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. ------- |