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Mr. Fernando Amador -4- <br />2 July 1996 <br />which had PNAs and VOCs. The boring log for MW -22R shows specks of lampblack at 3-7 feet, <br />black staining at 20-26 feet, slight diesel odor at 45 feet, and indication of contamination all the way <br />to the water table. In spite of the visual evidence of contamination, PG&E did not take soil samples <br />for laboratory analysis. PG&E should explain why soil samples were not taken. Also, PG&E should <br />explain further why it attributes the contamination to the former service stations when there is clear <br />evidence of contamination by MGP residues. More importantly, PG&E should explain how it will <br />determine the lateral and vertical extent of soil contamination and its potential to contaminate ground <br />water. <br />The report states that the final location of MW -23R may be downgradient of former sources such as <br />the service stations on Church and El Dorado Streets. This statement is true, but MW -23R is much <br />closer to former MGP structures than the former service stations. Therefore, the former MGP <br />structures would impact MW -23R sooner than the former service stations would. Furthermore, as in <br />MW -22R, the boring log for MW -23R shows lampblack at 0.5-4 feet below ground surface. PG&E <br />decided not to install MW -22R due to concerns that the upgradient former service stations could be <br />impacting Area Il. Following this line of reasoning, PG&E should not have installed MW -23R since <br />it showed similar soil contamination and also is downgradient of the former service stations. PG&E <br />should explain the discrepancy in the well installation protocol and why the potential impacts of <br />former service stations on MW -23R is not a concern. <br />Page 20, Zone B Boreholes <br />Instead of referring to the work plan protocol, the report should just succinctly explain why borings <br />MW -22(a) and MW -23 were not suited for conversion to monitoring wells. <br />9. Page 21, Mud -Rotary Drilling <br />The report should describe the fate of the drill cuttings and drilling mud. <br />10. Page 63, Conclusions <br />I have similar comme&,s here regarding contamination in Zone B and the absence of a complete <br />COPC pathway to ground water. <br />If you have any questions, please call me at (916) 255-3049. <br />PHIL, S.ISORENA <br />Associate Engineer <br />PSI:psi <br />