SW6231102_Stormwater Report_20231102

STORMWATER MANAGEMENT REPORT
for
BUFFALO CREEK SUBDIVISION
Submittal to:
NCDEQ STORMWATER PROGRAM
Prepared for:
GRACELAND DEVELOPMENT, INC.
P.O.BOX 531
PARKTON, NC 28371
CONTACT: JOEY PEINFIELD
PHONE: [phone]
Submittal Date:
September 2022
Prepared by: -�N CARE)'',,,
_Nov...........
Ess%;1!'�y
HILL/AR _ _ _ 135lII
ENGINEERING, PLL C :. o
3417 Winterwind Circle,Sanford,NC 27330 '',9'p:QCIN�: ••P�:`
PO Box 249,Sanford,NC 27331 •••Phone:[phone] 'of,
•E. H\\-
e-mail:[e-mail]
NC License#:P-0836
9/5/23
RAFTING AND DESIGN
SERVICES,INC.
6728 Carbonton Road
Sanford, NC 27330
[phone]
[e-mail]
DDS Project#2023-07

TABLE OF
CONTENTS
SECTION PAGE
I. EXISTING CONDITIONS
A. PROPERTY 1
B. WATERSHED 2
C. JURISDICTIONAL WATERS 2
D. FEMA FLOOPLAIN... 2
E. SOILS 2
II. AGENCY STORMWATER REQUIREMENTS
A. HOKE COUNTY .2
B. NCDEQ 3
III. PROPOSED IMPROVEMENTS
A. PROJECT DESCRIPTION 3
B. LAND DISTURBANCE AND EROSION CONTROL 3
C. IMPERVIOUS SURFACE 3
D. DRAINAGE AND STORMWATER MANAGEMENT... 4
APPENDICES
A. Computations
Minor System
Grass Conveyance Swales
Erosion Control
B. Maps
Inlet Drainage Area
Erosion Control Drainage Area
C. Soil Survey Map
D. FEMA FIRM Map
E. USGS MAP
F. STORMWATER FORMS
SUPPLEMENT-EZ
OPERATION & MAINTENANCE AGREEMENT
BMP SUPPLEMENT FORMS

EXISTING CONDITIONS
A. PROPERTY
The proposed project site is on one 52.2 AC parcel (PIN# 5849-40-00-
1096) in Hoke County. The property is currently undeveloped farm land
with no impervious surfaces.
The following is a summary of the adjacent properties:
To the north, undeveloped (zoning R-20)
To the south, undeveloped (zoning R-20)
To the west, undeveloped (zoning R-20)
To the east, single family and undeveloped (zoning R-20)
See Figure 1 below for an aerial view of the property for the proposed Buffalo
Creek Subdivision project (Site).
Figure 1:Aerial view of pre-developed site
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Storm water Impact Analysis
Page 1 14

B. WATERSHED
The site is located in the Gully Branch Watershed and Lumber River Basin.
The NCDEQ Stream Index for Buffalo Creek is 14-2.5 and Stream
Classification for Buffalo Creek is 'C'.
C. JURISDICTIONAL WATERS
There are no jurisdictional streams located on the site. There are no
impacts proposed with this project to jurisdictional streams or
wetlands.
D. FEMA FLOODPLAIN
There are FEMA mapped floodplains located on the site per FIRM Panel
37108488400L, effective date July 7, 2007. See Appendix D for FEMA
FIRM maps.
E. SOILS
Refer to Appendix C for the NRCS map showing anticipated on-site soils.
II. AGENCY STORMWATER REQUIREMENTS
A. Hoke County
Section 3.7 'Storm Drainage Not in Public Streets" of the Hoke County
Subdivision Ordinance details the requirements for managing
stormwater from new construction sites.
Section 3.3 'Streets" of the Hoke County Subdivision Ordinance details
the requirements for managing stormwater from new construction sites
per NCDOT requirements.
Storm water Impact Analysis
Page 2 1 4

B. NCDEQ
Hoke County is a `tipped' county and new projects located within the
county must meet NCDEQ Post Construction Stormwater Phase 2
regulations. Site requirements for stormwater control are different if the
proposed development is 'high density' (greater than 24% impervious) or
`low density' (less than 24% impervious).
III. PROPOSED IMPROVEMENTS
A. PROJECT DESCRIPTION
The proposed project will create fourty-Seven (47) single family lots (min
20,000 sf). The proposed project will add additional roads the Hoke County
road system. The design follows the Preliminary Plat that was recently
approved by Hoke County. As part of this project, public water will be
extended to serve the new lots.
B. LAND DISTURBANCE AND EROSION CONTROL
The proposed disturbed area for the proposed project is 36.0 AC +/-. A
NCDEQ Land Disturbance (Erosion Control) Permit will be obtained prior to
beginning work.
C. IMPERVIOUS SURFACE
The proposed total amount of impervious surfaces for this project is 7.41 AC.
This includes pavement and curb & gutters in the public R/W and driveways
and rooftops on each lot. The resulting percent impervious (or built-upon)
of 14.2% of the total property area. A maximum amount of 3,500 SF of
impervious area is allocated to each lot. Thus, this development is classified
as low density' under NCDEQ Phase II regulations.
Storm water Impact Analysis
Page 3 14

D. DRAINAGE AND STORMWATER MANAGEMENT
i. Roadway Drainage -Major System
The proposed roadway will have curb and gutter. Catch basins in
the gutter line will provide the roadway drainage. Catch basins
were spaced based on gutter spread not exceeding one-half lane
width during a 4 in/hr storm (NCDOT guidelines). The minor pipe
system is sized based on 10-year storm flow and cross-pipes are
sized based on 25-year storm flow not exceeding the hydraulic
capacity of each pipe segment (as open channel flow, that is, non-
pressure flow).
ii. Grass Conveyance Swales/Dispersed Flow
As stated in Section III. C. above, proposed impervious is less than 24%
and, therefore is classified as `Low Density' per NCDEQ regulations.
Per NCDEQ guidance, Grass swales/dispersed flow are proposed to
receive runoff collected by the catch basins in the road system to help
treat the runoff before being discharged to the jurisdictional waters.
These swales/dispersed flow areas have a longitudinal slope of 0.0% to
1.0% that discharge into an existing drainage swale to the south. There
are Three (3) proposed grass outlets, each with a length greater than
100 LF.
iii. Methodology and computations
Refer to Appendix A for storm drainage and stormwater
management computations. Hydrologic computations were based
on the Rational Method for storm drainage and SCS method for
stormwater management. Rainfall intensity was determined based
on data of the closest rainfall gauge listed on the NOAA website.
Drainage areas were delineated based on a combination of field
and LIDAR topography.

