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HomeMy WebLinkAboutCDP 2017-0023; 3913 SHERIDAN PLACE; DRAINAGE REPORT; 2017-08-30 (5)DRAINAGE REPORT 3913 SHERIDAN PLACE APN 206-042-47 CITY OF CARLSBAD PROJECT ID: CDP2017-0023 DRAWING NO: DWG 505-7A PERMIT NO: GR2017-0041 RECEIVED OCT l O 2017 LAND DEVELOPMENT ENGINEERING Prepared for: Prophet Solutions, Inc. 5845 Avenida Encinas, Suite 138 Carlsbad, CA 92008 Prepared by: b~A, Inc. land planning, civil engineering, surveying 5115 Avenida Encinas, Suite L Carlsbad, CA 92008-4387 (760) 931-8700 August 30, 2017 w.o. 1037-0810-600 TABLE OF CONTENTS Chapter 1-Discussion ....................................................................................................................................... 3 1.1 Vicinity Map .................................................................................................................................. 3 1.2 Purpose and Scope ........................................................................................................................ 4 1.3 Project Description ....................................................................................................................... 4 1.4 Pre-Development Conditions ...................................................................................................... 4 1.5 Post-Development Conditions ..................................................................................................... 5 1.6 Study Method ................................................................................................................................ 6 1.7 Conclusions .................................................................................................................................... 8 1.8 Declaration of Responsible Charge ............................................................................................ 9 Chapter 2 -Exhibits ......................................................................................................................................... 10 Existing Condition Hydrology Map ............................................................................................ 10 Developed Condition Hydrology Map ....................................................................................... 10 Chapter 3 -Hydrology Calculations ............................................................................................................... 12 3.1 Existing Condition Hydrology Calculations .............................................................................. 12 100-Year Storm ...................................................................................................................... 13 3.2 Developed Condition Hydrology Calculations ......................................................................... 15 100-Year Storm ...................................................................................................................... 16 2-Year Storm .......................................................................................................................... 20 Chapter 4 -Hydraulic Elements Calculations .............................................................................................. 25 Pipe Depth and Velocity ............................................................................................................. 25 Chapter 5 -References ..................................................................................................................................... 30 Methodology-Rational Method Peak Flow Determination ..................................................... 30 DRAiNAGE REpORT }91} S~rnidAN PlAcE, CARlsbAd, CA bl-tA, Inc. 2 CHAPTER 1 -DISCUSSION VICINITY MAP CITY OF' OCEANSIDE ~ or N MARCOS PACIFIC CITY or ENCINITAS DRAiNAGE REpORT }91} SlirnidAN PIACE, CARlsbAd, CA MiA, Inc. 1.2 PURPOSE AND SCOPE The purpose of this report is to publish the results of hydrology and hydraulic computer analysis for the proposed development of 3913 Sheridan Place, in the City of Carlsbad. The scope of this study is to analyze the results of existing and developed condition hydrology calculations and provide recommendations as to the design and size of various hydraulic and storm water conveyance systems. The mitigation measures proposed will include storm drains and catch basins to route runoff to the storm water conveyance system. The 100-year storm frequency will be analyzed for both pre-and post-development conditions. 1.3 PROJECT DESCRIPTION The project site is located at 3913 Sheridan Place in the City of Carlsbad (APN 206-042-47), within a developed residential cul-de-sac, south of Tamarack Avenue and west of Interstate 5 Freeway. The project property consists of a relatively level, nearly rectangular-shaped vacant parcel. The property consist of approximately 0.16 acres. The project site drains to one discharge location near the northwest corner of the project site. Per County of San Diego drainage criteria, the Modified Rational Method should be used to determine peak flowrates when the contributing drainage area is less than 1.0 square mile. All storm water quality requirements for the project will be met by the source control and site design BMPs (LID BMPs) intended to reduce the rate and volume of storm water runoff and associated pollutant loads. Please refer to the "Standard Project Requirement Checklist Form E-36" for low impact development strategies throughout the project. 1.4 PRE-DEVELOPMENT CONDITIONS The existing lot is characterized as a relatively level surface near the adjacent Sheridan Place street grades, which bounds the property along the eastern margin. Developed residential lots neighbour the property on the north, south and west sides. The property is covered with a thick growth of native grasses. Existing surface drainage at the site is not well-defined, however, neither ponded water nor excessively moist to wet ground surface conditions were noted at the time of field investigations. Drainage appears to sheet-flow northwest towards Sheridan Place. There are two storm drain inlets on Sheridan Place located west of the property. Underlying hydrologic soil is Type B as determined from NRCS Web Soil Survey (see Chapter 5 -References). Onsite soils areas have been assumed to be compacted in the existing condition to represent the current condition of the site. DRAiNAGE REpORT }91} ShrnidAN PIAcE, CARlsbAd, CA bl-tA, Inc. 4 The following table summarizes the existing condition runoff information from the site. Refer to the Existing Condition Hydrology Map for drainage patterns and areas. TABLE 1-Summary of Existing Condition Peak Flow: Discharge Location Drainage Area (Ac) 100-Year Peak Flow Time of (cfs) Concentration (min) Northwest Corner 0.16 0.21 9.26 1.5 POST-DEVELOPMENT CONDITIONS The project proposes the development of a single-family residence and a detached accessory dwelling unit with the associated structures and improvements. The structure is be constructed on the relatively level existing lot. The site will be approximately 58% impervious post-development. One point of discharge has been identified at the northwest corner of the project site on Sheridan Place. Prior to discharging from the project site, developed site runoff will be captured and conveyed by a series of yard drains and catch basins to the Sheridan Place curb and gutter system. Runoff from impervious areas such as rooftops and walkways will be directed onto the surface of adjacent pervious areas. The intent is to slow runoff discharges and reduce volumes while achieving incidental treatment. Proposed grading is minimized due to the previously level pad. Proposed drainage patterns will not alter the existing flow pattern and will discharge from the site at the historic discharge location. Table 2 summarizes the expected cumulative 100-year peak flow rate from the developed site. Refer to the Developed Condition Hydrology Map for drainage patterns and areas. TABLE 2-Summary of Developed Condition Peak Flow: Discharge Location Drainage Area (Ac) 100-Year Peak Flow Time of (cfs) Concentration (min) Northwest Corner 0.16 0.52 8.13 DRAiNAGE REpORT }9U SlirnidAN PIAcE, CARlsbAd, CA b~A, Inc. 1.6 STUDY METHOD The method of analysis was based on the Rational Method according to the San Diego County Hydrology Manual (June 2003). The Hydrology and Hydraulic Analysis were done on Hydro Soft by Advanced Engineering Software 2013. The study considers the runoff for a 100-year storm frequency for both existing and proposed conditions. Methodology used for the computation of design rainfall events, runoff coefficients, and rainfall intensity values are consistent with criteria set forth in the "2003 County of San Diego Drainage Design Manual." A more detailed explanation of methodology used for this analysis is listed in Chapter 5 -References of this report. Drainage basin areas were determined from the topography and proposed grades shown on the Grading Plan for this site and County of San Diego 200-Scale Topography Maps. The Rational Method for this project provided the following variable coefficients: Rainfall Intensity -Initial time of concentration (Tc) values based on Table 3-2 of the San Diego County Hydrology Manual. Rainfall Isopluvial Maps from the County