vvEPA
United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
DIRECTIVE NUMBER: _93eo 1-01
TITLE: Interim Final Guidance on Removal Action Levels
at Contaminated Drinking water Sites
APPROVAL DATE: lo/oe/e?
EFFECTIVE DATE: lo/oe/s?
ORIGINATING OFFICE:
0 FINAL
of Solid Waste
D DRAFT
STATUS:
[ ] A- Pending OMB approval
{ j B- Pending AA-OSWER approval
[ ] C- For review &/or comment
[ ] D- In development or circulating
headquarters
REFERENCE (other documents):
OSWER OSWER OSWER
fE DIRECTIVE DIRECTIVE Di
-------
United States Environmental Protection Agency ,
Washington. DC 20460
OSWER Directive Initiation Request
1. Directive Number
9360.1-0-1
2. Originator Information
Name of Contact Person
Jean Schumann
Mail Code
WH-548/B
Office
OSWER/OERR/ERD
Telephone Code
382-4671
3. Title
Interim Final Guidance on Removal Action Levels at Contaminated Drinking
water Sites
4. Summary of Directive (induce brief statement of purpose)
Provides guidance to Regions on determining when to use removal authority to
provide alternate water supplies at contaminated drinking water sites.
5. Keywords Superf und, CERCLA, SARA rernoval action, alternate water supplies, drinking
^ water action levels
6a. Does This Directive Supersede Previous uirective(s)?
b. Does It Supplement Previous Directive(s)?
No
No
Yes What directive (number, title)
Yes What directive (number, title)
Pratt Level
A - Signed by AA/OAA
B - Signed by Office Director
D
C - For Review & Comment
0 - In Development
8. Document to be distributed to States by. Headquarters?
Yes
XX
No
This Request M««ts OSWER Directives System Format Standards.
9. Signatufe-ef-tea$Office Directives Qffordinaj
10. Name and Title or Apnrafi
Date
7
Oate
1 Ci/G.
EPA Form 1315-17 (R«v. 5-87) Previous
OSWER OSWER OSWER O
VE DIRECTIVE DIRECTIVE DIRECTIVE
-------
REMOVAL ACTION LEVELS FOR CONTAMINATED DRINKING WATER SITES
Introduction
The purpose of this guidance 1s to establish "action levels" for providing
alternate water supplies under Superfund removal authority at contanlnated
drinking water sites. The action level 1s the primary criterion that must be
met for a site to qualify for removal response. The action levels established
in this guidance must generally be satisfied before removal authority can be
used at either National Priorities List (NPL) sites or non-NPL sites.
Under the 1982 National Contingency Plan (NCP), removal actions were taken
in response to "Immediate and significant" threats to human health or the
environment. The removal program used the 10-Day Health Advisory as the principal
benchmark to identify those drinking water contamination Incidents that posed
the most acute threats to human health. The November 1985 NCP broadened removal
authority by authorizing response in situations that present a "threat" to
hu^an health or the environment. Therefore, removal actions may now be taken
in less urgent situations than under the 1982 NCP.
In response to this expansion of removal authority, the Office of Emergency
and Remedial Response (OERR) 1s revising removal program action levels for
contaminated drinking water sites. This guidance expands the previous policy
in a number of ways. First, the numeric action levels are now based on levels
that are protective for a lifetime exposure rather than a 10-day exposure.
Second, both carcinogenic and non-carcinogenic health effects are considered.
Third, a reduction factor is used for volatiles to account for exposure due to
Inhalation. Finally, additional guidance 1s provided on the use of site-specific
factors to trigger removal actions.
The action levels established in this guidance allow a site to qualify for
removal response 1f either: 1) the numeric trigger 1s exceeded at the tap, or
2) site-sped fie factors Otherwise Indicate that a significant health threat
exists. The guidance also discusses Information sources on health threats from
drinking water contamination, factors to consider in determining the extent of
action, action levels vs. cleanup standards, prioritizing removal sites, and
obtaining exemptions to the statutory limits for alternate water supply sites.
Action Level Based on Numeric Trigger
The numeric trigger 1s calculated using a model that establishes four
different action levels, depending on whether the substance 1s also a potential
human carcinogen and/or volatile. The model 1s explained below and summarized
1n Exhibit 1. Based on this model.Exhibit 2 lists the numeric action level
for various substances that may be found in drinking water at Superfund sites.
A site may qualify for removal response If the numeric trigger for the drinking
water contaminant 1s exceeded at the tap of at least one residence ("residence"
Includes schools, businesses, etc.). (Note that the decision to Initiate a
removal action Is based on other factors as well, such as the availability of
other response mechanisms to Initiate action In a timely manner.)
-------
-3-
the limited scope of the removal program, It may not be appropriate for
the removal program to trigger removal action at levels equal to or below
the MCL. Therefore, OERR is currently examining whether It would be
appropriate to establish an alternate action level for these substances
that 1s above the MCL. Until an action level is established for these
substances, removal action may be initiated if contaminant levels exceed
the 10-Day Health Advisory. However, 1f contaminant levels are between
the calculated action level and the 10-Day Health Advisory, OERR will review
individual site conditions to determine if removal action should be taken.
