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[Federal Register Volume 65, Number 188 (Wednesday, September 27, 2000)]
[Proposed Rules]
[Pages 58015-58031]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-24790]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 261

[SW-FRL-6878-3]

Hazardous Waste Management System; Proposed Exclusion for 
Identification and Listing Hazardous Waste

AGENCY: Environmental Protection Agency, (EPA).

ACTION: Proposed rule and request for comment.

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SUMMARY: The EPA (also, ``the Agency'' or ``we'' in this preamble) is 
proposing to grant a petition submitted by USG Corporation (USG), 
Chicago, Illinois, to exclude (or ``delist''), on a one-time basis, 
certain solid wastes that are interred at an on-site landfill at its 
American Metals Corporation (AMC) facility in Westlake, Ohio from the 
lists of hazardous wastes contained in Subpart D of 40 Code of Federal 
Regulations (CFR) Part 261. This landfill was used exclusively by Donn 
Corporation, the original site owner, for disposal of its wastewater 
treatment plant (WWTP) sludge from 1968 to 1978.
    USG submitted the petition under 40 CFR 260.20 and 260.22(a). 
Section 260.20 allows any person to petition the Administrator to 
modify or revoke any provision of parts 260 through 266, 268 and 273. 
Section 260.22(a) specifically provides a generator the opportunity to 
petition the Administrator to exclude a waste on a ``generator 
specific'' basis from the hazardous waste lists.
    The Agency has tentatively decided to grant the petition based on 
an evaluation of waste-specific information provided by USG. This 
proposed decision, if finalized, conditionally excludes the petitioned 
waste from the requirements of hazardous waste regulations under the 
Resource Conservation and Recovery Act (RCRA).
    We conclude that USG's petitioned waste is nonhazardous with 
respect to the original listing criteria or factors which could cause 
the waste to be hazardous.

DATES: Comments. We will accept public comments on this proposed 
decision until November 13, 2000. 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.
    Request for Public Hearing. Your request for a hearing must reach 
EPA by October 12, 2000. The request must contain the information 
prescribed in Sec. 260.20(d).

ADDRESSES: Comments. Please send two copies of your comments to Todd 
Ramaly, Waste Management Branch (DW-8J), Environmental Protection 
Agency, 77 W. Jackson Blvd., Chicago, IL 60604.
    Request for Public Hearing. Any person may request a hearing on 
this proposed decision by filing a request with Robert Springer, 
Director, Waste, Pesticides and Toxics Division, Environmental 
Protection Agency, 77 W. Jackson Blvd., Chicago, IL 60604.

FOR FURTHER INFORMATION CONTACT: For technical information concerning 
this document, contact Todd Ramaly at the address above or at 312-353-
9317. The RCRA regulatory docket for this proposed rule is located at 
the EPA Region 5, 77 W. Jackson Blvd., Chicago, IL 60604, and is 
available for viewing from 8:00 a.m. to 4:00 p.m., Monday through 
Friday, excluding federal holidays. Call Todd Ramaly at (312) 353-9317 
for appointments. The public may copy material from the regulatory 
docket at $0.15 per page.

SUPPLEMENTARY INFORMATION:
I. Overview Information
    A. What action is EPA proposing?
    B. Why is EPA proposing to approve this delisting?
    C. How will USG manage the waste if it is delisted?
    D. When would EPA finalize the proposed delisting exclusion?
    E. How would this action affect the states?
II. Background
    A. What is the history of the delisting program?

[[Page 58016]]

    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 USG petition EPA to delist?
    B. What information and analyses did USG submit to support this 
petition?
    C. How did USG generate the petitioned waste?
    D. How did USG sample and analyze the data in this petition?
    E. What were the results of USG's analysis?
IV. Methodology for Risk Assessments
    A. How did EPA evaluate the risk of delisting this waste?
    B. What risk assessment methods has the Agency used in previous 
delisting determinations?
V. Evaluation of This Petition
    A. What other factors did EPA consider in its evaluation?
    B. What did EPA conclude about USG's analysis?
    C. What is EPA's final evaluation of this delisting petition?
VI. Conditions for Exclusion
    A. What are the maximum allowable concentrations of hazardous 
constituents in the waste?
    B. What are the conditions of the exclusion?
    C. What happens if USG fails to meet the conditions of the 
exclusion?
VII. Regulatory Impact
VIII. Regulatory Flexibility Act
IX. Paperwork Reduction Act
X. Unfunded Mandates Reform Act
XI. Executive Order 12875
XII. Executive Order 13045
XIII. Executive Order 13084
XIV. National Technology Transfer and Advancement Act

I. Overview Information

A. What Action Is EPA Proposing?

    The EPA is proposing to grant USG's petition to have its wastewater 
treatment sludge excluded, or delisted, from the definition of a 
hazardous waste. We evaluated the petition using a fate and transport 
model to predict the concentration of hazardous constituents which 
could be released from the petitioned waste after it is disposed.

B. Why Is EPA Proposing To Approve This Delisting?

    USG petitioned EPA to exclude, or delist, the wastewater treatment 
sludge because USG believes that the petitioned waste does not meet the 
criteria for which EPA listed it. USG also believes there are no 
additional constituents or factors which could cause the wastes to be 
hazardous. Based on our review described below, we agree with the 
petitioner that the waste is nonhazardous.
    In reviewing this petition, we considered the original listing 
criteria and the additional factors as required by the Hazardous and 
Solid Waste Amendments of 1984 (HSWA). See 222 of HSWA, 42 U.S.C. 
6921(f), and 40 CFR 260.22 (d)(2) through (4). We evaluated the 
petitioned waste against the listing criteria and factors cited in 
Sec. 261.11(a)(2) and (3) and in the background documents.
    We also evaluated the waste for other factors including (1) the 
toxicity of the constituents; (2) the concentration of the constituents 
in the waste; (3) the tendency of the hazardous constituents to migrate 
and to bioaccumulate; (4) persistence in the environment of any 
constituents released from the waste; (5) plausible and specific types 
of management of the petitioned waste; (6) the quantity of waste 
produced; and (7) waste variability.
    We believe that the petitioned waste does not meet the criteria for 
which the waste was listed, and have tentatively decided to delist 
waste from the AMC Westlake landfill.

C. How Will USG Manage the Waste If It Is Delisted?

    If the petitioned waste is delisted, USG must dispose of it in a 
Subtitle D landfill which is permitted, licensed, or registered by a 
state to manage industrial waste. This exclusion does not change the 
regulatory status of the landfill in Westlake, Ohio where the waste has 
been disposed.

D. When Would EPA Finalize the Proposed Delisting Exclusion?

    HSWA specifically requires the EPA to provide notice and an 
opportunity for comment before granting or denying a final exclusion. 
Thus, EPA will not make a final decision or grant an exclusion until it 
has addressed all timely public comments (including those at public 
hearings, if any) on today's proposal.
    Since this rule would reduce the existing requirements for persons 
generating hazardous wastes, the regulated community does not need a 
six-month period to come into compliance in accordance with section 
3010 of RCRA as amended by HSWA. Therefore, the exclusion would become 
effective upon finalization.

E. How Would This Action Affect the 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 exclusion may not be effective in 
states having a dual system that includes federal RCRA requirements and 
their own requirements, or in states which have received our 
authorization to make their own delisting decisions.
    Under section 3009 of RCRA, EPA allows states to impose their own 
non-RCRA regulatory requirements that are more stringent than EPA's. 
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.
    EPA has also authorized some states to administer a 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 USG transports the petitioned waste to or manages 
the waste in any state with delisting authorization, USG must obtain a 
delisting from that state before it 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 40 CFR 
261.31 and 261.32.
    We list 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 Sec. 261.11(a)(2) or (3).
    Individual waste streams may vary 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.
    For this reason, 40 CFR 260.20 and 260.22 provide an exclusion 
procedure, called delisting, which allows a person to demonstrate that 
EPA should not regulate a specific waste from a particular generating 
facility as a hazardous waste.

[[Page 58017]]

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 waste generated at a particular facility 
from the list of hazardous wastes.
    In a delisting petition, the petitioner must show that wastes 
generated does not meet any of the criteria for listed wastes and does 
not exhibit any of the hazardous waste characteristics in 40 CFR Part 
261, Subpart C. The criteria for which EPA lists a waste are in 40 CFR 
261.11 and in the background documents. The petitioner must also 
present sufficient information to determine whether factors other than 
those for which the waste was listed warrant retaining it as a 
hazardous waste. (See Sec. 260.22, 42 U.S.C. 6921(f) and the background 
documents for the listed wastes.)
    A generator remains obligated under RCRA to confirm that its 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?

    EPA must also consider as a hazardous waste, a mixture containing 
listed hazardous wastes and wastes derived from treating, storing, or 
disposing of a listed hazardous waste. See 40 CFR 261.3(a)(2)(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.

III. EPA's Evaluation of the Waste Information and Data

A. What Wastes Did USG Petition EPA To Delist?

    On May 22, 1997, USG petitioned EPA to exclude the estimated total 
landfill volume of the WWTP sludge (estimated at 12,400 cubic yards) 
from the list of hazardous wastes contained in 40 CFR 261.31 in order 
to facilitate ongoing corrective action at the AMC site. The WWTP 
sludge is described in USG's petition as a mixture of (1) EPA Hazardous 
Waste Number F019 wastewater treatment sludge that was generated from 
the chemical coating of aluminum, (2) other nonhazardous wastewater 
treatment sludges derived from the chemical coating of steel and 
galvanized steel, and (3) various nonhazardous solid wastes. F019 is 
defined as ``Wastewater treatment sludges from the chemical conversion 
coating of aluminum except from zirconium phosphating in aluminum can 
washing when such phosphating is an exclusive conversion coating 
process.'' The constituents of concern for which F019 is listed are 
hexavalent chromium and complexed cyanide.

B. What Information and Analyses Did USG Submit To Support This 
Petition?

    To support its petition, USG submitted (1) descriptions and 
schematic diagrams of its manufacturing and wastewater treatment 
processes, including historical information on past waste generation 
and management practices; (2) detailed chemical and physical analysis 
of the landfilled sludge (see Section III.D.); and (3) environmental 
monitoring data from recent studies of the facility, including 
groundwater data from wells located in and around the on-site landfill.

C. How Did USG Generate the Petitioned Waste?

    AMC began generating wastewater treatment sludge in 1965 with the 
start of its metal coil coating line. After 1967, AMC cleaned, 
chemically coated, painted, and slit large coils of steel, galvanized 
steel, and aluminum, into metal strips that were fabricated into the 
structural components for suspended ceiling panels. Wastewater from the 
coil coating line contained dissolved metals and vegetable oils that 
were treated in the AMC WWTP. As part of the wastewater treatment 
process, oils were removed in an oil/water separator and metals were 
precipitated in a ``lime'' sludge. The AMC wastewater treatment system 
received process water from the coil coating process line from the 
initial wash and rinse phase and from the chemical processing phase. 
The pH was adjusted and the solid materials were precipitated. When 
steel or galvanized coils were processed, wastewater treatment sludges 
were generated which were not listed RCRA hazardous waste. The F019 
listed wastes were generated when aluminum coils were processed. Both 
the listed and the non-listed sludges were commingled and pumped into 
several on-site surface impoundments for settling and drying. In 1965 
and 1966, sludges were transferred to surface impoundments for settling 
and drying. From 1968 to 1978, this sludge was transferred from the 
surface impoundments to the landfill or were disposed of off-site. 
Sludges that were placed in the landfill were co-mingled with other 
waste debris. The landfill was covered with a layer of clay soils 
obtained from an off-site highway construction project. In 1978, the 
use of the landfill was discontinued and the landfill was covered with 
approximately 1 to 5 feet of fill soils.
    The AMC WWTP would batch treat process wastewater from the coil 
coating final hot rinse step in order to reduce hexavalent chromium to 
trivalent chromium. The wastewater was treated with sodium 
metabisulfite and emptied once a week into the chemical sump for 
further treatment in the WWTP.

