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HomeMy WebLinkAboutPD 2021-0004; NORTH COUNTY ACADEMY; HYDROLOGY AND HYDRAULICS STUDY; 2021-05-01ESSi No. RCE 68964 EXP. 12-31-21 ) I) Civ\ Of c'-7 RECEIVED ND DEVELOPMENT ENGINEERING JUN 28 2021 HYDROLOGY AND HYDRAULICS ICS STUDY NORTH COUNTY ACADEMY - CAMPUS CONSOLIDATION PD2021-0004 / GP2021-0004 / DWG 529-4.A 1640 MAGNOLIA CARLSBAD, CA 92008 PREPARED FOR: NORTH COUNTY ACADEMY 1640 MAGNOLIA CARLSBAD, CA 92008 PREPARED: DECEMBER 2020 REVISED: MAY 2021 PREPARED BY: PASCO LARET SUITER & ASSOCIATES 27127 CALLE ARROYO, SUITE 1904 SAN JUAN CAPISTRANO, CA 92675 05/10/2021 WILLIAM. J. SITER, RCE 68964 DATE PLSA #3403 May 2021 TABLE OF CONTENTS SECTION Executive Summary 1.0 Introduction 1.1 Existing conditions 1.2 Proposed Project 1.3 Hydrornodification 1.4 Preliminary Hydrology Calculations 1.5 Conclusions 1.6 References 1.7 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 Volume Sizing 3.3 Post-Developed Mitigated 100-Year Hydrograph 3.4 Hydraulic Model Output 4.0 AES Pipetiow 4.1 Attachments 5.0 Isopluvial Map Runoff Coefficients Site Pro- and Post-Development Hydrology Maps Site Pro- and Post-Development AES Output Site Pro- and Post-Development Hydrographs PLSA #3403 May 2021 1.0 EXECUTIVE SUMMARY Li Introduction This Hydrology Study for the North County Academy 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 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 project site is located at 1640 Magnolia Avenue. The project site is currently a vacant grass field on the southeast corner of the school's campus, adjacent to a larger grass field to the east. The site drains to the north to an inlet that is a part of the school's storm drain facilities which connects at the southwest corner of the site to an 18-inch storm drain within Magnolia Avenue per PD 01-11. This public storm drain system is tributary to Agua Hedionda Lagoon, which is hydromodification exempt, and ultimately the Pacific Ocean. 1.3 Proposed Project The proposed project will include the construction of three side-by-side modular buildings, including two classrooms and a sensory room. Adjacent to the new elementary school aged classrooms is proposed hardscape, playground, as well as a shade structure. The site will drain to a single biofiltration basin at the south edge of the project site, which has a discharge pipe that extends north to an existing inlet currently draining the field. The proposed project's drainage infrastructure will not significantly alter the existing site's drainage patterns. The proposed storm drain system design includes a biofiltration basin, new PVC storm drain facilities, and swales. Runoff from the site will drain, to the proposed biofiltration BMP for water quality treatment and mitigation of the 100-year storm event runoff. Due to minimal percolation rates, stormwater will not infiltrate below the biofiltration basin. The proposed biofiltration basin has an emergency overflow inlet, that discharges to a cobble spreader to mimic the existing condition. 1.4 Hydromodification The site drains to the north to an inlet that is a part of the school's storm drain facilities and an 18-inch storm drain within Magnolia Avenue per PD 01-li. This public storm drain system is tributary to Agua Hedionda Lagoon, which is hydromodification exempt. PLSA#3403 May 2021 1.5 Preliminary Hydrology Calculations The existing 100-year peak discharge from the site is 0.38 cfs and is associated with a time of concentration (Tc) of 10 minutes and a total area of 0.24 acres. The post-developed condition peak discharge is 1.33 cfs and is associated with a Tc of 6 minutes and a total area of 0.25 acres. The biofiltration basin detains the difference in volume between the pre- and post-developed conditions. The mitigated 100-year peak discharge from the basin is 0.29 cfs. See sections 3.1 & 3.2. Pre-project Q100 (cfs) Un-Mitigated Post-Project Q100(cfs) Mitigated Post-Project Q100 (cfs) 0.38 1.33 I 0.29 1.6 Conclusions The proposed development and proposed storm drain is designed to safely convey the 100-year storm runoff flow and includes storm drain piping to a biofiltration basin to 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. The proposed biofiltration basin has been sized so that any increase in storm water runoff will be detained and will not increase the potential for flooding or create an increase in erosion. This project has been deemed a Priority Project, but because of its receiving water, the project is hydromodification exempt. 