SW6110103_Stormwater Report_20230127

CUI
JSOC - Microgrid
Project number: 60652522
Attachment D — Hydrology Report
AECOM
CUI

CUI
JSOC - Microgrid
Project number: 60652522
ATTACHMENT D — Table of Contents I REVISED
1. Stormwater Worksheets....................................................................................... 2
2. NCDEQ - BUA Figures and Worksheets............................................................... 6
3. EISA Section 438 Army LID Planning and Cost Tool Report ............................... 12
4. Hydraflow Hydrographs Output - Summary Reports .......................................... 14
5. Hydraflow Hydrographs Output - 10-Year Hydrograph and Routing Reports ..... 24
6. NOAAAtlas-14 Rainfall Data.............................................................................. 42
7. Bioretention Underdrain Calculations................................................................. 45
8. Erosion & Sediment Control - Outlet Protection Calculations ............................ 49
AECOM
161111

CUI
Stormwater Worksheets
CUI PN97470 - Page 2 of 58

CUI
JSOC Microgrid Installand and Integration
Project: 60652522 Date: 26 JAN 2023
Design By: ACF
Checked By:
Pre -Development
Drainage Areas
A=COM
READY -TO -ADVERTISE
REVISED
NRCS (HSG "A" SOILS)
RATIONAL
AREA A.0
Area, A (ac.)
CN
CN x A
55%
14%
0%
30.3% Imp.
CNw = 52
C
C x A
Cw = 0.32
Wooded
0.338
30
10.1
0.05
0.0169
Grassed
0.088
39
3.4
0.15
0.0132
#57 stone, 6 inches
0.000
46
0.0
0.20
0.0000
Impervious
0.186
98
18.2
0.90
0.1670
Subtotal
0.612
31.8
0.1971
AREA B.0
Area, A (ac.)
CN
CN x A
0%
13%
0%
86.9% Imp.
CNw = 90
C
C x A
Cw = 0.80
Wooded
0.000
30
0.0
0.05
0.0000
Grassed
0.040
39
1.6
0.15
0.0060
#57 stone, 6 inches
0.000
46
0.0
0.20
0.0000
Impervious
0.265
98
26.0
1
0.90
0.2389
Subtotal
0.305
27.6
0.2449
TOTAL PRE -DEVELOPED SITES 1 0.9171 1 59.34 1 CNw = 65 1 1 0.44 1 Cw = 0.48
MC_SWM_WORKSHEETS.xlsx, PreDev DAs- 1/26/202314:40 PM
1 of 3
CUI PN97470 - Page 3 of 58

CUI
JSOC Microgrid Installand and Integration
Project: 60652522 Date: 26 JAN 2023
Design By: ACF
Checked By:
Post -Development
Drainage Areas
A=COM
READY -TO -ADVERTISE
REVISED
NRCS (HSG "A" SOILS)
RATIONAL
AREA A.1 (to CONTAINMENT with
overflow to SCM)
Area, A (ac.)
CN
CN x A
0%
6%
1%
93.3% Imp.
CNw = 94
C
C x A
Cw = 0.85
Wooded
0.000
30
0.0
0.05
0.0000
Grassed
0.012
39
0.5
0.15
0.0018
#57 stone, 6 inches
0.002
46
0.1
0.20
0.0004
Impervious
0.195
98
19.1
0.90
0.1753
Subtotal
0.209
19.7
0.1775
AREA A.2 (to SCM - BIORETENTION)
Area, A (ac.)
CN
CN x A
0%
30%
0%
61.7% Imp.
8.7%
CNw = 81
C
C x A
Cw = 0.69
Wooded
0.000
30
0.0
0.05
0.0000
Grassed
0.099
39
3.9
0.15
0.0148
#57 stone, 6 inches
0.000
46
0.0
0.20
0.0000
Impervious
0.206
98
20.2
0.90
0.1855
Bioretention SCM
0.029
100
2.9
1.00
1 0.0290
Subtotal
0.334
27.0
0.2293
AREA A.3 (bypass SCM, uncontrolled)
Area, A (ac.)
CN
CN x A
0%
0%
0%
100.0% Imp.
CNw = 98
C
C x A
Cw = 0.90
Wooded
0.000
30
0.0
0.05
0.0000
Grassed
0.000
39
0.0
0.15
0.0000
#57 stone, 6 inches
0.000
46
0.0
0.20
0.0000
Impervious
0.069
98
6.8
0.90
0.0621
Subtotal
0.069
6.8
0.0621
AREA B.0 (bypass SCM, uncontrolled)
Area, A (ac.)
CN
CN x A
0%
0%
42%
57.6% Imp.
CNw = 76
C
C x A
Cw = 0.60
Wooded
0.000
30
0.0
0.05
0.0000
Grassed
0.000
39
0.0
0.15
0.0000
#57 stone, 6 inches
0.117
46
5.4
0.20
0.0235
Impervious
0.160
98
15.6
0.90
0.1437
Subtotal
0.2771
1 21.1
0.1672
AREA B.1 (to "Drainage Area 1 ") Area, A (ac.) I CN I CN x A C C x A
USE UNDERGROUND INFILTRATION TRENCH DISCHARGES FROM., -
ROUTING CALCULATIONS IN EXISTING PERMIT SW6110103 u.u000
2-yr = 0.19 cfs, 10-yr = 3.16 cfs, 25-yr = 5.47, 100-yr = 9.18 cfs - ,,,,r. _._J 0.0254
:Nw = 98 0.0254
Cw
TOTAL - AREA A.0
1 0.6121
1 53.37
1 CNw = 87
1
1 0.47
1 Cw = 0.77
TOTAL - AREA B.0
1 0.2771
1 21.05
1 CNw = 76
1
1 0.17
1 Cw = 0.60
TOTAL POST -DEVELOPED SITES
1 0.8891
1 74.42
1 CNw = 84
1
1 0.64
1 Cw = 0.72
JSOC_SWM_WORKS HEETS.xlsx, PostDev DAs- 1/26/202314:40 PM
2of3
CUI PN97470 - Page 4 of 58

cul
JSOC Microgrid Installand and Integration
Project: 60652522 Date: 26 JAN 2023
Design By: ACF
Checked By:
Peak Runoff Rate Comparison
A
B
C
D
E
F
G
H
J
K
L
M
A=COM
READY -TO -ADVERTISE
REVISED
SITE 1
Peak Runoff Rate (cfs)
95th
1- ear
2-year
10- ear
100- ear
Pre -Developed
0.00
0.02
0.18
1.02
2.91
Post -Developed
0.18
0.32
0.38
3.67
5.88
Runoff Difference (cfs) [B -A]
1 0.18
0.30
0.20
2.65
2.97
Runoff Difference (%) C / A
--
1500%
111%
260%
102%
SITE 2
Peak Runoff Rate (cfs)
95th
1- ear
2-year
10- ear
1 00-ear
Pre -Developed
0.53
1.14
1.45
2.29
3.61
Post -Developed
0.18
0.55
0.79
1.50
2.69
Runoff Difference (cfs) [F - E]
1 -0.35
-0.59
-0.66
-0.79
-0.92
Runoff Difference % G / E
-66%
-52%
-46%
-34%
-25%
SITES 1 & 2
Peak Runoff Rate (cfs)
95th
1- ear
2-year
10- ear
1 00-ear
Pre -Developed
0.53
1.14
1.59
3.29
6.48
Post -Developed
0.32
0.86
1.17
4.98
8.56
Runoff Difference (cfs) [K - J]
1 -0.21
-0.28
-0.42
1.69
2.08
Runoff Difference % L / J
-40%
-25%
-26%
51.4%
32%
Drainage Area and 10-Year Runoff Comparison
N
P
Q
R
Value
Overall Drainage Areas (acres)
45.5
Site Development Drainage Areas acres
0.92
Site vs. Overall % of Area N / P
2.02%
7
Site vs. Overall (% of 10-year Runoff) [M10YR X QJ
1.04%
(based on proportional area)
approximate % change in 10-year peak rate,
with respect to the overall drainage area
JSOC_SWM_WORKS HEETS.xlsx, Peak Rate Comparisons - 1/26/20231 4:40 PM
3of3
cul PN97470 - Page 5 of 58

CUI
NCDEQ — BUA Figures
and Worksheets
CUI PN97470 - Page 6 of 58

CUI
Q
Y
U
U
S��E�
2
E
OVERALL �� S�� EXISTING CULVERT
DRAINAGE AREA f 30" RCP @ 2.2%
ONL
A = 45.5 ac. EXISTING DITCH
m.
ALONG RAILROAD
L PROJECT AREA
'IJIL.57 ACRES JIM
LIM
OVERALL PROJECT AREA
1" = 1000'
L
Y
7
L LIM
Z
n
L
to,
N 0
O N
NO
N
O N
N O
" O
oU
av
No
mU)
J U) FZU
N U
oW
N
O 0
n
E
L
i•
/ _ A�.
I
A ddlk�
l \
`._
�❑ n
BUILDING
\
3-1549
i
FIGURE 2
"DRAINAGE AREA 1"
PROJECT AREA
= LIMIT OF WORK
= 155,722 SF (3.58 ACRES)
EXISTING UNDERGROUND
_ SWM INFILTRATION TRENCH
PERMIT #SW6110103
1 \ \
0 \
\
a
. � \ INV=24
J100\ y Pty.Pr
----
-
\
7L
INV = 241.6'
I
FIGI
EXISTING CULVEF
30" RCP @ 2.2%
Lu
W
Q
O
F-
a
W
to
cn
N
_-
- 100' 50' 0 100' 200'
DEVELOPMENT AREAS - SITE 1 & SITE 2 1"=100'
1000' 500' 0 1000, 2000'
1" = 100' 1"=1000'
co
0 W
z�
as
Lu
tU z
W
02
a 0
J J
J W
a>
�W
W o
O
co
co
0
o U
z z N
O O
t— N N
Z
H N
z � 0 2
LL Co
z O H
a z 0 N
z V a� N
O `��° N
Q00,0
c
JVOfl
ti � o
z �
L
Z
O W
40 O
�aU)Q
CUI PN97470 - Page 7 of 58

