[Federal Register Volume 64, Number 163 (Tuesday, August 24, 1999)]
[Proposed Rules]
[Pages 46166-46178]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-21941]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 261
[SW-FRL-6426-6]
Hazardous Waste Management System; Identification and Listing of
Hazardous Waste; Proposed Exclusion
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule and request for comment.
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SUMMARY: The EPA is proposing to grant a petition submitted by
Chaparral Steel Midlothian, L.P. (Chaparral) to exclude (or delist)
certain solid wastes generated by its Midlothian, Texas, facility from
the lists of hazardous wastes.
Any person may petition the Administrator to modify or revoke any
provision of the solid waste regulations. Generators are specifically
provided the opportunity to petition the Administrator to exclude a
waste on a ``generator specific'' basis from the hazardous waste lists.
The Agency bases its proposed decision to grant the petition on an
evaluation of waste-specific information provided by the petitioner.
This proposed decision, if finalized, would conditionally exclude the
petitioned waste from the requirements of hazardous waste regulations
under the Resource Conservation and Recovery Act (RCRA).
If finalized, we would conclude that Chaparral's petitioned waste
is nonhazardous with respect to the original listing criteria and that
the waste process Chaparral uses will substantially reduce the
likelihood of migration of hazardous constituents from this waste. We
would also conclude that their process minimizes short-term and long-
term threats from the petitioned waste to human health and the
environment.
DATES: We will accept comments until October 8, 1999. We will stamp
comments postmarked after the close of the comment period as ``late.''
These ``late'' comments may not be considered in formulating a final
decision.
ADDRESSES: Please send three copies of your comments. Two copies should
be sent to William Gallagher, Delisting Section, Multimedia Planning
and Permitting Division (6PD-O), Environmental Protection Agency, 1445
Ross Avenue, Dallas, Texas 75202. A third copy should be sent to the
Texas Natural Resources Conservation Commission (TNRCC), P.O. Box
13087, Austin, Texas, 78711-3087. Identify your comments at the top
with this regulatory docket number: ``F-99-TXDEL-CHAPARRAL.''
You should address requests for a hearing to the Acting Director,
Robert Hannesschlager, Multimedia Planning and Permitting Division
(6PD), Environmental Protection Agency, 1445 Ross Avenue, Dallas, Texas
75202.
Your requests for a hearing must reach EPA by September 8, 1999.
The request must contain the information prescribed in section
260.20(d).
FOR FURTHER INFORMATION CONTACT: William Gallagher at (214) 665-6775.
SUPPLEMENTARY INFORMATION:
The information in this section is organized as follows:
I. Overview Information
A. What action is EPA proposing?
B. Why is EPA proposing to approve this delisting?
C. How will Chaparral manage the waste if it is delisted?
D. When would the proposed exclusion be finalized?
E. How would this action affect states?
II. Background
A. What is the history of the delisting program?
B. What is a delisting petition, and what does it require of a
petitioner?
C. What factors must EPA consider in deciding whether to grant a
delisting petition?
III. EPA's Evaluation of the Waste Information and Data
A. What wastes did Chaparral petition EPA to delist?
B. What information and analysis did Chaparral submit to support
this petition?
C. Who is Chaparral and what process do they use to generate the
petition waste?
D. How did Chaparral sample and analyze the data in this
petition?
E. What were the results of Chaparral's analysis?
F. How did EPA evaluate the risk of delisting this waste?
G. What did EPA conclude about Chaparral's analysis?
H. What other factors did EPA consider in its evaluation?
I. What is EPA's final evaluation of this delisting petition?
IV. Next Steps
A. With what conditions must the petitioner comply?
B. What happens if Chaparral violates the terms and conditions?
V. Public Comments
A. How may I as an interested party submit comments?
B. How may I review the docket or obtain copies of the proposed
exclusions?
