NOTICE OF DATA AVAILABILITY (NODA)

 RESPONSE TO COMMENT DOCUMENT


 PART I



 June 1998
























 
 U.S. Environmental Protection Agency
 Office of Solid Waste, OSW (Note: Office of Solid Waste, OSW, was renamed Office of Resource Conservation and Recovery, ORCR, on January 18, 2009)
 401 M Street, SW
 Washington, DC 20460

 TABLE OF CONTENTS


General Comments . . . . . . . . . . . . . . . . . . . . 0-1

I. Additional Information. . . . . . . . . . . . . . . I-1
 A. Supplemental Background Document: Groundwater
 Pathway Risk Analysis: Petroleum Refining Process
 Waste Listing Determination. . . . . . . . . . I-2
 1. Revised High End Analysis . . . . . . . . I-8
 2. Monte Carlo Analysis. . . . . . . . . . . I-9
 3. Co-disposal . . . . . . . . . . . . . . .I-15
 4. Capping Waste Analysis Results at TC LevelsI-25
 5. Waste-Specific Comments . . . . . . . . .I-32
 6. Other Groundwater Modeling Issues . . . .I-48
 a. Distance to Well . . . . . . . . . .I-48
 b. Active Life. . . . . . . . . . . . .I-54
 c. Landfill Size. . . . . . . . . . . .I-60
 d. Biodegradation . . . . . . . . . . .I-66
 e. Plume Centerline . . . . . . . . . .I-69
 f. Dispersivity . . . . . . . . . . . .I-72
 g. Existing Groundwater Contamination .I-73
 B. Supplemental Background Document: Non-groundwater
 Pathway Risk Analysis: Petroleum Refining Process
 Waste Listing Determination. . . . . . . . . .I-81
 1. Eliminating Wastes Managed as Hazardous .I-84
 2. Model Modifications Regarding Release and
 Transport of Soil to Off-site Receptors .I-85
 3. Co-disposal . . . . . . . . . . . . . . .I-96
 C. Supplemental Background Document: Listing Support
 Analyses: Petroleum Refining Process Waste Listing
 Determination. . . . . . . . . . . . . . . . .I-99
 1. Analyses Regarding Leaching of Oily WasteI-99
 2. Potential for Additive Risks from Multiple
 Sources . . . . . . . . . . . . . . . . I-155
General Comments

Comment 1: The National Petroleum Refiners Association
(NPRA) supports EPA's decision which is based on both the
initial and new data analyses not to list eleven of the
fourteen residuals identified in this rulemaking. However,
NPRA does not believe that the new data analyses demonstrate
that the risks from the CSO sediment, hydrotreating
catalysts, and hydrorefining catalysts warrant their listing
as RCRA hazardous wastes. EPA overstated the potential risks
because of errors in the methodology used to determine the
risks as described below (NPRA, 00004, pg 1):

a) EPA's Monte Carlo analysis conducted with the new data
 supports a no-listing decision for Hydrotreating and
 Hydrorefining Catalyst . The Monte Carlo analysis is
 recognized by EPA as a superior technical approach to
 the deterministic approach which EPA used to make the
 listing determination. EPA should use results of the
 Monte Carlo risk analysis as basis for the listing
 decision. The deterministic analysis, on the other
 hand, does not allow EPA to determine what percentile
 of the risk distribution is represented by the high-end
 analysis. This information is necessary to make a
 defensible listing decision.

b) EPA failed to follow its own policy decision by using
 the OSW database to determine the distance between
 landfills and groundwater wells. EPA previously stated
 that existing data such as the OSW database was not
 acceptable because it was too general and was not
 specific enough for the refining sector which is the
 focus of this rulemaking. As EPA stated at the start
 of this rulemaking, the OSW database is not refinery
 specific. On the other hand, the Section 3007 survey
 is specific to this rulemaking. 

Response: (a) The Agency agrees with the commenter that the
Monte Carlo approach allows the EPA to determine the
percentile of the risk distribution represented by the two
high-end analysis. However, both the two high-end parameter
and the Monte Carlo analyses show risk above the
discretionary range for waste streams proposed to be listed
based on the groundwater pathway analysis (see Table 5.7 in
the Additional Groundwater Pathway Risk Analysis,
Supplemental Background Document, USEPA, 1998; risks for
benzene and arsenic in hydrotreating catalyst and
hydrorefining catalyst and for benzene in crude oil tank
sediment are all above 1E-05). 
(b) For responses to comments in paragraph (b), see
discussion in Section I.A.6.a.

Comment 2: Comments on Notice of Data Availability

NPRA comments on March 14, 1996 supported EPA's original
proposal not to list eleven residuals: sludge from sulfuric
acid alkylation; catalyst from sulfuric acid alkylation;
Claus and Scot-like catalyst; catalyst from catalytic
reforming; catalyst and fines from catalytic cracking; crude
oil storage tank sludge; sludge from sulfur complex and H2S
removal facilities; spent caustic from liquid treating;
unleaded gasoline storage tank sediment; off-specification
product and fines from thermal processes; and sludge from HF
alkylation. EPA's original proposal was supported by sound
data and a conservative risk assessment.

The new analysis conducted by EPA and provided in the NODA
does not demonstrate any reason to change EPA's original
decision. In fact, the results of the Monte Carlo risk
analysis strengthen EPA's decision not to list these eleven
residuals even considering co-disposal. Further, the new
analysis on additive risks did not identify any conditions
where individuals would be simultaneously exposed to
residuals being managed in a landfill or land treatment
unit. (NPRA, 0004)

Response: The Agency appreciates the commenter's supportive
comments. The Agency has conducted additional analyses that
are presented in the Additional Groundwater Pathway
Supplemental Background Document. The final decisions are
based on those results as discussed in the preamble to the
final rule.

For waste-specific comment responses, see Section I.A.5. 
For co-disposal responses, see Section I.A.3. For additive
risk responses, see Section I.C.2 of this Response to
Comment Document and Section III.R of the Proposed Rule
Response to Comment Document.

Comment 3: EPA Has Ample Support for its Proposal That
Eleven of the Fourteen Refinery Residuals Considered for
Listing Do Not Warrant Listing

As part of the NODA, EPA conducted several new analyses,
including evaluation of co-disposal and additive risk
scenarios. EPA's proposal not to list sludge from sulfuric
acid alkylation, catalyst from sulfuric acid alkylation,
crude oil storage tank sludge, Claus catalyst and SCOT-like
catalyst, catalyst from catalytic reforming, catalyst and
fines from catalytic cracking, sludge from sulfur complex
and H2S removal facilities, spent caustic from liquid
treating, unleaded gasoline storage tank sediment, off-
specification product and fines from thermal processes, and
sludge from HF alkylation is adequately supported by these
new analyses as well as the original listing proposal. As
discussed in API's comments of March 21, 1996, EPA's
proposal not to list these eleven residuals is supported by
sound data and a conservative, iterative risk assessment
process. Additionally, as discussed in API's March 1996
comments, some of these residuals are often used in such a
manner that they are not solid wastes and, therefore, are
not appropriate candidates for listing. 

The new analyses clearly support EPA's no list decision for
the eleven residuals listed above. In the case of additive
risks, EPA could find no circumstance which would suggest
that individuals would be simultaneously exposed to
residuals managed in an on-site landfill or land treatment
unit. Similarly, for co-disposal, EPA's analysis emphasizes
the fact that these eleven residuals do not warrant listing,
even with great conservatism in the risk assessment. EPA's
Monte Carlo analysis strengthens these results and further
highlights the conservatism in EPA's risk assessment for
both the high-end analysis and the co-disposal scenario. In
fact, the Monte Carlo analysis illustrates that the risks
predicted by the high-end analysis clearly fall at levels
greater than the 95th percentile.

In summary, EPA's analyses do not demonstrate that these
eleven residuals pose a substantial hazard to human health
and environment as required for listing by the 261.11(a)(3)
listing criteria. (API, 00009)

Response: The Agency acknowledges the commenter's
supportive comments. However, EPA has decided to list crude
oil storage tank sediment as discussed in the preamble to
the final rule.

For waste-specific comment responses, see Section I.A.5. 
For co-disposal responses, see Section I.A.3. 

Comment 4: EPA Should Not List Any of the Refining
Residuals Proposed for Listing

As detailed in API's comments on the flaws and errors
contained in the revised NODA risk assessments, and in
Mobil's and API's comments on the original November 20, 1995
proposal, EPA has failed to properly acknowledge and weigh
the existing regulatory protections provided by the Toxicity
Characteristic rule and other federal transportation
regulations, and continues to rely on flawed risk
assessments that overstate risk. As a result, the record in
this rulemaking does not adequately support listing any of
the three residuals proposed for listing. (Mobil, 00002, pg
2)

Response: EPA has refined its risk assessment analyses for
the petroleum refining waste listing based on the latest
approach and data. The two high-end parameter analysis has
been confirmed using a full Monte Carlo approach, and the
analysis continues to indicate that the waste streams
proposed for listing show risk above the discretionary
range. See other sections of this document for discussion
of specific comments raised, and see also the preamble
discussion in the final rule.

Comment 5: As discussed at length in these comments, while
several positive changes in the modeling were made (i.e.,
EPA included non-ingestion risks associated with the use of
contaminated groundwater, and attempted to evaluate a
scenario involving the co-disposal of refinery wastes), the
bulk of the modeling shortcomings remain. In most cases,
EPA either ignored the previous criticisms or attempted to
justify the errors with supplementary information. As a
result, the NODA risk assessments are also fundamentally
flawed. Moreover, in many cases, the NODA materials
actually demonstrate the weaknesses in EPA's methodologies
and rationales.

For example, the NODA materials prove the ineffectiveness of
the TCLP on oily and tarry wastes, document the potential
for free-phased flow of contaminants in refinery landfills,
demonstrate EPA's landfill active life assumptions are
extremely and arbitrarily short (thus understating
associated waste volumes substantially), and reveal co-
disposal occurs to a much greater extent than EPA has
considered.

In addition, EPA did not conduct risk evaluations for waste
management practices such as storage in piles, road
spreading, and surface impoundment management that are
plausible mismanagement practices associated with many
wastes in this rulemaking and refinery practices generally. 
Consequently, EPA's proposed no-list decisions continue to
be based upon incomplete risk analyses.

Accordingly, the fact remains that a proper risk evaluation
of the refinery wastes in the instant rulemaking would
result in the listing of at least eight wastes as hazardous. 
EPA's groundwater modeling methodology remains inappropriate
for the instant rulemaking because it fails to address the
potential for the free-phased flow of contaminants within
the landfill and upon leaving the landfill, and does not
take into account existing contamination when evaluating
potential risks. Moreover, even using EPA's inappropriate
methodology, revising several incorrect modeling parameters
would substantially change EPA's modeling results and
warrant the additional hazardous waste listings. These
conclusions are now supported by additional groundwater risk
analyses, and data from groundwater experts on the potential
for free-phased flow of contaminants at refinery sites, as
introduced in the next section of these comments and
discussed in greater detail throughout this document.

Finally, these comments address the propriety of several
exemptions previously proposed by the Agency. In 1995, EPA
proposed an exemption for oil-bearing residuals inserted
into the coking process, but as discussed below, neither the
NODA materials nor the 1995 proposal adequately address the
well established legitimacy recycling criteria necessary to
warrant such a broad, poorly defined exclusion, particularly
when the residuals are used for quenching purposes. In
addition, EPA proposed an exemption for the placement of
certain listed sludges into refinery wastewater treatment
systems (the so-called Headworks Exemption). While the NODA
preamble includes an EPA acknowledgment the proposal as
drafted was improperly broad, the exact intent of the Agency
remains unclear. Specific approaches to appropriately limit
the exemption are provided below. (EDF, 0006)

Response: EDF's individual comments (e.g. on Active Life,
codisposal, and waste management, and use of TCLP issues)
are addressed elsewhere in this document. The Agency's
analysis of the petroleum residuals indicates that no free
oil was present in any of the samples (Comment 7a in Section
I.C.1); therefore, EPA's modeling methodology assuming
aqueous phase transport of contaminants was appropriate. See
Comment 8f in Section I.C.1 concerning findings in the
Waterloo report. Please also see comment 1 in section I.A.
6g. for response to the issue of existing contamination. 

Comment 6: The additional analyses included in the NODA are
not adequately responsive to the criticisms of the risk
assessment modeling EPA performed in 1995 and relied upon
for its proposed negative listing determinations. They
contain many of the same flaws, and additional shortcomings,
that result in substantial understatements of the risks
posed by the wastes at issue.
Correction of only some of these flaws produces risk results
that justifying listing many of the refinery wastes as
hazardous, as demonstrated by other groundwater modeling
referenced in these comments.

In addition, even with the NODA materials regarding the
proposed recycling exemption, EPA has yet to address many of
the requisite findings needed to reach a valid legitimacy
determination, including whether the alleged recycling
activities are economically motivated largely by avoided
disposal costs, whether the specifications for the residual
are selected to meet a recycling purpose, whether the
hazardous constituents in the waste contributes properties
of value to or are actually necessary for the product, and
whether adequate records are kept. The failure to consider
these legitimacy criteria is particularly problematic in the
case of the use of residuals in the coker for quenching
purposes. (EDF, 00006, pg. 77)

Response: See Section I.A response to Comment 2 for detailed
discussion of comments on additional groundwater pathway
analyses performed for NODA. See Section II.B for
discussion of the proposed recycling exemption.

Comment 7: In RCRA 3001(e), Congress directed EPA to "make
a determination of whether or not to list" certain wastes,
including petroleum refining wastes. EPA lists a waste as
hazardous if "the waste is capable of posing a substantial
present or potential hazard to human health or the
environment when improperly . . . managed," after
considering certain factors such as the "potential of
[toxic] constituents . . . to migrate from the waste into
the environment under the types of improper management" that
are considered. 40 CFR 261.11.

In the Proposed Petroleum Refinery Waste Listing Rule, EPA
failed to consider plausible mismanagement scenarios and to
reasonably analyze the potential for toxic constituents in
petroleum wastes to cause groundwater contamination from
land disposal. As discussed below, the extensive re-
evaluation that EPA conducted in response to public comments
described in the NODA continues to violate the legal
standard for making the listing determination required by
RCRA 3004(e). (ETC, 0005)

Response: The agency believes it has considered plausible
management scenarios. Individual issues raised by ETC are
addressed elsewhere in this document and the preamble for
the final rule.

Comment 8: Phillips has participated in the development of
comments by API. Phillips endorses and incorporates by
reference those comments. There are several specific
aspects of the NODA that Phillips wishes to particularly
emphasize by submitting comments in addition to the
comprehensive comments prepared by API. The Phillip's
comment relate to:

 EPA's proposal not to list eleven residuals is support
 by the NODA analyses

 Groundwater pathway risk analysis oversights

 Need for listing tailored for only demonstrated high-
 risk management practices
 (conditional/listings/contingent management)

 Appropriateness of the proposed headworks exemption

Phillips urges EPA to reevaluate its risk calculations
taking into account the technical comments made by API. 
Proper application of TC cap values, distances/dispersion
from onsite landfills to receptor wells, the influence of
biodegradation, and consideration of the time lag (>1500
years) for arsenic to encounter a receptor well (long after
any risk from benzene would have occurred) are just a few of
the changes that will likely result in anticipated risks
that do not justify a hazardous waste listing for the three
residuals proposed for listing in addition to those eleven
residuals not proposed for listing. If after the risk
assessment is complete, there still remains specific
pathways that do pose a risk to human health or the
environment, the listing should be tailored to regulate only
those pathways or management methods of concern. Other
methods of management (i.e., those without demonstrable
risk) including under the toxicity characteristic. Phillips
applauds EPA's approach in the recently-issued military
munitions waste rule (62 FR 6622, 6655-56 (Feb. 12, 1997))
for distinguishing and allowing a contingent management
regulatory approach. (Phillips, 00014)

Response: The Agency appreciates the commenter's views
regarding the contingent management approach. The
individual issues raised by API such as TC Capped analysis,
well distances, dispersion of contaminants, biodegradation
and retardation of arsenic are addressed later in this
document.

I. Additional Information

Comment 1: Revised Risk Assessments

EPA's proposal to list clarified slurry oil sediment and
spent hydrotreating/hydrorefining catalysts is based on a
flawed risk assessment. The following section identifies
numerous flaws in the groundwater and Non-groundwater
pathways of the risk assessment which should be corrected
prior to a listing determination. API is confident that
once these flaws are corrected and the risk assessment
models are rerun, EPA will agree that the three refinery
residuals currently proposed for listing should not be
listed as hazardous wastes. (API, 00009, pg 10)

Response: EPA does not agree with the commenters claim, and
responses to specific criticisms of EPA's modeling are
presented in the appropriate sections of this response
document. EPA notes, however, that the decision to list CSO
sediment was not based primarily on groundwater pathway risk
(see proposed rule 60 FR 57764, November 20 ,1995, and the
NODA 62 FR 16747, April 8, 1997). Furthermore, EPA's revised
analysis for individual risk using both a two high-end
parameter analysis and a full Monte Carlo approach are
presented in detail in background documents.,

I.A. Supplemental Background Document: Groundwater Pathway
 Risk Analysis: Petroleum Refining Process Waste Listing
 Determination

Comment 1: Relying on EPA data gathered by the Superfund
program and other sources, University of Waterloo scientists
document the contamination of groundwater with nonaqueous-
phase liquids (NAPLs) resulting from waste management
practices, including practices associated with refinery
wastes and refinery sites. As explained further below,
this report is relevant to the instant rulemaking (and is
thus provided for the record) because EPA's modeling assumes
neither NAPL formation nor NAPL migration of contaminants
once the contaminants reach the groundwater will occur, when
in fact, NAPL contamination is an important part of an
actual and potential plausible mismanagement scenario for
the refinery industry.

Throughout these comments, groundwater modeling performed by
King Groundwater Science, Inc. (KGS) is referenced. This
groundwater modeling was performed for the Environmental
Technology Council, and will be submitted to the docket by
that organization. KGS performed a series of modeling runs
reflecting modified input parameters that would correct some
of the deficiencies in EPA's methodology. The KGS modeling
results indicate that the refinery wastes previously
identified by EDF as appropriate for listing do pose
substantial human health risks via the groundwater exposure
pathway. (EDF, 00006, pg 4)

Response: EPA does not agree that consideration of NAPL
formation and migration are important in this rulemaking. 
See Section I.A.6.g dealing with comments related to
existing contamination and the Waterloo report. EPA also
does not agree with many of the assumptions made in the KGS
modeling analysis, as described in Section I.A.

Comment 2: KGS conducted a series of composite runs to
determine the potential risks using the EPACMTP model using
the adjustments discussed above. These composite runs more
closely reflect the groundwater pathway risks posed by
landfilling of refinery wastes compared to EPA's NODA
efforts. In sum, KGS made the following groundwater model
input revisions:

 Receptor well placed in the center of the plume line
 consistent with EPA listing determination policy and
 statutory mandate;
 
 TCLP values reflect the average benzene capture
 efficiency of 53% for all wastes;

 CSO landfill characteristics used as standard size for
 onsite landfills (except for the co-disposal scenario
 where the EPA modeled landfill was used);
 
 Median and high-end annual offsite waste volumes
 derived from facility-received volume data in the NODA
 were used where those volumes were higher than
 corresponding values EPA computed on a refinery-generated
basis;
 
 In the co-disposal runs, annual median waste volumes
 were derived by including the estimated contribution of
 refinery wastes not covered by the listing
 determinations;
 
 A TCLP volume-weighted value was computed in the co-
 disposal cases by assigning a benzene value of 0.25
 mg/l (half the TC characteristic threshold) to the
 codisposed wastes not covered by the listing
 determinations; and
 
 Total waste volume was computed based upon a landfill
 active life of 40 years.

KGS also conducted limited sensitivity analyses to determine
whether EPA's high-end parameters were the most sensitive
parameters given these input adjustments and the absence of
EPA sensitivity analyses for unleaded gasoline storage tank
sludge and the co-disposal scenarios. Since EPA did not
conduct any analyses in the NODA testing the relative
importance of a 30 year exposure period, this high-end value
was included in the sensitivity analysis.

The risk results for the KGS composite runs demonstrate than
many of the refinery wastes covered by this rulemaking
warrant a listing determination. The following table
compares the EPA and KGS composite modeling results for
benzene:

 Refinery Waste EPA GW Risk KGS GW Risk
 Crude Oil Tank Sludge 2.7 x 10-5 1.6 x 10-4
 HF Alkylation Sludge 4.3 x 10-6 2.3 x 10-5
 Unleaded Gas Storage Tank Sludge 1.7 x 10-6 8.8 x 10-5
 Co-disposal Onsite Landfill 9.3 x 10-6 3.5 x 10-5
 Co-disposal Offsite Landfill 1.2 x 10-5 3.9 x 10-5
 
KGS Report at 17, Table 9.

In addition, a composite run for PAHs for Off-Spec Product
and Fines disposed in onsite and offsite landfills resulted
in risks >1x10-5. KGS Report at 18, Table 10.

KGS also conducted several Monte Carlo analyses of crude oil
tank sludge using the modified input parameters. One
analysis, based upon 2,000 groundwater chemical transport
simulations, yielded a 90% risk of 5.4x10-5, a 95% risk of
1.2x10-4, and a 99% risk of 3.6x10-4, consistent with the
deterministic results for this waste. The second analysis,
based upon 10,000 realizations, yielded a 90% risk of
4.8x10-5, a 95% risk of 1x10-4, and a 99% risk of 3.7x10-4. 
Accordingly, the Monte Carlo analyses essentially confirm
the high risks associated with the deterministic modeling. 

In the case of off-spec products and fines, and CSO sludge,
hazardous waste listings are warranted based upon the PAHs
found in these wastes. For the off-spec product and fines
onsite scenario, KGS conducted high-end deterministic
modeling for benz(a)anthracene using modified input values
reflecting a standard onsite landfill (which in this case
represented a reduction in size from EPA's modeled landfill
area), increased volume (calculated for a 40 year active
landfill life), and placing the well in the plume
centerline. Setting high-end values for volume and distance
to receptor well (as EPA did in its modeling), KGS found the
resulting risk more than doubled from EPA's 2.1x10-5 to the
revised 5x10-5.

Moreover, as discussed above in Section II.A of the
comments, KGS also computed the leaching values that would
produce a 10-4 risk level using modified input parameters. 
The resulting leaching values were extremely small fractions
of the waste concentrations, indicating such leaching values
were more than plausible for these oily wastes.

Conclusion

KGS concluded: "This study indicates that for alternative
disposal scenarios for five waste streams constructed suing
realistic assumptions and decisions, higher modeled receptor
well concentrations and associated risks were obtained
compared to those reported by EPA in their groundwater
pathways risk analysis." KGS Report at 21.

The groundwater pathway risks associated with land disposal
scenarios are greater than 1 x 10-5 and clearly require the
listing of crude oil tank sludge, HF alkylation sludge,
unleaded gasoline storage tank sludge, and off-spec product
and fines as hazardous wastes under RCRA 3001(b) and (e). 
(ETC, 00005, pg 3 and 16, and EDF)

Response: The Agency completed some additional analyses to
fully respond to comments based on the results of King
Groundwater's analyses. While EPA revised some input
parameters based on these comments, EPA did not agree with
many of the assumptions in the KGS analysis. Responses to
the issues of individual parameter revisions can be found
elsewhere in this document as listed below:

a) Receptor well placed in the center of the plume line
consistent with EPA listing determination policy and
statutory mandate

See Response to Comment 1 in Section I.A.6.e.

b) TCLP values reflect the average benzene capture
efficiency of 53% for all wastes.

See Response to Comment 6.a in Section I.C.1. 

c) CSO landfill characteristics [were] used as standard
 size for onsite landfills (except for the co-disposal
 scenario where the EPA modeled landfill was used).

See Response to Comments 1 and 2 in Section I.A.6.c.

d) Median and high-end annual offsite waste volumes
 derived from facility-received volume data in the NODA
 were used where those volumes were higher than
 corresponding values EPA computed on a refinery-generated
basis.

See Response to Comment 1 in Section I.A.3.

e) In co-disposal runs, annual median waste volumes were
 derived by including the estimated contribution of
 refinery wastes not covered by the listing
 determinations.

See Response to Comment 1 in Section I.A.3.

f) A TCLP volume-weighted value was computed in the 
co-disposal cases by assigning benzene a value of 0.25 (
 its TC rule value).

See response to Comment 5 in Section I.A.3.

g) Total waste was computed based on a landfill active
life of 40 years.

See response to Comment 1 in Section I.A.6.b for a
discussion on the active live adjustments for off-site
landfills. 

Responses to other issues raised can also be found elsewhere
in this document as noted below.. 

(1) In response to this comment a high-end sensitivity
analysis was performed for Unleaded Gasoline Tank Sediment. 
The analysis is discussed in the revised risk analysis
presented in USEPA, Additional Groundwater Pathway Risk
Analysis, Supplemental Background Document, 1998 in the
docket (results are summarized in Tables A.1 and A.2).

(2) While EPA did not perform a full sensitivity analysis
for the high-end assessment for the projected co-disposal
scenario, the Agency does not believe this is important. 
EPA performed a Monte Carlo analysis for the codisposal
scenario, which indicates that co-disposal does not appear
to cause significant risk. See Section I.A.3 for further
discussion of codisposal. 

(3) Exposure Duration: In the sensitivity to exposure
duration presented in KGS's groundwater modeling report, 30-
year exposure risks appear to be erroneously calculated by
simply multiplying the 9-year exposure groundwater risk by a
factor of 3.33, corresponding to the ratio of 30/9. The 9-
year exposure risks presented in the NODA and in the
proposal were calculated from the modeled maximum 9-year
average receptor well concentrations and the 9-year exposure
duration health-based numbers (HBNs). The more accurate
approach to model 30-year exposure would be to calculate
maximum 30-year average groundwater concentrations from the
modeling results, and then calculate the risk based on 30-
year health-based numbers. Maximum 30-year average well
concentrations may be smaller than 9-year average well
concentrations depending on the peak concentration period. 
By simply scaling from risks based on 9-year exposure, the
extrapolated risk for a 30-year exposure is likely to be
overestimated. EPA conducted its own sensitivity analysis
for select representative waste streams including exposure
duration as a varied parameter (see Appendix A B to
Additional Groundwater Pathway Risk Analysis: Supplemental
Background Document, U.S. EPA, 1998). Exposure duration was
not a sensitive parameter in any of the sensitivity
analyses, and the resulting two high-end parameter
combination was not changed with inclusion of exposure
duration as a sensitive parameter. Therefore, EPA does not
believe this factor greatly affects the risk calculations.

The impacts of assumptions made in the KGS modeling on the
listing decisions are discussed elsewhere in this document
and in the individual waste sections (Section I.A.5). Other
issues related to codisposal analysis are given in Section
I.A.3.

Comment 3: Impact of Selected Groundwater Modeling
Revisions

The KGS modeling results still substantially understate the
risks posed by landfilling these refinery wastes. First,
the modeling revisions still do not reflect the true
leachability of the wastes since the modeled TCLP value
still assumes no primary leachate generation and no free-
phased contaminant migration, and thus understates actual
benzene availability. 

Second, the high-end waste volumes do not reflect a high-end
landfill active life duration, since all volumes were
derived using an average landfill life assumption. Third,
the offsite median and high-end landfill size is very small
when compared to comparable values in EPA's municipal
landfill survey, and landfill characteristics employed in
the carbamates listing determination. 

Fourth, the risk results do not take into account the
contribution of pre-existing contamination at refinery
sites, and therefore does not reflect actual contaminant
exposures under plausible mismanagement conditions. Fifth,
only a limited number of sensitivity analyses were
conducted, particularly for the co-disposal scenario. High-
end values for codisposed volume were not tested, a
potentially significant omission considering the average
annual onsite co-disposal increment attributable to other
wastes not covered by the listing determination was seven
times the median value, based upon EPA's NODA data as
discussed above. Sixth and finally, the above risk
estimates are for benzene contamination only, and do not
reflect the risks posed by other contaminants in the wastes. 
(EDF, 00006, pg 46)

Response: The Agency does not consider the modified input
parameters used by KGS in the modeling to be appropriate
(see Comment 2 above); therefore, the increased risks shown
in KGS's modeling are not appropriate. As for the modeling
analyses of benz(a)anthracene, they were performed by KGS
with inappropriately modified input parameters as discussed
above. Individual responses to items 1 - 6 above are listed
below:

1. The true leachability of the waste because the TCLP
 test does not assume primary leachate generation and
 free-phased contaminant migration;

See responses to comments 7.a, 8.c, 7.f and 7.g in Section
I.C.1.

2. High-end waste volumes that incorporate high-end
 landfill active life duration, since all volumes were
 derived using only an average landfill life assumption;

The selection of a high-end active landfill life would make
the analyses a three high-end parameter analyses and as such
would have been overly conservative. As noted in the
response to comments on estimating active landfill life (see
Section I.A.6.B), the data for active life are limited, and
EPA does not believe that adequate data for off-site
landfills exist to allow the assumption of an appropriate
high-end for this parameter. Further, EPA would typically
use the median value if evaluating the sensitivity of the
results to active life, but the median value also was not
available. In the absence of adequate data, therefore, EPA
decided to use the average estimate for landfill life.

3. Appropriate offsite median and high-end landfill areas;

See response to the comment given in Section I.A.6.c.

4. The contribution of pre-existing contamination at
 refinery sites to receptor well contamination;

See response to Comment 2 in Section I.B.

5. Risks posed by contaminants other than benzene in the
 waste; and

The Agency does not know what other contaminants to which
the commenter is referring. EPA evaluated risks from all
chemicals of concern in the waste, either in bounding
analysis or high-end/Monte Carlo analyses. In addition, EPA
notes that risks for individual contaminants practically are
not necessarily additive, since peak concentration arrival
times vary as a function of chemical transport properties. 
Therefore, consideration of only benzene is not overly
conservative.

6. Risks posed by contaminants other than benzene in the
 waste; and

EPA has performed full sensitivity analyses for all wastes
of potential concern in the revised modeling results. 
Concerning codisposal, EPA believes that the Monte Carlo
analysis, which considered all volumes (not just the median
values) is an appropriate way to evaluate this scenario; see
Section I.A.3 for further discussion.

I.A.1. Revised High End Analysis

Comment 1: EPA's Determination of High-end Parameters Fails
To Consider Correlated Variables

EPA's determination of high-end parameters in the
groundwater model fails to consider the potential
correlation between waste volume and surface area. As a
result, EPA determined risks using a 90th percentile value
for waste volume and a 50th percentile value for surface
area. EPA's groundwater model is thus forced to generate
unrealistic values of waste depth. For example, in the case
of off-site hydrorefining catalyst analysis for arsenic, the
inappropriate use of 90th and 50th percentile values for
waste volume and surface area results in a depth of waste of
4.1 m. To remedy this error, API recommends that EPA
reevaluate the high-end parameters selected for the
groundwater model considering the correlation between waste
volume and surface area, thereby, keeping both parameters at
their 90th or 50th percentile values. (API, 00009, pg 16)

Response: The Agency believes that there may not necessarily
be a strong correlation between surface area and waste
volume, particularly when evaluating single waste stream
disposal. Furthermore, because the waste quantity and waste
concentration were constant values in this analysis and were
not derived parameters, the total mass of contaminant, a key
element of valid risk analysis, was conserved in the
analysis and did not vary as a function of landfill area
and depth. 

I.A.2. Monte Carlo Analysis

Comment 1: The Monte Carlo Risk Analysis Should Be the
Basis for the Listing Decision.

The Monte Carlo based risk assessment is well recognized
both at EPA and in the statistical modeling community as a
superior technical approach to conducting a risk assessment. 
Use of the Monte Carlo risk assessment would be consistent
with the Agency policy to use the best and most accurate
modeling techniques in developing a regulation. The
deterministic risk assessment, on the other hand, does not
allow EPA to determine what percentile of the risk
distribution is represented by the "high-end" analysis. 
This information is necessary to make a defensible listing
determination. (NPRA, 00004, pg 2)

Response: The Agency's "Policy for Use of Probabilistic
Analysis in Risk Assessment" states that "...such
probabilistic analysis techniques as Monte Carlo analysis,
given adequate supporting data and credible assumptions, can
be viable statistical tools for analyzing variability and
uncertainty in risk assessments." The policy also states
that "It is not the intent of this policy to recommend that
probabilistic analysis be conducted for all risk assessments
supporting risk management decisions." In addition, as one
of the conditions for using Monte Carlo analysis, the policy
states that "Calculations of exposures and risks using
deterministic (e.g. point estimate) methods are to be
reported if possible." Thus the Agency policy is a far cry
from the commenter's contention that information from Monte
Carlo analysis is necessary to make a defensible listing
determination. The Agency believes that, for this listing
determination, Monte Carlo analysis can be a helpful tool
for supplementing the deterministic analysis by providing
additional information on variability and uncertainty.

The Agency agrees with the commenter that the Monte Carlo
approach allows the EPA to determine the percentile of the
risk distribution represented by the two high-end analysis. 
However, as is evidenced in the revised risk results, both
the two high-end parameter and the Monte Carlo analyses show
risk above the discretionary range for waste streams being
listed.

Comment 2: Proper Consideration of Potential Individual
Risks Supports Not Listing Spent Hydrotreating Catalysts

The results of EPA's risk assessment for landfilling of
spent hydrotreating catalyst clearly indicate that this
residual should not be listed as hazardous waste. As
reported by EPA, potential TC-capped risks associated with
both on-site and off-site disposal range from 2x10-5 to
4x10-6 from exposure to benzene (62 FR 16752). Clearly, these
high-end risk levels are within EPA's discretionary range
for not listing (see 59 FR 66073) and are likely
overestimates of the actual risk level (EPA appropriately
reports the risks from arsenic as not applicable because
spent catalysts containing arsenic at levels sufficient to
pose such risks are already covered by the TC Rule, and
regulated under RCRA as hazardous wastes; thus, these
residuals cannot be disposed in Subtitle D landfills). When
evaluating other residuals with potential risks in the same
range, EPA appropriately proposed not to list these
residuals. For example, TC-capped risks from on-site
landfilling of crude oil storage tank sediment range from
2x10-5 to 3x10-6. Based upon these risk levels, EPA did not
consider landfilling of crude oil storage tank sediment to
warrant a listing. 

More importantly, EPA cannot ignore the results of the Monte
Carlo analysis for hydrotreating catalyst which report on-
site and off-site risks of only 4x10-6 at the 95th
percentile. According to recently released policy on Monte
Carlo analysis, "...risk assessments using Monte Carlo
analysis ... will be evaluated and utilized in a manner that
is consistent with other risk assessments...". In
addition, EPA's guidance on Monte Carlo analysis states
that Monte Carlo analysis is "...useful when screening
calculations using conservative point estimates that fall
above the levels of concern. Other situations [where it
could be useful] could include when it is necessary to
disclose the degree of bias associated with point estimates
of exposure;...when the cost of regulatory or remedial
action is high and the exposures are marginal; or when the
consequences of simplistic exposure estimates are
unacceptable." Based upon this guidance, it is clear that
Monte Carlo analysis is the appropriate tool to use in
evaluating petroleum refinery residuals.

Although the results of EPA's point estimate analysis do not
fall above the level of concern, they do fall within EPA's
discretionary zone. Due to subjective nature of the listing
decision, it is important that EPA clearly understand the
degree of bias associated with the high-end results. The
Monte Carlo analysis is further necessary because the costs
of the listing decision are relatively great compared to the
marginal exposures reported from the population level risk
assessment. As a result, the finding of a 4x10-6 risk is an
appropriate basis for reaching a decision not to list spent
hydrotreating catalyst.
 
A no list decision for hydrotreating catalyst is further
supported by EPA's evaluation of potential population risks. 
The maximum population risk associated with this residual is
an annual cancer incidence rate of 0.00003 or only three
cases of cancer in 100,000 years. These population risks
are clearly negligible and do not support EPA's proposed
listing decision (as described further below). (API, 00009,
pg 3)

Response: As indicated above, the Agency is using the Monte
Carlo analysis as a source of additional information on the
variability and uncertainty of the deterministic analysis. 
In conducting the Monte Carlo analysis for the Notice of
Data Availability (NODA), the Agency made a key assumption
concerning well location which was inconsistent with the
assumption made for the deterministic analysis. In the
deterministic analysis, the down gradient wells of concern
were assumed to be those within the plume of contamination
from the landfill. For the Monte Carlo analysis, all
potential wells on the downgradient side (within a 180
degree arc) from the landfill were included, thus including
wells which would never be affected by contamination from
the landfill. Since the Agency is interested in risk only
at well locations which could be affected by the landfill,
the Monte Carlo analysis was corrected to include only those
well locations which were within the plume. The results of
this correction, along with the other corrections to waste
volume and landfill area estimates which were described
earlier, show that risks are higher than previously reported
for different percentiles on the Monte Carlo distribution as
well as for the deterministic analysis. The results are
presented in, Additional Groundwater Pathway Risk Analysis,
Supplemental Background Document. 
 
Furthermore, it is important to note that the Agency
policies do not indicate there is any particular point on a
Monte Carlo distribution which should be the point at which
the Agency regulates or does not regulate. The 1992
memorandum the then Deputy Administrator F. Henry Habicht
"Guidance on Risk Characterization for Risk Managers and
Risk Assessors" states that "The high end' of the risk
distribution [generally the area of concern for risk
managers] is, conceptually above the 90th percentile of the
actual (either measured or estimated) distribution. This
conceptual range is not meant to precisely define the limits
of this descriptor, but should be used by the assessor as a
target range for characterizing high end risk'." 
Therefore, a high end estimate which falls within the range
(above the 90th percentile but still realistically on the
distribution) is a reasonable basis for a decision.

A revised analysis conducted by EPA including a 30 year
active life and a municipal landfill area distribution
indicates that the TC-capped risk for exposure to benzene
from hydrotreating catalyst is 2.6E-05.16 Furthermore, no
TC-capped risk for benzene from hydrotreating in any of the
revised two high-end parameter analyses is below 2.0E-05.
See also response to comment 1 in Section I.A.2.

EPA responds to the general comments on population risk in
Section IV.B. EPA believes that the individual risks noted
above are sufficient to warrant listing, despite relatively
small population risks.

Comment 3: Proper Consideration of Individual Risk Supports
Not Listing Spent Hydrorefining Catalysts

The results of EPA's risk assessment for landfilling of
hydrorefining catalysts support not listing hydrorefining
catalysts as a hazardous waste. According to EPA, potential
TC-capped risks to an individual from benzene range from
2x10-5 to 6x10-6 (62 FR 16752). As discussed for
hydrotreating catalysts, these risk levels are clearly
within EPA's discretionary range for listing (59 FR 66073). 
The EPACMTP model predicts that these risks will occur in 13
to 50 years.

EPA also reports that potential TC-capped risks from
landfilling hydrorefining catalyst containing arsenic range
from 4x10-4 to 1x10-4. Although these high-end potential
risks suggest that EPA could consider listing hydrorefining
catalyst as a hazardous waste, it is clear that EPA did not
adequately consider the results of the groundwater model
before reporting these results. Unlike the risks reported
for benzene, the EPACMTP model predicts that the arrival of
peak arsenic concentrations at the receptor well will occur
between 3400 and 8400 years after the source is released. 
Measurable concentrations would not begin to reach the well
until after 1500 years. Obviously, these data suggest that
there is no significant off-site migration of arsenic. 
Thus, EPA's entire risk assessment for arsenic is based upon
the assumption that the landscape will not change over the
next 3400 to 8400 years. This assumption is extremely
implausible and renders the arsenic risk assessment
unrealistic, at best.

In addition, the timing of peak concentrations at the
receptor well prohibits EPA from adding together the risks
from benzene and arsenic. API's analysis indicates that the
risks from benzene and arsenic cannot occur simultaneously. 
In fact, there is a minimum of 3350 years between peak
concentrations at the receptor wells for these constituents. 
As a result, EPA should base its listing determination for
hydrorefining catalysts on the results of the more plausible
benzene risk assessment. Any other decision would require
costly protection against a risk that is extremely unlikely
to occur.

When evaluating the risks from benzene, EPA cannot ignore the
results of the Monte Carlo analysis. As stated above, the
Monte Carlo analysis indicates that EPA's high-end analysis
has conservatively predicted risks and should not be used
when making a list/no list decision. In contrast to the
findings of the high-end analysis, the Monte Carlo analysis
reports a risk of 6 x 10-6 at the 95th percentile.

Finally, a no list decision for hydrorefining catalyst is
supported by EPA's evaluation of potential population risks. 
Maximum off-site population risks from landfilling of
hydrorefining catalyst are limited to 0.2 cases of cancer in
10,000 years. As described in more detail below, on-site
population risks are significantly smaller given that the
entire population within one mile of the landfill is limited
to a single individual. These population risks are clearly
negligible and do not support EPA's proposed listing
determination. (API, 00009)

Response: The Agency disagrees with the commenter
concerning the listing of the two catalysts. The peak
arrival time for benzene in the current revised analyses is
between 30 and 40 years, while the peak arrival time for
arsenic in the current revised analyses for both industrial
and municipal landfill area distributions is between 3000
and 3500 years for the various analyses (industrial areas,
municipal areas, 30 year landfill life, 20 year landfill
life etc.). However, the modeling analysis has been
conducted to protect the environment and human health for a
period of 10,000 years. Therefore, if peak arsenic levels
occur at greater than 3000 years, those peaks must still be
considered. Also, if the landscape changes within those
10,000 years the contamination within the landfill will
still be present. There is a very low chance of a geologic
event occurring that will remove the landfill and its
contamination from the landscape. It may be buried and/or
excavated by natural processes, but that will not neutralize
the contamination. Furthermore, the individual risks for
benzene and arsenic are high enough to warrant listing
without adding the risks and the decision to list
hydrorefining catalyst waste was based on the independent
risk results for both arsenic and benzene. Furthermore the
current revised analyses show that the TC-Capped analysis
receptor well risks are 1E-06 at about 1,700 years and they
are 1E-05 at about 1,900 years, much earlier than the peak
arrival time.

In response to comments on the NODA, the Agency further
revised the input data for the groundwater pathway analysis
as noted elsewhere. As a result of the revised risk
analysis, the off-site landfill groundwater risks increased
further. The revised off-site risks for hydrotreating
catalyst are 1E-04 for benzene and 8E-05 for arsenic; the
TC-capped results for this waste showed lower risk for
benzene (3E-05), but arsenic was unchanged. Similarly, the
revised off-site risks for hydrorefining catalyst are 7E-05
for benzene and 6E-04 for arsenic, and the TC-capped
analysis for this wastes lowered the benzene risks (3E-05)
but had no impact on arsenic risk. The revised Monte Carlo
risks for hydrotreating catalyst (benzene 3E-5, arsenic 2E-5
at the 95th percentile) and hydrorefining catalyst (benzene
2E-5, arsenic 4E-4 at the 95th percentile) were somewhat
lower, but still well above the listing benchmark of 1E-5. 
As in the NODA analysis, the high-end and Monte Carlo risks
for arsenic were not lowered by the TC-capped analysis. 
While the TC-capped risks for both catalysts were somewhat
lower in the high-end (both at 3E-5) and Monte Carlo
analysis (9E-6 and 8E-6 for the hydrotreating and
hydrorefining risks respectively), EPA believes that the
overall results are strongly supportive of listing both
spent catalysts. Even in the TC-capping results, both
catalysts present risks in off-site landfills that exceed
1E-5. Specifically, for both hydrotreating and
hydrorefining catalysts, the TC-capped arsenic risks exceed
1E-5 for the Monte Carlo and high-end evaluations, and the
benzene risks exceed this benchmark in the high-end
evaluation and approaches this level in the Monte Carlo
analysis. In addition to the groundwater risks posed by
these materials, the pyrophoric and self-heating nature of
these catalysts also support EPA's conclusion that these
materials present a substantial hazard.

