SW3200401_17031-PH2 SD EC Calcs 3-11-2020_20200612

STORM DRAINAGE AND
EROSION CONTROL CALCULATIONS

VILLAGE AT GRANITE QUARRY
- PHASE 2

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

August 22, 2019
March 11, 2020

3-11-2020
______________________ _____________________
DPR Associates, Inc. Hy V. Nguyen, PE
DPR ASSOCIATESGrate Drop Inlet CalculationsWeir 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 STORM7-101 0.50 0.5 7.67 2.11 3 100.170.6 16.5 2 16 3.670.01 0.17 (ft)25 yr. 5 min.7-102 0.50 0.5 7.67 2.11 3 100.170.6 16.5 2 16 3.670.01 0.17 (ft)25 yr. 5 min.7-103 0.50 0.5 7.67 2.11 3 100.170.6 16.5 2 16 3.670.01 0.17 (ft)25 yr. 5 min.7-104 0.30 0.5 7.67 1.27 3 100.120.6 16.5 2 16 3.670.01 0.12 (ft)25 yr. 5 min.7-105 0.40 0.5 7.67 1.69 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.7-106 0.40 0.5 7.67 1.69 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.7-107 0.40 0.5 7.67 1.69 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.7-216 0.50 0.5 7.67 2.11 3 100.170.6 16.5 2 16 3.670.01 0.17 (ft)25 yr. 5 min.7-217 0.60 0.5 7.67 2.53 3 100.190.6 16.5 2 16 3.670.02 0.19 (ft)25 yr. 5 min.7-218 0.40 0.5 7.67 1.69 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.7-219 0.50 0.5 7.67 2.11 3 100.170.6 16.5 2 16 3.670.01 0.17 (ft)25 yr. 5 min.7-207 0.30 0.5 7.67 1.27 3 100.120.6 16.5 2 16 3.670.01 0.12 (ft)25 yr. 5 min.7-309 0.20 0.5 7.67 0.84 3 100.090.6 16.5 2 16 3.670.00 0.09 (ft)25 yr. 5 min.7-310 0.70 0.5 7.67 2.95 3 100.210.6 16.5 2 16 3.670.03 0.21 (ft)25 yr. 5 min.7-314 0.40 0.5 7.67 1.69 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.7-315 0.60 0.5 7.67 2.53 3 100.190.6 16.5 2 16 3.670.02 0.19 (ft)25 yr. 5 min.7-316 0.50 0.5 7.67 2.11 3 100.170.6 16.5 2 16 3.670.01 0.17 (ft)25 yr. 5 min.7-317 0.40 0.5 7.67 1.69 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.7-329 0.60 0.5 7.67 2.53 3 100.190.6 16.5 2 16 3.670.02 0.19 (ft)25 yr. 5 min.7-333 0.50 0.5 7.67 2.11 3 100.170.6 16.5 2 16 3.670.01 0.17 (ft)25 yr. 5 min.7-336A 0.60 0.5 7.67 2.53 3 100.190.6 16.5 2 16 3.670.02 0.19 (ft)25 yr. 5 min.7-336B 0.40 0.5 7.67 1.69 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.7-337 0.40 0.5 7.67 1.69 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.7-338 0.40 0.5 7.67 1.69 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.7-339 0.40 0.5 7.67 1.69 3 100.150.6 16.5 2 16 3.670.01 0.15 (ft)25 yr. 5 min.7-340A 0.30 0.5 7.67 1.27 3 100.120.6 16.5 2 16 3.670.01 0.12 (ft)25 yr. 5 min.T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2 SD Inlet Drop GratePlotted 3/11/2020Sheet: 1 of 2
DPR ASSOCIATESGrate Drop Inlet CalculationsWeir 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 STORM7-340C 0.60 0.5 7.67 2.53 3 100.190.6 16.5 2 16 3.670.02 0.19 (ft)25 yr. 5 min.8-201 0.30 0.5 7.67 1.27 3 100.120.6 16.5 2 16 3.670.01 0.12 (ft)25 yr. 5 min.8-202 0.10 0.5 7.67 0.42 3 100.060.6 16.5 2 16 3.670.00 0.06 (ft)25 yr. 5 min.8-203 0.30 0.5 7.67 1.27 3 100.120.6 16.5 2 16 3.670.01 0.12 (ft)25 yr. 5 min.8-204 0.20 0.5 7.67 0.84 3 100.090.6 16.5 2 16 3.670.00 0.09 (ft)25 yr. 5 min.8-205 0.20 0.5 7.67 0.84 3 100.090.6 16.5 2 16 3.670.00 0.09 (ft)25 yr. 5 min.8-206 0.30 0.5 7.67 1.27 3 100.120.6 16.5 2 16 3.670.01 0.12 (ft)25 yr. 5 min.8-211 0.20 0.5 7.67 0.84 3 100.090.6 16.5 2 16 3.670.00 0.09 (ft)25 yr. 5 min.8-212 0.30 0.5 7.67 1.27 3 100.120.6 16.5 2 16 3.670.01 0.12 (ft)25 yr. 5 min.T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2 SD Inlet Drop GratePlotted 3/11/2020Sheet: 2 of 2
