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F a <br /> Startltec <br /> SECOND QUARTER 2009 OPERATIONS MAINTENANCE AND MONITORING REPORT <br /> SHOP 10 MAINTENANCE STATION <br /> Sample Analysis Reporting <br /> July 31, 2009 <br /> .. 3.0 Sample Analysis Reporting <br /> 3.1 LABORATORY ANALYSIS OF GROUNDWATER SAMPLES <br /> +.� Groundwater samples were submitted to APPL, Inc. (APPL), a state of California, DHS-certified analytical <br /> laboratory located in Clovis, California. Groundwater samples were analyzed for total petroleum <br /> hydrocarbons as gasoline (TPHg); total petroleum hydrocarbons as diesel (TPHd); benzene, toluene, <br /> 'r ethylbenzene, and xylenes (BTEX); fuel oxygenates; and lead scavengers. Groundwater analysis was <br /> conducted on a standard turnaround time and in general accordance with method-specific holding times. <br /> Concentrations of 1,2-dichloroethane (1,2-DCA)were reported at levels of 1.5 micrograms per liter(pg/L), <br /> 5.1 pg/L, and 7.4 pg/L in wells MW-13, MW-14A, and VM-2, respectively. No other detections were <br /> reported above the practical quantitation limit(PQL) in any other monitoring wells. <br /> No detections above the PQL were reported in the trip blank or equipment blank samples during this <br /> monitoring event. Cleaning and decontaminating equipment before sampling, use of disposable bailers, <br /> and sampling the wells in order from least to highest impacts reduces the likelihood of cross- <br /> contamination between samples. A summary of laboratory analysis results are provided in Tables 1 and <br /> 2. Second Quarter 2009 groundwater laboratory analytical reports are provided in Appendix A. <br /> 3.2 MONITORED NATURAL ATTENUATION PARAMETERS <br /> (64 Changes in groundwater geochemistry variables can be used to interpret biodegradation activity. In <br /> addition to stripping compounds from water, air sparging can also promote aerobic conditions and <br /> respiration by the introduction of oxygen. During aerobic respiration (oxidizing conditions), oxygen is <br /> 'r consumed, DO concentrations decrease, and CD2 is produced (increasing alkalinity). Carbon dioxide gas <br /> measurements have been collected from system influent and effluent air and from individual SVE wells <br /> since January 2008. Carbon dioxide levels have decreased at monitoring points from an average of 1.73 <br /> percent(readings on January 23, 2008) to 1.2 percent(readings on June 25, 2009). Carbon dioxide <br /> measurements show an overall decrease in carbon dioxide levels in the influent to the system associated <br /> with decreases in hydrocarbon biodegradation on-site. <br /> Natural attenuation parameter DO was measured in the field in all wells during the May 2009 groundwater <br /> sampling event. DO measurements were collected in each well with a down-well probe. Measurements <br /> �. were collected prior to purging to reduce effects of oxygenation associated with purging. Results of <br /> monitored natural attenuation parameters are provided in Table 3. <br /> V <br /> js\1usl329-fOl1secor\project-055-altranslstocklon-shop Mom8m and gw reporling%2DOM2nd qtr 2FX1M1 09 omm_fnl.doc 3-1 <br />