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HomeMy WebLinkAbout2021-09-14 Stormwater Management Plan Julie Hultman From: Scott Richards <scott@planningco.com> Sent: Wednesday, September 22, 2021 4:31 PM To: Lee Mann;Julie Hultman; Eric Johnson Subject: Fwd: Park Dental Oak Park Heights Attachments: 21 09-14 Park Dental - St. Croix Valley SMP.pdf; 21210A-WA-PPLAT-09-17-21.pdf; 21210A-WA-FPLAT-09-17-21.pdf Follow Up Flag: Follow up Flag Status: Flagged Eric, Lee and Julie: Here the storm water information and preliminary/final plat. Let me know if you need any more information. Scott Sent from my iPhone Begin forwarded message: From:Vicki VanDell<VVanDell@loucksinc.com> Date:September 22, 2021 at 1:54:05 PM CDT To: Scott@planningco.com Cc: Ross Hedlund <ross.hedlund@frauenshuh.com>,Zach Webber<ZWebber@loucksinc.com>,Jonah Ritter<jonahr@sra-mn.com>, Nathan Rauner<nathanr@sra-mn.com>, Dylan McCormick <dylan.mccormick@frauenshuh.com> Subject: Park Dental Oak Park Heights Scott, I have attached the Stormwater Management Plan and the plats. Let me know if you need additional information. Thanks, VICKI VANDELL, PE (MN) 7S3 496.6720 C 612 559, 731 LOUCKS 1     Stormwater Management Plan PARK DENTAL – ST. CROIX VALLEY Oak Park Heights, MN Frauenshuh Prepared by Loucks September 14, 2021 Loucks Project No. 21210.0 PARK DENTAL – ST. CROIX VALLEY Oak Park Heights, MN Stormwater Management Plan I hereby certify that this plan, specification or report was prepared by me or under my direct supervision and that I am a duly Registered Professional Engineer under the laws of the State of Minnesota. _______________________________ Zachary H. Webber, P.E. Minnesota Registration No. 56092 September 14, 2021 Stormwater Management Plan September 14, 2021 Park Dental – St. Croix Valley – Oak Park Heights, MN PARK DENTAL – ST. CROIX VALLEY Oak Park Heights, MN Stormwater Management Plan Table of Contents Page Number Introduction .................................................................................................................................. 1 Methodology ................................................................................................................................ 1 Existing Conditions ....................................................................................................................... 1 Proposed Conditions .................................................................................................................... 2 Requirements and Results………………....................................................................................... 2 Storm Sewer Design ..................................................................................................................... 3 Erosion and Sediment Control ..................................................................................................... 3 Best Management Practices ......................................................................................................... 3 Conclusion .................................................................................................................................... 3 Appendices HydroCAD Report, Existing Conditions - 2, 10 & 100 Year Events ............................ Appendix A HydroCAD Report, Proposed Conditions - 2, 10 & 100 Year Events .......................... Appendix B Storm Sewer Pipe Sizing ............................................................................................. Appendix C Geotechnical Exploration Report .............................................................................. Appendix D Stormwater Management Plan September 14, 2021 Park Dental – St. Croix Valley – Oak Park Heights, MN Page 1 PARK DENTAL – ST. CROIX VALLEY Oak Park Heights, MN Stormwater Management Plan Introduction This stormwater management plan was created for the Park Dental – St. Croix Valley redevelopment project located at 13961 60th Street North. The project consists of a parcel 1.493 acres in size. The project consists of demolishing three existing office buildings, associated parking lot, and building utilities. The proposed redevelopment includes a one-story office building, surface parking lot, utilities, and stormwater facilities. Included in this Stormwater Management Plan are calculations for the existing and proposed conditions. Methodology The stormwater calculations were made utilizing the stormwater-modeling program HydroCAD 10.10. Calculations were performed for the Atlas 14-24-hour 2-year, 10-year, and 100-year rainfall events of 2.8 inches, 4.3 inches, and 7.3 inches respectively as listed in the watershed management plan. The Middle St. Croix Watershed Management Organization (MSCWMO) requires the following: Rate Control - The newly developed or redeveloped peak rate shall not exceed the existing peak rate runoff rates for the 2, 10, and 100 year storm events for all points where discharge leaves the site during all phases of development. Volume Control - 1.1 inches of runoff from the impervious surfaces shall be captured and retained on site. Existing Conditions The site consists of three existing buildings, surface parking lot, and green space. The majority of the site sheet flows offsite to the north directly to 60th Street N. (DA-1E). Area DA-2E flows offsite to the southwest and is collected by an existing storm sewer line. The remaining area DA-3E is a small portion of the site that sheet flows offsite to the neighboring property to the east. (See attached existing drainage map). There are no wetlands within the development site. Stormwater Management Plan September 14, 2021 Park Dental – St. Croix Valley – Oak Park Heights, MN Page 2 The following table shows the existing runoff rates: EXISTING CONDITIONS Subcatchment Area Description 2 Year Runoff Rate (cfs) 10 Year Runoff Rate (cfs) 100 Year Runoff Rate (cfs) DA-1E Runoff Offsite to North 4.74 7.58 13.75 DA-2E Runoff Offsite to Southwest 0.35 0.68 1.45 DA-3E Runoff Offsite to East 0.01 0.04 0.12 Proposed Conditions The proposed project consists of an office building, surface parking area, and two stormwater management facilities. Access to the site is from 60th Street N. The proposed site is split up into three areas, two of which discharge to the north. Drainage area DA-1Pa is the