SW8201006_Historical File_20210304

NORRIS & TUNSTALL
CONSULTING ENGINEERS P.C.
2602 Iron Gate Drive,Suite 102 1429 Ash-Little River Road
Wilmington,NC 28412 Ash,NC 28420
[phone] [phone]
[phone] Fax [phone] Fax
John S.Tunstall,P.E. J.Phillip Norris,P.E.
T.Jason Clark,P.E. Joseph K.Bland,P.E.
Thomas J. Scheetz,E.I.
January 25, 2021
NMr.
C S StevenQ G. Pusey, Environmental Engineer II ECEIVE
ll
Division of Energy, Mineral and Land Resources— State Stormwater Program JAN 2 7 2021
127 Cardinal Drive Extension
Wilmington, NC 28405-3845
Re: State Stormwater Project No. SW8 201006
Wilmington Trade Center
4104 US Hwy. 421 North
New Hanover County, NC
N&T Project No. 19131
Dear Mr. Pusey:
Pursuant to your comments of January 12, 2021, we offer the following responses.
1. 15A NCAC 02H.1042(2): Please email the supplement form to the email address
provided below so that it can be preserved electronically per the regulatory
requirements.
Response. We will e-mail you the Supplement Form.
2. 15A NCAC 02H.1042(2)(g)(iii):
A. If there are no surface waters located on this site, please provide confirmation
from the Division of Water Resources and include a note on the plans that none
exist.
Response: The Site Data Table already states, "No Wetlands Exist on the
Site". We have added to the note, "There are no surface waters,
wetlands, regulatory flood zones, protected vegetated setbacks, or
protected riparian buffers within the project boundary".
B. Row 7 of the supplement-EZ cover page indicates that the width of the vegetated
setback is not applicable. Please provide a note on the plans indicating that
there are no surface waters within 50 feet of the project boundary. If a note is
already provided on the plans, please provide a citation of where it is located.

Mr. Steven G. Pusey/NC DEQ Stormwater Dept.
January 25, 2021
Page 2
Response: The Site Data Table already states, "No Wetlands Exist on the
Site". We have added to the note, "There are no surface waters,
wetlands, regulatory flood zones, protected vegetated setbacks, or
protected riparian buffers within the project boundary".
3. 15A NCAC 02H.1050(1) and .1003(3)(b): The design volume of SCMs shall take into
account the runoff at build out from all surfaces draining to the system. Drainage from
off-site areas may be bypassed. If offsite drainage from property not owned by the
applicant or not part of the development project cannot be bypassed, the offsite area
must be considered at its built-out potential or there must be recorded deed restrictions
for BUA between the parties to treat that amount of BUA in the proposed system must
be provided.
The permit application lists a small amount of drainage area as offsite. .
describe where this is located and its impact on the stormwater system.
Response: Please see the revised Drainage Area Map and the Drainage Area
Table showing DA1 and DA2 contains some off-site drainage area
6 n d 4' adjacent to the existing road to the Northwest That is the only off-
site DA to account for in SCM. The other drainage areas shownwith offsite area are for culvert designs in the right-of-way, and do
not go to the SCM's.
4. 15A NCAC 02H.1050(5): SCMs shall include an overflow or bypass device for inflow
volumes in excess of the treatment volume, or, if applicable, the peak attenuation
volume.
A. For the infiltration trench system, the supplement indicates that an overflow or
bypass device has been provided. The plans have a note saying that it is located
at the curb inlets and I found a detail showing that. However, I do not see a
detail showing the SDMH, which is at the center of the trench. If it overflows, will
it lift the manhole cover?
Response: CI-F12, CI-F18 and CI-F23 have emergency overflows towards the
NC DOT right-of-way. The elevation of the overflow is 17.0 feet in
each. The storm drain manholes are not overflow devices. They
collect storm drainage and distribute to the Infiltration Trench. They
also function as observation ports. There are many other curb
inlets with top elevation at or near 17.0 feet. In extreme conditions
water would back up and out of the top of the other curb inlets.
B. For the infiltration basin system, there appears to be two (2) emergency overflow
weirs on Basin 1 but none on Basin 2. I would recommend also putting an
emergency overflow weir on Basin 2 in case the interconnecting pipe gets
clogged.
NCBELS License C-3641

Mr. Steven G. Pusey/NC DEQ Stormwater Dept.
January 25, 2021
Page 3
Response: The emergency spillways have to provide positive flow. They are
placed where positive flow from the basin can occur. If we could
move the second overflow to the area of Basin 2 we would. The
basins function as one with a large equalization pipe. This design
provides the required overflow.
5. 15A NCAC 02H.1051(4): Pretreatment devices shall be provided to prevent clogging.
Pretreatment devices may include. measures such as sumps in catch basins, gravel
verges, screens on roof and patio drains, filters, filter strips, grassed swales, and
forebays. Rooftop runoff that is discharged to the surface of an infiltration system shall
not require pretreatment.
Please advise what type of pretreatment device is provided for the infiltration
basin and the infiltration trench systems. The catch basin detail does not show a
sediment basin, however the drop inlet detail does (where are these)? As
mentioned before, I do not see a detail for the SDMH.
Response: It is noted on the Grading Plans that basin bottom elevations are to
be one (1) foot below the invert out at each curb inlet on the
Grading Plan. Please see details, typical details. They are all
catch basins with differing tops, making them either drop inlets or
curb inlets depending on if they are located in curb and gutter
sections. I believe all on this plan happen to be Curb Inlets,
however we still provide both details. There is a SDMH Detail.
There is one (1) foot of depth below the inverts for sediment
storage. This meets the requirement of the State.
6. 15A NCAC 02H.1051(6): For infiltration devices located under the ground surface, a
minimum of one inspection port shall be provided.
For the infiltration trench, please show the observation port(s) on the plans.
Response: There are 9 SDMH's on the run of the Infiltration Trench. The
SDMH's serve as observation ports that will also allow for
maintenance of the Trench.
Enclosed for your continued review and approval are two (2) sets of revised plans, one (1) set
of revised calculations, the revised Pg. 3 of the Stormwater Permit application, and the revised
pages of the Supplement EZ form (Drainage Areas & Infiltration System). Please note only
revised calculations for the Infiltration Basin are enclosed. The Infiltration Trench calculations
remain unchanged from previous submittal. We will also e-mail you the revised Supplement
Form for your electronic files.
Please let us know if you have any further questions or comments.
NCBELS License C-3641

Mr. Steven G. Pusey/NC DEQ Stormwater Dept.
January 25, 2021
Page 4
Sincerely,
NORRIS & TUNS T ALL
CONSULTING ENGINEERS, P.C.
atIOL\ a �----�
T. Jason i lark, P. E.
TJC/jst/asn
19131 01-25-21-s-sw-response-Itr
Enclosures
NCBELS License C-3641

IIE E 'E ';
J N c i 2,'1'. '.
BY:, �. . ._<...T.
< is>
0
Predeveloped Runoff 1140 Busi ess PArk
Infiltration Basin 1 Ph se 5
A
<2S>
Infiltration Basin 1
Predeveloped Runoff to
Property East of Site S I�W1 �('� I
within Infiltration Basin g'406'' C 10-6"
1 (Sec 5GS gybogeolo9)c,
0i/0tl -t-ton/7o Allow
for Rec1LtCeg& o/1)
c2 ) QiiliQes = licFs
M 5.° -p7S.3GcFs GSo= I456
1 Lj
<Subca) Reach 'on• Llnk Drainage Diagram for 19131 Phase 51 i40 Basin jan 2021
�� Prepared by Norris&Tunstall Consulting Engineers 1/25/21
HydroCAD®7.10 s/n 000479 0 2005 HydroCAD Software Solutions LLC

19131 Phase 51140 Basin jan 2021 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 2
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1 Runoff Area=22.790 ac Runoff Depth=0.00"
Tc=10.0 min CN=36 Runoff=0.00 cfs 0.000 af
Subcatchment 2S: Predeveloped Runoff to Property East of Runoff Area=3.810 ac Runoff Depth=0.00"
Tc=10.0 min CN=36 Runoff=0.00 cfs 0.000 af
Subcatchment 3S: 1140 Business PArk Phase 5 Runoff Area=22.790 ac Runoff Depth>0.58"
Tc=10.0 min CN=89 Runoff=14.33 cfs 1.103 of
Pond 3P: Infiltration Basin 1 Peak Elev=10.60' Storage=2,867 cf Inflow=14.33 cfs 1.103 af
Discarded=10.41 cfs 1.102 af Primary=0.00 cfs 0.000 af Outflow=10.41 cfs 1.102 af
Total Runoff Area=49.390 ac Runoff Volume= 1.103 af Average Runoff Depth =0.27"

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 3
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment IS: Predeveloped Runoff Infiltration Basin 1
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af, Depth= 0.00"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Area (ac) CN Description
22.790 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
1
7�Runoff
Runoff=0.00 cfs
'Type III 24-hr 1.5 inch Storm
Rainfall=1.50"
Runoff Area=22.790;ac
Runoff Volume=0.000 af
.Runoff Depth=0.00"
Tc=10.0 min
CN=36
// / _ / /1//f/%J////!f/JffJ/!////f/fJf/Jf//J//,./7 '
5 6• •7 8 , 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 4
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af, Depth= 0.00"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
/ Hydrograph
p Runoff
Runoff=0.00 cfs
;Type III 24-hr 1.5 inch Storm
Rainfall=1.50"
Runoff Area=3.810 ac
Runoff Volume=0.000 af
Runoff Depth=0.00"
Tc=10.0 min
CN=36
5 6 7• 6 9 10 11 12 • •13• • 14 • 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris &Tunstall Consulting Engineers Page 5
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 14.33 cfs @ 12.15 hrs, Volume= 1.103 af, Depth> 0.58"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Area (ac) CN Description
19.271 98 Bldgs,Asphalt, Concrete
3.519 39 >75% Grass cover, Good, HSG A
22.790 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
16-
157:
- . i 1.,1 Runoff
' Runoff=14.33 cfs
13= Type.III...24-hr.1..5 inch_Storm._
12-
11-
Ra;infaII=1:50"
10 Iunoff'Area=22.790 ac
9� ' Runoff Volume=1.103 af
3
b Runoff Depth>0 58" ..8
3 :�
6
Tc 10.0 min
5= - C N=89 ...
4- , 4
fl
5 6 7 8 9 10 1�1 12 13 14. . ' �15" . '16. ' ' .17' ' . .18� � � '19. . . +20
Time (hours)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 6
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
Inflow Area = 22.790 ac, Inflow Depth > 0.58" for 1.5 inch Storm event
Inflow = 14.33 cfs @ 12.15 hrs, Volume= 1.103 af
Outflow = 10.41 cfs @ 12.27 hrs, Volume= 1.102 af, Atten= 27%, Lag= 7.0 min
Discarded = 10.41 cfs @ 12.27 hrs, Volume= 1.102 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 10.60'@ 12.27 hrs Surf.Area= 29,968 sf Storage= 2,867 cf
Plug-Flow detention time=2.6 min calculated for 1.102 af(100% of inflow)
Center-of-Mass det. time=2.2 min (811.2 - 808.9 )
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismatic)Listed below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store �1 r
(feet) (sq-ft) (cubic-feet) (cubic-feet) .A a ill.�S : '76 ISM
10.50 28,925 0 0 S r
15.00 77,114 238,588 238,588 v luMQ. e. 19.3 5! )q Cc $7($
Device Routing Invert Outlet Devices cP
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Qiscarded OutFlow Max=10.40 cfs @ 12.27 hrs HW=10.60' (Free Discharge)
1=Exfiltration (Exfiltration Controls 10.40 cfs)
primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=10.50' (Free Discharge)
2=Broad-Crested Rectangular Weir(Controls 0.00 cfs)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 7
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
Hydrograph
was f In
.,. flow
114 _ DO Outflow
Inflow Area.=22.790_a.c Discarded0
15= �. r Primary
14-: 1 v 4.3
a
llflo�a--1
13.;. - O-u;tflow=.10.41-Cis
12-:: :
:10.41 d9
� � 10.41 cfe �
1,1 ,.
1. Discarded--=10.41-cfs
r P
9- imary �0 00 cfs
Peak;Elev=10.60'
6- IS .: . :
6E Storage=2,867 cf
.
5 !. ,
4. . .. .
3-
2- si p. !/JJ���. .r�f����= J.�rJ�/yJJJJJ/JJ�JJJ/rl�1dr/
I o.aa ae ' .__.__
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 8
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment IS: Predeveloped Runoff Infiltration Basin 1 Runoff Area=22.790 ac Runoff Depth>0.03"
Tc=10.0 min CN=36 Runoff=0.13 cfs 0.057 af
Subcatchment 2S: Predeveloped Runoff to Property East of S unoff Area=3.810 ac Runoff Depth>0.03"
Tc=10.0 min CN=36 Runoff=0.02 cfs 0.009 af
Subcatchment 3S: 1140 Business PArk Phase 5 Runoff Area=22.790 ac Runoff Depth>3.10"
Tc=10.0 min CN=89 Runoff=74.35 cfs 5.896 af
Pond 3P: Infiltration Basin 1 Peak Elev=12.45' Storage=76,977 cf Inflow=74.35 cfs 5.896 af
Discarded=17.31 cfs 5.892 af Primary=0.00 cfs 0.000 af Outflow=17.31 cfs 5.892 af
Total Runoff Area =49.390 ac Runoff Volume= 5.962 af Average Runoff Depth= 1.45"

19131 Phase 51140 Basin jan 2021 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 9
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Runoff = 0.13 cfs @ 15.69 hrs, Volume= 0.057 af, Depth> 0.03"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type Ill 24-hr 2-yr Rainfall=4.50"
Area (ac) CN Description
22.790 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
0.14= ❑Runoff
Runoff=0.:13 cfs i7
.1acrs
0.11 Type III 24-hr 2-y.rl° r
0.12
�i
j .
0.1-
Rainfall=4.50 ! _
0.09_ Runoff Area=22.790 ac ; i :
1 0.08 Runoff Volume=0.057 af:
0.07 -.
LL 3 Runoff Cepth'>0.03"..;. - .. _ ,
0.06:
0.05
6_ Q.0 .m.i.n... . c _ -
0.04 CN=36 � '..
0.03-i
0.02_ . . . . _.
0.01- 1 ;
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 10
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Runoff = 0.02 cfs @ 15.69 hrs, Volume= 0.009 af, Depth> 0.03"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 2-yr Rainfall=4.50"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 . Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Hydrograph
0.024'
0.023 • El Runoff
3 ..
-looz cfs�
0.02
0i . Runoff=0.02 cfs. : •
, , _
0.02
0%19 1 Type III...24-hr 2-yr
0.017- aiinfati-4.50
0.01651. Runoff
Runoff Volume=0.00. of -
0.013� ,•
Runoff
o.o„- Depth>0.03".
0.014 .. -
0.0091 TO=10.0••rain
0.008;
0.007; . CN=36.. :. . �.
0.0064
0.005=- . -
•o.004 ..
•
0.0034
0.o014 o ,iil/!//J11//!//!/
. , -. ter . , ,
5 6. . . •7 8 • 9 10 11 12 13 14 • • 15, , ,
16, ; , ,17, , , ,18,•. .19, , • •20
Time (hours)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 11
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 74.35 cfs @ 12.14 hrs, Volume= 5.896 af, Depth> 3.10"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 2-yr Rainfall=4.50"
Area (ac) CN Description
19.271 98 Bldgs,Asphalt, Concrete
3.519 39 >75% Grass cover, Good, HSG A
22.790 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
60
°Runoff
75-E
174.35 a.)
70 - Runoff.-74 3-5-cfs.. ...
65E • Type III 24-h r 2=yr
55 ,
Rainfall=4.50".
F 50= Runoff Area=22.790 ac
45_ '
ao-
Runoff.Volume=5..896.af.
LL 35. •
Runoff-Depth>3-.10" _.
30= TO=- �
25
CN=89
20- ._
15
10=
' � 1 ' ` i '
5 6 7 8 9 10 11 12 13 14 15 16 4 17 16 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 12
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
Inflow Area = 22.790 ac, Inflow Depth > 3.10" for 2-yr event
Inflow = 74.35 cfs @ 12.14 hrs, Volume= 5.896 af
Outflow = 17.31 cfs @ 12.59 hrs, Volume= 5.892 af, Atten= 77%, Lag= 26.8 min
Discarded = 17.31 cfs @ 12.59 hrs, Volume= 5.892 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 12.45'@ 12.59 hrs Surf.Area=49,853 sf Storage= 76,977 cf
Plug-Flow detention time=33.1 min calculated for 5.873 af(100% of inflow)
Center-of-Mass det. time=32.7 min (803.0-770.3)
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismatic)Listed below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Qiscarded OutFlow Max=17.31 cfs @ 12.59 hrs HW=12.45' (Free Discharge)
1=Exfiltration (Exfiltration Controls 17.31 cfs)
Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=10.50' (Free Discharge)
2=Broad-Crested Rectangular Weir(Controls 0.00 cfs)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris &Tunstall Consulting Engineers Page 13
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
Hydrograph
- -;. .__ .. ._ �. ----
!, El Inflow
?174.35 cis]
Outflow
Inflow Area=22:790 ac warded
80 p Primary
75 ! I0flow=74,35 cfs
70
,0
65 utflow=17:31 cfs
Discarded=17.31 cfs
50 ' ry=0
Pr..im
45 ak'E Peak 0 40 � � 2.45'
Storage=76,977 cf
17Sfch
25 _ , •
20
10
/Ua, „ //
0.00 efe
0 y,
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin jan 2021 Type 111 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 14
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1 Runoff Area=22.790 ac Runoff Depth>0.48"
Tc=10.0 min CN=36 Runoff=5.36 cfs 0.916 af
Subcatchment 2S: Predeveloped Runoff to Property East of S unoffArea=3.810 ac Runoff Depth>0.48"
Tc=10.0 min CN=36 Runoff=0.90 cfs 0.153 af
Subcatchment 3S: 1140 Business PArk Phase 5 Runoff Area=22.790 ac Runoff Depth>5.44"
Tc=10.0 min CN=89 Runoff=126.31 cfs 10.324 of
Pond 3P: Infiltration Basin 1 Peak Elev=13.87' Storage=158,007 cf Inflow=126.31 cfs 10.324 af
Discarded=22.56 cfs 10.318 af Primary=0.00 cfs 0.000 af Outflow=22.56 cfs 10.318 af
Total Runoff Area =49.390 ac Runoff Volume= 11.393 af Average Runoff Depth = 2.77"

19131 Phase 51140 Basin jan 2021 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 15
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Runoff = 5.36 cfs @ 12.39 hrs, Volume= 0.916 af, Depth> 0.48"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 10-yr Rainfall=7.05"
Area (ac) CN Description
22.790 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1 S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
O Runoff
5.a6
of
Runoff=5.36 s
5-
,
Type III 24-hr 10-yr
Rainfall=7:05"
4
Runoff Area=22.790 ac
Runoff Volume=0:91-6 af
3
LL . Runoff Depth>0.48"
2-'
Tc=10:0 niin
CN=36
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 16
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Runoff = 0.90 cfs @ 12.39 hrs, Volume= 0.153 af, Depth> 0.48"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 10-yr Rainfall=7.05"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Hydrograph
. ...... ...
1 ,
Runoff
Runoff=0.90 cfs
Type;III 24-hr 10-yr
11. Rainfall=7.05"
Runoff Area=3.810 Oc
Runoff,Volume=0.1531 of
LL Runoff Depth>0.48"
Tc=100 min
CN=36
I �
5 6 7 8 9 10 11 12 • 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 17
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 126.31 cfs @ 12.14 hrs, Volume= 10.324 af, Depth> 5.44"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type Ill 24-hr 10-yr Rainfall=7.05"
Area (ac) CN Description
19.271 98 Bldgs,Asphalt, Concrete
3.519 39 >75% Grass cover, Good, HSG A
22.790 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
140-
. F7R off
un
130-
120= Runoff=;12631 cfs
1107 Type III 24-hr 10-yr
Rainfall=7.O
soy
Runoff Area=22.790'ac
S0
Ruhoff.Volume=10.324.af
3 70= u�,
LL 60� � noff Depth> 5:44.
50 Tc=10.0 min....
40- 01 CN=89
30:
20=
101 •�
0Api"opsilifor ,f 't 4.
�f
5 6 7 8 9 10 11 12 4 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 18
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
[82] Warning: Early inflow requires earlier time span
Inflow Area = 22.790 ac, Inflow Depth > 5.44" for 10-yr event
Inflow = 126.31 cfs @ 12.14 hrs, Volume= 10.324 of
Outflow = 22.56 cfs @ 12.65 hrs, Volume= 10.318 af, Atten= 82%, Lag= 30.8 min
Discarded = 22.56 cfs @ 12.65 hrs, Volume= 10.318 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 13.87'@ 12.65 hrs Surf.Area= 64,967 sf Storage= 158,007 cf
Plug-Flow detention time=59.0 min calculated for 10.283 af(100% of inflow)
Center-of-Mass det. time=58.5 min (816.4- 758.0)
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismaticj_isted below(Recaic)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
iscarded OutFlow Max=22.56 cfs @ 12.65 hrs HW=13.87' (Free Discharge)
=Exfiltration (Exfiltration Controls 22.56 cfs)
Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=10.50' (Free Discharge)
2=Broad-Crested Rectangular Weir(Controls 0.00 cfs)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 19
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
Hydrograph
M1 Inflow
l 126.31 chd... 'J Outflow
140 -_- Inflow�Area=22.790 ac P ed
.
inflow=126.31 cfs
-110;" .
Outflow=22:56 cfs
1°0= • Discrdd 2256 -cfs
90= "
P_ _ rirriiaryl 0,00 cf_
I soI
,.
70
Peak Elev 13.87'
•
IT. 60 Stolrage=158007 cf
50=
40' 22.56
_.
30= 2256��
l o
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 20
HydroCAD®7.10 s/n 000479 C 2005 HydroCAD Software Solutions LLC 1/25/21
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Predeveioped Runoff Infiltration Basin 1 Runoff Area=22.790 ac Runoff Depth>0.77"
Tc=10.0 min CN=36 Runoff=10.34 cfs 1.457 af
Subcatchment 2S: Predeveloped Runoff to Property East of SunoffArea=3.810 ac Runoff Depth>0.77"
Tc=10.0 min CN=36 Runoff=1.73 cfs 0.244 af
Subcatchment 3S: 1140 Business PArk Phase 5 Runoff Area=22.790 ac Runoff Depth>6.32"
Tc=10.0 min CN=89 Runoff=145.69 cfs 12.005 af
Pond 3P: Infiltration Basin 1 Peak Elev=14.35' Storage=190,718 cf Inflow=145.69 cfs 12.005 af
Discarded=24.36 cfs 11.998 af Primary=0.00 cfs 0.000 af Outflow=24.36 cfs 11.998 af
Total Runoff Area =49.390 ac Runoff Volume= 13.705 af Average Runoff Depth = 3.33"

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 21
HydroCAD®7.10 sin 000479 ©2005 HvdroCAD Software Solutions LLC 1/25/21
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Runoff = 10.34 cfs @ 12.27 hrs, Volume= 1.457 af, Depth> 0.77"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 25-yr Rainfall=8.01"
Area (ac) CN Description
22.790 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
/ :
11- 0 Runoff
toss us I ;
10. Runoff=l0.' 4 cfs. .
9- type' III. .24-hr 25ryr
8 Rainfall=8:01
7_ ; Runoff Area=22:790 ac
s Runoff:Voluirne=l A57:of
- .
LL 5- Runoff Depth 0.77""
4- Tc.=10.0...rnin
3 / -36
CN
4 -
2 I
0 lAro< 1 ' 2(/ i ,t ' ,... :().'- ll, ' I: ' ' 1 : F (
5 E3• • • •7• • • •8• • • •9• 10 11 •12 13 • • 14 • • 15 • • •16• • • •17 • • •18• • 19 • • 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 22
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Runoff = 1.73 cfs @ 12.27 hrs, Volume= 0.244 af, Depth> 0.77"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 25-yr Rainfall=8.01"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Hydrograph
p Runoff
t.7s as
41; � Runoff=1.73 cfs
Type;III 24-hr 25-yr
Railnfall=8.01"
Runoff =3.
Area810 ;ac
Runoffs Volume=0.244 of
LL Runoff Depth>0.77"
Tc`-100 min
CN=36
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 '20
Time (hours)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 23
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 145.69 cfs @ 12.14 hrs, Volume= 12.005 af, Depth> 6.32"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type Ill 24-hr 25-yr Rainfall=8.01"
Area (ac) CN Description
19.271 98 Bldgs, Asphalt, Concrete
3.519 39 >75% Grass cover, Good, HSG A
22.790 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
160- •
�!R
150; EME1121
140= Runoffi-414569cfs
Type III 4-hi..25=y_
Rainfall=8:0..
110- . . ..
100-• Runoff Area=22:790'ad
90- Runoff.Volume'=12.005 af
Runoff-Depth;>6:32
U. 70-
60 Tc=10.0 'min
40= } y
CN
-89.
30= ;
5 6 7 8 9 10 11 • 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin jan 2021 Type 111 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 24
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
[82]Warning: Early inflow requires earlier time span
Inflow Area = 22.790 ac, Inflow Depth > 6.32" for 25-yr event
Inflow = 145.69 cfs @ 12.14 hrs, Volume= 12.005 af
Outflow = 24.36 cfs @ 12.67 hrs, Volume= 11.998 af, Atten= 83%, Lag= 31.9 min
Discarded = 24.36 cfs @ 12.67 hrs, Volume= 11.998 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 14.35'@ 12.67 hrs Surf.Area= 70,152 sf Storage= 190,718 cf
Plug-Flow detention time=67.8 min calculated for 11.997 af(100% of inflow)
Center-of-Mass det. time=67.5 min (822.6-755.1 )
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data(Prismaticjisted below(Recaic)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
iscarded OutFlow Max=24.35 cfs @ 12.67 hrs HW=14.35' (Free Discharge)
=Exfiltration (Exfiltration Controls 24.35 cfs)
primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=10.50' (Free Discharge)
2=Broad-Crested Rectangular Weir(Controls 0.00 cfs)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 25
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
Hydrograph
0 Oulfiow
Inflow�Area=22.790 ac Discarded
160 i.. .... ..I , ®Primary
150.' , - . .Inflow=145:69 cfs
130 Outflow=24;36 cfs
120- -. -. Discarded=24:36 cfs
,10`
,00 Primary,=0.00 cfs
90 - = 35
- - Peak E�lev 1-4 '
80
LT. 70 Storage=190,718-cf. .
-
x4.36 cis
40
21 z rosy
a.ao�cra Fr.,-
o T f
R -
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 26
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1 Runoff Area=22.790 ac Runoff Depth>1.12"
Tc=10.0 min CN=36 Runoff=18.66 cfs 2.123 af
Subcatchment 2S: Predeveloped Runoff to Property East of Runoff Area=3.810 ac Runoff Depth>1.12"
Tc=10.0 min CN=36 Runoff=3.12 cfs 0.355 af
Subcatchment 3S: 1140 Business PArk Phase 5 Runoff Area=22.790 ac Runoff Depth>7.24"
Tc=10.0 min CN=89 Runoff=165.79 cfs 13.757 of
Pond 3P: Infiltration Basin 1 Peak Elev=14.58' Storage=207,000 cf Inflow=165.79 cfs 13.757 af
Discarded=25.21 cfs 13.015 af Primary=28.69 cfs 0.735 af Outflow=53.90 cfs 13.749 af
Total Runoff Area =49.390 ac Runoff Volume= 16.235 af Average Runoff Depth= 3.94"