Comment 4: EPA Should Base Its Listing Determinations for
the Groundwater Pathways on the Monte Carlo Analysis Rather
than the Deterministic Results

EPA presents both a revised high-end analysis and a Monte
Carlo analysis for the groundwater pathways. API strongly
recommends that the Monte Carlo analysis serve as the basis
for a list/no-list decision, due to the superior quality of
the Monte Carlo-based risk estimates in comparison to the
deterministic risk estimates. In the NODA, EPA states that
the Monte Carlo analysis is used only to "confirm" the risk
findings (62 FR 16750-51). API disagrees with this approach
and urges EPA to fully consider the outcome of the Monte
Carlo results when finalizing the listing determination. 
The Monte Carlo results should be used as the primary
determinant of individual risk.

EPA guidance, has recognized the superior quality of Monte
Carlo-based risk estimates compared to high-end approaches. 
Specifically, EPA has recommended that, where actual dose
distributions are not available, but information on the
variability in concentrations, activity patterns, and other
patterns are, that modeling such as Monte Carlo simulation
is an appropriate substitute. EPA also indicated that
deterministic analyses aimed at estimating the high-end
exposure (such as EPA's "high-end" analysis in the proposed
rule) should be used "if only limited information on the
distribution of the exposure or dose factors is available,"
which is not the case in this rulemaking. In the absence of
the Monte Carlo analysis, it is impossible to determine what
percentile of the risk distribution is represented by the
"high-end" analysis. Using the risk estimate from the Monte
Carlo analysis will ensure that EPA achieves "transparency,
clarity, consistency, and reasonableness," as stated by EPA
guidance (1995), in its risk characterization for this
proposed rule. (API, 00009, pg 14)

Response: See Response to Comment 1 in Section 1.A.2.

Comment 5: Listing Determinations for the Groundwater
Pathways on the Monte Carlo Analysis Rather than the
Deterministic Results

EPA presents both a revised high-end analysis and a Monte
Carlo analysis for the groundwater pathways. Phillips
strongly recommends that the Monte Carlo analysis serve as
the basis for a list/no-list decision, due to the superior
quality of the Monte Carlo-based risk estimates in
comparison to the deterministic risk estimates. In the
Federal Register notice, EPA states that the Monte Carlo
analysis is used only to "confirm" the risk findings. 
Phillips agrees with this statement and urges EPA to fully
consider the outcome of the Monte Carlo results when
finalizing the listing determination. (Phillips, 00014)

Response: See Response to Comment 1 in Section 1.A.2.

I.A.3. Co-disposal

Comment 1: In evaluating the risks posed by plausible
mismanagement, EPA must consider the actual and potential
co-disposal of refinery wastes in both on-site and off-site
landfills. Such co-disposal can produce the free-phased
flow of contaminants in a landfill, which makes EPA's
reliance solely on the TCLP as a predictor of contaminant
migration seriously flawed. The most likely scenarios are
(1) co-disposal of different kinds of petroleum wastes
covered by the rulemaking in the same landfill; (2) co-
disposal of the same waste from multiple refineries at one
offsite landfill; and (3) co-disposal of covered wastes with
other petroleum refinery wastes in the same on-site or off-
site landfill.

Unfortunately, in the NODA the agency has addressed only the
first co-disposal scenario listed above. By ignoring the
other two co-disposal scenarios, EPA has substantially
underestimated the risks posed by the refinery wastes
covered by this rulemaking. To account for this deficiency,
KGS considered the effect of other codisposed wastes. In
composite run analyses, KGS adjusted the volume-weighted
TCLP value for codisposed wastes to reflect the higher
benzene values reasonably expected in soils contaminated
with product and crude oil, other oily sludges and organic
wastes, and other codisposed wastes not covered by the
rulemaking. (ETC, 00005, pg 13)

Response: In the groundwater pathway analysis the Agency
modeled both scenarios (1) and (2) described in the comment,
contrary to the cementers assertion that the Agency
considered only scenario (1) in this analysis. In both the
single-wastestream and the co-disposal scenarios for offsite
landfills the waste volumes were calculated on a facility
received basis, i.e. a management unit loading method was
used. They were not based on the refinery of origin as
the commenter claims. Scenario (3) was not considered
because the intent of the 1994 consent decree was to analyze
the incremental risk of the 29 residuals considered in this
rulemaking, and the commenter's approach was highly
speculative. EPA responds to the specific issues in more
detail below. For this reason, residuals not included in
the rulemaking were not included in the codisposal analysis. 
EPA responds to the specific TCLP concentration modeling
assumptions used by the commenter in Comment 5, below.

Comment 2: In its comments on the 1995 proposal, EDF argued
the Agency's risk assessments were flawed because they did
not take into account both actual and potential co-disposal
of refinery wastes. As discussed above, such co-disposal
can produce the free-phased flow of contaminants in a
landfill, rendering the TCLP ineffective as a predictor of
contaminant migration from the landfill. In addition,
properly taking into consideration co-disposal would
increase the volumes of wastes that are landfilled, and
affect other landfill modeling assumptions.

Co-disposal can be subdivided into three categories. First,
the same type of waste (i.e., unleaded gasoline tank storage
sludge) can be codisposed from multiple refineries at one
offsite facility, a scenario that is both documented by EPA
and probable given the geographic concentration of
refineries in the United States. Second, a combination of
wastes covered by this rulemaking (including the study
wastes) can be codisposed in the same onsite or offsite
facility. Third, the wastes covered by this rulemaking can
be codisposed with other refinery wastes in the same onsite
or offsite landfill.

In response to EDF's comments, EPA included in the NODA
materials an onsite and offsite co-disposal scenario that
attempts to reflect the second category of co-disposal only. 
By ignoring the other two co-disposal categories, and
inadequately addressing the second category, the NODA
groundwater risk assessment substantially understates the
potential risks posed by the co-disposal of refinery wastes. 
(EDF, 00006)

Response: EPA used the first scenario described by the
commenter in the proposed rule. The commenter correctly
points out that EPA assessed the second scenario in the
NODA, and did not model the third scenario. The commenter
provides more detailed comments on each of these scenarios
in comments 3, 4, and 5 in this section; EPA provides its
response to these criticisms later in this section as well.

Comment 3: The Co-disposal of Individual Wastes at Offsite
Landfills

As discussed above, the waste volume parameter for the
groundwater modeling is derived by multiplying the annual
waste quantity (based upon 1992 data) and the length of the
unit active life. For the annual waste quantity, EPA
computed median (50%) and high-end (90%) values based upon
1992 generation data provided from each refinery. 
Accordingly, EPA's computation reflects annual waste
quantities on an individual refinery basis, not on a
facility received basis. In the case of onsite landfills,
this distinction does not matter, since onsite landfills
would receive only wastes generated by that refinery. 
However, in the case of offsite facilities, the distinction
matters because offsite facilities can and do receive the
same refinery wastes from multiple sources. Therefore,
median and high-end waste volumes received at offsite
facilities may differ significantly from analogous values
computed on an individual refinery basis.

In projecting plausible mismanagement scenarios, EPA must
compute median and high-end annual waste volumes on both an
individual refinery and receiving facility basis, and choose
the higher values for its modeling. Volumes derived on a
refinery basis reflect one plausible mismanagement scenario
since refineries may adjust their disposal practices from
year to year. Volumes derived on a facility received basis
reflect a second plausible mismanagement scenario since they
are based on actual co-disposal occurring in the surveyed
year. Since both scenarios are plausible, EPA's modeling
should take into account the scenario posing the greatest
potential risk for the individual waste stream.

Table B.2 of the NODA Groundwater Risk Assessment provides
the waste volumes for each waste type on an offsite facility
received basis. From the data provided in this table,
median and high-end volumes can be derived for each waste. 
For at least three wastes, the as received volumes are or
may be higher than EPA's refinery-based values. Those
wastes are crude oil tank sludge, unleaded gas tank storage
sludge, and off-spec thermal products and fines. A
comparison of the refinery-based and offsite facility-based
median and high-end volume values for these wastes (based
upon a 40 year active life for the reasons explained above)
is as follows:

 EPA's Refinery- Facility-Based
 Based Volume Volume
 (40 yrs, cubic m) 
Crude Oil Tank Sludge 

 Median 782 1,678
 High-End 16,632 21,424

Unleaded Gas Tank Sludge

 Median 193.8 154
 High-End Not Provided 1,719

Off-Spec Products & Fines

 Median 2,880 10,978
 High-End 20,920 112,562

Thus, for these wastes and perhaps others, EPA's volume
parameters substantially understate the actual quantities of
wastes codisposed, based upon the reported co-disposal
offsite by multiple refineries contained in EPA's database. 
The offsite annual waste quantity values should be revised
to reflect the higher of the median/high-end values computed
on a refinery and receiving facility basis. 

KGS revised the annual offsite waste quantities to reflect
the Table B.2 values where higher than EPA's offsite annual
waste quantities, and incorporated the revised quantities
into its composite modeling runs. Accordingly, the KGS
composite modeling runs more closely reflect the groundwater
risks posed by landfilling refinery wastes. (EDF, 00006)

Response: The commenter has misinterpreted EPA's waste
quantity calculation methods. EPA did not calculate any
landfill disposal quantities on an individual refinery
basis, as the commenter claims, but rather calculated all
quantities on a facility received basis. The commenter
correctly points out that Table B.2 of the NODA and the 1995
Listing Background Document provide different results. 
However, EPA clarifies that Table B.2 of the NODA represents
only offsite facilities, while the 1995 Listing Background
Document represents both onsite and offsite landfills. EPA
believes that each data set is uniquely appropriate for a
given evaluation, and therefore disagrees with the commenter
that EPA should use two different calculation methods and
select whatever value is higher for its deterministic risk
assessment.

In the deterministic risk assessment used for the proposed
rule, EPA elected to assess onsite and offsite landfills
using the same waste quantities. The basis for this was
EPA's judgement that a refinery could likely dispose of its
waste at either an onsite location or an offsite location. 
EPA combined the quantities received by both onsite and
offsite refineries into the same data array so that a single
set of values would be the basis for both assessments.

Conversely, the data presented in Table B.2 represents data
used for the Monte Carlo assessment. EPA conducted separate
Monte Carlo assessments for the onsite and offsite
scenarios. For the offsite scenario, EPA selected specific
landfills each with a corresponding waste volume, climatic
region, etc. Onsite landfill quantities could not be used
for the offsite Monte Carlo analysis, as they could for the
deterministic analysis.
 
In response to the specific data values presented by the
commenter, EPA wishes to correct several discrepancies. The
first column, labeled "EPA's Refinery Based Volume," is
mislabeled (as discussed above) because it actually
represents onsite and offsite facility-based volumes. 
However, these quantities correctly correspond to those
given in the 1995 Listing Background Document, taking
density into account. EPA wished to note several
discrepancies in the second column, labeled "Facility-Based
Volume." For crude oil tank sludge, the quantities should
match exactly because no onsite disposal occurred in 1992. 
However, slightly different densities were used in each case
(which do not affect the modeling results). Two additional
reasons account for the discrepancy: (1) the initial
calculation (presented in the 1995 Listing Background
Document) was based on a population of 12 offsite landfills
while the 1997 Supplemental Background Document for
Groundwater Pathway Risk Analysis, Table B.2 presents 11
offsite landfills. A landfill reporting zero quantity of
waste received accounts for the difference. (2) The 50th
percentile value in the 1995 LBD is an average of (the
middle) two values. This was erroneously calculated to be
29.75 MT. The correct value is 34.75 MT (however, all risk
calculations were based on the 29.75 MT). The difference
between these two 50th percentile values is less than 20
percent and is not expected to affect results.

For Unleaded Tank Sediment, the differences between the two
sets of values are very small after eliminating the effect
of using different values of density. Therefore, there is
essentially no difference in the 50th and 90th percentile
receptor well concentrations determined by each of the two
methods.

For Off-spec Product and Fines, the high end value in the
second column is based on an incorrect value given in Table
B.2 of the NODA. This incorrect value was not used in the
deterministic analysis used for the 1995 proposed rule but
was inadvertently included in Table B.2. Substitution of
this specific facility's incorrect value with the more
appropriate, smaller value results in the same 90th
percentile 40 year volume as presented in the first column.

As for the issue raised in footnote 25 (Unleaded Gasoline
high-end waste volumes), (1) the high-end Unleaded Gasoline
Tank Sediment waste quantity was provided in the 1995
Listing Background as was the median value used in the
modeling. The value is 2,077 cubic meters. Not 2,237
cubic meters. (2) An explanation for the difference in
waste volumes used in the NODA as compared with the waste
volumes used in the 1995 proposal was provided in the
Supplemental Background Document for Groundwater Pathway
Analyses The waste fraction approach used in the
proposal analysis resulted in derived waste volumes that
were either too large or too small. Revised (reported)
waste volumes were used in the NODA Analyses. This revision
is the reason for the difference in the Unleaded Gasoline
Tank Sediment volume. Furthermore, since high-end volumes
were not used in the proposal analyses, they were not
affected by the waste fraction issue and there were no
revised waste volumes to report.

Comment 4: The Co-disposal of Wastes Covered by Listing
Determination and Related Study

In the NODA materials, EPA assessed the groundwater risks
posed by the co-disposal of multiple wastes covered by the
instant rulemaking and a related study of refinery wastes. 
The onsite and offsite scenarios assessed deterministically
assumed the wastes were codisposed at their median volumes,
based upon a 20 year active life. Leachate values for the
codisposed wastes were derived by computing a volume-
weighted average value based upon the individual waste TCLP
sampling results. High-end values were set for waste unit
area and distance to well, without the benefit of a
sensitivity analysis to determine whether these two
parameters would produce the greatest risks at the receptor
well. 

In addition to the deficiencies discussed elsewhere in this
section unique to the co-disposal scenario, EPA's co-
disposal modeling suffered from the same shortcomings as the
modeling performed on individual wastes. Specifically, the
volume quantities are based on an incorrect 20 year active
life, the TCLP values do not reflect the leachability of
oily wastes, and the location of the receptor well was
inappropriately located outside of the plume centerline (see
next section of the comments).

Moreover, EPA's methodology assumes the volumes of listing
determination and study wastes that are codisposed will
remain forever constant, a projection for which EPA has not
presented any factual basis. In contrast, API reports that
9,922 tons of "other oily sludges and organic wastes" were
landfilled in 1992, the year on which EPA's volume data are
based. In 1993, API reports 180,221 tons of the same
wastes were landfilled, a sum over 17 times greater than the
corresponding 1992 volume. Clearly, waste volumes can
increase dramatically from the 1992 figures.

EPA's failure to conduct a sensitivity analysis for the co-
disposal scenario further exacerbates the lack of emphasis
on the potential for increased quantities of codisposed
wastes. By modeling only median waste volumes, the annual
onsite codisposed volume was only 2,170 cubic meters, and
the corresponding offsite volume was only 2,727 cubic
meters. For comparison purposes, the annual high-end
volume for CSO sludge onsite and offsite is 2,245 cubic
meters, about 17 times the CSO median value and greater than
EPA's codisposed onsite volume alone. Therefore, EPA's
modeling inputs fail to account for the co-disposal of high-
end quantities of CSO sludge and other wastes. Similarly,
the annual high-end volume quantity for HF alkylation sludge
is 1,912.3 cubic meters for both onsite and offsite,
therefore EPA's modeled co-disposal scenario assumes very
little waste is also landfilled with that high-end volume. 


Significantly, the co-disposal of high-end volumes for
various wastes is not merely a hypothetical scenario. In
its comments on the 1995 proposal, EDF documented the co-
disposal of high-end values of various wastes based upon the
1992 data alone. The potential for such co-disposal to
occur is thus both actual and potential, given the
geographic concentration of refineries in some parts of the
country.

Moreover, a review of the sensitivity analyses performed by
EPA on the individual wastes indicates waste volume is an
extremely important parameter in EPA's modeling. More often
than not, waste volume proved to be one of the two high-end
parameters that produced the highest risks at the receptor
well.

Response: EPA addresses the commenter's concerns regarding
landfill active life, appropriateness of the TCLP to oily
wastes, and plume centerline elsewhere in these comments. 
Specifically, greater discussion of active life is presented
in Section I.A.6.b of this response to comments, application
of the TCLP to oily wastes is discussed in Section I.C.1,
and plume centerline is discussed in Section I.A.6.e.

As addressed elsewhere (for example, response to comment 3
of Section III.I of the NPRM), EPA believes its use of 1992
data for the purpose of selecting waste volumes is
appropriate, because EPA has no reason to believe otherwise. 
In reference to the specific API data cited by the
commenter, API's report acknowledges the increase in volume,
explaining that it is due to a
single refinery accounting for 62 percent of the total 1993
quantity (page 22 of API's "Generation and Management of
Residual Materials, 1992-1993"). Analysis of wastes
generating in years 1987 to 1991 shows relatively constant
waste quantities (40,000 to 61,000 wet tons, from page 25 of
that source) in comparison to the 1992 value of 38,000 tons. 
Further, the API category of "other oily sludges/organic
residuals NOS" does not necessarily refer to the wastes of
concern in this rulemaking and could be a wide variety of
materials. Therefore, EPA disagrees with the commenter's
conclusion that 1992 was not a representative year. 

As for the issue of high-end waste volumes, the high-end
parameter groundwater analysis does not assume that high-
end values of parameters are hypothetical and exceed all
possible values of a particular parameter. Rather, high-end
values are based on actual statistical distributions of
parameter values from the petroleum refining database. 
Therefore, the occurrence of a landfill possessing a
property equal to the high-end value of that property is not
unexpected and does not in any way invalidate the Agency's
high-end analysis. For each landfill property, ten percent
of all landfills should exceed the 90th percentile value for
that property. However, in this case for the co-disposal
scenario, waste volume was not one of the selected high-end
parameters. Nevertheless, a comparison of the Monte Carlo
co-disposal results with the two high-end parameter co-
disposal results shows that the two high-end analysis
produced risk values well above the 95th percentile. So,
although a sensitivity analysis was not conducted for the
co-disposal scenario, the two high-end parameters selected
for the analysis based on a 1995 sensitivity analysis
produced sufficiently conservative results.

The two offsite landfills receiving large quantities of
codisposed waste noted in EDF's comments to the 1995
proposal (EDF, 00036; pp. 16 and 17; March 21, 1996) did
receive high-end quantities of waste. That waste, however,
consisted largely of FCC Fines, Off-Spec Product and Fines
(neither of which contain significant amounts of benzene)
and hydrotreating and hydrorefining waste (which are
excluded from the co-disposal analysis).

Comment 5: The Co-disposal of Wastes Not Covered by the
Listing Determination and Related Study

EPA's co-disposal modeling does not take into account the
large quantities of refinery wastes that are not covered by
the listing determinations or the related study. 
Information gleaned from the NODA materials and other
sources indicate large quantities of other refinery wastes
are codisposed with the refinery wastes at issue in this
rulemaking. EPA is obligated to consider the potential
risks posed by such co-disposal, since such co-disposal is a
plausible type of improper management. See 40 CFR
261.11(a)(3)(vii).

Attachment 1 to Chapter 6 of the NODA Background Document
provides the onsite landfill capacity used in 1992 for 23
refinery waste landfills. Importantly, the capacity
utilization value is not restricted to the wastes covered by
the instant rulemaking, therefore the collected values
provide a useful measure of the extent of co-disposal that
occurred in these landfills during 1992.

The median 1992 codisposed waste volume for these 23
landfills was 3,361 cubic meters, while the average value
was 23,879 cubic meters. As noted above, EPA's onsite
median co-disposal value was 2,170 cubic meters, or about
1,191 cubic meters less than the actual median waste volume,
and about 21,709 cubic meters less than the average waste
volume codisposed in these landfills during 1992. 

Although there is no corresponding EPA table for offsite
landfills, other sources of information can be utilized to
obtain a rough approximation of offsite co-disposal rates. 
As discussed above, API reported that the largest volume of
waste landfilled in 1992 by far was contaminated
soils/solids. Two other waste categories landfilled in high
quantities were "other inorganic residuals" and "other
residuals". Together, these three waste categories
accounted for 1,177,810 of the 1,664,887 tons of refinery
wastes landfilled during 1992, or over 70% of all landfilled
wastes.

API also reports that 92% of the contaminated soils, 92% of
the other inorganic residuals, and 72% of the other
residuals were disposed offsite during 1992. Since
according to API these wastes accounted for the vast
majority of refinery wastes landfilled during 1992, the
relative proportion of onsite/offsite management for these
wastes can be reasonably extrapolated to all refinery wastes
during 1992. Therefore, using a 75%/25% offsite/onsite
ratio for these wastes, an offsite 1992 co-disposal
contribution from wastes not included in this rulemaking can
be calculated by multiplying the onsite differential
specified above (1,191 cubic meters median value; 21,709
cubic meters average value) by three to reflect the greater
percentage of refinery wastes managed offsite. 

The result is an annual contribution of 3,573 cubic meters
(median), or 65,127 cubic meters (average) of other wastes
codisposed offsite with the wastes covered by the instant
rulemaking. These quantities are greater than the volumes
modeled by EPA in the offsite co-disposal scenario,
therefore the lack of consideration to other codisposed
wastes is a profound deficiency in the co-disposal modeling.

KGS considered the effect of "other" codisposed wastes in
two sets of modeling runs. In the first set, KGS adjusted
only the volume of the codisposed wastes to include the
median value increment estimate for wastes not included in
this rulemaking and a longer landfill active life (39.2
years onsite, 40 years offsite). Adjusting this parameter
only did not significantly affect the modeling results.

However, in the composite run analyses discussed below, KGS
also adjusted the volume-weighted TCLP value for the
codisposed wastes to reflect the higher benzene values
reasonably expected in soils contaminated with product and
crude oil, "other oily sludges and organic wastes", turbo
fuel filters, oily rags, laboratory wastes, paint waste, and
other codisposed wastes not covered by this rulemaking. 
(EDF, 00006, pg 34)

Response: EPA does not dispute the commenter's central
point that both onsite and offsite landfills contain other
refinery wastes in addition to those in the scope of today's
listing determination and EPA's related study wastes. EPA
disagrees that it should take such wastes into account
because EPA believes that it's core objective in conducting
this listing determination is to assess the incremental risk
associated with these materials. As such, it is not
appropriate to take into consideration pre-existing
contamination or co-disposal with residuals outside of the
scope of the consent decree. Such considerations are better
measures of the risk associated with landfills containing
the residuals of concern, rather than the residuals
themselves. 
In regard to the additional modeling conducted by the
commenter, EPA believes the commenter's use of an adjusted
volume-weighted TCLP concentration is arbitrary and
disagrees that the result is useful for assessing co-
disposal. In fact, the existing data available to EPA for
the refinery wastes under study show that very few of these
wastes contain such high levels of benzene. EPA has no
valid reason to project that benzene levels in other
codisposed wastes would be drastically different, as assumed
by the commenter. EPA further addresses the commenter's
modeling of co-disposal in Section I.A.3, comment 2 of this
NODA comment response.

Comment 6: The Practice of Co-disposal Is Trivial in Both
Potential Risks and Likely Occurrences

As part of the NODA, EPA evaluated the risks associated with
disposal of two or more residuals in the same land treatment
unit (LTU) or landfill. In all cases, incremental risks
associated with the co-disposal scenario were trivial and
did not affect EPA's proposed no listing determinations. 
Although API disagrees with the need to evaluate co-disposal
as a management scenario, API agrees that the analysis
clearly demonstrates that risks associated with co-disposal
are insignificant. In the case of LTUs, API also supports
EPA's use of site-specific data to identify and model those
few facilities that accepted several different residuals. 
(API, 00009, pg 11)

Response: EPA acknowledges the commenter's support
regarding the co-disposal analysis.

I.A.4. Capping Waste Analysis Results at TC Levels

Comment 1: Inappropriate TC Capped Modeling

In the NODA Groundwater Risk Assessment, EPA conducted
additional groundwater monitoring analyses of individual
wastes and the co-disposal scenario where the TCLP values
for wastes disposed in the landfill were capped at the
toxicity characteristic threshold concentrations of 0.5 mg/l
for benzene and 5.0 mg/l for arsenic. The implication of
this modeling is the existing toxicity characteristic may be
an appropriate alternative to listing the wastes covered in
this rulemaking. For the host of reasons discussed in this
portion of the comments, this TC capped modeling and the
underlying implication are both technically and legally
flawed.

First, the modeling approach presumes the TCLP is an
accurate and consistent indicator of benzene availability,
but as discussed at length above, the TCLP is ineffective on
many oily and tarry wastes in this rulemaking and fails to
account for potential free-phased flow in the landfill. 
Therefore, TCLP results are not an accurate or consistent
indicator of benzene availability, whether or not a
particular TCLP benzene concentration is above the
characteristic threshold. The more relevant arbiter of risk
is the total concentration of benzene in the waste.

Second, the approach is based upon the unsupported
assumption that all wastes exhibiting the toxicity
characteristic for either benzene or arsenic are properly
managed as hazardous wastes. However, as EPA is well aware,
federal law does not require testing of wastes to determine
whether they exhibit a hazardous waste characteristic. 
Instead, a generator may simply apply "knowledge" to render
a hazardous waste determination. See 40 CFR 262.11. In
EPA's own words, this regulation - 

 ...has hindered enforcement efforts aimed at
 regulating generators and potential generators or
 individual waste streams under RCRA. There is no
 self-reporting mechanism to identify generators
 who claim to eliminate characteristic hazardous
 waste from the RCRA system. To take an
 enforcement action, EPA or the state must sample
 and analyze the waste to determine if the waste
 exhibits any of the hazardous waste
 characteristics.

Moreover, EPA also acknowledged at the same time that very
few generators receive inspections at all, let alone on a
routine basis. Under these circumstances, where EPA
admits enforcing appropriate hazardous waste characteristic
determinations generally is extremely problematic, and TCLP
results on oily wastes are erratic at best thereby
exacerbating the inaccuracies resulting from applying
generator "knowledge", EPA is obligated to consider the
plausible mismanagement scenario of the disposal of
characteristic refinery wastes in nonhazardous waste
landfills. Specifically, it is quite plausible that
refinery generators may render inaccurate hazardous waste
determinations on oily refinery wastes, and regulatory
authorities will not identify these inaccurate
determinations for years, if at all.

Evidence of this plausibility is reflected in the docket for
the NODA and other sources. Included in the docket is a
Criminal Information filed by the U.S. Attorney for the
District of New Jersey describing the improper shipment and
management of 617,980 pounds of characteristic refinery
waste as nonhazardous. The waste involved sometimes
exhibited a hazardous waste characteristic, and in this
instance, the company improperly relied upon a TCLP sample
of a previous batch of wastes to wrongly conclude the
offending wastes was nonhazardous when, in fact, it
exhibited the toxicity characteristic for benzene. 

In addition, RCRA noncompliance resulting from inadequate
hazardous waste determinations is apparently an important
enough problem in EPA Region VI that the Region commenced
roundtable discussions with the industry, and posted
guidance on the Internet, to try to begin addressing the
problem. 

Significantly, the plausibility of inaccurate hazardous
waste determinations is an expressed consideration in
hazardous waste listing determinations. One of the criteria
for listing a hazardous waste is whether the waste exhibits
a hazardous waste characteristic. See 40 CFR 261.11(a)(1). 
This criterion would be unnecessary and duplicative if there
were no advantage or benefit to listing an otherwise
characteristic waste. However, the principal advantage of a
listing is the ease of implementation, including
enforcement. 

In the enforcement case discussed above, if the waste was
listed as hazardous, the issue of whether TCLP results were
appropriate for a particular batch of wastes would not have
arisen, because the application of hazardous waste
requirements would have been clear and uncontrovertible from
the outset. The fact that the criminal investigation and
prosecution took years to bring is evidence of the fact that
thousands of documents had to be reviewed to overcome the
inconsistencies of the TCLP and the defendant's "knowledge"
of the waste necessary to prove the violation of law. 
Therefore, in reaching the listing determination, EPA must
consider the plausible enforcement shortcomings of
maintaining a characteristic-based approach for the refinery
wastes.

It is also reasonable to interpret the term "improper
management" found in the statutory definition of hazardous
waste, and EPA's regulatory listing criteria, as inclusive
of management not in accordance with applicable law,
particularly where such law contains acknowledged
opportunities for generators to reach inappropriate or
inaccurate hazardous waste determinations when acting in
good faith or otherwise. Webster's definition of "improper"
includes "not accordant with fact or right procedure" as
well as "not suited to the circumstances, design, or end,"
and therefore incorporates both elements of fact and law in
defining "improper" behavior. Management practices
contrary to law is certainly plausible in the refinery
industry. EPA's Office of Enforcement and Compliance
Assurance recently indicated the petroleum refinery industry
was one of three highest priority national sectors for
enforcement activities due to the "high noncompliance"
associated with this industry.

Third, in light of the documented practice of "air drying"
wastes as discussed above, reliance on the toxicity
characteristic in lieu of listing raises the specter of
refineries storing wastes on pads until such time as the
benzene volatilizes and the waste no longer exhibits a
hazardous waste characteristic. While such volatilization
should constitute treatment of an as generated hazardous
waste, the enforcement difficulties associated with
demonstrating the waste was hazardous after the fact, and
the complexity of enforcing the RCRA land disposal
restrictions on wastes that have been rendered nonhazardous
solely through evaporation, argue strongly for listing the
wastes as hazardous.

Fourth, the characteristic approach does not take into
account the high PAH content of some refinery wastes. Like
the groundwater modeling in the instant rulemaking, the
toxicity characteristic concentration thresholds were
developed assuming no preexisting contamination that would
increase the risk associated with waste releases and/or
facilitate the transport of hazardous constituents, in
direct contrast to the gross contamination present at many
refinery sites. This inapplicability of characteristic
development assumptions to refinery sites, combined with the
ineffectiveness of the TCLP to measure PAH leachability
discussed above, and the lack of coverage in the TC of the
relevant PAHs, would inappropriately result in the
management of wastes containing high PAH concentrations
outside of the Subtitle C regulatory program.

Fifth, by listing the wastes as hazardous, EPA can encourage
pollution prevention activities associated with refinery
waste management. A hazardous waste listing can bring
refinery wastes under a variety of state and federal
pollution prevention, waste minimization, and reporting
requirements, which could trigger careful scrutiny of the
way the wastes are generated and managed. Unfortunately,
while it is incumbent upon EPA to consider the source
reduction benefits of a hazardous waste listing as part of
this rulemaking, EPA simply lists waste minimization
practices applicable to refinery wastes. This
lackadaisical approach toward pollution prevention is
particularly disappointing given EPA's waste minimization
policy. (EDF, 00006, pg 45)

Response: Responses to the above comments are as follows:

This modeling is technically flawed because (1) it assumes
that TCLP is an accurate and consistent indicator of benzene
availability,

See Response to Comments 6 and 7 in Section I.C.1. The
Agency believes that the TCLP data are appropriate and are
reasonable indicators of benzene availability for these
wastes. 

(2) Because the approach is based on the unsupported
assumption that all wastes exhibiting the toxicity
characteristic for either benzene or arsenic are properly
managed as hazardous wastes,

In regard to the commenter's criticisms of TC cap modeling,
EPA notes that it conducted this analysis for crude oil tank
sludge, spent hydrotreating catalyst, spent hydrorefining
catalyst, and unleaded tank sludge. EPA is finalizing its
decision to list all but one of the above wastes, and notes
that the TC cap risk results for unleaded tank sludge are
not significantly different than the risk results for the
non-TC cap analysis (see Table 5.1 of Supplemental
Background Document for Groundwater Pathway Risk Analysis
(1997) and Tables 5.2 and 5.3 of the Additional Groundwater
Pathway Risk Analyses, Supplemental Background Document
(1998).
Therefore, the commenter's criticisms regarding the TC cap
analysis are moot. 

(3) Refineries' use of "air drying" volatilizes benzene.
EPA responds to the commenter's concerns regarding air
drying in NODA Section I.C.1, comment 1.

(4) The characteristic approach does not take into account
the high PAH content of some refinery wastes and would
underestimate the total risk associate with a particular
waste.

EPA responds to the commenter's concerns regarding the
effectiveness of the TCLP towards PAH containing wastes in
NODA Section I.C.1 Comment 7. However, EPA agrees that the
TC will not control risks from PAHs because PAHs are not TC
constituents.

(5) By listing the wastes as hazardous, EPA can encourage
pollution prevention activities associated with refinery
waste management.

EPA agrees with the commenter that listing wastes as
hazardous provides financial incentives to refineries to
minimize the quantity of waste generation. EPA disagrees
that it has a "lackadaisical" approach towards waste
minimization, and instead believes that a critical component
of waste minimization is communication. In this regard, EPA
has published an inventory of waste minimization practices
used for the listed wastes and other refinery wastes (see
"Waste Minimization for Selected Residuals in the Petroleum
Refining Industry," F-95-PRLP-S0064).

Comment 2: EPA Incorrectly Evaluated High-End TC-Capped
Risks from Landfilling

In its revised groundwater risk assessment for landfilling
of spent catalysts, EPA appropriately acknowledged that TCLP
measurements that exceeded the toxicity characteristic (TC)
for benzene and arsenic should not be included in the
evaluation of potential risks. Residuals containing these
elevated concentrations are currently, and will continue to
be, managed in hazardous landfills and thus should not be
included in the calculation of the average constituent
concentrations. Although EPA's intention to remove the TCLP
concentration data exceeding the TC is appropriate, the
methodology used by EPA in the calculation of revised TCLP
concentrations is flawed. Instead of either removing these
concentrations or substituting the TC cap value, EPA used
the TC cap value as the TCLP concentration when the average
and maximum values proved to be greater than the TC cap. In
essence, this approach causes the TCLP value to be a third
high-end parameter for spent hydrotreating catalyst, and
causes the waste concentration value to be greater even than
the maximum reported value for spent hydrorefining catalyst.
This approach is also inconsistent with the Monte Carlo
analysis, where EPA used the original TCLP data,
substituting the TC-capped value for individual values that
exceeded the TC. Using the approach applied by EPA in the
Monte Carlo analysis, API has calculated that the average
TCLP concentrations decreased to 60 percent of the TC cap,
as shown in Table 1. (API, 00009)

 Table 1. Revised TC Cap Waste Concentration for COTS and
 Spent Catalysts

Crude Oil Tank Sediment Benzene TCLP Data


Sample Benzene Concentration TC
Cappeda Benzene
 (mg/L) Concentration (mg/L)


R6B-CS-01 1.7 0.5
R8C-CS-01 1.6 0.5
R4B-CS-01 0.13 0.13
R10-CS-01 0.5 0.5
R19-CS-01 0.032 0.032
R22-CS-01 0.05 0.05 



Median 0.32 0.32
Value used in RA 0.68 0.5 
Average 0.67 0.29


Hydrotreating Catalyst Benzene TCLP Data


 Benzene Concentration TC Cappeda Benzene
Sample (mg/L) Concentration (mg/L)


R1-TC-01 39 0.5
R8A-TC-01 0.17 0.17
R11-TC-01 3.7 0.5
R3B-TC-01 0.048 0.048
R18-TC-01 4.2 0.5
R22-TC-01 0.25 0.25 



Median 1.98 0.38
Value Used in RA 7.90 0.50
Average 7.89 0.33


Hydrorefining Catalyst Benzene TCLP Data


 Benzene TC Cappeda Arsenic TC
 Concentration Benzene Concentration Cappeda 
Arsenic
Sample (mg/L) Concentration (mg/L) 
Concentration
 (mg/L) (mg/L)

R5-TC-01 0.1 0.1 0.23 0.23
R7B-RC-01 4.2 0.5 34 5
R21-RC-01 0.16 0.16 6.9 5



Median 0.16 0.16 6.90 5.00
Value
Used in RA 1.49 0.50 13.71 5.00

Average 1.49 0.25 13.71 3.41


Notes:
a: TC Cap substituted for values greater than the cap.
Revised average TCLP value in bold.
TC cap for benzene = 0.5 mg/L
TC Cap for arsenic = 5.0 mg/L
(API, 00009)

Response: The Agency does not completely agree with the
commenter on this issue. If some samples of a particular
waste stream have been shown to meet or exceed the TC rule
limit, then a conservative TC Capped analysis will include
the possibility that some of that waste disposed in Subtitle
D landfills will have leachate levels as high as 99% of the
TC limit. Therefore, the Agency does not believe that TCLP
data above the TC Rule value should simply be eliminated. 
Rather the data should be treated as it was in the Monte
Carlo Analysis.

Furthermore, EPA notes that even if the Agency used the TC-
capped input values suggested by the commenter's approach,
these values would be lowered for benzene by only 42% (crude
oil sediment), 34% (hydrotreating catalyst), and 50%
(hydrorefining catalyst). Because a decrease in the TCLP
input to the model for these wastes did not result in a
proportionate decrease in the level of benzene projected at
the receptor well (e.g., the decrease is less as shown by
the differences in the central tendency modeling results for
crude oil sediment using the average TCLP data versus the
TC-capped level), the impact of using the commenter's
approach would be minimal (i.e., decreases would be well
below a 50% decrease). Concerning the catalysts, the impact
of TC-capping for the arsenic risks for the hydrorefining
catalyst is negligible, showing that the modeling results
are not impacted significantly by small changes in the
arsenic input data. (This lack of sensitivity to arsenic
input data is due to the relatively slow movement of this
constituent via groundwater from the landfill to the
receptor well). The arsenic risks for hydrotreating
catalysts do not change under any TC-capping assumption
because none of the samples exceeded the TC level for
arsenic. As such, the risks would remain the same as the
uncapped analysis.

Comment 3: EPA Incorrectly Evaluated High-End TC-Capped
Risks from Landfilling

In its revised groundwater risk assessment for landfilling
of spent catalysts, EPA appropriately acknowledged that TCLP
measurements that exceeded the toxicity characteristic (TC)
for benzene and arsenic should not be included in the
evaluation of potential risks. Residuals containing these
elevated concentrations are currently, and will continue to
be, managed in hazardous landfills and thus should not be
included in the calculation of the average constituent
concentrations. Although EPA's intention to remove the TCLP
concentration data exceeding the TC is appropriate, the
methodology used by EPA in the calculation of revised TCLP
concentrations is flawed. Instead of either removing these
concentrations or substituting the TC cap value, EPA used
the TC cap value as the TCLP concentration when the average
and maximum values proved to be greater than the TC cap. In
essence, this approach causes the TCLP value to be a third
high-end parameter for spent hydrotreating catalyst, and
causes the waste concentration value to be greater even than
the maximum reported value for spent hydrorefining catalyst.
This approach is also inconsistent with the Monte Carlo
analysis, where EPA used the original TCLP data,
substituting the TC-capped value for individual values that
exceeded the TC. (Phillips, 00014)

Response: See Response to Comment 2 above.

I.A.5. Waste-Specific Comments 

Comment 1: Crude Oil Storage Tank Sludge

While EPA proposed a negative listing determination (at the
behest of OMB), crude oil storage tank sludge warrants
listing as a hazardous waste. After correcting only a few
of the flaws in EPA's groundwater modeling methodology, KGS
demonstrated this waste poses a human health risk of at
least 1.6x10-4 via the groundwater pathway, substantially
above EPA's presumptive listing risk level.

Significantly, the KGS modeling understates the risk posed
by crude oil storage tank sludge because the KGS modeling
revisions do not reflect:

1. The true leachability of the waste since the modeled
TCLP value still assumes no primary leachate generation and
no free-phased contaminant migration, and thus understates
actual benzene availability; 

2. High-end waste volumes that incorporate high-end
landfill active life duration, since all volumes were
derived using only an average landfill life assumption;

3. Appropriate offsite median and high-end landfill areas; 

4. The contribution of pre-existing contamination at
refinery sites to receptor well contamination; 

5. Risks posed by contaminants other than benzene in the
waste. 

The average total concentration of benzene in this waste
exceeds the comparable concentration of benzene in F037 and
F038 that caused those wastes to be listed in 1990. 
Similarly, the benzo(a)pyrene concentration in crude oil
storage tank sludge exceeds the comparable concentration in
F038 and K145 which caused those wastes to be listed in 1990
and 1992. And the average total concentration of
indeno(1,2,3-cd)pyrene exceeds comparable concentrations in
K145 which caused that waste to be listed in 1992.

EPA's proposed negative listing determination is also
unjustified because the Agency has not evaluated the risks
posed by management practices such as landfill daily cover,
road spreading, and other uses constituting disposal. The
NODA LTU Risk Assessment is not an adequate surrogate risk
evaluation because the volume of waste modeled, coupled with
other modeling shortcomings, rendered that assessment
inapplicable to most plausible mismanagement scenarios.
(EDF, 00006)

Response: EPA responds to the five ground water modeling
issues in the above comments in other sections of this
response to comments. Specifically, EPA presents a
"roadmap" of where these five issues are discussed in
response to comment 3, Section I. 

The commenter also compares the concentration of benzene and
PAHs between crude oil tank sludge and currently listed
wastes. EPA does not agree with the commenter's comparisons
because, in general, listing decisions are based on multiple
reasons including, but not limited to, constituent
concentrations. EPA recognizes that crude oil tank sediment
may contain concentrations of some constituents comparable
to previously listed wastes, including the F037 and F038
refinery residuals. However, direct comparison of these
concentrations to previous listing benchmarks is not an
adequate basis for listing. Listing determinations consider
many factors beyond the concentrations of constituents in a
waste, including the waste volume, constituent mobility,
management practices, damage cases, other regulatory
controls, etc. (see 40 CFR 261.11). Over the years since
the rule cited by the commenter was promulgated, EPA's risk
assessment process has evolved, due in part to public
comments, EPA policy and research developments, the review
of the Science Advisory Board, and others. The Agency has
developed a more sophisticated set of risk assessment tools
than were available for listing determinations in 1990. As
a result, EPA believes that it is better able to measure and
predict risk. Therefore EPA does not agree with the
commenter's implication that wastes in the scope of this
rulemaking should be listed if constituent concentrations
exceed levels in previously listed wastes. In any case, EPA
notes that it has decided to list crude oil tank sediment as
hazardous, making the commenter's argument that EPA was
inconsistent moot.

Section V.C of this NODA comment response presents comments
and responses regarding risks posed by waste management
practices cited by the commenter, including landfill daily
cover and road spreading.

Comment 2: CSO Sludge

While EPA proposed to list this waste as hazardous, the
Agency also sought comment on whether the listing should be
limited to land treatment of the waste. As demonstrated by
the KGS modeling, the purportedly low risks attributed to
EPA's landfill modeling is a function of the ineffectiveness
of the TCLP to leach PAHs from this oily waste. Therefore,
the waste should be listed as hazardous without limitation.

CSO sludge contains very high percentages of oil and grease,
and when not inappropriately air dried or mixed with cement
kiln dust prior to sampling, the oil "seeps out when
squeezed". It has all the properties of wastes for which
EPA and its contractor previously found the TCLP grossly
ineffective, particularly for PAHs.

According to the KGS modeling, if only 0.008% of the
benz(a)anthracene or 0.005% of the chrysene in the average
CSO sample leaches from the waste, the resulting risk in the
receptor well equals 10-4, EPA's presumptive listing risk
level. When the combined risks of these chemicals are
considered, the required leaching values are even lower. 
Moreover, the KGS modeling does not reflect:

1. High-end waste volumes that incorporate high-end
landfill active life duration, since all volumes were
derived using only an average landfill life assumption;

2. The contribution of pre-existing contamination at
refinery sites to receptor well contamination; 

3. The potential for facilitated PAH transport at refinery
sites due to the cosolvency effects of oil and other
compounds in the landfill, and/or the presence of NAPLs in
the subsurface.

On the basis of EPA's previous positions regarding the
efficacy of the TCLP on oily wastes, EPA's contractor report
demonstrating the poor performance of the TCLP on PAHs in
oily wastes, EPA's data indicating CSO sludge contains high
percentages of oil and grease, and the potential for CSO
sludge to contain free liquid, it is more than plausible
that these wastes will leach PAHs at the extremely small
concentrations which pose a substantial risk to human health
and the environment. 

