SW6241001_Stormwater Report_20241029

Stormwater Narrative and Calculations
NCDENR Stormwater Permit Submittal
For the proposed
FTCC/Cumberland County RF&RTC - PHASE 2
FULL SERVICES
Fayetteville, North Carolina
Prepared for
HH Architecture
Prepared By
Stewart
STEWART
Submitted on September 30, 2024

Stormwater Narrative
For
FTCC/Cumberland County RF&RTC - Phase 2 Full Services
Fayetteville, North Carolina
Prepared for:
HH Architecture
Prepared by:
Stewart
F-1536
223 S. West St. Suite 1100
Raleigh, NC 27603
919.380.8750
\.\ ,cN CARD %,
:
053759 : Z
09 30.2024 Q \
'FNGINE��''
/'1, ' PATHMP \\\
FOR REVIEW ONLY
Stewart Project No. L22067
September 30, 2024

Table of Contents
1. Table of Contents & Narrative
2. Site Information & Calculations
A. QUAD Map
B. FEMA Map
C. Web Soil Report
D. Rainfall Data
E. Drainage Area Maps
F. Drainage Calculations

STORMWATER DESIGN NARRATIVE
FTCC/CUMBERLAND COUNTY RF&RTC — PHASE 2 FULL SERVICES
FAYETTEVILLE, NORTH CAROLINA
Executive Summary
These calculations have been prepared specifically to address the
requirements of The North Carolina Department of Environmental and Natural
Resources SCM Manual.
Site Information
The proposed FTCC/Cumberland County Emergency Services Campus is located at
the Cumberland Industrial Center Lots 37 and 43 off Tom Starling Drive and
Corporation Drive in Fayetteville, NC (34.955139°N -78.891752°W). This parcel is
already developed. The current development phase increases additional impervious
to existing development.
The project is split into two area; the west parcel houses the administration /
classroom building whereas the east parcel houses the training village. Each parcel
has a wet detention pond that will capture post-construction runoff. Erosion control
devices utilized to control sediment transport will include stone construction
entrances, perimeter silt fence with outlets, inlet protection and concrete washout
areas.
Proposed Improvements
The proposed improvement in west parcel will include a parking area and
access road extensions. Vegetated swales will be used to treat the additional
runoffs. The east parcel improvements will be for extension of parking and building.
The existing wet detention pond (east) will be expanded to treat the portion of the
new built upon area (BUA) and additional vegetated swales will be utilized to
capture and treat remaining runoffs. See Appendix E for Drainage area exhibits.

SITE INFORMATION & CALCULATIONS
A. QUAD Map
B. FEMA Map
C. Web Soil Report
D. Rainfall Data
E. Drainage Area Maps
F. Drainage Calculations

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National Flood Hazard Layer FIRMette FEMA _Legend
78°53'49"W 34°57'33"N SEE EIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
Without Base Flood Elevation(BFE)
'W f1tiJ 1n`�one'AE. ' w 4 Zone A,V,A99
FLL�.r'7WAY�� With BFE or Depth Zone AE,AO,AH,VE,AR
�� i, SPECIAL FLOOD p
�!� �, \✓ ZOn@ iY�� HAZARD AREAS Regulatory Floodway
ri 4
"l% \ — ',j, 0.2%Annual Chance Flood Hazard,Areas
�/� of 1%annual chance flood with average
` depth less than one foot or with drainage
__Air / .... areas of less than one square mile zonex
Future Conditions 1%Annual
• Zone AE Chance Flood Hazard zonex
�" Area with Reduced Flood Risk due to
78 FEE OTHER AREAS OF
Levee.See Notes.Zone X
. 4,,
r. T` FLOOD HAZARD Area with Flood Risk due to Leveezone D
V. • t
•
. iiiiiiht_'
NO SCREEN Area of Minimal Flood Hazard zonex
4, Effective LOMRs
t56.�<C� Zone AE OTHER AREAS Area of Undetermined Flood Hazard Zone D
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GENERAL ----- Channel,Culvert,or Storm Sewer
4� STRUCTURES 1 1 1 1 1 1 1 Levee,Dike,or Floodwall
1 0 20.2 Cross Sections with 1%Annual Chance IP
-E-( tZ•s Water Surface Elevation
CUMBER. • D cou le, a Coastal Transect
•••••513^^^^"• Base Flood Elevation Line(BFE)
370076 Limit of Study
r �A Jurisdiction Boundary
--- Coastal Transect Baseline
AREA OEMINIMAL FLOOD HAZARD OTHER _ - Profile Baseline
37200433001 / FEATURES Hydrographic Feature
eft. 1/5/2007
.4 Digital Data Available N
•
No Digital Data Available
MAP PANELS Unmapped
J\. `e 9 The pin displayed on the map is an approximate
point selected by the user and does not represent
V:+ilLspir. 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.
; •r The basemap shown complies with FEMA's basemap
‘ , :le
i accuracy standards
r•
+ • The flood hazard information is derived directly from the
authoritative NFHL web services provided by FEMA.This map
i • was exported on 1/18/2021 at 3:24 PM and does not
4 • , ` reflect changes or amendments subsequent to this date and
time.The NFHL and effective information may change or
• become superseded by new data over time.
e t • 4 This map image is void if the one or more of the following map
diAlltilk
s ti A _ elements do not appear:basemap imagery,flood zone labels,
legend,scale bar,map creation date,community identifiers,
78°53'12'W 34°57'3"N FIRM panel number,and FIRM effective date.Map images for
Feet 1.6 00o unmapped and unmodernized areas cannot be used for
0 250 500 1,000 1,500 2,000 regulatory purposes.
Basemap:USGS National Map:Orthoimagery:Data refreshed October,2020

