SW6210505_Stormwater Report_20210723

Stormwater Narrative and Calculations
NCDENR Stormwater Permit Submittal
For the proposed
FTCC/Cumberland County - Emergency
Services Campus
Fayetteville, North Carolina
Prepared for
HH Architecture
Prepared By
Stewa rt
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1
AU
STEWART
1ST Submittal: 01.18.2021
2nd Submittal: 05.12.2021
3rd Submittal: 07.22.2021

Stormwater Narrative
For
FTCC/Cumberland County - Emergency Services Campus
Fayetteville, North Carolina
Prepared for:
HH Architecture
Prepared by:
Stewart
223 S. West St. Suite 1100
Raleigh, NC 27603
919.380.8750
L,IIP10rrr0,,l
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1all11174ti3tik
FOR REVIEW ONLY
Stewart Project No. L19032
July 22, 2021

STORMWATER DESIGN NARRATIVE
FTCC/CUMBERLAND COUNTY — EMERGENCY SERVICES CAMPUS
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). The parcel is
currently undeveloped. The parcels combined acreage is 30.0 acres with 6.85 acres
of disturbance with the current development phase.
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. The wet detention ponds will be used as sediment basins during
construction. Additional 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 west parcel will include a classroom building, surface parking area and
training facilities. The east site will predominately be used for training. Both sites
will capture a portion of the new built upon area (BUA) and treat with wet detention
ponds. Both sites fall below the BUA threshold for Low Density however a portion
of the BUA is captured with piped convenances. The areas captured with piped
convenances are directed to the wet detention ponds.
Drainage Areal (West Parcel) has a total area of 16.40ac with 2.35 ac of
total BUA (14.35%). Drainage Area 2 (East Parcel) has a total area of 14.00 ac
with 1.86 ac of BUA (13.28%).
The West wet detention pond captures runoff from 2.90 ac of drainage area
including 1.55 ac of BUA. The East wet detention pond captures runoff from 2.14
ac of drainage area including 1.71 ac of BUA.

Site Information

The National Map
USTopo
HOPE MILLS QUADRANGLE
NORTH CAROLINA
7.5-MINUTE SERIES
88 89 90 91 92 93
-78.8750°
75
74
73
72
71
70
35.000(

National Flood Hazard Layer FI RMette
78o53'49"W 34o57'33"N
10 FEMA
I -.t7,000
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 With BFE or Depth ZoneAE,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
Chance Flood Hazard Zonex
Area with Reduced Flood Risk due to
OTHER AREAS OF Levee. See Notes. zone
FLOOD HAZARD O'j 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
,— Base Flood Elevation Line (BFE)
Limit of Study
Jurisdiction Boundary
— --- Coastal Transect Baseline
OTHER _ Profile Baseline
FEATURES Hydrographic Feature
Digital Data Available AN
No Digital Data Available
MAP PANELS Unmapped
PA
The 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 1/18/2021 at 3:24 PM 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.

692270
340 57 26" N g
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1
34o 579" N
692270 692350 692430 692510 692590 692670
b
M 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 Conermordinates: WGS84 Edge tics: UTM Zone 17N WGS84
USDA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
Soil Map —Cumberland County, North Carolina
(FTCC)
692350 692430 692510 692590 692670 692750
692830 692910
692750 692830 692910
0
6992990
34o 5726" N
mo
r
�i
r
�i
r
�i
1 34o 579" N
692990
b
1 /18/2021
Pagel of 3

MAP LEGEND
Area of Interest (AOI)
Area of Interest (AOI)
Soils
0
Soil Map Unit Polygons
0
Soil Map Unit Lines
Soil Map Unit Points
Special
Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
,
Gravelly Spot
Landfill
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
oa
Sodic Spot
Soil Map —Cumberland County, North Carolina
(FTCC)
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
. - Special Line Features
Water Features
Streams and Canals
Transportation
Rails
,., Interstate Highways
US Routes
Major Roads
Local Roads
Background
N 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: Cumberland County, North Carolina
Survey Area Data: Version 21, Jun 2, 2020
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jul 1, 2018—Jul 31,
2018
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.
USDA 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
percent slopes
3.1
12.0%
KaA
Kalmia loamy sand, 0 to 2
percent slopes
14.1
54.7%
KeA
Kenansville loamy sand, 0 to 3
percent slopes
2.3
8.9%
TR
Torhunta and Lynn Haven soils
6.3
24.4%
Totals for Area of Interest
26.9
100.0%
USDA Natural Resources Web Soil Survey 1/18/2021
Conservation Service National Cooperative Soil Survey Page 3 of 3

