HomeMy WebLinkAboutCDP 08-13; Green Dragon Colonial Village; Drainage Study; 2010-03-15DRAINAGE STUDY
FOR
GREEN DRAGON COLONIAL VILLAGE
S.D.P. 08-03
C.U.P. 08-08
C.D.P. 08-13
Prepared: August 17, 2009
Updated: October 29, 2009
Updated: December 15, 2009
JN: 081240-5
Prepared by:
O'Day Consultants, Inc.
2710 Loker Avenue West, Suite 100
Carlsbad, CA 92010-6609
Tel: (760)-931-7770
Fax: (760)-931-8680
George 32014
12/31/10
Date
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 this project as defined in section 6703 of the Business and Professions
Code, and that the design is consistent with current standards.
I understand that the check of project drawings and specifications by the City of Carlsbad is
confined to a review only and does not relieve me, as the Engineer of Work, of my
responsibilities for the project design.
O'Day Consultants, Inc.
2710 Loker Avenue West, Suite 100
Carlsbad, CA 92010
(760)931-7700
* A j*\
Date: J??<**^^ /&. &Q/O
George O'$ay fi
R.C.E. No. 32014 Exp. 12/31/10
GREEN DRAGON COLONIAL VILLAGE
DRAINAGE STUDY
TABLE OF CONTENTS
DECLARATION OF RESPONSIBLE CHARGE 1
1.0 INTRODUCTION 2
1.1 PURPOSE OF STUDY 2
1.2 SITE CHARACTERISTICS 2
1.2.1 Existing Conditions 2
1.2.2 Proposed Conditions 2
1.3 SOIL CLASSIFICATION 3
1.4 SITE VICINITY MAP 3
2.0 RATIONAL METHOD DESCRIPTION 4
3.0 RUNOFF CALCULATIONS 4
3.1 EXISTING CONDITION 4
3.2 PROPOSED CONDITION 5
3.3 EXISTING AND PROPOSED RUNOFF COMPARISON 5
4.0 CONCLUSION 6
5.0 REFERENCES 7
APPENDICES:
APPENDIX A - CALCULATIONS / EXHIBITS
• EXISTING CONDITION RUNOFF CALCULATIONS
• PROPOSED CONDITION HYDROLOGY CALCULATIONS
• EXISTING CONDITION HYDROLOGY MAP
• PROPOSED CONDITION HYDROLOGY MAP
• PROPOSED BMP EXHIBIT
APPENDIX B - HYDROLOGY CHARTS
• HYDROLOGIC SOILS GROUPS
• SAN DIEGO COUNTY 85th PERCENTILEISOPLUVIALS
• RAINFALL ISOPLUVIALS
• INTENSITY DURATION DESIGN CHARTS
• NOMOGRAPH FOR DETERMINATION OF TIME OF
CONCENTRATION, FIGURE 3-3
• NOMOGRAPH FOR DETERMINATION OF TIME OF
CONCENTRATION, FIGURE 3-4
• RUNOFF COEFFICIENTS FOR URBAN AREAS
GREEN DRAGON COLONIAL VILLAGE
DRAINAGE STUDY
1.0 INTRODUCTION
1.1 PURPOSE OF STUDY
The purpose of this preliminary hydrology study is two-fold:
1) determine the potential hydrologic impacts of the proposed development;
2) verify the capacities of the existing drainage facilities to ensure
accommodation of the proposed drainage conditions.
This report compares the proposed development hydrology condition with the
existing hydrology condition using the Rational Method as outlined in the County
of San Diego Hydrology Manual, June 2003 (SD County 2003). This report
analyzes 100-year six-hour storm event flows for the existing and proposed site
conditions. The calculated Q values are used to determine the capacity of existing
and proposed drainage structures in accordance with the City of Carlsbad
Engineering Standards, 2004 to determine adequacy to accommodate run-off.
1.2 SITE CHARACTERISTICS
1.2.1 Existing Conditions
The 3.08 acre site currently consists of a food market building with a footprint of
approximately 18,400 square-feet (0.42 acres) and on-grade parking lot. The site
consists on two distinct drainage basins, Basin 'A' and Basin 'B'. Runoff
generated in Basin 'A' is conveyed via overland flow across the existing parking
lot to a concrete ditch located at the northwest corner of the site. The concrete
ditch then conveys the runoff off site to an existing catch basin located in the
right-of-way of Interstate 5. Runoff generated in Basin 'B' is conveyed via
overland flow to the southeast corner onto Paseo Del Norte through two existing
driveways. See Appendix A for the Existing Condition Hydrology Map.
1.2.2 Proposed Conditions
The proposed project will remodel the existing building and parking lot. Existing
drainage patterns will remain relatively the same. Runoff from both Basin 'A' and
Basin 'B' will be directed into vegetated swales/bioretention basins for storm
water treatment before leaving the site. Runoff from Basin 'A' will enter the
right-of-way of Interstate 5 through a concrete ditch as in the existing condition.
Subdrains located in bioretention basins in Basin 'A' will collect runoff from the
"first flush" storm event while runoff from larger storm events will flow through
the biorentention areas via overland flow. Runoff from Basin 'B' will enter Paseo
Del Norte through two proposed curb outlet. See Appendix A for the Proposed
Condition Hydrology Map.
