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-59- combination of a 28,500 cubic yard topsoil pile and 45,000 cubic yards non-toxic soil cover stockpile outside the footprint of the permanent waste structure. In addition, an access road will be constructed in Phase Three and a portion of the Sylvester Gulch access road to the main fan portal will require relocation. Underdrains will be constructed beneath the pile. Piezometric ground water monitoring will be conducted. The permit revision application included a thorough slope stability analysis performed in accordance with the prudent state-of-the-art of slope analysis. Material strength values were derived from on-site sample testing and nearby previously reported test results. Piezometer observations, falling head parameter tests and analytical projections were conq~leted in order to predict appropriate phreatic surfaces within the proposed waste structure. The minimum deep surface static slope safety factor determined for the pile was 1.57, corresponding to a pseudostatic safety factor of 1.14. The minimum shallow failure surface static slope safety factor was determined to be 1.56, which corresponded with a pseudostatic safety factor of 1.17. The applicant has committed to the installation and monitoring of three sets of survey monuments to monitor slope stability of the waste structure. One row of monuments will be installed parallel to the state highway adjoining the toe of the waste pile on 100 foot intervals. Two additional rows of monuments will be installed perpendicular to the highway on the facial slope of the pile at 50 foot interval spacing. The operator has also committed to monthly performance of visual inspections of the topsoil and non-toxic soil cover stockpiles. For the Lower Permanent Waste Pile, drainage will be controlled by a series of drainage ditches, terraces, and a sedimentation pond. Since the pile will be constructed in phases, the drainage system will also be built in phases. All disturbed area drainage from the topsoil piles, subsoil stockpile and waste pile will be routed to the sedimentation basin at the northwest corner of the lower waste pile. The design incorporates several permanent drainage features into the plan. After final reclamation of the pile, the terraces will be barricaded with rocks or berms to prevent access to the pile. However, the terraces will still function to control runoff from the pile. A permanent diversion ditch will be constructed around the perimeter of the pile to permanently collect any runoff from the site and safely route it to the natural drainage system. For a discussion of the hydrologic effects of the pile both surface and ground water see the hydrology section of this document. Due to the length of time needed to complete laboratory chemical tests of the waste material, WECC was delayed in submitting all the hydrology data on the pile. As a result, a water monitoring plan was not developed prior to the revision decision date. Therefore, the Division must impose the following stipulation: