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Home My WebLink AboutW.O. 1375-74; Rancho Carrillo Village L-Horton; Rancho Carrillo Village L; 1999-04-15HUNSAKER ^ASSOCIATES SAN DIEGO, INC. PLANNING ENGINEERING SURVEYING IRVINE LAS VEGAS RIVERSIDE SAN DIEGO PRELIMINARY HYDROLOGY STUDY for RANCHO CARRILLO VILLAGE L City of San Diego, California Prepared for: D.R. Morton 1010 South Coast Highway 101 Suite 101 Encinitas, CA 92024 W.O. 1375-74 April 15, 1999 DAVE HAMMAR JACK HILL LEX WILLIMAN 10179 Huennekens St. Suite 200 San Diego, CA 92121 (619) 558-4500 PH (619) 558-1414 FX www. hunsaker.com lnfo@HunsakerSD.com Hunsaker & Associates San Diego, Inc. David A. Hammar, R.C.E. President ESM:kd msworO\k:\1375M999Wfl7.doc W.O. 1375-74 04/15/89 Rancho Carrillo - Village L Hydrology Study TABLE OF CONTENTS SECTION Executive Summary I Introduction I Summary of Results I References I Vicinity Map II Methodology & Model Development III Peak Flowrate Determination II! Hydrologic Analysis -100 Year Return Interval IV Reference Data V Hydrology Map (pocket) ESM:kd mswordUtA1375\1999WB7.doc W.0.1375-74 04/15/99 Rancho Carrillo - Village L Hydrology Study EXECUTIVE SUMMARY Introduction Village L of the Rancho Carrillo development is located east of Melrose Drive in the City of Carlsbad. The site, which has a drainage area of roughly 5 acres, will drain to an existing 18-inch RCP located on the northwest side of the development. All site runoff will be intercepted by a series of four curb inlets, two of which will be placed in roadway sag locations and the other two located in a flow by location. This hydrologic analysis determines the peak flowrates for the Village L development based on a 6-hour rainfall duration and a 100-year return interval. Methodology for the analysis appears in Section III, results appear in Section IV, and reference data such as rainfall nomographs and runoff coefficients appear in Section V. Inlet locations and existing pipe sizes appear on the hydrology map located in the pocket at the end of this report. Summary of Results Table 1 below summarizes the results of the hydrologic analysis. Curb inlets for this analysis will be designed to intercept 100 percent of the runoff. Table 1 - Hydrologic Results 100-Year Design Storm Inlet Node Number 103.0 115.5 107.0 113.0 Flow Condition Flow by Flow by Sump Sump 100-Year Peak Flow (cfs) 4.58 1.10 2.63 8.97 Drainage Area (acres) 1.20 0.29 0.70 2.70 ESM:kd msvmrtfJt\1375\199fl\dB7.doc W.O. 1375-74 04/15/99 Rancho Carrillo -Village L Hydrology Study Table 2 below summarizes the preliminary pipe sizing for the storm drain systems in the analysis. Final pipe sizes will be determined after a hydraulic analysis has been performed. All pipes are assumed to be RCP. Initial calculations show that a 24-inch RCP will convey the total runoff from the site to the existing pipe along the property's northwest boundary. Table 2 - Preliminary Pipe Sizing 100 Year Design Storm Upstream Node Number 103.0 115.5 107.0 113.0 200.0 ' Downstream Node Number 115.5 200.0 200.0 200.0 500.0 Pipe Size (inches) 18 18 18 18 24 100-Year Peak Flow (cfs) 4.58 5.61 2.63 8.79 16.37 Drainage Area (acres) 1.2 1.5 0.7 2.7 4.9 References 1. City of San Diego Drainage Design Manual, 1984. 