OCR Text |
Show RECOVERY OF UNDERGROUND WATER. 37 City from June to September, inclusive, is 6.5 miles an hour and for the entire year averages only 5.9 miles, the natural conditions are not very favorable for this form of power. Steam pumps are used only to a limited extent. The Bingham Consolidated Company has three 3- inch wells 250 to 300 feet deep in which the water rises to within about 70 feet of the surface ; 125 gallons per minute are reported to be supplied by each, the water being raised by compressed air. Another instance of successful pumping is at the brickyard in sec. 29, T. 1 S., R. 1 E., where 40 gallons a minute are reported to be obtained from a well 30 feet deep. Gasoline for pumping has not been much used. Electric power can be cheaply developed in the canyons and affords a valuable asset. In the valleys of Utah Lake and Jordan River pumping on a large scale has not yet been resorted to. There is, however, a considerable quantity of water within easy reach of the surface which probably will not much longer remain unused. Underground water is recovered in exceptional circumstances by means of subsurface dams, or similar contrivances, which impound the underground supply. In unconsolidated materials, in order that this may be successfully accomplished, certain conditions are necessary. Practically impervious bottom must exist within easy reach of the surface to prevent excessive lowering of the ground- water level, and competent side walls, not too far apart, should be present to intercept lateral escape. The presence of the necessary conditions can be determined only by prospecting, and the practicability of such structures is an independent question, but because of the value of water in the area under consideration their feasibility should be investigated. Possible locations of subsurface dams are suggested by rock walls at the mouths of the narrow canyons, where borings in search of suitable bottom should be made. Tests of the amount and porosity of the valley filling at and above the mouths of the canyons, together with measurements of the velocity of the underflow, would indicate the quantity of available underground water. On Emigration Creek, for instance, the comparatively low run- off, suggesting an unusual amount of under drainage, and the quantity of water obtained from the inefficient city trench invite further testing of the possibilities. Below the mouths of the canyons in the several creek valleys favorable conditions also may be discovered by the drill to warrant the construction of infiltration galleries. In the section devoted to geology it is stated that the rocks of this region are more or less disturbed and broken, and an important part of the precipitation on the mountains finds its way into the bed rock. The water occurs in the small interstices or pores which are present in all rocks, in larger. spaces such as fissures or solution channels, and along joints, bedding planes, and igneous contacts. As would be expected, less water is found in the Oquirrh Mountains, than in the Wasatch. Bingham is a dry camp, though more or less water is encountered in the workings, while the mines of Park City are wet. The Ontario tunnel, which drains most of the large mines of the latter district, is stated by J. M. Boutwell to discharge from 6,000 to 9,000 gallons a minute. Considerable water is being recovered by tunnels driven into bed rock along the base of the mountains. In some instances the site of the tunnel marks the presence of a former spring, as, for instance, Wadleys, near Pleasant Grove, and those in Butterfield Canyon. But in one, the Dalton and Lark tunnel, east of Bingham, water in quantity was not encountered until several thousand feet of rock were penetrated. Another method of recovering water from bed rock is suggested by the structure of the mountains southeast of Salt Lake City. It will be recalled from the outline of the geology that a great syncline, modified by local undulations, is there developed, whose axis extends along the valley of Emigration Creek. The general structure is favorable for the occurrence of artesian water, but there are unfavorable complications. The rocks are chiefly compact limestones, the general disturbed and fissured conditions tend to relieve the pressure on the interstitial water, and the Wasatch fault has cut across the strata. Nevertheless, it is possible that locally the red sandstones contain water under pressure, but because of the limited intake area a large supply is not to be expected. |