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Programmatic Environmental Impact Statement
For The This section describes the environment that could be affected by implementing any of the alternatives described in Section 2.0. Section 4.0 analyzes the potential impacts of implementing these alternatives. Section 3.1 describes the resources that may be affected during the Ground Water Project; this information was derived from NEPA documents and other reports generated during the Surface Project. Section 3.2 describes the UMTRA Project sites. Site-specific NEPA documents that would tier off this PEIS would provide additional details about the affected environment. The UMTRA Project processing sites were active for varying lengths of time from the 1940s into the 1970s. These sites, the surrounding areas, and the underlying ground water comprise the affected environment for this PEIS. Land contaminated with uranium mill tailings and other hazardous constituents ranged from 21 ac (8 ha) at the Spook, Wyoming, site to 612 ac (248 ha) at the Ambrosia Lake, New Mexico, site (Table 3.1). In total, about 3900 ac (1600 ha) of land were contaminated at the sites. The amount of contaminated materials ranged from approximately 85,000 cubic yards (yd3) (65,000 cubic meters [m3]) at the North Continent Slick Rock, Colorado, site to 5,764,000 yd3 (4,407,000 m3) at the Falls City, Texas, site. The total amount of contaminated material at the sites is approximately 39,000,000 yd3 (30,000,000 m3). The stabilization of the surface contamination at the sites was almost evenly divided between on-site and off-site disposal (Table 3.1). Most sites that had or will have uranium tailings transported off the site are either in urban settings or in river floodplains. Surface remediation of the sites has been in progress since the mid-1980s. Canonsburg, Pennsylvania, the first site to undergo remediation, was completed in December 1985 (Table 3.1). Surface remediation is completed at 18 sites, is under way at 4 sites, and is in the planning stage at 2 more sites. The Canonsburg, Shiprock, and Salt Lake City disposal cell designs were based on EPA standards that were remanded, in part, in 1983. The EPA has determined, based on information from the DOE, that modifications of these disposal cells are not warranted; the final determination will be made by DOE with the concurrence of the NRC (60 FR 2854). This section summarizes the environmental resources at or
near the processing sites. In general, "near" refers
to a location where the resource has the potential to be affected
by site-related contamination or remedial actio
Table 3.1 UMTRA Project surface remedial action status Estimated amount of contaminated watera
aFrom TAC, 1995. The human environment at each UMTRA Project site includes everyone who lives in or near the direction of the contaminated ground water plume. The Surface Project addresses human exposure to the tailings, and the Ground Water Project addresses human exposure to ground water contamination. All UMTRA Project sites except the Canonsburg, Pennsylvania, site and the associated Burrell vicinity property are in the western United States, generally in arid or semiarid environments. Fifteen sites are in dry climates and receive less than 12 inches (30 centimeters [cm]) of precipitation annually; six sites receive 12 to 20 inches (30 to 50 cm) annually; and three sites receive more than 20 inches (50 cm) annually (Table 3.2). Twenty-two sites are near surface water bodies, including major rivers such as the Colorado, Dolores, San Juan, and Yampa Rivers (Table 3.2). Perennial streams and ponds occur near a few sites. Ephemeral and intermittent washes and arroyos occur near many of the sites. Ground water contamination in varying degrees has been observed at all but one of the sites. Lowman, Idaho, is the only site where ground water contamination does not exist. Milling at the Mexican Hat, Utah, and the Ambrosia Lake, New Mexico, sites created areas saturated with contaminated ground water in geological formations that previously did not contain ground water; however, contamination of naturally occurring ground water has not been observed. Seepage of contaminated water has affected the naturally occurring underlying aquifers at the remaining 21 sites. Some of the more common hazardous constituents that exceed maximum concentration limits at UMTRA sites include uranium, molybdenum, and selenium. Table 3.3 shows constituents that have exceeded maximum concentration limits at least twice. This summary includes only the constituents for which EPA has established an UMTRA Project maximum concentration limit; other constituents associated with uranium processing exceed background levels at some sites and may be detrimental to human health and the environment. Ground Water Project documents that will address all site-specific constituents of concern include the baseline risk assessments and site observational work plans. The estimated total amount of contaminated ground water at
the UMTRA sites is 10,436,000,000 gal (39,318,000 m3) (Table
3.1). The volume of contaminated ground water ranges from
none at the Lowman site to approximately 1,900,000,000 gal
(7,000,000 m3) at the Gunnison site. At sites with contaminated
ground water, the percent of off-site contamination ranged
from none at the Belfield, Canonsburg, and Slick Rock Union
Carbide sites to 98 percent at the Gunnison site.
