**NATURAL RESOURCES CONSERVATION SERVICE**

**Idaho**

**CONSTRUCTION SPECIFICATIONS**

**FOR**

**WATER WELL**

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(Owner/Operator)

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(Project/Title)

GENERAL

Installation shall be in accordance with a design and plan approved by
the responsible technician. Details of construction shown in the design
and plan or described in the State of Idaho "Well Construction
Standards, Rules and Regulations" but not included here shall be
considered as a part of this specification. Construction activities
shall be in accordance with applicable OSHA regulations.

CASING

[Steel Pipe]{.underline}. Steel pipe used for well casing shall meet or
exceed the requirements specified in ASTM A 589.

[Plastic Pipe]{.underline}. Plastic pipe used for well casing shall
conform to ASTM F 480. Plastic casings for transporting potable water
supplies shall be NSF approved.

[Joint Strength]{.underline}. Well casing joints shall have adequate
strength to carry the load due to the casing length and still be
watertight, or shall be mechanically supported during installation to
maintain joint integrity. Such mechanically supported casings shall
terminate on firm material that can adequately support the casing
weight.

SCREEN

A well screen shall be installed in any earth material likely to produce
silt or sand. Well screens may be constructed of commercially
manufactured screen sections, well points, or field-perforated sections.

Perforation by any method is allowable provided proper slot size and
entrance velocity limits can be met. The length and open area of the
screen shall be sized to limit entrance velocity of water into the well
to less than or equal to 0.1 foot per second.

Depth of the aquifer below ground surface and the thickness of aquifer
to be penetrated by the well shall govern the position of the screen in
the well.

Maximum drawdown shall not be permitted below the top of the highest
screen or pump intake.

Telescoped screen assemblies shall be provided with one or more
sand-tight seals between the top of the telescoped screen assembly and
casing.

Installation of a filter pack around the well screen shall be considered
under the following conditions: presence of a poorly graded, fine sand
aquifer; presence of a highly variable aquifer, such as alternating sand
and clay layers; presence of a poorly cemented sandstone or similar
aquifer; a requirement for maximum yield from a low-yielding aquifer;
and holes drilled by reverse circulation.

For heaving or caving sands, silty or fine-grained aquifers, and for
horizontal or angled wells, a commercial prepacked well screen may be
substituted for a conventionally installed (by tremie) filter pack.

INSTALLATION

[Borehole]{.underline}. Drilled, jetted, bored, and driven wells shall
be sufficiently round, straight, and of adequate diameter, to permit
satisfactory installation of inlet, well casing, filter pack, and
annular seal, and passage of tremie pipe (including couplings), if used.

[Use of Casing]{.underline}. Casing shall be installed to seal out
undesirable surface or shallow ground water and to support the side of
the hole through unstable earth materials. The intake portion of a well
through stable geologic formations may not require casing. Steel casing
shall be used in driven wells.

All wells shall be cased to a sufficient height (minimum of 12 inches)
above the ground surface to prevent entry of surface and near-surface
water.

Casing for artesian aquifers shall be sealed into overlying, impermeable
formations in such a manner as to retain confining pressure.

If a zone is penetrated that is determined or suspected to contain water
of quality unsuitable for the intended use, the zone shall be sealed to
prevent infiltration of the poor-quality water into the well and the
developed portion of the aquifer.

Casing shall extend from above the ground surface down through unstable
earth materials to an elevation of at least 2 feet into stable material
or to the top of the screen.

[Casing Diameter]{.underline}. Casing diameter shall be sized to permit
satisfactory installation and efficient operation of the pump, and large
enough to assure that uphole velocity is 5 feet per second or less, to
protect against excessive head loss.

[Well Development]{.underline}. Wells to be completed without a filter
pack in unconsolidated granular aquifers shall be developed following
guidance provided in ASTM D 5521, Standard Guide for Development of
Ground-Water Monitoring Wells in Granular Aquifers. The method shall be
selected based on geologic character of the aquifer, type of drilling
rig, and type of screen.

[Aquifer Development]{.underline}. For massive, unfractured rock
formations unresponsive to well development procedures, the use of
aquifer stimulation techniques may be considered to improve well
efficiency and specific capacity. Techniques may include dry ice,
acidizing, explosives, or hydrofracturing, depending on the composition
and structure of the formation.

[Grouting and Sealing]{.underline}. The annulus surrounding the
permanent well casing at the upper terminus of the well shall be filled
with expansive hydraulic cement (ASTM C 845), shrinkage-compensating
concrete, bentonite-based grout, clay, or other material with similar
sealing properties. The length of the grout seal shall be no less than
10 feet and not less than the minimum specified in state or locally
applicable construction codes.

If the water is intended for human consumption, the casing shall be
surrounded at the ground surface by a 4-inch thick concrete slab
extending at least 2 feet in all directions.

A positive seal (grouted in place) or packer shall be provided between
the casing and the less pervious material overlying the aquifer of
artesian wells, and in all aquifers where co-mingling of waters is
undesirable.

[Access Port]{.underline}. An access port with a minimum diameter of 0.5
inch shall be installed to allow for unobstructed measurement of depth
of the water surface, or for a pressure gage for measuring shut-in
pressure of a flowing well. Access ports and pressure gages or other
openings in the cover shall be sealed or capped to prevent entrance of
surface water or foreign material into the well. Removable caps are
acceptable as access ports.

[Disinfection]{.underline}. Wells shall be disinfected immediately
following their construction or repair to neutralize any contamination
from equipment, material, or surface drainage introduced during
construction. The disinfection process shall comply with all local or
state requirements.

[Water Quality Testing]{.underline}. Sampling and testing shall comply
with all applicable federal, state, and local requirements associated
with the intended use(s) of the water.

ADDITIONAL SPECIFICATIONS