The average total concentration of chrysene in the CSO
residuals substantially exceeds the comparable
concentrations in F037, F038, K143, K144, and K145 that
caused those wastes to be listed in 1990 and 1992. 
Similarly, the average total concentration of benzo(a)pyrene
in the CSO residuals substantially exceeds the comparable
concentrations in F038, K143, K144, and K145 that caused
those wastes to be listed in 1990 and 1992. In addition,
concentrations of benz(a)anthracene and benzofluoranthene
(total) in the CSO residuals exceed comparable
concentrations in K143, K144, and K145 that caused those
wastes to be listed in 1992. And the concentration of
indeno(1,2,3-cd)pyrene in the CSO residuals exceeds the
comparable concentration in K145 which caused that waste to
be listed in 1992. (EDF, 00006)

Response: EPA responds to each of the commenters concerns
in other sections of this response to comment document. The
commenter's concerns regarding the ineffectiveness of the
TCLP are discussed in comment 7 of Section I.C.1, concerns
regarding sampling and the appropriateness of using samples
that underwent treatment is discussed in comment 1 of
Section I.C.1, leaching of PAHs is discussed in comment 7 of
Section I.C.1, and a comment response "roadmap" for the
three modeling issues is presented in Section I, comment 3. 
Finally, for the reasons presented in Section I.A.5 comment
1 (immediately above), EPA believes it is inappropriate to
compare constituent levels in CSO sludge to constituent
levels in previously listed wastes as a basis for a listing
decision.

Finally, EPA notes that the final listing for CSO tank
sediment will not incorporate an conditional limitations
(e.g., disposal as nonhazardous in a landfill would not be
allowed). Therefore, the commenter's concerns about the
potential risks from landfilling of this waste will be
addressed in any case.

Comment 3: Unleaded Gasoline Storage Tank Sludge

While EPA proposed a negative listing determination for this
waste, unleaded gasoline storage tank sludge warrants
listing as a hazardous waste. After correcting only a few
of the flaws in EPA's groundwater modeling methodology, KGS
demonstrated this waste poses a human health risk of at
least 8.8x10-5 via the groundwater pathway.

Significantly, the KGS modeling understates the risk posed
by unleaded gasoline storage tank sludge because the KGS
modeling revisions do not reflect:

1. The true leachability of the waste since the modeled
TCLP value still assumes no primary leachate generation and
no free-phased contaminant migration, and thus understates
actual benzene availability; 

2. High-end waste volumes that incorporate high-end
landfill active life duration, since all volumes were
derived using only an average landfill life assumption;

3. Appropriate offsite median and high-end landfill areas; 

4. The contribution of pre-existing contamination at
refinery sites to receptor well contamination; 

5. Risks posed by contaminants other than benzene in the
waste; and

6. A comprehensive set of two high-end sensitivity analyses
for the revised modeling parameters.

The average total concentration of benzene in unleaded
gasoline storage tank sludge exceeds the comparable
concentrations in F037 and F038 that caused those wastes to
be listed in 1990.

Given the risk levels are at the high-end of the 10-4 to 10-6
risk range, unleaded gasoline storage tank sludge warrants
listing as a hazardous waste based upon the factors EPA
considers under its listing determination policy when risks
from improper waste management fall within that range. 
First, the waste characterization is extremely uncertain
because EPA's sampling consists of two only valid samples
(the third was inappropriately air dried), and the modeled
leaching values are still based upon the ineffective TCLP
with no primary leachate generation for wastes containing
"one inch of free liquid". Second, even the KGS modeling
results are uncertain because it may significantly
underestimate potential risks for the reasons discussed
above. Third, the risks posed by the co-disposal of this
waste and other refinery wastes are also significant. 
Fourth, other regulatory programs will not address the risks
posed by the mismanagement of these wastes.

EPA's proposed negative listing determination is also
unjustified because the Agency has not evaluated the risks
posed by management practices such as landfill daily cover,
road spreading, and other potential uses constituting
disposal. The NODA LTU Risk Assessment is not an adequate
surrogate risk evaluation because the volume of waste
modeled, coupled with other modeling shortcomings, rendered
that assessment inapplicable to most plausible mismanagement
scenarios. (EDF, 00006)

Response: EPA responds to the KGS modeling results for this
waste in comment 2 of Section I. EPA also notes that the
total oil and grease levels in the available samples for
this specific waste were well below 1 percent. Thus, the
commenter's concern about problems with oily waste are
clearly unfounded for this waste. 

EPA disagrees with the commenter's assertion that
groundwater risks require listing of this waste. For the
reasons given elsewhere (as noted above) earlier in today's
notice, EPA does not agree with most of the changes
incorporated into the alternative groundwater modeling. 
However the Agency did modify its modeling analysis to
reflect comments on: increased active life of landfills,
increased unit area corresponding to municipal landfills,
and consideration of noningestion routes of exposure to
groundwater by receptors (e.g., via inhalation during
showering). EPA also performed a full sensitivity analysis,
which had not been done for the NODA analysis. These
changes resulted in a somewhat higher groundwater risk for
this waste (3E-05; see NODA Table 1) than previously
calculated. While this risk is of some concern to the
Agency, EPA has decided not to list this waste after
considering other factors. First, the waste is lacking the
characteristics shown by other wastes that EPA decided to
list in this rule. It does not present the additional risk
factors due to arsenic and pyrophoricity exhibited by the
spent hydrotreating and hydrorefining catalysts, nor does it
show the high oil and PAH content found in the CSO and crude
oil tank sediment. In addition, the unleaded gasoline
sediment appears to consist largely of tank scale and rust,
as evidenced by the high level of iron found in EPA's
samples (average level of 41% measured as elemental iron). 
The relatively small annual volume generated (3,583 MT) and
sent to landfills (22 MT average per facility) are
significantly lower than volumes of the other storage tank
sediments, e.g., crude oil tank sediment (generated, 22,017,
average landfilled, 123 MT). Finally, EPA notes that recent
Clean Air Act regulations will result in the decrease of
benzene in gasoline (see Reformulated Gasoline Rule,
February 16, 1994; 59 FR 7716). EPA also believes that the
groundwater risk results suggest that its analysis was quite
conservative, i.e., the DAF corresponding to the high-end
risk for off-site landfills was only 4.4. Thus, EPA has
decided not to list this waste.

 EPA believes it is inappropriate to compare constituent
levels in unleaded gasoline tank sediment to constituent
levels in previously listed wastes as a basis for a listing
decision as discussed in Section I.A.5, comment 1. EPA
addresses the commenters concerns regarding sampling in
Section I.C.1, comment 1. Comments regarding EPA's approach
to assessing co-disposal are in Section I.B.3. 

Section V.C of this NODA comment response presents comments
and responses regarding risks posed by waste management
practices cited by the commenter, including landfill daily
cover and road spreading. EPA also notes that, in this
case, no refineries reported use of unleaded gasoline tank
sediment as landfill cover or in road spreading. The Agency
has no data supporting these management scenarios and
therefore does not see the need to model this pathway. 
Furthermore, EPA believes that nongroundwater risks are
unlikely to be significant for this waste under any
scenario, because unleaded gasoline tank sediment has none
of the carcinogenic PAHs that were of concern for other
wastes. 

Finally, the risks posed by mismanagement of this waste has
been assessed in the proposed rule, and on the basis of
these results (and other listing criteria in 40 CFR Section
261), EPA has decided to list or not list specific refinery
wastes; therefore EPA believes the commenter's concerns
regarding the absence of regulatory programs for waste
mismanagement are fully addressed by today's listing
decisions.

Comment 4: Off-Spec Products and Fines from Thermal
Processes

While EPA proposed a negative listing determination for this
waste, off-spec products and fines warrants listing as a
hazardous waste for two separate but equally important
reasons. First, when this waste is landfilled, the KGS
modeling indicates the risk posed by the groundwater pathway
is at least 5x10-5, after correcting only some of the flaws
in EPA's modeling methodology.

Given the risk levels are at the high-end of the 10-4 to 10-6
risk range, off-spec products and fines warrants listing as
a hazardous waste based upon the factors EPA considers under
its listing determination policy when risks from improper
waste management fall within that range. First, the waste
characterization is extremely uncertain because the modeled
leaching values are still based upon the ineffective TCLP. 
Second, even the KGS modeling results are uncertain because
it may significantly underestimate potential risks for the
reasons discussed below. Third, the risks posed by the co-
disposal of this waste and other refinery wastes are also
significant. Fourth, other regulatory programs will not
address the risks posed by the mismanagement of these
wastes. 

In addition, KGS determined that if only 0.01% of the
benz(a)anthracene or 0.5% of the chrysene in the average
off-spec products and fines sample leached from the waste,
the resulting risk via the groundwater pathway would be
10-4, EPA's presumptive risk level for listing hazardous
wastes. When the combined risks of these chemicals are
considered, the required leaching values are even lower. 
Moreover, the KGS modeling does not reflect:

1. High-end waste volumes that incorporate high-end
landfill active life duration, since all volumes were
derived using only an average landfill life assumption;

2. A comprehensive set of two high-end sensitivity analyses
for the revised modeling parameters, and associated high-end
offsite volumes consistent with Table B.2 of the NODA
Groundwater Risk Assessment and Section II.E.1 of these
comments;

3. The contribution of pre-existing contamination at
refinery sites to receptor well contamination; 

4. The potential for facilitated PAH transport at refinery
sites due to the cosolvency effects of oil and other
compounds in the landfill, and/or the presence of NAPLs in
the subsurface.

On the basis of EPA's previous positions regarding the
efficacy of the TCLP on oily wastes, EPA's contractor report
demonstrating the poor performance of the TCLP on PAHs in
oily wastes, and EPA's data indicating off-spec products and
fines contains high percentages of oil and grease, it is
more than plausible that these wastes will leach PAHs at the
extremely small concentrations which pose a substantial risk
to human health and the environment. 

Second, off-spec products and fines warrant hazardous waste
listing when placed on piles for potential use as a fuel
(with petroleum coke), irrespective of whether EPA considers
this material a coproduct when managed in this fashion. The
only meaningful risk assessment associated with this
practice to date (performed in 1995) indicated risks
exceeding 1x10-3 to nearby human receptors, and this
evaluation was based on waste volumes only 1/7 of the values
associated with high-end pile usage. The NODA LTU Risk
Assessment does not alter these previous results because the
quantities of waste modeled in the NODA assessment were more
than several orders of magnitude lower than the relevant
pile volumes, among other shortcomings discussed in Section
III of these comments.

Even assuming arguendo the off-spec products and fines are
coproducts when stored with petroleum coke, EPA must still
render a listing determination for this residual when stored
on piles. Pursuant to 40 CFR 261.33, EPA lists a variety of
products, including off-specification products, when
discarded or intended to be discarded. Therefore, if the
off-spec products and fines are not actually reused when
placed on the pile, because the residual blows off the pile
or migrates via runoff, such off-spec products and fines
would be regulated as hazardous wastes.

Pursuant to the Consent Decree in EDF v. Browner, EPA is
required to issue a listing determination for off-spec
products and fines. Given that an estimated 169,986 MT of
the total 194,262 MT (87%) off-spec products and fines
generated in 1992 was placed in piles and subject to
discard, and that such discard presents a substantial risk
to human health and the environment based upon the
assessments conducted to date, the required listing
determination must include a decision as to whether off-spec
products and fines warrants listing pursuant to 40 CFR
261.33.

Finally, EPA's proposed negative listing determination is
inappropriate because the Agency has not considered the
risks posed by managing off-spec products and fines in
surface impoundments. As discussed above in Section IV of
the [EDF] comments, EPA has documented the use of surface
impoundments for this waste, yet EPA has failed to evaluate
this plausible mismanagement scenario. (EDF, 00006)

Response: Many of the commenter's concerns are discussed in
detail in other sections of this background document. EPA
responds to the KGS modeling results for this waste in
comment 2 of Section I.A. The effectiveness of the TCLP and
PAH leaching is discussed in comment 7 of Section I.C.1. 
Comments regarding EPA's approach to assessing co-disposal
are in Section I.B.3. EPA responds to the KGS modeling
results for this waste in comment 7 of Section I.C.1 and
presents a comment response "roadmap" for the four modeling
issues in Section I, comment 3. The commenter's concerns
regarding the placement of this waste in surface
impoundments is discussed in Section IV.C in response to
comment 3.

Regarding the commenters' criticism of EPA's use of TCLP
results as input values to the landfill groundwater modeling
for this material because it is "oily", the Agency points
out that off-specification product and fines are generally
not oily. The Agency conducted total oil and grease
analyses on 4 samples and the average level of oil and
grease (measured as Total Oil and Grease, i.e., not truly
"free" oil) was 2 percent (3 samples were below 1 percent). 
Furthermore, the data from the 3007 Questionnaire show that
the typical material has relatively low oil content (90th%
value was 5%). Therefore, EPA believes that the use of the
TCLP was valid.

With regards to commenter concern over free-phase flow of
contaminants from off-specification product and fines due to
oil content, the Agency concluded that free phase flow is
unlikely with these residuals as discussed earlier in
today's notice. It is particularly important to note that
none of the six off-spec product and fines from thermal
processes samples exhibited a separate oil phase, and that
the measured and oil content was low, as noted above.

For the reasons noted elsewhere in this document (and
referenced above), EPA does not agree with most of these
changes employed in the alternative KGS analysis. The
Agency did modify its modeling analysis to reflect
suggestions on increased active life of landfills, increased
unit area corresponding to municipal landfills, and
consideration of noningestion routes of exposure to
groundwater by receptors (e.g., via inhalation during
showering). These changes tended to increase the projection
well concentration of constituents. However, EPA notes that
the risk results presented in the NODA was in error because
it was based on an erroneous health-based number
(carcinogenic risk factor) for the PAH, benz(a)anthracene
(BaA). EPA had used the correct number in the
nongroundwater risk analysis used to estimate releases from
land treatment units, as noted in the 1995 background
document (Assessment of Risks from the Management of
Petroleum Refining Wastes: Background Document, 1995), but
inadvertently did not use the correct number in the
groundwater analysis. Use of the correct health-based
number results in a 30-fold decrease in the risks calculated
from the well concentration of BaA. Using the revised
groundwater model inputs (active life and area) and the
correct health-based number yields a high-end risks of 5E-7
and 2E-6, and Monte Carlo risks are 9E-7 and 1E-6 (see
Additional Groundwater Pathway Analysis, 1998). 

Furthermore, as EPA described in the NODA, the estimated
groundwater risks were based entirely on one chemical (BaA)
that was detected in only one out of six TCLP samples, at a
level 8-fold below the quantitation limit. The risk of
2E-06 was calculated using this one TCLP input, along with two
other high-end parameters in the sensitivity analysis. EPA
also calculated a risk of 5E-07 (based on the correct
health-based number) by assuming that this one detected TCLP
level should reflect one of the high-end parameters, and
then running the sensitivity analysis to calculate risk
based on one other high-end parameter. While EPA believes
it is probably more appropriate to assign the one detected
value to be one of the high-end parameters, even the high-
end groundwater risk of 1E-06 clearly supports a decision
not to list off-specification product and fines. 

Concerning the placement of coke fines on coke piles, EPA
considers this to be co-management of product with larger
coke particles, and not waste. EPA discussed this issue in
the NODA, and noted that only particle size distinguishes
coke fines from other coke product. The majority of coke is
removed from the coker by hydraulic drilling, and coke fines
are generated as smaller pieces of coke during this process. 
In addition, EPA explained there is a jurisdictional
distinction between coke fines produced from non-hazardous
materials and coke fines produced from hazardous wastes
(waste-derived fines). Fines generated from non-hazardous
materials are simply coke product, as would be expected
since they are produced from the same coking drum. In the
case of waste-derived fines, so long as the fines are
legitimate coke product, they are exempt from RCRA
regulation unless the material exhibits a characteristic as
provided in 40 CFR 261.6(a)(3)(v). (See also RCRA section
3004(q)(2)(A)). EPA had no information that waste-derived
coke fails any hazardous waste characteristic. The Agency
invited comment or data to the contrary but received none. 

The commenter is attempting to use a bounding analysis EPA
undertook for nongroundwater risks for coke fines disposed
in landfills as an indication that air releases from piles
containing this material would present similar risks. In
response, EPA first notes that bounding estimates are used
as an initial screening estimate that overestimates the
exposure or dose for the purpose of screening out exposures
of little concern. The purpose of the bounding analysis is
simply to determine what pathways and scenarios require
further evaluation and does not represent an assessment of
risks. The bounding analysis included worst-case
assumptions (no cover or dust suppression, highest
constituent levels, largest waste volumes and landfill area,
worst climate, etc). Furthermore, the levels near 1E-3
arose from indirect pathways (ingestion of beef, dairy,
fish, and plant products); the direct pathway of soil
ingestion, even in the bounding analysis was on the order of
1E-06. Most importantly, the biotransfer factors used in
the bounding analysis for beef, dairy, and plant indirect
paths have been determined to overestimate risks by at least
two orders of magnitude; likewise the apparent problem from
mercury was also traced to an error in units for the
bioaccumulation factor used. Thus, EPA believes that the
bounding analysis was flawed and grossly overestimated
risks.

EPA notes that the subsequent high-end analyses for
nongroundwater risks from landfill disposal of off-spec
product and fines did not show significant risk. While the
high-end analysis included the assumption of daily cover for
the landfill, and thus may not be a the best surrogate for
air releases from piles, the scenario did consider windblown
dust from on-site roads and particulate release caused by
traffic (i.e., dump trucks), loading, unloading, etc. The
high-end analysis showed risks no higher than 2x10-6 for any
receptor (see U.S. EPA, Assessment of Risks from the
Management of Petroleum Refining Wastes Background Document
(F-95-PRLP-S0006), page 10-3). Therefore, some of the
possible release mechanisms that could occur in a waste pile
scenario (e.g., unloading/loading, traffic) were addressed
in the risk assessment supporting the proposal and the
pathway was not significant.

EPA also points out that some important characteristics of
the coke pile and details of management practices used by
refineries would tend to mitigate potential risks. The
piles are not comprised simply of coke fines, but are
mixtures of much larger pieces of coke product that are
drilled from coker units; the larger chunks of coke would
make up the bulk of the pile. Furthermore, coke is drilled
out of the coker approximately once a day with hydraulic
drills, thus new wet coke/fines from drilling are added to
the coke pile, making air releases of dry particulates less
likely. EPA has also found that coke piles are managed
using various practices to control release of dust,
including: (a) contained product storage areas; (b) dust-
suppression water spray systems; covered conveyor systems;
and, (d) direct loading from coke-drums into railcars (see
NODA response to comment document for a summary of these
practices). In addition, EPA expects that particulate
releases from these areas would be controlled by Federal,
State, or local air regulations and permit programs.

Finally, EPA disagrees with the commenter's argument that,
pursuant to the Consent Decree in EDF v. Browner, EPA is
required to issue a listing determination for off-spec
products and fines that must include a decision as to
whether off-spec products and fines warrants listing
pursuant to 40 CFR 261.33. The Agency has, in fact, made a
listing decision for the off-spec product and fines that are
known to be discarded by refineries, i.e., the volumes of
wastes that are disposed. EPA believes it has fulfilled the
requirements of the Consent Decree. Furthermore, at this
time the Agency has no valid assessment that indicates these
wastes present a "substantial risk", and believes that the
available data suggest otherwise.

Comment 5: EPA Has Dealt Reasonably With The Issue Of Risks
Associated With the Disposal of Off-Specification Coke and
Fines

EPA proposed not to list off-specification coke and fines,
in part because so much of this material is sold as a
product. See 62 Fed. Reg. 16750 (April 8, 1997). As
discussed elsewhere in these comments, EPA is correct that
off-specification coke and fines sold as product are not
wastes and are beyond EPA's RCRA jurisdiction. See id.

As to coke and fines that are disposed of, EPA's original
risk assessment projected high-end individual risk of 1 x
10-5, and its revised risk assessments projected individual
risks varying from 5 x 10-6 to 2 x 10-5, depending upon the
method used. Id. at 16751. Although the projected risks
"are within the Agency's initial risk level of concern,"
id., the Agency determined that the risks are, in fact, not
significant.

The Agency reasoned that (1) the risk estimates are
unrealistically high, because they are based on one
constituent (benz(a)anthracene) that was detected in only
one of six samples, and even then, at a level 8-fold below
the quantitation limit; (2) benz(a)anthracene is not very
soluble in water, so its aqueous concentration may be
expected to be low; and (3) benz(a)anthracene is not very
mobile in groundwater. Id. API agrees with and supports
this very reasonable approach to dealing with individual
risk estimates that are on or near the borderline of EPA's
range of risk levels of concern, especially under
circumstances that indicate the projected risks are
inflated. Thus, EPA is fully justified in finding that the
listing of off-specification coke and fines is not
warranted. (API, 00009, pg 17)

Response: The Agency acknowledges the support of the
commenter.

Comment 6: HF Alkylation Sludge

While EPA proposed a negative listing determination for this
waste, HF alkylation sludge warrants listing as a hazardous
waste. After correcting only a few of the flaws in EPA's
groundwater modeling methodology, KGS demonstrated this
waste poses a human health risk of at least 2.3x10-5 via the
groundwater pathway.

Significantly, the KGS modeling understates the risk posed
by HF alkylation sludge because the KGS modeling revisions
do not reflect:

1. The true leachability of the waste since the modeled
TCLP value still assumes no primary leachate generation and
no free-phased contaminant migration, and thus understates
actual benzene availability; 

2. High-end waste volumes that incorporate high-end
landfill active life duration, since all volumes were
derived using only an average landfill life assumption;

3. Appropriate offsite median and high-end landfill areas; 

4. The contribution of pre-existing contamination at
refinery sites to receptor well contamination;

5. Risks posed by contaminants other than benzene in the
waste; and

6. A comprehensive set of two high-end sensitivity analyses
for the revised input parameters. 

Given the risk levels are at the middle of the 10-4 to 10-6
risk range, HF alkylation sludge warrants listing as a
hazardous waste based upon the factors EPA considers under
its listing determination policy when risks from improper
waste management fall within that range. First, the waste
characterization is extremely uncertain because the modeled
leaching values are still based upon the ineffective TCLP
with no primary leachate generation for wastes that are
"black and oily with a high liquid content", "yellow with a
consistency of wet oily sludge", and have a consistency of
"oil-in-water emulsion". 

Second, even the KGS modeling results are uncertain because
it may significantly underestimate potential risks for the
reasons discussed above. Third, the risks posed by the co-
disposal of this waste and other refinery wastes are also
significant. Fourth, other regulatory programs will not
address the risks posed by the mismanagement of these
wastes.

EPA's proposed negative listing determination is also
inappropriate because the Agency has not considered the
risks posed by managing HF alkylation sludge in surface
impoundments. EPA has documented the use of "pits" for this
waste, yet EPA has failed to evaluate this plausible
mismanagement scenario.

Response: EPA responds to each of the commenter's concerns
in other sections of this response to comment document. EPA
responds to the KGS modeling results in comment 2 of Section
I.A. EPA presents a "roadmap" of the six enumerated issues
in response to comment 2 of Section I.A. EPA disagrees
that listing of this waste is appropriate. For the reasons
noted in other sections in this document, EPA does not agree
with most of the changes incorporated into the alternative
groundwater modeling, however the Agency did modify its
modeling analysis to reflect comments on: increased active
life of landfills, increased unit area corresponding to
municipal landfills, and consideration of noningestion
routes of exposure to groundwater by receptors (e.g., via
inhalation during showering). These changes resulted in a
somewhat higher groundwater risk for this waste (1 x10-5;
see Additional Groundwater Pathway Analysis, 1998) than
previously calculated. While this risk is of some concern
to the Agency, EPA has decided not to list this waste after
considering other factors. Most importantly, the risk was
due to the presence of one constituent, benzene, that was
detected in only one of the five samples. Thus, the
constituent does not appear to appear frequently in this
wastes. Further, the level of benzene in this waste (0.076
mg/L average, 0.180 mg/L maximum) is considerably lower than
the other petroleum wastes EPA is listing in this rule based
on groundwater risks (e.g., for crude oil tank sediment the
average and maximum benzene TCLP levels were 0.68 and 1.7
respectively). EPA also believes that the groundwater risk
results suggest that its analysis was quite conservative,
i.e., the DAF corresponding to the high-end risk for off-
site landfills was only 2.8. Thus, EPA has decided not to
list this waste.

Comment 7: Hydrotreating/Hydrorefining Catalyst

EPA proposed to list these spent catalysts as hazardous
wastes. When EPA revises the NODA risk assessments to
correct the modeling flaws discussed throughout these
comments, the case for listing will be even more dramatic.

As discussed in Section II.J of this [EDF's] document, the
listing mechanism for these and other refinery wastes is
necessary and appropriate, notwithstanding the potential
reach of the toxicity characteristic. In this context,
listings would substantially improve the implementation and
enforcement of RCRA requirements as they apply to refinery
wastes. A characteristic-based approach for refinery wastes
is extremely problematic, due to the inconsistencies of the
TCLP on oily wastes, the acknowledged difficulties
associated with determining the validity of "knowledge-
based" hazardous waste determinations especially where TCLP
results may vary from one batch of the same wastes to the
next, the practice of air drying wastes thereby allowing
benzene to volatilize, and other management practices such
as mixing the waste with soil to dilute the benzene
concentration. The implementation and enforcement
advantages of a listing outweigh whatever disadvantages EPA
perceives in listing the wastes as hazardous. (EDF, 00006,
pg 76)

Response: EPA acknowledges the commenter's support of EPA's
decision to finalize the listing of spent hydrotreating and
spent hydrorefining catalysts.

Comment 8: EPA Should Not List Hydrotreating Catalyst

EPA's revised risk assessment in the NODA for landfilling
hytrotreating catalysts clearly indicates that hydrotreating
catalyst should not be listed as a hazardous waste. The
individual risks calculated are within the discretionary
range, even with the conservative assumptions employed. 
Similar risk levels for landfilling crude oil tank sediment
were not determined by EPA to warrant listing. Moreover,
the Monte Carlo analysis, which is the appropriate analysis
on which to base a decision, has a risk finding that would
support a no list decision. Such a decision can be further
supported by EPA's evaluation of population risks which
predicts only three cases of cancer in 100,000 years, a
clearly negligible result. (Mobil, 00002, pg 2)

Response: EPA disagrees with the commenter. EPA continues
to believe that the risks from the high-end analysis fully
support listing this waste, and the somewhat higher revised
groundwater risks further support EPA's decision. As a
result of the revised risk analysis, the off-site landfill
groundwater risks increased further. As shown in Table
IV-2, the revised off-site risks for hydrotreating catalyst are
1E-04 for benzene and 8E-05 for arsenic; the TC-capped
results for this waste showed lower risk for benzene (3E-05),
but arsenic was unchanged. Similarly, the revised off-
site risks for hydrorefining catalyst are 7E-05 for benzene
and 6E-04 for arsenic, and the TC-capped analysis for this
wastes lowered the benzene risks (3E-05) but had no impact
on arsenic risk. The revised Monte Carlo risks for
hydrotreating catalyst (benzene 3E-5, arsenic 2E-5 at the
95th percentile) and hydrorefining catalyst (benzene 2E-5,
arsenic 4E-4 at the 95th percentile) were somewhat lower,
but still well above the listing benchmark of 1E-5. As in
the NODA analysis, the high-end and Monte Carlo risks for
arsenic were not lowered by the TC-capped analysis. While
the TC-capped risks for both catalysts were somewhat lower
in the high-end (both at 3E-5) and Monte Carlo analysis
(9E-6 and 8E-6 for the hydrotreating and hydrorefining risks
respectively), EPA believes that the overall results are
strongly supportive of listing both spent catalysts. Even
in the TC-capping results, both catalysts present risks in
off-site landfills that exceed 1E-5. Specifically, for both
hydrotreating and hydrorefining catalysts, the TC-capped
arsenic risks exceed 1E-5 for the Monte Carlo and high-end
evaluations, and the benzene risks exceed this benchmark in
the high-end evaluation and approaches this level in the
Monte Carlo analysis. 

 In addition to the groundwater risks posed by these
materials, the pyrophoric and self-heating nature of these
catalysts also support EPA's conclusion that these materials
present a substantial hazard. Therefore, after EPA
considered the risks posed by these materials, along with
the possibility that characteristically hazardous waste may
not always be handled as hazardous, the Agency has decided
to list hydrotreating and hydrorefining catalysts as
hazardous wastes.

EPA responds to comments on population risk in Section IV.B.

Comment 9: EPA's Record Now More Strongly Supports Its
Decision Not to List Eleven of the Fourteen Refinery
Residuals Considered for Listing

In its original proposal of November 20, 1995 (60 FR 57747),
EPA determined not to propose for listing crude oil storage
tank sediment, unleaded gasoline storage tank sediment, off-
specification product and fines from thermal processes,
catalyst from reforming, catalyst from sulfuric acid
alkylation, sludge from sulfuric acid alkylation, HF
alkylation sludge, spent caustic from liquid treating,
catalyst and fines from catalytic cracking, catalyst from
sulfur complex and H2S removal facilities, and sludge from
sulfur complex and H2S removal facilities. Some of these
residuals are used in ways that prevent them from being
solid wastes and are thereby inappropriate candidates for
listing. Others are solid wastes and EPA based its proposal
not to list these residuals on sound data and conservative
risk analysis. The NODA adds additional information to
support these "no list" decisions, with new analyses
evaluating co-disposal and additive risk scenarios that
found no basis to warrant listing. (Mobil, 00002, pg 2)

Response: EPA is finalizing its decision to not list all but
one of the above wastes (EPA is listing crude oil tank
sediment). EPA appreciates the commenter's support for its
no-list decisions.

Comment 10: The EPA's Decision to Not List 11 Residuals as
Hazardous Waste was Correct

Sun supports EPA's decision not to list the 11 residuals
originally proposed for non-listing. Although Sun agrees
that some re-evaluation of the listing process was needed,
the results of the re-evaluation did not justify changing
the listing decision on the 11 residuals. (Sun, 00008)

Response: EPA is finalizing its decision to not list all but
one of the above wastes (EPA is listing crude oil tank
sediment). EPA appreciates the commenter's support for its
no-list decisions.

Comment 11: As part of the NODA, EPA conducted several new
analyses, including evaluation of co-disposal and additive
risk scenarios. EPA's proposal not to list sludge from
H2SO4 alkylation catalyst from H2SO4 alkylation, crude oil
storage tank sludge, Claus catalyst and SCOT-like catalyst,
catalyst from catalytic reforming, catalyst and fines from
catalytic cracking, sludge from sulfur complex and H2S
removal facilities, spent caustic from liquid treating,
unleaded gasoline storage tank sediment, off-specification
product and fines from thermal processes, and sludge from HF
alkylation is adequately supported by these new analyses as
well as the original listing proposal. The new analyses
clearly support EPA's no list decision for the eleven
residuals listed above. In the case of additive risks, EPA
could find no circumstance which would suggest that
individuals would be simultaneously exposed to residuals
managed in an on-site landfill or land treatment unit. 
Similarly, for co-disposal, EPA's analysis emphasizes the
fact that these eleven residuals do not warrant listing,
even with great conservatism in the risk assessment. EPA's
Monte Carlo analysis strengthens these results and further
highlights the conservatism in EPA's risk assessment for
both the high-end analysis and the co-disposal scenario. In
fact, the Monte Carlo analysis illustrates that the risks
predicted by the high-end analysis clearly fall at levels
greater than the 95th percentile. (Phillips 00014)

Response: EPA is finalizing its decision to not list all but
one of the above wastes (EPA is listing crude oil tank
sediment). EPA appreciates the commenter's support for its
no-list decisions.


I.A.6. Other Groundwater Modeling Issues

I.A.6.a. Distance to Well

Comment 1: EPA Fails to Follow its Own Policy Decision by
Using the OSW Data Base to Determine the Distance Between
Landfills and Groundwater Wells.

In the development of EPA's technical approach for this
rulemaking, many discussions were held between EPA,
industry, and NPRA and API. During these early discussions,
industry proposed several alternatives to conducting the
RCRA 3007 Survey including the use of existing EPA data
such as the OSW data base. EPA strongly objected to the
approach of using existing data and stated that the RCRA
3007 Survey and site sampling were the only acceptable
approaches to obtaining data for this rulemaking. EPA
stated that existing data such as the OSW data base was not
acceptable because it was too general and was not specific
enough for the refining sector which is the focus of this
rulemaking.

EPA's decision to use the OSW data base is in direct
contradiction to its earlier determination to base its
rulemaking on the RCRA 3007 Survey and site sampling. EPA's
subsequent decision to use the OSW data base because the
3007 Survey did not have enough respondents is not
defensible. 

 EPA had limited resources to conduct the site sampling
 and implement the RCRA 3007 Survey. In discussions with
 industry, adjustments were made to both the survey and
 the site sampling to fit into EPA's budget. It was
 understood that EPA would use the RCRA 3007 Survey to get
 a representative sample of the information needed to
 conduct the analysis. It was never expected to obtain a
 100 percent response rate to questions such as distance
 to the nearest well.

 The 50 percent response rate to the RCRA 3007 Survey is a
 statistically sufficient sample. There is no reason to
 believe the missing 50 percent is statistically different
 than the 50 percent sample responses and a sample of 50
 percent is consistent with EPA goal of getting a
 representative refining industry sample from the survey. 

 The selection of the distance to the nearest drinking
 water well to be used in the ground water analysis will
 influence the results of the modeling and therefore the
 listing decision. Because the difference between the
 RCRA 3007 survey results and the OSW data base is
 significant (median distance to the nearest well of 2600
 meters vs 430 meters, respectively), EPA must use data
 that most accurately represents the refineries which
 would be affected by a listing. As EPA stated at the
 start of this rulemaking, OSW data base is not refinery
 specific and residuals being considered for listing. On
 the other hand, the 3007 survey is specific to refineries
 and to this rulemaking. (NPRA, 00004, pg 2)

Response: The RCRA Section 3007 questionnaire response for
well distances was incomplete. Of the 172 3007
Questionnaires returned, 27 facilities reported the presence
of nonhazardous on-site landfills used for the disposal of
any waste in the survey in any year. Of these 27, EPA found
that only 15 reported the distance to the nearest drinking
water well with any reliable documentation (e.g., well
location maps, groundwater flow gradients, company survey of
nearby wells). (only 10 out of 21 refineries with onsite
landfills reported well distances) and inadequate with few
supporting documents. Furthermore, wells may be placed
closer in the future. Therefore, EPA relied on well
distances obtained from the EPA Office of Solid Waste, OSW (Note: Office of Solid Waste, OSW, was renamed Office of Resource Conservation and Recovery, ORCR, on January 18, 2009)
Municipal Solid Waste (MSW) Survey. The survey is
statistically valid for the nationwide analyses. The Agency
believes that the information on distances to drinking water
wells in the Municipal survey can be used reasonably
reliably compared to the limited number of responses from
the refineries. The distribution of domestic drinking water
wells around petroleum refining facilities should be
reasonably similar. Furthermore, EPA notes that the
Questionnaire data only provides well location information
for evaluating on-site landfills, and even if used, would
have not impact the modeling results for off-site landfills. 
Because the risks from off-site landfills were higher or
comparable to risks calculated for on-site landfills, any
change in the results for on-site landfills is unlikely to
alter any listing decisions.

Comment 2: EPA Has Greatly Underestimated the Distance
Between Landfills and Groundwater Wells
 
The evidence further supports the fact that facility
boundaries and residential wells are not closely located. 
In fact, the results of the additive risk analysis provides
further support to the contention that EPA has greatly
overestimated the well distance location in the groundwater
analysis.

Using the well distances calculated from the RCRA 3007
survey data, API recalculated the 9-year peak groundwater
concentration at the receptor well. Based on these values,
and using the same high-end parameters, risks from benzene
in hydrorefining and hydrotreating catalysts decreased by a
factor of three for off-site disposal and a factor of five
for on-site disposal. Risks from on-site and off-site
disposal of arsenic in hydrorefining catalyst decreased by
an order of magnitude.

In the groundwater analysis for hydrotreating and
hydrorefining catalysts for the NODA, EPA used the OSW
Industrial Subtitle D Waste Management Facility Database to
determine the distance to the nearest well for both on-site
and off-site landfills. API strongly disagrees with EPA's
decision to use the OSW database in place of the data
available from the RCRA 3007 Survey. By EPA's own admission,
the well distance reported in the OSW database (median of
430 meters) is significantly smaller than the well distances
reported by landfills receiving petroleum residuals (median
of 2600 meters). Although EPA argues that only 50 percent
of the refineries with landfills responded to this survey
question, by using the OSW database, EPA has made the
assumption that the well distance for all of the non-
reporting refineries is less than the currently reported
median. EPA has no basis for making such an assumption; in
fact, it seems more likely that a facility did not report a
well distance because a well was not located close enough to
the facility to be a concern. In the absence of data to the
contrary, EPA should use the data available in the RCRA 3007
survey. In fact, in the Background Document for the
Groundwater Pathway Analysis, EPA stated that "[a]vailable
information [from the RCRA 3007 Survey] was restricted to
waste unit size (area and depth), geographical location of
the unit, and depth to groundwater and distance to the
nearest drinking water well, for on-site waste management
units". According to this statement, the results of the
RCRA 3007 survey were sufficient to evaluate groundwater
risks in the proposed rule.

EPA asserts that the OSW Survey yields data more appropriate
well distance data for its on-site landfill risk model than
the RCRA 3007 Survey because the RCRA 3007 Survey well
distance data had a 50 percent response rate, which EPA
believes is too low for yielding useable data. However, API
believes that the RCRA 3007 Survey is a more appropriate
database for onsite well distance because this database
reflects actual well distances for the on-site landfills at
refineries. The OSW Survey included all types of RCRA
landfills and thus is less directly applicable. At this
time, API has no information that suggests that non-respondent
facilities from either survey are different from
respondent facilities in any way that would affect
parameters estimated from their data.

Although the 50 percent response rate for the RCRA 3007
Survey well distance data is not ideal, response rate as an
isolated measure does not indicate whether parameters
derived from survey results are representative of the target
population. In any instance where response rates are less
than 100 percent, it is appropriate to question whether the
non-respondents differ in some meaningful way from the
respondents such that results derived for the respondents
are not representative of the survey's target population.
For this reason, non-respondent follow-up, whereby a
separate sampling effort is devoted to contacting and
collecting information from a sample of non-respondents, is
a part of some survey protocols. Because the RCRA 3007
Survey did not include non-respondent follow-up, there is
some unavoidable uncertainty about the applicability of the
data to its target population.

The well distance parameters estimated from the RCRA 3007
and OSW Survey data are different enough to indicate that
the OSW Survey does cover landfills with characteristics
different from those of the refineries. The OSW Survey
yields a high-end (10th percentile) well distance value of
120 meters and a median of 430 meters. The 10th percentile
and median well distance from the RCRA 3007 Survey are 625
meters and 2310 meters, respectively. In order for the
RCRA 3007 Survey and the OSW Survey to indicate the same
parameters for the risk model, only five percent of the non-
respondent facilities could have well distances that are
within the range established by the respondents. A full 75
percent of the non-respondents from the RCRA 3007 Survey
would have to have well distances between 120 meters and 305
meters, and 20 percent would need to be 120 meters or less. 
It is highly unlikely that the non-respondent facilities
from the RCRA 3007 Survey are this different, as a group,
from the facilities that responded. The facilities covered
by the OSW survey and the RCRA 3007 survey are of different
types and have different characteristics.

Thus, the OSW Survey clearly includes landfills that are
different from the on-site refinery landfills. Therefore,
the parameters derived from the RCRA 3007 Survey are more
appropriate for this rulemaking than those from the OSW
Survey. Concerns over response rate for the RCRA 3007
Survey are outweighed by the strong possibility that the
well distance data derived from the OSW Survey are not
applicable to the on-site refinery landfills.

Using the available well distance data from the RCRA 3007
survey, API modeled the distribution of well distances. API
performed statistical tests to determine the distributional
form of the data and determined that the data were log
normally distributed. A Monte Carlo simulation of the
distribution using the mean and standard deviation of the
available data and the @RISK software (Palisade Corp.; 5,000
iterations) revealed a median well distance of 2339 meters
and a high-end distance (10th percentile) of 847 meters. 
These values contrast significantly with the median and
high-end distances from the OSW database (430 meters and 120
meters, respectively). The results of this analysis clearly
indicate that the data from the OSW survey greatly
underestimate the distance from on-site refinery landfills
to the nearest receptor wells. Use of such unrealistic data
in the rulemaking would violate the requirement in 40 CFR 
261.11(a)(3)(vii) that EPA consider "plausible"
mismanagement scenarios.

Using the well distances calculated from the RCRA 3007
survey data, API recalculated the 9-year peak groundwater
concentration at the receptor well. Based on these values,
and using the same high-end parameters, risks from benzene
in hydrorefining and hydrotreating catalysts decreased by a
factor of three for off-site disposal and a factor of five
for on-site disposal. Risks from on-site and off-site
disposal of arsenic catalyst decreased by an order of
magnitude. (API, 00009, pg 14)

Response: See Response to Comment 1 above for the issue of
why the RCRA 3007 well distances are not appropriate. As
for the issue of what was reported in the 1995 Groundwater
Pathway Background Document "A review of the distance to
well values used in the groundwater model indicate that EPA
did, in fact, use the OSW database in the 1995 proposal,
although information in the background document suggests
otherwise", the document said well distances were available
in the survey responses it did not explicitly say well
distances from the RCRA 3007 were used in the data sources
section (Section 3.2) of the background document. EPA also
notes that the commenter's suggestion that the Questionnaire
well distance data be used for of-site landfills is not
logical. The Questionnaire provides information only about
well distances for on-site landfills and would not be
appropriate to use for off-site landfills under any
circumstances
 
Comment 3: RCRA 3007 database information should be utilized
to assess distances from onsite management units to down
gradient drinking water wells

Phillips call your attention to another aspect of the
modeling effort used to support EPA's proposed hazardous
waste listing for selected petroleum refining residuals. 
This is of particular importance to use because several of
our refineries have onsite waste management facilities long
distances form potential receptor wells. We believe this to
be a common situation as many refineries are sited on large
tracts of land, often purchased expressly to provide a
buffer between plant operations and human inhabitants. EPA
therefore should not discount the differences in distance to
down gradient wells between onsite and off-site waste
management units.

In the groundwater analysis for hydrotreating and
hydrorefining catalysts for the NODA, EPA used the OSW
Industrial Subtitle D Waste Management Facility Database to
determine the distance to the nearest well for both on-site
and off-site landfills. Phillips strongly disagrees with
EPA's decision to use the OSW database in place of the data
available from the RCRA 3007 Survey. By EPA's own admission,
the well distance reported in the OSW database (median of
430 meters) is significantly smaller than the well distances
reported by landfills receiving petroleum residuals (median
of 2600 meters). Although EPA argues that only 50 percent
of the refineries with landfills responded to this survey
question, by using the OSW database, EPA has made the
assumption that the well distance for all of the non-
reporting refineries is less than the currently reported
median. EPA has no basis for making such an assumption; in
fact, it seems more likely that a facility did not report a
well distance because a well was not located close enough to
the facility to be a concern or interpreted the 3007
questionnaire to limit responses to distances less than 500
feet. In the absence of data to the contrary, EPA should
use the data available in the RCRA 3007 survey. In fact, in
the Background Document for the Groundwater Pathway Analysis
(p. 11), EPA stated that "Available information [from the
RCRA 3007 Survey] was restricted to waste unit size (area
and depth), geographical location of the unit, and depth to
groundwater and distance to the nearest drinking water well,
for on-site waste management units." According to this
statement, the results of the RCRA 3007 survey were
sufficient to evaluate groundwater risks in the proposed
rule, however before publication of the proposed rule had
been rejected in favor of the OSW survey data. 

EPA believes that the OSW Survey yields data more
appropriate well distance data for its on-site landfill risk
model than the RCRA 3007 Survey because the RCRA 3007 Survey
well distance data had a 50 percent response rate, which EPA
believes is too low for yielding useable data. However, API
believes that the RCRA 3007 Survey is a more appropriate
database for onsite well distance because this database
reflects actual well distances for the on-site landfills at
refineries. 

