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HomeMy WebLinkAboutCT 16-10; HOME AVENUE; DRAINAGE STUDY; 2017-12-07J ~b ~ _ t 12,,·J i~ fl:r Nv~ -----DRAINAGE STUDY HOME AVENUE (CONDOMINIUM SUBDMSION) CITY OF CARLSBAD I<.ECORD COPY E_ 1-lii\1~ Initial Date JAN O 9 i018 . 'L, .. .,....NT r 11 G CT 16-10/PUD 16-12 DWG507-6A GR2017-0057 Prepared for: Edmond T. Shehab 800 Grand MMKLC, LLC 800 Grand Avenue, Suite C16 Carlsbad, CA 92008 Prepared by: bl-IA, Inc December 7, 2017 w.o. 1026-1383-400 TABLE OF CONTENTS Chapter 1-Discussion ............................................................................................................................... 3 Vicinity Map ................................................................................................................................... 3 Purpose and Scope ......................................................................................................................... 4 Project Description ........................................................................................................................ 4 Study Method ................................................................................................................................. 7 Summary of Results ....................................................................................................................... 8 Conclusions ..................................................................................................................................... 9 Declaration of Responsible Charge ........................................................................................... 10 Chapter 2-Exhibits .................................................................................................................................. 11 Existing Condition Hydrology Map ............................................................................................ 11 Proposed Condition Hydrology Map ......................................................................................... 11 Chapter 3 -Calculations .......................................................................................................................... 12 Existing Condition Hydrology Calculations ............................................................................... 12 100-Year Storm ............................................................................................................... 13 Proposed Condition Hydrology Calculations ............................................................................ 15 100-Year Storm ............................................................................................................... 16 Chapter 4 -Detention Routing ................................................................................................................ 19 Permeable Pavement BMP Detail .............................................................................................. 20 Chapter S -References ............................................................................................................................. 21 Methodology-Rational Method Peak Flow Determination .................................................... 21 HoME AVENUE CoNdoMiNiuMs CT 16~10/PUD 16~12 DRAiNAGE Srndy bl-tA, INC. ") L CHAPTERl DISCUSSION HOME AvENUE CoNdoMiNiuMs CT 16,10/PUD 16,12 DRAiNAGE Srudy bl-tA, INC. 3 L ~ VICINITY MAP HoME AVENUE CoNdoMiNiuMs CT 16.-10/PUD 16.-12 DRAiNA(iE Srndy bJ.tA, Inc. 4 L PURPOSE AND SCOPE The purpose of this report is to publish the results of hydrology and hydraulic computer analysis for the proposed Home Avenue Condominiums 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 systems considered as mitigation of any potential adverse effects of the proposed project. The mitigation measures proposed will include storm drains, energy dissipaters and permeable material to attenuate the effects of development on storm water discharge. The 100-year frequency storm will be analyzed. Information contained in this report will be referred to for the purpose of sizing treatment facilities as proposed in the associated Storm Water Quality Management Plan. PROJECT DESCRIPTION The Home Avenue Condominiums project is a 0.415-acre project that includes the development of five condominiums, an amenity site, a driveway, and surrounding landscape. The project is located at Home Avenue in the City of Carlsbad, west of the Interstate 5 freeway. The project site is bounded on the east by Hope Avenue and on the west by Jefferson Street. The project drains to one Point of Compliance (POC) located to the northwest corner of the project site. Treatment of storm water runoff from the site has been addressed in a separate report- "Priority Development Project (PDP) Storm Water Quality Management Plan (SWQMP) for Home Avenue Condominiums" by BHA dated September 27, 2017. 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. Pre-Development Conditions The existing site is approximately 0.415 acres and has been previously graded. The site is currently an impervious parking lot. Storm flows affecting the site are limited to the rainfall that lands directly on the property. Surface runoff sheet flows northwest across the parking lot to Home Avenue. Runoff that drains to Home Avenue will be conveyed northwest via existing curb and gutter to the storm drain system on Grand Avenue. Approximately 100% of the existing site is impervious. The on-site soil classification is Type B from NRCS Web Soil Survey. HoME AvENUE CoNdoMiNiuMs CT 16.