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HomeMy WebLinkAboutCUP 2017-0008; PRELIMINARY HYDROLOGY STUDY; 2018-01-01I RECORD COPY po— q//7 /I q Initia l hate PRELIMINARY HVR[GY City of Carlsbad Oakmont of Carlsbad Lot I of Tract No. 14926 CUP 2017-0008 Prepared For: Oakmont Senior Living 9240 Old Redwood Highway, Suite 200 Windsor, CA 95492 Prepared By: Alliance Land Planning & Engineering, Inc. 2248 Faraday Ave. Carlsbad, CA 92008 /0— FFB 2 1. 2018 JANUARY 2018 REV: 2 61 'c c 13ia LMjV . . Table of Contents INTRODUCTION.................................................................. ...................................................... 2 Purpose of Study Scope - Existing and Proposed Drainage STUDYAREA............................................................................................................................2 Soils Groups Land Uses HYDROLOGY.............................................................. . ............................................................. 3 Modified Rational Method Description Program Process RESULTS................................................................................................................................... 4 CONCLUSION....................................................... . ................................................................... 4 List of Appendices APPENDIX A - Vicinity Map APPENDIX B - Site Development Plan APPENDIX C - Rational Method Reference Charts APPENDIX D - Isopluvial Map (100-Year, 6-Hour & 100-Year, 24-Hour) APPENDIX E - Hydrologic Soils Group Map APPENDIX F - Hydrologic Modeling Output (CivilDesign) - Developed Condition 100-Year APPENDIX G - Existing Condition Reference Plans APPENDIX H - Developed Condition Hydrology Map 1 INTRODUCTION Purpose of Study The Oakmont assisted living facility project is located on the north side of Faraday Avenue, west of the intersection at El Fuerte Street in the City of Carlsbad, San Diego County (see Appendix A for Vicinity Map). In the current state, the project is a mass graded lot (Lot 1) per Grading plans 415-9A, Appendix G. Lot 1 is approximately 6.38 acres. This study will consider the proposed disturbed site area consisting of 5.64 acres. The purpose of this hydrology study is to assess peak flowrates for the proposed Oakmont facility (see Appendix B). The developed site will consist of a three-story luxury assisted living facility, a two-story memory care building, and a one-story models building. A pool, parking areas, pickle ball court, bocci ball court, outdoor picnic area, various landscaped areas, and associated infrastructure are also proposed. Scope - Existing and Proposed Drainage The existing mass graded pad for Oakmont of Carlsbad drains to an existing desilting basin located inside the southeastern corner of the property near the street intersection of Faraday Avenue and El Fuerte. A spillway outlets the onsite desilting basin and runs south to an existing diverter box that splits drainage from higher magnitude stormwater flows. An existing water quality basin is located just offsite to the east of the property for low flows (see Sheet 20 of Dwg No 415-9C Appendix G). High flows run to an existing 24" stormdrain that runs beneath Faraday Ave to the southeast corner of the El Fuerte and Faraday intersection where they are discharged