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Home My WebLink AboutCC - Storm Drainage Calcs STORM DRAINAGE REPORT AND CALCULATIONS FOR AVANI SUBDIVISION NO. 1 S. BLACK CAT ROAD, MERIDIAN, IDAHO \o r_ NSE4 PREPARED BY: a 16970 CORINNE M GRAHAM, PE June 12, 2024 csw C I V I L S I T E W O F2 K S PO BOX 6059 BOISE, ID 83707 (208) 946-3874 cgraham@cswengineering.com INTRODUCTION The existing 11.88-acre site for the proposed Avani Subdivision No. 1 is currently vacant ground.The proposed development includes 68 single family residential lots, 10 landscape common lots, and associated public streets, storm drain facilities, landscaping, and utilities. HISTORIC DRAINAGE The existing project site sits east of S Black Cat Road approximately% mile south W. Franklin Road in Meridian.The Rosenlof Drain, a Nampa Meridian Irrigation District facility,transverses half of the site from southeast to northwest. Surficial soils are comprised of lean clay with sand.At depth, sandy silt and poorly graded gravel with sand was encountered during geotechnical exploration. Groundwater was encountered at depths as shallow as 7.6 feet below existing ground surface.According to the project geotechnical report, high seasonal groundwater elevations are anticipated at 3.5 feet below ground surface but ongoing monitoring is expected to show the seasonal high groundwater level is deeper than this. Because of the presence of free draining materials and the depth to groundwater,the site is suitable for the use of shallow infiltration facilities. PROPOSED DRAINAGE The storm drainage calculations and design for the proposed improvements are intended to meet the requirements of ACHD's storm water policy. Storm water facilities are designed to store and treat runoff from a 100-year storm event and to pretreat the water quality volume defined as the 801" percentile storm event. Storm water runoff from 40' behind the sidewalk, including residential driveways, will be conveyed to the public stormwater system to be owned and maintained by ACHD. Runoff from the private alleys and the driveways for the alley-loaded homes will be directed to a private drainage facility (Private Basins#4P and #513). Remaining lot drainage will be contained within individual lots. Stormwater runoff from the public streets is conveyed via curb and gutter to drain inlets within the roadway then piped to one of three vertical sand filters where it is treated, stored, and finally infiltrated. A sand and grease trap will be installed to provide pre-treatment for the water quality event with a bypass manhole provided for larger storm events. APPENDICES • Drainage Basin Map • Storm Drainage Calculations • Project Geotechnical Report I I I I I I I I I I I I I ' TEMP I I i 1 BASIN #6B - - BASIN #2 - BASIN #3 ; TEMP ION mm 1 BASIN #6A 1 1 1 1 I , 1 1 1 1 I I 1 1 1 1 1 1 I BASIN #4P BASIN #5P 1 I i 1 1 1 1 1 1 1 I I 1 1 I M BASIN - _ BASIN #1 _ - - _ � � - 00 I I I I I , I I I N csw �Iw o�Rs STE so o so ioo AVANI SUBDIVISION NO. 1 PO BOX 6059 DRAINAGE BASIN MAP SCALE: 1" = 100' BOISE,ID 83707 Ph: (208)946-3874 cgraham@cswengineering.com Prepared By: Corinne Graham, PE Date:June 12, 2024 G IVI L S ITE Avani Subdivision No. 1 Storm Drainage Calculations C Values Impervious=0.90 Landscape=0.20 Private Basin Private Basin ACHD Temp ACHD Temp ACHD Basin#1 ACHD Basin#2 ACHD Basin#3 #4P #5113 Basin#6A Basin#6B Total Area (SF) 94725 55376 92804 17202 17334 20235 25911 Roadway Area (SF) 28053 16349 27134 5540 5540 4086 7759 Sidewalk Area (SF) 7243 4758 8111 0 0 1524 2462 House/Driveway Area (SF) 27260 18253 25620 6977 6977 8331 5319 Landscape Area (SF) 32169 16016 31939 4685 4817 6294 10371 C Value: 0.66 0.70 0.66 0.71 0.71 0.68 0.62 Catch Basin Calculations CB#1A CB#1B CB#2A CB#2B CB#3A CB#3B Total Area (SF) 25989 68736 37848 17528 69639 23165 Roadway Area (SF) 7009 21044 11305 5044 20818 6316 Sidewalk Area (SF) 2332 4911 2873 1885 5939 2172 House/Driveway Area (SF) 8400 18860 12137 6116 18877 6743 Landscape Area (SF) 