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of groundwater flow direction and hydraulic gradient. Each well was constructed with 2-inch diameter PVC casing, with MW8, MW9, MW10, and MWI I extending to a depth of 65 feet bgs in the shallow groundwater bearing zone, MW5, MW6, and MW12 extending to a depth of 90 feet bgs in the intermediate groundwater bearing zone, and MW7 extending to a depth of 121 feet bgs in the deep groundwater bearing zone. The screened interval of each shallow zone well was ' 20 feet in length. A sand pack was placed in the annulus of each well extending from the bottom of the well screens to at least two feet above each well screen. The screen interval of the intermediate zone and deep zone wells were five feet in length. The screen slot size is 0.020- inch and the wells were surge blocked to ensure an adequate sand pack was in place. Well construction details are depicted on the well logs contained in Appendix A. The locations of the monitoring wells are shown on Figure 2. 2_4 Monitoring Well Development and Surveying Groundwater monitoring wells MW5, MW6, MW8, MW9, MW10, and MW12 were developed on December 22 and 23, 2004 by pumping at least five well volumes of groundwater from each ' well. Purged groundwater was temporarily stored on site in 55-gallon drums prior to disposal by Excell Excavating. An obstruction encountered in MW7 at approximately 64 to 65 feet bgs prevented development of this well. MWl 1 was purged dry after removing 0.5 gallons of water. Efforts to develop this well using a bailer revealed the presence of grout inside the well and the total depth of the well was measured to be approximately 58 feet. Development logs for MW5, MW6, MW7, MWS, MW9, MW10, MW 11, and MW12 are included in Appendix B. 1 On December 22 and 23, 2004 monitoring wells MWI through MW12 were surveyed relative to NAD 83 and NGVD29 for position and elevation. The survey data are presented in Table 1. The ' surveyor's report is included in Appendix C. 2_5 Groundwater Sampling and Analyses On December 22, 2004, fluid levels in MWI through MW12 were measured utilizing an electronic water probe capable of measuring with an accuracy of 11100 of a foot. Groundwater elevation data are presented in Table 2. On December 22 and 23, 2004, ATC personnel collected groundwater samples from MWI through MW6, MWS, MW9, MW10, and MW12. Prior to collection of groundwater samples, the depth to water, pH, electrical conductivity, and ' temperature were measured in groundwater purged from the monitoring wells and recorded. Turbidity was visually observed and recorded. A minimum of three well casing volumes were purged from each monitoring well prior to sampling. The wells were allowed to recover and samples were collected from each well using disposable polyethylene bailers. After samples were collected, dissolved oxygen (DO) concentrations were measured in the purged groundwater. Groundwater samples were placed in a cooler chilled with ice and delivered under chain-of custody documentation to Argon Laboratories for chemical analyses. Groundwater samples were saEnviromenta11283491reports\sum.doc 3 ATC Associates Inc,