20240094 Ver 1_MallardCreekInterceptorPhase1_ResponseToNCDEQ_20240409

To:
CAROLINA WETLAND SERVICES, INC.
550 E. Westinghouse Blvd.
Charlotte, NC 28273
704-527-1177 (office)
704-527-1133 (fax)
Samantha Dailey
U.S. Army Corps of Engineers, Charlotte Regulatory Office
8430 University Executive Park Drive
Charlotte, NC 28262
Ms. Maria Schutte
NCDWR, 401 & Buffer Permitting Unit
512 N. Salisbury St., 9th Floor
Raleigh, NC 27604
Date: April 9, 2024
Subject: Response to Agency Comments (SAW-2024-00078, DWR # 24-0094)
Mallard Creek Interceptor - Phase 1
Mecklenburg County, North Carolina
CWS Project No. 2022-0018
Dear Ms. Dailey and Ms. Schutte,
Thank you for your emails requesting additional information and clarification regarding the Mallard
Creek Interceptor - Phase 1 Nationwide Permit No. 58 application and the Water Quality
Certification application. This letter is in response to your comments on the project.
NCDEQ Comments:
1.At streams and Mallard Creek, the surface impacts are similar for a jack and bore and open cut. For both
options, a cofferdam and bypass would be required, along with temporary bridge mat crossings for
equipment transfer over the stream. The cofferdam would still be required for jack and bore to prevent the
Mallard Creek from falling into the tunnel and for contingency planning in case unforeseen challenges arise
due to equipment malfunctions, unexpected soil conditions, or obstacles. While open cut methods would
result in installation of the sewer pipe within a week, jack and bore methods could last for months. Also, jack
and bores are not typically used for 84 in casing installation. Performing these large diameter sewer
trenchless installations requires massive tunnel shafts and an acre of land or more to set up tunneling
equipment.
2.13esides the stream crossings, areas where the limit of disturbance abuts the stream bank include
delineations of the existing sanitary sewer line easement. Therefore, some areas within the LOD abut the
stream bank, but the erosion and sediment control there is shown such that it is offset inland from the banks
(see Sheet C-3 near STA 1+43.43). For other areas where it appears the LOD abuts the stream bank
(Sheets C-4, C-5, C-6), the design drawings will be updated to show the silt fence off top of bank. Even with
this update, we'll probably need a waiver as we are following the existing sanitary sewer easement. While
construction shall occur off the stream bank, there are some areas where lateral connections need to be
plugged at the existing manholes which appear close to the creek (see Sheet C-9).
3.This impact is called out on sheet C-24 as S26 (Intermittent Stream N).

