Grant County Ephrata Landfill 1

Ecology and the two parties responsible for cleanup, Grant County and the City of Ephrata, have negotiated an agreed order for cleanup work at the Grant County Ephrata Landfill 1. The order includes an interim remedial action plan outlining cleanup that will be completed before the remedial investigation/feasibility study to guide final cleanup.

The City of Ephrata began operating the Ephrata Landfill around 1942, managed it until 1974, and owned it until 1994. Grant County has managed the landfill since 1974, and owned the landfill since 1994. The landfill was an open dump before 1962. Waste was put into an unlined cell until a new, lined cell with leak containment opened in 2005; this new landfill still accepts waste.

About 2,000 drums of industrial waste were buried in August 1975. The Environmental Protection Agency added the landfill to the list of potential hazardous sites in 1979. Ecology completed a Phase I site investigation in 1987, and groundwater sampling began in 1988. In 1990, contaminants, including metals, solvents, and other chemicals, were found in groundwater.

Since 2007, the site has had ongoing investigation into the extent of contamination, and the parties responsible have completed a number of interim cleanup actions.

2008: Drum removal

All 2,353 drums of industrial waste were removed from the north end of the landfill. Contaminated soil and spilled drum contents that were hazardous waste were sent to a disposal facility. Photos of the drum removal are available on Ecology's Flickr account.

2009: Landfill capping

A protective cap was completed over the old unlined cell, including the area where the drums of industrial waste used to be buried. This cap keeps rain and snow melt from infiltrating through contaminated soil.

2012: Soil removed from north end

Contaminated soil from the Neva Lake Road extension was removed in November and December 2012.

2017: Pilot system installed to remove soil contamination

The multi-phase extraction (MPE) pilot test started on May 23, 2017, and continued for 4.5 months. The purpose of the test was to evaluate the ability of MPE to treat contaminants in the uppermost groundwater and soil. Work included installing new extraction and observation wells, piping, contaminated vapor and liquid treatment systems, and an evaporation pond. A total of 87,000 gallons of groundwater were extracted, treated, and disposed. A total of 7,100,000 cubic feet of vapor were extracted, treated, and vented. The pilot test showed that MPE was successful in treating groundwater in the uppermost groundwater zone, but that changes would need to be made on a full-scale system.

2018–2019: More soil removed from north end and investigation work continues

In February 2018, 25 test pits were sampled in the area where contaminated soil was removed in 2012. The sampling found an area of arsenic-contaminated soil. The area was excavated to bedrock, and about 1,210 cubic yards of contaminated soil were removed. The PLPs proposed additional investigation in 2018, and 81 new groundwater monitoring wells were installed in 2019.

2024: Expanded pilot system

Grant County signed an amendment to the order with Ecology to expand the MPE system into the deeper groundwater zones and across a wider area of the site. The parties responsible for cleanup proposed this as the final cleanup action. We did not believe there was sufficient data to choose this action as the final remedy, so it is being implemented as an interim action.

The expanded MPE system will be completed in 2026. In the meantime, the smaller scale MPE system is running seasonally to treat contaminants in groundwater. Ecology will use groundwater and system data to decide whether the MPE system is an effective remedy for the groundwater plume.