Site Drainage, Philadelphia, PA

Case Study 

Application	Site Drainage	Job owner	Children's Hospital of Philadelphia (CHOP)
Location	Philadelphia, PA	Engineer	Terry Brennan, DPW Director
Product	Mirafi® G200N	Contractor	EDA
Quantity	52,000 sq ft	Date of Installation (m/y)	March 2012

THE CHALLENGE

The Children’s Hospital of Philadelphia (CHOP) is one of largest and oldest children’s hospitals in the world and is ranked as the best children’s hospital in the United States. As part of a major expansion, CHOP’s newest facility, the Ambulatory Care Center, was being constructed at the west side of Schuylkill River at 34th St. and Civic Center Blvd. This is the old site of the Philadelphia Civic Center. When completed, the expansion will include a 5 story below grade parking garage with an ambulatory care center with outpatient services. Because the new facility was being built within the footprint of the old Civic Center, the challenge was to maximize the available space while accounting for water seepage due to the high water table of the adjacent Schuylkill River.

THE DESIGN

In order to accommodate the parking garage, a tied back wall was designed using steel H-piles and wood lagging to hold back the soil. The steel piles were spaced vertically at approximately 8’ centers with wood lagging placed horizontally in between the piles. At lower depths the excavating contractor (EDA) encountered ledge. In order to create a smooth surface to attach TenCate Mirafi® G200N drainage composite, shotcrete was placed against the ledge.

THE CONSTRUCTION

Once the steel piles were driven and the shotcrete was placed, EDA began installing Mirafi® G200N drainage composite. Starting at the bottom, with one man on the ground and two men on a scissor lift, Mirafi® G200N drainage composite was attached to the shotcrete and wood lagging using a pneumatic nail gun, placing concrete nails at 3’ centers. Adjacent drainage panels were overlapped several inches. After the drainage composite was attached, a rebar mat approximately 3” thick was placed over Mirafi® G200N. Then, the whole interior wall received a layer of shotcrete to create the interior walls of the parking garage.

THE PERFORMANCE

By incorporating Mirafi® G200N drainage composite, considerable amounts of space and construction time were saved compared to typical stone chimney drains. EDA Contractors was very pleased with the ease of installation and labor. The installation was flawless and it allowed EDA to finish their contract earlier than originally anticipated.