[Federal Register Volume 63, Number 238 (Friday, December 11, 1998)]
[Notices]
[Pages 68453-68455]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-32579]
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ENVIRONMENTAL PROTECTION AGENCY
[FRL-6195-5]
Salt River Pima-Maricopa Indian Community; Final Approval of an
Alternative Liner System Design and Use of Alternative Daily Cover
Material for the Salt River Municipal Solid Waste Landfill
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
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SUMMARY: The Environmental Protection Agency approves two requests by
the Salt River Pima-Maricopa Indian Community (``Community'') for
approval to use flexible standards at the Salt River Municipal Solid
Waste Landfill. The first approval allows the Community to install a
geosynthetic clay liner in place of a composite liner. The second
allows the Community to use a tarp system as cover in place of earthen
material.
Subtitle D of the Resource Conservation and Recovery Act (RCRA),
requires EPA to establish minimum federal criteria to ensure that
municipal solid waste landfills are designed and operated in a manner
that protects human health and the environment. Generally, these
criteria are technical standards that are ``self-implementing,''
meaning that the criteria are in effect as soon as they are published.
For many of these criteria, the regulations also establish a flexible
performance-based standard as an alternative to the self-implementing
regulations. Without EPA's approval, the flexible standards could not
be used at the Salt River Municipal Solid Waste Landfill. EPA's
approvals will allow the Salt River Municipal Solid Waste Landfill to
install a geosynthetic clay liner and to use a tarp system as cover at
the Landfill. This approval applies solely to the Salt River Municipal
Solid Waste Landfill located on Salt River Pima-Maricopa Indian
Reservation in Arizona.
DATES: Effective December 11, 1998.
FOR FURTHER INFORMATION CONTACT: US EPA Region 9, 75 Hawthorne Street,
San Francisco, California 94105, Attn: Ms. Susanna Trujillo, Mail Code
WST-7 telephone (415) 744-2099.
SUPPLEMENTARY INFORMATION:
A. Regulatory Background
Subtitle D of the Resource Conservation and Recovery Act (RCRA), as
amended by the Hazardous and Solid Waste Amendments of 1984 (HSWA), 42
U.S.C. 6941-6949a, governs the disposal of nonhazardous solid waste and
of small-quantity hazardous waste not regulated under Subtitle C of
RCRA. Subtitle D prohibits ``open dumping'' and EPA established
criteria for determining which solid waste facilities should be
classified as ``municipal solid waste landfills'' and which as ``open
dumps.'' Pursuant to HSWA, EPA added revised criteria to establish
minimum federal standards to ensure that municipal solid waste
landfills (MSWLF) are designed and operated in a manner that protects
human health and the environment. The Federal revised criteria are
codified at 40 CFR part 258. RCRA also requires states to implement
permit programs to ensure that MSWLF facilities comply with the revised
criteria (40 U.S.C. 6945(c)). EPA determines whether each state has
developed an adequate solid waste permitting program and ``approves''
those states. In states that do not develop an adequate program, the
regulations set forth in part 258 are self-implementing and apply to
owners and
[[Page 68454]]
operators of MSWLF units without additional EPA approval or review (40
CFR 258.1).
For many of the criteria, part 258 establishes a flexible
performance standard as an alternative to the self-implementing
regulation. The flexibility provided in the MSWLF criteria allows for
the consideration of site-specific conditions in designing and
operating a MSWLF at the lowest cost possible while ensuring protection
of human health and the environment. The flexible standard is not self-
implementing, and use of the alternative standard is generally approved
by the Director of an approved state. Part 258 does not currently
provide owners and operators of MSWLF units located in Indian Country
with a mechanism for obtaining approval of the flexible performance
standards.
Indian tribes are defined as ``municipalities'' under RCRA section
1004(13), 42 U.S.C. 6903. As a ``municipality,'' the tribe would seek
approval of design flexibility from the appropriate approved state.
However, states are generally precluded from enforcing their civil
regulatory programs in Indian Country absent an explicit Congressional
authorization. California v. Cabazon Band of Mission Indians, 480 US
202 (1987). Including tribes as part of section 1004(13) was a
definitional expedient, to avoid adding the phrase ``and Indian tribes
or tribal organizations or Alaska Native villages or organizations''
wherever the term ``municipality'' appeared. By this definition,
Congress did not intend to change the sovereign status of tribes for
purposes of RCRA. In Backcountry Against Dumps v. EPA, 100 F.3d 147,
151 (D.C. Cir. 1996), the District of Columbia Circuit Court determined
that the inclusion of Indian Tribes as ``municipalities'' ``does not
strip the tribe of its sovereign authority to govern its own affairs *
* * [the tribe has the authority] to create and enforce its own solid
waste management plan.'' RCRA does not grant this kind of regulatory
authority to municipalities.
