SW8160501_Historical File_20200303

LEGEND:
bS - EXISTING IRON STAKE
SIS - SET, IRON STAKE
EIP = EXISTING [RON PIPE
EC-M = EXtSITNG CONCRETE MONUMENT
CC = CONTROL CORNER
EPK = EXISTING PIK RAIL
SPK = SET PK NAIL
ENI> = EXISTING NAIL
(em) = BENCHMARK
R/W = RIGHT OF WAY
EOP = EDGE OF PAVEMENT
MBL - MINIMUM BUILDING LINE
BOC = BACK OF CURB
CO = SANITARY SEWER CLEAN -OUT
WM = WATER METER
P I P I = POWER. POLE
LP = LIGHT POLE
PPT = POWER POIF WITH, TRANSFORMER
SL* = SECURITY LIGHT
GW = GUY "RE
CS = CATCH aASIN
DI = DROP INLET
JB: = JUNCTION BOX
RCP = REINFORCED CONCRETE PIPE
CMP = CORRUGATED METAL PIPE
INV = IN-VERT
,FES = FLARED FN& SECTION (PIPE)
AC� = ACR'E(S,)
SF = SQUARE FEET
EB - ELECTRIC BOX'
04w= WATER VALNA�
04,w = IRRIGATION VALVE
FOC = FIBER OPTIC CABLE BOX
TLB, TRAFFIC, LIGHT BOX
T13 TELEPHONE BOX
NTS NOT, TO SCALE
MW K40NITORING WELL
N/F NOW OR FORMERLY
5SMH-1 SANITARY SEW'R, MANHOLE
D&UE DRAINAGE & UTILITY EASEMENT
DU&AE DRAINAGE, UTILITY, & ACCESS EASEMENT
LIE UTILITY EASEMENT
FF FINISH FLOOR
DEEO >SOOK,, PAGE
D.B., PG­
M.S., PG�= MAP. BOOK, PAGE
--UT-- = UNDERGROUND. TELEPHONE LINE
--UE-- = UNDERGROUND ELECTRICAL LINE
--E-- = OVERHEAO OOWERUNE
_UG_ = UNDERGROUND GAS
- Ts- = OVERHEAD TRAFFIC SIGNAL
-FO- UNDERGROUND- FIBER, OPTIC CABLE
-0-0- 4' CHAIN -LINK FENCE
-0-Cl- 6' WOOD FENCE
-SF- SILT FENCE
�; FIRE HYDRANT
Okpp POWER POLE
LIP LIGHT, POLE
SANITARY SEWER MANHOLE
HC HANDICAP
HCPS HANDICAP PARKING SIGN
HANDICAP PARKING. SPACE
HANDICAP RAMP
PAINTED STOP BAR
STOP
8 = STOP SIGN
nll=untlnllm = GRADING LIMITS LINE SILT FENCE LINE
CPS = COMPACT PARKING SPACE
PROPOSED TRAFFtCfL,0W
EXISTING TRAFFIC FLOW
*SBCF - STEEL SOLLARD WITH� CONCRETE FILL
INT. DOO = INTERIOR LANDSCAPING
EXT. 000 = EXTERIOR LANDSCAPING
+17.47 = EXISTING SPOT ELEVATION
= PROPOSED GRADE
= MATCH EXIS11NG GRADE
= PROPOSED r.RADE AT TOP OF CURB
= PROPOSED GRADE ATTOP OF WALK
06L = DRAINAGE BREAK LINE
= DOUBLE CONCRETE BLOCK FILTER
= FLARED END SECTION
VIC[NITY SKETCH
NOT TO SCALE
+
CONC. LEVEL SPREADER
#
TOP=33t47
+ 32,40
IN-V=XX.XX
+ 32.55 EDGE OF WA TER
2
+ 32,34 +
\1 32t5l PSI.
+
STORM MH
30 4- 3263 32.32 TOP=31-20
EDGE
0 F
ATER N
N�- 2% 5
4
4� 4\,
+ '16,�4
9i A + 300
+
_'\-29,94
+ + 32.36 14331
190
"N'
32,27
+
+ 1,9136
29-91
+ 32�30
j 18,90
+ 32;to + 3?_38
1 7 0,4
16
3p 58 14 1--"
+ +29,96---
32,3!____- 29,70 3atea
3262
+
2", 917A
+ 33,51
32-20
2.9 1 49
­'Mia-t 2
- 30 28 25
429.76
+
+ 12.07
DAAld I
A ),W
38.88 + 3251 294
+25. 1
- - - - - - - - - - + 28.64)
<9 +
25 32�4
z
+ 12,33
*32ZG
29-43
v
.4sy a 20
29.87
42 28-14
32�49 \ \ \ \ - j I STORM MH
9,56 TOP-z��t.'12
1 1, 1 t 13-p It,
+ M93 11 1 k � 30.
I I � 32,50
+ 11-6,; 1 t I \ I \1 .
7 3
19 98 1 1-)
I 1 1 j I I I I 1�1 .1 11
A
I 1 1 4- �Si�4
+ 18.70 fe "I
9198
J,
/4�?.52 .0. ea, 9.95
7t It +4 3 32 + 32.43
+ 32-44
4 - 3-R.rr
+ 2,�
29.6i /4+ 12.37 + a
J 1 +32-39
+ M83 + 32,�6
32
4- 32,31
\t 28.4
-U.97
23. + 20 X
TOP= 30.9 7
L
+ +1
7
ipl. $ / I + < + OUTLET STRUCTURE
29-81
i4llt -
4� 0,
R
INV OUT (18-RCP)=29.03
+
32.51. 19.9 32.tg
+
9.791 4,38
4f7
11 %
+ 312 39
4., 2,41 nge
\3 46tN 1644
1262
9 5 5 +
3216
32.25---� 14,7
k 31.06
.�4
32.29 31 RIP -RAP
4+ 3V57
2 G7-
32,09 43:3 TYPICAL
?G 0
+
2 293
840 at. 3 1 3t.74
4%:-
127,
CS 30�99
1 1'5 4
32,09
30
32 ts 16 101 +
9.99 9�90 2%89
%
32.14
3226
31. 89
27731 3t, 1. 29,87
+ + 32.16 0.95
+
It'93
30 �2814_ 29.� 32,19
7+ 32.46
7,79
32
32,09 /* ag,
2P.496�
4-
5 19 :31
L
32,21
Trosh Rack +31,96 moo
+ 32,50
0=30-97
NOT TO SCALE

7179-00 - Swansboro Walmart Supercenter
Stormwater As -Built Technical Memorandum
Date: February 27, 2020
Re: 7179-00 Swansboro Walmart Supercenter — Driveway Extension
W. Corbett Ave
Swansboro, NC 28584
Onslow County
Project #: NCC138078
Stormwater As -Built Analysis:
Temporary (WQV) Storage Analysis (from WQ orifice to next available outlet):
Required per approved calculations/plans:
Pond 1 = 109,216 cf (including 9,134 cf from off -site)
Pond 2 = 24,075 cf
Pond 3 = 30,416 cf
Provided per as -built survey:
Pond 1 = 109,755 cf (at 31.01')
Pond 2 = 29,445 cf (at 31.19')
Pond 3 = 32,486 cf (at 31.12')
As -Built drawdown should match design, since orifice sizes match design.
Total Pond Volume Above Permanent Pool Provided (and per approved calculations/plans), see peak
attenuation below
Pond 1 = 190,790 cf (190,536 cf design)
Pond 2 = 39,103 cf
Pond 3 = 48,719 cf
Peak Attenuation:
Drainage Area
2-Year Storm
10-Year Storm
South (Pre -Development)
5.39 cfs
7.56 cfs
North (Pre -Development)
3.41 cfs
4.78 cfs
South As -Built)
2.63 cfs
3.38 cfs
North As -Built
1.05 cfs
1.30 cfs
Permanent Pool As Built Conditions:
BMP Name
Average
Depth
SA/DA% (Per 90%TSS
with Avg. Depth)
SA Required
SA Provided
Pond 1
7.67ft 7.5ft
2.8
13,422 sf
49,685 sf
Pond 2
3.Oft
9.10
11,666 sf
14,123 sf
Pond 3
9.14ft 7.5ft
2.68
4,288 sf
14
EaVEDMARO��

Secondary BMP/SCM Analysis:
The level spreader and vegetated filter strip, as well. as the infiltration trenches downstream of Ponds 2
and 3, are constructed of approximately the same dimensions and intent as the designed facilities. The
infiltration areas shown on the survey were approximated based on the original stakeout locations of the
trenches from the design plans. Due to field conditions and proximity; to wetlands, the vegetated filter
strip's shape was altered to provide approximately the same filtering area.
Based on our review of the signed and sealed survey provided to Bohler by John L Pierce and Associates
Land Surveying, the constructed stormwater control measures meet the NCDEQ requirements from the
time of permitting and approval.
All supporting calculations have been provided in the appendix section of this memorandum.
Sincerely,
Bohler Engineering
Michael Theberge, P.E.

General Project Description/Stormwater Management
GENERAL PROJECT DESCRIPTION
Wal-Mart Real Estate Business Trust proposes to redevelop the existing land located along the south side
of West Corbett Avenue (NC Highway 24) and the west side of Hammock Beach Road in Swansboro,
North Carolina. This site currently consists of vacant land, an existing Walmart building with associated
parking, (3) existing ponds, and an existing stream. The proposed project area is approximately 1.84
acres and will include a redeveloped driveway extension to serve the existing Walmart Supercenter
building, fuel station, one outparcel, and f 623 parking spaces. The development will also include the
construction of landscaping, lighting, stormwater management facilities, the installation of all utilities to
support the development, and an access driveway to NC Highway 24. Pertinent data characterizing the
existing and proposed site conditions are shown on the accompanying Site Plan Documents.
STORMWATER MANAGEMENT
The pre -development condition of the site consists of two primary drainage areas. The southern portion
of the site drains to an existing pond and drainage feature at the south of the site. The northern portion
of the site drains to the existing stormwater network in Corbett Avenue and to the drainage feature to
the west of the property that ultimately drains to the existing stormwater network in Corbett Avenue.
Hydrographs have been generated for the 2, 10, and 100-year storm events for the pre- and post -
development conditions.
The post -development conditions maintain the same relative Drainage Treatment Areas, however to
provide water quality measures and rate control, three wet ponds were previously designed to intercept
flow from the impervious surfaces created by the development. Wet pond 1 discharges to the existing
drainage feature at the south of the property, and wet ponds 2 and 3 discharge to the existing network in
W. Corbett Ave. Due to the proximity of potential Shellfish Area (SA) waters, after discharging from the
pond, the water flows through underground infiltration trenches in order to infiltrate the required storm
volume for Wet Ponds 2 and 3. Wet Pond 1 discharges into a level spreader and vegetated filter strip in
order to provide "effective infiltration."
The wet ponds have been designed in accordance with the NCDENR Stormwater BMP Manual to provide
90% TSS removal for the water quality volume (WQV). The water quality volume for this project is
required to be the greater of 1.5" or the difference in the runoff from the pre- and post -development
conditions for the 1-yr, 24-hr storm depth. The wet ponds will also serve as a means of stormwater rate
control, and have been designed to reduce the post -development release rates for the 2 and 10-year
storm events to be at or below the corresponding pre -development rates. Infiltration of the WQV after
discharge from the wet ponds is provided through underground infiltration trenches.
The Dekalb Rational Method was utilized for calculating the peak runoff rates and generating
hydrographs for the pre- and post -development conditions as defined in the computer watershed
software "Hydraflow Hydrographs Extension for AutoCAD Civil 3D 2016". The hydrographs were
generated based on the precipitation amounts dictated by the NOAA Atlas 14 for the project site in
Swansboro, NC for each storm event.
The storm drainage system has been designed to intercept runoff at topographic low points and areas of
significant runoff quantities and convey stormwater to the stormwater management basins. The
Hyrdaflow StormSewers Extension was utilized for designing the storm conveyance system. Conveyance
design precipitation amounts are based on the 10-year storm event. Spread calculations are provided for

the inlets based on the 4"/hr rainfall intensity. Some spreads in the parking lot are excessively high,
because the proposed trench drain is not modeled in these calculations.
Per "Revised Final Geoiechnical Exploration Report" by S&ME, Inc., the subject site lies in an area
consisting mostly of Onslow series soils. The survey indicated that the Onslow series consists of
moderately well -drained soils that transition from a loamy fine sand to sandy and clayey loam with depth.
The subsoil is formed from loamy and sandy marine deposits.
Stormwater Management Analysis
The tables below show the calculations of the Water Quality Volume (WQV) for the three ponds that must
be discharged within 2-5 days and then effectively infiltrated as secondary treatment.
Wet Pond 1 WQV:
The proposed road work on Corbett Ave and previously constructed road work on Hammock Beach Rd
result in an increase in impervious area of approximately 43,020 sf, which also includes the impervious
area of the pump house and water tank, which do not flow to the wet ponds. Additional water quality
treatment storage volume is provided in Wet Pond 1 to account for this additional increase in impervious
area. For calculation purposes, the drainage area and impervious area draining to Wet Pond 1 have been
increased by the 43,020 sf value to account for the additional treatment being provided by the pond.
Total Treatment by Wet Pond 1 (includes offsite area):
Design Runoff (Pre) 0.183; in
Design Runoff (Post) 2.863t in
Drainage Area =
11.23
Acres
:Design Runoff (Pre)
7,437
13
Design Runoff (Post) _
116,653
ft3
Volume required =
109,216
ft3
A level spreader with vegetated filter strip is used for "effective infiltration" after Wet Pond 1. Due to the
storage volume of Wet Pond 1, the resulting outflow for the 10-year storm is very small and results in the
required length of the level spreader being relatively small. In our engineering judgment, the length of
the level spreader has been increased to provide a more conservative, constructible, and maintainable
system.
Wet Pond 2 WQV: Wet Pond 2 Infiltration Area Needed:
V +, 240751cf
K i 2.00.;in/hr
T ` 4.57 days
Design Runoff (Pre) = 4,751 ft3 A 1318 sf
Design Runoff (Post) = 28,832 ,ft3 W 24ft
Volume required = 24,076 'ft3 L 4.9 ft

