20210212_Response_sediment_calculations

A & H WNE
41,01 SAND COMPANY, �LIC
SEMMEN u ` ION & E6 OMN CONTROL
CALCULAMNS
RE�EI\jeD
FEB 12 V11
LAND FRo RAM
MINING
•e�sir•:;I.
Prepared By:
n
n Y � .;'r•j�ar�,'R m
ENGINEERING - SURVEYING ,?
CORPORATE LICENSE:C-17774.,,t�4°;C+,•..,.;r.''.V�a;q:n'
101 W. MAIN ST., SUITE 202
GARNER, NC 27529
PHONE[phone]
FAX[phone] FCtS�evq,e y 9, 20 Z1

A&H Mine
401 Sand Company
Doc Brown Road
Raeford, NC
Sedimentation & Erosion Control Calculations
TABLE OF CONTENTS
Drainage Area Map 1.0
Drainage Area 1 2.0
Runoff Volume
Drainage Area 2 3.0
Runoff Volume
Sedimentation Basin 1 Design
Outlet Pipe Design
Outlet Stabilization Design
Diversion Ditches to Sediment Basin 1 Design
Drainage Area 3 4.0
Runoff Volume
Sedimentation Basin 2 Design
Outlet Pipe Design
Outlet Stabilization Design
Diversion Ditch to Sediment Basin 2 Design
Drainage Area 4 5.0
Runoff Volume
Sedimentation Basin 3 Design
Outlet Pipe Design
Outlet Stabilization Design
Diversion Ditches to Sediment Basin 3 Design

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Tit-55, 25-Year Storm
401 Sand Mine
Hoke County, NC
Drainage Area 1
Runoff Volume
Q=(P-le)2/((P-la)+S)
Q= accumulated runoff(in.)
P= accumulated rainfall (potential maximum runoff) (in.)
1a intital abstraction including surface storage, interception and infiltration prior to runoff
S= potential maximum soil retention (in.)
Infiltratation for TR-55
la 0.2S
CN for TR-55
CN=1000/(10+S)
CN= Curve Number
Soil Type
CN= from Runoff Curve Numbers
P= in.
A= acres
S= 2.99 in.
Ia 0.60 in.
la/P= 0.09
Q= 3.94 in.
For Time of Concentration, Tc
T,=(0.007(nL)o.e/PZ.5So.4
T,= Time of Concentration
n= Manning's"n"
L= Flow length, ft.
P25= 25-year, 24-hour rainfall, (in.)
S= Ground slope, (ft/ft)
T 0.26 Hours

Peak Discharge
QP Q AQFP
Qp Peak Discharge(cfs)
Qu Unit Peak Discharge for Type II Rainfall (csm/in)
A= 0.034 Drainage Area, (sq. mile)
Q= 3.937 Runoff Depth (in)
FP Pond and swamp adjustment factor
QP 96.57 cfs

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TP-55, 25-Year Storm
401 Sand Mine
Hoke County, NC
Drainage Area 2
Runoff Volume
Q=(p-la)2/((p-la)+S)
Q= accumulated runoff(in.)
P= accumulated rainfall (potential maximum runoff) (in.)
la intital abstraction Including surface storage, interception and infiltration prior to runoff
S= potential maximum soil retention (in.)
Infiltratation for TR-55
]a US
CN for TR-55
CN=1000/(10+S)
CN= Curve Number
Soil Type
CN= from Runoff Curve Numbers
P= in.
A= acres
S= 2.99 in.
la 0.60 in.
la/P= 0.09
Q= 3.94 in.
For Time of Concentration,Tc
Te(0.007(nL)o.e/P2a.5So.4
T,= Time of Concentration
n= Manning's"n"
L= Flow length, ft.
P25= 25-year, 24-hour rainfall, (in.)
S= Ground slope, (fUft)
T�= 0.36 Hours

Peak Discharge
QP Q�AQFP
QP Peak Discharge (cfs)
Q.=®Unit Peak Discharge for Type II Rainfall (csm/in)
A= 0.082 Drainage Area, (sq. mile)
Q= 3.937 Runoff Depth (in)
FP Pond and swamp adjustment factor
QP 209.96 cfs

