) Dense Growth of Weeds, Depth of Flow Materially Greater Than Weed Height ....................................................................................................................0.040 (C) Some Weeds, Light Brush on Banks..................................................................... 0.040 (D) Some Weeds, Heavy Brush on Banks .................................................................. 0.060 (E) For Trees within Channel with Branches Submerge d at High Stage, Increase All Above Values By ..............................................................................................0.015 Irregular Section, with Pools, Slight Channel Meander
Channels (A) to (E) Above, Increase All Values By .....................................................0.015 Mountain Streams; No Vegetation in Channel, Banks Usually Steep, Trees and Brush along Banks Submerged at High Stage
(A) Bottom, Gravel, Cobbles and Few Boulders ..........................................................0.050 (B) Bottom, Cobbles with Large Boulders.................................................................... 0.060
Flood Plains (Adjacent To Natural Streams)
Pasture, No Brush
(A) Short Grass ............................................................................................................ 0.030 (B) High Grass ............................................................................................................. 0.040 Cultivated Areas
(A) No Crop .................................................................................................................. 0.040 (B) Mature Row Crops ................................................................................................. 0.040 (C) Mature Field Crops................................................................................................. 0.050 Heavy Weeds, Scattered Brush .........................................................................................0.050 Light Brush and Trees ........................................................................................................ 0.060 Medium To Dense Brush.................................................................................................... 0.090 Dense Willows ....................................................................................................................0.170 Cleared Land with Tree Stumps, 100-150 Per Acre...........................................................0.060 Heavy Stand of Timber, Little Undergrowth
(A) Flood Depth below Branches ................................................................................. 0.110 (B) Flood Depth Reaches Branches ............................................................................ 0.140
Table A-5
ATTACHMENT 3
WATERSHED INFORMATION
WATERSHED MAP
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SANTAMARGARITA
P A C I F I C O C E A N
R I V E R S I D E C O U N T Y
B A J A C A L I F O R N I A , M E X I C O
I M P E R I A L C O U N T Y
O R A N G E C O U N T Y
SAN JUAN SANTAMARGARITA
SANLUIS REY
SAN DIEGUITOCARLSBAD
SANDIEGOPENASQUITOS
SWEETWATERPUEBLOSAN DIEGO
SAN DIEGOBAY OTAY
TIJUANA
LAKEO'NEILL
LAKEPULGAS
MORRORESERVOIR
BECKRESERVOIR
REDMOUNTAINRESERVOIR
GUAJOME LAKE
LAKEHENSHAW
WINDMILLLAKE
SQUIRESDAM
TALONELAKE
HUBBERTLAKE TURNERLAKE
WHALENLAKE
CALAVERASLAKE
SANMARCOSLAKE
AQUAHEDIONDALAGOON
LAKEWOHLFORD
BUENAVISTALAGOON
DIXONRESERVOIR
SAN DIEGUITORESERVOIR
BATIQUITOSLAGOON
RESERVOIR
SANTEERECREATIONALLAKES LINDOLAKE
EL CAPITANRESERVOIR
SAN ELIJOLAGOON LAKEPOWAY
CORTEMADERALAKE
RESERVOIR25TH
MISSIONBAY
MIRAMARRESERVOIR
MORENARESERVOIRBARRETTLAKE
LAKERAMONA
MOUNTHELIXLAKE
LAKEMURRAY
HANSENRESERVOIR
LOWER OTAYRESERVOIR
SAN DIEGOBAY
LAKEHODGES
UPPER OTAYRESERVOIR
OLIVENHAINRESERVOIR
SANDIEGUITOLAGOON
LOSPENASQUITOSLAGOON
PALOVERDELAKE
LAKEJENNINGS
SANDIEGO
SANMARCOS
SANTEE
SOLANABEACH
VISTA
CARLSBAD
CHULAVISTA
CORONADO
DELMAR
EL CAJON
ENCINITAS
ESCONDIDO
IMPERIALBEACH
LA MESA
LEMONGROVE
NATIONALCITY
OCEANSIDE
POWAY
S.D.COUNTY
Tecate
Campo
BoulderOaks
PineValley
Descanso
Pala
Bonsall
PaumaValley
MesaGrande
SanOnofre
De Luz
Live OakPark
Rainbow
TwinOaks
Alpine
SpringValley
Jamacha
Jamul
RanchitaSanFelipe
Jacumba
Boulevard
GlenOaks
BankheadSprings
Ramona
SweeneyPass
OcotilloWells
AguaCalienteSprings
MountLaguna
TierraDel Sol
MorenaVillage
Julian
SantaYsabel
PalomarMountain
Potrero
Dehesa
Borrego Springs
Margarita
ValleyCenterJesmondDene
Fernbrook
BuckmanSprings
RinconSprings
BlossomValley
Dulzura
WarnerSprings
ScissorsCrossing
Cuyamaca
Lilac
Fallbrook
Guatay
HarbisonCanyon
CameronCorners
FelicitaRegionalPark
Flinn SpringsRegional Park
GopherCanyonReserve
Greenfield Blue Sky RanchEcologicalReserve
4-S RanchCommunityPark
AeriePark
AguaCalientePark
BerkeleyHeringPreserve
ChristopherHill (TET)
BorregoSpringsBorrego SpringsPark SiteDedication
Boulder OaksPreserve(South)
CactusPark
Cowles Mountain(Mission TrailsRegional Park)
DamonLanePark
DiamondTrail(TET)
Dos PicosRegionalPark
El CajonOperationsMaintenance Facility
El CapitanPreserve
GuajomeRegionalPark HellholeCanyonPreserve
In-Ko-PahPark
Sage HillPreserve
San Elijo LagoonEcologicalReserve
SantaMargaritaPreserve
SantaYsabel EastPreserveSantaYsabel WestPreserve
SimonPreserve
KnollwoodPreserve(TET)
LakeMorenaPark
LakesideBaseballPark LakesideLinkagePreserve
Lawrence andBarbara DaleyPreserve
Live OakPark
Luelf Pond /Holly OaksPreserve
MagdalenaEcke OpenSpace
MountOlympusPreserve
MountainSprings Park
Mt. GowerPreserve
Old SpringsRoad Preserve
Otay Mesa East(Marathon)(FurbyNorth)
Pala MesaMitigationProperty
QuailBotanicalGardens
Reams/Thomson
StelzerRegionalPark
Del DiosHighlandsPreserve
TijuanaRiver ValleyRegional Park
Val SerenoPreserve
Vallecito StageStation Regional Park& Historic Site
Valley CenterCommunity Park
Volcan MountainWildernessPreserve
WildernessGardensPreserve
Los PenasquitosCanyon Preserve
Santa FeValley OpenSpace Preserve
Goodan Ranch/SycamoreCanyon Preserve(Hagey 2011)
SweetwaterSummit ParkSweetwaterRegional Park
San DieguitoRegional Park
Otay P.O.M.Wolf Canyon
San Luis ReyRiverPark
Boulder OaksPreserve(North)
StoneridgePreserve PineValleyMSCP
RamonaGrasslandsPreserve
Otay RanchPreserve
Goodan Ranch/ SycamoreCanyon Preserve
MasonWildlifeRefuge
OakoasisPreserve
PotreroPark
EscondidoCreek
Otay ValleyRegionalPark
OtayRanchPOM
BarnettRanchPreserve
Bottle PeakPreserve
William HeiseRegional Park
El MonteRegionalParkHistoricFlumeCorridor
Lusardi CreekOpen SpacePreserve
I
San Diego CountyPacific Watersheds
0 4 8 1 2 2 M i l e s
P a t h : P : \ 2 0 1 4 1 2 2 4 _ P a c i f i c _ w a t e r s h e d s \ W a t e r s h e d s . m x d D a t e : 1 2 / 3 1 / 2 0 1 4 T H I S M A P / D A T A I S P R O V I D E D W I T H O U T W A R R A N T Y O F A N Y K I N D , E I T H E R E X P R E S S O R I M P L I E D , I N C L U D I N G B U T N O T L I M I T E D T O , T H E I M P L I E D W A R R A N T I E S O F M E R C H A N T A B I L I T Y A N D F I T N E S S F O R A P A R T I C U L A R P U R P O S E . N o t e : T h i s p r o d u c t m a y c o n t a i n i n f o r m a t i o n f r o m t h e S A N D A G R e g i o n a l I n f o r m a t i o n S y s t e m w h i c h c a n n o t b e r e p r o d u c e d w i t h o u t t h e w r i t t e n p e r m i s s i o n o f S A N D A G . T h i s p r o d u c t m a y c o n t a i n i n f o r m a t i o n r e p r o d u c e d w i t h p e r m i s s i o n g r a n t e d b y R a n d M c N a l l y & C o m p a n y ® t o S a n G I S . T h i s m a p i s c o p y r i g h t e d b y R a n d M c N a l l y & C o m p a n y ® . I t i s u n l a w f u l t o c o p y o r r e p r o d u c e a l l o r a n y p a r t t h e r e o f , w h e t h e r f o r p e r s o n a l u s e o r r e s a l e , w i t h o u t t h e p r i o r , w r i t t e n p e r m i s s i o n o f R a n d M c N a l l y & C o m p a n y ® . C o p y r i g h t S a n G I S 2 0 1 2 - A l l R i g h t s R e s e r v e d . F u l l t e x t o f t h i s l e g a l n o t i c e c a n b e f o u n d a t : h t t p : / / w w w . s a n g i s . o r g / L e g a l _ N o t i c e . h t m
SOIL INDEX MAP
/51/51/176/48/48/39
/51/50/176/52/53/39
/51/50/176/51/48/39
/51/51/176/49/53/39
/49/49/55/176/49/53/39 /49/49/55/176/48/48/39 /49/49/54/176/52/53/39 /49/49/54/176/51/48/39 /49/49/54/176/49/53/39 /49/49/54/176/51/48/39/49/49/54/176/52/53/39/49/49/55/176/48/48/39/49/49/55/176/49/53/39/49/49/55/176/51/48/39 /49/49/54/176/49/53/39 /51/51/176/49/53/39
/51/50/176/52/53/39
/51/51/176/48/48/39
/51/51/176/51/48/39
/51/50/176/51/48/39
/51/51/176/51/48/39
/49/49/55/176/51/48/39
/83/46/68/46/32/67/79/85/78/84/89
/83/65/78/32/68/73/69/71/79
/80/79/87/65/89
/67/72/85/76/65/32/86/73/83/84/65
/67/65/82/76/83/66/65/68
/79/67/69/65/78/83/73/68/69
/86/73/83/84/65
/69/83/67/79/78/68/73/68/79
/83/65/78/84/69/69
/69/78/67/73/78/73/84/65/83
/69/76/32/67/65/74/79/78
/67/79/82/79/78/65/68/79
/76/65/32/77/69/83/65
/73/77/80/69/82/73/65/76/32/66/69/65/67/72
/76/69/77/79/78/32/71/82/79/86/69
/83/79/76/65/78/65/32/66/69/65/67/72
/68/69/76/32/77/65/82
/82/105/118/101/114/115/105/100/101/32/67/111/117/110/116/121 /79/114/97/110/103/101/32
/67/111/117/110/116/121
/77/32/32/101/32/32/120/32/32/105/32/32/99/32/32/111
/73/109/112/101/114/105/97/108/32/67/111/117/110/116/121 /80/32/97/32/99/32/105/32/102/32/105/32/99/32/32/32/32/79/32/99/32/101/32/97/32/110 /33/34/94/36
/37/38/115/40
/33/34/95/36
/33/34/97/36
/65/168
/65/169
/65/169
/63/122
/65/192
/65/192
/63/104
/33/34/94/36
/51 /48 /51 /77/105/108/101/115
/78
/69/87
/83
/67/111/117/110/116/121/32/111/102/32/83/97/110/32/68/105/101/103/111 /72/121/100/114/111/108/111/103/121/32/77/97/110/117/97/108 /83/111/105/108/32/72/121/100/114/111/108/111/103/105/99/32/71/114/111/117/112/115 /76/101/103/101/110/100
/84/72/73/83/32/77/65/80/32/73/83/32/80/82/79/86/73/68/69/68/32/87/73/84/72/79/85/84/32/87/65/82/82/65/78/84/89/32/79/70/32/65/78/89/32/75/73/78/68/44/32/69/73/84/72/69/82/32/69/88/80/82/69/83/83 /79/82/32/73/77/80/76/73/69/68/44/32/73/78/67/76/85/68/73/78/71/44/32/66/85/84/32/78/79/84/32/76/73/77/73/84/69/68/32/84/79/44/32/84/72/69/32/73/77/80/76/73/69/68/32/87/65/82/82/65/78/84/73/69/83 /79/70/32/77/69/82/67/72/65/78/84/65/66/73/76/73/84/89/32/65/78/68/32/70/73/84/78/69/83/83/32/70/79/82/32/65/32/80/65/82/84/73/67/85/76/65/82/32/80/85/82/80/79/83/69/46 /67/111/112/121/114/105/103/104/116/32/83/97/110/71/73/83/46/32/65/108/108/32/82/105/103/104/116/115/32/82/101/115/101/114/118/101/100/46 /84/104/105/115/32/112/114/111/100/117/99/116/115/32/109/97/121/32/99/111/110/116/97/105/110/32/105/110/102/111/114/109/97/116/105/111/110/32/102/114/111/109/32/116/104/101/32/83/65/78/68/65/71/32/82/101/103/105/111/110/97/108 /73/110/102/111/114/109/97/116/105/111/110/32/83/121/115/116/101/109/32/119/104/105/99/104/32/99/97/110/110/111/116/32/98/101/32/114/101/112/114/111/100/117/99/101/100/32/119/105/116/104/111/117/116/32/116/104/101 /119/114/105/116/116/101/110/32/112/101/114/109/105/115/115/105/111/110/32/111/102/32/83/65/78/68/65/71/46 /84/104/105/115/32/112/114/111/100/117/99/116/32/109/97/121/32/99/111/110/116/97/105/110/32/105/110/102/111/114/109/97/116/105/111/110/32/119/104/105/99/104/32/104/97/115/32/98/101/101/110/32/114/101/112/114/111/100/117/99/101/100/32/119/105/116/104 /112/101/114/109/105/115/115/105/111/110/32/103/114/97/110/116/101/100/32/98/121/32/84/104/111/109/97/115/32/66/114/111/116/104/101/114/115/32/77/97/112/115/46 /83/111/105/108/32/71/114/111/117/112/115
/71/114/111/117/112/32/65
/71/114/111/117/112/32/66
/71/114/111/117/112/32/67
/71/114/111/117/112/32/68
/85/110/100/101/116/101/114/109/105/110/101/100
/68/97/116/97/32/85/110/97/118/97/105/108/97/98/108/101
SOIL REPORT
Hydrologic Soil Group—San Diego County Area, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
9/28/2022
3668030 3668050 3668070 3668090 36681 10 3668130 3668150 3668170 3668190 3668210 3668230 3668010 3668030 3668050 3668070 3668090 36681 10 3668130 3668150 3668170 3668190 3668210 3668230 481710 481730 481750 481770 481790 481810 481830 481850 481870 481710 481730 481750 481770 481790 481810 481830 481850 481870 33° 9' 9'' N
117° 11' 46'' W
33° 9' 9'' N
117° 11' 39'' W
33° 9' 2'' N
117° 11' 46'' W
33° 9' 2'' N
117° 11' 39'' W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 11N WGS84 0 50 100 200 300
Feet
0 15 30 60 90
Meters
Map Scale: 1:1,120 if printed on A portrait (8.5" x 11") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.
