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Home My WebLink AboutCC - Drainage Calcs2775 W. Navigator Dr, Suite 210 H O RRO C K S Tel: Meridian Office Meridian, ID 83642 208 895-2520 www.horrocks.com "," E N G I N E E R S Drainage Report Rackham Subdivision Common and Public Improvements 1330 S. Silverstone Way Meridian, Idaho HE Project No.: ID -1836-1808 October 28, 2019 Rob Sunderlage PE Horrocks Engineers Horrocks Engineers Introduction This project consists of constructing ±3,715 If of new roadway as well as associated water, sanitary sewer, and drainage improvements to support the proposed ±52.71 ac development within the Rackham Subdivision. The project is located southeast of the intersection of Interstate 84 and Eagle Road in Meridian Idaho. It is served on the southwest corner by S. Rackham Way and on the south by S. Silverstone Way. The project has three main roads referred to as "Road A", "Road B" and "Road C' in both this report and the Public Improvement Plans. Each road is served with its own storm drain system, sand and grease trap, and infiltration bed. Storm eater Inputs The storm design for the site was completed using the "ACRD Calculation Sheet for Finding Peak Discharge/Volume — Rational Method" & the "ACHD Calculation Sheet for Sizing Seepage Bed with Optional Chambers" calculation sheets. Weighted C values were calculated for each drainage area using a C value of 0.95 for paved areas and 0.30 for landscape areas. Since the drainage areas are relatively small the default time of concentration of 10 minutes was used. An infiltration rate of 2.40 in/hr was assumed per the geotechnical report published on December 18th 2018 by MTI (b181762g). Each infiltration bed drains within the required time at this infiltration rate with the slowest draining bed draining in just under 14 hours. Drainage Area OFS-1 (see appendix) is included in the ICCU Building drainage system. Please reference the drainage report prepared as part of the ICCU project for more information on this. The ACHD roundabout has its own drainage system and infiltration bed. Please reference the drainage report for prepared for the roundabout for any information pertaining to it. As part of this project three infiltration swales will be installed along the western property line. These are not needed to handle the runoff from the proposed roadways; however, they are being installed for future connection when the site is developed. A drainage report will be prepared for each one of these with each development that utilizes the capacity in these swales. Storm Water Design Results Refer to Appendix A for Drainage Area Map and Appendix B for Drainage Calculations and design results. Hc)rroc-hs Engineers Appendix A: Drainage Area Map Horrocks Engineers Appendix B: Drainage Calculations Horrocks Engineers ACRD 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. calculate Post -Development Flows {for pre-developmentflows, Increase number of storage facilities to create new tab) User Input in yellow cells, 1 Project Name Seepage Bed Al 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) 5 Area of Drainage Subbasin (SF or Acres) Acres Acres 6 Determine the Weighted Runoff Coefficient (C) C=((C1xA1)+(C2xA2)+(CnxAn))/A Weighted Avg Click to Show More Subbasins ❑ Subbasin Type of Surface_ Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 1.00 Light areas 0.80 Heavy areas 0.90 Parks, Cemeteries 0.10-0.25 Playgrounds 0.20-0.35 Railroad yard areas 1.00 Unimproved areas 0.10-0.30 Streets Asphalt 0.95 Concrete 0.95 Brick 0.80 Roofs 0.95 Gravel 0.75 Fields: Sandy soil Soil Type Slope A B C D Flat: 0.291 0.80 Average: 2.65. 