REP38079 - Laserfiche WebLink

Home Browse Search

0 CTL/THOMPSON, INC. CONSULTING GEOTECHNICAL AND MATERIALS ENGINEERS August 18, 1992 Colowyo Coal Company 5731 State Highway 13 Meeker, Colorado 81641 Attention: Subject Gentlemen: Mr. Rich Atkinson Mr. James Kiger Review of MLRD Correspondence West Pit and Section 16 Excess Spoil Fills, PR-Ot (C-81-019) Job No. 18,638 CTL/Thompson, Inc. was requested to review the June 11, 1992 Mined Land Reclamation Division (MLRD) response to concerns presented by the Office of Surface Mining (OSM) in letters dated March 16, 1992 and June 4, 1992. The purpose of this letter is to express our strong agreement with the MLRD conclusions which detail Colowyo compliance with each concern raised by OSM. We have previously addressed OSM concerns (durable rock; drain and filter requirements; lift thickness; density; voids and stability) in detailed reports. The MLRD response addressed each one of the OSM concerns with appropriate excerpts from our previous reports. We do not understand the lack of acknowledgement by OSM of our previous reports but agree with MLRD that the concerns presented by OSM have been adequately addressed by Colowyo. Following is a reiteration of our opinions regarding the concerns raised by OSM. The harder available sandstones are considered durable rock (refer to CTL/Thompson report dated March 1, 1991, Job No. 16,516). 2. Gravity sorting of spoil with a lift thickness on the order of 50 feet or more will provide an effective filter to prevent clogging of the drain (refer to CTUThompson report dated April 17, 1992, Job No. 18,638). An initial lift thickness on the order of 50 feet is recommended, but should not be considered an absolute minimum. A lift height slightly more or less than 50 feet could produce adequate sorting. The sorting should be monitored in addition to lift thickness to verify conditions are as anticipated. 1971 WEST 12TH AVENUE DENVER, COLORAD080204 (303)825-0777