Endangered Species Biological Assessment for the Dirty Devil River
Total Page：16
File Type：pdf, Size：1020Kb
ENDANGERED SPECIES BIOLOGICAL ASSESSMENT FOR THE DIRTY DEVIL RIVER UNIT DECEMBER 1984 PROJECT SETTING Location The Dirty Devil River Unit is located in south central Utah. The unit includes the major tributaries of the Muddy Creek, Fremont River, Dirty Devil River and their tributaries. The unit area covers 4,300 square miles and includes portions of Sanpete, Sevier, Emery, Wayne, Piute, and Garfield Counties. The Bureau of Land Management (Bu) admin- isters approximately 75 percent of this land. The remaining area contains a large portion of Capitol Reef National Park, a small section of Glen Canyon National Recreation Area, portions of Fish Lake, Dixie and Manti-LaSal National Forests, and sections of state and private land. Elevations range from about 3,600 feet at the mouth of the Dirty Devil River to 11,500 feet in the mountain ranges at the head of the drainage basins. Purpose The purpose of the Dirty Devil River Unit is to reduce salinity in the Colorado River. The Dirty Devil River drainage contributes an average of approximately 155,000 tons of salt annually to the Colorado River, increasing the salinity concentrations of the river at Imperial Dam by approximately 15.5 mg/L of salt. The objective of the unit is to remove as much of the salt loading from the Dirty Devil River as is eco- nomically justifiable. Plan Description Although a variety of plans were investigated, saline water collec- tion from both Emery South Salt Wash and Hanksville Salt Wash remained the only plan considered acceptable (Figure 1). This alternative would collect base surface and subsurface flows from both washes. A total of 20,600 tons of salt annually would be removed by collecting saline water at a continuous rate of 2.75 cfs. This removal would be from both washes and would require separate collection and disposal facilities. Collection would be accomplished by alluvial wells. The collected saline water would be disposed of by deep well injec- tion'. The Coconino sandstone geologic formation is considered the most favorable disposal reservoir. One well would handle the flow at each wash. This formation is between 3,000 and 4,000 feet deep in both washes. It is isolated from fresh water aquifers above and below by very low permeable formations. The Coconino formation has adequate Teservoir capacity to contain the saline water for over 50 years. Permeabilities projected are high enough to allow injection at accept- able pressures. Well drilling would be standard techniques used for the 1 petroleum industry. Before injection, the saline water would be fil- tered- to remove the minor amount of suspended sediment. Algacide and stabilizing chemicals would be added to reduce scaling and algae growth. This process plus the high pressure injection pumping would be housed in one location in each wash. The injection wells can be located in any convenient site adjacent to collection and treatment facilities. All facilities would be located on land presently owned by the Federal Government and administered by the ELM. Access to both washes would be maintained by upgrading existing roads. Facilities would be electrically powered. Existing private power transmission lines would be extended .along existing roads. Powerline locations would be established based on the Bureau of LanA Management visual resource mana- gement plan. Hanksville Salt Wash Collectable water is estimated to have a concentration of 5,900 mg/L of total dissolved solids (TDS) and a continuous flow of 2.5 cfs. This is a combination of surface and subsurface flows. This water would be collected by constructing a series of alluvial wells to obtain underground flows as well as surface flows. The alluvial pumping facilities were sized with a simple groundwater assumption: the maximum or projected drawdown from each well was limited to 30 feet. This criterion limits each well to approximately 100 gpm and approxi- mately 2.5 cfs to be collected, thereby requiring 12 wells and three additional wells to allow for operation and maintenance. Their total depth would be approximately 50 feet. Further optimizing of the number and spacing of wells would be left for future planning investigations. All facilities in the wash would be protected from floods or located outside of the flood zone. Late summer thunderstorms are common and flood flows in Hanksville Salt Wash were estimated to be; 100 year - 18,000 cfs, 50 year - 14,000, 25 year - 11,000. The collection location was selected considering natural constric- tions confining the collection area, ease of access, and minimizing disturbance to the wash. The site, shown on Figure 2, is a narrow point in the canyon cut by the wash. Access is by existing roads and minor additional road construction. Disturbance is minimized by using existing roads and dewatering only the lower section of the wash. • Monitoring wells would be installed down gradient of the collection site to monitor salinity reduction. Surface water sampling above and below the wash on Muddy Creek would also support this monitoring effort. 