Hydrology Manual were used to determine P6 for 100-year storm, see References. RickRat Hydro was used to perform Rational Method hydrographs. The design storm pattern is based on the County of San Diego Intensity-Duration Design Chart. The chart uses the following equation to relate the intensity (I) of the storm to the time of concentration (Tc): Rainfall Intensity= I = 7.44x(P6)x(Tc)-0·645 P6 for 100-year storm =2.61" Soil Type -The site was modeled with Type B hydrologic soil as determined from the NRCS Web Soil Survey. Type B soils have moderate infiltration rates when thoroughly wetted. Runoff Coefficient -In accordance with the County of San Diego standards, runoff coefficients were based on land use and soil type. The soil conditions used in this study are consistent with Type B soil qualities. An appropriate runoff coefficient (C) for each type of land use in the subarea was selected from Table 3-1 of SD HM and multiplied by the percentage of total area (A) included in that class. The sum of the products for all land uses is the weighted runoff coefficient (2,[CA]). For all of the landscape areas, a runoff coefficient assuming 0% impervious was used based on the under-lying soil type, 0.25 for Type B soils. All decomposed granite areas were DRAiNAGE REpORT }9U ShrnidAN PIAcE, CARlsbAd, CA bl-tA, Inc. b assumed to be semi-pervious and assigned a runoff coefficient of 0.40. All roof, driveway and concrete sidewalk areas were considered 95 % impervious, and assigned a runoff coefficient of 0.87. Table 3 below summarizes the composite C-values calculated in the existing and proposed conditions. TABLE 3-Weighted Runoff Coefficient Calculations: Existing Hvdroloe:v Up Node Down Total C1 A1 (ac) C2 A2 (ac) C3 A3 (ac) Ccomp Node Area (ac) 1 3 0.16 0.25 0.16 0.40 0.00 0.87 0.00 0.25 Proposed Hvdrolo~" Up Node Down Total C1 Ai(ac) C2 A2 (ac) C3 A3 (ac) Ccomp Node Area (ac) 10 11 0.04 0.25 0.003 0.40 0.006 0.87 0.030 0.75 12 12 0.02 0.25 0.013 0.40 0.000 0.87 0.008 0.48 14 14 0.05 0.25 0.014 0.40 0.007 0.87 0.026 0.62 15 16 0.03 0.25 0.002 0.40 0.013 0.87 0.010 0.58 16 16 0.02 0.25 0.004 0.40 0.000 0.87 0.018 0.75 Note: (1) C-values taken from Table 3-1 of San Diego County Hydrology Manual, consistent with on-site existing soi I types. See References . (2) A1 equals total pervious surfaces, e.g. landscape. (3) A2 equals total semi-pervious surfaces, e.g. decomposed granite. (4) A3 equals total impervious surfaces, e.g. roof, concrete driveway, concrete sidewalks. All storm drain systems have been designed in accordance with the City of Carlsbad General Design Standards (Volume 1). The design of storm drain pipes shall be governed by a minimum permissible velocity of 2 fps in a 2-year frequency storm event. This design method assumes that a storm drain pipe will be self-cleaning and prevents deposits of silt. Chapter 4 of this report includes pipe depth and velocity calculations for the proposed storm drain system in the 2-year storm event. DRAiNA(iE REpORT }91} ShrnidAN PIAcE, CARlsbAd, CA bl-tA, Inc. 7 1.7 CONCLUSION Table 4 below summarizes the existing and developed condition drainage areas and resultant 100-year peak flow rates at the discharge location from the project site. TABLE 4-Summary of 100-Year Peak Flows: Drainage Area 100-Year Peak Flow Time of (acres) (cfs) Concentration (min) Pre-Developed Condition 0.16 0.21 9.26 Post-Developed Condition 0.16 0.52 8.13 DIFFERENCE 0.00 0.31 -1.13 As shown in the above table, the development of the proposed Sheridan Place project site will result in a net increase of peak flow discharged from the project site by approximately 0.31 cfs. However, the design of pervious areas to effectively receive, infiltrate and retain runoff from impervious surfaces will further mitigate runoff discharges and reduce volumes. Landscape areas are interspersed among the building and pavement areas to detain and retain runoff near the point where it is generated. These small collection techniques foster opportunities to maintain the natural hydrology and provide a much greater range of retention and detention practices. The developed site will also implement source control and site design BMPs in accordance with the site specific "Standard Project Requirement Checklist Form E-36". Peak flow rates listed above were generated based on criteria set forth in "San Diego County Hydrology Manual" ( methodology presented in Chapter 5 of this report). Rational method output is located in Chapter 3. The hydraulic calculations show that the proposed storm drain facilities can sufficiently convey the anticipated 0100 flowrate without any adverse effects. Furthermore, the storm drain pipes have been designed for a non-silting velocity of 2 fps in a 2-year frequency storm event. Based on this conclusion, runoff released from the proposed project site will be unlikely to cause any adverse impact to downstream water bodies or existing habitat integrity. Sediment will likely be reduced upon site development. DRAiNAGE REpORT J9U SlirnidAN PIACE, CARlsbAd, CA bliA, Inc. 8 1.8 DECLARATION OF RESPONSIBLE CHARGE I hereby declare that I am the Engineer of Work for this project, that I have exercised responsible charge over the design of the project as defined in section 6703 of the business and professions code, and that the design is consistent with current standards. I understand that the check of project drawings and specifications by the County of San Diego is confined to a review only and does not relieve me, as Engineer of Work, of my responsibilities for project design. Ronald Holloway I Date R.C.E. 29271 DRAiNAGE REpORT }91} SlirnidAN PlAcE, CARlsbAd, CA bl-tA, Inc. 9 DRAiNAGE REpORT CHAPTER2 EXHIBITS Existing Condition Hydrology Map & Developed Condition Hydrology Map }91} ShrnidAN PIAcE, CARlsbAd, CA bl-tA, Inc. 10 L EXISTING CONDITION HYDROLOGY MAP 3913 SHERIDAN PLACE, CITY OF CARLSJJAD °' w C-e- I , EXISTING 8" PVC \ WATERLINE PER DWG, 403-8 \N ~ \N ~ \N ---------\N ~ SHERIDAN PLACE ~ N1 3+38.30 EXISTING 1" WATER LATERAL PER D WG, 403-8 CL CTR CUL -DE-SAC EXISTING 2" FORCE I MAIN LATERAL PER DWG 403-8 / ' ~~ /'1/· ·, \ ,, -----;-----;----:,==='=c=-cc.=-.=;,~~~~'=F=--=··=·'-=· ======~;=====r~========:!===-==c--,·9'.~".0·· ~ . ~/ CCN1C. · en ·· EXISTING CONC. / . cii :; I .• I SIDEWALK ~-~===±=~~=======c====~~~~=w3~±i:~=====:=c'--~---= 0.21 7 BUILDING 206-042-26 J 7 BUILDING \ \ \ \ \ \ . \ I \ f \ @ C=0.25 \ \ \ \ \ \ \ J 111111 1111111 -------· ·-.• • 1111111 -1i1i1111 K:\Civil 3D\0810\DWG\HYDR0\1037-0810-EX HYDRO.dwg, 8/30/2017 1:45:43 PM EXISTING BUILDING BUILDING PROJECT BOUNDARY I. I L \ \ \ '@ \ C=0.25 \ \ GATE /\ LOT 15 I EXISTING BUILDING MAP NO. 14626 .• i PROJE T BOUND RY ~x1siJ SHED .L J LOT 5 1 O' 5' EXISTING BUILDING EXISTING BUILDING :>; ·.-. • •--,' ✓ o' 10· 20· SCALE: 1" = 10' LOT 12 MAP NO \;>' : . :_<·; ·'.: _, £> : ; I,, ·)\?: £> LOT 13 30' LEGEND SURFACE NODE SURFACE FLOW, 100 YEAR BASIN AREA RUNOFF COEFFICIENT BASIN BOUNDARY BASIN SUB-BOUNDARY PROJECT BOUNDARY FLOWLINE @0 C=0.25 mwrw . 0% ■-IBIIIIIIIIIIIIII-Mallillll PROJECT CHARACTERISTICS PARCEL AREA 0.16 ACRES APN 206-042-47 SOIL TYPE B DEPTH TO GROUNDWATER > 20 FEET SUMMARY OF EXISTING CONDITION PEAK FLOW DRAINAGE AREA (AC) 100-YEAR PEAK FLOW TIME OF DISCHARGE LOCATION {CFS) CONCENTRATION (IVIIN) NORTHWEST CORNER 0.16 0,21 9,26 WEIGHTED RUNOFF COEFFICIENT CALCULATIONS: Existing Hydrology Up Node Down Node Total Area {ac} c, A1 (ac) c, A,(ac) (3 A, (ac) Cwrn□ 1 3 0,16 0.25 . 0,16 0,4 0,00 0.87 -· 0,00 0,25 Note: (1) C-va I ues taken from Ta b!e 3-1 of San Di ego County Hydro! ogy Manual, cons[ stent with on-site existing soi I types. See References. (2) A1 equals total pervious surfaces. (3) A2 equals total semi-pervious surfaces. (4) A3 equals total impervious surfaces. b~A,lnc. lanol planning, cMI enginee~ng, surveying 5115 AVENIDA ENCINAS SUITE "L" CARLSBAD, CA. 92008-4387 (760) 931-8700 EXISTING CONDITION HYDROLOGY MAP 3913 SHERIDAN PLACE CITY OF CARLSBAD -------w 7 1" WATER S[RV/C[ CONNECTION SAWCUT/R[MOV[ ~ AND REPLACE AC " PVMT. ~ SHERIDAN PLACE /" WA T[R S[RV/C[ WITH M[T[R P[R CCSD W-'3 49 OJ FS 48. 33 /[ 2 ~ 4" PVC/3" REDUCERS 2 ~ 4" PVC @ 04% 49.12 TG 48.37 I[ @ DEVELOPED CONDITION HYDROLOGY MAP 3913 SHERIDAN PLACE, CITY OF CARL$BAD EXISTING 1" WATER LATERAL PER OWG. 403-8 49 83 FS 50.00 FS MAP NO. 14626 LOT 5 RIGHT-OF-WAY )( . '1,/ROUGr:Jl TR □i\l FENCE:/·· 49.58 -FS PROJEjT BOUND~RY EXISTING FENCE TO 8[ REMOVED EXISTING BUILDING L 49.19 FS 48.41 i[ 1111---'l-++-'--IIC=0.60 GARAGE I I 49.36 FG 48.62 IE 8' PUBLIC UTILITY [AS[M[NT P[R MAP NO. 4751 BUILDING J 7 BUILDING J K:\Civil 3D\0810\DWG\HYDR0\1037-0810-PROP HYDRO.dwg, 8/23/2017 3:13:32 PM ---------· ---- 206-042-26 I EXISTING~ BUILDING BUILDING 49.34 FS EXISTING FENG[ TO 8[ REMOVED 49.53 rs 49.62 FS 49.56 rs 48.63 I[ 4947 TG 48.65 IE PROJECT BOUNDARY LOT 16 (§) C=0.48 ·111111111 __ _ 2-STEPS 49.40 FS 2-STEPS 49.44 FS 50.20 FS OUTDOOR SHOWER I I I {CONNECT TO SEWER) ,IMA __ }N ~UILO/NG 6.25' 50.50 ff . 1111 50. oo· ,o AD ----._ -- (§) C=0.75 50.33 TG d8.67 /E \5033 TG 48.71 IE ACCESSORY BLDG 50.50 FF . <§}). C=0.58 MAP NO. 4757 "" GJ I . ' 'V 'V 'V • <§ C=0.75 • • " ' 50.J TG '" 48:91 !["\ [i)--+ SD ~+ 50.37 TG I 0.70 ,,._, ,·, 'Y.5 ' LOT 75 8' PUBLIC UTILITY [ASEM[NT .OER MAP NO. 4751 EXISTING BUILDING 49.63 TG 48. 71 /[ • > -:.··: ,•)~+,,,--.