Laserfiche WebLink
1100318 R0T0 0811 JRW1 43 <br />As discussed in Section 3.2, the 1994 Amendment specifies that backfilling of the excavation <br />would occur behind the quarrying and into completed portions of Area H. The report provides <br />the following reasons for the backfilling:61 <br /> “The amount of waste stored on site for use in backfilling must be limited. <br />Room available for waste storage is limited and therefore prompt backfilling <br />must be done to avoid creating ‘mountains’ of waste.” <br /> “Backfilling with waste will be needed to establish access roads in and out of <br />the Hole. Thus, the need to easily remove the mined rock requires that <br />backfilling be done and this will help limit the dimensions of the Hole that <br />will be open at any one time.” <br /> “It is not expected that any more than ¼ of the total length of the west wall of <br />the Hole will be unsupported by backfill (or unmined rock) at any one time. <br />Thus, any large scale instability that might occur would be limited in scope <br />simply because most of the west wall will either be supported by backfill or <br />by native rock yet to be mined.” <br /> “To further support the wall, the backfill will be replaced at an angle across <br />the Hole. Angled backfilling behind the mining will proceed as the Hole is <br />excavated to the south. This pattern is also advantageous for access as it <br />reduces the steepness of the road into the Hole.” <br />These statements are silent regarding the depth of backfill to be placed in Area H; they only <br />state that backfill is to be placed to support the west wall. Based on the topographic survey <br />(Appendix 46), photographs contained in Appendix 3, Appendix 6, and Appendix 8, and <br />Exponent’s subsurface exploration in Area H, backfill was placed in Area H. Based on the <br />length of Area H shown in the 1994 Amendment and 2000 Amendment, as of December 2, <br />2008, the unbackfilled, deepest part of Area H constituted less than twenty-five (25) percent of <br />the length of the west wall of Area H. This data indicates that fill was being placed behind the <br />deepest excavation into Area H per the 1994 Amendment and was at least 20 feet deep at the <br />south end of the active Area H excavation where the 25 percent limit would have existed. <br /> <br />61 Application for Permit Amendment Pikeview Quarry, Permit Number M-77-211, received by Colorado <br />Division of Minerals and Geology on June 2, 1994, page 23-24 (Appendix 12)