-10/PUD 16.-12 DnAiNAGE Srndy bl-IA, Inc. 5 L Post-Development Conditions The project proposes the development of five (5) condominiums, an amenity site, a driveway, and surrounding landscape. Storm water runoff from the proposed project site is routed to a single POC located at the northwest of the project site. The proposed drainage pattern will be similar to the existing drainage pattern with some modifications to incorporate Best Management Practices (BMPs) into the project design to mimic the impacts on storm water runoff and quality. By incorporating BMPs, approximately 51 % of the developed site will be impervious. Runoff from the developed project site is drained to several onsite retention BMPs (pervious pavement and landscaping) for water quality purposes (the project is not subject to hydromodification requirements). The project also includes site design BMPs for additional pollutant control and to reduce runoff volumes. Once flows are routed via the proposed water quality and site design BMPs, all flows are then conveyed via storm drain to the aforementioned POC. The proposed driveway in the center of the project site will be designed as a retention BMP and will provide storm water treatment and flow detention. The BMP will include a permeable pavement surface layer and an infiltration storage layer below the surface to infiltrate runoff into subgrade soils. An underdrain pipe will be provided within the storage layer to convey high flows that exceed the infiltration capacity of the underlying soil. Patio areas in the back of the proposed residences will also be comprised of permeable pavement to minimize impervious area and provide additional stormwater retention. Roof drains will collect runoff from a portion of the impervious roof surfaces and discharge on the proposed permeable pavement driveway. Runoff from the proposed concrete sidewalks and landscape areas of the amenity site will also surface flow onto the permeable pavement driveway. The permeable pavement driveway will be gently sloped towards Home Avenue. High flows that exceed the infiltration capacity of the underlying soil will be drained through an underdrain pipe, which will outlet over rip rap in a landscape area and flow northwest to the project's point of discharge at POC-1. Roof runoff that is unable to flow to the permeable pavement driveway will be directed to the back of each residence. The landscape areas will consist of native or drought tolerant landscape to promote water retention. Roof downspouts will discharge over rip rap to the relatively flat pervious areas to facilitate sheet flows and minimize runoff velocities, thereby improving storm water treatment. These areas are also designed to reduce the impervious footprint of the project site. Flows from the landscape areas that exceed the infiltration capacity of the subgrade soils will drain via yard drains onto Home Avenue. All other areas HoME AvENuE CoNdoMiNiuMs CT 16..-10/PUD 16..-12 DRAiNAGE Srudy bJ-iA, INC. 6 L the proposed residences will flow directly onto Home Avenue at POC-1. The proposed drainage patterns will not alter the existing flow pattern and will discharge from the site at the historic discharge points. 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 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 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 P6 for 100-year storm, see References. I = 7.44x(P6)x(Tc)"0·645 P6 for 100-year storm =2.6" 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]). HoME AvENUE CoNdoMiNiuMs CT 16;10/PUD 16;12 DnAiNAGE STUdy bkt\, INC. 7 L For all landscape areas, a runoff coefficient assuming 0% impervious was used based on the underlying soil type, 0.25 for Type B soils. All roof and concrete sidewalk areas were considered 95% impervious, and assigned a runoff coefficient of 0.87. The Proposed Condition Hydrology Map shows the proposed on-site drainage system, on- site subareas, and nodal points. Table 1 below summarizes the composite C-values calculated in the existing and proposed conditions. TABLE 1-Weighted Runoff Coefficient Calculations Existing Condition Hydrology-Home Avenue Up Node Down Node Total Acreage C1 Al (acres) C2 A2 (acres) Ccomp 1 3 0.42 0.25 0.00 0.87 0.42 0.87 Developed Condition Hydrology-Home Avenue Up Node Down Node Total Acreage C1 Al (acres) C2 A2 (acres) Ccomp 10 11 0.05 0.25 0.03 0.87 0.02 0.49 11 12 0.24 0.25 0.11 0.87 0.13 0.59 12 13 0.02 0.25 0.01 0.87 0.01 0.59 15 13 0.06 0.25 0.02 0.87 0.04 0.63 16 13 0.05 0.25 0.03 0.87 0.03 0.56 Note: C-values taken from Table 3-1 of the San Diego County Hydrology Manual, consistent with on-site existing soil types. SUMMARY OF RESULTS Table 2 below summarizes the pre and post-development drainage areas and resultant 100- year peak flow rates at POC-1 from the project site. TABLE 2-Summary of Peak Flow Results for POC-1 Drainage Area (acres) 100-Year Peak Flow (cfs) Pre-Developed Condition 0.42 2.37 Post-Developed Condition 0.42 1.27 DIFFERENCE 0.00 -1.10 The developed site contains a permeable pavement driveway and other permeable surfaces to treat and detain runoff generated by the impervious surfaces of the project site. The detention values for the permeable