{"id":897512,"date":"2020-05-27T14:36:21","date_gmt":"2020-05-27T20:36:21","guid":{"rendered":"https:\/\/www.myconstructionexpert.com\/blog\/?p=897512"},"modified":"2020-05-27T14:36:25","modified_gmt":"2020-05-27T20:36:25","slug":"california-vapor-intrusion","status":"publish","type":"post","link":"https:\/\/www.myconstructionexpert.com\/blog\/california-vapor-intrusion\/","title":{"rendered":"California Issues Draft Guidance for Vapor Intrusion to Indoor Air"},"content":{"rendered":"\n

Brian Moskal | Greenberg Glusker<\/a><\/p>\n\n\n\n

California environmental agencies recently issued a draft vapor
intrusion<\/a> guidance document that will significantly impact the
investigation and remediation of environmentally impacted
properties by owners, operators and potential buyers.<\/p>\n\n\n\n

The guidance document will also impact real estate deals and
development involving those properties.<\/p>\n\n\n\n

The California State Water Resources Control Board, San Francisco
Regional Water Quality Control Board and California Department
of Toxic Substances Control released their \u201cDraft Supplemental
Guidance: Screening and Evaluating Vapor Intrusion\u201d for public
comment on Feb. 14.1<\/p>\n\n\n\n

The draft guidance attempts to standardize and render consistent
the approach that various California environmental agencies with
overlapping jurisdiction take regarding vapor intrusion.<\/p>\n\n\n\n

If promulgated in its current form, this guidance document could
make regulatory compliance for these properties significantly
more difficult, expensive and time-consuming.<\/p>\n\n\n\n

Real estate and environmental lawyers, property owners and
developers, and environmental consultants should accordingly
familiarize themselves with the draft guidance. They may also wish
to advise potentially affected clients of the likely implications and
the June 1 public comment deadline.<\/p>\n\n\n\n

BACKGROUND REGARDING VAPOR INTRUSION<\/p>\n\n\n\n

Vapor intrusion occurs when certain volatile chemicals released to
the ground or subsurface contaminate soil or groundwater. Gases
formed from the volatilization (i.e., evaporation) of these chemicals
can migrate up through soil and into buildings and homes via
basements, crawl spaces, cracks in foundations, sewer lines, gaps
around utility lines and other pathways.<\/p>\n\n\n\n

Chemicals that can cause vapor intrusion include trichloroethylene,
also referred to as TCE, and tetrachloroethylene, which is also
known as PCE. These solvents are commonly used by dry
cleaners and as industrial degreasers in manufacturing and metal
degreasing processes.<\/p>\n\n\n\n

arious agencies have identified them as carcinogenic or
potentially carcinogenic and harmful to human health in other
ways. Benzene, which is associated with releases of gasoline and
diesel fuel, is also volatile. It has been deemed carcinogenic and
can cause vapor intrusion.<\/p>\n\n\n\n

Historically, regulators were primarily concerned with subsurface
chemical impacts to groundwater that might be used as drinking
water or for other purposes. But some of that focus is now shifting
to vapor intrusion as health impacts from subsurface chemical
vapors, and their migration pathways into overlying buildings,
are better understood and testing equipment can measure ever-smaller concentrations.<\/p>\n\n\n\n

TCE in particular raises vapor intrusion concerns with regulatory
agencies. The U.S. Environmental Protection Agency and the
Department of Toxic Substances Control have issued guidance
documents indicating that even very low levels of TCE in indoor
air \u2014 as low as 2 micrograms per cubic meter for residential uses \u2014
may present an unacceptable risk to sensitive occupants such as
children, pregnant women, sick people and the elderly.<\/p>\n\n\n\n

These guidance documents state that these low levels can also
damage developing fetal hearts when pregnant women breathe
the impacted air.<\/p>\n\n\n\n

For perspective, 1 microgram per cubic meter is roughly equivalent
to a drop of liquid in five Olympic-sized swimming pools.<\/p>\n\n\n\n

Vapor intrusion problems may also be widespread. Properties
contaminated with chemicals that can volatilize into indoor air are
located throughout California and across the nation.<\/p>\n\n\n\n

Much of that contamination stems from historical business
operations as varied as electronics manufacturing, metal barrel
refurbishing and dry cleaning.<\/p>\n\n\n\n

