Site Investigation and Bioremediation of Active Manufacturing Facility

(Auburn, WA)  Landau Associates has provided environmental consulting services at an active manufacturing facility in Auburn, Washington since 1990. Our services have included performance of a site-wide remedial investigation (RI) and interim remedial actions supporting the sale of surplus properties. Landau Associates provided concurrent environmental remediation and stormwater compliance services during demolition of eight large warehouse buildings on a 50-acre parcel that was sold and redeveloped as a regional grocery distribution facility. We designed and implemented in situ bioremediation on a second surplus parcel (42 acres) that included a manufacturing building and former vapor degreaser that was a primary source of trichloroethene (TCE) groundwater contamination extending to 40 ft below grade. Nearby portions of the shallow alluvial aquifer are used by the City of Pacific as a source of municipal water supply. Work was performed under an Agreed Order between the client and the Washington State Department of Ecology (Ecology).

Landau Associates completed expedited investigation and remediation to facilitate sale of the 42-acre parcel containing the TCE source area. Site investigation planning and activities, culminating in delineation of the source area and the 8.5-acre onsite plume, were completed in four months. Based on our feasibility evaluation of viable remedial alternatives, we recommended an aggressive enhanced in situ bioremediation interim action to achieve the client’s requirement for a rapid cleanup before sale of the property.

Landau Associates injected approximately 400,000 gallons of donor solution (groundwater with sodium lactate and vegetable oil) during three injection events over 15 months. We performed aquifer tracer testing to evaluate hydrogeologic parameters in support of design. The injections stimulated reductive dechlorination of TCE over a treatment area of approximately 0.7 acre, with TCE and breakdown product concentrations reduced to below maximum contaminant levels (MCLs) for drinking water. Groundwater monitoring, required for the last five years following sale of the property, demonstrated no rebound in contaminant concentrations. The expedited cleanup of this site, including work plan preparation and Washington State Department of Ecology approval, site investigation, feasibility evaluation, and interim action implementation, was completed in just over 1.5 years. The results of the cleanup satisfied the requirements of both the seller and buyer and sale of the parcel was completed as scheduled.

Currently, Landau Associates is conducting an ongoing vapor intrusion assessment related to the manufacturing facility, which is located in a river valley where the hydrologic environment varies greatly. Several dozen sub-slab soil gas samples and indoor air samples have been collected from industrial, commercial, and residential buildings. The sample data is used to inform risk management decisions for the project.