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Creelog"I Technics Im Page 4 Groundwater Monztonng Report Project No 724 2 . April 25,2006 ' pair is double that observed in the other two well pairs, which may have an influence over the vertical gradient direction 1.2 Groundwater Sampling Procedure ' On February 24, 2006, Del-Tech Geotechnical Support personnel arrived on-site, opened the wells and measured the depth to water with an electrically actuated sounding tape The water level reading was recorded to an accuracy of 0 01 foot In wells where free-floating product ' is suspected, a clear disposable bailer is used to gauge the interface No free-floating product was observed during this monitoring event Stagnant water in the well casing was purged using a dedicated Wattera pump as recorded in the field logs (Appendix C) The rate of well purging was monitored The wells were purged of at least three casing volumes until the groundwater parameters (temperature, conductivity, ' and pH) had stabilized (Appendix C) Groundwater parameter stabilization was characterized by three successive readings within 10% variance Wells MW-6, MW-7 & MW-111 went dry before three well volumes were purged ' Before a sample was collected, the water level was allowed to recharge to at least 80% of the initial level All purge water removed from the monitoring well was placed in a properly labeled 55-gallon DOT (Department of Transportation 17-H) approved container and is temporarily stored on-site ' A dedicated Wattera pump was used to collect each sample Water samples were transferred in a manner that minimizes sample aeration during transfer ' of the sample into 40-m1 VOA vials preserved with Hydrochloric acid All samples were checked for headspace bubbles, labeled, inserted into foam holders and placed into an ice ' chest cooled to 4°C for transport to the laboratory The sampling technician, while collecting all samples, wore disposable gloves A chain of ' custody document, listing all samples collected and their intended analyses, accompanied the samples from field to the laboratory, thereby providing a means to track their movement and ensure their integrity 1.3 Laboratory Analyses ' The groundwater samples collected on February 24, 2006, were delivered to Excelchem Environmental Labs of Roseville, California (certification #2119) for analyses of ' • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX) by EPA method 8260B • Total Petroleum Hydrocarbons as Gasoline (TPH-G)by EPA method 8260B • MTBE EPA method 8260B