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The growth of population in our suburbs and rural areas introduces many water supply problems likely to affect the public health. All health officials agree that public water supplies are the most reliable and should be used in preference to individual wells. However, many people must rely on wells until a public water supply is available. In New York State, outside New York City, more than 2,500,000 people depend on individual well-water supplies, not counting the vacationing and traveling public.
This booklet has been prepared to help you build a satisfactory ground water supply that is properly located, constructed and protected. It is of particular value to well drillers, building and plumbing contractors, architects and engineers. It also helps owners of homes, dairy farms, milk plants, camps, recreation areas, restaurants, rural schools, granges and resorts who plan to have work done or to make repairs themselves. The principles given here represent widely accepted good practice.
Because of variation in local conditions, you should consult your local health department or state district health office.
We hope that this material will help promote better well construction and assist in removing known causes of water supply contamination.
New developments in health department programs have brought out the need for a statewide booklet to obtain as much uniformity as possible in water well location, construction and protection. The cooperation and assistance of many persons, including the sanitary engineers and sanitarians in city and county health departments, in state district health offices and in the central office were generously given and are gratefully acknowledged.
The use of names of products or manufacturers in this booklet are intended to obtain better understanding and does not imply endorsement by the New York State Department of Health.
Where a public water supply is available, an owner should make every effort to use it in preference to any other. Public water supplies are usually under competent management and routine health department supervision.
In the absence of a public water supply, a well can normally be relied on to produce water of satisfactory sanitary quality if the well is properly located, constructed and protected. If fundamental precautions are not taken, or if an area becomes heavily populated, contamination of the water supply is probable.
Figure 1 shows geological formations and ground water sources in New York State. Figure 2 illustrates a geologic section and ground water terms. Depth and yield of selected wells in the state, and their chemical quality, are given in Table 1.
Water quality. To be of good sanitary quality, water must be safe to drink, clear and palatable. It should contain no significant amounts of objectionable chemicals. The Public Health Service Drinking Water Standards, 1962, and New York State Health Department Administrative Rules and Regulations, Part 72 (Appendix A) give drinking water standards. Special water quality problems are reviewed on pages 47 and 50.
Water quantity. Tables 2 and 4 show the water needs for different uses and types of establishments. The capacity of a water source depends on the area's average rainfall and the characteristics of its geological formation. The cost and method used to develop the source frequently determine the amount of water which can be extracted from the ground. A well for a private dwelling should, if possible, have a minimum yield of 5 gallons per minute.
Where the water yield is limited, a larger pressure tank or a ground level or elevated storage tank may be necessary. This is discussed further on page 28. In some extreme situations it may be necessary to develop a surface water supply-a stream, lake or pond. However, surface water sources usually require elaborate treatment, including filtration and chlorination, and should not be developed without consulting the local health department.
|Type of Establishment||Gallons per day *|
|Dwellings and apartments (per bedroom)||150|
|Additional (or non-resident boarders)||10|
|Camp sites (per site)||100|
|Mobile home parks (per unit)||125-150|
|Restaurants (toilets and kitchens)||7-10|
|Without public toilet facilities||2.5 -3|
|With bar or cocktail lounge additional||2|
|Hospitals (per bed)||250-500|
|Institutions other than hospitals (per bed)||75-125|
|Places of public assembly||3-10|
|Turnpike rest areas||5|
|Turnpike service areas (10 per cent of cars passing)||15-20|
|Amusement and commercial:|
|Airports (per passenger)||3-5|
|Day workers (per shift)||15-35|
|Drive-in theaters (per car space)||5|
|Gas station (per vehicle serviced)||10|
|Milk plant, pasteurization (per 100 lbs. of milk)||11-25|
|Movie theaters (per seat)||3|
|Picnic parks with flush toilets||5-10|
|Self-service laundries (per machine)||400|
|Shopping center (per 1000 sq. ft floor area)||250|
|Stores (per toilet room)||400|
|Swimming pools and beaches with bathhouses||10|
|Livestock (per animal)|
|Poultry (per 100):|
Drilled wells for rural water supplies are generally 6 to 8 inches in diameter and 50 to 200 feet deep. When the well is constructed a hole is made in the ground. A steel or wrought-iron casing is lowered as the well is drilled to prevent the hole from caving in. The drill-hole is larger than the casing, thereby leaving an irregular space around the outside length of the casing. Unless this space or channel is closed, pollution flows down the side of the casing and into the water sources from the surface, from crevices close to the surface or from polluted formations the well penetrates. This is true of wells through clay, hardpan or rock, especially in limestone formations; these require special construction precautions described in Table 5. Water in the ground water table can move up and down this annular space when a well is pumped. The same thing can happen when an artesian well is pumped.
