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4.0 PROJECT DESCRIPTION AND ALTERNATIVES ANALYSIS <br />4.1. DESCRIPTION OF THE CANTERBURY TUNNEL <br />The Canterbury Tunnel was constructed over several years beginning during the late <br />1920's as a community project to provide mine drainage. It was driven approximately <br />one-mile into hard rock in a relatively unmineralized area about two miles north of <br />Leadville. The tunnel collected deep-seated water and transp�rted it approximately <br />4,100 feet to a portal where the water discharged into the East Fork Arkansas River. In <br />1961, Parkville recognized that the tunnel produced high quality groundwater at a <br />constant rate, with a year-round temperature of approximately 50 degrees Fahrenheit. <br />At that time, Parkville constructed a wet well, pump station, and pipeline at the tunnel <br />portal to collect the water and pump it into the existing distribution system. From 1961 <br />through 2003, the District used the water on a continuous basis throughout the winter <br />and on an intermittent basis during the remainder of the year. Until the early 2000's, the <br />water discharged from the portal at a generally constant rate of at least 625 gpm and <br />almost all of this flow was used in the municipal water system. The tunnel discharge <br />was of excellent chemical and bacteriological quality. Throughout this period no <br />treatment other than preventative chlorination was generally required. <br />Because of the extremely cold winter conditions in Leadville, surface water supplies in <br />the Leadville area are typically at or near 32 degrees. Prior to 1961, Parkville's water <br />supply consisted almost entirely of surface water sources. Parkville operated three <br />separate plants prior to 1961 for injection of steam into the water mains. These steam <br />plants were operated on a continuous basis throughout winter to prevent freezing of the <br />town's water mains, all of which are buried at least six feet below the ground surFace. <br />With the addition of the 50 degree water from the Canterbury Tunnel in 1961 and <br />groundwater from the Elkhorn Shaft, Parkville was able to avoid severe freezing <br />problems and the steam plants were abandoned. In more recent years, Parkville has <br />constructed several wells near the East Fork Arkansas River to provide a supplemental <br />emergency source of water supply. Experience with the wells indicates that the <br />temperature of the shal�ow alluvial groundwater is around five to ten degrees colder than <br />_J W. W . Wh¢elar aod Associat¢s, Inc 5/19/2010 Final <br />— 1 Wot¢r Resouress Enginaars Page 11 <br />