Human Health Risk Assessment and Regulatory Closure at a Site in Irving, Texas

Client

Confidential

Services Provided

Subsurface Investigation; Groundwater Monitoring; Risk Assessment; Feasibility Study and Pilot Testing; Remediation System Design; Regulatory Liaison

Three workers operate a large drilling rig beside a fenced concrete area in an empty parking lot, with equipment and barrels nearby. A beige building and stacked crates are in the background.

Location

Irving, Texas, USA

Project Practice Areas

Contaminated Sites, Building Health

Type of Facility

Closed Industrial Site

Project Specifics

Chlorinated solvents in soil and groundwater beneath this former manufacturing facility are believed to have originated from a former waste solvent underground storage tank. Soils at the affected property consist of plastic clays overlying approximately 150 feet of competent shale. Limited contaminant migration has occurred through fractures in the clay soils. The client (property tenant) expedited site closure to eliminate financial obligation to property owner.

Geosyntec Scope of Services

Geosyntec was retained to delineate the nature and extent of contamination in groundwater and identify regulatory closure options for the Site. Because of time-related financial penalties negotiated between the Client and the site owner, Geosyntec conducted this work on a fast-track schedule. Remedial investigations, including the installation of 22 monitoring wells, two deep shale borings, and a comprehensive groundwater monitoring round, were completed within six weeks of contract award. Geosyntec prepared an Affected Property Assessment Report (APAR) for the Site, and pilot tested multi-phase extraction for addressing contaminants in the source area.

In conjunction with the APAR preparation, Geosyntec conducted EVS modeling and a site-specific risk assessment which demonstrated that impacted soils at the property do not pose a significant risk to human health or the environment. Geosyntec also demonstrated that impacted groundwater at the Site meets the requirements for Class 3 (low aquifer yield), and that the extent of impacted groundwater is stable.

Notable Accomplishments

After performing a detailed risk assessment to demonstrate that current site conditions do not exceed regulatory risk thresholds, Geosyntec assisted the client in pursuing a Municipal Setting Designation (MSD) for the property. This was among the first MSD applications to be filed in Texas, and it eliminated the need for remediation and drastically shortened the time required to reach regulatory closure. An affidavit of certificate of completion was issued by the Texas Commission on Environmental Quality in August 2006.

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