Methane Gas Production and Vapor Intrusion Potential Following Carbon-Based Substrate Injections for Enhanced Reductive Dechlorination

摘要

Background/Objectives. In an effort to promote the bioremediation of chlorinated solvents in situ, carbon-based amendments have become an increasingly common and cost effective remedial action for promoting enhanced reductive dechlorination (ERD) of chlorinated ethenes to the innocuous end product ethene. Vapor intrusion (VI) from contaminated sites into occupied buildings continues to increase as a pathway of potential concern within the Department of Defense (DoD) and the regulatory community. The high volume of methane production that can potentially result from injection of an ERD substrate into groundwater has become an increasing concern due to the potential for methane to migrate toward and potentially into buildings at levels above risk thresholds. Two separate evaluations were conducted to evaluate methane generation, migration toward existing structures, and the potential for VI; one at Marine Corps Air Station (MCAS) Cherry Point on the east coast of North Carolina and another at Grants Chlorinated Solvents Plume (GCSP) Superfund Site in Grants, New Mexico.