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3 0 GROUNDWATER MONITORING ACTIVITIES <br />' 31 GROUNDWATER ELEVATION AND HYDRAULIC GRADIENT <br /> On December 2 and 3, 1998, static groundwater elevations were measured in seven <br /> monitoring and/or vapor extraction wells Groundwater depths were measured using a <br /> groundwater interface probe A summary of the depth to groundwater data collected <br /> during this monitoring event and previous monitoring events is presented in Table 1 <br /> Based on the groundwater data, the inferred groundwater flow direction beneath the site is <br /> to the east (Figure 2) with an average hydraulic gradient of 0 0027 meter per meter <br /> (0 0027 foot per foot) <br /> 3 2 GROUNDWATER SAMPLING <br /> Groundwater samples were collected from seven monitoring and/or vapor extraction wells <br /> Prior to the collection of groundwater samples, the monitoring wells were purged of a <br />' minimum of three well volumes of water and until pH, conductivity, and temperature <br /> stabilized The wells were allowed to recover to at least 80 percent of their original static <br /> groundwater levels prior to sampling <br />' The following procedures were implemented for well monitoring, well purging, and water <br /> sampling <br /> 1 All equipment was washed prior to entering the well with an Alconox solution, <br /> followed by two tap water rinses and a deionized water rinse <br /> 2 Prior to purging the wells, depth-to-water was measured using an Solin <br /> st <br /> groundwater interface probe to an accuracy of approximately 0 01 foot The <br />' measurements were made to the top of the well casing on the north side <br /> 3 Monitoring wells at the site were prepared for sampling by purging the well of <br /> approximately three well volumes of water using a Grundfos submersible pump <br />' 4 Water samples were collected with a single-use Teflon bailer after the well had <br /> been purged and water in the well had equilibrated to approximately 80 percent of <br /> the static water level or two hours after well purging, whichever occurred first The <br />' water collected was immediately decanted into laboratory-supplied vials and <br /> bottles The containers were overfilled, capped, labeled, and placed in a chilled <br /> cooler prior to delivery to the laboratory for analysis <br /> 5 Cham-of-custody procedures, including chain-of-custody forms, were used to <br /> document water sample handling and transport from collection to delivery to the <br /> laboratory for analyses <br /> 6 Groundwater samples were delivered to the State-certified hazardous waste <br /> F \TRA-='RR\PRO.IE^'\GLT! , 7f0jIN3,'?l0\0M4i - N DOC <br />