existing right of way that flows directly to the storm sewer system in 60th Street N. Drainage area DA-1Pb is collected by a private storm sewer system on site and conveyed to infiltration basin 1 (1B). Drainage area DA-2P is the back side of the site and sheet flows through rain guardians to infiltration basin 2 (2B). Runoff to the east will be eliminated. The following table shows the proposed runoff rates: PROPOSED CONDITIONS Subcatchment Area Description 2 Year Runoff Rate (cfs) 10 Year Runoff Rate (cfs) 100 Year Runoff Rate (cfs) 1L Total to North 0.61 2.54 5.92 2B Total to Southwest 0.00 0.00 1.44 Requirements and Results Rate Control Rate control is required to restrict the runoff discharge from the proposed conditions to be equal to or less than the existing runoff rate. The results of the calculations show the following: Stormwater Management Plan September 14, 2021 Park Dental – St. Croix Valley – Oak Park Heights, MN Page 3 Storm Event Existing Discharge Rate (cfs) Offsite to North Model ID – DA-1E Proposed Discharge Rate (cfs) Total to North Model ID – 1L ∆ (cfs) 2 Yr 4.74 0.61 -4.13 10 Yr 7.58 2.54 -5.04 100 Yr 13.75 5.92 -7.83 Storm Event Existing Discharge Rate (cfs) Offsite to Southwest Model ID – DA-2E Proposed Discharge Rate (cfs) Total to Southwest Model ID – 2B ∆ (cfs) 2 Yr 0.35 0.00 -0.35 10 Yr 0.68 0.00 -0.68 100 Yr 1.45 1.44 -0.01 Rate control is met. Volume Control Volume control is required to infiltrate the volume of 1.1 inch of runoff from the impervious surface area. Based on the soil boring logs, as prepared by American Engineering Test, Inc., the underlying soils (SP-SM, HSG A/B) are conducive for infiltration. An infiltration rate of 0.45 in/hr was used as the most conservative scenario. The infiltration basins shall drain dry in 48 hours so a maximum depth of 1.8 feet was used for both basins. The 1.1 inch runoff volume = 0.882 ac of new impervious surface X 1.1” = 3,522 cf. The proposed water quality volume below the outlet for infiltration basin 1 (1B) is 2,518 cf. The proposed water quality volume below the outlet for infiltration basin 2 (2B) is 1,809 cf. The total volume is 4,327 cf and meets the required volume of 3,522 cf. Volume control is met. Storm Sewer Design The storm sewer is designed for a 10 year storm event. The storm sewer system will collect the majority of the runoff from the proposed development. Erosion and Sediment Control Erosion and sediment control measures will be constructed as shown on the plans. All areas to be re-vegetated will be seeded and mulched. Concentrated flow areas will receive an Stormwater Management Plan September 14, 2021 Park Dental – St. Croix Valley – Oak Park Heights, MN Page 4 appropriate erosion control blanket. Silt fence perimeter sediment controls will be placed prior to any construction activity. Best Management Practices Best management practices (BMP’s) will be implemented during construction per the project Stormwater Pollution Prevention Plan (SWPPP). The final SWPPP will be prepared as part of the construction documents as required and updated as the development occurs. Proposed BMP’s will minimize erosion and manage sedimentation as required by the National Pollution Discharge Elimination System (NPDES). During construction, erosion control measures will include dust control, silt fencing, inlet protection, a temporary rock construction entrance, and post construction silt fence. Post construction silt fence is designed to keep sediment out of the infiltration basins until the upstream area is fully established. Permanent BMP’s will include two infiltration basins and turf establishment of all disturbed areas. Conclusion The proposed Stormwater Management Plan for the Park Dental – St. Croix Valley redevelopment project is designed to meet City and the Watershed’s stormwater requirements. The plan provides an improved solution for the conveyance of stormwater from this site by maintaining peak runoff rates from existing conditions and reducing runoff volume offsite. Appendix A HydroCAD Report – Existing Conditions – 2, 10 & 100 Year Events EXISTING DA-1E Offsite to North DA-2E Offsite to Southwest DA-3E Offsite to East Routing Diagram for 21210 - St. Croix Valley Park Dental Prepared by Loucks, Printed 9/14/2021 HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 2HydroCAD® 10.10-4b s/n 02676 © 2020 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=55,435 sf 87.58% Impervious Runoff Depth=2.06"Subcatchment DA-1E: Offsite to North Flow Length=269' Slope=0.0170 '/' Tc=3.1 min CN=93 Runoff=4.74 cfs 0.219 af Runoff Area=8,649 sf 57.16% Impervious Runoff Depth=1.22"Subcatchment DA-2E: Offsite to Southwest Flow Length=167' Tc=11.3 min CN=82 Runoff=0.35 cfs 0.020 af Runoff Area=962 sf 0.00% Impervious Runoff Depth=0.29"Subcatchment DA-3E: Offsite to East Flow Length=35' Slope=0.0430 '/' Tc=3.3 min CN=61 Runoff=0.01 cfs 0.001 af Total Runoff Area = 1.493 ac Runoff Volume = 0.240 af Average Runoff Depth = 1.93" 17.76% Pervious = 0.265 ac 82.24% Impervious = 1.228 ac Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 3HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-1E: Offsite to North [49] Hint: Tc<2dt may require smaller dt Runoff = 4.74 cfs @ 11.93 hrs, Volume= 0.219 af, Depth= 2.06" 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=2.80" Area (sf) CN Description 48,550 98 Paved parking, HSG B 6,885 61 >75% Grass cover, Good, HSG B 55,435 93 Weighted Average 6,885 12.42% Pervious Area 48,550 87.58% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.1 269 0.0170 1.47 Sheet Flow, Pavement Smooth surfaces n= 0.011 P2= 2.80" Subcatchment DA-1E: Offsite to North Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)5 4 3 2 1 0 Type II 24-hr 2 Year Rainfall=2.80" Runoff Area=55,435 sf Runoff Volume=0.219 af Runoff Depth=2.06" Flow Length=269' Slope=0.0170 '/' Tc=3.1 min CN=93 4.74 cfs Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 4HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-2E: Offsite to Southwest Runoff = 0.35 cfs @ 12.04 hrs, Volume= 0.020 af, Depth= 1.22" 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=2.80" Area (sf) CN Description 4,944 98 Paved parking, HSG B 3,705 61 >75% Grass cover, Good, HSG B 8,649 82 Weighted Average 3,705 42.84% Pervious Area 4,944 57.16% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.8 