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.
