EvYglaxvd Interstate
Water Pollution Control
Commission
355 Balla.rdva.le Street
Wilmington
Massachusetts
01887
LUST.
Bulletin. 38
February
1998
A Report On Federal & State Programs To Control Leaking Underground Storage Tanks
nstihitioiial Consols
A Means to an End at LUST Sites
By Kevin Kratina
Institutional control mechanisms
have been used extensively through-
out the United States by federal,
state, and local governments to
'impose and document land- and
resource-use constraints that limit
human activities. These controls
serve as a means for protecting
human health and "welfare (e.g.,
hazardous and solid waste facil-
ity closure, notice of contami-
nated site) and in many
instances for preserving
and protecting the func-
tion of a resource (e.g.,
conservation area protec-
tion, aquifer protection,
historic preservation).
They include such
mechanisms as land-
use restrictions, struc-
ture-use restrictions,
well-restriction areas, deed restrictions, access controls, and
restrictive covenants (see sidebar). In all cases, control
requirements or notices must be recorded with the appropri-
ate regulatory agency(ies) so that anyone who needs to
uncover the existence of such a notice can find it.
Our experience over the past several years with risk-
based decision making, coupled with our need to undertake
protective, flexible, and common-sense remediations has, in
effect, opened the doors to the use of institutional controls at
sites managed throughout the New Jersey Site Remediation
Program. In a 1995 survey of LUST state program managers
conducted by the Association of State and Territorial Solid
Waste Management Officials (ASTSWMO), 14 of 27 respon-
dents acknowledged that they use institutional controls in
their site remediation procedures.
• continued on page 2
^^Direc^e/AMMlRJIAjStandard __
iAhi^lJEtr^^ffijHd^oJt?..-- _
iward Migration of Vapors
Integrity Assessment Update
MTBE and UST Compatibility
California Leak Detection Survey
What About Tank Lining?
New State MTBE Workgroup
Drinking Water Advisory
-------
LUSTLiitf Bulletin 28
I Institutional Controls from page 1
In New Jersey statute N.J.S.A.
58:10B 1, "institutional controls" are
defined as "a mechanism used to
limit human activities at or near a
contaminated site, or to ensure effec-
tiveness of the remedial action over
time when contaminants remain at a
contaminated site in levels or con-
centrations above the applicable
remediation standard that would
allow for unrestricted use of that
properly." New Jersey's institutional
controls may include, without
limitation, structure-, land-, and nat-
ural resource-use restrictions, well-
restriction areas, and deed notices.
A Bridge to Closure
Institutional controls have their
place in LUST site remediation and
closure. They can help bridge the
"how clean is clean?" gap by provid-
ing a means for closing a site sooner
rather than later. They can help
bridge a number of "what if?" con-
cerns regarding potential exposure
to soil contamination—What if
LUSTLine
i;
Ellen Frye, Editor
Ricki Pappo, Layout
Ivlarcel Moreau, Technical Advisor/Contributor^
""Ronald Poltak,titlWPCC Executive Director ;
; LynnDcPont, EPA Project Officer "^
Kate Becker, OUST LJaisort "
'~ WSTUne is a product of the New England
Interstate Water Pollution Control Commis-1
Environmental Protection Agency.
LUSTLine is issued as a communication
service for the Subtitle IRCRA
. Hazardous & Solid Waste Amendments
f rule promulgation process.
- LUSTLine is produced to promote ,
tnformntipn exchange on UST/ LUST issues.
The opinions and information stated herein '
art? those of the authors and do no necessar-
ily reflect the opinions of NEIWPCC.
This publication may be copied.
Please give credit to the NEIWPCC.
NEIWPCC was established by an Act of ""
Congress in 1947 and remains the oldest
agency in the Northeast United States ;
concerned with coordination of the multi-
media environmental activities
of the sta tes of Connecticut, Maine,
Massachusetts, New Hampshire,
New York, Rhode Island, and Vermont.
NEIWPCC
255 Ballardvale Street
Wilmington, MA 01887
Telephone: (978) 658-0500
FAX: (978) 658-5509
Iustline0neiwpcc.org
igy LUSTUne Is printed on Recycled Paper
TYPES OFlNSTiTUTldNALCdNfROLS
• Structure-Use Restrictions
|« Land-Use Restrictions
ft Natural Resource-Use Restrictions
',» Well-Restriction Areas
':• Deed Restrictions
!,,• Deed Notices
" Declaration of Environmental
t Restrictions
iP Access-Controls Monitoring °
; Requirements "
PB Site-Posting Requirements
r« Information Distribution ~, ., *
.• Notification in Closure Letter •
[" Restrictive Covenants
i - . t
l» Federal/State/County/Local Registries
someone drinks the water? What if
property use becomes residential
after a site has been closed? Institu-
tional controls can also provide reg-
ulators with a certain degree of
flexibility in making remedial deci-
sions that are both protective of pub-
lic health and the environment and
cost-effective.
It would be ideal if we could
return contaminated land and
groundwater to conditions that are
acceptable for unrestricted or resi-
dential use. At many petroleum
release sites, however, that goal is
prohibitive or may take many years
of relying on natural attenuation
processes; furthermore, that end-
point is not always warranted for a
host of reasons. As a result, the New
Jersey legislature has developed a
policy that provides for alternatives
to cleanups prescribed for residential
or unrestricted uses. Institutional
controls are an alternative that allows
a site to be closed, but only if specific
provisions are in place to protect
against potential exposure. An insti-
tutional control, for example, could
require that the approving agency be
notified prior to any land distur-
bance or land-use change that would
create an unacceptable exposure.
Technical and Philosophical
Reservations
Many institutional control issues are
hotly debated for both technical and
philosophical reasons. While no one
state's policy is the ideal model or is
completely transferable to another
state, in most states similar issues are
being debated in efforts to shape
institutional controls policy. Such
recurring themes include:
• Can residual levels of contami-
nation remain behind in soil
and groundwater and result in
no further impact on the envi-
ronment or exposure to recep-
tors if land and resource uses
don't change?
• Can a risk-based case closeout
be allowed without future
land-use constraints and/or
notifications?
• When natural attenuation pro-
cesses are deemed to be a pro-
tective and viable remediation
alternative, is it acceptable to
allow the remediation to be
ongoing for many years under
an institutional control rather
than require a more active
remediation process?
Certainly, states must consider
current and projected future land-
use pressures whenever contamina-
tion is allowed to remain in soil and
groundwater at levels that are unac-
ceptable for unrestricted use. Any
change in a current land-use scenario
(e.g., installation of a new drinking
water supply well, a new property
owner's plans for a residential devel-
opment, new subsurface structures,
utility worker exposure) has the
potential to change the institutional
control scenario.
Furthermore, while human
health is the primary consideration
in institutional-control decisions,
issues such as ecological impact, nat-
ural-resource restoration, natural-
resource damages, groundwater
ownership, prospective-purchaser
liability, property devaluation
(actual or perceived) on and off site,
a property owner's ability to use the
property as he or she chooses, and
the property owner's concurrence
with any restrictions or notices must
be factored into the debate as well.
Using Controls Effectively
Institutional controls are most effec-
tive when the regulatory agency
clearly defines its requirements for
-------
LUSTLine Bulletin 28
what levels of contamination can
remain at a site and under what con-
ditions, or "how dean is clean," based
on current land-use and exposure sce-
narios. This is particularly important
when the continued existence of such
"protective" conditions is beyond the
control of the regulatory agency.
Institutional controls should be
designed to remain protective over
time, especially when risk-based
remedial decisions are made based
on current land and resource use in
combination with prescriptive engi-
neering controls. These controls
should retained (i.e., "run") with the
land (e.g., in the form of deed
notices, use restrictions) or property
file, be filed with the appropriate
local/county/state land/resource-
use control agencies, and, as needed,
have affirmative obligations for
maintenance requirements that are
passed on to prospective pur-
chasers/operators/ site occupants.
Future land-use considerations
should be factored into the scope of a
remedial strategy early on in the
decision-making process. If property
purchasers are involved, the scope of
the remedial effort and the use of
any institutional controls should be
consistent with the purchaser's
intended property use. Prospective
property transactions may be
affected or become complicated by
the existence of contamination that
remains above levels that are accept-
able for unrestricted use, particularly
when liability is unclear or contami-
nation is not well defined.
Generating the data necessary
to define the "scope" of the institu-
tional control is a regulatory policy
decision. Once the scope is defined,
then we need data that support
stated goals. In evaluating what data
are necessary for a site, it is particu-
larly important to consider how
much field data will be needed ver-
sus how much to rely on the projec-
tions generated by a model.
Having an accurate basis for
determining the extent of contamina-
tion is especially meaningful in
instances when the institutional con-
trol (e.g., deed notice) requires con-
currence from the property owner.
Delineation in these circumstances
must be conducted so that the prop-
erty owner, purchaser, or neighbor-
ing property owner is able to use
his / her property in a manner he / she
Institutional controls can... provide \
^regulators with a certain degree of
LT flexibility in making remedial
idepisions that are both protective of
jfp'ublic health and the environment
and cost-effective. j
chooses, so that all parties are aware
of any impacts associated with
potential property values, and so
that there is concurrence with the
requested land-use restriction.
Questions of Public Policy
There are many public policy ques-
tions that must be considered in
designing a remedial program that
incorporates and relies upon the use
of institutional controls. Some of
these questions include:
• What land-use and population
pressures might lead to a
change in the exposure sce-
nario (e.g., industrial use to res-
idential use)?
• Should a state have penalty/
enforcement capability if the
site maintenance requirements
are not followed (e.g., should it
allow for breeches in exposure
control mechanisms)?
• Will a responsible party have
the option to place a "use
restriction" on property he or
she does not own? Will this
constraint be considered a "tak-
ing" of property?
• Should there be a preference
for permanent remedies that
are consistent with the National
Contingency Plan, and how
should the cost of the remedy
be considered?
• Will the repositories for the
institutional controls provide
reasonable notice to current
users, future purchasers, and
resource- and land-use decision
makers? Is there redundancy in
the multilevel notice require-
ments to prevent "system"
notification failure? Can the
diligent inquiry for such
notices be required in law at the
time of property transfer?
• Can the existing government
structure be used to record the
institutional control mecha-
nism? For example: Will a
county repository for deed
notices serve to provide notice
to future property purchasers?
• Will local officials be notified of
restrictions that may limit
property use in a manner that is
inconsistent with local zoning
plans?
• Should the institutional control
have an affirmative obligation
to allow site inspections?
Should this access be required
only if some form of "mainte-
nance" is required?
• What level of public notice
should be required?
