SW6221006_Stormwater Narrative_20221025

Stormwater Narrative and Calculations for the
NCDEMLR Post Construction Stormwater Management
Permit
for the
+/- 20,000-SF Distribution Facility Expansion for
CCBCC- Fayetteville
in
Cumberland County, North Carolina
Prepared For:
CCBCC Operations, LLC
)F
&ra�—
CONSOLIDATED
Prepared By:
Fitts and Goodwin, Inc.
120 Corporate Blvd.
West Columbia, SC 29169
NC License 051479
Initial Submittal: 09/27/2022

Table of Contents
Narrative....................................................................................................................................................... 2
SiteMaps......................................................................................................................................................
3
Drainage Area and Runoff Calculations......................................................................................................
15
Wet Detention Pond Volume Calculations.................................................................................................
17
DrawdownCalculations..............................................................................................................................21
Rip -Rap Sizing Calculations.........................................................................................................................23
CCBCC Fayetteville 1 September 2022

Narrative
These calculations have been prepared to address NCDEMLR's post -construction
stormwater management requirements for the +/- 20,000-SF Distribution Facility
Expansion for CCBCC-Fayetteville. The site is located at 800 Tom Starling Rd.
Fayetteville, NC (34057'8.21 "N, 78053'37.76"W) which is an unincorporated area of
Cumberland County.
The current site totals +/- 13.7-acres and includes +/- 6.75-acres of existing built -upon
area (BUA). The existing BUA consists of a +/- 45,000-sf warehouse and a +/- 6,500-sf
maintenance facility with the remainder being parking and truck court space.
Stormwater runoff from this existing BUA is conveyed through a pipe network to an
existing wet detention pond located in the northwest quadrant of the site. The remaining
areas of the site are grassed, landscaped, and wooded and runoff from these areas
bypasses the existing detention pond.
The proposed development of the site will include a +/- 20,000-sf expansion to the
existing warehouse and expansion of the existing truck court which will result in a net
increase of +/- 0.73-ac of impervious area. The total proposed drainage area will be +/-
8.07-ac consisting of +/- 6.75-ac of existing BUA, +/- 0.73-ac of new BUA, and +/- 0.59-
ac of grassed area. The proposed drainage pattern will remain consistent with the
existing pattern and runoff from the new impervious area will be conveyed to the
existing wet detention pond through the existing pipe network. The existing pond will be
modified as required to meet current standards as shown within these calculations.
The USGS Soil Survey indicates the site consists of Torhunta (HSG A/D) and Kalmia
(HSG B) soils. FEMA Flood Panel 3720043300J indicates the site is located in Zone X —
Area of Minimal Flood Hazard.
CCBCC Fayetteville 2 September 2022