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 27
HydroCAD®7.10 s/n 000479 ®2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Runoff = 18.66 cfs @ 12.20 hrs, Volume= 2.123 af, Depth> 1.12"
Runoff by SCS TR-20 method, UH=SCS, Time Span=5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 50-yr Rainfall=9.01"
Area (ac) CN Description
22.790 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
20= (� ee •
0 Runoff
19 :.. do l.. .
18= .Run_off-1-8 66 cfs
16= ' . ..Type:III 24= r
07yr
Rainfall=9.01"
Runoff-Area;22.790
121 ,ac
11
Runoff-.Volume.=2 `1123 of
$ io
Runoff.:Depth-?1.12" _.
8
Tc=10:0 min
CN=36.
_
3'
2'
IS
5 6 7 8 9 10 11 12 • • 13 • • 14 15 • •16 • 17 •18 • 19 • • 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 28
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 2S: Predeveloped Runoff to Property East of Site within infiltration Basin 1
Runoff = 3.12 cfs @ 12.20 hrs, Volume= 0.355 af, Depth> 1.12"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 50-yr Rainfall=9.01"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Hydrograph
Runoff
13.12cfs I
.
3- RLinciff3.12 cfs
Types III 24-hr 50-yr
• I Raififall=9.01"
Runoff Area=3.810-ac
Runoff.Volume=0.355 of
LL Runoff Depth>1.1'2"
Tc 100 min
1 CN=36
I
5 o 7 8 9 10 4 11 12 13 14 15 18 17 18 • 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 29
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 165.79 cfs @ 12.14 hrs, Volume= 13.757 af, Depth> 7.24"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 50-yr Rainfall=9.01"
Area (ac) CN Description
19.271 98 Bldgs, Asphalt, Concrete
3.519 39 >75% Grass cover, Good, HSG A
22.790 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ftt t) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
180="
. ... ... . 0• Runoff
170- 165.79 crs ,
160= • ... Runoff=;16579cfs
150 - - -Type III 24-hr-•50i- r
140
130 • Rainfall=9.01..
R a=2-
920: ._
unoff Are 2:790 ac
110
100= ; Runoff... Volume=13757af
2 90_ -Runoff Depth>7.24"
.
LL 80-E
70= Tc___1
0..0 min
50= • CN=89
40=
30
20= ,
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type 11124-hr 50-yr Rainfall=9.01"
Prepared by Norris &Tunstall Consulting Engineers Page 30
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
[82] Warning: Early inflow requires earlier time span
Inflow Area = 22.790 ac, Inflow Depth > 7.24" for 50-yr event
Inflow = 165.79 cfs @ 12.14 hrs, Volume= 13.757 af
Outflow = 53.90 cfs @ 12.49 hrs, Volume= 13.749 af, Atten=67%, Lag= 21.4 min
Discarded = 25.21 cfs @ 12.49 hrs, Volume= 13.015 af
Primary = 28.69 cfs @ 12.49 hrs, Volume= 0.735 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 14.58'@ 12.49 hrs Surf.Area= 72,595 sf Storage= 207,000 cf
Plug-Flow detention time=66.6 min calculated for 13.748 af(100% of inflow)
Center-of-Mass det. time=66.3 min (819.0-752.7)
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismaticpsted below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
iscarded OutFlow Max=25.20 cfs @ 12.49 hrs HW=14.58' (Free Discharge)
=Exfiltration (Exfiltration Controls 25.20 cfs)
Primary OutFlow Max=28.36 cfs @ 12.49 hrs HW=14.58' (Free Discharge)
2=Broad-Crested Rectangular Weir(Weir Controls 28.36 cfs @ 1.2 fps)

19131 Phase 51140 Basin jan 2021 Type iii 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 31
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
Hydrograph
Xl Inflow
' 165.7a cis CI Outflow
180= ,
` Inflow.Area=22.790: ac miP�aryed
In flow 165:79 cfs
160
150i Outflow=53.90 cfs
, Discarded 26.2'I cfs
130:
P 2
r many : 8.69 cfs
loot .. - Peak Elev=14:58'
ill 80 .1,04 7 Storage=207,000 cf-
70:
60'.
50= ,`
40 l� -,,. _ , ..
30; ! .:
0 Jl f!%ir7. //////f�!�J/J/,/,!„„1", . •�iif
.,. . ..,..'. .�
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 32
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1 Runoff Area=22.790 ac Runoff Depth>1.51"
Tc=10.0 min CN=36 Runoff=28.63 cfs 2.873 af
Subcatchment 2S: Predeveloped Runoff to Property East of RunoffArea=3.810 ac Runoff Depth>1.51"
Tc=10.0 min CN=36 Runoff=4.79 cfs 0.480 af
Subcatchment 3S: 1140 Business PArk Phase 5 Runoff Area=22.790 ac Runoff Depth>8.16"
Tc=10.0 min CN=89 Runoff=185.60 cfs 15.493 af
Pond 3P: Infiltration Basin 1 Peak Elev=14.70' Storage=216,141 cf Inflow=185.60 cfs 15.493 af
Discarded=25.67 cfs 13.861 af Primary=56.06 cfs 1.624 af Outflow=81.73 cfs 15.485 af
Total Runoff Area=49.390 ac Runoff Volume= 18.847 af Average Runoff Depth =4.58"

19131 Phase 5 1140 Basin jan 2021 Type II! 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 33
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Runoff = 28.63 cfs @ 12.18 hrs, Volume= 2.873 af, Depth> 1.51"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 100-yr Rainfall=10.00"
Area (ac) CN Description
22.790 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
32 I I ,
.... .. .._ _ .'.-.. _ _ t.. ... _ I. ........ I ..1..
30 .. 17 Runoff
...I28.63 cfs( •
28 ,Runoff;28r03 cfs26
Type III 24-hr..;100;y
24 r.22
18 Rainfall=10:00"
Runoff Area=22.790.ac
- Runoff,Volume=2973 of
16
1
T. 14
Runoff Depth91:51
12 -
- - : . .. _ T_c .1.0;.0_min.
10 ;
CN=36
6 .
4
.. :2
5 6 7 8 9 10 11 12 13 14 15 • 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 34
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Runoff = 4.79 cfs @ 12.18 hrs, Volume= 0.480 af, Depth> 1.51"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 100-yr Rainfall=10.00"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Hydrograph
i7 Runoff
5 14.79 cfs
{ Runoff=4.79 cfs
4— - f
Type III 24-h r ,100;y r
Rainfall=10.00"
',- ;.. Runoff.Area=3.810.:ac_.
:F 3
' •Runoff Volume=0.480 of
3
Runoff Depth>1.51"
2- Tc=10.0 min
CN=36
1
.•
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 35
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 185.60 cfs @ 12.14 hrs, Volume= 15.493 af, Depth> 8.16"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type Ill 24-hr 100-yr Rainfall=10.00"
Area (ac) CN Description
19.271 98 Bldgs, Asphalt, Concrete
3.519 39 >75% Grass cover, Good, HSG A
22.790 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
.
200=' .- .. _, - • . . ®Runoff
,85.so or.
190'
16o R V 5 .60.Cfs.
off .;18 n.
170' ,
160 Type-III 24-h r;1.00-yr
150 ' ,. Rainfall10:0 0
140'
130' H . ;. - .. Runoff-Area=22.7.90_'ac
120=.
110='
,Runoff;Volume=15493 af:
g 100=� '
E. 90.'
` Runoff Depth>8:16"
80= TC_ 0
.0 Min
70'
9
60
501 :_.- .. _. - 1 �I , .
40'_ '
30=
20='
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin jan 2021 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 36
HydroCAD®7.10 s/n 000479 ©2005 HvdroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
[82]Warning: Early inflow requires earlier time span
Inflow Area = 22.790 ac, Inflow Depth > 8.16" for 100-yr event
Inflow = 185.60 cfs @ 12.14 hrs, Volume= 15.493 of
Outflow = 81.73 cfs @ 12.40 hrs, Volume= 15.485 af, Atten= 56%, Lag= 15.7 min
Discarded = 25.67 cfs @ 12.40 hrs, Volume= 13.861 af
Primary = 56.06 cfs @ 12.40 hrs, Volume= 1.624 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 14.70'@ 12.40 hrs Surf.Area= 73,931 sf Storage= 216,141 cf
Plug-Flow detention time=64.4 min calculated for 15.432 af(100% of inflow)
Center-of-Mass det. time=63.9 min (814.6-750.7)
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismatic Jsted below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
iscarded OutFlow Max=25.67 cfs @ 12.40 hrs HW=14.70' (Free Discharge)
=Exfiltration (Exfiltration Controls 25.67 cfs)
Primary OutFlow Max=55.87 cfs @ 12.40 hrs HW=14.70' (Free Discharge)
,Primary
Rectangular Weir(Weir Controls 55.87 cfs @ 1.5 fps)

19131 Phase 51140 Basin jan 2021 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 37
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
Hydrograph
t _ . ' -185socrs 1 O
I - I - - �Discariled
200. , ;
Inflow;Ar-ea=22.790 ac- III
1904 , L. Inflow=1:85.60. .cfs
170= " - - - . ...Outflow 81.73. :ofs
150 _
1650; 2
=
, Dieters! d 5. .7 cfs
1401
130' ,. Primary=56.06 cfs
g120 ,
110, 73do Peak:Elev=14.70':
3 100 e�. I ,
u. 90 ,� Storage=216,141 cf.-
50= a-
20'
5 6 7 8 r 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin jan 20 NO INFIL Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulti • ••'- --rs
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 1/25/21
Pond 3P: Infiltration Basin 1
[82]Warning: Early inflow requires earlier time span
Inflow Area = 22.790 ac, Inflow Depth > 7.24" for 50-yr event
Inflow = 165.79 cfs @ 12.14 hrs, Volume= 13.757 af
Outflow = 143.33 cfs @ 12.21 hrs, Volume= 9.306 af, Atten= 14%, Lag=4.2 min
Primary = 143.33 cfs @ 12.21 hrs, Volume= 9.306 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 14.98'@ 12.21 hrs Surf.Area= 76,950 sf Storage= 237,410 cf
Plug-Flow detention time=133.9 min calculated for 9.273 af(67% of inflow)
Center-of-Mass det. time=65.6 min (818.3-752.7)
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismatici_isted below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
rimary OutFlow Max=141.98 cfs @ 12.21 h HW=14.9:' ree Discharge)
1=Broad-Crested Rectangular Weir(VVei - - - • s 141.98 cfs @ 2.1 fps)

Date Design NORRIS & TUNSTALJL Wilmington, NC Sheet
10-2-20 —CONSULTING ENGINEERS RC.--- Brunswick County, NC
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NORIIIS & TUNSTA1LL Wilmington, NC Sheet
----CONSULTING ENGINEERS P.C.— Brunswick County, NC
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-Toefi1 re.A4. .A. gas)"/ &n*c v1l' Rasa
Calculate Skimmer Size I
Basin Volume in Cubic Feet 55.758ICu.Ft Skimmer Size 4.0 Inch
Days to Drain* 3 Days Orifice Radius 1.9 Inch(es]
Orifice Diameter 3.8 Inch(es]
in NC mem 3 days to drain
`Estimate Volume of Basin Length Width
Top of water surface In feet Feet VOLUME 0 cu.Ft.
Bottom dimensions in feet _Feet
Depth in feet Feet

Date Dey
NORRIS & TUNSTALL Wilmington, NC Sheet CONSULTING ENGINEERS P.C.— Brunswick County, NC
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Channel Report
Hydraflow Express Extension for Autodesk®AutoCAD®Civil 30®by Autodesk,Inc. Thursday,Oct 8 2020
Swale 1 (5:1)
Triangular Highlighted
Side Slopes (z:1) = 5.00, 5.00 Depth (ft) = 0.27
Total Depth (ft) = 1.50 Q (cfs) = 0.660
Area (sqft) = 0.38
Invert Elev (ft) = 21.00 Velocity (ft/s) = 1.81
Slope (%) = 3.00 Wetted Perim (ft) = 2.75
N-Value = 0.035 Crit Depth, Yc (ft) = 0.26
Top Width (ft) = 2.70
Calculations EGL (ft) = 0.32
Compute by: Known Q
Known Q (cfs) = 0.66
a
Elev (ft) Depth
Section (ft)
23.00 2.00
22.50 --
1.50
22.00
1.00
21.50
0.50
21.00 I 0.00
20.50 i I I I
0 2 4 6 8 10 12 14 18 18 L0 -0.50
Reach (ft)

Channel Report
Hydraflow Express Extension for Autodesk®AutoCAD®Civil 3D®by Autodesk,Inc. Thursday,Oct 8 2020
Swale 1 (5:1)
Triangular Highlighted
Side Slopes (z:1) = 5.00, 5.00 Depth (ft) = 0.28
Total Depth (ft) = 1.50 Q (cfs) = 0.760
Area (sqft) = 0.39
Invert Elev (ft) = 21.00 Velocity(ft/s) = 1.94
Slope (%) = 3.00 Wetted Perim (ft) = 2.86
N-Value = 0.035 Crit Depth, Yc (ft) = 0.28
Top Width (ft) = 2.80
Calculations EGL (ft) = 0.34
Compute by: Known Q
Known Q (cfs) = 0.76
QgC.
Elev (ft) Depth ft
Section p ( )
23.00
2.00
22.50
1.50
22.00
1.00
•
21.50
0.50
21.00 I
0.00
I
I
20.50 I
0 2 4 6 8 10 12 14 16 18 20 -0.50
Reach (ft)

Channel Report
Hydraflow Express Extension for Autodesk®AutoCAD®Civil 3D®by Autodesk,Inc. Thursday,Oct 8 2020
Swale 1 (5:1)
Triangular Highlighted
Side Slopes (z:1) = 5.00, 5.00 Depth (ft) = 0.31
Total Depth (ft) = 1.50 Q (cfs) = 1.000
Area (sqft) = 0.48
Invert Elev (ft) = 21.00 Velocity (ft/s) = 2.08 --
Slope (%) = 3.00 Wetted Perim (ft) = 3.16
N-Value = 0.035 Crit Depth, Yc (ft) = 0,31
Top Width (ft) = 3.10
Calculations EGL (ft) = Q.38
Compute by: Known Q
Known Q (cfs) = 1.00 .- Q
tsa
Elev (ft)
Section Depth (ft)
23.00 2.00
22.50 I 1 1.50
22.00
N"." ' 1.00
21.50
0.50
21.00 I I I I 0.00
I
20.50 I I I 1
0 2 4 6 8 10 12 14 16 18 20 -0.50
Reach (ft)

STORMWATER SYSTEM & EROSION CONTROL CALCULATIONS
WILMINGTON TRADE CENTER
4104 US Hwy. 421 North
Wilmington, North Carolina
For
Seamist Properties, LLC
3807 Peachtree Avenue, Suite 200
Wilmington, NC 28403
[phone]
„d 111 11111 111 1,
11%
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.l ry
7"
EAL rF. 7-4
030869
'Ns'-; ✓ • b„
ry,,y�gsON G\-
n1//1/lUlll l 11 1pp,p1111�„`,`
Revised January 2021 (NC DEQ SW Response)
Revised November 2020 (NHC EC Response)
October 2020
Prepared by:
NORRIS &TUNSTALL CONSULTING ENGINEERS, P.C.
2602 Iron Gate Drive, Suite 102
Wilmington, North Carolina 28412
[phone]
[phone] (Fax) ; ECEIV,
License#C-3641 ., hy9
N&T Project No. 19131

Site Data
Site Area 1,215,263 SF 27.90 AC
IMPERVIOUS SITE TOTAL
BASIN 1
Building: 425,250 SF Building: 425,250 SF
Asphalt,C&G: 413,411 SF Asphalt,C&G: 538,238 SF
Sidewalk: 762 SF Sidewalk: 15,103 SF
Total: 839,423 SF Total: 978,591 SF
Off-Site IMP To Basin 1: 3,345 SF PERCENT SITE IMP: 80.53%
TOTAL TO BASIN 1: 842,768 SF
IMPERVIOUS
TRENCH 1
Building: -
Asphalt,C&G: 124,827 SF
Sidewalk: 14,341 SF
Total: 139,168 SF
TOTAL TO TRENCH 1: 139,168 SF
)ECEIVE
I!.
DIY:

Infiltration Basins
I TOTAL AREA(SF) ASPHALT(SF) CONCRETE CURB SIDEWALK(SF) BUILDING(SF) OFFSITE(SF) IMPERVIOUS %IMPERVIOUS
&GUTTER(SF) TOTAL(SF)
DA1 13,576 9,226 809 0 0 2,565 10,035 74
DA2 65,298 12,251 8,841 0 30,695 5,696 51,787 79
DA6 91659 27400 15072 0 47830 0 90302 99
DA8 80070 22246 14739 0 43100 0 80085 100
DA10 73640 23272 12796 0 36000 0 72068 98
DA12 2850 1382 202 93 0 0 1677 59
DA13 2670 1572 174 32 0 0 1778 67
DA15 3268 1360 210 120 0 0 1690 52
DA16 3093 1590 184 41 0 0 1815 59
DA18 73160 23330 12206 0 35200 0 70736 97
DA20 80000 22238 14747 0 43000 0 79985 100
DA22 78079 21693 14378 0 42020 0 78091 100
DA24 77613 25524 12889 0 37152 0 75565 97
DA26 3290 1350 200 108 0 0 1658 50
DA27 1949 799 118 65 0 0 982 50
DA29 4515 1350 200 182 0 0 1732 38
DA30 2676 802 119 121 0 0 1042 39
DA32 75823 25532 12377 0 34618 0 72527 96
DA34 78082 21700 14400 0 42000 0 78100 100
DA36 67861 23513 10620 0 33635 0 67768 100
DA41 84095 0 0 0 0 0 0 0
DA42 29274 0 0 0 0 0 0 0
TOTAL(SF) 992,541 268,130 145,281 762 425,250 8,261 839,423 84.6
TOTAL(AC) 22.79 6.16 3.34 0.02 9.76 0.19 19.271
•'On the Plans the Basin is split into two basins,Basin 1 and 2.They function as one Basin.
*DA1 INCLUDES 2565 SF OF OFFSITE AREA WITH 2565 SF BEING IMPERVIOUS(ROW ACCOUNTED FOR IN INFILTRATION BASIN)
•DA2 INCLUDES 5696 SF OF OFFSITE AREA WITH 7Rn cF BEING IMPERVIOUS(ROW ACCOUNTED FOR IN INFILTRATION BASIN)
INCcu©S
17A- ONSITE = �1S ZSQsF/Zz G,4c
3 gyssr
Or&s)7c = e zC i 5F / o.19 Ac,
(OFF-SIT )
TM ? ONStrg t Q3G,0'78sFAc .iggA
0 Fr 1,,C.7 3,3'1Ssp j O'77,1
OECEWEi
BY:

. • RV6 3QA 2oz i
Date Design NORRIS & TUNSTALL Wilmington, NC Sheet
CONSULTING ENGINEERS P.C.— Brunswick County, NC
Of
Check Job For Job No.
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--CONSULTING ENGINEERS P.C.----- Brunswick County, NC
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Pusey, Steven
From: Pusey, Steven
Sent: Tuesday,January 12, 2021 2:27 PM
To: Ken Dull ([e-mail]);Jason Clark([e-mail]); Pete
Avery([e-mail])
Subject: Stormwater permit SW8 201006 -Wilmington Trade Center/Request for Additional
Information
Attachments: 2021 01 addinfo 201006.pdf
Gentlemen:
Please reference the attached letter requesting additional information for subject project.
I look forward to your response. Let me know if you have any questions.
Best regards,
Steven G. Pusey
Environmental Engineer II
Division of Energy, Mineral and Land Resources
State Stormwater Program
North Carolina Department of Environmental Quality
127 Cardinal Drive,Wilmington, NC 28405
Office: [phone]
Direct: [phone]
Email: [e-mail]
D E ))
!c ar.7 j"{... '4ress:s
•i ::Cat 7::fna,�:i'u:'�r?_ i�rcL L',w G;)i]:'; .y oc t S J 2u is :1 pi;des.
1

ROY COOPER ,(('' "1 ;}
Governor YM}i # .,
�QVV9911 :.`-. YF
MICHAEL S.REGANv.t r ;�
i 'fin •
Se ctelpry ` }� t
BRIAN WRENN NORTH CAROLINA
Director EAr m[ y
January 12,2021
Via email only: kdull(a)mckinleybuildinQ com
Seamist Properties,LLC
Attn: Ken Dull,Manager
3807 Peachtree Avenue, Suite 200
Wilmington,NC 28403
Subject: Request for Additional Information
Stormwater Project No. SW8 201006
Wilmington Trade Center
New Hanover County
Dear Mr. Dull:
The Wilmington Regional Office received and accepted a State Stormwater Management Permit Application for
the subject project on October 13,2020. A preliminary in-depth review of that information has determined that
the application is not complete and that additional information is needed. To continue the review,please provide
the following additional information in a hard copy submittal package:
1. 15A NCAC 02H.1042(2): Please email the supplement form to the email address provided below so that
✓ it can be preserved electronically per the regulatory requirements.
2. 15A NCAC 02H.1042(2)(g)(iii):
Va. If there are no surface waters located on this site,please provide confirmation from the Division
of Water Resources and include a note on the plans that none exist.
7 b. Row 7 of the supplement-EZ cover page indicates that the width of the vegetated setback is not
applicable. Please provide a note on the plans indicating that are no surface waters within 50 feet
of the project boundary. If a note is already provided on the plans,please provide a citation of
where it is located.
3. 15A NCAC 02H.1050(1)and.1003(3)(b): The design volume of SCMs shall take into account the runoff
at build out from all surfaces draining to the system. Drainage from off-site areas may be bypassed. If
offsite drainage from property not owned by the applicant or not part of the development project cannot
be bypassed,the offsite area must be considered at its built-out potential or there must be a recorded deed
restriction for BUA between the parties to treat that amount of BUA in the proposed system must be
provided.
The permit application lists a small amount of drainage area as offsite. Please describe a+here this
/ is located and its impact on the storm water system.
4. 15A NCAC 02H.1050(5): SCMs shall include an overflow or bypass device for inflow volumes in excess
of the treatment volume,or,if applicable,the peak attenuation volume.
a. For the infhration trench system,the stppiemeni indicate:that an overflow or bypass device h:,s
been provided. The plans have a note saying that It is located at the curb inlets any;I found a
detail showing that. However, l do not see a detail showing the SDK-I. which is at the center of
the trench. If it overflows,will it lift the m<.nl.ole cover?
North Comtua Denartment cat Environmental Quaiiry Diviiion i t Energy heneval met Lard'triourt e.
iel Wilmington itegianat Offier is Can lnai Chive E ztensio t Wilmington,"i onth Cwolina3„MgtS

State Stormwater Permit No.SW8 201006
Page 2 of 2
b. For the infiltration basin system.there appears to he two(2) emergency overflow weirs on Basin
I but none on Basin 2. 1 would recommend also putting an emergency overflow weir on Basin 2
in case the interconnecting pipe gets clogged.
5. 15A NCAC 02H.1051(4): Pretreatment devices shall be provided to prevent clogging.Pretreatment devices may
include measures such as sumps in catch basins,gravel verges,screens on roof and patio drains,filters,filter strips,
grassed swales,and forebays. Rooftop runoff that is discharged to the surface of an infiltration system shall not
require pretreatment.
Please advise what type of pretreatment device is provided for the infiltration basin and the
infiltration trench systems. The catch basin detail does not show a sediment basin, however the
drop inlet detail does (where are these?). As mentioned before, I do not see a detail for the
SDMH.
✓ 6. 15A NCAC 02H.1051(6): For infiltration devices located under the ground surface,a minimum of one
inspection port shall be provided.
For the infiltration trench, please show the observation port(s)on the plans.
Please remember to confirm that any revised information is presented consistently throughout the application
documents including calculations,supplements,narrative,and plans. Please also remember to provide two (2)
hard copies of any updated documents per 15A NCAC 02H.1042(2).
All of the requested information listed above should be received in this Office by January 28,2020,or the
application will be returned as incomplete. If additional time is needed to submit the requested information,
please email your extension request prior to this due date to the email address provided below with a justification
and a date of when the requested information will be submitted,which shall be no later than 15 days past the
original due date.Please note that only two letters requesting additional information is allowed in the State
Stormwater Program for a total of 30 days to submit the requested additional information. If the information is
not satisfactorily provided after either the second request or 30 days, the project will be returned. If the project is
returned and you wish to re-submit later,you will need to resubmit all required items at that time, including the
application fee.
The construction of any impervious surfaces,other than a construction entrance under an approved Sedimentation
Erosion Control Plan, is a violation of NCGS 143-215.1 and is subject to enforcement action pursuant to NCGS
143-215.6A.
Please reference the State assigned project number on all correspondence. If you have any questions concerning
this matter,please feel free to call me at(910)796-7215 or email me at [e-mail].
Sincerely,
s P
Steven G.Pusey
Environmental Engineer II
DES/sgp: \\\Stormwater\Permits&Projects\2020\201006 HD\2021 01 addinfo 201006
cc: Jason Clark, PE—Norris&Tunstall;via email:jclarkAntent'ineers.com
Pete Avery, via email: paver�w,nckinleybuilding com
Wilmington Regional Office Stormwater File

