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RULE 4 PERFORMANCE STANDARDS <br />4) Colowyo completed an annual inspection of the Streeter Fill each year of this time period <br />during the second calendar quarter by a registered engineer. This inspection included a <br />specific examination of items 1 and 2 above and included a discussion of the facial conditions <br />of the fill in order to determine whether the development of perched water tables within the <br />fill was affecting its surficial slope stability. <br />5) The monitoring reports and certified inspection reports are available during inspections by the <br />Division but were only submitted to the Division in the Annual Reclamation Reports. <br />On 9/9/97 monitoring of the 6900 well indicated that the steel casing had failed at the 114.3' level <br />allowing water from a pre-existing perched water zone to enter the well at that level. Subsequent <br />monitoring for the next year indicated that the inflow was variable but never completely subsiding. As <br />such, the W690ON well could no longer be relied upon to monitor for development of a perched water <br />zone in the base of the fill. In September, 1998 Colowyo proposed Minor Revision MR -48 to install a <br />new monitoring well on the 6700 bench of the Streeter fill. The W6700 well could serve as the new <br />piezometer well for monitoring purposes (see item #2 in the preceding section). The installation of the <br />well was completed on October 13, 1998 and the as built information submitted through the MR -49 <br />process. Refer to Drawing 30A — Revised Streeter Fill As Built for a location of the Streeter fill wells. <br />Information obtained from the two 6900 wells (drilled in the early eighties) could be of some interest in <br />the future so the two wells will remain in place for possible future monitoring. No formal monitoring <br />program is proposed at this time for the two 6900 wells. <br />Streeter Fill Monitoring (2006 forward) <br />In 2006, Technical Revision No. 64 was approved to discontinue all monitoring and reporting <br />requirements for Streeter Fill. This change corresponds to the requirements of Rule 4.09.1 and 4.09.2 <br />because all construction has been completed. <br />West Pit and Section 16 Pit Excess Saoil Fills <br />To develop the West Pit and Section 16 Pit, it was be necessary to construct two excess spoil fills from <br />material in the initial cuts. The designs details for these fills is presented in Exhibit 19 — Geotechnical <br />Investigations, West Pit Fill and Section 16 Fill. <br />The volumetric balance indicating excess spoil will be generated and disposal of excess spoil will be <br />required is found in Section 2.05.3. <br />In 2006, Technical Revision No. 64 was approved to discontinue all monitoring and reporting <br />requirements for the Section 16 Fill. <br />In 2017, all monitoring and reporting for the West Pit Fill was discontinued in accordance with Rules <br />4.09.1 and 4.09.2, as construction of the West Pit Fill has been completed. The West Pit Fill monitoring <br />well will continued to be monitored until Phase I1 bond release is achieved on the West Pit Fill <br />constructed limits. <br />4.10 Coal Processing Waste Banks <br />No coal processing waste banks are planned for the Colowyo mining operations. Therefore, this section <br />is not applicable to this application. <br />Rule 4 Performance Standards 4-31 Revision Date: 1/31/18 <br />Revision No.: TR -119 <br />