HomeMy WebLinkAbout; Ocean Bluff Partnership; Ocean Bluff Partnership; 1993-09-03r
L Hunsaker & Associates San Diego, Inc.
Planning • Engineering • Surveying • GPS
PRELIMINARY
HYDROLOGY
STUDY
FOR
OCEAN BLUFF
CITY OF CARLSBAD
Prepared for:
Ocean Bluff Partnership
4370 La Jolla Village Drive Suite 120
San Diego, California 92122
September 3,1993
PREPARED UNDER THE SUPERVISION OF:
' t. / sf S,__, rs-^f! S\ , ~<^£Ji
GLEN K. VAN PESKI RCE41204 DATE
10179 Huennekens Street • San Diego, CA 92121 • (67.9; 558-4500 • MX-
Offices: San Diego • Inline • Riverside I San Bernardino
Dai -id Hammar • /«c/? /////
558-1414
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CONTENTS
Page
Introduction 1
Methodology 1
Results 3
Appendices
Appendix A 10-yr. Pre-Development Runoff Calculations
Appendix B 10-yr. Post-Development Runoff Calculations
Appendix C 100-yr. Pre-Development Runoff Calculations
Appendix D 100-yr. Post-Development Runoff Calculations
Appendix E Reference Materials
Portion Carlsbad Master Drainage Plan
SCS Soil Map
SCS Soil Table
Runoff Coefficients
Tc for Natural Watersheds
Tc for Urban Watersheds
10-yr. Isopluvial Charts
100-yr. Isopluvial Charts
Intensity-Duration-Frequency Chart
Pocket Hydrology Maps
Preliminary Hydrology Study
Ocean Bluff
Page I
Introduction The Ocean Bluff project is a rectangular property of 32 acres
located in Zone 20 in the City of Carlsbad. The property is
currently vacant, and has supported agricultural operations in
recent history. Adjacent properties are likewise either vacant
or supporting agricultural uses. Access to the site is by
Blackrail Road.
The Ocean Bluff site is the top of a hill, with the ground falling
away in all directions. The northwestern portion of the site
contains an area of approximately 3 acres that is separated
from the remainder of the site by a natural bank about 15 feet
high. A ridge running north-south divides the property, with
approximately two thirds of the property draining to the west
and one third to the east.
Development of the property results in the diversion of some of
the easterly drainage into the westerly drainage. This diversion
is to compensate for the increased runoff from development, to
minimize the impact of that development on runoff leaving the
site to the east. A temporary detention basin is anticipated for
the westerly drainage basin, to attenuate post-development
runoff to pre-development levels. Since the site is at the top of
the drainage, it is anticipated that in the future, a downstream,
regional detention basin will be constructed which will replace
the temporary onsite basin. The Master Drainage and Storm
Water Quality Management Plan for the City of Carlsbad
shows a detention basin, facility CFA, which will accept the >
westerly drainage from the Ocean Bluf
A rational hydrology program was used to determine the
amount of runoff from the site. The program by Advanced
Engineering Software is based on the San Diego County Flood
Control Hydrology Manual (1985). Hydrology maps were
prepared from aerial photography by Zenith Aerial dated April,
1987.
i
Methodology This report analyzes the pre-development and post-
development runoff for the Ocean Bluff project, consisting of
32 acres.
Runoff was calculated using the Rational method, through the
equation Q=CIA. "Q" describes the peak flow rate in cubic
feet per second (cfs). The coefficient of runoff "C", expressed
Preliminary Hydrology Study
Ocean Bluff
Page 2
the amount of runoff leaving the site, as a percentage, and
takes into account the hydrologic soil type and land uses
onsite. The Soil Conservation Service maps show the
predominant soil onsite as Chesterton fine spndy loam, which
has a hydrologic soil type "D" designation, indicating high
runoff potential.
The average rainfall intensity "I" is measured in inches per
hour, and is based on the time of concentration (Tc) for the
drainage area. The time of concentration is the time it takes
for the runoff to flow from the most remote point to the outfall
of the drainage basin. Tc is calculated differently for natural
watersheds and developed watersheds, according to Appendix
X-A and X-C in the County Manual. The precipitation for the
10-yr. and 100-yr. storms were determined from the County
isopluvial charts.
The area of the drainage basin "A", was calculated by
determining the limits of the drainage basins on either the pre-
development or post-development drainage basins, and
digitizing the area in acres.
Rainfall is modeled from an initial basin, routed through pipes
or streets, and subareas are added in. Where different flow
paths come together, the peak flows are confluence to
determine a resultant peak flow.
Preliminary Hydrology Study
Ocean Bluff
Page 3
Results The summary of the preliminary hydrology calculations is as
follows:
Runoff
Pre-development
Post development
West
Q10
23.45
21.70
Q100
37.24
34.47
East /
010
10.101
8.58
Q100
16.04
18.34
Total /
Q10 ,
33.55 '
30.28
'Q100
53.28
52.81
Based on the preliminary calculations, the increase in the runoff
coefficient "C" from development is compensated for by the
increased times of concentration "Tc" from the proposed
grading which creates longer flow paths and flatter grades.
The final hydrology study will examine the flows in more
detail, and size the detention basin if it is required.
VICINITY MAP
NO SCALE
-STATE OF CALIFORNIA
TMRNT OF WATER RESOURCES
C.A
7.5 Ml
PRELIMINARY HYDROLOGY STUDY
OCEAN BLUFF
APPENDIX A
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-92 Advanced Engineering Software (aes)
Ver. 1.3A Release Date: 3/06/92 License ID 1239
•
Analysis prepared by:
HUNSAKER & ASSOCIATES
Irvine , Inc.