Site Maps
CCBCC Fayetteville 3 September 2022

"Of US Topo
Abdnd
HOPE MILLS QUADRANGLE
NORTH CAROLINA
7.5-MINUTE SERIES
-78.875(
88 89 90 91 92 93

National Flood Hazard Layer FI RMette
78o53'50"W 34o57'23"N
j
f,
i t
ERL:A-TD COW
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070`��
OFf1111+1'FILOD R
FEMA
40
F
IL
IP
Approximate Site
Boundary �
i
IK
Feet 1:61000 78o53'13"W 34o56'53"N
0 250 500 1,000 1,500 2,000
Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020
Legend
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
Without Base Flood Elevation (BFE)
Zone A, V, A99
SPECIAL FLOOD Wit
hBFE orDepthZoneAE,AO,AH,Ve,Aa
HAZARD AREAS Regulatory Floodway
0.2% Annual Chance Flood Hazard, Areas
of 1% annual chance flood with average
depth less than one foot or with drainage
areas of less than one square mile Zonex
Future Conditions 1% Annual
4 '- Chance Flood Hazard Zonex
" Area with Reduced Flood Risk due to
OTHER AREAS OF Levee. See Notes. zone
FLOOD HAZARD " Area with Flood Risk due to Leveezone D
NO SCREEN Area of Minimal Flood Hazard
Q Effective LOMRs
OTHER AREAS Area of Undetermined Flood Hazard
GENERAL - — - - Channel, Culvert, or Storm Sewer
STRUCTURES i i i i i i i Levee, Dike, or Floodwall
e zo.z Cross Sections with 1% Annual Chance
17,5 Water Surface Elevation
a - - - Coastal Transect
—sfa— Base Flood Elevation Line (BFE)
Limit of Study
Jurisdiction Boundary
— --- Coastal Transect Baseline
OTHER _ Profile Baseline
FEATURES Hydrographic Feature
❑ Digital Data Available AN
0 No Digital Data Available
MAP PANELS El Unmapped
QThe pin displayed on the map is an approximate
point selected by the user and does not represent
an authoritative property location.
This map complies with FEMA's standards for the use of
digital flood maps if it is not void as described below.
The basemap shown complies with FEMA's basemap
accuracy standards
The flood hazard information is derived directly from the
authoritative NFHL web services provided by FEMA. This map
was exported on 8/31/2022 at 8:39 AM and does not
reflect changes or amendments subsequent to this date and
time. The NFHL and effective information may change or
become superseded by new data overtime.
This map image is void if the one or more of the following map
elements do not appear: basemap imagery, flood zone labels,
legend, scale bar, map creation date, community identifiers,
FIRM panel number, and FIRM effective date. Map images for
unmapped and unmodernized areas cannot be used for
regulatory purposes.

Soil Map —Cumberland County, North Carolina
691300 691500 691700 691900 692100 692300 692500 692700 692900 693100 693300
34o 5731" N
r
�i
g
0
r
�i
g
r
8
34o 56'36"N
691300 691500 691700 691900 692100 692300 692500
Map Scale: 1:11,900 if printed on A landscape (11" x 8.5") sheet.
Meters
N 0 150 300 E00 900
Feet
0 500 1000 2000 3000
Map projection: Web Mercator Conermordinates: WGS84 Edge tics: lfrM Zone 17N WGS84
usoA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
692700 692900 693100 6933M
6935M 693700
34o 5731" N
r
�i
r
�i
g
0
r
�i
g
34o 56' 36" N
693500 693700
a
8/31/2022
Page 1 of 3

MAP LEGEND
Area of Interest (AOI)
0
Area of Interest (AOI)
Soils
0
Soil Map Unit Polygons
,N
Soil Map Unit Lines
Soil Map Unit Points
Special
Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
�i
Gravelly Spot
0
Landfill
A.
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
o
Sodic Spot
Soil Map —Cumberland County, North Carolina
MAP INFORMATION
Spoil Area
The soil surveys that comprise your AOI were mapped at
1:24,000.
Stony Spot
Very Stony Spot
Warning: Soil Map may not be valid at this scale.
Wet Spot
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
4�
Other
line placement. The maps do not show the small areas of
Special Line Features
contrasting soils that could have been shown at a more detailed
scale.
Water Features
Streams and Canals
Please rely on the bar scale on each map sheet for map
measurements.
Transportation
Rails
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
. 0
Interstate Highways
Coordinate System: Web Mercator (EPSG:3857)
US Routes
Maps from the Web Soil Survey are based on the Web Mercator
Major Roads
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Local Roads
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
Background
Aerial Photography
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Cumberland County, North Carolina
Survey Area Data: Version 23, Jan 21, 2022
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Apr 11, 2022—May
15, 2022
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 8/31/2022
Conservation Service National Cooperative Soil Survey Page 2 of 3