D. How Did USG Sample and Analyze the Data in This Petition?

    USG analyzed the landfilled sludge and groundwater samples from the 
monitoring well network for hazardous constituents listed in 40 CFR 
Part 264, Appendix IX and for other parameters.
    USG's sampling strategy consisted of dividing the landfill surface 
area into four equal quadrants. One boring was drilled near the center 
of each quadrant. One composite sample representing the total depth of 
the landfill was collected and submitted. The Agency evaluated the 
petitioned waste using these four samples in combination with data from 
the RCRA Facility Investigation (up to 20 additional samples) and 
subsequent waste designation studies (up to 13 additional samples).
    To quantify the total constituent and leachate concentrations, USG 
used the following SW-846 Methods: 6010/7000 series for antimony, 
arsenic, barium, beryllium, cadmium, chromium, hexavalent chromium, 
cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, 
silver, thallium, tin, vanadium, and zinc; 8240 for Appendix IX 
Volatile Organic Compounds (VOCs); 8270 for Appendix IX Semi-Volatile 
Organic Compounds (SVOCs); 8080 for organochlorine pesticides and 
polychlorinated biphenyls (PCBs); 8140 for organochlorine pesticides; 
8150 for chlorinated herbicides. USG used these methods along with the 
Toxicity Characteristic Leaching Procedure (TCLP, SW-846 Method 1311) 
to determine leachate concentrations of metals, herbicides, pesticides, 
PCBs, VOCs, and SVOCs. Characteristic testing of the filter cake 
samples also included analysis of ignitability (SW-846 Method 1010) and 
corrosivity (SW-846 Method 9095). Historical analysis for dioxins and 
furans was done using method 8280. More recent dioxins and furans data 
was submitted using EPA Method 8290.

E. What Were the Results of USG's Analysis?

    The maximum total and leachate concentrations for 17 metals, total 
cyanide and all detected organic

[[Page 58018]]

constituents in USG's waste samples are summarized in the table found 
in section VI.A. below. We believe it is inappropriate to evaluate a 
constituent in our modeling efforts if the constituent was not detected 
using an appropriate analytical method. EPA does not generally verify 
submitted test data before proposing delisting decisions. The sworn 
affidavit submitted with the petition binds the petitioner to present 
truthful and accurate results. USG submitted a signed Certification of 
Accuracy and Responsibility statement presented in 40 CFR 
260.22(i)(12).

IV. Methodology for Risk Assessment

A. How Did EPA Evaluate the Risk of Delisting This Waste?

    For this delisting determination, we used information gathered to 
identify plausible exposure routes (i.e., groundwater, surface water, 
air) to hazardous constituents present in the petitioned waste. We 
estimated the risk posed by the waste if disposed of in an unlined 
Subtitle D landfill which, under a plausible mismanagement scenario, 
did not receive daily cover for 30 days at a time. Constituents of 
concern are assumed to migrate to a receptor through groundwater, air, 
and surface water routes. We used a Windows based software tool, the 
Delisting Risk Assessment Software Program (DRAS) developed by Region 
6, to estimate the potential releases of waste constituents and to 
predict the risk associated with those releases. A detailed description 
of DRAS and the fate, transport and risk models it uses follows.
1. Introduction
    During a delisting determination, the Agency uses risk assessment 
methodologies to predict the concentration of hazardous constituents 
released from the petitioned waste after disposal to determine the 
potential impact on human health and the environment. The DRAS Program 
has been used to estimate the potential releases of waste constituents 
to waste management units. The program also predicts the risk 
associated with exposure to those releases using fate and transport 
mechanisms to predict releases and risk assessment algorithms to 
estimate adverse effects from exposure to those chemical releases. The 
DRAS computes chemical-specific exit values or ``delisting levels.'' 
The delisting levels are calculated using modeled, medium-specific 
chemical concentrations and standard EPA exposure assessment and risk 
characterization algorithms. We detailed all chemical release, 
exposure, and risk characterization methodologies in the EPA Region 6 
RCRA Delisting Technical Support Document.
    The Agency has used the maximum estimated annual waste volume and 
the maximum reported leachate and total waste constituent 
concentrations as the input data into the DRAS program to generate 
compliance point concentrations and estimate risk. The compliance point 
is the location of an individual exposed to potential releases of 
delisted wastes for the purpose of evaluating risk. Compliance point 
concentrations are generated in a two-part process. First, the DRAS 
back-calculates a waste constituent concentration that an individual 
(receptor) may be exposed to without unacceptable risk. Then, knowing 
the maximum concentration permitted at the compliance point, the fate 
and transport models are used to back-calculate the maximum permissible 
concentration at the waste management unit that could be disposed of 
without exceeding the compliance point concentration.
    The risk assessment performed by the DRAS program which underlies 
the proposed rule is based upon a comprehensive approach to evaluating 
the movement of waste constituents from their waste management units, 
through different routes of exposure or pathways, to the points where 
human and ecological receptors are potentially exposed to these 
constituents. This risk assessment is being used in today's proposed 
rule to determine whether the petitioned RCRA listed waste can be 
defined as ``low-risk'' waste, able to exit the Subtitle C system and 
be managed in Subtitle D units. Low risk wastes are generally defined 
by Region 5 as wastes with a cancer risk of no more than 
1 x 10-6 or a hazard quotient of no more than 1.0. A cancer 
risk of 1 x 10-6 indicates a one in 1,000,000 probability of 
an individual developing cancer over a lifetime. For noncarcinogenic 
chemicals, a hazard quotient of one represents potential exposure equal 
to the safe toxicity threshold value. The program back-calculates 
allowable waste constituent concentrations at the selected risk levels.
    Although the pathway of ingestion of contaminated groundwater may 
be appropriate to propose exit levels for some wastes and constituents, 
it may not be protective for others, depending on the physical and 
chemical properties of each waste constituent. Some constituents have a 
high potential to bioaccumulate or bioconcentrate in living organisms. 
Pathways in which these constituents come in contact with fish would be 
important to evaluate.
    The DRAS program performs an extensive risk assessment that 
examines numerous exposure pathways, rather than just the groundwater 
ingestion pathway. The DRAS program evaluates exposures associated with 
managing wastes in Subtitle D landfills or surface impoundments. 
Elements of the risk assessment procedure performed by the DRAS that 
support this proposal have undergone review by the Science Advisory 
Board and EPA's Office of Research and Development. The use of CMTP as 
used in the DRAS was favorably received by the SAB. ORD reviewed all 
other aspects of the DRAS program and responded favorably with 
comments. All ORD comments were addressed and incorporated into the 
DRAS program.
2. What Conditions Does the Agency Use in Determining Whether a Waste 
May Be Delisted?
    The EPA's approach in RCRA delisting risk analyses has typically 
been to represent a reasonable worst-case waste disposal scenario for 
the petitioned waste rather than use of site-specific factors. The 
Agency believes that a reasonable worst-case scenario results in 
conservative values for the compliance point concentrations and is 
appropriate when determining whether a waste should be relieved of the 
management constraints of RCRA Subtitle C. Site-specific factors (e.g., 
site hydrogeology) are not considered because a delisted waste is no 
longer subject to hazardous waste control, and therefore, the Agency is 
generally unable to predict and does not control where and how a waste 
will be managed after delisting.
3. How Is the Risk Assessment in the DRAS Program Structured?
    The assessment estimated the risk associated with constituent-
specific concentrations in the petitioned waste at the management unit 
that could be expected to result in an acceptable exposure to human or 
ecological receptors (determined through using the toxicity benchmarks 
such as reference doses--RfDs). The risk assessment took into account 
the various pathways by which waste constituents may move through the 
environment from the waste management unit to a receptor. The DRAS uses 
the fate and transport mechanisms to predict waste constituent 
movement. The potential exposure pathways considered in the assessment 
are not all-inclusive but were selected to reflect those that might be 
commonly associated with the management of wastes in Subtitle D units. 
The management units could

[[Page 58019]]