Soil Map—Cumberland County,North Carolina
Li
(FTCC) M
IA
692270 692350 692430 692510 692590 692670 692750 692830 692910 692990
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692270 692350 692430 692510 692590 692670 692750 692830 692910 692990
3 3
.12
Map Scale:1:3,530 if printed on A landscape(11"x 8.5")sheet.
Meters N
0 50 100 200 300
Feet
0 150 300 600 900
Map projection:Web Mercator Comer coordinates:WGS84 Edge tics:UTM Zone 17N WGS84
USDA Natural Resources Web Soil Survey 1/18/2021
Conservation Service National Cooperative Soil Survey Page 1 of 3

Soil Map—Cumberland County,North Carolina
(FTCC)
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 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.
(9 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: Cumberland County,North Carolina
Q Miscellaneous Water Survey Area Data: Version 21,Jun 2,2020
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: Jul 1,2018—Jul 31,
2018
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 1/18/2021
Conservation Service National Cooperative Soil Survey Page 2 of 3

Soil Map—Cumberland County, North Carolina FTCC
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
GdB Gilead loamy sand,2 to 8 3.1 12.0%
percent slopes
KaA Kalmia loamy sand,0 to 2 14.1 54.7%
percent slopes
KeA Kenansville loamy sand,0 to 3 2.3 8.9%
percent slopes
TR Torhunta and Lynn Haven soils 6.3 24.4%
Totals for Area of Interest 25.9 100.0%
USDA Natural Resources Web Soil Survey 1/18/2021
Conservation Service National Cooperative Soil Survey Page 3 of 3

