DTSC is proposing to approve a Removal Action Workplan (RAW) pursuant to authority granted under Chapter 6.8, Division 20, CA Health and Safety Code (H&SC). The objective of the RAW is protect human health and the environment by removing contaminated soils on the Morse Park Site. DTSC is overseeing cleanup at the Site under a Voluntary Cleanup Agreement (Docket No. HAS-VCA 11/12-001) with the City of Sunnyvale.
From the mid-to-late-1970s until 2008, various businesses, including machine shops and metal fabrication facilities, operated in five multi-tenant buildings on the Site. Prior to the 1970s, the Site was an agricultural orchard that used various pesticides. Investigations have found DDD, DDE, DDT, and lead and arsenic in the soil.
The upper end of the range of naturally-occurring background levels is established by the RAW as the cleanup goal for arsenic, and was calculated to be 17 milligrams per kilogram. None of the other chemicals found during the investigation (DDD, DDE, DDT, and lead) had soil concentrations that were above the CA Human Health Screening Levels for residential (unrestricted) land use, so they do not pose a significant risk, arsenic is the only chemical that needs to be remediated.
The proposed clean-up project will excavate soil approximately 16,700 tons of arsenic-contaminated soil and transport it to a disposal facility that accepts non-hazardous waste (Class II). Control measures to minimize dust, noise, and traffic impacts are included in the RAW. Excavation is expected to take up to 10 weeks and remove 2 feet of soil. The City of Sunnyvale will backfill the Site after DTSC certifies the completion of the clean up.