potentially be located in the range of environments that exist across 
the United States. Various environments have differing characteristics 
(e.g., meteorological conditions, soil type) with some environments 
more conducive for the movement of certain constituents in certain 
pathways. Conditions resulting in a conservative evaluation were used 
for each pathway, regardless of whether or not these conditions are 
likely to occur simultaneously at any one location. The assessment was 
structured using a deterministic approach. A deterministic approach 
uses a single, point estimate of the value of each input or parameter 
and calculates a single result based on those point estimates. The 
assessment used the best data available to select typical (i.e., 
approximately 50th percentile) and high-end (i.e., approximately 90th 
percentile) values for each parameter or parameter. The DRAS code which 
performs the assessment is constructed as a set of calculations that 
begin with an acceptable exposure level for a constituent to a 
receptor, and back-calculates to a waste constituent concentration in 
the management unit that corresponds to the acceptable risk level.
    The steps of the assessment which provide estimates of acceptable 
constituent-specific concentrations in waste include the following:
    Step 1--Specify acceptable risk levels for each constituent and 
each receptor.
    Step 2--Specify the exposure medium. Using the toxicity benchmarks 
as a starting point and the exposure equations, the assessment back 
calculates the concentration of contaminant in the medium (e.g., air, 
water, soil) that corresponds to ``acceptable'' exposure at the 
specified risk level. The exposure equations coded into the DRAS 
software include a quantitative description of how a receptor comes 
into contact with the contaminant and how much the receptor takes in 
through specific mechanisms (e.g., ingestion, inhalation, dermal 
adsorption) over some specified period of time.
    Step 3--Calculate the point of release concentration from the 
exposure concentration. Based on the back-calculated concentration in 
the exposure medium (from Step 2), the concentration in the medium to 
which the contaminant is released to the environment (i.e., air, soil, 
groundwater) for each pathway/receptor was modeled. The end result of 
this calculation is a waste constituent concentration at the point of 
release from the waste management unit (where the exempted waste is 
disposed) that will not result in adverse effects to human health and 
the environment.
4. When Assessing the Risk of the Exempted Waste, Where Does the DRAS 
Assume the Waste is Deposited?
    The DRAS risk assessment evaluates risks associated with petitioned 
RCRA wastes deposited to two waste management scenarios: landfills and 
surface impoundments. A landfill waste management scenario is used for 
the evaluation of solid wastes, while a surface impoundment waste 
management scenario is used for the evaluation of liquid wastes. The 
determination of whether a waste is a liquid waste is made using EPA 
approved Test Method 9095, referred to as the Paint Filter Test. Data 
to characterize landfills were obtained from a 1987 nationwide survey 
of industrial Subtitle D landfills. For releases to groundwater, EPA's 
Composite Model for leachate migration with Transformation Products 
(EPACMTP) fate and transport model was used by DRAS. The model assumes 
that solid wastes remain uncovered for thirty days after disposal and 
that the landfill will finally be covered with a 2-foot-thick native 
soil layer. The Subtitle D landfill is assumed to be unlined or if 
lined, that any liner at the base of the landfill will eventually 
completely fail.
    The DRAS assumes that liquid industrial wastes are disposed of in 
an unlined surface impoundment with a sludge or sediment layer at the 
base of the impoundment and that releases of contaminants originate 
from the surface impoundment. The surface impoundment is taken to have 
a 20-year operational life. After this period, the impoundment may be 
filled in, or simply abandoned. In either case, the remaining waste in 
the impoundment will leach into the unsaturated zone relatively 
quickly. Therefore, the duration of the leaching period in the modeling 
analysis is set equal to 20-years.
5. What Types of Chemical Releases From the Waste Management Units Does 
the DRAS Evaluate?
    The DRAS evaluates chemical releases of waste constituents from the 
waste management units to air, surface runoff and ground water. Using 
the EPACMTP fate and transport model, DRAS evaluates the potential 
release of waste contaminants to the ground water. In this evaluation, 
the differences between waste management units are represented by 
different values or frequency distributions of the source-specific 
parameters. Source-specific parameters used by the EPACMTP predict 
releases to the ground water from landfills include:
     Capacity and dimensions of the waste management unit;
     Leachate concentration;
     Infiltration and recharge rates;
     Pulse duration;
     Fraction of hazardous waste in the waste management unit;
     Density of the waste and;
     Concentration of the chemical constituent in the hazardous 
waste.
    The source-specific parameters used by the model for surface 
impoundments include:
     The area;
     The ponding depth (such as the depth of liquid in the 
impoundment) and;
     The thickness and hydraulic conductivity of the sludge or 
sediment layer at the bottom of the impoundment.
    Data on the areas, volumes, and locations of waste management units 
were obtained from the 1987 EPA Survey of Industrial Subtitle D waste 
facilities in the United States. Derivation of the parameters for each 
type of waste management unit is described in the EPACMTP Background 
Document and User's Guide.
    For finite-source scenarios, simulations are performed for 
transient conditions, and the source is assumed to be a pulse of finite 
duration. In the case of landfills, the pulse duration is based on the 
initial amount of contaminant in the landfill, infiltration rate, 
landfill dimensions, waste and leachate concentration, and waste 
density. For surface impoundments, the duration of the leaching period 
is determined by the waste management unit's lifetime (the default 
value is 20 years). For a finite-source scenario, the model can 
calculate either the peak receptor well concentration for 
noncarcinogens or an average concentration over a specified period for 
carcinogens. The finite-source methodology in the EPACMTP is discussed 
in detail in the background document.
    The DRAS evaluates releases of waste constituents from the waste 
management to the air. Releases of chemicals to the air may be in the 
form of either particulates or volatile concentrations. Inhalation of 
particulates and their absorption into the lungs at the point of 
exposure (POE) and air deposition of particulates and subsequent 
ingestion of the soil-waste mixture at the POE are a function of 
particulate releases. The DRAS calculates particulate emissions 
resulting from wind erosion of soil-waste surfaces, from vehicular 
traffic, and from waste loading and unloading. To estimate the 
respirable particulate

[[Page 58020]]

emissions resulting from wind erosion of surfaces with an infinite 
source of erodible particles, DRAS uses the methodology documented in 
Rapid Assessment of Exposure to Particulate Emissions from Surface 
Contamination Sites (RAEPE). The methodologies documented in 
Compilation of Air Pollutant Emission Factors, Volume 1: Stationary 
Point and Area Sources (AP-42) were employed to calculate the dust and 
particulate emissions resulting both from vehicular traffic and from 
waste loading and unloading operations at a facility.
    Particulate emission rates computed using these methodologies were 
summed and entered in the Ambient Air Dispersion Model, a steady-state, 
Gaussian plume dispersion model developed by EPA to predict the 
concentrations of constituents 1,000 feet downwind of a hypothetical 
land disposal facility. For a complete description and discussion, 
refer to the 1985 Ambient Air Dispersion Model (AADM). The model 
assumes that:
    1--the emission rate is constant over time;
    2--the emissions arise from an upwind virtual point source with 
emissions occurring at ground level and;
    3--no atmospheric destruction or decay of the constituent occurs.
    The DRAS assumes typical or conservative values for all variables 
that are likely to influence the potential for soil erosion, including 
wind velocity and vegetative cover. The AADM unit dimension assumptions 
were modified to more closely resemble a landfill's. The DRAS equations 
compute emissions resulting from wind erosion, vehicular traffic, and 
waste loading and unloading. These equations are thoroughly described 
in the Region 6 Delisting Technical Support Document. For the landfill 
waste disposal scenario, the DRAS assumed that no vegetative cover is 
present, thereby assuming enhanced erodability of soil or waste. The 
mean annual wind speed is assumed to be 4 meters per second. This value 
represents the average of the wind speeds registered at U.S. 
climatological stations as documented in Table 4-1 of RAEPE. The DRAS 
assumes a month's (30 days') worth of waste would be uncovered at any 
one time.
    Although particulates greater than 10 micrometers (m) in 
size generally are not considered respirable, the DRAS calculates the 
emission rate for particle sizes up to 30 m in order to assess 
the potential impact of deposition and ingestion of such particulates 
using the distributions of wind-eroded particulates presented in RAEPE. 
Specifically, these distributions indicate that the release rate for 
particulates up to 30 m in size should be approximately twice 
the release rate calculated for particulates 10 m in size. The 
DRAS calculates the total annual average emissions of respirable 
particulates by summing for wind erosion, for vehicle travel, and for 
waste loading and unloading operations. The DRAS evaluates air 
deposition of the annual total emissions of particulates less than or 
equal to 30 m in size to soil 1,000 feet from the edge of a 
disposal unit. DRAS calculates the resulting soil concentration after 
one year of accumulation, conservatively assuming no constituent 
removal (no leaching, volatilization, soil erosion, or degradation).
    The DRAS also evaluates the atmospheric transport and inhalation of 
volatile constituents which was developed by EPA's Office of Air 
Quality Planning and Standards (OAQPS) and has been recommended for use 
in risk assessments conducted under the Superfund program. The DRAS 
program, is currently being revised to incorporate Shen's modification 
of Farmer's equation which will result in a better estimate of volatile 
emissions. Since the maximum concentration of volatiles in USG's waste 
is low, this pathway will not be reevaluated using the revised 
approach, unless the revised version of DRAS becomes available. 
Estimates of emissions of VOCs from disposal of wastewaters in surface 
impoundments are computed with EPA's Surface Impoundment Modeling 
System (SIMS). SIMS was developed by EPA's OAQPS. Further information 
can be found in the Background Document for the Surface Impoundment 
Modeling System Version 2.0. The volatile emission rates derived from 
the respective waste management scenario are used by the AADM steady-
state Gaussian plume dispersion model to predict the concentrations of 
constituents 1,000 feet downwind of a hypothetical disposal facility.
    The DRAS evaluates potential releases of waste constituents to 
accessible surface waters. Exposure through the surface water pathway 
results from erosion of hazardous materials from the surface of a solid 
waste landfill and transport of these constituents to nearby surface 
water bodies. The DRAS uses the universal soil loss equation (USLE) to 
compute long-term soil and waste erosion from a landfill in which 
delisted waste has been disposed of. The USLE is used to calculate the 
amount of waste that will be eroded from the landfill. In addition, the 
size of the landfill is computed using the waste volume estimate 
provided by the petitioner. The volume of surface water into which 
runoff occurs is determined by estimating the expected size of the 
stream into which the soil is likely to enter. The amount of soil 
delivered to surface water is calculated using a sediment delivery 
ratio. The sediment delivery ratio determines the percentage of eroded 
material that is delivered to surface water based on the assumption 
that some eroded material will be redeposited between the landfill and 
the surface water body. A distance of 100 meters (m) to the nearest 
surface water body is assumed. The DRAS program as used here is 
currently being revised to account for partitioning between water and 
suspended solids when the eroded waste enters the stream. Due to the 
significant impact of this pathway in the evaluation of USG's petition, 
the risk posed through this pathway was reevaluated manually using the 
same partitioning approach which is being incorporated into the next 
version of the DRAS program (See the Docket Report on Evaluation of 
Contaminant Releases to Surface Water Resulting from American Metals' 
Petitioned Waste). Conservative values are used in the manual 
recalculation for variables likely to influence the potential for soil 
erosion and subsequent discharge to surface water. Rainfall erosion 
factor values range from 20 to 550 per year. Values greater than 300 
occur in only a small proportion of the southeastern United States. A 
value of 300 was chosen as a conservative estimate ensuring that a 
reasonable worst-case scenario is provided for most possible landfill 
locations. Soil erodibility factors range from 0.1 to 0.69 ton per 
acre. A value of 0.3 was selected for the analysis, which is estimated 
to exceed 66% of all values assuming a normal distribution. One month's 
worth of waste is assumed to be left uncovered at any one time and thus 
would be readily transportable by surface water runoff. Other variables 
used by the DRAS and in the manual calculation to evaluate releases to 
surface waters employed conservative assumptions. Both the DRAS and the 
manual recalculation multiply the total annual mass of eroded material 
by the sediment delivery ratio to determine the mass of soil and waste 
delivered to surface water.
    The predicted erosion capacity is gradually diluted as it mixes 
with nearby surface waters. DRAS selects a representative volume or 
flux rate of surface water based on stream order, which is a system of 
taxonomy for streams and rivers. A stream that has no other streams 
flowing into it is referred to as a first-order stream. Where two

[[Page 58021]]

