What's New for the SRP Vapor Intrusion Guidance Documents
Revisions to indoor air and sub slab soil gas sampling requirements at vapor intrusion investigations.
Posted 17 November 2009
As previously stated, the NJDEP is currently preparing a revised Vapor Intrusion Guidance document that will likely include numerous modifications to procedures for investigating and mitigating the vapor intrusion (VI) pathway. A draft copy of the revised document should be available for external review and comment shortly.
In August 2009, the Department implemented a procedural change that dealt with the concurrent collection of sub-slab soil gas and indoor air samples at buildings with sensitive populations. While the intention was to expedite VI investigations for people at potentially greater risk, the procedure created unseen technical problems that warranted further evaluation prior to implementation. Therefore, the policy has been modified.
As it relates to all building interior investigations of the VI pathway, the investigator has three options.
Option 1) The current NJDEP Vapor Intrusion Guidance recommends that exceedance of the Ground Water Screening Levels triggers the collection of sub-slab soil gas samples. Then, if the Soil Gas Screening Levels are exceeded, indoor air samples shall be collected. The Investigator may continue to follow this approach.
Option 2) The Investigator can collect both sub-slab soil gas and indoor air concurrently upon the initial trigger (as stipulated in N.J.A.C. 7:26E-1.18) of a vapor intrusion investigation. The sub-slab soil gas and indoor air samples will be submitted to the certified lab for analysis.
Option 3) The Investigator can collect both sub-slab soil gas and indoor air concurrently upon the initial trigger (as stipulated in N.J.A.C. 7:26E-1.18) of a vapor intrusion investigation. The sub-slab soil gas and indoor air samples will be submitted to the certified lab for analysis. However, only the sub-slab soil gas samples are initially analyzed. Assuming that holding times are met, the indoor air samples would only be analyzed if the sub-slab soil gas results exceed the Soil Gas Screening Levels.
For either option 2 or 3, the indoor air sample shall be collected first at the structure undergoing investigation. This provision is designed to avoid the potential for cross-contamination between the soil gas and indoor air. Once the indoor air sampling is completed, the investigator shall immediately collect the sub-slab soil gas sample. Using the typical 24-hour sampling timeframe, the indoor air sample shall be sampled on Day 1. Twenty four (24) hours later (Day 2), the indoor air sample canister is closed and the investigator shall drill the sample port and collect the sub-slab soil gas sample (usually 5-30 minutes).
This policy change should be implemented immediately.
Update History
2009
Change in indoor air and sub slab soil gas sampling requirements at vapor intrusion investigations involving sensitive populations.
Posted 21 August 2009
A number of changes related to vapor intrusion are in various stages of development and implementation. The NJDEP Vapor Intrusion Guidance document is currently undergoing major revisions. It is the Department’s intent to issue a revised document by the end of 2009.
One change that is being implemented now deals with the investigative approach to vapor intrusion. Specifically, sub-slab soil gas and indoor air samples shall be collected concurrently for all buildings having sensitive populations. The Department considers sensitive uses to include, but not limited to, child care centers, schools, and residential properties.
As currently written, the Vapor Intrusion Guidance recommends that exceedances of the Ground Water Screening Levels triggering the collection of sub-slab soil gas samples. Then, if the Soil Gas Screening Levels are exceeded, indoor air samples shall be collected. The new change in policy will require the collection of both sub-slab soil gas and indoor air upon the initial trigger (usually an exceedance of a Ground Water Screening Level) of a vapor intrusion investigation.
To avoid the potential for cross-contamination between the soil gas and indoor air, the indoor air sample shall be collected first at the structure undergoing investigation. Once the indoor air sampling is completed, the investigator shall immediately collect the sub-slab soil gas sample. Using the typical 24-hour sampling timeframe, the indoor air sample shall be sampled on Day 1. Twenty four (24) hours later (Day 2), the indoor air sample canister is closed and the investigator shall drill the sample port and collect the sub-slab soil gas sample.
This policy change should be implemented immediately.
Revised NJDEP Low Level Method TO-15 and the associated deliverable requirements, (NJDEP LL TO-15 Appendix)
Posted 14 April 2009
NJDEP Low Level Method TO-15 and the associated deliverable requirements, (NJDEP LL TO-15 Appendix) have been revised and the updates have been added to the Web site.
2008
New FAQ and updated fact sheets
Posted 28 November 2008
A new Frequently Asked Questions (FAQ) section and updated versions of the Evaluating Indoor Air Near VOC Contaminated Sites and Subsurface Depressurization Systems fact sheets have been added to the Web site.
