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1 _ <br /> 1 <br /> E11f��t® <br /> • Ms Margaret Lagorio <br /> 1 December 22, 2004 <br /> Page 3 <br /> 1 SP-213, SP-2C, and SP-313) Sparge points SP-1A, SP-2A and SP-3A were not operated during <br /> the fourth quarter 2004 since the sparge points were not submerged in groundwater Ozone <br /> sparge points introduce ozone into the areas of highest dissolved VOC concentrations near the <br /> 1 eastern property boundary of the Unocal site Each sparge point has a dedicated line and is <br /> connected to the system by LDPE tubing The LDPE tubing runs through Schedule 40 PVC <br /> conveyance piping for added protection <br /> 1 Ozone Microsparae System Operation <br /> The timer schedule is set to cycle through each operational sparge point 18 times per day, for <br /> nine minutes per point per cycle There is an eight-minute rest period between cycles The <br /> programmable timer/controller is varied during the quarter to provide more treatment to selected <br /> areas <br /> Ozone Microsparge System Status <br /> System operation began on August 14, 2002 System effectiveness is assessed by measuring <br /> periodic concentrations of dissolved oxygen (D O ) and monthly analysis of groundwater from <br /> monitoring wells MW-2, MW-10, and MW-11 and piezometer well NP-1 Wells MW-2, MW-10, <br /> I� MWA1, and NP-1 are located adjacent to the eastern property boundary of the site (Figure 2) <br /> and are within the zone of influence of one or more sparge points Well MW-2 is screened from <br /> 20 to 50 feet below ground surface (bgs) Wells MW-10 and MW-11 are screened from 50 to <br /> 60 feet bgs Well NP-1 is screened from 85 to 90 feet bgs A summary of D O concentration <br /> I data is presented in Table 3 Concentrations of TPHg and benzene versus time and TPHg versus <br /> depth to water in wells MW-2, MW-10, MW-11, and NP-1 are depicted graphically in <br /> Attachment D A system layout diagram is included as Figure 7 and the well completion details <br /> are included in Attachment E <br /> Effectiveness of Ozone Microsparae System <br /> Quarterly groundwater samples were submitted for analyses of BTEX by EPA Method 8021, <br /> TPHg by EPA Method 8015 Modified, and fuel oxygenate compounds MtBE, TAME, TBA, DIPE, <br /> and ETBE using EPA Method 82608 Additionally, groundwater samples were analyzed for lead <br /> scavengers EDB, and 1,2-DCA, using EPA Method 8260B <br /> Periodic groundwater samples are collected from wells MW-2, MW-10, MW-11 and NP-1 to <br /> further assess the effectiveness of the system The samples are submitted for analysis of BTEX <br /> by EPA Method 8021 and TPHg by EPA Method 8015M The results from these events are <br /> reported with a summary of analytical results included in Attachment D as Table D-1 <br /> Discussion <br /> IAnalytical results from wells MW-2, and MW-10 through MW-12 indicate that the ozone <br /> • microsparge system appears to be effective as evidenced by the overall decreasing petroleum <br /> hydrocarbon concentrations Increases were observed in petroleum hydrocarbon concentrations <br />' llbrsacramentolprojects4Projects106940U859-3571PinahReportsQ859 4th Qtr 04-QMR RSR doc <br />' o Celebrating 35 Years of Excellence in Environmental Services <br />