Pacific Power & Light Union Gap Substation

The site is the location of a electrical substation facility located at the intersection of the Burlington Northern Railroad and Ahtanum Road, in Union Gap. The site consists of various transformers and power lines typical of an electrical power substation.
 
A large power transformer had a mineral oil leak estimated at 250 gallons. About 100 gallons was pumped from the transformer vault. About 27 cubic yards of soil was removed immediately adjacent to the transformer. During a conversation between Ecology and the consultant, it was reported that a portion of the contaminated soil was still present underneath the transformer vault after the excavation.

Soil samples from the excavation were non-detect for PCBs. Soil samples from the temporary groundwater well investigation were also non-detect for PCBs as well. Soil sheen testing was negative for hydrocarbons during the temporary groundwater sampling as well.  However, no sheen testing or Total Petroleum Hydrocarbons (TPH) soil analysis was conducted inside of the excavation.

Groundwater samples from temporary wells were also obtained from the vicinity of the transformer and the laboratory analyzed for TPH-D and PCBs. All groundwater samples were non-detect for PCBs, however two groundwater samples exceeded the Model Toxics Control Act (MTCA) Method A cleanup standard for oil and diesel.