• Is the ground water beneath a
given site considered state or
private party property? If the
site is located in a nonground-
water-use area, should all
property owners be notified?
• Should a state establish a mech-
anism to evaluate the effective-
ness of institutional controls
over time?
Institutional Controls in New
Jersey
Institutional controls are a crucial
tool in New Jersey's risk-based deci-
sion-making process. They build
flexibility into the closeout process
and provide protective and cost-
effective options to remediate sites.
Since the late 1980s, New Jersey has
used institutional controls in combi-
nation with engineering controls
(e.g., capping) that are designed to
eliminate exposure in some scenarios
as part of its remediation strategy. To
date, about 500 sites have been
issued conditional "no further
action" letters utilizing institutional
controls.
Legislation (P.L.1993, c!39)
passed in 1993 formally granted the
New Jersey Department of Environ-
mental Protection (NJDEP) the
authority to use institutional controls
when the remedy is protective of
human health and the environment.
As a result, persons conducting
cleanups in New Jersey have the
opportunity to utilize two primary
institutional control options, pro-
vided their sites meet certain criteria.
These options are:
• continued on page 4
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LUSTUne Bulletin 28
I Institutional Controlsyrom page 3
• Declaration of Environmental
Restriction (DER) - Used from
1993 through 1997 to record,
with county agencies, the pres-
ence of soil contamination
above residential-use criteria.
Per recent legislation, as of Jan-
uary 6,1998, the use of DERs is
no longer allowed. The mecha-
nism for recording the presence
of soil contamination is now a
deed notice. The deed notice
entails a more formalized filing
system for county agencies.
• Classification Exception Area
(CEA) Combined with a
Groundwater Well-Restriction
Area - Used to provide notifica-
tion to local, county, and state
agencies involved with well
installation/land use.
New Jersey allows soil contamina-
tion to remain at a site under the fol-
lowing conditions:
• When the contamination no
longer degrades groundwater;
• When soils do not represent a
direct contact threat to the cur-
rent use or when engineering
controls are in place to protect
the current use; and
• When the contamination will
no longer migrate.
The DER/deed notice option contains
an obligation on the part of the prop-
erty owner to maintain any engineer-
ing control and to notify the NJDEP of
any disturbances that could represent
an unacceptable exposure. If soil at a
site is remediated at the level that is
protective of an industrial-use sce-
nario and a new property owner
decides to redevelop the site as a resi-
dential property, the new owner or
the seller, possibly as a condition of
sale, would be required to
^notify the NJDEP of the
potential for expo-
sure. The site would
then require either
remediation to the
unrestricted resi-
dential criteria or
the incorporation
of engineering
controls to be
protective in a
residential-use
scenario.
To balance a risk-based remedi-
ation process with natural-resource
restoration, the CEA process for
groundwater requires remediation of
contaminant sources in the soil as
well as documentation of decreasing
trends in groundwater contamination
levels. Site-^spetific groundwater data
can be used to validate a model that
projects when the groundwater
contaminant will meet standards.
Once these "performance" criteria (as
opposed to a numeric standard) are
achieved, the case can be closed with
the CEA. As part of the CEA, the
extent of the plume must be docu-
mented.
i - Institutionalcontrols[aremost
effective when the regulatory agency
clearly defines its requirements for
what levels of contamination can
t remain at a site and under what ~
* conditions, or "howclean is clean," "^
' based on current land-use and
exposure scenarios.
To formally remove the CEA
designation, a sample from the
groundwater must be provided to
document compliance with the
groundwater standards. Removal of
the CEA designation in areas where
groundwater is not currently used
(based on a 25-year planning hori-
zon) is strictly voluntary.
The CEA is the single most
important institutional control
process in New Jersey's LUST reme-
diation program. Virtually all UST
remediations that have an impact on
groundwater will utilize this control.
The NJDEP has initiated an
inspection program to evaluate com-
pliance with the institutional/engi-
neering control practices. To date,
compliance rates have been approxi-
mately 90 percent. The inspections
have provided some helpful hints
regarding the implementation of
institutional controls. For example:
• If only a portion of a site has
been investigated or remedi-
ated, be sure that the notice
specifies what portions of the
site were or were not investi-
gated and remediated. That
there is no institutional control
on a particular site "subdivi-
sion" does not mean it is clean.
• Try to achieve consistent
recording procedures if multi-
ple agencies (e.g., counties,
municipalities) are involved in
the institutional control
process. For example, if a reg-
istry is used to record the
notices, the final notice of filing
should specifically reference
the page numbers where the
notice is recorded for easy
future reference. Also, be sure
filing documents are sized to
meet the criteria of the record-
ing agency. For example, over-
sized maps may represent a
filing/storage problem that can
result in lost maps or long
retrieval times. If deed notices
are used, be sure the notice is
not removed during the course
of transactions such as foreclo-
sures or subdivisions. One rea-
son the legislature opted for the
use of deed notices rather than
DERs was to ensure a more effi-
cient recordkeeping and
retrieval process.
• Consider inspection programs
to ensure compliance, possibly
on a 3- to 5-year schedule. Be
sure any legislation allows for
enforcement actions for non-
compliance (and possible elimi-
nation of any liability
protection for noncompliance)
as well as state inspector access
to these sites.
• Require a diligent inquiry or
search for the presence of any
notice during any property
transfer.
In short, in all situations where
institutional controls have been com-
bined with a "no further action" let-
ter in New Jersey, the full extent of
contamination has been defined,
controlled, and remediated to the
current use criteria. The results of the
initial institutional control inspec-
tions efforts have been favorable and
lessons learned will help us improve
on the existing program. •
Kevin Kratina is Chief of the Bureau of
Underground Storage Tanks at the
New Jersey Department of Environ-
mental Protection. He may be reached
at: kkratina@dep.state.nj.us.
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LUSTLine Bulletin 28
Investigation and Remediation
Natural Attenuation
EPA's New Policy Directive Vis a Vis ASTM's
New Industry Standard
by Matt Small and Hal White
Two guidance documents on "natural attenuation"
were completed in late 1997—EPA's OSWER
Directive titled Use Of Monitored Natural Attenua-
tion At Superfund, RCRA Corrective Action, And Under-
ground Storage Tank Sites and the American Society of
Testing Materials' (ASTM) standard of practice titled
Guide For Remediation Of Groundwater By Natural Attenu-
ation At Petroleum Release Sites. Although neither docu-
ment provides detailed technical guidance, they both
offer guidance on evaluating natural attenuation as an
appropriate remedial alternative.
The EPA directive is applicable to remediation of
contaminated soil and groundwater at sites regulated
under all programs administered by EPA's Office of Solid
Waste and Emergency Response (OSWER), including
Superfund, RCRA Corrective Action, and USTs. It is
intended to promote consistency in how monitored nat-
ural attenuation (MNA) remedies are proposed, evalu-
ated, and approved for protection of human health and
the environment. As a policy document, it provides guid-
ance to EPA and state staff, to the public, and to the regu-
lated community on how EPA intends to exercise its
discretion in implementing national policy on the use of
MNA.
The ASTM standard is a guide for determining the
appropriateness of remediation by natural attenuation
(RNA) and implementing RNA at petroleum release
sites. Its emphasis is on sites where groundwater is
impacted; it does not address situations where contami-
nated soil exists without an associated groundwater
impact. The standard describes a consistent, practical
approach to evaluating and utilizing natural attenua-
tion as a remedial alternative in an effort to reduce the
costs associated with cleanup of petroleum releases. As
an accepted industry code of practice, the standard is
intended to be used by environmental consultants,
industry, and federal, state, and local regulators
involved in response actions at petroleum release sites.
Naturally, there are some differences between the
two documents, but these are primarily in tone and
emphasis, reflecting the different perspectives and
responsibilities of the two entities that developed them.
On the whole, the two documents are consistent in their
approach to natural attenuation. EPA's policy, however,
presents a somewhat more cautious approach, espe-
cially in the areas of site characterization, source control,
performance monitoring, and contingency plans.
The ASTM document is an industry-consensus
standard and should be interpreted as the minimum
requirements for adequate demonstration that natural
attenuation is an appropriate remedial alternative for a
given site. Because EPA's directive represents official
regulatory policy, in cases where the two documents
are not in agreement, the EPA directive takes prece-
dence over the ASTM standard of practice.
The need for these documents is borne out by the
fact that there is little available published information
on natural attenuation and that this remedial alternative
is being used at thousands of sites nationwide. Scientific
understanding of natural attenuation processes contin-
ues to evolve rapidly, and significant advances have
been made in recent years. However, there is still a great
deal to be learned about the mechanisms governing
these processes and how they respond to different types
of contaminants and hydrogeologic environments.
Therefore, a natural attenuation remedy should be used
with caution commensurate with the uncertainty associ-
ated with a particular situation and only where it will
meet remedial objectives that are protective of human
health and the environment.
"Natural Attenuation"
The EPA directive distinguishes between "natural attenu-
ation processes" and "monitored natural attenuation" as
a remedial alternative. The "natural attenuation
processes" that are at work in this type of remediation
approach include a variety of physical, chemical, or bio-
logical processes that, under favorable conditions, act
without human intervention to reduce the mass, toxicity,
mobility, volume, or concentration of contaminants in soil
or groundwater. These in situ processes include biodegra-
dation, dispersion, dilution, sorption, volatilization,
chemical or biological stabilization, transformation, and
destruction of contaminants. -
The term "monitored natural attenuation" is defined
as "the reliance on natural attenuation processes (within
the context of a carefully controlled and monitored site
cleanup approach) to achieve site-specific remedial objec-
tives within a time frame that is reasonable compared to
that offered by other more active methods." Other terms
associated with natural attenuation, but not strictly
synonymous, include "intrinsic bioremediation," "intrin-
sic remediation," "passive bioremediation," "natural
recovery," and "natural assimilation."
• continued on page 6
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LUSTUne Bulletin 28
I Natural Attenuation from page 5
MONITORED NATURAL ATTENUATION =
"The reliance on natural attenuation processes (within the
context of a carefully controlled and monitored site cleanup
approach) to achieve site-specific remedial objectives within
a time frame that is reasonable compared to that offered
by other more active methods."
EPA OSWER Directive
While MNA is often dubbed "passive" remediation
because it occurs without human intervention, its use at a
site does not preclude the use of "active" remediation or
the application of enhancers of biological activity (e.g.,
electron acceptors, nutrients, and electron donors). How-
ever, by definition, a remedy that includes the introduc-
tion of an enhancer of any type is no longer considered to
be "natural" attenuation. Because the directive applies to
sites where contaminants other than petroleum con-
stituents (including some that are not biodegradable) may
be present, EPA uses the term "monitored natural attenu-
ation" throughout OSWER remediation pro-
grams unless a specific process (e.g.,
reductive dehalogenation) is being refer-
enced.