- 2+59.53 49.78 rs s 4" eve S[W[R LA T[RAL WI TH SEWER CLEAN OUT PER S-6 LOT 12 EXISTING BUILDING N28"39'00''W 108.14' y 0 _1 en /; I SAWCUT/REMOV[ 5' WIDE .OR/VA TE '0 "' AND R[PCAC[. SEWER EASEMENT .O[R CONCRETE DOC. 2016-073360 R[CORDfO 2/19/16 10' 5' ~ LOT 13 o' 10· 20' l~~~~~iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiaii F rr r SCALE: 1" = 10' 30' I I ' .'.'il 1+5( S[V✓t PER LEGEND i SURFACE NODE ;; SURFACE FLOW, 100 YEAR -. BASIN AREA RUNOFF COEFFICIENT ROOF AREA CONCRETE LANDSCAPING DECOMPOSED GRANITE BASIN BOUNDARY BASIN SUB-BOUNDARY PROJECT BOUNDARY FLOWL/NE @) C=0,61 ■-------■ PROJECT CHARACTERISTICS PARCEL AREA 0.16 ACRES APN 206-042-47 SOIL TYPE B DEPTH TO GROUNDWATER > 20 FEET SUMMARY OF DEVELOPED CONDITIONS PEAK FLOW DRAINAGE AREA {AC) 100-YEAR PEAK FLOW TIME OF DISCHARGE LOCATION (CFS) CONCENTRATION (MIN) NORTHWEST CORNER 0.16 0.49 8.87 WEIGHTED RUNOFF COEFFICIENT CALCULATIONS: Proposed Hydrology Up Node Down Node Total Area (ac} c, A, (ac) c, A, (ac) c, A, (ac) 10 11 0.04 0.25 0.003 0.40 0.006 0.87 0.030 12 12 0.02 0.25 0.013 0.40 0.000 0.87 0.008 14 14 0.05 0.25 0.014 0.40 0.007 0.87 0.026 15 16 0.03 0.25 0.002 0.40 0.013 0.87 0.010 16 16 0.02 0,25 0.004 0.40 0.000 0.87 0.018 C::r:,mp 0.75 0.48 0.62 0.58 0.75 Note: (1) C-va I ues ta ken from Table 3-1 of San Diego County Hydro I ogy Manual, consistent with on-site existing soi I types. See References. [2) A1 equals total pervious surfaces, e.g. landscape. (3) A2 equals total semi-pervious surfaces, e.g. decomposed granite. ( 4) A3 equa Is total impervious surfaces, e.g. roof, concrete driveway, concrete si dew·a I ks . bJ.t~lnc. land planning, cMI engineering, suiVelflng 5115 AVENIDA ENCINAS SUITE "L" CARLSBAD, CA. 92008-4387 (760) 931-8700 DEVELOPED CONDITION HYDROLOGY MAP 3913 S~IERIDAN PLACE CITY OF CARLSBAD ------------------CHAPTER3 --HYDROLOGY CALCULATIONS -3.1 -Existing Condition Hydrology Calculations .. -----.. -.. .. -... --.. 0RAiNAGE REpORT .. -:___:}:.._91::}...:S:::li.:.:ER:::id::.A:.:N_:P_:lA:..:.:c:.:E~, C=A:..:.:R.:.:ls:.:b:.:..:A~d,:._C.:.:A_:_ ___________________ b_~_A.;,_, _ln_c_. ____, 12 ------------------.. -.. .. - .. .. .. • .. 100-YEAR STORM **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-2012 Advanced Engineering Software (aes) Ver. 19.0 Release Date: 06/01/2012 License ID 1459 Analysis prepared by: BHA Inc 5115 Avenida Encinas, Suite L Carlsbad CA 92008 ************************** DESCRIPTION OF STUDY************************** * Existing Condition Hydrology Analysis * 100-Year Storm Frequency * 3913 Sheridan Place ************************************************************************** FILE NAME: 0810E100.DAT TIME/DATE OF STUDY: 11:30 03/31/2017 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: 2003 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100.00 6-HOUR DURATION PRECIPITATION (INCHES) = 2.610 SPECIFIED MINIMUM PIPE SIZE(INCH) = 3.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE= 0.95 SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD NOTE: USE MODIFIED RATIONAL METHOD PROCEDURES FOR CONFLUENCE ANALYSIS *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREET FLOW MODEL* * * * HALF-CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSS FALL IN-I OUT-/PARK-HEIGHT WIDTH LIP NO. (FT) (FT) SIDE I SIDE/ WAY (FT) (FT) (FT) --------------------------====== ====== 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 1. Relative Flow-Depth= 0.00 FEET as (Maximum Allowable Street Flow Depth) -(Top-of-Curb) 2. (Depth)*(Velocity) Constraint= 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* HIKE FACTOR (FT) (n) ======= 0.167 0.0150 **************************************************************************** FLOW PROCESS FROM NODE 1.00 TO NODE 2.00 IS CODE= 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .2500 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 30.00 UPSTREAM ELEVATION(FEET) = 50.49 DOWNSTREAM ELEVATION(FEET) = 50.17 ELEVATION DIFFERENCE(FEET) = 0.32 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.202 DRAiNAGE REpORT }91} SlirnidAN PIAcE, CARlsbAd, CA ---------bl-IA, Inc. "J ------------------------ -----------.. • 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.997 SUBAREA RUNOFF(CFS) 0.06 TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) 0.06 **************************************************************************** FLOW PROCESS FROM NODE 2.00 TO NODE 2.00 IS CODE= >>>>>USER SPECIFIED HYDROLOGY INFORMATION AT NODE<<<<< USER-SPECIFIED VALUES ARE AS FOLLOWS: TC(MIN) = 7.00 RAIN INTENSITY(INCH/HOUR) = 5.54 TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) = 0.10 7 **************************************************************************** FLOW PROCESS FROM NODE 2.00 TO NODE 3.00 IS CODE= 51 >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 50.17 DOWNSTREAM(FEET) CHANNEL LENGTH THRU SUBAREA(FEET) = 80.00 CHANNEL SLOPE CHANNEL BASE(FEET) 5.00 "Z" FACTOR= 10.000 MANNING'S FACTOR= 0.040 MAXIMUM DEPTH(FEET) = 1.00 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.622 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .2500 S.C.S. CURVE NUMBER (AMC II) = 0 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) AVERAGE FLOW DEPTH(FEET) 0.05 TRAVEL TIME(MIN.) 0.16 0.59 Tc(MIN.) = 9.26 0.11 SUBAREA AREA(ACRES) AREA-AVERAGE RUNOFF COEFFICIENT TOTAL AREA(ACRES) = 0.2 SUBAREA RUNOFF(CFS) 0.285 PEAK FLOW RATE(CFS) END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0.06 FLOW VELOCITY(FEET/SEC.) 2.26 49.03 0.0142 0.13 0.21 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 0.65 3.00 = 110.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) PEAK FLOW RATE(CFS) 0. 2 TC (MIN. ) = 0.21 END OF RATIONAL METHOD ANALYSIS DRAiNAGE REpORT }91} SlirnidAN P~cE, CARlsbAd, CA 9.26 bl-IA, Inc. 14 - ---------.. ---.. .. .. • --- - ---.. .. - CHAPTER3 HYDROLOGY CALCULATIONS 3.2 -Developed Condition Hydrology Calculations DRAiNAGE REpORT }91} S1-trnidAN PIAcE, CARlsbAd, CA bl-IA, Inc. ----.. ----------- • • -----.. -• .. ----• -• 100-YEAR STORM **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-2012 Advanced Engineering Software (aes) Ver. 19.0 Release Date: 06/01/2012 License ID 1459 Analysis prepared by: BHA Inc 5115 Avenida Encinas, Suite L Carlsbad CA 92008 ************************** DESCRIPTION OF STUDY************************** * Developed Condition Hydrology Analysis * 100 Year Storm Frequency * 3913 Sheridan Place ************************************************************************** FILE NAME: 0810Pl00.DAT TIME/DATE OF STUDY: 08:44 08/22/2017 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: 2003 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100.00 6-HOUR DURATION PRECIPITATION (INCHES) = 2.610 SPECIFIED MINIMUM PIPE SIZE(INCH) = 3.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE= 0.95 SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD NOTE: USE MODIFIED RATIONAL METHOD PROCEDURES FOR CONFLUENCE ANALYSIS *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREET FLOW MODEL* * * * HALF-CROWN TO STREET-CROSS FALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSS FALL IN-I OUT-/PARK-HEIGHT WIDTH LIP NO. (FT) (FT) SIDE I SIDE/ WAY (FT) (FT) (FT) --------------------------====== ====== 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0313 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 1. Relative Flow-Depth= 0.00 FEET as (Maximum Allowable Street Flow Depth) -(Top-of-Curb) 2. (Depth)*(Velocity) Constraint= 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* HIKE FACTOR (FT) (n) ======= 0.167 0.0150 **************************************************************************** FLOW PROCESS FROM NODE 10.00 TO NODE 11.00 IS CODE= 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .7500 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 57.00 UPSTREAM ELEVATION(FEET) = 50.04 DOWNSTREAM ELEVATION(FEET) = 49.63 ELEVATION DIFFERENCE(FEET) = 0.41 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 5.308 DRAiNAGE REpORT }91} S~rnidAN PlAcE, CARlsbAd, CA bl-tA, Inc. J ---------16 -----------------• -• -------.. -- - • --.. • 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.616 SUBAREA RUNOFF(CFS) 0.20 TOTAL AREA(ACRES) = 0.04 TOTAL RUNOFF(CFS) 0.20 **************************************************************************** FLOW PROCESS FROM NODE 11. 00 TO NODE 12.00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) FLOW LENGTH(FEET) = 43.80 ASSUME FULL-FLOWING PIPELINE 48.71 DOWNSTREAM(FEET) MANNING'S N = 0.009 PIPE-FLOW VELOCITY(FEET/SEC.) 2.27 PIPE FLOW VELOCITY= (TOTAL FLOW)/(PIPE CROSS SECTION AREA) GIVEN PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES 1 PIPE-FLOW(CFS) = 0.20 0.32 48.53 PIPE TRAVEL TIME(MIN.) = LONGEST FLOWPATH FROM NODE Tc (MIN.) = 10.00 TO NODE 5.63 12.00 100.80 FEET. **************************************************************************** FLOW PROCESS FROM NODE 12.00 TO NODE 12.00 IS CODE= 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.370 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .4800 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT= 0.6600 SUBAREA AREA(ACRES) 0.02 SUBAREA RUNOFF(CFS) TOTAL AREA(ACRES) = 0.1 TOTAL RUNOFF(CFS) = TC(MIN.) = 5.63 0.06 0.25 **************************************************************************** FLOW PROCESS FROM NODE 12.00 TO NODE 13.00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) FLOW LENGTH(FEET) = 37.33 48.53 DOWNSTREAM(FEET) MANNING'S N = 0.009 ASSUME FULL-FLOWING PIPELINE PIPE-FLOW VELOCITY(FEET/SEC.) 2.89 PIPE FLOW VELOCITY= (TOTAL FLOW)/(PIPE CROSS SECTION GIVEN PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES PIPE-FLOW(CFS) = 0.25 PIPE TRAVEL TIME(MIN.) = 0.22 Tc(MIN.) = AREA) 1 48.37 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 5.84 13. 