Mallard Creek Interceptor - Phase I April 9, 2024
Response to Agency Comments CWS Project No. 2022-0018
4. The main reason for non -perpendicular stream crossings is that design parameters of the project included
the proposed 60" sanitary sewer for the most part running parallel to the existing sanitary sewer. The existing
sewer will remain in place for future use. Each specific called -out crossing is addressed individually below.
- STA 4+00 on Sheet C-3 (Stream A)
The crossing of the proposed sanitary sewer and Stream A is not between the 75-104' requirement. The
sanitary sewer design in this area was made to reduce the number of manholes and construction impacts by
staying away from Mallard Creek and low topography. As seen on Sheet C-3, the existing sanitary sewer is
within a wetland (Wetland #20), therefore the design attempted to avoid any further wetland impacts by not
paralleling the existing sanitary sewer. However, this resulted in crossing Stream A at an angle that is not
perpendicular.
- STA 39+00 on Sheet C-6 (Stream D)
The crossing of the proposed sanitary sewer and Stream D is not between the 75-104' requirement. The
sanitary sewer design in this area was meant to reduce the overall impact by paralleling the existing sanitary
sewer line. A perpendicular sanitary sewer run would require additional manholes to make the bends or a
trenchless crossing underneath Mallard Creek, neither of which are financially feasible compared to the
current crossing.
- STA 145+60 on Sheet C-15 (Stream K)
The crossing of the proposed sanitary sewer and Stream K is not between the 75-104' requirement. The
sanitary sewer design in this area was meant to reduce the overall impact by paralleling the existing sanitary
sewer line. The proposed sewer design is perpendicular to Stream J in this location, but since Stream K is an
adjacent stream flowing into Mallard Creek via the same culverts, the sanitary sewer design crossing was not
perpendicular. The existing culverts move stream flow into Mallard Creek under the existing Mallard Creek
Greenway.
- STA 0+60 on Sheet C-21 (Stream H)
The crossing of the proposed sanitary sewer lateral and Stream H is not between the 75-104' requirement.
Numerous variables factored into the sanitary sewer connection design at this specific area. Variables
included the location of the proposed xCLT greenway trail (designed by others but being constructed
simultaneously with the proposed sanitary sewer project), existing Duke Energy R/W for transmission lines,
and making a sanitary sewer line connection from the existing sanitary sewer lateral to the proposed sanitary
sewer manhole at angles that would work for sewer flow.
5. Sheet C-28 is meant for the Charlotte Water Mallard Creek Wastewater Treatment Plant to portray the
route the contractor plans to use to access the plant to reach the project start location. There are many roads
and potential routes, but this is meant to show that the contractor will use the main road to avoid buildings
and tight turns when bringing in equipment. The image appears cut-off, but it is intentional to only show the
CLTW WRF property. There is no legend as the primary focus is not the sanitary sewer design but the
access route.
6. 1 have attached these.
7. The wider width is necessary due to the size of the new pipe. Because this new sewer line is being
installed in such a high density area, a 60" pipe is being installed to handle the capacity. This size pipe
requires a much deeper and wider trench. Because of the size and depth of the trenches, they need plenty of
Page 2 of 4

Mallard Creek Interceptor - Phase I
Response to Agency Comments
April 9, 2024
CWS Project No. 2022-0018
room to safely operate equipment along the sides without risking overloading the walls of the trench and
causing a collapse. Within the wetlands there are some areas where the trenches are over 20 feet deep and
exceed 25 feet in width.
8. Permanent easement widths varied from 50 ft to 30 ft and were typically offset from the existing sanitary
sewer easement. This resulted in areas where the proposed sanitary sewer centerline appears off -center
within the permanent easement mainly due to the location of proposed sanitary manholes. The permanent
easement will result in permanently maintained corridors in these areas for future maintenance. Due to the
proposed pipe size and depth, any future maintenance will need the permanent easement width to excavate,
bench down and fix the pipe if any maintenance is needed.
9. This project will not result in additional development that will impact downstream waters. This sewer
improvement is to provide increased capacity to existing infrastructure.
Please do not hesitate to contact Megan Bollero at 757-576-6433 or [e-mail] should
you have any questions or comments regarding this request.
Sincerely,
Megan Bollero, PWS
Project Scientist
.' /" A- " Z -'-, �
Aliisa Harjuniemi, PWS
Senior Project Manager
Attachments: Attachment A: Original comments from NCDEQ
Attachment B: Plan Sheets EC-1 - C-31
Page 3 of 4

Mallard Creek Interceptor - Phase 1
Attachments
April 9, 2024
CWS Project No. 2022-0018
Attachment A:
NCDEQ Comments

ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
RICHARD E. ROGERS. JR.
Director
NORTH CAROLINA
Environmental Quality
March 12, 2024
DWR # 20240094
Mecklenburg County
Charlotte Water
Attn: Mr. Michael Vaniska
5100 Brookshire Blvd.
Charlotte NC 28216
Delivered via email to: [e-mail]
Subject: REQUEST FOR ADDITIONAL INFORMATION
Mallard Creek Interceptor— Phase 1 Project
Dear Mr. Vaniska:
On January 9, 2024, with fee received on January 19, 2024, the Division of Water Resources (Division)
received your application requesting a 401 Individual Water quality from the Division for the subject
project. The Division has determined that your application is incomplete and cannot be processed. The
application is on -hold until all of the following information is received:
1. In the PCN Under Avoidance and Minimization it states, "Trenchless boring under the
stream...carries risk...option was abandoned from further consideration." Boring is used
throughout the state in various projects to minimize stream impact / potential WQ issues from
trenches. Further justification is needed to adequately document that all reasonable avoidance
and minimization efforts have been taken.
2. A few plan sheets show the limit of disturbance up to the top of streambank. Standard 401
Certification requirement states "Any utility construction corridor that is parallel to a stream or
open water shall not be closer than 10 feet to the top of bank or ordinary high-water mark." If
this requirement cannot be met in a specific location, please identify that location and provide
details of why the project cannot be modified to meet this condition. Please also submit a very
detailed construction sequence that includes additional measures that will be taken to protect
long term stream stability and to protect downstream water quality standards.
3. There is a tributary stream crossing near STA 0+00 on Plan sheet C-3 that is not included in
impacts. Please explain. See "What is this Crossing?" in image below.
VnYtlt C'arnlina Ih�artrrlent ctf knt itonntccttal (�ualic� I I)it iswn nt t1 seer 1Zehnurcrti
1_" Nrnrlh :tialishUn titn*ed 1 16l 1 Mad Scrt ice ('rmer I kilrtgh. North ('an)lYn:i ?7699-161 l
919.707.9000

Mallard Creek Interceptor— Phase 1- Project
DWR# 20240094
Request for Additional Information
Page 2of3
snag I PROa N. 3U'E. 1 , ,. — . 11 -
0+00 1+00 2+00 3+00 4+00
..... PROP. J6r c s49.64 (7)) .... .....
':YE-iAA0 9 ode
(TCLtFarAi�L1,TJNU1..CC, 'TEV="R.•44 �IP..TUPPAlK,'E
GL£aP.INGA'1GFI�EIN:'R.LI-1-.1. RE =97'6&= 1 UL-kRIN3hVL' '1-L1"'?IL;iMD1.
ARE4•`s.]L' S;r EX. 4V t. ky11CR
FRnPnYFb Se°..- PRrt/-. IF-0
SFNAf T+P. 3F FP - FWP. ' 7.. J:: °. iE AFAVI EC I)f'MEK- V ,T
(HFC SHFCT;::N• t:. ANC[ Tk)h i CONNL�CIICN llcl _'VL>• .",1V:3
�r ISEESREETC1t) 11 AT r%,°efl� `I.;; EE :: YE ET-r.11
Arr IN .;:bnnAs!` S C cl?
.-p( 5:1.,tS >. VrP4-r rn
-]. 11 u.1„lyt• 4, i3'Irri1, � _ ---U,. ""^.ti rµ
- N P
� # PPr ip•- 1S' - J
19rr rw r r T 21Er x
I� (:l � rPERNAV�NET plSTll R1SIt N::Ef � 'T '
- qr. ` �+.. V J1FtIN:, PNrt PIPE INts7w..riT1rf4 AR FAC76 9-'�
'BY C-HERS' 'a
(Snippet from plan sheet C-3. Reference for item 3 above)
4. The PCN states stream crossings meet standard requirements; however, there are stream
crossings (approximate locations below) that do not appear to be perpendicular. Standard 401
Certification requirement states, "Where there are temporary or permanent impacts from stream
crossings, utility lines shall cross the stream channel at a near -perpendicular direction (i.e.,
between 75 degrees and 104 degrees to stream bank)." Please explain/verify crossings are
between 75 degrees and 105 degrees to the stream bank and provide justification if not.
• STA 4+00 on Plan Sheet C-3 Labeled Perennial Stream A (also shown in image above and on
Plan Sheet C-18)
• STA 39+00 on Plan sheet C-6 Labeled Intermittent Stream D
• STA 145+60 on Plan Sheet C-15 Intermittent Stream K
• STA 0+60 on Plan Sheet C-21 Perennial Stream H
5. The Plan Sheet C-28 appears cut-off and there is no legend. Please correct as needed or clarify.
6. Many of the Erosion Control and Construction Plan Sheets are not legible when magnified. Submit
a higher quality copy of just these plan sheets (EC-1 to C-31) or also submit the information in a
separate document. Include specifics for each section of the project.
7. A waiver is requested for construction corridors in excess of 40 feet wide. Standard 401
Certification requirements state, "Construction corridors in wetlands and/or across stream
channels shall be minimized to the maximum extent practicable and shall not exceed 40 feet
wide." The request is reasonable for this type of project; however, the plans appear to show a
' Q � �^�,� �nrtll ('nmlina I)tp�rrmenl OfEfii�rrnnmrntal QualiLl� � I)it�isenq. nf11'arrr Resources✓ 9 Nmih Salmhun SLTecl 1 1611 Niml Str%Act ('enter I italetglt, North ('arohna -17699-[61 l
9 19. 707. L>GUU

