Mich. Admin. Code R. 299.4422 - Type II landfill design standards; leakage control criteria
Rule 422.
(1) A
landfill unit that is subject to the requirements of this rule shall be
located, designed, and constructed so that the risks posed by leakage through
the composite liner required by R 299.4421(1) are minimized. To do so, a
landfill unit shall be either of the following:
(a) A monitorable unit which is located over
a natural soil barrier and which is in compliance with subrule (2) of this rule
so as to restrict the migration of leakage from the unit.
(b) Designed with a double liner system which
is in compliance with subrule (3) of this rule and which is capable of
detecting and collecting leakage through the primary composite liner.
(2) To meet the leakage control
criteria of this rule, a type II landfill unit that is a monitorable unit may,
in addition to the composite liner required in R 299.4421, be located over a
natural soil barrier that is sufficient to prevent the migration of leakage
from the unit to the uppermost aquifer, for as long as use of the site is
restricted under section 11518 of the act, in the event of a failure of the
composite liner. Any of the following geologic conditions shall be in
compliance with location criteria if verified in accordance with the provisions
of R 299.4912:
(a) A natural soil barrier that
has a maximum demonstrated permeability of 1.0 x 10-7 cm/sec.
(b) A natural soil barrier that has a
thickness and permeability that is sufficient to prevent the migration of
leakage from the unit to the uppermost aquifer for that time period (TP)
specified in section 11518 of the act. An owner or operator may demonstrate the
sufficiency of the natural soil barrier by showing that the time of travel
(TOT) through the natural soil barrier is as follows:
TOT > (t) n/(k)
where: TOT = TP specified in section 11518 of the act
t = thickness of low permeability soil above the uppermost aquifer
k = maximum permeability of soil
n = soil porosity = 0.5, assuming total porosity equals effective porosity, unless demonstrated otherwise.
(c) A natural soil barrier underlain by an
uppermost aquifer that is sufficiently artesian to prevent the vertical
migration of contaminants from the site to the uppermost aquifer by advection
or dispersion. An owner or operator utilizing such a design shall demonstrate
that sufficient controls exist to maintain artesian conditions for that period
after closure specified by section 11518 of the act.
(d) Any combination of hydrogeology and
innovative design that minimizes the risk of leakage through the primary
composite liner at least as effectively as the conditions specified in
subdivision (a), (b), or (c) of this subrule.
(3) To meet the leakage control criteria of
this rule, a type II landfill unit may contain a double liner system or
equivalent system that is capable of detecting leakage through the primary
liner. A double liner system shall consist of all of the following components:
(a) A primary composite liner. For
monitorable units that have a secondary composite liner, the soil component of
the primary liner is optional on the portion of the side slope that is both of
the following:
(i) Of a slope greater than or
equal to 20%.
(ii) At a vertical
elevation not less than 5 feet above the bottom of the side slope.
(b) A secondary collection system
or leak detection system which is located immediately below the primary
composite liner and which is in compliance with the requirements of R
299.4424.
(c) A secondary composite
liner or any of the following alternate systems:
(i) A composite liner that uses, in place of
compacted soil, a natural soil barrier which has an equivalent combination of
permeability and thickness as 2 feet of 1.0 x 10-7 cm/sec compacted
soil.
(ii) A natural soil barrier
underlain by an uppermost aquifer that is sufficiently artesian to prevent the
vertical migration of contaminants from the site to the uppermost aquifer by
advection or dispersion. An owner or operator utilizing such a design shall
demonstrate that sufficient controls exist to maintain artesian conditions for
that period after closure specified by section 11518 of the act.
(iii) An alternate system which is approved
by the director and which prevents the migration of hazardous substances at
least as effectively as the other options specified in this subrule.
(4) Existing disposal
areas that permit natural soil barriers in place of liners shall be deemed to
be in compliance with the location criteria specified in subrule (2) of this
rule if the owner and operator verify the presence of such soil in accordance
with existing permits and licenses. Owners and operators of existing disposal
areas that were not previously permitted as natural clay sites may demonstrate
compliance with either the location criteria specified in subrule (2) of this
rule or the design criteria specified in subrule (3) of this rule. Owners and
operators shall submit certification that demonstrates compliance in accordance
with R 299.4912 and R 299.4921 with the operating license application for the
unit. An owner or operator may, at the owner's or operator's discretion, submit
either the information specified in R 299.4912 or revised engineering plans to
the solid waste control agency before or during construction of the unit. The
solid waste control agency shall approve or deny the plans within 90 days of
submittal.
Notes
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