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Boylan Shores SWMP
STORMWATER MANAGEMENT PLAN Boylan Shores Chanhassen, MN DATE:10-17-2019 REVISED:5-22-2020 CMIPROJECT NO.:0515 PREPARED FOR: Campion Engineering Services, Inc. 1800 Pioneer Creek Center Maple Plain, MN 55359 PREPARED BY: Civil Methods, Inc. 1551 Livingston Avenue, Ste. 104 West St. Paul, MN 55118 ENGINEER CERTIFICATION: I hereby certify that this plan, specification, or report was prepared by me or under my direct supervision and that I am a duly licensed Professional Engineer under the laws of the State of Minnesota. Name:David Poggi, PE Signed: Date:05-22-2020 Registration: MN No. 44573 Boylan Shores – SWMP May 2020 Civil Methods, Inc.Page | i No. 0515 Table of Contents 1. INTRODUCTION ............................................................................................................................................. 1 2. EXISTING SITE CONDITION ............................................................................................................................. 1 3. PROPOSED SITE CONDITION .......................................................................................................................... 1 3.1 DRAINAGE PATTERNS .................................................................................................................................. 1 3.2 VOLUME CONTROL AND WATER QUALITY......................................................................................................... 2 3.3 RATE CONTROL .......................................................................................................................................... 3 APPENDIX A – SOILS INFORMATION APPENDIX B – DRAINAGE DIAGRAM APPENDIX C – P8 OUTPUT APPENDIX D – HYDROCAD OUTPUT APPENDIX E – DOWNSTREAM SEWER (MINNEWASHTA PKWY) DESIGN REVIEW Boylan Shores – SWMP May 2020 Civil Methods, Inc.Page | 1 No. 0515 1. INTRODUCTION The Boylan Shores development is proposed to be located between Country Oaks Drive and Minnewashta Parkway in Chanhassen, MN. Construction of the three new homes and associated hard surfaces will include 19,270 ft2 of new or reconstructed impervious area on the property. The development must meet the permanent stormwater management standards of the City of Chanhassen and the Minnehaha Creek Watershed District (MCWD). Regulatory Stormwater Requirements: 1) Infiltrate or otherwise retain the volume of 1.1” (City more restrictive) of rainfall over all site impervious area. 2) Treat the runoff to the following pollutant reductions: 90% TSS & 60% TP. 3) Match or reduce stormwater discharge rates for the 1-, 2-, 10-, and 100-year, Atlas-14 storm events. 4) Maintain a minimum of 3.0’ of separation from the bottom of an infiltration device to the groundwater table elevation. 5) When infiltration not feasible due to site restrictions, alternative methods must be evaluated. When biofiltration is used, volume shall be increased by a factor of 2 (MCWD). 2. EXISTING SITE CONDITION The existing 2.41 acre residential parcel consists includes a residence, drive and wooded / grass areas, with soils consisting primarily of silty clays. The soils have very poor infiltration capacity and generally fall within the HSG Type D category (Appendix A). Stormwater runoff from the site drains primarily to the south onto the adjacent private property, though a small portion at the east end drains directly to Minnewashta Parkway. All drainage from the property ultimately drains to the east (Appendix B). 3. PROPOSED SITE CONDITION 3.1 DRAINAGE PATTERNS The proposed site condition includes 19,270 ft2 (0.44 ac) of impervious area associated with the three residential lots and private drive. The property drainage patterns will be modified to direct as much runoff as possible to a new stormwater management basin and away from Boylan Shores – SWMP May 2020 Civil Methods, Inc.Page | 2 No. 0515 the adjacent private property. The basin outlet will be connected to the existing sewer under Minnewashta Parkway. Proposed drainage patterns are illustrated on Figure 1 (Appendix B). 3.2 VOLUME CONTROL AND WATER QUALITY The proposed biofiltration basin will provide a sufficient level of retention to meet the volume control requirements outlined above, including filtering a volume equal to 2.0” of runoff over all impervious area. Since biofiltration is given 50% credit per the MCWD Rule, 2.0” is used instead of 1.0” for basin sizing. The relevant volume calculations are as follows: Biofiltration Volume Calculation: 1” x Impervious Area x 2 = 1” x (1’/12”) x 19,270 ft2 x 2 = 3,212 ft3 Total Volume Required = 3,212 ft3 Total Volume Provided = 4,617 ft3 As indicated, the biofiltration volume provided (4,617 cu. ft.) exceeds the volume of runoff required to be retained on-site. The provided biofiltration volume is calculated as the volume stored in the basin between the bottom elevation (967.5) and the outlet elevation (969.5), with no credit assumed for filtration occurring during rainfall. The basin bottom will consist of 18” of sandy topsoil borrow (Mn/DOT Rooting Topsoil Borrow), with a 6” underdrain encased in washed rock. The basin shall draw down within 48 hours infiltrating at a rate of 0.8” per hour (a conservative estimate of the engineered media) the maximum permissible basin depth of stored volume is 3.2 ft; however, the proposed basin is limited to 2.0 ft to ensure drawdown. Treatment is required to reduce discharge of sediment (TSS) by 90% and phosphorus (TP) by 60%. While it is not feasible to convey runoff from the entire property to the basin (namely, back yards of the easterly lots), the basin has been oversized to allow for extra treatment. The reductions have been quantified using an acceptable computer model (P8, in this case), as required. To meet MCWD standards, the oversized basin must provide treatment equivalent to a standard basin sized to treat the entire site impervious area. For verification purposes, a “baseline” scenario has been modeled to establish the pollutant load reduction associated with the minimum design specs. This baseline scenario is identified as such in the P8 model, and includes the total impervious area as the watershed, while the related BMP includes a volume equivalent to 2” over that area. The pollutant removal load associated with this Boylan Shores – SWMP May 2020 Civil Methods, Inc.Page | 3 No. 0515 scenario has been matched with the remaining proposed condition (within model error), as summarized in the following table: Baseline Removal Pollutant Biofiltration (lb/yr) Biofiltration (lb/yr) Swale 2 (lb/yr) Swale 2.1 (lb/yr) Swale 3 (lb/yr) Total (lb/yr) TSS 303.09 260.61 24.79 2.69 13.93 302.02 TP 0.95 0.82 0.06 0.02 0.04 0.94 Proposed Removal The Baseline BMP design is so large (sized for 2” volume) that it effectively removes all pollutants in a modeled annual simulation. Therefore, it is extremely difficult to “oversize” to make up for areas directly discharging offsite in the proposed condition, particularly on small sites such as this. However, utilizing swale BMPs in P8 to reflect the swales receiving rooftop runoff, the removal is matched (within model error). 