Current through Register Vol. 48, No. 38, September 20, 2024
a)
Drilling fluids and additives must not impart any toxic substance to the water
or promote bacterial contamination.
b) Minimum protected depths of drilled wells
must provide watertight construction to exclude contamination and seal off
formations that are, or may be, contaminated or yield undesirable
water.
c) Surface or temporary
steel casing used for construction must be capable of withstanding the
structural load imposed during its installation and removal. Surface or
temporary casing must be removed during or prior to grouting or it must be
grouted in place when set according to subsection (i).
d) The well casing material must be steel.
Permanent steel casing pipe must:
1) be new
single steel casing pipe meeting AWWA A100, incorporated by reference in 35
Ill. Adm. Code
601.115,
for water well construction;
2)
have a minimum weight and thickness indicated in Table A;
3) be equipped with a drive shoe when driven;
and
4) have full circumferential
welds or threaded coupling joints.
e) All wells during construction must be
protected against the entrance of water, contaminants and tampering. Methods
for capping a well include a welded metal plate and a threaded cap.
f) Packers must be of material that will not
impart taste, odor, toxic substances or bacterial contamination to the well
water. Lead packers must not be used.
g) Screens must:
1) be constructed of materials resistant to
damage by chemical action of groundwater or cleaning operations;
2) have size of openings based on sieve
analysis of formation and/or gravel pack materials;
3) have sufficient length and diameter to
provide adequate specific capacity and low aperture entrance
velocity;
4) be installed so that
pumping water level remains above the screen under all operating conditions;
and
5) be provided with a bottom
plate or washdown bottom fitting of the same material as the screen.
h) Grouting Requirements. The
annulus of all permanent well casings must be grouted from the original ground
surface or pitless unit to a minimum depth of 10 feet utilizing a minimum
thickness of 11/2 inches of grout.
1)
Neat Cement Grout. Cement conforming to AWWA A100 and water, with not more than
six gallons of water per 94 pounds of cement, must be used for 11/2 inch
openings.
2) Concrete Grout. Equal
parts of cement conforming to AWWA A100 and sand, with not more than six
gallons of water per 94 pounds of cement, may be used for annular openings
larger than 11/2 inches. For annular openings greater than four inches,
gravel added to the concrete must not exceed 1/2 inch.
3) Application
A) A minimum thickness of 11/2 inches of
grout around permanent casings, including couplings, must be
provided.
B) Prior to grouting
through creviced or fractured formations, bentonite or similar materials may be
added to the annular opening, in the manner indicated for grouting.
C) When the annular opening is less than four
inches, grout must be installed under pressure by means of a grout pump from
the bottom of the annular opening upward in one continuous operation until the
annular opening is filled.
D) When
the annular opening is four inches or greater and extends less than 100 feet,
and concrete grout is used, it may be placed by gravity through a grout pipe
installed to the bottom of the annular opening in one continuous operation
until the annular opening is filled.
E) Grout must be allowed to overflow from the
annular opening until the proper density or percent solids has been
achieved.
F) Standby grouting
equipment for grouting annular openings, including a backup grout pump and
tremie pipe, must be on site during the grouting of all wells.
G) The conductor pipe must be completely
withdrawn from the well prior to flushing excess grout from the conductor pipe
when grouting down the annular space or must be disconnected from the grout
shoe or street elbow prior to flushing excess grout when grouting within the
casing.
H) After cement grouting is
applied, work on the well must be discontinued until the cement or concrete
grout has properly set.
I) Grout
placement must be sufficient to achieve proper density or percent solids
throughout the annular space.
4) Guides. The casing must be provided with
sufficient guides welded to the casing to center the casing in the drill hole,
prevent displacement of the casing and still permit unobstructed flow and
uniform thickness of grout.
i) Upper Terminal Well Construction
1) Permanent casing for all groundwater
sources must project at least 12 inches above the pumphouse, well platform
floor or concrete apron surface and at least 18 inches above final ground
surface.
2) Where a well house is
constructed, the floor surface must be at least six inches above the final
ground elevation.
3) Protection
from physical damage must be provided.
4) The upper terminal must be constructed to
prevent contamination from entering the well.
5) Where well appurtenances protrude through
the upper terminal, the connections to the upper terminus must be mechanical or
welded connections that are watertight.
j) Upper Terminal Well Construction in the
Flood Plain of a 100-year Flood or Flood of Record
1) Sites subject to flooding must be provided
with an earth mound to raise the well house floor to an elevation at least two
feet above the highest known flood elevation, or other suitable protection as
determined by the Agency. A 15-foot horizontal distance must be
maintained.
2) The top of the well
casing at sites subject to flooding must terminate at least three feet above
the 100-year flood level or the highest known flood elevation, whichever is
higher, or as otherwise approved by the Agency under Section
604.145(b).
3) Wells must have a
six-inch concrete envelope completely surrounding the regular casing and
extending at least 10 feet below original ground surface.
k) Development
1) Every well must be developed to remove the
native silts and clays, drilling mud or finer fraction of the gravel
pack.
2) Development must continue
until the maximum specific capacity is obtained from the completed
well.
3) Where chemical
conditioning is required, specifications submitted to the Agency under 35 Ill.
Adm. Code 602 must include provisions for the method, equipment, chemicals,
testing for residual chemicals, and disposal of waste.
4) Where blasting procedures are used,
specifications submitted to the Agency under 35 Ill. Adm. Code 602 must include
the provisions for blasting and cleaning. The grouting and casing must not be
damaged by the blasting.
l) When an operating permit is not required
under 35 Ill. Adm. Code 602, disinfection of modified or reconditioned wells
must be provided, and a record of microbiological sample results must be
maintained for five years.
m) Test
wells and groundwater sources that are not in use must be sealed in accordance
with 77 Ill. Adm. Code
920.120. The
sealing form specified in 77 Ill. Adm. Code
920.120(e)(2)
must be submitted to the Agency not more than 30 days after the well is
sealed.
