When water is withdrawn from a well, there is a difference in head between the water inside the well and the water in the surrounding material at some distance from the well. The water table in the vicinity of a well that is discharging water has a depression resembling in form an inverted cone, the apex of which is at the well. This depression of the water table is known as the cone of influence or cone of depression and the surface area underlain by it is known as the area of influence. In any given well the greater the pumping rate, the greater the drawdown (lowering of the water level, commonly expressed in feet).
The capacity of a well may be defined as the rate at which it will yield water after the water stored in the well has been removed. The capacity depends upon the quantity of water available, the thickness and permeability of the water-bearing bed, and the construction and condition of the well itself. The capacity of a well is generally expressed in gallons a minute. The known or tested capacity of a well is generally less than its total capacity; however, some.wells are pumped at their total capacity.
The specific capacity of a well is its rate of yield per unit of drawdown and is determined -by dividing the tested capacity in gallons a minute by the drawdown in feet. Well 4-7-30da2 at Jewell City had a yield of about 2 gallons a minute and a drawdown of 14 feet. The specific capacity of that well, therefore, is 0.14 gallon a minute per foot of drawdown, or simply 0.14.
When a well is pumped, the water level drops rapidly at first and then more slowly, but it may continue to drop for several hours or days. In testing the specific capacity of a well, therefore, the well must be pumped until the water level remains approximately stationary. When the pump is stopped, the water level rises rapidly at first, then more slowly, and may continue to rise long after pumping has ceased.
In Jewell County, ground water is recovered from dug, drilled, and bored wells. No driven wells were observed, but some driven wells may be in use in the Republican Valley.
Dug wells are wells that have been excavated by hand, generally with pick and shovel. They are walled with wood, rock, concrete, brick, or metal. They are generally less than 60 feet in depth and are from about 2 to 18 feet in diameter. Dug wells are more subject to surface contamination than are properly constructed drilled wells; nevertheless, in Jewell County dug wells are generally preferable for farm wells because the water-bearing material has a low permeability, and the wells have a low specific capacity. For intermittent pumping, a large dug well acts as a storage reservoir for collecting water during a non-pumping period, and it will then furnish moderate quantities of water for short periods of pumping. At one time nearly all municipal wells in Jewell County were large-diameter (10 to 18 feet) dug wells and were equipped with large-capacity pumps for intermittent pumping. More recent municipal wells were drilled and equipped with lower capacity pumps for continuous pumping.
Many wells in the unconsolidated surficial deposits in Jewell County are bored and cased with tile. They are made by hand augers or posthole diggers and by a horse- or power-driven auger. They range from about 6 inches to 22 inches in diameter but are commonly about 12 inches. The deepest bored well that was measured was 138.6 feet (well 1-8-11cc).
A drilled well is one that is excavated by a percussion or rotary drill. In Jewell County, most of the drilled wells were drilled by the percussion method with portable cable-tool drilling rigs. This method of drilling consists of raising and lowering a heavy bit on the end of a steel cable that is threaded over a sheave at the top of a tower or mast. The crushed material in the bottom of the hole is mixed with water and removed by means of a bailer.
Most drilled wells in the county have galvanized-iron casing; a few have wrought-iron casing. The diameter of the casing ranges from 5 to 10 inches.
Wells in consolidated deposits--Some of the wells in the southeastern part of Jewell County obtain water from consolidated deposits (Dakota formation and Greenhorn limestone) and have been drilled with portable cable-tool rigs. Some of the wells are open-end wells; that is, the hole is cased through the overlying Carlile shale and a few feet into the consolidated rocks, but the lower part of the hole is not cased.
Wells in unconsolidated deposits--Drilled wells in the northern and northeastern parts of the county obtain water from unconsolidated Pleistocene deposits. These wells are eased the full depth of the hole to prevent caving. The casing is generally perforated in the lower part.