GREEN DRAGON COLONIAL VILLAGE
DRAINAGE STUDY
1.3 SOIL CLASSIFICATION
The Soil Hydrologic Group for this preliminary drainage study is Type 'D' soil as
determined by using the County of San Diego Hydrology Manual Soil Hydrologic
Groups Map. A copy of the Soils Hydrologic Groups Map is provided in
Appendix A.
1.4 SITE VICINITY MAP
CITY OF OCCAN5IDE
CITY OF VISTA
CITY OF ENCINITAS
VICINITY MAP
NO SCALE
CITY OFSAN MARCOS
GREEN DRAGON COLONIAL VILLAGE
DRAINAGE STUDY
2.0 RATIONAL METHOD DESCRIPTION
The rational method, as described in the SD County 2003 manual, was used to
generate surface runoff flows, which were then used to size the proposed drainage
facilities and to verify the capacity of the existing drainage facilities.
Rational equation: Q = CIA
Q = peak discharge in cubic feet per second (cfs)
C = runoff coefficient (varies with surface)
I = intensity (varies with time of concentration)
A = Area in acres
The design storm for this project is the 100-year event; the corresponding 6-hour
rainfall amount (Pg) and 24-hour rainfall amount (?24) were found using the
Isopluvial Charts in Appendix B. The Pe and PM values are given in the following
table.
6-hour and 24-hour Rainfall
100-year
P6
2.6
P24
4.5
P6/Pl4(%)
57.8
Runoff coefficients for each area were obtained from Table 3-1, Runoff
Coefficients for Urban Areas, included in Appendix B.
3.0 RUNOFF CALCULATIONS
3.1 EXISTING CONDITION
Based on the topography maps the existing site can be subdivided into two
drainage areas. The existing drainage areas are illustrated on the Existing
Hydrology Map in Appendix A. Corresponding runoff coefficients (C) and
rainfall intensity (I) values were derived using the SD County 2003 manual. The
table of coefficients and rainfall isopluvials are included in Appendix B. These
values were used to calculate the peak flow for the 100-year flow (Q) using the
Rational Method. The drainage areas and corresponding Q values are summarized
below.
GREEN DRAGON COLONIAL VILLAGE
DRAINAGE STUDY
Existing Drainage Condition
Basin No
A
B
Area
1.50 acres
1.58 acres
C
0.82
0.82
Iioo
5.46
in./hr.
6.76
in./hr.
Qioo
6.7 cfs
8.8 cfs
3.2 PROPOSED CONDITION
The proposed hydrology conditions for the project have been designed to preserve
the existing drainage patterns to the maximum extent practicable. The proposed
site drainage conditions are shown in Proposed Hydrology Map in Appendix A.
The proposed drainage areas, and corresponding Q values are summarized below.
Basin No
A
B
Area
1.37 acres
1.60 acres
C
0.82
0.82
Iioo
5.96 in./hr.
6.85 in./hr.
Qioo
6.7 cfs
8.6 cfs
3.3 EXISTING AND PROPOSED RUNOFF COMPARISON
The difference between the existing and proposed hydrology conditions are
shown below.
Condition
QIOO Existing
QIOO Proposed
Difference
A
6.7 cfs
6.7 cfs
Ocfs
B
8.8 cfs
8.6 cfs
-0.2 cfs
GREEN DRAGON COLONIAL VILLAGE
DRAINAGE STUDY
4.0 CONCLUSION
In the proposed condition peak run-off for Basin A will remain the same as
existing. The net decrease in run-off for Basin B is approximately 0.2 cfs. This is
in-part due to the proposed vegetated swales/bioretention areas on site that
effectively increase the time of concentration, reduce overall peak runoff, and
treat storm water runoff prior to leaving the site.
GREEN DRAGON COLONIAL VILLAGE
DRAINAGE STUDY
5.0 REFERENCES
City of Carlsbad, Engineering Standards, 2004.
San Diego County Hydrology Manual, County of San Diego Department of Public Works
Flood Control Section, 2003.
GREEN DRAGON COLONIAL VILLAGE
DRAINAGE STUDY
APPENDIX A - CALCULATIONS / EXHIBITS
• EXISTING CONDITION RUNOFF CALCULATIONS
• PROPOSED CONDITION HYDROLOGY CALCULATIONS
• EXISTING CONDITION HYDROLOGY MAP
• PROPOSED CONDITION HYDROLOGY MAP
• PROPOSED BMP EXHIBIT
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Channel Report
Hydraflow Express Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc.
NODE 301 TO 302
Gutter
Cross SI, Sx (ft/ft)
Cross SI, Sw (ft/ft)
Gutter Width (ft)
Invert Elev (ft)
Slope (%)
N-Value
Calculations
Compute by:
Known Q (cfs)
0.02
0.02
1.50
1.00
1.00
0.013
Known Q
= 0.50
Wednesday, Nov 5 2008
Highlighted
Depth (ft) =0.12
Q (cfs) = 0.500
Area (sqft) = 0.36
Velocity (ft/s) = 1.39
Wetted Perim (ft) =6.12
Grit Depth, Yc (ft) =0.12
Spread Width (ft) = 6.00
EGL(ft) =0.15
Elev (ft)
2.00 -
Section
1.75
1.50
1.25
1.00
0.75
Depth (ft)
- 1.00
0.75
0.50
0.25
0.00
-0.25
10 15 20 25 30 35
Reach (ft)
Channel Report
Hydraflow Express Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc.
