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Stormwater Report 062519
Storm water Project Narrative Life Time – Healthy Way of Life 2970 Water Tower Place Parking Lot Addition June 24, 2019 Life Time is proposing an approximately 69,850 square foot parking lot expansion at their site located at 2970 Water Tower Place located in Chanhassen, Minnesota. The project includes associated storm water modifications to accommodate the parking lot expansion. The total disturbance area of the project is 92,700 square feet, with an area of impervious surface that is either created or disturbed of 71,645 square feet. Life Time is also proposing to expand the parking surface of their complex to the north of 2970 Water Tower Place. They are proposing to add parking on the north and south side of the existing properties located at 2901 Corporate Place, 2902 Corporate Place, and 2900 Corporate Place. The drive aisles would remain the same and head-in parking would be added. The existing surface consists of grass and landscaping on a 4:1 slope. The surface would be flattened to allow for a 5% parking surface and the soil would be retained with a wall. The proposed impervious surface to be added is 16,438 square feet. The project is located within the City of Chanhassen and the Riley Purgatory Bluff Creek Watershed District. The disturbance area is also of sufficient size to require a NPDES permit. The plans detail the work to be completed. The Watershed has two rules that the proposed work will trigger. The following summarizes those rules: Rule C: Erosion and Sediment Control Rule C: Erosion and Sediment Control of the Watershed is triggered by the excavation volume and disturbance area required for the parking lot construction and parking stall expansion. The erosion control and sediment plan sheet details the erosion control measures to be used on the site, which include silt fence, bio-logs, a construction entrance, and inlet protection. Biologs will be installed at the perimeter of the disturbance limits where the surface is pavement. Rule J: Stormwater Management Rule J: Stormwater Management of the Watershed is also triggered. The requirements apply to the disturbed and newly created impervious surface of 71,645 square feet for the alpha field and 16,438 square feet of impervious at the complex off of Corporate Place. The following criteria are required to be met as part of the project: 1. The peak runoff rates must be limited to existing conditions for the two, ten, and hundred year storm events using Atlas 14 rainfall data. All of the project area discharges to an existing storm sewer system and the drainage area will remain unchanged. In the proposed conditions an underground system is proposed for rate and treatment measures on the property located at 2970 Water Tower Place. Soil borings have been taken that indicate the on-site soils are sandy lean clay (CL), which are classified as hydrologic ground D. Curve numbers in the HydroCAD report reflect the D soils on- site. A HydroCad model indicates the following results for rate control: HyrdroCAD Results Storm Event Existing Rate (cfs) 2970 Water Tower Place Proposed Rate (cfs) 2970 Water Tower Place 2-Year 3.81 0.96 10-Year 7.04 3.37 100-Year 13.47 11.43 10 Day Snow Melt 0.59 0.40 Storm Event Existing Rate (cfs) Life Time Complex Proposed Rate (cfs) 2970 Water Tower Place 2-Year 77.74 77.74 10-Year 126.35 126.35 100-Year 212.09 212.09 10 Day Snow Melt 4.37 4.37 As noted above the proposed rate of runoff is less than existing for the required storm events. The complex was modeled as one overall site given the one exit point from the three sites at Corporate Place. The additional parking stall impervious surface is minor given the size of the site and does not have an impact on the discharge rates. 2. The project must provide for the abstraction on-site of 1.1 inches of runoff from the impervious surface. The area of impervious surface disturbed to native soils or created as part of the project is 71,645 square feet with an additional 16,438 from the complex area. Soil borings have been taken on the site as part of previous projects and on Life Time’s properties to the north. Braun’s geotechnical evaluation report dated July 3, 2013 indicates that the soils on the site consist of fill and sandy lean clay (CL). These soils are classified as hydrologic soil group D with an anticipated infiltration rate of 0.06 inches/hour as per the Minnesota Stormwater Manual. In addition, American Engineering Testing, Inc. provided a letter on January 17, 2017 specifically related to stormwater infiltration rates for the property directly to the north of the proposed parking lot addition. The soil types in this letter were also identified to have an infiltration rate of 0.06 in/hour and further stated that infiltration was not feasible. An e-mail from the Geotechnical Engineer is also attached to this report indicating that they would recommend an infiltration rate closer to 0.006 in/hour. Based on the soil boring information in general infiltration is not practical