Portac Inc Tacoma

Ecology finalized the Cleanup Action Plan to address contamination at the Site and signed a legal agreement (AO DE 15816) with the Port of Tacoma (port) to implement the cleanup plan. The port is the potentially liable person (PLP) responsible for cleaning up the Site. 

A fact sheet briefly summarizes information about the cleanup action plan. 

Ecology held a public comment period from April 22 to May 23, 2021, inviting comments on cleanup documents including:

• Remedial Investigation & Appendices.
• Feasibility Study and Feasibility Study Addendum.
• draft Cleanup Action Plan.
• Agreed Order DE 15816 with the port to implement the Cleanup Action Plan.
• State Environmental Policy Act (SEPA) Determination of Non-Significance.

We received two sets of comments during the comment period. The Responsiveness Summary provides our response to comments. 

Ecology made no changes to the documents based on the comments received during the comment period. 

Ecology staff is overseeing the project to ensure that human health and the environment are protected during construction.

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The Site is about 52 acres located in the Tacoma Tideflats next to Wapato Creek, which flows into the Blair Waterway and Commencement Bay. From 1974 to 2009, Portac Inc. leased the property from the Port for use as a log yard and sawmill. In 2008, Portac Inc. removed the sawmill. Now the Site is a paved parking lot for cars and trucks.

The site became contaminated in the 1970s when slag (waste) from the former Asarco smelter was brought to the Site for roads to support heavy equipment. The slag contained arsenic and other metals. Contaminated stormwater ran off the site into Wapato Creek. To prevent this contamination, a concrete cap was constructed in the log yard to cover soil containing arsenic. A stormwater collection system was built to control movement of stormwater off the cap.

While the sawmill was operating, a wood preservative containing pentachlorophenol (PCP) was used to treat lumber. When Portac Inc. removed the sawmill, PCP was found in soil and groundwater, and arsenic and petroleum contamination was found in soil. These areas were excavated, the excavations backfilled with clean soil, and the contaminated soil was properly disposed.

Decreasing PCP concentrations are still present in one monitoring well located in the area where lumber was dipped into a tank containing PCP. The amount of PCP in groundwater is decreasing because of biological activity in the soil. 

The Cleanup Action Plan is driven by these objectives:

• Log Yard Area--Eliminate exposure of stormwater and surface water to arsenic-contaminated soil and groundwater.
• Sawmill Area--Eliminate exposure of surface water to PCP-contaminated groundwater.

The plan describes the stormwater collection system will be improved and a permeable reactive barrier will be installed next to Wapato Creek on the northwestern corner of the site. The barrier reduces arsenic in groundwater as it moves through the barrier.

Groundwater will be monitored downgradient of the barrier to ensure the barrier's effectiveness and show that PCP contamination continues to decrease.

When the site is ready for redevelopment, a new improved cap will be constructed under a separate agreed order.   

Follow-up

If the cleanup actions are not successful, then additional actions will be used to protect people's health and environment.

Environmental Covenant

An environmental covenant on the property will be filed in county records. Among several restrictions on the Site, land use will be limited to industry.