first-order streams converge, a second-order stream is created. Where 
two second-order streams converge, a third-order stream is created. 
Data indicate that second-order streams have an estimated flow rate of 
3.7 cubic feet per second. The second-order stream was selected for 
analysis as the smallest stream capable of supporting recreational 
fishing. Fifth-order streams were also chosen for analysis as the 
smallest streams capable of serving as community water supplies. Fifth-
order stream flow is estimated to be 380 cubic feet per second.
6. By What Means May an Individual Be Exposed to the Proposed Exempted 
Waste?
    An exposure scenario is a combination of exposure pathways through 
which a single receptor may be exposed to a waste constituent. 
Receptors may be human or other animal in an ecosystem. There are many 
potential exposure scenarios. The DRAS evaluated the risks of the 
proposed waste associated with the exposure scenarios most likely to 
occur as a result of releases from the waste management unit. Receptors 
may come into contact with delisted waste constituent releases from a 
waste management unit via two primary exposure routes, either (1) 
directly via inhalation or ingestion of water or (2) indirectly via 
subsequent ingestion of soil and foodstuffs (such as fish) that become 
contaminated by waste constituents through the food chain. Receptors 
may also be exposed to waste constituents released from a waste 
management unit to surface media (via volatilization to air or via 
windblown particulate matter) or to groundwater (via ingestion of 
groundwater). The exposure scenarios assessed by DRAS are generally 
conservative in nature and are not intended to be entirely 
representative of actual scenarios at all sites. Rather, they are 
intended to allow standardized and reproducible evaluation of risks 
across most sites and land use areas. Conservatism is incorporated to 
ensure protection of potential receptors not directly evaluated, such 
as special subpopulations. The recommended exposure scenarios and 
associated assumptions assessed by DRAS are reasonable and conservative 
and they represent a scientifically sound approach that allows 
protection of human health and the environment.
7. What Receptors Are Assessed for Risk From Exposure to the Proposed 
Exempted Waste?
    Adult and child residents are the two receptors evaluated in this 
analysis. The adult resident exposure scenario is evaluated to account 
for the combination of exposure pathways to which an adult receptor may 
be exposed in an urban or rural (nonfarm) setting. The adult resident 
is assumed to be exposed to waste constituents from an emission source 
through the following exposure pathways:
    1--Direct inhalation of vapors and particles;
    2--Ingestion of fish;
    3--Ingestion of drinking water from surface water sources;
    4--Ingestion of drinking water from groundwater sources;
    5--Dermal absorption from groundwater sources via bathing;
    6--Inhalation from groundwater sources via showering.
    DRAS evaluates two exposure pathways for children: (1) dermal 
absorption while bathing with potentially contaminated groundwater and 
(2) the ingestion of soil containing contaminated particulates which 
have need emitted from the landfill and deposited on the soil. Child 
residents (1 to 6 years old) were not selected as receptors for the 
groundwater ingestion and inhalation pathways, the surface water 
pathways, or the direct air inhalation pathways because the adult 
resident receptor scenario has been found to be protective of children 
with regard to these pathways. There is no indication that children 
consume more drinking water or inhale more air per unit of body weight, 
factoring in the recognized exposure duration, than adults. Therefore, 
average daily exposure normalized to body weight would be identical for 
adults and children. Likewise, a child receptor was not included for 
the freshwater fish ingestion pathway because there is no evidence that 
children consume more fish relative to their body weight, factoring in 
exposure duration, than do adults. The dermal absorption while bathing 
with groundwater exposure pathway is evaluated differently for child 
residents than it is for adult residents because of the following 
considerations: (1) The ratio of exposed skin surface area to body 
weight is slightly higher for children than for adults, resulting in a 
slightly larger average daily exposure for children than for adults; 
and (2) the exposure duration for such children is limited to 6 years, 
thus lowering the lifetime average exposure to carcinogens. Typically, 
the adult scenario is more protective with regard to carcinogens 
(because of the longer exposure duration), and the child scenario is 
more protective with regard to noncarcinogens (because of the greater 
skin surface area to body weight ratio).
8. Where Does the DRAS Assume That Receptors Are Located When 
Performing the Risk Evaluation?
    The EPACMTP, a probabilistic groundwater fate and transport model, 
was used to predict groundwater constituent concentrations at a 
hypothetical receptor well located downgradient from a waste management 
unit. This receptor well represents the POE. That is, the predicted 
waste constituent concentration at the POE is used to assess the risk 
of the proposed exempted waste. The distance to the well is based on 
the results of the 1987 nationwide survey of landfills conducted by 
EPA's Office of Solid Waste (OSW) which determined the distance to the 
nearest drinking water well downgradient from municipal landfills. The 
survey data are entered in the EPACMTP model as an empirical 
distribution: minimum = 0 m, median = 427 m, and maximum = 1,610 m 
(approximately 1 mile). In contrast to the 1990 Toxicity Characteristic 
(TC) Rule (55 FR 11798), there is no requirement that the well lie 
within the leachate plume.
    For carcinogenic waste constituents, the exposure concentration is 
defined as the maximum 30 year average receptor well concentration; for 
noncarcinogens, the exposure concentration is taken to be the highest 
receptor well concentration during the modeled 10,000 year period. A 
10,000 year limit was imposed on the exposure period; that is, the 
calculated exposure concentration is the peak or highest 30 year 
average concentration occurring within 10,000 years following the 
initial release from the waste management unit. The fate and transport 
simulation within the CMTP provided a probability distribution of 
receptor well concentrations as a function of expected leachate 
concentration. Using the receptor well concentrations as a function of 
the waste constituent concentration, the EPACMTP derived chemical-
specific dilution attenuation factors (DAFs) which convert a leachate 
concentration in the landfill to a groundwater concentration at the 
receptor well.
    Human exposure routes for surface water include ingestion of 
surface water used as drinking water and ingestion of fish from nearby 
surface water bodies. For the surface water ingestion exposure route, 
the surface water POE modeled is a fifth-order stream 100 m from the 
waste management unit. Fifth-order streams were chosen for analysis 
because EPA assumes that a fifth-order

[[Page 58022]]

stream is the smallest stream capable of serving as a community water 
supply. The assumption of a 100 m distance to the nearest surface water 
body is a conservative assumption based on available data. An EPA 
survey of municipal landfill facilities showed that 3.6 percent of the 
surveyed facilities are located within 1 mile of a river or stream and 
that the average distance from these facilities to the closest river or 
stream is 586 m. For the fish ingestion exposure route, a second-order 
stream was chosen for analysis. This stream segment was determined to 
be the smallest stream capable of supporting fisheries. The POE in the 
surface water body for collection of fish is assumed to be 100 m 
downgradient from the disposal facility. Human exposure to emissions of 
windblown particulates from landfills and to emissions of volatiles 
from landfills and surface impoundments is assessed by the DRAS. For 
the air pathway, the DRAS assumes the POE is 305 m (1,000 feet) 
downwind of the waste management unit.
9. How Does DRAS Determine Rates of Exposure?
    The calculation of constituent-specific exposure rates for each 
exposure pathway evaluated were based on:
    1--The estimated concentration in a given medium as calculated in 
DRAS;
    2--The contact rate;
    3--Receptor body weight, and;
    4--The frequency and duration of exposure.
    This calculation is repeated for each constituent and for each 
exposure pathway included in an exposure scenario. Exposure to 
hazardous constituents is assumed to occur over a period of time. To 
calculate an average exposure per unit of time, the DRAS divides the 
total exposure by the time period. Exposures are intended to represent 
reasonable maximum exposure (RME) estimates for each applicable 
exposure route. The RME approach is intended to combine upper-bound and 
mid-range exposure factors so that the result represents an exposure 
scenario that is both protective and reasonable, not the worst possible 
case.
10. What Rate of Contact With a Contaminated Media Does the DRAS Use?
    The contact rate is the amount of contaminated medium contacted per 
unit of time or event. Contact rates for subsistence food types (fish 
for the fish ingestion pathway) are assumed to be 100 percent from the 
hypothetical assessment area (surface water body). The following 
sections describe exposure pathway-specific contact rates.
11. What Are the Contact Rates at Which Individuals Are Exposed to 
Contaminated Media?
    For groundwater and surface water ingestion, the intake rate is 
assumed to be 2.0 liters per day (l/day), the average amount of water 
that an adult ingests. This value, which is currently used to set 
drinking water standards, is close to the current 90th percentile value 
for adult drinking water ingestion (2.3l/day) reported in the EPA 
Exposure Factors Handbook. This value approximates the 8 glasses of 
water per day historically recommended by health authorities. The 
contact for the dermal exposure pathway is assumed to occur while 
bathing with contaminated groundwater. In this analysis, the DRAS 
assumes that the average adult resident is in contact with groundwater 
during bathing for 0.25 hour per event and that the average child 
resident is in contact with groundwater during bathing for 0.33 hour 
per event, with one event per day. For dermal bathing exposure to 
contaminated groundwater, the selected receptors are an adult and a 
young child (1 to 6 years old). During bathing, generally all of the 
skin surface is exposed to water. The total adult body surface area can 
vary from about 17,000 to 23,000 square centimeters (cm\2\). The EPA 
Exposure Factors Handbook (EFH) reports a value of 20,000 cm\2\ as the 
median value for adult skin surface area. A value of 6,900 cm\2\ has 
been commonly used for a child receptor in EPA risk assessments; this 
value is approximately the average of the median values for male 
children aged 2 to 6. The EFH presents a range of recommended values 
for estimates of the skin surface area of children by age. The mean 
skin surface area at the median for boys and girls 5 to 6 years of age 
is 0.79 square meters (m\2\) or 7,900 cm\2\. Given that the age for 
children is defined as 0 to 6 years (see EFH Section 3.3.4), a skin 
surface area value for ages 5 to 6 years would be a conservative 
estimate of skin surface area for children. For calculation of dermal 
exposure to waste constituents, the DRAS uses a value of 7,900 cm\2\ 
for the skin surface area of children and a value of 20,000 cm\2\ for 
the skin surface area of adults.
    For the groundwater pathway of inhalation exposure during 
showering, the contact with water is assumed to occur principally in 
the shower and in the bathroom. The DRAS analysis assumes that the 
average adult resident spends 11.4 minutes per day in the shower and an 
additional 48.6 minutes per day in the bathroom. Daily inhalation rates 
vary depending on activity, gender, age, and so on. Citing a need for 
additional research, the EFH does not recommend a reasonable upper-
bound inhalation rate value. The EFH recommended value for the average 
inhalation rate is 15.2 cubic meters per day (m\3\/day) for males and 
11.3 m\3\/day for females. The EPA established an upper-bound value for 
an individual's inhalation rate at 20 m\3\/day which has been commonly 
used in past EPA risk assessments. This value is used by the DRAS for 
assessment of inhalation exposure.
    The DRAS assesses the ingestion of soil contaminated with air-
deposited particulates from a nearby landfill. The potential for 
exposure to constituents via soil ingestion is greater for children 
because they are more likely to ingest more soil than adults as a 
result of behavioral patterns present during childhood. Therefore, 
exposure to waste constituents through ingestion of contaminated soils 
is evaluated for the child in a delisting risk assessment. The mean 
soil ingestion values for children range from 39 to 271 milligrams per 
day (mg/day), with an average of 146 mg/day for soil ingestion and 191 
mg/day for soil and dust ingestion (see EPA EFH). Based on the EFH 
statement that 200 mg/day may be used as a conservative estimate of the 
mean, the DRAS uses 200 mg/day as the soil ingestion rate for children.
    Fish consumption rates vary greatly, depending on geographic region 
and social or cultural factors. The recommended value for fish 
consumption for all fish is 0.28 grams of fish per kilogram body weight 
per day for an average adult (see EPA EFH). This value equates with a 
fish consumption rate of 20.1 grams per day (g/day) for all fish. The 
DRAS estimated that an exposed individual eats 20 g of fish per day, 
representing one 8-ounce serving of fish approximately once every 11 
days.
    A consumption rate of 57.9 g/day was used in the manual 
reevaluation of risk posed through fish ingestion. This higher 
consumption rate, corresponding to a high-risk subpopulation present in 
Region 5 (low income minority sport fisherman) was added to the 
evaluation for USG's waste at the request of Regional risk assessors.
12. At What Frequency Does the DRAS Assume That Receptors Are Exposed 
to Contaminated Media?
    An exposure frequency of 350 days per year is applied to all 
exposure scenarios (see EPA EFH). Until better data become available, 
the common assumption that residents take 2 weeks

[[Page 58023]]

of vacation per year is used to support a value of 15 days per year 
spent away from home, leaving 350 days per year spent at home and 
susceptible to exposure.
13. For What Duration Does the DRAS Assume Receptors Are Exposed to 
Contaminated Media?
    The exposure duration reflects the length of time that an exposed 
individual may be expected to reside near the constituent source. For 
the adult resident, this value is taken to be 30 years, and for the 
child resident, this value is taken to be 6 years (see EPA EFH). The 
adult resident is assumed to live in one house for 30 years, the 
approximate average of the 90th percentile residence times from two key 
population mobility studies. For the child resident, the exposure 
duration is assumed to be 6 years, the maximum age of the young child 
receptor. For carcinogens, exposures are combined for children (6 
years) and adults (24 years). For noncarcinogenic constituents, the 
averaging time (AT) equals the exposure duration in years multiplied by 
365 days per year. For an adult receptor, the exposure duration is 30 
years, and for a child receptor, the exposure duration is 6 years. For 
carcinogenic constituents, the AT has typically been 25,550 days, based 
on a lifetime exposure of 70 years at 365 days per year. The life 
expectancy value in the EFH is 75 years. Given this life expectancy 
value, the AT for a delisting risk assessment is 27,375 days, based on 
a lifetime exposure of 75 years at 365 days per year.
14. What Body Weights Are Assumed for Receptors in the DRAS Evaluation?
    Risk Assessment Guidance for Superfund defines the body weight of 
the receptor as either adult weight (70 kilograms (kg)) or child weight 
(1 to 6 years, 15 kg). The EFH recommended value of 71.8 kg for an 
adult differs from the 70-kg value commonly used in EPA risk 
assessments. In keeping with the latest EFH recommendation, the DRAS 
used a 72-kg adult weight and a 15-kg child weight for the proposed 
delisting determination.

