HomeMy WebLinkAboutCT 02-21; VILLAGES OF LA COSTA GREENS 1.12; TENTATIVE MAP HYDROLOGY STUDY; 2002-08-30HUNSAKER
^ASSOCIATES
SAN DIECO, INC.
PLANNING
ENGINEERINC
SURVEYING
IRVINE
RIVERSIDE
SAN DIEGO
TENATIVE MAP
HYDROLOGY STUDY
for
LA COSTA GREENS
PLANNING AREA 1.12
City of Carlsbad, California
Prepared for:
Real Estate Collateral Management Company
c/o Morrow Development
1903 Wright Place
Suite 180
Carlsbad, CA 92008
w.o. 235:
DAVE HAMMAR
LEX WILLIMAN
ALISA VIALPANDO
DANA SEGUIN
Eric Mosolgo, R.C.E.
Water Resources Manager
10179 Huennekenl;^nsaker& Associates San Diego, Inc
San Diego, CA 92121
(858) 558-4500 PH
(858)558-1414 FX
www,Hunsal<erSD,com
lnfo@HunsakerSD.com
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Hydrology Study
La Costa Greens- Planning Area 1.12
TABLE OF CONTENTS
SECTION
Executive Summary
Introduction
Proposed Conditions
Summary of Results
References
Methodology
Rational Method
50-Year, 6-Hour Rainfall Isopluvial Map
Developed Condition Rational Method Analysis III
50-Year, 6-Hour AES Model Output
Developed Condition Hydrology Map (Pocket)
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Hydrology Study
La Costa Greens- Planning Area 1.12
EXECUTIVE SUMMARY
Introduction
This hydrology will address onsite 50-year peak flow rates for the post-developed
condition ofthe La Costa Greens, Planning Area 1.12.
The La Costa Greens, Planning Areas 1.08-1.14, are located south ofthe proposed
extension of Poinsettia Lane and north of Alga Road along the proposed Alicante
Road in the City of Carlsbad, California (See Vicinity Map below).
OF
MARCOS
PROJECT
SITE
VICINITY MAP
NTS
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Hydrology Study
La Costa Greens- Planning Area 1.12
Proposed Condition
Development ofthe site will include the construction of single-family units along with
the associated streets, sidewalks, and internal storm drain systems. Runoff from the
site will be conveyed by 2 storm drain systems. One portions ofthe site drains to the
north into the storm drain along proposed Street "C", eventually collecting flow from
Planning Area 1.09 and confluencing with the Alicante storm drain system. This
system flows northerly before confluencing with a culvert just south ofthe proposed
extension of Poinsettia Lane and drains through the golf course. The remaining
portion of the site drains to the south where the flow is collected in a pipe draining
easterly, collecting flow from Planning Areas 1.13 and 1.14 before discharging into
the Alga Road storm drain and eventually Batiquitos Lagoon.
Summarv of Results
This hydrology study was performed using the County Method for Hydrology,
wherein the 50-year, 6-hour storm precipitation for the La Costa Greens site is
approximately 2.6 inches and a runoff coefficient of 0.46 based on a dwelling unit
per acre ratio less than 2.
A total of 18 cfs draining 12.0 acres drains to the south into the Alga Road storm
drain system and a total of 16 cfs draining 12.3 acres drains to the north into the
Alicante storm drain system.
For existing condition and offsite analysis, please referto "Hydrology Study for La
Costa Greens, Piiase I" prepared by O'Day Consultants.
References
"Drainage Design and Procedure Manuaf, County of San Diego, April 1993.
"Design and Procedure Manual for Flood Control and Drainage", County of San
Diego, revised April 1993.
"San Diego l-lydrology Manual", County of San Diego, draft September 2001.
"Hydrology Study for La Costa Greens, Phase I" O'Day Consultants.
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Hydrology Study
La Costa Greens- Planning Area 1.12
METHODOLOGY & MODEL DEVELOPMENT
Drainage Desiqn Criteria
ss than 1 square mile, the storm drain system shall be designed
combinatwn of storm drain system capacity and overflow can convey the
frequencyjform without damage of adjacent existing buildings or potential
criteria for the underground storm drain system shall be based
requency storm. Type D soil shall be assumed for all areas.
If no established storm discharge flows are available, then the Rational Method shall
be used to detennine peak discharge rates.
The onsite areas are presented on 1" = 40' scale hydrology map. All proposed and
existing drainage facilities, as well as drainage courses, have been denoted on this
map. For each drainage basin, the 100-year runoff and drainage area to each catch
basin is noted.
Rational Method Hvdrologic Analvsis
Computer Software Package - AES-99
Design Storm - 100-year return interval
Land Use - Single-family residential and open space onsite; residential
developments and paved areas offsite.
