401.1
Well casing and liner
material: Well casings and liners shall be made of a material and weight
appropriate to assure adequate performance of the functions for which they are
used. The minimum characteristics of well casing and liners are as follows:
401.1.1
Contaminants from casing and
liners: Casing and liner material shall not be a source of
pollution.
401.1.2
Steel
casing or liners: Steel well casing or liners shall have a minimum wall
thickness of .250 inches.
401.1.3
Plastic casing or liners: Plastic well casing or liners shall be
schedule 40 or heavier and National Sanitation Foundation approved for potable
water use, including but not limited to Polyvinylchloride (PVC), Chlorinated
polyvinyl chloride (CPVC), or Acrylonitrile butadiene styrene (ABS) or a
Commission approved substitute.
401.2
Well casing placement:
Well casing placement shall be as follows:
401.2.1
General: Casings shall
prevent intrusion of contaminants from the ground surface or unconsolidated
soil layers into the well.
401.2.2
Soil particles: Casings shall prevent entrance of soil particles
into the well.
401.2.3
Termination above ground: Well casings shall extend above ground
surface a minimum of eight inches. Additional height or a vented water tight
cap may be required to prevent entrance of surface water in areas prone to
flooding. (see 402.0)
401.3
Covers: Well casings shall
have a cover to prevent the entrance of foreign matter into the well.
401.4
Drive shoe or coupling:
Drive shoe or coupling shall be used for all rotary drilled wells to assist in
sealing the casing into bedrock when steel casing is used. A coupling may be
used in an open hole setting.
401.5
Casing extension into bedrock: It shall be the responsibility of
the Water Well Contractor to install a sufficient length of well casing into
bedrock, and to affect a proper seal in order to prevent surface water and
shallow ground water from transmitting gravel, sand, silt, clay, and coliform
bacteria into the wellbore at the bottom of the casing or anywhere along the
length of the casing. The below requirements shall not preclude the use of
additional protective measures if approved by the Commission.
401.5.1
Twenty (20) foot minimum:
For any drilled bedrock well, in addition to the requirements of 401.5,
a contractor is responsible for the installation of a minimum of 20 feet of
casing. At least 10 feet of casing extending into the bedrock is
recommended.
401.5.2
Plastic
casing seal: When plastic casing is used, the seal shall be created by
using a "jaswell" type seal tip, shale packer or equal, and the casing shall be
placed in an open hole.
401.5.3
Steel casing seal: "Jaswell" type seal tips, shale packers or
their equal may be used on steel casing when the casing is placed in an open
hole.
401.5.4
Void area
seal: The void area outside the casing shall be filled with cement
grout, bentonite or ledge cuttings.
401.5.5
Bit size: All wells
shall be started with a bit at least .5 inches larger than the drive shoe or
coupling being used, except when a casing underreamer is used.
401.5.6
Cable tool wells: For
cable tool wells, a tapered hole with ledge drilling or bentonite grout is an
acceptable substitute for a drive shoe.
401.5.7
Placement of liners: All
liners mustbe installedin such a manner that they will stay permanently in
place, unless intentionally removed at a later date.
401.5.8
"Jaswell" type seals installed
on liners: When "Jaswell" type seal tips are installed on liners, they
shall be water-tight and leak-free.
401.5.9
Additional protective
measures: The above requirements shall not preclude the use of
additional protective measures. When the annulus of a well casing is grouted,
it is recommended that the materials, methods and procedures in the "Manual of
Water Well Construction, Second Edition, published in 1998 by the National
Groundwater Association", chapter 4 be used.
