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d� <br /> 3 0 SAMPLE ANALYSIS REPORTING <br /> 31 Laboratory Analysis of Groundwater Samples <br /> Groundwater sample analysis was completed by Advanced Technology Laboratory (ATL), a <br /> State of California, DHS-certified analytical laboratory located In Signal Hill, California <br /> Groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPH/g), <br /> total petroleum hydrocarbons as diesel (TPH/d), benzene, toluene, ethylbenzene and <br /> xylenes (BTEX), fuel oxygenates, and lead scavengers Groundwater analyses were <br /> conducted on a regular 10-day turnaround time and In general accordance with method- <br /> specific holding times A summary of laboratory analysis results are provided in Tables 1 <br /> and 2 Third quarter laboratory analytical reports are provided as Appendix A <br /> 3.2 Monitored Natural Attenuation Parameters <br /> Natural attenuation parameters including DO, ferrous Iron, and ORP were measured in the <br /> field during the September/October (third quarter) 2005 sampling event Natural <br /> attenuation parameters, nitrate, and sulfate are analyzed annually during the second <br /> quarter of each year and were not analyzed during this event Analysis results of monitored <br /> natural attenuation parameters are provided in Table 3 <br /> Biodegradation causes changes In groundwater geochemistry that can be measured as <br /> indicators of biodegradation activity During aerobic respiration, oxygen Is consumed, DO <br /> concentrations decrease, and CO2 is produced, which In turn can increase alkalinity <br /> In anaerobic systems, sulfate (electron acceptor) is reduced to hydrogen sulfide and <br /> nitrates are reduced to nitrogen (denitrification) During denitrification, ferric Iron reduction <br /> and sulfate reduction, CO2 can be produced and total alkalinity can increase Organic <br /> compounds (including CO2) can also be broken down by methanogenic bacteria producing <br /> methane Changes in DO, nitrate, ferrous Iron, sulfate, and methane concentrations are <br /> used to ascertain dominant processes present If reducing conditions are present, methane <br /> analysis will be added to the list of natural attenuation parameters analyzed annually <br /> i <br /> a <br /> { <br /> 11CALTRANS1Stockton-Shop 101GW Monttonngl3rd Qtr 2005103'05 DM&M_FEnal doc November 29,2005 a <br /> Project No 940T 43148 00 SECOR International Incorporated <br />