`[Federal Register Volume 60, Number 7 (Wednesday, January 11, 1995)]
[Rules and Regulations]
[Pages 2854-2871]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-546]


      

[[Page 2853]]


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Part IV





Environmental Protection Agency





_______________________________________________________________________



40 CFR Part 192



Groundwater Standards for Remedial Actions at Inactive Uranium 
Processing Sites; Final Rule

  Federal Register / Vol. 60, No. 7 / Wednesday, January 11, 1995 / 
Rules and Regulations  

[[Page 2854]]



ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 192

[FRL-3510-1]
RIN 2060-AC03


Groundwater Standards for Remedial Actions at Inactive Uranium 
Processing Sites

AGENCY: Environmental Protection Agency.

ACTION: Final rule.

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

SUMMARY: The Environmental Protection Agency is issuing final 
regulations to correct and prevent contamination of groundwater beneath 
and in the vicinity of inactive uranium processing sites by uranium 
tailings. EPA issued regulations (40 CFR part 192, subparts A, B, and 
C) for cleanup and disposal of tailings from these sites on January 5, 
1983. These new regulations replace existing provisions at 40 CFR 
192.20(a)(2) and (3) that were remanded by the U.S. Court of Appeals 
for the Tenth Circuit on September 3, 1985. They are promulgated 
pursuant to Section 275 of the Atomic Energy Act, as amended by Section 
206 of the Uranium Mill Tailings Radiation Control Act of 1978 (Public 
Law 95-604).
    The regulations apply to tailings at the 24 locations that qualify 
for remedial action under Title I of Public Law 95-604. They provide 
that tailings must be stabilized and controlled in a manner that 
permanently eliminates or minimizes contamination of groundwater 
beneath stabilized tailings, so as to protect human health and the 
environment. They also provide for cleanup of contamination that 
occurred before the tailings are stabilized.

EFFECTIVE DATE: February 10, 1995.

ADDRESSES: Background Documents. A report (``Groundwater Protection 
Standards for Inactive Uranium Tailings Sites, Background Information 
for Final Rule,'' EPA 520/1-88-023) has been prepared in support of 
these regulations. Another report (``Groundwater Protection Standards 
for Inactive Uranium Tailings Sites, Response to Comments,'' EPA 520/1-
88-055) contains the detailed responses of the Environmental Protection 
Agency to comments on the standard by the reviewing public. Single 
copies of these documents may be obtained from the Program Management 
Office (6601J), Office of Radiation and Indoor Air, U.S. Environmental 
Protection Agency, Washington, DC 20460; (202) 233-9354.
    Docket. Docket Number R-87-01 contains the rulemaking record. The 
docket is available for public inspection between 8 a.m.-4 p.m., 
weekdays, at EPA's Central Docket Section (LE-131), Room M-1500, 401 M 
Street SW., Washington, DC 20460. A reasonable fee may be charged for 
copying.

FOR FURTHER INFORMATION CONTACT: Allan C.B. Richardson, Criteria and 
Standards Division (6602J), Office of Radiation and Indoor Air, U.S. 
Environmental Protection Agency, Washington, DC 20460; telephone (202) 
233-9213.

SUPPLEMENTARY INFORMATION:

I. Introduction

    On November 8, 1978, Congress enacted the Uranium Mill Tailings 
Radiation Control Act of 1978 (henceforth called ``UMTRCA''). In 
UMTRCA, Congress found that uranium mill tailings ``* * * may pose a 
potential and significant radiation health hazard to the public, and * 
* * that every reasonable effort should be made to provide for 
stabilization, disposal, and control in a safe and environmentally 
sound manner of such tailings in order to prevent or minimize radon 
diffusion into the environment and to prevent or minimize other 
environmental hazards from such tailings.'' The Act directs the 
Administrator of the Environmental Protection Agency (EPA) to set ``* * 
* standards of general application for the protection of the public 
health, safety, and the environment * * *'' to govern this process of 
stabilization, disposal, and control.
    UMTRCA directs the Department of Energy (DOE) to conduct such 
remedial actions at the inactive uranium processing sites as will 
insure compliance with the standards established by EPA. This remedial 
action is to be selected and performed with the concurrence of the 
Nuclear Regulatory Commission (NRC). Upon completion of the remedial 
action program, the depository sites will remain in the custody of the 
Federal government under an NRC license.
    The standards apply to residual radioactive material at the 24 
processing sites designated, as provided in the Act, by DOE. Residual 
radioactive material is defined as any wastes which DOE determine to be 
radioactive, either in the form of tailings resulting from the 
processing of ores for the extraction of uranium and other valuable 
constituents of the ores, or in other forms which relate to such 
processing, such as sludges and captured contaminated water from these 
sites. (Additional wastes that do not meet this definition may be 
subject to regulation as hazardous waste under the Solid Waste Disposal 
Act (SWDA) as amended by the Resource Conservation and Recovery Act of 
1976 (RCRA).)
    Standards are required for two types of remedial actions: disposal 
and cleanup of residual radioactive material. Disposal is here used to 
mean the operation that places tailings in a permanent condition which 
will minimize risk of harmful effects to the health of people and harm 
to the environment. Cleanup is the operation that eliminates, or 
reduces to acceptable levels, the potential health and environmental 
consequences of tailings or their constituents that have been dispersed 
from tailings piles or disposal areas by natural forces or by human 
activity, through removal of residual radioactive materials from land, 
buildings, and groundwater.
    On January 5, 1983, EPA promulgated final standards for the 
disposal and cleanup of the inactive mill tailings sites under UMTRCA 
(48 FR 590). These standards were challenged in the Tenth Circuit Court 
of Appeals by several parties (Case Nos. 83-1014, 83-1041, 83-1206, and 
83-1300). On September 3, 1985, the court dismissed all challenges 
except one: it set aside the groundwater provisions of the regulations 
at 40 CFR 192.20(a)(2) and (3) and remanded them to EPA ``* * * to 
treat these toxic chemicals that pose a groundwater risk as it did in 
the active mill site regulations.'' On September 24, 1987, EPA proposed 
new standards to replace those remanded. A public hearing was held in 
Durango, Colorado, on October 29, 1987. In response to requests from 
several commenters at the public hearing and a later request by the 
American Mining Congress, the public record for comments on the 
proposed standard was not closed until January 29, 1988. With this 
notice, EPA is establishing final standards to replace those set aside.

II. Summary of Background Information

    Beginning in the 1940's, the U.S. Government purchased large 
quantities of uranium for defense purposes. As a result, large piles of 
tailings were created by the uranium milling industry. Tailings piles 
pose a hazard to public health and the environment because they contain 
radioactive and toxic constituents which emanate radon to the 
atmosphere and may leach into groundwater. Tailings, which are a sand-
like material, have also been removed from tailings piles in the past 
for use in construction and for soil

[[Page 2855]]

conditioning. These uses are inappropriate, because the radioactive and 
toxic constituents of tailings may elevate indoor radon levels, expose 
people to gamma radiation, and leach into ground and surface waters.
    Most of the mills are now inactive and many of the sites were 
abandoned. These abandoned sites are being remediated under Title I of 
UMTRCA. Congress designated 22 specific inactive sites in Title I of 
UMTRCA, and the DOE subsequently added two more. Most remaining uranium 
mill tailings sites are regulated by the NRC or States and will be 
reclamated under Title II of UMTRCA. (DOE also owns one inactive site 
at Monticello, Utah, that is not included under UMTRCA). The Title I 
sites are located in the West, predominantly in arid areas, except for 
a single site at Canonsburg, Pennsylvania. Before disposal operations 
began, tailings piles at the inactive sites ranged in area from 5 to 
150 acres and in height from only a few feet to as much as 230 feet. 
The amount at each site ranges from residual contamination to 2.7 
million tons of tailings. The 24 designated Title I sites combined 
contain about 26 million tons of tailings covering a total of about 
1000 acres.
    Under the provisions of Title I of UMTRCA, the DOE is responsible 
for the disposal of tailings at these sites, which will then be 
licensed to DOE by NRC for long term surveillance and maintenance, 
following NRC approval of the remediation. In addition, tailings that 
were dispersed from the piles by natural forces or that have been 
removed for use in or around buildings or on land are being retrieved 
and replaced on the tailings piles prior to their disposal.
    UMTRCA, as originally enacted, required that DOE complete all these 
remedial actions within 7 years of the effective date of EPA's 
standards, that is, by March 5, 1990. At the end of 1993 disposal 
actions had been completed at ten sites: Canonsburg, Pennsylvania, one 
of two sites in areas of high precipitation (Falls City, Texas is the 
other); Shiprock, New Mexico; Salt Lake City, Utah; Lakeview, Oregon; 
Green River, Utah; Spook and Riverton, Wyoming; Lowman, Idaho; Tuba 
City, Arizona; and Durango, Colorado. Disposal actions were well 
advanced at eight other sites: Rifle (two piles), Grand Junction, and 
Gunnison, Colorado; Monument Valley, Arizona; Mexican Hat, Utah; Falls 
City, Texas; and Ambrosia Lake, New Mexico. The remaining sites are in 
the advanced stages of planning and should be under construction within 
the next two years. In view of the rate of progress with remedial work, 
Congress in 1988 extended the completion date for disposal and most 
cleanup activities until September 30, 1994, and provided further ``* * 
* that the authority of the Secretary to perform groundwater 
restoration activities under this title is without limitation.'' 
(Uranium Mill Tailings Remedial Action Amendments Act of 1988, P.L. 
100-616, November 5, 1988; 42 U.S.C. 7916). Section 1031 of the Energy 
Policy Act of 1992 further extended the completion date for UMTRCA 
surface stabilization (disposal) activities to September 30, 1996.
    The most important hazardous constituent of uranium mill tailings 
is radium, which is radioactive. Other potentially hazardous substances 
in tailings piles include arsenic, molybdenum, selenium, uranium, and, 
usually in lesser amounts, a variety of other toxic substances. The 
concentrations of these materials in tailings vary from pile to pile, 
ranging from 2 to more than 100 times local background soil 
concentrations. A variety of organics is also known to have been used 
at these sites.
    Exposure to radioactive and toxic substances may cause cancer and 
other diseases, as well as genetic damage and teratogenic effects. 
Tailings pose a risk to health because: (1) Radium in tailings decays 
into radon, a gaseous radioactive element which is easily transported 
in air and the radioactive decay products of which may lodge in the 
lungs; (2) individuals may be directly exposed to gamma radiation from 
the radioactivity in tailings; and (3) radioactive and toxic substances 
from tailings may leach into water and then be ingested with food or 
water, or inhaled following aeration. It is the last of these hazards 
that is primarily addressed here. (Although radon from radium in 
groundwater is unlikely to pose a substantial hazard at these 
locations, these standards also address that potential hazard.) The 
other hazards are covered by existing provisions of 40 CFR part 192.
    EPA's technical analysis was based on detailed reports for 14 of 
the 24 inactive uranium mill tailings sites that had been developed by 
late 1988 for the Department of Energy by its contractors. Preliminary 
data for the balance of the sites were also examined. Those data showed 
that the volumes of contaminated water in aquifers at the 24 sites 
range from a few tens of millions of gallons to 4 billion gallons. In a 
few instances mill effluent was apparently the sole source of this 
groundwater. Each of the 14 sites examined in detail had at least some 
groundwater contamination beneath and/or beyond the site. In some cases 
the groundwater upgradient of the pile already exceeded EPA drinking 
water standards for one or more contaminants due to mineralization 
sources or due to anthropogenic sources other than the uranium milling 
activities, thus making it unsuitable for use as drinking water without 
treatment and, in some extreme cases, for most other purposes before it 
was contaminated by effluent from the mill. Some contaminants from the 
tailings piles are moving offsite quickly and others are moving slowly. 
The time for natural flushing of the contaminated portions of these 
aquifers was estimated to vary from a couple of years to many hundreds 
of years. Active restoration was estimated to take from less than 5 
years at most sites to approximately 50 years at one site.
    DOE currently estimates that there is approximately 4.7 billion 
gallons of contaminated water, but this estimate does not include all 
sites. One site, Lowman, Idaho, shows no sign of contamination related 
to the processing activities, while the site with the largest amount of 
contamination, Monument Valley, Arizona, has an estimated 0.75 billion 
gallons of contaminated water. The DOE estimate does not include those 
sites where current assessments indicate that supplemental standards 
should be applied, because contamination at these sites has been hard 
to quantify.
    Contaminants that have been identified in the groundwater 
downgradient from a majority of the sites include uranium, sulfate, 
iron, manganese, nitrate, chloride, molybdenum, selenium, and total 
dissolved solids. Radium, arsenic, fluoride, sulfide, chromium, 
cadmium, vanadium, lead, and copper have also been found in the 
groundwater at one or more sites.
    UMTRCA requires that the standards established under Title I 
provide protection that is consistent, to the maximum extent 
practicable, with the requirements of RCRA. In this regard, regulations 
established by EPA for hazardous waste disposal sites under RCRA 
provide for the specification of a groundwater protection standard for 
each waste management area in the facility permit (see 40 CFR part 264, 
subpart F). The groundwater protection standard includes a list of 
specific hazardous constituents relevant to each waste management area, 
a concentration limit for each hazardous constituent, the point of 
compliance, and the compliance period. The subpart F regulations 
specify that the concentration limits may be set at

[[Page 2856]]

general numerical limits (maximum concentration limits (MCLs)) for some 
hazardous constituents or at their background level in groundwater 
unless alternate concentration limits (ACLs) are requested and 
approved. ACLs may be requested based upon data which would support a 
determination that, if the ACL is satisfied, the constituent would not 
present a current or potential threat to human health and the 
environment. This standard incorporates many of these provisions into 
the regulations for the Title I sites.

III. Changes and Clarifications in Response to Comments

    These final standards modify and clarify some of the provisions of 
the proposed standards as a result of information and views submitted 
during the comment period and at the public hearing. EPA received many 
comments on the proposed standards. Twenty-three letters were received 
and eight individuals testified at the public hearing. Comments were 
submitted from private citizens, public interest groups, members of the 
scientific community, and representatives of industry and of State and 
Federal agencies. EPA has carefully reviewed and considered these 
comments in preparing its detailed Response to Comments and the final 
Background Information Document and in developing the final standards. 
EPA's responses to major comments are summarized below.

Uranium Concentration Limit

    Several commenters pointed out that the Agency used inappropriate 
dose conversion values (nonstochastic) for uranium and radium (instead 
of the more appropriate stochastic values) in developing the proposed 
concentration limit for uranium. These comments were correct. We have 
reevaluated the risks associated with ingestion of uranium, using 
current risk factors for radiocarcinogenicity of uranium, and have also 
considered the chemical toxicity of uranium. We have concluded that the 
level proposed, 30 pCi/liter, provides an adequate margin of safety 
against both carcinogenic and toxic effects of uranium, and that the 
level should be expressed in terms of the concentration of 
radioactivity, because it is related to the principal health risk, and 
can accommodate different levels of radioactive disequilibrium between 
uranium-234 and uranium-238.
    EPA's Office of Groundwater and Drinking Water has also examined 
these factors, and, on July 18, 1991, proposed the MCL for uranium in 
drinking water be set at a chemical concentration comparable to the 
limit on radioactivity promulgated in this regulation. Should the MCL 
for drinking water, as finally promulgated, provide a level of health 
protection different from that provided by the limit in this 
regulation, EPA will reconsider the limit at that time. On the basis of 
the above considerations, the limit for uranium has been established at 
30 pCi/liter for this regulation.

