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' First and Second Quarters 2005 <br /> • CHAPIN BROTHERS INVESTMENTS,INC. <br /> ' 1766 Monte Diablo Avenue,Stockton, California <br /> ' 1.0. INTRODUCTION <br /> At the request of Mr Russell Chapin,Advanced GeoEnvironmental, Inc (AGE) has prepared this <br /> ' report for the site located at 1766 Monte Diablo Avenue, Stockton, California This report <br /> documents the second quarter 2005 ground water monitoring event and procedures for first and <br /> second quarters 2005 operation and monitoring ofthe ground water extraction treatment system The <br /> ' site setting is illustrated in Figure 1 Structures and well locations on or near the site are illustrated <br /> in Figure 2 <br /> Background information and a description of prior investigations at the site are included in the <br /> Appendix A Quarterly monitoring well data from January 1994 to the present is summarized in <br /> ' Tables 1 and 2 in this report <br /> ' 2.0 PROCEDURES <br /> All field work was performed in accordance with Central Valley Regional Water Quality Control <br /> ' Board (CVRWQCB) guidelines for the investigation of underground storage tank (UST) sites <br /> Ground water treatment operation and monitoring were performed in accordance with procedures <br /> described in the approved Remedial Action Work Plan Addendum, dated 28 June 2001 <br /> ' Ground water sampling procedures for monitored natural attenuation (MNA) parameters was <br /> outlined in Ground Water Monitoring- Natural Attenuation Work Plan dated 21 March 2005 and <br /> Ground Water Sampling and Monitoring Natural Attenuation Work Plan Addendum dated 12 April <br /> 2005,approved by the San Joaquin County Environmental Health Department(EHD)by letter dated <br /> 18 Apnl 2005 Groundwater monitoring activities were performed in accordance with guidelines <br /> ' established by the EHD and the CVRWQCB <br /> ' 21 GROUND WATER TREATMENT OPERATION <br /> Between 18 December 2004 and 10 May 2005, a ground water pump-and-treat system was in <br /> ' operation at the site, operating at a maximum discharge flow rate of up to 10 gallons per minute <br /> (GPM) The ground water pump in vapor well VE-6 failed during the start of the first quarter of <br /> ' <br /> .2005 and the ground water recovery rate from the remaining well also decreased due to well fouling <br /> from organic build up and encrustation The ground water pumps in the three remaining extraction <br /> wells operated on an intermitting cycle, extracting ground water for short periods of time (one ^ <br /> ' minute to three minutes), at a flow rate of approximately 5 GPM from well EW-3 and extracting <br /> ground water at a flow rate of approximately 10 GPM from wells EW-I and EW-2 The intermitting <br /> operation of each pump provided a minimum four minute hiatus to allow the water level to recharge <br /> Advanced GeoEnvnronmentai,Inc <br />