WSP07805 - Laserfiche WebLink

Home Browse Search

a N ~ N CHAPTER IV PROBLEM IDENTIFICATION AND QUANTIFICATION ACTIVITIES " the Marland Well were the highest, ranging between 86' F to 104' F, while shallow bedrock units had temperatures in the 57' F to 75' F range. These temperature differences can be attributed to natural geo- thermal gradients and the longer length of time required for warmer water to move through cooler formations. The upper Morrison aquifer, believed to be the primary source of saline water in the springs, aver- aged about 70' F except where it is affected by surface conditions. All bedrock units reflected a similar pH of about 7.6 except the lower Dakota which had a pH of 5.9. Although no data were available to ex- plain this difference, it is apparently related to the local geochemis- try. The water quality of the alluvial aquifers in the area varied greatly depending on the source of the water. The alluvial aquifer south of the river was unaffected by saline water from Meeker Dome. The alluvial aquifer on the southeast flank of the dome was invaded by saline water discharging out of the nearby Dakota Sandstone and, con- sequently, acquired similar saline water quality. Problem Identification and Quantification As previously discussed, numerous variations in water movement have occurred in the wells and seeps in the vicinity of Meeker Dome over the last 100 years; however, the variations were based on observation and historical accounts, and no scientifically valid data on salt loading were collected until the 1960's. Beginning in May 1962, water quality data were collected at stations on the White River both above and below the dome as well as areas near the Meeker Well and several areas on adjacent ranches upstream. Minor variations generally exist among these sites due to evaporation and dilution. Flows from Meeker Dome are not the only source of salt being added to the White River. Natural erosional processes upstream of the dome, for instance, probably contribute more salts than the dome itself. Similar processes occur along streams tributary to the White River. Return flows from agricultural lands also contribute salts. c Return flows, drainages, seeps, natural flows, and other sources contribute approximately 70 cfs to the White River in the reach between a point just above the dome and the U.S. Geological Survey station 10 miles below Meeker. The data were carefully analyzed to separate the contribution from the dome itself, since it does not produce a large portion of the total river flow. In the 3 years (1979-8l) prior to reentering the oil wells as part of the unit verification activities explained in the next chapter, about 2l,400 tons of salt were estimated to have entered the White River from the dome annually. The average flow of the river immediately above the dome was approximately 520 cfs, with an average TDS concentration of 232 mg/L representing a salt loading of 118,900 tons annually. The average 11