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' Ciealogual Technic I" Page 2 Groundwater Monitoring Report Project No 662 2 April 12,2004 1.0 GROUNDWATER MONITORING 1.1 H dro Bolo of Site y g � The dominant soil type in the upper 40 feet of the subsurface geologic soils investigated is sand, fine to course grained, interbedded with thinner units of plastic clay The average ' groundwater elevation on February 12, 2004 was approximately 13 60 feet above MSL, which is about 25 feet below ground surface This represents an increase of 3 39 feet since the November 21, 2003 monitoring event ' A groundwater gradient was calculated for the event and the groundwater was found to flow N56°E at 0 001 ft/ft Groundwater elevation and gradient data are summarized in Table 1, ' Appendix A Gradient direction is shown on Figure 2 Gradient Map, and Figure 3 Groundwater Gradient Rose Diagram ' 1.2 Groundwater Sampling Procedure On February 12, 2004, Don Light of Del-Tech mobilized to the site to conduct groundwater monitoring of the four monitoring wells on site Before sampling was performed the wells were sounded for depth to water The wells were ' purged of at least three well volumes of stagnant water using a dedicated Waterra check-ball assembly and % inch tubing Purging continued until the temperature, conductivity, and pH of the groundwater stabilized (<10% variation between three readings) indicating that ' formation water representative of aquifer conditions was entering the wells These water quality parameters were measured at intervals of each well volume purged ' Once purging was complete, a water sample was collected from the Waterra tube Care was taken to minimize sample agitation Once the sample container was filled and capped, the ' bottle was inverted, tapped, and checked for headspace bubbles The sample container was identified and labeled with a unique designation, inserted into foam holders and placed in an ice chest cooled to 4°C for transport to the laboratory All non-disposable sampling equipment was decontaminated using a hot water washer and detergent before and between uses Disposable gloves were used by the technician to collect all samples and were changed with each sample collection A chain of custody document, listing all samples collected, accompanied the samples from field to laboratory, thereby providing a means to track their movement and insure their integrity