Table 3.2 Resources at UMTRA Project processing sites Site Characteristics
aFrom TAC, 1995.
Hazardous constituenta
aSome of the constituents that exceed the maximum concentration limits may be naturally occurring and not from uranium milling activities. For regulatory compliance purposes, the mean exceedance would be used with all alternatives except no action. bThe Belfield and Bowman, North Dakota, processing sites are not shown. They will not be remediated by DOE since the state has declined to provide their statutorily required cost-sharing to remediate the sites. cAreas of saturation of contaminated ground water
were created in geological formations beneath the site that
previously did not contain ground water. 3.1.1.5 Ecological resources and wetlands Most UMTRA Project sites are in areas dominated by desert shrub or desert grassland plants. Riparian plant communities along rivers, streams, washes, and arroyos occur at or near most sites. Threatened, endangered, and other species of concern occur at or near 14 sites, including several species of plants, endangered fish, and birds such as the bald eagle and peregrine falcon. Wetlands have been identified at or near 18 sites (Table 3.2). Wetlands at 10 of these sites have been or will be affected by the Surface Project; these impacts have been or will be mitigated. Land use in and around UMTRA Project sites in urban areas ranges from industrial and commercial to residential and public. In rural settings, land use includes farming and ranching. Some rural lands are managed by the Bureau of Land Management. 3.1.1.7 Cultural/traditional resources Areas at or near 11 of the UMTRA Project sites contain cultural
resources (Table 3.2). These include
archaic Native American lithic scatters, Anasazi ruins, and
limited property from historical industrial and mining activities.
In addition, water resources, including ground water and seeps,
have traditional value to Native Americans. Many UMTRA Project
sites fall within or near boundaries of tribal lands. Cultural
resource investigations conducted primarily for the UMTRA
Surface Project have identified cultural resources at two
sites associated with tribal lands (Monument Valley, Arizona,
and Riverton, Wyoming). Other resources of cultural interest
to Native Americans may occur on other sites located on tribal
lands (such as Tuba City, Arizona; Shiprock, New Mexico; and
Mexican Hat, Utah) or lands associated with historic Indian
occupation. More detailed information on cultural resources
would be included in site-specific Ground Water Project environmental
documents. Additional cultural resource investigations would
be conducted, if required, prior to any site-disturbing activities
associated with ground water compliance actions. Existing transportation networks at and near the processing sites accommodate local uses. All sites are accessible to vehicles. Remote areas that may be affected by the Ground Water Project may not be readily accessible to vehicular traffic. 3.1.1.9 Social and economic resources Of the designated UMTRA Project sites, 3 are in cities, 7 are at the edge of towns or cities, and 14 are in rural areas or remote settings (Table 3.2); 5 sites are on Indian lands representing four Native American tribes. Typically, the population characteristics and economies of the more rural, sparsely populated site areas are related primarily to agricultural activities such as ranching, grazing, and dryland farming, or to mining and energy exploration and development. Two sites in forested areas also are involved in forest-related uses such as logging. Suburban or urban sites have more diverse population and economic bases that include light industrial and commercial activities; residential areas also are located near these sites. Site ownership includes private, tribal, and public lands managed by the U.S. Forest Service and the Bureau of Land Management. 3.1.1.10 Environmental justice Achieving environmental justice is part of DOE's mission. DOE identifies and addresses the disproportionately high and adverse human health or environmental effects of its programs, policies, and activities on minority populations and low-income populations. For the UMTRA Ground Water Project, the potential exists for disproportionately high and adverse effects on five sites that are on or partially on tribal lands. The sites on tribal lands are the Tuba City and Monument Valley, Arizona, sites; Shiprock, New Mexico, site; and the Mexican Hat, Utah, site. The Riverton, Wyoming, site is partially on tribal lands. This PEIS addresses the potential programmatic effects of the ground water compliance strategies and alternatives. Site-specific NEPA documentation would further analyze potential effects. The policy issues identified below define the fiscal and regulatory