20191029 Ver 4_401 Request Attachment_20211004

From:Riffey, Deanna
To:Andrew E Williams ; Ridings, Rob
Subject:I-5700 Construction Changes
Date:Friday, September 24, 2021 3:37:00 PM
Attachments:I-5700 Changes Comparison Sheet (2021-09-24).pdf
I-5700_Permit Drawing Modification_(2021-09-23).pdf
Good Morning,

I wanted to check with you both whether this email could suffice in lieu of a formal permit mod
package submittal for minor changes for I-5700. Division 5 has notified us on some necessary
changes that needs to be made prior to construction at Sites 5C, 6, and 7 (see attached plans). Site
5C is Brier Creek and Sites 6 and 7 are intermittent streams that connect to Brier Creek. Where
stream SA (Site 6) comes into Brier Creek (Site 5C) severe erosion has naturally taken placed and
has changed elevations since plans were developed. Brier Creek will be have a 48” RCP and will
provide a bit of water into this eroded area. Site 7 has had erosion issue as well and will need some
additional temporary changes. We are having to change the protection in this area of the project
where the three streams combine due to the future construction of the pipe system now being at
different elevations than was on plans and to account for erosion.

Currently, the rip rap bank stabilization on the west side of the Brier Creek was not extended down
to meet this tie in with SA leaving a gap in bank stabilization between the end of previously
proposed bank stabilization at Brier Creek and the new proposed rip rap associated with the tie in of
SA. We would like to extend the bank stabilization on the west side of Brier Creek to match the east
side at Site 5C to prevent erosion of the bank for the entire distance between the culvert outlet and
SA. No more permanent stream impacts will be added to what is there now due to the linear stream
impacts already on the east side and not adding anymore linear stream impacts. For Site 6 (SA), due
to the erosion of the channel along with elevation changes and the amount of water expected to be in
this channel, we would like to rip rap the channel at the tie in with Brier Creek. The rip rap will be
countersunk in the flow line and will be an additional 42 linear feet (52 linear feet total) of
permanent fill impact for SA. We were not planning to propose mitigation due to the additional 42 ft
being countersunk rip rap that will not impede the stream function. Site 5C will have temporary
impacts reduced from 53 feet to 26 feet and Site 6 will have now have 0 temporary impacts from the
proposed changes. No additional buffer impacts for either Site.

As for Site 7 (stream SB), due to limited access to the site to construct downstream channel
improvements, a temporary stream crossing was added at Permit Site 7. This temporary stream
crossing will be located within the footprint of the originally permitted 24 linear feet of temporary
stream impact to SB. However, an additional 10 linear feet of temporary stream impacts to SB is
proposed to allow for dewatering of the channel while the temporary stream crossing is constructed.

I have provided the permit plans for these changes with this email along with a Summary Sheet of
Changes Comparison for reference. Please let me know if you require a more formal letter for the
revisions for the three Sites.

GP 50 info: USACE – SAW-2019-02350 DWR: Project No. 20191029v2 12/22/20

Thank you,

Deanna Riffey
Environmental Program Consultant
Environmental Coordination and Permitting
Environmental Analysis Unit
North Carolina Department of Transportation

919 707 6151 office
[e-mail]

1598 Mail Service Center
Raleigh, NC 27699-1598

1020 Birch Ridge Drive
Raleigh, NC 27610