Upland Remedial Investigation, Risk Assessment, and Source Control Evaluation

MFA has provided environmental compliance, site investigation, and remediation services for this operating silicon wafer manufacturing facility since 2000. This site is characterized by multiple complex challenges, including:

• Multiple legacy impacts, including use of the site for disposal of manufactured gas plant (MGP) waste from the adjacent former Portland Gas & Coke Company, filling of the site using MGP waste and byproducts and dredge spoils from the adjacent Willamette River, historical fuel storage and release(s), and off-site migration of contaminated groundwater plumes from the adjacent former Rhone-Poulenc pesticide manufacturing facility
• Location within the Portland Harbor Superfund site
• Upland and in-water impacts
• Comingled groundwater plumes from multiple sources, and mobile dense nonaqueous-phase liquids from MGP operations in multiple water-bearing zones
• Multiple potentially responsible parties (PRPs)

The client’s challenges are varied, complex, and multi-tiered.

MFA is supporting the client in completing a scope of work under a consent order with DEQ to perform a remedial investigation, a human health and ecological risk assessment, source control evaluations for multiple pathways to the Willamette River, and a feasibility study. MFA supported the client in negotiations with DEQ to transition out of a unilateral order and enter into a consent order. MFA worked with DEQ and the client to develop a clear scope of work that differentiated the client’s responsibilities from other PRPs. MFA serves as a technical contact for the client’s interactions with the DEQ.

MFA conducted remedial investigation activities that included advancement 21 test pits and boring, installation of 20 wells within three water-bearing zones, and analysis of over 280 soil and groundwater samples up to depths of 152 feet below ground surface. Using this data, MFA was able to define nature and extent of contamination and develop a conceptual site model that identified potentially complete pathways and contaminants of potential concern for the multiple water-bearing zones beneath the Property.

With MFA’s support, the client:

• Was able to close out of a restrictive unilateral order to a more collaborative consent order with DEQ,
• Has a thorough understanding of the environmental liabilities, risks, and remedy drivers at its Site.
• Has comprehensive data to support the development of a feasibility study that will identify a protective remedy at the site.