Standards for the Management and Use of Slag Residues Derived >From HTMR Treatment of K061, K062, and F006 Wastes

[Federal Register: December 29, 1994]

ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 261, 266, and 268

[SW-FRL-5127-2]
RIN 2050-AE15

Standards for the Management and Use of Slag Residues Derived
>From HTMR Treatment of K061, K062, and F006 Wastes

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule and request for comment.

SUMMARY: The Environmental Protection Agency (EPA or the Agency) is
proposing to allow materials resulting from the treatment of certain
hazardous wastes to be used as a product in road construction and as an
anti-skid/deicing material on road surfaces. These materials are
residues (``slags'') generated from the treatment of pollution control
dusts resulting from scrap metal recycling (electric arc furnace dust).
The Agency evaluated the potential risks that might arise from the use
of these ``slags'', and determined that these uses do not present a
significant risk. This action would reclassify these treated materials
as nonhazardous and allow these uses, but only if the toxic metals in
the waste are reduced to safe levels by treatment.
The Agency is proposing this action to clarify two seemingly
inconsistent parts of the regulations governing residual materials
generated from the treatment of hazardous wastes. This rule clarifies
what uses of the treatment residues are allowed, and specifies what
conditions must be met for these materials to be used in this manner.
Furthermore, this action partially fulfills a settlement agreement
entered into by the Agency with the Natural Resources Defense Council
(NRDC) and the Hazardous Waste Treatment Council (HWTC) to resolve the
apparent inconsistency in the regulations.
The Agency believes these proposed actions will promote recycling
and resource recovery in two ways. This action will directly encourage
the recovery of metals from the hazardous electric arc furnace dust and
other metal wastes by allowing the ``slag'' residuals to be used in a
beneficial and environmentally sound way. Furthermore, this proposed
rule will encourage the recycling of scrap metal by helping to reduce
the costs that result from the treatment and disposal of the electric
arc furnace dust. The Agency believes that this rule would satisfy the
goals of resource recovery, while also ensuring protection of human
health and the environment.

DATES: EPA will accept public comments on this proposed rule until
February 13, 1995. Comments postmarked after this date will be marked
``late'' and may not be considered.

ADDRESSES: The public must send an original and two copies of their
comments to EPA RCRA Docket Number F-94-SRTP-FFFFF, room 2616 (Mail
Code 5305), 401 M Street S.W., Washington, DC 20460. The docket is open
from 9:00 a.m. to 4:00 p.m., Monday through Friday, except on Federal
holidays. The public must make an appointment to review docket
materials by calling (202) 260-9327. A maximum of 100 pages may be
copied at no cost. Additional copies cost $0.15 per page.

FOR FURTHER INFORMATION CONTACT: For general information contact the
RCRA Hotline, toll free at (800) 424-9346, or at (703) 412-9810. For
specific questions concerning this notice, contact Narendra Chaudhari,
Office of Solid Waste (Mail Code 5304), U.S. Environmental Protection
Agency, 401 M Street, S.W., Washington, DC 20460, (202) 260-4787.

SUPPLEMENTARY INFORMATION:

I. Background

A. Existing Regulations for Hazardous Wastes Used in a Manner
Constituting Disposal

Currently, hazardous wastes that are used in a manner constituting
disposal (applied to or placed on land), including waste-derived
products that are produced in whole or in part from hazardous wastes
and used in a manner constituting disposal, are not subject to
hazardous waste disposal regulations provided the products produced
meet two conditions. First, the hazardous wastes must undergo a
chemical reaction in the course of becoming products so as to be
inseparable by physical means (see Sec. 266.20(b)). A second condition
for exemption is that the waste-derived products must meet best
demonstrated available technology (BDAT) treatment standards under the
land disposal restrictions program for every prohibited hazardous waste
that they contain before they are placed on land (see Sec. 266.20(b)).
The exemption in Sec. 266.20 is used for slag residues (slags)
generated from the treatment of hazardous waste K061 (and, to a limited
extent, K062 and F006) using high temperature metal recovery (HTMR)
processes. Section 266.20 is applicable because the majority of this
slag is used in highway construction materials (e.g., as road subbase),
and a limited amount is also used by directly applying it to road
surfaces (i.e., top grade and as an anti-skid or deicing agent). (See
56 FR 15020, April 12, 1991.)
On August 19, 1991 and August 18, 1992 (see 56 FR 41164 and 57 FR
37194), EPA finalized ``generic exclusions'' for nonwastewater slag
residues generated from the HTMR treatment of several metal-bearing
hazardous wastes (K061, K062, and F006). These HTMR slag residues are
excluded from the hazardous waste regulations provided they meet
designated concentration levels (generic exclusion levels) for 13
metals, are disposed of in Subtitle D units, and exhibit no
characteristics of hazardous waste (see Sec. 261.3(c)(2)(ii)(C)). The
generic exclusion levels for the metals were based on the use of the
EPA Composite Model for Landfills (EPACML), which predicts the
potential for groundwater contamination from wastes that are placed in
a landfill. EPA limited the generic exclusion to residues disposed of
in a Subtitle D unit because, at that time, the Agency could not
properly evaluate concerns over potential releases to other media
resulting from uses of the HTMR slag as product, especially as an antiskid
material on road surfaces (see 56 FR 41164, August 19,1991).
As EPA noted in the final rule for the initial generic exclusion
for K061 residues (see 56 FR 41164, August 19, 1991), the use of HTMR
residues as anti-skid material was not prohibited, provided the residue
meets the exemption conditions given in Sec. 266.20. EPA also noted in
the same notice that it would further evaluate the uses of K061 HTMR
residues that constitute disposal, and would consider amendments to
Sec. 266.20 for HTMR slags that might require further controls on such
uses.