8248 23921 11533 4483 24005 7934 C Value: 0.68 0.66 0.69 0.72 0.66 0.66 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. for Peak Discharge Rate using th r post-developm Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name ACHD Basin k1 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins ❑ Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 27,782 7,243 27,260 32,440 Acres 2.17 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.66 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate 10 Min. Estimated Runoff Coefficients for Various Surfac 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc 2.58 2.58 in hr Type of Surface Runoff Coefficients" 9 Calculate the Post-Development peak discharge(Q Business Peak) Qp-k 3.70 3.70 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 4,962 4,962 ft Residential Single Family 0.35-0.50 V=Ci(Tc=60)Ax3600 Multi-family 0.60-0.75 11 Calculate Volume of Runoff Reduction Vrr Residential(rural) 0.25-0.40 Apartment Dwelling Areas 0.70 Enter Percentile Storm I(95th percentile=0.60 in) 80th 0.34 in Industrial and Commercial Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr, 1,757 1,757 W fight areas 0.80 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) 0.00 cfs Heavy areas 0.90 Parks,Cemeteries 0.10-0.25 Playgrounds 0.20-0.35 13 Volume Summary Railroad yard areas 0.20-0.40 Surface Storage:Basin Unimproved areas 0.10-0.30 Basin Forebay V 496 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 4,466 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 4,962 4,962 ft' Roofs 0.95 Gravel 0.75 Fields:Sandy soil Soil Type Slope A B C fl' .. Flat:O-2% 0.04 0.07Average:2-6% 0.09 0.12 0Steep:>6% 0.13 0.18 0 Adapted from ASCE C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 3 6/12/2024,4:43 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Vertical Sand Filters #REF! Note this spreadsheet pulls information from the"Peak CI"V"tab #REF! #REF! Project Name ACHD Basin#1 Enter number of Seepage Beds(25 max) 1 Design Storm Unlined Side 100 #REF! Design Storm Lined Side 2 #REF! #REF! Weighted Runoff Coefficient C 0.66 Link to: #REF! Area A(Acres) 2.17 acres #REF! #REF! Approved discharge rate(if applicable) 0.00 cfs 100 Year Storm Volume V 4,962 ftA3 2 Year Storm Volume V2 1,344 ftA3 Width of Unlined Side W 15.0 28 ft Width of Lined Side W2 7.5 Depth of Unlined Side D 4.0 ft Depth of Lined Side D2 4.0 ft Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips Design Infiltration Rate(8 in/hr max) Perc 1.00 in/hr Size of Perf Pipe(Perf 3600) Dia pipe 18 in Design Length of Unlined Side L 112 111 Design Length of Lined Side L 112 112 ft Time to Drain Unlined Side 17.3 hours 90%volume in 48-hours minimum OK Length of WQ&Overflow Perf Pipes 112 112 ft Perf Pipe Checks.Qperf>=Qpeak; #REF! where Qperf=CdxAxV(2xgxH) ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. for Peak Discharge Rate using th r post-developm Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name ACHD Basin#2 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins ❑ Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 16,349 4,758 18,253 16,016 Acres 1.27 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.70 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate 10 Min. Estimated Runoff Coefficients for Various Surfac 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc 2.58 2.58 in hr Type of Surface Runoff Coefficients" y Calculate the Post-Development peak discharge(Q Business Peak) Qp-k 2.29 2.29 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 3,065 3,065 ft Residential Single Family 0.35-0.50 V=Ci(Tc=60)Ax3600 Multi-family 0.60-0.75 11 Calculate Volume of Runoff Reduction Vrr Residential(rural) 0.25-0.40 Apartment Dwelling Areas 0.70 Enter Percentile Storm I(95th percentile=0.60 in) 80th 0.34 in Industrial and Commercial Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr, 1,085 1,085 W fight areas 0.80 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) 0.00 cfs Heavy areas 0.90 Parks,Cemeteries 