2007
Updated Web Address in the Vapor Intrusion Guidance
document
Posted 7 December 2007
Page 139 of the Vapor Intrusion Guidance (vig_main.pdf) has been updated.
The Web address (URL) for the USEPA's document Building Radon Out: A
Step-by-Step Guide on how to build Radon-Resistant Homes has changed.
Old URL: http://www.epa.gov/iaq/radon/images/buildradonout.pdf
New URL: http://www.epa.gov/radon/pdfs/buildradonout.pdf
Status of the New NJDEP Low Level Method TO-15
(NJDEP-LLTO-15)
Posted 21 November 2007
The laboratory certification process for the new
NJDEP Low Level Method TO-15 air analytical method for volatile
organics is currently in progress. As more laboratories are certified,
the Department will require all Method TO-15 analyses to be conducted
using the new NJDEP low level air analytical method. A notice will be
posted on this web site when the required change to the new method will
be in effect. It is recommended that interested parties periodically
check this web site for additional updates on this issue.
Important Notice Concerning the "Low Level
Air Analysis Method ("New Method"; LLTO-15)"
Posted 19 June 2007
The Site Remediation Program will not be changing to the new "NJDEP-SRWM
Low Level USEPA Method TO-15 (NJDEP- LLTO-15)" on July 1, 2007.
The change will occur during the summer of 2007. A notice will be posted
on this Web site when the change to the new method will be effective.
At the same time the new NJDEP Screening levels will be posted that
reflect the new method requirements. Please check this Web site for
any additional updates on this issue.
Screening Level Tables Update
Posted 28 March 2007.
The NJDEP has modified the May 2006 screening level tables for the Vapor
Intrusion Guidance (VIG) document based on new toxicity factor information
included in the latest (10/31/2006) USEPA Region III Risk Based Concentration
(RBC) Table. The revised tables (dated March 2007) may be accessed at:
http://www.nj.gov/dep/srp/guidance/vaporintrusion/vig_tables.pdf.
[pdf 846 Kb] The updated screening levels
and associated toxicity factor information have been highlighted in the
applicable tables with a double asterisk.
Note the tables are also available in Excel spreadsheet format:
The toxicity factor changes included in the latest USEPA Region III RBC
Table result in the inclusion of one additional chemical, 1,2 dichloroethene
(cis), to the previous May 2006 VIG Tables. The contaminant’s inclusion
in the updated tables is based on the availability of a current USEPA
Provisional Peer Reviewed Toxicity Value (PPRTV) for the chemical. It
should be noted that the PPRTV oral reference dose (RfD) and resulting
screening levels for 1,2 dichloroethene (cis) were reevaluated and determined
to be the same as the values that were previously presented in the Department’s
October 2005 VIG Tables.
The Department has also added Indoor Air Screening Levels (IASL) for
elemental mercury to the VIG tables (see Tables 1 and G-4). The health-based
values have been calculated as discussed in Appendix G of the VIG using
the current USEPA Region III/IRIS toxicity factor. Generic reporting limit
values have not been included in the applicable tables since the reporting
limit attained in the analysis for elemental mercury is based on collection
specific factors. The Department currently recommends the use of NIOSH
Method 6009 when collecting indoor air samples for elemental mercury with
attempts to attain a reporting limit as close as possible to the noted
health-based values. The laboratory, in consultation with the environmental
consultant, must submit their reporting limit prior to sampling. Other
methods can be proposed to the Department.
The Table 2 indoor air Health Department Notification Levels (HDNL) for
benzene and xylenes have also been updated to reflect the latest ATSDR
acute Minimum Risk Levels (MRL) for the two parameters. The latest acute
MRL for benzene of 9 ppbv has resulted in a decrease in the resulting
HDNL, while the latest acute MRL for xylenes of 2,000 ppbv has resulted
in an increase in the resulting HDNL. The Rapid Action Level (RAL) for
benzene has been set at the updated HDNL, which is lower than the RAL
as determined using the criteria outlined in footnote “c”
of the table.
New Analytical Method for Volatile Organics in
Air NJDEP-LLTO-15- 3/2007
Unless otherwise indicated, posted 28 March 2007.
The issuance of this new method is the first step in the formal progression
to lower the reporting limits for the majority of the volatile organics
required by NJDEP. This will move the reporting limits for some compounds
closer to the health based criteria.