Soil Map -Cumberland County, North Carolina
Map Unit Legend
Map Unit Symbol
Map Unit Name
Acres in AOI
Percent of AOI
BaD
Blaney loamy sand, 8 to 15
percent slopes
2.3
0.4%
GdB
Gilead loamy sand, 2 to 8
percent slopes
47.2
7.4%
GoA
Goldsboro loamy sand, 0 to 2
percent slopes, Southern
Coastal Plain
5.0
0.8%
JT
Johnston loam
30.5
4.8%
KaA
Kalmia loamy sand, 0 to 2
percent slopes
69.8
11.0%
KeA
Kenansville loamy sand, 0 to 3
percent slopes
178.5
28.0%
LaB
Lakeland sand, 1 to 8 percent
slopes
13.2
2.1 %
Le
Leon sand
26.5
4.2%
Pa
Pactolus loamy sand
7.7
1.2%
Pg
Pantego loam
8.7
1.4%
Ra
Rains sandy loam, 0 to 2
percent slopes
9.7
1.5%
TaB
Tarboro loamy sand, 0 to 6
percent slopes
3.5
0.5%
TR
Torhunta and Lynn Haven soils
223.2
35.0%
Ud
Udorthents, loamy
1.8
0.3%
VaD
Vaucluse loamy sand, 8 to 15
percent slopes
7.5
1.2%
VgE
Vaucluse-Gilead loamy sands,
15 to 25 percent slopes
1.8
0.3%
Totals for Area of Interest
637.0
100.0%
USDA Natural Resources Web Soil Survey 8/31/2022
Conservation Service National Cooperative Soil Survey Page 3 of 3

Engineering Properties ---Cumberland County, North Carolina
Engineering Properties
This table gives the engineering classifications and the range of engineering
properties for the layers of each soil in the survey area.
Hydrologic soil group is a group of soils having similar runoff potential under
similar storm and cover conditions. The criteria for determining Hydrologic soil
group is found in the National Engineering Handbook, Chapter 7 issued May
2007(http://directives.sc.egov.usda.gov/OpenNonWebContent.aspx?
content=17757.wba). Listing HSGs by soil map unit component and not by soil
series is a new concept for the engineers. Past engineering references contained
lists of HSGs by soil series. Soil series are continually being defined and
redefined, and the list of soil series names changes so frequently as to make the
task of maintaining a single national list virtually impossible. Therefore, the
criteria is now used to calculate the HSG using the component soil properties
and no such national series lists will be maintained. All such references are
obsolete and their use should be discontinued. Soil properties that influence
runoff potential are those that influence the minimum rate of infiltration for a bare
soil after prolonged wetting and when not frozen. These properties are depth to a
seasonal high water table, saturated hydraulic conductivity after prolonged
wetting, and depth to a layer with a very slow water transmission rate. Changes
in soil properties caused by land management or climate changes also cause the
hydrologic soil group to change. The influence of ground cover is treated
independently. There are four hydrologic soil groups, A, B, C, and D, and three
dual groups, A/D, B/D, and C/D. In the dual groups, the first letter is for drained
areas and the second letter is for undrained areas.
The four hydrologic soil groups are described in the following paragraphs:
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.
Depth to the upper and lower boundaries of each layer is indicated.
USDA Natural Resources Web Soil Survey 8/17/2022
Conservation Service National Cooperative Soil Survey Page 1 of 6