3.3 RATE CONTROL The configuration and outlet works associated with the proposed basin will control the stormwater discharge rate from the majority of the project site, while the remaining area will drain overland to the south. The existing and proposed site conditions have been modeled with the HydroCAD modeling software using the TR-20 methodology and Atlas 14 rainfall amounts (Appendix D). The basin outlet control structure will include a skimming manhole with a weir wall orifice and 12” outlet pipe discharging to the City sewer, as shown in the modeling and project plans. As designed, the basin will mitigate the increased runoff flow rates associated with the new construction. Model results are summarized in Table 1: Table 1: Flow Rate Comparison Node, ID Existing (cfs) Proposed (cfs)Existing (cfs) Proposed (cfs)Existing (cfs) Proposed (cfs)Existing (cfs) Proposed (cfs) 1R - South 1.3 0.2 1.7 0.3 3.9 0.5 8.9 1.0 2R - Parkway 0.7 0.7 0.8 0.9 1.6 1.7 3.2 4.2 3R - Total 1.8 0.9 2.3 1.1 5.1 2.2 11.4 5.1 1-Year, 2.49"2-Year, 2.75"10-Year, 4.23"100-Year, 7.25" As indicated, the total site discharge for the design events is reduced by over half; however, due to redirection of the majority of the flow from the private property towards the Parkway, there is a marginal increase in flowrate to the street. Due to this increase, the sewer system in Minnewashta Parkway has been evaluated to ensure adequate capacity exists for the increased flow. Boylan Shores – SWMP May 2020 Civil Methods, Inc.Page | 4 No. 0515 According to as-built information provided by the City, the existing pipe leaving the connection structure is a 12” RCP pipe at 1.27% (Record Drawing 90-15-24ss and 90-15-25ss) with a Manning capacity of 4.0 cfs. As indicated in the HydroCAD results, the existing and proposed 10-yr discharge from the site to the street is 1.6 cfs and 1.7 cfs, respectively. The two catch basins in the road receive an additional 1.5 cfs from the 0.44 ac subcatchment area (Appendix E), yielding a total flow rate of 3.1 cfs to the 12” pipe in the existing condition and 3.2 cfs in the proposed. Both are under the 4.0 cfs capacity of the 12” line. Appendix A – Soils Information Appendix B – Drainage Diagram LAKE MINNEWASHTACOUNTRY OAKS DRIVEMINNEWASHTA PARKWAY1P 3 2 1 1R 2R LAKE MINNEWASHTACOUNTRY OAKS DRIVEMINNEWASHTA PARKWAY2 1 2R 1R CIVIL METHODS, INC. 1551 Livingston Avenue, Suite 104 West St. Paul, MN 55118 o:763.210.5713 | www.civilmethods.com CHANHASSEN, MN FIG1 OWNER:TITLE:SHEET NO:5/15/2020 3:33 PMPrint Date:File Loc:C:\CM\Civil Methods, Inc\CMI - Documents\7. Projects\0515_CES Lake Minnewashta Property SWM\08_DRAWINGS AND SPECIFICATIONS\C3D\Sheets\0515_WR.dwgCHANHASSEN, MN BOYLAN SHORES X X X SUBCATCHMENT NODE ID BASIN NODE ID REACH NODE ID SUBCATCHMENT DELINEATION DRAINAGE DIRECTION LEGEND: BIOFILTER VOL = 3600 CF (MIN) BOT = 967.5 OUT = 969.5 HWL = 971.3 DT EL = 965.5 Appendix C – P8 Output P8 Urban Catchment Model, Version 3.5 Run Date 05/22/20 Case 200522_Laketown Homes_baseline.p8c FirstDate 10/02/78 Precip(in)29.5 Title Laketown Homes, Chanhassen LastDate 09/30/79 Rain(in)23.72 PrecFile msp_4989.pcp Events 65 Snow(in)5.79 PartFile nurp50.p8p TotalHrs 8690 TotalYrs 0.99 Case Title Laketown Homes, Chanhassen Case Data File 200522_Laketown Homes_baseline.p8c Path C:\CM\Civil Methods, Inc\CMI - Documents\7. Projects\0515_CES Lake Minnewashta Property SWM\06_MODELING AND ANALYSIS\P8\ Case Notes: Storm Data File msp_4989.pcp Particle File nurp50.p8p Air Temp File File msp_4889.tem Time Steps Per Hour 4 Minimum Inter-Event Time (hrs)10 Maximum Continuity Error %2 Rainfall Breakpoint (inches)0.8 Precipitation Scale Factor 1 Air Temp Offset (deg-F)0 Loops Thru Storm File 1 Simulation Dates Start 10/1/1978 Keep 1/1/9999 Stop 9/30/1979 Max Snowfall Temperature (deg-f)32.0 SnowMelt Temperature (deg-f)32.0 Snowmelt Coef (in/degF-Day)0.06 Soil Freeze Temp (deg-F)32.0 Snowmelt Abstraction Factor 1.00 Evapo-Trans. Calibration Factor 1.00 Growing Season Start Month 5 Growing Season End Month 10 5-Day Antecedent Rainfall + Runoff (inches) CN Antecedent Moisture Condition AMC-II AMC-III Growing Season 1.40 2.10 NonGrowing Season 0.50 1.10 Biofilter Watershed Data Watershed Name 1 Baseline Watershed 2 3 Runoff to Device Biofilter 1 Baseline BMP Grass Swale2 Grass Swale3 Infiltration to Device Watershed Area 0.38 0.442 0.041 0.021 SCS Curve Number (Pervious)80 80 80 80 Scale Factor for Pervious Runoff Load 1 1 1 1 Indirectly Connected Imperv Fraction 0 0 0 0 UnSwept Impervious Fraction 1 1 1 1 UnSwept Depression Storage (inches)0.02 0.02 0.02 0.02 UnSwept Imperv. Runoff Coefficient 1 1 1 1 UnSwept Scale Factor for Particle Loads 1 1 1 1 Swept Impervious Fraction 0 0 0 0 Swept Depression Storage (inches)0.02 0.02 0.02 0.02 Swept Imperv. Runoff Coefficient 1 1 1 1 Swept Scale Factor for Particle Loads 1 1 1 1 Sweeping Frequency 0.5 0.5 0.5 0.5 Sweeping Efficiency 1 1 1 1 Sweeping Start Date (MMDD)101 101 101 101 Sweeping Stop Date (MMDD)1231 1231 1231 1231 Device Data Device Name Biofilter 1 Baseline BMP Grass Swale2 Grass Swale2.1 Grass Swale3 Device Type INF_BASIN INF_BASIN SWALE SWALE SWALE Infiltration Outlet Normal Outlet Grass Swale2.1 Spillway Outlet Grass Swale2.1 Particle Removal Scale Factor 1 1 1 1 1 Bottom Elevation (ft)967.5 967.5 972 971 972 Bottom Area (acres)0.031 0.0369 Permanent Pool Area (acres) Permanent Pool Volume (ac-ft) Perm Pool Infilt Rate (in/hr) Flood Pool Area (acres)0.075 0.0369 Flood Pool Volume (ac-ft)0.106 0.0737 Flood Pool Infilt Rate (in/hr)0.8 0.8 0.45 0.45 0.45 Infilt Basin Void Fraction (%)100 100 Detention Pond Outlet Parameters Outlet Type Outlet Orifice Diameter (in) Orifice Discharge Coef Outlet Weir Length (ft) Weir Discharge Coef Perforated Riser Height (ft) Number of Holes in Riser Holes Diameter Flood Pool Drain Time (hrs) Swale Parameters Length of Flow Path (ft)60 120 120 Slope of Flow Path %2 1 2 Bottom Width (ft)8 8 10 Side Slope (ft-v/ft-h)10 10 10 Maximum Depth of Flow (ft)0.5 0.5 0.5 Mannings n Constant 0.15 0.15 0.15 Hydraulic Model 0 0 0 Pipe, Splitter, Aquifer Parameter Hydraulic Res. Time (hrs) Particle Data Particle File nurp50.p8p Particle Class P0%P10%P30%P50%P80% Filtration Efficiency (%)90 100 100 100 100 Settling Velocity (ft/hr)0 0.03 0.3 1.5 15 First Order Decay Rate (1/day)0 0 0 0 0 2nd Order Decay (1/day-ppm)0 0 0 0 0 Impervious Runoff Conc (ppm)1 0 0 0 0 Pervious Runoff Conc (ppm)1 100 100 100 200 Pervious Conc Exponent 0 1 1 1 1 Accum. Rate (lbs-ac-day)0 1.75 1.75 1.75 3.5 Particle Removal Rate (1/day)0 0.25 0.25 0.25 0.25 Washoff Coefficient 0 20 20 20 20 Washoff Exponent 0 2 2 2 2 Sweeper Efficiency 0 0 0 5 15 Water Quality Component Data Component Name TSS TP TKN CU PB ZN Water Quality Criteria (ppm) Level 1 5 0.025 2 2 0.02 5 Level 2 10 0.05 1 0.0048 0.014 0.0362 Level 3 20 0.1 0.5 0.02 0.15 0.38 Content Scale Factor 1 1 1 1 1 1 Particle Composition (mg/kg) P0%0 99000 600000 13600 2000 64000 P10%1000000 3850 15000 340 180 1600 P30%1000000 3850 15000 340 180 1600 P50%1000000 3850 15000 340 180 1600 P80%1000000 0 0 340 180 0 P8 Urban Catchment Model, Version 3.5 Run Date 05/22/20 Case 200522_Laketown Homes_baseline.p8cFirstDate 10/02/78 Precip(in)29.5 Title Laketown Homes, Chanhassen LastDate 09/30/79 Rain(in)23.72 PrecFile msp_4989.pcp Events 65 Snow(in)5.79 PartFile nurp50.p8p TotalHrs 8690 TotalYrs 0.99 Mass Balances by Device Device: OVERALL Type:NONE Flow Loads(lbs)Concentrations (ppm) Mass Balance Term acre-ft TSS TP TSS TP 01 watershed inflows 2.08 606.86 1.96 107.21 0.35 03 infiltrate 2.03 101.46 0.93 18.35 0.17 04 exfiltrate 2.03 0.00 0.05 0.01 05 filtered 0.00 101.46 0.88 0.00 0.00 06 normal outlet 0.05 0.96 0.02 7.20 0.13 08 sedimen + decay 0.00 503.54 1.01 0.00 0.00 09 total inflow 2.08 606.86 1.96 107.21 0.35 10 surface outflow 0.05 0.96 0.02 7.20 0.13 11 groundw outflow 2.03 0.00 0.05 0.01 12 total outflow 2.08 0.96 0.07 0.17 0.01 13 total trapped 0.00 605.00 1.89 14 storage increase 0.00 0.00 0.00 15 mass balance check 0.00 0.89 0.00 Load Reduction (%)0.00 99.69 96.16 Device: Baseline BMP Type:INF_BASIN Flow Loads(lbs)Concentrations (ppm) Mass Balance Term acre-ft TSS TP TSS TP 01 watershed inflows 1.04 303.43 0.98 107.21 0.35 03 infiltrate 1.04 53.16 0.48 18.78 0.17 04 exfiltrate 1.04 0.00 0.03 0.01 05 filtered 0.00 53.16 0.45 0.00 0.00 08 sedimen + decay 0.00 249.93 0.50 0.00 0.00 09 total inflow 1.04 303.43 0.98 107.21 0.35 11 groundw outflow 1.04 0.00 0.03 0.01 12 total outflow 1.04 0.00 0.03 0.01 13 total trapped 0.00 303.09 0.95 14 storage increase 0.00 0.00 0.00 15 mass balance check 0.00 0.34 0.00 Load Reduction (%)0.00 99.89 97.00 Device: Biofilter 1 Type:INF_BASIN Flow Loads(lbs)Concentrations (ppm) Mass Balance Term acre-ft TSS TP TSS TP 01 watershed inflows 0.90 260.87 0.84 107.21 0.35 03 infiltrate 0.90 45.72 0.42 18.79 0.17 04 exfiltrate 0.90 0.00 0.02 0.01 05 filtered 0.00 45.72 0.39 0.00 0.00 08 sedimen + decay 0.00 214.88 0.43 0.00 0.00 09 total inflow 0.90 260.87 0.84 107.21 0.35 11 groundw outflow 0.90 0.00 0.02 0.01 12 total outflow 0.90 0.00 0.02 0.01 13 total trapped 0.00 260.61 0.82 14 storage increase 0.00 0.00 0.00 15 mass balance check 0.00 0.26 0.00 Load Reduction (%)0.00 99.90 97.02 Device: Grass Swale2 Type:SWALE Flow Loads(lbs)Concentrations (ppm) Mass Balance Term acre-ft TSS TP TSS TP 01 watershed inflows 0.10 28.15 0.09 107.21 0.35 03 infiltrate 0.03 1.44 0.01 16.85 0.16 04 exfiltrate 0.03 0.00 0.00 0.01 05 filtered 0.00 1.44 0.01 0.00 0.00 06 normal outlet 0.07 3.25 0.03 18.27 0.17 08 sedimen + decay 0.00 23.35 0.05 0.00 0.00 09 total inflow 0.10 28.15 0.09 107.21 0.35 10 surface outflow 0.07 3.25 0.03 18.27 0.17 11 groundw outflow 0.03 0.00 0.00 0.01 12 total outflow 0.10 3.25 0.03 12.35 0.12 13 total trapped 0.00 24.79 0.06 14 storage increase 0.00 0.00 0.00 15 mass balance check 0.00 0.11 0.00 Load Reduction (%)0.00 88.06 65.73 Device: Grass Swale2.1 Type:SWALE Flow Loads(lbs)Concentrations (ppm) Mass Balance Term acre-ft TSS TP TSS TP 02 upstream device 0.07 3.25 0.03 18.27 0.17 03 infiltrate 0.04 0.67 0.01 6.30 0.12 04 exfiltrate 0.04 0.00 0.00 0.01 05 filtered 0.00 0.67 0.01 0.00 0.00 06 normal outlet 0.03 0.48 0.01 6.60 0.12 08 sedimen + decay 0.00 2.02 0.01 0.00 0.00 09 total inflow 0.07 3.25 0.03 18.27 0.17 10 surface outflow 0.03 0.48 0.01 6.60 0.12 11 groundw outflow 0.04 0.00 0.00 0.01 12 total outflow 0.07 0.48 0.01 2.68 0.06 13 total trapped 0.00 2.69 0.02 14 storage increase 0.00 0.00 0.00 15 mass balance check 0.00 0.08 0.00 Load Reduction (%)0.00 82.73 65.36 Device: Grass Swale3 Type:SWALE Flow Loads(lbs)Concentrations (ppm) Mass Balance Term acre-ft TSS TP TSS TP 01 watershed inflows 0.05 14.42 0.05 107.21 0.35 03 infiltrate 0.03 0.47 0.01 6.45 0.12 04 exfiltrate 0.03 0.00 0.00 0.01 05 filtered 0.00 0.47 0.01 0.00 0.00 06 normal outlet 0.02 0.49 0.01 7.90 0.13 08 sedimen + decay 0.00 13.36 0.03 0.00 0.00 09 total inflow 0.05 14.42 0.05 107.21 0.35 10 surface outflow 0.02 0.49 0.01 7.90 0.13 11 groundw outflow 0.03 0.00 0.00 0.01 12 total outflow 0.05 0.49 0.01 3.61 0.06 13 total trapped 0.00 13.83 0.04 14 storage increase 0.00 0.00 0.00 15 mass balance check 0.00 0.10 0.00 Load Reduction (%)0.00 95.92 80.50 Appendix D – HydroCAD Output 1S Existing to South Property 2S Direct to Parkway 1R Existing to South Property 2R Existing to Parkway 3R Total Site Discharge Routing Diagram for 200515_0515_Boylan Shores_EX Prepared by Civil Methods, Inc., Printed 5/15/2020 HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 1-Year Rainfall=2.49"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 2HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=71,758 sf 1.12% Impervious Runoff Depth=0.73"Subcatchment 1S: Existing to South Property Flow Length=260' Tc=17.7 min CN=77 Runoff=1.34 cfs 0.101 af Runoff Area=18,272 sf 16.59% Impervious Runoff Depth=1.05"Subcatchment 2S: Direct to Parkway