52 0.0190 1.11 Sheet Flow, Pavement Smooth surfaces n= 0.011 P2= 2.80" 10.5 115 0.0260 0.18 Sheet Flow, Grass Swale Grass: Short n= 0.150 P2= 2.80" 11.3 167 Total Subcatchment DA-2E: Offsite to Southwest Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type II 24-hr 2 Year Rainfall=2.80" Runoff Area=8,649 sf Runoff Volume=0.020 af Runoff Depth=1.22" Flow Length=167' Tc=11.3 min CN=82 0.35 cfs Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 5HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-3E: Offsite to East [49] Hint: Tc<2dt may require smaller dt Runoff = 0.01 cfs @ 11.97 hrs, Volume= 0.001 af, Depth= 0.29" 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=2.80" Area (sf) CN Description 962 61 >75% Grass cover, Good, HSG B 962 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.3 35 0.0430 0.18 Sheet Flow, Grass Grass: Short n= 0.150 P2= 2.80" Subcatchment DA-3E: Offsite to East Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)0.009 0.009 0.008 0.007 0.007 0.006 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Type II 24-hr 2 Year Rainfall=2.80" Runoff Area=962 sf Runoff Volume=0.001 af Runoff Depth=0.29" Flow Length=35' Slope=0.0430 '/' Tc=3.3 min CN=61 0.01 cfs Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 6HydroCAD® 10.10-4b s/n 02676 © 2020 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=55,435 sf 87.58% Impervious Runoff Depth=3.41"Subcatchment DA-1E: Offsite to North Flow Length=269' Slope=0.0170 '/' Tc=3.1 min CN=93 Runoff=7.58 cfs 0.362 af Runoff Area=8,649 sf 57.16% Impervious Runoff Depth=2.37"Subcatchment DA-2E: Offsite to Southwest Flow Length=167' Tc=11.3 min CN=82 Runoff=0.68 cfs 0.039 af Runoff Area=962 sf 0.00% Impervious Runoff Depth=0.92"Subcatchment DA-3E: Offsite to East Flow Length=35' Slope=0.0430 '/' Tc=3.3 min CN=61 Runoff=0.04 cfs 0.002 af Total Runoff Area = 1.493 ac Runoff Volume = 0.403 af Average Runoff Depth = 3.24" 17.76% Pervious = 0.265 ac 82.24% Impervious = 1.228 ac Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 7HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-1E: Offsite to North [49] Hint: Tc<2dt may require smaller dt Runoff = 7.58 cfs @ 11.93 hrs, Volume= 0.362 af, Depth= 3.41" 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=4.20" Area (sf) CN Description 48,550 98 Paved parking, HSG B 6,885 61 >75% Grass cover, Good, HSG B 55,435 93 Weighted Average 6,885 12.42% Pervious Area 48,550 87.58% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.1 269 0.0170 1.47 Sheet Flow, Pavement Smooth surfaces n= 0.011 P2= 2.80" Subcatchment DA-1E: Offsite to North Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)8 7 6 5 4 3 2 1 0 Type II 24-hr 10 Year Rainfall=4.20" Runoff Area=55,435 sf Runoff Volume=0.362 af Runoff Depth=3.41" Flow Length=269' Slope=0.0170 '/' Tc=3.1 min CN=93 7.58 cfs Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 8HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-2E: Offsite to Southwest Runoff = 0.68 cfs @ 12.03 hrs, Volume= 0.039 af, Depth= 2.37" 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=4.20" Area (sf) CN Description 4,944 98 Paved parking, HSG B 3,705 61 >75% Grass cover, Good, HSG B 8,649 82 Weighted Average 3,705 42.84% Pervious Area 4,944 57.16% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.8 52 0.0190 1.11 Sheet Flow, Pavement Smooth surfaces n= 0.011 P2= 2.80" 10.5 115 0.0260 0.18 Sheet Flow, Grass Swale Grass: Short n= 0.150 P2= 2.80" 11.3 167 Total Subcatchment DA-2E: Offsite to Southwest Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type II 24-hr 10 Year Rainfall=4.20" Runoff Area=8,649 sf Runoff Volume=0.039 af Runoff Depth=2.37" Flow Length=167' Tc=11.3 min CN=82 0.68 cfs Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 9HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-3E: Offsite to East [49] Hint: Tc<2dt may require smaller dt Runoff = 0.04 cfs @ 11.95 hrs, Volume= 0.002 af, Depth= 0.92" 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=4.20" Area (sf) CN Description 962 61 >75% Grass cover, Good, HSG B 962 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.3 35 0.0430 0.18 Sheet Flow, Grass Grass: Short n= 0.150 P2= 2.80" Subcatchment DA-3E: Offsite to East Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)0.04 0.038 0.036 0.034 0.032 0.03 0.028 0.026 0.024 0.022 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Type II 24-hr 10 Year Rainfall=4.20" Runoff Area=962 sf Runoff Volume=0.002 af Runoff Depth=0.92" Flow Length=35' Slope=0.0430 '/' Tc=3.3 min CN=61 0.04 cfs Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 10HydroCAD® 10.10-4b s/n 02676 © 2020 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=55,435 sf 87.58% Impervious Runoff Depth=6.47"Subcatchment DA-1E: Offsite to North Flow Length=269' Slope=0.0170 '/' Tc=3.1 min CN=93 Runoff=13.75 cfs 0.686 af Runoff Area=8,649 sf 57.16% Impervious Runoff Depth=5.20"Subcatchment DA-2E: Offsite to Southwest Flow Length=167' Tc=11.3 min CN=82 Runoff=1.45 cfs 0.086 af Runoff Area=962 sf 0.00% Impervious Runoff Depth=2.92"Subcatchment DA-3E: Offsite to East Flow Length=35' Slope=0.0430 '/' Tc=3.3 min CN=61 Runoff=0.12 cfs 0.005 af Total Runoff Area = 1.493 ac Runoff Volume = 0.777 af Average Runoff Depth = 6.25" 17.76% Pervious = 0.265 ac 82.24% Impervious = 1.228 ac Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 11HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-1E: Offsite to North [49] Hint: Tc<2dt may require smaller dt Runoff = 13.75 cfs @ 11.93 hrs, Volume= 0.686 af, Depth= 6.47" 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=7.30" Area (sf) CN Description 48,550 98 Paved parking, HSG B 6,885 61 >75% Grass cover, Good, HSG B 55,435 93 Weighted Average 6,885 12.42% Pervious Area 48,550 87.58% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.1 269 0.0170 1.47 Sheet Flow, Pavement Smooth surfaces n= 0.011 P2= 2.80" Subcatchment DA-1E: Offsite to North Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Type II 24-hr 100 Year Rainfall=7.30" Runoff Area=55,435 sf Runoff Volume=0.686 af Runoff Depth=6.47" Flow Length=269' Slope=0.0170 '/' Tc=3.1 min CN=93 13.75 cfs Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 12HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-2E: Offsite to Southwest Runoff = 1.45 cfs @ 12.03 hrs, Volume= 