Erosion Control Report
Wilmington CNG Station
Erosion Control Report
Erosion and Sediment Control Calculation Report / February 2021
Erosion Control Calculation Report
WILMINGTON CNG STATION
NEW HANOVER, NORTH CAROLINA
PNG-20000
February 15, 2021
DESIGNED BY: KIRK SHEARER
REVIEWED BY: BRANDON FINCH, PE
2905 MERIDIAN PARKWAY
DURHAM, NORTH CAROLINA 27713
NC LIC. # C-0293
Sedimentation and Erosion Control Report Then John R. McAdams Company
Piedmont Natural Gas 2/15/2021 Wilmington CNG Station
Wilmington, North Carolina
i
TABLE OF CONTENTS SECTION I ..................................................................................................................................... 3
1.0 PROJECT DESCRIPTION ................................................................................................... 3
2.0 EROSION AND SEDIMENT CONTROL MEASURES .................................................... 3
2.1 Silt Fence ................................................................................................................................................... 3 2.2 Check Dam ................................................................................................................................................ 3 3.0 VEGETATIVE STABILIZATION ...................................................................................... 3
4.0 MAINTENANCE ................................................................................................................. 4
5.0 EROSION CONTROL CALCULATION METHODOLOGY ............................................ 4
5.1 Silt Fence ................................................................................................................................................... 4 5.2 Check Dam ................................................................................................................................................ 4 LIST OF APPENDICES ................................................................................................................. 5
o Project Maps .................................................................................................................................................. 5
o NOAA PFDS Rainfall Data ........................................................................................................................... 5
o Culvert and Dissipator Calculations .............................................................................................................. 5
o Permanent Ditch Calculations ....................................................................................................................... 5
o Ditch Liner Calculations ................................................................................................................................ 5
o Deed ............................................................................................................................................................... 5
Sedimentation and Erosion Control Report Then John R. McAdams Company
Piedmont Natural Gas 2/15/2021 Wilmington CNG Station
Wilmington, North Carolina
ii
Sedimentation and Erosion Control Report Then John R. McAdams Company Piedmont Natural Gas 2/15/2021 Wilmington CNG Station Wilmington, North Carolina
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WILMINGTON CNG STATION
EROSION CONTROL PERMIT
WILMINGTON, NORTH CAROLINA
SEDIMENTATION AND EROSION CONTROL REPORT
SECTION I
1.0 PROJECT DESCRIPTION
This site is located at 141 Sutton Steam Plant Road in Wilmington, North Carolina. Piedmont Natural Gas (PNG) is seeking to build a new compressed natural gas (CNG) fueling station. Proposed improvements include new fueling stations with associated canopy, a CNG compressor
pad, driveway and paving improvements, along with supporting utility and stormwater
management improvements. The disturbed area for this project is 2.66 acres. 2.0 EROSION AND SEDIMENT CONTROL MEASURES All vegetative practices and erosion and sediment control features shall be designed, constructed and maintained to control runoff resulting from the 2 and 10-year frequency storms. Supporting design calculations are attached. Plan-view drawings with details are also provided.
2.1 Silt Fence Silt fences will be provided down gradient of the proposed site grading at the locations shown on the drawings. The sediment fences will act as a filter for sediment laden runoff sheet flowing
from slopes or small areas that cannot be directed to a temporary sediment basin. Silt fence
outlets will be placed at any low points along the silt fence to allow collected runoff to pass through without overwhelming the fencing. 2.2 Check Dam
A small temporary stone dam constructed across drainage way. To reduce erosion in a drainage channel by reducing the velocity of flow.
3.0 VEGETATIVE STABILIZATION
Sedimentation and Erosion Control Report Then John R. McAdams Company Piedmont Natural Gas 2/15/2021 Wilmington CNG Station Wilmington, North Carolina
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Vegetative cover shall be re-established within 14 calendar days or less as per NPDES requirements after completion of the activity. Temporary and permanent seeding specifications are included on the plans.
4.0 MAINTENANCE All erosion and sedimentation control measures shall be checked for stability and operation
following every runoff-producing rainfall but in no case less than once every week. Any needed repairs will be made immediately to maintain all measures as designed. 5.0 EROSION CONTROL CALCULATION METHODOLOGY
5.1 Silt Fence
Silt fence proposed meets the ¼ acre per 100 lf of fence requirements in the North Carolina Erosion and Sediment Control Planning and Design Manual. Gravel silt fence outlets are to be installed at low points in the fence lines as indicated on the plans.
5.2 Check Dam
Inspect check dams and channels at least weekly and after each significant (1/2 inch or greater)
rainfall event and repair immediately. Clean out sediment straw, limbs, or other debris that could
clog the channel when needed.