Contamination in a properly located drilled well usually has one of three causes: a) inadequate disinfection of the well after construction or repairs; b) failure to seal the annular space between the drill hole and the casing; or c) failure to provide a tight sanitary seal at the place where the pump line or lines pass through the casing.
Well disinfection is covered on page 42; cement grouting in Table 5, and page 31; and sanitary seals and underground connections in pages 36-41.
A drive point with screen is fastened to the well pipe and driven until water is reached, usually with a maul or a drive shoe. A reasonable yield can be obtained if the screen is driven well below the water table. This also provides greater protection from pollution.
A minimum driven well diameter of 2 inches is recommended, constructed as shown in Figure 3 and as explained in Table 5 where feasible. The well can be driven quickly and at little cost.
Since dug wells are relatively wide they have a large storage capacity. But because the water level lowers during drought, they are often unreliable, especially where modern plumbing is used. Being relatively shallow, they are more liable to surface water pollution.
In areas where drilled wells yield unsatisfactory water or very little of it, an owner may have to rely on a properly developed dug well.
It is often difficult to find the true source of a spring. When spring basins are not constructed over the true source, the yield is limited and pollution is common, no matter how well the spring basin itself is constructed.
Springs in limestone introduce major hazards because limestone is characteristically channeled and fractured, and pollution can travel long distances without being purified. Bacteriological sampling of the water reveals pollution at the time of sampling, but continuous sampling is impractical. Limestone spring supplies are dangerous; even chlorination may not counteract heavy doses of pollution. Drilled well supplies are preferable.
Some cisterns have filters to remove dust, dirt and bird droppings washed off the roof. In any case, if the water is available at a tap for drinking, the cistern must be disinfected after each rain (Page 46). The cistern needs a tight and rodent-proof cover. If it is underground it should be at a higher level and at least 50 feet from any sewer and 100 feet from any sewage leaching system. The health department has details on constructing cisterns and filters. Cistern supplies should not connect to the regular drinking water supply.
Figure 6 shows a typical lot layout for a well and septic tank system. Table 3 gives suggested minimum distances between water and sewerage units, although under certain circumstances the health department may require or permit variations.
One cannot generalize and say with certainty how far away a sewage disposal system must be, or through what depth of soil or distance sewage must pass to be purified. Organic pollution travels a short distance through fine sand, silt or clay; but will travel indefinite distances through coarse gravel, fissured rock, dried-out cracked clay, or solution channels in limestone.
The safe distance between a well and a sewage disposal system is dependent upon many variables, including the hydrology and geology of the area and chemical, physical and biological processes. In general, wells (and springs) should not be in an area subject to flooding. They should be uphill from any privy, barnyard, cesspool, tile field, leaching pit or other sewage disposal system and located with consideration to the factors noted below.
A sewage disposal system in a soil layer about 5 feet deep over creviced or fractured rock should be at a greater distance from a well than one in a soil layer 20 feet deep over rock. The slope of visible rock outcrops will also indicate the direction of flow of soil water and hence pollution with respect to the well location. If rock or clay lies at a shallow depth between the earth overburden and waterbearing formation, then sealing of the well casing with cement grout becomes more important than the separating distance from sources of pollution.
When pumping from a well, the direction of ground water flow around the well will be toward it. Since the pumping level of water in the well will probably be 50 to 150 feet more or less below the ground surface, it will exert an attractive influence on ground water perhaps as far as 500 to 1000 feet away from the well, regardless of the elevation of the top of the well. In other words, distances and elevations of sewage disposal systems must be considered relative to the elevation of the water level in the well while it is being pumped. A sewage disposal system 100 feet away on level ground or down grade from a well may still be 50 feet higher than the water level in the well.
It must be remembered that well construction is a very specialized field. Most well drillers want to do a proper job for they know that a good well is their best advertisement. However, in the absence of a state law on well construction (except on Long Island) and without licensing of well drillers, price frequently determines the type of well that is built.
A well drilled on a plot in a subdivision must conform with the requirements shown on the health department approved plan, and wells drilled to serve public places must produce water that meets health department standards. Also, some local health departments have specific regulations about well construction on individual plots. See Appendix B.
Figures 3-5, 9-15 show principles of proper well (and spring) development and construction, and Table 5 gives additional details.
A hydropneumatic pressure tank makes available only 10 to 20 per cent of tile tank's volume and helps to meet peak demands for water. Table 4 shows suggested tank capacities for private homes. Sometimes a larger pressure tank or a storage tank is installed; but a gravity storage tank requires double pumping unless it is elevated.
