Laserfiche WebLink
December 23, 1999 O • Puge 2 <br />' consistent with current practice overlongwallcoalminingpanelswheresignificantsubsidenceoften <br />occurs. <br />2.2 Monument Locations for Future Mining Areas <br />' Surface monitoring locations will be established for future mining areas similarly to the plan <br />for the initial mining area shown in Figure 1. American Soda's intent is to have sufficient <br />' monitoring points for characterization of the shape and extent of a subsidence basin throughout the <br />project. Other section and quarter-section comer markers will be added to the subsidence monitoring <br />' plan as mining progresses and these markers fall within the potential area of influence of mining. <br />23 Surface Monitoring Frequency and Duration <br />' Surface monument measurements will be conducted annually. Upon reclamation of a well <br />field panel (or area), monitoring will continue until an adequate understanding of the data and the <br />' potential for subsidence is attained. At that point, American Soda could apply to the Colorado <br />' Division of Minerals and Geology (CDMG), Bureau of Land Management (BLM), and <br />Environmental Protection Agency (EPA) for modification or termination of that monitoring. <br />' 3.0 SUBSURFACE MONITORING <br />' The purpose of the subsurface monitoring is to ascertain movement of strata overlying the <br />solution cavities. A combination of time domain reflectometry (TDR) and borehole geophysical <br />' techniques will be employed for determination of subsurface movement. <br />3.1 Time Domain Reflectometry <br />' TDR will be used for monitoring subsurface strata movement. Coaxial cable for TDR <br />measurements will be installed in the first 23 of the first 26 production wells during the first phase <br />(~5 yeazs) of commercial operations. <br />TDR is an electrical pulse-testing technique originally developed by the telecommunications <br />' industry for locating faults in coaxial power transmission cables (Dowding et al. 1988). A cable <br />' tester is used to create a voltage pulse in the cable. When faults, crimps, or elongations are <br />encountered in the cable, a reflected signal returns to the cable tester as a result of the change in <br />' electrical wine properties. Knowledge of the properties of the wire permit location of cable damage <br />by measurement of travel times. <br />' Agapito Associates, Inc. <br />