Appendix A
Background on the Moab Site and Area



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Appendix A Background on the Moab Site and Area

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Background on the Moab Site and Area20 Driving into the city of Moab from Arches National Park, a visitor might not notice the pile of uranium mill tailings that sits just off the highway near the entrance to the Moab Valley. How does one miss a twelve million ton, 130 acre pile that rises nearly one hundred feet above the level of the riverbank? It is not only that the arresting beauty of this area, nestled between Arches National Park and Canyonlands National Park along the Colorado River in eastern Utah, draws a visitor’s attention away from a rather nondescript, albeit large, pile of mining debris. It is also that the pile, for all its mass, is dwarfed by the grand scale of the environs—a mere ankle on the huge but commonplace Poison Spider Mesa that rises nearly a thousand feet above the pile and extends for miles in each direction. The exposed strata on the sides of the mesa overlooking the water display a record of the area in geologic time, written with the insistent and enduring erosive power of the Colorado River. The pile, too, represents a history of the area, on the more diminutive time scale of human generations, illustrating both the fast-paced physical change brought by industrial mining and milling operations, and the shifting priorities and demands of the city and the nation. What is now termed the Moab Site was once the site of the Uranium Reduction Company’s mill, which processed uranium ore from the surrounding area. The United States’ demand for uranium during the Cold War and the discovery of rich uranium deposits near Moab resulted in a classic American story of a boomtown. The mill was sold in 1962 to the Atlas Corporation, which owned the site and sporadically operated the mill until the company declared bankruptcy in 1998. In 1999, a trust was created to fund remediation of the site and PricewaterhouseCoopers was named as the custodian of the trust. In 2000, Congress passed the Floyd D. Spence National Defense Authorization Act for Fiscal Year 2001 (Public Law 106-398, hereafter referred to as the Act), which transferred ownership of and responsibility for the site to the U.S. Department of Energy (DOE). The Moab Site thus joined over 100 other sites that DOE must remediate as part of the legacy of the Cold War. The Act also required DOE to ask the National Academy of Sciences (NAS) to review DOE's plan for remediation of the Moab Site. The Act specifically directs DOE to ask the NAS to provide technical advice and recommendations to assist DOE in objectively evaluating costs, benefits, and risks associated with remediation alternatives for the Moab Site, including removal or treatment of radioactive or other hazardous materials at the site, ground water restoration, and long-term management of residual contaminants. The National Research Council, the chief operating arm of the NAS and the National Academy of Engineering, charged its Committee on Long-Term Institutional Management of DOE Legacy Waste Sites: Phase 2 with carrying out those tasks. Historical Background on the Moab Area21 Native Americans belonging to Ute tribes lived in what is now called the Moab Valley until 1878 when, after a failed attempt in 1855, a Mormon settlement took hold. Before these settlements, the fifteen-mile long, three-mile wide valley was part of the northern route of the Old Spanish Trail—connecting Los Angeles and Santa Fe—locally following the path of what is now U.S. Highway 191 across the Colorado River (see Figure 2). The area’s role as a provider of raw material for nuclear science began when it was discovered that carnotite, a red and yellow mineral found on the Colorado Plateau, contains radium. Radium mines in what are now Grand 20   Most of the history of the Moab area is taken from various articles in the Utah History Encyclopedia, with additional details taken from the Reference [U.S. NRC 1999], in this report. 21   See Figure 1 for a current-day map of the region, Figure 2 for a map of the Moab Site and its vicinity, and Figure 3 for an aerial photograph of the area with landmarks.

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and San Juan counties provided ore to Marie and Pierre Curie, who earlier were the first to isolate the element. Radium was also provided for ill-conceived radium “cures” and for luminous paint used for clocks and watches. For the first half of the twentieth century, mining was a small but significant part of the Moab economy, which was dominated by ranching, farming, and fruit growing. This changed with the dawning of the Atomic Age. After World War II, the U.S. Atomic Energy Commission (AEC) announced an effort to obtain uranium from within the United States. The AEC constructed federally owned mills, identified promising locations for prospectors, paid bonuses for new lodes of high-grade ore, guaranteed minimum prices, and helped with haulage. The uranium boom truly took hold in 1952 after Charlie Steen, a geologist from Texas, found high-grade ore in the Big Indian Wash of Lisbon Valley, southeast of Moab. Steen had been searching for two years in areas that others thought were barren of ore. In fact, he found some of the richest ore in the United States. Steen formed the Uranium Reduction Company and opened the nation’s second largest uranium processing mill in 1956, the first designed to process the uranitite ore he found. The population of Moab soared from 1,275 in 1950 to 4,682 in 1960. In 1962 the mill was sold to the Atlas Corporation, in the same year that the AEC announced it had ample amounts of uranium and the buying program would be phased out over eight years. In 1970, uranium production in the area virtually stopped and, except for a small revival based on perceived demand for nuclear power plants in the mid-1970s, it has never really revived. Other booms and busts have hit the area. Oil fields operated near Moab around the same time as the uranium boom. In 1963, the Texas Gulf Sulphur Company opened a potash mining plant in the area, and despite huge expansions and contractions in the local operations, potash is still produced by Moab Salt, Inc. near Moab. Today, tourism is the mainstay of the local economy, and the population of Moab, which is also now the county seat for Grand County, is once again rising. Tourists from around the world are attracted to the area for its natural beauty, exemplified by (but not limited to) adjacent Arches National Park, nearby Canyonlands National Park, and the magnificent gorges of the Colorado River and their grand portals into Moab Valley. The land now derives an economic value from its undisturbed state rather than from its mineral and fossil resources. The Geological Setting at the Moab Site22 The Moab Site is physiographically located in the Colorado Plateau Province, and geologically located in the fold-and-fault belt of the Pennsylvanian Paradox basin. The Colorado River flows along the southeast side of the Moab Site. Geologic features of the area were influenced by Middle Pennsylvanian to Late Triassic salt tectonics, Middle Pennsylvanian to Late Cretaceous sedimentation, Tertiary folding and faulting, and Quaternary erosion and salt dissolution. With the uplift of the Colorado Plateau, the Colorado River eroded the sedimentary formations and formed deep canyons, slopes, and cliffs. The formations formed either cliffs or slopes according to their erosional resistance. After erosion cut down deep enough, ground water reached the upper parts of the underlying evaporite deposits and dissolved salt. The ensuing collapse created graben-valleys, such as the Moab Valley, that overlie the salt deposits. The Moab Site is at the northwest end of the Moab Valley. Consolidated sedimentary rocks exposed in the area range in age from Middle Pennsylvanian to Late Cretaceous. Unconsolidated deposits of sand, silt, gravel, and clay, which are products of the current erosional regime, overlie the bedrock formations in places. Thickness and distribution of the geologic units vary considerably in the area. 22   With the exception of the streamflow data, this section is extracted from the Draft Preliminary Plan for Remediation [DOE 2001]. Some portions have been omitted, but essentially all of this section is quoted or adapted from that document.

