General well construction requirements

1. Construction water. Water used in the drilling process shall be obtained from a source which will not result in contamination of the well. Chlorination of the water with an initial dosage of not less than fifty milligrams per liter (one gallon [3.78 liters] of laundry bleach or 0.6 pounds [1.32 kilograms] of calcium hypochlorite per one thousand gallons [3.78 kiloliters] of drilling water) is recommended. Waters from surface sources must be chlorinated with a minimum dosage of one hundred milligrams per liter (two gallons [7.56 liters] of laundry bleach or 1.2 pounds [2.64 kilograms] of calcium hypochlorite per one thousand gallons [3.78 kiloliters] of drilling water). 2. Ferrous well casing. a. General. Casing and liner pipe of wrought iron or steel through ten inches [25.4 centimeters] in diameter shall be prime pipe meeting current American society for testing and materials schedule 40, or equivalent specifications. Larger diameter pipes shall have a minimum wall thickness of three hundred seventy-five thousandths of an inch [0.952 centimeter]. All casing shall have additional thickness and weight if standard thickness is not considered sufficient to assure reasonable life expectancy of the well or be capable of withstanding forces to which they are subjected. b. Drive shoe. Pipe that is to be driven shall be equipped with a drive shoe or other device approved by the department. c. Joints. Casing and liner pipe joints shall be properly welded or threaded. 3. Nonferrous well casing. a. General. Pipe other than wrought iron or steel must be adaptable to the stresses to which they will be subjected during and after installation and to the corrosiveness of the water. b. Thermoplastic well casing. Thermoplastic well casing shall conform with American society for testing and materials specification F480-81 or latest revision as follows: (1) Minimum standard dimension ratio shall be twenty-one for casings less than sixteen inches [40.64 centimeters] in diameter. Minimum standard dimension ratio shall be twenty-six for casings sixteen inches [40.64 centimeters] in diameter or larger. Casings with a lower standard dimension ratio (additional thickness) must be used when the minimum standard dimension ratio is not capable of withstanding the stresses encountered during and after installation. (2) Minimum pipe stiffness shall be two hundred twenty-four pounds/foot [inch . inch] (kiloneutron/[meter . meter]) when tested according to section 5.4.1 of American society for testing and materials specification F480. (3) All casing five inches [12.7 centimeters] and larger shall be tested for impact resistance and meet or exceed IC-1 impact classification according to section 6.5 and table 6 of American society for testing and materials specification F480. c. Other materials. Other well casing materials that may be proposed shall carry the seal of the national sanitation foundation and be approved in writing by the department prior to installation. 4. Packers. Packers shall be of a material that will not impart taste, odors, toxic substances, or bacterial contamination to the water in the well. 5. Screens. Screens must be constructed of corrosion-resistant material and sufficiently strong to withstand stresses encountered during and after installation. Screen slot openings, screen length, and screen diameter should be sized and designed to provide sufficient open area consistent with strength requirements to transmit sand-free water at a capacity at least equal to one and one-half times the capacity of water anticipated. Screen slot size should be based on sieve analysis of formation samples. Screens should be installed so that exposure above pumping level will not occur. A screen must be attached or connected to the casing by a threaded, solvent-welded, or welded joint or by threaded fasteners or a nontoxic packer. Solvent-welded joints should not impart taste, odors, toxic substances, or bacterial contamination to the water in the well. 6. Filter pack. Material used as a filter pack shall be sand or sand and gravel that is free of foreign material, properly sized, washed, and then disinfected prior to or during placement. Provisions for prevention of leakage of grout into the filter pack or screen shall be provided. 7. Well development. Every well shall be developed prior to yield and drawdown testing. Well development includes procedures to apply physical energy to the screen and aquifer formation adjacent to the well. After development, the well should produce sand-free water at a capacity at least equal to one and one-half times the capacity of water anticipated. 8. Yield and drawdown test. Every well should be tested for yield and drawdown. The test method to be followed should be clearly outlined in the specifications. The test pump should have a maximum capacity at least equal to one and one-half times the capacity of water anticipated. The test pump should be able to operate continuously until the rate of decline of the pumping water level has stabilized. Test data to be recorded should include: a. Static water level. b. Pumping rate. c. Drawdown during test. d. Recovery water levels. e. Depth of pump setting. Duration of the test shall be determined with due consideration given to pumping of sand, clarity of water pumped, and the obtaining of a representative sample of water for chemical analysis. 9. Chemical conditioning. When chemical treatment of a public well is proposed, the method of conditioning shall be included in the specifications. The equipment, chemicals, and inhibitors to be used, the method of testing for chemical residuals, and the disposal of waste shall be indicated. 