Kirtland Federal Complex is located on a high, arid mesa about five miles east of the Rio Grande in Bernalillo County, New Mexico. The mesa is cut by the east-west trending Tijeras Arroyo, which drains into the Rio Grande. The east side of the Kirtland Federal Complex north of Tijeras Arroyo is bounded by the southern end of the Sandia Mountains and south of Tijeras Arroyo by the Manzanita Mountains (foothills of the Manzano Mountains). Most of the area is relatively flat, sloping gently westward toward the Rio Grande. However, the eastern portion of the Complex extends into the canyons of the Manzanita Mountains. The western slope of the Manzanita Mountains facing the base is precipitous and rough and has numerous arroyos. Elevations range from 4920 feet (ft) at the Rio Grande to 7988 ft at the Manzano Lookout Tower in the Manzano Mountains. The mean elevation of the Kirtland Federal Complex is 5348 ft.
The Department facilities are surrounded by the Kirtland Federal Complex and include some co-use agreements on United States Air Force (USAF) property. An area of the Manzano Mountains in the eastern portion of the approximately 80 square-mile (sq mi) Kirtland Federal Complex has been withdrawn from the USFS for the exclusive use of the USAF and the Department.
Located to the north and west of the Kirtland Federal Complex, Albuquerque is the largest population center in Bernalillo County. The 1990 census figure shows an Albuquerque population of 384,736. The greater Albuquerque area, including Rio Rancho and Corrales, has approximately 422,700 inhabitants. A 1994 projection of the Metropolitan Statistical Area (MSA) population, which includes Bernalillo County, Valencia County, and Sandoval County, is 645, 500. The Isleta Indian Reservation borders the Kirtland Federal Complex on the south. The Pueblo of Isleta, located approximately 8 mi southwest of the base, had a population of 1703 in 1990 and the wider reservation area had a total population of 2171 in 1990.
Weather in the Albuquerque/Bernalillo County area is characterized by low precipitation; wide temperature extremes; frequent, drying winds; heavy rain showers, usually short in duration and often with erosive effects; and erratic, seasonal distribution of precipitation. Albuquerque air temperatures are characteristic of high-altitude, dry continental climates. The average annual precipitation is 8.2 inches (in.). Winter months are typically dry with less than two inches of precipitation normally recorded. Strong winds, often accompanied by blowing dust, occur mostly in late winter and early spring.
General Geologic Description
The Kirtland Federal Complex is located in the eastern portion of the Albuquerque Basin, on a relatively flat mesa southeast of the city of Albuquerque. The Albuquerque Basin is one of a series of north-south aligned structural grabens (blocks of downthrown crust) that make up the Rio Grande Rift. The rift is over 600 miles long and runs from southern Colorado to western Texas and northern Mexico. The Rio Grande Rift was created by movement of the Colorado Plateau and the western portion of the North American Continent relative to the remainder of the North American continent. Weaknesses in the continental structure allowed the western side of the continent to break away and move faster than the eastern side. This breaking, or faulting, allowed for blocks of crust to drop relative to the surrounding land surface, forming grabens and creating the rift. Subsequent basin-filling by sedimentary action has resulted in the current geography, which includes the Rio Grande whose course is controlled by the surface expression of the rift. The generally recognized boundaries of the Albuquerque Basin (Figure 2.2-1) include the Sandia and Manzano uplifts to the east, the Nacimiento uplift to the north, the Puerco fault zone to the west, and the Socorro basin to the south. The Albuquerque Basin is approximately 100 miles from north to south and 50 miles from west to east.
Sedimentology
Soils in the Albuquerque Basin range from fine-grained clays and silts near the river channel to well-drained sands and sandy loams on the mesas and highlands. Figure 2.2-2 lists and locates the soil types mapped within the Kirtland Federal Complex.
The Santa Fe Group makes up the predominant surface exposures and consists mainly of fan shaped deposits eroded from the Sandia, Manzano, and Manzanita mountains. These fan-shaped deposits are composed of coarse, poorly to moderately sorted sediments ranging in size from clay to boulders, and variable thickness from inches to several feet. Individual units pinch out laterally or are truncated by erosional forces, creating limited continuity in map view. Flooding events may deposit very thin, fine-grained layers over a wide area.
Seismicity (Earthquake Activity)
Seismic activity (earthquakes) in the Albuquerque area are infrequent and usually of low intensity. In the Albuquerque area, the largest reported event of this century occurred on January 4, 1971, and registered 4.7 on the Richter scale. Property damage caused by this earthquake was limited to cracked plaster and a few broken windows.
Albuquerque and the Kirtland Federal Complex lie within Seismic Risk Zone 2, as defined by the International Conference of Building Officials (ICBO) Uniform Building Code. Seismic Risk Zone 2 is a classification of moderate potential for damage to structures from seismic activity. All Department facilities are designed and constructed in compliance with building codes current during the design process.
