[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]


-----------------------------------------------------------------------

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.

-----------------------------------------------------------------------

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]
BILLING CODE 6560-50-P