PANYNJ Pier Underfill
The Job
This pier underfill project is located in Hoboken, New Jersey, at a facility owned by the Port Authority of New York & New Jersey. The Authority leases the facility to a marine contractor, who is responsible for maintaining it. As part of this, the tenant had to install a new combiwall along roughly 2/3 the length of the pier, in total about 1100 linear feet. After the wall was in place, the contractor had to fill under the pier and behind the wall with tremie fill that would minimize lateral and axial loads.
CJGeo dry batch cellular grout plant onsite.
The Challenge
The project faced two primary hurdles. First, the team had to protect the new wall and the soft underlying soils from excessive weight. To solve this, CJGeo proposed using 75lb/cuft CJFill-Under Water. This specialized mix is dense enough to resist mixing with water during placement. However, it is only half as heavy as traditional flowable fill.
The second challenge involved monitoring. The voids reached nearly 20 feet behind the wall. To track the grout’s movement accurately, CJGeo recommended installing 4-inch monitoring casings via sonic drilling.
The Solution
CJGeo deployed a sonic drilling crew to the site. Over three shifts, the team drilled roughly 30 holes through mixed fill and the original wooden deck. We lined each hole with PVC casing to ensure clear monitoring during the pour.
Once the drilling was complete, CJGeo moved in a dry batch cellular concrete plant. We produced and placed approximately 6,000 cubic yards of CJFill-Under Water. This lightweight solution stabilized the pier without overstressing the new infrastructure.
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