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HomeMy WebLinkAboutCC - Storm Drainage Report STORM DRAINAGE REPORT AND CALCULATIONS FOR ADERO PARK SUBDIVISION NO. 2 WEST of TEN MILE and north of McMILLAN ROAD MERIDIAN, IDAHO \o r_ NSE4 PREPARED BY: 16970 CORINNE M GRAHAM, PE October 17, 2025 Csw CIVIL SIT E W O F2 K S PO BOX 6059 BOISE, ID 83707 (208) 946-3874 cgraham@cswengineering.com INTRODUCTION The existing 10.91-acre site for the Adero Park Subdivision No. 2 is currently agricultural ground.The proposed development includes 55 single family residential lots, 10 common lots, and associated public roads, landscaping, and utilities. HISTORIC DRAINAGE The existing project site north of San Vito and Vicenza Way and west of Ten Mile Road in Meridian.The McMullen lateral, an irrigation lateral owned by McMullen Lateral Water Users Association, crosses Ten Mile Road and flows west then north across the site. Historically the site drains away from the lateral to the north and south. The McMullen Lateral will be rerouted and tiled as part of the subdivision improvements. Surficial soils are comprised of silty sands with a hardpan layer at a depth of 4 feet.At depths of 6-8 feet, free draining sand and gravel with cobbles were encountered during geotechnical exploration. Groundwater was encountered at depths of 8-10 feet during geotechnical exploration and groundwater readings over the past year were logged at depths ranging from 6.8-7.7 feet. The shallow depth to groundwater limits the suitability of standard infiltration facilities.Therefore, shallow infiltration facilities are proposed to store and treat stormwater runoff. 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 80th percentile storm event. Storm water runoff from 40 feet behind the sidewalk, including residential driveways, will be conveyed to the public stormwater system to be owned and maintained by ACHD. Remaining lot drainage will be contained within individual lots. Storm water runoff for Basins#1 and #4 is conveyed via curb and gutter to drain inlets within the roadway then conveyed to infiltration basins where it is stored and infiltrated. A forebay is not required for these facilities since the required infiltration area is less than 1500 SF. Storm water runoff for Basins#2 and #3 is conveyed via curb and gutter to shallow drain inlets within the roadway then conveyed to bioretention swales between the curb and sidewalk where it is stored and infiltrated. Basin#5 storm water runoff is conveyed via curb and gutter to drain inlets within the roadway then piped to a vertical sand filter.The water quality storm event is conveyed through a sand and grease trap to the treatment bed where it is filtered through the vertical sand filter. The 100-year storm event bypasses the sand and grease trap and is conveyed directly to the percolation bed. Storm water runoff along the north side of Gondola/Malta Drive is conveyed via curb and gutter to shallow drain inlets within the roadway then conveyed to one of six bioretention swales where it is stored and infiltrated. Storm water runoff along the south side of Gondola/Malta Drive is conveyed via curb and gutter to shallow drain inlets within the roadway then conveyed to one of six bioretention swales where it is stored and infiltrated. Care will need to be taken during construction of the commercial development and frontage sidewalk to protect these systems. APPENDICES • Drainage Basin Map • Storm Drainage Calculations • Project Geotechnical Report I I I m , BASIN #3 BASIN #1 i 7 7 7 BASIN 1 BASIN 8F 1 BASIN #2 , # 1 1 #7C BASIN 8E 1 ..I # 1 BASIN #4 so 1 • � I I 1 � 00 .I 1 4f #713 1 #7A -=_____________-__ 00 00 BASIN #8D BASIN #5 BASIN #8C � ♦ , I '✓ #6B .� I BASIN #8 B 1 1 I ��I I 1 I 1 I 1 1 I #6A BASIN #8A � I i IV 0 35 70 140 210 ADERO PARK SUBDIVISION NO. 2 1—, 1X/1 L S ITE w o R K s DRAINAGE BASIN MAP SCALE: 1 = 70 PO BOX 6059 BOISE, ID 83707 Ph: (208) 946-3874 cgraham@cswengineering.com Prepared By: Corinne Graham, PE August 28, 2025 CIVIL S I T E Adero Park Subdivision No. 1 Storm Drainage Calculations C Values Impervious=0.90 Landscape=0.20 ACHD ACHD ACHD ACHD ACHD Basin#1 Basin#2 Basin#3 Basin#4 Basin#5 Total Area (SF) 48738 33492 20839 111687 54635 Roadway Area (SF) 11593 9945 5568 28490 22642 Sidewalk Area (SF) 4163 3150 1864 9871 6536 House/Driveway Area (SF) 18512 10777 6892 38791 7153 Landscape Area (SF) 14470 9620 6515 34535 18304 C Value: 0.69 0.70 1 0.68 0.68 0.67 Catch Basin Calculations CB#1A CB#16 CB#4A CB#46 CB#sA CB#513 Total Area (SF) 24995 23743 31622 80065 31037 23598 Roadway Area (SF) 5609 5984 6821 21669 13092 9550 Sidewalk Area (SF) 2076 2087 2561 7310 3244 3292 House/Driveway Area (SF) 10707 7805 14784 24007 3637 3516 Landscape Area (SF) 6603 7867 7456 27079 11064 7240 C Value: 0.72 0.67 0.73 0.66 0.65 0.69 Prepared By: Corinne Graham, PE October 17, 2025 C I V I L S I T E Adero Park Subdivision No. 1 Storm Drainage Calculations C Values Impervious=0.90 Landscape=0.20 ACHD ACHD ACHD ACHD ACHD ACHD ACHD ACHD ACHD ACHD ACHD Basin ACHD Basin#6A Basin#66 Basin#7A Basin#76 Basin#7C Basin#71D Basin#8A Basin#86 Basin#8C Basin#81D #8E Basin#8F Total Area (SF) 13052 14304 15629 6218 21918 12529 10168 13143 11956 4656 13479 11960 Roadway Area (SF) 3774 4439 4000 1761 5597 4288 4774 7113 6841 1908 5596 7428 Sidewalk Area (SF) 2698 3475 3273 1289 4204 3457 3150 3371 2834 1541 4399 2555 Landscape Area (SF) 6580 6390 8356 3168 12117 4784 2244 2659 2281 1207 3484 1977 C Value: 0.55 0.59 0.53 0.54 0.51 0.63 0.75 0.76 0.77 0.72 0.72 0.78 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 11,593 4,163 18,512 14,470 Acres 1.12 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.69 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 2.00 2.00 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 2,677 2,677 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 948 948 ft' 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 268 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 2,409 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 2,677 2,677 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 3 Phi 9/2/2025,3:52 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#1 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.69 Link to: #REF! 4 Area A(Acres) 1.12 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 2,677 2676.51 ft3 #REF! 6 Length of Swale 72 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 10.00 ft 9 Set Swale Bottom Width b 10.00 ft 10 Set Swale Top Width 25.00 ft 11 Set Swale Depth y 2.50 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 43.75 43.75 ftz Axs=Y zz+by 14 Total Swale Capacity Without Driveways 3,150 3150.