CUI
0
[FO7A.3(BYPASSES
ESIGN]
SCM)
0ac.)
EXISTING BUA = 2,536 SF lle�\
NEW BUA = 470 SF
[FOR 10-YEAR DESIGN]
AREA A.1
(TO CONTAINMENT)
9,097 SF (0.209 ac.)
8,486 SF IMPERVIOUS
[FOR TREATMENT DESIGN]
EXISTING BUA = 1,166 SF
NEW BUA = 7,320 SF
0
m
I----------`
1,191 SF NEW BUA
(BYPASSES SCM) -
k Uvils
TO DEVELOPMENT LEGEND
NEW SCM
FOR DETERMINATION OF "DEVELOPMENT' AND "BUILT -UPON A
12,890 SF DEVELOPMENT: NEW IMPERVIOUS
470 SF NEW IMPERVIOUS (NEW BUA - SUBJECT TO PERMITTING)
BYPASSING SCM EXISTING DEVELOPMENT: REMOVE IMPERVIOUS
[FOR 10-YEAR DESIGN] 1,023 SF (REMOVED BUA)
AREA A.2 (TO SCM) EXISTING DEVELOPMENT: ON EXISTING IMPERVI
14,550 SF (0.334 ac.) 4,576 SF F (EXISTING BUA)
8,980 SF IMPERVIOUS
1,262 SF BIORETENTION SCM
[FOR TREATMENT DESIGN]
EXISTING BUA = 3,410 SF
` NEW BUA = 5,570 SF
REMOVED BUA = 1,023 SF
[FOR 10-YEAR DESIGN]
TOTAL AREA A.0
(TO BMP FOR 10-YEAR)
` 23,647 SF (0.543 ac.)
17,466 SF IMPERVIOUS -
[FOR TREATMENT DESIGN]
° EXISTING BUA = 4,576 SF
° NEW BUA = 12,890 SF g\�E •��••'
REMOVED BUA = 1,023 SF •�••'�
''•_••••• S\FEZ
_••• "DRAINAGE AREA 1"
MATCHLINE - SEE FIGURE 3 FOR CONTINUATION
DEVELOPMENT AREA - SITE 1 50' 25' 0 50' 100,
ill = 50' 1 "=50' -Am— mmmmIIIIIl
N
0 i
aL
I.L
REVISED
w
H
Fna
aw
Lua
az
w�
a_j
05
w 00
w
0
Go
0
90
Z Z N
0 O
N N
Z
erl N m
6� N
Z 0 °?
LL
Z C H
az0N
Z v 101� CV
O � U) N
Q oo(0
J V Z �
Q LOL . .
r r 0
z Z N
L
Z
o�/ �W�
W ^ 0 O
� a U) Q
CUI PN97470 - Page 8 of 58

CUI
al
a
Y
U
BUILDING -
` 3-1549
\
SEE FIGURE 2 FOR AREA
` 60 SF EXISTING BUA (BYPASSES SC
\
MATCHLINE - SEE FIGURE 2 FOR CONTINUATION
UG SFARMIWPiCF
"DRAINAGE AREA 1"
E
` 361 SF EXISTING BUA = LIMI O K Q °
("DRA AGE AREA 1 ") � = 155 22 SF (1. 8
ID
O / A°V
o
° ° \ \ ��
83 SF N W BU�\( Y1 ES SCM)
v,_0
54
SF NEW BUA, ("DRAIN GE
\
AR
A l "); SEE FIGURE 2 F R
LO
ATION OF EXIS
`
5,623 S G BUA
v ''
PASSES SC
v,
\
\
5,117 SF REMOV BUA
(BYPASSES SCM)
INV = 241.6'
EXISTING CULVERT
30" RCP @ 2.2%
N
v \ V = 243.Q'
�v [FOR 10-YEAR PN] _
AREA B.0 (BYPA ES SC !
12,072 SF (0.277 ac )
6,957 SF IMPERVI S [1,229 o%RENCH]
EXISTING BUA = 5,6 3 SF [682 S t ENCH]
' NEW BUA = 1,274 SF [5 7 SF to T C
REMOVED BUA = 5,1 7 F
�\ o f �RENN ��NG
\
DEVELOPMENT AREA - SITE 2
ill =50'
IT�KZ y
TO EXISTING DEVELOPMENT LEGEND
BYPASSES TRENCH SCM
FOR DETERMINATION OF "DEVELOPMENT' AND "BUILT -UPON AREA" (BUA)
1,274 SF 547 SF DEVELOPMENT: NEW IMPERVIOUS
(NEW BUA -SUBJECT TO PERMITTING)
5,117 SF 0 SF EXISTING DEVELOPMENT: REMOVE IMPERVIOUS
(REMOVED BUA)
5,683 SF 682 SF EXISTING DEVELOPMENT: ON EXISTING IMPERVIOUS
(EXISTING BUA)
W
cn
Lu
0
0
W
N
ca
N
N
ZM
0 i
■■ 0)
n
REVISED
N
w
co co
aw
Lua
az
w�
a_j
05
w 00
w
0
Go
0
o 0
Z LL Z N
O N N
C�
Z
erl N m
H � N
?O °?
LL
Z O H
az0N
Z V 101� N
D 4� ~ N
Q O 0
J
V Z �
O ..
ti O
z
0 J_ O
L
�p �W�
16 ^ U O
� a U) Q
CUI PN97470 - Page 9 of 58

CUI
A=COM
10 South Jefferson Street, Suite 1600
Roanoke, Virginia 24011
Civil Calculation Sheet
JSOC - Microgrid
Fort Bragg, North Carolina
REVISED
Job No.: 60652522 Designed By: A. Freeland hecked By: Date: 26 JAN 2023
Subject: Treatment Volume (Required) -- Stormwater Control Measure Volume (Provided)
Job Title: JSOC Microgrid; Fort Bragg NC Rev. No.: 1
READY -TO -ADVERTISE
TREATMENT VOLUME
SITE #1 (Added to existing permit as "Drainage Area 2")
Values:
BUA (Impervious Area) = 12,890 sq. ft. = 0.30 acres
Treatment Depth = 1.00 inches (NCDEQ treatment storm)
Treatment Volume (minimum) = cu. ft. Required
Treatment Volume, Provided = I 1,0921cu. ft.
Notes:
(1) The provided treatment volume is taken at the 264.375 contour area of 1456
square feet for a depth of 0.75 feet (9 inches). The minimum filter media area at
contour elevation of 264.0 is 1,260 square feet.
(2) The containment tank provides 1,600 cubic feet of storage, which is held and
drained later to the bioretention SCM during dry periods.
(3) The required treatment volume is based only on development at Site 1. Any
reduction to development (impervious area) within Site 2 are excluded.
TREATMENT VOLUME
SITE #2 (new BUA contributing to "Drainage Area 1" of existing permit)
Values:
BUA (Impervious Area) = 547 sq. ft. = 0.01 acres
Treatment Depth = 1.00 inches (NCDEQ treatment storm)
Treatment Volume (minimum) = 46 cu. ft. Required
Treatment Volume, Provided =
Approximately
Notes:
2,0921cu. ft.
45.51times more volume than required
(1) The treatment volume is provided by the surplus treatment capacity of the
existing underground infiltration SCM. The original design required 4,750 cf of
treatment and provided 6,842 cf - resulting in a treatment volume surplus of 2,092
cf.. (Other documents state 6,991 cf is the provided volume)
JSOC-NCDEQ Treatment Worksheet.xlsx
Print Date: 1/26/2023
CUI PN97470 - Page 10 of 58

CUI
A=COM
10 South Jefferson Street, Suite 1600
Roanoke, Virginia 24011
Civil Calculation Sheet
JSOC - Microgrid
Fort Bragg, North Carolina
REVISED
AECOM Job No.: 60652522 Designed By: A. Freeland Checked By: B. Fisher
Subject: Bioretention - Infiltration Drawdown Check
Date: 26 JAN 2023
Page No.: 1
Job Title: JSOC - Microgrid Installation and Integration
Rev. No.: 1
INFILTRATION DRAWDOWN CALCULATION
r: immmum aurrace Nrea ror are irrrurrarrvrr >vsxem
SA = FS* DV * 12
K * T
where- SA = required minimum surface area of infiltration system (ft2)
FS = factor of safety (minimum of 2 is recommended)
OV = design volume (W)
K = hydraulic conductivity of soil (irVhr)
T = maximum dewatering time (72 hours)
Soil Infiltration (Ksat) Test Result
ID in/hr
ft/hr
B-2 46.77
3.90
Elevation @Test Location
SHWT = Seasonal High Water Table
Bioretention Infiltration
Maximum Ponded Depth
9.0 inches
Time to Drain - Average Test Rate
Maximum Allowed Drain Time
0.19 hrs
72 hrs
Time to Drain < 72 hours --> okay
Bottom Elevation
260.0 feet
Ground Elevation
268.2 feet
SHWT Depth
13.0 feet
SHWT Elevation
255.2 feet
Separation, Design (between Bottom and SHWT)
4.8 feet
Separation, Minimum Required
2.0 feet
Separation (design) > Separation (min) --> okay
Using NCDEQ Equation 2 (above) ...
FS =
2.0
DV =
1074
cu. Ft.
(minimum treatment volume, provided)
K =
0.5
in/hr
(use conservative minimum rate)
T =
72
hours
SA (min)
= 716
sq. ft.
(minimum surface area, calculated)
SA (design)
= 1260
sq. ft.
(minimum surface area, provided)
SA (design) > SA (min) --> okay
JSOC_NCDEQ Drawdown Worksheet.xlsx Print Date: 1/26/2023
CUI PN97470 - Page 11 of 58

CUI
EISA Section 438
Army LID Planning and Cost Tool Report
CUI PN97470 - Page 12 of 58

