Tosco Bainbridge Island Bulk Plant 1784

The site is currently in the Remedial Investigation stage of the cleanup process. Additional soil and groundwater sampling is planned to define the extent of soil and groundwater contamination at the Site.

The Site was first developed as a heating oil bulk storage facility.

The Site included:

• two 10,000-gallon and two 4,000-gallon above ground storage tanks (ASTs),
• pumping station
• overhead loading rack
• detention pond

In 1997, the ASTs, loading rack, pumping station, and associated piping were removed following the sale of the Property.

As part of the property sale in 1997, soil contaminated with diesel-range total petroleum hydrocarbons (TPH-D) was discovered around the loading rack, ASTs, and pumping station.

In 1999, additional Site characterization work was completed. As a result, gasoline-range TPH (TPH-G) was found in the soil near the ASTs and at the detention pond to the south. Groundwater samples in the vicinity of the ASTs also contained TPH-G and TPH-D above cleanup levels.

In June 2000, soil contaminated with TPH-G and TPH-D was excavated from the area around the detention pond to a maximum depth of 6 feet below ground surface (bgs). Approximately 90 cubic yards of contaminated soil were excavated and removed from the Property. Confirmation samples collected from the bottom and sidewalls of the excavation did not contain TPH-G or TPH-D above the cleanup levels.

In June 2001, soil contaminated with TPH-G and TPH-D was excavated from the former AST and loading rack area to a maximum depth of 12 feet bgs. Approximately 400 cubic yards of soil was excavated and removed from the Property for disposal. Except for one sidewall sample collected from the east sidewall of the excavation. Soil samples collected from the bottom and sidewalls of the excavation did not contain TPH-G or TPH-D above the cleanup level.

Following the completion of the remedial excavation, a perforated PVC piping was installed in the bottom of the excavation to aid in treatment of contaminated groundwater. The piping system is used to inject nutrients and oxygen-releasing compounds into the groundwater to aid in natural breakdown of petroleum hydrocarbons.

Five groundwater monitoring wells were installed on the Site in 2001. Depth to groundwater at the site is approximately 3 to 7 feet bgs.

Groundwater flow at the Site is directed south toward Eagle Harbor. Groundwater samples collected from the monitoring well network contained concentrations of TPH-G, TPH-D, and TPH-O above the cleanup level.

Following the remedial excavations and groundwater treatments, concentrations of petroleum hydrocarbons have decreased in Site monitoring wells. Monitoring and characterization work is continuing to define the current extent of contaminated soil and groundwater.

The Model Toxics Control Act (MTCA) is Washington’s environmental cleanup law. It provides requirements for contaminated site cleanup and sets standards that protect human health and the environment. Ecology enacts the MTCA and oversees cleanups.

​The MTCA site cleanup process is completed in steps over a variable timeline.

What's In My Neighborhood shows contamination cleanup sites in Washington state. Ecology works to clean up these sites to protect the health of people and the environment. Cleanups are construction projects that remove, treat, or contain potentially harmful substances.

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Counties: Island, King, Kitsap, San Juan, Skagit, Snohomish, and Whatcom
Email: nwroerts@ecy.wa.gov
Phone: 206-594-0000

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This site is in our Voluntary Cleanup Program, which provides technical help to owners of contaminated sites.

Voluntary Cleanup Program customers pay fees to cover our costs for technical help and reviewing cleanup reports. Sites in this program must meet the same cleanup standards as sites Ecology manages under legal orders.