I. Overview Information
A. What Action is EPA Proposing?
The EPA is proposing:
(1) To grant Chaparral's petition to have their Landfill No. 3
leachate, baghouse storm water, and other
[[Page 46167]]
wastewater that may have been in contact with the K061 waste excluded,
or delisted, from the definition of a hazardous waste; and
(2) To use a fate and transport model to evaluate the potential
impact of the petitioned waste on human health and the environment. The
Agency uses this model to predict the concentration of hazardous
constituents released from the petitioned waste once it is disposed.
B. Why is EPA Proposing to Approve This Delisting?
Chaparral petitioned the Agency to exclude, or delist, the landfill
leachate, baghouse storm water, and other wastewaters that may have
potentially come in contact with K061 waste because they do not believe
that the petitioned waste meets the criteria for which EPA listed it.
Chaparral also believes no additional constituents or factors could
cause the wastes to be hazardous.
Based on our review, described below, EPA has determined that the
waste is nonhazardous with respect to the original listing criteria.
(If our review had found that the waste remained hazardous based on the
factors for which EPA listed the waste, we would have proposed to deny
the petition.)
In reviewing this petition, we considered the original listing
criteria and the additional factors required by RCRA section 3001(f),
42 U.S.C. 6921(f), and 40 CFR 260.22(d)(2)-(4). We evaluated the
petitioned waste against the listing criteria and factors cited in
Secs. 261.11(a)(2) and (a)(3).
We also evaluated the waste for other factors or criteria to assess
whether these additional factors could cause the waste to be hazardous.
These factors included: (1) whether the waste is considered acutely
toxic, (2) the toxicity of the constituents, (3) the concentration of
the constituents in the waste, (4) the waste constituent's tendency to
migrate and to bioaccumulate, (5) its persistence in the environment
once released from the waste, (6) plausible and specific types of
management of the petitioned waste, (7) the quantity of waste produced,
and (8) waste variability.
The EPA believes that the petitioned waste does not meet the
criteria for which it listed the waste and does meet the criteria for
delisting. The EPA's proposed decision to delist waste from Chaparral's
facility is based on the description of the proposed treatment system
and analytical data from the Midlothian facility submitted to support
today's rule.
C. How Will Chaparral Manage the Waste if it is Delisted?
The facility would like to manage the waste in their onsite cooling
system of which cooling ponds are a part. The wastewater would be
substituted for some of the well water presently used for cooling
purposes which would help conserve that natural resource. In this case,
the requested change in waste management is subject to delisting by EPA
and subsequent waste management practices in accordance with TNRCC
rules and regulations.
D. When Would the Proposed Delisting Exclusion be Finalized?
The Hazardous and Solid Waste Act specifically requires EPA to
provide notice and an opportunity for comment before granting or
denying a final exclusion. Thus, EPA will not grant the exclusion until
it addresses all timely public comments (including those at public
hearings, if any) on today's proposal.
This rule, if finalized, will become effective immediately upon
final publication. Section 3010(b) at 42 United States Code Annotated
6930(b) of RCRA allows rules to become effective in less than six
months when the regulated community does not need the six-month period
to come into compliance. That is the case here, because this rule, if
finalized, would reduce the existing requirements for persons
generating hazardous wastes.
The EPA believes that this exclusion should be effective
immediately upon final publication because a six-month deadline is not
necessary to achieve the purpose of section 3010(b), and a later
effective date would impose unnecessary hardship and expense on this
petitioner. These reasons also provide good cause for making this rule
effective immediately, upon final publication, under the Administrative
Procedure Act, 5 U.S.C. 553(d).
E. How would this action affect states?
Because EPA is issuing today's exclusion under the Federal RCRA
delisting program, only States subject to Federal RCRA delisting
provisions would be affected. This would exclude two categories of
States: States having a dual system that includes Federal RCRA
requirements and their own requirements, and States who have received
authorization from EPA to make their own delisting decisions.