CUI
Army LID Planning and Cost Tool Report
PROJECT INFO SITE INFO AND EISA VOLUME
Date 8/30/2022 REQUIREMENT
Army Command IMCOM Project limit of disturbance (ac) 0.61
Army Installation Fort Bragg 95% rainfall depth (in) 1.8
Project name 60652522 - JSOC (SITE #1) Soil type Sandy
Project description
Site # 1 (0.61 acres)
User Name
Master Planner
Structural BMP
Bioretention:
Swale:
Permeable Pavement:
Rainwater Harvesting:
Green Roof:
Infiltration Practice:
Hydrologic Soil Group (HSG)
Pre -project curve number (CN)
Post -project curve number (CN)
IPC/ACF Pre -project runoff volume (cf)
Post -project runoff volume (cf)
EISA Section 438 retention volume
requirement (cf)
LID PLANNING SUMMARY
Surface area
(sf)
1260
9097
I
Runoff volume
retained (cf)
1506
0
0
1195
0
0
Total retention volume provided by BMPs (cf): 2701
Project complies with EISA Section 438.
A
52
87
0
1666
1666
Non-structural BMP Surface
area (ac)
Veg. Filter Strip (Slope >2%, Short Grass): 0.00
Veg. Filter Strip (Slope >2%, Tall Grass): 0.00
Veg. Filter Strip (Slope G2%, Short Grass): 0.00
Veg. Filter Strip (Slope G2%, Tall Grass): 0.00
Reforestation (Trees - Short Grass): 0.00
Reforestation (Trees - Shrubs and Tall Grass): 0.00
LID COST SUMMARY
CUI PN97470 - Page 13 of 58

CUI
Hydraflow Hydrographs Output
Summary Reports I REVISED
CUI PN97470 - Page 14 of 58

CUI
Hydraflow Table of Contents JSOC_SWM_Sites_RTA-Rev1.gpw
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4 Thursday, 01 / 26 / 2023
Watershed Model Schematic...................................................................................... 1
Hydrograph Return Period Recap............................................................................. 2
1 -Year
SummaryReport......................................................................................................................... 3
2 - Year
SummaryReport......................................................................................................................... 4
3 - Year
SummaryReport......................................................................................................................... 5
10 -Year
SummaryReport......................................................................................................................... 6
100 - Year
SummaryReport......................................................................................................................... 7
OFReport.................................................................................................................... 8
CUI PN97470 - Page 15 of 58

CUI
1
Watershed Model Schematic Hydraflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk, Inc. v202O.4
{ PRE A.0 (SITE 1) ,?sue PRE B.0 (SITE 2)
3 -PRE (COMBINE�OST A.1 �OST A.2 �OST A.3 �OST B.0
8 - ROUTE TANK
9 - Inflow to SCM (BIOI
10 - ROUTE SCM
Legend
Hid. Origin Description
1
SCS Runoff
PRE A.0 (SITE 1)
2
SCS Runoff
PRE B.0 (SITE 2)
3
Combine
PRE (COMBINED)
4
SCS Runoff
POST A.1
5
SCS Runoff
POST A.2
6
SCS Runoff
POST A.3
7
SCS Runoff
POST B.0 (SITE 2)
8
Reservoir
ROUTE TANK
9
Combine
Inflow to SCM (BIOIRET)
10 Reservoir ROUTE SCM
11 Combine POST A.0 (SITE 1)
12 Combine POST (COMBINED)
11 -POST A.0 (SITE 1)
12 - POST (COMBINED)
2)
Project: JS0C_SWM_Sites_RTA-Rev1.gpw
Thursday, 01 / 26 / 2023

CUI
Hydrograph Return Period RecP�
y raflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk, Inc. v2020.4
Hyd.
Hydrograph
Inflow
Peak Outflow (cfs)
Hydrograph
No.
type
hyd(s)
Description
(origin)
1-yr
2-yr
3-yr
�1-yr
10-yr
25-yr
50-yr
100-yr
1
SCS Runoff
------
0.024
0.184
0.000
-------
1.022
-------
-------
2.913
PRE A.0 (SITE 1)
2
SCS Runoff
------
1.138
1.450
0.531
-------
2.292
-------
-------
3.606
PRE B.0 (SITE 2)
3
Combine
1,2
1.140
1.590
0.531
-------
3.293
-------
-------
6.477
PRE (COMBINED)
4
SCS Runoff
------
0.872
1.081
0.455
-------
1.640
-------
-------
2.515
POST A.1
5
SCS Runoff
------
0.841
1.149
0.288
-------
2.024
-------
-------
3.448
POST A.2
6
SCS Runoff
------
0.315
0.382
0.181
-------
0.564
-------
-------
0.851
POST A.3
7
SCS Runoff
------
0.552
0.793
0.143
-------
1.503
-------
-------
2.690
POST B.0 (SITE 2)
8
Reservoir
4
0.016
0.077
0.000
-------
1.621
-------
-------
2.497
ROUTE TANK
9
Combine
5,8
0.841
1.149
0.288
-------
3.642
-------
-------
5.928
Inflow to SCM (BIOIRET)
10
Reservoir
9
0.032
0.142
0.000
-------
3.207
-------
-------
5.105
ROUTE SCM
11
Combine
6,10
0.315
0.382
0.181
-------
3.674
-------
-------
5.875
POSTA.0 (SITE 1)
12
Combine
7,11
0.863
1.170
0.322
-------
4.984
-------
-------
8.558
POST (COMBINED)
is
3-yr storm
placeholder
for
95th
percentI
le rainfall
results
Proj. file: JS0C_SWM_Sites_RTA-Rev1.gpw
Thursday, 01 / 26 / 2023

Hydrograph Summary Report
CUI
Hydraflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk, Inc. v2020.4
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
0.024
1
723
327
------
------
------
PRE A.0 (SITE 1)
2
SCS Runoff
1.138
1
717
2,377
------
------
------
PRE B.0 (SITE 2)
3
Combine
1.140
1
717
2,704
1,2
------
------
PRE (COMBINED)
4
SCS Runoff
0.872
1
717
1,901
------
------
------
POST A.1
5
SCS Runoff
0.841
1
718
1,689
------
------
------
POST A.2
6
SCS Runoff
0.315
1
717
744
------
------
------
POST A.3
7
SCS Runoff
0.552
1
718
1,114
------
------
------
POST B.0 (SITE 2)
8
Reservoir
0.016
1
950
301
4
268.70
1,602
ROUTE TANK
9
Combine
0.841
1
718
1,990
5,8
------
------
Inflow to SCM (BIOIRET)
10
Reservoir
0.032
1
974
644
9
264.75
1,353
ROUTE SCM
11
Combine
0.315
1
717
1,388
6,10
------
------
POSTA.0 (SITE 1)
12
Combine
0.863
1
718
2,501
7,11
------
------
POST (COMBINED)
JS0C_SWM_Sites_RTA-Rev1.gpw
Return Period: 1 Year
Thursday, 01 / 26 / 2023

Hydrograph Summary Report
CUI
Hydraflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk, Inc. v2020.4
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
0.184
1
720
715
------
------
------
PRE A.0 (SITE 1)
2
SCS Runoff
1.450
1
717
3,070
------
------
------
PRE B.0 (SITE 2)
3
Combine
1.590
1
718
3,784
1,2
------
------
PRE (COMBINED)
4
SCS Runoff
1.081
1
717
2,390
------
------
------
POST A.1
5
SCS Runoff
1.149
1
718
2,323
------
------
------
POST A.2
6
SCS Runoff
0.382
1
717
911
------
------
------
POST A.3
7
SCS Runoff
0.793
1
718
1,593
------
------
------
POST B.0 (SITE 2)
8
Reservoir
0.077
1
751
790
4
268.72
1,608
ROUTE TANK
9
Combine
1.149
1
718
3,113
5,8
------
------
Inflow to SCM (BIOIRET)
10
Reservoir
0.142
1
761
1,767
9
264.77
1,379
ROUTE SCM
11
Combine
0.382
1
717
2,678
6,10
------
------
POSTA.0 (SITE 1)
12
Combine
1.170
1
718
4,270
7,11
------
------
POST (COMBINED)
JS0C_SWM_Sites_RTA-Rev1.gpw
Return Period: 2 Year
Thursday, 01 / 26 / 2023

Hydrograph Summary Report
CUI
Hydraflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk, Inc. v2020.4
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
0.000
1
n/a
0
------
------
------
PRE A.0 (SITE 1)
2
SCS Runoff
0.531
1
718
1,074
------
------
------
PRE B.0 (SITE 2)
3
Combine
0.531
1
718
1,074
1,2
------
------
PRE (COMBINED)
4
SCS Runoff
0.455
1
717
951
------
------
------
POST A.1
5
SCS Runoff
0.288
1
718
595
------
------
------
POST A.2
6
SCS Runoff
0.181
1
717
413
------
------
------
POST A.3
7
SCS Runoff
0.143
1
719
331
------
------
------
POST B.0 (SITE 2)
8
Reservoir
0.000
1
n/a
0
4
267.08
951
ROUTE TANK
9
Combine
0.288
1
718
595
5,8
------
------
Inflow to SCM (BIOIRET)
10
Reservoir
0.000
1
n/a
0
9
264.28
595
ROUTE SCM
11
Combine
0.181
1
717
413
6,10
------
------
POSTA.0 (SITE 1)
12
Combine
0.322
1
718
744
7,11
------
------
POST (COMBINED)
JS0C_SWM_Sites_RTA-Rev1.gpw
Return Period: 3 Year
Thursday, 01 / 26 / 2023

Hydrograph Summary Report
CUI
Hydraflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk, Inc. v2020.4
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
1.022
1
718
2,311
------
------
------
PRE A.0 (SITE 1)
2
SCS Runoff
2.292
1
717
5,003
------
------
------
PRE B.0 (SITE 2)
3
Combine
3.293
1
718
7,314
1,2
------
------
PRE (COMBINED)
4
SCS Runoff
1.640
1
717
3,736
------
------
------
POST A.1
5
SCS Runoff
2.024
1
717
4,183
------
------
------
POSTA.2
6
SCS Runoff
0.564
1
717
1,366
------
------
------
POST A.3
7
SCS Runoff
1.503
1
718
3,051
------
------
------
POST B.0 (SITE 2)
8
Reservoir
1.621
1
718
2,136
4
268.91
1,685
ROUTE TANK
9
Combine
3.642
1
718
6,319
5,8
------
------
Inflow to SCM (BIOIRET)
10
Reservoir
3.207
1
720
4,973
9
264.96
1,714
ROUTE SCM
11
Combine
3.674
1
720
6,339
6,10
------
------
POSTA.0 (SITE 1)
12
Combine
4.984
1
719
9,390
7,11
------
------
POST (COMBINED)
JS0C_SWM_Sites_RTA-Rev1.gpw
Return Period: 10 Year
Thursday, 01 / 26 / 2023