Stormwater Impact Analysis
Page 4 14
APPENDIX A
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BUFFALO CREEK SUBDIVISION
DRAINAGE/GUTTER SPEAD CALCULATIONS
Upstream Inlet Pipe Capacity Gutter Gutter Gutter
Drainage Area Inlet Rainfall Pipe Diameter Total Pipe Flow Total System Pipe Slope Pipe Invert Pipe Invert Elevation(Top) Inlet Elevation Flow(Total Flow(Total Gutter Spread
Inlet ID Inlet ID Runoff Notes
(acres) Intensity'(in/h) (in) Pipe Material Pipe Length(ft) (Full Flow) (ft'/s)(1) Flow(tt/s) (ft/ft) (Upstream)(ft) (Downstream)(ft) Inlet ID (ft)(3) (Invert)(ft) Inlet Type 1=4 in/hr Intercepted) Bypassed) (ft)(4)(6)
Coefficient (ft'/s) (f/s)(2)
(ft/s) (ft'/s)
CB 114 CB 113 0.35 0.47 7.98 15 Class III RCP 27.00 5.04 1.31 1.31 0.0052 299.57 299.43 CB 114 302.57 299.57 NCDOT 840.17 0.66 0.50 0.16 4.75
CB 113 CB 106 0.35 0.75 7.98 15 Class III RCP 27.00 5.04 2.09 2.09 0.0052 299.57 299.43 CB 113 302.57 299.57 NCDOT 840.17 1.21 0.78 0.39 6.25 0.5"Depression
CB 112 CB 111 0.35 1.14 7.98 15 Class III RCP 27.00 5.04 3.18 3.18 0.0052 299.57 299.43 CB 112 302.57 299.57 NCDOT 840.17 1.60 0.97 0.63 6.25
CB 111 CB 110 0.35 1.09 7.98 15 Class III RCP 328.00 6.25 3.04 6.23 0.0086 299.43 296.62 CB 111 302.58 299.43 NCDOT 840.03 1.53 0.93 0.60 6.10
CB 110 CB 109 0.35 0.45 7.98 15 Class III RCP 328.00 6.25 1.26 7.49 0.0086 299.43 296.62 CB 110 302.58 299.43 NCDOT 840.03 1.23 0.80 0.43 5.50
CB 109 CB 108 0.35 0.15 7.98 18 Class III RCP 27.00 8.04 0.42 7.90 0.0052 296.37 296.23 CB 109 300.37 296.37 YARD INLET 0.64 0.49 0.15 3.85
CB 108 DI 107 0.35 0.66 7.98 24 Class III RCP 153.00 17.32 1.84 9.75 0.0050 296.23 295.47 CB 108 300.37 296.23 NCDOT 840.03 1.55 0.94 0.61 6.15
DI 107 CB 106 0.35 0.29 7.98 24 Class III RCP 38.00 17.32 0.81 10.56 0.0055 294.97 294.76 DI 107 299.00 294.97 NCDOT 840.03 0.41 - - -
CB 106 CB105 0.35 0.78 7.98 24 Class III RCP 27.00 17.32 2.18 14.83 0.0052 294.76 294.62 CB 106 299.04 294.76 NCDOT 840.03 2.09 2.09 - 4.92
CB 105 FES 104 0.35 0.41 7.98 24 Class III RCP 45.00 17.32 1.15 15.98 0.0051 294.62 294.39 CB 105 299.04 294.62 NCDOT 840.17 0.57 0.57 - 1.50
FES 103(5) CB 102 0.35 18.09 8.89 36 Class III RCP 28.00 68.54 56.29 56.29 0.0089 276.00 275.75 FES 103(5) 300.37 276.00 NCDOT 840.03 - - - -
CB 102 CB 101 0.35 0.23 7.98 36 Class III RCP 27.00 69.67 0.64 56.93 0.0093 275.75 275.50 CB 102 299.00 275.75 NCDOT 840.03 0.32 0.28 0.04 2.20
CB 101 FES 100 0.35 0.14 7.98 36 Class III RCP 129.00 71.16 0.39 57.32 0.0097 275.50 274.25 CB 101 299.04 275.50 NCDOT 840.03 0.20 0.19 0.01 1.45
CB 207 CB 206 0.35 1.31 7.98 15 Class III RCP 27.00 4.94 3.66 3.66 0.0052 292.95 292.81 CB 207 285.96 292.95 NCDOT 840.03 2.18 1.31 0.87 4.90
CB 206 CB 205 0.35 1.23 7.98 15 Class Ill RCP 121.00 14.84 3.44 7.09 0.0455 281.78 276.28 CB 206 285.96 281.78 NCDOT 840.17 2.06 1.26 0.80 4.75
CB 205 CB 204 0.35 0.28 7.98 15 Class III RCP 84.00 7.97 0.78 7.88 0.0129 276.28 275.20 CB 205 208.15 276.28 NCDOT 840.03 1.19 0.86 0.33 3.50
CB 204 CB 203 0.35 0.73 7.98 18 Class III RCP 27.00 5.72 2.04 2.04 0.0067 275.38 275.20 CB 204 278.38 275.38 NCDOT 840.03 1.89 1.89 - 5.00
CB 203 CB 202 0.35 0.15 7.98 18 Class III RCP 47.00 17.30 0.42 10.33 0.0049 274.74 274.51 CB 203 278.38 274.74 NCDOT 840.03 0.54 0.54 - 1.00
CB 202 CB 201 0.90 0.01 7.98 24 Class III RCP 27.00 17.30 0.07 10.41 0.0052 274.51 274.37 CB 202 278.38 274.51 NCDOT 840.03 0.08 0.08 - 0.20 Bypass discharge out C&G-EP
CB 201 FES 200 0.80 0.13 7.98 24 Class III RCP 118.00 17.30 0.83 11.24 0.0050 274.37 273.78 CB 201 278.38 274.37 NCDOT 840.03(DOUBLE) 0.43 0.36 0.07 2.70 Bypass discharge out C&G-EP
CB 303 CB 302 0.35 0.92 7.98 15 Class III RCP 27.00 4.94 2.57 2.57 0.0052 291.58 291.44 CB 303 283.72 291.58 NCDOT 840.03 1.69 1.69 - 6.00
CB 302 CB 301 0.35 0.80 7.98 15 Class III RCP 181.00 8.13 2.23 4.80 0.0615 291.44 280.30 CB 302 283.72 291.44 NCDOT 840.03 1.54 1.54 - 5.00
CB 301 FES 300 0.35 0.03 7.98 15 Class III RCP 181.00 8.13 0.08 4.89 0.0238 280.30 276.00 CB 301 283.33 280.30 NCDOT 840.03 0.04 0.04 - 0.00
CB 402 CB 401 0.35 0.77 7.98 15 Class III RCP 27.00 4.94 2.15 2.15 0.0052 291.58 291.44 CB 402 294.58 291.58 NCDOT 840.03 1.30 0.90 0.40 3.85
CB 401 FES 400 0.35 0.77 7.98 15 Class III RCP 181.00 7.97 2.15 4.30 0.0135 291.44 289.00 CB 401 294.58 291.44 NCDOT 840.03 1.33 0.91 0.42 3.90
CB 504 CB 503 0.35 0.60 7.98 15 Class Ill RCP 27.00 4.94 1.68 1.68 0.0052 295.70 295.56 CB 504 298.70 295.70 NCDOT 840.03 0.84 0.60 0.24 5.10
CB 503 CB 502 0.35 0.70 7.98 15 Class III RCP 171.00 4.94 1.96 1.96 0.0060 295.56 294.53 CB 503 298.70 295.56 NCDOT 840.03 0.98 0.68 0.30 5.55
CB 502 CB 501 0.35 0.39 7.98 15 Class III RCP 27.00 4.94 1.09 1.09 0.0052 294.67 294.53 CB 502 294.58 294.67 NCDOT 840.03 0.79 0.57 0.22 4.95
CB 501 FES 500 0.35 0.40 7.98 15 Class III RCP 183.00 8.85 1.12 2.21 0.0166 294.53 291.50 CB 501 294.58 294.53 NCDOT 840.03 0.86 0.61 0.25 5.20
CB 604 CB 603 0.35 0.70 7.98 15 Class III RCP 27.00 5.04 1.96 1.96 0.0052 295.01 294.87 CB 604 298.01 295.01 NCDOT 840.03 0.98 0.68 0.30 5.50
CB 603 CB 602 0.35 0.61 7.98 15 Class Ill RCP 220.00 5.55 1.70 3.66 0.0063 294.87 293.48 CB 603 298.01 294.87 NCDOT 840.17 0.85 0.60 0.25 5.10
CB 602 CB 601 0.35 0.53 7.98 15 Class III RCP 27.00 5.85 1.48 5.14 0.0144 293.62 293.23 CB 602 296.62 293.62 NCDOT 840.03 1.04 0.70 0.34 5.65
CB 601 FES 600 0.35 0.58 7.98 18 Class III RCP 179.00 8.04 1.62 6.76 0.0059 293.23 292.17 CB 601 296.62 293.23 NCDOT 840.03 1.06 0.71 0.35 5.70
Notes
1 Storm System Sizing based on 10-yr Storm
2 Gutter Spread Calculations based on Storm Intensity of 4 in/hr
3 CB(Catch Basin)Top Elevation is Grate at EOP
4 Gutter Spread Width is measured from Edge of Pavement
5 Storm System Sizing based on 25-yr Storm-For cross-pipe
6 Allowable Gutter Spread is 6.25 ft based on 12.5 Travel Lane

