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HomeMy WebLinkAboutPD 2023-0012; VALLEY MIDDLE SCHOOL CAMPUS MODERNIZATION; HYDROLOGY AND HYDRAULICS STUDY FOR VALLEY MIDDLE SCHOOL CAMPUS MODERNIZATION; 2024-01-24PLSA #3483 January 2024 HYDROLOGY AND HYDRAULICS STUDY FOR VALLEY MIDDLE SCHOOL – CAMPUS MODERNIZATION PD2023-0012 / GR2023-0021 / DWG 542-9A 1645 MAGNOLIA AVENUE CARLSBAD, CA 92008 PREPARED FOR: VALLEY MIDDLE SCHOOL 1645 MAGNOLIA CARLSBAD, CA 92008 PREPARED: APRIL 2023 REVISED: JULY 2023 FINAL: JANUARY 2024 PREPARED BY: 27127 CALLE ARROYO, SUITE 1904 SAN JUAN CAPISTRANO, CA 92675 949-661-6695 ________________________________________01/24/2024______ WILLIAM J. SUITER, RCE 68964 DATE 3/11/24 PASCO LARET SUITER & ASSOCIATES CIVIL ENGINEERING+ LAND PLANNING+ LAND SURVEYING PLSA #3483 January 2024 TABLE OF CONTENTS SECTION Executive Summary 1.0 Introduction 1.1 Existing Conditions 1.2 Proposed Project 1.3 Preliminary Hydrology Calculations 1.4 Conclusions 1.5 References 1.6 Methodology 2.0 Introduction 2.1 County of San Diego Criteria 2.2 City of Carlsbad Standards 2.3 Runoff Coefficient Determination 2.4 Hydrology Model Output 3.0 Pre-Developed Hydrologic Model Output (100-Year Event) 3.1 Post-Developed Hydrologic Model Output (100-Year Event) 3.2 Appendices Isopluvial Map A Runoff Coefficients B Hydrologic Soil Group C Site Pre- and Post-Development Hydrology Maps D Site Pre- and Post-Development AES Output E PLSA #3483 January 2024 1.0 EXECUTIVE SUMMARY 1.1 Introduction This Hydrology Study for Valley Middle School and 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 storm drain facilities and storm drain piping necessary for the storm drain treatment bypass to safely convey the runoff from the 100- year rainfall event. 1.2 Existing Conditions The project site is located at 1645 Magnolia Avenue. The project site area to be developed is located at the northern area of the Valley Middle School campus. The existing project site areas are mostly currently school courtyards between existing buildings consisting of concrete walkways and turf landscaping. The large courtyard area associated with DMA 1 currently surface drains southwesterly, being collected in various area drains, and being conveyed downstream south within storm drain pipes to confluence with a large public 54” storm drain pipe, per DWG 273-7, running along the west property line of the property. The small courtyard area associated with DMA 2 is adjacent to Magnolia Avenue, which is the school’s main entrance, consists of concrete walkways and turf landscaping. This area currently surface drains northwesterly toward Magnolia Avenue, which is ultimately collected in a public inlet that is tributary to the above public 54” storm drain pipe. According to Receiving Water and Conveyance Systems Exempt from Hydromodification Management Requirements for Carlsbad Watershed Management Area (refer to Attachment 2), the school’s campus drains into an existing conveyance system that is exempt from hydromodification. The public storm drain system is tributary to Agua Hedionda Lagoon, which is hydromodification exempt, and ultimately to the Pacific Ocean. 1.3 Proposed Project The proposed project consists of the reconfiguration of concrete walkways, stairs and ramps within two school courtyards, as well as various locations of existing concrete walkways to be removed and replaced in kind to fix ADA issues. The southern courtyard, DMA 1, will include tiered seat walls, ramps, and walkways that will surface drain to adjacent area drains, connecting to the existing storm drain system running south. Once downstream of the walkway improvements, a proposed proprietary stormwater treatment unit, Modular Wetland, is proposed. The unit is sized to treat the associated disturbed landscaping and new impervious walkways and walls, while not including the existing impervious walkways that are being removed and replaced for ADA compliance reasons. The northern courtyard, DMA 2, will surface drain to a series PLSA #3483 January 2024 of tree wells, which will treat and partially retain. The proposed project’s drainage infrastructure will not significantly alter the existing site’s drainage patterns. 