HomeMy WebLinkAboutCT 01-08; NORTHPOINTE WEST; PRELIMINARY DRAINAGE STUDY NORTHPOINTE; 2002-02-12K&S ENGINEERING
Planning Engineering Surveying
PRELIMINARY DRAINAGE STUDY
FOR
NORTHPOINTE WEST
IN
CITY OF CARLSBAD
JN 00-111
February 12, 2002
DATE ^
7801 Mission Center Court. Suite 100 . San Dlego. California 92108 . (619)296-5566 . Fax (619) 296-5564
FILE COPY
TABLE OF CONTENTS
l.SITE DESCRIPTION
2. HYDROLOGY DESIGN MODELS
3. HYDROLOGIC CALCULATIONS APPENDIX A
4. TABLES AND CHARTS APPENDIX B
5. HYDROLOGY MAPS APPENDIX C
1. SITE DESCRIPTION
A. EXISTING CONDITION
THE EXISTING SITE CONSISTS OF LOTS 9 THRU 12 OF MAP NO.
13716. THESE LOTS WERE MASS-GRADED PER CITY OF CARLSBAD
PROJECT NO. 98-07, GRADING PLAN NO. 365-5A.
THE GRADED PADS CURRENTLY DRAIN IN AN INTERIM CONDITION
TO AN EXISTING DESILTING BASIN LOCATED ON THE SOUTHERLY
SIDE OF LOT NO. 12. THESE COMBINED STORM FLOWS ARE
CONVEYED FROM THE DESILTING BASIN BY AN EXISTING 48"
STORM DRAIN TO AN EXISTING CREEK THAT RUNS ALONG THE
WESTERLY SUBDIVISION BOUNDARY.
STORM FLOWS ALSO ENTER THIS BASIN VIA AN UNDERGROUND
STORM DRAIN SYSTEM FROM THE EXISTING NORTHPOINTE
DEVELOPMENT. APROXIMATELY 13.5 ACRES ARE TRIBUTARY TO
THIS STORM DRAIN SYSTEM. THE EXISTING STORM DRAIN
SYSTEM UTILIZES FOSSIL FILTERS AT ALL CATCH BASINS AND
INLETS TO TREAT THE STORM RUNOFF BEFORE ENTERING THE
EXISTING DESILT BASIN.
ALSO, LOTS 9, 10 AND 11 CONTAIN INDIVIDUAL 24" STORM
DRAIN PIPES CONSTRUCTED PER SAID GRADING PLAN NO. 365-
A. THESE INDIVIDUAL STORM DRAINS. DO NOT ACCEPT FLOWS
IN THE INTERIM CONDITION, BUT ARE INTENDED FOR THE USE
BY THE PROPOSED DEVELOPMENT.
B. PROPOSED CONDITION
THE PROPOSED SITE (NORTHPOINTE WEST) CONSISTS OF
INDUSTRIAL BUILDINGS AND THEIR CORRESPONDING PARKING
AREAS. THE PROPOSED DRAINAGE CONSISTS OF A COMBINATION
OF SURFACE FLOW AND A SYSTEM OF INLETS AND UNDERGROUND
PIPES THAT WILL TIE INTO THE FOUR EXISTING STORM DRAIN
PIPES MENTIONED ON THE "EXISTING CONDITION" AND CONVEY
THE PROPOSED FLOWS TO THE EXISTING CREEK. ALL CATCH
BASINS AND INLETS PROPOSED WITH THIS PROJECT WILL HAVE
FOSSIL FILTERS INSTALLED.
ALSO, A SEPARATE REPORT ENTITLED "CONCEPT WATER QUALITY
PLAN" HAS BEEN PREPARED FOR THE PROJECT. THIS REPORT
ADDRESSES THE SAN DIEGO REGIONAL WATER QUALITY BOARD
ORDER 2001.01. BRIEFLY, THE REPORT DEMONSTRATES THAT
THERE WILL BE NO DOWNSTREAM IMPACTS DUE TO DEVELOPMENT
OF THE SITE WITH RESPECT TO WATER QUALITY AND EROSION.
A MAINTENANCE PROGRAM FOR THE BMP'S HAS ALSO BEEN
ADDRESSED IN THE REPORT.
2. HYDROLOGY DESIGN MODELS
A. DESIGN METHODS
THE RATIONAL METHOD IS USED IN THIS HYDROLOGY STUDY; THE RATIONAL
FORMULA IS AS FOLLOWS:
Q = CIA, WHERE : Q= PEAK DISCHARGE IN CUBIC FEET/SECOND *
C = RUNOFF COEFFICIENT (DIMENSIONLESS)
I = RAINFALL INTENSITY IN INCHES/HOUR (PER APPENDIX XI-A)
A = TRIBUTARY DRAINAGE AREA IN ACRES
*1 ACRE INCHES/HOUR = 1.008 CUBIC FEET/SEC
THE NATURAL WATERSHED METHOD IS ALSO USED IN THIS HYDROLOGY STUDY;
THE NATURAL WATERSHED FLOW FORMULA IS AS FOLLOWS:
Tc=1.8 (1.1-C) (L)-'/[SdOO) ]-^^^
L = OVERLAND TRAVEL DISTANCE IN FEET
S = SLOPE IN FT./FT.
Tc= TIME IN MINUTES
B. DESIGN CRITERIA
- FREQUENCY, 100 YEAR STORM.
- LAND USE PER SPECIFIC PLAN AND TENTATIVE MAP.
- RAIN FALL INTENSITY PER COUNTY OF SAN DIEGO 1993 HYDROLOGY
DESIGN MANUAL.
C. REFERENCES
- COUNTY OF SAN DIEGO 1993, HYDROLOGY MANUAL.
- COUNTY OF SAN DIEGO 1992 REGIONAL STANDARD DRAWING.