Culvert Report
Hydraflow Express Extension for AutoCAD®Civil 3D®2009 byAutodesk, Inc. Wednesday,Aug 23 2023
CULVERT #1
Invert Elev Dn (ft) = 307.10 Calculations
Pipe Length (ft) = 64.00 Qmin (cfs) = 5.49
Slope (%) = 0.50 Qmax (cfs) = 5.49
Invert Elev Up (ft) = 307.42 Tailwater Elev (ft) = Normal
Rise (in) = 18.0
Shape = Cir Highlighted
Span (in) = 18.0 Qtotal (cfs) = 5.49
No. Barrels = 1 Qpipe (cfs) = 5.49
n-Value = 0.012 Qovertop (cfs) = 0.00
Inlet Edge = Projecting Veloc Dn (ft/s) = 4.90
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.5 Veloc Up (ft/s) = 4.90
HGL Dn (ft) = 308.01
Embankment HGL Up (ft) = 308.33
Top Elevation (ft) = 310.00 Hw Elev (ft) = 308.75
Top Width (ft) = 30.00 Hw/D (ft) = 0.88
Crest Width (ft) = 10.00 Flow Regime = Inlet Control
Flow C=0.6
1=8.89
Q=CIA A=1.03
Q=5.49
Elev(It) CULVERT 11 Hw Depth(It)
311.00 ass
310.00 2.58
309.00 1.58
-Irlet conhol
308.00 0.58
307.00 .0.42
306.00 -1.42
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85
Ci Culvert HGL Embark
Reach 811

Permanent Diversion# 1A =>DA# 600A
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.30
1= 5.37 in/hr TC CALC
Q25= 15.59 A= 9.68 ac
Channel Slope= 0.50
Channel Depth= 1.50
Channel Bottom W= 0
Side Slopes= 3.00
Velocity= 3.30
Soil Type @ sandy loarr Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.41bs
dwater= 1.25 ft
T= 0.39 lbs/ft2 s= 0.005 ft/ft
Temporary= NAG S150BN
Permanent= Bermudagrass
Temporary Diversion# 1B =>DA# 600B
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.40
1= 5.37 in/hr TC CALC
Q25= 45.11 A= 21.00 ac
Channel Slope= 0.50
Channel Depth= 1.50
Channel Bottom W= 2
Side Slopes= 3.00
Velocity= 5.59
Soil Type @ sandy loarr Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 1.34 ft
T= 0.41808 lbs/ft2 s= 0.005 ft/ft
Temporary= NAG S150BN
Permanent= Bermudagrass

Permanent Diversion# 2 =>DA# 103
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.30
1= 8.89 in/hr TC CALC
Q25= 48.27 A= 18.10 ac
Channel Slope= 1.00
Channel Depth= 5.00
Channel Bottom W= 0
Side Slopes= 3.00
Velocity= 5.30
Soil Type @ sandy loarr Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater 1.2 ft
T= 0.7488 lbs/ft2 5= 0.01 ft/ft
Temporary= NAG S150BN
Permanent= Bermudagrass

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Permanent Channel# 100 =>DA# 103
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.35
1= 8.89 in/hr
Q25= 57.25 A= 18.40 ac
Channel Slope= 1.00
Channel Depth= 2.00
Channel Bottom W= 0
Side Slopes= 4.00
Velocity= 5.58
Soil Type @ sandy loarr Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 1.27 ft
T= 0.79248 lbs/ft2 5= 0.01 ft/ft
Temporary= NAG S150BN
Permanent= Bermudagrass

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Skimmer Basin# 1
Calculate Flow- Rational Method
10-Yr Storm 25-Yr Storm
010= CIA C= 0.4 Q25=CIA C= 0.4
1= 7.72 1= 8.47
Clio= 20.9984 A= 6.8 Q25 = 23.0384 A= 6.8
Calculate Required Surface Area
SA=Q10 x 325 sf/cfs Q10= 20.9984 cfs
SA= 6824.48
Side Slopes= 3 :1
Pond Depth= 2 ft
Basin Dims
Top= 71 x 142 = 10082 sf
Weir= 59 x 118 = 6962 sf
Bottom = 47 x 94 = 4418 sf
Volume Required
VR=Ax1800 cf/ac A= 6.8
VR= 12240
Volume Proposed
Vp=((Top Area + Bottom Area)/2)xD Top= 10082
Bottom= 4418
VP= 14500 D= 2
OK
Weir Sizing
Per AutoCad Hydraflow Software
L= 10 ft
D= 2 ft
dwater= 0.92 ft
Q25= 23.0384 cfs