Soil Type - Hydrologic Soil Group D was assumed for all areas. Group D soils have
very slow infiltration rates when thoroughly wetted. Consisting chiefly of clay soils
with a high swelling potential, soils with a high permanent water table, soils with clay
pan or clay layer at or near the surface, and shallow soils over nearly impervious
materials. Group D soils have a very slow rate of water transmission.
Runoff Coefficient - In accordance with the County of San Diego standards, single-
family residential areas were designated a runoff coefficient of 0.55 while natural
areas were designated a runoff coefficient of 0.45. When a watershed encompassed
solely pavement conditions, a runoff coefficient of 0.95 was selected.
Rainfall Intensity - Initial time of concentration values were determined using the
County of San Diego's overland flow nomograph for urban and natural areas. Per
City of Oceanside, California standards, a maximum 5-minute time increment is
added to the initial natural sub basins. Downstream Tc values are determined by
adding the initial natural sub basin time of concentration and the downstream routing
time. Intensity values were determined from the Intensity-Duration Frequency curve
chart from the County of San Diego's Drainage Design Manual.
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Hydrology Study
La Costa Greens- Planning Area 1.12
Method of Analysis - The Rational Method is the most widely used hydrologic model
for estimating peak runoff rates. Applied to small urban and semi-urban areas with
drainage areas less than 0.5 square miles, the Rational Method relates storm rainfall
intensity, a runoff coefficient, and drainage area to peak runoff rate. This
relationship is expressed by the equation:
Q = CIA, where:
Q = The peak runoff rate in cubic feet per second at the point of
analysis.
C = A runoff coefficient representing the area - averaged ratio of
runoff to rainfall intensity.
I = The time-averaged rainfall intensity in inches per hour
corresponding to the time of concentration.
A = The drainage basin area in acres.
To perform a node-link study, the total watershed area is divided into subareas
which discharge at designated nodes.
The procedure for the subarea summation model is as follows:
(1) Subdivide the watershed into an initial sub area (generally 1 lot) and
subsequent sub areas, which are generally less than 10 acres in size. Assign
upstream and downstream node numbers to each sub area.
(2) Estimate an initial Tc by using the appropriate nomograph or overland flow
velocity estimation.
(3) Using the initial Tc, determine the corresponding values of I. Then Q = C I A.
(4) Using Q, estimate the travel time between this node and the next by
Manning's equation as applied to the particular channel or conduit linking the
two nodes. Then, repeat the calculation for Q based on the revised intensity
(which is a function of the revised time of concentration)
The nodes are joined together by links, which may be street gutter flows, drainage
swales, drainage ditches, pipe flow, or various channel flows. The AES-99 computer
sub area menu is as follows:
SUBAREA HYDROLOGIC PROCESS
1. Confluence analysis at node.
2. Initial sub area analysis (including time of concentration calculation).
3. Pipeflow travel time (computer estimated).
4. Pipeflow travel time (user specified).
5. Trapezoidal channel travel time.
6. Street flow analysis through subarea.
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Hydrology Study
La Costa Greens- Planning Area 1.12
7. User - specified information at node.
8. Addition of subarea runoff to main line.
9. V-gutter flow through area.
10. Copy main stream data to memory bank
11. Confluence main stream data with a memory bank
12. Clear a memory bank
At the confluence point of two or more basins, the following procedure is used to
combine peak flow rates to account for differences in the basin's times of
concentration. This adjustment is based on the assumption that each basin's
hydrographs are triangular in shape.
(1) . If the collection streams have the same times of concentration,
then the Q values are directly summed,
Qp = Qa + Qb; Tp = Ta = Tb
(2) . If the collection streams have different times of concentration,
the smaller of the tributary Q values may be adjusted as follows:
(i) . The most frequent case is where the collection stream
with the longer time of concentration has the larger Q.
The smaller Q value is adjusted by the ratio of rainfall
intensities.
Qp = Qa + Qb (la/lb); Tp = Ta
(ii) . In some cases, the collection stream with the shorter time
of concentration has the larger Q. Then the smaller Q is
adjusted by a ratio ofthe T values.
Qp = Qb + Qa (Tb/Ta); Tp = Tb
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Hydrology Study
La Costa Greens- Planning Area 1.12
CHAPTER 2
METHODOLOGY
50-Year, 6-Hour Rainfall Isopluvial Map
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Hydrology Study
La Costa Greens- Planning Area 1.12
CHAPTER 3
OLOGY
ur AES Output
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**************************************************^^^^^^^.J,J,.J^^^^^^^^^^^_^^^^^^
RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-99 Advanced Engineering Software (aes)
Ver. 1.5A Release Date: 01/01/99 License ID 1239
Analysis prepared by:
Hunsaker & Associates San Diego, Inc.