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. 1.7 References "San Diego county Hydrology Manual ", revised June 2003, County of San Diego, Department of Public Works, Flood Control Section. PLSA #3403 May 2021 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: 1= 7.44 x P x D-0M5 Where: I = intensity (inlhr) P6 = 6-hour precipitation (in) D = duration (mm - 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. infiltrationlevaporationiabsorptionletc) 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, 1, 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 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. PLSA#3403 May 2021 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, 2016 Edition. The City of Carlsbad has additional BM.P 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 #3403 May 2021 3.0 HYDROLOGY MODEL OUTPUT Rational Method Parameters Runoff Coefficient C= 0.9 x (% Impervious) + Cp (1-% Impervious) * Cp=0.35* for existing condition pervious type "1)" soils 100-Year, 6-Hour Storm Precipitation (P6)=2.6 in (see rainfall isopluvial *) 1= intensity in/hr, 1=7.44 x P6 x DOMs * 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 Total Basin Area = 10,606 sf (0.24 acres) Existing Pervious Area = 10,606 sf (100%) C= 1.0*0.35 CPRE-0.35 Qioo=0.38 cfs See attached AES output. 3.2 Post-Developed Hydrologic Model Output (100-Year Event) BASIN Total Basin Area = 10,595 sf (0,25 acres) Total Proposed Impervious Area = 8,535 sf Subarea I Total Subarea Area = 5,021 sf (0.10 acres) Subarea Impervious Area = 5,021 sf (100%) Cposr,i = (1.0* 0.9) + (0.0*0.35) Cposr,j = 0.90 Subarea 2 Total. Subarea Area = 5,574 sf (0.13 acres) Subarea Impervious Area = 3,514 sf (63.0%) Cposi2 = (0.63* 0.9) + (0•37*035) Cposr.2 = 0.70 CPOST.AVO = 0.90 (5.021/10,595) + 0.70 (5.574/10,595) CposT,Avc = 0.79 Q=1.33 cfs See attached AES output. PLSA#3403 May 2021 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: EXISTING / PRE-DEVELOPED HYDROLOGIC CONDITION FILE NAME: 3403PRE.DAT TIME/DATE OF STUDY: 15:37 05/03/2021 ---------------------------------------------------------------------------- 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 ANALYSIS *USER..DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING WIDTH CROSSFALL IN- I OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE! WAY (FT) (FT) (FT) (FT) (n) 1 30.0 20.8 0.018/0.018/0.020 8.67 2.00 8.0313 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS: Relative Flow-Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top-of-Curb) (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* FLOW PROCESS FROM NODE 1.00 TO NODE 2.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< USER-SPECIFIED RUNOFF COEFFICIENT = .3580 S.C.S. CURVE NUMBER (AMC II) = 80 INITIAL SUBAREA FLOW-LENGTH(FEET) 140.00 UPSTREAM ELEVATION(FEET) = 163.40 DOWNSTREAM ELEVATION(FEET) = 159.20 ELEVATION DIFFERENCE(FEET) = 4.20 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 9.361 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 100.00 (Reference: Table 3-1B of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Ic CALCULATION! 100 YEAR RAINFALL INIENSITY(INCH/HOtJR) = 4.571 SUBAREA RUNOFF(CFS) = 0.38 TOTAL AREA(ACRES) = 0.24 TOTAL RUNOFF(CFS) = 0.38 END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 0.2 TC(MIN.) = 9.36 PEAK FLOW RATE(CFS) = 0.38 END OF RATIONAL METHOD ANALYSIS Rational Method Hydrograph Calculations for North County Academy Existing Hydrology Condition Q= 038 cfs Tc= 10 min C= 0.35 #= 36 P= 2.6 in A= 0.24 acres (7.44*P6*1Y .645) (1*0160) (VI-VO) (3 V/A T) (QciA) (Re-ordered) D I VOL AVOL I(INCR) Q VOL ORDINATE # (MIN) (IN/HR) (IN) (IN) (IN/HR) (CFS) (CF) (CFS) 0 0 0.00 0.00 0.73 4.38 0.38 228 1 10 4.38 0.73 0.20 1.22 0.10 62 0.01 2 20 2.80 0.93 0.14 0.87 0.07 44 0.01 