We were surprised to learn form the March 1997 Supplemental
Background Document (Groundwater Pathway Risk Analysis
(pages 2-10)) that the nearest drinking water well distance
parameter was derived exclusively from the OSW Industrial
Subtitle D Waste Management Facilities Database for receptor
well distances from both onsite and offsite waste management
facilities. This distance was determined to be 430 meters
(median) and 102 meters (10th percentile). Data from the
RCRA 3007 database were not used to represent well distances
from onsite units ostensibly because the database was
incomplete. Documentation of this discrepancy includes: 

 Review of the preamble to the subject proposed rule (60
 FR 57747) and its supporting (August 1995) background
 documents, found mention of the use of the same receptor
 well distances (i.e., 102/ 430) but specifically
 indicated that they were derived from the RCRA 3007
 database (e.g., August 1995 background documents for
 ground waste pathway analysis (pg. 30)). In the preamble
 (60 FR 57759 col. 2) to the proposed rule EPA explicitly
 states, "For onsite landfills and LTU's the Agency used
 the data submitted by the industry in the Section 3007
 questionnaire to characterize the units in terms of the
 waste quantities disposed, surface area of disposal
 units, and distances to receptors. For offsite landfills
 and land treatment facilities from the Agency's
 "Industrial D Facility Study" (October 20, 1986)."

 The subject preamble additionally indicates that EPA
 completed an "exhaustive engineering review" of each 3007
 response and "believes that the data are reliable and
 represent the industry's current residual generation and
 management practices" (60 FR 57751 col. 3). This does
 not track with the well receptor distance for onsite
 facilities as this particular 3007 survey data was
 rejected by EPA without explanation until the issuance of
 the March 1997 Background Document referenced above. 
 Furthermore, there is no mention of this disparity, that
 we could fine. In the text of the NODA (62 FR 16747)
 although a short explanation is provided in a March 1997
 supporting background document.

Having participated in the review of the RCRA 3007 survey as
it was being prepared, we recall that the technical review
time for Section IX and X was severely limited as EPA was
anxious to distribute the survey. Section IX.C requests the
"closest unit boundary to the nearest down gradient (pubic)
private drinking water well (feet)." A similar question in
Section X.7, requests a map locating all public and private
drinking water wells with in 1 mile of the facility
boundary. This could explain why some refiners reported >1
mile rather than an exact distance. EPA could easily
solicit an actual distances from these refiners to improve
the database information. Any other 3007 responses could
similarly be addresses by a simple phone call, EPA did
significant follow up with individual refiners to verify
information contained in other portions of the 3007 survey,
why should potential data concerns for this parameter be
handled differently? EPA's decision to jettison all the
well distance data for onsite management units appears to be
extreme when follow-ups with refiners can be easily
accomplished. If EPA is uncomfortable with the response
rate it has ample time to contact the facilities that report
having onsite landfills to seek clarification or correction
of submitted data. These follow-ups would allow EPA to
substitute the data for onsite units into modeling runs well
in advance of a final decision for the hazardous waste
listing of petroleum refining residuals. EPA as previously
made inquiries of individual refiners to correct errors,
omissions, and misunderstandings in other areas of the 3007
questionnaire. Obtaining clarification on this specific
issue is not likely to tax EPA resources as the number of
responses that require reevaluation is likely small, perhaps
on the order of 25-30.

Using the available well distance data from the RCRA 3007
survey, [i.e., as reported in correspondence from Vierow
(SAIC) to Saleem (EPA)] API modeled the distribution of well
distances. API performed statistical tests to determine the
distributional form of the data and determined that the data
were log normally distributed. A Monte Carlo simulation of
the distribution using the mean and standard deviation of
the available data and the @RISK software (Palisade Corp.;
5,000 iterations) revealed a median well distance of 2339
meters and a high-end distance (10th percentile) of 847
meters. These values contrast significantly with the median
and high-end distances from the OSW database (430 meters and
120 meters, respectively). The results of this analysis
clearly indicate that the data from the OSW survey greatly
underestimate the distance from on-site refinery landfills
to the nearest receptor wells. (Phillips, 00014)

Response: The reference for well distances on page 30
(Table 4.4 ) of the August 1995 Background Document for the
Groundwater Pathway analysis was incorrectly listed as the
RCRA Section 3007 survey, the correct citation should have
been the OSW Survey of Municipal Landfills. See response to
Comment 1 in this section for a response to this issue. 


I.A.6.b. Active Life

Comment 1: EPA assumed a 20-year active life for off-site
landfills. See Supplemental Background Document; Listing
Support Analyses; Petroleum Refining Process Waste Listing
Determination; Active Lives of Landfills Used for Disposal
of Petroleum Refining Wastes. This factor is very important
because the waste volume inputs to the EPACMTP model are
derived by multiplying the annual waste volume by the unit
active life. Therefore, an inaccurate assumption of a short
active life for landfills will cause the groundwater model
to significantly underestimate risks.

The sole basis for EPA's assumption of a 20-year life for
landfills is a 1986 survey of municipal landfills. See
National Survey of Solid Waste (Municipal) Landfill
Facilities, EPA/530-SW88-034 (Sept. 1988). This report
states: "The average age of a facility is estimated to be
18.6 years." Id. at 8-1. In context, however, it is clear
that this statement refers to the age of the facility at the
time the survey was conducted, not the anticipated active
life of the landfill unit. EPA simply misconstrued this
report.

In an appendix to the survey report, the year that waste was
first placed in the surveyed landfill and the year all
active and planned units were expected to be completely
filled were reported. The average responses were 1967 as
the year the landfilled began operation and 2007 as the year
of expected closure. Thus, the average active life actually
reported in the survey was 40 years. Moreover, the survey
reported that 59% of national capacity remained at the
surveyed landfills to be utilized. This means that 41% of
the average landfill capacity was used over 18.6 years, so
that all landfill capacity would be utilized in
approximately 45.4 years. Clearly, an average life of 40-45
years is an accurate assumption -- not 20 years.

KGS conducted revised modeling runs using a 40-year life for
off-site landfills. Based on KGS's evaluation of this factor
and other parameters, the risks posed by potential
mismanagement of most petroleum refinery wastes covered by
the NODA require a hazardous waste listing, as discussed in
Section II below. (ETC, 00005, pg 4)

Response: EPA reexamined the report cited and concluded
that the assumed active life of 20 years may be an
underestimate. Using the data in the report, however, the
Agency calculated that an average active life of 30 years is
accurate, rather than the 40 year life suggested by the
commenter. EPA believes that the commenter simply summed
the reported average age of the landfills (19 years) and the
average remaining life (21 years) to obtain 40 years. This
calculation, however is not accurate, because it would
overestimate the active life for existing units. This is
because the average age in the report included closed units,
not only existing units, and thus does not reflect merely
the average life for units still in operation. Likewise,
the average remaining life in the report included planned
units, as well as existing units, and this also would tend
to increase the apparent active life for existing units. 
Correcting for this, EPA calculated a 30 year active life,
based on corrected values of 16.5 years for the average age
of active units, and 13.3 years for the average remaining
life (see Additional Listing Support Analysis, 1998 in the
docket to today's rule for full calculations). EPA has used
the revised active life (and correspondingly larger volumes)
to calculate the new risk numbers.

Comment 2: In the groundwater risk assessments performed in
support of the 1995 proposal, EPA assumed a 20 year active
life for both landfills and surface impoundments. The
assumption is extremely important, because the waste volume
inputs into the groundwater model are derived by multiplying
the annual volume (based upon 1992 data) and the length of
the unit active life. Therefore, an arbitrarily short unit
active life can substantially understate the very important
waste volume parameter used in the groundwater modeling. 

EDF challenged the 20 year active life assumptions in its
comments on the 1995 proposal, based upon the lack of
factual basis for the assumptions and the large number of
surface impoundments and landfills identified in refinery
RCRA Facility Assessments (RFAs) that had active lives
substantially beyond 20 years. In the NODA materials, EPA
attempts to provide additional justification for the 20 year
landfill assumption. As explained in this portion of the
comments, the information provided in the NODA actually
supports at least a 40 year active life assumption for
landfills.

With respect to offsite landfills, the sole basis for EPA's
20 year assumption is a survey of municipal waste landfills
conducted by an EPA contractor beginning in 1986 and
published in a 1988 report. The target population of the
survey was municipal landfills with at least one active unit
as of November 1, 1986. Closed and planned units were
included in the survey only where the facility had at least
the one active unit.

The age of the surveyed facilities is summarily discussed in
one sentence of the body of the report. The sentence reads
"The average age of a facility is estimated to be 18.6
years." Apparently, EPA has interpreted this sentence to
signify landfill age at closure, when in fact it is clear
from the rest of the document that the 18.6 years simply
pertains to age at the time the survey was conducted. 
Therefore, the 18.6 years bears no relationship to the
length of the entire active life of the landfill.

Elsewhere in the report, the contractor notes 59% of the
national capacity at the surveyed landfills still remains to
be utilized. Moreover, this percentage may be under
reported since it does not reflect new units to be built at
the surveyed facilities when the additional capacity is
required. On a per facility basis, the average remaining
capacity was also approximately 59%.

Thus, more relevant to the instant rulemaking than the 18.6
year value are the responses to questions reported regarding
the year waste was first placed in the landfill and the year
all active and planned units are expected to be completely
filled, as provided in the appendix. The average responses
to those questions were 1967 and 2007 respectively, meaning
the average active life actually reported in the survey was
40 years. 

Further, and of paramount importance, this 40 year period is
largely confirmed when considering the remaining capacity in
these facilities. If 41% of a facility's average landfill
capacity was used over 18.6 years, all of the landfill
capacity would be utilized in approximately 45.4 years,
assuming historic landfilling rates continue to apply. 
Again, as the contractor noted, even this 40-45 year average
active life is an understatement of the actual active life
of the surveyed landfills, since the reported values do not
fully reflect units to be built when additional capacity is
required.

In the case of onsite landfills, EPA calculated the active
life of refinery waste landfills using the 1992 data
provided as part of the industry surveys in the instant
rulemaking. The active life was calculated using three
different methodologies, and not surprisingly, EPA chose the
methodology that produced the shortest active life
irrespective of its relationship to reality.

Under Method 1 ultimately chosen by the Agency because it is
"simple", EPA generally assumed the active life equaled the
dates in the survey provided for facility start-up and
projected closure. Under Method 2, the projected closure
date was based upon the remaining capacity of the landfill,
assuming the rate of capacity usage in 1992 held true in the
future. Under Method 3, the projected closure date was
based upon the percentage of capacity used historically (not
just 1992). 

Method 1 produced a median value of 21.5 years, which EPA
uses as the basis for the onsite 20 year active life value
in the groundwater model. Before addressing the validity
of Method 1, several points should be noted from the outset. 
First, none of the EPA methods take into account additional
capacity to be built when needed, therefore all methods
reflect the same under reporting noted by the EPA contractor
for the offsite landfill survey. Second, the average value
calculated using Method 1 is 26.2 years. Since EPA uses
the average value for its offsite facility assumption (see
NODA Groundwater Risk Assessment at 2-4), the average value
should be used for onsite facilities as well.

More importantly, however, simplicity is an absurd
justification for relying upon Method 1 in the first place. 
It is the least accurate of the three options developed by
EPA, because it is the only option wholly unrelated to the
remaining landfill capacity. Unlike the offsite landfill
survey where the average survey responses and remaining
capacity roughly correlate, the onsite landfill survey
responses and remaining capacity analyses are not
consistent. In the face of such inconsistency, it is far
less accurate for EPA to rely solely upon unverified closure
projections, the basis for which is entirely unknown to the
Agency, when compared to the more objective inquiry based
upon remaining capacity.

The fallacy of Method 1 is perhaps best illustrated by its
application to landfill numbers 45 and 101 in EPA's data
base. Under Method 1, landfill 101 would have an active
life of 30 years. Yet since the landfill opened in 1983,
about 4% of the landfill capacity has been utilized,
including the 0.5% capacity used in 1992. If this
landfill closed in 2013 as predicted using Method 1, it
would close about 87% empty based upon usage in the 1983-
1992 time period. Similarly, landfill 45 would have an
active life of 39 years using Method 1, but since it opened
in 1991, much less than 1% of the landfill was utilized. 
Under Method 1, the landfill would close in 2020 almost
completely empty based upon usage in the 1991-1992 time
frame. Therefore, Method 1 results in the irrational
closing of landfills well before the vast majority of the
capacity is utilized. 

Methods 2 and 3 are both superior to Method 1 because they
rely upon a reasonable and objective basis for projecting
landfill closures instead of an unknown, unverified
subjective basis for such projections. Ironically, Method 2
is also the option most consistent with assumptions used by
the Agency in other parts of the rulemaking. The assumption
inherent in Method 2 that the data reported for 1992 is an
accurate indicator of future management practices is
precisely the assumption used by EPA in other parts of its
risk assessments, including the waste volume parameter. For
example, EPA assumes the volumes of waste generally annually
are the same amounts generated in 1992, and as noted above,
it is this annual volume rate that is multiplied by the
active life to derive the volume input into the groundwater
model. It is arbitrary and capricious for EPA to base much
of its modeling upon 1992 data, including one of two values
used to derive volume projections, only to reject a
methodology based upon the identical assumption because
another option producing a less protective result is
"simpler".

Significantly, the average active life of an onsite landfill
using Method 2 is 39.2 years. Accordingly, use of Method
2 more closely tracks the results of the offsite municipal
landfill survey discussed above. It would be illogical to
expect onsite landfills to have a shorter active life than
municipal waste landfills due to the economic advantages of
operating onsite landfills for facilities such as refineries
generating substantial quantities of wastes, and the greater
regulatory attention devoted to municipal waste landfills
subject to federal technical requirements and mandatory
state permitting.

In fact, given the likelihood that refineries will be
landfilling wastes onsite for the indefinite future, and
building capacity as needed to engage in that practice, the
Method 3 average active life of 56.6 years may be the most
accurate number of the three methods. Accordingly, while
the Method 2 average active life would essentially double
EPA's assumed active life, it is certainly "plausible" that
an onsite refinery waste landfill would be operating for a
much longer period of time. See 40 CFR 261.11(a)(3)(vi). 
Since the high-end volumes in the groundwater modeling do
not reflect longer active lives than the average values
(i.e., only the annual generation rate is adjusted, not the
multiplier reflecting the landfill active life), EPA's
current modeling methodology does not account for longer
than average active lives, irrespective of the ultimate
value chosen. 
In isolation, the volume parameter understatement is most
important in the case of unleaded gasoline storage tank
sludge. Adjusting only the volume parameter for the onsite
landfilling scenario to reflect 39.2 years of median annual
waste volume, KGS determined the resulting groundwater
pathway risk doubled when compared to EPA's results. 
Perhaps more importantly, when the volume parameter is
modified in conjunction with other necessary changes as
discussed below in Section II.I [of EDF's comment], the risk
results are more widely and profoundly increased.

To summarize, there is no factual basis for the assumed 20
year active landfill life in EPA's groundwater modeling. 
The report and data relied upon by EPA for the assumption
actually demonstrate an active life at least twice that
length is required. Moreover, by not adjusting the high-end
volume parameters to reflect longer than average active
lives, EPA high-end volume parameters do not reflect actual
high-end conditions. (EDF, 00006, pg 26)

Response: See response to Comment 1 above for off-site
landfill life. In the NODA, EPA provided an analysis of the
data for on-site landfills for refineries from the 3007
Questionnaire, showing a calculated median of about 21 years
for on-site landfills. The commenter disputed the 20 year
calculation, and cited an alternative method presented by
EPA in the NODA to calculate a 39 year average (i.e., mean)
active life, which the commenter argued EPA should use. 

 In the NODA analysis, the Agency used the projected date
for closure of on-site landfills reported by refineries in
the Questionnaire to estimate active lives. EPA also
examined alternative methods to calculate on-site landfill
life for use when facilities did not report the projected
date of closure. These alternative methods required EPA to
use the remaining capacity reported for the units, assume
disposal rates for all wastes in the landfills would remain
constant, and thereby estimate when the landfill may reach
full capacity. EPA believes the direct method chosen is
most appropriate because it uses the actual landfill lives
reported in the questionnaire, rather than relying on
estimating remaining active life by projecting past waste
disposal rates into the future. This alternative approach
is especially uncertain when the landfill are relatively
new, thereby requiring the extrapolation of a small
percentage of used landfill capacity into the far future,
which means that small variations or errors in the used
capacity of a landfill may lead to widely varying landfill
life projections. Thus, EPA did not revise its modeling for
on-site landfills to reflect a longer landfill life. EPA
also used the median active life, rather than the average
suggested by the commenter, because the median value lessens
the impact of widely variable data and outliers. EPA notes
that the only data available for off-site municipal
landfills were average values, not medians, so the Agency
had no choice but to use the average estimate active life
for the off-site landfills. 

Comment 3: EPA has appropriately determined the active lives
of landfills. In Section 6.0 of the Listing Support
Analyses, EPA describes three methods for calculating the
active life of a landfill. EPA has appropriately selected
Method 1 as the optimal approach. In both Method 2 and 3,
assumptions regarding prediction of future disposal patterns
and landfill closure only after the landfill reaches
capacity are likely to overestimate the life of the
landfill, as supported by EPA's calculations. (API, 00009,
pg 24)

Response: The Agency appreciates the commenter's supportive
comment; EPA tends to agree with this comment and believes
that Method 1 provides the best estimate of active life for
on-site landfills. EPA further notes that Methods 2 and 3
are extremely sensitive to the reported volumes disposed in
1992, and/or the capacity of the landfill used to date. If
the capacity remaining is large, or the volume of waste
disposed in 1992 very small, this will lead to potentially
large overestimates in active life.

I.A.6.c. Landfill Size

Comment 1: In previous listing determinations, EPA has
always used a standard size for both off-site and on-site
landfills. In this rulemaking, however, EPA decided to vary
the size of on-site landfills depending upon the waste
streams evaluated. The landfill sizes varied from 24,594
square meters for CSO sludge to 145,692 square meters for
off-spec thermal products and fines for the median value,
and from 28,329 square meters for HF alkylation sludge to
202,350 square meters for FCC fines and catalysts for the
high-end value. Of course, landfill size is an important
variable in the EPACMTP model, and manipulation of this
variable can significantly affect the risk results.

EPA has provided no explanation for its decision to vary on-
site landfill sizes to such a significant degree for
different petroleum wastes when projecting plausible
mismanagement scenarios. Since any petroleum waste can be
disposed in any on-site landfill, plausible mismanagement
should assume that any waste will be disposed in units
representing the largest median and high-end values. It
simply makes no sense for EPA to evaluate the risks posed by
disposal of HF alkylation sludge in a landfill that is
arbitrarily just 1/5 the size of the landfill used to
evaluate disposal of off-spec thermal products and fines. 
It also makes no sense to assume a standard size for off-
site landfills, but to dramatically vary the size of on-site
landfills for various petroleum wastes.

For this reason, KGS conducted its modeling using the CSO
waste median and high-end landfill area and depth for all
on-site landfill disposal scenarios. Based on KGS's
evaluation of this factor and other parameters, the risks
posed by potential mismanagement of most petroleum refinery
wastes covered by the NODA require a hazardous waste
listing, as discussed in Section II below. (ETC, 00005, pg
6)

Response: The selection of landfill sizes in the on-site
landfill modeling was strictly based on data reported in the
RCRA 3007 survey. Onsite landfill sizes were wastestream-
specific because the disposal data were wastestream-
specific. An explanation was provided in the groundwater
pathway background document, that areas were used as
reported in the survey. The area distributions were not
manipulated in any way. Wastestream-specific landfill size
data were not available for offsite landfill sizes,
therefore, standard sizes were used in the case of offsite
landfills. EPA believes its approach of calculating
different unit areas for different wastes was reasonable
because they are reflective of actual operating practices,
and another approach may result in unrealistic or
unreasonable assumptions regarding waste management
practices.

Furthermore, for a fixed waste volume, larger landfill areas
may not necessarily produce greater groundwater risk. In
addition, for fixed values of waste quantity, landfill area
within a certain range is not necessarily a significantly
sensitive parameter and, in fact, very large landfill areas
can actually produce lower receptor well concentrations. 
See the Additional Groundwater Pathway Risk Analyses,
Supplemental Background Document (1998). See also response
to NPRM comment 1 of Section III.J. To support this, EPA
notes that unit area was a high end parameter for only one
of the scenarios (hydrorefining catalyst). Conversely,
waste volume is a high end parameter for most of the
scenarios.

Table I.A.1, below, summarizes unit area data from various
sources in the docket. Specifically, the landfill areas
used for each waste are presented in conjunction with the
"universe" of landfills (as suggested by the commenter). In
comparing waste-specific unit areas to the statistics
generated when considering all landfills (in the first row),
median areas for most wastes are higher while high end areas
for most wastes are lower.


Table I.A.1. Landfill Sizes Used for Onsite Landfilling of
Petroleum Refining
Wastes a


Waste Type
Number of
Landfills
Area, 50th
%ile, sq.
meters
(acres)
Area, 90th
%ile, sq.
meters
(acres)
High End Parameters e


Contingent
Management for
CSO sediment b
33 b
25,000
(6.166)
202,000 (50)
Waste volume,
well centerline


Co-disposal
analysis c
8 c
---
202,000 (50)
---


CSO sediment
2
62,000
(15.2)
121,000 (30)
Waste volume, 
receptor distance


FCC catalyst and
fines d
16
29,000
(7.13)
202,000 (50)
---


Hydrotreating
catalyst
5
30,000
(7.38)
121,000 (30)
Waste volume, receptor
distance (for benzene);
infiltration rate,
receptor distance (for
TC cap benzene); waste
volume, TCLP
concentration (for
arsenic)


Hydrorefining
catalyst
4
31,000 (7.7)
121,000 (30)
Waste volume, unit area
(for benzene); 
infiltration rate,
receptor distance (for
TC cap benzene); waste
volume, receptor
distance (for arsenic)


Unleaded
gasoline tank
sludge d
6
30,000 (7.5)
146,000 (36)
---


Off-spec product
and fines from
thermal
processing
3
146,000 (36)
202,000 (50)
Waste volume, 
receptor distance


HF alkylation
sludge
1
28,000 (7)
28,000 (7)
Infiltration rate, 
receptor distance


a. Unless otherwise indicated, all surface area data are
from Appendix C of "Supplemental Background Document for
Groundwater Pathway Risk Analysis," 1997. The number of
landfills used as the bases for these statistics is from
"Listing Background Document for the 1992-1996 Petroleum
Refining Listing Determination," 1995 (e.g., page 92). The
above table shows, for example, that four onsite landfills
were used for the disposal of hydrorefining catalyst in any
year reported (not necessarily in 1992). The median value
and 90th percentile unit areas for this subset of refinery
landfills is as indicated (because of the small number of
data points in this case, the 90th percentile value
corresponds to the maximum value). This information
describing how area statistics were determined is presented
as footnotes on page 92 of "Listing Background Document,"
and in similar tables throughout that report.
b. Thirty three landfills accepted any of nine petroleum
refining wastes in any year and were used for the active
life calculations described in the NODA. (These nine
wastes, representing those listing wastes for which onsite
landfill modeling was conducted, are CSO sediment, FCC
catalyst and fines, hydrotreating catalyst, hydrorefining
catalyst, Claus and SCOT catalyst, unleaded gasoline tank
sludge, off-spec product and fines from thermal processing,
HF alkylation sludge, and sulfur sludge. Onsite modeling
for crude oil tank sludge was not conducted.) Surface area
data from these 33 landfills were used for developing the
unit area assumptions of the contingent management scenario.
c. From Appendix D of Supplemental Groundwater Pathway Risk
Analysis. Unit area determined by distributing 90th
percentile unit areas for 8 wastes and taking the 90th
percentile value of this array.
d. Data for unleaded gasoline tank sediment and FCC
catalyst and fines are taken from "Listing Background
Document," 1995, pages 39 and 68, respectively.
e. From Table C.1 of Supplemental Groundwater Pathway Risk
Analysis. Sensitivity analyses were conducted for each
waste, scenario (i.e., onsite or offsite) and constituent. 
For each model run, two of the following parameters were set
to high end: unit area, waste volume, TCLP concentration,
infiltration rate, receptor well distance, distance from
centerline, and receptor well depth. For each waste, a
different combination of high end parameters results in the
highest receptor well concentration.

Comment 2: Landfill area size continues to be one of the
most important modeling parameters in EPA's groundwater risk
assessment. In fact, landfill area is one of two default
high-end parameters used by EPA where it failed to conduct a
sensitivity analysis in the NODA Groundwater Risk Assessment
(i.e., co-disposal, unleaded gasoline storage tank sludge). 

In previous listing determinations, EPA employed a standard
onsite and offsite landfill for the purpose of setting
landfill area, depth, and other relevant modeling inputs. 
Unfortunately, once again EPA has diverted from past
practice and used modeling inputs that cannot be sustained.

Onsite landfill areas vary substantially depending upon the
waste stream. The areas range from 24,594 square meters
(contingent CSO sludge) to 145,692 square meters (off-spec
thermal products and fines) for the median area value, and
from 28,329 (HF alkylation sludge) to 202,350 square meters
for the high-end value (FCC fines and catalysts). 

EPA offers no explanation in the 1995 proposal or the NODA
as to why the onsite landfill sizes should vary so much when
projecting plausible mismanagement scenarios, other than the
varying sizes simply reflect those landfills that happened
to be used for particular wastes in 1992. In fact, since
there is no technical or legal bar for any onsite
nonhazardous refinery landfill to receive any nonhazardous
refinery waste, the groundwater modeling is not indicative
of the plausible types of mismanagement the Agency is
required to consider pursuant to 40 CFR 261.11(a)(3)(vii). 
Indeed, since EPA is required by law to assess present and
potential hazard, EPA's failure to assess the potential
risks posed by the disposal of HF alkylation sludge in a
landfill larger than 1/5 the area of the median off-spec
thermal products and fines onsite landfill is arbitrary and
capricious.

EPA implicitly acknowledges the lack of validity in its
onsite landfill area projections by using standard offsite
landfills for all wastes, and a standard onsite landfill
when evaluating the co-disposal scenario. In the offsite
case, EPA uses the standard landfill for all wastes
notwithstanding the fact that individual wastes were
disposed at different landfills in 1992. Thus, EPA
employed a wholly different approach for offsite landfills
v. onsite landfills, despite the similarity in circumstances
presented. In both instances, landfills may receive
individual refinery wastes in one year but not the next. 

As discussed above, EPA modeled the onsite landfill co-
disposal scenario using a high-end area value, and as Table
D.2. of the NODA Groundwater Risk Assessment reveals, chose
one landfill area size to represent the co-disposal
scenario. Therefore, in assessing the co-disposal
scenario, EPA projected the landfilling of HF alkylation
sludge and other wastes in larger landfills than it
projected when evaluating the wastes individually. Since
the same onsite landfills are the subject of both analyses,
the co-disposal modeling recognizes that refinery wastes may
be managed in any onsite landfill in a given year. It is
arbitrary and capricious for EPA to project potential
mismanagement of refinery wastes in the larger onsite
landfills under one scenario but not the other.

KGS conducted its individual waste composite modeling using
the CSO median and high-end landfill area and depth
characteristics for all onsite scenarios. In this manner,
the KGS composite modeling is more reflective of refinery
waste plausible mismanagement. The composite modeling
results are discussed below in Section II.I of the comments.

Finally, while the Agency employed a standard offsite
landfill area for all wastes, the areas values selected were
arbitrarily small (2,020 square meters median; 162,000
square meters high-end). EPA purportedly derived these area
sizes from an industrial landfill survey database, but to
the best of our knowledge, neither the survey report or the
methodology used to gather the data has been provided and
subject to notice and comment in this rulemaking. Instead,
the NODA Groundwater Risk Assessment simply references other
documents, which in turn, simply reference the database
without providing comprehensive information on survey
methodology. Therefore, we are unable to comment on the
validity of the database except to note it appears to be the
same database prepared for the HWIR rulemaking where the
Agency candidly admitted the survey "was not designed to
collect accurate estimates" on landfill area. See 60 FR
66358 (December 21, 1995).

Furthermore, insofar as EPA is relying upon the same survey
referred to in HWIR, this survey was taken of onsite
industrial waste landfills, and therefore does not even
apply to the relevant universe of facilities. Moreover,
since municipal solid waste landfills can receive the
refinery wastes at issue in this rulemaking, and EPA
relies upon municipal landfill data for other offsite
facility attributes (i.e., length of active life), it is
arbitrary and capricious for EPA to rely upon irrelevant
onsite landfill data when offsite landfill data is available
(see discussion immediately below) from the same source EPA
uses for other assumptions in its modeling. 

The average area reported for active municipal waste
landfills in EPA's 1986 survey was 131,527.50 square meters
(32.5 acres), an area many times greater than EPA's median
value in the instant rulemaking, and almost equal to the
high-end value. See EPA Offsite Landfill Survey at A-12. 
Moreover, more than half of the municipal waste landfills
surveyed in 1986 were between 10-100 acres, or at least
40,470 square meters (over 20 times larger than EPA's median
value). Over six percent of the municipal waste landfills
were larger than 100 acres, or greater than 404,700 square
meters.

As EDF noted in its comments on the 1995 proposal, the high-
end value in the instant rulemaking is about 1/6 the area of
the high-end 949,317 square meter Subtitle D landfill
modeled in the carbamates risk assessment. The central
tendency value in the carbamates risk assessment was 451,262
square meters, approximately 223 times larger than the
median offsite landfill are value used in the NODA.

In summary, onsite landfill area sizes inappropriately vary
by waste stream based on data for 1992 only that is not
determinative of practices in any other given year,
consequently for some wastes the modeled areas are
arbitrarily small. For offsite landfills, EPA correctly
employed standard landfill area values, but the values
selected are also arbitrarily small because they lack any
relevant factual basis, and are inconsistent with previous
rulemakings. (EDF, 00006, pg 41)

Response: EPA addressed the reasons for using different
onsite landfill areas for different wastes in comment 1
(immediately above). EPA also wishes to correct the
commenter's statement that EPA only considered landfills
used during 1992. In fact, EPA considered all landfills
used in any year for the disposal of each waste, therefore
significantly increasing the number of landfills used in the
assessment. Comment 1 above also addresses the commenter's
concerns regarding the different approach used for onsite
versus offsite landfills. 

In response to the commenter's concern regarding the unit
area used for the co-disposal analysis, EPA notes that a
deterministic analysis forces the use of a single landfill
area. EPA believes its approach was appropriate because it
could no longer use waste-specific landfill areas in
assessing the disposal of multiple wastes in a single
landfill. Because so many different waste combinations were
being disposed, the complexity of assessing the plausibility
of each waste combination with each landfill would make any
co-disposal analysis difficult or impossible. EPA also
notes that it considered all landfills in its co-disposal
Monte Carlo analysis, as described in NODA Supplemental
Background Document for Groundwater Risk Assessment. 

In response to the commenter's concern regarding the small
median value for offsite landfills, EPA acknowledges that
the cited area is in error. The median and high-end waste
unit areas used in the two high-end parameter analysis were
derived from the industrial subtitle D landfill survey
database as stated in the background document; however, the
median landfill area was incorrectly interpreted to be 2,020
square meters, when in fact it should have been 20,200
square meters. The high-end landfill area of 162,000 was
correctly represented in the analysis. The Agency has
conducted revised two high-end parameter modeling analyses
with a median landfill area of 20,200 meters. The Agency
has also expanded the analysis to also include municipal
landfill area distributions. The revised and expanded
analyses are presented in the new 1998 background document,
Additional Groundwater Pathway Analysis.

EPA agrees that the median area used by EPA in this analysis
was in error, and believes that the data for off-site
municipal landfill area appear more relevant to the modeling
of off-site landfills than the industrial data base used by
the Agency. Therefore, EPA revised the groundwater modeling
for off-site landfills to reflect the larger areas
associated with municipal landfills, and the risk results
incorporate the revised landfill areas. EPA notes that the
use of municipal landfill data is entirely appropriate
because the 3007 Questionnaire results showed that at least
one-third of all landfills used for refinery wastes are
municipal waste landfills ("Offsite Subtitle D Landfills
Used for Disposal of Petroleum Refining Wastes," in
"Additional Listing Support Analyses," 1998).

I.A.6.d. Biodegradation

Comment 1: EPA Should Incorporate Biodegradation Rates Into
the EPA Composite Model with Transformation Products
(EPACMTP) Groundwater Model

The EPACMTP model, used to predict the fate and transport of
constituents in the saturated zone, is designed to include
first-order biodegradation rate constants in its derivation
of dilution and attenuation factors (DAFs). For purposes of
this listing determination, however, EPA has chosen to set
biodegradation rates for all constituents equal to zero (no
biodegradation) even though biodegradation of many of the
constituents of concern is known to occur.

Although API is pleased that OSW has reviewed the Krumholz
et al. (1996) paper, we are concerned that its
interpretation of that summary of anaerobic BTEX
biodegradation tends to focus only on those statements which
lend support the Agency position on not including a
biodegradation rate constant for benzene in this modeling. 
For example, Krumholz et al. observe that while there are
numerous studies that do not show evidence of anaerobic
biodegradation of benzene, they also observe that those
results may be biased because they 1) have not been carried
out for a very long period of time (e.g., only a matter of a
few months), and 2) that most have been performed on
mixtures of BTEX, and that there is evidence that the TEX
compounds may be preferentially biodegraded (i.e., benzene
biodegradation might only occur once the TEX was depleted). 
They also conclude that " the biodegradation of BTEX
hydrocarbons has been clearly demonstrated to occur under a
variety of anaerobic conditions." (Section 3.7, p. 91). 
Further, regarding the field studies summarized in the
Krumholz article, it is important to note that 3 of the 10
field sites (not 2 of 15 as noted in the NODA) have
documented field anaerobic biodegradation of benzene. Also,
and importantly, a closer review of the individual papers
for those sites (and other papers describing research at
those sites) shows that at least 8 of those sites have shown
aerobic biodegradation of benzene. 

We agree with the Agency that the geochemical and biological
processes responsible for mineralization of benzene under
these conditions are indeed complex. It is a difficult task
to isolate and characterize the response of indigenous
microorganisms to the presence of benzene under either
anaerobic or aerobic conditions. However, from a practical
perspective, it may be most valuable to consider the results
of two recent synoptic studies of the characteristics and
behavior of hundreds of BTEX plumes from gasoline release
sites (Rice et al., 1995; Mace et al., 1997). Collectively
these studies include data from over 800 field sites, and
they confirm the contribution of biodegradation processes
(either anaerobic or aerobic or both) in limiting the mass
transport of dissolved benzene in virtually all cases. In
California, 90% of the benzene plumes studied decreased to
less than 5 ppb at a distance of less than 260 feet from the
source. In Texas, 90% of the benzene plumes decreased to
less than 10 ppb in under 380 feet. 

In conjunction with the Hazardous Waste Identification Rule
(HWIR) for Process Wastes, API is currently working closely
with the Agency to evaluate potential biodegradation rates
which can be input in the EPACMTP. EPA will assemble a Peer
Review Panel of outside biodegradation experts (scheduled to
meet August 25-26, 1997) to evaluate criteria for including
appropriate biodegradation rate constants for selected
organic constituents. EPA is also assembling a team of in-
house technical experts which will make a final
determination on inclusion of any biodegradation factors in
the EPACMTP model used for HWIR. 

API, in conjunction with other members of the regulated
community, will submit data shortly regarding anaerobic
biodegradation rate constants of numerous constituents for
consideration in the HWIR rulemaking. Given the recent
delays in promulgation of the petroleum residual listings
rule (currently scheduled for May 29, 1998), EPA should have
ample time to reach a conclusion on incorporation of
anaerobic and aerobic biodegradation rates in the HWIR
context, and then incorporate those rates in the risk
analyses for this rulemaking in accordance with the listing
criterion in 30 CFR 261.11(a)(3)(v). API will continue to
provide further documentation of this phenomenon to EPA
during its development of this and related rules affecting
the petroleum industry. (API, 0009, pg 11)

Response: EPA conducted an evaluation of all submitted data 
and the documented anaerobic biodegradation studies of
benzene suggest that in-situ anaerobic biodegradation of
benzene rates may be strongly dependent on site-specific
conditions (e.g. availability of electron acceptors,
availability of nutrients, temperature, etc.). Furthermore,
the necessary conditions for anaerobic benzene
biodegradation are poorly understood. The absence of
biodegradation can be caused by the presence of competing
substrates, such as, toluene, xylenes, and ethylbenzene, as
well as inadequate geochemical conditions and lack of proper
electron acceptors (nitrate, sulfate, iron, etc.). 
Therefore, because of the lack of information to correlate
site-specific controlling factors to biodegradation, the
limited number of field data, and the field and laboratory
evidence that benzene tends to be recalcitrant to anaerobic
biodegradation, biodegradation of benzene was not considered
in the 1995 analysis or in the current groundwater pathway
analysis. Also, as EPA noted in the proposed rule,
preliminary modeling suggests that incorporation of possible
biodegradation rates into the analysis would result in
relatively minor decreases in risk (i.e., reductions of 2 to
44%, depending on the waste; see proposed rule at 60 FR
57761).

The Agency is currently examining the protocol for the
measurement of anaerobic biodegradation rates for chemicals
in subsurface environments, and has organized a workshop as
a forum for distinguished researchers in the area of
anaerobic biodegradation to discuss and debate various
issues related to anaerobic biodegradation, with a view to
evaluate and improve the protocol, and to develop criteria
for the evaluation of anaerobic biodegradation rate data for
organic chemicals in the subsurface environment.

Furthermore, biodegradation of benzene was included in the
1995 groundwater pathway analysis, using lag times of 1, 5, 
and 10 years and considering biodegradation rates of 1.E-5
and 1E-4 day-1 . Results of that analysis indicated that
receptor well concentrations might be reduced to between 98%
to 57% of their value with no biodegradation. A reduction
to 57% is not sufficient to reduce Crude Oil Tank Sediment,
Hydrotreating Catalyst, or Hydrorefining Catalyst benzene
risk in the current analysis to below 1E-5. 

Comment 2: EPA Should Incorporate Biodegradation Rates Into
the EPACMTP Groundwater Model

The EPACMTP model, used to predict the fate and transport of
constituents in the saturated zone, is designed to include
first-order biodegradation rate constants in its derivation
of dilution 
and attenuation factors (DAFs). For purposes of this
listing determination, however, EPA has chosen to set
biodegradation rates for all constituents equal to zero (no
biodegradation).

This issue is not unique to this rulemaking. In conjunction
with the Hazardous Waste Identification Rule (HWIR) for
Process Wastes, API is currently working closely with the
Agency to evaluate potential biodegradation rates which can
be input in the EPACMTP. EPA will assemble a Peer Review
Panel of outside biodegradation experts (scheduled to meet
August 25-26, 1997) to evaluate criteria for including
appropriate biodegradation rate constants for selected
organic constituents. EPA is also assembling a team of in-
house technical experts which will make a final
determination on inclusion of any biodegradation factors in
the EPACMTP model used for HWIR. EPA should have ample
time to reach a conclusion on incorporation of anaerobic and
aerobic biodegradation rates in the HWIR context, and then
incorporate those rates in the risk analyses for this
rulemaking. This is especially true since any rates
incorporated into the EPACMTP for HWIR purposes will have
been thoroughly studied, and be very conservative, with
little or no additional staff time needed for technical
reevaluation of the selected biodegradation rates in the
risk analysis for this rule. (Phillips, 00014)

Response: See Response to Comment 1 above.

I.A.6.e. Plume Centerline

Comment 1: In the supplemental groundwater pathway risk
analysis, EPA has continued to vary the location of receptor
wells across the width of the contaminant plume in both the
deterministic and Monte Carlo modeling runs, rather than
fixing the receptor well on the plume centerline as is
consistent with Agency policy and precedent. See 59 FR 9830
(March 1, 1994), 59 Fed. Reg. 66,086 (Dec. 22, 1994). By
varying the location of the receptor well, the risk analysis
assumes that wells will often receive significantly lower
concentrations of contaminants at a given distance from the
source area, and this results in underestimating the risks
posed by land disposal mismanagement.

As discussed more fully in the KGS report, the EPACMTP model
assumes that the groundwater contaminant plume has a bell-
shaped concentration distribution, with the highest
concentration occurring along the plume centerline. This
distribution assumes that the waste is uniformly distributed
and the geology is homogeneous which, of course, is not a
realistic reflection of real-world waste disposal and
geologic conditions. As EPA knows, many geological settings
are heterogeneous and contain preferential pathways for
contaminant migration such as sand channels or fractured
zones. EPA's efforts to compensate for this model
limitation actually contribute to a greater underestimate of
risks. KGS Report at 3. Even locating the receptor well on
the plume centerline, thereby capturing the highest
concentrations produced by the model, does not necessarily
reflect the highest concentrations the modeled leachate
could generate if released in a heterogeneous geologic
setting.

For these reasons, EPA has previously located the receptor
well on the plume centerline as a reasonably conservative
assumption when evaluating groundwater risks for listing
determinations. KGS evaluated the sensitivity of this
parameter and conducted its analysis fixing the receptor
well on the plume centerline. Based on KGS's evaluation of
this factor and other parameters, the risks posed by
potential mismanagement of most petroleum refinery wastes
covered by the NODA require a hazardous waste listing, as
discussed in Section II below. (ETC, 00005, pg 4)

Response: There are two main technical issues in the above
comment: locating receptor well along the plume centerline;
and effects due to local heterogeneity in conjunction with
the placement of receptor well.

The first concern is addressed below in response to comment
2. In essence, the main objective of the probabilistic
placement of receptor well is to mimic the real-world
distribution of well locations as realistically as possible.

The issue of heterogeneity is addressed below.

The Agency currently uses homogeneous flow and transport
models to simulate contaminant migration in the vadose and
saturated zones. In these models, average or effective'
properties are utilized. By using the effective properties,
the plume geometry is symmetric about the centerline with
the maximum concentration occurring along the centerline. 
However, it also represents the expected plume geometry or
the geometry with the maximum probability of occurrence. 
With local heterogeneity, the plume geometry may no longer
be symmetric and the maximum concentrations do not
necessarily occur along the plume centerline.

However, with the receptor well being probabilistically
located, the probabilistic distribution of relative distance
between the plume centroid (where the maximum concentration
occurs) and the well location remains relatively unchanged. 
From the Monte-Carlo simulation standpoint, with adequate
number of Monte-Carlo realizations, the distribution of
contaminant concentrations at receptor well should not be
affected by local heterogeneity.

Some of the heterogeneity effects have been incorporated
into the model, e.g, macro-hydrodynamic dispersion due to
hydraulic conductivity contrast. For the macro-dispersion
phenomenon which reflects the dependency of hydrodynamic
dispersion on spatial scales, the Gelhar's scale-dependent
relationship for the hydrodynamic dispersivity is employed
in the model.

It must be pointed out here also that local heterogeneity
could affect the distribution of contaminant concentration
in both positive (concentration increases) and negative
(concentration decreases) ways. For instance, the presence
of hydraulically conductive fractures could cause
contaminant to travel faster due to an increase in
groundwater velocity, along certain preferential pathways. 
However, there are several types of fractures, and not all
fractures are hydraulically conductive. Old faults tend to
be clay-filled, and some old fractures with history of
hydrothermal processes could have been plugged by
mineralization. These faults and fractures tend to function
as flow barriers. Furthermore, retardation due to matrix
diffusion into background rock matrix is also possible. 
Transport through fractured rocks could be retarded by
contaminant absorption via matrix diffusion. Because of the
narrowness of most preferential pathways, the probability of
these pathways being intercepted by receptor wells also
diminishes.

Because the local heterogeneity could affect the
distribution of contaminant concentration in both the
positive and negative manners, with an adequate size of
sample population, the two opposite effects are likely to
negate each other so that the final concentration
distributions based on Monte-Carlo analyses are not
significantly influenced by the presence of local
heterogeneity. 

In addition, a certain amount of conservativeness has been
incorporated into the analyses. For example: the assumption
that the saturated thickness remains constant (which causes
the groundwater to be faster, the peak concentration to
arrive at the receptor well more quickly, and contaminant
concentration to be greater due to less dilution; and the
exclusion of biodegradation. In the case of high-end
parameter analyses, the contaminant concentrations are in
most cases between the 95th and 99th percentiles of the
corresponding distributions based on Monte-Carlo analyses.

