T18-3708 HydrochemSJ

Project Summary MNA Under VCP Plume Management Zone
Location La Porte, TX
Service Remediation
Outcome Stable Plume, Monitoring Under Way

Targus was retained to conduct certain professional services in pursuit of a Texas Commission on Environmental Quality (TCEQ) VCP Certificate relating to groundwater for an industrial facility in the Texas Gulf Coast area. The facility (responsible party) was the leading provider of specialty maintenance services and technology solutions to the petrochemical, oil refining, and other energy-end markets. Site operations commenced in 1978 and included storage, maintenance, and servicing of industrial filed vehicles used in hydroblastic and vacuum services by various businesses for similar clientele.

Site investigation began at the VCP site in the 1990s as part of a property transaction that identified site impacts associated with the use of chlorinated and non-chlorinated solvents, acids, bases, surfactants, and hydrocarbons. Additionally, it was discovered that a nearby facility had a release of chlorinated solvents and was granted a separate VCP identifier that attributed to a co-mingled plume. Over the ensuing decades, scores of wells of uncertain configuration and integrity were installed by multiple consultants.

In order to address current conditions, Targus prepared a VCP Response Action Plan (RAP) for the subject property and co-mingled site to demonstrate the means by which natural attenuation would achieve plume stability under a PMZ. In order to accurately and more fully define the degree and extent of contamination in each of the three underlying water bearing units on both VCP sites and off-site, Targus engaged a complete survey of the 80 wells and conducted a comprehensive sampling event to verify or adjust the previously-established attenuation action levels (AALs). The results will be presented in the form of revised AAL criteria and thresholds which correctly define the extent of the protective concentration limit (PCL) exceedance zone. Arrangements are being concurrently undertaken to acquire adjoining off-site property and establish activity and use limitations (AULs) that restrict groundwater use within the footprint of the on-site and co-mingled plumes.

Thereafter, approval will be sought from TCEQ for removal of both non-critical wells and those of questionable integrity. The remainder of wells will be entered into a semi-annual or annual monitoring program intended to confirm demonstration of plume stability.