Sedimentation and Erosion Control Report Then John R. McAdams Company Piedmont Natural Gas 2/15/2021 Wilmington CNG Station Wilmington, North Carolina
5
LIST OF APPENDICES
o Project Maps o NOAA PFDS Rainfall Data o Culvert and Dissipator Design
o Permanent Ditch Design
o Ditch Liner Calculations
o Deed
Sedimentation and Erosion Control Report Then John R. McAdams Company Piedmont Natural Gas 2/15/2021 Wilmington CNG Station Wilmington, North Carolina
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APPENDIX A: PROJECT MAPS
The John R. McAdams Company, Inc.
2905 Meridian Parkway
Durham, NC 27713
phone 919. 361. 5000
fax 919. 361. 2269
license number: C-0293, C-187
www.mcadamsco.com
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PIEDMONT NATURAL GAS
DRAINAGE AREA DELINEATION MAP
GRAPHIC SCALE
0 20 40 80
1 inch = 40 ft.
CONTRACTOR SHALL NOTIFY "NC811" (811) OR (1-800-632-4949) AT
LEAST 3 FULL BUSINESS DAYS PRIOR TO BEGINNING CONSTRUCTION
OR EXCAVATION TO HAVE EXISTING UTILITIES LOCATED.
CONTRACTOR SHALL CONTACT ANY LOCAL UTILITIES THAT PROVIDE
THEIR OWN LOCATOR SERVICES INDEPENDENT OF "NC811".
REPORT ANY DISCREPANCIES TO THE ENGINEER IMMEDIATELY.
R
Sedimentation and Erosion Control Report Then John R. McAdams Company Piedmont Natural Gas 2/15/2021 Wilmington CNG Station Wilmington, North Carolina
7
APPENDIX B: NOAA PFDS RAINFALL DATA
NOAA Atlas 14, Volume 2, Version 3
Location name: Wilmington, North Carolina,
USA*
Latitude: 34.235°, Longitude: -77.946°
Elevation: 32.65 ft**
* source: ESRI Maps ** source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF_tabular | PF_graphical | Maps_&_aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/hour)1
Duration Average recurrence interval (years)
1 2 5 10 25 50 100 200 500 1000
5-min 6.26(5.86‑6.76)7.44(6.95‑8.02)8.71(8.11‑9.36)9.70(9.00‑10.4)11.0(10.1‑11.7)11.9(10.9‑12.8)12.9(11.8‑13.8)13.8(12.6‑14.9)15.1(13.6‑16.2)16.1(14.4‑17.4)
10-min 5.00
(4.67‑5.39)
5.95
(5.55‑6.41)
6.97
(6.50‑7.49)
7.76
(7.20‑8.33)
8.73
(8.06‑9.35)
9.47
(8.71‑10.2)
10.2
(9.35‑11.0)
11.0
(9.96‑11.8)
11.9
(10.7‑12.9)
12.7
(11.3‑13.7)
15-min 4.17
(3.90‑4.49)
4.99
(4.65‑5.37)
5.88
(5.48‑6.32)
6.54
(6.07‑7.03)
7.38
(6.82‑7.90)
8.00
(7.35‑8.58)
8.62
(7.88‑9.24)
9.22
(8.38‑9.90)
10.0
(9.00‑10.8)
10.6
(9.46‑11.5)
30-min 2.86
(2.67‑3.08)
3.45
(3.21‑3.71)
4.18
(3.89‑4.49)
4.74
(4.40‑5.09)
5.46
(5.05‑5.85)
6.02
(5.54‑6.46)
6.60
(6.03‑7.08)
7.18
(6.52‑7.71)
7.96
(7.16‑8.58)
8.60
(7.66‑9.27)
60-min 1.78
(1.67‑1.92)
2.16
(2.02‑2.33)
2.68
(2.50‑2.88)
3.09
(2.86‑3.32)
3.64
(3.36‑3.90)
4.08
(3.75‑4.38)
4.54
(4.16‑4.88)
5.03
(4.57‑5.41)
5.71
(5.14‑6.16)
6.27
(5.59‑6.77)
2-hr 1.06
(0.974‑1.15)
1.29
(1.19‑1.40)
1.64
(1.51‑1.79)
1.93
(1.78‑2.11)
2.36
(2.16‑2.57)
2.72
(2.48‑2.96)
3.12
(2.83‑3.40)
3.56
(3.20‑3.86)
4.21
(3.74‑4.58)
4.77
(4.20‑5.20)
3-hr 0.751
(0.695‑0.822)
0.914
(0.844‑0.999)
1.17
(1.08‑1.28)
1.39
(1.28‑1.52)
1.72
(1.57‑1.87)
2.01
(1.82‑2.19)
2.33
(2.10‑2.53)
2.69
(2.40‑2.91)
3.23
(2.85‑3.51)
3.71
(3.23‑4.03)
6-hr 0.467(0.432‑0.512)0.568(0.525‑0.623)0.728(0.671‑0.797)0.868(0.797‑0.948)1.08(0.982‑1.17)1.26(1.14‑1.37)1.47(1.32‑1.59)1.70(1.51‑1.85)2.05(1.80‑2.23)2.37(2.05‑2.58)
12-hr 0.272(0.249‑0.300)0.331(0.303‑0.364)0.427(0.390‑0.469)0.511(0.465‑0.561)0.638(0.576‑0.699)0.752(0.675‑0.822)0.881(0.784‑0.962)1.03(0.904‑1.12)1.25(1.09‑1.37)1.45(1.24‑1.59)
24-hr 0.160
(0.146‑0.178)
0.194
(0.177‑0.217)
0.251
(0.228‑0.280)
0.301
(0.273‑0.335)
0.379
