Headwall Scour Protection

Project Overview The NCDOT replaced a double barrel culvert with a larger single barrel culvert under Ivey Road

Project Overview

The NCDOT replaced a double barrel culvert with a larger single barrel culvert under Ivey Road about a half mile east of Route 87 in Graham. The old culvert experienced scour left of the culvert inlet and NCDOT wanted ensure that scour didn’t occur at the face of the new headwall in the same location. Initially, it was the NCDOT’s intention to install at the inlet location only.

However, after a rain storm less than two weeks after the initial installation, scour at the end of the SW wing wall beyond the culvert outlet occurred and additional scour protection was installed using Combat Concrete (CC) GCCM.

Solution

NCDOT chose to install CC GCCM at a location that had been a problem in the past. Where the previous scour hole existed, Combat Concrete GCCM matting would be attached to an angle that was attached to the headwall. The construction material matting was attached to the headwall and the edges buried. The buried toe was covered with riprap. While not needed for stability, soil anchors were placed as a demonstration of how CC GCCM, an erosion control measure, would dovetail with a stabilization technique. The GCCM was hydrated with stream water using a small pump. All this work was completed within a couple hours.

The area around Graham received between 1.5 and 3 inches of rain, causing flooding, high velocity water and turbulence around the inlet and outlet of the new culvert, causing scour at the end of the SW wing wall.

Because the GCCM construction material remained in place and performed well through the weather event, it was decided to use GCCM to repair the scour that occurred at the end of the SW wing wall. After the slope was reshaped, GCCM was placed at the end of the wing wall with 10 soil anchors.

Photo: Milliken

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