vvEPA
United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
DIRECTIVE NUMBER: 948i.13(84)
TITLE: Establishing Alternate Concentration Limits (ACLs)
' . for RCRA Permits .......
APPROVAL DATE: n-19-84
EFFECTIVE DATE: n-19-84
ORIGINATING OFFICE: office of Solid "waste
0 FINAL
D DRAFT
-C :I ~ PeninS OMB "approval '••'
,[ ] B-; Pending 'AA-OSWER approval-^
'[ ]. ..C-.;For-ireyiew_.&/or- comment :-^--^
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PARTS 264 AND 265 SUBPART F - GROUND-WATER PROTECTION DOC: 9481.13(84)
Key Words: Alternate Concentration Limit (ACL), Risk, RCRA Permits
Regulations: 40 CFR 264.94(b) .
Subject: Establishing Alternate Concentration Limits (ACLs) for RCRA
Permits
Addressee: Morris Kay, Regional Administrator, Region VII
Originator: Lee M. Thomas, Assistant Administrator
Source Doc: #9481.13(84)
Date: 11-19-84
Summary:
An ACL demonstration must justify all claims regarding the potential effects
of ground—water contaminants on human health and the environment. This process
requires risk analysis and risk management. In terras of human considerations,-
the regulations require assessments of toxicity, exposure pathways, and exposed
populations.
To obtain an ACL, a permit applicant must demonstrate: a) that there will
be no exposure, or b) that the exposure will be at levels which do not pose a
substantial threat to human health and the environment. In the latter case,
the applicant must distinguish between ground-water contaminants having threshold
(toxic) and nonthreshold (carcinogenic) effects. Acceptable exposure levels
for threshold contaminants can be derived from acceptable daily intakes (ADIs).
The acceptable concentration of non-threshold compounds or carcinogens is
determined through the risk management process. In general, the Agency allows
concentrations of carcinogens where the individual risk values are within the
10~^ to 10~° range. Acceptable risk levels to any exposed individual within
the 10"^ to 10~° range. Acceptable risk levels to any exposed individual within
the 10"^ to 10~° range must be established on a site-by-site basi-s, taking
into account various factors.
In general, permit writers should encourage owners and operators to consider
a level of 10~° to be used as a point of departure when proposing a risk level
within the 10~4 to ICT8 range for their particular facility.
ACLs are established at the waste management boundary point of compliance.
The risk levels are determined at the designated point of use. The designated
point of use where potential exposure may occur is at any point downgradient of
the property boundary, unless there are controls beyond the present boundary
that will prevent use of the affected resource.
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MEMORANDUM
WASHINGTON. D.C. 20460
9 :?3
9481.13 (84!
SOl-iQ WASTE ANO EMERGENCY B6SPQNSE
SUBJECT: International Pa/pkr ACI—JDemonstrat ion
FROM:
TO:
Lee M. Thomas
Assistant Administrator
Morris Kay
Regional Administrator
Region VII
This memo is in response to a request from David Wagoner
to John Skinner for guidance concerning the setting of accepta-le
risk levels for carcinogenic constituents in establishing
alternate concentration limits.
Alternate concentration limits (ACLs) can be established
for hazardous constituents identified in the ground water if
the constituent will not pose a substantial -resent or potential
hazard to h-man he-alth or the environment as Long as the limit
is not exceeded at the edge of the waste mar. = ~e~.ent area.
This process involves risk analysis and risk management. The
ACL demonstration must justify all claims retarding the potential
effects of ground water contaminants on human health and the
environment. In terms of human considerations, the regulations
require assessments of toxicity, exposure pat-ways, and exposed
populations. The relevant factors listed in J254.94(b) include:
*_ physical and chemical characteristics of the waste
0 hydrogeolcgica1 characteristics cf the sice
0 ground water flow rate and direction
9 proximity and withdrawal rates of grcjnd water users
0 proximity of surface waters to the site
0 current and future uses of ground water in the area
0 current and future uses of surface waters in the area and
any applicable standards
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0 potential health risks of each waste constituent
0 persistence and permanence of potential adverse effects.