Wet Pond 3 WQV:
Design Runoff, (Pre) =
Design Runoff (Post)
i
.. ........ ... ..i.. .. _
Drainage Area =
0.445; in
2.779' in
3.63 Acres
Design Runoff (Pre) =
5,706 ;ft3
Design Runoff (Post)
35,608 1ft3
Volume required =
29,902 tt3
Wet Pond 3 Infiltration Area Needed:
K
2.001inlhr
T
4.191days
A
1814'sf
w
24?ft
L
76fft

BMP Sizing:
For all 3 wet ponds, equation Option 2 from Figure 10-2b is used. The values used for each variable can
be found in the Wet Pond Supplement for each pond.
For Wet Pond 1, the two forebays have been designed to provide approximately 20% of the permanent
pool storage volume. The forebays are also sized proportionally to the drainage area flowing to each.
Forebay #1 receives flow from approximately 43% of the drainage area, while it is approximately 8.4%
of the permanent pool volume (or approximately 42% of the total forebay volume). Forebay #2 receives
flow from approximately 57% of the drainage area, while it is approximately 11.6% of the permanent
pool volume (or approximately 58% of the total forebay volume).
For all 3 wet ponds, a water quality orifice is used at the base of the riser structure to draw down the
water quality volume within 2-5 days. The next available outlet on the riser structure is placed above the
required water quality volume. The elevation of this next available outlet is considered the temporary
pool volume, and this elevation (and resulting pressure head value used for the orifice equation) was
used when determining the drawdown times through the water quality orifices.
The infiltration trenches proposed after Wet Ponds 2 and 3 were sized based on the drawdown times of
the water quality volume through the water quality orifice in the riser structures, as discussed above. The
infiltration trenches were sized based on the water quality volume, infiltration rate (based on soil borings
and infiltration estimates from a geotechnical engineer), and drawdown time of the upstream wet pond.
List of Important Modifications since Previous Approval:
Post -development drainage areas have changed due to proposed driveway extension
construction.
New E&SC plans are to be implemented, based on the new construction. Calculations and
narrative have been revised since the previous submission.
o Drainage areas in erosion and sediment control plans have been updated to match
stormwater drainage areas due to the additional impervious areas and diversion ditches
during erosion control that will direct water towards the storm inlet basins.
o New additional limits of disturbance are proposed with the modifications. Due to the
amount of BUA added to the previously approved SWM plans, we are proposing a Major
Modification to the existing approved permit.

BMP Design/Calculations
E--- �. ' --' 7

WET POND #1 WALMART SUPERCENTER BMP DESIGN CALCULATIONS
1I ; WATER QUALITY TO MEET 90% TSS REMOVAL
DRAINAGE AREA TO FACILITY = 11 23 Ar..
(Includes 43,020 sf of impervious area not draining to pond)
LAND USE = Walmart Supercenter
ESTIMATED PERCENT IMPERVIOUS = 82%
AVERAGE POOL DEPTH =
768
PERCENT IMPERVIOUS =
82%
SA/DA = 2.80 %
0.0280
SA REQUIRED =
11.2264 Ac. X
=
0.3143 Ac.
=
13,693 SF
)-E NA
Pre % Impervious =
0%
Post % Impervious =
82%
Rv(pre)=
0.05 infin
Rv(post)=
0.784 in/in
Design Rainfall =
3.65 in (1 yr, 24 hr)
Design Runoff (Pre) =
0.183 in
Design Runoff (Post) =
2.863 in
Drainage Area =
1123 Acres
Design Runoff (Pre) =
7,437 ft3
Design Runoff (Post) =
116,653 ft3
Volume required =
109,216 ft3
Total (including off -site)=
Pond Height above Orifice =
Orifice Invert Elevation =
FEET
0.0280
109,216 ft3
(Assumed to be 7.5' for SA/DA)
31.01 feet (109,755CF @ 31.01')
29.08 feet
Orifice Diameter (D) = 5.00
inches = 0.42
Orifice Area (a) = 0.1364
square feet
Gravitational Constant (g) = 32.2
ft/secz
Head (H) = 1.72
feet
Driving Head (Ho) = 0.574
feet
Discharge Coefficient (Co) = 0.6
Drawdown rate (Q) = 0.497
cfs
Time (t) = 219,588
seconds = 264
Note:
The above calculation is based
on the orifice equation where:
feet
days
7/24/20191:01 PM Page 1 of 1

PERM. POOL ELEV.
TEMP. POOL ELEV.
VEG. SHELF (BOT.)
'ERM. POOL ELEV.
VEG. SHELF (TOP)
VF%G. SHFI F (RnT )
PERM. POOL ELEV
VEG. SHELF (TOP)
Wet Pond 1 Design
Wet Pond 1 Treatment Volume - Main Pool
Elev
Area (so
Inc Storage (co Total Storage (co
29.08
49,6 7
49,685
0
0
30.00
57, ' 7
57,680
49, 18 49,388
49, 8
31.01
61, 59
61,859
60 352 60.367
109 70
32.00
65 71
65,992
6 ,161 63-286
17 ,831
32.25
7 ,008
76,000
1 ,705 17,749
19 ,536
Wet Pond 1 Permanent Pool Volume - Main Pool
Elev
Area (so
Inc Storage (co
Total Storage (co
12.00
3,303
0
0
13.00
8,360
0
0
14.00
11,288
0
0
15.00
12,757
0
0
16.00
13,982
0
0
17.00
15,202
0
0
18.00
16,425
0
0
19.00
17,737
17,081
17,081
20.00
19,075
18,406
35,487
21.00
20,476
19,776
55,263
22.00
21,949
21,213
76,475
23.00
23,477
22,713
99,188
24.00
25,010
24,244
123,432
25.00
26,647
25,829
149,260
26.00
28,313
27,480
176,740
27.00
30,001
29,157
205,897
28.00
31,939
30,970
236,867
28.58
33,334
18,929
255,796
29.08
36,620
17,489
273,285
29.58
39,688
19,077
292,362
Wet Pond 1 - Forebay#1
Elev
Area (so Inc Storage (co Total Storage (co
19.00
243 0
0
20.00
566 0
0
21.00
904 735
735
22.00
1,281 1,093
1,828
23.00
1,709 1,495
3,323
24.00
2,185 1,947
5,270
25.00
2,730 2,458
7,727
26.00
3,353 3,042
10,769
27.00
4,010 3,682
14,450
28.00
4,725 4,368
18,818
28.58
J,L I L 2,882
21,699
29.08
5,565 2,694
24,393
29.58
6,052 2,904
27,298
MAIN POOL & FOREBAY #1 UNALTERED
WITH THIS PERMIT MODIFICATION
49,388
109,755
173,041
190.790
SURVEYED TOP Of
SED. STORAGE (B(
POND) = 13.00'
OBSERVED TOP SE
STORAGE(BOT.
POND) = 18.00'
OBSERVED/SURVE 1
TOP SED.
STORAGE(BOT. POP
= 20.00'

VEG. SHELF (BOT.)
PERM. POOL ELEV.
VEG. SHELF (TOP)
Wet Pond 1 - Forebay#2
Elev
Area (sf)
Inc Storage (cf)
Total Storage (cf)
19.00
471
229
0
0
20.00
1,11
677
0
0
21.00
1,7
1163
1,4 8
920
1,4 8
920
22.00
2,3 2
1872
2, 3
1518
3, 81
2438
23.00
2,8 7
2591
2, 10
2232
6, 90
4669
24.00
3,5 1
3326
3, 99
2959
9, 89
7628
25.00
4,1 1
4087
3, 1
3707
1 130
11334
26.00
5, 40
4871
4 61
4479
1 ,791
15813
27.00
5, 16
5698
5 328
5285
2 ,119
21098
28.00
6, 19
6533
,917
6116
2 ,036
27213
28.58
6 74
6962
,797
3914
,833
31127
29.08
7 452
7500
,556
3616
6,389
34742
29.58
,683
7787
,784
3822
0,173
38564
DEPTH : 28.58 - 18.00 = 10.58
A(bot. shelf) = 45,508
A(bot. pond) = 16,425
A(perm. pool) = 49,685
Davg = 7.68
OBSERVED/SURVE`
TOP SED.
STORAGE(BOT. POI
= 20.00'

Permit No.
(to be provided by D WQ)
J&'Q-
�pF W ATFRQ
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form must be filled out printed and submitted.
The Required Items Checklist (Part Ill) must be printed, filled out and submitted along with all of the required information.
Project name
7179-000 Walmart Supercenter Swansboro, NC
Contact person
Michael A Theberge
Phone number
980-272-3400
Date
27-Feb-20
Drainage area number
Wet Pond 1
Site Characteristics
Drainage area
489,020 fe
Impervious area, post -development
398,718 fe
% impervious
81.53 %
Design rainfall depth
3.7 in
Storage Volume: Non -SA Waters
Minimum volume required
ft3
Volume provided ft3
Storage Volume: SA Waters
1.5" runoff volume 47,912 ft3
Pre -development 1-yr, 24-hr runoff 7,437 ft3
Post -development 1-yr, 24-hr runoff 116,653 ft3
Minimum volume required 109,216 ft3
Volume provided 109,755 ft3
Peak Flow Calculations
Is the pre/post control of the 1 yr 24hr storm peak flow required?
Y (Y or N)
1-yr, 24-hr rainfall depth
3.7 in
Rational C, pre -development
0.15 (unitless)
Rational C, post -development
0.80 (unitless)
Rainfall intensity: 1 -yr, 24-hr storm
0.15 Whir OK
Pre -development 1-yr, 24-hr peak flow
1.45 ft3/sec
Post -development 1-yr, 24-hr peak flow
25.00 ft3/sec
Pre/Post 1-yr, 24-hr peak flow control
23.55 ft3/sec
Elevations
Temporary pool elevation
31.01 fmsl
Permanent pool elevation
29.08 fmsl
SHWT elevation (approx. at the perm. pool elevation)
29.60 fmsl
Top of 10ft vegetated shelf elevation
29.58 fmsl
Bottom of 1 Oft vegetated shelf elevation
28.58 fmsl
Sediment cleanout, top elevation (bottom of pond)
18.00 fmsl
Sediment cleanout, bottom elevation
17.00 fmsl
Sediment storage provided
1.00 ft
Is there additional volume stored above the state -required temp. pool?
Y (Y or N)
Elevation of the top of the additional volume
31.0 fmsl OK
Form SW401-Wet Detention Basin-Rev.9-4/1all 2 Parts I. d II. Design Summary, Page 1 of 2

Permit
(to be provided by DWQ)
Surface Areas
Area, temporary pool 61,859 ft'
Area REQUIRED, permanent pool 13,693 ft
SAIDA ratio 2.80 (unitless)
Area PROVIDED, permanent pool, APerrn r1001 49,685 fe OK
Area, bottom of 1Oft vegetated shelf, AhO, Sh,,If 45,508 ft?
Area, sediment cieanout, top elevation (bottom of pond), Abatpwd 16,425 f?
Volumes
Volume, temporary pool
109,755 fe
OK
Volume, permanent pool, Vpenpod
332,420 fe
Volume, forebay (sum of forebays if more than one forebay)
59,135 f?
Forebay % of permanent pool volume
17.8% %
Insufficient forebay volume.
SAIDA Table Data
Design TSS removal
90 %
Coastal SAIDA Table Used?
Y (Y or N)
Mountain/Piedmont SAIDA Table Used?
N (Y or N)
SAIDA ratio
2.80 (unitless)
Average depth (used in SAIDA table):
Calculation option 1 used? (See Figure 10-2b)
N (Y or N)
Volume, permanent pool, Vperm-pod
332,420 ft3
Area provided, permanent pool, Ap.11n_pool
49,685 ft'
Average depth calculated
N/A ft
OK
Average depth used in SAIDA, da,,, (Round to nearest 0.5ft)
ft
Calculation option 2 used? (See Figure 10-2b)
Y (Y or N)
Area provided, permanent pool, A,.,n_,O ,
49,685 ft2
Area, bottom of 10ft vegetated shelf, AWLAW
45,508 ft'
Area, sediment cleanout, top elevation (bottom of pond), AboL-pwd
16,425 fe
"Depth" (distance b/w bottom of 10ft shelf and top of sediment)
10.58 ft
Average depth calculated
7.67 ft
OK
Average depth used in SAIDA, deV, (Round to down to nearest 0.5ft)
7.5 ft
OK
Drawdown Calculations
Drawdown through orifice?
Y (Y or N)
Diameter of orifice (if circular)
5.00 in
Area of orifice (if -non -circular)
in'
Coefficient of discharge (Co)
0.60 (unitless)
Driving head (H.)
0.57 ft
Drawdown through weir?
N (Y or N)
Weir type
N/A (unitless)
Coefficient of discharge (C,,,)
N/A (unitless)
Length of weir (L)
N/A ft
Driving head (H)
N/A ft
Pre -development 1-yr, 24-hr peak flow
1.45 fe/sec
Post -development 1-yr, 24-hr peak flow
25.00 8 /sec
Storage volume discharge rate (through discharge orifice or weir)
0.49 Osec
Storage volume drawdown time
2.54 days
OK, draws down in 2-5 days.
Additional Information
Vegetated side slopes
3 :1
OK
Vegetated shelf slope
10 :1
OK
Vegetated shelf width
10.0 ft
OK
Length of flowpath to width ratio
3.2 :1
OK
Length to width ratio
3.2 :1
OK
Trash rack for overflow & orifice?
Y (Y or N)
OK
Freeboard provided
1.0 ft
OK
Vegetated filter provided?
N (Y or N)
OK
Recorded drainage easement provided?
Y (Y or N)
OK
Capures all runoff at ultimate build -out?
Y (Y or N)
OK
Drain mechanism for maintenance or emergencies is:
PUMP
Form SW401-Wet Detention Basin-Rev.9-4/18/12 Parts I. E 11. Design Summary, Page 2 of 2

