4.6 Dry Lake Valley
The Dry Lake Valley site is near the Apex industrial area, several miles northeast of the intersection of U.S. Highway 93 and Interstate 15. The Nevada Power Company has identified 3,600 acres for development of a Solar Enterprise Zone facility. The DOE would enter into a partnership agreement with the solar industry, Nevada stakeholders, and university systems to develop the solar-generating facilities. The area is bounded on the southwest by development in the Apex industrial area and on the southeast by Interstate 15 and the Dry Lake Range, which runs parallel to the highway.
4.6.1 Land Use
Land in Dry Lake Valley is used for a limited number of activities as discussed in the following Land Use Designations section. Also discussed in this section is the infrastructure related to Dry Lake Valley.
4.6.1.1 Public Land Orders and Withdrawals.
This section is not applicable to Dry Lake Valley.
4.6.1.2 Land-Use Designations.
Land use in Dry Lake Valley is limited to three types: industrial, municipal waste disposal, and land-use management by federal agencies. Industrial land use is limited to the Apex area immediately south of the proposed Solar Enterprise Zone facility site. Current industrial tenants at Apex include Kerr-McGee Chemical Corp., Chemstar Inc., and Georgia Pacific Corp. Silver State Disposal operates a waste landfill and waste processing facilities in the southern part of the basin east of Interstate 15.
4.6.1.3 Site-Support Activities.
Site support in or adjacent to the Dry Lake Valley includes a power substation, a power tie, a phase shifter and autotransformer, and transmission lines; a natural gas pipe line; a landfill; and a fiber-optic line (DOE/NV, 1994b). SERVICESServices discussed for Dry Lake Valley include law enforcement and security, fire protection, and health care. Law Enforcement and SecurityDry Lake Valley is not secured or restricted. Law enforcement is provided by the Clark County Sheriff’s Department. Fire ProtectionFire protection for Dry Lake Valley is provided by the U.S. Bureau of Land Management. Health CareFirst aid stations would be located near field activities, if required. UTILITIESAt the Dry Lake Valley site, located adjacent to the alternative Solar Enterprise Zone location, Nevada Power Company owns and operates a 345/230-kV substation, a 345-kV tie with Pacific Corp, a phase shifter, and a 345/230-kV autotransformer. A 230-kV line is also present that delivers power to the internal transmission system of Nevada Power Company. Nevada Power Company is currently constructing two power plants at the Dry Lake Valley site that will provide a total of 144 megaWatts (MW) and has plans for two additional plants that would provide an additional 144 MW. The current transmission capacity could accommodate 305 MW of solar-generated power; however, after the additional power plants are completed, the Dry Lake Valley system will be able to accommodate only 25 MW of additional power derived from alternate sources. This can only be achieved by investing in the construction of a generator bay. Transmission capacity greater than 25 MW would require additional transmission facilities. Up to 140 MW of solar power could be generated with the addition of a 48 km (30 mi) long, 230-kV circuit from the Dry Lake Valley to the Northwest substation, plus additional substation equipment. With either scenario, the total transmission capacity is relatively low because of plans for constructing gas combustion turbines at the site. Should this construction not occur, the transmission capacity would be greater. Four natural gas pipe line s are within 187 km (116 mi) of the Dry Lake Valley: Transwestern Gas, 187 km (116 mi); El Paso Gas, 75 km (109 mi); Southwest Gas, 24 km (15 mi); and Kern River Gas, 2 km (1 mi). Nevada Power Company anticipates tapping the nearby Kern River pipe line to supply the new gas turbines at the site. However, results of studies related to land, water, and electric transmission capacity must be evaluated before determining whether this apparently readily available gas supply can be used. If so, it is assumed that all necessary natural gas infrastructure required for solar support would be in place.
4.6.1.4 Airspace.
Dry Lake Valley is located east of the NAFR Complex underneath the northernportion of the Las Vegas Class B airspace that begins at 2,438 m (8,000 ft) mean sea level. All aircraft operating in this area must be under positive control of Nellis Approach Control (see Section 4.1.1.4 ).
4.6.2 Transportation
Transportation at Dry Lake Valley is discussed with respect to on-site traffic, off-site traffic, transportation of materials and waste, and other transportation.
