Extensive soil contamination was discovered during a heating oil underground storage tank site assessment at a residential property. Whatcom Environmental initiated remedial action involving characterizing the type and volume of petroleum contaminated soil (PCS), removing the PCS, bioremediating the PCS onsite, and collecting clean confirmation soil samples to document the completeness of the remedial action. Site soil cleanup levels were set using MTCA Method A and B unrestricted land use and terrestrial ecological screening levels. Approximately 1,725 cubic yards of PCS were treated onsite. Onsite land treatment of the PCS accounted for significant cost savings. The independent remedial action conducted at the site met the requirements set forth in WAC 173-340. No further action was required at the site.