&EPA
United States
Environmental Protection
Agency
Office of
Solid Waste And
Emergency Response
DIRECTIVE NUMBER: 9355.0-28
TITLE: Control of Air Emissions From Superlund Air Strippers
at Superlund Groundwater Sites
APPROVAL DATE: 06/15/89
EFFECTIVE DATE: 06/15/89
ORIGINATING OFFICE: OSWER/OERR/HSCD
0C FINAL
D DRAFT
STATUS:
REFERENCE (other documents):
OSWER OSWER OSWER
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UNITED STATES ENVIRONMENTAL PROTECTION AGEV
AASHiNGTCN DC 2C-J6C
JUM I 5 '.939
OSWER Directive 9355.0-28
MEMORANDUM
SUBJECT:
FROM:
Control of Air Emissions From Superfund Air
Strippers at Superfund Groundwatar Sites
TO:
Henry L. Longest II, Director
Office of Emergency and Remedi
Gerald Emison, Dir
Office of Air Quality 'plin
Addressees
nse
and Standards
PURPOSE
This memorandum establishes guidance on the control of air
emissions from air strippers used at Superfund sites for
groundwater treatment and establishes procedures for
implementation. Under this guidance, Regions should continue to
make air emission control decisions on a case-by-case basis
using the nine remedy selection criteria and the remedy
selection process set forth in the proposed National Contingency
Plan (NCP). As described below, however, the evaluation and
weighing of the criteria in a Mto be considered" (TBC) context
will differ according to the air quality status of the site's
location.
BACKGROUND
Approximately 35% of the Records of Decision (RODs) signed
to data have involved sites which use a pump and treat technique
to either partially or fully remediate groundwater
contamination. Close to 45% of these pump and treat sites have
selected air stripping. For the foreseeable future, OERR
expects to use air stripping at about the same rate. This
treatment technique relies on volatilization to remove volatile
organic compounds (VOCs) from the groundwater, i.e. it transfers
the contaminants from the liquid to vapor phase. One known side
effect of air stripping is the emission of VOCs, many of which
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are toxic, to the ambient air. The Superfund Program uses
control devices such as vapor phase carbon adsorption and
incineration to control these emissions.
In response to a request from Regional Air Division
Directors for a policy to guide the selection of controls for
air strippers, OERR and OAQPS conducted a joint study. The
results showed that historically close to half of the Superfund
air stripper sites had adopted controls during remedy
selection. Another 25 percent deferred the decision to the
remedial design phase. At sites with RODs signed after the
enactment of the Superfund Amendments and Reauthorization Act,
approximately two-thirds of the air strippers are controlled.
At these sites, control decisions were based on an analysis of
the cleanup standards established in Section 121 of CERCLA and
the other statutory considerations which together comprise the
nine remedy selection criteria: overall protection of human
health and the environment; compliance with Applicable or
Relevant and Appropriate Requirements (ARARs); long-term
effectiveness/permanence; reduction of mobility, toxicity or
volume (MTV); short-term effectiveness; implementability; cost;
State acceptance; and community acceptance. Control decisions
to date have been driven largely by protectiveness and State
ARARs for both air toxics control and VOC control for ozone
reduction. Other criteria such as MTV, short-term
effectiveness, cost, and community acceptance, have also
influenced the inclusion of controls.
Despite the trend towards increased control of air emissions
from Superfund air strippers, the Agency remains concerned with
the control of these air emissions. This concern underlies the
vigorous efforts by EPA, States, localities, and industry across
the country to control air toxics and reduce VOCs in ozone
nonattainment areas. The adoption of this policy responds to
these concerns, reflects an overall Agency concern with
preventing the cross-media transfer of pollutants, and
recognizes that the number of Federal, state, and local ARARs
for both VOCs and air toxics appears to be rapidly increasing.
The following policy has been adopted to guide Regional
decisionmaXers on the use of controls for air emissions from
Superfund air strippers, and other vented Superfund sources of
VOCs. This policy is grounded in the remedy selection process
and distinguishes between sites located in attainment and
nonattainment areas.
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STATEMENT OF POLICY
For sites located in areas that are attaining the National
Ambient Air Quality Standards for ozone, Regions should continue
applying controls based on existing Agency policy. In most
cases, this will mean the adoption of controls largely in
response to State ARARs, risk management (i.e., protective-
ness) guidelines, and other requirements of CERCLA Section 121.