0.09 0.12 0.15 0. Stee :>69� 0.13 0.18 0.23 0. Adapted from ASCE 7 Calculate Overland Flow Time of Concentration in Minutes (Tc) or use default User Calmate 10 min [10 Mkt. J , Estimated Runoff Coefficients for Various Surfac- Type of Surface_ Runoff Coefficients 'Y Business Downtown areas 0.70-0.95 Urban nelghborhoods 0.50-0.70 Residential Single Family 0.35-0.50 Multi -family 0.60-0.75 Residential (rural) 0.25-0.40 Apartment Dwelling Areas 0.70 Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Parks, Cemeteries 0.10-0.25 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Unimproved areas 0.10-0.30 Streets Asphalt 0.95 Concrete 0.95 Brick 0.95 Roofs 0.95 Gravel 0.75 Fields: Sandy soil Soil Type Slope A B C D Flat: 0.291 0.04 0.07 0.11 0. Average: 2.65. 0.09 0.12 0.15 0. Stee :>69� 0.13 0.18 0.23 0. Adapted from ASCE H:\12018\ID-1336-1808 Eagle View Plaza\Project Data\02 CAD\2.01 Base Files\Working\Michael O\ACHD_SD_CALCS_Seepage Bed Al 10/28/2019,9:41 AM Version 9.0, December 2016 I Project Name Seepage Bed Al 2 Enter number of Seepage Beds (25 max) 1 3 Design Storm 100 4 Weighted Runoff Coefficient C 0.80 Link to: 0'Vq,vTR55 5 Area A (Acres) 1.00 acres 6 Approved discharge rate (if applicable) 0.00 cfs 7 Design Vol W/15% Sediment V 3,180 ft 8 Set Total Design Width of All Drain Rock W 25.0 ft 9 Set Total Design Depth of All Drain Rock D 7.0 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 2.40 in/hr 12 Size of WQ Perf Pipe (Perf 1800) Dia pipe 18 in 13 Size of Overflow Perf Pipe (Perls 360°), REQD if Q100>3.3 cfs in 14 Calculate Total Storage per Foot Spf 70.2 It3/ft Spf=Apf=WxD-Ap,ff_pjp,xVoids+l/2 Perf-Area 15 Calculate Design Length L 45 46 ft Override Value Required for Chambers 16 Variable Infiltration Window L SWL 46 ft 17 Variable Infiltration Window W SWW 25.0 ft 18 Time to Drain 12.4 hours 90% volume in 48 -hours minimum _ EW 19 Length of WQ& Overflow Perf Pipes 46 ft 20 Perf Pipe Checks. Qperf >= Qpeak where Qperf-CdxAxd(2xgxH) H:\!2018\ID-1336-1808 Eagle View Plaza\Project Data\02 CAD\2.01 Base Files\Working\Michael 0\ACHD_SD_CALCS_See00JbE @6M 9:44 AM Version 9.0, December 2016 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. ii ;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 Seepage Bed A2 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) 5 Area of Drainage Subbasin (SF or Acres) SF Acres 6 Determine the Weighted Runoff Coefficient (C) C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg Click to Show More Subbasins ❑ Subbasin Type of Surface Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 50,529 Light areas 0.80 Heavy areas 0.90 Parks, Cemeteries 0.10.0.25 Playgrounds 0.20-0.35 Railroad yard areas 1.16 Unimproved areas 0.10-0.30 Streets Asphalt 0.95 Concrete 0.95 Brick 0.68 Roofs 0.95 Gravel 0.75 Fields: Sandy soil Soil Type Slope A B C D Flat: 0-2% 0.68 Average: 2-6Y 0.09 0.12. 0.15 0. Stee :>6ga 0.13 0.18 0.23 0. Adapted from ASCE 7 Calculate Overland Flow Time of Concentration in Minutes (Tc) or use default User Calculate 10 min [10 Min. Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients "t Business Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0,70 Residential Single Family 0.35-0.50 Multi -family 0.60-0.75 Residential (rural) 0.25-0.40 Apartment Dwelling Areas 0.70 Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Parks, Cemeteries 0.10.0.25 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Unimproved areas 0.10-0.30 Streets Asphalt 0.95 Concrete 0.95 Brick 0.95 Roofs 0.95 Gravel 0.75 Fields: Sandy soil Soil Type Slope A B C D Flat: 0-2% 0.04 0.07 0.11 0. Average: 2-6Y 0.09 0.12. 0.15 0. Stee :>6ga 0.13 0.18 0.23 0. Adapted from ASCE H:\12018\ID-1336-1808 Eagle View Plaza\Project Data\02 CAD\2.01 Base Files\Working\Michael 0\ACHD_SD_CALCS_Seepage Bed A2 10/28/2019,9:52 AM Version 9.0, December 2016 1 Project Name Seepage Bed A2 2 Enter number of Seepage Beds (25 m 3 Design Storm 4 Weighted Runoff Coefficient C 5 Area A (Acres) 6 Approved discharge rate (if applicable) 7 Design Vol W/15%Sediment 8 Set Total Design Width of All Drain Rock 1 0.68 Link to: oV QV TR55 1.1.6 acres 0.00 cls V 3,140 It, W 15.0 It 9 Set Total Design Depth of All Drain Rock D Rock Only, Do Nlot Include Filter Sand Depth or Cover 10 Void Ratio of Drain Rock Voids 0.4 for 1.5"-2" drain rock and 3/4" Chips 7.0 ft 0.4 1.1 Design Infiltration Rate (8 in/hr max) Pere 2.40 in/hr 12 Size of WQ Perf Pipe (Perf 1.80°) Dia pipe 18 in 13 Size of Overflow Perf Pipe (Perls 360°), RLQD if Q100>3.3 cls in 14 Calculate Total Storage per Foot Spf 42.2 ft'/ft Spf=Apf=WxD-Ap,, r;Pt,xVoids i 1/2 Perf_Area 15 Calculate Design Length Override Value Required for Chambers 16 Variable Infiltration Window L 17 Variable Infiltration Window W 18 Time to Drain 90% volume in 48 -hours minimum 19 Length of WQ & Overflow Perf Pipes 20 Perf Pipe Checks. Qperf >= Qpeak; where Qperf=CdxAxV(2xgxH) L 74 75 ft SWL 75 It SWW 15.0 It 12.6 hours 75 ft H:\12018\ID-1336-1808 Eagle View Plaza\Project Data\02 CAD\2.01 Base Files\Working\Michael 0\ACHD_SD_CALCS_See0@JbE V@dK 9:53 AM Version 9.0, December 2016 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. 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 Seepage Bed B1 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) 5 Area of Drainage Subbasin (SF or Acres) SF Acres 6 Determine the Weighted Runoff Coefficient (C) C=((C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg Click to Show More Subbasins ❑ Subbasin Type of Surface Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 35,284 0 0.80 Heavy areas 0.90 Parks, Cemeteries 0.10-0.25 Playgrounds 0.20.0.35 Railroad yard areas 0.81 Unimproved areas 0.10.0.30. Streets Asphalt 0.95 Concrete 0.95 Brick 0.74 0.00 0.95 Gravel 0.75 Fields: Sandy soil Soil Type Slope A B C D Flat: 0-2% 0,7a Average: 2.6% 0.09 0.12 0.15 0, Steep:s66i, 0.13 0.18 0.23 0. Adapted from ASCE 7 Calculate Overland Flow Time of Concentration in Minutes (Tc) or use default User calculate 10 min [10 Min.-� Estimated Runoff Coefficients for Various Surfac, Type of Surface Runoff Coefficients "t Business Downtown areas 0.70-0.95 Urban neighborhoods 0,50-0.70 Residential Single Family 0.35.0.50 Multi -family 0.60.0.75 Residential (rural) 0.25.0.40 Apartment Dwelling Areas 0.70 Industrial and Commercial Llghtareas 0.80 Heavy areas 0.90 Parks, Cemeteries 0.10-0.25 Playgrounds 0.20.0.35 Railroad yard areas 0.20-0.40 Unimproved areas 0.10.0.30. Streets Asphalt 0.95 Concrete 0.95 Brick 0.95 Roofs 0.95 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:s66i, 0.13 0.18 0.23 0. Adapted from ASCE H:\12018\ID-1336-1808 Eagle View Plaza\Project Data\02 CAD\2.01 Base Files\Working\Michael 0\ACHD_SD_CALCS_Seepage Bed B1 10/28/2019, 9:54 AM