In general the well itself gives the most practical water storage for a private home if the casing is large enough. A 6-inch casing holds 2 1/4 times as much water as a 4-inch casing; 1.47 gallons per foot of depth, compared with 0.652 gallons. (Appendix C.) Yet a 6-inch casing costs little more per foot. In view of limited well yield, no well in New York State should be less than 6 inches in diameter, except as noted in Table 5.
Well casing. Drilled wells must be cased to a proper depth (Table 5) to keep dirt and stones from falling in, to prevent surface water or water close to the surface from flowing directly into the well, and to seal off water from undesirable formations. Only water-well casing of clean steel or wrought-iron should be used. (Appendix C). Used pipe is not satisfactory. Standards for well casing are given in the American Water Work Association publication AWWA Standard for Deep Wells, AWWA A100-58.
A contaminated well supply causes the home owner considerable inconvenience and extra expense for it is difficult to seal off contamination after the well is drilled. In some cases the only practical answer is to build a new well.
Proper cement grouting of the space between the drill hole and well casing where the overburden over the water bearing formation is clay, hardpan or rock c an prevent this common cause of contamination (Figure 3, Table 5 and pages 37, 44).
There are many ways to seal well casings. The best material is neat cement grout. But to be effective the grout must be properly prepared (a proper mixture is 5 1/2 gallons of clean water to a bag of cement), poured or pumped as one continuous mass, and placed upward from the bottom of the space to be grouted. See Appendix D.
The clear annular space around the outside of the casing and the drill hole must be at least 1 1/2 inches on all sides to prevent bridging of the grout. Driving the easing, or installing a lead packer, a rubber sleeve or a similar device, does not provide a reliable annular space seal.
Cement grouting of a well casing its entire length of 50 to 100 feet or more (Table 5) is good practice but expensive for the average farm or rural dwelling. An alternative is grouting to at least 20 feet below ground level. This provides adequate protection for most installations, except in limestone formations (Table 5). It also protects the casing from corrosion.
For a 6-inch diameter well a 10-inch hole is drilled, if 6-inch welded pipe is used, to at least 20 feet, or to solid rock if the rock is deeper than 20 feet (Table 5). If 6-inch coupled pipe is used a 12-inch hole will be required. From this depth, the 6-inch hole is drilled until it reaches a satisfactory water supply. A temporary outer casing, carried down to rock, prevents cave-in until the cement grout is placed.
Upon completion of the well the annular space between the 6-inch easing and temporary casing or drill hole is filled from the bottom up to the grade with cement grout. The temporary pipe is withdrawn as the cement grout is placed-it is not practical to pull the easing after all the grout is placed.
The extra cost of the temporary casing and larger drill hole is small compared to the protection obtained. The casing can be reused as often as needed. In view of this, well drillers who are not equipped should consider adding larger casing and equipment to their apparatus. temporary casing or larger drill hole and cement grouting are not required where the entire earth overburden is 40 feet or more of silt or sand and gravel, which immediately close in on the total length of casing to form a seal around the casing; however, this condition is not common.
Drilled wells serving public places are usually constructed and cement-grouted as explained in Table 5.
Well drillers and owners of private wells are urged to discuss special problems with their health department. Thus any question can be discussed in detail to find a practical solution in the best interest of the owner.
When the top of the casing is buried, the well cannot be readily inspected, disinfected or repaired. A proper sanitary survey cannot be made since the well location is indefinite, nor its construction checked for possible sources of pollution. Water samples from buried wells are of limited value unless taken during each season of the year for at least one year and annually thereafter. When contamination is reported, a survey to determine the cause (page 43), and extension of the well casing as noted below is indicated.
Regardless of the method used to extend the well casing above ground, it is necessary to provide a sanitary well seal as explained below. The well should then be disinfected as explained on page 42.
Buried lines between the well and pump, if they are not under pressure, should pass through a water-tight conduit (Figure 14).
If the earth overburden over the bedrock is less than 10 to 20 feet, the water entering the well will probably be polluted. Drilling the well deeper into non-water bearing bedrock would provide storage but little, if any, additional water. The annular space around the outside of the casing should be carefully sealed (Appendix D) by means of cement grout from the ground surface down to within 1 to 2 feet of the bottom of the casing at bedrock, unless a sand, silt or sand and gravel is penetrated. This will at least prevent the direct entrance of pollution from the surface into the well. If a public water supply is not available, and such water must be used, continuous chlorination should be provided unless bacteriological examinations of a series of 3 or more samples of water, collected at different seasons of the year indicate otherwise.
