SW5240402_Stormwater Narrative_20240422

c Stormwater Project Narrative
(1Zil;
Environmental' Highland Place Subdivision
Lots 32 thru 63 and Lots 89 thru 120
Project Name: Highland Place Subdivision
DEQ Permit ID TBD
Project Address:Allie Clay Road,Roxboro,NC
Lat/ Long at Project Entrance: 36.432075° N, -78.9639°W Land
Owner: David Bradley Walker.
Mailing Address: 1125 Walker Field Drive, Rougemont, NC 27572
Owner Contact: Mr. Brad Walker
Owner Contact Email: [e-mail]
Owner Contact Phone: [phone]
Plan Preparer: Jesse W. Wilson, P.E.
Address: 1001 Chestnut Drive, Smithfield, NC27577 Phone: (336)
736-9267 Email: [e-mail]
Project Description:
This final portion of the subdivision is contained within a 120 Lot subdivision off Allie Clay Road in
Roxboro,NC. The subdivision concept plan,along with the design Plans were originally approved by
Person County in 2002. Phase I of the subdivision (Lots 1 thru 31)was constructed shortly after plan
approval in 2002. The City of Roxboro has annexed the remainder of the subdivision,and the second
Phase (Lots 64 thru 89) is currently under construction.
The final portion of the subdivision consist of 64 total lots (Lots 32 trhu 63 and Lots 89 thru 120).The
final portion of the subdivision requires a new Grading&Erosion Control Permit and a Post
Contruction Stormwater Management Permit prior to initiating construction.
Existing Site Conditions:The proposed construction area is rolling flat with slopes ranging from 2 to
11%. No pre-2006 impervious conditions exist.
Stormwater Runoff:Temporary Sediment Basins 1 thru 5 will control offsite siltation. Temporary
Diversion Ditches will be installed to direct sediment laiden runoff to the Temporary Sediment Basins.
Offsite Runoff will be diverted with the installation of Permanent Clear Water Ditches.The increase in
impervious area(1.04 Acres)will increase the peak runoff during the 10-year storm from 78.87 cfs to
113.28 cfs.
Adjacent Areas:
The areas adjoining the site are residentially zoned.
Off-site Land-Disturbing Areas:
There will be no off-site Land-disturbing Activities or Areas associated with this construction.
Soils -See Appendix A
Soil Types:
GeB—23.9%of Area of Interest(AOI),HeB - 10.2%AOI,HrB - 51.7%AOI,IrB 13.2%AOI;
Critical Areas:
There are no critical areas on the site in terms of stream and wetland buffers.
Erosion &Sediment Control Measures—See Appendices B& C:
The Erosion and Sediment Control Measures slated for construction, as well as the Construction
Sequence are shown on Sheets 2 and 3 of the Grading& Erosion Control Plan Set,with construction
details and maintenance schedules shown on Sheet 5.

Project Narrative & Pertinent Calculations
Z4ose
°°��t°' Highland Place Subdivision
Permanent Stabilization:
The majority of the disturbed area for the project will be stabilized by asphalt pavement (roads).The
remaining disturbed areas will be permanently stabilized by vegetation (grass) as follows:
Seeding Specification & Rate -Tall Fescue (Ky 31), 80- 100 lbs per acre
Fertilizer Rate- 1000 lbs per acre 10-20-10 PKN
Liming Rate- 1 tons per acre pulverized agricultural grade limestone
Mulching Type/ Rate-Straw/4,000 lbs per acre.
Property Area:
Total property:25.23 Acres
Impervious Areas—See Appendix D:
The property area is 25.23 acres. The existing stream area represents approximately 3,781 square
feet(sf) as measured from bank to bank,thus the total project drainage area is reduced to 25.15
Acres.The project will have a maximum Built Upon Area (BUA) of 262,781.9 sf(23.99%).The
proposed roads (76,860 sf) represent approximately 7.02%of the proposed BUA. The remaining
17(+/-)%will be divided equally amongst the proposed 64 Lots yeilding a maximum BUA of
2,905.01 square feet per Lot.
Impervious Area Summary—
Total Property Area (25.23 Ac.)
Total pre-2006 Impervious Area: 0.00-acres
24% High Density Threshold—6.03Acres
APPENDICES
A. Soils Map
B. Sediment Basin Calculations
C. Impervious Area Summary Spreadsheet
D. Permanent Ditchline Calculations for Erosive Velocity
E. Diversion Ditch Calculations for Erosive Velocity
F. Culvert Sizing Calculations

