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HomeMy WebLinkAboutCDP 2017-0038; SHERIDAN PLACE ADU; DRAINAGE REPORT; 2017-03-31- ·::~;\~-.• ~~) APR 1 7 2017 CITY C;:,f.:,:LSBAD PLAf\.lN!NG DIVIS!ON DRAINAGE. REPORT 1393 SHERIDAN PLACE APN 206-042-47 CITY OF CARLSBAD Prepared for: Prophet Solutions, Inc. 5845 Avenida Encinas, Suite 138 Carlsbad, CA 92008 Prepared by: bliA, Inc. land planning, civil engineering, surveying 5115 Avenida Encinas, Suite L Carlsbad, CA 92008-4387 (760) 931-8700 March 31, 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 .................................................................................................................................... 7 1.8 Declaration of Responsible Charge ............................................................................................ 9 Chapter 2 -Existing & Developed Condition Hydrology Maps ................................................................... 10 Chapter 3 -Calculations .................................................................................................................................. 12 3.1 Existing Condition Hydrology Calculations .............................................................................. 12 100-Year Storm ...................................................................................................................... 13 3.2 Developed Condition Hydrology Calculations ......................................................................... 15 100-Year Storm ...................................................................................................................... 16 Chapter 4 -References ..................................................................................................................................... 20 4.1 Methodology-Rational Method Peak Flow Determination ................................................... 20 DRAiNAGE REpORT 1}9} SlirnidAN-PIAcE, CARlsbAd, CA bl-IA, Inc. 2 DRAiNAGE REpORT CHAPTER 1 -DISCUSSION VICINITY CITY OF OCEANSIDE PACIFIC OCEAN 78 MAP ___ u_9_}_S_l-i_rn_id_A_N_P_IA_c_E_, _C_AR_Ls_b_A_d,_C_A _____________________ b_~_A_, _ln_c_. r--T7_ 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 1393 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 storm water conveyance system. The 100-year storm frequency will be analyzed. 1.3 PROJECT DESCRIPTION The project site is located at 1393 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 comer 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 4 -References). Onsite soils areas have been assumed to be compacted in the existing condition to represent the current condition of the site. DRAiNAGE REpORT 1}9} S~ERidAN PIACE, CARlsbAd, CA bl-tA, Inc. 4 L__ 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 Concentration (cfs) (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 Concentration (cfs) (min) Northwest Corner 0.16 0.48 8.41 0RAiNAGE REpORT U9} ShrnidAN PLAcE, CARlsbAd, CA bliA, Inc. 1.6 STUDY METHOD The method of analysis was based on the Rational Method according to the San Diego County Hydrology Manual (SD HM). 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. 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 4 -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 SD HM. Rainfall Isopluvial Maps from the SD HM were used to determine P 6 for 100-year storm, see References. RickRat Hydro was used to perform Rational Method hydrographs. The design storm patter 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): 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 (l[CA]). Table 3 summarizes the composite C-values calculated in the existing and proposed conditions. DRAiNAGE REpORT 1}9} S~ERidAN PLAcE, CARlsbAd, CA b!-iA, Inc. 6 TABLE 3-Weighted Runoff Coefficient Calculations: Existing Hydrology Total Acreage C1 A1 (acres) C2 A2 (acres) Ccomp 0.16 0.25 0.16 0.87 0.00 0.25 Proposed Hydrology Total Acreage C1 A1 (acres) C2 A2 (acres) Ccomp 0.16 0.25 0.07 0.87 0.09 0.61 Note: C-values taken from Table 3-1 of San Diego County Hydrology Manual, consistent with on-site existing soil types. See References. 