conducting the vec investigation for a phase i - boston ddd

CONDUCTING THE VEC INVESTIGATION

FOR A PHASE I USING THE NEWLY

REVISED ASTM E2600 STANDARD

By:

Anthony J. Buonicore, P.E., BCEE, QEPCEO, The Buonicore GroupChairman, ASTM Vapor Intrusion Task Group

OVERVIEW▸ Background▹ Vapor intrusion vs. vapor encroachment▹ Why the concern?▹ Phase I and Vapor Migration▸ Conducting a VEC Screen▸ Making VEC-to-REC Determinations▸ Conclusions

WHAT IS VAPOR INTRUSION?

WHAT IS VAPOR ENCROACHMENT?

▸ Vapors released into the vadose zone of the TP from on-site and/or off-site contamination

▸ Off-site vapors must migrate across the boundary of the TP and “encroach upon” the vadose zone

▸ An example off-site source may be a nearby dry cleaner or gas station

▸ Vapor encroachment does not necessarily result in a vapor intrusion condition

▸ For a vapor intrusion condition to exist, vapors must not only be “encroaching” on the TP, but be able to migrate into structures on the TP and cause an indoor air quality problem

WHY SHOULD PROSPECTIVE PROPERTY OWNERS BE CONCERNED?

▸ Avoid potential future vapor migration/intrusion investigation costs after a property is acquired

▸ Eliminate concern about “closed” sites being re-opened (e.g., NY, MA, ME, CA, etc.)

▸ Eliminate anything that can potentially justify a tenant breaking a lease

▸ Avoid potential property stigma▸ Avoid potential future liability, including toxic tort

litigation, arising from tenant suits or other third party suits

ASTM E 1527 PHASE I STANDARD

▸ ASTM E1527-13 clarified that vapor migration is to be considered in Phase I investigations no differently than contaminated groundwater migration

▸ CERCLA/AAI do not differentiate by form (e.g., solid, liquid, vapor) of the release to the environment ▹ EPA in its December 30, 2013 AAI Amendment to

the Rule re-confirmed that the 2005 AAI Rule includes consideration of vapor migration

▸ Migrate/migration defined in E1527 to include vapor in the subsurface

▸ ASTM E2600 is a referenced document in E1527

CONDUCTING A TIER 1 VEC SCREEN

“Presence or likely presence of COC vapors in the subsurface of the TP caused by the release of vapors from contaminated soil or groundwater either on or near the TP”

VAPOR ENCROACHMENT CONDITION (VEC)

▸ Vapors must penetrate (“encroach upon”) TP boundary

▸ Vapors from on-site contamination have already penetrated TP subsurface (vadose zone)

CRITICAL DISTANCE ▸ Represents lineal distance COC vapors

volatilized from contaminated groundwater or contaminated soil might migrate in the vadose zone

▸ The distance is measured between the nearest edge of the contaminated plume (soil or groundwater) and the nearest TP boundary

▸ 100’ for COC Sources and Petroleum Hydrocarbon LNAPL sources

▸ 30’ for dissolved Petroleum Hydrocarbon sources

AREA OF CONCERN (AOC)

▸ Consists of the target property and the surrounding area, within which, if sources of volatile contamination are present, such contamination may produce vapors that can encroach upon the TP

▸ Measured from TP boundary to known or suspect contaminated property that is the source of volatile vapors (e.g., nearby dry cleaner)

▸ Default AOC vs. Adjusted AOC

DEFAULT AOC ▸ 1/3rd mile (1,760 ft.) for known or suspect

contaminated sites with COCs (volatile/semi-volatile hazardous substances)

▸ 1/10th mile (528 ft.) for known or suspect contaminated sites with Petroleum Hydrocarbon COCs

▸ Measured from TP boundary to known or suspect contaminated property

DETERMINING THE DEFAULT AOC

TP

Contaminated Plume

Length (?)

Vapor Migration Zone (100 ft)

Groundwater flow direction

Up-Gradient Source of Contamination

DETERMINING THE DEFAULT AOC

ADJUSTED AOC

▸ Default AOC may be adjusted based upon the EP’s professional judgment and experience with respect to local area conditions.