APPENDIX A - SOILS MAP
Soil Map—Person County,North Carolina
(Highland Place Subdivision)
682400 682480 682560 682610 682720 682800 682880
36°26'0"N I 36°26'0"N
! /f ¢
-
GeB
•
.c• a._ -
H.
~ ,p
1 `
N s
o
tt. . . •
•
. 4,
1
1 .,.. .
,..,_
,.......
. ' . t
N1114\40:\,
V
s` ApC 4,
lap E be v a[Ird aft t Gd..y;flgaOQo AitAit?
1
36°25'37"N ""z 36°25'37'N
682400 682480 682560 682640 682720 682800 682880
3 3
F Map Scale:1:3,440 if printed on A portrait(8.5"x 11")sheet.
Meters
N 0 50 100 200 300
Feet
0 150 300 600 900
Map projedion:Web Mercator Comer coordinates:WGS84 Edge tics:UTM Zone 17N WGS84
USDA Natural Resources Web Soil Survey 3/11/2024
Conservation Service National Cooperative Soil Survey Page 1 of 3

Soil Map—Person County,North Carolina
(Highland Place Subdivision)
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.
(o, 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: Person County,North Carolina
O Miscellaneous Water Survey Area Data: Version 26,Sep 13,2023
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 25,2022—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
l'til)\ Natural Resources Web Soil Survey 3/11/2024
Conservation Service National Cooperative Soil Survey Page 2 of 3

Soil Map—Person County,North Carolina Highland Place Subdivision
Map Unit Legend
Map Unit Symbol ' Map Unit Name Acres in AOI Percent of AOI
ApC Appling sandy loam,6 to 10 0.2 1.0%
percent slopes
GeB Georgeville loam,2 to 6 5.3 23.9%
percent slopes
HeB Helena sandy loam,2 to 6 2.3 10.2%
percent slopes
HrB Herndon loam,2 to 6 percent 11.4 51.7%
slopes
IrB Iredell gravelly loam,2 to 6 2.9 13.2%
percent slopes
Totals for Area of Interest 22.1 100.0%
USDA Natural Resources Web Soil Survey 3/11/2024
Conservation Service National Cooperative Soil Survey Page 3 of 3