Here are the details: We allow states to impose their own non-RCRA
regulatory requirements that are more stringent than EPA's, under
section 3009 of RCRA. These more stringent requirements may include a
provision that prohibits a federally issued exclusion from taking
effect in the State. Because a dual system (that is, both Federal
(RCRA) and State (non-RCRA) programs) may regulate a petitioner's
waste, we urge petitioners to contact the State regulatory authority to
establish the status of their wastes under the State law.
The EPA has also authorized some States (for example, Louisiana,
Georgia, Illinois) to administer a RCRA delisting program in place of
the Federal program, that is, to make State delisting decisions.
Therefore, this exclusion does not apply in those authorized States. If
Chaparral transports the petitioned waste to or manages the waste in
any State with delisting authorization, Chaparral must obtain delisting
authorization from that State before they can manage the waste as
nonhazardous in the State.
II. Background
A. What is the history of the delisting program?
The EPA published an amended list of hazardous wastes from
nonspecific and specific sources on January 16, 1981, as part of its
final and interim final regulations implementing section 3001 of RCRA.
The EPA has amended this list several times and published it in
Secs. 261.31 and 261.32.
We list these wastes as hazardous because: (1) they typically and
frequently exhibit one or more of the characteristics of hazardous
wastes identified in subpart C of part 261 (that is, ignitability,
corrosivity, reactivity, and toxicity) or (2) they meet the criteria
for listing contained in Secs. 261.11(a)(2) or (a)(3).
Individual waste streams may vary, however, depending on raw
materials, industrial processes, and other factors. Thus, while a waste
described in these regulations generally is hazardous, a specific waste
from an individual facility meeting the listing description may not be
hazardous.
For this reason, sections 260.20 and 260.22 provide an exclusion
procedure, called delisting, which allows persons to prove that EPA
should not regulate a specific waste from a particular generating
facility as a hazardous waste.
B. What is a delisting petition, and what does it require of a
petitioner?
A delisting petition is a request from a facility to EPA or an
authorized State to exclude wastes from the list of hazardous wastes.
The facility petitions the Agency because they do not consider the
wastes hazardous under RCRA regulations.
[[Page 46168]]
In a delisting petition, the petitioner must show that wastes
generated at a particular facility do not meet any of the criteria for
the listed wastes. The criteria for which EPA lists a waste are in part
261 and in the background documents for the listed wastes.
In addition, under section 260.22, a petitioner must prove that the
waste does not exhibit any of the hazardous waste characteristics (that
is, ignitability, reactivity, corrosivity, and toxicity) and present
sufficient information for EPA to decide whether factors other than
those for which the waste was listed warrant retaining it as a
hazardous waste. See part 261 and the background documents for the
listed wastes.
Generators remain obligated under RCRA to confirm whether their
waste remains nonhazardous based on the hazardous waste characteristics
even if EPA has ``delisted'' the wastes.
C. What factors must EPA consider in deciding whether to grant a
delisting petition?
Besides considering the criteria in section 260.22(a), in 42 U.S.C.
6921(f), and in the background documents for the listed wastes, EPA
must consider any factors (including additional constituents) other
than those for which we listed the waste if a reasonable basis exists
that these additional factors could cause the waste to be hazardous.
See 3010(b) of the Solid Waste Disposal Act.
The EPA must also consider as hazardous wastes mixtures containing
listed hazardous wastes and wastes derived from treating, storing, or
disposing of listed hazardous waste. See Secs. 261.3(a)(2)(iii and iv)
and (c)(2)(i), called the ``mixture'' and ``derived-from'' rules,
respectively. These wastes are also eligible for exclusion and remain
hazardous wastes until excluded.
The ``mixture'' and ``derived-from'' rules are now final, after
having been vacated, remanded, and reinstated. On December 6, 1991, the
U.S. Court of Appeals for the District of Columbia vacated the
``mixture/derived from'' rules and remanded them to EPA on procedural
grounds. See Shell Oil Co. v. EPA., 950 F.2d 741 (D.C. Cir. 1991). On
March 3, 1992, EPA reinstated the mixture and derived-from rules, and
solicited comments on other ways to regulate waste mixtures and
residues. See (57 FR 7628) These rules became final on October 30,
1992. See (57 FR 49278) Consult these references for more information
about mixtures derived from wastes.