Comment 2: Notwithstanding both precedent and expressed
Agency policy to locate the receptor well in the plume
centerline in listing determination risk assessments, EPA
continues to vary the location of the receptor well in the
NODA deterministic and Monte Carlo modeling runs. Like the
1995 proposal, no explanation or justification is provided
regarding this violation of Agency policy, and the approach
is inconsistent with RCRA's underlying goals of preventing
pollution in the first instance, and protecting human health
and the environment. Whether or not a receptor well happens
to be located in the plume centerline at a particular point
in time is irrelevant to the presence of the plume itself
and thus the protection of the resource for present and
future uses. By juggling well locations, EPA is forsaking
its mission of groundwater protection by playing geographic
roulette with the health of the resource and its potential
users.

In addition to the legal and policy bases for locating the
receptor well in the plume centerline, there are also
technical reasons as well. As noted in the KGS report, the
large Dispersivity values used in EPA's groundwater model do
not reflect reality. Further, as the model user's guide
notes, the scientific literature does not provide a strong
basis for choosing Dispersivity values when modeling generic
scenarios. Therefore, locating the receptor well in the
plume centerline reduces the overall level of technical
uncertainty in the model predictions. (EDF, 00006, pg 40)

Response: The Agency disagrees with the commenter on this
issue. While EPA may have placed the receptor well on the
plume centerline in modeling analyses in some past
rulemakings, the Agency's risk assessment methodology has
evolved. In the two high-end parameter analysis for the
Petroleum Refining Waste Listing Determination placement of
the well on the centerline was chosen to be a high-end
parameter, and for the median value for this input
parameter, the well was placed one-half the distance from
the centerline to the edge of the plume.

EPA believes that well placement should be evaluated in the
sensitivity analysis, rather than placing the well on the
plume centerline in all cases, because this would result in
arbitrarily choosing this as one of the high-end parameter
assumption. 

I.A.6.f. Dispersivity

Comment 1: EPA's Dispersivity Value in the Groundwater
Model Is Inaccurately Calculated

As reported in both the 1995 and 1997 Background Documents
for the Groundwater Pathway, EPA has used the same values of
Dispersivity (longitudinal, transverse, and vertical) for
all simulations. EPA's calculation is based on the
longitudinal, transverse, and vertical dispersivity values
of 6.44 m, 0.805 m, and 0.04 m, respectively, which
represent approximately median values for a receptor well
102 m beyond of the down gradient edge of a 2020 m2
landfill. These values are inappropriate for the other
combinations of receptor-well distance and source area used
in the high-end analysis. Instead, the values of
dispersivity should be a function of the down gradient
distance from the center of the landfill. Using scale-
dependent dispersivities, API estimates that receptor-well
concentrations would be reduced by 40 to 60 percent. (API,
00009, pg 16)

Response: The commenter incorrectly assumed that the
saturated zone dispersivity values used in the groundwater
modeling analysis represent values for a landfill area of
2020 m2 and a receptor well distance of 102 meters. That
was neither stated in the 1995 Background Document nor in
the 1997 Background Document. The dispersivity values used
in the model were the median values based on a scale
dependent dispersivity distribution given by Gelhar (1992),
adjusted for landfill size and well distance. The landfill
areas varied from 40.5 m2 to 3.12 x 106 m2 (the range of 790
Subtitle D Industrial landfills in the U.S.). Well
distances varied between 0 and one mile.

Nevertheless, the Agency acknowledges that using the same
dispersivity values for different combinations of landfill
areas and well distances is not consistent with previous
modeling analyses. To respond to this comment, dispersivity
values in the current sensitivity analysis (see Additional
Groundwater Pathway Analysis, 1998) were properly adjusted
for landfill area and well distance. However, EPA does not
believe this had much impact on the modeling results.

I.A.6.g. Existing Groundwater Contamination

Comment 1: Failure to Consider Impacts of Existing
Groundwater Contamination

As acknowledged by EPA, and as further documented in this
portion of the comments, the subsurface under many
refineries is grossly contaminated. This existing
contamination affects the instant rulemaking in two
important ways. First, both the EPA and KGS modeling
assumes there is no existing groundwater contamination
contributing to the risks at the receptor wells. This
assumption is completely contrary to available information
on refinery sites. 

Under a plausible mismanagement scenario, particularly where
EPA is basing its onsite facility groundwater modeling on
hydrogeologic conditions at refinery sites, EPA is
obligated to consider all the important and relevant
subsurface conditions at these sites that may affect the
risks posed by improper waste management. Such conditions
include existing groundwater quality, especially where the
Agency can make generally applicable observations based upon
the extensive contamination throughout the industry. 
Therefore, since existing subsurface contamination can
contribute significantly to groundwater risks at the modeled
receptor well near refinery sites, EPA must include the
cumulative risks in its assessments and base its listing
determinations on such cumulative risks. This
identification and consideration of cumulative risks is not
only necessary to satisfy RCRA's protection of human health
mandate, but is otherwise required by Section 3-301(b) of
Executive Order 12898.

Second, the existing refinery groundwater contamination is
often in the form of NAPL, colloids, or other conditions
that can greatly facilitate the transport of contaminants at
refinery sites, including but not limited to the PAHs in
refinery wastes. Organic compounds exiting a waste
management unit can become dissolved into the more mobile
NAPL phase in the subsurface, and subsequently migrate with
the NAPL body. While the rate and extent of NAPL
migration can depend upon site-specific circumstances, NAPL
migration often results in lower dilution and attenuation,
and therefore higher receptor well concentrations, than the
typical dissolved-phased flow of contaminants. The Agency
recognized this phenomenon in the previous refinery waste
listing by assessing the mobility of benzo(a)pyrene (one of
the toxic PAHs of concern in the instant rulemaking too) as
"high" when released into substantially contaminated
subsurface environments, but "low" under other
circumstances.

However, EPA's groundwater model in the instant rulemaking
assumes the contaminants are mobile in the dissolved phase
only. Therefore, the model predicts contaminants are
subject to substantial dilution and attenuation in the
subsurface through the sorption of organic compounds. This
sorption is a function of a chemical specific soil-water
partitioning values indicative of conditions free of
cosolvents, surfactants, and NAPLs. Accordingly, EPA's
modeling substantially understates the concentrations of
contaminants that can reach receptor wells under the
groundwater conditions that prevail at many refinery sites. 

This failure to consider the free-phased flow of
contaminants due to existing NAPL and other contamination at
refinery sites is inconsistent with EPA's criteria for
listing hazardous waste. Under these criteria, the Agency
must consider the potential of hazardous constituents to
migrate under the plausible types of mismanagement to which
the waste could be subjected. 

EPA regards onsite landfilling and land treatment as
plausible mismanagement scenarios. Since the subsurface
under many refineries is contaminated with NAPLs and other
contaminants that can facilitate transport, and the onsite
units will not prevent the hazardous constituents from
reaching that subsurface contamination, EPA must take into
account the hydrogeologic conditions known to the Agency
that can facilitate transport of hazardous constituents.

While there is no formal nationwide survey of NAPL
occurrence at refinery sites, there is ample evidence that
NAPL contamination is frequent and severe. For example, in
October and November 1990, API conducted a survey to
determine the extent of free hydrocarbon recovery in the
refining, marketing, and transportation sectors of the
petroleum industry. Among the 42 refinery survey
respondents, there were 64 facilities with active
hydrocarbon recovery programs, indicating that sufficient
free-phase hydrocarbon existed in the subsurface at these
sites to warrant recovery by trenching or extraction.

The Los Angeles area provides another example of the
magnitude of LNAPL occurrence at refineries. Southern
California has numerous refineries, representing over 80
years of operations. These refineries were constructed in
the 1920s after oil was discovered on the Los Angeles
Coastal Plain. The location was considered convenient
because it was both near shipping corridors and near major
oil production fields. When the refineries were first
constructed, they were located in a Spanish Land Grant
District that was largely agricultural. Major population
centers have now encroached on these locations, and refinery
releases in the region pose a high risk of exposure.

In early 1985, oil droplets were evident on sand near a
high-priced beach just west of one refinery. The product
had leaked from the refinery and moved laterally toward the
ocean, following the regional groundwater gradient. About
6,000,000 barrels of product were estimated to exist beneath
the refinery.

Following this discovery, the California Department of
Health Services (DOHS) designated 17 refineries in the area
as health hazards. This designation reflected the potential
and actual subsurface occurrence of leaked hydrocarbon
product derived from these facilities.

As part of California Regional Water Quality Control Board
Order No 85-17, these refineries were ordered to delineate
LNAPL pools, including chemistry, areal extent, and total
volume. All 17 refineries were subsequently found to have
NAPL pools in the subsurface. Some of these pools are
extremely large, as indicated in the tables below.

A review of literature sources, materials from other RCRA
dockets, and RCRA Facility Assessments (RFAs) provided
additional information on NAPL contamination at seven
refineries. This information is briefly summarized in the
following tables and the subsequent three paragraphs.

Extent of LNAPL Contamination at Selected Petroleum
Refineries


Refinery Name
Estimated
Areal Extent
of LNAPL
(acres)
Minimum
Estimated
Quantity* of
LNAPL in the
Subsurface
(barrels)
Minimum # 
of 
 LNAPL
Pools
Maximum
Length of an
LNAPL Pool
(feet)


Chevron El Segundo
1,000
6,000,000
1
2,400


Rancho San Pedro
265
601,000
16
4,000


Amoco Mandan
120
NA
11
2,100


Navajo Artesia
NA
>110,000
2
3,000


Conoco Ponca City
52
NA
1
1,500


Sinclair Oil Tulsa
NA
> 130,000
1
na


Chevron El Paso
1,192
2,922,930
2
3,700


*where applicable, includes both LNAPL removed from
subsurface and estimate of volume remaining in subsurface.

 Nature of LNAPL Contamination Beneath Solid Waste
Management
 Units


Refinery Name
Minimum #
SWMUs 
Under-
lain by
LNAPL*
Min. Depth
to LNAPL
beneath a
SWMU (ft)
Max.
Apparent
Thick-ness
of LNAPL
beneath a
SWMU (ft)
Types of LNAPL
Beneath SWMUs


Chevron El Segundo
All
20
7
gasoline, kerosene
diesel


Ranch San Pedro
21
NA
NA
naptha, kerosene,
light gasoline


Amoco Mandan
12
5
10
naphtha, gasoline,
diesel


Navajo Artesia
1
10
up to
several feet
gasoline,
diesel


Conoco Ponca City
2
NA
15
gasoline


Sinclair Oil Tulsa
1
17
4-5
rude oil


Chevron El Paso
14
85
20
gasoline range


* Since wells were not always drilled directly through
SWMUs, units with LNAPL encounters nearby and upgradient are
included in this category.

Several additional observations from these source materials
are worth noting. In several instances, LNAPL has
migrated offsite. At the Sinclair Oil refinery, LNAPL
contamination was discovered when drinking water wells for
nearby residences were found to contain gasoline, thereby
dramatically illustrating the potential for NAPL plumes to
reach receptor wells. In all cases for which the extent of
LNAPL was mapped, the length of the pools extends further
than EPA's modeled median and high-end distances to the
receptor wells.

At the AMOCO refinery, the LNAPL plume was moving at the
rate of 584 ft/yr, and at the Chevron refinery, the plume
was moving at a rate of 182.5 ft/yr. These velocities can
be compared to the 36.4 ft/yr groundwater velocity in EPA's
deterministic run modeling. Nearly all of the extensive
floating hydrocarbon plumes were composed of lighter
petroleum fractions (gasoline, kerosene) which are more
mobile in the subsurface than the heavier fractions such as
crude oil. 

Significantly, the largest LNAPL pools are often composed of
many separate spills that have coalesced in the subsurface. 
Accordingly, compounds that are initially part of a small
pool with insufficient volume to travel very far may still
be transported great distances as pools coalesce.

Finally, the literature also contains studies of abandoned
refineries. Since the activity periods of many operating
refineries extend back over the same time period as the
abandoned facilities, the practices that occurred at
abandoned refineries are also likely to have been historical
practices at active refineries. The prevalence of LNAPL in
groundwater at abandoned refineries can therefore provide
additional evidence regarding the plausibility of LNAPL at
active refineries.

Spruill investigated the impact of waste areas at an
abandoned oil refinery site in the Arkansas River Valley and
noted that nonaqueous-phase organic liquids associated with
petroleum sludge wastes were distributed heterogeneously
throughout the site. An oil sheen was observed in most of
the monitoring wells, suggesting that floating oil and
gasoline hydrocarbons occur beneath much of the site. 
Oil-soaked soil was noted during the drilling of all but one
monitoring well.

Battermann and Meier-Lohr discuss an abandoned refinery site
at which 2,000 metric tons of gasoline-range LNAPL covered
an area of about 17 acres.

The 215-acre Old Citgo Refinery, located near Shreveport,
Louisiana, is an abandoned oil refinery on the National
Priorities List. This refinery has a floating, free-phase
hydrocarbon plume with an areal extent that is not yet fully
defined. In 1990, 47 families were evacuated from nearby
apartments due to health hazards from methane and
hydrocarbon fumes originating from the groundwater zone
beneath the refinery. Other area residents have reported
hydrocarbon seepages in their yards.

At an unnamed 60-acre abandoned refinery in the Midwest, an
LNAPL zone 2,400 feet in lateral extent and about 0.5 ft
thick was found floating on a water table only 5 feet below
ground surface. The floating hydrocarbon was discovered
during the late 1970s when adjacent residents began to
complain that shallow irrigation wells smelled like
gasoline. Despite long-term efforts to remove this
hydrocarbon from the subsurface, the off-site portion of the
LNAPL plume is still extensive and mobile.

At an unnamed abandoned refinery in the southern U.S.,
product seeps to a canal led to a comprehensive groundwater
investigation. Numerous distinct pools of different
petroleum products, including gasoline, kerosene, and crude
oil, were found to be floating on the water table beneath
the refinery, suggesting multiple releases. The LNAPL
thickness was highly variable and ranged from a light sheen
to several feet of product.

In summary, extensive groundwater contamination at many
refinery sites is well documented. Where EPA's onsite
groundwater modeling is intended to reflect hydrogeologic
conditions at refinery sites, EPA cannot ignore
hydrogeologic conditions such as existing subsurface
contamination that can both contribute significantly to
risks at receptor wells and facilitate the transport of
toxic contaminants released from waste management units or
practices. Even assuming arguendo refinery waste
co-disposal management practices will not result in the
free-phased flow of contaminants from the disposal unit, EPA
is
obliged to consider the plausible scenario of subsurface
free-phased flow arising from waste constituents reaching
existing NAPL pools and other migratory enhancing
contamination conditions in the vadose zone or the water
table. (EDF, 00006, pg 19)

Response: (See also Response to Comments 7.a (no free oil in
waste) and 8.f (incremental risks assessed) in Section
I.C.1.)

The Agency believes that its groundwater pathway analysis is
adequate and that the release of constituents via NAPLs is
not a concern for two reasons:

(1) A modeling analysis conducted in support of the 1995
 Proposal (see Background Document for Groundwater
 Pathway Analysis, USEPA, 1995) showed that crude oil
 tank sediment was not likely to exit the landfill, and
(2) An analysis of crude oil tank sediment samples
 conducted by EPA showed that even without deoiling, no
 free liquids were reported by the samplers or the
 laboratory (see response to comment 7a in Section
 I.C.1.)

EPA agrees that there are no doubt petroleum refineries at
which significant LNAPL contamination from product spills
exist, however the Agency does not believe this would
necessarily have a significant impact on its listing
decisions for several reasons. EPA cannot conclude that
LNAPLs would be present at the precise sites where these
wastes are likely to be disposed and potentially release
constituents. As the commenter also noted, the rate and
extent of NAPL migration can depend upon site-specific
circumstances. The proper consideration of existing
contamination would call for the full analysis of many other
site-specific factors as well, some of which may tend to
reduce constituent release from landfills, subsurface
transport, and human exposure. Such factors would include
the possible lack of potable groundwater near the site. 
Further, if LNAPL or other contamination exists, there may
well be on-going remediation, perhaps involving groundwater
interception or pumping that would significantly limit
groundwater flow. The Agency believes that a more
site-specific assessment would be more appropriately carried
out
by State or Federal programs related to remediation of
sites, and that such an approach would be quite difficult to
follow in pursuit of an industry-wide listing determination.

EPA also notes that it is not likely that aquifers so widely
contaminated so as to have floating hydrocarbons would be a
continuing source of drinking water. Such contamination
should be easily detected and avoided, and would be unlikely
to lead to the multiple-year transport and exposure scenario
that is the basis for EPA's risk assessments. Furthermore,
the level of benzene in likely sources of LNAPLs, gasoline
(1.6 % average, or 16,000 ppm), would dwarf any potential
risk that might arise from the leachable levels of benzene
in wastes under consideration in this rule, making any
concept of cumulative risk difficult to apply in any
meaningful way in a listing determination. As noted above,
the commenter's approach also presumes a number of
additional worst-case assumptions (regarding the presence of
critically placed NAPLs) that cannot be considered in a
vacuum. 

The Agency notes that the practical impact of considering
LNAPLs and facilitated transport, even if this could be
done, is not likely to be significant for most wastes of
concern. EPA has decided to list the wastes with higher oil
content (CSO tank sediment and crude oil tank sediment), as
well as the spent catalysts. Thus, the wastes for which
this comment is most relevant are being listed, leaving
unleaded gasoline tank sediment and HF alkylation sludge as
the only other wastes that showed any groundwater risk of
concern to the commenter. EPA notes that the effective
dilution and attenuation factors for benzene resulting from
the modeling (DAF; calculated by dividing the TCLP input at
the point of release from the landfill by the projected
concentration at the receptor well) for both of these wastes
were on the order of 2 to 4 (see Additional Groundwater
Pathway Analysis, 1998). These low DAFs approach the
theoretical limit of one, which mean that benzene released
from the landfill is estimated to reach the receptor well at
concentrations that approach the levels in leachate
released. Therefore, it is highly unlikely that EPA's
assessment significantly understates groundwater risks for
these wastes, and any further considerations in the modeling
(such as "facilitated transport" due to existing
contamination) are unlikely to significantly alter the
modeling results.
I.B. Supplemental Background Document: Non-groundwater
 Pathway Risk Analysis: Petroleum Refining Process Waste
 Listing Determination

Comment 1: The NODA Non-groundwater pathway risk assessment
consists of land treatment modeling only. Further, as
discussed in this portion of the comments, the modeled
wastes and their associated quantities, and the land
treatment unit sizes, were so arbitrarily small that the
risk assessment does not reflect plausible mismanagement
scenarios consistent with industry practices.

The underlying methodology flaw with the NODA LTU Risk
Assessment is the assumption that the land treatment
practices reported on the EPA surveys for 1992 are the only
plausible mismanagement scenarios the Agency should
evaluate, because such practices will not vary over time. 
In most cases, EPA mechanically applies the data reported
for 1992 without consideration of whether the data
adequately represent the only plausible mismanagement
scenarios that warrants modeling.

Consequently, the waste volumes modeled in the NODA LTU Risk
Assessment are grossly inappropriate for at least three
reasons. First, the median and high-end individual waste
volumes modeled for land treatment are typically much
smaller than modeled for landfilling, sometimes orders of
magnitude smaller, even though there is no legal or
technical bar for the wastes to be managed in either fashion
during any given year. The fact that refineries relied
upon land treatment less in 1992 is not necessarily
indicative of future practices. 

API's residual reports demonstrate the fallacy of EPA's
reasoning in this regard. At least 30 refineries practice
land treatment. While some use the practice for only one
waste, others rely on land treatment to dispose of 9-12
waste streams. An average of 581,666 MT of refinery wastes
were land treated annually from 1991-1993. 

API reported 11,612 MT of nonleaded tank bottoms and 4,098
MT of "other oily sludges and organic wastes" were land
treated in 1992, the year covered by EPA's Section 3007
survey. However, in 1993, API reported 14,215 MT of
nonleaded tank bottoms and 35,837 MT of other oily sludges
and organic wastes were land treated in 1993. 
Significantly, these sharp increases in land treatment
volumes from one year to the next were associated with the
same number of reporting entities for "other oily "sludges"
and only one additional reporting entity for nonleaded tank
bottoms. Therefore, on a per facility basis,
substantially larger volumes of these wastes were land
treated in 1993, as compared to EPA's 1992 survey year. 

Ironically, API recognizes the large potential for land
treatment volume fluctuation for individual refinery wastes
from year to year. Explaining these "fluctuations that
occur among the various streams", API stated:

 It appears that fluctuations in streams undergoing
 land treatment is not a simple trade-off among
 residual streams within a facility that has an
 operating land farm, but a more complex and
 dynamic phenomenon that involves the type of
 residual, its regulatory status and the facility's
 resources.

Therefore, given the importance of land treatment as a
management practice generally, and the recognized annual
land treatment volume fluctuation from year to year, EPA
must reasonably project that median and high-end waste
generation values can be managed via land treatment or
landfilling, and model both practices accordingly. (EDF,
00006, pg 50)

Response: The Agency used data collected for this
rulemaking as a basis for waste stream quantity assumptions. 
There is no reason to assume that 1992 is an aberrant year
and not representative of the industry over time. EPA
conducted an extensive survey of the industry,
characterizing waste generation and management practices in
1992. Based on EPA's assessment of the economic factors
affecting the refining industry and practices observed
during the Agency's field investigation, 1992 was a
typical year for refinery operations (e.g., the National
economy was not in extremis, capacity rates were high, plant
closings and openings were within normal ranges). See
also Section III.I, Comment 2 of the Proposal Response to
Comments Background Document.

For a discussion of the interchangeability of landfills and
land treatment units, see the Agency's response to Comment 5
in Section III.I of the Proposal Response to Comments
Background Document.

Comment 2: Moreover, EPA's modeling assumes no background
or other contaminant exposure to nearby receptors, an
unjustifiable assumption given the other waste management
occurring at these facilities, the pre-existing
contamination at many refineries, and the routine and
accidental releases associated with refinery operations. 
The Agency's failure to consider cumulative exposures to
nearby human populations violates RCRA and Executive Order
12898. (EDF, 00006, pg 55)

Response: The Agency does not believe this is appropriate
to consider for this listing for several reasons. First,
EPA does not have the type of specific information on off-
site contamination that would be required, nor did the
commenter provide any. Furthermore, without extensive
site-specific data, EPA cannot conclude that existing soil
contamination would occur at the same off-site locations
that might be impacted by releases from landtreatment units
containing the wastes under study. The proper consideration
of existing contamination would call for the full analysis
of many other site-specific factors, some of which may
reduce constituent release, transport, bioaccumulation, and
exposure. Such factors include specific landtreatment unit
design, the direction of any slope from the unit, the
existence of downgradient residential receptors, and
corrective action requirements that may lead to clean up of
any release.

Comment 3: In summary, the NODA LTU Risk Assessment does
not evaluate meaningful plausible mismanagement scenarios
because the wastes volumes, landfill areas, and hazardous
constituents modeled were far too limited to reach any
conclusions about potential risks to human health and the
environment. The risk assessment should be completely
revised to reflect projected mismanagement scenarios that
include waste volumes that could be land treated in any
given year (including codisposed wastes not covered by the
listing determinations or the associated study), standard
unit dimensions based upon existing and potential unit
sizes, an evaluation of all hazardous constituents that may
pose significant risks, and cumulative risks contributed by
land treatment and other sources at the facilities. (EDF,
00006, pg 55)

Response: The approach of realistic management scenarios has
been adopted in response to the court decision reached in
the suit contesting the carbamate listing determination
(U.S. Court of Appeals for the District of Columbia Circuit. 
1996 Dithiocarbamate Task Force, Petitioner v. Environmental
Protection Agency, et al., Respondents; Uniroyal Chemical
Company, Inc., and Zeneca, Inc., Intervenors Consolidated
with Nos. 9501251, 95-1253, 95-1255. Nov.1).....

I.B.1. Eliminating Wastes Managed as Hazardous

Comment 1: EPA "recalculated" the waste volumes to exclude
wastes managed as hazardous in 1992. This recalculation
affects crude oil storage tank sludge most dramatically. 
The NODA modeled land treatment high-end annual volumes for
this waste were 181 MT onsite and 100 MT offsite, as
compared to 632 MT in the landfill modeling, and 1,839 MT in
the 1995 LTU risk assessment (onsite). 

These "recalculations" are apparently based upon the
unverified and insupportable assumption that simply because
certain wastes were managed in 1992 as hazardous, they will
always be managed as hazardous. This assumption is
insupportable because EPA is unaware of whether the waste
actually exhibited the toxicity characteristic for benzene,
or the refinery operator simply chose to manage the waste as
hazardous that year for convenience or some other reason. 
Moreover, assuming arguendo that the waste exhibited the
toxicity characteristic that year, EPA has no information
that this same sludge will always exhibit the toxicity
characteristic for benzene, particularly given the
inconsistency of the TCLP on oily wastes and the highly
varied deoiling techniques applied to these wastes as
discussed above.

In addition, by excluding wastes that happened to be managed
as hazardous in 1992, EPA is implicitly relying on the
existing toxicity characteristic in lieu of listing the
waste, and therefore making the same policy errors as the
landfill TC Capping modeling discussed above in Section II.J
of the comments. The enforcement difficulties associated
with this approach, the implications for air drying wastes,
and other factors strongly favor listing these wastes rather
than relying upon the existing characteristic to protect
human health and the environment. (EDF, 00006, pg 52)

Response: EPA does not agree with this comment. The wastes
that were excluded for the revised land treatment modeling
were, in fact, reported to be hazardous in the 3007
Questionnaire. While there may well be variability for some
wastes in when they exhibit a characteristic, EPA has no
reason to believe that 1992 was not a typical year, or that
such variation would lead to significant changes in the risk
analysis. While excluding these volumes does rely on the
characteristic as the commenter noted, this reliance seems
justified because these waste did, in fact, exhibit the
characteristic and were managed as hazardous. Furthermore,
EPA notes that the waste of concern to the commenter, crude
oil tank sediment, is being listed as hazardous in any case
due to groundwater risks from landfill disposal. For the
other wastes modeled in landtreatment units, removal of
volumes regulated as hazardous did not alter the risk
results significantly, i.e., the median and 90th percentile
volumes were only slightly different (see Table 2.1 in the
NODA nongroundwater risk assessment background document,
Supplemental Background Document; Nongroundwater Pathway
Risk Assessment, March, 1997).

I.B.2. Model Modifications Regarding Release and
 Transport of Soil to Off-site Receptors

Comment 1: EPA Failed to Adequately Respond to NPRA's
Comment That the Runoff from a Land Treatment Unit Can Not
Physically Reach the Home Gardens as Described in the
Technical Documents. 

In the original comments, NPRA stated that the methodology
for computing runoff from landfills containing Clarified
Slurry Oil Sediment which would reach "home gardeners" was
faulty. NPRA asserted that it was not physically possible
for the runoff to reach the home garden and therefore there
was no direct or indirect risk to the home gardener.

In the NODA, EPA responded to NPRA's and others comments by
revising its overland transport equations. Although EPA
made changes to these equations, it did not address the
fundamental question how can the runoff reach the home
garden given the roads, ditches, buildings, and management
controls between the land treatment unit and the home
garden?

In response EPA merely: 

 Acknowledged that the USLE equation it used "estimates
 only soil erosion to waterbodies." Then, EPA defined a
 new setting for the analysis so that it could use the
 equation. The new setting for the analysis is shown in
 Figure 3-11 of the document Supplemental Background
 Document for the Non-groundwater risk Assessment for
 the Petroleum Waste Listing Interim Notice of Data
 Availability. It places the receptor (home garden)
 between the landfill and the waterbody.

 Assumed that "the sediment not reaching the waterbody
 is considered to be deposited evenly over the area of
 the subbasin." This assumption means that EPA believes
 that water runoff acts like air and therefore it is
 reasonable to assume that a uniform deposition of
 runoff over the nonwater body subbasin is possible.

NPRA's response to EPA's revision of the methodology is as
follows:

 Although EPA made changes to the methodology, it did
 not address a fundamental principle of the methodology
 which concerns the flow (i.e. pathways) of runoff from
 the land treatment units to the residential plot or
 vegetable garden.

 The assumption that runoff from landfills can be
 modeled as uniform deposition over the subbasin has no
 scientific, technical or legal basis. Any runoff
 (water) from the land treatment area would flow in
 channels and would not flow uphill over ditches, roads,
 and other natural barriers to reach the residential
 plots or vegetable gardens. (NPRA, 00004, pg 4)

Response: Listing determinations estimate risk that might
reasonablely be expected to occur at existing or future
petroleum refining locations. Fate and transport modeling
conducted for this purpose must estimate risk for present
conditions and predict risk for future conditions. Soil
erosion models that include channeling require extremely
detailed site descriptions. Simplifying assumptions are
required to estimate soil erosion applicable to many
possible scenarios. With the USLE it is possible to
estimate the quantity of contaminated soil which leaves the
LTU and the quantity of soil expected to be delivered to
the nearby water body. Using the equations used in this
risk assessment it is assumed that the soil that does not
arrive at the waterbody is spread evenly over the area
between the LTU and the water body. Until a better model is
available this estimation will be used to estimate the risk
due to soil erosion. Significantly, due to an error in the
air dispersion modeling conducted for the proposal, the
percentage of total risk attributable to the air pathway has
increased and is now the same order of magnitude as the risk
due to soil erosion. Upon reexamination of the air pathway
analysis, it was discovered that a unit conversion from
g/m2 to g/m2 was performed in two locations, creating an
underestimation of risk due to air deposition of 6 orders of
magnitude. The unit conversion correction makes the risk
due to air deposition from windblown soil from the LTU the
same order of magnitude as the risk attributed to soil
erosion in each case; i.e., if the risk due to soil erosion
is in the range of 10E-6, the risk due to air deposition is
also. Consequently, USLE modeling is less critical for the
listing determination. Table I.B.1 compares the
contribution to the media concentrations of contaminants
from air and erosion as investigated in the uncertainty
analysis conducted in support of this listing determination. 



Table I.B.1. Risk to Home Gardener from the Onsite Disposal
of Clarified Slurry Oil Sludge
Comparison of Risk Due to Air Deposition and Soil Erosion
Pathways

Constituent Total Risk Risk Due to Risk Due to
 Air Deposition Erosion
 
Benzo(a)pyrene 6.6E-06 3.3E-07 6.3E-06
 
Dibenz(a,h) 1.9E-05 1.5E-05 4.5E-06
anthracene

Methyl 1.9E-05 1.4E-06 1.8E-05
cholanthrene, 3- 

Benz(a) 2.6E-06 1.8E-07 2.5E-06
anthracene

Dimethylbenz 5.3E-05 5.2E-05 7.9E-07
(a)anthracene, 7,12-
 
Indeno(1,2,3-cd)9.5E-08 2.2E-09 9.3E-08
pyrene 
 
Benzo(b) 1.0E-06 2.0E-07 8.3E-07
fluoranthene 
 
Benzo(k) 6.2E-07 2.4E-08 6.0E-07
fluoranthene

Chrysene 3.3E-07 1.8E-08 3.2E-07
 
Total Risk 1.0E-04 6.9E-05 3.4E-05
for Gardener

Comment 2: EPA Failed to Include Management of Refinery
Residuals in its Revised Estimates of Population Risks.

EPA did not consider the controls at the land treatment
areas described by NPRA in its original comments as examples
of management at land treatment areas. EPA specifically
requested this information from NPRA. The management of
these land treatment units significantly reduces the
potential for any runoff to flow from the site. There is no
justification for ignoring this relevant information by EPA. 
(NPRA, 00004, pg 4)

Response: EPA did not ignore this information. However, it
is not possible to confirm the effectiveness of controls.
Therefore, EPA has assumed that in most cases (central
tendency) controls are present and 50 percent effective and
in a few cases (95th percentile) no controls are present or
are ineffective in preventing erosion.

Comment 3: EPA Has Overestimated Population Risks for Land
Treated Residuals

EPA also has overstated the size of the potentially exposed
populations for land treated residuals. EPA estimated the
population of adult residents and home gardeners based on
the assumptions that 38 percent of the population are home
gardeners and that the total population lives within 300
meters downhill of a land treatment unit. As discussed
earlier, the adult resident and home gardener exposure
scenarios are fundamentally flawed and lead to substantial
overestimates of individual and population risks. Specific
flaws in the model that result in overestimates of risks are
described in the following five comments. (API, 00009)

Response: Population risk is attributable to air dispersion
and deposition pathways as well as soil erosion. Since, as
discussed in comment 1 of this section, the risk from the
air pathways has increased by 6 orders of magnitude,
population risk can be assumed to have increased
significantly. EPA responds to comments on population risk
in Section IV.B.

Comment 4: EPA Assumes that Run-on/Run-off Controls Do Not
Adequately Capture Sediments Originating at a Land Treatment
Unit (LTU) 

LTUs are essentially bioreactors using soil as a support
medium for bacterial populations that
degrade oily materials. Proper operation of LTUs requires
the control of run-on in order to prevent unwanted sediments
and water from entering the units. As discussed Supra, data
provided by EPA clearly document that run-on/run-off a
controls are in place at all LTUs currently receiving
refinery residuals (Vierow, 1995). This assumption is not
appropriate when calculating population risks. In the case
of population risks, any reduction in run-off from adequate
controls will result in an overall reduction in the
population risk.

The implausibility of the assumption that run-on controls do
not adequately capture sediments is also demonstrated by the
fact that run-on/run-off controls at LTUs do not have to
achieve 100 percent control of sediments in order to reduce
risks from the resident or home gardener exposure scenarios. 
Because run-off from a LTU is likely to be quickly
channelized, the controls only have to direct the run-off
into a common ditch and produce a channelized flow to
prevent the scenario modeled by EPA, as discussed below. As
a result, the vast majority of LTUs are not expected to
affect off-site residential properties. (API, 00009)

Response: There are no data to document the presence, design
parameters, and effectiveness of run-off controls. The
Agency has assumed for central tendency that controls are
present and reduce run-off by 50 percent and for the high
end (95th percentile) case that controls are absent or do
not reduce run-off at all. Again, the revised air pathway
results make assumptions regarding the adequacy of run-off
controls less critical to the listing determination.

Comment 5: EPA Assumes that Run-off from the Land Treatment
Unit Does Not Channelize, but Uniformly Flows Across a
Residential Plot

As discussed Supra, EPA's assumptions for overland flow are
clearly unsupportable. EPA has assumed that run-off moves by
overland or sheet flow from the LTU directly to a
residential plot or vegetable garden. Overland sheet flow
is unlikely to occur because surface water run-off rapidly
channelizes into streams that travel by means of swales or
gullies and are intercepted by other bodies of water. 

Overland or sheet flow is a phenomenon that occurs only over
short distances. In the population risk assessment, EPA
assumes that overland flow continues for 300 meters. In
addition, the analysis implicitly assumes that overland
flows crosses multiple properties and reaches all
individuals 300 m down gradient of the LTU. In reality,
properties will be generally separated by fences or
landscaping, which can effectively prevent significant run-
off from moving between properties. At most, therefore, the
size of the population exposed should be limited to the one
or two properties directly adjacent to the LTU. (API,
00009)

Response: Listing determinations estimate risk that might
reasonablely be expected to occur at existing or future
petroleum refining locations. Because fate and transport
modeling conducted for this purpose must estimate risk for
present conditions and predict risk for future conditions,
sufficiently detailed site descriptions are not available
for use in soil erosion models that include channeling. 
Simplifying assumptions are required to estimate soil
erosion applicable to so many possible scenarios. With the
USLE it is possible to estimate the quantity of contaminated
soil which leaves the LTU and the quantity of soil expected
to be delivered to the nearby water body. Using the
equations used in this risk assessment it is assumed that
the soil that does not arrive at the waterbody is spread
evenly over the area between the LTU and the water body. 
Until a better model is available this estimation will be
used to estimate the risk due to soil erosion.

Comment 6: EPA Assumes that Residences Are Directly Down
gradient of Land Treatment Units
 
As discussed above, overland transport of run-off will
revert to channelized flows when the overland flow reaches
any obstruction or if the ground surface begins to go uphill
(creating a small valley or swale). Thus, the existence of
a ditch, fence, wooded area, road, building, or swale
between the landfarm and a garden eliminates this pathway of
exposure. In the assessment, however, EPA assumed that no
such obstructions occurred between any of the nearest
residential properties and the LTU. Again, this assumption
has likely led to an overestimate of the population
potentially exposed. (NPRA, 00004)

Response: Due to the scope of the rulemaking, it is not
possible for the Agency to make site specific findings
regarding the existence of actual obstructions that may
reduce or prevent soil erosion to a receptor. In the
absence of specific data regarding the use and effectiveness
of run-off controls, EPA believes that its default
assumptions that controls are 50% effectiveness for central
tendency and are not present or ineffective for high-end are
reasonably conservative. 

Comment 7: EPA Assumes that Run-off Reaching Residential
Properties Will Reach Vegetable Gardens

EPA has assumed that overland flows reaching a residence
will also reach a vegetable garden (if one exists on the
property). However, even if a property receives overland
flow directly from a LTU and a vegetable garden exists at
the property, EPA should not assume that run-off will always
reach the garden. The garden may be located on the opposite
side of the property from the LTU, the presence of buildings
or paved surfaces may divert the run-off, or the garden
itself may have run-on controls to avoid flooding during
rain events. For these reasons, a substantial fraction and
perhaps a majority of gardens would not be affected by any
run-off reaching the residential property. It is not
appropriate to ignore this issue when estimating population
risks. (API, 00009)

Response: See response to comment 4 regarding run-off
control assumptions. EPA responds to comments on population
risk in Section IV.B.

Comment 8: EPA Assumes that there Is No Loss of
Contaminants During Preparation of Produce (i.e., Washing,
Peeling, or Cooking) 

EPA's assessment does not consider the loss of PAHs during
food preparation. It is well known that uptake of
lipophilic compounds by root crops is limited to the surface
of the crops (EPA, 1994). Therefore, any peeling or
cleaning of root vegetables would reduce or even eliminate
contaminant levels in the produce, thereby limiting
exposures via this pathway.

It is highly unlikely that EPA's assumptions hold true for
any of the land treatment units receiving refinery
residuals, since all of them reported some form of run-on/
run-off controls, and uniform sediment flow over any
substantial distance is improbable, if not impossible. For
these reasons the estimates of population risk contained in
the proposed rule are likely to be significant
overstatements of the actual number of individuals at risk
from landfarm releases. In addition, as stated earlier, the
overland flow models used by EPA are fundamentally flawed
and cannot provide meaningful estimates for either
population or individual risks for the adult resident or
home gardener scenarios.

In sum, population risk estimates associated with existing
management of the residuals indicate that there is no basis
for listing CSO sediment or the hydroprocessing catalysts. 
In contrast to EPA's findings in the proposed rule and NODA,
API believes most of the exposure pathways evaluated by EPA
are incomplete for the majority, if not all, of the
populations evaluated. While EPA's calculations of
population risks overstate potential risks, they are still
extremely low and clearly support a no-list decision for CSO
sediment and spent hydrotreating and hydrorefining
catalysts. Not only has EPA greatly overestimated the
actual risks, but the risks calculated are as low or lower
than previous policy decisions not to regulate. When the
risk estimates at issue are properly adjusted to eliminate
flaws in EPA's assumptions, the population risk is even
lower than EPA has calculated and makes the case for no-
listing even more compelling. (API, 00009)

Response: The uncertainty analysis conducted in support of
the listing determination have included distributions of
consumption rates for exposed fruits and vegetables and root
vegetables. The cooking losses estimated for exposed
fruits, vegetables, and root vegetables are approximately 20
percent as shown in Table I.B.2. This loss will not affect
the listing decision. 

Table I.B.2. Percent Loss During Preparation for Exposed
Fruits Vegetables and Root Vegetables.

Fruit % Loss
Apple 22
Pear 22
Peaches 24
Strawberries 10
Average 20

Vegetable % Loss
Asparagus 22
Cucumber 18
Sweet pepper 13
Tomato 15
Broccoli 14
Cabbage 11
Lettuce 22
Snap beans 18
Average 17

Root % Loss
Beets 28
Carrots 19
Onions 5
Potatoes 0
Average 17

See previous discussions of soil erosion and run-off
controls. EPA responds to comments on population risk in
Section IV.B.

Comment 9: The Model Used To Evaluate Overland Flow Should
Not Be Used To Evaluate Runoff from Land Treatment Units 

To evaluate overland flow from LTUs, EPA used the Universal
Soil Loss Equation (USLE) and a simple model of sediment
transport. API has evaluated this model, although there is
clear evidence that current run-on/run-off control practices
effectively limit overland flow. As implemented by EPA, the
model inaccurately evaluates run-off and is likely to
greatly overestimate the amount of residual that enters a
residential garden. First, the model assumes that surface
water run-off from a LTU moves by sheet flow to a
residential vegetable garden. Sheet flow of surface water
and the associated erosion typically occurs when rain falls
on sloping ground that naturally or artificially has been
smoothed. Such flow however, is inherently unstable and
occurs only over short distances (Brooks et al., 1991). In
most cases, surface water rapidly channelizes and even on
smooth slopes tends to form gullies if the substrate has
minimal vegetation. Channelization of sheet flow will also
occur when the sheet flow encounters the first swale or
ditch. Once surface water is channelized it does not tend
revert back to sheet flow under non-alluvial conditions.

Second, the model assumes that the fraction of the soil
delivered to the garden is based on the percentage of the
sheet flow that is intercepted by the garden plot. Because
the water is likely to be channelized, the percentage of
runoff intercepting the garden plot should be extremely
small. As currently modeled by EPA however, all runoff is
expected to be sheet flow. The interception of runoff
between the LTU and the residential garden, therefore, is
mostly a function of the size difference between the two
areas. Finally, EPA has failed to acknowledge that once the
soil from the landfarm enters a stream it potentially
becomes mixed and diluted with sediment and runoff from
other areas. Such dilution would greatly reduce the
residual concentration reaching the residential garden
located within the discharge area. For these reasons, the
model used to estimate overland transport of sediment must
be viewed as implausible and should be replaced by a more
realistic model, in accordance with 40 CFR 
261.11(a)(3)(vii). (API, 00009, pg 17)

Response: EPA agrees that the USLE model is simplistic and
a more realistic model would be desirable. However, no
other model is currently available. It is impossible to
obtain sufficient site specific data for using models that
predict runoff using rills and channels and to have that
data be applicable to all current and future management
units. Although EPA realizes the short comings of the USLE,
it is the only model that can be used to predict erosion
from a field to a water body in a non-specific setting as
required for listing decisions. It is unlikely that this
change in the model would change the listing decisions for
CSO sludge however, because, the contribution by the air
pathway alone is sufficient for listing CSO sludge. 

Comment 10: Clarification of the Sediment Delivery Ratio
Derivation Is Required

The descriptive information provided in Section 3 of the
Supplemental Non-groundwater Background Document concerning
the derivation of the sediment delivery ratio (SDR) is
limited, with Table A-1.4 suggesting that the equation and
its variables were empirically derived. The model implies
that the value for (SDR) should be between 0 and 1, which is
also consistent with the definition of SDR from the
Universal Soil Loss Equation:

 "The sediment delivery ratio is the ratio of
sediment delivered at a watershed outlet to the gross
upland erosion." (Corbett, 1995, p. 7.67).

Recalculation of the SDR using the equation provided in A-
1.4 yielded values greater than 1. Review of the input
values for this equation showed that units were not
specified for sub-basin 
areas in the table labeled "Values for Empirical Intercept
Coefficient, a" (although the footnote suggests that the
units are in square miles). 