pavement BMP has not been quantified, due to the fact that enough detention is achieved by decreasing and disconnecting impervious surfaces. Runoff values have been effectively mitigated to below historical values without considering additional flow detention and infiltration capacity. Therefore, we consider the detained HOME AVENUE CoNdoMiNiuMs CT 16--10/PUD 16--12 _____ D_n_A_iN_A_:G_E_S_rn_d...;..y ________________________ b_l-t_A_,,'--ln_c_. ___.i87_ flowrate results presented in this Report to be conservative in nature, as the permeable pavement BMP mentioned above will likely further mitigate the site runoff beyond the values shown. Since pre-development 01110 (2.37 cfs) is equal to or greater than post-development 0100 (1.27 cfs), this system achieves the goal of attenuating the storm flows from the proposed development to pre-development levels. CONCLUSION As shown in Table 2, the development of the Home Avenue Condominiums project will result in a net decrease of peak flow discharged from the project site by approximately 1.1 cubic feet per second. The proposed drainage basin matches the existing drainage basin in terms of overall area and drainage conditions. Drainage patterns reflected on the Proposed Condition Hydrology Map will decrease the total developed runoff due to a decrease in impervious surfaces. By increasing the overall time of concentration and implementing permeable pavements, the rate of discharge between the existing condition and the developed condition can be directly discharged from the site without any further handling. All developed runoff will receive water quality treatment in accordance with the site specific SWQMP. The required treatment areas are based on the City of Carlsbad BMP Design Manual. 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 O,oo 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. HOME AvENUE CoNdoMiNiuMs CT 16,10/PUD 16,12 DnAiNAGE Srudy bl-tA, INC. 9 L 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 City of Carlsbad is confined to a review only and does not relieve me, as Engineer of Work, of my responsibilities for project design. Ronald Holloway R .C.E. 29271 HOME AVENUE CoNdoMiNiuMs CT 16;10/PUD 16;12 DRAiNAGE Srndy /-'8✓16 Date M-tA, INC. 10 L CHAPTER2 EXHIBITS Existing Condition Hydrology Map & Proposed Condition Hydrology Map HOME AvENUE CoNdoMiNiuMs CT 16,10/PUD 16,12 DRAiNAGE Srudy M-tA, Inc. 11 L 10· 5' o· 10· ;" \ \ '! \'. r j J // /; } / SCALE: 1" = 1 0' 20' 30' '; ' . r\ , \ \.__r-::--! / / ! \__: /'1 . ' l i \' i ' ' ' . "' (\ I \ ! < I I I I I ' \ I ~;\ , , l \....\ 1 -; I ! I 1. ! ~) ,,../ I ,f"' <' ;'( ' './ / i \ ' ' \ EXISTING CONDITION HYDROLOGY MAP HOME AVENUE CONDOMINIUMS rJ \ SA) ~ \ / I I +s-o;'G·., "' @ C=0.87 I ' ,j I v ' PROPERTY UN£ [ ____ _ / / r 1'\ i ' ' I' I i \ I ; '' " I! !i ii ii " '! ~ I I : r \ . i \ ; /1 "·· / i ,, i ii f ' ' ' ; "'ti (1 I ' ' ' fl' -\ n /1 .. ' I ( i ' l J < ~r n /\ ; ' I \ PROPERTY LINE j I I Ii , -··--f--.. ,- ! ' i -L._ ' --' !L ·' t ~ i :~ j ! \' i --- \\ .,/··1•--1 \:\ --~L__))i ~~ "' ; ... ,_,____,,_, \/ CT 16-10/PUD 16-12 PROJECT CHARACTERISTICS PARCEL AREA APN SOIL TYPE DEPTH TO GROUNDWATER LEGEND SURFACE NODE SURFACE FLOW. 100 YEAR BASIN AREA RUNOFF COEFFICIENT BASIN BOUNDARY BASIN SUB-BOUNDARY PROPERTY LINE FLOW LINE bi-lA,lnc. kind planning, civil engineering, suiveytng 5115 A VEN I DA ENCINAS SUITE "L" CARLSBAD, CA. 92008-4387 (760) 931-8700 0.415 ACRES 203-202-03 B 16.5 FEET SYMBOL @!) C=0.87 ----- . . .. _______,... ... -. EXISTING CONDITION HYDROLOGY MAP HOMEAVENUE CONDOMINIUMS CARLSBAD, CA CT 16-10/PUD 16-12 SHEET 1 OF 1 / ·-----' \ ('_, ... ,J l \..J 1. ! / 1 o' 5' o' 1 o' 20' 30' SCALE: 1" = 10' ,- I l ! I Y I ) I j I \J {,P I ' 0 11 /~ I I(\ I , '-' I I 1t / I\ I / \i I ~I /< • ' I \,_, /] _II) ~ ' ' i I !q ,I ~ , '\I\. '¥ \ . \ I l~~c I, /1 r 1' I 1 \J 'I I ! l 'N (U //'; ' f /}( ( • I /f I PROPERTY\d1NE +s > ·✓ , I I ; I ' I \j ( I II )/ I I 11 \J (I I ';;/ I r I I ~' II ' ' \, \ > I ~\i >-I I cY i r1 >I, \J ) " I\ \ \ '~ .. (\ •~ I 1"'-I \.)I I ii \11 (11· ' ' >i ( ' ~ ; I, \~ ( / ~ I 'I )1 ' I, I , I •• I \,,I (I >ti r ! I ~ , . I \ \ i "' "' I ! "' ' "' "'! t "' J 'V '¥ "' "' "' "' 1 :1? 'V ) ' 'V 1 ~ \"\ ' 'V \ ) ! ) / I ,, !\ 11 ' ' ' 1/ : I'\ I a \ • 1, .• ' I I i "' PROPOSED CONDITION HYDROLOGY MAP HOME A VENUE CONDOMINIUMS I I \ \ I ~ ' I I \~ \ I / \ ----+-\ ! \ I ' ' ' \ I I - I 'V 'V 'V t 0 --- r --------- I I I = I I I I = I I __ -, - - __ -, __ -, I I L ------7-----,-J "' c:, >':: o2 ~ I I J --'I t - r--_ I I ' ' . ' .. "/ ' y_·I I , i==:Jr:"'==tt I I - - ' / , ! I I V I FUTURE AMENI TY SITE ' \ I I . I I I ' 't 'V "' 'V \"' ' ' 0.05 C=0.56 1// ' 4, ' ' 'V ' ' ' ' !., ' ' ' \ k k I • I I I P OPERTY LINE I I I I ' \ I I 1/ ) /------ / / // . / .,-., 'V "' 'V 'V '¥ '-_L:;;,, __ /~~ PROPERTY LINE CT 16-10/PUD 16-12 LEGEND PROPERTY LINE POINT OF CONCENmA TION FLOW DIRECTION LANDSCAPE CONCRETE TURF BLOCK, PERVIOUS RIP RAP ENERGY DISS/PATER PROPOSED PERMEABLE PAVEMENT BMP (POLLUTANT CONmOL) SYMBOL @ @§) C=0.49 ----- POC-1 PROJECT CHARACTERISTICS PARCEL AREA 0.415 ACRES DISTURBED AREA 0.415 ACRES PROPOSED IMPERVIOUS AREA 0.214 ACRES PROPOSED PERVIOUS AREA 0.202 ACRES SOIL TYPE B DEPTH TO GROUNDWATER 16.5 FEET WEIGHTED RUNOFF COEFFICIENT TABLE Developed Condition Hydrology-Home Avenue Up Node Dow n Node Tot al Acreage c, Al (acres) c, A2 {acres) Ccomp 10 11 0.05 