Leveraging Sequence Stratigraphy to Accelerate Site Remediation: Pliocene Citronelle Formation, Eglin Air Force Base, Florida, USA

At Eglin Air Force Base (AFB) in the Florida Panhandle, a groundwater extraction and treatment system was installed to contain and remediate a chlorinated solvent plume. After 2 years of operation, the system was not removing the contaminant mass at the rate predicted or required to meet performance-based contract terms. As a result, a sequence-stratigraphic analysis was initiated to develop a strategy to improve performance. Sequence Stratigraphy methods were employed to identify a marine flooding surface (mfs) formed during a relative sea level highstand. The analysis also found that the mfs was locally eroded away, indicating that incised valleys were eroded into the formation during a relative lowstand of sea level. These valleys were backfilled with coarse-grained fluvial and estuarine strata. The analysis concluded that the groundwater extraction system lacked an extraction well screened within the coarse-grained valley fill. An additional extraction well was installed, which targeted the incised valley fill and resulted in a significant increase in contaminant mass removal rate without increasing system capacity or operational costs. This case study suggests that efficiency improvements are tenable at many sites where groundwater remediation is occurring within the Surficial Aquifer System of the Gulf Coast (Citronelle Formation) as well as sites in similar geologic settings worldwide.