Vapor Intrusion Guidance public review draft is now available.
MassDEP is seeking public comment on its revised Vapor Intrusion Guidance draft. This comprehensive draft document has been developed based on input MassDEP has received through discussions with the Indoor Air Workgroup and in other forums with LSPs, PRPs and other interested parties and written comments received on its July 2009 draft document.
MassDEP’s goal in developing this guidance document is to provide clear, practical and health protective guidance on vapor intrusion assessment and mitigation approaches that are consistent with 21E and the Massachusetts Contingency Plan. While parties conducting response actions may apply other approaches, provided they meet the requirements of the MCP, to address vapor intrusion sites, this draft reflects MassDEP’s recommendations and expectations for adequately addressing this complex pathway and achieving a protective result.
MassDEP welcomes your comments on the scope, content, and readability/clarity of this draft. Please consider and comment on the applicability of this guidance to vapor intrusion site work you have conducted or are conducting. Please submit comments by replying to the blog post at MassDEP’s Indoor Air Workgroup https://indoorairproject.wordpress.com/ by March 1, 2011. To facilitate MassDEP’s review and consideration of comments, please reference page and section numbers when commenting on specific topics or text.
The electronic version of the guidance consists of two files, the main body of text and the appendices. Please download both files for a complete copy.
Main Text:
- MassDEP_VI_Guidance_InterimDraft_2010-12 (REMOVED)
- MassDEP_VI_Guidance_InterimDraft_2010-12 (REMOVED)
Appendices:
- MassDEP_VI_Appendices_2010-12 (REMOVED)
- MassDEP_VI_Appendices_2010-12(REMOVED)
Appendices – REVISED 1/13/2011 – Revisions updated risk-based concentrations and commercial-industrial Threshold Values in Appendix I to reflect 8 hr/day exposure:
- Appendices-ALL-revised-2011-01-13 (REMOVED)
- Appendices-ALL-revised-2011-01-13 (REMOVED)
Filed under: News |
MassDEP Indoor Air Project 
The LSP Association is pleased to submit comments and suggestions on MassDEP’s December 2010 Vapor Intrusion Guidance Interim Draft.
Our cover letter provides a summary of the observations and issues that are of greatest concern to the Association. More detailed comments from LSPA members are provided in a separate document.
To view the Cover Letter, http://data.memberclicks.com/site/lspa/Vapor%20Intrusion%20Guidance%20Cover%20Letter.pdf
To view the Vapor Intrusion Comments, http://s3.memberclicks.com/site/lspa/Vapor%20Intrusion%20Comments.pdf
We appreciate the opportunity to comment on these
important issues, and look forward to receiving the Department’s responses.
Thank you,
LSP Association
[Cover letter and comments received by MassDEP from the Licensed Site Professional Association via email]
The LSP Association is pleased to submit comments and suggestions on MassDEP’s December 2010 Vapor Intrusion Guidance Interim Draft. Our cover letter provides a summary of the observations and issues that are of greatest concern to the Association. More detailed comments from LSPA members are provided in a separate document.
To view the Cover Letter, click here: https://indoorairproject.files.wordpress.com/2011/03/lspa_vapor-intrusion-guidance-cover-letter.pdf
To view the Vapor Intrusion Comments, click here: https://indoorairproject.files.wordpress.com/2011/03/lspa_vapor-intrusion-comments.pdf
We appreciate the opportunity to comment on these important issues, and look forward to receiving the Department’s responses.
Sincerely,
James S. Young, President
Wendy L. Rundle, Executive Director
LSP Association
[Comments received by MassDEP via email]
Attached please find comments to the MassDEP Draft Vapor Intrusion Guidance Document on behalf of Haley & Aldrich.
Thanks,
Rosemary McCafferty
Senior Risk Assessor
Haley & Aldrich, Inc.
Attached Comments:
Click to access 2011_0301_haley_aldrich_vi_guidance_comments.pdf
[Comments received by MassDEP via email from O’Reilly, Talbot & Okun Associates, Inc ]
Attached Comments:
Click to access jim_o_vi_comments.pdf
[Comments received by MassDEP via email with attachment]
Attached please find Columbia Analytical Services’ comments to the December 2010 Draft Vapor Intrusion Guidance. Please let me know if you have any follow up questions. I look forward to seeing the next version of the VI Guidance!
Best regards,
Alyson Fortune
Air Quality Scientist
Columbia Analytical Services, Inc.
Attached Comments:
https://indoorairproject.files.wordpress.com/2011/03/columbia_analytical_comments_for_madep_vi_guidance_022811.doc
[The following comments were received by MassDEP from GZA GeoEnvironmental Inc. via email]
Attached Comments:
Click to access gza_comments_on_vi_guidance_3-1-11.pdf
[Comments received by MassDEP via email]
NAIOP very much appreciates the opportunity to provide our comments, observations, and suggestions concerning the December 14, 2010 revised draft of the Department’s Vapor Intrusion Guidance. This letter provides both our general comments concerning the draft Guidance and more detailed comments concerning specific provisions in the draft Guidance.
We would appreciate receiving a detailed response to our comments, particularly in light of the importance of the issues addressed by the Guidance.
David Begelfer
Chief Executive Officer | NAIOP Massachusetts
Attached Comments:
Click to access march_2011_naiop_vapor_intrusion_comments.pdf
[Comments received by MassDEP via email]
Please find attached comments prepared jointly by Brian Magee of Arcadis and myself regarding the draft Vapor Intrusion Guidance Document.
Ileen Gladstone, P.E, LSP, LEED AP
Vice President
GEI Consultants, Inc.
Attached Comments (5 MB):
Click to access march_2011_vapor_intrusion_guidance_cover_letter__comments.pdf
[Comments received by MassDEP via email, including attachment]
Please find attached, comments on the draft MassDEP VI Guidance from Julianna and me, with input from key senior members of our internal VI Practice including Bill, Robbie and Todd M.. We hope that you will find our thoughts to be constructive, and we look forward to continued dialogue.