Tc=10.0 min CN=83 Runoff=0.66 cfs 0.037 af Inflow=1.34 cfs 0.101 afReach 1R: Existing to South Property Outflow=1.34 cfs 0.101 af Inflow=0.66 cfs 0.037 afReach 2R: Existing to Parkway Outflow=0.66 cfs 0.037 af Inflow=1.82 cfs 0.137 afReach 3R: Total Site Discharge Outflow=1.82 cfs 0.137 af Total Runoff Area = 2.067 ac Runoff Volume = 0.137 af Average Runoff Depth = 0.80" 95.74% Pervious = 1.979 ac 4.26% Impervious = 0.088 ac Type II 24-hr 1-Year Rainfall=2.49"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 3HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing to South Property Runoff =1.34 cfs @ 12.12 hrs, Volume=0.101 af, Depth= 0.73" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 1-Year Rainfall=2.49" Area (sf) CN Description *802 98 70,956 77 Woods, Good, HSG D 71,758 77 Weighted Average 70,956 98.88% Pervious Area 802 1.12% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 14.3 100 0.0650 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.80" 3.4 160 0.0250 0.79 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 17.7 260 Total Summary for Subcatchment 2S: Direct to Parkway Runoff =0.66 cfs @ 12.02 hrs, Volume=0.037 af, Depth= 1.05" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 1-Year Rainfall=2.49" Area (sf) CN Description *3,031 98 15,241 80 >75% Grass cover, Good, HSG D 18,272 83 Weighted Average 15,241 83.41% Pervious Area 3,031 16.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.0 Direct Entry, Summary for Reach 1R: Existing to South Property Inflow Area =1.647 ac, 1.12% Impervious, Inflow Depth = 0.73" for 1-Year event Inflow =1.34 cfs @ 12.12 hrs, Volume=0.101 af Outflow =1.34 cfs @ 12.12 hrs, Volume=0.101 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 1-Year Rainfall=2.49"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 4HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Reach 2R: Existing to Parkway Inflow Area =0.419 ac, 16.59% Impervious, Inflow Depth = 1.05" for 1-Year event Inflow =0.66 cfs @ 12.02 hrs, Volume=0.037 af Outflow =0.66 cfs @ 12.02 hrs, Volume=0.037 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 3R: Total Site Discharge Inflow Area =2.067 ac, 4.26% Impervious, Inflow Depth = 0.80" for 1-Year event Inflow =1.82 cfs @ 12.08 hrs, Volume=0.137 af Outflow =1.82 cfs @ 12.08 hrs, Volume=0.137 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 2-Year Rainfall=2.75"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 5HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=71,758 sf 1.12% Impervious Runoff Depth=0.90"Subcatchment 1S: Existing to South Property Flow Length=260' Tc=17.7 min CN=77 Runoff=1.68 cfs 0.124 af Runoff Area=18,272 sf 16.59% Impervious Runoff Depth=1.25"Subcatchment 2S: Direct to Parkway Tc=10.0 min CN=83 Runoff=0.79 cfs 0.044 af Inflow=1.68 cfs 0.124 afReach 1R: Existing to South Property Outflow=1.68 cfs 0.124 af Inflow=0.79 cfs 0.044 afReach 2R: Existing to Parkway Outflow=0.79 cfs 0.044 af Inflow=2.28 cfs 0.167 afReach 3R: Total Site Discharge Outflow=2.28 cfs 0.167 af Total Runoff Area = 2.067 ac Runoff Volume = 0.167 af Average Runoff Depth = 0.97" 95.74% Pervious = 1.979 ac 4.26% Impervious = 0.088 ac Type II 24-hr 2-Year Rainfall=2.75"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 6HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing to South Property Runoff =1.68 cfs @ 12.11 hrs, Volume=0.124 af, Depth= 0.90" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 2-Year Rainfall=2.75" Area (sf) CN Description *802 98 70,956 77 Woods, Good, HSG D 71,758 77 Weighted Average 70,956 98.88% Pervious Area 802 1.12% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 14.3 100 0.0650 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.80" 3.4 160 0.0250 0.79 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 17.7 260 Total Summary for Subcatchment 2S: Direct to Parkway Runoff =0.79 cfs @ 12.02 hrs, Volume=0.044 af, Depth= 1.25" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 2-Year Rainfall=2.75" Area (sf) CN Description *3,031 98 15,241 80 >75% Grass cover, Good, HSG D 18,272 83 Weighted Average 15,241 83.41% Pervious Area 3,031 16.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.0 Direct Entry, Summary for Reach 1R: Existing to South Property Inflow Area =1.647 ac, 1.12% Impervious, Inflow Depth = 0.90" for 2-Year event Inflow =1.68 cfs @ 12.11 hrs, Volume=0.124 af Outflow =1.68 cfs @ 12.11 hrs, Volume=0.124 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 2-Year Rainfall=2.75"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 7HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Reach 2R: Existing to Parkway Inflow Area =0.419 ac, 16.59% Impervious, Inflow Depth = 1.25" for 2-Year event Inflow =0.79 cfs @ 12.02 hrs, Volume=0.044 af Outflow =0.79 cfs @ 12.02 hrs, Volume=0.044 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 3R: Total Site Discharge Inflow Area =2.067 ac, 4.26% Impervious, Inflow Depth = 0.97" for 2-Year event Inflow =2.28 cfs @ 12.07 hrs, Volume=0.167 af Outflow =2.28 cfs @ 12.07 hrs, Volume=0.167 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.23"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 8HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=71,758 sf 1.12% Impervious Runoff Depth=1.99"Subcatchment 1S: Existing to South Property Flow Length=260' Tc=17.7 min CN=77 Runoff=3.87 cfs 0.274 af Runoff Area=18,272 sf 16.59% Impervious Runoff Depth=2.49"Subcatchment 2S: Direct to Parkway Tc=10.0 min CN=83 Runoff=1.57 cfs 0.087 af Inflow=3.87 cfs 0.274 afReach 1R: Existing to South Property Outflow=3.87 cfs 0.274 af Inflow=1.57 cfs 0.087 afReach 2R: Existing to Parkway Outflow=1.57 cfs 0.087 af Inflow=5.08 cfs 0.361 afReach 3R: Total Site Discharge Outflow=5.08 cfs 0.361 af Total Runoff Area = 2.067 ac Runoff Volume = 0.361 af Average Runoff Depth = 2.09" 95.74% Pervious = 1.979 ac 4.26% Impervious = 0.088 ac Type II 24-hr 10-Year Rainfall=4.23"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 9HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing to South Property Runoff =3.87 cfs @ 12.11 hrs, Volume=0.274 af, Depth= 1.99" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.23" Area (sf) CN Description *802 98 70,956 77 Woods, Good, HSG D 71,758 77 Weighted Average 70,956 98.88% Pervious Area 802 1.12% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 14.3 100 0.0650 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.80" 3.4 160 0.0250 0.79 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 17.7 260 Total Summary for Subcatchment 2S: Direct to Parkway Runoff =1.57 cfs @ 12.01 hrs, Volume=0.087 af, Depth= 2.