| On 4/20/2026, the potential presence of impacted material(s) was identified via hydrocarbon odor and/or hydrocarbon staining during decommissioning activities at the Pierce Unit Central Tank Battery. Samples DL01-01, DL02-01, DL03-01 were collected from the AST dump line. The volume of potentially impacted material(s) is not currently known. Initial soil sampling is underway to determine whether any constituents are present at levels in excess of Table 915-1 standards. Groundwater was not encountered during decommissioning activities. This location is within the Mule Deer Severe Winter Range, Mule Deer Winter Concentration Area, and Pronghorn Winter Concentration High Priority Habitat; and is also with 300 feet of waters of the state. Final analytical results from initial soil sampling will be included on a Supplemental Form 19. |