Velocity= 2.5 ft/s
Weir Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 0.92 ft
T= 0.57408 lbs/ft2 s= 0.01 ft/ft
Use Class A Rip Rap
Skimmer Sizing
RE
Calculate Dewater Time
Qd=V/Td V= 12240
Td= 3 2-5 days typ
Qd= 4080
Calculate Orifice Diameter
D=sgrt((Qd/(2310sgrt(h))) Qd= 4080
h= 0.33
D= 1.007285
Use 4 " Skimmers 1.0 Orifice
Skimmer Outlet Protection
New York Method 8.06.5 Manual
Diameter of Barrel = 4.00 " La= 1.32 Use 7.5 ft
Velocity= 2.36 ft/s W= 1 Use 3.0 ft
Zone= 1 d= 12"
Stone Diameter= Class A

Skimmer Basin# 2
Calculate Flow- Rational Method
10-Yr Storm 25-Yr Storm
Q10= CIA C= 0.4 Q25=CIA C= 0.4
1= 7.72 1= 8.47
Q10= 32.424 A= 10.5 Q25 = 35.574 A= 10.5
Calculate Required Surface Area
SA=Q10 x 325 sf/cfs Q10= 32.424 cfs
SA= 10537.8
Side Slopes= 3 :1
Pond Depth= 2 ft
Basin Dims
Top= 86 x 172 = 14792 sf
Weir= 74 x 148 = 10952 sf
Bottom = 62 x 124 = 7688 sf
Volume Required
VR=Ax1800 cf/ac A= 10.5
VR= 18900
Volume Proposed
Vp=((Top Area + Bottom Area)/2)xD Top= 14792
Bottom= 7688
VP= 22480 D= 2
OK
Weir Sizing
Per AutoCad Hydraflow Software
L= 15 ft
D= 2 ft
dwater= 0.94 ft
Q25= 35.574 cfs

Velocity= 2.52 ft/s
Weir Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 0.94 ft
T= 0.58656 lbs/ft2 s= 0.01 ft/ft
Use Class A Rip Rap
Skimmer Sizing
RE
Calculate Dewater Time
Qd=V/Td V= 18900
Td= 3 2-5 days typ
Qd= 6300
Calculate Orifice Diameter
D=sgrt((Qd/(2310sgrt(h))) Qd= 6300
h= 0.33
D= 1.251678
Use 4 " Skimmers 1.3 Orifice
Skimmer Outlet Protection
New York Method 8.06.5 Manual
Diameter of Barrel = 4.00 " La= 1.32 Use 7.5 ft
Velocity= 2.36 ft/s W= 1 Use 3.0 ft
Zone= 1 d= 12"
Stone Diameter= Class A

Skimmer Basin# 3
Calculate Flow- Rational Method
10-Yr Storm 25-Yr Storm
010= CIA C= 0.4 Q25=CIA C= 0.4
1= 7.78 1= 8.59
Q10= 27.0744 A= 8.7 Q25 = 29.8932 A= 8.7
Calculate Required Surface Area
SA=Q10 x 325 sf/cfs 010= 27.0744 cfs
SA= 8799.18
Side Slopes= 3 :1
Pond Depth= 2 ft
Basin Dims
Top= 79 x 158 = 12482 sf
Weir= 67 x 134 = 8978 sf
Bottom = 55 x 110 = 6050 sf
Volume Required
VR=Ax1800 cf/ac A= 8.7
VR= 15660
Volume Proposed
Vp=((Top Area + Bottom Area)/2)xD Top= 12482
Bottom= 6050
VP= 18532 D= 2
OK
Weir Sizing
Per AutoCad Hydraflow Software
L= 15 ft
D= 2 ft
dwater= 0.84 ft
Q25= 29.8932 cfs

Velocity= 2.38 ft/s
Weir Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 0.84 ft
T= 0.52416 lbs/ft2 s= 0.01 ft/ft
Use Class A Rip Rap
Skimmer Sizing
RE
Calculate Dewater Time
Qd=V/Td V= 15660
Td= 3 2-5 days typ
Qd= 5220
Calculate Orifice Diameter
D=sgrt((Qd/(2310sgrt(h))) Qd= 5220
h= 0.33
D= 1.139352
Use 4 " Skimmers 1.1 Orifice
Skimmer Outlet Protection
New York Method 8.06.5 Manual
Diameter of Barrel = 4.00 " La= 1.32 Use 7.5 ft
Velocity= 2.36 ft/s W= 1 Use 3.0 ft
Zone= 1 d= 12"
Stone Diameter= Class A

Skimmer Basin# 4
Calculate Flow- Rational Method
10-Yr Storm 25-Yr Storm
010= CIA C= 0.5 Q25=CIA C= 0.5
1= 7.72 1= 8.47
Q10= 28.1008 A= 7.28 Q25 = 30.8308 A= 7.28
Calculate Required Surface Area
SA=Q10 x 325 sf/cfs 010= 28.1008 cfs
SA= 9132.76
Side Slopes= 3 :1
Pond Depth= 2 ft
Basin Dims
Top= 80 x 160 = 12800 sf
Weir= 68 x 136 = 9248 sf
Bottom = 56 x 112 = 6272 sf
Volume Required
VR=Ax1800 cf/ac A= 7.28
VR= 13104
Volume Proposed
Vp=((Top Area + Bottom Area)/2)xD Top= 12800
Bottom= 6272
VP= 19072 D= 2
OK
Weir Sizing
Per AutoCad Hydraflow Software
L= 15 ft
D= 2 ft
dwater= 0.85 ft
Q25= 30.8308 cfs

Velocity= 2.4 ft/s
Weir Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 0.85 ft
T= 0.5304 Ibs/ft2 s= 0.01 ft/ft
Use Class A Rip Rap
Skimmer Sizing
RE
Calculate Dewater Time
Qd=V/Td V= 13104
Td= 3 2-5 days typ
Qd= 4368
Calculate Orifice Diameter
D=sgrt((Qd/(2310sgrt(h))) Qd= 4368
h= 0.33
D= 1.042231
Use 4 " Skimmers 1.0 Orifice
Skimmer Outlet Protection
New York Method 8.06.5 Manual
Diameter of Barrel = 4.00 " La= 1.32 Use 7.5 ft
Velocity= 2.36 ft/s W= 1 Use 3.0 ft
Zone= 1 d= 12"
Stone Diameter= Class A

