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4" <br /> Report—Site Closure <br /> New Jerusalem School <br /> July 22,1999 <br /> with much greater quantities of fresh water from other screened intervals. The possibility for detectable <br /> impact of the domestic well is extremely remote to impossible. <br /> 6.2 IRRIGATION WELL <br /> Little is known of the irrigation well other than that samples for TPH-G, BTEX, MTBE indicate no <br /> hydrocarbon fuels are present. No well records are available. In the case of this well, it is still <br /> �.• considered very unlikely that the minor groundwater contamination found at the UST site could have a <br /> measurable impact on the irrigation well water quality. Reasons for this opinion include the apparent <br /> slow transport velocity in the near-surface aquifer, predominance of clay in the contamination zone, <br /> small estimated total mass of contaminant in soil and groundwater (0.25 kg), likelihood that <br /> biodegradation and plume attenuation will diminish the plume concentration, and the fact that any <br /> contaminated water from the upper aquifer pulled into this well would be blended with much more <br /> abundant clean water from other screened intervals. <br /> 7. MONITOR WELL CLOSURE <br /> �.. Closure of monitor wells will be conducted by Spectrum Exploration of Stockton, California(C57 <br /> License 4512268)under supervision of a Condor registered geologist. A PHS/EHD well closure permit <br /> application is included with this work plan. The PHS/EHD will be notified at least 48 hours in advance <br /> of the fieldwork. <br /> Condor will supervise the closure of three monitor wells. The wells will be filled under pressure with a <br /> cement/bentonite(3-5%) slurry. A pressure-grouting device, provided by Spectrum,will be temporarily <br /> installed at the top of each well to pump grout into the wells. In addition,the traffic boxes and associated <br /> surface grout will be removed. Following pressure grouting,the upper 1 to 1.5 feet of all the well <br /> casings will be removed with a cutting tool. The upper portion of the wells will be topped off with neat <br /> cement and brought to grade. <br /> Grout volume calculations are included in Table 5 of this Report. The calculations are based on the <br /> diameter of the borehole and the PVC casing,the height of the PVC casing and filter pack, and an <br /> estimated filter pack porosity of 0.25. The boring logs for the three monitor wells are included in <br /> Appendix B. <br /> v <br /> A letter report will be prepared and submitted to the PHS/EHD documenting the well closures. The <br /> report will discuss the actual amount of grout used and the other stuff. <br /> V <br /> If you have any questions or need any additional information,please call us at(209)234-0518. <br /> Respectfully submitted, i'EREo <br /> CONDOR EARTH TECHNOLOGIES, INC. r rU <br /> R. David Mea e John H. Kramer <br /> Project Manager Registered Geologist CA# <br /> Certified Hydrogeologist CA#182 <br /> 11PDC\PR0JECTS\2500 New Jerusalem\Well ClosureTinal Report.doc <br /> V <br /> V �� CONDOR <br />