- HAND BOOK OF HYDRAULICS BY BRATER & KING, SIXTH EDITION.
APPENDIX A
(3. HYDROLOGIC CALCULATIONS)
6.2
EXISTING HYDROLOGY
San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2000 Version
Rational method hydrology program based on
San Diego County Flood Control Division 1985 hydrology manual
Rational Hydrology Study Date: 03/06/01
****-k-k-k-k-k Hydrology Study Control Information ************
K&S Engineering, San Diego, California - S/N 868
Rational hydrology study storm event year is 100.0
English (in-lb) input data Units used
English (in) rainfall data used
Map data precipitation entered:
6 hour, precipitation(inches) = 2.600
24 hour precipitation(inches) = 4.200
Adjusted 6 hour precipitation (inches) = 2.600
P6/P24 = 61.9%
San Diego hydrology manual 'C values used
Runoff coefficients by rational method
-^-1--I--I--^-I--H-I--I-+-H-H-H-I--I--f-f-H-I--I--I--I--f-h-H H--I--f-H-I--H-I--f-f-H-H +-I--I--I--H-I-+
-l-l--I--1-1-
Process from Point/Station 1.000 to Point/Station
2.000
**** INITIAL AREA EVALUATION ****
User specified 'C value of 0.450 given for subarea
Initial subarea flow distance = 365.000(Ft.)
Highest elevation = 276.000(Ft.)
Lowest elevation = 270.000(Ft.)
Elevation difference = 6.000(Ft.)
Time of concentration calculated by the urban
areas overland flow method (App X-C) = 18.94 min.
TC = [1.8*(l.l-C)*distance(Ft.)^.5)/(% slope^(l/3)]
TC = [1.8*(1.1-0.4500)*( 365.000^.5)/( 1.644^(1/3)]= 18.94
Rainfall intensity (I) = 2.902(In/Hr) for a 100.0 year
storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.450
Subarea runoff = 3.055(CFS)
Total initial stream area = 2.340(Ac.)
+++++++^. ^.-H-I-++++-I-+-I--h++-h-I--I--H-f-I--I--f-I--I--f-f-I--1--I--I--H-f-f-f-f-I--f-I-+
-H-f-H-
Process from Point/Station 2.000 to Point/Station
3.000
**** IMPROVED CHANNEL TRAVEL TIME ****
Upstream point elevation = 270.000(Ft.)
Downstream point elevation = 263.500(Ft.)
Channel length thru subarea = 250.000(Ft.)
Channel base width = 1.000(Ft.)
Slope or 'Z' of left channel bank = 2.000
Slope or 'Z' of right channel bank = 2.000
Manning's 'N' = 0.020
Maximum depth of channel = 1.000(Ft.)
Flow(q) thru subarea = 3.055(CFS)
Depth of flow = 0.373(Ft.), Average velocity = 4.683(Ft/s)
Channel flow top width = 2.4 94(Ft.)
Flow Velocity = 4.68(Ft/s)
Travel time = 0.89 min.
Time of concentration = 19.83 min.
Critical depth = 0.484(Ft.)
-f-h-I--H-H-H-I--I--f-f-I--h-H-H-I--I--^-H-H-I--I--f-h-H-I--H-I--I-+-f-H-H-H-I--I-H--I--f-I--I--I-+ + +
-I--I-I--I-1-
Process from Point/Station 2.000 to Point/Station
3.000
**** SUBAREA FLOW ADDITION ****
User specified 'C value of 0.450 given for subarea
Time of concentration = 19.83 min.
Rainfall intensity = 2.817(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area, Rational method,Q=KCIA, C =
0.450
Subarea runoff = 2.662(CFS) for 2.100(Ac.)
Total runoff = 5.717(CFS) Total area = 4.44(Ac.)
+ +-I--I--I--I--I--(--H-H-I--I-+-I--I--H-H-I--I--f-f-H-f-H-I--f-I--H-H-I--h-I--H-I--H-H-H-I--I--f-I--f-h +
-I-I-I--I-I-
Process from Point/Station 3.000 to Point/Station
4.000
**** IMPROVED CHANNEL TRAVEL TIME ****
Upstream point elevation = 263.500(Ft.)
Downstream point elevation = 260.000(Ft.)
Channel length thru subarea = 310.000(Ft.)
Channel base width = 1.000(Ft.)
Slope or 'Z' of left channel bank = 2.000
Slope or 'Z' of right channel bank = 2.000
Manning's 'N' = 0.020
Maximum depth of channel = 1.000(Ft.)
Flow(q) thru subarea = 5.717(CFS)
Depth of flow = 0.624(Ft.), Average velocity = 4.071(Ft/s)
Channel flow top width = 3.4 98(Ft.)
Flow Velocity = 4.07(Ft/s)
Travel time = 1.27 min.
Time of concentration = 21.10 min.
Critical depth = 0.664(Ft.)
-I-+-h-1--I--f +-f-I--f-f-h-H-I--H-f-H-H-I--f-f-h-h-f-I--H-I--I--I--f-f-h-I--I--f-h-I--f-H-I--I--t-+
-I--I--I-I--*-
Process from Point/Station 3.000 to Point/Station
4.000
**** SUBAREA FLOW ADDITION ****
User specified 'C value of 0.450 given for subarea
Time of concentration = 21.10 min.
Rainfall intensity = 2.706(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area. Rational method,Q=KCIA, C =
0.450
Subarea runoff = 3.276(CFS) for 2.690(Ac.)
Total runoff = 8.994(CFS) Total area = 7.13(Ac.)