to the natural channel and canyon below. Prior to discharge into the offsite canyon, stormwater flows from the Oakmont project site are comingled within the 24" drain with street flows from Faraday Ave and El Fuerte. All existing onsite and offsite stormdrain infrastructure, including the 24" RCP, was originally designed for an industrial land use site previously proposed on this property. The industrial site was only rough graded with drainage items installed and was never constructed. The developed condition site will not utilize the offsite water quality basin for low flows. Proposed structural BMPs will be used to treat onsite flows, and include two biofiltration basins and one media filter. All treated flows will be routed to a new manhole installed just downstream of the existing diverter box at southeast corner of the site. The diverter box will remain, however it will be plugged with brick and mortar at the existing 12" low flow outlet, and the outlet line will be abandoned. The treated flows will drain south across Faraday Avenue through the existing 24" RCP public storm drain system (see Appendix G, Sheet 20 of As-Built Stormdrain Plans for Dwg No 415-9C). It should be noted that the 100-year discharge for the proposed Oakmont project is shown not to exceed the design capacity of the existing 24" RCP shown on Sheet 20 of Dwg No 415-9C. 2 STUDY AREA Soils Groups The site is characterized by soil group D. Refer to Hydrologic Soils Group Map, Appendix E. Hydrologic group D soils have very slow percolation rates when thoroughly wet. The rate of water transmission is very slow. Land Use The proposed land use is a mix of High Density Residential use (24DU/AC or less) and open space for the landscaped portion. The composite land use and soil group have been used to determine a runoff coefficient of 0.71 for the proposed hydrology calculations. HYDROLOGY The hydrologic analyses are performed according to the 2003 San Diego County Hydrology Manual. The overall drainage area is less than one square mile and includes junctions of independent drainage systems; therefore, the Modified Rational Method is being used for the analysis. The Modified Rational Method is applicable to a 6-hour storm duration because the procedure uses Intensity-Duration Design Charts that are based on a 6-hour storm duration. In some cases, the 6-hour precipitation must be adjusted based on the ratio of the 6- to 24-hour precipitation. This will be performed where necessary. Modified Rational Method Description The modified rational method, as described in the 2003 San Diego Flood Control/Hydrology Manual, is used to estimate surface runoff flows. The basic equation: Q = CIA C = runoff coefficient (varies with surface) = intensity (varies with time of concentration) A = area in acres For the 100-year design storm, the 6-hour rainfall amount is 2.8 inches and the 24-hour rainfall amount is 5.1 inches (see Appendix D). San Diego County Rational-Hydrology Program Package Version 7.9, developed by CIVILCADD/CIVILDESIGN Engineering Software © (1991-2012), was used to determine the rainfall amount, times of concentration, corresponding intensities and flows for the various hydrologic basins within this model. The program was then used to route flows through drainage conveyance structures and confluence basins per the