4.6.2.1 On-Site Traffic.
This section is not applicable to the Dry Lake Valley.
4.6.2.2 Off-Site Traffic.
Interstate 15, a four-lane, divided freeway, is the major regional access to the Dry Lake Valley site. In 1993, Interstate 15 had an average annual daily traffic of 11,550 vehicles and operated at a level of service A. U.S. Highway 93 runs north and south from the intersection of southwest-northeast-trending Interstate 15. Las Vegas, Nevada, is 35 km (22 mi) southwest of this intersection, and Glendale, Nevada, is 42 km (26 mi) northeast of this intersection. At Glendale, State Highway 168 trends northwest for 39 km (24 mi) and connects with U.S. Highway 93.
4.6.2.3 Transportation of Materials and Waste.
Transportation of waste and materials is not expected at the Solar Enterprise Zone facility site. Therefore, this section is not applicable to Dry Lake Valley.
4.6.2.4 Other Transportation.
Air or rail transportation of workers or materials to the Dry Lake Valley has not been proposed; therefore, these facilities have not been examined in detail. The nearest rail line to the Dry Lake Valley site is the Union Pacific line that parallels Interstate 15 just east of the site. No rail spur exists on the Solar Enterprise Zone facility site. Airfield facilities do not exist on the site. The nearest airport is the North Las Vegas Air Terminal. Traffic information in the vicinity of the Dry Lake Valley Solar Enterprise Zone facility location is discussed in Section 4.6.2.2 , Off-Site Traffic.
4.6.3 Socioeconomics
There are no residences in the Dry Lake Valley. Current land use, exclusive of federal land management, is for industrial purposes, such as manufacturing and municipal waste disposal. The valley is located in Clark County, Nevada, and general existing socioeconomic conditions are presented in Section 4.1.3 .
4.6.4 Geology and Soils
The physiography, geology, and soil conditions in Dry Lake Valley are discussed in this section.
4.6.4.1 Physiography.
The Dry Lake Valley is a topographically closed basin comprised of about 414 km2 (160 mi2) (Figure 4-60 ). Elevations within the basin range from about 1,219 m (4,000 ft) on the west in the Arrow Canyon Range, to about 601 m (1,970 ft) at Dry Lake Playa. The Dry Lake Range on the southeast rises to an elevation of only about 1,036 m (3,400 ft). On the south, the Dry Lake Valley is separated from the Las Vegas Valley by a narrow topographic divide. A somewhat broader divide on the north and northeast separates Dry Lake Valley from the California Wash. On the valley floor, the major features are the many washes that drain the bounding upland areas and the playa in the central part of the valley.
4.6.4.2 Geology.
The general geologic conditions and mineral deposits of the Dry Lake Valley have been described by the Nevada Bureau of Mines and Geology (Longwell et al., 1965). The general geology of the valley comprises three major geologic units: alluvium, Tertiary valley-fill deposits, and Paleozoic carbonate rocks. The alluvium occurs over the valley floor and comprises interbedded gravels, sand, silt, and clay. The total thickness of alluvium is about 305 m (1,000 ft). Figure 4-60. Dry Lake Valley and surrounding area The Tertiary valley-fill deposits include the Muddy Creek Formation, which was deposited over a large area of Clark County. These deposits are found in the area between the Dry Lake Valley and the California Wash and probably occur under the entire valley floor area. The Muddy Creek Formation is comprised of a sequence of interbedded fine-grained and coarse-grained sediments, including claystone, siltstone, and minor sandstone. Gypsum is common in the more fine-grained deposits, and a conglomerate is common along the margins of the depositional basin. The thickness of the Muddy Creek Formation in the Dry Lake Valley is not known, but is probably at least several hundred feet in most areas. The Paleozoic rocks of the Arrow Canyon Range and Dry Lake Range comprise a thick sequence of limestone, dolomites, and quartzite. In the Arrow Canyon Range, this sequence includes, in descending order, the Birdspring Formation, Monte Cristo Limestone, Sultan Limestone, Lone Mountain Dolomite, the Ely Springs Dolomite, the Eureka Quartzite, and the Pogonip Group. These rocks outcrop in the mountainous areas and probably underlie the Muddy Creek Formation at depth under the valley floor area. The total thickness of Paleozoic rocks in the area is unknown, but is probably several thousand feet. Two major geologic