Phase I of the Green Stormwater Infrastructure project in Andorra is set to begin construction in March and be completed by early June. This unique project, funded by the Pennsylvania Department of Environmental Protection, takes a watershed approach to mitigating damage from uncontrolled surface stormwater flows originating from Northwestern Avenue and the adjacent minimally vegetated parkland. A series of features designed to intercept, treat, convey and infiltrate stormwater will greatly decrease sediment carried into the Wissahickon Creek, while greatly increasing the quality of the day-use area of the Wissahickon Environmental Center and adjacent trails.

When the work is completed, park visitors can expect to see an enlarged and re-vegetated basin at the upper parking lot off Northwestern Avenue, with a series of vegetated rock cascades leading from the basin down the hill through the forested canopy. At the Wissahickon Environmental Center day-use area, a vegetated rain garden and swale will lead to the existing wetland located downhill and along the drive from the WEC. This lower reach of the watershed will be addressed later as Phase II of the project.

The Wissahickon Environment Center, Lower Parking Lot, the “Tree House,” and public restrooms will be open during regular hours throughout the construction period. The access road from Forbidden Drive will also be open. 

The environmental engineering firm A.D. Marble, based in King of Prussia, has guided the project from concept to final design, and Lancaster-based Flyway Excavating is the contractor on site turning the 2-D drawings into 3-D reality.

Safety During Construction

Friends of the Wissahickon consulted with Philadelphia Parks and Recreation and Natural Lands Restoration staff to help ensure public safety and minimize impacts on park users during construction. With that in mind, we ask visitors to the Andorra Natural Area during the construction period to please stay out of the work zone and heed safety signage at all times, even if no work crew is present.

• The work zone itself will be entirely closed to the public from early March to early June.
• The Upper Parking Lot will be closed during the entire project since it will be the main staging area and will be used for material stockpiles and equipment. 
• The Bike Bypass will be closed during construction. 
• Northwestern Avenue at the Upper Parking Lot will be closed to all vehicle traffic for a few days during the construction period. 
• The Red Forest Loop and Connector Trail will not be impacted except for a few days based on the construction schedule. From the WEC, this is the most direct route to Andorra Meadow.

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