Kind Regards,
Todd N. Creamer, P.G. (CA, WY)
Senior Geologist
Attached Comments:
Click to access massdep_draft_vi_guidance_-_geosyntec_comments.pdf
March 1, 2011
Mr. Gerard Martin
Waste Site Cleanup, Compliance & Enforcement
MassDEP Southeast Region Main Office
20 Riverside Drive
Lakeville, MA 02347
Via email (gerard.martin@state.ma.us)
Re: Comments on 2010 Draft Vapor Intrusion Guidance
Dear Mr. Martin:
ECS is pleased to provide the following comments and questions regarding the Draft Vapor Intrusion Guidance published by the Massachusetts Department of Environmental Protection (MassDEP) in December 2010. These comments are attached for your review.
Should you have any questions, please do not hesitate to contact the undersigned.
Sincerely,
ENVIRONMENTAL COMPLIANCE SERVICES, INC.
Lori A. McCarthy
Project Manager
S. Page Fallon, Ph.D.
Technical Director of Risk Characterization
Section 1.3, Figure 1-1 (Page 6)
The use of “odors potentially attributable to groundwater and/or soil contaminants” in the first block of the flow diagram in Figure 1-1 appears too subjective, given the ubiquitous presence of many common contaminants in the environment. ECS suggests that combining the first two blocks of this flow diagram may yield a more realistic, yet still sufficiently conservative, result, while avoiding much costly assessment of conditions which may not exist: i.e. “…or odors potentially attributable to groundwater and/or soil contaminants and the building of concern has an earthen floor, fieldstone or concrete block foundation…, etc.”
The flow chart for the evaluation of vapor intrusion seems to suggest that even at sites where Method 1 GW-2 Standards would not apply (i.e. sites where average depth to groundwater is greater than 15 feet below grade) that the possibility of vapor intrusion should be evaluated through multiple lines of evidence if concentrations of volatile compounds in groundwater exceed ten times the GW-2 Standards within 100 feet of an occupied building.
As a hypothetical example, assume there is a site where a release of chlorinated solvents has occurred where groundwater is 25 feet below grade and groundwater at the site is not categorized as GW-1. The concentrations of all chlorinated VOCs in groundwater are less than GW-3 Standards. At one groundwater monitoring well located within 100 feet of the site building, vinyl chloride has been detected at a concentration of 25 ug/L and cis-1,2-dichloroethene has been detected at a concentration of 1,010 ug/L . Our understanding of the guidance is that since these concentrations are greater than ten times the GW-2 Standards (2 ug/L and 1,000 ug/L, respectively), the guidance is recommending the evaluation of a vapor intrusion pathway and use of multiple lines of evidence to rule out vapor intrusion. Is this correct? If this is the case, it would appear that the guidance is establishing a new and de facto Method 1 category of groundwater and Method 1 standards (10x GW-2) that would apply to all sites, not only sites where average depth to groundwater is less than 15 feet below grade. ECS questions why changes to the MCP have not been promulgated and proposed if, as this policy suggests, the Method 1 GW-2 Standards or assumptions upon which they are based are not protective of human health.
Also within this figure, it would seem to be impossible to answer “no” to the question “Is there the potential for contaminant movement along preferential pathways?” since variability in native and non-native subsurface materials could always potentially result in a preferential pathway.
Section 1.3.1 (Page 7)
“If soil contamination is present within 30 feet of an occupied structure, MassDEP recommends using additional lines of evidence including sampling of groundwater and soil gas to evaluate the potential for the vapor intrusion pathway”.
Is the “soil contamination” referred to in this sentence equivalent to the VOC contamination discussed in the previous paragraph (i.e., any detected compound in a USEPA Method 8260B), or is it “Contaminated Soil” as defined in the MCP (i.e., soil containing a Reportable Concentration of one or more oils and/or hazardous materials)?
At smaller properties located in densely developed urban areas (e.g. retail gasoline stations), the expansion of the area of concern from 10 feet to 30 feet could encompass the entire site property and several abutting properties, requiring multiple lines of evidence to rule out vapor intrusion even when Method 1 soil and groundwater standards are not exceeded.
It appears likely that application of these criteria, while possibly protective of vapor intrusion in certain settings, would result in situations which are practically irresolvable in urban and dense commercial developments. While in the case of soil and groundwater contamination we can hope to trace the extent of contiguous contamination from source to the limits of impact and therefore define the extent of the release; however that does not appear to be the case for contaminant vapors. As a consequence, in many urban and commercial settings, these criteria, and those similar criteria which apply to groundwater (Section 1.3.2) would result in numerous overlapping areas potentially associated with various sources, where the potential for vapor intrusion is presumed to exist and must be evaluated using multiple lines of evidence. Under these conditions, evaluation of the potential for vapor intrusion, and attribution of potential impacts to specific sources is not likely to yield unequivocal results.
Also with regard to this section, is the guidance here making a distinction between VOCs – as defined in the MCP and referenced in the preceding paragraph in the draft guidance – and “soil contamination?” Is “soil contamination” here equivalent to “Contaminated Soil” as defined in the MCP (soil containing concentrations of oils and/or hazardous materials at concentrations greater than or equal to reporting thresholds) – a much broader classification. Does the guidance distinguish between VOCs and MassDEP VPH/EPH carbon fractions? In prior communication regarding 310 CMR 40.0942(1)(d), MassDEP has indicated that Volatile Organic Compounds are those which would be quantified by analysis under USEPA Method 8260B, and would include the VPH Target analytes but not VPH carbon fractions. The draft guidance appears to suggest here that the presence of any compound, regardless of volatility and not expressly limited to VOCs, triggers an evaluation of multiple lines of evidence.
In reference to this section (specifically “Sub-slab soil gas surveys at these sites should address the entire building…”), the guidance is inconsistent with ASTM E1527 – 05, and will place LSPs at a significant disadvantage in the due diligence market. Departing significantly from the ASTM standards could have the unintended consequence of slowing future development and economic growth due to the additional uncertainty and risk associated with purchasing and developing properties in Massachusetts.
