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Home My WebLink AboutFORT COLLINS MONTESSORI SCHOOL - FDP200002 - DOCUMENT MARKUPS - ROUND 2 - DRAINAGE REPORTPrepared For: Hauser Architects, P.C. 3780 East 15th Street, Suite 201 Loveland, CO 80538 970-669-8220 Prepared By: Coffey Engineering & Surveying, LLC 4045 St. Cloud Drive, Suite 180 Loveland, CO 80538 970-622-2095 Project No. 2259.03 December 17, 2019 FINAL DRAINAGE REPORT FORT COLLINS MONTESSORI SCHOOL LOT 1, MONTESSORI SUBDIVISION FORT COLLINS, CO 80526 PAGE | 1 Fort Collins Montessori School FINAL DRAINAGE REPORT ENGINEER’S CERTIFICATION I hereby certify that this Final Drainage Report for the design of stormwater management facilities for the Fort Collins Montessori School site was prepared by me, or under my direct supervision, in accordance with the provisions of the City of Fort Collins Stormwater Criteria Manual for the owners thereof. Troy W. Campbell, P.E. Registered Professional Engineer State of Colorado No. 41159 PAGE | 9 H. Modifications of Criteria There are no modifications or variances requested in connection with the design of the stormwater management for the Fort Collins Montessori School development. IV. DRAINAGE FACILITY DESIGN I. General Concept The storm drainage system is designed to safely convey developed storm flows by sheet flow, pipe flow, concentrated swale and gutter flow to the rain gardens and detention pond. The design worksheets included in the Appendices to this Final Drainage Report present details of the hydrologic and hydraulic calculations pertinent to the design of the on-site storm drainage system. A drainage plan, showing the proposed development of the site and developed drainage patterns is included in the map pocket following the Appendices. J. Specific Details The site will utilize on-site detention ponds and rain gardens. Runoff will enter the detention system through proposed rain gardens and PVC pipes. Three rain gardens are provided on-site. The rain gardens were sized based on full build out of Phase II of development. Phase II was split into four drainage basins. Three of these basins are treated with water quality, totaling 80% of the new impervious area. The proposed detention ponds have a capacity of approximately 28,872 cubic feet. The required detention for the site is 27,626 cubic feet. The detention pond will drain through an outlet structure with a release rate of 1.36 cfs. The 100-year release rate was based off the 2-year historic flow rate. The proposed detention pond will have three controlled release rates. The detention pond has a water quality volume of 3,135 cubic feet and a release rate of 0.07 cfs through two 1” orifices at 1’ intervals. Runoff exceeding the water quality elevation of 5086.0 will flow through a grated lid into the 18” outlet pipe. This pipe will be covered by a restrictor plate to control the release rate to 1.36 cfs. Runoff greater than a 100-year event will exit the detention pond through an emergency spillway at a rate no greater than the 100-year developed flow. The 100-year WSEL is 5088.60’ with 1’ of freeboard provided. V. CONCLUSIONS K. Compliance