Owners and operators of MSWLF units in Indian Country are not
subject to state authority and cannot obtain approval from the state
for the performance standards included in part 258. Yet, the Federal
revised criteria are silent as to the process by which MSWLF units in
Indian Country can apply for the alternate standards.
This site-specific provision allows the Salt River Pima-Maricopa
Indian Community (``Community''), an owner/operator of an MSWLF in
Indian Country, the same flexibility as owners and operators of MSWLF
units in approved states. EPA derives its authority to promulgate this
document from sections 4004, 4005, and 4010 of RCRA, 42 U.S.C. 6944,
6945, and 6949a. These sections provide the basis on which EPA
developed the criteria distinguishing open dumps from landfills and the
revised criteria in part 258. Nothing in these provisions limits EPA's
ability to issue site-specific criteria. In this instance, where the
existing part 258 regulations do not contain a process for approval of
the flexible performance standards for MSWLF units in Indian Country,
it is appropriate to issue a site-specific provision to supplement Part
258 and address this unique situation. The US District Court in the
District of South Dakota reviewed this issue directly and upheld EPA's
authority to issue a site-specific provision to provide design
flexibility under subtitle D of RCRA. (Yankton Sioux Tribe v. US EPA),
950 F. Supp. 1471 (D.S.D. 1996). The Yankton court determined that EPA
appropriately created an ``alternative mechanism'' to provide
flexibility to the relevant MSWLF in Indian Country. The US Court of
Appeals for the D.C. Circuit also supports EPA's authority to issue
such a site-specific provision under RCRA Subtitle D. (See Backcountry
Against Dumps v. EPA, 100 F.3d at 152 (1996)). For a description of the
suggested process used to apply for and approve flexibility requests in
Indian Country, see EPA draft guidance entitled ``Submitting Site-
Specific Rulemaking Requests for 40 CFR part 258.''
Prior to making this Final Determination, EPA provided opportunity
for public participation through a public comment period and a public
hearing. A document was published on May 8, 1998, (amended on May 27,
1998) describing EPA's tentative determination to approve the two
flexibility requests and announcing the public comment period and
public hearing. Notice was also published in two newspapers of general
circulation as well as the tribal newspaper. In addition, EPA sent
information on the tentative determination and public participation
opportunities directly to interested parties. August 5, 1998, was the
final date to submit public comments. EPA has not received either
written or verbal comments on the Tentative Determinations.
B. EPA's Final Determinations
1. Alternative Liner System Design (40 CFR 258.40)
The Salt River Landfill (Landfill) is located on 200 acres of
property east of Phoenix, Arizona. It is operated by the Salt River
Pima-Maricopa Indian Community and serves as a sanitary landfill for
the tri-city area of Mesa, Tempe, and Scottsdale, Arizona. Landfill
operations began in October 1993, and are expected to continue until at
least the year 2003. The landfill currently consists of three lined
cells and three undeveloped cells. The three operational cells are
lined with the composite liner prescribed by 40 CFR 258.40(b). On May
23, 1997, the Community submitted an application to the EPA requesting
approval to use a geosynthetic clay liner (GCL) in place of a composite
liner for the undeveloped cells of the Landfill.
The regulations at 40 CFR 258.40(b) require that the composite
liner have the following components: (1) A two-foot thick soil layer
with a maximum permeability of 1 x 10-7 cm/sec; (2) a
geomembrane layer with a minimum thickness of 60-mil if constructed out
of high density polyethylene, or 30-mil for other materials; and (3)
ensure protection of ground water.
The federal revised criteria do not specifically include a
procedure for EPA's tentative determination. However, EPA relied on the
requirements set forth in Sec. 258.40 as a guideline for analyzing the
Community's application.
Generally, Secs. 258.40(a)(1), (c), and (d) require the following:
The alternative liner design ensures that constituent
concentrations of the chemicals listed in Table 1 of the criteria will
not be exceeded in the uppermost aquifer at the relevant point of
compliance; and
The alternative liner design addresses the hydrogeologic
characteristics of the landfill site, climate, volume, and physical and
chemical characteristics of the leachate, and models potential
contaminant migration.
The reinforced GCL to be used at the Landfill consists of a layer
of pure sodium bentonite fixed between two layers of geotextiles. The
GCL is used to replace the two-foot thick soil layer required by 40 CFR
258.40(b) and forms a composite liner using a geomembrane. A
geomembrane is a polymeric material that cannot be penetrated by liquid
as long as it maintains its integrity.The bentonite used in the GCL is
an extremely absorbent, granular clay formed from volcanic ash. It
rapidly hydrates when exposed to liquid, such as water or leachate. As
the bentonite hydrates, it swells, providing a strong barrier layer.
