ABSTRACT

The disposal of chlorinated hydrocarbons in an unlined pit prior to RCRA regulations contaminated the shallow ground water at the Exxon Chemicals Baton Rouge Polyolefins Plant. This impact was discovered through a due diligence survey. Through successive investigations the upper three water-bearing units were found to be impacted by multiple contaminants which formed both a dissolved and a DNAPL plume.

Soil vapor extraction and air sparging in the uppermost zone and pump and treat for contaminated water removal in all three zones was proposed and implemented after Agency approval. During the past 4+ years of operation, the system effectiveness has been monitored and adjustments made to enhance contaminant recovery.

With the recent promulgation of LDEQ RECAP Regulations, final cleanup levels based on site specific parameters and exposure risk evaluations have set an achievable endpoint to this remediation effort. The primary concern in this project has been the control of downward migration of contaminants and restoration of the shallow aquifers. Now the focus is on exposure pathways and receptors that may be exposed to the reduced levels of contaminants. In this evaluation, if no exposure occurs or the levels are below those that present health risks to any receptors, then the remediation has been effective and may be terminated. This paper will focus on the team approach to managing the problems of downward movement of DNAPLs, improving contaminant recovery, determining exposure pathways, evaluating risk to receptors and developing and implementing timely and reasonable environmental solutions.

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