U-4906 Gum Branch Rd. Losses on 8_22

From:Gingrich, Sophia E
To:Lane, Stephen; Sprinkle, Hannah H; Shaver, Brad E CIV USARMY CESAW (US)
Cc:Farrell, Sean C; Westphal, Anneliese; Bullard, Jason M; Yarborough, Jerry W
Subject:U-4906 Gum Branch Rd. Losses on 8/22
Date:Tuesday, August 23, 2022 4:25:30 PM
Attachments:Site B_ loss.jpg
Site B_loss start.jpg
Site B_loss.jpg
Site B_manhole.jpg
Site B_wattle site.jpg
Site A.jpg
Site A_larger loss.jpg
Site A_manhole.jpg
Site A_silt fence.jpg
Site A_thin loss.jpg
Brad, Hannah, and Stephen,

I visited U-4906 and met with Mike Jones and Dave Monro today to get some more information on
the losses and their cleanup efforts. As Sean reported last night, there were two locations near Half
Moon Creek. Neither loss spilled into the CAMA AEC around the creek. Their rain gauges reported
2.5 inches, but they suspect there might have been more. The crossline pipe at approximately Sta.
81 + 00 -L1- has not been installed, so the heavy rain in the short period caused a backup in the
stormwater system resulting in water coming up out of the manhole covers, washing sediment away
and overwhelming the silt fence at approximately Sta. 81 + 00 -L1- RT and Sta. 79 + 75 -L1- RT. The
crossline installation will be completed by Friday which should prevent this situation from happening
again. In the meantime, they were putting fabric down around the manhole covers, filling in the
holes with 57 stone, and then placing rip rap on the slopes below. Straw was then being spread out
on the exposed shoulders and slopes. An exposed manhole can be seen in the Site B pictures and
one covered up as described can be seen in the Site A pictures. They were there cleaning up and
fixing the slopes while I was there.

Site A: Sta. 81 +00 -L1- RT. I did not get a measurement of the loss directly on the other side of the
silt fence because it had already been cleaned up. There was a pie shaped wedge of sediment with a
radius of about 33 feet that spread out in front of and slightly to the right of the silt fence. It was a
thin layer about 1 inch at its thickest. Just outside of the 33-foot radius in front of the silt fence,
there was a larger deposit. Its dimensions were 16 feet in length, 6 feet in width, and about 3 inches
at its thickest. More might be revealed once the water goes down some more. The water in the
wetlands up against this deposit was not turbid. To retrieve the sediment, they were using buckets
and shovels in the thicker areas and a rake in some of the thinner areas. They installed a wattle
break in the silt fence after it was repaired.

Site B: Sta. 79 + 75 -L1- RT. This loss was in an adjacent stream. The loss downstream was about 37
feet in length, 5 feet wide, and 6 inches thick at its thickest. Stones from an SDO had also washed
into the channel. They were going place a wattle across the channel at the furthest reach of the loss
to prevent sediment from moving further downstream during retrieval. The wattle will go at the
bottom edge of the picture labeled “Site B_wattle site.” It will be removed when the cleanup is
done. They were going to use buckets and shovels to retrieve the sediment and stones.

Sean and I will be visiting the project again tomorrow morning to check on the cleanup.

Thanks, and let us know if you have any questions.

Sophia Gingrich
Environmental Technician
Division 3
NCDOT – Division of Highways

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