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<br />, <br /> <br />The following sections illustrate the kinds of preliminary investigations <br />that should be completed before a project 1S recommended for funding and <br />an engineering design made. Sections C.l. and C.2.illustrate two <br />technically feasible projects to control saline springs - the first is <br />clearly economically feasible, the second is not clear. Section C.3. <br />illustrates a successful well plugging. <br /> <br />C, Case Studies <br /> <br />1. Diffuse" Point Discharge (Salt Creek) Spring <br /> <br />Salt Creek drains Sinbad Valley and is tributary to the Dolores River. <br />The mouth of Salt Creek is located nine miles southeast of Gateway, <br />Colorado. Base flow is furnished by several small springs at or" near <br />, the mouth of Sinbad Valley. High flow comes from snowmelt and rainfall <br />runoff. Surface flow in Salt Creek is ephemeral, drying up in the hot <br />summer months; subsurface flow is perennial. Discharge from the saline <br />springs at the mouth "of Sinbad Valley is perennial, yielding approxi- <br />mately 100 gallons of water per minute (gpm) or 160 ac-ft per year. <br />Concentration of salts in this water is 61,200 mg/l, resulting in a <br />total salt yield of 13,317 tons annually. If the flow from these <br />springs could be kept from entering the Dolores River, this action would <br />result in a reduction of salt concentrations of 1.11 mg/l at Imperial <br />Dam. <br /> <br />W <br />CJT <br />l'V <br />f\) <br /> <br />*"" <br /> <br />A reconnaissance of Sinbad Valley was made to locate a suitable site for <br />evaporation ponds. A fairly large area of relatively flat ground was <br />found on private land just south of the proposed collection site. <br />Figure 2 shows one proposal for location of facilities needed to control <br />salt using evaporation ponds. This procedure would require a collector <br />made up of a barri er dam, a sump, and a pumpi ng pl ant. The co 11 ected <br />water would be pumped up-slope a short distance through a pipeline and <br />evaporated in four ponds. Thi s site woul d reduce the 1 ength of the. <br />pipeline to a minimum. <br /> <br />The cost-effecti veness and benefi ts are computed us ing the foll owing <br />information: <br /> <br />Detailed Cost Analysis <br /> <br />Assume: <br /> <br />$425,000 = Cost of 1 mg/l rise in salinity at Imperial Dam (economic <br />detriment value). <br /> <br />1.11 mg/l = Benefit from the salinity control system. <br /> <br />20 <br /> <br />-fed- <br /> <br /> <br />J <br /> <br />$;.<: "~'--'~"- -'~ <br />