Sedimentation Basin Sizing
401 Sand Mine
Hoke County, NC
Sedimentation Basin No. 1
Drainage Area 52.509 Acres
Drainage Area Check Okay
Disturbed Area 52.509 Acres
Discharge. 306.53 ft3/s Including flow from Drainage Area 1
Minimum Volume Reqd' 94,516 ft3
Minimum Surface Area Reqd' 99,623 ft'
Length 500 ft
Min. Basin Front Width 200 ft
Min. Basin Back Width 200 it
Depth 5 it
Side Slopes 2.5 :1, fUft
Length/Width Check Okay
Okay
Bottom Length 475 ft
Bottom Front Width 175 ft
Bottom Back Width 175 ft
Top Surface Area 100,000 ftZ
Bottom Surface Area 83,125 ftZ
Total Volume 456,771 ft3
Surface Area Check Okay
Volume Check Okay
Basin Dewatering
Dewater Time 4 days
Flow 57,096 ft3/d, split between the two skimmers
Skimmer Size 8 in
Orifice Size 5.502 in
Spillway Spillway calculations are not applicable, the riser is the only discharge
Flow Reqd' 305.87 ft3/s
Spillway Width ft
Side Slope Ratio :1 ft/ft
Depth Oft, assumed depth, 0.5 it maximum
Velocity #DIV/01 ft/s, less than 2 ft/s ideal for peak flow, Q25
Capacity 0.00 ft3/s, with a weir coefficient of 3.0 for a broad-crested weir
Riser and Barrel
Number of Risers 2 each with individual outlets
Flow 153.27 cfs
Diameter 51 in, 15" min. for CMP
Driving Head 2.6'ft
Weir Capacity 177.80 cis
Capacity Check Okay
Buoyancy Check 5,460 pounds
Anchor Collar Size, Square 9 ft, square, 6 inches thick

Gravity Flow for Pipes
401 Sand Mine
Hoke County, NC
Discharge pipes from SB 1
One discharge pipe for each riser
Using Manning's Equation..
Q = (1.491n)ARv3Su2
Where...
Q = the flow in cubic feet per second (ft3ts)or cfs
n =the Manning's roughness coefficient, and n=0.013 is used per regulations
S = Slope (fVft)
R= Hydraulic radius (ft)
A= Cross sectional area of flow (ft2)
Use Appendix 16.A in Civil Engineering Reference Manual to find values for A and R
D= 54:Pipe Diameter, in inches
4.5 Pipe Diameter, in feet
So...
A= 15.91 ft2
R = 1.125ft
S = 0.006&ftfft
Q = 159 cfs
71369 gpm
For an inlet control situation only, with respect to the culvert orifice
D= 4.50 Pipe Diameter, in Feet
Cd= 0.60 Coefficient of discharge, dimensionless
A= 15.91 ft2,Cross-sectional area of flow at orifice entrance
g= 32.20 Acceleration of gravity(ft/s2)
h= 2.50 ft, Driving head, measured from the centroid of the orifice area to the water surface
Q= 768.38 cfs, Discharge

For culverts with outlet control situation (NOT APPLICABLE)
L= ft, culvert length
d.= ft,
TW= 2.25 ft, tailwater, in relation to pipe diameter
With culvert flowing full, the minimum headwater, HW is
HW= ®ft
H = -2.25 ft, Total head
g = 32.20 Acceleration of gravity(fUs2)
ka= Entrance Loss coefficient
n = 0.013 Mannings coefficient
Q = #NUMI cfs, total capacity with outlet control
To determine velocity
V=the velocity of the flow in feet per second (fUs)or fps
n =the Manning's roughness coefficient, and n=0.013 is used per regulations
S = Slope(fUft)
R = Hydraulic radius (ft)
So...
S = 0.0065 fUft
R= 1.125ft
V= 10.00 ft/s
To determine velocity, flowing at Q25
Q25= 153.27 ft'/s, from discharge calculations per riser
0 = 2(cos1(1-(y/(D/2))
Q =(1.49/n)(DZ/8(0-sin0)(D(0-sin0)/40)2J'
y= depth of flow in pipe, It
0 =the angle of the edges of the surface across the pipe, radians
n = Mannings coefficient, typically 0.013
y= ft
n=
0= 4.37 radians
Q26= 153.27 f?/s, as calculated for pipe flow

Cross-sectional Area of the flow
A=((D2/8)(6-sin0))
R=(D2(e-sin0)/(D8/2))
A=cross-sectional area of the flow at the depth of flow, ft2
R= hydraulic radius of the flow in the pipe, ft
A25= 13.46 fe
5 = 0.0065 ft/ft
R25= 1.37 ft
V25= 11.39 ft/s