2. County of San Diego Drainage Design & Procedure Manual, 1985. ESMikd msword\k:\1375\1999VJ87.(toc W.0.1375-74 Q4/1SS9 CITY OF OCEANSIOE PROJECT LOCATION CITY OF SAN MARCOS CITY OF ENC1N1TA5 RANCHO CARRILLO FIGURE 1 VICINITY MAP Ill Rancho Carrillo -Village L Hydrology Study METHODOLOGY & MODEL DEVELOPMENT Peak Flowrate Determination Design Storm 100-year return interval Land Use Mostly multi-family residential; some open space Soil Type Hydrologic soil group D Runoff Coefficient In accordance with County of San Diego standards, a runoff coefficient of 0.7 was selected for most areas and 0.45 for the recreational areas. Rainfall Intensity Initial time of concentration values were determined using the County of San Diego's overland flow nomograph for urban watersheds. Intensity values were derived from the County's 1985 Intensity-Duration nomograph. 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. In performing a node-link study, the total watershed area is divided into subareas which discharge at designated nodes. Subbasins are delineated based upon locations of inlets, ridge lines, confluences, etc. ESM:Hd mswortUcM 375\1999W87.DOC W.0.1375-74 04/15/99 Rancho Carrillo - Village L Hydrology Study The procedure for the Subarea Summation Model is as follows: (1) Subdivide the watershed into subareas with the initial subarea being less than 10 acres in size (generally 1 lot will do), and subsequent subareas gradually increasing in size. Assign upstream and downstream nodal numbers to each subarea to correlate calculations to the watershed map. (2) Estimate a Tc by using a nomograph or overland flow velocity estimation. (3) Using 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. The nodes are joined together by links, which may be street gutter flows, drainage swales or drainage ditches. The Computer subarea menu is as follows: Enter Upstream node number Enter Downstream node number SUBAREA HYDROLOGIC PROCESS 1. Confluence analysis at node. 2. Initial subarea analysis. 3. Pipeflow travel time (computer estimated). 4. Pipeflow travel time (user specified). 5. Trapezoidal channel travel time. 6. Street flow analysis through subarea. 7. User - specified information at node. 8. Addition of sub area runoff to main line. 9. V-gutter flow through area. Select subarea hydrologic process The engineer enters in the pertinent nodes, and then the hydrologic process. At the confluence point of two or more basins, the following procedure is used to adjust the total summation of peak flow rates to allow for differences in basin times of concentration. This adjustment is based on ESM:kd mswonj*:\l375\1999\da7.doc W.O. 1375-74 04/15/99 Rancho Carrillo - Village L Hydrology Study 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 (|a/]b); 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 