The ASTM RNA standard makes a dis-
tinction between the processes and remedial
action that is similar to EPA's directive.
Although the RNA definitions for "processes"
and "remediation action" sound somewhat
more broad, the ASTM standard applies only to
petroleum constituents in groundwater. Thus, the defini-
tions are actually more narrowly focused. "Natural atten-
uation" is defined in the RNA standard as "reduction in
mass or concentration of a compound in groundwater
over time or distance from the source of contamination
due to naturally occurring physical, chemical, and biolog-
ical processes." Remediation by natural attenuation is
defined as "a remedy where naturally occurring physical,
chemical, and biological processes will effectively achieve
remedial goals."
REMEDIATION BY NATURAL ATTENUATION =
"A remedy where naturally occurring physical, chemical, and
biological processes will effectively achieve remedial goals. "
ASTM Standard
CONTAMINANTS OF CONCERN AND
AFFECTED MEDIA
IHbSi The EPA directive is applicable to a wide variety
of sites and potentially unlimited combinations of conta-
minants and geologic media (including soil) as well as
groundwater. Many of the organic contaminants associ-
ated with petroleum products are biodegradable, but
some are not (e.g., MTBE). Some sites may have organic
solvents and other chemicals that are not associated with
petroleum fuels. Additionally, RCRA and Superfund
mixed-waste sites may have nonbiodegradable inorganic
contaminants, including metals and radionuclides. The
directive also points out that, in some cases, transforma-
tion products may present a greater risk than the parent
materials.
The ASTM RNA standard clearly states that its
emphasis is on the use of remediation by natural attenuation for
petroleum hydrocarbon constituents where groundwater is
impacted. It does not address situations where contaminated
soil exists without an associated groundwater impact. It also
states that while much of what is discussed is relevant to other
organic contaminants, these situations will involve additional
considerations that are not addressed in the guide. The guide
emphasizes that care must be taken to ensure that degradation
byproducts will not cause harm to human health or the envi-
ronment. Furthermore, if compounds are present that do not
readily attenuate (e.g., MTBE), RNA may not be a suitable
remedial alternative or may need to be supplemented with other
remedial technologies.
REMEDY SELECTION CRITERIA
I3ju9 EPA does not consider MNA to be a "presump-
tive" or "default" remedy; rather the agency advocates
using the most appropriate technology for a given site.
Determination of the most appropriate technology
requires that it meet the applicable statutory and regula-
tory requirements, that it be fully protective of human
health and the environment, and that it meet site remedi-
ation objectives within a time frame that is reasonable
compared with that offered by other methods.
In general, EPA anticipates that MNA will be used
as one component of the total remedy—either in conjunc-
tion with active remediation or as a follow-up measure to
active remediation—and more rarely as the sole remedy
at contaminated sites. Selection of MNA as a remediation
method should be supported by detailed site-specific
information that demonstrates the efficacy of this remedi-
ation approach, including comprehensive site characteri-
zation, source control, performance monitoring, and
contingency remedies (where appropriate).
The ASTM standard specifies that RNA is a reme-
dial action approach that is compatible with existing remedy
selection processes but should not generally be considered a pre-
sumptive remedy. RNA is not exclusive of other options and
should be evaluated in the same manner as other remedial
action options for a site. Remedial options should be selected
based on their potential to achieve remedial goals.
Several actions are necessary to determine whether RNA
is an appropriate remedial alternative, including site character-
ization, assessment of potential risks, and evaluation of poten-
tial effectiveness similar to other remedial action technologies.
The standard explicitly recognizes that there are situations
where it is either not necessary or cost-effective to expend
resources (e.g., time, money) to undertake a more aggressive
approach to remediation.
RNA may be used as a stand-alone option for meeting
remedial goals within groundwater if the potential for a near-
term impact to an existing receptor is determined to be low.
However, if risk-management strategies are not sufficient to
-------
LUSTLine 'Bulletin 28
prevent impacts to an identified receptor, then remediation by
natural attenuation is inappropriate as a stand-alone option.
^- Due to the uncertainty of the effectiveness of natural
attenuation, both documents recommend that contin-
gency remedies be identified for implementation should
natural attenuation fail to meet remediation objectives.
SITE CHARACTERIZATION
IHjuH EPA requires that decisions to employ monitored
natural attenuation as a remedy or remedy component
should be thoroughly and adequately supported with
site-specific characterization data and analysis. Site char-
acterizations for natural attenuation generally warrant a
quantitative understanding of source mass; groundwater
flow; contaminant-phase distribution and partitioning
between soil, groundwater, and soil gas; rates of biologi-
cal and nonbiological transformation; and the variation of
all these factors with time. This information is generally
necessary because contaminant behavior is governed by
dynamic processes that must be well understood before
natural attenuation can be applied appropriately at a site.
From this site characterization information, a con-
ceptual model, which provides the basis for assessing
potential remedial technologies at a site, can be devel-
oped. A conceptual site model is a three-dimensional rep-
resentation, which may vary over time, that conveys what
is known or suspected about contamination sources,
release mechanisms, and the transport and fate of those
contaminants.
In general, the level of site characterization neces-
sary to support a comprehensive evaluation of MNA is
more detailed than that needed to support active remedi-
ation. The EPA directive provides a couple of examples
where, because of site complexity, MNA may not be an
appropriate remedy (e.g., where technological limitations
may preclude adequate monitoring or the determination
of the pathways of groundwater flow).
The ASTM RNA standard states that site characteri-
zation must provide the user with adequate information to
determine if RNA is a viable remedial option for the site, either
by itself or in conjunction with other technologies. Information
on site assessment techniques is referenced in other ASTM
guides. Because the RNA standard is applicable only to ground-
water contamination, the implementation of RNA requires ade-
quate definition of the groundwater plume and understanding
of site hydrogeology. The lack of necessary site data or the
inability to obtain representative or otherwise requisite samples
necessary to construct an acceptable site conceptual model (e.g.,
aquifer parameters, groundwater and soil chemistry) can pre-
clude appropriate implementation of RNA.
Specific types of site characterization information that
may be necessary to support RNA are listed in an appendix and
include lines of evidence (discussed in next section), details
about the release, regional and site hydrogeology, locations of
nearby receptors, contaminant concentrations, and extent of
contamination. The ASTM standard states that technical limi-
tations may obstruct the implementation or progress of RNA
and require the consideration or use of other remediation alter-
natives. Such limitations can include constraints associated
with inadequate data used to construct the site conceptual
model, the inability to implement the monitoring program,
insufficient data to perform predictive modeling, and changes
in site conditions.
^ EPA's directive differs from the RNA standard in that
it conveys the unequivocal message that site characteriza-
tions for remedies that propose to use natural attenuation
should be necessarily more detailed than those for active
remediation technologies.
EVIDENCE OF NATURAL ATTENUATION
iHibdl The EPA directive outlines three lines of evidence
that can be used to evaluate the efficacy of MNA as a
remedial approach:
1. Historical groundwater and /or soil chemistry data
that demonstrate a clear and meaningful trend of
decreasing contaminant mass and /or concentration
over time at appropriate monitoring or sampling
points;
2. Hydrogeologic and geochemical data that demon-
strate the types and rates of natural attenuation
processes active at the site; and
3. Data from field or microcosm studies conducted
with contaminated site material that demonstrate
the occurrence of biological degradation processes
(for biodegradable components only).
Unless EPA or the implementing agency determines
that evidence from item #1 is sufficient to support a deci-
sion that the use of MNA is appropriate, then evidence
from item #2 should be provided. Evidence from item #3
is generally required when evidence from items #1 and #2
is inadequate or inconclusive.
Where contaminants are not readily degraded
through biological processes, where toxic and/or mobile
transformation products are formed, or where ground-
water and soil chemistry data have been collected for
only a short time, more supporting
information may be required. It is
the responsibility of the regulatee •
to provide the evidential data to
EPA or the appropriate implementing *. . '
agency.
The RNA standard defines its
three lines of evidence as follows:
1. Observed reductions in concentrations of the compounds
of concern in the field (the primary line of evidence for
RNA);
2. Geochemical indicators of naturally occurring degrada-
tion and estimates of attenuation rates (secondary line of
evidence); and
3. Microbiological information and more sophisticated
analysis of primary and secondary lines of evidence such
as modeling or estimates of assimilative capacity (addi-
tional optional lines of evidence).
The first line of evidence is the primary line of evidence
and is required to demonstrate RNA. The decision to collect
secondary and 'optional lines of evidence should be based on the
intended use of the data. The cost benefit of obtaining these
• continued on page 8
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LUSTLinc Bulletin 28
I Natural Attenuation from page 7
lines of evidence should also be considered. The primary lines of
evidence include concentration data for the compounds of con-
cern at the site, used to define the plume as shrinking, stable, or
expanding. For sites where there are sufficient historical moni-
toring data, the primary lines of evidence will often be adequate
to demonstrate RNA.
As for secondary lines of evidence, the standard states
that if the primary lines of evidence are inconclusive, it may be
necessary to obtain secondary lines of evidence. For those sites
where assessment and data collection efforts have recently been
initiated, it may be appropriate to supplement the primary lines
of evidence with geochemical indicator data. The primary line of
evidence is still required at these sites and must be built
through data collection over time.
^- Thus, both documents outline three essentially identi-
cal lines of evidence, but EPA's directive promotes collec-
tion of first and second lines of evidence as a general rule,
while the RNA standard requires the first line of evidence
to demonstrate natural attenuation.
GROUNDWATER PLUME STATUS
Euul The EPA directive addresses the issue of plume
status by noting that MNA would more likely be appro-
priate if the plume is not expanding nor threatening
downgradient wells or surface water bodies. MNA
should not be used where significant contaminant migra-
tion or unacceptable impacts to receptors would result.
The most appropriate candidate sites for MNA remedies
are those where contaminant plumes are no longer
increasing in size or are shrinking in size.
The ASTM standard requires that the dissolved
petroleum plume be categorized as shrinking, stable, or expand-
ing based on historical contaminant concentrations (first line of
evidence) obtained from monitoring wells. For sites where there
are sufficient historical monitoring data, the primary lines of
evidence will often be adequate to demonstrate RNA. A mini-
mum of four monitoring events will likely be required to evalu-
ate the plume status.