APPENDIX B
Temporary Sediment Basin Sizes - Preliminary Rectangular Sizing
Highland Place Subdivision, Roxboro, NC
10-Year Intensity = 6.97
Keq-a - - - - - - -
Sed. Req'd Req'd Iterative Design Sed. Slop
Skim. Drain. Dist. Storage Req'd. Top Top Top S/A S/A Top Resulting Stor. e
?(Y Area Area Q10 Volume Surface SA W SA L Design Length Surface Depth (ft/ Base Base Volume Weir
TST _ or N) (Ac) (ac) - Cc (cfs) (CF) Area (sf) (ft) (ft) Width (ft) (ft) Area (sf) (ft) 1 ft) W(ft) L(ft) (cf) Length
SB-1 Y 8.61 _ 2.53 0.48 128.79 4,554.0 10,076.5 - 71.0 142.0 27.0 55.0 1,485.0 2.0 2 19.0 47.0 2,353.0 12
SB-2 Y 1.43 0.83 0.60 5.98 1,491.2 2,091.5 32.3 64.7 26.0 i 50.0 1,300.0 2.0 2 18.0 42.0 2,031.6 6 _
SB-3 Y 3.86 1.01 _ 0.45 12.11 1,813.1 4,236.9 46.0 92.1 26.0 50.0 1,300.0 2.0 2 18.0 42.0 2,031.6 10
SB-4 Y 0.89 0.21 0.60 3.72 375.1 1,301.9 25.5 51.0 26.0 50.0 1,300.0 2.0 2 18.0 42.0 2,031.6 4
SB-5 Y 0.93 0.44 0.60 3.89 796.7 1,360.7 26.1 ( 52.2 26.0 50.0 1,300.0 _ 2.0 2 18.0 42.0 2,031.6 4 1
Actual Volume:V=113h (G1 + ((G1xG2))A0.5) + G2) Where: G1 = base area, G2 = top area, h = depth
Required Volume= 3600 x Dist.Area (ac.)wlout Skimmer. 1,800 x Dist.Area wl Skimmer. •,••'� .ARO'••,,
Required Surface Area = DA " 350 (w/ skimmer) or DA" (450 w/out skimmer) .•••.� ,y'•.
Base Length = 2 x Base Width `�►
Drain Area Weir Lengths 5
(Acres) (Ft) _
1 4 '-`,Z0 ! ..,,'�' o ••.
4.00 3.3 3/g/Z¢
5.00 4.0
6.00 5.0
8.00 6.0

APPENDIX B
Temporary Sediment Basin Sizes - Design (CAD Calcs)
Highland Place Subdivision, Roxboro, NC
EROSION CONTROL
Req'd Req'd Re Dia Dia. Dia.
q q
Sediment Req'd. �d Surface Surface Base Base Top of Design (In.) (In.) (In.)
Top Top Berm Skimmer
TST Storage Surface Elevation Area Elevation Area Volume Head Orifice Orifice Orifice
SAW SA L Elevation Size
Volume Area (sf) (ft) (ft) MSL sq.ft. MSL sq.ft. MSL CF Size 1- Size 2- Size 3-
(CF) day days days
sa-i 4,554.0 10,076.5I 71.0 142.0 582.0 10,113.1 580.0 1448.9 584.0 11,562.0 3.0 2.0 3.2 2.3 1.9
SB-2 1,491.2 2,091.5 32.3 64.7 596.0 2,127.0 594.0 1388.3 ' 597.0 3,515.3 ' 1.5 1.5 ' 2.1 1.5 1.2 '
SB-3 1,813.1 4,236.9 46.0 92.1 586.0 4,322.5 ' 584.0 ' 3212.3 588.0 7,534.7 2.0 2.0 - 2.9 2.0 1.7
SB-4 375.1 1,301.9 25.5 51.0 593.0 1,491.7 592.0 1064.8 ' 594.0 1,278.2 1.5 1.5 - 1.3 0.9 - 0.7 '
Se 5 796.7 1,360.7 26.1 - 52.2 578.0 ' 1,362.5 576.0 688.4 580.0 2,050.9 r 1.5 1.5 1.6 1.1 0.9
Skimmer Head
Size (in.) (in.) �.•',,�1 CAR? •.,
1.50 1.5 cr C
2.00 2.0 i 2
3.00 3.0 S
4.00 3.3
5.00 4.0
6.00 5.0 ','•..`i'E' W.V+I,',,
8.00 6.0
3/e/L¢