Burd, Tina J
From: Burd, Tina J
Sent: Friday, October 16, 2020 3:05 PM
To: [e-mail]; [e-mail];John Tunstall;Amy Norris
Subject: SW8 201006 -Wilmington Trade Center
The Wilmington Regional Office of the Division of Energy, Mineral and Land Resources(Stormwater Section)accepted
the Stormwater Permit Application and$505.00 fee for the subject project on October 13, 2020. The project has been
assigned to Steven Pusey and you will be notified if additional information is needed. Please be advised that the
construction of built-upon area may not commence until the Stormwater Permit is issued.
Best Regards,
Tina Burd
Administrative Associate II
Wilmington Regional Office
Division of Environmental Assistance&Customer Service
Phone [phone]
NCDEQ
Wilmington Regional Office
127 Cardinal Drive Ext.
Wilmington, NC 28405
Email corrr','vl`):r:ile12.o v1'. . r. .. i i'i " L) the
wr ih Carolina
1

Application Completeness Review Checklist(Non-Transfers)-Short Version
Project Name: 1 I L r-'i r f.G f 0 N T Li UCcE. 13 7t; le Date Delivered to W IRO: /b+,kJ/2c 2 u
Project County/Location: M Gr,3 E-(A a0 L,+C L. l4{34 J S i 7 Q 11-1 RIMS Received/Accented Date: is �j�Zc)
L J Rule(s): 02017 Coastal 02008 Coastal E. S Coastal BIMS Acknowledged Date:: /—
DPhase II Eurtiversal 01988 Coastal
1 Permit Action: Ne� New Permit#2: S 64 ;O / 00
Major Mod/Minor Mod/Renewal Existing Permit#:
Permit Type: HD i LD I LD Overall/-ID&LD Combo Expriation Date :
General Permit i Offsite I Exempt/Rescission EOffsite to SWB:
Development Type: Commercial Residential I Other Lot is in Master Permit?
Subdivided?: Subdivision or Single Lot OPE Cert on File?
Permittee Type&Documents Needed:
Property Ownerls) Purchaser Lessee EHO�+ �Deveiooer
'Jiabie? �tiiabie? Viable? EViabie? DViable?
Deed OPurchase Agmt ELease Election ,vilcriutes
Not Subdivided: Deed
E5ubcPkos:on• Common Area Deed
Paperwork
r A.plication
Fee. 125505(wrthrn Gmo) Cherk#(s): 14:,' G, ENo Fee
i aupplement'r(1 new form or for older forms:1 original per SCM)
a&M2
Soils Report(Infil or PP)
Calculations(signed/sealed)
❑Deed Restrictions, if subdivided/
MProject Narrative
EIL15GS Map(or on fife?) Subject to SA?: Y /0 Subject to ORW? Y /'✓
12Plans(2 Sets)
EPE Certification
1ZElectronic Copies
,E1 Easements, Recorded(2017 Rules)
• NOTES:
, 1Enter RIMS Acknowledged Date on this Sheet
2For New Projects-Enter New Permit#on Supplements& Deed Restiction Templates.
3lf w/in 6 months and they are requesting a mod,STOP. Needs a renewal first.
EMAILED ENGINEER DATE: Comments:
REVIEWER NAME: jTEUs
.e?erence Library\Procer.tt, \Caecklists\Completeness Review Ci;ecklisr_2020 01 31

NORRIS & TUNSTALL
CONSULTING ENGINEERS P.C.
2602 Iron Gate Drive,Suite 102 1429 Ash-Little River Road
Wilmington,NC 28412 RECEWED Ash,NC 28420
[phone] [phone]
[phone] Fax [phone] Fax
iOCT I 3 120
John S.Tunstall,P.E. J.Phillip Norris,P.E.
T.Jason Clark,P.E. NCOEQ Joseph K.Bland,P.E.
WILMINGTON RO Thomas J. Scheetz,E.I.
October 12, 2020
NC DEQ
Division of Energy, Mineral and Land Resources — State Stormwater Program
127 Cardinal Drive Extension
Wilmington, NC 28405-3845
Re: State Stormwater Permit Submittal
Wilmington Trade Center
4104 US Hwy. 421 North
New Hanover County, NC
N&T Project No. 19131
Dear Sir or Madam:
Enclosed are two (2) sets of plans for the above referenced project, one (1) set of calculations
(which includes the soils report), one (1) copy of the Stormwater Narrative, one (1) USGS map,
one (1) copy of the Deed, one (1) copy of the Articles of Organization, the original Division of
Water Quality Stormwater Management Permit application, the original Supplement EZ form,
the original Operation and Maintenance EZ Agreement, a $505.00 check for the permit review
fee, and one (1) CD (PDF of the complete submittal).
Please review this information for approval and contact us with any questions or comments
you may have. Thank you for your assistance on this project.
Sincerely,
NORRIS & TUNSTALL
CONSULTING ENGINEERS, P.C.
EDL O
T. Jaso Clark, P. E.
TJC/jst/asn 19131 10-12-20-s-sw-Itr
Enclosures
cc: McKinley D. Dull, Manager/Seamist Properties, LLC (by E-Mail Only)
Pete Avery/ McKinley Building (by E-Mail Only)
NCBELS License C-3641

STORMWATER SYSTEM & EROSION CONTROL NARRATIVE
WILMINGTON TRADE CENTER
4104 US Hwy. 421 North
Wilmington, North Carolina
For
Seamist Properties, LLC
3807 Peachtree Avenue, Suite 200
Wilmington, NC 28403
[phone]
, 1011111/ 1 ...i.s.44:00,1e,
,.
..,,▪ , /04.,....ekst.
, „:., f 03 08
SEAL i
69
S NG
October 2020
Prepared by:
NORRIS &TUNSTALL CONSULTING ENGINEERS, P.C.
2602 Iron Gate Drive, Suite 102
Wilmington, North Carolina 28412
[phone]
[phone] (Fax)
/�`�C T4
License# C-3641 (,r { 4x
N&T Project No. 19131 e1• I �6� * r r"

NARRATIVE
WILMINGTON TRADE CENTER
Receiving Stream Name: NE Cape Fear River
Stream Class: SC; SW
Stream Index Number: CFP17 18-74-61
DESCRIPTION:
The project site is a 27.899± AC tract located at 4104 US Hwy. 421 North in
Wilmington, NC. The soils of the site consist of highly permeable Sandy Soils with grades
ranging from 10% (NW Property Line) to 0%. Approximately 29.3 AC will be graded to
allow construction of the Wilmington Trade Center, which consist of three (3) buildings
with paved parking and paved access. The runoff from the site is estimated using the
rational method for the required design storms and rainfall data for the area. Construction
is scheduled to begin as soon as all permits and approvals are obtained.
EROSION CONTROL MEASURES:
The attached plans and specifications outline the requirements for erosion control
measures. Silt fencing will be provided along each side of the entrance drive where
stormwater would be expected to sheet flow from disturbed areas directly to adjacent
property. Gravel check dams will not be provided unless the contractor has to temporarily
discharge into an open ditch instead of the proposed storm drain outfall. There are two
(2) Stormwater SCM's designed for the site. One (1) is an Infiltration Basin (NE Property
Line — Rear of the Buildings) that will function as a sediment basin during construction.
The front of the site drains into a subsurface Infiltration Trench for stormwater treatment.
During construction, sediment will not be allowed to enter the system. The inlets for the
Infiltration Trench will be protected with silt sacks and hardwire and rock inlet protection.
Erosion control in this area will be accomplished with the inlet protections. Along the
perimeter erosion control is accomplished with temporary silt fence. The provided tsf is
above the required minimum of 400 If/AC. Rip-rap energy dissipaters are sized
appropriately at all storm drainage outlets. Along the NW property line there is a roadside
swale that will include 12" diameter Wattles to decrease velocity and provide erosion
control. A gravel construction entrance will be constructed at all entrances. Maintenance
will be provided by the grading contractor and developer.
STORMWATER MANAGEMENT MEASURES:
The project site is located in New Hanover County. Land disturbing on the site will
exceed one (1) acre, which requires the site to comply with NHC and State regulations.
The stormwater runoff from the development will be directed to the two (2) infiltration
systems. The first is a large Infiltration Basin (Made up of Basins 1 and 2 per the plans,
act as one basin) and the second is an Underground Infiltration Trench. ECS provided a
Hydrogeologic Analysis of the site and soils to allow for the infiltration basin to reduce the
2

required separation between the basin and the SHWT from 2 feet to 1 foot. Per NHC
Requirements the site meets the Pre-Post Requirements for the 2, 10 and 25-year storms.
CONSTRUCTION SEQUENCE:
The contractor will install the gravel construction entrance(s) and silt fence prior to
beginning any clearing and grading operations. Additional silt fence will be installed when
and if conditions warrant during construction. The Infiltration basin/sediment basin will be
constructed immediately after that portion of the site is cleared, and outlet structure with
protection will be installed. Disturbed areas will be landscaped or seeded or sodded upon
completion.
3

EROSION CONTROL NOTES AND MAINTENANCE PLAN
1. All erosion and sediment control measures will be checked for stability and
operation following every runoff-producing rainfall, but in no case, less than once
every week and within 24 hours of every half-inch rainfall.
2. All points of egress will have construction entrances that will be periodically top-
dressed with an additional 2 inches of#4 stone to maintain proper depth. They
will be maintained in a condition to prevent mud or sediment from leaving the site.
Immediately remove objectionable material spilled washed or tracked onto the
construction entrance or roadways.
3. Sediment will be removed from hardware cloth and gravel inlet protection, block
and gravel inlet protection, rock doughnut inlet protection and rock pipe inlet
protection when the designed storage capacity has been half filled with sediment.
Rock will be cleaned or replaced when the sediment pool no longer drains as
designed. Debris will be removed from the rock and hardware cloth to allow proper
drainage. Silt sacks will be emptied once a week and after every rain event.
Sediment will be removed from around beaver dams, dandy sacks and socks once
a week and after every rain event.
4. Diversion ditches will be cleaned out immediately to remove sediment or
obstructions from the flow area. The diversion ridges will also be repaired. Swales
must be temporarily stabilized within 21 calendar days of cease of any phase of
activity associated with a swale.
5. Sediment will be removed from behind the sediment fence when it becomes half
filled. The sediment fence will be repaired as necessary to maintain a barrier.
Stakes must be steel. Stake spacing will be 6 feet max. with the use of extra
strength fabric, without wire backing. Stake spacing will be 8 feet max. when
standard strength fabric and wire backing are used. If rock filters are designed at
low points in the sediment fence, the rock will be repaired or replaced if it becomes
half-full of sediment, no longer drains as designed or is damaged.
6. Sediment will be removed from sediment traps when the designed storage
capacity has been half filled with sediment. The rock will be cleaned or replaced
when the sediment pool no longer drains or when the rock is dislodged. Baffles
will be repaired or replaced if they collapse, tear, decompose or become
ineffective. They will be replaced promptly. Sediment will be removed when
deposits reach half the height of the 1st baffle. Floating skimmers will be inspected
and kept clean weekly.
7. Sediment will be removed from the sediment basin when the design storage
capacity has been half filled with sediment. Rock will be cleaned or replaced when
the sediment pool no longer drains or if the rock is dislodged. Baffles will be
repaired or replaced if they collapse, tear, decompose or become ineffective. They
will be replaced promptly. Sediment will be removed from baffles when deposits
4

reach half the height of the 1st baffle. Floating skimmers will be inspected weekly
and will be kept clean.
Land Quality Requires:
8. All seeded areas will be fertilized, reseeded as necessary and mulched according
to specifications in the vegetative plan to maintain a vigorous, dense vegetative
cover. All slopes will be stabilized within 21 calendar days. All other areas will be
stabilized within 15 working days.
Water Quality Requires:
9. All seeded areas will be fertilized, reseeded as necessary and mulched according
to specifications in the vegetative plan to maintain a vigorous, dense vegetative
cover. All perimeter dikes, swales, ditches, perimeter slopes, all slopes steeper
than 3' horizontal to 1' vertical (3:1) and all high quality water (HQW) zones shall
be provided temporary or permanent stabilization with ground cover as soon as
practicable but in any event within seven (7) calendar days from the last land-
disturbing activity. All other disturbed areas shall be provided temporary or
permanent stabilization with ground cover as soon as practicable but in any event
within fourteen (14) calendar days from the last land-disturbing activity.
10. Flocculants will be used to address turbidity issues. The pumps, tanks, hoses and
inject systems will be checked for problems or turbid discharges daily.
11. Refer to new NPDES rules regarding basin outlet structures and skimmers shall
withdraw water from the surface.
5

SECTION 02920
SOIL EROSION AND SEDIMENTATION CONTROL
1. GENERAL
1.1 Contractor shall take every reasonable precaution throughout construction to prevent
the erosion of soil and the sedimentation of streams, lakes, reservoirs, other water
impoundments, ground surfaces, or other property as required by State and Local
regulations.
1.2 The Contractor shall install all required silt fences, and construction entrances at the
initiation of work, and have these measures reviewed and approved by the local
permit authority prior to clearing and grading operations.
1.3 The Contractor shall, within 21 days of suspension or completion of land disturbing
activities, provide permanent protective covering for disturbed areas. Temporary and
permanent erosion control measures shall be coordinated to assure economical,
effective, and continuous erosion and siltation control throughout the construction
and post-construction period. Use the specified seed for both temporary and
permanent seeding.
2. PRODUCTS
2.1 Asphalt for anchoring mulch shall be Type SS-1 Emulsion.
2.2 Fertilizer shall be 10-10-10 grade or equivalent.
2.3 Lime shall be dolomitic agricultural ground limestone containing not less than 10
percent magnesium oxide.
2.4 Mulch shall be small grain straw, hay, wood chips, asphalt emulsion, jute or other
suitable material free of undesirable weed seed.
2.5 Phosphate shall be 20 percent superphosphate or equivalent.
2.6 Seed shall be 20% carpet grass, 24% Bermuda, 20% turf Fescue, 10% Creeping
Red Fescue, and 24% Annual Rye grain. Bermuda seed shall be hulled for warm
weather planting and unhulled for cool weather planting. Purity of seed shall be a
minimum of 98 percent and germination shall be a minimum of 85 percent.
2.7 Silt fence shall consist of NCDOT Class A fabric supported by metal posts spaced
not more than 6 feet on center. The bottom of the fabric shall be buried a minimum
of 6 inches.
2.8 Gravel for check dams shall be#57 washed stone.
2.9 Aggregate for construction entrance shall be#4 washed stone.
6

2.10 Stone rip rap for check dams and erosion control shall be NCDOT Class A or B as
shown.
3. EXECUTION
3.1 General: Take every practicable measure during construction or suspension to work
to minimize erosion and siltation. Measures should include good construction
practices, temporary physical barriers to sediment travel, settling basins for new
ditches, and establishment of vegetative cover.
3.2 Construction Practices
3.2.1 Avoid dumping soil or sediment into any wetland or watercourse.
3.2.2 Maintain an undisturbed vegetative buffer where possible between a natural
watercourse and trenching and grading operations.
3.2.3 Avoid equipment crossings of streams, creeks, and ditches where practicable.
3.2.4 Grade all cut, fill and ditch slopes to minimum slope of 3:1, unless otherwise shown
or directed.
3.3 Temporary Physical Barriers are required where sedimentation on offsite property or
excessive erosion is a problem.
3.3.1 Mulch shall be used for temporary stabilization of areas subject to excessive erosion
and for protection of seedbeds after planting where required.
1. Apply grain straw and hay at a rate of 75 to 100 pounds per 1,000 square feet
and wood chips at a rate of 500 pounds per 1,000 square feet. Jute and mesh
should be installed as per manufacturer's instructions.
2. Asphalt emulsion for slope stabilization should be applied at a rate of 1,000
gallons per acre. Asphalt emulsion used for anchoring straw should be applied
at a rate of 150 gallons per ton of straw.
3.3.2 Silt Fences shall be used at the base of slopes to restrict movement of sediment
from the site. Clean silt fence of accumulated sediment after each rainfall event or
when it exceeds a depth of 0.5 feet above natural grade.
3.3.3 Stone Check Dams, placed at the discharges of creeks, ditches, and swales, shall
consist of Class A or Class B erosion control stone at minimum two feet high and
three feet thick across the watercourse, with a one foot thick iayer of gravel on
upstream side. Remove sediment if accumulated to a depth of 1.0 feet at upstream
face.
7

•
3.4 Vegetative Cover: Establish and maintain permanent vegetative cover on all
unpaved areas disturbed by the work.
3.4.1 Preparation of Seedbed: Areas to be seeded shall be scarified to a depth of 4 inches
and until a firm, well pulverized, uniform seedbed is prepared. Lime, phosphorous
and fertilizer shall be applied during the scarification process in accordance with the
following rates:
Lime: 45 pounds per 1000 square feet
Phosphorous: 20 pounds per 1,000 square feet
Fertilizer: 17 pounds per 1000 square feet
3.4.2 Seeding: Disturbed areas shall be seeded with 2 to 3 pounds per 1000 square feet
of the specified seed mixture. Seed shall be worked into the bed to a depth of 1/4
inch. Regrade and seed eroded areas immediately
3.4.3 Mulch all areas immediately after seeding. Mulch shall be applied and anchored as
specified hereinbefore. Reapply as necessary to retain cover until grass is
established.
3.5 Construction Entrance: Provide an aggregate drive, 20 feet wide by 50 feet long by
6 inches thick at each entrance to the site used by construction vehicles, until such
time as the permanent roadway is constructed. Remove soil if accumulated to a
depth greater than 0.5 inches.
3.6 Maintenance: The Owner and Contractor shall be responsible for maintaining all
temporary and permanent erosion control measures. Temporary structures shall
be maintained until such time as vegetation is firmly established in the area
protected by the structure. Permanent streambank protection and grassed areas
shall be maintained until completion of the project. Areas that fail to show a
suitable stand of grass or which are damaged by erosion shall be immediately
repaired.
END OF SECTION
8

DRAINAGE AREAS
1 Is this a high density project? Yes
2 If so,number of drainage areas/SCMs 2
Is all/part of this project subject to previous rule -1
3 versions? No i
FORMS LOADED
DRAINAGE AREA INFORMATION 1 Entire Slte I 1 2
I i —IF UG Infiltration
4 Type of SCM N/A _ ' Infiltration Basin Trench k--_
5 Total BUA in project(sq ft) 974556 sf 835388 sf r 139168 sf
New BUA on subdivided lots(subject to permitting)F (_ ,
6 (sq ft) �_ 0 sf 'I 0 sf 0___
_sf _
New BUA outside of subdivided lots(subject to t• '�I'� �� ��
7 permitting)(sf) ' 974556 sf i' 835388 sf_ 139168 sf .1
8 Offsite-total area(sq ft) 4852 sf 4852 sf 0 sf II
9 Offsite BUA(sq ft) •I" 0 sf 1 ,^0 sf—_______ —_,0 sf �_
11'
10 Breakdown of new BUA outside subdivided lots: ' I( 4 j
-Parking(sq ft) 383610 sf J,a 265565 sf r._ 118045 sf l
-Sidewalk(sq ft) 15103 sf 762 sf I 14341 sf_
-Roof(sq ft) 423780 sf ,' 423780 sf �_ �0 sf 1
-Roadway(sq ft) I __ g...0___ i� 0 sf__ 0 sf
Future(sq ft) 0 sf �I O sf r 0 sfr
-Other,please specify i the omm b ! .i 'I I
below(sq ft) I,u,r�4, 1jr 152063 sf I 145281 sf 6782 sf II
New infiltrating permeable pavement on
11 subdivided lots(sq ft) L0 sf 'I---
New 0 sf 0 sf I
infiltrating permeable pavement outside of I ���(
12 subdivided lots(sq ft) I 0 sf ; 0 sf I 0 sf
Exisitng BUA that will remain(not subject to 11— —�
13 permitting)(sq ft) F__, 0 sf__,._,_,� _ 0 sf B 0 sf l
14 Existing BUA that is already permitted(sq ft) 0 sf _ i 0 sf 0 sf __.
15 Existing BUA that will be removed(sq ft) - 0 sf .r 0 sf ___ 0 sf_
16 Percent BUA L 809(uPr+ -% 0%
17 Design storm(inches) Is_ 1.5 in I 1.5 in 1.5 in _I
18 Design volume of SCM(cu ft) 1 0 cf ji�100112 cf 16618 cf _ I
_
19 Calculation method for design volume � . Simple___II Simple_____, Simple_ 1
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the
20 drainage area(s):
i ► 4". 164CPC4 sea, r
E c,
8
BY

INFILTRATION SYSTEM
1 - Drainage area number 1(Basin) 1__2(Trench)
2 Design volume of SCM(cu ft) L_100112 cf——II 16618 cf -_
GENERAL MDC FROM OM.1050 +--
_^--3 Is the SCM sized to treat the SW from all surfaces at build-out? Yes Yes4 Is the SCM located away from contaminated soils? Yes _ Yes �y-
5 What are the side slopes of the SCM(H:V)? 3.1 1 1
6 Does the SCM have retaining walls,gabion walls or other engineered side slopes? _No E,�_ No
7 Are the inlets,outlets,and receivingstreamprotected from erosion(10-year storm)? i Yes ��'r 1
( Ye _ I Yes ___i
8 Is there an overflow or bypass for inflow volume in excess of the design volume? Yes Yes
9 What is the method for dewatering the SCM for maintenance? Pump(preferred) Pump(preferred) I
10 If applicable,will the SCM be cleaned out after construction? Yes ± Yes 1
____.
11 Does the maintenance access comply with General MDC(8)? _ Yes _ - Yes— -1
12 Does the drainage easement comply with General MDC(9)? Yes Yes )
If the SCM is on a single family lot,does(will?)the plat comply with General MDC _ -'�
13 (10)? _ N/A__ _ N/A _
14 Is there an O&M Agreement that complies with General MDC(11)? __Yes I _Yes
15 Is there an O&M Plan that complies with General MDC(12)? Yes — Yes
16 Does the SCM follow the device specific MDC? L---_--w--,---� r-- Yes it
17 Was the SCM designed by an NC licensed professional? Yes jr.. Yes
NFILTRATIgN M,MDCFROMo3H,,05,4
18 Proposed slope of the subgrade surface(%) 0% — 0% _—_
19 Are terraces or baffles provided? 1 No _1r No fl
1 ,
20 Type of pretreatment: Sump©DI 11Sump ia DI -4(ZInvio `� W SISOIIS DOtO _,_—� e Was the soil investigated in the footprint and at the elevation of the infiltration 74 •,
-,\
21 system? Yes Yes
22 SHWT elevation(fmsl) 9.50 9.81
23 Depth to SHWT per soils report(in) W *69.57 id
*50 _1
24 Ground elevation at boring in soils report(fmsl) 15.30 1 _ 13.97
25 Is a detailed hydrogeologic study attached if the separation is between 1 and 2 feet? ® Yes No �1
26 Soil infiltration rate(in/hr) 24.92 14.44 _
27 Factor of safety(FS) (2 is recommended): 1.66 �2,00�� _
Elevations — ----
29 Bottom elevation(fmsl) 10,5 ft _ 12 ft _
30 Storage elevation(fmsl) - 1485 ft 17 ft
31 Bypass elevation(fmsl) 14.35 ft 17 ft
For Basins Only_ ____________1___' _
32 Bottom surface area,ft2: _ - —�_28925ft T_ �-
N/A • 1
33�Storage elevation surface area(ft2) W— 70150 ft 0 - N/A
[For Trenches Only
34 Length(ft) N/A 1990 ft
35 Width(ft) N/A 7.5 ft
36 Perforated pipe diameter,if applicable(inches) N/A 36 in
37 Number of laterals N/A 1
38 Total length of perforated piping N/A 1990 ft
39 Stone type,if applicable N/A #57
40 Stone void ratio(%) N/A 40%
41 Is stone free of fines? N/A Yes
42 Is the stone wrapped in geotextile fabric? N/A yes__
_43 Has at least one infiltration port been provided? N/A J Yes
Volumes/ADrawdown_ _
44 Design volume of SCM(cu ft) —Y — I ' 100112 cf 16618 c f _
45 Time to drawdown(hours) 4 'T1.85 hrs
��- ..ri.�aw-rr_-air_--. _�.v-s• rr-aaawae - _ - Y
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the infiltration `„ t y4 ) ,,, IA evil
46 system(s): �y`„
1. Borings 11-17 average to find SHWT&Rate for Basin. {{ �--n 1~ __-.�
2 Borings 18-110 average to find SHWT&Rate for Trer I E F 14 . ;,;.;-
3. ECS did report to allow Infiltration Basin#1 to have 1 foot separation between
I bottom&SHWT. I OCT 13 202j i
B
Infiltration 1 2:34 PM 10/8/2020

LIMITED LIABILITY COMPANY ANNUAL REPORT ■
10/2017
NAME OF LIMITED LIABILITY COMPANY: Seamist Properties, LLC
Filing Office Use Only
SECRETARY OF STATE ID NUMBER: 0593182 STATE OF FORMATION: NC E-Filed Annual Report
0593182
REPORT FOR THE CALENDAR YEAR: 2020 CA202010611295
4/15/2020 02:45
SECTION A: REGISTERED AGENTS INFORMATION Changes
1. NAME OF REGISTERED AGENT: Dull, McKinley D
2.SIGNATURE OF THE NEW REGISTERED AGENT:
SIGNATURE CONSTITUTES CONSENT TO THE APPOINTMENT
3. REGISTERED AGENT OFFICE STREET ADDRESS&COUNTY 4.REGISTERED AGENT OFFICE MAILING ADDRESS
3807 Peachtree Ave.,Suite 200 3807 Peachtree Ave.,Suite 200
Wilmington, NC 28403-6725 New Hanover County Wilmington,NC 28403-6725
SECTION B: PRINCIPAL OFFICE INFORMATION
1. DESCRIPTION OF NATURE OF BUSINESS: Real Estate Investments
2. PRINCIPAL OFFICE PHONE NUMBER: [phone] 3.PRINCIPAL OFFICE EMAIL: Privacy Redaction
4. PRINCIPAL OFFICE STREET ADDRESS 5.PRINCIPAL OFFICE MAILING ADDRESS
3807 Peachtree Ave.,Suite 200 3807 Peachtree Ave.,Suite 200
Wilmington, NC 28403-6725 Wilmington, NC 28403-6725
6.Select one of the following if applicable. (Optional see instructions)
The company is a veteran-owned small business
The company is a service-disabled veteran-owned small business
SECTION C: COMPANY OFFICIALS(Enter additional company officials in Section E.)
NAME: McKinley D Dull NAME: NAME:
TITLE: Manager TITLE: TITLE:
ADDRESS: ADDRESS: ADDRESS:
3807 Peachtree Avenue,Suite 200
Wilmington, NC 28403
SECTION D:CERTIFICATION OF ANNUAL REPORT. Section D must be completed in its entirety by a person/business entity.
McKinley D Dull 4/15/2020
SIGNATURE DATE
Form must be signed by a Company Official listed under Section C of This form.
McKinley D Dull Manager
Print or Type Name of Company Official Print or Type Title of Company Official
This Annual Report has been filed electronically.
MAIL TO:Secretary of State, Business Registration Division,Post Office Box 29525,Raleigh,NC 27626-0525

