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Home My WebLink AboutCT 14-03; BEACHWALK AT MADISON; PRELIMINARY HYDROLOGY STUDY; 2014-04-16PRELIMINARY HYDROLOGY STUDY for MADISON ST CARLSBAD, CA 92009 City of Carlsbad, CA PREPARED FOR: Project Deaf India Foundation 3 Dunn St. Laguna Niguel, CA 92677 Date: April 16, 2014 PREPARED BY: Pasco Laret Suiter & Associates 535 N. Highway 101, Suite A Solana Beach, CA 9207 5 (858) 259-8212 BRIAN ARDOLINO, RCE 71651 DATE Preliminary Hydrology Study for Beachwalk at Madison PLSA2179 TABLE OF CONTENTS Executive Summary Introduction Existing Conditions Proposed Project Summary of Results and Conditions Conclusions References M~thodology Introduction County of San Diego Criteria Runoff coefficient determination Hydrologic Analyses Pre-Developed Hydrologic Aq.alysis Post-Developed Hydrologic Analysis Hydraulic Calculations Appendix 2 SECTION PAGE 1.0 3 1.1 3 1.2 3 1.3 3 1.4 4 1.5 4 1.6 5 2.0 6 2.1 6 2.2 6 2.3 7 3.0 8 3.1 9 3.2 14 4.0 19 5.0 4/16/2014 Preliminary Hydrology Study for Beachwalk at Madison PLSA2179 1.0 EXECUTIVE SUMMARY 1.1 Introduction rnrr This Hydrology Study for the Madison Street project has been prepared to analyze the hydrologic and hydraulic characteristics of the existing and proposed project site. This report intends to present both the methodology and the calculations used for determining the runoff from the project site in both the pre-developed (existing) conditions and the post- developed (proposed) conditions produced by the 100 year 6 hour storm. In addition this report will propose the sizing of all necessary storm drain facilities and storm drain piping necessary for the storm drain system to safely convey the runoff from the 100-year rainfall event. 1.2 Existing Conditions The property is geographically located at N 33°09'51.7" W 117°20'57.5". The site is bordered by a residential development to the north, south and east. Madison Street is located to the west of the proposed development. The project site is located in the Buena Vista Creek Hydrologic Area and more specifically, the El Salto Sub-Area (904.21). The existing project site is undeveloped. The site consists mostly of a gentle slope from east to west. Drainage from the existing site sheet flows in the southwesterly direction across the project site to Madison Street. The runoff is then conveyed north along Madison Street and ultimately discharges into the Buena Vista Lagoon. 1.3 Proposed Project The intent of the proposed project is to construct 6 detached townhome complexes with associated hardscape improvements, as well as frontage improvements along Madison ·Street. The project proposed grading to uniform pads for each townhome. The improvements proposed along Madison Street include the addition of curb and gutter, driveway and sidewalk improvements. The proposed drainage design includes the construction of curb and gutter along the street frontages, and Bioretention BMP areas for priority storm water treatment. The proposed pads will utilize grading to drain the pads east to west and ultimately onto Madison St as it does in the existing condition. We believe the proposed storm drain system will not adversely affect the downstream system negatively. To address the storm water quality goals established for this development, proposed permanent Best Management Practice (BMP) and treatm~nt methods will be incorporated into the storm water runoff design. The proposed BMP's include multiple Bioretention areas, which are intended to mitigate peak flows as well as serve as settling basins and are also designed to meet hydromodification criteria. 