In This Issue:
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What Is The Toxicity of
PCE? |
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EPA Johnson and Ettinger Model Website
Has Been Updated |
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Michigan DEQ’s Approach to Vapor
Intrusion |
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Pennsylvania Vapor Intrusion Draft
Guidance |
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Proposed Changes to Connecticut
Volatilization Criteria |
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GRA Vapor Intrusion
Symposium |
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RCRA National Meeting |
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EnviroGroup Boston
Office |
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Featured Links:
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What Is The Toxicity of PCE?
The toxicity of PCE or
tetrachloroethylene, a common groundwater and
vapor intrusion compound of concern, is the
subject of significant controversy. Resultant
vapor intrusion “action levels” vary between
agencies and will likely vary over time. Click on
the following link for a brief overview of the
current status of PCE toxicity, particularly as it
relates to vapor intrusion.
EPA Johnson and Ettinger Model Website
Has Been Updated
The Johnson and Ettinger models on the EPA
Superfund web site have been updated to now
incorporate the default values recommended in the
OSWER Draft Guidance for Evaluating the Vapor
Intrusion for Evaluating the Vapor intrusion to
Indoor Air Pathway (November 2002). The default
parameters include both building related and soil
type related numbers designed to provide a
reasonably conservative assessment. Building
related parameters include estimates such as air
exchange rates, footprint area, perimeter crack
width, and crack ratios. Soil related parameters
include moisture content for both the unsaturated
and capillary transition zones. These models can
be found at:
Michigan DEQ’s Approach to Vapor
Intrusion
Michigan’s environmental remediation
requirements are derived from Part 201 of the
Natural Resources and Environmental Protection
Act. The rules implementing this section of the
law can be found at the first "featured link" in
the left column of this newsletter (or at the
bottom, if you are viewing a text version of the
newsletter).
Rule 714 explains the basis
for the generic criteria for groundwater based on
hazardous substance vapors emanating from
groundwater to indoor air. Likewise Rule 724
explains the generic cleanup criteria for soil
based on volatilization to indoor air. Clicking on
the second link in the left column will provide
you with three generic cleanup tables.
The
Rule 744 table is Table 1 providing the generic
groundwater cleanup criteria including
volatilization criteria for two land use classes.
The Rule 746 table is Table 2 providing the
generic soil cleanup criteria for residential and
some commercial land uses including the
volatilization criteria. The Rule 748 table is
Table 3, which provides similar soil cleanup
criteria for industrial and other commercial land
uses. The Rule 750 table includes the footnotes
which help explain the other three
tables.
Two key vapor intrusion documents
can also be accessed through the third link in the
column to the left. Under “Information”, click on
the second listing: Part 201/213 Acceptable Indoor
Air Concentrations. This will bring you to a seven
page table of acceptable air contaminants for both
residential and industrial and commercial land
uses. Under “Part 201 Operational Memoranda and
Guidance” click on: Technical Support Documents
for Op Memo # 18. Then click on: Generic
Groundwater and Soil Volatilization to Indoor Air
Inhalation Criteria. This will bring you to the
1998 Technical Support Document, which explains in
detail how the groundwater and soil volatilization
criteria were developed. This document is
currently being updated and will include guidance
for collecting soil gas and indoor air samples as
an alternative means (from the generic screening
criteria) for assessing the indoor air
pathway.
Links for a variety of other state
vapor intrusion programs can be found at the
following link. New states are added all the time,
so check back later if the state you are
interested in is not shown.
Pennsylvania Vapor Intrusion Draft
Guidance
The Pennsylvania Department of
Environmental Protection is in the final stages of
developing detailed vapor intrusion guidance to be
incorporated into its Technical Guidance Manual
for the Land Recycling Program under the Act 2
legislation. The guidance will be presented to the
Cleanup Standards Scientific Advisory Board July
22 for approval and the anticipated effective date
is October 26, 2003. The guidance will fit under
the statewide health standard of the Land
Recycling Program. The guidance includes nine
tables of screening numbers for ground water,
soil, and indoor air considering aquifers which
are both used and not used for drinking water and
for residential and commercial/industrial land
uses. The tables were calculated using a cancer
risk of 10 -5. Evaluation of this pathway is
necessary when an inhabited building is located
within 100 feet of a source of groundwater plume
containing volatile compounds. Although this
document is not a regulation it establishes the
framework within which DEP will exercise its
administrative discretion in the future. The draft
guidance can be found at (click on the items under
the June 11, 2003 heading):
Proposed Changes to Connecticut
Volatilization Criteria
In March 2003 Connecticut
proposed changes to its volatilization criteria
and is accepting comments until June 30, 2003.
Connecticut was one of the first states in the
country to directly address this pathway of
exposure and has had volatilization criteria from
at least 1996. The changes include the updated
Johnson Ettinger model considering both diffusion
and advection, updated target air concentrations
based on current toxicity information and
background levels, application of the criteria to
ground water within 30 feet of the surface (as
opposed to 15 feet), less stringent criteria for
industrial/commercial land use, and special
attention to the potential exposures of children.
Background data from several sources has been
examined and used to set the target air
concentrations for substances where the risk based
calculated numbers would have been below
background (TCE, PCE, benzene). The target air
concentrations for vinyl chloride and 1,1-DCE have
been made less restrictive and the target air
concentration for TCE has been made more
restrictive. The proposed changes can be found
at:
GRA Vapor Intrusion
Symposium
The Groundwater Resources Association
(GRA) of California is sponsoring a symposium on
Subsurface Vapor Intrusion to Indoor Air on
September 30 and October 1, 2003 in San Jose and
Long Beach CA, respectively. The one day seminar
includes presentations on California's perspective
on vapor intrusion issues, collection of field
data, predictive modeling, background
concentrations, and engineering controls. Speakers
include DTSC, EPA, and San Francisco RWQCB
experts, as well as Paul Johnson and Robbie
Ettinger. Click on the following link for more
information.
RCRA National Meeting
This year's RCRA National
Meeting, to be held in Washington D.C. August
12-15, 2003, will feature special sessions on
vapor intrusion. Click on the following link for
more information.
EnviroGroup Boston Office
EnviroGroup is pleased to
announce the opening of its Boston office as of
July 2003. Although EnviroGroup has always
provided clients with expert environmental and
vapor intrusion services across North America, our
Boston office allows us to provide more rapid and
cost effective services in the northeast. Click
below for more information:
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