-I--(--I-+ +-H-I-+-I--H-H-H-f-f-H-H-I--I--f-H-H-f-f-H-H-I--f-f-I--I--I--f ++-H-I-+-f + +-I-++
-I--I--I--I-I-
Process from Point/Station 4.000 to Point/Station
5.000
**** IMPROVED CHANNEL TRAVEL TIME ****
Upstream point elevation = 260.000(Ft.)
Downstream point elevation = 251.000(Ft.)
Channel length thru subarea = 320.000(Ft.)
Channel base width = 45.000(Ft.)
Slope or 'Z' of left channel bank = 2.000
Slope or 'Z' of right channel bank = 2.000
Manning's 'N' = 0.020
Maximum depth of channel = 10.000(Ft.)
Flow(q) thru subarea = 8.994(CFS)
Depth of flow = 0.084(Ft.), Average velocity = 2.378(Ft/s)
Channel flow top width = 4 5.335(Ft.)
Flow Velocity = 2.38(Ft/s)
Travel time = 2.24 min.
Time of concentration = 23.34 min.
Critical depth = 0.107(Ft.)
-I-^..(.-^-I--H-(-+-H-H-H-H + +-I--H-I--^-t--I--I--I--1--f-I--f-H-I--f-H-H-I--f-f-I--f-I--I--I--H+-I--I-+
-l-l--f-I-t-
Process frora Point/Station 4.000 to Point/Station
5.000
**** SUBAREA FLOW ADDITION ****
User specified 'C value of 0.450 given for subarea
Time of concentration = 23.34 min.
Rainfall intensity = 2.536(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area. Rational method,Q=KCIA, C
0.450
Subarea runoff = 3.195(CFS) for 2.800(Ac.)
Total runoff = 12.188(CFS) Total area = 9.93{Ac.)
-f-I--I--I--f-f-f-I--I--H-h-I--^-f-I--H-f-f-I--H-I--I--f-f-^-I--t--I--I--^-^-I--^-I--^-f-f-I--I--I-
•f-i--i--i--i-
Process from Point/Station 4.000 to Point/Station
5.000
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Stream flow area = 9.930(Ac.)
Runoff from this stream = 12.188(CFS)
Time of concentration = 23.34 min.
Rainfall intensity = 2.536(In/Hr)
-I--H-f-1--1--H-I--I--H-f-I--H-t--H-H-H-f-f-f-H-H-I--H-H-H-f-H-^-I--H-I--H-h-I--H-I--I--I--1--I-+
-I--I--H-f-I-
Process from Point/Station 303.000 to Point/Station
6.000
**** USER DEFINED FLOW INFORMATION AT A POINT ****
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
[INDUSTRIAL area type ]
Rainfall intensity (I) = 4.843(In/Hr) for a 100.0 year
storm
User specified values are as follows:
TC = 8.56 min. Rain intensity = 4.84(In/Hr)
Total area = 14.740(Ac.) Total runoff = 72.684(CFS)
-I--1--I--f-f-I--1--I--I--I--H-I--I--I--I--I--I--I--I--I--I--I--I--I--I--H-f-I--h-I--H-H-I--I--I--I--I--I--f-f+
-I-H-H--I-
Process from Point/Station 6.000 to Point/Station
5.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 254.670(Ft.)
Downstream point/station elevation = 252.270(Ft.)
Pipe length = 177.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 72.684(CFS)
Given pipe size = 36.00(In.)
Calculated individual pipe flow = 72.684(CFS)
Normal flow depth in pipe = 27.61(In.)
Flow top width inside pipe = 30.44(In.)
Critical Depth = 32.32(In.)
Pipe flow velocity = 12.4 9(Ft/s)
Travel time through pipe = 0.24 min.
Time of concentration (TC) = 8.80 min.
++-H-I--H-I--I--I--I--H-t--I--H-H-I--I--f-I--f-I--H-I--I--I--f-f-I--H-H-I--I--I--H-I--f-I--I-+-I--I--I-+
-l-l--l-l--I-
Process from Point/Station 6.000 to Point/Station
5.000
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Stream flow area = 14.740(Ac.)
Runoff from this stream = 72.684(CFS)
Time of concentration = 8.80 min.
Rainfall intensity = 4.759(In/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (In/Hr)
1 12.188 23.34 2.536
2 72.684 8.80 4.759
Qmax(1)
Qmax(2)
1.000 * 1.000 * 12.188) -I-
0.533 * 1.000 * 72.684) -H = 50.920
1.000 * 0.377 * 12.188) -i-
1.000 * 1.000 * 72.684) -H = 77.277
Total of 2 streams to confluence:
Flow rates before confluence point:
12.188 72.684
Maximum flow rates at confluence using above data:
50.920 77.277
Area of streams before confluence:
9.930 14.740
Results of confluence:
Total flow rate = 77.277(CFS)
Time of concentration = 8.7 96 min.
Effective stream area after confluence = 24.670(Ac.)
+ + + + + + + + +-H-H-H + +-I--H-(--1--H +-I--I--I--H-H-I--h-H-H-I--I--I--H-I--I-4--I--I--I--I--I--I--f-f
-I--f-f-f-I-
Process from Point/Station 5.000 to Point/Station
7.000
-*r*** PIPEFLOW TRAVEL TIME (User specified size) ****
h-f-f-f-f-f
Upstream point/station elevation = 247.000(Ft.)
Downstream point/station elevation = 246.800(Ft.)
Pipe length = 20.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 77.277(CFS)
Given pipe size = 36.00(In.)
NOTE: Normal flow is pressure flow in user selected pipe size.
The approximate hydraulic grade line above the pipe invert is
2.852(Ft.) at the headworks or inlet of the pipe(s)
Pipe friction loss = 0.268(Ft.)
Minor friction loss = 2.784(Ft.) K-factor = 1.50
Pipe flow velocity = 10.93(Ft/s)
Travel time through pipe = 0.03 min.
