State Highway 123 PCE Plume
The site is near the intersection of State Highway 123 and Interstate Highway 35 in San Marcos, Hays County. A plume of contaminated groundwater originates in the area of west State Highway 123 near Ebony Street. Groundwater flows generally north to northeast and emerges through a seep near Willow Springs Creek.
The plume was first discovered in 1986 during investigations related to removing an underground petroleum storage tank in the vicinity.
Superfund Registry and Investigation
The TCEQ proposed the site to the state Superfund registry in 2001 and conducted a remedial investigation from 2001-2004. The investigation identified tetrachloroethene (PCE) and PCE-related chemicals at levels exceeding the protective concentration limits.
In 2005, the TCEQ issued an administrative order listing the site on the state Superfund registry. The remedial action involved establishing a plume management zone, monitoring for natural attenuation, and institutional controls on affected properties to prevent future exposure to the chemicals of concern.
The site is currently in the operations and maintenance phase of the Superfund program. The TCEQ continues to routinely monitor the groundwater within the plume management zone and at the seep to make sure the selected remedy remains effective.