10/12/2020 North Carolina Secretary of State Search Results
• File an Annual Report/Amend an Annual Report • Upload a PDF Filing • Order a Document Online •
Add Entity to My Email Notification List • View Filings • Print a Pre-Populated Annual Report form • Print
an Amended a Annual Report form
Limited Liability Company
Legal Name
Seamist Properties, LLC
Information
Sosld: 0593182
Status: Current-Active 0
Date Formed: 6/4/2001
Citizenship: Domestic
Annual Report Due Date: April 15th
Registered Agent: Dull, McKinley D
Addresses
Mailing Principal Office
3807 Peachtree Ave., Suite 200 3807 Peachtree Ave., Suite 200
Wilmington, NC 28403-6725 Wilmington, NC 28403-6725
Reg Office Reg Mailing
3807 Peachtree Ave., Suite 200 3807 Peachtree Ave., Suite 200
Wilmington, NC 28403-6725 Wilmington, NC 28403-6725
Company Officials
All LLCs are managed by their managers pursuant to N.C.O.S. 57D-3-20.
Manager
McKinley D Dull E •.,,,. _,R.
3807 Peachtree Avenue, Suite 200
Wilmington NC 28403 LL T 13 2020
BY
https://www.sosnc.gov/online servicesisearch/Business_liegistration_Results 1 1

frt."'
w LIMITED LIABILITY COMPANY ANNUAL REPORT
10/2017
NAME OF LIMITED LIABILITY COMPANY: Seamist Properties, LLC
Fling Office se Only
SECRETARY OF STATE ID NUMBER:
0593182 STATE OF FORMATION: NC E-Filed Annual Report
0593182
REPORT FOR THE CALENDAR YEAR: 2020 CA202010611295
4/15/2020 02:45
SECTION A:REGISTERED AGENT'S INFORMATION Changes
1.NAME OF REGISTERED AGENT: Dull, McKinley D
2.SIGNATURE OF THE NEW REGISTERED AGENT:
SIGNATURE CONSTITUTES CONSENT TO THE APPOINTMENT
3. REGISTERED AGENT OFFICE STREET ADDRESS&COUNTY 4.REGISTERED AGENT OFFICE MAILING ADDRESS
3807 Peachtree Ave.,Suite 200 3807 Peachtree Ave.,Suite 200
Wilmington,NC 28403-6725 New Hanover County Wilmington,NC 28403-6725
SECTION B: PRINCIPAL OFFICE INFORMATION
1. DESCRIPTION OF NATURE OF BUSINESS: Real Estate Investments
2.PRINCIPAL OFFICE PHONE NUMBER: [phone] 3.PRINCIPAL OFFICE EMAIL: Privacy Redaction
4.PRINCIPAL OFFICE STREET ADDRESS 5.PRINCIPAL OFFICE MAILING ADDRESS
3807 Peachtree Ave.,Suite 200 3807 Peachtree Ave.,Suite 200
Wilmington,NC 28403-6725 Wilmington,NC 28403-6725
6.Select one of the following if applicable.(Optional see instructions)
❑ The company is a veteran-owned small business
❑ The company is a service-disabled veteran-owned small business
SECTION C: COMPANY OFFICIALS(Enter additional company officials in Section E.)
NAME: McKinley D Dull NAME: NAME:
TITLE: Manager TITLE: TITLE:
i
ADDRESS: ADDRESS: ADDRESS: B 3 zz)
3807 Peachtree Avenue,Suite 200
Wilmington,NC 28403
SECTION D:CERTIFICATION OF ANNUAL REPORT. Section D must be completed in its entirety by a person/business entity.
McKinley D Dull 4/15/2020
SIGNATURE DATE
Form must be signed by a Company Official listed under Section C of This form.
McKinley D Dull Manager
Print or Type Name of Company Official Print or Type Title of Company Official
This Annual Report has been filed electronically.
MAIL TO:Secretary of State, Business Registration Division,Post Office Box 29525,Raleigh,NC 27626-0525

3 1�1I 3
9/51
1iHIl N10111111f11i1111111HU'�I1
2015010746
FOR REGISTRATION REGISTER OF DEEDS
NEW HANOVEERRCCOUNTTY'Nc
2015 APR 17 02 21 07 PIS
BK 5882 PG 450-456 FEE $26 00
KG REV STAMP�
IN OOUIiI 21151111746
Excise Tax $1,481 00 Recording Tune,Book and Page
Tax Lot No Parcel Identifier No A portion of R02400-001-001-000
Verified by County on the a day of 201_by
Mail after recording to Grantee at address shown below
This instrument was prepared by Womble Carlyle Sandridge&Rice,LLP(Hunter S Edwards)
**No title search performed and no title opinion given or implied by the preparer**
Brief Description For The Index
25 357 acres of real property located off of Highway 421 in New
Hanover County,North Carolina
NORTH CAROLINA SPECIAL WARRANTY DEED
THIS DEED made as of April 17,2015,by and between
GRANTOR.; GRANT ;,.;
INVISTA S.a r.I., SEAMIST PROPERTIES,LLC,
a Luxembourg societe responsabilite limitee, a North Carolina limited liability company
doing business in North Carolina as 1NVISTA
Sar1,LLC
Address Address
4123 East 37"'Street North 3807 Peachtree Avenue,Suite 200
Wichita,Kansas 67220 Wilmington,North Carolina 28403
Enter in -
appropriate block for each party name, address, and, if appropriate, character of
corporation or partnership "1z t, is ,
The designation Grantor and Grantee as used herein shall include said parties, their heirs, successo d44
assigns,and shall include singular,plural,masculine,feminine or neuter as required by context
RETURN TO: Douglas A. Fox
9

WITNESSETH, that Grantor, for a valuable consideration paid by Grantee, the receipt of which is
hereby acknowledged, has and by these presents does grant, bargain,sell and convey unto Grantee m fee
supple the property situated in New Hanover County,North Carolina and more particularly described on
Exhibit A attached hereto and incorporated herein by reference(the"Property")
The Property herein described is a portion of the property which was acquired by Grantor in instrument
recorded in Book 2485,Page 978
The Property herein conveyed does not include the primary residence of the Grantor, per NCGS 105-
317 2
TO HAVE AND TO HOLD the Property and all privileges and appurtenances thereto belonging to the
Grantee in fee simple,subject to the restrictions described on Exhibit B attached hereto and incorporated
herein by reference
And Grantor covenants with the Grantee, that Grantor has done nothing to impair such title as Grantor
received, and Grantor will warrant and defend the title against the lawful claims of all persons claiming
by,under or through Grantor,except for the exceptions hereinafter stated
This conveyance is expressly made subject to all matters set forth below and incorporated herein which
shall bind Grantee(and its successor in title)and run with the title to the Property
1 Lien(s)of ad valorem taxes for the year 2015 and thereafter which are not yet due and
payable,
2 Matters affecting title to the Property as shown on survey or from a current inspection of
the Property,
3 Zoning ordinances,building codes and other applicable laws,ordinances and
governmental regulations affecting the Property, and
4 All easements,encumbrances,covenants,restrictions,and conditions of record,and
rights-of-way of public and private streets and roads
[Signatures Begin on Following Page]
2

IN WITNESS WHEREOF,this deed has been duly executed as of the date first above written
GRANTOR;
INVISTA S.a rJ.,
a Luxembourg societe responsabihte limitee,doing
business in North Carolina as INVISTA S e r 1,LLC
By 1( f ,its
William Kmg,Authorized Si iatory Sic‘,t...k.sx.\
STATE OF NORTH CAROLINA
COUNTY OF NEW HANOVER
I certify that the following person personally appeared before me this day, acknowledging to me
that he voluntarily signed the foregoing document for the purpose stated therein and m the capacity
mdicated William King
Date April 17 ,2015
0, cy\e..._. ,
0�9ct Signature otaty
Notary Public = Lori A. Lewis
New Hanover County Notary's printed or typed name,Notary Public
4 �T`
(Official Seal) '�i,;'11rC,aRO`.��`�� My commission expires 09/01/2018
•Nttt3

ACCEPTED and duly executed by the Grantee as of the date first above written
GRANTEE:
SEAMIST PROPERTIES,LLC,
a North Carolina limited liability company
By
Nam McKinley Du l
Title Member/Manager
STATE OF NORTH CAROLINA
COUNTY OF NEW HANOVER
I certify that the following persons personally appeared before me this day,acknowledging to me
that they voluntarily signed the foregoing document for the purpose stated therein and in the capacity
indicated McKinley D. Dull
Date April 17 ,2015
y0.1 A LE "4s','4 cral ature o ataxy
Lori A. Lewis
Notary Public = Notary's printed or typed name,Notary Public
a New Hanover County
(Official Sealf: P My commission expires 09/01/2018
4

Exhibit"A"
BEING ALL of that 25.357 acre tract of land as shown on that plat entitled"Survey for INVISTA
S.A.R..L. Properties Lands on U.S.421 Part of R02400-001»001-000, Cape Fear Township, New
Hanover County,North Carolina"recorded in Plat Book 60 ,at Page L61 0 ,in the New Hanover
County Public Registry.
Further described as:
LEGAL DESCRIPTION OF PARCEL A,INVISTA S a.r.I.PROPERTY
Beginning at an existing iron rod located in the eastern right-of-way of U.S. Highway 421,said iron pipe
being located North 50°27'37" East 149.00' from NCGS Monument "FINA" N: 204,041.30' E:
2,307,567.82 NAD 83(2001),said iron pipe also being at southwest intersection of a point formed by the
eastern right-of-way of Highway 421 and a 65'wide access and utility easement as recorded in DB 5447,
Page 1139 in the New Hanover County Register of Deeds; running thence from said beginning point
North 57°11'51" East 500.12'along the southern line of the aforementioned 65' wide access and utility
easement to a newly set iron rod; thence South 32°47'47" East 1026.94 to a point; thence South
57°12'13"West 25.0' to a point;thence South 32°4747"East 50.0'to a point; thence North 57°12'13"
East 25.0' to a point; thence South 32°47'47" East 141.19' to a newly set iron rod; thence South
32°45'55"East 1011.38'to an existing iron pipe,said iron pipe being located in the northeast corner of
property now or formerly owned by BGM Properties,LLC as recorded in DB 5166,Page 2738 of the New
Hanover County Register of Deeds,thence South 57°12'531' West 500.12'along the northern property
line of the BGM Properties, LLC land to a newly set iron rod in the eastern right-of-way of Highway 421;
thence running along the eastern right-of-way of the Highway North 32°45'55"West 1011.38'feet to an
existing concrete monument in the eastern right-of-way of the Highway;thence continuing along the
right-of-way of the Highway North 32°47'47"West 1197 81'to the point and place of beginning.
The subject property is located in New Hanover County North Carolina and contains 25.357 acres as
shown on a survey prepared by Paramounte Engineering, Inc. The property is subject to an existing 60'
wide Permanent Easement as shown in DB 5351 Page 302 of the New Hanover County Register of Deeds
and a 30'wide CP&L Easement (centered on the eastern right-of-way of U.S. Highway 421) as recorded
in DB 1142 Page 56 of the New Hanover County Registry.

EXHIBIT B
to North Carolina Special Warranty Deed
Restrictions
1. The Property shall never be used for residential purposes and this restrictive covenant shall run
with the title to the Property and be binding upon the Property and upon Grantee,its successors
and assigns and inure to the benefit of Grantor,its successors and assigns.
2. No groundwater from the Property shall be used for consumption and this restrictive covenant
shall run with the title to the Property and be binding upon the Property and upon Grantee, its
successors and assigns and inure to the benefit of Grantor,its successors and assigns.
3. No more than thirty-five thousand(35,000)gallons of groundwater per day shall ever be pumped
for removal for use by occupiers of the Property and this restrictive covenant shall run with the
title to the Properly and be binding upon the Property and upon Grantee, its successors and
assigns and inure to the benefit of Grantor,its successors and assigns.
Grantor shall have the right to prohibit the installation of any pumping equipment on the Property
(the"Pumping Equipment")if the Pumping Equipment would allow more than 35,000 gallons of
groundwater per day to be removed from the Property and subsequent modification of the
Pumping Equipment that would increase its pumping capacity is prohibited unless consented to
by Grantor in writing prior to any such modification. Upon reasonable advance notice to
Grantee,Grantor shall have the right to enter the Property from time to time to ensure compliance
with this restrictive covenant; provided that such inspection and audit shall not unreasonably
interfere with Grantee's operations on the Property,and Grantor's representatives check in at the
time of such inspection or audit with the Grantee's on-site manager(s) and comply with all of
Grantee's reasonable safety requirements.
4. Should public water service ever become available to the Property,Grantee shaft tie the Property
into and connect the Property to such public water service and this obligation shall run with the
title to the Property and be binding upon the Property and upon Grantee, its successors and
assigns and inure to the benefit of Grantor,its successors and assigns

11 ii 'i
I j
,r "4. s
n
Aiusllo
TAMMY THEUSCH BEASLEY
REGISTER OF DEEDS, NEW HANOVER
216 NORTH SECOND STREET
WILMINGTON, NC 28401
Filed For Registration: 04/17/2015 02:21:07 PM
Book: RE 5882 Page: 450-458
Document No.: 2015010746
7 PGS $28.00
NC REAL ESTATE EXCISE TAX: $1,481.00
Recorder: CRESWELL,ANDREA
State of North Carolina,County of New Hanover
PLEASE RETAIN YELLOW TRAILER PAGE WITH ORIGINAL DOCUMENT.
* 2015010746 *
2015010746

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STORMWATER SYSTEM & EROSION CONTROL CALCULATIONS
WILMINGTON TRADE CENTER
4104 US Hwy. 421 North
Wilmington, North Carolina
rereu
For
3 2023
Seamist Properties, LLC BY:
3807 Peachtree Avenue, Suite 200
Wilmington, NC 28403
[phone]
1 1u1 III,,
SEA�Lg
**.A, L,.'
SON GAP°,,.
,ry,,,,,,,111111111t 111tttttttt
October 2020
Prepared by:
NORRIS &TUNSTALL CONSULTING ENGINEERS, P.C.
2602 Iron Gate Drive, Suite 102
Wilmington, North Carolina 28412
[phone]
[phone] (Fax)
License#C-3641
N&T Project No. 19131

Date Design
NORRIS 8,7._ TUNSTALL Wilmington, NC Sheet
I 0-1-20 e_.„ —CONSULTING ENGINEERS P.C.— Brunswick County, NC
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CONSULTING ENGINEERS P.C.— Brunswick County, NC
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"Trab l.6.14.: sly./ SeeS.mxe.At Rum
I
Calculate Skimmer Size
Basin Volume in Cubic Feet 55,758 Cu.Ft Skimmer Size 4.0 Inch
Days to Drain* 3 Days Orifice Radius 1.9 Inch[esi
Orifice Diameter 3.8 Inch[esj
l'In NC assume 3 days to drain
Estimate Volume of Basin Length Width
Top of water surface in feet Feet VOLUME 0 Cu.Ft.
Bottom dimensions in feet Feet
Depth in feet Feet

Date Dey NORRIS & TUN STALL Wilmington, NC 7...::>-"----//
CONSULTING ENGINEERS P.C.--- Brunswick County, NC
Of
Check Jo For Job No.
EC, 604-ICS WIPthl 1129 4A"fra-ek /1/3 II
I 1 ! 1 l' il 1 IIIIII , I
11C- S .,C-0,1‘.0( 4C64 Oel-2 LI-e- i$ 11'1- 44
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Channel Report
Hydraflow Express Extension for Autodesk®AutoCAD®Civil 3D®by Autodesk,Inc. Thursday,Oct 8 2020
Swale 1 (5:1)
Triangular Highlighted
Side Slopes (z:1) = 5.00, 5.00 Depth (ft) = 0.27
Total Depth (ft) = 1.50 Q (cfs) = 0.660
Area (sqft) = 0.36
Invert Elev (ft) = 21.00 Velocity (ft/s) = 1.81
Slope (%) = 3.00 Wetted Perim (ft) = 2.75
N-Value = 0.035 Crit Depth, Yc (ft) = 0.26
Top Width (ft) = 2.70
Calculations EGL (ft) = 0.32
Compute by: Known Q
Known Q (cfs) = 0.66
a
Elev (ft) Depth (ft)
Section
23.00 2.00
22.50 =- - - 1.50
22.00 1.00
i
21.50 0.50
'7.7 i
21.00
20.50 I I I
-0.50
0 2 4 6 8 10 12 14 16 18 20
Reach (ft)

Channel Report
Hydraflow Express Extension for Autodesk®AutoCAD®Civil 3D®by Autodesk,Inc. Thursday,Oct 8 2020
Swale 1 (5:1)
Triangular Highlighted
Side Slopes (z:1) = 5.00, 5.00 Depth (ft) = 0.28
Total Depth (ft) = 1.50 Q (cfs) = 0.760
Area (sqft) = 0.39
Invert Eiev (ft) = 21.00 Velocity (ft/s) = 1.94
Slope (%) = 3.00 Wetted Perim (ft) = 2.86
N-Value = 0.035 Cult Depth, Yc (ft) = 0.28
Top Width (ft) = 2.80
Calculations EGL (ft) = 0.34
Compute by: Known Q
Known Q (cfs) = 0.76Qtr
Elev (ft) Depth ft( )
Section
23.00 2.00
22.50 --- 1.50
7---
22.00 0 1.00
21.50 i 0.50
21.00 I 0.00
I.
20.50 I 1 I ( E
-0.50
0 2 4 6 8 10 12 14 16 18 20
Reach (ft)

Channel Report
Hydraflow Express Extension for Autodesk®AutoCAD®Civil 3D®by Autodesk,Inc. Thursday,Oct 8 2020
Swale 1 (5:1)
Triangular Highlighted
Side Slopes (z:1) = 5.00, 5.00 Depth (ft) = 0.31
Total Depth (ft) = 1.50 Q (cfs) = 1.000
Area (sqft) = 0.48
Invert Elev (ft) = 21.00 Velocity (ft/s) = 2.08
Slope (%) = 3.00 Wetted Perim (ft) = 3.16
N-Value = 0.035 Crit Depth, Yc (ft) = 0.31
Top Width (ft) = 3.10
Calculations EGL (ft) = 0.38
Compute by: Known Q
Known Q (cfs) = 1.00 -- 010
Elev (ft) Depth ft( )
Section
23.00 2.00
22.50 --Q- 1.50
7
22.00 1.00
\ ,-///
21.50 0.50
pp
o.
l 1
21.00 i I I i 0.00
20.50 1
-0.50
0 2 4 6 8 10 12 14 16 18 20
Reach (ft)

•
Infiltration Basins I % 2
CONCRETE,CURB IMPERVIOUS
TOTAL(SF)
4,
TOTAL AREA(SF) ASPHALT(SF) &GUTTER(SF) SIDEWALK(SF) BUILDING(SF)
OFFSITE(SF) %IMPERVIOUS
DA1 11,100 6,661 809 0 0 0 7,470 67
80
DA2 64,486 12,251 8,841 0 30,587 4,852 51,679
DA6 91659 27400 15072 0 47543 0 90015 98
DAB 80070 22246 14739 0 42859 0 79844 100
DA10 73640 23272 12796 0 35884 0 71952 98
DA12 2850 1382 202 93 0 0 1677 59
DA13 2670 1572 174 32 0 0 1778 67
DA15 3268 1360 210 120 0 0 1690 52
OA16 3093 1590 184 41 0 0 1815 59
DA18 73160 23330 12206 0 35043 0 70579 96
DA20 80000 22238 14747 0 42850 0 79835 100
DA22 78079 21693 14378 0 41858 0 77929 100
DA24 77613 25524 12889 0 36933 0 75346 97
DA26 3290 1350 200 108 0 0 1658 50
DA27 1949 799 118 65 0 0 982 50
DA29 4515 1350 200 182 0 0 1732 38
DA30 2676 802 119 121 0 0 1042 39
DA32 75823 25532 12377 0 34616 0 72525 96
DA34 78082 21700 14400 0 41998 0 78098 100
DA36 67861 23513 10620 0 33609 0 67742 100
DA41 84095 0 0 0 0 0 0 0
DA42 29274 0 0 0 0 0 0 0
TOTAL(SF) 989,253 265,565 145,281 762 423,780 4,852 835,388 84.4
TOTAL(AC) 22.71 6.10 3.34 0.02 9.73 0.11 19.178
**On the Plans the Basin is split Into two basins,Basin 1 and 2.They function as one Basin.
80 SkS j ' Z (As No c( v,if
leo s) r ,,t Amp Ore 19,m14.1 ifiel
A., 0 qe

Date Design NORRIS & TUNSTALL Wilmington, NC Sheet
—CONSULTING ENGINEERS P.C.— Brunswick County, NC
Of
Check Job 11C-/ For Job No.
a1( atiC.S Itr,1444'qiil &Kill tdetilA —r-r4tf.k CeAt.4-e,f I I
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Date Design NORRIS & TUNSTALL Wilmington, NC Sheet -
CONSULTING ENGINEERS P.C.— Brunswick County, NC
Of
Check Job For Job No.
SC.-- CCA-kC.S , likAffv;- —6:41462_ ce,t.1-, lett7
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0 0
Predeveloped Runoff 1140 Busi ess PArk
Infiltration Basin 1 Ph se 5
0 A
Infiltration Basin 1
Predeveloped Runoff to
Property East of Site Civrre q.s
within Infiltration Basin ,f.�,,,, e «,c ('See. ,GCS
1
gydroleo(05k 646g.4 :on;To
P11ot...) Fiv r c e4 Sc ►c4,A n
t CA.SeCI = 1 Sin A/.
Qro i Oar - COC FS
IQs0 v Z 17.* "cps Fru = f eiS1 '
(Subca) Reach 'on. Drainage Diagram for 19131 Phase 5 1140 Basin OCT 2020
Prepared by Norris&Tunstall Consulting Engineers 10/9/20
HydroCAD®7.10 sin 000479 0 2005 HydroCAD Software Soiutions LLC

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 2
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1 Runoff Area=22.710 ac Runoff Depth=0.00"
Tc=10.0 min CN=36 Runoff=0.00 cfs 0.000 af
Subcatchment 2S: Predeveloped Runoff to Property East of SSunoff Area=3.810 ac Runoff Depth=0.00"
Tc=10.0 min CN=36 Runoff=0.00 cfs 0.000 af
Subcatchment 3S: 1140 Business PArk Phase 5 Runoff Area=22.710 ac Runoff Depth>0.58"
Tc=10.0 min CN=89 Runoff=14.28 cfs 1.099 af
Pond 3P: Infiltration Basin 1 Peak Elev=10.60' Storage=2,834 cf Inflow=14.28 cfs 1.099 af
Discarded=10.40 cfs 1.098 af Primary=0.00 cfs 0.000 af Outflow=10.40 cfs 1.098 af
Total Runoff Area = 49.230 ac Runoff Volume= 1.099 af Average Runoff Depth =0.27"

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 3
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af, Depth= 0.00"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Area (ac) CN Description
22.710 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
®Runoff
Runoff=0.00 cfs
Type III 24-hr 1.5 inch Storm
Rainfall=1.50"
Runoff Area=22:.710 ac
Runoff Volume=0.000 af
;Runoff Depth=0.00"
Tc=10.0 min
CN=36
5 6 7 8 9 10 • 11 • 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 4
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af, Depth= 0.00"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Hydrograph
0 Runoff
Runoff=0.00 cfs
Type III 24-hr 1.5 inch Storm
Rainfall=1.50"
Runoff Area=3.810'ac
Runoff Volume=0.000 af
Runoff Depth=0.00"
Tc=10.0 min
!CN=36
l a.ao as s� ;
0�{ �r %>; 7iir�//f/ _ ///f� /(< �"FT
5 6 7 8• 9 10 'ii 12. 13 14 15 16 .17. 18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 5
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 14.28 cfs @ 12.15 hrs, Volume= 1.099 af, Depth> 0.58"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Area (ac) CN Description
19.178 98 Bldgs, Asphalt, Concrete
3.532 39 >75% Grass cover, Good, HSG A
22.710 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
15: ErEa 1 r Runoff
'
14- R�ulnoff fs
_14.28
.
Type III.24-hr-1.5 inch St rm
12.
Rainfall=1:50"-
11
10.
Runoff A rrea=22:710:ac..
:
s 'Runoff Volume-T.-1.099 af
t 8 ;Runoff Depth>0 58"
s _
10.0
s' :
CN=89n
� . i.
4 ... ,
3
2 1L -_
p ?i0lriirrrrirrirrr rirer. ��- � /4 f/97
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstail Consulting Engineers Page 6
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
Inflow Area = 22.710 ac, Inflow Depth > 0.58" for 1.5 inch Storm event
Inflow = 14.28 cfs @ 12.15 hrs, Volume= 1.099 af
Outflow = 10.40 cfs @ 12.27 hrs, Volume= 1.098 af, Atten= 27%, Lag= 7.0 min
Discarded = 10.40 cfs @ 12.27 hrs, Volume= 1.098 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 10.60'@ 12.27 hrs Surf.Area= 29,956 sf Storage= 2,834 cf
Plug-Flow detention time=2.6 min calculated for 1.094 af(100% of inflow)
Center-of-Mass det. time=2.2 min ( 811.1 - 808.9)
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismatic)Listed below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store �A 1y�35 970 /$o5R
(feet) (sq-ft) (cubic-feet) (cubic-feet) J
10.50 28,925 0 0 r 7o1.4M a )e4.3,51. I(0 71$de
15.00 77,114 238,588 238,588 �J
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Qiscarded OutFlow Max=10.40 cfs @ 12.27 hrs HW=10.60' (Free Discharge)
1=Exfiltration (Exfiltration Controls 10.40 cfs)
rimary OutFlow Max=0.00 cfs @ 5.00 hrs HW=10.50' (Free Discharge)
2=Broad-Crested Rectangular Weir(Controls 0.00 cfs)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 7
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
Hydrograph
*1 Inflow
1 Outflow
Inflow-.i4 _rea 22.7'L ICI DiscardedO.ac Primary
14:
In# —ow 14 28 "cfs-
13= �-
.
12: t --
. L70-40da ',
®l.�tfiOW
40 cfs
_ --" .. ; o.aofcrs - -
„ Discarded=10.40--cfs
PeiMar00.00 cfs
", Peak Elev-10.60'
. -Storage 2,834 cf
I . .... .... .. . .
_...
o.on" tor
y/�//�/�/�//r/y/f��f 1
0 raft.f*d'i::1 "YY�f�+'€� 4V4;.(i.74d.71;›—el;e#M.'',1`.f f;.: i✓�J', _. P S�d'P;^r�
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 8
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1 S: Predeveloped Runoff Infiltration Basin 1 Runoff Area=22.710 ac Runoff Depth>0.03"
Tc=10.0 min CN=36 Runoff=0.13 cfs 0.056 af
Subcatchment 2S: Predeveloped Runoff to Property East of Runoff Area=3.810 ac Runoff Depth>0.03"
Tc=10.0 min CN=36 Runoff=0.02 cfs 0.009 af
Subcatament 3S: 1140 Business PArk Phase 5 Runoff Area=22.710 ac Runoff Depth>3.10"
Tc=10.0 min CN=89 Runoff=74.09 cfs 5.875 af
Pond 3P: Infiltration Basin 1 Peak Elev=12.45' Storage=76,599 cf Inflow=74.09 cfs 5.875 af
Discarded=17.28 cfs 5.872 af Primary=0.00 cfs 0.000 af Outflow=17.28 cfs 5.872 af
Total Runoff Area=49.230 ac Runoff Volume= 5.941 af Average Runoff Depth = 1.45"

