Terrace Heights Elementary School

Schools in Yakima county 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 Terrace Heights 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 2007, the site was added to Ecology’s Hazardous Sites List with a ranking of “5”. 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.

The East Valley School District conducted an independent remedial action during spring and summer of 2013. The District cleanup plan consisted primarily of capping the contaminated soil with hard surfaces (concrete/asphalt/school) or placing clean soil on top of the existing contaminated soil and establishing a new grass lawn in clean soil. The plan was closely coordinated with the new school construction and included a new irrigation system to maintain the turf grass cover, a clean playground area with engineered wood chips for fall protection, and an environmental covenant to ensure education, care, and protection of the remedial action. The District’s placement of a barrier to prevent human exposure to lead and arsenic is typical of other Ecology projects to address area-wide soil contamination.

Based upon cleanup activities, Ecology has determined the site is no longer a threat to human health and the environment. Ecology issued a no further action determination and the site was removed from the Hazardous Sites List in September 2017.

WAC 173-340-420(2)6 requires Ecology to conduct a periodic review of certain sites every five years. The review is intended to examine the effectiveness of cleanup activities and to assure the continued protection of human health and the environment. For this site, a periodic review is required because an institutional control is required as part of the cleanup action. 
 
Periodic review results

Based upon the site visit conducted in March 2021, the clean soil cap on the site continues to reduce the human exposure pathway to contaminated soils to acceptable levels. 

The cleanup actions completed at the site appear to be 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 covenant for the property is in place and is effective in protecting human health and the environment from exposure to hazardous substances and the integrity of the cleanup action.

Based on this periodic 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.