Current through Register Vol. 48, No. 38, September 20, 2024
a)
Applicable Groundwater Quality Standards
1)
Groundwater quality must be maintained at each constituent's background
concentration, at or beyond the zone of attenuation. The applicable groundwater
quality standard established for any constituent must be:
A) The background concentration; or
B) The Board established standard adjusted by
the Board in accordance with the justification procedure of subsection
(b).
2) Any statistically
significant increase above an applicable groundwater quality standard
established under subsection (a)(1) that is attributable to the facility and
that occurs at or beyond the zone of attenuation within 100 years after closure
of the last unit accepting waste within such a facility must constitute a
violation.
3) For the purposes of
this Part:
A) "Background concentration"
means that concentration of a constituent that is established as the background
in accordance with subsection (d); and
B) "Board established standard" is the
concentration of a constituent adopted by the Board as a groundwater quality
standard adopted by the Board under Section 14.4 of the Act or Section 8 of the
Illinois Groundwater Protection Act [415 ILCS 55].
b) Justification for Adjusted
Groundwater Quality Standards
1) An operator
may petition the Board for an adjusted groundwater quality standard in
accordance with the procedures specified in Section 28.1 of the Act and 35 Ill.
Adm. Code 104. Subpart D.
2) For
groundwater that contains naturally occurring constituents that meet the
applicable requirements of 35 Ill. Adm. Code
620.410,
620.420,
620.430,
or
620.440
the Board will specify adjusted groundwater quality standards no greater than
those of 35 Ill. Adm. Code 620.410, 620.420, 620.430 or 620.440, respectively,
upon a demonstration by the operator that:
A)
The change in standards will not interfere with, or become injurious to, any
present or potential beneficial uses for the water;
B) The change in standards is necessary for
economic or social development, by providing information including, but not
limited to, the impacts of the standards on the regional economy, social
disbenefits such as loss of jobs or closing of landfills, and economic analysis
contrasting the health and environmental benefits with costs likely to be
incurred in meeting the standards; and
C) All technically feasible and economically
reasonable methods are being used to prevent the degradation of the groundwater
quality.
3)
Notwithstanding subsection (b)(2), in no case must the Board specify adjusted
groundwater quality standards for a MSWLF unit greater than the following
levels:
Chemical
|
Concentration
(mg/l)
|
Arsenic (CAS No. 7440-38-2)
|
0.05
|
Barium (CAS No. 7440-39-3)
|
1.0
|
Benzene (CAS No. 71-43-2)
|
0.005
|
Cadmium (CAS No. 7440-43-9)
|
0.01
|
Carbon tetrachloride (CAS No. 56-23-5)
|
0.005
|
Chromium (hexavalent) (CAS No. 18540-29-9)
|
0.05
|
1,4-Dichlorobenzene (CAS No. 106-46-7)
|
0.075
|
1,2-Dichloroethane (CAS No. 107-06-2)
|
0.005
|
1,1-Dichloroethylene (CAS No. 75-35-4)
|
0.007
|
2,4-Dichlorophenoxy acetic acid (CAS No.
94-75-7)
|
0.1
|
Endrin (CAS No. 72-20-8)
|
0.0002
|
Fluoride (CAS No. 16984-48-8)
|
4
|
Lindane (CAS No. 58-89-9)
|
0.004
|
Lead (CAS No. 7439-92-1)
|
0.05
|
Mercury (CAS No. 7439-97-6)
|
0.002
|
Methoxychlor (CAS No. 72-43-5)
|
0.1
|
Nitrate (CAS No. 14797-55-8)
|
10
|
Selenium (CAS No. 7782-49-2)
|
0.01
|
Silver (CAS No. 7440-22-4)
|
0.05
|
Toxaphene (CAS No. 8001-35-2)
|
0.005
|
l,l,l-Trichloroethane (CAS No. 71-55-6)
|
0.2
|
Trichloroethylene (CAS No. 79-01-6)
|
0.005
|
2,4,5-Trichlorophenoxyacetic acid (CAS No.
93-76-5)
|
0.01
|
Vinyl chloride (CAS No. 75-01-4)
|
0.002
|
BOARD NOTE: Subsection (b)(3) is derived from
40 CFR 258.40
Table 1.
4) For groundwater
that contains naturally occurring constituents that do not meet the standards
of 35 Ill. Adm. Code 620.410, 620.420, 620.430, or 620.440, the Board will
specify adjusted groundwater quality standards, upon a demonstration by the
operator that:
A) The groundwater does not
presently serve as a source of drinking water;
B) The change in standards will not interfere
with, or become injurious to, any present or potential beneficial uses for
those waters;
C) The change in
standards is necessary for economic or social development, by providing
information including, but not limited to, the impacts of the standards on the
regional economy, social disbenefits such as loss of jobs or closing of
landfills, and economic analysis contrasting the health and environmental
benefits with costs likely to be incurred in meeting the standards;
and
D) The groundwater cannot
presently, and will not in the future, serve as a source of drinking water
because:
i) It is impossible to remove water
in usable quantities;
ii) The
groundwater is situated at a depth or location such that recovery of water for
drinking purposes is not technologically feasible or economically
reasonable;
iii) The groundwater is
so contaminated that it would be economically or technologically impractical to
render that water fit for human consumption;
iv) The total dissolved solids content of the
groundwater is more than 3,000 mg/l and that water will not be used to serve a
public water supply system; or
v)
The total dissolved solids content of the groundwater exceeds 10,000
mg/l.
c) Determination of the Zone of Attenuation
1) The zone of attenuation, within which
concentrations of constituents in leachate discharged from the unit may exceed
the applicable groundwater quality standard of this Section, is a volume
bounded by a vertical plane at the property boundary or 100 feet from the edge
of the unit, whichever is less, extending from the ground surface to the bottom
of the uppermost aquifer and excluding the volume occupied by the
waste.