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 9
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Runoff = 0.13 cfs @ 15.69 hrs, Volume= 0.056 af, Depth> 0.03"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 2-yr Rainfall=4.50"
Area (ac) CN Description
22.710 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
7 :
©Runoff
0.13= • /%�lh'►� i.
Runoff=0'413_cfs : . „..
0.12_ ;
.. Type III .24-h r 2-y r ; _ :
0.11 , i , ,
0.1 Rainfa11=4.50 :.
0.09 Runoff Area=,22.710 ac ,
0.06�
.- Runoff Volume=0..056 at iFliPi
� 0.07_
LL
R :moff Depth>0.03
0.06
i
0.05- -. . Tc=10.0 thin -
0.04 CN=36
...
0.02-. /
0.01. ; �-
0 t'i�{..///////////!/4/ /, f/JfJ�. .. /
5 6 7 8 9 10 11 12 13 ir'14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 10
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Runoff = 0.02 cfs @ 15.69 hrs, Volume= 0.009 af, Depth> 0.03"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 2-yr Rainfall=4.50"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin I
Hydrograph
0.024 •
; '
0.023 ®Runoff
T ..,. .. ... O -... .. ....
0.022 cfs .
0.021 Runoff=0:02.:cfs..; ;:'�
0.0
0.0219 .
Type.-I11.24-hr 2 . r , . . _
0.017 OInfa11= 50" .. . .
00..0015 =. !16 Runoff Area-3.8' 0....ac
0.01
0.013 - -Runoff-Volume=0.009 of ,...-
0.012 1 '. . .._ 1_ _. .
LL 0.011 Runoff Dep
th>0.0 3" _ -
0.01
0.000 To=10.0 min . _ ;
0.008
0.007 - I..
CN=36 i
0.006 ,
0.005
0.004
0.003 '
0.002 I ..
0.0001 t;'////// ./.7 ./!///._<4:7 /
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 11
HydroCADe 7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 74.09 cfs @ 12.14 hrs, Volume= 5.875 af, Depth> 3.10"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 2-yr Rainfall=4.50"
Area (ac) CN Description
19.178 98 Bldgs, Asphalt, Concrete
3.532 39 >75% Grass cover, Good, HSG A
22.710 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
_. CI Runoff
75 _
70 unoff=7409-cfs
65 •
Type_111 24-hr 2-y.r
Rainfall=4•.50"• ..
55
50- I ; I Runoff Area=22:710 ac e '
1
0 40= � . . . . �. � af
unoff.Volum 5.:8751 '�
LL 35:
Runoff Depth>3.1;0
.
0. 100 min
25-
20 � CW=89
104 . ..,
sYs Ts�—r s —oT ,�'-�s��s s�—V�'•r�--T�o e-I'�r—�s—s•rsy a sTs s
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 12
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
Inflow Area = 22.710 ac, Inflow Depth > 3.10" for 2-yr event
Inflow = 74.09 cfs @ 12.14 hrs, Volume= 5.875 af
Outflow = 17.28 cfs @ 12.59 hrs, Volume= 5.872 af, Atten= 77%, Lag= 26.8 min
Discarded = 17.28 cfs @ 12.59 hrs, Volume= 5.872 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 12.45'@ 12.59 hrs Surf.Area=49,771 sf Storage= 76,599 cf
Plug-Flow detention time=32.8 min calculated for 5.872 af(100% of inflow)
Center-of-Mass det. time=32.6 min ( 802.8 -770.3)
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismatic Jsted below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Discarded OutFlow Max=17.28 cfs @ 12.59 hrs HW=12.45' (Free Discharge)
L1=Exfiltration (Exfiltration Controls 17.28 cfs)
Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=10.50' (Free Discharge)
L2=Broad-Crested Rectangular Weir(Controls 0.00 cfs)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 13
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin I
Hydrograph
•
L'_�Inflow
'7: , - i , _ _
® -Outflow
.
t
Inflow Area=22:71 0 ac r Discarded
80= 0 Primary
754 "._ I _
nflow-74 09 cis
70` _
65- O_ufflow=17.28 cfs
i a e
D sc rd d=17.28 cfs
55=
50- i.
� P r fYlarY 90 C..S
30 40= • '
u_ 35- - - - =- - Storage 76,599 ;cf
30- r 1. i
25 1728 cts
1728ch
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 14
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1 Runoff Area=22.710 ac Runoff Depth>0.48"
Tc=10.0 min CN=36 Runoff=5.34 cfs 0.913 af
Subcatchment 2S: Predeveloped Runoff to Property East of SSunoffArea=3.810 ac Runoff Depth>0.48"
Tc=10.0 min CN=36 Runoff=0.90 cfs 0.153 af
Subcatchment 3S: 140 Business PArk Phase 5 Runoff Area=22.710 ac Runoff Depth>5.44"
Tc=10.0 min CN=89 Runoff=125.87 cfs 10.288 af
Pond 3P: Infiltration Basin 1 Peak Elev=13.85' Storage=157,281 cf Inflow=125.87 cfs 10.288 af
Discarded=22.52 cfs 10.282 af Primary=0.00 cfs 0.000 af Outflow=22.52 cfs 10.282 af
Total Runoff Area =49.230 ac Runoff Volume= 11.354 af Average Runoff Depth = 2.77"

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 15
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 1S: Predeveloped Runoff Infiltration Basin I
Runoff = 5.34 cfs @ 12.39 hrs, Volume= 0.913 af, Depth> 0.48"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 10-yr Rainfall=7.05"
Area (ac) CN Description
22.710 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin
Hydrograph
'
Runoff I 5.34!fs
Runoff=5.34 cfs
5-
Type III 24-hr106yr
- • Rainfalliz7;05"
4-
RUnoff Aiva*22.710 ac
I 3-
:Runoff Volume=0.913:af
o Runoff Depth>0.48"
-
2-
, TcF10:.0 rnin
; CN=36
1 ----44f4fezez27,
5 6 7 8 9 10 11 12 113 14 1'5 16 17 118 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 16
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Runoff = 0.90 cfs @ 12.39 hrs, Volume= 0.153 af, Depth> 0.48"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 10-yr Rainfall=7.05"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Hydrograph
1
0 Runoff
0.90 cfs
Runoff=0.00 cfs
1 Type:III 24-hr 10-yr
Rainfall=7.05"
Runpff Area=3.810 ;ac
,S Runoff.Volume=0.,153 of
Runoff Depth>0.48"
Tc=10L 0 min
CN=36
0 7//./<, JJJJJJ�J�/J/�/f/ff
5 6 7 S • • •9 • 10• • •11 12 13. . . .14. . • •15. . . .16, . . *17. • . .18" . ,1g, • . .20
Time (hours)

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 17
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 125.87 cfs @ 12.14 hrs, Volume= 10.288 af, Depth> 5.44"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 10-yr Rainfall=7.05"
Area (ac) CN Description
19.178 98 Bldgs, Asphalt, Concrete
3.532 39 >75% Grass cover, Good, HSG A
22.710 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
140
.
,. , ...._ . ..... ©Runoff
131 112517 cr.I r
120 Runoff=`12587 cfs
110 Type III 24-hr 10-yr
10o Rainfall=7.05"
80
Runoff Area:22.710
70
' •Runoff Volume=l..0288 -af...
Runoff Depth;>5:44"
IL 60
50 Tc=10.0 min
40 CN=89. ..
30
20 •
10 •dic�` • —• Jr
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 18
HydroCADO 7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
[82] Warning: Early inflow requires earlier time span
Inflow Area = 22.710 ac, Inflow Depth > 5.44" for 10-yr event
Inflow = 125.87 cfs @ 12.14 hrs, Volume= 10.288 af
Outflow = 22.52 cfs @ 12.65 hrs, Volume= 10.282 af, Atten= 82%, Lag= 30.8 min
Discarded = 22.52 cfs @ 12.65 hrs, Volume= 10.282 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 13.85'@ 12.65 hrs Surf.Area=64,847 sf Storage= 157,281 cf
Plug-Flow detention time=58.8 min calculated for 10.247 af(100% of inflow)
Center-of-Mass det. time=58.2 min ( 816.2 -758.0 )
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismaticjisted below(Recaic)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
iscarded OutFlow Max=22.52 cfs @ 12.65 hrs HW=13.85' (Free Discharge)
=Exfiltration (Exfiltration Controls 22.52 cfs)
Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=10.50' (Free Discharge)
L2=Broad-Crested Rectangular Weir(Controls 0.00 cfs)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 19
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
Hydrograph
--
Inflow, OutW
_ r de iInflowArea210 ac Pn140_ 0nary
:
Inflow=125.87 cfs
120..
_ _ . . a- - Outflow=22:52 cfs
110:"
100== , Discarded=22.52 Cfs
so ' Plr 00
- - —ima 0, cfs
80_"`
Peak Elev=73:85'
LL 60 Stora a=157 281'cf
50
0 �.e zGI fs
-
.. 22-52 cfa . � ..
77.
f
o.00 crs f
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 20
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1 Runoff Area=22.710 ac Runoff Depth>0.77"
Tc=10.0 min CN=36 Runoff=10.30 cfs 1.452 of
Subcatchment 2S: Predeveloped Runoff to Property East of Runoff Area=3.810 ac Runoff Depth>0.77"
Tc=10.0 min CN=36 Runoff=1.73 cfs 0.244 af
Subcatchment 3S: 1140 Business PArk Phase 5 Runoff Area=22.710 ac Runoff Depth>6.32"
Tc=10.0 min CN=89 Runof=145.18 cfs 11.963 of
Pond 3P: Infiltration Basin 1 Peak Elev=14.34' Storage=189,848 cf Inflow=145.18 cfs 11.963 af
Discarded=24.31 cfs 11.956 af Primary=0.00 cfs 0.000 af Outflow=24.31 cfs 11.956 af
Total Runoff Area =49.230 ac Runoff Volume= 13.658 af Average Runoff Depth = 3.33"

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 21
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment IS: Predeveloped Runoff Infiltration Basin 1
Runoff = 10.30 cfs @ 12.27 hrs, Volume= 1.452 af, Depth> 0.77"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 25-yr Rainfall=8.01"
Area (ac) CN Description
22.710 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
11_ 9 Runoff
10.30 cfs
10 h; A 'Runoff;10 30 cfs
Type:I I 124-h r 25=y r
8 Rainfall=8.01"
7= " - Runoff Area=22.710 ac
Runoff V(*lit a=1 452 of
0
Runoff Depth>0.77"
LL 5_
Tc=10:0
4-
3 CI@:36
5 6 7 8 9 10 11 12 13 14 15. 16 17. 18. 119• . . 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 22
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Runoff = 1.73 cfs @ 12.27 hrs, Volume= 0.244 af, Depth> 0.77"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 25-yr Rainfall=8.01"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Hydrograph
U Runoff
Runoff=1.13 cfs
Type;III 24-hr 25 yr
Rainfall=8.01"
Runoff Area=3.$10 ac
1- Runoff Volume=0:244r of
LL Runoff Depth>0.77"
Tc=10:0 min
CN=36
5 6 7 8 9 10 11 12 13 14 15 '16 1 18I 19 • 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 23
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 145.18 cfs @ 12.14 hrs, Volume= 11.963 af, Depth> 6.32"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 25-yr Rainfall=8.01"
Area (ac) CN Description
19.178 98 Bldgs, Asphalt, Concrete
3.532 39 >75% Grass cover, Good, HSG A
22.710 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
•
. . :..... ..
160- Runoff
:
1504 145.18 cis •
140: .:. un ff=;14518 cfs
130_ , Type III 24-hr 25=yr
120_-'
no.; Rainfall=8:04-"
Runoff.Area=22:710-:ac
90:
Runoff V.olumer411 963;-af
80= ay
LL 70- Runoff Depth>6;32"
,_ ]
60-
Tc=10:0 min
f
�._
30=
20= �
10=
0 n i er o n �
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 24
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
[82] Warning: Early inflow requires earlier time span
Inflow Area = 22.710 ac, Inflow Depth > 6.32" for 25-yr event
Inflow = 145.18 cfs @ 12.14 hrs, Volume= 11.963 of
Outflow = 24.31 cfs @ 12.67 hrs, Volume= 11.956 af, Atten= 83%, Lag= 31.9 min
Discarded = 24.31 cfs @ 12.67 hrs, Volume= 11.956 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 14.34'@ 12.67 hrs Surf.Area= 70,019 sf Storage= 189,848 cf
Plug-Flow detention time=67.6 min calculated for 11.955 af(100% of inflow)
Center-of-Mass det. time=67.3 min (822.4 -755.1 )
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismatic)Listed below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feetL_ (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Qscarded OutFlow Max=24.31 cfs @ 12.67 hrs HW=14.34' (Free Discharge)
1=Exfiltration (Exfiltration Controls 24.31 cfs)
Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=10.50' (Free Discharge)
L2=Broad-Crested Rectangular Weir(Controls 0.00 cfs)

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 25
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
Hydrograph
�J
... . , if;Inflow
1_ 78
: Outflow
1so_
inflowArea=22:710 ad oP aryed
1
:: In'flow-145' 8 cfs
140 ,
130 ' ;. . ... _ r Outflow=24 31 cfs ._..
120
-
110,'
. Dlscarded-;24.3; cfs
100_
:
_ . rimary 0.00 cfs
, ,
Peak f lev 14.34'
80 ,
_
it 70_ . _ . - Storage=1.89,848cf
60=
50
® 'r`r vi
30
r,.
•-' : ///sty -
rriiirrirr f g
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19' 20
Time (hours)

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 26
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Predeveloped Runoff infiltration Basin 1 Runoff Area=22.710 ac Runoff Depth>1.12"
Tc=10.0 min CN=36 Runoff=18.60 cfs 2.116 af
Subcatchment 2S: Predeveloped Runoff to Property East of$funoff Area=3.810 ac Runoff Depth>1.12"
Tc=10.0 min CN=36 Runoff=3.12 cfs 0.355 af
Subcatchment 3S: 1140 Business PArk Phase 5 Runoff Area=22.710 ac Runoff Depth>7.24"
Tc=10.0 min CN=89 Runoff=165.20 cfs 13.709 af
Pond 3P: Infiltration Basin 1 Peak Elev=14.57' Storage=206,718 cf Inflow=165.20 cfs 13.709 af
Discarded=25.19 cfs 12.991 af Primary=27.95 cfs 0.710 af Outflow=53.15 cfs 13.701 af
Total Runoff Area =49.230 ac Runoff Volume= 16.180 af Average Runoff Depth = 3.94"

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 27
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Runoff = 18.60 cfs @ 12.20 hrs, Volume= 2.116 af, Depth> 1.12"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 50-yr Rainfall=9.01"
Area (ac) CN Description
22.710 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
20 El Runoff
19' l 18 6(cfs
18_ ... _ . _. .. Runoff' 1.8.60 cfs _.
;6 Type' III-24-hr 50=yr
15= ;
151 =9.01'
a Rainfall
Runoff Area-22.710 ac
11 . . _ _ .Runoff.Volume=2:1l-1.6.'a.f...
,o=
LL 0. . .Rt noff Depth>1.12" -
8
7-E Te=10'.0 niin
6-
CN='36 ..
4
I , -777 tz-7,
ti . , I ,2' P
" . , i _
0.1,417.-,/.-<_<-7, /-1,-.<, . . . , . . . . , . . .,:".r.A': . , . : : . . , ' , . . '. . . , , . . : . , : . -: . , (
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 28
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Runoff = 3.12 cfs @ 12.20 hrs, Volume= 0.355 af, Depths 1.12"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 50-yr Rainfall=9.01"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Hydrograph
©Runoff
1 9.12 cfs 1
3- i u n off=3.12 cfs
Type;III 24-hr 501r
Rainfall=9.01"
Runoff-Area=3..8-10-ac-
w 2-, I I
Runoff:Volume=0.355:of
fL
Runoff Depfih>1.12"
•
Tc=10 0 min
1- g '�/ CN 36
5 6 7 8 9 10 11 12 '13 '14' '15. •16. .17. '18• • . .19' .20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 29
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 165.20 cfs @ 12.14 hrs, Volume= 13.709 af, Depth> 7.24"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 50-yr Rainfall=9.01"
Area (ac) CN Description
19.178 98 Bldgs, Asphalt, Concrete
3.532 39 >75% Grass cover, Good, HSG A
22.710 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
180= :. ®Runoff
170=" 6520 ds
i
,60:
. .unoff:;165 1;20 cfs ..
150' Type IFI 24-h;r 50�yr
130t
RainfailL-9 01"
120 s
110-
Runoff Area=22-.710-ac
Runoff yol lme=13 709'.af
o .
Runoff Depth;>7:24"
�- 80q
70' '
Tc.=10.0. min _.
60
CN=89
50=
40=
6 7 8 9 10 ,1 12 • 13 14 75 18 17 • • 18 • • 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type 111 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 30
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
[82] Warning: Early inflow requires earlier time span
Inflow Area = 22.710 ac, Inflow Depth > 7.24" for 50-yr event
Inflow = 165.20 cfs @ 12.14 hrs, Volume= 13.709 af
Outflow = 53.15 cfs @ 12.50 hrs, Volume= 13.701 af, Atten=68%, Lag= 21.6 min
Discarded = 25.19 cfs @ 12.50 hrs, Volume= 12.991 af
Primary = 27.95 cfs @ 12.50 hrs, Volume= 0.710 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 14.57'@ 12.50 hrs Surf.Area= 72,553 sf Storage= 206,718 cf
Plug-Flow detention time=66.9 min calculated for 13.655 af(100% of inflow)
Center-of-Mass det. time=66.3 min ( 819.0- 752.7)
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismatic Jsted below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Qiscarded OutFlow Max=25.19 cfs @ 12.50 hrs HW=14.57' (Free Discharge)
1=Exfiltration (Exfiltration Controls 25.19 cfs)
rimary OutFlow Max=27.73 cfs @ 12.50 hrs HW=14.57' (Free Discharge)
2=Broad-Crested Rectangular Weir(Weir Controls 27.73 cfs @ 1.2 fps)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris &Tunstall Consulting Engineers Page 31
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
Hydrograph
/ , ;
---crsI l._ 1 .. . _ . _. .. -i inflow
D sccard
.1 D
180i
:.Inf Ow /olrea=22 7.10.. ac Primaryed
Inflow 165;20 cfs
160-
150= . Outflow=53:1 5 cfs. .;
140
130- . '
Discarded=25:1 9-cfs
110 ;. _ .. . .. .._p.rlmary=2795 cfs...
Peak Ele
100 v=14:57'
,
3 90
80 -53.,5�s Storage=206,718 cf..
so _
50 •
1 Ea _ 1 ';• I- r� r.
ELM
10 i --- '��''''' - -
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 32
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 15: Predeveloped Runoff Infiltration Basin 1 Runoff Area=22.710 ac Runoff Depth>1.51"
Tc=10.0 min CN=36 Runoff=28.53 cfs 2.863 af
Subcatchment 2S: Predeveloped Runoff to Property East of SiunoffArea=3.810 ac Runoff Depth>1.51"
Tc=10.0 min CN=36 Runoff=4.79 cfs 0.480 af
Subcatchment 3S: 1140 Business PArk Phase 5 Runoff Area=22.710 ac Runoff Depth>8.16"
Tc=10.0 min CN=89 Runoff=184.95 cfs 15.439 af
Pond 3P: Infiltration Basin 1 Peak Elev=14.70' Storage=215,900 cf Inflow=184.95 cfs 15.439 af
Discarded=25.66 cfs 13.836 af Primary=55.25 cfs 1.594 af Outflow=80.91 cfs 15.430 af
Total Runoff Area = 49.230 ac Runoff Volume= 18.783 af Average Runoff Depth=4.58"

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 33
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment IS: Predeveloped Runoff Infiltration Basin 1
Runoff = 28.53 cfs @ 12.18 hrs, Volume= 2.863 af, Depth> 1.51"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 100-yr Rainfall=10.00"
Area (ac) CN Description
22.710 36 Woods, Fair, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Site
Subcatchment 1S: Predeveloped Runoff Infiltration Basin 1
Hydrograph
❑Runoff
30
Wit!
28
,� ;Runoff=28.53 cfs
Type 0124-hr 100;yr-
24
22_ , nfall=
-
ai 1 0.0,0
20-ERunoff Area_=22.710 ac ..
18-
16 . Runoff,-Volume=2..J8.63:of
T. 14. Runoff Depth>1.51" -
12=,' ,
1
Tc-= 0.0_Irrin
S - CN=36
,
. /%J7j,
2- - 1,' 1 f�f_V-4:f.47
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin OCT 2020 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 34
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin 1
Runoff = 4.79 cfs @ 12.18 hrs, Volume= 0.480 af, Depth> 1.51"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 100-yr Rainfall=10.00"
Area (ac) CN Description
0.370 36 Woods, Fair, HSG A, DA 1
0.680 36 Woods, Fair, HSG A, DA 2
1.540 36 Woods, Fair, HSG A, DA 8
1.220 36 Woods, Fair, HSG A, DA 10
3.810 36 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Predeveloped Runoff to Tract East of Site
Subcatchment 2S: Predeveloped Runoff to Property East of Site within Infiltration Basin
Hydrograph
El Runoff
5- 14.79c1s 1
Runoff=4.79 cfs
•
Type III 24-hr100tyr
10
4-
ROinf0111=10.09"
• . Runoff Are07.-L73.8.10 Oc_
3: Runoff,Volume=0A80:af
g
Runoff Depth>1.51"
2-, . Td=10.0
k' • CN=.36
1-4
'-" i
5 6 7 8 9 10 12' 13' -—14 15 16 17 18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 35
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Subcatchment 3S: 1140 Business PArk Phase 5
Runoff = 184.95 cfs @ 12.14 hrs, Volume= 15.439 af, Depth> 8.16"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type III 24-hr 100-yr Rainfall=10.00"
Area (ac) CN Description
19.178 98 Bldgs, Asphalt, Concrete
3.532 39 >75% Grass cover, Good, HSG A
22.710 89 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry, Entire Tract
Subcatchment 3S: 1140 Business PArk Phase 5
Hydrograph
O Runoff
190• .. ... ., ,. :... • 1184.95 ens I ,
1804 I'r . Runoff-184 .95::cfs...
160 Type III 24-tir100 yr
150
- Rainfall=10:00 140 "- ® a�22.71
.iA 120- - .
un ff Are O;arc
110; -
:Runoff 10ol:ume=t1:51439af
b 100'_
rr. 90_' . Runoff Depth;>8-1600
80 ,
7o=
=1min
. _N89
50_ •
404 A_
30 F. .
20`�. -I. i.
5 6 7 8 j' 1b 1,1 12. 15 14 15 116 17 (;
18 19 20
Time (hours)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 36
HydroCADO 7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
[82]Warning: Early inflow requires earlier time span
Inflow Area = 22.710 ac, Inflow Depth > 8.16" for 100-yr event
Inflow = 184.95 cfs @ 12.14 hrs, Volume= 15.439 of
Outflow = 80.91 cfs @ 12.40 hrs, Volume= 15.430 af, Atten= 56%, Lag= 15.8 min
Discarded = 25.66 cfs @ 12.40 hrs, Volume= 13.836 af
Primary = 55.25 cfs @ 12.40 hrs, Volume= 1.594 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 14.70'@ 12.40 hrs Surf.Area= 73,896 sf Storage=215,900 cf
Plug-Flow detention time=64.3 min calculated for 15.429 af(100% of inflow)
Center-of-Mass det. time=63.9 min (814.6-750.7)
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismatic)Listed below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 15.000 in/hr Exfiltration over Surface area
#2 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Discarded OutFlow Max=25.66 cfs @ 12.40 hrs HW=14.70' (Free Discharge)
4L-1=Exfiltration (Exfiltration Controls 25.66 cfs)
Primary OutFlow Max=55.09 cfs @ 12.40 hrs HW=14.70' (Free Discharge)
L2=Broad-Crested Rectangular Weir(Weir Controls 55.09 cfs @ 1.5 fps)

19131 Phase 51140 Basin OCT 2020 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 37
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
Hydrograph
84 95Outflow
�i
l+ �1 L
zoo flow A = 2.710 ac ®Primary
ed
In rea 2
1904 , ... --- - .W=1
180`- ... _. . ..
Inflo 84.95 cfs
170 .
_ Ou -tfLgW 80.�1- cfS-..
160'
150_ ?.
isc rded=�5.6-6 cfs
140='
130a ! ..
Plr...ry_: 55.25 _cfs:: .
To- 120' : , 1
1 11, .
_ - Pe
3 100 .eo.a,�, �. a ev � 4 70�
Storage215,900"cf.
80
70=
60_
� t:: r
30 /fir ii.=,. f �I
1 O %V(.4.4 I.////./�rr rr rrrr, �nr d I
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