When different sub-basin areas are substituted into the
equation for sub-basin areas less than 10 mi2, the
calculated SDR values exceeded 1. Such a finding is not
consistent with the definition of this term. The equation
should be re-examined since it affects the soil load runoff
(e.g., SL0,F and SLBF) which in turn affects the off-site
soil
concentrations (CR) used in the risk assessment. (API,
00009, pg 18)

Response: The units for the area of the subbasin are in
square meters not in square miles. The equation may indeed
fail for areas smaller than 10 square meters, but LTUs will
always be larger than this.

Comment 11: Incorrect Calculation of the Unit Soil Loss
from the Source (Xe,s) May Result from the Inappropriate Use
of Default Values

In several instances, the parameter values used by EPA to
evaluate soil loss are inconsistent between and within
equations. First, values used for the USLE rainfall factor
(RS) are not consistent with central tendency or high end
distributions. The RS values used for central tendency and
high end (428 and 50 yr-1, respectively) in Table A-1.3 do
not appear to represent these descriptors. The value of 428
yr-1 is consistent with heavier rainfall areas such as the
southeastern US, while the value of 50 yr-1 is consistent
with central and western central U.S. (Corbett, 1995). 
Since there is a direct relationship between unit soil loss
and the rainfall factor, at a minimum these values appear to
be reversed. In addition, some consideration should be made
to use a value from 100 to 150 yr-1 for central tendency. 

Second, the USLE supporting practice factor (PS) used to
compensate for different erosion control measures employed
at the source area (Table A-1.3 (PS = 1)) (Corbett, 1995) is
extremely conservative and assumes that no erosion control
measures (e.g., berming) are employed at the LTU. Berming
and other runoff control measures would reduce the amount of
solids transport from the LTU since the soil concentration
at the receptor (CR) is proportional to the value of PS. 
Typical engineering control practices should yield a Ps
value of 0.25 (since run-on and run-off controls are assumed
to reduce risks by approximately 75 percent) for most LTUs. 
(API, 00009, pg 18)

Response: The central tendency location was originally
chosen on the basis of air modeling considerations. For
this reason Houston was selected as the central tendency
location. However, when soil erosion was considered it
became a high end location for soil erosion. This is no
longer an issue because for the uncertainty/variability
analysis conducted in support of the risk assessment each
nonhazardous LTU managing each waste stream is modeled using
meteorologic data, soil data, and USLE parameter values
specific to the geographical location. This analysis has
shown that the listing decision is not altered by the use of
more site -specific data.

See previous responses for reply to comments on runon/
run-off controls.

Comment 12: The Constituent Loss Constants May Be
Incorrectly Calculated Due to Selection of Variable Terms

In the selection of constituent loss constants, EPA has
incorrectly selected sample specific characteristics for
different soil types within the same equation in Table
A-1.3.
The value used for the USLE soil erodability factor Ks
(0.37) was consistent with a silty clay loam containing
0.05% organic matter (Corbett, 1995). In Table A-1.17, the
value for Ks (saturated hydraulic conductivity) was
consistent with a silty sand, while the value for b (soil-
specific exponent representing water retention) was
consistent with a loam, and s was consistent with a sandy
clay (EPA 1988). None of the recommended values represented
the median value for their respective distributions. The
soil type should be consistent (e.g., silty clay loam) for
all input values. (API, 00009, pg 19)

Response: The uncertainty/variability analysis conducted in
support of the non-groundwater risk assessment modeled each
nonhazardous LTU using meteorologic data, soil data, and
USLE parameter values specific to the geographical location
of the unit. This analysis has shown that the listing
decision is not altered by the use of more site-specific
data. See Table B.1.3 for soil parameter values at these
nonhazardous land treatment units.

Table I.B.3. Soil Parameter Values for Geographic Locations
of Concern


State
County
Site
Soil Texture
Layer Depth (cm)
Bulk Densitya (g/cm3)
Sat. Vol. Water Contentb
Sat Hydraulic Conductc
Soil Specific Exp (b)d
Range in Organic Matter %
Fraction Organic Carbone


WA
Sakit
Anacortes
Silt Loam
18
1.02
0.45
0.45
5.3
5.0-10.0
0.035


WA
Whatcom
Blaine
Loam
18
1.00
0.43
1.04
5.39
4.0-10.0
0.040


LA
Iberville
White Castle
Clay
64
1.35
0.38
0.20
0.42
0.9-3.5
0.015


TX
Nueces
Robstown
Clay
66
1.35
0.38
0.20
11.40
0.9-3.5
0.015


NM
San Juan
San Juan
Sandy Loam
10
1.48
0.41
4.42
4.9
1.0
0.01


UT
Salt Lake
Salt Lake City
Loam
20
1.26
0.43
1.04
5.39
2.0-4.0
0.015


a MUIR Database
b Carsel and Parrish (1988) Table 2 
c Carsel and Parrish (1988) Table 4
d Clapp and Hornberg (19) Table 4
e Calculated using equation 6.5 in MULTIMED documentation
(p. 92)


Comment 13: EPA Has Not Fully Accounted for the Use of
Run-on/ Run-off Controls at LTUs

In response to comments, EPA appropriately removed hazardous
waste land treatment units receiving CSO sediments from the
risk assessment. The risks to home gardeners and adult
residents were instead based on potential runoff from land
treatment units receiving only nonhazardous wastes. 
Although the analysis was restricted to nonhazardous land
treatment units, EPA has inappropriately assumed that the
nonhazardous LTUs do not use run-on/run-off controls. This
assumption is in clear contrast to EPA's own data (Vierow,
1995) which reports that all LTUs responding to the RCRA
3007 survey use some type of run-on/run-off control. As a
result, the risk assessment conducted by EPA clearly
overestimates potential risks to adult residents and home
gardeners. (API, 00009, pg 19)

Response: See previous responses for discussion of soil
erosion and air deposition risks.

Comment 14: EPA Has Not Yet Addressed the Numerous Errors
in Its Risk Assessment for Home Gardeners

EPA's revised risk assessment does not address a number of
comments API made regarding the risk assessment for
consumption of vegetables assumed to be impacted by land
treatment unit runoff. EPA's revised assessment
appropriately included biodegradation of PAHs at the
receptor site and corrected the root vegetable consumption
rate; however, EPA did not correct its estimates of PAH
uptake by above-ground and root vegetables. Among the
errors documented by API in the comments on the proposed
rule are: overestimated vegetable lipid content used to
calculate PAH uptake from air; use of an inappropriate
regression to estimate the uptake of PAHs from air; failure
to use EPA's own recommended empirical reduction factors for
chemicals with low solubility and for root vegetables other
than barley; failure to incorporate an adjustment from dry
weight concentration to wet weight concentration for above
ground produce; and overestimation of the fraction of
consumed vegetables that are home-produced. Addressing
these errors would result in at least a 100-fold net
decrease in risks from vegetable consumption. (API, 00009,
pg 19)

Response: The uncertainty/variability analysis conducted in
support of this listing decision has addressed many concerns
expressed by this commenter. Measured air-to-plant
biotransfer factors are used for all constituents where
values are available. When measured values are not
available, a factor of 40 is included in the denominator of
the equation used to estimate the bioaccumulation factor as
suggested in the dioxin document (US EPA, Estimating
Exposure to Dioxin-Like Compounds, volume III, 1994). In
addition, a quantitative uncertainty analysis has been
conducted using a Monte Carlo simulation to address the
variability in consumption rates for fruits and vegetables
as presented in the 1996 Draft Exposure Factors Handbook
(U.S. EPA, Uncertainty Analysis: Nongroundwater Pathway Risk
Assessment; Petroleum Refining Waste Listing Determination,
1998). An adjustment factor (VGAG) has been incorporated
into the equations to address the overestimation for
lipophilic compounds (KOW >4). In this analysis, VGAG has
been assigned a value of 0.01 for all exposed fruits,
exposed vegetables, and root vegetables intended for human
consumption or a value of 1 for all forage crops. The VGAG
term was included in the original analysis as well.

Comment 15: EPA Did Not Revisit Population Risks in the
Revised Assessment

EPA's revised risk assessment for both groundwater and Non-
groundwater pathways did not include revised estimates of
population risks associated with management of refinery
residuals. As stated in previous API comments on the
proposed rule and in our present population risk discussion
(supra), EPA should consider population risks in its final
listing determination for refinery residuals. An elevation
in the theoretical individual cancer risk should not be
considered grounds for listing a waste as hazardous if the
incremental cancer cases avoided are essentially zero (as
demonstrated by proper population risk assessments). (API,
00009, pg 20)

Response: The increase in the proportion of risk due to air
dispersion and deposition will significantly increase the
population risk in the non-groundwater risk analysis. EPA
responds to comments on population risk in Section IV.B.

Comment 16: Sun Does not Believe that EPA has Justified
Listing of any Residuals.

The minor incremental cancer risks calculated using still
very conservative models do not justify a listing
determination for the three wastes proposed for listing. In
particular, as detailed in NPRA's comments, the EPA's Home
Gardener model assumptions are totally unreasonable and are
not based on actual land treatment unit design and
operational practices. (Sun, 00008)

Response: In the uncertainty/variability analysis conducted
in support of the non-groundwater risk analysis each
nonhazardous LTU managing the waste streams of concern are
modeled using meteorologic data, soil data, and USLE
parameter values specific to the geographical location where
the unit is located. In addition, variation in constituent
concentration, distance to receptor, and the distributions
of consumption rates and exposure durations presented in the
1996 Draft Exposure Factors Handbook are included in the
analysis. This analysis has shown that the listing
decision is not altered by the use of more site-specific
data.



I.B.3. Co-disposal

Comment 1: For the co-disposal land treatment scenarios, the
volumes modeled were minuscule compared to industry
practice. In the onsite case, three wastes were codisposed
with a combined annual total volume of 149 MT. In the
offsite case, two scenarios were modeled, and the highest
volume for these scenarios covered two wastes with a
combined annual total of 75.1 MT. 

Incredibly, these waste quantities are lower than the median
volumes for HF alkylation sludge (offsite) alone, and lower
than the corresponding high-end volumes for crude oil
storage tank sludge, HF alkylation sludge, and sulfuric acid
alkylation sludge, both onsite and offsite. Accordingly,
EPA's modeling presumes these wastes will never be
codisposed in a land treatment facility at these quantities
or higher. 

More importantly, the modeled co-disposal volumes should be
compared to the vast majority of the average annual 581,666
MT of land treated wastes reported by API from 1991-1993
that is managed onsite at 30 refineries, where 9-12
different refineries wastes are managed in the same units as
discussed above. Clearly, EPA's volume input parameters
do not reflect actual co-disposal on either a total volume
or number of wastes basis. By modeling only those
facilities reporting co-disposal in EPA's 1992 Section 3007
survey, omitting wastes that happened to be managed in
hazardous waste units that year, and omitting refinery
wastes other than those covered by this listing
determination (and an associated study), EPA's land
treatment co-disposal modeling fails to account for the vast
quantities of co-disposal actually taking place.

It should be noted that EPA's landfill modeling included a
co-disposal scenario for all wastes covered by the instant
rulemaking and the associated study. As discussed above,
EPA employed median annual landfilling volumes in the co-
disposal scenario, irrespective of whether that scenario was
observed at a particularly facility in 1992. While there
are still flaws in the landfill co-disposal modeling, as
discussed in Section II.E of the comments, at least in that
effort EPA attempted to project a plausible mismanagement
co-disposal scenario that was not so constrained by the 1992
survey data that the result was a completely meaningless
exercise. The inconsistency between the landfill and land
treatment co-disposal modeling approaches is additional
evidence of the inadequacy of the NODA LTU Risk Assessment.

With respect to land treatment unit dimensions, the Agency
once again assumes the units that happened to receive
certain wastes in 1992 represent the only plausible
mismanagement scenario for these wastes. Accordingly,
median onsite land treatment unit sizes are different for
every waste modeled, with areas ranging from 3 acres for HF
alkylation sludge to 15.8 acres for CSO sludge. In the
co-disposal scenarios, the onsite unit is 7.5 acres, based
upon the size of the one unit modeled. 

Since there is no legal or technical bar for an existing
land treatment unit to receive any refinery waste, or for a
refinery to construct a new land treatment unit to receive
any refinery waste, this modeling approach fails to account
for both present and potential mismanagement. There is
simply no legal or factual basis for EPA to conclude that
the only plausible mismanagement scenario for the land
treatment of HF alkylation sludge is in a unit 1/5 the size
of a unit used for CSO sludge. Under these circumstances,
EPA must project a standard onsite land treatment unit to
cover the full range of plausible mismanagement at refinery
sites. See also Section II.G of these comments for a
discussion of the analogous landfill modeling issue. 

Indeed, EPA recognizes the absurdity of its position when
modeling the offsite co-disposal scenario. In this
instance, EPA did not rely upon the size of the 1992 units
receiving certain wastes, but instead projected a standard
area size based upon all offsite units "because it would be
possible for refiners to send wastes to any nearby offsite
facility". Unfortunately, EPA did not apply this logic to
all the other onsite and offsite land treatment scenarios
modeled, even though in all cases future practices are
similarly not restricted in accordance with the data
reported for one year, particularly when the potential
construction of new units is considered. 

Two other flaws in the NODA LTU Risk Assessment warrant 
scrutiny. Only PAH constituents were considered in the risk
assessment co-disposal scenarios, therefore inhalation risks
posed by benzene and other volatile chemicals, or direct and
indirect risks posed by arsenic and other metals, were not
evaluated. The risks posed by these constituents may be
particularly important in a reasonable co-disposal scenario,
since the waste types and volumes involved would be much
larger than evaluated in the NODA effort. (EDF, 00006, pg
57)

Response: All chemicals in each waste stream and major
management practice combination were evaluated initially in
the bounding analysis in which all model parameters are set
at high end values. The bounding analysis showed PAH
compounds to be constituents of concern in land treatment
units and all other waste stream constituents and other
management practices to be below a level of concern. Only
those constituents and management practice combinations
showing risk in the bounding analysis were evaluated in the
more detailed risk analyses. PAH compounds in land
treatment units were identified as the constituents to be
evaluated in detail in this analysis. I.C. Supplemental Background Document: Listing Support
 Analyses: Petroleum Refining Process Waste Listing
 Determination

I.C.1. Analyses Regarding Leaching of Oily Waste

Comment 1: TCLP Leachate Concentrations are Fundamentally
Inaccurate

Comment 1.a: EPA used TCLP results from waste samples as
input parameters for leachate concentrations to the EPACMTP
groundwater model. However, some of the field sampling
procedures that are documented in the NODA reveal that
volatile contaminants, such as benzene, were lost prior to
analysis. For example, Field Sampling Descriptions for R4-
S0-01 (CSO sludge) and R16-US-01 (unleaded gasoline storage
tank sludge) reveal that these waste samples were allowed to
"air dry" prior to collection. Thus, a basic sampling
protocol for wastes containing volatile constituents was
violated. As a result, the CSO sludge sample registered the
lowest concentration of all volatile organics among the four
samples collected by EPA. The unleaded gasoline storage
tank sludge sample also contained ludicrously low
concentrations of volatiles compared to other samples (e.g.,
2.7 ppm benzene compared to 43 ppm and 110 ppm benzene in
the other two samples). As EPA should have realized, the
concentrations of benzene in the air dried samples used as
inputs to the groundwater model were grossly inaccurate. 
(ETC, 00005)

Response: The commenter states that EPA improperly allowed
the samples to be air dried prior to sampling. The
commenter has misunderstood the sampling descriptions in the
Agency's Supplemental Background Document which described
the refineries' practices of air drying the storage tanks
either after draining or water-washing. This procedure was
also described in the 1995 Listing Background Document,
which stated that occupational benzene levels must be
decreased before confined space entry into the tank. This
is typically done to allow for safe entry into the tank by
refinery employees for sludge removal and tank integrity
inspections. Until the air drying process had been
completed, no refinery personnel (or EPA sampling teams)
could enter the tanks without violating standard
occupational safety practices. Current health and safety
regulations specify that prior to entry in a confined space
(e.g., storage tank), the space must be ventilated (e.g.,
air dried) and tested for oxygen levels and the combustible
gases (e.g., benzene) must be below the lower explosive
limit (LEL) and/or chemical of concern (e.g., benzene).

In both cases (i.e., with respect to Samples R4-SO-01 and
R16-US-01), as described in the respective Analytical Data
Reports, refinery personnel shoveled the sludge from the
tanks. The unleaded storage tank sludge was placed in
drums, from which EPA sampled. The CSO sludge was placed on
the refinery's state-permitted "stained soils pad" from
which EPA sampled. In no case did EPA's sampling procedure
allow for additional "air drying." The tank air drying
conducted by the refineries prior to EPA's arrival onsite
for sampling represents standard operating practices
designed to comply with basic occupational safety practices. 
EPA thus concludes that these samples are representative of
residuals generated throughout the industry. 

Note that EPA was limited by scheduling constraints to
collect samples as they were available at the time of EPA's
site visits. The sampling program targeted residuals
generated from a wide range of process units and storage
tanks which generally were operated on independent
schedules. The sampling teams attempted to schedule
sampling trips when the greatest number of samples would be
available. In some cases, facilities had completed
preparation of the residuals for disposal and in others the
residuals were still being removed from the process units. 
Where possible, EPA's priority was to sample the residual
after removal from the units in question to optimize the
value of the sample as a modeling input. This included
after any drying or dewatering conducted by the facility,
based on the assumption that wastes with high liquid content
would not be land disposed.

In some cases, however, the samples were collected directly
from the process unit or tank rather than after scheduled
dewatering or deoiling. These samples were collected prior
to the refineries' residual processing steps either (1) to
avoid cross-contamination with other refinery residuals, or
(2) when the residual processing step was not scheduled at a
time when EPA expected to be able to collect the sample. As
an example, in the case of one of the unleaded gasoline tank
sludges not discussed by the commenter (R8A-US-01), the
facility had not completed residual removal procedures at
the time of the sampling event and the sludge was sampled
directly from the tank bottom. This refinery reported
general use of vacuum trucks to remove tank sludges and
transport them to their sludge de-oiling unit prior to
recycle to the coker or landfilled. Note that the refinery
must have ventilated this tank prior to sampling to allow
for tank entry. The refinery did not want the sample
collected from the truck because of cross-contamination with
other oily residuals. This sample contained higher levels
of volatile and semivolatile organics than the other two
unleaded gasoline tank sludge samples which possibly could
be due to reduced residual handling steps prior to sampling. 
EPA agrees with the commenter that the concentrations in
residuals sampled from the process unit are likely to be
higher than those sampled closer to the point of disposal,
such as the samples referenced by the commenter. The
inclusion of these samples in the data set as inputs to the
groundwater model may be somewhat conservative.

However, in response to the commenter's comparison of
detected benzene levels among the three unleaded gasoline
samples (i.e., 2.7, 43 and 110 ppm), EPA notes that the
Agency's entire sampling data set demonstrates concentration
ranges of multiple orders of magnitude. Table I.C.1
illustrates the range of detected benzene levels within each
of the residual categories. Ranges of at least three orders
of magnitude were observed in total benzene concentrations
for crude oil tank sludge, unleaded gasoline tank sludge,
hydrotreating catalyst, hydrorefining catalyst, reforming
catalyst, and spent caustic. EPA concludes that this
variability is normal and is attributable to many factors in
addition to the place and time of sampling, such as the
various residual generation practices employed among
refineries, differences in process operating conditions,
crude and product slate characteristics, etc. This
variability was anticipated at the outset of this listing
determination and was the basis for EPA's stratified random
selection of refineries for the field study, as well as the
basis for the collection of as many samples as possible (up
to six of each listing residual category) given budget,
availability and schedule constraints. Thus the Agency is
neither surprised nor concerned with the range of benzene
levels detected in the unleaded gasoline storage tank
samples.


Table I.C.1. Range of Total Detected Benzene Concentrations
(ug/kg)


Residual Category: Crude oil tank sediment
Concentration Sample Number
220,000 R8C-CS-01
69,000 R6B-CS-01
52,000 R10-CS-01
8,200 R4B-CS-01
660 J R19-CS-01
<2,500 R22-CS-01


Residual Category: Unleaded gasoline storage tank sediment
Concentration Sample Number
110,000 R8A-US-01
43,000 R6B-US-01
2,700 J R16-US-01


Residual Category: Clarified slurry oil sediment
Concentration Sample Number
1,200 J R9-SO-01
<12,500 R4-SO-01
<12,500 R1B-SO-01
<2,500 R20-SO-01

Residual Category: Hydrotreating catalyst
Concentration Sample Number
500,000 R1-HT-01
160,000 R18-HT-01
24,000 R11-HT-01
9400 J R8A-HT-01
2,900 R22-HT-01
2,000 R3B-HT-01

Residual Category: Hydrorefining catalyst
Concentration Sample Number
100,000 R7B-RC-01
27,000 R21-RC-01
4,200 R5-RC-01

Residual Category: SCOT catalyst
Concentration Sample Number
60 R11-SC-01
<625 R7B-SC-01
<5 R5-SC-01

Residual Category: Reforming catalyst
Concentration Sample Number
26,000 R15-CR-01
2,300 R7B-CR-01
1,000 J R5-CR-01
570 R14-CR-01
430 R11-CR-01
<25 R2-RC-01

Residual Category: Hydrofluoric acid alkylation sludge
Concentration Sample Number
14,000 R8B-HS-01
6,100 J R3-HS-01
<650 R7C-HS-01
<625 R9-HS-01
<313 R15-HS-01

Residual Category: Off-specification product
and fines from thermal processing
Concentration Sample Number
1,500 R11-TP-01
<625 R3B-TP-01
<625 R12-TP-01
<25 R8A-TP-01
<23 R14-TP-01
<5 R6-TP-01

Residual Category: Spent caustic
Concentration Sample Number
2,200 R12-LT-01
420 J R13-LT-01
90 J R3-LT-01
<5,000 R6-LT-01
<500 R3-LT-02
<50 R22B-LT-01

Residual Category: Sludge from H2S removal and
sulfur complex 
Concentration Sample Number
420 J R18-ME-01
96 R5-ME-02
<2,500 R1-ME-01
<1,250 R6-ME-01
<625 R14-ME-01

 Reference: 1995 Listing Background Document.

The commenter correctly states that sample R4-SO-01
generally has lower concentrations of volatile constituents,
and has more constituents reported as "not detected" in
comparison to the other three CSO sediment record samples. 
However, an important fact is omitted by the commenter that
influences the risk analysis. The levels of benzene (the
most important volatile compound from a risk standpoint for
these refinery wastes) across all samples are uniform in
both the total and leachate analyses such that the
calculated average and maximum values are equal for the
total analyses and within 40 percent for the leachate
analyses. Table I.C.2 summarizes the benzene levels in CSO
sediment from page 52 of the October 1995 Listing Background
Document.


 Table I.C.2. Benzene Concentrations in CSO Sediment 


CSO Sediment Record Sample Number
Benzene Concentration, g/kg
TCLP Benzene Concentration, g/L

R4-SO-01
<1,250
<50

R9-SO-01
1,200 (estimated)
84 (estimated)

R1B-SO-01
<1,250
<50

R20-SO-01
<2,500
<50

Average of Four Samples
1,200
59

Maximum of Four Samples
1,200
84


EPA concludes that benzene was not "lost" during the
management of this particular waste at this particular
refinery because benzene levels from other samples
(including samples that were not described by the refineries
as "air-dried") were present at similar levels, in both
total and leachate analyses.

Comment 1.b: As another example, one sample of CSO sludge
was mixed with cement kiln dust prior to sampling, thus the
sample did not reflect the liquid content of the CSO itself. 
Two HF alkylation sludges were "dewatered" prior to
analysis. See Listing Background Document at 135. In
addition, many of the waste sample descriptions reveal that
the sludge samples were composited. The compositing process
can result in substantial loss of volatile compounds, and
the background document does not reveal whether careful
procedures were followed. (ETC, 00005)

Response: In response, EPA notes that it collected samples
of CSO sediment wastes that were available after tank clean
out, and in this specific case, it had been mixed with
cement kiln dust. This was done by the facility prior to
landfilling of the waste. While this treatment may have
altered some properties of this sample, the oil content (16%
TOG) was relatively low, compared to the other three samples
of CSO sediment collected by EPA (see Table 3.1.18 in the
Listing Background Document, 1995). Even if the Agency
discounted entirely the analytical results for the one
sample mixed with cement kiln dust, it would not impact the
risk assessment significantly, because this would only raise
average levels of some critical PAHs slightly (approximately
10-20%). In any case EPA is listing this waste, so
inclusion of this sample had no material impact on EPA's
final decision.

Dewatering, drying, oil recovery, and mixing with cement
kiln dust or diatomaceous earth are all common techniques
used by the refinery industry to prepare residuals for
disposal. These techniques serve a number of valid
purposes, including recovery of valuable hydrocarbons;
reduction of combustible gases to their lower explosive
limit (LEL) as well as benzene concentrations, so that
refinery personnel are not subjected to explosive or
dangerous benzene exposure conditions; waste minimization
goals; and compliance with state restrictions on liquids in
landfills.

EPA researched the frequency that onsite stabilization was
reportedly used by refineries according to the RCRA 3007
survey results (and presents the results here for the first
time). In the survey, the respondents were required to list
all interim management practices, using codes, for each
waste. "Onsite stabilization" was one such code (see page
22 of survey, document number F-95-PRLP-S0023). The survey
mechanism did not provide a method for refineries to
describe their stabilization process. EPA found that 26
refineries reported onsite stabilization (14 percent of the
185 refineries operating in 1992) for treating various
wastes. Of these, 17 treated some type of sludge (i.e.,
crude oil tank sludge, unleaded tank sludge, CSO sludge,
residual oil tank sludge, desalting sludge, or alkylation
sludge) while six treated CSO sludge in particular. Table
I.C.3 summarizes these findings. The survey results do not
identify the stabilization media or the proportions of
waste-to-media; EPA concludes from these data that the
collection of a record sample of kiln dust-stabilized CSO
sludge is representative of management methods used by other
refineries and therefore represents a logical sample
collection and use in the risk assessment. 


Table I.C.3. Use of Onsite Stabilization for Treating
Refinery Wastes in Any Year


Residual Type
# of Refineries
# of Wastes


Crude Oil Tank Sediment
7
7

Unleaded Tank Sludge
3
6

CSO Sludge
6
7

Residual Oil Tank Sludge
6
12

Desalting Sludge
3
5

HF or H2SO4 Alkylation Sludge
2
2

Number of Refineries Represented in Above
17
39

Number of Refineries Conducting Stabilization of Any Listing
or Study Waste
26
67


With respect to the commenter's concern regarding the two
de-watered HF sludge samples, the commenter is referring to
Sample R7C-HS-01, which was sampled after the refinery had
processed the sludge in a centrifuge, and Sample R3-HS-01,
which EPA sampled from the neutralization tank and filtered
in the laboratory at the refinery's request to better
simulate the characteristics of the waste as it would
actually be generated. As discussed in response to the
previous comment, EPA's samples represent the range of
conditions between the process (e.g., in the neutralization
pit) and disposal (e.g., after de-watering). The inclusion
of the samples from the process unit in the modeling data
set may be conservative. The generation of HF sludge is
described further below.

As described in the 1995 Listing Background Document, HF
neutralization sludge is generated when HF acid is
neutralized by aqueous KOH and soluble potassium fluoride
(KF) is produced. Some facilities employ KOH regeneration. 
Periodically some of the KF-containing neutralizing solution
is withdrawn to the KOH regenerator. In this vessel KF
reacts with a lime slurry to produce insoluble calcium
fluoride (CaF2) and thereby regenerates KF to KOH. The
regenerated KOH is then returned to the system, and the
solid CaF2 is routed to the neutralizing tank. The KF, at
facilities that do not have a regenerator, is sent directly
to the neutralizing tank, where it is reacted with lime to
form sludge.

Spent caustic, KOH scrubbers, acidic waters from acid sewers
and, in some cases, CBM (an azeotropic mixture of the HF
acid and water) are charged to neutralization tanks, which
neutralize effluent to the WWTP. Neutralizing controls
fluoride levels to the WWTP. Neutralizing agents (sodium,
calcium, and potassium hydroxide) are selected based on the
refineries' WWTP permits. Effluent to the tank is
neutralized, generally with lime which forms sludge (calcium
fluoride) that collects on the bottom of the pit. This
sludge is the sampled residual of concern. 

As described above, the HF neutralization sludge sampled for
this listing determination is an aqueous-based sludge which
may have small amounts of oil from carryover from the
reactor or the neutralized catalyst. This does not
represent an "oily" sludge but an aqueous sludge which may
contain small amounts of oil. The laboratory personnel
described a strong hydrocarbon odor which was the very
distinct odor of neutralized HF acid or calcium fluoride. 
(Note that R9-HS-01 appears to be an exception with 31% oil
and grease. See response to Comment 7.a for additional
discussion of this sample.)

Field compositing procedures, when necessary, in all cases
were performed for the non-volatile analytes only. 
Compositing consisted of throughly mixing the contents of
all non-volatile grab sample aliquots into a homogeneous
mixture prior to sample containerization. This procedure
was performed for all non-pyrophoric samples regardless of
whether the grab samples were collected from a single source
such as a storage pad or multiple locations such as roll-off
boxes or bins. Conversely, a separate grab sample for
volatiles analysis was collected and maintained in as
undisturbed a state as possible prior to placing the
contents into sample containers without headspace to
minimize volatiles loss. For some samples such as the
catalysts that were potentially pyrophoric, field
compositing procedures were not possible. Instead, these
samples were composited using all the non-volatile sample
contents in the laboratory after they were screened for
pyrophoricity. The volatiles aliquot, as was the case for
all residuals sampled, was maintained in a separate sample
container and was never composited or combined with other
sample aliquots prior to analysis. The laboratory performed
all volatiles analyses using only those containers that were
designated for this analysis by the field sampling
personnel. These sampling and analysis protocols were
consistent with the guidance outlined in Chapter Nine of SW-
846, and were documented in each site-specific Sampling and
Analysis Plan (SAP). Compliance with each SAP was
documented in the site-specific Analytical Data Reports
(ADRs). Thus, careful procedures were followed in sampling
conducted for volatile analyses and loss of volatiles was
minimized.

In conclusion, EPA disagrees with the commenter's assertion
regarding the representativeness of the samples and the
appropriateness of the sample compositing procedures.

Comment 1.c: In addition, in EPA's TCLP analyses the
percentage of benzene captured varies widely, even within a
given waste stream. In comparing benzene capture
efficiencies for different waste streams, it is apparent
that the average benzene capture rate for wastes with high
oil content is significantly lower than for non-oily wastes. 
(ETC, 00005)

Response: The commenter's concern is addressed in response
to Comments 6 and 7 below.

Comment 1.d: Prior to this rulemaking, EPA consistently
acknowledged that the TCLP test substantially underestimates
leachate concentrations of toxic constituents for oily
wastes. See Response to Comments Background Document for
the Listing of Primary and Secondary Oil/Water/Solids
Separation Sludges From the Treatment of Petroleum Refinery
Wastewaters (Aug. 29, 1990). Oily wastes tend to clog the
filter during initial filtration causing inadequate
expression of contaminants and otherwise interfere with the
TCLP test method. See 57 FR 37294 (Aug. 18, 1992);
Evaluation and Modification of Method 1311 for Determining
the Release Potential of Difficult-to-Filter Wastes, Vol. 1,
RTI, April 1990, page 23. (ETC, 00005)

Response: The RTI report referenced by the commenter,
titled "Evaluation and Modification of Method 1311 for
Determining the Release Potential of Difficult-to-Filter
Wastes" dated April 1990, studied the effectiveness of the
TCLP with oily wastes and an alternative filtration
procedure designed to simulate the movement of oily wastes
into soils beneath landfills. The study evaluated four oily
wastes, two of which were obtained from operating petroleum
refineries: slop oil emulsion, and API separator sludge. 
These two residuals are derived from refining wastewater
treatment systems, as are F037/F038 wastes. The
similarities between F037/F038 sludges and API separator
sludge is discussed in detail in the final sludge rulemaking
(55 FR 46376, November 2, 1990).

The petroleum wastes studied by RTI were described as
multiphasic and extremely heterogeneous and difficult-to-
filter. This contrasts with all of the current petroleum
listing residuals except for two HF alkylation samples that
were identified as single phased without free liquid and
considered to be homogeneous wastes (see response to Comment
3.b below for a discussion on the HF samples liquid phase). 
For this reason the RTI report is not considered directly
applicable to the petroleum listing residuals. Note that
the RTI report concluded that the TCLP method was adequate
for filterable "oily" wastes, such as the samples of API
separator sludge tested (see pages 79 and 155 of RTI's
report). This issue is explored further in Section III.H of
the Proposal RTC.

Comment 2: Improper Consideration of Air Dried Samples

The NODA materials include field sampling descriptions for
some of the wastes covered by this rulemaking. In at least
two instances, the samples were taken of wastes that were
allowed to "air dry" prior to collection. Therefore, the
volatile contaminants in these wastes were allowed to escape
prior to sample collection, in violation of basic sampling
protocols for handling wastes containing volatile chemicals.

The effect of this air drying is clear and profound, upon
comparing the analytical results of these samples to the
other waste samples. The CSO sludge sample registered the
lowest concentration of all volatile organics among the four
samples collected by the Agency. The concentrations of
total xylenes and naphthalene in this sample are more than
an order of magnitude lower than the maximum concentration
detected in the other three samples.

The unleaded gasoline storage tank sludge sample was one of
three waste samples collected by the Agency. This sludge
sample contains 2.7 ppm benzene, as compared to 43 ppm and
110 ppm benzene found in the other two samples. 
Therefore, for the principal constituent of concern in EPA's
groundwater modeling, the volatile contaminant concentration
in the air dried sample is 6.2% and 2.4% of the comparable
benzene concentration in the two other samples.

Given the substandard field sampling procedure utilized and
its resulting analytical impacts, these air dried samples
must be discarded. Once the air dried unleaded gasoline
tank sludge sample is discarded, the mean benzene waste
concentration for this waste rises from 51.9 ppm to 76.5
ppm, significantly altering the modeling results for this
waste. Where KGS adjusted only the TCLP value to reflect
EPA's purported 53% benzene leaching efficiency (as
discussed above) of the revised mean value, the TCLP value
increases from 0.75 mg/l to 2.03 mg/l, and the resulting
groundwater pathway risk increases by more than half. More
importantly, when the modification is considered in
conjunction with parameter revisions, the resulting risk
estimates are substantially modified, as discussed
immediately below. (EDF, 00006, pg 41)

Response: See responses to Comment 1, above. EPA
fundamentally disagrees with the commenter that Samples R4-
SO-01 and R16-US-01 should be removed from the Agency's
modeling input data set and with the commenter's contention
that EPA's sampling procedures were "substandard".

Comment 3: Field and Laboratory Observations of
Wastes

Comment 3.a: EPA states that the petroleum refinery wastes
are not "oily." In making this statement the Agency's 
point of reference is used oil which is "essentially all
oil." However, a waste does not have to be "essentially all
oil" in order to be subject to the OWEP test. A review of
the "Scope and Applicability" section of Method 1330A of
SW846 (the OWEP) shows that this method is applicable to
materials that are not "essentially all oil" including
sludges, emulsions, rags, and "other oil wastes derived from
petroleum refining." The OWEP is not intended to be applied
only to samples that contain "all oil" but to any sample
with significant amounts of oil that would preclude use of
merely the aqueous-based TCLP test extraction medium. (ETC,
00005)

Response: The commenter has taken EPA's statement out of
context. In Section 2.1 of the Supplemental Listing
Background Document (March 1997), EPA introduced its
description of "Field Laboratory Observations of Wastes"
with the following:

 "Commenters suggested that the wastes evaluated in the
 proposed listing determination are oily in nature and
 have high levels of "free" oil. EPA contends that the
 residuals are not oily in the manner anticipated by the
 commenter." (Emphasis added)

EPA has not disputed that the residuals of concern contain
oil, but that they contain free oil which could move in the
environment as a separate phase or pose the types of TCLP
filtration problems described in RTI's 1990 study.

As described in SW-846, Third Edition, the OWEP was designed
to address the mobility of metals from oily matrices. The
commenter is implying that it is an alternative to the TCLP
for oily wastes; this is not accurate. OWEP was developed
in 1986 for the Delisting Program and modified in 1992, as
an alternative to the EP Toxicity Test Method, to address
concerns regarding the EP's ability to measure metals
mobility in oily matrices. The method was actually designed
to liberate through a traditional leaching protocol, the
metals present in the solid phase after solvent removal of
the oily-organic phase and thereby predict the metals
leachability from waste streams in which the organic phase
could potentially inhibit the metals mobility (see response
to Comment 5.a below for additional details). More
specifically, the OWEP method was developed for samples with
a distinct solid phase and liquid component consisting of
oil. The OWEP method differs from both the EP and TCLP
methods in that the solid phase is first extracted with
tetrahydrofuran and then toluene to remove the oily organic
layer prior to the solids leaching procedure. Therefore,
this leaching method is only applicable to the inorganic
metals constituents since any organic constituents
originally present in the solid phase would be removed with
the solvent extraction. 

Comment 3.b: EPA then goes on to state that "[c]rude oil
tank sediment, the oiliest of all the residuals of concern,
was never observed by the Agency during the sampling and
analysis to exhibit an oily phase" (emphasis added). A 
review of Tables 1 and 2 of the Listing Support Document
quickly contradicts EPA's assertion. Table 1 contains
descriptions of the samples of Crude Oil Tank Sediments. 
Descriptions such as "oily black appearance" and "black and
oily" are seen for several of the samples. Table 2 shows
the analysis results for percent oil and grease performed on
samples of Crude Oil Tank Sediments. The results averaged
20.7% oil and grease with results as high as 41%. This is a
substantial oily phase, and the data contradicts EPA's
statement quoted above from the text of the Listing Support
Document. (ETC, 00005)

Response: While the sampled residuals obviously contain oil,
this observation is not equivalent with concluding, as the
commenter does, that a discrete "substantial oily phase" is
present in these residuals. During EPA's observation and
handling of crude oil tank sediment during sampling and
laboratory analysis, a discrete oily phase was not observed. 
This held true even for Sample R8C-CS-01 which was collected
by refinery personnel directly from the bottom of the
drained crude oil storage tank. This sampling approach for
R8C-CS-01 deviated from the anticipated procedures as
specified in the Sampling and Analysis Plan in which the
sample was expected to be collected from roll-off boxes
after the tank bottoms had been centrifuged. The refinery
requested this modification in the planned sampling
procedure because the refinery was concerned that the
samples would be contaminated by other materials processed
in the refinery's de-oiling unit. Since this refinery de-
oils their tank sludge prior to landfilling it, the Agency
agreed to remove any free liquid phase prior to analysis. 
The laboratory was instructed to filter this sample prior to
any total or TCLP analyses, however, the laboratory reported
there was no free liquid present in any of the sample
container aliquots and that pressurized filtration as
specified for the TCLP did not produce a liquid phase. 

Similarly, a discrete oil phase was not observed for Sample
R10-CS-01, which was sampled directly after removal from the
storage tank. No separate oil phase was observed by the
samplers or the analytical laboratory despite the facility's
intention to recycle this residual to the refinery's
cracking unit and to add additional liquid hydrocarbon to
the sludge to make it more pumpable to the refining
process. If the refinery had instead intended to landfill
this sludge, it likely would have been a good candidate for
hydrocarbon recovery via deoiling given its high oil and
grease content (41 percent) and to ensure that it passed the
paint filter test. 

While collecting Sample R19-CS-01, the sampling team
observed a "small amount of water present" in the storage
bin. The field log stated that "the weather at the site was
cloudy and damp, rain having fallen steadily overnight,"
accounting for the sampling team's observation of water in
the storage bin. A water phase was not present in the
sample or observed by the laboratory personnel. As stated
in the Supplemental Background Document, "crude oil tank
sediment, the "oiliest" of all the residuals of concern, was
never observed by the Agency during sampling and analysis to
exhibit an oil phase." 

An integral step in the TCLP is filtration when multiple
phases are anticipated. The contract laboratory determined
through sample screening and preparation that filtration was
unnecessary for all residuals listed in Table 1 of the 1997
Supplemental Listing Background Document except for two HF
alkylation samples R8B-HS-01 and R9-HS-01. These samples
were filtered and found to contain 50% and 24% liquid,
respectively. In both cases the filtrate was compatible
with the leachate and was combined for the semivolatiles and
metals analyses. Volatiles analyses were performed
separately on the filtrate and leachate portions with the
detected target analyte concentrations combined
mathematically based on the ratio of filtrate and leachate
to total volume. It is also important to note that the %
oil and grease for sample R9 was 31% and was the third
highest level reported for samples listed in Table 1,
however, there were no reported difficulties encountered
during the filtration procedure. The Agency also notes that
among all of the samples analyzed via the TCLP in its
petroleum refining investigation, none of the samples for
which filtration was required generated a phase that was
immiscible with the TCLP leachate. In other words all
generated filtrates were soluble with the TCLP extraction
fluid according to Section 7.2.13.2 from Method 1311; these
filtrates did not represent separate oil phases.

It is possible to conclude based on a superficial reading of
the 1990 RTI report that no separate phase was generated
from these residuals because of the shortcomings in the TCLP
filtration step identified in the RTI report. However, a
closer examination of this study shows that the samples of
concern to EPA in the current petroleum refining
investigation differ dramatically from the samples studied
in the RTI report titled "Evaluation and Modification of
Method 1311 for Determining the Release Potential of
Difficult-to-Filter Wastes" dated April 1990, which were
fluid in nature and obviously contained multiple phases. 
Further, RTI documented that one of the two refinery wastes,
API separator sludge, in fact did not pose a filtration
problem and thus was only studied during the first phase of
RTI's study.

Comment 3.c: Another key point is the tarry consistency of
several of the waste samples. Tar is a petroleum based
material consisting of higher molecular weight fractions of
petroleum products. Although these fractions are solid at
room temperature, they still constitute an immiscible oily
phase when subject to the TCLP test. An OWEP is more
effective at extracting metals from this phase then a TCLP
extraction medium. Tarry waste is derived from petroleum
refining and does constitute an oily type material that is
subject to the OWEP test, per the applicability section of
Method 1330A. (ETC, 00005)

Response: In response to comments on the 11/20/95 proposal,
EPA did conduct the OWEP. EPA does not believe, however,
that the results of these analyses are appropriate for use
as input to the groundwater model (see response to Comment 5
below).

Comment 4: Reported Oil and Grease Levels of Wastes Sent to
Landfills

EPA attempts to make the argument that the petroleum
refinery wastes that currently are disposed of in landfills
are low in oil content. However, EPA concludes its NODA
discussion with a statement that the average oil content of
a significant subset of these wastes is 19%, after
eliminating outlier data points. This represents a
significant volume of waste with a substantial oil phase. 
When considering the hundreds of thousands of tons of these
petroleum refinery wastes, 19% of this tonnage represents a
substantial amount of waste with essentially an all oil
phase. This fraction needs to be adequately characterized
using the OWEP, since it represents a major amount of oily
waste phase that is highly mobile in a land disposal
scenario. (ETC, 00005)

Response: EPA reiterates that the March 1997 Supplemental
Listing Background Document, and more specific data supplied
to EDF through a FOIA, incorporates a great deal of
information concerning oil and grease data of refinery
wastes. The commenter has incorrectly construed EPA's
evaluation of the oil and grease data. Specifically, EPA
evaluated the available data to conclude that the median oil
and grease content of landfilled residuals is less than 1
percent (see Appendix A to the Supplemental Listing
Background Document). EPA did find a limited number of
cases where the oil and grease content was greater than 10
percent. The commenter refers to text which is in reference
to residuals that were landfilled off-site. EPA
specifically verified the data for these residuals and
determined that the average oil and grease content of these
six wastes is 19 percent. This "subset" referred to by the
commenter cannot appropriately be assumed to be
representative of all such residuals landfilled offsite; it
merely shows that the average oil and grease values of the
six most oily waste is a certain value. EPA never implied
that these particular samples with oil and grease levels
above 10 percent are representative of other wastes, as
stated by the commenter, and disagrees with the commenter's
interpretation of these data.