The standard explains that it may be necessary to obtain
additional monitoring data before a plume can be defined as sta-
ble or shrinking and outlines the implications of the three plume
categories as follows:
1. A shrinking plume is evidence of natural attenuation;
2. A stable plume is evidence of natural attenuation; and
3. In the case of an expanding plume, the contaminant mass
loading rate to groundivater exceeds the natural attenua-
tion rate. It is important to continue to monitor the
expanding plume.
With regard to RNA as an appropriate remedy, the per-
formance of RNA is generally acceptable if a plume is shrinking
or stable (primary line of evidence) and there are no impacts to
receptors. If a plume is expanding but at a rate lower than the
groundwater velocity, the risk reduction and performance goals
may be met depending on the presence and location of receptors.
^- At first glance, both documents seem to be in harmony
on this issue. However, there is potentially significant
divergence in two areas. First, the RNA
standard states that natural attenuation
is occurring where a plume is shrink-
ing or stable. However, RNA may
be appropriate at sites where the
plume is shrinking, stable, or
expanding, as long as the
requirements for no receptor impacts are met, as discussed
earlier. EPA's directive takes a somewhat more cautious
position in recommending that monitored natural attenua-
tion may be appropriate where a plume is shrinking or no
longer expanding. The difference between these two condi-
tions is EPA's implicit assumption that where a plume is
no longer expanding, it is shrinking. When a plume is sta-
ble, there is the implication that the source is continuous,
which is usually unacceptable from a regulatory perspec-
tive.
Second, the RNA standard states that it is important
to continue to monitor an expanding plume. This
approach allows for application of RNA at sites where it
is anticipated that the plume will stabilize within limits
that are appropriate for risk management and will even-
tually begin to shrink. From the EPA MNA directive per-
spective, an expanding plume indicates that natural
attenuation is not effective and that a more aggressive
remediation technology (the "contingency remedy")
should be implemented.
REMEDIATION TIME FRAME
Bu9 The EPA directive recognizes that defining a rea-
sonable time frame for achieving remediation objectives
is a complex and site-specific decision and that, in gen-
eral, time frames are longer for MNA than for active
remediation technologies. Additionally, because of these
extended time frames, hydrogeologic conditions and
plume behavior can also change. Factors that influence
the determination of what is a reasonable time frame
include:
• The relative time frame in which affected portions
of an aquifer are needed for future water supplies;
• The classification and value of affected resource(s);
• Uncertainties in the data, assumptions, and predic-
tive analyses (e.g., travel time for contaminants to
reach receptors);
• Reliability of monitoring and institutional controls;
and
• Public acceptance of the extended time for remedia-
tion.
In addition, state groundwater protection programs
should be consulted for guidance and requirements. A
careful analysis of such factors should enable an environ-
mental agency to determine whether a MNA remedy will
fully protect potential human and environmental recep-
tors and whether site remediation objectives and the time
needed to meet them are acceptable. When these condi-
tions cannot be met using MNA, a remedial alternative
that does meet them should be selected instead.
The RNA standard also recognizes that time frames
for achieving remedial goals can be relatively long. A long
8
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LUSTLine Bulletin 28
period of time may be required to remediate heavier petroleum
products. RNA may take longer to mitigate contamination than
more aggressive remedial measures do. Thus, RNA may not
always achieve the desired cleanup levels within a manageable
time frame. The longer time frame, therefore, may require the
use of institutional controls to manage and prevent exposures.
If, on the other hand, RNA is likely to meet the remedial
goals within the desired time frame, then it is a viable alterna-
tive. However, if the probability of RNA meeting remedial goals
is low or uncertain, then supplementary or alternative remedial
action measures may be appropriate. The time frame for achiev-
ing remedial goals is an important criterion for comparison of
RNA with other remedial options. The standard cautions that
care should be exercised in estimating remediation time frames
for other remedial options so as to not bias the comparison with
overly optimistic representations of cleanup time frames.
^ There is essentially no difference between the EPA
directive and ASTM's standard on this issue. Both
acknowledge potentially extended time periods for nat-
ural attenuation to meet remediation objectives as well as
potential need for more aggressive ("contingency") reme-
dies should natural attenuation fail to meet reme-
diation objectives within a reasonable (or
"manageable") time frame.
SOURCE CONTROL
Hir»» EPA expects that source control
measures will be evaluated for all sites
under consideration for any proposed
remedy, especially where MNA is under
consideration as the remedy or as a remedy
component. The need for such evaluation is largely a
reflection of the uncertainty associated with the potential
effectiveness of MNA to meet remedial objectives that are
protective of human health and the environment within a
reasonable time frame.
Source control measures include removal, treat-
ment, or containment measures (e.g., physical or
hydraulic control of areas of the plume in which NAPLs
are present in the subsurface). EPA prefers remedial
options that remove or treat contaminant sources when
such options are technically feasible. The need for source
control is clear—contaminant sources that are not ade-
quately addressed complicate the long-term cleanup
effort by leaching significant quantities of contaminants
into the groundwater, which can extend the time neces-
sary to reach remedial objectives.
EPA believes that control of source materials is the
most effective means of ensuring the timely attainment of
remediation objectives. Following source control mea-
sures, monitored natural attenuation may be sufficiently
effective to achieve remediation objectives at some sites
without the aid of other (active) remedial measures. Typi-
cally, however, monitored natural attenuation will be
used in conjunction with active remediation measures
even at petroleum release sites.
The ASTM standard states that an evaluation of the
need for source area control measures should be integrated into
remedial decision-making at all sites where RNA is under con-
sideration. Source area control measures include physical
removal, treatment, and stabilization. The standard acknowl-
edges that the RNA option is subject to approval by the regula-
tory agency responsible for the oversight of the cleanup of the
petroleum release and source area control decisions.
^ Perhaps the most significant difference between EPA's
directive and ASTM's standard is EPA's emphasis on the
need for source control (including free product recovery).
Federal regulations (specifically 40 CFR 280.64), which
are acknowledged by the ASTM standard, require that
free product be recovered to the maximum extent practi-
cable as determined by the implementing agency. EPA's
directive advocates source control measures in all cases,
but especially when employing natural attenuation, so
that remediation time frames are not unacceptably
extended. EPA also expresses a preference for source con-
trol measures that remove or treat sources rather than
merely contain them.
PERFORMANCE MONITORING
LHjLifl The EPA directive includes the term "monitored"
when referring to a remedy that utilizes natural attenua-
tion processes to emphasize that this is not a "do-noth-
ing" or "walk-away" remedial option—long-term
performance monitoring is an essential component of
MNA and any other remedial option. Use of MNA does
not imply that activities (and costs) associated with inves-
tigating the site or selecting the remedy (including perfor-
mance monitoring) have been eliminated. These elements
of the investigation and cleanup must still be addressed
as required under the particular OSWER program,
regardless of the remedial approach selected.
MNA will not generally be appropriate where site
complexities preclude adequate monitoring or in cases
where the associated costs are high compared with the
cost of active remediation technologies. While perfor-
mance monitoring to evaluate the effectiveness of a rem-
edy and to ensure protection of human health and the
environment is a critical element of all response actions, it
is of even greater importance for MNA because of its
longer remediation time frames, potential for ongoing
contaminant migration, and other uncertainties.
The monitoring program developed for each site
should specify the location, frequency, and type of sam-
ples and measurements necessary to evaluate remedy
performance as well as define the anticipated perfor-
mance objectives of the remedy. In addition to verifying
the attainment of cleanup objectives, an adequate moni-
toring program should identify any potentially toxic
transformation products resulting from biodegradation,
determine if a plume is expanding (either downgradient,
laterally or vertically), ensure adequate warning of poten-
tial impact to downgradient receptors, detect new
releases of contaminants to the environment that could
have an impact on the effectiveness of the natural attenu-
ation remedy, demonstrate the efficacy of institutional
controls that were put in place to protect potential recep-
tors, and detect changes in environmental conditions
(e.g., hydrogeologic, geochemical, microbiological, or
other changes) that may reduce the efficacy of any of the
natural attenuation processes.
• continued on page 10
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UlSTLine Bulletin 28
\ Natural Attenuation from page 9
Typically, performance monitoring is continued for
a specified period (e.g., 1 to 3 years) after cleanup levels
have been achieved to ensure that concentration levels are
stable and remain below target levels. The institutional
and financial mechanisms for maintaining the monitoring
program should be dearly established in the remedy deci-
sion or other site documents, as appropriate.
P^yiili The ASTM standard acknowledges that implemen-
tation ofRNA requires demonstration of remedial progress and
attainment of remedial goals through monitoring. The inability
to obtain representative or otherwise requisite samples neces-
sary to design an adequate long-term monitoring plan can pre-
clude appropriate implementation ofRNA. According to the
standard, once an RNA option is selected, it is necessary to
develop and implement a monitoring program that is both capa-
ble of yielding adequate information to evaluate the progress of
RNA in meeting remedial goals and cost-effective.
The cost associated loith monitoring may well be the most
expensive part of a natural remediation project. The objectives
of the monitoring program are defined as:
• Evaluating performance and progress of RNA toward
meeting remedial goals, and
• Ensuring that the plume is not migrating to an extent
greater than expected.
The standard states that the monitoring program should
include appropriate sampling locations, adequate sampling fre-
quency, and meaningful sampling parameters and that it
should include sufficient groundwater monitoring wells, both
in number and location, to determine changes in groundwater
flow directions and velocities, trends in contaminant concentra-
tions within the plume (over time and/or distance), and any
further migration of the plume.
According to the standard, although monitoring fre-
quency is a site-specific consideration, it should be at least quar-
terly for a minimum of 1 year so as to define seasonal
fluctuations in contaminant concentrations, water table eleva-
tions, and hydraulic gradients. The lack of these data could
make it very difficult or impossible to adequately resolve con-
centration trends in subsequent data sets.
Wliere variability in concentration of the compounds of
concern precludes the resolution of any trends, or if monitoring
data do not indicate significant natural attenuation, then the
standard recommends that geochemical indicator parameters be
evaluated in addition to the primary line of evidence. Monitor-
ing results should be evaluated to determine progress toward
meeting remedial goals.
If remedial goals are met, then no further action is
required. If remedial goals are not met, RNA remedial progress
should continue to be evaluated. When remedial goals have been
achieved, and further monitoring is no longer required to
ensure that conditions persist, then no further action is neces-
sary, except to ensure that institutional controls (if any) remain
in place, and regulatory concurrence should be pursued.
^ There are no major differences with regards to perfor-
mance monitoring. However, EPA cautions that monitor-
ing generally should continue for 1 to 3 years after
cleanup levels have been achieved to ensure that concen-
tration levels are stable and remain below target levels.