B. What Risk Assessment Methods Has the Agency Used in Previous 
Delisting Determinations That Are Being Revised in This Proposal?

1. Introduction
    The fate and transport of constituents in leachate from the bottom 
of the waste unit through the unsaturated zone and to a drinking water 
well in the saturated zone was previously estimated using the EPA 
Composite Model for Landfill (EPACML) (See 55 FR 11798). The EPACML 
accounts for:
     One-dimensional steady and uniform advective flow;
     Contaminant dispersion in the longitudinal, lateral, and 
vertical directions;
     Sorption.
    However, advances in groundwater fate and transport have been made 
in recent years and the Agency proposes the use of a more advanced 
groundwater fate and transport model for RCRA exclusions.
2. What Fate and Transport Model Does the Agency Use in the DRAS for 
Evaluating the Risks to Groundwater From the Proposed Exempted Waste?
    The Agency proposes to use the EPACMTP in this delisting 
determination. The EPACMTP considers the subsurface fate and transport 
of chemical constituents. The EPACMTP is capable of simulating the fate 
and transport of dissolved contaminants from a point of release at the 
base of a waste management unit, through the unsaturated zone and 
underlying groundwater, to a receptor well at an arbitrary downstream 
location in the aquifer. The model accounts for the following 
mechanisms affecting contaminant migration: transport by advection and 
dispersion, retardation resulting from reversible linear or nonlinear 
equilibrium adsorption onto the soil and aquifer solid phase, and 
biochemical degradation processes.
3. Why Is the EPACMTP Fate and Transport Model an Improvement Over the 
EPACML?
    The modeling approach used for this proposed rulemaking includes 
three major categories of enhancements over the EPACML. The 
enhancements include:
    1--Incorporation of additional fate and transport processes (e.g., 
degradation of chemical constituents);
    2--Use of enhanced flow and transport solution algorithms and 
techniques (e.g., three-dimensional transport) and;
    3--Revision of the probabilistic methodology (e.g., site-based 
implementation of available input data)

A discussion of the key enhancements which have been implemented in the 
EPACMTP is presented here and the details are provided in the proposed 
1995 Hazardous Waste Identification Rule (HWIR) background documents 
(60 FR 66344-December 21, 1995).
    The EPACML was limited to conditions of uniform groundwater flow. 
It could not handle accurately the conditions of significant 
groundwater mounding and non-uniform groundwater flow due to a high 
rate of infiltration from the waste units. These conditions increase 
the transverse horizontal as well as the vertical spreading of a 
contaminant plume. The EPACMTP accounts for these effects directly by 
simulating groundwater flow in the vertical as well as horizontal 
directions.
    The EPACMTP can simulate fate and transport of metals, taking into 
account geochemical influences on the mobility of metals. The EPA's 
MINTEQA2 metals speciation model is used to generate effective sorption 
isotherms for individual metals, corresponding to a range of 
geochemical conditions. The transport modules in EPACMTP have been 
enhanced to incorporate the nonlinear MINTEQ sorption isotherms. This 
enhancement provides the model with capability to simulate, in the 
unsaturated and in the saturated zones, the impact of pH, leachate 
organic matter, natural organic matter, iron hydroxide and the presence 
of other ions in the groundwater on the mobility of metals. The 
saturated zone module implemented in the EPACML was based on a Gaussian 
distribution of concentration of a chemical constituent in the 
saturated zone. The module also used an approximation to account for 
the initial mixing of the contaminant entering at the water table 
underneath the waste unit. The approximate nature of this mixing factor 
could sometimes lead to unrealistic values of contaminant concentration 
in the groundwater close to the waste unit, especially in cases of a 
high infiltration rate from the waste unit. The enhanced model 
incorporates a direct linkage between the unsaturated zone and 
saturated zone modules which overcomes these limitations of the EPACML.
    To enable a greater flexibility and range of conditions that can be 
modeled, the analytical saturated zone transport module has been 
replaced with a numerical module, based on the highly efficient state-
of-the-art Laplace Transform Galerkin (LTG) technique. The enhanced 
module can simulate the anisotropic, non-uniform groundwater flow, and 
transient, finite source, conditions. The latter requires the model to 
calculate a maximum receptor well concentration over a finite time 
horizon, rather than just the steady state concentration which was 
calculated by the EPACML. The saturated zone modules have been 
implemented to provide either a fully three-dimensional solution, or a 
highly efficient quasi-3D solution. The latter has been implemented for 
probabilistic

[[Page 58024]]

applications and provides nearly the same accuracy as the fully three 
dimensional option, but is more computationally efficient. Both the 
unsaturated zone and the saturated zone transport modules can 
accommodate the formation and the transport of parent as well as of the 
transformation products.
    A highly efficient semi-analytical unsaturated zone transport 
module has been incorporated to handle the transport of metals in the 
unsaturated zone and can use MINTEQA2 derived linear or nonlinear 
sorption isotherms. Conventional numerical solution techniques are 
inadequate to handle extremely nonlinear isotherms. An enhanced method-
of-characteristic based solution has been implemented which overcomes 
these problems and thereby enables the simulation of metals transport 
in the probabilistic framework. Non-linearity in the metals sorption 
isotherms is primarily of concern at higher concentration values; for 
low concentrations, the isotherms are linear or close to linear. 
Because of the attenuation in the unsaturated zone, and the subsequent 
dilution in the saturated zone, concentrations in the saturated zone 
are usually low enough so that properly linearized isotherms are used 
by the model in the saturated zone without significant errors.
    The internal routines in the model which determine placement of the 
receptor well relative to the areal extent of the contaminant plume 
have been revised and enhanced to eliminate bias which was present in 
the implementation in the EPACML. The calculation of the areal extent 
of the plume has been revised to take into consideration the dimensions 
of the waste unit. The logic for placing a receptor well inside the 
plume limits has been improved to eliminate a bias towards larger waste 
unit areas and to ensure that the placement of the well inside these 
limits, for a given radial distance from the unit, is truly randomly 
uniform. However, for this proposal, the closest drinking water well is 
located anywhere on the downgradient side of the waste unit.
    The data sources from which parameter distributions for nationwide 
probabilistic assessments are obtained have been evaluated, and where 
appropriate, have been revised to make use of the latest data available 
for modeling. Leachate rates for Subtitle D waste units have been 
revised using the latest version of the Hydrologic Evaluation of 
Landfill Performance (HELP) model with the revised data inputs. Source 
specific input parameters (e.g., waste unit area and volume) have been 
developed for various different types of industrial waste units besides 
landfills. Input values for the groundwater related parameters have 
been revised to utilize information from a nationwide industry survey 
of actual contaminated sites. The original version of the model was 
implemented for probabilistic assessments assuming continuous source 
(infinite source) conditions only. This methodology did not take into 
account the finite volume and/or operational life of waste units. The 
EPACMTP model has been implemented for probabilistic assessments of 
either continuous source or finite source scenarios. In the latter 
scenario, predicted groundwater impact is not only based on the 
concentrations of contaminants in the leachate, but also on the amount 
of constituent in the waste unit and/or the operational life of the 
unit.
    The landfill is taken to be filled to capacity and covered when 
leaching begins. The time period during which the landfill is filled-
up, usually assumed to be 20 years, is considered to be small relative 
to the time required to leach all of the constituent mass out of the 
landfill. The model simulation results indicate that this assumption is 
not unreasonable; the model calculated leaching duration is typically 
several hundred years. The leachate flux, or infiltration rate, is 
determined using the HELP model. The net infiltration rate is 
calculated using a water balance approach, which considers 
precipitation, evapo-transpiration, and surface run-off. The HELP model 
was used to calculate landfill infiltration rates for a representative 
Subtitle D landfill with 2-foot earthen cover, and no liner or leachate 
collection system, using climatic data from 97 climatic stations 
located throughout the US. These correspond to the reasonable worst 
case assumptions as explained in the HWIR Risk Assessment Background 
Document for the HWIR proposed notice (60 FR 66344-December 21, 1995). 
Additional details on the methodologies used by the EPACMTP to derive 
DAFs for waste constituents modeled for the landfill scenario are 
presented in the Background Documents for the proposed HWIR docket (60 
FR 66344-December 21, 1995). The fraction of waste in the landfill is 
assigned a uniform distribution with lower and upper limits of 0.036 
and 1.0, respectively, based on analysis of waste composition in 
Subtitle D landfills. The lower bound assures that the waste unit will 
always contains a minimum amount of the waste of concern. The waste 
density is assigned a value based on reported densities of hazardous 
waste, and varies between 0.7 and 2.1 grams per cubic centimeter (g/
cm\3\.
    The area of the surface impoundment and the impoundment depth used 
by the EPACMTP are obtained from the OSW Subtitle D Industrial Survey 
and were entered into the probabilistic analyses as distributions. The 
sediment layer at the base of the impoundment is taken to be 2 feet 
thick, and have an effective equivalent saturated conductivity of 
10-7 centimeters per second (cm/s). These values were 
selected in recognition of the fact that most non-hazardous waste 
surface impoundments do have some kind of liners in place. Additional 
details on the methodologies used by the EPACMTP to derive DAFs for 
waste constituents modeled for the surface impoundment waste management 
scenario are presented in the Background Documents for the 1995 
proposed HWIR docket (60 FR 66344-December 21, 1995).
4. Has the EPACMTP Methodology Been Formally Reviewed?
    The Science Advisory Board (SAB), a public advisory group that 
provides information and advice to the EPA, reviewed the EPACMTP model 
as part of a continuing effort to provide improvements in the 
development and external peer review of environmental regulatory 
models. Overall, the SAB commended the Agency for making significant 
enhancements to the EPACMTP's predecessor (EPACML) and for responding 
to previous SAB suggestions. The SAB also concluded that the 
mathematical formulation incorporating transformation or degradation 
products into the model appeared to be correct and that the site-based 
approach using hydrogeologic regions is superior to the previous 
approach used in EPACML. The model underwent public comment during the 
1995 proposed HWIR (60 FR 66344-December 21, 1995).
5. Has the Agency Modified the EPACMTP as Utilized in the HWIR 
Proposal?
    The EPACMTP, as developed for HWIR, determined the DAF using a 
probabilistic approach that selected, at random, a waste volume from a 
range of waste volumes identified in EPA's 1987 Subtitle D landfill 
survey. In delisting determinations, the waste volume of the petitioner 
is known. Therefore, application of EPACMTP to the delisting program 
has been modified to evaluate the specific waste volume. The Agency 
modified the DAFs determined under the HWIR proposal to account for a 
known waste volume. To generate waste volume-specific DAFs, EPA

