REP11120 - Laserfiche WebLink

Home Browse Search

~~. t CTL/THOMPSON, INC. CONSULTING GEOTECHNICAL AND MATERIALS ENGINEERS August 12, 1981 Empire Energy Corporation 5900 South, Yosemite Street • '- Suite 160 . ,',Englewood, Colorado 60112 .., Attention:. Mr. Rick Mills :'Subject: Revised Construction Plans Coal Processing Waste Bank Empire Energy Mines No. 5'and 9 Craig, Colorado • Sob No. 7372 ;Gentlemen: We have revised construction plans for a coal Processing Waste Bank to be constructed at Empire Energy Mines No. 5 and 9 near (:raig, Colorado.' Construction revisions were necessary due to a variance between actual field conditions and large scale topography used for initial design. The coal processing waste bank construction revisions were done to meet performance standards specifications of Section 4.10 of the Colorado Mined Land Reclamation Board. 'The bank is to be ,constructed near the top of a local hill within the permit boundary. Topographic maps indicate that slopes in the area of planned construction are generally less than 6:1 (horizontal to verti- cal). Most of the area surrounding the waste bank slopes downward away .:from the bank at relatively gentle grades. The site was previously used as a gravel source by the County for maintenance of roads. The material was developed from a conglomerate formation and excavate(i in an erratic 'pattern. Apparantly, when highly cemented material was encountered, the excavation operation was shifted to other areas of the p•it. This re- sulted in a very uneven surface. Our original design was based up:~~~. ~. topography that did not truly reflect the local variations of the sur- face. As part of this design, new mapping was obtained by cross sec- . tions in the proposed construction area. Additional test. pits were excavated to evaluate the surficial deposit. With this additional data, the proposed pile design was revised to more accurately reflect field conditions. Naul roads are present west and south of the planned con- struction area. Surface diversion ditches have been designed around the perimeter of the toe of the bank to intercept surface runoff from the pile in accordance ' with 4.10.3(2). The surface diversion ditches will convey water co1- ,lected to .surf ace ditch HR-D4 and eventually to sedimentation pond HR-Pl ~~. ~~ ~ 1971 WEST 12TH AVENUE DENVER, COLORADO B020n (3037825-077?