Hydrograph Summary Report
CUI
Hydraflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk, Inc. v2020.4
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
2.913
1
718
5,915
------
------
------
PRE A.0 (SITE 1)
2
SCS Runoff
3.606
1
717
8,126
------
------
------
PRE B.0 (SITE 2)
3
Combine
6.477
1
718
14,041
1,2
------
------
PRE (COMBINED)
4
SCS Runoff
2.515
1
717
5,881
------
------
------
POST A.1
5
SCS Runoff
3.448
1
717
7,327
------
------
------
POST A.2
6
SCS Runoff
0.851
1
717
2,086
------
------
------
POST A.3
7
SCS Runoff
2.690
1
717
5,597
------
------
------
POST B.0 (SITE 2)
8
Reservoir
2.497
1
718
4,281
4
268.98
1,713
ROUTE TANK
9
Combine
5.928
1
717
11,608
5,8
------
------
Inflow to SCM (BIOIRET)
10
Reservoir
5.105
1
720
10,262
9
265.11
2,062
ROUTE SCM
11
Combine
5.875
1
718
12,348
6,10
------
------
POSTA.0 (SITE 1)
12
Combine
8.558
1
718
17,945
7,11
------
------
POST (COMBINED)
JS0C_SWM_Sites_RTA-Rev1.gpw
Return Period: 100 Year
Thursday, 01 / 26 / 2023

Cul $
Hydraflow Rainfall Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Return
Period
Intensity -Duration -Frequency Equation Coefficients (FHA)
(Yrs)
B
D
E
(NIA)
1
0.0000
0.0000
0.0000
--------
2
69.8703
13.1000
0.8658
--------
3
0.0000
0.0000
0.0000
--------
5
79.2597
14.6000
0.8369
--------
10
88.2351
15.5000
0.8279
--------
25
102.6072
16.5000
0.8217
--------
50
114.8193
17.2000
0.8199
--------
100
127.1596
17.8000
0.8186
--------
File name: SampleFHA.idf
Intensity = B / (Tc + D)^E
Thursday, 01 / 26 / 2023
Return
Period
Intensity Values (in/hr)
(Yrs)
5 min
10
15
20
25
30
35
40
45
50
55
60
1
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
2
5.69
4.61
3.89
3.38
2.99
2.69
2.44
2.24
2.07
1.93
1.81
1.70
3
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
5
6.57
5.43
4.65
4.08
3.65
3.30
3.02
2.79
2.59
2.42
2.27
2.15
10
7.24
6.04
5.21
4.59
4.12
3.74
3.43
3.17
2.95
2.77
2.60
2.46
25
8.25
6.95
6.03
5.34
4.80
4.38
4.02
3.73
3.48
3.26
3.07
2.91
50
9.04
7.65
6.66
5.92
5.34
4.87
4.49
4.16
3.88
3.65
3.44
3.25
100
9.83
8.36
7.30
6.50
5.87
5.36
4.94
4.59
4.29
4.03
3.80
3.60
Tc = time in minutes. Values may exceed 60.
)m\60652522\400 Technical\431 Civil\Calculations\Stormwater\Models\Hvdraflow\NC NRCS FortBraaa Atlas-14.oco
Storm
Rainfall Precipitation Table (in)
Distribution
1-yr
2-yr
3-yr
5-yr
10-yr
25-yr
50-yr
100-yr
SCS 24-hour
3.07
3.71
1.80
0.00
5.45
0.00
0.00
8.20
SCS 6-Hr
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-1 st
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-2nd
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-3rd
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-4th
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-Indy
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Custom
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
PN97470 - Page 23 of 58

CUI
10-Year Hydrograph
and Routing Reports I REVISED
CUI PN97470 - Page 24 of 58

CUI
Hydraflow Table of Contents JS0C_SWM_Sites_RTA-Rev1.gpw
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Watershed Model Schematic...................................................................................... 1
10 -Year
HydrographReports................................................................................................................... 2
Hydrograph No.
1, SCS Runoff, PRE A.0 (SITE 1)..................................................................
2
Hydrograph No.
2, SCS Runoff, PRE B.0 (SITE 2)..................................................................
3
Hydrograph No.
3, Combine, PRE (COMBINED)....................................................................
4
Hydrograph No.
4, SCS Runoff, POST A.1..............................................................................
5
Hydrograph No.
5, SCS Runoff, POST A.2..............................................................................
6
Hydrograph No.
6, SCS Runoff, POST A.3..............................................................................
7
Hydrograph No.
7, SCS Runoff, POST B.0 (SITE 2)...............................................................
8
Hydrograph No.
8, Reservoir, ROUTE TANK..........................................................................
9
PondReport
- TANK.........................................................................................................
10
Hydrograph No.
9, Combine, Inflow to SCM(BIOIRET)........................................................
11
Hydrograph No.
10, Reservoir, ROUTE SCM........................................................................
12
PondReport
- SCM-Rev1..................................................................................................
13
Hydrograph No.
11, Combine, POST A.0 (SITE 1)...............................................................
14
Hydrograph No.
12, Combine, POST (COMBINED)..............................................................
15
OFReport.................................................................................................................. 16
CUI PN97470 - Page 25 of 58

CUI
1
Watershed Model Schematic Hydraflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk, Inc. v202O.4
{ PRE A.0 (SITE 1) ,?sue PRE B.0 (SITE 2)
3 -PRE (COMBINE�OST A.1 �OST A.2 �OST A.3 �OST B.0
8 - ROUTE TANK
9 - Inflow to SCM (BIOI
10 - ROUTE SCM
Legend
Hid. Origin Description
1
SCS Runoff
PRE A.0 (SITE 1)
2
SCS Runoff
PRE B.0 (SITE 2)
3
Combine
PRE (COMBINED)
4
SCS Runoff
POST A.1
5
SCS Runoff
POST A.2
6
SCS Runoff
POST A.3
7
SCS Runoff
POST B.0 (SITE 2)
8
Reservoir
ROUTE TANK
9
Combine
Inflow to SCM (BIOIRET)
10 Reservoir ROUTE SCM
11 Combine POST A.0 (SITE 1)
12 Combine POST (COMBINED)
11 -POST A.0 (SITE 1)
12 - POST (COMBINED)
2)
Project: JS0C_SWM_Sites_RTA-Rev1.gpw
Thursday, 01 / 26 / 2023

cul 2
Hydrograph Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 1
PRE A.0 (SITE 1)
Hydrograph type
= SCS Runoff
Peak discharge
= 1.022 cfs
Storm frequency
= 10 yrs
Time to peak
= 11.97 hrs
Time interval
= 1 min
Hyd. volume
= 2,311 cuft
Drainage area
= 0.610 ac
Curve number
= 52
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 6.00 min
Total precip.
= 5.45 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
2.00
1.00
PRE A.0 (SITE 1)
Hyd. No. 1 -- 10 Year
2 4 6 8 10 12 14
Hyd No. 1
Q (cfs)
2.00
1.00
0.00
16 18 20 22 24 26
Time (hrs)
cul PN97470 - Page 27 of 58

Hydrograph
Report
cul
3
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Hyd. No. 2
PRE B.0 (SITE 2)
Hydrograph type = SCS Runoff Peak discharge
Storm frequency = 10 yrs Time to peak
Time interval = 1 min Hyd. volume
Drainage area = 0.310 ac Curve number
Basin Slope = 0.0 % Hydraulic length
Tc method = User Time of conc. (Tc)
Total precip. = 5.45 in Distribution
Storm duration = 24 hrs Shape factor
Thursday, 01 / 26 / 2023
= 2.292 cfs
= 11.95 hrs
= 5,003 cuft
= 90
= 0 ft
= 6.00 min
= Type II
= 484
Q (cfs)
3.00
PRE B.0 (SITE 2)
Hyd. No. 2 -- 10 Year
Q (cfs)
3.00
2.00
2.00
1.00
1.00
0.00
0.0 2.0
Hyd No.
4.0 6.0 8.0 10.0 12.0 14.0 16.0
2
0.00
18.0 20.0
Time (hrs)
cul PN97470 - Page 28 of 58

cul 4
Hydrograph Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 3
PRE (COMBINED)
Hydrograph type
= Combine
Peak discharge
= 3.293 cfs
Storm frequency
= 10 yrs
Time to peak
= 11.97 hrs
Time interval
= 1 min
Hyd. volume
= 7,314 cuft
Inflow hyds.
= 1, 2
Contrib. drain. area
= 0.920 ac
PRE (COMBINED)
Q (cfs) Hyd. No. 3 -- 10 Year Q (cfs)
4.00 4.00
3.00 3.00
2.00 2.00
1.00 1.00
0.00 - 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
— Hyd No. 3 Hyd No. 1 Hyd No. 2 Time (hrs)
CUI PN97470 - Page 29 of 58

cul 5
Hydrograph Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 4
POST A.1
Hydrograph type
= SCS Runoff
Peak discharge
= 1.640 cfs
Storm frequency
= 10 yrs
Time to peak
= 11.95 hrs
Time interval
= 1 min
Hyd. volume
= 3,736 cuft
Drainage area
= 0.210 ac
Curve number
= 94
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 6.00 min
Total precip.
= 5.45 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
2.00
1.00
w
POST A.1
Hyd. No. 4 -- 10 Year
2.0 4.0 6.0 8.0
Hyd No. 4
Q (cfs)
2.00
1.00
10.0 12.0 14.0 16.0 18.0 20.0
Time (hrs)
cul PN97470 - Page 30 of 58