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S6d1mentation & Erosion Control Calculations
Diversion Swale Calculations
401 Sand Mine
Hoke County, NC
Diversion Ditch 1-1
Slope of Ditch = H/L
H =The difference in elevation along the ditch, in feet
Where: L=The length of the ditch, in feet
So therefore...
H = MM ft
If... L= it
Slope= 0,02
Solving for depth
Ditch Bottom Width 201ft
Ditch Side Slope 24.1 ratio, H:V
Manning's"n" 0.018,
Depth 0.75 ft
Discharge 76.63 cfs
Area 16.23 fe
Wp 23.37 it
H. Radius 0,69 ft
z,aq 6.36
z,vg 12.72
Velocity 4.72 ft/s
If velocity of flow is greater than 2 ft/s, matting is required
Shear Stress: T=yds
T= Shear stress in pounds/ft2(psf)
Where y= unit weight of water, 62.4 Ib/fP (pcf)
d =flow depth in ft
s= slope of ditch, ft/ft
d = 0.75
Therefore, if: S = 0.02
T= 1,00 psf
Use curled wood matting

S2dimentation & Erosion Control Calculations
Diversion Swale Calculations
401 Sand Mine
Hoke County, NC
Diversion Ditch 1-2
Slope of Ditch = H/L
H =The difference in elevation along the ditch, in feet
Where: L= The length of the ditch, in feet
So therefore...
H = ft
If... L= ft
Slope = 0.03
Solving for depth
Ditch Bottom Width ft
Ditch Side Slope :1 ratio, H:V
Manning's"n"
Depth ft
Discharge 38.32 cfs
Area 9.23 ft2
WP 21.98 ft
H. Radius 0.42 ft
zMCI 2.59
zavy 5.18
Velocity 4.15 ft/s
If velocity of flow is greater than 2 ft/s, matting is required
Shear Stress: T=yds
T= Shear stress in pounds/ft2 (psf)
Where y= unit weight of water, 62.4 Ib/fO (pcf)
d= flow depth in ft
s= slope of ditch, ft/ft
d = 0.44
Therefore, if: s= 0.03
T= 0.88 psf
Use curled wood matting

Sedimentation & Erosion Control Calculations
Diversion Swale Calculations
401 Sand Mine
Hoke County, NC
Diversion Ditch 1-3
Slope of Ditch = H/L
H =The difference in elevation along the ditch, in feet
Where: L=The length of the ditch, in feet
So therefore...
H = it
If... L= ft
Slope= 0.03
Solving for depth
Ditch Bottom Width 20 ft
Ditch Side Slope 2 :1 ratio, H:V
Manning's"n" 0.018
Depth 0.46 ft
Discharge 38.32 cfs
Area 9.62 fe
WP 22.06 ft
H. Radius 0.44 ft
zreq 2.77
zeva 5.53
Velocity 3.98 ft/s
If velocity of flow is greater than 2 ft/s, matting is required
Shear Stress: T=yds
T=Shear stress in pounds/ft? (psf)
Where y=unit weight of water, 62.4 Ib/ft3(pcf)
d =flow depth in ft
s=slope of ditch, fl/ft
d = 0.46
Therefore, if: S= 0.03
T= 0.80 psf
Use curled wood matting

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TES-55, 25-Year Storm
401 Sand Mine
Hoke County, NC
Drainage Area 3
Runoff Volume
Q=(P-la)Z/((P-la){S)
Q= accumulated runoff(in.)
P= accumulated rainfall (potential maximum runoff) (in.)
la intital abstraction including surface storage, interception and infiltration prior to runoff
S= potential maximum soil retention (in.)
Infiltratation for TR-55
la 0.2S
CN for TR-55
CN=1000/(10+S)
CN= Curve Number
Soil Type
CN= from Runoff Curve Numbers
P= in.
A= acres
S= 2.99 in.
la 0.60 in.
IjP= 0.09
Q= 3.94 In.
For Time of Concentration, Tc
T,=(0.007(nL)o.e/P2.5Sa.4
T,= Time of Concentration
n= Manning's"n"
L= Flow length, ft.
P25= 25-year, 24-hour rainfall, (in.)
S==Ground slope, (ft/ft)
T 0.31 Hours

Peak Discharge
QPQ�AQFP
1
QP Peak Discharge (cfs)
Qu=' 675 Unit Peak Discharge for Type II Rainfall (csm/in)
A= 0.041 Drainage Area, (sq. mile)
Q= 3 937 Runoff Depth (in)
FPi 1.00 Pond and swamp adjustment factor
QP 108.96 cfs