19131 Phase 5 1140 Basin OCT 202 NO INFIL Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting • -- • Page 1
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
[821 Warning: Early inflow requires earlier time span
Inflow Area = 22.710 ac, Inflow Depth > 7.24" for 50-yr event
Inflow = 165.20 cfs @ 12.14 hrs, Volume= 13.709 af
Outflow = 142.66 cfs @ 12.21 hrs, Volume= 9.258 af, Atten= 14%, Lag=4.2 min
Primary = 142.66 cfs @ 12.21 hrs, Volume= 9.258 af
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 14.98'@ 12.21 hrs Surf.Area= 76,929 sf Storage= 237,255 cf
Plug-Flow detention time=135.2 min calculated for 9.256 af(68% of inflow)
Center-of-Mass det. time=65.8 min ( 818.5-752.7)
Volume Invert Avail.Storage Storage Description
#1 10.50' 238,588 cf Custom Stage Data (Prismatic)Listed below(Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
10.50 28,925 0 0
15.00 77,114 238,588 238,588
Device Routing Invert Outlet Devices
#1 Primary 14.35' 105.0' long x 10.0' breadth Broad-Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=141.22 cfs @ 12.21 hrs HW=14.98' (Free Discharge)
1=Broad-Crested Rectangular Weir(Weir Controls 141.22 cfs @ 2.1 fps)
Pedk 5'0 Eleo = 4.gia

19131 Phase 51140 Basin OCT 2020 NO INFIL Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris &Tunstall Consulting Engineers Page 2
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/9/20
Pond 3P: Infiltration Basin 1
Hydrograph
... _ .
IC Inflow
180 I 165.20... chi ®Primary
170 In
flow 22�7.10 ac
160
150
1„2.66 : n� ow=165-:20 cfs-
140
.
130 � - Primary=142.66 cfs
Peak Elev-14:98'
a
'°° Storage=237,255'.cf__.
3 90 ':
I
70
..
50
40
30
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

ig 131
Infiltraton Trench
CONCRETE, SIDEWALK
TOTALAREA(SF) ASPHALT(SF) CURB&GUTTER BUILDING(SF) OFFSITE(SF) IMPERVIOUS %IMPERVIOUS
(SF) (SF) TOTAL(SF)
DA5 12152 9106 607 1159 0 0 10872 89
DA7 13827 10351 576 1366 0 0 12295 89
DA9 13718 10302 567 1323 0 0 12192 89
DA11 14589 11169 572 1407 0 0 13148 90
DA14 909 827 86 0 0 0 913 100
DA17 1800 1611 183 0 0 0 1794 100
DA19 12406 9456 478 1235 0 0 11169 90
DA21 13724 10316 541 1355 0 0 12212 89
DA23 13727 10300 542 1332 0 0 12174 89
DA25 14187 10954 534 1412 0 0 12900 91
DA28 2387 1770 268 0 0 0 2038 85
DA31 3474 2743 202 0 0 0 2945 85
DA33 9814 7468 421 988 0 0 8877 90
DA35 18961 14521 722 1857 0 0 17100 90
DA37 9432 7151 483 905 0 0 8539 91
TOTAL(SF) 155107 118045 6782 14341 0 0 139168 89.7
TOTAL(AC) 3.56 2.71 0.16 0.33 0.00 0.00 3.19
4

Date Desigr NORRIS & TUNSTALL Wilmington, NC Sheet
IIIP —CONSULTING ENGINEERS P.C.— Brunswick County, NC
Of
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NORRIS & TUNSTALL Wilmington, NC Sheet
erzs--2-. .9e.. _CONSULTING ENGINEERS P.C.— Brunswick County, NC
Of
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tcvj4r:s ç1ffo . lie
S,ot i+ t`. -ii gals e 1
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(qqcr )
41:1 K 2S
Pre-Development Front Par ng Lot and
Runoff Drive ays of
Devel pment
A I Rowl'") e r/t-
'h a 4.k.
A
4 1 47tP i °&S. 1 $
Undergound Infiltration
System
19 sa = :°. � ,= • CFI fpi:4 3e4,...ee.i 4
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Oki ?eats 1:1e,40 ' I
177 oc
Subca Reach on Link�N� Drainage Diagram for 19131 Ph 51-140 Infiltration Pipe Trench June 20 0
Prepared by Norris&Tunstall Consulting Engineers 10/7/20
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC

19131 Ph 51-140 Infiltration Pipe Trench June 21:Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 2
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10R/20
Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre-Development Runoff Runoff Area=3.560 ac Runoff Depth=0.00"
Tc=5.0 min CN=30 Runoff=0.00 cfs 0.000 af
Subcatchment 2S: Front Parking Lot and Driveways of DevekRunoffArea=3.560 ac Runoff Depth=0.80"
Tc=5.0 min CN=92 Runoff=3.35 cfs 0.238 af
Pond 3P: Undergound Infiltration System Peak Elev=12.09' Storage=511 cf Inflow=3.35 cfs 0.238 af
Discarded=2.49 cfs 0.238 af Primary=0.00 cfs 0.000 af Outflow=2.49 cfs 0.238 af
Total Runoff Area = 7.120 ac Runoff Volume= 0.238 af Average Runoff Depth = 0.40"

19131 Ph 5 1-140 Infiltration Pipe Trench June 21Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 3
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 1 S: Pre-Development Runoff
[49] Hint: Tc<2dt may require smaller dt
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af, Depth= 0.00"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt=0.05 hrs
Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Area (ac) CN Description
3.560 30 Woods, Good, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front portion of Site
Subcatchment 1S: Pre-Development Runoff
Hydrograph
E Runoff
Runoff=0.00 'cfs
1
;Type III 24-hr 1.5 inch Storm
Rainfall=1.50°
Runoff Area=3.560 ac
Runoff Volume=0.000 of
Runoff Depth=0.00°°•
LL Tc=5:0 min'
CN=30
0.00 cts
o 5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142434445464748
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench June 21ype III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 4
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 2S: Front Parking Lot and Driveways of Development
[49] Hint: Tc<2dt may require smaller dt
Runoff = 3.35 cfs @ 12.08 hrs, Volume= 0.238 af, Depth= 0.80"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Type III 24-hr 1.5 inch Storm Rainfall=1.50"
Area (ac) CN Description
3.190 98 Paved parking & roofs
0.370 39 >75% Grass cover, Good, HSG A
3.560 92 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front Parking Area
Subcatchment 2S: Front Parking Lot and Driveways of Development
Hydrograph
I
ri Runoff
Runoff 3.35 cfs
31 Type Storm
III 24-hr 1�.5 inch
' I ` • , : Rainfall=1.50"•
• ; : • • : : • Runoff Area=3.560 ac
:
•
• • ;• ;• ; : • Runoff Volue=038-af
2-
• Runoff Depth=0.80".
Tc=50 nlin
1- 0 ; ;
f.
:�flit
5 6 7 8 9101112131415161718"192021222324252627282930313233343536373839404142434445464748
Time (hours)

19131 Ph 51-140 Infiltration Pipe Trench June 20"ype 111 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 5
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 10R/20
Pond 3P: Undergound Infiltration System
Inflow Area = 3.560 ac, Inflow Depth = 0.80" for 1.5 inch Storm event
Inflow = 3.35 cfs @ 12.08 hrs, Volume= 0.238 af
Outflow = 2.49 cfs @ 12.05 hrs, Volume= 0.238 af, Atten= 25%, Lag= 0.0 min
Discarded = 2.49 cfs @ 12.05 hrs, Volume= 0.238 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Peak Elev= 12.09'@ 12.15 hrs Surf.Area= 14,925 sf Storage= 511 cf
Plug-Flow detention time=2.1 min calculated for 0.237 af(100% of inflow)
Center-of-Mass det. time=2.1 min (829.6- 827.4 )
Volume Invert Avail.Storage Storage Description
#1 12.00' 24,223 cf Custom Stage Data (Prismatic)Listed below
74,625 cf Overall- 14,066 cf Embedded = 60,559 cf x 40.0%Voids
#2 12.50' 14,066 cf 36.0"D x 995.00'L Horizontal Cylinderx 2 Inside#1
38,290 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
12.00 14,925 0 0
17.00 14,925 74,625 74,625
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 7.220 in/hr Exfiltration over Surface area
#2 Primary 17.00' 24.0" Horiz. Orifice/Grate X 4.00 Limited to weir flow C= 0.600
iscarded OutFlow Max=2.49 cfs @ 12.05 hrs HW=12.05' (Free Discharge)
=Exfiltration (Exfiltration Controls 2.49 cfs)
Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=12.00' (Free Discharge)
2=Orifice/Grate (Controls 0.00 cfs)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2tType III 24-hr 1.5 inch Storm Rainfall=1.50"
Prepared by Norris & Tunstall Consulting Engineers Page 6
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
Hydrograph
il Inflow
3.35 eh _I OUi1IOW
I ' 1 I n flow ail Discaryed
-; , , - Prima
�4ras3.5-60 ac
Inflow=3.35 cfs
3 ._ae ore
Outflow=2.49 cfs
♦
d
Disc..a rde =2.-4 9 cfs- -
Primary=0.00 cfs
3 2 Peak; Elev=12109'
LL , ,i0 . .
Storage=511 c'f
/ '
6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 7
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre-Development Runoff Runoff Area=3.560 ac Runoff Depth=0.00"
Tc=5.0 min CN=30 Runoff=0.00 cfs 0.000 af
Subcatchment 2S: Front Parking Lot and Driveways of DeveldRunoff Area=3.560 ac Runoff Depth>3.60"
Tc=5.0 min CN=92 Runoff=14.46 cfs 1.067 af
Pond 3P: Undergound Infiltration System Peak Elev=13.63' Storage=12,635 cf Inflow=14.46 cfs 1.067 af
Discarded=2.49 cfs 1.067 af Primary=0.00 cfs 0.000 af Outflow=2.49 cfs 1.067 af
Total Runoff Area = 7.120 ac Runoff Volume= 1.067 af Average Runoff Depth = 1.80"

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 8
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 1S: Pre-Development Runoff
[49] Hint: Tc<2dt may require smaller dt
[45] Hint: Runoff=Zero
Runoff = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af, Depth= 0.00"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Type Ill 24-hr 2-yr Rainfall=4.50"
Area (ac) CN Description
3.560 30 Woods, Good, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front portion of Site
Subcatchment 1S: Pre-Development Runoff
Hydrograph
, ; 111 Runoff
Runoff=0;00 cfs;
Type III 24-h'r 2�-yr:
Rai lfall�4.50"
: i = ! Runoff Area=3 560'ac
Runoff Volume=0 000 of
LL I Runoff Depth'=000"'
Tc=5.0 `nin'
CIV 3;0:
I
5 6 7 8 9101112131415161718192021222324252627282930313233343536373839404142434445464748
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 9
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 2S: Front Parking Lot and Driveways of Development
[49] Hint: Tc<2dt may require smaller dt
Runoff = 14.46 cfs @ 12.07 hrs, Volume= 1.067 af, Depth> 3.60"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Type III 24-hr 2-yr Rainfall=4.50"
Area (ac) CN Description
3.190 98 Paved parking & roofs
0.370 39 >75% Grass cover, Good, HSG A
3.560 92 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front Parking Area
Subcatchment 2S: Front Parking Lot and Driveways of Development
Hydrograph
16: :
RI Runoff
� I I ' 1
.
lb=
14=' R �I
unoff , * (ifs
13= Type I
- T . II 24=h'r-,2 ylr ...
Rainfall=4:50": _..
10- 56
ros
Ru60f.f Area=3.
• Runoff:Volume=1.067 of
0
_ , I
LL
ono
ept 60"
• T075.0.min:
=92, .
,
:
J
1 _ ,,, �. �/ fib// I
5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142434445464748
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 10
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
[82] Warning: Early inflow requires earlier time span
Inflow Area = 3.560 ac, Inflow Depth > 3.60" for 2-yr event
Inflow = 14.46 cfs @ 12.07 hrs, Volume= 1.067 af
Outflow = 2.49 cfs @ 11.70 hrs, Volume= 1.067 af, Atten= 83%, Lag= 0.0 min
Discarded = 2.49 cfs @ 11.70 hrs, Volume= 1.067 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Peak Elev= 13.63'@ 12.53 hrs Surf.Area= 14,925 sf Storage= 12,635 cf
Plug-Flow detention time=29.8 min calculated for 1.066 af(100% of inflow)
Center-of-Mass det. time=29.7 min (815.7-786.0)
Volume Invert Avail.Storage Storage Description
#1 12.00' 24,223 cf Custom Stage Data (Prismatic Jsted below
74,625 cf Overall- 14,066 cf Embedded = 60,559 cf x 40.0%Voids
#2 12.50' 14,066 cf 36.0"D x 995.00'L Horizontal Cylinderx 2 Inside#1
38,290 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
12.00 14,925 0 0
17.00 14,925 74,625 74,625
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 7.220 in/hr Exfiltration over Surface area
#2 Primary 17.00' 24.0" Horiz. Orifice/Grate X 4.00 Limited to weir flow C= 0.600
iscarded OutFlow Max=2.49 cfs @ 11.70 hrs HW=12.06' (Free Discharge)
=Exfiltration (Exfiltration Controls 2.49 cfs)
Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=12.00' (Free Discharge)
L2=Orifice/Grate (Controls 0.00 cfs)

19131 Ph 51-140 Infiltration Pipe Trench June 2020 Type III 24-hr 2-yr Rainfall=4.50"
Prepared by Norris & Tunstall Consulting Engineers Page 11
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
Hydrograph
4. , , i , ,
I, 46craf ow
.. . , _ Inflow
•
167 , ;. . Inflow.Area.=.3...56_0_.ac scaryed
D
Prima
15:
fs
w
14 I
or . 4.- C
13
- , . .O w=2 ut l0 49 cfs-
iLf 4_
11- :.. .....,._ Discarde.d= ` ...9
.� _cfs.
10.
: = J _ :00:'cfs
Primary=0
a:
Peak Elev= 363__
olra e
S � 1 ,65cf_
5: 2.48 cfe / II
.,... -iAl ' ':. , I , . 11
:
4' I
- 2.49 ch
g,
6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

19131 Ph 51-140 Infiltration Pipe Trench June 2020 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 12
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Pre-Development Runoff Runoff Area=3.560 ac Runoff Depth=0.22"
Tc=5.0 min CN=30 Runoff=0.11 cfs 0.066 af
Subcatchment 2S: Front Parking Lot and Driveways of Develeunoff Area=3.560 ac Runoff Depth>6.06"
Tc=5.0 min CN=92 Runoff=23.78 cfs 1.798 af
Pond 3P: Undergound Infiltration System Peak Elev=15.13' Storage=26,543 cf Inflow=23.78 cfs 1.798 af
Discarded=2.49 cfs 1.798 af Primary=0.00 cfs 0.000 af Outflow=2.49 cfs 1.798 af
Total Runoff Area= 7.120 ac Runoff Volume= 1.864 af Average Runoff Depth = 3.14"

19131 Ph 51-140 Infiltration Pipe Trench June 2020 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 13
HydroCAD D 7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 1S: Pre-Development Runoff
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.11 cfs @ 13.73 hrs, Volume= 0.066 af, Depth= 0.22"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Type III 24-hr 10-yr Rainfall=7.05"
Area (ac) CN Description
3.560 30 Woods, Good, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front portion of Site
Subcatchment 1S: Pre-Development Runoff
Hydrograph
0.115= �. . 1 ' i r . 1 Runoff
U.11? 110.11611 • I I ...
0.1054- = 0, ,,
� � Ru , , ff= , cfs
0.095 :Type III 24-hr'10 r. ..
0.09.
0.085 Rainfa;Il=705":
0.0754 ff a=
uno ; Q►r� 3 560 'ac
130.0653 Runoff V lume=0 6'61 af.
o
0.055= _ f D -
0.05 . _ _ ept 0.2
I�unof � h�
=5.0 n
CNI I3:O
0.03
0.025 ;
0.02'
0.0151
,
0.005 ,
5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142434445464748
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 14
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 2S: Front Parking Lot and Driveways of Development
[49] Hint: Tc<2dt may require smaller dt
Runoff = 23.78 cfs @ 12.07 hrs, Volume= 1.798 af, Depth> 6.06"
Runoff by SCS TR-20 method, UH=SCS, Time Span=5.00-48.00 hrs, dt= 0.05 hrs
Type III 24-hr 10-yr Rainfall=7.05"
Area (ac) CN Description
3.190 98 Paved parking & roofs
0.370 39 >75% Grass cover, Good, HSG A
3.560 92 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ftfft) (ft/sec) (cfs)
5.0 Direct Entry, Front Parking Area
Subcatchment 2S: Front Parking Lot and Driveways of Development
Hydrograph
; ;
267 ,.. I .. 1 I I El
123.78cfa1._. - .- - .. ..
24- '- Runoff,=23 7,8 cfs;-
_ T .„. e l l l 24-h r 10 r
20= P"
;Rainfa11=7:05" -.
16 Runoff i4 rea=3:560 ac
14: : I Runoff'Volume=1.798 af
LL ,2= f D �r
, Runof epth 6:06
8-
V
6
92: .
4-
iirrrt �
5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142434445464748
Time (hours)

19131 Ph 51-140 Infiltration Pipe Trench June 2020 Type Ill 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 15
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 10R/20
Pond 3P: Undergound Infiltration System
[82]Warning: Early inflow requires earlier time span
Inflow Area = 3.560 ac, Inflow Depth > 6.06" for 10-yr event
Inflow = 23.78 cfs @ 12.07 hrs, Volume= 1.798 af
Outflow = 2.49 cfs @ 11.55 hrs, Volume= 1.798 af, Atten= 90%, Lag= 0.0 min
Discarded = 2.49 cfs @ 11.55 hrs, Volume= 1.798 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Peak Elev= 15.13'@ 12.77 hrs Surf.Area= 14,925 sf Storage= 26,543 cf
Plug-Flow detention time=73.6 min calculated for 1.798 af(100% of inflow)
Center-of-Mass det. time=73.5 min (848.8-775.3)
Volume Invert Avail.Storage Storage Description
#1 12.00' 24,223 cf Custom Stage Data (Prismatic)Listed below
74,625 cf Overall- 14,066 cf Embedded = 60,559 cf x 40.0%Voids
#2 12.50' 14,066 cf 36.0"D x 995.00'L Horizontal Cylinderx 2 Inside#1
38,290 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
12.00 14,925 0 0
17.00 14,925 74,625 74,625
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 7.220 in/hr Exfiltration over Surface area
#2 Primary 17.00' 24.0" Horiz. Orifice/Grate X 4.00 Limited to weir flow C= 0.600
Discarded OutFlow Max=2.49 cfs @ 11.55 hrs HW=12.05' (Free Discharge)
=Exfiltration (Exfiltration Controls 2.49 cfs)
Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=12.00' (Free Discharge)
L2=Orifice/Grate ( Controls 0.00 cfs)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 10-yr Rainfall=7.05"
Prepared by Norris & Tunstall Consulting Engineers Page 16
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
Hydrograph
L ... 23.78 cis _. _... _.., -- _ ._. .-._.J_ _ _., ,7i In
flow
-, a=3.560 D Discarded
, Pr
imary
- flowAre
IIIIIIL
•
-at
24= ,
, ; Inflonr 23.78 Ccfs
.�. '. •.. A
i
20_ Outflow_.2.49-„
18= Discarded=2.49-dfs -
16 ,
- =0.00 cfs
Primary
,
3 I II
' .. =
o Peak
E leer 'I 5:1 I
10:
'S 25,54
forage ; 3 of
6- 2 49 cfs & : ._ ... ...
�i -
.$ - err//r.
6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 4.8
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 17
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment IS: Pre-Development Runoff Runoff Area=3.560 ac Runoff Depth=0.42"
Tc=5.0 min CN=30 Runoff=0.43 cfs 0.124 af
Subcatchment 2S: Front Parking Lot and Driveways of DevekRunoff Area=3.560 ac Runoff Depth>6.99"
Tc=5.0 min CN=92 Runoff=27.26 cfs 2.074 af
Pond 3P: Undergound Infiltration System Peak Elev=16.00' Storage=32,309 cf Inflow=27.26 cfs 2.074 af
Discarded=2.49 cfs 2.074 af Primary=0.00 cfs 0.000 af Outflow=2.49 cfs 2.074 af
Total Runoff Area = 7.120 ac Runoff Volume= 2.198 af Average Runoff Depth =3.70"

19131 Ph 51-140 Infiltration Pipe Trench June 2020 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 18
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 1S: Pre-Development Runoff
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.43 cfs @ 12.40 hrs, Volume= 0.124 af, Depth= 0.42"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Type Ill 24-hr 25-yr Rainfall=8.01"
Area (ac) CN Description
3.560 30 Woods, Good, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front portion of Site
Subcatchment 1S: Pre-Development Runoff
Hydrograph
0.46- ®Runoff
0.44- . ..[b1 ! ;
• 1
0.42= . I , . Runoff=0�443' cfs:
0.4
0.36- Type III 24 h'r'2:5-yr. _
0.34i - Ra;i nfa11=8-01,"' -
0.28a3i _ a , 35 a
,R unoff Are 60 e'
Runoff Volume= 0.124 of
3 0.241I• ,
b :
0.22- : D ���,
u off'
LL o.z R � epth'-'0 4 .
0.14 /'
0.12
// C1V;30'.
0.1 - .,�
0.080.0 /�%
0.04 a
1:/
5 6 7 8 9 10 11 1213 14 1516 1718192021 222324 5' 2627282930313233343536373839404142434445464748
Time (hours)

19131 Ph 51-140 Infiltration Pipe Trench June 2020 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 19
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 2S: Front Parking Lot and Driveways of Development
[49] Hint: Tc<2dt may require smaller dt
Runoff = 27.26 cfs @ 12.07 hrs, Volume= 2.074 af, Depth> 6.99"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Type III 24-hr 25-yr Rainfall=8.01"
Area (ac) CN Description
3.190 98 Paved parking & roofs
0.370 39 >75% Grass cover, Good, HSG A
3.560 92 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front Parking Area
Subcatchment 2S: Front Parking Lot and Driveways of Development
Hydrograph
m Runoff
-
26= , , : : : : : . : , ; I ' �unofif_
-27 26. c.
fs
24= . - 11
: ' type 11[ 24 hr25'' yr
22- � -
:
Rain 'I"'fa11�8�0
2,0 :
18, , , , , Off-A =
.R un
,
16� , ,.7g. : : Runoff, meii2'0 4' of
Volu -
14= De h'>
, mi Runoff: � .6.9
12
10= i
Tc 5.0 !rim-/� C,N -
8 Oil ! 9,2
•
4_
_ ,
jy f J ,
g
/t Z
5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142434445464748
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type I1124-hr25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 20
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
[82] Warning: Early inflow requires earlier time span
Inflow Area = 3.560 ac, Inflow Depth > 6.99" for 25-yr event
Inflow = 27.26 cfs @ 12.07 hrs, Volume= 2.074 af
Outflow = 2.49 cfs @ 11.40 hrs, Volume= 2.074 af, Atten= 91%, Lag= 0.0 min
Discarded = 2.49 cfs @ 11.40 hrs, Volume= 2.074 af
Primary = 0.00 cfs @ 5.00 hrs, Volume= 0.000 af
Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Peak Elev= 16.00'@ 12.91 hrs Surf.Area= 14,925 sf Storage= 32,309 cf
Plug-Flow detention time=93.4 min calculated for 2.071 af(100% of inflow)
Center-of-Mass det. time=93.2 min ( 866.1 -772.9)
Volume Invert Avail.Storage Storage Description
#1 12.00' 24,223 cf Custom Stage Data (Prismatic)Listed below
74,625 cf Overall- 14,066 cf Embedded = 60,559 cf x 40.0%Voids
#2 12.50' 14,066 cf 36.0"D x 995.00'L Horizontal Cylinderx 2 Inside#1
38,290 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
12.00 14,925 0 0
17.00 14,925 74,625 74,625
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 7.220 in/hr Exfiltration over Surface area
#2 Primary 17.00' 24.0" Horiz. Orifice/Grate X 4.00 Limited to weir flow C= 0.600
Qiscarded OutFlow Max=2.49 cfs @ 11.40 hrs HW=12.05' (Free Discharge)
T--1=Exfiltration (Exfiltration Controls 2.49 cfs)
Primary OutFlow Max=0.00 cfs @ 5.00 hrs HW=12.00' (Free Discharge)
2=Orifice/Grate (Controls 0.00 cfs)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 25-yr Rainfall=8.01"
Prepared by Norris & Tunstall Consulting Engineers Page 21
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
Hydrograph
' 'Inflow
127.28c(sJ
FlOutflow
_
30 ' ... ..,.. ' l
.. ove;. . .. ...In Area=3.560 ac. . 01JDiscarded
Primary
28= f .=
28- =-. .. . . ... . .... . .. .:. ... . ow=27�26...cfs
Infl
za= / _
- I
OutflO r=2.49 cfs.
=" • Discarded=2:49 cfs
20-" i
- 18- - a = .
is � �
I
Prim ry 0 00 cfs
-- 16:' I I I
_ _6,0
0 14- - - . Peak. Elev='I �.
i
- -
I
12iStorage- 32,309 df
10 ,
... .. ..... ,._.. I
8-
6_.' 2.49cfs I I I , . I L • 1 I I
4- ' . .
4,'J- III /.ri•.. ,%'i�
0 ,,, :OZ. , #����.',
6 8 10 12 14 16 18 20 22 24 2.6 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 22
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment IS: Pre-Development Runoff Runoff Area=3.560 ac Runoff Depth=0.68"
Tc=5.0 min CN=30 Runoff=0.98 cfs 0.202 af
Subcatchment 2S: Front Parking Lot and Driveways of Develeunoff Area=3.560 ac Runoff Depth>7.96"
Tc=5.0 min CN=92 Runoff=30.86 cfs 2.360 af
Pond 3P: Undergound Infiltration System Peak Elev=17.05' Storage=38,290 cf Inflow=30.86 cfs 2.360 af
Discarded=2.49 cfs 2.352 af Primary=0.82 cfs 0.008 af Outflow=3.32 cfs 2.360 af
Total Runoff Area = 7.120 ac Runoff Volume= 2.563 af Average Runoff Depth =4.32"

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 23
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 1S: Pre-Development Runoff
[49] Hint: Tc<2dt may require smaller dt
Runoff = 0.98 cfs @ 12.32 hrs, Volume= 0.202 af, Depth= 0.68"
Runoff by SCS TR-20 method, UH=SCS, Time Span=5.00-48.00 hrs, dt= 0.05 hrs
Type Ill 24-hr 50-yr Rainfall=9.01"
Area (ac) CN Description
3.560 30 Woods, Good, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front portion of Site
Subcatchment 1S: Pre-Development Runoff
Hydrograph
1 1 1 i ' Runoff
I O 98 cfa I ;
Runoff,=0:98, cfs
• Type III 24-h�r50-yr
Rainfall'=9'01
Runoff Area=3.560 ac'
Runoff Volume=0:202 of
Runoff D 8
Tc=5.0
CN--;30
0
5 6 7 8 91011121314151617181920212223242526Wii 30313233343536373839404142434445464748
Time (hours)