of the T values. QP = Qb + Qa (Tt/Ta); Tp = Tb Underground storm drains are analyzed in a similar way. Flow data obtained from the surface model for inlets and collection points are input into the nodes representing those structures. Design grades and lengths are used to compute the capacity of the storm drains and to model the downstream travel times. ESM:WJ mswwO\k:\1375\1999W87.doc W.O. 1375-74 04H5/99 IV **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-93 Advanced Engineering Software (aes) Ver. 1.5A Release Date: 7/10/93 License ID 1239 Analysis prepared by: HUNSAKER & ASSOCIATES Irvine, Inc. Planning * Engineering * Surveying Three Hughes * Irvine , California 92718 * (714) 538-1010 ************************** DESCRIPTION OF STUDY ************************** * RANCHO CARRILLO VILLAGE "L" * * W0# 1375-74 * * 100 YEAR - 6 HOUR PRECIPITATION * ************************************************************************** FILE NAME: 1375\74\RC500.RAT TIME/DATE OF STUDY: 16: 7 4/ 8/1999 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: 1985 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100.00 6-HOUR DURATION PRECIPITATION (INCHES) = 2.900 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 114.00 TO NODE 114.50 IS CODE = 21 >»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<«« *USER SPECIFIED(SUBAREA): RURAL DEVELOPMENT RUNOFF COEFFICIENT = .6500 INITIAL SUBAREA FLOW-LENGTH = 90.00 UPSTREAM ELEVATION = 353.50 DOWNSTREAM ELEVATION = 352.00 ELEVATION DIFFERENCE = 1.50 URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 6.481 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.463 SUBAREA RUNOFF(CFS) = .38 TOTAL AREA(ACRES) = .09 TOTAL RUNOFF(CFS) = .38 **************************************************************************** FLOW PROCESS FROM NODE 115.00 TO NODE 115.50 IS CODE = 6 _____ — __ — _____ — — — — ____ — _. _ ___._.__,-i_.__--.--_.-._ --i — — — — — — — — — — — — — •-.— — __ — — -_. — — — _ — ._. — — — -..-._-. — .-•.-,_____. >»»COMPUTE STREETFLOW TRAVELTIME THRU SUBAREA<«« UPSTREAM ELEVATION = 353.00 DOWNSTREAM ELEVATION = 350.00 STREET LENGTH(FEET) = 200.00 CURB HEIGHT(INCHES) = 6. STREET HALFWIDTH(FEET) = 15.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK 7.50 INTERIOR STREET CROSSFALL(DECIMAL) = .020 OUTSIDE STREET CROSSFALL(DECIMAL) = .020 SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1 **TRAVELTIME COMPUTED USING MEAN FLOW(CFS) = .74 STREETFLOW MODEL RESULTS: STREET FLOWDEPTH(FEET) = .23 HALFSTREET FLOODWIDTH(FEET) = 5.30 AVERAGE FLOW VELOCITY (FEET/SEC.) = 1.86 PRODUCT OF DEPTH&VELOCITY = .43 STREETFLOW TRAVELTIME(MIN) = 1.79 TC(MIN) = 8.28 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.521 *USER SPECIFIED(SUBAREA): RURAL DEVELOPMENT RUNOFF COEFFICIENT = .6500 SUBAREA AREA(ACRES) = .20 SUBAREA RUNOFF(CFS) = .72 SUMMED AREA(ACRES) = .29 TOTAL RUNOFF(CFS) = 1.10 END OF SUBAREA STREETFLOW HYDRAULICS: DEPTH(FEET) = .25 HALFSTREET FLOODWIDTH(FEET) = 6.14 FLOW VELOCITY(FEET/SEC.) = 2.21 DEPTH*VELOCITY = .55 ************************************************************************* FLOW PROCESS FROM NODE 115.50 TO NODE 115.50 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.) = 8.28 RAINFALL INTENSITY(INCH/HR) = 5.52 TOTAL STREAM AREA(ACRES) = .29 PEAK FLOW RATE(CFS) AT CONFLUENCE = 1.10 **************************************************************** FLOW PROCESS FROM NODE 100.00 TO NODE 101.00 IS CODE = 21 >»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<«« SOIL CLASSIFICATION IS "D" MULTI-UNITS DEVELOPMENT RUNOFF COEFFICIENT = .7000 INITIAL SUBAREA FLOW-LENGTH = 115.00 UPSTREAM ELEVATION = 363.60 DOWNSTREAM ELEVATION = 362.20 ELEVATION DIFFERENCE = 1.40 URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 7.231 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.023 SUBAREA RUNOFF(CFS) = 1.26 TOTAL AREA(ACRES) - .30 TOTAL RUNOFF(CFS) = 1.26 ******************************************************* FLOW PROCESS FROM NODE 102.00 TO NODE 103.00 IS CODE = >»»COMPUTE STREETFLOW TRAVELTIME THRU SUBAREA<«« UPSTREAM ELEVATION = 358.00 DOWNSTREAM ELEVATION = 350.00 STREET LENGTH(FEET) = 340.00 CURB HEIGHT(INCHES) =6. STREET HALFWIDTK(FEET) = 15.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK = 7.50 INTERIOR STREET CROSSFALL(DECIMAL) = .020 OUTSIDE STREET CROSSFALL(DECIMAL) = .020 SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1 **TRAVELTIME COMPUTED USING MEAN FLOW(CFS) = 2.90 STREETFLOW MODEL RESULTS: STREET FLOWDEPTH(FEET) = .30 HALFSTREET FLOODWIDTH(FEET) = 8.67 AVERAGE FLOW VELOCITY(FEET/SEC.) = 3.34 PRODUCT OF DEPTH&VELOCITY = 1.00 STREETFLOW TRAVELTIME(MIN) = 1.70 TC(MIN) = 8.93 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.257 SOIL CLASSIFICATION IS "D" MULTI-UNITS DEVELOPMENT RUNOFF COEFFICIENT = .7000 SUBAREA AREA(ACRES) = .90 SUBAREA RUNOFF(CFS) = 3.31 SUMMED AREA(ACRES) = 1.20 TOTAL RUNOFF(CFS) = 4.58 END OF SUBAREA STREETFLOW HYDRAULICS: DEPTH(FEET) = .33 HALFSTREET FLOODWIDTH(FEET) = 10.36 FLOW VELOCITY(FEET/SEC.) = 3.84 DEPTH*VELOCITY = 1.28 ************************************************************ FLOW PROCESS FROM NODE 103.00 TO NODE 115.50 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 8.6 INCHES PIPEFLOW VELOCITY(FEET/SEC.) = 5.5 UPSTREAM NODE ELEVATION = 344.00 DOWNSTREAM NODE ELEVATION = 343.70 FLOWLENGTH(FEET) = 30.00 MANNING'S N = .013 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPEFLOW THRU SUBAREA(CFS) = 4.58 TRAVEL TIME(MIN.) = .09 TC(MIN.) = 9.02 **************************************************************************** FLOW PROCESS FROM NODE 115.50 TO NODE 115.50 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.) = 9.02 RAINFALL INTENSITY(INCH/HR) = 5.22 TOTAL STREAM AREA(ACRES) = 1.20 PEAK FLOW RATE(CFS) AT CONFLUENCE = 4.58 ** CONFLUENCE DATA ** STREAM RUNOFF Tc NUMBER (CFS) (MIN. 1 1.10 8.28 2 4.58 9.02 INTENSITY (INCH/HOUR) 5.521 5.223 AREA (ACRE) .29 1.20 — RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO CONFLUENCE FORMULA USED FOR 2 STREAMS. ** PEAK FLOW RATE TABLE ** STREAM RUNOFF Tc NUMBER (CFS) (MIN. 1 5.43 8.28 2 5.61 