1.4 Summary of Results 4i16/2014 3 Preliminary Hydrology Study for Beachwalk at Madison PLSA2179 Upon performing hydrologic analysis of the project site in both the proposed developed and existing condition the following results were produced. One discharge point was analyzed. In the "predeveloped condition indicates that the 100-year peak flow is 0.57 cfs with a time of concentration of 9.47 min based on an area of 0.3 AC. In the postdeveloped condition indicates that the 100-year peak flow is 0.85 cfs with a time of concentration of 12.92 min based on an area of 0.3 AC. 1.5 Conclusions Based on the discussion in this report it is the professional opinion of Pasco Laret Suiter & Associates, Inc. that the existing drainage system on the corresponding Tentative Map will function to adequately intercept, contain and convey flow to the appropriate points of discharge. 4/16/2014 4 Preliminary Hydrology Study for Beachwalk at Madison PLSA2179 1.6 References ''San Diego County Ifydrology Manual': revised June 2003, County of San Diego, Department of Public Works, Flood Control Section. ''California &gional Water Quality Control Board Order No. 2009-0009-DWQ, "California Regional Water Control Board, San Diego Region (~DRWQCB). 5 4/16/2014 Preliminary Hydrology Study for Beachwalk c1t Madison PLSA2179 2.0 METHODOLOGY 2.1 Introduction 0 The hydrologic model used to perform the hydrologic analysis presented in this report utilizes the Ration Method (RM) equation, Q=CIA. The RM formula estimates the peak rate of runoff based on the variables of area, runoff coefficient, and rainfall intensity. The rainfall intensity (I) is equal to: Where: I= 7.44 x P6 x n-0·645 I = Intensity (in/hr) P6 = 6-hour precipitation (inches) D = duration (minutes -use Tc) Using the Time of Concentration (fc), which is the time required for a given element of water that originates at the most remote point of the basin being analyzed to reach the point at which the runoff from the basin is being analyzed. The RM equation determines the storm water runoff rate (Q) for a given basin in terms of flow (typically in cubic feet per second (cfs) but sometimes as gallons per minute (gpm)). The RM equation is as follows: Where: Q=CIA Q= flow (in cfs) C = runoff coefficient, ratio of rainfall that produces storm water runoff (runoff vs. infiltration/ evaporation/ absorption/ etc) I = average rainfall intensity for a duration equal to the Tc for the area, in inches per hour. A = drainage area contributing to the basin in acres. The RM equation assumes that the storm event being analyzed delivers precipitation to the entire basin uniformly, and therefore the peak discharge rate will occur when a raindrop falls at the most remote portion of the basin arrives at the point of analysis. The RM also assumes that the fraction of rainfall that becomes runoff or the runoff coefficient C is not affected by the storm intensity, I, or the precipitation zone number. In addition to the above Ration Method assumptions, the conservative assumption that all runoff coefficients utilized for this report are based on type "D" soils. 