The T-VSSI project team constructed two Upland Stormwater Wet Ponds at the Pennypack Ecological Restoration Trust (PERT) within the Pennypack Creek Watershed. The stormwater wet ponds overflow into an existing upland wetland and shallow pond that are adjacent to Paper Mill Road. The researchers selected this location on the PERT property because it is at a topographic low point, receiving stormwater runoff from an area of approximately 54 acres. Of those 54 acres, less than 5% are impervious and the remainder is either forest or mowed grass pasture.
In July 2006, the T-VSSI project team constructed two upland stormwater wet ponds that overflow into an existing upland wetland and shallow pond, which are adjacent to Paper Mill Road on the property of the Pennypack Ecological Restoration Trust (PERT). The stormwater wet ponds are designed to capture non-point stormwater runoff from a 54-acre drainage area of grassy meadow and forest. The project site is also designed to retain stormwater; facilitate the evapotranspiration of stormwater; develop a functional macroinvertebrate community in the new wet ponds; achieve an upland wetland structure and function; and assess plant nutrient uptake through controlled experiment.
As stormwater runoff exceeds the storage capacity of the larger wet pond, it will overflow into the second stormwater wet pond, which has a low-water elevation that matches the existing pond, and during high-water events it will overflow into the existing pond over a vegetated berm that is about six inches high. There is little stormwater storage capacity in the lower wet pond. The existing shallow pond, drains into an existing drainage ditch and then into a stormwater pipe that eventually flows to Terwood Run, an important tributary to Pennypack Creek. Through retention and evapotranspiration, this project site is designed to reduce non-point source runoff within the upper Pennypack Creek watershed.
In August 2006, the researchers developed a planting plan and installed wetland species, shrubs, and trees. The intent was to create an upland wetland habitat.
Planting Diagram (pdf)
The goals of the design of the upland stormwater wet ponds are to:
- Capture non-point source stormwater
- Retain stormwater
- Evapotranspirate stormwater
- Capture sediment
- Achieve upland wetland structure and function