00 138.13 FEET. **************************************************************************** FLOW PROCESS FROM NODE 13.00 TO NODE 13.00 IS CODE= 10 >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK# 1 <<<<< **************************************************************************** FLOW PROCESS FROM NODE 15.00 TO NODE 16.00 IS CODE= 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): DRAiNAGE REpORT J9U SlirnidAN P~cE, CARlsbAd, CA bl-tA, Inc. 17 -- ---... • ---------------------• ---- --• USER-SPECIFIED RUNOFF COEFFICIENT= .5800 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.50 UPSTREAM ELEVATION(FEET) = 50.04 DOWNSTREAM ELEVATION(FEET) = 49.47 ELEVATION DIFFERENCE(FEET) = 0.57 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 100 YEAR RAINFALL INTENSITY(INCH/HOUR) SUBAREA RUNOFF(CFS) 0.09 7.426 5.328 TOTAL AREA(ACRES) = 0.03 TOTAL RUNOFF(CFS) 0.09 **************************************************************************** FLOW PROCESS FROM NODE 16.00 TO NODE 16.00 IS CODE= 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.328 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .7500 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT= 0.6480 SUBAREA AREA(ACRES) 0.02 SUBAREA RUNOFF(CFS) TOTAL AREA(ACRES) = 0.0 TOTAL RUNOFF(CFS) = TC(MIN.) = 7.43 0.08 0.17 **************************************************************************** FLOW PROCESS FROM NODE 16.00 TO NODE 13.00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) FLOW LENGTH(FEET) = 65.13 ASSUME FULL-FLOWING PIPELINE 48.63 DOWNSTREAM(FEET) MANNING'S N = 0.009 PIPE-FLOW VELOCITY(FEET/SEC.) 1.98 PIPE FLOW VELOCITY= (TOTAL FLOW)/(PIPE CROSS SECTION GIVEN PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES PIPE-FLOW(CFS) = 0.17 PIPE TRAVEL TIME(MIN.) = 0.55 LONGEST FLOWPATH FROM NODE Tc (MIN.) = 15.00 TO NODE 7.98 13.00 AREA) 1 48.37 125.63 FEET. **************************************************************************** FLOW PROCESS FROM NODE 13.00 TO NODE 13.00 IS CODE= 11 >>>>>CONFLUENCE MEMORY BANK# 1 WITH THE MAIN-STREAM MEMORY<<<<< ** MAIN STREAM NUMBER 1 STREAM CONFLUENCE DATA** RUNOFF Tc INTENSITY (CFS) (MIN.) (INCH/HOUR) 0.17 7.98 5.089 LONGEST FLOWPATH FROM NODE 15.00 TO NODE ** MEMORY BANK# 1 CONFLUENCE DATA ** STREAM RUNOFF Tc INTENSITY NUMBER (CFS) (MIN.) ( INCH/HOUR) 1 0.25 5.84 6.218 LONGEST FLOWPATH FROM NODE 10.00 TO NODE ** PEAK FLOW RATE TABLE** STREAM RUNOFF Tc INTENSITY NUMBER (CFS) (MIN.) ( INCH/HOUR) DRAiNAGE REpORT J9U Sl-trnidAN P~cE, CARlsbAd, CA AREA (ACRE) 0.05 13.00 AREA (ACRE) 0.06 13.00 125.63 FEET . 138.13 FEET. bl-IA, Inc. 18 L -----• ------ ------• -----• - ---------• 1 2 0.38 0.38 5.84 7. 98 6.218 5.089 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) 0.38 Tc(MIN.) = TOTAL AREA(ACRES) = 0.1 7.98 **************************************************************************** FLOW PROCESS FROM NODE 13.00 TO NODE 14.00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) FLOW LENGTH(FEET) = 11.00 ASSUME FULL-FLOWING PIPELINE 48.37 DOWNSTREAM(FEET) MANNING'S N = 0.009 PIPE-FLOW VELOCITY(FEET/SEC.) 2.17 PIPE FLOW VELOCITY= (TOTAL FLOW)/(PIPE CROSS SECTION AREA) GIVEN PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES 2 PIPE-FLOW(CFS) = 0.38 0.08 48.33 PIPE TRAVEL TIME(MIN.) = LONGEST FLOWPATH FROM NODE Tc (MIN.) = 10.00 TO NODE 8.06 14.00 149.13 FEET. **************************************************************************** FLOW PROCESS FROM NODE 14.00 TO NODE 15.00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) FLOW LENGTH(FEET) = 10.00 ASSUME FULL-FLOWING PIPELINE 48.33 DOWNSTREAM(FEET) MANNING'S N = 0.009 PIPE-FLOW VELOCITY(FEET/SEC.) 3.86 PIPE FLOW VELOCITY= (TOTAL FLOW)/(PIPE CROSS SECTION AREA) GIVEN PIPE DIAMETER(INCH) = 3.00 NUMBER OF PIPES 2 PIPE-FLOW(CFS) = 0.38 48.13 PIPE TRAVEL TIME(MIN.) = 0.04 LONGEST FLOWPATH FROM NODE Tc (MIN.) = 10.00 TO NODE 8.10 15.00 159.13 FEET. **************************************************************************** FLOW PROCESS FROM NODE 15.00 TO NODE 15.00 IS CODE= 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.037 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .6200 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT= 0.6437 SUBAREA AREA(ACRES) 0.05 SUBAREA RUNOFF(CFS) TOTAL AREA(ACRES) = 0.2 TOTAL RUNOFF(CFS) = TC(MIN.) = 8.10 END OF STUDY SUMMARY: TOTAL AREA(ACRES) PEAK FLOW RATE(CFS) 0. 2 TC (MIN. ) = 0.52 END OF RATIONAL METHOD ANALYSIS DRAiNAGE REpORT }91} S~rnidAN PIAcE, CARlsbAd, CA 8.10 0.16 0.52 bl-IA, Inc. 19 L - ---• ------------• -------------.. 2-YEAR STORM **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-2013 Advanced Engineering Software (aes) Ver. 20.0 Release Date: 06/01/2013 License ID 1459 Analysis prepared by: BHA Inc 5115 Avenida Encinas, Suite L Carlsbad CA 92008 ************************** DESCRIPTION OF STUDY************************** * Developed Condition Hydrology Analysis * 2 Year Storm Frequency * 3913 Sheridan Place ************************************************************************** FILE NAME: 0810Pl00.DAT TIME/DATE OF STUDY: 08:37 08/30/2017 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: 2003 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) 2.00 6-HOUR DURATION PRECIPITATION (INCHES) = 1.120 SPECIFIED MINIMUM PIPE SIZE(INCH) = 3.00 SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE= 0.95 SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD NOTE: USE MODIFIED RATIONAL METHOD PROCEDURES FOR CONFLUENCE ANALYSIS *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREET FLOW MODEL* * * * HALF-CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSS FALL IN-I OUT-/PARK-HEIGHT WIDTH LIP NO. (FT) (FT) SIDE I SIDE/ WAY (FT) (FT) (FT) --------------------------====== ====== 1 30.0 20.0 0.018/0.018/0.020 0. 67 2.00 0.0312 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 1. Relative Flow-Depth= 0.00 FEET as (Maximum Allowable Street Flow Depth) -(Top-of-Curb) 2. (Depth)*(Velocity) Constraint= 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* HIKE FACTOR (FT) (n) ======= 0.167 0.0150 **************************************************************************** FLOW PROCESS FROM NODE 10.00 TO NODE 11.00 IS CODE= 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .7500 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 57.00 UPSTREAM ELEVATION(FEET) = 50.04 DOWNSTREAM ELEVATION(FEET) = 49.63 ELEVATION DIFFERENCE(FEET) = 0.41 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 5.308 DRAiNAGE REpORT }91} SkrnidAN P~cE, CARlsbAd, CA bliA, Inc. 20 L -• -----• - -------.. -.. -----.. -------- 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.839 SUBAREA RUNOFF(CFS) 0.09 TOTAL AREA(ACRES) = 0.04 TOTAL RUNOFF(CFS) 0.09 **************************************************************************** FLOW PROCESS FROM NODE 11. 00 TO NODE 11. 00 IS CODE = 7 >>>>>USER SPECIFIED HYDROLOGY INFORMATION AT NODE<<<<< USER-SPECIFIED VALUES ARE AS FOLLOWS: TC(MIN) = 5.31 RAIN INTENSITY(INCH/HOUR) = 2.84 TOTAL AREA(ACRES) = 0.04 TOTAL RUNOFF(CFS) = 0.10 **************************************************************************** FLOW PROCESS FROM NODE 11. 00 TO NODE 12.00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 48.71 DOWNSTREAM(FEET) FLOW LENGTH(FEET) = 43.80 MANNING'S N = 0.009 DEPTH OF FLOW IN 4.0 INCH PIPE IS 2.3 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 1.97 GIVEN PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES 1 PIPE-FLOW(CFS) = 0.10 0.37 Tc(MIN.) = 48.53 PIPE TRAVEL TIME(MIN.) = LONGEST FLOWPATH FROM NODE 10.00 TO NODE 5.68 12.00 100.80 FEET. **************************************************************************** FLOW PROCESS FROM NODE 12.00 TO NODE 12.00 IS CODE= 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.719 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .4800 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT= 0.7470 SUBAREA AREA(ACRES) 0.02 SUBAREA RUNOFF(CFS) TOTAL AREA(ACRES) = 0.1 TOTAL RUNOFF(CFS) = TC(MIN.) = 5.68 0.03 0.12 **************************************************************************** FLOW PROCESS FROM NODE 12.00 TO NODE 13.00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 48.53 DOWNSTREAM(FEET) FLOW LENGTH(FEET) = 37.33 MANNING'S N = 0.009 DEPTH OF FLOW IN 4.0 INCH PIPE IS 2.4 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 2.24 GIVEN PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES 1 PIPE-FLOW(CFS) = 0.12 0.28 48.37 PIPE TRAVEL TIME(MIN.) = LONGEST FLOWPATH FROM NODE Tc (MIN.) = 10.00 TO NODE 5.96 13.00 138.13 FEET. **************************************************************************** FLOW PROCESS FROM NODE 13. 