Some of these operations date back more than a century, when
little was known about the potentially harmful health effects of
exposure to very low levels of these chemicals.<\/p>\n\n\n\n

In those early periods, it was common and often legal
to dispose of these chemicals and associated wastes
by discharging them into unlined ponds or even simply
discharging them onto the ground.<\/p>\n\n\n\n

Nevertheless, those companies may remain responsible
under environmental laws and sometimes lease provisions
to address their historical impacts to human health and the
environment. In many cases, the properties that are now
posing vapor intrusion risks were thought to be cleaned up.<\/p>\n\n\n\n

In fact, some of them have received a clean bill of health
from regulators. These historical impacts affect real estate
transactions when they are discovered by buyers during the
due diligence period.<\/p>\n\n\n\n

Addressing potential vapor intrusion issues at potentially
impacted properties can be complicated and expensive. It
generally begins with assessment work. This can entail testing
soil, soil gas and groundwater under and near buildings, and
indoor and ambient outdoor air to assess indoor air chemical
concentrations and to compare those concentrations with
outdoor air to rule out external sources.<\/p>\n\n\n\n

Contaminants in soil and groundwater that exceed regulatory
levels may need to be mitigated through measures such as
installation of vapor barriers on foundations, optimization
of heating, ventilation and air conditioning systems, or
construction of subslab depressurization systems to vent
vapors to the outdoor air.<\/p>\n\n\n\n

Contaminants may also need to be remediated through
elimination of the chemicals in the subsurface to reduce or
eliminate vapor intrusion problems.<\/p>\n\n\n\n

DRAFT GUIDANCE PROVISIONS<\/p>\n\n\n\n

The draft guidance includes four primary recommendations
for assessing possible vapor intrusion into buildings in
California.<\/p>\n\n\n\n

First, it recommends using attenuation factors the EPA
promulgated in 2015.<\/p>\n\n\n\n

Attenuation factors are multipliers used to extrapolate
chemical concentrations detected in subsurface soil gas
or groundwater to indoor air concentrations. A consultant
essentially takes the subsurface concentration and multiplies it by the attenuation factor. This calculation yields the
predicted indoor air concentration.<\/p>\n\n\n\n

For example, the draft guidance specifies a multiplier of 1
for crawl space chemical concentrations. This means the
guidance assumes 100% of the chemicals in the crawl space
intrude into indoor air \u2014 an assumption that some find
unrealistic.<\/p>\n\n\n\n

Similarly, the multiplier for groundwater is 0.001, meaning
it is assumed that 0.1% of the chemical in groundwater will
enter into indoor air.<\/p>\n\n\n\n

Some practitioners criticize this attenuation factor approach
as overly simplistic. Existing modeling can, in some cases,
use factors such as properties of the chemical at issue, soil
type and porosity, building age and size, and other factors
to develop a more nuanced, site-specific assessment of
indoor air. The draft guidance effectively rules out this kind of
modeling analysis.<\/p>\n\n\n\n

Second, the draft guidance recommends a four-step
evaluation process to determine whether a building located
near a known or suspected source of vapor-forming chemicals
may be affected by vapor intrusion.<\/p>\n\n\n\n

These steps are described on the following flowchart and
summarized below.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n

(1) Prioritize buildings in proximity to the source
contamination. First, determine whether there has been a
known or suspected release of vapor-forming chemicals. If
so, determine whether the release is associated with one or
more underground storage tanks, in which case the property
falls within the State Board\u2019s Underground Storage Tank
Low-Threat Closure Policy and not under the draft guidance.2
If not, the responsible party should evaluate whether acute
or short-term hazards are present based on the type or
concentrations of hazardous substances at issue. Such
hazards may require immediate mitigation or remediation
measures.<\/p>\n\n\n\n

According to the draft guidance, buildings within 100 feet of
the most contaminated areas or connected to a contaminated
area by a preferential pathway such as sewer lines, which are
discussed below, should be evaluated for vapor intrusion.<\/p>\n\n\n\n

The draft guidance also recommends skipping subsurface
sampling and proceeding directly to indoor air testing
for buildings that meet those criteria plus one of the
following: the release area is directly below the building; a
contaminated groundwater plume is near or less than 5 feet
below the building; or the building is connected to conduits
(such as sewer lines) that intersect significant subsurface
contamination.<\/p>\n\n\n\n