Time of concentration (TC) = 8.83 min.
-f +++-h-H-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
-f-f-f-f-f
Process from Point/Station 7.000 to Point/Station
8.000
PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 246.470(Ft.)
Downstream point/station elevation = 221.620(Ft.)
Pipe length = 46.75(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 77.277(CFS)
Given pipe size = 36.00(In.)
Calculated individual pipe flow = 77.277(CFS)
Normal flow depth in pipe = 9.70(In.)
Flow top width inside pipe = 31.95(In.)
Critical Depth = 32.93(In.)
Pipe flow velocity = 50.31(Ft/s)
Travel time through pipe = 0.02 min.
Time of concentration (TC) = 8.84 min.
-I-+-H+-H-H-H-f+-f-f-f-f-f-f-f-f-f-f-f+-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
-f-f-f-f-f
Process from Point/Station 8.000 to Point/Station
9.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 220.620(Ft.)
Downstream point/station elevation = 220.260(Ft.)
Pipe length = 35.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 77.277(CFS)
Given pipe size = 48.00(In.)
Calculated individual pipe flow = 77.277(CFS)
Normal flow depth in pipe = 24.84(In.)
Flow top width inside pipe = 47.97(In.)
Critical Depth = 31.91(In.)
Pipe flow velocity = 11.76(Ft/s)
Travel time through pipe = 0.05 min.
Time of concentration (TC) = 8.89 min.
-I--(--I--^-I--I--I--I--H-I-+-H-H-I--H-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f
-f-f-f-f-f
Process frora Point/Station 8.000 to Point/Station
9.000
**** SUBAREA FLOW ADDITION ****
User specified 'C value of 0.4 50 given for subarea
Time of concentration = 8.89 min.
Rainfall intensity = 4.725(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area, Rational method,Q=KCIA, C =
0.450
Subarea runoff = 2.552(CFS) for 1.200(Ac.)
Total runoff = 79.829(CFS) Total area = 25.87(Ac.)
+ + + + + + + + + + ++-(--!- + -(-++-)-+ -f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-ft
-f-f-f-f-f
Process from Point/Station 9.000 to Point/Station
10.000
PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 220.260(Ft.)
Downstream point/station elevation = 220.200(Ft.)
Pipe length = 35.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 79.829(CFS)
Given pipe size = 48.00(In.)
NOTE: Normal flow is pressure flow in user selected pipe size.
The approximate hydraulic grade line above the pipe invert is
0.988(Ft.) at the headworks or inlet of the pipe(s)
Pipe friction loss = 0.108(Ft.)
Minor friction loss = 0.940(Ft.) K-factor = 1.50
Pipe flow velocity = 6.35(Ft/s)
Travel time through pipe = 0.09 min.
Time of concentration (TC) = 8.98 min.
End of computations, total study area = 25.870 (Ac.)
PROPOSED HYDROLOGY
San Diego County Rational Hydrology Program
CIVILCADD/CIVILDESIGN Engineering Software,(c)1991-2001 Version 6.2
Rational method hydrology prograra based on
San Diego County Flood Control Division 1985 hydrology manual
Rational Hydrology Study Date: 11/27/01
Hydrology Study Control Inforraation
K&S Engineering, San Diego, California - S/N 868
Rational hydrology study storra event year is 100.0
English (in-lb) input data Units used
English (in) rainfall data used
Map data precipitation entered:
6 hour, precipitation(inches) = 2.600
24 hour precipitation(inches) = 4.200
Adjusted 6 hour precipitation (inches) = 2.600
P6/P24 = 61.9%
San Diego hydrology manual 'C values used
Runoff coefficients by rational method
-(--h-h-H-H-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f
Process from Point/Station 1.000 to Point/Station 2.000
**** 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
[INDUSTRIAL area type ]
Initial subarea flow distance = 400.000(Ft.)
Highest elevation = 275.560(Ft.)
Lowest elevation = 270.170(Ft.)
Elevation difference = 5.390(Ft.)
Time of concentration calculated by the urban
areas overland flow method (App X-C) = 4.89 min.
TC = [1.8*{l.l-C)*distance(Ft.)'^.5)/(% slope'^ (1/3) ]
TC = [1.8*(l.l-0.9500)*( 400.000^^.5)/( 1. 347'^ (1/3) ] = 4.89
Setting time of concentration to 5 minutes
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storra
Effective runoff coefficient used for area (Q=KCIA) is C = 0.950
Subarea runoff = 7.159(CFS)
Total initial stream area = 1.100(Ac.)
+ + + + + + + + + + + + + + + -!--!--(--I--^-H-I--^ + -H-H + -|--H-H-H-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f +
Process from Point/Station 1.000 to Point/Station 2.000
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 1
Streara flow area = 1.100(Ac.)
Runoff from this stream = 7.159(CFS)
Time of concentration = 5.00 min.
Rainfall intensity = 6.850(In/Hr)
+++++++++++-I--H-I-^.-H-H-I-.^-I--H-I--t--1--I-++-h+-I-+-1--I--I--f-f-f-f-f-f-f-f-f-f-f-f-f-f+
Process from Point/Station 20.000 to Point/Station 21.000
**** INITIAL AREA EVALUATION ****
Decimal fraction soil group A = 0.000
Deciraal fraction soil group B = 0.000
Deciraal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[INDUSTRIAL area type ]
Initial subarea flow distance = 160.000(Ft.)
Highest elevation = 273.040(Ft.)
Lowest elevation = 269.570(Ft.)
Elevation difference = 3.470(Ft.)
Time of concentration calculated by the urban
areas overland flow method (App X-C) = 2.64 min.