0.086 af, Depth= 5.20" 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=7.30" Area (sf) CN Description 4,944 98 Paved parking, HSG B 3,705 61 >75% Grass cover, Good, HSG B 8,649 82 Weighted Average 3,705 42.84% Pervious Area 4,944 57.16% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.8 52 0.0190 1.11 Sheet Flow, Pavement Smooth surfaces n= 0.011 P2= 2.80" 10.5 115 0.0260 0.18 Sheet Flow, Grass Swale Grass: Short n= 0.150 P2= 2.80" 11.3 167 Total Subcatchment DA-2E: Offsite to Southwest Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)1 0 Type II 24-hr 100 Year Rainfall=7.30" Runoff Area=8,649 sf Runoff Volume=0.086 af Runoff Depth=5.20" Flow Length=167' Tc=11.3 min CN=82 1.45 cfs Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 13HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-3E: Offsite to East [49] Hint: Tc<2dt may require smaller dt Runoff = 0.12 cfs @ 11.94 hrs, Volume= 0.005 af, Depth= 2.92" 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=7.30" Area (sf) CN Description 962 61 >75% Grass cover, Good, HSG B 962 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.3 35 0.0430 0.18 Sheet Flow, Grass Grass: Short n= 0.150 P2= 2.80" Subcatchment DA-3E: Offsite to East Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type II 24-hr 100 Year Rainfall=7.30" Runoff Area=962 sf Runoff Volume=0.005 af Runoff Depth=2.92" Flow Length=35' Slope=0.0430 '/' Tc=3.3 min CN=61 0.12 cfs Appendix B HydroCAD Report – Proposed Conditions – 2, 10 & 100 Year Events PROPOSED DA-1Pa Offsite North DA-1Pb To Infiltration Basin 1 DA-2P To Infiltration Basin 2 1B Infiltration Basin 1 2B Infiltration Basin 2 1L Total Offsite North Routing Diagram for 21210 - St. Croix Valley Park Dental Prepared by Loucks, Printed 9/14/2021 HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 2HydroCAD® 10.10-4b s/n 02676 © 2020 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=8,266 sf 92.12% Impervious Runoff Depth=2.25"Subcatchment DA-1Pa: Offsite North Tc=10.0 min CN=95 Runoff=0.61 cfs 0.036 af Runoff Area=44,520 sf 71.42% Impervious Runoff Depth=1.57"Subcatchment DA-1Pb: To Infiltration Tc=10.0 min CN=87 Runoff=2.42 cfs 0.133 af Runoff Area=12,260 sf 54.04% Impervious Runoff Depth=1.16"Subcatchment DA-2P: To Infiltration Basin Tc=10.0 min CN=81 Runoff=0.49 cfs 0.027 af Peak Elev=931.76' Storage=3,015 cf Inflow=2.42 cfs 0.133 afPond 1B: Infiltration Basin 1 Discarded=0.02 cfs 0.081 af Primary=0.25 cfs 0.052 af Outflow=0.27 cfs 0.132 af Peak Elev=935.15' Storage=732 cf Inflow=0.49 cfs 0.027 afPond 2B: Infiltration Basin 2 Discarded=0.01 cfs 0.027 af Primary=0.00 cfs 0.000 af Outflow=0.01 cfs 0.027 af Inflow=0.61 cfs 0.087 afLink 1L: Total Offsite North Primary=0.61 cfs 0.087 af Total Runoff Area = 1.493 ac Runoff Volume = 0.196 af Average Runoff Depth = 1.58" 29.23% Pervious = 0.436 ac 70.77% Impervious = 1.057 ac Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 3HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-1Pa: Offsite North Runoff = 0.61 cfs @ 12.01 hrs, Volume= 0.036 af, Depth= 2.25" 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=2.80" Area (sf) CN Description 7,615 98 Paved roads w/curbs & sewers, HSG B 651 61 >75% Grass cover, Good, HSG B 8,266 95 Weighted Average 651 7.88% Pervious Area 7,615 92.12% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment DA-1Pa: Offsite North Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type II 24-hr 2 Year Rainfall=2.80" Runoff Area=8,266 sf Runoff Volume=0.036 af Runoff Depth=2.25" Tc=10.0 min CN=95 0.61 cfs Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 4HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-1Pb: To Infiltration Basin 1 Runoff = 2.42 cfs @ 12.01 hrs, Volume= 0.133 af, Depth= 1.57" 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 2 Year Rainfall=2.80" Area (sf) CN Description 31,794 98 Paved parking, HSG B 12,726 61 >75% Grass cover, Good, HSG B 44,520 87 Weighted Average 12,726 28.58% Pervious Area 31,794 71.42% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment DA-1Pb: To Infiltration Basin 1 Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Type II 24-hr 2 Year Rainfall=2.80" Runoff Area=44,520 sf Runoff Volume=0.133 af Runoff Depth=1.57" Tc=10.0 min CN=87 2.42 cfs Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 5HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-2P: To Infiltration Basin 2 Runoff = 0.49 cfs @ 12.02 hrs, Volume= 0.027 af, Depth= 1.16" 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=2.80" Area (sf) CN Description 6,625 98 Paved parking, HSG B 5,635 61 >75% Grass cover, Good, HSG B 12,260 81 Weighted Average 5,635 45.96% Pervious Area 6,625 54.04% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment DA-2P: To Infiltration Basin 2 Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type II 24-hr 2 Year Rainfall=2.80" Runoff Area=12,260 sf Runoff Volume=0.027 af Runoff Depth=1.16" Tc=10.0 min CN=81 0.49 cfs Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 6HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1B: Infiltration Basin 1 Inflow Area = 1.022 ac, 71.42% Impervious, Inflow Depth = 1.57" for 2 Year event Inflow = 2.42 cfs @ 12.01 hrs, Volume= 0.133 af Outflow = 0.27 cfs @ 12.51 hrs, Volume= 0.132 af, Atten= 89%, Lag= 30.0 min Discarded = 0.02 cfs @ 12.51 hrs, Volume= 0.081 af Primary = 0.25 cfs @ 12.51 hrs, Volume= 0.052 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 931.76' @ 12.51 hrs Surf.Area= 1,957 sf Storage= 3,015 cf Plug-Flow detention time= 916.9 min calculated for 0.132 af (99% of inflow) Center-of-Mass det. time= 913.7 min ( 1,738.9 - 825.2 ) Volume Invert Avail.Storage Storage Description #1 929.70' 12,153 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) 929.70 901 256.0 0 0 901 930.00 1,134 263.0 305 305 1,200 931.00 1,592 279.0 1,357 1,661 1,942 931.50 1,834 288.0 856 2,517 2,372 935.00 3,789 351.0 9,636 12,153 5,765 Device Routing Invert Outlet Devices #1 Primary 931.50'12.0" Round Culvert L= 25.0' RCP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 931.50' / 931.30' S= 0.0080 '/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Primary 934.50'5.