Motco, Inc.

Overview

The Motco, Inc. site sits in La Marque, Texas, in Galveston County. It operated first as a styrene tar recycling facility from 1959 to 1961, then as an industrial disposal facility from 1964 to 1968. Those operations left soil and groundwater contaminated with hazardous chemicals. EPA placed the site on the National Priorities List (NPL) in September 1983. The NPL is the federal government's roster of contaminated sites that need long-term cleanup attention.

EPA identified over 170 contaminants of concern across soil, groundwater, surface water, sediment, sludge, liquid waste, and free-phase nonaqueous phase liquid (NAPL). Key contaminants include volatile organic compounds such as benzene, trichloroethene, and vinyl chloride; chlorinated solvents including 1,1,1-trichloroethane and tetrachloroethane; metals such as arsenic, lead, chromium, mercury, and cadmium; polycyclic aromatic hydrocarbons like benzo[a]pyrene and naphthalene; and polychlorinated biphenyls (PCBs).

Cleanup was split into two operable units. Operable Unit 1 targeted source control, using off-site incineration of liquid wastes and on-site capping of contaminated soil. Remedial action for this unit began in December 1988. Operable Unit 2 focused on groundwater, and work included excavating contaminated soils, installing a slurry wall, extracting and treating contaminated groundwater, and removing dense non-aqueous phase liquids. Groundwater remedial action began in December 1993. Physical construction across both units finished in September 1997. Long-term groundwater response actions began in September 2000 and continue today.

EPA completed its most recent five-year review in July 2022. That review confirmed the site is protective of human health and the environment in the short term. However, it flagged a remedy performance issue: upward hydraulic gradient control between the third shallow transmissive zone and the first upper Chicot aquifer zone was not met at all six monitoring wells. This means groundwater is not moving exactly as the cleanup design intended. Continued protectiveness depends on ongoing groundwater monitoring, evaluation of monitoring well data, and management of a hydraulic connection between contaminated groundwater and two nearby supply wells. EPA has determined that human exposure at the site is currently under control and that contaminated groundwater migration is stabilized. The site reached "sitewide ready for anticipated reuse" status in August 2012 and has not yet been deleted from the NPL.

Community members can read the 2022 Five-Year Review Report online or at local repositories. In-person questions can be directed to the MOTCO Site Office at 2917 Highway 3 in La Marque, Texas, by calling (409) 935-8834.