W&M obtains MSD and VCP Closure for Laboratory Property
W&M obtained a Certificate of Completion through the Texas Commission on Environmental Quality (TCEQ) Voluntary Cleanup Program (VCP) at a groundwater contamination site which required risk-based assessment of soil, groundwater, surface water, sediment, and soil vapor; chemical and biological groundwater remediation; and a restriction on potable groundwater use through a Municipal Setting Designation (MSD).
The Client leased/operated an analytical laboratory within a portion of the property. Chlorinated laboratory chemicals were used and released to the subsurface via leaking building utility lines. Investigatory activities indicated chlorinated solvents had contaminated underlying groundwater units such that federal maximum contaminant levels (MCLs) were exceeded. The Site is bordered on two sides by drainage bayous, which required assessment of potential ecological exposures in sediment and surface waters.
Through risk-based environmental assessment activities, W&M identified and classified multiple groundwater bearing units at the Site as Class 3 (not suitable for drinking) groundwater resources and eliminated potential vapor intrusion concerns by direct assessment of soil vapor concentrations. Through significant ecological evaluation, the groundwater-to-surface water and sediment exposure pathways were eliminated from further assessment/remediation. However, concentrations of volatile chemicals in groundwater still exceeded risk-based criteria.
W&M developed a 2-part strategy to both modify the risk-based cleanup criteria and decrease chemical concentrations in groundwater to meet it. The MSD eliminated the groundwater ingestion pathway and groundwater treatment via subsurface injections was used to decrease chemical concentrations through in situ chemical oxidation (ISCO) and biological reductive dechlorination.
The City of Webster does not have an MSD ordinance and, therefore, had never adopted one for any property located within the municipality. As a result, W&M worked with Site property owners, owners of all public water supply wells located within 5 miles of the Site, and the cities of Webster, Houston, League City, Friendswood, Nassau Bay, Clear Lake, municipal utility districts (MUDs), and water control improvement districts (WCID) to obtain all required resolutions in support of the MSD. The MSD was certified by the State of Texas in February 2018 which, along with reduced groundwater chemical concentrations, closed the groundwater ingestion exposure pathway and made the Site eligible for regulatory closure. The VCP Certificate of Completion was issued by TCEQ in January 2019.