Bothell Riverside TPH

Ecology has negotiated two new legal agreements called Agreed Orders with the City of Bothell (City), the Potentially Liable Person (PLP) for the Bothell Riverside TPH and Bothell Riverside HVOC Sites. These orders will replace an existing 2009 Agreed Order for the original Bothell Riverside Site.

In November 2019, Ecology hosted a public comment period for these orders, a SEPA Determination, and a Public Participation Plan:


• Agreed Order – Riverside TPH Site: states that contamination was removed through interim cleanup actions in 2010 and 2017, and is in compliance with safe cleanup levels required under Washington’s cleanup law, the Model Toxic Control Act (MTCA). Ecology will remove this Site from its Hazardous Sites List (HSL).
• SEPA (State Environmental Policy Act) Checklist & DNS (Determination of Non-Significance): states that the Cleanup Action Plan for the Riverside TPH Site will not cause environmental damage.
• Agreed Order – Riverside HVOC Site: requires the City to complete a Supplemental Remedial Investigation, Feasibility Study, Interim Action, and draft Cleanup Action Plan for the Site.
• Public Participation Plan: updates a 2017 Plan that describes how Ecology will inform the community about Site activities and opportunities to be involved in the cleanup process.

Ecology received no comments that warranted changes to these documents, and therefore finalized them.  Ecology has also issued a letter of Satisfaction of Order and No Further Action to the City of Bothell for the Bothell Riverside Site.
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The Bothell Riverside TPH (Total Petroleum Hydrocarbons) and HVOC (Halogenated Volatile Organic Compounds) Sites are generally located at NE 180th Street & Woodinville Drive (SR 522) in Bothell. Originally, these were considered “areas” within the overall Riverside Site.

In 2009, Ecology and the City of Bothell entered into an Agreed Order to conduct investigations, develop cleanup alternatives, and perform interim cleanup actions in both areas. Investigations found petroleum contaminants in soil in the TPH area and chlorinated solvents in groundwater in the HVOC area.

In 2019, Ecology negotiated two new Agreed Orders with the City of Bothell (City), the Potentially Liable Person (PLP) for the Bothell Riverside TPH and Bothell Riverside HVOC Sites. These orders replaced the existing 2009 Agreed Order for the original Bothell Riverside Site.

Riverside TPH Site
Operations at the former gasoline service station caused petroleum contamination to get into the soil in the TPH area at cleanup levels higher than allowed under the Model Toxics Control Act (MTCA). In 2010, and again in 2017, the City conducted interim cleanup actions to partially address the contamination. The City excavated the petroleum-contaminated soil and disposed of it at a licensed off-site facility. These actions were successful in removing all contamination from the TPH area. No additional cleanup work is required there.

The new TPH Agreed Order now designates this former area as the Riverside TPH Site. It can now be removed from the Hazardous Sites List while separate work continues in the Riverside HVOC Site.

Riverside HVOC Site
Operations at a former machine maintenance shop are believed to have caused HVOC contamination to enter groundwater in the HVOC area at cleanup levels higher than allowed under MTCA.

In 2013, Ecology and the City agreed to amend the 2009 Agreed Order so that the City could conduct an interim cleanup action to prevent the chlorinated solvents from discharging into the Sammamish River. The City installed six extraction wells to collect solvent-contaminated groundwater and treat and discharge it into the sanitary sewer.

The new HVOC Agreed Order now designates this former area as the Riverside HVOC Site, allowing cleanup work to continue while the TPH Site is removed from the Hazardous Sites List. Under this order the City completed a Supplemental Remedial Investigation, Feasibility Study, Interim Action, and preliminary draft Cleanup Action Plan for the Site. These document are available for public comment from November 21 - December 22, 2022. The City will also continue to implement the 2013 Interim Action.