0.25 0.03 0.87 0.02 0.49 11 12 0.24 0.25 0.11 0.87 0.13 0.59 12 13 0.02 0.25 0.01 0.87 0.01 0.59 15 13 0.06 0.25 0.02 0.87 0.04 0.63 16 13 0.05 0.25 0.03 0.87 0.03 0.56 Note: C-va I ues ta ken from Table 3-1 of the San Di ego County Hydro I ogy Ma nua I, consistent with on-site existing soil types. SUMMARY OF PEAK FLOW RESULTS FOR POC -1, 2 & 3 AREA CON mlBUTING TO: POC-1, 2 & 3 PERMEABLE CONCRETE PAVERS 2• BEDDING LA YER AASHTD /8 12• RESERVOIR LA YER AASHTO #2 or j3 FILTER LA YER AASHTO /8 PRE -DEV. AREA PRE-DEV. PEAK (ACRES) FLOW {CFS) 0.415 2.37 JOINT 6' PERFDRA TED PVC PIPE SUBGRADE PERMEABLE PAVEMENT BMP DETAIL NOT TD SCALE b~A,lnc. POST-DEV. AREA (ACRES) 0.415 . ~ . . •· .. - .0 ' 04 " 4 . ~---. •· POST-DEV. PEAK FLOW CURB (CFS) 1.27 ADJACENT MATE/I/Al J ' INFIL TRA TIDN STORAGE LAYER PROPOSED CONDITION HYDROLOGY MAP land planning, cMI englnee~ng, surveying HOMEAVENUE CONDOMINIUMS CARLSBAD, CA 5115 AVENIDA ENCINAS SUITE "L" CARLSBAD , CA. 92008-4387 (760) 931-8700 CT 16-10/PUD 16-12 SHEET 1 OF 1 CHAPTER3 CALCULATIONS Existing Condition Hydrology Calculations HoME AVENUE CoNdoMiNiuMs CT 16.-10/PUD 16.-12 DRAiNAGE STUdy bJ.tA, Inc. 12 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 Engi neering 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 Hydrology Study * 100-Year Storm * Home Avenue ************************************************************************** FILE NAME : 1383El00.DAT TIME/DATE OF STUDY: 09:57 09/26/2016 USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION: 2003 SAN DIEGO MANUAL CRITERIA USER SPECIFIED STORM EVENT(YEAR) = 100 .00 6-HOUR DURATION PRECIPITATION (INCHES) = 2.600 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 ANALYS I S *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* * * * HALF-CROWN TO STREET-CROSSFALL : CURB GUTTER-GEOMETRIES: MANNI NG WIDTH CROSSFALL IN-/ OUT-/PARK-HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) 1 30 .0 20.0 0 .018/0.018/0 .020 0.67 2 .00 0 .0313 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 1. Relative Fl ow-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 I S CODE = 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< ================================================---===========------------== *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT = .8700 S.C.S. CURVE NUMBER (AMC I I) = 0 I NI TIAL SUBAREA FLOW-LENGTH(FEET) = 66.00 UPSTREAM ELEVATION(FEET) = 59.25 DOWNSTREAM ELEVATION(FEET) = 58 .00 HOME AVENUE CoNdoMiNiuMs CT 16--10/PUD 16--12 DRAiNAGE Srndy bl-IA, Inc. 13 L ELEVATION DIFFERENCE(FEET) = 1 .25 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 100 YEAR RAINFALL INTENSITY(INCH/HOUR) NOTE: RAINFALL INTENSITY IS BASED ON Tc SUBAREA RUNOFF(CFS) 0.36 2 . 718 6.850 = 5-MINUTE. TOTAL AREA(ACRES) = 0 .06 TOTAL RUNOFF(CFS) = 0 .36 **************************************************************************** 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) = 58.00 DOWNSTREAM(FEET) CHANNEL LENGTH THRU SUBAREA(FEET) = 128.00 CHANNEL SLOPE CHANNEL BASE(FEET) 50 .00 "Z" FACTOR = 20.000 MANNING 'S FACTOR= 0 .015 MAXIMUM DEPTH(FEET) = 1 .00 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6 .572 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .8700 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 .03 TRAVEL TIME(MIN .) Tc(MIN.) = 5 .33 1. 38 0 .82 2.61 0 .35 SUBAREA AREA(ACRES) AREA-AVERAGE RUNOFF COEFFICIENT SUBAREA RUNOFF(CFS) 0.870 TOTAL AREA(ACRES) = 0 .4 PEAK FLOW RATE(CFS) END OF SUBAREA CHANNEL FLOW HYDRAULICS : DEPTH(FEET) = 0 .04 FLOW VELOCITY(FEET/SEC.) 56.94 0.0083 2 .03 2 .37 LONGEST FLOWPATH FROM NODE 1.00 TO NODE 1. 09 3 .00 = 194 .00 FEET. ==================================================================-=======-= END OF STUDY SUMMARY: TOTAL AREA(ACRES) PEAK FLOW RATE(CFS) 0 . 4 TC (MIN. ) = 2 .37 5 .33 ===================================================-=-=====-----==----====-- ===========================================================---====-----===-- END OF RATIONAL METHOD ANALYSIS HoME AvENUE CoNdoMiNiuMs CT 16.-10/PUD 16.-12 DRAiNAGE Srudy bliA, Inc. 14 L CHAPTER3 CALCULATIONS Proposed Condition Hydrology Calculations HOME AvENUE CoNdoMiNiuMs CT 16~10/PUD 16~12 DRAiNAGE Srndy M-tA, 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************************** * Proposed Hydrology Study * 100 Year Storm * Horne Avenue ************************************************************************** FILE NAME: 1383HOMP .DAT TIME/DATE OF STUDY : 11:15 09/26/2017 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 .600 SPECIFIED MINI MUM 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 MODEL* * * * HALF-CROWN TO STREET-CROSSFALL : CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSSFALL I N-/ OUT-/PARK-HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n) 1 30.0 20.0 0 .018/0.018/0.020 0.67 2 .00 0 .0313 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 = .5000 S .C.S. CURVE NUMBER (AMC II) = 0 INITI AL SUBAREA FLOW-LENGTH(FEET) = 46.00 UPSTREAM ELEVATION(FEET) = 59 .80 DOWNSTREAM ELEVATION(FEET) = 59.25 ELEVATION DIFFERENCE(FEET) = 0 .55 HoM E AvENUE CoNdoMiNiuMs CT 16.-10/PUD 16.-12 DnAiNAGE Srudy M-1A, Inc. 16 L SUBAREA OVERLAND TIME OF FLOW(MIN .) = 100 YEAR RAINFALL INTENSITY(INCH/HOUR) SUBAREA RUNOFF(CFS) 0 .14 6 .901 5.565 TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) 0.14 **************************************************************************** FLOW PROCESS FROM NODE 11. 