2 Saline water would be pumped directly from the collection wells through- 2,900 feet of buried PVC pipeline to the injection well facili- ties, .Inline valves and other controls were included for flow control and system operation, maintenance, and control. Diiposal would be accomplished by deep-well injecting the saline water into a hydraulically isolated geologic formation. The major fac- tor in deep-well injection is having adequate reservoir capacity. The Coconino Sandstone lies at approximately 3,700 feet in depth and is about 1,000 feet thick. The sandstone permeability appears consistently higher ranging from 200 to 650 and has a porosity range of 15 to 25 per- cent. They have low permeabilities and are composed of mudstone, silt- stone, sandstone, and some limestone. The lower confining zone is t -e Hermosa Group and Molas Formation, which is a competent bed of limestone with shale, siltstone, and sandstone. Based on these conservative assumptions, the entire 2.5 cfs can be injected into one well while main- taining acceptable injection pressures over a 50-year operation period. In summary, because of the shallower depth requiring less drilling and injection pressures plus the need for only 1 well, the Coconino Sand- stone was selected as the injection zone. Surface facilities required along with the injection well consist of holding tanks, a sand filtration system, chemical addition equipment, injection pumps, guard filters, and instrumentation. Backwash from the filters would contain sediment from the alluvial wells. This backwash would be contained in an on-site evaporation pond. No hazardous ele- ments were found in the saline water. To handle the corrosive fluids all flow lines and vessels would be constructed of non-metallic materials such as PVC and fiberglass. Linings such as rubber, teflon, and coal-tar epoxy would be used if non- metalic materials were unavailable. Existing roads would be maintained and 6 miles of existing roads would be reconstructed to provide all weather use. A maximum of 20 acres of land would be required for all plan facil- ities, not including existing roads. All proposed land is owned by the Federal Government and administered by the BLM. Emery South Salt Wash Collectable water is estimated to have a concentration ranging from 25,000 to 35,000 mg/L of total dissolved solids (TDS) and a continuous subsurface flow ranging from 0.15 to 0.25 cfs. The same collection techniques were considered here as in Hanksville .Salt Wash. Subsurface saline water is suspected to enter directly into Muddy Creek- at the washes mouth as well as in the wash itself. For this reason subsurface wells were selected as the most effective collection 3 method. This factor also established the collection location, along Muddy Creek above and below the mouth of Emery South Salt Wash. It was assumed that 10 wells would be required to collect the 0.18 cfs of esti- mated subsurface inflow. The 10 wells would be outfitted with submer- sible pumps and combined into a common pipeline. All facilities in the wash would be protected from floods or located outside the flood zone. Summer tropical storms are common and flows of the following magnitude were estimates; 100 year - 9000 cfs, 50 year - 7000 cfs, 25 year - 5000 cfs. Monitoring wells would be installed on the wash and within the col- lection well field to monitor the collection effectiveness. Surface water sampling above and below the wash on Muddy Creek is also recom- mended. Saline water would be pumped directly from the collection wells through 12,000 feet of buried PVC pipeline to conveniently located injection well facilities. Disposal of the saline water would be by deep-well injection. The major difference in the washes is the flow rates. The 0.18 cfs in Emery South Salt Wash could be injected into one well either into the Lead- ville Limestone or the Coconino Sandstone. Because the Coconino is shallower and has a more predictable higher permeability, it was chosen as the injection zone. The Coconino Sandstone at this wash lies at approximately 3,400 feet in depth and is about 800 feet thick. Other formation properties are identical to those described in Hanksville Salt Wash including the confining zones. Designs, using factors previously described, show one well would easily handle required flow rates over a 50 year period. Surface facil- ities and the injection well drilling and operation would be identical to those described in detail previously. They would be scaled back in size to reflect the lower flow rate. It was projected that 9 miles of existing secondary roads would be reconstructed to provide all-weather use. A maximum of 10 acres of land would be required for all plan facil- ities, not including existing roads or power1ine alignments.