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Geological Technics!nc Page 2 Groundwater Monitoring Report Project No 662 2 May 5,2003 1.0 GROUNDWATER MONITORING ' 1.1 Hydrogeology of Site The dominant soil type in the upper 40 feet of subsurface geologic soils investigated is fine ' to course grained sand alternating with thinner beds of plastic clay The average groundwater elevation on February 13, 2003 was approximately 16 33 feet above MSL, 1 which is about 23 feet below ground surface This represents an increase of 1 83 feet since the December 13, 2002 monitoring event ' A groundwater gradient was calculated for the event and the groundwater was found to flow N57°E at 0 0013 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 13, 2003, Don Light of Del-Tech mobilized to the site to conduct a groundwater monitoring of the four monitoring wells on site Before sampling performed the wells were sounded for depth to water and then a clear P g was p p disposable bailer was used to determine if floating product was present The wells were purged of at least three well volumes of stagnant water using a dedicated Waterra check-ball assembly and '/2 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