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: 100-Year Peak Flow Time of Concentration Drainage Area (acres) (ds) (min) Pre-Developed Condition 0.16 0.21 9.26 Post-Developed Condition 0.16 0.48 8.41 DIFFERENCE 0.00 0.27 -0.85 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 0.27 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". 0RAiNAGE REpORT U9} %rnidAN PlAcE, CARlsbAd, CA bliA, Inc. 7 Peak flow rates listed above were generated based on criteria set forth in "San Diego County Hydrology Manual" ( methodology presented in Chapter 4 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 QlOO flowrate without any adverse effects. 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 ___ u_9_}_S_li_rn_id_A_N_P_IA_c_E_, _C_AR_l_sb_A_d_, _c_A ____________________ b_Ji_A_, _ln_c~. 18[___ 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. Bruce Rice R.C.E. 60676 DRAiNAGE REPORT 1}9} SlirnidAN PLAcE, CARlsbAd, CA Date bl-iA, Inc. 9 CHAPTER2 EXISTING & DEVELOPED CONDITION HYDROLOGY MAPS DRAiNAGE REPORT 1}9} S1-trnidAN Pl.AcE, CARlsbAd, CA MtA, Inc. 10 L__ ---+-,, AC [x,SnNG s· PVC \ WA TE:RLINE PER Dl<G. <OJ· 8 ..----,, _:------'11 ' 1· WATER S[R\1C[ CONN[CnON -- SHERIDAN PLACE cc.i-.c. BUILDING 7 I ~ _J BUILDING K\C1v1I 3O\0810\DWG\SWMP\1037-0810-PROP HYDRO.dwg, 3/31/2017 2 19.24 PM £X/SnNG 6. CURB & cumR rnsnNc cwt. SJO[Y,ALJ< 206-042-26 [XISnNG BUILDiNG BUILDING rnsn11c FfNCf TO 8[ R[U011:D DEVELOPED CONDITION HYDROLOGY MAP 1393 SHERIDAN PLACE, CITY OF CARLSBAD EXISTING I- WA TfR LATERAL P[R owe. •oJ-8 I ,. UAIN BUILDING 5050 rr • 50.00 PAD -~--- ·' MAP NO. 14626 PRO.£JT 80UON1RY LOT 5 rnsn11c F[NCC TO 8[ R[M011:D [XISnNG 8UtLOWG LOT 12 MAP NO. 4751 <9 1s rs ;,-5-,21£- , .. PVC Sfr,fR [ASfM[NT PER • LOT 15 ~, r.===::::::J=::;l : I SPA 50.50 5037 TC 4810 /[ [XIS n~JG 8UtL01NG I I I I SfllfR LATERAL ' ' DOC. 2016-07JJ60 RfCORDED Z/19/16 'b3-d' LOT 13 10· SCALE: 1 ~ • 10' 20· JO' I LEGEND SURFACE NOOF: SURFACE FlOW. 100 >'cAR BASIN AR[A RUNOFr COUF1Cl[NT ROOF AR[A CONCR['TF LANDSCAPING D[COI.IPOSE:D GRANl'TF BASJN BOUNDARY BASIN SUB-BOUNDARY PROJE:CT BOUNDARY FLOMJN[ @ @ C=0.61 I' I· PROJECT CHARACTERISTICS PARCEL AREA 0.16 ACRES APN 206-042-47 SOIL TYPE B DEPTH TO GROUNDWATER > 20 FEET ·I SUMMARY OF DEVELOPED CONDITIONS PEAK FLOW DISCHARGE LOCATION I DRAINAGE AREA (AC} I 100-YEAR PEAi( FLOW I TIME OF (CFS) CONCENTRATION (MIN) NORTHWEST CORNER I b~A,lnc. 0.16 I 0.51 I 8.43 0.07 0.87 0.09 0.61 Note·C...,..1luH ~ken fromT•ble3·1 of Slt1 o .. oCotlntvHvdroloav tv11ru,u,1, cOt1sinerit with on-1;,tt~litlnt soil f't1)eS. Set Refertnc~. land ploOOl'lg. cM engw,eerhg. ,urveytng DEVELOPED CONDITION HYDROLOGY MAP 1393 SHERIDAN PLACE CITY OF CARLSBAD 5115 AVENIOA ENCINAS SUITE "L" CARLSBAD. CA. 92008-4387 (760) 931-8700 ~ ~ ----- -."' _,, __ ,, 4C BUILDING K.\C1,..1I 30\0810\0WG\SWMP\1037-0810-PROP HYORO.dwg, 3/31/2017 2:2419 PM EXISTING CONDITION HYDROLOGY MAP 1393 SHERIDAN PLACE, CITY OF CARLSBAD I [XtSnNG s· PVC WA TERLJN[ PfR Di!G <OJ-8 i Ji_ .. L .. ~ ,, ____ .. --·t j / ---------=-=- SHERIDAN PLACE 7 I ~ _J [XISnNG CURB INLET -7 BUILDING I _J .. [XISnNG 5• CURB di GUnER £XIS nNG0 • coo/: . 51D[WALJ( 206-042-26 PRo..£CT BOUDNARY I \ ' , @]) \ Ca0.25 \ \ I \ I •. I I I I [XISllNG 1· WATER LATERAL P£R owe •oJ-8 £XIS nNG r FORC£ MAIN LA TE"RAL PER Oi!G <OJ-8 ... :,; ,. '!,·"' -~-----------., \ I I '@ \ C•0.25 \ I Gt1T,E ----_. ___ ...,._...., __________ ,... [XISnNG BUILDING BUILDING T LOT 15 MAP NO 14626 -ri LOT 5 / [XIS nNG BU~OING ---------. PRO.~.Jr BOUDNARY ~x,s!J LSH1~ I I I I L.__ ----- ' T" .\-' .. 