There are two approaches open to an owner or operator of a «*
facility to make the necessary ACL demonstration:
(1) that there will be no exposure, or
(2) that the exposure will be at levels which do not
pose a substantial threat to human health and the
environment.
In the second approach, the permit applicant must distinguish
between ground water contaminants having threshold (toxic) and
non-threshold (carcinogenic) effects. Acceptable exposure levels
for threshold contaminants can be derived from acceptable daily
intakes (ADIs). Draft guidance on the usa of ADIs has been
published by the Agency (Guidance and Methods for the use of
Acceptable Daily Intakes in Health Risk Assessment, U.S. EPA, .
1934). The acceptable concentration of non-threshold compounds,
or carcinogens, is determined through the risk management process.
Several contaminants in Appendix VIII have unit cancer risk
(UCR) values associated with them. The UCR values are used to
estimate water concentrations that correspond to lifetime statistical
cancer risk values. The lifetime statistical cancer risk value
must be chosen during the risk management process. In general,
the Age_ncy has made decisions to allow concentrations of carcinogens
where the individual risk values have been within the range of
1CT4 to 10"a.
For setting ACLs for RCRA permits you should consider, the
following factors in determining an acceptable risk level to any
exposed individual within the 10~4 to 10~3 range:
(1). .other environmental health factors iorne by
the affected population, i.e., are they already
exposed to known air, water, or other pollutants
such that they have a high risk loa-J.;
(2) level of uncertainty in the data base ar.d models
used in the risk analysis;
(3) expected effectiveness and reliaoility of man-made
systems affecting exposure (e.g., slurry walls, pumping
wells, and the likelihood that off-site wells will alter
ground-water flow patterns);
(4) current and expected future use of the affected
resource;
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(5) impacts upon the environment (i.e., receiving ecosystem)
ac any surface water to which the plume will discharge.
It is-generally useful to also determine the total population
that is currently exposed or lively to be exposed in the future,
and the cost or cost effectiveness of the corrective action or •*
engineered solution. These considerations may be useful for public
hearings and for weighing the importance of the five factors.
Many of the factors that are critical to setting ACLs are site
specific. Therefore, acceptable individual risk levels for
non-threshold compounds must be established on a site-by-site
basis. When applying these risk management factors to an ACL
demonstration, both the current and potential impacts must be
considered. It is also necessary to consider the above factors
in the context of the §254.94(b) criteria.
The site conditions at the International Paper (I?) facility
in Joplin, Missouri, are similar to the Reilly Tar Superfund Site
in St. Louis Park, Minnesota. Both facilities were wood preserving
plants that operated for -lore than 50 years. The facilities
used a creosote preserving process. The chemical compounds
associated with this process are polynuclear aromatic hydrocarbons
(PAH) and phenolics. Many of the PAHs are potent carcinogens.
At both sites, PAHs have entered shallow aquifers. The subsurface
geology at both sites is such that movement of contaminants can
occur without significant attenuation. The drinking water aquifer
at the Reilly Tar site is contaminated and the drinking water
aquifer at the I? facility is threatened.
On June 6, 1984, I signed the Record of-Decision for the
Reilly Tar Pits Superfund Site. In this decision, I selected a
remedy that allowed a ris'< level of 10"^ (one chance in a million)
in determining acceptable concentrations of carcinogenic compounds
in water used as drinking water. In this case the concentration
level, in the absence of any applicable standards, was selected
on the judgement that-it was effective in protecting human health
and could reasonably be implemented. In the I? case, consideration
of the five factors outlined above may support a different risk
level (higher or lower) as providing an acceptable level of
protection to human health. However, in the I? case, serious
consideration should be given-to the 1Q~^ ris<; level because
of the similarity between the two sites and the need for consistency
under similar circumstances. As a general matter, I recommend
that permit writers encourage owners and operators to consider a
level of 10"°, the middle of the range, to be used as the
point of departure when proposing a risk level within the 10~4
to 10~3 range for their particular facility.