The Mankato public-supply wells in the White Rock Valley and the Jewell City public-supply wells are gravel-packed. In constructing this type of well, a hole of large diameter (48 to 60 inches) is first drilled and temporarily cased. A well screen or perforated casing of a smaller diameter than the hole (12 to 25 inches) 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 is filled with carefully sorted gravel--preferably of a grain size just slightly larger than the openings in the screen and also just slightly larger than that of the water-bearing material. The outer casing is then withdrawn to uncover the screen and allow the water to flow through the gravel packing from the water-bearing material. The envelope of selected gravel that surrounds the screen increases the effective diameter of the well and, hence, slightly increases the yield of the well.
Ground water in Jewell County is used chiefly for domestic, stock, and public supplies. Some water is used from the public supplies by the railroads and industrial plants in the county, but the amount is very small. No agricultural crops are irrigated with ground water. Records of 258 wells in the county and 1 outside the county were obtained and are tabulated in Table 17.
Domestic and Stock Supplies
In Jewell County, domestic supplies are obtained from wells and cisterns; stock supplies are obtained from wells and ponds. Many wells do not furnish adequate water supplies for domestic and stock purposes, especially during dry years, and must be supplemented by cisterns and ponds. Also, much of the water is very hard and is unsuitable for domestic purposes. Many dug wells are in poor condition and may be contaminated easily. A large majority of the farms have cisterns, and most rural schools use cisterns for their water supply.
Dug wells are preferred for stock wells as they are pumped intermittently and between pumping periods they serve to accumulate and store water. A large-diameter dug well will hold enough water to supply the needs of a few head of stock, and the supply generally is replenished in time for the next pumping period.
The topography of Jewell County is well adapted for the construction of ponds. Many farmers use farm ponds to furnish stock water and to recharge ground water. Most wells are in the valleys and gullies, and if down gradient from ponds receive considerable recharge from the ponds. The construction of farm ponds was greatly encouraged during the drought by many Federal and State agencies.
Drought Emergency Supplies
Jewell County was extremely hard hit by the droughts in 1934, 1936, and 1939. Stock ponds and wells failed in many instances. Farmers were compelled to haul water long distances or dispose of their livestock. The use of water was drastically restricted in most towns, especially Mankato, Jewell City, and Formoso. The Kansas Emergency Relief Committee was organized and placed under the direction of Ogden S. Jones. The committee's action resulted in the construction of ponds and community wells in the most distressed areas. Twenty-two community wells were constructed in Jewell County. They were dug in the alluvium of small valleys. A typewritten report prepared at the completion of the work contained some data on the fluctuations of the water table, logs of test holes, and descriptions of the wells that were constructed.
A committee was appointed by the Governor in December 1939 to investigate the water problems of the State and to recommend emergency measures to combat drought conditions. Among the many suggestions that were made by the committee is the following (Knapp and others, 1940, p. 10).
It would be a wise precaution to dig several drought emergency wells on each farm. These wells should not necessarily be located near the improvements but low in the farm's drainage where water may best be expected. These wells could be dug and walled after the harvest season and would repay the labor manyfold in times of water shortage. It would not be advisable to pump these emergency wells except during drought periods because pumping during normal seasons might exhaust a supply which should be held for emergencies.
Two or more wells on each farm during years of below normal precipitation may be desirable, especially on farms where the water-bearing materials have very low permeability. The removal of small quantities of water creates a cone of depression. Continued pumping expands the cone of depression. As the cone of depression expands, the hydraulic gradient decreases and the water percolates into the well at a progressively slower rate until the yield of the well becomes so small that it will not furnish an adequate water supply for the needs of the farm. Another well, possibly 1,000 feet away and practically beyond the limits of the cone of depression, may then be pumped. The water level in the well in which pumping has been temporarily discontinued will gradually return to, or nearly to, its original level. By alternating the periods of pumping of two or more wells, many farmers who heretofore have depended on the meager supplies from one well can have an adequate supply of water during years of nearly normal precipitation.
During a period of several years of below-normal precipitation, the water table declines progressively. Available information indicates that the water table in Jewell County had a net decline of more than 10 feet from 1920 to 1939. In small areas the water table disappeared, and in large areas the wells were nearly dry. However, even during the driest years, there were scattered local areas where ground water was available in sufficient quantities to supply the needs of most farmers. The community-well program that was begun in 1934 may be the solution to which the farmers must resort for their water supply during similar emergencies in the future.
