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16 <br /> 5.0 GROUNDWATER GRADIENT AND FLOW DIRECTION <br /> Groundwater depths were measured in each well, prior to purging and sampling on <br /> December 18, 1999 Depths were measured relative to the north side of the top of each well <br />' casing The monitoring well top-of-casing (TOC) elevations were surveyed relative to an <br /> arbitrary benchmark (chiseled square set at southeast corner of residence, assumed elevation of <br /> 100 00 feet) on February 19, 1999 by Quartarob &Associates In each well, groundwater depth <br /> was subtracted from the respective well casing elevation to establish a groundwater elevation <br /> Cumulative groundwater elevation and gradient data is summarized in Table 3 <br />' On the basis of the December 1999 groundwater measurements, groundwater flows to the <br /> southeast with a surface gradient of 0 04 Figure 3 presents a Generalized Potentiometnc Surface <br /> 1 Map for the December 1999 groundwater monitoring event <br /> 6.0 GROUNDWATER MONITORING WELL SAMPLING <br /> BSK performed well sampling activities on December 18, 1999 Prior to purging of the wells for <br /> sampling, water from each well was observed for floating product Floating product was not <br /> observed in the four morutoring wells The monitoring wells were purged of at least four well- <br /> casing volumes The temperature, conductivity, and pH were measured and recorded after each <br /> approximate well volume <br /> After to purging, each monitoring well was allowed to recover, then water samples were <br /> collected from each well using a clean disposable bailer The samples were labeled, placed in an <br /> ice chest cooled with crushed ice, and submitted to a State-certified analytical laboratory for <br /> chemical analysis of TPHg and BTEX by EPA Method 8015/8020 (Modified), and fuel <br /> oxygenates and 1,2-DCA by EPA Method 8260 Equipment used during purging and sampling <br /> activities was cleaned with non-phosphate detergent wash and rinsed prior to use at each well <br /> location The purged groundwater was stored in appropriately labeled 55-gallon drums at the <br /> Site. Water Sampling Logs are included m Appendix A <br /> 7.0 ANALYTICAL RESULTS <br />' A summary of analytical results for the fourth quarter of 1999 are presented in the following <br /> Table A A cumulative summary of quarterly monitoring analytical results is presented in Table <br /> 2 Laboratory Data Reports and Charas-of-Custody documentation are included in Appendix B <br /> Statue Report-0740017B-Fourth Quarter 1999 3 <br />