(0.340‑0.420)
0.448
(0.398‑0.497)
0.526
(0.463‑0.584)
0.616
(0.534‑0.684)
0.754
(0.640‑0.844)
0.877
(0.731‑0.986)
2-day 0.094
(0.086‑0.104)
0.114
(0.104‑0.126)
0.146
(0.134‑0.162)
0.174
(0.159‑0.193)
0.217
(0.196‑0.241)
0.255
(0.227‑0.283)
0.297
(0.262‑0.331)
0.346
(0.300‑0.386)
0.419
(0.357‑0.472)
0.484
(0.404‑0.547)
3-day 0.067
(0.061‑0.074)
0.081
(0.074‑0.089)
0.103
(0.094‑0.114)
0.122
(0.111‑0.135)
0.151
(0.136‑0.167)
0.176
(0.157‑0.195)
0.204
(0.181‑0.227)
0.236
(0.206‑0.263)
0.284
(0.243‑0.319)
0.326
(0.274‑0.368)
4-day 0.053
(0.049‑0.059)
0.064
(0.059‑0.071)
0.081
(0.074‑0.090)
0.096
(0.087‑0.106)
0.118
(0.106‑0.130)
0.137
(0.122‑0.151)
0.158
(0.140‑0.175)
0.181
(0.158‑0.201)
0.216
(0.186‑0.242)
0.247
(0.209‑0.279)
7-day 0.035
(0.032‑0.038)
0.042
(0.039‑0.046)
0.053
(0.049‑0.058)
0.062
(0.057‑0.068)
0.075
(0.069‑0.082)
0.086
(0.079‑0.094)
0.099
(0.089‑0.108)
0.112
(0.100‑0.123)
0.131
(0.115‑0.145)
0.148
(0.128‑0.165)
10-day 0.028(0.026‑0.030)0.033(0.031‑0.036)0.041(0.038‑0.045)0.048(0.044‑0.052)0.057(0.053‑0.062)0.065(0.060‑0.071)0.074(0.067‑0.081)0.083(0.075‑0.091)0.097(0.086‑0.107)0.109(0.094‑0.121)
20-day 0.019(0.017‑0.020)0.022(0.021‑0.024)0.027(0.025‑0.029)0.031(0.029‑0.033)0.036(0.034‑0.039)0.041(0.038‑0.044)0.046(0.042‑0.050)0.051(0.046‑0.056)0.059(0.053‑0.064)0.065(0.057‑0.072)
30-day 0.015
(0.014‑0.016)
0.018
(0.017‑0.019)
0.022
(0.020‑0.023)
0.025
(0.023‑0.026)
0.029
(0.027‑0.031)
0.032
(0.030‑0.034)
0.035
(0.033‑0.038)
0.039
(0.035‑0.042)
0.044
(0.039‑0.047)
0.047
(0.042‑0.052)
45-day 0.013
(0.012‑0.013)
0.015
(0.014‑0.016)
0.018
(0.017‑0.019)
0.020
(0.019‑0.021)
0.023
(0.022‑0.024)
0.025
(0.024‑0.027)
0.028
(0.026‑0.030)
0.031
(0.028‑0.033)
0.034
(0.031‑0.037)
0.037
(0.033‑0.040)
60-day 0.011
(0.011‑0.012)
0.013
(0.013‑0.014)
0.016
(0.015‑0.017)
0.017
(0.016‑0.019)
0.020
(0.019‑0.021)
0.022
(0.020‑0.023)
0.024
(0.022‑0.025)
0.026
(0.024‑0.027)
0.028
(0.026‑0.030)
0.030
(0.027‑0.032)
1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
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PF graphical
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Maps & aerials
Small scale terrain
Large scale terrain
Large scale map
+
–
3km
2mi
+
–
100km
60mi
+
–
100km
60mi
Large scale aerial
Back to Top
US Department of CommerceNational Oceanic and Atmospheric AdministrationNational Weather ServiceNational Water Center1325 East West Highway
Silver Spring, MD 20910
Questions?: HDSC.Questions@noaa.gov
Disclaimer
+
–
100km
60mi
Sedimentation and Erosion Control Report Then John R. McAdams Company Piedmont Natural Gas 2/15/2021 Wilmington CNG Station Wilmington, North Carolina
8
APPENDIX C: CULVERT AND DISSIPATOR CALCULATIONS
Culvert Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc.Monday, Feb 15 2021
CULVERT
Invert Elev Dn (ft)= 22.00
Pipe Length (ft)= 92.00
Slope (%)= 1.00
Invert Elev Up (ft)= 22.92
Rise (in)= 18.0
Shape= Circular
Span (in)= 18.0
No. Barrels= 1
n-Value= 0.013
Culvert Type= Circular Concrete
Culvert Entrance= Square edge w/headwall (C)
Coeff. K,M,c,Y,k= 0.0098, 2, 0.0398, 0.67, 0.5
Embankment
Top Elevation (ft)= 26.40
Top Width (ft)= 44.00
Crest Width (ft)= 10.00
Calculations
Qmin (cfs)= 4.69
Qmax (cfs)= 4.69
Tailwater Elev (ft)= (dc+D)/2
Highlighted
Qtotal (cfs)= 4.69
Qpipe (cfs)= 4.69
Qovertop (cfs)= 0.00
Veloc Dn (ft/s)= 3.18
Veloc Up (ft/s)= 4.67
HGL Dn (ft)= 23.17
HGL Up (ft)= 23.75
Hw Elev (ft)= 24.15
Hw/D (ft)= 0.82
