In 2005, Montgomery County Conservation District was awarded Growing Greener funding to implement a stormwater best management practices demonstration site on the headwaters to the Little Neshaminy Creek in Montgomery Township, a suburban landscape in Montgomery County with high impervious cover. Impervious surfaces are mainly artificial structures such as pavements (roads, sidewalks, driveways and parking lots) that are covered by impenetrable materials like asphalt, concrete, brick, and stone, as well as rooftops of commercial and residential buildings. When stormwater washes over these impervious surfaces, it picks up pollutants brings them to local waterways, negatively harming wildlife, plants, and people.
The Growing Greener funding was awarded to retrofit a stormwater basin at the Mary Mother of Redeemer Church and School, a 30 acre facility with many existing natural features including wetlands, a pond, and a headwater stream tributary to the Little Neshaminy Creek.
The stormwater retrofit involved removing a concrete low flow channel, modifying the outlet structure to provide extended detention, installing a sediment forebay to filter stormwater runoff, and naturalizing the basin. After the low flow channel was removed, a water quality berm was installed to maximize the flow path in the basin. The elevated berm directed stormwater through the basin, allowing it to meander within the basin before reaching the outlet structure. The sediment forebay is a holding area where the stormwater enters the basin lined with larger rock which filters sediment and particulates from the stormwater as it enters the basin. At the outlet structure, the existing orifice was covered with a steel plate, and a new smaller orifice was installed one foot higher. This provides extended detention and enabled the basin to support wetland vegetation.
Following completion of the basin modifications, students and parishioners of the Church and School planted native vegetation in the basin.
In addition to retrofitting the stormwater basin, the Growing Greener grant helped to leverage additional funding for the project. A TreeVitalize Watershed grant was awarded to plant 203 trees and 342 shrubs to increase canopy cover, create wildlife habitat, and buffer the headwaters stream. The grant also funded 150 live stakes to enhance biodiversity in the wetlands.
Rohm and Haas, a local company, made a donation to help to purchase monitoring equipment for the students to study water quality in the stream and wetlands, and to monitor the quality of the runoff at the inflow and outflow of the stormwater basin. The conservation district applied for a Consortium for Scientific Assistance to Watersheds (C-SAW) grant from Stroud Water Research Center to assist with establishing lesson plans and instructing the teachers on how to use the monitoring equipment.
Now, almost two years after the project was completed, the students and parishioners still continue to embrace the project and it’s environmental benefits. The Church’s Ecology Council maintains the best management practices, and the riparian buffer plantings. There is a walking path through the buffer that allows users to enjoy the solitude of this newly created habitat. The project was awarded the 2009 Pennsylvania Horticultural Society’s Community Greening award.