Wet Pond Sizing Calculations

A
STEWART
Project: FTCC 06.17.2020 Revision: 0
Project No: L19032 DMB
Drainage Area Characteristics / Curve Number Method
West Wet Pond
Input values in red
Total Drainage Area = 126,274 sf
Directly Connected Impervious Area = 67,446 sf
CN for re
Soil Type
A B C D
Developed Urban Areas
sf
sf
sf
sf
Open Space turf areas - Poor; <50% grass cover
0
0
0
0
Open Space turf areas - Fair; 50% - 75% grass cover
0
0
0
0
Open Space turf areas - Good; >75% grass cover
0
58,828
0
0
Impervious Areas
0
0
0
0
Gravel Areas
0
0
0
0
Bare compacted dirt
0
0
0
0
Developing Urban Areas
sf
sf
sf
sf
Bare uncom acted areas
0
0
0
0
Pasture - Poor; <50% ground cover
0
0
0
0
Pasture - Fair; 50% - 75% ground cover
0
0
0
0
Pasture - Good; >75% ground cover
0
0
0
0
Meadow - continuous grass, not grazed or mowed
0
0
0
0
Brush - Poor; <50% ground cover
0
0
0
0
Brush - Fair; 50% - 75% ground cover
0
0
0
0
Brush - Poor; <50% ground cover
0
0
0
0
Woods - Poor
0
0
0
0
Woods - Fair
0
0
0
0
Woods - Good
1 0
1 0
1 0
0
STRONGER BY DESIGN 233 S. WEST ST. SUITE 1100 RALEIGH, NC 27603 T 919.380.8750 F 919.380.8752

A
STEWART
Project: FTCC Date 06.17.2020 0
Project No: L19032 By: DMB
Wet Detention Pond Sizing Calculations (90% TSS Removal)
:alculation Method - Discrete NRCS Curve Number Method
West Wet Pond
Input values in red
Draina a Area from revious tab
Total Drainage Area (sf)
126,274
Directly Connected Imp (sf)
67,446
Disconnected Imp (sf)
0
Other Areas (sf)
58,828
Directly Connected Imp CN
98
Remainder CN
61
Required Surface Area
Required Storage Volume
Total Drainage Area =
2.90 ac
Discrete NRCS CN Method
Total Impervious Area =
1.55 ac
Percent Impervious =
53.41%
S = (1000/CN) - 10
Design Rainfall Depth =
1 in
Q* = (P-0.2S)2/ (P+0.8S)
S
Q* Volume (cf)
Average Perm. Pool Depth =
3.71 ft
Directly Connected Imp 0.204
0.791 4,445.29
Max. Perm. Pool Depth =
5.5 ft
Remainder of Drainage Area 0.000
0.00000 0.00
SA/DA Ratio =
1.68
Temporary Storage Vol Required =
4,445 cf
Surface Area Required =
2126 sf
=
0.05 ac
Surface Area Required at Normal Pool = 2,126 sf
Surface Area Provided at Normal Pool = 2,401 sf
Temporary Storage Volume Required = 4,445 cf
Temporary Storage Volume Provided = 4,750 cf
STRONGER BY DESIGN 421 FAYETTEVILLE ST. SUITE 400 RALEIGH, NC 27603T 919.380.8750 F 919.380.8752

A
STEWART
Project: FTCC Date 06.17.2020 0
Project No: L19032 By: DMB
Wet Detention Pond Sizing Calculations (90% TSS Removal)
alculation Method - Simple Method
West Wet Pond
Input values in red
Drainage Area
Total Drainage Area (sf) 126,274
Impervious Area (sf) 67,446
Other Areas (sf) 58,828
Required Surface Area
Required Storage Volume
Total Drainage Area =
2.90 ac
Storage Volume Required
Total Impervious Area =
1.55 ac
Percent Impervious =
53.41%
Total Drainage Area =
2.90 ac
Design Rainfall Depth =
1 in
Total Impervious Area = 1.5483471 ac
Percent Impervious =
53%
Average Perm. Pool Depth =
3.71 ft
Max. Perm. Pool Depth =
5.5 ft
Rv = 0.05 + 0.009(I)
SA/DA Ratio =
1.60
I = % impervious =
53%
Rv =
0.53 in
Surface Area Required =
2024 sf
=
0.05 ac
Runoff Vol. Re '= 5585 cf
Surface Area Required at Normal Pool = 2,024 sf
Surface Area Provided at Normal Pool = 2,401 sf
Temporary Storage Volume Required = 5,585 cf
Temporary Storage Volume Provided = 4,750 cf
STRONGER BY DESIGN 421 FAYETTEVILLE ST. SUITE 400 RALEIGH, NC 27603T 919.380.8750 F 919.380.8752