Flow Regime= Inlet Control
Project:Date:2/10/2021
Project Number:Calculated By: KAS
Outlet Number:
Outlet flowrate =4.69 cfs
Pipe diameter = 18 inches
Number of pipes = 1
Pipe separation = 0 feet
Outlet Velocity = 3.18 ft/sec
Zone from graph above =1
Outlet pipe diameter 18 in.Length =6.0 ft.
Outlet flowrate 4.7 cfs Width =3.9 ft.
Outlet velocity 3.2 ft/sec Stone diameter =3 in.
Material =Class A Thickness =12 in.
Zone Material Diameter Thickness Length Width
1 Class A 3 12 4 x D(o)3 x D(o)
2 Class B 6 18 6 x D(o)3 x D(o)
3 Class I 13 24 8 x D(o)3 x D(o)
4 Class I 13 24 8 x D(o)3 x D(o)
5 Class II 23 36 10 x D(o)3 x D(o)
6 Class II 23 36 10 x D(o)3 x D(o)
7
1. Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual
2. Outlet velocity based on full-flow velocity
DESIGN OF RIPRAP OUTLET PROTECTION WORKSHEET
PNG Wilmington
PNG-20000
Culvert
Special study required
3.2 ft/sec
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10
Ve
l
o
c
i
t
y
(
f
t
/
s
e
c
)
Pipe diameter (ft)
Figure 8.06.b.1
Zone 1 Zone 2
Zone 3
Zone 4
Zone 5
Zone 6
Zone 7
Sedimentation and Erosion Control Report Then John R. McAdams Company Piedmont Natural Gas 2/15/2021 Wilmington CNG Station Wilmington, North Carolina
9
APPENDIX D: PERMANENT DITCH CALCULATIONS
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc.Monday, Feb 15 2021
PD-1
Triangular
Side Slopes (z:1)= 4.00, 4.00
Total Depth (ft)= 1.25
Invert Elev (ft)= 221.00
Slope (%)= 1.00
N-Value= 0.035
Calculations
Compute by:Known Q
Known Q (cfs)= 3.77
Highlighted
Depth (ft)= 0.69
Q (cfs)= 3.770
Area (sqft)= 1.90
Velocity (ft/s)= 1.98
Wetted Perim (ft)= 5.69
Crit Depth, Yc (ft)= 0.57
Top Width (ft)= 5.52
EGL (ft)= 0.75
0 1 2 3 4 5 6 7 8 9 10 11 12
Elev (ft)Depth (ft)Section
220.50-0.50
221.000.00
221.500.50
222.001.00
222.501.50
223.002.00
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc.Monday, Feb 15 2021
PD-2
Triangular
Side Slopes (z:1)= 4.00, 4.00
Total Depth (ft)= 1.25
Invert Elev (ft)= 22.92
Slope (%)= 1.18
N-Value= 0.035
Calculations
Compute by:Known Q
Known Q (cfs)= 4.69
Highlighted
Depth (ft)= 0.72
Q (cfs)= 4.690
Area (sqft)= 2.07
Velocity (ft/s)= 2.26
Wetted Perim (ft)= 5.94
Crit Depth, Yc (ft)= 0.62
Top Width (ft)= 5.76
EGL (ft)= 0.80
0 1 2 3 4 5 6 7 8 9 10 11 12
Elev (ft)Depth (ft)Section
22.00-0.92
22.50-0.42
23.000.08
23.500.58
24.001.08
24.501.58
25.002.08
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc.Monday, Feb 15 2021
PD-3
Triangular
Side Slopes (z:1)= 4.00, 4.00
Total Depth (ft)= 1.00
Invert Elev (ft)= 25.00
Slope (%)= 1.95
N-Value= 0.035
Calculations
Compute by:Known Q
Known Q (cfs)= 2.21
Highlighted
Depth (ft)= 0.50
Q (cfs)= 2.210
Area (sqft)= 1.00
Velocity (ft/s)= 2.21
Wetted Perim (ft)= 4.12
Crit Depth, Yc (ft)= 0.46
Top Width (ft)= 4.00
EGL (ft)= 0.58
0 1 2 3 4 5 6 7 8 9 10
Elev (ft)Depth (ft)Section
24.50-0.50
25.000.00
25.500.50
26.001.00
26.501.50
27.002.00
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc.Monday, Feb 15 2021
PD-4
Triangular
Side Slopes (z:1)= 4.00, 4.00
Total Depth (ft)= 1.10
Invert Elev (ft)= 24.00
Slope (%)= 2.19
N-Value= 0.035
Calculations
Compute by:Known Q
Known Q (cfs)= 3.36
Highlighted
Depth (ft)= 0.57
Q (cfs)= 3.360
Area (sqft)= 1.30
Velocity (ft/s)= 2.59
Wetted Perim (ft)= 4.70
Crit Depth, Yc (ft)= 0.54
Top Width (ft)= 4.56
EGL (ft)= 0.67
0 1 2 3 4 5 6 7 8 9 10 11
Elev (ft)Depth (ft)Section
23.50-0.50
24.000.00
24.500.50
25.001.00
25.501.50
26.002.00
Reach (ft)