Six towns in Jewell County have public water supplies--Burr Oak, Esbon, Formoso, Jewell City, Mankato, and Randall. All are supplied from wells.
Burr Oak--Burr Oak receives its water supply from two wells (2-9-23bb and 2-9-23bc, Table 17), one dug and one bored, in the alluvium of White Rock Creek. The dug well, which is about 60 feet deep and 18 feet in diameter, was dug in 1912 and was the source of supply until the other well was added in 1936. It is equipped with a turbine pump rated at 250 gallons a minute and operated by a 12-horsepower electric motor. According to S. E. Colvin, city water superintendent, it can be pumped dry in 4 hours. The bored well, which is 2 blocks north of the dug well, has a depth of 62 feet and a diameter of 15 inches. It is equipped with a plunger-type pump rated at 25 gallons a minute. It has a drawdown of 3 feet when pumping at 25 gallons a minute. The static water level in both wells is about 28 feet below the land surface. Average daily consumption is about 20,000 gallons and maximum consumption about 50,000 gallons. The railroad obtains about 3,000 gallons semiweekly. Although the water is hard, it is satisfactory for all ordinary uses.
Esbon--Esbon receives its water supply from four wells (2-10-15dd1, 2-10-15dd2, 2-10-34da, and 3-10-3da). Well 2-10-34da, which is 1 mile north of town, was dug to a depth of 60 feet and a diameter of 8 feet in 1918. This well receives its water supply from Quaternary limestone gravel. It is equipped with a 3-cylinder pump, operated by a 25-horsepower electric motor, which pumps about 1,500 gallons daily. Well 3-10-3da, in Esbon, was dug in 1924 and has a depth of 42 feet and a diameter of 8 feet. It obtains its water supply from Quaternary limestone gravel. It is equipped with a turbine pump rated at 60 gallons a minute operated by a 7-horsepower electric motor. This well has about 27 feet of water and is kept in reserve for fire protection. Wells 2-10-15dd1 and 2-10-15dd2 are bored wells that penetrate the alluvium of White Rock Creek. Well 2-10-15dd1, which was completed in 1925, has a depth of 66 feet and a diameter of 8 inches. It is equipped with a cylinder pump rated at 7 gallons a minute and operated by a 10-horsepower gasoline engine. Well 2-10-15dd2, completed in 1939, has a depth of 66 feet and a diameter of 8 inches. It is equipped with a 6-gallon a minute cylinder pump operated by a gasoline engine. The static water level in wells 2-10-15dd1 and 2-10-15dd2 is about 34 feet below the land surface. Average daily consumption is about 5,000 gallons and maximum consumption about 20,000 gallons.
Formoso--Formoso is supplied by two wells (3-6-21bd1 and 3-6-21ca2) that obtain water from Quaternary limestone gravel on top of the Fairport chalky shale member. Well 3-6-21ca2, dug in 1931 in the southwest comer of town, is 49 feet in depth and 12 feet in diameter. It is equipped with a cylinder pump rated at 90 gallons a minute and operated with a 7.5-horsepower electric motor. This well yields about 1,000 gallons of water a day. Well 3-6-21bd1, which is north of well 3-6-21ca2, was dug to a depth of 51.5 feet and a diameter of 14 feet in 1935. It is equipped with a cylinder pump rated at 25 gallons a minute and operated by an electric motor rated at 3 horsepower. This well yields about 2,000 gallons a day. Formoso has experienced serious difficulties in obtaining an adequate water supply. The available water supply has averaged about 2,500 gallons a day, which is an average of only about 10 gallons per person.