B. Summary of Petition and Settlement Agreement

The Natural Resources Defense Council (NRDC) and the Hazardous
Waste Treatment Council (HWTC) filed a petition for review challenging
EPA's decision not to apply ``generic exclusion levels''--levels at
which K061 slags are deemed nonhazardous--to K061 slags used as wastederived
``products'' and applied to or placed on land. The generic
exclusion levels established for some metals in the K061 HTMR slags are
lower than the BDAT standards that apply to K061. Therefore, while the
generic exclusion requires that the nonhazardous K061 slag that meets
exclusion levels be disposed of in a Subtitle D unit, K061 HTMR slag
that may exhibit metal levels above the exclusion levels (but below
BDAT) may be used as a product in a manner constituting disposal under
the exemption in Sec. 266.20(b). The petitioners pointed out the
seeming anomaly of the slag used in an uncontrolled manner being
effectively subject to lesser standards than slag disposed in a
controlled landfill.
On August 13, 1993, EPA entered into a settlement agreement with
these petitioners which would address their concerns through two
separate notice-and-comment rulemakings. EPA agreed to propose the
first rule within 6 months of the settlement date (and issue a final
rule within 12 months) to either establish generic exclusion levels for
``non-encapsulated'' uses of K061 slags, or effectively prohibit such
uses of K061 slags on the land. EPA also agreed to propose a second
rule within 16 months of the settlement date (and issue a final rule
within 28 months), to establish generic exclusion levels for
encapsulated uses of K061 slags on the land. The agreement specified
that the generic exclusion levels for K061 slags will be based on an
evaluation of the potential risks to human health and the environment
from the use of K061 slags as waste-derived products, taking into
account all relevant pathways of exposure.

C. Implementation of Settlement Agreement

This action represents the second proposed rule required under the
settlement agreement. EPA has promulgated the first rules required
under the settlement agreement. (See 59 FR 8583, February 23, 1994
(proposed) and 59 FR 43496, August 24, 1994 (final)). The final rule
will effectively prohibit, beginning on February 24, 1995, anti-skid/
deicing uses of HTMR slags derived from K061, K062, and F006, as wastederived
products placed on land. Today's proposal contains EPA's riskbased
determinations for all major K061, K062, and F006 HTMR slag uses,
including anti-skid/deicing uses, and thus implements the remaining
portion of the agreement.

II. Overview of Production, Processing, and Uses

A. Production of HTMR Slags

According to information available to EPA, HTMR slags are byproducts
of metal recovery operations (which involve recovery of metals
from metal-bearing hazardous wastes) produced primarily at two
facilities, Horsehead Resource Development Company, Inc. (HRD) and
International Metal Reclamation Company (Inmetco). HRD is currently the
major generator of HTMR slags which are at issue in this proposed rule.
In 1992, HRD processed 376,000 tons of electric arc furnace (EAF) dust,
which is reportedly 68 percent of the EAF dust generated domestically.
>From this amount of EAF dust, HRD produced 120,000 tons of zinc
calcine, 19,000 tons of lead concentrate, and 237,000 tons of slag (see
EPA's Report to Congress on Metal Recovery, Environmental Regulation &
Hazardous Waste; EPA 530-R-93-018). Inmetco provided information that
it processed a total of 58,100 tons of wastes in 1993, recovering
22,196 tons of metals and producing 15,000 tons of slag (See docket for
information submitted by Inmetco at a meeting with EPA on March 10,
1994).

B. Process Description

There are a number of HTMR processes, all of which are multi-step
processes. The rotary kiln is the HTMR process primarily used to
recover metals from K061, K062, and F006 wastes. The process steps are
generally these: (1) wastes are mixed with coal or coke and fluxes to
prepare feed materials, (2) high temperature processing is used to
reduce metal oxides to their metallic form, 3) volatile metals
(primarily cadmium, zinc, and lead) are recovered by collection
systems, and 4) residual materials are discharged from the process and
cooled to form a slag (see BDAT Background Document for K061). It
should be noted that not all metal-bearing hazardous wastes are
amenable to recovery by HTMR processes, possibly because their metal
content is too low or because of significant quantities of impurities
or contaminants that cannot be removed due either to economic or
technical limitations. Therefore, metal reclaimers usually set
specifications for materials that they will accept for processing (see
EPA's Report to Congress on Metal Recovery, Environmental Regulation &
Hazardous Waste; EPA 530-R-93-018).

C. Properties and Uses of HTMR Slags

According to information provided by the generators on the
physical/chemical properties of HTMR slags (see RCRA docket), these
slags are highly dense, chemically stable (inert), and highly durable
(resistant to breakdown). These are all properties which the generators
claim make HTMR slags desirable construction materials.
HTMR slags are primarily used as subbase materials (e.g., in
construction of roads, parking lots, and driveways) and as additive
ingredients in cement or concrete/asphalt mixtures. Because the subbase
is covered by a relatively hard/impermeable material and cement or
concrete/asphalt mixtures lock in any additive ingredients, EPA
considers these uses of HTMR slags to be ``encapsulated'' uses. A
smaller portion of HTMR slags (believed to be less than 25 percent) are
used as anti-skid/deicing materials, as top grade or surfacing
materials (e.g., in construction of roads), and for other similar uses.
Because anti-skid/deicing materials are dispersed freely on roads
(during icy or snowy conditions to provide traction for vehicles) and
top grade materials result in uncovered (unpaved) roads, parking lots,
driveways, and the like, EPA considers these uses of HTMR slags to be
``non-encapsulated'' uses.

