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page 2, 205 Center Street
<br /> SECOR stated in the"Additional Site Assessment Report"t at based on monitoring data collected on
<br /> June 16, 2000 the groundwater flow direction was to the east, In the"Quarterly Groundwater Monitoring
<br /> Report, Second Quarter 2000", which documented data from the same June 16, 2000 event, they stated
<br /> the flow was towards the southeast, and they tabulated it (Table 4, Historical Groundwater Gradient Data)
<br /> as being towards the south. Please have SECOR verify what the actual flow direction was and correct
<br /> their reports accordingly. Also, SECOR tabulated in both submitted reports that the detected
<br /> concentration of MtBE in MW-4, by EPA Method 8260 analy is, was X2.0 parts per billion. This is not
<br /> supported by the analytical laboratory reports from Sequoia nalytical that were submitted to PHSIEHD
<br /> with the"Additional Site Assessment Report". The laboratory report listed the result of this analysis as
<br /> "NW, defined as "not reported", with a specific notation of"N tBE present above calibration range".
<br /> Please have SECOR correct this item in their reports as we . In the Summary of Findings section of the
<br /> "Additional Site Assessment Report"SECOR states that"Fuel oxygenates (TAME, DIPE EtBE, TBA, EDB
<br /> and 1,2-DCA)were reported as nondetect in all soil and gro indwater samples analyzed". While this is
<br /> what the laboratory reported,'the reporting limit that Sequoiz used for the analysis of ether oxygenates,
<br /> 1,2-DCA and EDB in the soil samples was 100 ppb, which i above the standard accepted method
<br /> detection limit of 5 ppb. Moreover, TBA has been detected at this site. At the June 16, 2000 quarterly
<br /> monitoring event, TBA was detected in MW-4 at 225 ppb.
<br /> Reports of findings are due to PHSIEHD within 60 days following the completion of each phase of work at
<br /> a site. In this case, both of the referenced reports were ov rdue. Please have your reports submitted to
<br /> PHSIEHD in a timely manner in the future. Also, all analytical and field data which support statements
<br /> and conclusions made in a report of findings should be included in the report. The laboratory analytical
<br /> report for the analysis of ether oxygenates, dichloroethane, ethylene dibromide and ethanol by EPA
<br /> Method 8260 were not included in the"Quarterly Groundwater Monitoring Report, Second Quarter 2000".
<br /> SECOR suggested that a meeting between ARCO, PHS/E D, the Regional Water Quality Control Board
<br /> (RWQCB), and the Department of Toxic Substances Control be held to determine ultimate site usage and
<br /> regional groundwater cleanup goals at this site. PHSIEHD s willing to participate in such a meeting but is
<br /> of the opinion that the current owner of the property, the City of Stockton Redevelopment Agency should
<br /> be included in the meeting as well. The Redevelopment Agency is the entity most directly involved with
<br /> the current and potential future usage of the site. Further, regional groundwater cleanup goals are
<br /> already available to SECOR. Under the Porter-Cologne Act,waters of the State of California include both
<br /> surface and groundwaters. Water quality goals for waters of the State can be found in "A Compilation of
<br /> Water Quality Goals" (Central Valley RWQCB, August 200 0)and "Fourth Edition of the Water Quality
<br /> Control Plan (Basin Plan)for the Sacramento River and Sa Joaquin River BasinT' (Central Valley
<br /> RWQCB, September 1998). Both of these documents are available on the RWQCB website at
<br /> W-WW.S-wrc-b-.ca.gov/rwqcb5. As stated in the Basin Plan, unl ss otherwise designated by the RWQCB, all
<br /> groundwaters in the Region are considered as suitable or potentially suitable, at a minimum, for municipal
<br /> and domestic water supply, agricultural supply, industrialservice supply, and industrial process supply.
<br /> Therefore, the most protective, appropriate numerical wate quality limit should be selected for a
<br /> particular water body and constituent to protect all applicable beneficial uses of the water. San Joaquin
<br /> County has established that primary and secondary drinking standards, known as maximum contaminant
<br /> levels, are appropriate cleanup goals, at a minimum,for all contaminated underground storage tank sites
<br /> within the county. if you have any questions please call Lori Duncan at (209)468-0337.
<br /> Donna Heran, REHS, Director
<br /> Environmental Health Division
<br /> Lori Duncan, Senior REHS Dot Lofstro RG
<br /> LOP/Site Mitigation Unit IV Engineering Geologist
<br /> cc: Marty Hartzell, CVRWQCB
<br /> Kitty Walker, City of Stockton Redevelopment Agency
<br />€ Bill Brown, Daley& Heft
<br /> Rusty Benkosky, SECOR
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