Loading...
HomeMy WebLinkAbout18 - Design Report - N 25th & Breeze - Stormwater INTRODUCTION The proposed infrastructure improvements will include the construction of N. 25th Avenue from Oak Street to Tschache Lane and the construction Breeze Lane from N. 27th Avenue to N. 25th Avenue. Stormwater runoff from these improvements will be conveyed via curb and gutter channel flow to storm sewer inlets. It will then be routed through storm drainage pipes to a retention pond located in Rose Park and two Stormtech underground retention systems located on east and west boulevards along N. 25th. A Drainage Area Map is included in Appendix A, and calculations for each individual drainage area (total area, weighted C factor, and time of concentration) are included in Appendix B. In addition to the right of way drainage, there will be portions of Lot 5C and Lot 5B included in the stormwater capacity calculations. The remaining portions of the Lot 5B and 5C will retain stormwater runoff on site (see the Palisades Apartments Stormwater Design Report for details). Lot 5A will handle all of the runoff generated from the proposed development on site (see Silver Creek Apartments Stormwater Design Report for details). STORM SEWER FACILITIES DESIGN Storm sewer facilities were sized for the 25-yr storm using Manning’s Equation. For each inlet, the contributing area, weighted C factor, and time of concentration were calculated. These values were input into Manning’s Equation to check capacity and flow characteristics for inlets, storm drain pipes, and curb gutters. All curbs are designed to maintain 0.15’ freeboard per C.O.B. Design Manual Section IV.C.5. For the purposes of this report, each pipe section was named to match the associated upstream structure. Pipe sizing calculations are included in Appendix C. RETENTION POND DESIGN The proposed retention pond has been sized according to City of Bozeman Design Standards. The proposed Retention Pond is sized to retain runoff from the 10-year storm event. Calculations used for sizing each pond can be found in Appendix D. Design pond capacities were calculated using volume surfaces in AutoCAD Civil 3D. Proposed Retention Pond #1 Retention Pond #1 is the Southern retention pond located in Rose Park. Retention Pond 1 will receive runoff from the southern 78 percent (approx.) of N. 25th Avenue, Breeze Lane, and portions of Lot 5C and Lot 5B. Runoff from the lots and boulevard will drain to the curb and gutter system and discharge to the storm inlets on the East and West side of N. 25th. From there, a 12” PVC storm main will transport the storm water to Retention Pond 1. The required pond volume was calculated to be 4,518 cubic feet. The provided pond volume is 4,727 cubic feet at a water depth of 1.5’. Supporting calculations for the pond sizing can be found in Appendix C. UNDERGROUND RETENTION CHAMBER DESIGN The remaining runoff will be conveyed to two curb inlets on the East and West side of the designed low point in N. 25th. These catch basins will convey runoff to the two Stormtech Retention Chambers Located beneath the boulevards. West Side (Drainage Area 2) Chamber Design The west side will receive runoff from N. 25th and a small portion of Lot 5C. The required storage volume for Drainage Area 2 is 981 cubic feet. The Stormtech system will be a single row consisting of 5 chambers and 2 end caps. Each chamber has a storage volume of 179 cubic feet and each end cap has a storage volume of 47 cubic feet, yielding a bare storage volume of 988 cubic feet. There is an additional 195 cubic feet of storage in the perimeter gravel in the system. This yields a total system storage volume of 1,184 cubic feet. Stormtech details and system information can be found in Appendix D and on sheet C5.2. East Side (Drainage Area 3) Chamber Design The East side will receive the remaining runoff from N. 25th. The required storage volume for Drainage