given the site conditions. The NPDES storm water permit also states that infiltration is prohibited in areas of predominately hydrologic soil group type D soils. Life Time reviewed different options to meet the infiltration requirement on a restricted site. The green space within the area has significant slopes and mature vegetation with clay soils and so utilizing that area for irrigation or reuse of some type is not feasible. The majority of the site is impervious surface that is not irrigated. Given the volume that is required to be infiltrated rain barrels are also not a feasible solution. As a result, biofiltration is proposed. The total area required to be treated under this scenario is: 1.1” x 1’/12” x 88,083 sf = 8,075 cf All of the properties where improvements are proposed ultimately discharge to the existing storm sewer system in Century Boulevard. In an effort to minimize additional pavement disturbance Life Time is proposing to complete the required filtration for all of the created or newly disturbed pavement within the underground system at 2970 Water Tower Place. This will require a request for a variance under Rule K. The variance is being requested to provide bio- filtration of an area equal to the impervious surface created on the Corporate Place proprieties by redirecting a portion of the existing parking lot to the east of 2970 Water Tower Place. The area of biofiltration provided in the underground system is noted in HydroCAD as the storage area below the outlet pipe at 997.05, which is 8,110 cf. This volume will be filtered through a one-foot sand section. The variance being requested is the ability to not treat all of the impervious surface directly at the site, but to combine the treatment into one large system. The required volume will still be provided and there will be no adverse effects downstream as all of the storm water runoff eventually reaches the same discharge location. One large practice will be more efficient and easier to maintain than three or four separate systems. It will also minimize disturbance during construction as additional pavement removal would be necessary. 3. The project must provide for at least sixty percent annual removal efficiency of phosphorus and at least ninety percent annual removal efficiency for total suspended solids from the site runoff. This is proposed to be achieved within the underground system. P8 was utilized to model the removal efficiency of the system. Below are the results from the model. Variable OVERALL StormTech Infiltration Area Draintile P0% 71.6 47.7 50.0 P10% 98.1 98.1 P30% 99.7 99.7 P50% 100.0 100.0 P80% 100.0 100.0 TSS 99.5 99.5 TP 91.4 84.6 50.0 TKN 88.7 79.6 50.0 CU 92.0 85.6 50.0 PB 96.9 94.7 50.0 ZN 75.5 54.9 50.0 HC 96.9 94.7 50.0 Low Floor No structure may be constructed such that its lowest floor elevation is less than 2-feet above the 100- year event flood elevation and no stormwater management system may be constructed or reconstructed in a manner that brings the low floor elevation of an adjacent structure into noncompliance. The existing building has a finished floor elevation of 1004.57. The 100-year peak elevation of the storm tech system is 999.40. DWSMA & ERA The site is not within an Emergency Response Area and Drinking Water Supply Management Area as indicated on the attached map from the Minnesota Pollution Control Agency. Summary Based on the constraints of the existing soil conditions standard infiltration practices are not practical to meet the required Watershed requirements. Therefore, the site is being proposed with an underground stormwater facility that will provide the required treatment over the same volume. Rate control is also managed through the facility. HydroCAD and P8 model results have been provided to document that the necessary requirements are being met. Stormwater Mapping Tool - MS4 Program Minnesota Pollution Control Agency, Esri, HERE, Garmin, (c) Emergency Response Areas Drinking Water Source Contamination Vulnerability Very High High Moderate Low Very Low MS4 - MNDOT MS4 - County MS4 - Watershed District MS4 - City or Township MS4 - Non-traditional 6/22/2019 4:28:10 PM 0 0.1 0.20.05 mi 0 0.15 0.30.07 km 1:9,028 Web AppBuilder for ArcGIS Esri, HERE, Garmin, INCREMENT P, NGA, USGS | Minnesota Pollution Control Agency | Esri, HERE | NOAA Atlas 14, Volume 8, Version 2 Location name: Chanhassen, Minnesota, USA* Latitude: 44.8595°, Longitude: -93.596° Elevation: 1007.14 ft** * source: ESRI Maps ** source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Deborah Martin, Sandra Pavlovic, Ishani Roy, Michael St. Laurent, Carl Trypaluk, Dale Unruh, Michael Yekta, Geoffery Bonnin NOAA, National Weather Service, Silver Spring, Maryland PF_tabular | PF_graphical | Maps_&_aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 0.356 (0.275-0.462) 0.423 (0.326-0.549) 0.537 (0.414-0.698) 0.638 (0.488-0.832) 0.784 (0.585-1.06) 0.904 (0.657-1.23) 1.03 (0.724-1.42) 1.16 (0.785-1.63) 1.35 (0.876-1.93) 1.49 (0.945-2.15) 10-min 0.521 (0.403-0.677) 0.619 (0.478-0.803) 0.786 (0.606-1.02) 