NODE 302 TO 303
Gutter
Cross SI, Sx (ft/ft)
Cross SI, Sw (ft/ft)
Gutter Width (ft)
Invert Elev (ft)
Slope (%)
N-Value
Calculations
Compute by:
Known Q (cfs)
0.02
0.02
1.50
1.00
6.70
0.013
Known Q
= 0.90
Wednesday, Nov 5 2008
Highlighted
Depth (ft) =0.10
Q (cfs) = 0.900
Area(sqft) = 0.25
Velocity (ft/s) = 3.60
Wetted Perim (ft) =5.10
Grit Depth, Yc (ft) =0.16
Spread Width (ft) = 5.00
EGL(ft) = 0.30
Elev (ft)Section
2.00
1.75
1.50
1.25
1.00
0.75
Depth (ft)
- 1.00
0.75
0.50
0.25
0.00
-0.25
10 15 20 25 30 35
Reach (ft)
Channel Report
Hydraflow Express Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc.
NODE 303 TO 304
Gutter
Cross SI, Sx (ft/ft)
Cross SI, Sw (ft/ft)
Gutter Width (ft)
Invert Elev (ft)
Slope (%)
N-Value
Calculations
Compute by:
Known Q (cfs)
0.02
0.02
1.50
1.00
1.10
0.013
Known Q
= 2.00
Wednesday, Nov 5 2008
Highlighted
Depth (ft) =0.19
Q (cfs) = 2.000
Area (sqft) = 0.90
Velocity (ft/s) = 2.22
Wetted Perim (ft) = 9.69
Grit Depth, Yc (ft) = 0.21
Spread Width (ft) = 9.50
EGL(ft) = 0.27
Elev (ft)
2.00 -
Section
1.75
1.50
1.25
1.00
0.75
Depth (ft)
- 1.00
0.75
0.50
0.25
0.00
-0.25
0 10 15 20 25 30 35
Reach (ft)
Channel Report
Hydraflow Express Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc.
NODE 304 TO 305
Gutter
Cross SI, Sx (ft/ft)
Cross SI, Sw (ft/ft)
Gutter Width (ft)
Invert Elev (ft)
Slope (%)
N-Value
Calculations
Compute by:
Known Q (cfs)
0.02
0.02
1.50
1.00
3.30
0.013
Known Q
= 2.60
Wednesday, Nov 5 2008
Highlighted
Depth (ft) =0.17
Q (cfs) = 2.600
Area(sqft) = 0.72
Velocity (ft/s) = 3.60
Wetted Perim (ft) = 8.67
Grit Depth, Yc (ft) = 0.24
Spread Width (ft) = 8.50
EGL (ft) = 0.37
Elev (ft)
2.00 -
Section
1.75
1.50
1.25
1.00
0.75
Depth (ft)
- 1.00
0.75
0.50
0.25
0.00
-0.25
10 15 20 25 30 35
Reach (ft)
:*********i
O'Day Consultants, Inc.
2710 Loker Avenue West, Suite 100
Carlsbad, CA 92008
Tel: 760-931-7700 Fax: 760-931-8680
******
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w.s. ( 0.56')
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Triangular Channel
Flowrate
Velocity
Depth of Flow
Critical Depth
Freeboard
Total Depth
Width at Water Surface
Top Width
Slope of Channel
Left Side Slope
Right Side Slope
X-Sectional Area
Wetted Perimeter
ARA(2/3)
Mannings 'n'
2.000
2.143
0.558
0.488
0.000
0.558
3.348
3.348
1.500
3.000
3 .000
0.934
3.529
0.385
CFS
fps
feet
feet
feet
feet
feet
feet
%
: 1
: 1
sq. ft
feet
0.035
Channel Report
Hydraflow Express Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc.
CONCRETE SPILLWAY
Tuesday, Sep 23 2008
Rectangular
Bottom Width (ft)
Total Depth (ft)
Invert Elev (ft)
Slope (%)
N-Value
Calculations
Compute by:
Known Q (cfs)
= 3.00
= 0.50
= 1.00
= 1.00
= 0.015
Known Q
= 6.70
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Wetted Perim (ft)
Grit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
0.46
6.700
1.38
4.86
3.92
0.50
3.00
0.83
Elev (ft) Sectjon Depth (ft)
2 nn •• nn.uu
1 7^.I ./ O
1 p;n
1 O^1 .^.O
n 7K. —
*s
•MM
•M
?
mm*
HK
O yc
O cn
O oc
— .n ?c;
.5 1.5 2.5 3.5
Reach (ft)
Channel Report
Hydraflow Express Extension for AutoCAD® Civil 3D® 2008 by Autodesk, Inc.
