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Superlon Site

    Project Overview

    The PIONEER Project Team is conducting a Remedial Investigation (RI) at the Superlon Plastics site, a former lead-arsenate manufacturing facility that is located in the Port of Tacoma. The Tideflats were filled and developed in the early 1900’s. Fill materials in the general area include dredge materials, native soils, and various types of waste and debris, including materials believed to be Occidental chemical sludge, Asarco slag, and U.S. Gypsum rock wool. The Superlon site shows evidence of historical filling activities; however, the nature and origin of all of the fill material is unknown.

    The PIONEER Project Team has been highly effective at developing work plans, conducting investigations, performing interim actions, developing and implementing a Cleanup Action Plan strategy, and achieving cost recovery at the Superlon site.

    Our Solution

    All FS work at the Superlon site is being conducted with future land use in mind. A conceptual land use plan was developed to support the development of a strategic plan that is focused on true and anticipated risks, rather than unrealistic, unrestricted land use. This approach is very effective for establishing remediation levels.

    During Phase I of the RI, a fine-grained light grey material with high levels of VOCs was identified. A fingerprint analysis was conducted, and the results matched Ecology’s fingerprint for the Occidental Chemical waste water sludge. The comparison was documented and Occidental Chemical was contacted. A Work Plan was created for (1) excavating and disposing this material, and (2) documenting the excavation, waste characterization, and disposal process with future cost recovery and potential litigation in mind. Once the Work Plan was approved by Ecology, Occidental Chemical was contacted to inform them of our actions and invite them to review our Work Plan and oversee the excavation process. Meetings were held on site during the excavation process and input was requested from an Occidental representative. A special effort was made to document all of the work and associated costs, which included a thorough accounting of costs, disposal manifests, and field notes, and were included in a final report for Ecology and Occidental Chemical.


    The RI is being completed in phases to decrease cost and increase efficiency. Phase I involved sampling the site on a 75-foot grid system to a depth of 15 feet (Model Toxics Control Act (MTCA) point of compliance for soil). Data was evaluated to determine the nature and extent of hazardous substances in soil, sediments, groundwater, and surface water, and identify any data gaps that needed to be addressed to develop a risk assessment and feasibility study. Phase II involved collecting data to address the identified data gaps and installing a groundwater monitoring well network that determined the groundwater conditions in the first continuous water aquifer. Additional soil data was collected during Phase II to fill remaining data gaps. Groundwater results suggested the need for the assessment of groundwater conditions in the immediate aquifer. A Phase III Work Plan was developed to install monitoring wells in this aquifer. Phase III will be completed in the summer of 2012. All of this work was designed to address Ecology’s requirements.

    During the investigation stage, the PIONEER Project Team completed three interim action programs that required the management and disposal of hazardous and problem wastes. These wastes ranged from building materials to soil/fill to Occidental Chemical waste water sludge, and were impacted with high/hazardous levels of lead and arsenic (and in the case of the Occidental Chemical waste water sludge, high levels of VOCs). The disposal process included stockpiling and testing the material for designation, creating waste profiles, loading the trucks for transportation, and coordinating with the landfill and the transport companies. The more difficult, but successfully-accomplished tasks included handling and stockpiling extremely wet, clay-rich and fine-grained soils and sludge. Ecology was present during these tasks and provided oversight.