TC = [1.8*(l.l-C)*distance(Ft.)'^.5)/(% slope^(l/3)]
TC = [1.8*(l.l-0.9500)*( 160.000^^.5) / ( 2 .169^^ (1/3) ] = 2.64
Setting time of concentration to 5 minutes
Rainfall intensity (I) = 6.850(In/Hr) for a 100.0 year storra
Effective runoff coefficient used for area {Q=KCIA) is C = 0.950
Subarea runoff = 8.330(CFS)
Total initial stream area = 1.280(Ac.)
+ + + + + H-+-H-H-I--H +-I--1--H-H + + + +-H-H-t--H-H-h-H-I--1--H-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f
Process from Point/Station 21.000 to Point/Station 2.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 266.070(Ft.)
Downstreara point/station elevation = 258.300(Ft.)
Pipe length = 114.50(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 8.330(CFS)
Given pipe size = 12.00(In.)
Calculated individual pipe flow = 8.330(CFS)
Normal flow depth in pipe = 8.88 (In.)
Flow top width inside pipe = 10.52(In.)
Critical depth could not be calculated.
Pipe flow velocity = 13.37(Ft/s)
Travel time through pipe = 0.14 min.
Time of concentration (TC) = 5.14 min.
-f-f-f-f-f-f-f-f+-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-I--I--I--t--1-+-I-+-I-
Process from Point/Station 21.000 to Point/Station 2.000
**** CONFLUENCE OF MINOR STREAMS ****
Along Main Stream number: 1 in normal stream number 2
Streara flow area = 1.280(Ac.)
Runoff from this stream = 8.330(CFS)
Time of concentration = .5.14 rain.
Rainfall intensity = 6.727(In/Hr)
Summary of stream data:
Stream Flow rate TC Rainfall Intensity
No. (CFS) (min) (In/Hr)
1 7.159 5.00 6.850
2 8.330 5.14 6.727
Qmax(1
Qmax(2) =
1.000 * 1.000 * 7.159) -f
1.000 * 0.972 * 8.330) -f = 15.257
0.982 * 1.000 * 7.159) -f
1.000 * 1.000 * 8.330) -f = 15.360
Total of 2 strearas to confluence:
Flow rates before confluence point:
7.159 8.330
Maxiraum flow rates at confluence using above data:
15.257 15.360
Area of streams before confluence:
1.100 1.280
Results of confluence:
Total flow rate = 15.360(CFS)
Time of concentration = 5.143 min.
Effective stream area after confluence = 2.380(Ac.)
-1--I-+-I--1--f-f++-f-f-f-f-f+-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
Process from Point/Station 2.000 to Point/Station 3.000
**** PIPEFLOW TRAVEL TIME (User specified size) **** Upstreara point/station elevation = 258.550(Ft.)
Downstream point/station elevation = 241.200(Ft.)
Pipe length = 60.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 15.360(CFS)
Given pipe size = 24.00(In.)
Calculated individual pipe flow = 15.360(CFS)
Norraal flow depth in pipe = 5.76(In.)
Flow top width inside pipe = 20.50(In.)
Critical Depth = 16.95(In.)
Pipe flow velocity = 26.50(Ft/s)
Travel tirae through pipe = 0.04 min.
Tirae of concentration (TC) = 5.18 rain.
+++++++++++-I--I--I--I--I--I--I-+-I--H-I--H-I--I-+-H-H-1-+-f-f-f-f-f-f-f-f-f-f-f-f-f
Process from Point/Station 1.000 to Point/Station 4.000
* * * •*
INITIAL AREA EVALUATION
Decimal fraction soil group A = 0.000
Decimal fraction soil group B = 0.000
Deciraal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[INDUSTRIAL area type ]
Initial subarea flow distance = 500.000(Ft.)
Highest elevation = 275.560(Ft.)
Lowest elevation = 267.500(Ft.)
Elevation difference = 8.060(Ft.)
Time of concentration calculated by the urban
areas overland flow method (App X-C) = 5.15 min.
TC = [1.8*(l.l-C)*distance(Ft.)''.5)/(% slope^(l/3)]
TC = [1.8*(l.l-0.9500)*( 500.000".5)/( 1. 612^^ (1/3) ] = 5.15
Rainfall intensity (I) = 6.722(In/Hr) for a 100.0 year storra
Effective runoff coefficient used for area (Q=KCIA) is C = 0.950
Subarea runoff = 13.091(CFS)
Total initial stream area = 2.050(Ac.)
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-I--f-I--I-++++
Process frora Point/Station 4.000 to Point/Station 5.000
**** IMPROVED CHANNEL TRAVEL TIME ****
Upstreara point elevation = 267.500(Ft.)
Downstream point elevation = 265.220(Ft.)
Channel length thru subarea = 200.000(Ft.)
Channel base width = 0.000(Ft.)
Slope or 'Z' of left channel bank = 67.000
Slope or 'Z' of right channel bank = 67.000
Estimated mean flow rate at midpoint of channel = 16.156(CFS)
Manning's 'N' = 0.015
Maximum depth of channel = 1.000(Ft.)
Flow(q) thru subarea = 16.156(CFS)
Depth of flow = 0.288(Ft.), Average velocity = 2.906(Ft/s)
Channel flow top width = 38.599(Ft.)
Flow Velocity = 2.91(Ft/s)
Travel time = 1.15 min.
Tirae of concentration = 6.30 rain.
Critical depth = 0.324(Ft.)
Adding area flow to channel
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
[INDUSTRIAL area type ]
Rainfall intensity = 5.904(In/Hr) for a 100.0 year storra
Runoff coefficient used for sub-area. Rational method,Q=KCIA, C = 0.950
Subarea runoff = 5.384(CFS) for 0.960(Ac.)
Total runoff = 18.475(CFS) Total area = 3.01(Ac.)
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
Process from Point/Station 5.000 to Point/Station 6.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 262.050(Ft.)
