| OCR Text |
Show The major obstacle to the erection program, aside from the steep grades, was sand. This was complicated somewhat by there being no transition zone between sand and rock. It was always rock or sand, with the depth of sand varying from zero to undetermined depths . The drive house sub bases are massive concrete blocks, amply proportioned to withstand the turning forces created by stopping a fully loaded conveyor. The conveyor stripper supports are concrete footings on H-section piles, depending on the depth of sand. CR Steel Used in Structures A detailed economic analysis was prepared to determine the advis- ability of using a special corrosion resistant steel. In some instances a lighter structural shape could be substituted, because the corrosion resisting alloying elements also imparted higher strength to the steel. Based on the results of this study, and as an experiment to combat severe corrosion, all structures outside of the drive house buildings were fabrica- ted of a low alloy high strength steel containing nickel and chromium. At present this steel requires painting half as often as mild steel, and the experiment is considered successful. To avoid a constant head-on encounter with the marching sand dune that crosses Flight Four, the conveyor was arched in this area to allow free movement of the dune. This arch would permit movement of clean-up tractors in case of excessive drifting. The dune does drift, but in a loca- tion some distance from the conveyor. It continues to build up to a height where the conveyor gallery and the dune upset the normal path of the steady and strong wind, and this turbulence sweeps the sand under the conveyor, making the dune self-cleaning. The dune in its march northwest intersects the conveyor access road and requires the daily service of a motor grader. System Operates Round-the -Clock A. summary of construction costs for the system, exclusive of roads, is as follows: Labor (U.S. & Peruvian, incl. taxes) $ 174, 000 Material & equipment (incl. frt. & duties) 1,910, 730 Construction equipment operation 61, 780 Subcontract charges 44, 770 Indirect charges and engineering 849,920 TOTAL S3, 041, 200 |
