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Table of Contents

Rock Formations

Stratigraphy

Mineral Resources

Economic Geology

Subsurface Rocks

Ground-water Resources

Ground-water Recharge

Ground-water Discharge

Availability

Chemical Character

Ground-water Regions

Records of Wells

References

Part 3--Ground-water Resources of Chase County

by Howard G. O'Connor

Ground-water Resources

Source

The ground water percolates slowly through the rocks in a direction determined by the topography and geologic structure until it is discharged through wells or springs, through seeps directly into streams, or by evaporation and transpiration in the valley areas.

Principles of Occurrence

According to their origin, the interstices of a rock may be classified as primary or secondary. Primary interstices are those which came into existence at the time the rocks were being formed. Secondary interstices are those developed by processes that affected the rocks after they were formed.

Secondary interstices, comprising joints, other fracture openings, and solution openings, are of primary importance in the consolidated rocks, whereas the primary or original interstices are of greater importance in the unconsolidated rocks with respect to water supplies, in Chase County as generally elsewhere.

The amount of water that can be stored in a rock is determined by the porosity of the rock. Porosity is the percentage of the total volume of a rock that is occupied by interstices. A rock is said to be saturated when all its interstices are filled with water or other liquids. The amount of water that a saturated rock formation will yield is known as the specific yield and may be defined as the ratio of (1) the volume of water which, after being saturated, it will yield by gravity to (2) its own volume. Because some water is left behind, held by capillarity, the specific yield is always less than the porosity.

The amount of water a rock formation may hold is determined by its porosity, but the rate at which it will yield water is determined by its permeability. The permeability of a rock formation is defined as its capacity for transmitting water under a hydraulic head and is measured by the rate at which the formation will transmit water through a given cross section under a given difference in head per unit of distance. A stratum of clay may have a porosity equal to that of a strata of sand, but, because of the small size of the interstices of the clay and the force of molecular attraction in fine-grained rocks, the clay may be almost impermeable under ordinary hydraulic gradients; however, a stratum of sand having an identical porosity may have a high permeability because of the relatively large interconnecting interstices which permit water to move through easily under the same hydraulic gradient.

Below a certain level in the earth's crust, the permeable rocks generally are saturated with water under hydrostatic pressure and are said to be in the zone of saturation. The upper surface of the zone of saturation is called the water table. All the rocks above the water table are in the zone of aeration, which ordinarily consists of three parts: the belt of soil water; the intermediate, or vadose zone; and the capillary fringe.

Unconfined Water

Confined Water

In areas where water is confined by alternating permeable and impermeable beds, a well may pass through several zones of saturation, each of which has sufficient permeability to supply water to a well. Confined water in permeable formations tends to move in the direction of dip of the formation. The quality and the quantity of water obtainable from these confined beds varies considerably, even in short distances, because of changes in lithology and degree of weathering, and in the amount of fracturing and solution that have occurred.

Artesian conditions.--The level at which water stands in wells may be called the piezometric or pressure-indicating surface. Where the top of the zone of saturation occurs in a permeable formation, the piezometrie surface coincides with the water table, and the water is said to be under normal pressure. If water is confined between relatively impermeable beds and the level at which water will stand in a well is below the top of the zone of saturation, the water is said to be under subnormal pressure; but if the level at which water will stand in a well is above the zone of saturation, the water is said to be under artesian pressure. An artesian well that flows at the land surface is a flowing artesian well.

Areas of artesian flow.--In Chase County there are two known areas where flowing artesian wells occur.

In one area three flowing wells were drilled in 1922, to a depth of somewhat more than 100 feet, on the William Selves ranch in the NE SE sec. 27, T. 20 S., R. 7 E. The northeasternmost, No. 20-7-27da3 (P1. 6F), of the three wells had sufficient head to flow water to the second story of a farmhouse adjacent to the well. Wells 20-7-27da3 and 20-7-27da2 each flow less than 1 gallon a minute and are not used. Well 20-7-27da1, the southeasternmost of the three flowing wells, is used to supply water for all domestic purposes at the Selves ranch. Table 6 includes a chemical analysis of the water from this well. The artesian flow from the well through a one-half inch pipe was measured as slightly more than 3 gallons per minute by A. R. Leonard and H. G. O'Connor. The total discharge from the three flowing wells in 1947 was approximately 500,000 gallons.

There are two flowing wells about 1 1/4 miles south of the Selves ranch on the James C. McNee ranch in the SW SE sec. 34, T. 20 S., R. 7 E., and NE NE sec. 3, T. 21 S., R. 7 E. These wells are reported by their owner to be approximately 100 feet deep.

There is one flowing well on the Mildred Morse farm in the SE SE sec. 27, T. 22 S., R. 6 E. This well is reported to be 20 to 30 feet in depth and to have been drilled about 1937. The initial hydrostatic head was reported sufficient to force water approximately 13 feet above the land surface. In the fall of 1947 this well was flowing an estimated 5 gallons a minute through the well easing and was leaking around the outside of the casing, the discharge by leakage accounting for most of the flow (P1. 6B).

Prior to the drilling of the Morse well, a well owned by School District No. 45 of Burns, Kansas, in the SW SW sec. 26, T. 22 S., R. 6 E., had flowed, but it ceased to flow when the Morse well was drilled. A chemical analysis of the water from the school well (22-6-26cc) is given in Table 7.

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