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #3 Discarded 929.70'0.450 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.02 cfs @ 12.51 hrs HW=931.76' (Free Discharge) 3=Exfiltration (Exfiltration Controls 0.02 cfs) Primary OutFlow Max=0.25 cfs @ 12.51 hrs HW=931.76' (Free Discharge) 1=Culvert (Barrel Controls 0.25 cfs @ 2.28 fps) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 7HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Pond 1B: Infiltration Basin 1 Inflow Outflow Discarded Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Inflow Area=1.022 ac Peak Elev=931.76' Storage=3,015 cf 2.42 cfs 0.27 cfs 0.02 cfs0.25 cfs Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 8HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 1B: Infiltration Basin 1 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 929.70 901 0 929.80 976 94 929.90 1,053 195 930.00 1,134 305 930.10 1,176 420 930.20 1,219 540 930.30 1,263 664 930.40 1,308 793 930.50 1,353 926 930.60 1,399 1,063 930.70 1,446 1,206 930.80 1,494 1,353 930.90 1,543 1,504 931.00 1,592 1,661 931.10 1,639 1,823 931.20 1,687 1,989 931.30 1,735 2,160 931.40 1,784 2,336 931.50 1,834 2,517 931.60 1,880 2,703 931.70 1,927 2,893 931.80 1,974 3,088 931.90 2,022 3,288 932.00 2,070 3,492 932.10 2,119 3,702 932.20 2,169 3,916 932.30 2,219 4,136 932.40 2,270 4,360 932.50 2,321 4,590 932.60 2,373 4,824 932.70 2,425 5,064 932.80 2,478 5,309 932.90 2,532 5,560 933.00 2,586 5,816 933.10 2,641 6,077 933.20 2,696 6,344 933.30 2,752 6,616 933.40 2,808 6,894 933.50 2,865 7,178 933.60 2,923 7,467 933.70 2,981 7,763 933.80 3,040 8,064 933.90 3,099 8,370 934.00 3,159 8,683 934.10 3,219 9,002 934.20 3,280 9,327 934.30 3,342 9,658 934.40 3,404 9,996 934.50 3,467 10,339 934.60 3,530 10,689 934.70 3,594 11,045 934.80 3,658 11,408 934.90 3,723 11,777 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 935.00 3,789 12,153 Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 9HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Pond 2B: Infiltration Basin 2 Inflow Area = 0.281 ac, 54.04% Impervious, Inflow Depth = 1.16" for 2 Year event Inflow = 0.49 cfs @ 12.02 hrs, Volume= 0.027 af Outflow = 0.01 cfs @ 16.06 hrs, Volume= 0.027 af, Atten= 97%, Lag= 242.1 min Discarded = 0.01 cfs @ 16.06 hrs, Volume= 0.027 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 935.15' @ 16.06 hrs Surf.Area= 1,279 sf Storage= 732 cf Plug-Flow detention time= 721.5 min calculated for 0.027 af (100% of inflow) Center-of-Mass det. time= 722.2 min ( 1,569.1 - 846.8 ) Volume Invert Avail.Storage Storage Description #1 934.00' 3,540 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) 934.00 139 139.0 0 0 139 935.00 1,127 379.0 554 554 10,035 935.80 2,057 396.0 1,255 1,809 11,129 936.00 2,295 400.0 435 2,244 11,394 936.50 2,902 410.0 1,296 3,540 12,070 Device Routing Invert Outlet Devices #1 Primary 935.80'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #2 Discarded 934.00'0.450 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.01 cfs @ 16.06 hrs HW=935.15' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=934.00' (Free Discharge) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 10HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Pond 2B: Infiltration Basin 2 Inflow Outflow Discarded Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.281 ac Peak Elev=935.15' Storage=732 cf 0.49 cfs 0.01 cfs0.01 cfs 0.00 cfs Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 11HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 2B: Infiltration Basin 2 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 934.00 139 0 934.05 166 8 934.10 195 17 934.15 227 27 934.20 261 39 934.25 297 53 934.30 336 69 934.35 377 87 934.40 420 107 934.45 466 129 934.50 514 153 934.55 565 180 934.60 618 210 934.65 673 242 934.70 731 277 934.75 791 315 934.80 853 357 934.85 918 401 934.90 986 448 934.95 1,055 499 935.00 1,127 554 935.05 1,177 612 935.10 1,228 672 935.15 1,280 734 935.20 1,333 800 935.25 1,388 868 935.30 1,443 938 935.35 1,500 1,012 935.40 1,557 1,088 935.45 1,616 1,168 935.50 1,676 1,250 935.55 1,737 1,335 935.60 1,798 1,424 935.65 1,861 1,515 935.70 1,926 1,610 935.75 1,991 1,708 935.80 2,057 1,809 935.85 2,115 1,913 935.90 2,174 2,021 935.95 2,234 2,131 936.00 2,295 2,244 936.05 2,352 2,360 936.10 2,411 2,479 936.15 2,470 2,601 936.20 2,529 2,726 936.25 2,590 2,854 936.30 2,651 2,985 936.35 2,712 3,119 936.40 2,775 3,256 936.45 2,838 3,397 936.50 2,902 3,540 Type II 24-hr 2 Year Rainfall=2.80"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 12HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Total Offsite North Inflow Area = 1.212 ac, 74.66% Impervious, Inflow Depth = 0.86" for 2 Year event Inflow = 0.61 cfs @ 12.01 hrs, Volume= 0.087 af Primary = 0.61 cfs @ 12.01 hrs, Volume= 0.087 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Link 1L: Total Offsite North Inflow Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=1.212 ac 0.61 cfs0.61 cfs Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 13HydroCAD® 10.10-4b s/n 02676 © 2020 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=8,266 sf 92.12% Impervious Runoff Depth=3.63"Subcatchment DA-1Pa: Offsite North Tc=10.0 min CN=95 Runoff=0.95 cfs 0.057 af Runoff Area=44,520 sf 71.42% Impervious Runoff Depth=2.82"Subcatchment DA-1Pb: To Infiltration Tc=10.0 min CN=87 Runoff=4.28 cfs 0.240 af Runoff Area=12,260 sf 54.04% Impervious Runoff Depth=2.29"Subcatchment DA-2P: To Infiltration Basin Tc=10.0 min CN=81 Runoff=0.97 cfs 0.054 af Peak Elev=932.39' Storage=4,326 cf Inflow=4.28 cfs 0.240 afPond 1B: Infiltration Basin 1 Discarded=0.02 cfs 0.084 af Primary=2.02 cfs 0.155 af Outflow=2.04 cfs 0.239 af Peak Elev=935.69' Storage=1,593 cf Inflow=0.97 cfs 0.054 afPond 2B: Infiltration Basin 2 Discarded=0.02 cfs 0.054 af Primary=0.00 cfs 0.000 af Outflow=0.02 cfs 0.054 af Inflow=2.54 cfs 0.213 afLink 1L: Total Offsite North Primary=2.54 cfs 0.213 af Total Runoff Area = 1.493 ac Runoff Volume = 0.351 af Average Runoff Depth = 2.82" 29.23% Pervious = 0.436 ac 70.77% Impervious = 1.057 ac Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 14HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-1Pa: Offsite North Runoff = 0.95 cfs @ 12.01 hrs, Volume= 0.057 af, Depth= 3.63" 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=4.20" Area (sf) CN Description 7,615 98 Paved roads w/curbs & sewers, HSG B 651 61 >75% Grass cover, Good, HSG B 8,266 95 Weighted Average 651 7.88% Pervious Area 7,615 