Temporary Diversion# 100 =>DA# 100
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.40
1= 8.89 in/hr
Q25= 20.62 A= 5.80 ac
Channel Slope= 0.50
Channel Depth= 2.00
Channel Bottom W= 0
Side Slopes= 3.00
Velocity= 3.55
Soil Type @ sandy loarr Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 1.39 ft
T= 0.43368 lbs/ft2 s= 0.005 ft/ft
Temporary= NAG S75BN
Permanent= Bermudagrass 6
Temporary Diversion# 200 =>DA# 200
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.40
1= 8.89 in/hr
Q25= 30.94 A= 8.70 ac
Channel Slope= 5.00 WORSE CASE
Channel Depth= 2.00
Channel Bottom W= 0
Side Slopes= 3.00
Velocity= 9.30
Soil Type @ sandy loarr Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 1.05 ft
T= 3.276 lbs/ft2 s= 0.05 ft/ft
Temporary= NAG P300
Permanent= Bermudagrass

Temporary Diversion# 300 =>DA# 300
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.40
1= 8.89 in/hr
Q25= 1.78 A= 0.50 ac
Channel Slope= 0.50
Channel Depth= 1.00
Channel Bottom W= 0
Side Slopes= 3.00
Velocity= 1.89
Soil Type @ sandy loan Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 0.56 ft
T= 0.17472 lbs/ft2 s= 0.005 ft/ft
Temporary= NAG S75BN
Permanent= Bermudagrass
Temporary Diversion# 400 =>DA# 400
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.40
1= 8.89 in/hr
Q25= 27.03 A= 7.60 ac
Channel Slope= 0.50
Channel Depth= 2.00
Channel Bottom W= 0
Side Slopes= 3.00
Velocity= 3.84
Soil Type @ sandy loarr Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater 1.5 ft
T= 0.468 lbs/ft2 s= 0.005 ft/ft
Temporary= NAG S150BN
Permanent= Bermudagrass

Temporary Diversion# 500 =>DA# 500
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.40
1= 8.89 in/hr
Q25= 18.49 A= 5.20 ac
Channel Slope= 0.50
Channel Depth= 2.00
Channel Bottom W= 0
Side Slopes= 3.00
Velocity= 3.48
Soil Type @ sandy loan Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater 1.3 ft
T= 0.4056 lbs/ft2 s= 0.005 ft/ft
Temporary= NAG S150BN
Permanent= Bermudagrass
Temporary Diversion# 600 =>DA# 600
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.40
1= 8.89 in/hr
Q25= 5.33 A= 1.50 ac
Channel Slope= 5.00 WORSE CASE
Channel Depth= 1.00
Channel Bottom W= 0
Side Slopes= 3.00
Velocity= 6.00
Soil Type @ sandy loarr Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater 0.5 ft
T= 1.56 lbs/ft2 s= 0.05 ft/ft
Temporary= NAG S150BN
Permanent= Bermudagrass

Temporary Diversion# 700A =>DA# 600A
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.30
1= 5.37 in/hr TC CALC
Q25= 15.59 A= 9.68 ac
Channel Slope= 0.50
Channel Depth= 1.50
Channel Bottom W= 0
Side Slopes= 3.00
Velocity= 3.30
Soil Type @ sandy loarr Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 1.25 ft
T= 0.39 Ibs/ft2 s= 0.005 ft/ft
Temporary= NAG S150BN
Permanent= Bermudagrass
Temporary Diversion# 700B =>DA# 600B
Calculate Flow-Rational Method
25-Yr Storm
Q25=CIA C= 0.40
1= 5.37 in/hr TC CALC
Q25= 45.11 A= 21.00 ac
Channel Slope= 0.50
Channel Depth= 1.50
Channel Bottom W= 2
Side Slopes= 3.00
Velocity= 5.59
Soil Type @ sandy loarr Slopes= 0-5
Channel Lining
Shear Calculation
T=yds y= 62.4 lbs
dwater= 1.34 ft
T= 0.41808 lbs/ft2 s= 0.005 ft/ft
Temporary= NAG S150BN
Permanent= Bermudagrass

U.S. Department of Agriculture FL-ENG-21 B
Natural Resources Conservation Service 06/04
TR 55 Worksheet 3: Time of Concentration (Ta) or Travel Time (Tt)
Project: Buffalo Creek Subdivison Designed By: MTB Date:
Location: Hoke County, NC Checked By: JH Date:
Check one: Present Developed
Check one: ,/ Tc Tt through subarea TD 600 A
NOTES: Space for as many as two segments per flow type can be used for each worksheet. Include a map, schematic,
or description of flow segments.
Sheet Flow (Applicable to T, only) Segment ID 1
1. Surface description (Table 3-1) GRASS
2. Manning's roughness coeff., n (Table 3-1) 0.04
3. Flow length, L (total L < 100 ft) ft 100
4. Two-year 24-hour rainfall, P2 in 0.1
5. Land slope, s ft/ft 0.050
6. Tt = 0.007 (nL)0.8 Compute Tt hr 0.18 + = 0.18
P2(15
S0.4
Shallow Concetrated Flow Segment ID 2
7. Surface description (paved or unpaved) UNPAVED
8. Flow length, L ft 900
9. Watercourse slope, s ft/ft 0.013
10. Average velocity, V (Figure 3-1) ft/s 1.5
11. Tt = L Compute Tt hr 0.17 + = 0.17
3600 V
Channel Flow Segment ID
12. Cross sectional flow area, a ft2 0.0
13. Wetted perimeter, Pw ft 0.0
14. Hydraulic radius, r= a Compute r ft
Pw
15. Channel Slope, s ft/ft 0.000
16. Manning's Roughness Coeff., n 0.00
17. V = 1.49 r2/3 s112 Compute V ft/s 2.7
n
18. Flow length, L ft 0
19. Tt = L Compute Tt hr + _
3600 V
20. Watershed or subarea Tc or Tt(add Tt in steps 6, 11, and 19 hr 0.35
0.35= 21.0 mins