with Standards The drainage design for the Fort Collins Montessori School Site follows the requirements of the Fort Collins Stormwater Criteria Manual as well as the City’s floodplain regulations. Imperviousness Fort Collins Montessori School LID Asphalt Area (acres) Concrete Area (acres) Gravel (acres) Roofs (acres) Lawns (acres) Total Area Percent (I = 100) (I = 100) (I = 40) (I = 90) (I = 2) (acres) Imperviousness - LID1 0.32 0.08 0.00 0.14 0.18 0.72 74% - LID2 0.27 0.13 0.07 0.38 1.10 1.95 41% - LID4 0.20 0.06 0.00 0.15 0.23 0.64 62% 0.25 0.10 0.00 0.07 0.17 0.59 71% Notes: Values from Fort Collins Stormwater Criteria Manual Table 4.1-3 WQCV1 0.235447872 WQCV1 0.2354479 WQCV2 2.994849 WQCV2 0.1459833 WQCV4 0.200261632 WQCV4 0.194434 V1 0.0169522 738.4398699 V2 0.0284667 1240.011245 V4 0.0124438 542.050838 Design Point Basin (s) LID RJP Rational Method Flow LID Calculations.xlsx 12/12/2019 Project: Basin ID: Design Information (Input): Width of Basin Bottom, W = ft Right Triangle OR… Length of Basin Bottom, L = ft Isosceles Triangle OR… Dam Side-slope (H:V), Zd = ft/ft Rectangle OR… Circle / Ellipse OR… Irregular (Use Overide values in cells G32:G52) MINOR MAJOR Storage Requirement from Sheet 'Modified FAA': 0.10 0.54 acre-ft. Stage-Storage Relationship: Storage Requirement from Sheet 'Hydrograph': acre-ft. Storage Requirement from Sheet 'Full-Spectrum': acre-ft. Labels Water Side Basin Basin Surface Surface Volume Surface Volume Target Volumes for WQCV, Minor, Surface Slope Width at Length at Area at Area at Below Area at Below for WQCV, Minor, & Major Storage Elevation (H:V) Stage Stage Stage Stage Stage Stage Stage & Major Storage Stages ft ft/ft ft ft ft2 ft2 User ft3 acres acre-ft Volumes (input) (input) Below El. (output) (output) (output) Overide (output) (output) (output) (for goal seek) 0.00 5083.60 (input) 0 0.000 0.000 0.40 5084.00 0.00 0.00 263 53 0.006 0.001 0.90 5084.50 0.00 0.00 856 332 0.020 0.008 1.40 5085.00 0.00 0.00 1,384 892 0.032 0.020 1.90 5085.50 0.00 0.00 2,211 1,791 0.051 0.041 2.40 5086.00 0.00 0.00 3,163 3,135 0.073 0.072 2.90 5086.50 0.00 0.00 4,227 4,982 0.097 0.114 3.40 5087.00 0.00 0.00 6,749 7,726 0.155 0.177 3.90 5087.50 0.00 0.00 10,528 12,045 0.242 0.277 4.40 5088.00 0.00 0.00 15,591 18,575 0.358 0.426 5.00 5088.60 0.00 0.00 18,733 28,872 0.430 0.663 100-YR 5.50 5089.10 0.00 0.00 21,373 38,899 0.491 0.893 6.00 5089.60 0.00 0.00 30,400 51,842 0.698 1.190 STAGE-STORAGE SIZING FOR DETENTION BASINS Fort Collins Montessori School Check Basin Shape Detention Pond System Detention Pond Outlet Design File_v2.35.xls, Basin 12/12/2019, 3:13 PM Project: Basin ID: WQCV Design Volume (Input): Catchment Imperviousness, Ia = 50.0 percent Catchment Area, A = 4.29 acres Diameter of holes, D = 1.000 inches Depth at WQCV outlet above lowest perforation, H = 2 feet Number of holes per row, N = 1 Vertical distance between rows, h = 12.00 inches OR Number of rows, NL = 2.00 Orifice discharge coefficient, Co = 0.60 Height of slot, H = inches Slope of Basin Trickle Channel, S = 0.010 ft / ft Width of slot, W = inches Time to Drain the Pond = 40 hours Watershed Design Information (Input): 2.4 Percent Soil Type A = 0 % Percent Soil Type B = 100 % Percent Soil Type C/D = 0 % Outlet Design Information (Output): Water Quality Capture Volume, WQCV = 0.229 watershed inches Water Quality Capture Volume (WQCV) = 0.082 acre-feet 0.00 Design Volume (WQCV / 12 * Area * 1.2) Vol = 0.098 acre-feet Outlet area per row, Ao = 0.62 square inches Total opening area at each row based on user-input above, Ao = 0.79 square inches Total opening area at each row based on user-input above, Ao = 0.005 square feet 3 Row 1 Row 2 Row 3 Row 4 Row 5 Row 6 Row 7 Row 8 Row 9 Row 10 Row 11 Row 12 Row 13 Row 14 Row 15 Row 16 Row 17 Row 18 Row 19 Row 20 Row 21 Row 22 Row 23 Row 23 ΣΣΣΣ 5083.60 5084.60 Flow 5083.60 0.0000 0.0000 0.00 5084.00 0.0166 0.0000 0.02 5084.50 0.0249 0.0000 0.02 5085.00 0.0362 0.0249 0.06 5085.50 0.0407 0.0311 0.07 5086.00 0.0407 0.0311 0.07 5086.50 0.0447 0.0362 0.08 5087.00 0.0484 0.0407 0.09 5087.50 0.0519 0.0447 0.10 5088.00 0.0551 0.0484 0.10 5088.60 0.0587 0.0525 0.11 5089.60 0.0643 0.0587 0.12 Central Elevations of Rows of Holes in feet Collection Capacity for Each Row of Holes in cfs STAGE-DISCHARGE SIZING OF THE WATER QUALITY CAPTURE VOLUME (WQCV) OUTLET Fort Collins Montessori School Detention Pond System Detention Pond Outlet Design File_v2.35.xls, WQCV 12/12/2019, 3:14 PM Project: Basin ID: Design Information (input): Bottom Length of Weir L = 18.00 feet Angle of Side Slope Weir Angle = 45.00 degrees Elev. for Weir Crest EL. Crest = 5,088.60 feet Coef. for Rectangular Weir Cw = 2.50 Coef. for Trapezoidal Weir Ct = 2.20 Calculation of Spillway Capacity (output): Water Rect. Triangle Total Total Surface Weir Weir Spillway Pond Elevation Flowrate Flowrate Release Release ft. cfs cfs cfs cfs (linked) (output) (output) (output) (output) 5083.60 0.00 0.00 0.00 0.00 5084.00 0.00 0.00 0.00 0.00 5084.50 0.00 0.00 0.00 0.00 5085.00 0.00 0.00 0.00 0.00 5085.50 0.00 0.00 0.00 0.00 5086.00 0.00 0.00 0.00 0.00 5086.50 0.00 0.00 0.00 0.00 5087.00 0.00 0.00 0.00 0.00 5087.50 0.00 0.00 0.00 0.00 5088.00 0.00 0.00 0.00 0.00 5088.60 0.00 0.00 0.00 0.00 5089.10 15.91 0.39 16.30 16.30 5089.60 45.00 2.20 47.20 47.20 STAGE-DISCHARGE SIZING OF THE SPILLWAY Fort Collins Montessori School Detention Pond System Detention Pond Outlet Design File_v2.35.xls, Spillway 12/12/2019, 3:15 PM LID REQUIREMENTS TOTAL IMPERVIOUS AREA ON SITE 93,654 SQ FT REQUIRED TREATMENT AREA (75%) 70,240 SQ FT TOTAL IMPERVIOUS AREA TREATED BY LID 75,358 SQ FT (80%) BASIN 1 BASIN 2 BASIN 3 BASIN 4 AREA (ACRES) 0.72 1.95 0.59 0.64 IMPERVIOUS AREA (ACRES) 0.54 0.78 0.42 0.41 PERCENT IMPERVIOUS (%) 74 41 71 62 PERCENT OF IMPERVIOUS AREA (%) 25.1 36.3 19.5 19.1 REQUIRED WQCV (INCHES) 0.235 0.146 - 0.194 LID VOLUME REQUIRED (CU. FT.) 738 1240 - 542 LID VOLUME PROVIDED (CU. FT.) 774 1332 - 576 REQUIRED FLAT AREA (SQ. FT) 464 697 - 346 PROVIDED FLAT AREA (SQ. FT) 508 1190 - 378 BASIN SUMMARY Culvert Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Wednesday, Dec 11 2019 Equalizer Pipe-Dentention Pond 2 to Detention Pond 1 Invert Elev Dn (ft) = 5086.20 Pipe Length (ft) = 55.00 Slope (%) = 0.00 Invert Elev Up (ft) = 5086.20 Rise (in) = 18.0 Shape = Circular Span (in) = 18.0 No. Barrels = 1 n-Value = 0.013 Culvert Type = Circular Culvert Culvert Entrance = Smooth tapered inlet throat Coeff. K,M,c,Y,k = 0.534, 0.555, 0.0196, 0.9, 0.2 Embankment Top Elevation (ft) = 5089.60 Top Width (ft) = 24.00 Crest Width (ft) = 20.00 Calculations Qmin (cfs) = 6.60 Qmax (cfs) = 6.60 Tailwater Elev (ft) = (dc+D)/2 Highlighted Qtotal (cfs) = 6.60 Qpipe (cfs) = 6.60 Qovertop (cfs) = 0.00 Veloc Dn (ft/s) = 4.20 Veloc Up (ft/s) = 3.73 HGL Dn (ft) = 5087.45 HGL Up (ft) = 5087.72 Hw Elev (ft) = 5087.82 Hw/D (ft) = 1.08 Flow Regime = Inlet Control Culvert Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Wednesday, Dec 11 2019 Equalizer Pipe-Detention Pond 3 to Detnetion Pond 1 Invert Elev Dn (ft) = 5084.60 Pipe Length (ft) = 83.00 Slope (%) = 0.23 Invert Elev Up (ft) = 5084.79 Rise (in) = 18.0 Shape = Circular Span (in) = 18.0 No. Barrels = 1 n-Value = 0.013 Culvert Type = Circular Culvert Culvert Entrance = Smooth tapered inlet throat Coeff. K,M,c,Y,k = 0.534, 0.555, 0.0196, 0.9, 0.2 Embankment Top Elevation (ft) = 5089.60 Top Width (ft) = 25.00 Crest Width (ft) = 20.00 Calculations Qmin (cfs) = 5.13 Qmax (cfs) = 5.13 Tailwater Elev (ft) = (dc+D)/2 Highlighted Qtotal (cfs) = 5.13 Qpipe (cfs) = 5.13 Qovertop (cfs) = 0.00 Veloc Dn (ft/s) = 3.42 Veloc Up (ft/s) = 4.82 HGL Dn (ft) = 5085.79 HGL Up (ft) = 5085.66 Hw Elev (ft) = 5086.08 Hw/D (ft) = 0.86 Flow Regime = Inlet Control Culvert Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Wednesday, Dec 11 2019 Equalizer Pipe-Detention Pond 4 to Detention Pond 1 Invert Elev Dn (ft) = 5084.61 Pipe Length (ft) = 440.00 Slope (%) = 0.40 Invert Elev Up (ft) = 5086.36 Rise (in) = 18.0 Shape = Circular Span (in) = 18.0 No. Barrels = 1 n-Value = 0.013 Culvert Type = Circular Culvert Culvert Entrance = Smooth tapered inlet throat Coeff. K,M,c,Y,k = 0.534, 0.555, 0.0196, 0.9, 0.2 Embankment Top Elevation (ft) = 5089.60 Top Width (ft) = 100.00 Crest Width (ft) = 20.00 Calculations Qmin (cfs) = 6.92 Qmax (cfs) = 6.92 Tailwater Elev (ft) = (dc+D)/2 Highlighted Qtotal (cfs) = 6.92 Qpipe (cfs) = 6.92 Qovertop (cfs) = 0.00 Veloc Dn (ft/s) = 4.37 Veloc Up (ft/s) = 5.42 HGL Dn (ft) = 5085.87 HGL Up (ft) = 5087.38 Hw Elev (ft) = 5087.89 Hw/D (ft) = 1.02 Flow Regime = Inlet Control Culvert Report Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Friday, Dec 13 2019 Equalizer Pipe-Dentention Pond 1 to Spillway Invert Elev Dn (ft) = 5086.20 Pipe Length (ft) = 55.00 Slope (%) = 0.00 Invert Elev Up (ft) = 5086.20 Rise (in) = 18.0 Shape = Circular Span (in) = 18.0 No. Barrels = 1 n-Value = 0.013 Culvert Type = Circular Culvert Culvert Entrance = Smooth tapered inlet throat Coeff. K,M,c,Y,k = 0.534, 0.555, 0.0196, 0.9, 0.2 Embankment Top Elevation (ft) = 5089.60 Top Width (ft) = 24.00 Crest Width (ft) = 20.00 Calculations Qmin (cfs) = 16.62 Qmax (cfs) = 16.62 Tailwater Elev (ft) = (dc+D)/2 Highlighted Qtotal (cfs) = 16.62 Qpipe (cfs) = 16.62 Qovertop (cfs) = 0.00 Veloc Dn (ft/s) = 9.46 Veloc Up (ft/s) = 9.40 HGL Dn (ft) = 5087.67 HGL Up (ft) = 5088.99 Hw Elev (ft) = 5089.28 Hw/D (ft) = 2.06 Flow Regime = Inlet Control