Mich. Admin. Code R. 299.4906 - Landfill groundwater monitoring; systems
Rule 906.
(1) A
landfill groundwater monitoring system shall be installed and shall consist of
a sufficient number of wells, installed at appropriate locations and depths, to
yield groundwater samples from the uppermost aquifer that are in compliance
with both of the following provisions:
(a)
Represent the quality of background groundwater that has not been affected by
leakage from a unit. A determination of background groundwater quality may
include sampling of wells that are not hydraulically upgradient of the waste
management area where either of the following conditions exist:
(i) Hydrogeologic conditions do not allow the
owner or operator to determine that wells are hydraulically
upgradient.
(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. In cases where the director has approved the sampling of wells that are
not upgradient to determine background groundwater quality, the owner and
operator shall maintain 1 or more upgradient wells to verify that the alternate
wells are as or more representative.
(b) Represent the quality of groundwater
hydraulically downgradient of the solid waste boundary and ensure detection of
groundwater contamination in the uppermost aquifer and other groundwater
specified by the director. When physical obstacles preclude the installation of
groundwater monitoring wells at the solid waste boundary, the downgradient
monitoring system shall be installed at the closest practicable distance
hydraulically downgradient from the solid waste boundary to ensure detection of
groundwater contamination in the uppermost aquifer and other groundwater
specified by the director.
(2) The director may approve a multiunit
groundwater monitoring system instead of separate groundwater monitoring
systems for each type II landfill unit when the facility has several discrete
units, if both of the following conditions are met:
(a) Groundwater monitoring wells are not more
than 150 meters from the solid waste boundary of each unit and are located on
land that is owned by the owner of the unit.
(b) The multiunit groundwater monitoring
system is in compliance with the requirements of subrule (1) of this rule and
will be as protective of human health and the environment as individual
monitoring systems for each unit, based on the following factors:
(i) The number, spacing, and orientation of
the units.
(ii) The hydrogeologic
setting.
(iii) The site
history.
(iv) The engineering
design of the units.
(v) The type
of waste accepted at the units.
(3) Monitoring wells shall be cased in a
manner that maintains the integrity of the monitoring well bore hole. The
casing shall be screened or perforated and packed with gravel or sand, where
necessary, to enable the collecting of groundwater samples. The annular space
between the bore hole and well casing above the sampling depth shall be sealed
to prevent the contamination of samples and the groundwater.
(4) The owner and operator shall notify the
director that documentation of the design, installation, development, and
decommission of any monitoring wells, piezometers, and other measurement,
sampling, and analytical devices has been placed in the operating
record.
(5) All monitoring wells,
piezometers, and other measurement, sampling, and analytical devices shall be
designed, operated, and maintained so that they perform to design
specifications throughout the life of the monitoring program.
(6) All monitoring wells shall be designed to
minimize the time that is necessary to recharge the well, given the hydraulic
conductivity of the aquifer.
(7)
The number, spacing, and depths of monitoring systems shall be in compliance
with all of the following provisions:
(a) Be
based upon site-specific technical information, including a thorough
characterization of both of the following:
(i)
The uppermost aquifer, including all of the following information:
(A) Aquifer thickness.
(B) Groundwater flow rate.
(C) Groundwater flow direction, including
seasonal and temporal fluctuations in groundwater flow.
(ii) Saturated and unsaturated geologic units
and fill materials that overlie the uppermost aquifer, materials that comprise
the uppermost aquifer, and materials that comprise the confining unit defining
the lower boundary of the uppermost aquifer, including all of the following
information:
(A) Thicknesses.
(B) Stratigraphy.
(C) Lithology.
(D) Hydraulic conductivities.
(E) Porosities.
(F) Effective porosities.
(b) Be certified by a
geologist.
(c) Be approved by the
director. Within 14 days of the approval, the owner or operator shall notify
the director that the certification and approval have been placed in the
operating record.
(8)
All wells shall be clearly labeled and shall be properly vented, capped, and
locked when not in use. All wells shall be visible throughout the
year.
(9) The owner or operator
shall not undertake well replacement, plugging, abandonment, or repair without
the approval of the director or his or her designee.
Notes
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