modified rational method. Program Process The Rational-Hydrology program is a computer-aided design program where the user develops a node link model of the watershed. Developing independent node link models of each interior watershed and linking these subareas together at confluence points create the node link model. The program has the capability of performing calculations for 11 different hydrologic and hydraulic processes. These processes are assigned and printed in the output. They are as follows: Initial sub-area input, top of stream. Street flow through sub-area, includes sub-area runoff. Addition of runoff from sub-area to stream. Street inlet and parallel street and pipeflow and area. Pipeflow travel time (program estimated pipe size). Pipeflow travel time (user-specified pipe size). Improved channel travel - Area add option. Irregular channel travel time - Area add option. User-specified entry of data at a point. Confluence at downstream point in current stream. Confluence of main streams. RESULTS The results of the analysis of the runoff from Oakmont of Carlsbad are presented below: 100-YEAR STORM EVENT Acreage Q (cfs) Existing Condition (Allowable) 5.52 28.1 Developed Condition 5.64 23.5 0.12 -4.6 CONCLUSION Site drainage patterns in the developed condition will drain southeast to an existing underground 24" storm drain line along Faraday Ave, and there will be no increase in peak flowrate on the existing storm drain infrastructure. Drainage will be routed to water quality basins and a biofiltration unit not shown in this report. Therefore, developed Qs are conservative. Detailed Qioo routing analysis through on site water quality basins will be included in final design hydrology report. The developed condition 100-year peak flowrates do not exceed the design capacity of the existing 24" RCP shown on Sheet 20 of Dwg No 415-9C. The existing underground storm drain the project outlet drains to will not directly discharge into the ultimate receiving water body, Agua Hedionda Lagoon. Therefore, this project is deemed not exempt from hydromodification, and is discussed in detail in the SWQMP Report associated with this project. This project is considered to have no significant hydrologic impacts to the surrounding environment and is acceptable for development. 4 \\ I SITE LOCATION FARADAY 5 () Vicinity Map NO SCALE . . PRELIMINARY TITLE REPORT LAND USE ASSA LA flU MLL.A% ORISt SAnE AT AM 'm-m'A_umNGS RIRTOSAn CVLILAnOAL SOLAR LPSVJG PROVIDERS QJSIWO SORTISA, UV-AAASSZA (X) LEGAL DISCRIPTION SrRT EALATAS ALALSOAL SASO SOTEA —A NGNW 1-14. MAP j; ATO ARM: m-G0 .4 SPACE3 MEMO GROSS LAND AREA 38 ACRES 167 SPn J i CITY OF CARLBAI) 1.) PARKING SPACEG PROIDED /r ( GRE SP CE SSA8SASO7R RITA - VA TART AAAUTAA A ZONING YDYAL RT: El SPACES j AAOSTAA PROJECT DATA SCHEDULE "B" EASEMENTS CGRVACTOR TYPT -81- U, - PARKING GARAGE AS A AAUT7SS VOlT An RLA AT AVG 05055 ULTVG VillA- M ruc, 0507 CART VA NN—.AD PARKIDIS CA NA. AS EASEMENT - PVINJG )WIDES AND RACE ROPOVA 0101600 NALOMRT A. AIR STR0000LAIDI, COLIOACISO 1'IPO VA 0500EACITSO 50 // CVlACI A VVS AVCTAnA 000100710 PAOAVAVAAAVAC IAO VA A— WE-N0TPt0TYAAll TOTAL - A— 1711" ED :: ; 5071 / THE FEAR: A. IS SR SPECIFIC PLAN FLOOD ZONE DESIGNATION T\ =ALAN CNAN DIF -. AREAS OF 19 ANNNAL GE IS MAY 16. BASIS OF BEARINGS LEGEND 11 A 1P1 = ICR 117 PER -MING SrRERC EGG GROSSIALK \\ EUILDING i, 51100 000.060 Wc 7VA 4 I S I SA—GE NCCA` DRAIN ENITZME I/ 0,M1CAAAlA DA0.OSURE 0/ROOT VDL UNIT SUMMARY N' 57EV' An SI / 00 sm&i 7 ETNCR. 