Area 3 is 406 cubic feet, supporting calculations can be found in Appendix B. The Stormtech system will be a single row consisting of 2 chambers and 2 end caps. Each chamber has a storage volume of 179 cubic feet and each end cap has a storage volume of 47 cubic feet, yielding a bare storage volume of 452 cubic feet. There is an additional 136 cubic feet of storage in the perimeter gravel in the system. This yields a total system storage volume of 588 cubic feet. Stormtech details and system information can be found in Appendix D and on sheet C5.2. APPENDIX A DRAINAGE AREA MAP APPENDIX B DRAINAGE AREA CALULATIONS DRAINAGE AREA 2B (LOT 5C) RUNOFF VOLUME 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2 )C * Area Hardscape 0.95 7289 6925 Landscape 0.2 7856 1571 Total 15145 8496 C=Weighted C Factor 0.56 2. Calculate Runoff Volume Q = CIA V=7200Q C = Weighted C Factor 0.56 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.35 Q = runoff (cfs) 0.08 V = RUNOFF VOL (ft3) 576 2. Calculate Tc (Time to Concentration) Tc Overland Flow Tc = 1.87 (1.1-CCf)D1/2/S1/3 Storm S = Slope of Basin (%) 2.00 Return (yrs)Cf C = Rational Method Runoff Coefficient 0.20 2 to 10 1 Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft) 12.5 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)4.62 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R2/3 S1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (ft/ft) 0.0078 L = length of gutter (ft) 200 V = mean velocity (ft/s) 2.65 Tc Gutter Flow (minutes) =1.26 Tc Total =5.88 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.70 (calculated above) I = 0.78 Tc-0.64 (in/hr)3.45 (25-yr storm) A = area (acres) 0.20 (calculated above) Q = REQUIRED GUTTER CAPACITY (cfs)0.47 (assuming no carry flow) PROVIDED GUTTER CAPACITY 1. Calculate Gutter Capacity @ 0.15' Below Top of Curb Q = (1.486/n)AR2/3 S1/2 n = Mannings Coefficient 0.013 A = Area (ft2)1.24 (0.15' below top of curb) P = Wetted perimeter (ft) 9.23 (0.15' below top of curb) R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (ft/ft) 0.0078 Q = PROVIDED GUTTER CAPACITY (cfs)3.28 DRAINAGE AREA 3 RUNOFF VOLUME 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2 )C * Area ROW 25th 0.70 8556 5989 Total 8556 5989 C=Weighted C Factor 0.70 2. Calculate Runoff Volume Q = CIA V=7200Q C = Weighted C Factor 0.70 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.20 Q = runoff (cfs) 0.06 V = RUNOFF VOL (ft3) 406 2. Calculate Tc (Time to Concentration) Tc Overland Flow Tc = 1.87 (1.1-CCf)D1/2/S1/3 Storm S = Slope of Basin (%) 2.00 Return (yrs)Cf C = Rational Method Runoff Coefficient 0.20 2 to 10 1 Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft) 12.5 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)4.62 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R2/3 S1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (ft/ft) 0.0093 L = length of gutter (ft) 993 V = mean velocity (ft/s) 2.89 Tc Gutter Flow (minutes) =5.73 Tc Total =10.35 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.70 (calculated above) I = 0.78 Tc-0.64 (in/hr)2.40 (25-yr storm) A = area (acres) 1.74 (calculated above) Q = REQUIRED GUTTER CAPACITY (cfs)2.93 (assuming no carry flow) PROVIDED GUTTER CAPACITY 1. Calculate Gutter Capacity @ 0.15' Below Top of Curb Q = (1.486/n)AR2/3 S1/2 n = Mannings Coefficient 0.013 A = Area (ft2)1.24 (0.15' below top of curb) P = Wetted perimeter (ft) 9.23 (0.15' below top of curb) R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (ft/ft) 0.0093 Q = PROVIDED GUTTER CAPACITY (cfs)3.58 DRAINAGE AREA 1A RUNOFF VOLUME 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2 )C * Area ROW Breeze Lane 0.71 14849 10580 ROW 25th 0.70 60843 42590 Total 75692 53170 C=Weighted C Factor 0.70 2. Calculate Runoff Volume Q = CIA V=7200Q C = Weighted C Factor 0.70 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 1.74 Q = runoff (cfs) 0.50 V = RUNOFF VOL (ft3) 3603 