STEWART
Project:
Project No:
West Wet Pond
Input values in red
FTCC _,. 06.17.2020
L19032 By: DMB
Stage -Storage Analysis
Revision:
Contour
(ft)
Area
(ft2)
Incr
Vol
(ft3)
Accum
Vol
(ft3)
Stage
Z
(ft)
In S
In Z
Zest
90.5
2401
0
0
0
91
2989
1348
1348
0.5
7.206
-0.693
0.503
92
3634
3312
4659
1.5
8.447
0.405
1.475
93
4336
7325
8673
2.5
9.068
0.916
2.529
b = 1.15
Ks = 2977
STRONGER BY DESIGN 421 FAYETTEVILLE ST. SUITE 400 RALEIGH, NC 27603 T 919.380.8750 F 919.380.8752

"D
STEWART
Project: FTCC
Project No: L19032
West Wet Pond
Input values in red
Forebay Bottom Elev =
Forebay Berm Elev =
Main Pond Bottom Elev =
Bottom Of Veg. Shelf Elev =
Normal Pool Elev =
Top Of Veg. Shelf Elev =
Top of Dam Elev =
Forebav Volume
Date: 06.17.2020 Revision
By: DMB
Volume Calculations -
85 ft
84.5 ft
85 ft
90 ft
90.5 ft
91 ft
94 ft
Contour
(ft)
Area
(ft2)
Incr
Vol
(ft3)
Accum
Vol
(ft3)
85
96
0
0
86
138
117
117
87
185
162
279
88
237
211
490
89
294
265
755
90
355
324
1079
90.5
456
203
1282
Pond Volume
Contour
(ft)
Area
(ft2)
Incr
Vol
(ft3)
Accum
Vol
(ft3)
85
385
0
0
86
1 552
468
468
87
740
646
1114
88
948
844
1958
89
1174
1061
3019
90
1420
1297
4316
90.5
1824
811
5127
Forebay Vol (NP) = 1282 cf
Total Vol (NP)= 6409 cf
Volume above Normal Pool
I
Contour
(ft)
Area
(ft2)
Incr
Vol
(ft3)
Accum
Vol
(ft3)
90.5
2401
0
0
91
2989
1348
1348
92
3634
3312
4659
93
4336
3985
8644
Average Depth of Permanent pool to use
in the SA DA tables ft
Vperm_pool =
6409 cf
Aperm_pool =
2401 sf
Abot shelf =
sf
Abot_pond =
552 sf
Depth =
5 ft
Option 1: day =
2.67 ft
Option 2: day =
3.71 ft
Forebay equals 20.0% of total volume
421 FAYETTEVILLE ST. SUITE 400 RALEIGH, NC 27603 T 919.380.8750 F 919.380.8752

STEWART
Project: FTCC Date 06.17.2020
Project No: L19032 By: DMB
Water Quality Drawdown Calculations
West Wet Pond
Input values in red
5:
Storage Volume Required
Basin Characteristics
Discrete NRCS Method -
4,445
Pond Invert =
85.00 ft
Normal Pool Elevation =
90.50 ft
Simple Method -
5,585
Next available Outlet =
ft
Storage Depth =
1.50 ft
Req' Runoff Volume =
4,445 cf
Driving Head (H/3)=
0.50 ft
Ks =
2977
Provided Runoff Volume =
4,750 cf
b=
1.15
Minimum depth
Provided Surface Area =
3,650 sf
required for storage =
1.42 ft
Find orifice size for 2-day drawdown time
Flow Rate = Volume (cf) / Time (sec)
0.0257 cfs
Q=CD*A*(2*g*h)^(1/2) (Orifice Equation - solve for A (area))
A= 0.00756 ftZ
1.08803 in
Orifice Size 2 day) = 1.18 in dia
Find orifice size for 5-day drawdown time
Flow Rate = Volume (cf) / Time (sec)
0.0103 cfs
Q=CD*A*(2*g*h)^(1/2) (Orifice Equation - solve for A (area))
A= 0.00302 ftZ
0.43521 in
Orifice Size 5 day) = 0.74 in dia
act orifice size between 2 and 5 day size
Size selected � i " dia -W
aal Drawdown Times
Required Volume = 4,445 cf
Provided Volume = 4,750 cf
Pipe Size = 1 "dia
Area = 0.0054542 ftZ
Flow Rate = 0.0185698 cfs
Reg' Drawdown Time = 2.77 day
Prov' Drawdown Time = 2.96 day
STRONGER BY DESIGN 421 FAYETTEVILLE ST. SUITE 400 RALEIGH, NC 27603T 919.380.8750 F 919.380.8752

