The South Rivergate Pond (SRP) is a small, approx. 3-acre pond and wetlands area in Portland, Oregon, located in the South Rivergate Industrial Corridor between the Willamette River and the Columbia Slough. It is bordered by two large electrical substations and a railroad spur, and overflows into the Columbia Slough, a waterway of concern to the State due to historic contamination and recent cleanup efforts along the slough and its watershed. Due to concern and a request for assistance by the state, an EPA Site Investigation (SI) of the SRP was conducted in 2018/2019. As a result of the SI, EPA determined that levels of two PCBs, several metals, pesticides, and semi-volatiles were elevated above ambient/ background levels and Oregon Lower Columbia Slough Risk Screening Values (SLVs).
Using sediment sample data and information from the SI, an On-Scene Coordinator (OSC) Removal Site Evaluation (RSE) was then conducted in 2019/2020 to determine risks to public health as well as the potential for a Time-Critical Removal Action (TCRA). Sediment analytical data were compared to EPA Regional Screening Levels (RSLs), EPA Removal Management Levels (RMLs), and Oregon Risk-Based Concentrations (RBCs) for residential soil as a conservative approach for public health risk.
In coordination with EPA toxicologists, and in considering federal and state sediment contaminant risk levels as well as exposure routes to human health, the OSC determined that a Time-Critical Removal Action was not warranted. However, further action by ODEQ and EPA's Remedial and Site Assessment Programs may consider further action at the site.
