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CT 2021-0002; GARFIELD BEACH HOMES; FINAL HYDROLOGY STUDY; 2022-09-01
FINAL HYDROLOGY STUDY FOR CARLSBAD TRACT (TENTATIVE MAP) / SITE DEVELOPMENT PERMIT / COASTAL DEVELOPMENT PERMIT 3570 GARFIELD STREET CT 2021-0002 / PUD 2021-0007 / CDP 2021-0038 CITY OF CARLSBAD, CA PREPARED FOR: RINCON CAPITAL 5315 AVENIDA ENCINAS, SUITE 200 CARLSBAD, CA 92008 PH: (888) 357-3553 PREPARED BY: PASCO LARET SUITER & ASSOCIATES, INC. 535 N. HIGHWAY 101, SUITE A SOLANA BEACH, CA 92075 PH: (858) 259-8212 Prepared: July 2021 Revised: February 2022, September 2022 __________________________________________________ TYLER G. LAWSON, RCE 80356 DATE PLSA 3529 TABLE OF CONTENTS SECTION Executive Summary 1.0 Introduction 1.1 Existing Conditions 1.2 Proposed Project 1.3 Conclusions 1.4 References 1.5 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 & Hydraulic Model Output 3.0 Pre-Developed Hydrologic Model Output (100-Year Event) 3.1 Post-Developed Hydrologic Model Output (100-Year Event) 3.2 Pre-Developed vs. Post-Developed Peak Flows (100-Year Event) 3.3 Detention Analysis (100-Year Event) 3.4 Storm Water Pollutant Control 3.5 Appendix 4.0 Appendix A: Hydrology Support Material Appendix B: 100-Year Storm Event Detention Analysis PLSA 3529 Page 1 of 13 1.0 EXECUTIVE SUMMARY 1.1 Introduction This Final Hydrology Study for the proposed development at 3570 Garfield Street 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. 1.2 Existing Conditions The subject property is located on the east side of Garfield Street between Acacia Avenue to the north, and Cherry Ave to the south. The site is adjacent to residential properties directly to the north and south, Garfield Street to the west, and apartment complexes to the east. The existing site consists of mostly natural vegetation with four (4) existing one story buildings and other residential improvements typical to this type of development. Natural vegetation onsite is made up of several trees, low shrubs, and grass. The project site is located within the Agua Hedionda Hydrologic Area, and, more specifically, the Los Monos Hydrologic Sub-Area (904.21) of the Carlsbad watershed. The existing site is comprised of approximately 0.572 acres. Based on a study of the existing topography, the site generally drains from west to east, towards the eastern property line. Currently, there is no existing storm drain infrastructure located onsite to convey drainage, and runoff sheet flows through the site toward the eastern property boundary, discharging across the northeast side of the property. Just offsite on the property to the southeast exists undeveloped land as well as a dirt lot used for vehicle parking and storage directly east. In a rain event, drainage appears to eventually make its way through these areas and ultimately out to Acacia Street to the north. Once in the Acacia Street right- of-way, drainage enters an existing public storm drain curb inlet where it enters the buried pipe network. From here, drainage is routed south to ultimately outlet in the Agua Hedionda Lagoon prior to entering the Pacific Ocean. As such, the subject property can be assumed to have one discharge location from the site in the existing condition. Drainage Basin EX-1 is approximately 0.572 acres in size and 20.8% impervious. Per the Web Soil Survey application available through the United States Department of Agriculture, the area is generally categorized to have group B soils. Based upon soil type B and the amount of existing impervious area onsite, a runoff coefficient of 0.39 was calculated for Basin EX-1 using the methodology described in section 3.1.2 of the San Diego County Hydrology Manual and the formula provided therein. Using the Rational Method Procedure outlined in the San Diego County Hydrology Manual, a peak flow rate and time of concentration was calculated for the drainage basin for the 100-year, 6-hour storm event. Table 1 below summarizes the results of the Rational Method calculations. PLSA 3529 Page 2 of 13 EXISTING DRAINAGE FLOWS DRAINAGE AREA DRAINAGE AREA (ACRES) Q100 (CFS) I100 (IN/HR) EX-1 0.572 1.06 4.76 Table 1. Existing Condition Peak Drainage Flow Rates The peak flow rate for the 100-year, 6-hour storm for Basin EX-1 was determined to be 1.06 cfs with a time of concentration of 8.28 minutes used to calculate rainfall intensity for drainage basin of this size and amount of impervious area; discharging the eastern property line. Refer to pre-development hydrology calculations included in section 3.1 of this report for detailed analysis and the pre-development hydrology map in Appendix A of this hydrology report for existing drainage basin delineation and discharge locations. 