HomeMy WebLinkAboutCC - Storm Drainage Calcs STORM DRAINAGE
REPORT
Millwood Subdivision
REVISED
December 5, 2023
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PREPARED FOR:
Epic Development
PREPARED BY:
EDM Partners, LLC
Runoff Coefficients
Existing C Values7Roof
r
C C
Roof 0.90 8,166
Conc/Walk 0.90 k 0.90 5,555
Roadway 0.85 16,042 0.90 28,146
Landscape/Pasture 0.15 154,775 0.90 5,644
Total Area 178,983 New House/Driv 0.90 48,000
Weighted C Value: 0.25 Landscape 0.15 91,638
Total Area 178,983
Weighted C Value: 0.52
Runoff Flow& Pipe Sizing Pipe Check
Drainage Drainage Area Cumm 25 Yr Rainfall 100 yr Rainfall 100 yr flow Cumm. Cumm. dia. S A Rh Qauow 25 r 100 r
Drainage Basin Inlet 18asin Downstream Intel Area(SF) (acres) Drainage Area C Tc(min) (inlhr) (inlhr) 25 yr flow(cfs) ( ) 25 yr Flow(cfs) 100 yr flow Y Y
(acres) cfs (in) n (ft/ft) (sf) (ft) (cfs) flow flow
DA 1 SD14 IB1 97,618 2.24 2.24 0.55 15 1.56 2.18 1.92 2.69 1.92 2.69 15 0.012 0.0050 1.23 0.31 4.96 OK OK
DA2 SD7 SB1 46,291 1.06 1.06 0.55 15 1.56 2.18 0.91 1.27 0.91 1.27 15 0.012 0.0061 1.23 0.31 5.48 OK OK
DA3 SD8 SD12 5,942 0.14 0.14 0.55 15 1.56 2.18 0.12 0.16 0.12 0.16 15 0.012 0.0139 1.23 0.31 8.27 OK OK
DA3 SD10 SD12 19,930 0.46 0.46 0.55 15 1.56 2.18 0.39 0.55 0.39 0.55 15 0.012 0.0050 1.23 0.31 4.96 OK OK
DA3 SD12 SB2 - 1 0.00 0.59 1 0.55 15 1.56 1 2.18 0.00 0.00 1 0.51 0.71 1 18 10.012 0.0020 11.7710.38 5.10 1 OK I OK
Total 169,781 3.90 3.90 0.55 15 1.56 2.18 3.34 4.67 3.34 4.67
Total(By BMP) 161 0.00 2.24 0.55 15 1.56 2.18 0.00 0.00 1.92 2.69
SB1 0.00 1.06 0.55 15 1.56 2.18 0.00 0.00 0.91 1.27
S132 0.00 0.59 0.55 15 1.56 2.18 0.00 0.00 0.51 0.71
DischargeJIL MD & Runoff Volumes
Sediment Runoff+
100-yr1-hr Event Time of Runoff Runoff
Storage Sediment
Size Event Concentratio
Area (ac) in Duration Coefficient Volume Allowance Volume BMP
In
DA 1 2.24 0.96 1 hr 10 Min. 0.55 4,260 CF 0% 4,260 CF 1131
DA 2 1.06 0.96 1 hr 10 Min. 0.55 2,020 CF 25% 2,525 CF SB1
DA 3 1 0.59 1 0.96 1 1 hr 10 Min. 0.55 1,129 CF 25% 1,411 CF SB2
Millwood Subdivision 3.90 0.96 1 hr 10 Min. 0.55 7,409 CF 25% 9,261 CF
Seepage Drainage Drain Rock Infiltration Rate Required Req'd Vol Storage Time to
Bed Basin Depth Width Length (in/hr) Volume w125%Seds Volume* Drain
SB1 DA2 5.00 FT 14.50 FT 84.0 FT 1 2,020 CF 2,525 CF 2,436 CF 19.9 hrs
SB2 DA3 6.00 FT 10.00 FT 56.0 FT 1 1,129 CF 1,411 CF 1,344 CF 24.2 hrs
Storage Volume shown is calculated without factoring infiltration
Infiltration Basin Storage
BMP: 1131 DA:DA 1 Required Storage: 4,260 CF
Design Vol Surface Area @ Storage
Contour Area Storage Design Volume Elev Design Pool Volume Freeboard
(ft) (sf) (Cu ft) (cu ft) (ft) (sf) (ft) (ft)
2656.00 2203 4463 3378 2655.27 1855.38 2.27 0.73
2653.00 772
Available Surface Storage(cu ft)= 4463
Utilized Surface Storage(cu ft)= 4463
10.25
Subsurface Storage
ock Choker Depth: 0.33
Rock Depth: 1.00 System Bottom: 2,651.67
Bed Footprint: 2203 EG: 2,654
Raw Vol: 2203 SHGVVE: 2,648
Storage Vol: 881.2 Separation: 3.4
Total BMP Storage(cu ft)= 5344
Adequate Storage
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 Millwood Subdivision
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) 3
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 97,618
Acres 2.24
6 Determine the Weighted Runoff Coefficient(C) 0.55
