Denville, N.J., is where Interstate 80, Route 46 and the Rockaway River intersect. If left unchecked, highway runoff, which includes deicing salt, motor fuel, oil, antifreeze and litter, would pollute the Rockaway River. A natural floodplain between the two highways normally would capture and retain these pollutants, until a high-water event like a sudden snowmelt or rainstorm raises the river level. Then the river would overrun the floodplain, dissolving the quiescent pollutants back into suspension and carrying them downstream, as well as threatening to flood a network of residential streets bordering the floodplain.
A pair of flap valves was installed in the 1970s, but they had deteriorated to the point that they were wholly ineffective at preventing backflow into the floodplain.
In 2013, the Denville Department of Public Works (DPW), in cooperation with the mayor of Denville, hired engineering firm Hatch Mott MacDonald to design a practical solution to replace the two existing flap valves. Hatch Mott MacDonald contacted Dave Heiner Associates concerning the storm water backflow prevention project in Denville, which recommended two Onyx Model DBS duckbill check valves, one 42 in. and one 48 in.
After presenting a detailed economic and engineering proposal that quantified the economic advantages and the simple, reliable and robust design of the valves, Denville DPW purchased them. The township hired PM Construction to complete the installation, and these valves now are diligently protecting the Rockaway River from toxic highway runoff as the river wends its way through Denville.