context of the UMTRA Ground Water Project. These issues may affect or be affected by implementing the proposed action or alternatives. The UMTRA Project participates in the federal budget development process by requesting congressional appropriations to meet UMTRA Project requirements. Since the inception of the UMTRA Project, the DOE has been required to develop annual federal funding requests. Because Congress cannot appropriate funds without a fully justifiable estimate, assumptions concerning site-specific compliance strategies must be made so as to derive cost estimates that will support budget submittals. These assumptions are for budgetary purposes only and in no way indicate that site-specific ground water compliance decisions have been made prior to completion of the PEIS or site-specific environmental documents. With input from UMTRA Project contractors, budget development is managed by the DOE in accordance with DOE orders and guidance. Budget development includes preparing a "bottom-up" budget for the annual field budget submittal, developing and controlling contingencies, and examining and reestimating budget requirements through Project completion. The budget development process ensures that the DOE adequately plans for its fiscal year requirements and conducts and assesses the long-range planning needed to complete the Project. To accomplish these objectives, a total Project (or life-cycle) budget is developed each year with input from all Project participants/contractors. Although congressional appropriations are for only 1 year, the estimated budget for the entire UMTRA Project must be presented to DOE Headquarters, the Office of Management and Budget, and finally, to Congress to identify future budget requirements. The current Ground Water Project cost projection is $497 million with a completion date of 2014; these estimates are based on the fiscal year 1997 field budget. At times, the field budget submitted by the UMTRA Project is not fully funded. This can be the result of budget changes as program priorities are balanced at the federal level. Reductions in the requested funds can and often do affect the Project schedule, such as pushing work further into the future. These schedule slips have the potential to increase the overall Project cost due to escalation; schedule slips that extend work beyond the currently identified completion date can add additional Project management costs. Section 2.10 describes the basis for estimates of the ground water compliance strategies analyzed in Section 4.0. Section 1.4, Regulatory Compliance, describes the EPA, NRC, DOE, Executive Order, and tribal law requirements with which the UMTRA Project must comply. Numerous documents, including environmental impact statements, environmental assessments, and remedial action plans, have been published or are being prepared that describe the existing site environment and surface remediation construction conditions at the UMTRA Project sites. These documents form the basis for the site descriptions presented in this document. The descriptions focus on factors most relevant to ground water remediation, including existing ground water data, local population and private well information, and other sensitive resources (for example, surface water bodies and wetlands) that may be affected by contaminated ground water. Descriptions of ground water quality were based on the 1992 Annual Environmental Monitoring Report (DOE, 1993c) for sites where remedial action is under way or complete. Other ground water quality information was obtained from the latest site-specific surface remedial action document. The discussion of ground water is limited to ground water in the uppermost aquifer, background ground water quality, and water-bearing units and aquifers that have been contaminated by milling activities. At some sites, contaminated ground water has migrated downward into previously unsaturated geologic formations above the natural water table. These formations contain small zones of saturation that resulted from milling activities. At most of the remaining sites, milling-related contaminants have entered only the shallow aquifers beneath the sites. Deeper aquifers are discussed only if they represent the uppermost aquifer or have been contaminated. Background ground water quality at some UMTRA Project sites is naturally poor due to uranium ore bodies and past mining activities, and natural highly mineralized aquifer matrix material. 