00 TO NODE 11.00 IS CODE= 81 ---------------------------------------------------------------------------- >>>>>ADD ITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< -==---------===----========================================================= 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5 .565 *USER SPECI FIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .5900 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT= 0 .5745 SUBAREA AREA(ACRES) 0.24 SUBAREA RUNOFF(CFS) TOTAL AREA(ACRES) = 0 .3 TOTAL RUNOFF(CFS) = TC(MIN.) = 6.90 0 .79 0.93 **************************************************************************** FLOW PROCESS FROM NODE 11. 00 TO NODE 12 .00 IS CODE= 41 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRO SUBAREA<<<<< >>>>>USING USER-SPECIFIED PIPESIZE (EXISTING ELEMENT)<<<<< ====----=======-============================================================ ELEVATION DATA: UPSTREAM(FEET) = 57.83 DOWNSTREAM(FEET) FLOW LENGTH(FEET) = 120.00 MANNING 'S N = 0 .011 DEPTH OF FLOW IN 8.0 INCH PIPE IS 4.9 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 4.18 GIVEN PIPE DIAMETER(INCH) = 8 .00 NUMBER OF PIPES PIPE-FLOW(CFS) = 0.93 PIPE TRAVEL TI ME(MIN.) = 0.48 LONGEST FLOWPATH FROM NODE Tc (MIN.) = 10.00 TO NODE 7.38 12 .00 1 56.70 166.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 12.00 TO NODE 13.00 IS CODE= 51 >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRO SUBAREA (EXISTING ELEMENT)<<<<< ====-==========--=========================================================== ELEVATION DATA: UPSTREAM(FEET) = 56.70 DOWNSTREAM(FEET) CHANNEL LENGTH THRO SUBAREA(FEET) = 22 .00 CHANNEL SLOPE CHANNEL BASE(FEET) 5 .00 "Z" FACTOR= 5 .000 MANNING 'S FACTOR= 0 .030 MAXIMUM DEPTH(FEET) = 1.00 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5 .207 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .5900 S.C.S. CURVE NUMBER (AMC II) = 0 TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) 0 .96 56.39 0 .0141 TRAVEL TIME THRO SUBAREA BASED ON VELOCITY(FEET/SEC.) AVERAGE FLOW DEPTH(FEET) 0 .12 TRAVEL TIME(MIN.) 1. 36 0.27 Tc(MIN.) = 7.65 0.02 SUBAREA AREA(ACRES) AREA-AVERAGE RUNOFF COEFFICIENT TOTAL AREA(ACRES) = 0.3 SUBAREA RUNOFF(CFS) 0.575 PEAK FLOW RATE(CFS) END OF SUBAREA CHANNEL FLOW HYDRAULICS: DEPTH(FEET) = 0 .12 FLOW VELOCITY(FEET/SEC.) LONGEST FLOWPATH FROM NODE 10.00 TO NODE 1. 32 13.00 = 0.06 0 .93 188.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 13.00 TO NODE >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<< HoME AvENUE CoNdoMiNiuMs CT 16~10/PUD 16~12 DRAiNAGE STUdy 14.00 IS CODE= 51 bl-IA, Inc. 17 L >>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 56.39 DOWNSTREAM(FEET) 56.27 CHANNEL LENGTH THRU SUBAREA(FEET) = 6.00 CHANNEL SLOPE 0 .0200 CHANNEL BASE(FEET) = 3.30 "Z" FACTOR= 1.000 MANNING 'S FACTOR= 0.015 MAXIMUM DEPTH(FEET) = 0.50 CHANNEL FLOW THRU SUBAREA(CFS) = 0.93 FLOW VELOCITY(FEET/SEC.) = 2 .84 FLOW DEPTH(FEET) = 0.10 TRAVEL TIME(MIN.) = 0 .04 Tc(MIN.) = 7.68 LONGEST FLOWPATH FROM NODE 10.00 TO NODE 14.00 194 .00 FEET . **************************************************************************** FLOW PROCESS FROM NODE 15.00 TO NODE 14.00 IS CODE= 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 100 YEAR RAINFALL I NTENSITY(INCH/HOUR) = 5 .192 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT= .6300 S .C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT= 0 .5843 SUBAREA AREA(ACRES) 0 .06 SUBAREA RUNOFF(CFS) TOTAL AREA(ACRES) = 0 .4 TOTAL RUNOFF(CFS) = TC(MIN .) = 7.68 0.20 1.12 **************************************************************************** FLOW PROCESS FROM NODE 16.00 TO NODE 14.00 IS CODE= 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5 .192 *USER SPECIFIED(SUBAREA): USER-SPECI FIED RUNOFF COEFFICIENT= .5600 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT= 0.5814 SUBAREA AREA(ACRES) 0 .05 SUBAREA RUNOFF(CFS) TOTAL AREA(ACRES) = 0.4 TOTAL RUNOFF(CFS) = TC(MIN.) = 7.68 END OF STUDY SUMMARY : TOTAL AREA(ACRES) PEAK FLOW RATE(CFS) 0. 4 TC (MIN.) = 1. 27 END OF RATIONAL METHOD ANALYSIS HoME AvENuE CoNdoMiNiuMs CT 16,10/PUD 16,12 DnAiNAGE Srndy 7.68 0 .15 1. 27 b~A, Inc. 18 L CHAPTER4 DETENTION ROUTING HoME AvENUE CoNdoMiNiuMs CT 16,10/PUD 16,12 DnAi NAG E S rndy b J.t A, Inc. ~. _______________________________ : 19 L- PERMEABLE PAVEMENT BMP DETAIL PERMEABLE CONCRETE PAVERS 2 H BEDDING LA YER AASHTO j8 12• RESERVOIR LAYER AASHTO #2 or j3 ALTER LAYER AASHTO /8 6" PERFORA TEO PVC PIPE SVBGRAOE PERMEABLE PAVEMENT BMP DETAIL NOT TO SCALE HOME AvENUE CoNdoMiNiuMs CT 16;10/PUD 16;12 DRAiNAGE Srudy ... : ·~· . .,. CURB ADJACENT MATERIAL 3• INAL TRA TlON STORAGE LA YER bl-IA, Inc. 20 L CHAPTERS REFERENCES Methodology -Rational Method Peak Flow Determination HOME AVENUE CoNdoMiNiuMs CT 16,10/PUD 16,12 DnAiNAGE Srndy bHA, Inc. 21 L NOAA's National Weather Service Hydrometeorological Design Stud '··" Ce Precipitation Frequency Data Server {Pf p L..,. __ __,i (!) NWS O All NOAA~ • General Information Homepage Progress Reports FAQ Glossary Precipitation Frvquency Data Server GIS Grids Map$ Time Series Temporals Documents Performance, Probable Maximum Procipitation Documents Miscellaneous Publlcn.tiO!lS Storm Analysis Record Precipitation Contact Us lnquiriu List--serve, Soarch NOAA ATLAS 14 POINT PRECIPITATION FREQUENCY ESTIMATES: CA Data description oat. type: !Precipitation depth v j Units: i English vj nme .. ries type: !Partial duration vi Select location 1) Manually: 1) By location (decimal degrees, use"·" for Sand W): Latitude: Longitude; b) By sbltion (list of CA stations): i.:I S:.;e:.;le:.;c:.;t .;;•t:::a:::tio;;;n.:._ ____________ v..:..J! c) By address ('--'Se.;.