Current through Register Vol. 48, No. 38, September 20, 2024
a)
A groundwater monitoring system must be capable of yielding groundwater samples
for analysis and must consist of the following components:
1) Monitoring wells (at least one) installed
hydraulically upgradient (i.e., in the direction of increasing static head)
from the limit of the waste management area. Their number, locations, and
depths must be sufficient to yield groundwater samples that fulfill both of the
following requirements:
A) The samples are
representative of background groundwater quality in the uppermost aquifer near
the facility; and
B) The samples
are not affected by the facility; and
2) Monitoring wells (at least three)
installed hydraulically downgradient (i.e., in the direction of decreasing
static head) at the limit of the waste management area. Their number,
locations, and depths must ensure that they immediately detect any
statistically significant amounts of hazardous waste or hazardous waste
constituents that migrate from the waste management area to the uppermost
aquifer.
b) Separate
monitoring systems for each waste management component of a facility are not
required provided that provisions for sampling upgradient and downgradient
water quality will detect any discharge from the waste management area.
1) In the case of a facility consisting of
only one surface impoundment, landfill, or land treatment area, the waste
management area is described by the waste boundary (perimeter).
2) In the case of a facility consisting of
more than one surface impoundment, landfill, or land treatment area, the waste
management area is described by the imaginary boundary line that circumscribes
the several waste management components.
3) The facility owner or operator may
demonstrate that an alternate hydraulically downgradient monitoring well
location will meet the criteria outlined below. The demonstration must be in
writing and kept at the facility. The demonstration must be certified by a
qualified groundwater scientist and establish each of the following:
A) That an existing physical obstacle
prevents monitoring well installation at the hydraulically downgradient limit
of the waste management area.
B)
That the selected alternate downgradient location is as close to the limit of
the waste management area as practical.
C) That the alternate location ensures
detection as early as possible of any statistically significant amounts of
hazardous waste or hazardous waste constituents that migrate from the waste
management area to the uppermost aquifer.
D) Lateral expansion, new, or replacement
units are not eligible for an alternate downgradient location under this
subsection (b)(3).
c) All monitoring wells must be cased in a
manner that maintains the integrity of the monitoring well bore hole. This
casing must be screened or perforated and packed with gravel or sand where
necessary to enable sample collection at depths where appropriate aquifer flow
zones exist. The annular space (i.e., the space between the bore hole and well
casing) above the sampling depth must be sealed with a suitable material (e.g.,
cement grout or bentonite slurry) to prevent contamination of samples and the
groundwater.