structures predominate in the Dry Lake Valley; the Arrow Canyon syncline and the Dry Lake Thrust Fault. The Arrow Canyon syncline is a structural trough that is believed to underlie the south-central part of the basin and occurs along the eastern Arrow Canyon Range in the northern part of the basin. On the eastern part of the basin, in the Dry Lake Range, the Ordovician Pogonip Group has been thrust over the uppermost Paleozoic (Kaibab, Toroweap, Coconino, and Birdspring formations). GEOLOGIC RESOURCESPotential mineral resources in the Dry Lake Valley include fluid minerals (oil, gas, and geothermal resources), non-energy leasable minerals (primarily sodium and potassium compounds), salable minerals (common sand, gravel, and rock), and locatable minerals (metallic and nonmetallic mineral deposits). The U.S. Bureau of Land Management (BLM, 1992) has defined the level of potential for development of these mineral types. The potential for geothermal resources is low, and although the oil and gas potential has been categorized by the U.S. Bureau of Land Management as moderate, there are only two areas with oil leases within the valley. One area islocated in the central Arrow Canyon Range and includes about 8 km2 (3 mi2) of Dry Lake and Hidden Valleys. The second area encompasses about 10 km2 (4 mi2) east of the Union Pacific Railroad’s Dry Lake siding. Two oil and gas exploratory wells have been drilled in the Dry Lake Valley (United Petroleum Corporation No. 1 Apex, and Pozil, Johnson, and Krug No. 1 Apex), but no production has been reported from the basin. The U.S. Bureau of Land Management (BLM, 1992) has categorized the sodium and potassium potential of the Dry Lake Valley as low. Much of the area in the vicinity of the Dry Lake playa has a high potential for salable minerals, primarily silica sand and gravel, with the rest of the areas of alluvium classified as having moderate potential. In the consolidated rock areas of the Arrow Canyon and Dry Lake Ranges, the potential for salable minerals is low. The potential for locatable mineral resources is low over much of the valley; only in the Arrow Canyon Range and in portions of the Dry Lake Range is the potential classified as moderate. Although hundreds of mining claims have been filed within the Dry Lake Valley, the historic mining production has been limited to the production of limestone and dolomite. Chemstar, Inc., has been actively mining and processing limestone in the Apex area for more than 40 years. No metallic mineral deposits have been developed in the valley. The Nevada Department of Transportation maintains several material site rights-of-way in the valley.
4.6.4.3 Soils.
The soils in the Dry Lake Valley are typical desert soils (entisols and aridisols). The soils of the area have been categorized into four series (Nevada Power Company, 1975). The Rockland-St. Thomas series occurs on the foothills and mountains with slopes of 15 to 50 percent and includes rock and cobbly loam. These soils are generally well drained and have a moderately rapid permeability. The Colorock-Tonopah series occurs at an elevation of 396 (1,300 ft) to 914 m (3,000 ft) in areas with slopes of 2 to 8 percent. Colorock soils are gravelly to a depth of 0.3 m (1 ft) and have an underlying hardpan. The gravelly material has a moderate permeability but, because of the presence of shallow hardpan, has a low water capacity. The Tonopah soils, comprising sandy loam and gravellyloam, have high permeability and rapid drainage. Bard-Tonopah soils occur in areas of 2 to 8 percent slope between 457 m (1,500 ft) to 914 m (3,000 ft) in elevation. These soils are stony or sandy loams that exhibit moderate permeabilities and low water capacity. Bard soils are gravelly, sandy loams and gravelly sands with a hardpan occurring at a depth of 0.3 to 0.6 m (1 to 2 ft). The permeability of the Bard soils is moderate, and the water capacity is low. The soils in the Dry Lake Valley are susceptible to erosion by wind and water (BLM, 1992). The potential for erosion is generally slight, except where the soils have been disturbed or along the banks of washes. There is also the potential for localized landslides on the steep slopes of the upland areas. The U.S. Bureau of Land Management (BLM, 1992) indicates that the erosion susceptibility of the soils in the Dry Lake Valley is moderate to high in the northern part of the basin and low to moderate in the southern portion of the basin. The erosion condition ranges from slight to moderate.