A
STEWART
Project: FTCC 06.17.2020 Revision: 0
Project No: L19032 DMB
Drainage Area Characteristics / Curve Number Method
EAST WET POND
Input values in red
Total Drainage Area = 93,304 sf
Directly Connected Impervious Area = 74,636 sf
CN for re
Soil Type
A B C D
Developed Urban Areas
sf
sf
sf
sf
Open Space turf areas - Poor; <50% grass cover
0
0
0
0
Open Space turf areas - Fair; 50% - 75% grass cover
0
0
0
0
Open Space turf areas - Good; >75% grass cover
0
18,668
0
0
Impervious Areas
0
0
0
0
Gravel Areas
0
0
0
0
Bare compacted dirt
0
0
0
0
Developing Urban Areas
sf
sf
sf
sf
Bare uncom acted areas
0
0
0
0
Pasture - Poor; <50% ground cover
0
0
0
0
Pasture - Fair; 50% - 75% ground cover
0
0
0
0
Pasture - Good; >75% ground cover
0
0
0
0
Meadow - continuous grass, not grazed or mowed
0
0
0
0
Brush - Poor; <50% ground cover
0
0
0
0
Brush - Fair; 50% - 75% ground cover
0
0
0
0
Brush - Poor; <50% ground cover
0
0
0
0
Woods - Poor
0
0
0
0
Woods - Fair
0
0
0
0
Woods - Good
1 0
1 0
1 0
0
STRONGER BY DESIGN 233 S. WEST ST. SUITE 1100 RALEIGH, NC 27603 T 919.380.8750 F 919.380.8752

A
STEWART
Project: FTCC Date 06.17.2020 0
Project No: L19032 By: DMB
Wet Detention Pond Sizing Calculations (90% TSS Removal)
:alculation Method - Discrete NRCS Curve Number Method
EAST WET POND
Input values in red
Drainage Area from revious tab
Total Drainage Area (sf)
93,304
Directly Connected Imp (sf)
74,636
Disconnected Imp (sf)
0
Other Areas (sf)
18,668
Directly Connected Imp CN
98
Remainder CN
61
Required Surface Area
Required Storage Volume
Total Drainage Area =
2.14 ac
Discrete NRCS CN Method
Total Impervious Area =
1.71 ac
Percent Impervious =
79.99%
S = (1000/CN) - 10
Design Rainfall Depth =
in
Q* = (P-0.2S)2/ (P+0.8S)
S
Q* Volume (cf)
Average Perm. Pool Depth =
4.26 ft
Directly Connected Imp 0.204
0.791 4,919.17
Max. Perm. Pool Depth =
6.5 ft
Remainder of Drainage Area 0.000
0.00000 0.00
SA/DA Ratio =
2.94
Temporary Storage Vol Required =
4,919 cf
Surface Area Required =
2740 sf
=
0.06 ac
Surface Area Required at Normal Pool = 21740 sf
Surface Area Provided at Normal Pool = 2,887 sf
Temporary Storage Volume Required = 4,919 cf
Temporary Storage Volume Provided = 5,027 cf
STRONGER BY DESIGN 421 FAYETTEVILLE ST. SUITE 400 RALEIGH, NC 27603T 919.380.8750 F 919.380.8752