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.23" Area (sf) CN Description *3,031 98 15,241 80 >75% Grass cover, Good, HSG D 18,272 83 Weighted Average 15,241 83.41% Pervious Area 3,031 16.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.0 Direct Entry, Summary for Reach 1R: Existing to South Property Inflow Area =1.647 ac, 1.12% Impervious, Inflow Depth = 1.99" for 10-Year event Inflow =3.87 cfs @ 12.11 hrs, Volume=0.274 af Outflow =3.87 cfs @ 12.11 hrs, Volume=0.274 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.23"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 10HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Reach 2R: Existing to Parkway Inflow Area =0.419 ac, 16.59% Impervious, Inflow Depth = 2.49" for 10-Year event Inflow =1.57 cfs @ 12.01 hrs, Volume=0.087 af Outflow =1.57 cfs @ 12.01 hrs, Volume=0.087 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 3R: Total Site Discharge Inflow Area =2.067 ac, 4.26% Impervious, Inflow Depth = 2.09" for 10-Year event Inflow =5.08 cfs @ 12.07 hrs, Volume=0.361 af Outflow =5.08 cfs @ 12.07 hrs, Volume=0.361 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 100-Year Rainfall=7.25"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 11HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=71,758 sf 1.12% Impervious Runoff Depth=4.59"Subcatchment 1S: Existing to South Property Flow Length=260' Tc=17.7 min CN=77 Runoff=8.91 cfs 0.630 af Runoff Area=18,272 sf 16.59% Impervious Runoff Depth=5.26"Subcatchment 2S: Direct to Parkway Tc=10.0 min CN=83 Runoff=3.23 cfs 0.184 af Inflow=8.91 cfs 0.630 afReach 1R: Existing to South Property Outflow=8.91 cfs 0.630 af Inflow=3.23 cfs 0.184 afReach 2R: Existing to Parkway Outflow=3.23 cfs 0.184 af Inflow=11.42 cfs 0.814 afReach 3R: Total Site Discharge Outflow=11.42 cfs 0.814 af Total Runoff Area = 2.067 ac Runoff Volume = 0.814 af Average Runoff Depth = 4.73" 95.74% Pervious = 1.979 ac 4.26% Impervious = 0.088 ac Type II 24-hr 100-Year Rainfall=7.25"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 12HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Existing to South Property Runoff =8.91 cfs @ 12.10 hrs, Volume=0.630 af, Depth= 4.59" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 100-Year Rainfall=7.25" Area (sf) CN Description *802 98 70,956 77 Woods, Good, HSG D 71,758 77 Weighted Average 70,956 98.88% Pervious Area 802 1.12% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 14.3 100 0.0650 0.12 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.80" 3.4 160 0.0250 0.79 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 17.7 260 Total Summary for Subcatchment 2S: Direct to Parkway Runoff =3.23 cfs @ 12.01 hrs, Volume=0.184 af, Depth= 5.26" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 100-Year Rainfall=7.25" Area (sf) CN Description *3,031 98 15,241 80 >75% Grass cover, Good, HSG D 18,272 83 Weighted Average 15,241 83.41% Pervious Area 3,031 16.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.0 Direct Entry, Summary for Reach 1R: Existing to South Property Inflow Area =1.647 ac, 1.12% Impervious, Inflow Depth = 4.59" for 100-Year event Inflow =8.91 cfs @ 12.10 hrs, Volume=0.630 af Outflow =8.91 cfs @ 12.10 hrs, Volume=0.630 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 100-Year Rainfall=7.25"200515_0515_Boylan Shores_EX Printed 5/15/2020Prepared by Civil Methods, Inc. Page 13HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Reach 2R: Existing to Parkway Inflow Area =0.419 ac, 16.59% Impervious, Inflow Depth = 5.26" for 100-Year event Inflow =3.23 cfs @ 12.01 hrs, Volume=0.184 af Outflow =3.23 cfs @ 12.01 hrs, Volume=0.184 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 3R: Total Site Discharge Inflow Area =2.067 ac, 4.26% Impervious, Inflow Depth = 4.73" for 100-Year event Inflow =11.42 cfs @ 12.07 hrs, Volume=0.814 af Outflow =11.42 cfs @ 12.07 hrs, Volume=0.814 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs 1 Proposed to Basin 2 Direct to East 3 Direct to South 1R To Private Property South 2R Proposed to Parkway Sewer 3R Total Site Discharge 2P Biofillter 1 Routing Diagram for 200515_0515_Boylan Shores_PR Prepared by Civil Methods, Inc., Printed 5/15/2020 HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 1-Year Rainfall=2.49"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 2HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=64,806 sf 24.91% Impervious Runoff Depth=1.11"Subcatchment 1: Proposed to Basin Flow Length=260' Tc=16.0 min CN=84 Runoff=2.04 cfs 0.137 af Runoff Area=19,840 sf 9.45% Impervious Runoff Depth=0.99"Subcatchment 2: Direct to East Tc=10.0 min CN=82 Runoff=0.68 cfs 0.038 af Runoff Area=4,994 sf 25.03% Impervious Runoff Depth=1.17"Subcatchment 3: Direct to South Tc=6.0 min CN=85 Runoff=0.23 cfs 0.011 af Inflow=0.23 cfs 0.011 afReach 1R: To Private Property South Outflow=0.23 cfs 0.011 af Inflow=0.71 cfs 0.175 afReach 2R: Proposed to Parkway Sewer Outflow=0.71 cfs 0.175 af Inflow=0.92 cfs 0.186 afReach 3R: Total Site Discharge Outflow=0.92 cfs 0.186 af Peak Elev=969.25' Storage=3,839 cf Inflow=2.04 cfs 0.137 afPond 2P: Biofillter 1 Outflow=0.06 cfs 0.137 af Total Runoff Area = 2.058 ac Runoff Volume = 0.186 af Average Runoff Depth = 1.09" 78.50% Pervious = 1.615 ac 21.50% Impervious = 0.442 ac Type II 24-hr 1-Year Rainfall=2.49"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 3HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Proposed to Basin Runoff =2.04 cfs @ 12.09 hrs, Volume=0.137 af, Depth= 1.11" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 1-Year Rainfall=2.49" Area (sf) CN Description *16,145 98 48,661 80 >75% Grass cover, Good, HSG D 64,806 84 Weighted Average 48,661 75.09% Pervious Area 16,145 24.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.8 70 0.0650 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.80" 2.5 30 0.0650 0.20 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 2.7 160 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 16.0 260 Total Summary for Subcatchment 2: Direct to East Runoff =0.68 cfs @ 12.02 hrs, Volume=0.038 af, Depth= 0.99" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 1-Year Rainfall=2.49" Area (sf) CN Description *1,875 98 17,965 80 >75% Grass cover, Good, HSG D 19,840 82 Weighted Average 17,965 90.55% Pervious Area 1,875 9.