92.12% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment DA-1Pa: Offsite North Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)1 0 Type II 24-hr 10 Year Rainfall=4.20" Runoff Area=8,266 sf Runoff Volume=0.057 af Runoff Depth=3.63" Tc=10.0 min CN=95 0.95 cfs Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 15HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-1Pb: To Infiltration Basin 1 Runoff = 4.28 cfs @ 12.01 hrs, Volume= 0.240 af, Depth= 2.82" 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=4.20" Area (sf) CN Description 31,794 98 Paved parking, HSG B 12,726 61 >75% Grass cover, Good, HSG B 44,520 87 Weighted Average 12,726 28.58% Pervious Area 31,794 71.42% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment DA-1Pb: To Infiltration Basin 1 Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Type II 24-hr 10 Year Rainfall=4.20" Runoff Area=44,520 sf Runoff Volume=0.240 af Runoff Depth=2.82" Tc=10.0 min CN=87 4.28 cfs Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 16HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-2P: To Infiltration Basin 2 Runoff = 0.97 cfs @ 12.02 hrs, Volume= 0.054 af, Depth= 2.29" 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=4.20" Area (sf) CN Description 6,625 98 Paved parking, HSG B 5,635 61 >75% Grass cover, Good, HSG B 12,260 81 Weighted Average 5,635 45.96% Pervious Area 6,625 54.04% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment DA-2P: To Infiltration Basin 2 Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)1 0 Type II 24-hr 10 Year Rainfall=4.20" Runoff Area=12,260 sf Runoff Volume=0.054 af Runoff Depth=2.29" Tc=10.0 min CN=81 0.97 cfs Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 17HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1B: Infiltration Basin 1 Inflow Area = 1.022 ac, 71.42% Impervious, Inflow Depth = 2.82" for 10 Year event Inflow = 4.28 cfs @ 12.01 hrs, Volume= 0.240 af Outflow = 2.04 cfs @ 12.15 hrs, Volume= 0.239 af, Atten= 52%, Lag= 8.2 min Discarded = 0.02 cfs @ 12.15 hrs, Volume= 0.084 af Primary = 2.02 cfs @ 12.15 hrs, Volume= 0.155 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 932.39' @ 12.15 hrs Surf.Area= 2,262 sf Storage= 4,326 cf Plug-Flow detention time= 527.6 min calculated for 0.239 af (99% of inflow) Center-of-Mass det. time= 524.1 min ( 1,332.6 - 808.5 ) Volume Invert Avail.Storage Storage Description #1 929.70' 12,153 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) 929.70 901 256.0 0 0 901 930.00 1,134 263.0 305 305 1,200 931.00 1,592 279.0 1,357 1,661 1,942 931.50 1,834 288.0 856 2,517 2,372 935.00 3,789 351.0 9,636 12,153 5,765 Device Routing Invert Outlet Devices #1 Primary 931.50'12.0" Round Culvert L= 25.0' RCP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 931.50' / 931.30' S= 0.0080 '/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Primary 934.50'5.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #3 Discarded 929.70'0.450 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.02 cfs @ 12.15 hrs HW=932.38' (Free Discharge) 3=Exfiltration (Exfiltration Controls 0.02 cfs) Primary OutFlow Max=2.01 cfs @ 12.15 hrs HW=932.38' (Free Discharge) 1=Culvert (Barrel Controls 2.01 cfs @ 3.64 fps) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 18HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Pond 1B: Infiltration Basin 1 Inflow Outflow Discarded Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)4 3 2 1 0 Inflow Area=1.022 ac Peak Elev=932.39' Storage=4,326 cf 4.28 cfs 2.04 cfs 0.02 cfs 2.02 cfs Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 19HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 1B: Infiltration Basin 1 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 929.70 901 0 929.80 976 94 929.90 1,053 195 930.00 1,134 305 930.10 1,176 420 930.20 1,219 540 930.30 1,263 664 930.40 1,308 793 930.50 1,353 926 930.60 1,399 1,063 930.70 1,446 1,206 930.80 1,494 1,353 930.90 1,543 1,504 931.00 1,592 1,661 931.10 1,639 1,823 931.20 1,687 1,989 931.30 1,735 2,160 931.40 1,784 2,336 931.50 1,834 2,517 931.60 1,880 2,703 931.70 1,927 2,893 931.80 1,974 3,088 931.90 2,022 3,288 932.00 2,070 3,492 932.10 2,119 3,702 932.20 2,169 3,916 932.30 2,219 4,136 932.40 2,270 4,360 932.50 2,321 4,590 932.60 2,373 4,824 932.70 2,425 5,064 932.80 2,478 5,309 932.90 2,532 5,560 933.00 2,586 5,816 933.10 2,641 6,077 933.20 2,696 6,344 933.30 2,752 6,616 933.40 2,808 6,894 933.50 2,865 7,178 933.60 2,923 7,467 933.70 2,981 7,763 933.80 3,040 8,064 933.90 3,099 8,370 934.00 3,159 8,683 934.10 3,219 9,002 934.20 3,280 9,327 934.30 3,342 9,658 934.40 3,404 9,996 934.50 3,467 10,339 934.60 3,530 10,689 934.70 3,594 11,045 934.80 3,658 11,408 934.90 3,723 11,777 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 935.00 3,789 12,153 Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 20HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Pond 2B: Infiltration Basin 2 Inflow Area = 0.281 ac, 54.04% Impervious, Inflow Depth = 2.29" for 10 Year event Inflow = 0.97 cfs @ 12.02 hrs, Volume= 0.054 af Outflow = 0.02 cfs @ 17.29 hrs, Volume= 0.054 af, Atten= 98%, Lag= 316.2 min Discarded = 0.02 cfs @ 17.29 hrs, Volume= 0.054 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 935.69' @ 17.29 hrs Surf.Area= 1,914 sf Storage= 1,593 cf Plug-Flow detention time= 1,019.2 min calculated for 0.054 af (100% of inflow) Center-of-Mass det. time= 1,019.1 min ( 1,846.3 - 827.2 ) Volume Invert Avail.Storage Storage Description #1 934.00' 3,540 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) 934.00 139 139.0 0 0 139 935.00 1,127 379.0 554 554 10,035 935.80 2,057 396.0 1,255 1,809 11,129 936.00 2,295 400.0 435 2,244 11,394 936.50 2,902 410.0 1,296 3,540 12,070 Device Routing Invert Outlet Devices #1 Primary 935.80'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #2 Discarded 934.00'0.450 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.02 cfs @ 17.29 hrs HW=935.69' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.02 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=934.00' (Free Discharge) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 21HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Pond 2B: Infiltration Basin 2 Inflow Outflow Discarded Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)1 0 Inflow Area=0.281 ac Peak Elev=935.69' Storage=1,593 cf 0.97 cfs 0.02 cfs0.02 