Section 1.3.2 (Pages 7 and 8)
The requirement or recommendation that the potential for vapor intrusion be evaluated using multiple lines of evidence where occupiable structures are present within 100 feet of locations where elevated concentrations of volatile contaminants are present in groundwater would appear to have very far-reaching implications, especially in urban areas, and yet does not appear to be based on any scientific foundation and appears incompletely defined. It appears that the 100 foot distance is based on some kind of informal consensus of various state regulators? Are there any depth criteria associated with this guidance (i.e., does groundwater present at 100 feet below grade and 100 feet from an occupied building present the same risk of vapor intrusion as groundwater at the same location which is 10 feet below grade? Are the occupants of a building that is 100 feet downgradient from a stable or shrinking contaminant plume at a risk equivalent to or greater than the occupants of a building located within 100 upgradient of a shrinking or stable plume?)?
The evaluation of the potential for vapor intrusion in areas where “high contaminant concentrations” are present within 100 feet of occupied structure(s) seems inconsistent with current regulations. Especially in urban or densely developed areas, the recommendation to provide secondary lines of evidence for properties located within 100 feet could impact multiple property owners. These offsite property owners may not be inclined to allow sampling of soil gas and/or indoor air due to concerns of legal liability for perceived risk (even if unlikely or nonexistent) by tenants or workers in their buildings. The guidance appears to indicate that even in situations where groundwater and soil samples have been collected at adjacent properties and were found to be below standards that additional lines of evidence (i.e. soil gas and/or indoor air sampling) would be required to achieve presumptive certainty for site closure. Buildings within a 100 foot radius of groundwater contamination that may meet applicable groundwater standards (and may be related to a site may be closed with an RAO) would now have the stigma of potential risk. The impact of this policy on property values and potential for blight in urban areas is not addressed anywhere within this policy. Additionally, ECS questions how this may impact the number of filings of Downgradient Property Status Opinions and whether owners of properties where OHM has not been detected in soil or groundwater but where OHM has been detected in indoor air or soil gas would qualify for DPS.
The statement “In cases where a monitoring well has not been or cannot be installed within 30 feet of a building, the groundwater concentrations of VOCs from the nearest monitoring wells should be used for comparison to the GW-2 Standards to evaluate the need for further evaluation of the vapor intrusion pathway” should be clarified with regard to the relative location of the source, receptors, and monitoring well(s). For example, at a given site there may be a well located 400 downgradient of a contaminant plume and within 40 feet of the downgradient side of building and a well located 100 feet downgradient of the contaminant plume and within 50 feet of the upgradient side of a building. Since the second well is located closer to the source, ECS opines that data from the second well would be preferred, and would provide more substantive information for the evaluation of risk even though it is located further from the footprint of the building of concern.
Section 1.3.3 (Page 9)
With regard to indoor air contamination and/or odors potentially related to volatile compounds in soil and groundwater, this section appears to suggest that even with multiple lines of evidence it may be impossible to close sites where OHM are presently used on the property (e.g. retail gasoline station and/or dry cleaner) or properties adjacent to these properties where transient odors may persist.
Regarding the statement “The structure of concern has an earthen floor…”, ECS suggests that the guidance should elaborate on what structures should be considered in the evaluation. As currently written, any structure (even a tool storage shed) could be considered a structure of concern if it has an earthen floor, fieldstone or concrete block foundation.
In reference to DNAPL present within 30 feet (horizontally) of an occupied building, this guidance seems to be contradictory to prior MCP guidance (WSC Policy 02-411) that suggests that vertical profiling of groundwater may be used to evaluate and/or eliminate the vapor intrusion pathway. For example, the wording of the 2002 guidance suggests that at a hypothetical site where DNAPL has been observed within 30 feet of the building and subsequent testing of the groundwater above the DNAPL had not detected compounds of concern above GW-2 that these data could be sufficient to evaluate and/or eliminate the vapor intrusion pathway in the risk characterization. The wording in this guidance seems to negate the prior policy recommendations.
Additionally, ECS asks that “volatile” light or dense non-aqueous phase liquid be defined. The definition of a “volatile” NAPL would seem to be readily apparent in some cases (e.g. gasoline, tetrachloroethene), but less obvious in other cases (i.e. LNAPL from a motor oil or fuel oil release).
Section 2.2.3.2 (Page 13)
ECS supports the development of threshold values that are specific to exposures in commercial and industrial buildings and are separate from those derived for residential properties.
Section 2.2.3.3 (Page 14)
The document did not provide guidance on the use of soil gas screening (i.e. PID measurements) with this interim draft. ECS questions whether this “Level 1” type screening evaluation (as described in the MassDEP WSC 02-411 policy) will be eliminated or viewed unfavorably as a line of evidence for evaluating and/or eliminating the vapor intrusion pathway.
Section 2.2.3.4 (Page 15), and the referenced Attachment III.1
It is ECS’ experience with indoor air sampling that confounding or contributing sources are a significant obstacle to achieving clear and definitive data to support a risk characterization and often times prohibit attaining the method detection limits (MDLs) that are cited in this document. Specifically in residential settings, requesting that the residents not use any cleaning or personal hygiene products, discontinue use of a cooking stove, and remove all potential sources seven days prior to sampling is extremely difficult and effectively requires that the residents relocate for the period of time prior to sampling. For a family already taxed by the financial and emotional costs of assessing and remediating their home, the additional expense and stress to these families can be significant.
The list provided in the attachment is not exhaustive, and ECS would recommend that the list include that burning of candles or gel chafing fuel (Sterno) should be avoided and that all dry cleaned clothing should be removed from the residence prior to sampling.
Even in instances where confounding or contributing indoor sources of OHM can be eliminated, laboratories may require that “low-level” canisters be used to achieve the low detection limits. The request for “low-level” canisters may almost double the cost of analysis. These costs may disproportionately affect home owners performing assessment activities since the threshold values for residences are lower. For retail gasoline distributors conducting assessment and remediation activities that are covered under the Underground Storage Tank Petroleum Product Cleanup Fund (i.e. “21J”), the current reimbursement fee schedule does not include a line item for reimbursement of the costs of analysis via the “low level” methods.
Tables 2-1 and 2-2 (Page 16)
ECS questions why the primary line of evidence on these tables is “<2x GW-2”. If the applicable standard for the site groundwater is GW-2, then why should twice the GW-2 standard be used as the benchmark? Throughout the guidance, the use of “alternate” GW-2 standards (10x GW-2, 2x GW-2) seems inconsistent with the MCP.
