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• 2. EXCESS SPOIL FILLS <br />A. STREETER FILL <br />Requirement <br />Prior to 1994 Colowyo had been required to conduct on the Streeter Fill subsidence monument <br />surveys, piezometer well testing, certified inspections and reports on a quarterly basis. Technical <br />Revision No. 26 submitted to the Division and approved on Mazch 18, 1994, reduced these <br />monitoring requirements. The current monitoring requirements require quarterly piezometer well <br />testing and a spring and seep assessment. Monument surveys, certified inspections and reports are <br />to be completed only during the second calendar quarter. <br />Results <br />Refer to the 1998 Annual Re on rt MaQ for details regazding the specific location of each survey <br />monument and piezometer well location. A summary of survey data and associated diagrams, <br />inspection reports and other information is provided in Exhibit 6. Streeter Excess Spoil Fill. <br />I. Survey Monuments -Fill Settlement -Two monuments aze located at approximately 100' <br />intervals from the 6700' level to the 7200' level for a total of twelve monuments. The survey data <br />suggests that the anticipated settling of the Fill material remains stable with little change. After <br />• initial settling during the first four or five years, analysis of the ongoing monitoring data typically <br />indicates no significant changes. Overall settlement ranges from 1.5 to 4.48 feet (6800 N. Point). <br />2. Survey Monuments -Lateral Movement -Similar to settling, lateral movement remains <br />stabilized. Lateral movement has stabilized at generally less than two feet overall and, with the <br />exception of the 6700' level, in an easterly direction. The 6700' level has settled in a westerly <br />direction. <br />3. No springs or seeps have been noted associated with the Fill. <br />4. Piezometer Well -The 1997 Annual Reclamation report provides a summary of the failure <br />of the Streeter fill North well (the deep piezometer well) in 1997 due to a casing perforation at 114.3 <br />feet (measured from top of casing). The plan for 1998 was to continue to monitor the two wells <br />located on the 6900 bench of the Fill then, based upon the results, determine what the course of <br />action would be. <br />As predicted, the water level in the shallow well (TD at 135.2 feet) continued to drop until it became <br />dry. Curiously, the deep well (TD at 260 feet) located just 15 feet away continued to show an inflow <br />of water from the casing perforation located at the 114 foot level. The sound of the inflow appeazed <br />to decrease, suggesting that the inflow had reduced a little, but never completely subsiding as had <br />been expected. No other definitive flow data is available. To date a plausible explanation why the <br />• <br />