4.6.5 Hydrology
Discussion of hydrology is divided into surface water and groundwater. Water supply in the vicinity is also discussed.
4.6.5.1 Surface Hydrology.
Surface water resources in the Dry Lake Valley are meager, occurring only as ephemeral flow in the streambeds that drain the upland areas or in temporary ponding of runoff in the playa. There are no gaging stations in the Dry Lake Valley; total runoff has been estimated at 3.7 x 10-1 m 3/yr (300 acre-feet/year) (Scott et al., 1971). Heavy runoff events may result in short-duration flows along reaches of washes in the basin; however, most rainfall probably infiltrates and is transpired by vegetation or evaporated from the soil. Flooding is probably a recurrent problem over most of the valley floor area in the Dry Lake Valley. Runoff estimates made by the Clark County Regional Flood Control District for the Apex area indicate that a rainfall event with a 0.01 recurrence interval will result in shallow (less than 0.3 m [1 ft]) flooding over extensive areas (Nevada Power Company, 1975). Such floods typically occur as flash floods wherein the depth of the water in the alluvial channels can exceed bankful conditions and result in sheet-flow over large areas of the alluvial fans that bound the playa. The Alkali Flat Dry Lake in the Dry Lake Valley is roughly bisected by some of the land that could be used for a Solar Enterprise Zone facility. In this area, more frequent floods of longer duration are to be expected. Ponding in some areas of the dry lake may be present for periods of several months or more.
4.6.5.2 Groundwater.
The Dry Lake Valley is situated within the California Wash Flow System, a subsystem of the regional Colorado River Flow System (Harrill et al., 1988). Groundwater that originates as precipitation over the upland areas of the valley discharges out of the regional flow system near Overton, Nevada, about 29 km (18 mi) to the east, ultimately reaching the Colorado River through a complicated pathway of groundwater and surface water flow including the Muddy River and Lake Mead. Groundwater under the Dry Lake Valley occurs at depths ranging from about 70 m (230 ft) to 87 m (285 ft) (unpublished U.S. Geological Survey data). Groundwater is derived from two sources: recharge over the basin is 5.0 x 105 m 3 per year (400 acre-feet/year), and subsurface inflow on the west from Hidden Valley is 5.0 x 105 m 3 per year (400 acre-feet/year) (Rush, 1968). Groundwater is discharged via subsurface outflow to the California Wash at a rate of about 1.0 x 106 m 3 per year (800 acre-feet/year), according to (Rush, 1968). There are no springs in the Dry Lake Valley. Groundwater is the only available water resource. There are currently only six water supply wells in the Dry Lake Valley. Well yields within the basin are low, ranging from about 76 to 303 L/min (20 to 80 gal/min). According to information on file with the Nevada Division of Water Resources, the committed groundwater resources of 1.0 x 106 m 3/yr (930 acre-feet/year) are more than double the perennial yield of 5.0 x 105 m3/yr (400 acre-feet/year). Current groundwater rights within the basin include4.0 x 105 m³ (308 acre-feet) for mining, 3.8 x 10 5 m³ (308 acre-feet) for commercial use, 2.0 x 10 5 m³ (168 acre-feet) for industrial use, 1.0 x 105 m³ (75 acre-feet) for municipal and quasi-municipal, and 6.3 x 104 m³ (51 acre-feet) for other uses. As of October 1994, there were 16 applications for water rights in the Dry Lake Valley totaling 1.1 x 106 m³/yr (21,155 acre-feet/year). A master plan has been established for the Apex area in southern-most Dry Lake Valley (Clark County, 1990a). A 21,000-acre industrial-use park is planned for the area with three tenants already operating. This master plan indicates that any water required for industrial purposes at the Apex site would have to be imported to the site. Further, the master plan recommends a policy that private wells be limited to low water-use industries that employ conservation measures. According to information on file with the U.S. Geological Survey, the groundwater in the Dry Lake Valley is generally calcium-sodium-sulfate type with a total dissolved solids concentrations ranging from 700 to 1,000 mg/L (700 to 1,000 ppm), exceeding the primary drinking water standard of 500 mg/L (500 ppm). Sulfate concentrations, reported for three wells in the basin, range from 360 to 380 mg/L (360 to 380 ppm), about 40 percent more than the primary drinking water standard of250 mg/L (250 ppm).