Section 2.3.2 (Page 18)
ECS opines that the text “Sampling locations at sites with current/former solvent use should include…” should be changed to “Sampling locations that should be considered for investigation should include…” since there may be other lines of evidence or information about the facility that would allow the LSP to eliminate of some of these sampling locations.
Section 2.3.3 (Page 19)
ECS contends that to achieve presumptive certainty under this guidance that it should not necessary to request that all target analytes of the TO-15 method be reported for soil gas and/or indoor air samples. (This is restated in Section 2.3.4) There is a high likelihood that confounding compounds that may be related to indoor air sources or commercial/industrial operations unrelated to the release that is being investigated. ECS opines that information collected regarding the nature and extent of the released OHM can be used to appropriately and thoughtfully pare the list of target analytes, and that this should meet the standard for presumptive certainty provided all potential compounds of concern identified in the risk evaluations are reported from the analyses of the soil gas and/or indoor air samples. This is stated in Section 2.4.1, but should be stated in this section also.
With regard to the minimum number of sampling events, ECS recommends that either one round or two rounds (and two rounds or four rounds, as noted in Section 2.3.4) be established as the minimum, since the document states “one to two” (and “two to four” in Section 2.3.4) and so does not define a minimum requirement. Additionally, the text “…one of which should be in winter” should be changed to “…one of which should be winter if it is deemed necessary”. The indoor air sampling guidance (WSC 02-430) indicates that in some cases highest soil gas concentrations have been reported in samples that were during spring rains and thaw, and in other cases in the fall immediately prior to operation of the building heating system. These conflicting recommendations should be resolved prior to the promulgation of the final policy.
Section 2.4.2 (Page 22)
Currently the MCP states that “…Groundwater shall be defined to be in category GW-2 if it is located within 30 feet of an existing or planned building or structure…” Wording in this section of the guidance seems to circumvent a regulatory change that would make groundwater within 30 feet of any possible future structure (not just “planned structure”) category GW-2.
Regarding sampling at locations that use compounds of concern in a licensed and permitted manner and inability to achieve a Permanent Solution, the guidance seem to prohibit the use multiple lines of evidence that demonstrate the release is not contributing to indoor air issues in conjunction with the implementation of an AUL would provide reasonably assuredness that a condition of No Significant Risk is maintained at the Site (“generally not possible”) and achieve a Permanent Solution. If this is not the case, the wording should be changed to reflect this line of reasoning.
Section 2.4.3 (Page 24)
The assumption that a basement within a dwelling is utilized as a living space may be applicable for future use and current use if there is evidence of such; however, if current use would suggest otherwise (which may be important in the evaluation of Substantial and Imminent Hazards), the risk assessor should be able to utilize reasonable estimates of the exposure period in the determination of EPCs. A recommended change should state that “Basements of any height that show evidence of current activity should be considered living or working space. Any basement with at least seven feet of head room in an occupied residential dwelling should be considered living space for the calculation of EPCs and determination of risk under future conditions.”
Section 2.4.3.1 (Page 23)
ECS opines that data can be both variable (or perhaps “seasonal” is a more accurate description) and consistent. If the data indicate that across several seasons that the highest concentrations (of similar magnitude) are observed during the winter and the lowest concentrations (of similar magnitude) are observed during the spring, the concentrations are variable, but the trends are seasonably consistent. In this situation, averaging of representative data should be accepted for the calculation of EPCs.
Section 2.5.1 (Page 26)
The recommendation to place an AUL on an area based upon a groundwater concentration seems inconsistent with current AUL guidance. ECS’ understanding is that the AUL instrument should not be used to prevent the installation of a potable well, partially due to the mobile nature of dissolved phase OHM. It would seem that the use of an AUL based upon concentrations of compounds in groundwater that may result in vapor issues to a current and/or future building(s) should also be discouraged.
This section of the guidance would also suggest that even if a risk characterization concludes that a condition of No Significant Risk is applicable to the Site for current and future uses, that an AUL would be required for closure if concentrations of OHM in groundwater exceed Method 1 GW-2 Standards.
With respect to operation of a subslab depressurization system, PRPs may be better served if MassDEP updated their policy regarding “Construction of Buildings in Contaminated Areas” (WSC-00-425) to reflect this recommendation. Revisions to this policy would be a more relevant mechanism to convey this information and is the most likely document that would be referenced should a property owner approach a consultant for assistance with constructing a building at a former or current MCP site.
Table 3-1 (Page 42)
ECS has observed at some locations, the heterogeneous nature of fill materials beneath the slab can result in variability in the sub slab differential under active venting. In these situations, a pressure differential may be measured but may not be effective at eliminating vapor intrusion.
Additionally, ECS questions why passive systems are not recommended to mitigate Imminent Hazards or Significant Risk if they can be demonstrated to be effective at eliminating the vapor intrusion pathway. Section 3.5.3 further states that “these systems are less predictable and efficient at preventing vapor intrusion than active systems.” ECS would like clarification if this is a matter of opinion, based upon data from published studies, or based upon experience at Disposal Sites with these kinds of systems.
Appendix VIII, Table VIII-1
ECS appreciates the examples provided in this table to assist in the writing of AULs for future building construction. ECS is aware, however, that the filing and subsequent implementation of AULs can be difficult and fraught with pitfalls. The filing of the AUL instrument does provide a caveat emptor for potential future buyers and developers of a property where a release of OHM has occurred (whether this be positive or negative remains to be seen), but does little to provide certainty that the new property owner will remain out of the MCP system even if they follow the construction recommendations as outlined in the AUL and the advice of an LSP/Engineer who designs and installs a vapor barrier and/or subslab depressurization system.
ECS is aware that MassDEP is currently updating its guidance document for the filing of AULs (WSC 99-300). Information regarding the filing of AULs at sites where a potential vapor intrusion pathway exists should also be included in the updated AUL guidance.
Thank you for the opportunity to comment on the MassDEP Vapor Intrusion Guidance – Interim Draft dated December 2010.
Below are several comments:
Section 3.4.2.3 Membrane Systems, pg. 39.