Channel Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc.Monday, Feb 15 2021
PD-5
Triangular
Side Slopes (z:1)= 4.00, 4.00
Total Depth (ft)= 1.50
Invert Elev (ft)= 223.00
Slope (%)= 1.67
N-Value= 0.035
Calculations
Compute by:Known Q
Known Q (cfs)= 11.48
Highlighted
Depth (ft)= 0.94
Q (cfs)= 11.48
Area (sqft)= 3.53
Velocity (ft/s)= 3.25
Wetted Perim (ft)= 7.75
Crit Depth, Yc (ft)= 0.88
Top Width (ft)= 7.52
EGL (ft)= 1.10
0 2 4 6 8 10 12 14 16
Elev (ft)Depth (ft)Section
222.50-0.50
223.000.00
223.500.50
224.001.00
224.501.50
225.002.00
Reach (ft)
Sedimentation and Erosion Control Report Then John R. McAdams Company Piedmont Natural Gas 2/15/2021 Wilmington CNG Station Wilmington, North Carolina
10
APPENDIX E: DITCH LINER CALCULATIONS
Project Name:Wilmington CNG Station Date:2/11/2021
Project Number:PNG-20000 Calculated By:KAS
Channel Number:PD-1
I. FLOW CALCULATIONS
Drainage Area =0.46 acres
SCS CN =92
Rational C =0.84
TC =5.00 min
I2 =7.44 in/hr Calculated values are for the Raleigh-Durham area. For other areas, values will have to be input manually.
I10 =9.70 in/hr
Q2 =2.87 cfs
Q10 =3.75 cfs
II. SWALE CALCULATIONS
Proposed Channel Section
Longitudinal Slope =1.00%
Left Sideslope =4.00 H:V
Right Sideslope =4.00 H:V
Maximum Vel. =4.50 ft/s
Bottom Width =0.00 ft
10-Year Storm Calculations (for Permanent Liner)
Match Manning's "n" to Calculated "n" and adjust Depth until Capacity matches Flow (Q10).
Depth Flow Area
Wetted
Perimeter
Hydraulic
Radius Velocity VR Flow (Q10)Capacity Shear Stress
Liner Description/
Selection Calculated
[ft][ft2][ft][ft][ft/sec][ft2/sec][cfs][cfs][lb/ft^2]"n"
0.059 1.25 6.25 10.31 0.61 1.80 1.09 3.75 11.28 0.78 Tall Fescue 0.059
0.034 0.4 0.64 3.30 0.19 1.46 n/a 3.75 0.94 0.25 ERONET P300 0.034
------->NO PERMANENT LINER REQUIRED
------->VELOCITY IS OKAY
------->SHEAR STRESS IS OKAY
2-Year Storm Calculations (for Temporary Liner)
Depth Flow Area Wetted PerimeterHydraulic Rad.Velocity VR Flow (Q2)Capacity Shear Stress Calculated
[ft][ft2][ft][ft][ft/sec][ft2/sec][cfs][cfs][lb/ft^2]"n"
0.022 0.75 2.25 6.18 0.36 3.44 n/a 2.87 7.74 0.47 Bare Earth -
0.055 1.05 4.41 8.66 0.51 1.72 n/a 2.87 7.60 0.66 ERONET S75 0.043
------->CHANNEL UNSTABLE - TEMPORARY LINER REQUIRED
------->VELOCITY IS OKAY
------->SHEAR STRESS IS OKAY
Liner Longevity ->
T = Top; B = Bottom; M = Middle
T = Top; B = Bottom; M = Middle
100% Straw Fiber - 0.5lb/sy T(only): Lightweight photodegradable - 1.5lb/10000sf 5.0 1.55
Description
Matrix Netting Allowabe Unvegetated Allowable Partially Vegetated
Velocity (f/s)Shear Stress [lb/ft^2]
Allowable Partially Vegetated
Shear Stress [lb/ft^2]
8.0
Temporary Liner Specifications -ERONET S75
Matrix Netting
100% UV Stable
Polypropylene Fiber - 0.7lb/sy
T: UV-Stabilized Polypropylene - 5lb/1000sf
B: UV-Stabilized Polypropylene - 3lb/1000sf
Allowabe Partially Vegetated
Velocity (f/s)
9.0
Manning's "n"
Manning's "n"
EROSION CONTROL CHANNEL DESIGN
12 Months
Permanent Liner Specifications -ERONET P300
C = 0.020 x CN - 1.0
Conservative assumption
For established grass lined channel
For newly graded areas, HSG 'A' soils
Project Name:Wilmington CNG Station Date:2/11/2021
Project Number:PNG-20000 Calculated By:KAS
Channel Number:PD-2
I. FLOW CALCULATIONS
Drainage Area =0.75 acres
SCS CN =92
Rational C =0.84
TC =5.00 min
I2 =7.44 in/hr Calculated values are for the Raleigh-Durham area. For other areas, values will have to be input manually.
