Restoring Navigation and Protecting Wetlands
Challenge
Since the 1970s, the Borough of Avalon has used the Graven’s Island Confined Disposal Facility (CDF) to dispose of material dredged from channels, harbors, and boat slips in the back bays.
However, upon completion of a dredging project in 2009, the CDF was filled to capacity and unable to accept additional dredged material. A suitable site had to be found for up to 180,000 cubic yards of material that remained to be removed from the back bay waterways.
Solution
An alternatives analysis conducted by HMM concluded that the most viable alternative was to empty the Graven’s Island CDF. This presented a challenge since the CDF is located approximately one-half mile from the nearest roadway.
After considering various methods of removal, HMM recommended the construction of a haul road from Avalon Boulevard to the CDF. HMM completed the design and prepared plans and specifications for constructing a “floating” road to the CDF, excavating and removing the existing dredged materials, and hauling the materials to a processing facility.
The haul road designed by HMM represents a modern adaptation of a technology used by the famous 19th century British railroad engineer George Stephenson, who used bound heather and branches as a bed for the stone railroad base across a peat bog.
Benefits
The project proceeded on schedule and the CDF was emptied by November 2014. The emptying of the CDF allowed the immediate dredging of critically shoaled waterways in the Borough’s back bays, improving recreational and commercial boating safety and navigability by emergency vessels.
The haul road alignment and cross section were designed to reduce environmental disturbance. About 144,000 cubic yards of material, traditionally considered “spoils,” was sent to a materials processing facility for blending and beneficial reuse.
Avalon’s decision to empty and reuse its confined disposal facility minimized environmental impact and made the site available to Middle Township and the New Jersey Department of Transportation for their own dredging projects. The township and NJDOT contributed $1.5 million to the cost of emptying the CDF.