10179 Huennekens Street
San Diego, California (619) 558-4500
Planning Engineering Surveying
************************** DESCRIPTION OF STUDY **************************
* VILLAGES OF LA COSTA - NEIGHBORHOOD 1.12 *
* 50-YEAR DEVELOPED CONDITION HYDROLOGY ANALYSIS . *
* W.0.# 2352-0049 *
**************************************************************,^.J^,,J^J^.^J^J^.^..^..^.^.J^
FILE NAME: H:\AES99\2352\4 9\DEV50.DAT
TIME/DATE OF STUDY: 13: 2 8/30/2002
USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
1985 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 50.00
6-HOUR DURATION PRECIPITATION (INCHES) = 2.400
SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE =0.90
SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED
NOTE: ONLY PEAK CONFLUENCE VALUES CONSIDERED
+ +
I I
I BEGIN SOUTHERN SUBAREA |
I I + +
****************************************************************************
FLOW PROCESS FROM NODE 1.00 TO NODE 2.00 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
•USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4 600
INITIAL SUBAREA FLOW-LENGTH = 470.00
UPSTREAM ELEVATION = 369.50
DOWNSTREAM ELEVATION = 347.00
ELEVATION DIFFERENCE = 22,50
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 14,819
•CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.138
SUBAREA RUNOFF(CFS) = 1.96
TOTAL AREA(ACRES) = 1.36 TOTAL RUNOFF(CFS) = 1.96
****************************************************************************
FLOW PROCESS FROM NODE 2.00 TO NODE 3.00 IS CODE = 6
»»>COMPUTE STREETFLOW TRAVELTIME THRU SUBAREA««<
UPSTREAM ELEVATION = 347.00 DOWNSTREAM ELEVATION = 344.00
STREET LENGTH(FEET) = 200.00 CURB HEIGHT(INCHES) = 6.
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK = 14.00
INTERIOR STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
••TRAVELTIME COMPUTED USING MEAN FLOW{CFS) = 2.40
STREETFLOW MODEL RESULTS:
STREET FLOWDEPTH(FEET) = 0.31
HALFSTREET FLOODWIDTH(FEET) = 9.07
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.55
PRODUCT OF DEPTH&VELOCITY = 0.78
STREETFLOW TRAVELTIME(MIN) = 1.31 TC(MIN) = 16.13
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.971
•USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4600
SUBAREA AREA(ACRES) = 0.65 SUBAREA RUNOFF(CFS) = 0.88
SUMMED AREA(ACRES) = 2.00 TOTAL RUNOFF(CFS) = 2.84
END OF SUBAREA STREETFLOW HYDRAULICS:
DEPTH(FEET) =0.33 HALFSTREET FLOODWIDTH(FEET) = 9.96
FLOW VELOCITY(FEET/SEC.) = 2.56 DEPTH&VELOCITY = 0.83
****************************************************************************
FLOW PROCESS FROM NODE 3.00 TO NODE 4.00 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 ,4.0 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 9.6
UPSTREAM NODE ELEVATION = 344.00
DOWNSTREAM NODE ELEVATION = 343.00
FLOWLENGTH(FEET) = 15.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) = 2.84
TRAVEL TIME(MIN.) = 0.03 TC{MIN.) = 16.15
****************************************************************************
FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 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.) = 16.15
RAINFALL INTENSITY(INCH/HR) = 2.97
TOTAL STREAM AREA(ACRES) = 2.00
PEAK FLOW RATE(CFS) AT CONFLUENCE = 2.84
FLOW PROCESS FROM NODE 5.00 TO NODE 6.00 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
•USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4 600
INITIAL SUBAREA FLOW-LENGTH = 500.00
UPSTREAM ELEVATION = 394.00
DOWNSTREAM ELEVATION = 345.00
ELEVATION DIFFERENCE = 49.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 12.038
•CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
50 YEAR RAINFALL INTENSITY(INCH/HOUR) =3.588
SUBAREA RUNOFF(CFS) = 6.23
TOTAL AREA(ACRES) = 3.77 TOTAL RUNOFF(CFS) = 6.23
****************************************************************************
FLOW PROCESS FROM NODE 6.00 TO NODE 4.00 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 7.6 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 8.8
UPSTREAM NODE ELEVATION = 345.00
DOWNSTREAM NODE ELEVATION = 344.00
FLOWLENGTH(FEET) = 35.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) = 6.23
TRAVEL TIME(MIN.) = 0.07 TC(MIN.) = 12.10
****************************************************************************
FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 IS CODE = 1
»»>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.) = 12.10
RAINFALL INTENSITY{INCH/HR) = 3.58
TOTAL STREAM AREA(ACRES) = 3.77
PEAK FLOW RATE(CFS) AT CONFLUENCE = 6.23
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 2.84 16.15 2.968 2.00
2 6.23 12.10 3.575 3.77
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 8.58 12.10 3.575
2 8.01 16.15 2.968
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 8.58 Tc(MIN.) = 12.10
TOTAL AREA(ACRES) = 5.77
