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Gene Gabbard Inc. - 2 - 12 October 2004 640 El Dorado Street, Stockton, San Joaquin County • Potential off-site source of PCE in¢roundwater. Pat said that a drycleaners (currently Unifirst Corporation, 819 Hunter St., which is not a SLIC site) is located across street and has been in business over 50 years, and that sewers were probably used for disposal of PCE and leaked,thereby creating the groundwater problem at their site. Actually the drycleaners is located more than one block away at 844 EI Dorado Street. Pat asked Nuel for process to get the drycleaner investigated/named as RP for PCE. Nuel stated that SJCEHD is only involved in UST cases; and that Pat would need to speak to the Regional Board or the Department of Toxic Substances Control about a PCE spill site. I gave a brief process for naming a drycleaners as an/RP: Your investigation report provides evidence (data and site conceptual model) to support your claim that the drycleaner is a discharger and you were not responsible for the PCE in groundwater; SJCEHD and RWQCB review the report and concur that your UST did not contribute enough PCE mass to account for the distribution in groundwater, and additional offsite source(s) have been identified; SJCEHD refers the drycleaners as a non-UST case in writing to RWQCB; I refer(memo)to RWQCB Site Cleanup Unit for inclusion into SLIC database; and the drycleaners site is accepted/rejected as SLIC case. John requested input on possible passive soil gas survey. . I noted that they are difficult to do in busy street(potential GoresorberTM damage/cross-contamination from traffic) GoresorbersTM are highly susceptible to air pollution if the surface seal is compromised during a test—you could get a potential false positive for soil gas vapors, including petroleum hydrocarbons). John agreed, saying he had only done GoresorbersTM on a quiet street. Nuel asked if they could do a Geoprobe investigation. John replied that he had previous encountered problems here with Hydropunch's groundwater results (ND)not correlating to monitoring well data(10's ofµg/L of PCE).JLB: Was there a possible sampling problem with Hydropunch? Lori and Nuel said that additional monitoring wells may be answer. John said that they would provide a workplan for off-site investigation for SJCEHD and Regional Board review. I asked when? John replied soon,within two weeks. Antecedent:As of this date, the workplan has not been submitted. John wants to discuss a 24 September 2004 report from the drycleaners, which shows hydrocarbons and PCE impacts to soil from dispenser piping and a 250-gallon heating oil UST at a former service station located on the drycleaners property. The piping and UST soil contamination was discovered during construction (expansion) of the drycleaners. Overexcavation removed most of the soil contamination and SJCEHD wants to close the UST site. • The status of current interim remediation actions at the site. John discussed problems associated with excavation of the highly contaminated soil ("hot spot") inside of a 50-year old building. I said that an evaluation by a(licensed) Structural Engineer is necessary before conducting work. John asked if they should we do a limited excavation with risk assessment. I said that a risk assessment is only one tool used for evaluating site closure. Nuel suggested they use modeling to determine if/when concentrations would decrease to acceptable levels in a reasonable time period for site closure. Pat asked if downtown Stockton water was not useable for drinking water due to salt intrusion. I said salt intrusion was not a problem at their site, and that the water may be used as a drinking water source in the future. I also referred to the Santa Clara case where developers tried to include contaminated water as a resource for future development, but the courts said no. So you can't write off downtown Stockton California Environmental Protection Agency W$ Recycled Paper