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Mr. Ray Von Flue i January 26, 2010 Page 2 of 4 The hazardous waste criteria for chromium found in footnote (d) of California Title 22 CCR66261.24(a)(2) states "If the soluble chromium, as determined by the TCLP set forth in Appendix I of chapter 18 of this division, is less than 5 mg/l, and the soluble chromium, as determined by the procedures set forth in Appendix II of chapter 11, equals or exceeds 560 mg/1 and the waste is not otherwise identified as a RCRA hazardous waste pursuant to section 66261.100, then the waste is a non-RCRA hazardous waste." During the 1991 effort to incorporate the federal regulations into California regulations, some interpreted that the Department of Toxic Substances Control (DTSC) was changing the STLC threshold for chromium III from 560 mg/l to 5 mg/l. In order to remedy this misinterpretation, DTSC added this footnote to explain that in most cases it remains 560 mg/l. The federal hazardous waste level for soluble chromium using the TCLP test is 5 mg/1. California has a WET test threshold for chromium III of 560 mg/l as long as the TCLP test is less than 5 mg/1. Using the same reasoning,the WET test threshold for chromium VI is 5 mg/l. A decision tree showing the logic for determining whether a waste containing chromium III is presented on Figure 1. A decision tree showing the logic for determining whether a waste containing chromium VI is presented on Figure 2. Results of the May 29, 2009 sampling event conducted by the County are inconclusive since the analyses did not seek to determine whether the total chromium was composed of chromium III or the more toxic chromium VI, and whether the bead blast is a RCRA waste as determined by the TCLP test. Independent sampling of the bead blast material was undertaken by Fremouw Environmental Services, Inc. ("Fremouw") on November 30, 2009. Three samples were collected and submitted for laboratory analysis according to protocols established by the U.S. Environmental Protection Agency and were handled under chain of custody control. Fremouw Sample CS-003 was collected randomly from 5 drums of hot and cold shot bead blast into two 4 oz glass jars. Siena Testing Labs used this sample to determine partical size distribution. Results show that 100 percent of the bead blast passes the #10 sieve, thus there is no need to remove non-friable solids that do not pass this sieve and are extraneous and irrelevant as hazardous waste constituents (Title 22 Chapter 11, Appendix II-1). Sample CS-004 was collected randomly from 5 drums of hot and cold shot bead blast into one 4 oz glass jar. Block Environmental Services used this sample to determine aquatic toxicity using the acute 96-hour bioassay using fathead minnows in accordance with California Title 22, Section 66261.24(a)(6). Results show a 95 percent survival rate at 500 mg/l. The hazardous waste criterion for this test is less than 50 percent survival.