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WARR ASSOCIATES <br /> Mr. Mark Adams <br /> August 8, 2006 <br /> Page 3 of 3 <br /> exits through the uppermost part of a well screen, regardless of the screen length, and stable air- <br /> flow channels are quickly established. The relatively low-permeability layered sediments of the <br /> targeted groundwater zone exhibit a large degree of vertical to horizontal anisotropy (ie., where <br /> horizontal permeability greatly exceeds vertical permeability). Such anisotropy favors the <br /> establishment of relatively thin horizontal air-flow channels, which limit the distribution of <br /> air/ozone in the subsurface. This is why vertically staggered sparging would significantly <br /> enhance the effectiveness and efficiency of the sparging system. <br /> Finally, LPL is concerned about the potential for ozone leakage through the PVC piping <br /> proposed for conveyance. As an alternate to PVC, please consider the use of the flexible type of <br /> conduit commonly used for underground natural-gas conveyance. This type of flexible line is <br /> available in long, continuous rolls, which would speed installation and minimize the number of <br /> conduit joints (heat-welded). Even though the PVC piping proposed for use in the Phase IV IRA <br /> Plan would be pressure tested (at least initially) for leaks, the flexible gas lines are less apt to <br /> develop leaks long after the installation and initial pressure testing are completed, when soil <br /> settlement and/or soil shifting might occur. Also, the above-ground conveyance connection <br /> joints to the ozone generator and the air/ozone compressor should be flexible and designed to <br /> resist earthquake damage. <br /> Thank you for your assistance in addressing LPL's concerns, and we look forward to LCERT's <br /> implementation of the Phase IV IRA. Please feel free to call the undersigned to discuss things at <br /> any time. <br /> Sincerely, <br /> • 7M � <br /> ohn M. Farr, Ph.D., P.E. Anne M. Farr, Ph. . <br /> Chief Engineer Chief Geohydrologist <br /> cc: Phil Johnson, Sims Groupe Management <br /> Marie McCrink, California RWQCB, Central Valley Region <br /> Mike Infurna, San Joaquin County EHD <br /> David Gouker, City of Stockton Public Library, Public Repositories <br /> David Sadoff, AIG Environmental <br /> Donald Bradshaw, LFR QPOFES810 <br /> Lucas Goldstein, LFR yQe'o�N M. Fq9<�y <br /> 9 � <br /> W <br /> No.C322 m <br /> s <br /> Exp.12/31/06 a <br /> r CML �3 <br /> �lP OF CALAFOP <br />