of w�re9
V-2-> �f
NCDENR s
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER - VEGETATED FILTER STRIP (LS-VFS) SUPPLEMENT
This form must be completely filled out, printed, initialed and submitted.
Project name 7179-000 Walmart Supercenter Swansboro, NC
Contact name Michael A Theberge
Phone number 980-272-3400
Date May 18, 2016
Drainage area number From Wet Pond 1
The purpose of the LS-VFS Other. Explained below
Stormwater enters LS-VFS from A BMP
Type of VFS Engineered filter strip (graded & sodded, slope < 8%)
Explanation of any "Other" responses above
If Stormwater Enters the LS-VFS from the Drainage Area
Drainage area
Impervious surface area
Percent impervious
Rational C coefficient
Peak flow from the 1 in/hr storm
Time of concentration
Rainfall intensity, 10-yr storm
Peak flow from the 10-yr storm
Design storm
Maximum amount of flow directed to the LS-VFS
Is a flow bypass system going to be used?
Explanation of any "Other" responses above
If Stormwater Enters the LS-VFS from a BMP
Type of BMP
Peak discharge from the BMP during the design storm
Peak discharge from the BMP during the 10-year storm
Maximum capacity of a 100-foot long LS-VFS
Peak flow directed to the LS-VFS
Is a flow bypass system going to be used?
Explanation of any "Other" responses above
Purpose: "Effective infiltration" after 90% TSS wet pond due to proximity to SA Waters
ft, Do not complete this section of the form.
fe Do not complete this section of the form.
°% Do not complete this section of the form.
Do not complete this section of the form.
cfs
Do not complete this section of the form
min
Do not complete this section of the form
inlhr
Do not complete this section of the form
cfs
Do not complete this sectiun of the form
Other. Explained below
cfs Do not complete this section of the ;urm.
(Y or N) Do not complete this section of the form.
3.65" (1-yr, 24-hr storm) due to proximity to SA Waters
Wet detention pond
0.51
cfs
0.7
cfs
10
cfs
0.7
cfs
N
(YorN)
Form SW401 LS-VFS - 29Jure2012 Rev.10 page 1 of 3

LS-VFS Design
Forebay surface area
Depth of forebay at stormwater entry point
Depth of forebay at stormwater exit point
Feet of level lip needed per cis
Computed minimum length of the level lip needed
Length of level lip provided
Width of VFS
Elevation at downslope base of level lip
Elevation at the end of the VFS that is farthest from the LS
Slope (from level lip to the end of the VFS)
Are any draws present in the VFS?
Is there a collector swale at the end of the VFS?
Bypass System Design (if applicable)
Is a bypass system provided?
Is there an engineered flow splitting device?
Dimensions of the channel (see diagram below):
M
B
W
y (flow depth for 10-year storm)
freeboard (during the 10-year storm)
Peak velocity in the channel during the 10-yr storm
Channel lining material
Does the bypass discharge through a wetland?
Does the channel enter the stream at an angle?
Explanation of any "Other" responses above
A BMP sq ft No fa6bay is it:iuirc.^
in
in
10
ftfcfs
7 ft Ten feet is the minimum level spreader length.
20
ft
50
ft
29.00
fmsl
28.00
fmsl
2.00
%
N
(Y or N) OK
N
(Y or N)
N (Y or N)
N (Y or N)
Pick one:
W
a s �
(Y or N)
(Y or N)
Form SW401 - LS-VFS - 29June2012 - Rev.10 page 2 of 3

EDIT Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result
in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to indicate the
following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been met,
attach justification.
Requried Item:
1. Plans (1" - 50' or larger) of the entire site showing:
- Design at ultimate build -out,
Off -site drainage (if applicable),
Delineated drainage basins (include Rational C coefficient per basin),
Forebay (if applicable),
High flow bypass system,
Maintenance access,
Proposed drainage easement and public right of way (ROW), and
Boundaries of drainage easement.
2. Plan details (1" = 30' or larger) for the level spreader showing:
- Forebay (if applicable),
High flow bypass system,
One foot topo lines between the level lip and top of stream bank,
Proposed drainage easement, and
Design at ultimate build -out.
Section view of the level spreader (1" = 20' or larger) showing:
Underdrain system (if applicable),
Level lip,
- Upslope channel, and
- Downslope filter fabric.
4. Plan details of the flow splitting device and supporting calculations (if applicable).
5. A construction sequence that shows how the level spreader will be protected from
sediment until the entire drainage area is stabilized.
If a non -engineered VFS is being used, then provide a photograph of the VFS showing
that no draws are present.
7. The supporting calculations.
8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
Initials Page or plan sheet number and any notes:
MT i
MT
MT
MT
MT
Forth SW401 - LS-VFS - 29June2012 - Rev.10 page 3 of 3

WET POND #2 WALMART SUPERCENTER BMP DESIGN CALCULATIONS
WATER QUALITY TO MEET 90% TSS REMOVAL
DRAINAGE AREA TO FACILITY = 2 94 Ac.
LAND USE = Walmart Supercenter
ESTIMATED PERCENT IMPERVIOUS = 77%
UPfit:, I1 c
AVERAGE POOL DEPTH = 3 FEET
PERCENT IMPERVIOUS = 77%
SA/DA = 910 % = 0.0910
SA REQUIRED = 2.94 Ac. X 0.0910
0.27 Ac.
11 666 SF
Pre % Impervious = 8%
Post % Impervious 77%
Rv = 0.05 + 0.9(I)
Rv(pre)= 0.122 in/in
Rv(pre)= 0.739 in/in
Design Rainfall = 365 in (1 yr, 24 hr)
Design Runoff (Pre) = 0.445 in
Design Runoff (Post) = 2.699 in
Drainage Area = 2.94 Acres
Design Runoff (Pre) = 4,757 fta
Design Runoff (Post) = 28,832 fta
Volume required = 24,075 fta
Other Impervious Area to be Treated =
0 sf
Other Runoff Depth to be Treated =
3.47 in
Other WQV to be Treated =
0 fta
Total (Including off -site)=
24,075 ft'
Pond Height above Orifice =
31.19 feet (29,445CF @ 31.19')
Orifice Invert Elevation =
29.36 feet
Orifice Diameter (D) =
1.75 inches = 0.15 feet
Orifice Area (A) =
0.0167 square feet
Gravitational Constant (g) =
32.2 ft/sec'
Head (H) =
1.76 feet
Driving Head (Ho) =
0.586 feet
Discharge Coefficient (Co) =
0.6
Drawdown rate (Q) =
0.062 cfs
Time (t) =
391,135 seconds = 4 53 days
Note:
The above calculation is based on the orifice equation where:
Q=CoA 29
7/30/2018 10:37 AM Page 1 of 1

PERM. POOL ELEV,
TEMP. POOL ELEV_
SURVEYED TOP
SED. STORAGE
(BOT. POND)= 20.00'
OBSERVED TOP
SED. STORAGE
(BOT. POND)= 25.00'
VEG SHELF (BOT.)
PERM. POOL ELE
VEG SHELF (TOP)
OBSERVEDiSURVEYED
TOP OF SED STORAGE
= 20.00'
Wet Pond 2 Design
Wet Pond 2 Treatment Volume - Total
Elev
Area (sf)
Inc Storage (cf)
Total Storage (cf)
29.36
14,123
0
0
30.00
16,714
9,868
9,868
31.00
19,105
17,910
27,777
31.19
19,621
3,679
29,445
31.75
20,826
11,325
39,103
Elev
19.00
Wet Pond 2 Permanent
Area (sf)
12
Pool Volume - Total
Inc Storage (cf)
0
Total Storage (cf)
0
20.00
335
0
0
21.00
793
0
0
22.00
1,338
0
0
23.00
2,154
0
0
24.00
3,160
0
0
25.00
4,261
0
0
26.00
5,445
4,853
4,853
27.00
6,876
6,161
11,014
28.00
8,226
7,551
18,565
28.86
10,388
8,004
26,569
V
29.36
11,831
5,555
32,123
29.86
13,008
6,210
38,333
VEG SHELF (BOT.)
PERM. POOL ELEV.
VEG SHELF (TOP)
Wet Pond 2 - Forebay
Elev
Area (sf)
Inc Storage (cf)
Total Storage (cf)
19.00
5
0
0
20.00
47
0
0
21.00
117
82
82
22.00
218
168
250
23.00
357
288
537
24.00
515
436
973
25.00
707
611
1,584
26.00
919
813
2,397
27.00
1,289
1,104
3,501
28.00
1,553
1,421
4,922
28.86
2,020
1,536
6,458
29.36
2,292
2,615
7,537
29.86
2,564
2,292
8,750
Depth: 28.86-25.00 = 3.86'
A(bot. shelf): 12,408sf
A(bot. pond): 4,261 sf
A(perm. pool): 14,123sf
D(avg.): 3.06'
D(used): 3.00'
Forebay Volume (perm. pool): 7,537cf
Total Volume (perm. pool): 32,123cf + 7.537cf = 39,660cf
% Forebay to Total Volume: 7,537cf i 39,660cf = 19.00°b

Permit
(to be provided by DWQ)
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information.
Project name 7179-000 Walmart Supercenter Swansboro, NC
Contact person Michael -A Theberge
Phone number 980-272-3400
Date
Drainage area number
r L
Site Characteristics
30-Jul-18
Wet Pond 2
Drainage area
128,200 fe
Impervious area, post -development
98,200 fe
% impervious
76.60 %
Design rainfall depth
3.7 in
Storage Volume: Non -SA Waters
Minimum volume required
ft3
Volume provided ft3
Storage Volume: SA Waters
1.5" runoff volume
11,849 ft3
Pre -development 1-yr, 24-hr runoff
4,757 ft3
Post -development 1-yr, 24-hr runoff
28,832 ft3
Minimum volume required
24,076 ft3
Volume provided
29,445 ft3
Peak Flow Calculations
Is the pretpost control of the 1 yr 24hr storm peak flow required?
Y (Y or N)
1-yr, 24-hr rainfall depth
3.7 in
Rational C, pre -development
0.21 (unitless)
Rational C, post -development
0.76 (unitiess)
Rainfall intensity: 1 -yr, 24-hr storm
0,15 in/hr OK
Pre -development 1-yr, 24-hr peak flow
0.40 ft3/sec
Post -development 1-yr, 24-hr peak flow
9.69 ft3lsec
Pre/Post 1-yr, 24-hr peak flow control
9.29 fOlsec
Elevations
Temporary pool elevation
31.19 fmal
Permanent pool elevation
29.36 fmsl
SHWT elevation (approx. at the perm. pool elevation)
29.00 fmsl
Top of 1 Oft vegetated shelf elevation
29.86 fmsl
Bottom of 1 Oft vegetated shelf elevation
28.86 fmsl
Sediment cleanout, top elevation (bottom of pond)
25.00 fmsl
Sediment cleanout, bottom elevation
24.00 fmsl
Sediment storage provided
1.00 ft
Is there additional volume stored above the state -required temp. pool?
N (Y or N)
Elevation of the top of the additional volume
fmsl
�pF W A �VVF
pY S['--ya �Y --
Form SW401-Wet Detention Basin-Rev.9-4/18/12 Parts I. & II. Design Summary, Page 1 of 2