1.4 Conclusions The proposed project and proposed storm drain are designed to safely convey the 100- year storm runoff flow. Hydrologic Basin 1 improvements will reduce the overall impervious area, resulting in a lower 100-year peak flow rate compared to the existing condition. Basin 1 design includes storm drain piping to a Modular Wetland System for treatment, which will be designed to convey said post peak flow. Hydrologic Basin 2 improvements will increase the impervious area, resulting in a slightly larger 100-year peak flow rate compared to the existing treatment. Basin 2 area drains overland to a series of tree wells, which will partially retain this stormwater volume. These will ensure that the discharge from the project site is of the best possible quality and will not pose any significant impact or threats to the water quality of the Pacific Ocean. In addition, the proposed development and storm drain improvements will not significantly alter the existing drainage patterns. It is with these above reasons that it can be concluded that there will be no negative impact to the downstream storm drain facilities or an increased potential of flooding. 1.5 References “San Diego County Hydrology Manual”, revised June 2003, County of San Diego, Department of Public Works, Flood Control Section. PLSA #3483 January 2024 2.0 METHODOLOGY 2.1 Introduction The hydrologic model used to perform the hydrologic analysis presented in this report utilizes the Rational 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: I = 7.44 x P6 x D-0.645 Where: I = Intensity (in/hr) P6 = 6-hour precipitation (in) D = duration (min – use Tc) Using the Time of Concentration (Tc), 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: Q = CIA Where: Q= flow (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/hr) A = drainage area contributing to the basin (ac) 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 that 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. 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). 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 PLSA #3483 January 2024 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 concentration to lengths under 100 feet and is dependent on land use and slope. 2.3 City of Carlsbad Standards The City of Carlsbad has additional requirements for hydrology reports which are outlined in the Engineering Standards, Volume 1: General Design Standards, 2022 Edition. The City of Carlsbad has additional BMP requirements which are outlined in the Engineering Standards, Volume 5: Carlsbad BMP Design Manual. Please refer to these manuals for further details. 2.4 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. Weighted runoff coefficients were calculated based on the existing and proposed impervious areas for each basin per the County Hydrology Manual section 3.1.2. See section 3.0 for calculations. PLSA #3483 January 2024 3.0 HYDROLOGY MODEL OUTPUT Rational Method Parameters Runoff Coefficient C= 0.9 x (% Impervious) + Cp (1-% Impervious) * Cp=0.25* for existing condition pervious type “B” soils 100-Year, 6-Hour Storm Precipitation (P6)=2.6 in (see rainfall isopluvial *) I= Intensity in/hr, I=7.44 x P6 x D-0.645 * Duration (D)= Time of Concentration, Tc Q=Peak Runoff, Q=C x I x A (cfs) *From San Diego County Hydrology Manual, June 2003 Revision 3.1 Pre-Developed Hydrologic Model Output (100-Year Event) BASIN 1A (Southern Courtyard) Total Basin Area = 2,707 sf (0.06 acres) Existing Impervious Area = 2,146 sf (79.27%) CPRE = (0.7927* 0.9) + (0.2072*0.25) CPRE =0.76 Q100=0.31 cfs BASIN 1B (Southern Courtyard) Total Basin Area = 77,305 sf (1.78 acres) Existing Impervious Area = 52,163 sf (67.47%) CPRE = (0.6747* 0.9) + (0.3252*0.25) CPRE =0.69 Q100=7.07 cfs BASIN 2 (Northern Courtyard) Total Basin Area = 7,010 sf (0.16 acres) Existing Impervious Area = 1,712 sf (24.44%) CPRE = (0.2444* 0.9) + (0.7556*0.25) CPRE =0.41 Q100=0.38 cfs See attached AES output. PLSA #3483 January 2024 3.2 Post-Developed Hydrologic Model Output (100-Year Event) BASIN 1A (Southern Courtyard) Total Basin Area = 2,801 sf (0.07 acres) Subarea Impervious Area = 1,893 sf (66.51%) CPOST = (0.6651* 0.9) + (0.3349*0.25) CPOST =0.68 Q100=0.29 cfs BASIN 1B (Southern Courtyard) Total Basin Area = 77,210 sf (1.77 acres) Subarea Impervious Area = 53,512 sf (69.31%) CPOST = (0.6931* 0.9) + (0.3069*0.25) CPOST =0.70 Q100=6.46 cfs BASIN 2 (Northern Courtyard) Total Basin Area = 7,010 sf (0.16 acres) Subarea Impervious Area = 2,090 sf (29.81%) CPOST = (0.2981* 0.9) + (0.7019*0.25) CPOST =0.44 Q100=0.40 cfs See attached AES output. Table 1: Summary of 100-year Peak Discharge Rates Existing Proposed Net Change Drainage Basin Area (ac) Q100 (cfs) Drainage Basin Area (ac) Q100 (cfs) Net Q100 (cfs) 1 – South 1.84 7.07 1 – South 1.84 6.46 -0.61 2 – North 0.16 0.38 2 – North 0.16 0.40 +0.02 Total 2.00 7.45 Total 2.00 6.78 -0.67 PLSA #3483 January 2024 APPENDIX A – ISOPLUVIAL MAP County of San Diego Hydrology Manual • Rai,ifall Isopluvials 100 Year Rainfall Event • 6 Hours lsopluvlal (Inches) N ™IS MAP IS PROVIDED WITHOUTWARR#ITY OF ANY KIND. El™~EXPRESS + ORIMPLIED,INCLUDING.BUTNOTLIMITEOTO,THEIMPLIEDWA~TIES OF MERCHANT,1BILITY AND FITNESS FORA PI\RTICUlAR PURPOSI:. C!ipyilghlS!PGiS.AII R/g~ll!i~- Thl111 _-11i111 !l)lly 1111dlil1 l11billl1d!H lll!lm lilll SAN DAG RNgliH!III llfll11mlll!!i•S]!tbmwhl1hi!11111i!llba~-iwllll1Piih1 Wiffilll p.-ml111111ll i!illSANDAG. Thl111pm:IJlll11W¥-illlllldHrlll■1y,il!llflt"abal-fiillM:!i!Mlwlh p:nnlllllllgflldld~ThllllllllaBlfliilllll!ftlMIPII. 3 Miles I PLSA #3483 January 2024 APPENDIX B – RUNOFF COEFFICIENTS San Diego County Hydrology Manual Section: 3 Date: June 2003 Page:6 of 26 Table 3-1 RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use Runoff Coefficient “C” Soil Type NRCS Elements County Elements % IMPER.A B C D Undisturbed Natural Terrain (Natural) Permanent Open Space 0*0.20 0.25 0.30 0.35 Low Density Residential (LDR) Residential,1.0 DU/A or less 10 0.27 0.32 0.36 0.41 Low Density Residential (LDR) Residential,2.0 DU/A or less 20 0.34 0.38 0.42 0.46 Low Density Residential (LDR) Residential,2.9 DU/A or less 25 0.38 0.41 0.45 0.49 Medium Density Residential (MDR) Residential,4.3 DU/A or less 30 0.41 0.45 0.48 0.52 Medium Density Residential (MDR) Residential,7.3 DU/A or less 40 0.48 0.51 0.54 0.57 Medium Density Residential (MDR) Residential,10.9 DU/A or less 45 0.52 0.54 0.57 0.60 Medium Density Residential (MDR) Residential,14.5 DU/A or less 50 0.55 0.58 0.60 0.63 High Density Residential (HDR) Residential, 24.0 DU/A or less 65 0.66 0.67 0.69 0.71 High Density Residential (HDR) Residential, 43.0 DU/A or less 80 0.76 0.77 0.78 0.79 Commercial/Industrial (N. Com)Neighborhood Commercial 80 0.76 0.77 0.78 0.79 Commercial/Industrial (G. Com)General Commercial 85 0.80 0.80 0.81 0.82 Commercial/Industrial (O.P. Com)Office Professional/Commercial 90 0.83 0.84 0.84 0.85 Commercial/Industrial (Limited I.) Limited Industrial 90 0.83 0.84 0.84 0.85 Commercial/Industrial (General I.) General Industrial 95 0.87 0.87 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 PLSA #3483 January 2024 APPENDIX C – HYDROLOGIC SOIL GROUP CLASSIFICATION Hydrologic Soil Group—San Diego County Area, California Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/6/2022 Page 1 of 4 36 6 8 6 5 0 36 6 8 7 1 0 36 6 8 7 7 0 36 6 8 8 3 0 36 6 8 8 9 0 36 6 8 9 5 0 36 6 9 0 1 0 36 6 8 6 5 0 36 6 8 7 1 0 36 6 8 7 7 0 36 6 8 8 3 0 36 6 8 8 9 0 36 6 8 9 5 0 36 6 9 0 1 0 469020 469080 469140 469200 469260 469320 469380 469440 469500 469560 469020 469080 469140 469200 469260 469320 469380 469440 469500 469560 33° 9' 34'' N 11 7 ° 1 9 ' 5 6 ' ' W 33° 9' 34'' N 11 7 ° 1 9 ' 3 4 ' ' W 33° 9' 22'' N 11 7 ° 1 9 ' 5 6 ' ' W 33° 9' 22'' N 11 7 ° 1 9 ' 3 4 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 