NOAA Atlas 14,Volume 2,Version 3
° """ , Location name: Fayetteville, North Carolina, USA* ''''''°`°
i If A Latitude: 34.9545°, Longitude: -78.8928° norm
Elevation:m/ft**
source:ESRI Maps "a y.
**source:USGS ,"`""`'
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M.Bonnin,D.Martin,B.Lin,T.Parzybok,M.Yekta,and D.Riley
NOAA,National Weather Service,Silver Spring,Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/hour)1
Average recurrence interval(years)
Duration
1 2 5 10 25 50 100 - 200 500 1000
5-min 5.21 6.16 7.19 7.98 8.95 9.67 10.4 I 11.0 11.9 12.6
(4.74-5.76) (5.59-6.80) (6.53-7.96) (7.22-8.81) (8.08-9.85) (8.70-10.6) (9.28-11.4) (9.83-12.1) (10.5-13.0) (11.0-13.8)
10-min 4.16 4.92 5.76 6.38 7.13 7.70 8.24 8.75 9.41 9.89
(3.78-4.60) (4.47-5.44) (5.23-6.37) (5.78-7.04) i (6.43-7.85) (6.92-8.45) (7.37-9.03) I (7.79-9.58) (8.30-10.3) (8.67-10.8)
15-min 3.46 4.12 4.86 5.38 6.03 6.50 6.94 7.36 7.89 8.28
(3.15-3.83) (3.74-4.56) (4.41-5.37) (4.87-5.94) (5.44-6.64) (5.84-7.13) (6.21-7.61) (6.55-8.06) (6.96-8.64) (7.25-9.06)
30-min 2.38 2.85 3.45 3.90 4.47 4.89 5.32 5.73 6.28 I 6.70
(2.16-2.63) (2.59-3.15) (3.13-3.81) (3.53-4.30) (4.03-4.91) _(4.40-5.37) (4.75-5.83) (5.10-6.27) (5.54-6.87) (5.87-7.34)
60-min 1.48 1.79 2.21 2.54 2.97 3.32 3.66 4.02 4.51 4.89
(1.35-1.64) (1.62-1.98) (2.01-2.44) (2.30-2.80) (2.68-3.27) I (2.98-3.64) (3.27-4.01) (3.58-4.40) (3.97-4.93) I (4.29-5.36)
2-hr 0.864 1.05 1.33 1.54 1.84 2.08 2.32 2.57 2.92 3.20
(0.772-0.988) (0.937-1.20) (1.18-1.51) (1.37-1.76) (1.63-2.09) (1.83-2.36) (2.03-2.64) (2.24-2.92) (2.52-3.31) (2.74-3.63)
3-hr 0.611 0.741 0.941 1.10 1.33 1.52 1.72 1.93 2.22 2.47
(0.547-0.702) (0.662-0.850) (0.838-1.08) (0.981-1.26) (1.18-1.52) (1.33-1.73) (1.50-1.95) (1.67-2.19) (1.90-2.53) (2.09-2.81)
6-hr 0.366 0.444 0.564 0.663 0.802 0.917 1.04 1.17 1.36 1.52
(0.328-0.414) (0.398-0.501) (0.505-0.636) (0.591-0.746) (0.710-0.900) (0.807-1.03) (0.908-1.17) (1.01-1.31) (1.16-1.52) (1.28-1.69)
12-hr 0.214 0.260 0.332 0.392 0.477 0.549 0.626 0.710 0.833 0.934
(0.192-0.242) (0.233-0.293) (0.297-0.375) (0.348-0.441) (0.421-0.535) (0.481-0.614) (0.544-0.699) (0.610-0.791) (0.705-0.926) (0.781-1.04)
24-hr 0.126 0.153 0.196 0.231 0.281 0.321 0.364 0.410 0.475 0.528
(0.117-0.137) (0.142-0.167) (0.182-0.213) (0.213-0.251) (0.257-0.305) (0.293-0.348) (0.331-0.396) (0.371-0.445) (0.426-0.517) (0.470-0.576)
2-day 0.073 0.089 0.113 0.132 0.159 0.181 0.205 0.230 0.265 0.294
(0.068-0.079) (0.082-0.096) (0.104-0.122) (0.122-0.142) (0.146-0.172)1(0.166-0.196) (0.187-0.222)1(0.208-0.249) (0.238-0.288) (0.262-0.320)
3-day 0.052 0.063 0.079 0.092 0.111 0.126 0.142 0.159 0.182 0.201
(0.048-0.056) (0.058-0.068) (0.073-0.085) (0.086-0.099) (0.102-0.119) (0.116-0.136) (0.130-0.153) (0.144-0.171) (0.164-0.198) (0.180-0.219)I
4-day 0.041 0.050 0.062 0.073 0.087 0.098 0.110 0.123 0.141 0.155
(0.038-0.044) (0.046-0.053) (0.058-0.067) (0.067-0.078) (0.080-0.093) (0.090-0.106) (0.101-0.119) (0.112-0.133) (0.127-0.152) (0.139-0.168)
7-day 0.027 0.033 0.041 0.047 0.056 0.063 0.070 0.078 0.088 0.097
(0.025-0.029) (0.031-0.035) (0.038-0.044) (0.044-0.051) (0.052-0.060) (0.058-0.068) (0.064-0.076) (0.071-0.084) (0.080-0.096) (0.087-0.105)
10-day 0.022 0.026 0.032 0.037 0.043 0.048 0.053 0.058 0.065 0.071
(0.021-0.023) (0.025-0.028) (0.030-0.034) (0.034-0.039) (0.040-0.046) (0.044-0.051) (0.049-0.056) (0.053-0.062) (0.059-0.070) (0.064-0.076)
20-day 0.015 0.018 0.021 0.024 0.028 0.031 0.034 0.037 0.041 0.044
(0.014-0.016) (0.017-0.019) (0.020-0.022) (0.022-0.025) (0.026-0.029) (0.028-0.033) (0.031-0.036) (0.034-0.039) (0.038-0.044)1(0.040-0.048)
30-day 0.012 0.015 0.017 0.019 0.022 0.024 0.026 0.028 0.031 0.033
(0.012-0.013) (0.014-0.015) (0.016-0.018) (0.018-0.020) (0.020-0.023) (0.022-0.025) (0.024-0.028) (0.026-0.030) (0.029-0.033) (0.030-0.035)
45-day 0.010 0.012 0.014 0.016 0.018 0.019 0.021 0.022 0.024 0.026
(0.010-0.011) (0.012-0.013) (0.013-0.015) (0.015-0.017) (0.017-0.019) (0.018-0.020) (0.019-0.022) (0.021-0.024) (0.022-0.026) (0.024-0.027)
60-day 0.009 0.011 0.013 0.014 0.015 0.017 0.018 0.019 0.021 0.022
(0.009-0.010) (0.010-0.012) (0.012-0.013) (0.013-0.015) (0.015-0.016) (0.016-0.018) (0.017-0.019) (0.018-0.020) (0.019-0.022) (0.020-0.023)1
1 Precipitation frequency(PF)estimates in this table are based on frequency analysis of partial duration series(PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90%confidence interval.The probability that precipitation frequency estimates(for
a given duration and average recurrence interval)will be greater than the upper bound(or less than the lower bound)is 5%.Estimates at upper bounds are not
checked against probable maximum precipitation(PMP)estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
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PF graphical

PDS-based intensity-duration-frequency (IDF) curves
Latitude: 34.9545°, Longitude: -78.8928°
100.000 — 1-1-1 , I , ,
Average recurrence
interval
-- 10.000 --- - _ (years)
C
Q
N 5
c — 25
o
0.100 - ` — 50
a � `_ — 100
200
a` 0-010 --
''' 500
— 1000
0.001 -I
c C C c c E- ) 2 )E >, >,>. >. >, >, >, >,>.
'F - •- '- 'E L L L L L 40 40 /0 N 40 2
2 40 40
O -I rn 0D r-1 N N Ar- N O o LA O
I rfl cr ID
Duration
100.000 I 1 1
10.000 -••
L
C
Duration
71 1.000 — 5-nun — 2-day
— 10-nun — 3-day
15-min — 4-day
2 0-100 — 30-min — 7-day
._ 60-nrn 10 day
— 2-hr — 20-day
a` 0.010 - — 3-hr — 30-day
— 6-hr — 45-day
— 12-hr — 60-day
0.001 — 24-hr
1 2 5 10 25 50 100 200 500 1000
Average recurrence interval (years)
NOAA Atlas 14,Volume 2,Version 3 Created(GMT):Tue May 2 18:59:08 2023
Back to Top
Maps & aerials
Small scale terrain