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.0 Direct Entry, Summary for Subcatchment 3: Direct to South Runoff =0.23 cfs @ 11.97 hrs, Volume=0.011 af, Depth= 1.17" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 1-Year Rainfall=2.49" Type II 24-hr 1-Year Rainfall=2.49"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 4HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Area (sf) CN Description *1,250 98 *3,744 80 4,994 85 Weighted Average 3,744 74.97% Pervious Area 1,250 25.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 6.0 Direct Entry, Summary for Reach 1R: To Private Property South Inflow Area =0.115 ac, 25.03% Impervious, Inflow Depth = 1.17" for 1-Year event Inflow =0.23 cfs @ 11.97 hrs, Volume=0.011 af Outflow =0.23 cfs @ 11.97 hrs, Volume=0.011 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 2R: Proposed to Parkway Sewer Inflow Area =1.943 ac, 21.29% Impervious, Inflow Depth = 1.08" for 1-Year event Inflow =0.71 cfs @ 12.02 hrs, Volume=0.175 af Outflow =0.71 cfs @ 12.02 hrs, Volume=0.175 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 3R: Total Site Discharge Inflow Area =2.058 ac, 21.50% Impervious, Inflow Depth = 1.09" for 1-Year event Inflow =0.92 cfs @ 12.01 hrs, Volume=0.186 af Outflow =0.92 cfs @ 12.01 hrs, Volume=0.186 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Pond 2P: Biofillter 1 Inflow Area =1.488 ac, 24.91% Impervious, Inflow Depth = 1.11" for 1-Year event Inflow =2.04 cfs @ 12.09 hrs, Volume=0.137 af Outflow =0.06 cfs @ 17.39 hrs, Volume=0.137 af, Atten= 97%, Lag= 318.0 min Primary =0.06 cfs @ 17.39 hrs, Volume=0.137 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs / 3 Peak Elev= 969.25' @ 17.39 hrs Surf.Area= 3,030 sf Storage= 3,839 cf Plug-Flow detention time= 813.9 min calculated for 0.137 af (100% of inflow) Center-of-Mass det. time= 814.4 min ( 1,662.1 - 847.7 ) Type II 24-hr 1-Year Rainfall=2.49"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 5HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 967.50'20,263 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 967.50 1,350 0 0 969.50 3,267 4,617 4,617 970.00 4,530 1,949 6,566 971.00 6,268 5,399 11,965 971.50 7,992 3,565 15,530 972.00 10,940 4,733 20,263 Device Routing Invert Outlet Devices #1 Primary 965.50'12.0" Round Culvert L= 302.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 965.50' / 964.40' S= 0.0036 '/' Cc= 0.900 n= 0.011, Flow Area= 0.79 sf #2 Device 1 967.50'0.800 in/hr Exfiltration to underdrain over Surface area #3 Device 1 969.50'6.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 971.00'4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=0.06 cfs @ 17.39 hrs HW=969.25' (Free Discharge) 1=Culvert (Passes 0.06 cfs of 4.30 cfs potential flow) 2=Exfiltration to underdrain (Exfiltration Controls 0.06 cfs) 3=Orifice/Grate ( Controls 0.00 cfs) 4=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) Type II 24-hr 2-Year Rainfall=2.75"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 6HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=64,806 sf 24.91% Impervious Runoff Depth=1.31"Subcatchment 1: Proposed to Basin Flow Length=260' Tc=16.0 min CN=84 Runoff=2.43 cfs 0.163 af Runoff Area=19,840 sf 9.45% Impervious Runoff Depth=1.19"Subcatchment 2: Direct to East Tc=10.0 min CN=82 Runoff=0.82 cfs 0.045 af Runoff Area=4,994 sf 25.03% Impervious Runoff Depth=1.38"Subcatchment 3: Direct to South Tc=6.0 min CN=85 Runoff=0.27 cfs 0.013 af Inflow=0.27 cfs 0.013 afReach 1R: To Private Property South Outflow=0.27 cfs 0.013 af Inflow=0.85 cfs 0.208 afReach 2R: Proposed to Parkway Sewer Outflow=0.85 cfs 0.208 af Inflow=1.10 cfs 0.221 afReach 3R: Total Site Discharge Outflow=1.10 cfs 0.221 af Peak Elev=969.52' Storage=4,675 cf Inflow=2.43 cfs 0.163 afPond 2P: Biofillter 1 Outflow=0.06 cfs 0.163 af Total Runoff Area = 2.058 ac Runoff Volume = 0.221 af Average Runoff Depth = 1.29" 78.50% Pervious = 1.615 ac 21.50% Impervious = 0.442 ac Type II 24-hr 2-Year Rainfall=2.75"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 7HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Proposed to Basin Runoff =2.43 cfs @ 12.09 hrs, Volume=0.163 af, Depth= 1.31" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 2-Year Rainfall=2.75" Area (sf) CN Description *16,145 98 48,661 80 >75% Grass cover, Good, HSG D 64,806 84 Weighted Average 48,661 75.09% Pervious Area 16,145 24.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.8 70 0.0650 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.80" 2.5 30 0.0650 0.20 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 2.7 160 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 16.0 260 Total Summary for Subcatchment 2: Direct to East Runoff =0.82 cfs @ 12.02 hrs, Volume=0.045 af, Depth= 1.19" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 2-Year Rainfall=2.75" Area (sf) CN Description *1,875 98 17,965 80 >75% Grass cover, Good, HSG D 19,840 82 Weighted Average 17,965 90.55% Pervious Area 1,875 9.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.0 Direct Entry, Summary for Subcatchment 3: Direct to South Runoff =0.27 cfs @ 11.97 hrs, Volume=0.013 af, Depth= 1.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 2-Year Rainfall=2.75" Type II 24-hr 2-Year Rainfall=2.75"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 8HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Area (sf) CN Description *1,250 98 *3,744 80 4,994 85 Weighted Average 3,744 74.97% Pervious Area 1,250 25.