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Mr. Joe Aldridge - 2 - 16 December 2010 <br /> NuStar Terminals Stockton Facility <br /> located within and immediately downgradient of historical petroleum hydrocarbon release source <br /> areas at the Site. <br /> Table 6 consists of a partial list of monitored natural attenuation (MNA) parameters observed in <br /> B/C zone wells during May and August 2010. The table does not include monitoring results for <br /> ACA-3D and ACA-5D since these did not exist at the time that quarterly sampling was performed. <br /> Historical MNA results are tabulated in Appendix G. Central Valley Water Board staff requested <br /> that NuStar initiate MNA monitoring to support recommendations presented in its 5 January 2006 <br /> Cleanup Plan. MNA monitoring commenced in April 2007 and initially was scheduled to last for <br /> about one year. However, NuStar extended the monitoring program to include the collection of <br /> geochemical parameters from newly installed wells. <br /> The 12 November 2010 Monitoring Well Installation Report (Report) summarizes the August 2010 <br /> installation of two groundwater monitoring wells (ACA-3D and ACA-5D) to 70 and 92 feet bgs, <br /> r esnectively. No soil or groundwater samples were collected while the boreholes were drilled. <br /> ACA-3D and ACA-51D were sampled on 30 September 2010. ACA-3D, which is closer to the Site's <br /> source area, contained the highest concentrations of TPI-Ig and TPHd at 140 pg/L each. ACA-5D <br /> contained TPHd 52 pg/L. The water quality objectives (WQOs) for TPI-Ig and TPHd are 5 pg/L and <br /> 100 pg/L, respectively, although the cleanup goal for TPI-Ig defaults to the reporting limit of <br /> 50 pg/L. The two wells also contained minor concentrations of BTEX. The wells were installed to <br /> delineate the vertical extent of contaminants in groundwater, as requested by Central Valley Water <br /> Board staff. We concur with NuStar's recommendation to incorporate these wells into the quarterly <br /> monitoring program. <br /> Our comment is provided below. <br /> The significantly elevated reporting limits for TPHd in ST/MW-1 and for TPI-Ig in that well and three <br /> others violate the MRP, which requires TPI-Ig and TPHd to be analyzed at maximum reporting <br /> limits of 50 pg/L. There is a footnote No. 16 on the TPHg result for the four wells with elevated <br /> reporting limits, but the footnote list at the end of the table does not include a No. 16. In the future, <br /> NuStar must adhere to the reporting limits in the MRP and provide explanations for any deviations. <br /> If you have any questions regarding this letter, you may contact me at (916) 464-4811 or <br /> betaylor(aD_waterboards.ca.gov. <br /> BRIAN TAYLOR, P.G. <br /> Engineering Geologist <br /> cc: Ms. Adrienne Ellsaesser, San Joaquin County Environmental Health Dept., Stockton <br /> Ms. Jeffery Wingfield, Port of Stockton, Stockton <br /> Mr. Paul Supple, Atlantic Richfield Company, San Ramon, CA <br /> Ms. Amanda Spencer, Ash Creek Associates, Inc., Portland, OR <br /> Mr. James E. Eisert, Arcadis, Roseville <br /> Mr. Rusty Benkosky, Stantec Consulting Corporation, Rancho Cordova <br />