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qeologlca I recl�iics Inco <br /> 1101 7`"street <br /> Modesto,California 95354 <br /> ' (209)522-4119/Fax(209)522-4227 <br /> REPORT <br /> Groundwater Monitoring <br /> 3rd Quarter 2005 <br /> ' J.M. Equipment Company <br /> 1245 West Charter Way <br /> 1 Stockton, California <br /> Project No 507 2 <br /> ' October 31, 2005 <br /> EXECUTIVE SUMMARY <br /> ' This report summarizes the results of the 3`d Quarter 2005 groundwater monitoring and <br /> sampling event that took place on August 19, 2005 The average groundwater elevation at <br /> the site was —10 51 feet mean sea level (msl) and the groundwater flow was N4$°E at 0 003 <br /> 1 ft/ft for this event A vertical groundwater gradient calculation for wells MW-9 & 109 shows <br /> that groundwater is flowing downward at a slope of 0 0045 ft/ft <br /> ' The analytical results of groundwater samples show that detectable concentrations of gasoline <br /> range hydrocarbons were present in five of the site's groundwater monitoring wells for this <br /> event The magnitude of the contamination in the wells is consistent with historical site data <br /> The fuel oxygenate compound MTBE was detected in three monitoring wells <br /> Moderate to strongly negative Oxidation-Reduction Potential (ORP) measurements show that <br />' nine monitoring wells are within the halo of reaction depleted water caused by <br /> biodegradation of the contamination plume <br /> GTI submitted our June 10, 2003 "In-Situ Remediation Pilot Test" work plan for an in-situ <br /> hydrogen peroxide injection pilot test The SJC EHD issued approval of the work plan in <br /> their September 10, 2003 letter The injection process began on March 19, 2004 and a report <br /> on the pilot test was submitted to SJC EHD for review in November 2004 They have since <br /> commented on the field work and requested that a site conceptual model (SCM) be submitted <br /> prior to proposing further corrective action <br /> 1 <br />