2.2 County of San Diego Criteria As defined by the County Hydrology Manual dated June 2003, the rational method is the preferred equation for determining the hydrologic characteristics of basins up to approximately one square mile in size. The County of San Diego has developed its own tables, nomographs, and methodologies for analyzing storm water runoff for areas within the county. The County has also developed precipitation isopluvial contour maps that show even lines of rainfall anticipated from a given storm event (i.e. 100-year, 6-hour storm). 4/16/2014 6 Preliminary Hydrology Study for Beachwalk at Madison PLSA 2179 One of the variables of the RM equation is the runoff coefficient, C. The runoff coefficient is dependent only upon land use and soil type and the County of San Diego has developed a table of Runoff Coefficients for Urban Areas to be applied to basin located within the County of San Diego. The table categorizes the land . use, the associated development density (dwelling units per acre) and the percentage of impervious area. Each of the categories listed has an associated runoff coefficient, C, for each soil type class. The County has also illustrated in detail the methodology for determining the time of concentration, in particular the initial time of concentration. The County has adopted the Federal Aviation Agency's (FAA) overland time of flow equation. This equation essentially limits the flow path length for the initial time of coacentration to lengths of 100 feet or less, and is dependent on land use and slope. 2.3 Runoff Coefficient Determination As stated in section 2.2, the runoff coefficient is dependent only upon land use and soil type and the County of San Diego has developed a table of Runoff Coefficients for Urban Areas to be applied to basin located within the County of San Diego. The table, included at the end of this section, categorizes the land use, the associated development density ( dwelling units per acre) and the percentage of impervious area. 4/16/2014 7 Preliminary Hydrology Study for Beachwalk at Madison PLSA2179 3.0 HYDROLOGIC ANALYSES 4/16/2014 8 **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-2008 Advanced Engineering Software (aes) Ver. 15.0 Release Date: 04/01/2008 License ID 1452 Analysis prepared by: PASCO LARET SUITER AND ASSOCIATES 535 N. HWY. 101 SUITE A SOLANA BEACH, CA 92075 PHONE (858) 259-8212 FAX (858) 259-4812 FILE NAME: 2179E.DAT TIME/DATE OF STUDY: 11:51 04/16/2014 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) = 4.00 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 0.0313 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 2.20 TO NODE 2.10 IS CODE= 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT= .3500 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 70.00 · UPSTREAM ELEVATION(FEET) = 53.70 DOWNSTREAM ELEVATION(FEET) = 51.40 ELEVATION DIFFERENCE(FEET) = 2.30 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 100 YEAR RAINFALL INTENSITY(INCH/HOUR) SUBAREA RUNOFF(CFS) 0.09 7.598 5.230 TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) 0.09 **************************************************************************** FLOW PROCESS FROM NODE 2.20 TO NODE 2.10 IS CODE= 7 >>>>>USER SPECIFIED HYDROLOGY INFORMATION AT NODE<<<<< USER-SPECIF·IED VALUES ARE AS FOLLOWS': TC{MIN) = 7.60 RAIN INTENSITY(INCH/HOUR) = 5.23 TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) = 0.10 **************************************************************************** FLOW PROCESS FROM NODE 2.10 TO NODE >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA<<<<< 2.00 IS CODE= 52 ELEVATION DATA: UPSTREAM(FEET) = 51.40 DOWNSTREAM(FEET) = CHANNEL LENGTH THRU SUBAREA(FEET) = 58.00 CHANNEL SLOPE= NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.10 FLOW VELOCITY(FEET/SEC) = 2.85 (PER LACFCD/RCFC&WCD HYDROLOGY TRAVEL TIME(MIN.) = 0~34 Tc(MIN.) = 7.94 49.30 0.0362 MANUAL) LONGEST FLOWPATH FROM NODE 2.20 TO NODE 2.00 = 128.