9.02 INTENSITY (INCH/HOUR) 5.521 5.223 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS PEAK FLOW RATE(CFS) = 5.61 Tc(MIN.) = TOTAL AREA(ACRES) = 1.49 9.02 ***************************************************************** FLOW PROCESS FROM NODE 115.50 TO NODE 200.00 IS CODE = >»»COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<«« »»>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW) ESTIMATED PIPE DIAMETER(INCH) INCREASED DEPTH OF FLOW IN 18.0 INCH PIPE IS 9 PIPEFLOW VELOCITY(FEET/SEC. UPSTREAM NODE ELEVATION = DOWNSTREAM NODE ELEVATION = FLOWLENGTH(FEET) = 200.00 5.8 343.70 341.70 MANNING'S ESTIMATED PIPE DIAMETER(INCH) = 18.00 PIPEFLOW THRU SUBAREA(CFS) = 5.61 TRAVEL TIME(MIN.) = .57 TC(MIN.) TO 18.000 7 INCHES N = .013 NUMBER OF PIPES 9.59 **************************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 200.00 IS CODE = 10 »»>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK # 1 ««< **************************************************************************** FLOW PROCESS FROM NODE 104.00 TO NODE 105.00 IS CODE = 21 >»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS«<« SOIL CLASSIFICATION IS "D" MULTI-UNITS DEVELOPMENT RUNOFF COEFFICIENT = .7000 INITIAL SUBAREA FLOW-LENGTH = 100.00 UPSTREAM ELEVATION = 350.20 DOWNSTREAM ELEVATION = 349.50 ELEVATION DIFFERENCE = .70 URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 8.109 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.594 SUBAREA RUNOFF(CFS) = 1.17 TOTAL AREA(ACRES) = .30 TOTAL RUNOFF(CFS) = 1.17 **************************************************************************** FLOW PROCESS FROM NODE 106.00 TO NODE 107.00 IS CODE = 6 >»»COMPUTE STREETFLOW TRAVELTIME THRU SUBAREA«<« - UPSTREAM ELEVATION = 349.00 DOWNSTREAM ELEVATION = 347.70 STREET LENGTH(FEET) = 130.00 CURB HEIGHT(INCHES) = 6. — STREET HALFWIDTH(FEET) = 15.00 "" DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK = 7.50 « INTERIOR STREET CROSSFALL(DECIMAL) = .020 OUTSIDE STREET CROSSFALL(DECIMAL) = .020 -«M SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1•m « **TRAVELTIME COMPUTED USING MEAN FLOW(CFS) = 1.90 STREETFLOW MODEL RESULTS: STREET FLOWDEPTH(FEET) = .30 m HALFSTREET FLOODWIDTH(FEET) = 8.67 AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.19 PRODUCT OF DEPTH&VELOCITY = .66 STREETFLOW TRAVELTIME(MIN) = .99 TC(MIN) = 9.10 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.193 *" SOIL CLASSIFICATION IS "D" M MULTI-UNITS DEVELOPMENT RUNOFF COEFFICIENT = .7000 SUBAREA AREA (ACRES) = .40 SUBAREA RUNOFF (CFS) = 1.45 - SUMMED AREA(ACRES) = .70 TOTAL RUNOFF(CFS) = 2.63 END OF SUBAREA STREETFLOW HYDRAULICS: "" DEPTH(FEET) = .33 HALFSTREET FLOODWIDTH(FEET) = 10.36 „. FLOW VELOCITY(FEET/SEC.) = 2.21 DEPTH*VELOCITY = .74 ************************** FLOW PROCESS FROM NODE 107.00 TO NODE 200.00 IS CODE = >»»COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<«« >»»USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW). ESTIMATED PIPE DIAMETER (INCH) INCREASED DEPTH OF FLOW IN 18.0 INCH PIPE IS 6 PIPEFLOW