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r _ <br /> Er��® <br /> James L Barton <br /> ' February 17, 2004 <br /> Page 3 <br /> r MW-23D, and air sparge well AS-26 Well construction details are included in Attachment C <br /> The system layout is show in Figure 13 <br /> Soil Vapor Extraction System Status <br /> Since starting the remedial system, the thermal oxidizer has operated for a total of 6,410 hours, <br /> ' removing approximately 8,462 pounds of petroleum hydrocarbons from impacted soil and <br /> groundwater <br /> ' On September 30 2003, Environmental Audit, Inc of Placentia, CA (EAI) recommended that the <br /> SVE system be shut down In a letter dated October 23, 2003, the RWQCB concurred with <br /> EAI's recommendation to shut down the SVE system and to continue to operate the AS system <br /> in a pulse operational mode <br /> ' A summary of SVE system operational parameters, destruction efficiencies, and mass flow <br /> rates are presented in Tables 4 through 9, respectively <br /> rAir Sparging System Status <br /> The AS system operates in a pulse operations mode (week on 1 week off basis) The sparging <br /> compressor was operated for approximately 578 hours on bi-weekly basis during the Fourth <br /> Quarter 2003 and has operated for approximately 12,690 hours since starting the remediation <br /> ' system <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 TPH as gasoline and benzene vs depth to <br /> ' groundwater are depicted graphically in Attachment F <br /> Concentrations of TPH as gasoline, benzene, and MTBE in groundwater samples collected from <br /> selected wells screened in Unit A or Unit B are depicted graphically on cross section A-A' <br /> r (Attachment E) <br /> Concentrations of TPH as gasoline, benzene, and MTBE in groundwater samples collected from <br /> selected wells screened across Unit A, Unit B and Unit D are depicted graphically on cross- <br /> OU LAlon B-B' (ALt0ch111G11% Lj <br /> ' Fourth Quarter concentrations of MTBE were not reported at or above laboratory reporting limits <br /> in groundwater samples <br /> Soil vapor samples were collected from selected SVE wells and monitoring wells utilized for the <br /> SVE system Samples collected during the Fourth Quarter 2003 were submitted to Air Toxics <br /> LTD in Folsom, California for analyses of VOCs by Modified EPA Method TO-3 Historical <br /> analytical results for soil vapor samples collected from selected wells are summarized on Table <br /> J IProjects1069401293-50981FinalWth Qtr'03-QMR RSR doc <br />' 25 Years of Excellence to Environmental Services <br />