CHS Auburn

CHS Auburn site is a gasoline sales and bulk tank facility located at 238 8th Street SE in Auburn Washington. From approximately 1920 to 1985, Valley Supply Co-op operated a gasoline distribution business at this site. Cenex purchased the facility from Valley Supply in 1985. Cenex and later CHS, Inc. continued business operations at the site, including bulk and retail sales and operation of above-and under-ground bulk and retail petroleum storage tanks.

Contamination, primarily petroleum related products, was confirmed in soil and groundwater at the site in 1994. Emergency actions were taken to cleanup the site, but in order to fully characterize the contamination and evaluate possible cleanup options, additional study was required.

CHS has completed a Remedial Investigation and Feasibility Study (RI/FS). This study determined the nature and extent of remaining contamination and evaluated possible methods to clean up the site. The identified chemicals of concern in soil and groundwater are petroleum hydrocarbon compounds (gasoline, diesel, oil, benzene, toluene, ethylbenzene, and xylenes) from a leaking gasoline pipe. They also prepared a Cleanup Action Plan describing how they will clean up the site.

Remedial activities have been ongoing since 1994, with one groundwater remediation system currently active. The contaminated groundwater plume has reduced in size since 1994. The cleanup will address the remaining soil and groundwater contamination in a targeted area of the site using focused air sparging, monitored natural attenuation, and institutional controls. The targeted area is located south of the intersection of 7th Street SE and Auburn Way S, and along the southwest side of the Auburn Way S. right-of-way.

Ecology and CHS, Inc. have now entered into a legal agreement called a Consent Decree that will require CHS to complete the cleanup. A public comment period was held and no comments were received. The Final Cleanup Action Plan is now available.