REMEDIATION OBJECTIVES
LajLifl EPA has responsibility for establishing site-spe-
cific remediation objectives that are fully protective of
human health and the environment. In the EPA directive,
remediation objectives are defined as the overall objec-
tives that remedial actions are intended to accomplish
and are not the same as chemical-specific cleanup levels.
Remediation objectives could include preventing expo-
sure to contaminants, minimizing further migration of
contaminants from source areas, minimizing further
migration of the groundwater contaminant plume, reduc-
ing contamination in soil or groundwater to specified
cleanup levels appropriate for current or potential future
uses, and other goals. EPA supports the use of risk-based
decision-making in establishing remedial goals for UST
corrective actions (OSWER Directive 9610.17).
The ASTM standard advocates that remedial goals
be determined by applying the risk-based corrective action
process in [ASTM] Guide E 1739 or another state-approved
method. Remedial goals established to protect human health
and the environment may take the form of concentration target
levels at specific points or performance criteria, such as demon-
stration that the petroleum hydrocarbon plume has been con-
tained. Remedial goals may also have some time frame
associated with them.
In general, the ASTM risk-based approach requires that
the potential for impacts to human health and the environment
be determined by conducting surveys of primary and secondary
sources, transport mechanisms, viable exposure pathways, and
potential receptors. Target levels must be either an achievable
numeric value or other performance criteria that protect human
health, safety, and the environment.
In general, RNA is more amenable to achieving perfor-
mance-based goals, such as demonstrated containment of the
groundwater plume or demonstrated reduction in contaminant
concentrations over time within the plume or with distance
from the source area.
^- Both documents are in harmony with regard to reme-
diation objectives. However, the ASTM standard defines
remedial goals that are applicable only to UST release
sites, while EPA's directive is designed for a broader class
of contaminated sites.
CONTINGENCY REMEDIES
l"lira» EPA recommends that remedies employing moni-
tored natural attenuation be evaluated to determine the
need for including one or more contingency measures
that would be capable of achieving remediation objec-
tives. EPA believes that a contingency measure may be
particularly appropriate for a monitored natural attenua-
tion remedy that has been selected based primarily on
predictive analysis (the second and third lines of evi-
dence discussed previously) as compared with natural
attenuation remedies based on historical trends of actual
monitoring data (the first line of evidence).
According to the directive, contingency remedies
should be employed where the selected technology is not
proven for a specific site application, where there is sig-
nificant uncertainty regarding the nature and extent of
10
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LUSTLine Bulletin 28
the contamination at the time the remedy is selected, or
where there is uncertainty regarding whether a proven
technology will perform as anticipated under the particu-
lar circumstances of the site.
Criteria that may trigger implementation of the con-
tingency remedy include:
• An increasing trend in contaminant concentrations
in either groundwater or soil at sampling locations;
• Evidence of a new or renewed release;
• Discovery of contaminants in sentry/sentinel wells
located outside of the original plume boundary
(indicating renewed contaminant migration);
• Contaminant concentrations that are not decreasing
at a sufficiently rapid rate to meet the remediation
objectives; and
• Changes in land and/or groundwater use that will
adversely affect the protectiveness of the monitored
natural attenuation remedy.
The RNA standard states that if it is shown that
RNA is not solely sufficient to provide adequate protection of
potential receptors, the data collected for the RNA study can be
used to design supplemental remedial alter natives. If remedial
progress does not match estimates, RNA should be reevaluated
as to whether it is an appropriate remediation option for the site.
If at any point during the long-term monitoring program, data
indicate that natural attenuation is not adequate to contain the
plume, the contingency plan should be implemented.
^ Again, there are no major conflicts between EPA's
directive and ASTM's standard. The EPA directive is
somewhat more adamant about the need for considering
contingency remedies at the beginning of the site evalua-
tion process rather than later, when it may be too late for
the contingency remedy to be protective of human health
and the environment.
NO FURTHER ACTION
atmM The EPA directive recommends that performance
monitoring should continue as long as contamination
concentrations exceed the required cleanup levels. It rec-
ommends that performance monitoring be continued for
a specified period (e.g., 1 to 3 years) after cleanup levels
have been achieved to ensure that concentration levels are
stable and remain below target levels. It also recommends
that institutional and financial mechanisms for maintain-
ing the monitoring program be clearly established in the
remedy decision or other site documents, as appropriate.
The ASTM standard states that when it can be
demonstrated that target cleanup levels or performance-based
criteria for a site have been achieved, and further monitoring is
no longer required to ensure that conditions persist, then no
further action is necessary. Mechanisms or procedures must be
implemented to ensure that institutional controls (if any)
remain in place. Regulatory concurrence should be pursued on
a determination of no further action.
The ASTM standard lists four key criteria for no further
action at a site that has undergone remediation by natural
attenuation:
• There are no existing or potential receptor impacts;
• Remedial goals have been met, or it has been demon-
strated that natural attenuation will continue and ulti-
mately meet remedial goals;
• The plume is stable or shrinking; and
• If needed, institutional controls are in place and main-
tained.
If natural attenuation is demonstrated to be effective at a
site, and site conditions will not change, natural attenuation
will continue to serve as an ongoing remedial action regardless
of whether it is monitored.
^ Both documents recommend that monitoring be con-
tinued to ensure that conditions persist. However, the
ASTM standard allows for a determination of no further
action prior to actually meeting remedial goals if it has
been demonstrated that natural attenuation will continue
and ultimately meet remedial goals. This idea means that,
in some cases, the implementing agency could approve
termination of monitoring before remedial goals are met.
The EPA MNA directive takes a more conservative
approach, recommending that performance monitoring
continue as long as contamination concentrations exceed
the required cleanup levels. Once cleanup levels are met,
the directive recommends additional monitoring to
ensure that conditions persist. ( See chart on page 12.)
To Obtain the Standards...
The EPA OSWER directive, Use of
Monitored Natural Attenuation at
Superfund, RCRA Corrective Action,
and Underground Storage Tank Sites,
OSWER Directive 9200.4-17, is
available in several electronic formats from
EPA's web site; the address is:
http:/ /www.epa.gov/swerustl/directiv /d9200417.htm.
The anticipated approval date for the ASTM stan-
dard of practice, Guide For Remediation Of Groundwater By
Natural Attenuation At Petroleum Release Sites, is March 10,
1998. As of press time, no designation has been.assigned
the standard. Please check the ASTM web page,
www.astm.org, to obtain up-to-date information. For
information about ASTM or the work of committee E-50
(for UST/LUST-related work), contact Susan Canning at
(610) 832-9714. •
Matt Small is with the Underground Storage Tank Program
Office, U.S. EPA Region 9, and is Co-chair of the
ASTM RNA Task Group. He may be contacted at
small.matthew@epamail.epa.gov.
Hal White is with the U.S. EPA Office of Underground Stor-
age Tanks in Washington, D.C. and is Co-chair of the OSWER
MNA Workgroup. He may be contacted at white.hal@epa-
mail.epa.gov. No official support or endorsement by the Envi-
ronmental Protection Agency or any other agency of the federal
or state government is intended or should be inferred. Mention
of trade names or commercial products does not constitute
endorsement or recommendation for use.
11
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LUSTLine Bulletin 28
A COMPARISON BETWEEN TtfE ERA MNA DIRECTiyE, AND; JHE,A^I!I1JNA jSJAHAiD.
EPA MNA Directive
OSWER Policy
ASTM RNA Standard
Industry-Consensus Standard
Applicability and Audience
RCRA, Superfund, and LIST program-regulated sites.
LIST program sites.
Definition of Natural Attenuation
All attenuation mechanisms, including those affecting
nonbiodegradable contaminants.
Mechanisms affecting biodegradable components
of petroleum products.'
Contaminants of Concern and
Affected Media
Petroleum hydrocarbons as well as organic solvents
and other hazardous chemicals, inorganics, metals,
radionuclides, and mixed-waste contaminants in
grqundwater and soil.
Petroleum hydrocarbons in groundwater.
Remedy Selection Criteria
MNA is not a "default" or "presumptive" remedy, it is
one of many potential remedies. Selection is site-
specific and all relevant program-dependent criteria
must be met. Requires site characterization, source
control, performance monitoring, and contingency
remedies (where appropriate).
In general, RNA should not be considered a pre-,
s'umptive remedy. Selection requires site characteri-
zation, assessment of potential risks, and evaluation
of potential to meet remedial goals.
Site Characterization
Adequate to demonstrate that MNA is an appropriate
remedial technology—generally more extensive than
active remedial technologies.
Same requirements as for any other remedial option.
Recommend collecting secondary lines of evidence
at new sites.
Evidence of Natural Attenuation
Primary (historical concentration data) and sec-
ondary (hydrogeologic and geochemical data) typi-
cally required. Tertiary (field or microcosm data)
required when primary and secondary data are inade-
quate or inconclusive.
Primary (historical concentration data), secondary
(geochemical data), and optional (modeling, assimila-
tive capacity estimates, and microbiological studies).
Secondary and optional data can be used to support
choosing RNA at sites with no historical data.
Groundwater Plume Status
MNA is more likely an appropriate remedial technol-
ogy at sites where plume is no longer increasing or is
shrinking.
RNA is appropriate for stable or shrinking plumes
and, in some cases, expanding plumes if risk reduc-
tion and performance goals are met.
Remediation Time Frame
Time required to reach remedial goals is site-specific
and should be "reasonable" when compared with
active remedial technologies.
Time frame must be considered as part of establish-
ing remedial goals. It is left up to regulatory agency.
Source Control
Evaluate all sites regardless of remediation technol-
ogy selected. Remove free product to the maximum
extent practicable. Source area removal and/or treat-
ment is preferred.
Integrate evaluation of need for source area control
measures into remedial decision-making at all sites
where RNA is under consideration. Degree of source
control or removal required is at the discretion of the
regulatory agency. Approval of RNA may require
source area removal or more aggressive remediation
based on potential risk.
Performance Monitoring
An essential component of any remedial option,
especially MNA. Monitoring program is based on
site-specific conditions and should continue as long
as contamination levels remain above specified
cleanup goals. Site closure is generally 1 to 3 years
after contamination levels have decreased sufficiently
to achieve, and remain at or below, cleanup goals.
Minimum of one upgradient point and two or more
monitoring points within the plume but outside free
product zone, and a downgradient monitoring point.
Frequency based on site-specific conditions; no
receptor impacts; remedial goals met or proven to
ultimately be met; plume stable or shrinking; and, if
needed, institutional controls in place and maintained.
Remediation Objectives
Defined as the overall objectives that remedial
actions are intended to accomplish—although not
the same as chemical-specific cleanup levels, these
may be included as part of the objectives. Cleanup
levels are site-specific and consider such factors as
risk and current and potential future uses of the
affected resource.