Engineering Properties ---Cumberland County, North Carolina
Texture is given in the standard terms used by the U.S. Department of
Agriculture. These terms are defined according to percentages of sand, silt, and
clay in the fraction of the soil that is less than 2 millimeters in diameter. "Loam,"
for example, is soil that is 7 to 27 percent clay, 28 to 50 percent silt, and less than
52 percent sand. If the content of particles coarser than sand is 15 percent or
more, an appropriate modifier is added, for example, "gravelly."
Classification of the soils is determined according to the Unified soil classification
system (ASTM, 2005) and the system adopted by the American Association of
State Highway and Transportation Officials (AASHTO, 2004).
The Unified system classifies soils according to properties that affect their use as
construction material. Soils are classified according to particle -size distribution of
the fraction less than 3 inches in diameter and according to plasticity index, liquid
limit, and organic matter content. Sandy and gravelly soils are identified as GW,
GP, GM, GC, SW, SP, SM, and SC; silty and clayey soils as ML, CL, OL, MH,
CH, and OH; and highly organic soils as PT. Soils exhibiting engineering
properties of two groups can have a dual classification, for example, CL-ML.
The AASHTO system classifies soils according to those properties that affect
roadway construction and maintenance. In this system, the fraction of a mineral
soil that is less than 3 inches in diameter is classified in one of seven groups
from A-1 through A-7 on the basis of particle -size distribution, liquid limit, and
plasticity index. Soils in group A-1 are coarse grained and low in content of fines
(silt and clay). At the other extreme, soils in group A-7 are fine grained. Highly
organic soils are classified in group A-8 on the basis of visual inspection.
If laboratory data are available, the A-1, A-2, and A-7 groups are further
classified as A-1-a, A-1-b, A-2-4, A-2-5, A-2-6, A-2-7, A-7-5, orA-7-6. As an
additional refinement, the suitability of a soil as subgrade material can be
indicated by a group index number. Group index numbers range from 0 for the
best subgrade material to 20 or higher for the poorest.
Percentage of rock fragments larger than 10 inches in diameter and 3 to 10
inches in diameter are indicated as a percentage of the total soil on a dry -weight
basis. The percentages are estimates determined mainly by converting volume
percentage in the field to weight percentage. Three values are provided to
identify the expected Low (L), Representative Value (R), and High (H).
Percentage (of soil particles) passing designated sieves is the percentage of the
soil fraction less than 3 inches in diameter based on an ovendry weight. The
sieves, numbers 4, 10, 40, and 200 (USA Standard Series), have openings of
4.76, 2.00, 0.420, and 0.074 millimeters, respectively. Estimates are based on
laboratory tests of soils sampled in the survey area and in nearby areas and on
estimates made in the field. Three values are provided to identify the expected
Low (L), Representative Value (R), and High (H).
Liquid limit and plasticity index (Atterberg limits) indicate the plasticity
characteristics of a soil. The estimates are based on test data from the survey
area or from nearby areas and on field examination. Three values are provided to
identify the expected Low (L), Representative Value (R), and High (H).
References:
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of
sampling and testing. 24th edition.
USDA Natural Resources Web Soil Survey 8/17/2022
Conservation Service National Cooperative Soil Survey Page 2 of 6

Engineering Properties ---Cumberland County, North Carolina
American Society for Testing and Materials (ASTM). 2005. Standard
classification of soils for engineering purposes. ASTM Standard D2487-00.
USDA Natural Resources Web Soil Survey 8/17/2022
Conservation Service National Cooperative Soil Survey Page 3 of 6

Engineering Properties ---Cumberland County, North Carolina
Report —Engineering Properties
Absence of an entry indicates that the data were not estimated. The asterisk'*' denotes the representative texture; other
possible textures follow the dash. The criteria for determining the hydrologic soil group for individual soil components is
found in the National Engineering Handbook, Chapter 7 issued May 2007(http://directives.sc.egov.usda.gov/
Open NonWebContent. aspx?content= 1 7757.wba). Three values are provided to identify the expected Low (L),
Representative Value (R), and High (H).
Engineering Properties —Cumberland County, North Carolina
Map unit symbol and
Pct. of
Hydrolo
Depth
USDA texture
Classification
Pct Fragments
Percentage passing sieve number—
Liquid
Plasticit
soil name
map
gic
limit
y index
unit
group
Unified
AASHTO
>10
3-10
4
10
40
200
inches
inches
In
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
KaA—Kalmia loamy
sand, 0 to 2 percent
slopes
Kalmia
85
B
0-8
Loamy sand, loamy
SC-SM,
A-2-4
0-0-0
0-0-0
92-100-
92-100-
64-82-
9-22- 25
9-12 -14
NP
fine sand
SM
100
100
85
8-12
Loamy sand, loamy
SC-SM,
A-2-4, A-4
0-0-0
0-0-0
76-96-1
75-96-1
55-76-
19-29-
9-12 -14
NP
fine sand, sandy
SM
00
00
89
40
loam, fine sandy
loam
12-32
Sandy clay loam,
SC-SM,
A-2-4,
0-0-0
0-0-0
76-96-1
75-96-1
45-82-
19-48-
7-25 -45
NP-9
sandy loam, loam,
CL, ML,
A-4,
00
00
96
60
-18
fine sandy loam
SC, SM
A-6,
A-7-6
32-80
Sand, fine sand,
SP-SM,
A-2-4
0-0-0
0-0-0
77-97-1
76-97-1
53-79-
8-21- 25
9-12 -14
NP
loamy sand,
SM
00
00
85
loamy fine sand
USDA Natural Resources Web Soil Survey 8/17/2022
Conservation Service National Cooperative Soil Survey Page 4 of 6

