Sambrailo Land and Cattle Company Property

Two underground storage tanks (USTs) containing diesel and gasoline were used to supply vehicles and trucks for a small agricultural hauling company in Aromas, California. Investigation at the time of tank removal revealed gasoline-impacted soil and groundwater. Using a turnkey approach, impacted soil was excavated to the extent possible and biosparging (air injected into groundwater) was implemented to initiate groundwater restoration. Semiannual groundwater monitoring and sampling was also implemented as requested by the oversight agency. Importantly, it was shown that sparging could be accomplished without vacuum extraction of soil gas due to the enhanced capacity of the unsaturated zone to degrade gasoline concentrations, thus limiting cost. Since activation of the biosparging system, gasoline and benzene concentrations in groundwater have decreased by 88 percent and 96 percent, respectively. The Central Coast Regional Water Quality Control Board is in the process of closing the environmental case.