CONCRETE DITCH SECTION G-G
Trapezoidal
Bottom Width (ft) = 3.00
Side Slopes (z:1) =2.00,2.00
Total Depth (ft) = 0.50
Invert Elev (ft) = 1.00
Slope (%) = 1.00
N-Value = 0.016
Calculations
Compute by:
Known Q (cfs)
Known Q
= 6.70
Monday, Nov 24 2008
Highlighted
Depth (ft)
Q (cfs)
Area (sqft)
Velocity (ft/s)
Wetted Perim (ft)
Grit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
= 0.41
= 6.700
= 1.57
= 4.28
= 4.83
= 0.48
= 4.64
= 0.69
Elev (ft)
2.00 -
1.75
1.50
1.25
1.00
0.75
Section Depth (ft)
- 1.00
0.75
0.50
0.25
0.00
-0.25
Reach (ft)
'**"***" San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software, (c)1991-2006 Version 7.7
Rational method hydrology program based on
San Diego County Flood Control Division 2003 hydrology manual
Rational Hydrology Study Date: 11/18/09
Green Dragon Colonial Village - Proposed Condition Basin B
JN 081240-5
File: G:\081240\Hydrology\0840PRB01.out.doc
*********Hydrology Study Control Information **********
Program License Serial Number 6218
Rational hydrology study storm event year is 100.0
English (in-lb) input data Units used
Map data precipitation entered:
6 hour, precipitation(inches) = 2.600
24 hour precipitation(inches) = 4.500
P6/P24 = 57.8%
San Diego hydrology manual 'C' values used
Process from Point/Station 200.000 to Point/Station 201.000
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Initial subarea total flow distance = 80.000(Ft.)
Highest elevation = 77.100(Ft.)
Lowest elevation = 74.700(Ft.)
Elevation difference = 2.400(Ft.) Slope = 3.000 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 85.00 (Ft)
for the top area slope value of 3.00 %, in a development type of
General Commercial
In Accordance With Figure 3-3
Initial Area Time of Concentration = 3.22 minutes
TC = [1.8*(1.1-C)*distance(Ft.)A.5)/(% slopeA(l/3)]
TC = [1.8* (1.1-0.8200) *( 85.000A.5)/( 3.000^(1/3)]= 3.22
Calculated TC of 3.222 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.820
Subarea runoff = 0.562(CFS)
Total initial stream area = 0.100(Ac.)
Process from Point/Station 201.000 to Point/Station 202.000
**** IMPROVED CHANNEL TRAVEL TIME ****
Upstream point elevation = 74.700(Ft.)
Downstream point elevation = 73.440(Ft.)
Channel length thru subarea = 90.000(Ft.)
Channel base width = 0.000(Ft.)
Slope or 'Z' of left channel bank = 2.000
Slope or 'Z1 of right channel bank = 2.000
Estimated mean flow rate at midpoint of channel = 0.955(CFS)
Manning's 'N' =0.035
Maximum depth of channel = 1.500(Ft.)
Flow(q) thru subarea = 0.955(CFS)
Depth of flow = 0.506(Ft.), Average velocity = 1.865(Ft/s)
Channel flow top width = 2.024 (Ft.)
Flow Velocity = 1.87(Ft/s)
Travel time = 0.80 min.
Time of concentration = 4.03 min.
Critical depth = 0.426(Ft.)
Adding area flow to channel
Calculated TC of 4.026 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storm
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Rainfall intensity = 6.850(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.820 CA = 0.197
Subarea runoff = 0.786(CFS) for 0.140(Ac.)
Total runoff = 1.348(CFS) Total area = 0.240(Ac.)
Depth of flow = 0.576(Ft.), Average velocity = 2.033(Ft/s)
Critical depth = 0.488(Ft.)
Process from Point/Station 202.000 to Point/Station 213.000
**** IMPROVED CHANNEL TRAVEL TIME ****
Upstream point elevation = 73.440(Ft.)
Downstream point elevation = 72.540(Ft.)
Channel length thru subarea = 71.400(Ft.)
Channel base width = 0.000(Ft.)
Slope or 'Z' of left channel bank = 2.000
Slope or 'Z' of right channel bank = 2.000
Estimated mean flow rate at midpoint of channel = 2.556(CFS)
Manning's 'N' =0.035
Maximum depth of channel = 1.500(Ft.)
Flow(q) thru subarea = 2.556(CFS)
Depth of flow = 0.746(Ft.), Average velocity = 2.294(Ft/s)
Channel flow top width = 2.986(Ft.)
Flow Velocity = 2.29(Ft/s)
Travel time = 0.52 min.
Time of concentration = 4.54 min.
Critical depth = 0.633(Ft.)
Adding area flow to channel
Calculated TC of 4.545 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storm
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Rainfall intensity = 6.850(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.820 CA = 0.549
Subarea runoff = 2.415(CFS) for 0.430(Ac.)
Total runoff = 3.764(CFS) Total area = 0.670(Ac.)
Depth of flow = 0.863(Ft.), Average velocity = 2.527(Ft/s)
Critical depth = 0.738(Ft.)
Process from Point/Station 213.000 to Point/Station 214.000
**** IMPROVED CHANNEL TRAVEL TIME ****
Upstream point elevation = 72. 540(Ft.)
Downstream point elevation = 71. 650(Ft.)
Channel length thru subarea = 54.000(Ft.)
Channel base width = 0.000(Ft.)
Slope or 'Z' of left channel bank = 2.000
Slope or 'Z' of right channel bank = 2.000
Estimated mean flow rate at midpoint of channel = 4.241(CFS)
Manning's 'N' = 0.035
Maximum depth of channel = 1.500(Ft.)
Flow(q) thru subarea = 4.241(CFS)
Depth of flow = 0.858(Ft.), Average velocity = 2.879(Ft/s)
Channel flow top width = 3.433(Ft.)