11N WGS84 0 100 200 400 600Feet 0 35 70 140 210Meters Map Scale: 1:2,600 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. USDA = MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: San Diego County Area, California Survey Area Data: Version 16, Sep 13, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jan 24, 2020—Feb 12, 2020 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. Hydrologic Soil Group—San Diego County Area, California Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/6/2022 Page 2 of 4USDA = □ D D D D D D D D ,,..,,,. ,,..,,,. □ ■ ■ □ □ ,,..._, t-+-t ~ tllWI ,..,,. ~ • Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI CgC Chesterton-Urban land complex, 2 to 9 percent slopes D 0.3 2.4% MlC Marina loamy coarse sand, 2 to 9 percent slopes B 12.3 97.6% Totals for Area of Interest 12.6 100.0% 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 (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Hydrologic Soil Group—San Diego County Area, California Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/6/2022 Page 3 of 4USDA = Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—San Diego County Area, California Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 4/6/2022 Page 4 of 4~ PLSA #3483 January 2024 APPENDIX D – HYDROLOGY MAPS "' • .,, x w 6 "' ~ I I ! • a. C " >, 8' e "R I w " <( z ~ a: ~ <( " f-g a. ~ <( " !l! <( SD \ '" -so -so .-_tJ ,t. I ~ t ~--l I I EX. BLDG 700 I G) \ \ -t. / // '\ I I G>I ! \ FG.=163.6 -~ > EX.ADMIN BLDG 900 EXISTING HYDROLOGY MAP EX. MPR BLDG VALLEY MIDDLE SCHOOL EX. BLDG 200 ~\ ' .._, . I \I\\\ I I ,r I \ I I II \I d,rl-i..i. I 11 1 " \ ~ I \ \ \ I I \ \ . ' \ \ \ \ I . IINJl..-tr I ,__,_,,..., ( I w++.-\ ';--t't~~'-.\ EX. BLDG 1200 \ I I I I I \ I I \ \ \ I < \ --- LEGEND: [j]QJ ( 1.0AC EL.=1555.0 IE.=1555.0 I . . . . . . . ... ' .... . . . ' ---SD ) <I _, - MAJOR-BASIN BOUNDARY HYDROLOGIC NODE HYDROLOGIC AREA ELEVATION AT NODE INVERT ELEVATION AT NODE LIMITS OF EX. BUILDING LIMITS OF EX. CONCRETE/PAVEMENT STREET CENTERLINE STREET RIGHT OF WAY UNDERGROUND PIPE DRAINAGE PATH EX. STORM DRAINAGE PIPE FLOW PATH PASCO LARET SUITER I ffe.~~«Jlt!ffe.llE~ San Diego I Solana Beach I Orange County Phone 949.661.6695 I www.plsaengineering.com SCALE: 1" = 30' ,__j -~ i i 30 15 0 30 60 90 VALLEY MIDDLE SCHOOL PD2023-0012 I GR2023-0021 EXISTING HYDROLOGY MAP PLSA JOB NO.3483 SCALE 1 '=30' 01-24-2024 SHEET 1 OF 1 (/)---------------------------------------------------------------------------------------------------------------------------------------------------- "' • "C a: 0 0: a. 6 0: 5' I ,), ! • Q. C ::, >, g' 0 "R I ~ <( C >- '3 a. ~ <( C '!;! <( Cl) I / I I I -----/ -SD SD EX. BLDG 600 EX. BLDG 600A ...... '" "' EX. BLDG 700 I \ I ...... ---- / ,.- / I I I I I ,,,--r_--/ / -,-/ / ~ / /_Lr,_/ / ,,,. / / ,,, I / I I I -...... ' L_ -.. -- PROPOSED HYDROLOGY MAP EX. MPR BLDG VALLEY MIDDLE SCHOOL '\ - I \ I 1➔11 \1 I ' vl-Li/11, EX. BLDG 1200 I \ I I \ LEGEND: [IQQ] ( 1.0AC ) EL.=1555.0 IE.=1555.0 ---SD --so _, - MAJOR-BASIN BOUNDARY HYDROLOGIC NODE HYDROLOGIC AREA ELEVATION AT NODE INVERT ELEVATION AT NODE LIMITS OF EX. BUILDING LIMITS OF EX. OR PROP. CONCRETE/PAVEMENT STREET CENTERLINE STREET RIGHT OF WAY UNDERGROUND PIPE DRAINAGE PATH EX. STORM DRAINAGE PIPE PROP. STORM DRAINAGE PIPE FLOW PATH PASCO LARET SUITER I ffe.~~©t!ffe.iilE~ San Diego I Solana Beach I Orange County Phone 949.661.6695 I www.plsaengineering.com VALLEY MIDDLE SCHOOL PD2023-0012 I GR2023-0021 PROPOSED HYDROLOGY MAP PLSA JOB NO.3483 SCALE 1 "=30' 01-24-2024 SHEET 1 OF 1 PLSA #3483 January 2024 APPENDIX E – HYDROLOGY CALCULATIONS ____________________________________________________________________________ **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-2016 Advanced Engineering Software (aes) Ver. 23.0 Release Date: 07/01/2016 License ID 1452 Analysis prepared by: PASCO LARET SUITER & ASSOCIATES 27127 Calle Arroyo, Suite 1904, San Juan Capistrano, CA 92675 ph 949.661.6695 plsaengineering.com ---------------------------------------------------------------------------- FILE NAME: 3483PRE.DAT TIME/DATE OF STUDY: 11:30 04/03/2023 ---------------------------------------------------------------------------- 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 MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING 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 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 100.00 TO NODE 110.