III. Proposed Standards for the Management and Use of HTMR Slags

EPA is proposing that risk-based generic exclusion levels in
Sec. 261.3(c)(2)(ii)(C), in addition to being exclusion standards for
disposing HTMR slags derived from hazardous wastes K061, K062, and F006
in a Subtitle D unit, also become exclusion standards for managing
these slags and for using these slags as follows: 1) covered subbase
materials (e.g., in construction of paved roads, parking lots, and
driveways), 2) additive ingredients in cement or concrete/asphalt
mixtures, 3) top grade or surfacing materials (e.g., in construction of
roads, parking lots, and driveways), and 4) anti-skid/deicing
materials.
The Agency is proposing this action for the following reasons.
Based on the results of a very conservative risk assessment completed
by EPA for the relevant management practices and end-uses of HTMR slags
(see Section IV. for details), EPA has tentatively determined that the
wastepile, transport, road subbase, and landfill waste management
scenarios for HTMR-derived slags do not require regulation in order to
protect human health and the environment, if these slags meet the
generic exclusion levels. In addition, EPA is proposing that use of
HTMR slags as additive ingredients in cement or concrete/asphalt
mixtures would also not require regulation, if these slags meet the
generic exclusion levels. This is primarily because the cement or
concrete/asphalt mixtures would mix with and chemically bind or
encapsulate the portion of HTMR slags that are added, and any
significant releases of slag constituents into the environment are
unlikely. Finally, the risk assessment results, which are based on very
conservative release and exposure assumptions, indicated little
potential risk for the top grade and anti- skid/deicing end-uses of
HTMR slags that meet the generic exclusion levels. Therefore, EPA is
also proposing that uses of HTMR slags as top grade and anti-skid/
deicing materials would also not require regulation, if these slags
meet the generic exclusion levels.
As a consequence of the above proposed changes, EPA is also
proposing to amend the existing regulations under Sec. 266.20 that
conditionally exempt hazardous waste-derived products used in a manner
constituting disposal from RCRA Subtitle C regulation. Specifically,
the language of Sec. 266.20 would be revised to prohibit the uses of
products containing HTMR slags derived from hazardous wastes K061,
K062, and F006 when these slags are still hazardous wastes, i.e.,
contain hazardous constituents at concentrations exceeding the
exclusion levels. This prohibition implements RCRA section 3004(g)(5)
and 3004(m), which require EPA to prohibit land disposal of hazardous
wastes that have not been pre-treated so as to minimize the short-term
and long-term threats posed by their land disposal. In addition, EPA is
including a cross-reference in the table ``Treatment Standards for
Hazardous Wastes'' in Sec. 268.40 (the Land Disposal Restriction
treatment standards) which notes the changes concerning utilization of
HTMR slags in Secs. 261.3 and 266.20.
As described in section IV.C, the Agency is also taking this
opportunity to update the generic exclusion levels to reflect the
changes in the drinking water Maximum Contaminant Levels (MCLs) for
some of the metals of concern. Therefore, the Agency is proposing to
amend the generic exclusion levels for antimony, beryllium, and nickel.
EPA requests comments on the proposed changes. EPA also requests
comments on the data used in the risk assessment, the methodology and
assumptions used in the risk assessment, and other analysis supporting
the proposed rule. Further, EPA requests comments on whether the uses
of HTMR slags identified in this proposal are the only uses in practice
or whether there are other uses practiced or planned. If EPA is alerted
to other significant uses, the Agency could use the information to
determine whether or not further analysis of those uses would be
required.

IV. Overview of Risk Assessment Supporting This Proposal

EPA performed a very conservative assessment of the potential risks
to human health and the environment from the relevant management
practices and uses of K061, K062, and F006 HTMR slags. This section
summarizes the methods and results of EPA's risk assessment. A more
detailed presentation of the risk assessment and uncertainties involved
is provided in a technical background document entitled ``Assessment of
Potential Risks to Human Health and the Environment from Management and
Uses of HTMR Slags,'' which is included in the docket for this proposed
rulemaking.

A. Methodology of Risk Assessment

EPA's methodology consisted of four primary steps. First, a
lifecycle analysis for the HTMR slags was performed, starting from the
point of manufacture and ending at the point of disposal, to identify
potential contaminant release scenarios (air, ground water, surface
water, and soil) associated with slag management, use, and disposal
practices. Second, based on the release scenarios, exposure pathways
and receptor locations relevant to contaminants in HTMR slags were
identified. Third, appropriate release, fate, and transport models were
used to compute contaminant concentrations at receptor points for each
release and exposure pathway. Finally, the media-specific
concentrations for air, ground water, surface water, and soil were
compared to the appropriate human health and ecological effects
reference concentrations to determine the quantitative risks from
exposures to contaminants in HTMR slags.
EPA focused on selecting high-end values for use in the models to
estimate the individual risk for those persons at the upper end (>90th
percentile of the population distribution) of the risk distribution.
The Agency chose this very conservative approach in order to identify
any pathways or chemicals which would warrant a more in depth risk
assessment and characterization. A summary of the data sources and risk
assessment methodology for HTMR slags is provided below.

Sources of Constituents Data for HTMR Slags
The constituents of concern in HTMR slags were identified in the
Land Disposal Restrictions for Electric Arc Furnace Dust (K061) - Final
Rule (56 FR No. 160, p 41164) and supported by the Best Demonstrated
Available Technology (BDAT) Background Document for K061 (US EPA,
1988). Specifically, the K061 Final Rule identified fourteen metals
requiring BDAT treatment standards for K061, including: antimony,
arsenic, barium, beryllium, cadmium, chromium, lead, mercury, nickel,
selenium, silver, thallium, vanadium, and zinc. However, for various
reasons discussed in the K061 Final Rule, EPA promulgated the standard
for vanadium as ``reserved.''
For the purposes of the risk assessment, total concentrations of
constituents of concern in HTMR residuals were based on the EPAcollected
data base presented in the BDAT Background Document for K061
(US EPA, 1988). For each constituent of concern, the 95th percentile
upper confidence limit of the mean (95th UCLM) was calculated for the
total metal concentration (in ppm or, equivalently, mg constituent per
kg HTMR residual). EPA selected this value to represent a reasonable
high-end measure of constituent concentrations in HTMR residuals. Table
1 presents the total concentrations and summary statistics for that
data set, including maximum concentration, mean, and the range of
concentrations.
For exposure scenarios involving HTMR leachate (e.g., landfilling
of HTMR-derived slag), the leachate concentration was assumed to be
equal to the maximum levels allowed under the generic exclusion
established in the K061 final rule. Table 1 also presents the generic
exclusion levels (in mg/L).

Table 1.--Summary Statistics for Constituent Concentrations for HTMR Residuals

Total constituent concentrations in HTMR residuals
fromrotary kiln incinerator Generic exclusion

Constituent --------------------------------------------------------- levels for

Range (ppm) Mean (ppm) 95UCLM (ppm) leachate (mg/L)

Antimony............................ 111-405 195 266 0.10
Arsenic............................. 75-113 86 98 0.50
Barium.............................. 331-467 374 408 7.6
Beryllium........................... 1.7-4 2 3 0.01
Cadmium............................. <15 <15 <15 0.05
Total Chromium...................... 205-978 612 797 0.33
Lead................................ 365-4270 1926 2863 0.15
Mercury............................. <0.1 <0.1 <0.1 0.009
Nickel.............................. 422-952 588 727 1.0
Selenium............................ 2.5-8.8 5 6 0.16
Silver.............................. 32-59 39 46 0.30
Thallium............................ <0.5-<1.0 <1 <1 0.02
Zinc................................ 4550-27400 14634 22117 70

Note: Concentration of chromium VI was estimated to be 112f total chromium, based on leaching data for total

chromium.