COMMON WAYS TO ADJUST THE AOC▸ Use knowledge of groundwater flow direction▸ Use local knowledge of subsurface

characteristics such as:▹ the presence of relatively impermeable soil or soil

layers, such as wet, fine-grained or highly organic soils – clay, silty-clay soils that retard vapor migration

▹ the presence of a perched water table (clean water above contaminated groundwater) – can reduce VI potential

▹ a very deep water table – can reduce groundwater contamination potential and therefore vapor migration

▹ fractured bedrock can increase VI potential

COMMON WAYS TO ADJUST THE AOC▸ Use knowledge of surface natural features such as:

▹ major water tributaries (rivers, etc.) that can intercept migrating vapors

▹ wetlands that can impede vapor migration▸ Use knowledge of man-made features such as:

▹ utility corridors under major roadways that can intercept migrating vapors and lead them away from TP (or toward TP)

▹ nearby buildings with characteristics that can impede vapor flow such as a building with well-ventilated multi-story underground parking below the building

COMMON WAYS TO ADJUST THE AOC▸ Use knowledge of the type target property or

planned development, and the local environment▹ on a relative basis, vapor migration represents a

greater concern for residential property (e.g., multifamily) than for industrial, office, hotel and retail property

▹ may want to be especially conservative in establishing the AOC for residential property

EXAMPLE: ADJUSTING THE AOC WHEN GROUNDWATER FLOW DIRECTION IS KNOWN OR CAN BE INFERRED

ADJUSTING THE AOC WHEN GROUNDWATER FLOW DIRECTION IS KNOWN OR CAN BE INFERRED

ADJUSTING THE AOC WHEN GROUNDWATER FLOW DIRECTION IS KNOWN OR CAN BE INFERRED

Up-gradient▸ 1,760 ft. (1/3rd

mile) for COC sources

▸ 528 ft. (1/10th mile) for Petroleum Hydrocarbon Sources

Down-gradient▸ 100’ COC

Sources/Petroleum Hydrocarbon LNAPL sources

▸ 30’ Dissolved Petroleum Hydrocarbon Sources

Cross-gradient▸ 100’ COC

Sources/Petroleum Hydrocarbon LNAPL sources plus Plume Width Consideration

▸ 30’ Dissolved Petroleum Hydrocarbon Sources plus Plume Width Consideration

ACCOUNTING FOR PLUME WIDTH FOR A CROSS-GRADIENT SOURCE UNDER A CONSERVATIVE SCENARIO WITH NO ACTUAL PLUME DATA*

▸ Assume worst case location for cross-gradient COC source, i.e., point of maximum plume width

▸ Assume plume width (Pw) can be estimated as 1/3rd of the 90th percentile plume length (Pl90)(supported by Domenico’s and Gelhar’s et. al. work; Newell et. Station LUST data; actual dry cleaner plume data and actual SHWS plume data)

* Buonicore, A.J., “Methodology for Identifying the Area of Concern Around a Property Potentially Impacted by Vapor Migration from Nearby Contaminated Sources,” Paper #2011-A-301, Proc. AWMA 104th Annual Conference, Orlando, FL, June 20-24, 2011

ADJUSTED AOC FOR TIER 1 SCREENING OF KNOWN OR SUSPECT COC SOURCES

Source Location

Up-gradient

Down-gradient

Cross-gradient

E 2600-15

1,760’

1,760’

1,760’

E 2600-15 w/ Suggested Methodology

1,760’

100’

365’

ADJUSTED AOC FOR TIER 1 SCREENING OF KNOWN OR SUSPECT PHC SOURCES

Source Location

Up-gradient

Down-gradient

Cross-gradient

E 2600-15

528’

528’

528’

E 2600-15 w/ Suggested Methodology

528’

100’ (LNAPL) 30’ (Dissolved)

165’ (LNAPL) 95’ (Dissolved)

TIER 1 SCREENING FOR VECs

▸ Tier 1 designed as a screening tool to preferentially be used in conjunction with a Phase I – relies on all the information already collected in Phase I investigation

▸ Tier 1 involves three steps:1. Starting with the Default AOC, determine if AOC can

be adjusted2. Identify known or suspected sources (e.g., dry

cleaner) of volatile vapors (“chemicals of concern” or “COCs”) within established AOC

Identify Known or Suspected Sources of COC Contamination: Phase I Government Records▸ Check the following databases for known or suspected

sources of COC contamination (TP and Established AOC)▸ NPL▸ CERCLIS▸ CORRACTS▸ Non-CORRACTS TSD▸ State Hazardous Waste Sites▸ Voluntary Cleanup Sites▸ Brownfield Sites▸ Landfills▸ LUST