Permit
(fo be provided by DWQ)
Surface Areas
Area, temporary pool
19,621 fe
Area REQUIRED, permanent pool
11,666 ft'
SAIDA ratio
9.10 (unitless)
Area PROVIDED, permanent pool, Aperm-ool
14,123 ft'
OK
Area, bottom of 1 Oft vegetated shelf, AWLshdf
12,408 ft'
Area, sediment cleanout, top elevation (bottom of pond), Abolmd
° 4,261 ftZ
Volumes
Volume, temporary pool
29,445 ft3
OK
Volume, permanent pool, VPerm-pool
39,660 ft3
Volume, forebay (sum of forebays if more than one forebay)
7,537 ft3
Forebay % of permanent pool volume
19.0% %
OK
SAIDA Table Data
Design TSS removal
90 %
Coastal SAIDA Table Used?
Y (Y or N)
Mountain/Piedmont SAIDA Table Used?
N (Y or N)
SAIDA ratio
9.10 (unitless)
Average depth (used in SAIDA table):
Calculation option 1 used? (See Figure 10-2b)
N (Y or N)
Volume, permanent pool, VPermyool
39,660 ft3
Area provided, permanent pool, • perm_Pnd
14,123 fe
Average depth calculated
NIA ft
OK
Average depth used in SAIDA, deV, (Round to nearest 0.5ft)
ft
Calculation option 2 used? (See Figure 10-2b)
Y (Y or N)
Area provided, permanent pool, Apemrt.Pool
14,123 fe
Area, bottom of 10ft vegetated shelf, Abol shelf
12,408 W
Area, sediment cleanout, top elevation (bottom of pond), Ahot_and
4,261 fe
"Depth" (distance b/w bottom of 1 Oft shelf and top of sediment)
3.86 ft
Average depth calculated
3.06 ft
OK
Average depth used in SAIDA, d,v, (Round to down to nearest 0.5ft)
3.0 ft
OK
Drawdown Calculations
Drawdown through orifice?
Y (Y or N)
Diameter of orifice (if circular)
1.75 in
Area of orifice (if -non -circular)
in'
Coefficient of discharge (Co)
0.60 (unitless)
Driving head (Ho)
0.59 ft
Drawdown through weir?
N (Y or N)
Weirtype
N/A (unitless)
Coefficient of discharge (C.)
N/A (unitless)
Length of weir (L)
N/A ft
Driving head (H)
N/A ft
Pre -development 1-yr, 24-hr peak Flow
0.40 ft3/sec
Post -development 1-yr, 24-hr peak flow
9.69 ft3/sec
Storage volume discharge rate (through discharge orifice or weir)
0.06 ft3/sec
Storage volume drawdown time
4.53 days
OK, draws down in 2-5 days.
Additional Information
Vegetated side slopes
3 :1
OK
Vegetated shelf slope
10.1
OK
Vegetated shelf width
10.0 ft
OK
Length of flowpath to width ratio
6 :1
OK
Length to width ratio
6 :1
OK
Trash rack for overflow & orifice?
Y (Y or N)
OK
Freeboard provided
1.0 ft
OK
Vegetated filter provided?
N (Y or N)
OK
Recorded drainage easement provided?
Y (Y or N)
OK
Capures all runoff at ultimate build -out?
Y (Y or N)
OK
Drain mechanism for maintenance or emergencies is:
PUMP
Form SW401-Wat Detention Basin-Rev.9-4/18H2 Parts I. & II. Design Summary, Page 2 of 2

Permit No.
(to be provided by DWQ)
Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will
result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to
indicate the following design requirements have been met. If the appiicant has designated an agent, the agent may initial below. If a
requirement has not been met, attach justification.
Pagel Plan
Initials Sheet No.
MT C-6-C-8_ 1. Plans (1" 50' or larger) of the entire site showing:
- Design at ultimate build -out,
- Off -site drainage (if applicable),
- Delineated drainage basins (include Rational C coefficient per basin),
- Basin dimensions,
Pretreatment system,
High flow bypass system,
- Maintenance access,
Proposed drainage easement and public right of way (ROW),
Overflow device, and
Boundaries of drainage easement.
MT D-1 2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing:
- Outlet structure with trash rack or similar,
Maintenance access,
Permanent pool dimensions,
Forebay and main pond with hardened emergency spillway,
Basin cross-section,
- Vegetation specification for planting shelf, and
- Filter strip.
_MT
D-1
3. Section view of the wet detention basin (1" 20' or larger) showing:
- Side slopes, 3:1 or lower,
- Pretreatment and treatment areas, and
- Inlet and outlet structures.
_SW-2
4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified
on the plans prior to use as a wet detention basin.
MT
Appendix_
5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay,
to verify volume provided.
MT
SW-2
6. A construction sequence that shows how the wet detention basin will be protected from sediment until the
entire drainage area is stabilized.
MT
Appendix
7. The supporting calculations.
_MT
Appendix
8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
_MT Appendix_ 9. A copy of the deed restrictions (if required).
_MT Appendix_ 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County
soil maps are not an acceptable source of soils information.
Form SW401-Wet Detention Basin-Rev.9-4/18/12 Part III. Required Items Checklist, Page 18 of 18

Permit No.
(to be provided by DWQ)
A , STORMWATER MANAGEMENT PERMIT APPLICATION FORM
NCDENR of waw e�aR-
401 CERTIFICATION APPLICATION FORM
INFILTRATION TRENCH SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part /I/) must be printed, filled out and submitted along with all of the required information.
Project name
7179-000 Walmart Supercenter Swansbom, NC
Contact person
Michael A Theberge
Phone number
980-272-3400
Date
7/24/2019
Drainage area number
From Wet Pond 2
Site Characteristics
Drainage area
128,200.00 ftz
Impervious area
98,200.00 fe
Percent impervious
76.6% %
Design rainfall depth
3.65 in
Peak Flow Calculations
1-yr, 24-hr rainfall depth
3.65
in
1-yr, 24-hr intensity
0.15
in/hr
Pre -development 1-yr, 24-hr discharge
0.40
ft3lsec
Pust-development 1-yr, 24-1hr discharge
0.06
ft31sec
Pre/Post 1-yr, 24-hr peak flow control
-0.34
ft3lsec
Storage Volume: Non -SA Waters
Minimum volume required
ft3
Volume provided
ft3
Storage Volume: SA Waters
1.5" runoff volume
11849.00
ft3
Pre -development 1-yr, 24-hr runoff volume
4,757.00
ft3
Post -development 1-yr, 24-hr runoff volume
28,832.00
ft3
Minimum volume required
24075.00
ft3
Volume provided
29,445.00
ft3 OK
Soils Report Summary
Soil type
A
Infiltration rate
2.00
in/hr
SHWT elevation
29.00
fmsl
Trench Design Parameters
Drawdown time
4.53
days OK
Perforated pipe diameter
1200.
in
Perforated pipe length
55.00
ft
Number of laterals
0
Stone type (if used)
#57
Stone void ratio
40%
Stone is free of fines?
Y
(Y or N) OK
Form SW401-Infiltration Trench-Rev.4 Parts I. & II. Design Summary, Page 1 of 2

Permit No.
(to be provided by OWQ)
Trench Elevations
Bottom elevation
29.00
fmsl
Raise basin bottom, Must be at least 2-ft above SHWT
Storage/overflow elevation
30.50
fmsl
Top elevation
31.00
fmsl
Trench Dimensions
Length (long dimension)
55.00
ft
Width (short dimension)
24.00
ft
Height (depth)
2.00
ft
OK
Additional Information
Maximum volume to each inlet into the trench?
ac-in
Length of vegetative filter for overflow
N/A
ft
OK
Number of observation wells
1
Distance to structure
15.00
ft
OK
Distance from surface waters
1,000.00
ft
OK
Distance from water supply well(s)
N/A
ft
OK
Separation from impervious soil layer
N/A
ft
OK
Depth of naturally occuring soil above SHWT
0.00
ft
Minimum of atleast 1-ft of naturally occuling soil above shwt
Bottom covered with 4-in of clean sand?
N/A
(Y or N)
11K
Proposed drainage easement provided?
Y
(Y or N)
OK
Capures all runoff at ultimate build -out?
Y
or N)
OK
Bypass provided for larger storms?
Y
(Y or N)
Trench wrapped with geotextile fabric?
Y
(Y or N)
Pretreatment device provided
Y
Wet Pond
Form SW401-Infiltration Tronch-Rov.4 Parts I. & II. Design Summary, Page 2 of 2

WET POND 93 WALMART SUPERCENTER BMP DESIGN CALCULATIONS
I:. ,' WATER QUALITY TO MEET 90% TSS REMOVAL
DRAINAGE AREA TO FACILITY = 3.65 Ac.
LAND USE = Walmart Supercenier
ESTIMATED PERCENT IMPERVIOUS 78%
AVERAGE POOL DEPTH = 914 FEET (Assumed to be 7.5' for SAIDA)
PERCENT IMPERVIOUS = 78%
SA1DA = 280 % = 0.0280
SA REQUIRED = 3.65 Ac. X 0.0280
= 0.10 Ac.
4.447 SF
1W9#0 }NAB OUAL ` W'a
Pre % Impervious = 8°%
Post °% Impervious = 78°%
Rv = 0.05 + 0.9(I)
Rv(pre)= 0.122 in/in
Rv(pre)= 0.750 in/in
Design Rainfall = 365 in (1 yr, 24 hr)
Design Runoff (Pre) = 0.445 in
Design Runoff (Post) = 2.737 in
Drainage Area = 3.65 Acres
Design Runoff (Pre) = 5,893 ft3
Design Runoff (Post) = 36,216 ft3
Volume required = 30,325 ft3
Other Impervious Area to be Treated =
0 sf
Other Runoff Depth to be Treated = 3.47 in
Other WQV to be Treated =
0 It,
Total (including off -site)= 30,325 ft3
Pond Height above Orifice = 31.12
feet (32,486CF @ 31.12')
Orifice Invert Elevation = 29.16
feet
Orifice Diameter (D) = 2.00
inches = 0.17 feet
Orifice Area (a) = 0.0218
square feet
Gravitational Constant (g) = 32.2
fUsec2
Head (H) = 1.88
feet
Driving Head (Ho) = 0.626
feet
Discharge Coefficient (Ca) = 0.6
Drewdown rate (Q) = 0.083
cfs
Time (t) = 364,991
seconds 422 days
Note:
The above calculation Is based on the orifice equation where:
=C,A ZgH.
7/24/2019 1:33 PM Page 1 of 1

PERM. POOL ELEV
TEMP. POOL ELEV.
Wet Pond 3 Design
Wet Pond 3 Treatment Volume
Elev
Area (sf)
Inc Storage (cf)
Total Storage (cf)
29.16
14,318
0
0
30.00
16,780
13,061
13,061
31.00
17,790
17,285
30,346
31.12
17,882
2,140
32,486
31.50
18,175
6,851
39,337
32.00
19,352
9,382
48,719
Wet Pond 3 Permanent Pool Volume
SURVEYED TOP
Elev
Area (sf)
Inc Storage (cf)
Total Storage (cf)
SED. STORAGE
12.00
1713
0
0
13.00
2,556
0
0
(BOT. POND)= 13.00'
14.00
3,003
0
0
15.00
3,418
0
0
16.00
3,756
3,587
3,587
OBSERVED TOP
17.00
4,121
3,939
7,526
SED. STORAGE
18.00
4,527
4,324
11,850
19.00
4,932
4,730
16,579
(BOT. POND)= 1 1-
20.00
4,342
4,637
21,216
21.00
5,759
5,051
26,267
22.00
6,174
5,967
32,233
23.00
6,496
6,335
38,568
24.00
6,819
6,658
45,226
25.00
7,143
6,981
52,207
26.00
7,468
7,306
59,512
27.00
7,804
7,636
67,148
28.00
8,131
7,968
75,116
VEG SHELF (BOT.)
28.66
9,069
5,676
80,792
PERM. POOL ELEV.
29.16
9,974
4,761
85,552
VEG SHELF (TOP)
1 29.66
10,698
5,168
90,720
Wet Pond 3 - Forebay
OBSERVEDiSURVEYED
Elev
Area (sf)
Inc Storage (cf)
Total Storage (cf)
TOP OF SED STORAGE
17.00
5
0
0
= 18.00'
18.00
234
0
0
19.00
521
378
378
20.00
818
670
1,047
21.00
1,128
973
2,020
22.00
1,355
1,242
3,262
23.00
1,581
1,468
4,730
24.00
1,788
1,685
6,414
25.00
2,003
1,896
8,310
26.00
2,224
2,114
10,423
27.00
2,471
2,348
12,771
28.00
2,701
2,586
15,357
VEG SHELF (BOT.)
28.66
3,621
2,086
17,443
PERM. POOL ELEV.
2�.16
4,344
1,994
19,434
VEG SHELF (TOP)
29.66
4,705
2,262
21,696
Depth: 28.66-15.00 = 13.66'
A(bot. shelf): 12,690sf
A(bot. pond): 3,418sf
A(perm. pool): 14,318sf
D(avg.): 9.14'
D(used): 7.5'
Forebay Volume (perm. pool): 19,434cf
Total Volume (perm. pool): 85,552cf + 19,434cf = 104,986cf

