| 翻訳と辞書 |
| Redridge Steel Dam ： ウィキペディア英語版 |
Redridge Steel Dam
The Redridge Steel Dam is a steel dam across the Salmon Trout River in Redridge, Houghton County, Michigan. Completed in 1901, it is a flat slab buttress dam constructed of steel, a relatively rare material for construction of dams, which are typically earthenworks or masonry. Most sources indicate it was one of only three such dams constructed in the United States, the other two being the Ashfork-Bainbridge Steel Dam (1898, Arizona) and the Hauser Lake Dam (1901, Montana), the last of which failed within a year of construction.
==History==
In 1894, prior to the construction of the steel dam, the Atlantic Mining Company built a timber crib dam across the Salmon Trout River. The dam created a reservoir which supplied water to the Atlantic stamp mill which extracted copper from ore-bearing rock. With the growth of the Atlantic stamp mill and the construction of the Baltic Mining Company mill nearby, this reservoir proved to be insufficient, and in 1901 the steel dam was built. It was designed by J. F. Jackson and built by the Wisconsin Bridge and Iron Company. The old timber crib dam remained in place, submerged, upstream of the steel dam. A system of spillways, sluices (or ''launders'' as they are referred to in contemporary texts), and pipes brought water downhill to the stamp mills. The dam itself measures 74 ft (23 m) high at its center and extends for a length of 1,006 ft (307 m) across the river. Access to the reservoir was shared by the Atlantic and Baltic mines, which had a common board of directors.
The dam operated for several decades, until the mines closed. After that time, the dam was no longer maintained. On Easter morning of 1941, the spillway behind the dam broke, causing a flood. There was little damage to the steel part of the dam, but with the mining operations stopped, the dam owners had the spillway valves opened. However, there were still incidents of overtopping,〔As illustrated in this: ( overtopping image )〕 and the Copper Range Company (successor to Atlantic Mine Company and owner of the dam) had large holes cut in it in 1979 so that it would not retain water. This lowered the level of the reservoir, revealing the earlier timber dam.〔The dam in this illustration of the Dam article is actually the earlier timber crib dam replaced by the Redridge Steel Dam〕
Ownership of the dam was transferred to Stanton Township in 1992. Fears that the timber dam might fail and Michigan's Department of Environmental Quality considering the dam a "significant hazard" forced the township to consider renovating the dam in 2001. Five options were proposed for a long-term fix for the dam. These options ranged from repairing the steel and wooden dams for $311,000 to restoring/ reconstructing the entire structure for over a million dollars. Stanton Township could not afford to do any of the proposed options, so another option was sought out. A short term fix was found to make the dam safer. The upper 13 feet of the wooden structure was removed in 2004 to bring the water level down and relieve some of the pressure. A more permanent repair is still needed. A recent study by a team of students from Michigan Technological University determined that both dams are likely to remain safe for the foreseeable future.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Redridge Steel Dam」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|
