ARCHIVED REPORTS_SITE CHARACTERIZATION REPORT 1999

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7kadweIERdlo 3.1.5 New Monitoring Well Development All newly installed monitoring wells were developed using a surge block and purging the groundwater with a submersible pump. Physical water quality parameters of the discharge water ' were periodically measured, as were observations such as color,turbidity, and sediment content. Equipment used for the development of the wells was cleaned with a trisodium phosphate ' solution and rinsed with clean water. Approximately ten well casing volumes of water were removed from each well during the well development. ' 3.1.6 Groundwater Sampling Methodology P g Prior to groundwater sampling at existing wells, groundwater levels were taken from the top of the casing. The wells were then purged of approximately five well casing volumes using a ' submersible pump. Physical water quality parameters, including temperature, pH, and electrical conductivity, were measured, and observations such as color,turbidity, and sediment content were noted after the removal of each well casing volume. After purging, groundwater samples from each well were obtained for chemical testing using a new disposable bailer at each well. At each temporary boring location where grab groundwater samples were collected, tubing was ' lowered into the boring through the drilling casing and groundwater was extracted with a peristaltic pump. All groundwater samples were decanted into laboratory-prepared containers ' and immediately sealed, labeled, and placed in an ice-cooled chest until delivery to the laboratory using chain-of-custody procedures. 3.2 Area 2A 3.2.1 Geophysical Survey On 18 August 1999,NORCAL conducted a geophysical survey at Area 2A. The investigation area is shown in Figures 1 and 2 of the NORCAL report in Appendix B. The geophysical survey was performed using the VMG and TC methods. NORCAL measured points across the area in 8 25970119.DGD 13 December 1999