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 1 0.55
7 User Calculate J
Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 min Estimated Runoff Coefficients for Various Surfact
J Type of Surface Runoff Coefficients"(
Business
8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr Downtown areas 0.70-0.95
9 Calculate the Post-Development peak discharge(QPeak) QPeak 3.18 cfs Urban neighborhoods 0.50-0.70
Residential
Single Family 0.35-0.50
10 Calculate total runoff vol(V)(for sizing primary storage) V 4,260 W Multi-family 0.60-0.75
V=Ci(Tc=60)Ax3600 Residential(rural) 0.25-0.40
11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70
Industrial and Commercial
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in Light areas 0.80
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) V„ 2,662 W Heavy areas 0.90
Parks,Cemeteries 0.10-0.25
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Playgrounds 0.20-0.35
Railroad yard areas 0.20-0.40
13 Volume Summary Unimproved areas 0.10-0.30
Surface Storage:Basin streets
Asphalt 0.95
Basin Forebay V 426 W concrete 0.95
Primary Treatment/StorageBasin V 3,834 W Brick 0.95
Subsurface Storage Roofs 0.95
Gravel 0.75
Volume Without Sediment Factor(See BMP 20 Tab) V 4,260 W 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 D.:
Steep:>6% 0.13 0.18 0.23 a.:
Adapted from ASCE
ACHD_SD_CALCS_112018 1.xlsm 12/5/2023,5:19 PM
Version 10.5,November 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.
Sculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name Millwood Subdivision,Facility 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
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 46,291
Acres 1.06
6 Determine the Weighted Runoff Coefficient(C) 0.55
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 1 0.55
7 User Calculate J
Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 min Estimated Runoff Coefficients for Various Surfacc
Type of Surface Runoff Coefficients"(
8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr Business
Downtown areas 0.70-0.95
9 Calculate the Post-Development peak discharge(QPeak) Qpeak 1.51 cfs Urban neighborhoods 0.50-0.70
Residential
10 Calculate total runoff vol V for sizing Single Family 0.35-0.50
( )( g primary storage) V 2,020 ft3 Multi-family 0.60-0.75
V=Ci(Tc=60)Ax3600 Residential(rural) 0.25-0.40
11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70
Industrial and Commercial
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in fight areas 0.80
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 1,262 ft3 Heavy areas 0.90
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,Cemeteries 0.10-0.25Playgrounds 0.20-0.35
Railroad yard areas 0.20-0.40
13 Volume Summary Unimproved areas 0.10-0.30
Surface Storage:Basin Streets
Asphalt 0.95
Basin Forebay V 202 ft3 Concrete 0.95
Primary Treatment/StorageBasin V 1,818 ft3 Brick 0.95
Subsurface Storage Roofs 0.95
Gravel 0.75
Volume Without Sediment Factor(See BMP 20 Tab) V 2,020 ft3 Fields:Sandy soil Soil Type
Slope A B C D
Flat:0-2% 0.04 0.07 0.11 13
Average:2-6% 0.09 0.12 0.15 O.:
Steep:>6% 0.13 0.18 0.23 D.:
Adapted from ASCE
ACHD_SD_CALCS_112018 1.xlsm 12/5/2023,5:19 PM
Version 10.5,November 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.
