Chemical Oxidation via PulseOx – Convenience Store

The challenge:

A hydrogeological investigation of a UST release revealed an 800’ dissolved phase MTBE, TBA and benzene plume that traveled beneath several properties and impacted residential water supply wells. Objectives were to remediate the plume below Tier 1 screening levels in less than one year, keep project costs below insurance coverage, and avoid community disruption.

The GES solution:

Following site characterization and remedial pilot testing, GES prepared a life cycle cost analysis that included modeling alternative approaches to evaluate potential results and durations. Chemical oxidation using PulseOx was deemed the most cost-effective, most rapid, and least disruptive approach.

The benefits:

After three months of remediation, only three of the 45 sampling locations (all on-site) indicated detectable concentrations of BTEX. Prior to remediation, there was little to no dissolved oxygen throughout the plume, and after three months there were zones as high as 25 ppm.

After five months of remediation, BTEX was not detected in any of the sampling locations. Only one well indicated MTBE concentrations greater than 60 µg/L, and only one well indicated TBA concentrations greater than 50 µg/L.

After seven months of system operation, DNREC granted approval to deactivate the remediation systems and initiate one year of groundwater monitoring for closure.

After one quarter of post-remediation monitoring, BTEX was not detected in any of the 11 sampling locations. Only one well showed MTBE concentrations above 30 µg/L, and all wells indicated TBA concentrations of less than 50 µg/L.

After three quarters of post-remediation monitoring, only one well, located in the original source area, indicated MTBE concentrations above 30 µg/L. Concentrations of BTEX, MTBE, and TBA were not detected or were less than 4 µg/L in the other eight compliance sampling locations. No Further Action designation was achieved.