2. Release, Fate, and Transport Models
To assess the risks from relevant management practices and uses of
HTMR slags, EPA used fate and transport models to compute contaminant
concentrations at exposure points for each release and exposure
scenario. EPA used the appropriate algorithms from the MMSOILS model, a
multimedia contaminant fate, transport, and exposure model, to simulate
fate and transport of metals in HTMR slags through overland and
subsurface transport. The overland transport of metals in HTMR slags
incorporated transport to nearby soils and surface water (including
dissolved contaminants and contaminants sorbed to slag particles). EPA
used the Fugitive Dust Model (FDM) to compute dispersion and transport
of particulates in air from ground-based sources. FDM is a computerized
air quality model which was specifically designed to calculate air
concentrations from fugitive dust sources. The model is based on the
Gaussian plume algorithm for computing air concentrations, adapted to
incorporate a gradient-transfer deposition algorithm. The MINTEQ metals
speciation model was used to estimate soil adsorption coefficients for
the metal constituents in HTMR slags whenever possible. The MINTEQ
model is an aqueous speciation geochemical model which estimates metal
adsorption as a function of Ph, metal concentrations in the dissolved
phase, iron oxide content of potential sorbents, organic matter content
of potential sorbents, pore water chemistry, and temperature. Further
details of the models used are provided in the docket for this proposed
rulemaking.
3. Sources of Environmental Releases
EPA identified the potential sources of metals releases from HTMR
slags based on known management practices and end-uses of HTMR slags:
disposal in landfills, storage in wastepiles, transportation in trucks,
use as road construction material underlying pavement (subbase or base
material), use as additive ingredient in cement or aggregate in
concrete/asphalt mixtures, use as road surface material (top grade),
and use as anti- skid/deicing agent on road surfaces. Potential
releases under these scenarios are described below.
a. Wastepile--Four practices associated with the generation and
management of wastepiles of HTMR slags may result in potential releases
to the environment: (1) outdoor storage of an uncovered wastepile, (2)
adding HTMR slags to the wastepile, (3) loading/unloading operations
associated with transport of the wastepile, and (4) transport of slags
from the facility to points of use.
The HTMR slags generated at the manufacturing facility may be
stored outside in an uncovered wastepile at the facility until it is
transported offsite. Since the wastepiles are uncovered, air releases
may occur if particulates from the wastepile become entrained in the
atmosphere. The slag particulates also may be eroded from the wastepile
as a result of wind and rain. In addition, since the slags could be
stored directly on top of the soil (i.e., no liner), release to the
ground water may occur if metals from the slags leach as a result of
precipitation.
As slags are added to the wastepile, the resulting disturbance may
cause particles to become entrained in the atmosphere. Particulate
emissions of slag material may also be caused by the loading/unloading
operations associated with transport vehicles. Finally, particulate
emissions of slag material may result from the transport of the
wastepile, assuming that the transport vehicles are not fully covered.
b. Road Subbase--The HTMR slags may be transported from the
manufacturing facility to a site for use as a road subbase material.
The subbase layer is then covered by a relatively impermeable road
surfacing material, typically asphalt. Although there is potential for
environmental releases from the subbase material prior to road
surfacing and when road surfaces are broken up for repair, such
releases are expected to be short- term, temporary events, and any
releases would be relatively minor. Therefore, atmospheric and erosion
releases were not modeled for the use of HTMR slags as a road subbase
material. However, even while the subbase is covered, the metals in the
slag could potentially be released during a high water table event. In
this circumstance, the water table may become elevated to the extent
that it contacts and saturates the road subbase layer. The metals in
the slag could leach from the road subbase, pass through the
unsaturated soil zone, and discharge into the groundwater.
c. Additives in Cement or Concrete/Asphalt Mixtures--HTMR slag
material may also be used as an ingredient in the production of cement
(as a source of iron in cement kilns). Alternatively, the slag may be
used as aggregate in the production of concrete or asphalt. In these
uses, the cement or concrete/asphalt mixtures would mix with and
chemically bind or encapsulate the portion of HTMR slags that are
added. Therefore, there is not likely to be any significant releases
from this use by any scenario. There is the possibility, if pieces of
cement or concrete/asphalt are ultimately disposed in a landfill, that
environmental releases may occur. This type of scenario was considered
under disposal of HTMR slags directly in a landfill; this represents a
``worst case'' for the concrete/asphalt mixtures because the landfill
was assumed to contain the HTMR slags, and not slags mixed with or
encapsulated in concrete or asphalt.
d. Top Grade--The HTMR slags may be used as a top grade material,
as the surface material for an unpaved road. Atmospheric releases of
the slag particulate as a result of vehicular traffic, particulate
releases resulting from both wind erosion and surface runoff, and
contaminant releases from the top grade layer resulting from leaching
processes are all possible release pathways, and were considered in the
Agency's assessment.
e. Anti-Skid/Deicing--The HTMR slags can be used as anti- skid/
deicing agents on ice and/or snow covered roads. A thin layer of the
slag material is spread over the road surface in an effort to provide
better traction for vehicle tires. During warm periods in which the
snow and ice melt, the metals present in the slag material may leach
from an unpaved road through the unsaturated zone and into the
surficial aquifer. In addition, the slag material may erode from the
site by wind and rain and be deposited on adjacent property. Lastly,
slag particulates may become entrained in the atmosphere as a result of
vehicle traffic, and may result in atmospheric emissions similar to
that of the top grade scenario.
f. Disposal in Landfill--One of the lifecycle phases considered in
this analysis involves disposal of slag in a solid waste landfill. The
potential leaching of constituents from the slag in the landfill into
groundwater was evaluated previously in the rulemaking that established
the generic exclusion levels for HTMR slag (see August 18, 1992, 57 FR
37194). Other potential release scenarios from the landfill that were
identified include: (1) erosion of particulates from the landfill, and
(2) air releases and deposition to nearby soils. Particulates from slag
may be eroded from the landfill as a result of the forces of wind and
rain. The eroded material may ultimately be deposited onto a nearby
residential plot of land or into a nearby surface water body.
Particulates entrained in the atmosphere as a result of waste
management activities at the landfill may also be transported to offsite
receptors.
4. Exposure Pathways
EPA considered various direct and indirect exposure pathways for
HTMR slag materials and believes that the potential for risk from most
indirect pathways (e.g., food chain pathways) would not be significant.
The comparison of risks associated with direct and indirect exposure
pathways for metals suggested that the direct pathways typically
present higher risks due to the: (1) weak uptake of soil-bound metals
in plants, (2) limited ability of metals to bioaccumulate on a wholebody
basis (with the exception of mercury; however levels of mercury in
HTMR slags, as presented in table 1, are not significant), and (3)
tendency of metals to remain bound in the slag matrix in a form that
further reduces their bioavailability.
Therefore, EPA evaluated four direct exposure pathways that were
identified as being relevant based on the presence of metal
contaminants in HTMR slags and the uses of the material. The four
direct exposure pathways of concern are:
<bullet> air pathway: emission and dispersion of respirable
particulates (<10 microns in size);
<bullet> groundwater pathway: release of contaminants to
subsurface soils and subsequent leaching into groundwater;
<bullet> surface water pathway: overland transport (via runoff and
soil erosion) of contaminants to surface water; and
<bullet> soil pathway: overland transport of contaminants via soil
erosion to offsite residential soils.

