Current through Bulletin 2024-06, March 15, 2024
(a) Performance
standard. The owner or operator of a CCR unit shall install a groundwater
monitoring system consists of a sufficient number of wells, installed at
appropriate locations and depths, to yield groundwater samples from the
uppermost aquifer that:
(1) Accurately
represent the quality of background groundwater that has not been affected by
leakage from a CCR unit. A determination of background quality may include
sampling of wells that are not hydraulically upgradient of the CCR management
area where:
(i) Hydrogeologic conditions do
not allow the owner or operator of the CCR unit to determine what wells are
hydraulically upgradient; or
(ii)
Sampling at other wells will provide an indication of background groundwater
quality that is as representative or more representative than that provided by
the upgradient wells; and
(2) Accurately represent the quality of
groundwater passing the waste boundary of the CCR unit. The downgradient
monitoring system shall be installed at the waste boundary that ensures
detection of groundwater contamination in the uppermost aquifer. All potential
contaminant pathways shall be monitored.
(b) The number, spacing, and depths of
monitoring systems shall be determined based upon site-specific technical
information that shall include thorough characterization of:
(1) Aquifer thickness, groundwater flow rate,
groundwater flow direction including seasonal and temporal fluctuations in
groundwater flow; and
(2) Saturated
and unsaturated geologic units and fill materials overlying the uppermost
aquifer, materials comprising the uppermost aquifer, and materials comprising
the confining unit defining the lower boundary of the uppermost aquifer,
including, but not limited to, thicknesses, stratigraphy, lithology, hydraulic
conductivities, porosities and effective porosities.
(c) The groundwater monitoring system shall
include the minimum number of monitoring wells necessary to meet the
performance standards specified in Subsection R315-319-91(a), based on the
site-specific information specified in Subsection R315-319-91(b). The
groundwater monitoring system shall contain:
(1) A minimum of one upgradient and three
downgradient monitoring wells; and
(2) Additional monitoring wells as necessary
to accurately represent the quality of background groundwater that has not been
affected by leakage from the CCR unit and the quality of groundwater passing
the waste boundary of the CCR unit.
(d) The owner or operator of multiple CCR
units may install a multiunit groundwater monitoring system instead of separate
groundwater monitoring systems for each CCR unit.
(1) The multiunit groundwater monitoring
system shall be equally as capable of detecting monitored constituents at the
waste boundary of the CCR unit as the individual groundwater monitoring system
specified in Subsections R315-319-91(a) through (c) for each CCR unit based on
the following factors:
(i) Number, spacing,
and orientation of each CCR unit;
(ii) Hydrogeologic setting;
(iii) Site history; and
(iv) Engineering design of the CCR
unit.
(2) If the owner
or operator elects to install a multiunit groundwater monitoring system, and if
the multiunit system includes at least one existing unlined CCR surface
impoundment as determined by Subsection R315-319-71(a), and if at any time
after October 19, 2015 the owner or operator determines in any sampling event
that the concentrations of one or more constituents listed in appendix IV to
Rule R315-319 are detected at statistically significant levels above the
groundwater protection standard established under Subsection R315-319-95(h) for
the multiunit system, then all unlined CCR surface impoundments comprising the
multiunit groundwater monitoring system are subject to the closure requirements
under Subsection R315-319-101(a) to retrofit or close.
(e) Monitoring wells shall be cased in a
manner that maintains the integrity of the monitoring well borehole. This
casing shall be screened or perforated and packed with gravel or sand, where
necessary, to enable collection of groundwater samples. The annular space,
i.e., the space between the borehole and well casing, above the sampling depth
shall be sealed to prevent contamination of samples and the groundwater.
(1) The owner or operator of the CCR unit
shall document and include in the operating record the design, installation,
development, and decommissioning of any monitoring wells, piezometers and other
measurement, sampling, and analytical devices. The qualified professional
engineer shall be given access to this documentation when completing the
groundwater monitoring system certification required under Subsection
R315-319-91(f).
(2) The monitoring
wells, piezometers, and other measurement, sampling, and analytical devices
shall be operated and maintained so that they perform to the design
specifications throughout the life of the monitoring program.
(f) The owner or operator shall
obtain a certification from a qualified professional engineer stating that the
groundwater monitoring system has been designed and constructed to meet the
requirements of Section R315-319-91. If the groundwater monitoring system
includes the minimum number of monitoring wells specified in Subsection
R315-319-91(c)(1), the certification shall document the basis supporting this
determination.
(g) The owner or
operator of the CCR unit shall comply with the recordkeeping requirements
specified in Subsection R315-319-105(h), the notification requirements
specified in Subsection R315-319-106(h), and the internet requirements
specified in Subsection R315-319-107(h).