Jewell City--At the time of the investigation in 1941 the water supply for Jewell City was obtained from six wells (4-7-30ad, 4-7-30da1, 4-7-30da2, 4-7-30dd, 4-8-25da, and 4-8-25dd). These wells received their supply from limestone gravel in the valley of Buffalo Creek. The limestone gravel overlies the Fairport chalky shale member of the Carlile shale. Wells 4-8-25da and 4-8-25dd are dug wells on the west side of town. Well 4-8-25dd is near the dam on Buffalo Creek; well 4-8-25da is about half a mile north of the filtration plant. Wells 4-7-30ad, 4-7-30da1, 4-7-30da2, and 4-7-30dd, drilled wells east of town, have a depth of about 47 feet. They are equipped with cylinder pumps and operated with electric motors. The wells had yields ranging from about 2 to 10 gallons a minute. During some of the drought years, the wells failed to furnish an adequate water supply and the use of water was restricted.
Since 1941, two wells have been drilled in the SE sec. 25, T. 4 R. 8 W. (wells 4-8-25da2 and 4-8-25db). Wells 4-8-25da2 and 4-8-25db have yields of 14 and 10 gallons a minute respectively. The water supply is now obtained from the four wells on the west side of town. The four wells on the east side are maintained only as an emergency supply.
According to Carl Carlton, water superintendent, the maximum daily consumption is about 68,000 gallons and the average is about 40,000 gallons.
Mankato--The water supply of Mankato is obtained from nine wells. Wells 3-8-16ca, 3-8-22bc, and 3-8-22ca1 are dug wells in the city limits. Well 3-8-16ca is on the west side of town and is just below an impounding reservoir, well 3-8-22bc is near the Missouri-Pacific Railway depot in the southwest part of town, and well 3-8-22ca1 is in the south part of town. These wells obtain their water supply from the alluvium of a branch of Buffalo Creek. The water-bearing material consists chiefly of the limestone gravel that overlies the Smoky Hill chalk member. Six wells are in White Rock Creek valley about 8 miles north of town. Wells 2-8-11ca1, 2-8-11ca2, and 2-8-11cd2 were drilled in 1929; wells 2-8-11db1, 2-8-11db2, and 2-8-11cd1 were drilled in 1934. They range in depth from about 73 to 78 feet and yield from 5 to 15 gallons a minute. Maximum consumption of water is about 100,000 gallons a day. Mankato had considerable difficulty in obtaining an adequate water supply during some of the dry years. In 1927 they sought to obtain a deep water supply by drilling 1,200 feet into the Dakota formation, but the water was too salty for domestic use.
Randall--The water supply of Randall is obtained from a well dug in 1928 in the alluvium of Buffalo Creek. The well, in the south part of town, has a depth of approximately 40 feet and a diameter of 16 feet. It is equipped with a turbine pump rated at 50 gallons a minute and operated by an electric motor rated at 73 1/2 horsepower. Average daily consumption is about 10,000 gallons and maximum about 15,000 gallons.
Possibilities of Developing Additional Supplies
Studies of the pumpage records from wells and the pumping tests that were made in Jewell County indicate that the greater part of the yield from a well is derived from storage in the immediate vicinity of the well. Also, water-table contour maps indicate that the pumping affects appreciably only those contours comparatively near the pumped well, even though the continuous pumping in the well field exceeds the amount of underflow moving into the pumped area. The water comes from the cone of depression, and as pumping continues the cone enlarges and the yield of the well diminishes. Unless recharge occurs periodically, the yield continues to diminish.
During the dry years between 1930 and 1940, many of the wells in Jewell County failed. Some of them failed because of a large decline of the water table; in some places the water table disappeared. Other wells failed because of the development of a large cone of depression and lack of periodical recharge. When wells fail because of the decline or disappearance of the water table, the development of additional supplies is difficult, if not impossible. The only immediate solution is to haul water. A long-range solution may be (1) the construction of reservoirs to furnish water for stock use and to recharge the ground water down gradient from the reservoir; (2) the adoption of farming practices that will increase infiltration and, under favorable conditions, increase groundwater recharge; and (3) a greater development of community wells. When wells fail because of the development of large cones of depression, the obvious solution is to obtain the water supply from a larger number of wells spread over a larger area. Some of the towns in Jewell County that have experienced considerable difficulty in obtaining an adequate water supply might consider the development of a water supply based on a system of several wells of low cost and low yield instead of trying to develop an adequate water supply from only two or three wells.