1.3 Proposed Project The proposed project includes the clearing of all onsite vegetation and the construction of 12 new multi-family residential condominium structures, consisting of both detached and attached condos with multiple blocks of attached units. The project also proposes various hardscape and landscape improvements including a shared private driveway, rear patios, and pollutant control treatment BMP’s. Site grading along with drainage and utility improvements typical of this type of residential development will also be constructed. Similar to the existing condition, runoff from the proposed development will be directed from west to east to a bioretention basin (INF-2) BMP located along the property. All runoff generated from the proposed roof areas and hardscape will be directed to the biofiltration basin by surface flow along the driveway or private storm drain in the rear yards. Storm water leaving the basin will be routed through the adjacent retaining wall along the eastern property line at multiple outlet locations onto a rip rap dissipator that will spread the runoff and will mimic the existing sheet flow conditions leaving the site. Once discharged from the subject property, runoff will continue downstream through the neighboring properties as it does in the existing condition, ultimately draining to Acacia Street and entering the buried pipe network to continue to the Agua Hedionda Lagoon. The total approximate area of the onsite biofiltration basin is 850 square feet. Similar to the existing condition, the analyzed watershed can be categorized into one major drainage basin with one eventual discharge location from the subject property sheet flowing from the eastern property line. As in the pre-developed condition, Basin PR-1 is 0.572 acres in size, and is approximately 74.4% impervious. Based upon soil type B and the amount of proposed impervious area onsite, a runoff coefficient of 0.73 was calculated for the entire site using the methodology described in section 3.1.2 of the San Diego County Hydrology Manual and the formula provided therein. Using the Rational Method PLSA 3529 Page 3 of 13 Hydrology Manual and the formula provided therein. Using the Rational Method Procedure outlined in the San Diego County Hydrology Manual, a peak flow rate and time of concentration was calculated for the post-development 100-year, 6-hour storm event. Table 2 below summarizes the results of the Rational Method calculations. PROPOSED DRAINAGE FLOWS DRAINAGE AREA DRAINAGE AREA (ACRES) Q100 (CFS) I100 (IN/HR) PR-1 (UNMIT) 0.572 2.61 6.29 PR-1 (MIT) 0.572 1.18 6.59 Table 2. Proposed Condition Peak Drainage Flow Rates The peak flow rate for the 100-year, 6-hour storm for the entire Basin PR-1 was determined to be 2.61 cfs with a time of concentration of 5.37 minutes used to calculate rainfall intensity for drainage basin of this size and amount of impervious area discharging from the site. Once treated and detained in the BMP, runoff that doesn’t infiltrate into the underlying soil will continue east to a flow-spreader system consisting of rock rip rap and an embedded concrete sill running ~20’ along the eastern boundary. This prevents concentrated discharge leaving the site in a concentrated manner and generates an evenly distributed sheet flow condition from the project site to match the existing condition. For an explanation of the mitigated output from the onsite detention please refer to Section 3.3 of this report. In an effort to comply with City of Carlsbad’s storm water standards required of Priority Development projects, the subject property will also implement various source control and site design BMP’s where feasible and applicable in accordance with the City of Carlsbad’s BMP Design Manual. Aside from the proposed biofiltration basin, the site will also implement minimized hardscape areas, minimize soil compaction where applicable, and promote runoff dispersion by draining new hardscape areas through landscaped swales. 1.4 Conclusions Based upon the analysis included in this report, the proposed onsite drainage system design is adequate to capture and convey runoff from the proposed project and discharge via sheet flow methods across the eastern property boundary, as it does in the existing condition, while complying with local and state level water quality regulations. There is no diversion of flows, and water leaving any portion of the site eventually is conveyed through the neighboring land in the same methods that exist currently. The onsite biofiltration basin has been sized to mitigate the peak flows generated in the proposed condition, compared to the pre-project levels, to within 0.12 cfs. It is our professional opinion that this 0.12 cfs increase is negligible and will not adversely impact the downstream condition compared to present day. Once leaving the project site, drainage continues east further downstream PLSA 3529 Page 4 of 13 through the adjacent property to enter the City’s public storm drain system by means of an existing curb inlet located on Acacia Avenue. From here, the buried pipe network conveys storm water to the ultimate outlet location in the Agua Hedionda Lagoon. 