Downstream point/station elevation = 251.500(Ft.)
Pipe length = 4 6.20(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 18.475(CFS)
Given pipe size = 15.00(In.)
Calculated individual pipe flow = 18.475(CFS)
Normal flow depth in pipe = 8.36(In.)
Flow top width inside pipe = 14.90(In.)
Critical depth could not be calculated.
Pipe flow velocity = 26.28(Ft/s)
Travel time through pipe = 0.03 min.
Time of concentration (TC) = 6.33 min.
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
Process from Point/Station 6.000 to Point/Station 7.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstreara point/station elevation = 251.170(Ft.)
Downstreara point/station elevation = 234.200(Ft.)
Pipe length = 55.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 18.475(CFS)
Given pipe size = 24.00(In.)
Calculated individual pipe flow = 18.475(CFS)
Normal flow depth in pipe = 6.22(In.)
Flow top width inside pipe = 21.03(In.)
Critical Depth = 18.58(In.)
Pipe flow velocity = 28.60(Ft/s)
Travel time through pipe = 0.03 min.
Time of concentration (TC) = 6.36 min.
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-I-+++++-I--I--1^
Process from Point/Station 8.000 to Point/Station 9.000
**** 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
[INDUSTRIAL area type ]
Initial subarea flow distance = 500.000(Ft.)
Highest elevation = 269.500(Ft.)
Lowest elevation = 261.670(Ft.)
Elevation difference = 7.830(Ft.)
Time of concentration calculated by the urban
areas overland flow raethod (App X-C) = 5.20 min.
TC = [1.8*(l.l-C)*distance(Ft.)^.5)/(% slope'^ (1/3) ]
TC = [1.8*(l.l-0.9500)*( 500.000".5)/( 1.566^^(1/3)]= 5.20
Rainfall intensity (I) = 6.680(In/Hr) for a 100.0 year storm
Effective runoff coefficient used for area (Q=KCIA) is C = 0.950
Subarea runoff = 19.927(CFS)
Total initial stream area = 3.140(Ac.)
-f-f-f-f-f-f-f-f-f-f-f +-f-f-H-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f +
Process from Point/Station 9.000 to Point/Station 10.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 258.500(Ft.)
Downstream point/station elevation = 248.000(Ft.)
Pipe length = 78.30(Ft.) Manning's N = 0.015
No. of pipes = 1 Required pipe flow = 19.927(CFS)
Given pipe size = 18.00(In.)
Calculated individual pipe flow = 19.927(CFS)
Norraal flow depth in pipe = 10.03(In.)
Flow top width inside pipe = 17.88(In.)
Critical depth could not be calculated.
Pipe flow velocity = 19.71(Ft/s)
Travel time through pipe = 0.07 min.
Time of concentration (TC) = 5.27 min.
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
Process from Point/Station 10.000 to Point/Station 11.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstreara point/station elevation = 246.950(Ft.)
Downstream point/station elevation = 230.800(Ft.)
Pipe length = 90.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 19.927(CFS)
Given pipe size = 24.00(In.)
Calculated individual pipe flow = 19.927(CFS)
Normal flow depth in pipe = 7.43 (In.)
Flow top width inside pipe = 22.19(In.)
Critical Depth = 19.24(In.)
Pipe flow velocity = 24.08(Ft/s)
Travel time through pipe = 0.06 min.
Time of concentration (TC) = 5.33 min.
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+-f-f-f-f-f-f-f-f-f
Process from Point/Station 12.000 to Point/Station 13.000
**** USER DEFINED FLOW INFORMATION AT A POINT ****
Decimal fraction soil group A = 0.000
Deciraal fraction soil group B = 0.000
Deciraal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[INDUSTRIAL area type ]
Rainfall intensity (I) = 4.844(In/Hr) for a 100.0 year storm
User specified values are as follows:
TC = 8.56 rain. Rain intensity = 4.84(In/Hr)
Total area = 14.740(Ac.) Total runoff = 72.684(CFS)
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f
Process from Point/Station 13.000 to Point/Station 14.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstreara point/station elevation = 254.670(Ft.)
Downstream point/station elevation = 253.840(Ft.)
Pipe length = 85.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 72.684(CFS)
Given pipe size = 36.00(In.)
NOTE: Normal flow is pressure flow in user selected pipe size.
The approximate hydraulic grade line above the pipe invert is
2.642(Ft.) at the headworks or inlet of the pipe(s)
Pipe friction loss = 1.009(Ft.)
Minor friction loss = 2.463(Ft.) K-factor = 1.50
Pipe flow velocity = 10.28(Ft/s)
Travel time through pipe = 0.14 min.
Time of concentration (TC) = 8.69 min.
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
Process frora Point/Station 13.000 to Point/Station 14.000
**** SUBAREA FLOW ADDITION ****
Deciraal fraction soil group A = 0.000
Deciraal fraction soil group B = 0.000
Decimal fraction soil group C = 0.000
Decimal fraction soil group D = 1.000
[INDUSTRIAL area type ]
Time of concentration = 8.69 min.
Rainfall intensity = 4.795(In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area. Rational method,Q=KCIA, C = 0.950
Subarea runoff = 1.822(CFS) for 0.400(Ac.)
Total runoff = 74.506(CFS) Total area = 15.14(Ac.)
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
Process from Point/Station 14.000 to Point/Station 15.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 253.840(Ft.)
Downstream point/station elevation = 251.890(Ft.)
Pipe length = 110.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 74.506(CFS)
Given pipe size = 36.00(In.)
Calculated individual pipe flow = 74.506(CFS)
Normal flow depth in pipe = 25.24(In.)
Flow top width inside pipe = 32.96(In.)
Critical Depth = 32.54(In.)
