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Mr. Robert Graulich Page 4 and RJ Lee Group (RJ Lee) . The mean concentration of crystalline silica in the ash was calculated to be 2.29 percent' (by weight) . Crystalline Silica Particles <io microns: Wadham provided results of analyses performed by RJ Lee from eight ash samples analyzed to determine the percentage (by weight) of the ash which had a particle size of <10 microns, and the percentage of the <10 microns fraction which was crystalline silica. The ash was found to contain a mean concentration of 1.37 percent of particles with a particle size <10 microns. Of that fraction, a mean concentration of 0.02 percent was determined to be crystalline silica. The mean concentration of crystalline silica with a particle size less than 10 microns is therefore 0.02 percent of 1.37 percent, or 0.00027 percent (0.0002 x 1.37) . DISCUSSION In the Department's May 2, 1990 evaluation, it was determined that the ash being generated at that time contained an average concentration of 16 percent crystalline silica. An average of 0.036 percent of the ash was measured to be respirable crystalline silica. In its current request, Wadham has demonstrated a significant reduction in crystalline silica content of the ash: the ash has been measured to now contain a mean concentration of approximately 2 percent crystalline silica. Respirable crystalline silica has been measured in the ash at a mean concentration of 0.00027 percent by weight. Although Wadham was able to reduce the crystalline silica content of the ash, two questions remained regarding the assessment of whether this waste poses a hazard to human health and safety and the environment: 1) Will the crystalline silica particles fracture and form smaller, respirable particles?; and 2) Even though crystalline silica is present in the ash (some respirable) , does the ash pose a hazard or risk and therefore warrant regulation as a hazardous waste? These two issues are discussed below. Fragileness of Particles: One of the primary concerns identified by the Department in its previous determination was that the larger crystalline silica particles might, under normal handling conditions, fracture and become respirable. There is no specific test method which has been developed to determine the fragileness of particles (i.e. , the capability of a small particle to 'This value includes both cristobalite and quartz. No tridymite was detected in the ash samples.