1.5 References “San Diego County Hydrology Manual”, revised June 2003, County of San Diego, Department of Public Works, Flood Control Section. “San Diego County Hydraulic Design Manual”, revised September 2014, County of San Diego, Department of Public Works, Flood Control Section “Engineering Standards, Volume 5: Carlsbad BMP Design Manual”, revised February 2016, City of Carlsbad Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil Survey. Available online at http://websoilsurvey.nrcs.usda.gov. PLSA 3529 Page 5 of 13 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 (inches) D = duration (minutes – 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 (in cfs) C = runoff coefficient, ratio of rainfall that produces storm water runoff (runoff vs. infiltration/evaporation/absorption/etc) I = average rainfall intensity for a duration equal to the Tc for the area, in inches per hour. A = drainage area contributing to the basin in acres. The RM equation assumes that the storm event being analyzed delivers precipitation to the entire basin uniformly, and therefore the peak discharge rate will occur when a raindrop 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 PLSA 3529 Page 6 of 13 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. 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 and drainage plans which are outlined in the Grading Ordinance. Please refer to this manual 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. PLSA 3529 Page 7 of 13 3.0 HYDROLOGY MODEL OUTPUT 3.1 Pre-Developed Hydrologic Model Output (100-Year Event) Pre-Development: Q = CIA *Rational Method Equation P100 = 2.5 *100-Year, 6-Hour Rainfall Precipitation Basin EX-1 (Onsite Drainage Basin) Total Area = 24,911 sf 0.572 Acres Impervious Area = 5,187 sf 0.12 Ac Pervious Area = 19,724 sf 0.45 Ac Cn, Weighted Runoff Coefficient, - 0.25, Cn value for natural ground, Type B Soils *Per San Diego Hydrology Design Manual (SDHDM) Section 3.1.2 - 0.90, Cn value for developed/impervious surface *Per SDHDM Section 3.1.2 Cn = 0.9 x 5,187 sf + 0.25 x 19,724 sf = 0.39 24,911 sf Ti = . ∗ . . ∗ √ . % *Per SDCHM Figure 3-3, Initial TC Ti = 7.07 min Tt = Tt1 *Overland flow to eastern PL Tt1 = . . !" . *Per SDCHM Figure 3-4, in hours Tt1 = 0.020 hr * 60 min / 1 hr = 1.21 Min Tc = Ti + Tt1 = 7.07 Min + 1.21 Min = 8.28 Min P6 = 2.5 I = 7.44 x P6 x D-0.645 *Rainfall Intensity Equation I = 7.44 x 2.5 x 8.28-0.645 ≈ 4.76 in/hr I100 ≈ 4.76 in/hr Q100 = C*I*A Q100 = 0.39 x 4.76 in/hr x 0.572 Ac = 1.06 cfs PLSA 3529 Page 8 of 13 3.2 Post-Developed Hydrologic Model Output (100-Year Event) Post-Development (without considering BMP treatment): Q = CIA *Rational Method Equation P100 = 2.5 *100-Year, 6-Hour Rainfall Precipitation Basin PR-1 (Onsite Drainage Basin: Node 1.1-1.6) Total Area = 24,705 sf 0.567 Acres Impervious Area = 18,370 sf 0.422 Acres Pervious Area = 6,335 sf 0.145 Acres Cn, Weighted Runoff Coefficient - 0.25, Cn value for natural ground, Type B soils * Per San Diego Hydrology Design Manual (SDHDM) Section 3.1.2 - 0.9, C value for developed / impervious surface * Per SDHDM Section 3.1.2 Cn = 0.9 x 18,370 sf + 0.25 x 6,335 sf = 0.73 24,705 sf Basin PR-1.1 (Onsite Drainage Basin: Node 1.1-1.4) Total Area = 12,093 sf 0.278 Acres Impervious Area = 8,992 sf 0.206 Acres Pervious Area = 3,101 sf 0.072 Acres Cn, Weighted Runoff Coefficient Cn = 0.73 Ti = . ∗ . .# ∗ √$.$% *Per SDCHM Figure 3-3, Initial TC Ti = 4.06 min Tt = Tt1 *Overland flow to eastern PL Tt1 = . . !" . *Per SDCHM Figure 3-4, in hours Tt1 = 0.022 hr * 60 min / 1 hr = 1.99 Min Tc = Ti + Tt1 = 4.06 Min + 1.31 Min = 5.37 Min PLSA 3529 Page 9 of 13 P6 = 2.5 I = 7.44 x P6 x D-0.645 *Rainfall Intensity Equation I = 7.44 x 2.5 x 5.37-0.645 ≈ 6.29 in/hr I100 ≈ 6.29 in/hr Q100 = C*I*A Q100 = 0.73 x 6.29 in/hr x 0.278 Ac = 1.28 cfs Basin PR-1.2 (Onsite Drainage Basin: Node 1.4) Total Area = 12,612 sf 0.289 Acres Impervious Area = 9,378 sf 0.215 Acres Pervious Area = 3,234 sf 0.074 Acres Cn, Weighted Runoff Coefficient Cn = 0.73 Tc = 5.37 Min P6 = 2.5 I = 7.44 x P6 x D-0.645 *Rainfall Intensity Equation I = 7.44 x 2.5 x 5.37-0.645 ≈ 6.29 in/hr I100 ≈ 6.29 in/hr Q100 = C*I*A Q100 = 0.73 x 6.29 in/hr x 0.289 Ac = 1.32 cfs Basin PR-1 Total QTOT = QPR-1.1 + QPR-1.2 = 2.60 cfs PLSA 3529 Page 10 of 13 Basin PR-1.3 (Onsite Drainage Basin: Node 1.6) Total Area = 206 sf 0.005 Acres Impervious Area = 0 sf 0.000 Acres Pervious Area = 206 sf 0.005 Acres Cn, Weighted Runoff Coefficient - 0.25, Cn value for natural ground, Type B soils * Per San Diego Hydrology Design Manual (SDHDM) Section 3.1.2 - 0.9, C value for developed / impervious surface * Per SDHDM Section 3.1.2 Cn = 0.9 x 0 sf + 0.25 x 206 sf = 0.25 206 sf P6 = 2.5 I = 7.44 x P6 x D-0.645 *Rainfall Intensity Equation I = 7.44 x 2.5 x 5.0-0.645 ≈ 6.29 in/hr I100 ≈ 6.29 in/hr Q100 = C*I*A Q100 = 0.25 x 6.29 in/hr x 0.005 Ac = 0.01 cfs Basin PR-1 Total QTOT = QPR-1.1 + QPR-1.2 + QPR-1.3 = 2.61 cfs 3.3 Pre-Developed vs. Post-Developed Peak Flows (100-Year Event) Total Pre-Development (Discharge Leaving Site) Basin EX-1 Q100 = 1.06 cfs *Discharging from the site at the eastern property boundary Total Post-Development (Discharge Leaving Site) Basin PR-1 Q100 = 2.61 cfs *Discharging from the site at the eastern property boundary Pre-Development vs. Post-Development (Discharge Leaving Site): Pre-Development Post-Development Delta Q100 = 1.06 cfs Q100 = 2.61 cfs 1.55 cfs increase PLSA 3529 Page 11 of 13 *Total overall site runoff increased in proposed condition from pre-development site. Refer to the following section, Section 3.4, of this report for a discussion of detention system proposed to mitigate site to existing conditions. Also refer to the Appendix of this report for existing and proposed condition hydrology node maps showing discharge locations from the subject property. 