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 2.00 TO NODE 1.00 IS CODE= 61 >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>(STANDARD CURB SECTION USED)<<<<< ======================================~===================================== UPSTREAM ELEVATION(FEET) STREET LENGTH(FEET) = STREET HALFWIDTH(FEET) 49.30 DOWNSTREAM ELEVATION(FEET) 97.00 CURB HEIGHT(INCHES) = 6.0 14.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) 9.00 INSIDE STREET CROSSFALL(DECIMAL) 0.020 OUTSIDE STREET CROSSFALL(DECIMAL) 0.020 SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF 1 STREET PARKWAY CROSSFALL(DECIMAL) 0.020 47.70 Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) 0.0300 Manning's FRICTION FACTOR for Back-of-Walk Flow Section 0.0200 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) STREETFLOW MODEL RESULTS USING ESTIMATED FLOW: STREET FLOW DEPTH(FEET) = 0.22 HALFSTREET FLOOD WIDTH(FEET) = AVERAGE FLOW VELOCITY(FEET/SEC.) 4.54 1. 05 0.34 PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) 0.23 STREET FLOW TRAVEL TIME(MIN.) = 1.53 Tc(MIN.) 9.47 100 YEAR RAINFALL INTENSITY(INCH/HOUR) 4.537 *USER SPECIFIED(SUBAREA): RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT .4400 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT 0.430 SUBAREA AREA(ACRES) 0.24 SUBAREA RUNOFF(CFS) 0.48 TOTAL AREA(ACRES) = 0.3 PEAK FLOW RATE(CFS) 0.57 END OF SUBAREA STREET FLOW HYDRAULICS: DEPTH(FEET) = 0.25 HALFSTREET FLOOD WIDTH(FEET) 6.16 FLOW VELOCITY(FEET/SEC.) = 1.15 DEPTH*VELOCITY(FT*FT/SEC.) 0.29 LONGEST FLOWPATH FROM NODE 2.20 TO NODE 1.00 = 225.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) PEAK FLOW RATE(CFS) 0 • 3 TC ( MIN . ) = 0.57 END OF RATIONAL METHOD ANALYSIS 9.47 **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-2008 Advanced Engineering Software (aes) Ver. 15.0 Release Date: 04/01/2008 License ID 1452 Analysis prepared by: PASCO LARET SUITER AND ASSOCIATES 535 N. HWY. 101 SUITE A SOLANA BEACH, CA 92075 PHONE (858) 259-8212 FAX (858) 259-4812 FILE NAME: 2179P.DAT TIME/DATE OF STUDY: 11:56 04/16/2014 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) = 4.00 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 0.0313 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 4.00 TO NODE 3.20 IS CODE= 21 >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< -.----------------------------------~--------------------------------------- *USER SPECIFIED(SUBAREA): RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT= .5500 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 70.00 UPSTREAM ELEVATION(FEET) = 49.30 mlllli!ll!lll!!lllllll'!ll~W=:b.~wm:ma:z~a!i~·lllijll[IIIII ........................................................................ . DOWNSTREAM ELEVATION(FEET) = 48.90 ELEVATION DIFFERENCE(FEET) = 0.40 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 8.673 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH= 52.86 (Reference: Table 3-lB of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.802 SUBAREA RUNOFF(CFS) 0.06 TOTAL AREA(ACRES) = 0.02 TOTAL RUNOFF(CFS) 0.06 **************************************************************************** FLOW PROCESS FROM NODE 4.00 TO NODE 3.20 IS CODE= 7 >>>>>USER SPECIFIED HYDROLOGY INFORMATION AT NODE<<<<< USER-SPECIFIED VALUES ARE AS FOLLOWS: TC(MIN) = 8.60 RAIN INTENSITY(INCH/HOUR) = 4.83 TOTAL AREA(ACRES) = 0.02 TOTAL RUNOFF(CFS) = 0.10 **************************************************************************** FLOW PROCESS FROM NODE 3.20 TO NODE >>>>>COMPUTE NATURAL VALLEY CHANNEL FLOW<<<<< >>>>>TRAVELTIME THRU SUBAREA<<<<< 3.10 IS CODE= 52 ELEVATION DATA: UPSTREAM(FEET) = 48.90 DOWNSTREAM(FEET) = CHANNEL LENGTH THRU SUBAREA(FEET) = 80.00 CHANNEL SLOPE= NOTE: CHANNEL FLOW OF 1. CFS WAS ASSUMED IN VELOCITY ESTIMATION CHANNEL FLOW THRU SUBAREA(CFS) = 0.10 FLOW VELOCITY(FEET/SEC) = 1.50 (PER LACFCD/RCFC&WCD HYDROLOGY TRAVEL TIME(MIN.) = 0.89 Tc(MIN.) = 9.49 48.10 0.0100 MANUAL) LONGEST FLOWPATH FROM NODE 4.00 TO NODE 3.10 = 150.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 3.10 TO NODE 3.00 IS CODE= 31 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ===--===--===--==---=----=-------------------------------------------------- ELEVATION DATA: UPSTREAM(FEET) = 48.00 DOWNSTREAM(FEET) 47.90 FLOW LENGTH(FEET) = 11.00 MANNING'S N = 0.013 DEPTH OF FLOW IN 6.0 INCH PIPE IS 1.8 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) 1.98 ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES 1 PIPE-FLOW(CFS) = 0.10 PIPE TRAVEL TIME(MIN.) = 0.09 Tc(MIN.) = 9.58 LONGEST FLOWPATH FROM NODE 4.00 TO NODE 3.00 161.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 3.00 TO NODE 1.00 IS CODE= 61 >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>(STANDARD CURB SECTION USED)<<<<< UPSTREAM ELEVATION(FEET) STREET LENGTH(FEET) = STREET HALFWIDTH(FEET) 47.90 DOWNSTREAM ELEVATION(FEET) 98.00 CURB HEIGHT(INCHES) = 6.0 14.00 DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) 9.00 INSIDE STREET CROSSFALL(DECIMAL) 0.020 OUTSIDE STREET CROSSFALL(DECIMAL) 0.020 SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF 1 STREET PARKWAY CROSSFALL(DECIMAL) 0.020 47.70 Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) 0.0300 .Manning's .FRICTION FACTOR for Back-of-Walk Flow Section 0.0200 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) 0.49 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW: STREET FLOW DEPTH(FEET) = 0.31 HALFSTREET FLOOD WIDTH(FEET) = 9.39 AVERAGE FLOW VELOCITY(FEET/SEC.) 0.49 PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) 0.15 STREET FLOW TRAVEL TIME(MIN.) = 3.34 Tc(MIN.) 12.92 100 YEAR RAINFALL INTENSITY(INCH/HOUR) 3.714 *USER SPECIFIED(SUBAREA): RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT .7400 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT 0.750 SUBAREA AREA(ACRES) 0.28 SUBAREA RUNOFF(CFS) = 0.77 TOTAL AREA(ACRES) = -0.3 PEAK FLOW RATE(CFS) 0.85 END OF SUBAREA STREET FLOW HYDRAULICS: DEPTH(FEET) = 0.36 HALFSTREET FLOOD WIDTH(FEET) 11.86 FLOW VELOCITY(FEET/SEC.) = 0.56 DEPTH*VELOCITY(FT*FT/SEC.) 0.20 LONGEST FLOWPATH FROM NODE 4.00 TO NODE 1.00 = 259.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) . PEAK FLOW RATE(CFS) 0.3 TC(MIN.) = 0.85 END OF RATIONAL METHOD ANALYSIS 12.92 Preliminary Hydrology Study for Beachwalk at Madison PLSA2179 4.0 HYDRAULIC CALCULATIONS 4/16/2014 9 Preliminary Hydrology Study for Beachwalk at Madison PLSA2179 5.0 APPENDIX 4/16/2014 10 l'.fflt¥til#ft ' !d -c WT? =; f"'tr·wnm:--ww-~·'"·w iii r=~~~ "·~"~Yt'" '·"·'"~""W tt::ee·=r:·-·e:-r f .,.. r ; ti .. J. • .;: ........ _ ... ~-~-~-l----1~--'-~-l-; .... c_, .. ~., ....... +········c-·····•····· ·····1···············-··•····!