Planning * Engineering * Surveying
Three Hughes, Irvine, California 92718 Ph. 714-583-1010
FILE NAME: B:OB10PRE.DAT
TIME/DATE OF STUDY: 15:22 8/ 5/1993
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
1985 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 10.00
6-HOUR DURATION PRECIPITATION (INCHES) = 1.700
SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = .90
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED
NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED
****************************************************************************
FLOW PROCESS FROM NODE 1.10 TO NODE 1.20 IS COD^= 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYS~IS<<<<T
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION
WITH 10-MINUTES ADDED = 13.45(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 900.00
UPSTREAM ELEVATION = 376.00
DOWNSTREAM ELEVATION = 278.00
ELEVATION DIFFERENCE =98.00
10 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.366
SUBAREA RUNOFF(CFS) = l2.35^> '*.
TOTAL AREA(ACRES) = 11.60 TOTAL RUNOFF(CFS) = 12.35
FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION
WITH 10-MINUTES ADDED = 11.10(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 220.00
UPSTREAM ELEVATION = 378.00
DOWNSTREAM ELEVATION = 350.00
ELEVATION DIFFERENCE = 28.00
10 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.678
SUBAREA RUNOFF(CFS) » 2.17
TOTAL AREA(ACRES) = 1.80 TOTAL RUNOFF(CFS) = 2.17
FLOW PROCESS FROM NODE 3.10 TO NODE 3.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION
WITH 10-MINUTES ADDED = 12.22(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 440.00
UPSTREAM ELEVATION = 376.00
DOWNSTREAM ELEVATION = 340.00
ELEVATION DIFFERENCE - 36.00
10 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.517
SUBAREA RUNOFF(CFS) = 7.93
TOTAL AREA(ACRES) = 7.00 TOTAL RUNOFF(CFS) = 7.93
FLOW PROCESS FROM NODE 4.10 TO NODE 4.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION
WITH 10-MINUTES ADDED = 14.59(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 1020.00
UPSTREAM ELEVATION = 372.00
DOWNSTREAM ELEVATION = 304.00
ELEVATION DIFFERENCE = 68.00
10 YEAR RAINFALL INTENSITY(INCH/HOUR) « 2.245
SUBAREA RUNOFF(CFS) = 9.09
TOTAL AREA(ACRES) = 9.00 TOTAL RUNOFF(CFS) = 9.09
FLOW PROCESS FROM NODE 5.10 TO NODE 5.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION
WITH 10-MINUTES ADDED = 12.49(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 430.00
UPSTREAM ELEVATION - 371.00
DOWNSTREAM ELEVATION = 346.00
ELEVATION DIFFERENCE = 25.00
10 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.482
SUBAREA RUNOFF(CFS) = 2.01
TOTAL AREA(ACRES) = 1.80 TOTAL RUNOFF(CFS) = 2.01
END OF STUDY SUMMARY:
PEAK FLOW RATE(CFS) = 2.01 Tc(MIN.) = 12.49
TOTAL AREA(ACRES) = 1.80
END OF RATIONAL METHOD ANALYSIS
PRELIMINARY HYDROLOGY STtJDY
OCEAN BLUFF
APPENDIX B
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-92 Advanced Engineering Software (aes)
Ver. 1.3A Release Date: 3/06/92 License ID 1239
tAnalysis prepared by:
HUNSAKER & ASSOCIATES
Irvine , Inc.
Planning * Engineering * Surveying
Three Hughes, Irvine, California 92718 Ph. 714-583-1010
FILE NAME: B:OB100PRE.DAT
TIME/DATE OF STUDY: 15:31 8/ 5/1993
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
1985 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT (YEAR) =(100.00^
6-HOUR DURATION PRECIPITATION (INCHESt-^ 2.700
SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE - .90
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED
NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED
FLOW PROCESS FROM NODE 1.10 TO NODE 1.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION
WITH 10-MINUTES ADDED = 13.45(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 900.00
UPSTREAM ELEVATION = 376.00
DOWNSTREAM ELEVATION = 278.00
ELEVATION DIFFERENCE = 98.00
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.757
SUBAREA RUNOFF(CFS) = 19.61
TOTAL AREA(ACRES) = 11.60 TOTAL RUNOFF(CFS) = 19.61
FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION
WITH 10-MINUTES ADDED = 11.10(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 220.00
UPSTREAM ELEVATION = 378.00
DOWNSTREAM ELEVATION = 350.00
ELEVATION DIFFERENCE = 28.00
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.253
SUBAREA RUNOFF(CFS) = 3.45
TOTAL AREA(ACRES) = 1.80 TOTAL RUNOFF(CFS) = 3.45
^ FLOW PROCESS FROM NODE 3.10 TO NODE 3.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION
WITH 10-MINUTES ADDED = 12.22(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 440.00
UPSTREAM ELEVATION = 376.00
DOWNSTREAM ELEVATION « 340.00
ELEVATION DIFFERENCE = 36.00
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.997
SUBAREA RUNOFF(CFS) = 12.59
TOTAL AREA(ACRES) =* 7.00 TOTAL RUNOFF(CFS) = 12.59
FLOW PROCESS FROM NODE 4.10 TO NODE 4.20 IS CODE - 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION
WITH 10-MINUTES ADDED = 14.59(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 1020.00
UPSTREAM ELEVATION = 372.00
DOWNSTREAM ELEVATION = 304.00
ELEVATION DIFFERENCE = 68.00
100 YEAR RAINFALL INTENSITY(INCH/HOUR) - 3.565
SUBAREA RUNOFF(CFS) = 14.44
TOTAL AREA(ACRES) = 9.00 TOTAL RUNOFF(CFS) = 14.44
- FLOW PROCESS FROM NODE 5.10 TO NODE 5.20 IS CODE = 21
** >»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION
WITH 10-MINUTES ADDED = 12.49(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 430.00
UPSTREAM ELEVATION = 371.00
DOWNSTREAM ELEVATION = 346,00
ELEVATION DIFFERENCE = 25.00
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.942
SUBAREA RUNOFF(CFS) = 3.19
TOTAL AREA(ACRES) = 1.80 TOTAL RUNOFF(CFS) = 3.19
END OF STUDY SUMMARY:
PEAK FLOW RATE(CFS) = 3.19 Tc(MIN.) = 12.49
TOTAL AREA(ACRES) = 1.80
END OF RATIONAL METHOD ANALYSIS
PRELIMINARY HYDROLOGY STUDY
OCEAN BLUFF
APPENDIX C
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-92 Advanced Engineering Software (aes)
Ver. 1.3A Release Date: 3/06/92 License ID 1239
Analysis prepared by:
HUNSAKER & ASSOCIATES
Irvine , Inc.