If the earth overburden over the non-water bearing rock is greater than 20 to 40 feet, the chances for a satisfactory well are greatly improved. Drilling the well into the bedrock would provide additional water storage. As stated above, the annular space around the outside of the casing should be carefully sealed (Appendix D) by means of cement grout, from the ground surface down to within 1 to 2 feet of the bottom of the casing at bed rock, unless a self-sealing sand, silt or sand and gravel is penetrated. The annular space at the bottom 1 to 2 feet of the casing could be filled to advantage with clean, chlorine disinfected, sand and fine gravel.
It must be emphasized that the procedures described under this heading should be considered only where non-water bearing bedrock is encountered and where the alternative is the development of another water supply, or to have no water if recommended well construction practice is followed. In good well construction the casing is cement grouted and sealed in rock. In any case, shallow wells terminating in non-water bearing bedrock are more likely to be affected by drought.
The two situations described above would dictate that public water supply and/or sewers be provided. Where this is not possible sewage disposal should be by means of a septic tank-tile field leaching system located as far as possible, 100 feet or more, and downgrade from the well as explained in Table 3 and page 23.
After a well is constructed and pumped clear, or after any improvements are made, it should be disinfected with a chlorine bleach. Bleaches containing 5.25 per cent available chlorine are sold in supermarkets and grocery stores under such names as Clorox, Dazzle, Purex, White Sail, 101, etc. Here is the procedure for disinfecting a well:
1) Mix 2 quarts of bleach in 10 gallons of water. Pour the solution into the well while is it being pumped. Keep pumping until the chlorine odor appears at all taps. Re-circulate the water back into the well for at least an hour. Then close the tap and stop the pump.
2) Mix 2 more quarts of bleach in 10 gallons of water and pour this solution into the well. Allow the well to stand idle for at least 8 hours and preferably 12 to 24 hours.
3) Pump the well to waste, away from grass and shrubbery, through the storage tank and taps, such as an outside connection, until the odor of chlorine disappears. The chlorine may persist for 7 to 10 days depending on how much water is used.
After all the chlorine is pumped out, a water sample should be collected and tested by the Health Department, if this service is available, to determine whether all contamination has been eliminated. If the Health Department does not examine samples from private water supplies, a will have to be used and prior arrangements made to pick up a sterile sample bottle and sampling instructions. Make sure all chlorine has been pumped out of the well (no chlorine taste or odor in the water) before a sample is collected.
Proper disinfection of flowing wells or springs requires special treatment, which the Health Department will explain in specific instances.
Remember that disinfection is no assurance that water entering the well or spring is free of pollution.
[1. Chlorine is toxic. Obey all safety precautions.
2. Bleach sold in supermarkets may not be Food Grade. Public Water Systems must use NSF approved chemicals.]
A well owner must be alert for any change in the appearance or taste of the water, for this indicates possible contamination. Sometimes the laboratory examination of a water sample reveals bacteriological contamination.
Under any of these conditions, all water used for drinking or food processing and cooking should first be boiled or disinfected or treated as approved by the health department, until the cause of the change in quality or contamination is found and removed. Where a public water supply becomes available, it should be used, and the polluted well filled in (Consult AWWA standard A100 for directions) or the water made inaccessible. If a new well is drilled, it should be located, constructed and protected as explained in this booklet.
Polluted surface water or superficial ground water immediately around the well can also enter the well through holes in the side of the casing, channels along the length of the casing, or crevices in the rock leading to the well. Sometimes the casing is loose or is only a few feet long. An inspection should be made of the top and inside the casing, using a mirror or strong light, to determine if water is entering the well from close to the surface or through the bottom of the casing.
A dye or salt solution, or even plain water, poured around the casing can help reveal the source of pollution. A chemical examination may be needed to show the change in the chlorides or the presence of dye in the water if the salt cannot be tested nor the dye seen.
If the casing is found to be tight, it is assumed that pollution is finding its way into the water-bearing stratum through sewage saturated soil or creviced rock or channeled rock (limestone) at a greater depth. Sometimes the polluted stratum can be sealed off and if necessary the well drilled deeper. But there is no guarantee of water or that the new formation will not become polluted later. Check the cost and advisability for doing this with a competent well driller and a geologist.
Once a stratum is contaminated with sewage, it is very difficult to prevent future pollution of the well unless all water from such a stratum is effectively sealed off. Moving the offending sewage disposal system to a safe distance is possible, but evidence of the pollution may persist for some time. The same general principles apply to dug and driven wells.
In an emergency, contaminated well water or surface water can be made satisfactory for drinking by boiling or by chemical disinfection. The water should be as clear as possible; let muddy or cloudy water settle, then pour off the clear water into a separate container. Filtering the water through a clean cloth or milk strainer may help.
