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No irrigation headgates are located over or in close proximity to the panels. The AVF evaluation for this area <br />documented that flood irrigation of the bottom lands is not practical, and that any enhancement of vegetative <br />growth in these areas results from natural sub - irrigation. Subsidence of portions of the valley floor will increase <br />the potential for sub - irrigation to occur, since seasonal flooding, ponding, and localized lowering of the ground <br />surface will result in higher ground water levels relative to the subsided areas. - Resulting saturated soil <br />conditions may promote localized shifts in vegetation, with water tolerant species becoming more prevalent in <br />areas of saturated soils. Conversion of transitional sage -grass meadow and pastureland to riparian habitat is a <br />potential positive impact of the anticipated mining- related ground subsidence. <br />Stock Ponds - There are a number of small stock ponds located throughout the NMD and WMD, as shown on <br />Map 23B. The ponds are constructed of earthern materials, and are typically fed by spring runoff or rain - storms. <br />TCC has undermined and subsided similar stock ponds during mining of reserves located in the northern and <br />eastern parts of the Permit Area. No material damage to the ponds resulted from the mining activity. It is <br />anticipated that the stock ponds in the NMD and WMD will react in the same manner. If cracks develop in the <br />embarnkments, they can be repaired and regraded to maintain the integrity of the ponds. Similarly, if <br />differential subsidence results in changes in the elevation of the pond embankments relative to the containment <br />basins, minor repairs /reconstruction may be necessary to maintain water storage capacity and assure the <br />integrity of the embankments. <br />(ii) If the description of worst possible subsidence consequences, prepared in accordance with Section <br />2.05.6(6)(b)(i), determines that no material damage or diminution of reasonably foreseeable use could result in <br />the event of mine subsidence within the permit and adjacent areas, and if the Division concurs with that <br />conclusion, the application shall include a monitoring program designed to determine the accuracy of that <br />conclusion, as described in Section 2.05.6(6)(c). <br />iii) If the description of worst possible subsidence conseauences, prepared in accordance with Section <br />2.05.6(6)(b)(i). determines the material damage or diminution of reasonably foreseeable use could result in the <br />event of mine subsidence within the permit and adjacent areas, the application shall include additional <br />information as required by either one of the following_ <br />(A) A subsidence survey, as described in Section 2.05.6(6)(e); <br />(B) A subsidence control plan, as described in Section 2.05.6(6)(f). <br />RESPONSE <br />For the main mine entries, there is not expected to be any subsidence from instability of immediate roof spans or <br />induced pillar loading. The analysis to corroborate this prediction is presented in Exhibit 7, Subsidence <br />Predictions. Therefore, there will be no damage or diminution of structures or renewable resource lands above <br />the main mine development entries. <br />The analysis of worst case predictions for subsidence above production panels is presented in Exhibit 7, <br />Subsidence Predictions. It must be emphasized that these worst case predictions are extremely conservative, <br />and it would be expected that the actual subsidence will be well below these predictions <br />PR09 -08 2.05- 181.11 04/29/09 <br />