In This Issue:
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Comments on EPA Subsurface VI Guidance
due February 27, 2003 |
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EPA training seminars on draft
Subsurface VI Guidance |
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Johnson & Ettinger Model
status |
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New indoor air testing procedure
expected soon |
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New subslab vapor testing
procedure |
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EI Determinations can rely on JE
model |
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Vapor Intrusion regulation in
California |
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What's New? DTSC 1/28/03 guidance on
soil gas investigations |
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Featured Links:
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Comments on EPA Subsurface VI Guidance
due February 27, 2003
Comments on the OSWER Draft
Guidance for Evaluating the Vapor Intrusion to
Indoor Air Pathway from Groundwater and Soils
(Subsurface Vapor Intrusion Guidance), published
November 29, 2002 in the federal register (see
link below), are due on February 27, 2003.
Industry concerns were raised by John Quarles of
Morgan, Lewis & Bockius LLP at the EPA
seminars on the guidance in San Francisco and
Dallas (see next article), including the need to
proceed cautiously with this complex issue,
encouragement not to intrude on OSHA regulations
at industrial facilities, and concerns regarding
the availability of resources to deal with this
issue. The federal register notice and copies of
the draft guidance are available at:
EPA training seminars on draft
Subsurface VI Guidance
The last EPA training
seminar on the draft Subsurface Vapor Intrusion
Guidance will be held in Atlanta on February
25-26, 2003. Some additional space was recently
made available by moving to a larger room, so it
may still be possible to register at the link
below. Otherwise, the seminar presentations will
be posted on the internet at the same link in
April. Dave Folkes of EnviroGroup will be speaking
on the effectiveness of vapor intrusion mitigation
systems (see our website to download this
paper).
Johnson & Ettinger Model
status
The indoor air and soil vapor screening
levels presented in the draft Subsurface Vapor
Intrusion Guidance were developed using the
Johnson & Ettinger (1991) model. However, the
default parameters used for the guidance are
different, and more conservative, than the default
parameters used in the model currently posted on
the EPA Superfund website (see link below). We
understand that EPA is in the process of revising
the website version of the model to adopt the
default values used by the guidance, and that the
revised model will be posted soon. See Appendix G,
table G-3 of the draft VI guidance for a list of
the default values used in the guidance version of
the JE model. Contact us if you have any questions
about applying the JE model.
New indoor air testing procedure
expected soon
EPA is currently developing a supplement
to the TO-15, the standard summa canister
analytical method for collecting high quality
indoor air samples for VOC analyses, to
incorporate the high resolution tuning procedures
developed by the Colorado Department of Public
Health and Environment (CDPHE). The draft
protocol, called TO-15 Supplement, is currently in
the EPA clearance process and is expected to be
cleared in about 4 to 8 weeks. Meanwhile, the
CDPHE procedure may be downloaded at the following
website:
New subslab vapor testing
procedure
EPA is currently perfecting a method for
sampling subslab vapors utilizing TO-17. Subslab
vapor sampling is a key component of site-specific
vapor intrusion evaluations under the draft
Subsurface Vapor Intrusion Guidance (see first
article), and a potential way to avoid the
complications of background or indoor sources of
VOCs. The new subslab vapor testing method will be
based on TO-17. Both TO-17 and TO-15 are U. S. EPA
analytical methods for toxic organic compounds in
ambient air, included in the "Compendium of
Methods for the Determination of Toxic Organic
Compounds in Ambient Air - Second Edition", Office
of Research and Development, (EPA/625/R-96/010b).
TO-15 collects the sample in specially prepared
(SUMMA) canisters and utilizes high resolution gas
chromatography/mass spectrometry for analysis.
TO-17 utilizes a pump to draw an air sample onto
multi sorbent tubes. Thermal desorption is then
used to remove the VOCs and send them on to a
sample concentrator. The analytical technique is
the same as TO-15.
EI Determinations can rely on JE
model
Current Human Exposures Under Control
Environmental Indicators (EIs) do not require
confirmatory sampling (i.e., indoor air or subslab
vapor samples) to determine control, according to
the draft EPA Subsurface Vapor Intrusion Guidance
(p.38). In other words, site-specific modeling
using the Johnson & Ettinger model (see
earlier article) will generally be adequate to
determine whether the vapor intrusion pathway has
been controlled for EI purposes. EPA cautions that
indoor air or subslab vapor testing may be
required before approval of the final
remedy.
Vapor Intrusion regulation in
California
Each newsletter, we will try to provide
information and links on vapor intrusion
developments in different states. Not wanting to
take the easy way out, we are starting with
California. There are two groups of state agencies
which oversee hazardous waste/substance cleanups
in California:
I. The Department of Toxic
Substances Control (DTSC) is an agency of the
California Environmental Protection Agency and is
the authorized RCRA agency in California (see
Featured Links, upper left margin of newsletter).
It also operates the State Superfund Program, a
Voluntary Cleanup Program, conducts Brownfields
reuse related activities, and oversees cleanups at
military facilities. DTSC is currently developing
a comprehensive indoor air policy and also
regulations for indoor air sampling. DTSC does not
have generic soil screening numbers. It does have
a Preliminary Endangerment Assessment Guidance
Manual available at the link below. It also has
developed CalTOX, an automated spreadsheet which
is a total exposure model for contaminated soils
at hazardous waste sites. It addresses indoor
chemical vapors transferred from ground water and
soils utilizing the Johnson-Ettinger Model. CalTOX
can be found under Featured Links in the upper
left margin.
II. The State Water
Quality Control Board is an agency of the
California Environmental Protection Agency. This
agency has responsibility for underground and
above ground storage tank remediation. There are 9
regional water quality control boards under this
state agency. Some of these boards have developed
screening numbers for cleanups. The San Francisco
Bay Regional Water Quality Control Board, for
example, has risk based screening numbers at the
Featured Link in the upper left margin. That
regional board has also produced a December 24,
2002 a memo titled: "Interim Soil Gas Screening
Levels for Evaluation or Potential Indoor-Air
Impacts and Request for Comments". It includes
draft shallow soil gas screening levels for use in
evaluating potential indoor air impacts. This memo
can be reached from the Featured Link in the upper
left margin. Regional boards operate Spills,
Leaks, Investigation and Cleanup (SLIC) Programs
to address the effects of unauthorized discharges.
The regional boards sometimes delegate UST
cleanups to local governments.
What's New? DTSC 1/28/03 guidance on
soil gas investigations
On January 28, 2003 DTSC
released, jointly with the California Regional
Water Quality Control Board - Los Angeles Region,
a new guidance document "Advisory - Active Soil
Gas Investigations". It can be found at the link
below. It was developed to ensure that consistent
methodologies are used during soil gas
investigations.
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