Facility Site ID: 628 Cleanup Site ID: 1081

  • Site Status

  • Cleanup Started

Site Background

The Aluminum Recycling Trentwood site is across the Spokane River from the Spokane Valley Mall. Union Pacific Railroad (UPRR) is responsible for site cleanup.

Between 1979 and 1984, the site was used to process and store aluminum. “Primary” and “secondary” aluminum processing was used. The processing created white and black dross as byproducts. When processing ended, two stockpiles of dross were left at the site.

Around 1986, UPRR removed one stockpile and put it in a landfill. In 2017, UPRR removed about 360 cubic yards of the other stockpile to test using it as a raw material in cement production. About 57,000 cubic yards of the second stockpile is left and covers nearly 4 acres.

The remaining stockpile covers an area that includes two neighboring properties. The neighboring properties are owned by Pentzer Venture Holdings II Inc. (Pentzer) and the Washington State Department of Transportation. Pentzer is also legally responsible for cleanup, but UPRR is taking the lead.


White dross contains high aluminum content, and black dross contains high levels of chloride, fluoride, and nitrate.


In 2009, Ecology signed an Agreed Order with UPRR to document the extent and locations of dross contamination (remedial investigation) and evaluate cleanup options (feasibility study) for the site.   

In 2012, Ecology held a public comment period for UPRR's Remedial Investigation and Feasibility Study. We published our responses to comments.

In 2017, UPRR proposed to excavate approximately 360 cubic yards of the mixed waste stockpile to test its use in a recycling process. Ecology held a public comment period for the State Environmental Policy Act checklist we used to determine whether the test would have negative effects on people or the environment and our Determination of Non-Significance. We didn't receive any comments. The results of this test were published in the revised Feasibility Study.

To facilitate a property sale that will allow land to be developed by the community, dross that eroded onto neighboring properties was excavated in spring 2020 and placed back on the large pile. 

From June 9 through July 23, 2021, the draft Cleanup Action Plan, enforcement order, scope of work and schedule, and revised Feasibility Study were available for public comment. In the Cleanup Action Plan, Ecology proposed that UPRR dispose stockpiled aluminum-processing byproducts and contaminated soil at a permitted landfill and cap remaining contaminated soil. The enforcement order is a legal document requiring UPRR to complete the cleanup. Ecology and UPRR could not reach an agreement during the agreed order negotiations, so we issued an enforcement order. The order includes a scope of work and schedule for completing the cleanup. We responded to three sets of comments following the comment period, and modified the Cleanup Action Plan and enforcement order as a result of comments.
Legal 2
Document Title Document Date Document Type
Enforcement Order: Aluminum Recycling Trentwood CAP 9/17/2021 Enforcement Order
Aluminum Recycling Trentwood AO Remedial Actiom 8/20/2009 Agreed Order
Public Information 6
State Environmental Policy Act 2
Technical Reports 9
Document Title Document Date Document Type
EDR main text & Appendix A 5/17/2022 Engineering Design Report
EDR Appendices E & F - Compliance Monitoring Plan & Inspection and Maintenance Plan 5/17/2022 Engineering Design Report
EDR Appendices B & C - Construction Quality Assurance Plan & Design Calcs 5/17/2022 Engineering Design Report
EDR Appendix D - Health and Safety Plan 5/17/2022 Engineering Design Report
Cleanup Action Plan: Aluminum Recycling Trentwood 9/10/2021 Cleanup Action Plan
Revised Feasibility Study: Aluminum Recycling Trentwood 6/9/2021 Feasibility Study
Scope of Work and Schedule for Aluminum Recycling Trentwood CAP 6/9/2021 Scope Of Work
Remedial Investigation/Feasibility Study Report Final 9/6/2012 Remedial Investigation / Feasibility Study
Aluminum Recycling Trentwood - Site Hazard Assessment 2/15/2008 Site Hazard Assessment Report
There may be more documents related to this site. To obtain documents not available electronically, you will need to make a public records request.

Places to see print documents

  • Eastern Regional Office
    N 4601 Monroe St
    Spokane, 99205-1265
    Please schedule an appointment to view print documents at this location.
  • Spokane Valley Public Library
    12004 East Main
    Spokane Valley, 99216
    This location may only have print documents available during open comment periods.

Contaminants 2

Contaminant Type
Surface Water
Metals - Metals - Other C
Other Contaminant - Conventional Contaminants, Inorganic B
Confirmed Above Cleanup Levels
Below Cleanup Levels
This contaminant list was based on our best information at the time it was entered. It may not reflect current conditions at the site.