Molybdenum Concentration Limit

    Several reviewers objected to the proposed inclusion of a limit on 
molybdenum. They pointed out that EPA has not established a drinking 
water standard for this element. While this is true, the drinking water 
regulations also make provision for health advisories in the case of 
contaminants that are problems only in special situations. Molybdenum 
in the vicinity of uranium mill tailings is such a special case. 
Uranium mill tailings often contain high concentrations of molybdenum 
that can leach into groundwater in concentrations that may cause toxic 
effects in humans and cattle. This rule therefore continues to contain 
a limit on the concentration of molybdenum in groundwater. The value 
chosen remains the same as that proposed, as discussed in Section IV 
below.

Other Groundwater Limits

    These groundwater limits incorporate MCLs issued under the Safe 
Drinking Water Act (SDWA) (42 USC 300f, et seq.) and in effect for 
sites regulated under RCRA from the time these limits were proposed on 
September 24, 1987, to the present. However, on January 30, 1991, EPA 
issued new MCLs for some of the inorganic constituents included in the 
present limits, and proposed new drinking water standards for 
radioactive constituents were published on July 18, 1991 (56 FR 3526 
and 33050). Following publication of final drinking water standards for 
radioactive constituents, EPA will consider whether the benefits and 
costs implied by differences between these limits and the new drinking 
water standards warrant proposing to incorporate the new values into 
both the Title I and the Title II limits for groundwater.

Application of These Regulations to Vicinity Properties

    Several commenters questioned the wisdom of applying these 
regulations to vicinity properties. (Vicinity properties are real 
properties or improvements in the vicinity of a tailings pile that are 
determined by DOE, in consultation with the NRC, to be contaminated 
with residual radioactive materials.) They indicated that if the 
portion of the proposed rule requiring detailed assessment and 
monitoring were applied to all vicinity properties, it would greatly 
expand the cost of the program without providing additional benefits. 
Since only a few vicinity properties contain sufficient tailings to 
constitute a significant threat of groundwater contamination, we have 
concluded that detailed assessment and monitoring, followed by 
identification of listed constituents and groundwater standards, is not 
required at all vicinity properties. It is necessary only at those 
vicinity properties with a significant potential for groundwater 
contamination, as determined by the DOE (with the concurrence of NRC) 
using factors such as those in EPA's RCRA Facility Assessment Guidance 
document. It should be noted that this modification applies to the 
requirement for detailed assessment and monitoring only; the standards 
for cleanup of groundwater contamination are not changed. In addition, 
we note that the minimal quantities of residual radioactive materials 
left behind at vicinity properties after compliance with subpart B do 
not constitute disposal sites under subpart A.

Application of State Regulations to These Sites

    Some commenters expressed the view that these regulations should 
require consistency with State laws and regulations. EPA's regulations 
for licensed mill tailings sites under Title II of this Act do not 
contain such a provision. (Although NRC Agreement States may, under the 
Atomic Energy Act, adopt standards which ``* * * are equivalent to the 
extent practicable or more stringent * * *,'' they have not done so 
under UMTRCA.) We have decided that decisions regarding consistency 
with State laws and regulations should be made by DOE in consultation 
with the States, as provided by Section 103 of the Act. In making these 
decisions in cases where an approved Wellhead Protection Area, under 
the Safe Drinking Water Act, is associated with the site, however, DOE 
must comply with the provisions of that program, unless an exemption is 
granted by the President of the United States. In addition, 
contamination on the site that is not covered by UMTRCA (because it is 
not related to the processing operation) may be covered by Federal or 
State RCRA programs.

Application of Institutional Controls During an Extended Remedial 
Period

    Several comments were received concerning the effectiveness, 
reliability,

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and enforceability of institutional controls to be applied during a 
remedial period that has been extended to take advantage of natural 
flushing. EPA recognizes that some institutional controls, such as 
advisories or signs, although desirable as secondary measures, are not 
appropriate as primary measures for preventing human exposure to 
contaminated water. For this reason, the regulations permit 
institutional controls to be used in place of remediation only when DOE 
is able to ensure their effectiveness will be maintained during their 
use. The standards require that institutional controls ``* * * 
effectively protect public health and the environment and satisfy 
beneficial uses of groundwater * * *'' during their period of 
application. In this regard, we note that tribal, state, and local 
governments can also play a key role in assuring the effectiveness of 
institutional controls. In some cases this may be effected through 
changes in tribal, state, or local laws to ensure the enforceability of 
institutional controls by the administrative or judicial branches of 
government entities. One State indicated that some institutional 
controls, such as deed restrictions, should not be viewed as 
restrictions since they do not empower any agency to prohibit access to 
contaminated water. However, judicial enforcement of deed restrictions 
can be as effective as administrative enforcement of other 
institutional controls by a government agency. Therefore, deed 
restrictions are an acceptable institutional control if they are 
enforceable by a court with jurisdiction over the site at which they 
are used, and if the implementing agency will take appropriate steps to 
assure their effective application.
    Some commenters expressed the view that, if institutional controls 
are used, this use must be restricted to the 7-year period for 
remediation authorized in Section 112(a) of UMTRCA. EPA believes that 
it is not possible to achieve cleanup of groundwater at all of the 
sites within 7 years, no matter what reclamation scheme is employed. It 
is therefore necessary to consider time frames other than that 
originally contemplated in UMTRCA for completion of remedial actions. 
Congress, in granting an extension of the authorization in Section 
112(a) of UMTRCA for disposal and cleanup actions from March 5, 1990 to 
September 30, 1994, provided further ``* * * that the authority of the 
Secretary to perform groundwater restoration activities under this 
title is without limitation.'' (Uranium Mill Tailings Remedial Action 
Amendments Act of 1988 (42 U.S.C. 7916)). In addition, under Section 
104(f)(2) of the Act (42 U.S.C. 7919(f)(2)), the NRC may require 
maintenance of corrective and institutional measures that are already 
in place at the time authorization under Section 112(a) expires, 
without time limitation.
    The provisions for use of natural flushing when appropriate 
institutional controls are in place are consistent with existing 
regulations under Title II, although they are not explicit in those 
regulations. In cases where groundwater contamination is detected, the 
Title II regulations specify when corrective actions must begin, but do 
not specify a time when corrective actions must be completed. These 
provisions under Title I provide additional guidance on the length of 
time over which institutional control may reasonably be relied upon, 
and further guidance on the kinds of institutional provisions that 
would be appropriate at any uranium tailings site. In addition, use of 
institutional controls is not limited to extended remedial periods. 
Interim institutional controls may also be used to protect public 
health or the environment, when DOE finds them necessary and 
appropriate, prior to commencing active remedial action, during active 
remedial action, or during implementation of other compliance 
strategies.
    Other comments addressed a variety of matters, including the 
monitoring of institutional controls, the relationship between long-
term maintenance responsibilities and the 100-year limit on use of 
institutional controls, types of institutional controls, longer or 
shorter extended remedial periods, and the legality of institutional 
controls under UMTRCA. These matters are addressed in the Response to 
Comments, published separately as a background document.

Point of Compliance

    Several commenters objected to the definition of the point of 
compliance in the disposal standards (subpart A), and suggested that it 
be defined at some finite distance from the edge of the remediated 
tailings instead of at the downgradient edge of the pile, as in 
regulations established under RCRA. They indicated that the remediated 
tailings may seep a minor amount of contamination, which may cause the 
standards to be exceeded at the proposed point of compliance, under 
conditions where there would be no detriment to human health or the 
environment at small distances away. This difficulty can be solved, as 
proposed, by moving the point of compliance or, alternatively, by 
granting an ACL if it can be shown that such levels of contamination 
will not impair human health or damage the environment. We have 
concluded the latter is more in keeping with the regulations 
established under RCRA. The standards provide that DOE may request an 
ACL under such circumstances and NRC may approve such a request if 
contamination of groundwater will not endanger human health or degrade 
the environment. It is our view that this requirement would usually be 
satisfied at any site where the minor seepage noted above is not 
projected to extend beyond a few hundred meters from the waste 
management area and will not extend outside the site boundary. This 
could occur under a variety of circumstances where important roles are 
played by attenuation, dilution, or by vapor transport in unsaturated 
zones.
    Under the cleanup standard (subpart B), the DOE is required to 
characterize the extent of contamination from the site and clean it up 
wherever it exceeds the standards. This characterization and 
confirmation of cleanup will be carried out through the monitoring 
program established under Sec. 192.12(c)(3). Although the DOE is not 
required to clean up preexisting contamination that is located beneath 
a remediated tailings pile, they are required to consider this 
contamination when developing their plan(s) for remedial action and 
will have to clean up any contamination that will migrate from beneath 
the pile and exceed the concentration limits established in accordance 
with Sec. 192.02(c)(3).

Alternate Concentration Limits

    Several reviewers commented that EPA should not, for a variety of 
reasons, delegate the responsibility for approving ACLs to the NRC. 
Others stated that the standards were so strict that ACLs would be 
needed at every site. EPA considered a number of approaches to the 
provision for granting ACLs. These included deleting the ACL provision, 
establishing (by regulation) generic criteria for ACLs to be 
implemented by NRC, providing for some form of EPA review or oversight 
of ACL implementation, and (as in the proposed regulation) providing 
for no EPA role in setting ACLs at individual sites.
    EPA has decided not to delete the ACL provision because it is 
clearly needed, if for no other reason than to deal with the 
possibilities of unavoidable minor projected seepage over the extremely 
long-term design life (1000 years) of the disposal required, in most 
cases, by these standards, and of

[[Page 2858]]

cleanup situations involving pollutants for which no MCLs exist. 
Establishment of a complete set of regulations specifying generic 
criteria for granting ACLs presents difficulties for rulemaking, since 
ACL determinations often involve complex judgments that are not 
amenable to being reduced to simple regulatory requirements. In this 
regard we note that such regulations do not yet exist in final form for 
sites directly regulated under RCRA. However, the Agency has issued 
interim final Alternate Concentration Limit Guidance (OSWER Directive 
9481.00; EPA/SW-87-017), and has proposed several relevant rules, e.g., 
under 40 CFR parts 264, 265, 270, and 271, for Corrective Action for 
Solid Waste Management Units at Hazardous Waste Management Facilities 
(55 FR 30798; July 27, 1990). In addition, the NRC proposed a draft 
Technical Position on Alternate Concentration Limits for Uranium Mills 
at Title II sites on March 21, 1994 (59 FR 13345). EPA has reviewed the 
NRC draft Technical position, and we find that it is consistent, in 
general, with EPA's own guidance and proposed rules. The NRC draft 
position does not, however, specify an upper limit on risks to humans 
from carcinogens. We have reconsidered the issue of EPA review or 
oversight of ACLs at Title I sites in light of this review, and 
concluded that, in the interests of assuring that public health is 
adequately protected while at the same time minimizing the regulatory 
burden on DOE, the best course of action is to specify that upper limit 
in this regulation and assign the responsibility for making 
determinations for ACLs at individual sites to NRC. Accordingly, in 
this rule, in the implementing guidance contained in subpart C, 
Sec. 192.20(a)(2), we now specify that the criterion for known or 
suspected carcinogens contained in the above-referenced RCRA documents 
should be applied in granting ACLs. That criterion specifies that ACLs 
should be established at levels which represent an excess lifetime 
risk, at a point of exposure, no greater than 10-4 to 10-6 to 
an average individual.
    EPA is required by UMTRCA (Section 206) to be consistent, to the 
maximum extent practicable, with RCRA. For this reason, relevant 
portions of the RCRA regulations have been incorporated. For example, 
these regulations provide for the use of ACLs when it can be shown that 
the criteria specified in Sec. 192.02(c)(3)(ii) are satisfied. It 
remains the view of the Agency that, as at the Title II sites, an ACL 
is appropriate if the NRC has determined that these criteria are 
satisfied when the otherwise applicable standard will be met within the 
site boundary (or at a distance of 500 meters, if this is closer). It 
is clear that ACLs will usually be appropriate to accommodate the 
controlled minor seepage anticipated from properly designed tailings 
disposal within such distances, when public use is not possible.

Cost

    Greater consideration of cost and cost-benefit analysis was 
requested by several commenters. In 1983, Congress amended UMTRCA to 
provide that when establishing standards the Administrator should 
consider, among other factors, the economic costs of compliance. We 
have considered these costs in two ways. First, we compared them to the 
benefit, expressed in terms of the value of the product--processed 
uranium ore--which has led to contamination of groundwater at these 
sites. We estimate the present value of the processed uranium ore from 
these sites as approximately 3.9 billion dollars (1989 dollars). The 
estimated cost of compliance is approximately 5.5% of this value, and 
we judge this to be a not unreasonable incremental cost for the 
remediation of contamination from the operations which produced this 
uranium. As a second way of considering the economic costs of 
compliance, we examined the cost of alternative ways to supply the 
resources for future use represented by these groundwaters. As noted 
earlier, water is a scarce resource in the Western States where this 
cleanup would occur. When other resources have been exhausted, the only 
remaining alternative to cleaning up groundwater in the vicinity of 
these sites is to replace this water by transporting water from the 
nearest alternative source. Our analysis of the costs of doing this 
indicates that it is significantly more costly to supply water from 
alternative sources than it would be to clean up the groundwater at 
these sites. We have concluded, therefore, that this final rule 
involves a reasonable relationship between the overall costs and 
benefits of compliance.
    The RCRA subpart F regulations do not include cost as a 
consideration for the degree of cleanup of groundwater, and these 
regulations also do not provide for site-specific standards based on 
site-specific costs. Nonetheless, it is clearly desirable and 
appropriate to apply the most cost-effective remedies available to meet 
these standards at each site, and we anticipate that DOE will make such 
choices in choosing the remedies it applies to satisfy these standards. 
Further, once the basic criteria for establishing ACLs set forth in 
Sec. 192.02(c)(3)(ii)(B) have been satisfied, if a higher level of 
protection is reasonably achievable, this should be carried out. 
However, we do not believe it is appropriate to apply detailed cost/
benefit balancing judgments to justify lesser levels of protection for 
ground water. The benefits of cleaning up groundwater are often not 
quantifiable and may not become known for many years; therefore, site-
specific cost-benefit analyses are difficult to apply in such 
situations. Moreover, Congress provided no authority that protection of 
ground water at each site should be limited by cost/benefit 
considerations, even after reconsidering the question in the 1984 
amendments.
    Some reviewers raised the issue of additional costs arising from 
use of these standards in other applications, such as CERCLA cleanups. 
We recognize that there may be costs associated with using these 
standards as precedents for other waste cleanup projects. However, the 
reasonableness of incurring such costs should be assessed when it is 
possible to do so with complete information, that is, at the time of 
application of these standards as precedents for situations other than 
the one for which they were developed.