I10 =9.70 in/hr
Q2 =4.69 cfs
Q10 =6.11 cfs
II. SWALE CALCULATIONS
Proposed Channel Section
Longitudinal Slope =1.18%
Left Sideslope =4.00 H:V
Right Sideslope =4.00 H:V
Maximum Vel. =4.50 ft/s
Bottom Width =0.00 ft
10-Year Storm Calculations (for Permanent Liner)
Match Manning's "n" to Calculated "n" and adjust Depth until Capacity matches Flow (Q10).
Depth Flow Area
Wetted
Perimeter
Hydraulic
Radius Velocity VR Flow (Q10)Capacity Shear Stress
Liner Description/
Selection Calculated
[ft][ft2][ft][ft][ft/sec][ft2/sec][cfs][cfs][lb/ft^2]"n"
0.165 0.7 1.96 5.77 0.34 0.48 0.16 6.11 0.93 0.52 Tall Fescue 0.165
0.034 0.5 1.00 4.12 0.24 1.85 n/a 6.11 1.85 0.37 ERONET P300 0.034
------->NO PERMANENT LINER REQUIRED
------->VELOCITY IS OKAY
------->SHEAR STRESS IS OKAY
2-Year Storm Calculations (for Temporary Liner)
Depth Flow Area Wetted PerimeterHydraulic Rad.Velocity VR Flow (Q2)Capacity Shear Stress Calculated
[ft][ft2][ft][ft][ft/sec][ft2/sec][cfs][cfs][lb/ft^2]"n"
0.022 0.4 0.64 3.30 0.19 2.46 n/a 4.69 1.57 0.29 Bare Earth -
0.055 0.5 1.00 4.12 0.24 1.14 n/a 4.69 1.14 0.37 ERONET S75 0.055
------->CHANNEL UNSTABLE - TEMPORARY LINER REQUIRED
------->VELOCITY IS OKAY
------->SHEAR STRESS IS OKAY
Liner Longevity ->
T = Top; B = Bottom; M = Middle
T = Top; B = Bottom; M = Middle
8.0
100% Straw Fiber - 0.5lb/sy T(only): Lightweight photodegradable - 1.5lb/10000sf 5.0 1.55
Matrix Netting Allowabe Unvegetated Allowable Partially Vegetated
Velocity (f/s)Shear Stress [lb/ft^2]
Temporary Liner Specifications -ERONET S75
Manning's "n"Description
12 Months
Permanent Liner Specifications -ERONET P300
Matrix Netting Allowabe Partially Vegetated Allowable Partially Vegetated
Velocity (f/s)Shear Stress [lb/ft^2]
100% UV Stable
Polypropylene Fiber - 0.7lb/sy
T: UV-Stabilized Polypropylene - 5lb/1000sf
B: UV-Stabilized Polypropylene - 3lb/1000sf 9.0
Manning's "n"
EROSION CONTROL CHANNEL DESIGN
For newly graded areas, HSG 'A' soils
C = 0.020 x CN - 1.0
Conservative assumption
For established grass lined channel
Project Name:Wilmington CNG Station Date:2/11/2021
Project Number:PNG-20000 Calculated By:KAS
Channel Number:PD-3
I. FLOW CALCULATIONS
Drainage Area =0.27 acres
SCS CN =92
Rational C =0.84
TC =5.00 min
I2 =7.44 in/hr Calculated values are for the Raleigh-Durham area. For other areas, values will have to be input manually.