8°0RA"'1-0E S-OR~"fq,. . ' 10· 5· o· 10· 20· ~ $CALL 1· m 10· LOT 12 MAP NO , .. .. :. i,.::. .. ~ ' "'I:·, " .. , .. .... .. · ... ... JO' I LOT 13 LEGEND SURFACE: NOOE @ SURFACE: now. 100 rfAR BASIN AREA <@) RUNOFr cocma£N r C•0.25 BASIN BOUNDARY BASIN SUB-BOUNDARY ·-------· PROJ£CT BOUNDARY ------- FlO"1./N[ PROJECT CHARACTERISTICS PARCEL AREA 0.16ACRES APN 206-042--47 SOIL TYPE • DEPTH TO GROUNDWATER > 20FE£T SUMMARY OF EXISTING CONDITION PEAK FLOW DISCHARGE LOCATION I DRAINAGE AREA (AC) I 100-YEAR PEAi( FLOW I TIME OF (CFS) CONCENTRATION (MIN) NORTHWEST CORNER l b~A.lnc. 0.16 I 0.21 I 9.26 WEIGHTED RUNOFF COEFFICIENT CALCULATION: Existing Hydrology Total Acre~ge C1 A,cxr.w C1 Au-~ c_ 0.16 0 2S O 16 0.87 0.00 0.25 Hott'· C-v•lu~ taken from T•ble 3-1 of Siln Otego County Hydrolorv ~nu;il,c01n,1uen1 with on·sl1ee,utinc s01I ty~. See ~e-rnces land planning, cM engheenng. surveyt,g EXISTING CONDITION HYDROLOGY MAP 1393 SHERIDAN PLACE CITY OF CARLSBAD 5115 AVENIOA ENCINAS SUITE ·L" CARLSBAO, CA. 92008-4:l87 (760) 931-8700 CHAPTER3 CALCULATIONS 3.1 -Existing Condition Hydrology Calculations DRAiNAGE REpORT 1}9} SJ.irnidAN PLAcE, CARlsbAd, CA bl-IA, Inc. 12 i L___ 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 * 1393 Sheridan Place ************************************************************************** FILE NAME: 0810El00.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 STREETFLOW HALF-CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: WIDTH CROSSFALL IN-/ OUT-/PARK-HEIGHT WIDTH LIP HIKE NO. (FT) (FT) SIDE/ SIDE/ WAY (FT) (FT) (FT) (FT) MODEL* MANNING FACTOR (n) 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150 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.* **************************************************************************** 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 1}9} SlirnidAN PI.AcE, CARlsbAd, CA bl-IA, Inc. L__ 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= 7 >>>>>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 **************************************************************************** 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 SUBAREA AREA(ACRES) 0.11 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 U9} SliERidAN PIAcE, CARlsbAd, CA 9.26 bl-iA, Inc. 14 CHAPTER3 CALCULATIONS 3.2 -Developed Condition Hydrology Calculations DRAiNAGE REpORT 1}9} S1-tERidAN PIAcE, CARlsbAd, CA M-iA, Inc. 15 L_ 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 * 1393 Sheridan Place ************************************************************************** FILE NAME: 0810Pl00.DAT TIME/DATE OF STUDY: 09:47 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 STREETFLOW HALF-CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: WIDTH CROSSFALL IN-/ OUT-/PARK-HEIGHT WIDTH LIP HIKE NO. (FT) (FT) SIDE/ SIDE/ WAY (FT) (FT) (FT) (FT) MODEL* MANNING FACTOR (n) 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150 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.* **************************************************************************** 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= .6100 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 59.00 UPSTREAM ELEVATION(FEET) = 50.04 DOWNSTREAM ELEVATION(FEET) = 49.63 ELEVATION DIFFERENCE(FEET) = 0.41 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 7.570 DRAiNAGE REpORT 1}9} S1-tERidAN PIAcE, CARlsbAd, CA bl-IA, Inc. 16 --------~------------------------------------------------- WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH= 57.80 (Reference: Table 3-lB of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.262 SUBAREA RUNOFF(CFS) 0.10 TOTAL AREA(ACRES) = 0.03 TOTAL RUNOFF(CFS) 0.10 **************************************************************************** FLOW PROCESS FROM NODE 11. 00 TO NODE 11.00 IS CODE= >>>>>USER SPECIFIED HYDROLOGY INFORMATION AT NODE<<<<< USER-SPECIFIED VALUES ARE AS FOLLOWS: TC(MIN) = 7.57 RAIN INTENSITY(INCH/HOUR) = 5.26 TOTAL AREA(ACRES) = 0.03 TOTAL RUNOFF(CFS) = 0.10 7 **************************************************************************** FLOW PROCESS FROM NODE 11. 