Gilbert Elementary School

Schools in the Yakima School District were sampled for lead and arsenic contamination as part of Ecology’s Area-Wide Soil Contamination Project. Soil beneath the grass of the playground at the elementary school contains lead and arsenic; sampling and analysis indicates that contamination exceeds 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 “3”. 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 2009, Ecology conducted a cleanup and placed all contaminated soils under a geotextile fabric barrier. Then, eight 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 Yakima County Assessor. 

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. Ecology made a no further action determination in April 2011. The site has been removed from the Hazardous Sites List.

Ecology conducts periodic reviews every 5 years at sites that have 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

• The cleanup actions completed at the site are protective of human health and the environment.
• Soil cleanup levels have not been met at the site; however, the cleanup action is determined to comply with cleanup standards under WAC 173-340-740(6)(f), since the long-term integrity of the containment system is ensured and the requirements for containment technologies have been met.
• The environmental covenant for the site is in place and will be effective in protecting public health and the environment from exposure to hazardous substances and protecting the integrity of the cleanup action.

Based on this five-year review, Ecology has determined that the requirements of the environmental covenant are being followed. No additional remedial actions are required by the property owner. It is the property owner’s responsibility to continue to inspect the site to assure that the integrity of the cap is maintained.