SW6221203_Stormwater Report_20221220

DocuSign Envelope ID: EED559AA-362B-49FO-A4FE-OAC530947B9D
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TIMMONS GROUP
YOUR VISION ACHIEVED THROUGH OURS.
Date: November 4, 2022 1
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Subdivision Name: Briarwood Park N
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Location: Rosser Pittman Road
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Developer: Weaver Development Company
350 Wagoner Drive, Suite 100 N
Fayetteville, NC 28030 0
Phone: [phone]
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Consultant: Timmons Group
5410 Trinity Road, Suite 102
Raleigh, NC 27607
Phone [phone] L
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Preliminary Stormwater Statement Ln
Briarwood Park is a proposed single-family detached community comprising of 8
residential lots on 7.89 acres located on Rosser Pittman Road in Harnett County.
The site is zoned RA-20R and will be served by Harnett County public water and
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individual septic systems.
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A maximum of 3,800 square feet of impervious area is proposed per lot with a total
proposed impervious area of 1.20 acres (15.2%). Because the total proposed
impervious area is below 24%, the site will not require peak attenuation.
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Stormwater will be conveyed with the use of ditches and crossing pipes. All
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stormwater and erosion control design shall comply with Harnett County, the
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NCDEQ Stormwater Design Manual, and the NCDEQ Erosion and Sediment
Control Planning and Design Manual.
10 Year 25 Year
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Pre -Development 13.54 cfs 15.01 cfs
Post Development 21.98 cfs 24.36 cfs OD42ADF BB46B
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DocuSign Envelope ID: EED559AA-362B-49FO-A4FE-OAC530947B9D
TIMMONS GROUP
YOUR VISION ACHIEVED THROUGH OURS.
BRIARWOOD PARK
VICINITY MAP

DocuSign Envelope ID: EED559AA-362B-49FO-A4FE-OAC530947B9D
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2019

DocuSign Envelope ID: EED559AA-362B-49FO-A4FE-OAC530947B9D
Hydrologic Soil Group —Harnett County, North Carolina
(WSS)
677210 677240 677270 6773M 677330 6773M 677390 677420
35o 21' 33" N
9
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35o 21' 26" N
677210 677240 677270 677300 677330 677360 677390
Map Scale: 1:1,550 if printed on A landscape (11" x 8.5") sheet.
Meters N
0 20 40 80 120
Feet
0 50 100 200 300
Map projection: Web Mercator Conermordinates: WGS84 Edge tics: UTM Zone 17N WGS84
USDA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
677450 677480 677510
677420 677450 6774M 677510
a
677540
35o 21' 33" N
d_
35o 21' 26" N
677540
in
11 /16/2021
Pagel of 4

DocuSign Envelope ID: EED559AA-362B-49FO-A4FE-OAC530947B9D
Hydrologic Soil Group —Harnett County, North Carolina
(WSS)
MAP LEGEND
Area of Interest (AOI)
0
Area of Interest (AOI)
Soils
Soil Rating
Polygons
0
A
0
A/D
0
B
0
B/D
C
0
C/D
0
D
0
Not rated or not available
Soil Rating
Lines
r 0
A
r 0
A/D
B
B/D
N 0
C
r 0
C/D
r 0
D
r 0
Not rated or not available
Soil Rating
Points
0
A
0
A/D
■
B
S
B/D
❑ C
0 C/D
0 D
❑ Not rated or not available
Water Features
Streams and Canals
Transportation
— Rails
­0 Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
MAP INFORMATION
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Harnett County, North Carolina
Survey Area Data: Version 18, Sep 1, 2021
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jul 28, 2019—Jul 30,
2019
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
usoA Natural Resources Web Soil Survey 11/16/2021
Conservation Service National Cooperative Soil Survey Page 2 of 4