05 5000 ___ AAZ 97 rIAnAD, — Of SAN DEGRA. STATE OF / -L - -( - ;>' 0 AZ 0 5g 04 I-1 CARLEEAD NIMN RE— 1. IN WE UJ 1500 710017100 An 110 00100 200000 ... II MR WE GA.EMT 4 I. G loss 11 0 BENCHMARK 0010 50005 010 17 ALAILL000A 0100510100055 ....- ... --'-'17-.--- pj 152 D UNIT 000100 RESOLD 5015 11An 05 — — — - —_-- OSRI. OR SRI 0P.AA 00 00 000 401016000. 40-101 0551 An .. - .0- - - ." 400000 ROASAT 001 0245 1000001 ARE 6400 00 550500 fOR GRAPHIC SCALE 550-10101. LAVA - A UNITS 0005505 1121 (PT. 00 00 00 0010)400-00 fl NEGG 175 PLANS PREPARED Ell:- ORNOOSA, -- PLANS P0071000 FOR: I PROPEOT'Y 000110 51100 CITY OF CARLSBAD 5570 AWANCE LAND PLEIOLINE000000VRITN ISO. f . SAN DIEGO 000LTI P0007 00515 000.501551 NO: OAKMONT SITE OAKMONT PLAN 25001 100006? ROAD ALLiANCE 2200 FAR *DAY 010.. CARLSBAD, CE 40005 (750) 001.VDRDS ,05 % 0100-10 0551CR 5000 0051207? SOLAR uLIAS OpT1D*U1 2' ALUMINUM DISC STAMPED 0715 CONTROL Pt 0000 OROLER 4000 DOJIMONR 50200 UA100 0000226121 DICOWLS 60. 104. 55 % x. STREET 4040 0.0 R. 0577. SAlVE 200 LQCAJJO±IL SO SDER200 00R111 ODE An PALOAAAR AIRPORT ROAD. ROS OF 0.0055 50. SORES 020 CONCOURSE BLVD. SAN DIEGO COUNTY, CALIFORNIA PLAN TART NN GEM RID 00 07 7/10/71 o ,. 000.! ASS NO OCR CA 54 011111 000000 DOUSHEOTY (707) 520-321O RECORD "DIN,> MS. 055 5021 52. CA 0115: 41110 005000 DOUGHERTY (707) 5352011 XXX FARADY AVENUE CARLSBAD, CA 92008 000 SANORTID 1410 CAIIAT• SITS WI SROITIS ________________________ WOO OAKMONT OF CARLSBAD SITE PLAN LOT 1 OF TRACT No. 14926 7/13/17 w "WN VILIOIST VISAS, San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 6 of 26 Table 3-1 RUNOFF COEFFICIENTS FOR URBAN AREAS Coefficient "C" Undisturbed Natural Terrain (Natural) Low Density Residential (LDR) Low Density Residential (LDR) Low Density Residential (LDR) Medium Density Residential (MDR) Medium Density Residential (MDR) Medium Density Residential (MDR) Medium Density Residential (MDR) High Density Residential (HDR) High Density Residential (HDR) Commercial/Industrial (N. Corn) Commercial/Industrial (0. Corn) Commercial/Industrial (O.P. Corn) Commercial/Industrial (Limited 1.) Commercial/Industrial (General l. Elements Permanent Open Space Residential, 1.0 DUIA or less Residential, 2.0 DU/A or less Residential, 2.9 DUIA or less Residential, 4.3 DU/A or less Residential, 7.3 DUIA or less Residential, 10.9 DU/A or less Residential, 14.5 DU/A or less Residential, 24.0 DU/A or less Residential, 43.0 DU/A or less Neighborhood Commercial General Commercial Office Professional/Commercial Limited Industrial General Industrial Soil Type A B C D 0* 0.20 0.25 0.30 0.35 10 0.27 0.32 036 0.41 20 0.34 0.38 0.42 0.46 25 0.38 0.41 0.45 0.49 30 0.41 0.45 0.48 0.52 40 0.48 0.51 0.54 0.57 45 0.52 0.54 0.57 0.60 50 0.55 0.58 0.60 0.63 65 0.66 0.67 0.69 0.71 80 0.76 0.77 0.78 0.79 80 0.76 0.77 0.78 0.79 85 0.80 0.80 0.81 0.82 90 0.83 0.84 0.84 0.85 90 0.83 0.84 0.84 0.85 95 0.8 0.87 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 3-6 100 30 C,) w I.