4.6.6 Biological Resources
The scientific names of plants and animals mentioned in this section are given in Chapter 2 of Appendix E , Biological Resources. The plant communities in the Dry Lake Valley are typical of those found in deep, sandy soils throughout this part of the Mojave Desert. The visually dominant plants are creosote bush and white bursage. Other common species include range ratany and Nevada ephedra. Areas around the playa are dominated by saltbush. Blackbrush becomes the dominant shrub on the slopes of the Las Vegas Range (Clark County, 1990a). Animal species in the Dry Lake Valley are similar to those described for the Mojave Desert habitats ofthe NTS. Bighorn sheep inhabit the surrounding mountains. The desert tortoise is the only threatened or endangered species in this area. Densities of tortoises are generally low, though some patches with higher densities may occur (Clark County, 1990a). No current candidate plant or animal species are known to occur in the Dry Lake Valley. The U.S. Fish and Wildlife Service published the latest list of candidate plants and animals on February 28, 1996 (61 FR 7596). Prior to this, six species of mammals, two species of birds, two species of reptiles, and four plant species that were identified as potentially occurring at this site were classified as candidates (Clark County, 1990a; 59 FR 219) and were addressed (Table 4-30 ). The updated Notice of Review has removed all of these species from candidate status. Two of these former candidates are designated as State-protected and are likely to occur in the area: the western burrowing owl and the banded gila monster (Clark County, 1990a). The Geyer milkvetch and the golden bear poppy are two plant species that may occur at the site. These plants are designated by the state of Nevada as threatened with extinction and are classified as "fully protected." Geyer milkvetch was found in nearby areas, but has not been found within the site boundary. Three Category 2 candidate plants have been found at this site. A fourth Category 2 plant, Geyer milkvetch, was found in nearby areas, but has not been found within the site boundary.
4.6.7 Air Quality and Climate
This section includes a description of the air quality conditions at the Dry Lake Valley, including climatology, meteorology, and ambient air quality. CLIMATOLOGY AND METEOROLOGYAlthough there are no weather stations in the Dry Lake Valley, National Oceanic and Atmospheric Administration data on the climate of the area are available for stations located in the Valley of Fire, Logandale, and North Las Vegas. In general, the climate of the valley exhibits the low humidity and low annual precipitation characteristics of the climate of Clark County. The warmest month isJuly, when the mean monthly maximum temperature is 40 °C (104 °F), and January is the coolest month with a mean monthly minimum of 0.5 °C (33 °F). The average monthly wind speed ranges from 12 kph (7 mph) in December to 18 kph (11 mph) in April and June. Diurnal variation in wind is common, reflecting the differential heating of the ground. AMBIENT AIR QUALITYThe Dry Lake Valley, although in Clark County, is located outside of the Las Vegas Valley Nonattainment Area (see Section 4.1.7 ). This part of Clark County is designated unclassifiable/attainment for all criteria pollutants. Dry Lake Valley borders the nonattainment area on the north. The closest Class I Prevention of Significant Deterioration area is Grand Canyon National Park, 100 km (63 mi) southeast of the Dry Lake Valley. Because the Dry Lake Valley is largely undeveloped, there are few emission sources in the area. Typical sources include mining and manufacturing operations at the southern end of the basin; on-road and off-road vehicle, railroad, and aircraft traffic; and fugitive dust. Background air quality data for Dry Lake Valley are summarized in Table 4-42 . These background data are for the Kerr-McGee plant and the Georgia-Pacific gypsum board production facility in the Apex industrial area. No violations of ambient air quality standards have been reported for the pollutants monitored. Emissions from individual industrial developments should be evaluated on the basis of the emission rates, the size of the facility, seasonal variations in process emissions, and source-specific atmospheric dispersion characteristics.