3 30 2.16 1.08 0.12 0.70 0.06 35 0.01 4 40 1.79 1.19 0.10 0.59 0.05 30 0.01 5 50 1.55 1.29 0.09 0.52 0.04 26 0.01 6 60 1.38 1.38 0.08 0.47 0.04 23 0.02 7 70 1.25 1.46 0.07 0.42 0.04 21 0.02 8 80 1.15 1.53 0.07 0.39 0.03 20 0.02 9 90 1.06 1.59 0.06 0.36 0.03 18 0.02 10 100 0.99 1.65 0.06 0.34 0.03 17 0.02 11 110 0.93 1.71 0.05 0.32 0.03 16 0.02 12 120 0.88 1,76 0.05 0.31 0.03 15 0.02 13 130 0.84 1.81 0.05 0.29 0.02 15 0.02 14 140 0.80 1.86 0.05 0.28 0.02 14 0.02 15 150 0.76 1.91 0.04 0.27 0.02 13 0.02 16 160 0.73 1.95 0.04 0.26 0.02 13 0.02 17 170 0.70 2.00 0.04 0.25 0.02 12 0.03 18 180 0.68 2.04 0.04 0.24 0.02 12 0.03 19 190 0.66 2.08 0.04 0.23 0.02 12 0.03 20 200 0.63 2.11 0.04 0.22 0.02 11 0.04 21 210 0.61 2.15 0.04 0.21 0.02 11 0.04 22 220 0.60 2.19 0.03 0.21 0.02 11 0.05 23 230 0.58 2.22 0.03 0.20 0.02 10 0.07 24 240 0.56 2.26 0.03 020 0.02 10 0.10 25 250 0.55 2.29 0.03 0.19 0.02 10 0.38 26 260 0.54 2.32 0.03 0.19 0.02 9 0.06 27 270 0.52 2.35 0.03 0.18 0.02 9 0.04 28 280 0.51 2.38 0.03 0.18 0.02 9 0.03 29 290 0.50 2.41 0.03 0.18 0.01 9 0.03 30 300 0.49 2.44 0.03 0.17 0.01 9 0.02 31 310 0.48 2.47 0.03 0.17 0.01 8 0.02 32 320 0.47 2.50 0.03 0.16 0.01 8 0.02 33 330 0.46 2.53 0.03 0.16 0.01 8 0.02 34 340 0.45 2.55 0.03 0.16 0.01 8 0.02 35 350 0.44 2.58 0.03 0.16 0.01 8 0.01 36 360 0.43 2.61 0.00 0.00 0.00 0 0.01 SUM= 795 cubic feet 0.02 acre-feet Hydrograph.xs 5/3/2021 Rational Method Hydrograph Calculations for North County Academy Existing Hydrology Condition Hydrographxs 5/3/2021 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: PROPOSED I POST-DEVELOPED HYDROLOGIC CONDITION ---------------------------------------------------------------------------- FILE NAME: 3403P05T.DAT TIME/DATE OF STUDY: 16:38 05/06/2021 ---------------------------------------------------------------------------- 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 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. (Fl) (Fl) SIDE / SIDE! WAY (FT) (IT) (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: Relative Flow-Depth = 0.00 FEET as (Maximum Allowable Street Flow Depth) - (Top-of-Curb) (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S) *SIZE PIPE WITH A FLOW CAPACITY GREATER THAN OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.* FLOW PROCESS FROM NODE 1.00 TO NODE 2.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT = .9000 S.C.S. CURVE NUMBER (AMC II) = 0 INITIAL SUBAREA FLOW-LENGTH(FEET) = 84.00 UPSTREAM ELEVATION(FEET) = 162.00 DOWNSTREAM ELEVATION(FEET) = 161.30 ELEVATION DIFFERENCE(FEET) = 0.70 SUBAREA OVERLAND TIME OF FLOW(MIN.) = 2.880 WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 56.67 (Reference: Table 3-1B of Hydrology Manual) THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.858 NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE. SUBAREA RUNOFF(CFS) = 0.74 TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.74 FLOW PROCESS FROM NODE 2.00 TO NODE 2.00 IS CODE = 22 -------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<< *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT = .9000 S.C.S. CURVE NUMBER (AMC II) = 0 USER SPECIFIED Tc(MIN.) = 5.000 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.850 SUBAREA RUNOFF(CFS) = 0.74 TOTAL AREA(ACRES) = 0.12 TOTAL RUNOFF(CFS) = 0.74 **************************************************************************** FLOW PROCESS FROM NODE 2.00 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) = 159.15 DOWNSTREAM(FEET) = FLOW LENGTH(FEET) = 36.00 MANNINGS N = 0.010 DEPTH OF FLOW IN 9.0 INCH PIPE IS 4.8 INCHES PIPE-FLOW VELOCITY(FEET/SEC..) = 3.12 ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = PIPE-FLOW(CFS) = 0.74 PIPE TRAVEL TIME(MIN.) = 0.19 Tc(MIN.) 5.19 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 3.00 = 1 FLOW PROCESS FROM NODE 3.00 TO NODE 3.00 IS CODE = 81 >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<< 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 6.686 *USER SPECIFIED(SUBAREA): USER-SPECIFIED RUNOFF COEFFICIENT = .7000 S.C.S. CURVE NUMBER (AMC II) = 0 AREA-AVERAGE RUNOFF COEFFICIENT = 0.7960 SUBAREA AREA(ACRES) = 0.13 SUBAREA RUNOFF(CFS) = 0.61 TOTAL AREA(ACRES) = 0.2 TOTAL RUNOFF(CFS) = 1.33 TC(MIN.) = 5.19 FLOW PROCESS FROM NODE 3.10 TO NODE 4.00 IS CODE = 31 >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<< >>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ELEVATION DATA: UPSTREAM(FEET) = 155.67 DOWNSTREAM(FEET) = 153.40 FLOW LENGTH(FEET) = 163.00 MANNINGS N = 0.010 DEPTH OF FLOW IN 9.0 INCH PIPE IS 4.7 INCHES PIPE-FLOW VELOCITY(FEET/SEC.) = 5.71 ESTIMATED PIPE DIAMETER(INCH) = 9.