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 6.0 Direct Entry, Summary for Reach 1R: To Private Property South Inflow Area =0.115 ac, 25.03% Impervious, Inflow Depth = 1.38" for 2-Year event Inflow =0.27 cfs @ 11.97 hrs, Volume=0.013 af Outflow =0.27 cfs @ 11.97 hrs, Volume=0.013 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 2R: Proposed to Parkway Sewer Inflow Area =1.943 ac, 21.29% Impervious, Inflow Depth = 1.28" for 2-Year event Inflow =0.85 cfs @ 12.02 hrs, Volume=0.208 af Outflow =0.85 cfs @ 12.02 hrs, Volume=0.208 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 3R: Total Site Discharge Inflow Area =2.058 ac, 21.50% Impervious, Inflow Depth = 1.29" for 2-Year event Inflow =1.10 cfs @ 12.01 hrs, Volume=0.221 af Outflow =1.10 cfs @ 12.01 hrs, Volume=0.221 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Pond 2P: Biofillter 1 Inflow Area =1.488 ac, 24.91% Impervious, Inflow Depth = 1.31" for 2-Year event Inflow =2.43 cfs @ 12.09 hrs, Volume=0.163 af Outflow =0.06 cfs @ 17.61 hrs, Volume=0.163 af, Atten= 97%, Lag= 331.3 min Primary =0.06 cfs @ 17.61 hrs, Volume=0.163 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs / 3 Peak Elev= 969.52' @ 17.61 hrs Surf.Area= 3,312 sf Storage= 4,675 cf Plug-Flow detention time= 908.5 min calculated for 0.163 af (100% of inflow) Center-of-Mass det. time= 908.2 min ( 1,751.0 - 842.8 ) Type II 24-hr 2-Year Rainfall=2.75"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 9HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 967.50'20,263 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 967.50 1,350 0 0 969.50 3,267 4,617 4,617 970.00 4,530 1,949 6,566 971.00 6,268 5,399 11,965 971.50 7,992 3,565 15,530 972.00 10,940 4,733 20,263 Device Routing Invert Outlet Devices #1 Primary 965.50'12.0" Round Culvert L= 302.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 965.50' / 964.40' S= 0.0036 '/' Cc= 0.900 n= 0.011, Flow Area= 0.79 sf #2 Device 1 967.50'0.800 in/hr Exfiltration to underdrain over Surface area #3 Device 1 969.50'6.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 971.00'4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=0.06 cfs @ 17.61 hrs HW=969.52' (Free Discharge) 1=Culvert (Passes 0.06 cfs of 4.44 cfs potential flow) 2=Exfiltration to underdrain (Exfiltration Controls 0.06 cfs) 3=Orifice/Grate (Orifice Controls 0.00 cfs @ 0.45 fps) 4=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) Type II 24-hr 10-Year Rainfall=4.23"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 10HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=64,806 sf 24.91% Impervious Runoff Depth=2.57"Subcatchment 1: Proposed to Basin Flow Length=260' Tc=16.0 min CN=84 Runoff=4.75 cfs 0.319 af Runoff Area=19,840 sf 9.45% Impervious Runoff Depth=2.40"Subcatchment 2: Direct to East Tc=10.0 min CN=82 Runoff=1.65 cfs 0.091 af Runoff Area=4,994 sf 25.03% Impervious Runoff Depth=2.66"Subcatchment 3: Direct to South Tc=6.0 min CN=85 Runoff=0.52 cfs 0.025 af Inflow=0.52 cfs 0.025 afReach 1R: To Private Property South Outflow=0.52 cfs 0.025 af Inflow=1.70 cfs 0.410 afReach 2R: Proposed to Parkway Sewer Outflow=1.70 cfs 0.410 af Inflow=2.17 cfs 0.436 afReach 3R: Total Site Discharge Outflow=2.17 cfs 0.436 af Peak Elev=970.10' Storage=7,047 cf Inflow=4.75 cfs 0.319 afPond 2P: Biofillter 1 Outflow=0.65 cfs 0.319 af Total Runoff Area = 2.058 ac Runoff Volume = 0.436 af Average Runoff Depth = 2.54" 78.50% Pervious = 1.615 ac 21.50% Impervious = 0.442 ac Type II 24-hr 10-Year Rainfall=4.23"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 11HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Proposed to Basin Runoff =4.75 cfs @ 12.08 hrs, Volume=0.319 af, Depth= 2.57" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.23" Area (sf) CN Description *16,145 98 48,661 80 >75% Grass cover, Good, HSG D 64,806 84 Weighted Average 48,661 75.09% Pervious Area 16,145 24.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.8 70 0.0650 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.80" 2.5 30 0.0650 0.20 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 2.7 160 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 16.0 260 Total Summary for Subcatchment 2: Direct to East Runoff =1.65 cfs @ 12.01 hrs, Volume=0.091 af, Depth= 2.40" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.23" Area (sf) CN Description *1,875 98 17,965 80 >75% Grass cover, Good, HSG D 19,840 82 Weighted Average 17,965 90.55% Pervious Area 1,875 9.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.0 Direct Entry, Summary for Subcatchment 3: Direct to South Runoff =0.52 cfs @ 11.97 hrs, Volume=0.025 af, Depth= 2.66" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 10-Year Rainfall=4.23" Type II 24-hr 10-Year Rainfall=4.23"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 12HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Area (sf) CN Description *1,250 98 *3,744 80 4,994 85 Weighted Average 3,744 74.97% Pervious Area 1,250 25.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 6.0 Direct Entry, Summary for Reach 1R: To Private Property South Inflow Area =0.115 ac, 25.03% Impervious, Inflow Depth = 2.66" for 10-Year event Inflow =0.52 cfs @ 11.97 hrs, Volume=0.025 af Outflow =0.52 cfs @ 11.97 hrs, Volume=0.025 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 2R: Proposed to Parkway Sewer Inflow Area =1.943 ac, 21.29% Impervious, Inflow Depth = 2.53" for 10-Year event Inflow =1.70 cfs @ 12.02 hrs, Volume=0.410 af Outflow =1.70 cfs @ 12.02 hrs, Volume=0.410 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 3R: Total Site Discharge Inflow Area =2.058 ac, 21.50% Impervious, Inflow Depth = 2.54" for 10-Year event Inflow =2.17 cfs @ 12.00 hrs, Volume=0.436 af Outflow =2.17 cfs @ 12.00 hrs, Volume=0.436 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Pond 2P: Biofillter 1 Inflow Area =1.488 ac, 24.91% Impervious, Inflow Depth = 2.57" for 10-Year event Inflow =4.75 cfs @ 12.08 hrs, Volume=0.319 af Outflow =0.65 cfs @ 12.63 hrs, Volume=0.319 af, Atten= 86%, Lag= 32.7 min Primary =0.65 cfs @ 12.63 hrs, Volume=0.319 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs / 3 Peak Elev= 970.10' @ 12.63 hrs Surf.Area= 4,711 sf Storage= 7,047 cf Plug-Flow detention time= 556.4 min calculated for 0.319 af (100% of inflow) Center-of-Mass det. time= 557.4 min ( 1,380.9 - 823.5 ) Type II 24-hr 10-Year Rainfall=4.23"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 13HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 967.50'20,263 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 967.50 1,350 0 0 969.50 3,267 4,617 4,617 970.00 4,530 1,949 6,566 971.00 6,268 5,399 11,965 971.50 7,992 3,565 15,530 972.00 10,940 4,733 20,263 Device Routing Invert Outlet Devices #1 Primary 965.50'12.0" Round Culvert L= 302.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 965.50' / 964.40' S= 0.0036 '/' Cc= 0.900 n= 0.011, Flow Area= 0.79 sf #2 Device 1 967.50'0.800 in/hr Exfiltration to underdrain over Surface area #3 Device 1 969.50'6.