Southern Flow Corridor Project - Old Mill Site Remediation, Tillamook, Oregon

Phase I and II ESA, Remedial Investigation, Remediation Management
2017 Phoenix Award Winner – USEPA Region 10


Anderson Geological, Inc. (AGI) completed the environmental site characterization, assessment, remediation design and remediation management for the Old Mill site in Tillamook, Oregon. The site was part of the 500-acre flood control project that involved removal and reconstruction of flood control features within farm land and sensitive ecological habitat.


Extensive soil sampling by AGI on the ten-acre former log-peeling mill site identified locations where soil contaminants in the proposed excavation areas exceeded ecological screening levels. The work involved the removal significant volumes of contaminated soil and fill material from most of the site, which would allow unrestricted flow of flood waters through the area.


Remediation of the site involved the removal of 12,600 cubic yards of contaminated soil, concrete, asbestos-containing construction debris and other fill material from the site, which included a former dump site. An additional 15,000 cubic yards of non-contaminated soil was removed or re-located on the site, reducing the elevation of the Old Mill site by up to 7 feet. Areas where the remaining soils exceeded ecological screening levels were capped with topsoil and elevated, linear tree berms to minimize exposure to ecological receptors.


In lieu of landfill disposal, approximately 11,500 cubic yards of the contaminated material was placed in an engineered containment cell on the Old Mill site. Use of the containment cell avoided the need for approximately 575 trips to the landfill with truck and trailer. The remaining 1,100 cubic yards of material, which included asbestos-containing debris, was landfilled off-site.


The cell, which included a passive methane venting system and a cap of two feet of clean topsoil, was finished with a parking lot for visitors to the area. A hiking trail is planned that will cross the Old Mill site, connecting the area to the Hoquarten Interpretative Trail.


The Southern Flow Corridor project, including the Old Mill site, was selected as the 2017 Phoenix Award Winner for brownfield re-development from the US EPA Region 10.