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FIRST HALF 1998 SUBSIDENCE SURVEY REPORT I. Survey Data During the first half of 1998, subsidence survey data was collected periodically from established monuments on the Hayden -Gore Pass Power Line, and the Wolcott Tap - Wolcott Power Line in those areas underlain by gate roads or panel centers during periods of active ingwall mining. The 7 Right Longwall Panel did not directly undermine the powerlines, and this is reflected in the data. Prisms were set on legs of the metal structures of the Hayden-Gore Pass power poles at HS8A, H58B, H58C, H58D, H59A, H59B,H59C, and H59D. The prisms were surveyed initially on May 27, 1998 and surveying continued until July 26, 1998. Daily surveys were conducted from May 28, 1998 through June 19, 1998. Weekly surveys were conducted from June 25, 1998 through July 26, 1998. The survey data is presented on the attached disk, under the file name pwrpanel7.xls, and the sheet name of Hayden-Gore. The Wolcott Tap -Wolcott survey data for the first half of 1998 are summarized in Table 2. Prisms were set on power poles at P86A, P86B, P87A and P87B and initially surveyed on May 27, 1998. Daily surveys were conducted from May 28, 1998 through June 19, 1998. Weekly surveys were conducted from June 26, 1998 through July 26, 1998. Foidel Creek was surveyed after the 7 Right Longwall Panel subsidence and the profile provided in the First Half 1997 Subsidence Report, see figure 1. Foidel Creek will be surveyed again in the Fall of 1998 to develop a profile of the creek showing the subsidence effects due to the mining of the 6 Right Longwall Panel. This profile will be included in the Second Half 1998 Subsidence Report. II. Structures Structures affected during the first half 1998 reporting period include the Union Pacific Railroad track, the Hayden -Gore Pass power line, the Wolcott Tap -Wolcott power line, and the Western Area Power Administration power line, and Foidel Creek. The Union Pacific (UP) Railroad track visual inspections were conducted by UP maintenance personnel from July 1, 1998 through July 13, 1998 for the first of 1998. The maintenance work performed during the period of subsidence included placement of additional ballast on an as needed basis, and releveling the track with a production tamper. All of the maintenance work was performed by UP personnel. The section of track requiring maintenance work was located over the gateroads, thus the limited extent and amount of work necessary for this piece of track over the 7 Right tailgate. The Hayden -Gore Pass line, Wolcott Tap -Wolcott line and Western Area Power Administration line daily visual inspections were conducted concurrent with the survey of