19131 Ph 51-140 Infiltration Pipe Trench June 2020 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris &Tunstall Consulting Engineers Page 24
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 2S: Front Parking Lot and Driveways of Development
[49] Hint: Tc<2dt may require smaller dt
Runoff = 30.86 cfs @ 12.07 hrs, Volume= 2.360 af, Depth> 7.96"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Type lil 24-hr 50-yr Rainfall=9.01"
Area (ac) CN Description
3.190 98 Paved parking & roofs
0.370 39 >75% Grass cover, Good, HSG A
3.560 92 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front Parking Area
Subcatchment 2S: Front Parking Lot and Driveways of Development
Hydrograph
34- i. El Runoff
32- :130•86 cfs I ; '
R,unpff=$0.86 cfs;
26 Type
:
24- . ! : all=
,
a f 901
22_ p 46
, uno e � � _
:
ffArea- Oac;
L 20 n
: R 3
•
Runoff Volume=2 60 af.
Li_ . •, Runoffs Depth>7.96',
123 ;
. :
_
8- .7
min
,
. C,N2 .
6
o� .i. ' ' f ff�ii�/riririrrrr�rii
5 6 7 8 9 101112131415161718192021222324252627282930313233343536373839404142434445464748
Time (hours)

19131 Ph 51-140 Infiltration Pipe Trench June 2020 Type III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 25
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
[82] Warning: Early inflow requires earlier time span
[93] Warning: Storage range exceeded by 0.05'
Inflow Area = 3.560 ac, Inflow Depth > 7.96" for 50-yr event
Inflow = 30.86 cfs @ 12.07 hrs, Volume= 2.360 af
Outflow = 3.32 cfs @ 12.81 hrs, Volume= 2.360 af, Atten= 89%, Lag=44.1 min
Discarded = 2.49 cfs @ 11.25 hrs, Volume= 2.352 af
Primary = 0.82 cfs @ 12.81 hrs, Volume= 0.008 af
Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Peak Elev= 17.05'@ 12.81 hrs Surf.Area= 14,925 sf Storage= 38,290 cf
Plug-Flow detention time=114.3 min calculated for 2.357 af(100% of inflow)
Center-of-Mass det. time= 114.0 min ( 884.9-770.9)
Volume Invert Avail.Storage Storage Description
#1 12.00' 24,223 cf Custom Stage Data (Prismatic)Listed below
74,625 cf Overall- 14,066 cf Embedded =60,559 cf x 40.0%Voids
#2 12.50' 14,066 cf 36.0"D x 995.00'L Horizontal Cylinderx 2 Inside#1
38,290 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
12.00 14,925 0 0
17.00 14,925 74,625 74,625
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 7.220 in/hr Exfiltration over Surface area
#2 Primary 17.00' 24.0" Horiz. Orifice/Grate X 4.00 Limited to weir flow C= 0.600
piscarded OutFlow Max=2.49 cfs @ 11.25 hrs HW=12.05' (Free Discharge)
'-1=Exfiltration (Exfiltration Controls 2.49 cfs)
Primary OutFlow Max=0.68 cfs @ 12.81 hrs HW=17.04' (Free Discharge)
2=Orifice/Grate (Weir Controls 0.68 cfs @ 0.7 fps)

19131 Ph 5 I-140 Infiltration Pipe Trench June 2020 Type III 24-hr 50-yr Rainfall=9.09"
Prepared by Norris & Tunstall Consulting Engineers Page 26
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
Hydrograph
_ 30.86
.....
Inflow' ' asJ ulw
34-1 Inflow Area3.560 ac-11 . 11 rye dEJ Primary
nfloW-3Q.86 30-
utf low_3.3
O2 cfs
: s d
Di car ed--1. -cfs
- .
Prima
.i r .. ... .. ._I.. .. ._
16 Peak Elev=1.705'
. :Stotage=38 290 .. 'f
I
8 • 3.32 ds
6 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 27
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points
Runoff by SCS TR-20 method, UH=SCS
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1 S: Pre-Development Runoff Runoff Area=3.560 ac Runoff Depth=0.99"
Tc=5.0 min CN=30 Runoff=1.74 cfs 0.294 af
Subcatchment 2S: Front Parking Lot and Driveways of DeveldRunoff Area=3.560 ac Runoff Depth>8.91"
Tc=5.0 min CN=92 Runoff=34.42 cfs 2.644 af
Pond 3P: Undergound Infiltration System Peak Elev=17.26' Storage=38,290 cf Inflow=34.42 cfs 2.644 af
Discarded=2.49 cfs 2.488 af Primary=9.08 cfs 0.156 af Outllow=11.58 cfs 2.644 af
Total Runoff Area= 7.120 ac Runoff Volume= 2.938 af Average Runoff Depth =4.95"

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 28
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 1 S: Pre-Development Runoff
[491 Hint: Tc<2dt may require smaller dt
Runoff = 1.74 cfs @ 12.15 hrs, Volume= 0.294 af, Depth= 0.99"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Type Ill 24-hr 100-yr Rainfall=10.00"
Area (ac) CN Description
3.560 30 Woods, Good, HSG A
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front portion of Site
Subcatchment 1 S: Pre-Development Runoff
Hydrograph
0 Runoff
Runoff=1474 cfs
Type III 244hr'100-yr:
Rainfall=10 00
Runoff Area=3.560ac
,- Runoff Volulme=0. -�2 94 af
LL Runoff Depth=0.99
Ta=5.0 rnin
CN=30:
i 4%Jff//!//f/f fririiirrirf
5 6 7 8 9..110 11 1213 1415 16 17181920 21 222324 25 26 27.L.293031 32 33 34 5i363738.819.A?041-;6434VZ.A4ViZt
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 29
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Subcatchment 2S: Front Parking Lot and Driveways of Development
[49] Hint: Tc<2dt may require smaller dt
Runoff = 34.42 cfs @ 12.07 hrs, Volume= 2.644 af, Depth> 8.91"
Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Type III 24-hr 100-yr Rainfall=10.00"
Area (ac) CN Description
3.190 98 Paved parking & roofs
0.370 39 >75% Grass cover, Good, HSG A
3.560 92 Weighted Average
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry, Front Parking Area
Subcatchment 2S: Front Parking Lot and Driveways of Development
Hydrograph
38= • .. t 1 ' 1... 1 . ®Runoff
36
34.42 di . .
I I I
- I I A
I Runoff=34*42 cfs,
32j ;_30j
' Type Ill 24=.hr,1100 yr
28= I
•
•
Raanfall 10 00"'26- I _ IRunoff-Area=3.060 ac
20- !
3 uno ,f Volume,=2 644 af. ..
18_ ,
R
" 16- f 91' , ..
I ,
i _ _
' un >:8'� ep � I
: T c •5.�D min-
: 1
8=
. •i I C,N 92
ioi , Or ' . . : : : . . : : : — , :2' _ T7 // I : : :
5 6 7 8 9 11011121'3 141516 171819 20212223 242526 272829 30313233 343536 37383940414243444546 4746
Time (hours)

19131 Ph 51-140 Infiltration Pipe Trench June 2020 Type III 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 30
HydroCAD®7.10 sin 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
[82] Warning: Early inflow requires earlier time span
[93] Warning: Storage range exceeded by 0.26'
[85] Warning: Oscillations may require Finer Routing>1
Inflow Area = 3.560 ac, Inflow Depth > 8.91" for 100-yr event
Inflow = 34.42 cfs @ 12.07 hrs, Volume= 2.644 af
Outflow = 11.58 cfs @ 12.37 hrs, Volume= 2.644 af, Atten= 66%, Lag= 18.2 min
Discarded = 2.49 cfs @ 11.15 hrs, Volume= 2.488 af
Primary = 9.08 cfs @ 12.37 hrs, Volume= 0.156 af
Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Peak Elev= 17.26'@ 12.37 hrs Surf.Area= 14,925 sf Storage= 38,290 cf
Plug-Flow detention time=109.8 min calculated for 2.644 af(100% of inflow)
Center-of-Mass det. time= 109.7 min ( 878.9 -769.3)
Volume Invert Avail.Storage Storage Description
#1 12.00' 24,223 cf Custom Stage Data (Prismatic)Listed below
74,625 cf Overall- 14,066 cf Embedded = 60,559 cf x 40.0%Voids
#2 12.50' 14,066 cf 36.0"D x 995.00'L Horizontal Cylinderx 2 Inside#1
38,290 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
12.00 14,925 0 0
17.00 14,925 74,625 74,625
Device Routing Invert Outlet Devices
#1 Discarded 0.00' 7.220 in/hr Exfiltration over Surface area
#2 Primary 17.00' 24.0" Horiz. Orifice/Grate X 4.00 Limited to weir flow C= 0.600
Discarded OutFlow Max=2.49 cfs @ 11.15 hrs HW=12.05' (Free Discharge)
L1=Exfiltration (Exfiltration Controls 2.49 cfs)
Primary OutFlow Max=8.00 cfs @ 12.37 hrs HW=17.21' (Free Discharge)
L2=Orifice/Grate (Weir Controls 8.00 cfs @ 1.5 fps)

19131 Ph 5 1-140 Infiltration Pipe Trench June 2020 Type 111 24-hr 100-yr Rainfall=10.00"
Prepared by Norris & Tunstall Consulting Engineers Page 31
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
Hydrograph
: ,. ._
' 134.42 ars l. _ - .. _ Inflow
38- Inflow Area=S.560 -at- Pnmary
Outflow
3s= i t , I ,
�,Discarded
1 _ . , nflow=84:42 ifs
30 : Outtlow=11:58'cf• S
26_ _ • •
Discarded= :49 cfs.. ..
24= ; •
F 2.2 Primary= S ifs
I i I I
90
,6: Peak, Elev=17 26
,
14_ Storage 38,290 cf
12= 1 ,
it m
Ai
6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
Time (hours)

19131 Ph 5 1-140 Infiltration Pipe Trench OCT 2020 NO IlNype 11124-hr50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 1
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
[82] Warning: Early inflow requires earlier time span
[93] Warning: Storage range exceeded by 0.72'
[88] Warning: Qout>Qin may require Finer Routing>1
[85]Warning: Oscillations may require Finer Routing>1
Inflow Area = 3.560 ac, Inflow Depth > 7.96" for 50-yr event
Inflow = 30.86 cfs @ 12.07 hrs, Volume= 2.360 af
Outflow = 49.01 cfs @ 12.05 hrs, Volume= 1.520 af, Atten= 0%, Lag= 0.0 min
Primary = 49.01 cfs @ 12.05 hrs, Volume= 1.520 af
Routing by Stor-Ind method, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs
Peak Elev= 17.72'@ 12.06 hrs Surf.Area= 14,925 sf Storage= 38,290 cf
Plug-Flow detention time=179.3 min calculated for 1.520 af(64% of inflow)
Center-of-Mass det. time=81.2 min (852.1 -770.9)
Volume Invert Avail.Storage Storage Description
#1 12.00' 24,223 cf Custom Stage Data (Prismaticjisted below
74,625 cf Overall- 14,066 cf Embedded = 60,559 cf x 40.0%Voids
#2 12.50' 14,066 cf 36.0"D x 995.00'L Horizontal Cylinderx 2 Inside#1
38,290 cf Total Available Storage
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
12.00 14,925 0 0
17.00 14,925 74,625 74,625
Device Routing Invert Outlet Devices
#1 Primary 17.00' 24.0" Horiz. Orifice/Grate X 4.00 Limited to weir flow C= 0.600
Primary OutFlow Max=46.19 cfs @ 12.05 hrs HW=17.68' (Free Discharge)
1=Orifice/Grate (Weir Controls 46.19 cfs @ 2.7 fps)

19131 Ph 5 1-140 Infiltration Pipe Trench OCT 2020 NO Iftype III 24-hr 50-yr Rainfall=9.01"
Prepared by Norris & Tunstall Consulting Engineers Page 2
HydroCAD®7.10 s/n 000479 ©2005 HydroCAD Software Solutions LLC 10/7/20
Pond 3P: Undergound Infiltration System
Hydrograph
t t ,
LI Inflow
Elrim
' 4 • , , , Pary'
_
;Iasi co I ;
50 , Inflow•Atea=3.560 ac
, . ,
45 ' , ' ' inflo30.86 Cf$
„
'- • ; li ' -Primary=49.01 cfs
, , ,
I
' 1 ' Peak: Elev=17:721
it2; 30
1111. :Sto eage=38,290 cf
,
I
io-]
5-:. , ./. 01 ''',-,,, -7
0: ....,''''''7 /1.7.A , ' •
6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48
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NEW HANOVER COUNT YST opf WATER DESIGN MANUAL
SECTION SO-PIPE SYSTEM DESIGN PROCEDURES
�� If (use. �,ches+.)
.
___-- -- FIGURE 50-14
(02.5 �e paNEW YORK DOT DISSIPATER METHOD FOR USE IN DEFINED CHANNELS
It' 7;s'i 434
Source: `Bank and Channel Lining Procedures",New York Department of
ay.c, Transportation,Division of Design and Construction. 1971
1
ASS
1�.iI 's x ,► Note: To use the following chart you must know:
1) Q full capacity
,, , . (CN-s,•r�) 2) Qio
5- Iuse hacke 3- 3) V full
I. 4) Vio
>x
:. 4 II
� e r- Where Q=discharge in cfs and V=velocity in fps.
? ESTIMATION OF STONE SIZE AND DIMENSIONS FOR CULVERT•APRONS
4, tt .4
Zee-0 r Step 1) Compute flow velocity Vo at culvert or paved channel outlet.
1 S r
'Xis-ert2 , CLi •
.• '' _
Step 2) For pipe culverts Do is diameter
t r For pipe arch, arch and box culverts,and paved channel outlets,
Do=(Ao) ,where A.=cross-sectional area of flow at outlet.
_ a q/ For multiple culverts,use Do= 1.25 x Do of single culvert.
. _ ? , eFi
Step 3) For apron grades of 10%or steeper,use recommendations for next
V w 6.914 higher zone. (Zones 1 through 6).
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ADOPTED SEPTEMBER 5, 2000 PAGE 50-25

NEW HANOVER COUNTY STORM WATER DESIGN MANUAL
SECTION 50-PIPE SYSTEA1 DESIGN PROCEDURES
FIGURE 50-15
RIPRAP APRON DIMENSION REQUIEM ENTS
•
LENGTH OF APRON TO PREVENT SCOUR
ZONE TO PROTECT HOLE USE L2
APRON MATERIAL CULVERT ALWAYS
1 STONE FILLING(FINE) CLASS A ) 3 X Do L2
4XDo
2 STONE FILLING(LIGHT) �"1 3 X Do 6 X Da
3 STONE FILLING(MEDIUM) CLAS ' —, 4 X Do 8 X D
4 STONE FILLING(HEAVY) CLASS 1 4 X Do 8 X Do
5 STONE FILLING(HEAVY) CLASS 2 5 X Do 10 X Do.
6 STONE FILLING(HEAVY) CLASS 2 6 X Do 10 X Do
Width=3 times pipe diameter(min)
DETERMINATION OF STONE SIZE FOR DUMPED STONE CHANNEL LINING
AND REVETMENTS
Step 1) Use figure F-18a to determine maximum stone size(e.g.for 12 fps
or 550 lbs.
Step 2) Use.figure F-18b to determine acceptable size range for stone(for
12 fps it is 125-500 lbs.For 75%of stone,and the maximum and
minimum range in weight should be 25-500 lbs.)
NOTE: In determining channel velocities for stone linings and revetment,
use the following coefficients of roughness:
Diameter .. Manning's Minimum Thickness
(inches) "n" of lining (inches)
Fine 3 0.031 . 9 12
Light 6 0.035 12 18
Medium 13 0.040 18 •24
Heavy 23 0.044 30 36
(Channels) (Dissipaters)
Source: Erosion and Sediment Control Planning and Design Manual,NC Department
of NRCD,Land Quality Section,September 1988,rev. 12/93.
ADOPTED SEPTEMBER 5,2000 PAGE 50-26

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„ l y L L P "Setting the Standard for Service"
. A,. Geotechnical • Construction Materials • Environmental • Facilities NC Reg'sieree Engrneer,n i=irm F-l0
NC.Registerel Gentogists F,m C-sGu
March 2, 2020 SC Registered'Engineering=rtm:i2j:'
Mr. John S. Tunstall, P.E.
Norris &Tunstall Consulting Engineers
2602 Iron Gate Drive
Wilmington, North Carolina 28412
Reference: Report of Seasonal High Water Table Estimation and Infiltration Testing
1-140 Business Park
Wilmington, New Hanover County, North Carolina
ECS Project No. 49.10786
Dear Mr. Tunstall:
ECS Southeast, LLP (ECS) recently conducted a seasonal high water table (SHWT) estimation
and infiltration testing within the stormwater control measure (SCM) area(s) off of US Highway
421 in Wilmington, New Hanover County, North Carolina. This letter, with attachments, is the
report of our testing.
Field Testing
On December 19th, 20th 2019 and February 27, 2020, ECS conducted an exploration of the
subsurface soil and groundwater conditions, in accordance with the NCDEQ Stormwater Design
Manual section A-2, at ten requested locations shown on the attached Boring Location Plan
(Figure 1). ECS used GPS equipment in order to determine the boring locations. The purpose
of this exploration was to obtain subsurface information of the in situ soils for the SCM area(s).
ECS explored the subsurface soil and groundwater conditions by advancing one hand auger
boring into the existing ground surface at each of the requested boring locations. ECS visually
classified the subsurface soils and obtained representative samples of each soil type
encountered. ECS also recorded the SHWT and groundwater elevation observed at the time of
the hand auger borings. The attached Infiltration Testing Form provides a summary of the
subsurface conditions encountered at the hand auger boring locations.
The SHWT and groundwater elevation was estimated at the boring locations below the existing
grade elevation. A summary of the findings are as follows:
Location SHWT R/ Groundwater
1-1 /4. p 76 inches q, 88 inches
1-2 / ,c' 62 inches g'JT 70 inches
kWl 1-3 Oise ?.
.SI 44 inches , 50 inches
1-4 /4,57 62 inches ",,4 68 inches
2r:i ....xy 1-5 ifergf 100 inches /7. 7 108 inches
6 qo 1-6 /'�./e) 63 inches 9. ' 70 inches
-w~".' 1-7 !7; 80 inches ,gyp.4C 90 inches
1-8 /r,d 66 inches /,A /r 71 inches
1-9 j7_, 36 inches 0 2. 42 inches
1-10 /,, ft.. 48 inches , 58 inches
r Ag7 r / " v I• it ! irr-jvoli
ECS Capitol Services.PLLC • ECS Florida;LLC • ECS Mid-Atlantic,LLC • ECS Midwest,LLC • ECS Southeast.LLP • ECS Texas,LLP
www.ecslimited.com

Report of SHWT Estimation and Infiltration Testing
1-140 Business Park
Wilmington, New Hanover County, North Carolina
ECS Project No. 49.10786
March 2, 2020
ECS has conducted ten infiltration tests utilizing a compact constant head permeameter near
the hand auger borings in order to estimate the infiltration rate for the subsurface soils.
infiltration tests are typically conducted at two feet above the SHWT or in the most restrictive
soil horizon. Tests in clayey conditions are conducted for durations of up to 30 minutes. If a
more precise hydraulic conductivity value is desired for these locations, then ECS recommends
collecting samples by advancing Shelby tubes and performing laboratory permeability testing.
Field Test Results
Below is a summary of the infiltration test results:
Location Description Depth Inches/
hour
I-1 Tan/orange fine to med. SAND 52 inches 26.77
1-2 Tan/orange fine to med. SAND 38 inches 28.28 1 ��'/
Tan/orange fine to med. SAND w/ v r
1-3 g clay lens 20 inches 20.77 A � �
1-4 Gray/tan fine to med. SAND 38 inches / ��
27.42
1-5 Tan/orange fine to med. SAND 70 inches 29.78
1-6 Brown/gray fine to med. SAND 39 inches 28.25 4,1.:I
1-7 Gray fine to med. SAND 56 inches 31.22
1-8 Brown fine SAND 36 inches 15.97 lri
s /
1-9 Tan/orange fine to med. SAND w/ 24 inches Aj ii' H
clay lens 14.37
1-10 Brown/gray fine SAND w/silt 24 inches 12.98 /- / 1'0
Infiltration rates and SHWT may vary within the proposed site due to changes in elevation, soil
classification and subsurface conditions.
Closure
ECS's analysis of the site has been based on our understanding of the site, the project
information provided to us, and the data obtained during our exploration. If the project
information provided to us is changed, please contact us so that our recommendations can be
reviewed and appropriate revisions provided, if necessary. The discovery of any site or
subsurface conditions during construction which deviate from the data outlined in this
exploration should be reported to us for our review, analysis and revision of our
recommendations, if necessary. The assessment of site environmental conditions for the
presence of pollutants in the soil and groundwater of the site is beyond the scope of this
geotechnical exploration.
2

ECS Repaii-s emflookS
Se prifeethrel Ffireyt S4WT ;s
PCS SOUTHEAST LLP ¢ , "Setting the Standard far Service"
Geotechnical • Construction Materials • Environrnen al • Facilities 'CRegrst.-^.d=nglneer:ngf=umF-1373
4C Re •:terr I G,alogrs's F.in C-44d
SC ntered Engmeenng Firm 3239
October 5, 2020
Mr.John S. Tunstall, P.E.
Norris&Tunstall Consulting Engineers
2602 Iron Gate Drive
Wilmington, North Carolina 28412
Reference: Report of Hydrogeologic Evaluation
Wilmington Trade Center
Wilmington, New Hanover County, North Carolina
ECS Project No. 49.10786-A
Dear Mr. Tunstall:
ECS Southeast, LLP (ECS) recently conducted a seasonal high water table (SHWT) estimation
and infiltration testing within the proposed stormwater control measure (SCM) area(s) off of US
Highway 421 in Wilmington, New Hanover County, North Carolina. (Figure 1). ECS was then
requested to provide a Hydrogeologic Evaluation of the site in accordance to the North Carolina
Department of Environmental Quality (NCDEQ) standard for relaxing the 24-inch separation
between infiltration systems and the SHWT. This letter, with attachments, is the report of our
evaluation.
Field Testing
On December 19th, 20"', 2019 and February 27, 2020, ECS conducted an exploration of the
subsurface soil and groundwater conditions, in accordance with the NCDEQ Stormwater Design
Manual section A-2, at ten requested locations shown on the attached Boring Location Plan
(Figure 1). ECS used GPS equipment in order to determine the boring locations. The purpose
of this exploration was to obtain subsurface information of the in situ soils for the SCM area(s).
ECS explored the subsurface soil and groundwater conditions by advancing one hand auger
boring into the existing ground surface at each of the requested boring locations. ECS visually
classified the subsurface soils and obtained representative samples of each soil type
encountered. ECS also recorded the SHWT and depth to groundwater observed at the time of
the hand auger borings. The attached Infiltration Testing Form provides a summary of the
subsurface conditions encountered at the hand auger boring locations.
The SHWT and depth to groundwater was estimated at the boring locations below the existing
grade elevation. A summary of the findings are as follows:
Location SHWT Groundwater
I-1 76 inches 88 inches
1-2 62 inches 70 inches
1-3 44 inches i 50 inches
1-4 62 inches 68 inches
1-5 100 inches 108 inches
i-6 63 inches I 70 inches
ECS Capitol Services,PLLC • ECS Florida,LLC • ECS Mid-Atlantic,LLC • ECS Midwest.LLC • ECS Southeast,LLP • ECS Texas,LLP
mon.ecslimited.corn

Report of Hydrogeologic Evaluation
Wilmington Trade Center
Wilmington, New Hanover County,North Carolina
ECS Project No.49.10786-A
October 5, 2020
1-7 80 inches 90 inches
1-8 66 inches 71 inches
1-9 36 inches 42 inches
I-10 48 inches 58 inches
ECS conducted ten infiltration tests utilizing a compact constant head permeameter near the
hand auger borings in order to estimate the infiltration rate for the subsurface soils. Infiltration
tests are typically conducted at two feet above the SHWT or in the most restrictive soil horizon.
Tests in clayey conditions are conducted for durations of up to 30 minutes. If a more precise
hydraulic conductivity value is desired for these locations, then ECS recommends collecting
samples by advancing Shelby tubes and performing laboratory permeability testing.
Field Test Results
Below is a summary of the infiltration test results:
Location Description Depth Inches/
hour
I-1 Tan/orange fine to med. SAND 52 inches 26.77
1-2 Tan/orange fine to med. SAND 38 inches 28.28
I-3 Tan/orange fine to med. SAND w/ 20 inches 20 77
clay lens
1-4 Gray/tan fine to med. SAND 38 inches 27.42
1-5 Tan/orange fine to med. SAND 70 inches 29.78
1-6 Brown/gray fine to med. SAND 39 inches 28.25
1-7 Gray fine to med. SAND 56 inches 31.22
1-8 Brown fine SAND 36 inches 15.97
1_9 Tan/orange fine to med. SAND w/ 24 inches 14.37
clay lens
1-10 Brown/gray fine SAND w/silt 24 inches 12.98
Infiltration rates and SHWT may vary within the proposed site due to changes in elevation, soil
classification and subsurface conditions.
Hydrogeologic Evaluation
There are required components listed in the NCDEQ Stormwater Design Manual in order to
reduce the 24-inch separation between infiltration systems and the SHWT. In order to evaluate
the hydrogeologic conditions of an area designated for an infiltration SCM, these components
are evaluated. The SCM in question is to be constructed between I-1 and 1-6 (i.e., in the area of
borings 1-1 through i-6), ECS will be averaging the data from these six borings for the purposes
of this report. Below are the required component descriptions for this site.
2