cul 6
Hydrograph Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 5
POST A.2
Hydrograph type
= SCS Runoff
Peak discharge
= 2.024 cfs
Storm frequency
= 10 yrs
Time to peak
= 11.95 hrs
Time interval
= 1 min
Hyd. volume
= 4,183 cuft
Drainage area
= 0.330 ac
Curve number
= 81
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 6.00 min
Total precip.
= 5.45 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
3.00
2.00
1.00
2.0 4.0
Hyd No. 5
6.0 8.0
POST A.2
Hyd. No. 5 -- 10 Year
Q (cfs)
3.00
2.00
1.00
..n•-- , ' I ' 0.00
10.0 12.0 14.0 16.0 18.0 20.0 22.0
Time (hrs)
cul PN97470 - Page 31 of 58

cul 7
Hydrograph Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 6
POST A.3
Hydrograph type
= SCS Runoff
Peak discharge
= 0.564 cfs
Storm frequency
= 10 yrs
Time to peak
= 11.95 hrs
Time interval
= 1 min
Hyd. volume
= 1,366 cuft
Drainage area
= 0.070 ac
Curve number
= 98
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 6.00 min
Total precip.
= 5.45 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
POST A.3
Hyd. No. 6 -- 10 Year
Q (cfs)
MI
MENNEN
0.0
2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0
Hyd No. 6
20.0
Time (hrs)
cul PN97470 - Page 32 of 58

cul 8
Hydrograph Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 7
POST B.0 (SITE 2)
Hydrograph type
= SCS Runoff
Peak discharge
= 1.503 cfs
Storm frequency
= 10 yrs
Time to peak
= 11.97 hrs
Time interval
= 1 min
Hyd. volume
= 3,051 cuft
Drainage area
= 0.280 ac
Curve number
= 76
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 6.00 min
Total precip.
= 5.45 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
2.00
1.00
POST B.0 (SITE 2)
Hyd. No. 7 -- 10 Year
2 4 6 8 10 12 14
Hyd No. 7
Q (cfs)
2.00
1.00
0.00
16 18 20 22 24
Time (hrs)
CUI PN97470 - Page 33 of 58

Hydrograph
cul
Report
9
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 8
ROUTE TANK
Hydrograph type
= Reservoir
Peak discharge
= 1.621 cfs
Storm frequency
= 10 yrs
Time to peak
= 11.97 hrs
Time interval
= 1 min
Hyd. volume
= 2,136 cuft
Inflow hyd. No.
= 4 - POST A.1
Max. Elevation
= 268.91 ft
Reservoir name
= TANK
Max. Storage
= 1,685 cuft
Storage Indication method used
Q (cfs)
2.00
1.00
ROUTE TANK
Hyd. No. 8 -- 10 Year
2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0
Hyd No. 8 Hyd No. 4 ® Total storage used = 1,685 cuft
Q (cfs)
2.00
1.00
0.00
20.0
Time (hrs)
CUI PN97470 - Page 34 of 58

Pond Report
c` l
10
Hydraflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk,
Inc. v2020.4
Thursday, 01 / 26 / 2023
Pond No. 1 - TANK
Pond Data
Trapezoid -Bottom L x W = 25.0 x 16.0 ft, Side slope = 0.00: 1, Bottom elev. = 264.70 ft, Depth = 5.00 ft
Stage / Storage Table
Stage (ft) Elevation (ft)
Contour area (sqft)
Incr. Storage (cuft)
Total storage (cuft)
0.00 264.70
400
0
0
0.50 265.20
400
200
200
1.00 265.70
400
200
400
1.50 266.20
400
200
600
2.00 266.70
400
200
800
2.50 267.20
400
200
1,000
3.00 267.70
400
200
1,200
3.50 268.20
400
200
1,400
4.00 268.70
400
200
1,600
4.50 269.20
400
200
1,800
5.00 269.70
400
200
2,000
Culvert / Orifice Structures
Weir Structures
[A]
[B]
[C]
[PrFRsr]
[A]
[B]
[C]
[D]
Rise (in)
= 12.00
Inactive
Inactive
Inactive
Crest Len (ft) =
4.97
Inactive
Inactive
Inactive
Span (in)
= 12.00
0.00
0.00
0.00
Crest El. (ft) =
268.70
0.00
0.00
0.00
No. Barrels
= 1
0
0
0
WeirCoeff. =
3.33
3.33
3.33
3.33
Invert El. (ft)
= 265.00
0.00
0.00
0.00
Weir Type =
1
---
---
---
Length (ft)
= 40.00
0.00
0.00
0.00
Multi -Stage =
Yes
No
No
No
Slope (%)
= 1.00
0.00
0.00
n/a
N-Value
= .013
.013
.013
n/a
Orifice Coeff.
= 0.60
0.60
0.60
0.60
Exfil.(in/hr) =
0.000 (by
Wet area)
Multi -Stage
= n/a
No
No
No
TW Elev. (ft) =
0.00
Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).
Stage (ft) Stage / Discharge Elev (ft)
5.00
4.00
3.00
2.00
1.00
0 00
269.70
268.70
267.70
266.70
265.70
264.70
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00
Total Q Discharge (cfs)
CUI PN97470 - Page 35 of 58

cul 11
Hydrograph Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 9
Inflow to SCM (BIOIRET)
Hydrograph type =
Combine
Peak discharge
= 3.642 cfs
Storm frequency =
10 yrs
Time to peak
= 11.97 hrs
Time interval =
1 min
Hyd. volume
= 6,319 cuft
Inflow hyds. =
5, 8
Contrib. drain. area
= 0.330 ac
Inflow to SCM (BIOIRET)
Q (cfs) Hyd. No. 9 -- 10 Year Q (cfs)
4.00 4.00
3.00 3.00
2.00 2.00
1.00 1.00
0.00 0.00
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0
— Hyd No. 9 Hyd No. 5 Hyd No. 8 Time (hrs)
cul PN97470 - Page 36 of 58

cul 12
Hydrograph Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 10
ROUTE SCM
Hydrograph type
= Reservoir
Peak discharge
= 3.207 cfs
Storm frequency
= 10 yrs
Time to peak
= 12.00 hrs
Time interval
= 1 min
Hyd. volume
= 4,973 cuft
Inflow hyd. No.
= 9 - Inflow to SCM (BIOIRET)
Max. Elevation
= 264.96 ft
Reservoir name
= SCM-Rev1
Max. Storage
= 1,714 cuft
Storage Indication method used.
ROUTE SCM
Q (cfs) Hyd. No. 10 -- 10 Year Q (cfs)
4.00 4.00
3.00 3.00
2.00 2.00
1.00 1.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24
— Hyd No. 10 Hyd No. 9 ® Total storage used = 1,714 cult Time (hrs)
CUI PN97470 - Page 37 of 58

Pond Report
c` l
13
Hydraflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk,
Inc. v2020.4
Thursday, 01 / 26 / 2023
Pond No. 3 - SCM-Rev1
Pond Data
Contours -User-defined contour areas.
Conic method used for volume
calculation. Begining
Elevation = 263.50 ft
Stage / Storage Table
Stage (ft) Elevation (ft)
Contour area (sqft)
Incr. Storage (cuft)
Total storage (cuft)
0.00 263.50
00
0
0
0.50 264.00
1,262
210
210
1.00 264.50
1,525
696
906
1.50 265.00
2,003
879
1,785
2.00 265.50
3,144
1,276
3,061
2.50 266.00
3,144
1,572
4,633
Culvert / Orifice Structures
Weir Structures
[A]
[B]
[C]
[PrFRsr]
[A]
[B]
[C]
[D]
Rise (in)
= 12.00
0.00
0.00
0.00
Crest Len (ft)
= 10.00
10.00
0.00
0.00
Span (in)
= 12.00
0.00
0.00
0.00
Crest El. (ft)
= 264.75
265.50
0.00
0.00
No. Barrels
= 1
0
0
0
WeirCoeff.
= 3.33
2.60
3.33
3.33
Invert El. (ft)
= 262.40
0.00
0.00
0.00
Weir Type
= 1
Broad
---
---
Length (ft)
= 40.00
0.00
0.00
0.00
Multi -Stage
= Yes
No
No
No
Slope (%)
= 0.50
0.00
0.00
n/a
N-Value
= .013
.013
.013
n/a
Orifice Coeff.
= 0.60
0.60
0.60
0.60
Exfil.(in/hr)
= 0.000 (by
Contour)
Multi -Stage
= n/a
No
No
No
TW Elev. (ft)
= 0.00
Stage (ft)
3.00
08
0.00
0.00 2.00
Total Q
Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).
Stage / Discharge
4.00 6.00 8.00 10.00 12.00 14.00
Elev (ft)
266.50
265.50
264.50
' 263.50
16.00
Discharge (cfs)
CUI PN97470 - Page 38 of 58

cul 14
Hydrograph Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 11
POST A.0 (SITE 1)
Hydrograph type
= Combine
Peak discharge
= 3.674 cfs
Storm frequency
= 10 yrs
Time to peak
= 12.00 hrs
Time interval
= 1 min
Hyd. volume
= 6,339 cuft
Inflow hyds.
= 6, 10
Contrib. drain. area
= 0.070 ac
POST A.0 (SITE 1)
Q (cfs) Hyd. No. 11 -- 10 Year Q (cfs)
4.00 4.00
3.00 3.00
2.00 2.00
1.00 1.00
0.00 - 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24
— Hyd No. 11 Hyd No. 6 Hyd No. 10 Time (hrs)
cul PN97470 - Page 39 of 58

cul 15
Hydrograph Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Thursday, 01 / 26 / 2023
Hyd. No. 12
POST (COMBINED)
Hydrograph type
= Combine
Peak discharge
= 4.984 cfs
Storm frequency
= 10 yrs
Time to peak
= 11.98 hrs
Time interval
= 1 min
Hyd. volume
= 9,390 cuft
Inflow hyds.
= 7, 11
Contrib. drain. area
= 0.280 ac
POST (COMBINED)
Q (cfs) Hyd. No. 12 -- 10 Year Q (cfs)
5.00 5.00
4.00 4.00
3.00 3.00
2.00 2.00
1.00 1.00
0.00 - 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
— Hyd No. 12 Hyd No. 7 Hyd No. 11 Time (hrs)
cul PN97470 - Page 40 of 58