•;..rm;..... ________ __Jlc__O.~I 2) Use map (if ESRI interactive map is not loading, try adding the host: https:l/js.1rcgls.corn/ to the firewall, or contact us at hdsc.questions@noaa.gov): ~ ~ ~..,, I ., ! PF tabular Duration 1 ~ 0.137 (0.115-0.1&4) 0.196 . (0.165-0.235) ~ 0.237 (0.199-0.264) 0.335 In (0.282-0.402 a 0."50 (0.378-0.540) G 0.606 10.510-o.n7) 0.710 r (0.598-0.852) B 0.911 (0.767-1.09) ~ 1.1-4 I v'' \ ~. ,\ POINT PRECIPITATION FREQUENCY (PF) ESTIMATES Wtni 90% CONFIDENCE INTERVALS AND SUPPLEMENTARY INFORMATION NOAA Atlas 14, Volume 6, Version 2 PF graphical Supplementary information / a) Select location Move crosshair or double ciick b) CIiek on station icon , ~ 0 Show stations on map \ Location lnfonnatlon: Name: Carlsbad, California, USA• Latitude: 33.1633' Longitude: •117.3461" Elevation: 60.64 ft .. • Source: ESRI Maps -•• Source: USGS ~ Prlntpage PDS-based precipitation frequency estimates with 90% confidence Intervals (In inches)1 2 5 10 100 200 500 1000 0.173 0.22-4 0.<4<43 0.505 0.597 0.6U (0. 146-0.208) (0.188-0.270) (0.338-0.586) (0.374-0.689) (0.423-0.851) (0.460-0.997) 0.2-48 0.634 0.72-4 0.856 0.966 (0.209-0.296) (0.484-0.6-40) (0.537-0.968) (0.606• 1.22) (0.680-1.43) 0.300 °'767 0.876 1.03 1.17 (0.252-0.361) (0.588-t.01) (0.&49-1.20) (0.733-1.48) (0. 796-1. 73) 0.-425 0.550 1.09 1.2-4 U 7 1.65 0.357-0.511) 0.461-0.663 0.829·1.« (0.918-1.69) 1.()4-2.09 t.13-2.44 0.570 0.738 1.-46 1.66 1.96 2.22 (0.479-0.685) (0.616-0.889) (t.11-1.93) (1.23-2.27) (1.39-2.80) (1.51-3.28) 0.75-4 0.960 1.61 1.S. 2.09 us 2.75 (0.834-0.906) (0.805· 1.16) (1.26-2.07) (1.40-2.43) (t.54-2.&4) (1.74-3.49) (1.88-4.07) 0.862 1.12 1.85 2.11 2.38 2.78 3.12 (0.741-1.06) (0.938-1.35 (1.45-2.39) (1.61-2.79) (1.77-3.25) (t.97-3.97) (2.13-Ht) 1.1-4 U-4 2.35 2.66 2.99 3.-45 3.82 (0.955-1.37) (t.21-1.74) (1.85-3.04) (2.03-3.52) (2.21-4.07) (2.«·4.92) (2.61-5.88) u s 1.86 3.03 3.-40 3.78 -4.31 -4.72 L_ n (0.957-1.36) (2.14-3.36) (2.37-3.90) (2.59-4.50) II (2.80-5.18) (3.05-8.14) (3.23-8.99) E ll 1.38 3.39 3.8' 4.30 II 4.76 5.40 5.88 (1.22-1.60) 2.88-4.09) (3.18-4.73) (3.48-5.41) (376-<l.18) (4.09-7.26) (4.32-8.18) I 2-day II 1.68 2.90 4.21 4.78 5.35 II 5.94 6.74 7.35 (1.48-1.94) (2.55-3.37) (3.56-5.08) (3.96-5.88) (4.33-6.74) (4.69-7.69) (5.11-9.06) (5.39-10.2) B 1.88 2.48 3.26 5.41 6.08 6.77 7.69 8.41 (1.88-2.17) (2.18-2.87) 2.88-3.78 (4.48-6.88) (4.92-7.88 (5.34-8.75) 5.84-10.4 8.18-11.7) I •-day I 2.04 2.69 3.55 5.94 6.69 7.46 8.51 9.32 (1.80-2.36) (2.37-3.12) (3.12-4. (4.92-7.32) (5.42-8.43) (5.88-9.65) (6.45-11.4) (6.84-13.0) B 2.36 3.13 4.16 7.07 7.99 8.95 10.3 11.3 (2.06-2.73) (2.76-3.63) (3.88-4. (5.88-8. 70) (6.47-10.1) (7.06-11.6) (7.78-13.8) (8.26-15.7) 110-day I 2.81 3.49 4.66 9.08 10.2 11.7 13.0 (2.30-3.02) (3.08-4.04) (4.10-5.41) (7.35-11.4) (8.04-13.2) (8.90-15.8) (9.51-18.0) 20-day 3.19 4.30 11.7 13.2 15.4 17.1 (2.82-3.69) (3.79-4.98) (9.48-14.7) (10.5-17.1) (11.7-20.7) (12.6-23.8) 30-day 3.76 5.09 14.2 16.2 18.9 21.1 (3.32-4.35) (4.49-5.89) (11.5-17.9) (12.7-20.9) (14.3-25.5) (15.5-29.4) I ·~•YI 4.45 6.02 17.1 19.6 23.1 26.0 (3.93-5.15) (5.30-6.97) (13.9-21.8) (15.5-25.3) (17.5-31.1) (19.1-36.1) i so~,y II 5.14 6.91 19.9 II 22.8 27.1 30.6 (4.53-5.94) 8.09-8.00 (18.1-25.0) (18.0-29.5) (20 5-364) 22.4-42.5 1 Precipitation frequency (PF) estimates In this table are based on frequency analysis of partial duration series {POS). Number'$ In parenthestS are PF estimates at lower and upper bounds of the 90% confldence Interval. The probability that precipitation frequency estimates (for a given duration and average recurrence lntervaQ 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, Estimates from the table in CSV fom,at: i Precipitation frequency estimates v ! Submit US Depurtm(:nf ol Comrne•c.'t.l Nait0na1 Oct1rmlc an:J AtlllOsphcric Adnlfnislrutioo Noti,mul Weatti~r SEJrY1C'~ 011ice ol Wt1:lt:r Pr~dktiou (OW'PJ 1325 Eat.t WolJ! H1ijhWU)' SiNer Spdng, MD 20910 Pag4' A11thc>r: HOSC webmasler Par,t'! bu,t 1ni><M'ied: April :?I 2017 Main Link Categories: Home I OVVf' Mup Ohu.:ft11irner Olsc!ll!rrwr Crcditt. Glusirnry Privacy Poli About 1 Cnrcer Opportuniti San Diego c ·ounty Hydrology Manual Date: · June 2003 Table 3-1 Section; Page: RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use I Runoff Coefficient "C" Soil Type NRCS Elements Coun Elements %IMPER. A B Undisturbed Natural Terrain (Natural) Permanent Open Space 0* 0.20 0.25 Low Density Residential (LOR) Residential, 1.0 DU/A or Jess 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 (MDR) Residential, I 0.9 DU/ A or less 45 0.52 0.54 Medium Density Residential (MOR) Residential, 14.5 DU/A or Jess 50 0.55 0.58 High Density Residential (HOR) Residential, 24.0 DU/A or less 65 0.66 0.67 High Density Residential (HDR) 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/lndustrial (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 I.) 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.J .