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Data Interpretation Methods The purpose of the data interpretation is to determine if the Ruby Trust mine setting produces toxic- or acid forming materials that could pose a potential concern to human health or the environment. There are several methods by which the data can be interpreted depending upon the type of data (solids analysis for SPLP vs solids analysis of metals content vs solids analysis for ABA parameters vs water samples for pH measures). For certain types of analysis, there are `regulatory levels' (refer to Tables 5 and 6) which define whether or not the material contains sufficient concentration of a given element at levels considered hazardous/toxic. For other analysis (i.e. ABA and Forms of Sulfur) there are no true regulatory thresholds but rather, interpretive methods or literature-derived thresholds (refer to Table 7) that can be applied to the results. The following describes the interpretation methods for each data set that would assist in the determination of whether the Ruby Trust materials yield toxic- or acid forming- substances. Solids Analysis Methods Chemical characterization of a potentially toxic material is accomplished by two methods; (1) leachability analysis (SPLP) which identifies the potential for constituents of concern to mobilize to groundwater (thereby increasing their threat to human health and the environment), and (2) total material analysis to evaluate the chemical makeup of the material which is intended to identify the constituents of concern. (1) Until recently, the Environmental Protection Agency (EPA) specified characterization of potentially toxic/hazardous materials through the use of the Toxicity Characteristic Leaching Procedure. (TCLP) Recently, however, EPA has been relying on the use of the Synthetic Precipitate Leaching Procedure (SPLP) which mimics more realistic conditions surrounding groundwater leaching. The SPLP method was designed by the mining industry to evaluate the potential for leaching metals into the indigenous and surrounding ground and surface waters. This extraction method provides a more realistic assessment of the metal mobility under actual field conditions and simulates the leaching efforts of acid rain/snow. The leaching fluid is intended to simulate precipitation. The results can be compared to `regulatory levels' to provide an indication (strictly inferential) of which constituents are of concern due to their mobility potential to groundwater. SPLP analysis was conducted for samples of waste rock, ore and tailings collected in 2oo8 and 2oo9. The SPLP results can be compared to Maximum Contaminant Level (MCL) thresholds set forth by the, EPA (refer to regulatory level discussion below) to determine if the material could yield potentially hazardous/toxic levels of certain metals due to leaching. (2) The total material analysis was completed for samples of waste rock, tailings and ore. Samples were collected in 20o8 and 2009 that represent the Ruby Trust materials. These samples were submitted for metals content analysis using standard EPA-approved methods. The results -provide a measure of the metals content in the solid material. 51 Page