Current through Register Vol. 48, No. 38, September 20, 2024
a) All potential
sources of discharges to groundwater within the facility, including, but not
limited to, all waste disposal units and the leachate management system, shall
be identified and studied through a network of monitoring wells operated during
the active life of the unit and for the time after closure specified in
accordance with Section
811.319.
Monitoring wells designed and constructed as part of the monitoring network
shall be maintained along with records that include, but are not limited to,
exact well location, well size, type of well, the design and construction
practice used in its installation and well and screen depths.
b) Standards for the Location of Monitoring
Points
1) A network of monitoring points
shall be established at sufficient locations downgradient with respect to
groundwater flow and not excluding the downward direction, to detect any
discharge of contaminants from any part of a potential source of
discharge.
2) Monitoring wells
shall be located in stratigraphic horizons that could serve as contaminant
migration pathways.
3) Monitoring
wells shall be established as close to the potential source of discharge as
possible without interfering with the waste disposal operations, and within
half the distance from the edge of the potential source of discharge to the
edge of the zone of attenuation downgradient, with respect to groundwater flow,
from the source.
4) The network of
monitoring points of several potential sources of discharge within a single
facility may be combined into a single monitoring network, provided that
discharges from any part of all potential sources can be detected.
5) A minimum of at least one monitoring well
shall be established at the edge of the zone of attenuation and shall be
located downgradient with respect to groundwater flow and not excluding the
downward direction, from the unit. Such well or wells shall be used to monitor
any statistically significant increase in the concentration of any constituent,
in accordance with Section
811.320(e)
and shall be used for determining compliance with an applicable groundwater
quality standard of Section 811.320. An observed statistically significant
increase above the applicable groundwater quality standards of Section
811.320
in a well located at or beyond the compliance boundary shall constitute a
violation.
c) Maximum
Allowable Predicted Concentrations
The operator shall use the same calculation methods, data,
and assumptions as used in the groundwater impact assessment to predict the
concentration over time and space of all constituents chosen to be monitored in
accordance with Section
811.319
at all monitoring points. The predicted values shall be used to establish the
maximum allowable predicted concentrations (MAPC) at each monitoring point. The
MAPCs calculated in this subsection shall be applicable within the zone of
attenuation.
d) Standards
for Monitoring Well Design and Construction
1)
All monitoring wells shall be cased in a manner that maintains the integrity of
the bore hole. The casing material shall be inert so as not to affect the water
sample. Casing requiring solvent-cement type couplings shall not be
used.
2) Wells shall be screened to
allow sampling only at the desired interval. Annular space between the borehole
wall and well screen section shall be packed with gravel sized to avoid
clogging by the material in the zone being monitored. The slot size of the
screen shall be designed to minimize clogging. Screens shall be fabricated from
material expected to be inert with respect to the constituents of the
groundwater to be sampled.
3)
Annular space above the well screen section shall be sealed with a relatively
impermeable, expandable material such as a cement/bentonite grout, which does
not react with or in any way affect the sample, in order to prevent
contamination of samples and groundwater and avoid interconnections. The seal
shall extend to the highest known seasonal groundwater level.
4) The annular space shall be back-filled
with expanding cement grout from an elevation below the frost line and mounded
above the surface and sloped away from the casing so as to divert surface water
away.
5) The annular space between
the upper and lower seals and in the unsaturated zone may be back-filled with
uncontaminated cuttings.
6) All
wells shall be covered with vented caps and equipped with devices to protect
against tampering and damage.
7)
All wells shall be developed to allow free entry of water, minimize turbidity
of the sample, and minimize clogging.
8) The transmissivity of the zone surrounding
all well screens shall be established by field testing techniques.
9) Other sampling methods and well
construction techniques may be utilized if they provide equal or superior
performance to the requirements of this subsection.
e) Standards for Sample Collection and
Analysis
1) The groundwater monitoring program
shall include consistent sampling and analysis procedures to assure that
monitoring results can be relied upon to provide data representative of
groundwater quality in the zone being monitored.
2) The operator shall utilize procedures and
techniques to insure that collected samples are representative of the zone
being monitored and that prevent cross contamination of samples from other
monitoring wells or from other samples. At least 95 percent of a collected
sample shall consist of groundwater from the zone being monitored.
3) The operator shall establish a quality
assurance program that provides quantitative detection limits and the degree of
error for analysis of each chemical constituent.
4) The operator shall establish a sample
preservation and shipment procedure that maintains the reliability of the
sample collected for analysis.
5)
The operator shall institute a chain of custody procedure to prevent tampering
and contamination of the collected samples prior to completion of
analysis.
6) At a minimum, the
operator shall sample the following parameters at all wells at the time of
sample collection and immediately before filtering and preserving samples for
shipment:
A) The elevation of the water
table;
B) pH;
C) The temperature of the sample;
and
D) Specific
Conductance.
7) The
operator must measure the depth of the well below ground on an annual basis, at
wells that do not contain dedicated pumps. The operator must measure the depth
of the well below ground every 5 years, or whenever the pump is pulled, in
wells with dedicated pumps.
8) In
addition to the requirements of subsections (e)(1) through (e)(6), the
following requirements shall apply to MSWLF units:
A) Each time groundwater is sampled, an owner
or operator of a MSWLF unit shall:
i) Measure
the groundwater elevations in each well immediately prior to purging;
and
ii) Determine the rate and
direction of ground-water flow.
B) An owner or operator shall measure
groundwater elevations in wells which monitor the same waste management area
within a period of time short enough to avoid temporal variations in
groundwater flow which could preclude accurate determination of groundwater
flow rate and direction.
BOARD NOTE: Subsection (e)(7) is derived from
40 CFR
258.53(d)
(1992).