0 The calculated action level Is based on the DUEL, but the 10-Day Health
Advisory 1s lower than tne dwTTTFor most substances, the 10-Day Health
Advisory is higher than the DWEL. In some cases, however, the 10-day
advisory is lower than the DWEL. (This situation occurs primarily where
10-day exposure data were not available, so the 10-Day Health Advisories
were based on other studies.) For example, the action level for barium (a
non-volatile non-carcinogen) 1s based on the DWEL of 1800 ppb, but the 10-
Hay Health Advisory for barium is 1500 ppb. OERR is currently examining
whether it would be appropriate to use the lower 10-day advisories as the
removal action level. Until OERR determines 1f an alternate action level
1s appropriate for these substances, removal action may be Initiated 1f -
contaminant levels exceed the DWEL. However, if contaminant levels are
between the (lower) 10-Day Health Advisory and the DWEL, OERR will review
individual site conditions to determine if removal action should be taken.
Action Level Based on Site-Specific Factors
A significant health threat may exist even though the numeric action level
has not been exceeded. A removal action may be Initiated 1f the health risk at
a site has been analyzed in detail and the analysis indicates that a serious
health risk is present due to site-specific factors. Examples of such factors
include evidence that a contaminated groundwater plume 1s moving, contaminant
levels will likely Increase (e.g., increased pumping from an aquifer anticipated
during sunrner months), people have been drinking contaminated water for a long
period of time, multiple contaminants are likely to result In synergistic
effects, there are sensitive members In the population at risk, etc.
With regard to a threat based on future contamination, as a general rule,
removal action may be warranted where it can be projected that the numeric
action level will be exceeded within 6 months. It 1s Important to note that
this 6 month period 1s not related to the definition of time-critical/non-time-
critical removal actions. For example, where contaminant levels will Hkely
exceed the DUEL by a significant amount within. 6 months, a time-critical removal
action would be appropriate. However, 1f contaminant levels will only exceed
the DWEL by a minimal amount within 6 months, a non-time-critical removal
action may be more appropriate. Future threat may therefore warrant either a
time-critical or non-tlme-crltlcal removal action.
-------
-5-
Actlon Levels vs. Cleanup Standards
The numeric actfon levels established In this guidance are not Intended to
be used as cleanup standards. The MCL, 1f available, will general1 y be the
appropriate cleanup standard. (For guidance on the use of MCLs and MCLGs as
cleanup standards, see "Interim Guidance on Compliance with Applicable or
Relevant and Appropriate Requirements," July 9, 1987, OSWER Directive 9234.0-05.
Final guidance will be Issued 1n the CERCLA Compliance with ARARs Manual.)
This means that for any residence provided with an alternate water supply, the
goal will generally be to meet MCLs. For example, 1f carbon filter units
will be provided to treat drinking water contaminated with trlchloroethylene
(TCE), treated water should achieve 5 ppb TCE, the MCL.
Prioritizing Removal Sites
Sites may qualify for removal action under either the numeric Indicator or
site-specific factor approaches. For the purpose of prioritizing those sites
that qualify for removal action, response should be Initiated as soon as possible
1f contaminant levels exceed the 10-Day Health Advisory or site-specific factors
otherwise indicate that an emergency exists.
Exemption to the Statutory Limits " »
To obtain an exemption to the $2 mil 11 on/12 month limits on removal actions
based on a continuing emergency, 1t will generally not be adequate to show that
contaminant levels exceed the numeric action level by some minimal amount. An
exemption may be justified if contaminant levels exceed the 10-Day Health
Advisory, significantly exceed the numeric action level, or an emergency exists
based on site-specific factors. A finding that contaminant levels exceed the
numeric action level by a minimal amount may be appropriate, however, in
"non-emergency" situations where an exemption 1s based on the new consistency
waiver.
Summary of Policy
A contaminated drinking water site may qualify for removal response 1f:
1) the numeric action level (based on the DWEL and/or the 10*4 Lifetime
Upperbound Cancer Risk Level) Is exceeded, or 2) site-specific factors
otherwise indicate the presence of a serious health threat. In prioritizing
those sites that qualify for response under this model, Regions should
give priority to sites where contaminant levels exceed the 10-Day Health
Advisory or site-specific factors otherwise Indicate that an emergency
exists.
-------
Exhibit 1: Summary of Action Level Decision Model
Do contaminant levels "exceed the NUMERIC action level?
Is the substance a volatile and/or potential human carcinogen?
e Non-volatile non-carcinogens -- Action level equals the DUEL.
0 Volatile non-carcinogens — Action level equals 50% of the DWEL.
e Non-volatile carcinogens — Action level 1s determined by comparing the
DWEL to the 10'4 Lifetime Upperbound Cancer Risk Level, and choosing the
lower of the two.