Engineering Properties ---Cumberland County, North Carolina
Engineering Properties —Cumberland County, North Carolina
Map unit symbol and
Pct. of
Hydrolo
Depth
USDA texture
Classification
Pct Fragments
Percentage passing sieve number—
Liquid
Plasticit
soil name
map
gic
limit
y index
unit
group
Unified
AASHTO
>10
3-10
4
10
40
200
inches
inches
In
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
KeA—Kenansville
loamy sand, 0 to 3
percent slopes
Kenansville
90
A
0-8
Fine sand, loamy
SM
A-2-4
0-0-0
0-0-0
100-100
95-97-1
73-77-
18-22-
9-12 -14
NP
sand
-100
00
84
26
8-24
Fine sand, loamy
SM
A-2-4
0-0-0
0-0-0
100-100
95-97-1
73-77-
18-22-
9-12 -14
NP
sand
-100
00
84
26
24-36
Sandy clay loam,
SC-SM,
A-2-4,
0-0-0
0-0-0
100-100
94-96-1
68-75-
32-39-
16-23
2-7-14
sandy loam, fine
SC, SM
A-4, A-6
-100
00
88
50
-32
sandy loam
36-42
Sandy loam, fine
SC-SM,
A-2-4
0-0-0
0-0-0
100-100
94-96-1
71-77-
18-23-
0-19 -27
NP-4
sandy loam,
SM
-100
00
88
32
-10
loamy sand, sand
42-84
Sand, loamy sand,
SP-SM,
A-2-4
0-0-0
0-0-0
100-100
95-97-1
70-75-
6-11- 16
6-10 -13
NP
loamy fine sand
SM
-100
00
82
USDA Natural Resources Web Soil Survey 8/17/2022
Conservation Service National Cooperative Soil Survey Page 5 of 6