When heat or fuel is available, the safest way to make a small volume of water satisfactory for drinking is to boil it for at least two minutes. The water should then be cooled and stored in a clean protected container.
Chemical disinfection of clear water is summarized below. If the water is turbid or colored, double the amount of disinfectant.
|Disinfectant||Drops per Gallon of Water||Quarts per 1,000 Gallons|
|1% Chlorine solution||40||2|
|2.5% Chlorine solution||16||1|
|5.25% Chlorine solution||8||1/2|
|2% Tincture of iodine||20||...|
Hard water makes it difficult to produce suds or to rinse laundry, dishes or milk equipment. Water hardness is caused by dissolved calcium and magnesium bicarbonates, sulfates and chlorides. Pipes clog, and after a time equipment and water heaters become coated with a hard mineral deposit, sometimes referred to as milkstone or lime scale. A commercial zeolite or synthetic resin water softener is used to soften water. It must be replaced or regenerated periodically and disinfected with chlorine (one-fifth of the amount shown above) to remove contamination after each regeneration. Softeners do not remove contamination in the water supply. A filter should be placed ahead of a softener if the water is turbid.
Turbidity or muddiness usually occurs in water from a pond, creek or other surface source. This water is polluted and requires coagulation, filtration and chlorination treatment. Wells sometimes become cloudy from cave-in or seepage from clay or silt strata but may clear up with prolonged pumping.
Sand filters can strain out mud, dirt, leaves and foreign matter, but not bacteria or viruses. Nor are charcoal, zeolite or carbon filters suitable for this purpose, and in addition they clog. Iron and iron growths which sometimes cause turbidity in well water are discussed below.
Iron in water may cause turbidity, a bitter taste in tea or coffee, and stains on plumbing fixtures, equipment and laundry. A commercial zeolite water softener or an iron removal filter removes up to 1.5 to 2.0 parts per million iron from well water devoid of oxygen. The water softener is regenerated with salt; the iron removal filter with potassium permanganate. Controlled addition of a polyphosphate can keep the iron in solution.
With higher concentration of iron, the water is chlorinated to oxidize the iron, but the water should then be filtered before it goes to the softener to remove the iron precipitate. Raise the pH of the water to above 7.0 if the water is acid; soda ash is usually used for this purpose added together with the chlorine solution.
Another approach is to discharge the water to the air chamber of a pressure tank or to a sprinkler over a cascade above a tank. It is necessary to flush out the iron which settles in the tank and to filter out the remainder.
Injecting a chlorine solution into the water at its source, where possible, controls the growth of iron bacteria, if this is a problem.
Corrosive water dissolves metal, shortens the life of water tanks, discolors water and clogs pipes. Water can be made non-corrosive by passing it through a filter containing broken limestone or marble chips. The controlled addition of a polyphosphate, silicate or soda ash (commercial units are available) usually prevents metal from going into solution. The water remains clear and staining is prevented.
Tastes and odors. Activated carbon filters are normally used to remove undesirable tastes and odors from domestic water supplies. They do not remove contamination. Hydrogen sulfide in water can be eliminated by aeration and chlorination, followed by an activated carbon filter. The activated carbon will have to be replaced when its capacity has been exhausted. Filtration alone, through a pressure filter containing a special synthetic resin, also removes hydrogen sulfide in most cases. Use the water in question to check the effectiveness of a process before you purchase any equipment.
Detergents in water can be detected visually or by laboratory examination. When their concentration exceeds 1 part per million, foam appears in a glass of water drawn from a faucet. Detergents themselves have not been shown to be harmful, but their presence is evidence that waste water from one's own sewage disposal system or from a neighbor's system is entering the water supply source. In such circumstances, the sewage disposal system may be moved, a well constructed in a new area or the well extended into a deeper water-bearing formation not subject to pollution (page 43). There is no guarantee that the new water-bearing formation will not become polluted later. Solution of this problem is connection to a public water supply and/or to a public sewer. There is no practical way at this time to remove detergent from a water supply.
Salty water. In some parts of the state salty water may be encountered. Since the salt water generally is overlain by fresh water, the lower part of the well in the salt water zone can be sealed off. But when this is done, the yield of the well is decreased.
Sometimes, waste salt water resulting from the back-washing of a home ion exchange water softener is discharged close to the well. Since salt water is not filtered out in seeping through the soil, it may find its way into the well. The best thing to do is to discharge the waste water as far as possible and downgrade from the well. Salt water is corrosive. It will damage grass and plants. It is a soil sterilant. A practical but more expensive alternative is to utilize a commercial water softening service in which the softener is periodically replaced by a regenerated unit. This may also be indicated if the water supply is inadequate.
