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Mr. Nathan Crum -2- <br />Valley <br />2 - <br />Valley Pacific Petroleum Services, Inc. <br />28 November 2007 <br />We concur with the suggested approach to preparation of the FS as well as the proposed <br />locations of the two monitoring wells. The rationale for equipping the monitoring wells with 20 - <br />foot screens, however, is unclear. Screening an interval of this length may complicate <br />identification of strata bearing dissolved product by imparting a dilution effect on groundwater <br />samples obtained when the groundwater table is elevated during the wet season. Additionally, <br />non -aqueous phase liquid (NAPL) historically has not been observed in the areas proposed for <br />monitoring well installation. Therefore, screening across the upper capillary zone at 45 feet <br />bgs to gage NAPL thickness will not be a design consideration for the proposed wells. The <br />Regional Water Board suggests limiting the screened interval to the 10 vertical feet between <br />55 and 65 feet bgs. <br />By 25 January 2007 please submit the Well Installation and FS reports. If you have any <br />questions regarding this letter, you may contact me at (9-16) 464-4811 or <br />betaylor@waterboards.ca.gov. <br />BRIAN T , G. <br />Engineering Ge V ogist <br />cc: Mr. Gregory Stahl, Ground Zero Analysis, Inc., Escalon <br />Mr. Patrick Riddle, Law Offices of Patrick D. Riddle, Acampo <br />Mr. John Miller, Valley Pacific Petroleum Services, Inc., Stockton <br />Mr. Harlin Knoll, San Joaquin County Environmental Health Department, Stockton <br />