Permit No.
(to be provided by DWG)
�A SOP WAT�cgO
WDENR y r
STORMWATER MANAGEMENT PERMIT APPLICATION FORM �'a►
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part 111) must be printed, filled out and submitted along with all of the required information.
77,
Project name 7179-000 Walmart Supercenter Swansboro, NC
Contact person Michael A Theberge
Phone number 980-272-3400
Date 24-Jul-19
Drainage area number Wet Pond 3
Site Characteristics
Drainage area
158,811 fe
Impervious area, post -development
123,480 fe
% impervious
77.75 %
Design rainfall depth
3.7 in
Storage Volume: Non -SA Waters
Minimum volume required ft3
Volume provided ft3
Storage Volume: SA Waters
1.5" runoff volume 14,884 ft3
Pre -development 1-yr, 24-hr runoff 5,893 ft3
Post -development 1-yr, 24-hr runoff 36,218 ft3
Minimum volume required 30,325 ft3
Volume provided 32,486 ft3
Peak Flow Calculations
Is the prelpost control of the 1yr 24hr storm peak Flow required?
Y (Y or N)
1-yr, 24-hr rainfall depth
3.7 in
Rational C, pre -development
0.21 (unitless)
Rational C, post -development
0.77 (unitless)
Rainfall intensity: 1 -yr, 24-hr storm
0.15 in/hr OK
Pre -development 1-yr, 24-hr peak flow
0.27 ft3/sec
Post -development 1-yr, 24-hr peak flow
9.56 ft3lsec
Pre/Post 1-yr, 24-hr peak flow control
9.29 ft3lsec
Elevations
Temporary pool elevation
31.12 fmsl
Permanent pool elevation
29-16 fmsl
SHWT elevation (approx. at the perm. pool elevation)
28.75 fmsl
Top of 1 Oft vegetated shelf elevation
29.66 fmsl
Bottom of 1 Oft vegetated shelf elevation
28.66 fmsl
Sediment cleanout, top elevation (bottom of pond)
15.00 fmsl
Sediment cleanout, bottom elevation
14.00 fmsl
Sediment storage provided
1.00 ft
Is there additional volume stored above the state -required temp. pool?
N (Y or N)
Elevation of the top of the additional volume
fmsl
Form SW401-Wet Detention Basin-Rev.9-4/18/12 Paris I. & il. Design Summary, Page 1 of 2

Permit No.
(to be provided by DWQ)
Surface Areas
Area, temporary pool
17,882 ft2
Area REQUIRED, permanent pool
4,256 ft2
SAIDA ratio
2.68 (unitless)
Area PROVIDED, permanent pool, Aperm-peoi
14,318 fl?
OK
Area, bottom of 1 Oft vegetated shelf, Abol Shea
12,690 fC
Area, sediment cleanout, top elevation (bottom of pond), Abx.p"nd
3,418 ft2
Volumes
Volume, temporary pool
32,486 fts
OK
Volume, permanent pool, Vpe._Pool
104,986 ft3
Volume, forebay (sum of forebaysIf more than one forebay)
19,434 ft3
Forebay % of permanent pool volume
18.5% %
OK
SAIDA Table Data
Design TSS removal
90 %
Coastal SAIDA Table Used?
Y (Y or N)
Mountain/Piedmont SAIDA Table Used?
N (Y or N)
SAIDA ratio
2.68 (unitless)
Average depth (used in SAIDA table):
Calculation option 1 used? (See Figure 10-2b)
N (Y or N)
Volume, permanent pool, Vperm_pool
104,986 ft3
Area provided, permanent pool, Apeni_poo1
14,318 ft2
Average depth calculated
NIA ft
OK
Average depth used in SAIDA, deY, (Round to nearest 0.5ft)
ft
Calculation option 2 used? (See Figure 10-2b)
Y (Y or N)
Area provided, permanent pool, Aperm_pool
14,318 ft2
Area, bottom of 10ft vegetated shelf, Ab,1 Sear
12,690 ft2
Area, sediment cleanout, tap elevation (bottom of pond), Abolywd
3,418 ft2
"Depth" (distance b/w bottom of 1 Oft shelf and top of sediment)
13.66 ft
Average depth calculated
9.14 ft
OK
Average depth used in SAIDA, deY, (Round to down to nearest 0.5ft)
7.5 ft
Insufficient. Check calculation.
Drawdown Calculations
Drawdown through orifice?
Y (Y or N)
Diameter of orifice (if circular)
2.00 in
Area of orifice (if -non -circular)
in
Coefficient of discharge (Co)
0.60 (unitless)
Driving head (Ho)
0.63 ft
Drawdown through weir?
N (Y or N)
Weir type
NIA (unitless)
Coefficient of discharge (C.)
NIA (unitless)
Length of weir (L)
NIA ft
Driving head (H)
N/A ft
Pre -development 1-yr, 24-hr peak flow
0 27 ft3/sec
Post -development 1-yr, 24-hr peak flow
9.56 ft3/sec
Storage volume discharge rate (through discharge orifice or weir)
0.08 ft3/sec
Storage volume drawdown time
4.22 days
OK, draws down in 2-5 days.
Additional Information
Vegetated side slopes
3 :1
OK
Vegetated shelf slope
10 :1
OK
Vegetated shelf width
10.0 ft
OK
Length of flowpath to width ratio
3 :1
OK
Length to width ratio
2 :1
OK
Trash rack for overflow & orifice?
Y (Y or N)
OK
Freeboard provided
1.0 ft
OK
Vegetated filter provided?
N (Y or N)
OK
Recorded drainage easement provided?
Y (Y or N)
OK
Capures all runoff at ultimate build -out?
Y (Y or N)
OK
Drain mechanism for maintenance or emergencies is:
PUMP
Form SW401-Wet Detention Basin-Rev.9-4119/12 Parts I. & II. Design Summary, Page 2 of 2

Permit
(to be provided by DWQ)
NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM bl)W_ Rw Nme
401 CERTIFICATION APPLICATION FORM
INFILTRATION TRENCH SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information.
Project name
7179-000 Walmart Supercenter Swansboro, NC
Contact person
Michael A Theberge
Phone number
980-272-3400
Date
7/24/2019
Drainage area number
From Wet Pond 3
Site Characteristics
Drainage area
158,811.00 ftZ
Impervious area
123,480.00 ft
Percent impervious
77.8% %
Design rainfall depth
3.65 in
Peak Flow Calculations
1-yr, 24-hr rainfall depth
3.65 —in
1-yr, 24-hr intensity
0.15� in/hr
Pre -development 1-yr, 24-hr discharge
0.27 ft3/sec
Post -development 1-yr, 24-hr discharge
0.08 ft3/sec
Pre/Post 1-yr, 24-hr peak flow control
-0.19 ft3/sec
Storage Volume: Non -SA Waters
Minimum volume required
ft3
Volume provided
ft3
Storage Volume: SA Waters
1.5" runoff volume
14884.00 ft3
Pre -development 1-yr, 24-hr runoff volume
5,893 ft3
Post -development 1-yr, 24-hr runoff volume
36,218 ft3
Minimum volume required
30325.00 ft3
Volume provided
32,486.00 ft3 OK
Soils Report Summary
Soil type
A
Infiltration rate
2.00
inlhr
SHWT elevation
28.75
fmsl
Trench Design Parameters
Drawdown time
4.22
days OK
Perforated pipe diameter
12.00
in
Perforated pipe length
76.00
ft
Number of laterals
0
Stone type (if used)
#57
Stone void ratio
40%
Stone is free of fines?
Y
(Y or N) OK
Form SW401-Infiltration Trench-Rev.4 Parts I. & II. Design Summary, Page 1 of 2

Permit
(to be provided by DWQ)
Trench Elevations
Bottom elevation
Storage/overflow elevation
Top elevation
Trench Dimensions
Length (long dimension)
Width (short dimension)
Height (depth)
Additional Information
Maximum volume to each iniet into the trench?
Length of vegetative filter for overflow
Number of observation wells
Distance to structure
Distance from surface waters
Distance from water supply well(s)
Separation from impervious soil layer
Depth of naturally occuring soil above SHWT
Bottom covered with 4-in of clean sand?
Proposed drainage easement provided?
Capures all runoff at ultimate build -out?
Bypass provided for larger storms?
Trench wrapped with geotextile fabric?
Pretreatment device provided
28.75 fmsl Raise basin bottom, Must be at least 2-ft above SHWT
30.25 fmsl
30.50 fmsl
76.00 ft
24.00 ft
1.75 ft OK
ac-in
N/A
ft
OK
1
OK
25.00
ft
OK
1,000.00
ft
OK
N/A
ft
OK
N/A
ft
OK
000
ft
Minimum of atleast 1-ft of naturally occuring soil above shwt
N/A
(Y or N)
OK
Y
(Y or N)
OK
Y
(Y or N)
OK
Y
(Y or N)
OK
Y
(Y or N)
OK
Y
Wet Pond
Form SW401-Infiltration Trench-Rev.4 Parts I. & il. Design Surnmary, Page 2 of 2

Permit No.
(to be provided by OWQ)
Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will
result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to
indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a
requirement has not been met, attach justification.
Pagel Plan
Initials Sheet No.
_MT_ _C-6-C-8_ 1. Plans (l" 50' or larger) of the entire site showing:
Design at ultimate build -out,
- Off -site drainage (if applicable),
Delineated drainage basins (include Rational C coefficient per basin),
Trench dimensions,
Pretreatment system,
High flow bypass system,
Maintenance access,
- Proposed drainage easement and public right of way (ROW),
Overflow device, and
Boundaries of drainage easement.
__MT__ _ __D-1_ 2. Partial plan (1" = 30' or larger) and details for the infiltration trench showing:
Bypass structure,
Maintenance access,
Basin bottom dimensions,
Basin cross-section with benchmark for sediment cleanout,
Flow distribution detail for inflow,
Vegetated filter, and
Pretreatment device.
—MT—. 3. Section view of the infiltration trench (1" 20' or larger) showing:
Pretreatment and treatment areas, and
Inlet and outlet structures.
_MT_ 4. A table of elevations, areas, incremental volumes & accumulated volumes to verify the volume provided.
_MT__ _Appendix_ 5. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. The
results of the soils report must be verified in the field by DWQ, by completing & submitting the soils
investigation request form. County soil maps are not an acceptable source of soils information.
MT_ _SW-2, D-1_ 6. A construction sequence that shows how the infitiration basin will be protected from sediment until the
entire drainage area is stabilized.
_MT _Appendix_ 7. The supporting calculations.
_MT_ _Appendix_ 8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
_MT_ _Appendix_ 9. A copy of the deed restrictions (if required).
Form SW401--Infiltration Trench-Rev.4 Part III. Required Items Checklist, Page 3 of 3

Permit No.
(to be provided by DWQ)
Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will
result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to
indicate the following design requirements have been met. if the applicant has designated an agent, the agent may initial below.lf a
requirement has not been met, attach justification.
Page/ Plan
Initials Sheet No.
MT C-6-C-8_ 1. Plans (1" - 50' or larger) of the entire site showing:
- Design at ultimate build -out,
- Off -site drainage (if applicable),
- Delineated drainage basins (include Rational C coefficient per basin),
- Basin dimensions,
- Pretreatment system,
High flow bypass system,
Maintenance access,
Proposed drainage easement and public right of way (ROW),
- Overflow device, and
Boundaries of drainage easement.
2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing:
- Outlet structure with trash rack or similar,
- Maintenance access,
Permanent pool dimensions,
Forebay and main pond with hardened emergency spillway,
Basin cross-section,
Vegetation specification for planting shelf, and
Filter strip.
3. Section view of the wet detention basin (1" 20' or larger) showing:
- Side slopes, 3:1 or lower,
Pretreatment and treatment areas, and
Inlet and outlet structures.
_MT-SW-2 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified
on the plans prior to use as a wet detention basin.
MT Appendix_ 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay,
to verify volume provided.
_MT SW-2_ 6. A construction sequence that shows how the wet detention basin will be protected from sediment until the
entire drainage area is stabilized.
_MT Appendix_ 7. The supporting calculations.
MT Appendix_ 8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
_MT Appendix_ 9. A copy of the deed restrictions (if required).
_MT Appendix_ 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County
soil maps are not an acceptable source of soils information.
Form SW401-Wet Detention Basin-Rev.9-4/18/12 Part III. Required Items Checklist, Page 18 of 18

Hydraflow Table of Contents
190705 - Stormwater Ponds.gpw
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Friday, 07 / 5 / 2019
Watershed Model Schematic..................................................................................... 1
Hydrograph Return Period Recap............................................................................. 2
2 - Year
SummaryReport ......................................................................................................................... 3
HydrographReports................................................................................................................... 4
Hydrograph No. 1, Dekalb, Pre South...................................................................................... 4
Hydrograph No. 2, Dekalb, Pre North...................................................................................... 5
Hydrograph No. 3, Dekalb, Post to Pond 1.............................................................................. 6
Hydrograph No. 4, Dekalb, Post to Pond 2.............................................................................. 7
Hydrograph No. 5, Dekalb, Post to Pond 3.............................................................................. 8
Hydrograph No. 6, Dekalb, Pond Bypass South...................................................................... 9
Hydrograph No. 7, Dekalb, Pond Bypass North..................................................................... 10
Hydrograph No. 8, Reservoir, Out Pond 1............................................................................. 11
PondReport - Pond 1........................................................................................................ 12
Hydrograph No. 9, Reservoir, Out Pond 2............................................................................. 13
PondReport - Pond 2........................................................................................................ 14
Hydrograph No. 10, Reservoir, Out Pond 3........................................................................... 15
PondReport - Pond 3........................................................................................................ 16
Hydrograph No. 11, Combine, Post Combined South............................................................ 17
Hydrograph No. 12, Combine, Post Combined North............................................................ 18
10 Year
SummaryReport .......................................................................................................................
HydrographReports.................................................................................................................
19
20
Hydrograph No. 1, Dekalb, Pre South....................................................................................
20
Hydrograph No. 2, Dekalb, Pre North....................................................................................
21
Hydrograph No. 3, Dekalb, Post to Pond 1............................................................................
22
Hydrograph No. 4, Dekalb, Post to Pond 2............................................................................
23
Hydrograph No. 5, Dekalb, Post to Pond 3............................................................................
24
Hydrograph No. 6, Dekalb, Pond Bypass South....................................................................
25
Hydrograph No. 7, Dekalb, Pond Bypass North.....................................................................
26
Hydrograph No. 8, Reservoir, Out Pond 1.............................................................................
27
Hydrograph No. 9, Reservoir, Out Pond 2.............................................................................
28
Hydrograph No. 10, Reservoir, Out Pond 3...........................................................................
29
Hydrograph No. 11, Combine, Post Combined South............................................................
30
Hydrograph No. 12, Combine, Post Combined North............................................................
31
100 - Year
Surnmary Report..::............................................................ 32
HydrographReports................................................................................................................. 33
Hydrograph No. 1, Dekalb, Pre South.................................................................................... 33
Hydrograph No. 2, Dekalb, Pre North.................................................................................... 34
Hydrograph No. 3, Dekalb, Post to Pond 1............................................................................ 35
Hydrograph No. 4, Dekalb, Post to Pond 2............................................................................ 36
Hydrograph No. 5, Dekalb, Post to Pond 3............................................................................ 37
Hydrograph No. 6, Dekalb, Pond Bypass South.................................................................... 38

