The Annual Reports regarding activity at the underground fuel tanks in Idyllwild and Pine Cove were submitted to the Riverside County Department of Environmental Health last month. Monitoring at both sites indicates gradual improvement of contaminant concentrations.

Idyllwild — Shell Station
Since March 2002, Sandlin and Sons, has been conducting quarterly groundwater monitoring on behalf of the owners and submitting results to the county for oversight.

Although the concentrations of total hydrocarbons, benzene and toluene were higher in March than 2011, the recorded level of methyl-tertiary-butyl ether (MTBE), which has historically been the highlighted chemical, was not recorded at the station site. No MTBE was detected at monitoring well no. 4 for the first time since 2009.

Concentrations of MTBE were recorded at three other sampling sites, including one just south of the Chevron station. But at 8.14 micrograms per liter (μg/L), this was the first measurable recording since March 2011, which was 1,130 μg/L.

MTBE was found in two other well sites, but concentrations were more than one-third of the 2011 levels and substantially less than the peak in 2009.

Nevertheless, the report recommends investigation of the Chevron site to determine the extent of a possible hydrocarbon plume, which may be drifting south and across Highway 243 from the Shell station.

Station owner John Friemoth confirmed the state has approved the site for investigation, but funding has yet to be allocated for the work.

Pine Cove — Pine Cove Market
January readings of hydrocarbons were detected in only well no. 2. Some results such as total hydrocarbon, benzene and ethylbenzene were higher than August 2011, but toluene and xylene had declined.

“Based on the results of current and previous groundwater monitoring and sampling results, concentrations of petroleum hydrocarbons in groundwater have been assessed in all directions from the source area. The plume of dissolved phase petroleum hydrocarbons appears to be stable and restricted to the immediate vicinity of well MW2.

“Frey Engineering recommends conducting a Sensitive Receptor Survey and preparing a site conceptual model and request for no further action for the site during the second quarter 2012,” wrote Sawyer Jones, the senior staff environmental scientist, and Joe Frey, the certified engineering geologist.