VAPOR ENCROACHMENT VAPOR INTRUSION; TRANSACTIONAL ASSESSMENT OF THE POSSIBLE VAPOR INTRUSION PATHWAY

Transcription

1 VAPOR ENCROACHMENT VAPOR INTRUSION; TRANSACTIONAL ASSESSMENT OF THE POSSIBLE VAPOR INTRUSION PATHWAY By Russell Griebel, P.G., C.P.G. United Consulting

2 Presentation Talking Points How We Got Here Vapor Encroachment vs. Vapor Intrusion Due Diligence VE Assessment What Next

3 Evolution of Vapor Considerations EPA- Assessing Potential Indoor Air Impacts for Superfund Sites, 1992 EPA Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soil (Subsurface Vapor Intrusion Guidance), 2002 ITRC Vapor Intrusion at Brownfield Sites, 2003 EPA User s Guide for Evaluating Subsurface Vapor Intrusion into Buildings, 2004 EPA All Appropriate Inquiry, 2006 ITRC Vapor Intrusion Pathway: A Practical Guideline, 2007 ITRC Vapor Intrusion Pathway Inv. Approaches For Typical Screening, 2007 EPA Engineering Issue: Indoor Air Vapor Intrusion Mitigation Approaches, 2008 ASTM E Standard Guide for VE Screening (Updated -15) ASTM E Standard Practice for the Phase I ESA Process EPA AAI final rule, Amendment to Standards and Practices for AAI Under CERCLA, 2013 ITRC Petroleum Vapor Intrusion, 2014

4 June 2015 EPA Released Final Guides OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air or Vapor Intrusion Guide Technical Guide for Addressing Petroleum Vapor Intrusion at Leaking Underground Storage Tank Sites or PVI Guide

5 Vapor Intrusion Guide The guidance does not: Offer recommendations for VI assessments associated with real estate transactions Modify existing guidance regarding landowner liability protection (i.e. AAI)

6 All Appropriate Inquiries 40 CFR Part 312 Process of evaluating a property's environmental conditions and assessing the likelihood of contamination (i.e., soil, liquid/groundwater or vapor).

7 Why AAI Under CERCLA, persons may be held strictly liable for cleaning up hazardous substances at properties that they either currently own or operate or owned or operated in the past. The Small Business Liability Relief and Brownfields Revitalization Act (the Brownfields Amendments ) amended CERCLA to provide protections from liability for certain landowners and prospective purchasers. CERCLA provides three types of liability protections for landowners and prospective purchasers of real property: Innocent landowners - did not know and had no reason to know of a release Contiguous property - contiguous to contamination source Bona fide prospective purchasers - may buy property with knowledge of contamination, provided they bought the property after January 11, 2002

8 ASTM Latest standard consistent with AAI EPA formally recognized ASTM E as AAIcompliant, December 2013 EPA used the term vapor migration or vapor releases more than 10 times n..important revisions to the standard practice to clarify that all appropriate inquiries and phase I environmental site assessments must include, within the scope of the investigation, an assessment of the real or potential occurrence of vapor migration and vapor releases on, at, in or to the subject property.

9 Assessment of Vapor Migration during Phase I ASTM E Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions, ASTM E specifically references ASTM 2600 (or another appropriate alternative methodology) to define vapor migration ASTM E does state nothing in this practice should be construed to require application of the Guide E2600 standard to achieve compliance with all appropriate inquiries. Other definitive and widely-accepted guidance is limited; E2600 is a common approach

10 Vapor Encroachment vs. Vapor Intrusion VE is commonly considered the migration of vapors into the vadose zone of a target property caused by the release of vapors from contaminated soil and/or groundwater either on or near the TP VI is commonly considered the migration of vapors from contaminated soils and/or groundwater into a structure

11 ? Encroachment

12 ASTM tier screening process to evaluate if a vapor encroachment condition (VEC) exists or does not exist Tier 1 identify the presence of known or suspected contaminated properties within an area of concern (AOC) n AOC = 1/3 mile for non petro and 1/10 mile for petro Tier 2 focuses on the characteristics of a plume and its proximity relative to a target property, is critical distance (CD) n CD = 100 feet for non petro/fp and 30 feet for petro

13 ASTM Recognized Environmental Condition (REC) is the presence or likely presence of any hazardous substances or petroleum products in, on, or at a property: (1) due to release to the environment; (2) under conditions indicative of a release to the environment; or (3) under conditions that pose a material threat of a future release to the environment. REC is not intended to include de minimis conditions (minor things) that generally do not present a material risk of harm to public health or the environment and that generally would not be the subject of an enforcement action if brought to the attention of appropriate government authorities. VE VI, but can be a REC VECs can be considered de minimis conditions that do not rise to the level of a REC Discussion for another day

14 Phase II Environmental Sampling So the VEC is a REC, and there is a possibility for VI, what next? EPA Guide Does not offer recommendations for VI assessments associated with real estate transactions Some points of the Guide may be relevant for due diligence sampling Many points cannot be accomplished within typical due diligence time lines Multiple rounds of sampling Develop a Phase II Sampling Scope based a conceptual site model (CSM) established from information gathered through the Phase I

15 CSM Source Media COC Extents Buildings Geology Pathways Population

16 VI Assessment Relying on multiple lines of evidence Groundwater n Sample at the top of groundwater table Soil n No soil impacts No vapor source Soil Gas n Sample soil gas above areas of soil source impacts n Near and/or below buildings n Near building samples as close as possible and below foundations Multiple locations ONLY TEST OF CONTAMINANTS REASONABLY KNOWN TO BE ASSOCIATED WITH RELEASE

17 VI Assessment continued Indoor Air LAST LOCATION TO TEST Time integrated for risk assessment (8hr for commercial/24hr residential) Removal of background sources difficult Document indoor/ambient sources through surveying

18 Preliminary Risk Screening EPAs Vapor Intrusion Screening Level Calculator Screening level for groundwater, soil gas, sub-slab soil gas, and indoor air using default exposure scenarios Allows for calculation of semi-site specific screening levels and/or candidate clean levels using user defined target risk levels, exposure scenarios, and various attenuation factors. VISL just one tool

19 Risk Thresholds EPA recommends assessing cumulative carcinogenic risk and non carcinogenic hazard, this is also the standard used by EPD Carcinogenic risk EPA prefers lowest (10-6), but often uses 10-5 EPD uses 10-5 Non carcinogenic hazard EPA/EPD uses HI 1

20 What Next? Risk < State Levels = No Further Assessment Warranted (today) Depending on source conditions may recommend preemptive mitigation Risk > State Levels Additional sampling and risk assessment (Jim) Mitigation (Ben)

21 Forbes, quote of the day (April Underwood): "I ve learned that asking questions isn t a sign of weakness; rather, it demonstrates curiosity, engagement and intelligence." Questions? Mr. Russell Griebel, P.G., C.P.G. rgriebel@unitedconsulting.com (678) THANK YOU!