RE_ R-2566BA Watauga River

Wanucha, Dave
From:Hining, Kevin J
Sent:Sunday, October 23, 2022 11:42 AM
To:Wanucha, Dave
Subject:RE: R-2566BA Watauga River
Attachments:Watauga river mainstem photo 1 10-22-22.jpg; Watauga river mainstem photo 2
10-22-22.jpg; Watauga with causeway in background during 10-21-22 concrete
pour.JPG; cleanup crew inside of stagnant side channel 10-22-22.jpg; Watauga at
causeway during 10-21-22 concrete pour.JPG
Hey Dave,

Sorry for the earlier email, and for sending you a second one on the weekend. But, I wasn’t sure when I’d get a chance
to give you a longer/final summary, and wanted to let you know I was planning on sending you some more information,
in case you ended up with a complaint over the weekend. But hopefully you won’t get any complaints and won’t even
see this email until Monday!

When I got home Friday, a couple hours after our last correspondence, our project manager sent out an email with some
additional information. I was also able to speak to the prime contractor and now have a more complete understanding
of the issue. Luckily, the issue was short lived and centered around the project and did not appear to cause any issues
downstream. Also, the contractor was confident we can prevent a reoccurrence and be better prepared before the next
pour (which is several months away).

To recap the incident that occurred on the afternoon of Friday, 10-21-22, the drill pier they were filling with concrete
was encased (as you suspected), but there is a second larger cylinder that surrounds it and goes several feet into the
causeway. It acts as secondary containment. When they pump the internal cylinder with concrete they do so by putting
a long pipe down in the bottom of the cylinder, so as they pump, it displaces and forces water that has seeped in
underground from down in the cylinder up to the surface, and they pump that water to a silt bag. Everything must work
in harmony, because once they start the pour they can’t really stop. I guess if you only did half the pour and then had to
stop and start back later on, you would have a weak spot in the middle of the pier. So, you would half to somehow
excavate or drill out the part you poured and start over. The issue Friday was apparently from the pump not being able
to pump water out as fast as the concrete was being pumped in. The result of the pump not keeping up with the water
in the internal cylinder was that some water (mixed with silt and possibly some concrete) overflowed into the secondary
cylinder. They were able to continue pumping from it, but some of the water seeped through the bottom of it, through
the causeway, and entered the river.

All reports I’ve obtained suggests the material settled out and dissipated in a matter of minutes and did not extend far
downstream of the project - Laurel Fork flows in, just below the bridge, and I think this helped greatly to dilute the
issue. However, we definitely created a light brown/milky/turbid situation for a few minutes (see 10-21-22 photos). As
a result, and to play it safe, I got up Saturday morning and drove out to the project to check on things. The contractor
actually had a 6-7 person team on site to check on things and perform any needed cleanup. The river looked extremely
clear, and fish were visible as usual, and nothing looked distressed (see river photos from 10-22-22). You really couldn’t
tell anything had happened within the main channel. However, there is a side channel just below the causeway, and
with the Watauga River running very low right now (only 39 CFS, while the mean is 105 CFS), this side channel has very
little if any flow going through it. Since it is just below the causeway, and directly below our silt bag set up, it ended up
collecting a good amount of the material. I actually think this was a good thing, since it acted as a second
containment. However, I did notice a handful of small dead juvenile fish (1-2 inches long, and no trout) through the
reach. There were very easy to spot – very white and on the bottom, since dead a few hours, so I think if there were
more I would have seen them. All were essentially trapped in the side channel reach due to the low flows, and my
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assumption is the material that flowed into the channel from the river and our silt bag, in addition to the already
stagnant conditions, caused them to expire. It’s also possible that any concrete mixed with the turbid water that
entered the channel could have caused a micro ph issue. But, I saw no signs of distress or dead organisms in the main
channel, or downstream - I walked with waders 100 meters downstream around and in the river (it’s heavily posted
below this point so I did not go further). I feel confident if any fish were dead, I would have seen them. When I left, the
contractors staff were spraying the rocks off in the side channel with clean river water, and then pumping the wash
water back through a silt bag (see photo of cleanup crew, showing small side channel).

I’m confident any issues from the event are behind us, and we plan to all meet and ensure we are prepared for this
possible scenario in the future. This pour occurred at the upper end of the causeway where the river is the swiftest, so I
don’t think a turbidity curtain would have helped. However, the remaining pours are downstream in calmer water, so
we may look at a secondary dike system of jersey barriers rapped in plastic, outlined with a turbidity curtain, or
something like that. I’m going to talk to our roadside erosion staff and possibly some fellow DEO’s as well to get
advice. While I’m glad nothing negligent occurred, in that we had all typically BMP’s in place (causeway and pumping to
a silt bag), I guess you can never have to many containment/backup protection options.

Sorry for the lengthy email, but just wanted to make sure I gave you a solid summary for your files. Also, let me know if
you have any questions.

Thanks!

Kevin

Kevin Hining
Division 11 Environmental Supervisor
North Carolina Department of Transportation

828-386-7202 cell
[e-mail]

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

Email correspondence to and from this address is subject to the
North Carolina Public Records Law and may be disclosed to third parties.
_____________________________________________________________

From: Hining, Kevin J
Sent: Saturday, October 22, 2022 2:20 PM
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To: Wanucha, Dave <[e-mail]>
Subject: R-2566BA Watauga River

Hey Dave,

No major issues but will follow up with an email later this weekend about the issue we spoke about yesterday. Went
back to site today but want to get to house before emailing all the additional info.

Kevin Hining
Environmental Supervisor NCDOT Division 11
828-386-7202
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Email correspondence to and from this sender is subject to the N.C. Public Records Law and may be disclosed to third parties.
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