3.4 Detention Analysis The onsite biofiltration basin provides pollutant control as well as mitigation of the 100- year, 6-hour storm event peak flow rate. At first, the 100-year, 6-hour storm event detention analysis was performed in accordance with Chapter 6 of the San Diego County Hydrology Manual. The results of the analysis provide a static detention requirement by comparing the total volume produced by the 100-year, 6-hour storm in the existing and developed conditions. The total volume can be calculated after producing a hydrograph for each event (pre- and post-developed) with the results of the Rational Method analysis. Calculations and results of this analysis can be shown above in Section 3.3.1 and Section 3.3.2. This method is considered to be conservative, as it does not take into account the routing characteristics of the biofiltration basin. Additionally, a routing analysis will be performed for the proposed biofiltration facility to confirm peak flow will be detained and slowly released to match existing conditions. Civil2d Hydraflow Hydrograph software has the ability to route the 100-year, 6-hour storm event inflow hydrograph (generated and modeled using RatHydro, which is a Rational Method Design Storm Hydrograph software that creates a hydrograph using the results of the Rational Method calculations) through the biofiltration facility. Based on the BMP cross-sectional geometry, stage-storage and outlet structure data, Civil2d Hydraflow Hydrograph has the ability to perform a dynamic / routing analysis and calculate the detained peak flow rate as well as detained time to peak upon leaving the biofiltration BMP. The results of this analysis can be found in Section 4 of the report. PLSA 3529 Page 12 of 13 COMPARISON DRAINAGE FLOWS DRAINAGE AREA DRAINAGE AREA (ACRES) Q100 (CFS) I100 (IN/HR) EX-1 0.572 1.06 4.76 PR-1 (Det) 0.572 1.18 6.59 Table 3. Comparison of Peak Drainage Flow Rates – Detained Condition Table 3 above lists a summary of the results of the detention analysis as compared to the pre-project and post-project unmitigated peak flows. Based on the results of the Civil2d Hydraflow Hydrograph analysis, it was determined that the biofiltration basin facilities provide mitigation for the 100-year, 6-hour storm event peak flow rate by detaining the proposed condition to 1.18 cfs, which is marginally higher than the existing condition Q100 of 1.06 cfs leaving the property to the east via sheet flow methods. It is our professional opinion that this 0.12 cfs increase is negligible and will not adversely impact the downstream condition compared to present day. Furthermore, the continuous runoff model assumed a conservative Tc and the model does not incorporate evapotranspiration, absorption, or nuisance infiltration via vegetated swales, all of which positively impact the runoff flow produced by the proposed design. This method considers conjunctive use of the basin as pollutant control and Q100 detention. Per SD County Hydraulic Manual (6.2.7). For additional information, refer to Appendix A of this Hydrology Report for the pre-and-post-developed project hydrologic node maps. Lastly, refer to Section 4 of this report for the Civil2d Hydraflow Hydrograph detailed output, which shows the dynamic routing of the 100-year, 6-hour storm event through the biofiltration basins and the resulting mitigated peak discharge leaving the subject property. 3.5 Storm Water Pollutant Control To meet the requirements of the MS4 Permit, the biofiltration facility is designed to treat onsite storm water pollutants contained in the volume of runoff from a 24-hour, 85th percentile storm event by slowly infiltrating runoff through an engineered soil layer. Refer to the project Storm Water Quality Management Plan (SWQMP) prepared by Pasco, Laret, Suiter & Associates under separate cover for discussion of pollutant control. PLSA 3529 Page 13 of 13 4.0 APPENDIX IL__·-----_--_I 10.0 9.0 8,0 7.0 6.0 5.0 4.0 3.0 2.0 0.6 0,5 0.4 0.3 0.2 0,1 ' . ' ......... ' ""'I'-,, ' ' ..... 1, ..... ' . ' ...... , .......... ......... ""r-. I""._ I", .... .... "i--.. ...... r-,r-, ,'""' ....... ' ' .... ...... , ""'" ..... .. I' . ' """' --.... ~ .. ' • ""' ~" ' ..... ""'I'-,, "" ,., I', " I", ' ' .......... ! .. --~ ~ "" .... " ' ..... , I= 3.2 in/hr ...... "' " ' ~ ~" -,_ .... .... " ..... ......... I', .... .... " " ' ..... " .. l'o ~ ' ...... 