Planning * Engineering * Surveying
Three Hughes, Irvine, California 92718 Ph. 714-583-1010
FILE NAME: B:OB10PST.DAT
TIME/DATE OF STUDY: 16: 3 8/ 5/1993
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
1985 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 10.00
6-HOUR DURATION PRECIPITATION (INCHES) = 1.700
SPECIFIED MINIMUM PIPE SIZE(INCH) ~ 18.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = .90
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED
NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED
FLOW PROCESS FROM NODE 3.10 TO NODE 3.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .5500
INITIAL SUBAREA FLOW-LENGTH = 750.00
UPSTREAM ELEVATION = 374.00
DOWNSTREAM ELEVATION = 347.70
ELEVATION DIFFERENCE = 26.30
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 17.846
*CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
*CAUTION: SUBAREA FLOWLENGTH EXCEEDS COUNTY
NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
10 YEAR RAINFALL INTENSITY(INCH/HOUR) = 1.971
SUBAREA RUNOFF(CFS) = 5.31 ^——C
TOTAL AREA(ACRES) = 4.90 TOTAL RUNOFF(CFS) = ( 5.31
FLOW PROCESS FROM NODE 3.20 TO NODE 3.30 IS CODE =
>»»COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<««
>»»USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW) «<«
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS
PIPEFLOW VELOCITY(FEET/SEC.) = 10.1
UPSTREAM NODE ELEVATION = 347.70
DOWNSTREAM NODE ELEVATION = 332.00
FLOWLENGTH(FEET) = 340.00 MANNING'S
ESTIMATED PIPE DIAMETER(INCH) = 18.00
PIPEFLOW THRU SUBAREA(CFS) = 5.31
TRAVEL TIME(MIN.) = .56 TC(MIN.)
6.1 INCHES
N = .013
NUMBER OF PIPES
= 18.41
FLOW PROCESS FROM NODE 3.30 TO NODE 3.30 IS CODE
>»»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<««
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 18.41
RAINFALL INTENSITY(INCH/HR) = 1.93
TOTAL STREAM AREA(ACRES) = 4.90
PEAK FLOW RATE(CFS) AT CONFLUENCE =
FLOW PROCESS FROM NODE 5,10 TO NODE 5.20 IS CODE = 21
»>»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .5500
INITIAL SUBAREA FLOW-LENGTH = 550.00
UPSTREAM ELEVATION = 373.50
DOWNSTREAM ELEVATION = 343.00
ELEVATION DIFFERENCE = 30.50
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 13.118
*CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
*CAUTION: SUBAREA FLOWLENGTH EXCEEDS COUNTY
NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
10 YEAR RAINFALL INTENSITYWNCH/HOUR) = 2.404
SUBAREA RUNOFF (CFS) = 1^1^
TOTAL AREA(ACRES) = 3.00 TOTAL RUNOFF(CFS) = 3.97
FLOW PROCESS FROM NODE 5.20 TO NODE 3.30 IS CODE
>»»COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<««
»»>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW) ««<
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 5.5 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 8.7
UPSTREAM NODE ELEVATION = 343.00
DOWNSTREAM NODE ELEVATION = 332.00
FLOWLENGTH(FEET) = 280.00 MANNING'S N « .013
ESTIMATED PIPE DIAMETER (INCH) = lB-~QS__^ NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) - (3.97^
TRAVEL TIME (MIN.) = .53 TO(HIW<T= 13.65
FLOW PROCESS FROM NODE 3.30 TO NODE 3.30 IS CODE =
>»»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<««
>»»AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES«<«
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM
TIME OF CONCENTRATION(MIN.) = 13.65
RAINFALL INTENSITY(INCH/HR) = 2.34
TOTAL STREAM AREA(ACRES) = 3.00
PEAK FLOW RATE(CFS) AT CONFLUENCE = 3.97
2 ARE
** CONFLUENCE DATA **
STREAM RUNOFF Tc
NUMBER (CFS) (MIN.)
1 5.31 18.41
2 3.97 13.65
INTENSITY
(INCH/HOUR)
1.932
2.343
AREA
(ACRE)
4.90
3.00
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc
NUMBER (CFS) (MIN.)
