Project Announcement: Forbidden Drive Streambank Stabilization Project Gets Underway

Current Projects // June 12, 2019

Friends of the Wissahickon’s (FOW) much anticipated stabilization of three major streambank collapse sites along Forbidden Drive is set to begin the week of June 17, with construction expected to be completed by the end of October. The specific streambank locations, which have continued to erode since the initial collapses, are: the Valley Green site (approximately 1,000 feet downstream from Valley Green Inn); the Mt. Airy Ave. site (near the Mt. Airy Avenue pedestrian bridge); and the Kitchens Lane site (immediately downstream from the Kitchen’s Lane Bridge).

The overall restoration project consists of three integrated components:
1. stabilizing the bank toe (especially susceptible to water erosion because of its location between the regular and low water levels), with large rock;
2. reforming and stabilizing the bank above the toe using vegetated soil lifts (similar to terraces);
3. reforesting the upper bank slopes adjacent to Forbidden Drive with a combination of native trees, shrubs, and herbaceous seeding.

This project will also include removing trees, trenching and installing boulder walls, and grading slopes. The Forbidden Drive Streambank Stabilization Project will be a vital contribution to the resiliency of Wissahickon Valley Park’s infrastructure and overall water quality

To tackle this complex work, FOW has contracted an ecologically-driven restoration and land-use solutions team. RiverLogics Solutions, based in Wellsville, PA, is leading the project work to install rock-toe stabilization. RiverLogics is coordinating with Applied Ecological Services (AES) from Wisconsin for the vegetated soil lifts on the streambanks. This summer, AES will heavily seed the soil lifts and upper banks, returning in November-December to install dormant live stakes (woody cuttings with the branches removed, often used to stabilize streambanks) within the soil lifts and plant potted trees and shrubs on the upper banks.

Caution Ahead
Construction will begin at the most northern site, just downstream from Valley Green Inn. During construction at each site, Forbidden Drive will be narrowed to about 12 feet to allow for temporary fencing of the work zone to contain materials and machines and maintain adequate passage for emergency vehicles. The fencing will remain in place until the construction at this site is completed, then it will be removed and relocated when the crew moves downstream to the next project site.
Throughout the construction, heavy equipment will be periodically moving along Forbidden Drive carrying materials and equipment to the project site. All vehicles will follow the 7mph speed limit on Forbidden Drive, clearly marked with safety flagging, and use audible warning signals.

Stay alert, safety first! When you’re in the park near the construction sites, don’t assume that equipment operators see you. At all times, give heavy equipment the right of way, slow your pace and keep children, dogs and horses under control and at a safe distance. When approaching work locations, remove audio earbuds/headphones. Under no circumstances should any park user enter work zones. During the construction period, please stay out of the work zones and heed safety signage at all times – even when crews are not working.