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 971.00'4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=0.65 cfs @ 12.63 hrs HW=970.10' (Free Discharge) 1=Culvert (Passes 0.65 cfs of 4.75 cfs potential flow) 2=Exfiltration to underdrain (Exfiltration Controls 0.09 cfs) 3=Orifice/Grate (Orifice Controls 0.56 cfs @ 2.86 fps) 4=Sharp-Crested Rectangular Weir ( Controls 0.00 cfs) Type II 24-hr 100-Year Rainfall=7.25"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 14HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Time span=0.00-72.00 hrs, dt=0.05 hrs, 1441 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Runoff Area=64,806 sf 24.91% Impervious Runoff Depth=5.38"Subcatchment 1: Proposed to Basin Flow Length=260' Tc=16.0 min CN=84 Runoff=9.67 cfs 0.667 af Runoff Area=19,840 sf 9.45% Impervious Runoff Depth=5.15"Subcatchment 2: Direct to East Tc=10.0 min CN=82 Runoff=3.45 cfs 0.196 af Runoff Area=4,994 sf 25.03% Impervious Runoff Depth=5.49"Subcatchment 3: Direct to South Tc=6.0 min CN=85 Runoff=1.02 cfs 0.052 af Inflow=1.02 cfs 0.052 afReach 1R: To Private Property South Outflow=1.02 cfs 0.052 af Inflow=4.23 cfs 0.862 afReach 2R: Proposed to Parkway Sewer Outflow=4.23 cfs 0.862 af Inflow=5.11 cfs 0.915 afReach 3R: Total Site Discharge Outflow=5.11 cfs 0.915 af Peak Elev=971.26' Storage=13,734 cf Inflow=9.67 cfs 0.667 afPond 2P: Biofillter 1 Outflow=3.04 cfs 0.667 af Total Runoff Area = 2.058 ac Runoff Volume = 0.915 af Average Runoff Depth = 5.33" 78.50% Pervious = 1.615 ac 21.50% Impervious = 0.442 ac Type II 24-hr 100-Year Rainfall=7.25"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 15HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1: Proposed to Basin Runoff =9.67 cfs @ 12.08 hrs, Volume=0.667 af, Depth= 5.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 100-Year Rainfall=7.25" Area (sf) CN Description *16,145 98 48,661 80 >75% Grass cover, Good, HSG D 64,806 84 Weighted Average 48,661 75.09% Pervious Area 16,145 24.91% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.8 70 0.0650 0.11 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 2.80" 2.5 30 0.0650 0.20 Sheet Flow, Grass: Short n= 0.150 P2= 2.80" 2.7 160 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 16.0 260 Total Summary for Subcatchment 2: Direct to East Runoff =3.45 cfs @ 12.01 hrs, Volume=0.196 af, Depth= 5.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 100-Year Rainfall=7.25" Area (sf) CN Description *1,875 98 17,965 80 >75% Grass cover, Good, HSG D 19,840 82 Weighted Average 17,965 90.55% Pervious Area 1,875 9.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 10.0 Direct Entry, Summary for Subcatchment 3: Direct to South Runoff =1.02 cfs @ 11.96 hrs, Volume=0.052 af, Depth= 5.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Type II 24-hr 100-Year Rainfall=7.25" Type II 24-hr 100-Year Rainfall=7.25"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 16HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Area (sf) CN Description *1,250 98 *3,744 80 4,994 85 Weighted Average 3,744 74.97% Pervious Area 1,250 25.03% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet)(ft/ft) (ft/sec)(cfs) 6.0 Direct Entry, Summary for Reach 1R: To Private Property South Inflow Area =0.115 ac, 25.03% Impervious, Inflow Depth = 5.49" for 100-Year event Inflow =1.02 cfs @ 11.96 hrs, Volume=0.052 af Outflow =1.02 cfs @ 11.96 hrs, Volume=0.052 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 2R: Proposed to Parkway Sewer Inflow Area =1.943 ac, 21.29% Impervious, Inflow Depth = 5.32" for 100-Year event Inflow =4.23 cfs @ 12.02 hrs, Volume=0.862 af Outflow =4.23 cfs @ 12.02 hrs, Volume=0.862 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Reach 3R: Total Site Discharge Inflow Area =2.058 ac, 21.50% Impervious, Inflow Depth = 5.33" for 100-Year event Inflow =5.11 cfs @ 12.01 hrs, Volume=0.915 af Outflow =5.11 cfs @ 12.01 hrs, Volume=0.915 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Summary for Pond 2P: Biofillter 1 Inflow Area =1.488 ac, 24.91% Impervious, Inflow Depth = 5.38" for 100-Year event Inflow =9.67 cfs @ 12.08 hrs, Volume=0.667 af Outflow =3.04 cfs @ 12.34 hrs, Volume=0.667 af, Atten= 69%, Lag= 16.0 min Primary =3.04 cfs @ 12.34 hrs, Volume=0.667 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs / 3 Peak Elev= 971.26' @ 12.34 hrs Surf.Area= 7,175 sf Storage= 13,734 cf Plug-Flow detention time= 325.7 min calculated for 0.666 af (100% of inflow) Center-of-Mass det. time= 326.8 min ( 1,129.4 - 802.7 ) Type II 24-hr 100-Year Rainfall=7.25"200515_0515_Boylan Shores_PR Printed 5/15/2020Prepared by Civil Methods, Inc. Page 17HydroCAD® 10.00-24 s/n 07283 © 2018 HydroCAD Software Solutions LLC Volume Invert Avail.Storage Storage Description #1 967.50'20,263 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft)(cubic-feet)(cubic-feet) 967.50 1,350 0 0 969.50 3,267 4,617 4,617 970.00 4,530 1,949 6,566 971.00 6,268 5,399 11,965 971.50 7,992 3,565 15,530 972.00 10,940 4,733 20,263 Device Routing Invert Outlet Devices #1 Primary 965.50'12.0" Round Culvert L= 302.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 965.50' / 964.40' S= 0.0036 '/' Cc= 0.900 n= 0.011, Flow Area= 0.79 sf #2 Device 1 967.50'0.800 in/hr Exfiltration to underdrain over Surface area #3 Device 1 969.50'6.0" Vert. Orifice/Grate C= 0.600 #4 Device 1 971.00'4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=3.03 cfs @ 12.34 hrs HW=971.26' (Free Discharge) 1=Culvert (Passes 3.03 cfs of 5.30 cfs potential flow) 2=Exfiltration to underdrain (Exfiltration Controls 0.13 cfs) 3=Orifice/Grate (Orifice Controls 1.16 cfs @ 5.92 fps) 4=Sharp-Crested Rectangular Weir (Weir Controls 1.73 cfs @ 1.67 fps) Appendix E – Downstream Sewer (Minnewashta Pkwy) Design Review PIPE SEWER DESIGN - RATIONAL METHOD FOR GRAVITY FLOW CAPACITY PROJECT:Boylan Shores - Downstream Sewer Analysis (Minnewashta Parkway) CLIENT: DATE: MANNING'S N:0.013 DESIGN STORM FREQUENCY:10 YEARS From To Area Area Tc i Q SUM OF Tc i Q S Pipe Capacity Vel. At Pipe Time ID or Location Struct.Struct.(sq ft)(acres)C AxC (min.)(in/hr)(cfs)AxC (min.)(in/hr)(cfs)(%)Size (cfs)Fl. Flow Length in Pipe (in)(fps)(ft)(min) 10yr Q from Basin OCS 19 1.70 0.37 12.00 2.17 2.76 150.0 0.91 Parkway CB19 MH18 19177 0.44 0.50 0.22 6.00 6.80 1.50 3.20 1.27 12.00 4.02 5.11 284.0 0.93 IDENTIFICATION 5/15/2020 Inlet Pipe RUNOFF COMPUTATION SEWER DESIGN