Former Petroleum Terminal Soil Stabilization

The site was located on Duck Island, along the southwestern border of Hamilton Township in Mercer County, New Jersey. This area contains several active petroleum terminals, a former landfill, and a power plant. It is bordered by the Delaware River to the southwest and an artificial wetland to the southeast. The site had been used for industrial purposes since 1931 and eventually became part of ExxonMobil’s operations.
 
A significant incident on January 3, 1974, caused the release of approximately 600,000 gallons of Number 2 Fuel Oil at the site. Of this, about 276,000 gallons were recovered, but an unknown quantity of oil was discharged into the Delaware River. This spill left a substantial amount of residual fuel oil in the saturated soils, contributing to a groundwater contamination plume and leading to the necessity for soil and groundwater remediation.
 
The challenge of remediating this legacy industrial site was considerable. It involved addressing the residual free product in the saturated soils to prevent further contamination of the groundwater. The environmental and soil remediation efforts were crucial to mitigate ongoing pollution, protect the surrounding ecosystems, and ensure the health and safety of the local community.

To remediate the legacy industrial site effectively, we began by mobilizing all personnel and equipment necessary for the In-Situ Stabilization (ISS) operations. This included the installation and setup of a grout plant and associated equipment to facilitate the process.

We coordinated the supply and management of Portland cement and granulated ground blast furnace slag (GGBFS), which were critical for generating the grout required for ISS implementation. These materials were vital for achieving the stabilization needed for effective environmental and soil remediation. The mix design used for ISS consisted of 6% blast furnace slag cement and 4% Portland cement by dry soil weight. We calculated the weight of slag and cement using the provided dry soil weight of 105 pounds per cubic foot.

ISS grout batching was performed using a Forgen-owned Scheltzke MS 700 fully automated grout mixing plant. The operator programmed the plant to deliver the correct amount of water, cement, and slag according to the prescribed mix design. The appropriate amount of water was then metered into the colloidal mixing tank, and dry reagent was metered into the batch tank using two separate screw conveyors to deliver the specified weight of slag and cement.

Once the grout was initially mixed, it was transferred to the agitator storage tank with a capacity of approximately 750 gallons. Grout from the agitator storage tank was pumped through piping to the active ISS work area using the batch plant pumping system, which was operated by the batch plant operator.

The ISS soil mixing was generally performed in cell sizes of 525 square feet, typically measuring 15 feet wide by 35 feet long. Due to depth variations, the daily production rate varied, with an approximate average of 890 cubic yards per day. An excavator was used to homogenize the grout and soil over the entire depth of the treatment cell. The soil and grout were mixed until the material appeared adequately homogenized. Once a cell was considered visually homogeneous, the measurement of the ISS treatment depth was determined by survey.

At a rate of one sample per 500 cubic yards, ISS field samples were collected from the treated soil within one hour of mixing completion while the ISS-treated material was still wet and pliable. Each wet grab sample was obtained at the location and depth requested by our client using the excavator bucket. Swell material exceeding the maximum elevation of ISS treated material, set at 6 feet below the original grade, was excavated and stockpiled for load-out and off-site disposal by others.

We carefully managed the swell generated during ISS operations, ensuring the removal of material only as necessary to support the advancement of the ISS process. Surveys were conducted to ensure precision in the ISS work. We also performed comprehensive quality control measures, including sample collection and analysis to meet performance criteria. Progress reports, submittals, and Contract Records Documents were prepared and reviewed to confirm the successful completion of the ISS operations.

Upon completion, we maintained rigorous site housekeeping standards and then demobilized all equipment and personnel.

All samples met the performance criteria of greater than 50 psi unconfined compressive strength (UCS) and less than 1×10-6 cm/s hydraulic conductivity. Our geotechnical construction approach ensured the site was effectively remediated and prepared for future use, addressing both environmental and safety concerns. The environmental remediation solution we provided for this legacy industrial site not only mitigated ongoing pollution but also protected the surrounding ecosystems and ensured the health and safety of the local community.

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