CETCO Comments:
Liquid Boot spray-applied membrane in conjunction with passive venting has been successfully used for vapor intrusion mitigation in new construction for over 20 years. Liquid Boot standard product is 60-mil thickness. CETCO has diffusion coefficient data for Liquid Boot versus chlorinated solvents. These diffusion coefficients can be inserted into the USEPA modified Johnson and Ettinger model to estimate risk mitigation. Thus, we request the following:
• Change membrane thickness from “at least 70-mil” to “at least 60-mil”.
• Membranes allow vapor diffusion, but at a reduced rate. Replace words “prevent” and “preventing” with “reduce” and “reducing”, respectively.
• Third paragraph, first sentence. Add word “significantly” before “absorb” to be consistant with other references in this section to absorbing VOCs.
Section 3.4.2.4 Passive Venting, pg. 41.
CETCO Comment:
As discussed above, membrane diffusion coefficients can be used to estimate risk mitigation. Thus, we request that passive venting (along with a membrane barrier) not be limited to only cases when concentrations of contaminants in indoor air are at or near the Threshold Values.
Sincerely,
Jim Olsta
Technical Manager
CETCO Remediation Technologies
NAIOP Massachusetts, the Commercial Real Estate Development Association, appreciates the opportunity to submit comments on the draft Vapor Intrusion Guidance. NAIOP’s full comment letter can be viewed here:
Click to access MARCH_2011_NAIOP_VAPOR_INTRUSION_COMMENTS.pdf
Thank you for the opportunity to comment on the Vapor Intrusion Guidance Draft. Below are several comments presented on behalf of Air Toxics Ltd. specifically related to sample collection and analytical procedures.
Appendix III
III.2.3.3 Passive Badge Samplers
Sampling rates have been measured for many VOCs for various commercially available passive samplers. Proper selection of sampler geometry and sorbent can yield quantitative VOC measurements in indoor and outdoor air with minimal effects of humidity and back diffusion. The measurement uncertainty introduced by the sampling rate is typically far less than the measurement uncertainty introduced by temporal variability. Passive sample collection may be an ideal solution once the compounds of concern have been identified, including the post-mitigation maintenance phase.
Attachment III.3 Procedure for the Collection of Sub-Slab Soil Gas Grab Samples
2.2.2 Canister Sample Collection
As described in EPA Method TO-15, a 2 micron particulate filter prior the flow controller and canister valve is recommended. If using a 6L canister for a grab sample, the flow rate will be much higher than the typical 0.1 to 0.2 LPM flow range. A flow restrictor may be appropriate for this application.
Sorbent tubes can also be used for grab samples for sub-slab soil vapor. Vapor is pulled through the sorbent tube using a volumetric syringe connected to the outlet side of the tube.
Attachment III.4 Procedure for the Collection of Time-Weighted Air Samples
3.0 Sample Collection
The conventional flow controller design for flow rates less than 10 ccm is the 2-part flow controller comprised of a fixed orifice and a back pressure regulator. There is a hex set screw on the back pressure regulator to make fine adjustments to the flow rate. For a 24-hour 6L canister sample, the flow rate is set at approximately 3.5 ccm. Utilizing a flow controller with only a fixed orifice will not result in constant flow over the sample collection duration. As the canister fills, the flow rate will decrease.
Heidi Hayes, Technical Director
Air Toxics Ltd.
Shell Global Solutions is pleased to submit to you the attached comments on the draft vapor intrusion guidance. Unfortunately, the comments could not be uploaded to the website because of the embedded attachments. If you have any questions, please do not hesitate to contact me. Thank you for provided us the opportunity to comment.
Kind Regards,
Matthew Lahvis
Shell Projects and Technology (US)
[Comment received by MassDEP from Shell Global Solutions via email, with 6 attachments]
PDF of Comment Letter: https://indoorairproject.files.wordpress.com/2011/03/sgs-comments-madep-2011-final.pdf
Attachment 1 – Riis 2010: https://indoorairproject.files.wordpress.com/2011/03/sgs-attachment-1.pdf
Attachment 2 – Buzkurt et al: https://indoorairproject.files.wordpress.com/2011/03/sgs-attachment-2.pdf
Attachment 3 – DeVaull 2011: https://indoorairproject.files.wordpress.com/2011/03/sgs-attachment-3.pdf
Attachment 4 – Hers, et al 2011: https://indoorairproject.files.wordpress.com/2011/03/sgs-attachment-4.pdf
Attachment 5 – ch 05 Lahvis 2010 (proof): https://indoorairproject.files.wordpress.com/2011/03/sgs-attachment-5.pdf
Attachment 6 – McHugh & McAlary 2009: https://indoorairproject.files.wordpress.com/2011/03/sgs-attachment-6.pdf
COMMENTS ON THE MassDEP VAPOR INTRUSION GUIDANCE DOCUMENT
Page Number: ____7___________________________________
Section Number:
__1.3.1__________________________________
Comment: ___In the 3rd paragraph that last sentence reads “….MassDEP recommends using additional lines of evidence including sampling of groundwater and soil gas to evaluate the potential for a vapor intrusion pathway.” Are they referring to any type of soil gas or specifically sub-slab soil gas? Would active soil gas sampling outside the building footprint be sufficient if the sample was collected within the defined parameters set forth in 310 CMR 40.0942(1)(d) (six feet horizontal and 10 feet vertical from a building)?
Page Number: ____12__________________________________
Section Number: __2.2.1__________________________________
Comment: as related to my comment/question above. Is active soil gas (soil gas outside the building footprint) considered as an accepted “lines of evidence”
Page Number: ____16__________________________________
Section Number: __2.2.4__________________________________
Comment: ___Can the lines of evidence matrices in Tables 2-1 and 2-2 be more detailed so that they spell out all the different scenarios. For example can the scenario of groundwater contamination 50xTV be added to the matrix? Any deviation of the listed matrix I guess would be assumed to require indoor air sampling but I believe it might be clearer if all scenarios were spelled out. Would a decision flow chart work better in this case?
Comments received by email on 2/28/2011 from:
Cynthia Fuller, Health Risk Assessor/Project Manager
WILCOX & BARTON, INC. ENVIRONMENTAL AND ENGINEERING SERVICES
Click to access c_fuller_massdep-vapor-intrusion-guidancecomments-030111.pdf
SEE ALSO: Comments posted on the VI powerpoint presentation thread:
Comments received by MassDEP through email:
Old Boston Restorations, Inc.
