Client: Real Estate Developer
Project: Remedial System Design, Installation & Operation
Location: New Jersey
Description: A discharge was discovered at a property when a former owner was closing a 15,000-gallon fuel oil underground storage tank (UST). At the time, some contaminated soil was removed and post-excavation soil samples were collected. When sample results came back with elevated levels of total petroleum hydrocarbons (TPHC), additional soil and ground water sampling was conducted in order to assess the extent of contamination.
EWMA became involved with this case when our client purchased the property and asked us to perform additional remedial investigation work to complete contaminant delineation activities and develop a Remedial Action Workplan to address the remaining contamination. During the soil investigation, EWMA discovered that the horizontal extent of contamination was basically limited to the area of the former UST. However, results of vertical delineation work indicated that impacted soil remained in the capillary fringe, corresponding to a depth of about 21 to 28 feet below grade. For ground water contamination, it was determined that separate-phase product existed on the water table below the former UST area.
Prior to deciding upon the chosen remedial action, EWMA conducted a remedial alternatives analysis to determine the best course of action for removal of the separate-phase product. Based upon the results of pilot studies, it was determined that to remediate both the residual TPHC in capillary fringe soil and separate-phase product in ground water, a total fluids recovery system, combined with in-situ soil bioventing, would need to be installed. The total fluids recovery system was designed to convey product and ground water to a mobile treatment unit where the product was separated. The soil bioventing process provided oxygen to the affected area to stimulate microbial degradation. When necessary, enhanced fluid recovery (EFR) was used to assist in the removal of separate-phase product from the water table.
EWMA provided a guaranteed fixed-price contract to remediate the property. Throughout the entire process more than 335,000 gallons of ground water was recovered and treated (of which 772 gallons was product) via the on-site treatment system, and over 3,000 gallons of product and ground water were recovered via EFR. After two and one-half years of system operation, laboratory analytical results demonstrated that the active ground water treatment and soil bioventing process achieved compliance with respect to both the NJDEP Ground Water Quality Standards and the Soil Cleanup Criteria. Equally important to the client was the fact the project was completed below the guaranteed fixed-price and within the projected project time frame.