PHASE I GOVERNMENT RECORDS cont’d

▸ Check the following TP records for potential COC releases or COC contamination (on TP)▸ Hazardous waste generation/storage ▸ Registered above- and below-ground

storage tanks▸ Reported spills▸ Mitigated on-site contamination managed

by Institutional/Engineering Controls (AULs)

IDENTIFY KNOWN OR SUSPECTED SOURCES OF COC CONTAMINATION: HISTORICAL RESEARCH

▸ Check for high liability former property uses on TP or in the established AOC with known or suspected COC contamination (such as dry cleaners, gas stations, manufactured gas plant sites, industrial sites, etc.)

MOST PREVALENT SOURCES OF CONCERN▸ Present and former gas station

sites▸ Present and former dry cleaner

sites▸ Present and former industrial sites,

particularly those using chlorinated solvents for degreasing and parts cleaning

▸ Former manufactured gas plant sites▸ Former hazardous waste disposal sites▸ Present and former garbage landfills

TIER 1 SCREENING FOR VECs cont’d

3) Make a VEC determination: - VEC exists, or

- VEC does not exist▸ When used in conjunction with a Phase I, if a VEC

exists, EP to determine if VEC represents a REC▸ If a VEC exists, user may also ask EP what further

investigation, if any, is warranted (such as proceeding to E2600-15 Tier 2 in order to obtain greater certainty about the VEC)

▸ If VEC does not exist, the investigation is ended (VI assumed to be a moot issue)

SUGGESTED APPROACH TO VEC SCREENING IN A PHASE I ESA

CONDUCTING A TIER 1 VEC SCREEN (ASSUMING NO PREFERENTIAL PATHWAYS)

1. Identify AOC and minimize to the maximum extent possible based on experience a. Start out with 1/3rd mile – 1/10th mile –

Default AOCb. Reduce Default AOC when GW flow direction

known or can be inferred (Adjusted AOC)

▸ Use professional judgment to reduce the AOC further▸ Hydraulic barriers (rivers, wetlands)▸ Sub-surface man-made physical barriers

(preventing vapors from reaching TP)▸ Utility lines in main roads (intercept vapors)▸ Low permeability soil in the sub-surface (impede

vapor movement)▸ Confining layers in the subsurface (low

permeability soil layer, fresh water lens – impede vapor movement)

CONDUCTING A TIER 1 VEC SCREEN (ASSUMING NO PREFERENTIAL PATHWAYS)


2. Are there any known or suspect COC contaminated sites in the established AOC?a. Government recordsb. Historical researchc. Other (?)

3. Evaluate any COC site(s) remaining in the established AOCa. Remediation status?b. Did remediation consider vapor pathway?c. Review AULs – contamination left on-site?d. Other (?)


4. Identify VEC statusa. Exists b. Does not exist

5. If VEC does not exist, vapor migration evaluation completed

6. If VEC exists, determine if VEC is a RECa. Rely on ASTM “De minimis” Criteriab. Rely on State VI Guidance Criteria c. Other (e.g., Federal VI Guidance, etc.)

7. If VEC is a REC, Tier 2 in E2600 offers a suggested scope-of-work for follow-up vapor investigation in a Phase II


PROFESSIONAL JUDGMENT FOR VEC-REC DETERMINATIONS

VEC-REC DETERMINATION: MAJOR CONSIDERATIONS

▸ State VI Guidance ▸ Typically identifies a distance between the nearest

edge of the contaminated groundwater plume and the nearest structure on the property – where VI may be a concern

▸ If distance not specified in State VI guidance, it is typical to rely on EPA VI Guidance (June 2015, p. 67, 100 ft.) or the ITRC Guidance (Jan. 2007, p.16, 100 ft.) or other (refer to E2600-15, Appendix 5)

▸ E1527 de minimus criteria (conditions that do not present material risk of harm to public health and the environment, and would not be subject to enforcement action by regulatory agency are not RECs)

▸ NJDEP VI Guidance – distance horizontally or vertically between the nearest edge of the contaminated groundwater plume and the nearest structure on the TP, equal to:▸ 100’ for COC or LNAPL PHC-COC▸ 30’ for Dissolved PHC-COC

FOR EXAMPLE…

FOR EXAMPLE…▸ PADEP VI Guidance – distance horizontally or

vertically between the nearest edge of the contaminated soil or groundwater plume and the nearest structure on the TP:

