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Mr. Nathan Esfoi'mes "or" -3- 'Pe 28 November 1995 <br /> swimming pools and septic systems are significant sources of chloroform in ground water north of <br /> MW-7. The report confirms that ground water north of MW-7 is being used as a source of drinking <br /> water. <br /> Detectable chloroform in ground water north of MW-7 is most likely reflective of the chloroform plume <br /> migrating north from Triple E. However, in lieu of requiring you to install additional monitoring wells <br /> north of MW-7 at this time, you are required to identify all domestic wells between MW-7 and the <br /> Maurland Manor well and develop a monitoring program to determine the exposure to the residents, <br /> approximate extent of contamination, and any trends of chloroform concentrations in ground water. We <br /> will assess the need for additional monitoring wells north of MW-7 after evaluating data from the <br /> domestic wells and the new extraction system. <br /> COST OF EXTRACTING GROUND WATER FROM MW-7 <br /> We concur that there are many logistical and operational problems associated with extracting ground <br /> water from MW-7, as your 9 October 1995 letter states. Although we are not now requiring that MW-7 <br /> be used for extraction, we are still concerned about the extent of chloroform contamination in ground <br /> water north of MW-7 and whether or not extracting ground water from XW-1 will capture the entire <br /> plume. We will defer further evaluation of the ground water extraction system until the system begins <br /> operating and we have the results of domestic well sampling. <br /> ADDENDUM TO REVISED WORK PLAN <br /> The addendum to the revised work plan adequately addresses the concerns in my 19 September 1995 <br /> letter. By 15 December 1995, please provide a schedule to begin operating the extraction system. <br /> To address concerns about the extent of chloroform contamination in ground water north of MW-7, you <br /> are required to submit a work plan by 31 December 1995 which, at a minimum, proposes to identify all <br /> domestic wells between MW-7 and Maurland Manor, determine their depth and screened interval, and <br /> sample a representative number of them on a regular schedule. The work plan shall include a schedule <br /> for completing the well identifications, initiation of monitoring, and regular monitoring. <br /> If you have any questions, you may call me at(916) 255-3048. <br /> f CYPOLLY OWRY <br /> Associate Engineering Geologist <br /> PAL:pal/lsb <br /> cc: San Joaquin County Public Health Services, Stockton <br /> Mr. Robert Dixon, Condor Earth Technologies, Inc., Stockton <br /> Mr. Michael Campos, Graham & James, Sacramento <br />