In addition to these direct exposure pathways, EPA identified one
indirect exposure pathway with respect to potential release scenarios,
i.e., release of nonrespirable particulates (30 microns in size)
followed by deposition to soil.

EPA did not model each of these four pathways for every source of
HTMR slags. The exposure pathways evaluated by EPA for each exposure
source/scenario are summarized in matrix form in Table 2. Only those
pathways relevant to a given source scenario were modeled for that
scenario. For example, as noted previously, direct air pathways for the
road subbase scenario were not evaluated because the subbase is
essentially a covered source that is not subject to wind erosion,
overland transport, or air dispersion. Similarly, EPA did not
explicitly include HTMR slags contained in cement or concrete/asphalt
mixtures for any of the exposure scenarios of concern.

Table 2.--Exposure Pathways Evaluated for Sources/Scenarios Associated With the Use or Disposal of HTMR Slag

Exposure source/scenario
---------------------------------------------------------------------------
Exposure pathway Top grade
Wastepile andanti-skid Slaglandfill Subbase Transportation

Ground Water Ingestion.............. X X X1 X
Surface Water....................... X X X
Soil Ingestion...................... X X X
Air Deposition to Soil and Ingestion X X X

Particulate Inhalation.............. X X X ............. X

1Evaluated previously (see 57 FR 37194; August 18, 1992)

5. Evaluation Criteria
EPA used human health and ecological (aquatic) effects criteria to
evaluate levels of hazardous constituents in various media.
a. Human Health--The human health reference values for the
constituents of concern includes carcinogenic slope factors (CSFs),
reference doses (RfDs), and reference concentrations (RfCs). The CSFs,
a measure of carcinogenic potency, were used for both the inhalation
and ingestion routes of exposure. The RfD is an estimate of the daily
intake of a substance, within an order of magnitude, to which the adult
human population (including sensitive subgroups) may be exposed without
any adverse noncarcinogenic effects. The RfC is the analog to the RfD
for inhalation exposure, although the RfC units are typically converted
to concentration (mg/m3), using default exposure assumptions for
breathing rate and body weight. Virtually all the reference values
(i.e., CSFs, RfDs, and RfCs) were obtained from the Integrated Risk
Information System (IRIS), EPA's primary source for verified human
health reference values. Reference values were also identified in the
Health Effects Assessment Summary Tables (HEAST). When no verified RfC
values were available, the RfC values were extrapolated from RfDs,
assuming that a 70 kg adult inhales 20 m3 of air per day. Based on
the human health reference values, the Agency calculated the reference
concentrations in Table 3 for soil, drinking water, and air. The table
includes Maximum Contaminant Levels (MCLs) for drinking water, when
available. The human health reference values, and the methods used to
calculate the reference concentrations, are summarized in the docket
for today's rule. Two constituents of concern, thallium and lead, did
not have reference values for ingestion or inhalation in either IRIS or
HEAST. The reference value (i.e., RfD) for thallium was estimated from
the lowest reference value of the thallium salts (e.g., thallium
sulfate, thallium nitrate). A reference value for lead is not available
at this time since Agency consensus has not been reached on how an RfD
or RfC should be calculated for lead. However, EPA has established
regulatory and recommended levels for lead in the various media, and
these are included in Table 3.
b. Ecological (Aquatic) Receptors--A comparison of chemical
concentrations in surface water to their aquatic benchmarks was used to
determine if any given constituent would pose a threat to aquatic
organisms. Those chemicals whose surface water concentrations exceeded
their aquatic water quality criteria would be identified as
constituents of concern. The National Ambient Water Quality Criteria
(NAWQC) were selected as the ecological reference concentrations for
the protection of aquatic organisms (e.g., fish and daphnids). Since
NAWQC were not available for all constituents, alternate criteria or
advisory values were identified in the open literature. A complete
description of the methods used to estimate the advisory NAWQC may be
found in Toxicological Benchmarks for Screening of Potential
Contaminants of Concern for Effects on Aquatic Biota on the Oak Ridge
Reservation, Oak Ridge, Tennessee (Suter et al., 1992). Table 3
provides the NAWQC and advisory NAWQC for aquatic organisms for each of
the constituents of concern.
6. Characterization of Risk
The modeling results for the ground-water, surface water, soil, and
air pathways were compared to the reference concentrations for the
different media to assess the potential risk to human health and
aquatic receptors. The resulting risk ratios (i.e., media concentration
divided by reference concentration) were then evaluated to determine
whether any of the metals of concern in HTMR slag would pose
significant risks to humans or aquatic receptors for any of the
exposure scenarios evaluated.

