OCR Text |
Show groundwater development. A groundwater project was formulated for the Salt Lake County area to determine a representative cost for developing a groundwater supply. ( a) Description of the Alternative Figure H- l shows that good quality groundwater is available on the east side of the valley. This would require the well field to be located on the east side of the valley, with a collection system and high pressure pipeline provided to convey the water from the well field to the areas of demand on the west side of the valley. According to the analog model studies discussed in a Utah Department of Natural Resources publication,-^ 2 groundwater withdrawals greater than present withdrawals in the order of 30,000 acre- feet annually would cause depletions to flowing wells in the order of U, 300 acre- feet and depletions to the Jordan River in the order of 8,800 acre- feet annually. It is assumed that about 60 percent or 2,600 acre- feet of the U, 300 acre- feet of flowing well depletion is high quality water and must be replaced by high quality water. The remaining 1,700 acre- feet of flowing well depletion, as well as the 8,800- acre- foot depletion to the Jordan River, must be replaced from a low quality source. With the existing independent groundwater systems expanding their production by about 12,000 acre- feet annually, the proposed alternative well development must supply the 18,000 acre- feet as well as the 2,600 acre- feet of flowing well depletions. Well discharge would need to meet the municipal demand pattern, with a maximum monthly demand amounting to 16 percent of the annual demand. Therefore, the peak discharge would be 3,300 acre- feet or about 5^ c. f. s. A minimum standby capacity of 50 percent should be provided to compensate for well failure ( wells drying up), sanding in, or pumps breaking down during a drought period. ( Some engineering consultants have recommended as much as 100 percent standby capacity.) The required capacity is therefore about 80 c. f. s., based on 50 percent standby capacity. The independent systems presently have only a 22 c. f. s. standby capacity for a 125 c. f. s. production capacity. Of this amount, 50 c. f. s. comes from numerous small flowing wells. Additional capacity should be provided. Because many of the wells in these systems have relatively small yields ( l c. f. s. or less), the failure of several wells doesn't cause as large a reduction in production 492 |