Soil Survey Area: San Diego County Area, California
Survey Area Data: Version 16, Sep 13, 2021
Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.
Date(s) aerial images were photographed: Mar 14, 2022—Mar 17, 2022
The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.
Hydrologic Soil Group—San Diego County Area, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
9/28/2022
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI DaC Diablo clay, 2 to 9
percent slopes
D 1.7 56.7%
DaD Diablo clay, 9 to 15
percent slopes, warm
MAAT
C 0.2 7.3%
LeC Las Flores loamy fine
sand, 2 to 9 percent
slopes
D 1.1 36.0%
Totals for Area of Interest 3.0 100.0%
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes.
Hydrologic Soil Group—San Diego County Area, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
9/28/2022
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—San Diego County Area, California Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
9/28/2022
RAINFALL ISOPLUVIAL MAPS
/51/51/176/48/48/39
/51/50/176/52/53/39
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PRE-DEVELOPMENT CONDITION EXHIBIT
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(589.00} ES
(587.12} ES
LEGEND
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■■■■■■■■■■ HYO BASIN BOI/NOARY
(%%,11 ES
I
E%/S77NC S/IRFACE £LEVA 770N
0 scALE.· 1 , 40,, r~
-- -- -- -0 40 80 120 160
RILLING ENTERPRISES CAPALINA
APARTMENTS PRE DEVilOPMENT
HYDROLOGY EXHIBIT
ATTACHMENT 5
POST-DEVELOPMENT CONDITION EXHIBIT
5a. Hydrology Map of Post-Development Condition Exhibit
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SURFACE FLOW
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HYO BASIN 80//NOARY
£)(/SllNC SURFACE EZEVAllON
flNISH SURFACE EZEVAllON
SCALE.· I ' 40"
0 40 80 !20 !60
RILL/NC ENTERPRISES CAPAL/NA
----·------~-- ,- - 1A APARTMENTS POST DEVELOPMENT
HYOROLOCY EXHIBIT
5b. Hydrology Map of Post-Development Mitigation Condition Exhibit
CAPALINA RD
W MISSION RD
ATTACHMENT 6
MODIFIED RATIONAL METHOD RUNOFF CALCULATIONS
Steps Taken To Analyze This Condition
The Rational Method Runoff Calculations are followed here. The software that we are using is the “Rational Hydrology Method, San Diego County (2003 Manual)” module of the CIVILCADD/CIVILDESIGN Engineering Software, Version 9.1.
Please see the subsequent pages for the calculations. These calculations are for the Q100 .
The results are outlined/summarized in Section 6.
6a. CivilD Pre-Development Calculations
1 2 San Diego County Rational Hydrology Program
3 4 CIVILCADD /CIVILDESIGN Engineering Software ,( c)1991 -2019 Version 9.1 5 6 Rational method hydrology program based on
7 San Diego County Flood Control Division 2003 hydrology manual 8 Rational Hydrology Study Date : 09 /29 /22
9 ------------------------------------------------------------------------ 10 11 22060 PRE DISCHARGE POINT 1
12 13
14 ------------------------------------------------------------------------ 15 ********* Hydrology Study Control Information ********** 16 17 ------------------------------------------------------------------------ 18 19
20 Program License Serial Number 6332
21 22 ------------------------------------------------------------------------ 23 Rational hydrology study storm event year is 100.0 24 English (in -lb ) input data Units used
25 26 Map data precipitation entered :
27 6 hour , precipitation (inches ) = 3.400
28 24 hour precipitation (inches ) = 5.700
29 P6 /P24 = 59.6%
30 San Diego hydrology manual 'C' values used
31 32
33 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 34 Process from Point /Station 101.000 to Point /Station 102.000 35 **** INITIAL AREA EVALUATION ****
36 ______________________________________________________________________ 37 Decimal fraction soil group A = 0.000
38 Decimal fraction soil group B = 0.000
39 Decimal fraction soil group C = 1.000
40 Decimal fraction soil group D = 0.000
41 [UNDISTURBED NATURAL TERRAIN ]
42 (Permanent Open Space )
43 Impervious value , Ai = 0.000
44 Sub -Area C Value = 0.300
45 Initial subarea total flow distance = 100.000 (Ft .) 46 Highest elevation = 601.000 (Ft .)
47 Lowest elevation = 597.300 (Ft .)
48 Elevation difference = 3.700 (Ft .) Slope = 3.700 % 49 INITIAL AREA TIME OF CONCENTRATION CALCULATIONS :
50 The maximum overland flow distance is 100.00 (Ft ) 51 for the top area slope value of 3.70 %, in a development type of 52 Permanent Open Space
53 In Accordance With Figure 3-3
54 Initial Area Time of Concentration = 9.31 minutes
55 TC = [1 .8*( 1.1 -C)* distance (Ft .) ^.5)/( % slope^ (1/3)] 56 TC = [1 .8*( 1.1 -0.3000 )*( 100.000^.5 )/( 3.700^ (1/3)]= 9.31 57 Rainfall intensity (I) = 5.999 (In /Hr ) for a 100.0 year storm 58 Effective runoff coefficient used for area (Q=KCIA ) is C = 0.300 59 Subarea runoff = 0.050 (CFS )
60 Total initial stream area = 0.028 (Ac .)
61 62
63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 64 Process from Point /Station 102.000 to Point /Station 103.000 65 **** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
66 ______________________________________________________________________ 67 Estimated mean flow rate at midpoint of channel = 2.277 (CFS ) 68 Depth of flow = 0.767 (Ft .), Average velocity = 3.867 (Ft /s) 69 ******* Irregular Channel Data ***********
70 ----------------------------------------------------------------- 71 Information entered for subchannel number 1 :
72 Point number 'X' coordinate 'Y' coordinate
73 1 0.00 1.00
74 2 1.00 0.00
75 3 2.00 1.00
76 Manning 's 'N' friction factor = 0.030
77 ----------------------------------------------------------------- 78 Sub -Channel flow = 2.277 (CFS )
79 ' ' flow top width = 1.535 (Ft .)
80 ' ' velocity = 3.867 (Ft /s)
81 ' ' area = 0.589 (Sq .Ft )
82 ' ' Froude number = 1.100
83 84 Upstream point elevation = 597.300 (Ft .)
85 Downstream point elevation = 582.790 (Ft .)
86 Flow length = 418.000 (Ft .)
87 Travel time = 1.80 min .
88 Time of concentration = 11.11 min .
89 Depth of flow = 0.767 (Ft .)
90 Average velocity = 3.867 (Ft /s)
91 Total irregular channel flow = 2.277 (CFS )
92 Irregular channel normal depth above invert elev . = 0.767 (Ft .) 93 Average velocity of channel (s) = 3.867 (Ft /s)
94 Adding area flow to channel
95 Rainfall intensity (I) = 5.352 (In /Hr ) for a 100.0 year storm 96 Decimal fraction soil group A = 0.000
97 Decimal fraction soil group B = 0.000
98 Decimal fraction soil group C = 0.000
99 Decimal fraction soil group D = 1.000
100 [UNDISTURBED NATURAL TERRAIN ]
101 (Permanent Open Space )
102 Impervious value , Ai = 0.000
103 Sub -Area C Value = 0.350
104 Rainfall intensity = 5.352 (In /Hr ) for a 100.0 year storm 105 Effective runoff coefficient used for total area
106 (Q=KCIA ) is C = 0.349 CA = 0.858
107 Subarea runoff = 4.541 (CFS ) for 2.427 (Ac .)
108 Total runoff = 4.591 (CFS ) Total area = 2.455 (Ac .) 109 Depth of flow = 0.998 (Ft .), Average velocity = 4.609 (Ft /s) 110
111
112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 113 Process from Point /Station 103.000 to Point /Station 103.000 114 **** CONFLUENCE OF MINOR STREAMS ****
115 ______________________________________________________________________ 116 Along Main Stream number : 1 in normal stream number 1 117 Stream flow area = 2.455 (Ac .)
118 Runoff from this stream = 4.591 (CFS )
119 Time of concentration = 11.11 min .
120 Rainfall intensity = 5.352 (In /Hr )
121
122
123 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 124 Process from Point /Station 201.000 to Point /Station 202.000 125 **** INITIAL AREA EVALUATION ****
126 ______________________________________________________________________ 127 Decimal fraction soil group A = 0.000
128 Decimal fraction soil group B = 0.000
129 Decimal fraction soil group C = 0.000
130 Decimal fraction soil group D = 1.000
131 [HIGH DENSITY RESIDENTIAL ]
132 (43.0 DU /A or Less )
133 Impervious value , Ai = 0.800
134 Sub -Area C Value = 0.790
135 Initial subarea total flow distance = 100.000 (Ft .) 136 Highest elevation = 589.000 (Ft .)
137 Lowest elevation = 587.420 (Ft .)
138 Elevation difference = 1.580 (Ft .) Slope = 1.580 % 139 INITIAL AREA TIME OF CONCENTRATION CALCULATIONS :
140 The maximum overland flow distance is 75.00 (Ft ) 141 for the top area slope value of 1.58 %, in a development type of 142 43.0 DU /A or Less
143 In Accordance With Figure 3-3
144 Initial Area Time of Concentration = 4.15 minutes 145 TC = [1 .8*( 1.1 -C)* distance (Ft .) ^.5)/( % slope^ (1/3)] 146 TC = [1 .8*( 1.1 -0.7900 )*( 75.000^.5 )/( 1.580^ (1/3)]= 4.15 147 Calculated TC of 4.149 minutes is less than 5 minutes , 148 resetting TC to 5.0 minutes for rainfall intensity calculations 149 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 150 Effective runoff coefficient used for area (Q=KCIA ) is C = 0.790 151 Subarea runoff = 0.729 (CFS )
152 Total initial stream area = 0.103 (Ac .)
153
154
155 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 156 Process from Point /Station 202.000 to Point /Station 103.000 157 **** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
158 ______________________________________________________________________ 159 Estimated mean flow rate at midpoint of channel = 1.188 (CFS ) 160 Depth of flow = 0.221 (Ft .), Average velocity = 2.398 (Ft /s) 161 ******* Irregular Channel Data ***********
162 ----------------------------------------------------------------- 163 Information entered for subchannel number 1 :
164 Point number 'X' coordinate 'Y' coordinate
165 1 0.00 0.50
166 2 0.00 0.00
167 3 1.30 0.11
168 4 19.00 0.50
169 Manning 's 'N' friction factor = 0.015
170 ----------------------------------------------------------------- 171 Sub -Channel flow = 1.188 (CFS )
172 ' ' flow top width = 6.338 (Ft .)
173 ' ' velocity = 2.398 (Ft /s)
174 ' ' area = 0.495 (Sq .Ft )
175 ' ' Froude number = 1.512
176
177 Upstream point elevation = 587.420 (Ft .)
178 Downstream point elevation = 582.790 (Ft .)
179 Flow length = 252.000 (Ft .)
180 Travel time = 1.75 min .
181 Time of concentration = 5.90 min .
182 Depth of flow = 0.221 (Ft .)
183 Average velocity = 2.398 (Ft /s)
184 Total irregular channel flow = 1.188 (CFS )
185 Irregular channel normal depth above invert elev . = 0.221 (Ft .) 186 Average velocity of channel (s) = 2.398 (Ft /s)
187 Adding area flow to channel
188 Rainfall intensity (I) = 8.051 (In /Hr ) for a 100.0 year storm 189 Decimal fraction soil group A = 0.000
190 Decimal fraction soil group B = 0.000
191 Decimal fraction soil group C = 0.000
192 Decimal fraction soil group D = 1.000
193 [HIGH DENSITY RESIDENTIAL ]
194 (43.0 DU /A or Less )
195 Impervious value , Ai = 0.800
196 Sub -Area C Value = 0.790
197 Rainfall intensity = 8.051 (In /Hr ) for a 100.0 year storm 198 Effective runoff coefficient used for total area
199 (Q=KCIA ) is C = 0.790 CA = 0.194
200 Subarea runoff = 0.829 (CFS ) for 0.142 (Ac .)
201 Total runoff = 1.558 (CFS ) Total area = 0.245 (Ac .) 202 Depth of flow = 0.238 (Ft .), Average velocity = 2.554 (Ft /s) 203
204
205 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 206 Process from Point /Station 103.000 to Point /Station 103.000 207 **** CONFLUENCE OF MINOR STREAMS ****
208 ______________________________________________________________________ 209 Along Main Stream number : 1 in normal stream number 2 210 Stream flow area = 0.245 (Ac .)