Sedimentation Basin Sizing
401 Sand Mine
Hoke County, NC
Sedimentation Basin No. 2
Drainage Area 26.838 Acres
Drainage Area Check Okay
Disturbed Area 26.838 Acres
Discharge 108.96 ft3/s
Minimum Volume Reqd' 48,308 fe
Minimum Surface Area Reqd' 35,411 ft2
Length ft
Min. Basin Front Width ft
Min. Basin Back Width0:1, fuft
ft
Depth ft
Side Slopes
Length/Width Check Okay
Okay
Bottom Length 340 ft
Bottom Front Width 100 ft
Bottom Back Width 60 ft
Top Surface Area 36,000 ft2
Bottom Surface Area 27,200 ft2
Total Volume 125,890 ft'
Surface Area Check Okay
Volume Check Okay
Basin Dewatering
Dewater Time ®days
Flow 31,473 ft3/d
Skimmer Size ®in
Orifice Size 4.085 in
Spillway
Flow Reqd' 108.59 fe/s
Spillway Width ft
Side Slope Ratio :1 Wit
Depth Oft, assumed depth, 0.5 ft maximum
Velocity 1.95 ft/s, less than 2 ft/s ideal for peak flow, Q25
Capacity 116,67 ft3/s,with a weir coefficient of 3.0 for a broad-crested weir
Riser and Barrel
Flow 108.96 cis
Diameter in, 15" min. for CMP
Driving Head ft, to bottom elevation of spillway
Weir Capacity 119.96 cfs
Capacity Check Okay
Buoyancy Check 4368 pounds
Anchor Collar Size,Square 8 ft, square, 6 inches thick

Gravity Flow for Pipes
401 Sand Mine
Hoke County, NC
Discharge pipe from SB 2
Using Manning's Equation..
Q = (1.49/n)ARy3S'n
Where...
Q =the flow in cubic feet per second (ft3/s)or cis
n =the Manning's roughness coefficient, and n=0.013 is used per regulations
S =Slope(ft/ft)
R = Hydraulic radius (ft)
A= Cross sectional area of flow(ftZ)
Use Appendix 16.A in Civil Engineering Reference Manual to find values for A and R
D= r+ " Pipe Diameter, in inches
4.5 Pipe Diameter, in feet
So...
A= 15.91 ft'
R= 1.125 ft
S = 0.005 ft/ft
Q = 139 cfs
62595 gpm
For an inlet control situation only,with respect to the culvert orifice
D= 4.50 Pipe Diameter, in Feet
Cd= 0.60 Coefficient of discharge, dimensionless
A= 15.91 ft2,Cross-sectional area of flow at orifice entrance
g= 32.20 Acceleration of gravity(ft/S2)
h= 2.50 ft, Driving head, measured from the centroid of the orifice area to the water surface
Q= 768.38 cfs, Discharge

For culverts with outlet control situation (NOT APPLICABLE)
L= it, culvert length
d.= mit,
TW= 2.25 it, tailwater, in relation to pipe diameter
With culvert flowing full, the minimum headwater, HW is
HW= ft
H = -2.25 ft,Total head
g = 32.20 Acceleration of gravity (fVs2)
ke= ®Entrance Loss coefficient
n = 0.013 Mannings coefficient
Q = #NUMI cis, total capacity with outlet control
To determine velocity
V=the velocity of the flow in feet per second (ft/s)or fps
n = the Manning's roughness coefficient, and n=0.013 is used per regulations
S = Slope (ft/ft)
R= Hydraulic radius (ft)
So...
S = 0.005 ft/ft
R = 1.125 it
V= 8.77 ft/s
To determine velocity, flowing at Q25
Q25= 108.96 Os, from discharge calculations
0 = 2(cos 1(1-(y/(D/2))
Q=(1.49/n)(D2/8(0-sin0)(D(0-sine)/40)213
y=depth of flow in pipe, it
0=the angle of the edges of the surface across the pipe, radians
n = Mannings coefficient, typically 0.013
y= ft
n=
0= 3.82 radians
Q25= 108.96 ft3/s, as calculated for pipe flow

s
Cross-sectional Area of the flow
A=((D2/8)(0-sin0))
R=(D2(0-sing)/(DO/2))
A=cross-sectional area of the flow at the depth of flow, ft2
R= hydraulic radius of the flow in the pipe,ft
A25= 11.24 W
S= 0.005 ft/ft
Res= 1.31 ft
V25= 9.70 ft/s