VELOCITY (FEET/SEC.) = 4.8 UPSTREAM NODE ELEVATION = 341.90 DOWNSTREAM NODE ELEVATION = 341.70 FLOWLENGTH(FEET) = 20.00 MANNING'S TO .3 N 18.000 INCHES = .013 ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPEFLOW THRU SUBAREA(CFS) = 2.63 TRAVEL TIME(MIN.) = .07 TC{MIN.) = 9.17 **************************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 200.00 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.) = 9.17 RAINFALL INTENSITY(INCH/HR) = 5.17 TOTAL STREAM AREA(ACRES) = .70 PEAK FLOW RATE(CFS) AT CONFLUENCE = 2.63 ************************************************************ FLOW PROCESS FROM NODE 110.00 TO NODE 111.00 IS CODE = 21 >»»RATIONAL METHOD INITIAL SUBAREA ANALYSIS<«« SOIL CLASSIFICATION IS "D" MULTI-UNITS DEVELOPMENT RUNOFF COEFFICIENT = .7000 INITIAL SUBAREA FLOW-LENGTH - 290.00 UPSTREAM ELEVATION = 366.00 DOWNSTREAM ELEVATION = 353.00 ELEVATION DIFFERENCE = 13.00 URBAN SUBAREA OVERLAND TIME OF FLOW(MINUTES) = 7.437 *CAUTION: SUBAREA SLOPE EXCEEDS COUNTY NOMOGRAPH DEFINITION. EXTRAPOLATION OF NOMOGRAPH USED. 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.915 SUBAREA RUNOFF(CFS) = 2.07 TOTAL AREA(ACRES) = .50 TOTAL RUNOFF{CFS) = 2.07 **************************************************************************** FLOW PROCESS FROM NODE 112.00 TO NODE 113.00 IS CODE = 6 >»»COMPUTE STREETFLOW TRAVELTIME THRU SUBAREA<«« UPSTREAM ELEVATION = 354.00 DOWNSTREAM ELEVATION - 347.70 STREET LENGTH(FEET) = 485.00 CURB HEIGHT(INCHES) = 6. STREET HALFWIDTH(FEET) = 15.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK = 7.50 INTERIOR STREET CROSSFALL(DECIMAL) = .020 OUTSIDE STREET CROSSFALL(DECIMAL) = .020 SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 2 **TRAVELTIME COMPUTED USING MEAN FLOW(CFS) = 5.01 STREETFLOW MODEL RESULTS: STREET FLOWDEPTH(FEET) = .32 HALFSTREET FLOODWIDTH(FEET) = 9.52 AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.45 PRODUCT OF DEPTH&VELOCITY = .77 STREETFLOW TRAVELTIME(MIN) = 3.31 TC(MIN) = 10.74 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.666 SOIL CLASSIFICATION IS "D" MULTI-UNITS DEVELOPMENT RUNOFF COEFFICIENT = .7000 SUBAREA AREA(ACRES) = 1.80 SUBAREA RUNOFF(CFS) = 5.88 SUMMED AREA(ACRES) = 2.30 TOTAL RUNOFF(CFS) = 7.95 END OF SUBAREA STREETFLOW HYDRAULICS: DEPTH(FEET) = .35 HALFSTREET FLOODWIDTH(FEET) = 11.20 FLOW VELOCITY(FEET/SEC.) = 2.89 DEPTH*VELOCITY - 1.01 FLOW PROCESS FROM NODE 116.00 TO NODE 117.00 IS CODE = >»»ADDITION OF SUBAREA TO MAINLINE PEAK FLOW««< ,, 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.666 *USER SPECIFIED(SUBAREA): — RURAL DEVELOPMENT RUNOFF COEFFICIENT = .4500 SUBAREA AREA(ACRES) = .20 SUBAREA RUNOFF(CFS) = .42 *" TOTAL AREA (ACRES) = 2.50 TOTAL RUNOFF (CFS) = 8.37 _ TC(MIN) = 10.74 urn ********************************************************** "* FLOW PROCESS FROM NODE 118.00 TO NODE 119.00 IS CODE = 8 *" >»»ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<«« *»_________________,__________._________..____.__._.