Portac Inc Tacoma
4215 Sr 509 E Frontage Rd, Tacoma, WA 98421-3998


Cleanup Documents and SEPA Determination 

Ecology invites comment on the following draft documents for this Site:

Information about the Site and the comment period can be found in the fact sheet.

The Potentially Liable Person (PLP) responsible for cleanup is the Port of Tacoma (Port). 

Contamination at the Site includes arsenic in soil, surface water, and groundwater. Pentachlorophenol (PCP) has been found in soil and groundwater. Cleanup actions are required at the site to protect human health and the environment. 

If you wish to view electronic documents related to this Site, click on the "View Electronic Documents" link on the right under "Site Information."

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Portac Inc. cleanup site is located at 4215 SR 509 E, Tacoma
Please click on the photo for a larger view


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 draft Cleanup Action Plan (dCAP) is driven by these objectives:

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

Log yard Area

The cleanup includes two phases. Phase 1 begins after the Port finalizes design work and permitting. Phase 2 begins later, when the site is ready for redevelopment.  

Phase 1:

  • Improve the existing stormwater system to prevent arsenic-contaminated water from moving into Wapato Creek.
  • Construct a permeable reactive barrier along the boundary of the log yard next to Wapato Creek that reduces arsenic in groundwater as it moves through the barrier. 
  • Monitor stormwater and groundwater to make sure arsenic is not moving from the log yard into Wapato Creek.

Phase 2:

  • Construct a new, improved cap to cover the arsenic-contaminated soil to reduce stormwater from seeping through the cap into the groundwater.
  • Install a watertight stormwater system to reduce the amount of water contacting arsenic-contaminated soil. 
  • Monitor groundwater to make sure these actions are working. 

Sawmill Area

  • Monitor PCP in groundwater near the dip tank area to make sure contamination continues to decrease.


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.


For more information about cleanup sites in the neighborhood and throughout Washington, go to:

These tools also show completed cleanups.


Map showing site location as Pierce County, WA SITE INFORMATION


View Electronic Documents

Cleanup Site Details Report

Facility Site ID: # 1215

Cleanup Site ID: 3642

Tacoma, Pierce County

Status: Cleanup Started   Get definitions of Status terminology

Comment Period:
APRIL 22, 2021 - MAY 23, 2021

Andrew Smith
Site Manager
(360) 407-6316

Nancy Davis
Public Involvement Coordinator
(360) 407-0067

Document Repositories:

Southwest Regional Office
300 Desmond Dr SE
Lacey, 98503-1274