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ACLs are established ac the waste managemenc boundary
of compliance). The risk levels are determined at the d£.= •-.7-2.^.ed
point of use. The allowable concentration of carcinogen:.; compound
at the designated point of use would not be expected to '2-5 -exceeded
as long as the ACL at the compliance point is not exceedii, T'la
designated point of use where potential exposure may occ-ir is at
any point downgradient of the property boundary, unless t'iwrs
are controls beyond the present boundary that will prever.t U£S-*i
of the affected resource (e.g., State or local controls, or
restrictions). Since no such controls are in place at I"**
potential exposure point is at or within IP's property iou-ii
In order to designate the property boundary as the point -•£
exposure, I? must ensure that there are permanent prohii L~z~
on the use of on-site ground water as a source o£ drinka-t;;
or for any other use that would not be protective of huiran-
and the environment. These restrictions must apply to 1?
it retains ownership for the site, as well as to any succ^-
in interest.
cc: Jack McGraw
Marjorie Russell
Merrill S. Hohman
Conrad Simon
Stephen R. Wassarsug
David Wagoner
Tom Devine
Bill Constantelos
Aliyn M. Davis
Robert L. Duprey
Harry Seraydarian
Charles E. Findlev
OSW Senior Staff
Lisa Friedman
Mark Greenwood
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION VII
324 EAST ELEVENTH STREET
KANSAS CITY. MISSOURI - 641C6
MEMORANDUM
SUBJECT: Final Response oa ACLs for International Paper Company,
Joplin, Missouri
' /'
FROM: David A. Wagoner /'/;, , /
•Director, Air and Waste'^wn-a^omeri't-Division, Region VII
TO: John H. Skinner (WH-5523)
Director, Office of Solid Waste
You and I have previously discussed the alternate concentration limits
(ACL) proposed by International Paper Company (IP) for their Joplin, Missouri
facility. I? has proposed to use amoient health criteria (human toxicity
values or 10~5 cancer risk level's) as their alternate concentration limits
at the point of compliance. Attached is the portion of our response letter
which covers tne ACL issue.
We plan to approve the proposed ACL for oenzo(a)pyrene based on the
10~5 criteria. We also plan to reduce the proposed ACL for pentachlorophenol
from tne toxicity criteria of 1.01 mc/1 to the estimated organoleptic level
of 30 ug/1, since values above 30 ug/i would rende- :ne groundwater unsuitable
for driruing.
If you disagree with eitne- of these approacr-js, please let us know by
COB F'-iaay, Octooer 5, 1934. Ue plan to transmit o--- comments by that date
unless we hear from you. Please call 3ob Stewart o'- Lynn Harrington at
753-6531, or myself at 753-6529.
Attachment
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Alternate Concentration Limits
33. We agree that you have followed generally appropriate methodologies
in preparing the Acceptable exposure Levels in the May 1984 Supplement.
We also agree with the ACL value proposed for benzo(a)pyrene of 0.023 ug/1.
However, we feel that the organoleptic level of 30 ug/1 snould be the ACL
for pentachlorophenol, since concentrations in the groundwater at that
level could prohibit the use of the supply for drinking water.
You snould now proceed to prepare proposed ACLs for the remainder of
the Appendix VIII compounds identified in the groundwater or sludge. We
will expect to receive these proposals by Oecemoer 14, 1984.
34. There appear to be typos on pages 32 and 50 of the Supplement for
the no effect level for benzo(a}pyrene. Based on othe.'' pages and tables,
the correct level would be 0.028 ug/1, not mg/1. In addition, 3aP does
not have a calculated no effect thresnold. The published EPA criterion in
ambient water of .028 ug/1 is associated with an excess, lifetime cancer
risx of 10-3.
35. You should also consider dermal contact and aquatic life effects due
to the springs, seeps and creeks soutnwest of the site. Concentrations
snould be specified for tne discussion on page 48 concerning dermal effects,
36. There appears to be an error in Table 3, page 13 of Appendix A. Fo1"
tne ratio of tumors to rats witn tumors, control males snould be 1.0.
37. The Table 2 referenced on page 17 of Appendix A :$ missing.
38. The first 2 sentences of section 5.1 are correct. We know of no
published methodology, however, that could be used to estimate a criterion
for 3aP based on snort term subcutaneous aosing. We suggest that this
calculation be deleted.
39. You should reference the last statement on page 3-i.
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