SITE INFORMATION AND CORRESPONDENCE_FILE 2

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819 N. Hunter Street - 2 - 25 May 201,0 Stockton, San Joaquin Cou. , soil was removed and sent to Kettleman City for proper disposal. On 11 December 2003 site personnel observed a black oily liquid surfacing in the northwest portion of the site. As a result an emergency response was conducted. It was determined that recent rains and recent site grading operations had clipped the fill pipes of a 2,500-gallon heating oil UST previously identified, had caused the UST to fill with rainwater and overflow out of the severed pipe locations. Remedial measures that included water and product removal and additional soil excavation. Approximately 30,000-gallons of water and product were removed and an additional 249+ tons of impacted soil. All impacted media were properly disposed of off-site. Following remedial efforts confirmation samples were collected and additional subsurface investigation that included the installation of numerous groundwater monitoring wells, four on- site around the UST and others off-site for purposes of delineating the VOC problem. Residual soil sampling has shown that all remaining impacts to soil are below any human health and safety concerns for dermal contact of vapor migration into nearby buildings. Further, in the latest groundwater monitoring event, September 2009, there were no petroleum constituent identified above the laboratory detection limit. And a soil vapor survey conducted in October 2007 and in December 2007 did not identify any human health and safety concerns as a result of the UST. GEOLOGY AND HYDROGEOLOGY — Geology beneath the site can be seen in the attached boring log for MW-5A. Depth to water is reported to range between 22 - 30 feet bgs. With a relatively flat gradient (0.0033 in 2009) trending to the north and north-east. SENSITIVE RECEPTOR SURVEY — A sensitive receptor survey identified groundwater in the area is not used for municipal or domestic purposes. Four municipal supply wells within 2-miles of the site have been impacted, by several sources other than the subject site, with VOCs and petroleum hydrocarbons. Groundwater sampling data from the subject site's monitoring well array has shown that no threat to any receptors exists due to the minimal residual impacts from the 2,500-gallon UST. PUBLIC PARTICIPATION - The required public participation comment period was conducted from May 2010 through June 2010. No comments were received during the comment period. DISCUSSION - The information and data accumulated has shown that any residual impacts to soil and groundwater from the former UST are minimal and have attenuated to below human health and safety and water quality concerns and all screening levels based on the San Francisco Regional Board Environmental Screening Levels. Minimal residual impacts that remain in the subsurface in the immediate vicinity of the former UST, and will continue with time to attenuate. This site does not pose a threat to human health and safety or to water quality and should be closed as a low-risk case. All monitoring wells will remain for purposes of investigation and monitoring of the ongoing VOC investigation.