Contents continued...
190705 - Stormwater Ponds.gpw
Hydrograph No. 7, Dekalb, Pond Bypass North..................................................................... 39
Hydrograph No. 8, Reservoir, Out Pond 1............................................................................. 40
Hydrograph No. 9, Reservoir, Out Pond 2............................................................................. 41
Hydrograph No. 10, Reservoir, Out Pond 3........................................................................... 42
Hydrograph No. 11, Combine, Post Combined South............................................................ 43
Hydrograph No. 12, Combine, Post Combined North............................................................ 44
IDFReport .................................................................................................................. 45

I
Watershed Model Schematic Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Ob
0
Legend
IV
HXIL Origin
Description
1 Dekalb
Pre South
2 Dekalb
Pre North
3 Dekalb
Post to Pond 1
4 Dekalb
Post to Pond 2
11
5 Dekalb
Pust to Purrd 3
R npk.aib
Pond Bypass South
1
7 Dekalb
Pond Bypass North
8 Reservoir
Out Pond 1
9 Reservoir
Out Pond 2
10 Reservoir
Out Pond 3
11 Combine
Post Combined South
12 Combine
Post Combined North
Project: 190705 - Stormwater Ponds.gpw
Friday, 07 / 5 / 2019

Hydrograph Return Period RPFPRydrographsExtension for AutoCAD® Civil 3D®2018byAutodesk,Inc. v2018.3
Hyd.
Hydrograph
Inflow
Peak Outflow (cfs)
Hydrograph
No.
type
hyd(s)
Description
(origin)
1-yr
2-yr
3-yr
5-yr
10-yr
25-yr
50-yr
100-yr
1
Dekalb
------
-----
5.389
---- ---- 7.555
----
------
11.13
Pre South
2
Dekalb
-----
-----
3.411
---- --- 4.781
--
------
7.045
Pre North
i 3
Dekalb
-
-
55.74
----- - 72.38
---
-------
98.56
Post to Pond 1
4
Dekalb
------
-----
15.41
-- --- 20.01
-----
-------
27.25
Post to Pond 2
5
Dekalb
------
-----
19.39
--- --- 25.17
----
--- ---
34.28
Post to Pond 3
6
Dekalb
-----
-----
2.081
---- ---- 2.742
-----
-----
3,751
Pond Bypass South
7
Dekalb
-----
---- --
0.517
---- -- 0.672
-----
-----
0.915
Pond Rvnass North
8
Reservoir
3
---- --
0.529
----- ---- 0.613
-----
— ---
0.729
Out Pond 1
9
Reservoir
4
-------
0.349
---- ----- 0.398
---
--- -
0.465
Out Pond 2
10
Reservoir
5
-------
0.413
----- ------ 0.472
-----
0.551
Out Pond 3
11
Combine
6, 8,
-------
2.609
---- ------ 3.355
------
---- -
4.480
Post Combined South
12
Combine
' " '"
-----
1.058
----- ----- 1.306
-----
1.660
Post Combined North
Proj. file: 190705
- Stormwater
Ponds.gpw
Wednesday,
07 / 24 / 2019

2-YEAR 24-HOUR
STORM EVENT

Hydrograph Summary Repo rlydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd.
Hydrograph
Peak
Time
Time to
Hyd.
Inflow
Maximum
Total
Hydrograph
No.
type
flow
interval
Peak
volume
hyd(s)
elevation
strge used
Description
(origin)
(cfs)
(min)
(min)
(cult)
(ft)
(cuft)
1
Dekalb
1
225
30,411
1
—
Pre South
5.389
2
Dekalb
3.411
1
225
19,246
Pre North
55.74
3
Dekalb
1
25
50,002
- — -
Post to Pond 1
4
Dekalb
15.41
1
25
13,824
------
Post to Pond 2
5
Dekalb
19.39
1
25
17,389
----
Post to Pond 3
6
Dekalb
2.081
1
50
3,733
----
Pond Bypass South
7
Dekalb
0.517
1
25
464
---
Pond Bypass North
8
Reservoir
0.529
1
50
42,490
30.00
49,157
Out Pond 1
9
Reservoir
0.349
1
49
13,737
30.19
13,223
Out Pond 2
10
Reservoir
0.413
1
49
17,262
5
30.21
16,680
Out Pond 3
11
Combine
1
50
46,223
6, 8,
-----
Post Combined South
2.609
12
Combine
1.058
1
25
31,463
7, 9, 10,
--
Post Combined North
190705 - Stormwater Ponds.gpw
Return Period: 2 Year
Wednesday, 07 / 24 / 2019

Hydrograph Repold
Hydraflow Hydrographs Extension for AutoCAD® Civil 3138 2018 by Autodesk, Inc. v2018.3
Hyd. No. 1
Pre South
3
Wednesday, 07 / 24 / 2019
Hydrograph type
= Dekalb
Peak discharge
= 5.369 cfs
Storm frequency
= 2 yrs
Time to peak
= 225 min
Time interval
= 1 min
Hyd. volume
= 30,411 cuft
Drainage area
= 13.750 ac
Runoff coeff.
= 0.16*
Intensity
= 2.450 in/hr
Tc by User
= 45.00 min
OF Curve
= Swansboro1.IDF
Asc/Rec limb fact
= n/a
* Composite (Area/C) = [(13.550 x 0.15) + (0.200 x 0.95)] / 13.750
Q (cfs)
6.00
M
4.00
Ow
rM
1.00
0.00 --J.
0
Pre South
Hyd. No. 1 -- 2 Year
60 120 180 240 300
Hyd No. 1
Q (cfs)
6.00
5.00
4.00
3.00
2.00
1.00
' 0.00
360 420 480
Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 2
Pre North
4
Wednesday, 07 / 24 / 2019
Hydrograph type
= Dekalb
Peak discharge
= 3.411 cfs
Storm frequency
= 2 yrs
Time to peak
= 225 min
Time interval
= 1 min
Hyd. volume
= 19,246 cult
Drainage area
= 6.630 ac
Runoff coeff.
= 0.21*
Intensity
= 2.450 in/hr
Tc by User
= 45.00 min
OF Curve
= Swansborol.IDF
Asc/Rec limb fact
= n/a
* Composite (Area/C) = [(6.130 x 0.15) + (0.500 x 0.95)] / 6.630
Q (cfs)
4.00
r M
1.00
0.00 '
0 60
— Hyd No. 2
Pre North
Hyd. No. 2 -- 2 Year
120 180 240 300 360 420
Q (cfs)
4.00
3.00
2.00
1.00
—� 0.00
480
Time (min)

Hydrograph Report
5
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 3
Post to Pond 1
Hvdrograph type
= Dekalb
Peak discharge
Storm frequency
= 2 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Drainage area
= 10.230 ac
Runoff coeff.
Intensity
= 6.897 in/hr
Tc by User
OF Curve
= Swansborol.IDF
Asc/Rec limb fact
* Composite (Area/C) = [(2.070 x 0.15) + (8.160 x 0.95)] / 10.230
Q (cfs)
60.00
50.00
40.00
30.00
20.00
10.00
Post to Pond 1
Hyd. No. 3 -- 2 Year
Wednesday, 07 / 24 / 2019
= 55.74 r_.fs
= 25 min
= 50,002 cuft
= 0.79*
= 5.00 min
= n/a
Q (cfs)
60.00
50.00
30.00
20.00
10.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
— Hyd No. 3 Time (min)

Hydrograph Report 6
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3 Wednesday, 07 / 24 / 2019
Hyd. No. 4
Post to Pond 2
Hydrograph type
= Dekalb
Peak discharge
= 15.41 cfs
Storm frequency
= 2 yrs
Time to peak
= 25 min
Time interval
= 1 min
Hyd. volume
= 13,824 cuft
Drainage area
= 2.940 ac
Runoff coeff.
= 0.76*
Intensity
= 6.897 in/hr
Tc by User
= 5.00 min
OF Curve
= Swansboro1.IDF
Asc/Rec limb fact
= n/a
* Composite (Area/C) = [(2.250 x 0.95) + (0.690 x 0.15)] / 2.940
Q (cfs)
18.00
15.00
12.00
•M
. 11111111
Post to Pond 2
Hyd. No. 4 -- 2 Year
Q (cfs)
18.00
15.00
12.00
. 11,
3.00
0.00 Ir 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 N 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
Hyd No. 4 Time (min)

7
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3 Wednesday, 07 / 24 / 2019
Hyd. No. 5
Post to Pond 3
Hydrograph type
= Dekalb
Peak discharge
= 19.39 cfs
Storm frequency
= 2 yrs
Time to peak
= 25 min
Time interval
= 1 min
Hyd. volume
= 17,389 cult
Drainage area
= 3.650 ac
Runoff coeff.
= 0.77*
Intensity
= 6.897 in/hr
Tc by User
= 5.00 min
OF Curve
= Swansborol.IDF
Asc/Rec limb fact
= n/a
* Composite (Area/C) = [(2.830 x 0.95) + (0.820 x 0.15)] / 3.650
Q (cfs)
21.00
18.00
15.00
12.00
.M
3.00
Post to Pond 3
Hyd. No. 5 -- 2 Year
Q (cfs)
21.00
18.00
15.00
12.00
M
M
3.00
0.00 W I I I I I I I I I I I I I I I I 1 I I I I I 1 I N 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
-- - Hyd No. 5 Time (min)

8
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil MOD 2018 by Autodesk, Inc. v2018.3 Wednesday, 07 / 24 / 2019
Hyd. No. 6
Pond Bypass South
Hydrograph type
= IDekalb
Peak discharge
= 2.081 cfs
Storm frequency
= 2 yrs
Time to peak
= 50 min
Time interval
= 1 min
Hyd. volume
= 3,733 cult
Drainage area
= 2.500 ac
Runoff coeff.
= 0.15
Intensity
= 5.549 in/hr
Tc by User
= 10.00 min
OF Curve
= Swansboro1.IDF
Asc/Rec limb fact
= n/a
Q (cfs)
3.00
2.00
1.00
0.00 16, 1'
0 10 20
Hyd No. 6
Pond Bypass South
Hyd. No. 6 -- 2 Year
30 40 50 60 70 80
Q (cfs)
3.00
2.00
1.00
:211 0.00
90 100
Time (min)

Hydrograph Report
9
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 7
Pond Bypass North
Hydrograph type
= Dekalb
Peak discharge
Storm frequency
= 2 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Drainage area
= 0.500 ac
Runoff coeff.
Intensity
= 6.897 in/hr
Tc by User
OF Curve
= Swansboro1.IDF
Asc/Rec limb fact
Wednesday, 07 / 24 / 2019
= Q_517 r_.fs,
= 25 min
= 464 tuft
= 0.15
= 5.00 min
= n/a
Pond Bypass North
Q MS) Hyd. No. 7 -- 2 Year Q (Cfs)
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
000
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
000
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
— Hyd No. 7 Time (min)

Hydrograph Report
10
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 8
Out Pond 1
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 2 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Inflow hyd. No.
= 3 - Post to Pond 1
Max. Elevation
Reservoir name
= Pond 1
Max. Storage
Storage Indication method used.
50.00
40.00
30.00
20.00
10.00
0.00
0 300
— Hyd No. 8
M.
Out Pond 1
Hyd. No. 8 -- 2 Year
Wednesday, 07 / 24 / 2019
= 0.529 cfs
= 50 min
= 42,490 tuft
= 30.00 ft
= 49,157 tuft
Q (cf..
60.0C
50A
40.0C
30.0C
20.0C
10.0C
0.00
900 1200 1500 1800 2100 2400 2700 3000
Hyd No. 3 1.Total storage used = 49,157 cuff Time (min)