****************************************************************************
FLOW PROCESS FROM NODE 4.00 TO NODE 7.00 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 6.8 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 14.2
UPSTREAM NODE ELEVATION = 344.00
DOWNSTREAM NODE ELEVATION = 291.00
FLOWLENGTH(FEET) = 640.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) = 8.58
TRAVEL TIME(MIN.) = 0.75 TC(MIN,) = 12.86
****************************************************************************
FLOW PROCESS FROM NODE 7.00 TO NODE 7.00 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.) =12.8 6
RAINFALL INTENSITY(INCH/HR) = 3.44
TOTAL STREAM AREA(ACRES) = 5.77
PEAK FLOW RATE(CFS) AT CONFLUENCE = 8.58
****************************************************************************
FLOW PROCESS FROM NODE 8.00 TO NODE 9.00 IS CODE = 21
»>»RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
*USER SPECIFIED(SUBAREA):
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .3500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION (APPENDIX X-A)
WITH 10-MINUTES ADDED = 13.98(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 930.00
UPSTREAM ELEVATION = 415.00
DOWNSTREAM ELEVATION = 340.00
ELEVATION DIFFERENCE = 75.00
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.259
SUBAREA RUNOFF(CFS) = 1.15
TOTAL AREA(ACRES) = 1.01 TOTAL RUNOFF(CFS) = 1.15
****************************************************************************
FLOW PROCESS FROM NODE 9.00 TO NODE 10.00 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 2.4 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 8.2
UPSTREAM NODE ELEVATION = 34 0.00
DOWNSTREAM NODE ELEVATION = 300.00
FLOWLENGTH(FEET) = 440.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES
PIPEFLOW THRU SUBAREA(CFS) = 1.15
TRAVEL TIME(MIN.) = 0.90 TC(MIN.) = 14.87
****************************************************************************
FLOW PROCESS FROM NODE 10.00 TO NODE 10.00 IS CODE = 8
»»>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««<
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.130
*USER SPECIFIED(SUBAREA):
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .3500
SUBAREA AREA(ACRES) = 0.39 SUBAREA RUNOFF(CFS) = 0.4 2
TOTAL AREA(ACRES) = 1.40 TOTAL RUNOFF(CFS) = 1.58
TC(MIN) = 14.87
****************************************************************************
FLOW PROCESS FROM NODE 10.00 TO NODE 7.00 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 2.7 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 9.3
UPSTREAM NODE ELEVATION = 300.00
DOWNSTREAM NODE ELEVATION = 291.00
FLOWLENGTH(FEET) = 90.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) = 1.58
TRAVEL TIME(MIN.) = 0.16 TC(MIN.) = 15.03
****************************************************************************
FLOW PROCESS FROM NODE 7.00 TO NODE 7.00 IS CODE = 1
»»>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.) = 15.03
RAINFALL INTENSITY(INCH/HR) = 3.11
TOTAL STREAM AREA(ACRES) = 1.4 0
PEAK FLOW RATE(CFS) AT CONFLUENCE = 1.58
•• CONFLUENCE DATA ••
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 8.58 12.86 3.439 5.77
2 1.58 15.03 3.109 1.40
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
•• PEAK FLOW RATE TABLE ••
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 10.01 12.86 3.439
2 9.34 15.03 3.109
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 10.01 Tc(MIN.) = 12.8 6
TOTAL AREA(ACRES) = 7.17
****************************************************************************
FLOW PROCESS FROM NODE 7.00 TO NODE 7.00 IS CODE = 8
»»>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««<
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.439
•USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4500
SUBAREA AREA(ACRES) = 4.79 SUBAREA RUNOFF(CFS) = 7.41
TOTAL AREA(ACRES) = 11.96 TOTAL RUNOFF(CFS) = 17.42
TC(MIN) = 12.86
+ +
1 END OF SOUTHERN SUBAREA I
BEGIN OF NORTHERN SUBAREA
****************************************************************************
FLOW PROCESS FROM NODE 11.00 TO NODE 12.00 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<««
•USER SPECIFIED{SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4 600
INITIAL SUBAREA FLOW-LENGTH = 4 00.00
UPSTREAM ELEVATION = 360.00
DOWNSTREAM ELEVATION = 340.00
ELEVATION DIFFERENCE = 20.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 13.475
•CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.336
SUBAREA RUNOFF(CFS) = 3.01
TOTAL AREA(ACRES) = 1.96 TOTAL RUNOFF(CFS) = 3.01
************************************************************^^j^^^^.^^^^^^^j^^^
FLOW PROCESS FROM NODE 12.00 TO NODE 13.00 IS CODE = 6
»>»COMPUTE STREETFLOW TRAVELTIME THRU SUBAREA««<
UPSTREAM ELEVATION = 340.00 DOWNSTREAM ELEVATION = 304.00
STREET LENGTH(FEET) = 400.00 CURB HEIGHT(INCHES) = 6.