3.2.1 Monument Valley, Arizona The Monument Valley UMTRA Project site is in Apache County, Arizona, in an isolated setting along Cane Valley Wash on tribal land. The county per capita income is $5399; the population is predominantly Native American (DOC, 1990). The site is approximately 13 miles (mi) (21 kilometers [km]) east of the scenic Monument Valley tribal park. Comb Ridge, the most prominent topographic feature, is east of the site. The Monument Valley tailings site consisted of two tailings piles, windblown-contaminated soil, and piles of debris. The total amount of contaminated material at the site was 942,000 yd3 (720,000 m3) on 83 ac (34 ha). All the contaminated material has been moved to the Mexican Hat, Utah, disposal cell 17 road mi (27 km) to the north, and surface remedial action was completed in May 1994. The Monument Valley site is in a sparsely populated area. The nearest town is Dennehotso, about 5 mi (8 km) south, in Apache County; the county population is 61,591 (DOC, 1990). The climate is arid, with an average annual precipitation of 6 inches (15 cm) and an average annual snowfall of 3.3 inches (8.4 cm) (DOE, 1993d). Six cultural resource sites have been identified near the site and are eligible for inclusion on the National Register of Historic Places (DOE, 1989a). The region is characterized by a desert shrub habitat with scattered junipers occurring on higher terrain and rocky areas. There are no known threatened or endangered species at or near the site (DOE, 1989a). Surface water features at the Monument Valley site consist of Cane Valley Wash and several small ephemeral drainages. These drainages flow northeast into Cane Valley Wash (DOE, 1989a). A series of spring-fed wetlands and ponds occur along Cane Valley Wash, northeast of the tailings site area and extending at least 3 mi (4.8 km) north. The Frog Pond is the surface water body closest to the site (2000 ft [600 m] to the east); this pond has not been contaminated. Downstream from the site (2.2 mi [3.5 km]), are additional surface water bodies and wetlands that have not been affected by site-related contaminated ground water. Ground water occurs in the alluvium and dune sand underneath the Monument Valley site and in the underlying bedrock formations. The depth to ground water in the alluvium is from a few feet in Cane Valley Wash to slightly more than 10 ft (3 m) under the site. This ground water is recharged by occasional infiltration from precipitation and upward leakage from the underlying aquifers. The ground water in the alluvium flows north at an estimated velocity range of 90 to 200 ft (27 to 61 m) per year. Below the alluvial aquifer, ground water occurs in the Shinarump Conglomerate and the confined De Chelly Sandstone aquifer. Ground water flows north at an estimated rate of 6 to 100 ft (2 to 30 m) per year in the Shinarump Conglomerate and 150 ft (46 m) per year in the De Chelly Sandstone. Background ground water quality in these three aquifers shows no statistical evidence that any hazardous constituent exceeds maximum concentration limits. Contamination in the alluvial ground water beneath the site has exceeded the maximum concentration limits for net gross alpha, nitrate, radium-226 and -228, and uranium twice since 1990. A nitrate plume approximately 3000 ft (900 m) extends north of the site. The estimated amount of contaminated ground water at the Monument Valley site is 1.2 billion gal (4.5 million m3). Concentrations of nitrate, net gross alpha, and radium-226 and -228 have exceeded the maximum concentration limits in the Shinarump at least twice since 1990. The maximum concentration limits for gross alpha and uranium have been exceeded in the De Chelly at least twice since 1995. Two domestic wells are completed in the alluvial aquifer just south and upgradient of the site. Other residents near the site use artesian ground water from the De Chelly Sandstone that flows from monitor wells or former production wells. Ground water analyses from all these sources show no sign of contamination (DOE, 1993d). The Tuba City UMTRA Project site is in Coconino County, Arizona, 6 air mi (10 km) east of Tuba City (population 7300) (DOC, 1990) on tribal land. The county per capita income is $8683; the population in the vicinity is predominantly Native American (DOC, 1990). The site is on the Kaibito Plateau in the desert shrub vegetation zone. The surrounding terrain is dominated by dissected sandstone formations, mesas, and alluvial terraces. The tailings, windblown and waterborne deposits, demolished mill building, and other contaminated material, which totaled 785,000 yd3 (600,000 m3) on 327 ac (132 ha), were stabilized on the site in a 50-ac (20-ha) disposal cell (DOE, 1989b). Surface remediation was completed in May 1990. The site is arid, with an average annual precipitation of 6 inches (15 cm) and an average annual snowfall of 4 inches (10 cm) (DOE, 1986a). There are no known cultural resources or threatened or endangered species at the site (DOE, 1986a). The site is approximately 7000 ft (2100 m) northwest of Moenkopi Wash, an intermittent stream that joins the Little Colorado