2006
Screening Level Updates
Posted June 2006.
The NJDEP has modified the March 2006 screening level
tables for the Vapor Intrusion Guidance (VIG) document based on new toxicity
factor information included in the latest (4/7/2006) USEPA Region III
Risk Based Concentration (RBC) Table. The updated screening levels and
associated toxicity factor information have been highlighted in the applicable
tables with a double asterisk.
The toxicity factor changes included in the latest USEPA
Region III RBC Table result in modifications to the NJDEP screening levels
for four of the listed chemicals presented in the previous March 2006
VIG Tables. The four chemicals include chlorobenzene, 1,2-dichloroethene
(trans), n-hexane and 1,2,4-trichlorobenzene. A toxicity factor change
to the chemical, 1,2-dichloroethane, included in the Region III RBC Table
does not result in modification of the chemical’s screening levels
in the NJDEP VIG Tables since the toxicity factor change does not affect
the inhalation based toxicity information used to develop the screening
levels.
As a result of the new toxicity information, the ground
water, soil gas and indoor air screening levels for the four chemicals
noted above have been modified in the latest May 2006 NJDEP VIG Tables.
The screening levels for 1,2-dichloroethene (trans) and 1,2,4-trichlorobenzene
have increased, while the screening levels for chlorobenzene have decreased.
The screening levels for n-hexane have also increased except for the generic
Ground Water Screening Level (GWSL) and the loamy-sand based Alternate
Soil Texture GWSL that have remained the same. These values (presented
in Tables 1, 3 and G-1) are unchanged since the calculated ground water
to indoor air values continue to default to the higher Ground Water Quality
Standard.
New Jersey Version of the USEPA
Johnson and Ettinger (J&E) Model Spreadsheets
Updated NJDEP-modified J&E model spreadsheets have
been added to the web site based on the latest USEPA Region III toxicity
factor changes and the latest version (3.1) of the J&E model spreadsheets.
The instructions for the use of the model spreadsheets have also been
modified to clarify that version 3.1, rather than version 3.0, of the
USEPA J&E spreadsheets have been used by the Department.
The latest NJDEP-modified J&E model spreadsheets
and instructions on their use may be accessed at http://www.nj.gov/dep/srp/guidance/vaporintrusion/njje.htm.
The USEPA GW-SCREEN and GW-ADV model spreadsheets have been modified to
incorporate New Jersey specific parameters. A detailed discussion on the
use of the model for the calculation of a site-specific ground water screening
level is also included in Section 5.2 of the NJDEP Vapor Intrusion Guidance
(October 2005) document. Use of the model in the evaluation of a site
is subject to the review and approval of the Department.
Screening Level
Updates Based on Toxicity Factor Changes
Posted March 2006
The NJDEP has modified the screening level tables presented
in the Vapor Intrusion Guidance document (Oct 2005) based on new toxicity
factor information obtained in the latest (10/25/2005) USEPA Region III
Risk Based Concentration (RBC) Table. The updated screening levels and
the associated toxicity factor information have been noted in the applicable
tables with a double asterisk.
While the latest USEPA Region III RBC table lists updated
toxicity factors for four chemicals included in the NJDEP guidance (toluene,
1,1,1-trichloroethane, tetrachloroethene, and 1,1,2,2-tetrachloroethane),
the toxicity factor changes result in modifications to the actual screening
levels for only two of the chemicals (toluene and 1,1,1 trichloroethane).
The noncancer based toxicity factor changes for tetrachloroethene and
1,1,2,2 tetrachloroethane do not affect the actual screening levels for
these chemicals since the screening levels are based on the cancer endpoint.
As a result of the new information, the ground water,
soil gas and indoor air screening levels for toluene and 1,1,1 trichloroethane,
have been modified in the March 2006 NJDEP VIG tables. The screening levels
for toluene have increased, while the screening levels for 1,1,1 trichloroethane
have decreased compared to the previous values based on the new toxicity
information
As agreed to by the New Jersey Department of Health
and Senior Services, the indoor air Health Department Notification Level
(HDNL) for toluene (presented in Table 2) has been set at greater than
the new toluene residential Indoor Air Screening Level (IASL) of 5,100
ug/m3. The residential IASL, rather than the ATSDR acute Minimum Risk
Level (MRL), is the basis of the HDNL for toluene since the new toxicity
information used in the development of the updated IASL has not yet been
incorporated in the current acute MRL (of 3,800 ug/m3).