III. EPA's Evaluation of the Waste Information and Data
A. What wastes did Chaparral petition EPA to delist?
On February 23, 1999, Chaparral Steel petitioned EPA for a
conditional exclusion for 500,000 gallons (about 2,500 cubic yards) per
year of leachate from its Landfill No. 3 single RCRA landfill unit
containing electric arc furnace dust. The furnace dust is captured in
the baghouse during the steelmaking process and is a listed hazardous
waste classified as K061. The petitioned wastes are largely leachate
generated in the landfill's leachate collection system and minor
amounts of K061 wastewater from various plant operations including
storm water from the baghouse floor areas and the pelletizer sump.
These liquid wastes are presently pumped to an onsite storage tank. The
resulting waste is also listed under Sec. 261.3(c)(2)(i) (the ``derived
from'' rule), as EPA Hazardous Waste No. K061. The listed constituents
of concern for this waste code are hexavalent chromium, lead, and
cadmium.
B. What information and analysis did Chaparral submit to support this
petition?
To support its petition, Chaparral submitted:
(1) historical analytical data for the Electric Arc Furnace Dust
(K061), and leachate analytical data from their Landfill No. 3
containing the Electric Arc Furnace Dust, and analytical data for the
liquid from the K061 waste water storage tank;
(2) analytical results of the total constituent list for 40 CFR
part 264, appendix IX volatiles, semivolatiles, metals (including
hexavalent chromium), pesticides, herbicides, polychlorinated
biphenyls, furans, and dioxins;
(3) analytical results of the constituent list derived from
appendix IX for identified constituents;
(4) analytical results for reactive sulfide;
(5) analytical results for reactive cyanide;
(6) test results for corrosivity by pH;
(7) analytical results of samples from bench tests of treated
leachate/K061 wastewater; and
(8) test results for oil and grease.
C. Who is Chaparral and what process do they use to generate the
petitioned waste?
Chaparral Steel operates a steel plant which manufactures primary
steel from scrap steel utilizing an electric arc furnace process with
continuous casting of billets, and then rolling to finished goods.
Electric arc furnace dust, which is captured in the baghouse during the
steelmaking process, is a listed hazardous waste (K061). In the past,
K061 was landfilled on-site. The on-site landfills have been closed.
The baghouse K061 wastes are currently shipped off-site for metals
recovery or are reused on site by reintroduction to the electric arc
furnace.
Leachate from Landfill No. 3 which also bears the K061 waste
classification, is collected from the landfill's leachate collection
system and stored in an on-site tank. Small amounts of water from
various locations within the facility including storm water from the
palletizer sump and storm water from the baghouse floor (which is
potentially mixed with electric arc furnace dust and therefore would
also be designated as K061) is also placed in the tank occasionally.
Also minor amounts of water that has potentially contacted K061 is
occasionally added to the tank. However, the amounts of storm water and
other potentially contaminated wastewaters are very minor as compared
to the leachate. The contents of the leachate tank are presently
transported to an offsite injection facility for disposal.
D. How did Chaparral sample and analyze the data in this petition?
Chaparral developed a list of constituents of concern from prior
analytical data and by analyzing the first sample for the entire
appendix IX list of hazardous constituents found in 40 CFR part 264.
More specifically, Chaparral analyzed one treated and one raw leachate
composite sample for the total concentrations (i.e., mass of a
particular constituent per mass of waste) of the volatiles and
semivolatiles, metals, herbicides, pesticides, PCBs, and furans from
appendix IX. These two samples were analyzed for the comprehensive list
in order to confirm that there were no other constituents of concern in
the petitioned waste.