Determine remedial goals by applying risk-based cor-
rective action. Goals may take the form of concentra-
tion target levels or performance criteria, including
containment, and can be developed through predic-
tive modeling.
Contingency Remedies
Need should be evaluated for every site where MNA
is proposed, and implemented if concentration
decreases do not meet expectations.
Should be implemented if data indicate'that RNA will
not meet remedial goals, including containment.
No Further Action
Monitoring should continue as long as contamination
levels remain above required cleanup levels. Once
cleanup levels are met, additional monitoring is
needed to ensure that conditions persist.
No existing or potential receptor impacts. Remedial
goals are met, or it has been demonstrated that natural
attenuation will continue and ultimately meet remedial
goals. The plume is stable or shrinking. If needed, insti-
tutional controls are in place and maintained.
12
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LUSTLine Bulletin 28
Investigation and Remediation
To Methaiiol Preserve or Not to
Methanol Preserve? (That is the Question)
•o
by Blayne Hartman
ver the past few years, several states (e.g., Wisconsin, Massachu-
setts, Maine, New Mexico) have adopted regulations or policies
requiring that soil samples1 slated for volatile organic compound
(VOC) analysis be preserved in methanol immediately upon collection.
Other states are considering similar measures. Why is this?
We have known since the early 1990s that volatile compounds can be
lost quite readily from soil samples, even when the soils are kept chilled. A
number of articles written by independent researchers have demonstrated
that VOC losses from soils can reach 50 percent within 2 hours of collection
and can exceed 90 percent within 24 hours. However, when preserved in an
organic solvent, such losses were prevented. Fearing that regulatory deci-
sions were being made based on data that woefully misrepresented true
concentrations, the Wisconsin Department of Natural Resources adopted a
methanol preservation requirement in 1994. Other state agencies began to
follow Wisconsin's lead. But, alas, questions linger.
Preservation Protocol
At first glance, the preservation pro-
tocol appears simple enough: Upon
collecting an aliquot of the soil sam-
ple (typically 5 to 10 grams), immedi-
ately immerse it in vials containing
methanol (typically 5 to 10 mL). Seal
the vials and transfer them to the lab-
oratory for subsequent analysis. Col-
lectors may use vials containing
premeasured amounts of methanol
obtained from the laboratory prior to
the sampling effort, or alternatively,
they may purchase the methanol
directly and add it to the vials them-
selves. The result? Immediately pre-
served soil samples that bear values
more indicative of the true soil con-
centrations.
So What's the Worry?
Methanol has an extremely high
affinity for many organic com-
pounds. In fact, laboratories some-
times receive freshly purchased
methanol with contaminant levels
exceeding method detection limits.
Once opened, a bottle (or vial) of
methanol will adsorb organic com-
pounds rapidly; the "shelf life" is
very short if any organic compounds
are immediately present. Because
prices for laboratory-grade methanol
can exceed $30 per liter, it is difficult
to "toss away" a partially used bottle
of methanol once opened.
So now let's travel to the job
site. Our on-site environmental geol-
ogist is busy directing and supervis-
ing the sampling subcontractor (e.g.,
driller, excavator), logging samples,
screening samples with a hand-held
PID, washing sampling sleeves, and
communicating with the front office.
Where does this flurry of activity
normally take place? Typically on a
tail gate of a pick-up truck (or some
equivalent workbench), in close
proximity to the sampling truck.
Now lef s add methanol preser-
vation to the other tasks. If every-
thing is going fine, the methanol
preservation step should be rela-
tively painless. However, what hap-
pens when things don't go so fine?
The driller has problems. The wind
shifts and the "work area" is now
downwind of the diesel exhaust. The
job's running late and everyone is in
a hurry. It starts to rain. The office
calls. Now what happens to the vials
or bottle of methanol? Was it left
uncapped for a while? Do we use it
the next day if the job shuts down for
some reason? Two days later? Three
days? How does one know if the
methanol is still okay? What hap-
pens if the methanol-preserved sam-
ples are put in the same cooler as the
highly contaminated soils them-
selves? Will the samples cross-conta-
minate the methanol extracts?
The point is
that the potential
for false positives from
contaminated methanol
increases with methanol
preservation. If it occurs, the false
positives will most likely not be dis-
covered until after the job is demobi-
lized. In this situation, who pays for
the job to be redone? The tank fund?
The consultant? The lab? Or does the
job not get redone and the data "cor-
rected" before submission?
Are There Alternatives?
Yes. The best alternative is on-site
analysis. On-site analysis mitigates
the volatile loss problem and also
mitigates the potential for false posi-
tives because the real-time analysis
will reveal the existence of the conta-
minated methanol before it is too late
to correct the problem. Costs for on-
site analysis have dropped over the
past few years, and many reimburse-
ment funds now allow it.
If the budget or logistics do not
allow for the use of methanol, you
have the alternative of using water as
the preservation liquid. While this
may initially sound strange, it turns
out that MTBE, most aromatic com-
pounds (BTEX), and many chlori-
nated compounds prefer to be in
water over air by ratios exceeding 4
to 1. Thus, in a vial filled with 5
grams of soil, 5 mL of water, and 5 cc
of air, 80 percent of the analyte will
partition into the water. If the water
to air ratio in the vial is 2 to 1 (say, 10
mL to 5 cc), about 90 percent of the
analyte will partition in the water.
Why water over methanol?
Because inexpensive, uncontami-
nated water is readily obtainable at
every convenience store and its shelf
life is much longer than that of
methanol. If the job gets delayed for
a day or two or three, a fresh,
unopened bottle of drinking water
can be purchased for $1.
• continued on page 21
13
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LUSTLine Bulletin 28
Investigation and Remediation
The Downward Migration of Vapors
by Blayne Hartman
Tn the last issue o/LUSTLine,zue discussed potential risk to human health with respect to the upward migration of vapors
j into overlying structures. In that scenario, the health risk of concern was the inhalation of contaminant vapors from room
J~ air. Tills risk pathway has gained increasing attention over the past several years and has been addressed in a number of
published documents, including the 1995 ASTM Risk-Based Corrective Action (RBCA) document.
In contrast to the upward vapor risk, potential risk to groundwater associated with the downward migration of vapors
has been relatively ignored. The principal reason for this is that it is generally assumed that contaminated soil vapor is the
result of contamination in the soil. Therefore, there is the perception that the real risk to groundwater is not the soil vapor, but
the contaminant in the soil that makes its way to the groundwater.
So why worry about risk associated with downward vapor migration? Because, over the past few years, more and more
sites have been discovered that have high contaminant concentrations in the soil vapor but no corresponding soil contamina-
tion. In this article, I'll explore this phenomenon. Is it a problem? If it is, then when should we start to worry?
Vapor Clouds
How can a site have contaminated
soil vapor with no corresponding
soil contamination? One explanation
is that the contamination entered the
vadose zone as a vapor. Many com-
pounds in fuels and many chlori-
nated solvents have relatively high
vapor pressures and vapor densities
three to six times greater than those
of air. Because of these physiochemi-
cal properties, vapors may emanate
from containers holding gaseous or
liquid products that are used or
stored in an indoor confined space or
from pipe joints and then sink to the
floor. If air flow is restricted, such as
in a closed room, the dense vapors
can penetrate the concrete floor and
enter the upper vadose zone.
Such bulk-dense vapor move-
ment will continue to drive the vapor
downward through the vadose zone
until it is diluted to low enough con-
centrations (<1 percent) that density
is no longer an important factor in
the vapor transport process. "Vapor
clouds" reaching tens of feet into the
uppermost vadose zone have been
documented and attributed, at least
in part, to density-driven flow. Busi-
ness and commercial operations that
are most susceptible to this situation
include perchloroethylene (PCE)
washing units at dry cleaners, vapor
degreasers at machine shops, and
spray booths at inking or painting
facilities where chlorinated solvent-
based inks or paints are used. As far
as USTs are concerned, underground
vent pipes are typically filled with
high concentrations of MTBE and
Depth (X) /
Water Table
Soil Gas
Concentration
(Csg)
^Equilibrium Groundwater
1 Concentration (Ceg)
Contact Distance (d)
Groundwater (Cw)
gasoline vapors that can conceivably
migrate through pipe joints and cre-
ate vapor clouds.
As vapor clouds are discovered
in the vadose zone at more and more
sites, we must try to determine
whether they are a potential risk to
groundwater. If they are, at what soil
vapor concentrations should we start
to worry? I'll start with a quick
review of the basic processes by
which vapors move through the
vadose zone. (Refer to LUSTLine Bul-
letin #27 for a more complete discus-
sion.) Then I'll discuss, compute, and
summarize in a table the potential
risk that results from downward
vapor migration. I'll conclude with a
recommended protocol for collecting
soil vapor data for assessing the
downward vapor risk. Like my article
on the upward migration of vapors,
this one will also be somewhat techni-
cal; however, I have attempted to
keep the subject understandable and
have refrained from including so
many "daunting" equations.
How Do Contaminants Move
in the Vapor Phase?
There are primarily two types of
physical processes by which contam-
inants are transported in the vapor
phase: advection and gaseous diffu-
sion. The process of advection refers
to the bulk movement of the vapor
itself (e.g., the movement of vapor by
wind). In advective transport, any
contaminants in the vapor are car-
ried along with the moving vapor.
Advective transport processes can be
14
-------
LUSTLim Bulletin 28
an important factor in the movement
of soil vapor. This phenomenon is
especially true where vapors are
near the ground surface, where
atmospheric pressure variations
come into play, or near buildings,
which can create pressure gradients
because of differential heating or
density-driven flow.
The second type of transport
process, gaseous diffusion, refers to
the motion of the contaminants by
molecular processes through a non-
moving vapor column. Gas diffusion
is the primary transport mechanism
for contaminants in the vapor phase
through the vadose zone down to
groundwater. Contaminant trans-
port by gaseous diffusion is
described by Pick's first law as:
Flux —
dX
Where:
• Flux is the rate of movement of
a compound per unit area.
• De is the effective diffusion
coefficient in the vadose zone.
• dC is the contaminant con-
centration gradient in the soil
vapor.
• dX is the depth interval in the
vadose zone.
Similar to momentum transfer (e.g.,
water running downhill) and heat
transfer (i.e., movement from hot to
cold), contaminant transfer by
gaseous diffusion moves from areas
of high concentration to areas of low
concentration. The flux will always
be down the concentration gradient,
regardless of the orientation of the
concentration gradient with respect
to depth below the surface.
How Fast Do Contaminant
Vapors Move?
