SW3171201_Design Calculations (E&SC)_20180827

STORM DRAINAGE AND
EROSION CONTROL CALCULATIONS
VILLAGE AT GRANITE QUARRY
- PHASE 1
Granite Quarry, Rowan County, North Carolina
Prepared for:
LGI HOMES
Contact: Jeff Webb
3037 Sherman Drive
Lancaster, SC
P. 844-566-4300
Prepared by:
DPR Associates, Inc.
420 Hawthorne Lane
Charlotte, NC 28204
P. 704-332-1204
F. 704-332-1210
www.dprassociates.net
DPR Project No.: 17031
November 27, 2017
February 26, 2018
March 30, 2018
April 18, 2018
June 25, 2018
6-25-2018
_______________________ _____________________
DPR Associates, Inc. Hy V. Nguyen, PE
Project: Village at Granite QuarryJob #: 17031Location: Salsbury, Rowan Co, NCStorm Frequency: 25yr.DPR ASSOCIATESGrate Drop Inlet Calculations Computed by: RJChecked by: MBDate: 11-13-17Weir FlowOrifice Flow:Structure #: Drainage Area (ac) Runoff CoefficientRainfall Intensity (in/hr)Q25 (cfs) UNLESS NOTEDWeir Coefficient (Cw):Length of Weir (ft)Height of Water Buildup (ft):Coefficient of Discharge Grate Slot Length (in):Grate Slot Width (in)Grate Slot NumberArea of Flow (sf):Height of Water Buildup (ft):Maximum Height of Water YEAR STORM1-1040.70 0.5 7.82 3.01 3 100.220.6 16.5 2 16 3.670.03 0.22 (ft)25 yr. 5 min.1-1060.30 0.5 7.82 1.29 3 100.120.6 16.5 2 16 3.670.01 0.12 (ft)25 yr. 5 min.1-2000.60 0.5 7.82 2.58 3 100.190.6 16.5 2 16 3.670.02 0.19 (ft)25 yr. 5 min.1-3000.30 0.5 7.82 1.29 3 100.120.6 16.5 2 16 3.670.01 0.12 (ft)25 yr. 5 min.2-1030.60 0.5 7.82 2.58 3 100.190.6 16.5 2 16 3.670.02 0.19 (ft)25 yr. 5 min.2-1120.50 0.5 7.82 2.15 3 100.170.6 16.5 2 16 3.670.01 0.17 (ft)25 yr. 5 min.2-1130.10 0.5 7.82 0.43 3 100.060.6 16.5 2 16 3.670.00 0.06 (ft)25 yr. 5 min.2-1170.70 0.5 7.82 3.01 3 100.220.6 16.5 2 16 3.670.03 0.22 (ft)25 yr. 5 min.2-1180.60 0.5 7.82 2.58 3 100.190.6 16.5 2 16 3.670.02 0.19 (ft)25 yr. 5 min.2-1190.30 0.5 7.82 1.29 3 100.120.6 16.5 2 16 3.670.01 0.12 (ft)25 yr. 5 min.3-2070.40 0.5 7.82 1.72 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.3-214B0.90 0.5 7.82 3.87 3 100.260.6 16.5 2 16 3.670.05 0.26 (ft)25 yr. 5 min.5-1020.50 0.5 7.82 2.15 3 100.170.6 16.5 2 16 3.670.01 0.17 (ft)25 yr. 5 min.T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\STORM & EC\PHASE 1\17031-DropInlet-grate progress.xlsPlotted 3/30/2018Sheet: 1 of 2
Project: Village at Granite Quarry
DPR Job No.: 17031
Location: Rowan Co, NC
DPR ASSOCIATES
Design of Slab Inlets
Prepared by: RJ
Checked by: MB
Date:11-14-17
Structure #:3-211 (slap type) NCDOT 840.04
Drainage Area (ac): 3.8 24" RCP
Runoff Coefficient (c): 0.5
Rainfall Intensity (in/hr): 7.82
Q25 (cfs): 16.3
Weir Flow:
Weir Coefficient (Cw): 3.0 (Cw=3.0 for free overfall)
Length of Weir (ft): 13.3 (Length of Drop Inlet opening)
Height of Water Buildup (ft): 0.55
Orifice Flow:
Coefficient of Discharge (Cd): 0.6 (Cd=0.6 typical)
Orifice opening height (in): 6.0
Area of Flow (sf): 6.65
Acceleration of Gravity: 32.2
Height of Water Buildup (ft): 0.26
Maximum Height of Water Buildup = 0.55 (ft)
Structure #:4-100A (slap type) NCDOT 840.04
Drainage Area (ac): 0.6 15" RCP
Runoff Coefficient (c): 0.5
Rainfall Intensity (in/hr): 7.82
Q25 (cfs): 2.6
Weir Flow:
Weir Coefficient (Cw): 3.0 (Cw=3.0 for free overfall)
Length of Weir (ft): 11.5 (Length of Drop Inlet opening)
Height of Water Buildup (ft): 0.18
Orifice Flow:
Coefficient of Discharge (Cd): 0.6 (Cd=0.6 typical)
Orifice opening height (in): 6.0
Area of Flow (sf): 5.75
Acceleration of Gravity: 32.2
Height of Water Buildup (ft): 0.01
Maximum Height of Water Buildup = 0.18 (ft)
