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S <br /> r1 t <br /> KLEIRIFELDER <br /> August 8, 1988 <br /> File 24-1132-20 <br /> �U8 � 1988 <br /> Mr David Carls NTAL HEALTH <br /> San Joaquin Local Health District E�IVIR�ME SEFtV1CtS <br /> P O Box 2009 VERMI-U <br /> Stockton, CA 95201 <br /> RE: Response to Comments Made on the Jordan Real Estate Proposal <br /> Dear Dave <br /> In response to the comments you made during our August 3, 1988, telephone conversation <br /> regarding the Jordan Real Estate Proposal, I am submitting this letter which addresses your <br /> concerns <br /> 1 EDB Sampling - Since earlier sampling detected no EDBs and EDBs are <br /> listed as an optional parameter for soil sampling in the June 2, 1988, <br /> document "Regional Board Staff Recommendations for Initial Evaluation <br /> and Investigation of Underground Tanks,"we do not feel that comprehensive <br /> EDB sampling is necessary In response to your request that we test for <br /> EDBs,we propose to test the water samples from the two downgradient wells <br /> for EDBs <br /> 2 High Moisture Content - Appendix A, Kleinfelder Field Procedures, is a <br /> general description of field procedures used by Kleinfelder staff Since this is <br /> a general description, not all of the techniques listed will necessarily be used <br /> in every investigation Using high moisture content as a criteria for selecting <br /> soil samples will not be employed at the Jordan site. This technique is useful <br /> in situations where there is liquid migration from a landfill or surface <br /> impoundment <br /> 3 Well Development and Sampling - You were concerned that we proposed to <br /> pull samples from the wells 24 to 48 hours after development You <br /> mentioned that Gary Johnson at the Regional Water Quality Control Board <br /> recommended that two weeks elapse between well development and <br /> sampling Monitoring wells are developed to remove any material that may <br /> hinder the free flow of ground water into the well lumen During <br /> development, pressure waves are used to dislodge the blocking material <br /> These pressure waves may affect the concentration of volatile organics and, <br /> therefore, the volume of water affected by these waves cannot be used for <br /> sampling <br /> In his book "Ground Water and Wells," F G Driscoll states that filter packs <br /> for wells should be no thicker than 8 inches because the strong pressure <br /> waves generated during development do not travel much further than 8 <br /> inches If we conservatively assume that the ground water within a 1 foot <br /> radius of the well is affected by the pressure waves and cannot be used for <br /> sampling, we can look at how that volume of water can be avoided <br /> KLEINFELDER 9795 Business Park Drive, Suite C, Sacramento, CA 95827 (916) 366-1701 <br />