River to the southwest. No other watercourses exist in the vicinity of the site. A natural spring and seeps appear along the base of an escarpment, approximately 6000 ft (1800 m) east-southeast of the site. The largest of these is used to water livestock. The other seeps have very little flow and are evident most often by the occurrence of riparian plant species and damp areas on the cliff face. Analysis of water and saturated soil samples from one seep south of the site indicates these seeps are not contaminated. The flow in Moenkopi Wash varies from periods of no flow to flows of more than 14,500 cubic feet per second (ft3/s) (411,000 L per second) (DOE, 1986a). Surface water and sediment sample analysis from Moenkopi Wash indicates this wash is not affected by contaminants from the Tuba City site (DOE, 1986a). The uppermost aquifer at the Tuba City site is in the Navajo Sandstone. This formation is up to 430 ft (130 m) thick in the site area. The water table ranges from 20 to 150 ft (6 to 50 m) deep. Ground water in this aquifer flows southeast toward Moenkopi Wash at an estimated average velocity of 2 to 100 ft (0.6 to 30 m) per year. Ground water beneath the site is contaminated, and levels of molybdenum, nitrate, selenium, uranium, and net gross alpha and radium-226 and -228 activity have exceeded the maximum concentration limits at least twice since 1990. The plume of contamination extends approximately 1500 ft (460 m) downgradient from the site. The estimated amount of contaminated ground water at the Tuba City site is 780 million gal (3 million m3). Ground water is not withdrawn from the plume area. Water is taken from springs near Moenkopi Wash and from the wash itself, downgradient of the site. These use areas are all greater than 1 mi (1.6 km) from the Tuba City site (DOE, 1989b). The Durango processing site is in La Plata County, Colorado, just southwest of the city of Durango. The site is on the west side of the Animas River, extending from the floodplain to the base of Smelter Mountain. The site consisted of two areas: the tailings piles in the milling area and the raffinate pond area about 0.5 mi (0.8 km) to the south. Approximately 2,534,000 yd3 (1,937,000 m3) of contaminated material were removed from the 127-ac (51-ha) site and associated vicinity properties (DOE, 1985a). The contaminated material was transported to the Bodo Canyon disposal site, approximately 3.5 mi (5.6 km) from the processing site. Surface remedial action was completed at the Durango processing site in May 1990. The Durango site was revegetated after the completion of remedial action and contains a healthy stand of vegetation. Surface water bodies include the Animas River and Lightner Creek, both of which border the site. Surface water and sediment samples indicate contaminated ground water from the site has not contaminated these water bodies or their sediments. Riparian vegetation along the Animas River consists of cottonwoods and box elders. Threatened or endangered species are known to exist at or near the site (DOE, 1985a). These species include the bald eagle, which winters along the river, and the peregrine falcon, which nests about 1 m (1.6 km) from the site. The Durango area has a semiarid climate, with an average annual precipitation of 19 inches (48 cm). The processing site is near the city of Durango, with an estimated 1990 population of 12,430. La Plata County had an estimated 1990 population of 32,284 (DOC, 1990). The nearest year-round resident is immediately west of the site. The processing site contains no known cultural resources (DOE, 1985a). The Durango processing site is underlain by approximately 1760 ft (520 m) of Mancos Shale bedrock. The Mancos Shale bedrock is truncated along the Smelter Mountain fault at the south end of the terrace supporting the site. The bedrock is overlain by approximately 5 to 20 ft (1 to 6 m) of alluvium and man-made fill. Ground water moves through the alluvium (uppermost aquifer) as a thin (less than 3-ft [1-m]-thick) layer on top of the almost impermeable shale. The depth to ground water ranges from less than 3 ft (1 m) along the river to more than 40 ft (12 m) near the mountain. The ground water moves toward Lightner Creek and the Animas River, but the irregular surface of the bedrock makes it impractical to calculate a hydraulic gradient or the rate of ground water movement. The former raffinate pond area is underlain by alluvium similar to the mill and tailings piles area and overlies relatively permeable sandstone. Ground water moves toward the Animas River through both the alluvium and the bedrock. The rate of ground water movement is estimated to be 800 ft (240 m) per year in the alluvium and 75 ft (22 m) per year in the sandstone. The amount of discharge to the Animas River is probably minimal