The following post is provided by our guest author, Graham Crockford from TRC Environmental Corporation.
Trichloroethene (TCE) has been produced commercially since the 1920s and was commonly used by manufacturing companies as a metal degreaser. TCE was historically considered environmentally harmless. Because of TCE’s widespread use prior to the enactment of environmental regulations, it is a fairly common contaminant at former manufacturing facilities, and often a risk driver for remediation. Many manufacturing companies in the automotive sector have facilities with legacy environmental liabilities related to past use of TCE for metal parts degreasing.
On September 28, 2011 the USEPA issued a long-awaited final health assessment for TCE. Since then, updated toxicity values were published in the Integrated Risk Information System (IRIS) database for use in risk assessment. The toxicity values for TCE will result in lower (more conservative) screening levels for vapor intrusion assessment, and States are evaluating how to incorporate the toxicity data into state-specific screening levels and cleanup criteria. Indoor air screening levels presented by USEPA for TCE are near the limits of detection. Use of these screening levels is complicated by the incidental use of chemicals containing TCE and other solvents used in the manufacturing process, which often result in background TCE concentrations at or near these standards. Consequently, going forward it will be very challenging to demonstrate compliance with indoor air criteria at manufacturing facilities that have affected soil or groundwater underlying the structures, when TCE is still used, even in small amounts.
Implications in Michigan
In a recent development favorable to the manufacturing sector, Michigan Governor Rick Snyder signed Senate Bill 1328 which amends several parts of the Michigan’s Natural Resource Environmental Protection Act (NREPA). SB 1328 aligns MiOSHA standards and compliance with indoor-air criteria under Part 201 for the manufacturing sector. Under SB 1328, a person can demonstrate compliance with indoor air inhalation criteria for a hazardous substance (i.e., TCE) if:
As a result, manufacturing facilities that have contaminants (including TCE) in soil and groundwater underneath their structures will no longer be held to two different compliance standards for remediation (which requires compliance with the more restrictive MDEQ vapor intrusion criteria) versus MiOSHA requirements.