Engineering Properties ---Cumberland County, North Carolina
Engineering Properties —Cumberland County, North Carolina
Map unit symbol and
Pct. of
Hydrolo
Depth
USDA texture
Classification
Pct Fragments
Percentage passing sieve number—
Liquid
Plasticit
soil name
map
gic
limit
y index
unit
group
Unified
AASHTO
>10
3-10
4
10
40
200
inches
inches
In
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
L-R-H
TR—Torhunta and
Lynn Haven soils
Lynn haven,
41
A/D
0-9
Sand
SP-SM,
A-2-4, A-3
0- 0- 0
0-0-0
100-100
100-100
75-77-
7- 9- 12
6-10-13
NP
undrained
SP
-100
-100
80
9-12
Sand, fine sand
SP-SM,
A-2-4, A-3
0- 0- 0
0-0-0
100-100
100-100
75-77-
6-7-9
6-10 -13
NP
SM, SP
-100
-100
78
12-80
Sand, fine sand,
SC-SM,
A-2-4, A-3
0- 0- 0
0-0-0
100-100
100-100
74-77-
7-10-13
6-10 -13
NP
loamy sand
SM
-100
-100
80
Torhunta, undrained
39
A/D
0-15
Loam, loamy fine
SC-SM,
A-2-4, A-4
0- 0- 0
0-0-0
100-100
95-96-1
80-88-
34-41-
15-20
NP-2 -4
sand, fine sandy
SM
-100
00
98
49
-25
loam, loamy sand
15-40
Sandy loam, fine
SC-SM,
A-2-4, A-4
0- 0- 0
0-0-0
100-100
95-96-1
80-88-
34-41-
15-20
NP-4 -7
sandy loam
SM
-100
00
98
49
-25
40-80
Loamy sand, sand,
SC-SM,
A-2-4, A-3
0- 0- 0
0-0-0
100-100
95-97-1
69-78-
17-25-
9-12 -14
NP
sandy loam
SP-SM,
-100
00
89
34
SM
Torhunta, drained
10
A/D
0-15
Loam, loamy fine
SC-SM,
A-2-4, A-4
0- 0- 0
0-0-0
100-100
95-96-1
80-88-
34-41-
15-20
NP-2 -4
sand, fine sandy
SM
-100
00
98
49
-25
loam, loamy sand
15-40
Sandy loam, fine
SC-SM,
A-2-4, A-4
0- 0- 0
0-0-0
100-100
95-96-1
80-88-
34-41-
15-20
NP-4 -7
sandy loam
SM
-100
00
98
49
-25
40-80
Loamy sand, sand,
SC-SM,
A-2-4, A-3
0- 0- 0
0-0-0
100-100
95-97-1
69-78-
17-25-
9-12 -14
NP
sandy loam
SP-SM,
-100
00
89
34
SM
Data Source Information
Soil Survey Area: Cumberland County, North Carolina
Survey Area Data: Version 23, Jan 21, 2022
USDA Natural Resources Web Soil Survey 8/17/2022
Conservation Service National Cooperative Soil Survey Page 6 of 6

Drainage Area and Runoff Calculations
CCBCC Fayetteville 15 September 2022

Drainage Area and Runoff Calculations
for
+/-20,000-SF Distribution Facility Expansion for CCBCC-Fayetteville
Drainage Area:
Runoff Calculation Method
Drainage Area Characteristics
Total Drainage Area to Basin =
New Impervious Area =
Impervious Ratio =
Design Storm Depth =
Simple Method for Runoff Volume
Post -Development Drainage Area 1
Simple
8.07 ac
0.73 ac
9.0
1.0 in
Rv = 0.05 + 0.9 * I,,
Where: Rv = Runoff cjc eAcient (unitless)
IA = Impervious fraction (unittess)
DV = 3630 " RD' Rv " A
Where: DV = Design volume (tuft)
R❑ = Design storm depth (in)
A = Drainage area (ac)
la = 0.09
Rv = 0.13
Rd = 1.0
A = 8.07
DV = 3,850
Minimum Tempoary Storage Volume Required = 3,850
Temporary Storage Volume Provided = 47,195
cu ft
cu ft
Project No.: 22000-0600
Date: September 2022

Wet Detention Pond Volume Calculations
CCBCC Fayetteville 17 September 2022

Wet Pond Volumes
for
+/-20,000-SF Distribution Facility Expansion for CCBCC-Fayetteville
Basin: Modified Existing Wet Pond
Basin Elevations
Forebay Bottom =
87 ft
Forebay Top =
90.63 ft
Main Pool Bottom=
86 ft
Normal Pool =
90.63 ft
Vegetated Shelf Bot. =
90.13 ft
Vegetated Shelf Top =
91.13 ft
Temporary Pool Elevation =
93.63 ft
Top of Pond =
96 ft
Forebay Volume
Contour Elevation (ft)
Area (sf)
Inc. Vol. (cf)
Accum. Vol. (cf)
87
447
0
0
88
807
627
627
89
1250
1029
1656
90
1 1769
1 1510
1 3166
90.63
1 2252
1 1266
1 4433
Main Pool Volume
Contour Elevation (ft)
Area (sf)
Inc. Vol. (cf)
Accum. Vol. (cf)
86
2933
0
0
87
4218
3575
3575
88
5570
4894
8470
89
6987
6279
14749
90
8470
7728
22478
90.63
10223
5888
28367
Temporary Pool Volume
Contour Elevation (ft)
Area (sf)
Inc. Vol. (cf)
Accum. Vol. (cf)
90.63
10223
0
0
91
14158
4510
4510
92
15491
14824
19335
93
17050
16270
35606
94
18492
17771
53377
95
19671
19082
72460
96
21027
20349
92809
Forebay Volume = 4433
= 15.63
Main Pool Volume = 28367
Forebay is 15-20% of main pool volume
Project No.: 22000-0600
Date: September 2022