211 Runoff from this stream = 1.558 (CFS )
212 Time of concentration = 5.90 min .
213 Rainfall intensity = 8.051 (In /Hr )
214 Summary of stream data :
215
216 Stream Flow rate TC Rainfall Intensity
217 No . ( CFS ) ( min ) ( In /Hr )
218
219
220 1 4.591 11.11 5.352
221 2 1.558 5.90 8.051
222 Qmax (1) =
223 1.000 * 1.000 * 4.591 ) +
224 0.665 * 1.000 * 1.558 ) + = 5.627
225 Qmax (2) =
226 1.000 * 0.531 * 4.591 ) +
227 1.000 * 1.000 * 1.558 ) + = 3.996
228
229 Total of 2 streams to confluence :
230 Flow rates before confluence point :
231 4.591 1.558
232 Maximum flow rates at confluence using above data :
233 5.627 3.996
234 Area of streams before confluence :
235 2.455 0.245
236 Results of confluence :
237 Total flow rate = 5.627 (CFS )
238 Time of concentration = 11.112 min .
239 Effective stream area after confluence = 2.700 (Ac .) 240 End of computations , total study area = 2.700 (Ac .) 241
242
243
1 2 San Diego County Rational Hydrology Program
3 4 CIVILCADD /CIVILDESIGN Engineering Software ,( c)1991 -2019 Version 9.1 5 6 Rational method hydrology program based on
7 San Diego County Flood Control Division 2003 hydrology manual 8 Rational Hydrology Study Date : 09 /29 /22
9 ------------------------------------------------------------------------ 10 22060 PRE DISCHARGE POINT 2
11 12
13 14 ------------------------------------------------------------------------ 15 ********* Hydrology Study Control Information ********** 16 17 ------------------------------------------------------------------------ 18 19
20 Program License Serial Number 6332
21 22 ------------------------------------------------------------------------ 23 Rational hydrology study storm event year is 100.0 24 English (in -lb ) input data Units used
25 26 Map data precipitation entered :
27 6 hour , precipitation (inches ) = 3.400
28 24 hour precipitation (inches ) = 5.700
29 P6 /P24 = 59.6%
30 San Diego hydrology manual 'C' values used
31 32
33 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 34 Process from Point /Station 301.000 to Point /Station 302.000 35 **** INITIAL AREA EVALUATION ****
36 ______________________________________________________________________ 37 Decimal fraction soil group A = 0.000
38 Decimal fraction soil group B = 0.000
39 Decimal fraction soil group C = 1.000
40 Decimal fraction soil group D = 0.000
41 [HIGH DENSITY RESIDENTIAL ]
42 (43.0 DU /A or Less )
43 Impervious value , Ai = 0.800
44 Sub -Area C Value = 0.780
45 Initial subarea total flow distance = 100.000 (Ft .) 46 Highest elevation = 601.000 (Ft .)
47 Lowest elevation = 597.520 (Ft .)
48 Elevation difference = 3.480 (Ft .) Slope = 3.480 % 49 INITIAL AREA TIME OF CONCENTRATION CALCULATIONS :
50 The maximum overland flow distance is 85.00 (Ft )
51 for the top area slope value of 3.48 %, in a development type of 52 43.0 DU /A or Less
53 In Accordance With Figure 3-3
54 Initial Area Time of Concentration = 3.50 minutes
55 TC = [1 .8*( 1.1 -C)* distance (Ft .) ^.5)/( % slope^ (1/3)] 56 TC = [1 .8*( 1.1 -0.7800 )*( 85.000^.5 )/( 3.480^ (1/3)]= 3.50 57 Calculated TC of 3.504 minutes is less than 5 minutes , 58 resetting TC to 5.0 minutes for rainfall intensity calculations 59 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 60 Effective runoff coefficient used for area (Q=KCIA ) is C = 0.780 61 Subarea runoff = 0.671 (CFS )
62 Total initial stream area = 0.096 (Ac .)
63 64
65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 66 Process from Point /Station 302.000 to Point /Station 303.000 67 **** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
68 ______________________________________________________________________ 69 Estimated mean flow rate at midpoint of channel = 1.162 (CFS ) 70 Depth of flow = 0.598 (Ft .), Average velocity = 3.250 (Ft /s) 71 ******* Irregular Channel Data ***********
72 ----------------------------------------------------------------- 73 Information entered for subchannel number 1 :
74 Point number 'X' coordinate 'Y' coordinate
75 1 0.00 1.00
76 2 1.00 0.00
77 3 2.00 1.00
78 Manning 's 'N' friction factor = 0.030
79 ----------------------------------------------------------------- 80 Sub -Channel flow = 1.162 (CFS )
81 ' ' flow top width = 1.196 (Ft .)
82 ' ' velocity = 3.250 (Ft /s)
83 ' ' area = 0.358 (Sq .Ft )
84 ' ' Froude number = 1.047
85 86 Upstream point elevation = 597.520 (Ft .)
87 Downstream point elevation = 586.000 (Ft .)
88 Flow length = 337.000 (Ft .)
89 Travel time = 1.73 min .
90 Time of concentration = 5.23 min .
91 Depth of flow = 0.598 (Ft .)
92 Average velocity = 3.250 (Ft /s)
93 Total irregular channel flow = 1.162 (CFS )
94 Irregular channel normal depth above invert elev . = 0.598 (Ft .) 95 Average velocity of channel (s) = 3.250 (Ft /s)
96 Adding area flow to channel
97 Rainfall intensity (I) = 8.699 (In /Hr ) for a 100.0 year storm 98 Decimal fraction soil group A = 0.000
99 Decimal fraction soil group B = 0.000
100 Decimal fraction soil group C = 0.000
101 Decimal fraction soil group D = 1.000
102 [UNDISTURBED NATURAL TERRAIN ]
103 (Permanent Open Space )
104 Impervious value , Ai = 0.000
105 Sub -Area C Value = 0.350
106 Rainfall intensity = 8.699 (In /Hr ) for a 100.0 year storm 107 Effective runoff coefficient used for total area
108 (Q=KCIA ) is C = 0.454 CA = 0.181
109 Subarea runoff = 0.900 (CFS ) for 0.302 (Ac .)
110 Total runoff = 1.571 (CFS ) Total area = 0.398 (Ac .) 111 Depth of flow = 0.670 (Ft .), Average velocity = 3.504 (Ft /s) 112 End of computations , total study area = 0.398 (Ac .) 113
114
115
6b. CivilD Post-Development Calculations
1 2 San Diego County Rational Hydrology Program
3 4 CIVILCADD /CIVILDESIGN Engineering Software ,( c)1991 -2019 Version 9.1 5 6 Rational method hydrology program based on
7 San Diego County Flood Control Division 2003 hydrology manual 8 Rational Hydrology Study Date : 04 /06 /23
9 ------------------------------------------------------------------------ 10 22060 POST DISCHARGE POINT 1
11 12
13 14 ------------------------------------------------------------------------ 15 ********* Hydrology Study Control Information ********** 16 17 ------------------------------------------------------------------------ 18 19
20 Program License Serial Number 6332
21 22 ------------------------------------------------------------------------ 23 Rational hydrology study storm event year is 100.0 24 English (in -lb ) input data Units used
25 26 Map data precipitation entered :
27 6 hour , precipitation (inches ) = 3.400
28 24 hour precipitation (inches ) = 5.700
29 P6 /P24 = 59.6%
30 San Diego hydrology manual 'C' values used
31 32
33 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 34 Process from Point /Station 101.000 to Point /Station 102.000 35 **** INITIAL AREA EVALUATION ****
36 ______________________________________________________________________ 37 Decimal fraction soil group A = 0.000
38 Decimal fraction soil group B = 0.000
39 Decimal fraction soil group C = 0.000
40 Decimal fraction soil group D = 1.000
41 [HIGH DENSITY RESIDENTIAL ]
42 (43.0 DU /A or Less )
43 Impervious value , Ai = 0.800
44 Sub -Area C Value = 0.790
45 Initial subarea total flow distance = 100.000 (Ft .) 46 Highest elevation = 598.420 (Ft .)
47 Lowest elevation = 596.140 (Ft .)
48 Elevation difference = 2.280 (Ft .) Slope = 2.280 % 49 INITIAL AREA TIME OF CONCENTRATION CALCULATIONS :
50 The maximum overland flow distance is 75.00 (Ft )
51 for the top area slope value of 2.28 %, in a development type of 52 43.0 DU /A or Less
53 In Accordance With Figure 3-3
54 Initial Area Time of Concentration = 3.67 minutes
55 TC = [1 .8*( 1.1 -C)* distance (Ft .) ^.5)/( % slope^ (1/3)] 56 TC = [1 .8*( 1.1 -0.7900 )*( 75.000^.5 )/( 2.280^ (1/3)]= 3.67 57 Calculated TC of 3.672 minutes is less than 5 minutes , 58 resetting TC to 5.0 minutes for rainfall intensity calculations 59 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 60 Effective runoff coefficient used for area (Q=KCIA ) is C = 0.790 61 Subarea runoff = 0.863 (CFS )
62 Total initial stream area = 0.122 (Ac .)
63 64
65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 66 Process from Point /Station 102.000 to Point /Station 103.000 67 **** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
68 ______________________________________________________________________ 69 Estimated mean flow rate at midpoint of channel = 5.761 (CFS ) 70 Depth of flow = 1.164 (Ft .), Average velocity = 7.312 (Ft /s) 71 ******* Irregular Channel Data ***********
72 ----------------------------------------------------------------- 73 Information entered for subchannel number 1 :
74 Point number 'X' coordinate 'Y' coordinate
75 1 0.00 1.42
76 2 56.50 1.29
77 3 58.00 0.00
78 4 58.00 0.50
79 Manning 's 'N' friction factor = 0.015
80 ----------------------------------------------------------------- 81 Sub -Channel flow = 5.761 (CFS )
82 ' ' flow top width = 1.354 (Ft .)
83 ' ' velocity = 7.312 (Ft /s)
84 ' ' area = 0.788 (Sq .Ft )
85 ' ' Froude number = 1.689
86 87 Upstream point elevation = 596.140 (Ft .)
88 Downstream point elevation = 587.530 (Ft .)
89 Flow length = 382.000 (Ft .)
90 Travel time = 0.87 min .
91 Time of concentration = 4.54 min .
92 Depth of flow = 1.164 (Ft .)
93 Average velocity = 7.312 (Ft /s)
94 Total irregular channel flow = 5.761 (CFS )
95 Irregular channel normal depth above invert elev . = 1.164 (Ft .) 96 Average velocity of channel (s) = 7.312 (Ft /s)
97 Adding area flow to channel
98 Calculated TC of 4.542 minutes is less than 5 minutes , 99 resetting TC to 5.0 minutes for rainfall intensity calculations 100 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 101 Decimal fraction soil group A = 0.000
102 Decimal fraction soil group B = 0.000
103 Decimal fraction soil group C = 0.000
104 Decimal fraction soil group D = 1.000
105 [HIGH DENSITY RESIDENTIAL ]
106 (43.0 DU /A or Less )
107 Impervious value , Ai = 0.800
108 Sub -Area C Value = 0.790
109 Rainfall intensity = 8.958 (In /Hr ) for a 100.0 year storm 110 Effective runoff coefficient used for total area
111 (Q=KCIA ) is C = 0.790 CA = 1.190
112 Subarea runoff = 9.794 (CFS ) for 1.384 (Ac .)
113 Total runoff = 10.658 (CFS ) Total area = 1.506 (Ac .) 114 Depth of flow = 1.403 (Ft .), Average velocity = 2.648 (Ft /s) 115
116
117 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 118 Process from Point /Station 106.000 to Point /Station 103.000 119 **** SUBAREA FLOW ADDITION ****
120 ______________________________________________________________________ 121 Calculated TC of 4.542 minutes is less than 5 minutes , 122 resetting TC to 5.0 minutes for rainfall intensity calculations 123 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 124 Decimal fraction soil group A = 0.000
125 Decimal fraction soil group B = 0.000
126 Decimal fraction soil group C = 0.000
127 Decimal fraction soil group D = 1.000
128 [HIGH DENSITY RESIDENTIAL ]
129 (43.0 DU /A or Less )
130 Impervious value , Ai = 0.800
131 Sub -Area C Value = 0.790
132 Time of concentration = 4.54 min .
133 Rainfall intensity = 8.958 (In /Hr ) for a 100.0 year storm 134 Effective runoff coefficient used for total area
135 (Q=KCIA ) is C = 0.790 CA = 1.502
136 Subarea runoff = 2.795 (CFS ) for 0.395 (Ac .)
137 Total runoff = 13.453 (CFS ) Total area = 1.901 (Ac .) 138
139
140 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 141 Process from Point /Station 107.000 to Point /Station 103.000 142 **** SUBAREA FLOW ADDITION ****
143 ______________________________________________________________________ 144 Calculated TC of 4.542 minutes is less than 5 minutes , 145 resetting TC to 5.0 minutes for rainfall intensity calculations 146 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 147 Decimal fraction soil group A = 0.000
148 Decimal fraction soil group B = 0.000
149 Decimal fraction soil group C = 0.000
150 Decimal fraction soil group D = 1.000
151 [HIGH DENSITY RESIDENTIAL ]
152 (43.0 DU /A or Less )
153 Impervious value , Ai = 0.800
154 Sub -Area C Value = 0.790
155 Time of concentration = 4.54 min .
156 Rainfall intensity = 8.958 (In /Hr ) for a 100.0 year storm 157 Effective runoff coefficient used for total area
158 (Q=KCIA ) is C = 0.790 CA = 1.589
159 Subarea runoff = 0.786 (CFS ) for 0.111 (Ac .)
160 Total runoff = 14.239 (CFS ) Total area = 2.012 (Ac .) 161
162
163 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 164 Process from Point /Station 108.000 to Point /Station 103.000 165 **** SUBAREA FLOW ADDITION ****
166 ______________________________________________________________________ 167 Calculated TC of 4.542 minutes is less than 5 minutes , 168 resetting TC to 5.0 minutes for rainfall intensity calculations 169 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 170 Decimal fraction soil group A = 0.000
171 Decimal fraction soil group B = 0.000
172 Decimal fraction soil group C = 0.000
173 Decimal fraction soil group D = 1.000
174 [HIGH DENSITY RESIDENTIAL ]
175 (43.0 DU /A or Less )
176 Impervious value , Ai = 0.800
177 Sub -Area C Value = 0.790
178 Time of concentration = 4.54 min .
179 Rainfall intensity = 8.958 (In /Hr ) for a 100.0 year storm 180 Effective runoff coefficient used for total area
181 (Q=KCIA ) is C = 0.790 CA = 1.732
182 Subarea runoff = 1.274 (CFS ) for 0.180 (Ac .)
183 Total runoff = 15.513 (CFS ) Total area = 2.192 (Ac .) 184
185
186 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 187 Process from Point /Station 103.000 to Point /Station 104.000 188 **** PIPEFLOW TRAVEL TIME (User specified size ) **** 189 ______________________________________________________________________ 190 Upstream point /station elevation = 585.100 (Ft .) 191 Downstream point /station elevation = 584.810 (Ft .) 192 Pipe length = 58.00 (Ft .) Slope = 0.0050 Manning 's N = 0.013 193 No . of pipes = 1 Required pipe flow = 15.513 (CFS ) 194 Given pipe size = 18.00 (In .)
195 NOTE : Normal flow is pressure flow in user selected pipe size . 196 The approximate hydraulic grade line above the pipe invert is 197 2.769 (Ft .) at the headworks or inlet of the pipe (s) 198 Pipe friction loss = 1.264 (Ft .)