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< ============================================================================ *USER SPECIFIED(SUBAREA): OFFICE PROFESSIONAL/COMMERCIAL RUNOFF COEFFICIENT = .7600 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 73.00 UPSTREAM ELEVATION(FEET) = 163.60 DOWNSTREAM ELEVATION(FEET) = 162.90 ELEVATION DIFFERENCE(FEET) = 0.70 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.774 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 59.18 (Reference: Table 3-1B of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.850 NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE. SUBAREA RUNOFF(CFS) = 0.31 TOTAL AREA(ACRES) = 0.06 TOTAL RUNOFF(CFS) = 0.31 **************************************************************************** FLOW PROCESS FROM NODE 110.00 TO NODE 120.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 161.00 DOWNSTREAM(FEET) = 154.10 FLOW LENGTH(FEET) = 409.00 MANNING'S N = 0.015 DEPTH OF FLOW IN 6.0 INCH PIPE IS 3.0 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 3.17 ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.31 PIPE TRAVEL TIME(MIN.) = 2.15 Tc(MIN.) = 6.93 LONGEST FLOWPATH FROM NODE 100.00 TO NODE 120.00 = 482.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 120.00 TO NODE 120.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< ============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.552 *USER SPECIFIED(SUBAREA): OFFICE PROFESSIONAL/COMMERCIAL RUNOFF COEFFICIENT = .6900 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT = 0.6923 SUBAREA AREA(ACRES) = 1.78 SUBAREA RUNOFF(CFS) = 6.82 TOTAL AREA(ACRES) = 1.8 TOTAL RUNOFF(CFS) = 7.07 TC(MIN.) = 6.93 **************************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 210.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< ============================================================================ *USER SPECIFIED(SUBAREA): OFFICE PROFESSIONAL/COMMERCIAL RUNOFF COEFFICIENT = .4100 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 150.00 UPSTREAM ELEVATION(FEET) = 167.00 DOWNSTREAM ELEVATION(FEET) = 158.30 ELEVATION DIFFERENCE(FEET) = 8.70 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.616 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 91.60 (Reference: Table 3-1B of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.718 SUBAREA RUNOFF(CFS) = 0.38 TOTAL AREA(ACRES) = 0.16 TOTAL RUNOFF(CFS) = 0.38 ============================================================================ END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 0.2 TC(MIN.) = 6.62 PEAK FLOW RATE(CFS) = 0.38 ============================================================================ ============================================================================ END OF RATIONAL METHOD ANALYSIS ____________________________________________________________________________ **************************************************************************** RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT 2003,1985,1981 HYDROLOGY MANUAL (c) Copyright 1982-2016 Advanced Engineering Software (aes) Ver. 23.0 Release Date: 07/01/2016 License ID 1452 Analysis prepared by: ---------------------------------------------------------------------------- FILE NAME: 3483POST.DAT TIME/DATE OF STUDY: 15:47 01/24/2024 ---------------------------------------------------------------------------- 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 MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING 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 0.0312 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: 1. Relative Flow-Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top-of-Curb) 2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* **************************************************************************** FLOW PROCESS FROM NODE 100.00 TO NODE 110.