Structure #:5-106 (slap type) NCDOT 840.04
Drainage Area (ac): 1.4 15" RCP
Runoff Coefficient (c): 0.5
Rainfall Intensity (in/hr): 7.82
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\STORM & EC\PHASE 1\17031-Slab Inlet.xlsPlotted 3/30/2018 Sheet: 1 of 2
Project: Village at Granite Quarry
DPR Job No.: 17031
Location: Rowan Co, NC
DPR ASSOCIATES
Design of Slab Inlets
Prepared by: RJ
Checked by: MB
Date:11-14-17
Q25 (cfs): 6.0
Weir Flow:
Weir Coefficient (Cw): 3.0 (Cw=3.0 for free overfall)
Length of Weir (ft): 11.5 (Length of Drop Inlet opening)
Height of Water Buildup (ft): 0.31
Orifice Flow:
Coefficient of Discharge (Cd): 0.6 (Cd=0.6 typical)
Orifice opening height (in): 6.0
Area of Flow (sf): 5.75
Acceleration of Gravity: 32.2
Height of Water Buildup (ft): 0.05
Maximum Height of Water Buildup = 0.31 (ft)
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\STORM & EC\PHASE 1\17031-Slab Inlet.xlsPlotted 3/30/2018 Sheet: 2 of 2
STORMWATER ANALYSIS FOR FAITH ROAD
Project: Village at Granite
DPR Job No.: 17031
Location: Granite Quarry, NC
DPR ASSOCIATES
TIME OF CONCENTRATION
Prepared by: RJ
Checked by: HN
Date: 4-18-18
EXISTING CONDITION - TIME OF CONCENTRATION (BMP #6)
SHEET FLOW:
Surface Description = grass
Manning's Roughness (n) = 0.24
Flow Length (ft) = 100
Slope (%) = 5.5
P-2yr (in.) = 3.12
T(t) (min.) =9.6
CHANNEL FLOW:
Average Channel Area (sf) =4.00 Bottom Width (ft) = 2
Hydraulic Radius =0.618 Side Slope (X:1) = 2
Flow Length (ft) = 315
Channel Slope (%) = 2 Depth (ft) = 1
Manning's Coefficient (n) = 0.048
Velocity (fps) =3.19
T(t) (min.) =1.6
CHANNEL FLOW:
Average Channel Area (sf) =4.00 Bottom Width (ft) = 2
Hydraulic Radius =0.618 Side Slope (X:1) = 2
Flow Length (ft) = 148
Channel Slope (%) = 2 Depth (ft) = 1
Manning's Coefficient (n) = 0.048
Velocity (fps) =3.19
T(t) (min.) =0.8
T(t) Sum of Travel Time (min)= 12.1 Time =12 (min.)
Hydraulic Length = 563 ft
Basin Slope = 2.4
POST DEVELOPMENT - TIME OF CONCENTRATION
Time =5 (min.)
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-TOC.xlsPlotted 8/13/2018 Sheet: 1 of 1
Project: Village at GraniteDPR Job No.: 17031Location: Granite Quarry, NCDPR ASSOCIATES, INCRUN-OFF CURVE NUMBERPrepared by: RJChecked by: MBDate: 11-17-176Total Drain. Area (Ac.)5.50Site Soil TypeSoil GroupPercentage of BasinCeB2B4.3 ac78.2%ChAB/D0.0 ac0.0%VnB2, VnC2C1.2 ac21.8%5.5 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.0%5543.0660.07015.3 58.3 0.0Open Space - Grass and Shurbs (Good Cond.)5.0090.9%6147.7710.07416.1 63.8 58.0Impervious0.509.1%9876.6980.09821.4 98.0 8.966.9Total5.5100%Composite Curve Number (CN):66.96Total Drain. Area (Ac.)6.00Site Soil TypeSoil GroupPercentage of BasinCeB2B4.8 ac80.0%ChAB/D0.0 ac0.0%VnB2, VnC2C1.2 ac20.0%6.0 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.000.0%5544.0660.07014.0 58.0 0.0Open Space - Grass and Shurbs (Good Cond.)4.4073.3%6148.8710.07414.8 63.6 46.6Impervious1.6026.7%9878.4980.09819.6 98.0 26.172.8Total6.0100%Composite Curve Number (CN):73Existing Condition Watershed BMP #Proposed Development Watershed BMP #T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Runoff CN.xlsSheet: 1 of 1 8/13/2018
