(1) A groundwater
monitoring system shall be capable of yielding groundwater samples for analysis
and shall consist of all of the following:
(a)
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 shall be sufficient to yield
groundwater samples that are all of the following:
1. Representative of background groundwater
quality in the uppermost aquifer near the facility.
2. Not affected by the facility.
(b) Monitoring wells (at least 3)
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 shall 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.
(c) The facility owner or operator may
demonstrate that an alternate hydraulically downgradient monitoring well
location will meet all of the following criteria. The demonstration shall be in
writing and kept at the facility. The demonstration shall be certified by a
qualified groundwater scientist and establish that all of the following apply:
1. An existing physical obstacle prevents
monitoring well installation at the hydraulically downgradient limit of the
waste management area.
2. The
selected alternate downgradient location is as close to the limit of the waste
management area as practical.
3.
The location ensures detection that, given the alternate location, is 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.
4. Lateral
expansion, new or replacement units are not eligible for an alternate
downgradient location under this paragraph.
(2) 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.
(a) In the case of a facility consisting of
only one surface impoundment or landfill, the waste boundary (perimeter)
describes the waste management area.
(b) In the case of a facility consisting of
more than one surface impoundment or landfill, an imaginary boundary line which
circumscribes the several waste management components describes the waste
management area.
(3) All
monitoring wells shall be cased in a manner that maintains the integrity of the
monitoring well bore hole. This casing shall 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 shall be
sealed with a suitable material (e.g., cement grout or bentonite slurry) to
prevent contamination of samples and the groundwater.