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 San Diego County Hydrology Manual Date: June 2003 C = 0.90 x (%Impervious)+ Cp x (1 -% Impervious) Section: Page: 3 5 of26 Where: 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 detennined 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 . -.. . 'o ••• ., ' . , .... ' : : / 1/ ~ \ ... \ \ \ . / / -: '\ -'. . \ ~ ;;:-~ r . ,, ~ ' ,, / / ' ,'It • ' \ .. ' ,,_ '•. ., . ~..ie , /<~ " ' '# . ~e • -_., \ +o ... "'Y ,,,. ·, . -/, _,, \ / .,, .. " \ ,,,. '• \ , , \ ~ \ ; \ ' •' ~ > / ,,,, ., -~ ,, ' ,f -'' /. ' .. ,, .. \ ti-ti -', I • \. \ \ ' -V {'-)~ .. • .. , t'-l_.. / ..ie .ro '\. ' ./ ~~ ~ : " '\.\ -_/,.,, ci~ ('9! , ~ ,, . ' ~ ' ' •U .. , ~ < • • ;11 . ~ . . ... I . . .. -. = Hydrologic Soil Group-San Diego County Area, California MAP LEGEND MAP INFORMATION ArH of lnt-t (AOI) D Area of Interest (AOI) Soils Soll Ratint ll'olygoM D A A/0 • B • BIO D C l!!I C/0 D D D Not rated Of not IVailatlle SollRatlllfllMe -A -A/0 -B -BIO -C -C/0 -D -,, Not rated Of not available Soll Ratint ll'elnts ■ A ■ A/0 ■ B ■ BID NaturalRNOUl'CN Conservation SeNtee ■ C ■ C/0 ■ D a Not rated Of not available WallfFe.- .,...._, Streams and Canals T~ +++ Rails ,,..., ~ Highways ,,..., US Routes "-' MajOl'Roadl -Local Roads 11ac11..-- • 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 deta~ of mapping and accuracy of soil line placement. The maps do not show the smaN 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 'Nib Soil Surtey URL: hftp://Websoilsurvey.nrcs.usda.gov Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil SUfVey 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 USOA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Survey Area Data: San Diego County Area, California Version 9, Sep 17, 2015 Sow map units are labeled (as space allows) for map scales 1 :50,000 or larger. Oate(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. 8/1 9/2016 Page 2 of 4 Hydrologic Soil Group-San Diego County Area, California Hydrologic Soil Group Hydrologic Soil 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 1.2 sand, 2 to 9 percent slopes Totals for Area of Interest 1.2 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, BID, and CID). 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, BID, or CID), 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 Component Percent Cutoff: None Specified USDA Natural Resources :iiliiliiiii Conservation Service Web Soil Survey National Cooperative Soil Survey 100.0% 100.0% 8/19/2016 Page 3 of 4 Hydrologic Soil Group-San Diego County Area, California Tie-break Rule: Higher Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 8/19/2016 Page 4 of4 t:i UJ LL ~ w u z ~ i5 UJ (/J ~ :::> 0 (.) C! LU i 1001 ,.s I H/t✓✓ ✓ 1. (/J LU I-::, z 0 20 ~ ~ UJ :i: .== ~ 0 ...J LL 10 ~ :5 C! w 6 ---0 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 Administration, 1965 FIGURE Rational Formula -Overfand Time of Flow Nomograph 3.3 ~E Feat .~E 5000 4000 3000 300 200 100 30 20 10 5 EQUATION Tc _ (11.9L3)0.38S ~E Tc L ~E = Time of concentration (hour...) .. Watercour$e Distince (mll11s) = Change in elevation along effective slope line (See Figure 3-5)(feet} L Miles Feet ' 3000 0.5 ' ' 2000 ' ' 1800 ' 1600 ' 1400 1200 300 200 L SOURCE: California Division of Highways (1941) and Kirplch (1940) Nomograph tor Determination of 60 50 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 Q) a. 0 in -; ~ ci5 .... 0 ~ 0 20 18 16 14 12 10 9 8 7 6 5 4 3 2 1.8 1.6 1.4 1.2 1.0 0.9 0.8 0.7 0.6 1~1.5'--+I l+-fl~.01~1 -2% ~ n =.0175 -----=-::.:..... ___ --! 2% Concrete Gutter I .I. I I I/ Paved f....... v,.. ' "-._"'10 RESIDENTIAL STREET ONE SIDE ONLY I 7---v,.. I ~<r '/ r---.. .._ , f.p ~ I ~ , I r--I f'.... I ' t----. I I j r---~ I ~ I "'8t:/') 1--) , . ·S ) ............ ~ I I ----_, ) ....,..._ I ~ I -........ I I ~ I 4..Qj ~L I .... ..__ I ...... r/-.._ • ,...__v"'6 -,-fi --<lJ I --....;,.!_p,S I ....... J? "-QJ} ---r-.::.:..._ j "' -~, l{J ~~"'sf ~ --.. I I ~1 j :S t---11 I ....... '~}__~ ~ I l.i.. r-.._(::,"? I',._ I ~ V,_ I I 1 'fij --...... <f t----._ ... </,. .,._, I'---~.~ ... -, ~ --I I ....... . l.i.. qj/ ~ t----. '7- <::)' ---, r-.... , JS1 -... 4..QJ, ,............ I ....... f.. I/_ Qll)" .........__<.::,"'?/ ... , 'r-...f r--.._ 1/ J ,..::3,/) I .sl/.............._ i'I I/ . ·S J? I .......____ r-.... / K , 01 ~~, ... , & I F'v"'.? I r---.. I 1/ ' f'-.$1 r--.... J? r-----..:._.:.s, Q r--I I ~-s. r---....1 , :s, '-.. I L .. j I J I .......____ I ✓ I..........._ , Q~ ......... 1--. I ......_ , I ........_ I ~ , --v"'<r '--If I ......... If I ~ ) ·P.s. ' r-... ---✓ I ........._ 0.5 -~ ~/ I' 0.4 I I'---I I" ...... I ...... f r--......._ "-.._._ s. • ,...__ 2 3 4 5 6 7 8 9 10 20 30 40 50 Discharge (C.F.S.) EXAMPLE: Given: Q = 10 S., 2.5% Chart gives: 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 ~ 11) I 0 .Q .... Q) a. Q) ~ .!: w a.. 0 ...J (/) 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 0.007 EQUATION: V = 1.49 R213 s112 n <.) :::i 0.2 0.3 0.4 0.5 0.6 ~ 0.8 "' 0.9 ~❖ 1.0 ~6' "' "' / ~~ 0.006 ~ / 0.005 O 3,....,...- >- >17 0-~~~ :r: ~ 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 / ; .... Q) a. Y~ Q) ~ ~ .£ ~ ""g .J w > GENERAL SOLUTION SOURCE: USDOT, FHWA, HDS-3 (1961) Manning's Equation Nomograph ro ~ r40 t 30 20 / 9 8 7 6 5 4 3 2 1.0 0.9 0.8 o:r 0.6 0.5 0.01 ()91.-/ 0.02 9' C 0.03 ' c -~ 0 ~ Q) 0.04 0 <.) (/) Cl) 0.05 w z ::c (!) 0.06 :::, 0 a::: O.Q7 0.08 0.09 0.10 0.2 0.3 0.4 FIGURE ~ ' -io.o 9.0 8.0 7,0 I' "' 6.0 5.0 , ... 