20200262 Ver 1_turbidity curtain question_20210216

Wanucha, Dave
From:Hining, Kevin J
Sent:Monday, February 15, 2021 8:50 AM
To:Wanucha, Dave
Subject:turbidity curtain question
Attachments:BR-0127_Permit Drawings.pdf; left abutment where turbidity curtain goes.JPG; right
abutment where turbidity curtain goes.JPG
Hey Dave,

We have three Raleigh permitted projects that are starting this spring that all involve turbidity curtains. They are all
three, fairly shallow, high velocity streams. The residing engineer for one of the projects (Yadkin 189) has already called
me to see if they have to install the curtains. I wouldn’t be surprised to hear grumblings from the contractor and our
staff about them blowing out at the other two projects (Wilkes 166 and Wilkes 663). But, I haven’t heard anything about
those two projects, so my plan is to let them try them out.

Regarding Yadkin 189 (permit and plans attached), the stream is surrounded by cattle (which should make things
interesting even without the turbidity curtain
????), and the stream is super shallow and primarily bedrock (see photos). I
don’t see any way that the curtains will be helpful at this project, but I do think they will be a maintenance issue and a
potential cattle issue due to the steel cables they use to keep them in place. In addition – I really can’t see what purpose
the turbidity curtain will serve, as they plan to leave the old abutments in the stream. So, there shouldn’t be any
instream work, and only 14 feet of permanent impacts (bank stabilization).

The one common denominator among all three of the bridges is that they were all designed by the same firm - STV. My
guess is they put them in all their plans, and I’m sure they probably work great in a slower piedmont or coastal plain
stream. In the future, I’ll try and question the need for these / head these off early on before the permit is issued. Since
these were Raleigh managed, I wasn’t involved as much as the typical, division led project.

For all of these projects, the turbidity curtain are not meant to be a dewatering device, so all crews will still dewater the
work area when needed (removing instream abutments, etc.). They seem to just serve as an additional measure. As I
mentioned, no one has asked to strike them from the plans at the other two bridges (Wilkes 166 and Wilkes 663). But,
hoping we can leave them off of Yadkin 189. More than happy to set up a site visit if you’d like to see it.

Thanks,

Kevin

Kevin Hining
Division 11 Environmental Officer
North Carolina Department of Transportation

828-386-7202 cell
[e-mail]

801 Statesville Rd.
PO Box 250
North Wilkesboro, NC 28659

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