Pipe flow velocity = 14.07(Ft/s)
Travel time through pipe = 0.13 min.
Tirae of concentration (TC) = 8.82 min.
+ + + + + ++ +-1--I--I--(.-I--(--(- +-H-f.-h-H-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f
Process from Point/Station 14.000 to Point/Station 15.000
SUBAREA FLOW ADDITION ****
Deciraal 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
[INDUSTRIAL area type _ ]
Time of concentration = 8.82 min.
Rainfall intensity = 4.749(In/Hr) for a 100.0 year storra
Runoff coefficient used for sub-area. Rational raethod,Q=KCIA, C = 0.950
Subarea runoff = 1.714(CFS) for 0.380(Ac.)
Total runoff = 76.220(CFS) Total area = 15.52(Ac.)
+++++++-H-I--H+-H-I-+-H-I--I--f.-h-h-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f
Process from Point/Station 15.000 to Point/Station 16.000
PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 251.890(Ft.)
Downstream point/station elevation = 246.800(Ft.)
Pipe length = 24.80(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 76.220(CFS)
Given pipe size = 36.00(In.)
Calculated individual pipe flow = 7 6.220(CFS)
Norraal flow depth in pipe = 12.33(In.)
Flow top width inside pipe = 34.17(In.)
Critical Depth = 32.77(In.)
Pipe flow velocity = 35.63(Ft/s)
Travel time through pipe = 0.01 min.
Time of concentration (TC) = 8.84 min.
++++++-i--H++-H+-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+-i--i--l--l-+
Process from Point/Station 16.000 to Point/Station 17.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 246.470(Ft.)
Downstream point/station elevation = 221.620(Ft.)
Pipe length = 4 6.75(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 76.220(CFS)
Given pipe size = 36.00(In.)
Calculated individual pipe flow = 76.220(CFS)
Norraal flow depth in pipe = 9.63(In.)
Flow top width inside pipe = 31.87(In.)
Critical Depth = 32.77(In.)
Pipe flow velocity = 50.10(Ft/s)
Travel time through pipe = 0.02 min.
Time of concentration (TC) = 8.85 min.
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
Process from Point/Station 17.000 to Point/Station 18.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstreara point/station elevation = 220.620(Ft.)
Downstream point/station elevation = 220.260(Ft.)
Pipe length = 35.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 76.220(CFS)
Given pipe size = 48.00(In.)
Calculated individual pipe flow = 76.220(CFS)
Normal flow depth in pipe = 24.66(In.)
Flow top width inside pipe = 47.98(In.)
Critical Depth = 31.69(In.)
Pipe flow velocity = 11.72(Ft/s)
Travel tirae through pipe = 0.05 min.
Time of concentration (TC) = 8.90 min.
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
Process from Point/Station 17.000 to Point/Station 18.000
**** SUBAREA FLOW ADDITION ****
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
[INDUSTRIAL area type ]
Time of concentration = 8.90 min.
Rainfall intensity = 4.722 (In/Hr) for a 100.0 year storm
Runoff coefficient used for sub-area. Rational method,Q=KCIA, C = 0.950
Subarea runoff = 6.640{CFS) for 1.480(Ac.)
Total runoff = 82.860(CFS) Total area = 17.00(Ac.)
-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f-f+
Process from Point/Station 18.000 to Point/Station 19.000
**** PIPEFLOW TRAVEL TIME (User specified size) ****
Upstream point/station elevation = 220.260(Ft.)
Downstream point/station elevation = 219.970(Ft.)
Pipe length = 35.00(Ft.) Manning's N = 0.013
No. of pipes = 1 Required pipe flow = 82.8 60(CFS)
Given pipe size = 48.00(In.)
Calculated individual pipe flow = 82.860(CFS)
Normal flow depth in pipe = 27.75(In.)
Flow top width inside pipe = 47.41(In.)
Critical Depth = 33.11(In.)
Pipe flow velocity = 11.02(Ft/s)
Travel time through pipe = 0.05 min.
Time of concentration (TC) = 8.95 min.
End of computations, total study area = 25.530 (Ac.)
APPENDIX B
(4. TABLES AND CHARTS)
U/eS/?7^ 7?7?S7?S 0l^£yeL7?A//7> T/MS OF FLOW CU/e\7SS
£xo/np/£ ••
G/yen le/rg//} 0/" T'/otv ' JOO
S/ofi^ ' 70'A,
Coef/'/c/e/}/ 0/ eu/7o//. C'.SO
^eac/ • Ot'£/'/<fne/ /'/otv/Zme '/^ A///7C//<TS
i
I SAN DIEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
DESIGN MANUAL
URBAN AREAS OVERLAND TIME
OF FLOW CURVES
DATE APPENDIX X-C
CHART 3
EXHI3LT 2 (7/9)
Cur»
wiorrtvo)
i
TO Au-i7* f^cs C'J:/3OI.V3 CIVICS ? ca
CiSCHiPCE FS." SCUARE fCCr CP
I
I
...... ...,,.,.=..,3 HYDRA'JL'.C CAPACITY OF GRATE
pr.riiW INLET IN SUMP
INTENSITY-DUMTION DtSIGN CHART
la nnlli'lliliil i.i-i-»i4iiiliiinii;ii.ii.iimf=; • i . i'i j.i-j.i u.i-H»nirimi
j Equation: I = 7.44 D ''^^^
I = Intensity (In./Hr.)
» 6 Hr. Precipitation (In.)
' • :' • CTt I
o c -?
-J ro o
rt
O =1
3 n =r ro (/»
15 20
Minntfis
Directions for Application:
1) From precipitation naps determine 6 hr. and
24 hr. amounts for the selected frequency.
These maps are printed in the County Hydrology
Manual (10, 50 and 100 yr. maps included in the
Design and Procedure hjanual).