General Hydrogeologic Description
The Albuquerque Basin is the third largest of the structural basins of the Rio Grande Rift and is home to the largest population center along the rift. The city of Albuquerque and its surrounding area populations rely solely on groundwater as their potable and industrial water source. The relationship between the geology of the basin and the hydrogeologic parameters of the water source moving through it will be critical in the future development of the area.
Hydrogeologic Structure
The primary sedimentary units in the Albuquerque Basin are associated with the Santa Fe Group. This formation consists of alluvial material (outwash deposits from the surrounding highlands) and fluvial materials (river sediments) that have been reworked by erosional forces (wind and water). Volcanism in the area occurs as basaltic lava flows and layers of ash that have been deposited directly or transported into the rift area.
Layered sediments create zones of variable porosity and permeability in a vertical direction that may act to impede groundwater flow. For example, a lava flow (low porosity and permeability) underlying a series of sandy or gravelly deposits (high porosity and permeability) would serve as a barrier to downward migration of groundwater. In the Albuquerque area, the variety of sediment types and depositional processes has resulted in a very complex "layer cake" of sedimentary units. The variable nature of the sediments and the processes that deposited them makes it difficult for geologists to predict specific conditions beneath the surface.
Superimposed upon this complex layered sedimentary structure are the rift zone faults present throughout the area. These faults generally follow the eastern and western edges of the rift, and are generally oriented north to south. Three major faults traverse the Kirtland Federal Complex, and converge near Tijeras Arroyo beneath the Complex (Figure 2.2-1). The Hubbell Spring Fault runs southward from Kirtland Federal Complex to approximately the Socorro county line. This fault delineates the western edge of the Hubbell Bench, which lies at the foot of the Manzano Mountains. The second major fault is the Sandia Fault, which runs northward from Kirtland to an indeterminate point in Sandoval County. The Sandia Fault may be an extension of the Hubbell Spring Fault. This fault delineates the foot of the Sandia Uplift and is a high-angle normal fault, down to the west. The third major fault in the area is the Tijeras Fault, which is a scissors-type fault (down to the southeast) that runs from Kirtland to the northeast, and is believed to be the structural boundary between the Sandia and Manzano mountains.
Groundwater Depth and Flow Direction
The presence of the faults described in the previous section has a direct bearing on the movement and occurrence of groundwater in the vicinity of the Kirtland Federal Complex. Complicating the issue of groundwater depth and movement are changes to the steady-state condition induced by pumping of groundwater from city, private, and industrial wells. In general, groundwater is located at a greater relative depth near the foothills (except near recharge areas at the mouths of canyons), and groundwater depth becomes relatively shallower near the river in the inner valley. Flow direction is consistently downbasin (south), with local variations due to groundwater pumping (i.e. westward flow near KAFB), geologic structure, or shallow influences near the river.
Early studies of groundwater flow showed movement to be toward the southwest. Pumping of water wells has locally shifted flow direction from a southwesterly to a northwesterly direction, toward the city wellfields (Figure 2.2-3).
Ecology
Four major North American physiographic and biotic provinces meet in the area of the Kirtland Federal Complex: the Great Basin, the Chihuahuan Desert, the Rocky Mountains, and the Great Plains. The characteristics of the Great Basin are the most predominant of the four, but biotic communities of the other three provinces also exist within the Kirtland Federal Complex.
Four vegetation formations are found in these communities: grassland, woodland, riparian scrubland, and riparian woodland. Riparian woodland and riparian scrubland are limited to arroyos and canyons. Grasslands and woodlands dominate the rest of the area (Figure 2.2-4).
Wildlife communities within the Kirtland Federal Complex generally include amphibians, reptiles, birds (breeding and migratory), and mammals. Their diversity and abundance vary at given locations depending on the quantity and quality of habitat. When considering the habitat of a given species, food, water, and shelter are as important as corridors of travel between habitat areas, the potential for human intrusion, and the availability of breeding sites. In general, wildlife communities living within the boundaries of the Kirtland Federal Complex are typical of those found in similar woodland and grassland habitats in central New Mexico.
Biological surveys have been conducted in areas that contain SNL ER Project sites. The major vegetation type associated with these areas is comprised of woody shrubs, cacti, and grasses. Some areas also have vegetation such as Russian thistle, canaigre, globemallow, broom snakeweed and rabbitbrush, which are types of vegetation usually associated with highly disturbed areas. Although no species of special concern were observed in the immediate vicinity of these ER sites, several species of special concern were observed in the grassland habitat surrounding the sites.
More detailed information about the ecology of Kirtland Federal Complex and Department ER sites can be found in the individual Management Area/Sector Workbooks that have been prepared for the CAB.