Outlet Protection#100
New York Method 8.06.5 Manual
Q= 57.32 cfs La= 24 FT
Pipe Diameter 36 in W= 9 FT
Velocity= 10.2 ft/s d= 24 IN
Zone= 3 Stone Diameter=Class 1
Outlet Protection#104
New York Method 8.06.5 Manual
Q= 17.09 cfs La= 16 FT
Pipe Diameter 24 ft W= 6 FT
Velocity= 5.57 ft/s d= 18 IN
Zone= 2 Stone Diameter=Class B
Outlet Protection#200
New York Method 8.06.5 Manual
Q= 6.14 cfs La= 5 FT
Pipe Diameter 15 ft W= 4 FT
Velocity= 7.23 ft/s d= 12 IN
Zone= 1 Stone Diameter=Class A
Outlet Protection#300
New York Method 8.06.5 Manual
Q= 4.89 cfs La= 5 FT
Pipe Diameter 15 in W= 4 FT
Velocity= 7.2 ft/s d= 12 IN
Zone= 1 Stone Diameter=Class A
Outlet Protection#400
New York Method 8.06.5 Manual
Q= 4.3 cfs La= 5 FT
Pipe Diameter 15 in W= 4 FT
Velocity= 6.6 ft/s d= 12 IN
Zone= 1 Stone Diameter=Class A
Outlet Protection#500
New York Method 8.06.5 Manual
Q= 6.14 cfs La= 5 FT
Pipe Diameter 15 in W= 4 FT
Velocity= 7.23 ft/s d= 12 IN
Zone= 1 Stone Diameter=Class A
Outlet Protection#600
New York Method 8.06.5 Manual
Q= 7.43 cfs La= 5 FT
Pipe Diameter 15 in W= 4 FT
Velocity= 4.94 ft/s d= 12 IN
Zone= 1 Stone Diameter=Class A

APPENDIX B
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J THOMAS ENGINEERING, INC.
CIVIL ENGINEERING 8, PLANNING
143 Charlotte Avenue,Suite 104
Sanford,North Carolina 27330
[phone] phone
www.jthomasengineering.com
license no.C-3389
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PRELIMINARY
DO NOT USE FORCONSTRUCTION(Pt*.
Scale: Drawn by: D
Z 1"=150' MTB
Sheet: Designed by: i
JRT
Reviewed by:
150 0 75 150 300 DA 1 of 2 JRT
Project Number: Date: Pti
SCALE:1"=150' DD S.
2019-23 JULY 24,2020
d"

J THOMAS ENGINEERING, INC.
CIVIL ENGINEERING 8, PLANNING
143 Charlotte Avenue,Suite 104
Sanford,North Carolina 27330
[phone] phone
www.jthomasengineering.com
license no.C-3389
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PRELIMINARY
` DO NOT USE FOR
/.LOB CONSTRUCTION
Scale: Drawn by: c
Z 1"=150' MTB i'n
Sheet: Designed by: i
JRT
Reviewed by: _
150 0 75 150 300 DA 1 of 2 JRT
Project Number: Date: �i
SCALE:1"=150' DD S.
2019-23 JULY 24,2020
d"

APPENDIX D
S© U SuN©y G ap

Soil Map—Hoke County, North Carolina O3O
M ..
O
N (..,
649800 649900 650000 650100 650200 650300 650400 6505W 650600 6507W 650800 65095) 651000
34°59'24"N I 34°59'24"N
8
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X
34°58'55"N 34°58'55"N
649800 649900 650000 650100 650200 650300 650400 650500 650600 650750 650800 650900 651000 651100
3 3
Map Scale:1:6,200 if printed on A landscape(11"x 8.5")sheet.
Meters N
N
0 50 100 200 300 °k'
Feet
0 300 600 1200 1800
Map projection:Web Mercator Comer coordinates:WGS84 Edge tics:UTM Zone 17N WGS84
USDA Natural Resources Web Soil Survey 8/24/2023
Conservation Service National Cooperative Soil Survey Page 1 of 3

Soil Map—Hoke County,North Carolina
MAP LEGEND MAP INFORMATION
Area of Interest(AOI) Spoil Area The soil surveys that comprise your AOI were mapped at
Area of Interest(AOI) 1:24,000.
Q Stony Spot
Soils 44 Very Stony Spot Warning:Soil Map may not be valid at this scale.
0 Soil Map Unit Polygons
Wet Spot Enlargement of maps beyond the scale of mapping can cause
.�� Soil Map Unit Lines misunderstanding of the detail of mapping and accuracy of soil
Other line placement.The maps do not show the small areas of
p Soil Map Unit Points contrasting soils that could have been shown at a more detailed
Special Line Features
Special Point Features scale.
w Blowout Water Features
Streams and Canals Please rely on the bar scale on each map sheet for map
cs Borrow Pit measurements.
Transportation
X Clay Spot Rails Source of Map: Natural Resources Conservation Service
0 Closed Depression Web Soil Survey URL:
ti Interstate Highways Coordinate System: Web Mercator(EPSG:3857)
X Gravel Pit US Routes
Maps from the Web Soil Survey are based on the Web Mercator
,. Gravelly Spot Major Roads projection,which preserves direction and shape but distorts
distance and area.A projection that preserves area,such as the
0 Landfill Local Roads Albers equal-area conic projection,should be used if more
Lava Flow accurate calculations of distance or area are required.
Background
46 Marsh or swamp Aerial Photography This product is generated from the USDA-NRCS certified data as
of the version date(s)listed below.
iRk Mine or Quarry
Soil Survey Area: Hoke County,North Carolina
O Miscellaneous Water Survey Area Data: Version 20,Sep 8,2022
Q Perennial Water Soil map units are labeled(as space allows)for map scales
v Rock Outcrop 1:50,000 or larger.
▪ Saline Spot Date(s)aerial images were photographed: Apr 17,2022—May
20,2022
Sandy Spot
The orthophoto or other base map on which the soil lines were
Severely Eroded Spot compiled and digitized probably differs from the background
imagery displayed on these maps.As a result,some minor
• Sinkhole shifting of map unit boundaries may be evident.
3) Slide or Slip
oa Sodic Spot
Natural Resources Web Soil Survey 8/24/2023
Conservation Service National Cooperative Soil Survey Page 2 of 3

Soil Map—Hoke County, North Carolina
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
BaB Blaney loamy sand,2 to 8 14.0 9.5%
percent slopes
BaD Blaney loamy sand,8 to 15 2.8 1.9%
percent slopes
DhA Dothan loamy sand,0 to 2 33.5 22.7%
percent slopes
FuB Fuquay sand,0 to 4 percent 52.3 35.5%
slopes
GdB Gilead loamy sand,2 to 8 0.1 0.0%
percent slopes
JT Johnston loam 24.4 16.5%
Pg I Pantego loam 4.6 3.1%
VaD Vaucluse loamy sand,8 to 15 15.7 10.6%
percent slopes
Totals for Area of Interest 147.5 100.0%
usm Natural Resources Web Soil Survey 8/24/2023
Conservation Service National Cooperative Soil Survey Page 3 of 3

APPENDIX E
PlNIA Piim Map

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APPENDIX E

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APPENDIX E
SVO 3MM/Q' 3 PO_
ZIMQUEMHV
MP SUPP MM lr OEM

