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<br />SALINITY LOADING TO THE COLORADO RIVER <br /> <br />Q <br />N Introducti on <br />0'. <br />r' As part of the geothermal reservoir testing program performed <br />for the Redstone Corporation, an analytical model of the <br />reservoir was developed. Actual test data was used to calibrate <br />this model, which was used to predict drawdowns anywhere in the <br />reservoir at various discharge rates and pumping times. Using <br />accepted relationships between drawdown and discharge, changes <br />in discharge of various documented thermal springs were <br />calculated. These calculated changes compare favorably with <br />observed reductions in spring flow during the reservoir test. <br /> <br />r <br />" <br />r. <br /> <br />Using both observations and calculated effects to the existing <br />geothermal system, we conclude that there will be no net <br />salinity increase in the Colorado River due to discharge from <br />the Redstone geothermal well. The "no net salinity increase" <br />agrument is expanded and documented in this section. <br /> <br />Analytical Model <br /> <br />THEORY <br />The Theis well equation, one of the most widely used equations <br />in hydrogeology, is the basis for the analytical model used in <br />this study. The equation predicts drawdown from a discharging <br />well in an infinite, homogeneous, confined aquifer. By using <br />the theory of superposition, one can simulate variable discharge <br />wel,ls or springs, boundary conditions, and injection wells. The <br />theory of superposition says that the drawdown at a point in an <br />aquifer that is affected by several wells (or spings) is the sum <br />of the drawdowns for each of the wells at that point. By using <br />image well theory, various types of hydrologic boundaries, <br />including discharge and recharge, can be simulated. Most <br />hydrogeology texts discuss the use of these theories in <br />analytical analyses (Walton, 1970; Davis and DeWiest, 1969; <br />Freeze and Cherry, 1979). <br /> <br />A more detailed discussion of the model, its equations, and its <br />operation is in Appendix A. <br /> <br />MODEL SET-UP AND CALIBRATION <br />All known discharging points, including springs, seeps, and <br />wells (Redstone), were represented by discharging wells with an <br />assigned discharge. The assigned locations and discharges for <br />these points were based on work by Barrett and Pearl (1978). <br />These values are listed in Table 1 and their locations shown on <br />Plate 1. In addition to the documented springs, two additional <br />springs were included with estimated discharge. The addition of <br />these springs is based on field observations. At several <br />locations, one well was used to simulate two or more closely <br /> <br />,\ <br />, <br /> <br />1 <br /> <br />I 1\ V' <br />I <br /> <br />l. "-< <br />