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

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           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

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          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.)

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                                       -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.

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                                   -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.

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            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.

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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

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 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.

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