EPA points out that the Agency's percent oil and grease
results presented in the NODA were obtained using Method
9071A. This method involves extracting a chemically dried
waste sample with a strong organic solvent,
trichlorotrifluoroethane (Freon-113), in order to solubilize
the heavy petroleum fraction constituents associated with
oil and the nonvolatile greases. While EPA measured levels
of "total oil and grease" (TOG) that appeared high for some
wastes (e.g., up to 25 percent for crude oil storage tank
sediment), the Agency stresses that the TOG method used
measures all extractable organic material, including waxes,
greases, and other large molecular weight substances. The
TOG method does not measure, in any sense, "free" oil (i.e.,
oil that might migrate from the waste as a separate phase). 
This procedure will also recover any organic materials
soluble in trichlorotrifluoroethane that are not volatilized
during the solvent extract evaporation step. Thus, Method
9071A oil and grease results will likely overestimate free
flowing oil content and wastes with apparently high oil and
grease concentrations may not contain mobile oil.

Further, as described above, there is an important
distinction between oil content, percent oil and grease, and
a discrete oil phase. EPA believes that refineries have a
number of important incentives to minimize the potential for
free oil phase development in wastes destined for land
disposal, including state restrictions on liquids in
landfills, waste minimization practices, and recovery of
valuable feedstock. Furthermore, percent oil and grease
results encompass many materials other than free oil since
all nonvolatile compounds soluble in
trichlorotrifluoroethane are potentially recovered and
quantitated. EPA thus fundamentally disagrees with the
commenter that these data point toward the conclusion that
these residuals commonly exhibit "essentially an all oil
phase," or that the OWEP is the appropriate leaching model.

Comment 5: Alternative Leaching Methods

Comment 5.a: EPA argues that the OWEP is not appropriate,
and then discusses the results of re-analysis of 27 samples
using the OWEP and testing the extraction medium for metals. 
EPA concludes that the oil content of the relevant wastes
does not affect the metals mobility. 

First, the ETC does not agree with EPA's remark that the
OWEP would "over estimate" the leaching potential of metals
from the waste. The point of using the OWEP test is to
properly and accurately account for metals tied up in the
oily phase that would be mobile in a land disposal scenario. 
Failure to use the OWEP results in erroneous under-
estimation of the true mobile metals content of the waste
stream. EPA then states that use of the OWEP "may cause
drastic changes in the original sample matrix." This is
also a misleading statement. The OWEP is the test applied
to the original un-altered waste matrix. It does not change
the waste matrix, just as the TCLP test does not change the
waste matrix. In conclusion, both of EPA's qualitative
arguments against use of the OWEP are totally wrong,
misleading, and invalid defenses against EPA's failure to
use the proper extraction procedures to characterize oily
waste. (ETC, 00005)

Response: The commenter correctly quotes page 10 of the
March 1997 Listing Support Analysis for Petroleum Refining
Wastes. The commenter, however, is incorrect in stating
that the purpose of the OWEP method is to "properly and
accurately account for metals tied up in the oily phase". 
The method was actually designed to liberate (through a
traditional leaching protocol) the metals present in the
solid phase after solvent removal of the oily-organic phase. 
Although the solvent and leachate phases are analyzed
separately with the results combined mathematically to
obtain the OWEP result, the metals concentrations in the
solvent phase in some cases are greater than the leachate
values due to the smaller volume of solvent (0.6 L) compared
to the leachate volume (1.3 L). However, the metals solvent
concentration contributes very little to the final OWEP
result since the concentration in (mg) associated with 0.6 L
is diluted by a combined total volume of 1.9 L (see response
to Comment 7.g for the equation for calculating the final
leachate concentration that is also provided in Method
1330).

One disadvantage of the OWEP is that it changes or alters
the original sample matrix to render it unusable for the
determination of the leaching potential for the organic
constituents. Any organics present prior to the solvent
extraction step will likely be removed after Soxhlet
extraction similar to the total analysis procedures for
volatiles and semivolatiles using methanol and methylene
chloride. Leaching the solvent extracted solid phase for
organic target analytes would result in the inaccurate and
falsely low determination of leachate constituents while
the analysis of the solvent phase would more closely
resemble the total concentration. 

Further, EPA continues to maintain that the initial
extraction with organic solvents in the OWEP may well
drastically alter the waste matrix. The aqueous extraction
that follows the initial organic extraction will see a very
different waste matrix from that in the original sample,
i.e., most organic material (as well as oil) is removed. 
While the test was designed to do this, the Agency
recognizes that this approach may not be fully
representative of possible leaching from a landfill. 

Comment 5.b: Secondly, EPA's re-analysis of the samples
using the OWEP is not an accurate indication of the degree
of underestimation of the leaching potential of these wastes
for metals. The TCLP tests performed on the samples were
conducted in 1993. EPA merely retrieved these aged samples
from storage, and ran the OWEP analysis on these archived
samples. Three years separate the TCLP analysis and the
OWEP analysis. Holding times of metals have been exceeded,
and therefore the results are not valid to draw definitive
conclusion. (ETC, 00005)

Response: EPA agrees that the OWEP analysis was conducted
outside of the optimal holding times for these samples. As
such, EPA believes that the exact measurements should not be
relied on for risk assessment evaluations. However, EPA
undertook the OWEP analysis in an attempt to fully consider
the commenter's concerns. The purpose of adhering to the
method-specified holding times of 180 days to leaching and
an additional 180 days for analysis is to minimize the loss
of potential contaminants through volatilization or
biodegradation. The primary concern with exceeding holding
times is that the sample matrix would degrade, changing
leaching properties and that volatilization would reduce
contaminant levels. However, given the archiving practices
of the laboratory in which samples were stored in their
original sealed containers at room temperature (note that
the unrefrigerated storage of samples designated for metals
analysis is considered an acceptable practice) without
exposure to light. Under these conditions any potential
sample decomposition was minimal and with the seven
constituents of concern, non-volatile metals, EPA believes
that the results are of some use for comparative purposes in
response to the commenters' concerns. 

Comment 5.c: A review of Tables 1 through 7 of Appendix B
of the report reveals further problems. The metals
detection limits used for the 1993 TCLP analysis are higher
than the reported detection levels for the 1996 OWEP
analysis, making the two data sets impossible to compare. 
The 1993 TCLP analysis could have been performed to the same
lower detection levels as the 1996 OWEP analyses; the
laboratory simply did not choose to analyze to a lower
level. Samples for which non-detect levels were reported in
1993 cannot be compared with the OWEP analysis performed in
1996. (ETC, 00005)

Response: EPA agrees that the differences in the TCLP and
OWEP detection levels limits the extent of subsequent
comparisons, however, insufficient sample leachate volumes
were available for the re-analysis of the TCLP. Given the
time constraints of the rulemaking schedule and the
significant logistical constraints associated with sampling
many of these residuals, it was not possible to collect
additional sample volumes.

The 1993 TCLP analyses referred to by the commenter were
predominantly performed in mid to late 1994. These TCLP
metals samples were leached according to SW-846, Method
1311, and the resulting leachate acid digested according to
Method 3010A. The TCLP digestates were then analyzed for
the same target analytes as the total metals constituent
list with the exception of sodium. The determinative
methodology included CVAA, Method 7470A for mercury; GFAA,
Methods 7060A, 7421, 7740, and 7841 for arsenic, lead,
selenium, and thallium, respectively; and ICP, Method 6010A
for all other analytes.

Prior to digestion, all leachates for both the original TCLP
and the OWEP determinations were diluted by a factor of ten
to minimize the effect of the acetate buffer leaching
solution on the target analyte quantitation. The analytical
detection limits for the OWEP leachates are approximately
five times below those reported for the TCLP leachates due
to the increased sensitivity obtained with the OWEP
analytical technique (ICP-MS) compared to the TCLP analyses
using ICP and GFAA. In addition, the OWEP solvent detection
limits were substantially less than the TCLP detection
limits since these extracts were digested directly without
dilution. 

Comment 5.d: Samples with detected levels in 1993 for the
TCLP, when compared to the 1996 OWEP analyses, show
substantial differences in leachable metals. For example,
measured mobility of arsenic is as much as 5 times higher,
and chromium and lead are 10 times higher. This dramatic
difference between the TCLP and OWEP metals results does
support the concern that the oil content of the waste
significantly impacts the mobility of metals in the wastes. 
(ETC, 00005)

Response: In evaluating the arsenic OWEP/TCLP data, the
only residual where OWEP appears to consistently demonstrate
higher leaching levels is for hydrotreating catalysts. For
two samples, OWEP results are two to three times higher than
the detection limits reported for the TCLP results. For two
other samples, OWEP results are an order of magnitude lower
than the TCLP detection limits. For the fifth sample, OWEP
results are 4.4 times greater than TCLP results. These
results, however, do not support the commenter's claim that
leaching behavior of oily wastes is better measure with the
OWEP because none of the hydrotreating catalysts samples had
detectable levels of oil and grease. Thus, the OWEP results
for these samples could be considered irrelevant as far as
evaluating the impact of oil and grease content on metal
leachate. 

Furthermore, as discussed earlier, there is greater
variability within each waste category (e.g., hydrotreating
OWEP results range from 0.02 to 6.69 mg/l arsenic as
documented in Appendix B of Supplemental Background Document
Listing Support Analysis, 1997) than between the OWEP and
TCLP results. EPA disagrees that any measurable
differences, of which there are few, in OWEP/TCLP results
are dramatic or particularly meaningful. In addition, EPA
does not give the OWEP results the same weight of validity
as the TCLP results because the samples were old and
subjected to aggressive pre-leaching with organic solvents. 
Moreover, the OWEP results for arsenic in hydrotreating
catalysts suggest that the aggressive organic leaching in
the OWEP procedure may be disturbing the waste matrix
sufficiently to cause some increase in mobility (without oil
content being a concern). However, the data are too limited
to draw any conclusions.

The following table reduces the results of the OWEP analyses
to the most relevant results: those samples with oil and
grease content greater than 1 percent, as well as detected
results for either OWEP or TCLP analyses.


 Table I.C.4. OWEP / Original TCLP Data Comparison


Residual
Sample ID
%Oil & Grease
OWEP
TCLP
 
 
 Arsenic mg/L
Crude Sludge
R8C-CS-01
25
0.03
<0.10

CSO Sludge
R9-SO-01
70
0.11
<0.10
 
CSO Sludge
R20-SO-01
24
0.04
<0.10

 Barium mg/L

Crude Sludge
R8C-CS-01
25
3.33
2.4

Crude Sludge
R4B-CS-01
15
0.22
< 2

Crude Sludge
R10-CS-01
41
0.88
< 2

Crude Sludge
R22-CS-01
4.9
0.38
< 2

Crude Sludge
R19-CS-01
14
0.64
2.7

CSO Sludge
R9-SO-01
70
0.33
< 2 

CSO Sludge
R1B-SO-01
16
0.70
< 2

CSO Sludge
R20-SO-01
24
0.39
< 2

HF Alkylation Sludge
R9-HS-01
31
0.29
< 2

HF Alkylation Sludge
R15-HS-01
6.8
0.08
< 2

Sulfur Complex Sludge
R1-ME-01
1.0
0.11
< 2

Off-Spec Product
R12-TP-01
8.4
0.64
< 2

 Chromium, mg/L

Crude Sludge
R8C-CS-01
25
0.89
< 0.10

Crude Sludge
R4B-CS-01
15
0.02
< 0.10

Crude Sludge

R10-CS-01
41
0.01
< 0.10

Crude Sludge
R22-CS-01
4.9
0.01
< 0.10

Crude Sludge
R19-CS-01
14
0.06
< 0.10

CSO Sludge
R9-SO-01
70
0.01
< 0.10

CSO Sludge
R1B-SO-01
16
0.04
< 0.10

CSO Sludge
R20-SO-01
24
0.03
< 0.10

HF Alkylation Sludge
R9-HS-01
31
0.02
< 0.10

HF Alkylation Sludge
R15-HS-01
6.8
0.06
< 0.10

Sulfur Complex Sludge
R1-ME-01
1.0
0.02
< 0.10


Off-Spec Product
R12-TP-01
8.4
0.01
< 0.10

 Lead, mg/L

Crude Sludge
R4B-CS-01
15
0.07
< 0.03

Crude Sludge
R10-CS-01
41
0.03
< 0.03

Crude Sludge
R22-CS-01
4.9
0.01
< 0.03

Crude Sludge
R19-CS-01
14
0.30
<0.03

CSO Sludge
R9-SO-01
70
0.01
 < 0.03

CSO Sludge
R1B-SO-01
16
0.01
< 0.03

HF Alkylation Sludge
R9-HS-01
31
0.00
< 0.03

 Selenium, mg/L

Sulfur Complex Sludge
R1-ME-01
1.0
0.11
< 0.05

Shaded rows in Table I.C.4 represent samples with both OWEP
and TCLP detected values, of which there are only two. 
These two barium results in crude oil tank sediment samples
are within one order of magnitude, and show no pattern as
one pair has higher OWEP results while the other has higher
TCLP results. 

Bolded OWEP results in Table I.C.4 indicate samples where
OWEP leaching is greater than TCLP (using TCLP detection
limits). Only six of the 35 data pairs show this pattern. 
(It is not possible to determine whether the OWEP or TCLP
indicated greater leaching for the remainder of the relevant
samples because of the TCLP detection limits.) EPA does not
believe that these results demonstrate any dramatic
differences in leaching.

Comment 5.e: A fundamental problem with the report is that
three years separate the OWEP and TCLP analyses, and holding
times of metals have been greatly exceeded. These results
are invalid and violate EPA's own QA/QC requirements. 
Furthermore, the difference in levels of detection used by
the laboratories in 1993 compared to 1996 makes most of the
data useless. Finally, nowhere is the total metals content
of the waste reported. Assessment of leachability of metals
must be made relative to the total metals composition of the
waste. The comparison between the TCLP and OWEP methods on
the waste samples does not show the initial total metals
content of the samples before the extraction procedures. 
Since the objective is to compare the two extraction
procedures with regard to impact of the oil phase on metals
mobility, the initial metals content is a critical point
that must be known. To properly demonstrate this point, EPA
needs to obtain new samples of the various waste streams,
and run concurrent total, TCLP and OWEP metals analyses. 
(ETC, 00005)

Response: EPA agrees that the holding times were exceeded,
but as discussed above, believes that the results are useful
in exploring the commenter's concerns. EPA realized that
the data are only of limited utility due to the problems
noted. However, despite these limitations, EPA believes that
the data support the overall conclusion that the oily
content of the waste has no significant effect on the
leachability of the metals. Thus, EPA disagrees that it is
necessary to conduct further sampling and analysis. 

Note that total metals levels were reported with TCLP
results in the 1995 Listing Background Document and are not
expected to change between the times of the TCLP and OWEP
analyses.

Comment 5.f: The report, as it stands now, does not support
EPA's assertion that failure to use the OWEP would not have
affected the listing determination with regard to mobility
of metals. If anything, the handful of useful data points,
for which detection levels were obtained on TCLP in 1993,
show substantially higher mobility of metals under the OWEP
for arsenic, lead and chromium. The data further supports
the concerns raised by commenters that the oily phase of the
waste does significantly impact the mobility of arsenic,
chromium and lead. (ETC, 00005)

Response: See responses above to Comment 5.a through 5.e.

Comment 6: Analysis of Leaching Efficiency

Comment 6.a: EPA evaluated the efficacy of the TCLP for
organic constituents for waste samples relevant to the
listing determination. Only one organic constituent,
benzene, was evaluated. EPA presented the results of TCLP
analysis for benzene on the various samples and calculated
the percent of benzene extracted by comparing this to the
total benzene content of the waste. EPA concluded that the
TCLP test adequately predicts the mobility of organic
hazardous constituents, and is not adversely impacted by the
oil content of the waste.

This conclusion is absurd in that EPA did not bother to
analyze the benzene leachability using the OWEP. There is
no side-by-side comparison of percent benzene extracted for
the TCLP vs. the OWEP procedures. The OWEP procedure would
likely have leached a higher percentage of benzene, and
would be expected to more accurately predict the mobility of
organic hazardous constituents in an oily waste matrix. EPA
simply chose not to run the OWEP analyses. EPA's conclusion
is based on a subjective and biased opinion that the TCLP
extractions give a high enough percentage of benzene
extracted. For example, for the crude tank sludge sample
number R10-CS-01 in Table 2, 22% of the benzene is leached
using the TCLP for a sample with 41% oil phase. It is
highly likely that the OWEP would yield a significantly
higher percentage of benzene mobility. EPA cannot conclude
that the TCLP procedure is sufficient for organic
constituents without also running the OWEP. (ETC, 00005)

Response: As stated previously (see response to Comment
5.a), the commenter has a fundamentally flawed understanding
of the OWEP method. The OWEP was designed to measure metals
mobility in oily matrices, as an aggressive alternative
method to the EP. Currently, EPA does not have a comparable
method for the TCLP since the OWEP method would inaccurately
determine leachable organic constituents that would more
closely resemble the total sample concentration. Moreover,
toluene used as an OWEP solvent is also a volatiles target
analyte and would interfere in the low level detection of
other volatile constituents. For this reason, EPA limited
its OWEP analyses to metals. 
 
Comment 6.b: Finally, a key flaw in EPA's conclusions
regarding organic constituents is that EPA only ran one
constituent, benzene. Other organic hazardous constituents
found in significant concentrations in these petroleum
refining wastes should have also been evaluated. 
Constituents with different polarities and solubility
properties, such as halogenated organics, phenolics and
polynuclear aromatic compounds should have been evaluated. 
The report proves nothing regarding the mobility of
hazardous organic constituents under the TCLP test compared
to the OWEP procedure, and the impact of the oily nature of
the waste on this mobility. (ETC, 00005)

Response: The leaching potential of benzene was evaluated
because this compound was consistently detected in all
samples listed in Table 2 of the 1997 Supplemental Listing
Background Document. Furthermore, due to its high toxicity
and relative mobility, benzene was a key constituent in the
risk analysis results. Based on the commenter's concern for
the lack of reviewing a full range of organic constituents,
the Agency further evaluated the leaching potential of four
additional target analytes (m,p-xylenes, naphthalene, 3/4-
methyl phenol, and phenanthrene). These leaching potential
data are presented in Tables I.C.4 through I.C.7 below. A
review of these data indicates there is no significant
discernable trend with respect to lower leaching values
associated with higher oil and grease content. The
constituents generally leached in similar proportions for
all residual types and any differences may be attributed to
sample homogeneity, pH, particle size distribution and other
factors that have some impact on the leaching rate and the
final leachate target analyte concentration. In addition,
even though phenanthrene and several other PAH compounds
were detected at significant levels in the total analyses,
the concentrations are expected to be low in the leachates
due to the relative insolubility of these compounds in
water.
 


Table I.C.4. PETROLEUM REFINING RESIDUALS LEACHING
POTENTIAL


Sample ID
Total m,p-Xylenes (g/kg)
TCLP m,p-Xylenes(g/L)
% m,p-Xylenes Leached1
% Oil & Grease

 CRUDE TANK SLUDGE

R6B-CS-01
320,000
1,500
9
24

R8C-CS-01
830,000
1,300
3
25

R4B-CS-01
180,000
450
5
15

R10-CS-01
390,000
560
3
41

R19-CS-01
1,400
< 50
<70
14

R22-CS-01
18,000
120
13
4.9

 UNLEADED GASOLINE TANK SLUDGE

R6B-US-01
1,400,000
3,200
5
NA

R8A-US-01
1,300,000
6,100
9
0.09

R16-US-01
610,000
2,700
9
< 0.09

 CSO SLUDGE

R4-SO-01
11,000
250
45
NA

R9-SO-01
19,000
100
11
70

R1B-SO-01
69,000
250
7
16

R20-SO-01
100,000
160
3
24

 HYDROTREATING CATALYST 

R1-TC-01
550,000
13,000
47
< 0.05

R8A-TC-01
280,000
520
4
NA

R11-TC-01
34,000
150
10
< 0.05

R3B-TC-01
30,000
130
9
< 0.05

R18-TC-01
12,000
46
8
< 0.05

R22-TC-01
99,000
3,000
61
< 0.2

 HYDROREFINING CATALYST 

R5-TC-01
4,100
< 50
<24
NA

R7B-RC-01
78,000
530
14
NA

R21-RC-01
23,000
< 50
<4
0.08

 REFORMING CATALYST 

R2-CR-01
220
< 50
NA
NA

R5-CR-01
170,000
1,500
18
NA

R7B-CR-01
9,000
340
76
NA

R11-CR-01
< 25
500
NA
NA

R14-CR-01
4,500
140
62
NA

R15-CR-01
69,000
NA
NA
NA

 HF ALKYLATION SLUDGE 


R3-HS-01
352,000
480
3
NA

R8B-HS-01
< 625
< 50
NA
0.3

R9-HS-01
3,700
< 50
<27
31

R15-HS-01
460
< 50
NA
6.8

R7C-HS-01
1,200
< 50
<83
0.08

 SULFUR COMPLEX SLUDGE 

R1-ME-01
54,000
630
23
1.0

R5-ME-01
480
< 50
NA
NA

R6-ME-01
1,000
340
100
NA

R14-ME-01
790
< 50
NA
0.2

R18-ME-01
< 600
< 50
NA
< 0.05

1 Percent m,p-xylenes leached calculated based on a 20 to
1 ratio of leaching fluid to sample mass. The total
concentration was multiplied by 0.05 to obtain the total
theoretical leachate concentration. This value was divided into
the reported TCLP concentration to obtain the percent leached. 
Calculated percentages greater than 100% are listed as 100%
leached.

Table I.C.5. PETROLEUM REFINING RESIDUALS LEACHING POTENTIAL 
 
Sample ID
Total Naphthalene (g/kg)
TCLP Naphthalene(g/L)
% Naphthalene Leached1
% Oil & Grease
 
 CRUDE TANK SLUDGE

R6B-CS-01
180,000
65
1
24

R8C-CS-01
150,000
77
1
25

R4B-CS-01
280,000
500
4
15

R10-CS-01
150,000
59
1
41

R19-CS-01
< 11,500
< 50
NA
14

R22-CS-01
6,100
14
5
4.9

 UNLEADED GASOLINE TANK SLUDGE

R6B-US-01
190,000
780
8
NA

R8A-US-01
400,000
830
4
0.09

R16-US-01
49,000
640
26
< 0.09

 CSO SLUDGE

R4-SO-01
62,000
32
1
NA

R9-SO-01
88,000
23
1
70

R1B-SO-01
180,000
170
2
16

R20-SO-01
360,000
< 50
<1
24

 HYDROTREATING CATALYST 

R1-TC-01
1,000
< 50
NA
< 0.05

R8A-TC-01
250,000
170
1
NA

R11-TC-01
< 165
< 50
NA
< 0.05

R3B-TC-01
1,100
< 50
NA
< 0.05

R18-TC-01
400
< 50
NA
< 0.05

R22-TC-01
140
< 50
NA
< 0.2

 HYDROREFINING CATALYST 

R5-TC-01
< 165
< 50
NA
NA

R7B-RC-01
3,000
< 50
NA
NA

R21-RC-01
580
170
100
0.08

 REFORMING CATALYST 

R2-CR-01
2,100
59
56
NA

R5-CR-01
8,900
27
6
NA

R7B-CR-01
190
< 50
NA
NA

R11-CR-01
130
< 50
NA
NA

R14-CR-01
< 165
< 50
NA
NA

R15-CR-01
6,900
< 50
<14
NA

 HF ALKYLATION SLUDGE 

R3-HS-01
110,000
320
6
NA

R8B-HS-01
< 1,000
< 50
NA
0.3

R9-HS-01
4,800
< 50
<21
31

R15-HS-01
< 2,063
< 50
NA
6.8

R7C-HS-01
2,000
22
22
0.08

 SULFUR COMPLEX SLUDGE

R1-ME-01
13,000
93
14
1.0

R5-ME-01
18,000
42
5
NA

R6-ME-01
< 16,500
< 50
NA
NA

R14-ME-01
< 2,063
< 50
NA
0.2

R18-ME-01
< 165
< 50
NA
< 0.05


1 Percent naphthalene leached calculated based on a 20 to
1 ratio of leaching fluid to sample mass. The total
concentration was multiplied by 0.05 to obtain the total
theoretical leachate concentration. This value was divided into
the reported TCLP concentration to obtain the percent leached. 
Calculated percentages greater than 100% are listed as 100%
leached.

Table I.C.6. PETROLEUM REFINING RESIDUALS LEACHING
POTENTIAL 


Sample ID
Total 3/4-Methylphenol (g/kg)
TCLP 3/4-Methylphenol g/L)
% 3/4-Methylphenol Leached1
% Oil & Grease
 
 
 CRUDE TANK SLUDGE

R6B-CS-01
< 10,313
< 50
NA
24

R8C-CS-01
< 4,125
< 50
NA
25

R4B-CS-01
12,000
490
82
15

R10-CS-01
< 49,500
< 50
NA
41

R19-CS-01
< 11,500
< 50
NA
14

R22-CS-01
< 413
< 50
NA
4.9


 UNLEADED GASOLINE TANK SLUDGE

R6B-US-01
< 1,650
160
> 3
NA

R8A-US-01
< 1,650
180
> 4
0.09

R16-US-01
< 165
< 50
NA
< 0.09

 CSO SLUDGE

R4-SO-01
41,000
< 50
<3
NA

R9-SO-01
< 20,625
< 50
NA
70

R1B-SO-01
< 20,625
32
3
16

R20-SO-01
< 41,250
76
4
24

 HYDROTREATING CATALYST 

R1-TC-01
4,200
< 50
<24
< 0.05

R8A-TC-01
< 4,125
75
36
NA

R11-TC-01
2,100
790
100
< 0.05

R3B-TC-01
< 165
< 50
NA
< 0.05

R18-TC-01
950
12
25
< 0.05

R22-TC-01
< 165
96
100
< 0.2

 HYDROREFINING CATALYST 

R5-TC-01
< 165
< 50
NA
NA

R7B-RC-01
1,800
150
100
NA

R21-RC-01
170
65
100
0.08

 REFORMING CATALYST 

R2-CR-01
< 165
< 50
NA
NA

R5-CR-01
24,000
490
41
NA

R7B-CR-01
330
< 50
NA
NA

R11-CR-01
< 165
< 50
NA
NA

R14-CR-01
< 165
< 50
NA
NA

R15-CR-01
4,500
< 50
<22
NA

 HF ALKYLATION SLUDGE 

R3-HS-01
32,000
1,200
75
NA

R8B-HS-01
< 1,000
< 50
NA
0.3

R9-HS-01
< 5,157
< 50
NA
31

R15-HS-01
< 2,063
< 50
NA
6.8

R7C-HS-01
< 165
< 50
NA
0.08

 SULFUR COMPLEX SLUDGE 


R1-ME-01
< 6,600
< 50
NA
1.0

R5-ME-01
< 3,300
< 50
NA
NA

R6-ME-01
< 16,500
< 50
NA
NA

R14-ME-01
< 2,063
66
48
0.2

R18-ME-01
< 165
< 50
NA
< 0.05

1 Percent 3/4-methylphenol leached calculated based on a
20 to 1 ratio of leaching fluid to sample mass. The total
concentration was multiplied by 0.05 to obtain the total
theoretical leachate concentration. This value was divided into
the reported TCLP concentration to obtain the percent leached. 
Calculated percentages greater than 100% are listed as 100%
leached.


 Table I.C.7. PETROLEUM REFINING RESIDUALS LEACHING
POTENTIAL 


Sample ID
Total Phenanthrene (g/kg)
TCLP Phenanthrene (g/L)
% Phenanthrene Leached1
% Oil & Grease

 CRUDE TANK SLUDGE

R6B-CS-01
73,000
< 50
<2
24

R8C-CS-01
76,000
< 50
<2
25

R4B-CS-01
380,000
27
<1
15

R10-CS-01
47,000
< 50
<2
41

R19-CS-01
< 11,500
< 50
NA
14

R22-CS-01
7,300
< 50
<14
4.9

 UNLEADED GASOLINE TANK SLUDGE

R6B-US-01
2,400
< 50
<42
NA

R8A-US-01
1,400
< 50
<71
0.09

R16-US-01
< 165
< 50
NA
< 0.09

 CSO SLUDGE

R4-SO-01
200,000
< 50
< 1
NA

R9-SO-01
1,000,000
12
< 1
70

R1B-SO-01
320,000
< 50
< 1
16

R20-SO-01
680,000
< 50
< 1
24

 HYDROTREATING CATALYST 

R1-TC-01
< 660
< 50
NA
< 0.05

R8A-TC-01
400,000
16
< 1
NA

R11-TC-01
< 165
< 50
NA
< 0.05

R3B-TC-01
< 165
< 50
NA
< 0.05

R18-TC-01
< 165
< 50
NA
< 0.05

R22-TC-01
300
< 50
NA
< 0.2

 HYDROREFINING CATALYST 


R5-TC-01
< 165
< 50
NA
NA

R7B-RC-01
2,200
< 50
< 45
NA

R21-RC-01
1,200
< 50
< 83
0.08


 REFORMING CATALYST 

R2-CR-01
14,000
35
5
NA

R5-CR-01
< 660
< 50
NA
NA

R7B-CR-01
< 165
< 50
NA
NA

R11-CR-01
< 165
< 50
NA
NA


R14-CR-01
690
< 50
NA
NA

R15-CR-01
160
< 50
NA
NA

 HF ALKYLATION SLUDGE 

R3-HS-01
4,500
< 50
< 23
NA

R8B-HS-01
< 1,000
< 50
NA
0.3

R9-HS-01
< 5,157
< 50
NA
31

R15-HS-01
< 2,063
< 50
NA
6.8

R7C-HS-01
2,400
< 50
< 42
0.08

 SULFUR COMPLEX SLUDGE 


R1-ME-01
27,000
12
1
1.0

R5-ME-01
< 3,300
< 50
NA
NA

R6-ME-01
< 16,500
< 50
NA
NA

R14-ME-01
14,000
< 50
< 7
0.2

R18-ME-01
580
< 50
NA
< 0.05

1 Percent phenanthrene leached calculated based on a 20
to 1 ratio of leaching fluid to sample mass. The total
concentration was multiplied by 0.05 to obtain the total
theoretical leachate concentration. This value was divided into
the reported TCLP concentration to obtain the percent leached.
 Calculated percentages greater than 100% are listed as 100%
leached.

Comment 6.c: In short, EPA's report is not credible and
does not address the comment that EPA's listing
determination is flawed due to the failure to use the OWEP
in evaluation of the wastes. The report is inaccurate in
its statements and is biased in its analysis of the data
presented in the Tables and the appendices. The report
reflects poor science and improper experimental design in
the manner in which the analytical work was planned in an
attempt to prove a pre-conceived and erroneous conclusion.

In order to account for these problems, KGS modeled various
refinery wastes by applying the average TCLP efficiency of
53% for benzene to the waste streams with a substantial oil
content. For many wastes, the TCLP concentration mean input
value increased significantly as a result, and the
groundwater exposure pathway risk posed by landfilling the
wastes also increased significantly. Based on KGS's
evaluation of this factor and other parameters, the risks
posed by potential mismanagement of most petroleum refinery
wastes covered by the NODA require a hazardous waste
listing, as discussed in Section II [of ETC's comments]
below. (ETC, 00005)

Response: EPA fundamentally disagrees with the commenter. 
The OWEP is not appropriate for use in this listing
determination because: 1) this leaching method is only
applicable to the inorganic metals constituents since any
organic constituents originally present in the solid phase
would be removed with the solvent extraction; and 2)
leaching the solvent extracted solvent phase for organic
target analytes would result in the inaccurate and falsely
low determination of leachate constituents while the
analysis of the solvent phase would more closely resemble
the total concentration. Furthermore, EPA believes that
using an average TCLP leaching efficiency of 53 percent for
benzene is inappropriate and disregards useful information
on individual wastes.

Comment 7: Ineffectiveness of the TCLP on Oily/Tarry Wastes

Comment 7a: Notwithstanding EPA's repeated and longstanding
acknowledgment that the TCLP substantially understates the
leaching potential of oily wastes, the Agency relied on TCLP
results as the input value to the groundwater model for
landfill disposal in the 1995 proposal. EDF commented
extensively on this glaring inconsistency and the inadequacy
of the TCLP for this purpose. Now, instead of admitting
error in this regard, EPA attempts to justify use of the
TCLP through additional analyses in the NODA. As explained
in this section of the comments, the NODA analyses actually
prove the inadequacy of the TCLP for the oily wastes in this
rulemaking.

First, EPA produced lab preparation sample descriptions for
some wastes, and based upon the purported "tarry or granular
consistency" sample descriptions, contends TCLP results are
appropriate because no liquid phase in the waste sample was
observed. However, contrary to EPA's generalization, many
sampling descriptions indicate liquid phases were observed. 
One crude oil tank sludge sample was described as "black and
oily with a consistency of cake icing. Compared to other
centrifuge cakes from other refineries this sludge was more
fluid." A second sample had "a small amount of water
present," even after filtering. Similarly, a CSO sample
"seeped oil out of the filter if squeezed"; an unleaded
storage tank sludge sample had "approximately one inch of
free liquid on the surface"; and three HF alkylation sludge
samples were "black and oily with a high liquid content,"
"yellow with a consistency of wet oily sludge," and had "the
consistency of oil-in-water emulsion". These seven
samples comprise 38% of the 18 EPA samples of crude oil
tank, CSO, HF alkylation, and unleaded storage tank sludges
combined. (ETC, 00006)

Response: The commenter misconstrued the Agency's discussion
in the referenced NODA document (see also response to
Comment 3.b). 

The commenter misinterpreted EPA's description of its field
and laboratory observations when EDF implied that EPA's
statement that "no liquid phase in the waste sample was
observed" was a "generalization" that applied to "many
sampling descriptions". In fact, however, EPA's "no liquid
phase" description was in specific reference to the crude
oil tank sediment samples and was not a generalization that
was meant to be applied to all other samples (in particular,
this statement could not be applied to the HF sludge samples
collected prior to dewatering). With respect to the
specific samples called out by the commenter, EPA disagrees
that the TCLP is inappropriate for their characterization. 
The TCLP filtration step was apparently problem-free with no
instances of filter clogging that were reported by the
laboratory. Any phase separation that occurred during this
filtration step resulted in phases that were, in all cases,
miscible with the TCLP extraction fluid (i.e., not free
phase oil).

Sample R10-CS-01 was characterized in Table 1 of the 1997
Supplemental Listing Background Document [full quotation
provided, in comparison with commenter's paraphrase above]
as "black and oily with a consistency of cake icing. 
Compared to filter cakes or centrifuge cakes from other
refineries this sludge was described as more fluid." This
sample represented crude oil tank sludge, sampled directly
after removal from the storage tank, which was slated for
recycling to the cracking unit. In order for this sludge
to be landfilled, it likely would have been deoiled to
recover the high level of observed hydrocarbons (41 percent
oil and grease) and to ensure that the residual passed the
paint filter test. Even without deoiling, however, no free
liquids were reported by the samplers or the laboratory. 

While collecting sample R19-CS-01 ("a small amount of water
present"), the sampling team observed a "small amount of
water present" in the storage bin due to the rain that had
fallen steadily through the night, however a water phase was
not present in the sample or observed by the laboratory
personnel. (If water had been observed by the laboratory,
this should not have aroused the commenter's concern
regarding free oil content.) As stated in the Supplemental
Listing Background Document, "crude oil tank sediment, the
"oiliest" of all the residuals of concern, was never
observed by the Agency during sampling and analysis to
exhibit an oil phase." As discussed in response to
Comment 1.d, these samples are fundamentally different from
the multi-phase, fluid, difficult-to-filter wastes
characterized in the 1990 RTI report.

Sample R9-SO-01, which was observed by the sampling team to
seep oil while being torn into pieces prior to placement in
sampling containers, was a sample of in-line filters which
remove FCC fines from the slurry oil between the FCC
fractionator and the CSO storage tank. Only 3 refineries in
the U.S. reported performing this type of in-line filtering
prior to storage in the 1992 survey. Each facility
reported storing their filters in drums generating an annual
total quantity of 1.074 MT. 

The paper filter media subsample of R9-SO-01 designated for
non-volatile analyses was composited by manually tearing the
material in order to obtain the most representative sample
for analysis. This process, which also increases the sample
surface area, undoubtedly resulted in the absorption of any
free oil product that may have been present at the time of
sampling. Since no free liquid was present in the composite
mixture at the laboratory, the filtration step for the TCLP
analysis was not necessary. There were no laboratory-
reported method deviations for the TCLP preparation and
analysis of sample R9-SO-01.

The HF alkylation sludges were taken directly from the in-
ground tanks in which they are generated. HF alkylation
sludge is primarily aqueous-based calcium fluoride sludge
with minimal hydrocarbon contamination. Due to sample
availability, the Agency collected four of the five samples
prior to dewatering, their normal treatment prior to
disposal. See response to Comment 1.b, above, for
additional discussion on the generation of HF alkylation
sludge.

The commenter quoted Table 1 of the 1997 Listing Background
Document for R3-HS-01, R15-HS-01, and R9-HS-01. R3 and R15
were collected directly from the neutralization tank, thus
their semi-liquid nature. R3 was decanted at the laboratory
at the refinery's request to better reflect the
characteristics of the waste as it would have been generated
for disposal. R9 was collected from four 55-gallon drums
where it was being stored after removal from the
neutralization tanks (no centrifugation or filtering had
been conducted prior to sample collection). The fifth HF
sample, R7C-HS-01, was collected after centrifuging and was
of a very different consistency that the other "in process"
or "as generated" samples. Thus, the more liquid nature of
the four samples is a reflection of their "as generated"
nature and their derivation from an aqueous neutralization
system. Further, during the initial filtration step of the
TCLP, the filtrate generated for each of these samples was
easily miscible with the TCLP leachate and thus cannot be
characterized as free oil.

Sample R9-HS-01 exhibited oil and grease levels of 31
percent, much higher than the other samples, and much higher
than oil and grease levels reported for HF alkylation sludge
landfilled in Subtitle D units in 1992 (see Table I.C.10 in
response to Comment 8.b, below). The drums holding this
residual were labeled as D001/D002 and EPA's analytical
results confirmed the corrosive nature of this waste with
pH=13. The facility reported in its survey response that
its HF sludge is typically managed at an off-site hazardous
waste landfill. The high oil content of this residual
appears to be due to the refinery's practice of draining its
Acid Soluble Oil (ASO) from its HF regenerator to the
neutralization pit, from which the HF sludge is generated. 
Thus, the inclusion of this sample within EPA's modeling
input is conservative due to the already regulated nature of
the waste.

In conclusion, EPA disagrees with the commenter's
characterization of the samples and its subsequent
conclusion that the TCLP is inappropriate for these wastes
and notes in summary:

 The crude oil sediment samples exhibited no liquid phase,
 despite the Agency's expectation that these would be the
 oiliest of all the RCs studied, aside from a small amount of
 rainwater observed in one waste storage bin.

 The CSO filter sample was not filtered by the laboratory
 based on its observation of the sample.

 The free liquid associated with the unleaded gasoline
 sludge was a characterization of the material remaining
 in the storage tank at the time of sampling and was not
 sampled.

 The liquid nature of the HF sludge samples is a
 reflection of the collection of these samples directly
 from the neutralization tank (for 3 of the samples) or
 from dredged sludge held in drums which had not been
 dewatered. TCLP filtration of these samples resulted in
 a filtrate that was easily miscible with the TCLP
 leachate and there was no indication of filtration
 difficulties such as those encountered in the 1990 RTI
 study.

Comment 7.b: In other instances, the samples were
inappropriately manipulated to discourage the detection of
free liquids. For example, EPA allowed CSO sludge to be
mixed with cement kiln dust prior to sampling, thus the
sample did not reflect the liquid content of the CSO sludge
itself. One other CSO sludge sample and an unleaded storage
tank sludge sample were "air dried," thereby allowing the
free liquid to evaporate and toxic contaminants such as
benzene to volatilize. Two HF alkylation sludges were
"dewatered" prior to sampling or at the laboratory prior to
analysis. Given these sampling practices, and the liquids
observed in other samples, the sampling descriptions do not
justify reliance on the TCLP in the instant rulemaking. 
(EDF, 00006)

Response: As discussed in response to Comment 1.b, above,
EPA attempted to collect samples that were representative of
the wastes after the wastes were removed from the generating
units. Stabilization with materials such as cement kiln
dust is not uncommon. EPA did not "allow" the CSO sludge to
be mixed with cement kiln dust, but did note that this had
already occurred prior to arrival of EPA's contractor team
on-site. In regards to the CSO sample, all of the samples
were below the detection limit for benzene and many of the
other volatile constituents demonstrating that air drying of
the tank had little to no effect on the sample's volatile
contents as discussed further in response to Comment 1.a.

The "air dried" unleaded gasoline and CSO sludge samples, as
discussed earlier in response to Comment 1.a, were being
managed in a manner consistent with practices designed to
lower benzene and LEL levels to allow safe working
conditions for the personnel conducting the tank
turnarounds. Further, this is a "typical" management
practice for unleaded tank sediment as observed during site
visits to other refineries and from RCRA 3007 survey
results. At the sampled refinery, the tank was water
washed, allowed to dry, and then solids were drummed. Water
washing was reported to be a common technique reported
during the site visits. Additionally, more than 85 percent
of the facilities cleaning a tank since 1991 reported
washing, most often with water (Waste Minimization for
Selected Residuals in the Petroleum Refining Industry,
December 1996). EPA has insufficient data to determine the
frequency of "air drying".

One HF sludge sample, R3-HS-01, was collected directly from
the neutralization pit and was filtered by the lab to better
characterize the waste as it was to be disposed. The liquid
portion of the Exxon sample was decanted and analyzed for
volatiles only. Based on the low volatile concentrations in
the liquid phase, this phase appears to be an aqueous and
not an oil phase. The other HF sludge sample of concern to
the commenter, R7C-HS-01, was of sludge which had been
centrifuged and was awaiting transport to an offsite
municipal landfill. EPA believes that this sample is
particularly representative of HF sludge as disposed.

Comment 7.c: Further, the lack of primary leachate
generation during initial filtration recorded by EPA in the
NODA Background Document for the above wastes, and the other
"tarry" sludges, merely confirms EPA's previous findings
that the TCLP understates the leachability of difficult-
to-filter wastes, particularly for "tarry wastes". In the
1990 EPA contractor report on the TCLP, the authors noted
that no liquids were expressed from the filter before the
specified filtration time had elapsed, because the filter
"greatly over predicts percent solids". The filter "was
therefore deemed inaccurate for oily wastes". 

Significantly, when utilizing soil column results not
limited by the TCLP filter, EPA's contractor found that
large proportions of the oily waste were released as primary
leachate. Moreover, when the TCLP filter was modified,
the results more closely resembled the soil column tests. 
Since the primary leachate accounts for a large proportion
of the toxic contaminants released from the waste in the
soil column tests, the lack of primary leachate generation
from the oily wastes in the instant rulemaking is part of
the problem, not an indication the TCLP is appropriate. 
(EDF, 00006)

Response: See responses to Comments 1.d and 7.g.

Comment 7.d: Second, EPA assessed the TCLP's benzene
leaching efficiency for various wastes. Unlike mere sample
descriptions, leaching efficiency calculations provide a
direct measurement of TCLP benzene performance for various
wastes. According to EPA, the average leaching efficiency
for the 27 samples where such an efficiency could be
calculated was 53%, and this efficiency "was fairly
consistent" regardless of the oil content of the waste.

Again, a closer look at the actual data proves the
inadequacy of the TCLP on the oily wastes in this
rulemaking. Of the 27 samples in EPA's data base, only six
have both an oil/grease content greater than 1% and a
benzene efficiency value. Five of the six samples are crude
oil storage tank sludge. Three of these five samples have a
benzene leaching efficiency of 32% or less, with the lowest
at 15%. (EDF, 00006)

Response: The commenter correctly notes that six samples
have both an oil and grease content above 1 percent and a
calculated benzene leaching efficiency (see Supplemental
Listing Background Document). The average of these six
values is 53 percent, identical to the average leaching
efficiency of other samples representing reforming catalyst,
hydrotreating catalyst, hydrorefining catalyst, sulfur
sludge, unleaded tank sludge, and hydrotreating catalyst. 
Further, several samples with low oil and grease also have
low benzene leaching efficiency, such as samples of unleaded
gasoline tank sludge and hydrorefining catalyst. Therefore,
EPA reiterates its conclusion that oil and grease is not an
accurate predictor of leaching efficiency based on the
analyses presented in the NODA.

