Emergency Response Actions, Remedial Investigation, Remedial Design, and Corrective Action at a LUST Site in Decatur, Alabama
PM Environmental, Inc. was retained to provide initial abatement and emergency response actions at the Food Mart convenience store that utilizes USTs for storage of motor fuels for retail sale. The site is located directly across from Decatur General Hospital. Maintenance employees at the hospital noted a sheen and petroleum odors emanating from a sump located in the basement of the hospital. The hospital notified the Alabama Department of Environmental Management (ADEM), who directed the client to immediately begin abatement and site stabilization activities due to potential dangers associated with the suspected release.
PM met with representatives of ADEM and Decatur General Hospital and formulated an appropriate course of action. Initial efforts focused on determining if explosive or other hazardous environments existed at the hospital. The sump, manholes, sewer inlets and other structures were monitored. PM began an aggressive site assessment including installation of soil borings and groundwater monitoring wells. Data suggested that a substantial release had occurred at the site and had migrated toward the hospital.
PM conducted all phases of site characterization and performed several mobile enhanced multi-phase extraction events to remove free phase hydrocarbons from monitoring wells and exert hydraulic control to minimize further plume migration to the hospital and sump. Approximately 28 groundwater monitoring wells are associated with this site. Pilot testing and dual phase extraction remediation technology was performed and the technology was deemed appropriate and cost effective at the site. The Corrective Action Plan (CAP) and project costs were reviewed and approved by ADEM.
PM supervised the installation of 16 recovery wells, a complicated trenching and piping system, and placement of 40 horsepower dual phase extraction and treatment system with a liquid ring pump. The recovery wells were placed on both sides of the street and connected via a horizontal boring advanced underneath the road to alleviate the need to shut down the primary access road for emergency vehicles to the hospital.
PM conducts monthly operations and maintenance, quarterly groundwater monitoring of the impact, and other troubleshooting activities of the system on an as needed basis. After the initial troubleshooting in the first quarter of operations, the system has an up time average of over 93%, with an average pumping rate of 3.3 gallons per minute. The Remediation System has significantly reduced the amount of free product measured in the monitoring wells. No additional petroleum odors or sheen have been recorded in the hospital sump.