While monitoring of all well sites drilled to observe migrating hydrocarbon from the old leak of underground gasoline storage at Village Food and Fuel (the Shell station) continues, Riverside County Department of Environmental Health has reduced the effort and begun work to restore the site.
Last month, RM Environmental Inc., the contractor, removed the soil vapor extraction wells last used in February 2008. Soil borings a year ago confirmed that further remediation was not warranted.
The September quarterly hydrocarbon samplings were significantly lower than maximum concentrations recorded more than eight years ago.
However, some results were up slightly from the June sampling data. For example, monitoring well no. 1 recorded xylene concentration of 239 micrograms per liter (µ/l) compared to 72.3 µ/l in June. However benzene and methyl-tertiary-butyl ethane were still not detected in this well.
While the MTBE concentration was up slightly in monitoring well no. 4 on the edge of the property, it was down substantially in no. 5, on the opposite side of Ridgeview Drive. This was the lowest reading here since 2010.
Semi-annual groundwater monitoring will continue at the site. Identifying, monitoring and removing hydrocarbons near these sites began in the 1990s.