0.10-0.25 Playgrounds 0.20-0.35 13 Volume Summary Railroad yard areas 0.20-0.40 Surface Storage:Basin Unimproved areas 0.10-0.30 Basin Forebay V 306 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 2,758 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 3,065 3,065 ft' Roofs 0. Gravel 0.7575 Fields:Sandy soil Soil Type Slope A B C fl' .. Flat:O-2% 0.04 0.07Average:2-6% 0.09 0.12 0Steep:>6% 0.13 0.18 0 Adapted from ASCE C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 3 6/12/2024,4:43 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Vertical Sand Filters #REF! Note this spreadsheet pulls information from the"Peak CI"V"tab #REF! #REF! Project Name ACHD Basin#2 Enter number of Seepage Beds(25 max) 1 Design Storm Unlined Side 100 #REF! Design Storm Lined Side 2 #REF! #REF! Weighted Runoff Coefficient C 0.70 Link to: #REF! Area A(Acres) 1.27 acres #REF! #REF! Approved discharge rate(if applicable) 0.00 cfs 100 Year Storm Volume V 3,065 ftA3 2 Year Storm Volume V2 830 ftA3 Width of Unlined Side W 15.0 15 ft Width of Lined Side W2 4.0 Depth of Unlined Side D 4.0 ft Depth of Lined Side D2 4.0 ft Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips Design Infiltration Rate(8 in/hr max) Perc 1.00 in/hr Size of Perf Pipe(Perf 3600) Dia pipe 18 in Design Length of Unlined Side L 130 128 Design Length of Lined Side L 130 130 ft Time to Drain Unlined Side 17.3 hours 90%volume in 48-hours minimum OK Length of WQ&Overflow Perf Pipes 130 130 ft Perf Pipe Checks.Qperf>=Qpeak; #REF! where Qperf=CdxAxV(2xgxH) ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. for Peak Discharge Rate using th r post-developm Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name ACHD Basin#3 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins ❑ Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 27,134 8,111 25,620 31,939 Acres 2.13 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.66 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate 10 Min. Estimated Runoff Coefficients for Various Surfac 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc 2.58 2.58 in hr Type of Surface Runoff Coefficients" y Calculate the Post-Development peak discharge(Q Business Peak) Qp-k 3.62 3.62 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 4,853 4,853 ft Residential Single Family 0.35-0.50 V=Ci(Tc=60)Ax3600 Multi-family 0.60-0.75 11 Calculate Volume of Runoff Reduction Vrr Residential(rural) 0.25-0.40 Apartment Dwelling Areas 0.70 Enter Percentile Storm I(95th percentile=0.60 in) 80th 0.34 in Industrial and Commercial Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr, 1,719 1,719 W fight areas 0.80 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) 0.00 cfs Heavy areas 0.90 Parks,Cemeteries 0.10-0.25 Playgrounds 0.20-0.35 13 Volume Summary Railroad yard areas 0.20-0.40 Surface Storage:Basin Unimproved areas 0.10-0.30 Basin Forebay V 485 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 4,368 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 4,853 4,853 ft' Roofs 0.95 Gravel 0.75 Fields:Sandy soil Soil Type Slope A B C fl' .. Flat:O-2% 0.04 0.07Average:2-6% 0.09 0.12 0Steep:>6% 0.13 0.18 0 Adapted from ASCE C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 3 6/12/2024,4:43 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Vertical Sand Filters #REF! Note this spreadsheet pulls information from the"Peak CI"V"tab #REF! #REF! Project Name ACHD Basin#3 Enter number of Seepage Beds(25 max) 1 Design Storm Unlined Side 100 #REF! Design Storm Lined Side 2 #REF! #REF! Weighted Runoff Coefficient C 0.66 Link to: #REF! Area A(Acres) 2.13 acres #REF! #REF! Approved discharge rate(if applicable) 0.00 cfs 100 Year Storm Volume V 4,853 ftA3 2 Year Storm Volume V2 1,314 ftA3 Width of Unlined Side W 20.0 20 ft Width of Lined Side W2 5.5 Depth of Unlined Side D 4.0 ft Depth of Lined Side D2 4.0 ft Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips Design Infiltration Rate(8 in/hr max) Perc 1.00 in/hr Size of Perf Pipe(Perf 3600) Dia