Effectiveness of Skimmers to Control Dewatering of Sediment Basins
Pennsylvannia State University
Basin Program Funds:
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.
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.
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
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