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Mr. Jim Lancaster - 2 - 5 June 2002 <br />Woolsey Oil, Inc. <br />General Comments <br />1. We are concerned that there is no monitoring well downgradient of MW -3. Concentrations of MtBE <br />are consistently on the order of 100 µg/L. The MtBE plume appears to be moving offsite, downgradient <br />from MW -3. We require an additional groundwater investigation downgradient from MW -3, to <br />determine the plume lateral extent and if natural attenuation is occurring. <br />2. The reported method detection limits (MDLs) for VOCs and MtBE are inconsistent with the MRP 5- <br />01-841 requirement of 0.5 µg/L. VOCs and MtBE have been reported as non -detect at 2.0 µg/L. Please <br />work with your laboratory to achieve the MDLs required for all groundwater analyses in the MRP. <br />3. Groundwater from monitoring well MW -9 is not analyzed for MtBE. According to the groundwater <br />contour map, MW -9 is cross -gradient from MW -8, which contains SPP. Since the plume appears to be <br />moving, MtBE groundwater analysis is now required at MW -9, to help assess the lateral extent of the <br />MtBE plume. <br />4. We have revised MRP No. 5-01-841 as recommended to reduce the monitoring frequency at MW -1D <br />to semi-annual. A draft is attached for your review and comment. MRP No. 5-01-841 provides for <br />VOCs to be removed from the program automatically if the VOCs were not detected at the MDL listed <br />in MRP. Note that VOCs use the same analytical method (EPA Method 8260) and chromatographs as <br />oxygenates. Therefore, if VOCs are present in the future oxygenate analysis chromatographs, VOCs <br />reporting is required. <br />In summary, by 1 August 2002: <br />a) Provide a Work Plan. for groundwater investigation to determine the extent of the MtBE <br />plume downgradient of MW -3, and <br />b) Review and provide comments to the revised MRP 2002 -5 -XXX. <br />If you have any questions, you may contact me at (916) 255-3050. <br />AMES L.L. BARTON, R.G. <br />Associate Engineering Geologist <br />cc: Mr. Michael Infurna, San Joaquin County Environmental Health Services, Stockton <br />W. Patrick Riddle, Law Offices of Patrick D. Riddle, Acampo <br />Mr. Gregory Stahl, Ground Zero Analysis, Inc., Escalon <br />