0.934 (0.715-1.22) 1.15 (0.856-1.55) 1.32 (0.963-1.79) 1.51 (1.06-2.08) 1.70 (1.15-2.39) 1.97 (1.28-2.82) 2.19 (1.38-3.15) 15-min 0.636 (0.492-0.825) 0.754 (0.583-0.980) 0.959 (0.739-1.25) 1.14 (0.872-1.49) 1.40 (1.04-1.89) 1.61 (1.17-2.19) 1.84 (1.29-2.53) 2.07 (1.40-2.91) 2.40 (1.56-3.44) 2.67 (1.69-3.84) 30-min 0.893 (0.690-1.16) 1.06 (0.822-1.38) 1.36 (1.05-1.77) 1.62 (1.24-2.11) 2.00 (1.49-2.69) 2.31 (1.68-3.13) 2.63 (1.85-3.63) 2.98 (2.01-4.18) 3.46 (2.25-4.95) 3.84 (2.43-5.53) 60-min 1.16 (0.898-1.51) 1.38 (1.06-1.79) 1.77 (1.36-2.30) 2.13 (1.63-2.78) 2.68 (2.01-3.65) 3.15 (2.30-4.30) 3.66 (2.58-5.07) 4.21 (2.85-5.94) 4.99 (3.26-7.17) 5.63 (3.56-8.11) 2-hr 1.43 (1.12-1.83) 1.69 (1.32-2.17) 2.18 (1.70-2.80) 2.64 (2.05-3.41) 3.37 (2.57-4.55) 3.99 (2.96-5.41) 4.68 (3.35-6.44) 5.43 (3.73-7.62) 6.52 (4.31-9.31) 7.42 (4.75-10.6) 3-hr 1.60 (1.26-2.03) 1.88 (1.48-2.39) 2.42 (1.90-3.09) 2.96 (2.31-3.78) 3.81 (2.94-5.14) 4.56 (3.41-6.16) 5.39 (3.89-7.40) 6.32 (4.38-8.83) 7.68 (5.11-10.9) 8.80 (5.66-12.5) 6-hr 1.88 (1.50-2.36) 2.20 (1.75-2.76) 2.83 (2.25-3.57) 3.46 (2.74-4.37) 4.48 (3.50-5.99) 5.39 (4.08-7.21) 6.40 (4.68-8.71) 7.54 (5.29-10.4) 9.20 (6.20-13.0) 10.6 (6.89-14.9) 12-hr 2.13 (1.72-2.64) 2.52 (2.03-3.12) 3.25 (2.61-4.04) 3.94 (3.15-4.91) 5.01 (3.94-6.56) 5.94 (4.54-7.82) 6.96 (5.13-9.32) 8.07 (5.71-11.0) 9.69 (6.59-13.5) 11.0 (7.25-15.4) 24-hr 2.49 (2.04-3.05) 2.86 (2.34-3.50) 3.56 (2.90-4.37) 4.24 (3.44-5.22) 5.33 (4.25-6.90) 6.28 (4.86-8.17) 7.32 (5.47-9.71) 8.49 (6.08-11.5) 10.2 (7.01-14.1) 11.6 (7.72-16.0) 2-day 2.90 (2.41-3.50) 3.25 (2.70-3.93) 3.94 (3.25-4.77) 4.61 (3.79-5.60) 5.70 (4.60-7.29) 6.65 (5.22-8.56) 7.72 (5.84-10.1) 8.91 (6.46-11.9) 10.7 (7.42-14.6) 12.1 (8.15-16.6) 3-day 3.15 (2.63-3.77) 3.54 (2.95-4.24) 4.28 (3.56-5.14) 4.99 (4.12-6.01) 6.10 (4.95-7.72) 7.08 (5.58-9.01) 8.15 (6.20-10.6) 9.34 (6.81-12.4) 11.1 (7.75-15.0) 12.5 (8.46-17.0) 4-day 3.34 (2.81-3.98) 3.78 (3.17-4.50) 4.58 (3.83-5.47) 5.33 (4.43-6.39) 6.48 (5.28-8.13) 7.47 (5.91-9.44) 8.55 (6.53-11.0) 9.73 (7.12-12.8) 11.4 (8.03-15.4) 12.8 (8.72-17.4) 7-day 3.87 (3.29-4.56) 4.40 (3.73-5.18) 5.33 (4.51-6.30) 6.17 (5.18-7.31) 7.41 (6.06-9.13) 8.44 (6.72-10.5) 9.53 (7.33-12.1) 10.7 (7.89-13.9) 12.3 (8.75-16.5) 13.7 (9.40-18.4) 10-day 4.39 (3.75-5.13) 4.97 (4.25-5.82) 5.98 (5.09-7.02) 6.87 (5.81-8.09) 8.16 (6.70-9.95) 9.21 (7.38-11.4) 10.3 (7.97-13.0) 11.5 (8.50-14.8) 13.1 (9.32-17.4) 14.4 (9.94-19.3) 20-day 5.99 (5.19-6.91) 6.70 (5.80-7.73) 7.89 (6.80-9.12) 8.88 (7.61-10.3) 10.3 (8.51-12.3) 11.4 (9.20-13.8) 12.5 (9.74-15.5) 13.6 (10.2-17.3) 15.1 (10.9-19.8) 16.3 (11.4-21.6) 30-day 7.39 (6.45-8.44) 8.24 (7.19-9.43) 9.62 (8.36-11.0) 10.7 (9.28-12.4) 12.3 (10.2-14.5) 13.4 (10.9-16.1) 14.6 (11.4-17.9) 15.7 (11.8-19.8) 17.2 (12.4-22.2) 18.3 (12.9-24.1) 45-day 9.18 (8.08-10.4) 10.3 (9.03-11.7) 12.0 (10.5-13.6) 13.3 (11.6-15.2) 15.1 (12.6-17.6) 16.4 (13.4-19.4) 17.6 (13.9-21.4) 18.8 (14.2-23.5) 20.3 (14.7-26.0) 21.3 (15.1-27.9) 60-day 10.7 (9.50-12.1) 12.1 (10.7-13.6) 14.1 (12.4-16.0) 15.7 (13.8-17.9) 17.8 (14.9-20.6) 19.2 (15.8-22.6) 20.5 (16.3-24.8) 21.8 (16.5-27.0) 23.3 (17.0-29.7) 24.2 (17.3-31.7) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top Page 1 of 4Precipitation Frequency Data Server 6/13/2019https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=44.8595&lon=-93.5960&dat... 1Ex Ex Alpha 1Prop Area to System 2Ex Complex 2Prop Complex 1P Underground Routing Diagram for Chanhassen Complex 061319 Prepared by {enter your company name here}, Printed 6/25/2019 HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Subcat Reach Pond Link MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86"Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 2HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1Ex: Ex Alpha Runoff = 3.81 cfs @ 12.44 hrs, Volume= 0.402 af, Depth= 1.54" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86" Area (sf) CN Description 26,259 98 Paved parking, HSG D 90,481 80 >75% Grass cover, Good, HSG D 19,433 98 Paved parking, HSG D 136,173 86 Weighted Average 90,481 66.45% Pervious Area 45,692 33.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 33.2 300 0.0250 0.15 Sheet Flow, Grass: Dense n= 0.240 P2= 2.86" 0.2 40 0.0400 4.06 Shallow Concentrated Flow, Paved Kv= 20.3 fps 33.4 340 Total Subcatchment 1Ex: Ex Alpha Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)4 3 2 1 0 MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86" Runoff Area=136,173 sf Runoff Volume=0.402 af Runoff Depth=1.54" Flow Length=340' Tc=33.4 min CN=86 3.81 cfs MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86"Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 3HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1Prop: Area to System Runoff = 12.28 cfs @ 12.06 hrs, Volume= 0.529 af, Depth= 2.