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1 <br /> Geological TeclucicsW Page 2 <br /> ' Groundwater Monitonng Report <br /> hoject No 662 2 <br /> September 24,2003 <br /> 10 GROUNDWATER MONITORING <br /> ' 11 Hydrogeology of Site <br /> The dominant soil type in the upper 40 feet of subsurface geologic soils investigated is fine <br /> to course grained sand alternating with thinner beds of plastic clay The average <br /> groundwater elevation on August 20, 2003 was approximately 10 53 feet above MSL, <br /> which is about 28 feet below ground surface This represents a decrease of 3 81 feet since <br /> the May 15, 2003 monitoring event This is the lowest recorded groundwater elevation in <br /> the investigation and the water table has fallen almost six feet since the February 2003 <br /> ' monitoring event <br /> A groundwater gradient was calculated for the event and the groundwater was found to flow <br /> East at 0 0043 ft/ft Groundwater elevation and gradient data are summarized in Table 1, <br /> Appendix A Gradient direction is shown on Figure 2 Gradient Map, and Figure 3 <br /> Groundwater Gradient Rose Diagram <br /> ' 12 Groundwater Sampling Procedure <br /> On August 20, 2003, Don Light of Del-Tech mobilized to the site to conduct a groundwater <br /> monitoring of the four monitoring wells on site <br /> Before sampling was perforined the wells were sounded for depth to water and then a clear <br /> disposable bailer was used to detenriine if floating product was present The wells were <br /> purged of at least three well volumes of stagnant water using a dedicated Waterra check-ball <br /> assembly and '/a inch tubing Purging continued until the temperature, conductivity, and pH <br /> of the groundwater stabilized (C10% variation between three readings) indicating that <br /> formation water representative of aquifer conditions was entering the wells These water <br /> quality parameters were measured at intervals of each well volume purged <br /> ' Once purging was complete, a water sample was collected from the Waterra tube Care was <br /> taken to minimize sample agitation Once the sample container was filled and capped, the <br /> bottle was inverted, tapped, and checked for headspace bubbles The sample container was <br /> ' identified and labeled with a unique designation, inserted into foam holders and placed in an <br /> ice chest cooled to 4°C for transport to the laboratory <br /> ' All non-disposable sampling equipment was decontaminated using a hot water washer and <br /> detergent before and between uses Disposable gloves were used by the technician to <br /> collect all samples and were changed with each sample collection <br />