Table 3.--Reference Concentrations for Soil, Water, and Air for the HTMR Constituents of Concern

Reference Reference Surface
Reference Soil Drinking Water Reference Air Water

Constituent Concentration\1\ Concentrations\2\ Concentrations3 Concentrations\4\

(mg/kg) (mg/L) (ug/m\3\) (mg/

Antimony............................... 3.2E+01 0.006 1.4E+00 0.018
Arsenic................................ 9.7E-01 0.05 5.7E-04 0.190
Barium................................. 5.6E+03 2 5.0E-01 0.109
Beryllium.............................. 4.0E+02 0.004 1.0E-03 0.00061
Cadmium................................ 8.0E+01 0.005 1.4E-03 0.0011
Chromium III........................... 8.0E+04 0.1 3.5E+03 0.210
Chromium VI............................ 4.0E+02 0.1 2.0E-04 0.011
Lead................................... 4.0E+02 0.015 1.5E-01 0.0032
Mercury................................ 2.4E+01 0.002 3.0E-01 0.000012
Nickel................................. 1.6E+03 0.1 7.0E+01 0.160
Selenium............................... 4.0E+02 0.05 1.8E+01 0.035
Silver................................. 4.0E+02 0.18 1.8E+01 0.00039
Thallium............................... 6.4E+00 0.002 2.8E-01 0.0025
Zinc................................... 2.4E+04 10 1.1E+03 0.110

\1\RfDs and CSFs were used to calculate reference soil values, except for lead; the value for lead is a
recommended screening level for lead in soil for residential land use which is contained in the Agency's
interim soil lead guidance (this guidance suggests use of this screening level to identify sites that do not

require further study, and not as a clean up goal).

\2\Reference values for drinking water are MCLs, when available; the values for thallium and zinc are based on

RfDs, and the value for lead is the action level.

\3\Air reference values are based on CSFs or RfCs, when available; other values extrapolated from oral RfDs,
except for lead, which is based on 1012f the existing National Ambient Air Quality Standard.
\4\Reference values are National Ambient water Quality Criteria (NAWQC) for aquatic toxicity, except for
antimony, barium, beryllium, silver, and thallium, which are based on advisory NAWQC (see Section IV.A.5.b.)

B. Results of Risk Assessment

The results from EPA's very conservative risk assessment for the
relevant management practices and uses of HTMR slags indicate that
constituents of concern in HTMR slags pose little or no risk to human
health or the environment. Based on this assessment, no significant
risks were found for storage, transport, disposal, and encapsulated
uses of HTMR slags (use as subbase, as an ingredient in cement or
concrete/asphalt) that meet the generic exclusion levels. The nonencapsulated
uses of HTMR slags (top grade and anti-skid uses) that
meet the generic exclusion levels showed the potential for some excess
risk (i.e., risk above 1x10-6). The risk analysis indicates that
direct inhalation exposure to arsenic from non-encapsulated uses may
present an excess risk of cancer of 2.9x10-6. In other words, a
maximum of approximately 3 additional cases of cancer would be
predicted per million people exposed to the arsenic in the slag used in
this manner. The results also suggest that areal deposition of arsenic
from these non-encapsulated uses and subsequent ingestion of
contaminated soil may also present a comparable excess risk of cancer
(2.7x10-6). None of the other metals evaluated posed any
significant increase in risk for these uses.
These risks (from non-encapsulated uses) are at the low end of
EPA's risk range of 1x10-4 to 1x10-6. Furthermore, for this
assessment, EPA selected very conservative values for use in fate and
transport models and for exposure scenarios. If the risk assessment had
used a central tendency value (instead of a high-end value) for one of
the high-end exposure assumptions, then the calculated risks from these
uses would drop below the 1x10-6 level. For example, had the
Agency used a 9 year exposure period for an individual exposed instead
of the 30 year exposure period used in this risk calculation, the risk
from non-encapsulated uses would have dropped to 8.7x10-7 cancer
risk. This risk level is below the typical level of concern used by the
Agency.

C. Changes to the Generic Exclusion Levels

The generic exclusion levels promulgated for HTMR slags derived
from K061, K062, and F006 were based on the health-based levels and
MCLs in effect when the rule was put into place. Since then, the
drinking water standards (i.e., MCLs) for some constituents have
changed somewhat (see July 17, 1992, 57 FR 231776). Therefore, the
Agency is taking this opportunity to propose to update the exclusion
levels to reflect these changes. The original exclusion levels were
calculated by multiplying the MCLs by a dilution-attenuation factor of
10 (see August 18, 1992, 57 FR 37194). This factor is based on the
EPACML model (see July 18, 1991, 56 FR 32993 for a description of the
model used). Using this same factor, the new MCLs for antimony (0.006
mg/L) and beryllium (0.004 mg/L) would result in new generic exclusion
levels of 0.06 mg/L and 0.04 mg/L for antimony and beryllium,
respectively. Therefore, the Agency is proposing to replace the
existing exclusion levels in Sec. 261.3(c)(2)(ii)(C) for antimony and
beryllium with these values as part of today's rule. The Agency
promulgated an MCL for nickel in 1992. That regulatory standard was
challenged by a coalition of industry groups in a lawsuit filed in
September, 1992. See Nickel Development Institute et al. v. EPA, No.
92-1407, 1410, 1416 (D.C. Cir.). For the past two years, the Agency has
been involved in discussions with these industry parties in an effort
to resolve this litigation. Because of the uncertainties that currently
surround the outcome of this litigation over the nickel MCL, EPA
believes it is appropriate to consider alternative criteria to
establish the generic exclusion level for nickel. EPA considered using
the health-based level for nickel (0.7 mg/L) which is derived from the
existing RFD for nickel of 0.02 mg/kg/day (see IRIS). Based on the
calculations described in the above paragraph, this would result in a
generic exclusion level of 7 mg/L for nickel. The existing BDAT
treatment standard for nickel contained in the slags derived from HTMR
processing of K061, K062, and F006 wastes is 5 mg/L. Between these two
alternative criteria, EPA believes that it is appropriate to use the
lower (more conservative) BDAT standard at this time. Therefore, EPA is
proposing to replace the existing exclusion level in
Sec. 261.3(c)(2)(ii)(C) for nickel with the nickel BDAT treatment
standard of 5 mg/L.

