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TREADWELL & ROLLO 4.3 Groundwater Elevation Measurements On 23 August 1991, the north rim of the top of each well casing (TOC) was surveyed by R.W. Siegfried & Associates, a licensed land surveyor. A site-specific datum was established based on a bench mark along the northern property line (Figure 2). On 28 August 1991 and 17 September 1991, the depth to groundwater below the top of the casing was measured using a tape. The results of the survey and the water levels are presented in Table 1. 4.4 Well Development and Sampling Sufficient time elapsed to permit curing of the well grout packs to cure prior to well development on 23 August 1991. All wells were developed by using a surge block and evacuating groundwater by bailing with a stainless steel bailer until the well water cleared. All equipment was steam cleaned before use and between wells. A total of 50 to 105 gallons of water (30 to 70 well casing volumes) was removed from each of the wells during development. 4.5 Water Quality Sampling The wells were sampled on 23 August 1991 and resampled on 17 September 1991: The depth to water in each well was measured prior to sampling. The results of these measurements are presented on Table 1. The wells were sampled immediately subsequent to development on 23 August 1991. These wells were resampled on 17 September 1991; a minimum of four to five well volumes were removed from each of the wells prior to sampling. A stainless steel bailer was used to purge and develop the wells. Well purging continued until the pH, specific conductance, and temperature of the water stabilized. These measurements were performed at regular intervals during well purging and are the criteria for determining when "fresh" representative formation water has entered the well. 5 1107A201.CRJ 5 November 1991