+4 r LE
y�l1i
4n '5 Fi r'
j-lope Mills
_.—
"111611111111
3km
2mi
Lar a scale terrain
lin stop-sal ern }
• • Durham
Greensboro Rocky Mount
Raleigh
•
' RTH CAROLINA
•Greenville
•Char otte Fayettevill-1
Jacksonville
CAROLINA Wilmington Onn
• 111
•
>luml. 100km
I i
60mi
{{ � Large scale// map
Winston- lem Greensboro• Ddrham
Rocky Mount
Raleigh
• Greenville
North
Carolina
• arlotte
•
1ayetteville
I IJacksonville
+ ,
Wilmington
•umbia _
100km
`ou
a?gilt 60mi
Large scale aerial

Winston-Salem
Greensboro Durham. Rocky Mount
Raleigh •
• Greenville
North - •
Carolina
Charlotte
• Fayetteville
• Jacksonville
Wilmington MI
Cdumbia
100km
Sot
Car. 60mi -
Back to Top
US Department of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
National Water Center
1325 East West Highway
Silver Spring,MD 20910
Questions?:[e-mail]
Disclaimer

NOAA Atlas 14,Volume 2,Version 3
° "" , Location name: Fayetteville, North Carolina, USA* , '°°
Latitude: 34.9545°, Longitude: -78.8928° none
Elevation:m/ft**
i
*source:ESRI Maps "a y.
**source:USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M.Bonnin,D.Martin,B.Lin,T.Parzybok,M.Yekta,and D.Riley
NOAA,National Weather Service,Silver Spring,Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1
Average recurrence interval(years)
Duration 1 2 5 10 25 50 100 200 500 1000
5-min 0.434 0.513 0.599 0.665 0.746 0.806 0.864 0.920 0.991 1.05
(0.395-0.480) (0.466-0.567) (0.544-0.663) (0.602-0.734) (0.673-0.821) (0.725-0.884) (0.773-0.947) (0.819-1.01) (0.874-1.09) (0.917-1.15)
10-min 0.693 0.820 0.960 ' 1.06 1.19 1.28 1.37 1.46 1.57 1.65
(0.630-0.767) (0.745-0.907) (0.872-1.06) (0.963-1.17) (1.07-1.31) (1.15-1.41) (1.23-1.51) (1.30-1.60) (1.38-1.72) (1.45-1.81)
15-min 0.866 1.03 I 1.21 1.35 1.51 1.63 1.74 1.84 1.97 2.07
(0.788-0.958) (0.936-1.14) (1.10-1.34) (1.22-1.49) (1.36-1.66) (1.46-1.78) (1.55-1.90) (1.64-2.01) (1.74-2.16) (1.81-2.27)
30-min 1.19 1.42 1.73 1.95 2.23 2.45 2.66 2.86 3.14 3.35
(1.08-1.31) (1.29-1.57) (1.57-1.91) (1.77-2.15) (2.01-2.46) (2.20-2.69) (2.38-2.91) (2.55-3.14) (2.77-3.44) (2.94-3.67)
60-min 1.48 1.79 2.21 2.54 2.97 3.32 3.66 4.02 4.51 4.89
(1.35-1.64) (1.62-1.98) 1 (2.01-2.44) (2.30-2.80) (2.68-3.27) (2.98-3.64) (3.27-4.01) (3.58-4.40) (3.97-4.93) (4.29-5.36)
2-hr 1.73 2.10 2.65 3.09 3.67 4.15 I 4.64 5.15 I 5.84 6.40
(1.54-1.98) (1.87-2.39) (2.37-3.02) (2.74-3.51) (3.25-4.18) (3.66-4.72) (4.06-5.27) (4.48-5.84) (5.04-6.63) (5.48-7.27)
3-hr 1.84 2.23 I 2.83 3.31 4.00 4.56 5.15 5.78 6.68 7.41
(1.64-2.11) (1.99-2.55) (2.52-3.23) (2.95-3.79) (3.53-4.56) (4.00-5.20) (4.49-5.87) (5.00-6.58) (5.71-7.60) (6.27-8.43)
6-hr 2.19 2.66 3.38 3.97 4.80 5.49 6.23 7.01 8.14 9.07
(1.97-2.48) (2.38-3.00) (3.02-3.81) (3.54-4.47) (4.25-5.39) (4.83-6.16) (5.44-6.98) (6.07-7.84) (6.96-9.10) (7.67-10.1)
12-hr I 2.58 3.13 4.00 4.72 5.75 6.62 7.55 8.56 10.0 11.3
(2.32-2.92) (2.80-3.53) I (3.57-4.51) (4.20-5.31) (5.07-6.45) (5.80-7.40) (6.55-8.42) (7.35-9.53) (8.49-11.2) (9.41-12.5)
24-hr 3.03 3.68 I 4.71 5.55 6.74 7.71 8.74 9.84 11.4 12.7
(2.81-3.30) (3.41-4.00) (4.36-5.12) (5.12-6.03) (6.18-7.31) (7.04-8.36) , (7.94-9.49) (8.89-10.7) (10.2-12.4) (11.3-13.8)
2-day 3.52 4.26 5.40 6.33 7.64 8.71 9.85 11.0 12.7 14.1
(3.27-3.81) (3.96-4.60) (5.01-5.84) (5.85-6.84) (7.02-8.25) (7.97-9.41) (8.96-10.6) (9.99-12.0) (11.4-13.8) (12.6-15.4)
3-day 3.74 4.51 5.69 6.65 7.99 9.07 10.2 11.4 13.1 14.5
(3.48-4.03) (4.21-4.87) (5.29-6.14) (6.16-7.16) (7.36-8.60) (8.33-9.77) (9.33-11.0) (10.4-12.3)I (11.8-14.2) (13.0-15.8)
4-day 3.96 4.78 5.99 6.96 8.33 9.44 10.6 11.8 13.5 14.9
(3.70-4.26) (4.46-5.13) (5.57-6.43) , (6.47-7.48) (7.70-8.94) (8.69-10.1) (9.71-11.4) (10.8-12.7) (12.2-14.6) (13.4-16.1)
7-day 4.60 5.52 6.85 1 7.91 9.37 10.6 11.8 13.1 14.8 16.2
(4.28-4.95) (5.14-5.94) (6.37-7.38) (7.34-8.51) (8.66-10.1) (9.72-11.4) (10.8-12.7) (11.9-14.1) (13.4-16.1) (14.6-17.6)
10-day 5.26 6.30 7.68 8.77 10.3 11.4 12.6 13.9 15.6 16.9
(4.93-5.63) (5.90-6.73) I (7.18-8.22) (8.19-9.37) (9.54-11.0) (10.6-12.2) (11.7-13.5) (12.8-14.9) (14.2-16.8) (15.4-18.3)
20-day 7.09 8.42 I 10.1 11.4 13.3 14.7 16.1 17.6 19.6 21.2
(6.67-7.56) (7.92-8.99) (9.50-10.8) (10.7-12.2) r(12.4-14.1) (13.7-15.7) (15.0-17.2) (16.3-18.8) (18.1-21.1) (19.4-22.8)
30-day 8.84 10.5 12.3 13.8 15.7 17.2 18.7 20.2 22.2 23.8
(8.34-9.39) (9.87-11.1) (11.6-13.1) (13.0-14.7) (14.7-16.7) (16.1-18.3) (17.5-19.9) (18.8-21.6) (20.6-23.8) (21.9-25.5)
45-day 11.2 13.2 15.3 16.9 19.1 20.7 22.3 23.9 26.0 27.6
(10.6-11.8) (12.4-13.9) (14.5-16.2) (16.0-17.9) (18.0-20.2) (19.5-22.0) (20.9-23.7) (22.3-25.4) (24.2-27.7) (25.6-29.5)
60-day 13.4 15.7 18.1 19.9 22.3 24.0 25.7 27.4 29.6 31.3
1 (12.7-14.1) (14.9-16.6) I (17.2-19.1) I (18.9-21.0) (21.0-23.5) (22.7-25.3) I (24.2-27.2) I (25.7-29.0) (27.7-31.4) (29.2-33.2)�
1 Precipitation frequency(PF)estimates in this table are based on frequency analysis of partial duration series(PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90%confidence interval.The probability that precipitation frequency estimates
(for a given duration and average recurrence interval)will be greater than the upper bound(or less than the lower bound)is 5%.Estimates at upper bounds
are not checked against probable maximum precipitation(PMP)estimates and may be higher than currently valid PMP values.
Please refer to NOAAAtlas 14 document for more information.
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PF graphical

