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i PNA—mi oring Well Destruction Report 500 East Louise Ave.,Lathrop, San Joaquin County, CA March 11,2004 Page 2 pounds per square inch (PSI) of air pressure was applied to the casing to force the grout out into the sand pack. The positive air pressure on each well was maintained for several minutes to ensure maximum displacement of grout within the well casing into the sand pack. An air leak was noted in the grout seal in monitoring well MW.-17 and continuous airflow was applied to maintain positive pressure. After several minutes the air pressure was released and additional out slurry was added to the well casings. P gT QTY g The calculated volume for each of the two monitoring wells and sand packs based on depths of 19 feet was approximately 11 gallons per well. Approximately 9 gallons of grout slurry were emplaced in monitoring well MW-17 despite the air leak in the grout seal, and approximately 15 gallons of grout slurry were emplaced in monitoring well MW-18. Following the pressure grouting procedure, each well was over-drilled down to approximately three feet below ground surface, a minimum 20-inch square was cut in the surface concrete around the well casing of each monitoring well with a concrete saw, the concrete was broken utilizing the drill rigs impact hammer, the broken concrete and the traffic boxes were removed, and the upper three feet around each well was excavated with shovels. The bottom of the excavation was filled with at least one foot of grout slurry and allowed to set. Clean native soil was backfilled into the excavation to within approximately eight inches below the concrete surface and concrete mix was placed over the former traffic box locations to match the existing surface conditions. Refuse from the monitoring well destructions including traffic boxes, concrete, soil, and rinseate water were left onsite for disposal at the discretion of PNA. This report was prepared by Condor under the direct supervision of a Registered Geologist in the State of California. The report was prepared for, and is for the sole use of, PNA. The contents of this report may not be used or relied upon by any other person(s) without the express written consent and authorization of Mr. Roger Bishop of PNA and Condor. Any questions regarding the content of this document should be addressed to Don Kresse at(209) 234-0518. Respectfully submitted, CONDOR EARTH TECHNOLOGIES, INC No.6430 Casey Kipf Donald F.Kresse,R.G. CA Staff Geologist Senior Environmental Geologist Attachments: Vicinity Map (Figure 1) Site Map (Figure 2) SJCEHD Well Destruction.Permit cc: Mr. Roger Bishop,Pilkington North America Mr. Jim Barton(CVRWQCB) P:\3000_pd\3151 Pilkinton PLOF\3151J,UST Review\Reports\WellDestrRpt.doc 1 A _. �1� CONDOR