199 Minor friction loss = 1.795 (Ft .) K-factor = 1.50 200 Pipe flow velocity = 8.78 (Ft /s)
201 Travel time through pipe = 0.11 min .
202 Time of concentration (TC ) = 4.65 min .
203
204
205 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 206 Process from Point /Station 104.000 to Point /Station 105.000 207 **** PIPEFLOW TRAVEL TIME (User specified size ) **** 208 ______________________________________________________________________ 209 Upstream point /station elevation = 583.790 (Ft .) 210 Downstream point /station elevation = 583.020 (Ft .) 211 Pipe length = 139.00 (Ft .) Slope = 0.0055 Manning 's N = 0.013 212 No . of pipes = 1 Required pipe flow = 15.513 (CFS ) 213 Given pipe size = 12.00 (In .)
214 NOTE : Normal flow is pressure flow in user selected pipe size . 215 The approximate hydraulic grade line above the pipe invert is 216 34.659 (Ft .) at the headworks or inlet of the pipe (s) 217 Pipe friction loss = 26.342 (Ft .)
218 Minor friction loss = 9.086 (Ft .) K-factor = 1.50 219 Pipe flow velocity = 19.75 (Ft /s)
220 Travel time through pipe = 0.12 min .
221 Time of concentration (TC ) = 4.77 min .
222
223
224 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 225 Process from Point /Station 105.000 to Point /Station 105.000 226 **** CONFLUENCE OF MAIN STREAMS ****
227 ______________________________________________________________________ 228 The following data inside Main Stream is listed :
229 In Main Stream number : 1
230 Stream flow area = 2.192 (Ac .)
231 Runoff from this stream = 15.513 (CFS )
232 Time of concentration = 4.77 min .
233 Rainfall intensity = 8.958 (In /Hr )
234 Program is now starting with Main Stream No . 2
235
236
237 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 238 Process from Point /Station 201.000 to Point /Station 202.000 239 **** INITIAL AREA EVALUATION ****
240 ______________________________________________________________________ 241 Decimal fraction soil group A = 0.000
242 Decimal fraction soil group B = 0.000
243 Decimal fraction soil group C = 0.000
244 Decimal fraction soil group D = 1.000
245 [HIGH DENSITY RESIDENTIAL ]
246 (43.0 DU /A or Less )
247 Impervious value , Ai = 0.800
248 Sub -Area C Value = 0.790
249 Initial subarea total flow distance = 144.000 (Ft .) 250 Highest elevation = 594.410 (Ft .)
251 Lowest elevation = 591.500 (Ft .)
252 Elevation difference = 2.910 (Ft .) Slope = 2.021 % 253 Top of Initial Area Slope adjusted by User to 1.674 % 254 INITIAL AREA TIME OF CONCENTRATION CALCULATIONS :
255 The maximum overland flow distance is 75.00 (Ft ) 256 for the top area slope value of 1.67 %, in a development type of 257 43.0 DU /A or Less
258 In Accordance With Figure 3-3
259 Initial Area Time of Concentration = 4.07 minutes 260 TC = [1 .8*( 1.1 -C)* distance (Ft .) ^.5)/( % slope^ (1/3)] 261 TC = [1 .8*( 1.1 -0.7900 )*( 75.000^.5 )/( 1.674^ (1/3)]= 4.07 262 Calculated TC of 4.070 minutes is less than 5 minutes , 263 resetting TC to 5.0 minutes for rainfall intensity calculations 264 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 265 Effective runoff coefficient used for area (Q=KCIA ) is C = 0.790 266 Subarea runoff = 1.260 (CFS )
267 Total initial stream area = 0.178 (Ac .)
268
269
270 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 271 Process from Point /Station 202.000 to Point /Station 203.000 272 **** PIPEFLOW TRAVEL TIME (User specified size ) **** 273 ______________________________________________________________________ 274 Upstream point /station elevation = 587.600 (Ft .) 275 Downstream point /station elevation = 587.530 (Ft .) 276 Pipe length = 14.00 (Ft .) Slope = 0.0050 Manning 's N = 0.013 277 No . of pipes = 1 Required pipe flow = 1.260 (CFS ) 278 Given pipe size = 12.00 (In .)
279 Calculated individual pipe flow = 1.260 (CFS )
280 Normal flow depth in pipe = 6.00 (In .)
281 Flow top width inside pipe = 12.00 (In .)
282 Critical Depth = 5.69 (In .)
283 Pipe flow velocity = 3.21 (Ft /s)
284 Travel time through pipe = 0.07 min .
285 Time of concentration (TC ) = 4.14 min .
286
287
288 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 289 Process from Point /Station 203.000 to Point /Station 203.000 290 **** CONFLUENCE OF MINOR STREAMS ****
291 ______________________________________________________________________ 292 Along Main Stream number : 2 in normal stream number 1 293 Stream flow area = 0.178 (Ac .)
294 Runoff from this stream = 1.260 (CFS )
295 Time of concentration = 4.14 min .
296 Rainfall intensity = 8.958 (In /Hr )
297
298
299 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 300 Process from Point /Station 301.000 to Point /Station 302.000 301 **** INITIAL AREA EVALUATION ****
302 ______________________________________________________________________ 303 Decimal fraction soil group A = 0.000
304 Decimal fraction soil group B = 0.000
305 Decimal fraction soil group C = 0.000
306 Decimal fraction soil group D = 1.000
307 [HIGH DENSITY RESIDENTIAL ]
308 (43.0 DU /A or Less )
309 Impervious value , Ai = 0.800
310 Sub -Area C Value = 0.790
311 Initial subarea total flow distance = 100.000 (Ft .) 312 Highest elevation = 589.000 (Ft .)
313 Lowest elevation = 587.610 (Ft .)
314 Elevation difference = 1.390 (Ft .) Slope = 1.390 % 315 Top of Initial Area Slope adjusted by User to 1.620 % 316 INITIAL AREA TIME OF CONCENTRATION CALCULATIONS :
317 The maximum overland flow distance is 75.00 (Ft ) 318 for the top area slope value of 1.62 %, in a development type of 319 43.0 DU /A or Less
320 In Accordance With Figure 3-3
321 Initial Area Time of Concentration = 4.11 minutes 322 TC = [1 .8*( 1.1 -C)* distance (Ft .) ^.5)/( % slope^ (1/3)] 323 TC = [1 .8*( 1.1 -0.7900 )*( 75.000^.5 )/( 1.620^ (1/3)]= 4.11 324 Calculated TC of 4.115 minutes is less than 5 minutes , 325 resetting TC to 5.0 minutes for rainfall intensity calculations 326 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 327 Effective runoff coefficient used for area (Q=KCIA ) is C = 0.790 328 Subarea runoff = 0.701 (CFS )
329 Total initial stream area = 0.099 (Ac .)
330
331
332 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 333 Process from Point /Station 302.000 to Point /Station 203.000 334 **** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
335 ______________________________________________________________________ 336 Depth of flow = 0.244 (Ft .), Average velocity = 1.068 (Ft /s) 337 ******* Irregular Channel Data ***********
338 ----------------------------------------------------------------- 339 Information entered for subchannel number 1 :
340 Point number 'X' coordinate 'Y' coordinate
341 1 0.00 0.50
342 2 0.00 0.00
343 3 1.30 0.11
344 4 19.00 0.50
345 Manning 's 'N' friction factor = 0.015
346 ----------------------------------------------------------------- 347 Sub -Channel flow = 0.701 (CFS )
348 ' ' flow top width = 7.397 (Ft .)
349 ' ' velocity = 1.069 (Ft /s)
350 ' ' area = 0.656 (Sq .Ft )
351 ' ' Froude number = 0.632
352
353 Upstream point elevation = 587.610 (Ft .)
354 Downstream point elevation = 587.570 (Ft .)
355 Flow length = 13.000 (Ft .)
356 Travel time = 0.20 min .
357 Time of concentration = 4.32 min .
358 Depth of flow = 0.244 (Ft .)
359 Average velocity = 1.068 (Ft /s)
360 Total irregular channel flow = 0.701 (CFS )
361 Irregular channel normal depth above invert elev . = 0.244 (Ft .) 362 Average velocity of channel (s) = 1.068 (Ft /s)
363
364
365 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 366 Process from Point /Station 203.000 to Point /Station 203.000 367 **** CONFLUENCE OF MINOR STREAMS ****
368 ______________________________________________________________________ 369 Along Main Stream number : 2 in normal stream number 2 370 Stream flow area = 0.099 (Ac .)
371 Runoff from this stream = 0.701 (CFS )
372 Time of concentration = 4.32 min .
373 Rainfall intensity = 8.958 (In /Hr )
374 Summary of stream data :
375
376 Stream Flow rate TC Rainfall Intensity
377 No . ( CFS ) ( min ) ( In /Hr )
378
379
380 1 1.260 4.14 8.958
381 2 0.701 4.32 8.958
382 Qmax (1) =
383 1.000 * 1.000 * 1.260 ) +
384 1.000 * 0.960 * 0.701 ) + = 1.932
385 Qmax (2) =
386 1.000 * 1.000 * 1.260 ) +
387 1.000 * 1.000 * 0.701 ) + = 1.960
388
389 Total of 2 streams to confluence :
390 Flow rates before confluence point :
391 1.260 0.701
392 Maximum flow rates at confluence using above data :
393 1.932 1.960
394 Area of streams before confluence :
395 0.178 0.099
396 Results of confluence :
397 Total flow rate = 1.960 (CFS )
398 Time of concentration = 4.317 min .
399 Effective stream area after confluence = 0.277 (Ac .) 400
401
402 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 403 Process from Point /Station 203.000 to Point /Station 105.000 404 **** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
405 ______________________________________________________________________ 406 Estimated mean flow rate at midpoint of channel = 2.589 (CFS ) 407 Depth of flow = 0.274 (Ft .), Average velocity = 2.905 (Ft /s) 408 ******* Irregular Channel Data ***********
409 ----------------------------------------------------------------- 410 Information entered for subchannel number 1 :
411 Point number 'X' coordinate 'Y' coordinate
412 1 0.00 0.50
413 2 0.00 0.00
414 3 1.30 0.11
415 4 19.00 0.50
416 Manning 's 'N' friction factor = 0.015
417 ----------------------------------------------------------------- 418 Sub -Channel flow = 2.589 (CFS )
419 ' ' flow top width = 8.724 (Ft .)
420 ' ' velocity = 2.905 (Ft /s)
421 ' ' area = 0.891 (Sq .Ft )
422 ' ' Froude number = 1.602
423
424 Upstream point elevation = 587.570 (Ft .)
425 Downstream point elevation = 583.120 (Ft .)
426 Flow length = 237.000 (Ft .)
427 Travel time = 1.36 min .
428 Time of concentration = 5.68 min .
429 Depth of flow = 0.274 (Ft .)
430 Average velocity = 2.905 (Ft /s)
431 Total irregular channel flow = 2.589 (CFS )
432 Irregular channel normal depth above invert elev . = 0.274 (Ft .) 433 Average velocity of channel (s) = 2.905 (Ft /s)
434 Adding area flow to channel
435 Rainfall intensity (I) = 8.254 (In /Hr ) for a 100.0 year storm 436 Decimal fraction soil group A = 0.000
437 Decimal fraction soil group B = 0.000
438 Decimal fraction soil group C = 0.000
439 Decimal fraction soil group D = 1.000
440 [HIGH DENSITY RESIDENTIAL ]
441 (43.0 DU /A or Less )
442 Impervious value , Ai = 0.800
443 Sub -Area C Value = 0.790
444 Rainfall intensity = 8.254 (In /Hr ) for a 100.0 year storm 445 Effective runoff coefficient used for total area
446 (Q=KCIA ) is C = 0.790 CA = 0.382
447 Subarea runoff = 1.189 (CFS ) for 0.206 (Ac .)
448 Total runoff = 3.149 (CFS ) Total area = 0.483 (Ac .) 449 Depth of flow = 0.289 (Ft .), Average velocity = 3.045 (Ft /s) 450
451
452 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 453 Process from Point /Station 105.000 to Point /Station 105.000 454 **** CONFLUENCE OF MAIN STREAMS ****
455 ______________________________________________________________________ 456 The following data inside Main Stream is listed :
457 In Main Stream number : 2
458 Stream flow area = 0.483 (Ac .)
459 Runoff from this stream = 3.149 (CFS )
460 Time of concentration = 5.68 min .
461 Rainfall intensity = 8.254 (In /Hr )
462 Summary of stream data :
463
464 Stream Flow rate TC Rainfall Intensity
465 No . ( CFS ) ( min ) ( In /Hr )
466
467
468 1 15.513 4.77 8.958
469 2 3.149 5.68 8.254
470 Qmax (1) =
471 1.000 * 1.000 * 15.513 ) +
472 1.000 * 0.840 * 3.149 ) + = 18.158
473 Qmax (2) =
474 0.921 * 1.000 * 15.513 ) +
475 1.000 * 1.000 * 3.149 ) + = 17.442
476
477 Total of 2 main streams to confluence :
478 Flow rates before confluence point :
479 15.513 3.149
480 Maximum flow rates at confluence using above data :
481 18.158 17.442
482 Area of streams before confluence :
483 2.192 0.483
484
485
486 Results of confluence :
487 Total flow rate = 18.158 (CFS )
488 Time of concentration = 4.770 min .
489 Effective stream area after confluence = 2.675 (Ac .) 490 End of computations , total study area = 2.675 (Ac .) 491
492
493
1 2 San Diego County Rational Hydrology Program
3 4 CIVILCADD /CIVILDESIGN Engineering Software ,( c)1991 -2019 Version 9.1 5 6 Rational method hydrology program based on
7 San Diego County Flood Control Division 2003 hydrology manual 8 Rational Hydrology Study Date : 01 /09 /23
9 ------------------------------------------------------------------------ 10 22060 POST DISCHARGE POINT 1
11 HYDROGRAPH FOR BMP A
12 13
14 ------------------------------------------------------------------------ 15 ********* Hydrology Study Control Information ********** 16 17 ------------------------------------------------------------------------ 18 19
20 Program License Serial Number 6332
21 22 ------------------------------------------------------------------------ 23 Rational hydrology study storm event year is 100.0 24 English (in -lb ) input data Units used
25 26 Map data precipitation entered :
27 6 hour , precipitation (inches ) = 3.400
28 24 hour precipitation (inches ) = 5.700
29 P6 /P24 = 59.6%
30 San Diego hydrology manual 'C' values used
31 32
33 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 34 Process from Point /Station 101.000 to Point /Station 102.000 35 **** INITIAL AREA EVALUATION ****
36 ______________________________________________________________________ 37 Decimal fraction soil group A = 0.000
38 Decimal fraction soil group B = 0.000
39 Decimal fraction soil group C = 0.000
40 Decimal fraction soil group D = 1.000
41 [HIGH DENSITY RESIDENTIAL ]
42 (43.0 DU /A or Less )
