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glance, it would appear that Seneca II-W overburden is more acidic. Ninety-two percent of . the acidic portions of the Seneca 11 overburden are between a pH range of 6.0 and 7.0; whereas, only 77 percent of the acidic portions of the Seneca II-W overburden are between the 6.0 to 7,0 pH range. Some or all of this difference could be attributed to the fact that almost twice as many cores were analyzed at Seneca II-W and only two of the Seneca II cores penetrated the Lennox coal. Seven of the Seneca II-W cores included the Lennox coal and all of the acidic portions < pH 6 were associated with the Lennox and the immediately overlying and underlying shales. The percentage of all cores with material < pH 6 is minimal and the ABP accounting indicates that the associated overburden material exhibits a very high neutralization potential. Resultant spoil water at Seneca II-YI is not expected to have a pH of less than 7.0. The mean pH value for the spoil aquifer at Seneca II is 7.5 and individual samples have never shown a pH below 7.1. A comparison of the physical characteristics (particle sizes) permits hydrologic inferences to be drawn. The percent sand, silt, and clay fraction of each core at Seneca II-W and Seneca II was determined. The values for each core are presented in Table 17-7. The sand percentage in Seneca II-W cores is ten percent lower than at Seneca II. Thus, the corresponding silt and clay percentages in the Seneca II-W overburden are higher. • This provides a general indication of the parent material differences between the two mines. Seneca II-W likely has a higher percentage of shale in the overburden material than does Seneca II. As was the case with the comparison of paste pH's, a greater number of cores were analyzed at Seneca II-W and only two of the Seneca II cores penetrated the Lennox coal and its associated shale layers. The apparent particle size differences may not be as much as the core data suggest. Based on the particle size data available, Seneca II-W spoil is expected to have lower infiltration rates and horizontal hydraulic conductivities than Seneca II spoil. The cation exchange potential in the overburden aquifer and spoil at Seneca II-W should be greater because of the higher percentage of clays present. Thirty-one chemical parameters were evaluated in cores at Seneca II and II-Vl. Tables 17-8 and 17-9 present a summary of the mean weighted concentrations of each measured parameter in each of the cares and the mean weighted concentrations of parameters when considering the total length of all cores at each mine. A comparison of the major cations and anions analyzed in cores at each mine indicate that there is twice as much sodium present in the overburden at Seneca II and approximately twice as much calcium, magnesium, and sulfate • present in the overburden at Seneca II-W. In evaluating the sulfur species, there is 1.7 22