2) Zones of attenuation must
not extend to the annual high-water mark of navigable surface waters.
3) Overlapping zones of attenuation from
units within a single facility may be combined into a single zone for the
purposes of establishing a monitoring network.
d) Establishment of Background Concentrations
1) The initial monitoring to determine
background concentrations must commence during the hydrogeological assessment
required by Section
811.315.
The background concentrations for those parameters identified in Sections
811.315(e)(1)(G)
and
811.319(a)(2) and
(a)(3) must be established based on
consecutive quarterly sampling of wells for a minimum of one year, monitored in
accordance with the requirements of subsections (d)(2), (d)(3) and (d)(4).
Non-consecutive data may be considered by the Agency, if only one data point
from a quarterly event is missing, and it can be demonstrated that the
remaining data set is representative of consecutive data in terms of any
seasonal or temporal variation. Statistical tests and procedures must be
employed, in accordance with subsection (e), depending on the number, type and
frequency of samples collected from the wells, to establish the background
concentrations.
2) Adjustments to
the background concentrations must be made if changes in the concentrations of
constituents observed in background wells over time are determined, in
accordance with subsection (e), to be statistically significant, and due to
natural temporal or spatial variability or due to an off-site source not
associated with the landfill or the landfill activities. Such adjustments may
be conducted no more frequently than once every two years during the operation
of a facility and modified subject to approval by the Agency. Non-consecutive
data may be used for an adjustment upon Agency approval. Adjustments to the
background concentration must not be initiated prior to November 27, 2009
unless required by the Agency.
3)
Background concentrations determined in accordance with this subsection must be
used for the purposes of establishing groundwater quality standards, in
accordance with subsection (a). The operator must prepare a list of the
background concentrations established in accordance with this subsection. The
operator must maintain such a list at the facility, must submit a copy of the
list to the Agency for establishing standards in accordance with subsection
(a), and must provide updates to the list within ten days of any change to the
list.
4) A network of monitoring
wells must be established upgradient from the unit, with respect to groundwater
flow, in accordance with the following standards, in order to determine the
background concentrations of constituents in the groundwater:
A) The wells must be located at such a
distance that discharges of contaminants from the unit will not be
detectable;
B) The wells must be
sampled at the same frequency as other monitoring points to provide continuous
background concentration data, throughout the monitoring period; and
C) The wells must be located at several
depths to provide data on the spatial variability.
5) A determination of background
concentrations may include the sampling of wells that are not hydraulically
upgradient of the waste unit if the following conditions are met:
A) Hydrogeologic conditions do not allow the
owner or operator to determine what wells are hydraulically upgradient of the
waste; and
B) Sampling at other
wells will provide an indication of background concentrations that is
representative of that which would have been provided by upgradient
wells.
6) If background
concentrations cannot be determined on site, then alternative background
concentrations may be determined from actual monitoring data from the aquifer
of concern, which includes, but is not limited to, data from another landfill
site that overlies the same aquifer.
e) Statistical Analysis of Groundwater
Monitoring Data
1) Statistical tests must be
used to analyze groundwater monitoring data. One or more of the normal theory
statistical tests must be chosen first for analyzing the data set or
transformations of the data set. If these normal theory tests are demonstrated
to be inappropriate, tests listed in subsection (e)(4) must be used. The level
of significance (Type I error level) must be no less than 0.01, for individual
well comparisons, and no less than 0.05, for multiple well comparisons. The
statistical analysis must include, but not be limited to, the accounting of
data below the detection limit of the analytical method used, the establishment
of background concentrations and the determination of whether statistically
significant changes have occurred in:
A) The
concentration of any chemical constituent with respect to the background
concentration or maximum allowable predicted concentration; and
B) The established background concentration
of any chemical constituents over time.
2) The statistical test or tests used must be
based upon the sampling and collection protocol of Sections
811.318
and 811.319.
3) Monitored data that
are below the level of detection must be reported as not detected (ND). The
level of detection for each constituent must be the practical quantitation
limit (PQL) and must be the lowest concentration that is protective of human
health and the environment, and can be achieved within specified limits of
precision and accuracy during routine laboratory operating conditions. In no
case, must the PQL be established above the level that the Board has
established for a groundwater quality standard under the Illinois Groundwater
Protection Act. The following procedures must be used to analyze such data,
unless an alternative procedure in accordance with subsection (e)(4), is shown
to be applicable:
A) If the percentage of
non-detects in the data base used is less than 15 percent, the operator must
replace NDs with the PQL divided by two, then proceed with the use of one or
more of the normal theory statistical tests;
B) If the percentage of non-detects in the
data base used is between 15 and 50 percent, and the data are normally
distributed, the operator must use Cohen's or Aitchison's adjustment to the
sample mean and standard deviation, followed by an applicable statistical
procedure;
C) If the percentage of
non-detects in the database used is above 50 percent, then the owner or
operator must use an alternative procedure in accordance with subsection
(e)(4).
4) Nonparametric
statistical tests or any other statistical test if it is demonstrated to meet
the requirements of 35 Ill. Adm. Code
724.197(i).
BOARD NOTE: Subsection (b)(3) is derived from
40 CFR 258.40
Table 1 (2017).