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2� Er ' ' 34 Well Development On June 18 and July 29, 2004 SECOR developed the monitoring wells by surging and bailing ' using a surge block and bailer to remove fine-grained sediments from each well and sand pack Periodic measurements of pH, conductivity and temperature were be made during development to establish baseline values for groundwater Approximately 10 well volumes ' were removed from each well during development All water generated during the development activities was stored in DOT approved 55-gallon drums pending disposal Waste disposal is discussed in Section 8 0 ' 3.5 Groundwater Sampling Based on the April 13, 2004 letter from the SJCEHD (Appendix A), requesting that ' groundwater samples be collected and analyzed from all appropriate permeable intervals with the CPT boreholes, SECOR collected grab groundwater samples from two water bearing zones (i a high-permeable soil zone) at each CPT location The grab groundwater ' samples were collected from, three to five foot thick, sand layers present at approximately 60-feet and 80-feet bgs ' Each grab groundwater sample was collected from a separate and adjacent borehole using a modified HydroPuncho sampler Prior to sampling, a water level meter was used to confirm that the drive rods did not contain water The sampler was driven to approximately three feet below the desired sampling depth and retracted three feet to expose the disposable schedule 20 polyvinyl chloride (PVC) screen and allow groundwater to enter the HydroPunch®sampler The water sample was collected by lowering a 3/4"-diameter stainless steel bailer through the drive rods to groundwater The groundwater was bailed from the drive rods, decanted from ' the bailer into 40-m1 VOA vials, and capped Each VOA vial was checked to ensure no bubbles were present, labeled, placed on ice, and transported to the laboratory under chain- of-custody documentation The drive rods were retracted, leaving the disposable drive tip ' and four foot length of PVC well screen in the hole On July 30, 2004, groundwater samples were collected from the monitoring wells Well ' purging and sampling equipment was thoroughly cleaned prior to purging and sampling each well The sampling procedure for each well included measuring the water level and checking for the presence of liquid-phase hydrocarbons (LPH), using either an electronic indicator and ' a clear Teflon" bailer or an oil-water interface probe Each well was purged of approximately three casing volumes of water (or to dryness) using a submersible pump or bailer The equipment and purging methods used for the sampling event are noted on the field data ' sheets included in Appendix B During purging, temperature, pH, and electrical conductivity were monitored After purging, water levels were allowed to recover to 80% of the original levels prior to collection of the water sample Groundwater samples were collected using a disposable Teflon® bailer, placed into appropriate EPA-approved containers, labeled, logged ' onto chain-of-custody documents, and transported on ice to a California state-certified laboratory 1 1 32262 Assessment& Feasibility Report&SCM doc 5 September 30 2004 ' 77EL 32262 04 0502