The sodium content of water passing through a home water softener will be increased. Individuals who are on a sodium restricted diet should advise their physician that they are using home-softened water since such water is a continual source of dietary sodium.
Gasoline or fuel oil in water. Gasoline or fuel oil may accidentally get into a well. Leaking storage tanks, overflow from tank air vents, or accidental spillage near the well may be the cause. Correction requires elimination of the cause, followed by lowering of the pump drop pipe. The gasoline or fuel oil will gradually collect on the water surface in the well and will have to be separately pumped out until all accumulation is removed. An activated carbon filter will also remove small amounts of oil or gasoline. It may become expensive if large quantities of oil or gasoline must be removed and the activated carbon replaced frequently.
Polluted water. Sometimes chlorination or ultraviolet "sterilization" units are suggested to make polluted water safe for drinking without regard to the type, amount or cause of pollution. This may be hazardous. Instead, every effort should be made to obtain water from a system meeting the standards given in this pamphlet. See also page 43. Chlorination or the ultraviolet process is acceptable only for the treatment of clean, clear water.
Ultraviolet ray lamps are not considered satisfactory for the purification of water supplies which may be subject to pollution. Examples are surface water supplies such as ponds, lakes and streams which usually vary widely in physical, chemical and biological quality, and wells or springs in which the water may contain turbidity, color, iron or organic matter. Pretreatment usually including coagulation, filtration and chlorination would be required ahead of the ultraviolet unit to remove substances which interfere with the effectiveness of the ultraviolet rays. In addition, certain controls are needed to ensure that the efficiency of the unit is not impaired by changes in light intensity, rate of water flow, condition of the lamp, turbidity of the water, temperature conditions, etc.
Similar pretreatment would be required prior to the disinfection of water which is not of good physical character when using only chlorination treatment. See page 23.
Check with your health department if you are considering the purchase of a chlorinator or ultraviolet unit.
There must be no connections between a water system carrying drinking water and a plumbing fixture, tank or sewer, soil, waste or pipeline, or any other water system whereby contaminated or polluted water may flow or be drawn into a drinking water system.
To avoid the possibility of contaminated or polluted water being drawn into or flowing into a water system, special health department approved backflow preventers or vacuum breakers are required for certain types of plumbing fixtures and connections. These include dishwashing machines, steam tables, boiler make-up water systems, pump prime lines, cattle drinking cups or stock tanks, flushometer valves, swimming pools, aspirators, industrial process water lines, tanks or vats with bottom or side-wall inlets. In some instances an air gap, surge tank or similar approved device is required instead of a backflow preventer (reduced pressure zone type) or vacuum breaker (non-pressure type).
In view of the possible health hazard, a cross-connection survey should be made periodically at places where cross-connections might be found. Consult with the health department if you need advice. Refer to Water Supply and Plumbing Cross Connections, Public Health Service Publication No. 957, Superintendent of Documents, U. S. Government Printing Office, Washington, D. C. 20402, Price 40 cents.
*See "Policy Statement on use of the Ultraviolet Process for Disinfection of Water" Department of Health, Education and Welfare, Public Health Service, April 1, 1966.
A special sanitary survey water sampling service is available to residents of some counties. On request and trained as time permits, a trained health department representative makes a sanitary survey of the area surrounding a private water supply. The owner may first be asked to complete a description form. A water sample is collected only if the well or spring is properly located, developed and protected. water samples from an unsatisfactory source can not give reliable information. The owner of a home camp farm or
business establishment wants to know that his water supply is always safe to drink. and the health department wants to give him this assurance. If weaknesses are apparent at the time of the survey, a sample is not collected, but pertinent recommendations are made. After needed improvements are made and the well disinfected (page 42), a water sample can be collected and interpreted for the home-owner.
Water samples are examined in a laboratory approved by the State Health Department. The examination includes tests for the presence of coliform group of organisms which are found in a large number in the intestinal tract of all warm-blooded animals. One milliliter of sewage has 4 to 5 million of these bacteria; hence the presence of coliform bacteria in the drinking water is positive evidence of pollution and possibly of disease-causing germs. Satisfactory reports on samples collected over a period of years gives assurance of water safety. Any change in the appearance or taste of the water is cause for immediate concern (page 43).
If the local health department is not staffed or equipped to examine private water supplies, the well owner will have to use a commercial laboratory and make prior arrangements to pick up a sterile sample bottle and sampling instructions. However, before collecting a sample, make a sanitary survey of the well and its surroundings; make sure the well is properly located, constructed and protected ; have any needed repairs done and the well disinfected before collecting a sample. Make sure all chlorine has been pumped out before a sample is collected, for otherwise the laboratory examination would be worthless.