00 TO NODE 13.00 IS CODE= 10 >>>>>MAIN-STREAM MEMORY COPIED ONTO MEMORY BANK# 1 <<<<< DRAiNAGE REpORT }91} SliERidAN PmcE, CARlsbAd, CA bl-iA, Inc. 21 L -------.. • ------------------------.. -- **************************************************************************** FLOW PROCESS FROM NODE 15.00 TO NODE 16.00 IS CODE= 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .5800 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = UPSTREAM ELEVATION(FEET) = 50.04 DOWNSTREAM ELEVATION(FEET) = 49.47 ELEVATION DIFFERENCE(FEET) = 0.57 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 2 YEAR RAINFALL INTENSITY(INCH/HOUR) SUBAREA RUNOFF(CFS) 0.04 60.50 7.426 2.286 TOTAL AREA(ACRES) = 0.03 TOTAL RUNOFF(CFS) 0.04 **************************************************************************** FLOW PROCESS FROM NODE 16.00 TO NODE 16.00 IS CODE= 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.286 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .7500 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF SUBAREA AREA(ACRES) TOTAL AREA(ACRES) = TC(MIN.) = 7.43 COEFFICIENT= 0.6480 0.02 SUBAREA RUNOFF(CFS) 0.0 TOTAL RUNOFF(CFS) = 0.03 0.07 **************************************************************************** FLOW PROCESS FROM NODE 16.00 TO NODE 16.00 IS CODE= 7 >>>>>USER SPECIFIED HYDROLOGY INFORMATION AT NODE<<<<< USER-SPECIFIED VALUES ARE AS FOLLOWS: TC(MIN) = 7.43 RAIN INTENSITY(INCH/HOUR) = 2.29 TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) = 0.10 **************************************************************************** FLOW PROCESS FROM NODE 16.00 TO NODE 13.00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 48.63 DOWNSTREAM(FEET) FLOW LENGTH(FEET) = 65.13 MANNING'S N = 0.009 DEPTH OF FLOW IN 4.0 INCH PIPE IS 2.3 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 1.97 GIVEN PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES 1 PIPE-FLOW(CFS) = 0.10 48.37 PIPE TRAVEL TIME(MIN.) = 0.55 LONGEST FLOWPATH FROM NODE Tc (MIN.) = 15.00 TO NODE 7.98 13.00 125.63 FEET. **************************************************************************** FLOW PROCESS FROM NODE 13.00 TO NODE 13.00 IS CODE= 11 >>>>>CONFLUENCE MEMORY BANK# 1 WITH THE MAIN-STREAM MEMORY<<<<< DRAiNAGE REpORT }91} SlirnidAN P~cE, CARlsbAd, CA bl-iA, Inc. 22 ------• -----------.. ------.. .. -.. .. -- ** MAIN STREAM CONFLUENCE DATA** STREAM RUNOFF Tc INTENSITY AREA NUMBER (CFS) (MIN.) ( INCH/HOUR) (ACRE) 1 0.10 7.98 2.183 0.05 LONGEST FLOWPATH FROM NODE 15.00 TO NODE 13.00 125.63 FEET. ** MEMORY BANK# 1 CONFLUENCE DATA** STREAM RUNOFF Tc INTENSITY AREA NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE) 1 0.12 5.96 2. 636 0.06 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 13.00 138 .13 FEET. ** PEAK FLOW RATE TABLE** STREAM RUNOFF Tc INTENSITY NUMBER (CFS) (MIN.) ( INCH/HOUR) 1 0.20 5. 96 2.636 2 0.20 7. 98 2.183 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) 0.20 Tc(MIN.) = 7.98 TOTAL AREA(ACRES) = 0.1 **************************************************************************** FLOW PROCESS FROM NODE 13.00 TO NODE 14.00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 48.37 DOWNSTREAM(FEET) FLOW LENGTH(FEET) = 11.00 MANNING'S N = 0.009 DEPTH OF FLOW IN 4.0 INCH PIPE IS 2.3 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 1.98 GIVEN PIPE DIAMETER(INCH) = 4.00 NUMBER OF PIPES 2 PIPE-FLOW(CFS) = 0.20 48.33 PIPE TRAVEL TIME(MIN.) = 0.09 LONGEST FLOWPATH FROM NODE Tc (MIN.) = 10.00 TO NODE 8.07 14.00 149.13 FEET. **************************************************************************** FLOW PROCESS FROM NODE 14.00 TO NODE 15.00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 48.33 DOWNSTREAM(FEET) FLOW LENGTH(FEET) = 10.00 MANNING'S N = 0.009 DEPTH OF FLOW IN 3.0 INCH PIPE IS 1.6 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 3.82 GIVEN PIPE DIAMETER(INCH) = 3.00 NUMBER OF PIPES 2 PIPE-FLOW(CFS) = 0.20 48 .13 PIPE TRAVEL TIME(MIN.) = 0.04 LONGEST FLOWPATH FROM NODE Tc (MIN.) = 10.00 TO NODE 8.12 15.00 159.13 FEET. **************************************************************************** FLOW PROCESS FROM NODE 15.00 TO NODE 15.00 IS CODE= 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 2 YEAR RAINFALL INTENSITY(INCH/HOUR) = 2.159 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .6200 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT= 0.7473 DRAiNAGE REpORT }91} SltrnidAN PIAcE, CARlsbAd, CA bl-IA, Inc. L ------- ---------------- -.. .. --.. .. • -.. .. .. SUBAREA AREA(ACRES) TOTAL AREA(ACRES) = TC(MIN.) = 8.12 END OF STUDY SUMMARY: TOTAL AREA(ACRES) PEAK FLOW RATE(CFS) 0.05 SUBAREA RUNOFF(CFS) = 0.2 TOTAL RUNOFF(CFS) = 0. 2 TC (MIN. ) = 0.26 8.12 END OF RATIONAL METHOD ANALYSIS DRAiNAGE REpORT }91} ShrnidAN PIAcE, CARlsbAd, CA 0.07 0.26 bl-tA, Inc. 24 -• • ---• -• ----------------- - -• .. CHAPTER4 HYDRAULIC ELEMENTS CALCULATIONS Pipe Depth and Velocity DRAiNAGE REpORT }91} Sl-irnidAN PlAcE, CARlsbAd, CA bliA, Inc. -----·--·--·,··----·~~---~---·~•~--------.................................................. .! ---• • • -• --------------- -- -• - 2-YEAR STORM **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-2012 Advanced Engineering Software (aes) Ver. 19.0 Release Date: 06/01/2012 License ID 1459 Analysis prepared by: BHA Inc 5115 Avenida Encinas, Suite L Carlsbad CA 92008 ************************** DESCRIPTION OF STUDY************************** * Pipe Depth and Velocity * 2 Year Storm Frequency * 3913 Sheridan Place ************************************************************************** NODEll-12 TIME/DATE OF STUDY: 09:49 08/30/2017 Problem Descriptions: Node 11 -12 Pipe Depth and Velocity (1) 4" PVC Storm Drain Pipe * * * **************************************************************************** >>>>PIPEFLOW HYDRAULIC INPUT INFORMATION<<<< PIPE DIAMETER(FEET) = 0.333 PIPE SLOPE(FEET/FEET) = 0.0040 PIPEFLOW(CFS) = 0.10 MANNINGS FRICTION FACTOR= 0.009000 CRITICAL-DEPTH FLOW INFORMATION: CRITICAL DEPTH(FEET) = 0.18 CRITICAL FLOW AREA(SQUARE FEET) = 0.047 CRITICAL FLOW TOP-WIDTH(FEET) = 0.332 CRITICAL FLOW PRESSURE+ MOMENTUM(POUNDS) = 0.41 CRITICAL FLOW VELOCITY(FEET/SEC.) = 2.132 CRITICAL FLOW VELOCITY HEAD(FEET) = 0.07 CRITICAL FLOW HYDRAULIC DEPTH(FEET) 0.14 CRITICAL FLOW SPECIFIC ENERGY(FEET) 0.25 NORMAL-DEPTH FLOW INFORMATION: NORMAL DEPTH(FEET) = 0.18 FLOW AREA(SQUARE FEET) = 0.05 FLOW TOP-WIDTH(FEET) = 0.332 FLOW PRESSURE+ MOMENTUM(POUNDS) FLOW VELOCITY(FEET/SEC.) FLOW VELOCITY HEAD(FEET) = HYDRAULIC DEPTH(FEET) = 0.15 FROUDE NUMBER= 0.950 SPECIFIC ENERGY(FEET) = DRAiNAGE REpORT }91} SlirnidAN PIAcE, CARlsbAd, CA ------- 2.062 0.066 0.25 0.40 bl-tA, Inc. 26 .. • ---------- ------- - --- - - - .. • NODE 12-13 TIME/DATE OF STUDY: 09:59 08/30/2017 Problem Descriptions: Node 12 -13 Pipe Depth and Velocity (1) 4" PVC Storm Drain Pipe **************************************************************************** >>>>PIPEFLOW HYDRAULIC INPUT INFORMATION<<<< PIPE DIAMETER(FEET) = 0.333 PIPE SLOPE(FEET/FEET) = 0.0040 PIPEFLOW(CFS) = 0.12 MANNINGS FRICTION FACTOR= 0.009000 CRITICAL-DEPTH FLOW INFORMATION: CRITICAL DEPTH(FEET) = 0.19 CRITICAL FLOW AREA(SQUARE FEET) = 0.053 CRITICAL FLOW TOP-WIDTH(FEET) = 0.328 CRITICAL FLOW PRESSURE+ MOMENTUM(POUNDS) = 0.53 CRITICAL FLOW VELOCITY(FEET/SEC.) = 2.275 CRITICAL FLOW VELOCITY HEAD(FEET) = 0.08 CRITICAL FLOW HYDRAULIC DEPTH(FEET) 0.16 CRITICAL FLOW SPECIFIC ENERGY(FEET) 0.27 NORMAL-DEPTH FLOW INFORMATION: NORMAL DEPTH(FEET) = 0.20 FLOW AREA(SQUARE FEET) = 0.06 FLOW TOP-WIDTH(FEET) = 0.325 FLOW PRESSURE+ MOMENTUM(POUNDS) FLOW VELOCITY(FEET/SEC.) FLOW VELOCITY HEAD(FEET) = HYDRAULIC DEPTH(FEET) = 0.17 FROUDE NUMBER= 0.913 SPECIFIC ENERGY(FEET) = NODE16-13 TIME/DATE OF STUDY: 10:01 08/30/2017 Problem Descriptions: Node 16 -13 Pipe Depth and Velocity 2.149 0.072 0.28 0.50 (1) 4" PVC Storm Drain Pipe **************************************************************************** >>>>PIPEFLOW HYDRAULIC INPUT INFORMATION<<<< PIPE DIAMETER(FEET) = 0.333 PIPE SLOPE(FEET/FEET) = 0.0040 PIPEFLOW(CFS) = 0.10 MANNINGS FRICTION FACTOR= 0.009000 CRITICAL-DEPTH FLOW INFORMATION: CRITICAL DEPTH(FEET) = 0.18 CRITICAL FLOW AREA(SQUARE FEET) 0.047 DRAiNAGE REpORT }91} ShrnidAN P~cE, CARlsbAd, CA bl-IA, Inc. 27 L ------------------ • -----------• ------ CRITICAL FLOW TOP-WIDTH (FEET) = 0.332 CRITICAL FLOW PRESSURE+ MOMENTUM(POUNDS) CRITICAL FLOW VELOCITY(FEET/SEC.) = 2.132 CRITICAL FLOW VELOCITY HEAD(FEET) = CRITICAL FLOW HYDRAULIC DEPTH(FEET) CRITICAL FLOW SPECIFIC ENERGY(FEET) NORMAL-DEPTH FLOW INFORMATION: NORMAL DEPTH(FEET) = 0.18 FLOW AREA(SQUARE FEET) = 0.05 FLOW TOP-WIDTH(FEET) = 0.332 FLOW PRESSURE+ MOMENTUM(POUNDS) FLOW VELOCITY(FEET/SEC.) FLOW VELOCITY HEAD(FEET) = HYDRAULIC DEPTH(FEET) = 0.15 FROUDE NUMBER= 0.950 SPECIFIC ENERGY(FEET) = NODE13-14 TIME/DATE OF STUDY: 10:03 08/30/2017 Problem Descriptions: Node 13 -14 Pipe Depth and Velocity (1) 4" PVC Storm Drain Pipe 2.062 0.066 0.25 0.07 0.14 0.25 0.40 0.41 **************************************************************************** >>>>PIPEFLOW HYDRAULIC INPUT INFORMATION<<<< PIPE DIAMETER(FEET) = 0.333 PIPE SLOPE(FEET/FEET) = 0.0040 PIPEFLOW(CFS) = 0.20 MANNINGS FRICTION FACTOR= 0.009000 CRITICAL-DEPTH FLOW INFORMATION: CRITICAL DEPTH(FEET) = 0.25 CRITICAL FLOW AREA(SQUARE FEET) = 0.071 CRITICAL FLOW TOP-WIDTH(FEET) = 0.285 CRITICAL FLOW PRESSURE+ MOMENTUM(POUNDS) = 1.10 CRITICAL FLOW VELOCITY(FEET/SEC.) = 2.826 CRITICAL FLOW VELOCITY HEAD(FEET) = 0.12 CRITICAL FLOW HYDRAULIC DEPTH(FEET) 0.25 CRITICAL FLOW SPECIFIC ENERGY(FEET) 0.38 ==>NORMAL PIPEFLOW IS PRESSURE FLOW NODE14-15 TIME/DATE OF STUDY: 10:08 08/30/2017 Problem Descriptions: Node 