There will generally be some doubt whether a municipal well has failed because of a general decline of the water table or whether the failure was caused by the development of a large cone of depression. The cause of failure can be determined easily if a few properly distributed wells in the area, some of which are outside the cone of influence caused by pumping, are measured periodically for several years. The records of a few observation wells will save much time and expense in an investigation when additional water supplies must be developed.
Chemical Character of Ground Water
The chemical character of the well waters in Jewell County is shown by the analyses of water from 36 representative wells given in Table 15. The samples of water were analyzed by H. A. Stoltenberg, Chemist, in the Water and Sewage Laboratory of the Kansas State Board of Health. The analyses show only the dissolved mineral content of the waters and do not, in general, indicate the sanitary condition of the waters.
Table 15--Analyses of water from typical wells in Jewell County Analyzed by H. A. Stoltenberg. Dissolved constituents given in parts per million. One part per million is equivalent to one pound of substance per million pounds of water or 8.33 pounds per million gallons of water.
|Well number||Depth (feet)||Geologic source||Date of
|Hardness as CaCO3|
Chemical Constituents in Relation to Use
The following discussion of the chemical constituents of ground water has been adapted from publications of the U. S. Geological Survey and the State Geological Survey of Kansas.
Dissolved solids--The residue left after a natural water has evaporated consists of rock material, probably some organic material, and a small amount of water of crystallization. Water containing less than 500 parts per million of dissolved solids generally is satisfactory for domestic use, except for the difficulties resulting from its hardness, and in some areas, from excessive iron content and corrosiveness to iron pipes and fixtures. Water having more than 1,000 parts per million of dissolved solids is likely to contain enough of certain constituents to produce a noticeable taste or to make the water unsuitable in some other respects.
The dissolved solids in samples of water collected in Jewell County ranged from 101 to 3,880 parts per million. Three samples had less than 300 parts per million; nine samples had more than 1,000 parts per million (Table 16).
Hardness--The hardness of water, which is the property that receives the most attention generally, is most commonly recognized by its effect when soap is used with the water. Calcium and magnesium cause almost all the hardness of natural water. These constituents are also the active agents in the formation of the greater part of the scale formed in steam boilers and in other vessels in which water is heated or evaporated.
Table 16--Summary of the chemical quality of the samples of water from wells in Jewell County.
|Range in parts
|Less than 300||3|
|More than 2,000||6|
|Less than 100||2|
|More than 1,000||7|
|Less than 10||13|
|More than 500||2|
In addition to total hardness, the table of analyses shows the carbonate hardness and the noncarbonate hardness. The carbonate or "temporary" hardness is that due to the presence of calcium and magnesium bicarbonates. It can be almost entirely removed by boiling. The noncarbonate hardness is due to the presence of sulfates or chlorides of calcium and magnesium, but it cannot be removed by boiling and has sometimes been called permanent hardness. With reference to use with soaps, there is no difference between carbonate and noncarbonate hardness. In general, the noncarbonate hardness forms harder scale in steam boilers.
Water having a hardness of less than 50 parts per million is generally rated as soft, and its treatment for reduction of hardness under ordinary circumstances is not necessary. Hardness between 50 to 150 parts per million does not seriously interfere with the use of water for most purposes, but it does slightly increase the consumption of soap, and its removal by a softening process is profitable for laundries or other industries using large quantities of soap. Water in the upper part of this range of hardness will cause considerable scale in steam boilers. Hardness exceeding 150 parts per million can be noticed by anyone, and if the hardness is 200 or 300 parts per million it is common practice to soften water for household use or to install a cistern to collect soft rain water. Where municipal water supplies are softened, an attempt is generally made to reduce the hardness to from 60 to 100 parts per million. The additional improvement from further softening of a whole public supply generally is not deemed worth the increase in cost.
The hardness of the samples of water from Jewell County ranged from 68 to 2,320 parts per million (Table 16).