I10 =9.70 in/hr
Q2 =1.69 cfs
Q10 =2.20 cfs
II. SWALE CALCULATIONS
Proposed Channel Section
Longitudinal Slope =1.95%
Left Sideslope =3.00 H:V
Right Sideslope =4.00 H:V
Maximum Vel. =4.50 ft/s
Bottom Width =0.00 ft
10-Year Storm Calculations (for Permanent Liner)
Match Manning's "n" to Calculated "n" and adjust Depth until Capacity matches Flow (Q10).
Depth Flow Area
Wetted
Perimeter
Hydraulic
Radius Velocity VR Flow (Q10)Capacity Shear Stress
Liner Description/
Selection Calculated
[ft][ft2][ft][ft][ft/sec][ft2/sec][cfs][cfs][lb/ft^2]"n"
0.110 0.75 1.97 5.46 0.36 0.96 0.34 2.20 1.88 0.91 Tall Fescue 0.110
0.032 0.75 1.97 5.46 0.36 3.28 n/a 2.20 6.46 0.91 ERONET P300 0.032
------->NO PERMANENT LINER REQUIRED
------->VELOCITY IS OKAY
------->SHEAR STRESS IS OKAY
2-Year Storm Calculations (for Temporary Liner)
Depth Flow Area Wetted PerimeterHydraulic Rad.Velocity VR Flow (Q2)Capacity Shear Stress Calculated
[ft][ft2][ft][ft][ft/sec][ft2/sec][cfs][cfs][lb/ft^2]"n"
0.022 0.4 0.56 2.91 0.19 3.14 n/a 1.69 1.76 0.49 Bare Earth -
0.055 0.5 0.88 3.64 0.24 1.46 n/a 1.69 1.28 0.61 ERONET S75 0.055
------->CHANNEL UNSTABLE - TEMPORARY LINER REQUIRED
------->VELOCITY IS OKAY
------->SHEAR STRESS IS OKAY
Liner Longevity ->
T = Top; B = Bottom; M = Middle
T = Top; B = Bottom; M = Middle
8.0
100% Straw Fiber - 0.5lb/sy T(only): Lightweight photodegradable - 1.5lb/10000sf 5.0 1.55
Matrix Netting Allowabe Unvegetated Allowable Partially Vegetated
Velocity (f/s)Shear Stress [lb/ft^2]
Temporary Liner Specifications -ERONET S75
Manning's "n"Description
12 Months
Permanent Liner Specifications -ERONET P300
Matrix Netting Allowabe Partially Vegetated Allowable Partially Vegetated
Velocity (f/s)Shear Stress [lb/ft^2]
100% UV Stable
Polypropylene Fiber - 0.7lb/sy
T: UV-Stabilized Polypropylene - 5lb/1000sf
B: UV-Stabilized Polypropylene - 3lb/1000sf 9.0
Manning's "n"
EROSION CONTROL CHANNEL DESIGN
For newly graded areas, HSG 'A' soils
C = 0.020 x CN - 1.0
Conservative assumption
For established grass lined channel
Project Name:Wilmington CNG Station Date:2/11/2021
Project Number:PNG-20000 Calculated By:KAS
Channel Number:PD-4
I. FLOW CALCULATIONS
Drainage Area =0.41 acres
SCS CN =92
Rational C =0.84
TC =5.00 min
I2 =7.44 in/hr Calculated values are for the Raleigh-Durham area. For other areas, values will have to be input manually.
I10 =9.70 in/hr
Q2 =2.56 cfs
Q10 =3.34 cfs
II. SWALE CALCULATIONS
Proposed Channel Section
Longitudinal Slope =2.19%
Left Sideslope =4.00 H:V
Right Sideslope =3.00 H:V
Maximum Vel. =4.50 ft/s
Bottom Width =0.00 ft
10-Year Storm Calculations (for Permanent Liner)
Match Manning's "n" to Calculated "n" and adjust Depth until Capacity matches Flow (Q10).