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The Moab Site is bordered on the north and west sides by bedrock units, and by the Colorado River on the southeast side. The ephemeral Moab Wash enters the site at the northwest corner and drains through the site into the Colorado River. The site is directly underlain by Quaternary alluvial deposits, which in turn overlie various bedrock units at depth depending on the structural configuration beneath the site. Two large faults are likely present beneath the site, including the northeast-dipping normal Moab fault and the southeast-dipping "arcuate" fault. The arcuate fault defines the northwest extent of the Moab salt valley [SMI 2001]. The Colorado River traverses the valley roughly north to south, connecting two bedrock portals. The nearest gauging station for assessing stream flow is upstream near Cisco, Utah. Figure 4 exhibits the entire data record for annual peak stream flow at the Cisco station. Physical Description of the Moab Site and the Pile The site is irregularly shaped and encompasses approximately 400 acres. A 130-acre uranium mill tailings pile, about 0.5 mile in diameter and averaging about 94 feet (ft) in height above the surface of the Colorado River terrace, is located on the site about 750 ft west of the Colorado River. The Moab Site is bordered on the north and southwest by steep sandstone cliffs. The Colorado River forms the southeastern boundary of the site. U.S. Highway 191 parallels the northern site boundary, and State Highway 279 parallels the southwestern boundary. The entrance to Arches National Park is located less than one mile northwest of the site across U.S. Highway 191; Canyonlands National Park is about 12 miles to the southwest. The Union Pacific Railroad traverses a small section of the site just west of State Highway 279, then enters a tunnel and emerges several miles to the southwest. Moab Wash runs northwest to southeast through the center of the site and joins with the Colorado River. The wash is an ephemeral stream that flows only after precipitation or during snowmelt. Figure 2 shows major site features. The map in Figure 2 was completed in 1983; the majority of on-site buildings have since been demolished and the on-site tailings were consolidated. However, contamination is still present in many areas of the site. The pile consists of an outer compact embankment of coarse tailings, an inner impoundment of both coarse and fine tailings, and an interim cover of soils taken from the site outside the pile area. The pile has five embankments, or terraces, that were raised to their present elevation of 4,076 ft above mean sea level after a 1979 license renewal. Debris from dismantling the mill buildings and associated structures has been placed in an area at the southern toe of the pile and covered with contaminated soils and fill [USNRC 1999]. A geotechnical, geochemical, and hydrologic investigation of the tailings impoundment was conducted by Steffen Robertson and Kristen [SRK 2000] on behalf of the site Trustee. The results of the investigation indicated that the center of the tailings pile remains saturated. In order to dewater and consolidate the pile, vertical band drains, also called wicks, were installed to within approximately 10 feet of the bottom of the tailings on roughly 3 meter centers over most of the impoundment surface. The surface of the tailings was surcharged with impacted surface soils excavated from the mill site and materials from the regrading of the impoundment side slopes. This surcharging caused increased pore water pressure in the tailings that allows tailings water to flow up the band drains to the surface of the tailings for subsequent evaporation [SMI 2001]. Less surcharge was placed on the tailings than originally planned, resulting in slower consolidation rates and less water being brought to the surface of the impoundment than anticipated. To date, no as-built survey of the existing tailings surface configuration is available. Therefore, it is not known how much surcharging was placed on the tailings or how much water has been brought to the surface [SMI 2001]. No accurate estimate of the amount of water brought to the surface by the band drains has been made. The tailings water is ponded on the

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surface of the impoundment and is in communication with the band drains, decreasing the effectiveness of the band drains for dewatering [SMI 2001]. Dewatering continues today, though at a slower rate than previously.

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Figure 1. Current-day map locating Moab in the region (from [DOE 2001]).

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Figure 2. Current-day map showing the Moab Site and its vicinity (from [DOE 2001]).

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Figure 3. Oblique aerial photograph (courtesy of DOE). Markings in white were added by the committee. Directions, distances, and boundaries are approximate, and the distance scale corresponds roughly to the location of the pile in the picture.

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Figure 4. Annual peak streamflow for the Colorado River near Cisco, Utah [USGS 2002].