Geology topics
Publications and source records attributed to K. D. Peter.
The geochemistry of water in five aquifers and two confining units in the Williston Basin of the Northern Great Plains is similar and is controlled by halite dissolution. In areas outside the Williston Basin ground-water is fresh and controlled by the solution chemistry of carbonate and sulfate minerals.
The Inyan Kara, Minnelusa, and Madison aquifers are the principal sources of ground water in the northern Black Hills, South Dakota and Wyoming, and Bear Lodge Mountains, Wyoming. The aquifers are exposed in the Bear Lodge Mountains and the Black Hills and are about 3,000 to 5,000 ft below the land surface in the northeast corner of the study area. The direction of groundwater movement is from the outcrop area toward central South Dakota. Recharge is by infiltration of precipitation and streamflow is by springs and well withdrawals. All three aquifers yield water to flowing wells in some part of the area. Measured and reported well yields in each of the three aquifers exceed 100 gal/min (gpm). A well open to the Minnelusa Formation and the upper part of the Madison Limestone yielded more than 2 ,000 gpm. Water from the Inyan Kara aquifer may require treatment for gross alpha radiation, iron, manganese, sulfate, and hardness before use in public water systems. Water from the Minnelusa aquifer in the northern one-half of the study area may require treatment for sulfate and hardness before use in public water systems. Water from the Madison aquifer in the northern one-half of the study area may require treatment of fluoride, gross alpha radiation, sulfate, and hardness before use in public water systems. Water from the Minnelusa and Madison aquifers in the southern one-half of the study area, though very hard (more than 180 mg/L hardness as calcium carbonate), is suitable for public water systems and irrigation. Flow between the Minnelusa and the Inyan Kara aquifers appears to be insignificant, based on the results of a digital model results. The model indicated there may be significant recharge to the Minnelusa and Madison aquifers by leakage between these two aquifers and perhaps deeper aquifers. (Author 's abstract)
The purpose of this investigation was to describe the water table configuration and its temporal variations, estimate aquifer properties, and evaluate the interaction of groundwater and surface water in the inner valley of the Rio Grande in southern Albuquerque, New Mexico, where groundwater contamination is a continuing concern. The upper 150 ft of sedimentary deposits in the inner valley, mostly alluvium that consists of cobbles, gravel, sand, silt, and clay, was emphasized because of its susceptibility to contamination. A map of the water table on February 28, 1986 shows that flow generally is parallel to the river and the gradient is approximately 5 ft/mi or 0.0001. In areas affected by municipal and industrial groundwater withdrawals, declines may exceed 10 ft, and the water table gradient is as much as 20 ft/mi or 0.004. The gradient also is steeper near drains, particularly during the irrigation season. In the area east of the community of Mountainview the direction of water movement may have reversed between 1936 and 1986; flow near appears to be toward the east or southeast. Groups of four piezometers, each screened at a different depth, were monitored to describe seasonal changes of the water table. Vertical gradients between piezometers ranged from 0.014 upward to 0.047 downward from July 1985 to June 1986, but were downward most of the year, particulary during the irrigation season. The horizontal hydraulic conductivity of a 15-ft-thick clay and silt bed beneath Rio Bravo Boulevard is estimated to be 0.0001 ft/day. The average interstitial velocity down through this bed is estimated to range from about 0.0002 to 0.0005 ft/day. The fluctuations of the water table at the piezometers nearest the Rio Grande do not appear to be affected by the riverside drain.
Identification of the presence of volatile organic compounds in liquid-waste lagoons in New Mexico at the Lee Acres landfill, beneath a refinery south of the landfill, and in nearby residential wells has led to an hydrologic investigation of the area. The alluvium underlying an arroyo adjacent to the landfill mostly consists of fine to coarse quartz sand with some silt, gravel, and clay zones. Thickness of the alluvium measured in 12 drill holes ranged from 13.7 to 61.5 ft. A seismic survey indicates that buried channels are incised as much as 26 ft into the bedrock surface in some areas. The depth to water in seven piezometers ranged from 26.6 to 34.9 ft. The configuration of the water table in the alluvium indicates that groundwater flow is controlled by unidentified recharge north of the landfill, recharge from a pond southeast of the landfill, discharge to pumping wells, discharge to the alluvium of the San Juan River south of the study area, and hydraulic conductivity of the alluvial material. There also may be additional recharge to or discharge from the underlying Nacimiento Formation and recharge from runoff in the arroyo. Terrain-conductivity measurements indicate that the water in the alluvium southwest of the landfill may be more conductive than water in the underlying sandstone. (USGS)
An evaluation made in cooperation with the U.S. Bureau of Reclamation of the availability and quality of water from the bedrock aquifers in the Rapid City area, South Dakota, concluded that Madison aquifer has the greatest potential for additional development of the three major aquifers investigated (the Inyan Kara, the Minnelusa, and the Madison). Ground-water availability and quality were evaluated on the basis of unit thickness and depth, potentiometric-surface altitudes and gradients, estimated recharge and discharge rates, estimated aquifer transmissivities and storage coefficients, reported yields of existing wells, and concentrations of ions in the water that may affect its use as a community supply. The Inyan Kara aquifer has the least potential for additional development because of reported small well yields , the proximity of the outcrop, and concentration of radium-226 exceeding 5 picocuries per liter. The Minnelusa aquifer is unsuitable for development in the eastern two-thirds of the study area because the concentrations of dissolved solids and sulfate commonly exceed the recommended maximum level for community water supplies. The Madison aquifer has the greatest potential for additional development because it has the greatest recharge rate, has areas with significant fracture permeability, yields as much as 500 gallons per minute to wells, and has satisifactory water quality, though it is hard (hardness 120 to 180 milligrams per liter) to very hard (hardness greater than 180 milligrams per liter). (USGS)
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