All of the public water supplies and nearly all of the irrigation, domestic and stock supplies in Meade County are obtained from wells. Although a few dug and driven wells are in use, most of the wells in the county are drilled. Several types of drilling methods have been used.
Principles of Recovery
When water is withdrawn from a well there is a difference in head between the water inside the well and the water in the material outside the well. The water table or piezometric surface in the vicinity of a well that is discharging water has a depression somewhat in the form of an inverted cone with the apex at the well. Under artesian conditions this cone is imaginary and its apex is the point of discharge of the well. The draw-down and the diameter of the cone of depression, or pressure release, vary at any given well directly with the quantity of water produced from the well, and may vary considerably among several wells producing the same quantities of water. As a general rule, an artesian well producing the same quantity of water as a nonartesian well from similar material will create a cone of depression whose diameter is several times as large as that of a cone of depression developed under nonartesian conditions.
The specific capacity of a well is its rate of yield per unit of draw-down, and is usually stated in gallons a minute per foot of draw-down. Thus, a well yielding 1,000 gallons a minute with a draw-down of 10 feet would have a specific capacity of 100 gallons a minute per foot of draw-down. When a well is pumped the water level drops rapidly at first and then more slowly, but may continue to decline for several hours or days. In testing the specific capacity of a well, therefore, it is important to continue pumping until the water level remains approximately stationary. When the pump is stopped, the recovery is likewise rapid at first, but tapers off slowly and may continue long after pumping has ceased. For additional details on this subject the reader is referred to Meinzer (1923a, pp. 60-68).
Obviously, since the cost of pumping water increases with the draw-down, material saving in the cost of pumping can be effected by increasing the specific capacity of a well by modern methods of well construction.
In some parts of Meade County there are a few dug wells still in use for domestic and stock supplies. Many of these are quite shallow and obtain meager supplies of water from alluvium along minor stream valleys. Because of their large diameter, dug wells provide large infiltration area and considerable storage of water. They are more apt to fail during dry seasons and are more subject to contamination, however, than the deeper drilled wells. Most dug wells for domestic or stock use are from 2 to 4 feet in diameter and are curbed with stone or wood. One well (215) was dug to the first artesian water-bearing bed, and so has the characteristics of an artesian well.
Some of the shallow wells in loose surficial material, such as well 39, have been bored by use of a hand auger. Most of these wells were bored to the water table or a short distance below it and then a screened well point, was driven into the bottom. In some wells a 6-inch galvanized-iron casing is placed in the bored part of the well, but in others the walls of the hole are allowed to cave in around the pipe.
Methods of construction--Most of the drilled wells in Meade County have been constructed by one of three methods, namely: cable-tool percussion, hydraulic-rotary, or a modified hydraulic jetting method. All of these methods have been used in conjunction with hand auguring through the loose surficial material.
Portable cable-tool percussion or "spudding" machines employ a heavy chisel-edged drill bit or other tool suspended by a rope or cable to which a reciprocating motion is imparted by the drilling machine. The drill crushes the rock into small fragments and churns it into suspension in the water that is poured into the well, if water is not encountered in the formation that is being drilled. At intervals the drilling cuttings and sludge are removed from the hole with a bailer or sand pumps. Drilled water wells range in diameter from 4 to 12 inches or more, but wells for domestic and stock use commonly are 6 inches in diameter. Most of the wells drilled into the Permian redbeds and some of the wells in the Tertiary and Quaternary deposits were put down by this method.
In the hydraulic-rotary method a hollow drill stem equipped with a cutting bit is rotated in the hole, and either water or mud is forced down the stem and out of the bit, thus creating an upward circulation of fluid along the sides of the hole which carries the cuttings to the surface. The mud also serves to prevent caving of loose materials until the casing is placed. The diameter of wells drilled by this method ranges from 1 1/2 inches to 2 feet or more. Many of the irrigation wells of large diameter were drilled by this method.
A somewhat specialized type of jetting process was used extensively during the period of maximum drilling activity in the artesian basin, and is still used to a lesser extent in the basin and on the adjacent High Plains. The homemade equipment used is capable of penetrating only relatively unconsolidated deposits. In this process joints of galvanized-iron pipe 1 1/ 2 or 2 inches in diameter generally are used for the drill stem, and a bit is fitted onto the lower end. Water is pumped down the stem; and, in contrast to the hydraulic-rotary method, the jet of water against the bottom of the hole is an important factor in loosening the material, which is carried to the surface by the upward moving column of water between the stem and the sides of the hole. The drill stem generally is alternately raised and lowered, and rotated in the hole, thus aiding the force of the water in loosening material at the bottom. After the holes are completed about 30 feet of casing generally is driven into place, but many of the wells drilled by this method have no outer casing, particularly the early wells in the artesian basin. There are better methods for jetting wells through the inside of the casing, adding sections of casing as the hole is deepened. The completed hole is thus eased to the bottom and may be screened at the bottom.