1 8.35 13.65
2 8.58 18.41
INTENSITY
(INCH/HOUR)
2.343
1.932
COMPUTED CONFLUENCE ESTIMATES^RE AS FOLLOWS:
PEAK FLOW RATE(CFS)= STslT) Tc(MIN.) =
TOTAL AREA(ACRES) =
18.41
FLOW PROCESS FROM NODE 3.30 TO NODE 3.40 IS CODE =
>»»COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<««
>»»USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW) <««
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 9.8 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 8.7
UPSTREAM NODE ELEVATION = 332.00
DOWNSTREAM NODE ELEVATION = 330.00
FLOWLENGTH(FEET) = 90.00
ESTIMATED PIPE DIAMETER(INCH)
PIPEFLOW THRU SUBAREA(CFS) =
TRAVEL TIME(MIN.) = .17 TCfMIN.) = 18.58
MANNING'S
= 18.00
8.58
TC(MIN.)
N = .013
NUMBER OF PIPES =
FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .5500
INITIAL SUBAREA FLOW-LENGTH = 1000.00
UPSTREAM ELEVATION - 374.00
DOWNSTREAM ELEVATION « 344.00
ELEVATION DIFFERENCE - 30.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 21.708
*CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
*CAUTION: SUBAREA FLOWLENGTH EXCEEDS COUNTY
NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
10 YEAR RAINFALL INTENSITY(INCH/HOUR) =* 1.737
SUBAREA RUNOFF(CFS) =6.78
TOTAL AREA(ACRES) = 7.10 TOTAL RUNOFF(CFS) = 6.78
FLOW PROCESS FROM NODE 2.20 TO NODE 2.20 IS CODE
>»»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<««
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 21.71
RAINFALL INTENSITY(INCH/HR) = 1.74
TOTAL STREAM AREA(ACRES) = 7.10
PEAK FLOW RATE(CFS) AT CONFLUENCE = 6.78
FLOW PROCESS FROM NODE 6.10 TO NODE 6.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .5500
INITIAL SUBAREA FLOW-LENGTH = 780.00
UPSTREAM ELEVATION = 353.00
DOWNSTREAM ELEVATION = 344.00
ELEVATION DIFFERENCE == 9.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 26.361
*CAUTION: SUBAREA FLOWLENGTH EXCEEDS COUNTY
NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
10 YEAR RAINFALL INTENSITY(INCH/HOUR) *= 1.533
SUBAREA RUNOFF(CFS) = 5.90
TOTAL AREA(ACRES) = 7.00 TOTAL RUNOFF(CFS) = 5.90
FLOW PROCESS FROM NODE 6.20 TO NODE 2.20 IS CODE =
>»»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<««
>»»AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<««
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM
TIME OF CONCENTRATION(MIN.) - 26.36
RAINFALL INTENSITY(INCH/HR) » 1.53
TOTAL STREAM AREA(ACRES) = 7.00
PEAK FLOW RATE(CFS) AT CONFLUENCE = 5.90
2 ARE
** CONFLUENCE DATA **
STREAM RUNOFF Tc
NUMBER (CFS) (MIN.)
INTENSITY
(INCH/HOUR)
AREA
(ACRE)
6.78
5.90
21.71
26.36
1.737
1.533
7.10
7.00
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc
NUMBER (CFS) (MIN.)
1 11.99 21.71
2 11.89 26.36
INTENSITY
(INCH/HOUR)
1.737
1.533
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS
PEAK FLOW RATE(CFS) - 11.99 Tc(MIN.) -
TOTAL AREA(ACRES) = 14.10
21.71
FLOW PROCESS FROM NODE 2.20 TO NODE 2.30 IS CODE =
>»»COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<««
>»»USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<««
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 9.4 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 12.9
UPSTREAM NODE ELEVATION = 344.00
DOWNSTREAM NODE ELEVATION = 306.00
FLOWLENGTH(FEET) « 750.00 MANNING'S N = .013
ESTIMATED PIPE DIAMETER(INCH) » 18.00 NUMBER OF PIPES » 1
PIPEFLOW THRU SUBAREA(CFS) - 11.99
TRAVEL TIME(MIN.) = .97 TC(MIN.) = 22.68
FLOW PROCESS FROM NODE 1.10 TO NODE 2.30 IS CODE = 8
>»»ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<««
10 YEAR RAINFALL INTENSITY(INCH/HOUR) = 1.689
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
SUBAREA AREA(ACRES) = 3.60 SUBAREA RUNOFF(CFS) = 2.74
TOTAL AREA(ACRES) = 17.70 TOTAL RUNOFF(CFS) = 14.73
TC(MIN) = 22.68
FLOW PROCESS FROM NODE 4.10 TO NODE 4.20 IS CODE = 21
»>»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .5500
INITIAL SUBAREA FLOW-LENGTH = 620.00
UPSTREAM ELEVATION = 344.00
DOWNSTREAM ELEVATION = 313.00
ELEVATION DIFFERENCE = 31.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 14.417
*CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
*CAUTION: SUBAREA FLOWLENGTH EXCEEDS COUNTY
NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
10 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.262
SUBAREA RUNOFF(CFS) « 6.97
TOTAL AREA(ACRES) « 5.60 TOTAL RUNOFF(CFS) = 6.97
END OF STUDY SUMMARY:
PEAK FLOW RATE (CFS) =
TOTAL AREA (ACRES) =
6.97 Tc(MIN.) = 14.42
5.60
END OF RATIONAL METHOD ANALYSIS
PRELIMINARY HYDROLOGY STUDY
OCEAN BLUFF
APPENDIX D
OS
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-92 Advanced Engineering Software (aes)
Ver. 1.3A Release Date: 3/06/92 License ID 1239
Analysis prepared by:
HUNSAKER & ASSOCIATES
Irvine , Inc.