14 -15 Pipe Depth and Velocity (2) 3" PVC Storm Drain Pipes **************************************************************************** DRAiNAGE REpORT }91} SkrnidAN PIAcE, CARlsbAd, CA bl-tA, Inc. 28 L ----------- -------• ---------- ------• >>>>PIPEFLOW HYDRAULIC INPUT INFORMATION<<<< PIPE DIAMETER(FEET) = 0.250 PIPE SLOPE(FEET/FEET) = 0.0200 PIPEFLOW(CFS) = 0.10 MANNINGS FRICTION FACTOR= 0.009000 CRITICAL-DEPTH FLOW INFORMATION: CRITICAL DEPTH(FEET) = 0.19 CRITICAL FLOW AREA(SQUARE FEET) = 0.040 CRITICAL FLOW TOP-WIDTH(FEET) = 0.212 CRITICAL FLOW PRESSURE+ MOMENTUM(POUNDS) = 0.48 CRITICAL FLOW VELOCITY(FEET/SEC.) = 2.478 CRITICAL FLOW VELOCITY HEAD(FEET) = 0.10 CRITICAL FLOW HYDRAULIC DEPTH(FEET) 0.19 CRITICAL FLOW SPECIFIC ENERGY(FEET) 0.29 NORMAL-DEPTH FLOW INFORMATION: NORMAL DEPTH(FEET) = 0.13 FLOW AREA(SQUARE FEET) = 0.03 FLOW TOP-WIDTH(FEET) = 0.250 FLOW PRESSURE+ MOMENTUM(POUNDS) 0.73 FLOW VELOCITY(FEET/SEC.) 3.772 FLOW VELOCITY HEAD(FEET) = 0.221 HYDRAULIC DEPTH(FEET) = 0.11 FROUDE NUMBER= 2.039 SPECIFIC ENERGY(FEET) = 0.35 DRAiNAGE REpORT }91} S~rnidAN PIACE, CARlsbAd, CA bl-tA, Inc. 29 L ----- -• ----------CHAPTERS --REFERENCES --Methodology -Rational Method Peak Flow Determination -------- • • --DRAiNAGE REpORT }91} S~rnidAN PIAcE, CARlsbAd, CA bl-IA, Inc. - ---------• -----.. - --- ---- • - .. -• -- - NOAA Atlas 14, Volume 6, Version 2 Location name: Carlsbad, California, USA* Latitude: 33.1501°, Longitude: -117.3392° Elevation: 50.91 ft** • source: ESRI Maps .. source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Sarah Dietz, Sarah Heim, Lillian Hiner, Kazungu Maitaria, Deborah Martin, Sandra Pavlovic, lshani Roy, Cart Trypaluk, Dale Unruh, Fenglin Yan, Michael Yekta, Tan Zhao, Geoffrey Bonnin, Daniel Brewer, Li-Chuan Chen, Tye Parzybok, John Yarchoan NOAA, National Weather Service, Silver Spring, Maryland PF tabular I PF graphical I Maps & aerials PF tabular I PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 jouratlonll Avera9e recurrence Interval !y:ears) 1 II 2 II 5 II 10 II 25 II 50 II 100 II 200 II 500 II 1000 5-min •-•~~ ~~1•-~· 0.418 0.476 0.560 0.630 0.110-0.157) 0.139-0.199) 0.286-0.471) (0.319-0.554 (0.353-0.649) 0.397-0.798) (0.430-0.932) 10-min 0.18 0.524 0.600 0.683 (0.5~:~1 3 -~~:34) (0.158-0 0.410-0.675) (0.458-0.794 (0.506-0.9311 15-min 0.227 0.288 0.634 0.725 0.825 0.971 1.09 (0.191-0.273 0.242-0.346 "' 0.496-0.817 IC0.554-0.960' C0.611-1.13) 10.688-1.38) co. 7 46-1.62) 130-min I 0.322 0.408 0.526 0.629 0.776 0.897 1.03 1.17 1.38 1.55 (0.271-0.387) (0.342-0.490 0.441-0.634) (0.522-0.764 (0.622-0.979) (0.703-1.16) (0. 784-1.36) (0.866-1.60) (0.974-1.96) (1.06-2.29) 60-min 0.435 0.550 0.710 0.848 1.05 1.21 1.39 1.58 1.86 2.09 (0.366-0.522) (0.462-0.661) 0.595-0.856) (0.705-1.03) (0.840-1.32) (0.949-1.56) (1.06-1.84) (1.17-2.15) (1.32-2.65) (1.43-3.09) 2-hr 0.588 0.733 0.934 1.11 1.35 1.56 1.77 2.01 2.35 2.63 0.495-0.705) (0.616-0.881) (0.783-1.13) (0.918-1.35) (1.08-1.71) (1.22-2.01) (1.35-2.34) (1.49-2. 74) (1.66-3.35) (1.80-3.89) I I I 3-hr 0.691 0.860 1.09 I (1.01-;~~57) 11 (1.2~~?.98) 11 (1.4~-~~32) 11 (1.5~~:71) 11 (1.7~-~~-15) 11 (1.9~·!:.83) 11 (2.0~~:.44) I 0.582-0.830 10.723-1.03) (0.915-1.32) B 0.894 I 1.12 II 1.42 II 1.67 I 2.03 I (1.8~-~;.98) 11 (1.~~!t6) 11 (2.1~~:.99) 11 (2.3!~:.81) 11 (2.5~?:.53) I (0.752-1.07) : (0.938-1.34) :: (1.19-1.71) :: (1.39-2.03): (1.63-2.56) 8 1.13 1.43 1.84 2.17 2.63 2.99 3.36 3.74 4.26 4.67 (0.949-1.35) (1.21-1.72) (1.54-2.22) (1.81-2.64) (2.11-3.32) (2.34-3.85) (2.56-4.44) (2. 77-5.10) (3.02-6.07) (3.19-6.91) 8 1.38 1.79 2.32 2.75 3.34 3.79 4.24 4.71 5.34 5.83 (1.21-1.59) (1.58-2.07) (2.04-2.70) (2.40-3.22) (2.82-4.03) (3.14-4.66) (3.43-5.34) (3.71-6.09) (4.05-7.18) (4.28-8.10) I 2-c1ay II (1.4~-!~95) II (1.!~~55) II (2.5~-~i34) II (2.9~~00) II (3.5~·~:.02) II (3.9~·?:.82) II (4.2~-~~67) II (4.~·~:.61) II (5.o~!:.99) II (5.Je·~~0.1) I I 3-c1ay II (1.6~~:.18) II (2.1~~:.86) II (2.8!·~:.76) II (3.3~~:.52) II (3.9~?~.69) II (4.4~·~:.61) II (4.8~·~;60) II (5.2~?:.69) II (5.ici!~.3) II (6.1~~~1.6) I ~ 2.04 2.69 3.54 4.23 5.17 5.90 6.65 7.41 8.46 9.27 (1.80-2.37) (2.37-3.11) (3.11-4.11) (3.69-4.95) (4.37-6.25) (4.89-7.27) (5.38-8.37) (5.85-9.59) (6.41-11.4) (6.80-12.9) J 7-day I 2.37 3.14 4.16 5.00 6.15 7.05 7.96 8.92 10.2 11.2 (2.09-2.74) (2.77-3.64) (3.66-4.83) (4.36-5.85) (5.20-7.43) (5.84-8.68) (6.45-10.0) (7 .03-11.5) (7.75-13.8) (8.25-15.6) ~ 2.63 3.50 4.66 5.62 6.95 7.99 9.06 10.2 11.7 12.9 (2.32-3.04) (3.08-4.05) (4.10-5.41) (4.90-6.58) (5.88-8.39) (6.62-9.84) (7.33-11.4) (8.02-13.2) (8.88-15.8) (9.48-18.0) I 2o-c1ay II (2.8;~:.69) II (3.7!~:.98) II (5.o~·?;,72) II (6.1~~:24) I 8.80 I 10.2 II 11.6 I 13.2 15.3 I (121~-~3.6) I (7.43-10.6) : (8.44-12.5) :: (9.42-14.7) : (10.4-17.0) (11.6-20.6) I 30-day I (3.33:3?:.37) 5.10 6.91 8.44 10.6 I 12.3 I 14.2 16.1 18.8 21.0 (4.49-5.91) (6.07-8.03) (7.36-9.88) (8.97-12.8) : (10.2-15.2) : 111.5-17.8) (12.7-20.8) (14.3-25.3) (15.4-29.2) 145-day 1 4.46 6.02 8.18 10.0 12.7 14.8 17.1 19.5 23.0 25.8 (3.93-5.16) (5.30-6.97) (7.19-9.50) (8.74-11.7) (10.7-15.3) (12.3-18.2) (13.8-21.5) (15.4-25.2) (17.4-30.9) (18.9-35.8) 160-day I 5.15 6.92 9.40 11.5 14.6 17.1 19.8 22.7 26.9 30.4 (4.54-5.96) (6.10-8.02) (8.26-10.9) (10.1-13.5) (12.4-17.6) (14.2-21.1) (16.1-25.0) (17.9-29.4) (20.4-36.3) (22.3-42.3) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information . Back to Top 30 1 25 .I:. 0. QI 20 "O C: ~ 15 ~ 'i5.. ·u £ 10 s 0 C: -~ Ill 35 30 ~ 25 .i::. .w 0. QI 20 "O PF graphical PDS-based depth-duration-frequency (DDF) curves Latitude: 33.1501~. Longitude: -117.3392° . . . . . . . . . , . • • • v<o • • • ~ a¥¥ v • J. v • ""• • -'• • v • • )' • • , ~ • • v, • .) , v • • • ,>, • , • • • '> • • , Y • \ • , .+, , . .) , , • • ,j • w ••• Y Y • • ••• Y A -> • ., • . . . . , . . . . . . ' . . . . . . . . . , . ' . . . . , • • • • > • • , • • > • ' • . . . . . . . . , . . • ,, <· .,,,,.: ...• , •. } . , ••• ,:v •• ,.,. ~-'"i· .. ,. {· ..... ,,;.,, ,. ,.,,. :,.-.•. ·} .. ··~--~·· -•·:---!-. --• <· -· . . , . . . . . ·• . . . . , . • • > • > • ' > ' > • • • ,. • • • > • ' > • ~ • • • • ., , • ' • • ' • • < • • • • • • • • • < > < > > ! > ~ \ • I t ' f . ·--:•. -·=-· .... f • ..... ~--· ..... -:• ... -; ··-••• ~·· •• ·•!--·. --: ..... -:--<---:-♦ ~ •·:-• -:-•••• -:♦ -. . , . . . . ' . . . . , ' . • • • • • , • • > •• ' < • • , , • • > • • , < ' , < • • , , , . , . ' ' ' , , . ' . < < ' < ' , • ' • • ~ ' > • , • , • , > • ' • • ~ ' • ' • y ¥ "(' • ., ¥ (' • , ., • ' .. ¥ ¥ • • • 1,., • • ¥ • 'l>' • V '<,' • • • • -,. ¥ • • + -•.r • • • ¥ •,, • _., • • • J ~ • "'+• ¥ .,. • • -• ", • • 0,• • , • > • > • • > • • ' ' ' • , , . , . ' . , . ' ' . . . ' . . , . ' , < •• • > •• . . • # • ♦ • ~ .......... ♦ .. ♦ ' ..... > • • • • ' <o •• : ·• : C: .s C C: ... ... ,_ ... ,_ >, >, >, >, >, >, >, >,.>, ·~ ·~ ·e ~ .i::. ~ ~ .i::. IQ IQ IQ IQ n, n, IQ IQ IQ E ti-, it 'tl ~1 ~ "!? 6 ~ "O"O 0 ~ ~ g N .... !:l ~ tfa ... Duration N ...... , .................. ~ •••• > • ., ........ ., •• -•• < ........ ' ••••••••• ,,),. ,,.,,.h,l,,, .. ,,,,,,., ... ,,,.,,., . ,, . {· ~ . .,. ., ........ -... . . 2 5 10 25 so 100 200 500 1000 Average recurrence interval (years) NOAA Atlas 14, Volume 6, Version 2 Created (GMT): Thu Mar 30 21:58:38 2017 Back to Top Average recuHence inte,val (years) -1 -2 5 10 25 50 100 -·200 500 1000 Duration -5-mn -2-<Jay -tO-min -3-<ia-y -15-min -4-<tay -30-niln -7-<iay -60-mln -10-day -2-tlf -20-day -3-nr -30-0ay -6-hr -46-day -12-hr -6o-day -24-hr Maps & aerials 100km 1----_,, 60mi Back to Top us Department of Commerce National Oceanic and Atmospheric Administration National Weather Service National Water Center 1325 East West Highway Silver Spring, MD 2091 0 Questions?: HDSC.Questions@noaa.gov Disclaimer San Diego County Hydrology Manual Date: · June 2003 · Table 3-1 Section; Page: RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use I Runoff Coefficient "C" Soil Tx12e NRCS Elements Coun Elements %IMPER. A B Undisturbed Natural Terrain (Natural) Permanent Open Space 0* 0.20 0.25 Low Density Residential (LDR) Residential, 1.0 DU/A or less 10 0.27 0.32 Low Density Residential (LDR) Residential, 2.0 DU/ A or less 20 0.34 0.38 Low Density Residential (LDR) Residential, 2.9 DU/ A or less 25 0.38 0.41 Medium Density Residential (MDR) Residential, 4.3 DU/A or less 30 0.41 0.45 Medium Density Residential (MDR) Residential, 7.3 DU/A or less 40 0.48 0.51 Medium Density Residential (MDR) Residential, 10.9 DU/A or less 45 0.52 0.54 Medium Density Residential (MOR) Residential, 14.5 DU/A or less 50 0.55 0.58 High Density Residential (HOR) Residential, 24.0 DU/A or less 65 0.66 0.67 High Density Residential (HOR) Residential, 43.0 DU/A or less 80 0.76 0.77 Commercial/Industrial (N. Com) Neighborhood Commercial 80 0.76 0.77 Commercial/Industrial (G. Com) General Commercial 85 0.80 0.80 Commercial/Industrial (O.P. Com) Office Professional/Commercial 90 0.83 0.84 Commercial/Industrial (Limited L) Limited Industrial 90 0.83 0.84 Commercial/Industrial (General 1.) General Industrial 95 0.87 0.87 C 0.30 0.36 0.42 0.45 0.48 0.54 0.57 0.60 0.69 0.78 0.78 0.81 0.84 0.84 0.87 3 6 of26 D 0.35 0.4] 0.46 0.49 0.52 0.57 0.60 0.63 0.71 0.79 0.79 0.82 0.85 0.85 0.87 *The values associated with 0% impervious may be used for direct calculation of the runoff coefficient as described in Section 3.1.2 (representing the pervious runoff coefficient, Cp, for the soil type), or for areas that will remain undisturbed in perpetuity. Justification must be given that the area wi II remain natural forever ( e.g., the area is located in Cleveland National Forest). DU/A= dwelling units per acre NRCS = National Resources Conservation Service 3-6 San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 5 of26 Where: C = 0.90 x (%Impervious)+ Cp x (1 -% Impervious) Cp = Pervious Coefficient Runoff Value for the soil type (shown in Table 3-1 as Undisturbed Natural Terrain/Permanent Open Space, 0% Impervious). Soil type can be determined from the soil type map provided in Appendix A. The values in Table 3-1 are typical for most urban areas. However, if the basin contains rural or agricultural land use, parks, golf courses, or other types of nonurban land use that are expected to be permanent, the appropriate value should be selected based upon the soil and cover and approved by the local agency. 