DPR ASSOCIATES
Design of Slab Inlets
Structure #:7-318 (slap type) NCDOT 840.04
Drainage Area (ac): 1.50 18" RCP
Runoff Coefficient (c): 0.5
Rainfall Intensity (in/hr): 7.67
Q25 (cfs): 6.3
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): 0.32
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 = 0.32 (ft)
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2 SD Inlet SlabPlotted 3/11/2020 Sheet: 1 of 1
Project: Granite Quarry
DPR Job No.: 17031
Location: Granite Quarry, NC
DPR ASSOCIATES
Riser Basin Design Worksheet
(per NCDEHNR Design Manual)
Prepared by:MPB
Checked by: HVN
Date: 10-19-17
Riser Sediment Basin w/ Skimmer #7 (NCDENR- Erosion Control # 6.64)
Pre-Development
Drainage Area "A" (ac) = 5.5
Runoff Coefficient, Pre Dev (C) = 0.30 (After demoliation, Seeded condition)
Rainfall Intensity "I" (in/hr) = 7.24 (for 5 min time of concentration)
Flow "Q10" (cfs) =11.9 (Q10=C*I*A)
Post-Development
Drainage Area "A" (ac) = 26.0
Runoff Coefficient, Post Dev (C) = 0.60
Rainfall Intensity "I" (in/hr) = 7.24 (for 5 min time of concentration)
Flow "Q10" (cfs) =112.9 (Q10=C*I*A)
Designed Flow "Q10" =112.9 cfs
Elevation
Storage Required (cf) =46,800 (V = 1,800 sf per acre of drainage areas )
Storage Provided =50,000 720.0 (measured @ storage depth)
Surface Area Required (sf) =36,707 (325 sf per cfs)
Surface Area Provided =34,900 729.2 (measure @ spillway)
Storage Dimensions:
Basin Side Slopes ( x : 1 ) =2.0
Storage Depth "H" (ft) =6.0
Bottom Dimension =714.0 (See Erosion Control plan,
Sediment Storage Dimension at "H" =for actual basin areas and storage provided)
Top of Embankment Dimension =729.2
Use the larger of the two conditions
Use Permanent BMP Outlet Structure and Spillway.
See BMP Plans & Calcs
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2-EC Basins.xlsPlotted 8/16/2018 Sheet: 1 of 2
Project: Granite Quarry
DPR Job No.: 17031
Location: Granite Quarry, NC
DPR ASSOCIATES
Riser Basin Design Worksheet
(per NCDEHNR Design Manual)
Prepared by:MPB
Checked by: HVN
Date: 10-19-17
Riser Sediment Basin w/ Skimmer #7 (NCDENR- Erosion Control # 6.64)
Skimmer Max. Capacity Size w/out Orifice (cf)24 hrs 2 days 5 days 7 days
1 1/2" skimmer 1,728 3,456 8,640 12,096
2" skimmer 3,283 6,566 16,415 22,981
2 1/2" skimmer 6,234 12,468 31,170 43,638
3" skimmer 9,774 19,548 48,870 68,418
4" skimmer 20,109 40,218 100,545 140,763
5" skimmer 32,832 65,664 164,160 229,824
6" skimmer 51,840 103,680 259,200 362,880
Factors (CF of flow per square inch of opening through a round orifice for the draw down times shown)
24 hrs 2 days 5 days 7 days
1 1/2" skimmer 960 1,920 4,800 6,720
2" skimmer 1,123 2,246 5,615 7,861
2 1/2" skimmer 1,270 2,540 6,350 8,890
3" skimmer 1,382 2,764 6,910 9,674
4" skimmer 1,601 3,202 8,005 11,207
5" skimmer 1,642 3,284 8,210 11,494
6" skimmer 1,814 3,628 9,070 12,698
Draw down time:24 hr 2 days 5 days 7 days