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.33 PIPE TRAVEL TIME(MIN.) = 0.48 Tc(MIN.) = 5.67 LONGEST FLOWPATH FROM NODE 2.00 TO NODE 4.00 = 283.00 FEET. END OF STUDY SUMMARY: TOTAL AREA(ACRES) = 0.2 TC(MIN.) = 5.67 PEAK FLOW RATE(CFS) = 1.33 END OF RATIONAL METHOD ANALYSIS 4' Rational Method Hydrograph Calculations for North County Academy Proposed Hydrology Condition Q2= 133 cfs Tc= 5 min C= 0.79 #= 72 P506 2.6 in A= 0.25 acres (7 44*p6*DA 645) (1*0/60) (VI-VO) (4 V/..i 7) (Q=ciA) (Re-ordered) D I VOL AVOL I (INCR) Q VOL ORDINATE # (MIN) (IN/HR) (IN) (IN) (IN/HR) (CFS) (CF) (CFS) 0 0 0.00 0.00 0.57 6.85 1.33 399 1 5 6.85 0.57 0.16 1.91 0.38 113 0.03 2 10 4.38 0.73 0.11 1.36 0.27 80 0.03 3 15 3.37 0.84 0.09 1.09 0.21 64 0.03 4 20 2.80 0.93 0.08 0.92 0.18 55 0.03 5 25 2.43 1.01 0.07 0.81 0.16 48 0.03 6 30 2.16 1.08 0.06 0.73 0.14 43 0.03 7 35 1.95 1.14 0.06 0.66 0.13 39 0.03 8 40 1.79 1.19 0.05 0.61 0.12 36 0,03 9 45 1.66 1.25 0.05 0.57 0.11 34 0.03 10 50 1.55 1.29 0.04 0.53 0.11 32 0.03 11 55 1.46 1.34 0.04 0.50 0.10 30 0.04 12 60 1.38 1.38 0.04 0.48 0.09 28 0.04 13 65 1.31 1.42 0.04 0.45 0.09 27 0.04 14 70 1.25 1.46 0.04 0.43 0.09 26 0.04 15 75 1.19 1.49 0.03 0.42 0.08 25 0.04 16 80 1.15 1.53 0.03 0.40 0.08 24 0.04 17 85 1.10 1.56 0.03 0.38 0.08 23 0.04 18 90 1.06 1.59 0.03 0.37 0.07 22 0.04 19 95 1.03 1.62 0.03 0.36 0.07 21 0.04 20 100 0.99 1.65 0.03 0.35 0.07 21 0.04 21 105 0.96 1.68 0.03 0.34 0.07 20 0.04 22 110 0.93 1.71 0.03 0.33 0.06 19 0.04 23 115 0.91 1.74 0.03 0.32 0.06 19 0.05 24 120 0.88 1.76 0.03 0.31 0.06 18 0.05 25 125 0.86 1.79 0.03 0.30 0.06 18 0.05 26 130 0.84 1.81 0.02 0.29 0.06 17 0.05 27 135 0.82 1.84 0.02 0.29 0.06 17 0.05 28 140 0.80 1.86 0.02 0.28 0.06 17 0.05 29 145 0.78 1.89 0.02 0.27 0.05 16 0.05 30 150 0.76 1.91 0.02 0.27 0.05 16 0.06 31 155 0.75 1.93 0.02 0.26 0.05 16 0.06 32 160 0.73 1.95 0.02 0.26 0.05 15 0.06 33 165 0.72 1.98 0.02 0.25 0.05 15 . 0.06 34 170 0.70 2.00 0.02 0.25 0.05 15 0.06 35 175 0.69 2.02 0.02 0.24 0.05 14 0.07 36 180 0.68 2.04 0.02 0.24 0.05 14 0.07 37 185 0.67 2.06 0.02 0.23 0.05 14 0.08 38 190 0.66 2.08 0.02 0.23 0.05 14 0.08 39 195 0.64 2.10 0.02 0.23 0.04 13 0.09 40 200 0.63 2.11 0.02 0.22 0.04 13 0.09 41 205 0.62 2.13 0.02 0.22 0.04 13 0.10 42 210 0.61 2.15 0.02 0.22 0.04 13 0.11 Hydregraph.xls 5/6/2021 Rational Method Hydrograph Calculations for North County Academy Proposed Hydrology Condition 43 215 0.61 2.17 0.02 0.21 0.04 13 0.12 44 220 0.60 2.19 0.02 0.21 0.04 12 0.13 45 225 0.59 2.21 0.02 0.21 0.04 12 0.16 46 230 0.58 2.22 0.02 0.20 0.04 12 0.18 47 235 0.57 2.24 0.02 0.20 0.04 12 0.27 48 240 0.56 2.26 0.02 0.20 0.04 12 0.38 49 245 0.56 2.27 0.02 0.20 0.04 12 1.33 50 250 0.55 2.29 0.02 0.19 0.04 11 0.21 51 255 0.54 2.31 0.02 0.19 0.04 11 0.14 52 260 0.54 2.32 0.02. 0.19 0.04 11 0.11 53 265 0.53 2.34 0.02 0.19 0.04 11 0.09 54 270 0.52 2.35 0.02 0.18 0.04 11 0.08 55 275 0.52 2.37 0.02 0.18 0.04 11 0.07 56 280 0.51 2.38 0.02 0.18 0.04 11 0.07 57 285 0.50 2.40 0.01 0.18 0.04 11 0.06 58 290 0.50 2.41 0.01 0.18 0.03 10 0.06 59 295 0.49 2.43 0.01 0.17 0.03 10 0.05 60 300 0.49 2.44 0.01 0.17 0.03 10 0.05 61 305 0.48 2.46 0.01 0.17 0.03 10 0.05 62 310 0.48 2.47 0.01 0.17 0.03 10 0.04 63 315 0.47 2.48 0.01 0.17 0.03 10 0.04 64 320 0.47 2.50 0.01 0.17 0.03 10 0.04 65 325 0.46 2.51 0.01 0.16 0.03 10 0.04 66 330 0.46 2.53 0.01 0.16 0.03 10 0.04 67 335 0.45 2.54 0.01 0.16 0.03 10 0.04 68 340 0.45 2.55 0.01 0.16 0.03 9 0.04 69 345 0.45 2.57 0.01 0.16 0.03 9 0.03 70 350 0.44 2.58 0.01 0.16 0,03 9 0.03 71 355 0.44 2.59 0.01 0.15 0.03 9 0.03 72 360 0.43 2.61 0.00 0.00 0.00 0 003 SUM= 1846 cubic feet 0.04 acre-feet Check: V = C*A*P6 V= 0.04 acre-feet OK Hydrograph.xs 51612021 Rational Method Hydrograph Calculations for North County Academy