- Contaminated GW: 100’ horizontally

30’ uncontaminated sand

vertically above GW

15’ uncontaminated other soil

vertically above GW- Contaminated Soil: 100’

horizontally

10’ uncontaminated sand/soil

vertically between contaminated soil and building

REC EVALUATION▸ VEC may exist using E2600-15 Tier 1 criteria

because of groundwater contamination on or near the target property (TP), but a REC may not exist (under the ASTM de minimus condition clause) because the distance between the structure and the nearest edge of the contaminated plume may be greater than the distance specified in VI guidance document

KEY DISTANCES…▸ Building location on property (proximity to

contaminated plume with volatile vapors)▸ Distance from nearest building edge facing contamination

source to property line▸ Distance from property line to volatile vapor contamination

source

▸ No building on property, e.g., raw land or property not yet developed

▸ Distance from property line to volatile vapor contamination source

Assume State VI Guidance has actionable distance at 100’

Distance Downgradient Dry Cleaner’s Nearest Plume Edge to TP Boundary:

75’ Does VEC exist (use ASTM 100’ Criteria)?

Yes Distance TP Boundary to Nearest Bldg: 80’ Distance Nearest Plume Edge to Nearest Bldg:

155’ Does a REC exist (use State VI 100’ criteria)?

No

EXAMPLE

MA VI Guidance▸ First state to evaluate the vapor pathway - in 1993 MCP▸ In 2006, re-evaluated 600 closed PCE sites and 68 re-

opened▸ October 14, 2016 – most recent VI Guidance (for sites

regulated under 21E and the MCP) – for use by PRPs/LSPs▸ Focus is on conducting risk characterization for a site▸ “When VOCs are released to the subsurface near

occupied buildings and/or structures or migrate through the subsurface to the area around occupied buildings and/or structures, initiation of an assessment of vapor intrusion is required.” (Section 1.3)

MA VI Guidance cont’d

▸ Key distances: ▸ VOC in soil/soil gas adjacent to a building (6’

horizontally or 10’ vertically) – if Yes, go to CSM; if No, see GW classification

▸ Is GW classified as GW-2 (within 30’ of an occupied structure and less than or equal to 10’ vertically) – If Yes, compare concentrations to GW-2 standards: if exceed, go to CSM or if No or below, compare to 10x GW-2 standards within 100’ of occupied building and LNAPL within 30’ – if Yes, go to CSM; if No, determine if preferential pathways exist

▸ If no preferential pathways, no further evaluation of vapor pathway needed

▸ What is the contaminant concentration?For example, VEC may exist because of groundwater contamination on the TP or near the TP, but a REC may not exist (under the ASTM de minimus condition clause) because the contaminant concentration is below the risk screening level (RSL) in the State VI Guidance

OTHER CONSIDERATIONS

▸ What is the depth to contaminated groundwater?

For example, VEC may exist because of groundwater contamination on the TP or near the TP, but a REC may not exist (under the ASTM de minimus condition clause) because the depth to contaminated groundwater at the property may be greater than the applicable critical distance (100’ or 30’) or distances in the State VI Guidance.

OTHER CONSIDERATIONS

WHY IT MAKES SENSE TO USE E2600 TIER 1 AS THE PREFERRED METHODOLOGY TO EVALUATE VAPOR MIGRATION IN A PHASE I…

▸ E2600 methodology has been standardized through the ASTM consensus process

▸ Methodology was developed by industry experts▸ E2600 distances can be used without

documentation (other than referencing the E2600 standard)

▸ If an EP decides to use another methodology, E1527 requires sufficient documentation be included in the Phase I to permit reconstruction by a third party

▸ E2600 allows for professional judgment and experience (to adjust the AOC)

▸ Relying on E2600 reduces EP liability

THE BOTTOM LINE…▸ Vapor migration evaluation is a required part of a Phase I

investigation (no different than evaluation of contaminated groundwater migration)

▸ The only question for the EP is how to evaluate vapor migration

▸ E 2600-15 Tier 1 provides an industry consensus screening methodology

▸ EP can accept a Default AOC or modify the AOC (Adjusted AOC) consistent with professional judgment and experience

▸ Tier 1 is a cost effective screening methodology for use in a Phase I investigation

QUESTIONS?

conducting the vec investigation for a phase i - boston ddd

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