Chaparral collected four composite samples from the storage tank
over a twenty-five week period. They collected these samples in this
manner to ensure that the samples represented the potential time and
space variability of the petitioned waste. All samples were analyzed
for constituents of concern and were also analyzed to determine whether
the waste exhibited ignitable, corrosive, or reactive properties as
defined under 40 CFR 261.21, 261.22, and 261.23, including analysis for
reactive constituent concentrations of cyanide and sulfide. These
samples were not analyzed for TCLP
[[Page 46169]]
concentrations (i.e., mass of a particular constituent per unit volume
of extract) since the leachate is a liquid and the total analysis
concentration is considered to be the TCLP concentration.
------------------------------------------------------------------------
Chaparral used these methods To quantify
------------------------------------------------------------------------
SW-846 Method 8260, and 8270.............. The total constituent
concentrations of 40 CFR,
part Sec. 264 Appendix IX
Volatiles and Appendix IX
Semivolatiles including
PCBs, Pesticides, and
Herbicides.
SW-846 Methods 6010, 7041, and 7740, and Appendix IX Metals.
7196.
SW-846 Methods 7470....................... Mercury.
9071...................................... Total oil and grease.
9045...................................... pH
9030...................................... Reactive Sulfide.
9010...................................... Reactive Cyanide.
1010...................................... Ignitability.
------------------------------------------------------------------------
E. What were the results of Chaparral's analysis?
Tables 1 and 2 present the maximum total constituent leachate
concentrations for the raw waste and for the treated waste samples from
bench test studies. The bench test study simulated a typical wastewater
treatment process. If the raw (untreated) waste does not meet delisting
criteria, then Chaparral intends to treat the waste in a wastewater
treatment plant to meet the delisting criteria.
The wastewater treatment process would add a coagulant such as
ferric chloride to precipitate the metal constituents and then add a
cationic polymer to flocculate the metal constituents. A filter unit
would remove the precipitated metal constituents which would yield a
wastewater with concentrations of constituents of concern well below
the delisting criteria concentrations.
Chaparral calculated, based on historical information and the worst
case scenario, the maximum petitioned waste to be excluded on a yearly
basis will be 500,000 gallons (or about 2500 cubic yards) of petitioned
waste. The sworn affidavit submitted with this petition binds the
petitioner to present truthful and accurate results. The EPA reviews a
petitioner's estimates and, on occasion, has requested a petitioner to
reevaluate the estimated waste volume. The EPA accepted Chaparrals'
certified estimates. The EPA does not generally verify submitted test
data before proposing delisting decisions. The EPA, however, has
maintained a spot-check sampling and analysis program to verify the
representative nature of the data for some percentage of the submitted
petitions. A spot-check visit to a selected facility may be initiated
before finalizing a delisting petition or after granting an exclusion.
Table 1.--Maximum Organic Total Constituent Concentrations 1 For Raw
Leachate/K061 Wastewater and Treated Leachate/K061 Wastewater from the
Storage Tank
------------------------------------------------------------------------
Total
Total Constituent
Constituent Analyses for
Constituents Analyses for Treated
Raw Leachate 1 Leachate 1 (mg/
(mg/l) l)
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1,2-Dichloroethane.................... 0.004 <0.005
2-Butanone............................ 0.003 0.005
4-Methyl-2-pentanone.................. 0.008 0.005
Acetone............................... 0.08 0.1
Carbon Disulfide...................... 0.003 0.005
Chloromethane......................... <0.01 0.001
Ethylbenzene.......................... 0.004 <0.005
Methyl Iodide......................... <0.01 0.002
Methylene Chloride.................... 0.001 <0.005
Toluene............................... 0.001 0.004
Xylene................................ 0.03 0.006
------------------------------------------------------------------------
< Denotes that the constituent was not detected at the detection limit
specified in the table.
\1\ These levels represent the highest concentration of each constituent
found in any one sample. These levels do not necessarily represent the
specific levels found in one sample.
F. How did EPA evaluate the risk of delisting this waste?
Chaparral Steel's petition requests a conditional delisting for
listed hazardous wastes. In making the initial delisting determination,
EPA evaluated the petitioned wastes against the listing criteria and
factors cited in Secs. 261.11(a)(1), 261.11(a)(2) and 261.11(a)(3).