Proposed Hydrology Condition Hydrograph.x!s 5/6/2021 TOTAL AQ =TOTAL Q,1-TOTAL Q TOTAL AQ = 1.33 cfs - 0.38 cfs TOTAL AQ = +0.95 cfs 3.3 Volume Sizing Requirements Design Capture Volume (Per City of Carlsbad BMP Design Manual Worksheet B-2.1): DCV = 399 cf Required Detention Basin Sizing Required 100-year storage = Post-Hydrograph volume - Pre-Hydrograph volume = 1,846 cf— 795 cf 1051 cf required 4 Governs See attached Hydrograph output. Minimum Basin Area (Per Worksheet B-5.1) Min. Footprint = 239 sf Volume Proposed Area = 624 sf Ponding Depth = 6 inch (0.5') Engineered Soil. Layer =24 inch (2.00') Soil Void Ratio = 0.2 Gravel Layers = 24 inch (2.0') Gravel Void Ratio Factor = 0.4 Volume Proposed = (624 sf* 0.5 ft) + (624 sf *2.00 ft * 0.2) + (624 sf* 2.00 ft * 0.4) =312cf+250cf+500cf Volume Proposed = 1062 cf Proposed Volume > Required Volume 3.4 Post-Developed Mitigated 100-Year Hydrograph See attached Hydrograph output. PLSA#3403 . May 2021 Inflow to BMP-1 :1Il / A Link Subct Reach /fond\ 3403 Prepared by Pasco Laret Suiter & Associates Printed 5/7/2021 HydroCAD® 10.10-5a s/n 10097 © 2020 HydroCAD Software Solutions LLC Page 2 Summary for Link IL: Inflow to BMP-1 Inflow = 1.33 cfs @ 4.08 hrs, Volume 0.026 af Primary = 1.33 cfs @ 4.08 hrs, Volume= 0.026 af, Atten= 0%, Lag 0.0 mm Primary outflow = Inflow, Time Span= 0.00-96.00 hrs, dt= 0.01 hrs DISCHARGE Imported from RatHydro adj.csv Link IL: Inflow to BMP-I Hydrograph Inflow 1 0 Primary Time (hours) 3403 Prepared by Pasco Laret Suiter & Associates Printed 5/7/2021 HydroCAD® 10.10-5a s/n 10097 © 2020 HydroCAD Software Solutions LLC Page 3 Summary for Pond 8P: BMP-1 Inflow = 1.33 cfs @ 4.08 hrs, Volume 0.026 at Outflow = 0.29 cfs @ 4.16 hrs, Volume= 0.026 at, Atten= 78%, Lag= 4.7 mm Primary = 0.29 cfs @ 4.16 hrs, Volume= 0.026 at Routing by Dyn-Stor-Ind method, Time Span= 0.00-96.00 hrs, dt= 0.01 hrs Peak Elev= 97.62'@ 4.16 hrs Surf.Area 624 sf Storage 403 cf Plug-Flow detention time= 17.8 min calculated for 0.026 af (100% of inflow) Center-of-Mass det. time= 18.2 mm (248.9 - 230.7) Volume Invert Avail.Storage Storage Description #1 96.00' 1,373 cf Custom Stage Data (Conic) Listed below (Recalc) Elevation Surf .Area Voids lnc.Store Cum.Store Wet.Area (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) (sq-fl) 96.00 624 0.0 0 0 624 98.00 624 40.0 499 499 801 100.00 624 20.0 250 749 978 101.00 624 100.0 624 1,373 1,067 Device Routing Invert Outlet Devices #1 Primary 96.00' 6.0" Round Culvert L= 163.0' RCP, groove end projecting, Ke= 0.200 Inlet/ Outlet Invert= 96.00'/93.73' S=0.0139'/' Cc= 0.900 n= 0.013, Flow Area= 0.20sf #2 Device 1 96.00' 3.0" Vert. Orifice C= 0.600 Limited to weir flow at low heads #3 Device 1 100.50' 12.0" x 12.0" Horiz. Grate C= 0.600 in 12.0" x 12.0" Grate (100% open area) Limited to weir flow at low heads Primary OutFlow Max0.29 cfs @ 4.16 hrs HW97.61' (Free Discharge) t...lCulvert (Passes 0.29 cfs of 0.77 cfs potential flow) f-2=Orifice (Orifice Controls 0.29 cfs 5.88 fps) -3Grate (Controls 0.00 cfs) 3403 Prepared by Pasco Laret Suiter & Associates Printed 5/7/2021 HydroCAD® 10,105a sIn 10097 © 2020 HydroCAD Software Solutions LLC Page 4 Pond 8P: BMP-1 Hydrograph tl Inflow 0 Primary Time (hours) 4.0 HYDRAULIC METHODOLOGY 4.1 AES Pipeflow Onsite storm drain improvements were analyzed using Advanced Engineering Software (AES) Pipeflow which satisfies the County of San Diego design criteria. AES Pipeflow computer program was used to model the 100-year storm event hydraulic grade line within the proposed storm drain system to the proposed biofiltration basin, as well as the mitigated existing 100-year storm even flow within the proposed basin storm drain outlet pipe. Pipeflow computes uniform and non-uniform steady flow water surface profiles and pressure gradients in. circular pipes. Storm drain diameter, Manning's roughness coefficient, discharge are required to complete the hydraulic model. Pipeflow can model supercritical, subcritical and pressure flow, and calculates losses that may occur due to friction., junction structures and other minor loses. See attached Hydraulic output. PLSA #3403 May 2021 PIPE-FLOW HYDRAULICS COMPUTER