Pond Report 11
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3 Wednesday, 07 / 24 / 2019
Pond No.1 - Pond 1
Pond Data
Contours -User-defined contour areas. Conic method used for volume calculation. Begining Elevation 29.08 ft
Stage / Storage Table
:Stage (t)
Elevation (ft)
Contour area (sqft)
Incr. Stoi age (cuft)
Tutat storage (cuft)
0.00
29.08
49,637
0
0
0.92
30.00
57,687
49,318
49,318
1.93
31.01
61,859
60,352
109,670
2.92
32.00
65,771
63,161
172,831
3.17
32.25
76,008
17,705
190,536
Culvert / Orifice Structures
Weir Structures
[A]
[B] [C] [PrFRsr]
[A] [B]
[C]
[D]
Rise (in)
= 18.00
5.00 Inactive 0.00
Crest Len (ft)
= 24.00 20.65
Inactive
0.00
Span (in)
18.00
5.00 18.00 0.00
Crest El. (ft)
= 30.97 31.54
30.75
0.00
No. Barrels
1
1 1 0
Weir Coeff.
= 3.33 3.33
3.33
3.33
Invert El. (ft) = 29.03
29.08 30.00 0.00
Weir Type
= 1 Ciplti
Rect
---
Length (ft)
= 157.00
0.00 0.00 0.00
Multi -Stage
= Yes No
Yes
No
Slope (%)
= 0.68
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
Yes Yes 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 / Storage / Discharge
Table
Stage
Storage Elevation
Clv A Clv B
Clv C
PrfRsr Wr A
Wr B Wr C
Wr D
ExHi User
Total
ft
cuft ft
cfs cfs
cfs
cfs cfs
cfs cfs
cfs
cfs cfs
cfs
0.00
0 29.08
0.00 0.00
0.00
-- 0.00
0.00 0.00
--
0.000
0.92
49,318 30.00
0.55 is 0.53 is
0.00
-- 0.00
0.00 0.00
---
0.530
1.93
109,670 31.01
1.43 is 0.79 is
0.00
--- 0.64
0.00 0.00
---
--- --
1.429
2.92
172,831 32.00
10.84 oc 0.04 is
0.00
10.69
s 21.45 0.00
- ---
32.18
3.17
190,536 32.25
11.36 oc 0.03 is
0.00
11.20
s 41.14 0.00
--- ---
52.37

Hydrograph
Report
12
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk,
Inc. v2018.3
Wednesday, 07 / 24 ! 2019
Hyd. No. 9
Out Pond 2
-!ydrograph. type
=Reservoir
Peak discharge
= 0.349 cfs
Storm frequency
= 2 yrs
Time to peak
= 49 min
Time interval
= 1 min
Hyd, volume
= 13,737 cult
Inflow hyd. No.
= 4 - Post to Pond 2
Max. Elevation
= 30.19 ft
Reservoir name
= Pond 2
Max. Storage
= 13,223 cuft
Storage Indication method used.
Out Pond 2
Q (Cfs) Hyd. No. 9 -- 2 Year Q (cfs)
18.00 18.00
15.00 15.00
12.00 12.00
9.00 9.00
6.00 6.00
6
3.00 3.00
i
0.00 aim
0.00
0 240 480 720 960 1200 1440 1680 1920 2160 2400 2640
Time (min)
— Hyd No. 9 Hyd No. 4 _ Total storage used = 13,223 cuft

Pond Report
13
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Pond No. 2 - Pond 2
Pond Data
Contours -User-defined contour areas. Conic method used for volume calculation. Begining Elevation = 29.36 ft
Stage / Storage Table
Stage (ft)
Elevation (ft)
0.00
29.36
0.64
30.00
1.64
31.00
2.39
31.75
Contour area (sqft)
14,123
16,714
19,105
20,826
Incr. Storage (curt)
0
9,855
17,894
14,968
Total storage (cufY)
0
9,855
27,750
42,718
Wednesday, 07 / 24 / 2019
Culvert / Orifice Structures
Weir Structures
[A]
[B] [C]
[PrfRsr]
[A]
[B]
[C]
[D]
Rise (in) = 15.00
1.75 0.00
0.00
Crest Len ft
= 24.00
Inactive
0.00
0.00
Span (in) = 15.00
1.75 0.00
0.00
Crest El. (ft)
= 31.19
31.25
0.00
0.00
No. Barrels = 1
1 0
0
Weir Coeff.
= 3.33
3.33
3.33
3.33
Invert El. (ft) = 29.28
29.36 0.00
0.00
Weir Type
= 1
Ciplti
---
---
Length(ft) = 237.71
0.00 0.00
0.00
Multi -Stage
= Yes
No
No
No
Slope (%) = 0.60
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
Yes 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 0c) and submergence (s).
Stage / Storage / Discharge Table
Stage Storage Elevation
Clv A
Clv B Clv C
PrfRsr Wr A
Wr B
Wr C
Wr D
Exfil User
Total
ft cuft ft
cfs
cis cfs
cfs cfs
cfs
cfs
cfs
cfs cfs
cfs
0.00 0 29.36
0.00
0.00 ---
0.00
0.00
--
- ---
0.000
0.64 9,855 30.00
0.06 is
0.06 is
0.00
0.00
--
---
0.303
1.64 27,750 31.00
0.10 is
0.10 is
0.00
0.00
0.503
2.39 42,718 31.75
6.06 oc
0.01 is
6.06 s
0.00
--
29.35

Hydrograph
Report
14
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Wednesday, 07 / 24 / 2019
Hyd. No. 10
Out Pond 3
Hydrogranh type
= Reservoir
Peak discharge
= 0.413 cfs
Storm frequency
= 2 yrs
Time to peak
= 49 min
Time interval
= 1 min
Hyd. volume
= 17,262 cuft
Inflow hyd. No.
= 5 - Post to Pond 3
Max. Elevation
= 30.21 ft
Reservoir name
= Pond 3
Max. Storage
= 16,680 cuft
Storage Indication method used.
18.00
15.00
12.00
• II
WE
3.00
0.00
0 240 480
- Hyd No. 10
720
Out Pond 3
Hyd. No. 10 -- 2 Year
Q (cfs)
21.00
18.00
15.00
12.00
If 1
M E4
0.00
960 1200 1440 1680 1920 2160 2400 2640 2880
Time (min)
Hyd No. 5 Total storage used = 16,680 cuft

Pond Report 15
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3 Wednesday, 07 / 24 / 2019
Pond No. 3 - Pond 3
Pond Data
Contours -User-defined contour areas. Conic method used for volume calculation. Begining Elevation 29.16 ft
Stage / Storage Table
Stage (ft)
Elevation (a)
0.00
29.16
0.84
30.00
1.84
31.00
2.34
31.50
2.84
32.00
Contour area (sgft)
14,318
16,780
17,790
18,175
19,352
Incv. Storage (tuft)
0
13,046
17,281
8,990
9,379
Culvert / Orifice Structures Weir Structures
Total storage (cult)
0
13,046
30,327
39,317
48,696
[A]
[B] [C]
[PrfRsr]
[A]
[B]
[C]
[D]
Rise (in)
= 15.00
2.00 0.00
0.00
Crest Len (ft)
= 24.00
Inactive
Inactive
0.00
Span (in)
= 15.00
2.00 0.00
0.00
Crest El. (ft)
= 31.12
30.70
31.50
0.00
No. Barrels
= 1
1 0
0
Weir Coeff.
= 3.33
3.33
3.33
3.33
Invert El. (ft) = 29.05
29.16 0.00
0.00
Weir Type
= 1
Rect
Rect
---
Length (ft)
= 248.19
0.00 0.00
0.00
Multi -Stage
= Yes
Yes
No
No
Slope (%)
= 0.90
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
Yes 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 / Storage / Discharge
Table
Stage
Storage Elevation
Clv A
Clv B Clv C
PrfRsr Wr A
Wr B
Wr C
Wr D
Exfii User
Total
ft
cuft ft
cfs
cfs cfs
cfs cfs
cfs
cfs
efs
efs cfs
cfs
0.00
0 29.16
0.00
0.00
--- 0.00
0.00
0.00
--- --
0.000
0.84
13,046 30.00
0.09 is
0.09 is
-- 0.00
0.00
0.00
---
--- ---
0.365
1.84
30,327 31.00
0.14 is
0.14 is
0.00
0.00
0.00
--
-- ---
0.557
2.34
39,317 31.50
6.78 oc
0.01 is --
6.76 s
0.00
0.00
--
-- ---
27.10
2.84
48,696 32.00
7.27 oc
0.00 is -
7.26 s
0.00
0.00
--
-- -
28.34

Hydrograph Report
16
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 11
Post Combined South
Hydrograph type = Combine Peak discharge
Storm frequency = 2 yrs Time to peak
Time interval = 1 min Hyd. volume
Inflow hyds. = 6, 8 Contrib. drain. area
2.00
1.00
M
Post Combined South
Hyd. No. 11 -- 2 Year
300 600 900 1200 1500 1800
Hyd No. 11 Hyd No. 6 — Hyd No. 8
Wednesday, 07 / 24 / 2019
= 2.609 cfs
= 50 min
= 46,223 tuft
= 2.500 ac
2100 2400 2700
Q (cf.,
3.00
2.00
1.00
0.00
3000
Time (min)

Hydrograph
Report
17
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Wednesday, 07 / 24 / 2019
Hyd. No. 12
Post Combined North
Hydrograph type
= Combine
Peak discharge
= 1.056 cfs
Storm frequency
= 2 yrs
Time to peak
= 25 min
Time interval
= 1 min
Hyd. volume
= 31,463 cuft
Inflow hyds.
= 7, 9, 10
Contrib. drain. area
= 0.500 ac
1.00
240 480 720
Hyd No. 12
Post Combined North
Hyd. No. 12 -- 2 Year
960 1200 1440 1680
Hyd No. 7 - Hyd No. 9
1920 2160 2400
- Hyd No. 10
Q (cfs)
2.00
1.00
0.00
2640
Time (min)

10-YEAR 24-HOU R
STORM EVENT

18
Hydrograph Summary Repo rlydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd.
Hydrograph
Peak
Time
Time to
Hyd.
Inflow
Maximum
Total
Hydrograph
No.
type
flow
interval
Peak
volume
hyd(s)
elevation
strge used
Description
(origin)
(cfs)
(min)
(min)
(cult)
(ft)
(cuft)
1
Dekalb
1
225
42,634
-----
---
Pre South
7.555
2
Dekalb
4.781
1
225
26,982
----
----
Pre North
72.38
3
Dekalb
1
25
64,929
-----
----
Post to Pond 1
4
Dekalb
20.01
1
25
17,951
----
-----
Post to Pond 2
5
Dekalb
25.17
1
25
22,580
----
----
Post to Pond 3
6
Dekalb
2.742
1
50
4,919
--
—
Pond Bypass South
7
Dekalb
0.672
1
25
603
---
---
Pond Bypass North
8
Reservoir
0.613
1
50
55,701
3
30.24 63,915
Out Pond 1
9
Reservoir
0.398
1
49
17,837
4
30.41 17,248
Out Pond 2
10
Reservoir
0.472
1
49
22,411
5
30.50 21,75(
Out Pond 3
11
Combine
1
50
60,621
6, 8,
----
Post Combined South
3.355
12
Combine
1.306
1
25
40,850
7, 9, 10,
-----
Post Combined North
190705 - Stormwater Ponds.gpw
Return Period: 10 Year
Wednesday, 07 / 24 / 2019

19
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3 Wednesday, 07 / 24 / 2019
Hyd. No. 1
Pre South
Hydrograph type
= Dekalb
Peak discharge
= 7.555 cfs
Storm frequency
= 10 yrs
Time to peak
= 225 min
Time interval
= 1 min
Hyd. volume
= 42,634 cuft
Drainage area
= 13.750 ac
Runoff coeff.
= 0.16*
Intensity
= 3.434 in/hr
Tc by User
= 45.00 min
OF Curve
= Swansborol.IDF
Asc/Rec limb fact
= n/a
* Composite (Area/C) = [(13.550 x 0.15) + (0.200 x 0.95)] / 13.750
Q (cfs)
8.00
N. 101111
4.00
2.00
!WIT
Pre South
Hyd. No. 1 -- 10 Year
Q (cfs)
8.00
6.00
4.00
2.00
0 60 120 180 240 300 360 420 480
— Hyd No. 1 Time (min)

20
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3 Wednesday, 07 / 24 / 2019
Hyd. No. 2
Pre North
Hydrograph type
= Dekalb
Peak discharge
= 4.781 cfs
Storm frequency
= 10 yrs
Time to peak
= 225 min
Time interval
= 1 min
Hyd. volume
= 26,982 cult
Drainage area
= 6.630 ac
Runoff coeff.
= 0.21 *
Intensity
= 3.434 in/hr
Tc by User
= 45.00 min
OF Curve
= Swansborol .IDF
Asc/Rec limb fact
= n/a
* Composite (Area/C) = [(6.130 x 0.15) + (0.500 x 0.95)] / 6.630
Q (cfs)
5.00
4.00
3.00
2.00
1.00
M,
Pre North
Hyd. No. 2 -- 10 Year
Q (cfs)
5.00
4.00
3.00
2.00
1.00
IIIIIIIA911
0 60 120 180 240 300 360 420 480
Hyd No. 2 Time (min)

Hydrograph Report
21
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 3
Post to Pond 1
Hydrograph type
= Dekalb
Peak discharg
Storm frequency
= 10 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Drainage area
= 10.230 ac
Runoff coeff.
Intensity
= 8.957 in/hr
Tc by User
OF Curve
= Swansborol .IDF
Asc/Rec limb fact
* Composite (Area/C) = [(2.070 x 0.15) + (8.160 x 0.95)] / 10.230
Q (cfs)
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00
Post to Pond 1
Hyd. No. 3 -- 10 Year
Wednesday, 07 / 24 / 2019
= 72.38 Ofc
= 25 min
= 64,929 cuft
= 0.79*
= 5.00 min
= n/a
Q (cfs)
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.00 w I I I I I I I I I I I I I I I I I I 1 I I I I I � 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
-- Hyd No. 3 Time (min)