- w Lu U. o 20 z z I— - I- U) -J U. Lu U) D ll 0 C) w Ui > 0 - -- EXAMPLE: Given: Watercourse Distance (D) = 70 Feet Slope (s) =1.3% T— 1.8 (1 .1-C) Y5 Runoff Coefficient (C) = 0.41 - 3 Overland Flow Time (1) = 9.5 Minutes SOURCE: Airport Drainage, Federal Aviation Administration, 1965 FIGURE Rational Formula - Overland Time of Flow Nomograph 3-3 r '=V4P loCr San Diego County Hydrology Manual Section: 13 Date: June 2003 Page: 12 of 26 Note that the Initial Time of Concentration should be reflective of the general land-use at the upstream end of a drainage basin. A single tot 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 Tj 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. Table 3-2 MAXIMUM OVERLAND FLOW LENGTH (L 1) & INITIAL TIME OF CONCINTRATION (T Element* DU/ Acre .5% 1% 2% 3% 5% 10% LM Tj LM Tj, LM Ti LM T1 LM Tj LM IT Natural 50 13.2 70 12.5 85 10.9 100 10.3 100 8.7 100 6.9 LDR 1 50 12.2 70 11.5 1 85 10.0 1 100 9.5 1 100 8.0 100 6.4 LDR 2 50 11.3 70 10.5 85 9.2 100 8.81 100 7.4 100 5.8 LDR 2.9 50 10.7 70 10.0 85 8.8 95 8.1 100 7.0 100 5.6 MDR 4.3 50 10.2 70 9.6 80 8.1 95 7.8 100 6.7 100 5.3 MDR 7.3 50 9.2 65 8.4 80 7.4 95 7.0 100 6.0 100 4.8 MDR 10.9 50 8.7 65 7.9 80 6.9 90 6.4 100 5.7 100 4.5 MDR 14.5 501 8.2 65 7.4 80 6.5 90 6.0 100 5.4 100 4.3 HDR 24 50 6.7 65 6.1 75 5.1 90 4.9 95 1 4.3 100 3.5 HDR 43 50 5.3 65 4.7 75 4.0 85 3.8 951 3.4 100 2.7 N. Corn 50 5.3 60 4.5 75 4.0 85 3.8 95 3.4 100 2.7 G. Corn 50 4.7 60 4.1 75 3.6 85 3.4 90 2.9 1001 2.4 O.P./Com 50 4.2 60 3.71 70 3.1 80 2.9 90 2.6 100 2.2 Limited 1. 50 4.2 60 3.7 701 3.1 1 80 2.9 90 2.6 100 2.2 General I. _____ 50 3.7 60 3.2 701 2.71 80 2.6 90 2.3 100 1.9 *See Table 3-1 for more detailed description 3-12 EQUATION LE Feet - (11.9L3\0.385 Ic - ___ AE —5000 Ic = Time of concentration (hours) - I Watercourse Distance (miles) -4001) 1E Change In elevation along - effective slope line (See Figure 3-5) (feet) 3000 Tc - Hours Minutes —2000 4— —240 • 3— —180 —1000 - -900 &oo 2— —120 -7.00 _180 —90 500\ —400 \ 70 • 1--60 —300 —50 —200 —40 I - Miles Foot —30 1 —100 - -40M -20 - —18 - - - 3000 —16 —50 05— —14 —40 2000 12 - —1900 30 —1600 \ —10 —1400 \ —9 —1200 —20 —1000 —7 —900 —800 -700 —600 - —10 500 4 —400 300 —5 - 200 L Tc. SOURCE: Calito?nia Division of Highways (1041) and Kiipich (1940) FIGURE Nomograph for Determination of Time of Concentration (ic) or Travel Time (TI) for Natural Watersheds 31.4 S . County of San Diego Hydrology Manual Rainfall Isopluvials 100 Year Rainfall Event -24 Hours IsopIuvial (inches) 61 T— sip 71 47 tLH iiii CARLSeAD 10 0 5 ----- ----:"50----- CNITAS - sotANAEEAO V,v L. -J S110,00 - e-e• -_______ DJECTSITE = 5.1 in ___ OEUMA I A ---v--- - ___ trth±t LHdLEEi- - .- -- : - - - San Diego County Rational Hydrology Program CIVILCADD/CIVILDESIGN Engineering Software, (c)1991-2012 version 7.9 Rational method hydrology program based on San Diego County Flood Control Division 2003 hydrology manual Rational Hydrology Study Date: 01/16/18 ------------------------------------------------------------------------ oakmont of Carlsbad ------------------------------------------------------------------------ Hydrology Study control Information Program License Serial Number 6301 ------------------------------------------------------------------------ Rational hydrology study storm event year is 100.0 English (in-lb) input data Units used Map data precipitation entered: 6 our, precipitation(inches) = 2.800 24 hour precipitation(inches) = 5.100 P6/P24 = 54.9% San Diego hydrology manual 