PROGRAM PACKAGE (Reference: LACFCD,LACRD, AND OCEMA HYDRAULICS CRITERION) (c) Copyright 1982-2016 Advanced Engineering Software (aes) Ver. 23.0 Release Date: 07/01/2016 License ID 1452 Analysis prepared by: PRIVATE SD HYDRAULICS: BASIN INFLOW 1 - HARDSCAPE INLETS FILE NAME: 34031N1.DAT TIME/DATE OF STUDY: 16:14 05/87/2021 GRADUALLY VARIED FLOW ANALYSIS FOR PIPE SYSTEM NODAL POINT STATUS TABLE (Note: "v' indicates nodal point data used.) UPSTREAM RUN DOWNSTREAM RUN NODE MODEL PRESSURE PRESSURE+ FLOW PRESSURE+ NUMBER PROCESS HEAD(FT) MOMENTUM(POUNDS) DEPTH(FT) MOMENTUM(POUNDS) 100.80- 0•57* 10.55 0.43 8.14 } FRICTION 136.80- 074* 11.41 0.43 Dc 8.14 } CATCH BASIN 136.00- 1.01* 9.25 0.43 Dc 2.25 ------------------------------------------------------------------------------ MAXIMUM NUMBER OF ENERGY BALANCES USED IN EACH PROFILE = 25 ------------------------------------------------------------------------------ NOTE: STEADY FLOW HYDRAULIC HEAD-LOSS COMPUTATIONS BASED ON THE MOST CONSERVATIVE FORMULAE FROM THE CURRENT LACRD,LACFCD, AND OCEMA DESIGN MANUALS. JUNCTION ANALYSIS USING FULL INTEGRATION FORMULATION DOWNSTREAM PIPE FLOW CONTROL DATA: NODE NUMBER = 100.00 FLOWLINE ELEVATION = 159.00 PIPE FLOW = 0.74 CFS PIPE DIAMETER = 6.00 INCHES ASSUMED DOWNSTREAM CONTROL HGL = 159.670 FEET ------------------------------------------------------------------------------ NODE 100.00 : HGL = < 159.670>;EGL= < 159.891>;FLOWLINE= < 159.000> FLOW PROCESS FROM NODE 100.00 TO NODE 136.00 IS CODE = 1 UPSTREAM NODE 136.80 ELEVATION = 159.30 (FLOW IS UNDER PRESSURE) ------------------------------------------------------------------------------ CALCULATE FRICTION LOSSES(LACFCD): PIPE FLOW = 0.74 CFS PIPE DIAMETER = 6.00 INCHES PIPE LENGTH = 36.00 FEET MANNING'S N = 0.01000 SF=(Q/K)**2 =(( 0.74)/( 7.294))**2 = 0.01029 HF=L*SF = ( 36.0e)*(0M1029) = 0.371 ------------------------------------------------------------------------------ NODE 136.80 : HGL = < 160.840>;EGL= < 160.261>;FLOWLINE= < 159.300> FLOW PROCESS FROM NODE 180.00 TO NODE 136.08 IS CODE = 8 UPSTREAM NODE 136.00 ELEVATION = 159.30 (FLOW IS UNDER PRESSURE) ------------------------------------------------------------------------------ CALCULATE CATCH BASIN ENTRANCE LOSSES(LACFCD): PIPE FLOW = 0.74 CFS PIPE DIAMETER = 6.00 INCHES FLOW VELOCITY = 3.77 FEET/SEC. VELOCITY HEAD = 0.220 FEET CATCH BASIN ENERGY LOSS = .2*(VELOCITY HEAD) = .2*( 0.220) = 0.044 NODE 136.00 : HGL = < 160.305>;EGL= < 160.305>FLOWLINE= < 159.300> UPSTREAM PIPE FLOW CONTROL DATA: NODE NUMBER = 136.00 FLOWLINE ELEVATION'= 159.30 ASSUMED UPSTREAM CONTROL HGL = 159.73 FOR DOWNSTREAM RUN ANALYSIS END OF GRADUALLY VARIED FLOW ANALYSIS 4' PIPE-FLOW HYDRAULICS COMPUTER PROGRAM PACKAGE (Reference: LACFCD,LACRD, AND OCEMA HYDRAULICS CRITERION) (c) Copyright 1982-2016 Advanced Engineering Software (aes) Ver. 23.0 Release Date: 07/01/2016 License ID 1452 Analysis prepared by: PRIVATE SD HYDRAULICS: BASIN INFLOW 2- ROOF DRAIN LINE FILE NAME: 34031N2.DAT TIME/DATE OF STUDY: 16:12 05/07/2021 GRADUALLY VARIED FLOW ANALYSIS FOR PIPE SYSTEM NODAL POINT STATUS TABLE (Note: "*" indicates nodal point data used.) UPSTREAM RUN DOWNSTREAM RUN NODE MODEL PRESSURE PRESSURE+ FLOW PRESSURE+ NUMBER PROCESS HEAD(FT) MOMENTUM(POUNDS) DEPTH(FT) MOMENTUM(POUNDS) 100.00- 0.50 6.74 0.21* 977 } FRICTION 113.00- 0.40*Dc 6.19 0.40*Dc 6.19 } CATCH BASIN 219.00- -0.41 0.01 0.40*Dc 1.88 MAXIMUM NUMBER OF ENERGY BALANCES USED IN EACH PROFILE = 25 ------------------------------------------------------------------------------ NOTE: STEADY FLOW HYDRAULIC HEAD-LOSS COMPUTATIONS BASED ON THE MOST CONSERVATIVE FORMULAE FROM THE CURRENT LACRD,LACFCD, AND OCEMA DESIGN MANUALS. JUNCTION ANALYSIS USING FULL INTEGRATION FORMULATION DOWNSTREAM PIPE FLOW CONTROL DATA: NODE NUMBER = 100.00 FLOWLINE ELEVATION = 159.00 PIPE FLOW = 8.61 CFS PIPE DIAMETER = 6.00 INCHES ASSUMED DOWNSTREAM CONTROL HGL = 159.500 FEET ------------------------------------------------------------------------------ NODE 100.00 : HGL = < 159.208>;EGL= < 168.180;FLOWLINE= < 159.000> FLOW PROCESS FROM NODE 100.00 TO NODE 113.80 IS CODE = 1 UPSTREAM NODE 113.00 ELEVATION = 160.04 (FLOW IS