Section R. 299.4422 - Type II landfill design standards; leakage control criteriaRule 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.Mich. Admin. Code R. 299.4422