Report of Hydrogeologic Evaluation
Wilmington Trade Center
Wilmington, New Hanover County,North Carolina
ECS Project No. 49.10786-A
October 5, 2020
• The site is located in the Coastal Plain Physiographic Province. The Coastal Plain is
composed of seven terraces, each representing a former level of the Atlantic Ocean.
Soils in this area generally consist of sedimentary materials transported from the other
areas by the ocean and rivers. These deposits vary in thickness from a thin veneer along
the western edge of the region to more than 2,000 feet near the coast. The sedimentary
deposits of the Coastal Plain rest upon consolidated rocks similar to those underlying the
Piedmont and Mountain Physiographic Provinces. The groundwater flow direction is
believed to be to the east towards the Northeast Cape Fear River, based on surface
topography.
• The site was observed to vary in elevation by a few feet from the north to the south. The
site is bordered by commercial properties to the north and south, US HWY 421 to the
west and undeveloped woods to the east. No stormwater treatment SCM was observed.
No abandoned wells or rock outcrops were observed.
• Based on regional geology and observations made in a previous on-site geotechnical
boring approximately a half mile from the current study area advanced by ECS on
August 17, 2020 (see attached boring sounding logs), the site consists of surficial
deposits of sandy sediment with silt to a depth of approximately 50 feet. The Castle
Hayne Limestone underlies the surficial sediment at depths greater than 50 feet.
• The saturated infiltration rate, which is also referred to as the vertical hydraulic
conductivity rate, of the surficial sediment within the proposed SCM footprint was tested
and resulted in a value of approximately 26. inches per hour(53.8 feet/day), based on
the averaged values obtained from infiltration testing of borings I-1 through 1-6. The ratio
of vertical hydraulic conductivity to horizontal hydraulic conductivity (i.e., anisotropic
ratio) typically ranges between 0.1 and 0.5 for unconsolidated sediments, not including
clay. Site-specific horizontal hydraulic conductivity testing would be required to evaluate
the anisotropic ratio at the subject site. However, in lieu of this information, ECS has
estimated the site's anisotropic ratio as a means to assessing the site's horizontal
hydraulic conductivity. Based on grain sizes encountered at tested locations I-1 through
1-6 and the resulting vertical hydraulic conductivity values, it appears most likely that an
anisotropic ratio closer to the mid to upper end of the typical anisotropic ratio range
would yield horizontal hydraulic conductivity values that are more typical of the sediment
encountered at the tested locations. For I-1 through 1-6, an anisotropic ratio of 0.5 was
used. As such, utilization of an anisotropic ratio of 0.5 yields an average horizontal
hydraulic conductivity value at tested locations I-1 through 1-6 of approximately 107.6
feet/day. Based on this horizontal hydraulic conductivity value and the approximate
saturated unconfined aquifer thickness beneath the site (43.5 feet) (this thickness is
based on the geotechnical boring, which was terminated at 50 feet below the existing
grade elevation, and a depth to groundwater at the site of approximately 6.5 feet),
transmissivity (i.e., horizontal hydraulic conductivity multiplied by saturated aquifer
thickness)was estimated to be approximately 4,681 square feet per day.
3

Report of Hydrogeologic Evaluation
Wilmington Trade Center
Wilmington,New Hanover County,North Carolina
ECS Project No.49.10786-A
October 5, 2020
• The SHWT was observed between 36 and 100 inches below the existing grade elevation
at the locations tested.
• The surficial aquifer of the site consists of sandy conditions where groundwater is
assumed to flow under unconfined conditions. The site currently consists of
undeveloped areas. Stormwater is currently infiltrating into the natural areas. A
proposed infiltration SCM (infiltration system) is to be constructed in order to contain and
treat the runoff of the anticipated impervious areas.
• Groundwater recharge at the site in its current state consists of direct surface infiltration
of precipitation and irrigation water at the vegetated portions of the site and infiltration of
runoff of precipitation into the grassy areas of the site. The most prominent groundwater
receptor in the area is the Northeast Cape Fear River, which is approximately 1.0 mile to
the east of the site. The topography of the area is variable and the subsurface flow
media consists of clean sands which results in surface water movement in the swales
with most surface water removal by infiltration. The pre and post flow calculations for
the site will be generated by Norris &Tunstall Consulting Engineers, PLLC and will be
submitted separate from this report.
• A mounding analysis was generated utilizing the United States Geological Survey
(USGS) spread sheet solving the Hantush (1967) equation for groundwater mounding
beneath an infiltration basin. The data used for calculating the mounding conditions was
collected from site specific field data, design data, and soil characteristics. On the chart,
(R) represents a one inch storm event over a 12 hour period (i.e., a storm event
infiltration rate of 0.1667 feet/day for an infiltration period duration of 0.5 days). The
mounding analysis only accounts for precipitation that directly enters the stormwater
basin and does not account for stormwater runoff that will enter the basin. As such, ECS
recommends that post-flow design criteria, including stormwater basin drainage area, be
used to complete additional evaluation of potential groundwater mounding. Specific
yield (Sy) was estimated as 0.32, based on values for similar sediment types published
within the USGS Compilation of Specific Yield for Various Materials by A.I. Johnson,
1963. Horizontal hydraulic conductivity (K)was calculated based on infiltration rate data
measured in the field and is referenced in the text above. The value of 26.88 inches per
hour infiltration rate, which is comparable to a horizontal hydraulic conductivity rate of
approximately 107.6 feet/day, given the site's estimated anisotropic ratio, should be
used for this analysis and for the SCM design. Basin dimensions (X and Y) were
provided by Norris & Tunstall Consulting Engineers, PLLC (the site civil designer). A
mounding analysis was generated for the SCMs being designed using the data collected
from I-1 through 1-6, as these borings are located within the planned SCM footprint. As
previously discussed, the infiltration period duration (T) was assigned as 0.5 days to
simulate a one inch storm event over a 12 hour period. The USGS mounding
spreadsheet is only capable of calculating the maximum groundwater mounding height
and maximum thickness of the saturated zone at the end of a storm event, and is not
designed to calculate the rate of groundwater mounding subsidence. Thickness of
4

Report of Hydrogeologic Evaluation
Wilmington Trade Center
Wilmington, New Hanover County,North Carolina
ECS Project No.49.10786-A
October 5, 2020
saturated zone HI(0) was derived by subtracting the depth to the assumed confining
layer (approximately 50 feet) from the approximate depth to groundwater at the site (6.5
feet). The spreadsheet is included with the attachments. The maximum mounding at
the end of the storm event beneath the infiltration basin is calculated to be 0.045 feet.
Based on limited data collected at the site, ECS does not anticipate groundwater mounding
beneath the proposed stormwater retention basins resulting from precipitation directly entering
the infiltration basins and not accounting for potential stormwater runoff to exceed 0.045 feet
following a storm event of 1 inch over a 12-hour time period. Groundwater mounding would be
expected to subside significantly during a dry period of 5 days following the storm event. ECS
recommends that post-flow design criteria, including stormwater basin drainage area, be used
to complete additional evaluation of potential groundwater mounding.
Closure
ECS's analysis of the site has been based on our understanding of the site, the project
information provided to us, and the data obtained during our exploration. If the project
information provided to us is changed, please contact us so that our recommendations can be
reviewed and appropriate revisions provided, if necessary. The discovery of any site or
subsurface conditions during construction which deviate from the data outlined in this
exploration should be reported to us for our review, analysis and revision of our
recommendations, if necessary. The assessment of site environmental conditions for the
presence of pollutants in the soil and groundwater of the site is beyond the scope of this
environmental exploration.
ECS appreciates the opportunity to provide our services to you on this project. If you have any
questions concerning this report or this project, please contact us at(910)686-9114.
Respectfully,
ECS SOUTHEAST, LLP
gkzoot5 l/�i` 2,744APY
K. Brooks Wall Michael L. Maloy, C.P.G.
Project Manager Principal Geologist
bwalltu'�.ecslimited.com mmalovCa)ecslimited.com
910-686-9114 540-785-6100
Attachments: Figure 1 —Site/Boring Location Plan
Infiltration Testing Form
Geotechnical Boring Logs
USGS Mounding Spreadsheets
GBA Document
5

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Wilmington Trade Center Figure 1-Site Location Plan
Provided b : 1990 USGS
Wilmington, New Hanover County, 1- �'
North Carolina ����
ECS Project#49.10786-A �)
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APPROXIMATE BORING LOCATIONS
•
el APPROXIMATE GEOTECHNICAL SOUNDING LOCATION W —..,L E
SCALE SHOWN ABOVE •
ririllik i
1-140 Business Park Ph 5
Hanover County,
• Grov Figure 2—Boring Location Plan
Cherry e, New
North Carolina
Provided by: Google Earth
ECS Project#49.10786
December 2019, Feb. and Aug. 2020
I I'
KBW I 17.%

Infiltration Testing Form
1-140 Business Park PH 5
Wilmington, New Hanover County, North Carolina
ECS Project No. 49.10786
February 27, 2020
Location Depth USCS Soil Description
I-1 0-15" SP Gray fine SAND
15"-88" SP Tan/orange fine to med. SAND
Seasonal High Water Table was estimated to be at 76 inches below the
existing grade elevation.
Groundwater was encountered at 88 inches below the existing grade
elevation.
Test was conducted at 52 inches below existing grade elevation
Infiltration Rate: 26.77 inches per hour
Location Depth USCS Soil Description
1-2 0-26" SP Gray fine to med. SAND
16"-30" SM Brown silty SAND
30"-70" SP Tan/orange fine to med. SAND
Seasonal High Water Table was estimated to be at 62 inches below the
existing grade elevation.
Groundwater was encountered at 70 inches below the existing grade
elevation.
Test was conducted at 38 inches below existing grade elevation
Infiltration Rate: 28.28 inches per hour
Location Depth USCS Soil Description
1-3 0-15" SP Gray fine SAND
15"-18" SM Brown silty SAND
18"-50" SP Tan/orange f. to med. SAND w/clay lens
Seasonal High Water Table was estimated to be at 44 inches below the
existing grade elevation.
Groundwater was encountered at 50 inches below the existing grade
elevation.
Test was conducted at 20 inches below existing grade elevation
Infiltration Rate: 20.77 inches per hour

Infiltration Testing Form
1-140 Business Park PH 5
Wilmington, New Hanover County, North Carolina
ECS Project No. 49.10786
February 27, 2020
Location Depth USCS Soil Description
1-4 0-26" SP Gray/white fine to med. SAND
26"-30" SM Brown silty SAND
30"-70" SP Gray/tan fine to med. SAND
Seasonal High Water Table was estimated to be at 62 inches below the
existing grade elevation.
Groundwater was encountered at 68 inches below the existing grade
elevation.
Test was conducted at 38 inches below existing grade elevation
Infiltration Rate: 27.42 inches per hour
Location Depth USCS Soil Description
1-5 0-110" SP Tan/brown fine to med. SAND
Seasonal High Water Table was estimated to be at 100 inches below the
existing grade elevation.
Groundwater was encountered at 108 inches below the existing grade
elevation.
Test was conducted at 70 inches below existing grade elevation
Infiltration Rate: 29.78 inches per hour
Location Depth USCS Soil Description
1-6 0-34" SP Gray/white fine to med. SAND
34"-39" SM Brown silty SAND
39"-70" SP Gray/tan/orange fine to med. SAND
Seasonal High Water Table was estimated to be at 63 inches below the
existing grade elevation.
Groundwater was encountered at 70 inches below the existing grade
elevation.
Test was conducted at 39 inches below existing grade elevation
Infiltration Rate: 28.25 inches per hour

Infiltration Testing Form
1-140 Business Park PH 5
Wilmington, New Hanover County, North Carolina
ECS Project No. 49.10786
February 27, 2020
Location Depth USCS Soil Description
1-7 0-70" SP Gray/white fine to med. SAND
70"-80" SM Brown silty SAND
Seasonal High Water Table was estimated to be at 80 inches below the
existing grade elevation.
Groundwater was encountered at 90 inches below the existing grade
elevation.
Test was conducted at 56 inches below existing grade elevation
Infiltration Rate: 31.22 inches per hour
Location Depth USCS Soil Description
1-8 0-36" SP Brown fine SAND
36"-50" SM Brown silty SAND
50"-70" SP Tan fine to med. SAND
Seasonal High Water Table was estimated to be at 66 inches below the
existing grade elevation.
Groundwater was encountered at 71 inches below the existing grade
elevation.
Test was conducted at 36 inches below existing grade elevation
Infiltration Rate: 15.97 inches per hour
Location Depth USCS Soil Description
1-9 0-24" SP Brown/tan fine SAND
24"-36" SM Tan/orange fine SAND w/clay lens
50"-70" SP Tan fine to med. SAND
Seasonal High Water Table was estimated to be at 36 inches below the
existing grade elevation.
Groundwater was encountered at 42 inches below the existing grade
elevation.
Test was conducted at 24 inches below existing grade elevation
Infiltration Rate: 14.37 inches per hour

Infiltration Testing Form
1-140 Business Park PH 5
Wilmington, New Hanover County, North Carolina
ECS Project No. 49.10786
February 27, 2020
Location Depth USCS Soil Description
-10 0-60" SW Brown/gray fine SAND w/silt
Seasonal High Water Table was estimated to be at 48 inches below the
existing grade elevation.
Groundwater was encountered at 58 inches below the existing grade
elevation.
Test was conducted at 24 inches below existing grade elevation
Infiltration Rate: 12.98 inches per hour

dt ECS Southeast,LLP
6714 Netherlands Drive
Fo5 Wilmington,NC 28403
i ,,,,,.:., -...A.. ECS Protect 0 22-29395
CPT:S-5
Project: Wilmington Trade Center Total depth:49.87 ft.Date:8/17/2020
Location: Wilmington,New Hanover County,North Carolina Cone Operator:Austin Fowler
Cone resistance Sleeve friction Pore pressure u o- SPT N60 o Seismic Velocity Norm.o Soil Behaviour Type
0 o a
2- 2- 2 2- 212 ._
4- 4- q 4- 4 4
6 6 6 6- 6_ 6 sadasIly •
8 8 a 8- 8- 8
10- 10- 10 10- 10- 10
12- 12- 12 12- 12- 12
Silynndas: • sill
14- 14- 14- 14- - 14- 14
16- 16- 16- 16- 16- 16 Sad
18- 18- 18- 18- 18- 18
20- 20- 20 20- 20- 20
22- 22- 22- 22- 22- 22
24- 24- s 24- 24- 24- 11 24
26- a 26- 15.26- 26- 4 t 26- G
26 •
CI 28- 28- 28- 28- 28- °28 �ndaslly,-•
30- 30- 30- 30- 30- 30
32- 32- 32- 32- 32- 32
34- 34- 34- 34- 34- 34
36- 36- 36- 36- 36- 36
38- 38- 38- 38- 38- 38
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42- 42- 42- 42- 42- 42
44- 44- 44- 44- 44- 44
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46- 46- 46 46- 46- 46
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48- 48- 481 48- 48- 48
50 • 50 d r 50 I5 50" 504 • i 50 .
0 200 0 1 0 10 20 0 10 20 30 40 50 60 0 500 1,000 0 4 8 12 16
Tip resistance(tsf) Friction(tsf) Pressure(psi) N60(blows/ft) Velocity(ft/s) SBTn(Robertson 1990)
CPeT-IT v.2.0.1.16-CPTU data presentation&interpretation software-Report created on:8/25/2020,10:00:29 AM 0
Project lie:I:IPRWKt5129351-29400%29395011soundlrs,_8les.cpt

This spreadsheet will calculate the height of a groundwater mound beneath a stormwater infiltration basin. More Information can be found in the U.S.Geological Survey
Scientific Investigations Report 2010-5102"Simulation of groundwater mounding beneath hypothetical stormwater infiltration basins".
The user must specify infiltration rate(R),specific yield(Sy),horizontal hydraulic conductivity(Kh),basin dimensions(x,y),duration of infiltration period(t),and the initial
thickness of the saturated zone(hi(0),height of the water table if the bottom of the aquifer is the datum).Fora square basin the half width equals the half length(x=y).For a
rectangular basin,if the user wants the water-table changes perpendicular to the long side,specify x as the short dimension and y as the long dimension.Conversely,if the user
wants the values perpendicular to the short side,specify y as the short dimension,x as the long dimension.All distances are from the center of the basin. Users can change the
distances from the center of the basin at which water-table aquifer thickness are calculated.
Cells highlighted in yellow are values that can be changed by the user.Cells highlighted in red are output values based on user-specified inputs.The user MUST click the blue
"Re-Calculate Now"button each time ANY of the user-specified inputs are changed otherwise necessary iterations to converge on the correct solution will not be done and
values shown will be incorrect.Use consistent units for all input values(for example,feet and days)
use consistent units(e.g.feet&days or inches&hours) Conversion Table
Input Values inch/hour feet/day
0.1667 R Recharge(infiltration)rate(feet/day) 0.67 1.33
0.320 Sy Specific yield,Sy(dimensionless,between 0 and 1)
107:60 K Horizontal hydraulic conductivity,Kh (feet/day)* 2.00 4.00 In the report accompanying this spreadsheet
150.000 x 1/2 length of basin(x direction,in feet)
(USGS SIR 2010-5102),vertical soil permeability
15.600 Y 1/2 width of basin(y direction,in feet) hours days (ft/d)Is assumed to be one-tenth horizontal
0300 t duration of infiltration period(days) 36 1.50 hydraulic conductivity(ft/d).
43.500 hi(0) initial thickness of saturated zone(feet)
I 43.54S I h(max) maximum thickness of saturated zone(beneath center of basin at end of infiltration period)
L 6.04 si Oh(max) maximum groundwater mounding(beneath center of basin at end of infiltration period)
Ground- Distance from
water center of basin
Mounding,in in x direction,In
feet feet
fi; a Re-Calculate Now
6u
1.
Groundwater Mounding,in feet
.` 2I 710 0.050
7 y..
90
- _ :Oda 100 0.035 •
-® .—.—__..,...- _.-.._ ...--._.,.....r,�__.®
4 . . 0.030 -
__.0Oi4 120
0.025 -----' --- .— _
0.020
0.015 ---
0,010 • --_— -----
0.005 - _._._...
0.000 --— —
0 20 40 60 50 100 120 140
Disclaimer --- -
This spreadsheet solving the Hantush(1967)equation for ground-water mounding beneath an infiltration basin
is made available to the general public as a convenience for those wishing to replicate values documented in the
USGS Scientific Investigations Report 2010-5102"Groundwater mounding beneath hypothetical stormwater
infiltration basins"or to calculate values based on user-specified site conditions.Any changes made to the
spreadsheet(other than values identified as user-specified)after transmission from the USGS could have
unintended, undesirable consequences.These consequences could include,but may not be limited to: erroneous
output,numerical instabilities,and violations of underlying assumptions that are inherent in results presented in
the accompanying USGS published report.The USGS assumes no responsibility for the consequences of any
changes made to the spreadsheet.If changes are made to the spreadsheet,the user is responsible for
documenting the changes and justifying the results and conclusions.

Important Information about This
• • •
,-- GeotechnicalEngineepuig Report
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.
While you cannot eliminate all such risks, you can manage them. The following information is provided to help.
The Geoprofessional Business Association (GBA) Typical changes that could erode the reliability of this report include
has prepared this advisory to help you—assumedly those that affect
a client representative—interpret and apply this • the site's size or shape;
geotechnical-engineering report as effectively • the function of the proposed structure,as when it's
as possible.In that way,clients can benefit from changed from a parking garage to an office building,or
from a light industrial plant to a refrigerated warehouse;
a lowered exposure to the subsurface problems
• the elevation,configuration,location,orientation,or
that,for decades,have been a principal cause of
weight of the proposed structure;
construction delays, cost overruns,claims,and • the composition of the design team;or
disputes. If you have questions or want more • project ownership.
Information about any of the issues discussed below,
contact your GBA-member geotechnical engineer. As a general rule,always inform your geotechnical engineer of project
Active involvement in the Geoprofessional Business changes-even minor ones-and request an assessment of their
Association exposes geotechnical engineers to a impact.The geotechnkal engineer who prepared this report cannot accept
wide array of risk-confrontation techniques that can responsibility or liability for problems that arise because the geotechnical
be of genuine benefit for everyone involved with a engineer was not informed about developments the engineer otherwise
construction project. would have considered.
This Report May Not Be Reliable
Geotechnical-Engineering Services Are Performed for Do not rely on this report if your geotechnical engineer prepared it:
Specific Purposes, Persons, and Projects • for a different client;
Geotechnical engineers structure their services to meet the specific • for a different project;
needs of their clients.A geotechnical-engineering study conducted for a different site(that may or may not include all or a
for a given civil engineer will not likely meet the needs of a civil-
portion of the original site);or
works constructor or even a different civil engineer.Because each • before important events occurred at the site or adjacent
geotechnical-engineering study is unique,each geotechnical- to it;e.g.,man-made events like construction or
engineering report is unique,prepared solely for the client.Those who environmental remediation,or natural events like floods,
rely on a geotechnical-engineering report prepared for a different client droughts,earthquakes,or groundwater fluctuations.
can be seriously misled.No one except authorized client representatives
should rely on this geotechnical-engineering report without first Note,too,that it could be unwise to rely on a geotechnical-engineering
conferring with the geotechnical engineer who prepared it.And no one report whose reliability may have been affected by the passage of time,
-not even you-should apply this report for any purpose or project except because of factors like changed subsurface conditions;new or modified
the one originally contemplated. codes,standards,or regulations;or new techniques or tools.If your
geotechnical engineer has not indicated an apply-by"date on the report,
Read this Report in Full ask what it should be,and,in general,if you are the least bit uncertain
Costly problems have occurred because those relying on a geotechnical- about the continued reliability of this report,contact your geotechnical
engineering report did not read it in its entirety.Do not rely on an engineer before applying it.A minor amount of additional testing or
executive summary.Do not read selected elements only.Read this report analysis-if any is required at all-could prevent major problems.
in full.
Most of the "Findings" Related in This Report Are
You Need to Inform Your Geotechnical Engineer Professional Opinions
about Change Before construction begins,gcotechnical engineers explore a site's
Your geotechnical engineer considered unique,project-specific factors subsurface through various sampling and testing procedures.
when designing the study behind this report and developing the Geotechnical engineers can observe actual subsurface conditions only at
confirmation-dependent recommendations the report conveys.A few those specific locations where sampling and testing were performed.The
typical factors include: data derived from that sampling and testing were reviewed by your
• the client's goals,objectives,budget,schedule,and geotechnical engineer,who then applied professional judgment to
risk-management preferences; form opinions about subsurface conditions throughout the site.Actual
• the general nature of the structure involved,its size, sitewide-subsurface conditions may differ-maybe significantly-from
configuration,and performance criteria; those indicated in this report.Confront that risk by retaining your
• the structure's location and orientation on the site;and geotechnical engineer to serve on the design team from project start to
• other planned or existing site improvements,such as project finish,so the individual can provide informed guidance quickly,
retaining walls,access roads,parking lots,and whenever needed.
underground utilities.
J

This Report's Recommendations Are perform their own studies if they want to,and be sure to allow enough
Confirmation-Dependent time to permit them to do so.Only then might you be in a position
The recommendations included in this report-including any options to give constructors the information available to you,while requiring
or alternatives-are confirmation-dependent.In other words,they are them to at least share some of the financial responsibilities stemming
not final,because the geotechnical engineer who developed them relied from unanticipated conditions.Conducting prebid and preconstruction
heavily on judgment and opinion to do so.Your geotechnical engineer conferences can also be valuable in this respect.
can finalize the recommendations only after observing actual subsurface
conditions revealed during construction.If through observation your Read Responsibility Provisions Closely
geotechnical engineer confirms that the conditions assumed to exist Some dient representatives,design professionals,and constructors do
actually do exist,the recommendations can be relied upon,assuming not realize that geotechnical engineering is far less exact than other
no other changes have occurred.The geotechnical engineer who prepared engineering disciplines.That lack of understanding has nurtured
this report cannot assume responsibility or liability for confirmation- unrealistic expectations that have resulted in disappointments,delays,
dependent recommendations if you fail to retain that engineer to perform cost overruns,claims,and disputes.To confront that risk,geotechnical
construction observation. engineers commonly include explanatory provisions in their reports.
Sometimes labeled"limitations,many of these provisions indicate
This Report Could Be Misinterpreted where geotechnical engineers'responsibilities begin and end,to help
Other design professionals'misinterpretation of geotechnical- others recognize their own responsibilities and risks.Read these
engineering reports has resulted in costly problems.Confront that risk provisions closely.Ask questions.Your geotechnical engineer should
by having your geotechnical engineer serve as a full-time member of the respond fully and frankly.
design team,to:
• confer with other design-team members, Geoenvironmental Concerns Are Not Covered
• help develop specifications, The personnel,equipment,and techniques used to perform an
• review pertinent elements of other design professionals' environmental study-e.g.,a"phase-one"or"phase-two"environmental
plans and specifications,and site assessment-differ significantly from those used to perform
• be on hand quickly whenever geotechnical-engineering a geotechnical-engineering study.For that reason,a geotechnical-
guidance is needed. engineering report does not usually relate any environmental findings,
conclusions,or recommendations;e.g.,about the likelihood of
You should also confront the risk of constructors misinterpreting this encountering underground storage tanks or regulated contaminants.
report.Do so by retaining your geotechnical engineer to participate in Unanticipated subsurface environmental problems have led to project
prebid and preconstruction conferences and to perform construction failures.If you have not yet obtained your own environmental
observation. information,ask your geotechnical consultant for risk-management
guidance.As a general rule,do not rely on an environmental report
Give Constructors a Complete Report and Guidance prepared for a different dient,site,or project,or that is more than six
Some owners and design professionals mistakenly believe they can shift months old.
unanticipated-subsurface-conditions liability to constructors by limiting
the information they provide forbid preparation.To help prevent Obtain Professional Assistance to Deal with Moisture
the costly,contentious problems this practice has caused,indude the Infiltration and Mold
complete geotechnical-engineering report,along with any attachments While your geotechnical engineer may have addressed groundwater,
or appendices,with your contract documents,but be certain to note water infiltration,or similar issues in this report,none of the engineer's
conspicuously that you've included the material for informational services were designed,conducted,or intended to prevent uncontrolled
purposes only.To avoid misunderstanding,you may also want to note migration of moisture-induding water vapor-from the soil through
that"informational purposes"means constructors have no right to rely building slabs and walls and into the building interior,where it can
on the interpretations,opinions,conclusions,or recommendations in cause mold growth and material-performance deficiencies.Accordingly,
the report,but they may rely on the factual data relative to the specific proper implementation of the geotechnical engineer's recommendations
times,locations,and depths/elevations referenced. Be certain that will not of itself be sufficient to prevent moisture infiltration.Confront
constructors know they may learn about specific project requirements, the risk of moisture infiltration by including building-envelope or mold
including options selected from the report,only from the design specialists on the design team.Geotechnical engineers are not building-
drawings and specifications.Remind constructors that they may envelope or mold specialists.
GEOPROFESSIONAL
s BUSIr ESS
B
* ASSOCIATION
Telephone:[phone]
e-mail:[e-mail] www.geoprofessional.org
Copyright 2016 by Geoprofessional Business Association(GBA).Duplication,reproduction,or copying of this document,in whole or i n part,by any means whatsoever,Is strictly
prohibited,except with GBAs specific written permission.Excerpting,quoting,or otherwise extracting wording from this document is perr:stted only with the express written permission
of GBA,and only for purposes of scholarly research or book review.Only members of GBA may use this document or its wording as a complement to or as an element of a report of any
kind.Any other firm,individual,or other entity that so uses this document without being a GBA member could be committing negligent