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86" Area (sf) CN Description 71,645 98 Paved parking, HSG D 45,095 80 >75% Grass cover, Good, HSG D 19,433 98 Paved parking, HSG D 136,173 92 Weighted Average 45,095 33.12% Pervious Area 91,078 66.88% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.1 35 0.3300 0.27 Sheet Flow, Grass: Dense n= 0.240 P2= 2.86" 2.0 220 0.0310 1.81 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 4.1 255 Total Subcatchment 1Prop: Area to System Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)13 12 11 10 9 8 7 6 5 4 3 2 1 0 MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86" Runoff Area=136,173 sf Runoff Volume=0.529 af Runoff Depth=2.03" Flow Length=255' Tc=4.1 min CN=92 12.28 cfs MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86"Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 4HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2Ex: Complex Runoff = 77.74 cfs @ 12.10 hrs, Volume= 4.044 af, Depth= 2.12" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86" Area (sf) CN Description 285,472 80 >75% Grass cover, Good, HSG D 711,332 98 Paved parking, HSG D 996,804 93 Weighted Average 285,472 28.64% Pervious Area 711,332 71.36% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.2 80 0.2500 0.42 Sheet Flow, Grass: Short n= 0.150 P2= 2.86" 3.1 300 0.0200 1.62 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 1.4 500 0.0100 5.94 10.50 Pipe Channel, 18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38' n= 0.013 Concrete pipe, bends & connections 7.7 880 Total Subcatchment 2Ex: Complex Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86" Runoff Area=996,804 sf Runoff Volume=4.044 af Runoff Depth=2.12" Flow Length=880' Tc=7.7 min CN=93 77.74 cfs MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86"Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 5HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2Prop: Complex Runoff = 77.74 cfs @ 12.10 hrs, Volume= 4.044 af, Depth= 2.12" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86" Area (sf) CN Description 269,034 80 >75% Grass cover, Good, HSG D 727,770 98 Paved parking, HSG D 996,804 93 Weighted Average 269,034 26.99% Pervious Area 727,770 73.01% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.2 80 0.2500 0.42 Sheet Flow, Grass: Short n= 0.150 P2= 2.86" 3.1 300 0.0200 1.62 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 1.4 500 0.0100 5.94 10.50 Pipe Channel, 18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38' n= 0.013 Concrete pipe, bends & connections 7.7 880 Total Subcatchment 2Prop: Complex Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86" Runoff Area=996,804 sf Runoff Volume=4.044 af Runoff Depth=2.12" Flow Length=880' Tc=7.7 min CN=93 77.74 cfs MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86"Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 6HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Pond 1P: Underground Inflow Area = 3.126 ac, 66.88% Impervious, Inflow Depth = 2.03" for 2y 24hr event Inflow = 12.28 cfs @ 12.06 hrs, Volume= 0.529 af Outflow = 0.91 cfs @ 13.02 hrs, Volume= 0.529 af, Atten= 93%, Lag= 57.3 min Primary = 0.91 cfs @ 13.02 hrs, Volume= 0.529 af Routing by Stor-Ind method, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs Peak Elev= 997.35' @ 13.02 hrs Surf.Area= 28,442 sf Storage= 11,544 cf Plug-Flow detention time= 187.3 min calculated for 0.529 af (100% of inflow) Center-of-Mass det. time= 187.3 min ( 979.1 - 791.8 ) Volume Invert Avail.Storage Storage Description #1 996.60' 9,991 cf 54.35'W x 261.66'L x 3.00'H Prismatoid 42,664 cf Overall - 17,687 cf Embedded = 24,977 cf x 40.0% Voids #2 996.60' 17,687 cf ADS_StormTech SC-740 +Cap x 385 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 385 Chambers in 11 Rows #3 996.10' 2,844 cf 54.35'W x 261.66'L x 0.50'H Prismatoid 7,111 cf Overall x 40.0% Voids 30,522 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 997.05'18.0" Round Culvert L= 22.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 997.05' / 996.90' S= 0.0068 '/' Cc= 0.900 n= 0.010 PVC, smooth interior, Flow Area= 1.77 sf #2 Primary 995.10'4.0" Round Culvert L= 22.0' CPP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 995.10' / 995.00' S= 0.0045 '/' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 0.09 sf Primary OutFlow Max=0.91 cfs @ 13.02 hrs HW=997.35' (Free Discharge) 1=Culvert (Barrel Controls 0.41 cfs @ 2.47 fps) 2=Culvert (Barrel Controls 0.49 cfs @ 5.67 fps) MN-RPBCWD_v1_Atlas14_24-hr2y_S1 2y 24hr Rainfall=2.86"Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 7HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Pond 1P: Underground Inflow Primary Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=3.126 ac Peak Elev=997.35' Storage=11,544 cf 12.28 cfs 0.91 cfs MN-Snowmelt_10d_100yr 10Day Rainfall=7.20", AMC=4Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 8HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1Ex: Ex Alpha Runoff = 0.59 cfs @ 121.54 hrs, Volume= 1.812 af, Depth> 6.95" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-Snowmelt_10d_100yr 10Day Rainfall=7.20", AMC=4 Area (sf) CN Adj Description 26,259 98 Paved parking, HSG D 90,481 80 >75% Grass cover, Good, HSG D 19,433 98 Paved parking, HSG D 136,173 86 98 Weighted Average, AMC Adjusted 90,481 66.45% Pervious Area 45,692 33.