43 Impervious value , Ai = 0.800
44 Sub -Area C Value = 0.790
45 Initial subarea total flow distance = 100.000 (Ft .) 46 Highest elevation = 598.420 (Ft .)
47 Lowest elevation = 596.140 (Ft .)
48 Elevation difference = 2.280 (Ft .) Slope = 2.280 % 49 INITIAL AREA TIME OF CONCENTRATION CALCULATIONS :
50 The maximum overland flow distance is 75.00 (Ft )
51 for the top area slope value of 2.28 %, in a development type of 52 43.0 DU /A or Less
53 In Accordance With Figure 3-3
54 Initial Area Time of Concentration = 3.67 minutes
55 TC = [1 .8*( 1.1 -C)* distance (Ft .) ^.5)/( % slope^ (1/3)] 56 TC = [1 .8*( 1.1 -0.7900 )*( 75.000^.5 )/( 2.280^ (1/3)]= 3.67 57 Calculated TC of 3.672 minutes is less than 5 minutes , 58 resetting TC to 5.0 minutes for rainfall intensity calculations 59 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 60 Effective runoff coefficient used for area (Q=KCIA ) is C = 0.790 61 Subarea runoff = 0.863 (CFS )
62 Total initial stream area = 0.122 (Ac .)
63 64
65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 66 Process from Point /Station 102.000 to Point /Station 103.000 67 **** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
68 ______________________________________________________________________ 69 Estimated mean flow rate at midpoint of channel = 5.761 (CFS ) 70 Depth of flow = 1.164 (Ft .), Average velocity = 7.312 (Ft /s) 71 ******* Irregular Channel Data ***********
72 ----------------------------------------------------------------- 73 Information entered for subchannel number 1 :
74 Point number 'X' coordinate 'Y' coordinate
75 1 0.00 1.42
76 2 56.50 1.29
77 3 58.00 0.00
78 4 58.00 0.50
79 Manning 's 'N' friction factor = 0.015
80 ----------------------------------------------------------------- 81 Sub -Channel flow = 5.761 (CFS )
82 ' ' flow top width = 1.354 (Ft .)
83 ' ' velocity = 7.312 (Ft /s)
84 ' ' area = 0.788 (Sq .Ft )
85 ' ' Froude number = 1.689
86 87 Upstream point elevation = 596.140 (Ft .)
88 Downstream point elevation = 587.530 (Ft .)
89 Flow length = 382.000 (Ft .)
90 Travel time = 0.87 min .
91 Time of concentration = 4.54 min .
92 Depth of flow = 1.164 (Ft .)
93 Average velocity = 7.312 (Ft /s)
94 Total irregular channel flow = 5.761 (CFS )
95 Irregular channel normal depth above invert elev . = 1.164 (Ft .) 96 Average velocity of channel (s) = 7.312 (Ft /s)
97 Adding area flow to channel
98 Calculated TC of 4.542 minutes is less than 5 minutes , 99 resetting TC to 5.0 minutes for rainfall intensity calculations 100 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 101 Decimal fraction soil group A = 0.000
102 Decimal fraction soil group B = 0.000
103 Decimal fraction soil group C = 0.000
104 Decimal fraction soil group D = 1.000
105 [HIGH DENSITY RESIDENTIAL ]
106 (43.0 DU /A or Less )
107 Impervious value , Ai = 0.800
108 Sub -Area C Value = 0.790
109 Rainfall intensity = 8.958 (In /Hr ) for a 100.0 year storm 110 Effective runoff coefficient used for total area
111 (Q=KCIA ) is C = 0.790 CA = 1.190
112 Subarea runoff = 9.794 (CFS ) for 1.384 (Ac .)
113 Total runoff = 10.658 (CFS ) Total area = 1.506 (Ac .) 114 Depth of flow = 1.403 (Ft .), Average velocity = 2.648 (Ft /s) 115
116
117 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 118 Process from Point /Station 106.000 to Point /Station 103.000 119 **** SUBAREA FLOW ADDITION ****
120 ______________________________________________________________________ 121 Calculated TC of 4.542 minutes is less than 5 minutes , 122 resetting TC to 5.0 minutes for rainfall intensity calculations 123 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 124 Decimal fraction soil group A = 0.000
125 Decimal fraction soil group B = 0.000
126 Decimal fraction soil group C = 0.000
127 Decimal fraction soil group D = 1.000
128 [HIGH DENSITY RESIDENTIAL ]
129 (43.0 DU /A or Less )
130 Impervious value , Ai = 0.800
131 Sub -Area C Value = 0.790
132 Time of concentration = 4.54 min .
133 Rainfall intensity = 8.958 (In /Hr ) for a 100.0 year storm 134 Effective runoff coefficient used for total area
135 (Q=KCIA ) is C = 0.790 CA = 1.502
136 Subarea runoff = 2.795 (CFS ) for 0.395 (Ac .)
137 Total runoff = 13.453 (CFS ) Total area = 1.901 (Ac .) 138
139
140 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 141 Process from Point /Station 107.000 to Point /Station 103.000 142 **** SUBAREA FLOW ADDITION ****
143 ______________________________________________________________________ 144 Calculated TC of 4.542 minutes is less than 5 minutes , 145 resetting TC to 5.0 minutes for rainfall intensity calculations 146 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 147 Decimal fraction soil group A = 0.000
148 Decimal fraction soil group B = 0.000
149 Decimal fraction soil group C = 0.000
150 Decimal fraction soil group D = 1.000
151 [HIGH DENSITY RESIDENTIAL ]
152 (43.0 DU /A or Less )
153 Impervious value , Ai = 0.800
154 Sub -Area C Value = 0.790
155 Time of concentration = 4.54 min .
156 Rainfall intensity = 8.958 (In /Hr ) for a 100.0 year storm 157 Effective runoff coefficient used for total area
158 (Q=KCIA ) is C = 0.790 CA = 1.589
159 Subarea runoff = 0.786 (CFS ) for 0.111 (Ac .)
160 Total runoff = 14.239 (CFS ) Total area = 2.012 (Ac .) 161
162
163 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 164 Process from Point /Station 108.000 to Point /Station 103.000 165 **** SUBAREA FLOW ADDITION ****
166 ______________________________________________________________________ 167 Calculated TC of 4.542 minutes is less than 5 minutes , 168 resetting TC to 5.0 minutes for rainfall intensity calculations 169 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 170 Decimal fraction soil group A = 0.000
171 Decimal fraction soil group B = 0.000
172 Decimal fraction soil group C = 0.000
173 Decimal fraction soil group D = 1.000
174 [HIGH DENSITY RESIDENTIAL ]
175 (43.0 DU /A or Less )
176 Impervious value , Ai = 0.800
177 Sub -Area C Value = 0.790
178 Time of concentration = 4.54 min .
179 Rainfall intensity = 8.958 (In /Hr ) for a 100.0 year storm 180 Effective runoff coefficient used for total area
181 (Q=KCIA ) is C = 0.790 CA = 1.732
182 Subarea runoff = 1.274 (CFS ) for 0.180 (Ac .)
183 Total runoff = 15.513 (CFS ) Total area = 2.192 (Ac .) 184
185
186 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 187 Process from Point /Station 101.000 to Point /Station 103.000 188 **** 6 HOUR HYDROGRAPH ****
189 ______________________________________________________________________ 190 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 191 Hydrograph Data - Section 6, San Diego County Hydrology manual , June 2003 192
193
194 Time of Concentration = 4.54
195 Basin Area = 2.19 Acres
196 6 Hour Rainfall = 3.400 Inches
197 Runoff Coefficient = 0.790
198 Peak Discharge = 15.51 CFS
199 Time (Min ) Discharge (CFS )
200 0 0.000
201 4 0.350
202 8 0.353
203 12 0.358
204 16 0.361
205 20 0.366
206 24 0.369
207 28 0.375
208 32 0.378
209 36 0.384
210 40 0.388
211 44 0.394
212 48 0.398
213 52 0.405
214 56 0.409
215 60 0.416
216 64 0.420
217 68 0.428
218 72 0.433
219 76 0.442
220 80 0.446
221 84 0.456
222 88 0.461
223 92 0.471
224 96 0.477
225 100 0.488
226 104 0.494
227 108 0.507
228 112 0.513
229 116 0.527
230 120 0.534
231 124 0.550
232 128 0.558
233 132 0.575
234 136 0.584
235 140 0.604
236 144 0.614
237 148 0.636
238 152 0.648
239 156 0.673
240 160 0.687
241 164 0.717
242 168 0.733
243 172 0.768
244 176 0.787
245 180 0.830
246 184 0.854
247 188 0.907
248 192 0.936
249 196 1.004
250 200 1.043
251 204 1.134
252 208 1.187
253 212 1.316
254 216 1.396
255 220 1.600
256 224 1.735
257 228 2.121
258 232 2.416
259 236 3.547
260 240 4.998
261 244 15.513
262 248 2.845
263 252 1.903
264 256 1.489
265 260 1.247
266 264 1.086
267 268 0.969
268 272 0.879
269 276 0.808
270 280 0.750
271 284 0.702
272 288 0.660
273 292 0.625
274 296 0.594
275 300 0.566
276 304 0.542
277 308 0.520
278 312 0.500
279 316 0.482
280 320 0.466
281 324 0.451
282 328 0.437
283 332 0.424
284 336 0.412
285 340 0.401
286 344 0.391
287 348 0.381
288 352 0.372
289 356 0.364
290 360 0.355
291 364 0.348
292 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 293 6 - H O U R S T O R M
294 R u n o f f H y d r o g r a p h
295 -------------------------------------------------------------------- 296 Hydrograph in 1 Minute intervals (( CFS ))
297
298 -------------------------------------------------------------------- 299 Time (h+m) Volume Ac .Ft Q (CFS ) 0 3.9 7.8 11.6 15.5 300 ----------------------------------------------------------------------- 301 0+ 0 0.0000 0.00 Q | | | |
302 0+ 1 0.0001 0.09 Q | | | |
303 0+ 2 0.0004 0.18 Q | | | |
304 0+ 3 0.0007 0.26 Q | | | |
305 0+ 4 0.0012 0.35 Q | | | |
306 0+ 5 0.0017 0.35 Q | | | |
307 0+ 6 0.0022 0.35 Q | | | |
308 0+ 7 0.0027 0.35 Q | | | |
309 0+ 8 0.0031 0.35 Q | | | |
310 0+ 9 0.0036 0.35 Q | | | |
311 0+10 0.0041 0.36 Q | | | |
312 0+11 0.0046 0.36 Q | | | |
313 0+12 0.0051 0.36 Q | | | |
314 0+13 0.0056 0.36 Q | | | |
315 0+14 0.0061 0.36 Q | | | |
316 0+15 0.0066 0.36 Q | | | |
317 0+16 0.0071 0.36 Q | | | |
318 0+17 0.0076 0.36 Q | | | |
319 0+18 0.0081 0.36 Q | | | |
320 0+19 0.0086 0.36 Q | | | |
321 0+20 0.0091 0.37 Q | | | |
322 0+21 0.0096 0.37 Q | | | |
323 0+22 0.0101 0.37 Q | | | |
324 0+23 0.0106 0.37 Q | | | |
325 0+24 0.0111 0.37 Q | | | |
326 0+25 0.0116 0.37 Q | | | |
327 0+26 0.0121 0.37 QV | | | |
328 0+27 0.0127 0.37 QV | | | |
329 0+28 0.0132 0.38 QV | | | |
330 0+29 0.0137 0.38 QV | | | |
331 0+30 0.0142 0.38 QV | | | |
332 0+31 0.0147 0.38 QV | | | |
333 0+32 0.0153 0.38 QV | | | |
334 0+33 0.0158 0.38 QV | | | |
335 0+34 0.0163 0.38 QV | | | |
336 0+35 0.0168 0.38 QV | | | |
337 0+36 0.0174 0.38 QV | | | |
338 0+37 0.0179 0.39 QV | | | |
339 0+38 0.0184 0.39 QV | | | |
340 0+39 0.0190 0.39 QV | | | |
341 0+40 0.0195 0.39 QV | | | |
342 0+41 0.0200 0.39 |Q | | | |
343 0+42 0.0206 0.39 |Q | | | |
344 0+43 0.0211 0.39 |Q | | | |
345 0+44 0.0217 0.39 |Q | | | |
346 0+45 0.0222 0.40 |Q | | | |
347 0+46 0.0227 0.40 |Q | | | |
348 0+47 0.0233 0.40 |Q | | | |
349 0+48 0.0238 0.40 |QV | | | |
350 0+49 0.0244 0.40 |QV | | | |
351 0+50 0.0249 0.40 |QV | | | |
352 0+51 0.0255 0.40 |QV | | | |
353 0+52 0.0261 0.40 |QV | | | |
354 0+53 0.0266 0.41 |QV | | | |
355 0+54 0.0272 0.41 |QV | | | |
356 0+55 0.0277 0.41 |QV | | | |
357 0+56 0.0283 0.41 |QV | | | |
358 0+57 0.0289 0.41 |QV | | | |
359 0+58 0.0294 0.41 |QV | | | |
360 0+59 0.0300 0.41 |QV | | | |
361 1+ 0 0.0306 0.42 |QV | | | |
362 1+ 1 0.0311 0.42 |QV | | | |
363 1+ 2 0.0317 0.42 |QV | | | |
364 1+ 3 0.0323 0.42 |QV | | | |
365 1+ 4 0.0329 0.42 |QV | | | |
366 1+ 5 0.0335 0.42 |QV | | | |
367 1+ 6 0.0340 0.42 |QV | | | |
368 1+ 7 0.0346 0.43 |QV | | | |
369 1+ 8 0.0352 0.43 |QV | | | |
370 1+ 9 0.0358 0.43 |Q V | | | |
371 1+10 0.0364 0.43 |Q V | | | |
372 1+11 0.0370 0.43 |Q V | | | |
373 1+12 0.0376 0.43 |Q V | | | |
374 1+13 0.0382 0.43 |Q V | | | |
375 1+14 0.0388 0.44 |Q V | | | |
376 1+15 0.0394 0.44 |Q V | | | |
377 1+16 0.0400 0.44 |Q V | | | |
378 1+17 0.0406 0.44 |Q V | | | |
379 1+18 0.0412 0.44 |Q V | | | |
380 1+19 0.0419 0.45 |Q V | | | |
381 1+20 0.0425 0.45 |Q V | | | |
382 1+21 0.0431 0.45 |Q V | | | |
383 1+22 0.0437 0.45 |Q V | | | |