'l'o, "~ ' ...... , I " ' "l'o "~ , ... 'l'o ......... ~" ...... " ,, .. .. "' " " tc = 20 min I I I I 11 I 111 ' 5 6 7 8 9 10 15 20 30 Minutes " .. "" "• " "• " ~ .. .. " ~ .. " " "• " " "· "• " " '" I 40 50 Duration EQUATION I = 7.44 P5 D-0.645 I = Intensity (in/hr) P5 = 6-Hour Precipitation (in) D = Duration (min) 'I',, .... ' ..... '' I'-,, , .... ... , ,, ... ' 1, ""' r-... ' .... ...... .. ~" l'r-..._ , .. ,, "" " 1, "'r-. ...... :--....., .. l'o " :--.I',, ,, " ·~ " ..... ... " .... , ....... :-,... ,., ""' ~ :--., ' .. " ....... " 1, "'"' " ' I'"" 1,._. " :-,...r-... I', :--....., " " 2 3 4 Hours I I 5 6 C)} ± 0 ~ -0 ~ s.o t 5.5 g, 5.0 :, 4.5 '§' 0 4.0 ~ 3.5 !!!.. 3,0 2.5 2.0 1.5 1.0 Intensity-Duration Design Chart -Example Directions for Application: (1) From precipitation maps determine 6 hr and 24 hr amounts for the selected frequency. These maps are included in the County Hydrology Manual (1 O, 50, and 100 yr maps included in the Design and Procedure Manual). (2) Adjust 6 hr precipitation (if necessary) so that it is within the range of 45% to 65% of the 24 hr precipitation (not applicaple to Desert). (3) Plot 6 hr precipitation on the right side of the chart. (4) Draw a line through the point parallel to the plotted lines, (5) This line is the intensity-duration curve for the location being analyzed. Application Form: (a) Selected frequency~ year p (b) P6 = _3_ in., p24 ::;: ~ .~ ::;: ~ %(2) 24 (c) Adjusted p6(2) = _3_ in . (d) Ix= 20 min . {e) J = ~ in./hr. Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. 5-5.5 -6 ~ 1 1.5 r~ 2.5 J-3:-5 -4 4.5' I Ouralion I I I·, I I I I I I I I --5 2.63 3.95 5.27 6.59 7 .90 9.22 10.54 11.86 13.17 14.49 15.81 7 2.124 ~.18 _i.?415.3Q_ 6.36_U£ jl.48-9.54 J 0.60 11.:,6_6_ J.2.72 __ 10 1.68 2.53 3.37 4.21 5.~ 6.74 7.58 8.42 9.27 10.11 --15 1.30 1.95 2.59 3.24 3.89 4.54 5. 19 5.84 6.49 7,13 7.78 --20 1.00 I, .6212.,sfu~ 3.23 3.11 4.31 4.85 5.39 5.93 '5.45 --25 0.93 1 .40 1.87 2.33 2.80 3.27 3.73 4.20 4.67 5. ~ 5.60 --30 0.83 1.24 1.661 2,07 2.49 2,90 3,32 3.73 4.15 4.56 ,..i-98 --. -_-40 0.69-:-1.03 1.38 1.72 2.07 2.41 2.76 3.10 3.45 3.79 4.13 50 o.6_f o.oo T 19-1.49 I 1.19~()~ ..J,39 2.69 2.98 3.28 3.58 60 0.53 0.80 1.06 1.33 1.59 1.86 2,12 2.39 , 2.65 2.9~ 3.18 ~ o::fi 0.61 0.02 1.02 123 1.43 1.63 1.84 2.04 2.25 ~2A5 ----rio 0.34 0.51 0.68 0.85 1.02 1.19 1.36 1.53 1.70 1fil 2.04 7 so 0.29 0.44 0.59 0.7310.88 1.03 1.18.....J.12 1.47 1.62 1.76 180 .9.26 ~r-5g_ 0.65 0.78 0.91 1.Q!J 1.18 1.31 1.44 1.57 240 0.22 0.33 0.43 0.540.651·0.76 0~87 j 0.98 1.08 1.~ 1.30 300 0.19 0.28 0.38 0.470:56 0 .66 0.75 0.85 0.94 1.03 '1:13 --360 0.17 0.25 ·0.33 0.42 0.50 0.58 0.67 I 0.75 0.84 0.92 1.00 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 San Diego County Hydrology Manual Section: 3 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 lot with an area of two or less acres does not have a significant effect where the drainage basin area is 20 to 600 acres. Table 3-2 provides limits of the length (Maximum Length (LM)) of sheet flow to be used in hydrology studies. Initial Ti values based on average C values for the Land Use Element are also included. These values can be used in planning and design applications as described below. Exceptions may be approved by the “Regulating Agency” when submitted with a detailed study. Table 3-2 MAXIMUM OVERLAND FLOW LENGTH (LM) & INITIAL TIME OF CONCENTRATION (Ti) .5% 1% 2% 3% 5% 10% Element* DU/ Acre LM Ti LM Ti LM Ti LM Ti LM Ti LM Ti Natural 50 13.2 70 12.5 85 10.9 100 10.3 100 8.7 100 6.9 LDR 1 50 12.2 70 11.5 85 10.0 100 9.5 100 8.0 100 6.4 LDR 2 50 11.3 70 10.5 85 9.2 100 8.8 100 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 50 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 4.3 100 3.5 HDR 43 50 5.3 65 4.7 75 4.0 85 3.8 95 3.4 100 2.7 N. Com 50 5.3 60 4.5 75 4.0 85 3.8 95 3.4 100 2.7 G. Com 50 4.7 60 4.1 75 3.6 85 3.4 90 2.9 100 2.4 O.P./Com 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2 Limited I. 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2 General I. 50 3.7 60 3.2 70 2.7 80 2.6 90 2.3 100 1.9 *See Table 3-1 for more detailed description 3-12 .6.E Feet 5000 4000 Tc Tc L .6.E = = = = EQUATION (1:;,9~3)°.385 Time of concentration (hours) Watercourse Distance (miles) Change in elevation along effective slope line (See Figure 3-5)(feetJ 3000 2000 400 300 200 30 20 10 5 .6.E SOURCE: California Division of Highways (1941) and Kirpich (1940) L Miles Feet 4000 ' 3000 0.5 ' 2000 300 200 L ' Nomograph for Determination of ' ' Tc Hours Minutes ' ' ' Tc 50 40 30 20 18 16 14 12 10 9 8 7 6 5 4 3 Time of Concentration (Tc) or Travel Time (Tt) for Natural watersheds FIGURE 3-4 Hydrologic Soil Group—San Diego County Area, California Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 3/25/2021 Page 1 of 4 36 6 8 0 8 0 36 6 8 0 9 0 36 6 8 1 0 0 36 6 8 1 1 0 36 6 8 1 2 0 36 6 8 1 3 0 36 6 8 1 4 0 36 6 8 1 5 0 36 6 8 1 6 0 36 6 8 1 7 0 36 6 8 0 8 0 36 6 8 0 9 0 36 6 8 1 0 0 36 6 8 1 1 0 36 6 8 1 2 0 36 6 8 1 3 0 36 6 