Version 9.0, December 2016 1 Project Name Seepage Bed B1 2 Enter number of Seepage Beds (25 3 Design Storm 4 Weighted Runoff Coefficient C 5 Area A (Acres) 6 Approved discharge rate (if applicable) 7 Design Vol W/15% Sediment 8 Set'] otal Design Width of All Drain hock 1 300 0.74 Link to: OV QV TR55 0.81 aa -es C- 'a 0.00 cfs V 2,382 ft3 W 15.0 ft 9 Set Total Design Depth of All Drain Rock D 7.0 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 2.40 in/hr 12 Size of WQ Perf Pipe (Pert 180(') Dia pipe 18 in 13 Size of Overflow Perf Pipe (Perls 360°), REQD if Q100>3.3 cfs in 14 Calculate Total Storage per Fool Spf 42.2 ftl/ft Spf=Apf=WxD-Ar„ri_P;roxVoids+3./2 Perf–Area 15 Calculate Design Length Override Value Required for Chambers 16 Variable Infiltration Window L 17 Variable Infiltration Window W 18 Time to Drain 90% volume in 48 -hours minimum 19 Length of WQ & Overflow Perf Pipes 20 Perf Pipe Checks. Qperf - Qpeak; where Qperf=CdxAxV(2xgxH) L 56 57 ft SWL 57 ft SWW 15.0 ft 12.5 hours onlaffm 57 ft H:\!2018\ID-1336-1808 Eagle View Plaza\Project Data\02 CAD\2.01 Base Files\Working\Michael 0\ACHD_SD_CALCS_See"Ji�8101% 9:55 AM Version 9.0, December 2016 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. (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 Seepage Bed B2 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) 5 Area of Drainage Subbasin (SF or Acres) Acres Acres 6 Determine the Weighted Runoff Coefficient (C) C=((C1xA1)+(C2xA2)+(CnxAn))/A Weighted Avg Click to Show More Subbasins ❑ Subbasin Runoff Coefficients "1 Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 10 0.75 0.25-0.40 Apartment Dwelling Areas 0.70 Industrial and Commercial Light areas 0.75 Heavy areas 0.90 Parks, Cemeteries 0.10-0.25 Playgrounds 0.20-0.35 0.80 Railroad yard areas 0.20-0.40 Unimproved areas 0.10.0.30 Streets 0.80 0.95 Concrete 0.95 Brick 0.95 Roofs ............_..... 7 Calculate Overland Flow Time of Concentration in Minutes (Tc) or use default user calculate 10 min [10 Min. Estimated Runoff Coefficients for Various Surfac Type of Surface Runoff Coefficients "1 _ Business Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 Residential Single Family 0.35.0.50 Multi -family 0.60-0.75 Residential (rural) 0.25-0.40 Apartment Dwelling Areas 0.70 Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Parks, Cemeteries 0.10-0.25 Playgrounds 0.20-0.35 Railroad yard areas 0.20-0.40 Unimproved areas 0.10.0.30 Streets Asphalt 0.95 Concrete 0.95 Brick 0.95 Roofs 0.95 Gravel 0.75 Fields: Sandy soil Soil Type Slope AB C D Flat: 04;G 0.04 o.07 0.11 0. Average: 2.6% 0.09 0.12 0.15 0, Steep:>W, 0.13 0.18 0.23 0. Adapted from ASCE H:\12018\ID-1336.1808 Eagle View Plaza\Project Data\02 CAD\2.01 Base Files\Working\Michael 0\ACRD SD_CALCS_Seepage Bed B2 10/28/2019,9:56 AM Version 9.0, December 2016 I Project Name Seepage Bed B2 2 Enter number of Seepage Beds (25 max) 1 3 Design Storm 4 Weighted Runoff Coefficient C 5 Area A (Acres) 6 Approved discharge rate (if applicable) 7 Design Vol W/15%Sediment 8 Set Total Design Width of All Drain Rock 1.00 0.80 Link to: LOW QV TR55 1 0.75 acres t 0.00 ds V 2,385 ft3 W 20.0 ft 9 Set Total Design Depth of All Drain Rock D 7.0 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 2.40 in/hr 12 Size of WQ Perf Pipe (Perf 1.80") Dia pipe 18 in 13 Size of Over Perf Pipe (Perfs 360°), REQD if Q100>3.3 cfs in 14 Calculate Total Storage per Foot Spf=Apf=WxD-Apps p;r,exVoidsil/2 Perf—Area 15 Calculate