Wells in consolidated rocks--The wells in this area that obtain water from the consolidated Permian rocks are cased through the overlying unconsolidated deposits or weathered rock, and the casing generally is driven several feet or more into the bedrock. Thus, the water may enter the well along its entire uncased portion wherever the rock is water-bearing. Wells finished in this way are called open-end wells because the water enters only below the lower end of the casing. A few of the wells ending in bedrock in Meade County have been cased to their full depth and have perforated casing in the lower part.
Wells in unconsolidated deposits--Many of the wells in unconsolidated deposits in Meade County were constructed by drilling or boring a hole a short distance below the water table, setting a casing of galvanized iron, and driving a screened well point some distance below the bottom of the hole. Many of the early flowing wells were cased only at the top, although more recently the usual practice has been to case the full depth and to perforate the lower part of the casing.
Several methods have been used to increase the intake area in nonflowing wells and thus increase the yield. The simplest of these methods is to perforate those portions of the casing that are opposite the water-bearing beds. In order to know where to perforate the casing and to permit the selection of the proper size for the perforations, samples of material should be taken every few feet as drilling progresses, and the depth and thickness of water-bearing beds carefully recorded. A more efficient method of increasing the intake area of a well is by the use of well screens. Well screens (or strainers) are manufactured in many different types and sizes. The grain size of the water-bearing material determines the size of openings to be used in the screen. In places where large supplies of water are sought from material not sufficiently coarse to be held back by the screen, a layer of coarser material may be placed around the screen either artificially or by pumping out the finer particles of water-bearing materials, leaving a residual layer of natural gravel. Most so-called gravel-wall or gravel-packed wells in Meade County are constructed by first drilling a somewhat larger hole (30 to 60 inches in diameter) and temporarily casing to the bottom; an inner screen and casing of smaller diameter is lowered into place; the annular space between the two casings is filled with selected gravel of uniform texture; and the outer casing is withdrawn all or part way. The effective diameter of the well is thus greatly increased by the layer of gravel which itself acts as a screen to reduce the entrance velocity and permit the entrance of large supplies of water. It should be remembered that the only advantage attained by this method is to increase the permeability of the material adjacent to the screen; and, where water is supplied from well-sorted gravel, as it is in many parts of Meade County, the addition of gravel around the screen merely increases the cost of construction without increasing the effectiveness of the well.
Methods of Lift and Types of Pumps
Water is obtained from many of the domestic and stock wells in Meade County by windmill-operated lift or force pumps. The cylinders or working barrels in lift pumps and force pumps are similar and are located below the land surface either above or below the water surface, but a lift pump is capable of discharging water only at the pump head, whereas a force pump can raise water above this point--as to an elevated tank. Pitcher pumps are used on some dug or bored wells where the water level is within the suction limit. Most of the pitcher pumps and a few of the lift and force pumps are hand operated.
Several types of power-driven pumps are in use on the irrigation and municipal wells in the county. These pumps are, without exception, turbine pumps and are powered by electric motors, stationary gasoline engines and tractor engines. Several large centrifugal pumps have been used in the past, and municipal wells of the city of Meade formerly were pumped by air lift.
Most of the flowing artesian wells are not equipped with pumps, but a few are pumped in order to obtain a larger yield than is obtained by natural flow. Most of the flowing wells discharge onto the surface, into tanks, or are connected with individual home water systems.
In Meade County a few domestic and stock supplies and some irrigation supplies formerly were derived from springs. In 1939, however, spring water was used extensively only in Meade County State Park, where it supplied the C. C. C. Camp, hatchery ponds, and some irrigation water used on the grounds of the park.
Most of the springs in the county are artesian springs, from which the water issues under artesian pressure. There are also a few gravity springs, however, particularly in the southeastern part of the county, where water issues from the base of the Tertiary deposits where they overlie relatively impervious Permian rocks, and along Crooked Creek, where seepages occur from the body of shallow ground water into the stream. With respect to the quantity of water discharged, Meinzer (1923a, p. 53) has devised the following classification of springs for convenient use in the United States.
Table 6--Meinzer's classification of springs with respect to discharge.
|First||100 second-feet or more||Fifth||10 to 100 gallons a minute|
|Second||10 to 100 second-feet||Sixth||1 to 10 gallons a minute|
|Third||1 to 10 second-feet||Seventh||1 pint to 1 gallon a minute|
|Fourth||100 gallons a minute
to 1 second-foot
(448.8 gallons a minute)
|Eighth||Less than 1 pint a minute
(less than 180 gallons or
about 5 barrels a day)
In Meade County there are no springs of first or second magnitude, but one spring on Big Springs ranch, which has a discharge of 840 gallons a minute, and the springs in Meade County State Park, which have an aggregate yield of about 680 gallons a minute, are of third magnitude. The other springs in the county are of fourth magnitude and less.
Kansas Geological Survey, Geologic History of Kansas
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Web version February 2004. Original publication date Dec. 1942.