384 1+23 0.0443 0.45 |Q V | | | |
385 1+24 0.0450 0.46 |Q V | | | |
386 1+25 0.0456 0.46 |Q V | | | |
387 1+26 0.0462 0.46 |Q V | | | |
388 1+27 0.0469 0.46 |Q V | | | |
389 1+28 0.0475 0.46 |Q V | | | |
390 1+29 0.0481 0.46 |Q V | | | |
391 1+30 0.0488 0.47 |Q V | | | |
392 1+31 0.0494 0.47 |Q V | | | |
393 1+32 0.0501 0.47 |Q V | | | |
394 1+33 0.0507 0.47 |Q V | | | |
395 1+34 0.0514 0.47 |Q V | | | |
396 1+35 0.0520 0.48 |Q V | | | |
397 1+36 0.0527 0.48 |Q V | | | |
398 1+37 0.0533 0.48 |Q V | | | |
399 1+38 0.0540 0.48 |Q V | | | |
400 1+39 0.0547 0.49 |Q V | | | |
401 1+40 0.0553 0.49 |Q V | | | |
402 1+41 0.0560 0.49 |Q V | | | |
403 1+42 0.0567 0.49 |Q V | | | |
404 1+43 0.0574 0.49 |Q V | | | |
405 1+44 0.0581 0.49 |Q V | | | |
406 1+45 0.0587 0.50 |Q V | | | |
407 1+46 0.0594 0.50 |Q V | | | |
408 1+47 0.0601 0.50 |Q V | | | |
409 1+48 0.0608 0.51 |Q V | | | |
410 1+49 0.0615 0.51 |Q V | | | |
411 1+50 0.0622 0.51 |Q V | | | |
412 1+51 0.0629 0.51 |Q V | | | |
413 1+52 0.0636 0.51 |Q V | | | |
414 1+53 0.0643 0.52 |Q V | | | |
415 1+54 0.0651 0.52 |Q V | | | |
416 1+55 0.0658 0.52 |Q V | | | |
417 1+56 0.0665 0.53 |Q V | | | |
418 1+57 0.0672 0.53 |Q V | | | |
419 1+58 0.0680 0.53 |Q V | | | |
420 1+59 0.0687 0.53 |Q V | | | |
421 2+ 0 0.0694 0.53 |Q V | | | |
422 2+ 1 0.0702 0.54 |Q V | | | |
423 2+ 2 0.0709 0.54 |Q V | | | |
424 2+ 3 0.0717 0.55 |Q V | | | |
425 2+ 4 0.0724 0.55 |Q V | | | |
426 2+ 5 0.0732 0.55 |Q V | | | |
427 2+ 6 0.0740 0.55 |Q V | | | |
428 2+ 7 0.0747 0.56 |Q V | | | |
429 2+ 8 0.0755 0.56 |Q V | | | |
430 2+ 9 0.0763 0.56 |Q V | | | |
431 2+10 0.0771 0.57 |Q V | | | |
432 2+11 0.0778 0.57 |Q V | | | |
433 2+12 0.0786 0.58 |Q V | | | |
434 2+13 0.0794 0.58 |Q V | | | |
435 2+14 0.0802 0.58 |Q V | | | |
436 2+15 0.0810 0.58 |Q V | | | |
437 2+16 0.0818 0.58 |Q V | | | |
438 2+17 0.0826 0.59 |Q V | | | |
439 2+18 0.0835 0.59 |Q V | | | |
440 2+19 0.0843 0.60 |Q V | | | |
441 2+20 0.0851 0.60 |Q V | | | |
442 2+21 0.0860 0.61 |Q V | | | |
443 2+22 0.0868 0.61 |Q V | | | |
444 2+23 0.0876 0.61 |Q V | | | |
445 2+24 0.0885 0.61 |Q V | | | |
446 2+25 0.0893 0.62 |Q V | | | |
447 2+26 0.0902 0.63 |Q V | | | |
448 2+27 0.0911 0.63 |Q V | | | |
449 2+28 0.0919 0.64 |Q V | | | |
450 2+29 0.0928 0.64 |Q V | | | |
451 2+30 0.0937 0.64 |Q V | | | |
452 2+31 0.0946 0.64 |Q V | | | |
453 2+32 0.0955 0.65 |Q V | | | |
454 2+33 0.0964 0.65 |Q V | | | |
455 2+34 0.0973 0.66 |Q V | | | |
456 2+35 0.0982 0.67 |Q V | | | |
457 2+36 0.0991 0.67 |Q V | | | |
458 2+37 0.1001 0.68 |Q V | | | |
459 2+38 0.1010 0.68 |Q V | | | |
460 2+39 0.1020 0.68 |Q V | | | |
461 2+40 0.1029 0.69 |Q V | | | |
462 2+41 0.1039 0.69 |Q V | | | |
463 2+42 0.1048 0.70 |Q V | | | |
464 2+43 0.1058 0.71 |Q V | | | |
465 2+44 0.1068 0.72 |Q V | | | |
466 2+45 0.1078 0.72 |Q V | | | |
467 2+46 0.1088 0.72 |Q V | | | |
468 2+47 0.1098 0.73 |Q V | | | |
469 2+48 0.1108 0.73 |Q V | | | |
470 2+49 0.1118 0.74 |Q V | | | |
471 2+50 0.1128 0.75 |Q V | | | |
472 2+51 0.1139 0.76 |Q V | | | |
473 2+52 0.1149 0.77 |Q V | | | |
474 2+53 0.1160 0.77 |Q V | | | |
475 2+54 0.1171 0.78 | Q V | | | |
476 2+55 0.1182 0.78 | Q V | | | |
477 2+56 0.1192 0.79 | Q V | | |
478 2+57 0.1203 0.80 | Q V | | |
479 2+58 0.1215 0.81 | Q V | | |
480 2+59 0.1226 0.82 | Q V | | |
481 3+ 0 0.1237 0.83 | Q V | | |
482 3+ 1 0.1249 0.84 | Q V | | |
483 3+ 2 0.1260 0.84 | Q V | | |
484 3+ 3 0.1272 0.85 | Q V | | |
485 3+ 4 0.1284 0.85 | Q V | | |
486 3+ 5 0.1296 0.87 | Q V | | |
487 3+ 6 0.1308 0.88 | Q |V | | |
488 3+ 7 0.1320 0.89 | Q |V | | |
489 3+ 8 0.1333 0.91 | Q |V | | |
490 3+ 9 0.1345 0.91 | Q |V | | |
491 3+10 0.1358 0.92 | Q |V | | |
492 3+11 0.1371 0.93 | Q |V | | |
493 3+12 0.1384 0.94 | Q |V | | |
494 3+13 0.1397 0.95 | Q |V | | |
495 3+14 0.1410 0.97 | Q |V | | |
496 3+15 0.1424 0.99 | Q |V | | |
497 3+16 0.1438 1.00 | Q | V | | |
498 3+17 0.1452 1.01 | Q | V | | |
499 3+18 0.1466 1.02 | Q | V | | |
500 3+19 0.1480 1.03 | Q | V | | |
501 3+20 0.1494 1.04 | Q | V | | |
502 3+21 0.1509 1.07 | Q | V | | |
503 3+22 0.1524 1.09 | Q | V | | |
504 3+23 0.1539 1.11 | Q | V | | |
505 3+24 0.1555 1.13 | Q | V | | |
506 3+25 0.1571 1.15 | Q | V | | |
507 3+26 0.1587 1.16 | Q | V | | |
508 3+27 0.1603 1.17 | Q | V | | |
509 3+28 0.1619 1.19 | Q | V | | |
510 3+29 0.1636 1.22 | Q | V | | |
511 3+30 0.1653 1.25 | Q | V | | |
512 3+31 0.1671 1.28 | Q | V | | |
513 3+32 0.1689 1.32 | Q | V | | |
514 3+33 0.1707 1.34 | Q | V | | |
515 3+34 0.1726 1.36 | Q | V | | |
516 3+35 0.1745 1.38 | Q | V | | |
517 3+36 0.1764 1.40 | Q | V | | |
518 3+37 0.1784 1.45 | Q | V | | |
519 3+38 0.1805 1.50 | Q | V | | |
520 3+39 0.1826 1.55 | Q | V | | |
521 3+40 0.1848 1.60 | Q | V | | |
522 3+41 0.1871 1.63 | Q | V | | |
523 3+42 0.1894 1.67 | Q | V | | |
524 3+43 0.1917 1.70 | Q | V | | |
525 3+44 0.1941 1.74 | Q | V | | |
526 3+45 0.1966 1.83 | Q | V | | |
527 3+46 0.1993 1.93 | Q | V | | |
528 3+47 0.2021 2.02 | Q | V | | |
529 3+48 0.2050 2.12 | Q | V | | |
530 3+49 0.2080 2.19 | Q | V | | |
531 3+50 0.2111 2.27 | Q | V | | |
532 3+51 0.2144 2.34 | Q | V | | |
533 3+52 0.2177 2.42 | Q | V | | |
534 3+53 0.2214 2.70 | Q | V | | |
535 3+54 0.2255 2.98 | Q | V | | |
536 3+55 0.2300 3.26 | Q | V| | |
537 3+56 0.2349 3.55 | Q| V| | |
538 3+57 0.2403 3.91 | Q V | |
539 3+58 0.2462 4.27 | | Q V | |
540 3+59 0.2526 4.64 | | Q |V | |
541 4+ 0 0.2594 5.00 | | Q |V | |
542 4+ 1 0.2699 7.63 | | Q| V | |
543 4+ 2 0.2841 10.26 | | | V Q | |
544 4+ 3 0.3018 12.88 | | | V | Q |
545 4+ 4 0.3232 15.51 | | | V | Q
546 4+ 5 0.3402 12.35 | | | V |Q |
547 4+ 6 0.3528 9.18 | | | Q V | |
548 4+ 7 0.3611 6.01 | | Q | V |
549 4+ 8 0.3650 2.84 | Q | | V |
550 4+ 9 0.3686 2.61 | Q | | | V |
551 4+10 0.3719 2.37 | Q | | | V |
552 4+11 0.3748 2.14 | Q | | | V |
553 4+12 0.3775 1.90 | Q | | | V |
554 4+13 0.3799 1.80 | Q | | | V |
555 4+14 0.3823 1.70 | Q | | | V |
556 4+15 0.3845 1.59 | Q | | | V |
557 4+16 0.3865 1.49 | Q | | | V |
558 4+17 0.3885 1.43 | Q | | | V |
559 4+18 0.3904 1.37 | Q | | | V |
560 4+19 0.3922 1.31 | Q | | | V |
561 4+20 0.3939 1.25 | Q | | | V |
562 4+21 0.3956 1.21 | Q | | | V |
563 4+22 0.3972 1.17 | Q | | | V |
564 4+23 0.3987 1.13 | Q | | | V |
565 4+24 0.4002 1.09 | Q | | | V |
566 4+25 0.4017 1.06 | Q | | | V |
567 4+26 0.4031 1.03 | Q | | | V |
568 4+27 0.4045 1.00 | Q | | | V |
569 4+28 0.4058 0.97 | Q | | | V |
570 4+29 0.4071 0.95 | Q | | | V |
571 4+30 0.4084 0.92 | Q | | | V |
572 4+31 0.4096 0.90 | Q | | | V |
573 4+32 0.4108 0.88 | Q | | | V |
574 4+33 0.4120 0.86 | Q | | | V |
575 4+34 0.4132 0.84 | Q | | | V |
576 4+35 0.4143 0.83 | Q | | | V |
577 4+36 0.4154 0.81 | Q | | | V |
578 4+37 0.4165 0.79 | Q | | | V |
579 4+38 0.4176 0.78 | Q | | | V |
580 4+39 0.4186 0.76 |Q | | | V |
581 4+40 0.4197 0.75 |Q | | | V |
582 4+41 0.4207 0.74 |Q | | | V |
583 4+42 0.4217 0.73 |Q | | | V |
584 4+43 0.4227 0.71 |Q | | | V |
585 4+44 0.4236 0.70 |Q | | | V |
586 4+45 0.4246 0.69 |Q | | | V |
587 4+46 0.4255 0.68 |Q | | | V |
588 4+47 0.4265 0.67 |Q | | | V |
589 4+48 0.4274 0.66 |Q | | | V |
590 4+49 0.4283 0.65 |Q | | | V |
591 4+50 0.4291 0.64 |Q | | | V |
592 4+51 0.4300 0.63 |Q | | | V |
593 4+52 0.4309 0.62 |Q | | | V |
594 4+53 0.4317 0.62 |Q | | | V |
595 4+54 0.4326 0.61 |Q | | | V |
596 4+55 0.4334 0.60 |Q | | | V |
597 4+56 0.4342 0.59 |Q | | | V |
598 4+57 0.4350 0.59 |Q | | | V |
599 4+58 0.4358 0.58 |Q | | | V |
600 4+59 0.4366 0.57 |Q | | | V |
601 5+ 0 0.4374 0.57 |Q | | | V |
602 5+ 1 0.4382 0.56 |Q | | | V |
603 5+ 2 0.4389 0.55 |Q | | | V |
604 5+ 3 0.4397 0.55 |Q | | | V |
605 5+ 4 0.4404 0.54 |Q | | | V |
606 5+ 5 0.4412 0.54 |Q | | | V |
607 5+ 6 0.4419 0.53 |Q | | | V |
608 5+ 7 0.4426 0.53 |Q | | | V |
609 5+ 8 0.4433 0.52 |Q | | | V |
610 5+ 9 0.4440 0.52 |Q | | | V |
611 5+10 0.4447 0.51 |Q | | | V |
612 5+11 0.4454 0.51 |Q | | | V |
613 5+12 0.4461 0.50 |Q | | | V |
614 5+13 0.4468 0.50 |Q | | | V |
615 5+14 0.4475 0.49 |Q | | | V |
616 5+15 0.4482 0.49 |Q | | | V |
617 5+16 0.4488 0.48 |Q | | | V |
618 5+17 0.4495 0.48 |Q | | | V |
619 5+18 0.4501 0.47 |Q | | | V |
620 5+19 0.4508 0.47 |Q | | | V |
621 5+20 0.4514 0.47 |Q | | | V |
622 5+21 0.4521 0.46 |Q | | | V |
623 5+22 0.4527 0.46 |Q | | | V |
624 5+23 0.4533 0.45 |Q | | | V |
625 5+24 0.4539 0.45 |Q | | | V |
626 5+25 0.4546 0.45 |Q | | | V |
627 5+26 0.4552 0.44 |Q | | | V |
628 5+27 0.4558 0.44 |Q | | | V |
629 5+28 0.4564 0.44 |Q | | | V |
630 5+29 0.4570 0.43 |Q | | | V |
631 5+30 0.4576 0.43 |Q | | | V |
632 5+31 0.4582 0.43 |Q | | | V |
633 5+32 0.4587 0.42 |Q | | | V |
634 5+33 0.4593 0.42 |Q | | | V |
635 5+34 0.4599 0.42 |Q | | | V |
636 5+35 0.4605 0.42 |Q | | | V |
637 5+36 0.4610 0.41 |Q | | | V |
638 5+37 0.4616 0.41 |Q | | | V |
639 5+38 0.4622 0.41 |Q | | | V |
640 5+39 0.4627 0.40 |Q | | | V |
641 5+40 0.4633 0.40 |Q | | | V |
642 5+41 0.4638 0.40 |Q | | | V|
643 5+42 0.4644 0.40 |Q | | | V|
644 5+43 0.4649 0.39 |Q | | | V|
645 5+44 0.4655 0.39 |Q | | | V|
646 5+45 0.4660 0.39 |Q | | | V|
647 5+46 0.4665 0.39 Q | | | V|
648 5+47 0.4671 0.38 Q | | | V|
649 5+48 0.4676 0.38 Q | | | V|
650 5+49 0.4681 0.38 Q | | | V|
651 5+50 0.4686 0.38 Q | | | V|
652 5+51 0.4691 0.37 Q | | | V|
653 5+52 0.4696 0.37 Q | | | V|
654 5+53 0.4702 0.37 Q | | | V|
655 5+54 0.4707 0.37 Q | | | V|
656 5+55 0.4712 0.37 Q | | | V|
657 5+56 0.4717 0.36 Q | | | V|
658 5+57 0.4722 0.36 Q | | | V|
659 5+58 0.4727 0.36 Q | | | V|
660 5+59 0.4732 0.36 Q | | | V|
661 6+ 0 0.4736 0.36 Q | | | V|
662 6+ 1 0.4741 0.35 Q | | | V|
663 6+ 2 0.4746 0.35 Q | | | V|
664 6+ 3 0.4751 0.35 Q | | | V|
665 6+ 4 0.4756 0.35 Q | | | V
666 ----------------------------------------------------------------------- 667
668
669
670
671 End of computations , total study area = 2.192 (Ac .) 672
673
674
1 2 San Diego County Rational Hydrology Program
3 4 CIVILCADD /CIVILDESIGN Engineering Software ,( c)1991 -2019 Version 9.1 5 6 Rational method hydrology program based on
7 San Diego County Flood Control Division 2003 hydrology manual 8 Rational Hydrology Study Date : 04 /06 /23
9 ------------------------------------------------------------------------ 10 22060 POST POC2
11 12
13 14 ------------------------------------------------------------------------ 15 ********* Hydrology Study Control Information ********** 16 17 ------------------------------------------------------------------------ 18 19
20 Program License Serial Number 6332
21 22 ------------------------------------------------------------------------ 23 Rational hydrology study storm event year is 100.0 24 English (in -lb ) input data Units used
25 26 Map data precipitation entered :
27 6 hour , precipitation (inches ) = 3.400
28 24 hour precipitation (inches ) = 5.700
29 P6 /P24 = 59.6%
30 San Diego hydrology manual 'C' values used
31 32
33 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 34 Process from Point /Station 401.000 to Point /Station 402.000 35 **** INITIAL AREA EVALUATION ****
36 ______________________________________________________________________ 37 Decimal fraction soil group A = 0.000
38 Decimal fraction soil group B = 0.000
39 Decimal fraction soil group C = 1.000
40 Decimal fraction soil group D = 0.000
41 [HIGH DENSITY RESIDENTIAL ]
42 (43.0 DU /A or Less )