8 1 4 0 36 6 8 1 5 0 36 6 8 1 6 0 36 6 8 1 7 0 467670 467680 467690 467700 467710 467720 467730 467740 467750 467760 467770 467780 467790 467800 467810 467670 467680 467690 467700 467710 467720 467730 467740 467750 467760 467770 467780 467790 467800 33° 9' 6'' N 11 7 ° 2 0 ' 4 8 ' ' W 33° 9' 6'' N 11 7 ° 2 0 ' 4 2 ' ' W 33° 9' 3'' N 11 7 ° 2 0 ' 4 8 ' ' W 33° 9' 3'' N 11 7 ° 2 0 ' 4 2 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 11N WGS84 0 30 60 120 180Feet 0 5 10 20 30Meters Map Scale: 1:672 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 15, May 27, 2020 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 3/25/2021 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 MlC Marina loamy coarse sand, 2 to 9 percent slopes B 0.8 100.0% Totals for Area of Interest 0.8 100.0% 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. Rating Options Aggregation Method: Dominant Condition Hydrologic Soil Group—San Diego County Area, California Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 3/25/2021 Page 3 of 4USDA = 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 3/25/2021 Page 4 of 4~ TC=BD.84 TC=60.76 l-- li1 ~ Cf) Cl Gj ti: ct: t5 "C=60.85 I I /\ I % I '-- 1 I u. 0 \ ~ m z ~ 18 m- 0 'Tl 0 n 0 0 m I, II ~ 'C=60.861 ~ I I I I Q I \ i I \ \ \ 10"TP / ~ o<c- • o<c-- ASPHAL ASPHAI 0 ( I RF=68.5 o<c-____- __-EXISTING 2 STORY BUILDING o<c- -I- I I " I / I RF=72.9~ t I ----1----- I I I I EXISTING 2 STORY BUILDING o<c-____-APN: ____-204-240-12-00 / I I I / ✓ / / -L..._ J I ( I \ I \ ,,J jJS"TC / / OE OE X 58.5 r -77.4--. :XIS1 ING 5-.-("I -56---____ \ ' ~ \ -------\ \ uv•.DING \ \ ....__ .............. o/.50 ~"':.:;, G 1 STORY BLJ I 1"1: ~..::, \ \ I \[§j V ' \ \ ~ , \,./ / 8"TP < I =,~ v ~':)_~==-~~=.:-=-=-\=o~_:"•-::.1~~ ::::=:J ' " \ )( / 0 j ' c~--f -'7 1-_/'--=-1_ -----\-- -\ I I I I "' c=58.40/ \ \-------.... ,,. 1STORYBU11 s BASIN EX-1 "-I I J I \ ' co~rP\. ' I I ' I 81 I I -I ' •6' " "-:54 / AREA= 24,911 SF "&_ 1 ~-cn_-"""o_.3_9 __ f I I I I I I I I 52.2 / ---~ I I X 536 / I I I I I / I / ) j ( I f 12"1D0 / ) I \ \ \ 16~TD \ ' ~\ I ~ ---~ \ I \: \ '------""' 51.1 \FL= 145' '\ ~ \ \ I k X 50.7 APN: 204-240-13-00 I I I EXISTING 2 STORY BUILDING I RF=67.3 \ t RF·•61.0 ,----1 \ I \ I I I \...-L- "' ---- 16"TD 0 I I Ix _.._j ' ~ I I t I / ( I I \ I ) ----I J ~ I N~DE1.3 V (FG =48.9) ') ----Q100 = 1.06 CFS \ ----'\... \ /~ 49.7 X \ I I I I X \ ~ I J APN: 204-240-14-00 '--~"TD °" ~ ~ X 50.3 X 50., 16"TD 0 ====------====-1:2"TD O 12'ff D -x' \ l i ~--) I ;/,'-~~x•/•;_;x~iiiiiiiiiii~x ••• :=60.82~ I --x \ '-46''TD ______ 16"TD \ r ------CJ' 9 x.;;;+_..X~iiiiiiiil!iX ::J.....__ ~r-.~O~r§~1!§_~"T•D~ -•1 Qillll,~._p"'"--~ "'-,"~· ·,_r, __ \ I ----r==-x-% X-X::>""---X --X XO_) ---------s,..._ X 50.7 A -i.9 X X X X ) 8 TC=60.90 0 m 0 m J:IACTIVE JOBS13529 RINCON GARFIELD snCML IREPORTSIHYDROLOGY\FINALIAPPENDIXl3529-CV-HYDE.Dl'IG \ X APN: \. I -'204-240-1/00 __/~ / / ( ~RF=73.9 \ I ---- ~ \ l I I I < I \ I \ \ I I ( ! \ I \ \ PLAN VIEW -EXISTING HYDROLOGY EXHIBIT SCALE: 1" = 10' HORIZONTAL X X X ----X X X \ \ I \ I I 11 I I \ ( \... I \ ~ -------- I APN: 204-240-0&-00 I ( '----......._ ------- APN: ( 2Q.il-240-22-00 ,r- ~ I LEGEND PROPERTY BOUNDARY CENTERLINE OF ROAD ADJACENT PROPERTY LINE I RIGHT-OF-V'JI\Y -------- 64 EXISTING CONTOUR LINE PROPOSED CONTOUR LINE PROPOSED PA7H OF IRAVEL PROPOSED DIRECTION OF FLOW PROPOSED MAJOR DRAJNAGE BASIN BOUNDARY ---64--- EXISTING IMPERVIOUS AREA BASIN EX-1-AREA CALCULATIONS TOTAL BASIN AREA 24,911 SF (0.57 AC) BASIN EXISTING IMPERVIOUS AREA 5,187 SF (0.12AC) nBASIN EXISTING PERVIOUS PAVEMENT O SF BASIN EXISJJNG PERVIOUSAREA 19,724 SF (0.45AC) % IMPERVIOUS 20.8% Cn 0.39 TIME OF CONCENIRATION 5.37 MINUTES (PER SDCHM) 10 GRAPHIC SCALE 1" = 10' 0 10 20 PRE-DEVELOPMENT HYDROLOGIC NODE MAP 3570 GARFIELD STREET CITY OF CARLSBAD 30 PASCO LAREY SUITER ~ A~~©t!AllE~ San Diego I Solana Beach I Orange County Phone 858.259.8212 I www.plsaengineering.com PLSA 3529-01 \ \ J:IACT/VE JOBS13529 RINCON GARFIELD snCML IREPORTSIHYDROLOGY\FINALIAPPENDIXl3529-CV-HYDD.DWG PLAN VIEW -PROPOSED HYDROLOGY EXHIBIT SCALE: 1" = 10' HORIZONTAL LEGEND PROPERTY BOUNDARY CENTERLINE OF ROAD ADJACENT PROPERTY LINE I -------- _ RIGHT-OF-WAY I I I I I -- EXISTTNG CONTOUR LINE PROPOSED CONTOUR LINE PROPOSED PATH OF TRAVEL PROPOSED DIRECTION OF FLOW PROPOSED MAJOR DRAINAGE BASIN BOUNDARY PROPOSED MINOR DRAINAGE BASIN BOUNDARY EXISTTNG IMPERVIOUSAREA 64 ----64--- l1//2½'.7/27ZVm BASIN PR-1.1-AREA CALCULATIONS BASIN PROPOSED IMPERVIOUSAREA BASIN PROPOSED PERVIOUS AREA 12,093 SF (0.278AC) 8,992 SF (0.206 AC) 3,101 SF (0.072AC) % IMPERVIOUS 74.4% Cn 0.73 TIME OF CONCENTRATION 5.37 MINUTES (PER SDCHM) BASIN PR-1.2 -AREA CALCULATIONS TOTAL BASIN AREA 12,612 SF (0.289AC) 9,378 SF (0.215AC) 3,234 SF (0.074AC) 10 74.4% 0.73 5.37 MINUTES (PER SDCHM) GRAPHIC SCALE 1" = 10' 0 10 20 POST-DEVELOPMENT HYDROLOGIC NODE MAP 3570 GARFIELD STREET CITY OF CARLSBAD 30 PASCO LAREY SUITER ~ A~~©t!AllE~ San Diego I Solana Beach I Orange County Phone 858.259.8212 I