[[Page 58025]]

developed ``scaling factors'' to modify DAFs developed for HWIR (based 
on the entire range of disposal unit areas) to DAFs for delisting waste 
volumes. This was accomplished by computing a 90th percentile DAF for a 
conservative chemical for 10 specific waste volumes (ranging from 1,000 
cu. yds. to 300,000 cu. yds.) for each waste management scenario 
(landfill and surface impoundment). The Agency assumed that DAFs for a 
specific waste volume are linearly related to DAFs developed by EPACMTP 
for the HWIR. DAF scaling factors were computed for the ten increment 
waste volumes. Using these ten scaling factor DAFs, regression 
equations were developed for each waste management scenario to provide 
a continuum of DAF scaling factors as a function of waste volume.
    The regression equations are coded into the DRAS program which then 
automatically adjusts the DAF for the waste volume of the petitioner. 
The method used to verify the scaling factor approach is presented in 
Application of EPACMTP to Region 6 Delisting Program: Development of 
Volume-adjusted Dilution Attenuation Factors. For the landfill waste 
management scenario, the DAF scaling factors ranged from 9.5 for 10,000 
cu. yard to approximately 1.0 for waste volumes greater than 200,000 
cu. yards. Therefore, for solid waste volumes greater than 200,000 cu. 
yds., the waste volume-specific DAF is the same as the DAF computed for 
the proposed HWIR. The regression equation that can be used to 
determine the DAF scaling factor (DSF) as a function of waste volume 
(in cubic yards) for the landfill waste management unit is: DSF = 
6152.7 * (waste volume)--0.7135. The correlation coefficient of this 
regression equation is 0.99, indicating a good fit of this line to the 
data points. DAF scaling factors for surface impoundment waste volumes 
ranged from 2.4 for 2,000 cu. yards to approximately 1.0 for 100,000 
cu. yds. For liquid waste volumes greater than 200,000 cu. yds., the 
waste volume-specific DAF is the same as the DAF computed for the 
proposed HWIR. The regression equation for DSF as a function of waste 
volume for surface impoundment wastes is: DSF = 14.2 * (waste volume)--
0.2288. The correlation coefficient of this regression equation is also 
0.99, indicating an extremely good fit of this line to the data points.

V. Evaluation of This Petition

A. What Other Factors Did EPA Consider in Its Evaluation?

    We also consider the applicability of ground-water monitoring data 
during the evaluation of delisting petitions where the waste in 
question is or has ever been placed on land. In this case, a 
substantial record of groundwater analysis from monitoring wells in and 
around the existing landfill which contains the waste was available and 
submitted as part of the petition. Historical data showed elevated 
levels of hazardous constituents in the groundwater and indicated that 
the landfilled waste was a possible source. Additional groundwater 
analysis became available utilizing a more sophisticated EPA 
recommended sampling technique. The new data could not establish that 
hazardous substances were currently leaching from the landfill sludge 
at levels exceeding those predicted by the EPACMTP model in the DRAS 
program. The evaluation was based on a statistical analysis conducted 
in accordance with Statistical Analysis of Ground-Water Monitoring Data 
at RCRA Facilities--Interim Final Guidance, EPA, April 1989 and 
Statistical Analysis of Ground-Water Monitoring Data at RCRA 
Facilities--Addendum to Interim Final Guidance, EPA, July 1992. 
Leachate analysis of sludge samples generally supported the conclusion 
that the landfilled sludge was not currently a source of groundwater 
contamination above health-based levels.
    Specifically, the landfilled sludge did not appear to be leaching 
arsenic, cadmium, lead, or nickel to groundwater at this time. Cadmium 
and nickel in groundwater appear to be a concern at the facility, but 
the cadmium and nickel contamination could not be attributed to the 
landfilled sludge based only on the recent data. The landfilled sludge 
could be contributing chromium, zinc and/or thallium to the 
groundwater, but currently at levels below concern. The elevated 
thallium was detected in upgradient wells and all detections were very 
close to the detection levels. Based on most recent data, the 
landfilled sludge does not appear to currently leach hazardous 
constituents to groundwater at significantly different levels than 
predicted by leachate analysis and subsequent modeling (See Docket 
Report for Statistical Analysis of Recent Groundwater Analysis).

B. What Did EPA Conclude About USG's Analysis?

    The total cumulative risk posed by the waste, including the revised 
dioxin risk through fish ingestion is approximately 9.69  x  
10-6. EPA believes that this risk is acceptable because the 
value is within a generally acceptable range of 1  x  10-4 
to 1  x  10 -6 and a large portion of the estimated risk is 
associated with a single contaminant/pathway which may be evaluated in 
more than one way. Specifically, ingestion of carcinogenic arsenic in 
groundwater contributes 8.39  x  10-6, or 86.5% of the total 
risk. Total arsenic levels in the landfilled waste were not 
statistically different than arsenic levels in soils not associated 
with the landfill and recent ground-water monitoring at the facility 
did not detect arsenic at a detection level of 0.005 milligrams per 
liter (mg/L). Furthermore, if the POE target concentration was set at 
the Safe Drinking Water Act (SWDA) Maximum Contaminant Level (MCL), the 
maximum allowable waste leachate concentration would be 7.09 mg/L TCLP 
arsenic, over 100 times higher than the maximum observed leachate 
concentration in the waste. EPA's July 1996 Soil Screening Guidance: 
User's Guide, EPA/540/R-96/018, states that acceptable levels of 
contaminants in soils for the ground-water pathway should be derived 
from SWDA Maximum Contaminant Level Goals (MCLG) or MCLs. Health-based 
limits as used in the DRAS program can be used if MCLs are not 
available. Given that the difference between the MCL for arsenic and 
the health-based POE concentration is three orders of magnitude, we 
believe that some allowance can be exercised in setting the allowable 
level for arsenic in the leachate. EPA proposes to set the allowable 
arsenic leachate level at a concentration which corresponds to a total 
waste cancer risk of 1  x  10-4 which is still within the 
generally acceptable range of 1  x  10-4 to 1  x  
10-6. Delisting levels for constituents other than arsenic 
will still be set at concentrations corresponding to the original 
Region 5 target of 1  x  10-6. By this method, the delisting 
level for leachable arsenic in this proposed exclusion will be set at a 
value which corresponds to a POE concentration of approximately one 
tenth of the existing MCL. The EPA has recently proposed to lower the 
arsenic MCL to one tenth its current value and thus, if finalized, 
would correspond well with the delisting level we are setting.
    After reviewing USG's processes, the EPA concludes that (1) 
hazardous constituents of concern are present in USG's waste, but not 
at levels which are likely to pose a threat to human health and the 
environment when placed in a solid waste landfill; and (2) the 
petitioned waste does not exhibit any of the characteristics of 
ignitability, corrosivity, or reactivity. See 40 CFR 261.21, 261.22, 
and 261.23, respectively.

[[Page 58026]]

C. What is EPA's Final Evaluation of This Delisting Petition?

    The descriptions of the USG hazardous waste process and analytical 
characterization, with the proposed verification testing requirements 
(as discussed later in this document, provide a reasonable basis for 
EPA to grant the exclusion.
    We have reviewed the sampling procedures used by USG and have 
determined they satisfy EPA criteria for collecting representative 
samples of constituent concentrations in the wastewater treatment 
sludge.
    We believe the data submitted in support of the petition show that 
USG's waste will not pose a threat when disposed of in a Subtitle D 
landfill regulated by a state. We therefore, propose to grant USG an 
exclusion for its WWTP sludge.
    If we finalize the proposed rule, the Agency will no longer 
regulate the petitioned waste under 40 CFR Parts 262 through 268 and 
the permitting standards of Part 270.

VI. Conditions for Exclusion

A. What Are the Maximum Allowable Concentrations of Hazardous 
Constituents in the Waste?

    The following table summarizes maximum observed total and TCLP 
concentrations in USG's waste, maximum allowable leachate levels for 
USG's waste, and the level of regulatory concern at the point of 
exposure for groundwater. The EPA calculated delisting levels for most 
constituents detected.
    Maximum allowable leachate concentrations (expressed as a result of 
the TCLP test) were calculated for all constituents for which leachate 
was analyzed. Most of the allowable leachate concentrations were 
derived from the health-based calculation within the DRAS program. The 
remaining maximum allowable leachate levels were derived from MCLs, 
SDWA Treatment Technique (TT) action levels, or toxicity characteristic 
levels from 40 CFR 261.24 if they resulted in a more conservative 
delisting level. The singular exception is arsenic which was discussed 
in section V.B. The maximum allowable point of exposure groundwater 
concentrations correspond to the lesser of the health-based values 
calculated within the DRAS program or the MCLs or TT action levels. 
MCLs were used for maximum point of exposure groundwater concentrations 
for constituents which were not analyzed for in leachate extracts.
    A statistical review of some of the data indicates that the maximum 
values used in the modeling and risk estimation correspond to a very 
high confidence interval (See Docket Report on Degree of 
Characterization of Existing Landfilled Sludge at the American Metals 
Corporation Facility, Westlake, Ohio). Assuming that the distribution 
of the data is adequately defined, future samples are likely to exhibit 
concentrations which are less than the maximum values used in this 
evaluation. All of the maximum waste concentrations observed are less 
than the corresponding delisting levels assigned. The maximum observed 
concentration of PCBs was close to the delisting level. However, PCBs 
were not detected in most samples.