The USEPA Region III has removed three chemicals (cis-1,
2 dichloroethene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene) from
the RBC table that were included in the NJDEP VIG document. These chemicals
have also been removed from the March 2006 NJDEP VIG tables since the
USEPA National Center for Environmental Assessment (NCEA) no longer supports,
and has retired, the toxicological papers used as the basis of the previously
available toxicity factors.
Ground Water Screening Levels
and the Ground Water Quality Standards
Posted March 2006
The Ground Water Screening Levels (GWSLs) have been
updated based on the latest NJDEP Specific Ground Water Quality Standards
(GWQS) that were promulgated on November 7, 2005 and presented in Appendix
Table 1 of N.J.A.C. 7:9C. The generic GWSL for dibromochloromethane has
been lowered after consideration of the current GWQS for the chemical.
GWQS are not currently available for chloroethane, chloromethane, cyclohexane
and 4-methyl-2-pentanone (MIBK) as per Appendix Table 1 of N.J.A.C. 7:9C.
In the absence of GWQS, the GWSLs are set at the health-based ground water
screening values. As a result, the GWSLs for chloroethane have been lowered,
while the GWSLs for the other three contaminants remain the same.
Water Solubility and the Ground
Water Screening Levels
Posted March 2006
The vapor concentration of a chemical in equilibrium
with ground water reaches a maximum possible value when its ground water
concentration equals the water solubility. At this point, the vapor concentration
is equal to that observed for the pure chemical. If a calculated Ground
Water Screening Level (GWSL) is above the water solubility for a particular
chemical, this indicates that a vapor concentration in excess of what
is theoretically possible is required in order to result in an indoor
air concentration equal to the indoor air screening level. In this case,
the vapor intrusion pathway is not of concern at any groundwater concentration.
While this scenario did not affect any of the generic GWSL, which were
derived assuming sand soil, it did affect some screening levels for toluene
and ethylbenzene when alternate soil textures were used. A footnote has
been added to Table 3 (Ground Water Screening Levels for Alternate Soil
Textures) of the document indicating when the calculated GWSL exceeds
the water solubility. No GWSL is listed in the table in these cases.
Reduced Analytical Parameter
List
Posted March 2006
As a result of comments received during the external
review period for the Draft Vapor Intrusion Guidance, the Department agreed
that a reduced list of analytical parameters would be acceptable at contaminated
sites under certain circumstances. The Department determined that while
the initial indoor air and/or soil gas sampling rounds are to be analyzed
for the full suite of volatile chemicals, subsequent phases can employ
a reduced list of parameters as part of an approved vapor intrusion investigation
work plan.
The NJDEP Vapor Intrusion Guidance (October 2005) inadvertently indicated the potential for a reduced list
of parameters only for soil gas in Section 6.3.2.4 of the document. It
should be clarified that a reduced list of analytical parameters for indoor
air may also be acceptable after initial indoor air sampling rounds/phases
support the targeting of subsequent analytical parameters. This must be
agreed to by the Department and included in an approved vapor intrusion
work plan.
Editorial Correction to Section
6.2.3.2
Posted March 2006
The seventh (7th) paragraph in the above section of
the NJDEP Vapor Intrusion Guidance (October 2005)
should have been deleted from the document. This paragraph begins with
the following statement "Vertical profiling is recommended however
if a site-specific GWSL has been approved…”
Additions to the NJDEP Vapor
Intrusion Web Site
Posted March 2006
New Jersey versions of the USEPA Johnson and Ettinger
(J&E) model spreadsheets and instructions on the use of the spreadsheets
have been added to the web site at http://www.nj.gov/dep/srp/guidance/vaporintrusion/njje.htm.
The USEPA GW-SCREEN and GW-ADV model spreadsheets have been modified to
incorporate New Jersey specific parameters. A detailed discussion on the
site-specific use of the model for the calculation of a ground water screening
level is also included in Section 5.2 of the NJDEP Vapor
Intrusion Guidance (October 2005) document. Use of the model in the
evaluation of a site is subject to the review and approval of the Department.
A combined Chain of Custody Record/Field Test Data sheet
and instructions on its use has been added to the web site at http://www.nj.gov/dep/srp/guidance/vaporintrusion/vi_coc.htm.
Slides from the November 1, 2005 Vapor Intrusion Seminar
presented by the NJDEP at Rutgers University have been added to the web
site and may be accessed at http://www.nj.gov/dep/srp/guidance/vaporintrusion/rutgers2005/
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