Highland Place Subdivision APPENDIX C
Second Section - Erosion Control
Low Density Impervious Calculations
Total Site Area 1,099,159.47 25.23
Total Surface Water Area 3,781.44 0.09
Total Onsite Drainage Area 1,095,378.03 25.15
Total Offsite Drainage Area 980,956.88 22.52
Total Drainage Area 1,409,744.36 32.36
Total BUA in Project(23.99%) 262,781.19 6.03
Total Road Area in Project 76,860.19 1.76
Total Remaining BUA after Road
Construction 185,921.00 4.27
Total per Lot(64 Lots) 2,905.02
Stormwater Runoff Tc (Min) 110(in/hr) Cc Q10(cfs)
Pre-Construction 5 6.97 0.45 78.87
Post Construction 5 6.97 0.65 113.28
.,`• CA�� R''•.
e
r S •
w
••. EwVI
33g/ect

3/18/2024 HIGHLAND PLACE SUBDIVISION
PERMANENT DITCHLINE CALCULATIONS
APPENDIX D
street Grass/ Built CUU - UII(H 51A13Lt
Description DA Area Residential Woods Area Comp. Tc 110 PEAK SLOPE VEL. (YES/
DA(SF) (acres) (SF) Impervious(SF) (sf) Coef. Cc (Min.) (in/hr) (cfs) (ft./ft.) (fps) LINING NO) Notes
Ditch LC1 8,320.16 0.19 3,979 0 4,342 0.69 5 6.97 0.92 0.0180 1.05 Grass y
Ditch LC2 14,178.55 0.33 5,376 0 8,802 0.64 5 6.97 19.64 0.0284 3.96 Grass y LP4+LC6+LC6A+LC6B>LC2
Ditch LC3 76,648.13 1.76 4,867 0 71,781 0.48 5 6.97 5.91 0.0199 4.66 Grass y
Ditch LC4 28,991.00 0.67 2,414 11,532 15,045 0.69 5 6.97 4.66 0.0139 1.58 Grass y PP5>LC4
Ditch LC5 8,320.16 0.19 3,296 0 5,024 0.65 5 6.97 0.86 _ 0.0180 1.02 Grass y
Ditch LC6 43,184.07 0.99 1,441 0 41,743 0.47 5 6.97 4.37 0.0180 1.8 Grass y LP4>LC6
Ditch LC6A 97,210.84 _ 2.23 2,572 11,532 83,107 0.52 5 6.97 8.13 0.0180 2.23 Grass y
Ditch LC6B 49,609.42 1.14 3,568 8,649 37,392 _ 0.57 5 6.97 4.55 0.0200 2.38 Grass y
Ditch LC7 35558.79 0.82 2691.38 11532.00 21335.41 0.65 5.00 6.97 3.70 0.0284 1.80 Grass y
Ditch LC8 42,781.08 0.98 1,867 0 40,914 0.47 5 6.97 6.93 0.0199 2.24 Grass y LC7>LC8
Ditch LC9 8,326.14 0.19 2,495 2,883 2,948 0.77 5 6.97 1.03 0.0139 0.93 Grass y
Ditch PP1 7,744.47 0.18 4,210 0 3,535 0.72 5 6.97 0.89 _ 0.0197 1.09 Grass y
Ditch PP2 12,245.15 _ 0.28 5,016 2,883 4,346 0.77 5 6.97 1.51 _ 0.0347 1.83 Grass y
Ditch PP3 17,217.57 0.40 4,687 2,883 9,647 0.67 5 6.97 1.85 0.0091 0.89 Grass y
Ditch PP4 11,465.56 0.26 4,207 5,766 1,492 0.88 5 6.97 1.62 0.0197 1.34 Grass y
Ditch PP5 15,668.73 0.36 4,129 0 11,540 0.58 5 6.97 1.46 _ 0.0347 1.8 Grass y
Ditch PP6 8,271.68 0.19 2,871 0 5,401 0.62 5 6.97 0.83 0.0091 1.8 Grass y
Ditch LP1 11,182.55 0.26 4,689 0 6,493 0.66 5 6.97 1.18 0.0340 1.66 Grass y
Ditch LP2 5,520.03 0.13 1,540 2883 1,097 0.85 5 6.97 3.71 0.0200 1.81 Grass y LC5+LC1+LP1>LP2
Ditch LP3 10,862.79 0.25 2,101 0 8,762 0.55 5 6.97 0.95 0.0100 0.75 Grass y
J Ditch LP4 8,363.00 0.19 3,889 2883 1,591 0.85 5 6.97 1.14 0.0340 1.64 Grass y
Ditch LP5 114,874.45 2.64 1,379 8649 104,846 0.49 5 6.97 28.71 0.0200 3.68 Grass y LC2>LP5 """""•••
0•14Ditch LP6 51,594.46 1.18 2,274 11532 37,788 0.58 5 6.97 4.82 , 0.0100 1.32 Grass y . O i
Clear Water Diversion Ditches ? ..
I SEAL
Street Q10 DITCH STABLE 1819
Description ,`'E`%.9. °!!0!:"e.,0
DA Area Bare Comp. 110 PEAK SLOPE VEL. (YES/ ••• ,,4%. W.VI��;.•`�
DA(SF) (acres) (SF) Coef. Cc Tc (Min.) (in/hr) (cfs) (ft./ft.) (fps) LINING NO) Notes ••••••..•....`'.
CWD-1 195,119.53 4.48 0 0.95 5 6.97 29.66 0.0087 2.28 Bare Earth y 100% Imperv. 3/8/2024
CWD-2 174,269.66 4.00 0 0.95 5 6.97 26.49 0.0325 4.76 Bare Earth y 100% Imperv.