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 22.3 22.30 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 39W2025,3:53 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 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 9,945 3,150 10,777 9,620 Acres 0.77 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" 9 Calculate the Post-Development peak discharge(Q Business Peak) QPeA 1.39 1.39 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,857 1,857 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 658 658 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 186 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 1,672 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 1,857 1,857 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 3 Phi 9/2/2025,3:52 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#2 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.70 Link to: #REF! 4 Area A(Acres) 0.77 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 1,857 1857.23 ft3 #REF! 6 Length of Swale 216 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 12.00 ft 11 Set Swale Depth y 1.50 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 9.75 9.75 ftz Axs=Y zz+by 14 Total Swale Capacity Without Driveways 2,106 2106.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 25.8 25.79 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 39W2025,3:53 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 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 5,568 1,864 6,892 6,515 Acres 0.48 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 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 0.84 0.84 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 1,126 1,126 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, 399 399 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 113 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 1,014 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 1,126 1,126 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 3 Phi 9/2/2025,3:52 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#3 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.68 Link to: #REF! 4 Area A(Acres) 0.48 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 1,126 1126.18 ft3 #REF! 6 Length of Swale 88 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 14.00 ft 11 Set Swale Depth y 2.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 16.00 16.00 ftz Axs=Y zz+by 14 Total Swale Capacity Without Driveways 1,408 1408.00 ft3 15 Does it Have Capacity? OK 16 Time to Drain 38.4 38.39 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 39W2025,3:53 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 Basin#4 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 28,490 9,871 38,791 34,535 Acres 2.56 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 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 4.52 4.52 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 6,057 6,057 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, 2,145 2,145 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 606 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 5,451 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 6,057 6,057 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 3 Phi 9/2/2025,3:52 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#4 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.68 Link to: #REF! 4 Area A(Acres) 2.56 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 6,057 6057.03 ft3 #REF! 6 Length of Swale 86 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 15.00 ft 9 Set Swale Bottom Width b 15.00 ft 10 Set Swale Top Width 39.00 ft 11 Set Swale Depth y 3.00 ft 12 Swale Side Slopes H:1 Sxs 4.00 13 Calculate cross-sectional area Axs 81.00 81.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 6,966 6966.00 ft3 15 Does it Have Capacity? OK 16 Time to Drain 28.2 28.17 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 39W2025,3:53 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 Basin k5 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 22,642 6,536 7,153 18,304 Acres 1.25 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.67 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 2.15 2.15 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 2,885 2,885 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, 1,022 1,022 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 288 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 2,596 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 2,885 2,885 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-Vertical Sand Filter 3 Phi 9/2/2025,3:52 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#5 Enter number of Seepage Beds(25 max) 1 Design Storm Unlined Side 100 100 Design Storm Lined Side 2 #REF! #REF! Weighted Runoff Coefficient C 0.67 Link to: #REF! Area A(Acres) 1.25 acres #REF! #REF! Approved discharge rate(if applicable) 0.00 cfs 100 Year Storm Volume V 2,885 ftA3 2 Year Storm Volume V2 781 ftA3 Width of Unlined Side W 18.0 18 ft Width of Lined Side W2 5.0 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 2.00 in/hr Size of Perf Pipe(Perf 3600) Dia pipe 18 in Design Length of Unlined Side L 100 100 Design Length of Lined Side L 98 100 ft Time to Drain Unlined Side 8.6 hours 90%volume in 48-hours minimum - Length of WQ&Overflow Perf Pipes 100 100 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#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 3,774 2,698 6,580 Acres 0.30 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.55 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 0.42 0.42 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 567 567 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, 201 201 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 57 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 510 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 567 567 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:53 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#6A 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.55 Link to: #REF! 4 Area A(Acres) 0.30 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 567 566.54 ft3 #REF! 6 Length of Swale 148 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 740 740.