SUPPLEMENT-EZ COVER PAGE
FORMS LOADED
PROJECT INFORMATION
1 Project Name Buffalo Creek Subdivision
2 Project Area(ac) 52.2
3 Coastal Wetland Area(ac)
4 Surface Water Area(ac) 0
5 Is this project High or Low Density? Low
6 Does this project use an off-site SCM? No
COMPLIANCE WITH 02H.1003(4)
7 Width of vegetated setbacks provided(feet) 30
8 Will the vegetated setback remain vegetated? Yes
9 If BUA is proposed in the setback,does it meet NCAC 02H.1003(4)(c-d)? Yes
10 Is streambank stabilization proposed on this project? No
NUMBER AND TYPE OF SCMs:
11 Infiltration System 0
12 Bioretention Cell 0
13 Wet Pond 0
14 Stormwater Wetland 0
15 Permeable Pavement 0
16 Sand Filter 0
17 Rainwater Harvesting(RWH) 0
18 Green Roof 0
19 Level Spreader-Filter Strip(LS-FS) 0
20 Disconnected Impervious Surface(DIS) 0
21 Treatment Swale 0
22 Dry Pond 0
23 StormFilter 0
24 Silva Cell 0
25 Bayfilter 0
26 Filterra 0
FORMS LOADED
DESIGNER CERTIFICATION
27 Name and Title: Jarrod E.Hilliard, PE
28 Organization: Hilliard Engineering,PLLC.
29 Street address: P.O.Box 249
30 City,State,Zip: Sanford,NC 27331
31 Phone number(s): [phone]
32 Email: [e-mail]
Certification Statement:
I certify,under penalty of law that this Supplement-EZ form and all supporting information were prepared under my direction or supervision;that
the information provided in the form is,to the best of my knowledge and belief,true,accurate,and complete;and that the engineering plans,
specifications,operation and maintenance agreements and other supporting information are consistent with the information provided here.
Designer
ON CA00
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SEAL ••• - Signature of Designer
• 035670 •
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iiea!`11\�\ Date

DRAINAGE AREAS
1 Is this a high density project? No
2 If so,number of drainage areas/SCMs _ 0
3 Does this project have low density areas? _ Yes
4 If so,number of low density drainage areas _ 3
Is all/part of this project subject to previous rule
5 versions? No
FORMS LOADED
DRAINAGE AREA INFORMATION Entire Site LD 1 LD 2 LD 3
4 Type of SCM
5 Total drainage area(sq ft) 1023660 788436 165528 69696
6 Onsite drainage area(sq ft) 1023660 788436 165528 69696
7 Offsite drainage area(sq ft)
8 Total BUA in project(sq ft) 323151 sf 248895 sf 52254 sf 22002 sf
New BUA on subdivided lots(subject to
9 permitting)(sq ft) 164500 sf 52500 sf 35000 sf 7000 sf
New BUA not on subdivided lots(subject to
10 permitting)(sf) 158651 sf 196395 sf 17254 sf 15002 sf
11 Offsite BUA(sq ft)
12 Breakdown of new BUA not on subdivided lots:
-Parking(sq ft)
-Sidewalk(sq ft) 22177 sf 17076 sf 3548 sf 1553 sf
-Roof(sq ft)
-Roadway(sq ft) 136474 sf 105084 sf 21835 sf 9555 sf
-Future(sq ft)
-Other,please specify in the comment box
below(sq ft)
New infiltrating permeable pavement on
13 subdivided lots(sq ft)
New infiltrating permeable pavement not on
14 subdivided lots(sq ft)
Existing BUA that will remain(not subject to
15 permitting)(sq ft)
16 Existing BUA that is already permitted(sq ft)
17 Existing BUA that will be removed(sq ft)
18 Percent BUA 15% 32% 32% 32%
19 Design storm(inches)
20 Design volume of SCM(cu ft)
21 Calculation method for design volume
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the
22 drainage area(s):
Percent BUA is based on total project area.

LOW DENSITY
DESIGN REQUIREMENTS FOR LOW DENSITY PROJECTS FROM 02H.1003
1 Is project below density thresholds set forth in the applicable stormwater rule? Yes
2 Does project maximize dispersed flow and minimize channelization of flow? Yes
3 Has the use of piping been minimized per.1003(2)(c)? Yes
4 Side slopes of the vegetated conveyances(H:V) I 3 sf
5 Maximum velocity in the vegetated conveyances during the 10-year storm? 3.04
6 Are curb outlet swales proposed? Yes
7 Maximum longitudinal slope of curb outlet swale(s)(%) 7%
8 Bottom width of curb outlet swale(s)(feet) 3 ft
9 Maximum side slope of curb outlet swale(s)(H:V) 3:1
10 Minimum length of curb outlet swale(s)(feet) 100 ft
11 Are treatment swales used instead of curb outlet swales? No
12 Is stormwater released at the edge of the setback as dispersed flow? No
13 Have stormwater outlets been designed to prevent downslope erosion? Yes
14 Are variations to rule.1003 proposed? No
ADDITIONAL INFORMATION
15 Please use this space to provide any additional information about this low density project:
*BUA&Pervious areas are for the swale drainage areas only
Drainage Pervious
Swale BUA Q Slope V,i„w V,a.i Flow depth
# Area area
(ac) (cfs) (%) (fps) (fps) (ft)
(ac) (ac)
1 18.10 5.7* 12.4* 0.35 57.32 1.00 6.00 3.04 1.80
2 3.80 1.19* 2.26* 0.35 11.24 0.50 5.00 1.53 1.03
3 1.80 0.50* 1.30* 0.35 4.89 1.80 5.00 3.18 0.35
4
5
6
i_
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
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30

Low Density Maintenance Requirements
Important maintenance procedures:
The drainage area to the vegetated conveyance or vegetated receiving area will be carefully managed
to reduce the sediment load to the vegetated conveyance or vegetated receiving area.
After the initial fertilization to establish the grass in the vegetated conveyance or the vegetated
receiving area, fertilizer will not be applied to the vegetated receiving areas.
The vegetated conveyance or vegetated receiving area will be inspected quarterly . Records of operation and
maintenance will be kept in a known set location and will be available upon request.
Inspection activities shall be performed as follows. Any problems that are found shall be repaired immediately.
SCM element: Potential problem: How to remediate the problem:
Vegetation Vegetation is too short or Maintain grassed vegetation such that the swale or vegetated
too long. area does not erode during the peak flow from the 10-year storm
Trash/debris is present. Remove the trash/debris.
Areas of bare soil and/or Regrade the soil if necessary to remove the gully, and then re-
erosive gullies have sod (or plant with other appropriate species) and water until
Vegetated receiving formed. established. Provide lime and a one-time fertilizer application.
areas
Trees and/or other woody Remove the trees and woody vegetation from the swale, regrade
vegetation are present in the swale if necessary and re-establish grass as shown on the
the swale. approved plans.
Trash/debris is present. Remove the trash/debris.
Areas of bare soil and/or Regrade the soil if necessary to remove the gully, and then re-
erosive gullies have sod (or plant with other appropriate species) and water until
formed. established. Provide lime and a one-time fertilizer application.
Sediment covers the grass Remove sediment and dispose in an area that will not impact
at the bottom of the swale. streams or SCMs. Re-sod if necessary.
Vegetated conveyances
/swales / roadside Regrade the slopes to the permitted configuration per the
ditches (other than curb The side slope is steeper
than the approved
approved plan and reestablish vegetation. If as-built or existing
outlet swales) conditions do not allow the slopes to be regraded, contact the
configuration.
applicable permitting agency.
Determine the source of the problem: soils, hydrology, disease,
Grass is dead, diseased or
etc. Remedy the problem and replace plants. Provide a one-time
dying. fertilizer application to establish the ground cover if necessary.
Trees and/or other woody Remove the trees and woody vegetation from the vegetated
vegetation are present in conveyance, regrade the vegetated conveyance if necessary
the vegetated conveyance. and re-establish grass as shown on the approved plans.