SUPERCRITICAL) ------------------------------------------------------------------------------ CALCULATE FRICTION LOSSES(LACFCD): PIPE FLOW = 0.61 CFS PIPE DIAMETER = 6.80 INCHES PIPE LENGTH = 13.00 FEET MANNING'S N = 0.01000 NORMAL DEPTH(FT) = 8.19 ------------------------------------------------------------------------------ CRITICAL DEPTH(FT) = 0.40 UPSTREAM CONTROL ASSUMED FLOWDEPTH(FT) = 0.40 GRADUALLY VARIED FLOW PROFILE COMPUTED INFORMATION: DISTANCE FROM FLOW DEPTH ------------------------------------------------------------------------------ VELOCITY SPECIFIC PRESSURE+ CONTROL(FT) (FT) (FT/SEC) ENERGY(FT) MOMENTUM(POUNDS) 0.000 0.397 3.647 0.604 6.19 0.005 0.389 3.724 0.604 6.19 0.023 0.380 3.807 0.605 6.21 0.053 0.372 3.896 0.608 6.23 0.098 0.363 3.990 0.611 6.26 0.159 0.355 4.092 0.615 6.30 0.239 0.346 4.201 0.621 6.35 0.339 0.338 4.317 0.628 6.41 0.464 0.330 4.442 0.636 6.49 0.616 0.321 4.576 0.646 6.58 0.801 0.313 4.720 0.659 6.68 1.023 0.304 4.874 0.673 6.79 1.290 0.296 5.041 8.691 6.92 1.609 0.287 5.220 0.711 7.07 1.993 0.279 5.413 0.734 7.24 2.454 0.271 5.623 8.762 7.43 3.012 0.262 5.849 0.794 7.64 3.693 0.254 6.096 0.831 7.88 4.533 0.245 6.364 0.875 8.15 5.585 0.237 6.656 0.925 8.44 6.933 0.228 6.976 0.985 8.77 8.718 0.220 7.328 1.054 9.15 11.204 0.212 7.715 1.136 9.56 13.000 0.208 7.912 1.180 9.77 NODE 113.00 : HGL = < 160.437>;EGL= < 160.644>;FLOWLINE= < 168.040> FLOW PROCESS FROM NODE 113.00 TO NODE 219.00 IS CODE = 8 UPSTREAM NODE 219.00 ELEVATION = 161.10 (FLOW IS SUBCRITICAL) (NOTE: POSSIBLE JUMP IN OR UPSTREAM OF STRUCTURE) ------------------------------------------------------------------------------ CALCULATE CATCH BASIN ENTRANCE LOSSES(LACFCD): PIPE FLOW = 0.61 CFS PIPE DIAMETER = 6.00 INCHES FLOW VELOCITY = 16.58 FEET/SEC. VELOCITY HEAD = 4.267 FEET CATCH BASIN ENERGY LOSS = .2*(VELOCITY HEAD) = .2*( 4.267) = 8.853 NODE 219.00 : HGL = < 161.497>;EGL= < 161.497>;FLOWLINE= < 161.108> UPSTREAM PIPE FLOW CONTROL DATA: NODE NUMBER = 219.00 FLOWLINE ELEVATION = 161.10 ASSUMED UPSTREAM CONTROL HGL = 161.50 FOR DOWNSTREAM RUN ANALYSIS END OF GRADUALLY VARIED FLOW ANALYSIS 4' PIPE-FLOW HYDRAULICS COMPUTER PROGRAM PACKAGE (Reference: LACFCD,LACRD, AND OCEMA HYDRAULICS CRITERION) (c) Copyright 1982-2016 Advanced Engineering Software (aes) Ver. 23.0 Release Date: 07/01/2016 License ID 1452 Analysis prepared by: PRIVATE SD HYDRAULICS: BASIN OUTFLOW - MITIGATED FLOW FILE NAME: 34030UT.DAT TIME/DATE OF STUDY: 16:04 05/07/2021 GRADUALLY VARIED FLOW ANALYSIS FOR PIPE SYSTEM NODAL POINT STATUS TABLE (Note: "*' indicates nodal point data used.) UPSTREAM RUN DOWNSTREAM RUN NODE MODEL PRESSURE PRESSURE+ FLOW PRESSURE+ NUMBER PROCESS HEAD(FT) MOMENTUM(POUNDS) DEPTH(FT) MOMENTUM(POUNDS) 100.00- 0•50* 3.89 0.18 2.80 } FRICTION 145.00- 0.27*Dc 2.29 0.25*Dc 2.30 } FRICTION 263.00- 0.27*Dc 2.29 0.27*Dc 2.29 ------------------------------------------------------------------------------ MAXIMUM NUMBER OF ENERGY BALANCES USED IN EACH PROFILE = 25 ------------------------------------------------------------------------------ NOTE: STEADY FLOW HYDRAULIC HEAD-LOSS COMPUTATIONS BASED ON THE MOST CONSERVATIVE FORMULAE FROM THE CURRENT LACRD,LACFCD, AND OCEMA DESIGN MANUALS. JUNCTION ANALYSIS USING FULL INTEGRATION FORMULATION DOWNSTREAM PIPE FLOW CONTROL DATA: NODE NUMBER = 100.00 FLOWLINE ELEVATION = 153.40 PIPE FLOW = 0.29 CFS PIPE DIAMETER = 6.00 INCHES ASSUMED DOWNSTREAM CONTROL HGL = 153.900 FEET ------------------------------------------------------------------------------ NODE 100.00 : HGL = < ..i53.900>;EGL= < 153.934>;FLOWLINE= < 153.400> FLOW PROCESS FROM NODE 180.00 TO NODE 145.00 IS CODE = 1 UPSTREAM NODE 145.00 ELEVATION = 154.30 (FLOW SEALS IN REACH) ------------------------------------------------------------------------------ CALCULATE FRICTION LOSSES(LACFCD): PIPE FLOW = 0.29 CFS PIPE DIAMETER = 6.00 INCHES PIPE LENGTH = 45.00 FEET MANNING'S N = 0.01000 NORMAL DEPTH(FT) = 8.18 ------------------------------------------------------------------------------ CRITICAL DEPTH(FT) = 0.27 DOWNSTREAM CONTROL ASSUMED PRESSURE HEAD(FT) = 0.50 GRADUALLY VARIED FLOW PROFILE COMPUTED INFORMATION: DISTANCE FROM