Planning * Engineering * Surveying
Three Hughes, Irvine, California 92718 Ph. 714-583-1010
FILE NAME: B:OB100PST.DAT
TIME/DATE OF STUDY: 16: 5 8/ 5/1993
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
1985 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.700
SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = .90
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED
NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED
FLOW PROCESS FROM NODE 3.10 TO NODE 3.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .5500
INITIAL SUBAREA FLOW-LENGTH = 750.00
UPSTREAM ELEVATION = 374.00
DOWNSTREAM ELEVATION = 347.70
ELEVATION DIFFERENCE = 26.30
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 17.846
*CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
*CAUTION: SUBAREA FLOWLENGTH EXCEEDS COUNTY
NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.131
SUBAREA RUNOFF(CFS) = 8.44
TOTAL AREA(ACRES) = 4.90 TOTAL RUNOFF(CFS) = 8.44
FLOW PROCESS FROM NODE 3.20 TO NODE 3.30 IS CODE = 3
>»»COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<««
>»»USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW) <««
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 7.9 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 11.4
UPSTREAM NODE ELEVATION = 347.70
DOWNSTREAM NODE ELEVATION = 332.00
FLOWLENGTH(FEET) = 340.00 MANNING'S N
ESTIMATED PIPE DIAMETER(INCH) = 18.00
PIPEFLOW THRU SUBAREA(CFS) = 8.44
TRAVEL TIME(MIN.) = .50 TC(MIN.) = 18.34
= .013
NUMBER OF PIPES
FLOW PROCESS FROM NODE 3.30 TO NODE 3.30 IS CODE
>»»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<««
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM
TIME OF CONCENTRATION(MIN.) = 18.34
RAINFALL INTENSITY(INCH/HR) = 3.08
TOTAL STREAM AREA(ACRES) = 4.90
PEAK FLOW RATE(CFS) AT CONFLUENCE = 8.44
1 ARE:
FLOW PROCESS FROM NODE 5.10 TO NODE 5.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .5500
INITIAL SUBAREA FLOW-LENGTH - 550.00
UPSTREAM ELEVATION = 373.50
DOWNSTREAM ELEVATION = 343.00
ELEVATION DIFFERENCE = 30.50
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 13.118
*CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
*CAUTION: SUBAREA FLOWLENGTH EXCEEDS COUNTY
NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.819
SUBAREA RUNOFF(CFS) = 6.30
TOTAL AREA(ACRES) - 3.00 TOTAL RUNOFF(CFS) = 6.30
FLOW PROCESS FROM NODE 5.20 TO NODE 3.30 IS CODE =
»»>COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<««
>»»USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW) <««
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 7.0 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 9.9
UPSTREAM NODE ELEVATION = 343.00
DOWNSTREAM NODE ELEVATION = 332.00
FLOWLENGTH(FEET) = 280.00 MANNING'S N = .013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) = 6.30
TRAVEL TIME(MIN-) = .47 TC(MIN.) = 13.59
FLOW PROCESS FROM NODE 3.30 TO NODE 3.30 IS CODE =
>»»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<««
>»»AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES«<«
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM
TIME OF CONCENTRATION(MIN.) = 13.59
RAINFALL INTENSITY(INCH/HR) = 3.73
TOTAL STREAM AREA(ACRES) = 3.00
PEAK FLOW RATE(CFS) AT CONFLUENCE = 6.30
2 ARE:
** CONFLUENCE DATA **
STREAM RUNOFF Tc
NUMBER (CFS) (MIN.)
1 8.44 18.34
2 6.30 13.59
INTENSITY
(INCH/HOUR)
3.076
3.733
AREA
(ACRE)
4.90
3.00
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc
NUMBER (CFS) (MIN.)
1 13.25 13.59
2 13.63 18.34
INTENSITY
(INCH/HOUR)
3.733
3.076
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 13.63 Tc(MIN.) =
TOTAL AREA(ACRES) = 7.90
18.34
FLOW PROCESS FROM NODE 3.30 TO NODE 3.40 IS CODE =
>»»COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<««
>»»USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW) <««
DEPTH OF FLOW IN 18.0 INCH PIPE IS 13.6 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 9.5
UPSTREAM NODE ELEVATION = 332.00
DOWNSTREAM NODE ELEVATION = 330.00
FLOWLENGTH(FEET) = 90.00 MANNING'S
ESTIMATED PIPE DIAMETER(INCH) = 18.00
PIPEFLOW THRU SUBAREA(CFS) = 13.63
TRAVEL TIME(MIN.) = .16 TC(MIN.) = 18.50
N = .013
NUMBER OF PIPES =
FLOW PROCESS FROM NODE 2.10 TO NODE 2.20 IS CODE = 21
»>»RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
SOIL CLASSIFICATION IS "D"
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .5500
INITIAL SUBAREA FLOW-LENGTH = 1000.00
UPSTREAM ELEVATION = 374.00
DOWNSTREAM ELEVATION = 344.00
ELEVATION DIFFERENCE = 30.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 21.708
*CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
*CAUTION: SUBAREA FLOWLENGTH EXCEEDS COUNTY
NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.759
SUBAREA RUNOFF(CFS) = 10.78
TOTAL AREA(ACRES) = 7.10 TOTAL RUNOFF(CFS) = .10.78
FLOW PROCESS FROM NODE 2.20 TO NODE 2.20 IS CODE = 1
>»»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<««
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 21.71
RAINFALL INTENSITY(INCH/HR) = 2.76
TOTAL STREAM AREA(ACRES) = 7.10
PEAK FLOW RATE(CFS) AT CONFLUENCE = 10.78
FLOW PROCESS FROM NODE 6.10 TO NODE 6.20 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .5500
INITIAL SUBAREA FLOW-LENGTH = 780.00
UPSTREAM ELEVATION = 353.00
DOWNSTREAM ELEVATION = 344.00
ELEVATION DIFFERENCE = 9.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 26.361
*CAUTION: SUBAREA FLOWLENGTH EXCEEDS COUNTY
NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.435
SUBAREA RUNOFF (CFS) *= 9.37
TOTAL AREA(ACRES) = 7.00 TOTAL RUNOFF(CFS) = 9.37
FLOW PROCESS FROM NODE 6.20 TO NODE 2.20 IS CODE =
>»»DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<««
>»»AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<««
TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:
TIME OF CONCENTRATION(MIN.) = 26.36 .