Volume Area (in^2)Area (in^2)Area (in^2)Area (in^2)
A = pi x d^2 / 4 , d = sq.rt.(A*4/pi)10-yr (cf)Orifice Dia. (in)Orifice Dia. (in)Orifice Dia. (in)Orifice Dia. (in)
Try 1 1/2" Skimmer 46,800 48.75 24.38 9.75 6.96
7.88 5.57 3.52 2.98
Try 2" Skimmer 46,800 41.67 20.84 8.33 5.95
7.28 5.15 3.26 2.75
Try 2 ½" Skimmer 46,800 36.85 18.43 7.37 5.26
6.85 4.84 3.06 2.59
Try 3" Skimmer 46,800 33.86 16.93 6.77 4.84
6.57 4.64 2.94 2.48
Try 4" Skimmer 46,800 29.23 14.62 5.85 4.18
Use 4.0" Skimmer w/ 4.0" Dia. Orifice 6.10 4.31 2.73 2.31
Try 5" Skimmer 46,800 28.50 14.25 5.70 4.07
6.02 4.26 2.69 2.28
Try 6" Skimmer 46,800 25.80 12.90 5.16 3.69
5.73 4.05 2.56 2.17
Faircloth Skimmer Orifice Design
(Information taken from J. W. Faircloth & Son, Inc Literature, Revision November 2007 )
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2-EC Basins.xlsPlotted 8/16/2018 Sheet: 2 of 2
Project: Granite Quarry
DPR Job No.: 17031
Location: Granite Quarry, NC
DPR ASSOCIATES
Riser Basin Design Worksheet
(per NCDEHNR Design Manual)
Prepared by:MPB
Checked by: HVN
Date: 10-19-17
Riser Sediment Basin w/ Skimmer #8 (NCDENR- Erosion Control # 6.64)
Pre-Development
Drainage Area "A" (ac) = 3.0
Runoff Coefficient, Pre Dev (C) = 0.30 (After demoliation, Seeded condition)
Rainfall Intensity "I" (in/hr) = 7.24 (for 5 min time of concentration)
Flow "Q10" (cfs) =6.5 (Q10=C*I*A)
Post-Development
Drainage Area "A" (ac) = 6.5
Runoff Coefficient, Post Dev (C) = 0.60
Rainfall Intensity "I" (in/hr) = 7.24 (for 5 min time of concentration)
Flow "Q10" (cfs) =28.2 (Q10=C*I*A)
Designed Flow "Q10" =28.2 cfs
Elevation
Storage Required (cf) =11,700 (V = 1,800 sf per acre of drainage areas )
Storage Provided =20,750 734.0 (measured @ storage depth)
Surface Area Required (sf) =9,177 (325 sf per cfs)
Surface Area Provided =13,000 736.0 (measure @ spillway)
Storage Dimensions:
Basin Side Slopes ( x : 1 ) =3.0
Storage Depth "H" (ft) =3.0
Bottom Dimension =731.0 (See Erosion Control plan,
Sediment Storage Dimension at "H" =for actual basin areas and storage provided)
Top of Embankment Dimension =737.0
Use the larger of the two conditions
Use Permanent BMP Outlet Structure and Spillway.
See BMP Plans & Calcs
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2-EC Basins.xlsPlotted 8/16/2018 Sheet: 1 of 2
Project: Granite Quarry
DPR Job No.: 17031
Location: Granite Quarry, NC
DPR ASSOCIATES
Riser Basin Design Worksheet
(per NCDEHNR Design Manual)
Prepared by:MPB
Checked by: HVN
Date: 10-19-17
Riser Sediment Basin w/ Skimmer #8 (NCDENR- Erosion Control # 6.64)
Skimmer Max. Capacity Size w/out Orifice (cf)24 hrs 2 days 5 days 7 days
1 1/2" skimmer 1,728 3,456 8,640 12,096
2" skimmer 3,283 6,566 16,415 22,981
2 1/2" skimmer 6,234 12,468 31,170 43,638
3" skimmer 9,774 19,548 48,870 68,418
4" skimmer 20,109 40,218 100,545 140,763
5" skimmer 32,832 65,664 164,160 229,824
6" skimmer 51,840 103,680 259,200 362,880
Factors (CF of flow per square inch of opening through a round orifice for the draw down times shown)
24 hrs 2 days 5 days 7 days
1 1/2" skimmer 960 1,920 4,800 6,720
2" skimmer 1,123 2,246 5,615 7,861
2 1/2" skimmer 1,270 2,540 6,350 8,890
3" skimmer 1,382 2,764 6,910 9,674
4" skimmer 1,601 3,202 8,005 11,207
