CRBSCP - Paradox Valley Unit - Title II
General
The Paradox Valley Unit is located near Bedrock, Colorado, about 10 miles east of the Colorado-Utah state line and about half-way between Grand Junction and Cortez, Colorado. The Dolores River picks up an estimated 205,000 tons of salt annually as it crosses the Paradox Valley, primarily from the surfacing of natural brine groundwater. The Paradox Unit is designed to prevent this natural salt load from entering the river and degrading the water quality of the main stem of the Colorado River. The unit intercepts the brine groundwater before it enters the river and disposes of the brine by deep well injection. Major project facilities include a brine production well field, brine surface treatment facility, injection facility, a 15,932 feet deep injection well, and associated roads, pipelines, and electrical facilities.
History
The Paradox Valley was formed from the collapse of a salt anticline, one of five in the southwestern Colorado - southeastern Utah area. Formation of the anticline began some 250 million years ago when the emergence of mountainous uplifts on each side of the area placed intense lateral pressures on the intervening sedimentary formation, resulting in faulting and fracturing along weak axial zones. Relaxing of the lateral stresses combined with the weight of the overlying strata, allowed a deeply buried layer of salt-rich material to flow upward into the faulted area creating the anticline. As the pressures eased, the crest of the anticline gradually dropped downward in fault blocks. Throughout this process, the Dolores River stayed in its original course and in combination with other erosional forces, removed the collapsed materials to form the valley. The Dolores River now bisects the valley, thus the name, Paradox Valley. The valley is underlaid by a bed of salt extending from near the surface to a depth of approximately 14,000 feet. Contributing to the collapse of the anticline has been the constant dissolution and removal of the underlying salt bed by groundwater. This process is still active and contributes the approximately 200,000 ton of salt annually to the Dolores River.
Construction
The Paradox Valley Injection Test Well No. 1 was drilled to a total depth of over 16,000 feet and completed at a depth of 15,932 feet during the period from November 1986 through December 1988. Surface treatment and injection facilities were completed in 1990. The brine production well field was previously developed during the verification program. Injection testing began in July 1991 and continued through March 1995. Geochemical studies conducted during the testing program indicated the possibility of calcium sulfate precipitation occurring in the injection zone and as a result, a freshwater treatment plant was constructed to supply water to dilute the brine by 30% before injection. A pilot test program to evaluate the feasibility of using nanofiltration to remove the sulfate from the brine and allow the injection of 100% brine is currently underway. Due to the extremely corrosive nature of the brine, a multitude of problems were encountered during the testing period. However, in 1995 it was determined that deep well injection was a viable method of disposal and the Unit was converted to a permanently operating facility including the replacement of the test injection pumps with 4 new quintuples pumps. A seismic monitoring network was installed prior to completion of the injection well to obtain background seismic activity and to monitor activity that would occur as a result of brine injection. The seismic data is processed at Reclamation`s Denver Technical Center. Facilities have been installed and mechanical tests performed. Numerous mechanical and electrical problems with the facilities have been identified and solved. Several new technologies were developed to overcome the extremely high pressures created by the injection pumps. Under normal operation, the Paradox Unit averages the injection of about 14 to 14.5 million gallons of brine per month. This results in the disposal of about 10.2 to 10.6 thousand tons of salt per month or up to about 128 thousand tons of salt per year. The Paradox Unit removes 128,000 tons of salt per year, for a total capital cost of 67,400,000 and an annual O&M cost of $2,800,000--for a cost of $71 per ton. http://www.usbr.gov/dataweb/html/basinwidescp.html
Plan
The Paradox Valley Unit is in southwestern Colorado along the Dolores River. The Paradox Valley is formed by a collapsed salt dome. Groundwater in the valley comes into contact with the top of the salt formation, where it becomes nearly saturated with sodium chloride. Saline concentrations have been measured in excess of 250,000 milligrams per liter, by far the most concentrated source of salt in the Colorado River Basin. Groundwater then surfaces in the Dolores River. Reclamation studies show that the river picks up more than 205,000 tons of salt annually as it passes through the Paradox Valley. The plan consisted of: Constructing a series of shallow brine production wells paralleling the Dolores River next to known brine inflow areas Pumping the wells at a combined rate of 5 cubic feet per second to intercept the brine Disposing of the brine by evaporation in the 3,700 surface acre Radium Evaporation Reservoir. Transporting the brine via a 21-mile long pipeline to Dry Creek Basin
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