RAINFALL INTENSITY(INCH/HR) = 2.43
TOTAL STREAM AREA(ACRES) = 7.00
PEAK FLOW RATE(CFS) AT CONFLUENCE = 9.37
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 10.78 21.71 2.759 7.10
9.37 26.36 2.435 7.00
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc
NUMBER (CFS) (MIN.)
1 19.04 21.71
2 18.88 26.36
INTENSITY
(INCH/HOUR)
2.759
2.435
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 19.04 Tc(MIN.) =
TOTAL AREA(ACRES) = 14.10
21.71
FLOW PROCESS FROM NODE 2.20 TO NODE 2.30 IS CODE =
»>»COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<««
>»»USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<««
DEPTH OF FLOW IN 18.0 INCH PIPE IS 12.7 INCHES
PIPEFLOW VELOCITY(FEET/SEC.} = 14.2
UPSTREAM NODE ELEVATION « 344.00
DOWNSTREAM NODE ELEVATION = 306.00
FLOWLENGTH(FEET) = 750.00 MANNING'S N = .013
ESTIMATED PIPE DIAMETER(INCH) * 18.00 NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) = 19.04
TRAVEL TIME(MIN.) = .88 TC(MIN.) = 22.59
FLOW PROCESS FROM NODE 1.10 TO NODE 2.30 IS CODE = 8
>»»ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<««
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.690
SOIL CLASSIFICATION IS "D"
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500
SUBAREA AREA(ACRES) » 3.60 SUBAREA RUNOFF(CFS) = 4.36
TOTAL AREA(ACRES) « 17.70 TOTAL RUNOFF(CFS) = 23.40
TC(MIN) = 22.59
FLOW PROCESS FROM NODE 4.10 TO NODE 4.20 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
SOIL CLASSIFICATION IS "D"
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .5500
INITIAL SUBAREA FLOW-LENGTH = 620.00
UPSTREAM ELEVATION = 344.00
DOWNSTREAM ELEVATION ~ 313.00
ELEVATION DIFFERENCE = 31.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 14.417
*CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
*CAUTION: SUBAREA FLOWLENGTH EXCEEDS COUNTY
NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.593
SUBAREA RUNOFF(CFS) = 11.07
TOTAL AREA(ACRES) = 5.60 TOTAL RUNOFF(CFS) = 11.07
END OF STUDY SUMMARY:
PEAK FLOW RATE(CFS) = 11.07 Tc(MIN.) = 14.42
TOTAL AREA(ACRES) = 5.60
END OF RATIONAL METHOD ANALYSIS
PRELIMINARY HYDROLOGY STUDY
OCEAN BLUFF
APPENDIX E
Ml.1
*^%&^w»e^ <TJo R^/p?7l^^k&A0^*rS7v ^ / rj^tam>i7.7% x
' /—••'vT3>>JM;M,« ^ao-RtfeiasinttPS<K
;i8rRcp/iG.W,:-Vtfxa.>-R^M)'W^I;A", i (ya^i/fcftill
feaiisih^
36HRCP/1.6%
36"RCP
18"RCP--
^ ' \
&|IVU"Rbp/8.8k
%^27"RdV7.4%
^2l"R5P/5-7rM'"*. x .. • \ I
"RCW
RCF .R9»-
"^wr"'i6"ftcrvb.J»--\\\
43WCry0.2K=
x" \\^» \E 'RCPV&.2?!«• -rmt \ ' - \ ,*"Av ;)'W\\-k^V_.t. ..' ' M«-.'t*-kJ
.((, '.'
^ I ^36l&|
,KM*8lfCf
8".ftCF*i-J!1?t^^
jo'rfc^/fe.dx
i27:RpN/4.8^,
fr» 27"RCF1 ''O.fefS
jgrA'fe^aikzx
7^Mv«i* !W-
*>-^"R4,
-*•!.' (Z*W/fl.*7%
^'•"^'lisS O,SK;
\
•*!60"RCP ;
^.4,-RCP/iO^ U ,• -1^ 4-R.Cp^ - \'-' >M>;. Mi \^nnn ^!*\^^ "'HFiH i II ^*vr *RW/?-D» ./i18RCF^r-2ro\ n ,/.
^•fcJ.^.-L^-M J•' *^>^J / II '> 1
SAI
TABLE 11.--INTERPRETATIONS FOR LAND MANAGKMKNT--Continued
Map
s ymho 1
Cul>2
CltB
CbC
CI)D
Chi!