Flow Velocity = 2.88(Ft/s)
Travel time = 0.31 min.
Time of concentration = 4.86 min.
Critical depth = 0.773(Ft.)
Adding area flow to channel
Calculated TC of 4.857 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storm
Decimal fraction soil group A = 0.000
'*«*»»'
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Rainfall intensity = 6.850(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.820 CA = 0.689
Subarea runoff = 0.955(CFS) for 0.170(Ac.)
4.718(CFS) Total area =Total runoff =
Depth of flow =
Critical depth =
0.840(Ac.)
0.893(Ft.), Average velocity =
0.809(Ft.)
2.957(Ft/s)
Process from Point/Station 214.000 to Point/Station
**** IMPROVED CHANNEL TRAVEL TIME ****
203 .000
Upstream point elevation = 71.650(Ft.)
Downstream point elevation = 70.600(Ft.)
Channel length thru subarea = 66.000(Ft.)
Channel base width = 0.000(Ft.)
Slope or 'Z' of left channel bank = 2.000
Slope or 'Z' of right channel bank = 2.000
Estimated mean flow rate at midpoint of channel =
Manning's 'N' =0.035
Maximum depth of channel = 1.500(Ft.)
Flow(q) thru subarea = 5.045(CFS)
Depth of flow = 0.922(Ft.), Average velocity =
Channel flow top width = 3.688(Ft.)
Flow Velocity = 2.97(Ft/s)
Travel time = 0.37 min.
Time of concentration = 5.23 min.
Critical depth = 0.828(Ft.)
Adding area flow to channel
Rainfall intensity (I) = 6.656(In/Hr) for a
Decimal fraction soil group A = 0.000
5.045(CFS)
2.967(Ft/s)
100.0 year storm
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Rainfall intensity = 6.656(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.820 CA = 0.795
0.576(CFS) for 0.130(Ac.)
5.294(CFS) Total area =
Subarea runoff =
Total runoff =
Depth of flow =
Critical depth =
0.939(Ft.), Average velocity =
0.844(Ft.)
0.970(Ac.;
3.003(Ft/s)
Process from Point/Station 203.000 to Point/Station 204.000
**** piPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation =
Downstream point/station elevation =
Pipe length = 61.49 (Ft.) Slope =
No. of pipes = 1 Required pipe flow
Nearest computed pipe diameter
Calculated individual pipe flow =
Normal flow depth in pipe = 12.00(In.)
Flow top width inside pipe = 12.00(In.)
Critical Depth = 11.19(In.)
Pipe flow velocity = 5.03(Ft/s)
Travel time through pipe = 0.20 min.
Time of concentration (TC) = 5.43 min.
67.310(Ft.)
67.000(Ft.)
0.0050 Manning's N = 0.011
5.294(CFS)
15.00(In.)
5.294(CFS)
Process from Point/Station 203.000 to Point/Station
**** CONFLUENCE OF MAIN STREAMS ****
204.000
The following data inside Main Stream is listed:
In Main Stream number: 1
Stream flow area = 0.970(Ac.)
Runoff from this stream = 5.294 (CFS)
Time of concentration = 5.43 min.
Rainfall intensity = 6.494(In/Hr)
Program is now starting with Main Stream No. 2
Process from Point/Station 205.000 to Point/Station
**** INITIAL AREA EVALUATION ****
206.000
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Initial subarea total flow distance = 20.000(Ft.)
Highest elevation = 75.600(Ft.)
Lowest elevation = 74.150(Ft.)
Elevation difference = 1.450(Ft.) Slope = 7.250 %
INITIAL AREA TIME OF CONCENTRATION CALCULATIONS:
The maximum overland flow distance is 90.00 (Ft)
for the top area slope value of 7.25 %, in a development type of
General Commercial
In Accordance With Figure 3-3
Initial Area Time of Concentration = 2.47 minutes
TC = [1.8*(1.1-C)*distance(Ft.)A.5)/(% slope*(1/3)]
TC = [1.8*(1.1-0.8200)*( 90.000A.5)/( 7.250^(1/3)]= 2.47
Calculated TC of 2.470 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.820
Subarea runoff = 0.056(CFS)
Total initial stream area = 0.010(Ac.
Process from Point/Station 206.000 to Point/Station 207.000
**** piPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 71.150(Ft.)
Downstream point/station elevation = 70.800(Ft.)
Pipe length = 26.76(Ft.) Slope = 0.0131 Manning's N = 0.011
No. of pipes = 1 Required pipe flow = 0.056(CFS)
Given pipe size = 6.00(In.)
Calculated individual pipe flow = 0.056(CFS)
Normal flow depth in pipe = 1.11(In.)
Flow top width inside pipe = 4.65(In.)
Critical Depth = 1.39(In.)
Pipe flow velocity = 2.26(Ft/s)
Travel time through pipe = 0.20 min.
Time of concentration (TC) = 2.67 min.
Process from Point/Station 206.000 to Point/Station 207.000
**** SUBAREA FLOW ADDITION ****
Calculated TC of 2.668 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storm
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Time of concentration = 2.67 min.
Rainfall intensity = 6.850(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.820 CA = 0.197
Subarea runoff = 1.292(CFS) for 0.230(Ac.)
Total runoff = 1.348(CFS) Total area = 0.240(Ac.)