Hydration of the bentonite is critical. Laboratory tests demonstrate
that dry, unconfined bentonite's
[[Page 68455]]
permeability is only approximately 1 x 10-6 cm/sec. When
saturated, the permeability of the GCL used at the Landfill is less
than 5 x 10-9. The GCL approved for the Landfill is
therefore less permeable than the prescriptive liner, provided that the
bentonite is well hydrated when it is installed. While the GCL is
thinner than a compacted soil liner at this level of permeability, the
alternative liner design ensures that the performance standards are
met. In addition to its low permeability, the GCL has many advantages
over the composite liner. The GCL is rolled out like carpet and is
quick and easy to install. It is cost effective, particularly in areas
where clay is not available. Because bentonite swells readily when
hydrated, it can repair itself if rips or holes occur. It is also more
resistant to cracking than compacted clay. The GCL is thin, yet strong.
It allows the Landfill to maximize its capacity while continuing to
protect ground water, but can also absorb a large amount of stress
without losing structural integrity.
The Salt River Pima-Maricopa Indian Community submitted site-
specific demonstration to the US EPA Solid Waste Program, showing that
its alternative liner design proposal meets the environmental
performance criteria set forth in 40 CFR part 258. 40. EPA staff
reviewed the Community's site-specific demonstration to determine if
the proposed alternative design meets the environmental performance
requirements and does not allow for degredation of the groundwater.
EPA's review determined that concentration values for parameters listed
in Table 1 of 40 CFR 258.40(a)(1) will not be exceeded in the uppermost
aquifer.
EPA's review also determined that groundwater models used in the
evaluation were appropriate and appropriately used and that results of
the computer modelling presented in the evaluation likely provide a
reasonable worst case estimate of the concentration of chemicals in the
groundwater.
EPA approves use of the GCL at the Landfill. Based on the
information submitted by the Community and as discussed above, EPA
determined that the alternative liner meets or exceeds the performance
standards set forth in Sec. 258.40(a)(1), (c), and (d).
2. Alternative Daily Cover Material (40 CFR 258.21)
The federal revised criteria requires that MSWLF units must use six
inches of earthen material to cover disposed solid waste each day.
Section 258.21(b) provides flexibility by allowing use of alternative
materials and an alternative thickness if control of disease carrying
insects and animals, fires, odours, blowing litter, and scavenging is
provided without presenting a threat to human health and the
environment.
On June 2, 1997, the Community submitted an application to the EPA
requesting approval to use any alternative daily cover material that
Arizona has approved for that state. These materials consist of tarps,
foams, chipped green waste, drinking water treatment residues, and
chipped tires. The Community subsequently restricted their current
application to the use of tarps as an alternative daily cover material.
The federal revised criteria does not specifically include a
procedure for EPA's tentative determination. However, EPA relied on the
requirements set forth in Sec. 258.21 as a guideline for analyzing the
Community's application. The Community proposes to use the Tarpomatic
tarping operation, consisting of a polypropylene tarp rolled over the
landfill material at the end of each business day and retrieved at the
beginning of the next business day. The Tarpomatic is a polypropylene
tarp that is automatically deployed and retrieved by machine. It is
fast, easy, and eliminates direct employee contact with waste. Field
tests and industry usage show that tarps meet the requirements of
Sec. 258.21. In addition, use of the tarping system rather than earthen
material extends the life of the landfill, reduces labor in covering
the waste, and saves landfill space. However, tarps cannot be used
during wind storms as the winds will pick up the tarp and the landfill
will not remain covered.
EPA approves use of a tarp at the Landfill. Based on the
information submitted by the Community and as discussed above, the
proposed alternative daily cover meets or exceeds the performance
standards set forth in Sec. 258.21(b).
Authority: This notice is issued under the authority of sections
2002, 4004, 4005, and 4010 of the Solid Waste Disposal Act as
amended, 42 U.S.C. 6912, 6944, 6945, and 6949a. The Regional
Administrator is making this decision in accordance with EPA
Delegations Manual No. 8-47 (October 8, 1993).
EPA approves the applications by the Salt River Pima-Maricopa
Indian Community to use an alternative liner system design and an
alternative daily cover material for the Salt River Municipal Solid
Waste Landfill.
Dated: November 20, 1998.
Felicia Marcus,
Regional Administrator, Region 9.
[FR Doc. 98-32579 Filed 12-10-98; 8:45 am]
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