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK = 14.00
INTERIOR STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL{DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
••TRAVELTIME COMPUTED USING MEAN FLOW(CFS) = 3.71
STREETFLOW MODEL RESULTS:
STREET FLOWDEPTH(FEET) = 0.27
HALFSTREET FLOODWIDTH(FEET) = 7.29
AVERAGE FLOW VELOCITY(FEET/SEC.) = 5.71
PRODUCT OF DEPTH&VELOCITY = 1.55
STREETFLOW TRAVELTIME(MIN) = 1.17 TC(MIN) = 14.64
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.162
•USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4 600
SUBAREA AREA(ACRES) = 0.96 SUBAREA RUNOFF(CFS) = 1.40
SUMMED AREA(ACRES) = 2.92 TOTAL RUNOFF(CFS) = 4.41
END OF SUBAREA STREETFLOW HYDRAULICS:
DEPTH(FEET) = 0.29 HALFSTREET FLOODWIDTH(FEET) = 8.18
FLOW VELOCITY(FEET/SEC.) = 5.60 DEPTH&VELOCITY = 1.62
****************************************************************************
FLOW PROCESS FROM NODE 13.00 TO NODE 13.00 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.) = 14.64
RAINFALL INTENSITY(INCH/HR) = 3.16
TOTAL STREAM AREA(ACRES) = 2.92
PEAK FLOW RATE(CFS) AT CONFLUENCE = 4.41
**************************************************************^.j,.^j^^^^^.ji..^^^j^^
FLOW PROCESS FROM NODE 14.00 TO NODE 13.00 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
•USER SPECIFIED(SUBAREA):
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .3500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION (APPENDIX X-A)
WITH 10-MINUTES ADDED = 12.55(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 710.00
UPSTREAM ELEVATION = 410.00
DOWNSTREAM ELEVATION = 304.00
ELEVATION DIFFERENCE = . 106.00
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.4 93
SUBAREA RUNOFF(CFS) = 2.47
TOTAL AREA(ACRES) = 2.02 TOTAL RUNOFF(CFS) = 2.47
****************************************************************************
FLOW PROCESS FROM NODE 13.00 TO NODE 13.00 IS CODE = 1
»»>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.) = 12.55
RAINFALL INTENSITY(INCH/HR) = 3.4 9
TOTAL STREAM AREA(ACRES) = 2.02
PEAK FLOW RATE(CFS) AT CONFLUENCE = 2.47
•• CONFLUENCE DATA ••
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 4.41 14.64 3.162 2.92
2 2.47 12.55 3.493 2.02
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
•• PEAK FLOW RATE TABLE ••
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 6.46 12.55 3.493
2 6.65 14.64 3.162
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 6.65 Tc{MIN.) = 14.64
TOTAL AREA(ACRES) = 4.95
*********************************************^^J^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FLOW PROCESS FROM NODE 13.00 TO NODE 15.00 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 8.2 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 8.5
UPSTREAM NODE ELEVATION = 304.00
DOWNSTREAM NODE ELEVATION = 303.00
FLOWLENGTH(FEET) = 40.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) = 6.65
TRAVEL TIME(MIN.) = 0.08 TC(MIN.) = 14.72
*********************************************************,^,j^^^^.^j^^.j.^^^.j,.^j^^^^^
FLOW PROCESS FROM NODE 15.00 TO NODE 15.00 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.) = 14.72
RAINFALL INTENSITY(INCH/HR) = 3.15
TOTAL STREAM AREA(ACRES) = 4.95
PEAK FLOW RATE(CFS) AT CONFLUENCE = 6.65
****************************************************************
FLOW PROCESS FROM NODE 16.00 TO NODE 17.00 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
•USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4600
INITIAL SUBAREA FLOW-LENGTH = 480.00
UPSTREAM ELEVATION = 35 9.30
DOWNSTREAM ELEVATION = 354.00
ELEVATION DIFFERENCE = 5.30
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 24.419
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.274
SUBAREA RUNOFF(CFS) = 1.33
TOTAL AREA(ACRES) = 1.27 TOTAL RUNOFF(CFS) = 1.33
****************************************************************************
FLOW PROCESS FROM NODE 17.00 TO NODE 18.00 IS CODE = 6
»»>COMPUTE STREETFLOW TRAVELTIME THRU SUBAREA««<
UPSTREAM ELEVATION = 354.00 DOWNSTREAM ELEVATION = 304.00
STREET LENGTH(FEET) = 650.00 CURB HEIGHT{INCHES) = 6.
