Improvements have been made at a few of the springs in the area underlain by Cretaceous sandstone (Pl. 1), and some of the springs are used to supply water to stock ponds. A few small springs, some of which have been developed, occur north of Wichita. Most of the springs in this area are undeveloped and a comparatively small quantity of ground water is recovered from them.
Dug wells are excavated by picks and shovels or by power machinery. They are generally between 2 and 10 feet in diameter and comparatively shallow. Many of the earlier wells in this area were dug by hand, but most of these have since been replaced by drilled wells. At present there are some dug wells in the areas underlain by Permian and Cretaceous rocks. Many of the farm wells in the McPherson formation are dug for part of their total depth and small diameter pipes and sand points are driven below the water table.
The dug wells in this area are curbed with stone or timber. They generally are poorly sealed and may be contaminated by the entrance of surface waters. Because of the difficulties of digging by hand below the water table, dug wells generally are excavated only a few feet below the water table and are, therefore, more likely to fail during a drought than are drilled wells, which generally extend many feet below the water table.
Many wells in this area are driven, especially in the alluvium of the Arkansas and Little Arkansas rivers. This type of well is made by driving a small-diameter pipe (equipped at the bottom with a screened drive point) down below the water table. Such wells can be put down only where the water-bearing material is sufficiently permeable to permit water to flow freely into the screened drive point, where the material is soft enough, and where the water table is shallow. Generally a hole is augered by hand as deep as possible, then the pipe and screened drive point are put in and driven into the water-bearing material. Most driven wells are equipped either with hand-operated pitcher pumps or with windmills and submerged cylinders, and are used for domestic and stock purposes.
Many of the domestic and stock wells and most of the public-supply, industrial, and irrigation wells in this area are drilled wells. Most of the smaller wells were drilled by means of portable cable-tool or hydraulic-rotary drilling machines. Most of the larger municipal and industrial wells were drilled by means of an orange peel bucket (Pl. 26B) and are known as caisson wells. A few of these wells, however, were drilled by the hydraulic rotary method. The drilled domestic and stock wells are 2 to 8 inches in diameter and those used for public supply and industrial purposes range from 8 to 50 inches. Drilled wells generally are cased with galvanized-iron, wrought-iron, or steel casing.
Construction of wells in consolidated rocks. - Many of the wells in the parts of the area underlain by Cretaceous rocks and Permian shale are drilled into consolidated rocks. Most of these wells are open-end wells; that is, the hole is cased through the overlying soil and several feet into the consolidated rocks, but the lower part of the hole is not cased. Holes drilled into consolidated rocks will as a rule stand open without casing, but it is sometimes necessary to extend the casing to the bottom of the hole to prevent the walls from caving. Small perforations generally are cut into the casing opposite the water-bearing beds in those wells that are cased from top to bottom.
Construction of wells in unconsolidated rocks.--Most of the drilled wells in this area obtain water from unconsolidated sand or gravel. It is necessary to case these wells the full depth of the hole in order to prevent caving of the wells. In some wells the casing is open only at the bottom, but in others the casing has been perforated in the lower part. Perforating the casing greatly increases the area of intake, and thus the specific capacity of the well is increased and the entrance velocity of the water is reduced. Well screens are used in some wells to prevent fine sand from entering the well and to increase the intake area.
Most of the municipal and industrial wells in this area are constructed by excavating a hole of large diameter and sinking a blank temporary casing as the unconsolidated material is removed. When the excavation is completed a well screen or perforated casing of smaller diameter than the hole is then lowered into place and centered opposite the water-bearing beds. Blank casing extends from the screen to the surface. The annular space between the inner and outer casings then is filled with carefully sorted gravel - preferably of a grain size slightly larger than the openings in the screen or perforated casing, and also just slightly larger than that of the water-bearing material. The outer casing is then withdrawn from the hole, except in the upper part for sanitary reasons, and ground water enters the well through the gravel packing.
The logs of some of the test holes drilled during the investigation reveal that in some places the water-bearing materials are sufficiently coarse and well sorted that large yields may be obtained without gravel packing. In such places less expensive wells employing well screens or slotted casings, but without gravel packing, are satisfactory. In places where the water-bearing materials are fine-grained or poorly sorted, however, the gravel-packed wells have several advantages that offset the greater initial cost. The envelope of selected gravel increases the effective diameter of the well, reduces the entrance velocity of the water, and increases the yield of sand-free water. The drawdown generally is less in gravel-packed wells and the cost of pumping is correspondingly less.
A report (Davison, 1939) containing a description of different types of pumping plants, the conditions for which each is best suited, construction methods, and a discussion of construction costs is available from the division of water resources of the Kansas State Board of Agriculture. The reader is also referred to a report by Rohwer (1940) in which the various methods of constructing irrigation wells are described.
Methods of lift
Many of the domestic and stock wells in this area are equipped with lift or force pumps in which the cylinders are below the pump heads and may be far below the surface. Most of these pumps are operated by windmills. In parts of the area in which the depth to water is less than 15 feet, many wells are equipped with hand-operated pitcher pumps that have the working parts at the base of the pump heads.
Most of the large municipal and industrial wells are equipped with turbine pumps operated by electric motors. Some of the municipal wells are equipped with horizontal centrifugal pumps driven by electric or gasoline motors.
Kansas Geological Survey, South-central Kansas
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Web version April 2005. Original publication date July 1949.