PDS-based depth-duration-frequency (DDF) curves
Latitude: 34.9545°, Longitude: -78.8928°
35 I 1 1 1
Average recurrence
30 internal
(years)
25 • — 1
O. 2
w 20 — 5
co — 10
•0 15 - — 25
•a — 50
v — 100
E 10 -
tL — 200
500
5 = -- --- •' — 1000
0 — . . .
c c c c c - - - 6- I- >, >,>, >. >, >, >, >,• >,
'F .- •- '- •- L L ',cry
L .0 40 40 /0 N 40 2
10 40 40
ul O in M 6 r-1 N N N A 4 r- O o o
0 rnD
Duration
35 1
30 -
-` 25 - Duration
-c
a
v 20 - =' P
— 2 day— 3-day— 4-day— 7-day— 10-day•
• - — 20-day— 30-day— 45-day
• • - — 12-hr — 60-day
0 — 1 1 t 1 I -1 ` — 24-hr
1 2 5 10 25 50 100 200 500 1000
Average recurrence interval (years)
NOAA Atlas 14,Volume 2,Version 3 Created(GMT):Tue May 2 18:37:52 2023
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Maps & aerials
Small scale terrain

+4 r LE
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_.—
"111611111111
3km
2mi
Lar a scale terrain
lin stop-sal ern }
• • Durham
Greensboro Rocky Mount
Raleigh
•
' RTH CAROLINA
•Greenville
•Char otte Fayettevill-1
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CAROLINA Wilmington Onn
• 111
•
>luml. 100km
I i
60mi
{{ � Large scale// map
Winston- lem Greensboro• Ddrham
Rocky Mount
Raleigh
• Greenville
North
Carolina
• arlotte
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1ayetteville
I IJacksonville
+ ,
Wilmington
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100km
`ou
a?gilt 60mi
Large scale aerial

Winston-Salem
Greensboro Durham. Rocky Mount
Raleigh •
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North - •
Carolina
Charlotte
• Fayetteville
• Jacksonville
Wilmington MI
Cdumbia
100km
Sot
Car. 60mi -
Back to Top
US Department of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
National Water Center
1325 East West Highway
Silver Spring,MD 20910
Questions?:[e-mail]
Disclaimer