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 33.2 300 0.0250 0.15 Sheet Flow, Grass: Dense n= 0.240 P2= 2.86" 0.2 40 0.0400 4.06 Shallow Concentrated Flow, Paved Kv= 20.3 fps 33.4 340 Total Subcatchment 1Ex: Ex Alpha Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (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 MN-Snowmelt_10d_100yr 10Day Rainfall=7.20" AMC=4 Runoff Area=136,173 sf Runoff Volume=1.812 af Runoff Depth>6.95" Flow Length=340' Tc=33.4 min AMC Adjusted CN=98 0.59 cfs MN-Snowmelt_10d_100yr 10Day Rainfall=7.20", AMC=4Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 9HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1Prop: Area to System Runoff = 0.60 cfs @ 121.23 hrs, Volume= 1.813 af, Depth> 6.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-Snowmelt_10d_100yr 10Day Rainfall=7.20", AMC=4 Area (sf) CN Adj Description 71,645 98 Paved parking, HSG D 45,095 80 >75% Grass cover, Good, HSG D 19,433 98 Paved parking, HSG D 136,173 92 98 Weighted Average, AMC Adjusted 45,095 33.12% Pervious Area 91,078 66.88% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.1 35 0.3300 0.27 Sheet Flow, Grass: Dense n= 0.240 P2= 2.86" 2.0 220 0.0310 1.81 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 4.1 255 Total Subcatchment 1Prop: Area to System Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (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 MN-Snowmelt_10d_100yr 10Day Rainfall=7.20" AMC=4 Runoff Area=136,173 sf Runoff Volume=1.813 af Runoff Depth>6.96" Flow Length=255' Tc=4.1 min AMC Adjusted CN=98 0.60 cfs MN-Snowmelt_10d_100yr 10Day Rainfall=7.20", AMC=4Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 10HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2Ex: Complex Runoff = 4.37 cfs @ 121.26 hrs, Volume= 13.271 af, Depth> 6.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-Snowmelt_10d_100yr 10Day Rainfall=7.20", AMC=4 Area (sf) CN Adj Description 285,472 80 >75% Grass cover, Good, HSG D 711,332 98 Paved parking, HSG D 996,804 93 98 Weighted Average, AMC Adjusted 285,472 28.64% Pervious Area 711,332 71.36% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.2 80 0.2500 0.42 Sheet Flow, Grass: Short n= 0.150 P2= 2.86" 3.1 300 0.0200 1.62 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 1.4 500 0.0100 5.94 10.50 Pipe Channel, 18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38' n= 0.013 Concrete pipe, bends & connections 7.7 880 Total Subcatchment 2Ex: Complex Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)4 3 2 1 0 MN-Snowmelt_10d_100yr 10Day Rainfall=7.20" AMC=4 Runoff Area=996,804 sf Runoff Volume=13.271 af Runoff Depth>6.96" Flow Length=880' Tc=7.7 min AMC Adjusted CN=98 4.37 cfs MN-Snowmelt_10d_100yr 10Day Rainfall=7.20", AMC=4Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 11HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2Prop: Complex Runoff = 4.37 cfs @ 121.26 hrs, Volume= 13.271 af, Depth> 6.96" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-Snowmelt_10d_100yr 10Day Rainfall=7.20", AMC=4 Area (sf) CN Adj Description 269,034 80 >75% Grass cover, Good, HSG D 727,770 98 Paved parking, HSG D 996,804 93 98 Weighted Average, AMC Adjusted 269,034 26.99% Pervious Area 727,770 73.01% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.2 80 0.2500 0.42 Sheet Flow, Grass: Short n= 0.150 P2= 2.86" 3.1 300 0.0200 1.62 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 1.4 500 0.0100 5.94 10.50 Pipe Channel, 18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38' n= 0.013 Concrete pipe, bends & connections 7.7 880 Total Subcatchment 2Prop: Complex Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)4 3 2 1 0 MN-Snowmelt_10d_100yr 10Day Rainfall=7.20" AMC=4 Runoff Area=996,804 sf Runoff Volume=13.271 af Runoff Depth>6.96" Flow Length=880' Tc=7.7 min AMC Adjusted CN=98 4.37 cfs MN-Snowmelt_10d_100yr 10Day Rainfall=7.20", AMC=4Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 12HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Pond 1P: Underground Inflow Area = 3.126 ac, 66.88% Impervious, Inflow Depth > 6.96" for 10Day event Inflow = 0.60 cfs @ 121.23 hrs, Volume= 1.813 af Outflow = 0.40 cfs @ 123.39 hrs, Volume= 1.813 af, Atten= 34%, Lag= 129.5 min Primary = 0.40 cfs @ 123.39 hrs, Volume= 1.813 af Routing by Stor-Ind method, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs Peak Elev= 996.64' @ 123.39 hrs Surf.Area= 28,442 sf Storage= 3,279 cf Plug-Flow detention time= 27.5 min calculated for 1.813 af (100% of inflow) Center-of-Mass det. time= 25.3 min ( 7,404.8 - 7,379.4 ) Volume Invert Avail.Storage Storage Description #1 996.60' 9,991 cf 54.35'W x 261.66'L x 3.00'H Prismatoid 42,664 cf Overall - 17,687 cf Embedded = 24,977 cf x 40.0% Voids #2 996.60' 17,687 cf ADS_StormTech SC-740 +Cap x 385 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 385 Chambers in 11 Rows #3 996.10' 2,844 cf 54.35'W x 261.66'L x 0.50'H Prismatoid 7,111 cf Overall x 40.0% Voids 30,522 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 997.05'18.0" Round Culvert L= 22.