a)
Purpose
The operator shall conduct a hydrogeologic investigation to
develop hydrogeologic information for the following uses:
1) Provide information to perform a
groundwater impact assessment; and
2) Provide information to establish a
groundwater monitoring system.
b) General Requirements
1) The investigation shall be conducted in a
minimum of three phases prior to submission of any application to the Agency
for a permit to develop and operate a landfill facility.
2) The study area shall consist of the entire
area occupied by the facility and any adjacent related areas, if necessary for
the purposes of the hydrogeological investigation set forth in subsection
(a).
3) All borings shall be
sampled continuously at all recognizable points of geologic variation, except
that where continuous sampling is impossible or where non-continuous sampling
can provide equivalent information, samples shall be obtained at intervals no
greater than 1.52 meters (five feet) in homogeneous strata.
c) Minimum Requirements for a
Phase I Investigation
1) The operator shall
conduct a Phase I Investigation to develop the following information:
A) Climatic aspects of the study
area;
B) The regional and study
area geologic setting, including a description of the geomorphology and
stratigraphy of the area;
C) The
regional groundwater regime including water table depths and aquifer
characteristics; and
D) Information
for the purpose of designing a Phase II Hydrogeologic Investigation.
2) Specific Requirements
A) The regional hydrogeologic setting of the
unit shall be established by using material available from all possible
sources, including, but not limited to, the Illinois Scientific Surveys, the
Agency, other State and Federal organizations, water well drilling logs, and
previous investigations.
B) A
minimum of one continuously sampled boring shall be drilled on the site, as
close as feasible to the geographic center, to determine if the available
regional hydrogeologic setting information is accurate and to characterize the
site-specific hydrogeology to the extent specified by this phase of the
investigation. The boring shall extend at least 15.2 meters (50 feet) below the
bottom of the uppermost aquifer or through the full depth of the confining
layer below the uppermost aquifer, or to bedrock, if the bedrock is below the
upper most aquifer, whichever elevation is higher. The locations of any
additional borings, required under this subsection, may be chosen by the
investigator, but shall be sampled continuously.
d) Minimum Requirements for a
Phase II Investigation
1) Information to be
developed
Using the information developed in the Phase I survey, a
Phase II study shall be conducted to collect the site-specific information
listed below as needed to augment data collected during the Phase I
investigation and to prepare for the Phase III investigation:
A) Structural characteristics and
distribution of underlying strata including bedrock;
B) Chemical and physical properties
including, but not limited to, lithology, mineralogy, and hydraulic
characteristics of underlying strata including those below the uppermost
aquifer;
C) Soil characterisitics,
including soil types, distribution, geochemical and geophysical
characteristics;
D) The hydraulic
conductivities of the uppermost aquifer and all strata above it;
E) The vertical extent of the uppermost
aquifer;
F) The direction and rate
of groundwater flow.
2)
Specific Requirements
A) One boring shall be
located as close as feasible to the topographical high point, and another shall
be located as close as feasible to the topographical low point of the study
area.
B) At least one boring shall
be at or near each corner of the site. Where the property is irregularly shaped
the borings shall be located near the boundary in a pattern and spacing
necessary to obtain data over the entire study area.
C) Additional borings may be located at
intermediate points at locations and spacings necessary to establish the
continuity of the stratigraphic units.
D) Piezometers and groundwater monitoring
wells shall be established to determine the direction and flow characteristics
of the groundwater in all strata and extending down to the bottom of the
uppermost aquifer. Groundwater samples taken from such monitoring wells shall
be used to develop preliminary information needed for establishing background
concentrations in accordance with subsection (e)(1)(G).
E) Other methods may be utilized to confirm
or accumulate additional information. Such methods may be used only as a
supplement to, not in lieu of, site-specific boring information. Other methods
include, but are not limited to, geophysical well logs, geophysical surveys,
aerial photography, age dating, and test pits.
e) Minimum Standards for a Phase III
Investigation
1) Using the information
developed during the Phase I and Phase II Investigations, the operator shall
conduct a Phase III Investigation. This investigation shall be conducted to
collect or augment the site-specific information needed to carry out the
following:
A) Verification and reconciliation
of the information collected in the Phase I and II investigations;
B) Characterization of potential pathways for
contaminant migration;
C)
Correlation of stratigraphic units between borings;
D) Continuity of petrographic features
including, but not limited to, sorting, grain size distribution, cementation
and hydraulic conductivity;
E)
Identification of zones of potentially high hydraulic conductivity;
F) Identification of the confining layer, if
present;
G) Concentrations of
chemical constituents present in the groundwater below the unit, down to the
bottom of the uppermost aquifer, using a broad range of chemical analysis and
detection procedures such as, gas chromatographic and mass spectrometric
scanning. However, additional measurements and procedures shall be carried out
to establish background concentrations, in accordance with Section
811.320(d),
for:
i) Any constituent for which there is a
standard at 35 Ill. Adm. Code
620 established by the Board and which is
expected to appear in the leachate; and
ii) Any other constituent for which there is
no Board-established standard, but which is expected to appear in the leachate
at concentrations above PQL, as defined in Section
811.319(a)(4)(A)
for that constituent;
H) Characterization of the seasonal and
temporal, naturally and artificially induced, variations in groundwater quality
and groundwater flow; and
I)
Identification of unusual or unpredicted geologic features, including: fault
zones, fracture traces, facies changes, solution channels, buried stream
deposits, cross cutting structures and other geologic features that may affect
the ability of the operator to monitor the groundwater or predict the impact of
the disposal facility on groundwater.
2) In addition to the specific requirements
applicable to Phase I and II investigations, the operator shall collect
information needed to meet the minimum standards of a Phase III investigation
by using methods that may include, but not limited to excavation of test pits,
additional borings located at intermediate points between boreholes placed
during Phase I and II investigations, placement of piezometers and monitoring
wells, and institution of procedures for sampling and analysis.
f) The operator may conduct the
hydrogeologic investigation in any number of alternative ways provided that the
necessary information is collected in a systematic sequence consisting of at
least three phases that is equal to or superior to the investigation procedures
of this Section.