0 Volatile carcinogens — Action level 1s determined by comparing 50% of the
OWEL to the 10'4 Lifetime Upperbound Cancer Risk Level, and choosing the
lower of the two.
Do either of the two modifications to the numeric action level apply?
Is the numeric action level lower than or equal to the MCL, 1f available? If yes:
~-\
0 If contaminant levels are between the numeric action level and the 10-Day
Health Advisory, contact OERR to determine appropriate action.
e If contaminant levels exceed the 10-Day Health Advisory, action may be taken
if the site otherwise qualifies for removal response.
If the action level 1s based on the DWEL, 1s the 10-Day Health Advisory lower
than the DWEL? If yes:
0 If contaminant levels.are between the (lower) 10-Day Health Advisory and the
DWEL, contact OERR to determine appropriate action.
8 If contaminant levels exceed the DWEL, action may be taken if the site
otherwise qualifies for removal response.
If contaminant levels do not exceed the numeric trigger, can the site qualify for
removal response based on SITE-SPECIFIC FACTORS?
A site can qualify for removal response if the health risk at a site has been
analyzed in detail and the analysis Indicates that a serious health risk 1s present
due to site-specific factors.
0 ATSDR may be particularly helpful In providing advice on health risk due to
site-specific factors.
0 OERR concurrence must be obtained before approving Action Memoranda based on
site-specific factors, even where the site will not exceed the statutory
limits on removal actions.
-------
FOR CONTAMINATED DRINKING WATER SITES
(ug/L)
Chemical
lachlor
arlum
?nzene
idmium
irbofuran
irbon tetrachlorlde
ilordane
il orobenzene
iromlum (total)
canide
•Dlchl orobenzene
-01 chl orobenzene
.2-01 chl oroethane
,1-Dlchloroethylene
is-l,2-Dichloroethylene
rans-1 ,2-Dl chl oroethyl ene
ichl orome thane/Methyl ene
chloride
Volatile
(Y/N)
N
N
Y
N
N
Y
N
Y
N
N
Y
Y
Y
Y
Y
Y
Y
EPA
Carcinogen
Groupa
B2
D
A
D
E
B2
D2
D
D
0
D
C
02
C
D
D
B2
MCL
None
1000
5
10
None
5
None
None
50
None
None
75
5
7
None
None
None
10- Day
HA
100
1500C
235
43C
5QC
160
63
4300C
1400
220C
8930C
10700C
74QC
1000C
100QC
1430C
• «••*
1500
DWELb
350
1800
NA
17
175
24
1.6
1505
168
770
3115
3500
None
350
350
350
1750
10-*
Cancer Risk
Level
.15
NA
120
NA
NA
27
2.7
NA
NA
NA
NA
175
38
None
NA
NA
48
Removal
Action
Level
15
iaood
120
17
175d
12
1.6
753
16H
770d
1558
175
3fl
175
175
175
48
-------
Mbit 2
KtnUKHL NUI1LNU, m.l»>;u Li.i4-i.-j
FOR CONTAMINATED DRINKING WATER SITES
(ug/L)
Chemical
Volatile
(Y/N)
EPA
Carcinogen
Group3
MCL
10- Day
HA
DWELb
10-4
Cancer Risk
Level
Removal
Action
Level
a Carcinogen group designation Is from EPA carcinogen classification guidelines for effects from ingestion.
b DUEL = RfD x 70 kg . (Note that the DWEL In health advisory documents produced by EPA's Office of Drinking Water
2 I/day may be slightly different due to rounding.)
c Because no suitable studies of appropriate duration Mere available, these 10-Day Health Advisories were based on
Health Advisories of greater or lesser duration, e.g., 1-Day, Longer-term, and Lifetime Health Advisories.
d Removal action level 1s an Interim value. OERR Is examining whether it would be appropriate to use the lower 10-Day
Health Advisory (50% for volatile*) as the action level. Until that time, If contaminant levels levels exceed the
action level shown in the table, removal action may be taken. If contaminant levels exceed the 10-day advisory
(501 for volatiles), but not the DWEL (501 for volatiles). consult OERR.
e Not soluble In water.
f Removal action may be Initiated if mercury levels exceed the DWEL of 5.5 ug/L. If mercury levels exceed the 10-day
advisory of 1.6 ug/L, but not 5.5 ug/L, consult OERR.
9 Removal action may be initiated immediately if toxaphene levels exceed the 10-Day Health Advisory of 40 ug/L.
If toxaphene levels exceed the 10-* Cancer Risk Level of 3.1 ug/L, but not 40 ug/L, consult OERR.
h Removal action may be initiated Immediately if vinyl chloride levels exceed 1300 ug/L, which is 50% of the 10-Day
Health Advisory. If vinyl chloride levels exceed the 10~4 Cancer Risk Level of 1.5 ug/1, but not 1300 ug/L.
consult OERR.
NA = Not appropriate.
------- |