The solution of special or more difficult rural water supply problems may not be found in this pamphlet. Health department sanitary engineers and sanitarians will help with these or provide guidance wherever possible.
|Test (2,3)||MCL (5,6)|
|Coliform bacteria||Any positive result is unsatisfactory|
|Lead||.015 mg/l (15 µg/l)|
|Nitrates||10 mg/l as N|
|Nitrites||1 mg/l as N|
|Iron plus manganese||0.5 mg/l|
|Sodium||No designated limit. (1)|
|pH||No designated limit.|
|Hardness||No designated limit.|
|Alkalinity||No designated limit.|
|Turbidity||5 NTU (4)|
(1) Water containing more than 20 mg/l of sodium should not be used for drinking by people on severely restricted sodium diets. Water containing more than 270 mg/l of sodium should not be used for drinking by people on moderately restricted sodium diets.
(2) Additional tests are recommended for (a) petroleum products and/or solvents if a well is located in the vicinity of an oil storage facility or a gasoline station, (b) hazardous substance list metals, PCBs, and pesticides if a well is located near a landfill without monitoring wells/data, and (c) specific chemicals used if a well is located near an industry using chemicals without monitoring wells/data.
(3) All sample analyses should be conducted and reported by an environmental laboratory for drinking water approved by the NYS Health Department, Wadsworth Center, Division of Environmental Sciences.
(4) NTU means Nephelometric Turbidity Units
(5) mg/l means milligrams per liter
(6) µg/l means micrograms per liter
Part 72 was repealed June 14, 1977. Please refer to Subpart 5-1 of the State Sanitary Code for maximum contaminant levels allowed for public water supply systems in addition to those listed above.
Water wells shall be of such materials and located, constructed, developed. and protected as described in this bulletin and in accordance with good well drilling practice.
a. The well shall be constructed in an accessible location which is not subject to flooding, and at a distance, from potential sources of pollution on the owner's property or on adjoining properties, which is not less than that stated in Table 3 of this bulletin.
b. When a well is located adjacent to a building, it shall be so located that the center line of the well, extended vertically, will clear any projection from the building by not less than five feet. The top of the well casing shall be readily accessible.
The well shall be developed from a water-bearing formation at a depth greater than 20 feet below the ground surface.
a. The well casing shall be new wrought iron or steel well casing pipe which complies with ASA Standard B36.10-1959 or AWWA Standard for Deep Wells A100-58.
b. The depth of the casing shall comply with the requirements of Table 5 of this bulletin, and the top of the casing shall terminate 12 inches above the ground surface or pumphouse floor, and two feet above possible flood level.
c. The well easing diameter for a well in rock shall be not less than six inches (four inches in sandstone or sand and gravel).
d. Each section of casing shall be joined with standard drivepipe couplings and ample full-threaded joints, or by proper welding, so that all joints shall be sound and watertight as installed in the well.
e. Well casing alignment shall not interfere with the proper installation and operation of the pump.
a. Construction of the well shall comply with the requirements of Table 5 and other standards given in this bulletin.
b. Construction shall seal off, insofar as practicable, water-bearing formations that are or may be polluted.
c. The well shall be constructed so that no unsealed opening will be left around the well.
d. The well shall be thoroughly developed by proper means to produce maximum yield, clearing it of all excessive sand, silt and turbidity.
e. Water used for well construction shall be of satisfactory sanitary quality.
f. If the well is finished in a sand or gravel formation, the driller shall furnish and install a metal screen of proper diameter, design and standard manufacture, which shall permit maximum transmission of water without clogging.
Grouting as required by Table 5 shall be performed and placed as described in this bulletin.
7. Yield Test
Before being put into use, the well shall be tested for yield and drawdown for at least 4 hours duration. The test pump shall have a capacity at least equal to the pumping rate at which it its expected the well will be pumped during its usage. The test pump shall be installed to operate continuously until the water level has stabilized and, at this point, the yield and drawdown determined. Periodic water level observations shall be made during the drawdown and subsequent recovery periods. A minimum sustained well yield of 5 gallons per minute shall be obtained.
The well shall be pumped until clear and then disinfected as explained in this bulletin.
Temporary capping of the well until the pumping equipment its installed shall be such that no pollutant can enter the well.
The driller shall furnish the owner with accurate and complete information and well log on the form given in this bulletin upon completion of construction.
11. Water Samples
After the well has been pumped clear, and after all chlorine disinfectant has been removed, one or more water samples shall be collected and examined in a New York State Department of Health approved laboratory for bacteriological examination. ( Chemical examination may also be required. )
12. Well Seal and Pitless Adapter
a. A well cap, seal and/or pitless adapter shall be provided to cap a well and to establish and maintain a tight junction between the well casing and the piping or equipment installed therein to prevent pollution from entering the well at the upper terminal.
b. The well cap, seal and/or pitless adapter shall comply with the National Sanitation Foundation Basic Criteria for Pitless Well Adapters or equal as approved by the Health Department.