----------------------------------------------------------------------------------------------------------------
                                         Maximum \1\        Maximum \1\     Maximum allowable  Maximum allowable
                                        observed total   observed leachate       leachate      point of exposure
             Constituent              concentration (mg/ concentration (mg/ concentration (mg/ concentration (mg/
                                             kg)              L TCLP)            L TCLP)       L in groundwater)
----------------------------------------------------------------------------------------------------------------
                                             Inorganic Constituents
----------------------------------------------------------------------------------------------------------------
Antimony............................          1.2                0.023          \2\ 1.52           \2\ 0.006
Arsenic.............................         19.0                0.058              0.691              0.005
Barium..............................        120                  0.215        \3\ 100              \2\ 2.0
Beryllium...........................          0.86               0.003          \2\ 3.07           \2\ 0.004
Cadmium.............................          2.8                0.013          \3\ 1.0            \2\ 0.005
Chromium (total)....................       3660                  0.277          \3\ 5.0            \2\ 0.1
Chromium (hexavalent)...............          0.60              NR                 NA              \2\ 0.1
Cobalt..............................        142                  0.223            166                  2.25
Copper..............................         31.9                0.010      \2\ 67,300             \2\ 1.3
Lead................................        130                  0.036          \3\ 5              \2\ 0.015
Mercury.............................          0.23               0.012          \3\ 0.2            \2\ 0.002
Nickel..............................         76.9                0.128            209                  0.75
Selenium............................          5.1                0.053          \3\ 1              \2\ 0.05
Silver..............................          0.5                0.018          \3\ 5              \2\ 0.188
Thallium............................          1.5                0.002          \2\ 0.65           \2\ 0.002
Tin.................................         12.1                0.025          1,660                 22.46
Vanadium............................         75.5                0.014            156                  0.263
Zinc................................     104000                 70.9            2,070                 11.25
Cyanide (total).....................          1.0               NR                 NA              \2\ 0.2
Cyanide (amenable)..................         NA                 NR                 NA                 NA
----------------------------------------------------------------------------------------------------------------
                                              Organic Constituents
----------------------------------------------------------------------------------------------------------------
Acetone.............................          0.16              NR                 NA                 NA
Benzene.............................          0.009              0.025              0.089              0.00067
Bis(2-ethylhexyl) phthalate.........          1.6               NR                 NA              \2\ 0.006
Fluoranthene........................          0.2               NR                 NA                 NA
Methyl ethyl ketone.................          0.071              0.250        \3\ 200                 22.57
Methylene chloride..................          0.019             NR                 NA              \2\ 0.005
Phenanthrene........................          0.17               0.010             NA                 NA
Polychlorinated biphenyls...........          0.22              NR                 NA              \2\ 0.0005
Pyrene..............................          0.29               0.010              9.12               0.065
Tetrachlorethylene..................          0.034              0.025              0.197              0.0014
Xylenes.............................          0.051             NR                 NA             \2\ 10
----------------------------------------------------------------------------------------------------------------

[[Page 58027]]

 
                                               Dioxins and furans
----------------------------------------------------------------------------------------------------------------
2,3,7,8-TCDD........................          0.000008          NR                 NA                 NA
1,2,3,7,8-PeCDD.....................          0.0000026         NR                 NA                 NA
1,2,3,4,7,8-HxCDD...................          0.0000052         NR                 NA                 NA
1,2,3,6,7,8-HxCDD...................          0.0000074         NR                 NA                 NA
1,2,3,7,8,9-HxCDD...................          0.000011          NR                 NA                 NA
1,2,3,4,6,7,8-HpCDD.................          0.00109           NR                 NA                 NA
OCDD................................          0.159             NR                 NA                 NA
2,3,7,8-TCDF........................          0.0000017         NR                 NA                 NA
1,2,3,7,8-PeCDF.....................          0.0000082         NR                 NA                 NA
2,3,4,7,8-PeCDF.....................          0.000088          NR                 NA                 NA
1,2,3,4,7,8-HxCDF...................          0.0000086         NR                 NA                 NA
1,2,3,6,7,8-HxCDF...................          0.0000074         NR                 NA                 NA
2,3,4,6,7,8-HxCDF...................          0.0000086         NR                 NA                 NA
1,2,3,7,8,9-HxCDF...................          0.0000097         NR                 NA                 NA
1,2,3,4,6,7,8-HpCDF.................          0.0000062         NR                 NA                 NA
1,2,3,4,7,8,9-HpCDF.................          0.000013          NR                 NA                 NA
OCDF................................          0.000052          NR                 NA                 NA
2,3,7,8-TCDD TEQ\4\.................          0.000182          NR                 NA                NA
----------------------------------------------------------------------------------------------------------------
\1\ These levels represent the highest constituent concentration found in any one sample, not necessarily the
  specific levels found in one sample.
\2\ The concentration is based on the MCL or TT action level.
\3\ The concentration is based on the toxicity characteristic level in 40 CFR 261.24.
\4\ Concentrations of individual dioxin and furan congeners in a given sample were combined into a single
  concentration representing the equivalent concentration of 2,3,7,8-TCDD based on toxicity.
 The constituent was not detected at the stated concentration.
NA Not Applicable.
NR Analysis not run.

    In addition to the delisting values in the table, several delisting 
levels based on total concentrations were also established for USG's 
waste. Total arsenic is limited to 9,280 mg/kg. Total mercury is 
limited to 94 mg/kg. Total PCBs are limited to 0.265 mg/kg. Since all 
of the dioxin and furan congeners exhibit a toxicity which can be 
related to 2,3,7,8-TCDD, delisting levels were not calculated for each 
congener. Since the dioxin and furan congeners also bioaccumulate at 
different rates than 2,3,7,8-TCDD, the cumulative risk varies among all 
dioxin and furan congeners. The Docket Report on Evaluation of 
Contaminant Releases to Surface Water Resulting from American Metal's 
Petitioned Waste contains congener specific factors which, when 
multiplied by the congener concentration in the waste, provides the 
individual risk posed by each congener. These risks were summed and 
compared to the target risk level of 1 x 10-6. None of the 
samples analyzed for dioxins and furans exceeded the target level. The 
congener-specific factors for the combined 2,3,7,8-TCDD delisting level 
are as follows:

2,3,7,8-TCDD--3.8 x 10-2;
1,2,3,7,8-PeCDD--1.8 x 10-2;
1,2,3,4,7,8-HxCDD--1.2 x 10-3;
1,2,3,6,7,8-HxCDD--4.9 x 10-4;
1,2,3,7,8,9-HxCDD--5.43 x 10-4
1,2,3,4,6,7,8-HpCDD--2.09 x 10-5;
OCDD--5 x 10-7;
2,3,7,8-TCDF--2.72 x 10-3;
1,2,3,7,8-PeCDF--4.17 x 10-4;
2,3,4,7,8-PeCDF--3.04 x 10-2;
1,2,3,4,7,8-HxCDF--2.99 x 10-4;
1,2,3,6,7,8-HxCDF--7.33 x 10-4;
2,3,4,6,7,8-HxCDF--2.46 x 10-3;
1,2,3,7,8,9-HxCDF--2.66 x 10-3;
1,2,3,4,6,7,8-HpCDF--4.38 x 10-6;
1,2,3,4,7,8,9-HpCDF--1.55 x 10-4; and
OCDF--6.7 x 10-7.

    The sum of the products of dioxin and furan congener concentrations 
(mg/kg) and these factors may not exceed 1 x 10-\6\.

B. What Are the Conditions of the Exclusion?

    The proposed exclusion only applies to the 12,400 cubic yards of 
landfilled sludge described in the petition. Any amount exceeding this 
volume cannot be considered delisted under this exclusion. Furthermore, 
USG must dispose of this sludge in a Subtitle D landfill which is 
permitted, licensed, or registered by a state to manage industrial 
waste.
    USG must also complete additional verification sampling in order to 
ensure that the landfilled sludge meets delisting requirements. The 
Docket Report on Degree of Characterization of Existing Landfilled 
Sludge at the American Metals Corporation Facility, Westlake, Ohio 
describes additional characterization of the landfilled sludge needed 
to provide a more adequate delineation of the spatial distribution of 
constituents of concern in the landfilled sludge. The verification 
sampling was evaluated based on the total number of samples taken thus 
far, their location, and the importance of the analytes based on risk. 
Composite samples comprising the vertical extent of the landfilled 
sludge at each individual boring location are to be collected from six 
different boring locations within the landfilled sludge areas. The 
samples are to be analyzed for TCLP metals including antimony, arsenic, 
barium, beryllium, cadmium, chromium, lead, mercury, nickel, selenium, 
silver, thallium, tin, vanadium, and zinc. Five of the borings are to 
be located within the larger of the two landfilled sludge deposits and 
placed in a manner that compliments the existing seven samples 
identified as WD-1 through WD-4 and LB1 through LB3. The remaining 
verification sample must be collected from a single boring placed 
within the smaller of the two landfilled sludge deposits.
    If, anytime after disposal of the delisted waste, USG possesses or 
is otherwise made aware of any environmental or waste data (including 
but not limited to leachate data or groundwater monitoring data) or any 
other data relevant to the delisted waste indicating that any 
constituent identified in Section VI.A. is at a level

[[Page 58028]]

higher than the delisting level established in Section VI.A. or is at a 
level in groundwater that exceeds the point of exposure concentration 
established in Section VI.A., then USG must report such data, in 
writing, to the Regional Administrator within 10 days of first 
possessing or being made aware of that data.
    Based on any information provided by USG and any other information 
received from any source, the Regional Administrator will make a 
preliminary determination as to whether the reported information 
requires Agency action to protect human health or the environment. 
Further action may include suspending, or revoking the exclusion, or 
other appropriate response necessary to protect human health and the 
environment.

C. What Happens if USG Fails To Meet the Conditions of the Exclusion?

    If USG violates the terms and conditions established in the 
exclusion, the Agency may start procedures to withdraw the exclusion.
    The EPA has the authority under RCRA and the Administrative 
Procedures Act, 5 U.S.C. 551 (1978) et seq. (APA), to reopen a 
delisting decision if we receive new information indicating that the 
conditions of this exclusion have been violated.
    If the Regional Administrator determines that information reported 
by USG as described in Section VI.B., or information received from any 
other source, does require Agency action, the Regional Administrator 
will notify USG in writing of the actions the Regional Administrator 
believes are necessary to protect human health and the environment. The 
notice shall include a statement of the proposed action and a statement 
providing USG with an opportunity to present information as to why the 
proposed Agency action is not necessary or to suggest an alternative 
action. USG shall have 10 days from the date of the Regional 
Administrator's notice to present the information.
    If after 10 days, USG presents no further information, the Regional 
Administrator will issue a final written determination describing the 
Agency actions that are necessary to protect human health or the 
environment. Any required action described in the Regional 
Administrator's determination shall become effective immediately, 
unless the Regional Administrator provides otherwise.

VII. Regulatory Impact

    Under Executive Order 12866, EPA must conduct an ``assessment of 
the potential costs and benefits'' for all ``significant'' regulatory 
actions.
    The proposal to grant an exclusion is not significant, since its 
effect, if promulgated, would be to reduce the overall costs and 
economic impact of EPA's hazardous waste management regulations. This 
reduction would be achieved by excluding waste generated at a specific 
facility from EPA's lists of hazardous wastes, thus enabling a facility 
to manage its waste as nonhazardous.
    Because there is no additional impact from today's proposed rule, 
this proposal would not be a significant regulation, and no cost/
benefit assessment is required. The Office of Management and Budget 
(OMB) has also exempted this rule from the requirement for OMB review 
under Section (6) of Executive Order 12866.

VIII. Regulatory Flexibility Act

    Under the Regulatory Flexibility Act, 5 U.S.C. 601-612, whenever an 
agency is required to publish a general notice of rulemaking for any 
proposed or final rule, it must prepare and make available for public 
comment a regulatory flexibility analysis which describes the impact of 
the rule on small entities (that is, small businesses, small 
organizations, and small governmental jurisdictions). No regulatory 
flexibility analysis is required, however, if the Administrator or 
delegated representative certifies that the rule will not have any 
impact on small entities.
    This rule, if promulgated, will not have an adverse economic impact 
on small entities since its effect would be to reduce the overall costs 
of EPA's hazardous waste regulations and would be limited to one 
facility. Accordingly, the Agency certifies that this proposed 
regulation, if promulgated, will not have a significant economic impact 
on a substantial number of small entities. This regulation, therefore, 
does not require a regulatory flexibility analysis.

IX. Paperwork Reduction Act

    Information collection and record-keeping requirements associated 
with this proposed rule have been approved by OMB under the provisions 
of the Paperwork Reduction Act of 1980 (Public Law 96-511, 44 U.S.C. 
3501 et seq.) and have been assigned OMB Control Number 2050-0053.

