Pipe-coating businesses, run by the Hall Process Company and Northwest Pipe and Casing Company, operated on the southern part of the 53 acre site from 1956 to 1985. During the pipe-coating operations, volatile organic compounds (VOCs), polynuclear aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were released at the Site into the soil and groundwater. The site was eventually listed on the National Priorities List (NPL) on October 1992, and remedial activities were performed between August 2001 and September 2004. However, during the site Five Year Review in 2006, a groundwater remedy emplaced during the Remedial Action was found to not be functioning properly. After further site characterization, DNAPL was found to be in one of the site groundwater monitoring wells, and coal tar bodies were also discovered in subsurface soils.
Due to the discovery of coal tar bodies and DNAPL, the EPA Region 10 Remedial Program requested assistance from the EPA Removal Program in order to remove the source of soil contamination so that a new groundwater remedy could be implemented. Further contaminated soil removal was deemed necessary before the Remedial Action groundwater remedy could be effective.
The removal Action Memo was signed on July 28, 2009 and removal site activities began on August 12, 2009. However, site work was halted in November 2009 due to an unexpected increase in costs as well as delays from the onset of significant precipitation towards the end of the removal schedule. Increases in costs were due to several issues: 1) an unexpected increase in the volume of dense non-aqueous phase liquid (DNAPL) impacted soil at the site, 2) the need for an increase in subsurface soil amendments, 3) a change from freeze shoring applications to standard metal frame shoring, and 4) an increase in rainfall and concommitant increase in saturation levels of site soils and weight of excavated material. This additional weight significantly increased transportation and disposal costs. In order to better manage these costs, site work was halted until June 2010.
Work conducted through the fall of 2009 is described in detail in individual POLREPS on this website. For further site history, please previous site POLREPS.
This POLREP covers site activities beginning on June 1, 2010 through June 15, 2010.
On June 1, 2010 EPA, ERRS, and START mobilized to the site and set up equipment and command posts in order to resume work. Planned worked consisted of trucking contaminated stockpiled soil off-site for disposal in a municipal RCRA Subtitle D landfill.
On June 2 through June 14, 2010 loading and trucking of stockpiled soil to the landfill began on June 2. ERRS transfered contaminated soils from the stockpile to contracted dump truck haulers using an excavator. START monitored potential emissions from transfer work, including air monitoring for volatile organic compounds, carbon monoxide, hydrogen sulfide, explosive vapors, breathable oxygen, and total particulates.
A total of 230 loads of contaminated soil (6,933.7 tons) was transported to the lWASCO landfill near The Dalles, Oregon between June 2 through June 11.
On June 9, 2010 ERRS begins to pump and remove ponded water near the northeastern border with Oregon Iron Works. Ponded water was associated with potentially raising the water table in the middle of the site and altering the natural hydraulic gradients.
On June 11, 2010, silt fencing was erected around areas where additional soil capping will occur. Additional low permeability soil capping is required in order to deter infiltrating groundwater that may be affecting hydraulic gradient movements per the Action Memorandum Addendum signed May 27, 2010.
START is planning to collect confirmation soil samples on June 16, 2010 to determine if any cross-contamination from the stockpile to surficial soils occurred even though a liner membrane was emplaced below the stockpile.
There are no further removal actions planned for this site.
1. Complete loading, hauling and disposal of stockpiled soil to landfill.
2. Determine if cross-contamination from the stockpile to surface soils underneath the stockpile footprint has occurred.
3. Apply additional low permeability geotextile and soil cap on an area about 125 by 80 square feet over Excavation Area #1 to deter infiltrating groundwater and allow natural groundwater gradient movements.
4. Demob from the site.
Additional water weight added to the soil stockpile due to heavy precipitation during fall 2009 and spring 2010 has resulted in significant increased transportation and disposal costs.
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