Peshastin Dryden Elementary School

Soil beneath the grass on the playgrounds at the Peshastin-Dryden Elementary school was contaminated with area-wide lead and arsenic soil contamination.

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 2008, Ecology conducted a cleanup and placed all contaminated soils under a geotextile fabric barrier. Then, six inches of clean topsoil were placed on top on the barrier fabric. This cleanup method, referred to as capping, is cost-effective and prevents human exposure to contaminated soil. Following cleanup, an environmental covenant was recorded for the property with the Chelan County Assessor in 2010.

In February 1993, two underground storage tanks (USTs) were removed from the Bus Garage area. Petroleum contaminated soil excavated to a depth of 27 feet below ground surface. A community well located 163 feet from the UST excavation was sampled in 1993 and reported not to have been impacted. Because some contamination was left onsite adjacent to the building foundation to protect the existing structure, Ecology required a restrictive covenant for a no further action determination for this release. The covenant was recorded in June 2012.

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