Mallard Creek Interceptor— Phase 1- Project
DWR# 20240094
Request for Additional Information
Page 3of3
proposed width of 80 feet or more for most of the project. is this necessary? Note that
MINIMUM width of disturbance is the requirement.
8. Standard 401 Certification regulation states, "Permanent maintained access corridors in wetlands
and across stream channels shall be restricted to the minimum width practicable and shall not
exceed 30 feet wide." Many of the plan sheets reference permanent easements that appear to be
off the centerline of the proposed SS. Permanent easements are different than permanent,
maintained corridors. Do you intend to have permanent, maintained corridors wider than 30
feet? If so, justify.
9. On the PCN item G.3b. requires a narrative description. Please provide.
Pursuant to Title 15A NCAC 02H .0502(e), the applicant shall furnish all of the above requested
information for the proper consideration of the application. Please respond in writing within 30
calendar days of receipt of this letter by sending one (1) copy of all of the above requested information
to the 401 & Buffer Permitting Branch, 1617 Mail Service Center, Raleigh, NC 27699-1617 OR by
submitting all of the above requested information through this
link: https://edocs.deg.nc.gov/Forms/Supplemental-Information-Form (note the DWR# requested on
the link is referenced above).
If all of the requested information is not received within 30 calendar days of receipt of this letter, the
Division will be unable to approve the application and it will be denied as incomplete. The denial of this
project will necessitate reapplication to the Division for approval, including a complete application
package and the appropriate fee.
Please be aware that you have no authorization under the Section 401 of the Clean Water Act for this
activity and any work done within waters of the state may be a violation of North Carolina General
Statutes and Administrative Code.
Please contact Maria Schutte at 704-235-2184 [e-mail] if you have any questions
or concerns.
Sincerely,
DocuSigned by:
�a-4w H pa+,t4
F161F869A2a84A3..
Andrew H. Pitner, P.G., Regional Supervisor
Water Quality Regional Operations Section
Division of Water Resources, NCDEQ
Electronic cc: Megan Bollero, Carolina Wetland Services, Inc.
Samantha Dailey, USAGE Charlotte Regulatory Field Office
DWR 401 & Buffer Permitting Branch file
Filename: 20240094 Mallard Creek Interceptor — Phase 1 project - Mecklenburg - add info. docx
North Carolina Dcparintent of Ell; ironmental Qualily I pit imoo of Wirer Resources
rr
Q � 12 Noah. Salmhun StTect 1 1611 \Earl Scr%Ace. Center I italets la, North Carolina?7699-[61 l
n.F�MF.aN-mi.A �►"f 919.707.9000

Mallard Creek Interceptor - Phase 1
Attachments
April 9, 2024
CWS Project No. 2022-0018
Attachment B:
Sheets EC-1 - C-31

-
w ❑ � Q
U J
° r O
x �p
-
�
e=
b
.H H f OGa40 \ T11 oil
mN
S
S e gF ga
44a G �3 /yam
7- IrV�
ki
®p `J3c
ask
= oil
w
° „0 oNixm
Qua �1; 4
and
�G�� 03�� 65�� ���C':� HIM
0 <
„oa ❑ z �\ � P � � z� ����a�pp
El
ME
pp ❑ � Y � x
.�r 4N
��I3 0 •yla
haw gig w'
ko
Hg� dr �me
e O
i
lS
-... 1 1
b w ; € . O
—
e
Y a�3 � % 85 •�I {per
�jI 5
G
7m
�
zc� :oSh
mg�
Y
�zQ4
�s 'C