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Sedimentation & Erosion Control Calculations
Diversion Swale Calculations
401 Sand Mine
Hoke County, NC
Diversion Ditch to Basin 2
Slope of Ditch= H/L
Where: H =The difference in elevation along the ditch, in feet
L=The length of the ditch, in feet
So therefore...
If... H = V�Ift
L= ft
Slope= 0.01
Solving for depth
Ditch Bottom Width ft
Ditch Side Slope :1 ratio, H:V
Manning's"n"
Depth ft
Discharge 108.96 cfs
Area 17.95 ft2
W p 23.71 ft
H. Radius 0.76 ft
z,aq 14.91
ze 9 14.91
Velocity 6.07 ft/s
If velocity of flow is greater than 2 ft/s, matting is required
Shear Stress: T=yds
Where T= Shear stress in pounds/fe(psf)
y= unit weight of water, 62.4 lb/ft? (pcf)
d =flow depth in ft
s= slope of ditch, ft/ft
Therefore, if: d = 0.83
s= 0.01
T= 0.40 psf
Use curled wood matting

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TR-55, 25-Year Storm
401 Sand Mine
Hoke County, NC
Drainage Area 4
Runoff Volume
Q=(P-la)2/((P-le)+S)
Q= accumulated runoff(in.)
P= accumulated rainfall (potential maximum runoff) (in.)
la intital abstraction including surface storage, interception and infiltration prior to runoff
S= potential maximum soil retention (in.)
Infiltratation for TR-55
la 0.2S
CN for TR-55
CN=1000/(10+S)
CN= Curve Number
Soil Type
CN= from Runoff Curve Numbers
P= in.
A= acres
S= 2.99 in.
le 0.60 in.
IeIP= 0.09
Q= 3.94 In.
For Time of Concentration,Tc
Tc=(0.007(nQ0.8/Pz.6SOA
T,= Time of Concentration
n= Manning's"n"
L= Flow length, ft.
P26= 25-year, 24-hour rainfall, (in.)
S= Ground slope, (ft/ft)
T,= 0.28 Hours

Peak Discharge
QP Q�AQFP
QP Peak Discharge (cfs)
Q.=®Unit Peak Discharge for Type II Rainfall (csmlin)
A= 0.024 Drainage Area, (sq. mile)
Q= 3.937 Runoff Depth (in)
FP Pond and swamp adjustment factor
QP 66.70 cfs

Sedimentation Basin Sizing
401 Sand Mine
Hoke County, NC
Sedimentation Basin No. 3
Drainage Area 15.49 Acres
Drainage Area Check Okay
Disturbed Area 15.49 Acres
Discharge 66.70 ft3/s
Minimum Volume Reqd' 27,882 ft'
Minimum Surface Area Reqd' 21,678 f?
Length ft
Min. Basin Front Width ft
Min. Basin Back Width0:1,
ft
Depth ft
Side Slopes ft/ft
Length/Width Check Okay
Okay
Bottom Length 200 ft
Bottom Front Width 80 ft
Bottom Back Width 80 ft
Top Surface Area 22,000 ft?
Bottom Surface Area 16,000 f?
Total Volume 75,467 ft3
Surface Area Check Okay
Volume Check Okay
Basin Dewatering
Dewater Time ®days
Flow 18,867 fP/d
Skimmer Size in
Orifice Size 3.163 in
Spillway
Flow Reqd' 66.48 ft3ls
Spillway Width ft
Side Slope Ratio :1 ft/ft
Depth ft, assumed depth, 0.5 ft maximum
Velocity 1.86 ft/s, less than 2 ft/s ideal for peak flow, Q2s
Capacity 74.25 ft3/s,with a weir coefficient of 3.0 for a broad-crested weir
Riser and Barrel
Flow 66.70 cfs
Diameter in, 15" min. for CMP
Driving Head ft, to bottom elevation of spillway
Weir Capacity 69.26 cis
Capacity Check Okay
Buoyancy Check 3451 pounds
Anchor Collar Size, Square 7 ft, square, 6 inches thick