43 Impervious value , Ai = 0.800
44 Sub -Area C Value = 0.780
45 Initial subarea total flow distance = 100.000 (Ft .) 46 Highest elevation = 601.000 (Ft .)
47 Lowest elevation = 598.000 (Ft .)
48 Elevation difference = 3.000 (Ft .) Slope = 3.000 % 49 INITIAL AREA TIME OF CONCENTRATION CALCULATIONS :
50 The maximum overland flow distance is 85.00 (Ft )
51 for the top area slope value of 3.00 %, in a development type of 52 43.0 DU /A or Less
53 In Accordance With Figure 3-3
54 Initial Area Time of Concentration = 3.68 minutes
55 TC = [1 .8*( 1.1 -C)* distance (Ft .) ^.5)/( % slope^ (1/3)] 56 TC = [1 .8*( 1.1 -0.7800 )*( 85.000^.5 )/( 3.000^ (1/3)]= 3.68 57 Calculated TC of 3.682 minutes is less than 5 minutes , 58 resetting TC to 5.0 minutes for rainfall intensity calculations 59 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 60 Effective runoff coefficient used for area (Q=KCIA ) is C = 0.780 61 Subarea runoff = 0.748 (CFS )
62 Total initial stream area = 0.107 (Ac .)
63 64
65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 66 Process from Point /Station 402.000 to Point /Station 403.000 67 **** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
68 ______________________________________________________________________ 69 Estimated mean flow rate at midpoint of channel = 1.852 (CFS ) 70 Depth of flow = 0.592 (Ft .), Average velocity = 6.020 (Ft /s) 71 ******* Irregular Channel Data ***********
72 ----------------------------------------------------------------- 73 Information entered for subchannel number 1 :
74 Point number 'X' coordinate 'Y' coordinate
75 1 0.00 1.00
76 2 28.50 0.85
77 3 30.00 0.00
78 4 30.00 0.50
79 Manning 's 'N' friction factor = 0.015
80 ----------------------------------------------------------------- 81 Sub -Channel flow = 1.852 (CFS )
82 ' ' flow top width = 1.039 (Ft .)
83 ' ' velocity = 6.020 (Ft /s)
84 ' ' area = 0.308 (Sq .Ft )
85 ' ' Froude number = 1.950
86 87 Upstream point elevation = 598.000 (Ft .)
88 Downstream point elevation = 585.990 (Ft .)
89 Flow length = 334.000 (Ft .)
90 Travel time = 0.92 min .
91 Time of concentration = 4.61 min .
92 Depth of flow = 0.592 (Ft .)
93 Average velocity = 6.020 (Ft /s)
94 Total irregular channel flow = 1.852 (CFS )
95 Irregular channel normal depth above invert elev . = 0.592 (Ft .) 96 Average velocity of channel (s) = 6.020 (Ft /s)
97 Adding area flow to channel
98 Calculated TC of 4.607 minutes is less than 5 minutes , 99 resetting TC to 5.0 minutes for rainfall intensity calculations 100 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 101 Decimal fraction soil group A = 0.000
102 Decimal fraction soil group B = 0.000
103 Decimal fraction soil group C = 0.200
104 Decimal fraction soil group D = 0.800
105 [HIGH DENSITY RESIDENTIAL ]
106 (43.0 DU /A or Less )
107 Impervious value , Ai = 0.800
108 Sub -Area C Value = 0.788
109 Rainfall intensity = 8.958 (In /Hr ) for a 100.0 year storm 110 Effective runoff coefficient used for total area
111 (Q=KCIA ) is C = 0.786 CA = 0.332
112 Subarea runoff = 2.231 (CFS ) for 0.316 (Ac .)
113 Total runoff = 2.978 (CFS ) Total area = 0.423 (Ac .) 114 Depth of flow = 0.700 (Ft .), Average velocity = 6.938 (Ft /s) 115 End of computations , total study area = 0.423 (Ac .) 116
117
118
6c. CivilD Mitigated Post-Development Calculations
1 2 San Diego County Rational Hydrology Program
3 4 CIVILCADD /CIVILDESIGN Engineering Software ,( c)1991 -2019 Version 9.1 5 6 Rational method hydrology program based on
7 San Diego County Flood Control Division 2003 hydrology manual 8 Rational Hydrology Study Date : 04 /06 /23
9 ------------------------------------------------------------------------ 10 22060 POST DISCHARGE POINT 1 MITIGATION
11 MIT
12 13
14 ------------------------------------------------------------------------ 15 ********* Hydrology Study Control Information ********** 16 17 ------------------------------------------------------------------------ 18 19
20 Program License Serial Number 6332
21 22 ------------------------------------------------------------------------ 23 Rational hydrology study storm event year is 100.0 24 English (in -lb ) input data Units used
25 26 Map data precipitation entered :
27 6 hour , precipitation (inches ) = 3.400
28 24 hour precipitation (inches ) = 5.700
29 P6 /P24 = 59.6%
30 San Diego hydrology manual 'C' values used
31 32
33 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 34 Process from Point /Station 101.000 to Point /Station 104.000 35 **** USER DEFINED FLOW INFORMATION AT A POINT **** 36 ______________________________________________________________________ 37 User specified 'C' value of 0.062 given for subarea 38 Rainfall intensity (I) = 8.385 (In /Hr ) for a 100.0 year storm 39 User specified values are as follows :
40 TC = 5.54 min . Rain intensity = 8.38 (In /Hr )
41 Total area = 2.190 (Ac .) Total runoff = 1.140 (CFS ) 42 43
44 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 45 Process from Point /Station 104.000 to Point /Station 105.000 46 **** PIPEFLOW TRAVEL TIME (User specified size ) **** 47 ______________________________________________________________________ 48 Upstream point /station elevation = 583.790 (Ft .) 49 Downstream point /station elevation = 583.020 (Ft .) 50 Pipe length = 139.00 (Ft .) Slope = 0.0055 Manning 's N = 0.013 51 No . of pipes = 1 Required pipe flow = 1.140 (CFS ) 52 Given pipe size = 12.00 (In .)
53 Calculated individual pipe flow = 1.140 (CFS )
54 Normal flow depth in pipe = 5.50 (In .)
55 Flow top width inside pipe = 11.96 (In .)
56 Critical Depth = 5.40 (In .)
57 Pipe flow velocity = 3.25 (Ft /s)
58 Travel time through pipe = 0.71 min .
59 Time of concentration (TC ) = 6.25 min .
60 61
62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 63 Process from Point /Station 105.000 to Point /Station 105.000 64 **** CONFLUENCE OF MAIN STREAMS ****
65 ______________________________________________________________________ 66 The following data inside Main Stream is listed :
67 In Main Stream number : 1
68 Stream flow area = 2.190 (Ac .)
69 Runoff from this stream = 1.140 (CFS )
70 Time of concentration = 6.25 min .
71 Rainfall intensity = 7.755 (In /Hr )
72 Program is now starting with Main Stream No . 2
73 74
75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 76 Process from Point /Station 201.000 to Point /Station 202.000 77 **** INITIAL AREA EVALUATION ****
78 ______________________________________________________________________ 79 Decimal fraction soil group A = 0.000
80 Decimal fraction soil group B = 0.000
81 Decimal fraction soil group C = 0.000
82 Decimal fraction soil group D = 1.000
83 [HIGH DENSITY RESIDENTIAL ]
84 (43.0 DU /A or Less )
85 Impervious value , Ai = 0.800
86 Sub -Area C Value = 0.790
87 Initial subarea total flow distance = 144.000 (Ft .) 88 Highest elevation = 594.410 (Ft .)
89 Lowest elevation = 591.500 (Ft .)
90 Elevation difference = 2.910 (Ft .) Slope = 2.021 % 91 Top of Initial Area Slope adjusted by User to 1.674 % 92 INITIAL AREA TIME OF CONCENTRATION CALCULATIONS :
93 The maximum overland flow distance is 75.00 (Ft )
94 for the top area slope value of 1.67 %, in a development type of 95 43.0 DU /A or Less
96 In Accordance With Figure 3-3
97 Initial Area Time of Concentration = 4.07 minutes
98 TC = [1 .8*( 1.1 -C)* distance (Ft .) ^.5)/( % slope^ (1/3)] 99 TC = [1 .8*( 1.1 -0.7900 )*( 75.000^.5 )/( 1.674^ (1/3)]= 4.07 100 Calculated TC of 4.070 minutes is less than 5 minutes , 101 resetting TC to 5.0 minutes for rainfall intensity calculations 102 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 103 Effective runoff coefficient used for area (Q=KCIA ) is C = 0.790 104 Subarea runoff = 1.260 (CFS )
105 Total initial stream area = 0.178 (Ac .)
106
107
108 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 109 Process from Point /Station 202.000 to Point /Station 203.000 110 **** PIPEFLOW TRAVEL TIME (User specified size ) **** 111 ______________________________________________________________________ 112 Upstream point /station elevation = 587.600 (Ft .) 113 Downstream point /station elevation = 587.530 (Ft .) 114 Pipe length = 14.00 (Ft .) Slope = 0.0050 Manning 's N = 0.013 115 No . of pipes = 1 Required pipe flow = 1.260 (CFS ) 116 Given pipe size = 12.00 (In .)
117 Calculated individual pipe flow = 1.260 (CFS )
118 Normal flow depth in pipe = 6.00 (In .)
119 Flow top width inside pipe = 12.00 (In .)
120 Critical Depth = 5.69 (In .)
121 Pipe flow velocity = 3.21 (Ft /s)
122 Travel time through pipe = 0.07 min .
123 Time of concentration (TC ) = 4.14 min .
124
125
126 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 127 Process from Point /Station 203.000 to Point /Station 203.000 128 **** CONFLUENCE OF MINOR STREAMS ****
129 ______________________________________________________________________ 130 Along Main Stream number : 2 in normal stream number 1 131 Stream flow area = 0.178 (Ac .)