00 TO NODE 12.00 IS CODE= 31 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 48.68 DOWNSTREAM(FEET) FLOW LENGTH(FEET) = 43.80 MANNING'S N 0.011 DEPTH OF FLOW IN 6.0 INCH PIPE IS 1.9 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 1.84 ESTIMATED PIPE DIAMETER(INCH) = 6.00 PIPE-FLOW(CFS) = 0.10 NUMBER OF PIPES PIPE TRAVEL TIME(MIN.) = 0.40 Tc(MIN.) = 1 48.48 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 7.97 12.00 102.80 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) = 5.092 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .6100 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT= 0.6240 SUBAREA AREA(ACRES) 0.02 SUBAREA RUNOFF(CFS) TOTAL AREA(ACRES) = 0.0 TOTAL RUNOFF(CFS) = TC(MIN.) = 7.97 0.06 0.16 **************************************************************************** FLOW PROCESS FROM NODE 12.00 TO NODE 13.00 IS CODE= 31 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 48.48 DOWNSTREAM(FEET) FLOW LENGTH(FEET) = 37.33 MANNING'S N 0.011 DEPTH OF FLOW IN 6.0 INCH PIPE IS 2.5 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 2.01 ESTIMATED PIPE DIAMETER(INCH) = 6.00 PIPE-FLOW(CFS) = 0.16 NUMBER OF PIPES 1 48.31 PIPE TRAVEL TIME(MIN.) = 0.31 LONGEST FLOWPATH FROM NODE Tc (MIN.) = 10.00 TO NODE 8.27 13.00 140.13 FEET. **************************************************************************** DRAiNAGE REpORT 1}9} SliERidAN PlAcE, CARlsbAd, CA bl-tA, Inc. 17 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): USER-SPECIFIED RUNOFF COEFFICIENT= .6100 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 74.70 UPSTREAM ELEVATION(FEET) = 50.04 DOWNSTREAM ELEVATION(FEET) = 49.47 ELEVATION DIFFERENCE(FEET) = 0.57 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 7.509 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH= 60.52 (Reference: Table 3-lB of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.290 SUBAREA RUNOFF(CFS) 0.10 TOTAL AREA(ACRES) = 0.03 TOTAL RUNOFF(CFS) 0.10 **************************************************************************** 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) = 5.290 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .6100 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF SUBAREA AREA(ACRES) TOTAL AREA(ACRES) = TC(MIN.) = 7.51 COEFFICIENT= 0.6100 0.03 SUBAREA RUNOFF(CFS) 0.1 TOTAL RUNOFF(CFS) = 0.10 0.19 **************************************************************************** FLOW PROCESS FROM NODE 16.00 TO NODE 13.00 IS CODE= 31 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRO SUBAREA<<<<< >>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 48.52 DOWNSTREAM(FEET) FLOW LENGTH(FEET) = 68.00 MANNING'S N = 0.011 DEPTH OF FLOW IN 6.0 INCH PIPE IS 3.2 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 1.84 ESTIMATED PIPE DIAMETER(INCH) = 6.00 PIPE-FLOW(CFS) = 0.19 NUMBER OF PIPES 1 48.31 PIPE TRAVEL TIME(MIN.) = 0.62 LONGEST FLOWPATH FROM NODE Tc (MIN.) = 15.00 TO NODE 8.12 13.00 142.70 FEET. **************************************************************************** FLOW PROCESS FROM NODE 13.00 TO NODE 13.00 IS CODE= 11 >>>>>CONFLUENCE MEMORY BANK# 1 WITH THE MAIN-STREAM MEMORY<<<<< **MAINSTREAM CONFLUENCE DATA** DRAiNAGE REpORT 1}9} ShERidAN PLAcE, CARlsbAd, CA bl-tA, Inc. 18 STREAM RUNOFF Tc INTENSITY AREA NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE) 1 0.19 8.12 5.028 0.06 LONGEST FLOWPATH FROM NODE 15.00 TO NODE 13.00 142.70 FEET. ** MEMORY BANK# 1 CONFLUENCE DATA** STREAM RUNOFF Tc INTENSITY AREA NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE) 1 0.16 8.27 4.969 0.05 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 13.00 140 .13 FEET. ** PEAK FLOW RATE TABLE** STREAM RUNOFF Tc INTENSITY NUMBER (CFS) (MIN.) (INCH/HOUR) 1 0.35 8.12 5.028 2 0.35 8.27 4.969 COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS: PEAK FLOW RATE(CFS) 0.35 Tc(MIN.) = 8.27 TOTAL AREA(ACRES) = 0.1 **************************************************************************** FLOW PROCESS FROM NODE 13.00 TO NODE 14.00 IS CODE= 31 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 48.31 DOWNSTREAM(FEET) FLOW LENGTH(FEET) = 22.50 MANNING'S N = 0.011 DEPTH OF FLOW IN 6.0 INCH PIPE IS 3.6 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 2.86 ESTIMATED PIPE DIAMETER(INCH) = 6.00 PIPE-FLOW(CFS) = 0.35 NUMBER OF PIPES 0.13 Tc(MIN.) = 1 48.16 PIPE TRAVEL TIME(MIN.) = LONGEST FLOWPATH FROM NODE 15.00 TO NODE 8.41 14.00 165.20 FEET. **************************************************************************** FLOW PROCESS FROM NODE 14.00 TO NODE 14.00 IS CODE= 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.919 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .6100 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT= 0.6144 SUBAREA AREA(ACRES) 0.05 SUBAREA RUNOFF(CFS) TOTAL AREA(ACRES) = 0.2 TOTAL RUNOFF(CFS) = TC(MIN.) = 8.41 END OF STUDY SUMMARY: TOTAL AREA(ACRES) PEAK FLOW RATE(CFS) 0 . 