compared to flow in the river. The minimum 7-day low flow recorded in the Animas River was 100 ft3/s (3 m3 per second) in December 1917. Analysis of background water quality of the alluvial aquifer indicates that concentrations of cadmium, chromium, molybdenum, net gross alpha, and selenium have exceeded the maximum concentration limits several times. Seven hazardous constituents have exceeded the EPA maximum concentration limits in the alluvial aquifer beneath both areas of the site at least twice since 1990: cadmium, lead, molybdenum, net gross alpha, radium-226 and -228, selenium, and uranium. The estimated amount of contaminated ground water at the Durango site is 100 million gal (0.38 million m3). Water beneath the former processing site is not used for human consumption, and there is no evidence of elevated hazardous constituents in the Animas River as a result of alluvial aquifer discharge into the river. The city of Durango and properties near the site are served by a municipal water supply system. Water for this system is withdrawn from the Animas River upstream of the Durango UMTRA Project site. In addition, the water intake for a planned irrigation project will be in the river in the southern portion of the Durango site. 3.2.4 Grand Junction, Colorado The Grand Junction site is on state-owned land in the city of Grand Junction, in Mesa County, Colorado, along the north side of the Colorado River. Approximately 4,655,000 yd3 (3,559,000 m3) of contaminated material were on 114 ac (46 ha) at the processing site (Sanders, 1993). During surface remedial action, all the contaminated material was moved to the Cheney disposal cell, 18 mi (29 km) southeast of the Grand Junction site (DOE, 1986b). The transportation of this material began in 1991; remedial action was completed in August 1994. The population of Grand Junction is 29,034 (DOC, 1990). There are no cultural or historic resources at the Grand Junction site (DOE, 1986b). The site was constructed in the floodplain of the Colorado River, and a series of small islands and river side channels occurs between the site and the river. This area supports a dense growth of riparian vegetation and a diverse wildlife species. Other than 8 ac (3 ha) that were cleaned up during surface remediation, there is little or no site-related contamination in the area (based on analysis of surface water and sediment samples). The Grand Junction site is arid, with an average annual precipitation of 8 inches (20 cm). Snowfall averages 27 inches (69 cm) annually (DOE, 1986b). Threatened or endangered species have been identified near the site (DOE, 1986b). These include the bald eagle, which winters along the river, and the Colorado squawfish, which may occur in the side channels of the Colorado River next to the site. The Grand Junction processing site is underlain by Colorado River alluvium (uppermost aquifer) that ranges in saturated thickness from less than 10 ft (3 m) to more than 20 ft (6 m). Alluvial ground water levels beneath the site vary from 2 to 5 ft (1 to 2 m) annually, with the lowest levels occurring during the fall and winter. Ground water in the alluvial aquifer flows west and southwest, depending on the stage of the Colorado River, and eventually discharges to the river. The estimated ground water velocity is 73 to 1800 ft (22 to 550 m) per year. The uppermost aquifer is underlain by the Mancos Shale, which functions as an aquitard in the area. At this time, there is some uncertainty regarding background water quality at the Grand Junction site. The background water in the alluvial aquifer has high concentrations of salts such as sulfate. Concentrations of molybdenum, selenium, and uranium and activities of net gross alpha exceeded maximum concentration limits in background ground water at least once. Seeping tailings fluids have contaminated ground water in the alluvium beneath the processing site. This contaminated ground water extends west from the site for approximately 2500 ft (760 m). Concentrations of molybdenum and uranium and activities of net gross alpha have exceeded the maximum concentration limits beneath and downgradient from the site at least twice since 1990. The estimated amount of contaminated ground water at the Grand Junction site is 330 million gal (1.3 million m3). The Mancos Shale aquitard prevents contaminated ground water from moving any deeper (DOE, 1991b). The Gunnison processing site is on state-owned land and is adjacent to the city of Gunnison in Gunnison County, Colorado. In 1990 the city of Gunnison had an estimated population of 4636, while Gunnison County had an estimated population of 10,273 (DOC, 1990). The site is on a drainage divide between the Gunnison River and Tomichi Creek in the Gunnison River valley. Approximately 719,000 yd3 (550,000 m3) of contaminated