Gravity Flow for Pipes
401 Sand Mine
Hoke County, NC
Discharge pipe from SB 3
Using Manning's Equation..
Q = (1.49/n)AR13S11
Where...
Q=the flow in cubic feet per second (ft3/s) or cfs
n =the Manning's roughness coefficient, and n=0.013 is used per regulations
S = Slope(ft/ft)
R= Hydraulic radius (ft)
A= Cross sectional area of flow (ft?)
Use Appendix 16.A in Civil Engineering Reference Manual to find values for A and R
D= 42 Pipe Diameter, in inches
3.5 Pipe Diameter, in feet
So...
A= 9.62 ftZ
R = 0.875 ft
S = 0.005 ft/ft
Q = 71 cfs
32025 gpm
For an inlet control situation only, with respect to the culvert orifice
D= 3.50 Pipe Diameter, in Feet
Cd= 0.60 Coefficient of discharge, dimensionless
A= 9.62 f?,Cross-sectional area of flow at orifice entrance
g= 32.20 Acceleration of gravity (ft/sZ)
h= ft, Driving head, measured from the centroid of the orifice area to the water surface
Q= 371.86 cfs, Discharge

For culverts with outlet control situation (NOT APPLICABLE)
L= ft, culvert length
dc= mit,
TW= 1.75 ft, tailwater, in relation to pipe diameter
With culvert flowing full, the minimum headwater, HW is
HW = ft
H = -1.75 ft,Total head
g = 32.20 Acceleration of gravity(ft/sZ)
ke= Entrance Loss coefficient
n = 0.013 Mannings coefficient
Q= #NUM! cfs, total capacity with outlet control
To determine velocity
V = the velocity of the flow in feet per second (ft/s) or fps
n = the Manning's roughness coefficient, and n=0.013 is used per regulations
S = Slope (ft/ft)
R = Hydraulic radius (ft)
So...
S = 0.005 ft/ft
R = 0.875 ft
V= 7.41 ft/s
To determine velocity,flowing at Q25
Q25= 66.70 ft'/s, from discharge calculations
0 =2(cos 1(1-(y/(D/2))
Q=(1.49/n)(D2/8(0-sin0)(D(0-sin0)/40)2/3
y= depth of flow in pipe, ft
0 =the angle of the edges of the surface across the pipe, radians
n = Mannings coefficient, typically 0.013
y= ft
n=
0= 4.27 radians
Q25= 66.70 ft3/s, as calculated for pipe flow

l ;
Cross-sectional Area of the flow
A=((D218)(0-sin6))
R=(D2(0-sin0)1(D012))
A=cross-sectional area of the flow at the depth of flow,ft2
R =hydraulic radius of the flow in the pipe,ft
A25= 7.92 ft2
S = 0.005 ftlft
R25= 1.06 ft
V25= 8.43 ft/s

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Sedimentation & Erosion Control Calculations
Diversion Swale Calculations
401 Sand Mine
Hoke County, NC
Diversion Ditch 3-1
Slope of Ditch= H/L
Where: H =The difference in elevation along the ditch, in feet
L=The length of the ditch, in feet
So therefore...
If... H = ft
L= ft
Slope= 0.023
Solving for depth
Ditch Bottom Width ft
Ditch Side Slope :1 ratio, H:V
Manning's"n"
Depth ft
Discharge 33.35 cfs
Area 6.11 ft2
WP 21.33 ft
H. Radius 0.29 ft
zfeq 2.65
zeV9 2.65
Velocity 5.46 ft/s
If velocity of flow is greater than 2 ft/s, matting is required
Shear Stress: T=yds
Where T= Shear stress in pounds/ft2 (psf)
y= unit weight of water, 62.4 IWO (pcf)
d = flow depth in ft
s= slope of ditch, ft/ft
Therefore, if: d = 0.30
s= 0.02
T= 0.43 psf
Use curled wood matting

Sedimentation & Erosion Control Calculations
Diversion Swale Calculations
401 Sand Mine
Hoke County, NC
Diversion Ditch 3-2
Slope of Ditch = H/L
Where: H =The difference in elevation along the ditch, in feet
L= The length of the ditch, in feet
So therefore...
If... H = - ft
L= 320'ft
Slope= 0.013
Solving for depth
Ditch Bottom Width 101ft
Ditch Side Slope 2 :1 ratio, H:V
Manning's"n" 0,018
Depth 0,53 ft
Discharge 33.35 cfs
Area 5.90 ft2
Wp 12.38 ft
H. Radius 0.48 It
z,ay 3.60
Zavg 3.60
Velocity 5.65 ft/s
If velocity of flow is greater than 2 ft/s, matting is required
Shear Stress: T=yds
Where T= Shear stress in pounds/ft?(psf)
y= unit weight of water, 62.4 Iblft3 (pcf)
d =flow depth in ft
s=slope of ditch, ft/ft
Therefore, if: d = 0.53
s = 0.01
T= 0.42 psf
Use curled wood matting