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r] Austin Road Landfill Is 19 April 17, 1996 462. Could VOCs from the landfill be present in more than one underground aquifer? What explanation does the City give for the VOCs found in the residential wells east of Austin Road?" Yes, VOCs have been found in the lower aquifer at Austin Road as recently as October 1995. Xylene and PCE were found in deep monitoring well MW -6. The City's position is that there plume has not reached the east side of Austin Road. "3. - Can a water sample from MW -14 showing nondetectable constituents of concern be valid evidence the VOC's from the landfill did not cause contamination in the State's agricultural well? Per Clark Well, Inc., the State's agricultural well is 270 feet deep. Are the monitoring wells the same depth?" A single sample of water from MW -14 is not sufficient to convince us that the plume of VOCs in groundwater does not extend beyond well MW -14. During drilling of MW -14, water was encountered at a depth of 77 feet. The monitoring well was completed to a depth of 106 feet, or 29 feet below the water table. Since the agricultural well is substantially deeper than this, it is possible that the plume has bypassed well No. 14. "4. Could the RWQCB require that the City re -test the State's agricultural well and provide a copy of the analysis to OREDS? Since the State's water sample (taken from the well in 1994 through a chain of custody) tested for VOCs and the City questioned the methodology used to conduct the analysis of this sample, it seems only appropriate the City re -test the well. Ya new sampling show no VOCs in the State's well, would this be sufficient evidence from the RWQCB to conclude the contamination from the landfill has not reached SSL 357-3?" We did ask the City of Stockton to test the State's agricultural well, however the City declined due to the oil in the well. As an alternative, the City proposed to install well MW -14, which is between the State's agricultural well and the known plume area. We accepted the City's proposal and the City incurred the expense of installing and sampling an additional monitoring well. With your concurrence we will sample the State's agricultural well to look for pollutants. Our field staff will contact you in the near future to arrange access to sample the CYA wells. If you have any questions, please call me at (916) 255-3140. WILLIAM J. MARSHALL, Chief Waste Discharge to Land Unit NMI cc: Stephen Chen, City of Stockton Department of Public Works, Stockton iS, an Joaquin County Public Health Services, Stockton