20180087 Ver 1_Clemmons Response Letter_20180302

S&ME, Inc. | 9751 Southern Pine Boulevard | Charlotte, NC 28273 | p 704.523.4726 | f 704.525.3953 | www.smeinc.com
March 2, 2017 Electronic submittal
Division of Water Resources, Winston Salem Regional Office
Department of Environmental Quality
450 W. Hanes Mill Rd, Suite 300
Winston Salem NC 27105
Attention: Sue Homewood
[e-mail]
Reference: Response to Request for Additional Information
PNG Clemmons Area Upgrade, Line 443
DWR Project # 20188887
Davie County, North Carolina
S&ME Project No. 7435-17-015
Dear Ms. Homewood:
This letter is in response to your February 12, 2018 request for additional information received from the
NC Department of Environmental Quality (NCDEQ) - Division of Water Resources (DWR) regarding the
project referenced above. NCDEQ-DWR determined that our application was incomplete and could not
be further processed until items listed in this letter were addressed.
The following paragraphs presents NCDEQ-DWR comments in bold italics followed by our responses in
standard text:
Comment: 1. In order to further document Avoidance and Minimization, can you provide a map of
the 250-600 foott wide corridor that was assessed and all features found within that corridor
and/or other potential alignments for this new line. Can you also please provide a statement as to
the purpose for the new line. Does this connect existing lines? Provide services to a new
area/customer, etc.
Response: The purpose of the project is to strengthen reliability of the existing system by connecting
PNG’s Line 374 transmission pipeline at the southern end of the project area to a distribution line located
within the NCDOT right-of-way along Highway 158 at the north end.
A Google Earth KMZ file that depicts the project route and the extent of the delineated corridor has been
included with this electronic submittal for your review. Highlighted areas indicate areas where alternative
routes were considered, but ultimately eliminated from review based on environmental impacts, proximity
of more-developed areas, or previous property owner development plans. Where practicable, the route
was selected in order to adjoin existing utility easements, closely follow property boundaries, or be
constructed in areas that would otherwise minimize impact to the value of the owner’s property.
Response to Request for Additional Information S&ME Project No. 7435-17-015
PNG Clemmons Area Upgrade, Line 443 March 2, 2018
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Comment: 2. You have provided a typical flume stream crossing detail. The flume pipe is located
within the proposed pipeline alignment. It is unclear how a trench and pipeline will be constructed
below/within the same footprint as the flume pipe.
Response: Two methods of “in the dry” pipe installation, using either a flume pipe or dam-and-pump-
around system, have been proposed for this project. Both methods create a dry workspace for installation
of the pipe and prevent flowing water from coming in contact with the active work area. While the dam-
and-pump-around method is typically employed, the flume method is also an approved waterbody
crossing technique specified in the Federal Energy Regulatory Commission’s 2013 Wetland and
Waterbody Construction and Mitigation Procedures manual and was adopted for potential use on this
project. This method typically involves installation of the flume pipe in the channel prior to any trenching.
A sand bag/plastic sheeting diversion structure or equivalent is then constructed to develop an effective
seal and to divert stream flow through the flume pipe. Following proper sealing and alignment of the
flume pipe to prevent bank erosion and streambed scour, the trench is excavated through the dry stream
channel beneath the flume pipe and the pipe installed. The flume pipe is not removed during trenching,
pipe-laying, or backfilling activities. Following final cleanup of the stream bed and bank, the flume pipe
and dams are removed and water returned to the restored stream segment. A photograph of a flume
crossing is provided with this electronic submittal.
Providing both a detail for installation of the pipe using the flume method or dam-and-pump-around
allows the contractor the option of selecting the most appropriate method of “in-the-dry” installation
based on constructability and conditions encountered in the field.
Comment: 3. Please provide more explanation of what “safely accommodate construction” refers
to when provided as a justification for why temporary impacts will exceed 50 feet at some wetland
and stream locations.
Response: While the workspace at a majority of the wetland crossings has been reduced to 50 feet, PNG
has requested that the temporary workspace not be eliminated at wetland crossings WI, WL and portions
of WP and WZ. Experience with a similar project where the width of the construction corridor was limited
to 50 feet at wetland crossings created significant safety and constructability issues for the contractor. To
reduce the risk of worker injury or death by trench cave-ins or equipment tipping over in these wetland
areas, it was determined that 65 feet represents the minimum amount of necessary workspace necessary.
The additional temporary workspace at Wetland WZ is necessary to setup the bore rig for the Avgol drive
road bore. PNG originally explored an alternate route that would have avoided impacts to Wetland WZ.
However, future expansion of the adjacent Avgol facility into the area where the alternate route was
proposed eliminated that option from further consideration.
PNG does not propose to increase the amount of permanent easement at any of these locations, and will
limit the width of the permanently maintained corridor to 30 feet, as proposed for all other wetland areas.
Comment: 4. Please provide a detail for the channel to be constructed within the drained pond.
The detail should show the alignment of the channel, as well as a plan/profile and construction
sequence for the channel.
Response: A grading plan for the pond and new channel is included with this submittal.
Response to Request for Additional Information S&ME Project No. 7435-17-015
PNG Clemmons Area Upgrade, Line 443 March 2, 2018
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Thank you for your consideration of this additional information submittal. If you have questions or we can
provide anything else, please feel free to contact us at 704.523.4726.
Sincerely,
S&ME
Joey Lawler, PWS
Project Manager
Senior Reviewed by Chris Stahl, PE
Attachments:
Google Earth KMZ file
Photograph of flume crossing
Pond Grading Plan