Based on this review, EPA has determined that the waste is nonhazardous
with respect to the original listing criteria. (If EPA had found, based
on this review, that the wastes remained hazardous based on the factors
for which the wastes were originally listed, EPA would have proposed to
deny the petition.) The EPA then evaluated the wastes with respect to
other factors or criteria to assess whether there is a reasonable basis
to believe that such additional factors could cause the wastes to be
hazardous. The EPA considered whether the wastes are acutely toxic, the
toxicity of the constituents, the concentration of the constituents in
the wastes, their tendency to migrate and to bioaccumulate, their
persistence in the environment once released from the wastes, plausible
and specific types of management of the petitioned wastes, the
quantities of wastes generated, and waste variability.
For this delisting determination, EPA used such information
gathered to identify plausible exposure routes (i.e., ground water,
surface water and air) for hazardous constituents present in the
petitioned wastes. The EPA determined that disposal in a surface
impoundment is the most reasonable, worst-case disposal scenario for
Chaparral's petitioned wastes, and that the major exposure route of
concern would be ingestion of contaminated ground water. Therefore, EPA
used a particular fate and transport model, EPA Composite Model for
Landfills (EPACML), to predict the maximum allowable concentrations of
hazardous
[[Page 46170]]
constituents that may be released from the petitioned wastes after
disposal and to determine the potential impact of the disposal of
Chaparral's petitioned wastes on human health and the environment. You
can find a detailed description of the EPACML model, the disposal
assumptions, and the modifications made for delisting in 56 FR 32993
(July 18, 1991), 56 FR 67197 (December 30, 1991) and the RCRA public
docket. This model includes both unsaturated and saturated zone
transport modules. It uses the reasonable worse-case contaminant levels
in ground water at a compliance point (that is, a receptor well serving
as a drinking-water supply.)
Specifically, EPA used the maximum estimated waste volumes and the
maximum reported concentrations as inputs to estimate the constituent
concentrations in the ground water at a hypothetical receptor well
downgradient from a theoretical disposal site. The calculated receptor
well concentrations (referred to as compliance-point concentrations)
were then compared directly to the current Maximum Contaminant Levels
(MCLs) promulgated under the Safe Drinking Water Act or health-based
levels derived from verified Reference Doses. The values used for lead
and copper are action levels for treatment of a water supply in lieu of
an MCL (40 CFR 141.80).
The EPA believes that this fate and transport model represents a
reasonable worst-case scenario for disposal of the petitioned wastes in
a surface impoundment, and that a reasonable worst-case scenario is
appropriate when evaluating whether a waste should be relieved of the
protective management constraints of RCRA subtitle C. The use of a
reasonable worst-case scenario results in conservative values for the
compliance-point concentrations and gives a high degree of confidence
that the waste, once removed from hazardous waste regulation, will not
pose a threat to human health or the environment. In most cases,
because a delisted waste is no longer subject to hazardous waste
control (unless conditionally delisted), EPA is generally unable to
predict, and does not presently control, how a waste will be managed
after delisting. Therefore, EPA normally believes that it is
inappropriate to consider extensive site-specific factors when applying
the fate and transport model. If however, conditions contained in a
delisting indicate that it is necessary to consider site specific
factors or otherwise indicate that the model is inappropriate, EPA may
consider these factors in applying the model.
The EPA also considers the applicability of ground water monitoring
data during the evaluation of delisting petitions. The evaluation of
the information submitted indicated that the waste is managed in a tank
with secondary containment. Therefore ground water data is not
applicable to this petition.
From the evaluation of Chaparral's delisting petition, one of the
constituents evaluated, lead, is being proposed as a verification
testing condition. Proposed maximum allowable leachable concentrations
for this constituent was derived by back-calculating from the delisting
health-based levels through the proposed fate and transport model for a
surface impoundment management scenario and by comparing results with
the Land Disposal Restrictions (LDRs) maximum allowable concentration.