2 TC (MIN. ) = 0.48 END OF RATIONAL METHOD ANALYSIS DRAiNAGE REpORT 1}9} S1-tERidAN PLAcE, CARlsbAd, CA 8.41 0.15 0.48 bliA, Inc. 19 L_ CHAPTER4 REFERENCES 4.1 -Methodology -Rational Method Peak Flow Determination DRAiNAGE REpORT __ 1_}9_}_S_lu_R_id_AN_P_IA_c.....;_E,_C_A_Rl_sb_Ad-'-,_C_A _________________ b_li---'A,_l_nc_. _12ol__ Precipitation Frequency Data Server Page 1 of 4 @ 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, Carl 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 PCS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Duration I 1 II 2 II 5 II Average recurrence Interval (years) 10 II 25 II 50 I 100 II 200 II 500 II 1000 I s-mln I 0.131 0.166 0.214 0.256 0.316 0.365 0.418 0.476 0.560 0.630 (0.110-0.157) (0.139-0.199 0.180-0.258) (0.213-0.311 (0.253-0.399 0.286-0.471) (0.319-0.554 (0.353-0.649 0.397-0. 798) (0.430-0.932 i 10-mln I 0.188 0.238 0.307 0.367 0.453 0.524 0.600 0.683 0.803 0.903 (0.158-0.226) (0.200-0.286 0.257-0.370 (0.305-0.446 (0.363-0.571 0.410-0.675) (0.458-0.794 (0.506-0.931 (0.569-1.14) (0.617-1.34) I 15-mln I 0.227 0.288 0.372 lio.3~9~54ol 0.548 0.634 0.725 0.825 0.971 1.09 0.191-0.273 0.242-0.346 0.311-0.448 0.439-0.691 0.496-0.817 II0.554-0.960 I0.611 -1.13) 10.688-1.38) I0.746-1.621 I I 3o-mln l1co.2~i~~3871 lco.~2~ 8 490~ 0.526 0.629 0.776 o.897 1.03 I 1.17 II 1.38 II 1.55 I 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-mln 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) El o.691 o.860 1.09 I 1.29 II 1.57 II 1.80 ~ 2.05 II 2.31 I 2.69 3.00 '0.582-0.830) I0.723-1.03) I0.915-1.32): (1.07-1.57) :: (1.26-1.98) :: (1 .41-2.32) ~ (1.56-2.71) :: (1 .71-3.15): (1 .91-3.83) (2.05-4.44) B 0.894 I 1.12 II 1.42 II 1.67 II 2.03 II 2.31 I 2.61 2.93 I ,2.3t!:.81) 11 (2.5!?:.53) I 10.752-1.07) :(0.938-1.34):: (1.19-1.71) :: (1.39-2.03) :: (1.63-2.56) :: (1 .81-2.98): (1.99-3.46) (2.17-3.99) ~ (0.~9~~.35) 1.43 I c1.!~22, II (1.8~·~:.64, I 2.63 I (2.~~85) 11 (2.!!:«) I 3.74 4.26 4.67 (1.21-1.72) (2.11-3.32) (2.77-5.10) (3.02-6.07) (3.19-6.91) 24-hr 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) 2-day 1.68 2.20 I 12.5;·~:.34) 11 (2.9!~:.ooi II (3.5~·~:.021 11 (3.9~·?:.82) I (4.2!~:.67) 11 !4.!·~61) 11 !5.0~~99) I 7.30 11.48-1.95) 11.94-2.55) 15.36-10.1) I 3-day II p.~·~: 18) II (2.1~·~J.86J II (2.~~:.76) II (3.3~~:52) II (3.9~?~.69) II (4.4~~:.61) I (4.8~~i6oJ II (5.2~?:.69) II (5.icl~o.3J II (6.1~!~1.6) I I 4-day I 2.04 I 2.69 II 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) (4.37-6.251 (4.89-7.27) (5.38-8.37) (5.85-9.59) (6.41 -11.4) (6.80-12.9) 7-day 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) 10-day 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) 20-day 3.19 ... 30 I 5.79 II 7.04 II 8.80 II 10.2 I 11.6 II 13.2 II 15.3 II 17.0 I 12.82-3.69) 13.79-4.98) : (5.09-6.72) :: (6.14-8.24) :: !7,43-10.6) :: !8,44-12.5) : !9,42-14.7) :: (10.4-17.0) :: !11.6-20.6) :: (12.5-23.6) : I 3o-day II (3.3;·?I.37) II (4.4~~~91) II (6.o~·~:.03) II (7.!:88) II (8.9~~-~2.8) I 12.3 14.2 I 16.1 II 18.8 II 21 .0 I (10.2-15.2) (11.5-17.8) (12.7-20.8) (14.3-25.3) (15.4-29.2) 145-day I 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) 60-day 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) ' 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 Sivan 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 ~ecked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more infonmation. Back to Top htto://hdsc.nws.noaa.e:ov/hdsc/ofds/ofds orintoae:e.html?lat=33.1501 &lon=-117 .3392&dat... 3/30/2017 Precipitation Frequency Data Server 35 30 ] 25 £ a. QI 20 _, C: 0 .:; 15 ~ ·a. v ~ Q. 10 5 0 C: e ,;., 35 30 1 25 'R QI 20 _, C: B 15 5 ci. £ 10 5 01 PF graphical PDS-based depth-duration-frequency (DDF) curves Latitude: 33.1501°, Longitude: -117.3392° . . . . , ... ". . . . . . . . . ,, . . . "· . ~. . . . . . . . . . . . . . . . . . . . . . .. .. • ... •:..... . . ~ . . ... ~ . i· ~ ... ! .. ·:-!