CcC
CcK
CeC
CFB
CfC
Cfl)2
CgC
ChA
ChB
CkA
C1D2
Cll-2
CIG2
Cml:2
CmrG
Cnfi2
CnG2
Co
Cr
CsB
CsC
CsD
CtE
CtF
CuE
CuG
CvG
DaC
DaD
DaE
DaE2
DaF
Soil
['alpine coarse sandy loam, 9 to 15 percent slopes,
eroded.
Carlsbad gravelly loainy sand, 15 to 30 percent slopes
llarrizo very gravelly sand, 0 to 9 percent slopes
r'l «o »-rt ,**-rt t"; « A 1-11* Air Innm O frrt C *, ^*rt *- *• 1 nn » 0
Chesterton fine sandy loam, 5 to 9 percent slopes
Chesterton fine sandy loam, 9 to IS percent slopes,
e roded .
Chesterton-Urban land complex, 2 to 9 percent slopes:
"ieneba coarse sandy loam, 5 to 15 percent slopes,
eroded .
llieneba coarse sandy loam, 15 to 30 percent slopes,
eroded.
!:icneha coarse sandy loam, 30 to 65 percent slopes,
eroded.
;:ieneba rocky coarse sandy loam, 9 to 30 percent
slopes, eroded.
IMeneba very rocky coarse sandy loam, 30 to 75 percent
s 1 ope s .
:;ieneba-Fal Ibrook rocky sandy loams, 9 to 30 percent
slopes, eroded:
IMeneba-Fal Ibrook rocky sandy loams, 30 to 65 percent
slopes, eroded:
'rouch rocky coarse sandy loam, 5 to 30 percent
slopes,
kronen rocky coarse sandy loam, 30 to 70 percent
slopes.
:rouch stony fine sandy loam, 30 to 75 percent
slopes.
Hydro -
logic
group
B
C
C
C
C
D
I)
A
1)
D
D
D
D
C
C
C
B
B
B
B
B
B
C
B
C
D
A
A
A
A
B
B
B
B
B
D
D
D
D
D
lirodlbllity
Moderate 2
Severe 2
r; _ , o
Severe 9
c Q
Severe 16
Severe 16
Moderate 2 —
Severe 16
Severe 16
Severe 16
Severe 16
Severe 16
Moderate 2
Severe 2
Severe 16
Severe 16
Severe 1
Qli aht
Slioht -
Limitations for
conversion
from brush to
grass
Slight. 4/
Slight.
S 1 i ght .
Slight.
Slight.
Slight.
Slight.
Moderate.
Slight.
Slight.
Moderate.
Severe.
Severe.
Severe.
Severe.
Severe.
Severe.
Severe.
Severe.
Severe ,
Slight.
Slight.
Slight.
Slight.
SI i glit.
Moderate .
Moderate.
Moderate.
Moderate.
Slight. I/
Slight. }/
Slight. I/
Slight. I/
Moderate. I/
I
I
I
T
See footnotes at end of table.
TABU- ll.--TNTnRPRRTATIONS FOR LAND MANAGfiMHNT--Continued
Map
pytnho
LfP
IpR
I.PC
i.pr:2
LpM2
I,pf!2
l.rf:
\.r\\2
LrC
I,sn
I.SP
1,u
l.vP3
Md
MIC
Mil!
Mn A
MnR
MoA
MpA2
MrG
HvA
MvC
Mvl)
MxA
01 iC
OhP.
OhP
OK
Ok!:
YAvc
YC2
Vf)2
TA
PfC
Py
Soil
l.ns Flores-Urbnn Innd complex, 9 to 30 percent slopes:
l.as Po?fis fine sandy loam, 5 to 9 percent slopes,
eroded.
Las Posas fine sandy loam, 9 to 15 percent slopes,
eroded.
Las Posas fine sandy loam, 15 to 30 percent slopes,
eroded.
L.TS Posas stony fine sandy loam, 9 to 30 percent
slopes .
l.ns Posas stony fine sandy loam, 9 to 30 percent
slopes, eroded,
l.ns Posas stony fine sandy loam, 30 to 65 percent
slopes. '
Loamy alluvial land --
.onrny alluvial land- Hue rhuero complex, 9 to 50 percent
slopes, severely eroded:
Huerhuero
lottsvllle loamy coarse sand, wet, 0 to 2 percent
slopes.
niivenlirtin-Urban Innd complex, 2 to 9 percent slopes:
Hi venhain-Mrban land complex, !> to 30 percent slopes:
'Incentia sandy loam, thick surface, 0 to 2 percent
slopes.
'Incentia sandy loam, thick surface, 2 to 9 percent
s lopes .
llytlro-
logi c
group
D
D
U
I)
n
I)
n
n
I)
1)
C
C
B
U
D
D
A
A
B
B
D
B
D
A
A
A
n
1)
D
n
nn
n
D
D
D
iinn
n
n
Hrodihil i ty
\
Moderate 2
Moderate 2
Moderate 2
Moderate 1 —
Moderate 1 —
Moderate 1 —
Severe 16
Severe 1
Severe 2
Severe 16
Severe 16
Severe 16
Severe 16
Severe 16
Severe 16
Severe 9
Severe 16
Severe 16
Moderate 2
Limitations for
conversion
from brush to
grass
Slight.
Slight.
Slight.
Slight.
Slight.
Moderate.
Moderate.
Moderate.
Moderate.
Moderate.
SliEht.
Severe.