The lowest of these two concentrations (i.e., delisting levels) are
part of the verification testing conditions of the proposed exclusion.
Therefore, delisting levels are less than LDR concentrations and thus
the LDRs are met. Details of the evaluation of lead and other
constituents of concern is explained in more detail later in this
section.
Chaparral's exclusion (if granted) would be contingent upon the
facility conducting sampling and analysis of the waste to insure that
the delisting conditions are met (i.e., wastes meet EPA's verification
testing conditions).
The EPA's proposed decision is based on the information submitted
in support of today's rule, i.e., historical data from the Landfill No.
3 leachate, analytical data from recent samples from the leachate
storage tank containing leachate and K061 wastewaters, and analytical
data from bench tests of the leachate/K061 wastewaters after treatment
in a simulated wastewater treatment system.
Finally, RCRA (7004(b)(1)) specifically requires EPA to provide
notice and an opportunity for comment before granting or denying a
final exclusion. Thus, a final decision will not be made until all
timely public comments (including those at public hearings, if any) on
today's proposal are addressed.
The EPA's evaluation of the raw leachate using a Dilution
Attenuation Factor of 68, a maximum waste volume annually of 2500 cubic
yards (or 500,000 gallons per calender year), and the maximum reported
constituent concentrations (see Tables 1 and 2), yielded compliance
point concentrations (see Tables 3 and 4) that are below the current
health-based levels except for the constituent lead which is discussed
below.
In Table 3, the calculated compliance point concentrations derived
from the maximum reported leachate concentrations (see Table 1) of the
organic constituents detected in the waste are compared with the levels
of concern. The organic constituents are believed to be artifacts from
sampling or analysis errors because: (1) the arc furnace process should
have destroyed the organic chemicals, (2) the organic constituents are
not detected consistently, (3) most detections are near the detection
limits, and (4) several of the compounds are common laboratory
contaminants. However, in spite of this reasoning, EPA completed the
evaluation conservatively using the highest concentration found for
each organic constituent in the petitioned waste. As shown in Table 3,
the maximum reported leachate concentrations of 1,2-dichloroethane, 2-
butanone, 4-methyl-2-pentanone, acetone, carbon disulfide,
ethylbenzene, methylene chloride, toluene, and xylene yielded
compliance point concentrations below the health-based levels used in
delisting decision-making. It should also be noted that the
concentrations of the organic constituents found in the raw leachate
are below LDR concentration values and therefore the LDRs are met. See
Table 1.
The EPA also evaluated the mobility of the two remaining organic
constituents cloromethane and methyl iodide which were not detected in
the leachate but were found in the treated leachate at concentrations
of 0.001 and 0.002 mg/l yielding compliance concentrations of 0.00001
and 0.00003 mg/l, in respective order. These concentrations are well
below the levels of concern of 0.007 and 0.03 mg/l, respectively. The
0.001 and 0.002 mg/l values are below the LDR concentration values and
therefore the LDRs are met.
In Table 4, the calculated compliance point concentrations derived
from the maximum reported leachate/K061 wastewater concentrations of
the inorganic constituents (see Table 2) detected in the petitioned raw
waste are compared with the levels of regulatory concern. The maximum
reported or calculated concentrations of arsenic, barium, cadmium,
total chromium, copper, mercury, nickel, vanadium, and zinc yielded
compliance point concentrations below Levels of Concern.
The EPA did not evaluate the mobility of the constituents
beryllium, hexavalent chromium, cobalt, selenium, silver, thallium and
cyanide from Chaparral's petitioned waste because
[[Page 46171]]
these constituents were not detected in the leachate using the
appropriate analytical test methods. See Table 2. The EPA believes that
it is inappropriate to evaluate nondetectable concentrations of a
constituent of concern in its delisting modeling efforts if the
nondetectable value was obtained using the appropriate analytical
method. If a constituent cannot be detected (when using the appropriate
analytical method with an adequate detection limit), EPA, for delisting
purposes, assumes that the constituent is not present and therefore
does not present a threat to human health or the environment. In the
delisting program EPA believes it is inappropriate to evaluate
constituents undetected in the waste samples.
