Formatted Title
Rapid Remediation of Historic Oil Terminal/Refinery for Redevelopment
Background/Objectives
A large industrial redevelopment client planned to develop a historic 81-acre portion a bulk storage petroleum hydrocarbon terminal/refinery in Bayonne, New Jersey, into a ~1 million square foot (ft2) logistics warehouse. Extensive due diligence was required to fully characterize and define the environmental liability and remedial scope since all environmental liability would be transferred through the acquisition with the plan to complete remediation in approximately 1.5 years. The path forward to develop the site under New Jersey Department of Environmental Protection (NJDEP) protocols was to address six large light non-aqueous phase liquid (LNAPL) plumes, maintain existing hexavalent chromium caps, remediate polychlorinated biphenyls (PCBs) in accordance with Toxic Substance Control Act (TSCA), cap the entire site with ~500,000 cubic yard (CY) of imported clean fill to raise the site above 100 year floodplain levels. Environmental remediation was to occur within an accelerated schedule and maintain other ongoing property redevelopment tasks (i.e., civil, ground improvement, building construction activities).
Approach/Activities
All environmental liabilities were addressed simultaneously with the primary focus on addressing free product via excavations combined with in situ stabilization (ISS). Due diligence identified approximately 200,000 cubic yards (CY) of impacted soil to remediate and eliminate free product. Impacted soil included a large smear zone, shallow water table (~6 ft below ground surface [bgs]), and relatively deep impacts (~20 ft bgs) which made deep excavation with dewatering suboptimal. ISS was identified as a NJDEP approved method to stabilize free product and has provided many advantages over extensive excavation including lower costs, accelerated production, reduced material handling and disposal, onsite soil treatment, and geotechnical ground improvement to promote property redevelopment. Upfront bench testing and a conservative ISS design utilizing a pre-mixed 60/40 portland cement and blast slag amendment ensured that ISS requirements of a minimum unconfined compressive strength 50 pound per square inch and permeability of 1 x 10-6 cm/sec were achieved. A sequential approach of treating the six large LNAPL plumes allowed a delineation team to determine final LNAPL treatment extents in advance of the ISS remediation team to ensure the overall schedule.
Results/Lessons Learned
This approach allowed treatment of the environmental impacts within the planned building footprint to be completed within 1.5 years of the purchase of the property. Active delineation using multiple lines of evidence (historical wells, soil sampling, temporary well points, and test pits) were utilized to delineate weathered LNAPL plumes located primarily within historic fill. Sequencing delineation allowed ISS pilot tests to be performed in each plume to optimize mix designs in varying soil, moisture, and LNAPL conditions resulting in a >96% pass rate of ISS cells. The vast debris encountered within historic fill was managed by re-incorporating it within the ISS mixture realizing significant disposal and production rate benefits. Upon completion of the aforementioned remediation activities, monitoring wells installed during the first quarter 2023 have confirmed successful remediation.