Richmond County A Basin

Strickland, Bev
From:Paugh, Leilani Y
Sent:Friday, August 19, 2016 3:21 PM
To:Williams, Andrew E SAW; Wrenn, Brian L
Cc:King, Art C; Griffin, Randy W; Cail, William G
Subject:Richmond County A Basin
Attachments:A basin sketch Riser Modification with vegetation.pdf
Andy and Brian
Randy and I have reviewed the site with Division and Hydraulics. The stream is fairly stable where it enters the
site and then divides into several channels where the willows have established. The flow continues through
the cattails and then dumps into the ponded area at the riser. The vegetation has stabilized the sediment that
has accumulated in the upper end of the site but the sediment at the lower end is not vegetated.

The existing stream bed drops about 0.5 ft from where it enters the site to the beginning edge of the willows
and then another 2 feet down to the cattails. However, there is almost a 4 foot drop from the cattails to the
pipe invert at the riser. If we completely remove the riser, it may cause a head cut through the sediment at the
lower end of the site because of the difference in elevation.

The first figure in the attached file shows the site survey data. The second figure shows the proposed design.
We recommend cutting the riser down 2.5 feet from the top, bringing it to the same elevation as the cattail
area. Then a notch would be cut in the front of the riser at 0.5 ft deep and 2.5 ft wide to mimic the channel
dimensions.

This will reduce the ponded elevation and allow for sediment to fill in the basin near the riser, letting the
channel form its own path with vegetation establishing over time.

Please review and provide us your comments.
Thank you.

LeiLani Paugh
ICI/OSM Group Supervisor

919 707 6146
[e-mail]

NCDOT

Project Development & Environmental Analysis

1020 Birch Ridge Dr.

Raleigh, NC 27610

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From: Cail, William G
Sent: Friday, August 19, 2016 10:49 AM
To: Griffin, Randy W; Paugh, Leilani Y; Lindsey, Jerry L
Subject: Riser mod #2

Revised the riser view……per Jerry’s comment, showing appropriate 54” CMP view facing the riser.

Galen Cail
Maintenance-Operations Support

Hydraulics Unit

Department of Transportation

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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