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<br />~ <br />~ <br />~ Modified In-situ Retorting of Oil Shale. Two major water treatment <br />~ and disposal problems present themselves in the modified in-situ retort- <br />ing of oil shale, assuming that the industry is located in the Piceance <br />Creek Basin of Colorado. The first is treatment of the brackish mine <br />drainage water that may be encountered (up to 18 acre-feet per year per <br />57,000 bbl/day facility). Part of this water would be treated for use in <br />the plant, while any excess drainage water would have to be either re- <br />injected or treated for discharge to a surface stream. Associated with <br />this treatment is the disposal of large volumes of concentrated waste <br />equal to about 15 percent of the water to be treated. The second major <br />problem is treatment for internal plant use of the large quantities of <br />foul 'water generated in the retorting process. <br /> <br />There are major difficulties in assessing treatment and disposal <br />costs at this time because detailed information on the quantity, and <br />particularly the quality, of the mine and retort waters is not known <br />with any degree of certainty. All estimates must therefore be used with <br />great caution as they can only be considered educated guesses in a number <br />of instances. <br /> <br />With this caveat in mind, it is estimated that wastewater treatment <br />costs would run anywhere from about 5~ to 14C per million Btu of output <br />depending upon the quantity and quality of any excess mine drainage water. <br />This compares with a total cost for producing crude shale oil of at least <br />$2.50 to $3.00 per million Btu. <br /> <br />1-18 <br />