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2. EXCESS SPOIL FILLS <br />• A. STREETER FILL <br />Requirement <br />Prior to 1994 Colowyo had been required to conduct subsidence monument surveys, piezometer well <br />testing, certified inspections and reports on a quarterly basis. Technical Revision No. 26 submitted to <br />the Division and approved on March 18, 1994, reduced these monitoring requirements. The current <br />monitoring requirements require quarterly piezometer well testing and a spring and seep assessment. <br />Monument surveys, certified inspections and reports will be completed only during the second calendaz <br />quarter. <br />Results <br />Two monuments aze located at approximate 100' intervals from the 6700' level to the 7200' level on the <br />Fill for a total of twelve monuments. Refer to the 1996 Annual Report Map for details regarding the <br />specific location of each monument. A summary of the survey data and associated diagrams are <br />provided in Exhibit 6. Streeter Excess Spoi[ Fiil. This survey monument data indicates that the trends <br />of the past years aze continuing: <br />• 1. The anticipated settling of the fill material remains stabile and unchanged. After initial settling <br />during the first four or five years, analysis of the ongoing monitoring data indicates no <br />significant changes. Overall settlement ranges from 1.5 to 4.1 feet (7000 N. Point) which is <br />minimal considering the depth of the fill at the upper elevations (over 250 feet). <br />During 1995 the 6700' level survey monument data indicated that the elevation of the entve <br />bench had risen almost .5 feet over the previous yeaz. After further investigation we found that <br />the north reference point located on the sandstone rock bluff had actually settled because of <br />movement of the bluff itself. Because of this reference point settling the 1995, 6700' level data <br />was in error. On May 31, 1996 Colowyo submitted a report to the Division summarizing the <br />work to evaluate the 6700' reference point and reestablishment of a new point to monitor the <br />three lower benches of the Fill using XYZ coordinates. Exhibit 6 contains a copy of the report <br />in addition to the survey data and diagrams showing the initiation of the new methodology. <br />• <br />