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f6. Geofogica!?edmks fru. Page 3 Soil Groundwater Investigation Report Moresco Project No. 251.3 c.. June 7, 1999 • benzene, toluene, ethylbenzene and xylene (BTEX by EPA method 8260B), • gasoline range petroleum hydrocarbons (TPH-Gasoline by EPA method 826013) • oxygenated fuel compounds (MTBE, DIPE, ETBE, TAME, TBA) by EPA method LN 8260B The detection limits for these compounds are listed below. A Chain of Custody was completed for all samples collected and tracked to ensure sample integrity. Detection imus: Soil (Vg/Kg) k. 2.2 Monitoring Well Installation To investigate the possible presence of gasoline in the groundwater at this site, Geological Technics Inc. installed one groundwater monitoring well through the former UST location (Figure 2, Site Map). The monitoring well was constructed using 4.0-inch diameter PVC casing with flush threads. The screened interval on MW-1 extends from the water table to fifteen feet below the water table (95-110 feet bgs). Groundwater was encountered at approximately 95 feet below grade. A #12 sand filter pack surrounds and extends two feet above the 0.010" screened interval and was topped by a three foot bentonite chip transition seal installed on top of the filter pack. A ,y surface seal was achieved by pumping a neat cement grout (augmented with <4% bentonite) via a tremie tube. The well was secured with a locking watertight cap encased in a flush mounted traffic rated well box. 60 On April 5, 1999 Don Light of Del Tech mobilized to the site to developed the new monitoring well (using mechanical surging and pumping methods) until a clear stream of water was obtained. On April 8, 1999, Don Light returned to the site to purge and collect a LN groundwater sample from the monitoring well. On May 19, 1999, Don Light returned to the site to purge and collect a second set of groundwater samples from the monitoring well. All development and purge water was containerized in 55-gallon DOT approved containers and stored on site until its disposition can be arranged. 2.2.1 Groundwater Sampling Procedure The groundwater in the new well was sampled no sooner than 24 hours after well t.0 development. The following was the procedure for the sampling of groundwater from the well: L. Before sampling was attempted the well was sounded for depth to water. The wells were then purged of at least 3 well volumes of stagnant water using a submersible pump. Purging continued until the temperature, conductivity, and pH of the groundwater has stabilized (<10% variation between three readings) indicating that formation water representative of aquifer conditions was entering the well. These water quality parameters were measured at intervals of each well volume purged. A stainless steel bailer was used to collect each sample. Care was taken to minimize sample agitation from the initial filling of the bailer to the transfer of the sample to the VOA vials. V I.r