X. Unfunded Mandates Reform Act

    Under section 202 of the Unfunded Mandates Reform Act of 1995 
(UMRA), P.L. 104-4, which was signed into law on March 22, 1995, EPA 
generally must prepare a written statement for rules with federal 
mandates that may result in estimated costs to state, local, and tribal 
governments in the aggregate, or to the private sector, of $100 million 
or more in any one year.
    When such a statement is required for EPA rules, under section 205 
of the UMRA, EPA must identify and consider alternatives, including the 
least costly, most cost-effective, or least burdensome alternative that 
achieves the objectives of the rule. EPA must select that alternative, 
unless the Administrator explains in the final rule why it was not 
selected or it is inconsistent with law.
    Before EPA establishes regulatory requirements that may 
significantly or uniquely affect small governments, including tribal 
governments, EPA must develop under section 203 of the UMRA a small 
government agency plan. The plan must provide for notifying potentially 
affected small governments, giving them meaningful and timely input in 
the development of EPA regulatory proposals with significant federal 
intergovernmental mandates, and informing, educating, and advising them 
on compliance with the regulatory requirements.
    The UMRA generally defines a federal mandate for regulatory 
purposes as one that imposes an enforceable duty upon state, local, or 
tribal governments or the private sector.
    The EPA finds that today's delisting decision is deregulatory in 
nature and does not impose any enforceable duty on any state, local, or 
tribal governments or the private sector. In addition, the proposed 
delisting decision does not establish any regulatory requirements for 
small governments and so does not require a small government agency 
plan under UMRA section 203.

XI. Executive Order 12875

    Under Executive Order 12875, EPA may not issue a regulation that is 
not required by statute and that creates a mandate upon a state, local, 
or tribal government, unless the federal government provides the funds 
necessary to pay the direct compliance costs incurred by those 
governments. If the mandate is unfunded, EPA must provide to OMB a 
description of the extent of EPA's prior consultation with 
representatives of affected state, local, and tribal governments; the 
nature of their concerns; copies of written communications from the 
governments; and a statement supporting the need to issue the 
regulation. In addition, Executive Order 12875 requires EPA to develop 
an effective process permitting elected officials and other 
representatives of state, local, and tribal governments ``to provide 
meaningful and timely input in the development of

[[Page 58029]]

regulatory proposals containing significant unfunded mandates.'' 
Today's rule does not create a mandate on state, local or tribal 
governments. The rule does not impose any enforceable duties on these 
entities. Accordingly, the requirements of section 1(a) of Executive 
Order 12875 do not apply to this rule.

XII. Executive Order 13045

    Executive Order 13045 is entitled ``Protection of Children from 
Environmental Health Risks and Safety Risks'' (62 FR 19885, April 23, 
1997). This order applies to any rule that EPA determines (1) is 
economically significant as defined under Executive Order 12866, and 
(2) the environmental health or safety risk addressed by the rule has a 
disproportionate effect on children. If the regulatory action meets 
both criteria, the Agency must evaluate the environmental health or 
safety effects of the planned rule on children, and explain why the 
planned regulation is preferable to other potentially effective and 
reasonably feasible alternatives considered by the Agency. This 
proposed rule is not subject to Executive Order 13045 because this is 
not an economically significant regulatory action as defined by 
Executive Order 12866.

XIII. Executive Order 13084

    Under Executive Order 13084, EPA may not issue a regulation that is 
not required by statute, that significantly affects or uniquely affects 
that communities of Indian tribal governments, and that imposes 
substantial direct compliance costs on those communities, unless the 
federal government provides the funds necessary to pay the direct 
compliance costs incurred by the tribal governments.
    If the mandate is unfunded, EPA must provide to OMB, in a 
separately identified section of the preamble to the rule, a 
description of the extent of EPA's prior consultation with 
representatives of affected tribal governments, a summary of the nature 
of their concerns, and a statement supporting the need to issue the 
regulation.
    In addition, Executive Order 13084 requires EPA to develop an 
effective process permitting elected and other representatives of 
Indian tribal governments ``to meaningful and timely input'' in the 
development of regulatory policies on matters that significantly or 
uniquely affect their communities of Indian tribal governments. This 
action does not involve or impose any requirements that affect Indian 
Tribes. Accordingly, the requirements of section 3(b) of Executive 
Order 13084 do not apply to this rule.

XIV. National Technology Transfer and Advancement Act

    Under Section 12(d) of the National Technology Transfer and 
Advancement Act, the Agency is directed to use voluntary consensus 
standards in its regulatory activities unless doing so would be 
inconsistent with applicable law or otherwise impractical.
    Voluntary consensus standards are technical standards (for example, 
materials specifications, test methods, sampling procedures, business 
practices, etc.) that are developed or adopted by voluntary consensus 
standard bodies. Where EPA does not use available and potentially 
applicable voluntary consensus standards, the Act requires that Agency 
to provide Congress, through the OMB, an explanation of the reasons for 
not using such standards.
    This rule does not establish any new technical standards, and thus 
the Agency has no need to consider the use of voluntary consensus 
standards in developing this proposed rule.

List of Subjects in 40 CFR Part 261

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

    Authority: Sec. 3001(f) RCRA, 42 U.S.C. 6921(f).

    Dated: September 19, 2000.
Joseph M. Boyle,
Acting Director, Waste, Pesticides and Toxics Division.

    For the reasons set out in the preamble, 40 CFR Part 261 is 
proposed to be amended as follows:

PART 261--IDENTIFICATION AND LISTING OF HAZARDOUS WASTE

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

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

    2. In Table 1 of Appendix IX of Part 261 it is proposed to add the 
following waste stream in alphabetical order by facility to read as 
follows:

[[Page 58030]]

Appendix IX to Part 261--Wastes Excluded Under Secs. 260.20 and 
260.22

                               Table 1--Wastes Excluded From Non-Specific Sources
----------------------------------------------------------------------------------------------------------------
              Facility                         Address                           Waste description
----------------------------------------------------------------------------------------------------------------
 
*                  *                  *                  *                  *                  *
                                                        *
American Metals Corporation........  Westlake, Ohio.............  Wastewater treatment plant (WWTP) sludges from
                                                                   the chemical conversion coating (phosphating)
                                                                   of aluminum (EPA Hazardous Waste No. F019)
                                                                   and other solid wastes previously disposed in
                                                                   an on-site landfill. This is a one-time
                                                                   exclusion for 12,400 cubic yards of
                                                                   landfilled WWTP sludge. This exclusion was
                                                                   published on (insert publication date of the
                                                                   final rule).
                                                                  1. Delisting Levels:
                                                                  (A) The constituent concentrations measured in
                                                                   the TCLP extract may not exceed the following
                                                                   levels (mg/L): antimony--1.52; arsenic--
                                                                   0.691; barium--100; beryllium--3.07; cadmium--
                                                                   1; chromium--5.0; cobalt--166; copper--
                                                                   67,300; lead--5; mercury--0.2; nickel--209;
                                                                   selenium--1; silver--5; thallium--0.65; tin--
                                                                   1,660; vanadium--156; and zinc--2,070.
                                                                  (B) The total constituent concentrations in
                                                                   any sample may not exceed the following
                                                                   levels (mg/kg): arsenic--9,280; mercury--94;
                                                                   and polychlorinated biphenyls--0.265.
                                                                  (C) The sum of the products of dioxin and
                                                                   furan congener concentrations (mg/kg) and the
                                                                   factors defined in Section VI. A. of the
                                                                   preamble may not exceed 1 x 10-\6\.
                                                                  2. Verification Sampling--Composite samples
                                                                   comprising the vertical extent of the
                                                                   landfilled sludge at individual boring
                                                                   locations are to be collected from six
                                                                   different boring locations within the
                                                                   landfilled sludge areas. The samples are to
                                                                   be analyzed for TCLP metals including
                                                                   antimony, arsenic, barium, beryllium,
                                                                   cadmium, chromium, lead, mercury, nickel,
                                                                   selenium, silver, thallium, tin, vanadium,
                                                                   and zinc. Five of the borings are to be
                                                                   located within the larger of the two
                                                                   landfilled sludge deposits and placed in a
                                                                   manner that compliments the existing seven
                                                                   samples identified as WD-1 through WD-4 and
                                                                   LB1 through LB3. The remaining verification
                                                                   sample must be collected from a single boring
                                                                   placed within the smaller of the two
                                                                   landfilled sludge deposits. The results are
                                                                   to be compared to the delisting levels in
                                                                   Condition (1)(a). Sludge from which samples
                                                                   collected exceed delisting levels are not
                                                                   delisted. Additional sampling can be
                                                                   conducted with the approval of U.S. EPA
                                                                   Region 5 in order to isolate the sludge which
                                                                   exceeds the delisting levels from sludge that
                                                                   meets the delisting levels.

[[Page 58031]]

 
                                                                  3. Reopener Language--
                                                                  (a) If, anytime after disposal of the delisted
                                                                   waste, USG possesses or is otherwise made
                                                                   aware of any data (including but not limited
                                                                   to leachate data or groundwater monitoring
                                                                   data) or any other data relevant to the
                                                                   delisted waste indicating that any
                                                                   constituent identified in Condition (1) is at
                                                                   a level higher than the delisting level
                                                                   established in Condition (1), or is at a
                                                                   level in the groundwater at a level exceeding
                                                                   the point of exposure groundwater levels
                                                                   established in Section VI.A. of the preamble,
                                                                   then USG must report such data, in writing,
                                                                   to the Regional Administrator within 10 days
                                                                   of first possessing or being made aware of
                                                                   that data.
                                                                  (b) Based on the information described in
                                                                   paragraph (a) and any other information
                                                                   received from any source, the Regional
                                                                   Administrator will make a preliminary
                                                                   determination as to whether the reported
                                                                   information requires Agency action to protect
                                                                   human health or the environment. Further
                                                                   action may include suspending, or revoking
                                                                   the exclusion, or other appropriate response
                                                                   necessary to protect human health and the
                                                                   environment.
                                                                  (c) If the Regional Administrator determines
                                                                   that the reported information does require
                                                                   Agency action, the Regional Administrator
                                                                   will notify USG in writing of the actions the
                                                                   Regional Administrator believes are necessary
                                                                   to protect human health and the environment.
                                                                   The notice shall include a statement of the
                                                                   proposed action and a statement providing USG
                                                                   with an opportunity to present information as
                                                                   to why the proposed Agency action is not
                                                                   necessary or to suggest an alternative
                                                                   action. USG shall have 10 days from the date
                                                                   of the Regional Administrator's notice to
                                                                   present the information.
                                                                  (d) If after 10 days USG presents no further
                                                                   information, the Regional Administrator will
                                                                   issue a final written determination
                                                                   describing the Agency actions that are
                                                                   necessary to protect human health or the
                                                                   environment. Any required action described in
                                                                   the Regional Administrator's determination
                                                                   shall become effective immediately, unless
                                                                   the Regional Administrator provides
                                                                   otherwise.
                                                                  3. Notifications--USG must provide a one-time
                                                                   written notification to any State Regulatory
                                                                   Agency to which or through which the waste
                                                                   described above will be transported for
                                                                   disposal at least 60 days prior to the
                                                                   commencement of such activities. Failure to
                                                                   provide such a notification will result in a
                                                                   violation of the delisting petition and a
                                                                   possible revocation of the decision.
 
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[FR Doc. 00-24790 Filed 9-26-00; 8:45 am]
BILLING CODE 6560-50-U
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