Natural Restoration

    The use of natural restoration of an aquifer was discussed by 
several reviewers. Some felt that it was a viable and desirable 
alternative, because it is easy and inexpensive to apply, for 
groundwaters that are not expected to be used for drinking or other 
purposes during the cleanup period. Others felt that it should be 
prohibited because it required a reliance on institutional controls and 
would circumvent active cleanup of groundwater. EPA believes that the 
use of natural restoration can be a viable alternative in situations 
where water use and ecological considerations are not affected, and 
cleanup will occur within a reasonable time. We have concluded that 
institutional controls, when enforced by government entities, or that 
otherwise have a high degree of permanence, can be relied on for 
periods of time up to 100 years, and that adequate safeguards are 
provided through NRC oversight of the implementation of these standards 
to prevent this alternative from being used to circumvent active 
cleanup of water that will be used by nearby populations.
    Commenters suggested that natural restoration was not adequate to 
restore water quality at these sites. DOE has indicated that they 
expect that natural restoration may be all that is necessary at up to 
eight sites and could be used

[[Page 2859]]

in conjunction with active remedial measures at several other sites. 
Natural restoration is most valuable when the contaminated aquifer 
discharges into a surface water body that will not be adversely 
affected by the contamination.

Pile and Liner Design

    The design of the remediated pile and the use of a liner was of 
concern to several commenters, and recommendations were given for 
suitable designs. These commenters feared that water would continually 
infiltrate the remediated piles and contaminate groundwater.
    These EPA standards would not be satisfied by designs which allow 
contamination that would adversely affect human health or the 
environment. Further, current engineering designs for covers 
incorporate a number of features that control infiltration to extremely 
low levels. These may include an erosion barrier (with vegetation, 
where feasible) to transpire moisture and reduce infiltration; rock 
filters and drains to drain and laterally disperse any episodic 
infiltration; very low permeability infiltration barriers to intercept 
residual infiltration; and finally, the thick radon barrier, which 
further inhibits infiltration. The combined effect of these features is 
to reduce the overall hydrological transmission of covers to levels on 
the order of one part in a billion, with a resulting high probability 
that there will be no saturated zone of leachate in or below the 
tailings. EPA expects DOE to use such state-of-the-art designs wherever 
it is appropriate to do so because of the proximity of groundwater.
    Under the provisions of UMTRCA, the detailed design of the pile and 
its cover is the responsibility of DOE, and confirmation of the 
viability of the design to satisfy EPA's standards is the 
responsibility of NRC. EPA's responsibility is to promulgate the 
standards to which the disposal must conform. It would be inconsistent 
with the division of responsibilities set forth in UMTRCA to specify 
actual designs for the piles in these regulations. In this connection, 
the requirement to provide a liner when tailings are moved to a new 
location in a wet state is properly seen as a generic management 
requirement. Any liner for this purpose would only serve a useful 
purpose for the relatively short time over which the moisture content 
of the pile adjusts to its long-term equilibrium value, after which the 
cover design would determine the groundwater protection capability of 
the disposal.

Restricted List of Constituents

    Commenters were overwhelmingly opposed to a restricted list of 
radioactive or toxic constituents and recommended that the entire list 
of constituents be relied upon. It is the Agency's experience that, 
under RCRA, no changes in this list have been requested based on the 
criteria provided in Sec. 264.93(b). These criteria allow for hazardous 
constituents to be excluded based on a determination that the 
constituent does not pose a substantial present or potential hazard to 
human health or the environment. Therefore, that portion of the RCRA 
standards which specify conditions for the exclusion of constituents 
from the RCRA list of hazardous constituents has been excluded as 
unnecessary.
    However, a short list of compounds has been developed by EPA for 
use in monitoring groundwater under RCRA. This rule incorporates that 
list of constituents (Appendix IX of part 264) in place of the complete 
list in Appendix I for the monitoring programs required at 
Secs. 192.02(c)(1), 192.03, and 192.12(c)(1). However, the rule still 
requires that all hazardous constituents listed in Appendix I be 
considered when corrective action is necessary.

IV. Summary of the Final Standard

    These final standards consist of three parts: a first part 
governing protection against future groundwater contamination from 
tailings piles after disposal; a second part that applies to the 
cleanup of contamination that occurred before disposal of the tailings 
piles; and a third part that provides guidance on implementation and 
specifies conditions under which supplemental standards may be applied.

A. The Groundwater Standard for Disposal

    The standard for protection of groundwater after disposal (subpart 
A) is divided into two parts that separately address actions to be 
carried out during periods of time designated as the disposal and post-
disposal periods. The disposal and post-disposal periods are defined in 
a manner analogous to the closure and post-closure periods, 
respectively, in RCRA regulations. However, there are some differences 
regarding their duration and the timing of any corrective actions that 
may become necessary due to failure of disposal systems to perform as 
designed. (Because there are no mineral processing activities currently 
at these inactive sites, standards are not needed for an operational 
period.) The disposal period, for the purpose of this regulation, is 
defined as that period of time beginning on the effective date of the 
original Title I part 192 standard for the inactive sites (March 7, 
1983) and ending with completion of all actions related to disposal 
except post-disposal monitoring and any corrective actions that might 
become needed as a result of failure of completed disposal. The post-
disposal period begins with completion of disposal actions and ends 
after an appropriate period for the monitoring of groundwater to 
confirm the adequacy of the disposal. The groundwater standard 
governing the actions to be carried out during the disposal period 
incorporates relevant requirements from subpart F of part 264 of this 
chapter (Secs. 264.92-264.95). The standard for the post-disposal 
period reflects relevant requirements of Sec. 264.111 of this Chapter. 
The disposal standard also includes provisions for monitoring and any 
necessary corrective action during both disposal and post-disposal 
periods. These provisions are essentially the same as those governing 
the licensed (Title II) uranium mill tailings sites (40 CFR 192, 
subparts D and E; see also the Federal Register notices for those 
standards published on April 29, 1983 and on October 7, 1983). Several 
additional constituents are regulated, however, in these final Title I 
regulations.
    These regulations do not change existing requirements at Title I 
sites for the period of time disposal must be designed to comply with 
the standards, and therefore remain identical to the requirements for 
licensed (Title II) sites in this respect. The Agency also recently 
promulgated final regulations for spent nuclear fuel, and high level 
and transuranic radioactive wastes (40 CFR part 191; 58 FR 66398, 
December 20, 1993). Those standards specify a different design period 
for compliance (10,000 years versus 1000 years) for two principle 
reasons: (1) The level of radioactivity, and therefore the level of 
health risk, in the wastes addressed under 40 CFR part 191 is many 
orders of magnitude greater than those addressed here. (The 
radioactivity of tailings is typically 0.4 to 1.0 nCi/g, 40 CFR part 
191 wastes are always greater than 100 nCi/g, and are typically far 
higher.) (2) The volume of uranium mill tailings is far greater than 
the waste volumes addressed under 40 CFR part 191. The containment that 
would be required to meet a 10,000 year requirement is simply not 
feasible for the volumes of tailings involved (the option of 
underground disposal was addressed and rejected in the original

[[Page 2860]]

rulemakings for the Title I and Title II sites).
    These regulations require installation of monitoring systems 
upgradient of the point of compliance (i.e., in the uppermost aquifer 
upgradient of the edge of the tailings disposal site) or at some other 
point adequate to determine background levels of any listed 
constituents that occur naturally at the site. The disposal should be 
designed to control, to the extent reasonably achievable for 1000 years 
and, in any case, for at least 200 years, all listed constituents 
identified in residual radioactive materials at the site to levels for 
each constituent derived in accordance with Sec. 192.02(c)(3). 
Accordingly, the elements of the groundwater protection standard to be 
specified for each disposal site include a list of relevant 
constituents, the concentration limits for each such constituent, and 
the compliance point.
    These standards provide for consideration of ACLs if the disposal 
cannot reasonably be designed to assure conformance to background 
levels (or those in Table 1) over the required term. ACLs can be 
granted provided that, after considering practicable corrective 
actions, a determination can be made that it satisfies the values given 
by implementing the conditions for ACLs under Sec. 192.02(c)(3)(ii).
    The standards for Title II sites require use of a liner under new 
tailings piles or lateral extensions of existing piles. These standards 
for remedial action at the inactive Title I sites do not contain a 
similar provision. EPA assumes that the inactive piles will not need to 
be enlarged. Several, however, will be relocated. However, unlike 
tailings at the Title II sites, which generally may contain large 
amounts of process water, the inactive tailings contain little or no 
free water. Such tailings, if properly located and stabilized with a 
cover adequate to ensure an unsaturated zone, are not likely to require 
a liner in order to protect groundwater.
    However, a liner would be needed for an initial drying-out period 
to meet these groundwater standards if a situation arose where the 
tailings initially contained water above the level of specific 
retention. For example, tailings to which water was added to facilitate 
their removal to a new site (i.e., through slurrying), or for 
compaction during disposal. (It is anticipated that piles will never be 
moved to areas of high precipitation or situated within a zone of water 
table fluctuation.) Section 192.20(a)(3) requires the remedial plan to 
address how any such excess water in tailings would be dealt with. In 
such circumstances it will normally be necessary to use a liner or 
equivalent to assure that groundwater will not be contaminated while 
the moisture level in the tailings adjusts to its long-term equilibrium 
value. Currently, however, DOE plans do not include slurrying any 
tailings to move them to new locations. Further, for all but two sites, 
of which one has already been closed (Canonsburg) and at the other 
(Falls City) disposal actions are well advanced, the tailings are 
located in arid areas where annual precipitation is low.
    Disposal designs which prevent migration of listed constituents in 
the groundwater for only a short period of time would not provide 
appropriate protection. Such approaches simply defer adverse 
groundwater effects. Therefore, measures which only modify the gradient 
in an aquifer or create barriers (e.g., slurry walls) would not of 
themselves provide an adequate disposal.
    Section 192.02(d) requires that a site be closed in a manner that 
minimizes further maintenance. Depending on the physical properties of 
the sites, candidate disposal systems, and the effects of natural 
processes over time, measures required to satisfy these standards will 
vary from site to site. Actual site data, computational models, and 
prevalent expert judgment may be used in deciding that proposed 
measures will satisfy the standards. Under the provisions of Section 
108(a) of UMTRCA, the adequacy of these judgments is determined by the 
NRC.
    For the post-disposal period, a groundwater monitoring plan is 
required to be developed and implemented. The plan will require 
monitoring for a period of time deemed sufficient to verify, with 
reasonable assurance, the adequacy of the disposal to achieve its 
design objectives for containment of listed constituents. EPA expects 
this period of time to be comparable, in most cases, to that required 
under Sec. 264.117 of Title 40 for waste sites regulated under RCRA 
(i.e., a few decades). However, there may be situations where longer or 
shorter periods are appropriate. Installation and commencement of the 
monitoring required under Sec. 192.03 will satisfy this EPA standard, 
for the purposes of licensing of the site by the NRC.
    With regard to this monitoring, UMTRCA provides that, after 
remediation is completed and custody is transferred to a Federal 
agency, NRC may require that the Federal agency having custody of each 
remediated tailings site ``* * * undertake such monitoring, 
maintenance, and emergency measures * * *and other actions as [NRC] 
deems necessary to comply with [EPA's standards]'' (UMTRCA, Section 
104(f)(2)). Although it is not intended that routine monitoring be 
carried out as a requirement for conformance to these standards for the 
200- to 1000-year period over which the disposal is designed to be 
effective, NRC may require more extensive monitoring to comply with 
EPA's standards, as NRC deems necessary under Sec. 104(f)(2) of the 
Act.
    During the post-disposal period, if listed constituents from a 
disposal site are detected in excess of the groundwater standards, 
these regulations require a corrective action program designed to bring 
the disposal and the groundwater into compliance with the provisions of 
Sec. 192.02(c)(3) and subpart B, respectively. In designing such a 
corrective action program, the implementing agencies may consider all 
of the provisions available under subparts A, B, and C. A modification 
of the monitoring program sufficient to demonstrate that the corrective 
measures will be successful is also required. In designing future 
corrective action programs, the implementing agencies may also wish to 
consider the guidance provided by new regulations now being developed 
for the RCRA program that will be proposed as subpart S to Title 40. 
However, the requirements of Part 192 will still govern regulatory 
determinations of acceptability.
Additional Regulated Constituents
    For the purpose of this regulation only, the Agency is regulating, 
in addition to the hazardous constituents referenced by Sec. 264.93, 
molybdenum, nitrate, combined radium-226 and radium-228, and combined 
uranium-234 and uranium-238. Molybdenum, radium, and uranium were 
addressed by the Title II standards because these radioactive and/or 
toxic constituents are found in high concentrations at many mill 
tailings sites. These regulations add numerical limits for these 
constituents. Nitrate was added because it had been identified in 
concentrations far in excess of drinking water standards in groundwater 
at a number of the inactive sites.
    The concentration limit for molybdenum in groundwater from uranium 
tailings is set at 0.1 milligram per liter. This is the value of the 
provisional Adjusted Acceptable Daily Intake (AADI) for drinking water 
developed by EPA under the Safe Drinking Water Act (50 FR 46958). The 
Agency has established neither a maximum concentration limit goal

[[Page 2861]]

(MCLG) nor a maximum concentration limit (MCL) for molybdenum because 
it occurs only infrequently in water. According to the most recent 
relevant report of the National Academy of Sciences (Drinking Water and 
Health, 1980, Vol. III), molybdenum from drinking water, except for 
highly contaminated sources, is not likely to constitute a significant 
portion of the total human intake of this element. However, as noted 
above, uranium tailings are often a highly concentrated source of 
molybdenum, and it is therefore appropriate to include a standard for 
molybdenum in this rule. In addition to the hazard to humans, our 
analysis of toxic substances in tailings in the Final Environmental 
Impact Statement for Remedial Action Standards for Inactive Uranium 
Processing Sites (EPA 520/4-82-013-1) found that, for ruminants, 
molybdenum in concentrations greater than 0.05 ppm in drinking water 
would lead to chronic toxicity. This concentration included a safety 
factor of 10; the standard provides for a safety factor of 5, which we 
consider adequately protective for ruminants.
    The standard for combined uranium-234 and uranium-238 due to 
contamination from uranium tailings is 30 pCi per liter. The level of 
health risk associated with this standard is equivalent to the level 
proposed as the MCL for uranium in drinking water by EPA (56 FR 33050, 
July 18, 1991). The standard promulgated here applies to remedial 
actions for uranium tailings only. When the Agency has established a 
final MCL for isotopes of uranium in drinking water, we will consider 
whether this standard needs to be reviewed.
    The limit for nitrate (as nitrogen) is 10 mg per liter. This is the 
value of the drinking water standard for nitrate.

