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Davidson Ditch is a conduit built in the 1920s to supply water to gold mining dredges in central Alaska. It was the first large-scale pipeline construction project in Alaska, and lessons learned in its construction were applied to the building of the Trans-Alaska Pipeline System. It is eligible for inclusion on the National Register of Historic Places, but has not been listed due to a lack of information. Despite this, the remains of the conduit are partially protected by its inclusion in the White Mountains National Recreation Area. ==Planning and surveying== In 1902, the discovery of gold north of the Chena River in central Alaska drew thousands of people who hoped to strike it rich. The town of Fairbanks, Alaska was founded as a result of the rush to mine ore. By 1910, most of the valuable claims had been staked and excavated by placer miners and people excavating mines by hand. Gold production declined, and by 1920, less than $1 million (1920 dollars) in gold was being produced annually.〔Wold, Jo Anne. "Digging the Davidson: An engineering marvel", ''Fairbanks Daily News-Miner''. July 14, 1984. Golden Days section, Page 2.〕 Mining engineer Norman Stines observed the success of gold mining dredges near Nome and believed the same technique could be applied to Fairbanks. The problem was the lack of available water in the gold-mining areas. Dredges float on barges, and hydraulic mining, which uses water under pressure to remove overburden, requires a lot of water. The obvious solution was to construct an aqueduct of some kind to divert water from nearby rivers, but no aqueduct of the needed scale had ever been built in Alaska.〔 Stines contacted surveyor and engineer James Davidson, who had built the Miocene Ditch that allowed the use of dredges near Nome. In 1920, when Stines arrived in Nome, Davidson was working for a series of hydraulic mining operations and for a company supplying drinking water to Nome. Davidson was enthusiastic about the idea, and he traveled to Fairbanks in 1923 to study the water situation. One year later, Stines began drilling. His operations caught the attention of W.P. Hammon of the American Exploration Co. (later the United States Smelting, Refining and Mining Company). Hammon had been intrigued by the idea of a similar project and first examined it in 1907, but it was not cost-effective at that time. By 1923, the Alaska Railroad was in operation to Fairbanks, greatly cutting transportation costs, and coal from mines near Healy opened the door for the expansion of steam power in the area.〔 Hammon began negotiations with Stines, and together they formed the Fairbanks Exploration Company (FE Co.), a subsidiary of United States Smelting, Refining and Mining Company. The new company paid for the project and supervised construction.〔Gedney, Larry. ("The Davidson Ditch" ), Alaska Science Forum. August 29, 1983. Accessed June 27, 2009.〕 Stines was named general manager of the new company, and he contacted Davidson to head a 22-man survey crew to determine the best way to get water to the mining sites. Davidson's survey team determined that the best way to get sufficient water was to construct a conduit to divert water from the Chatanika River. In July 1924, Davidson's team began mapping the route.〔 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「Davidson Ditch」の詳細全文を読む スポンサード リンク
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