The commenter is concerned that only six of 27 samples have
both a benzene efficiency value and an oil and grease
content greater than 1 percent. EPA notes that only 11
samples had oil and grease content above 1 percent to begin
with, and that benzene leaching efficiencies could not be
calculated for the remaining five samples because benzene
was not detected in both total and leachate, and such a
calculation would be meaningless.

With respect to the commenter's footnote regarding the OWEP
analyses, see earlier responses to Comments 3.a and 5.

Comment 7.e: Indeed, crude oil tank sludge and
hydrotreating catalyst samples comprise the vast majority of
all samples with both an oil/grease % and a benzene capture
efficiency value. In the case of hydrotreating catalysts,
where the oil/grease % recorded in the data base is well
below 1%, the average benzene capture efficiency is 72.8%. 
In contrast, the average crude oil tank sludge benzene
leaching efficiency is 43%. Therefore, the TCLP was
substantially less effective in capturing benzene on the
waste with the higher oil/grease content. (EDF, 00006)

Response: The average calculated benzene efficiency levels
cited by the commenter are correct. Additional waste-
specific benzene efficiencies can be calculated for each of
the wastes, as follows (only wastes with three or more
leaching efficiency data points are presented):


 Table I.C.8. Benzene Leaching Efficiencies


Residual
Average Benzene Efficiency (%)
PRDB Mean Oil &Grease (%)*
PRDB Median Oil % Grease (%)
EPA Analytical Data Mean Oil & Grease (%)**

Hydrotreating catalyst 
73 
3.6
0.35
ND

Reforming catalyst 
69 
1.0
0.01
NA

Hydrorefining catalyst 
49
12.5***
2.5
0.08

Crude oil tank sludge 
43 
34.3
2.5
20.6

Unleaded tank sludge 
33
10.81
6.1
0.09

 *1995 Listing Background Document
 **1997 NODA Supplemental Background Document, assumed
non-detect values were equal to the detection limit.
 ***Corrected value.

Table I.C.8 shows that the benzene leaching efficiency of an
"oily" waste (crude oil tank sludge) can be either higher or
lower than wastes that are less oily. Further, Table
I.C.9 shows that within a residual category there is
variability and no clear pattern:


 Table I.C.9. Crude Oil Tank Sludge Leaching Efficiency


Sample Number
Benzene Efficiency
Oil and Grease (%)

R19-CS-01
97
14

R6B-CS-01
49
24

R4B-CS-01
32
15

R10-CS-01
22
41

R8C-CS-01
15
25

R22-CS-01
NA, benzene not detected
4.87


EPA continues to conclude that leaching efficiency is not
well correlated to oil and grease content. Even if the TCLP
was less effective for oily samples of crude oil tank
sediment, this is essentially no longer relevant because EPA
has decided to list this waste as hazardous.

Comment 7.f: Furthermore, the actual benzene leaching
efficiencies used in EPA's groundwater modeling, where the
values matter the most, are much lower than 53% for most of
the oily sludges EPA does not propose to list as hazardous
in this rulemaking. In the case of crude oil storage tank
sludge, the modeled TCLP benzene leaching efficiency was 23%
for the median value, and 15% for the high-end value. 
Similarly, when EPA modeled the landfilling of HF alkylation
sludge, the TCLP benzene leaching efficiency was 35% and 25%
for the median and high-end values respectively. And the
benzene leaching efficiency for unleaded storage tank sludge
is 28% for the median value. Accordingly, TCLP benzene
capture efficiencies used in the groundwater modeling for
these oily sludges are roughly one-half of EPA's so-called
average value, and approximately one-third of the
hydrotreating catalyst with lower oil/grease content.

KGS modeled various refinery wastes using all EPA value
inputs, except the TCLP values were adjusted to reflect
EPA's purported average benzene leaching efficiency. In the
case of crude oil storage tank sludge, the TCLP
concentration mean input value increased from 0.678 mg/l to
1.56 mg/l, and the resulting groundwater exposure pathway
risk posed by landfilling this waste almost doubled from the
2.7x10-5 risk computed by EPA to the KGS result of 4.8x10-5. 


In the case of HF alkylation sludge (offsite), the TCLP
value was a high-end parameter in EPA's deterministic
modeling, consequently modifying the TCLP value to reflect
the purported 53% average benzene leaching efficiency more
than doubled the resulting risk. The TCLP value increased
from 0.18 mg/l to 0.371 mg/l, and the resulting groundwater
use risk increased from 6.4x10-6 to 1.5x10-5. Therefore,
had EPA's TCLP values for oily wastes actually reflected the
benzene leaching efficiency EPA claims, the modeling results
would be substantially different. (EDF, 00006)

Response: The commenter compared the TCLP and total benzene
concentrations corresponding to 50th percentile and 90th
percentile concentrations to calculate "actual"
efficiencies. EPA disagrees with this assessment and
believes that these are not actual efficiencies at all
because they are not necessarily taken from the same sample. 
Such 50th and 90th percentile values were used in conducting
2 parameter high end modeling scenarios for both the NODA
and the 1995 proposal. For the Monte Carlo analysis,
however, paired total and TCLP values were used (see page
4-2 of the Groundwater Supplemental Background Document) and
therefore the comment is not applicable to the Monte Carlo
results.] EPA disagrees with the commenter's decision to
change the concentration input data for the ground water
modeling analyses. EPA does not observe a strong correlation
between "oiliness" and extraction efficiency as discussed
above. EPA fundamentally disagrees that the TCLP results
are inappropriate for these residuals. EPA conducted record
sampling to measure total and leachate values for use as
risk assessment inputs and believes these values to be
appropriate and representative of the population of wastes. 
The commenter does not provide a compelling reason to
increase the leachate value used as the ground water
modeling input. To incorporate the commenter's suggestion
to maintain leaching efficiency as constant, EPA could
increase the leachate concentration (as suggested by the
commenter), or even decrease the total concentration while
holding the measured leachate value constant. EPA does not
see the benefit of either approach in assessing risks.

EPA also wishes to again correct the commenter's suggestion
that unleaded gasoline tank sludge is an "oily" waste. As
presented in the Supplemental Background Document, the oil
and grease content of two of the three samples are well
below 1 percent (the oil and grease content of the third
sample was not reported). This waste demonstrates a case
where somewhat lower benzene leaching efficiencies are
observed in wastes with low oil and grease contents.

Comment 7.g: More fundamentally, however, because of the
lack of primary leachate generation using the TCLP, even
these benzene leaching efficiencies understate the magnitude
of the TCLP shortcomings in the instant rulemaking. Where
primary leachate is generated, it is not subject to the 20-1
dilution factor that EPA used to calculate its "benzene
leaching efficiency" values. Therefore, when EPA's
contractor used a modified filter that would allow for
primary leachate generation of oily wastes, 20.3% of the
benzene in slop oil emulsion was extracted into the
leachate. Only 0.8% of the benzene in the waste was
recovered by the contractor in the leachate using the
TCLP. For comparison purposes, EPA's benzene recovery
percentages (derived by dividing the TCLP value by the waste
benzene concentration without applying the 20-1 dilution
factor) in the instant rulemaking (using median values) are
1.2% for crude oil tank sludge, 1.8% for HF alkylation
sludge, and 1.5% for unleaded storage tank sludge. 
Accordingly, the TCLP may understate the leachable benzene
concentrations by a factor of 10 or more, an understatement
not fully reflected by merely adjusting the TCLP benzene
leaching efficiency to 53% after applying the 20-1 dilution
factor. (EDF, 00006)

Response: For samples with >0.5% solids content, the
commenter is incorrect in stating that "where primary
leachate is generated, it is not subject to the 20-1
dilution factor that EPA used to calculate its "benzene
leaching efficiency" values." Conversely, the concentration
detected in the primary leachate or initial filtrate,
assuming initial filtrate and leachate are not compatible
and require separate analyses, are combined mathematically
based on the following calculation as presented in Method
1311:

 where:

 V1 = The volume of the first phase filtrate
(L)
 C1 = The concentration of the analyte in the
 first phase filtrate (mg/L)
 V2 = The volume of the second phase leachate
 (L)
 C2 = The concentration of the analyte in the
 second phase leachate (mg/L).
 
Using this equation it is apparent that any analyte
concentration detected in the initial filtrate will be
diluted by some factor depending of the sample solids
content. For example, suppose a waste was found to contain
a 40% liquid phase or 0.01 L of filtrate based on a 25 gram
sample used for the zero headspace extraction (ZHE)
procedure. The solid phase or 15 grams would require 0.3 L
of extraction fluid based on the method required 20 to 1
ratio of fluid to sample weight. Assuming a worst case
scenario in which benzene is detected almost entirely in the
filtrate at a concentration that resembles the total
concentration of 100 m/L, the maximum theoretical solid
phase leachate concentration would be 5 mg/L. Using these
values with the equation listed above, the final leachate
concentration would be 8.1 mg/L which represents a 12-fold
dilution from the filtrate only concentration. Since the
final leachate concentration for non-compatible phases is a
combination of the initial filtrate and solid phase leachate
concentrations, the amount of filtrate concentration
dilution is directly proportional to the sample solids
content. A higher solids content results in a greater
filtrate concentration dilution. Only in situations where
the sample % solids content was <0.5%, the filtrate volume
would be considered the leachate and the detected
concentration would represent the final leachate
concentration.

As stated previously, the Agency does not believe the wastes
described in the RTI document are comparable to the
petroleum refining residuals. Furthermore, it should be
noted that the leachate recoveries of benzene in the slop
oil emulsion as presented in the RTI report are calculated
differently since the values were calculated from the total
concentration without considering the extraction fluid
dilution.

Comment 7.h: Significantly, EPA did not even conduct
comparable TCLP efficiency analyses for PAHs. The data
available indicates if it had, the results would be even
more dramatic. For many oily wastes, high concentrations of
PAHs were detected in the waste, but none were detected in
the TCLP extract. 

For example, in the case of CSO sludge, even though waste
samples contained up to 390 ppm benz(a)anthracene, 230 ppm
benzo(a)pyrene, and 860 ppm chrysene, the TCLP values used
for groundwater modeling purposes were non-detect. 
Similar TCLP non-detects were observed for crude oil tank
sludge, notwithstanding total concentrations of
benz(a)anthracene of up to 49.5 ppm. Off-spec thermal
product and fines is the only waste where PAHs were detected
in the TCLP extract. For the sample containing the highest
totals contaminant concentration (28 ppm), the TCLP
benz(a)anthracene leaching efficiency (using the 20-1
dilution factor) is less than 4%. 

This phenomenon of measuring PAH non-detects in TCLP
samples, but measuring substantial PAH leaching when using
improved leaching procedures, is exactly what EPA's
contractor observed when assessing the shortcomings of the
TCLP in 1990. Indeed, the EPA contractor measured the
leachability of semivolatiles (including PAHs) using the
modified filter, and found them roughly comparable to the
"real world" soil column testing results. Moreover, in
those instances where the TCLP allowed primary waste
generation, the TCLP results closely resembled the modified
filter values. 

Using the modified filter, slop oil emulsion leached 4.06
mg/l benzo(a)anthracene from waste containing an average
20.5 ppm of the PAH. Similarly, 4.21 mg/l chrysene leached
from the same waste containing an average 33.3 ppm of the
toxic chemical. Accordingly, the leachate recovered
between 12.5-20% of these chemicals found in the wastes. 
For comparison purposes, in the case of the one waste (off-
spec products and fines) where PAHs were detected using the
TCLP in the instant rulemaking, the benz(a)anthracene and
benzo(a)pyrene leachate recovery rates were approximately
0.1% for the samples containing the highest concentration of
these contaminants. With respect to the other oily wastes
in this rulemaking, notwithstanding greater concentrations
of these and other contaminants, the leachate contaminant
recovery rate was essentially zero. 

KGS used EPA's groundwater model to compute the PAH leachate
value necessary to produce a 1x10-4 risk level in the
receptor well for CSO sludge and off-spec products and
fines. Using modified input values for volumes (for the
reasons discussed in Sections II.D and II.E), and locating
the well in the plume centerline (as discussed in Section
II.F), KGS determined leachate values of only 0.017 mg/l
benz(a)anthracene or 0.026 mg/l of chrysene would yield the
10-4 risk at the receptor well for the CSO sludge onsite
scenario. These leachate values represent 0.008% of the
benz(a)anthracene and 0.005% of the chrysene in CSO sludge,
when compared to average CSO sample results. The PAH
leaching efficiency analogous to EPA's benzene leaching
efficiency calculation (i.e., applying the 20-1 dilution
factor) necessary to produce these leachate values are 0.17%
(benz(a)anthracene) and 0.11% (chrysene), again compared to
average waste concentrations.

Similarly, KGS determined leachate values of 0.0115 mg/l 
benz(a)anthracene or 0.125 mg/l chrysene would produce a
10-4 risk at the receptor well for the off-spec product and
fines offsite scenario. These leachate values represent
0.01% of the benz(a)anthracene and 0.5% of the chrysene in
the waste, when compared to average off-spec product and
fines sample results. The leaching efficiency necessary
to produce these leachate values (applying the 20-1 dilution
factor) is 1.9% for benz(a)anthracene and 10.4% for
chrysene.

Significantly, these leachate values corresponding to the
10-4 risk assume only that individual constituent will reach
the receptor well. Since benz(a)anthracene and chrysene can
be expected to travel at approximately the same velocity,
even lower leachate values would produce the same
unacceptable risk for the two chemicals combined. 

Therefore, in the case of CSO sludge and off-spec products
and fines, high groundwater risks will result from extremely
small fractions of the PAH contaminants leaching from the
landfill, without even accounting for facilitated transport
associated with refinery sites as discussed in Section II.C
below. On the basis of EPA's previous positions regarding
the efficacy of the TCLP on oily wastes, EPA's contractor
report demonstrating the poor performance of the TCLP on
PAHs in oily wastes, EPA's data indicating CSO and off-spec
products and fines contain high percentages of oil and
grease, and the potential for CSO sludge to contain free
liquid, it is more than plausible that these wastes will
leach PAHs at the extremely small concentrations which pose
a substantial risk to human health and the environment. 
(EDF, 00006)

Response: EPA notes that it is not possible to calculate
extraction efficiencies for the PAHs because the TCLP
results were generally non-detects for these compounds. 
This was not surprising considering the highly hydrophobic
nature of these compounds and as illustrated below for the
CSO sludge PAHs highlighted by the commenter:


PAH Solubility (mg/L)*

Benz(a)anthracene 0.0128
Benzo(a)pyrene 0.00194
Chrysene 0.00194

 * Solubilities as reference in the technical background
 document, Nongroundwater Risk Assessment for Petroleum
 Refining Waste Listing Decision: Uncertainty Analysis. 
 1997.

Significant risk for these compounds, however, was
identified for the indirect exposure pathways, largely due
to the same hydrophobic properties that minimize risk from a
groundwater perspective.

Further, EPA notes that the PAH leachate levels associated
with the coke fines are highly problematic as previously
discussed in the April 1997 NODA at 62 FR 16751.

EPA notes an error in the comment. Of the four off-spec
product and fines record samples analyzed for oil and grease
content, three of the samples had oil and grease contents
less than 1 percent and the fourth had a level of 8.4
percent. See NODA Supplemental Listing Background Document,
Chapter 2, Table 1. This is in contrast to the commenter's
claim that 2 of 4 such samples have oil and grease contents
of 10 percent.
 
EPA refers the reader to the response to Comment 1 regarding
the validity of the commenter's concern about free liquids
in the CSO samples and the validity of the Agency's sampling
protocols.

EPA disagrees that the commenter's purely hypothetical
analysis indicates that PAHs present a substantial risk via
leaching to groundwater. Based on the existing TCLP data,
as well as the demonstrated insolubility of PAHs in water,
EPA does not believe such an analysis is correct.

Comment 8: TCLP Fails to Account for Co-disposal with
Solvents or Oils 

Comment 8.a: In addition to the problems associated with
the procedure itself, the TCLP is inappropriate because it
measures only the dissolved phase flow of contaminants into
the groundwater, and thus fails to consider the cosolvency
effects of oil and other compounds in the landfill. In the
previous petroleum refinery listing determination, the
Agency expressly acknowledged the cosolvency effects
associated with the solvents and oils present in petroleum
refinery land disposal facilities.

 However, evidence exists that [PAHs] may move more
 rapidly in soil with low organic content or if
 codisposed with other solvents or oils. Because
 wastes listed today typically contain high
 concentrations of oils, the mobility of the PAHs
 is expected to be quite high due to cosolvent
 effects. Therefore, it is reasonable to assume
 that wastes containing these constituents could
 pose a significant threat to human health via
 groundwater contamination if mismanaged.

Response: EPA notes that the FRN passage quoted by the
commenter reflects the Agency's views at that time regarding
co-solvency effects within the F037/F038 sludges, as opposed
to any co-solvent effects due to co-disposal with other
mobilizing wastes. Further, the 1990 sludge listing was
based primarily on the results of totals analysis; the TCLP
analyses that were conducted in support of this effort were
completed prior to the 1988 NODA for the sludge listings. 
The TCLP itself was not promulgated until March of 1990. 
Thus, the TCLP was essentially still a developmental method
during the data collection phase of the sludge listing
determination. In retrospect, if the TCLP had been
available as an established method during data development,
EPA could have argued that co-solvent effects within the
wastes were measured by the TCLP. In fact, the 1990 RTI
report concluded that API separator sludge, which is quite
similar to F037/38, did not exhibit TCLP filtration
problems:

 "Method 1311 did, however accurately estimate the
 mobile and immobile fractions of API separator sludge
 determined in the column experiments, suggesting that
 it is suitable as written for oily wastes that are not
 difficult-to-filter." p. 79.

Note: the commenter characterized the TCLP as measuring
"only the dissolved phase flow of contaminants". As
discussed further in response to Comment 7.g, the method
also assesses any filtrate generated during the initial
filtration step (issues of oily waste non-filterability
aside), regardless of whether the filtrate is aqueous or
nonaqueous.

Comment 8.b: Notwithstanding this express finding of co-
disposal potential in refinery waste landfills made by the
Agency in 1990, in the NODA materials the Agency minimizes
the prospect of co-disposal with oil and solvents solely on
the basis of oil and grease content data on selected waste
samples. As discussed in this portion of the comments, the
survey results are extremely incomplete and therefore
provide an insufficient basis for overriding the express
finding made in 1990.

First, oil and grease data were reported on only 48 of 127
residuals disposed in onsite landfills, and only 120 of 621
residuals disposed in offsite landfills, thereby accounting
for only 22% of all landfilled residuals in EPA's data
base. Perhaps more importantly, very few of the reported
values involved the oily wastes in this rulemaking. 

For onsite landfilling, no CSO sludge, and only two unleaded
gasoline storage tank and one HF alkylation sludge values
are included in the data base. In contrast, 12 samples of
treating clay from alkylation were included in the data
base. 

For offsite landfilling, only one crude oil tank sludge and
unleaded storage tank sludge sample, five CSO sludge
samples, and three HF alkylation sludge samples are included
in the data base. In contrast, EPA's data base contains
20 samples of off-spec product from sulfur complex and H2S,
and 14 samples of sulfur removal sludge. 

Therefore, median or average values computed by EPA are
virtually meaningless since the data base largely reflects
nonoily wastes, and there is no rationale for the large
variation in number of samples included for each waste type
(other than availability of data). (EDF, 00006)

Response: EPA disagrees that the median oil and grease data
presented in the NODA are meaningless. The NODA
Supplemental Background Document for Listing Support
Analyses summarizes the available oil and grease data for
all wastes that were managed in nonhazardous landfills in
1992. For onsite landfills, the median oil and grease
content of disposed wastes was less than 1 percent. For
offsite landfills, the median oil and grease content of
disposed wastes was approximately 1 percent. The commenter
subsequently requested (and received) the supporting data
for this summary, which itemizes the oil and grease content
of each of the approximately 170 (120 offsite and 48 onsite)
wastes used in the calculations. As discussed below, EPA
believes that the data are representative of both oily and
nonoily wastes, contrary to the commenter's conclusions.

The oil and grease data cited by the commenter are based on
the results of the RCRA 3007 survey. Respondents were
required to submit available data characterizing each
residual and, if necessary, to use judgement in estimating
properties (respondents were not required to conduct testing
specifically for the survey). Therefore, the quality of the
oil and grease data submitted, as well as other waste
characterization data, was wholly dependent on the
availability of data at each refinery. Given this
situation, wide variability in the data base
representativeness is expected, with oil and grease data
availability much greater for some waste categories than for
others. As the commenter correctly points out,
approximately 22 percent of all the landfilled residuals had
oil and grease data. These data are summarized in Table
I.C.10. As explained further below, some landfilled wastes
have relatively more oil and grease data than others.


 Table I.C.10. Oil and Grease Content of Refinery Wastes
 Disposed in Onsite and Offsite Subtitle D Landfills in 1992

Residual; Number of Values; 50th percentile, %; Maximum, %

Desalting Sludge; 5; 10; 20
Residual Oil Tank Sludge; 3; 28*; 99*
Treating Clay from Clay Filtering; 18; 1; 23
Treating Clay from Isomerization/ Extraction; 5; 1; 5
Hydrocracking Catalyst; 2; 5; 9
Process Sludge from Residual Upgrading; 1; 5; 5

Off-Spec Sulfur; 23; 0; 13
Reforming Catalyst; 1; 1; 1
Polymerization Catalyst; 5; 0; 2
Treating Clay from Alkylation; 17; 0; 1
CSO Sludge; 5; 5; 20
Crude Oil Tank Sludge; 1; 80*; 80*
Hydrotreating Catalyst; 7; 9; 9
Sulfur Sludge; 16; 0; 5
Off-spec Product and Fines from Thermal Processes; 4; 6; 14
Unleaded Gasoline Tank Sludge; 3; 5; 5
Hydrorefining Catalyst; 1; 9; 9
FCC Catalyst; 17; 0; 1
FCC Fines; 19; 0; 1
Sulfur Complex Catalyst (Claus); 11; 0; 2
Sulfur Complex Catalyst (SCOT); 2; 0; 0
HF Alkylation Sludge; 4; 1; 3

The commenter calls out nine specific residuals: crude oil
tank sediment, CSO sediment, unleaded storage tank sludge,
residual oil tank sludge, HF alkylation sludge, off-spec
product from sulfur processes, sulfur removal sludge,
treating clay from clay filtering, and treating clay from
alkylation. The commenter notes that the number of wastes
with oil and grease data varies widely. However, the number
of wastes landfilled also varies widely. Comparing the
number of wastes with oil and grease data to the number of
wastes landfilled allows for a more appropriate and
normalized comparison. Such "coverage" of oil and grease
data for these specific wastes are as follows (sources of
all data are the "EPA Oil/Grease Landfill Data" cited by the
commenter, the 1995 Listing Background Document, and the
1996 Study; all data are for 1992):

 For HF alkylation sludge, 3 of 8 wastes disposed
 offsite and 1 of 1 waste disposed onsite reported oil
 and grease content (overall coverage is 4 of 9 wastes,
 or 44 percent).

 For off-spec product from sulfur processes, 20 of 51
 wastes disposed offsite and 3 of 3 wastes disposed
 onsite reported oil and grease content (overall
 coverage is 23 of 54 wastes, or 43 percent).

 For treating clay from alkylation, 5 of 30 wastes
 disposed offsite and 12 of 18 wastes disposed onsite
 reported oil and grease content (overall coverage is 17
 of 48 wastes, or 35 percent).

 For CSO sediment, 5 of 16 wastes disposed offsite and
 0 of 2 wastes disposed onsite had oil and grease
 content (overall coverage is 5 of 18 wastes, or 28
 percent).

 For treating clay from clay filtering, 14 of 91
 wastes disposed offsite and 4 of 15 wastes disposed
 onsite reported oil and grease content (overall
 coverage is 18 of 106 wastes, or 17 percent).

 For residual oil tank sludge, 3 of 17 wastes disposed
 offsite and 0 of 3 wastes disposed onsite had oil and
 grease content (overall coverage is 3 of 20 wastes, or
 15 percent).

 For sulfur removal sludge, 14 of 110 wastes disposed
 offsite and 2 of 18 wastes disposed onsite reported oil
 and grease content (overall coverage is 16 of 128
 wastes, or 13 percent).

 For unleaded storage tank sludge, 1 of 35 wastes
 disposed offsite and 2 of 3 wastes disposed onsite
 reported oil and grease content (overall coverage is 3
 of 38 wastes, or 8 percent).

 For crude oil tank sediment, 1 of 25 wastes (4
 percent) disposed offsite had oil and grease contents
 (no wastes were disposed onsite).

The above comparison shows that, for the nine wastes
mentioned by the commenter, four are "over-represented" in
the data base while five are "under-represented," i.e., the
actual number of landfilled samples with oil and grease
content is higher ("over-represented") or lower ("under-
represented") than 22 percent. Among the wastes with a
higher than average number of landfilled samples with oil
and grease data are HF alkylation sludge and CSO sediment,
two of the four wastes claimed by the commenter to be
lacking in data. 

It is important to note that the commenter's evaluation
differentiates between data reported for on-site and off-
site landfilling; EPA's analysis presented above is based on
the premise that data from these 2 subsets can be combined. 
Thus, while the commenter is concerned that oil and grease
data for CSO sludge landfilled on-site is lacking (only 2
such sludges were reported to be landfilled on-site in
1992), overall, EPA's analysis shows that the industry
reported O&G data for 28 percent of wastes landfilled
(regardless of whether the management occurred on-
or off-site).

The primary reason EPA believes that there are more oil and
grease data for sulfur removal sludge than for HF alkylation
sludge (for example) is, in part, simply that a greater
number of sulfur removal sludge wastes than HF alkylation
sludge wastes are landfilled. EPA acknowledges that some
wastes are not well represented in the database (such as
crude oil tank sediment and unleaded tank sediment), but
believes that others of concern to the commenter are fairly
well represented (such as treating clay from clay filtering)
and others are very well represented (such as HF alkylation
sludge) when the more appropriate normalized approach
presented above is used.

Comment 8.c: Indeed, many of the wastes codisposed in
highest volumes onsite (CSO sludge, HF alkylation sludge,
treating clay from clay filtering) are the wastes with
substantial oil content. Similarly, in the case of
offsite landfilling, the higher volume wastes contained a
substantial percentage of oil (CSO sludge, HF alkylation
sludge, residual oil sludge). (EDF, 00006)

Response: As discussed above in response to Comment 8.b, the
Agency's normalized assessment of the availability of O&G
data is helpful in evaluating and alleviating the
commenter's concerns. For CSO sediment, HF alkylation
sludge, and treating clay from clay filtering, the
"coverage" of oil and grease data in the data base is 28,
44, and 17 percent, respectively, which compares favorably
with the overall coverage of 22 percent described in the
NODA. The median oil and grease content of these wastes
when landfilled was 5, 1, and 1 percent, respectively (as
discussed in response to comment 8.b above). EPA disagrees
that these results should be characterized as demonstrating
"substantial oil content".

Overall, as previously argued by EPA in Section 2.2 of the
March 1997 Supplemental Background Document, the residuals
of concern infrequently exhibit oil and grease contents
above 10 percent. EPA identified 13 wastes disposed in
offsite Subtitle D landfills with oil and grease contents
equal to or greater than 10 percent, and 1 waste disposed in
an onsite Subtitle D landfill with an oil and grease content
equal to or greater than 10 percent (in the Supplemental
Listing Background Document to the NODA, EPA presented its
evidence suggesting that 2 of these 14 residuals have actual
oil and grease levels lower than reported). The median oil
and grease content for residuals landfilled either off- or
on-site was equal to or less than 1 percent. EPA believes,
especially within the context of the commenter's concern
regarding co-disposal, that these low median values
demonstrate little potential for enhanced toxicant mobility. 
Furthermore, the Agency notes that higher levels of oil and
grease, such as the 14 residuals landfilled with oil and
grease levels equal to or greater than 10 percent do not
necessarily correspond to high levels of free oil, as
discussed at length earlier in this section.

As a means of addressing the commenter's concern regarding
high volumes of oily wastes in the co-disposal scenario, EPA
calculated a hypothetical volume-weighted oil and grease
value. Specifically, if all 120 residuals managed in
nonhazardous offsite landfills in 1992 with oil and grease
data were disposed in a single landfill, the overall volume-
weighted oil and grease level would be 4 percent. If two
wastes were removed (i.e., the wastes with oil and grease
values of 80% and 99% which the NODA background document
state are not indicative of landfilled wastes), the overall
volume-weighted oil and grease level decreases to 3 percent. 
This compares favorably to the overall median value (given
in the NODA Background Document) of approximately 1 percent. 
The results for the onsite analysis are similar. If all
residuals with oil and grease data managed in nonhazardous
onsite landfills were disposed in a single landfill, the
overall volume-weighted oil and grease level would be much
less than one percent. If one waste was removed (i.e., a
single low-oil waste generated in a very large volume), the
overall volume-weighted oil and grease level increases to
just 0.5 percent, which compares favorably to the overall
median value given in the NODA Background Document, of less
than 1 percent. EPA concludes that the higher volume wastes
do not contain a substantial percentage of oil, as claimed
by the commenter, because the above analysis shows similar
results using a volume-weighted approach and the original,
overall median approach.

Comment 8.d: For example, the third highest volume waste
codisposed offsite - residual oil sludge - consistently
exhibited oil content much greater than 10% in EPA's data
base, ranging in oil content up to 99%. The highest
volume codisposed waste - HF alkylation sludge - has a mean
oil/grease content of 2.68%, and a 90% value of 5% oil and
grease. EPA's sampling descriptions of HF alkylation
sludge typically indicated the waste has a liquid phase or
high liquid content.

Response: First, EPA reiterates that the 99 percent value of
oil and grease cited by the commenter for residual oil tank
sludge is incorrect for the reasons stated in Appendix A of
the Supplemental Listing Background Document. EPA contends
that it is completely inappropriate to assume that the 99
percent value represents the true oil content of a material
that could be landfilled. For the residual in question, the
survey clearly reports that this residual underwent de-
oiling prior to landfilling. The facility did not estimate
the oil and grease content of de-oiled sludge for this
stream. The facility did estimate the liquid and solid
quantities of material generated from the process. 
Specifically, the facility estimated the volume reduction at
2 percent (which is much lower than for other facilities and
shows that the level of oil and grease following "de-oiling"
is approximately the same as the level prior to de-oiling). 
EPA believes that the low level of free oil recovered shows
that very little free oil is left in the waste to migrate. 
The low quantity of oil recovered shows that the material
did not have much free oil to begin with. In regard to the
high levels of reported oil and grease, EPA believes that
this is due to the nature of the matrix (i.e., residual oil
tank sludge). Because this waste is generated from the
settling of heavy oil, it will generally consist of heavy
hydrocarbons. Note that residual oil itself is very "heavy"
and typically must be warmed to be pumped. The material
settling from these tanks, therefore, can be expected to be
very high molecular weight and solid.

De-oiling does produce wastes with varying oil contents;
see, for example, the oil and grease content of record
samples presented in the Supplemental Listing Background
Document, where the oil and grease content of de-oiled crude
oil tank sludge ranges from 5 to 15 percent. By definition,
however, the oil content of a de-oiled sludge would be less
than its oil content prior to that step. Therefore, for the
wastes referenced by EPA in the Supplemental Background
Document as representative of "pre-" de-oiling, the de-
oiling process produces a volume-reduced sludge and
recovered oil; the oil content of the volume-reduced sludge
is obviously less than that in the starting material. 
Regardless of the frequency that de-oiling is used in the
industry (see below), EPA knows that the wastes in question
by the commenter did, in fact, undergo de-oiling.

Second, with respect to the HF alkylation sludge oil and
grease data, the commenter is using data representing all HF
sludges, rather than the more appropriate subset of sludges
reported to be landfilled. As shown in the previous table,
the median and maximum oil and grease values for landfilled
HF sludges are 1 and 3 percent, respectively. These lower
values reflect the common sense observations made earlier in
this section that high levels of hydrocarbons are often
reclaimed rather than disposed by the refining industry, and
perhaps more importantly, refineries generally do not
landfill materials with a measurable free oil or water
content due to restrictions on liquids in landfills.

Third, while EPA's sampling description of HF alkylation
sludge did indicate the presence of a liquid phase, three of
the five samples were collected from the settling portion of
the HF neutralization tanks. Standard refinery operating
practice for such sludges destined for landfilling is
centrifugation or filter press. However, due to
scheduling constraints EPA was not able to obtain these
samples after dewatering. Thus the use of these samples as
input to the groundwater model is conservative. With
respect to the remaining two HF sludge samples, EPA
collected these samples from the storage drums (no
dewatering occurred) for R9-HS-01 (31 percent oil and
grease) and after centrifugation for R7C-HS-01 (0.08 percent
oil and grease). The refineries reported in their 3007
surveys that these residuals were destined for a Subtitle C
landfill and a Subtitle D landfill, respectively, when
generated in 1992, although it is unclear whether these
practices were also used for the sludge samples collected in
May 1994 and October 1994, respectively.

Comment 8.e: EPA attempts to minimize the importance of the
high oil percentages found in the oily sludge samples by
noting in some cases they "appear" to represent oil levels
prior to deoiling, thereby suggesting the wastes actually
landfilled would have a substantially lower oil content. 
However, as the Agency previously noted, there is a wide
range of effectiveness of deoiling techniques between
refineries, and samples of deoiled wastes could contain more
oil than as generated wastes of the same type. Largely as a
result of these observations, the Agency determined that
differentiating between oily and de-oiled sediments was
inappropriate. Further, only about 30% of crude oil
storage tank sludge is even deoiled prior to final
management. No comparable percentages are provided for
other wastes. (EDF, 00006)

Response: With respect to data regarding the prevalence of
deoiling, EPA has previously published a report ("Waste
Minimization in the Petroleum Refining Industry," Docket F-
95-PRLP-S0064) and through the EPA's Internet server)
specifically discussing pollution prevention practices of
all residuals and wishes to correct the commenter's
statement that de-oiling frequency is only provided for
crude oil tank sediment. This waste minimization report
presents volume reduction techniques on a waste-by-waste
basis and states that based on the RCRA 3007 survey
responses, residual oil tank sludge, crude oil tank sludge,
and CSO tank sludge undergo volume reduction processes (such
as de-oiling) in approximately 23-32 percent of the cases,
depending on the specific waste.

Comment 8.f: Accordingly, contrary to EPA's assertions, the
extremely limited data in the NODA indicate the co-disposal
of oily wastes in refinery waste landfills is an actual or
potential mismanagement scenario, consistent with the
Agency's 1990 finding. Furthermore, since the NODA data
base is limited to wastes landfilled in 1992 that are
covered by this rulemaking or included in an accompanying
study, it does not account for other wastes codisposed in
refinery waste landfills. 

These other wastes fall into several categories. The first
category consists of wastes previously landfilled that are
now hazardous wastes, including the very F037-F038 wastes
EPA found to create cosolvent effects in 1990. Many
refinery waste landfills, both onsite and offsite, operate
for decades and contain numerous waste streams now
considered hazardous (including solvents and oily wastes)
that can facilitate the transport of contaminants in the
wastes covered by the instant rulemaking. Indeed, F037-
F038 wastes were legally disposed in nonhazardous refinery
waste landfills until May 2, 1991, just prior to the 1992
calendar year upon which EPA's data in the instant
rulemaking are based. Accordingly, if in 1990 EPA based its
regulatory decision making on cosolvency for F037-F038
wastes, there is no reason to depart from that approach in
the instant rulemaking because the same wastes are still
present in the same landfills.

The second category of other wastes includes nonhazardous
wastes that are landfilled but not covered by the instant
rulemaking or the accompanying study. These other wastes
represent a substantial portion of the waste codisposed with
the wastes at issue in this rulemaking. 

As illustrated in EDF's comments on the 1995 proposal,
refinery waste landfills are used for the broad array of
nonhazardous wastes generated at refinery sites, including
sludges and other wastes with a substantial oil component. 
For example, API reports that over 1.6 million metric tons
of refinery wastes were landfilled in 1992, most of which is
nonhazardous waste. 

The highest volume refinery waste landfilled in 1992,
according to API, was contaminated soils/solids, accounting
for almost 600,000 tons of landfilled waste. This
category includes "soil (crude) contaminated" and "soil
(product) contaminated". Given the extensive
environmental contamination at petroleum refineries from a
combination of crude oil spills, refined product spills, and
improper waste management, as previously documented by EPA
and further described elsewhere in these comments, much of
this contaminated soil and solids can be expected to contain
a substantial amount of oil. An additional 20,000 tons of
"other contaminated soils" which includes "oil spill debris,
waste oil absorbents, and tank bottom absorbents," were also
landfilled in 1992.

Other landfilled wastes containing oil and possibly solvents
include "other oily sludges and organic wastes". While only
9,922 metric tons of these wastes were landfilled in 1992,
the amount landfilled in 1993 mushroomed to 180,221 metric
tons, representing the second largest waste category
landfilled (after contaminated soils/solids) that year. 
This category of waste includes "PL pigging sludge, spent
additive (gasoline), and other organic sludges and
liquids".

As explained in Section II.E of these [EDF's] comments, both
EPA and API data demonstrate the importance of these other
wastes in an evaluation of a co-disposal scenario. On an
average basis, EPA data indicate 23,979 cubic meters of
onsite landfill capacity was used in 1992, well beyond the
annual median value of 2,170 cubic meters of co-disposal EPA
calculates for the wastes covered by this rulemaking and the
study wastes. Since most of the high volume wastes are
landfilled offsite, the effects of co-disposal offsite is
even greater for offsite disposal. 

The plausibility of the free-phased flow of contaminants
from a refinery waste management unit is further documented
in the accompanying Waterloo NAPL Report. Twenty-five
landfills receiving industrial wastes, and four waste
management facilities associated with the petroleum sector,
have either definitively caused DNAPL contamination of the
groundwater, or caused contamination with a high probability
of DNAPL based upon available indirect evidence. Refinery
wastes similar or identical to the wastes at issue in this
rulemaking, such as refinery tank bottom sludge, were
codisposed with other wastes in the units causing the DNAPL
contamination. 

Significantly, the authors also found DNAPL contamination
from waste management is a "national" problem associated
with many hydrogeological regions, and many types of waste
management units including landfills and surface
impoundments.

In summary, EPA's 1990 finding regarding the potential for
cosolvent effects from the variety of solvents and oils
disposed at refinery sites remains valid today. The oil
content of the wastes covered by this rulemaking and the
related study, and the oil and solvents contained in other
codisposed refinery wastes, can produce a free-phased flow
of contaminants in a refinery landfill under a plausible
mismanagement scenario. (EDF, 00006, pg 6)

Response: EPA has addressed the comments related to co-
disposal in Section I.A.3, and comments related to existing
contamination in Section I.A.6.g. In brief, EPA finds the
commenter's suggested expansions of the co-disposal scenario
are not appropriate. EPA believes that its core objective
in conducting this listing determination is to assess the
incremental risk associated with these materials. As such,
it is not appropriate to take into consideration pre-
existing contamination or co-disposal with residuals outside
of the scope of the consent decree. Such considerations are
better measures of the risk associated with landfills
containing the residuals of concern, rather than the
residuals themselves. 

EPA does not disagree that specific conditions at specific
landfills related to historical management of high oil
content materials may create a more aggressive mobility
scenario than that modeled in support of this rulemaking. 
However because the Listing Program is centered on waste-
specific determinations, rather than unit-specific
determinations, such scenarios are better controlled via
corrective action and the identification of these landfills
as solid waste management units (SWMUs).

In addition, EPA is making its listing determinations in the
range of a 10-5 to 10-6 risk threshold. This low threshold
is inherently conservative and is in keeping with the
thresholds set in the BIF rule which assumed that other
exposure routes had not been fully explored (hence the risk
threshold was not set at 10-4).

EPA also believes that the Agency's decision making data
base is sufficiently broad to address the types of
variability in waste characteristics of concern to the
commenter. As a result EPA does not believe it is necessary
to project additional variability via consideration of
further co-disposal scenarios. More specifically, EPA's
database is based on a full census of the refining industry,
capturing refining waste generations and management
practices for 1992. EPA has no reason to believe that 1992
is not representative of normal refinery operation and waste
practices. The industry is sufficiently large that, while
individual refineries may change their practices from year
to year (e.g., landfilling to land treatment), it is likely
that these shifts will be offset by other refineries making
the reverse changes (e.g., from land treatment to
landfilling). Further, EPA's use of Monte Carlo modeling
allows for the consideration of thousands of permutations of
possible modeling parameters, taking into account
variability at the 90th to 95th percentile. Consideration
of this variability did not drive the modeled risk to lower
levels.

Furthermore, the commenter argues that contaminated soils
codisposed with the residuals of concern are likely to
contain "a substantial amount of oil". The basis for this
conjecture is not on any hard data regarding actual
measurements, but on the commenter's concern with the
adequacy of the TCLP for oily wastes, the exemption from the
TC for petroleum-contaminated media from UST cleanups and
concerns regarding the implementability of the contained in
rule.

EPA evaluated the Waterloo report on ground-water
contamination. Given EPA's desire to assess the incremental
risk associated with the residuals of concern, EPA first
assessed whether this report provided any directly relevant
damage cases not previously identified by EPA. Among the 14
landfills and 27 surface impoundments characterized in this
report, none of these units were operated at petroleum
refineries. In addition, it appears that none of these
units were modeled as off-site landfills in support of the
listing determination. EPA also assessed the wastes and
toxicants reported to be managed in these units and was
unable to confirm EDF's conclusions that these units managed
any of the 29 refinery residuals of concern. Furthermore,
these materials are unlikely to generate DNAPL due to the
relative density of oil and water. The presence of benzene
and PAHs in these materials confirms the conclusions already
made by EPA with respect to it's own damage case assessment,
that these contaminants are difficult to link to specific
wastes or releases due to their commonness in refinery
materials (both product and residual), but can be linked to
environmental releases and damage cases.

Comment 9: Analysis of Leaching of Oily Waste

EPA correctly concludes that the residuals under
consideration do not have high levels of free oil. EPA
investigated the potential for release and migration of
residual constituents via multiphase transport. The Agency
modeled a high-end, worst case scenario using the residual
(Crude Oil Tank Sludge) with the highest fraction of oil
liquid. From the modeling results, EPA correctly concluded
that there is little or no expectation of significant
release of waste constituents via multiphase transport.
(EPA, 1995c) Therefore, EPA is justified in its decision
not to consider free oil in its risk assessment calculations
for the petroleum residuals in question. 

Further, EPA should also have a high level of confidence
that the estimates of contaminant leaching generated using
the TCLP are, if anything, conservative. API continues to
maintain that the TCLP likely overestimates contaminant
leaching. (Narquis, 1992) In addition, EPA's use of the
alternative OWEP on refining residuals, conducted in
response to comments, did not pose significantly different
results than the TCLP. (API, 00009)

Response: EPA acknowledges the commenter's input.

I.C.2. Potential for Additive Risks from Multiple Sources

Comment 1: Potential For Additive Risks from Multiple
Sources

In response to comments by EDF, EPA evaluated whether an
individual could be simultaneously exposed to waste
concentrations from both a LTU and a landfill. In
principle, API disagrees with the need to evaluate
cumulative risks from multiple wastes due to the
implausibility of the scenario. The results of EPA's
analysis confirms this position. Using site-specific data
for on-site facilities, EPA determined that simultaneous
exposure was not possible. The evidence evaluated by EPA
clearly supports the conclusion that there is a sufficient
distance between land disposal units and residential wells
and homes to prevent simultaneous exposure. (API, 00009, pg
24)

Response: EPA agrees with the commenter that the available
data indicate that simultaneous exposure to landfills and
land treatment units is unlikely.