111 West Concord Street (Rear)
South End, Boston, MA 02118
February 15, 2011
By Email (gerard.martin@state.ma.us) and U.S. Mail
Mr. Gerard Martin
Waste Site Cleanup, Compliance & Enforcement
MassDEP Southeast Region Main Office
20 Riverside Drive
Lakeville, MA 02347
Re: Comments Concerning Draft Vapor Intrusion Guidance
Dear Mr. Martin:
This letter will not be as technical as many you may receive, but I thought it might be helpful for you and DEP to hear the views of one small developer. For some 30 years now, through Old Boston Restorations, Inc., I have been redeveloping in the South End. In that time, the South End has gone from a blighted neighborhood to a vibrant, mixed-income, mixed-race area. The BRA and the city of Boston participated in the urban renewal of the South End. However, neighborhoods are not revitalized by urban planning. They are revitalized by individual investments, one building, and one block at a time.
I have now read through the draft Guidance three times. I have three basic comments.
First, the Guidance reads to me like DEP wants to return Boston to pre-colonial conditions. E.g., the increased emphasis on restoring conditions to more than safe levels, to pre-historic “Background” conditions. That is not fair, let alone realistic. It puts the City of Boston and Boston property owners at a severe disadvantage with greenfields Towns and greenfields owners. To put a heightened emphasis on achieving “Background” when in many cases owners are dealing with only very small, already-safe levels of compounds in air makes no sense. DEP cannot repeal the law of diminishing returns.
Second, please understand the enormous damage DEP does to property owners and the City when it moves the goal line. The BRA and the City also like to see progress too, and they set new standards from time to time. But they don’t tell existing property owners that all their work so far has been useless or not good enough. The BRA and the City give owners time to plan and allow improvements to occur when owners are spending money on construction and so have funding lined up. It is wrong and completely destructive of the certainty builders, lenders and property owners need when DEP continually ratchets up the requirements, and especially when DEP invalidates past 21E work which met the standards at the time work was done. DEP cannot with a straight face say that it values and supports brownfields redevelopment when it invalidates Response Action Outcomes in place for more than five years because DEP wants to retroactively apply new standards. Yet that is exactly what DEP has done with this Vapor Intrusion campaign and we both know it. DEP has a credibility problem in the private market because of this. DEP should re-commit itself going forward not to audit or invalidate RAOs after five years, absent fraud or clear failure to meet the standards at the time the RAO was filed.
Last but not least, as I read the draft, Guidance DEP wants property owners to install fans in subslab venting systems, but then DEP blames the Regulations for the prohibition on permanent solution, Class A Response Action Outcomes for sites using venting fans. Well, if DEP can write a draft Guidance to change the rules, surely DEP can amend the Regulations to allow Class A RAOs for sites that provide an extra margin of safety by using venting fans. I am happy to install venting fans, but not if it means I have to pay from now to eternity to do monitoring and to file semi-annual reports with DEP and never get to permanent solution site closure. Additionally, nobody is going to buy property from me or lend to me or my buyers under those obligations. The cost of the paperwork will quickly swamp the cost of the electricity for the fans, the fans themselves and even the venting systems. Please issue new Regulations that clearly and cleanly allow Class A RAOs to be filed where vent fans are used, before you issue or enforce the final Guidelines.
Thank you for reading my comments.
Sincerely,
David Parker, President,
Old Boston Restorations, Inc.
Cc: Kenneth L. Kimmell, Commissioner, DEP
(One Winter Street, Boston, MA 02108)
James W. Hunt, III, Chief of Environmental and Energy Services, City of Boston
(1 City Hall Square, Room 603, Boston, MA 02201)
(Both By U.S. Mail)
Comments received by MassDEP via email:
Thank you for taking the time to speak with me today. As discussed, Grace has some comments we wanted to share on the MassDEP Vapor Intrusion Document. Attached is a letter with those comments. We look forward to the next step in the development process of the MassDEP document and hope that we can work with the MassDEP on this document.
Please contact me if you have any questions.
Craig Boucher
WR Grace
Waterproofing Product Manager
Attached PDF file:
Click to access massdep-vapor-intrusion-guidance-grace-comments.pdf
The following comments are submitted by AECOM organized by sections in the guidance document.
Section 1 – Introduction
Page 7, Section 1.3.1
It is stated that “concentrations of VOCs in soil at which the potential for vapor intrusion is likely to occur have not been established, as even low levels, below S-1 Soil Standards, have the potential to be a significant source. The potential for vapor intrusion must be evaluated if VOCs are detected in the soil within the distances outlined above…….. If soil contamination is present within 30 feet of an occupied structure, MassDEP recommends using additional lines of evidence including sampling of groundwater and soil gas to evaluate the potential for a vapor intrusion pathway.” However, as with previous guidance documents, MassDEP has not provided levels in soil that are “categorically” considered to be/not be a significant source of vapors to indoor air. Along the same lines, the Guidance discusses AULs for future buildings when the Method 1 GW-2 standards are exceeded but does not discuss AULs for future buildings if/when VOCs in soil are of concern. Does this mean that the MassDEP is not overly concerned with soil impacts to the indoor air of future buildings? The MassDEP has missed an opportunity to provide guidance on how to properly evaluate VOCs in soil and insure that indoor air is not impacted currently or in the future.
The above comment also applies to Appendix VIII, Sections VIII5.3.1 and VIII5.3.2.
Pages 7-8, Section 1.3.2
With respect to the Method 1 GW-2 standards, the Guidance states that “they apply when groundwater is the only source of contamination to indoor air.” This is inconsistent with the MCP since the MCP does not make this statement. The Guidance makes reference to (310 CMR 40.0942(1)(b)); however, this is an overly broad and improper interpretation of the MCP since this section of the MCP refers to impacts to other environmental media in addition to soil or groundwater such that a Method 1 evaluation alone cannot be used.
