Client: Real Estate Developer
Project: Remediation via Soil Vapor Extraction/Air Sparging
Location: New Jersey
Description: Remediation of soil and ground water contamination was required when a previous consultant discovered a discharge from a gasoline underground storage tank (UST) system. The property is situated in an area of mixed commercial and residential use, and was originally owned by a milk distributor. In 1985, the property was purchased by EWMA’s client who developed it into a 3-story commercial office building. During a Phase I assessment of the property, a consultant identified a former UST and dispenser system. Additional investigation work was completed and constituents of gasoline were identified in the soil and ground water.
EWMA was originally retained to delineate the extent of soil and ground water contamination at the property. Sampling was performed at the property and xylene-impacted soil and ground water was found to exist under a covered parking area in the northeast quadrant of the property. Based on the findings of the sampling activities, EWMA concluded that excavation of the source area soil was an infeasible remedial alternative because of the low ceiling and concrete footing in the parking area. Instead, EWMA developed a remedial approach that would take into consideration the contaminants that were present and the impeding conditions at the site.
Based upon the final results of soil and ground water delineation/investigation activities, EWMA designed a remediation system that combined soil vapor extraction (SVE) with ground water air sparging (AS). EWMA believed that the use of both technologies could be used cost-effectively to treat both media in the affected area. To determine whether the use of SVE/AS would be an effective remedial option, EWMA conducted a pilot study that utilized a pilot version of the propsed treatment system, and the results were favorable. In response, EWMA applied for and received approval from the NJDEP for installation the of the SVE/AS remediation system.
EWMA provided the client with a guaranteed cost to clean up the property for $300,000. Once the client agreed to the scope of work, EWMA began system installation in early 1997. Start-up of the system occurred in July of 1997. Influent vapor concentrations decreased significantly over the first six months of system operation, indicating a decreased contaminant mass in the subsurface. Additionally, laboratory analysis of ground water samples confirmed a significant reduction in contaminant concentrations. Based upon the favorable results of the system operation during the first six months, EWMA proposed an accelerated schedule for the remedial system. After one year of operation, the NJDEP approved of system shutdown, as several rounds of soil and ground water sampling indicated that contaminants were below NJDEP action levels. The client was issued a No Further Action (NFA) letter from the NJDEP in 2000, and was able to complete the remediation within six months after the NFA letter was received.