pipe 18 in Design Length of Unlined Side L 152 152 Design Length of Lined Side L 149 152 ft Time to Drain Unlined Side 17.3 hours 90%volume in 48-hours minimum OK Length of WQ&Overflow Perf Pipes 152 152 ft Perf Pipe Checks.Qperf>=Qpeak; #REF! where Qperf=CdxAxV(2xgxH) ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. for Peak Discharge Rate using th r post-developm Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name Private Basin q4P 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins ❑ Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 5,540 0 6,977 4,685 Acres 0.39 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.71 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 Min. I Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients"I 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 2.58 in hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) Qpe k 0.72 0.72 cfs Urban neighborhoods 0.50-0.70 Residential 50 10 Calculate total runoff vol V for sizing rims storage) V 968 968 ft Single Family 0.60-0.75 ( )( g primary g ) Multi-family 0.60-0.75 V=Ci(Tc=60)Ax3600 Residential(rural) 0.25-0.40 11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70 Industrial and Commercial Enter Percentile Storm I(95th percentile=0.60 in) 80th 0.34 in Light areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr, 343 343 ff' Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) 0.00 cfs Parks,cemeteries 0. Playgrounds 0.20-0.0-0.35 5 Railroad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 095 Basin Foreba V 97 ft' . Y Concrete 0.95 Primary Treatment/StorageBasin V 871 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 968 968 ft' Gravel 0.75 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 0. Adapted from ASCE C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\ACHD_SD_CALCS_112723 6/12/2024,4:44 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Note this spreadsheet pulls information from the"Peak QV"tab _ steps�Beds Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name Private Basin#4P 2 Enter number of Seepage Beds(25 max) 1 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.71 Link to: Q.V(4) QV TR55 5 Area A(Acres) 0.39 acres 6 Approved discharge rate(if applicable) 0.00 cfs 7 Is Seepage Bed in Common Lot? Yes V 968 968 ft3 0%Sediment 8 Set Total Design Width of All Drain Rock W 3.0 ft 9 Set Total Design Depth of All Drain Rock D 3.0 ft Rock Only,Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips 11 Design Infiltration Rate(8 in/hr max) Perc 8.00 in/hr 12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 3600),READ if Q100>3.3 cfs 12 in 14 Calculate Total Storage per Foot Spf 6.2 ft3/ft 15 Calculate Design Length L 0 152 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 152 152.0 ft 17 Variable Infiltration Window W SWW 3.0 3.0 ft 18 Time to Drain 2.9 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 152 152 ft 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAxJ(2xgxH) C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\ACHD_SD_CALCS_112723 6/12/2024,4:44 PM Version 10.0,May 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. for Peak Discharge Rate using th r post-developm Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name Private Basin#5P 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins ❑ Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 5,540 0 6,977 4,817 Acres 0.40 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.71 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 Min. I Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients"I 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 2.58 in hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(QPeak) Qpe k 0.72 0.72 cfs Urban neighborhoods 0.50-0.70 Residential 50 10 Calculate total runoff vol V for sizing rims storage) V 970 970 ft Single Family 0.60-0.75 ( )( g primary g ) Multi-family 0.60-0.75 V=Ci(Tc=60)Ax3600 Residential(rural) 0.25-0.40 11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70 