Sculate Post-Development Flows(for pre-development flows,increase number of storage facilities to create new tab)
User input in yellow cells.
1 Project Name Millwood Subdivision,Facility 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
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 25,872
Acres 0.59
6 Determine the Weighted Runoff Coefficient(C) 0.55
C=[(C1xA1)+(C2xA2)+(CnxAn)]/A Weighted Avg 1 0.55
7 User Calculate J
Calculate Overland Flow Time of Concentration in Minutes(Tc)or use default 10 min Estimated Runoff Coefficients for Various Surfacc
Type of Surface Runoff Coefficients"(
8 Determine the average rainfall intensity(i)from IDF Curve based on Tc i 2.58 in/hr Business
Downtown areas 0.70-0.95
9 Calculate the Post-Development peak discharge(QPeak) Qpeak 0.84 cfs Urban neighborhoods 0.50-0.70
Residential
Single Family 0.35-0.50
10 Calculate total runoff vol(V)(for sizing primary storage) V 1,129 ft3 Multi-family 0.60-0.75
V=Ci(Tc=60)Ax3600 Residential(rural) 0.25-0.40
11 Calculate Volume of Runoff Reduction Vrr Apartment Dwelling Areas 0.70
Industrial and Commercial
Enter Percentile Storm I(95th percentile=0.60 in) 95th 0.60 in fight areas 0.80
Enter Runoff Reduction Vol(95th Percentile=0.60-in x Area x C) Vrr 706 ft3 Heavy areas 0.90
12 Detention:Approved Discharge Rate to Surface Waters(if applicable) cfs Parks,Cemeteries 0.10-0.25Playgrounds 0.20-0.35
Railroad yard areas 0.20-0.40
13 Volume Summary Unimproved areas 0.10-0.30
Surface Storage:Basin Streets
Asphalt 0.95
Basin Forebay V 113 ft3 Concrete 0.95
Primary Treatment/StorageBasin V 1,016 ft3 Brick 0.95
Subsurface Storage Roofs 0.95
Gravel 0.75
Volume Without Sediment Factor(See BMP 20 Tab) V 1,129 ft3 Fields:Sandy soil Soil Type
Slope A B C D
Flat:0-2% 0.04 0.07 0.11 13
Average:2-6% 0.09 0.12 0.15 0.:
Steep:>6% 0.13 0.18 0.23 D.:
Adapted from ASCE
ACHD_SD_CALCS_112018 1.xlsm 12/5/2023,5:19 PM
Version 10.5,November 2018
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's
calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet
or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak QV"tab
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 Millwood Subdivision,Facility 2
2 Enter number of Seepage Beds(25 max) 1
3 Design Storm 100
I 4 Weighted Runoff Coefficient C 0.55 Link to: Q,V J
I5 Area A(Acres) 1.06 acres Q,V3
I 6 Approved discharge rate(if applicable) 0.00 cfs Q.V TR55
7 Is Seepage Bed in Common Lot? No V 2,525 ft3 25%Sediment
I8 Set Total Design Width of All Drain Rock W 14.5 ft
I 9 Set Total Design Depth of All Drain Rock D 5.0 ft
IRock Only,Do Not Include Filter Sand Depth or Cover
I 10 Void Ratio of Drain Rock Voids 0.4
I0.4 for 1.5"-2"drain rock and 3/4"Chips
I 11 Design Infiltration Rate(8 in/hr max) Perc 1.00 in/hr
12 Size of WQ Perf Pipe(Pert 180°) Dia pipe 18 in
I 13 Size of Overflow Perf Pipe(Perfs 3600),READ if Q100>3.3 cfs in
I 14 Calculate Total Storage per Foot Spf 30.4 ft3/ft
I15 Calculate Design Length L 0 84 ft
IOverride Value Required for Chambers
I 16 Variable Infiltration Window L SWL 84 ft
I 17 Variable Infiltration Window W SWW 14.5 ft
18 Time to Drain 22.4 hours
90%volume in 48-hours minimum
I 19 Length of WQ&Overflow Perf Pipes 84 ft
20 Perf Pipe Checks.Qperf>=Qpeak;
I where Qperf=CdxAxV(2xgxH)
Optional Storage Chambers
Note:This assumes chambers are organized in a rectangular layout.