· ... ~ . -·-.... . . . . :• . : ~ . : . -: .... o I O 0 •• • .... -:-••••• , .•••• ,(-••.•• -.• 1· .•.. :·· -.• :-..... -:-......... • .. ~-••. -:-• -· . . . . . . . . . . . . . . . . . . . . . . . . . t I O O o . . . . . . . . . . .,. .. , .... ' ........... , ... -................... , ..... ' ...... .. . . . . . . .................................. ···-·· . . . . . . . . . . . . . . . . ....................................... . . .. . . .. C: C: C: C: ... ... ... ... ... >, >,>, >, >, >, >, ~ ~ ~ ~ ~ ·e ·e e e "' "'"' "' "' "' "' r-. "" ,b ~ ~ _, _,_, _, _, _, _, s ii ~ s N ""'It ~o 6 ~ ... N Duration . . . . . ..................................................................... . . . . . . . . . . . . . . . . . . . . . . . . . . ............... ~.. . . . -. ' ........... " .................. .,_ . . . . . . . . . . . . . . . . . . . . . . . . •.•• ; ••..•....•• , ...... -1 ........... ; .. . . ............ ··'I···· >, >, "'"' _,_, ~s 2 5 10 25 50 100 200 500 1000 Average recurrence interval (years) NOAA Atlas 14. Volume 6, version 2 Created (GMT): Thu Mar 30 21:58:38 2017 Back to Top Page 2 of 4 Awrage recurrence tnte,val (years) -1 2 -5 -10 -25 -50 -100 -200 -500 -1000 -5-nwl -2-<lay -10-fflin -3-<lay ,~ -4-<lay -3o-mtn -7-<lay -60-fflin -10-<lay -2-hl -20-<lay -3-nr -30-day -5-nr -4!klay -12--N -60-day -24-« httn://hdsc.nws.noaa.l!ov/hdsc/ofds/ofds orintoal!e.html?lat=33.1501&lon=-117.3392&dat... 3/30/2017 Precipitation Frequency Data Server Maps & aerials ... 'Li Small scale terrain m MOUNTAIN Large scale map '£Clarit., y LOI C>AnlJel•s 01\19.,.lde 'OAnahelm Long Beacho Osnnta A)ia 100km _____ _,J0m1 ~urrieta EnHnada 0 Page 3 of 4 http://hdsc.nws.noaa.gov/hdsc/ofds/ofds orintoage.btml?lat=33.1501 &lon=-117 .3392&dat... 3/30/2017 Precipitation Frequency Data Server Back to Top us Department of Commerce National Oceanic and Atmospheric Administration National weather Service Nat,onal Water Center 1325 East West Highway Silver Spring, MD 20910 Questions?: HDSC auestions@ooaa.gov Disctaimer Page 4 of 4 http://hdsc.nws.noaa.gov/hdsc/pfds/pfds printpage.html?lat=33.l501 &lon=-117.3392&dat... 3/30/2017 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 San Diego County Hydrology Manual Date: · June 2003 Table 3-1 Section: Page: RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use Runoff Coefficient "C" Soil Type NRCS Elements Coun Elements %IMPER. A B Undisturbed Natural Terrain (Natural) Permanent Open Space O* 0.20 0.25 Low Density Residential (LDR) Residential, 1.0 DU/A or less 10 0.27 0.32 Low Density Residential (LOR) 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 (MOR) 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 (MOR) 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 (HDR) Residential, 24.0 DU/A or less 65 0.66 0.67 High Density Residential (HDR) Residential, 43.0 DU/A or Jess 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/Tndustrial (O.P. Com) Office Professional/Commercial 90 0.83 0.84 Commercial/Industrial (Limited J.) Limited Industrial 90 0.83 0.84 Commercial/Industrial General T. 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 0.41 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 will 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 3JO 9'0-N 3JO 8' 59" N N A Hydrologic Soil Group-San Diego County Area, California (1393 Sheridan Place) Map Scale: 1 :297 if JrtUd on A ~ ( 11" X 8.5") sheet. ~---=====~-----~'::=======~Me!Bs 0 4 8 ffi ~ ----.,,.