20230684 Ver 1_ltr_ncdeq_add_info_clt10_20230915_fnl_20230915

Stantec Consulting Services Inc.
521 East Morehead Street, Suite 425
Stantec Charlotte NC 28202-2695
September 15, 2023
Ms. Sue Homewood
401 & Buffer Permitting Branch Division of Water Resources
North Carolina Department of Environmental Quality
512 North Salisbury Street
Raleigh, North Carolina 27699
Sue. [e-mail]
Reference: Additional Information: Boyd Farm Data Center; DWR# 20230684; Corps Action ID#
SAW-2023-00665; Catawba County
Dear Ms. Homewood,
On behalf of the applicant, Microsoft Corporation (Microsoft), Stantec Consulting Services Inc. (Stantec) is
pleased to submit this response to the North Carolina Department of Environmental Quality (DEQ) Division
of Water Resources' (DWR) email request for additional information dated September 5, 2023. Your
questions are presented first, followed by our answers in italics.
1. As the impacts have changed between the two responses, can you confirm that the impact amounts
within the response to the USACE are the most up to date and accurate information. And since the
impact amounts have changed twice since 404/401 application submittal, can you speak as to whether
the project is still undergoing design changes such that future impact changes may be possible.
Response: The impact amounts within the response to the USACE are the most up to date and
accurate information. The project design has been finalized and no further modifications resulting in
additional impacts are expected.
2. The responses provided indicate that the width of the proposed roads, and therefore the permanent
stream impacts, are because of utility line installation and spacing requirements. It would appear that
further avoidance and minimization could be accomplished by proposing burial of the utilities (some or
all) under the stream channel. This would allow for temporary impacts to the streams for the purpose of
utility installation, and permanent impacts to be reduced to the minimum necessary for the vehicular
road only. Please either modify the application in this manner, or provide sufficient justification for the
permanent loss of streams for the purpose of utility installation. Please note that the agencies regularly
receive applications for a wide variety of utility installation projects, including large interstate energy
pipelines, where installation is proposed as temporary impacts, therefore any justification for permanent
impacts should be related to unique aspects of this project rather than constructability, cost, east of
future maintenance, or any other activity that would be expected for other types of utilities.
Response: Duct banks, water lines, sanitary sewers and storm sewers are necessary utilities on data
center sites. The electrical and fiber duct banks make up the bulk of the utilities and are placed in the
roadbeds for the following reasons:
• Drainage issues: Duct banks are installed in such a way that the center of a duct bank run is
higher than both ends. Vaults connect duct bank runs. These slopes drain any condensation or
water that infiltrates the banks to the vaults where the water can be removed by a sump or other
drain. A diagram showing the installation requirements is provided in Figure 1 below (the structure
Design with community in mind

August 21, 2023
Ms. Sue Homewood
Page 2 of 3
Reference: Request for Additional Information: Boyd Farm Data Center; DWR# 20230684; Corps Action IN SAW-2023-00665;
Catawba County
labeled as "manhole" represents the buried vault and manhole access). Typically, vaults are
installed every 300' although that number can decrease depending on site conditions. A vault is
needed on either side of any stream or wetland crossing.
LEVEL GROUNC S URFfCE
CEWD443
3' MINIMUM
DUCT RUN
MANHOLE
https://constructionmanuals.tpub.com/14027/css/Ducts-and-Trenches-91.htm
Figure 1. Slopes for Duct Runs
Placing the duct banks under the streambed in such small, steep stream valleys would make this
type of sloping difficult, if not impossible. Installing short segments would not allow for adequate
drainage and could create conditions conducive to water collection in the duct banks that could
damage either fiber or electrical lines. The cross-section for the stream and valley at Impact SC4 is
provided in Figure 2 below.
835
.... L ......�...... ...... L ......I ....
835
830
830
825
PROPOSED GRADE----.—
825
T WIDE X IT HIGH BOX CULVERT (2)
820
820
HIGH FLOW CULVERT
815
815
LOW FLOW CULVERT
816
........ ... .. ...................
810
EXISTING GRADE
Bob
...........: ........... ...........
805
800
8D0
30" OF REINFORCED
7
BED MIX (INVERT 18"
HIGHERN LOW
SECTION A -A
FLOW CULVERT)
SCALE: HOR'I"=60'. VERT 1"=10'
Figure 2. Cross Section at Impact SC4
Design with community in mind