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f =_== ' ' VARIABLE PUBLIC R W s t u
0 --' II
II
FTCC, CUMBERLAND COUNTY REGIONAL SEPTEMBER 30,2024
FIRE AND RESCUE TRAINING FACILITY, 4‘,1: 3)
PHASE 2
0 30 60 120 NORTH
SCALE:1"=60' S T E WA RT

A
STEWART
Project: FTCC Ph II Date 7.11.2024 Revision: 0
Project No: C22067 By: MLP
Wet Detention Pond Sizing Calculations (90% TSS Removal)
calculation Method - Simple Method
EAST WET POND
Input values in red
Drainage Area
Total Drainage Area (sf) 176,684
Impervious Area (sf) 107,498
Other Areas (sf) 69,186
Required Surface Area I Required Storage Volume
Total Drainage Area = 4.06 ac Storage Volume Required
Total Impervious Area = 2.47 ac
Percent Impervious = 60.84% Total Drainage Area = 4.06 ac
Design Rainfall Depth = 1 in Total Impervious Area = 2.4678145 ac
Percent Impervious = 61%
Average Perm. Pool Depth = 4.53 ft
Max. Perm. Pool Depth = 6.5 ft Rv = 0.05 + 0.009(I)
SA/DA Ratio = 1.67 I = % impervious = 61%
Rv = 0.60 in
Surface Area Required = 2947 sf
0.07 ac Runoff Vol. Req'= 8799 cf
Surface Area Required at Normal Pool = 2,947 sf
Surface Area Provided at Normal Pool = 5,558 sf
Temporary Storage Volume Required = 8,799 cf
Temporary Storage Volume Provided = 9,653 cf
STRONGER BY DESIGN 421 FAYETTEVILLE ST. SUITE 400 RALEIGH,NC 27603 T 919.380.8750 F 919.380.8752

r��
STEWART
Project: FTCC Ph II Date: 7.11.2024 Revision 0
Project No: C22067 By: MLP
EAST WET POND
Input values in red
Storage Volume Required Basin Characteristics
Discrete NRCS Method - 7,085 Pond Invert = 79.00 ft
Normal Pool Elevation = 85.50 ft
Simple Method - 8,799 Next available Outlet = 86.85 ft
Storage Depth = 1.35 ft
Req' Runoff Volume = 7,085 cf Driving Head (H/3)= 0.45 ft
Ks = 6819
Provided Runoff Volume = 9,653 cf b= 1.16
Minimum depth
Provided Surface Area = 8,282 sf required for storage = 1.03 ft
Find orifice size for 2-day drawdown time
Flow Rate = Volume (cf) / Time (sec)
= 0.0410 cfs
Q=CD*A*(2*g*h)^(1/2) (Orifice Equation - solve for A (area))
A= 0.01269 ft2
1.82794 in2
Orifice Size (2 day) = 1.53 in (dia)
Find orifice size for 5-day drawdown time
Flow Rate = Volume (cf) / Time (sec)
= 0.0164 cfs
Q=CD*A*(2*g*h)^(1/2) (Orifice Equation - solve for A (area))
A= 0.00508 ft2
0.73118 in2
Orifice Size (5 day) = 0.96 in (dia)
Select orifice size between 2 and 5 day size
Size selected = 1.5 " dia
Actual Drawdown Times
Required Volume = 7,085 cf
Provided Volume = 9,653 cf
Pipe Size = 1.5 "dia
Area = 0.0122718 ft2
Flow Rate = 0.0396379 cfs
Req' Drawdown Time = 2.07 days
Prov' Drawdown Time = 2.82 days
STRONGER BY DESIGN 421 FAYETTEVILLE ST. SUITE 400 RALEIGH,NC 27603 T 919.380.8750 F 919.380.8752

romil
ST E WA R T TIME OF CONCENTRATION (PER NRCS TR-55 METHOD)
POST-DEV_DA2 CAPTURE 9/30/2024
SHEET FLOW
SEGMENT ID 1
1 SURFACE DESCRIPTION(table 3-1) GRASS
2 MANNING'S ROUGHNESS COEFFICIENT, n (table 3-1) 0.410
3 FLOW LENGTH, L-ft (less than 300 ft) 0
4 TWO-YEAR 24-hr RAINFALL DEPTH, P2-in (per local rainfall data) 3.50
5 LAND SLOPE,s-ft/ft 0.330
6 CALCULATION STEP 0.000 hrs
0.0070/L)°8
Tt P o.s s0.4
2
SHALLOW CONCENTRATED FLOW
SEGMENT ID 2.1 2.2
7 SURFACE DESCRIPTION(PAVED OR UNPAVED) PAVED
8 FLOW LENGTH, L-ft 217
9 WATERCOURSE SLOPE,s-ft/ft 0.01
10 AVERAGE VELOCITY,V(fig 3-1) 4.6
11 CALCULATION STEP 0.013 0 hrs
SHALLOW CONCENTRATED TOTAL Tc-HOURS 0.013
L
Tr =
3600 V
CHANNEL FLOW
SEGMENT ID 3.1 3.2 3.3 3.4 3.5
12 CROSS SECTIONAL FLOW AREA,a-ft2 5
13 WETTED PERIMETER,pW-ft 8.32
14 HYDRAULIC RADIUS, r=a/pw -ft 0.601 0 0 0 0
15 CHANNEL SLOPE,s-ft/ft 0.01
16 MANNING'S ROUGHNESS COEFFICIENT, n 0.41
17 CALCULATE VELOCITY,ft/s2 0.26
1.49 r213s112
V =
n
18 FLOW LENGTH, L-ft 163
19 CALCULATE Tt 0.175
L
Tt = 3600 V
20 CHANNEL FLOW TOTAL Tc-HOURS 0.175
WATERSHED AREA TOTAL Tc-HOURS 0.188
MINIMUM TIME OF CONCENTRATION FOR
11.3 m i n
HYDROGRAPHS IS 5 MIN.