B. The Cleanup Standard

    With the exception of the point of compliance provision, the 
standard (subpart B) for cleanup of contaminated groundwater contains 
the same basic provisions as the standard for disposal in subpart A. In 
addition, it provides for the establishment of supplemental standards 
under certain conditions, and for use of institutional control to 
permit passive restoration through natural flushing when no public 
water system is involved.
    Although the standards specify a single point of compliance for 
conformance to the groundwater standards for disposal, this does not 
suffice for the cleanup of groundwater that has been contaminated 
before final disposal. Instead, in this case compliance must be 
achieved anywhere contamination above the levels established by these 
standards is found or is projected to be found in groundwater outside 
the disposal area and its cover. The standards require DOE to establish 
a monitoring program adequate to determine the extent of contamination 
(Sec. 192.12(c)(1)) in groundwater around each processing site. The 
possible presence of any of the inorganic or organic hazardous 
constituents identified in tailings or used in the processing operation 
should be assessed. The plan for remedial action referenced under 
Sec. 192.20(b)(4) should document the extent of contamination, the rate 
and direction of movement of contaminants, and consider future movement 
of the plume. The cleanup standards normally require restoration of all 
contaminated groundwater to the levels provided for under 
Sec. 192.02(c)(3). These levels are either background concentrations, 
the levels specified in Table 1 in the rule, or ACLs. In cases where 
the groundwater is not classified as of limited use, any ACL should be 
determined under the assumption that the groundwater may be used for 
drinking purposes. In certain circumstances, however, supplemental 
standards set at levels that would be achieved by remedial actions that 
come as close to meeting the otherwise applicable standards as is 
reasonably achievable under the circumstances may be appropriate. Such 
supplemental standards and ACLs are distinct regulatory provisions and 
may be considered independently. The regulations provide that 
supplemental standards may be granted if:
     Groundwater at the site is of limited use (Sec. 192.11(e)) 
in the absence of contamination from residual radioactive materials; or
     Complete restoration would cause more environmental harm 
than it would prevent; or
     Complete restoration is technically impracticable from an 
engineering perspective.
    The use of supplemental standards for limited use groundwater 
applies the groundwater classification system proposed in EPA's 1984 
Groundwater Protection Strategy. As proposed for use in these standards 
(52 FR 36003, September 24, 1987), Class III encompasses groundwaters 
that are not a current or potential source of drinking water because of 
widespread, ambient contamination caused by natural or human-induced 
conditions, or cannot provide enough water to meet the needs of an 
average household. These standards adopt the proposed definition of 
limited use groundwater. However, for the purpose of qualifying for 
supplemental standards, human-induced conditions exclude contributions 
from residual radioactive materials.
    Water which meets the definition of limited use groundwater may, 
nevertheless, reasonably be or be projected to be useful for domestic, 
agricultural, or industrial purposes. For example, in some locations 
higher quality water may be scarce or absent. Therefore, Sec. 192.22(d) 
requires the implementing agencies to remove any additional 
contamination that has been contributed by residual radioactive 
materials to the extent that is necessary to preserve existing or 
reasonably projected beneficial uses in areas of limited water 
supplies. At a minimum, at sites with limited use groundwater, the 
supplemental standards require such management of contamination due to 
tailings as is required to assure protection of human health and the 
environment from that contamination. For example, if the additional 
contamination from the tailings would cause an adverse effect on 
drinkable groundwater that has a significant interconnection with 
limited use groundwater over which the tailings reside, then the 
additional contamination from the tailings will have to be abated.
    Supplemental standards are also appropriate in certain other cases 
similar to those addressed in Section 121(d)(4) of the Superfund 
Amendments and Reauthorization Act of 1986 (SARA). SARA recognizes that 
cleanup of contamination could sometimes cause environmental harm 
disproportionate to the effects it would alleviate. For example, if 
fragile ecosystems would be impaired by any reasonable restoration 
process (or by carrying a restoration process to extreme lengths to 
remove small amounts of residual contamination), then it might be 
prudent not to completely restore groundwater quality. Such a situation 
might occur, for example, if the quantity of water that would be lost 
during remediation is a significant fraction of that available in an 
aquifer that recharges very slowly. Decisions regarding tradeoffs of 
environmental damage can only be based on characteristics peculiar to 
the specific location of the site. We do not yet know whether such 
situations exist in the UMTRCA program, but EPA believes that use of 
supplemental standards should be possible in such situations, after 
thorough investigation and consideration of all reasonable restoration 
alternatives.

[[Page 2862]]

    Based on currently available information, we are not aware that at 
least substantial restoration of groundwater quality is technically 
impracticable from an engineering perspective at any of the designated 
sites. However, our information is incomplete. For example, there may 
not be enough water available in a very small aquifer to carry out 
remediation and retain the groundwater resource, or, in other cases, 
some contaminants may not be removable without destroying the aquifer. 
EPA believes that DOE should not be required to institute active 
measures that would completely restore groundwater at these sites if 
such restoration is technically impracticable from an engineering 
perspective, and if, at a minimum, protection of human health and the 
environment is assured. Consistent with the provisions of SARA for 
remediation of waste sites generally, the standards therefore permit 
supplemental standards in such situations at levels achievable by site-
specific alternate remedial actions. A finding of technical 
impracticability from an engineering perspective requires careful and 
extensive documentation, including an analysis of the degree to which 
remediation is practicable. It should be noted that the phrase 
``technically impracticable from an engineering perspective'' means 
that the remedial action cannot reasonably be put into practice; it 
does not mean a conclusion derived from the balancing of costs and 
benefits. In addition to documentation of technical matters related to 
cleanup technology, DOE should also include a detailed assessment of 
such site-specific matters as transmissivity of the geologic formation, 
aquifer recharge and storage, contaminant properties (e.g., withdrawal 
and treatability potential), and the extent of contamination.
    Finally, for aquifers where compliance with the groundwater 
standards can be projected to occur naturally within a period of less 
than 100 years, and where the groundwater is not now used for a public 
water system and is not now projected to be so used within this period, 
this rule permits extension of the remedial period to that time, 
provided institutional control and an adequate verification plan which 
assures satisfaction of beneficial uses is established and maintained 
throughout this extended remedial period.
    Active restoration should be carefully considered when evaluating 
the use of such passive restoration. The provision to permit reliance 
on natural restoration is based on the judgment that sole reliance on 
active cleanup may not always be warranted under these standards 
promulgated pursuant to UMTRCA. This may be the case for situations 
where active cleansing to completely achieve the standards is 
impracticable, environmentally damaging, or excessively costly, if 
groundwater can reach the levels required by the standards through 
natural flushing within an acceptable period of time. This mechanism 
may be considered where groundwater concentration limits can be met 
through partial (or complete) reliance on natural processes and no use 
of the water as a source for a public water system exists or is 
projected. Any institutional control that may be required to 
effectively protect public health and the environment and assure that 
beneficial uses that the water could have satisfied are provided for in 
the interim must be verified for effectiveness and modified as 
necessary. Alternate standards are not required where final cleanup is 
to be accomplished through natural flushing, since those established 
under Sec. 192.02(c)(3) must be met at the end of the remedial period.
    The regulations establish a time limit on such extension of the 
remedial period to limit reliance on extended use of institutional 
controls to manage public access to contaminated groundwater. Following 
the precedent established by our rule for high-level radioactive wastes 
(40 CFR 191.14(a)), use of institutional controls is permitted for this 
purpose only when they will be needed for periods of less than 100 
years.
    The effectiveness of institutional controls must be verified and 
maintained over the entire period of time that they are in use. 
Examples of acceptable measures include use restrictions enforceable by 
the administrative or judicial branches of government entities, and 
measures with a high degree of permanence, such as Federal or State 
ownership of the land containing the contaminated water. In some 
instances, a combination of institutional controls may be needed to 
provide adequate protection, such as providing an alternate source of 
water for drinking or other beneficial uses and restricting 
inappropriate use of contaminated groundwater. However, institutional 
control provisions are not intended to require DOE to provide water for 
uses that the groundwater would not have been available or suitable for 
in the absence of contamination from residual radioactive materials. 
Institutional controls that are not adequate by themselves include such 
measures as health advisories, signs, posts, admonitions, or any other 
measure that requires the voluntary cooperation of private parties. 
However, such measures may be used to complement other enforceable 
institutional controls.
    Restoration of groundwater may be carried out by removal, wherein 
the contaminated water is removed from the aquifer, treated, and either 
disposed of, used, or re-injected into the aquifer, and in situ, 
through the addition of chemical or biological agents to fix, reduce, 
or eliminate the contamination in place. Appropriate restoration will 
depend on characteristics of specific sites and may involve use of a 
combination of methods. Water can be removed from an aquifer by pumping 
it out through wells or by collecting the water from intercept 
trenches. Slurry walls can sometimes be put in place to contain 
contamination and prevent further migration of contaminants, so that 
the volume of contaminated water that must be treated is reduced. The 
background information document contains a more extensive discussion of 
candidate restoration methods.
    Previously EPA reviewed preliminary information for all 24 sites 
and detailed information for 14 to make a preliminary assessment of the 
extent of the potential applicability of supplemental standards and the 
use of passive remediation. Approximately two-thirds of the sites 
appear to be located over potable (or otherwise useful) groundwater and 
the balance over limited use groundwaters. DOE, based on more recent 
information, feels that up to ten sites are candidates for supplemental 
standards, and that the rate at which natural flushing is occurring at 
up to eight of the sites permits consideration of passive remediation 
under institutional control as the sole remedial method. Some sites 
exhibit conditions that could be amenable to a combination of 
strategies. Further, EPA is not able to predict the applicability of 
provisions regarding technical impracticability or excess environmental 
harm, since this requires detailed analysis of specific sites, but 
anticipates that wide application is unlikely. It is emphasized that 
the above assessment is not based on final results for the vast 
majority of these sites, and is, therefore, subject to change.
    RCRA regulations, for hazardous waste disposal units regulated by 
EPA, provide that acceptable concentrations of constituents in 
groundwater (including ACLs) are determined by the Regional 
Administrator (or an authorized State). EPA's regulations under Title 
II of UMTRCA provide that the NRC, which regulates active sites, 
replace the EPA Regional Administrator for the above functions when any

[[Page 2863]]

contamination permitted by an ACL will remain on the licensed site or 
within 500 meters of the disposal area, whichever is closer. Because 
Section 108(a) of UMTRCA requires the Commission's concurrence with 
DOE's selection and performance of remedial actions to conform to EPA's 
standards, this rule makes the same provision for administration by the 
NRC of those functions for Title I as it did in the case of the Title 
II standards, and also provides for NRC concurrence on supplemental 
standards.

V. Implementation

    UMTRCA requires the Secretary of Energy to select and perform the 
remedial actions needed to implement these standards, with the full 
participation of any State that shares the cost. The NRC must concur 
with these actions and, when appropriate, the Secretary of Energy must 
also consult with affected Indian tribes and the Secretary of the 
Interior.
    The cost of remedial actions is being borne by the Federal 
Government and the States as prescribed by UMTRCA. The clean-up of 
groundwater is a large-scale undertaking for which there is relatively 
little long-term experience. Groundwater conditions at the inactive 
processing sites vary greatly, and, as noted above, engineering 
experience with some of the required remedial actions is limited. 
Although preliminary engineering assessments have been performed, 
specific engineering requirements and detailed costs to meet the 
groundwater standards at each site have yet to be determined. We 
believe that costs averaging about 10-15 million (1993) dollars for 
each of the approximately fourteen tailings sites at which remedial 
action may be required are most likely.
    The benefits from the cleanup of this groundwater are difficult to 
quantify. In some instances, groundwater that is contaminated by 
tailings is now in use and will be restored. Future uses that will be 
preserved by cleanup are difficult to project. In the areas where the 
tailings were processed, groundwater is an important resource due to 
the arid condition of the land. However, much of the contamination at 
these sites occurs in shallow alluvial aquifers. At some of these sites 
such aquifers have limited use because of their generally poor quality 
and the availability of better quality water from deeper aquifers.
    Implementation of the disposal standard for protection of 
groundwater will require a judgment that the method chosen provides a 
reasonable expectation that the provisions of the standard will be met, 
to the extent reasonably achievable, for up to 1000 years and, in any 
case, for at least 200 years. This judgment will necessarily be based 
on site-specific analyses of the properties of the sites, candidate 
disposal systems, and the potential effects of natural processes over 
time. Therefore, the measures required to satisfy the standard will 
vary from site to site. Actual site data, computational models, and 
expert judgment will be the major tools in deciding that a proposed 
disposal system will satisfy the standard.
    The purpose of the groundwater cleanup standard is to provide the 
maximum reasonable protection of public health and the environment. 
Costs incurred by remedial actions should be directed toward this 
purpose. We intend the standards to be implemented using verification 
procedures whose cost and technical requirements are reasonable. 
Procedures that provide a reasonable assurance of compliance with the 
standards will be adequate. Measurements to assess existing 
contamination and to determine compliance with the cleanup standards 
should be performed with 1 reasonable survey and sampling procedures 
designed to minimize the cost of verification.
    The explanations regarding implementation of these regulations in 
Secs. 192.20(a)(2) and (3) have been revised to remove those provisions 
that the Court remanded and to reflect these new requirements.
    These standards are not expected to affect the disposal work DOE 
has already performed on tailings. On the basis of consultations with 
DOE and NRC, we expect, in general, that a pile designed to comply with 
the disposal standards proposed on September 24, 1987, will also comply 
with these disposal standards for the control of groundwater 
contamination. DOE will have to determine, with the concurrence of the 
NRC, what additional work may be needed to comply with the groundwater 
cleanup requirements. However, any such cleanup work should not 
adversely affect the control systems for tailings piles that have 
already been or are currently being installed.
    However, at three sites (Canonsburg, PA; Shiprock, NM; and Salt 
Lake City, UT) the disposal design was based on standards remanded in 
part on September 3, 1985. We have considered these sites separately, 
based on information supplied by DOE, and reached the tentative 
conclusion that modification of the existing disposal cells is not 
warranted at any of them. Final determinations will be made by DOE, 
with the concurrence of NRC.
    The disposal site at Canonsburg, PA, is located above the banks of 
Chartiers Creek. Contamination that might seep from the encapsulated 
tailings will reach the surface within the site boundary, and is then 
diluted by water in the creek to insignificant levels. Under these 
circumstances, this site qualifies for an ACL under 
Sec. 192.02(c)(3)(ii), and modification of the existing disposal cell 
is not warranted.
    The site at Shiprock, NM, which is located above the floodplain of 
the San Juan River, is over an aquifer that may not be useful as a 
source of water for drinking or other beneficial purpose because of its 
quality, areal extent, and yield. Most of the groundwater in this 
aquifer appears to have originated from seepage of tailings liquor from 
mill impoundments and not to be contributing to contamination of any 
currently or potentially useful aquifer. Additionally, the quality of 
this water may be degraded by uncontrolled disposal of municipal refuse 
north and south of the site. DOE is currently in the process of 
completing its characterization of this groundwater, and may or may not 
recommend use of a supplemental standard under Sec. 192.21(g). In any 
case, however, it appears unlikely that modification of the existing 
disposal cell will be necessary.
    The site containing the tailings from the Salt Lake City mill is 
located at Clive, Utah, over groundwater that contains dissolved solids 
in excess of 10,000 mg/l and is not contributing to contamination of 
any currently or potentially useful aquifer. Under these circumstances, 
this site also qualifies for a supplemental standard under 
Sec. 192.21(g), and modification of the existing disposal cell is not 
warranted.