Depth Flow Area
Wetted
Perimeter
Hydraulic
Radius Velocity VR Flow (Q10)Capacity Shear Stress
Liner Description/
Selection Calculated
[ft][ft2][ft][ft][ft/sec][ft2/sec][cfs][cfs][lb/ft^2]"n"
0.110 0.75 1.97 5.46 0.36 1.01 0.36 3.34 1.99 1.02 Tall Fescue 0.110
0.032 0.75 1.97 5.46 0.36 3.48 n/a 3.34 6.85 1.02 ERONET P300 0.032
------->NO PERMANENT LINER REQUIRED
------->VELOCITY IS OKAY
------->SHEAR STRESS IS OKAY
2-Year Storm Calculations (for Temporary Liner)
Depth Flow Area Wetted PerimeterHydraulic Rad.Velocity VR Flow (Q2)Capacity Shear Stress Calculated
[ft][ft2][ft][ft][ft/sec][ft2/sec][cfs][cfs][lb/ft^2]"n"
0.022 0.4 0.56 2.91 0.19 3.33 n/a 2.56 1.86 0.55 Bare Earth -
0.055 0.5 0.88 3.64 0.24 1.54 n/a 2.56 1.35 0.68 ERONET S75 0.055
------->CHANNEL UNSTABLE - TEMPORARY LINER REQUIRED
------->VELOCITY IS OKAY
------->SHEAR STRESS IS OKAY
Liner Longevity ->
T = Top; B = Bottom; M = Middle
T = Top; B = Bottom; M = Middle
Manning's "n"
EROSION CONTROL CHANNEL DESIGN
For newly graded areas, HSG 'A' soils
C = 0.020 x CN - 1.0
Conservative assumption
For established grass lined channel
Temporary Liner Specifications -ERONET S75
Manning's "n"Description
12 Months
Permanent Liner Specifications -ERONET P300
Matrix Netting Allowabe Partially Vegetated Allowable Partially Vegetated
Velocity (f/s)Shear Stress [lb/ft^2]
100% UV Stable
Polypropylene Fiber - 0.7lb/sy
T: UV-Stabilized Polypropylene - 5lb/1000sf
B: UV-Stabilized Polypropylene - 3lb/1000sf 9.0 8.0
100% Straw Fiber - 0.5lb/sy T(only): Lightweight photodegradable - 1.5lb/10000sf 5.0 1.55
Matrix Netting Allowabe Unvegetated Allowable Partially Vegetated
Velocity (f/s)Shear Stress [lb/ft^2]
Project Name:Wilmington CNG Station Date:2/11/2021
Project Number:PNG-20000 Calculated By:KAS
Channel Number:PD-5
I. FLOW CALCULATIONS
Drainage Area =1.59 acres
SCS CN =92
Rational C =0.84
TC =5.00 min
I2 =7.44 in/hr Calculated values are for the Raleigh-Durham area. For other areas, values will have to be input manually.
I10 =9.70 in/hr
Q2 =9.94 cfs
Q10 =12.96 cfs
II. SWALE CALCULATIONS
Proposed Channel Section
Longitudinal Slope =1.67%
Left Sideslope =4.00 H:V
Right Sideslope =4.00 H:V
Maximum Vel. =4.50 ft/s
Bottom Width =0.00 ft
10-Year Storm Calculations (for Permanent Liner)
Match Manning's "n" to Calculated "n" and adjust Depth until Capacity matches Flow (Q10).
Depth Flow Area
Wetted
Perimeter
Hydraulic
Radius Velocity VR Flow (Q10)Capacity Shear Stress
Liner Description/
Selection Calculated
[ft][ft2][ft][ft][ft/sec][ft2/sec][cfs][cfs][lb/ft^2]"n"
0.110 0.75 2.25 6.18 0.36 0.89 0.32 12.96 2.00 0.78 Tall Fescue 0.110
0.032 0.75 2.25 6.18 0.36 3.06 n/a 12.96 6.88 0.78 ERONET P300 0.032
------->NO PERMANENT LINER REQUIRED
------->VELOCITY IS OKAY
------->SHEAR STRESS IS OKAY
2-Year Storm Calculations (for Temporary Liner)
Depth Flow Area Wetted PerimeterHydraulic Rad.Velocity VR Flow (Q2)Capacity Shear Stress Calculated
[ft][ft2][ft][ft][ft/sec][ft2/sec][cfs][cfs][lb/ft^2]"n"
0.022 0.4 0.64 3.30 0.19 2.92 n/a 9.94 1.87 0.42 Bare Earth -
0.055 0.5 1.00 4.12 0.24 1.36 n/a 9.94 1.36 0.52 ERONET S75 0.055
------->CHANNEL UNSTABLE - TEMPORARY LINER REQUIRED
------->VELOCITY IS OKAY
------->SHEAR STRESS IS OKAY
Liner Longevity ->
T = Top; B = Bottom; M = Middle
T = Top; B = Bottom; M = Middle
Manning's "n"
EROSION CONTROL CHANNEL DESIGN
For newly graded areas, HSG 'A' soils
C = 0.020 x CN - 1.0
Conservative assumption
For established grass lined channel
Temporary Liner Specifications -ERONET S75
Manning's "n"Description
12 Months
Permanent Liner Specifications -ERONET P300
Matrix Netting Allowabe Partially Vegetated Allowable Partially Vegetated
Velocity (f/s)Shear Stress [lb/ft^2]
100% UV Stable
Polypropylene Fiber - 0.7lb/sy
T: UV-Stabilized Polypropylene - 5lb/1000sf
B: UV-Stabilized Polypropylene - 3lb/1000sf 9.0 8.0
100% Straw Fiber - 0.5lb/sy T(only): Lightweight photodegradable - 1.5lb/10000sf 5.0 1.55
Matrix Netting Allowabe Unvegetated Allowable Partially Vegetated
Velocity (f/s)Shear Stress [lb/ft^2]
Sedimentation and Erosion Control Report Then John R. McAdams Company Piedmont Natural Gas 2/15/2021 Wilmington CNG Station Wilmington, North Carolina
11
APPENDIX F: DEED