Industrial and Commercial Enter Percentile Storm I(95th percentile=0.60 in) 80th 0.34 in Light areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr, 344 344 ft' Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) 0.00 cfs Parks,cemeteries 0. Playgrounds 0.20-0.0-0.35 5 Railroad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 095 Basin Foreba V 97 ft' . Y Concrete 0.95 Primary Treatment/StorageBasin V 873 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 970 970 ft' Gravel 0.75 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 0. Adapted from ASCE C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\ACHD_SD_CALCS_112723 6/12/2024,4:44 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. Note this spreadsheet pulls information from the"Peak QV"tab Steps�Beds Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name Private Basin#5P 2 Enter number of Seepage Beds(25 max) 1 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.71 Link to: Q.V(4) QV TR55 5 Area A(Acres) 0.40 acres 6 Approved discharge rate(if applicable) 0.00 cfs 7 Is Seepage Bed in Common Lot? Yes V 970 970 ft' 0%Sediment 8 Set Total Design Width of All Drain Rock W 3.0 ft 9 Set Total Design Depth of All Drain Rock D 3.0 ft Rock Only,Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 0.4 for 1.5"-2"drain rock and 3/4"Chips 11 Design Infiltration Rate(8 in/hr max) Perc 8.00 in/hr 12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe(Perfs 3601),READ if Q100>3.3 cfs 12 in 14 Calculate Total Storage per Foot Spf 6.2 ft3/ft 15 Calculate Design Length L 0 152 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 152 152.0 ft 17 Variable Infiltration Window W SWW 3.0 3.0 ft 18 Time to Drain 2.9 hours 90%volume in 48-hours minimum 19 Length of WQ&Overflow Perf Pipes 152 152 ft 20 Perf Pipe Checks.Qperf>=Qpeak; where Qperf=CdxAxJ(2xgxH) C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\ACHD_SD_CALCS_112723 6/12/2024,4:44 PM Version 10.0,May 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. for Peak Discharge Rate using th r post-developm Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name ACHD Temp Basin#6A 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins ❑ Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 4,086 1,524 8,331 6,294 Acres 0.46 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.68 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 Min. I Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients"I 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 2.58 in hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(ClPeak) DPeA 0.82 0.82 cfs Urban neighborhoods 0.50-0.70 Residential 50 10 Calculate total runoff vol V for sizing rims storage) V 1,095 1,095 ft Single Family 0.60-0.75 ( )( g primary g ) Multi-family 0.60-0.75 V=Ci(Tc=60)Ax3600 Residential(rural) 0.25-0.40 11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70 Industrial and Commercial Enter Percentile Storm I(95th percentile=0.60 in) 80th 0.34 in Light areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr, 388 388 ff' Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) 0.00 cfs Parks,cemeteries 0. Playgrounds 0.20-0.0-0.35 5 Railroad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 095 Basin Foreba V 110 ft' . Y Concrete 0.95 Primary Treatment/StorageBasin V 986 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 1,095 1,095 ft' Gravel 0.75 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 0. Adapted from ASCE C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\ACHD_SD_CALCS_112723 6/12/2024,4:44 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. User input in yellow cells. 1 Project Name ACHD Temp Basin#6A 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.68 Link to LQV(4) 4 Area A(Acres) 0.46 acres Q,V TRSS Approved discharge rate for the given storm(if applicable) 0.00 cfs 5 Design Vol With 0%Sed for Swales V 1,095 1095 ft3 6 Length of Swale 56 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 4.00 ft 9 Set Swale Bottom Width b 4.00 ft 10 Set Swale Top Width 20.00 ft 11 Set Swale Depth y 2.00 ft 12 Swale Side Slopes H:1 Sxs 4.00 13 Calculate cross-sectional area Axs 24.00 24.