V. Conclusions

Based on the results of the risk assessment, EPA is proposing that
HTMR slags that meet the generic exclusion levels in
Sec. 261.3(c)(2)(ii)(C) will be classified as nonhazardous waste, and
also allowed to be managed or used as described in this proposal.
Furthermore, the Agency is also proposing to amend Sec. 266.20 so
that all uses constituting disposal of hazardous HTMR slag (i.e., HTMR
slag that does not meet the generic exclusion levels) are no longer
exempt from RCRA Subtitle C regulation. Because it is highly unlikely
that users of hazardous HTMR slag will choose to meet the stringent
requirements of Subtitle C, this change would effectively prohibit all
uses of slags that do not meet the generic exclusion levels. As a
consequence of the proposed changes to the generic exclusion in
Sec. 261.3(c)(2)(ii)(C), HTMR slags that are used as described in this
proposal would not be affected by the changes in Sec. 266.20, because
the HTMR slags used in these ways would not be hazardous waste
(provided the slags meet the generic exclusion levels and all of the
other requirements specified in Sec. 261.3(c)(2)(ii)(C)).
Finally, as described in section IV.C above, the Agency is also
proposing to update the generic exclusion levels for changes in MCLs
for antimony, beryllium, and nickel.

VI. Effective Date

The Agency is proposing that this rule be effective six months
after the date of publication of the final rule. (See RCRA section
3010(a)). The Agency believes that this would provide sufficient time
for affected parties to comply with the proposed changes.

VII. State Authority

A. Applicability of Rule in Authorized States

Under section 3006 of RCRA, EPA may authorize qualified States to
administer and enforce the RCRA program within the State. Following
authorization, EPA retains enforcement authority under sections 3008,
3013, and 7003 of RCRA, although authorized States have primary
enforcement responsibility. The standards and requirements for
authorization are found in 40 CFR part 271.
Prior to the Hazardous and Solid Waste Amendments (HSWA) of 1984, a
State with final authorization administered its hazardous waste program
in lieu of EPA administering the Federal program in that State. The
Federal requirements no longer applied in the authorized State, and EPA
could not issue permits for any facilities that the State was
authorized to permit. When new, more stringent Federal requirements
were promulgated or enacted, the State was obliged to enact equivalent
authority within specified time frames. New Federal requirements did
not take effect in an authorized State until the State adopted the
requirements as State law.
In contrast, under RCRA section 3006(g), new requirements and
prohibitions imposed by HSWA take effect in authorized States at the
same time that they take effect in nonauthorized States. EPA is
directed to carry out these requirements and prohibitions in authorized
States, including the issuance of permits, until the State is granted
authorization to do so. While States must still adopt HSWA-related
provisions as State law to retain final authorization, HSWA applies in
authorized States in the interim.

B. Effect on State Authorization

EPA views today's proposed rule as a HSWA regulation. The proposed
rule can be viewed as part of the process of establishing land disposal
prohibitions and treatment standards for K061, K062, and F006 hazardous
wastes. (See 56 FR 41175). The ultimate goal of the land disposal
prohibition provisions is to establish standards which minimize shortterm
and long-term threats to human health and the environment posed by
hazardous waste land disposal. (See RCRA section 3004(m)(l)). In
addition, EPA must ensure that land disposal of hazardous wastes K061,
K062, and F006 are ultimately protective. (See RCRA Sec. 3004(g)(5)).
The proposed exclusion levels would implement these provisions by
assuring that these types of land disposal are ultimately protective
and establish levels at which pretreatment minimizes the threats to
human health and the environment posed by these types of land disposal.
Today's proposed rule will result in more stringent Federal
standards under Sec. 266.20, since it prohibits uses of hazardous HTMR
slags. Section 271.21(e)(2) requires that States that have final
authorization must modify their programs to reflect Federal program
changes and must subsequently submit the modifications to EPA for
approval.
Authorized States are only required to modify their programs when
EPA promulgates Federal regulations that are more stringent or broader
in scope than the existing Federal regulations. For those Federal
program changes that are less stringent or reduce the scope of the
Federal program, States are not required to modify their programs. This
is a result of section 3009 of RCRA, which allows States to impose
regulations in addition to those in the Federal program. EPA has
determined that the proposed changes to the generic exclusion are less
stringent or reduce the scope of the Federal program. Therefore,
authorized States are not required to modify their programs to adopt
regulations that are equivalent or substantially equivalent.
States with authorized RCRA programs may already have requirements
similar to those in today's proposed rule. These State regulations have
not been assessed against the Federal regulations being proposed today
to determine whether they meet the tests for authorization. Thus, a
State is not authorized to implement these requirements in lieu of EPA
until the State program modifications are approved. Of course, States
with existing standards could continue to administer and enforce their
standards as a matter of State law. In implementing the Federal
program, EPA will work with States under agreements to minimize
duplication of efforts. In many cases, EPA will be able to defer to the
States in their efforts to implement their programs rather than take
separate actions under Federal authority.

VIII. Regulatory Impact

A. Executive Order 12866

Under Executive Order 12866 (see 58 FR 51735, October 4, 1993), EPA
must determine whether the regulatory action is ``significant'' and
therefore subject to OMB review 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 affect 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 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 a ``significant regulatory action''
because it raises novel policy issues in terms of defining when
products used in a manner constituting disposal should be regulated. As
such, this action was submitted to OMB for review. Changes made in
response to OMB suggestions or recommendations will be documented in
the public record.

B. Regulatory Flexibility Act

Under the Regulatory Flexibility Act, 5 U.S.C. 601 et seq.,
whenever an Agency is required to issue a general notice of rulemaking
for any proposed or final rule, it must prepare and make available for
public comment a regulatory flexibility analysis that describes the
impact of the rule on small entities (i.e., small businesses, small
organizations, and small governmental jurisdictions). No regulatory
flexibility analysis is required, however, if the head of the Agency
certifies that the rule will not have any impact on any small entities.
This proposed rule will not have any impact on any small entities,
since the regulated community will continue to have readily available
options for using and managing HTMR slags. Therefore, pursuant to
section 605(b) of the Regulatory Flexibility Act, the Administrator
certifies that this regulation will not have a significant economic
impact on a substantial number of small entities. This regulation,
therefore, does not require a regulatory flexibility analysis.

C. Paperwork Reduction Act

The Agency has determined that there are no additional reporting,
notification, or recordkeeping provisions associated with this proposed
rule. Such provisions, were they included, would be submitted for
approval to OMB under the Paperwork Reduction Act, 44 U.S.C. 3501 et
seq.

List of Subjects

40 CFR Part 261

Environmental protection, Hazardous waste, Recycling, Reporting and
recordkeeping requirements.

