The City of Portland has proposed a new Temporary Alternative Shelter Site, or TASS, on property it owns at 10505 N. Portland Road. The property is owned by the City of Portland and is located in the St. Johns neighborhood adjacent to the Columbia Slough.
According to the city, the proposed TASS is planned to accommodate up to 200 people in tiny home pods and parking spaces for people living in their RV or camper.
Public involvement
DEQ and the City of Portland hosted a public information meeting on April 30, 2024 to share information about the City of Portland's draft Contaminated Media Management Plan, draft Risk Assessment and forthcoming Remedial Action Plan, as well as to answer questions from community members. DEQ recorded the meeting, and you can request a link to the video recording by contacting
Michael Loch.
View the presentation slideshow:
DEQ is committed to providing regular updates with interested community members. If you would like to be added to the email distribution list, please contact
Michael Loch or
subscribe to DEQ's GovDelivery distribution list for this site.
Current status
The site is considered a “brownfield", which is a vacant or underused property where actual or perceived environmental contamination complicates its reuse. DEQ is providing the City of Portland's Bureau of Environmental Services with technical assistance and oversight for investigating, cleaning up and planning safe reuse of the site. Learn more about DEQ's brownfields program by visiting our
brownfields web page or reading our
brownfields fact sheet.
The city submitted several documents for DEQ's evaluation and approval including water quality permits, risk investigation reports and plans to address risks during and after construction. These documents were approved, which allows the city to begin its cleanup and redevelopment activities. One of which is asphalt paving that is scheduled for late-August 2024 to create a barrier between any underground contamination and future users of the planned TASS. Read more about these documents and how their plans are protective of human health and the environment below.
DEQ issued the City of Portland a water quality permit called a Water Pollution Control Facility permit in preparation for construction work at the site. This permit alone did not allow the City of Portland to do any ground disturbing work at the site. A DEQ-approved Contaminated Media Management Plan was required for that work can begin.
DEQ issued the city's 1200-CA stormwater construction general permit when the Contaminated Media Management Plan was approved. The permit puts into place stormwater management and erosion control requirements during construction. DEQ required the city to obtain this permit in preparation for doing construction work at the site, but as mentioned above, the city was required to have a DEQ-approved Contaminated Media Management Plan before ground disturbing work can begin.
DEQ approved the City of Portland's Contaminated Media Management Plan, which provides site-specific information and guidance regarding the management of contaminated media that may be encountered during construction activities. This approval allows the City of Portland to begin ground disturbing activities at the site.
The City of Portland prepared a Risk Assessment that evaluated potential risks to occupants and workers on the site. The Risk Assessment informed proper cleanup and reuse planning. The Risk Assessment was revised to incorporate comments from DEQ and recent soil vapor sampling results. The final Risk Assessment was approved in August 2024.
Soil vapor is the air that exists between soil particles. It can become contaminated when chemicals in the ground evaporate. Contaminated vapors can travel through the soil and enter buildings or outdoor air. The city tested for soil vapor in late-April 2024 and DEQ received the final report on July 10, 2024. The results indicate that contaminant concentrations in soil vapor do not pose a health risk for future occupants and workers of the site.
The study also found underground methane at elevated levels. Methane is a colorless and odorless gas. It is relatively non-toxic but can pose a flammable or explosive hazard if allowed to accumulate in poorly ventilated spaces or act as an asphyxiant if allowed to displace oxygen in the air.
Methane was detected in underground soil at the site, but no meaningful levels were detected in the outdoor air. The city and DEQ have developed a safety plan for workers who will be doing underground construction activities on the site in consultation with a certified industrial hygienist. The city included a long-term plan to address the methane and any potential risks in its final cleanup and redevelopment plan that DEQ evaluated and approved. The city also included these results in its final Risk Assessment.
The city developed a cleanup and redevelopment plan for the site, also called a Remedial Action Plan. This plan uses the conclusions from the Risk Assessment to address any risks at the site.
The objectives of this plan are to:
- Eliminate human exposure to potentially contaminated soil.
- Minimize contact of potentially contaminated soil by construction workers.
- Minimize potential impacts to groundwater, surface water, sediment from infiltration and surface water runoff.
- Properly manage any contaminated soil encountered during construction.
The protective measures to achieve these objectives include:
- Constructing a 1-foot-thick protective cap across the site consisting of clean base rock topped with asphalt to prevent contact with surface soil that could contain contamination.
- Placing a demarcation layer consisting of a geotextile fabric at the base of the protective cap to mark the boundary between potentially contaminated soil and the overlying clean cap.
- Managing stormwater from the site to prevent impacts to nearby properties and the Columbia Slough.
- Installing ventilation and monitoring controls to ensure methane is not accumulating at unacceptable levels in structures and enclosed spaces.
- Implementing an Inspection and Maintenance plan to ensure the cleanup and redevelopment actions continue to meet the human health and environmental protection objectives.
DEQ approved this document in August 2024. DEQ's approval allows for construction of the cleanup elements to occur. The city plans to begin asphalt paving and other site development activities in late-August 2024.