20160299_FW R2536_ENV_SEC01 - Channel Stabilization_20161012

Wrenn, Brian L
From:Dilday, Jason L
Sent:Wednesday, October 12, 2016 7:26 AM
To:Wrenn, Brian L; '[e-mail]'
Subject:FW: R2536_ENV_SEC01 - Channel Stabilization
Attachments:IMG_1.pdf; IMG_2.pdf; IMG_3.pdf; 026-R2536_EC_psh08A.pdf; 027-R2536
_EC_psh08B.pdf
Brian and Andy,
Below is an email I received from the design build team for the Asheboro Bypass concerning a stream relocation. They
are having some problem with establishing grass on a section of the relocation. Because of the stipulation in their
contract that the consultants cannot directly contact agency members, I had Matt Cook summarize below what the
problem was. Please let me know what you think.

Jason

From: Matthew Cook \[mailto:[e-mail]\]
Sent: Tuesday, October 11, 2016 3:52 PM
To: Dilday, Jason L <[e-mail]>
Cc: Michael Prince <[e-mail]>; Tina Swiezy <[e-mail]>; Mike Merritt <[e-mail]>; Jim
Eisenhardt <[e-mail]>; Jeff Meador <[e-mail]>; Blakley, Reuben <[e-mail]>
Subject: R2536_ENV_SEC01 - Channel Stabilization

Jason

We have a location on the Asheboro Bypass where we are having issues establishing a grass lined channel. It is -L- 66+00
– 71+00 RT. This is the outlet of RCBC 100. It is a large channel relocation with overbanks. Currently no water has been
released in to it so that the liner can be established.

The contractor finished construction of this channel over a month ago. This is shown in the attached pdf 026-
R2536_EC_psh08A.pdf, the first phase of the RCBC construction sequence. Our plan was to sod the bottom and low
flow banks so that it would stabilize quickly. This would then allow us to release water through it. DWR advised against
this because fescue sod is not considered a native seed. So, the contractor seeded the area. Prior to Hurricane
Matthew, they had seeded it three times in the last five weeks. They also had their seeding contractor on site yesterday
to see what additionally they could do. From the attached pictures, you can see that the seed in some locations has
taken root and is becoming established, especially at the pic taken closest to the proposed RCBC outlet. IMG_3.pdf was
taken near the outlet of the proposed RCBC facing upstream, IMG_2.pdf was taken half way down the channel facing
upstream, and IMG_1.pdf was taken where the channel ties in to the existing stream facing upstream. In order to move
to phase 2 (attached 027-R2536_EC_psh08B.pdf), the channel needs to be stabilized. The contractor has even been
using the water truck to try to water the area when it hasn’t rained. The pics attached were taken October 10 which is
about 24 hours after they had just received 4” of rain from Hurricane Matthew. The site is holding up well.

There is some grass established. The standing water near the stream tie in is due to the erosion control device there
keeping it from leaving the site. Also, this area is more shaded than the areas near the proposed RCBC outlet. If we are
allowed to release water through the channel, this would essentially remove almost 1200’ of meandering jurisdictional
stream through the site and place it in a stable plastic lined channel. The RCBC construction could then begin.

My question is how much grass is needed to be considered stable? The bottom of the channel currently is not erodible
material since it has been lined with coir fiber matting. Also, jurisdictional streams do not generally exhibit grass in the
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flow line. While we realize the necessity to not allow sediment to leave the site, once water is released through this
channel the grass will probably die off due to the constant presence of water. I am asking this because we want to do
what is right, but we don’t want to wait another month to establish grass that is going to die when the water is
released. Are we primarily waiting for grass to become established on the overbanks?

Please feel free to forward this to Brian Wrenn and Andy Williams. We would like to have their input as well. We are
also having our monthly ride through next Tuesday, October 18 and would like them to come. Any guidance you can
provide would be welcomed. Thanks.

___________________________________

Matthew L. Cook, P.E.

Project Manager

RK&K
900 Ridgefield Dr., Suite 350
Raleigh, NC 27609

919.878.9560 P | 919.653.7350 D
www.rkk.com

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