The longitudinal slope Regrade to meet the permitted longitudinal slope as shown on the
exceeds 5%. approved plans.
Curb outlet swales or The swale profile does not Regrade the swale to the approved profile as shown on the
vegetated areas match the approved detail. approved plans.
The length of the swale or Extend the swale to achieve the 100-foot minimum length. If as-
vegetated area is less built or existing conditions do not allow the slopes to be regraded,
than 100 feet. contact the applicable permitting agency.
Clogging has occurred. Clean out the outlet device. Dispose of the sediment off-site.
The outlet device (if
applicable)
The outlet device is Repair or replace the outlet device.
damaged
Erosion or other signs of
damage have occurred at Repair the damage and improve the flow dissipation structure.
the outlet.
The receiving water Discharges from the site
are causing erosion or
sedimentation in the Contact the local NCDEQ Regional Office.
receiving water.

Permit Number:
(to be provided by DWQ)
OF WAAFICirassA &4 ")c
TF9
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out,printed and submitted.
The Required Items Checklist(Part III)must also be filled out,printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Buffalo Creek Subdivision
Contact name Michael Blakley
Phone number [phone]
Date August 25,2023
Drainage area number 100
II. DESIGN INFORMATION
Site Characteristics
Drainage area 788,436.00 ft2
Impervious area 248,895.00 ft2
Percent impervious 31.6% %
Design rainfall depth 3.04 inch
Peak Flow Calculations
10-yr storm runoff depth 5.44 in
10-yr storm intensity 8.89 in/hr
Post-development 10-yr storm peak flow 57.32 ft3/sec
Velocity
Maximum non-erosive velocity(peak 10-year storm) 5.00 ft/sec
Soil characteristics(enter"x"below)
Sand/silt(easily erodible) x
Clay mix(erosion resistant)
Grass Type(enter"x"below)
Bermuda x
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: y (Y or N)
Maximum velocity 3.04 OK
Side slopes 3.00 :1 Insufficient side slopes.Max is 5:1.
Swale length 100.00 ft OK
Option 2: Swale Seeking Pollutant Credit("For-Credit"Swale): n (Y or N)
Maximum velocity for 10-yr storm ft/sec
Side slopes :1
Swale length ft
Form SW401-Grassed Swale-Rev.4 Parts I and II.Project Design Summary,Page 1 of 2

Permit Number:
(to be provided by DWQ)
Swale Characteristics
Swale Shape:Enter an"x"in the appropriate cell below:
Trapezoidal x
Parabolic
V-shaped
Width of the bottom of the swale 3.00 ft
Width of the top of the swale 12.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? y(Y or N) OK
Is the BMP located in a proposed drainage easement with a y(Y or N) OK
recorded access easement to a public Right of Way(ROW)?
What is the distance from the bottom of the swale to the SHWT? 14.25 ft OK
What is the ground level elevation? 276.00 fmsl
What is the elevation of the bottom of the swale? 274.25 fmsl
What is the SHWT elevation? 260.00 fmsl
What is the longitudinal slope of the swale? 1.00 % OK
What is the depth of freeboard? 0.70 ft OK
Form SW401-Grassed Swale-Rev.4 Parts I and II.Project Design Summary,Page 2 of 2

Permit Number:
(to be provided by DWQ)
OF W AT9
A741,11;irA
� r
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
GRASSED SWALE SUPPLEMENT
This form must be filled out,printed and submitted.
The Required Items Checklist(Part III)must also be filled out,printed and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name Buffalo Creek Subdivision
Contact name Michael Blakley
Phone number [phone]
Date August 25,2023
Drainage area number 300
II. DESIGN INFORMATION
Site Characteristics
Drainage area 69,696.00 ft2
Impervious area 22,002.00 ft2
Percent impervious 31.6% %
Design rainfall depth 3.04 inch
Peak Flow Calculations
10-yr storm runoff depth 5.44 in
10-yr storm intensity 8.89 in/hr
Post-development 10-yr storm peak flow 4.89 ft3/sec
Velocity
Maximum non-erosive velocity(peak 10-year storm) 5.00 ft/sec
Soil characteristics(enter"x"below)
Sand/silt(easily erodible) x
Clay mix(erosion resistant)
Grass Type(enter"x"below)
Bermuda x
Tall fescue
Bahiagrass
Kentucky bluegrass
Grass-legume mixture
Swale type: Fill out one of the options below:
Option 1: Curb Outlet Swale: y (Y or N)
Maximum velocity 3.18 OK
Side slopes 3.00 :1 Insufficient side slopes.Max is 5:1.
Swale length 100.00 ft OK
Option 2: Swale Seeking Pollutant Credit("For-Credit"Swale): n (Y or N)
Maximum velocity for 10-yr storm ft/sec
Side slopes :1
Swale length ft
Form SW401-Grassed Swale-Rev.4 Parts I and II.Project Design Summary,Page 1 of 2

Permit Number:
(to be provided by DWQ)
Swale Characteristics
Swale Shape:Enter an"x"in the appropriate cell below:
Trapezoidal x
Parabolic
V-shaped
Width of the bottom of the swale 3.00 ft
Width of the top of the swale 12.00 ft
Additional Information
Is the swale sized for all runoff from ultimate build-out? y(Y or N) OK
Is the BMP located in a proposed drainage easement with a y(Y or N) OK
recorded access easement to a public Right of Way(ROW)?
What is the distance from the bottom of the swale to the SHWT? 18.00 ft OK
What is the ground level elevation? 276.00 fmsl
What is the elevation of the bottom of the swale? 278.00 fmsl
What is the SHWT elevation? 260.00 fmsl
What is the longitudinal slope of the swale? 1.80 % OK
What is the depth of freeboard? 1.00 ft OK
Form SW401-Grassed Swale-Rev.4 Parts I and II.Project Design Summary,Page 2 of 2