Opportunity
Overpeck Creek, a manmade freshwater creek in northern New Jersey, has become a prized location for competitive rowing teams. Protected from tides and powerboats, the creek is wide enough for three lanes of boats and long enough for collegiate races. Compared to the Passaic River and the lower Hudson, it is also clean. In April 2012, the creek was the site of the Blackwell Cup competition between crews from Columbia, Yale, and the University of Pennsylvania.
Overpeck Creek was not always so pristine. According to the New York Times, it was once “a murky soup of reeking refuse,” fit only for “illegal dumping and trapping muskrat.” As part of a seven-year, $100 million effort by Bergen County, the creek was cleaned up and the nearby landfill turned into Overpeck Park.
During wet weather, sewage overflowed from the 27,000-foot Overpeck Valley trunk sewer, which carries wastewater from Englewood to a new treatment plant in Little Ferry. Despite the construction of several overflow chambers, the system was sometimes overwhelmed. The New Jersey Department of Environmental Protection received a court order requiring the Bergen County Utilities Authority to eliminate Overflow 006, which discharges into Overpeck Creek.
Solution
Determining that a parallel relief sewer was the most cost-effective method to prevent the overflow, the Bergen County Utilities Authority selected Mott MacDonald in 2004 to provide the engineering design, permitting, and construction management for the project.
This design called for 15,000 feet of 72-inch sewer, 10,300 feet of 66-inch sewer, and 2,700 feet of 42-inch sewer. The new sewer will be constructed parallel to the existing 60-inch trunk sewer. Interconnections at eight locations will distribute flow between the new and existing conduits. Either pipeline can be taken out of service for maintenance and inspection.
Because of tremendous growth and development in the area, construction of the new sewer had to cope with many nearby structures. Trenchless technology, including microtunneling, was used to cross a major railroad yard, the New Jersey Turnpike, and State Highway Route 46, where deep excavation and dewatering would disrupt commerce and utilities.
Outcome
The project was completed on schedule and with minimal disruption. It received an honorable mention in the December 2009 issue of Trenchless Technology magazine.
Philip W. Lloyd, Zhenqi Cai, and Glenn Duyvestyn of Mott MacDonald used the project as the subject of their paper “Microtunneling Challenges: Crossing Under Major Railroad and Highways in Very Soft Glacial Soils — The Evolution of a Ground Treatment Assessment Process.”
Thanks to the Overpeck Valley relief sewer, Overpeck Park will remain a safe and attractive recreation spot, and Overpeck Creek a valued location for competitive rowing.