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 11.5 11.48 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:54 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 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 4,439 3,475 6,390 Acres 0.33 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.59 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) Qpe k 0.50 0.50 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 666 666 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, 236 236 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 67 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 600 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 666 666 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:53 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#6B 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.59 Link to: #REF! 4 Area A(Acres) 0.33 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 666 666.49 ft3 #REF! 6 Length of Swale 161 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 805 805.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 12.4 12.42 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:54 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 Basin#7A 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 4,000 3,273 8,356 Acres 0.36 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.53 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 0.49 0.49 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 652 652 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, 231 231 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 65 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 587 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 652 652 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:53 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#7A 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.53 Link to: #REF! 4 Area A(Acres) 0.36 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 652 651.92 ft3 #REF! 6 Length of Swale 132 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 660 660.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 14.8 14.82 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:54 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 Basin#76 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 1,761 1,289 3,168 Acres 0.14 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.54 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 0.20 0.20 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 268 268 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, 95 95 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 27 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 241 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 268 268 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:53 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#7B 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.54 Link to: #REF! 4 Area A(Acres) 0.14 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 268 268.05 ft' #REF! 6 Length of Swale 150 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 750 750.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 5.4 5.36 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:54 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 Basin#7C 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 5,597 4,204 12,117 Acres 0.50 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.51 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 0.67 0.67 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 892 892 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, 316 316 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 89 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 803 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 892 892 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:53 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#7C 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.51 Link to: #REF! 4 Area A(Acres) 0.50 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 892 892.11 ft3 #REF! 6 Length of Swale 211 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 1,055 1055.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 12.7 12.68 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:54 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 Basin#713 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 4,288 3,457 4,784 Acres 0.29 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.63 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 0.47 0.47 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 629 629 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, 223 223 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 63 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 566 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 629 629 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:53 PM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#71D 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.63 Link to: #REF! 4 Area A(Acres) 0.29 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 629 628.94 ft3 #REF! 6 Length of Swale 126 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 630 630.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 15.0 14.97 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 9/2/2025,3:54 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 Basin#8A 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 4,774 3,150 2,244 Acres 0.23 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.75 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 0.45 0.45 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 601 601 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, 213 213 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 60 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 541 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 601 601 ft' Roofs 0. 95 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:00 AM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#8A 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.75 Link to: #REF! 4 Area A(Acres) 0.23 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 601 601.42 ft3 #REF! 6 Length of Swale 178 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 890 890.