Model Remedy Implementation for Historical Orchard Lands

MFA was the lead technical consultant for the Legacy Pesticide Working Group (LPWG), which was convened by the Washington State Department of Ecology (Ecology) to assist in developing recommendations on addressing concerns related to potential human health risks associated with residential development on former orchard properties in Central and Eastern Washington. MFA provided scientific, engineering, land use planning expertise, and communications support associated with the application of the Model Toxins Control Act, the State Environmental Policy Act, and local land use regulations. The MFA 2021 LPWG final report (Recommend Approach for Managing Lead Arsenate Legacy Pesticide Contamination on Historical Orchards in Central Washington) provided guidance on elements that were incorporated into the Ecology July 2021 final model remedy (Model Remedies for Cleanup of Former Orchard Properties in Central and Eastern Washington). The model remedy created four preapproved approaches for the cleanup of historical orchard lands that commonly show elevated lead and arsenic concentrations from historical pesticide use.

The Cameo Development, a 20-unit single family home subdivision, served as a pilot project for the new model remedy. MFA’s interdisciplinary team helped Chelan County and the developer choose the appropriate model remedy and troubleshoot the new process. The project allowed the team to develop tools, document typical project costs, and identify lessons that were integrated into the final model remedy. As a result, cleanup was conducted at the site using a combination of clean soil capping and asphalt hard capping. The tools developed include factsheets, development agreements, and model forms that have been integrated into Ecology’s resource website to help guide future development projects on historical orchard lands.