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' 06 July 1999 AGE-NC Project No. 95-0197 Page 3 of 8 2.1.3. Logging Duringdrilling activities, sam le duplicates were monitored for the presence of organic vapor using g P P an organic vapor meter equipped with a photo-ionization detector (PID: Thermo Environmental ' 580A, 10.0 eV, calibrated to isobutylene)and were visually described on boring logs in accordance with the Unified Soil Classification System (USCS). Boring logs are included as Appendix A. General lithology beneath the site in cross sectional view is depicted on Figures 3 and 4. 2.1.4. Monitoring Well Completion Soil borings MW-1 through MW-4 were single-completed as ground water monitoring wells ' utilizing schedule 40, 2-inch diameter blank polyvinylchloride (PVC) well casing and perforated, 2-inch diameter PVC well casing (0.020-inch slot). Each well was installed by placing a PVC well casing assembly through the hollow stem of the augers to the total depth of the boring. The augers were incrementally raised as No. 3 Lonestar Lapis Luster sand (filter pack)was slowly poured down the annulus between the well casing and the inner lie wall of the hollow stem auger. The filter pack was placed adjacent to the screened casing from the bottom'of the boring to a point approximately two feet above the top of the screen; following filter pack placement, a surge block was inserted into the well casing and was alternately raised and lowered(surged)repeatedly for approximately 10 minutes.Two feet of bentonite chips(annular seal) were placed above the filter pack and were hydrated with clean tap water. The remaining annular ' space was backfilled with portland cement (grout seal). As-built monitoring well-construction diagrams are included as Figures 5 through S. ' 2.1.5. Surveying of Monitoring Wells ' On 14 June 1999, a California state-licensed survey engineer from Baumbach & Piazza, Inc. surveyed a reference point on the top of wells MW-i through MW-4 to the nearest 0.01-,foot relative to the City of Stockton Bench Mark Datum BM# 364. The results of the monitoring well survey are ' contained in Table 2. The surveying report (Baumbach & Piazza Job No. 9797) is presented in Appendix B. 2.1.6. Well Development Activities ' On 12 April 1999, monitoring wells MW-1 through MW-4 were developed utilizing a Teflon hand bailer and a two-stage submersible pump. 1 Advanced GeoEnrironmental,Inc.