1. Hand dug wells and
bored wells no deeper than eighty feet (80'). To plug this type of well,
the following steps must be followed (see Figure
9):
A. Remove all pumps,
pipe, debris and surface coverings or concrete cap;
B. Push in top three
feet (3') of well lining. Lining may be composed of rock, brick or tile.
If lining is composed of any other material consult the division for further
instructions;
C. Fill well to within
three feet (3') from the surface with clean fill such as gravel, sand,
varied sized agricultural lime or other approved material;
D. Disinfect fill
material. If there is water in the well, chlorine must be added to bring
its concentration to at least one hundred (100) parts per million (ppm)
(see Table
1 in 10
CSR 23-3.050). As the fill material is poured into the well, it is
disinfected as it comes in contact with the chlorinated water. If there
is no water in the well to be plugged, disinfect the fill material before
it is placed into the well;
E. Fill the remaining
hole with clay or clay-rich soil. Soil should be mounded slightly at the
top to help offset settling; and
F. Submit the registration
report form and fee to the division.
2. Wells completed in
unconsolidated deposits. This type of well includes alluvial wells, glacial
drift wells and nonbedrock wells. To plug this type of well, the following
steps must be followed:
A. Remove all pumps,
pipe and debris from well;
B. Dig around casing
and remove top three feet (3') of casing. The remaining hole must be at
least two feet (2') in diameter larger than the existing casing (see Figure
10);
C. Fill well from
total depth to fifty feet (50') from surface with clean fill such as gravel,
sand, varied sized agricultural lime or other approved material;
D. Disinfect fill
material. If there is water in the well, you must add chlorine to the
water bringing it to a concentration of at least one hundred (100 ppm)
(see Table
1 in 10
CSR 23-3.050). As the fill material is poured into the well, it is
disinfected as it comes in contact with the chlorinated water. If there
is no water in the well to be plugged, disinfect the fill material before
it is placed into the well;
E. Place a grout plug
that fills the upper fifty feet (50') of casing and extends into the larger
excavated area, at least one foot (1'). In agricultural or yard settings
the remaining hole above the grout plug must be filled with soil. In other
settings, the remaining hole above the grout plug may be filled with clean
fill if the well site is to be paved; and
F. Submit registration
report form and fee to the division.
3. Wells completed in
bedrock. This type of well includes any domestic well that produces water
from bedrock aquifers (see Figure
11). To plug this type of well, the following steps must
be followed:
A. Remove all pumps,
pipe and debris from well. Any liner must be removed or perforated if
possible;
B. Dig around casing
and remove top three feet (3') of casing. The remaining hole must be at
least two feet (2') in diameter larger than the existing casing;
C. Fill well from
total depth to fifty feet (50') below bottom of casing with clean fill
such as gravel, sand, varied sized agricultural lime or other approved
fill material;
D. Disinfect fill
material. If there is water in the well, you must add chlorine to the
water bringing it to a concentration of at least one hundred (100) ppm
(see Table
1 in 10
CSR 23-3.050). As the fill material is poured into the well, it is
disinfected as it comes in contact with the chlorinated water. If there
is no water in the well to be plugged, disinfect any fill material used
before it is placed into the well;
E. Place cement or
bentonite from a point fifty feet (50') below the bottom of the casing
to two fee (2') from the suface making sure the grout extends into the
excavated area at least one foot (1'). If the water level is above a point
fifty feet (50') below the bottom of the casing, then bentonite chips
must be used or the cement or bentonite slurry must be emplaced through
a tremie pipe lowered through the water level to the top of the fill.
Under no circumstances may cement or bentonite slurry be poured through
large columns of water without the use of a tremie pipe (see paragraph
(2)(C)6. for alternative cement plugging technique);
F. May plug the well,
if the well has one hundred fifty feet (150') or more of casing, by filling
the well with clean aggregate to a point fifty feet (50') below the bottom
of the casing, placing a grout plug from this point extending up into
the casing thirty feet (30'). From this point to within fifty feet (50')
of the surface, clean aggregate fill may be used. From fifty feet (50')
to two feet (2') must be filled with grout making sure the grout extends
into the excavated area at least one foot (1');
G. Cut casing off
at top of bedrock, if bedrock is encountered when digging around the casing,
and fill remaining hole with cement slurry. In agricultural or yard settings,
the plug must terminate at least two feet (2') below the finished surface
grade and the remaining hole filled with soil. In other settings, the
remaining hole may be filled with clean fill if the well site is to be
paved; and
H. Submit registration
report form and fee to division.
4. For those wells which
casing depth, water level and total depth are not known and cannot be determined,
plugging instructions will be determined on a case-by-case basis and may
be more stringent.
5. As clean fill is
being placed into a well, periodic measurements should be taken to ensure
that the fill does not reach a point closer than fifty feet (50') below
the bottom of the existing casing. If fill is placed above this point, plugging
schedules will be determined by the division and may result in removal of
fill material.
6. When plugging a well
that contains water that is above a point of fifty feet (50') below the
bottom of the casing or liner, whichever is deeper, cement slurry may be
poured into the well if a tremie pipe is placed in the well to near the
bottom and acts as a conduit for the water to escape through as the cement
slurry is poured into the well casing from the surface. The cement slurry
must be poured in one (1) continuous operation. Mixing small batches and
pouring is not permitted.
7. The flow in a flowing
well shall be confined, if possible, and the well plugged in accordance
with well plugging requirements supplied by the division which will be determined
on a case-by-case basis. Proper judgment shall be exercised in the feasibility
of plugging flowing wells. In some cases the confining formation may have
been so badly disturbed that plugging may only cause the flow to discharge
in a less appropriate location. In other situations, the flow may have eroded
so much material that the landscape has taken on the appearance of a natural
spring. The plugging in this case may be impractical, if not impossible.
