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Mr. Verrill Norwood -2- 20 March 1996 <br /> Migration of wastewater from the ponds to the shallow ground water has likely occurred due to the <br /> poor condition of the pond liners and overflows from the ponds. Ground water mounding beneath <br /> these leaking ponds would account for the apparent southwest ground water flow direction. The <br /> regional groundwater flow direction to the northeast probably predominates once outside the <br /> influence of the mounding beneath the ponds. This would explain why VOCs have not been <br /> detected in MW-4 which, based on ground water level measurements on the All Pure facility, <br /> appears to be downgradient of the ponds. MW-4 would be upgradient of All Pure's wastewater <br /> ponds based on the regional ground water flow direction. It is most likely that the VOCs have <br /> migrated offsite of the All Pure facility in the direction of the regional ground water flow to the <br /> northeast. <br /> We agree with your statement that installing two monitoring wells onsite the All Pure facility closer <br /> to the fence line is of questionable value. It would be much more useful to install monitoring wells <br /> offsite of the All Pure facility to the northeast to determine the lateral extent of VOCs in the regional <br /> downgradient flow direction. <br /> The evidence shows that VOCs, including chloroform and carbon tetrachloride, in ground water at <br /> the All Pure facility are a result of leakage and overflows from the wastewater ponds. Therefore, by <br /> 12 April 1996, All Pure is required to submit a work plan to determine the lateral and vertical extent <br /> of ground water contamination. Failure to submit an adequate work plan by that date will result in <br /> our recommendation for a Cleanup and Abatement Order. <br /> We are currently reviewing your plan for closure of the three wastewater ponds and expect to have <br /> our comments to you soon. If you have any questions, you may call Polly Lowry at(916) <br /> 255-3048. <br /> L <br /> 1 <br /> WENDY L. COHEN <br /> Senior Engineer <br /> PAL:pal/lsb <br /> Attachment <br /> cc: San Joaquin County Public Health Services, Stockton <br /> Mr. Tim Vickers, All Pure Chemical Company, Tracy <br />