------------~feet o 10 20 40 ro Map projection: W!b Meroltor c.omer andinales: WGS84 Edge tk:s: UTM Zone llN WGS84 Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 3/31/2017 Page 1 of 4 3JO 9'0-N 33" 8' 59"N Hydrologic Soil Group-San Diego County Area, California (1393 Sheridan Place) MAP LEGEND MAP INFORMATION Area of Interest (AOI) n Area of Interest (AOI) Solla Soll Rating Polygons D A D AID D B D BID D C D CID D D D Not rated or not available Soll Rating lines _,, A ,_, AID ,_, B _,, BID ,_,, C ,_, CID ,_, D --Not rated or not available Soil Rating Points • A • AID • B • BID Natural Resources Conservation Service ll C • CID • D a Not rated or not available Water Features Streams and Canals Transportation +++ Rails ,,,._, Interstate Highways _,w, US Routes --Major Roads 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 Hydrologlc Soll Group-Summary by Map Unit -San Diego County Area, California (CA638) Map unit symbol Map unit name Rating Acres inAOI 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 (AID, B/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 (AID, 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 ::iiiill Conservation Service Web Soil Survey National Cooperative Soil Survey 100.0% 100.0% 3/31/2017 Page 3 of4 Hydrologic Soil Group-San Diego County Area, California Component Percent Cutoff: None Specified Tie-break Rule: Higher Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 1393 Sheridan Place 3/31/2017 Page 4 of4 10.0 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 j 1 ti c1,0 ~0.9 ·10.s .:so.7 O.G 0.6 0.4 0.3 0.2 0. 1 r,.. ..... .......... " r,.. . " .., , ........ " r-.. • r", . l"'-·r,,. '""ro, , .. "' """' r,.. . I',. .... l'o,. """ . "" l"I" "'"' ~~~ .[", , • I" r-,l" ~ ,. ~~ .... • r,,, I', • I•~ . .... I' l"'~ ,.I" r,.. .... I", !"'or,. "' I"~~ .... "'I' • I", ~ "'• .... ""' ..... ... , ~ ~~ .. "· ··~ .... r,.. ·i-"'"" r.., • i-,. ·~ "'r,.. ~ r--.. i"' ~ l"~I" r,.,._ ""r-I"' ~ I", ""I"' "' I"~ •.. , .......... ,----r-· r--.... ,. .. ,...... ·r-.t--........ -r-,-,.,,i •. .:.!---..... ,.... -· I 5 6 7 8 9 10 15 20 30 Minutes 'I" I" 'I" ~ I" I"~ ' ~ ~ r~ . . . II 40 so Duration J I = I = Pe= D :: ' " f EQUATION 7.44 Pa 0-0.645 Intensity (in/hr) r 6-Hour Precipitation (in) Duration (min) r:,..., .... ~ .... "" r,,,, ... r--r,, ,. 1, ... I•"' I" ""', ' l" I' l"I" '" l•r, l'I" 1 ... , I" I"~ l"I" r,.. ' """ I" l"I" ~ r,.. ""~ ' I" ' I"'"' I r",""" I• l"I" '""" ""~ ~ • """' .. ... "'~ ' 'I" l"i-, """i-.. I" r .... , ~I" -- ' .,.,.,.,.,,., .,..,-.. ·-~., ., . ~i -..... ,__ - I ·-.... -i It.\ !II 2 3 4 5 6 Hours ± ~ ::p l 6.0 -· 5.5 fi 5.0 g 4.51 4.0 a, 3.5.!(!. 3.0 2.5 2.0 1.5 1.0 Intensity-Duration Design Chart M Template Directions for Appllcatfon: (1} From precipitation maps determine 6 hr and 24 hr amounts for the. selected frequency. These maps are included in the County Hydrology Manual (10, 50, and 100 yr maps Included in the Design and Procedure Manual). (2) Adjust 6 hr precipitation (if necessary) so tha1 It ls within the range of 45% to 65% of the 24 hr precipitation (not applicaple to Desert). (3) Plot 6 hr precipitation on the right side of the chart . (4) Draw a line through the point parallel to the plotted lines. (5) This line is the intensity-duration curve for the location being analyzed. Application Form: (a) Selected frequency ___ year . _!Ji (b)P5= _,n.,P24= -·P24"' (c) Adjusted P6<21 = __ in. (d) •x = ___ min. {e) I= __ in./hr. Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. :;~,fo"' --:: 1t t-l-i-~s..r. r-~.:\a. ...... 1---/---~t--+ .. f····l·s.is.. :-l .. : ....... , ·i1i la'.iahriI!!:v~~ l~ -:~~1-~t!~ll6Ht:~1-!l;J ~~-; il~l~l;tt~li~tI~t~tHi 1titii ~~:::::.:: ~:~~::t~:~f g:l~::~ 1~::!g::r~:!;T~:~ T~:-}~:: +:~:~: F G 3-!J Iii w LI. ~ w t) z ~ en i3 w fl) ~ ::, 0 t) 0::: w I-~ 0 EXAMPLE: Given: Watercourse Distance (D) = 70 Feet Slope (s) = 1.3% Runoff Coefficient (C) = 0.41 Overland Flow Time (T) = 9.5 Minutes SOURCE: Airport Drainage, Federal Aviation Administration, 1965 T = 1.8 (1.1"C) VD 3\fs (/J w I-::, z 20 ~ ~ w :ii: i== ~ 0 ...J LL 10 O 5 0::: w ~ FIGURE Rational Formula -Overtand Time of Flow Nomograph 3.3 EQUATION .6.E (1~~3)°.385 Feet Tc = 5000 Tc = Time of concentration (hours) L = W,atercoul"ff Distance (miles) 4000 .6.E = Change In elevation along effective slope tine (See Figure 3-S)(feet} 3000 60 3® 50 200 40 L Miles Feet 30 100 20 ' 18 3000 16 0.5 ' ' 14 2000 ' 12 ' 1800 ' 1600 ' 10 30 1400 ' 9 1200 8 20 7 6 5 10 4 3 300 5 200 .6.E L Tc SOURCE: California Division of Highways (1941) and l<irpich (1940) FIGURE Nomograph for Oetermlna1lon of Time of Concentration (Tc) or Travel Time (Tt) for Natural watersheds ~ Q) a. 0 en al jg Cf) -0 I +--1.5'---+-I l~=-01~1 --2% ___ n = .0175 -----...::.:~------! 