22
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3 Wednesday, 07 / 24 / 2019
Hyd. No. 4
Post to Pond 2
Hydrograph type
= Dekalb
Peak discharge
= 20.01 cfs
Storm frequency
= 10 yrs
Time to peak
= 25 min
Time interval
= 1 min
Hyd. volume
= 17,951 cuft
Drainage area
= 2.940 ac
Runoff coeff.
= 0.76*
Intensity
= 8.957 in/hr
Tc by User
= 5.00 min
OF Curve
= Swansborol.IDF
Asc/Rec limb fact
= n/a
" Composite (Area/C) = [(2.250 x 0.95) + (0.690 x 0.15)1 / 2.940
Q (cfs)
21.00
18.00
15.00
12.00
3.00
Post to Pond 2
Hyd. No. 4 -- 10 Year
Q (cfs)
21.00
18.00
15.00
12.00
• E1
3.00
0.00 --r I I I I 1 1 I 1 I 1 I I 1 I 1 I I I I I 1 1 I I �w 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
Hyd No. 4 Time (min)

23
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3 Wednesday, 07 / 24 / 2019
Hyd. No. 5
Post to Pond 3
Hydrograph type
= Dekalb
Peak discharge
= 25.17 cfs
Storm frequency
= 10 yrs
Time to peak
= 25 min
Time interval
= 1 min
Hyd. volume
= 22,580 tuft
Drainage area
= 3.650 ac
Runoff coeff.
= 0.77*
Intensity
= 8.957 in/hr
Tc by User
= 5.00 min
OF Curve
= Swansborol.IDF
Asc/Rec limb fact
= n/a
Composite (Area/C) = [(2.830 x 0.95) + (0.820 x 0.15)] / 3.650
Q (cfs)
28.00
24.00
20.00
12.00
4.00
Post to Pond 3
Hyd. No. 5 -- 10 Year
100
Q (cfs)
28.00
24.00
20.00
16.00
12.00
4.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
- Hyd No. 5 Time (min)

24
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil MOD 2018 by Autodesk, Inc. v2018.3 Wednesday, 07 / 24 / 2019
Hyd. No. 6
Pond Bypass South
Hydrograph type
= Dekalb
Peak discharge
= 2.742 cfs
Storm frequency
= 10 yrs
Time to peak
= 50 min
Time interval
= 1 min
Hyd. volume
= 4,919 cuft
Drainage area
= 2.500 ac
Runoff coeff.
= 0.15
Intensity
= 7.312 in/hr
Tc by User
= 10.00 min
OF Curve
= Swansboro1.IDF
Asc/Rec limb fact
= n/a
Q (cfs)
3.00
1.00
M
Pond Bypass South
Hyd. No. 6 -- 10 Year
i
10 20 30 40 50 60 70 80
Hyd No. 6
Q (cfs)
3.00
2.00
1.00
'� 0.00
90 100
Time (min)

Hydrograph Report
25
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 7
Pond Bypass North
H%Irirograph type
= Dekalb
Peak discharge
Storm frequency
= 10 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Drainage area
= 0.500 ac
Runoff coeff.
Intensity
= 8.957 in/hr
Tc by User
OF Curve
= Swansborol.IDF
Asc/Rec limb fact
Q (cfs)
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30
Pond Bypass North
Hyd. No. 7 -- 10 Year
Wednesday, 07 / 24 / 2019
= 0.672 cfr
= 25 min
= 603 cult
= 0.15
= 5.00 min
= n/a
Q (cfs)
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30

Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 8
Out Pond 1
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 10 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Inflow hyd. No.
= 3 - Post to Pond 1
Max. Elevation
Reservoir name
= Pond 1
Max. Storage
Storage Indication method used
Q (cfs)
80.00
70.00
- 1I
50.00
40.00
30.00
20.00
10.00
26
Wednesday, 07 / 24 / 2019
= 0.613 cfs
= 50 min
= 55,701 cuft
= 30.24 ft
= 63,915 tuft
Q (cfi
80.0C
70.0(
60A
50.0(
40.0(
30.0(
20.0C
10.0C
0.00 - --
0 300 600 900 1200 1500 1800 2100 2400 2700 3000
Time (min)
— Hyd No. 8 — Hyd No. 3 Total storage used = 63,915 cuft

Hydrograph Report
27
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 9
Out Pond 2
Hydrograph type
= ReseR/oir
Peak discharge
Storm frequency
= 10 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Inflow hyd. No.
= 4 - Post to Pond 2
Max. Elevation
Reservoir name
= Pond 2
Max. Storage
Storage Indication method used.
ti : 1 1
15.00
12.00
• OX
. OU
3.00
240 480
Hyd No. 9
Out Pond 2
Hyd. No. 9 -- 10 Year
Wednesday, 07 / 24 / 2019
= 0.398 cfs
= 49 min
= 17,837 cuft
= 30.41 ft
= 17,248 cult
Q (cfs)
21.00
18.00
15.00
12.00
'• X
M
3.00
0.00
720 960 1200 1440 1680 1920 2160 2400 2640 2880
Time (min)
Hyd No. 4 Total storage used = 17,248 cuft

Hydrograph Report
28
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 10
Out Pond 3
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 10 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Inflow hyd. No.
= 5 - Post to Pond 3
Max. Elevation
Reservoir name
= Pond 3
Max. Storage
Storage Indication method used
Q (cfs)
28.00
24.00
rM
16.00
12.00
M
4.00
M
300 600
Hyd No. 10
Out Pond 3
Hyd. No. 10 -- 10 Year
Wednesday, 07 124 / 2019
= 0.472 cfs
= 49 min
= 22,411 cuft
= 30.50 ft
= 21,750 cult
Q (cf..
28.00
24.0C
20.0C
16.0(
12.0(
4.00
0.00
900 1200 1500 1800 2100 2400 2700 3000
- Hyd No. 5 Total storage used = 21,750 cuft Time (min)

Hydrograph
Report
29
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Wednesday, 07 / 24 / 2019
Hyd. No. 11
Post Combined South
Hydrograph type
= Combine
Peak discharge
= 3.355 cfs
Storm frequency
= 10 yrs
Time to peak
= 50 min
Time interval
= 1 min
Hyd. volume
= 60,621 tuft
Inflow hyds.
= 6, 8
Contrib. drain. area
= 2.500 ac
Post Combined South
Q (cfs) Hyd. No. 11 -- 10 Year
4.00
RM
r M
1.00
1MTa
Q (cf.-
4.00
3.00
2.00
1.00
0 300 600 900 1200 1500 1800 2100 2400 2700 3000
Time (min)
Hyd No. 11 - Hyd No. 6 Hyd No. 8

Hydrograph Report
30
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 12
Post Combined North
Hydrograph type
= Combine
Peak discharge
Storm frequency
= 10 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Inflow hyds.
= 7, 9, 10
Contrib. drain. area
1.00
Wednesday, 07 / 24 12019
= 1.305 cfs
= 25 min
= 40,850 cult
= 0.500 ac
Post Combined North
Hyd. No. 12 -- 10 Year
240 480
720 960 1200
1440 1680
1920 2160 2400
Hyd No. 12
Hyd No. 7
- Hyd No. 9
Hyd No. 10
Q (cfs)
2.00
1.00
0.00
2640
Time (min)

31
Hydrograph Summary Repo rlydraflowHydrographsExtension for AutoCAD® Civil 3D®2018byAutodesk,Inc. v2018.3
Hyd.
Hydrograph
Peak
Time
Time to
Hyd.
Inflow
Maximum
Total
Hydrograph
No.
type
flow
interval
Peak
volume
hyd(s)
elevation
strge used
Description
(origin)
(cfs)
(min)
(min)
(cuft)
(ft)
(cuft)
1
Dekalb
11.13
1
225
62,820
---
------
Pre South
2
Dekalb
7.045
1
225
39,756
----
--
--
Pre North
3
Dekalb
98.56
1
25
88,408
-----
--
------
Post to Pond 1
4
Dekalb
27.25
1
25
24,443
----
---
---
Post to Pond 2
5
Dekalb
34.28
1
25
30,745
----
---
---
Post to Pond 3
6
Dekalb
3.751
1
50
6,730
----
----
— - -
Pond Bypass South
7
Dekalb
0.915
1
25
820
----
----
---
Pond Bypass North
8
Reservoir
0.729
1
50
75,587
3
30.63
87,164
Out Pond 1
9
Reservoir
0.465
1
49
24,277
4
30.77
23,603
Out Pond 2
10
Reservoir
0.551
1
49
30,494
5
30.97
29,751
Out Pond 3
-----
11
Combine
4.480
1
50
82,317
6, 8,
—
Post Combined South
12
Combine
1.660
i
1
25
55,592
7, 9, 10,
-----
----
Post Combined North
190705 - Stormwater Ponds.gpw
Return Period: 100 Year
Wednesday, 07 / 24 / 2019

Hydrograph Report
39
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 8
Out Pond 1
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 100 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Inflow hyd. No.
= 3 - Post to Pond 1
Max. Elevation
Reservoir name
= Pond 1
Max. Storage
Storage Indication method used.
Q (cfs)
100.00
:1 11
•1 11
40.00
20.00
1
Out Pond 1
Hyd. No. 8 -- 100 Year
300 600 900 1200
Hyd No. 8 Hyd No. 3
Wednesday, 07 / 24 12019
= 0.729 ffs
= 50 min
= 75,587 cult
= 30.63 ft
= 87,164 cuft
TOP OF POND = 32.25'
FREEBOARD AT 100-YR = 1.62' Q (cfi
1500 1800 2100 2400 2700
Total storage used = 87,164 cuft
a N11A111111111111111111
80.00
60.01C
40.0C
20.00
a-�a-
3000
Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Hyd. No. 9
Out Pond 2
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 100 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Inflow hyd. No.
= 4 - Post to Pond 2
Max. Elevation
Reservoir name
= Pond 2
Max. Storage
Storage Indication method used.
40
Wednesday, 07 / 24 / 2019
= 0.465 cfs
= 49 min
= 24,277 cult
= 30.77 ft
= 23,603 cult

Hydrograph
Report
41
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Wednesday, 07 / 24 / 2019
Hyd. No. 10
Out Pond 3
Hydrograph type
= Reservoir
Peak discharge
= 0.551 cfs
Storm frequency
= 100 yrs
Time to peak
= 49 min
Time interval
= 1 min
Hyd. volume
= 30,494 cuft
Inflow hyd. No.
= 5 - Post to Pond 3
Max. Elevation
= 30.97 ft
Reservoir name
= Pond 3
Max. Storage
= 29,751 cuft
Storage Indication method used.
Out Pond 3
TOP OF POND = 32.00'
FREEBOARD AT 100-YR = 1.03'

Hydraflow Rainfall Report
45
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v2018.3
Return
Period
Intensity -Duration -Frequency Equation Coefficients (FHA)
(Yrs)
B
D
E
(N/A)
1
0.0000
0.0000
0.0000
-----
2
86.6430
12.8000
0.8789
---
3
0.0000
0.0000
0.0000
------
5
0.0000
0.0000
0.0000
----
10
88.8151
12.4000
0.8031
-- ---
25
78.2208
11.0000
0.7384
50
71.0036
9.7000
0.6904
----
100
69.6549
9.2000
0.6567
----
File name: Swansborol.IDF
Intensity = B / (Tc + D)"E
Return Intensity Values (in/hr)
A.-�J
Friday, 07 / 5 / 2019
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
6.90
5.55
4.66
4.03
3.56
3.19
2.89
2.65
2.45
2.28
2.13
2.00
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
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
10
8.96
7.31
6.22
5.44
4.84
4.38
4.00
3.69
3.43
3.21
3.02
2.85
25
10.10
8.26
7.05
6.20
5.55
5.04
4.63
4.29
4.00
3.76
3.55
3.36
50
11.10
9.07
7.76
6.83
6.13
5.59
5.15
4.79
4.48
4.22
3.99
3.79
100
12.20
10.00
8.59
7.60
6.85
6.26
5.79
5.39
5.06
4.78
4.53
4.31
Tc = time in minutes. Values may exceed 60.
Precio. file name: H:12013\NCC138078\Technical\Storrnwater\Swanshnro_ncn
Storm
Rainfall Precipitation Table (in)
Distribution
I-yF
2-yr
3-yr
5-yr
10-yr
25-yr
50-yr
100-yr
SCS 24-hour
3.65
4.44
0.00
0.00
6.86
8.53
9.98
11.60
SCS 6-Hr
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff -1st
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

BOHLER ENGINEERING NC, PLLC
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Professional Engineering Services Telephone: [phone] Fax: [phone]
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VIA: FedEx
TO: NCDEQ
RE:
Submittal
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_•
ATTN: Christine Hall
DATE:
March 2, 2020
JOB NO:
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IMAR 3 102o
WE ARE SENDING YOU Sho drawin s
❑ p g Copy of letter
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DESCRIPTION
Stormwater Technical Memo
Signed As Built Survey
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