ARCHIVED REPORTS_SECOND SEMIANNUAL AND 2011 ANNUAL GROUNDWATER MONITORING REPORT

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2.RESULTS FOR SECOND SEMIANNUAL PERIOD 2011 The wells were gauged and sampled in the order indicated above (from cleanest to most 'i contaminated) to minimize the potential for cross contamination. Figure 2 shows the < locations of the wells, and Table 1 presents a summary of the construction of the wells. Field Methods Field gauging and sampling activities were conducted by Blaine Tech Services, located in J Sacramento,California. Copies of field notes from Blaine Tech are provided in Appendix A. Gauging All wells were gauged prior to any sample collection. Each well that had the potential for the presence of NAPH was screened for its presence using an oil-water interface probe, which included wells M-10,N-7,N-8,N-15, N-16,N-17,0-1,and RW-1. No NAPH was measured. The presence of sheen was checked using a clear Teflon bailer,but no sheen was 1 observed. - 1 Depth to groundwater was measured using an electronic water-level meter or the oil-water interface probe in each well. The measurements were made to the nearest 0.01 foot from a surveyed measuring point at each well location.Groundwater elevations were calculated by subtracting the depth to groundwater from the surveyed elevation at the surface of the .� measuring point. Groundwater Sampling J After gauging,the HydraSleeve samples were collected from the samplers that were set at the midpoint of the water column within the screen intervals after the first quarter 2011 —� sampling event,which was completed on March 2,2011 (wells N-7,N-8,N-15,N-16,N-19, N-24,and RW-1).These samples were collected by lifting the HydraSleeve samplers from the well after they had been in place for approximately 6 months.Physical parameters (temperature, electrical conductivity [EC],pH,dissolved oxygen [DO],oxidation-reduction ' J potential [ORP],and turbidity)were measured from the HydraSleeve samplers. After sample collection using the standard purge method,new HydraSleeve samplers were set at the midpoint of the water column within the screen intervals for each monitoring well for retrieval during the next semiannual 2012 monitoring event. Following HydraSleeve sample collection,each monitoring well was purged using the J "standard method," with a submersible pump or bailing by hand with a clean disposable bailer.Physical parameters (temperature,EC, pH,DO,ORP,and turbidity)were monitored _ to assess stabilization during the purging process for each monitoring well. The field parameters were measured using a flow-cell because DO and ORP are sensitive to J atmospheric conditions and can change once exposed to the atmosphere. — i Each well was purged until a minimum of three well volumes was removed,and .� groundwater samples were collected after water levels had recovered at least 80 percent of the original level.Using a disposable bailer,groundwater samples were collected in laboratory-supplied containers.The samples were labeled,placed in a chilled cooler,and J delivered to Alpha Analytical, Inc.for analysis. Chain-of-custody protocol was maintained throughout the sample-handling process. I Water that came from the wells during purging, sampling,and decontamination activities J was stored temporarily in 55-gallon drums,pending waste characterization and disposal. J 2.2 ES102411163308SCO/LW3521.DOCx1112970003