FLOW DEPTH ------------------------------------------------------------------------------ VELOCITY SPECIFIC PRESSURE+ CONTROL(FT) (FT) (FT/SEC) ENERGY(FT) MOMENTUM(POUNDS) 0.000 0.500 1.476 0.534 3.89 0.478 0.491 1.483 0.525 3.78 0.940 0.482 1.494 0.516 3.68 1.392 0.473 1.509 0.508 3.58 1.837 0.464 1.526 0.500 3.48 2.274 0.454 1.547 0.492 3.38 2.705 8.445 1.570 0.484 3.29 3.128 0.436 1.595 0.476 3.20 3.545 0.427 1.623 8.468 3.11 3.954 0.418 1.654 0.460 3.03 4.355 0.409 1.687 0.453 2.95 4.747 0.400 1.723 0.446 2.87 5.130 0.391 1.762 0.439 2.80 5.503 0.381 1.804 0.432 2.73 5.865 0.372 1.849 0.425 2.67 6.214 0.363 1.898 0.419 2.61 6.549 0.354 1.958 0.413 2.55 6.867 0.345 2.806 0.408 2.58 7.167 8.336 2.067 0.402 2.45 7.446 0.327 2.133 0.397 2.41 7.699 8.318 2.204 8.393 2.37 7.923 0.308 2.280 8.389 2.34 8.113 0.299 2.363 8.386 2.32 8.261 0.290 2.453 0.384 2.30 8.358 0.281 2.550 8.382 2.29 8.394 0.272 2.656 0.382 2.29 45.008 0.272 2.656 0.382 2.29 NODE 145.80 : HGL = < 154.572>;EGL= < 154.682>;FLOWLINE= < 154.300> FLOW PROCESS FROM NODE 145.00 TO NODE 263.88 IS CODE = 1 UPSTREAM NODE 263.00 ELEVATION = 155.00 (FLOW IS SUPERCRITICAL) ------------------------------------------------------------------------------ CALCULATE FRICTION LOSSES(LACFCD): PIPE FLOW = 0.29 CFS PIPE DIAMETER = 6.00 INCHES PIPE LENGTH = 118.00 FEET MANNING'S N = 0.01000 ------------------------------------------------------------------------------ NORMAL DEPTH(FT) = 0.25 CRITICAL DEPTH(FT) = 8.27 UPSTREAM CONTROL ASSUMED FLOWDEPTH(FT) = 8.27 GRADUALLY VARIED FLOW PROFILE COMPUTED INFORMATION: DISTANCE FROM FLOW DEPTH VELOCITY SPECIFIC PRESSURE+ CONTROL(FT) (FT) (FT/SEC) ENERGY(FT) MOMENTUM(POUNDS) 0.000 0.272 2.656 0.382 2.29 0.003 0.271 2.664 8.382 2.29 0.012 0.271 2.673 0.382 2.29 0.028 0.270 2.681 0.382 2.29 0.052 0.269 2.690 0.382 2.29 0.084 0.269 2.698 0.382 2.29 0.124 8.268 2.787 0.382 2.29 0.175 0.267 2.716 0.382 2.29 0.237 0.266 2.724 0.382 2.29 0.312 0.266 2.733 8.382 2.29 0.401 0.265 2.742 0.382 2.29 0.585 0.264 2.751 0.382 2.29 0.629 0.264 2.760 0.382 2.29 0.774 0.263 2.769 0.382 2.29 0.944 0.262 2.778 0.382 - 2.29 1.144 8.262 2.788 0.382 2.29 1.381 0.261 2.797 0.383 2.29 1.662 0.260 2.886 0.383 2.29 2.001 0.260 2.816 0.383 2.29 2.415 0.259 2.825 0.383 2.29 2.930 0.258 2.835 8.383 2.29 3.594 0.258 2.844 8.383 2.30 4.492 8.257 2.854 0.383 2.30 5.817 0.256 2.864 0.384 2.38 8.190 8.255 2.873 0.384 2.30 118.000 0.255 2.882 0.384 2.30 NODE 263.88 : HGL = < 155.272>;EGL= < 155.382>;FLOWLINE= < 155.000> UPSTREAM PIPE FLOW CONTROL DATA: NODE NUMBER = 263.80 FLOWLINE ELEVATION = 155.00 ASSUMED UPSTREAM CONTROL HGL = 155.27 FOR DOWNSTREAM RUN ANALYSIS END OF GRADUALLY VARIED FLOW ANALYSIS 5.0 ATTACHMENTS PLSA #3403 May 2021 San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 6of26 Table 3-1 RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use I Runoff Coefficient "C" Soil Type NRCS Elements County Elements % IMPER. A B C ID Undisturbed Natural Terrain (Natural) Permanent Open Space 0* 0.20 0.25 0.30 035 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 0.41 045 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 0.52 054 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. Corn) Neighborhood Commercial 80 0.76 0.77 0.78 0.79 Commercial/Industrial (G. Corn) General Commercial 85 0.80 0.80 0.81 0.82 Commercial/industrial (O.P. Corn) 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 1.) General Industrial 95 0.87 (E87 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 36 HYDROLOGIC NODE MAP NORTH COUNTY ACADEMY PRE-DEVELOPMENT MAP LEGEND BASIN BOUNDARY FLOW LINE IMPERVIOUS AREA I I (0 SF) PASCO LARET SUITER ASCATE San Diego I Solana Beach I Orange County Phone 949.661.6695 1 www.plsaengineering.com EX BLDG NODE 1 ELEV. 1634 ---------- ::: MAGNOLIA AVE. SCALE 20 0 20 40 60 HYDROLOGIC NODE MAP NORTH COUNTY ACADEMY POST-DEVELOPMENT MAP NODE 4 IE. 153.4 EX BLDG ==•[ I LEGEND BASIN BOUNDARY SUBAREA BOUNDARY FLOW LINE IMPERVIOUS AREA (8 532 SF) PASCO LARET SUITER & A s s O C D AT F s San Diego I Solana Beach I Orange County Phone 949.661.6695Iwww.plsaengineering.com NODE - ELEV. 161.3 IE, 159.3 MAGNOLIA AVE. SCALE = 20' 0 20 40 60