3-5 33" 9'<TN 33° 8' 59" N I ffi I i I ;:: r,:i ~ ~ 468311 468311 ;:: r,:i ~ N ~ A Hydrologic Soil Group-San Diego County Area, California (1393 Sheridan Place) 468318 4683'25 Sl32 41383:!l 4683<6 468353 468318 4683'25 Sl32 41383:!l 4683<6 468353 Map Scale: 1:297 if printed 00 A landscape (11" X 8S') sheet ----=====--------========:::iMeters 0 4 8 16 24 ---====------=====Feel: 0 10 20 40 00 Map projection: Web Mercator Comer coordinates: WGS84 Edge tics: UlM Zone 1 lN WGS84 USDA Natural Resources Web Soil Survey National Cooperative Soil Survey '1ft Conservation Service 4138:Bl _, 4138:Bl _, 400374 ;:: ~ ~ ~ 400374 ;:: ~ ~ ~ I ffi I i I I 3/31/2017 Page 1 of 4 33°9'<TN 33" 8' 59"N Hydrologic Soil Group-San Diego County Area, California (1393 Sheridan Place) MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons 0 A 0 AID DB 0 BID □ C □ CID 0 D D Not rated or not available Soil Rating Lines ....,,. A ....,,. AID ....,,. B ....,,. BID ,......, C .....,,. CID ....,,. D ,,. ,,.. Not rated or not available Soil Rating Points ■ A Cl AID ■ B ■ BID USDA Natural Resources rye Conservation Service Cl C ■ CID ■ D Cl Not rated or not available Water Features .,..._, Streams and Canals Transportation t+t Rails _.,,, Interstate Highways --US Routes i::-Z~ Major Roads '1"!:.1'> Local Roads Background • Aerial Photography Web Soil Survey National Cooperative Soil Survey The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: San Diego County Area, California Survey Area Data: Version 10, Sep 12, 2016 Soil map units are labeled (as space allows) for map scales 1 :50,000 or larger. Date(s) aerial images were photographed: Nov 3, 2014-Nov 22,2014 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. 3/31/2017 Page 2 of 4 Hydrologic Soil Group-San Diego County Area, California 1393 Sheridan Place Hydrologic Soil Group Hydrologic Soil Group-Summary by Map Unit -San Diego County Area, California (CA638) Map unit symbol Map unit name Rati ng Acres in AOI Percent of AOI MIC Marina loamy coarse B 0.2 sand, 2 to 9 percent slopes Totals for Area of Interest 0.2 Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (ND, 8/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (ND, 8/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition USDA Natural Resources aiii Conservation Service Web Soil Survey National Cooperative Soil Survey 100.0% 100.0% 3/31/2017 Page 3 of 4 Hydrologic Soil Group-San Diego County Area, California Component Percent Cutoff: None Specified Tie-break Rule: Higher USDA Natural Resources iiiiiiii Conservation Service Web Soil Survey National Cooperative Soil Survey 1393 Sheridan Place 3/31/2017 Page 4 of 4 lij w IJ. z w (.) z ~ (/) i5 w (/) 0:: ::::> 0 (.) 0:::: w I-~ 1001 1,5 I H/1' I I w .,.-;, ~ f § ~ I ::.,""f 130 (/) w I-:::i z 0 20 ~ ~ w :'iE i'.= ?:: 0 ...J u.. 0 10 z :5 0:::: w 6 ;._...._......., ___ __,_ ____ .__ ___ ...._ ________________ o EXAMPLE: Given: Watercourse Distance (D) = 70 Feet Slope (s) = 1.3% Runoff Coefficient (C) = 0.41 Overland Flow Time (T) = 9.5 Minutes T = 1.8 (1.1-C) VD 3\fs SOURCE: Airport Drainage, Federal Aviation Admiriistratlon, 1965 FIGURE Rational Formula -Overland Time of Flow Nomograph 3-3 .b.E Feet 5000 4000 EQUATION Tc "' (1~3)°,385 Tc = Time of concentration (hour.,) L = Waten;:ourse Dist~nce (mll~s) .6.E "' Change In elevation along effective slope tine (See Agure 3-5)(feet) .b.E 3800 2000 1000 0 0 o, soo' ' 400 ' 300 200 100 30 20 10 5 '~ ,~?). ~~ ' ' ' ' ' ' ' ' SOURCE: California Division of Highways (1941) and Kirplch (1940) L Miles Feet '1 4000 3000 0.5 ' 2:000 1800 1600 1400 1200 300 200 L ' Nomograph for Determination of ' ' ' ' 40 30 20 18 16 14 12 10 ' 9 8 7 6 5 3 Tc Time of Concentration (Tc) or Travel Time (Tt) for Natural Watersheds FIGURE ~ Q) c.. 0 en Ql i (I) -0 Concrete Gutter 1~1.s·---.1 Paved RESIDENTIAL STREET ONE SIDE ONLY 20;------+--,--+--+--+-~t--+--+---i~i,,------+--~+--+--+-,,- 18--l-------+----,j~-+--+---++--+-+--+-l-,f-.;;::,...__ 16---f--------f---,j~---1-=-o::::±---Jf---+-+-+--ll#-lf----~-..:: 10 --f-----~'--+-----1---+---+--+--+,jH-t--+----"'-.c:' 9 --f-------.,j~-::J=-..,,..---1---,fi----lf--+-~--l----l---l~---..;::,.,~14-----1f--,#-f-~f--+ s---- 6 5 1.0 --+---,r------t--1---;---:;:; 0.9 -1...::::~==-------f---.,j~---l----+~~-1--11--+--+--IHl-""#.::------I+----' 0.8 -1___,,_ __ ....:::,....,,_4-#---+--+---+-J~,,......+--+-HI--#--_..;:....., __ ~ ____ :~~-+---+--._ 0.7 --f-1-------11-_.;::--...:.. 0.5 2 3 4 5 6 7 8 9 10 20 30 40 50 Discharge (C.F.S.) EXAMPLE: Givan: Q = 10 S • 2.5% Chart gfves: Depth= 0.4, Velocity = 4.4 f.p.s. SOURCE: San Diego County Department of Special District Services Design Manual FIGURE Gutter and Roadway Discharge -Velocity Chart ~ ~ 0 .J2 ... Q) 0.. Q) ~ .!: w a.. 0 ....I U) 0.3 0.2 0.15 0.10 0.09 0.08 0.07 0.06 0.05 0.03 0.02 0.01 0.009 0.008 EQUATION: V = 1.49 R213 s1'2 n 0.2 0 2 / ~ ~~ (.) ~'!:!> 0.007 :J / 0.006 ::J _/ 0.005 ~ 3..........- >- O.~\~ I ~ 0.002 0.001 0.0009 0.0008 0.0007 0.0006 0.0005 0.0004 0.0003 4 5 6 7 8 9 10 20 > /' / -g / i ... Q) a. y., Q) ~ ~ .£ ~ ""g ....I w > GENERAL SOLUTION SOURCE: USDOT, FHWA. HDS-3 (1961) Manning's Equation Nomograph 30 20 ~ 9 8 7 6 5 4 3 2 1.0 0.9 0.8 0.7 0.6 0.5 1)9i./ 9' C . c Q) ·o ~ Q) 0 (.) U) U) w z I (!) ::J 0 a::: 0.01 0.02 0.03 0.04 0.05 0.06 0,07 0.08 0.09 0.10 0.2 0.3 0.4 FIGURE ~ EQUATION s.o~' ' i ......... ' - -... 4.0.tRJl ~ 11-l~I lm ,.,m mtm• _ .. ___ . ___ . __________ ....... __ JJ = 7..44Pso-0.645 l',..:I I ""N I~ l"N.::f'NS'N.R>-lo!.J'H8t~IIIIIII I I I I Ill 1111111!11 = Intensity (in/hr) I I I l:X I ! !'-I I 1'-1 I CN INJN.ln;JJ.INJ.1:11,l,11111111111111 Ps= 6-H6urPrecioitatlonlin) ~ • • ' -· ' • ~' '-· "-rn-rn~ ...... "• II 1111111 u = Duration {min} 2-'I H:I ffilllllffi· · ,; · · •~;;.;• ••;;;•.•~ · -C ~· • • • .... • • ...... ,; .. ;;;; ·rN, --.... m ~ 8 .::, ~ ... t::I I 111111111111111 MIii~ 1111• mmmttBI E::11111111111111111111111111111111•1111mmtR m, ' • :l' (D Q. lt'"f-f~t-l;:Hlll'tiffitft'Nit:!lt 6.0 "2. +-Ncl-H"H-1-P'liitt+Hlttfflolm-s.s I 5.0 g ~-.d--1-+~H-N:tfl'lt:f-tmtt 4:5 l -·-------------I 4.0 en l'MJ.!1111" 3·5 ~ ,~ , , 1 ~ "N.J I IMl11nmul 30 0.41 I I I I I I I I I 11111 !I lllll!lllllltllllll!lllllllllllllllllllllli:ffll,IJ I I 111 N-lJ I lllln .. :..:::::::: N 14.J ! 111t: ~;~;;;~; 2:5 ... , 0.3 1.5 0.2 I I I I I I I I I I I I i--l-utlill.1:l:~f j.UiHI-J:::l::W:l:t.W~~~::!:Utt:!tl:'.'i.ffifflll-1.0 -1-1-t.:t:t:t=J::t:t.::t:1=1=1--1-4-)...1 t I II I I 11 l+l#l#I 111111 111 H-H+l-1-l·l+H+l+H!H 11111 I I I H I I I I I II I l·H-l#H-14+1!1 [I Ii 0.1, l T I ! I TT[ITII I I I I II I lf!ll[lllllllllllllOJfTITTPITTmm111rn11 I 1111111111o:rmrrpm1~ 40501 2 3 4 56 lUllUITIITTTTTrl!IIIIIIHIIIIIIIIJIIII I I I I I 11 11111 IJ lflfil1111111 5 -6 7 8 9 10 15 20 30 Minutes · Houra Duration Intensity-Duration Design Chart • Tempiate Directions for Applltatfon: ( 1) From precipitation maps determine 6 hr and 24 hr amounts for the selected frequency. These maps are (nduded in the Coumy Hydrology Manual (10, 50, and 100 yr maps Included in the Design and Procedure Manual}. . {2) Adjust 6 hr precipitation (if necessary) so that itis within the range of 45% to 65% of the 24 hr precipitation (not applicaple to Desert). (3) Piot 6 hr precipitation on the right side of the chart . (4) Draw a line through the point parallel to the plotted lines .. . (5) This line_ is the intensity-<iuration curve for the location being analyzed. Application Form: {a) Selected frequency __ year .. Pa (b)Ps= in P24 = ~ = __ ., -'P24 (c} Adjusted P6<2l::: __ in. (d) Ix= __ min. (e) I= __ in./hr. %{2) Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965 . I , ~---.... ~ ······l-·J·-_ .. _...L-...... ~ .. --i---, ~ratloni···: ···~1f !--~-+2is r-}·, 3fs ··-~·-_r 4js··-:· ~--I sis··!-~--,. , ==~~::~ -~~~~-t~:r-~1-~~~~-~·f B~j ~:~ -~~119~~t~~~l~~:: l ~~:~~ -~:~J~ :~:: t~'.:1~:-1 ~:~!1;:~~:::-::~: -~:~ k~:~1~:~;f~1~1 ........... 20 .,,1.os .. 11.s2t2.1s1.2.59i3.23,3.nJ.4.31 4.ss I s.39, s.93T s.4s. ·-····--··~ -~:~_t!~~t~;.J~:~;t~: .~:~ t~--I~:i_;;~~.r_;~.L~:~:' ______ 4o o.69 p.o3~_1:381_1.1212.01+2.41f,2.1e. _3.10,-1 3.45.~3.79·!·4.,3 ,, __ _,_,so .,0.60 .. j.0,90!1.19v49} 1,79j_2.09 2.39 2.69 ,_2.98 ~.28 _.3'.58 . -·---: .g·~-1;g::'.~::1-:::i-::~1::~f~:~-·--;:!!+~:~+~·i.~:!: ··-120 o.34 0.1)0.~I o.Bs k~H.191"1.36 ···{53 • 1.10.