Laserfiche WebLink
Power Substations 1 and 2 <br />Power Lines <br />• City of Florence Water Line <br />Telephone Communications Lines <br />Structures associated with EFCI's mining and related activities, including office, shop, <br />warehouse, preparation plant, and loadout facilities will not be undermined, and therefore, <br />will not be affected by any resulting subsidence. The configuration of potentially affected <br />structures within the area of concern is illustrated by the Mine Surface Facilities Map, <br />(Map 18). <br />EFCI's subsidence inventory does not delineate any renewable resource lands within <br />potentially affected areas. <br />Probable and Worst-Case Subsidence Based on the subsidence report prepared by <br />RMG in 1983 for Dorchester, both the maximum expected probable and worst-case <br />expected subsidence ranges were predicted. RMG predicted maximum expected vertical <br />subsidence, corresponding to retreat extraction, ranging from 1.46 feet to 5.85 feet. These <br />predictions apply to Southfield's overall mine plan within the permit area. Where pillars are <br />• left (development extraction only), RMG predicts aworst-case vertical subsidence ranging <br />from 2.60 to 4.36 feet. <br />The RMG subsidence predictions and subsidence control plan is currently being used by <br />EFCI and has proven to be accurate. Actual subsidence monitoring data collected over <br />the past twelve years by both Dorchester and EFCI indicate vertical subsidence ranging <br />from 0.03 and 3.06 feet, well within the ranges predicted by RMG. Actual subsidence data <br />can be found on Table 1, High Resolution Grid, and in the Semi-Annual Subsidence <br />Monitoring Reports contained in Exhibit 23 and subsequent reports submitted to the <br />Division. <br />Based on worst-case subsidence projections, the RMG report determined that some <br />material damage or diminution of reasonable foreseeable use could result. Since the <br />potential for damage exists, this damage has been evaluated under applicable provisions <br />of Sections 2.05.6(6) and 4.20. An evaluation of material damage or diminution of <br />reasonable foreseeable use for the Southfield Mine area was determined on a site by site <br />or structure by structure basis. These estimates continue to be valid for the <br /> <br />2.05.6-56 Revised 4/3/96 <br />Technical Revision No. 24 <br />