Process from Point/Station 207.000 to Point/Station 208.000
**** PIPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation = 70.800(Ft.)
Downstream point/station elevation = 69. 500(Ft.)
Pipe length = 66.92(Ft.) Slope = 0.0194 Manning's N = 0.011
No. of pipes = 1 Required pipe flow = 1.348(CFS)
Nearest computed pipe diameter = 9.00(In.)
Calculated individual pipe flow = 1.348(CFS)
Normal flow depth in pipe = 4.47(In.)
Flow top width inside pipe = 9.00(In.)
Critical Depth = 6.42(In.)
Pipe flow velocity = 6.15(Ft/s)
Travel time through pipe = 0.18 min.
Time of concentration (TC) = 2.85 min.
Process from Point/Station 207.000 to Point/Station
**** SUBAREA FLOW ADDITION ****
208 .000
Calculated TC of 2.849 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storm
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Time of concentration = 2.85 min.
Rainfall intensity = 6.850(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.820 CA = 0.246
Subarea runoff = 0.337(CFS) for 0.060(Ac.)
Total runoff = 1.685(CFS) Total area = 0.300(Ac.)
Process from Point/Station 208.000 to Point/Station 209.000
**** PIPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation =
Downstream point/station elevation =
Pipe length = 47.49(Ft.) Slope =
No. of pipes = 1 Required pipe flow
Nearest computed pipe diameter =
Calculated individual pipe flow =
Normal flow depth in pipe = 6.47(In.)
Flow top width inside pipe = 8.09(In.)
Critical Depth = 7.15(In.)
Pipe flow velocity = 4.96(Ft/s)
Travel time through pipe = 0.16 min.
Time of concentration (TC) = 3.01 min.
69.500(Ft.)
69.030(Ft.)
0.0099 Manning's N = 0.011
1.685(CFS)
9.00(In.)
1.685(CFS)
Process from Point/Station 208.000 to Point/Station
**** SUBAREA FLOW ADDITION ****
209.000
'<**«**'
Calculated TC of 3.009 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storm
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
***"' [COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Time of concentration = 3.01 min.
Rainfall intensity = 6.850(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.820 CA = 0.344
Subarea runoff = 0.674(CFS) for 0.120(Ac.)
Total runoff = 2.359(CFS) Total area = 0.420(Ac.)
Process from Point/Station 209.000 to Point/Station 210.000
**** PIPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation = 69.030(Ft.)
Downstream point/station elevation = 67.900(Ft.)
Pipe length = 60.00(Ft.) Slope = 0.0188 Manning's N = 0.011
No. of pipes = 1 Required pipe flow = 2.359(CFS)
Nearest computed pipe diameter = 9.00(In.)
Calculated individual pipe flow = 2.359(CFS)
Normal flow depth in pipe = 6.55(In.)
Flow top width inside pipe = 8.01(In.)
Critical Depth = 8.18(In.)
Pipe flow velocity = 6.85(Ft/s)
Travel time through pipe = 0.15 min.
Time of concentration (TC) = 3.15 min.
Process from Point/Station 209.000 to Point/Station 210.000
**** SUBAREA FLOW ADDITION ****
Calculated TC of 3.154 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storm
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Time of concentration = 3.15 min.
Rainfall intensity = 6.850(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.820 CA = 0.484
Subarea runoff = 0.955(CFS) for 0.170(Ac.)
Total runoff = 3.314(CFS) Total area = 0.590(Ac.)
Process from Point/Station 210.000 to Point/Station 204.000
**** PIPEFLOW TRAVEL TIME (Program estimated size) ****
Upstream point/station elevation =
Downstream point/station elevation =
Pipe length = 46.50(Ft.) Slope =
No. of pipes = 1 Required pipe flow
Nearest computed pipe diameter =
Calculated individual pipe flow = 3.314(CFS)
Normal flow depth in pipe = 6.46(In.)
Flow top width inside pipe = 11.96(In.)
Critical Depth = 9.35(In.)
Pipe flow velocity = 7.69(Ft/s)
Travel time through pipe = 0.10 min.
Time of concentration (TC) = 3.26 min.
67.900(Ft.)
67.000(Ft.)
0.0194 Manning's N = 0.011
3.314(CFS)
12.00(In.)
Process from Point/Station 210.000 to Point/Station
**** SUBAREA FLOW ADDITION ****
204 .000
Calculated TC of 3.255 minutes is less than 5 minutes,
resetting TC to 5.0 minutes for rainfall intensity calculations
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storm
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[COMMERCIAL area type ]
(General Commercial )
Impervious value, Ai = 0.850
Sub-Area C Value = 0.820
Time of concentration = 3.26 min.
Rainfall intensity = 6.850(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for total area
(Q=KCIA) is C = 0.820 CA = 0.517
Subarea runoff = 0.225(CFS) for 0.040(Ac.)
Total runoff = 3.539(CFS) Total area = 0.630(Ac.)
Process from Point/Station 210.000 to Point/Station
**** CONFLUENCE OF MAIN STREAMS ****
204 .000
The following data inside Main Stream is listed:
In Main Stream number: 2
Stream flow area = 0.630(Ac.)
Runoff from this stream = 3.539(CFS)
Time of concentration = 3.26 min.
Rainfall intensity = 6.850(In/Hr)
Summary of stream data:
Stream
No.
Flow rate
(CFS)
TC
(min)
Rainfall Intensity
(In/Hr)
1 5.294 5.43
2 3.539 3.26
Qmax(1) =
6.494
6.850
1.000 * 1.000 * 5.294) +
0.948 * 1.000 * 3.539) += 8.649
Qmax(2) =
1.000 * 0.599 * 5.294) +
1.000 * 1.000 * 3.539) + = 6.712
Total of 2 main streams to confluence:
Flow rates before confluence point:
5.294 3.539
Maximum flow rates at confluence using above data:
8.649 6.712
Area of streams before confluence:
0.970 0.630
Results of confluence:
Total flow rate = 8.649(CFS)
Time of concentration = 5.432 min.
Effective stream area after confluence = 1.600(Ac.)
Process from Point/Station 204.000 to Point/Station 211.000
**** IMPROVED CHANNEL TRAVEL TIME ****
Upstream point elevation = 67.000(Ft.)
Downstream point elevation = 66.700(Ft.)
Channel length thru subarea = 30.000(Ft.)
Channel base width = 2.000(Ft.)
Slope or 'Z' of left channel bank = 2.000
Slope or 'Z' of right channel bank = 2.000
Manning's 'N' =0.035
Maximum depth of channel = 1.000 (Ft.)
Flow(q) thru subarea = 8.649(CFS)
Depth of flow = 0.839(Ft.), Average velocity = 2.803(Ft/s)
Channel flow top width = 5.356(Ft.)
Flow Velocity = 2.80(Ft/s)
Travel time = 0.18 min.
Time of concentration = 5.61 min.
Critical depth = 0.664(Ft.)
End of computations, total study area = 1.600 (Ac.)
10
J2//-2/2 Curb Oof/€-/
*********************************V •••'
O'Day Consultants, Inc.
2710 Loker Avenue West, Suite 100
Carlsbad, CA 92008
Tel: 760-931-7700 Fax: 760-931-8680
t****|t******* * * *
*
*
*
*
|< ( 5.54')
***** *****
* * * *
* *AAAWater Surface ( 0.25')AA** *
* * * *
* * * *
* * * *
******************
******************
Rectangular Open Channel
Flowrate 8.600 CFS
Velocity 6.206 fps
Depth of Flow 0.250 feet
Critical Depth 0.421 feet
Total Depth 0.250 feet
Base Width 5.541 feet
Slope of Channel 2.100 %
X-Sectional Area 1.385 sq. ft.
Wetted Perimeter 6.041 feet
AR*(2/3) 0.519
Mannings 'n' 0.013
, . «riifeBL!feiri.m,!i™-Jf._. -"ii ..i,,,..JJi
\ 'f* ***** *vu
O'Day Consultants, Inc.
2710 Loker Avenue West, Suite 100
Carlsbad, CA 92008
Tel: 760-931-7700 Fax: 760-931-8680
JL i
******************
*
*
*
*
< ( 3.00')
I I
***** *****
* * * *
* **A*Water Surface { 0.25')AAA* *
* * * *
* * * *
* * * *
******************
******************
Rectangular Open Channel
Flowrate 4.449 CFS
Velocity 5.932 fps
Depth of Flow 0.250 feet
Critical Depth 0.409 feet
Total Depth 0.250 feet
Base Width 3.000 feet
Slope of Channel 2.100 %
X-Sectional Area 0.750 sq. ft.
Wetted Perimeter 3.500 feet
ARA(2/3) 0.269
Mannings 'n1 0.013
2.
GREEN DRAGON COLONIAL VILLAGE
DRAINAGE STUDY
APPENDIX B - HYDROLOGY CHARTS
• HYDROLOGIC SOILS GROUPS
• SAN DIEGO COUNTY 85th PERCENTILE ISOPLUVIALS
• RAINFALL ISOPLUVIALS
• INTENSITY DURATION DESIGN CHARTS
• NOMOGRAPH FOR DETERMINATION OF TIME OF
CONCENTRATION, FIGURE 3-3
• NOMOGRAPH FOR DETERMINATION OF TIME OF
CONCENTRATION, FIGURE 3-4
• RUNOFF COEFFICIENTS FOR URBAN AREAS
(. i
County of San Diego
Hydrology Manual
' iHMi-m
2 Year Rainfall Event - 6 Hours
SiRGIS
33'30-
County of San Diego
Hydrology Manual
.'. ^::; \ /.<.vg»^L
\«si£*r
Rainfall Isopluvials
2 Year Rainfall Event - 24 Hours
(sopluvM (inchec)
DPW CIS
'm «?c Hsv;. S*P. 1>HED 4i«*Clt»i;
JlJ TI«MH*»nKMMBWnNOUt|i*MHMnVO>MniVA.BmMUA. MOUWO. mn MW iwnn m iw MUD M
303
(f
County of San Diego
Hydrology Manual
Rainfall Isopluvials
10 Year Rainfall Event - 6 Hours
MV w *•»* »«,U. INOMWAIUT MPT IMIIO la TM MUDMMfUMJTVJHOHIM*l mi AMHnOMd n
Ft1;! K! i County of San Diego
Hydrology Manual
Rainfall Isopluvials
10 Year Rainfall Event - 24 Hours
teopluvM (inches)
DPW ,-*SSaoGIS
MTMQVT MMUMTV V M
, MIT MOT tflfKO T(k 1W
-3 0 3
County of San Diego
Hydrology Manual
Rainfall Isopluvials
100 Year Rainfall Event- 6 Hours
H-H;H 444-!4ii.i-,.,.;-.i.4.J4_i i_/.2L4
County of San Diego
Hydrology Manual
100 Year Rainfall Event - 24 Hours
i-t'-; ! Iifi-; i?-t-rH-i-i -rt-r t
I = Intensity (in/hr)
P6 = 6-How Precipitation (in)
D = Duration (iron)
Directions for Application:
(1 ) From precipitation maps determine 6 hr and 24 hr amounts
far the selected frequency. These maps are Inducted to 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
applfeaple 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.
