33 Highway 20, Tonasket, WA 98855


The Tonasket School District site operates as the Tonasket primary and secondary school campus. In May 1995, four underground storage tanks (USTs) were removed.


Results of analyses collected during UST removal indicated that three of the USTs had leaked.  Additional excavation was performed in an attempt to remediate impacted soil at all three release sites.  Excavation was stopped when it became apparent that the integrity of nearby building structures was threatened if excavation continued.  

Both impacted areas present a low threat to human health and the environment given the non-volatile nature of the contaminants, depth of the contaminants, and depth to groundwater in the vicinity. It was determined that both impacted areas would be managed in-place with the use of institutional controls. A restrictive covenant was recorded for the Site.  


Based upon cleanup activities and the recording of the restrictive covenant, Ecology has determined the site is no longer a threat to human health and the environment.  A No Further Action determination was issued in 1999.

You can find site documents by using the "View Electronic Documents" link in the bar on the right, or requesting information from the Central Regional Office public records coordinator.


Periodic reviews are conducted every 5 years by Ecology for sites that have Environmental Covenants and/or Institutional Controls. The review is intended to examine the effectiveness of cleanup activities and to assure the continued protection of human health and the environment.

Periodic Review Results

Based upon site visits, no repair, maintenance or contingency actions have been required.  The Tonasket School District continues to occupy the Site.  Asphalt, building structures, landscaping and play fields continue to serve as a surface cover to prevent exposure by ingestion or direct contact to contaminated soils.  Use of the Site as a primary and secondary school facility is not likely to expose contaminated soils, and is a compatible land use as long as the surface cover is maintained.  

As a result of changes to MTCA Method A cleanup levels for TPH-D and TPH-O in 2001, several of the confirmation samples collected from the Site are no longer above MTCA Method A cleanup levels.  
Soils with TPH-D and TPH-O concentrations higher than MTCA Method A cleanup levels are still present at the Site.  However, the surface covers and land use prevents human exposure to this contamination by ingestion and direct contact with soils.  The Restrictive Covenant for the property will ensure that the integrity of the surface cover will be protected through maintaining the current use of the Site and prevent activities that will expose contaminated soils.


Map showing site location as Okanogan County, WA SITE INFORMATION


View Electronic Documents

Cleanup Site Details Report

Facility Site ID: # 77985367

Cleanup Site ID: 6671

Tonasket, Okanogan County

Status: No Further Action   Get definitions of Status terminology

Jeff Newschwander
Periodic Review Coordinator

Document Repositories:

Central Regional Office
1250 W Alder St
Union Gap, 98903-0009