Cul 16
Hydraflow Rainfall Report
Hydraflow Hydrographs Extension for AUtodeskS Civil 3DO by Autodesk, Inc. v2020.4
Return
Period
Intensity -Duration -Frequency Equation Coefficients (FHA)
(Yrs)
B
D
E
(NIA)
1
0.0000
0.0000
0.0000
--------
2
69.8703
13.1000
0.8658
--------
3
0.0000
0.0000
0.0000
--------
5
79.2597
14.6000
0.8369
--------
10
88.2351
15.5000
0.8279
--------
25
102.6072
16.5000
0.8217
--------
50
114.8193
17.2000
0.8199
--------
100
127.1596
17.8000
0.8186
--------
File name: SampleFHA.idf
Intensity = B / (Tc + D)^E
Thursday, 01 / 26 / 2023
Return
Period
Intensity Values (in/hr)
(Yrs)
5 min
10
15
20
25
30
35
40
45
50
55
60
1
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
2
5.69
4.61
3.89
3.38
2.99
2.69
2.44
2.24
2.07
1.93
1.81
1.70
3
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
5
6.57
5.43
4.65
4.08
3.65
3.30
3.02
2.79
2.59
2.42
2.27
2.15
10
7.24
6.04
5.21
4.59
4.12
3.74
3.43
3.17
2.95
2.77
2.60
2.46
25
8.25
6.95
6.03
5.34
4.80
4.38
4.02
3.73
3.48
3.26
3.07
2.91
50
9.04
7.65
6.66
5.92
5.34
4.87
4.49
4.16
3.88
3.65
3.44
3.25
100
9.83
8.36
7.30
6.50
5.87
5.36
4.94
4.59
4.29
4.03
3.80
3.60
Tc = time in minutes. Values may exceed 60.
)m\60652522\400 Technical\431 Civil\Calculations\Stormwater\Models\Hvdraflow\NC NRCS FortBraaa Atlas-14.oco
Storm
Rainfall Precipitation Table (in)
Distribution
1-yr
2-yr
3-yr
5-yr
10-yr
25-yr
50-yr
100-yr
SCS 24-hour
3.07
3.71
1.80
0.00
5.45
0.00
0.00
8.20
SCS 6-Hr
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-1 st
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-2nd
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-3rd
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-4th
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-Indy
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Custom
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
PN97470 - Page 41 of 58

CUI
NOAA Atlas-14 Rainfall Data
CUI PN97470 - Page 42 of 58

NOAA Atlas 14, Volume 2, Version 3
Location name: F ragg, North Carolina, USA*'�
Latitude: 35., Longitude:-79.3504°
3
Elevation: 419.14 ft**
`source: ESRI Maps_
''^x�,
"'source: USGS
,...s'
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)
1
2
5
10
25
50
100
200
500
1000
0.439
0.519
0.604
0.667
0.740
0.793
0.843
0.889
0.944
0.987
5-min
(0.399-0.485)
(0.472-0.573)
(0.549-0.667)
(0.605-0.735)
(D.669-0.815)
(0.714-0.872)
(0.755-0.926)
(0.792-0.976)
(0.834-1.04)
(0.865-1.09)
0.701
0.829
0.967
1.07
1.18
1.26
1.34
1.41
1.49
1.55
10-min
(0.638-0.775)
(0.755-0.917)
(0.878-1.07)
(0.967-1.18)
( 1.07-1.3D)
(1.14-1.39)
(1.20-1.47) 11
1.26-1.55)
(1.32-1.64)
( 1.36-1.71)
0.876
1.04
1.22
1.35
1.50
1.60
1.69
1.78
1.88
1.95
15-min
(0.797-0.968)
(0.949-1.15)
1 (1.11-1.35)
1 (1.22-1.49)
1 (1.35-1.65)
1 (1.44-1.76)
1 (1.52-1.86) 11
(1.58-1.95)
(1.66-2.07)
(1.71-2.15)
1.20
1.44
1.74
1.95
2.22
2.41
2.59
2.77
2.99
3.16
30-min
1
( .09-1.33)
(1.31-1.59)
(1.58-1.92)
(1.77-2.15)
(2.00-2.44)
(2.17-2.65)
(2.32-2.85)
(2.47-3.04)
(2.64-3.29)
(2.77-3.47)
1.50
1.81
2.23
2.54
2.95
3.27
3.57
3.88
4.29
4.61
60-min
(1 .36-1.66)
(1.65-2.00)
(2.02-2.46)
(2.31-2.80)
(2.66-3.25)
(2.94-3.59)
(3.20-3.93)
(3.46-4.26)
(3.794.72)
( 4.D4-5.07)
1.76
2.13
2.66
3.07
3.61
4.03
4.46
4.89
5.47
5.92
2-hr
1
( .59-1.96)
(1.93-2.37)
(2.40-2.97)
(2.77-3.42)
(3.23-4.02)
(3.60-4.49)
(3.95-4.96)
(4.31-5.43)
( 4.77-6.08)
(5.12-6.59)
3-hr
1.68-62608
2.04 2552
2.56-3316
2.96 3066
3.50135
3.93 4191
4. 65348
4.80 6008
5.40 6392
5.87-67459
6.63
6-hr
2.01 2.46
2.44-62097
3.06 3?73
3. 54 34
4.216.17
4.73 5185
5. 6 6555
5.81-7.29
6.56 8832
7. 4 9417
2.
4.
9.
12-hr
2.372�90
2.87 3051
3.62D .44
4. 26819
5.03 6321
5. 9-47 07
6.36 7496
7.06 8?92
8.02-310.3
8.78-141.4
3.07
3.71
4.68
5.45
6.50
7.34
8.20
9.10
10.3
11.3
24-hr
(2.85-3.33)
(3.444.03)
(4.33-5.08)
(5.03-5.90)
(5.98-7.04)
(6.73-7.94)
(7.50-8.87) 11
(8.30-9.83)
(9.38-11.2)
(10.2-12.2)
3.58
4.31
5.40
6.26
7.43
8.37
9.33
10.3
11.7
12.8
2-day
(3.32-3.86)
(4.014.65)
(5.01-5.82)
(5.80-6.74)
1 (6.86-8.00)
(7.70-9.01)
(8.57-10.0) 11
(9.44-11.1)
(10.6-12.6)
(11.6-13.8)
3.79
4.57
5.68
6.57
7.78
8.75
9.74
10.8
12.2
13.3
3-day
(3.54-4.07)
(4.264.90)
(5.29-6.10)
(6.11-7.04)
(7.21-8.34)
(8.08-9.38)
1 (8.97-10.5)
(9.88-11.6)
(11.1-13.1)
(12.1-14.3)
4.01
4.82
5.97
6.88
8.14
9.13
10.2
11.2
12.7
13.8
4-day
(3.75-4.29)
(4.51-5.16)
(5.58-6.38)
(6.42-7.34)
(7.56-8.69)
(8.46-9.75)
1 (9.38-10.9)
1 (10.3-12.0)
(11.6-13.6)
(12.6-14.8)
12
4.1
7-day
3
4 33 4496
5. 85493
6. 7025
7.23 8030
8.47-9.74
9.44-10.9
10.4- 2.1
11 5-13.3
12.18-15.0
13 9516.3
5.3064
619417
10-day
5.
5.9.12
7.88209
8.11.3
9.37o1D.6
10.4-11.8
113�13.0
1213-14.1
1317415.8
1417617.0
0.
17618.8
20-day
2.3
6.7.1457
7.98 8495
9.4 D.6
10.6 ,2.9
1212.1 7
131415.0
1415-16.4
155.5
1713 19.8
18 50
30-day
8 8 9738
9.88- 1.1
115�12.9
12.18-14.3
14.4-16.2
15.17---17.6
16.19-19.1
18.11 0.5
19.7 2.5
21 0-24.0
11.2
13.2
15.1
16.6
18.5
20.0
21.4
22.8
24.6
26.0
45-day
(10.6-11.9) 11
(12.5-13.9) 11
(14.3-15.9)
(15.7-17.5)
(17.5-19.5)
(18.8-21.1)
(20.1-22.6)
1 (21.4-24.1)
(23.1-26.1)
(24.3-27.6)
13.4
15.7
17.9
19.5
21.6
23.2
24.7
26.2
28.1
29.6
60-day
(12.8-14.2)
(14.9-16.6)
(16.9-18.8)
(18.5-20.5)
(20.4-22.7)
(21.9-24.4)
(23.3-26.0)
(24.7-27.6)
(26.4-29.7)
(27.7-31.3)
t 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.
Back to Top
PF graphical
CUI PN97470 - Page 43 of 58

