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• Mr. Sam Brenneke, Shell Oil Products US - 3 - 6 July 2012 <br /> Shell Stockton Terminal <br /> reach WQOs. A few examples of the discrepancies between Shell's estimates <br /> and the observed concentration data are shown below: <br /> MW-3: The trend analysis states the trend is stable; however, the greatest <br /> total petroleum hydrocarbon as gasoline (TPHg) concentration ever <br /> detected (260 micrograms per liter (pg/L) was observed in <br /> September 2011. <br /> MW-8: The trend analysis states benzene will reach the WQO of 46 pg/L <br /> by January 2010; however, the second highest concentration (73 pg/L) <br /> was observed in September 2011. <br /> MW-11: The trend analysis states benzene reached the WQO of 46 pg/L <br /> in September 2009; however, the August 2010 concentration was <br /> 320 pg/L. <br /> MW-13R: The last seven detections are above the trend line (i.e., the <br /> concentration is underestimated by the trend analysis for the last seven <br /> monitoring events); therefore, the trend line is not a good fit for the data <br /> and should be adjusted. <br /> MW-18: The trend graph states the TPHg concentrations reached the <br /> WQO of 210 pg/L by March 2003; however, the September 2011 was <br /> 520 pg/L. <br /> MW-24: Eleven of the last 12 concentrations are above the trend line; <br /> therefore, the line is not a good fit for the data, the future concentrations <br /> are underestimated, and the trend line should be adjusted. <br /> 3. The Central Valley Water Board staff 19 April 2012 letter notified Shell that the <br /> WQOs presented in the FS/CAP are too high and are not correct. The <br /> 15 September 1998 Water Quality Control Plan for the Sacramento and San <br /> Joaquin River Basins (Basin Plan) provides the following WQOs 100 pg/L for <br /> TPHd and 5 pg/L for TPH-g. Since the normal detection limit for TPH is 50 pg/L, <br /> the default WQO for TPH-g is 50 pg/L. Shell needs to prepare future trend <br /> graphs using the correct WQOS. <br /> 4. The FS/CAP states that the saltwater intrusion into groundwater at the Site <br /> means it is highly unlikely that groundwater could be used for drinking water. <br /> Shell requests the Site be considered an exception to the MUN designation in the <br /> Basin Plan. Changes to the Basin Plan require a Basin Plan amendment and <br /> Shell should discuss this process with the Port of Stockton. <br /> 5. Central Valley Water Board staff concurs with the recommendation to implement <br /> MNA at the Site. Shell needs to continue to conduct groundwater monitoring in <br />