4.0 ' r-- 3.0 2.0 I r,,.. I' - I' I' I' ' " ... " ' ... r.... "'"" i'r-.. ... r,,. . ' .... ' ' ... r--. '" ... I"', ' ... I' I"' ... , I".., " I"' " " " I' ' r- ' " ... r,,. ' ' r-.. ' -. I I' I' , ...... t-, 'r-, ..... ~I"~~~ "'"' i.." r-I ' ~ .. "'"'~ ' .. ... ~ r- r, ... 'r-, ~i" ~ "' .. " r-~ ~ ~ I'~ ro" ~~ ~ I ..... r-•,.,. I .. ·~ I', , .... "'" ~ I j ·~ ~ I . .E 1.0 -;::o. ~o. i ,:so. ) g 8 7 o. 0 . ,6 . 5 0 • . 4 0 . . 3 0 .2 0 1. ,--- j I 5 6 7 8 9 10 '"~ .. ' "' -.. - 15 ~~r i""'~ I ~ .~~ I -.. -. 111111111111 20 30 Minutes 40 SQ Duration I EQUATION I = 7.44 P5 o-0.64S I = lntensity (in/hr) P5 = 6-Hour Precipitation {in) D = Duraiion (min} I ' , ... .... ... ' r,,. ' I'. .... " • "'r--I" ... "' ' ... .. . ~ r,,. I'>"' j l' ,, "' ~ ~ 1-.. r,,. "'i-. "~ ~ .... I' .. ,~ ' .. " i-.._ ,.., I, ~ I """ "'~ '"'" I" I" I ' 1.,., 'I' .. r--, - --- llllllllllllill 2 3 4 Hours : ! I ! I I I I ll'!>Llll I ' '. .. ' - Ii 1 11 Ill lfll s ii 'r' g '"\ l' (I) 52. 6.0 '2. 5.5 ~ 5.0 g· 4.5 '§' . n 4.0 i5 3.5./!!. 3.0 2.5 2.0 1.5 1.0 fntensity-Ouratlon Design Chart -Template Directions for AppllcatJom (1) From precipitation maps.determine 6 ht and 24 hr amounts for the selected frequency. These maps are induded 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 that it is within the range of 45% to 65% of the 24 hr precipitation {not applicapfe to Desert). (3) Plot 6 hr precipitation on the right side of the chart. (4) Draw a llne through 1he point parallel to lhe plotted lines .. (5) This line is the intensity.<Juration curve for the location being analyzed. Application Form: (a) Selected frequency __ year . Pa. (b) Pa= in P24 = ~ = -· ·-., -'P24 (c) Adjusted P6(2l = ___ in. %(2) (d) tx = __ min. (e}I =· __ in./hr. Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. j I ! I • i • ..l Pii"---·-·t .. -, .... (1;.5 2 2.s 't .. 3 3.s 4 'i'"4~'!i'T .... s .... Ls:-s' ,···s-- ouiation·;-· .. 1 .... 7-f-·1···i-f 1-(·1-l-r --, T Y ... t -1-+ l" .. !--c · ------· s 2.e;tJM?. .211 6.59 , 7,90 .~,?? _1_0:?.'!. D.,~fl.U ~!!1.1.i:.~~lJ_s"~.1 .. .. ____ 1~ J:~~-l~;~~-~~-~~ I:: ·~:~ · !:~ ~:~ i 1~:.~f~~H~:~1 . _____ 15. 1.30.p .9512.59 3.241,3.89j 4.54 5,19 5.84 6.49 ~ 7,13 I 7.78 ,. ........... .20 1.08.+1.62L2.15J.2.69 13.23i3.n J,4.31 4.~J s.~1J5.93 i 6.46 '..~:::::~: ~:~ l~~~r:::H:~~f-i: ~::tt~~ -~:~ l ::~~.t!~·t·1::: !.:~~~--~: :g:~~~t~:~1:~J~:!~f~:~;~~1~:;:Ji~"l~::-~-f:3:~· •·--·--::. -~:~t~!~~o::1.~:~J~.::11::r1·~:~ l-~::.1--~: .. : t:.ti:~:---. -----1-•-----~---U ~h--·· ---·-----+· ····--+-·---·+-• ... ·-~--..... , I··---· t~ :0.34.JO.St 0 .. 68 .. 0.8Sj_1.881 t .191.1.36 1·1'.534).70 .. 1 l.87.~ 2.04. ____ _1_0 .. 0.29J 0.44 0.59 0.73!:0, 11,03[_1.18 ... 1.32:J.1:47 .. 11,52j 1.76. .. ,. __ 1eo o.26 'Q,~9J.9..&? .9.,~§-i,9:,~p?-~1. 1.04 us I q!0t .. 1,.Y .. p .,.?I ---240 0.22 .,.0.33~0.43 0.54J.0.65. 0.7610.87 ·•· 0.9S >~ .1.19.i. 1.30 .... -~%> 0.19 •0.2810.38 0.47 , 4?~~40.66; 0.75 j OJ~5 ; O.::,\J:~ . .!..]:~.~ 360 0.17 .0.2510.33 0.42 ,0.50;0.58 0.67· 0.76 ; 0,84 , 0.92 1 LOO 3-1 E 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 perfonn 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 boundaz;y, 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 (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 do~rnstream, assign a number representing each subarea in the drainage system to each point of interest. Figure 3-8 provides guidelines for node numbers for geographfo 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 •. ,,-··1 I . ~ '7 l.. I / ', / L-· Study Area LA 0 Define Study Areas (Two-Letter ID) 0 Define Maps (or Subregions on Region Basis) © Define Model Subareas on Map Basis , .. -4' ' ,• ~ .... . ,' .. ... .. ,---1 ........ ... . ' . . . 0 Define Major Flowpaths in Study Area 0 Define Regions on Study Area Basis Subarea ID= (LA010112) Region# N;:::------, 1 Study Area (ID) # l l I © 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 1· I~-~R 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. I 0. Calculate the 1:(CA) value(s) for the subareas upstream of the point(s) of interest. 11. Detem1ine 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 = :E(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 T1 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 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 .tv1RM 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 l 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. A~er 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 ori 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 Qi, Ti, and I, correspond to the tributary area with the sh01test Tc. Likewise, let Q2, T2, and h correspond to the tributary area with the next longer Tc; Q3, T3, and 13 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 > Qr3), use the shorter of the Tc's associated with that Q. This equation may be expanded for a j unction 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., Q1), 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 h = 0. When T 1 and T2 are the same, 11 and Ii are also the same, and T1/T2 and Ii/11 = 1. T1/T2 and h/11 are cancelled from the equations. At this point, Qr1 = Qn = Qi + 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 = 1:(CA)l. Note #3: . An optional method of determining the Tc is to use the equation Tc= [(I (CA)7.44 P6)/Q] 1.ss This equation is from Q = 2'.(CA)I = 2'.(CA)(7.44 PJTc·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