LLJ
'L-U-
[if
LLJ
C,
U)
E�
c
If
< [if
E2
LU
z LLJ
77
LU
0- cn -
R
-'o
IM
< . ....
8-�' T I-Rn
1� N
oo3 . .....
o
p-MA.--
o
o�
<
W
co
w
HH,
'o
-o-o-
-o o
o�
10
E-
-0
<
o
Rl
mH
W
o
.1 N,
2- -M
CD z
D
z
wl
'o
0 lzw
w
<
w T
. . . . . . . . . . . .
IZ Z, T

LLJ
c LC-U-,
o
[if
z
C, o
c)
0 z
0
U)
0
[if
LU
1— HiM
6
LU
�5
48
M
za
Mil
A HU
o
-H
------------ 15
­W
ne
oK
Hip
MH ... ...
N—E
M.
—ow 0.,
ESE—
WN 9 M
z .. .....
o
.z z mg a. inn 4
a min
o
Z.
Z_t
0
0 ZI Z_ -0 zo
Z­
A 2
o u I z I
0
'a2 111 311111 !!!!ill z
0
93 �-o
0 -.0
2
z FZ 0 A ,.Zpo o P. a ., m -
> who >o
-0 .0 UU- F. uo 0. �z F
Z.,
.0.
'o
E
ppl!,.Or4ffi;-Oi 'o
F -Z 4E z 'z Z4
�o 4 Mill '.0 .42
ZO
--o .0
"o w, '0
'o ouM9PM:p,-,.o -0 'z .0
0
U- --6!H9;o.Uo.
.1111;ga -0
HER 48 ua �, 0
Z1,2ZU4 .0. S 'o OM
6 .
0
4 4 pzz, o 1,
z
HIM
E�09!66919vg i '.o z tog,
0 9 �
WN AF 4
, NPRZ115. -St4.-.49
o o , F MoIl,81.04.I,
.10!'�!VMFIVO .546 0 _�o
4R UFF SOM"ffll!
-"Mog. Z 0
0
-4 z
14
4 4 �z 6.§.Zku"6�20N -10 10
o 0
u o ...
0 Hawk 2 5M 2 a 4
Z., z
OW212111, 01522Ig'6 1 M4
Mo.8 2ILZ
M—B . 2 M.,4z.14T.K

z
0
LLJ
Lu U)
0-
U)
z z
LU
LLB -
LLJ U J Lu
LU [If
C,
< [L)uf
Ef
(D
0
4
(D
a4 A
0
0
F7
c9
0
(D
F0
V
Uz. q
Mill, WO I q I
(D 111111, Piz H if
H,11�111 Hfllllmm
if-H H . 1� !,tlg
RAIr B. I ffil J] 1 111 W Hill 'at if 111HIM111 H-H Hil ln� H
0
FE
0
it
0
(D
Ed
IIISH
I W.. I BIH
H
EMU I
U-11
OHM pill H-11,
i
Hill

U) ml
LLI
Lu
U
4 e f
r
0 0
M
g 'o
5 W
m
ww
O g 0
o, <
. m
II : W v m
L€
-loll v
M
w w
<" 3g 9sa a
gci
�a� a s swg
A 1-10�111
o
nn
zoo � "sr
Oa3ed�.sa =s„ z 3 A.
o
W�-
"
z
w E r'r c� <
o o��oo�s
j - a3oor8 apo _� z
0 3p o��LL oo
two
U o
or=o -w o
a - w a
z - - �3z
¢ z H
u, o 10
z o°=ap - mow O _ - = 4 w 40
0 o o�- z mo �a �LLa z
z pa�W�= owo o ova �d
¢� oaw - o
Jz w
a
o
�w� 5
°_¢ �Fm w"w�Q 'owl
w a� oo �w �"od -
o as ❑
� o�ro�� piwW zWo �Q ° a oowr zNozmz o
�i $z a �g ogo o� o
p a op z oom 00.pwmm Qo boo z _� w�mp�YJ�Hwoo
z
owl z adzes
4
aJ _
z
a -
o
o
o
r
�aa Z per` �.p p3
F
Q O wgdo Nab o — a_a w_
ILI
-
D�od§ a