Section 2 – Assessment
Page 12, Section 2.2.2
Section 2.2.2 discusses that there may be cases where direct indoor air measurements are not practical or possible. This section states that in these situations, “MassDEP recommends the use of soil gas screening values discussed in Section 2.2.3.2, and if necessary, the estimation of indoor air concentrations using the approach discussed in Section 2.3.4.” However, Section 2.2.3.2 does not discuss the evaluation of soil gas or use of the soil gas screening values. In addition, Section 2.3.4 discusses the approach for conducting indoor air measurements, but does not discuss estimating indoor air concentrations when direct measurement is not practical or possible.
Page 16, Section 2.2.4
Tables 2-1 and 2-2 present the lines of evidence evaluation criteria for determining whether indoor air is a current pathway. The lines of evidence evaluation references 2x GW-2 as a criteria for this evaluation. No justification was provided for the 2x factor. The Method 1 GW-2 standards were developed using an attenuation factor based on the Johnson & Ettinger model, which incorporates many conservative assumptions. Many Method 2 evaluations performed by AECOM have shown that although VOCs in groundwater were at levels significantly above the Method 1 GW-2 standards, soil gas and/or indoor air sampling has demonstrated that impacts to indoor air are unlikely or are not occurring. As such, a 2x factor seems overly conservative and one could just as easily, and may be more appropriately, use a 5 x or 10x factor.
Pages 16 and 19, Sections 2.2.4 and 2.3.3, and Pages 26 – 27, Section 2.5.1
Tables 2-1 and 2-2 present the lines of evidence evaluation criteria for determining whether indoor air is a current pathway. The regulated community requires guidance as to how, assuming worst case conditions, it can be determined whether indoor air is a future pathway. For instance, if there is very limited or no VOC contamination in soil and the depth to groundwater is well below a typical building foundation depth, it seems that collecting soil gas immediately above the water table represents worst-case soil gas concentrations. If the soil gas results are well below the Sub-Slab Soil Gas Contaminant Levels defined in Table 2-1 it can be concluded that indoor is also not a future pathway.
Since the Soil Gas Contaminant Levels in Table 2-1 are defined as being applicable for “Sub-Slab” samples only, it seems that the MassDEP is concerned that soil gas will accumulate under buildings. In fact, Page 19, Section 2.3.3 states that “soil gas directly beneath a slab or basement is most likely to be representative of what may be entering the building. If samples cannot be obtained directly beneath the slab due to access issues, soil gas samples obtained adjacent to the building and under pavement can be used to characterize subsurface conditions.” However, because vapor migration is primarily a diffusive process within soil, vapors will move across a concentration gradient going from high to low concentrations. As such, vapors cannot occur under a building at concentrations greater than deeper soil vapor concentrations (i.e., they cannot build up under a building). This was discussed in a presentation by Lilean Abreau, ARCADIS, at the USEPA Vapor Intrusion Workshop, AEHS Conference, March 2010 in San Diego, CA. Based on the above considerations, deep soil gas is considered to provide a worst-case indication of the concentrations of VOCs in soil gas under current or future conditions. This conclusion provides an opportunity for a lines of evidence evaluation of the current as well as future indoor air pathway.
Page 25, Section 2.4.4, Table 2-4
Table 2-4 provides the recommended indoor air exposure assumptions for residential and worker scenarios. It is understood that the assumptions provided for a residential exposure scenario are intended to represent the most extreme scenario in which a resident is homebound and never leaves their residence. However, this scenario is likely not going to apply to the majority of residences being evaluated under this guidance document. Therefore, it seems more appropriate to have the default exposure frequency be consistent with USEPA’s default exposure frequency of 350 days per year (which assumes some time away from the home) with a recommendation for altering this frequency in the case that this is not likely to be adequately protective on a site-specific basis.
Section 3 – Mitigation
Page 29, Section 3
The draft guidance document provides a good overview of the various ways for mitigating the VI pathway.
Page 47, Section 3.6
Relative to samples being collected during the heating season (as referenced here and elsewhere in document), although AECOM understands the dynamics of air flow in a structure when the heating system is on, we suggest that MassDEP be aware of recent research that has questioned the importance of heating season sampling. (Research by the New York State Department of Environmental Conservation presented at various conferences over the years, including the UMass Soils Conference in 2009, which presented a temporal study from 16 houses that were sampled over 18 months.) There may be a situation where a site has favorable results for closure at a time in the spring or summer, but does not have two rounds from the heating season (because of access issues or other), and therefore, site closure would have to be delayed until the upcoming heating season and associated sampling.
Section 4 – Regulatory Framework
Page 48, Section 4
In general, the regulatory framework write-up in this section is well done and provides a good overview of MCP requirements and processes.
Page 59, Section 4.5.1.1
The requirement for post-remediation indoor air monitoring of at least three samples collected over a two year period seems excessive. We understand the need to access seasonal variations and to confirm that levels are consistent from one year to another, but we would hope that the use of additional lines of evidence could be used in the absence of completing monitoring over two years (e.g., additional samples over one year, historical groundwater elevations and concentrations, etc.).
Page 63, Section 4.5.2.2
Example Vapor Intrusion Scenario – These are very worthwhile, and there should be consideration to include more of them throughout Section 4 in the final version.
Page 66, Section 4.5.3.1
Regarding the 3rd criteria for providing presumptive certainty in support for a Permanent Solution (groundwater concentrations of COCs are to be less than GW-2 standards based on seasonally representative data), can the groundwater concentrations at each location (e.g., well) be averaged over time and then compared to standards, assuming there is a stable or downward trend?
Page 71, Section 4.7.4
Regarding the references to “groundwater concentrations” for the three categories and the comparison of them to GW-2 standards; are the groundwater concentrations to be used for this evaluation suppose to be averaged over time (e.g., EPCs), historically the highest results, the latest round, or other? Does the depth to groundwater figure into this approach, or is it implied because of the reference to GW-2 standards (i.e., less than 15 feet deep)?
Page 72, Section 4.7.4, Category C
Is it practical to expect a new building construction to remain unoccupied for a period of two years to test the indoor air? We understand the need to access seasonal variations and to confirm that levels are consistent from one year to another, but we would hope that the use of additional lines of evidence could be used in the absence of completing monitoring over two years.
Page 71-73, Section 4.7.4
Same comment as noted above under Page 7, Section 1.3.1.