5" skimmer 1,642 3,284 8,210 11,494
6" skimmer 1,814 3,628 9,070 12,698
Draw down time:24 hr 2 days 5 days 7 days
Volume Area (in^2)Area (in^2)Area (in^2)Area (in^2)
A = pi x d^2 / 4 , d = sq.rt.(A*4/pi)10-yr (cf)Orifice Dia. (in)Orifice Dia. (in)Orifice Dia. (in)Orifice Dia. (in)
Try 1 1/2" Skimmer 11,700 12.19 6.09 2.44 1.74
3.94 2.79 1.76 1.49
Try 2" Skimmer 11,700 10.42 5.21 2.08 1.49
Use 2.0" Skimmer w/ 2.0" Dia. Orifice 3.64 2.58 1.63 1.38
Try 2 ½" Skimmer 11,700 9.21 4.61 1.84 1.32
3.42 2.42 1.53 1.29
Try 3" Skimmer 11,700 8.47 4.23 1.69 1.21
3.28 2.32 1.47 1.24
Try 4" Skimmer 11,700 7.31 3.65 1.46 1.04
3.05 2.16 1.36 1.15
Try 5" Skimmer 11,700 7.13 3.56 1.43 1.02
3.01 2.13 1.35 1.14
Try 6" Skimmer 11,700 6.45 3.22 1.29 0.92
2.87 2.03 1.28 1.08
Faircloth Skimmer Orifice Design
(Information taken from J. W. Faircloth & Son, Inc Literature, Revision November 2007 )
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2-EC Basins.xlsPlotted 8/16/2018 Sheet: 2 of 2
Project: Granite Quarry
DPR Job No.: 17031
Location: Granite Quarry, NC
DPR ASSOCIATES
Riser Basin Design Worksheet
(per NCDEHNR Design Manual)
Prepared by:MPB
Checked by: HVN
Date: 10-19-17
Temporary Sediment Trap #9 (NCDENR- Erosion Control # 6.60)
Pre-Development
Drainage Area "A" (ac) = 2.5
Runoff Coefficient, Pre Dev (C) = 0.30 (After demoliation, Seeded condition)
Rainfall Intensity "I" (in/hr) = 7.24 (for 5 min time of concentration)
Flow "Q10" (cfs) =5.4 (Q10=C*I*A)
Elevation
Storage Required (cf) =4,500 (V = 1,800 sf per acre of drainage areas )
Storage Provided =4,050 734.0 (measured @ storage depth)
Surface Area Required (sf) =1,765 (325 sf per cfs)
Surface Area Provided =2,000 734.5 (measure @ spillway)
Storage Dimensions:
Basin Side Slopes ( x : 1 ) =2.0
Storage Depth "H" (ft) =3.0
Bottom Dimension =731.0 (See Erosion Control plan,
Sediment Storage Dimension at "H" =for actual basin areas and storage provided)
Top of Embankment Dimension =736.0
Spillway Length "L" (ft) =5.0 (Cw=3.0)
Spillway Crest Elevation "H" (ft) =3.5 734.5 (6" min. above storage depth)
Design High Water Depth "D" (ft) =0.5 735.0 (0.5 ft maximum)
Freeboard "F" (ft) =1.0 (1 ft minimum)
Dam Depth (ft) =5.0 736.0 (Top of Basin Elevation)
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2-EC Basins.xlsPlotted 8/16/2018 Sheet: 1 of 1
Project: Granite Quarry
DPR Job No.: 17031
Location: Granite Quarry, NC
DPR ASSOCIATES
Riser Basin Design Worksheet
(per NCDEHNR Design Manual)
Prepared by:MPB
Checked by: HVN
Date: 10-19-17
Temporary Sediment Trap #10 (NCDENR- Erosion Control # 6.60)
Pre-Development
Drainage Area "A" (ac) = 5.0
Runoff Coefficient, Pre Dev (C) = 0.30 (After demoliation, Seeded condition)
Rainfall Intensity "I" (in/hr) = 7.24 (for 5 min time of concentration)
Flow "Q10" (cfs) =10.9 (Q10=C*I*A)
Elevation
Storage Required (cf) =9,000 (V = 1,800 sf per acre of drainage areas )
Storage Provided =9,350 731.0 (measured @ storage depth)
Surface Area Required (sf) =3,530 (325 sf per cfs)
Surface Area Provided =4,100 731.0 (measure @ spillway)
Storage Dimensions:
Basin Side Slopes ( x : 1 ) =2.0
Storage Depth "H" (ft) =3.0
Bottom Dimension =728.0 (See Erosion Control plan,