4.6.8 Noise
The acoustic environment of the Dry Lake Valley can be classified as uninhabited desert or small rural communities (Section 4.1.8 ). However, several noise producers are adjacent to or within the 3,600-acre site. The major sources of noise would be associated with traffic on Interstate 15; which forms part of the eastern border of the site, the Union Pacific Railroad, which parallels Interstate 15, and the Apex industrial area, southeastof the site. On the site, the Nevada Power Company owns and operates an electrical substation, a phase shifter and an autotransformer, and has plans to construct four additional power plants. Meteorological conditions, such as wind, generate noise at the site.
4.6.9 Visual Resources
The landscape character of the Dry Lake Valley is typical of the Great Basin. Regional topography consists of mountain ranges arranged in a north-south orientation, separated by broad valleys. In addition to the natural surroundings, the existing viewscape includes an industrial area, U.S. Highway 93, Interstate 15, a railroad, power plant, and power transmission lines. The landscape at the Dry Lake Valley is common to the region, and because of the amount of cultural modification, the scenic quality has been designated as Class C. The average daily traffic on Interstate 15 is 12,000 to 13,000 vehicles (NDOT, 1993a). Therefore, the Dry Lake Valley would have a high visual sensitivity.
4.6.10 Cultural Resources
The Dry Lake Valley lies in southern Nevada, an area with a history that may span the past 10,000 years or more. Properties ranging from the early prehistoric period to historic transportation, mining, and ranching are known. When Europeans first entered the area around the Dry Lake Valley, they encountered groups of Southern Paiute people. Groups that are likely to have used resources found in the project area include the Moapa, Tule Springs, and Las Vegas bands (Steward, 1938; Stoffle and Dobyns, 1982). Geographically, the Dry Lake Valley extends from Apex to well within the Moapa River Indian Reservation. The area proposed for solar power development is within the Apex industrial area northwest of Interstate 15. It encompasses approximately 3,600 acres.
Table 4-42. Background air quality data for the Dry Lake Valley
| Average Period | |||||
| Nitrogen Oxidea (µg/m) | Annual | ||||
| 1. Kerr-McGee | 0.017 | ||||
| 2. Bonneville-Nevada’s Georgia Pacific Site | 1.620 | ||||
| Total | 1.640 | ||||
| Standard | 25.000 | ||||
| Available | 23.360 | ||||
| Sulfur Dioxideb (µg/m) | 3-hour | 24-hour | Annual | ||
| 1. Kerr-McGee | 0.010 | 0.004 | 0.001 | ||
| 2. Great Star | 100.100 | 30.500 | 5.000 | ||
| Total | 100.100 | 30.500 | 5.000 | ||
| Standard | 512.000 | 91.000 | 20.000 | ||
| Available | 411.900 | 60.500 | 15.000 | ||
| Total Suspended Particulate (µg/m) | 24-hour | Annual | |||
| 1. Kerr-McGee |
| 0.125 | 0.001 | ||
| 2. United Rock and Great Star | 4.600 | 1.480 | |||
| 3. Avena | 0.900 | 0.300 | |||
| 4. Georgia Pacific | 2.800 | 0.900 | |||
| 5. Bonneville-Nevada | 0.800 | 0.080 | |||
| Total | 9.200 | 2.800 | |||
| Standard | 37.000 | 19.000 | |||
| Available | 27.800 | 16.200 | |||
| a United Rock and Avena emit no nitrogen oxides from stationary sources; Great Star, and Georgia Pacific were approved prior to February 8, 1988 b No sulfur dioxide impact from United Rock, Avena, Georgia Pacific, Bonneville-Nevada. Source: Clark County, 1990a. | |||||
4.6.11 Occupational and Public Health and Safety
The Dry Lake Valley site proposed for siting a Solar Enterprise Zone facility is currently undeveloped desert. Baseline health and safety considerations associated with the environment include potential for heat stroke and exhaustion (primarily during summer months), dehydration, and poisonous spider and snake bites. Other physical hazards include tripping or stumbling hazards associated with the desert terrain.
4.6.12 Environmental Justice
Existing demographic conditions for Environmental Justice are discussed in Section 4.1.12 . This discussion includes conditions for the Dry Lake Valley.
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