Current through Register Vol. 47, No. 17, September 10, 2024
An owner or operator subject to this subpart must
establish an unsaturated zone monitoring program to discharge the following
responsibilities:
(a) The owner or
operator must monitor the soil and soil pore liquid to determine whether
hazardous constituents migrate out of the treatment zone.
(1) The Department will specify the hazardous
constituents to be monitored in the facility permit. The hazardous constituents
to be monitored are those specified under § 264.271(b).
(2) The Department may require monitoring for
principal hazardous constituents (PHCs) in lieu of the constituents specified
under § 264.271(b). PHCs are hazardous constituents contained in the
wastes to be applied at the unit that are the most difficult to treat,
considering the combined effects of degradation, transformation, and
immobilization. The Director will establish PHCs if he/she finds, based on
waste analyses, treatment demonstrations, or other data, that effective
degradation, transformation, or immobilization of the PHCs will assure
treatment of at least equivalent levels for the other hazardous constituents in
the wastes.
(b) The owner
or operator must install an unsaturated zone monitoring system that includes
soil monitoring using soil cores and soil-pore liquid monitoring using devices
such as lysimeters. The unsaturated zone monitoring system must consist of a
sufficient number of sampling points at appropriate locations and depths to
yield samples that:
(1) Represent the quality
of background soil-pore liquid quality and the chemical make-up of soil that
has not been affected by leakage from the treatment zone; and
(2) Indicate the quality of soil-pore liquid
and the chemical make-up of the soil below the treatment zone.
(c) The owner or operator must
establish a background value for each hazardous constituent to be monitored
under paragraph (a) of this section. The permit will specify the background
values for each constituent or specify the procedures to be used to calculate
the background values.
(1) Background soil
values may be based on a one-time sampling at a background plot having
characteristics similar to those of the treatment zone.
(2) Background soil-pore liquid values must
be based on at least quarterly sampling for one year at a background plot
having characteristics similar to those of the treatment zone.
(3) The owner or operator must express all
background values in a form necessary for the determination of statistically
significant increases under paragraph (f) of this section.
(4) In taking samples used in the
determination of all background values, the owner or operator must use an
unsaturated zone monitoring system that complies with paragraph (b)(1) of this
section.
(d) The owner or
operator must conduct soil monitoring and soil-pore liquid monitoring
immediately below the treatment zone. The Department will specify the frequency
and timing of soil and soil-pore liquid monitoring in the facility permit after
considering the frequency, timing, and rate of waste application, and the soil
permeability. The owner or operator must express the results of soil and
soil-pore liquid monitoring in a form necessary for the determination of
statistically significant increases under paragraph (f) of this
section.
(e) The owner or operator
must use consistent sampling and analysis procedures that are designed to
ensure sampling results that provide a reliable indication of soil-pore liquid
quality and the chemical make-up of the soil below the treatment zone. At a
minimum, the owner or operator must implement procedures and techniques for:
(1) Sample collection;
(2) Sample preservation and
shipment;
(3) Analytical
procedures; and
(4) Chain of
custody control.
(f) The
owner or operator must determine whether there is a statistically significant
change over background values for any hazardous constituent to be monitored
under paragraph (a) of this section below the treatment zone each time he/she
conducts soil monitoring and soil-pore liquid monitoring under paragraph (d) of
this section.
(1) In determining whether a
statistically significant increase has occurred, the owner or operator must
compare the value of each constituent, as determined under paragraph (d) of
this section, to the background value for that constituent according to the
statistical procedure specified in the facility permit under this
paragraph.
(2) The owner or
operator must determine whether there has been a statistically significant
increase below the treatment zone within a reasonable time period after
completion of sampling. The Department will specify that time period in the
facility permit after considering the complexity of the statistical test and
the availability of laboratory facilities to perform the analysis of soil and
soil-pore liquid samples.
(3) The
owner or operator must determine whether there is a statistically significant
increase below the treatment zone using a statistical procedure that provides
reasonable confidence that migration from the treatment zone will be
identified. The Director will specify a statistical procedure in the facility
permit that he/she finds:
(i) Is appropriate
for the distribution of the data used to establish background values;
and
(ii) Provides a reasonable
balance between the probability of falsely identifying migration from the
treatment zone and the probability of failing to identify real migration from
the treatment zone.
(g) If the owner or operator determines
pursuant to paragraph (f) of this section, that there is a statistically
significant increase of hazardous constituents below the treatment zone, he/she
must:
(1) Notify the Department of this
finding in writing within seven days. The notification must indicate what
constituents have shown statistically significant increases.
(2) Within 90 days, submit to the Department
an application for a permit modification to modify the operating practices at
the facility in order to maximize the success of degradation, transformation,
or immobilization processes in the treatment zone.
(h) If the owner or operator determines,
pursuant to paragraph (f) of this section, that there is a statistically
significant increase of hazardous constituents below the treatment zone, he/she
may demonstrate that a source other than regulated units caused the increase or
that the increase resulted from an error in sampling, analysis, or evaluation.
While the owner or operator may make a demonstration under this paragraph in
addition to, or in lieu of, submitting a permit modification application under
paragraph (g)(2) of this section, he/she is not relieved of the requirement to
submit a permit modification application within the time specified in paragraph
(g)(2) of this section unless the demonstration made under this paragraph
successfully shows that a source other than regulated units caused the increase
or that the increase resulted from an error in sampling, analysis, or
evaluation. In making a demonstration under this paragraph, the owner or
operator must:
(1) Notify the Department in
writing within seven days of determining a statistically significant increase
below the treatment zone that he/she intends to make a determination under this
paragraph;
(2) Within 90 days,
submit a report to the Department demonstrating that a source other than the
regulated units caused the increase or that the increase resulted from error in
sampling, analysis, or evaluation;
(3) Within 90 days, submit to the Department
an application for a permit modification to make any appropriate changes to the
unsaturated zone monitoring program at the facility; and
(4) Continue to monitor in accordance with
the unsaturated zone monitoring program established under this
section.
