Marine Terminal Groundwater Control System Design and Installation
A refinery in a sensitive marine environment was impacted by LNAPL and dissolved-phase petroleum hydrocarbons. When asked to finalize the existing remedial plan, Trihydro identified data gaps, operational risks, and safety concerns, leading to further investigation and an updated conceptual site model. These efforts resulted in a redesigned remedy—a 42-well groundwater extraction system supported by tidal studies, aquifer testing, and groundwater modeling.
Investigations confirmed that part of the refinery, located in a sensitive marine setting, was affected by light non-aqueous phase liquid (LNAPL) and dissolved-phase petroleum hydrocarbons. An earlier remedial action plan recommended a 1,900-foot groundwater interceptor trench to control shallow groundwater and four recovery wells to capture deeper groundwater.
Marine Terminal engaged Trihydro to finalize the engineering design for this plan. During our review, we found significant data gaps that reduced confidence in the remedy’s effectiveness, as well as concerns that it could disrupt operations and pose health and safety risks. To address these issues, Trihydro proposed and received approval to conduct an additional field investigation and develop an updated conceptual site model reflecting LNAPL distribution and mobility.
The updated evaluation showed that the originally proposed remedy would not meet site goals. Trihydro instead developed an alternative solution: a linear series of groundwater extraction wells. We performed tidal studies and aquifer testing, then completed groundwater modeling, design, and installation of the 42-well system. This approach not only provided a more effective remedy but also saved Marine Terminal an estimated $2 million compared to the original plan.