···~+-·->--··--133•30' .32"45'. ' -· . 32·~ ··--· ·-~ ; ·~ it) :: l!l ~···· ., ; .... ~ "!? - 32°30' County of San Diego Hydrology Manual • Rainfall Isopluvials 100 ¥~ Rainfall Event -6 Hours [·--·--·--~ •••••••• lsopluvlal (Inches) ························································-····-~········· 1,.~'T1rut>1a : l'la~t <t' ,,.1" LOl'ICli\Nt>t,: ..Sill" at,' 51,5" P. • a.,eo 01 [)PW •GIS ~,GIS \\t~ f {;,h.: ;U; J.)i,\;t"• C,,v, IC\!! ~flll\J:t'4.l(.l/m &<>r ........ ~ ..... $,,ot«icl .. N nl8 ~ 18PAOWIBI wmfOUTWMtWlr'(OF #NIOIC>. EmERUPRE88 + OR....-,,IICLl,IIMl,IUT. NOT~TO,THEIIIPLll!OWARIWITltS OF ..,...,..,.AIUN ANO FfflEU FOR AP'AR'l'ICl.ll.M PUN'OSE. s ~ ....... ,,,--~. ,.. .......... ~ ...................... S#«)IIO~ ...................... ......,..._ ... .... ,........,,MtrlJillG n-....,._, .... ~llhldl-.... ...,.._..,,., ..,.._..,.....,,,..,_......,..., 3 0 3 Miles ~ San Diego County Hydrology Manual Date: June 2003 ' Section: Page: Table3-1 RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use I Runoff Coefficient "C" SoilT~ NRCS Elements C Elements %IMPER. A B Undisturbed Natural Terrain (Natural) Pennanent Open Space O* 0.20 0.25 Low Density Residential (LOR) Residential, 1.0 DU/A or less 10 0.27 0.32 Low Density Residential (LDR) Residential, 2.0 DU/A or less 20 0.34 0.38 Low Density Residential (LOR) Residential, 2.9 DU/A or less 25 0.38 0.41 Medium Density Residential (MDR) Residential, 4.3 DU/A or less 30 0.41 0.45 Medium Density Residential (MDR) Residential, 7.3 DU/A or less 40 0.48 0.51 Medium Density Residential (MDR) Residential, 10.9 DU/A or less 45 0.52 0.54 Medium Density Residential (MDR) 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 less 80 0.76 0.77 Commercial/Industrial (N. Com) Neighborhood Commercial 80 0.76 0.77 Commercial/Industrial (G. Com) General Commercial 85 0.80 0.80 Commercial/Industrial (O.P. Com) Office Professional/Commercial 90 0.83 0.84 Commercial/[ndustrial (Limited I.) Limited Industrial 90 0.83 0.84 Commercial/Industrial (Gener.al 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 6of26 D I O.J5 I 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-li 0 e -.1 , ~~, . .,,,r ·,-;, .. ')'.,\4ifl%s"'¥9::-.'ifirt:r:frrtrffi1M325#tif1N'M"'t"is···---. a ... tr itrt''M"W!Ffrt · · ,~"] ····--·r Wr"" :r·~JKuttr ,-u·-· ~-~"'""·~·--·-·· 6 7 8 9 10 15 20 30 40 501 Minutes Duralibn EQUATION = 7.44 Ps o-0,645 = lntem,ity (Whr) 6-Hour Precipilation (in) Duration (min) I ll111m1 m ± II ~ ! 6.0~ 5.5 ~ 5.0 :, 4.5~ g. 4.0 Ii 3.5 - 3.0 2.5 2.0 1.5 1.0 2 3 4 5 8 Hour& Intensity-Duration Design Chart -Template Directions for~: (1} F,om preciplalic)n maps detennine 6 hr and 24 hr amounts for the Hlededfrequency. These maps n lnduded In the Ceunty Hydn:ilDgy Manual {10, 50. and 100 yr maps included in the Design arid Protedure Manual). (2) AdJust 6 hr praeipitation· (if nec:iessary) so that it ls within the rlilt'lgi& of 45"!'10 65% of the 24 hr pteCiplbltlon (not applicaple to Desert). (3) Plot 6 hr pteapil8tion on the right side of the et,art. (4) Draw allne through lhJ! pointPM@!!tJ.~~ plotted lines. (5) This Bne is the intensity-duration curve for the location being analyzed. Application Form: (a) Selected frequency __ year . Pi: (b) P5 = --in •• P24 = --•Jr = 24 (c) Adjusted P612) = __ in. (d) fx: __ min. (e) I= __ lnJhr. %12) Note: This chart replaces the tntensity-Duration-Frequency curves used since 1965. u 2·u 3 u· • u· s s.s & . I . I I I I I . I I I I 2.63 315;5.27 6.Slf 7.90~Q.5411.li6'13.17-1,f4$ 15.81 2.12 ':i.ti' 4.24'. $3) 6.36 7..tfll.48 iti54 10.60 1t.sa· 12.12 .lfi).