NOAA Atlas 14, Volume 2, Version 3
Location name: F ragg, North Carolina, USA*'�
Latitude: 35., Longitude:-79.3504°
3
Elevation: 419.14 ft**
`source: ESRI Maps_
''^x�,
"'source: USGS
,...s'
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 incheslhour)1
Average
recurrence interval (years)
1
2
5
10
25
50
100
200
500
1000
5.27
6.23
7.25
8.00
8.88
9.52
10.1
10.7
11.3
11.8
5-min
(4.79-5.82)
(5.66-6.88)
(6.59-8.00)
(7.26-8.82)
(8.03-9.78)
(8.57-10.5)
(9.06-11.1)
(9.50-11.7)
( 10.0-12.5)
10.4-13.0)
4.21
4.97
5.80
6.40
7.08
7.58
8.04
8.45
8.96
9.32
10-min
(3.83-4.65)
(4.53-5.50)
(5.27-6.41)
(5.80-7.05)
(6.40-7.79)
(6.83-8.33)
(7.20-8.83)
(7.54-9.29)
( 7.91-9.85)
(8.17-10.3)
3.50
4.17
4.89
5.39
5.98
6.40
6.78
7.11
7.52
7.80
15-min
(3.19-3.87)
(3.80-4.61)
(4.44-5.40)
(4.89-5.94)
(5.40-6.58)
(5.76-7.04)
(6.07-7.44)
(6.34-7.81)
(6.64-8.26)
(6.84-8.58)
2.40
2.88
3.47
3.91
4.43
4.82
5.19
5.53
5.98
6.32
30-min
(2.19-2.65)
(2.62-3.18)
(3.16-3.84)
(3.55-4.31)
(4.00-4.88)
(4.34-5.30)
(4.65-5.70)
(4.93-6.08)
(5.28-6.57)
(5.54-6.95)
1.50
1.81
2.23
2.54
2.95
3.27
3.57
3.88
4.29
4.61
60-min
(1 .36-1.66)
(1.65-2.00)
(2.02-2.46)
(2.31-2.80)
(2.66-3.25)
(2.94-3.59)
(3.20-3.93)
(3.46-4.26)
(3.79-4.72)
4.04-5.07)
0.878
1.06
1.33
1.53
1.81
2.02
2.23
2.44
2.73
2.96
2-hr
(0.794-0.980)
(0.962-1.19)
1 (1.20-1.48)
1 (1.38-1.71) 11
(1.62-2.01)
1 (1.80-2.24)
(1.98-2.48)
(2.15-2.72)
(2.39-3.04)
(2.56-3.29)
1.09
1.8
3-hr
0.560-0 691
0.6778--0 837
0.8594105
0.987---11.22
1.17-31a45
1.31-41764
1.45-61482
1.60--2?02
1. 00.30
1.95 2853
1g3953
6-hr
0.336-04 11
0.407---0 496
0.511-0 623
0.592--0..725
0.703-0 864
0.790-0 977
0.879--11.09
0.970-1.22
1.10-21.39
1
67
0.532
12-hr
0.197-0.241
0.238-0.292
0.300--0 368
0.350-0430
0.4D18-0516
0.4772-0586
0.5228-0 661
0.586-0. 40
0.666-0 854
.863
0.728-0 946
0.128
0.155
0.195
0.227
0.271
0.306
0.342
0.379
0.430
0.471
24-hr
(0.119-0.139)
(0.143-0.168)
(0.181-0.212)
(0.209-0.246)
(0.249-0.293)
(0.281-0.331)
(0.313-0.370)
(0.346-0.410)
(0.391-0.465)
(0.426-0.509)
0.074
0.090
0.112
0.130
0.155
0.174
0.194
0.215
0.243
0.266
2-day
(0.069-0.080)
(0.084-0.097)
(0.104-0.121)
(0.121-0.140)
(0.143-0.167)
(0.160-0.188)
(0.178-0.209)
(0.197-0.232)
(0.222-0.263)
(0.241-0.287)
0.053
0.063
0.079
0.091
0.108
D.122
0.135
D.150
0.169
0.184
3-day
(0.049-0.057)
(0.059-0.068)
(0.074-0.085)
(0.085-0.098)
(0.100-0.116)
(0.112-0.130)
(0.125-0.145)
(0.137-0.161)
(0.154-0.182)
(0.168-0.199)
0.042
0.050
0.062
0.072
0.085
1.095
0.106
0.117
0.132
0.144
4-day
(0.039-0.045)
(0.047-0.054)
(0.058-0.066)
(0.067-0.076)
(0.079-0.090)
(0.088-0.102)
(0.098-0.113)
(0.108-0.125)
(0.121-0.141)
(0.131-0.154)
0.021
7-day
0.026-0 030
0.031 0 035
0.038-0043
0. 4 -0 049
0.050-0 058
0.056-0065
006 -0 072
D. 68-D 079
0.076-0 089
0. 8 -0 097
10-day
.142
0.021--0 024
0.02 -0 028
0.030-0034
0.03 -0 038
0.039-0 044
0.043-D 049
0047--0 054
0.051 D 059
0.057--0 066
0. 61--0 071
021
123
1.127
1.14
20-115
day
0.014-0 016
0.017--0 019
0.020-0022
0.02 -0 025
0. 0028
0.028-0031
0.03 0-0 034
0.033-D 037
0.036-0 041
0.039-0 044
0.112
30-day
.121
0.01 -0 013
0.014-0 015
0.016-0018
0.018-002D
0.020-0 022
0.02 -0 024
0.023--0 026
0.025-D 028
0.027--0 031
0.029-0 033
0.01D
0.012
0.014
0.015
0.017
1.018
0.020
1.021
0.023
0.024
45-day
(0.010-0.011)
(0.012-0.013)
(0.013-0.015)
(0.015-0.016)
(0.016-0.018)
(0.017-0.020)
(0.019-0.021)
(0.020-0.022)
(0.021-0.024)
(0.023-0.026)
0.009
O.D11
0.012
0.014
0.015
0.016
0.017
D.018
0.020
0.021
60-day
(0.009-0.010)
(0.010-D.D11)
(0.012-0.013)
(O.D13-D.014)
(0.014-0.016)
(0.015-0.017)
(0.016-0.018)
(0.017-D.D19)
(0.018-0.021)
(0.019-0.022)
frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
rsinparenthesis are PF estimates at lower and upper hounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a
EP,.�afn,121,on
uration 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
dagainst probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
fer to NOAA Atlas 14 document for more information.
Back to Top
PF graphical
CUI PN97470 - Page 44 of 58

CUI
Bioretention SCM
Underdrain Calculations
CUI PN97470 - Page 45 of 58

cul
NCDEQ Stormwater Design Manual
0 Environmental
Quality
When an impoundment is located in karst topography, gravelly sands, or
fractured bedrock, a liner may be needed to sustain a permanent pool of water. If
geotechnical tests confirm the need for a liner, acceptable options can include: 6
to 12 inches of clay soil (minimum 15 percent passing the #200 sieve and a
maximum permeability of 1 x 10-5 cm/sec), a 30 mil poly -liner, or a bentonite
liner.
Underdrain Systems
Underdrain systems are utilized in several SCM designs, and can have many different
configurations. The underdrain system will either daylight, connect to another SCM, or connect
to the conveyance system. All piping within the underdrain system should have a minimum
slope of 0.5 percent and should be constructed of Schedule 40 or SDR 35 smooth wall PVC
pipe. The underdrain pipes should be designed to carry 2-10 times the maximum flow exfiltrating
from the SCM medium. Choose a value within this range to reflect the expected stability of the
drainage area. This maximum flow is computed from Darcy's law and assuming maximum
ponding and complete saturation along the depth of the medium. Manning's formula is then used
to size the pipe. Due to the risk of underdrain clogging, designers are encouraged to install more
than one underdrain of smaller diameter in order to facilitate drainage. The minimum size of pipe
should be 4-inch diameter. The spacing of collection laterals should be no greater than 10 feet
center to center, and a minimum of two pipes should be installed to allow for redundancy (Hunt
and White, 2001). A minimum of 4 rows of perforations should be provided around the diameter
of the pipe (more for pipes 10 inches in diameter and larger), and the perforations should be
placed 6 inches on center within each row for the entire length of the drainage lateral.
Perforations should be 3/8-inch in diameter.
The underdrain pipes should have a minimum of 3 inches of washed #57 stone above and on
each side of the pipe (stone is not required below the pipe). Above the stone, either filter fabric or
two inches of choking stone is recommended to protect the underdrain from blockage. Avoid filter
fabric if there is any question about the future stability of the drainage area. Above the filtering
device, a minimum of 2 inches of washed sand should be installed. Choking stone (#8 or #89) in
lieu of filter fabric is recommended if there is potential for higher sediment loads that would lead
to clogging. Pipe socks are also not recommended.
Typically, bioretention SCMs in the Piedmont region of North Carolina will require underdrains
with an up -turned elbow.
The number of pipes needed for the underdrain system can be determined using the following 3-
step process:
1. Determine flow rate through the soil media and apply a safety factor of 10 (this is now
the underdrain design flow, Q).
2. Use Equation 1 below
FILTER MEDIA SURFACE AREA —1260 SF
6 i n/h r = 0.5 ft/h r ... 0.5* 1260 / 3600 = 0.175 cfs x 10 = 1.75 cfs
2 i n/h r = 0.16 ft/h r ... 0.16* 1260 / 3600 = 0.056 cfs x 10 = 0.56 cfs
A-5. Common SCM Structures & Materials 12 Revised: 2-11-2018
cul PN97470 - Page 46 of 58

NCDEQ Stormwater Design Manual
cul
En vironmental
Quality
Equation 1: Underdrain Pipe Size
(3) for 6 in/hr (MAX): Q = 1.75 cfs --> D = 9.82 inches
8 for 4 in/hr: Q = 1.16 cfs --> D = 8.41 inches
D = 16 So.s for 3 in/hr: Q = 0.88 cfs --> D = 7.57 inches
for 2 in/hr (MIN): Q = 0.56 cfs --> D = 6.41 inches
where: D = Diameter of single pipe (inches)
n = Roughness factor (recommended to be 0.011)
S = Internal slope (recommended to be 0.5%)
Q = Underdrain design flow (cfs)
3. The only unknown is D. This is the diameter of a single pipe that could carry all the water
were it to be the only underdrain. Underdrain pipe diameters are typically either 4 inches
or 6 inches. Table 1 and 2 below convert D (in inches) to an equal number of 4 or 6 inch
underdrains at 0.5% slope.
Table 1: Number of 4" Pipes Required in the Underdrain
5.13 2
5.95 3
4 - 4" underdrains to
6.66 4 handle a media infiltration
rate of u p to 2 in/hr.
7.22 5
7.75 6
8.20 7
Table 2: Number of 6" Pipes Required in the Underdrain
ff ' is Less Than No. of 6" Pipes 2 - 6" underdrains to
7.84 2 handle a media infiltration
rate up to 3 in/hr.
9.11 3
4 - 6" underdrains to
10.13 4 handle a media infiltration
rate of up to 6 in/hr.
A-5. Common SCM Structures & Materials 13
Revised: 2-11-2018
SUMMARY: Selecting underdrains for 3 in/hr (nominal) target.
USE two 6-inch underdrains connected to one 8-inch underdrain manifold. Turn up manifold with
90d elbows to set the internal water storage�IWS) depth as shown on drawings. PN97470 - Paae 47 of