August 21, 2023
Ms. Sue Homewood
Page 3 of 4
Reference: Request for Additional Information: Boyd Farm Data Center; DWR# 20230684; Corps Action IN SAW-2023-00665;
Catawba County
• Installation of the duct banks: The size of duct bank and the required separation distance
between duct banks depend on the type of duct bank (electrical versus fiber optic). Would lead to
very large areas of temporary impacts and an additional mass grading operation of the surrounding
slopes. Typical duct bank cross -sections for this project are provided on Figure in Attachment 1.
Requirements dictate a 65-foot separation distance between fiber duct banks and the electrical duct
banks must be either 4 or 6 feet apart depending on size. The vaults installed at the end of each
duct bank run are large structures. Electrical vaults are large boxes measuring 11 feet on each side
and fiber vaults measure 12 foot 8 inches by 8 feet or 16 foot 11 inches by 9 feet 1 inch. Please
refer to Figures 2 and 3 in Attachment 1. Installation of duct banks and vaults is a massive
operation as shown on Figures 4 and 5 in Attachment 1.
Environmental: While constructing the duct banks under the stream would be considered
temporary impacts, installation of the duct banks and the vaults required to connect the duct banks
to the rest of the networks would include large areas of additional clearing and grading. This would
remove large areas of existing tree cover on the stream banks which are currently planned to be
preserved.
• Security: Duct banks and vaults must be located within security fencing as these are secure
facilities. If the ducts were placed through stream channels the security fencing would be expanded
around the crossings and, depending on visibility, may require permanent stream impacts for
perimeter access roads for use during daily security inspections.
• Safety: Installation of the duct banks in the stream valleys would put vaults more than 20' below
ground. The vaults must be easily accessible for regular inspection and maintenance of the cables.
Additionally, with the construction of each new building the vaults need to be opened for new fiber
installation.
The site plan layout was designed to maximize the area for required buildings and infrastructure
including stormwater ponds while avoiding and minimizing impacts to waters as well as the 100-year
floodplain. In addition to the constraints listed above, the following issues would also apply to the two
road crossings:
• Impact SA4 — Moving the utilities would not be possible due to the stormwater management facility
on the northeast side and the security entrance on the northwest side of the road crossing. Utilities
cannot be installed in the slopes of a stormwater facility. Stream SA also has very incised slopes on
the east side of the crossing. The site layout around Impact SA4 is provided in Figure 3 below. The
cross section is provided in Figure 6 of Attachment 1.
Design with community in mind

August 21, 2023
Ms. Sue Homewood
Page 4 of 5
Reference: Request for Additional Information: Boyd Farm Data Center; DWR# 20230684; Corps Action IN SAW-2023-00665;
Catawba County
-, Pond
ecurlty
Entrance
44Vi
LA
Figure 3. Site Layout at Impact SA4
• Impact SC4 — Moving the utilities would not be possible due to the stormwater management
facilities on the northeast and southwest sides of the road. The duct banks could not be moved to
the south because the applicant does not own the property in between the two pad sites. To the
north of the crossing and the pond there are steep slopes and an existing county sewer line that
would make installing duct banks behind the pond extremely difficult, if not impossible. The cross
section is provided in Figure 7 of Attachment 1.
Design with community in mind

August 21, 2023
Ms. Sue Homewood
Page 5 of 5
Reference: Request for Additional Information: Boyd Farm Data Center; DWR# 20230684; Corps Action IN SAW-2023-00665;
Catawba County
Pond
Property Line
Figure 4. Site Layout at Impact SC4
Thank you for your assistance with the permit applications. If I can be of further assistance, please contact
me at [phone] or amber.forestier(astantec.com if you have any questions.
Sincerely,
STANTEC CONSULTING SERVICES INC.
Amber Forestier
Senior Regulatory Specialist
Phone:[phone]
[e-mail]
Attachments: Attachment 1: Duct Bank Visuals
Cc: Krysta Stygar (USACE), Lexi Claire Wolanski (Microsoft), Loretta Cummings (Stantec)
Design with community in mind

Figure 1. Duct Bank Cross -Sections
FINISH GRADE
3'- s 1rz'
TYPICAL (24) 4" CONDUIT
DUCTBANK CONCRETE ENCASED
UNDER ROADWAY
FINISH GRADE
W
� I
3 1.4MiN
0
o —
PAVEMENT SECTION
WHERE APPLICABLE
COMPACTED SELECT BACKFI__
- DUCT BANK TO BE MARKED
WITH DETECTABLE WARNING
TAPE AS SPECI FIED
3500 PSI CONCRETE WITH #4
REBAR AT 8" O-C.
LONGITUDINALLY AND#4 TIES
AT 24" O-C.
REFER TO SPECIFICATION
SECTION 27 05 43-10 FOR
REQUIREMENTS
4-INCH CONDUIT (TYP" OF 24)
CONDUIT SUPPORTS
EVERY 5'-0°
4" THICK COMPACTED
SELECT BACFILL
PAVEMENT SECTION
WHERE APPLICABLE
COMPACTED SELECT BAC FILL
DUCT BANK TO BE MARKED
WITH DETECTABLE WARNING
TAPE AS SPECIFIED
3500 PSI CONCRETE WITH #4
REBAR AT 8" O-C-
LONGITUDINALLY AND #4 TIES
AT 24" O-C-
REFER TO SPECIFICATION
SECTION 27 05 43-10 FOR
REQUIREMENTS
4-INCH CONDUIT{TYP" OF 12)
CONDUIT SUPPORTS
EVERY 6-0"
IWIDTH AS REQUIRED � 4" THICK COMPACTED
SELECT BACKFILL
TYPICAL (12) 4" CONDUIT
DUCTBANK CONCRETE ENCASED

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