SU0004323 SSNL - Laserfiche WebLink

Home Browse Search

KLEINFELDER i The CVRWQCB expressed concerns that detection limits for hexavalent chromium ranged from 50 to 500 parts per billion (ppb) in comparison to the water quality goal of 21 ppb. In addition, the CVRWQCB requested that a sample of storm water to be collected from the site and analyzed for TPH-diesel and hexavalent chromium. 4 RESPONSE ACTION The parent material (concrete tile) and six shallow soil samples were re-evaluated by the analytical laboratory (Sequoia Analytical) in regards to method detection limits (MDLs) which are lower than the reporting limit and closer to the water quality goal for hexavalent chromium of 21 ppb. The MDL for the six soil samples and parent material rinseate ranged from 25 to 250 ppb. These MDL values represent estimated limits for hexavalent chromium concentrations for the soil and parent material samples submitted for analysis. A MDL of 25 ppb was reached in the sample of the parent material (Ll-PM) and 25 ppb in one soil sample location (Ll-0"). No �. hexavalent chromium was detected in either of those samples. Hexavalent chromium was also not detected in any of the other samples collected from the site with MDLs of 250 ppb. According to the analytical laboratory, detection limits lower than 25 ppb could not be reached 6. due to matrix interference. Please note, soil reporting limits are typically higher than water reporting limits and as such, soil sampling reporting limits are not usually at or below water quality goals for a representative contaminant. Partly for this reason, soil reporting limits are not typically compared to water quality goals. On April 4, 2005 Kleinfelder collected a grab water sample directly from puddled water located approximately in the center of the site (Plate 1). The puddle resulted from a rain fall event that occurred on April 3, 2005. The sample was labeled, stored in a cooler with ice, and transported by courier to California Laboratory Services (CLS) of Rancho Cordova, California. No hexavalent chromium or diesel was detected by the laboratory in the stormwater sample collected from the subject site. A reporting limit of 1 ppb was reached during the analysis for hexavalent chromium. This addendum letter is subject to the limitations presented at the end of this letter. Any other party (other than KSN or regulatory agencies having enforcement jurisdiction for the site) who would like to use this document shall notify Kleinfelder, Inc. of such intended use in writing. CONCLUSIONS AND RECOMMENDATIONS No hexavalent chromium was detected by the laboratory re-evaluation of the two samples in which the MDL was 25 ppb. Included in these two samples was the parent material rinseate, the most likely source for constituents of concern (Chromium VI and TPH-D) to impact soil and groundwater at the site. Based on the parent material (concrete tile) sampling results, it appears that the parent material does not contain hexavalent chromium at concentrations near the water ` quality goal of 21 ppb. 52495.EO1/ST05R540/FB:Iv Page 3 of 5 0 2005 Kleinfelder,Inc. May 27,2005