material were on 68 ac (28 ha). The contaminated material was moved to the Gunnison disposal site approximately 6 mi (10 km) from the processing site. Surface remedial action began in May 1992 and was completed in December 1995. The processing site is on the floodplain alluvium between the Gunnison River and Tomichi Creek. The site is about 0.4 mi (0.6 km) east of the Gunnison River and 0.4 mi (0.6 km) west of Tomichi Creek. It is bounded on the west by small storm drainage ditches and on the south and west by irrigation ditches. Surface water and sediment samples have been collected from the Gunnison River and Tomichi Creek upstream and downstream from the processing site and from shallow ponds near the site. No site-related contaminants have adversely affected the surface water and sediments in surface water bodies near the site. An analysis of threatened and endangered species indicates the Gunnison River contains no endangered fish species (DOE, 1992a). Endangered species near the site include the whooping crane, which stops and feeds in the floodplain of Tomichi Creek during migration, and the bald eagle, which occurs along the Gunnison River during the winter. The Gunnison milk vetch, a federal candidate plant species, was growing on the tailings pile. There are no known cultural resources at the site (DOE, 1992a). The site is semiarid, receiving an average annual precipitation of 11 inches (28 cm) and an average annual snowfall of 58 inches (147 cm) (DOE, 1992a). The uppermost aquifer at the site is in the alluvial deposits of the Gunnison River and Tomichi Creek. These floodplain alluvial deposits extend to at least 110 ft (34 m) beneath the processing site. This aquifer is recharged from rain, snowmelt, the Gunnison River, Tomichi Creek, and seasonal recharge from irrigation ditches around the site. Ground water discharges into the Gunnison River and Tomichi Creek. The average depth to ground water beneath the site is 5 ft (2 m). This ground water flows southwest at an average of 270 ft (80 m) per year. Background ground water quality in the alluvial aquifer does not exceed EPA ground water standards. Tailings seepage has contaminated the alluvial ground water beneath the processing site; net gross alpha, radium-226 and -228, and uranium have exceeded the maximum concentration limits at least twice since 1990. The uranium plume extends approximately 7000 ft (2000 m) southwest from the site to the Gunnison River. The estimated amount of contaminated ground water at the Gunnison site is 1.9 billion gal (7 million m3). Downgradient of the site, 311 private wells are completed in the alluvial aquifer. Twenty-two of these private wells are known to contain elevated levels of uranium from the processing site plume. A permanent alternate water supply system was constructed for the residents who have wells in and adjacent to the contaminant plume. The municipal water supply for the city of Gunnison is unaffected by the contamination because it comes from wells in the alluvial aquifer upgradient of the processing site (DOE, 1991c). The Maybell processing site is in Moffat County, Colorado, 25 mi (40 km) west of the city of Craig and 5 mi (8 km) northeast of the unincorporated village of Maybell. Approximately 3,500,000 yd3 (2,700,000 m3) of contaminated material are at the processing site and in the windblown contaminated areas on 214 ac (87 ha). In addition, 1.9 mi (3.0 km) of Johnson Wash and 1.0 mi (1.6 km) of Lay Creek were contaminated by the inadvertent discharge of 200,000 to 400,000 pounds (90,000 to 180,000 kilograms) of tailings and the routine discharge of tailings pond effluent into these streams in the early 1960s. The proposed surface remedial action is to stabilize all contaminated material in place. The Maybell processing site is in a remote area of sagebrush and piñon-juniper habitat. The site is partly on Bureau of Land Management land and partly on private land. The principal land uses are grazing and hunting (for mule deer, pronghorn antelope, and sage grouse). Wetlands occur along Johnson Wash and Lay Creek near the site. Johnson Wash is a dry arroyo that runs near the eastern border of the site. This wash joins Lay Creek about 1 m (1.6 km) south of the site. This creek is a tributary of the Yampa River and the confluence is about 5 mi (8 km) southwest of the site. No site-related contaminated ground water has entered or is expected to enter these bodies of water. The population of Moffat County is 11,357 (DOC, 1990). Although one historic site occurs near the site, it is not considered eligible for inclusion on the National Register of Historic Places (DOE, 1995a). The Maybell site is semiarid. The average annual precipitation is more than 13 inches (33 cm); snowfall averages more than 80 inches (200 cm) annually (DOE, 