Wet Pond Volumes
for
+/-20,000-SF Distribution Facility Expansion for CCBCC-Fayetteville
Basin:
Volume Calculation Method
Basin Elevations
Forebay Bottom =
Forebay Top =
Main Pool Bottom=
Normal Pool =
Vegetated Shelf Bot. _
Vegetated Shelf Top =
Temporary Pool Elevation =
Top of Pond =
HRT Method for Main Pool Volume
Modified Existing Wet Pond
Hydraulic Retention Time (HRT) Method
87 ft
90.63 ft
86 ft
90.63 ft
90.13 ft
91.13 ft
93.63 ft
96 ft
Vmp = 0.87 * T TT * DV
r,
Where: 9.87 = Factor to adjust for the volume in the forebay
VMP = Main pool volume, not including the forebay (cubic feet)
HRT = Required hydraulic residence time (14 days)
Ts = Average time between storm events {5 days)
DV = ❑esign volume (cubic feet)
DV = 3,850
Vmp = 9,379
Minimum Main Pool Volume Required = 9,379 cu ft
Main Pool Volume Provided = 28,367 cu ft
Average Depth Calculation:
Option 1:
VPP
❑avg =
A
Where: Daao = Average depth (feet)
VPP = Main pool volume at permanent pool elevation (feeP)
SA = Main pool area at permanent pool elevation (feet2)
Vpp = 28,367
SA = 10,223
Davg = 2.77
Minimum Average Depth Required = 3 ft
Average Depth Provided = 2.77 ft
See Design Option 2
Project No.: 22000-0600
Date: September 2022

Wet Pond Volumes
for
+/-20,000-SF Distribution Facility Expansion for CCBCC-Fayetteville
Option 2:
VPP—Vshe}
Davg =
Ab:—o:r.:t naelr
Where:
Dav- =
Average depth (feet)
VPP =
Main pool volume at pemtianent pool elevation {feeP)
Vsheir =
Volume over the shelf only (feeiP) — see below
Awouraraneir =
Area of main pool at the bottom of the shelf Jeet2)
vtow =
0.5 " ❑e pth.. averwm ` Perimeterp.,rm pad " W idthewrmMw part orawr
Where:
Depth.
Dept of water at the deep side of the shelf as
measured from the permanent pool (feet)
Perimeters,,,
Perimeter of main pool at the bottom of the
shelf (fee[)
Widthsu upatara,erc
= Width from the deep side tD the dry side of the
shelf as measured at permanent pool (feet)
Depth max over shelf =
0.50
Perimeter perm. pool =
530
Width submerged part of shelf =
3
Vshelf =
397.5
Vpp =
28,367
A bot. shelf =
8,667
Davg =
3.23
Minimum Average Depth Required =
3 ft
Average Depth Provided =
3.23 ft
Project No.: 22000-0600
Date: September 2022