romil
ST E WA R T TIME OF CONCENTRATION (PER NRCS TR-55 METHOD)
POST-DEV_DA3 CAPTURE 7/12/2024
SHEET FLOW
SEGMENT ID 1
1 SURFACE DESCRIPTION(table 3-1) GRASS
2 MANNING'S ROUGHNESS COEFFICIENT, n (table 3-1) 0.410
3 FLOW LENGTH, L-ft (less than 300 ft) 0
4 TWO-YEAR 24-hr RAINFALL DEPTH, P2-in (per local rainfall data) 3.50
5 LAND SLOPE,s-ft/ft 0.330
6 CALCULATION STEP 0.000 hrs
0.007(nnL)°8
Tt P o.s 50.4
2
SHALLOW CONCENTRATED FLOW
SEGMENT ID 2.1 2.2
7 SURFACE DESCRIPTION(PAVED OR UNPAVED) PAVED
8 FLOW LENGTH, L-ft 60
9 WATERCOURSE SLOPE,s-ft/ft 0.05
10 AVERAGE VELOCITY,V(fig 3-1) 4.6
11 CALCULATION STEP 0.004 0 hrs
SHALLOW CONCENTRATED TOTAL Tc-HOURS 0.004
L
Tr =
3600 V
CHANNEL FLOW
SEGMENT ID 3.1 3.2 3.3 3.4 3.5
12 CROSS SECTIONAL FLOW AREA,a-ft2 5
13 WETTED PERIMETER,pW-ft 8.32
14 HYDRAULIC RADIUS, r=a/pw -ft 0.601 0 0 0 0
15 CHANNEL SLOPE,s-ft/ft 0.01
16 MANNING'S ROUGHNESS COEFFICIENT, n 0.41
17 CALCULATE VELOCITY,ft/s2 0.26
1.49 r213s112
V =
n
18 FLOW LENGTH, L-ft 352
19 CALCULATE Tt 0.378 0 0 0 0
L
Tt = 3600 V
20 CHANNEL FLOW TOTAL Tc-HOURS 0.378
WATERSHED AREA TOTAL Tc-HOURS 0.381
MINIMUM TIME OF CONCENTRATION FOR
22.9 m i n
HYDROGRAPHS IS 5 MIN.

ST E WA R T TIME OF CONCENTRATION (PER NRCS TR-55 METHOD)
POST-DEV_DA4 CAPTURE 7/12/2024
SHEET FLOW
SEGMENT ID 1
1 SURFACE DESCRIPTION(table 3-1) ASPHALT
2 MANNING'S ROUGHNESS COEFFICIENT, n (table 3-1) 0.011
3 FLOW LENGTH, L-ft (less than 300 ft) 0
4 TWO-YEAR 24-hr RAINFALL DEPTH, P2-in (per local rainfall data) 3.50
5 LAND SLOPE,s-ft/ft 0.330
6 CALCULATION STEP 0.000 hrs
0.007(nnL)°8
Tt P o.s 50.4
2
SHALLOW CONCENTRATED FLOW
SEGMENT ID 2.1 2.2
7 SURFACE DESCRIPTION(PAVED OR UNPAVED) PAVED
8 FLOW LENGTH, L-ft 120
9 WATERCOURSE SLOPE,s-ft/ft 0.02
10 AVERAGE VELOCITY,V(fig 3-1) 4.6
11 CALCULATION STEP 0.007 0 hrs
SHALLOW CONCENTRATED TOTAL Tc-HOURS 0.007
L
Tr =
3600 V
CHANNEL FLOW
SEGMENT ID 3.1 3.2 3.3 3.4 3.5
12 CROSS SECTIONAL FLOW AREA,a-ft2 5
13 WETTED PERIMETER,pW-ft 8.32
14 HYDRAULIC RADIUS, r=a/pw -ft 0.601 0 0 0 0
15 CHANNEL SLOPE,s-ft/ft 0.01
16 MANNING'S ROUGHNESS COEFFICIENT, n 0.41
17 CALCULATE VELOCITY,ft/s2 0.26
1.49 r213s112
V =
n
18 FLOW LENGTH, L-ft 90
19 CALCULATE Tt 0.097 0 0 0 0
L
Tt = 3600 V
20 CHANNEL FLOW TOTAL Tc-HOURS 0.097
WATERSHED AREA TOTAL Tc-HOURS 0.104
MINIMUM TIME OF CONCENTRATION FOR
6.2 min
HYDROGRAPHS IS 5 MIN.