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 10.1 10.14 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:01 AM 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 Basin#86 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 7,113 3,371 2,659 Acres 0.30 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.76 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 0.59 0.59 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 791 791 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, 280 280 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 79 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 712 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 791 791 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:00 AM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#8B 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.76 Link to: #REF! 4 Area A(Acres) 0.30 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 791 790.80 ft3 #REF! 6 Length of Swale 230 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 1,150 1150.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 10.3 10.31 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:01 AM 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 Basin#8C 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 6,841 2,834 2,281 Acres 0.27 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.77 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 Tciiiiiiiiiiiiii 2.58 in hr Type of Surface Runoff Coefficients" Business 9 Calculate the Post-Development peak discharge(QPeak) Qpeak 0.54 0.54 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 727 727 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, 257 257 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 73 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 654 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 727 727 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:00 AM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#8C 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.77 Link to: #REF! 4 Area A(Acres) 0.27 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 727 727.04 ft3 #REF! 6 Length of Swale 184 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 920 920.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 11.9 11.85 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:01 AM 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 Basin#813 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 1,908 1,541 1,207 Acres 0.11 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.72 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 0.20 0.20 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 265 265 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, 94 94 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 27 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 239 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 265 265 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:00 AM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#8D 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.72 Link to: #REF! 4 Area A(Acres) 0.11 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 265 265.43 ft3 #REF! 6 Length of Swale 150 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 750 750.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 5.3 5.31 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:01 AM 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 Basin#8E 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 5,596 4,399 3,484 Acres 0.31 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.72 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 0.57 0.57 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 769 769 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, 272 272 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 77 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 692 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 769 769 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:00 AM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#8E 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.72 Link to: #REF! 4 Area A(Acres) 0.31 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 769 768.98 ft3 #REF! 6 Length of Swale 237 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 1,185 1185.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 9.7 9.73 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:01 AM 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 Basin#8F 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 7,428 2,555 1,977 Acres 0.27 6 Determine the Weighted Runoff Coefficient(C) 0.90 0.90 0.20 C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 0.78 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 Tciiiiiiiiiiiiii 2.58 in hr Type of Surface Runoff Coefficients" Business 9 Calculate the Post-Development peak discharge(QPeak) Qpeak 0.56 0.56 cfs Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 10 Calculate total runoff vol(V)(for sizing primary storage) V 744 744 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, 264 264 ff' 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 74 ft' Streets Asphalt 0.95 Primary Treatment/StorageBasin V 670 ft' Concrete 0.95 Subsurface Storage Brick 0.95 Volume Without Sediment Factor(See BMP 20 Tab) V 744 744 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\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:00 AM Version 10.5,November 2018 ACHD Calculation Sheet for Sizing Bioswales & Borrow Ditches #REF! #REF! 1 Project Name ACHD Basin#8E 2 Enter number of Bioswales/Borrow Ditches(25 max) 1 3 Design Storm 100 Weighted Runoff Coefficient C 0.78 Link to: #REF! 4 Area A(Acres) 0.27 acres #REF! Approved discharge rate for the given storm(if applicable) 0.00 cfs #REF! 5 Design Vol With 0%Sed for Swales V 744 744.21 ft' #REF! 6 Length of Swale 165 ft 7 Infiltration Window?(Note:infiltration required if Longitudinal Sloped%) Design Infiltration Rate 2.00 in/hr 8 Infiltration Window Width 2.00 ft 9 Set Swale Bottom Width b 2.00 ft 10 Set Swale Top Width 8.00 ft 11 Set Swale Depth y 1.00 ft 12 Swale Side Slopes H:1 Sxs 3.00 13 Calculate cross-sectional area Axs 5.00 5.00 ft' Axs=Y zz+by 14 Total Swale Capacity Without Driveways 825 825.00 ft' 15 Does it Have Capacity? OK 16 Time to Drain 13.5 13.53 hr 90%volume in 48-hours minimum OK C:\Users\cgrah\Dropbox\Projects\23007 Adero Park Subdivision\Reports\Storm Drainage\Storm Drain Calc-ACHD Swales 10/17/2025,10:01 AM Version 10.0,May 2018