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a sandpack from approximately 15 feet below grade to approximately 34 feet below grade, the depth of completion The interior of the casing was packed with native soil due to sloughing of the excavation sidewalls into the open casing Efforts to remove the blockage were unsuccessful The licensed drilling contractor and RESNA personnel determined that the most practical and effective method to abandon the well was to proceed with backfilling activities, attaining 90% compaction, and subsequently repave the site These actions would effectively prevent any vertical migration of contaminants to the subsurface via the well remnant However, pursuant to on-site direction by PHS/EHD, RESNA placed a temporary conductor casing over the well remnant to provide access at a later date for overdrilling of the remaining portion of the well A 10-inch diameter steel conductor casing was placed over the well remnant using the excavator tractor Backfilling activities proceeded around the emplaced conductor casing On January 4, 1995, Spectrum Exploration Inc attempted to overdrill well remnant MW1 through the conductor casing for the purposes of installing a replacement well The well was overdrilled, but efforts to install a replacement well in the same location were unsuccessful due to unstable and shifting fill material The void created by overdrilling the well was filled with neat cement grout A replacement well (MW1R) was installed immediately east of the excavation pit on January 12, 1995 The location of the replacement well is shown on the site plan, Figure 2 The boring log and well construction details are depicted on Figure 3 GROUNDWATER MONITORING AND SAMPLING A RESNA technician measured the depth to groundwater in monitoring wells MWIR, MW2, MW3, and MW4 on January 17, 1995 using an electronic water level probe Groundwater was present in site wells at 12 34 to 14 39 feet below surface grade Groundwater generally flows to the southeast across the site A potentiometric surface map of the shallow water bearing zone is shown on Figure 4 The apparent groundwater mound around replacement well MW IR can be attributed to residual effects of recharge while the excavation was open to the elements Future trends in groundwater gradient will be monitored closely Groundwater monitoring data are summarized in Table 1 Subsequent to water level measurements, well MWIR was developed by pumping and hand bailing approximately 70 gallons of water Physical parameters (pH, conductivity, temperature) were monitored and allowed to stabilize prior to sampling The well purge log and groundwater monitoring data are included in Attachment 2 Groundwater samples were collected from well MWIR using a disposable bailer The samples were placed immediately on ice and transported to Argon Mobile Labs (DHS Cert #1873) and analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX), TPHg and total petroleum hydrocarbons as diesel (TPHd) using EPA methods 8020/8015 modified TPHg, xylenes, and 1500591SR051095 doc 2