DRAINAGE AREA 1B (LOT 5B) RUNOFF VOLUME 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2 )C * Area Hardscape 0.95 2860 2717 Landscape 0.2 6127 1225 Total 8987 3942 C=Weighted C Factor 0.44 2. Calculate Runoff Volume Q = CIA V=7200Q C = Weighted C Factor 0.44 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.21 Q = runoff (cfs) 0.04 V = RUNOFF VOL (ft3) 267 DRAINAGE AREA 1C (LOT 5C) RUNOFF VOLUME 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft 2 )C * Area Hardscape 0.95 8975 8526 Landscape 0.2 5152 1030 Total 14127 9557 C=Weighted C Factor 0.68 2. Calculate Runoff Volume Q = CIA V=7200Q C = Weighted C Factor 0.68 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.32 Q = runoff (cfs) 0.09 V = RUNOFF VOL (ft3) 648 2. Calculate Tc (Time to Concentration) Tc Overland Flow Tc = 1.87 (1.1-CCf)D1/2/S1/3 Storm S = Slope of Basin (%) 2.00 Return (yrs)Cf C = Rational Method Runoff Coefficient 0.20 2 to 10 1 Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1 D = Length of Basin (ft) 12.5 26 to 50 1.2 51 to 100 1.25 Tc Overland Flow (minutes)4.62 Tc Gutter Flow Tc = L/V/60 V = (1.486/n)R2/3 S1/2 n = Mannings Coefficient 0.013 R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (ft/ft) 0.0078 L = length of gutter (ft) 200 V = mean velocity (ft/s) 2.65 Tc Gutter Flow (minutes) =1.26 Tc Total =5.88 3. Calculate Flow (Rational Formula) Q = CIA C = Weighted C Factor 0.70 (calculated above) I = 0.78 Tc-0.64 (in/hr)3.45 (25-yr storm) A = area (acres) 0.20 (calculated above) Q = REQUIRED GUTTER CAPACITY (cfs)0.47 (assuming no carry flow) PROVIDED GUTTER CAPACITY 1. Calculate Gutter Capacity @ 0.15' Below Top of Curb Q = (1.486/n)AR2/3 S1/2 n = Mannings Coefficient 0.013 A = Area (ft2)1.24 (0.15' below top of curb) P = Wetted perimeter (ft) 9.23 (0.15' below top of curb) R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb) S = slope (ft/ft) 0.0078 Q = PROVIDED GUTTER CAPACITY (cfs)3.28 DRAINAGE AREA 2A RUNOFF VOLUME 1. Calculate Area and Weighted C Factor Contributing Area C Area (ft2 )C * Area ROW 25th 0.70 8535 5975 Total 8535 5975 C=Weighted C Factor 0.70 2. Calculate Runoff Volume Q = CIA V=7200Q C = Weighted C Factor 0.70 I = intensity (in/hr) 0.41 (10 yr, 2hr storm) A = Area (acres) 0.20 Q = runoff (cfs) 0.06 V = RUNOFF VOL (ft3) 405 APPENDIX C STORM SEWER FACILITIES CALCULATIONS TOTAL POND VOLUMES TOTAL RUNOFF VOL (ft3) Drainage Area 1 4518 Drainage Area 2 981 Drainage Area 3 406 PROVIDED VOL (ft3) Retention Pond 1 4727 Drainage Area 2 Chambers 1184 Drainage Area 3 Chambers 588 MANNING'S EQUATION FOR PIPE FLOW (PROVIDED CAPACITY) Pipe: N/A Location: N. 25th Storm Inlets INPUT D= 12 inches d= 11.26 inches Mannings Formula n= 0.013 mannings q=57.7 degrees Q=(1.486/n)ARh2/3S1/2 S= 0.005 slope in/in R=A/P A=cross sectional area P=wetted perimeter V=(1.49/n)Rh2/3S1/2 S=slope of channel Q=V x A n=Manning's roughness coefficient Solution to Mannings Equation Area,ft2 Wetted Perimeter, ft Hydraulic Radius, ft velocity ft/s flow, cfs PVC 0.013 0.77 2.64 0.29 3.54 2.71 PE (<9"dia) 0.015 PE (>12"dia) 0.02 PE(9-12"dia) 0.017 CMP 0.025 ADS N12 0.012 HCMP 0.023 Conc 0.013 Manning's n-values d q D APPENDIX D STORMTECH RETENTION CHAMBER INFORMATION 45"(1140 mm) 24"(600 mm) MIN* 8'(2.4 m)MAX 12" (300 mm) TYP77" (1950 mm) 12" (300 mm) MIN 9"(230 mm) MIN DEPTH OF STONE TO BE DETERMINEDBY SITE DESIGN ENGINEER 9" (230 mm) MIN6" (150 mm) MIN MC-3500END CAP PERIMETER STONE EXCAVATION WALL(CAN BE SLOPEDOR VERTICAL) PAVEMENT LAYER (DESIGNEDBY SITE DESIGN ENGINEER) CHAMBERS SHALL BE BE DESIGNED IN ACCORDANCE WITH ASTM F2787"STANDARD PRACTICE FOR STRUCTURAL DESIGN OF THERMOPLASTICCORRUGATED WALL STORMWATER COLLECTION CHAMBERS". GRANULAR WELL-GRADED SOIL/AGGREGATE MIXTURES, <35%FINES, COMPACT IN 12" (300 mm) MAX LIFTS TO 95% PROCTORDENSITY. SEE THE TABLE OF ACCEPTABLE FILL MATERIALS. ADS GEOSYTHETICS 601T NON-WOVENGEOTEXTILE ALL AROUND CLEAN, CRUSHED,ANGULAR EMBEDMENT