A
STEWART
Project: FTCC Date 06.17.2020 0
Project No: L19032 By: DMB
Wet Detention Pond Sizing Calculations (90% TSS Removal)
alculation Method - Simple Method
EAST WET POND
Input values in red
Drainage Area
Total Drainage Area (sf) 93,304
Impervious Area (sf) 74,636
Other Areas (sf) 18,668
Required Surface Area
Required Storage Volume
Total Drainage Area =
2.14 ac
Storage Volume Required
Total Impervious Area =
1.71 ac
Percent Impervious =
79.99%
Total Drainage Area =
2.14 ac
Design Rainfall Depth =
in
Total Impervious Area = 1.7134068 ac
Percent Impervious =
80%
Average Perm. Pool Depth =
4.26 ft
Max. Perm. Pool Depth =
6.5 ft
Rv = 0.05 + 0.009(I)
SA/DA Ratio =
1.98
I = % impervious =
80%
Rv =
0.77 in
Surface Area Required =
1851 sf
=
0.04 ac
Runoff Vol. Re '= 5986 cf
Surface Area Required at Normal Pool = 11851 sf
Surface Area Provided at Normal Pool = 2,887 sf
Temporary Storage Volume Required = 5,986 cf
Temporary Storage Volume Provided = 5,027 cf
STRONGER BY DESIGN 421 FAYETTEVILLE ST. SUITE 400 RALEIGH, NC 27603T 919.380.8750 F 919.380.8752

0
STEWART
Project: FTCC 06.17.2020 Revision:
Project No: L19032 DMB
Stage -Storage Analysis -
EAST WET POND
Input values in red
Contour
(ft)
Area
(ft2)
Incr
Vol
(ft3)
Accum
Vol
(ft3)
Stage
Z
(ft)
In S
In Z
Zest
85.5
2887
0
0
0
86
3523
1603
1603
0.5
7.379
-0.693
0.512
87
4215
3869
5472
1.5
8.607
0.405
1.450
88
4964
8487
10090
2.5
9.219
0.916
2.437
89
5770
9985
15457
3.5
9.646
1.253
3.499
90
6631
11595
21685
4.5
9.984
1.504
4.663
b = 1.18
Ks = 3529
STRONGER BY DESIGN 421 FAYETTEVILLE ST. SUITE 400 RALEIGH, NC 27603 T 919.380.8750 F 919.380.8752

"D
STEWART
Project: FTCC
Project No: L19032
EAST WET POND
Input values in red
Forebay Bottom Elev =
Forebay Berm Elev =
Main Pond Bottom Elev =
Bottom Of Veg. Shelf Elev =
Normal Pool Elev =
Top Of Veg. Shelf Elev =
Top of Dam Elev =
Forebav Volume
Date: 06.17.2020 Revision
By: DMB
Volume Calculations -
79 ft
85 ft
79 ft
85 ft
85.5 ft
86 ft
90 ft
Contour
(ft)
Area
(ft2)
Incr
Vol
(ft3)
Accum
Vol
(ft3)
79
106
0
0
80
149
128
128
81
198
173
301
82
251
224
525
83
309
280
805
84
371
340
1145
85
439
405
1549
85.5
549
247
1796
Pond Volume
Contour
(ft)
Area
(ft2)
Incr
Vol
(ft3)
Accum
Vol
(ft3)
79
424
0
0
80
1 597
511
511
81
790
694
1205
82
1002
896
2101
83
1234
1118
3219
84
1484
1359
4579
85
1754
1619
6198
85.5
2194
987
7185
Forebay Vol (NP) = 1796 cf
Total Vol (NP)= 8981 cf
Volume above Normal Pool
I
Contour
(ft)
Area
(ft2)
Incr
Vol
(ft3)
Accum
Vol
(ft3)
85.5
2887
0
0
86
3523
1603
1603
87
4215
3869
5472
88
4964
4590
10061
89
5770
5367
15428
90
6631
6201
21629
Average Depth of Permanent pool to use
in the SA DA tables ft
Vperm_pool =
8981 cf
Aperm_pool =
2887 sf
Abot shelf =
sf
Abot_pond =
597 sf
Depth =
6 ft
Option 1: day =
3.11 ft
Option 2: day =
4.26 ft
Forebay equals 20.0% of total volume
421 FAYETTEVILLE ST. SUITE 400 RALEIGH, NC 27603 T 919.380.8750 F 919.380.8752