If the latter criteria are not met, then the guidance recommends
evaluating vapor intrusion using soil gas sampling instead of
indoor air testing, which is more consistent with the current
regulatory approach and is described in Step 2 below.<\/p>\n\n\n\n

(1) Collect exterior subsurface soil gas samples to determine
whether a building may experience vapor intrusion. If, based
on Step 1 above, it is appropriate under the draft guidance
to evaluate possible indoor vapor intrusion using soil gas
data instead of indoor air testing, the next step is to test
subsurface soil vapor chemical concentrations. The guidance
indicates the responsible party should conduct this testing
both near the building in question and laterally from the
suspected source area to determine the nature and extent of
the contaminant impact. The responsible party should also
sample at two or more depths, one depth above the known or
suspected source area and one or more shallower depths to
determine whether additional contamination exists.<\/p>\n\n\n\n

Next, the responsible party should calculate human health
risk using the 0.03 attenuation factor discussed above
applied to the maximum subsurface soil gas concentration.<\/p>\n\n\n\n

If the calculated cancer risk is greater than one in a million
or the hazard index, which is a measure of non-cancer health
effects, is greater than 1.0, then the responsible party should
conduct indoor air testing.<\/p>\n\n\n\n

If the calculated risk does not exceed either number, then the
draft guidance recommends repeating the soil gas testing
in a different season to account for seasonal variations in
subsurface chemical vapor concentrations.<\/p>\n\n\n\n

If the calculated risk remains below these numbers in a
different season, then the responsible party can consider it
a low vapor-intrusion priority building and regulatory closure
may be available.<\/p>\n\n\n\n

(1) Collect indoor air, subslab gas and outdoor air samples
if a building has vapor intrusion risk. If indoor air testing is
recommended based on Steps 1 or 2, then the responsible
party should survey the building. This includes locating and
removing indoor air sources of vapor-forming chemicals,
which can be more common than one may think, screening
for vapor entry points into the building, and observing the
surrounding area for possible outdoor sources of vapor-forming chemicals.<\/p>\n\n\n\n

Under the draft guidance, the responsible party should
select at least three indoor air sampling locations and three
co-located subslab sampling points, which will require
drilling through the floor and building foundation.<\/p>\n\n\n\n

These locations should be in primary live\/work spaces, near
slab or floor penetrations from which vapors may enter the
building and near the suspected maximum subsurface
contamination.<\/p>\n\n\n\n

In addition, the draft guidance recommends selecting three
outdoor locations upwind of the building to determine if any
indoor vapor concentrations may emanate from outdoor
sources rather than vapor intrusion.<\/p>\n\n\n\n

The guidance indicates the responsible party should then
estimate vapor intrusion risk using the maximum measured
indoor air concentration and estimate future vapor intrusion
risk using the maximum subslab gas concentration and an
attenuation factor of 0.03, as discussed above.<\/p>\n\n\n\n

The draft guidance also recommends conducting this testing
two to three times to account for seasonal variability, similar
to the repeated soil gas testing described in Step 2 above,
and once with the HVAC system on and once off.<\/p>\n\n\n\n

(1) Evaluate the need to manage current and future vapor
intrusion risk based on indoor air concentrations and
subsurface soil gas concentrations. If, based on Step 3,
cancer risk is greater than one in a million but less than one
in 10,000, and the calculated hazard index is less than 1.0,
then additional investigation, monitoring, risk assessment,
mitigation and remediation should be considered. If the
cancer risk is greater than one in 10,000 or the hazard index
is higher than 1.0, then mitigation and remediation should be
implemented.<\/p>\n\n\n\n

The third core element of the draft guidance is a
recommendation for increased consideration of sewers as a
potential vapor intrusion migration and exposure pathway.<\/p>\n\n\n\n

The agencies indicate subsurface vapors can enter sewer
lines that intersect contaminated soil vapor or groundwater
and be transported beneath or directly into buildings.<\/p>\n\n\n\n

Given this risk, the agencies recommend sampling indoor
air in a building that meets these criteria even if soil gas and
subslab sampling indicate no significant vapor intrusion risk
because they may ignore the sewer pathway risk.<\/p>\n\n\n\n

