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,Its_ .f <br /> { <br /> UNOCAL <br /> Page 3 <br /> When reviewing the groundwater analytical results for general minerals in Table 5, different <br /> conclusions can be drawn. The level of some miner' is may suggest that water from MW2 and <br /> NP1 is different from the water from MW10 (hardness and zinc), whereas the level of other <br /> minerals may suggest that water from MW10 and N01 is differentfrom the water from MW2 <br /> (magnesium and sodium). <br /> PHS/EHD does not agree that the information provided supports statements that the general <br /> water quality in the vicinity of the site is poor or that the water from NPI represents.salt water front <br /> intrusion and is clearly of different quality than the water from MW2 and MW10. In addition, the <br /> information cannot be used to justify leaving petroleum hydrocarbon contamination in the <br /> groundwater. <br /> Discussions about the biogeochemical data indicating the groundwater plume is undergoing <br /> microbial biodegradation can also be disputed. The[highest dissolved oxygen measurement was <br /> in NP1 where contaminant concentrations are greater than in off site wells. Nitrate and sulfate <br /> levels in the water from MW9 are higher than in the water from MM (both wells are cross <br /> gradient and have only evidenced low levels of contaminants in the water obtained from them). <br /> Quarterly sampling of the monitoring wells must continue. In addition, a work plan to define the <br /> lateral and vertical extent of off site, downgradient soil and groundwater contamination and install <br /> wells on site for feasibility tests should be submitted'by July 1, 1999. <br /> Please be advised that pursuant to Section 25297.15 of the Health and Safety Code, PHS/EHD <br /> has identified UNOCAL as the primary or active responsible party.for this site. It is the <br /> responsibility of the primary or active responsible party to submit a letter to THS/EHD which <br /> identifies all current record owners of fee title and toicertify to PHS/EHD that required notifications <br /> have been made at the time a cleanup or site closure proposal is made orbefore a determination <br /> that no further action is required is made. <br /> If you have any questions contact me at(209)468-3449. <br /> Donna Heran, REHS, Director <br /> Environmental Health Division <br /> Margaret Lagorio, Supervising REHS <br /> Site Mitigation Unit <br /> c: CVRWQCB-Mark List <br /> ARCADES Geraghty & Miller-Dr. Stephen Cullen <br /> SJCADA—David Irey <br /> Helen McCrary <br /> Brooke Birkie, Esq. <br /> Peter Niemiec, Esq. <br />