132 Runoff from this stream = 1.260 (CFS )
133 Time of concentration = 4.14 min .
134 Rainfall intensity = 8.958 (In /Hr )
135
136
137 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 138 Process from Point /Station 301.000 to Point /Station 302.000 139 **** INITIAL AREA EVALUATION ****
140 ______________________________________________________________________ 141 Decimal fraction soil group A = 0.000
142 Decimal fraction soil group B = 0.000
143 Decimal fraction soil group C = 0.000
144 Decimal fraction soil group D = 1.000
145 [HIGH DENSITY RESIDENTIAL ]
146 (43.0 DU /A or Less )
147 Impervious value , Ai = 0.800
148 Sub -Area C Value = 0.790
149 Initial subarea total flow distance = 100.000 (Ft .) 150 Highest elevation = 589.000 (Ft .)
151 Lowest elevation = 587.610 (Ft .)
152 Elevation difference = 1.390 (Ft .) Slope = 1.390 % 153 Top of Initial Area Slope adjusted by User to 1.620 % 154 INITIAL AREA TIME OF CONCENTRATION CALCULATIONS :
155 The maximum overland flow distance is 75.00 (Ft ) 156 for the top area slope value of 1.62 %, in a development type of 157 43.0 DU /A or Less
158 In Accordance With Figure 3-3
159 Initial Area Time of Concentration = 4.11 minutes 160 TC = [1 .8*( 1.1 -C)* distance (Ft .) ^.5)/( % slope^ (1/3)] 161 TC = [1 .8*( 1.1 -0.7900 )*( 75.000^.5 )/( 1.620^ (1/3)]= 4.11 162 Calculated TC of 4.115 minutes is less than 5 minutes , 163 resetting TC to 5.0 minutes for rainfall intensity calculations 164 Rainfall intensity (I) = 8.958 (In /Hr ) for a 100.0 year storm 165 Effective runoff coefficient used for area (Q=KCIA ) is C = 0.790 166 Subarea runoff = 0.701 (CFS )
167 Total initial stream area = 0.099 (Ac .)
168
169
170 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 171 Process from Point /Station 302.000 to Point /Station 203.000 172 **** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
173 ______________________________________________________________________ 174 Depth of flow = 0.244 (Ft .), Average velocity = 1.068 (Ft /s) 175 ******* Irregular Channel Data ***********
176 ----------------------------------------------------------------- 177 Information entered for subchannel number 1 :
178 Point number 'X' coordinate 'Y' coordinate
179 1 0.00 0.50
180 2 0.00 0.00
181 3 1.30 0.11
182 4 19.00 0.50
183 Manning 's 'N' friction factor = 0.015
184 ----------------------------------------------------------------- 185 Sub -Channel flow = 0.701 (CFS )
186 ' ' flow top width = 7.397 (Ft .)
187 ' ' velocity = 1.069 (Ft /s)
188 ' ' area = 0.656 (Sq .Ft )
189 ' ' Froude number = 0.632
190
191 Upstream point elevation = 587.610 (Ft .)
192 Downstream point elevation = 587.570 (Ft .)
193 Flow length = 13.000 (Ft .)
194 Travel time = 0.20 min .
195 Time of concentration = 4.32 min .
196 Depth of flow = 0.244 (Ft .)
197 Average velocity = 1.068 (Ft /s)
198 Total irregular channel flow = 0.701 (CFS )
199 Irregular channel normal depth above invert elev . = 0.244 (Ft .) 200 Average velocity of channel (s) = 1.068 (Ft /s)
201
202
203 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 204 Process from Point /Station 203.000 to Point /Station 203.000 205 **** CONFLUENCE OF MINOR STREAMS ****
206 ______________________________________________________________________ 207 Along Main Stream number : 2 in normal stream number 2 208 Stream flow area = 0.099 (Ac .)
209 Runoff from this stream = 0.701 (CFS )
210 Time of concentration = 4.32 min .
211 Rainfall intensity = 8.958 (In /Hr )
212 Summary of stream data :
213
214 Stream Flow rate TC Rainfall Intensity
215 No . ( CFS ) ( min ) ( In /Hr )
216
217
218 1 1.260 4.14 8.958
219 2 0.701 4.32 8.958
220 Qmax (1) =
221 1.000 * 1.000 * 1.260 ) +
222 1.000 * 0.960 * 0.701 ) + = 1.932
223 Qmax (2) =
224 1.000 * 1.000 * 1.260 ) +
225 1.000 * 1.000 * 0.701 ) + = 1.960
226
227 Total of 2 streams to confluence :
228 Flow rates before confluence point :
229 1.260 0.701
230 Maximum flow rates at confluence using above data :
231 1.932 1.960
232 Area of streams before confluence :
233 0.178 0.099
234 Results of confluence :
235 Total flow rate = 1.960 (CFS )
236 Time of concentration = 4.317 min .
237 Effective stream area after confluence = 0.277 (Ac .) 238
239
240 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 241 Process from Point /Station 203.000 to Point /Station 105.000 242 **** IRREGULAR CHANNEL FLOW TRAVEL TIME ****
243 ______________________________________________________________________ 244 Estimated mean flow rate at midpoint of channel = 2.589 (CFS ) 245 Depth of flow = 0.274 (Ft .), Average velocity = 2.905 (Ft /s) 246 ******* Irregular Channel Data ***********
247 ----------------------------------------------------------------- 248 Information entered for subchannel number 1 :
249 Point number 'X' coordinate 'Y' coordinate
250 1 0.00 0.50
251 2 0.00 0.00
252 3 1.30 0.11
253 4 19.00 0.50
254 Manning 's 'N' friction factor = 0.015
255 ----------------------------------------------------------------- 256 Sub -Channel flow = 2.589 (CFS )
257 ' ' flow top width = 8.724 (Ft .)
258 ' ' velocity = 2.905 (Ft /s)
259 ' ' area = 0.891 (Sq .Ft )
260 ' ' Froude number = 1.602
261
262 Upstream point elevation = 587.570 (Ft .)
263 Downstream point elevation = 583.120 (Ft .)
264 Flow length = 237.000 (Ft .)
265 Travel time = 1.36 min .
266 Time of concentration = 5.68 min .
267 Depth of flow = 0.274 (Ft .)
268 Average velocity = 2.905 (Ft /s)
269 Total irregular channel flow = 2.589 (CFS )
270 Irregular channel normal depth above invert elev . = 0.274 (Ft .) 271 Average velocity of channel (s) = 2.905 (Ft /s)
272 Adding area flow to channel
273 Rainfall intensity (I) = 8.254 (In /Hr ) for a 100.0 year storm 274 Decimal fraction soil group A = 0.000
275 Decimal fraction soil group B = 0.000
276 Decimal fraction soil group C = 0.000
277 Decimal fraction soil group D = 1.000
278 [HIGH DENSITY RESIDENTIAL ]
279 (43.0 DU /A or Less )
280 Impervious value , Ai = 0.800
281 Sub -Area C Value = 0.790
282 Rainfall intensity = 8.254 (In /Hr ) for a 100.0 year storm 283 Effective runoff coefficient used for total area
284 (Q=KCIA ) is C = 0.790 CA = 0.382
285 Subarea runoff = 1.189 (CFS ) for 0.206 (Ac .)
286 Total runoff = 3.149 (CFS ) Total area = 0.483 (Ac .) 287 Depth of flow = 0.289 (Ft .), Average velocity = 3.045 (Ft /s) 288
289
290 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 291 Process from Point /Station 105.000 to Point /Station 105.000 292 **** CONFLUENCE OF MAIN STREAMS ****
293 ______________________________________________________________________ 294 The following data inside Main Stream is listed :
295 In Main Stream number : 2
296 Stream flow area = 0.483 (Ac .)
297 Runoff from this stream = 3.149 (CFS )
298 Time of concentration = 5.68 min .
299 Rainfall intensity = 8.254 (In /Hr )
300 Summary of stream data :
301
302 Stream Flow rate TC Rainfall Intensity
303 No . ( CFS ) ( min ) ( In /Hr )
304
305
306 1 1.140 6.25 7.755
307 2 3.149 5.68 8.254
308 Qmax (1) =
309 1.000 * 1.000 * 1.140 ) +
310 0.940 * 1.000 * 3.149 ) + = 4.099
311 Qmax (2) =
312 1.000 * 0.908 * 1.140 ) +
313 1.000 * 1.000 * 3.149 ) + = 4.184
314
315 Total of 2 main streams to confluence :
316 Flow rates before confluence point :
317 1.140 3.149
318 Maximum flow rates at confluence using above data :
319 4.099 4.184
320 Area of streams before confluence :
321 2.190 0.483
322
323
324 Results of confluence :
325 Total flow rate = 4.184 (CFS )
326 Time of concentration = 5.677 min .
327 Effective stream area after confluence = 2.673 (Ac .) 328 End of computations , total study area = 2.673 (Ac .) 329
330
331
ATTACHMENT 7
HYDROGRAPH
7a. HEC-HMS Simulations Results
00:00 01:00 02:00 03:00 04:00 05:00 06:00
01Jan2000
0 2
4 6
8 10
12 14
16 Source "Source-1" Results for Run "22060POC1"
Run:22060POC1 Element:Source-1 Result:Outflow EXPIRED
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
588.200
588.286
588.371
588.457
588.543
588.629
588.714
588.800
00:00 01:00 02:00 03:00 04:00 05:00 06:00
01Jan2000
0 2
4 6
8 10
12 14
Reservoir "BMP-A" Results for Run "22060POC1"
Run:22060POC1 Element:BMP-A Result:Storage EXPIRED Run:22060POC1 Element:BMP-A Result:Pool Elevation EXPIRED Run:22060POC1 Element:BMP-A Result:Outflow EXPIRED Run:22060POC1 Element:BMP-A Result:Combined Inflow EXPIRED
0.00 0.01
0.02 0.03
0.04 0.05
0.06 0.07
0.08 583.50
584.06
584.62
585.19
585.75
586.31
586.88
587.44
588.00
00:00 01:00 02:00 03:00 04:00 05:00 06:00
01Jan2000
0 2
4 6
8 10
12 14
Reservoir "Detention pipe 1" Results for Run "22060 POC1" Run:22060POC1 Element:Detention pipe 1 Result:Storage EXPIRED Run:22060POC1 Element:Detention pipe 1 Result:Pool Elevation EXPIRED Run:22060POC1 Element:Detention pipe 1 Result:Outflow EXPIRED Run:22060POC1 Element:Detention pipe 1 Result:Combined Inflow EXPIRED
7b. Runoff Coefficient C After Detention Structure
CALCULATION AFTER THE DETENTION STRUCTURE
The purpose of the detention structure is to alter the peak flow and or time to peak of a given storm so it will not have a negative impact on the downstream facilities. There are different methods on how to use the resulting values of the outflow hydrograph.
For the purposes of this example there will be an association of the following values:
Q
in = Is equal to the inflow value that will enter the basin before storage Qout = Is equal to the outflow value that will exit the basin after storage Tc in = Is equal to the Time of Concentration flowing into the basin before detention Tc out = Is equal to the Time of Concentration exiting the basin after detention A = Area of the tributary area being examined; (This value does not change) cinflow = The runoff coefficient going into the basin for detention cout = The runoff coefficient recalculated taking into account water stored in pond for detention
One method is to keep the value of c(inflow) and solve for the I=intensity & Tc(outflow). In this interpretation, we will get a Tc that will not match the value of the Tc (out of the detention structure)
of the outflow hydrograph that was calculated using the detention pond. The Tc Using this method shows a disruption on the oneness & continuity of the outflow hydrograph & the formula Q=cIA.
The second method; that is the method we are using is to recalculate the c=coefficient based on the fix values of the outflow hydrograph to achieve a cout . This value uses the c inflow from the flow into the detention basin and then is recalculated by the output of the hydrograph software using Q=cIA; translated as c=Q/IA . This method preserves the formula Q=cIA & does not alter the Tc (out of the detention structure) . This method shows that in order to maintain mathematical integrity of the rational equation (Q=CIA), the detention structure alters the runoff coefficient which is the only unknown in the equation. It is noted that the designer feels it is important to hold the value of Tc and the Q values that are calculated from the hydrograph.
The routing of the runoff through the detention structure gives us the Q (out of the detention structure) and T∆ time lag between Q (inflow) & Q (out of the detention structure) .
The known fix values coming out of the detention structure are:
o Q = cfs
o Tc (out of the detention structure) = minutes
o A = acres
o Please note that c=coefficient is not given directly from the resulting hydrograph coming out of the detention pond.
In order to satisfy the rational equation of Q=CIA (see Section 3 of the 2003 San Diego County Hydrology Manual) coming out of the detention structure, we will calculate the only unknown value of the equation which is the outlet runoff coefficient, C (outlet) . By using the Tc (out of the detention structure) we can solve for the intensity, I. With the intensity (I) value calculated, we can solve for the outlet runoff coefficient, C(outlet) .
The following equations are used in
this stage: Q = CIA I =
7.44P 6D-0.645
Where:
Q
(out of the detention structure) = runoff (cfs), known value Tc (inflow) = detention structure inflow time of concentration (D) (minutes)
T∆ = time lag between Q
(inflow) & Q (out of the detention structure)
(minutes) Tc (out of the detention structure) = Tc (inflow) + T∆ (minutes) P6 = 6 hour precipitation (inches), known value.
I = intensity (inches/hour), calculated based on the value of Tc (out of the detention structure) A = tributary area of the detention structure (acres),
known value C(outflow) = runoff coefficient (unitless), value to be solved
CALCULATIONS For Nodes 802 to 802; BMP-802
AT THE
OUTFLOW OF
NODE 802
LINE ITEM REMARKS
1 P6 inch 3.4 KNOWN VALUE
2 TC (inflow) mins 4.54 KNOWN VALUE
3 TC (lag) mins 1 FROM THE OUTFLOW HYDROGRAPH
4 TC (ouflow) mins 5.54 LINE 2+3
5 I inches/hour 8.385 FROM THE INTENSITY FORMULA
6 Q(outflow) 1.14 KNOWN VALUE
7 A (inflow=outflow) 2.19 KNOWN VALUE
8 c(inflow) 0.79 KNOWN VALUE FROM THE CONTRIBUTING
BASIN(S)
9 c(outflow) 0.062 CALCULATED FROM C=Q/IA
The preceding highlighted data are then used to continue the calculations downstream of the detention structure.
In summary these are the steps of the calculations presented here:
1. Hydrologic methods of calculation as laid out in the 2003 San Diego Hydrology Manual was used upstream of the detention structure. These includes the methods of determining c, Tc and confluence of a junction. The c values used in the proposed conditions range from “undisturbed natural terrain” to “low & high density residential” whichever is appropriate for the contributing basin.
2. At the outflow of the detention structure, the c value was recalculated using the resulting values of the outflow hydrograph. This method preserves the values of Tc (out of the detention structure) , A & Q (outflow) . Methods and software satisfy the formula Q=cIA & the 2003 San Diego Hydrology Manual. This step shows that in order to maintain mathematical integrity of the rational equation (Q=CIA), the detention structure alters the runoff coefficient which is the only unknown in the equation.
3. The values determined in step 2 were used in the continuation of the calculations using the Hydrologic methods of calculation as laid out in the 2003 San Diego Hydrology Manual downstream of the detention structure. These includes the methods of determining c, Tc and confluence of a junction. The c values used in the proposed conditions range from “undisturbed natural terrain” to “low & high density residential” whichever is appropriate for the contributing basin.