HIGHLAND PLACE SUBDIVISION APPENDIX E
DIVERSION DITCH CALCS
Street Bare Q10 DITCH STABLE
Description DA Area Comp. Tc 110 PEAK SLOPE VEL. (YES/
DA(SF) (acres) (SF) Coef. Cc (Min.) (in/hr) (cfs) (ft./ft.) (fps) LINING NO) Notes
Ditch LC1 8,320.16 0.19 3,979 0.45 5 6.97 0.60 0.0180 1.05 Bare Earth y
Ditch LC2 14,178.55 0.33 5,376 0.45 5 6.97 15.91 0.0284 4.19 Bare Earth y LP4+LC6+LC6A+LC6B>LC2
Ditch LC3 76,648.13 1.76 4,867 0.45 5 6.97 5.52 0.0199 4.66 Bare Earth y
Ditch LC4 28,991.00 0.67 2,414 0.45 5 6.97 3.22 0.0139 1.58 Bare Earth y PP5>LC4
Ditch LC5 8,320.16 0.19 3,296 0.45 5 6.97 0.60 0.0180 1.02 Bare Earth y
Ditch LC6 43,184.07 0.99 1,441 0.45 5 6.97 3.71 0.0180 1.26 Bare Earth y LP4>LC6
Ditch LC6A 97,210.84 2.23 2,572 0.45 5 6.97 7.00 0.0180 2.67 Bare Earth y
Ditch LC6B 49,609.42 1.14 3,568 0.45 5 6.97 3.57 0.0284 3.03 Bare Earth y
Ditch LC7 35,558.79 0.82 2,691 0.45 5 6.97 2.56 0.0199 2.11 Bare Earth y
Ditch LC8 42,781.08 0.98 1,867 0.45 5 6.97 5.64 0.0199 2.64 Bare Earth y LC7>LC8
Ditch LC9 8,326.14 0.19 2,495 0.45 5 6.97 0.60 0.0139 0.93 Bare Earth y
Ditch PP1 7,744.47 0.18 4,210 0.45 5 6.97 0.56 0.0197 1.09 Bare Earth y
Ditch PP2 12,245.15 0.28 5,016 0.45 5 6.97 0.88 0.0347 1.83 Bare Earth y
Ditch PP3 17,217.57 0.40 4,687 0.45 5 6.97 1.24 0.0091 0.89 Bare Earth y
Ditch PP4 11,465.56 0.26 4,207 0.45 5 6.97 0.83 0.0197 1.34 Bare Earth y
Ditch PP5 15,668.73 0.36 4,129 0.45 5 6.97 1.13 0.0347 1.8 Bare Earth y
Ditch PP6 8,271.68 0.19 2,871 0.45 5 6.97 0.60 0.0091 1.8 Bare Earth y
Ditch LP1 11,182.55 0.26 4,689 0.45 5 6.97 0.81 0.0340 1.66 Bare Earth y
Ditch LP2 5,520.03 0.13 1,540 0.45 5 6.97 2.40 0.0200 1.81 Bare Earth y LC5+LC1+LP1>LP2
Ditch LP3 10,862.79 0.25 2,101 0.45 5 6.97 0.78 0.0100 0.75 Bare Earth y
Ditch LP4 8,363.00 0.19 3,889 0.45 5 6.97 0.60 0.0340 1.64 Bare Earth y
Ditch LP5 114,874.45 2.64 1,379 0.45 5 6.97 24.18 0.0200 3.98 Bare Earth y LC2>LP5
Ditch LP6 51,594.46 1.18 2,274 0.45 5 6.97 3.72 0.0100 1.32 Bare Earth y
Rpl
il r41-S
44,
• SE w.� 40`1
3/gk4

