Pump Station – Atlantic City, NJ

When the Army Core of Engineers and a reputable New Jersey-based construction company sought help excavating an 18′ x 23′ x 30′  cofferdam for the installation of a municipal pump station, they consulted Hydro Spy LLC, a Texas-based vacuum excavation specialty contractor. Hydro Spy outlined a qualified plan of action involving coordination with other contractors to excavate more than 480 cubic yards of soil over several days using a GapVax hydro excavator.

The general contractor faced two challenges. The first challenge was finding a way to perform a 30 ft vertical excavation in a 23′ x 18′ box with a track-hoe (hint: not gonna happen). The second challenge was finding a way to remove excess water from the soil prior to the excavation process.

Sheets piles were driven into the ground to form a 23′ x18′ box, then wet-wells were installed around the box to manage all ground water. Afterwards, Hydro Spy excavated the pit using an industrial truck-mounted vacuum loader in conjunction with controlled water pressure to break up the soil.

It took Hydro Spy less than 2 days to reach an initial target depth of 20 ft, as load after load of beach sand and water were sucked into a 15 yard debris tank and hauled a mile away where it was dumped in piles for reuse.

After reaching the initial target depth, the excavation process was interrupted for two days to allow the general contractor to install wales and braces around the interior of the sheet piles. Afterwards, Hydro Spy resumed excavating, finishing the entire cofferdam pit in a total of 3 1/2 days.

Craft Notes: Excavating a cofferdam or pit of these dimensions poses certain risks that must be mitigated prior to the start of the project. First, only highly trained craftsman should be involved in this type of excavation procedure. Minimum training includes 1 year hydro excavator experience, Basic Plus, Confined Space and Excavation Safety. Personnel needed to safely and compliantly hydro excavate a cofferdam  includes 1 operator and 2 technicians or 1 operator, 1 technician and 1 supervisor.


Safety Elements: Confined Space Attendant, full-body harness with lanyard and lifeline, air & gas monitor.

Project Scope: 18' x 23' x 30' Coffer Dam
HydroVac Application: Vacuum Excavation
HydroVacs: 1
Industry: Civil Construction
Location: Atlantic City, NJ