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 997.05' / 996.90' S= 0.0068 '/' Cc= 0.900 n= 0.010 PVC, smooth interior, Flow Area= 1.77 sf #2 Primary 995.10'4.0" Round Culvert L= 22.0' CPP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 995.10' / 995.00' S= 0.0045 '/' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 0.09 sf Primary OutFlow Max=0.40 cfs @ 123.39 hrs HW=996.64' (Free Discharge) 1=Culvert ( Controls 0.00 cfs) 2=Culvert (Barrel Controls 0.40 cfs @ 4.56 fps) MN-Snowmelt_10d_100yr 10Day Rainfall=7.20", AMC=4Chanhassen Complex 061319 Printed 6/25/2019Prepared by {enter your company name here} Page 13HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Pond 1P: Underground Inflow Primary Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (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=3.126 ac Peak Elev=996.64' Storage=3,279 cf 0.60 cfs 0.40 cfs MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24"Chanhassen Complex 06131 Printed 6/25/2019Prepared by {enter your company name here} Page 14HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1Ex: Ex Alpha Runoff = 7.04 cfs @ 12.44 hrs, Volume= 0.720 af, Depth= 2.76" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24" Area (sf) CN Description 26,259 98 Paved parking, HSG D 90,481 80 >75% Grass cover, Good, HSG D 19,433 98 Paved parking, HSG D 136,173 86 Weighted Average 90,481 66.45% Pervious Area 45,692 33.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 33.2 300 0.0250 0.15 Sheet Flow, Grass: Dense n= 0.240 P2= 2.86" 0.2 40 0.0400 4.06 Shallow Concentrated Flow, Paved Kv= 20.3 fps 33.4 340 Total Subcatchment 1Ex: Ex Alpha Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)7 6 5 4 3 2 1 0 MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24" Runoff Area=136,173 sf Runoff Volume=0.720 af Runoff Depth=2.76" Flow Length=340' Tc=33.4 min CN=86 7.04 cfs MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24"Chanhassen Complex 06131 Printed 6/25/2019Prepared by {enter your company name here} Page 15HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1Prop: Area to System Runoff = 20.20 cfs @ 12.06 hrs, Volume= 0.873 af, Depth= 3.35" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24" Area (sf) CN Description 71,645 98 Paved parking, HSG D 45,095 80 >75% Grass cover, Good, HSG D 19,433 98 Paved parking, HSG D 136,173 92 Weighted Average 45,095 33.12% Pervious Area 91,078 66.88% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.1 35 0.3300 0.27 Sheet Flow, Grass: Dense n= 0.240 P2= 2.86" 2.0 220 0.0310 1.81 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 4.1 255 Total Subcatchment 1Prop: Area to System Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24" Runoff Area=136,173 sf Runoff Volume=0.873 af Runoff Depth=3.35" Flow Length=255' Tc=4.1 min CN=92 20.20 cfs MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24"Chanhassen Complex 06131 Printed 6/25/2019Prepared by {enter your company name here} Page 16HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2Ex: Complex Runoff = 126.35 cfs @ 12.10 hrs, Volume= 6.586 af, Depth= 3.45" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24" Area (sf) CN Description 285,472 80 >75% Grass cover, Good, HSG D 711,332 98 Paved parking, HSG D 996,804 93 Weighted Average 285,472 28.64% Pervious Area 711,332 71.36% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.2 80 0.2500 0.42 Sheet Flow, Grass: Short n= 0.150 P2= 2.86" 3.1 300 0.0200 1.62 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 1.4 500 0.0100 5.94 10.50 Pipe Channel, 18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38' n= 0.013 Concrete pipe, bends & connections 7.7 880 Total Subcatchment 2Ex: Complex Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24" Runoff Area=996,804 sf Runoff Volume=6.586 af Runoff Depth=3.45" Flow Length=880' Tc=7.7 min CN=93 126.35 cfs MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24"Chanhassen Complex 06131 Printed 6/25/2019Prepared by {enter your company name here} Page 17HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2Prop: Complex Runoff = 126.35 cfs @ 12.10 hrs, Volume= 6.586 af, Depth= 3.45" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24" Area (sf) CN Description 269,034 80 >75% Grass cover, Good, HSG D 727,770 98 Paved parking, HSG D 996,804 93 Weighted Average 269,034 26.99% Pervious Area 727,770 73.01% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.2 80 0.2500 0.42 Sheet Flow, Grass: Short n= 0.150 P2= 2.86" 3.1 300 0.0200 1.62 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 1.4 500 0.0100 5.94 10.50 Pipe Channel, 18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38' n= 0.013 Concrete pipe, bends & connections 7.7 880 Total Subcatchment 2Prop: Complex Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24" Runoff Area=996,804 sf Runoff Volume=6.586 af Runoff Depth=3.45" Flow Length=880' Tc=7.7 min CN=93 126.35 cfs MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24"Chanhassen Complex 06131 Printed 6/25/2019Prepared by {enter your company name here} Page 18HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Pond 1P: Underground Inflow Area = 3.126 ac, 66.88% Impervious, Inflow