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' Geofogwa[Tec&n s Inc Page 4 <br /> Groundwater Monitoring Report <br /> Project No 4111 <br /> March 24, 1998 <br /> The three domestic wells associated with the site were all non-detect for BTEX MTBE and <br /> TPH-G <br /> 3.0 CONCLUSIONS AND RECOMMENDATIONS <br /> The following conclusions have been drawn regarding the status of the groundwater at this <br /> site and recommendations for future work <br /> Conclusions <br /> 1 Petroleum hydrocarbons are present in five of the nine monitoring wells <br /> 2 The shallow water table groundwater plume is laterally defined except to the west <br /> 3 Free floating gasoline was present in MW-2 in February 1998 <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 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 On a monthly basis monitor the free product in MW-2 to determine if the situation <br /> improves or deteriorates <br /> I 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 /> o 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 San <br /> Joaquin County PHS/EHD, this work should be addressed <br />