HIGHLAND PLACE SUBDIVISION APPENDIX F
CULVERT SIZING
Homes:
Imperv.
Area in WS
Contrib. Contrib. (2,883 SF Pave. Area Pipe Pipe Pipe Top Depth
Culvert Drainage Drainage Homes Max./ In WS Intensity Q10 Dia. Inv. Length Slope Top of Pave in Pipe Vel.
No. Area (SF) Area (AC) in WS Home) (SF) Cc I10 (in/hr) (cfs) (in) Inv. In Out (ft) (ft/ft) Pipe Elev. (in) (ft/sec)
C-1 21,574.63 0.50 0 0 7,984.84 0.64 6.97 _ 2.19 18 ' 594.50 594.00 48 0.0104 596.00 596.89 0.46 4.76
-
C-2 145,596.09 3.34 7 20,181 6,139.46 0.54 6.97 12.59 24 591.50�590.00 61 0.0246 593.00 594.64 0.82 10.33 LP-6 & 6A
C-3 119,776.22 2.75 7 20,181 11,439.87 0.58 6.97 11.15 18 593.50 591.50 69 0.0290 594.25 595.28 0.86 10.67
C-4 38,128.85 0.88 5 14,415 4,207.41 0.69 6.97 _ 4.24 18 599.50 597.00 76 0.0329 600.00 605.39 0.48 8.68
C-5 327,373.09 7.52 21 60,543 23,920.12_ 0.58 6.97 30.33 30 _588.00 584.00 88 0.0455 588.75 594.08 1.08 16.71 36" Design
C-6 26,189.30 0.60 0 0 4,687.46 0.54 6.97 2.26 18 582.00 578.00 70 0.0571 581.75 585.24 0.3 8.81
Rip Rap Aprons p ,R •.
4. cfESSi.' '�
i.
Min. D50 SEAL
Q10 Depth Q10 Full Flow Min. Apron Stone Apron 181 . i'
Discharge Pipe Dia. of Flow Velocity Capacity Apron Width Size Depth e,
Culvert (CFS) (in) (in) (fps) (CFS) Length (ft) (ft) (in) (in) �•••'srE W.`H��;.�...
C 1 2.19 18 0.46 4.76 10.71 10 12 6 14 /q/ �
C-2 12.59 24 0.82 10.33 35.48 14 16 6 14 D
C-3 11.15 18 0.86 10.67 17.89 10 12 6 14
C-4 4.24 18 0.48 8.68 19.05 14 16 6 14
C-5 30.33 30 1.08 16.71 87.49 20 23 6 14
C-6 2.26 18 0.3 8.81 25.1 10 12 6 14