This could result in more complicated and expensive vapor
intrusion assessments because many buildings have sewer
lines beneath or connected to them that may intersect
contaminated soil or groundwater.<\/p>\n\n\n\n

All such buildings may be compelled under the draft
guidance to conduct indoor air sampling that would not be
required under existing guidance.<\/p>\n\n\n\n

Finally, the draft guidance lays the groundwork for
development of a California-specific vapor-intrusion database
of information such as vapor intrusion sampling and building
data. The purpose of this database is to understand how
human-caused and natural factors influence vapor intrusion.<\/p>\n\n\n\n

The information will be collected via the State Board\u2019s existing
GeoTracker database. A working group within the California
EPA will eventually use the database to determine whether
California-specific attenuation factors are appropriate in
place of, or in addition to, those discussed above.<\/p>\n\n\n\n

IMPLICATIONS OF THE DRAFT GUIDANCE<\/p>\n\n\n\n

The increased vapor intrusion sampling, mitigation and
remediation requirements set forth in the draft guidance
could increase the cost of vapor intrusion assessments by
as much as 30% to 60%, according to one environmental
consultant.3<\/p>\n\n\n\n

One reason is the increased emphasis on multiple lines of
evidence, such as soil gas, subslab, groundwater, and indoor
and outdoor air sampling. In addition, multiple sampling
events over a long period of time to evaluate seasonal
variations will increase the time and cost of assessment and
regulatory closure.<\/p>\n\n\n\n

These time frames will be completely unrealistic in many
real estate due diligence contexts, which may result in
creative approaches like environmental escrows, expanded
environmental indemnities and increased use of prophylactic
mitigation measures that may not ultimately be necessary.<\/p>\n\n\n\n

Collecting samples from multiple subsurface depths during
each sampling event will also increase complexity and costs.<\/p>\n\n\n\n

Finally, the required use of specified attenuation factors in
place of site-specific vapor-intrusion modeling will increase
the number of properties that exceed calculate cancer and
non-cancer risk thresholds.<\/p>\n\n\n\n

Due to the coronavirus pandemic, on March 25, the agencies
extended the public comment period until June 1 at noon.<\/p>\n\n\n\n

Comments can be submitted to DWQ-vaporintrusion@
waterboards.ca.gov. The agencies have indefinitely
postponed the public meetings previously scheduled for April
regarding the draft guidance.<\/p>\n\n\n\n

Property owners and developers, environmental and real
estate lawyers, environmental consultants and other
stakeholders in California should carefully evaluate the draft
guidance and submit public comments if they desire.<\/p>\n\n\n\n

Notes<\/p>\n\n\n\n

1 DTSC and California Water Resources Control Boards, Public Draft,
Supplemental Guidance: Screening and Evaluating Vapor Intrusion
(February 2020), available at https:\/\/bit.ly\/34U6DLi (last visited May 4,
2020).<\/p>\n\n\n\n

2 State Board, Underground Storage Tank Program, Low-Threat
Underground Storage Tank Closure Policy (last updated Sept. 3, 2019),
available at https:\/\/bit.ly\/2Kpq3OW (last visited May 4, 2020).<\/p>\n\n\n\n

3 Roux Associates, Inc., CA Vapor Intrusion Supplemental Guidance:
Notable Changes and Implications for Developers, Property Owners, and
Responsible Parties (Mar. 5, 2020), available at https:\/\/bit.ly\/2Vojmml
(last visited May 4, 2020).<\/p>\n","protected":false},"excerpt":{"rendered":"

Brian Moskal | Greenberg Glusker California environmental agencies recently issued a draft vaporintrusion guidance document that will significantly impact theinvestigation and remediation of environmentally impactedproperties by owners, operators and potential buyers. The guidance document will also impact real estate deals anddevelopment involving those properties. The California State Water Resources Control Board, San FranciscoRegional Water Quality… Continue reading California Issues Draft Guidance for Vapor Intrusion to Indoor Air<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[14],"tags":[9895,88,11175],"class_list":["post-897512","post","type-post","status-publish","format-standard","hentry","category-construction-2","tag-advise-consult","tag-california","tag-vapor-intrusion","entry"],"jetpack_publicize_connections":[],"yoast_head":"\nCalifornia Issues Draft Guidance for Vapor Intrusion to Indoor Air - 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