Application Form:
(a) Selected frequency
0»P6=^i_in.,P;
(c) Adjusted F
fdityg- min.
(e) I • —' in ./hr.
year
* NA in.
Note: This chart replaces the Intensity-Duration-Frequency
curves used since 1965.
FIGURE
Inteiwity-Duration Dacign Chart -Twnpiate 3-1
100
LU111
LUOI
O
LU
CO
8DC.
LU
I
EXAMPLE:
Given: Watercourse Distance (D) = 70 Feet
Slope (s)= 1.3%
Runoff Coefficient (C) = 0.41
Overtand Flow Time (T) = 9.5 Minutes
SOURCE: Airport Drainage, Federal Aviation Administration. 1965
FIGURE
Rational Formula - Overland Time of Flow Nomograph 3-3
A
1
EQUATION
E _ /11.9L3V>385
Feet IC ~ \~A~jfy
—.5000 Tc = Time of concentration (ho ure)
L = Watercourse Distance (mites)
—4QOO ^E ... change in elevation along
effective slope tine (See Rgure 3-5) (feet)
3000 . Tc
_ Hours
2000 4
—
—
1000
-900
-'TOO
-600\
500^
I— .400 N.
u x% i — •
— 300 V6
X
200 X
I Xx LV Miles Feet
X
: X;:
»
-. 0.5 —— 50
— 40
— 30
— 20
— 10
5
^.4000
" X^
— 3000
X
2000 Xx
— 1800 \
— 1600 x
— 1400 X
— 1200
,—.1000
— 900
— 800
— 700
— 600
— 500
— 400
— 300
•
— 200
Minutes
2—240
^^
— 180
•MM
— 120
— 100
— 90
— 80
— ro
60
— 50
— 40
— 30
20
— 18
— 16
— 14
— 12
— 10
—9
—8
— 7
— 6
5
— 4
—3
AE L fc
SOURCE: California Division of Highways (1941) and Kirpich (1940)
FIGURE
Nomograph for Determination of
Time of Concentration (Tc) or Travel Time (Tt) for Natural Watersheds «3*>4
San Diego County Hydrology Manual
Date: June 2003
Section:
Page:
3
6 of 26
Table 3-1
RUNOFF COEFFICIENTS FOR URBAN AREAS
Land
NRCS Elements
Undisturbed Natural Terrain (Natural)
Low Density Residential (LDR)
Low Density Residential (LDR)
Low Density Residential (LDR)
Medium Density Residential (MDR)
Medium Density Residential (MDR)
Medium Density Residential (MDR)
Medium Density Residential (MDR)
High Density Residential (HDR)
High Density Residential (HDR)
Commercial/Industrial (N. Com)
Commercial/Industrial (G. Com)
Commercial/Industrial (O.P. Com)
Commercial/Industrial (Limited I.)
Commercial/Industrial (General I.)
Use
County Elements
Permanent Open Space
Residential, 1.0 DU/A or less
Residential, 2.0 DU/A or less
Residential, 2.9 DU/A or less
Residential, 4.3 DU/A or less
Residential, 7.3 DU/A or less
Residential, 10.9 DU/A or less
Residential, 14.5 DU/A or less
Residential, 24.0 DU/A or less
Residential, 43.0 DU/A or less
Neighborhood Commercial
General Commercial
Office Professional/Commercial
Limited Industrial
General Industrial
Runoff Coefficient "C"
%IMPER.
0*
10
20
25
30
40
45
50
65
80
80
85
90
90
95
A
0.20
0.27
0.34
038
0.41
0.48
0.52
0.55
0.66
0.76
0.76
0.80
0.83
0.83
0.87
Soil Type
B
0.25
0.32
0.38
0.41
0.45
0.51
0.54
0.58
0.67
0.77
0.77
0.80
0.84
0.84
0.87
C
0.30
0.36
0.42
0.45
0.48
0.54
0.57
0.60
0.69
0.78
0.78
0.81
0.84
0.84
0.87
D
0.35
0.41
0.46
0.49
0.52
0.57
0.60
0.63
0.71
0.79
0.79
ML
0.85
0.85
0.87
•The values associated with 0% impervious may be used for direct calculation of the
coefficient, Cp, for the soil type), or for areas that will remain undisturbed in perpetuitv
is located in Cleveland National Forest). '
DU/A - dwelling units per acre
NRCS = National Resources Conservation Service
runoff coefficient as described in Section 3.1.2 (representing the pervious runoff
Justification must be given mat the area will remain natural forever (e.g., the area
3-6