~?J~!i::!: Ji~t!~ :ii: f!: i!i?~~iii o.e:s. ,.~:,.a1. u.(2.io1~2(~:n: ~.i> :·4,ir; s.13: s;eo U3 1.24 use 201 2 ... , uo 3.32. 3,73 4.ts; ,us 4.98 if.I)~ \«i:1.:J.s:, 12 2.0(241;-2·.n; 3.10 · a4S. 379. ,,13 ·~ . o~.1.1,. 1.49. 1.79, 2os, u, . us, ~!!O i 3.28. 3,!i8 OJi3 0,80 UIII 1.31 UI 186 2'12 2.39 . 2.65 2.92 3.18 ;1.ia :~::::i!:ii'.tl:! H: \ i~~ t:: tE J:; J!:~~v,~j)~; o.66 .1),1,8_0.,1. UM. 1 .. ,~ .• J.31, 1.44, t.57 ,.;;r~ 11J!,9.:~,5:l,~!l),:,S. U7. O:~, 1.cJ!; 1.19 d~ ~1),19 .. ,.;0,38, 0.41.0. ,o.fi8, 0.75. US, l).9t. \.~, 1.13 0. 11 US o.33 O.~ Q.4i0 0.58 O.IJZ 0,75 l>.84 , Cl.92 . 1,® IPl~TI e 0 " 0 San Diego County Hydrology Manual Date: June 2003 0 Section: Page: 3 12of26 Not~ that the Initial Time of Concentration should be reflective of the general land-use at the upstream end of a drainage basin. A single lot with an area of two or less acres does not have a significant effect where the drainage basin area is 20 to 600 acres. Table 3-2 provides limits of the length (Maximum Length (LM)) of sheet flow to be used in hydrology studies. Initial Ti values based on average C values for the Land Use Element are also included. These values can be used in planning and design applications as described below. Exceptions may be approved by the "Regulating Agency" when submitted with a detailed study. Table3-2 MAXIMUM OVERLAND FLOW LENGTH (LM) & INITIAL TIME OF CONCENTRATION (Ti) Element• DU/ .5% 1% 2% 3% 5% 10% Acre LM Ti LM Ti LM Ti LM Ti LM Ti LM Ti Natural 50 13.2 70 12.5 85 10.9 100 10.3 100 8.7 100 6.9 LOR 1 50 12.2 70 11.5 85 10.0 100 9.5 100 8.0 100 6.4 LOR 2 50 11.3 70 10.5 85 9.2 100 8.8 100 7.4 100 5.8 LOR 2.9 50 10.7 70 10.0 85 8.8 95 8.1 100 7.0 100 5.6 MOR 4.3 50 10.2 70 9.6 80 8.1 95 7.8 100 6.7 100 5.3 ' MOR 7.3 50 9.2 65 8.4 80 7.4 95 7.0 100 6.0 100 4.8 MOR 10.9 50 8.7 65 7.9 80 6.9 90 6.4 100 5.7 100 4.5 MOR 14.5 50 8.2 65 7.4 80 6.5 90 6.0 100 5.4 100 4.3 HOR 24 50 6.7 65 6.1 75 5.1 90 4.9 95 4.3 100 3.5 HOR 43 50 5.3 65 4.7 75 4.0 85 3.8 95 3.4 100 2.7 N.Com 50 5.3 60 4.5 75 4.0 85 3.8 95 3.4 100 2.7 G.Com 50 4.7 60 4.1 75 3.6 85 3.4 90 2.9 100 2.4 O.P./Com 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2 Limited I. 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2 General I. 50 3.7 60 3.2 70 2.7 80 2.6 90 2.3 100 1.9 • See Table 3-1 for more detailed description 3-12 "p'.[-MMi'i&--:!a."s,:(.··oo:.·· 'crerrw 751 nt z:rvtrrwearsm M7Wi7t'ltilt2 me-~stt,.. i:-;"H. I ; HYDROLOGIC NODE MAP BEACHWALK AT MADISON PREOEVELOPMENT MAP -·---! '"M/'!i.t;l-1:"~)d.f t-\ f7i.1:J:-:f::· .. .1.~······-~, ~.·x' .. ~.):.... . .... ~ .. !.1/I>·{~:.~~ ... / ........... ;_x~~ .......... x ~-~ L _ A-8,702 SF• 0.199 AC . C-0.35 A•.1,390 SF• O.D3f9., AC C-0.35 ' .-~r~t)s:·,;~; \A-eal(} SF • 0.0523 AC \ C-0.35 . ---.,, -,.___ -~· .. ---'• I=-1ASCO LAREY SUITER1 !1,-llli--11111111 & ASSOCIATES! _ ............... I.MID._... jUI ...... ......, 111,, ... A. ........... CA,_,. ~~~12 .oITT":. I i ~ HYDROLOGIC NODE MAP BEACHWALK AT MADISON ;•••••••-·M,•• ' ~f.!.,Oj; ' ', POST OEVELOPMENT MAP . ~"' _:,;:'=':,'~~~, _L - I -; ,. 11 ~ fl Ii I 1fa 111 I I, I ~· "~j \, ..... ~JI ~~~~'~--~ ,'!',(,, 1!.P.%,l/l.l ,u~; PASCO LARET SUITER I•----& ASSOCIATES CML._...+UIID,._,.+LMID_,_ SHN ... S...., 111. ... ,.. ............ CA nus ISUH.1112lh:UUSIIM12