cfs 0.00 cfs Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 22HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 2B: Infiltration Basin 2 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 934.00 139 0 934.05 166 8 934.10 195 17 934.15 227 27 934.20 261 39 934.25 297 53 934.30 336 69 934.35 377 87 934.40 420 107 934.45 466 129 934.50 514 153 934.55 565 180 934.60 618 210 934.65 673 242 934.70 731 277 934.75 791 315 934.80 853 357 934.85 918 401 934.90 986 448 934.95 1,055 499 935.00 1,127 554 935.05 1,177 612 935.10 1,228 672 935.15 1,280 734 935.20 1,333 800 935.25 1,388 868 935.30 1,443 938 935.35 1,500 1,012 935.40 1,557 1,088 935.45 1,616 1,168 935.50 1,676 1,250 935.55 1,737 1,335 935.60 1,798 1,424 935.65 1,861 1,515 935.70 1,926 1,610 935.75 1,991 1,708 935.80 2,057 1,809 935.85 2,115 1,913 935.90 2,174 2,021 935.95 2,234 2,131 936.00 2,295 2,244 936.05 2,352 2,360 936.10 2,411 2,479 936.15 2,470 2,601 936.20 2,529 2,726 936.25 2,590 2,854 936.30 2,651 2,985 936.35 2,712 3,119 936.40 2,775 3,256 936.45 2,838 3,397 936.50 2,902 3,540 Type II 24-hr 10 Year Rainfall=4.20"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 23HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Total Offsite North Inflow Area = 1.212 ac, 74.66% Impervious, Inflow Depth = 2.11" for 10 Year event Inflow = 2.54 cfs @ 12.11 hrs, Volume= 0.213 af Primary = 2.54 cfs @ 12.11 hrs, Volume= 0.213 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Link 1L: Total Offsite North Inflow Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Inflow Area=1.212 ac 2.54 cfs2.54 cfs Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 24HydroCAD® 10.10-4b s/n 02676 © 2020 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=8,266 sf 92.12% Impervious Runoff Depth=6.70"Subcatchment DA-1Pa: Offsite North Tc=10.0 min CN=95 Runoff=1.70 cfs 0.106 af Runoff Area=44,520 sf 71.42% Impervious Runoff Depth=5.77"Subcatchment DA-1Pb: To Infiltration Tc=10.0 min CN=87 Runoff=8.43 cfs 0.491 af Runoff Area=12,260 sf 54.04% Impervious Runoff Depth=5.08"Subcatchment DA-2P: To Infiltration Basin Tc=10.0 min CN=81 Runoff=2.11 cfs 0.119 af Peak Elev=933.49' Storage=7,152 cf Inflow=8.43 cfs 0.491 afPond 1B: Infiltration Basin 1 Discarded=0.03 cfs 0.088 af Primary=4.62 cfs 0.402 af Outflow=4.65 cfs 0.490 af Peak Elev=935.96' Storage=2,145 cf Inflow=2.11 cfs 0.119 afPond 2B: Infiltration Basin 2 Discarded=0.02 cfs 0.066 af Primary=1.44 cfs 0.054 af Outflow=1.47 cfs 0.119 af Inflow=5.92 cfs 0.508 afLink 1L: Total Offsite North Primary=5.92 cfs 0.508 af Total Runoff Area = 1.493 ac Runoff Volume = 0.717 af Average Runoff Depth = 5.76" 29.23% Pervious = 0.436 ac 70.77% Impervious = 1.057 ac Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 25HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-1Pa: Offsite North Runoff = 1.70 cfs @ 12.01 hrs, Volume= 0.106 af, Depth= 6.70" 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=7.30" Area (sf) CN Description 7,615 98 Paved roads w/curbs & sewers, HSG B 651 61 >75% Grass cover, Good, HSG B 8,266 95 Weighted Average 651 7.88% Pervious Area 7,615 92.12% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment DA-1Pa: Offsite North Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)1 0 Type II 24-hr 100 Year Rainfall=7.30" Runoff Area=8,266 sf Runoff Volume=0.106 af Runoff Depth=6.70" Tc=10.0 min CN=95 1.70 cfs Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 26HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-1Pb: To Infiltration Basin 1 Runoff = 8.43 cfs @ 12.01 hrs, Volume= 0.491 af, Depth= 5.77" 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=7.30" Area (sf) CN Description 31,794 98 Paved parking, HSG B 12,726 61 >75% Grass cover, Good, HSG B 44,520 87 Weighted Average 12,726 28.58% Pervious Area 31,794 71.42% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment DA-1Pb: To Infiltration Basin 1 Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)9 8 7 6 5 4 3 2 1 0 Type II 24-hr 100 Year Rainfall=7.30" Runoff Area=44,520 sf Runoff Volume=0.491 af Runoff Depth=5.77" Tc=10.0 min CN=87 8.43 cfs Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 27HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Subcatchment DA-2P: To Infiltration Basin 2 Runoff = 2.11 cfs @ 12.01 hrs, Volume= 0.119 af, Depth= 5.08" 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=7.30" Area (sf) CN Description 6,625 98 Paved parking, HSG B 5,635 61 >75% Grass cover, Good, HSG B 12,260 81 Weighted Average 5,635 45.96% Pervious Area 6,625 54.04% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Subcatchment DA-2P: To Infiltration Basin 2 Runoff Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Type II 24-hr 100 Year Rainfall=7.30" Runoff Area=12,260 sf Runoff Volume=0.119 af Runoff Depth=5.08" Tc=10.0 min CN=81 2.11 cfs Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 28HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Pond 1B: Infiltration Basin 1 Inflow Area = 1.022 ac, 71.42% Impervious, Inflow Depth = 5.77" for 100 Year event Inflow = 8.43 cfs @ 12.01 hrs, Volume= 0.491 af Outflow = 4.65 cfs @ 12.12 hrs, Volume= 0.490 af, Atten= 45%, Lag= 6.9 min Discarded = 0.03 cfs @ 12.12 hrs, Volume= 0.088 af Primary = 4.62 cfs @ 12.12 hrs, Volume= 0.402 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 933.49' @ 12.12 hrs Surf.Area= 2,860 sf Storage= 7,152 cf Plug-Flow detention time= 279.7 min calculated for 0.490 af (100% of inflow) Center-of-Mass det. time= 277.5 min ( 1,065.9 - 788.4 ) Volume Invert Avail.Storage Storage Description #1 929.70' 12,153 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) 929.70 901 256.0 0 0 901 930.00 1,134 263.0 305 305 1,200 931.00 1,592 279.0 1,357 1,661 1,942 931.50 1,834 288.0 856 2,517 2,372 935.00 3,789 351.0 9,636 12,153 5,765 Device Routing Invert Outlet Devices #1 Primary 931.50'12.0" Round Culvert L= 25.0' RCP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 931.50' / 931.30' S= 0.0080 '/' Cc= 0.900 n= 0.012 Concrete pipe, finished, Flow Area= 0.79 sf #2 Primary 934.50'5.