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DEC-31-01 13:23 FROM:PATTS COPY WORLD ID= 70793S72SS PAGE 2/7 i2-3062MI C-06"k,k0d—Weil Abanderr� for hI�. 644MT! 2 of 2 Field Procedures The abandonment of groundwater monitoring wells MW-1, MW-2, and MW-3 was performed by a C-57 licensed driller under the supervision of a State Certified 2001 Hydrogeologist(See Figure 1 for Well Locations). According to the November 03, Workplan for Groundwater Monitoring Well Abandonment report,the three(3)wells were to be pressure grouted from the bottom up to the seat, and then, drilled out from the top to the bottom of the seal prior to final grouting.the San Joaquin County Health well abandonment workplan approval letter dated November 07, 2001, required an altemadve method which was to drill out each well to the total depth of the well construction and then grout from the bottom up through the hollow stem auger. The well abandonment was perform according to San Joaquin County requirements. The depth to groundwater was sounded to verify that the water levels were consistent with past readings and that the total depth of each well's casing was measured, in order to verify that no debris or obstructions were present in the well casing. Each of the three wells were over drilled with an a 114 inch diameter hollow-stern auger, through the existing 7 314 inch diameter borehole through the bentonite seal(i.e. between 72 and 75 feet bgs)to 100 feet bgs, during which time,the old well casing and associated well construction materials were removed. The center rod was slipped inside the two(2) inch diameter casing,within the hollow stem of the auger, in order to allow the rod to extract the casing from the borehole during the drilling process. After each well was cleaned out to 100 feet bgs,they were grouted utilizing the hollow stem as a tremie pipe, as per Jeff Wong of San Joaquin County Health,with a Portiand Type 1/11 cement mixed with approximately 56/6 bentonite grout to within 3.0 feet of ground surface in MW-2,within 7.0 feet in MW-3, and to within 5 feet within MW-1. Approximately 20% more grout was used In MW-2, 10% more in MW-3, and 5%more in MW-I,than was anticipated due to grout consumption by the perched gravel aquifer. Each of the three grouted boreholes were later topped off with grout to within 1 '/x feet of the surface and capped with black concrete(See Figure 2 for Cross Section). Approximately 18 drums of drill cuttings and decontamination wager generated during abandonment activities were stored on site in sealed Department-of-Transportation (DOT)-approved, 55-gallon metal drums to be transported to a legal point of disposal. LIMITATIONS This report has been prepared in accordance with generally accepted environmental, geological and engineering practices. No warranty,either expressed or implied, is made as to the professional advice presented herein. The analyses, conclusions and recommendations contained in this report are based upon site conditions as they existed at the time of the investigation and they are subject to change. The conclusions presented in this report are professional opinions based solely upon visual observations made within Individual soil excavations and of the site and vicinity as well as on interpretations of available information as designated in this report.GeoSoly, LLC, maintains that the limited scope of services performed in the execution of this investigation may not be sufficient to satisfy the needs,and/or requirements of all regulatory agencies or other users. Any use or reuse of this document, its findings, its conclusions and/or recommendations presented herein, is done so at the sole risk of the said user. 12-306200= aeoSotv,,UC—WeeReD Abando Report for 111vnan POW 2 of 2