Supplemental Investigation and Tracer Testing for Remedial Optimization and Design(PPT)

摘要

Results of a RCRA Facility Investigation (RFI), completed in April 2004 identified groundwater contamination in the surficial, intermediate, and Floridan aquifers at a former industrial landfill in central Florida. The lateral extent of groundwater contamination encompassed approximately 5 acres with a maximum depth of approximately 250 feet below land surface was delineated during the RFI. Groundwater remediation has progressed in a phased approach. Landfill materials and debris were excavated and removed from site. Following removal of the landfill materials, remedial actions focused on treatment of the impacted groundwater, including: identification and excavation of a DNAPL source area in May 2005; installation of a groundwater extraction system and an in-situ air sparge (ISAS) system placed into operation in February 2006; and expansion of the existing ISAS system and surficial aquifer groundwater recovery well network in 2009. Groundwater remediation activities conducted to date have reduced the overall lateral plume footprint to approximately 2.0 acres in size. A localized “hot spot” remains onsite in an area inaccessible to historical excavation activities. However, contaminant concentrations in the deeper aquifers have not decreased as quickly as anticipated. In 2010 a supplemental investigation using dye tracer testing was performed at the site. The purpose of the supplemental investigation was to update the conceptual site model and evaluate hyrdogeologic conditions following source area excavation and 5 years of groundwater extraction. The results of the investigation will be used to evaluate additional technologies used in a treatment train approach which could expedite site restoration, specifically whether system modification would reduce the remnant impacted groundwater plume extent and magnitude to levels acceptable for risk-based closure.