VI. Relationship to Other Policy and Requirements

    In July 1991 EPA completed development of a strategy to guide 
future EPA and State activities in groundwater protection and cleanup. 
A key element of this strategy is a statement of `EPA Groundwater 
Protection Principles' \1\ that has as its overall goals the prevention 
of adverse effects on human health and the environment and protection 
of the environmental integrity of the nation's groundwater resources. 
To achieve these

[[Page 2864]]

goals, EPA developed principles regarding prevention; remediation; and 
Federal, State, and local responsibilities. These principles are set 
forth and their implementation by this rule summarized below.
---------------------------------------------------------------------------

    \1\ Protecting the Nation's Groundwater: EPA's Strategy for the 
1990s, The Final Report of the EPA Groundwater Task Force, U.S. 
Environmental Protection Agency, Washington, (Report 21Z-1020), July 
1991.

    (1) With respect to prevention: groundwater should be protected 
to ensure that the nation's currently used and reasonably expected 
drinking water supplies, both public and private, do not present 
adverse health risks and are preserved for present and future 
generations. Groundwater should also be protected to ensure that 
groundwater that is closely hydrologically connected to surface 
waters does not interfere with the attainment of surface water 
quality standards, which is necessary to protect the integrity of 
associated ecosystems. Groundwater protection can be achieved 
through a variety of means including: pollution prevention programs; 
source controls; siting controls; the designation of wellhead 
protection areas and future public water supply areas; and the 
protection of aquifer recharge areas. Efforts to protect groundwater 
must also consider the use, value, and vulnerability of the 
---------------------------------------------------------------------------
resource, as well as social and economic values.

    This rule for uranium mill tailings protects groundwater by 
requiring that disposal piles be designed to avoid any new 
contamination of groundwater that would threaten human health or the 
environment in the future. Water is scarce in the Western States where 
these disposal sites occur. Currently almost half of the water consumed 
in Arizona and New Mexico and 20 to 30 percent of the water consumed in 
Utah, Colorado, Idaho, and Texas is groundwater. The population in the 
Mountain States is expected to increase more than that of any other 
region between now and the year 2010. In particular, the population in 
Colorado, New Mexico, Arizona, and Utah is expected to increase 
dramatically. Thus, in order to ensure that all currently used and 
reasonably expected drinking water supplies near these sites, both 
public and private, are adequately protected for use by present and 
future generations, these rules apply drinking water standards to all 
potable groundwater. The rule also requires that hydrologically-
connected aquifers and surface waters, including designated wellhead 
protection areas and future public water supply areas, be identified 
and protected, and that other beneficial uses of groundwater besides 
drinking be identified and protected, including the integrity of 
associated ecosystems. In this regard we note that DOE has not 
identified any critical aquatic habitats that have been or could be 
adversely affected by contamination from these sites.

    (2) With respect to remediation: groundwater remediation 
activities must be prioritized to limit the risk of adverse effects 
to human health risks first and then to restore currently used and 
reasonably expected sources of drinking water and groundwater 
closely hydrologically connected to surface waters, whenever such 
restorations are practicable and attainable.

    Pursuant to our responsibilities under Section 102(b) of UMTRCA, 
EPA advised DOE in 1979 concerning the criteria which should govern the 
order in which these sites should be cleaned up. Those criteria 
specified, in essence, that sites capable of affecting the health of 
human populations the most should be remediated first. As a result DOE 
has divided the 24 sites into three levels of priority, based on the 
populations affected. In order to facilitate implementation of these 
principles, we have, in this rule, provided DOE with flexibility to 
prioritize their cleanup activities so as to first minimize human 
exposure, then restore reasonably expected drinking water sources, and 
finally to clean up groundwater only when restoration is practicable 
and attainable. This has been done by relaxing the requirements for 
cleanup of water:
    (a) If it is not a current or potential source of drinking water 
(i.e., it meets the definition of limited use),
    (b) Where natural processes will achieve the standards and there is 
no current or planned use,
    (c) Where adverse environmental impact will occur, and (d) where 
cleanup is technologically impracticable.

    (3) With respect to Federal, State, and local responsibilities: 
the primary responsibility for coordinating and implementing 
groundwater protection programs has always been and should continue 
to be vested with the States. An effective groundwater protection 
program should link Federal, State, and local activities into a 
coherent and coordinated plan of action. EPA should continue to 
improve coordination of groundwater protection efforts within the 
Agency and with other Federal agencies with groundwater 
responsibilities.

    In the case of the sites covered by these regulations, UMTRCA 
specifies a primary role for Federal rather than State agencies. 
However, since these regulations are modeled after existing RCRA 
regulations, this will serve to insure coherence and coordination with 
similar prevention and remediation actions by EPA, the States, and 
other Federal agencies. For example, the concentration limits in 
groundwater for listed constituents at the sites covered by this rule 
are the same as those specified for cleanup and disposal at RCRA sites 
by EPA and the States and at uranium mill sites licensed by NRC.

Executive Order 12866

    Under Executive Order 12866 (58 FR 51735; October 4, 1993), EPA 
must determine whether a rule is ``significant'' and therefore subject 
to review by the Office of Management and Budget (OMB) and the 
requirements of the Executive Order. The Order defines ``significant 
regulatory action'' as one that is likely to result in a rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely effect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local or tribal governments or communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of the 
recipients thereof; or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    Pursuant to the terms of Executive Order 12866, it has been 
determined that this rule is may be a ``significant regulatory 
action,'' because it may qualify under criterion #4 above on the basis 
of comments submitted to EPA by letter on January 15, 1993, as a result 
of OMB review under the previous Executive Order 12291. This action was 
therefore resubmitted to OMB for review. Comments from OMB to EPA for 
their review under the previous Executive Order and EPA's response to 
those comments are included in the docket. Any changes made in response 
to OMB suggestions or recommendations as a result of the current review 
will be documented in the public record.

Paperwork Reduction Act

    Under the Paperwork Reduction Act of 1986, the Agency is required 
to state the information collection requirements of any standard 
published on or after July 1, 1988. In response to this requirement, 
this standard contains no information collection requirements and 
imposes no reporting burden on the public.

List of Subjects in 40 CFR Part 192

    Environmental protection, Groundwater, Radiation protection, 
Uranium.


[[Page 2865]]


    Dated: December 14, 1994.
Carol M. Browner,
Administrator, Environmental Protection Agency.
    For the reasons set forth in the preamble, 40 CFR part 192 is 
amended as follows:

PART 192--HEALTH AND ENVIRONMENTAL PROTECTION STANDARDS FOR URANIUM 
AND THORIUM MILL TAILINGS

    1. The authority citation for part 192 continues to read as 
follows:

    Authority: Section 275 of the Atomic Energy Act of 1954, 42 
U.S.C. 2022, as added by the Uranium Mill Tailings Radiation Control 
Act of 1978, Pub. L. 95-604, as amended.

Subpart A--Standards for the Control of Residual Radioactive 
Materials From Inactive Uranium Processing Sites

    2. Section 192.01 is amended by revising paragraphs (a) and (e) and 
adding paragraphs (g) through (r) to read as follows:


Sec. 192.01  Definitions.

    (a) Residual radioactive material means:
    (1) Waste (which the Secretary determines to be radioactive) in the 
form of tailings resulting from the processing of ores for the 
extraction of uranium and other valuable constituents of the ores; and
    (2) Other wastes (which the Secretary determines to be radioactive) 
at a processing site which relate to such processing, including any 
residual stock of unprocessed ores or low-grade materials.
* * * * *
    (e) Depository site means a site (other than a processing site) 
selected under Section 104(b) or 105(b) of the Act.
* * * * *
    (g) Act means the Uranium Mill Tailings Radiation Control Act of 
1978, as amended.
    (h) Administrator means the Administrator of the Environmental 
Protection Agency.
    (i) Secretary means the Secretary of Energy.
    (j) Commission means the Nuclear Regulatory Commission.
    (k) Indian tribe means any tribe, band, clan, group, pueblo, or 
community of Indians recognized as eligible for services provided by 
the Secretary of the Interior to Indians.
    (l) Processing site means:
    (1) Any site, including the mill, designated by the Secretary under 
Section 102(a)(1) of the Act; and
    (2) Any other real property or improvement thereon which is in the 
vicinity of such site, and is determined by the Secretary, in 
consultation with the Commission, to be contaminated with residual 
radioactive materials derived from such site.
    (m) Tailings means the remaining portion of a metal-bearing ore 
after some or all of such metal, such as uranium, has been extracted.
    (n) Disposal period means the period of time beginning March 7, 
1983 and ending with the completion of all subpart A requirements 
specified under a plan for remedial action except those specified in 
Sec. 192.03 and Sec. 192.04.
    (o) Plan for remedial action means a written plan (or plans) for 
disposal and cleanup of residual radioactive materials associated with 
a processing site that incorporates the results of site 
characterization studies, environmental assessments or impact 
statements, and engineering assessments so as to satisfy the 
requirements of subparts A and B of this part. The plan(s) shall be 
developed in accordance with the provisions of Section 108(a) of the 
Act with the concurrence of the Commission and in consultation, as 
appropriate, with the Indian Tribe and the Secretary of Interior.
    (p) Post-disposal period means the period of time beginning 
immediately after the disposal period and ending at termination of the 
monitoring period established under Sec. 192.03.
    (q) Groundwater means water below the ground surface in a zone of 
saturation.
    (r) Underground source of drinking water means an aquifer or its 
portion:
    (1)(i) Which supplies any public water system as defined in 
Sec. 141.2 of this chapter; or
    (ii) Which contains a sufficient quantity of groundwater to supply 
a public water system; and
    (A) Currently supplies drinking water for human consumption; or
    (B) Contains fewer than 10,000 mg/l total dissolved solids; and
    (2) Which is not an exempted aquifer as defined in Sec. 144.7 of 
this chapter.
    3. Section 192.02 is revised to read as follows:


Sec. 192.02  Standards.

    Control of residual radioactive materials and their listed 
constituents shall be designed \1\ to:
---------------------------------------------------------------------------

    \1\ Because the standard applies to design, monitoring after 
disposal is not required to demonstrate compliance with respect to 
Sec. 192.02(a) and (b).
---------------------------------------------------------------------------

    (a) Be effective for up to one thousand years, to the extent 
reasonably achievable, and, in any case, for at least 200 years, and,
    (b) Provide reasonable assurance that releases of radon-222 from 
residual radioactive material to the atmosphere will not:
    (1) Exceed an average \2\ release rate of 20 picocuries per square 
meter per second, or
---------------------------------------------------------------------------

    \2\ This average shall apply over the entire surface of the 
disposal site and over at least a one-year period. Radon will come 
from both residual radioactive materials and from materials covering 
them. Radon emissions from the covering materials should be 
estimated as part of developing a remedial action plan for each 
site. The standard, however, applies only to emissions from residual 
radioactive materials to the atmosphere.
---------------------------------------------------------------------------

    (2) Increase the annual average concentration of radon-222 in air 
at or above any location outside the disposal site by more than one-
half picocurie per liter.
    (c) Provide reasonable assurance of conformance with the following 
groundwater protection provisions:
    (1) The Secretary shall, on a site-specific basis, determine which 
of the constituents listed in Appendix I to Part 192 are present in or 
reasonably derived from residual radioactive materials and shall 
establish a monitoring program adequate to determine background levels 
of each such constituent in groundwater at each disposal site.
    (2) The Secretary shall comply with conditions specified in a plan 
for remedial action which includes engineering specifications for a 
system of disposal designed to ensure that constituents identified 
under paragraph (c)(1) of this section entering the groundwater from a 
depository site (or a processing site, if residual radioactive 
materials are retained on the site) will not exceed the concentration 
limits established under paragraph (c)(3) of this section (or the 
supplemental standards established under Sec. 192.22) in the uppermost 
aquifer underlying the site beyond the point of compliance established 
under paragraph (c)(4) of this section.
    (3) Concentration limits:
    (i) Concentration limits shall be determined in the groundwater for 
listed constituents identified under paragraph (c)(1) of this section. 
The concentration of a listed constituent in groundwater must not 
exceed:
    (A) The background level of that constituent in the groundwater; or
    (B) For any of the constituents listed in Table 1 to subpart A, the 
respective value given in that Table if the background level of the 
constituent is below the value given in the Table; or
    (C) An alternate concentration limit established pursuant to 
paragraph (c)(3)(ii) of this section.
    (ii)(A) The Secretary may apply an alternate concentration limit 
if, after

[[Page 2866]]

considering remedial or corrective actions to achieve the levels 
specified in paragraphs (c)(3)(i)(A) and (B) of this section, he has 
determined that the constituent will not pose a substantial present or 
potential hazard to human health and the environment as long as the 
alternate concentration limit is not exceeded, and the Commission has 
concurred.
    (B) In considering the present or potential hazard to human health 
and the environment of alternate concentration limits, the following 
factors shall be considered:
    (1) Potential adverse effects on groundwater quality, considering:
    (i) The physical and chemical characteristics of constituents in 
the residual radioactive material at the site, including their 
potential for migration;
    (ii) The hydrogeological characteristics of the site and 
surrounding land;
    (iii) The quantity of groundwater and the direction of groundwater 
flow;
    (iv) The proximity and withdrawal rates of groundwater users;
    (v) The current and future uses of groundwater in the region 
surrounding the site;
    (vi) The existing quality of groundwater, including other sources 
of contamination and their cumulative impact on the groundwater 
quality;
    (vii) The potential for health risks caused by human exposure to 
constituents;
    (viii) The potential damage to wildlife, crops, vegetation, and 
physical structures caused by exposure to constituents;
    (ix) The persistence and permanence of the potential adverse 
effects;
    (x) The presence of underground sources of drinking water and 
exempted aquifers identified under Sec. 144.7 of this chapter; and
    (2) Potential adverse effects on hydraulically-connected surface-
water quality, considering:
    (i) The volume and physical and chemical characteristics of the 
residual radioactive material at the site;
    (ii) The hydrogeological characteristics of the site and 
surrounding land;
    (iii) The quantity and quality of groundwater, and the direction of 
groundwater flow;
    (iv) The patterns of rainfall in the region;
    (v) The proximity of the site to surface waters;
    (vi) The current and future uses of surface waters in the region 
surrounding the site and any water quality standards established for 
those surface waters;
    (vii) The existing quality of surface water, including other 
sources of contamination and their cumulative impact on surface water 
quality;
    (viii) The potential for health risks caused by human exposure to 
constituents;
    (ix) The potential damage to wildlife, crops, vegetation, and 
physical structures caused by exposure to constituents; and
    (x) The persistence and permanence of the potential adverse 
effects.
    (4) Point of compliance: The point of compliance is the location at 
which the groundwater concentration limits of paragraph (c)(3) of this 
section apply. The point of compliance is the intersection of a 
vertical plane with the uppermost aquifer underlying the site, located 
at the hydraulically downgradient limit of the disposal area plus the 
area taken up by any liner, dike, or other barrier designed to contain 
the residual radioactive material.
    (d) Each site on which disposal occurs shall be designed and 
stabilized in a manner that minimizes the need for future maintenance.
    4. Section 192.03 is added to read as follows:


Sec. 192.03  Monitoring.

