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Mr. James Levy 0 - 2 - • 7 April 2006 <br /> Six stormwater runoff samples from the newly replaced culvert contained 320 to 950 ug/1 of TPH in <br /> unfiltered water samples. UPRR states that the type of TPH is unknown, but submitted chromatograms <br /> show the TPH is primarily the heavier-end fraction. Five of the six samples subjected to lab filtration <br /> and silica gel cleanup were non-detect. One sample contained 200 ug/1 TPHd in the filtered sample. It <br /> is noted that UPRR uses Dustac® to control dust at the railyard. Dustac® is a liquid containing a <br /> lignosulfonate by- product of wood pulp that binds tightly with soil particles. UPRR submitted a <br /> chromatogram of Dustac® that shows several peaks through the TPHd and TPHmo ranges. It is not <br /> clear how much TPH is contributed by Dustac®, if any. However, Regional Board staff concur that the <br /> TPH detected in the stormwater runoff is not from the 2003 TPHd spill but from some other source in <br /> the railyard, probably a non-point source stemming from railyard operations. <br /> The 81h Street Storage Area Soil Investigation Report contains the results of soil sampling and <br /> stormwater outfall sampling from the 8th Street Storage Area. The soil sampling showed minor TPH in <br /> the upper 5 feet of this area, but water samples from the culvert outflows contained up to 10,000 ug/1 of <br /> TPHd and from 560 to 3,400 ug/1 of TPHmo. Staff are concerned that substantial TPH is being <br /> discharged to surface waters. <br /> Regional Board staff concur that UPRR can remove the plug from the recently replaced culvert at outfall <br /> SW-3. However, UPRR needs to investigate the source of the TPH being discharged from the 8th Street <br /> Storage Area, and initiate a monitoring program to determine the frequency and consistency of the TPH <br /> pollution in the surface runoff from the storage area and from SW-3. By 7 June 2006, please submit a <br /> work plan to assess the source of the TPH in the stormwater runoff and propose a monitoring program. <br /> If you have any questions, you may contact me at (916)464-4677 or by email at <br /> djuth a,rb5s.swrcb.ca.gov. <br /> GERALD f. DJUTH, P.E., C.E.G. <br /> Associate Engineering Geologist <br /> cc: Mr. Harlan Knoll, San Joaquin Environmental Health Department, Stockton <br /> Mr. Jack Kemp, Kennedy/Jenks Consultants, Sacramento <br />