DocuSign Envelope ID: EED559AA-362B-49FO-A4FE-OAC530947B9D
Hydrologic Soil Group —Harnett County, North Carolina
NW-19
Hydrologic Soil Group
Map unit symbol
Map unit name
Rating
Acres in AOI
Percent of AOI
Bb
Bibb soils, frequently
flooded
A/D
0.0
0.5%
DoA
Dothan loamy sand, 0 to
2 percent slopes
B
0.7
8.3%
NeD
Nason silt loam, 8 to 15
percent slopes
B
0.7
8.3%
NoB
Norfolk loamy sand, 2 to
6 percent slopes
A
6.5
82.8%
Totals for Area of Interest
7.9
100.0%
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long -duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink -swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
USDA Natural Resources Web Soil Survey 11/16/2021
Conservation Service National Cooperative Soil Survey Page 3 of 4

DocuSign Envelope ID: EED559AA-362B-49FO-A4FE-OAC530947B9D
Hydrologic Soil Group —Harnett County, North Carolina
AMI-19
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff.- None Specified
Tie -break Rule: Higher
USDA Natural Resources Web Soil Survey 11/16/2021
Conservation Service National Cooperative Soil Survey Page 4 of 4

DocuSign Envelope ID: EED559AA-362B-49FO-A4FE-OAC530947B9D
Project:
Briarwood Park
Project Number: TIMMONS GROUP
48550 YOUR VISION ACHIEVED THROUGH OURS.
PRE -DEVELOPMENT Rational Method Worksheet
Calculated By:
Ryan Wadsworth
Date:
1 /28/2022
SITE C VALUE CALCULATIONS
Category
C;
A;
C;x A;
Roof & Pavement
0.95
0.09
0.09
Meadow/Pasture Land Area
0.25
1.48
0.37
Wooded Area
0.20
6.31
1.26
Open Water
1.00
0.01
0.01
7.89
1.73
C Value
0.22
SITE PEAK FLOW CALCULATIONS
1-Year
10-Year
25-Yea r
C-Value
0.22
0.22
0.22
Intensity in/hr
5.18
7.85
8.70
Area AC
7.89
7.89
7.89
Peak Flow cfs
8.94
13.54
15.01

DocuSign Envelope ID: EED559AA-362B-49FO-A4FE-OAC530947B9D
.0
Project:
Briarwood Park
Project Number: T I M M O N S GROUP
48550 YOUR VISION ACHIEVED THROUGH OURS.
POST -DEVELOPMENT Rational Method Worksheet
Calculated By:
Ryan Wadsworth
Date:
1 /28/2022
SITE C VALUE CALCULATIONS
Category
C;
A;
C; x A;
Roof & Pavement
0.95
1.35
1.28
Unimproved Areas
0.35
1.40
0.49
Wooded Area
0.20
5.14
1.03
Open Water
1.00
0.00
0.00
7.89
2.80
C Value
0.35
SITE PEAK FLOW CALCULATIONS
1-Year
10-Year
25-Year
C-Value
0.35
0.35
0.35
Intensity in/hr
5.18
7.85
8.70
Area AC
7.89
7.89
7.89
Peak Flow cfs
14.50
21.98
24.36

DocuSign Envelope ID: EED559AA-362B-49FO-A4FE-OAC530947B9D
PERMANENT CHANNEL SCHEDULE
(Chapter 8.05 of the NCDEQ E&SC Planning and Design Manual)
LENGTH
DA
ACCUM.
Igo
Quo
SLOPE
V
SHEAR
FLOW
FLOW
Wp
R
SWALE
SIDE
PERMANENT
NAME
DA
C
N VALUE
DEPTH
AREA
DEPTH
SLOPE
LINING
(FT)
(AC)
(AC)
(INIHR)
(CFS)
(%)
(FTIS)
(PSF)
(FT)
(FT-2)
(FT)
(FT)
(IN)
(H:V)
DITCH 1
916
1.77
0.50
7.85
6.95
1.90%
0.037
3.07
1.03
0.87
2.27
5.50
0.41
24
3:1
GRASS
DITCH 2
884
0.59
0.50
7.85
2.31
1.90%
0.040
2.16
0.69
0.58
1.01
3.67
0.27
24
3:1
GRASS