ST E WA R T TIME OF CONCENTRATION (PER NRCS TR-55 METHOD)
POST-DEV_DA5 CAPTURE 7/12/2024
SHEET FLOW
SEGMENT ID 1
1 SURFACE DESCRIPTION(table 3-1) ASPHALT
2 MANNING'S ROUGHNESS COEFFICIENT, n (table 3-1) 0.011
3 FLOW LENGTH, L-ft (less than 300 ft) 0
4 TWO-YEAR 24-hr RAINFALL DEPTH, P2-in (per local rainfall data) 3.50
5 LAND SLOPE,s-ft/ft 0.330
6 CALCULATION STEP 0.000 hrs
0.007(nnL)°8
Tt P o.s 50.4
2
SHALLOW CONCENTRATED FLOW
SEGMENT ID 2.1 2.2
7 SURFACE DESCRIPTION(PAVED OR UNPAVED) PAVED
8 FLOW LENGTH, L-ft 210
9 WATERCOURSE SLOPE,s-ft/ft 0.02
10 AVERAGE VELOCITY,V(fig 3-1) 4.6
11 CALCULATION STEP 0.013 0 hrs
SHALLOW CONCENTRATED TOTAL Tc-HOURS 0.013
L
Tr =
3600 V
CHANNEL FLOW
SEGMENT ID 3.1 3.2 3.3 3.4 3.5
12 CROSS SECTIONAL FLOW AREA,a-ft2 5
13 WETTED PERIMETER,pW-ft 8.32
14 HYDRAULIC RADIUS, r=a/pw -ft 0.601 0 0 0 0
15 CHANNEL SLOPE,s-ft/ft 0.01
16 MANNING'S ROUGHNESS COEFFICIENT, n 0.41
17 CALCULATE VELOCITY,ft/s2 0.26
1.49 r213s112
V =
n
18 FLOW LENGTH, L-ft 543
19 CALCULATE Tt 0.583 0 0 0 0
L
Tt = 3600 V
20 CHANNEL FLOW TOTAL Tc-HOURS 0.583
WATERSHED AREA TOTAL Tc-HOURS 0.595
MINIMUM TIME OF CONCENTRATION FOR
35.7 m i n
HYDROGRAPHS IS 5 MIN.

I
STE WA R T
Vegetated Swale Sizing
North Carolina Erosion and Sedimentation Planning and Design Manual
(Calculations based on 10-yr storm and 3600 cf/ ac of disturbed area)
Project Name: FTCC FTCC Phase 2 Vegetated Swale ID: DA2
Project #: C22067 Trap Location:
Flow: Disturbed earth = 1.39 @ c= 0.50
Undist., wooded areas = 0.00 @ c= 0.25
Undist., grassy areas = 0.00 @ c= 0.30
Other areas = 0.00 @ c= 0.95
Total Area (ac) @ c= 0.50
Time of Concentration "Tc" = 11.30 min
10-year Intensity = 6.12 in/hr (from local i-d-f curve/table)
Flow "Q10 = CIA" = 4.26 cfs
V10 3.06 fps GOOD

I
STE WA R T
Vegetated Swale Sizing
North Carolina Erosion and Sedimentation Planning and Design Manual
(Calculations based on 10-yr storm and 3600 cf/ ac of disturbed area)
Project Name: FTCC FTCC Phase 2 Vegetated Swale ID: DA3
Project #: C22067 Trap Location:
Flow: Disturbed earth = 0.54 @ c= 0.50
Undist., wooded areas = 0.00 @ c= 0.25
Undist., grassy areas = 0.00 @ c= 0.30
Other areas = 0.00 @ c= 0.95
Total Area (ac) = 0.54 @ c= 0.50
Time of Concentration "Tc" = 22.90 min
10-year Intensity = 4.60 in/hr (from local i-d-f curve/table)
Flow "Q10 = CIA" = 1.24 cfs
V10 2.30 fps GOOD

I
STE WA R T
Vegetated Swale Sizing
North Carolina Erosion and Sedimentation Planning and Design Manual
(Calculations based on 10-yr storm and 3600 cf/ ac of disturbed area)
Project Name: FTCC FTCC Phase 2 Vegetated Swale ID: DA4
Project #: C22067 Trap Location:
Flow: Disturbed earth = 0.25 @ c= 0.50
Undist., wooded areas = 0.00 @ c= 0.25
Undist., grassy areas = 0.00 @ c= 0.30
Other areas = 0.00 @ c= 0.95
Total Area (ac) = 0.25 @ c= 0.50
Time of Concentration "Tc" = 6.20 min
10-year Intensity = 7.60 in/hr (from local i-d-f curve/table)
Flow "Q10 = CIA" = 0.95 cfs
V10 3.80 fps GOOD

I
STE WA R T
Vegetated Swale Sizing
North Carolina Erosion and Sedimentation Planning and Design Manual
(Calculations based on 10-yr storm and 3600 cf/ ac of disturbed area)
Project Name: FTCC FTCC Phase 2 Vegetated Swale ID: DA5
Project #: C22067 Trap Location:
Flow: Disturbed earth = 1.41 @ c= 0.50
Undist., wooded areas = 0.00 @ c= 0.25
Undist., grassy areas = 0.00 @ c= 0.30
Other areas = 0.00 @ c= 0.95
Total Area (ac) = 1.41. @ c= 0.50
Time of Concentration "Tc" = 36.00 min
10-year Intensity = 3.63 in/hr (from local i-d-f curve/table)
Flow "Q10 = CIA" = 2.56 cfs
V10 1.81 fps GOOD