STONE CHAMBERS SHALL MEET ASTM F2418 "STANDARDSPECIFICATION FOR POLYPROPLENE (PP) CORRUGATEDWALL STORMWATER COLLECTION CHAMBERS". EMBEDMENT STONE SHALL BE A CLEAN, CRUSHED AND ANGULARSTONE WITH AN AASHTO M43 DESIGNATION BETWEEN #3 AND #4 SITE DESIGN ENGINEER IS RESPONSIBLE FOR ENSURINGTHE REQUIRED BEARING CAPACITY OF SOILS *MINIMUM COVER TO BOTTOM OF FLEXIBLE PAVEMENT. FOR UNPAVED INSTALLATIONS WHERE RUTTING FROM VEHICLES MAY OCCUR, INCREASE COVER TO 30" (750 mm). STORMTECH MC-3500 CHAMBER Designed to meet the most stringent industry performance standards for superior structural integrity while providing designers with a cost-effective method to save valuable land and protect water resources. The StormTech system is designed primarily to be used under parking lots, thus maximizing land usage for private (commercial) and public applications. StormTech chambers can also be used in conjunction with Green Infrastructure, thus enhancing the performance and extending the service life of these practices. STORMTECH MC-3500 CHAMBER (not to scale) Nominal Chamber Specifications Size (L x W x H) 90” x 77” x 45” 2,286 mm x 1,956 mm x 1,143 mm Chamber Storage 109.9 ft3 (3.11 m3) Min. Installed Storage* 178.9 ft3 (5.06 m3) Weight 134 lbs (60.8 kg) Shipping 15 chambers/pallet 7 end caps/pallet 7 pallets/truck *Assumes a minimum of 12” (300 mm) of stone above, 9” (230 mm) of stone below chambers, 9” (230 mm) of stone between chambers/end caps and 40% stone porosity. STORMTECH MC-3500 END CAP (not to scale) Nominal End Cap Specifications Size (L x W x H) 26.5” x 71” x 45.1” 673 mm x 1,803 mm x 1,145 mm End Cap Storage 14.9 ft3 (1.30 m3) Min. Installed Storage* 46.0 ft3 (1.30 m3) Weight 49 lbs (22.2 kg) *Assumes a minimum of 12” (300 mm) of stone above, 9” (230 mm) of stone below, 6” (150 mm) of stone perimeter, 9” (230 mm) of stone between chambers/end caps and 40% stone porosity. THE MOST ADVANCED NAME IN WATER MANAGEMENT SOLUTIONS TM Advanced Drainage Systems, Inc. 4640 Trueman Blvd., Hilliard, OH 43026 1-800-821-6710 www.ads-pipe.com For more information on the StormTech MC-3500 Chamber and other ADS products, please contact our Customer Service Representatives at 1-800-821-6710 ADS “Terms and Conditions of Sale” are available on the ADS website, www.ads-pipe.com The ADS logo and the Green Stripe are registered trademarks of Advanced Drainage Systems, Inc. StormTech® is a registered trademark of StormTech, Inc. © 2017 Advanced Drainage Systems, Inc. #S150909 09/17 CS TOOLDESIGN Working on a project? Visit us at www.stormtech.com and utilize the StormTech Design Tool MC-3500 CHAMBER SPECIFICATION Bare Chamber Storage ft3 (m3) Chamber and Stone Foundation Depth in. (mm) 9” (230 mm)12” (300 mm)15” (375 mm)18” (450 mm) MC-3500 Chamber 109.9 (3.11)178.9 (5.06)184.0 (5.21)189.2 (5.36)194.3 (5.5) MC-3500 End Cap 14.9 (.42)46.0 (1.33)47.7 (1.35)49.4 (1.40)51.1 (1.45) ENGLISH TONS (yds3)Stone Foundation Depth 9”12”15”18” MC-3500 Chamber 9.1 (6.4)9.7 (6.9)10.4 (7.3)11.1 (7.8) MC-3500 End Cap 4.1 (2.9)4.3 (3.0)4.5 (3.2)4.5 (3.2) METRIC KILOGRAMS (m3)230 mm 300 mm 375 mm 450 mm MC-3500 Chamber 8,220 (4.9)8,831 (5.3)9,443 (5.6)10,054 (6.0) MC-3500 End Cap 3,699 (2.2)3,900 (2.3)4,100 (2.5)4,301 (2.6) Note: Assumes 12” (300 mm) of stone above and 9” (230 mm) row spacing and 6” (150 mm) of perimeter stone in front of end caps. STORAGE VOLUME PER CHAMBER FT3 (M3) AMOUNT OF STONE PER CHAMBER Stone Foundation Depth 9” (230 mm)12” (300 mm)15” (375mm)18” (450 mm) MC-3500 Chamber 12.4 (9.5)12.8 (9.8)13.3 (10.2)13.8 (10.5) MC-3500 End Cap 4.1 (3.1)4.2 (3.2)4.4. (3.3)4.5 (3.5) Note: Assumes 9” (230 mm) of separation between chamber rows and 24” (600 mm) of cover. The volume of excavation will vary as depth of cover increases. VOLUME EXCAVATION PER CHAMBER YD3 (M3) Note: Assumes 9” (230 mm) row spacing, 40% stone porosity, 12” (300 mm) stone above and includes the bare chamber/end cap volume.