by Lou Mancinelli
During the past two weeks, a hurricane and torrential rainfalls have drenched the area, causing flooding and road closings from I-76 to the Kelly and Lincoln drives. In the Wissahickon, surging waters washed out trails, downed trees and carried dirt and sediment into its streams.
But even putting aside recent storms, the Wissahickon floods dozens of times each year, and maintaining the pedigree of the streams and trails in the park is a constant process, according to Maura McCarthy, executive director of Friends of the Wissahickon (FOW).
To deal with the problem, the Philadelphia Water Department (PWD) is undertaking major stream restoration projects at Bells Mill Run and Wises Mill Run, feeder streams of the Wissahickon that run along Bells Mill and Wises Mill roads.
The goal of the projects, according to Joanne Dahme, PWD general manager of public affairs, is to restore and protect the ecological integrity of the streams, which are challenged by urban storm water runoff. The projects, which are slated to be completed within one year, is part of a citywide PWD effort to restore and protect streams and drinking water, from Cobbs to Tacony creeks and elsewhere.
In addition to the PWD project at Bells Mill Road, east of Ridge Avenue to Forbidden Drive, and Wises Mill Run, the Philadelphia Parks and Recreation Department, FOW and other city agencies are working on stream and gulley restoration at various locations throughout the park, according to McCarthy.
At Bells Mill Road, storm water has eroded several stream banks. The approximately $2 million PWD project will redesign, strengthen and re-landscape the banks to prevent further erosion, as well as direct storm water from the street so that it flows in a more efficient and less invasive current to the streams, according to Joe Trafka, a PWD construction engineer.
That project began in June and is about 50 percent finished. Trafka said PWD plans to finish the stream-work segment of the job before winter.
The Wise’s Mill Run project includes work at four different locations, according to Trafka. They are Wise Mill Road, Cathedral Run, from Henry Avenue to the creek, Summit Avenue and off Siefert Road.
The approximately $1.4 million project includes installing storm water management with the goal of taking storm water from Wises Mill Road and Cathedral Run, and channeling it to a diversion structure, or wetland. There exists already one wetland at Cathedral Run and Wises Mill Road. The PWD will build an additional almost three-acre wetland at Wises Mill, he said.
“The overall goal is to reduce the amount of sediment being deposited into the streams and rivers,” Trafka said. “If you can eliminate erosion and channel erosion, you can eliminate sediment.”
In 2007, issues reported in the PWD Wissahickon Creek Watershed Comprehensive Characterization Report, included water quality impairments (bacteria and nutrients, and pH fluctuations), invasive species, especially Japanese knotweed, sedimentation in streambeds – especially in important habitat areas of runs and pools – loss of headwater wetland areas and excessive algae growth.
The current projects are the PWD’s response to these issues. The current FOW and Parks and Recreation initiatives also will work to mitigate those issues and preserve the future longevity of the park.
According to McCarthy, members of the FOW received $750,000 from a federal $9 million judgment against North Wales pharmaceutical giant Merck Inc. In June 2006, a Merck sewage plant spill dumped 55,000 gallons of sewage water and traces of cyanide into the Wissahickon, violating the Clean Water Act.
That money will be used for the FOW and Parks and Recreation projects to reduce the volume and flow of water in the park, so when it rains, less street dirt is carried into the streams. The design phase of the project began in 2009, McCarthy said.
“It’s a complicated effort the Philadelphia Water Department has been managing,” she said. “Instead of spending the money on gray infrastructure, they are spending the money on improving the green space and quality of water. We are excited to be part of such an innovative project.”
Gray infrastructure refers to impervious surfaces like concrete trails. By building and utilizing green infrastructure, McCarthy noted, the capability and functionality of natural resources can be maximized.
According to McCarthy, the Environmental Protection Agency sets the Total Maximum Daily Loads (TMDL) for sediments and nutrients in the Wissahickon and watersheds around the nation. TMDL standards are designed to protect the integrity of the quality of water in streams and to protect drinking water.
The restoration projects are connected and cater to TMDL requirements. Drinking water for the Northwest is cleaned at the Queen Lane Intake Station, where the Wissahickon Creek meets the mouth of the Schuylkill River, McCarthy said.
FOW projects in the park include gulley restoration at Historic Rittenhouse Town, the Kitchens Lane Gulley (which was completed this summer), and the Bluebell Meadow Pavilion. Parks and Recreation projects include an Andorra Meadow expansion, Houston Meadow reclamation and a gulley restoration at Walnut Lane Golf Course, according to the FOW website.
“When the Friends of the Wissahickon picks project sites, we try to kill two birds with one stone,” McCarthy said.
That means selecting sites with storm water and waterway applications, finding weak or eroded trails, closing them and rebuilding them, she explained.