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;t _~e 3 ,:Jm Herron Fi1I Site Foundational Geohydrology The second paragraph of section 13.2.2, found on page 13-4, states that "the water table was found to be well below the ground surface throughout_ _ the disposal area." Table 13.2.1 (page I3-5), however, indicates that on May 17, 1980 water levels in wells no. 2 and 3 were +0.5 feet and 1.2 feet below ground surface, respectively. The application does rrot contaia sufficient justification to support the applicant's contention, as stated on page 13-7, that "proposed drainage improvements are expected to maintain the water level in this area, at least 5 feet below existing grouad- surface". Section 30 CFR 817.71(1) requires the constriction of a durable rock underdrain system to prevent infiltration of groundwater into the spoil material. The application should be amended to iaclude an approp- riately designed underdrain system within the toe area of the fiZ2 adjoining the highwater areas near test wells 2 and 3. Slope Stability Analysis Slope stability analyses are only significant if they appropriately model the material, mechanical and hydrogeological properties of the refuse . disposal fill proposed. This application states, on page 13-I6, "the long term stability of the pile has been analyzed based on the assumption of 85~ of maximum density and the prescribed factor of safety (30 6FR 817.71) may not be achieved without this density. The stability analysis completed by Espey, Huston and Associates, Snc., employed the SSSAB I slope stability computer program developed by Dx. -= Stephen G. Wright, University of Texas at Austin., This computer program _. - utilizes the spencer method of slices and as such, is a recognized and acceptable method of slope stability analysis. The cross sections analyzed for both phase I of the fill and the complete proposed fill, appear representative and are therefore appropriate. With the appropriate under- drain modifications mentioned above, the potentiometric surfaces assumed in the computer analysis would be acceptable. The material parameters utilized in the stability analysis do not appear to be representative of the refuse fill being proposed_ The application (page 13-8) utilizes material strength parameters determined by "others". The application should contain the reference test results and discussions of their various determination. The application also contains compaction testing results for the existing colluvial soils and representative waste material, depicted in figure 13.3.1. The waste zock maximum density was determined to be 100pcf (pounds per cubic foot) at approximately IS$ moisture content and the colluvial soils maximum density was determined to be 98pcf, at approximately 20~ moisture content. However, the stability analysis (tort' d)