__ = =: = = = = = = = = = = = — ==: = = = =; = = = = = = = = =: 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.666 - *USER SPECIFIED(SUBAREA): «. INDUSTRIAL DEVELOPMENT RUNOFF COEFFICIENT = .4500 SUBAREA AREA(ACRES) = .20 SUBAREA RUNOFF(CFS) = .42 - TOTAL AREA(ACRES) = 2.70 TOTAL RUNOFF(CFS) = 8.79 TC(MIN) = 10.74mm -••» **************************************************************************** - FLOW PROCESS FROM NODE 113.00 TO NODE 200.00 IS CODE = 3 *" >»»COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<«« ^ >»»USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW) ««< - DEPTH OF FLOW IN 18.0 INCH PIPE IS 13.1 INCHES PIPEFLOW VELOCITY(FEET/SEC.) = 6.4 "" UPSTREAM NODE ELEVATION = 341.80 _ DOWNSTREAM NODE ELEVATION = 341.70 FLOWLENGTH(FEET) = 10.00 MANNING'S N = .013 — ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPEFLOW THRU SUBAREA(CFS) = 8.79 ~ TRAVEL TIME(MIN.) = .03 TC(MIN.) = 10.77 _**************************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 200.00 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.) = 10.77 RAINFALL INTENSITY(INCH/HR) = 4.66 -. TOTAL STREAM AREA (ACRES) =2.70 PEAK FLOW RATE(CFS) AT CONFLUENCE = 8.79 WM ** CONFLUENCE DATA ** "" STREAM RUNOFF Tc INTENSITY AREA ~ NUMBER {CFS) (MIN.) (INCH/HOUR) (ACRE) 1 2.63 9.17 5.167 .70 2 8.79 10.77 4.658 2.70 - RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO « CONFLUENCE FORMULA USED FOR 2 STREAMS. ** PEAK FLOW RATE TABLE ** ^ STREAM RUNOFF Tc NUMBER (CFS) (MIN. ** 1 10.55 9.17 2 11.16 10.77 INTENSITY {INCH/HOUR) 5.167 4.658 <• COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS PEAK FLOW RATE(CFS) = 11.16 Tc(MIN.) = - TOTAL AREA (ACRES) = 3.40 10.77 ***************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 200.00 IS CODE = 11 >»»CONFLUENCE MEMORY BANK # 1 WITH THE MAIN-STREAM MEMORY<«« ** MAIN STREAM CONFLUENCE DATA ** STREAM RUNOFF Tc INTENSITY NUMBER (CFS) (MIN.) (INCH/HOUR) 1 11.16 10.77 4.658 ** MEMORY BANK # 1 CONFLUENCE DATA ** STREAM RUNOFF Tc INTENSITY NUMBER (CFS) (MIN.) (INCH/HOUR) 1 5.61 9.59 5.019 ** PEAK FLOW RATE TABLE ** STREAM RUNOFF Tc NUMBER (CFS) (MIN.) 1 15.97 9.59 2 16.37 10.77 INTENSITY (INCH/HOUR) 5.019 4.658 AREA (ACRE) 3.40 AREA (ACRE) 1.49 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS PEAK FLOW RATE(CFS) = 16.37 Tc(MIN.) = TOTAL AREA(ACRES) = 4.89 10.77 **************************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 200.00 IS CODE = 12 >»»CLEAR MEMORY BANK # 1 «<« ************************************************************ FLOW PROCESS FROM NODE 200.00 TO NODE 500.00 IS CODE = »»>COMPUTE PIPEFLOW TRAVELTIME THRU SUBAREA<«« »»>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW). DEPTH OF FLOW IN 24.0 INCH PIPE IS 15.7 INCHES PIPEFLOW VELOCITY(FEET/SEC.: UPSTREAM NODE ELEVATION = DOWNSTREAM NODE ELEVATION = FLOWLENGTH(FEET) = 130.00 7.5 341.70 340.40 MANNING'S ESTIMATED PIPE DIAMETER(INCH) = 24.00 PIPEFLOW THRU SUBAREA(CFS) = 16.37 TRAVEL TIME(MIN.) = .29 TCfMIN.) N = .013 NUMBER OF PIPES = 11.06 END OF STUDY SUMMARY: PEAK FLOW RATE(CFS) = 16.37 Tc(MIN.) = 11.06 TOTAL