Aerospace Manufacturing Facility RCRA Corrective Action

(Gresham, OR)  Landau Associates has provided environmental consulting services since 1986 in response to chlorinated solvent soil and groundwater contamination at a Gresham, Oregon manufacturing facility. The facility is located above a complex multi-aquifer groundwater system, which is used seasonally by the City of Portland to supplement the municipal water supply. Groundwater contamination from an adjacent industrial facility has resulted in a co-mingled plume beneath the facility.

Landau Associates conducted a RCRA facility investigation (RFI), corrective measures study (CMS), and a Superfund-based remedial investigation/feasibility study (RI/FS) of contamination in a second, lower aquifer. This RI/FS was accomplished under state regulatory lead and was conducted jointly with the nearby facility whose operations contributed to contamination in the second aquifer. Site investigation and conceptual model development was conducted under U.S. Environmental Protection Agency (EPA) oversight with oversight subsequently transferred to the Oregon Department of Environmental Quality (DEQ). A significant aspect of this work was the integration of the RCRA- and state-based Superfund actions to satisfy the requirements of both programs. Landau Associates assisted the client in Consent Order negotiations with EPA Region 10 and with a memorandum of understanding between EPA and DEQ. We concurrently assisted our client in successful litigation against the nearby facility for cost recovery and contribution related to the comingled plume and in litigation brought by the City of Portland alleging damage to the water supply. 

Landau Associates developed a detailed conceptual model incorporating data from over 1,000 wells, flow and stage measurements from rivers and lakes, and hydraulic testing. We developed a nested regional (340 sq. miles) and local (6 sq. miles) numerical model that was adopted by state and local agencies. The calibrated model was used to develop remedial alternatives, account for different municipal water withdrawal scenarios, and design a groundwater pump-and-treat system.

Landau Associates designed and implemented various corrective measures, including a groundwater pump-and-treat system, soil vapor extraction (SVE) systems, and aquifer bioremediation.

  • The 22-well pump-and-treat system, operated since 1989 for plume containment and treatment in two aquifers, has treated over 4.4 billion gallons of groundwater with removal of approximately 4,300 pounds of contaminants.
  • SVE operations completed in two solvent source areas removed approximately 3,700 pounds of contaminants.
  • Anaerobic bioremediation has been used to treat source areas and high concentration areas of the dissolved plume in the shallow aquifer.

Large-scale dye tracer testing (120,000 gallons) was performed to design aquifer bioremediation. Bioremediation was implemented in a source area and 10 acres of the plume to 165 feet below grade by injecting 140 tons of vegetable oil in 217,000 gal of oil-water emulsion. Aquifer treatment resulting from this bioremediation effort allowed the client to forgo the cost of a vapor barrier beneath a new building, reduced pump-and-treat costs, and decreased the projected remediation timeline. This completed bioremediation effort received a 2011 Engineering Excellence Award for innovation from the American Council of Engineering Companies—Washington. SVE and anaerobic bioremediation are being applied concurrently in an additional source area within the shallow aquifer. Aerobic bioremediation is performed on a separate release of petroleum-based machine coolant to the shallow aquifer.