STEWART
Project: FTCC Date 06.17.2020
Project No: L19032 By: DMB
Water Quality Drawdown Calculations
EAST WET POND
Input values in red
5:
Storage Volume Required
Basin Characteristics
Discrete NRCS Method -
4,919
Pond Invert =
79.00 ft
Normal Pool Elevation =
85.50 ft
Simple Method -
5,986
Next available Outlet =
86.85 ft
Storage Depth =
1.35 ft
Req' Runoff Volume =
4,919 cf
Driving Head (H/3)=
0.45 ft
Ks =
3529
Provided Runoff Volume =
5,027 cf
b=
1.18
Minimum depth
Provided Surface Area =
4,391 sf
required for storage =
1.33 ft
Find orifice size for 2-day drawdown time
Flow Rate = Volume (cf) / Time (sec)
0.0285 cfs
Q=CD*A*(2*g*h)^(1/2) (Orifice Equation - solve for A (area))
A= 0.00881 ftZ
1.26914 in
Orifice Size 2 day) = 1.27 in dia
Find orifice size for 5-day drawdown time
Flow Rate = Volume (cf) / Time (sec)
0.0114 cfs
Q=CD*A*(2*g*h)^(1/2) (Orifice Equation - solve for A (area))
A= 0.00353 ftZ
0.50766 in
Orifice Size 5 day) = 0.80 in dia
act orifice size between 2 and 5 day size
Size selected � i " dia -W
aal Drawdown Times
Required Volume = 4,919 cf
Provided Volume = 5,027 cf
Pipe Size = 1 "dia
Area = 0.0054542 ftZ
Flow Rate = 0.0176168 cfs
Reg' Drawdown Time = 3.23 day
Prov' Drawdown Time = 3.30 day
STRONGER BY DESIGN 421 FAYETTEVILLE ST. SUITE 400 RALEIGH, NC 27603T 919.380.8750 F 919.380.8752

r/ r:
STEWART
RIPRAP OUTLET PROTECTION WORKSHEET
Project FTCC EMERGENCY SERVICES CAMPUS
Project No.
L19032
Outlet ID
O1-FES
Outlet flowrate
6.48
cfs
Pipe diameter
15
inches
Outlet pipe slope
1
percent
Full flow velocity
5.28
ft/sec
Fieure 8.06.b.1
Date 2020.10.05
Designer CBC
25
Zone 7 '
20
Zone 6
U
15
w
J;
2 10
Zone 5
Zone 4-
5
Zone 1-1 sec Zone 3 '
Zone -2 -
0
0 1 2 3 4 5 6 7 8 9 10
Pipe diameter (ft)
Zone from graph above =
1
Outlet pipe diameter
15 in.
Length =
5.0 ft.
Outlet flowrate
6.5 cfs
Width =
3.8 ft.
Outlet velocity
5.3 ft/see
Stone diameter =
3 in.
Material =
Class A
Thickness =
9 in.
Zone
Material
Diameter
Thickness
Length
Width
1
Class A
3
9
4 x D(o)
3 x D(o)
2
Class B
6
22
6 x D(o)
3 x D(o)
3
Class I
13
22
8 x D(o)
3 x D(o)
4
Class I
13
22
8 x D(o)
3 x D(o)
5
Class 11
23
27
10 x D(o)
3 x D(o)
6
Class 11
23
27
10 x D(o)
3 x D(o)
7
Special study required
Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual
223 S. West Street, Suite 1100, Raleigh, NC 27603 Tel [phone] Fax [phone] www.stewart-eng.com

r/ r:
STEWART
RIPRAP OUTLET PROTECTION WORKSHEET
Project FTCC EMERGENCY SERVICES CAMPUS
Project No.
L19032
Outlet ID
40-FES
Outlet flowrate
10.53
cfs
Pipe diameter
18
inches
Outlet pipe slope
1
percent
Full flow velocity
5.96
ft/sec
Fieure 8.06.b.1
Date 2020.10.05
Designer CBC
25
Zone 7
20
Zone 6
U
15
w
41
Zone 5
10
Zone -4-
5 5 96 ft/sec Zane 3
Zone 1
Zone 2-
0
0 1 2 3 4 5 6 7 8 9 10
Pipe diameter (ft)
Zone from graph above =
1
Outlet pipe diameter
18 in.
Length =
6.0 ft.
Outlet flowrate
10.5 cfs
Width =
4.5 ft.
Outlet velocity
6.0 ft/see
Stone diameter =
3 in.
Material =
Class A
Thickness =
9 in.
Zone
Material
Diameter
Thickness
Length
Width
1
Class A
3
9
4 x D(o)
3 x D(o)
2
Class B
6
22
6 x D(o)
3 x D(o)
3
Class I
13
22
8 x D(o)
3 x D(o)
4
Class I
13
22
8 x D(o)
3 x D(o)
5
Class 11
23
27
10 x D(o)
3 x D(o)
6
Class 11
23
27
10 x D(o)
3 x D(o)
7
Special study required
Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual
223 S. West Street, Suite 1100, Raleigh, NC 27603 Tel [phone] Fax [phone] www.stewart-eng.com