Regards,
David G. Austin, LSP, LEP, PG (Senior Project Manager) and Timothy F. Markey (Senior Risk Assessor)
Minor corrections have been made to a few comments submitted by David G. Austin and the following comments replace the previous comments that correspond with these:
Section 1 – Introduction
Page 7, Section 1.3.1
It is stated that “concentrations of VOCs in soil at which the potential for vapor intrusion is likely to occur have not been established, as even low levels, below S-1 Soil Standards, have the potential to be a significant source. The potential for vapor intrusion must be evaluated if VOCs are detected in the soil within the distances outlined above…….. If soil contamination is present within 30 feet of an occupied structure, MassDEP recommends using additional lines of evidence including sampling of groundwater and soil gas to evaluate the potential for a vapor intrusion pathway.” However, as with previous guidance documents, MassDEP has not provided levels in soil that are “categorically” considered to be/not be a significant source of vapors to indoor air. Along the same lines, the Guidance discusses AULs for future buildings when the Method 1 GW-2 standards are exceeded but does not discuss AULs for future buildings if/when VOCs in soil are of concern. Does this mean that the MassDEP is not overly concerned with soil impacts to the indoor air of future buildings? The MassDEP has missed an opportunity to provide guidance on how to properly evaluate VOCs in soil and ensure that indoor air is not impacted currently or in the future.
The above comment also applies to Appendix VIII, Sections VIII5.3.1 and VIII5.3.2.
Page 59, Section 4.5.1.1
The requirement for post-remediation indoor air monitoring of at least three samples collected over a two year period seems excessive. We understand the need to assess seasonal variations and to confirm that levels are consistent from one year to another, but we would hope that the use of additional lines of evidence could be used in the absence of completing monitoring over two years (e.g., additional samples over one year, historical groundwater elevations and concentrations, etc.).
Page 71, Section 4.7.4
Regarding the references to “groundwater concentrations” for the three categories and the comparison of them to GW-2 standards, are the groundwater concentrations to be used for this evaluation supposed to be averaged over time (e.g., EPCs), historically the highest results, the latest round, or other? Does the depth to groundwater figure into this approach, or is it implied because of the reference to GW-2 standards (i.e., less than 15 feet deep)?
Page 72, Section 4.7.4, Category C
Is it practical to expect a new building to remain unoccupied for a period of two years to test the indoor air? We understand the need to assess seasonal variations and to confirm that levels are consistent from one year to another, but we would hope that the use of additional lines of evidence could be used in the absence of completing monitoring over two years.
I fully agree with Brian’s comments in regard to pg. 35 Sec. 3.3.1.4 the thickness of the membrane and pg.33 Sec. 3.3.1.1 O&M of the system.
Bill Hoyerman
Please consider the following comments and suggestions on the Draft Vapor Intrusion Guidance:
pg.33 Sec. 3.3.1.1 Active Sub-Slab Depressurization (SSD) System – Note that while these systems are effective if properly designed and installed, they are easily forgotten if not routinely monitored and maintained due to blower failure. A maintenance contract requirement is recommended as part of an IRA/RAM plan for these systems.
pg33; 2nd para. Suggest changing “negative pressure” to “vacuum”.
pg.34 Sec. 3.3.1.1 – Suggest a more specific definition of “competent professional” for design of these systems. Is a P.E. stamp required for design drawings (as is the case for HVAC design work)?
pg. 35 Sec. 3.3.1.4 – Why is a minimum 60 mil membrane required for sealing floors. walls? A more important consideration may be the compatibility of the membrane material swelling/breakthrough characteristics of the membrane and contaminant of concern. Also, certain membranes (such as PVC) attract rodents which are attracted by the plasticizer in the membrane.
pg.35 Sec. 3.3.2 – Suggest changing “carbon sorption” to “activated carbon adsorption”.
pg. 38 Sec. 3.4.2.3 – This section specifies a minimum 70 mil membrane for passive venting systems. Note that thinner materials can be equally effective depending on the contaminant of concern and membrane material. Also note that thick membrane materials can by very difficult to install. This is particularly true of HDPE under cold weather conditions.
pg. 40 Sec. 3.4.2.4 Passive Venting – The effectiveness of passive venting systems may be underestimated. Note that passive venting system have been used in building design for decades to control methane migration where buildings are in close proximity to landfills. The same same design concepts and construction methods can be successfully applied to vapor intrusion problems concerning VOCs. A properly designed interceptor trench system with venting pipes can work well and is virtually maintenance free.
Finally, I suggest that the guidance manual also include a section on crawlspace ventilation systems as a feasible option for vapor intrusion control, where depressurization is not practical.
Thank you for the opportunity to comment on the manual.
Brian V. Moran, P.E., LSP
Norfolk-Ram Group, LLC
Interested in commenting on the new VI draft? Thank-you!
Here’s how you can make the comment and subsequent revision process go smoother…
MassDEP hopes for and expects both general (“big-picture”) and specific (technical corrections, grammatical edits) comments.
You’ll notice that the guidance is divided into multiple sections, subsections, sub-subsections and so on. To the extent feasible, please reference (section number and page) the item you are commenting on.
Looking toward future revisions, the most useful comments to MassDEP include three components: (1) a citation of the existing language, (2) discussion of the issue/concern, including practical implications and/or technical, policy or regulatory references, and (3) proposed replacement language.
While the Word documents posted above (https://indoorairproject.wordpress.com/2010/12/14/vapor-intrusion-guidance-public-review-draft/) are “locked” to preserve formatting, text can easily be cut-and-pasted from them to aide in your review/comment.
[In fact, a full, editable copy can easily be created in 4 keystrokes: Ctrl-A, Ctrl-C, Ctrl-N and Ctrl-V ]
Finally, MassDEP encourages you to post your comments on this blog so that others may benefit from your insights and the discussion which may result. Post your comments early and often – you do not need to wait until February 28th to begin, and you do not need to wait until you have ALL you comments of ALL sections! [MassDEP will post comments received by email or in hard copy.]
If you have any questions concerning the draft document or the review/comment process, please feel free to post a note on the blog.
– MassDEP Bureau of Waste Site Cleanup