In ozone nonattainment areas, however, the adoption of
controls is more likely to be indicated even if they are not •
mandated by current Federal or State laws and regulations or
indicated by a cancer risk analysis. Aside from cancer risk'
from air toxics, VOC emissions contribute to non-cancer health
risks in nonattainment areas because most are precursors to the
formation of ozone. Consideration of these non-cancer risks
when applying the remedy selection criteria generally will show
that in nonattainment areas Superfund air strippers, except
those with the lowest emissions rates as indicated below,
generally merit controls. In determining the need for air
stripper controls at a particular Superfund site in a
nonattainment area, the Regions should be guided by the
emissions limit goals in the document entitled, "Issues Relating
to VOC Regulation Cutpoints, Deficiencies, and Deviations,"
issued in May 1988 by the Office of Air Quality Planning and
Standards (OAQPS) to aid States in revising their State
Implementation Plans (SIPs) to incorporate post-1987 ozone
attainment strategies. The OAQPS guidance indicates that the
sources most in need of controls are those with an actual
emissions rate in excess of 3 pounds per hour (Ib/hr) or 15
Ib/day or a potential (i.e., calculated) rate of 10 tons per
year (TFY) of total VOCs. The calculated rate assumes 24-hour
operation, 365 days per year. Regions should note that control
levels are applied on a facility basis. For the purposes of
this guidance, facility is defined as a contiguous piece of
property under common ownership.
This guidance applies to air strippers at Superfund sites.
In establishing the policy, however, the potential for
applicability to other VOC sources is recognized. Generally,
the guidelines described for air strippers are suitable for VOC
air emissions from other vented extraction techniques (e.g.,
soil vapor extraction) but not from area sources (e.g., soil
excavation).
This guidance applies to future remedial decisions at
Superfund sites. The policy is not explicitly designed for
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actions taken by the removal program in the case of emergency or
time critical removal actions. However, where time and other
response circumstances permit, such as for non-time critical
actions, adherence to this policy is expected.
The control levels referred to above serve as guidelines
only if ARARs do not exist or are less stringent than presented
here. They are not intended to preclude or replace State
proposals for more stringent levels of control in pursuit of
Clean Air Act goals as part of SIP revisions in nonattainment
areas.
IMPLEMENTATION
This guidance seeks to incorporate air quality concerns into
the Superfund remedy selection process. In particular, the use
of controls for Superfund air strippers in nonattainment areas
demonstrates the Agency's commitment to reducing VOCs and thus
progressing toward attainment of the ozone standard.
Additionally, the guidance is consistent with both the current
NCP and proposed revisions. Where ARARs do not exist, EPA may
consider TBCs in setting target cleanup levels. This guidance
constitutes a TBC.
The Remedial Investigation/Feasibility Study (RI/FS) should
generate the data needed to support control decisions for both
attainment and nonattainment areas. At a minimum, the five
major types of information needed are:
Estimated cumulative uncontrolled air emissions rate
from all air strippers at the site
Consideration of health risks from the execution of the
remedy as well as from the uncontrolled site
Control alternatives and their costs
Ozone attainment status
Air ARARs
For purposes of this guidance "nonattainment area" means any
county included in a formal post-1987 ozone SIP deficiency
notification (SIP call) or any other county where the ozone
National Ambient Air Quality Standard was exceeded during the
previous three-year period. EPA's initial SIP calls were issued
pursuant to Section 110(a)(2)(H) of the Clean Air Act and were
described in the September 7, 1988 Federal Register.
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The RI/FS scoping phase and work plan development should
describe the specific data to be generated and the methods for
doing so. Remedial Project Managers should consult with the
designated Air Superfund Coordinator for technical assistance.
Additional assistance is available from National Technical
Guidance Manuals developed jointly by the Air and Superfund
program offices for estimating air emissions and conducting air
pathway analyses. The ROD should summarize this information as
appropriate and clearly document the basis for the air emissions
control decision.
Addressees:
Regional Waste Management Division Directors
Regional Superfund Branch Chiefs
Regional Air Division Directors
Regional Air Branch Chiefs
OERR Division Directors
OAQPS Division Directors
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REPORT DOCUMENTATION PAGE
Form Approved OMB No. 0704-0188
PB90-272667
2. Report Date:
06/15/89
3. Report Type And Dates Covered:
DIRECTIVE
4. Title And Subtitle: Control of Air Emissions
From Superfund Air Strippers at Superfund Groundw
ater Sites
6. Author(s):
5. Funding Numbers:
Performing Organization Names And Addresses:
Environmental Protection Agency
Office of Solid Waste and Emergency Response
401 M Street, SW
Washington, DC 20460
8. Performing Organization
Report Number:
EPA/9355.0-28
Sponsoring/Monitoring Agency Name(s)
And Address(es):
Environmental Protection Agency
Office of Emergency and Remedial Response
401 M Street, SW
Washington, DC 20460
10. Sponsoring/Monitoring
Agency Report Number:
11. Supplementary Notes:
12a. Distribution/Availability Statement:
12b. Distribution Code:
13. Abstract: .Establishes guidance on control of air emissions from air
strippers used at Superfund sites for groundwater treatraent. This joint
memorandum from Office Directors, OERR, and Air Quality Planning and Standar
ds, establishes procedures for implementation.-
14. Subject Terms:
SUPERFUND DOCUMENT:
Remedial
15. Number Of Pages:
8
16. Price Code: A02
17. Report Security
Classication:
18. Page Security
Classication:
19. Abstract Security
Classication:
20. Media:
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