AEM was contracted to complete a Corrective Action Plan (CAP) - Parts A&B, along with any necessary remediation at a former convenience store site in Talbotton, Georgia, where Phase I and II Environmental Audits detected releases of gasoline to soil and groundwater.

AEM completely delineated the extent of contamination, completing numerous soil borings, installing over 20 groundwater monitoring wells (including a deep monitoring well drilled into bedrock over 135 feet below ground surface), and monitoring numerous wells installed by Geoprobe®. The results of the soil and groundwater assessment indicated large amounts of free-phase gasoline were present in the former tank pit area, and dissolved benzene, toluene, ethylbenzene and xylenes (BTEX) were present in groundwater both on-site and off-site in relatively large concentrations.

AEM evaluated a number of technologies for the remediation of contaminated soil and groundwater and proposed Dual-Phase Vacuum Extraction (DVE) for removal of the free product, remediation of contaminated soil, and remediation of the dissolved BTEX in the downgradient plume of contaminated groundwater. AEM conducted a three-day pilot study of the DVE technology.

The results of the pilot study were submitted to the Georgia Environmental Protection Division (EPD) as part of the Corrective Action Plan (CAP) Part B Report, and included a design of a full-scale system to remediate the site. The CAP B presented modeling results that demonstrated dissolved BTEX outside of the source area would biodegrade before impacting any downgradient receptors, including a municipal well.

After approval of the DVE system by EPD, AEM procured and constructed the full-scale remediation system in early 1999. After 6 months of continuous operation, free product thicknesses measured in monitoring wells onsite had been reduced to near non-detectable levels. Concentrations of dissolved BTEX in groundwater in on-site groundwater monitoring wells had been reduced by approximately two orders of magnitude, from nearly 10,000 parts per billion (ppb) to just under 200 ppb. In addition, groundwater monitoring wells offsite, including one nearly 100 feet in the downgradient direction, showed reduced concentrations of BTEX by almost 80%, as compared to measurements before the start-up of DVE system operations. Due to the effectiveness of the treatment system on the off-site monitoring wells, AEM avoided the construction costs of expanding the system off-site.

AEM continues to monitor the DVE system's operation, and monitors the natural attenuation of BTEX compounds in the downgradient plume of contaminated groundwater.