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK = 14.00
INTERIOR STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
••TRAVELTIME COMPUTED USING MEAN FLOW(CFS) = 2.24
STREETFLOW MODEL RESULTS:
STREET FLOWDEPTH(FEET) = 0.24
HALFSTREET FLOODWIDTH(FEET) = 5.51
AVERAGE FLOW VELOCITY(FEET/SEC.) = 5.32
PRODUCT OF DEPTH&VELOCITY = 1.26
STREETFLOW TRAVELTIME(MIN) = 2.04 TC(MIN) = 26.45
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.159
•USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4600
SUBAREA AREA(ACRES) = 1.84 SUBAREA RUNOFF(CFS) = 1.82
SUMMED AREA(ACRES) = 3.11 TOTAL RUNOFF(CFS) = 3.15
END OF SUBAREA STREETFLOW HYDRAULICS:
DEPTH(FEET) = 0.27 HALFSTREET FLOODWIDTH(FEET) = 7.29
FLOW VELOCITY(FEET/SEC.) = 4.86 DEPTH*VELOCITY = 1.32
************************************************************************^***
FLOW PROCESS FROM NODE 18.00 TO NODE 15.00 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 4.3 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 9.9
UPSTREAM NODE ELEVATION = 304.00
DOWNSTREAM NODE ELEVATION = 303.00
FLOWLENGTH(FEET) = 15.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) =3.15
TRAVEL TIME(MIN.) = 0.03 TC(MIN.) = 26.48
****************************************************************************
FLOW PROCESS FROM NODE 15.00 TO NODE 15.00 IS CODE = 1
»»>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.) = 26.48
RAINFALL INTENSITY(INCH/HR) = 2.16
TOTAL STREAM AREA(ACRES) = 3.11
PEAK FLOW RATE(CFS) AT CONFLUENCE = 3.15
** CONFLUENCE DATA *•
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 6.65 14.72 3.151 4.95
2 3.15 26.48 2.158 3.11
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
•* PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 8.81 14.72 3.151
2 7.71 26.48 2.158
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 8.81 Tc(MIN.) = 14.72
TOTAL AREA(ACRES) = 8.05
*****************************************************^^^^^.j^^^^^^.jj,^^^^^^^^^^^
FLOW PROCESS FROM NODE 15.00 TO NODE 19.00 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 6.6 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 15.0
UPSTREAM NODE ELEVATION = 303.00
DOWNSTREAM NODE ELEVATION = 260.00
FLOWLENGTH(FEET) = 450.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES =
PIPEFLOW THRU SUBAREA(CFS) = 8.81
TRAVEL TIME(MIN.) = 0.50 TC(MIN.) = 15.22
**************************************************************j^.^^^^.^..^.^.^.^.^^^^
FLOW PROCESS FROM NODE 19.00 TO NODE 19.00 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.) = 15.22
RAINFALL INTENSITY(INCH/HR) = 3.08
TOTAL STREAM AREA(ACRES) = 8.05
PEAK FLOW RATE(CFS) AT CONFLUENCE = 8.81
****************************************************************************
FLOW PROCESS FROM NODE 20.00 TO NODE 21.00 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
*USER SPECIFIED(SUBAREA):
RURAL DEVELOPMENT RUNOFF COEFFICIENT = .3500
NATURAL WATERSHED NOMOGRAPH TIME OF CONCENTRATION (APPENDIX X-A)
WITH 10-MINUTES ADDED = 11.24(MINUTES)
INITIAL SUBAREA FLOW-LENGTH = 340.00
UPSTREAM ELEVATION = 330.00
DOWNSTREAM ELEVATION = 255.00
ELEVATION DIFFERENCE = 75.00
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.74 9
SUBAREA RUNOFF(CFS) = 1.4 7
TOTAL AREA(ACRES) = 1.12 TOTAL RUNOFF(CFS) = 1.47
********************************************************j..j.j.^^j^^^^^^j^^^^^^^^^
FLOW PROCESS FROM NODE 21.00 TO NODE 19.00 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 4.3 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 4.6
UPSTREAM NODE ELEVATION = 261.00
DOWNSTREAM NODE ELEVATION = 260.00
FLOWLENGTH(FEET) = 70.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) = 1.47
TRAVEL TIME(MIN.) = 0.25 TC(MIN.) = 11.50
***********************************************************************.^.*.^.^.^
FLOW PROCESS FROM NODE 19.00 TO NODE 19.00 IS CODE = 1
»»>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.) = 11.50
RAINFALL INTENSITY(INCH/HR) = 3.70
TOTAL STREAM AREA(ACRES) = 1.12
PEAK FLOW RATE(CFS) AT CONFLUENCE = 1.47
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 8.81 15.22 3.084 8.05
2 1.47 11.50 3.696 1.12
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
