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Naidu, Muniappa <br /> From : Manzo, Elena K. <br /> Sent: Monday, July 15, 2019 1 : 11 PM <br /> To: Naidu, Muniappa <br /> Cc: Rivera, Stacy <br /> Subject: FW: Potential New Case SR0078722 <br /> Hi Muni <br /> This is the information that I received from the Water Board ( please see his email below) concerning a work plan for <br /> additional soil excavation at the City of Tracy tank removal site (with lead concentrations at HW levels) . I am not really <br /> sure where we go from here, maybe we can discuss it, unless it was resolved already when I was gone (please let me <br /> know) . I am forwarding it over to make sure you have a copy. <br /> Elena <br /> From: Rader, Geoff@Waterboards <Geoff. Rade r@Waterboards.ca .gov> <br /> Sent: Tuesday, July 2, 2019 1:50 PM <br /> To: Manzo, Elena K. <emanzo@sjgov.org> <br /> Cc: Rivera, Stacy <srivera@sjgov.org> <br /> Subject: RE: Potential New Case SR0078722 <br /> Hi Elena and Stacy, <br /> I met with my boss and another Senior Engineering Geologist in the Storage Tank Program about this case earlier today. <br /> The consensus among the three of us is that a release most likely did not occur at this site . and the elevated lead <br /> concentrations may be naturally occurring. As I mentioned in my last email, the soil sample analytical data does not <br /> seem indicative of a release, and I did not see any notes indicating observations of hydrocarbons stains or odors. If we <br /> were the lead agency on this case, we would not require excavation of this soil . If the City of Tracy was planning <br /> construction at this property, we would require a soil management plan to reduce construction worker ingestion risk. <br /> But if they were just planning to pave the property or leave it vacant, we likely would not require additional work <br /> beyond backfilling the UST cavity. <br /> Regarding the Remedial Action Plan, if you require that City of Tracy to excavate soil due to the elevated lead <br /> concentrations, we would recommend that they conduct additional soil sampling first. Some background soil samples <br /> collected from across the property along with some dee er samples collected with a hand auger within the UST <br /> footprint could give you a better sense of whether these lead concentrations are naturally occurring and, if not, how <br /> extensive an excavation might Be needed to achieve the desired lead cleanup level . A rental XRF unit could also be used <br /> obtain real-time lead concentration data in the field . But the Remedial Action Plan proposes excavation until <br /> confirmation soil samples contain less than 39 mg/kg lead; since this concentration is below literature background <br /> concentration values, this seems far too low to us. <br /> Regarding the soil sample lead concentrations exceeding the STLC Title 22 hazardous waste criteria, my boss said his <br /> understanding is that the hazardous waste criteria dictates how a waste may be disposed, but it does not dictate what <br /> soil must be removed/treated . Our office uses the State Water Board Low-Threat UST Case Closure Policy when <br /> evaluating UST cases for closure, and that policy does not have any requirements for subsurface lead concentrations. <br /> Feel free to call or email if you have any questions. <br /> Thank you, <br /> Geoff <br /> t <br />