WSP10212 - Laserfiche WebLink

Home Browse Search

Il02\Qb8 ulants as I ime, I imestone, magnesia, or sodium (Yan, 1976). Occasionally, salable sulfur byproducts may be recovered, and the residuals after treat- ment from the flue gas-scrubbing systems must be disposed of along with the soiid ash material (about 141 tonnes per megawatt generating capacity per year). In imposing residuals-modification requirements on sulfur gas- es, resultant sol id residuals are increased by 10 to 12 times (I. C. James and others, written commun., 1976), and resultant environmental impacts merely are transformed to another environmental medium (Reiquam and oth- ers, 1975). Ash and dewatered sol ids from a "hot-side" precipitator scrubbing flue-stack gases at the Hayden power plant (fig. 1) are trucked and dumped into excavated pits in a nearby mine that suppl ies coal to the plant. Possible ground-water contamination 'resulting from the disposal of these sol id wastes warrants further monitoring and study. Waste-heat dis- sipation through cool ing towers generally requires soma treatment of the mineral ized cool ing waters. Biocides to control biological growth and oth- er chemical agents to control scal ing in cool ing towers must be disposed of. Various trace metals in coal combustion are transformed into solid and gaseous residuals (Klein and others, 1975). For example, prel iminary data from a streamflow-quality reconnaissance survey (Steele and others, 1976a) give evidence of anomalously high concentrations of copper in the bottom sediments of a small tributary stream to the Yampa River receiving intermittent discharge effluents from the Hayden power plant. Thermally polluted plant discharges are not permitted under current effluent stand- ards; however, the possibil ity of controlled liquid-residual discharges still exists. The resulting effects of thermal discharges on stream sys- tems may be evaluated with the aid of stream-temperature model ing tech- ni ques (Stee Ie, James, Bauer, and others, 1976b). Consumptive-water-use estimates for electric-power generation include water used for boiler feed, cooling, flue-gas scrubbing, and ash disposal. Water-inflow rates for a power-generation plant producing 1,200 megawatts with no flue-gas scrubbing is estimated to range between 0.53 and 1.17 billion cubic metres per year for condensor and boiler-feed water require- ments, depending upon' the particular cool ing system used. A flue-gas scrubber and particulate-precipitation system increases plant water-inflow rates by approximately 6 percent (I. C. James and others, written commun., 1976). The major consumptive use of water in a power-generation plant is for evaporative cool ing of condenser water. Annual consumptive use is about 0.24 mill ion cubic metres for the other three systems (Freudenthal and others, 1974). These losses, compared with plant inflow of water, represent2 percent or less of ,the water withdrawals, so that most of the water can be recycled in the plant or reused elsewhere in the basin. If once-through cool ing were used without use of some kind of impoundment- recycl ing system, water-inflow rates cited above for a single l,200-mega- watt plant could represent as much as 60 percent of the mean annual flow from the entire Yampa River basin (1.9 bill ion cubic metres). . Coal Gasification For demonstrating potential impacts of coal-gasification in the Yampa River basin, the residuals-management consequences of a SYNTHANE process plant are being used. Impacts of other proposed coal-gasification process- 8