1995a). Threatened or endangered species that occur near the site along the Yampa River include wintering bald eagles and the Colorado squawfish (DOE, 1995a). The processing site is underlain by the Browns Park Formation. The uppermost aquifer is in the upper sandstone unit of this formation. Ground water within this formation ranges in depth from 35 to 300 ft (11 to 90 m) beneath the site. Ground water flows southwest at an average velocity of approximately 40 ft (12 m) per year. Recharge to the uppermost aquifer is principally from infiltration of precipitation and snowmelt. Ground water from this aquifer discharges into the alluvial aquifer of the Yampa River. Background ground water quality is affected by natural mineralization related to the uranium ore body; selenium and uranium levels exceed the maximum concentration limits. Contaminants from the processing site have entered the aquifer beneath the site but because of advantageous geochemical conditions, the contamination has not passed the site boundary. Contaminants that have exceeded the maximum concentration limits in the tailings pore fluid and the ground water beneath the site at least twice since 1990 are arsenic, cadmium, molybdenum, nitrate, net gross alpha, radium-226 and -228, selenium, and uranium. The estimated amount of contaminated ground water at the Maybell site is 230 million gal (0.87 million m3). The domestic well nearest the site is 3 mi (5 km) to the southwest in the alluvial aquifer of the Yampa River. Contaminants from the processing site likely will not affect this aquifer because favorable geochemical conditions limit downgradient contaminants migration. In addition, the ground water in the uppermost aquifer is unsuitable for drinking due to widespread ambient contamination that is related to naturally occurring uranium mineralization and to mining activities not related to the uranium milling operations. The Naturita processing site is in Montrose County, Colorado, approximately 2 mi (3 km) northwest of the town of Naturita along the San Miguel River. Much of the site is in the floodplain of the river. Between 1977 and 1979, the tailings were moved to a facility 3 mi (5 km) south of the processing site for reprocessing. There are 547,000 yd3 (418,000 m3) of contaminated material on 247 ac (100 ha) at the site. This total includes 194 ac (79 ha) that were contaminated with windblown and waterborne tailings. Tailings washed down the San Miguel River, contaminating approximately 56 ac (23 ha) of the mostly wooded riparian zone along the river. The contaminated material will be moved out of the floodplain to an off-site disposal cell. Surface remedial action began in April 1995 and is scheduled for completion in September 1997. The Naturita processing site is in a sparsely populated area on the south side of the San Miguel River. The population of the town of Naturita is 430 (DOC, 1990). The San Miguel River is the only surface water body in the site area. Surface water samples have shown that site-related contaminated ground water is not adversely affecting the water in the river. Cottonwoods and willows dominate a riparian wetland zone along the river. Junipers and piñon pines dominate the surrounding hillsides. The San Miguel River contains no endangered fish species. The endangered southwestern willow flycatcher may occur at the site (DOE, 1994d). Wintering bald eagles also occur along the river in the processing site area. The site is on private land. The nearest residence is approximately 2000 ft (600 m) north-northwest of the site. The Naturita site is arid, with an estimated average annual precipitation of 9 inches (23 cm). The average annual snowfall is approximately 30 inches (80 cm). Three prehistoric sites near the site are eligible for inclusion on the National Register of Historic Places (DOE, 1994d). Ground water beneath the Naturita site occurs in the alluvial deposits of the San Miguel River floodplain. This aquifer is recharged by the river southeast of the site and discharges into the river northwest of the site. The alluvial aquifer flows approximately parallel to the river at an estimated linear velocity of 22 ft (7 m) per year. Background ground water quality in the alluvium near the processing site did not exceed the EPA maximum concentration limits. Uranium concentrations indicate a contaminant plume in the alluvial ground water extends approximately 1500 ft (460 m) downgradient from the processing site. Other site-related contaminants that have exceeded maximum concentration limits in this aquifer at least twice since 1990 are arsenic, molybdenum, selenium, radium-226 and -228, and net gross alpha. The estimated amount of contaminated ground water at the Naturita site is 100 million gal (0.38 million m3). Ground water in the Salt Wash a |