'C' values used Process from Point/Station 1.000 to Point/Station 2.000 INITIAL AREA EVALUATION Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [HIGH DENSITY RESIDENTIAL (24.0 DU/A or Less ) Impervious value, Ai = 0.650 Sub-Area C value = 0.710 Initial subarea total flow distance = 330.000(Ft.) Highest elevation 60.000(Ft.) Lowest elevation = 54.500(Ft.) Elevation difference = 5.500(Ft.) Slope = 1.667 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 75.00 (Ft) for the top area slope value of 1.67 %, in a development type of 24.0 DU/A or Less In Accordance with Figure 3-3 Initial Area Time of Concentration = 5.13 minutes TC = [1.8(1.1_C)*distance(Ft.)A.5)/(% slopeA(1/3)] TC = [1.8*(1.1_0.7100)( 75.000A.5)/( 1.667A(1/3)1= 5.13 Rainfall intensity (I) = 7.259(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KCIA) is C = 0.710 Subarea runoff = 6.648(CFS) Total initial stream area = 1.290(Ac.) +++++++++++++++++++.++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 2.000 to Point/Station 5.000 PIPEFLOW TRAVEL TIME (Program estimated size) Upstream point/station elevation = 54.500(Ft.) Downstream point/station elevation = 50.100(Ft.) Pipe length = 340.00(Ft.) Slope = 0.0129 Manning's N = 0.013 No. of pipes = 1 Required pipe flow = 6.648(CFS) Nearest computed pipe diameter = 15.00(In.) Calculated individual pipe flow = 6.648(CFS) Normal flow depth in pipe = 11.18(In.) Flow top width inside pipe = 13.07(In.) Critical Depth = 12.45(In.) Pipe flow velocity = 6.78(Ft/s) Travel time through pipe = 0.84 mm. Time of concentration (TC) = 5.96 mm. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 2.000 to Point/Station 5.000 SUBAREA FLOW ADDITION Rainfall intensity (I) = 6.585(In/Hr) for a 100.0 year storm Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [HIGH DENSITY RESIDENTIAL (24.0 DU/A or Less ) Impervious value, Al = 0.650 SUE-Area c value = 0.710 Time of concentration = 5.96 mm. Rainfall intensity = 6.585(In/Hr) for a 100.0 year storm Effective runoff coefficient used for total area (Q=KcIA) is C = 0.710 CA = 2.130 Subarea runoff = 7.378(CFS) for 1.710(Ac.) Total runoff = 14.026(CFS) Total area = 3.000(Ac.) ++++++++++++++.+++++++++++++++++++++++++++++++++++++++++++++++++++++-+ Process from Point/Station 3.000 to Point/Station 5.000 CONFLUENCE OF MINOR STREAMS Along Main Stream number: 1 in normal stream number 1 Stream flow area = 3.000(Ac.) Runoff from this stream = 14.026(CFS) Time of concentration = 5.96 mm. Rainfall intensity = 6.585(In/Hr) ++++++++++++++++.++++++++++++++++++++++++++++++++++++++++++++.+++++++ + Process from Point/Station 3.000 to Point/Station 4.00C INITIAL AREA EVALUATION Decimal fraction soil group A = 0.000 Decimal fraction soil group B = 0.000 Decimal fraction soil group C = 0.000 Decimal fraction soil group D = 1.000 [HIGH DENSITY RESIDENTIAL (24.0 DU/A or Less ) Impervious value, Al = 0.650 Sub-Area C value = 0.710 Initial subarea total flow distance = 490.000(Ft.) Highest elevation = 60.000(Ft.) Lowest elevation = 58.000(Ft.) Elevation difference = 2.000(Ft.) Slope = 0.408 % INITIAL AREA TIME OF CONCENTRATION CALCULATIONS: The maximum overland flow distance is 50.00 (Ft) for the top area slope value of 0.41 %, in a development type of 24.0 DLJ/A or Less In Accordance with Figure 3-3 Initial Area Time of Concentration = 6.69 minutes TC = [1.8(1.1_C)*distance(Ft.)A. 5)/C slopeA(1/3)] TC = [1.8*(1.1_0.7100)( 50.000A.5)/( 0.408A(1/3)]= 6.69 Rainfall intensity (I) = 6.112(In/Hr) for a 100.0 year storm Effective runoff coefficient used for area (Q=KcIA) is C = 0.710 subarea runoff = 11.457(CFS) Total initial stream area = 2.640(Ac.) +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++± Process from Point/Station 4.000 to, Point/Station 5.000 PIPEFLOW TRAVEL TIME (Program estimated size) Upstream point/station elevation = 55.000(Ft.) Downstream point/station elevation = 50.100(Ft.) Pipe length = 405.00(Ft.) Slope = 0.0121 Mannings N = 0.013 No. of pipes = 1 Required pipe flow = 11.457(CFS) Nearest computed pipe diameter = 18.00(In.) Calculated individual pipe flow = 11.457(CFS) Normal flow depth in pipe = 14.63(in.) Flow top width inside pipe = 14.05(in.) Critical Depth = 15.48(In.) Pipe flow velocity = 7.45(Ft/s) Travel time through pipe = 0.91 mm. Time of concentration (TC) = 7.60 mm. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Process from Point/Station 4.000 to Point/Station 5.000 CONFLUENCE OF MINOR STREAMS Along Main Stream number: 1 in normal stream number 2 Stream flow area = 2.640(Ac.) Runoff from this stream = 11.457(CFS) Time of concentration = 7.60 mm. Rainfall intensity = 5.632(In/Hr) Summary of stream data: Stream Flow rate TC Rainfall Intensity No. (Cr5) (mm) (In/Hr) 1 14.026 5.96 6.585 2 11.457 7.60 5.632 Qmax(1) = 1.000 ' 1.000 * 14.026) + 1.000 * 0.785 * 11.457) + = 23.018 Qeax (2) 0.855 * 1.000 * 14.026) + 1.000 1.000 * 11.457) + = 23.454 Total of 2 streams to confluence: Flow rates before confluence point: 14.026 11.457 Maximum flow rates at confluence using above data: 23.018 23.454 Area of streams before confluence: 3.000 2.640 Results of confluence: Total flow rate = 23.454(crs) Time of concentration = 7.598 mm. Effective stream area after confluence = 5.640(Ac.) End of computations, total study area = 5.640 (Ac.) -5..-...' /S '1\ ).4• )'_5 ) aoiE_0'it SN \ \ 3 7 \\ \ \ -t'A l .•1050 _- DETAIL '4 arm met SEE SHEET No. 4 ACZT 12.DrJ D701EYITL?EH LOT21O &ActT7Eim a r trans 97uv.rufa a Raw I s7.in7mainmm7mntPaaE Ds .70271 E 14°l fucammy Fnt &7004 Lwflllavntz ma MA mrs io PIWILMM IV RAM a aDztrmmgr,isn, a7Y&r esrA RMAn REnt 70 MAO' MW WIMP AM AWOIFO04Y almimw: -- ---- ==________________ -- ---- Ilwiri * * CON ?T5 "AsBuur 1DMADWA4TAh1WM?AEMEVW DEY4O AMtT 70 L F J IØ.70IIVTAL 47Y4L 9IEYY7070 DETE a woas 0mm IV 11mThT a uj. a m ToTal INSPECTOR DATE anoint MAmMAL 0*1000 aTe isa - . S OAKMONT OF CARLSBAD \ . DEVELII LIED LI NDITI N LIYDRLI UI GY ....... SO SO .... ...CUUULA1t I. FREQUENCY 1—M I(n5flJ AREA ,LENVH (FT) ROAD R/W 0 ,,BASIN 1A InT All RE ARANDONAD' BASIN 2A LBA T IJ' SN'3\\ ,I I BUILDI \\ \ \ I F ZU,7 AQOEN \\C\ \ \ -%J 7 4972 INs \\ SCALE 4u 2D 40 D 40 PLANS PREPARED BY PLANS PREPARED FOR. PROPERTY OWNER: SHEET CITY OF CARLSBAD 101ET AL ANCE IS SOY OR LAO EU EU DOTED ON ERLDT OESCRWTSO PT RU ROT DO OP ENYROL 00 0000 510 ON S0000 005 OAKMONT OF CARLSBAD ALLIANCE Ni 9005 17501 Nil—DEAR STREET 9200 OLD RAOW500 HWY. SUITE 200 L00000RIL IN SJ0000LX NORTH DOE OF PALOSSAR AIRPORT ROAD. SWEET 220 CENSC00000 RUNT DEVELOPED CONDITION I IYDROLOG',' LDDOORO TOSREISIW TEE TOLl 0-50 RU0O ,. 7RE C Ho OF / ADDRF I SAlT CARPET 1 05 RECORDEROS I p0 'p5HANNAH OAUGH— 1 1 SAN DIEGO COUNTY PLAN PREPARATION DOTE 07/10/17