2% Concrete Gutter Paved RESIDENTIAL STREET ONE SIDE ONLY 20 ""1-------i---.,--1---1--"'l""-,.T'"-11-T'"'"f'il~r-------r--~r-t---t--t-Tr 18-+--------11---,.--1----1---+..f'--+---t-+--+-+-""-16--l------h,::::,.==::j::::-...,J.._.JJ..__j~.J.--1--~1---.::::::::~ 10 -t------,.---it-----+----.f----+--+---1++--+--t----"''"<'· 9 -l----~c::::;::::::-.~--4--4+--J--l--JL..IHµ ___ ::::::..~q..---1--J+-_:::.~-1- a ---- 7-+--- 6 5 1.0 -+---.f'---------,1--+--1-......;::~; 0.9 -+~"'1«=------+-+--+--;-.;:,,,..c:t---ift--if-+-++-.....a:.i~----H'-----J 0.8 -+~'----~....,.---1'r#----+---t--+..P+..---l-+-++-#---;::...,,.---1-----:-,1--+---+--+ 0.7 -t:-,-------,,,i---...._ 0.5 2 3 4 EXAMPLE: Given: Q = 10 S,. 2.5% Chart gives: Depth = 0.4, Velocity = 4.4 f.p.s. 5 6 7 8 9 10 Discharge (C.F.S.} 20 30 40 50 SOURCE: San Diego County Department of Special District Services Design Manual FIGURE Gutter and Roadway Discharge -Velocity Chart ~ er 0 .E .... Q) 0.. Q) J!! .!: w c.. 0 ...J C/) EQUATION: V = 1.49 R213 s1'2 0.3 0.2 0.15 0.10 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 a: -a; ~ .!: Cl) ::, 0.01 ci 0.009 <! a: 0.008 (.) 0.007 ::J ::J 0.006 <! c::: 0.005 0 >- 0.00~~ I ~ 0.002 0.001 0.0009 0.0008 0.0007 0.0006 0.0005 0.0004 0.0003 n 0.2 0.3 0.4 0.5 0.6 ~ 0.8 "' 0.9 ~ 1.0 q6' "' "' 2 / ~~ ~ 3/ 4 5 6 7 8 9 10 20 > /' / "C C 0 / 0 Q) ti) .... Q) 0.. y., Q) ~ .£ ~ >-t- "g ...J w > GENERAL SOLUTION SOURCE: USDOT, FHWA, HDS-3(1961) Manning's Equation Nomograph ro t40 t 30 20 ~ 9 8 7 6 5 4 3 2 1.0 0.9 0.8 0.7 0.6 0.5 0.01 0.02 \)9'l-/ 9' C 0.03 . c Q) ·o l5 0.04 0 () Cf) Cf) w 0.05 z I (!) 0.06 ::J 0 a: 0.o7 0.08 0.09 0.10 0.2 0.3 0.4 FIGURE ~ 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, showirtg 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 (Table 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 uniform. 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 ,·' · l I , ~ ·1 l .. I ,/ •, r/ L.· Study Area LA 0 Define Study Areas (Two-Letter ID) © Define Maps (or Subregions on Region Basis) © Define Model Subareas on Map Basis ' ..... :·:~: .............. _.. ! , .... --' ' ,• ~#, ' .·· ' . ' . . . . 0 Define Major Flowpaths in Study Area © Define Regions on Study Area Basis Subarea ID= (LA010112) N~:: :===-···-_---~ Region#---1 Study Area (ID) #--l l _ © Define Model Nodes (Intersection of Subarea Boundaries with Flowpath Lines) GIS/Hydrologic Model Data Base Linkage Setup: Nodes, Subareas, Links LA 01 01 03 (j) Number Nodes IF ·~-USR El San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 22of26 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. Detennine P6 and P24 for the study using the isopluvial maps provided in Appendix B. If necessary, adjust the value for P 6 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: I. 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 MRJv1 for drainage areas up to approximately 1 square mile in size. If the watershed will significantly exceed 1 square mile then the NRCS method described in Section 4 should be used. The 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 Q1, T1, 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 T0; Q3, T3, and h 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 I3 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. Qr2, and Qu. 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., Qr1 = 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 (h/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 13 = 0. When T1 and T2 are the same, 11 and Ii are 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 = Q12 = 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 I 0%), use the shorter Tc for the intensity and the equation Q = :2:(CA)I. Note #3:. An optional method of determining the Tc is to use the equation Tc= [(I (CA)7.44 P6)/Q] us This equation is from Q = I:(CA)I = I:(CA)(7.44 Pr/Tc 645 ) 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