Effectiveness of Skimmers to Control Dewatering of Sediment Basins
Erie County, PA

Grantee: Pennsylvannia State University
Basin Program Funds: $10,000
Non-federal Funds: $14,647
Project Duration: 06/1997 - 08/1999
Status: complete

Problem Statement
Existing sediment basin spillways, primarily perforated risers, are not the most efficient or effective at reducing the amount of suspended particles released into the environment.

Dewatering mechanisms

Background
Under Federal Surface Mining Control and Reclamation Act and Pennsylvania Department of Environmental Protection regulations, mechanisms for controlling erosion from earth disturbance sites include sedimentation basins. Sedimentation basins capture and store eroded soil from effluent leaving a disturbed surface site before the water is discharged into the environment. The amount of sediment released is controlled by the basin's outlet structure, the most popular of which are perforated risers. Perforated risers withdraw water from the entire column, but the majority is removed from the lower layers where sediment concentration is highest. In order to increase the capture of sediment and reduce the amount of suspended silt and chemically active clays released to the environment, investigators tested the use of floating risers or skimmers to remove the highest quality of water from the basin.

Activities
With the support of Pennsylvania Department of Environmental Protection (PADEP), County Conservation Districts and engineering firms in each region, the project team selected three of four proposed sites to demonstrate the skimmer. The sites are located in PADEP designated regions; one is in Lehigh County (south-east region ), one in Centre County (north-central region), and one in Lebanon County (south-central region). The remaining site was located in Erie County (north-west region). As project personnel located demonstration sites they also scheduled opportunities for developers, engineers, regulators, Soil and Water Conservation District, and US Department of AgricultureľNatural Resources Conservation District personnel to learn more about the technology.

Four skimmers were ordered and installed at the demonstration sites. Demonstrations for interested personnel were scheduled and carried out. These demonstrations included a three-hour seminar followed by a field trip to one of the demonstration sites.

A skimmer in place

Results
This project demonstrated that, with the use of skimmers, sediment basins will save 34 pounds of soil per basin over the life of their construction. In addition, over 150 professionals (mostly engineers and conservation district personnel) have been reached during the grant period through seminars and field trips. It is projected that an additional 200 or more professionals will learn about the effectiveness of skimmers from this project.

Contact: Dr. A.R. Jarrett, (814) 865-5661

 

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