www.plsaengineering.com PLSA 3529-01 RATIONAL METHOD HYDROGRAPH PROGRAM COPYRIGHT 1992, 2001 RICK ENGINEERING COMPANY RUN DATE 9/23/2022 HYDROGRAPH FILE NAME Text1 TIME OF CONCENTRATION 5 MIN. 6 HOUR RAINFALL 2.5 INCHES BASIN AREA 0.567 ACRES RUNOFF COEFFICIENT 0.73 PEAK DISCHARGE 2.6 CFS TIME (MIN) = 0 DISCHARGE (CFS) = 0 TIME (MIN) = 5 DISCHARGE (CFS) = 0.1 TIME (MIN) = 10 DISCHARGE (CFS) = 0.1 TIME (MIN) = 15 DISCHARGE (CFS) = 0.1 TIME (MIN) = 20 DISCHARGE (CFS) = 0.1 TIME (MIN) = 25 DISCHARGE (CFS) = 0.1 TIME (MIN) = 30 DISCHARGE (CFS) = 0.1 TIME (MIN) = 35 DISCHARGE (CFS) = 0.1 TIME (MIN) = 40 DISCHARGE (CFS) = 0.1 TIME (MIN) = 45 DISCHARGE (CFS) = 0.1 TIME (MIN) = 50 DISCHARGE (CFS) = 0.1 TIME (MIN) = 55 DISCHARGE (CFS) = 0.1 TIME (MIN) = 60 DISCHARGE (CFS) = 0.1 TIME (MIN) = 65 DISCHARGE (CFS) = 0.1 TIME (MIN) = 70 DISCHARGE (CFS) = 0.1 TIME (MIN) = 75 DISCHARGE (CFS) = 0.1 TIME (MIN) = 80 DISCHARGE (CFS) = 0.1 TIME (MIN) = 85 DISCHARGE (CFS) = 0.1 TIME (MIN) = 90 DISCHARGE (CFS) = 0.1 TIME (MIN) = 95 DISCHARGE (CFS) = 0.1 TIME (MIN) = 100 DISCHARGE (CFS) = 0.1 TIME (MIN) = 105 DISCHARGE (CFS) = 0.1 TIME (MIN) = 110 DISCHARGE (CFS) = 0.1 TIME (MIN) = 115 DISCHARGE (CFS) = 0.1 TIME (MIN) = 120 DISCHARGE (CFS) = 0.1 TIME (MIN) = 125 DISCHARGE (CFS) = 0.1 TIME (MIN) = 130 DISCHARGE (CFS) = 0.1 TIME (MIN) = 135 DISCHARGE (CFS) = 0.1 TIME (MIN) = 140 DISCHARGE (CFS) = 0.1 TIME (MIN) = 145 DISCHARGE (CFS) = 0.1 TIME (MIN) = 150 DISCHARGE (CFS) = 0.1 TIME (MIN) = 155 DISCHARGE (CFS) = 0.1 TIME (MIN) = 160 DISCHARGE (CFS) = 0.1 TIME (MIN) = 165 DISCHARGE (CFS) = 0.1 TIME (MIN) = 170 DISCHARGE (CFS) = 0.1 TIME (MIN) = 175 DISCHARGE (CFS) = 0.1 TIME (MIN) = 180 DISCHARGE (CFS) = 0.1 TIME (MIN) = 185 DISCHARGE (CFS) = 0.2 TIME (MIN) = 190 DISCHARGE (CFS) = 0.2 TIME (MIN) = 195 DISCHARGE (CFS) = 0.2 TIME (MIN) = 200 DISCHARGE (CFS) = 0.2 TIME (MIN) = 205 DISCHARGE (CFS) = 0.2 TIME (MIN) = 210 DISCHARGE (CFS) = 0.2 TIME (MIN) = 215 DISCHARGE (CFS) = 0.2 TIME (MIN) = 220 DISCHARGE (CFS) = 0.3 TIME (MIN) = 225 DISCHARGE (CFS) = 0.3 TIME (MIN) = 230 DISCHARGE (CFS) = 0.4 TIME (MIN) = 235 DISCHARGE (CFS) = 0.5 TIME (MIN) = 240 DISCHARGE (CFS) = 0.9 TIME (MIN) = 245 DISCHARGE (CFS) = 2.6 TIME (MIN) = 250 DISCHARGE (CFS) = 0.4 TIME (MIN) = 255 DISCHARGE (CFS) = 0.3 TIME (MIN) = 260 DISCHARGE (CFS) = 0.2 TIME (MIN) = 265 DISCHARGE (CFS) = 0.2 TIME (MIN) = 270 DISCHARGE (CFS) = 0.2 TIME (MIN) = 275 DISCHARGE (CFS) = 0.1 TIME (MIN) = 280 DISCHARGE (CFS) = 0.1 TIME (MIN) = 285 DISCHARGE (CFS) = 0.1 TIME (MIN) = 290 DISCHARGE (CFS) = 0.1 TIME (MIN) = 295 DISCHARGE (CFS) = 0.1 TIME (MIN) = 300 DISCHARGE (CFS) = 0.1 TIME (MIN) = 305 DISCHARGE (CFS) = 0.1 TIME (MIN) = 310 DISCHARGE (CFS) = 0.1 TIME (MIN) = 315 DISCHARGE (CFS) = 0.1 TIME (MIN) = 320 DISCHARGE (CFS) = 0.1 TIME (MIN) = 325 DISCHARGE (CFS) = 0.1 TIME (MIN) = 330 DISCHARGE (CFS) = 0.1 TIME (MIN) = 335 DISCHARGE (CFS) = 0.1 TIME (MIN) = 340 DISCHARGE (CFS) = 0.1 TIME (MIN) = 345 DISCHARGE (CFS) = 0.1 TIME (MIN) = 350 DISCHARGE (CFS) = 0.1 TIME (MIN) = 355 DISCHARGE (CFS) = 0.1 TIME (MIN) = 360 DISCHARGE (CFS) = 0.1 TIME (MIN) = 365 DISCHARGE (CFS) = 0 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022 Friday, 09 / 23 / 2022 Hyd. No. 1 <no description> Hydrograph type = Manual Peak discharge = 2.600 cfs Storm frequency = 100 yrs Time to peak = 4.08 hrs Time interval = 5 min Hyd. volume = 3,930 cuft 2 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (hrs) <no description> Hyd. No. 1 -- 100 Year Hyd No. 1 - - )_ r' - -I , \ Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022 Friday, 09 / 23 / 2022 Hyd. No. 2 <no description> Hydrograph type = Reservoir Peak discharge = 1.176 cfs Storm frequency = 100 yrs Time to peak = 4.17 hrs Time interval = 5 min Hyd. volume = 3,160 cuft Inflow hyd. No. = 1 - <no description> Max. Elevation = 53.90 ft Reservoir name = BMP Basin Max. Storage = 556 cuft Storage Indication method used. Exfiltration extracted from Outflow. 3 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (hrs) <no description> Hyd. No. 2 -- 100 Year Hyd No. 2 Hyd No. 1 Total storage used = 556 cuft ~I , - .. ., J ~- f!JII' 111111111 Pond Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022 Friday, 09 / 23 / 2022 Pond No. 1 - BMP Basin Pond Data Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 53.25 ft Stage / Storage Table Stage (ft)Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 53.25 850 0 0 0.25 53.50 850 213 213 0.50 53.75 850 213 425 0.75 54.00 850 213 638 1.00 54.25 850 213 850 1.25 54.50 850 213 1,063 Culvert / Orifice Structures Weir Structures [A] [B] [C] [PrfRsr][A] [B] [C] [D] Rise (in)= 8.00 3.00 1.00 0.00 Span (in)= 8.00 15.00 4.00 0.00 No. Barrels = 1 1 1 0 Invert El. (ft)= 50.00 53.25 53.50 0.00 Length (ft)= 20.00 0.00 0.00 0.00 Slope (%)= 1.00 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a No No No Crest Len (ft)= 6.00 0.00 0.00 0.00 Crest El. (ft)= 53.92 0.00 0.00 0.00 Weir Coeff.= 3.33 3.33 3.33 3.33 Weir Type = Rect --- --- --- Multi-Stage = Yes No No No Exfil.