Issue 3 - the Montana Secretary of State Website

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basing design requirements on a showing that a Class II landfill unit will not
contaminate the uppermost aquifer, which is the standard required by EPA in 40
CFR 258.40(a)(1). Therefore, the department has eliminated (1)(b).
Both existing ARM 17.50.506(2)(c) and 40 CFR 258.40(c)(3) require
consideration of the volume of leachate as a component for design approval.
The requirement in (3)(a), for accurate monitoring of leachate, measured to
within one centimeter, is necessary for proper evaluation of the effectiveness of an
approved liner. Metric units are commonly used in state rules and federal
regulations, and are appropriate here.
Subsection (3)(b), concerning minimum slope of a liner with a leachate
collection system, is equivalent to existing rule ARM 17.50.506(6)(b). See
Response to Comment No. 44. A 2% minimum slope for a leachate collection
system is necessary to cause leachate to flow to the collection point. This
requirement is contained in a comparable EPA guideline, Municipal Solid Waste
Disposal Facility Criteria Technical Manual, Subpart D Design Criteria, EPA 530-R-
93-017, page 152; and Sanitary Landfill Design and Operation, SW-65ts, page 9-35.
Therefore no findings are required by 75-10-107, MCA.
In response to the comment on (3)(b) concerning maximum slope for a liner,
the department has stricken the requirement that the maximum slope be limited to
33%. The maximum slope allowed will be determined by engineering submission
and review.
In response to the comment concerning (3)(c), the department has removed
(3)(c) because an owner or operator is required by New Rules XXXIII and XXXIV to
design a unit with an alternative liner to meet the ground water standards in Table 1
of New Rule XXXIII, and to obtain department approval of that design. The
department has determined that it is not appropriate to prescribe the elements of
that design; rather, it will review a design to determine whether it will meet the
standards. See Response to Comment No. 50.
The purpose of (3)(d) was to require that the design of a leachate removal
system, which could create a column of leachate in a pipe above a liner greater than
30 cm as it was being pumped away, had to take this increased head into account
to protect against leachate contamination of ground water due to stress caused by
the increased head on the liner. This is a necessary element of protecting ground
water at a landfill, and should be addressed in a design. This requirement is
contained in existing ARM 17.50.506(8)(c). However, in response to the comment,
the department is eliminating the specific requirement as unnecessary, because it
must be addressed as part of the design of the unit to show that ground water will
not be contaminated at the RPOC.
Concerning (6), CQA and CQC plans are necessary to ensure a landfill was
correctly constructed, and it is necessary for the department to review them to
determine whether they are adequate. Use of CQA and CQC plans is contained in
comparable EPA guidelines and the scientific literature. See, Quality Assurance
and Quality Control for Waste Containment Facilities, EPA/600/R-93/182, page 11,
which was expanded into a book by D.E. Daniel, Ph.D, P.E., and R.M. Koerner
Ph.D, P.E., entitled Waste Containment Facilities- Guidance for CQA and CQC of
Liner and Cover Systems (American Society of Civil Engineers 2d ed. 2007).
Research conducted by the Solid Waste Association of North America (SWANA)
Montana Administrative Register 3-2/11/10