Current through Register Vol. 48, No. 38, September 20, 2024
a) Except as provided otherwise in subsection
(b), the groundwater monitoring system must consist of a sufficient number of
wells, installed at appropriate locations and depths to yield groundwater
samples, that:
1) Represent the quality of
background water that has not been affected by contamination from the facility
or unit; and
2) Represent the
quality of groundwater at the compliance point or points.
b) If a potable water well or other water
well can be used as a monitoring well under this subsection, no additional
monitoring wells are required under this Section. A potable water well or other
water well may be used as a monitoring well if:
1) For a potable water well other than a
community water supply well, a construction report has been filed with the
Illinois Department of Public Health for such well, or such well has been
located and constructed (or reconstructed) to meet the Illinois Water Well
Construction Code [415 ILCS 30 ] and 35 Ill. Adm.
Code 920;
2) For a potable water
supply well that was constructed before August 20, 1965, the enactment of the
Illinois Water Well Construction Code [415 ILCS 30
], and meets all of the following criteria:
A) Construction must be done in a manner that
will enable the collection of groundwater samples that represent in situ
groundwater conditions;
B) Casings
and screens must be made from durable material resistant to expected chemical
or physical degradation that does not interfere with the quality of groundwater
samples being collected; and
C) The
annular space opposite the screened section of the well (i.e., the space
between the bore hole and well screen) must be filled with gravel or sand if
necessary to collect groundwater samples. The annular space above and below the
well screen must be sealed to prevent migration of water from adjacent
formations and the surface to the sampled depth.
3) For a water well other than a potable
water well (e.g., a livestock watering well or an irrigation well), the owner
or operator of the unit seeking to use the well as a monitoring well certifies
to the Agency that a construction report has been filed with the Illinois
Department of Public Health or the Illinois Department of Mines and Minerals
for such well, or that such well has been located and constructed (or
reconstructed) to meet the Illinois Water Well Construction Code [415 ILCS
30 ] and 35 Ill. Adm. Code 920; and
4) The unit contains solely non-special waste
if the unit is a surface impoundment.
c) When a facility contains more than one
unit, separate groundwater monitoring systems are not required for each unit if
provisions for sampling the groundwater will enable detection and measurement
of contaminants that have entered the groundwater from all units.
d) All monitoring wells must meet the
following requirements:
1) Construction must
be done in a manner that will enable the collection of groundwater
samples;
2) Casings and screens
must be made from durable material that is resistant to expected chemical or
physical degradation and that does not interfere with the quality of
groundwater samples being collected; and
3) The annular space opposite the screened
section of the well (i.e., the space between the bore hole and well screen)
must be filled with gravel or sand if necessary to collect groundwater samples.
The annular space above and below the well screen must be sealed to prevent
migration of water from overlying adjacent formations and the surface to the
sampled depth.
