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The alternate to flood imgation is the utility of subimgatiom to enhance crop production. The potential for <br />subimgation to occur depends upon depth of rooting of selected species and water table elevation during the growing <br />• season. Data wllected previously by P & M indicate there are restricted areas in which subirrigation does occur. <br />The extent of this, based upon vegetation type, was verified during the 1997 growing season by vegetation production <br />studies within the defined Fish Creek AVF. <br />The area that TCC is proposing to undermine th the Fish Creek drainage is located in parts of sections 10, 11, 15 and <br />16 of TSN, R86W is identical to the azea that P&M Coal Company was planning on undermining and subsiding in <br />its proposed Fish Creek Mine. P&M contracted with the consulting fire of Kaman Tempo to prepare a report <br />responding to the requirements of Rule 2.06.8(4). This report has been incorporated into Exhibit 7e-2. The soils <br />information presented in the Kaman Tempo report was updated with the work performed by Habitat Management, <br />Inc., and a copy of their report is presented in Exhibit 7e~. Additionally, chemical and physical properties of the <br />Brow Silty/Clay Loam are presented in Table 73. None of the data presented indicates a problem with this soil, for <br />example the low SAR's indicate that leaching will not be problematic downstream of the mined area. The original <br />data presented on this table was taken from Table 72 of permit C 81-071. The wnclusions presented in the report <br />agree with TCC's opinion that subsidence of the alluvial valley flwr will not materially damage the existing ranches. <br />It should be noted that the Kaman Tempo report was prepared in ] 982 and since that time the management practices <br />have not changed, i.e. large acreage ranches to meet the ewnomic requirements of the marketplace. This ownership <br />pattern continues in the Twentymile Park basin. The ownership patterns are reflected on Map 1, Surface Ownership. <br />The ownership of pazts of sections IS and 16, TSN, R86W has changed since the P&M study was completed. <br />During the study period Mr. Perley Green owned the property and he subsequently sold it to P&M. P&M in turn <br />sold the property to l..og Creek Inc., who in turn exchanged the parcel for other acreage owned by Twentymile Coal <br />Company (formerly Cyprus Western Coal Company). Presently, Twentymile Coal Company owns the property. <br />• TCC wntracted with SubTerra, Inc. to expand the subsidence predictions to further evaluate impacts to Fish Creek <br />and its alluvial valley floor. This report is presented in Exhibit 7e-3, Northern Mining District, Fish Creek AVF. The <br />report provides a numerical analysis of approximately 2000 cross-sections through the subsided area, and also used a <br />3D Gwlogic Modeling software program (GEMCOM) to wmpaze against the mathematical model. The results of <br />the mathematical model show that of the 560 acres in the alluvial valley floor approximately 70 will be impacted by <br />subsidence. Using the GEMCOM model approximately 84 acres would be impacted by subsidence. It should be <br />noted that the 16 acres identified wlumns 3 and 6 of Table 7 in the SubTerra Report presented in Exhibit 7-e3 <br />presents the surface azea of Fish Creek prior to subsidence (16 acres) and this area is subtracted out of the total AVF <br />flooded area presented in wlumns 2 and 4 in the table. <br />Tn reference to a change th the gradient of Fish Creek, SubTerra analyzed the creek from stations 200 to 2020. The <br />analysis included evaluating the gradient both before and after mining. The result of this analysis is presented on <br />Table 4 in the report (sae Exhibit 7e-3). Also, the narrative includes a discussion of change in gradient of the creek. <br />Mining of the 12 Right panel will result in no impact to the AVF during the low flow period. As mining wntinues to <br />the north and wal is removed from panels 13 Right through 16 Right the cumulative number of acres to be flooded <br />during the low flow period is 70 acres using the mathematical model and 84 acres using the GEMCOM model. Panel <br />I3 Right will involve flooding 26(mathematical model) or 39 (GEMCOM model) acres, panel 14 Right will involve <br />flooding l5(mathematical model) or 24 (GEMCOM model) acres, panel 15 Right will involve flooding 19 <br />(mathematical model) or 13 (GEMCOM model) acres and panel 16 Right will involve flooding l0 (mathematical <br />model) or 8 (GEMCOM model) acres. <br />)n reference to TCC's agricultural operations (Trout Creek Ranch), approximately 15,000 acres azea utilized ta the <br />ranching operation. The ranch does utilize flood-irrigated bottomland for hay production. The hay crop is typically <br />• sold to other ranchers for feed. None of these areas will be impacted by the proposed mining operation. <br />PR 99-05 2.06-25.1 ~P'~ ~ u ~ ~ ~ JUN 2 8 2000 g/27/99 <br />