Success Stories

Underground storage tank excavation in Auburn, CA

This site is currently an operating retail gas station located just west of Interstate 80. Three underground storage tanks (USTs) were removed from the Site in December 1998, and six soil samples were collected from beneath the tanks.  Analytical results showed that the soil beneath the tanks had been impacted by petroleum hydrocarbons. During the subsequent over-excavation of hydrocarbon-impacted soil, approximately 630 cubic yards were removed and transported off-site.

In April 2000, under the direction of the Regional Water Quality Control Board,  six soil borings were advanced, and four were converted to groundwater monitoring wells.  Groundwater monitoring and reporting continued on a quarterly basis from 2000 until October  2004, when the RWQCB directed the proper abandonment of the site’s four groundwater-monitoring wells in preparation of a finding of No Further Action. In late 2004, E₂C Remediation was selected to perform environmental services on behalf of Toms Sierra Company, Inc. dba Sierra Energy. E2C resumed groundwater monitoring for the Second, Third, and Fourth Quarters of 2005 at the request of the RWQCB.  During this time, relatively low to non-detectable levels of petroleum hydrocarbons were observed in groundwater samples.

E2C prepared and submitted a Workplan in January, 2006, for the installation of four monitoring wells at the direction of the RWQCB for additional groundwater assessment.  Another RWQCB directive from June, 2006 requested that E2C submit a workplan for a soil gas survey in order to determine if there would be any risk to human health from shallow contamination. In May 2007, eleven soil gas samples were collected and all eleven 11 were reported as non-detect for all contaminants, except two samples, which reported MtBE reported at 0.11 and 0.3 parts per billion by volume (ppbV). Based on the low levels of contaminants found in soil samples, soil-vapor samples and groundwater samples, E2C recommended that the site be considered for regulatory closure in March 2008. In December 2008, the RWQCB concurred with E2C’s recommendation and issued a No Further Action Required directive for regulatory closure as a low risk site.