An approximation of the mean dis-
tance that contaminant vapors can
move by gaseous diffusion can be
made as:
Distance = (2 x De x t)v*
Where:
• De is the effective diffusivity.
• t is time.
Through the Vadose Zone
The effective diffusion coefficient
for contaminant vapor transport
through the vadose zone is the
gaseous diffusion coefficient cor-
rected for soil porosity. For many
vapors, the gaseous diffusion coeffi-
cient is approximately 0.1 cm2/s.
The effect of soil porosity varies
depending on the type of soil. Sev-
eral equations are available to calcu-
late the effect of air-filled and total
porosity on the diffusivity. A conser-
vative approximation is that the
porosity reduces the gaseous diffu-
sivity by a factor of 10. Thus, for
vapors, De can be approximated as
0.01 cm2/s.
The mean distance that conta-
minant vapors can move through the
vadose zone in a year, assuming no
adsorption, can be estimated as:
Distance = (2 x 0.01 cm2/s x
31,536,000 s)1'*
~ 800 cm =-25 feet.
This calculation shows that
contaminant vapors can move long
distances through the vadose zone in
a short period of time. Within a few
years, vapor contamination can
move laterally underneath a neigh-
boring room or building, or down-
ward to the groundwater surface.
Into or Out of Groundwater
In contrast to movement through the
vadose zone, the movement of conta-
minant vapors into or out of ground-
.water is controlled by the rate at
which vapors partition into and
move through the liquid. Because
groundwater movement is so slow,
the water interface remains relatively
undisturbed (laminar flow), and ver-
tical mixing of the water is minimal.
The primary exchange process is
again molecular diffusion, but in this
case the exchange rate is controlled
by liquid diffusion, not gaseous dif-
fusion. A general value for the liquid
diffusion coefficient for compounds
is approximately 0.00001 cm2/s.
Using the same factor of 10 reduction
to account for soil porosity, De for
most liquids can be approximated as
0.000001 cm2/s.
The mean distance that conta-
minants can move into and through
the groundwater in a year, assuming
no absorption, can be estimated as:
Distance = (2*0.000001 cm2/s
x 31,536,000 s)1/2
~8 cm= ~3 inches
These calculations sKbw that
although contaminant vapors can
move through the vadose zone rela-
tively quickly, they partition into
and move through groundwater
extremely slowly. The reverse situa-
tion is also true; the partitioning of
contaminants out of groundwater
into the soil vapor is also extremely
slow and very unlikely to reach the
equilibrium values predicted by
Henry's law constants. The reason
equilibrium is not reached is because
the mixing processes between the
soil vapor and the groundwater are
extremely slow (i.e., there are no
blenders or mixers in the vadose
zone mixing things up).
Can the Downward
Transport of Vapors
Contaminate Groundwater?
The calculations summarized in the
preceding section indicate that
although contaminant vapors can
move quickly down to groundwater,
they .do not partition into the ground-
water very quickly. Using a modifica-
tion of Pick's first law, the transfer of
a contaminant from the soil vapor
into the groundwater can be esti-
mated. The flux is calculated as:
Flux = KL(Ce -Cw)
Where:
KL is the gas exchange coeffi-
cient (length/time).
C is the equilibrium water
"eq
concentration at the interface.
• Cw is the background ground-
water concentration.
C represents the groundwater
concentration in equilibrium with
the overlying soil vapor at the inter-
face between the soil gas and
groundwater. It is easily calculated
from the measured soil gas concen-
tration as:
Where:
• H is the dimensionless Henry's
law constant.
• C is the soil vapor concentra-
tion.
The gas exchange coefficient has
units of velocity and essentially rep-
resents the distance that contami-
nants move vertically through the
• continued on page 16
15
-------
LUSTLine Bulletin 28
• Downward Migration
from page 15
groundwater per unit time. This
exchange coefficient is primarily
dependent upon two transfer
processes: dispersion caused by
advective mixing and molecular dif-
fusion at the interface. A full discus-
sion of the relative importance of
these processes is beyond the scope
of this article; however, for ground-
water velocities less than 100 ft/yr
and soil grain sizes less than 0.5 mm,
diffusional transport dominates over
dispersion and KL can be approxi-
mated as:
KL-l.lxpexd/v)'4
Where:
• d is the horizontal distance
(downgradient) over which the
soil vapor plume and ground-
water are in contact.
• v is the horizontal groundwater
flow velocity.
Using this equation to estimate
the gas exchange coefficient, esti-
mates of the expected contaminant
concentration in the groundwater
that results from contamination in
the overlying soil vapor can be calcu-
lated. The computed groundwater
values are dependent on the depth
into the groundwater that the conta-
mination is mixed. The assumption
used in these calculations is that the
typical well-purging process mixes
(homogenizes) the contamination in
the groundwater uniformly over the
entire well screen interval. Table 1
summarizes expected groundwater
concentrations (Cw) for various equi-
librium concentrations (C ).
In order to use Table 1, you
must convert equilibrium ground-
water concentrations (Ceq) into the
corresponding soil vapor concentra-
tions. Remember that the corre-
sponding soil vapor values will vary
for different compounds because
Henry's law constants are com-
pound-specific. Table 2 summarizes
the soil vapor concentrations (Csg)
for various equilibrium concentra-
tions (Ceg) for four common com-
pounds (at 20°C).
Table 1 shows that for equilib-
rium concentrations up to 500 ;*g/L,
the resulting groundwater concen-
tration after 5 years will be low if li-
quid molecular diffusion is the only
Table 1
Expected contaminant concentration in groundwater for various
equilibrium concentrations (Ceq) at the groundwater interface.
Calculations assume equilibrium partitioning at the soil vapor /ground-
water interface, transfer by molecular diffusion only (De = 10 cm2/ s),
and uniform mixing of the contaminant into the groundwater over a well
screen interval of 5 meters.
Ceq
(ug/U
10
20
30
40
50
100
500
1000
Flux
(ug/yr-cm2)
0.08
0.16
0.24
0.32
0.40
0.80
4
8
1 yr GW Cone
(HO/L)
0.006
0.01
0.02
0.03
0.03
0.06
0.3
0.6
SyrGW
(ug/L)
0.28
0.55
0.83
1.1
1.4
2.8
14
28
Table 2
Soil gas concentrations (Csg) for four common compounds for
various equilibrium groundwater concentrations (Ceq) at the
groundwater interface (values at 20°C).
Ceq
(ng/L)
10
20
30
40
50
100
500
1000
MTBE
Csg (ug/L)
0.1
0.2
0.3
0.4
0.5
1
5
10
Benzene
Csg (ug/L)
2
4
6
8
10
20
100
200
PCE
csfl (ug/L)
6
12
18
24
30
60
300
600
Vinyl Cl
Csg (ug/L)
10
20
30
40
50
100
500
1000
16
-------
LUSTLine Bulletin 28
exchange process. Table 2 shows that
C values of 500 ug/L correspond to
soil vapor concentrations exceeding
100 ug/L for most compounds. In
most situations, contaminant vapor
concentrations at the groundwater
surface are far below 100 ^g/L, and
the contact time of the vapor contam-
ination with groundwater is less
than 5 years (the time it takes the
groundwater to move across the
site).
Thus, in areas with low
groundwater flow velocities, conta-
mination of the groundwater by
downward vapor transport is not
likely to be significant. In areas with
higher groundwater flow velocities
(>100 ft/yr), large variations in the
water table, coarse soil, or high
recharge, the gas exchange rate may
be higher because of dispersive mix-
ing. Groundwater contamination by
vapor transport could be significant.
Does the conclusion that down-
ward vapor transport into ground-
water is a slow process make
intuitive sense? The concept can be
illustrated if you think of what is
happening with air bubbles in a fish
tank. If the air bubbler is turned off,
the fish will go to the surface to gulp
air; without the bubbles, they'll even-
tually die. Air contains nearly 21 per-
cent oxygen, so there is plenty of
oxygen sitting on the surface of the
fish tank water. However, despite
the large supply of oxygen at the sur-
face, the transport mechanism into
the water (liquid diffusion) is too
slow across the laminar interface to
supply enough oxygen to the water
for the fish to live. So, the air must be
bubbled through the water to
increase the oxygen transfer process
(by creating turbulent mixing).
Protocol for Determining Risk
Caused by the Downward
Migration of Vapors
With Table 1 in hand, we can make
reasonable judgments on whether
measured soil vapor concentrations
are likely to be a threat to groundwa-
ter. In order to use Table 1, we need to
collect soil vapor data using the active
soil gas technique and collecting data
from as close to the groundwater
interface as possible. (See the last
issue of LUSTLine for a review of the
different sampling methods.) In some
situations (e.g., where the source of
the soil vapor contamination is
unknown or the depth to groundwa-
ter is uncertain), vertical profiles of
the soil vapor may prove useful for
determining the source of the contam-
ination and the values at depth.
Based on the discussion pre-
sented in this article, I recommend
the following procedure for collect-
ing soil vapor data that will be used
to determine risk to groundwater as
a result of downward vapor flux:
1. Collect active soil vapor data near
the water table at the location of
highest contaminant concentra-
tion. If the location of highest con-
taminant concentration is
unknown, collect soil vapor data
at 5 feet below ground surface
(bgs) across the site to identify the
location of highest concentration.
2. Calculate C from the measured
soil vapor values using the
Henry's law constant for the cont-
aminant of concern (or use Table
2). Use Table 1 to estimate the
impact to groundwater. If Table 1
indicates that downward vapor
poses no threat to groundwater,
then this risk pathway need not be
considered further, assuming the
source of the soil vapor contami-
nation is mitigated.
3. If Table 1 indicates that down-
ward vapor may pose a threat to
groundwater, then collect addi-
tional soil vapor samples near the
water table across the entire soil
vapor plume.
4. Calculate an average Ceq for the
entire plume. Use Table 1 to esti-
mate the impact to groundwater. If
Table 1 indicates that downward
vapor poses no threat to ground-
water, then this risk pathway need
not be considered further, assum-
ing the source of the soil vapor
contamination is mitigated.
5. If Table 1 still indicates that down-
ward vapor may pose a threat to
groundwater, then both the soil
vapor contamination and the cont-
amination source likely need to be
mitigated. •
Blayne Hartman, Ph.D., is Vice Presi-
dent and Technical Director of TEG,
Inc., in Solana Beach, California, and
is a frequent contributor to LUSTLine
on remediation issues He may be
reached at bh@tegenv.com.