•• PEAK FLOW RATE TABLE •*
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 8.82 11.50 3.696
2 10.04 15.22 3.084
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 10.04 Tc(MIN.) = 15.22
TOTAL AREA(ACRES) = 9.18
*******************************************************J,^^^^J,.^^^^^J.^^J^^^^^^^
FLOW PROCESS FROM NODE 19.00 TO NODE 22.00 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.) = 13.6
UPSTREAM NODE ELEVATION = 260.00
DOWNSTREAM NODE ELEVATION = 230.00
FLOWLENGTH(FEET) = 4 60.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES =
PIPEFLOW THRU SUBAREA(CFS) = 10.04
TRAVEL TIME(MIN.) = 0.57 TC(MIN.) = 15.78
************************************************************** ********.^.^.jj,jj,.^.^
FLOW PROCESS FROM NODE 22.00 TO NODE 22.00 IS CODE = 1
»»>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE««<
TOTAL NUMBER OF STREAMS = 3
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:
TIME OF CONCENTRATION(MIN.) = 15.78
RAINFALL INTENSITY(INCH/HR) = 3.01
TOTAL STREAM AREA(ACRES) = 9.18
PEAK FLOW RATE(CFS) AT CONFLUENCE = 10.04
****************************************************************************
FLOW PROCESS FROM NODE 23.00 TO NODE 24.00 IS CODE = 21
»»>RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
*USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4 600
INITIAL SUBAREA FLOW-LENGTH = 430.00
UPSTREAM ELEVATION = 297.00
DOWNSTREAM ELEVATION = 260.00
ELEVATION DIFFERENCE = 37.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 11.658
•CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.663
SUBAREA RUNOFF(CFS) = 2.08
TOTAL AREA(ACRES) = 1.24 TOTAL RUNOFF(CFS) = 2.08
****************************************************************************
FLOW PROCESS FROM NODE 24.00 TO NODE 25.00 IS CODE = 6
»»>COMPUTE STREETFLOW TRAVELTIME THRU SUBAREA<««
UPSTREAM ELEVATION = 260.00 DOWNSTREAM ELEVATION = 230.00
STREET LENGTH(FEET) = 450.00 CURB HEIGHT(INCHES) = 6.
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK = 14.00
INTERIOR STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
••TRAVELTIME COMPUTED USING MEAN FLOW(CFS) = 2.57
STREETFLOW MODEL RESULTS:
STREET FLOWDEPTH(FEET) = 0.25
HALFSTREET FLOODWIDTH(FEET) = 6.40
AVERAGE FLOW VELOCITY(FEET/SEC.) = 4.88
PRODUCT OF DEPTH&VELOCITY = 1.24
STREETFLOW TRAVELTIME(MIN) = 1.54 TC(MIN) = 13.20
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 3.381
•USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4 600
SUBAREA AREA(ACRES) = 0.63 SUBAREA RUNOFF(CFS) = 0.97
SUMMED AREA(ACRES) = 1.8 6 TOTAL RUNOFF(CFS) = 3.06
END OF SUBAREA STREETFLOW HYDRAULICS:
DEPTH(FEET) =0.27 HALFSTREET FLOODWIDTH(FEET) = 7.29
FLOW VELOCITY(FEET/SEC.) = 4.71 DEPTH*VELOCITY = 1.28
****************************************************************************
FLOW PROCESS FROM NODE 25.00 TO NODE 22.00 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 4.2 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 9.8
UPSTREAM NODE ELEVATION = 230.00
DOWNSTREAM NODE ELEVATION = 229.00
FLOWLENGTH(FEET) = 15.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1
PIPEFLOW THRU SUBAREA(CFS) = 3.06
TRAVEL TIME(MIN.) = 0.03 TC(MIN.) = 13.22
****************************************************************************
FLOW PROCESS FROM NODE 22.00 TO NODE 22.00 IS CODE = 1
»»>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE««<
TOTAL NUMBER OF STREAMS = 3
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:
TIME OF CONCENTRATION(MIN.) = 13.22
RAINFALL INTENSITY(INCH/HR) = 3.38
TOTAL STREAM AREA(ACRES) = 1.8 6
PEAK FLOW RATE(CFS) AT CONFLUENCE = 3.06
****************************************************************************
FLOW PROCESS FROM NODE 26.00 TO NODE 27.00 IS CODE = 21
>»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS««<
•USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .8700
INITIAL SUBAREA FLOW-LENGTH = 470.00
UPSTREAM ELEVATION = 304.00
DOWNSTREAM ELEVATION = 260.00
ELEVATION DIFFERENCE = 44.00
URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 4.259
•CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH
DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED.