10. Grouting requirements. a. Neat cement grout. The mixture should consist of one sack of cement (ninety-four pounds [42.64 kilograms]) to not more than six gallons [22.71 liters] of clean water. Bentonite additives up to five pounds [2.27 kilograms] per sack of cement to increase fluidity may be used. Pozzuolana additives up to thirty-three pounds [14.97 kilograms] per sack of cement may be used. b. Heat of hydration. Care must be used when grouting thermoplastic well casing with neat cement grout. Heat caused by hydration during curing of the cement may cause weakening of the well casing. High peak temperatures may be minimized by adding sand or bentonite clay to the neat cement grout mixture to increase the curing time. The amount of sand or bentonite clay added to the neat cement grout may not exceed five pounds [2.27 kilograms] per sack of cement. c. High-solids bentonite clay grout. The mixture must consist of not less than three pounds [1.36 kilograms] of bentonite clay per gallon [3.79 liters] of clean water. High-solids bentonite clay grout, bentonite chips, or bentonite tablets must be commercially prepared specifically for the purpose of sealing water wells. The use of bentonite drilling fluids as a grouting material is not permitted. d. Grouting guides. Casing that is to be grouted in the drill hole or annular opening shall be provided with sufficient guides welded to the casing to permit the unobstructed flow and uniform thickness of grout. e. Grout application. Grout material must be positively and accurately placed to fill all voids. All grouting should be performed by adding the mixture, from the bottom of the annular space upward, in one continuous operation, until the annular space is filled. Sufficient annular opening shall be provided to permit a minimum of one and one-half inches [3.81 centimeters] of grout around the casing, including couplings, if used. Bentonite chips or tablets may be added from the top of the annular space to a maximum depth of thirty feet [9.1 meters] provided the grout material is positively and accurately placed to fill all voids and hydrated after placement. 11. Plumbness and alignment. Every well shall be tested for plumbness and alignment upon completion of construction. The casing shall be sufficiently plumb so as not to interfere with the installation and operation of the pump. (See recommended procedures in the appendix to this chapter.) 12. Well construction data. The water well contractor shall provide the North Dakota board of water well contractors with an accurate record of well construction data. Drill cuttings should be obtained at five-foot [1.52-meter] intervals, and at all pronounced changes in formation. Well construction data shall include an accurate record of the drill hole diameters and depths, assembled order of size and length of casings and liners, grouting depths, formations penetrated, water levels, location of blast shots, and pumping tests. Well construction report forms are available from the North Dakota board of water well contractors. 13. Upper terminal of well. The casing or pitless unit for all ground water sources shall project not less than twelve inches [30.48 centimeters] above the final ground elevation, the well cover slab, or pumphouse floor. Sites subject to flooding shall have the top of the protective casing, pitless unit, the cover of every dug well, and the floor of the pumphouse at least two feet [60.96 centimeters] above the highest-known flood elevation and be surrounded by earthfill. 14. Capping. The well must be protected during construction. A properly fitted cap designed for the type of well casing installed shall be used to protect the well from surface contamination until pumping equipment is installed. 15. Bacteriological and chemical quality of water. Every new, modified, or reconditioned ground water source shall be thoroughly cleaned and disinfected after the completion of construction and again after the permanent pump has been installed. The certified water well contractor or pump and pitless unit installer in charge during well construction and pump installation shall advise the well owner that one or more water samples from the source should be submitted to an approved laboratory for bacteriological analysis and that the well should not be placed into service until satisfactory bacteriological results are obtained. Wells intended for use by a public water system shall be sampled for bacteriological analysis and the following chemicals and not placed into service until the results are deemed by the department to comply with the primary drinking water standards established under the Safe Drinking Water Act: antimony, arsenic, barium, beryllium, cadmium, chromium, copper, cyanide, fluoride, lead, mercury, nickel, combined nitrate/nitrite, selenium, thallium, manganese, and sulfate. When it is established that the ground water is subject to continuous or intermittent contamination, or for public water systems that the ground water is under the direct influence of surface water, provisions for continuous disinfection will be required. 16. Chemical quality of water. Every new, modified, or reconditioned ground water source should be examined for its chemical characteristics by tests of a representative sample in a department or other approved laboratory. The samples should be collected and tested as soon as practical. 17. Water level measurement. Provisions should be made for periodic measurement of the static and pumping water levels in the completed well. The installation shall be made in such manner as to prevent the entrances of foreign material. 18. Water supply wells, geothermal ground water and return wells, and special purpose water wells. All wells designed as water supply wells, geothermal ground water or return wells, or special purpose water wells shall be constructed in accordance with this chapter. Each well shall be protected at its upper terminal to preclude the entrance of foreign materials. 19. Abandoned wells. Any abandoned water wells, including test wells, uncompleted wells, and completed wells shall be sealed by restoring, as far as possible, the controlling geological conditions which existed before the wells were drilled. Sealing of wells results in: a. Elimination of physical hazards. b. Prevention of contamination of ground water. c. Conserving yield and hydrostatic head of aquifers. d. Prevention of intermingling of desirable and undesirable waters. Wherever feasible, the wells should be filled with concrete grout or other approved materials. (Note: recommended grouting procedures are in the appendix to this chapter.) At no time shall any sewage or other contaminated or toxic materials be discharged into an abandoned well. 20. Organic polymers. The use of biodegradable organic polymers as a drilling fluid additive has resulted in persistent microbiological contamination of ground water supplies. Organic polymers shall be used only when approved in writing by the department for a specific well construction project.