Manson Elementary School

In 2004, Ecology tested the soil at Manson Elementary School and found lead and arsenic area-wide soil 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.

In 2006, the site was added to Ecology’s Hazardous Sites List with a ranking of “4”. Sites on the Hazardous Sites List are a priority for Ecology, and have completed a Site Hazard Assessment (SHA). A SHA provides information about the environmental risk of the site. Risk is based on the amount of contaminants, how toxic they are, and how easily they can come in contact with people and the environment. Sites are ranked relative to each other on a scale of “1” to “5”; with a rank of “5” being the lowest.

During the summer of 2006, data collected by Ecology showed a distinct boundary between the contaminated soil and the clean native soils. This boundary existed at approximately eight inches below the ground surface across the site. Therefore, Ecology’s cleanup consisted of removing the top eight inches of contaminated soil from the playfield. About 2,000 cubic yards of soil was excavated from the site. The excavated soil was transported to the Okanogan County Landfill in Okanogan, Washington, for disposal.   
 
About 2000 cubic yards of clean topsoil was imported to the site and new grass was established.

Based upon cleanup activities, Ecology has determined the site is no longer a threat to human health and the environment. Ecology made a no further action determination in October 2007. The site has been removed from the Hazardous Sites List.