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 1,344 1344.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 29.3 29.34 hr 90%volume in 48-hours minimum OK Check Borrow Ditch Infiltration Windows 17 Enter Infiltration Window Length 40.00 ft 18 Enter Infiltration Window Width 4 If 19 Time to Drain 45.6 45.6 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\ACHD_SD_CALCS_112723 6/12/2024,4:45 PM Version 10.0,May 2018 ACHD Calculation Sheet for Finding Peak Discharge/Volume-Rational Method NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology.These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. for Peak Discharge Rate using th r post-developm Calculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab) User input in yellow cells. 1 Project Name ACHD Temp Basin#613 2 Is area drainage basin map provided? YES (map must be included with stormwater calculations) 3 Enter Design Storm(100-Year or 25-Year With 100-Year Flood Route) 100 4 Enter number of storage facilities(25 max) Click to Show More Subbasins ❑ Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 Subbasin 6 7 8 9 10 5 Area of Drainage Subbasin(SF or Acres) SF 7,759 2,462 5,319 10,371 Acres 0.59 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.62 7 Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 User Calculate min 10 Min. I Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients"I 8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 2.58 in hr Business Downtown areas 0.70-0.95 9 Calculate the Post-Development peak discharge(ClPeak) DPeA 0.95 0.95 cfs Urban neighborhoods 0.50-0.70 Residential Single Family 0.35-0.50 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,274 1,274 ft Multi-family 0.60-0.75 V=Ci(Tc=60)Ax3600 Residential(rural) 0.25-0.40 11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70 Industrial and Commercial Enter Percentile Storm I(95th percentile=0.60 in) 80th 0.34 in Light areas 0.80 Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 451 451 ft' Heavy areas 0.90 12 Detention:Approved Discharge Rate to Surface Waters(if applicable) 0.00 cfs Parks,cemeteries 0. Playgrounds 0.20-0.0-0.35 5 Railroad yard areas 0.20-0.40 13 Volume Summary Unimproved areas 0.10-0.30 Surface Storage:Basin Streets Asphalt 095 Basin Foreba V 127 ft' . Y Concrete 0.95 Primary Treatment/StorageBasin V 1,147 ft' Brick 0.95 Subsurface Storage Roofs 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 1,274 1,274 ft' Gravel 0.75 Fields:Sandy soil Soil Type Slope A B C D Flat:0-2% 0.04 0.07 0.11 0. Average:2-6% 0.09 0.12 0.15 0. Steep:>6% 0.13 0.18 0.23 0. Adapted from ASCE C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\ACHD_SD_CALCS_112723 6/12/2024,4:44 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet or exceed these calculations in order to be accepted. User input in yellow cells. 1 Project Name ACHD Temp Basin#6B 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.62 Link to LQV(4) 4 Area A(Acres) 0.59 acres Q,V TRSS Approved discharge rate for the given storm(if applicable) 0.00 cfs 5 Design Vol With 0%Sed for Swales V 1,274 1274 ft' 6 Length of Swale 56 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 4.00 ft 9 Set Swale Bottom Width b 4.00 ft 10 Set Swale Top Width 20.00 ft 11 Set Swale Depth y 2.00 ft 12 Swale Side Slopes H:1 Sxs 4.00 13 Calculate cross-sectional area Axs 24.00 24.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 1,344 1344.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 34.1 34.13 hr 90%volume in 48-hours minimum OK Check Borrow Ditch Infiltration Windows 17 Enter Infiltration Window Length 45.00 ft 18 Enter Infiltration Window Width 4 If 19 Time to Drain 47.2 47.2 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\19005 Avani Subdivision\Reports\Storm Drainage\ACHD_SD_CALCS_112723 6/12/2024,4:45 PM Version 10.0,May 2018