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Additional Research Needs
Additional research is needed to understand in more detail the relation of water chemistry to structure and faulting, seasonal water-quality changes with depth, water quality in relation to the mineralogy of the sediment columns, oxidizing and reducing conditions, organic content, and bacterial activity in the aquifers. This information will help in the siting of wells and screens and/or in treating ground water to obtain water that meets Federal and State quality standards.
More detailed information is needed in some of the counties to define more accurately the location, character, and extent of buried valleys, the character of valley-fill deposits, and the ground-water-flow paths between recharge and discharge areas. A better understanding of the glacial processes involved in formation of the buried valleys and better knowledge of the stratigraphy and correlations could help to locate channels and the most promising units for water supplies.
The role of improperly constructed wells, improperly plugged test holes, and unserviceable or abandoned wells in providing pathways for the rapid transport of shallow contaminated ground or surface water to the deeper confined aquifers and to seasonal water-quality changes needs further investigation. This will help to define major problems and to suggest possible solutions and future methods of minimizing additional contamination.
Conclusions
Ground water in the glacial deposits of a 12-county area of northeastern Kansas is an important resource for an area that is increasing in population size and water use. Maps for each of the 12 counties show the depth to bedrock, the depth to water, the total sand and gravel thickness, the estimated yield of wells, and the thickness of saturated unconsolidated deposits, which are largely glacial deposits. Plate 1 shows the bedrock topography and is based on geologic and topographic maps, about 5,000 water, oil and gas, and well logs, and measured sections. These maps provide a basis for the further exploration and development of ground-water resources in glacial aquifers. Denne et al. (1990a) list the location and numerical hydrologic information for all the wells used in the study.
The location of the preglacial drainageways shown in fig. 2 and plate 1 indicates that buried valleys may be up to 3 mi (5 km) wide, 400 ft (120 m) deep, and more than 75 mi (120 km) long. Well yields in these deposits may be as high as 900 gpm (0.06 m3/s) but more commonly are less than 500 gpm (0.03 m3/s). Water levels are commonly between 5 ft (2 m) and 50 ft (15 m) below land surface but locally exceed 100 ft (30 m).
The greatest ground-water pumpage in the 12 northeastern Kansas counties is from alluvial aquifers, primarily in the Missouri and Kansas River valleys. The second largest source of ground-water pumpage is from glacial aquifers, and the Pennsylvanian and Permian bedrock aquifers are the source of the least amount of ground-water usage.
Historical water-quality data for more than 1,200 wells provide a picture of the general water quality of ground water from the glacial, alluvial, and bedrock aquifers. In 1981, 143 new water samples were collected from wells with geologic log information and known construction characteristics. These samples were analyzed under controlled conditions of sampling, handling, and analysis. Glacial aquifers contain water of the calcium bicarbonate type, which is generally of good quality. Locally, the concentrations of nitrate, sulfate, chloride, iron, and manganese occur in excess of drinking water standards. The 143 wells sampled include samples from nine bedrock aquifer wells, 26 alluvial aquifer wells, and 108 glacial aquifer wells. Denne et al. (1990b) list all the analyses of water samples collected during 1981.
Information given in this report should provide the basis for efficiently locating, developing, and protecting ground-water supplies from the glacial deposits in buried Valleys.
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Kansas Geological Survey, Geohydrology
Placed on web March 1, 2015; originally published 1998.
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