The maximum reported raw leachate concentration for a single sample
of lead (2.0 mg/l) yielded a calculated compliance point concentration
(0.029 mg/l) slightly above the health-based level (0.015 mg/l) used in
the delisting decision-making process.
The lead value (0.029 mg/l) represents the calculated leachate
concentrations of lead at a theoretical downgradient ground water
monitoring well using the EPACML model and a concentration value of 2.0
mg/l from one raw waste sample. This value was the highest
concentration identified for the four analysis completed for lead. The
four concentration values for lead as identified in the raw waste were
2.0, 1.3, 0.5 and 0.55 mg/l and the values for the treated waste were
0.081, 0.06, 0.026, and <0.0011 mg/l. Two of the raw waste lead values
(0.5 and 0.55 mg/l) and all of the treated samples yield calculated
compliance point concentrations below the concentration of concern. For
this reason, verification testing for one waste constituent, lead, will
be a condition of the delisting.
Lead was the only constituent that did not consistently have
calculated compliance point concentrations below the concentrations of
concern. As shown in Tables 3 and 4, all other constituents were always
below the concentrations of concern at the calculated compliance point.
It should also be noted that the concentration values as measured in
the raw waste for all other constituents of concern were below the LDR
concentration values. Therefore, with the exception of the constituent
lead, the petitioned waste meets LDR concentration values even before
the compliance point concentrations are calculated. Seven years of
historical leachate data also supported the decision that lead was the
only Constituent of Concern which should require verification testing.
Table 2.--Maximum Inorganic Total Constituent Concentrations For Raw
Leachate/K061 Wastewater and Treated Leachate/K061 Wastewater From the
K061 Storage Tank
------------------------------------------------------------------------
Total
Total Constituent
Constituent Analyses for
Constituents Analyses for Treated
Raw Leachate Leachate \1\
\1\ (mg/l) (mg/l)
------------------------------------------------------------------------
Antimony.............................. <0.0066 0.008
Arsenic............................... 0.081 0.068
Barium............................... 0.26 0.007
Beryllium............................. <0.0017 <0.0017
Cadmium............................... 0.019 0.0020
Chromium (Total)...................... 0.17 0.013
Chromium (Hexavalent)................. <0.1 <0.02
Cobalt................................ <0.0016 <0.0016
Copper................................ 0.096 0.029
Lead.................................. 2 0.081
Mercury............................... 0.00031 0.00016
Nickel................................ 0.019 0.014
Selenium.............................. <0.01 0.044
Silver................................ <0.0012 <0.0012
Thallium.............................. <0.0096 <0.0096
Tin................................... 0.025 0.017
Vanadium.............................. 0.042 0.038
Zinc.................................. 5.6 0.08
Sulfide (Total)....................... 1.3 <1.0
Cyanide (Total)....................... <0.0018 <0.0018
------------------------------------------------------------------------
< Denotes that the constituent was not detected at the noted detection
limit.
\1\ These levels represent the highest concentration of each constituent
found in any one sample. These levels do not necessarily represent the
specific levels found in one sample.
Table 3.--EPACML: Calculated Compliance Point Organic Concentrations for
Raw Leachate and K061 Wastewater From the K061 Storage Tank.
------------------------------------------------------------------------
Compliance Point Levels of
Organic Constituents Concentrations Concern \2\ (mg/
\1\ (mg/l) l)
------------------------------------------------------------------------
1,2-Dichloroethane.................. 0.00006 0.005
2-Butanone.......................... 0.00004 20.
4-Methyl-2-pentanone................ 0.0001 2.
Acetone............................. 0.001 4.
Carbon Disulfide.................... 0.00004 4.
Ethylbenzene........................ 0.00006 70.
Methylene Chloride.................. 0.00001 0.005
Toluene............................. 0.00001 1.
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Xylene.............................. 0.0004 10.
------------------------------------------------------------------------