cul
NCDEQ Stormwater Design Manual
Environmental
Quality
R
i ill
4
C
P_ I
Outlets of SCMs are the devices that control the flow of stormwater out of the SCM to the
conveyance system (stormwater pipe, natural drainageway, etc.). While most of the water
quality treatment takes place within the SCM, the outlet design is often integral to treatment
efficiency, as well as being a critical factor in stormwater volume control.
Water quality is affected by how quickly the water is removed from the treatment unit, thereby
affecting sedimentation time and possibly causing resuspension of particles.
The depth from which the water is drawn also affects water quality, since the water is typically
cleaner the higher it is in the water column. Finally, the design of the outlet is also the main
means of controlling peak flow volumes and rates. Outlet designs are specific for each SCM
depending on the goals to be achieved. The following sections will discuss many of the most
common outlet designs. Hydraulic calculations for outlets types as well as storage and
drawdowns are provided in Part B, Calculation Guidance. It should be noted that floatation
issues should be considered with any structure (outlet box, riser, etc.) placed within a SCM.
Designers should consider including provisions such as adjustable weirs to regulate and
optimize water surface elevations and bottom drains and valves to allow the SCM to be drained
for repairs and maintenance
A drawdown orifice should have a turned -down elbow or other safeguard in order to prevent
trash or other material floating on the surface from clogging the pipe. An example is shown in
Figure 5.
A-5. Common SCM Structures & Materials 14 Revised: 2-11-2018
cul PN97470 - Page 48 of 58

CUI
Erosion & Sediment Control
Outlet Protection
CUI PN97470 - Page 49 of 58

Channel Report
Hydraflow Express Extension for AUtodeskS Civil 3DO by Autodesk, Inc. Tuesday, Sep 6 2022
OVERFLOW FROM CONTAINMENT TO BIORETENTION (OP-1)
Circular
Highlighted
Diameter (ft)
= 1.00
Depth (ft)
= 0.58
Q (cfs)
= 1.600
Area (sqft)
= 0.47
Invert Elev (ft)
= 264.00
Velocity (ft/s)
= 3.38
Slope (%)
= 0.50
Wetted Perim (ft)
= 1.73
N-Value
= 0.013
Crit Depth, Yc (ft)
= 0.54
Top Width (ft)
= 0.99
Calculations
EGL (ft)
= 0.76
Compute by:
Known Q
Known Q (cfs)
= 1.60
Elev (ft) Section Depth (ft)
266.00 2.00
265.50 1.50
265.00 1.00
gyp
264.50 - 0.50
264.00 0.00
263.50 -0.50
0 1 2 3
CUI Reach (ft) PN97470 - Page 50 of 58

cul
Depth
Q
Area
Veloc
wp
(ft)
(cfs)
(sgft)
(ft/s)
(ft)
0.10
0.053
0.041
1.29
0.64
0.20
0.223
0.113
1.98
0.93
0.30
0.494
0.198
2.49
1.16
0.40
0.850
0.294
2.89
1.37
0.50
1.268
0.395
3.21
1.57
0.60
1.698
0.493
3.44
1.77
0.70
2.113
0.588
3.59
1.98
0.80
2.462
0.674
3.65
2.22
0.90
2.685
0.745
3.60
2.50
1.00
2.518
0.785
3.21
3.14
Hydraflow Express - OVERFLOW FROM CONTAINMENT TO BIORETENTION (OP-1) - 09/6/22 1
cul PN97470 - Page 51 of 58

cul
Yc
TopWidth
Energy
(ft)
(ft)
(ft)
0.10
0.60
0.13
0.20
0.80
0.26
0.30
0.92
0.40
0.39
0.98
0.53
0.48
1.00
0.66
0.56
0.98
0.78
0.63
0.92
0.90
0.68
0.80
1.01
0.71
0.60
1.10
0.68
0.00
1.16
Hydraflow Express - OVERFLOW FROM CONTAINMENT TO BIORETENTION (OP-1) - 09/6/22 2
cul PN97470 - Page 52 of 58

Channel Report
Hydraflow Express Extension for AUtodeskS Civil 31DO by Autodesk, Inc.
BIORETENTION
OUTFALL (OP-2)
Circular
Diameter (ft)
= 1.00
Invert Elev (ft)
= 262.40
Slope (%)
= 0.50
N-Value
= 0.013
Calculations
Compute by:
Known Q
Known Q (cfs)
= 1.90
Elev (ft)
264.00
263.50
263.00
262.50
262.00
261.50
Tuesday, Sep 6 2022
Highlighted
Depth (ft)
= 0.65
Q (cfs)
= 1.900
Area (sqft)
= 0.54
Velocity (ft/s)
= 3.50
Wetted Perim (ft)
= 1.88
Crit Depth, Yc (ft)
= 0.59
Top Width (ft)
= 0.95
EGL (ft)
= 0.84
Section
Depth (ft)
.60
1.10
0.10
-0.40
1 1 -0.90
1 2 3
CUI Reach (ft) PN97470 - Page 53 of 58

cul
Depth
Q
Area
Veloc
Wp
(ft)
(cfs)
(sgft)
(ft/s)
(ft)
0.10
0.053
0.041
1.29
0.64
0.20
0.223
0.113
1.98
0.93
0.30
0.494
0.198
2.49
1.16
0.40
0.850
0.294
2.89
1.37
0.50
1.268
0.395
3.21
1.57
0.60
1.698
0.493
3.44
1.77
0.70
2.113
0.588
3.59
1.98
0.80
2.462
0.674
3.65
2.22
0.90
2.685
0.745
3.60
2.50
1.00
2.518
0.785
3.21
3.14
Hydraflow Express - BIORETENTION OUTFALL (OP-2) - 09/6/22 1
cul PN97470 - Page 54 of 58

cul
Yc
Topwidth
Energy
(ft)
(ft)
(ft)
0.10
0.60
0.13
0.20
0.80
0.26
0.30
0.92
0.40
0.39
0.98
0.53
0.48
1.00
0.66
0.56
0.98
0.78
0.63
0.92
0.90
0.68
0.80
1.01
0.71
0.60
1.10
0.68
0.00
1.16
Hydraflow Express - BIORETENTION OUTFALL (OP-2) - 09/6/22 2
cul PN97470 - Page 55 of 58

Culvert Report
Hydraflow Express Extension for AUtodeskS Civil 3DO by Autodesk, Inc. Thursday, Jan 26 2023
BIORET OUTFALL TO OP-2 (10-YR) I REVISED
Invert Elev Dn (ft)
= 262.20
Calculations
Pipe Length (ft)
= 40.00
Qmin (cfs)
= 1.00
Slope (%)
= 0.50
Qmax (cfs)
= 4.00
Invert Elev Up (ft)
= 262.40
Tailwater Elev (ft)
_ (dc+D)/2
Rise (in)
= 12.0
Shape
= Circular
Highlighted
Span (in)
= 12.0
Qtotal (cfs)
= 3.30
No. Barrels
= 1
Qpipe (cfs)
= 3.30
n-Value
= 0.013
Qovertop (cfs)
= 0.00
Culvert Type
= Circular Concrete
Veloc Dn (ft/s)
= 4.47
Culvert Entrance
= Square edge w/headwall (C)
Veloc Up (ft/s)
= 4.20
Coeff. K,M,c,Y,k
= 0.0098, 2, 0.0398, 0.67, 0.5
HGL Dn (ft)
= 263.09
HGL Up (ft)
= 263.45
Embankment
Hw Elev (ft)
= 263.77
Top Elevation (ft)
= 265.23
Hw/D (ft)
= 1.37
Top Width (ft)
= 5.00
Flow Regime
= Inlet Control
Crest Width (ft)
= 10.00
Ele (ft)
26600
265.OD
264.00
20.00
262 0D
261.OD
c Name>
Circular Culvert HGL Embank
Hw Depth (R)
360
2.60
1.60
0.60
-0 40
-1.40
Reach (R)
Cul
PN97470 - Page 56 of 58

cul
REVISED0 (OP-1)
..
..
OALa = ,
E
'
D- 6
(using
0 '
� -
s
�.USE
NCDOT...
1
I1
i
.
I
'1911
ii'
a
�
r
•
•
���
��
II
III 'a���
'��
I'
I.
►_
NMI
�
ii
�
rNN��rl�
rtr
•
�
�
,�
��
��
��
,
.�
■off®iI�I�
iR'�i�;
I�
�
•
JI
lm
�
�0.0
�
E
I
.��wm.�erwrwrnrw�w����ftifti������� ���1111� rlr rrl 1
Curves may not be extrapolated.
Figure 8.06b Design of outlet pr❑teation from a round pipe flowing full, maximum tailwater condition (Tw? 0.5 diameter).
CONTAINMENT TANK TO 13IORETENTION BASIN (OP-1)
12" DUCTILE IRON PIPE @ 0.5% SLOPE
Q10 = 1.6 cfs (from 10-yr reservoir
V10 = 3.4 fps
Qfull = 2.7 cfs (full discharge, gravity flow only)
Vfull = 3.7 fps (full velocity, gravity flow only)
8.06.4 Rev. 12/93
cul PN97470 - Page 57 of 58

cul
REVISED (OP-2)
Outlet W = Do + O.4La
pipe
diameter (Ors) La
Tailw ter 5136
30
20
.i
10
USE
minimum 0
3 5
50 100
Discharge (P/sec)
Curves may not be extrapolated.
Figure 8.06b Design of outlet pr❑teation from a round pipe flowing full, maximum tailwater condition (Tw? 0-5 diameter).
13IORETENTION BASIN OUTFALL (OP-2)
12" DIP @ 0.5% SLOPE
Q10 = 3.3 cfs (from 10-yr reservoir routing output)
V10 = 4.2 fps (from continuity)
Qfull = 2.7 cfs (full discharge, gravity flow only)
Vfull = 3.7 fps (full velocity, gravity flow only)
8.06.4 Rev. 12/93
PN97470 - Page 58 of 58
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