Sediment Storage Dimension at "H" =for actual basin areas and storage provided)
Top of Embankment Dimension =733.0
Spillway Length "L" (ft) =10.0 (Cw=3.0)
Spillway Crest Elevation "H" (ft) =3.5 731.5 (6" min. above storage depth)
Design High Water Depth "D" (ft) =0.5 732.0 (0.5 ft maximum)
Freeboard "F" (ft) =1.0 (1 ft minimum)
Dam Depth (ft) =5.0 733.0 (Top of Basin Elevation)
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2-EC Basins.xlsPlotted 8/16/2018 Sheet: 1 of 1
Project: Granite Quarry
DPR Job No.: 17031
Location: Granite Quarry, NC
DPR ASSOCIATES
Riser Basin Design Worksheet
(per NCDEHNR Design Manual)
Prepared by:MPB
Checked by: HVN
Date: 10-19-17
Temporary Sediment Trap #11 (NCDENR- Erosion Control # 6.60)
Pre-Development
Drainage Area "A" (ac) = 8.5
Runoff Coefficient, Pre Dev (C) = 0.30 (After demoliation, Seeded condition)
Rainfall Intensity "I" (in/hr) = 7.24 (for 5 min time of concentration)
Flow "Q10" (cfs) =18.5 (Q10=C*I*A)
Elevation
Storage Required (cf) =15,300 (V = 1,800 sf per acre of drainage areas )
Storage Provided =16,105 726.0 (measured @ storage depth)
Surface Area Required (sf) =6,000 (325 sf per cfs)
Surface Area Provided =6,600 726.5 (measure @ spillway)
Storage Dimensions:
Basin Side Slopes ( x : 1 ) =2.0
Storage Depth "H" (ft) =3.0
Bottom Dimension =723.0 (See Erosion Control plan,
Sediment Storage Dimension at "H" =for actual basin areas and storage provided)
Top of Embankment Dimension =728.0
Spillway Length "L" (ft) =16.0 (Cw=3.0)
Spillway Crest Elevation "H" (ft) =3.5 726.5 (6" min. above storage depth)
Design High Water Depth "D" (ft) =0.5 727.0 (0.5 ft maximum)
Freeboard "F" (ft) =1.0 (1 ft minimum)
Dam Depth (ft) =5.0 728.0 (Top of Basin Elevation)
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2-EC Basins.xlsPlotted 8/16/2018 Sheet: 1 of 1
Project: Granite Quarry
DPR Job No.: 17031
Location: Granite Quarry, NC
DPR ASSOCIATES
Riser Basin Design Worksheet
(per NCDEHNR Design Manual)
Prepared by:MPB
Checked by: HVN
Date: 10-19-17
Temporary Sediment Trap #12 (NCDENR- Erosion Control # 6.60)
Pre-Development
Drainage Area "A" (ac) = 5.0
Runoff Coefficient, Pre Dev (C) = 0.30 (After demoliation, Seeded condition)
Rainfall Intensity "I" (in/hr) = 7.24 (for 5 min time of concentration)
Flow "Q10" (cfs) =10.9 (Q10=C*I*A)
Elevation
Storage Required (cf) =9,000 (V = 1,800 sf per acre of drainage areas )
Storage Provided =9,100 728.0 (measured @ storage depth)
Surface Area Required (sf) =3,530 (325 sf per cfs)
Surface Area Provided =3,900 728.5 (measure @ spillway)
Storage Dimensions:
Basin Side Slopes ( x : 1 ) =2.0
Storage Depth "H" (ft) =3.0
Bottom Dimension =725.0 (See Erosion Control plan,
Sediment Storage Dimension at "H" =for actual basin areas and storage provided)
Top of Embankment Dimension =730.0
Spillway Length "L" (ft) =10.0 (Cw=3.0)
Spillway Crest Elevation "H" (ft) =3.5 728.5 (6" min. above storage depth)
Design High Water Depth "D" (ft) =0.5 729.0 (0.5 ft maximum)
Freeboard "F" (ft) =1.0 (1 ft minimum)
Dam Depth (ft) =5.0 730.0 (Top of Basin Elevation)
T:\PROJECTS\2017 PROJECTS\17031 The Village At Granite - LGI\PHASE 2\CALCS\STORM & EC\17031-PH2-EC Basins.xlsPlotted 8/16/2018 Sheet: 1 of 1