(in/hr)= 5.000 (by Contour) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). 0.00 1.00 2.00 3.00 4.00 5.00 6.00 Stage (ft) 0.00 53.25 0.20 53.45 0.40 53.65 0.60 53.85 0.80 54.05 1.00 54.25 1.20 54.45 1.40 54.65 1.60 54.85 1.80 55.05 2.00 55.25 Elev (ft) Discharge (cfs) Stage / Discharge Total Q ~ ~ V - ~ ~v / / 24-in Grated Inlet in Sag (Assumed 50% Clogging) Cw 3 Unitless L 2 ft Pe 4.00 ft W 2 ft C0 0.67 Unitless Ae 2 *Pe assumes 50% clogging Weir Orifice Q (cfs) d (ft) d (in)Q (cfs) d (ft) 0.00 0.083 1 5.38 0.25 0.03 0.167 2 7.60 0.5 0.09 0.250 3 9.31 0.75 0.222222 0.333 4 10.75 1 0.43 0.417 5 12.02 1.25 0.75 0.500 6 13.17 1.5 1.19 0.583 7 1.78 0.667 8 2.53 0.750 9 Step 1. Calculate the capacity of a grate inlet operating as a weir, using the weir equation (Equation 2-16) with a length equiYalent to perimeter of the grate. When the grate is located next to a curb, disregard the length of the grate against the curb. 0= C Pd312 ~ We (2-16) where ... Q = Cw = Pe = d = inlet capacity of the grated inlet (ft3/s); weir coefficient (Cw=3.0 for U.S. Traditional Units); effective grate perimeter length (ft); and flow depth approaching inlet (ft). To account for the effects of clogging of a grated inlet operating as a weir, a clogging factor of fifty percent (Cr=0.50) shall be applied to the actual (unclogged) perimeter of the grate (P): Step 2. where ... Q Co g Calculate the capacity of a grate inlet operating as an orifice. U se the orifice equation (Equatio n 2-18), assuming the clear opening of the grate reduced by a clogging factor CA=0.50 (Equation 2-19). A San Diego Regional Standard No. D-15 grate has an actual clear opening of A=4.1 ft2. The Federal Highway Administration's Urban Drainage D esign Manual (HEC-22) provides guidance for other grate types and configurations. inlet capacity of the grated inlet (ft3/s); orifice coefficient (C0 =0.67 for U.S. T raditional Units); gravitational acceleration (ft/s2); (2-18) (2-19) d = A e flow depth above inlet (ft); effective (clogged) grate area (ft2); CA = A area clogging factor (CA=0.50); and actual opening area of the grate inlet (i.e., the total area less the area of bars or vanes). The actual opening area for a San Diego Regional Standard No. D-15 grate is A=4 .7 ft2. The Federal Highway Administration's Urban Drainage D esign Manual (HEC-22) provides guidance for other grate types and co nfigurations. 36-in Grated Inlet in Sag (Assumed 50% Clogging) Cw 3 Unitless L 3 ft Pe 6.00 ft W 3 ft C0 0.67 Unitless Ae 4.5 *Pe assumes 50% clogging Weir Orifice Q (cfs) d (ft) d (in)Q (cfs) d (ft) 0.01 0.0833 1 12.10 0.25 0.04 0.167 2 17.11 0.5 0.14 0.250 3 20.95 0.75 0.333 0.333 4 24.20 1 0.65 0.417 5 27.05 1.25 1.13 0.500 6 29.63 1.5 1.79 0.583 7 2.67 0.667 8 3.80 0.750 9 Step 1. Calculate the capacity of a grate inlet operating as a weir, using the weir equation (Equation 2-16) with a length equiYalent to perimeter of the grate. When the grate is located next to a curb, disregard the length of the grate against the curb. 0= C Pd312 ~ We (2-16) where ... Q = Cw = Pe = d = inlet capacity of the grated inlet (ft3/s); weir coefficient (Cw=3.0 for U.S. Traditional Units); effective grate perimeter length (ft); and flow depth approaching inlet (ft). To account for the effects of clogging of a grated inlet operating as a weir, a clogging factor of fifty percent (Cr=0.50) shall be applied to the actual (unclogged) perimeter of the grate (P): Step 2. where ... Q Co g Calculate the capacity of a grate inlet operating as an orifice. Use the orifice equation (Equation 2-1 8), assuming the clear opening of the grate reduced by a clogging factor CA=0.50 (Equation 2-19). A San Diego Regional Standard No. D-1 5 grate has an actual clear opening of A=4.7 tt2. The Federal Highway Administration's Urban Drainage Design Manual (H EC-22) provides guidance for other grate types and configurations. inlet capacity of the grated inlet (ft3/s); orifice coefficient (C0 =0.67 for U.S. Traditional Units); gravitational acceleration (ft/s2); (2-18) (2-19) d = A e flow depth above inlet (ft); effective (clogged) grate area (ft2); CA A area clogging factor (CA=0.50); and actual opening area of the grate inlet (i.e., the total area less the area of bars or vanes). The actual opening area for a San Diego Regional Standard No. D-l5 grate is A=4.7 ft2. The Federal Highway Administration's Urban Drainage Design Manual (HEC-22) provides guidance for other grate types and configurations. Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.Monday, Sep 26 2022 18-in PVC Storm Drain Pipe Circular Diameter (ft)= 1.50 Invert Elev (ft) = 100.00 Slope (%)= 7.70 N-Value = 0.130 Calculations Compute by:Known Depth Known Depth (ft) = 1.00 Highlighted Depth (ft)= 1.00 Q (cfs)= 2.294 Area (sqft)= 1.26 Velocity (ft/s)= 1.83 Wetted Perim (ft) = 2.87 Crit Depth, Yc (ft) = 0.58 Top Width (ft)= 1.41 EGL (ft)= 1.05 0 1 2 3 Elev (ft)Section 99.50 100.00 100.50 101.00 101.50 102.00 Reach (ft) ~ ............ ~ 7 f ~ V \ , -' - -\ ' \ I \. / ~ / -~ ~ ---V"