    A groundwater monitoring plan shall be implemented, to be carried 
out over a period of time commencing upon completion of remedial 
actions taken to comply with the standards in Sec. 192.02, and of a 
duration which is adequate to demonstrate that future performance of 
the system of disposal can reasonably be expected to be in accordance 
with the design requirements of Sec. 192.02(c). This plan and the 
length of the monitoring period shall be modified to incorporate any 
corrective actions required under Sec. 192.04 or Sec. 192.12(c).
    5. Section 192.04 is added to read as follows:


Sec. 192.04  Corrective Action.

    If the groundwater concentration limits established for disposal 
sites under provisions of Sec. 192.02(c) are found or projected to be 
exceeded, a corrective action program shall be placed into operation as 
soon as is practicable, and in no event later than eighteen (18) months 
after a finding of exceedance. This corrective action program will 
restore the performance of the system of disposal to the original 
concentration limits established under Sec. 192.02(c)(3), to the extent 
reasonably achievable, and, in any case, as a minimum shall:
    (a) Conform with the groundwater provisions of Sec. 192.02(c)(3), 
and
    (b) Clean up groundwater in conformance with subpart B, modified as 
appropriate to apply to the disposal site.
    6. Table 1 is added to subpart A to read as follows:

    Table 1 to Subpart A.--Maximum Concentration of Constituents for    
                         Groundwater Protection                         
------------------------------------------------------------------------
      Constituent concentration \1\                   Maximum           
------------------------------------------------------------------------
Arsenic.................................  0.05                          
Barium..................................  1.0                           
Cadmium.................................  0.01                          
Chromium................................  0.05                          
Lead....................................  0.05                          
Mercury.................................  0.002                         
Selenium................................  0.01                          
Silver..................................  0.05                          
Nitrate (as N)..........................  10.                           
Molybdenum..............................  0.1                           
Combined radium-226 and radium-228......  5 pCi/liter                   
Combined uranium-234 and uranium-238 \2\  30 pCi/liter                  
Gross alpha-particle activity (excluding  15 pCi/liter                  
 radon and uranium).                                                    
Endrin (1,2,3,4,10,10-hexachloro-6,7-     0.0002                        
 exposy-1,4,4a,5,6,7,8,8a-octahydro-1,4-                                
 endo,endo-5,8-dimethanonaphthalene).                                   
Lindane (1,2,3,4,5,6-                     0.004                         
 hexachlorocyclohexane, gamma insomer).                                 
Methoxychlor (1,1,1-trichloro-2,2'-bis(p- 0.1                           
 methoxyphenylethane)).                                                 
Toxaphene (C10H10Cl6, technical           0.005                         
 chlorinated camphene, 67-69 percent                                    
 chlorine).                                                             
2,4-D (2,4-dichlorophenoxyacetic acid)..  0.1                           
2,4,5-TP Silvex (2,4,5-                   0.01                          
 trichlorophenoxypropionic acid).                                       
------------------------------------------------------------------------
\1\ Milligrams per liter, unless stated otherwise.                      
\2\ Where secular equilibrium obtains, this criterion will be satisfied 
  by a concentration of 0.044 milligrams per liter (0.044 mg/l). For    
  conditions of other than secular equilibrium, a corresponding value   
  may be derived and applied, based on the measured site-specific ratio 
  of the two isotopes of uranium.                                       

Subpart B--Standards for Cleanup of Land and Buildings Contaminated 
with Residual Radioactive Materials from Inactive Uranium 
Processing Sites

    7. Section 192.11 is amended by revising paragraph (a) and adding 
paragraph (e) to read as follows:


192.11  Definitions.

    (a) Unless otherwise indicated in this subpart, all terms shall 
have the same meaning as defined in subpart A.
* * * * *

[[Page 2867]]

    (e) Limited use groundwater means groundwater that is not a current 
or potential source of drinking water because (1) the concentration of 
total dissolved solids is in excess of 10,000 mg/l, or (2) widespread, 
ambient contamination not due to activities involving residual 
radioactive materials from a designated processing site exists that 
cannot be cleaned up using treatment methods reasonably employed in 
public water systems, or (3) the quantity of water reasonably available 
for sustained continuous use is less than 150 gallons per day. The 
parameters for determining the quantity of water reasonably available 
shall be determined by the Secretary with the concurrence of the 
Commission.
    8. In Sec. 192.12, the introductory text is republished without 
change and paragraph (c) is added to read as follows:


192.12  Standards.

    Remedial actions shall be conducted so as to provide reasonable 
assurance that, as a result of residual radioactive materials from any 
designated processing site:
* * * * *
    (c) The Secretary shall comply with conditions specified in a plan 
for remedial action which provides that contamination of groundwater by 
listed constituents from residual radioactive material at any 
designated processing site (Sec. 192.01(1)) shall be brought into 
compliance as promptly as is reasonably achievable with the provisions 
of Sec. 192.02(c)(3) or any supplemental standards established under 
Sec. 192.22. For the purposes of this subpart:
    (1) A monitoring program shall be carried out that is adequate to 
define backgroundwater quality and the areal extent and magnitude of 
groundwater contamination by listed constituents from residual 
radioactive materials (Sec. 192.02(c)(1)) and to monitor compliance 
with this subpart. The Secretary shall determine which of the 
constituents listed in Appendix I to part 192 are present in or could 
reasonably be derived from residual radioactive material at the site, 
and concentration limits shall be established in accordance with 
Sec. 192.02(c)(3).
    (2) (i) If the Secretary determines that sole reliance on active 
remedial procedures is not appropriate and that cleanup of the 
groundwater can be more reasonably accomplished in full or in part 
through natural flushing, then the period for remedial procedures may 
be extended. Such an extended period may extend to a term not to exceed 
100 years if:
    (A) The concentration limits established under this subpart are 
projected to be satisfied at the end of this extended period,
    (B) Institutional control, having a high degree of permanence and 
which will effectively protect public health and the environment and 
satisfy beneficial uses of groundwater during the extended period and 
which is enforceable by the administrative or judicial branches of 
government entities, is instituted and maintained, as part of the 
remedial action, at the processing site and wherever contamination by 
listed constituents from residual radioactive materials is found in 
groundwater, or is projected to be found, and
    (C) The groundwater is not currently and is not now projected to 
become a source for a public water system subject to provisions of the 
Safe Drinking Water Act during the extended period.
    (ii) Remedial actions on groundwater conducted under this subpart 
may occur before or after actions under Section 104(f)(2) of the Act 
are initiated.
    (3) Compliance with this subpart shall be demonstrated through the 
monitoring program established under paragraph (c)(1) of this section 
at those locations not beneath a disposal site and its cover where 
groundwater contains listed constituents from residual radioactive 
material.

Subpart C--Implementation

    9. In Sec. 192.20, paragraphs (a)(2) and (a)(3) and the first 
sentence of paragraph (b)(l) are revised and paragraphs (a)(4) and 
(b)(4) are added to read as follows:


192.20  Guidance for implementation.

* * * * *
    (a)(1) * * *
    (2) Protection of water should be considered on a case-specific 
basis, drawing on hydrological and geochemical surveys and all other 
relevant data. The hydrologic and geologic assessment to be conducted 
at each site should include a monitoring program sufficient to 
establish background groundwater quality through one or more upgradient 
or other appropriately located wells. The groundwater monitoring list 
in Appendix IX of part 264 of this chapter (plus the additional 
constituents in Table A of this paragraph) may be used for screening 
purposes in place of Appendix I of part 192 in the monitoring program. 
New depository sites for tailings that contain water at greater than 
the level of ``specific retention'' should use aliner or equivalent. In 
considering design objectives for groundwater protection, the 
implementing agencies should give priority to concentration levels in 
the order listed under Sec. 192.02(c)(3)(i). When considering the 
potential for health risks caused by human exposure to known or 
suspected carcinogens, alternate concentration limits pursuant to 
paragraph 192.02(c)(3)(ii) should be established at concentration 
levels which represent an excess lifetime risk, at a point of exposure, 
to an average individual no greater than between 10-4 and 10-
6.

      Table A to Sec.  192.20(a)(2)--Additional Listed Constituents     
Nitrate (as N)                                                          
Molybdenum                                                              
Combined radium-226 and radium-228                                      
Combined uranium-234 and uranium-238                                    
Gross alpha-particle activity (excluding radon and uranium)             

    (3) The plan for remedial action, concurred in by the Commission, 
will specify how applicable requirements of subpart A are to be 
satisfied. The plan should include the schedule and steps necessary to 
complete disposal operations at the site. It should include an estimate 
of the inventory of wastes to be disposed of in the pile and their 
listed constituents and address any need to eliminate free liquids; 
stabilization of the wastes to a bearing capacity sufficient to support 
the final cover; and the design and engineering specifications for a 
cover to manage the migration of liquids through the stabilized pile, 
function without maintenance, promote drainage and minimize erosion or 
abrasion of the cover, and accommodate settling and subsidence so that 
cover integrity is maintained. Evaluation of proposed designs to 
conform to subpart A should be based on realistic technical judgments 
and include use of available empirical information. The consideration 
of possible failure modes and related corrective actions should be 
limited to reasonable failure assumptions, with a demonstration that 
the disposal design is generally amenable to a range of corrective 
actions.
    (4) The groundwater monitoring list in Appendix IX of part 264 of 
this chapter (plus the additional constituents in Table A in paragraph 
(a)(2) of this section) may be used for screening purposes in place of 
Appendix I of part 192 in monitoring programs. The monitoring plan 
required under Sec. 192.03 should be designed to include verification 
of site-specific assumptions used to project the performance of the 
disposal system. Prevention of

[[Page 2868]]

contamination of groundwater may be assessed by indirect methods, such 
as measuring the migration of moisture in the various components of the 
cover, the tailings, and the area between the tailings and the nearest 
aquifer, as well as by direct monitoring of groundwater. In the case of 
vicinity properties (Sec. 192.01(l)(2)), such assessments may not be 
necessary, as determined by the Secretary, with the concurrence of the 
Commission, considering such factors as local geology and the amount of 
contamination present. Temporary excursions from applicable limits of 
groundwater concentrations that are attributable to a disposal 
operation itself shall not constitute a basis for considering 
corrective action under Sec. 192.04 during the disposal period, unless 
the disposal operation is suspended prior to completion for other than 
seasonal reasons.
    (b)(l) Compliance with Sec. 192.12(a) and (b) of subpart B, to the 
extent practical, should be demonstrated through radiation surveys. * * 
*
* * * * *
    (4) The plan(s) for remedial action will specify how applicable 
requirements of subpart B would be satisfied. The plan should include 
the schedule and steps necessary to complete the cleanup of groundwater 
at the site. It should document the extent of contamination due to 
releases prior to final disposal, including the identification and 
location of listed constituents and the rate and direction of movement 
of contaminated groundwater, based upon the monitoring carried out 
under Sec. 192.12(c)(1). In addition, the assessment should consider 
future plume movement, including an evaluation of such processes as 
attenuation and dilution and future contamination from beneath a 
disposal site. Monitoring for assessment and compliance purposes should 
be sufficient to establish the extent and magnitude of contamination, 
with reasonable assurance, through use of a carefully chosen minimal 
number of sampling locations. The location and number of monitoring 
wells, the frequency and duration of monitoring, and the selection of 
indicator analytes for long-term groundwater monitoring, and, more 
generally, the design and operation of the monitoring system, will 
depend on the potential for risk to receptors and upon other factors, 
including characteristics of the subsurface environment, such as 
velocity of groundwater flow, contaminant retardation, time of 
groundwater or contaminant transit to receptors, results of statistical 
evaluations of data trends, and modeling of the dynamics of the 
groundwater system. All of these factors should be incorporated into 
the design of a site-specific monitoring program that will achieve the 
purpose of the regulations in this subpart in the most cost-effective 
manner. In the case of vicinity properties (Sec. 192.01(l)(2)), such 
assessments will usually not be necessary. The Secretary, with the 
concurrence of the Commission, may consider such factors as local 
geology and amount of contamination present in determining criteria to 
decide when such assessments are needed. In cases where 
Sec. 192.12(c)(2) is invoked, the plan should include a monitoring 
program sufficient to verify projections of plume movement and 
attenuation periodically during the extended cleanup period. Finally, 
the plan should specify details of the method to be used for cleanup of 
groundwater.
    10. In Sec. 192.21, the introductory text and paragraph (b) are 
revised, paragraph (f) is redesignated as paragraph (h), and new 
paragraphs (f) and (g) are added to read as follows:


Sec. 192.21  Criteria for applying supplemental standards

    Unless otherwise indicated in this subpart, all terms shall have 
the same meaning as defined in Title I of the Act or in subparts A and 
B. The implementing agencies may (and in the case of paragraph (h) of 
this section shall) apply standards under Sec. 192.22 in lieu of the 
standards of subparts A or B if they determine that any of the 
following circumstances exists:
* * * * *
    (b) Remedial actions to satisfy the cleanup standards for land, 
Sec. 192.12(a), and groundwater, Sec. 192.12(c), or the acquisition of 
minimum materials required for control to satisfy Secs. 192.02(b) and 
(c), would, notwithstanding reasonable measures to limit damage, 
directly produce health and environmental harm that is clearly 
excessive compared to the health and environmental benefits, now or in 
the future. A clear excess of health and environmental harm is harm 
that is long-term, manifest, and grossly disproportionate to health and 
environmental benefits that may reasonably be anticipated.
* * * * *
    (f) The restoration of groundwater quality at any designated 
processing site under Sec. 192.12(c) is technically impracticable from 
an engineering perspective.
    (g) The groundwater meets the criteria of Sec. 192.11(e).
* * * * *
    11. In Sec. 192.22, paragraphs (a) and (b) are revised and 
paragraph (d) is added to read as follows:


192.22  Supplemental standards.

* * * * *
    (a) When one or more of the criteria of Sec. 192.21(a) through (g) 
applies, the Secretary shall select and perform that alternative 
remedial action that comes as close to meeting the otherwise applicable 
standard under Sec. 192.02(c)(3) as is reasonably achievable.
    (b) When Sec. 192.21(h) applies, remedial actions shall reduce 
other residual radioactivity to levels that are as low as is reasonably 
achievable and conform to the standards of subparts A and B to the 
maximum extent practicable.
* * * * *
    (d) When Sec. 192.21(b), (f), or (g) apply, implementing agencies 
shall apply any remedial actions for the restoration of contamination 
of groundwater by residual radioactive materials that is required to 
assure, at a minimum, protection of human health and the environment. 
In addition, when Sec. 192.21(g) applies, supplemental standards shall 
ensure that current and reasonably projected uses of the affected 
groundwater are preserved.
    12. Appendix I is added to part 192 to read as follows:

Appendix I to Part 192--Listed Constituents

Acetonitrile
Acetophenone (Ethanone, 1-phenyl)
2-Acetylaminofluorene (Acetamide, N-9H-fluoren-2-yl-)
Acetyl chloride
1-Acetyl-2-thiourea (Acetamide, N-(aminothioxymethyl)-)
Acrolein (2-Propenal)
Acrylamide (2-Propenamide)
Acrylonitrile (2-Propenenitrile)
Aflatoxins
Aldicarb (Propenal, 2-methyl-2-(methylthio)-,O-
[(methylamino)carbonyl]oxime
Aldrin (1,4:5,8-Dimethanonaphthalene, 1,2,3,4,10,10-hexachloro-
1,4,4a,5,8,8a-
hexahydro(1,4,4a,5,8,8)-)
Allyl alcohol (2-Propen-1-ol)
Allyl chloride (1-Propane,3-chloro)
Aluminum phosphide
4-Aminobiphenyl ([1,1'-Biphenyl]-4-amine)
5-(Aminomethyl)-3-isoxazolol (3(2H)-Isoxazolone,5-(aminomethyl)-)
4-Aminopyridine (4-Pyridineamine)
Amitrole (lH-1,2,4-Triazol-3-amine)
Ammonium vanadate (Vanadic acid, ammonium salt)
Aniline (Benzenamine)
Antimony and compounds, N.O.S.\1\
---------------------------------------------------------------------------

    \1\ The abbreviation N.O.S. (not otherwise specified) signifies 
those members of the general class not specifically listed by name 
in this appendix.