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< ============================================================================ *USER SPECIFIED(SUBAREA): *USER SPECIFIED(SUBAREA): OFFICE PROFESSIONAL/COMMERCIAL RUNOFF COEFFICIENT = .6700 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 73.00 UPSTREAM ELEVATION(FEET) = 163.60 DOWNSTREAM ELEVATION(FEET) = 162.90 ELEVATION DIFFERENCE(FEET) = 0.70 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 6.038 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 59.18 (Reference: Table 3-1B of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.066 SUBAREA RUNOFF(CFS) = 0.28 TOTAL AREA(ACRES) = 0.07 TOTAL RUNOFF(CFS) = 0.28 **************************************************************************** FLOW PROCESS FROM NODE 110.00 TO NODE 120.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 161.00 DOWNSTREAM(FEET) = 154.50 FLOW LENGTH(FEET) = 409.00 MANNING'S N = 0.015 DEPTH OF FLOW IN 6.0 INCH PIPE IS 2.9 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 3.02 ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.28 PIPE TRAVEL TIME(MIN.) = 2.26 Tc(MIN.) = 8.30 LONGEST FLOWPATH FROM NODE 100.00 TO NODE 120.00 = 482.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 120.00 TO NODE 120.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< ============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.942 *USER SPECIFIED(SUBAREA): OFFICE PROFESSIONAL/COMMERCIAL RUNOFF COEFFICIENT = .7000 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT = 0.6989 SUBAREA AREA(ACRES) = 1.77 SUBAREA RUNOFF(CFS) = 6.12 TOTAL AREA(ACRES) = 1.8 TOTAL RUNOFF(CFS) = 6.35 TC(MIN.) = 8.30 **************************************************************************** FLOW PROCESS FROM NODE 200.00 TO NODE 210.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< ============================================================================ *USER SPECIFIED(SUBAREA): OFFICE PROFESSIONAL/COMMERCIAL RUNOFF COEFFICIENT = .4400 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 68.00 UPSTREAM ELEVATION(FEET) = 167.00 DOWNSTREAM ELEVATION(FEET) = 162.90 ELEVATION DIFFERENCE(FEET) = 4.10 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 5.383 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.532 SUBAREA RUNOFF(CFS) = 0.26 TOTAL AREA(ACRES) = 0.09 TOTAL RUNOFF(CFS) = 0.26 **************************************************************************** FLOW PROCESS FROM NODE 210.00 TO NODE 220.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 159.50 DOWNSTREAM(FEET) = 158.00 FLOW LENGTH(FEET) = 110.00 MANNING'S N = 0.015 DEPTH OF FLOW IN 6.0 INCH PIPE IS 2.9 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 2.81 ESTIMATED PIPE DIAMETER(INCH) = 6.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 0.26 PIPE TRAVEL TIME(MIN.) = 0.65 Tc(MIN.) = 6.03 LONGEST FLOWPATH FROM NODE 200.00 TO NODE 220.00 = 178.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 220.00 TO NODE 220.00 IS CODE = 81 ---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< ============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.068 *USER SPECIFIED(SUBAREA): OFFICE PROFESSIONAL/COMMERCIAL RUNOFF COEFFICIENT = .4400 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT = 0.4400 SUBAREA AREA(ACRES) = 0.06 SUBAREA RUNOFF(CFS) = 0.16 TOTAL AREA(ACRES) = 0.2 TOTAL RUNOFF(CFS) = 0.40 TC(MIN.) = 6.03 ============================================================================ END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 0.2 TC(MIN.) = 6.03 PEAK FLOW RATE(CFS) = 0.40 ============================================================================ ============================================================================ END OF RATIONAL METHOD ANALYSIS