RE_ U-2579AB permit site 8 pipe perch

Amy,

Based on the conditions presented, I’m in agreement with the plunge pool changes and stabilization efforts proposed near the culvert outlet. As noted in the Detail EEE, geofabric should
be anchored to the stream banks with additional rip-rap pressed-in as needed.

Thanks for the opportunity to review.

Ryan Conchilla, PWS

Environmental Specialist II

401 and Buffer Transportation Permitting Branch

North Carolina Department of Environmental Quality

919-707-9111 office

[e-mail] <mailto:[e-mail]>

From: Euliss, Amy <[e-mail]>
Sent: Friday, February 9, 2024 3:24 PM
To: Brumagin, Stephen A (Steve) CIV USARMY CESAW (USA) <[e-mail]>; Conchilla, Ryan <[e-mail]>
Cc: Sawicki (Gannett Fleming), Jeremy P <[e-mail]>; Trantham, Darren K <[e-mail]>; Shaver, Larry B <[e-mail]>; James Meachum <[e-mail]>
Subject: U-2579AB permit site 8 pipe perch

Steve and Ryan,

On U-2579AB-permit site 8, we have very similar situation to what was encountered at Site 19 (see attached email chains for reference, one email from the USACE and another from DWR).
The origin of the stream was taken by the pipe impacts, which was also the scenario at site 19. So aquatic passage in the pipe system should not be a concern.

When installing the pipe system, several springs were found forcing us to use foundation conditioning material for bedding this drainage system in order to stabilize it. The stone that
was installed is now acting as an underdrain to the system that is relieving itself at the outlet end of the system. We’ve found that trying to establish any native material at or around
the outlet of the pipe simply can’t be maintained. In lieu of proposing lining the stream bed with stone triggering a permit modification and mitigation, we’re hoping the installation
of a plunge pool at this location would allow us to avoid the modification, and resolve the issue of the perched pipe, similar to last time. Attached is a revised plan sheet for the
site along with a current picture showing the perched outlet.

Please review and advise if you have any questions. They are actively working in the area. It would be helpful if you could provide a response before the end of next week (2.16).
Thanks in advance!

Amy Euliss

Division 9 PDEA Engineer

North Carolina Department of Transportation

336 747 7802 office

[e-mail] <mailto:[e-mail]>

375 Silas Creek Parkway

Winston Salem, NC 27127-7167

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