(a) Study
The Administrator shall conduct a study of the extent to which the guidelines and criteria under this chapter (other than guidelines and criteria for facilities to which subchapter III applies) which are applicable to solid waste management and disposal facilities, including, but not limited to landfills and surface impoundments, are adequate to protect human health and the environment from ground water contamination. Such study shall include a detailed assessment of the degree to which the criteria under section 6907(a) of this title and the criteria under section 6944 of this title regarding monitoring, prevention of contamination, and remedial action are adequate to protect ground water and shall also include recommendation with respect to any additional enforcement authorities which the Administrator, in consultation with the Attorney General, deems necessary for such purposes.

(b) Report
Not later than thirty-six months after November 8, 1984, the Administrator shall submit a report to the Congress setting forth the results of the study required under this section, together with any recommendations made by the Administrator on the basis of such study.

(c) Revisions of guidelines and criteria

(1) In general
Not later than March 31, 1988, the Administrator shall promulgate revisions of the criteria promulgated under paragraph (1) of section 6944(a) of this title and under section 6907(a)(3) of this title for facilities that may receive hazardous household wastes or hazardous wastes from small quantity generators under section 6921(d) of this title. The criteria shall be those necessary to protect human health and the environment and may take into account the practicable capability of such facilities. At a minimum such revisions for facilities potentially receiving such wastes should require ground water monitoring as necessary to detect contamination, establish criteria for the acceptable location of new or existing facilities, and provide for corrective action as appropriate.

(2) Additional revisions
Subject to paragraph (3), the requirements of the criteria described in paragraph (1) relating to ground water monitoring shall not apply to an owner or operator of a new municipal solid waste landfill unit, an existing municipal solid waste landfill unit, or a lateral expansion of a municipal solid waste landfill unit, that disposes of less than 20 tons of municipal solid waste daily, based on an annual average, if—

(A) there is no evidence of ground water contamination from the municipal solid waste landfill unit or expansion; and

(B) the municipal solid waste landfill unit or expansion serves—

(i) a community that experiences an annual interruption of at least 3 consecutive months of surface transportation that prevents access to a regional waste management facility; or

(ii) a community that has no practicable waste management alternative and the landfill unit is located in an area that annually receives less than or equal to 25 inches of precipitation.

(3) Protection of ground water resources

(A) Monitoring requirement
A State may require ground water monitoring of a solid waste landfill unit that would otherwise be exempt under paragraph (2) if necessary to protect ground water resources and ensure compliance with a State ground water protection plan, where applicable.

(B) Methods
If a State requires ground water monitoring of a solid waste landfill unit under subparagraph (A), the State may allow the use of a method other than the use of ground water monitoring wells to detect a release of contamination from the unit.

(C) Corrective action
If a State finds a release from a solid waste landfill unit, the State shall require corrective action as appropriate.

(4) No-migration exemption

(A) In general
Ground water monitoring requirements may be suspended by the Director of an approved State for a landfill operator if the operator demonstrates that there is no potential for migration of hazardous constituents from the unit to the uppermost aquifer during the active life of the unit and the post-closure care period.

(B) Certification
A demonstration under subparagraph (A) shall be certified by a qualified ground-water scientist and approved by the Director of an approved State.

(C) Guidance
Not later than 6 months after March 26, 1996, the Administrator shall issue a guidance document to facilitate small community use of the no migration ¹ exemption under this paragraph.

(5) Alaska Native villages
Upon certification by the Governor of the State of Alaska that application of the requirements described in paragraph (1) to a solid waste landfill unit of a Native village (as defined in section 1602 of title 43) or unit that is located in or near a small, remote Alaska village would be infeasible, or would not be cost-effective, or is otherwise inappropriate because of the remote location of the unit, the State may exempt the unit from some or all of those requirements. This paragraph shall apply only to solid waste landfill units that dispose of less than 20 tons of municipal solid waste daily, based on an annual average.

(6) Further revisions of guidelines and criteria
Recognizing the unique circumstances of small communities, the Administrator shall, not later than two years after March 26, 1996, promulgate revisions to the guidelines and criteria promulgated under this subchapter to provide additional flexibility to approved States to allow landfills that receive 20 tons or less of municipal solid waste per day, based on an annual average, to use alternative frequencies of daily cover application, frequencies of methane gas monitoring, infiltration layers for final cover, and means for demonstrating financial assurance: Provided, That such alternative requirements take into account climatic and hydrogeologic conditions and are protective of human health and environment.