PERMFILE43358 - Laserfiche WebLink

Home Browse Search

• water supply of a public system and as such cannot be classified as a renewable resource land. The Twentymile and the Middle Sandstones are the only two- (2) sandstone aquifers, which lie above the planned mining horizon. Only the Twentymile Sandstone has a wide, continuous distribution within the permit area. However, the majority of the planned five (5) year mining lies outside of or immediately adjacent to the outcrop of the Twentymile Sandstone. The Twentymile and the Middle Sandstone lie sufficiently above the "E" Coal Seam (No. 6 Mine) and the "F" Coal Seam (No. 5 Mine) so as to be situated in the zone least impacted by mining. The areas where multiple-seam mining will occur are located immediately adjacent to the outcrop of the Twentymile Sandstone. Therefore, the effects of mining- induced subsidence on the sandstone aquifers are expected to be minimal. A detailed discussion of the impacts of mining on the sandstone aquifers is presented in Section 2.05.6, Mitigation of the Impacts of Mining Operations. CEC Corporation, based on the results of a subsidence survey presented in this application, has determined that the worst possible consequences of subsidence will not result in any material damage or diminution of reasonable foreseeable use to structures and renewable resource lands within and adjacent to the permit area. CEC has prepared a monitoring program designed to verify this conclusion. The following is a discussion of the monitoring program. CEC has performed extensive subsidence monitoring at the CEC mine complex during the past several years. CEC believes that the site-specific subsidence for the CEC Mines has been well defined. However, CEC proposes to use a combination of existing and new subsidence monitoring points, as well as a program of visual observations, for monitoring subsidence impacts from the planned longwall mining on structures within and adjacent to the permit area. Monitoring and observation programs will commence approximately one (1) month prior to the time mining-induced surface subsidence, based on the projected angle of draw of 19 degrees, can impact each monitoring and observation point. The exact timing of the start of monitoring will be a function of weather conditions and site accessibility. CEC • used the existing subsidence monitoring net located above the No. 5 Mine longwall panel to monitor surface subsidence effects in the immediate area of the planned longwall mining. The existing subsidence monitoring net is shown graphically on the Subsidence Monitoring Map (Map 31). Subsidence monitoring points (Rows A, B, C, and D) located above the cap thud east full extraction room-and-pillar panels (No. 5 Mine) showed very little movement in the past and subsequently monitoring of these points was terminated in 1985. However, these points are still in place and may be used for future monitoring activities, if required. Monitoring, if required, will be resumed one (I) month prior to initiation of possible mining induced subsidence from the No. 6 Mine ("E" Coal Seam). Locations of subsidence monitoring points rows A, B, C, and D are shown on the Subsidence Monitoring Map (Map 31). New subsidence monitoring points will be established for the private residences located in Section 29 and 30 as well as State Highway 13. The monitoring points for the structures in Sections 29 and 30, T6N, R91 W, will be located at each of the four (4) corners of the residential structures. Locations for monitoring points along state highway 13 will be established following approval of the locations by CMLRD, as mining approaches the highway. These additional monitoring points will be installed at least one (1) month prior to initiation of possible mining-induced subsidence based on the projected 19° angle of draw. Monitoring of monuments shall be performed at least quarterly; commencing one (1) month prior to initiation of mining beneath any established monument or structure. In order to ensure that the monuments and structures are properly installed, they will be surveyed at least twice prior to the initiation of subsidence. Results of the monitoring program shall be submitted to the Division at least semi-annually. The subsidence monitoring program will continue until the results indicate that: 1) subsidence has not occurred, 2) subsidence has ceased, or 3) subsidence that has occurred has not caused any material damage, and the Division concurs, in writing, with these conclusions. Semi-annual reports will typically be submitted within 60 days of the end of the monitoring period, but shall in no case be submitted later than 90 days from the end of the monitoring period. Permit Renewal No 3 2.05-54 7/15/98