40 CFR Part 266

Energy, Hazardous waste, Recycling, Reporting and recordkeeping
requirements.

40 CFR Part 268

Hazardous waste, Reporting and recordkeeping requirements.

Dated: December 16, 1994.
Carol M. Browner,
Administrator.
For the reasons set forth in the preamble, 40 CFR Chapter I is
amended as follows:

PART 261--IDENTIFICATION AND LISTING OF HAZARDOUS WASTE

The authority citation for part 261 continues to read as
follows:

Authority: 42 U.S.C. 6905, 6912(a), 6921, 6922, and 6938.

2. Section 261.3 paragraphs (c)(2)(ii)(C)(1) and (c)(2)(ii)(C)(2)
are revised as follows:

Sec. 261.3 Definition of hazardous waste.

(c) * * *
(2) * * *
(ii) * * *
(C)(1) Nonwastewater residues, such as slag, resulting from high
temperature metals recovery (HTMR) processing of K061, K062, and F006
waste, in units identified as rotary kilns, flame reactors, electric
furnaces, plasma arc furnaces, slag reactors, rotary hearth furnace/
electric furnace combinations or industrial furnaces (as defined in
paragraphs (6), (7), and (13) of the definition for ``Industrial
furnace'' in 40 CFR 260.10)--provided that these residues meet the
generic exclusion levels identified in the tables in this paragraph for
all constituents, and exhibit no characteristics of hazardous waste and
are disposed in Subtitle D units, or used as covered subbase materials
(e.g., in construction of paved roads, parking lots, and driveways) or
as additive ingredients in cement or concrete/asphalt mixtures, or as
top-grade (e.g., surfacing material for roads, parking lots, and
driveways), or as anti-skid/deicing materials. Testing requirements
must be incorporated in a facility's waste analysis plan or a
generator's self-implementing waste analysis plan; at a minimum,
composite samples of residues must be collected and analyzed quarterly
and/or when the process or operation generating the waste changes.
Persons claiming this exclusion in an enforcement action will have the
burden of proving by clear and convincing evidence that the material
meets all of the exclusion requirements.

Maximum for
any single
Constituent composite
sample-TCLP
(mg/l)

Generic exclusion level for K061 and K062

nonwastewater HTMR residues

Antimony.................................................. 0.06
Arsenic................................................... 0.50
Barium.................................................... 7.6
Beryllium................................................. 0.04
Cadmium................................................... 0.05
Chromium (total).......................................... 0.33
Lead...................................................... 0.15
Mercury................................................... 0.009
Nickel.................................................... 5
Selenium.................................................. 0.16
Silver.................................................... 0.30
Thallium.................................................. 0.02
Zinc...................................................... 70

Generic exclusion level for F006
nonwastewater HTMR residues

Antimony.................................................. 0.06
Arsenic................................................... 0.50
Barium.................................................... 7.6
Beryllium................................................. 0.04
Cadmium................................................... 0.05
Chromium (total).......................................... 0.33
Cyanide (total) (mg/kg)................................... 1.8
Lead...................................................... 0.15
Mercury................................................... 0.009
Nickel.................................................... 5
Selenium.................................................. 0.16
Silver.................................................... 0.30
Thallium.................................................. 0.02
Zinc...................................................... 70

(2) A one-time notification and certification must be placed in the
facility's files and sent to the EPA region or authorized state for
K061, K062, or F006 HTMR residues that meet the generic exclusion
levels for all constituents and do not exhibit any characteristics that
are sent to Subtitle D units, or used as described in paragraph
(c)(2)(ii)(C)(1). The notification and certification that is placed in
the generators or treaters files must be updated if the process or
operation generating the waste changes and/or if the subtitle D unit
receiving the waste changes. However, the generator or treater need
only notify the EPA region or an authorized state on an annual basis if
such changes occur. Such notification and certification should be sent
to the EPA region or authorized state by the end of the calendar year,
but no later than December 31. The notification must include the
following information: The name and address of the subtitle D unit
receiving the waste shipments; the EPA Hazardous Waste Number(s) and
treatability group(s) at the initial point of generation; and, the
treatment standards applicable to the waste at the initial point of
generation. The certification must be signed by an authorized
representative and must state as follows: ``I certify under penalty of
law that the generic exclusion levels for all constituents have been
met without impermissible dilution and that no characteristic of
hazardous waste is exhibited. I am aware that there are significant
penalties for submitting a false certification, including the
possibility of fine and imprisonment.

* * * *

PART 266--STANDARDS FOR THE MANAGEMENT OF SPECIFIC HAZARDOUS WASTES
AND SPECIFIC TYPES OF HAZARDOUS WASTE MANAGEMENT FACILITIES

3. The authority citation for part 266 continues to read as
follows:

Authority: 42 U.S.C. 6905, 6912(a), 6924, and 6934.

Subpart C--Recyclable Materials Used in a Manner Constituting
Disposal

4. Section 266.20 is amended by revising paragraph (c) to read as
follows:

Sec. 266.20 Applicability.

* * * *
(c) Slags, generated from high temperature metals recovery (HTMR)
processing of hazardous waste K061, K062, and F006, that are used in a
manner constituting disposal are not covered by the exemption in
paragraph (b) of this section and remain subject to regulation.
However, these slags are not hazardous wastes if they meet the
concentration levels as specified in Sec. 261.3(c)(2)(ii)(C) and are
used or disposed of as specified in Sec. 261.3(c)(2)(ii)(C).

PART 268--LAND DISPOSAL RESTRICTIONS

5. The authority citation for part 268 continues to read as
follows:

Authority: 42 U.S.C. 6905, 6912(a), 6921, and 6924.

6. Table ``Treatment Standards for Hazardous Wastes'' in
Sec. 268.40 is amended by adding a footnote ``8'' at the end of the
table and in the second column in the table,''Waste Description and
Treatment/Regulatory Subcategory'', for waste codes F006, K061, and
K062 to read as follows:

Sec. 268.40 Applicability of treatment standards.

\8\See also restrictions on use of slags in Sec. 261.3(c)(2)(ii)(C)
and Sec. 266.20(c).

[FR Doc. 94-31617 Filed 12-28-94; 8:45 am]
BILLING CODE 6560-50-P

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