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1 - <br /> KIM <br /> Mr James L Barton <br /> October 29, 2004 <br /> Page 4 <br />' Air Sparging System Status <br /> The AS system was started in October 1999 as required by CAO No 5-00-707 The AS system <br /> operation was modified to pulse-operations mode (week-oniweek-off basis) in October 2003, <br />' based on RWQCB approval, as stated in their letter dated October 23, 2004 <br /> On September 24, 2004, AS system operations were returned to continuous operation as <br />' required by CAO No 5-00-707 <br /> The AS system has operated for approximately 14,381 hours since in-situ remediation at this <br />' site began in October 1999 <br /> Effectiveness of Remediation System <br />' System effectiveness is evaluated by assessing groundwater data from monitoring wells MW-2, <br /> MW-3, MW-11, and MW-12 Concentrations of TPHg, benzene, and MtBE in groundwater <br /> samples collected from selected wells screened in Unit A or Unit B are depicted graphically on <br /> cross-section A-A' and cross-section C-C' (Attachment E) Concentrations of TPHg, benzene, <br /> and MtBE in groundwater samples collected from selected wells screened in Unit A, Unit B and <br /> Unit D are depicted graphically on cross-section B-B' (Attachment E) Graphs of TPHg <br /> concentrations, benzene concentrations, and groundwater elevation versus time are included in <br /> Attachment F <br />' Soil vapor samples were collected from selected SVE wells and monitoring wells utilized for the <br /> SVE system Samples collected during the third quarter 2004 were submitted to Air Toxics LTD <br /> (Air Toxics) in Folsom, California for analyses of VOCs by Modified EPA Method TO-3 <br /> Historical analytical results for soil vapor samples collected from selected wells are summarized <br />' in Table 10 Tabular results of recent soil vapor sampling analytical results are summarized in <br /> Table 11 Copies of the laboratory analytical results with chain-of-custody documentation are <br /> included in Attachment D. <br /> Installation of Monitoring well MW-9R <br /> On August 16, 2004, ENSR supervised the installation of groundwater monitoring well MW-9R <br /> and the destruction of groundwater monitoring well MW-9 The work was conducted in <br /> accordance with ENSRs Monitonng Well Installation and Well Destruction Work Plan dated <br /> July 30, 2004 The work plan to replace MW-9 with MW-9R was approved by the RWQCB, with <br /> a r_ �„��.,� �,.�.,..%,JA A��n + A �nnd A copy of the RWQCB letter is <br /> conditions, as speciiieU in 1[YY4LL+B 1GLLe ua ed r,uyuoL <br /> included in Attachment G <br /> rPermits <br /> Well construction details and well destruction permits were obtained from San Joaquin County <br /> Environmental Health Department (SJCEHD) Copies of approved permits are included in <br /> Attachment H <br /> N1DcsacramentolprojectsTrDlects1D694015098-293TinaRReportslQuartedy Monitonng ReportsW%3rd Qtr 04-QMR doc <br /> �AlBt7c�1!!7Q�; Vgr'IS Or�X�PIIonEP 7f"tl?Vri'1PfnPn�A JrRf'CP` <br />