Enhanced Biological Degradation Groundwater Remediation Project 60 Minute Cleaners - College Parkway, Fort Myers, Lee County, Florida

Abstract

A soil and groundwater remediation system was designed and installed at the 60 Minute Cleaners in Ft. Myers Florida under the State of Florida Drycleaning Solvent Cleanup Program (DSCP) in March 2003. A contamination assessment was completed at the facility which showed chlorinated solvents concentrations, associated with drycleaning operations, exceeding soil and groundwater cleanup target levels beneath the facility with a groundwater plume migrating approximately 200 feet downgradient of the facility. A remedial system was designed and implemented which included a soil vapor extraction (SVE) system to address affected soil. To address affected groundwater, nested groundwater extraction wells were installed downgradient of the drycleaning facility and multiple injection wells installed upgradient of the facility. The primary objectives for installation and operation of the remediation system were: 1) Enhance the rate of dechlorination of dissolved chlorinated ethenes with indigenous microorganisms in the presumed source area (beneath the former drycleaning facility) by injecting ethyl lactate into the surficial aquifer. A groundwater-extraction system, with recovery wells downgradient of the source area and re-injection wells upgradient of the source area, provides accelerated movement of the ethyl lactate through the aquifer in the source area. It is expected that intrinsic natural-attenuation processes will be adequate for remediation of dissolved-phase chlorinated ethenes outside of the source area. Dissolved chlorinated ethenes in the remediation-system influent water stream are removed by carbon adsorption with two 2,000-pound granular activated carbon (GAC) vessels, and 2) Decrease the concentrations of chlorinated ethenes in the presumed source-area vadose-zone soil with an SVE remediation system. Chlorinated ethenes within the soil-vapor stream were initially removed prior to atmospheric discharge by two 170-pound GAC vessels. The SVE remediation system was turned off on September 6, 2005, and the groundwater-remediation system was turned off on October 14, 2005, to allow the Site to be monitored for natural-attenuation processes. Chlorinated-VOC concentrations have significantly decreased on both a mass and molar basis since startup. A significant decrease in dissolved tetrachloroethene (PCE) concentrations in monitoring wells was observed in the source area, while an increase in dissolved-PCE breakdown products was observed throughout the Site in monitoring wells outside of the source area, especially VC concentrations. Based on recent data, the VC concentrations have shown a decreasing trend in the monitoring wells during the third year of remediation-system operation. During the March 2006 sampling event, there was a continued decrease in the concentration of dissolved chlorinated-ethenes in groundwater. Chlorinated-ethene concentrations remained below the Florida Department of Environmental Protection's (FDEP) natural attenuation default concentrations (NADCs) in the monitoring and recovery wells sampled during March 2006 sampling events.