North Omak Elementary

North Omak Elementary School is located on former orchard land and was subjected to historical pesticide applications resulting in area-wide soil contamination. In 2005, Ecology staff tested the soil at the Site and found lead and arsenic contamination exceeding state cleanup levels.

Area-wide soil contamination is defined as contamination above state cleanup levels that is dispersed over a large geographic area. The soil contamination in this case is a result of central Washington’s orchard industry. Much of the region consists of current or former orchard land, where long-term pesticide application has taken its toll. Lead arsenate, a pesticide commonly used between the years of 1905 and 1947 to control the codling moth, has been identified as the primary source of increased lead and arsenic concentrations.

Due to their chemical structure, lead and arsenic tend to bond with soil particles and often remain at or near ground surface level for decades, creating an exposure pathway through inhalation and/or ingestion.

Although lead and arsenic are naturally occurring elements, elevated concentrations have been proven to have a negative impact on human health. Young children are generally more susceptible than adults, which is why Ecology has focused remediation efforts on schools.

During the summer of 2006, Ecology staff managed a cleanup at the Site designed to reduce or eliminate the lead and arsenic contamination.  It involved three major steps: 1) excavation of contaminated soil for disposal at a permitted landfill, 2) placement of geotextile fabric, and 3) import of clean topsoil. New seed or sod was placed down to establish grass.

Ecology staff verified through confirmational sampling that the contamination had been either removed or covered with a layer of clean topsoil.  An environmental covenant was recorded for the property with the Okanogan County Auditor. The purpose of the environmental covenant is to provide a permanent legal record of the contamination that remains on the property, and to prevent activities at the site that might disturb or damage the soil cap.

Based upon cleanup activities and the recording of a restrictive covenant, Ecology has determined the site is no longer a threat to human health and the environment. 

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.

Results of April 2013 Periodic Review

The cleanup actions completed at the Site is protective of human health and the environment.  Soils cleanup levels have not been met at the Site; however, the cleanup action is determined to comply with cleanup standards at the time of the action, since the long-term integrity of the containment system is ensured and the requirements for containment technologies have been met. 

An environmental covenant has been recorded for the Site that restricts activities that may expose contaminated soil, and notifies future property owners of contamination remaining at the Site.

Portions of the field where the clean soil cap has been exposed beneath play areas or damaged turf should be repaired to prevent exposure to contaminated soils.

Based on this periodic review, the Department of Ecology has determined that the requirements of the environmental covenants are being followed.  No additional remedial actions are required by the School District, but maintenance of the field should be conducted.  It is the School District’s responsibility to continue to inspect and maintain the Site to ensure that the integrity of the cap is maintained.