13. Pump and pumping equipment
Pump and pumping equipment shall be installed so as to comply with the objectives shown in this bulletin.
14. Abandoned Well
An abandoned well shall be filled and sealed in such a manner as to avoid accidents and to prevent it from acting as a channel for pollution of water-bearing formations, and as noted in this bulletin.
Gallons per foot
The annular open space on the outside of the well casing is one of the principal avenues through which undesirable water and contamination. may gain access to a well. The most satisfactory way of eliminating this hazard is to fill the annular space with neat cement grout. To accomplish this satisfactorily, careful attention should be given to see that:
1. The grout mixture is properly prepared.
2. The grout material is placed in one continuous mass.
3. The grout material is placed upward from the bottom of the space to be grouted.
Neat cement grout should be a mixture of cement and water in the proportion of 1 bag of cement (94 pounds) and 5 to 5-1/2 gallons of clean water. Wherever possible, the water content should be kept near the lower limit given. Hydrated lime to the extent of 10 percent of the volume of cement may be added to make the grout mix more fluid and thereby facilitate placement by the pumping equipment. Mixing of cement or cement and hydrated lime with the water must be thorough.
The grout mixture must be placed in one continuous mass; hence, before starting the operation, sufficient materials should be on hand and other facilities available to accomplish its placement without interruption.
Restricted passages will result in clogging and failure to complete the grouting operation. The minimum clearance at any point, including couplings, should not be less than 1 1/2 inches. When grouting through the annular space, the grout pipe should not be less, than 1 inch nominal diameter. As the grout moves upward, it picks up much loose material such as results from caving. Accordingly? it is desirable to waste a suitable quantity of the grout which first emerges from the drill hole.
In grouting a well so that the material will move upward, there are two general procedures that may be followed. The grout pipe may be installed within the well casing or in the annular space between the casing and drill if there is sufficient clearance to permit this: In the latter case, the grout pipe is installed in the annular space to within a few inches of the bottom. The grout is pumped through this pipe, discharging into the annular space, and moving upward around the casing, finally overflowing at the land surface. In 3 to 7 days the grout will be set, and the weld can be completed and pumping started.
When the grout pipe is installed within the well casing. the casing should be supported a few inches above the bottom during grouting to permit grout to flow into the annular space. The well casing is fitted at the bottom with an adapter threaded to receive the grout pipe and a check valve to prevent return of grout inside of the casing. After grout appears at the surface, the casing is lowered to the bottom and the grout pipe is unscrewed immediately and raised a few inches. A suitable quantity of water should shell be pumped through it, thereby flushing any remaining grout from it and the casing. The grout pipe is then removed from the well and 3 to 7 days ale allowed for setting of the grout. The well is shell cleared by drilling out the adapter, check valve, plug, and grout remaining within the well.
A modification of this procedure its the use of the well casing itself to convey the grout to the annular space. The casing is suspended in the drill hole and held several feet off the bottom. A spacer is inserted in the casing. The casing is then capped and connection made from it to grout pump. The estimated quantity of grout, including a suitable allowance for filling of crevices and other voids, is then pumped into the casing. The spacer moves before the grout, in turn forcing the water in the well ahead of it. Arriving at the lower casing terminal the spacer is forced to the bottom of the drill hole, leaving sufficient clearance to permit flow of grout into the annular space and upward through it.
After the desired amount of grout has been pumped into the casing the cap is removed and a second spacer is inserted in the casing The cap is then replaced anti a measured volume of water sufficient to fill all but a few feet of the casing is pumped into it. Thus all but a small quantity of the grout is forced from the casing into the annular space. From 3 to 7 days are allowed for setting of the grout. The spacers and grout remaining in the casing anti drill hole are then drilled out and the well completed.
If the annular space is to be grouted for only part of the total depth of the well, the grouting can be carried out as directed above when the well reaches the desired depth, and the well can then be drilled deeper by lowering the tools inside of the first easing. In this type of construction where casings of various sizes telescope within each other, a seal should be placed at the level where the telescoping begins, that is, in the annular space between the two casings. The annular space for grouting between two casings should provide a clearance of at least 1 1/2 inches, and the depth of the seal should be not less than 10 feet.
This information has been taken principally from a pamphlet of the Wisconsin State Board of Health entitled "Method of Cement Grouting for Sanitary Protection of Wells." The subject is discussed in greater detail in that publication. (Note: Publication is out of print.)