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #3 Discarded 929.70'0.450 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.03 cfs @ 12.12 hrs HW=933.47' (Free Discharge) 3=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=4.59 cfs @ 12.12 hrs HW=933.47' (Free Discharge) 1=Culvert (Inlet Controls 4.59 cfs @ 5.84 fps) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 29HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Pond 1B: Infiltration Basin 1 Inflow Outflow Discarded Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)9 8 7 6 5 4 3 2 1 0 Inflow Area=1.022 ac Peak Elev=933.49' Storage=7,152 cf 8.43 cfs 4.65 cfs 0.03 cfs 4.62 cfs Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 30HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 1B: Infiltration Basin 1 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 929.70 901 0 929.80 976 94 929.90 1,053 195 930.00 1,134 305 930.10 1,176 420 930.20 1,219 540 930.30 1,263 664 930.40 1,308 793 930.50 1,353 926 930.60 1,399 1,063 930.70 1,446 1,206 930.80 1,494 1,353 930.90 1,543 1,504 931.00 1,592 1,661 931.10 1,639 1,823 931.20 1,687 1,989 931.30 1,735 2,160 931.40 1,784 2,336 931.50 1,834 2,517 931.60 1,880 2,703 931.70 1,927 2,893 931.80 1,974 3,088 931.90 2,022 3,288 932.00 2,070 3,492 932.10 2,119 3,702 932.20 2,169 3,916 932.30 2,219 4,136 932.40 2,270 4,360 932.50 2,321 4,590 932.60 2,373 4,824 932.70 2,425 5,064 932.80 2,478 5,309 932.90 2,532 5,560 933.00 2,586 5,816 933.10 2,641 6,077 933.20 2,696 6,344 933.30 2,752 6,616 933.40 2,808 6,894 933.50 2,865 7,178 933.60 2,923 7,467 933.70 2,981 7,763 933.80 3,040 8,064 933.90 3,099 8,370 934.00 3,159 8,683 934.10 3,219 9,002 934.20 3,280 9,327 934.30 3,342 9,658 934.40 3,404 9,996 934.50 3,467 10,339 934.60 3,530 10,689 934.70 3,594 11,045 934.80 3,658 11,408 934.90 3,723 11,777 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 935.00 3,789 12,153 Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 31HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Pond 2B: Infiltration Basin 2 Inflow Area = 0.281 ac, 54.04% Impervious, Inflow Depth = 5.08" for 100 Year event Inflow = 2.11 cfs @ 12.01 hrs, Volume= 0.119 af Outflow = 1.47 cfs @ 12.11 hrs, Volume= 0.119 af, Atten= 30%, Lag= 6.0 min Discarded = 0.02 cfs @ 12.11 hrs, Volume= 0.066 af Primary = 1.44 cfs @ 12.11 hrs, Volume= 0.054 af Routing by Stor-Ind method, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Peak Elev= 935.96' @ 12.11 hrs Surf.Area= 2,242 sf Storage= 2,145 cf Plug-Flow detention time= 602.9 min calculated for 0.119 af (100% of inflow) Center-of-Mass det. time= 604.3 min ( 1,408.9 - 804.5 ) Volume Invert Avail.Storage Storage Description #1 934.00' 3,540 cf Custom Stage Data (Irregular) Listed below (Recalc) Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area (feet) (sq-ft) (feet) (cubic-feet) (cubic-feet) (sq-ft) 934.00 139 139.0 0 0 139 935.00 1,127 379.0 554 554 10,035 935.80 2,057 396.0 1,255 1,809 11,129 936.00 2,295 400.0 435 2,244 11,394 936.50 2,902 410.0 1,296 3,540 12,070 Device Routing Invert Outlet Devices #1 Primary 935.80'10.0' long x 5.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #2 Discarded 934.00'0.450 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.02 cfs @ 12.11 hrs HW=935.95' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.02 cfs) Primary OutFlow Max=1.38 cfs @ 12.11 hrs HW=935.95' (Free Discharge) 1=Broad-Crested Rectangular Weir (Weir Controls 1.38 cfs @ 0.91 fps) Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 32HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Pond 2B: Infiltration Basin 2 Inflow Outflow Discarded Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)2 1 0 Inflow Area=0.281 ac Peak Elev=935.96' Storage=2,145 cf 2.11 cfs 1.47 cfs 0.02 cfs 1.44 cfs Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 33HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 2B: Infiltration Basin 2 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 934.00 139 0 934.05 166 8 934.10 195 17 934.15 227 27 934.20 261 39 934.25 297 53 934.30 336 69 934.35 377 87 934.40 420 107 934.45 466 129 934.50 514 153 934.55 565 180 934.60 618 210 934.65 673 242 934.70 731 277 934.75 791 315 934.80 853 357 934.85 918 401 934.90 986 448 934.95 1,055 499 935.00 1,127 554 935.05 1,177 612 935.10 1,228 672 935.15 1,280 734 935.20 1,333 800 935.25 1,388 868 935.30 1,443 938 935.35 1,500 1,012 935.40 1,557 1,088 935.45 1,616 1,168 935.50 1,676 1,250 935.55 1,737 1,335 935.60 1,798 1,424 935.65 1,861 1,515 935.70 1,926 1,610 935.75 1,991 1,708 935.80 2,057 1,809 935.85 2,115 1,913 935.90 2,174 2,021 935.95 2,234 2,131 936.00 2,295 2,244 936.05 2,352 2,360 936.10 2,411 2,479 936.15 2,470 2,601 936.20 2,529 2,726 936.25 2,590 2,854 936.30 2,651 2,985 936.35 2,712 3,119 936.40 2,775 3,256 936.45 2,838 3,397 936.50 2,902 3,540 Type II 24-hr 100 Year Rainfall=7.30"21210 - St. Croix Valley Park Dental Printed 9/14/2021Prepared by Loucks Page 34HydroCAD® 10.10-4b s/n 02676 © 2020 HydroCAD Software Solutions LLC Summary for Link 1L: Total Offsite North Inflow Area = 1.212 ac, 74.66% Impervious, Inflow Depth = 5.03" for 100 Year event Inflow = 5.92 cfs @ 12.06 hrs, Volume= 0.508 af Primary = 5.92 cfs @ 12.06 hrs, Volume= 0.508 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-72.00 hrs, dt= 0.05 hrs Link 1L: Total Offsite North Inflow Primary Hydrograph Time (hours) 727068666462605856545250484644424038363432302826242220181614121086420Flow (cfs)6 5 4 3 2 1 0 Inflow Area=1.212 ac 5.92 cfs5.92 cfs Appendix C Storm Sewer Pipe Sizing Storm Sewer Design CalculationsStorm Frequency: 10Assumed Value: n = 0.012*Up-CB Total CB Pipe Pipe Hyd. Hyd. Pipe Q Upstream DenotesStreamLen.CB Site C CA CA CB Indv. Total I I Q Dia. Grade Grade Grade Vel. Cap. Excess Structure HGLStruct.FtIndv. Indv. Indv. Tot. Tc Tp Tc In/Hr In/Hr CFS In. % % Elev. Ft/S CFS CFS Rim Elev. > Rim CommentsCB 104 62 0.23 0.23 0.90 0.21 0.21 10.0 0.3 10.3 5.6 5.6 1.2 12 0.44 0.11 933.51 3.3 2.6 1.3 936.20CBMH 103 92 0.21 0.44 0.90 0.19 0.39 10.0 0.5 10.5 5.6 5.6 1.0 12 0.44 0.36 933.45 3.3 2.6 0.3 936.20CBMH 102 96 0.25 0.69 0.90 0.23 0.62 10.0 0.5 10.5 5.6 5.6 1.3 15 0.32 0.26 933.12 3.2 4.0 0.4 936.10CBMH 101 36 0.06 0.75 0.90 0.06 0.68 10.0 0.2 10.2 5.6 5.6 0.3 15 0.32 0.31 932.86 3.2 4.0 0.1 934.37932.75 FES Outlet2.3CBMH 1031.3CFS Areas (ac.)StreamPark Dental St. Croix Valley21210Oak Park Heights, MNZHW9/14/212021/21210/Hydrology- Denotes HGL > Rim Elev.Revised:QFile: Revised:Date:Revised:Contract Mgr:Project No.: Location: FES 1003.9CBMH 1013.6CBMH 102TotalStruct.Down- Appendix D Geotechnical Exploration Report