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New! Graphical explanation of retrofit project
The project is a series of efforts designed to correct poorly designed stormwater management facilities located in the Township open space.Over the years the project has evolved as we learn more about the site and “best management practices.” In general, the projects address stormwater runoff that has been identified as a major cause of water quality problems in the nearby Pine Run.
To date the major element of the project has been the construction of the stormwater infiltration system. Plumstead Township received a Growing Greener grant for the Pennsylvania Department of Environmental Protection (PA DEP) in 2002 to fund this first phase.
The original proposal included several best management practices: infiltration trenches; wet seed planting in dry basins; and wetlands creation at the wet retention basin.During the early stage of the grant program it was determined that soils on site were better suited to a series of infiltration trenches. Construction of the wetland at the wet basin was postponed due to the estimated high cost and work to additional basins was scaled down. The final project included placing trenches below the dry basin where soil conditions allowed for maximum recharge. A signboard describing the trench program was also provided and the upper dry basin was seeded with wildflowers and its concrete flow channel removed to slow runoff.
Other steps taken over the past few years to reduce stormwater runoff and help reducepollution entering the basin were much easier to implement. These small steps included the implementation of a “no mow” policy in the surrounding meadow to deter the large goose problem and slow water runoff, and the planting of native trees and shrubs.
During the implementation of the infiltration project, the PA DEP encouraged the Township to apply for the wetland creation program.The implementation of a wetland would greatly increase water quality and along with infiltration trenches provide a demonstration of the various best management techniques.In 2005, the Township was awarded a grant to develop the design of a wetland and to develop construction plans and costs. The design phase will be completed in February 2006. A construction phase is expected to begin in late 2006.
Why create a wetland?
The project, part of a grant from the US Environmental Protection Agency (EPA) in conjunction with the PA Department of Environmental Protection, is designed to reduce high levels of pollutants in the existing stormwater retention facility from entering the nearby Pine Run. This water quality mitigation project is critical to reduce pollutants in the Pine Run which has been listed by the state as an “impaired” stream.In addition, the wet basin is currently highly eutrophic (depleted of oxygen) and undergoes seasonal algae blooms.
The main cause for poor water quality entering the basin and Pine Run is runoff from the existing development. High levels of nutrients from lawn fertilizers have been identified as the major pollutants. These pollutants are attached to sediment that drop to the basin’s floor causing periodic algae blooms.In addition, the open body of water attracts a large number of geese, whose dropping further add to poor water quality and cause other health risks. Wetlands are ideal for filtering these pollutants—removing the nutrients and cleaning the water before it leaves the basin. An added benefit is that created wetlands also provide improved wildlife habitat and are much more aesthetically pleasing and diverse than the retention basin.
What does the wetland creation project entail?
The wetland creation project includes two phases: design and construction.The design project included a detailed study and analysis of the wet basin. A survey of the basin floor was completed last fall and an environmental engineer and landscape architect were hired to use this data to formulate concept plans. A public meeting was held on January 17, 2006 to present their findings. A final design was selected that provides maximum water quality, eliminates future algae blooms, and provides the most aesthetically pleasing landscape. Construction costs and detailed plant lists will be developed based on the final design selection.
Construction of the wetlands is planned for late 2006/2007 and will include 1.7 acres of wetland area in what is now a highly degraded stormwater retention basin. There will be shallow open water areas and water flow pathways through pockets of wetland areas. The design will include two deeper open water areas, a sediment forebay and a micropool.The sediment forebay will be installed at the inlet headwalls to slow runoff and drop out sediment and pollutants before stormwater is conveyed through the wetland.The micropool will be installed at the outlet structure and will serve to settle out particulates, while cooling the water before it is discharge into the nearby Pine Run. The wetland will also include a berm to prevent short-circuited stormwater flow through the wetland. Stormwater travel time and pollutant removal is maximized in this design.In addition to its water quality functions, the design provides the opportunity for multiple habitat and landforms types.
Will there be disruption to Grandview Drive during construction?
Traffic into and out of the development will not be disrupted.The basin headwall will be lowered by three feet and connecting piping will be installed to an existing curb inlet on the basin side of Grandview Drive. Work will not cross the roadway.
How can I learn more?
In the near future an educational board and detailed plan will be provided at the kiosk along Grandview Drive. The wetland concept plan and other iformation can also be viewed at the Township Administrative Office. You may also want to view the Pine Run Watershed report prepared in 2004 to learn more about the Pine Run and what you can do to reduce stormwater runoff and pollution.
Related Documents:
Pine Run Watershed Brochure |