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

[[Page 2869]]

Aramite (Sulfurous acid, 2-chloroethyl 2-[4-(1,1-
dimethylethyl)phenoxy]-1-methylethyl ester)
Arsenic and compounds, N.O.S.
Arsenic acid (Arsenic acid H3AsO4)
Arsenic pentoxide (Arsenic oxide As2O5)
Auramine (Benzamine, 4,4'-carbonimidoylbis[N,N-dimethyl-])
Azaserine (L-Serine, diazoacetate (ester))
Barium and compounds, N.O.S.
Barium cyanide
Benz[c]acridine (3,4-Benzacridine)
Benz[a]anthracene (1,2-Benzanthracene)
Benzal chloride (Benzene, dichloromethyl-)
Benzene (Cyclohexatriene)
Benzenearsonic acid (Arsenic acid, phenyl-)
Benzidine ([1,1'-Biphenyl]-4,4'-diamine)
Benzo[b]fluoranthene (Benz[e]acephananthrylene)
Benzo[j]fluoranthene
Benzo[k]fluoranthene
Benzo[a]pyrene
p-Benzoquinone (2,5-Cyclohexadiene-1,4-dione)
Benzotrichloride (Benzene, (trichloro-
  methyl)-)
Benzyl chloride (Benzene, (chloromethyl)-)
Beryllium and compounds, N.O.S.
Bromoacetone (2-Propanone, 1-bromo-)
Bromoform (Methane, tribromo-)
4-Bromophenyl phenyl ether (Benzene, l-bromo-4-phenoxy-)
Brucine (Strychnidin-10-one, 2,3-dimeth-
  oxy-)
Butyl benzyl phthalate (1,2-Benzenedicarbozylic acid, butyl 
phenylmethyl ester)
Cacodylic acid (Arsinic acid, dimethyl)
Cadmium and compounds, N.O.S.
Calcium chromate (Chromic acid H2CrO4, calcium salt)
Calcium cyanide (Ca(CN)2)
Carbon disulfide
Carbon oxyfluoride (Carbonic difluoride)
Carbon tetrachloride (Methane, tetrachloro-)
Chloral (Acetaldehyde, trichloro-)
Chlorambucil (Benzenebutanoic acid, 4-[bis(2-chloroethyl)amino]-)
Chlordane (4,7-Methano-1H-indene,1,2,4,5,6,7,8,8-octachloro-
2,3,3a,4,7,7a-hexahydro-)
Chlorinated benzenes, N.O.S.
Chlorinated ethane, N.O.S.
Chlorinated fluorocarbons, N.O.S.
Chlorinated naphthalene, N.O.S.
Chlorinated phenol, N.O.S.
Chlornaphazin (Naphthalenamine, N,N'-bis(2-chlorethyl)-)
Chloroacetaldehyde (Acetaldehyde, chloro-)
Chloroalkyl ethers, N.O.S.
p-Chloroaniline (Benzenamine, 4-chloro-)
Chlorobenzene (Benzene, chloro-)
Chlorobenzilate (Benzeneacetic acid, 4-chloro--(4-
chlorophenyl)--hydroxy-, ethyl ester)
p-Chloro-m-cresol (Phenol, 4-chloro-3-methyl)
2-Chloroethyl vinyl ether (Ethene, (2-chloroethoxy)-)
Chloroform (Methane, trichloro-)
Chloromethyl methyl ether (Methane, chloromethoxy-)
-Chloronapthalene (Naphthalene, 2-chloro-)
o-Chlorophenol (Phenol, 2-chloro-)
1-(o-Chlorophenyl)thiourea (Thiourea, (2-chlorophenyl-))
3-Chloropropionitrile (Propanenitrile, 3-chloro-)
Chromium and compounds, N.O.S.
Chrysene
Citrus red No. 2 (2-Naphthalenol, 1-[(2,5-dimethoxyphenyl)azo]-)
Coal tar creosote
Copper cyanide (CuCN)
Creosote
Cresol (Chresylic acid) (Phenol, methyl-)
Crotonaldehyde (2-Butenal)
Cyanides (soluble salts and complexes), N.O.S.
Cyanogen (Ethanedinitrile)
Cyanogen bromide ((CN)Br)
Cyanogen chloride ((CN)Cl)
Cycasin (beta-D-Glucopyranoside, (methyl-ONN-azoxy)methyl)
2-Cyclohexyl-4,6-dinitrophenol (Phenol, 2-cyclohexyl-4,6-dinitro-)
Cyclophosphamide (2H-1,3,2-Oxazaphosphorin-2-amine,N,N-bis(2-
chloroethyl)
tetrahydro-,2-oxide)
2,4-D and salts and esters (Acetic acid, (2,4-dichlorophenoxy)-)
Daunomycin (5,12-Naphthacenedione,8-acetyl-10-[(3-amino-2,3,6-
trideoxy--Llyxo-hexopyranosyl)oxy]-7,8,9,10-tetrahydro-
6,8,11-trihydroxy-1-methoxy-,(8S-cis))
DDD (Benzene, 1,1'-(2,2-dichloroethylidene)bis[4-chloro-)
DDE (Benzene, 1,1-(dichloroethylidene)bis[4-chloro-)
DDT (Benzene, 1,1'-(2,2,2-trichloroethlyidene)bis[4-chloro-)
Diallate (Carbomothioic acid, bis(1-methylethyl)-,S-(2,3-dichloro-2-
propenyl) ester)
Dibenz[a,h]acridine
Dibenz[a,j]acridine
Dibenz[a,h]anthracene
7H-Dibenzo[c,g]carbazole
Dibenzo[a,e]pyrene (Naphtho[1,2,4,5-def)crysene)
Dibenzo[a,h]pyrene (Dibenzo[b,def]crysene)
Dibenzo[a,i]pyrene (Benzo[rst]pentaphene)
1,2-Dibromo-3-chloropropane (Propane, 1,2-dibromo-3-chloro-)
Dibutylphthalate (1,2-Benzenedicarboxylic acid, dibutyl ester)
o-Dichlorobenzene (Benzene, 1,2-dichloro-)
m-Dichlorobenzene (Benzene, 1,3-dichloro-)
p-Dichlorobenzene (Benzene, 1,4-dichloro-)
Dichlorobenzene, N.O.S. (Benzene; dichloro-, N.O.S.)
3,3'-Dichlorobenzidine ([1,1'-Biphenyl]-4,4'-diamine, 3,3'-dichloro-
)
1,4-Dichloro-2-butene (2-Butene, 1,4-dichloro-)
Dichlorodifluoromethane (Methane, dichlorodifluoro-)
Dichloroethylene, N.O.S.
1,1-Dichloroethylene (Ethene, 1,1-dichloro-)
1,2-Dichloroethylene (Ethene, 1,2-dichloro-,(E)-)
Dichloroethyl ether (Ethane, 1,1'-oxybis[2-chloro-)
Dichloroisopropyl ether (Propane, 2,2'-oxybis[2-chloro-)
Dichloromethoxy ethane (Ethane, 1,1'-[methylenebis(oxy)bis[2-chloro-
)
Dichloromethyl ether (Methane, oxybis[chloro-)
2,4-Dichlorophenol (Phenol, 2,4-dichloro-)
2,6-Dichlorophenol (Phenol, 2,6-dichloro-)
Dichlorophenylarsine (Arsinous dichloride, phenyl-)
Dichloropropane, N.O.S. (Propane,
  dichloro-,)
Dichloropropanol, N.O.S. (Propanol, dichloro-,)
Dichloropropene; N.O.S. (1-Propane, dichloro-,)
1,3-Dichloropropene (1-Propene, 1,3-dichloro-)
Dieldrin (2,7:3,6-Dimethanonaphth[2,3-b]oxirene,3,4,5,6,9,9-
hexachloro-1a,2,2a,3,6,6a,7,7a,octahydro-
,(1a,2,2a,3,6,6a
,7,7a)-)
1,2:3,4-Diepoxybutane (2,2'-Bioxirane)
Diethylarsine (Arsine, diethyl-)
1,4 Diethylene oxide (1,4-Dioxane)
Diethylhexyl phthalate (1,2-Benzenedicarboxlyic acid, bis(2-
ethylhexl) ester)
N,N-Diethylhydrazine (Hydrazine, 1,2-diethyl)
O,O-Diethyl S-methyl dithiophosphate (Phosphorodithioic acid, O,O-
diethyl S-methyl ester)
Diethyl-p-nitrophenyl phosphate (Phosphoric acid, diethyl 4-
nitrophenyl ester)
Diethyl phthalate (1,2-Benzenedicarboxylic acid, diethyl ester)
O,O-Diethyl O-pyrazinyl phosphorothioate (Phosphorothioic acid, O,O-
diethyl O-pyrazinyl ester)
Diethylstilbesterol (Phenol, 4,4'-(1,2-diethyl-1,2-ethenediyl)bis-
,(E)-)
Dihydrosafrole (1,3-Benxodioxole, 5-propyl-)
Diisopropylfluorophosphate (DFP) (Phosphorofluoridic acid, bis(1-
methyl ethyl) ester)
Dimethoate (Phosphorodithioic acid, O,O-dimethyl S-[2-(methylamino) 
2-oxoethyl] ester)
3,3'-Dimethoxybenzidine ([1,1'-Biphenyl]-4,4'-diamine, 3,3'-
dimethoxy-)
p-Dimethylaminoazobenzene (Benzenamine, N,N-dimethyl-4-(phenylazo)-)
7,12-Dimethylbenz[a]anthracene (Benz[a]anthracene, 7,12-dimethyl-)
3,3'-Dimethylbenzidine ([1,1'-Biphenyl]-4,4'-diamine, 3,3'-dimethyl-
)
Dimethylcarbamoyl chloride (carbamic chloride, dimethyl-)
1,1-Dimethylhydrazine (Hydrazine, 1,1-dimethyl-)
1,2-Dimethylhydrazine (Hydrazine, 1,2-dimethyl-)
,-Dimethylphenethylamine (Benzeneethanamine, 
,-dimethyl-)
2,4-Dimethylphenol (Phenol, 2,4-dimethyl-)
Dimethylphthalate (1,2-Benzenedicarboxylic acid, dimethyl ester)
Dimethyl sulfate (Sulfuric acid, dimethyl ester)
Dinitrobenzene, N.O.S. (Benzene, dinitro-)
4,6-Dinitro-o-cresol and salts (Phenol, 2-methyl-4,6-dinitro-)
2,4-Dinitrophenol (Phenol, 2,4-dinitro-)
2,4-Dinitrotoluene (Benzene, 1-methyl-2,4-dinitro-)
2,6-Dinitrotoluene (Benzene, 2-methyl-1,3-dinitro-)
Dinoseb (Phenol, 2-(1-methylpropyl)-4,6-dinitro-)
Di-n-octyl phthalate (1,2-Benzenedicarboxylic acid, dioctyl ester)
1,4-Dioxane (1,4-Diethyleneoxide)
Diphenylamine (Benzenamine, N-phenyl-)

[[Page 2870]]