AREA(ACRES) = 4.89 END OF RATIONAL METHOD ANALYSIS V TABLE 2 P1 RUNOFF COEFFICIENTS (RATIONAL METHOD)-"^ L. DEVELOPED AREAS (URBAN) "* Land Use Coefficient. C • Soil Type (l)r** Residential: E) IT Single Family .55 Multi-Units .70 fc"• -. Mobile Homes . .65™> ^ Rural (lots greater than 1/2 acre) .45 . — Commercial (2) 80% Impervious ' .85 Industrial (2) 90% Impervious .95 NOTES: (.1) Type D soil to be used for all areas. (2) Where actual conditions deviate significantly from the tabulated imperviousness values of 80% or 90%T 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 soil. Actual imperviousness = 50% Tabulated imperviousness = 80% Revised C = |g- x 0.85 = 0.53 82 I I I I «•! •M ! l 1 ! I«•iiiiii T/M£ -tfifcT a/ fa/toff. C -.SO SAN DIEGO COUNTY DEPARTMENT OF SPECIAL DISTRICT SERVICES DESIGN MANUAL /-• ' V-/',- - ,r ( T:---- URBAN AREAS OVERLAND TIME OF FLOW CURVES fWiTF APPENDIX X-C i m i I CHART ! Equation: I • * 7.44 P, D "*645 4~ £ I « Intensity (In./Hr.) Pfi « 6 Hr. Precipitation (In.) D * Duration (Min.) lii 30 40 50 1 5 6 Directions for Application; 1) From precipitation naps determine 6 hr. and 24 hr. amounts for the selected frequency. These maps are printed 1n the County Hydrolon) Manual (10, 50 And 100 yr. maps included in tfr Design and Procedure Manual). 2) Adjust 6 hr. precipitation (if necessary) so that It 1s within the range of 452 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 theplotted lines. 5) This line 1s the intensity-duration curve for the location being analyzed. Application Form: 0) Selected Frequency 1) PC s Jn., P0| yr. 5S* 2) Adjusted *P6« 3) r - 24 In. m1n. 4) I In/hr. *Not Applicable to Desert Region APPENDIX XI IV-A-14 Rpvi if-d 1 CO, ..i'Y OF SAN DIEGO DEPARTMENT OF SANITATION FLOOD CONTROL 100-YEAR 6-HOUR PRECIPITATION ISOPLUVIALS PRECIPITATION IN OF 100-YEAR 6-HOUR terms or AM IKCII 33' U.S. DEPARTMEN NATIONAL OCEANIC AND AT SPECIAL STUDIES URANC1I, OFFICE OF II JSPHEHIC ADMINISTRATION >ROLOGV. NATIONAL WEATHER SERVICE I I I 1 Ii I i I I t i i i I i I i i i I i t j i i i i i Ln i I i t i I z:o S Ocr>;o 2 £r~ ^rn i—\^ 0 3? H > CO _~|> -<o •» oc:;a CD JOm.< O H -< O-?i A •^.*2 O moo i o n/I oz n om (/» — t zo -T- mr < r$ Io : Z £ ^ 5- a (AmobsH7-/i # |- u -^-^. — *• - tf -, ^^^ ^1 1 1 •*>Tr rM• i i i •v, /** H ^i a:1 i I • f 1 /* 1 11* ****• ^^A p* B^i iht^^ lL% iftl tf*V •* ^^HEIGHT OF OPENING in) IN FEET K» I* V t* o> "-j i» W o I ' K ' I • I'l'i'l'I'i'i.'L. tv* *j^ jk !_• fn ^_j «H MI r\ *-* M^ — * IV t^ ^^ * W VP ^^ fJP W ^J t"» --4- \ HEIGHT OF OPENING lh) IN INCHES \A*>V\* \ \ Vcx\_L \1-v- \ 0* «N x * 7A >•• *XT *?\ 3J I \ , ^^ CAPACITY PER FOOT OF LEN^HT OF OPEN WO (0/U IN CFS/FOQT j_ | ' i • | • | •[ MM'! " • -1""I •• "| • i • V | TI'IM ' ' "I'1"! ' "M ' 1 ¥ 1 ' I'lMM'l, O b D b b b — K> U j. bi Vta b» 5 w u^unoioOJw^wmoi \ j^ U \ l; \ \ *\X\ PONDED DEPTH IN TERMS OF HEIGHT OF OPENING (H/»)J -i-l- r-i n | i > r i | r ! i . | . i i . | I | • | t | i | • | i i < \ | I i I f | i | i | i ( — — N w * m K> u V ut <n '-g n to b u> — ..', ... • i i