Severe.
Slight.
Slight.
Severe.
Slight, t\l
Slight. 4/
Slight. 4/
Slight. 3/
Slight.
Slight.
Moderate.
Slight.
Slight.
Slight.
Slight .
Si ight.
Slight.
Pee footnotes at end of table.
36
TABLE 2
RUNOFF COEFFICIENTS (RATIONAL METHOD)
DEVELOPED AREAS (URBAN)
Land Use
Residential:
Single Fami ly
Multi-Units
Mob! le homes
Rural (lots greater than 1/2 acre)
Commercial (2)
80% Impervious
Industrial^)
90% Impervious
80
Coefficient, C
SoiI Group (1)
A
40
45
45
30
70
B
.<*
.50
.50
.35
.75
C
.50
.60
.55
.40
.80
D
|-55
-70
.65
I5E
.85
85 90 95
NOTES;
^Soil Group mans are available at the offices of the Department of Public Works.
t^'Where 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 sol I.group
Actual imperviousness =* 50%
Tabulated imperviousness = 80%
Revised C • 12 x 9.85 » 0.53
80
IV-A-9
APPENDIX IX-B
Rev. 5/81
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— 200
M/nutes
— 24O
— /80
/20
— /OO
— 90
— 80
7/1— ffj
£ /)p-^— PIS
— S'O
— 40
— 30
— 20
— /0
— /£
— /4
— /?
— 9
— 3
7
— 6
"^
-*
— 3
H L Tc
SAN DIEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
DESIGN MANUAL
APPRnVFD '$.//, /^^s^-cH^
NOMOGRAPH FOR DETERMINATE
OF TIME OF CONCENTRATION (Tc)
FOR NATURAL WATERSHEDS
/ / /i 1DATF /2///*/ 1 APPFNDIX y-A
/?#£/? S T/Mf
SM0
£/vcf7 - L f/rpM of /r/ow - .500 &
S/00e •/.&•/<,
C0effa/e/t/ a/ fun of/. C - .SO
SAN DIEGO COUNTY
DEPARTMENT OF SPECIAL DISTRICT SERVICES
DESIGN MANUAL
APPROVED /i'' 'y- />^//'t 1-/r (.:' CV~T-
URBAN AREAS OVERLAND TIME
OF FLOW CURVES
APPENDIX X-C
IV-A-12
'JlQ
O.
X
X
COUNTY OF SAN DTEGO
DEPARTMENT OF SANITATION
FLOOD CONTROL
10-YEAR 6-HGUf PRECIPITATIQPJ
PREGIFITAT10W IN TEMTIIS OF AN INCH
' ^\N rv ,% i ] \\ \ ~t '_* J _\v_x\^vMt\t' i'i i \ ._i-23,^22 ^ i\\ t^J
APPENDIX XI-C
JTi T~
COUNTY OF SAN DIEGO .
DEPARTMENT OF SANITATION
FLOOD CONTROL 10-YEAR 24-HOUR PRECIPITATION
-20v ISOPLUVIALS
PRECIPITATION IN
OF 10-YEAR 24-HOUR
ENTHS OF AM IKCH
U.S. DEPARTMEr
OCEANIC AMD AT
SPECIAL STUDIES ORANCII. OKPICE OK II
14 by
T OF COMMERCE
ADMINISTRATION |
HOROLOGY. NATIONAL WEATHER SERVICE'
30
i i n i I 1—!r T—r
COUWTY OF SAN DIEGO
DEPARTMENT OF SANITATION
FLOOD CONTROL
1
33*
100-YEAR 6-
•2(U ISOPLUVIALS
P^ECIPITATIOfJ
OF 100-YEAR 6-HOUR
PRECIPITATION If* TEMTHS OF AN II
U.S. DEPARTMEN
NATTONAU OCEANIC AND AT
SPECIAL tTVOIES BRANCH. OFFICE OF 11
OSPIIEHIC ADUINHTRATION
>ROLOOY. NATIONAL WEATHER SERVIC1
30'.
I181
11 f i i i i : i
COUNTY OF SAN DIEGO
DEPARTMENT OF SANITATION
FLOOD CONTROL
33"
30'
15
1*5
U.S. DEPARTMEN
NATIONAL OCliAMC AND AT:.
SPECIAL STUDIES BKA.NCll. OFFICE O" II
30'
100-YEAR 24-HOIJR PRECIPITATION
^(UISQPLUVIALS Of 100 -YEAR 24-HOUR
PRECIPITATION IN 'EMTHS OF AN INCH
OM'MEHIC AOMIK1STRAT1ON
OKOtaCY. NATIU.NAL JftATIIER SERVICE
t i I
INTEHSITY-DUJVITIUN DESIGN CHART
7.44 P. D6
-.645
Intensity (In./llr.)
6 Ilr, Precipitation (In.)
Duration (Min.)
40 50 1
Directions for Applicatlon:
1) From precipitation naps determine 6 hr. and
24 hr. amounts for the selected frequency.
These maps are printed in the County Hydrolociy
Manual (10, 50 and 100 yr. maps included in tin
Design and Procedure Manual).
?.) Adjust 6 hr. precipitation (if necessary) so
that It Is within the range of 4555 to 6556 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 1ines.
5) This line is the intensity-duration curve for
the location being analyzed.
Applicafcion Form:
0) Selected Frequency yr
1)••P6 X*
P
2) Adjusted
31 tc=—L
24
in.
nun.
1) I _in/hr.
*Not Applicable to Desert Region
AI'I'I-NMIX XI
[V A-1-1