Design Length Override Value Required for Chambers 1.6 Variable Infiltration Window L 17 Variable Infiltration Window W 18 Time to Drain 90% volume in 48 -hours minimum 19 Length of WQ & Overflow Perf Pipes 20 Perf Pipe Checks. Qperf >= Qpeak; where Qperf=CdxAxV(2xgxH) Spf 56.2 W/ft L 42 45 ft SWL 45 ft SWW 20.0 ft 11.9 hours MINWOM 45 ft TM H:\12018\ID-1336-1808 Eagle View Plaza\Project Data\02 CAD\2.01 Base Files\Working\Michael O\ACHD_SD_CALCS_See�®JZ'Sj'@dam 9:56 AM Version 9.0, December 2016 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. [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 Seepage Bed CS 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) 5 Area of Drainage Subbasin (SF or Acres) SF Acres 6 Determine the Weighted Runoff Coefficient (C) C=I(CixAl)+(C2xA2)+(CnxAn))/A Weighted Avg Click to Show More Subbasins ❑ Subbasin Type of Surface Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin 1 Subbasin 2 3 4 5 6 7 8 9 30 28,745 Light areas 0.80 Heavy areas 0.90 Parks, Cemeteries 0.10.0.25 Playgrounds 0.20.0.35 Railroad yard areas 0.66 Unimproved areas 0.10.0.30 Streets Asphalt 0.95 Concrete 0.95 Brick 0.90 Roofs 0.95 Gravel 0.75 Fields: Sandy soil Soil Type Slope A 8 C D Flat: O-2% 0.90 Average: 2-6% 0.09 0.12 0.15 0.. Steep:>6Y 0.13 0.18 0,23 0. Adapted from ASCE 7 Calculate Overland Flow Time of Concentration in Minutes (Tc) or use default User calculate 10 min [10 Min. Estimated Runoff Coefficients for Various Surface Type of Surface Runoff Coefficients "I Business Downtown areas 0.70-0.95 Urban neighborhoods 0.50-0.70 Residential Single Family 0.35-0.50 Multi -family 0.60.0.75 Residential (rural) 0.25.0.40 Apartment Dwelling Areas 0.70 Industrial and Commercial Light areas 0.80 Heavy areas 0.90 Parks, Cemeteries 0.10.0.25 Playgrounds 0.20.0.35 Railroad yard areas 0.20.0.40 Unimproved areas 0.10.0.30 Streets Asphalt 0.95 Concrete 0.95 Brick 0.95 Roofs 0.95 Gravel 0.75 Fields: Sandy soil Soil Type Slope A 8 C D Flat: O-2% 0.04 OW 0.11 0. Average: 2-6% 0.09 0.12 0.15 0.. Steep:>6Y 0.13 0.18 0,23 0. Adapted from ASCE H;\12018\ID-1336-1808 Eagle View Plaza\Project Data\02 CAD\2.01 Base Files\Working\Michael O\ACHD_SD_CALCS_Seepage Bed C1 10/28/2019,9:57 AM Version 9.0, December 2016 1 Project Name Seepage Bed C1 2 Enter number of Seepage Beds (25 3 Design Storm 4 Weighted Runoff Coefficient C 5 Area A (Acres) 6 Approved discharge rate (if applicable) 7 Design Vol W/1.5% Sediment V 100 0.90 0.66 acres 0.00 cfs 2,360 8 Set rota) Design Width of All Drain Rock W 20.0 ft 9 Set Total Design Depth of All Drain Rock D 7.0 ft Rock Only, Do Not Include Filter Sand Depth or Cover 10 Void Ratio of Drain Pock Voids 0.4 0.4 for 1.5"-2" drain rock and 3/4" Chips 11 Design Infiltration Rate (8 in/hr max) Pei c 2.40 in/hr 1.2 Size of WQ Perf Pipe (Perf 180°) Dia pipe 18 in 13 Size of Overflow Perf Pipe (Perfs 360°), REQD if Q100>3.3 cfs in 14 Calculate total Storage per Foot Spf Spf=Apf=WxD-Ap"rf p;pexVoids+l/2 Perf—Area 15 Calculate Design Length Override Value Required for Chambers 16 Variable Infiltration Window L 17 Variable Infiltration Window W 18 Time to Drain 90% volume in 48 -hours minimum 19 Length of WQ & Overflow Perf Pipes 20 Perf Pipe Checks. Qaeri >= Qpeak; where Qperf-CdxAxV(2xgxH) 1 Link to: Q.V QV TR55 1 ft3 56.2 ft3/ft 43 ft H:\!2018\ID-1336-1808 Eagle View Plaza\Project Data\02 CAD\2.01 Base Files\Working\Michael 0\ACHD_SD_CALCS_See"JHJ@8M 9:58 AM Version 9.0, December 2016