Iron--Next to hardness, iron is the constituent of natural water that in general receives the most attention. The quantity of iron in ground water may differ greatly from place to place even though the water is from the same formation. If water contains much more than 0.1 part per million of iron, the excess will normally precipitate and settle as a reddish sediment. Iron in sufficient quantity to give a disagreeable taste and to stain clothing and utensils may be removed from most waters by aeration and filtration, but some water requires the addition of lime or further treatment.
Of 36 samples of water from Jewell County, 34 contained 0.1 part per million or more of iron. Five samples of water had more than 5 parts per million of iron.
Fluoride--Although fluoride generally is present only in small quantities in ground water, the amount of fluoride present in water used by children should be known. Fluoride in water has been shown to be associated with the dental defect known as mottled enamel, which may appear on the teeth of children who drink water containing too much fluoride during the formation of the permanent teeth. Dean (1936) has described the effects of fluoride in drinking water on the teeth of children (p. 1270):
. . . from the continuous use of water containing about 1 part per million, it is probable that the very mildest forms of mottled enamel may develop in about 10 per cent of the group. In water containing 1.7 or 1.8 parts per million, the incidence may be expected to rise 40 or 50 per cent, although the percentage distribution of severity would be largely of the "very mild" and "mild" types. At 2.5 parts per million an incidence of about 75 to 80 per cent might be expected, with possibly 20 to 25 per cent of all cases falling into the "moderate" or severer type. A scattering few may show the "moderately severe" type.
At 4 parts per million the incidence is, in general, in the neighborhood of 90 per cent, and as a rule, 35 per cent or more of the children are classified as "moderate" or worse. In concentrations of 6 parts per million or higher an incidence of 100 per cent is not unusual.
Recent studies have indicated that, although more than 1.5 parts per million of fluoride may be detrimental to the teeth of children by causing mottling, less than 1.5 parts is beneficial in helping to prevent tooth decay (Dean, Arnold, and Elvove, 1942).
None of the samples of water collected in Jewell County contained more than 0.9 part per million of fluoride. Of the 36 samples of water, 31 had 0.5 part per million or less.
Nitrate--The nitrate content of water used for drinking has been the object of a great deal of attention in the past few years since the discovery that high nitrate water may cause cyanosis of infants when the water is used in the preparation of baby formulas. Although some nitrate is derived from nitrate-bearing rocks and minerals in the water-bearing formations, high nitrate concentrations are probably due largely to direct flow of surface water into the well or to percolation of nitrate-bearing water into the well through the top few feet of the well. Nitrate compounds are readily dissolved from soils that have high concentrations of these salts. Other sources of nitrogenous material are privies, cesspools, and barnyards; consequently, a large amount of nitrate may indicate also that harmful bacteria are present in the water. Because they generally are poorly sealed, dug wells allow more contamination by surface seepage than drilled wells, which are commonly deeper and more tightly cased.
Ninety parts per million of nitrate as NO3 in water is considered by the Kansas State Board of Health as dangerous to infants, and some authorities advocate that water containing more than 45 parts per million (as NO3) should not be used for formula preparation (Metzler and Stoltenberg, 1950). Of the 36 samples of water collected from wells in Jewell County, 9 samples contained more than 50 parts per million of nitrate, 5 contained more than 200 parts, and 2 contained more than 500 parts (Table 16).
The analyses of water given in Table 15 show only the amounts of dissolved mineral matter in the water and do not indicate the sanitary quality of the water.
The entire population of Jewell County is dependent on water supplies from wells, and it rests chiefly with the drillers and individual well owners to observe precautions to insure a safe and wholesome water supply. Every precaution should be used to protect domestic and public water supplies from pollution by organic material. A well should not be located where there are possible sources of pollution. The drainage from cesspools and privies is particularly dangerous. Every well should be constructed to seal off all surface water, especially dug wells because they are more subject to contamination from surface water.
Kansas Geological Survey, Geology
Placed on web Nov. 21, 2008; originally published Oct. 1955.
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