1,2-Diphenylhydrazine (Hydrazine, 1,2-diphenyl-)
Di-n-propylnitrosamine (1-Propanamine,N-nitroso-N-propyl-)
Disulfoton (Phosphorodithioic acid, O,O-diethyl S-[2-
(ethylthio)ethyl] ester)
Dithiobiuret (Thioimidodicarbonic diamide [(H2N)C(S)]2NH)
Endosulfan (6,9,Methano-2,4,3-benzodioxathiepin,6,7,8,9,10,10-
hexachloro-1,5,5a,6,9,9ahexahydro,3-oxide)
Endothall (7-Oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid)
Endrin and metabolites (2,7:3,6-Dimethanonaphth[2,3-
b]oxirene,3,4,5,6,9,9-hexachloro1a,2,2a,3,6,6a,7,7a-octa-
hydro,(1a,2,2a,3,6,6a
,7,7a)-)
Epichlorohydrin (Oxirane, (chloromethyl)-)
Epinephrine (1,2-Benzenediol,4-[1-hydroxy-2-(methylamino)ethyl]-
,(R)-,)
Ethyl carbamate (urethane) (Carbamic acid, ethyl ester)
Ethyl cyanide (propanenitrile)
Ethylenebisdithiocarbamic acid, salts and esters (Carbamodithioic 
acid, 1,2-Ethanediylbis-)
Ethylene dibromide (1,2-Dibromoethane)
Ethylene dichloride (1,2-Dichloroethane)
Ethylene glycol monoethyl ether (Ethanol, 2-ethoxy-)
Ethyleneimine (Aziridine)
Ethylene oxide (Oxirane)
Ethylenethiourea (2-Imidazolidinethione)
Ethylidene dichloride (Ethane, 1,1-
  Dichloro-)
Ethyl methacrylate (2-Propenoic acid, 2-methyl-, ethyl ester)
Ethylmethane sulfonate (Methanesulfonic acid, ethyl ester)
Famphur (Phosphorothioic acid, O-[4-
[(dimethylamino)sulphonyl]phenyl] O,O-dimethyl ester)
Fluoranthene
Fluorine
Fluoroacetamide (Acetamide, 2-fluoro-)
Fluoroacetic acid, sodium salt (Acetic acid, fluoro-, sodium salt)
Formaldehyde (Methylene oxide)
Formic acid (Methanoic acid)
Glycidylaldehyde (Oxiranecarboxyaldehyde)
Halomethane, N.O.S.
Heptachlor (4,7-Methano-1H-indene, 1,4,5,6,7,8,8-heptachloro-
3a,4,7,7a-tetrahydro-)
Heptachlor epoxide (, , and  isomers) 
(2,5-Methano-2H-indeno[1,2-b]-oxirene, 2,3,4,5,6,7,7-heptachloro-
1a,1b,5,5a,6,6a-hexa-hydro-
,(1a,1b,2,5,5a,6
,6a)-)
Hexachlorobenzene (Benzene, hexachloro-)
Hexachlorobutadiene (1,3-Butadiene, 1,1,2,3,4,4-hexachloro-)
Hexachlorocyclopentadiene (1,3-Cyclopentadiene, 1,2,3,4,5,5-
hexachloro-)
Hexachlorodibenzofurans
Heptachlorodibenzo-p-dioxins
Hexachloroethane (Ethane, hexachloro-)
Hexachlorophene (phenol, 2,2'-Methylenebis[3,4,6-trichloro-)
Hexachloropropene (1-Propene, 1,1,2,3,3,3-hexachloro-)
Hexaethyl tetraphosphate (Tetraphosphoric acid, hexaethyl ester)
Hydrazine
Hydrocyanic acid
Hydrofluoric acid
Hydrogen sulfide (H2S)
Indeno(1,2,3-cd)pyrene
Isobutyl alcohol (1-Propanol, 2-methyl-)
Isodrin (1,4,5,8-Dimethanonaphthalene, 1,2,3,4,10,10-hexachloro-
1,4,4a,5,8,8a-hexahydro, 
(1,4,4a,5,8,8a)
-)
Isosafrole (1,3-Benzodioxole, 5-(1-propenyl)-)
Kepone (1,3,4-Metheno-2H-cyclobuta[cd]pentalen-2-one, 
1,1a,3,3a,4,5,5,5a,5b,6-decachlorooctahydro-)
Lasiocarpine (2-Butenoic acid, 2-methyl-,7-[[2,3-dihydroxy-2-(1-
methoxyethyl)-3-methyl-1-oxobutoxy]methyl]-2,3,5,7a-tetrahydro-1H-
pyrrolizin-l-yl ester)
Lead and compounds, N.O.S.
Lead acetate (Acetic acid, lead(2+) salt)
Lead phosphate (Phosphoric acid, lead(2+) salt(2:3))
Lead subacetate (Lead, bis(acetato-O)tetrahydroxytri-)
Lindane (Clohexane, 1,2,3,4,5,6-hexachloro-, 
(1,2,3,4,5,6)-
)
Maleic anhydride (2,5-Furandione)
Maleic hydrazide (3,6-Pyridazinedione, 1,2-dihydro-)
Malononitrile (Propanedinitrile)
Melphalan (L-Phenylalanine, 4-[bis(2-chloroethyl)aminol]-)
Mercury and compounds, N.O.S.
Mercury fulminate (Fulminic acid, mercury(2+) salt)
Methacrylonitrile (2-Propenenitrile, 2-methyl-)
Methapyrilene (1,2-Ethanediamine, N,N-dimethyl-N'-2-pyridinyl-N'-(2-
thienylmethyl)-)
Metholmyl (Ethamidothioic acid, N-[[(methylamino)carbonyl]oxy]thio-, 
methyl ester)
Methoxychlor (Benzene, 1,1'-(2,2,2-trichloroethylidene)bis[4-
methoxy-)
Methyl bromide (Methane, bromo-)
Methyl chloride (Methane, chloro-)
Methyl chlorocarbonate (Carbonchloridic acid, methyl ester)
Methyl chloroform (Ethane, 1,1,1-trichloro-)
3-Methylcholanthrene (Benz[j]aceanthrylene, 1,2-dihydro-3-methyl-)
4,4'-Methylenebis(2-chloroaniline) (Benzenamine, 4,4'-
methylenebis(2-
  chloro-)
Methylene bromide (Methane, dibromo-)
Methylene chloride (Methane, dichloro-)
Methyl ethyl ketone (MEK) (2-Butanone)
Methyl ethyl ketone peroxide (2-Butanone, peroxide)
Methyl hydrazine (Hydrazine, methyl-)
Methyl iodide (Methane, iodo-)
Methyl isocyanate (Methane, isocyanato-)
2-Methyllactonitrile (Propanenitrile, 2-hydroxy-2-methyl-)
Methyl methacrylate (2-Propenoic acid, 2-methyl-, methyl ester)
Methyl methanesulfonate (Methanesulfonic acid, methyl ester)
Methyl parathion (Phosphorothioic acid, O,O-dimethyl O-(4-
nitrophenyl) ester)
Methylthiouracil (4(1H)Pyrimidinone, 2,3-dihydro-6-methyl-2-thioxo-)
Mitomycin C (Azirino[2',3':3,4]pyrrolo[1,2-a]indole-4,7-dione,6-
amino-8-[[(aminocarbonyl) oxy]methyl]-1,1a,2,8,8a,8b-hexahydro-8a-
methoxy-5-methy-, [1aS-
(1a,8,8a,8b)]-)
MNNG (Guanidine, N-methyl-N'-nitro-N-nitroso-)
Mustard gas (Ethane, 1,1'-thiobis[2-chloro-)
Naphthalene
1,4-Naphthoquinone (1,4-Naphthalenedione)
-Naphthalenamine (1-Naphthylamine)
-Naphthalenamine (2-Naphthylamine)
-Naphthylthiourea (Thiourea, 1-naphthalenyl-)
Nickel and compounds, N.O.S.
Nickel carbonyl (Ni(CO)4 (T-4)-)
Nickel cyanide (Ni(CN)2)
Nicotine and salts (Pyridine, 3-(1-methyl-2-pyrrolidinyl)-, (S)-)
Nitric oxide (Nitrogen oxide NO)
p-Nitroaniline (Benzenamine, 4-nitro-)
Nitrobenzene (Benzene, nitro-)
Nitrogen dioxide (Nitrogen oxide NO2)
Nitrogen mustard, and hydrochloride salt (Ethanamine, 2-chloro-N-(2-
chloroethyl)-N-methyl-)
Nitrogen mustard N-oxide and hydrochloride salt (Ethanamine, 
2chloro-N-(2-chloroethyl)N-methyl-, N-oxide)
Nitroglycerin (1,2,3-Propanetriol, trinitrate)
p-Nitrophenol (Phenol, 4-nitro-)
2-Nitropropane (Propane, 2-nitro-)
Nitrosamines, N.O.S.
N-Nitrosodi-n-butylamine (l-Butanamine, N-butyl-N-nitroso-)
N-Nitrosodiethanolamine (Ethanol, 2,2'-(nitrosoimino)bis-)
N-Nitrosodiethylamine (Ethanamine, N-ethyl-N-nitroso-1)
N-Nitrosodimethylamine (Methanamine, N-methyl-N-nitroso-)
N-Nitroso-N-ethylurea (Urea, N-ethyl-N-nitroso-)
N-Nitrosomethylethylamine (Ethanamine, N-methyl-N-nitroso-)
N-Nitroso-N-methylurea (Urea, N-methyl-N-nitroso-)
N-Nitroso-N-methylurethane (Carbamic acid, methylnitroso-, ethyl 
ester)
N-Nitrosomethylvinylamine (Vinylamine, N-methyl-N-nitroso-)
N-Nitrosomorpholine (Morpholine,
 4-nitroso-)
N-Nitrosonornicotine (Pyridine, 3-(1-nitroso-2-pyrrolidinyl)-, (S)-)
N-Nitrosopiperidine (Piperidine, 1-nitroso-)
Nitrosopyrrolidine (Pyrrolidine, 1-nitroso-)
N-Nitrososarcosine (Glycine, N-methyl-N-nitroso-)
5-Nitro-o-toluidine (Benzenamine, 2-methyl-5-nitro-)
Octamethylpyrophosphoramide (Diphosphoramide, octamethyl-)
Osmium tetroxide (Osmium oxide OsO4, (T-4)-)
Paraldehyde (1,3,5-Trioxane, 2,4,6-tri
methyl-)
Parathion (Phosphorothioic acid, O,O-diethyl O-(4-nitrophenyl) 
ester)
Pentachlorobenzene (Benzene, pentachloro-)
Pentachlorodibenzo-p-dioxins
Pentachlorodibenzofurans
Pentachloroethane (Ethane, pentachloro-)
Pentachloronitrobenzene (PCNB) (Benzene, pentachloronitro-)
Pentachlorophenol (Phenol, pentachloro-)
Phenacetin (Acetamide, N-(4-ethoxyphenyl)-)
Phenol
Phenylenediamine (Benzenediamine)
Phenylmercury acetate (Mercury, (acetato-O)phenyl-)

[[Page 2871]]

Phenylthiourea (Thiourea, phenyl-)
Phosgene (Carbonic dichloride)
Phosphine
Phorate (Phosphorodithioic acid, O,O-diethyl S-[(ethylthiomethyl] 
ester)
Phthalic acid esters, N.O.S.
Phthalic anhydride (1,3-isobenzofurandione)
2-Picoline (Pyridine, 2-methyl-)
Polychlorinated biphenyls, N.O.S.
Potassium cyanide (K(CN))
Potassium silver cyanide (Argentate(l-), bis(cyano-C)-, potassium)
Pronamide (Benzamide, 3,5-dichloro-N-(1,1-dimethyl-2-propynyl)-)
1,3-Propane sultone (1,2-Oxathiolane, 2,2-dioxide)
n-Propylamine (1-Propanamine)
Propargyl alcohol (2-Propyn-1-ol)
Propylene dichloride (Propane, 1,2-
dichloro-)
1,2-Propylenimine (Aziridine, 2-methyl-)
Propylthiouracil (4(1H)-Pyrimidinone, 2,3-dihydro-6-propyl-2-thioxo-
)
Pyridine
Reserpinen (Yohimban-16-carboxylic acid, 11,17-dimethoxy-18-[(3,4,5-
trimethoxybenzoyl)oxy]-smethyl ester, (3,16 
,17,18,20)-)
Resorcinol (1,3-Benzenediol)
Saccharin and salts (1,2-Benzisothiazol-3(2H)-one, 1,1-dioxide)
Safrole (1,3-Benzodioxole, 5-(2-propenyl)-)
Selenium and compounds, N.O.S.
Selenium dioxide (Selenious acid)
Selenium sulfide (SeS2)
Selenourea
Silver and compounds, N.O.S.
Silver cyanide (Silver cyanide Ag(CN))
Silvex (Propanoic acid, 2-(2,4,5-trichlorophen
oxy)-)
Sodium cyanide (Sodium cyanide Na(CN))
Streptozotocin (D-Glucose, 2-deoxy-2-
[[methylnitrosoamino)carbonyl]amino]-)
Strychnine and salts (Strychnidin-10-one)
TCDD (Dibenzo[b,e][1,4]dioxin, 2,3,7,8-tetrachloro-)
1,2,4,5-Tetrachlorobenzene (Benzene, 1,2,4,5-tetrachloro-)
Tetrachlorodibenzo-p-dioxins
Tetrachlorodibenxofurans
Tetrachloroethane, N.O.S. (Ethane, tetrachloro-, N.O.S.)
1,1,1,2-Tetrachloroethane (Ethane, 1,1,1,2-tetrachloro-)
1,1,2,2-Tetrachloroethane (Ethane, 1,1,2,2-tetrachloro-)
Tetrachloroethylene (Ethene, tetrachloro-)
2,3,4,6-Tetrachlorophenol (Phenol, 2,3,4,6-tetrachloro-)
Tetraethyldithiopyrophosphate (Thiodiphosphoric acid, tetraethyl 
ester)
Tetraethyl lead (Plumbane, tetraethyl-)
Tetraethyl pyrophosphate (Diphosphoric acid, tetraethyl ester)
Tetranitromethane (Methane, tetranitro-)
Thallium and compounds, N.O.S.
Thallic oxide (Thallium oxide Tl2O3)
Thallium (I) acetate (Acetic acid, thallium (1+) salt)
Thallium (I) carbonate (Carbonic acid, dithallium (1+) salt)
Thallium (I) chloride (Thallium chloride TlCl)
Thallium (I) nitrate (Nitric acid, thallium (1+) salt)
Thallium selenite (Selenius acid, dithallium (1+) salt)
Thallium (I) sulfate (Sulfuric acid, thallium (1+) salt)
Thioacetamide (Ethanethioamide)
3,Thiofanox (2-Butanone, 3,3-dimethyl-1-(methylthio)-, O-
[(methylamino)carbonyl] oxime)
Thiomethanol (Methanethiol)
Thiophenol (Benzenethiol)
Thiosemicarbazide (Hydrazinecarbothioamide)
Thiourea
Thiram (Thioperoxydicarbonic diamide [(H2N)C(S)]2S2, 
tetramethyl-)
Toluene (Benzene, methyl-)
Toluenediamine (Benzenediamine, ar-methyl-)
Toluene-2,4-diamine (1,3-Benzenediamine, 4-methyl-)
Toluene-2,6-diamine (1,3-Benzenediamine, 2-methyl-)
Toluene-3,4-diamine (1,2-Benzenediamine, 4-methyl-)
Toluene diisocyanate (Benzene, 1,3-diisocyanatomethyl-)
o-Toluidine (Benzenamine, 2-methyl-)
o-Toluidine hydrochloride (Benzenamine, 2-methyl-, hydrochloride)
p-Toluidine (Benzenamine, 4-methyl-)
Toxaphene
1,2,4-Trichlorobenzene (Benzene, 1,2,4-trichloro-)
1,1,2-Trichloroethane (Ethane, 1,1,2-trichloro-)
Trichloroethylene (Ethene,trichloro-)
Trichloromethanethiol (Methanethiol, trichloro-)
Trichloromonofluoromethane (Methane, trichlorofluoro-)
2,4,5-Trichlorophenol (Phenol, 2,4,5-trichloro-)
2,4,6-Trichlorophenol (Phenol, 2,4,6-trichloro-)
2,4,5-T (Acetic acid, 2,4,5- trichloro-
  phenoxy-)
Trichloropropane, N.O.S.
1,2,3-Trichloropropane (Propane, 1,2,3-trichloro-)
O,O,O-Triethyl phosphorothioate (Phosphorothioic acid, O,O,O-
triethyl ester)
Trinitrobenzene (Benzene, 1,3,5-trinitro-)
Tris(1-aziridinyl)phosphine sulfide (Aziridine, 
1,1',1''phosphinothioylidynetris-))
Tris(2,3-dibromopropyl) phosphate (1-Propanol, 2,3-dibromo-, 
phosphate (3:1))
Trypan blue (2,7-Naphthalendisulfonic acid, 3,3'-[(3,3'-
dimethyl[1,1'-biphenyl]-4,4'-diyl)bis(azo)]bis(5-amino-4-hydroxy-, 
tetrasodium salt)
Uracil mustard (2,4-(1H,3H)-Pyrimidinedione, 5-[bis(2-
chloroethyl)amino]-)
Vanadium pentoxide (Vanadium oxide V2O5)
Vinyl chloride (Ethene, chloro-)
Wayfarin (2H-1-Benzopyran-2-one, 4-hydroxy-3-(3-oxo-1-phenlybutyl)-)
Zinc cyanide (Zn(CN)2)
Zinc phosphide (Zn3P2)

[FR Doc. 95-546 Filed 1-10-95; 8:45 am]
BILLING CODE 6560-50-P`