2) Adjust 6 hr. precipitation (if necessary) so
that it is within the range of 45% to 65% of
the 24 hr. precipitation. (Not applicable
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:
0) Selected Frequency ^r.
1) P. = Jn., ?2Br —
2) Adjusted *Pg= in.
%*
3) t^ =
4) I = .
min.
in/hr.
*Not Applicable to Desert Region
Revised 1/8.S APPFNDTX XT-A
V '.*nf Of SAM OIECO
OEPARINCffr OF SANITATION S
FLOOO CONTROL
^5*
33*
30'
15'
100-YEAf^^4-IIOljR PRECIPITATION
'•20^ISOPLUVIALS OF 100 -YEAR 24-HOUR
PRECIPITATIOH IM EMTHS OF AN IMCH
"15'
U.S. DEPARtllENtr
HATtOKAL OCKAMC AHO
irsctAL STuoiKs »«A.MOi. orncc or ii
30*
OF COMMERCE
AT^OSPIICNIC AOMRISTIIATtON
PMOkOCY. NATIONAI. »I:ATIIKII SCRVICC
nr.' I|5« 30* 117' l,r,i 30« 116'
W .nr OF SAN OIEGO
i,..ARTNENr OF SANITATIOM ft
FLOOO CONTROL
100-YEAft PRECIPITATI0?5
ISOPLUVIALS OF lOO-YEAR G-HOUR
PRECIPITATIOM IM EMTHS 0? AM liiCIl
ri»F«
U.S. DEPARTMEN
HAiiOMAL ecCAMC AMD AT9]osnieinc A^i^i^^f ^J3^!^ grtewu. ttwoiM ««As»eH. ornc« or II
30».
r OF COMMERCE
imOLOOV. NATIONAL VIATHKR SCKVICC
118 ^5' 30'
«4
s
TABLE 2
RUNOFF COEFFICIENTS (RATIONAL METHOD)
DEVELOPED AREAS (URBAN)
Land Use
Coefficient. C
SoiI Group (1)
Residential:
A B c D
Si ngle Family .^0 MS .50 •55
Multi-Units .^5 .50 .60 .70
Mobile homes M .50 .55 .65
-\
Rural (lots greater than 1/2 acre) .30 .35 % M
Commercial(2)
80% Impervious
.70 .75 .80 .85
Industrial (2)
90% Impervious
.80 .85 .90 .95
NOTES:
^'^Soil Group ma.r>s are available at the offices of the Departinent of Public Works.
(2)whe re actual conditions deviate significantly from the tabulated impervious-
ness values of 80% or 90%, the values given for coefficient C, may be revised
by multiplying 80% or 90% by the ratio of actual imperviousness to the
tabulated 'imperviousness. However, in no case shall the final coefficient
be less than 0.50. For example: Consider commercial property on D soiI. group.
Actual imperviousness • 50%
Tabulated imperviousness - 80%
Revised C - 50 X 0.85 - 0.53
80
.4- r-^* •
^^7^:\^m^W7^:
IV-A-9
APPENDIX IX-B- . ^. V .Rev.^; S/81 >
"A
Average Values of Roughness Coefficient (Manning's n)
Typa of Waterway
1. Closed Conduits (1)
Steel (not lined)
Cast Iron
Aluminum
Corrugated Metal
Corrugated Metal
Corrugated Metal
Corrugated Metal
Concrete RCP
Clay (sewer)
Asbestos Cement-^ Pv<i-
Drain Tile (terra cotta)
Cast-in-place Pipe
Reinforced Concrete Box
(not lined)
(2) (smooth asphalt quarterlining)
(2) (smooth asphalt half lining)
(smooth asphalt full lining)
Roughness
CoafficiBnt (n)
0.015
0.015
.021
0.024
0.021
0.018
0.012
0.012
0.013
0.011
0.015
0.015
0.014
2. Open Channels (1)
a. Unlined
Clay Loam
Sand
0.023
0.020
b. Revetted
Gravel
Rock
Pipe" and Wire
Sacked Concrete
c. Lined
Con^crete (poured)
Airv Blown Mortar (3)
Asphaltic Concrete or Bituminous Plant Mix
d. Vegetated (5)
Grass lined, maintained
Gra^s and Weeds
Grass lined with concrete low flow channel
3. Pavement and Gutters (1)
!
Concrete
Bituminous (plant-mixed)
^m'i^^;.:7.
0.030
0.040
0.025
0.025
0.014
0.016
0.018
.035
.045
.032
0.013
0.016
tmest F. Brater ind Horace Williams King
HANDBOOK OF
HYDRAULICS
For the Solulion of Hydraulic En
gineering Problems
Tabic 7-14. Values,of A" for Circular Cliannels in the Formula
tt
D - depth of water d « dianu trr of channel
b 1
d j .00
1
.01
.0 .00007
.1 .00907 .0118
•> .0400 .0448
.3 .0907 .0900
.4 .1501 .1033
.5 .232 .239
.6 .311 .319
.7 .388 .395
.8 .4^ .458
.9 .494 .496
1.6 .463
.02
.00031
.0142
.0402
.1027
.1705
247
.327
.402
463
497
.03
.00074
.0107
,0537
,108U
177U
255
335
409
408
498
.04
,00138
0195
0585
1153
1854
203
343
416
.473
498
.05
00222
.0225
.0034
.1218
.1929
.271
.350
.422
.477
498
.00
.0032S
.0257
.0080
.1284
,2005
279
358
429
481
496 "-
.07
.00455
.0291
.0738
.1352
.2082
.287
.300
.435
.485
.494
.08
.00004
.0327
.0793
.1420
.2100
.295
.373
.441
.488
.489
.09
APPENDIX C
(5. HYDROLOGY MAP)