Featured Project: Baird Creek Sediment and Erosion Control Project

Grantee: Glacierland RC & D
State: WI
Basin Program Funds: $17,033
Project Duration: 18 months
Project Type: Technical
Contact Information: office@glacierlandrcd.org, (920) 465-3006

There was a severely eroded embankment within the Baird Creek Parkway near the rear of 3065 Sitka Street in the City of Green Bay. A private storm sewer system discharges near the embankment. The overland flow concentrated as it descended the embankment, creating an eroded channel to the base of the embankment.

Embankment before construction

Activity
To remedy the problem, the City of Green Bay proposed construction of a series of storm sewer pipes and drop manholes into the embankment to safely transport the water to the base of the slope. The privately owned storm sewer system was connected directly to the proposed storm sewer, and a depression with an inlet will be constructed near the top of the embankment at this location to capture overland flow through this area.

The existing slope around the eroded area is near a 3:1. To construct a storm sewer beneath this slope would require a slope of over 20%, which would cause the water within the storm sewer pipe to move so quickly, that the water would cause significant erosion at the base of the slope, possibly compromising the toe of the slope that may cause a slope failure.

The use of drop manholes allowed the storm sewer to be built at a more reasonable slope of 3%, with several sudden drops to account for the significant change in elevation along the slope. Use of flatter pipe will result in lower flow velocities, and drops will dissipate the energy of the water. A discharge structure was constructed at the end of the pipe, before the water is released onto natural ground.

Embankment before and after construction. Photos courtesy of Glacierland R C & D

Results to date
After the storm sewer system was constructed, the embankment was restored to a 3:1 slope, similar to the slopes adjacent to the eroded area. A buried multiple drop conveyance system allowed for a more natural surface look to blend into the surrounding area. The concrete manholes and PVC pipe used on this project have an estimated service life of 50 years.

Native plants and seeds were used after construction. Since the project is on property owned by the City of Green Bay, the City Department of Public Works will maintain the project site.

The grantee would consider installing this BMP again if it had a site with similar characteristics.

Embankment after construction