Project: Village at GraniteDPR Job No.: 17031Location: Granite Quarry, NCDPR ASSOCIATES, INCRUN-OFF CURVE NUMBERPrepared by: RJChecked by: MBDate: 11-17-17Total Drain. Area (Ac.)4.30Site Soil TypeSoil GroupPercentage of BasinCeB2B3.0 ac69.8%ChAB/D0.0 ac0.0%VnB2, VnC2C1.3 ac30.2%4.3 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)3.0069.8%5538.4660.07021.2 59.5 41.5Open Space - Grass and Shurbs (Good Cond.)1.2027.9%6142.6710.07422.4 64.9 18.1Impervious0.102.3%9868.4980.09829.6 98.0 2.361.9Total4.3100%Composite Curve Number (CN):61.9Total Drain. Area (Ac.)5.00Site Soil TypeSoil GroupPercentage of BasinCeB2B1.0 ac20.0%ChAB/D2.6 ac52.0%VnB2, VnC2C1.4 ac28.0%5.0 ac100.0%Hydrologic Soil Group UsedLand UseNo. AcresPercent of Drainage AreaCN for Group BGroup B Weighted CN CN for Group B/DGroup B/D Weighted CN CN for Group CGroup C Weighted CN Total Weighted CN Weighted CN %Wood (Good Cond.)0.000.0%5511.06634.37019.6 64.9 0.0Open Space - Grass and Shurbs (Good Cond.)4.7094.0%6112.27136.97420.7 69.8 65.6Impervious0.306.0%9819.69851.09827.4 98.0 5.971.5Total5.0100%Composite Curve Number (CN):72Existing Condition Undetain AreaProposed Development Undetain AreaT:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-Runoff CN.xlsSheet: 1 of 1 8/13/2018
Project: Village at Granite
Job No.: 17031
Location: Granite Quarry, NC
Sheet: 1 of 2
DPR ASSOCIATES, INC
SAND FILTER-1 DESIGN
Prepared By: RJ
Checked By: HN
Date: 10-17-17
Revised: 12-21-17
DESIGN CRITERIA PER NCDENR STORMWATER DESIGN MANUAL DATED JAN 2017
* BMP - DRY POND 6
* Total Drainage Area:6.00 ac
* Total Storm Water Volume Control 1-yr, 24-hr Post-Dev:
Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) =12,315 cf
(SCS Method)
P: Design Storm, 1-yr 24-hr Storm Rainfall depth 2.80 inch
A: Drainage Area 6.00 ac.
S = 1,000/CN-10 =4.49 inch
CN: Curve Number 69
* Estimated Storm Water Volume 10-yr, 24-hr Post-Dev:
Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) =20,257 cf
(SCS Method)
P: Design Storm, 10-yr 24-hr Storm Rainfall depth 3.46 inch
A: Drainage Area 6.00 ac.
S = 1000/CN-10 =4.49 inch
CN: Curve Number 69
BMP Storage Volume Provided:
Elevation Surface Area Storage Total Storage
(ft) (sf) (cf) (cf)
753.0 50 00Bottom of Pond
754.0 5,000 2,525 2,525
756.0 7,000 12,000 14,525
758.0 23,100 30,100 44,625
760.0 58,300 81,400 126,025 Top of Embankment
Static Channel Protection Elevation @ 755.64 ft
* Orifice Calcs For Channel Protection Dewatering Time 2 days (48 hrs) Beyond Center of 24-hr Storm
(Sized for the Volume of 1-yr Storm with 50% remained at 36th Hour, 5% remained at 60th Hour,
and drained completely at 120th Hour).
1-yr Storm Volume, Less 50% Remain Beyond 36th Hour 6,158 cf
Average Surface Area 2,332 sf
Area of Outlet Orifice (sf), a = (2)(A)h^(1/2))/(c)(t)(2g)^(1/2)) (NCDENR, Orifice Equation)
a = 0.012 where:
A= Resevoir Area, sf 2,332
Max. Orifice Diameter (inch), d = 1.49 h= Falling Head, ft 2.58
c= Discharge Coefficient 0.6
Orifice Diameter (inch) Used, d =1.5 t= Time ( 36 hrs), sec.129,600
g= Accelleration, ft/sq.sec 32.2
a= Orifice Area (sf)
d= Orifice Diameter (inch)
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\CALCS\BMP\Phase 1\17031-PH1-BMP Dry Detention.xls
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Project: Village at Granite
Job No.: 17031
Location: Granite Quarry, NC
Sheet: 2 of 2
DPR ASSOCIATES, INC
SAND FILTER-1 DESIGN
Prepared By: RJ
Checked By: HN
Date: 10-17-17
Revised: 12-21-17
* BMP - SAND FILTER 6
Anti-Seep Collar Sizing
Outlet Pipe Size (I.D.) = 15 in
Outlet Pipe Size (O.D.) = 1.63 ft
L, Length of Outlet Pipe = 53 lf
Min. Flow Length = 61.0 ft Min. Flow Length = 115% of outlet pipe
Total Lengh of Collar offset = 8.0 ft
Number of anti-seep collars 2
Offset per collar 4.0 ft
Min. Outside dimension of each collar 5.60 ft
Designed collars 2 at 5.5' x 5.5'
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