~·1.a1 l 2.04· . ~:Jso __ o.2910.4410.s_ ~lo·73!0.ssj1,03J:1.1e·b:32l:u1J·,.o2· ·,:1s ·-----1!9 :.9:.~ .... Q,~.9-.it~~-tQ&~ .• .ct~ 0.91 .1.04 J:~~-.J.J.31 t.44 1,57 -·-·---~: g:~--tg~,g~~i ~::;-1~::1g::l-~~s1l:+~: ·~::++:~ .. "-···aso o.11hr2s1 o.33 l o.42 ! o:solo.ssro.si ro:1sl o.8'1 I o:92 l 1 ,oo· 3-1 }t~ San Diego County Hydrology Manual Date: June 2003 3.2 DEVELOPING INPUT DATA FOR THE RATIONAL METHOD Section: Page: 3 20 of26 This section describes the development of the necessary data to perform RM calculations. Section 3.3 describes the RM calculation process. Input data for calculating peak flows and Tc's with the RM should be developed as follows: l. On a topographic base map, outline the overall drainage area boundary, show~g adjacent drains, existing and proposed drains, and overland flow paths. 2. Verify the accuracy of the drainage map in the field. 3. Divide the drainage area into subareas by locating significant points of interest. These divisions should be based on topography, soil type, and land use. Ensure that an appropriate first subarea is delineated. For natural areas, the first subarea flow path length should be less than or equal to 4,000 feet plus the overland flow length (fable 3-2). For developed areas, the initial subarea flow path length should be consistent with Table 3-2. The topography and slope within the initial subarea should be generally unifo1m. 4. Working from upstream to downstream, assign a number representing each subarea in the drainage system to each point of interest. Figure 3-8 provides guidelines for node numbers for geographic information system (GIS)-based studies. 5. Measure each subarea in the drainage area to determine its size in acres (A). 6. Determine the length and effective slope of the flow path in each subarea. 7. Identify the soil type for each subarea. 3-20 .-Study Area SC • r · l I . '7 ' \ .. ( /' ·. ,,./ l,• Study Area LA 0 Define Study Areas (Two-Letter ID) 0 Define Maps (or Subregions on Region Basis) 0 Define Model Subareas on Map Basis ,, ~., .. ,' ,, ~,,,----".... ,,. .. --...... _ .. .,. .... -"' .·· . . G) Define Major Flowpaths in Study Area 0 Define Regions on Study Area Basis Subarea ID= (LA010112) N;:::_ l Region# Study Area (ID) #---1 11 © Define Model Nodes (Intersection of Subarea Boundaries with Flowpath Lines) GIS/Hydrologic Model Data Base Linkage Setup: Nodes, Subareas, Links LA 01 01 03 0 Number Nodes r ·~-USR E1 San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 22 of26 8. ·Determine the runoff coefficient (C) for each subarea based on Table 3-1. If the subarea contains more than one type of development classification, use a proportionate average for C. In determining C for the subarea, use future land use taken from the applicable community plan, Multiple Species Conservation Plan, National Forest land use plan, etc. 9. Calculate the CA value for the subarea. 10. Calculate the 1:(CA) value(s) for the subareas upstream of the point(s) of interest. 11. Determine P6 and P24 for the study using the isopluvial maps provided in Appendix B. If necessary, adjust the value for P6 to be within 45% to 65% of the value for P24. See Section 3.3 for a description of the RM calculation process. 3.3 PERFORMING RATIONAL METHOD CALCULATIONS This section describes the RM calculation process. Using the input data, calculation of peak flows and Tc's should be performed as follows: l. Determine Ti for the first subarea. Use Table 3-2 or Figure 3-3 as discussed in Section 3.1.4. If the watershed is natural, the travel time to the downstream end of the first subarea can be added to Ti to obtain the Tc. Refer to paragraph 3.1.4.2 (a). 2. Determine I for the subarea using Figure 3-1. If Ti was less than 5 minutes, use the 5 minute time to determine intensity for calculating the flow. 3. Calculate the peak discharge flow rate for the subarea, where Qp = L(CA) I. In case that the downstream flow rate is less than the upstream flow rate, due to the long travel time that is not offset by the additional subarea runoff, use the upstream peak flow for design purposes until downstream flows increase again. 3-22 San Diego County Hydrology Manual Date: June 2003 4. Estimate the Tt to the next point of interest. 5. Add the Tt to the previous Tc to obtain a new Tc. Section: Page: 6. Continue with step 2, above, until the final point of interest is reached. 3 23 of26 Note: The MRM should be used to calculate the peak discharge when there is a junction from independent subareas into the drainage system. 3.4 MODIFIED RATIONAL METHOD (FOR JUNCTION ANALYSIS) The purpose of this section is to describe the steps necessary to develop a hydrology report for a small watershed using the MRM. It is necessary to use the MRM if the watershed contains junctions of independent drainage systems. The process is based on the design manuals of the City/County of San Diego. The general process description for using this method, including an example of the application of this method, is described below. The engineer should only use the MRM for drainage areas up to approximately 1 square mile in size. If the watershed will significantly exceed I square mile then the NRCS method described in Section 4 should be used. 1'he engineer may choose to use either the RM or the MRM for calculations for up to an approximately I-square-mile area and then transition the study to the NRCS method for additional downstream areas that exceed approximately 1 square mile. The transition process is described in Section 4. 3.4.1 Modified Rational Method General Process Description The general process for the MRM differs from the RM only when a junction of independent drainage systems is reached. The peak Q, Tc, and I for each of the independent drainage systems at the point of the junction are calculated by the RM. The independent drainage systems are then combined using the MRM procedure described below. The peak Q, Tc, and I for each of the independent drainage systems at the point of the junction must be calculated prior to using the MRM procedure to combine the independent drainage systems, as these 3-23 San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 24 of26 values will be used for the MRM calculations. After the independent drainage systems have been combined, RM calculations are continued to the next point of interest. 3.4.2 Procedure for Combining Independent Drainage Systems at a Junction Calculate the peak Q, Tc, and I for each of the independent drainage systems at the point of the junction. These values will be used for the MRM calculations. At the junction of two or more independent drainage systems, the respective peak flows are combined to obtain the maximum flow out of the junction at Tc• Based on the approximation that total runoff increases directly in proportion to time, a general equation may be written to determine the maximum Q and its corresponding Tc using the peak Q, Tc, and I for each of the independent drainage systems at the point immediately before the junction. The general equation requires that contributing Q's be numbered in order of increasing Tc. Let Qr, Tr, and 11 correspond to the tributary area with the shortest Tc. Likewise, let Q2, T2, and h correspond to the tributary area with the next longer Tc; Q3, T3, and J3 correspond to the tributary area with the next longer Tc; and so on. When only two independent drainage systems are combined, leave Q3, T3, and h out of the equation. Combine the independent drainage systems using the junction equation below: Junction Equation: T1 < T2 < T3 3-24 San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 25 of26 Calculate Qn, Qn, and Qn-Select the largest Q and use the Tc associated with that Q for further calculations (see the three Notes for options). If the largest calculated Q's are equal (e.g., QT1 = Qu > Qn), use the shorter of the Tc's associated with that Q. This equation may be expanded for a junction of more than three independent drainage systems using the same concept. The concept is that when Q from a selected subarea ( e.g., Q2) is combined with Q from another subarea with a shorter Tc (e.g., Qi), the Q from the subarea with the shorter Tc is reduced by the ratio of the I's (b/11); and when Q from a selected subarea (e.g., Q2) is combined with Q from another subarea with a longer Tc (e.g., Q3), the Q from the subarea with the longer Tc is reduced by the ratio of the Tc's (T2/T3). Note #1: At a junction of two independent drainage systems that have the same Tc, the tributary flows may be added to obtain the Qp- This can be verified by using the junction equation above. Let Q3, T3, and h = 0. When T1 and T2 are the same, 11 and hare also the same, and T1/T2 and Ji/1 1 = I. T1/T2 and h/11 are cancelled from the equations. At this point, Qn = Qn = Q1 + Q2. Note #2: In the upstream part of a watershed, a conservative computation is acceptable. When the times of concentration (Tc's) are relatively close in magnitude (within 10%), use the shorter Tc for the intensity and the equation Q = Z:(CA)I. Note #3: . An optional method of determining the Tc is to use the equation Tc= [(L (CA)7.44 P6)/Q] us 64-This equation is from Q = L(CA)I = I:(CA)(7.44 P6/Tc· ' ) and solving for Tc. The advantage in. this option is that the Tc is consistent with the peak flow Q, and avoids inappropriate fluctuation in downstream flows in some cases. 3-25