TIME OF CONCENTRATION ASSUMED AS 6-MINUTES
50 YEAR RAINFALL INTENSITY{INCH/HOUR) = 5.622
SUBAREA RUNOFF(CFS) = 3.00
TOTAL AREA(ACRES) = 0.61 TOTAL RUNOFF(CFS) = 3.00
****************************************************************************
FLOW PROCESS FROM NODE 27.00 TO NODE 28.00 IS CODE = 6
»»>COMPUTE STREETFLOW TRAVELTIME THRU SUBAREA««<
UPSTREAM ELEVATION = 260.00 DOWNSTREAM ELEVATION = 230.00
STREET LENGTH(FEET) = 410.00 CURB HEIGHT(INCHES) = 6.
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK = 14.00
INTERIOR STREET CROSSFALL(DECIMAL) = 0.020
OUTSIDE STREET CROSSFALL(DECIMAL) =0.020
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
**TRAVELTIME COMPUTED USING MEAN FLOW(CFS) =3.78
STREETFLOW MODEL RESULTS:
STREET FLOWDEPTH(FEET) = 0.27
HALFSTREET FLOODWIDTH(FEET) = 7.29
AVERAGE FLOW VELOCITY(FEET/SEC.) = 5.82
PRODUCT OF DEPTH&VELOCITY = 1.58
STREETFLOW TRAVELTIME(MIN) = 1.18 TC(MIN) = 7.18
50 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.009
•USER SPECIFIED(SUBAREA):
SINGLE FAMILY DEVELOPMENT RUNOFF COEFFICIENT = .4 600
SUBAREA AREA(ACRES) = 0.67 SUBAREA RUNOFF(CFS) = 1.54
SUMMED AREA(ACRES) = 1.28 TOTAL RUNOFF(CFS) = 4.55
END OF SUBAREA STREETFLOW HYDRAULICS:
DEPTH(FEET) = 0.2 9 HALFSTREET FLOODWIDTH(FEET) = 8.18
FLOW VELOCITY(FEET/SEC.) = 5.78 DEPTH*VELOCITY = 1.67
****************************************************************************
FLOW PROCESS FROM NODE 28.00 TO NODE 22.00 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 6.8 INCHES
PIPEFLOW VELOCITY(FEET/SEC.) = 7.4
UPSTREAM NODE ELEVATION = 230.00
DOWNSTREAM NODE ELEVATION = 229.00
FLOWLENGTH(FEET) = 45.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES
PIPEFLOW THRU SUBAREA(CFS) = 4.55
TRAVEL TIME(MIN.) = 0.10 TC(MIN.) = 7.28
****************************************************************************
FLOW PROCESS FROM NODE 22.00 TO NODE 22.00 IS CODE = 1
»»>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE««<
»»>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES««<
TOTAL NUMBER OF STREAMS = 3
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 3 ARE:
TIME OF CONCENTRATION(MIN.) = 7.28
RAINFALL INTENSITY(INCH/HR) = 4.96
TOTAL STREAM AREA(ACRES) = 1.28
PEAK FLOW RATE(CFS) AT CONFLUENCE = 4.55
•• CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 10.04 15.78 3.012 9.18
2 3.06 13.22 3.377 1.86
3 4.55 7.28 4.964 1.28-
RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 3 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 12.72 7.28 4.964
2 15.10 13.22 3.377
3 15.52 15.78 3.012
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:
PEAK FLOW RATE(CFS) = 15.52 Tc(MIN.) = 15.78
TOTAL AREA(ACRES) = 12.32
+ +
I I
I END OF NORTHERN SUBAREA |
I i
+ +
END OF STUDY SUMMARY:
PEAK FLOW RATE(CFS) = 15.52 Tc(MIN.) = 15.78
TOTAL AREA(ACRES) = 12.32
END OF RATIONAL METHOD ANALYSIS
Hydrology Study
La Costa Greens- Planning Area 1.12
REFERENCE DATA
NOTE: Some reference data that has typically been included in support of hydrologic
calculations done by hand are incorporated into the Rational Method
Hydrology Computer Program Package (by AES). These include:
• Intensity-Duration Design Chart
• Nomograph for Determination of Time of Concentration (Tc) for
Natural Watersheds
• Urban Areas Overland Time of Flow Curves
• Runoff Coefficients (Rational Method)
Since these references are incorporated into the AES software, they
are not needed to support this study and are therefore not included in
this report.
Soils maps are also not included, as Hydrologic Soil Group "D" was
used for this study.
OA h:\repoiU\2352\049\a01 .doc
w.o, 2352-49 8/30/2002 1:38 PM