Depth = 3.35" for 10y 24hr event Inflow = 20.20 cfs @ 12.06 hrs, Volume= 0.873 af Outflow = 3.34 cfs @ 12.35 hrs, Volume= 0.873 af, Atten= 83%, Lag= 17.5 min Primary = 3.34 cfs @ 12.35 hrs, Volume= 0.873 af Routing by Stor-Ind method, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs Peak Elev= 997.94' @ 12.35 hrs Surf.Area= 28,442 sf Storage= 17,845 cf Plug-Flow detention time= 153.9 min calculated for 0.873 af (100% of inflow) Center-of-Mass det. time= 153.9 min ( 923.7 - 769.8 ) Volume Invert Avail.Storage Storage Description #1 996.60' 9,991 cf 54.35'W x 261.66'L x 3.00'H Prismatoid 42,664 cf Overall - 17,687 cf Embedded = 24,977 cf x 40.0% Voids #2 996.60' 17,687 cf ADS_StormTech SC-740 +Cap x 385 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 385 Chambers in 11 Rows #3 996.10' 2,844 cf 54.35'W x 261.66'L x 0.50'H Prismatoid 7,111 cf Overall x 40.0% Voids 30,522 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 997.05'18.0" Round Culvert L= 22.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 997.05' / 996.90' S= 0.0068 '/' Cc= 0.900 n= 0.010 PVC, smooth interior, Flow Area= 1.77 sf #2 Primary 995.10'4.0" Round Culvert L= 22.0' CPP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 995.10' / 995.00' S= 0.0045 '/' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 0.09 sf Primary OutFlow Max=3.34 cfs @ 12.35 hrs HW=997.94' (Free Discharge) 1=Culvert (Barrel Controls 2.78 cfs @ 3.68 fps) 2=Culvert (Barrel Controls 0.56 cfs @ 6.44 fps) MN-RPBCWD_v1_Atlas14_24-hr10y_S1 10y 24hr Rainfall=4.24"Chanhassen Complex 06131 Printed 6/25/2019Prepared by {enter your company name here} Page 19HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Pond 1P: Underground Inflow Primary Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Inflow Area=3.126 ac Peak Elev=997.94' Storage=17,845 cf 20.20 cfs 3.34 cfs MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32"Chanhassen Complex 061 Printed 6/25/2019Prepared by {enter your company name here} Page 20HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1Ex: Ex Alpha Runoff = 13.47 cfs @ 12.43 hrs, Volume= 1.478 af, Depth= 5.67" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32" Area (sf) CN Description 26,259 98 Paved parking, HSG D 90,481 80 >75% Grass cover, Good, HSG D 19,433 98 Paved parking, HSG D 136,173 86 Weighted Average 90,481 66.45% Pervious Area 45,692 33.55% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 33.2 300 0.0250 0.15 Sheet Flow, Grass: Dense n= 0.240 P2= 2.86" 0.2 40 0.0400 4.06 Shallow Concentrated Flow, Paved Kv= 20.3 fps 33.4 340 Total Subcatchment 1Ex: Ex Alpha Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32" Runoff Area=136,173 sf Runoff Volume=1.478 af Runoff Depth=5.67" Flow Length=340' Tc=33.4 min CN=86 13.47 cfs MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32"Chanhassen Complex 061 Printed 6/25/2019Prepared by {enter your company name here} Page 21HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 1Prop: Area to System Runoff = 34.34 cfs @ 12.06 hrs, Volume= 1.660 af, Depth= 6.37" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32" Area (sf) CN Description 71,645 98 Paved parking, HSG D 45,095 80 >75% Grass cover, Good, HSG D 19,433 98 Paved parking, HSG D 136,173 92 Weighted Average 45,095 33.12% Pervious Area 91,078 66.88% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 2.1 35 0.3300 0.27 Sheet Flow, Grass: Dense n= 0.240 P2= 2.86" 2.0 220 0.0310 1.81 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 4.1 255 Total Subcatchment 1Prop: Area to System Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32" Runoff Area=136,173 sf Runoff Volume=1.660 af Runoff Depth=6.37" Flow Length=255' Tc=4.1 min CN=92 34.34 cfs MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32"Chanhassen Complex 061 Printed 6/25/2019Prepared by {enter your company name here} Page 22HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2Ex: Complex Runoff = 212.90 cfs @ 12.10 hrs, Volume= 12.373 af, Depth= 6.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32" Area (sf) CN Description 285,472 80 >75% Grass cover, Good, HSG D 711,332 98 Paved parking, HSG D 996,804 93 Weighted Average 285,472 28.64% Pervious Area 711,332 71.36% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.2 80 0.2500 0.42 Sheet Flow, Grass: Short n= 0.150 P2= 2.86" 3.1 300 0.0200 1.62 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 1.4 500 0.0100 5.94 10.50 Pipe Channel, 18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38' n= 0.013 Concrete pipe, bends & connections 7.7 880 Total Subcatchment 2Ex: Complex Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)230 220 210 200 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32" Runoff Area=996,804 sf Runoff Volume=12.373 af Runoff Depth=6.49" Flow Length=880' Tc=7.7 min CN=93 212.90 cfs MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32"Chanhassen Complex 061 Printed 6/25/2019Prepared by {enter your company name here} Page 23HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Subcatchment 2Prop: Complex Runoff = 212.90 cfs @ 12.10 hrs, Volume= 12.373 af, Depth= 6.