1-StormTech,
1 Type of Chambers SC740
2 Volume to Store V 0 ft3
3 Installed Chamber Width Cw 4.25 ft
Installed Chamber Depth Cd 2.50 ft
Installed Chamber Height Ch 7.12 ft
4 Chamber Void Factor
5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit
6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit
7 Total Number of Units Required 0 ea
8 Area of Infiltration Aperc ft2
9 Volume Infiltration Vperc 0 ft3/hr
10 Time to Drain hours
90%volume in 48-hours minimum
ACHD_SD_CALCS_112018 1.xlsm 12/5/2023,5:19 PM
Version 10.0,May 2018
ACHD Calculation Sheet for Sizing Seepage Bed With Optional Chambers
NOTE:This worksheet is intended to be a guideline to standardize ACHD checking of drainage calculations and shall not replace the Engineer's
calculation methodology. These calculations shall establish a minimum requirement.The Engineer's methodology must result in facilities that meet
or exceed these calculations in order to be accepted.
Note this spreadsheet pulls information from the"Peak QV"tab
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 Millwood Subdivision,Facility 3
2 Enter number of Seepage Beds(25 max) 1
3 Design Storm 100
I 4 Weighted Runoff Coefficient C 0.55 Link to: Q•V J
I 5 Area A(Acres) 0.59 acres QY2
I 6 Approved discharge rate(if applicable) 0.00 cfs Q,V TR55
7 Is Seepage Bed in Common Lot? No V 1,411 ft3 25%Sediment
I8 Set Total Design Width of All Drain Rock W 10.0 ft
I 9 Set Total Design Depth of All Drain Rock D 6.0 ft
IRock Only,Do Not Include Filter Sand Depth or Cover
I 10 Void Ratio of Drain Rock Voids 0.4
I0.4 for 1.5"-2"drain rock and 3/4"Chips
I 11 Design Infiltration Rate(8 in/hr max) Perc 1.00 in/hr
12 Size of WQ Perf Pipe(Pert 1800) Dia pipe 18 in
I 13 Size of Overflow Perf Pipe(Perfs 3600),READ if Q100>3.3 cfs in
I 14 Calculate Total Storage per Foot Spf 25.0 ft3/ft
I15 Calculate Design Length L 0 56 ft
IOverride Value Required for Chambers
I 16 Variable Infiltration Window L SWL 56 ft
I 17 Variable Infiltration Window W SWW 10.0 ft
18 Time to Drain 27.2 hours
90%volume in 48-hours minimum
I 19 Length of WQ&Overflow Perf Pipes 56 ft
20 Perf Pipe Checks.Qperf>=Qpeak;
I where Qperf=CdxAxV(2xgxH)
Optional Storage Chambers
Note:This assumes chambers are organized in a rectangular layout.
1-StormTech,
1 Type of Chambers SC740
2 Volume to Store V 0 ft3
3 Installed Chamber Width Cw 4.25 ft
Installed Chamber Depth Cd 2.50 ft
Installed Chamber Height Ch 7.12 ft
4 Chamber Void Factor
5 Chamber Storage Volume,Without Rock,Per Manuf 45.90 ft3/Unit
6 Chamber Storage Volume,With Rock,Per Manuf 74.90 ft3/Unit
7 Total Number of Units Required 0 ea
8 Area of Infiltration Aperc ft2
9 Volume Infiltration Vperc 0 ft3/hr
10 Time to Drain hours
90%volume in 48-hours minimum
ACHD_SD_CALCS_112018 1.xlsm 12/5/2023,5:19 PM
Version 10.0,May 2018