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S6p-23-02 04: 36P SIER' PACIFIC GROUP 916 33 3197 P_'04 <br /> Ms. Wendy Wyels <br /> April 23, 1997 <br /> Page 3 <br /> aquifers which have significant recharge capacity, tend to yield relatively mineral-free ground <br /> water. if the good aquifers are not continuously flushed with fresh water, saline ions diffuse into <br /> the fresh water aquifers from adjacent sedimentary formations which still contain saline <br /> constituents. <br /> Sierra-Pacific has described two distinct sedimentary formations (soil types) in numerous soil <br /> borings at the Port of Stockton (Washington Street and Port !toad No. 8 Beed product facilities). <br /> The deeper formation consists of uniform, poorly-graded, olive-green, silt with occasional thin <br /> beds of bluish-gray smectite clay. Water samples taken from the olive-green formation. contain <br /> more dissolved minerals (TDS) than surface waters. The lower sediments are olive-green due to <br /> the presence.of ferrous iron cations. Again, ferrous iron is present in these saturated sediments <br /> due to pervasive anaerobic, or oxygen-deficient, soil conditions. Test results indicate that shallow <br /> ground water at Port of Stockton contains elevated sodium ions, chloride ions, and other TDS <br /> components(Tables 4, 5,and 6). <br /> On the basis of laboratory test data and scientific arguments presented above, Sierra-Pacific recommends <br /> that RWQCB terminate environmental-oversight,and issue a closure letter,for the former Cargill feed <br /> product facility at Port Road No. 8. It may be appropriate to collect a final round of ground water <br /> samples in March 1998 to verify the continuation of the current conditions. <br /> Please call if you have any questions or comments. 'We would be pleased to provide additional literature <br /> references if necessary. <br /> Sincerely, <br /> SIERRA-PACIFIC GROUNDWATER CONSULTANTS, INC. <br /> John Stephen Rapp,CLOT-1133 <br /> Senior Engineering Geologist <br /> .iSWPGD/jb <br /> Enclosures <br /> C. Gary Rimmey;Cargill <br /> Jack Holm,Cargill <br /> Michael lniirrna, San Joaquin County <br /> Charlene Wall, Port of Stockton <br />