20180812 Ver 1_More Info Received_20150716

Johnson, Alan
From:Jorgensen, Elizabeth/ATL <[e-mail]>
Sent:Monday, July 16, 2018 3:35 PM
To:Johnson, Alan
Cc:[e-mail]; Bickel, Tom; Janiczak, Catherine M CIV USARMY
CESAW (US)
Subject:\[External\] RE: Kinder-Morgan DWR 18-0812
Attachments:IMG_0869.jpg; C - 9437 - KM - McGILLS BRANCH R1.pdf
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Good Afternoon Alan,

I am following up on your concerns about backwater as well as channel width with the proposed maintenance on the
Kinder Morgan pipeline in McGill’s Branch. We worked with the engineers to address your concern about the channel
width and the design was revised to create a 5 ft wide low flow channel (consistent with the current incised channel)
and provide the additional 3 feet terraced on either side (1.5 feet on each side) before sloping the banks upwards. This
would still carry the base flow in the smaller channel and also accommodate larger storm flow. This changes the volume
of fill below the OHWM due to the reshaped channel.

The new calculations on fill & cut are:
Grout Mat = 7cy
Sandbags = <1cy
Fill = 24cy
Cut = 13cy

The plan does call for raising the stream bed which is unavoidable. The engineers calculated the difference in elevation
as 12 inches. The stream banks are vertical upstream of the 10 inch pipeline and unexposed 26 inch pipeline and the
upper end of the proposed mat will be keyed in between these two pipelines. The water will back up behind the 10 inch
pipeline and due to the stream elevations it will likely temporarily create a backwater up to approximately 60 feet
upstream of the 10 inch pipeline with ~40 feet of that in the maintained ROW. The upstream backwater outside the
ROW would be within the incised channel (see attached photo) and would not cause flooding on adjacent land. It is
expected that suspended sediment will drop out of the water column and eventually raise the streambed and eliminate
the backwater area. The mats will function in that regard as a grade control structure to stabilize the upstream channel.
The matted area will provide a gradual elevation change along this stream reach rather than an abrupt headcut that can
impede the movement of aquatic organisms. This backwater will not be a new phenomenon as the 10 inch pipeline itself
created a backwater until the stream cut beneath the pipeline.

Please let me know if NCDENR or USACE would like to have a call about this or require additional information.

Thanks,
Betsy

Betsy Jorgensen
Jacobs
Project Manager/Environmental Scientist | ATEN
+ 01.678.530.4408
+ 01.404.435.0830 mobile
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From: Johnson, Alan \[mailto:[e-mail]\]
Sent: Monday, June 25, 2018 12:59 PM
To: Bickel, Tom
Cc: 'Shaeffer, David Leigh (Dave) CIV USARMY CESAW (US) ([e-mail])'
Subject: Kinder-Morgan DWR 18-0812

\[This email message was received from the Internet and came from outside of Kinder Morgan\]
I was reviewing the proposed project. The plan essentially calls for raising the bed of the stream about 15 inches to
cover the 10” exposed line. Creating a “hump” in the middle of the area to be stabilized, causing potential backwatering
(flooding) due to the increase elevation. What would the additional impact be with the back-flooding.

In addition the actual channel should be approximately 5 ft wide, your work would allow it to be 8 ft wide. But would
alleviate the ability of the stream flow to create a thalweg through the section to be impacted.

Not a perfect drawing, but conceptually the same as submitted.

Thanks
Alan Johnson

Alan D Johnson – Senior Environmental Specialist
NC Dept. of Environment & Natural Resources (NCDENR)
Division of Water Resources - Water Quality Regional Operations
610 East Center Ave., Suite 301, Mooresville, NC 28115
Phone: [phone] Fax: [phone]

E-mail correspondence to and from this address may be subject to the North Carolina Public Records Law and may be
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