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Geologzcul?echmcs Inc Page 5 <br /> Groundwater Monitormg Report <br /> Project No 425 2 <br /> lie November 17, 1997 <br /> 4 Groundwater gradient historically flows in a northern direction at about 0 002 ft/ft <br /> 5 The site exhibits a downward vertical gradient ranging from 0 0035 to 0 0053 ft/ft <br /> 6 Two domestic water wells, located within about 150 feet down gradient from MW-2, and <br /> one domestic well, located approximately 120 feet cross gradient, continue to be non- <br /> detect for gasoline compounds <br /> 7 The oxygenate suite was tested for by EPA method 8260 MW-1 and MW-5 had <br /> concentrations of MTBE just above detection limits All of the other oxygenates were <br /> non-detect <br /> 8 With several domestic wells associated with the residence surrounding the property and <br /> the wells for the elementary school located a short distance northeast of this property, this <br /> groundwater plume appears to continue to pose a significant threat to public health and <br /> the environment <br /> Recommendations <br /> The following recommendations are made <br /> 1 Begin dipping MW-2 with a clear disposable bailer on a monthly basis to determine if <br /> free product reappears If free product appears begin removing that material by hand <br /> bailing methods <br /> 2 Given the following conditions, GTI feels that further investigation of the vertical extent <br /> • of contamination is warranted <br /> o gasoline has impacted both soil and groundwater to 45 feet below ground surface, <br /> 0 the first drinking water aquifer is only 25 to 30 feet deeper then known <br /> contamination, <br /> o the site exhibits a downward vertical gradient <br /> 3 A work plan was submitted on October 3, 1997 for the installation of three additional <br /> wells to help define the vertical extent of contamination at the site Upon review by the <br /> Mary Meays of San Joaquin County, this work should be addressed <br /> I ' <br /> I <br />