Drawdown Calculations
CCBCC Fayetteville 21 September 2022

Wet Pond Drawdown Calculations
for
+/-20,000-SF Distribution Facility Expansion for CCBCC-Fayetteville
Basin: Modified Existing Wet Pond
Basin Elevations
Orifice Inv. =
90.63 ft
Normal Pool =
90.63 ft
Temporary Pool Elevation =
93.63 ft
Storage Depth =
3 ft
Temporary Pool Volume =
47,195 cu ft
Orifice Outlet Flow Calculation
Q = CD A (2 g Hc,)°-5
Where: Q =
Discharqe (cfs)
Cp =
Coefficient of discharge per TaLile 6 (unidess)
A =
Cross -sectional area of orifice entrance (sq ft)
g =
Acceleration of gravity (32.2 WseO)
Ha =
Driving head from water surface to centroid
orifice (ft) *usually use JY./3 to compute
drawdown through an arrfice to reflect the fact
€hat head rs decreasing as drawdcwn occurs*
2-Day Drawdown Time:
Q = Temp. Pool Vol. (cf) / 2 day (s): Q =
0.2731
cfs
Cd =
0.6
g =
32.20
f/s
Ho/3 =
1
ft
Solve for A:
A =
0.0567
ftZ
A =
8.17
in
2-Day Orifice Diameter Required =
3.22
in
5-Day Drawdown Time:
Q = Temp. Pool Vol. (cf) / 5 day (s): Q =
0.1092
cfs
Solve for A:
A =
0.0227
ftZ
A =
3.27
in
5-Day Orifice Diameter Required =
2.04
in
Orfice Diameter Provided =
3.00
in
A =
7.07
in
Q =
0.2364
cfs
Drawdown Time Provided =
2.31
days
Project No.: 22000-0600
Date: September 2022

Rip -Rap Sizing Calculations
CCBCC Fayetteville 23 September 2022

User Input Data
Calculated Value
Reference Data
Designed By: EDH Date: 9/13/2022
Checked By: EDH Date: 9/13/2022
Company: Fitts and Goodwin, Inc.
Project Name: Distribution Facility Expansion for CCBCC-Fayetteville
Project No.: 22000-0600
Site Location (City/Town) Fayetteville
Culvert Id. Basin Outlet Pipe
Total Drainage Area (acres) 8.07
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe. If the tailwater depth is less
than halfthe outlet pipe diameter, it is classified mgngmum railwater condition.
If it is greater than half the pipe diameter, it is classified maximum condition.
Pipes that outlet onto wide flat areas with no defined channel are assumed
to have a riu m,an tailwater condition unless reliable flood stage elecatioas
show otherwise.
Outlet pipe diameter, Do (in.) 36
Tailwater depth (in.) 24
Minimum/Maximum tailwater? Max TW (Fig. 8.06b)
Discharge (cfs) 65
Velocity (ft./s) 9.12
Step 2. Based on the tailtvater conditions determined nt step 1. enter Figure
8 06a or Figure 8 06b, and determine d50 nprap size and minimum apron length
(L.,. The d, size is the median stone size in a well -graded ripiap apron_
Step 3. Determine apron width at the pipe outlet, the apron shape_ and the
apron width at the outlet end from the same figure used in Step 2.
Minimum TW Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.)
Minimum apron length, La (ft.)
Apron width at pipe outlet (ft.) 9 9
Apron shape Trapezoid
Apron width at outlet end (ft.) 3 13
Step 4. Determine the maximum stone diameter:
d_ = 1.5 x dso
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.) 0 0.75
Step 5. Determine the apron thickness:
Apron thickness = 1.5 x d_
Minimum TW Maximum TW
Apron Thickness(ft.) 0 1.125
Step 6. Fit the riprap apron to the site by making it level for the minimum
length, L., from Figure 8.06a or Figure 8.06b. ]attend the apron farther
downstream and along channel banks until stability is assured. Keep the
apron as straight as possible and align it with the flow of the receiving stream.
Make any necessary alignment bends near the pipe outlet so that the entrance
into the receiving stream is straight.
Some locations may require hnmg of the entire channel cross section to assure
stability
It mtav be necessary to increase the size of Rprap where protection of the
channel side slopes is necessary (Appendix 8.0.5)_ Where overfalls exist at
pipe outlets or flows are excessive, a plunge pool should be considered see
page 8.06.8.
0.5
25