GENERAL46014 - Laserfiche WebLink

Home Browse Search

.~ .= IX. Subsidence Control 1. The applicant has proposed a subsidence control plan in accordance with Rule 2.05.6(6) and has committed to adopt all measures in order to reduce the likelihood of subsidence, prevent material damage, or mitigate the effects. The Division proposes to approve the plan (4.20.1(2) and 4.20.3(1)). (See pages 4-75 through 4-77 of the permit). 2. The applicant has a proposed subsidence monitoring program, in accordance with Rule 2.05.6(6)(c), designed to determine the commencement and magnitude of subsidence movements should they occur. Figure A, Appendix 4.6-1, depicts the location of monuments to be installed and structures to be monitored within the permit and adjacent area. X. Operations on Alluvial Vallev floors Information on alluvial valley floors is contained in Section 5.1 of Volume I and figures 5.1-1, 5.1-2, and 5.2-2 of the application. The applicant identified unconsolidated streamlaid deposits along the Colorado River, Alkali Creek, and South Canyon Creek. South Canyon Creek is not hydrologically adjacent to the proposed mine for this permit term; therefore, it will not be considered in this alluvial valley floor (AVF) determination. Alkali Creek and the Colorado River will be discussed separately below. Alkali Creek Only a small portion of the proposed permit area is within the Alkali Creek drainage basin. The permit area within this drainage is limited to approximately three miles of light use road used to monitor well SK 3.75. The applicant submitted very little AVF information on this drainage. Therefore, the Division must conservatively assume that the unconsolidated streamlaid deposits in Alkali Creek comprise a significant alluvial valley floor. Alkali Creek Findings 1) None of the light use road is located within the alluvial valley floor. Based on that fact, the Division finds that the proposed operation will not interrupt, discontinue, or preclude farming on the alluvial valley floor. 2) Surface waters which supply the alluvial valley floor are derived from the Alkali Creek drainage and Garfield Creek. Water is diverted from the Garfield Creek drainage through the Sykes and Alford trans-basin ditch into Porter Reservoir. The water in Porter Reservoir is then directed to Alkali Creek through the Roderick ditch as needed. Other small reservoirs are located in the lower reaches of Alkali Creek. -26-