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32" Area (sf) CN Description 269,034 80 >75% Grass cover, Good, HSG D 727,770 98 Paved parking, HSG D 996,804 93 Weighted Average 269,034 26.99% Pervious Area 727,770 73.01% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.2 80 0.2500 0.42 Sheet Flow, Grass: Short n= 0.150 P2= 2.86" 3.1 300 0.0200 1.62 Sheet Flow, Smooth surfaces n= 0.011 P2= 2.86" 1.4 500 0.0100 5.94 10.50 Pipe Channel, 18.0" Round Area= 1.8 sf Perim= 4.7' r= 0.38' n= 0.013 Concrete pipe, bends & connections 7.7 880 Total Subcatchment 2Prop: Complex Runoff Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)230 220 210 200 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32" Runoff Area=996,804 sf Runoff Volume=12.373 af Runoff Depth=6.49" Flow Length=880' Tc=7.7 min CN=93 212.90 cfs MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32"Chanhassen Complex 061 Printed 6/25/2019Prepared by {enter your company name here} Page 24HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Summary for Pond 1P: Underground Inflow Area = 3.126 ac, 66.88% Impervious, Inflow Depth = 6.37" for 100y 24hr event Inflow = 34.34 cfs @ 12.06 hrs, Volume= 1.660 af Outflow = 11.45 cfs @ 12.19 hrs, Volume= 1.660 af, Atten= 67%, Lag= 7.9 min Primary = 11.45 cfs @ 12.19 hrs, Volume= 1.660 af Routing by Stor-Ind method, Time Span= 0.00-240.00 hrs, dt= 0.01 hrs Peak Elev= 999.40' @ 12.19 hrs Surf.Area= 28,442 sf Storage= 29,392 cf Plug-Flow detention time= 108.5 min calculated for 1.660 af (100% of inflow) Center-of-Mass det. time= 108.5 min ( 862.0 - 753.5 ) Volume Invert Avail.Storage Storage Description #1 996.60' 9,991 cf 54.35'W x 261.66'L x 3.00'H Prismatoid 42,664 cf Overall - 17,687 cf Embedded = 24,977 cf x 40.0% Voids #2 996.60' 17,687 cf ADS_StormTech SC-740 +Cap x 385 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 385 Chambers in 11 Rows #3 996.10' 2,844 cf 54.35'W x 261.66'L x 0.50'H Prismatoid 7,111 cf Overall x 40.0% Voids 30,522 cf Total Available Storage Device Routing Invert Outlet Devices #1 Primary 997.05'18.0" Round Culvert L= 22.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet / Outlet Invert= 997.05' / 996.90' S= 0.0068 '/' Cc= 0.900 n= 0.010 PVC, smooth interior, Flow Area= 1.77 sf #2 Primary 995.10'4.0" Round Culvert L= 22.0' CPP, square edge headwall, Ke= 0.500 Inlet / Outlet Invert= 995.10' / 995.00' S= 0.0045 '/' Cc= 0.900 n= 0.012 Corrugated PP, smooth interior, Flow Area= 0.09 sf Primary OutFlow Max=11.46 cfs @ 12.19 hrs HW=999.40' (Free Discharge) 1=Culvert (Barrel Controls 10.76 cfs @ 6.09 fps) 2=Culvert (Barrel Controls 0.70 cfs @ 8.05 fps) MN-RPBCWD_v1_Atlas14_24-hr100y_S1 100y 24hr Rainfall=7.32"Chanhassen Complex 061 Printed 6/25/2019Prepared by {enter your company name here} Page 25HydroCAD® 10.00-24 s/n 04154 © 2018 HydroCAD Software Solutions LLC Pond 1P: Underground Inflow Primary Hydrograph Time (hours) 2402302202102001901801701601501401301201101009080706050403020100Flow (cfs)38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Inflow Area=3.126 ac Peak Elev=999.40' Storage=29,392 cf 34.34 cfs 11.45 cfs 1 kelfering From:Braun, Loren <lbraun@amengtest.com> Sent:Monday, December 19, 2016 12:19 PM To:kelfering@elferingeng.com Subject:RE: Alpha Addition Kristie, There was a little seepage observed at a depth of 5 feet. The seepage seemed to be a sand seam at about 4 feet down. There was just a trace of water observed at the bottom of the boring at 5 feet while drilling. The MPCA uses 0.06 in/hour, but I believe id more like 0.006 in/hr. Loren B. American Engineering Testing, Inc. Loren W. Braun, PE Principal Engineer, Geotechnical Division 550 Cleveland Avenue North | St. Paul, MN 55114 Direct: 651-789-4689 | Mobile: 612-201-5021 Main: 651-659-9001 | Fax: 651-659-1347 LBraun@amengtest.com | www.amengtest.com From: Kristina Elfering [mailto:kelfering@elferingeng.com] Sent: Monday, December 19, 2016 12:10 PM To: Braun, Loren <lbraun@amengtest.com> Subject: RE: Alpha Addition Loren, One quick clarification question. The boring log for B-1 indicated the ground water level at 19 – 19.5 feet down, however your text says that there was perched ground water at 5.5 feet. Can you confirm that the ground water was encountered at 5.5, because that would also be a reason infiltration would not work given the separation from the pavement. Thanks, Kristie Elfering Elfering & Associates 10062 Flanders Ct NE Blaine, MN 55449 Ph: (763) 780-0450 Ext. 2 2 Fax: (763) 780-0452 kelfering@elferingeng.com From: Braun, Loren [mailto:lbraun@amengtest.com] Sent: Monday, December 19, 2016 11:35 AM To: Justin Schmidt (Jschmidt@lifetimefitness.com) Cc: kelfering@elferingeng.com Subject: Alpha Addition Justin & Kristie, Sorry for the delay, I was out this morning. Loren B. American Engineering Testing, Inc. Loren W. Braun, PE Principal Engineer, Geotechnical Division 550 Cleveland Avenue North | St. Paul, MN 55114 Direct: 651-789-4689 | Mobile: 612-201-5021 Main: 651-659-9001 | Fax: 651-659-1347 LBraun@amengtest.com | www.amengtest.com