Still Searching
for Integrity
February 10, 1998 - It's crunch
time for tank owners and opera-
tors who are looking to upgrade
their bare steel tanks without
putting a person inside the tanks
to inspect them. According to
EPA's Office of Underground
Storage Tanks (OUST), no ven-
dors currently meet its guidance
for "alternative" (non-human-
entry) integrity assessment meth-
ods issued in July 1997. The
guidance recommends that after
March 22,1998, states allow alter-
native integrity assessments on
bare steel tanks only if the proce-
dure meets a current national
standard or if it has been evalu-
ated by a third party to meet cer-
tain criteria.
According to the American
Society of Testing Materials
(ASTM), a standard code of prac-
tice will not be ready by the
March 22 recommended dead-
line. However, an ASTM task
group in which EPA is participat-
ing continues work on a draft
standard.
To OUST's knowledge, no
vendor's procedure has com-
pleted a third-party evaluation in
accordance with EPA recommen-
dations. The "FURY" robotic
ultrasound procedure has had
some evaluation, but no final
evaluation has been completed.
Some states recently received
documentation, dated January
19, 1998, from Corrpro Compa-
nies Inc. and Warren Rogers
Associates Inc. (WRA), asserting
that their procedure meets the
criteria. EPA says that the docu-
mentation does not fulfill its cri-
teria for integrity assessment.
Corrpro and WRA plan to pro-
vide more documentation.
Meanwhile, OUST has been
contacted by some vendors who
have indicated that third-party
evaluations for their procedures
are under way and, therefore,
expects that some evaluations
will be completed soon. EPA will
distribute lists of completed eval-
uations periodically. •
17
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LUSTUnc Bulletin 28
MTBE & Underground Storage Tank Systems
A Question of Compatibility
by James M. Davidson
Methyl tertiary butyl ether
(MTBE) was first used
commercially in the
United States as a gasoline additive
in 1979. Its use increased gradually
through the 1980s as an octane
enhancer (typically 1-8% by vol-
ume). By the 1990s, higher levels of
MTBE (11 - 15%) were added to
gasoline in order to increase oxygen
levels, and thereby reduce air pollu-
tion. Now, about half of all gasoline
sold in the United States contains
MTBE. (For an in-depth introduc-
tion to MTBE, see "MTBE...lf Ye
Seek It, Ye May Well Find lt...And
Then What?" in LUSTLine Bul-
letin #24.)
Common sense tells us that if an
underground storage tank (UST)
has an accidental release of gasoline,
and the gasoline contains MTBE,
then MTBE will escape into the
environment along with the other
gasoline components. However, with
the recent discovery of subsurface
MTBE contamination at many UST
facilities, concern has arisen whether
MTBE can preferentially leak from
UST systems, or whether the MTBE
itself can cause leakage from UST
systems. Some people are fearfully
wondering: Is there something about
MTBE that causes releases from
USTs?
In this article I revieiu the avail-
able knowledge regarding the com-
patibility of MTBE with UST
systems, as extracted from published
studies and as collected from discus-
sions with numerous UST experts.
As I'll explain, it does not appear
that there are any obvious compati-
bility problems between USTs and
the gasoline additive MTBE. On
many of the specific compatibility
issues, significant supporting scien-
tific data exist. However, for a few
topics the available information is
limited or contradictory, and so
more research is needed.
COMPATIBILITY = The abil-
ity of two or more substances
to maintain their respective
physical and chemical properties when
in contact with one another. For UST systems, compatibility
with the substance stored must be for the design life of the
tank and under conditions likely to be encountered in the UST.
UST Systems
Modern USTs are most often made
of cathodically protected steel, fiber-
glass-reinforced plastic (commonly
called fiberglass), or composite mate-
rials (such as steel with fiberglass
coatings). Product piping used in
modern underground storage tank
systems is typically made of fiber-
glass or thermoplastic lined with
nylon (associated with flexible pip-
ing). Bare steel product piping is, of
course, more typical in older UST
systems.
When considering the compati-
bility of gasoline, or a gasoline addi-
tive, with UST system components,
one should take into account:
• Compatibility with metal tanks
and piping;
• Compatibility with fiberglass
tanks and piping;
• Permeability of liquid and
vapors through the UST system
components;
• Compatibility with flexible pip-
ing; and
• Compatibility with seals and
gaskets.
Compatibility with Metal
Tanks and Piping
Like all other oxygenating additives,
MTBE adds oxygen to gasoline, so
we need to consider whether oxygen
enhances corrosion of metal tanks
and piping systems. In 1988, Sun
Refining and Marketing Company
(an early major manufacturer of
MTBE) tested this possibility by
immersing metal samples (also
called "coupons") in seven gasoline
blends (some with MTBE levels of up
to 15% by volume, some with no
MTBE) for 6 to 7 months. Nine differ-
ent metals commonly used in auto-
motive fuel systems and gasoline
distribution systems were tested.
The metal coupons showed small
weight changes in all the fuels.
Weight loss (i.e., corrosion) of the
10/20 steel coupons over 6 months
of immersion increased from a 2.95
percent weight loss to a 10.75 percent
weight loss when MTBE was added
to the base gasoline. While this dif-
ference is noteworthy, the
researchers concluded that "the
small amount of weight loss indi-
cates no potential problems."
In 1989, two other researchers
(Lang and Palmer) reported on a
compatibility study that used stan-
dard reference gasolines combined
with four possible gasoline addi-
tives: methanol, ethanol, tertiary
butyl alcohol (TEA), and MTBE.
Through a variety of immersion
tests, they tested gasoline mixtures
of all these additives for tendency to
corrode metals commonly used in
automobiles, including brass, alu-
minum, zinc, and mild steel. They
found that MTBE was the least
aggressive of the additives tested.
18
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LUSTLine Bulletin 28
I found no other pertinent stud-
ies pertaining to MTBE and metal
tanks and piping.
Compatibility with Fiberglass
Tanks and Piping
Many modern USTs and product
pipes (including many double-
walled systems) are made from fiber-
glass. Similar to the compatibility
testing on metals, several series of
immersion tests have been con-
ducted on fiberglass. In 1988, Sun
conducted fiberglass compatibility
testing with six test fuels (two base
gasolines with no MTBE and four
fuel blends with MTBE at 7.5% -
15%). Testing was conducted by
immersing a coupon of fiberglass
tank material (Xerxes) in the six test
fuels for 7 months at 68 to 70°F.
Essentially, no volume changes were
measured for any of the fiberglass
tank coupons after 6 months of
immersion in the test gasolines.
A subsequent publication pro-
vides additional results from these
same 7-month-long immersion tests
(Douthit et al., 1988). The paper
reports that the fiberglass tank sam-
ple had volumetric shrinkage of 0.35
percent when immersed in a base
gasoline (no MTBE), a volumetric
shrinkage of 0.33 percent when in the
base gasoline with. 11 percent MTBE,
and a volumetric shrinkage of 0.24
percent when immersed in the base
gasoline with 15 percent MTBE. In
other words, the MTBE-blended
gasolines had slightly less volumet-
ric impact on the fiberglass than did
the base gasoline.
Also in 1988, Sun conducted
similar immersion testing on Ciba-
Geigy fiberglass piping. After 7
months, the volumetric change for
piping sections in MTBE-blended
gasolines ranged from +2.26 percent
swelling to -1.32 percent shrinkage.
The Sun researchers reported that
these volumetric changes were
smaller than those seen with most
other components and materials pre-
viously tested. Additional reporting
on these same tests indicated that the
fiberglass pipe samples had volu-
metric "swelling" of 0.33 when
immersed in a base gasoline (no
MTBE), a volumetric shrinkage of
1.09 percent when in the base gaso-
line with 11 percent MTBE, and a
volumetric shrinkage of 0.43 percent
when immersed in the base gasoline
with 15 percent MTBE (Douthit et al.,
1988); These data indicate that the
MTBE-blended gasolines caused
slightly greater volumetric change in
the fiberglass piping samples than
did the base gasoline.
Even more "real world" are the
recently released results of long-term
compatibility testing by one of the
fiberglass manufacturers (Fluid Con-
tainment). Although a full report
was not available for review at press
time, in a summary of its findings,
Fluid Containment describes a series
of long-term immersion tests.
Researchers placed a series of
nine fiberglass samples in gasoline
with 20 percent MTBE for up to 94
months. They report that throughout
this nearly 8-year test period, the
hardness and strength of the fiber-
glass samples did not vary by more
than 2 percent from their original
values.
These ranges in values are simi-
lar to those seen with fiberglass sam-
ples exposed to gasoline with no
MTBE for equal durations. Fluid
Containment concluded that "the
MTBE fuel blend acted no differently
than straight gasoline and had-essen-
tially no effect on the tank sample
after almost 8 years" (Fluid Contain-
ment, 1997). The company also
reported that it had not experienced
a single tank failure from internal
corrosion, with over 250,000 fiber-
glass tanks sold. (This number
includes tanks manufactured under
its present name and its previous
name of Owens-Corning Fiberglass,
Tank Division).
You may wonder: If fiberglass
is compatible with MTBE, what
about the glues used to bond fiber-
glass systems together? In neither a
thorough literature search nor dis-
cussions with knowledgeable UST
experts could I establish any cases
where MTBE was suspected of hav-
ing dissolved the glues used with
fiberglass systems. The only related
information I found was in two early
American Petroleum Institute publi-
cations (API, 1985 & 1986), where it
was noted that some alcohol-based
pipe thread dopes were not recom-
mended for use with methanol or
ethanol-blended gasoline if the pipe
dope had been recently applied.
In summary, several short-term
(6 to 7 months) immersion tests
showed no difference to very little
difference in how MTBE-enhanced
gasoline affected fiberglass samples,
as compared with gasolines without
MTBE. Long-term (nearly 8 years)
immersion tests by Fluid Contain-
ment showed similar results.
Permeability Through
Fiberglass
I found some information regarding
the possibility that MTBE permeates
directly through the walls of fiber-
glass tanks and pipes. One study
(Smith Fiberglass Products Inc.,
1996) investigated liquid gasoline
permeability through fiberglass pipe
by using standard permeability test-
ing methods. This study showed,
essentially, that no liquid gasoline
loss occurred through the fiberglass
piping after 31 days while using 90
percent gasoline and 10 percent
ethanol (not MTBE). This test
demonstrates the extremely low per-
meability of fiberglass piping to liq-
uid gasoline components. MTBE-
blended gasoline was not tested.
Sun tested the evaporative
losses of six gasoline blends from
several types of vehicle fuel-line and
gasoline-dispenser hoses. The 6-
month evaporative-loss tests showed
that "there were no large differences
between the samples containing base
fuel and samples with base fuels and
15 percent MTBE" (Sun, 1988).
In a 1996 letter to Fluid Con-
tainment, Bruce Curry of Alpha/
Owens-Corning discusses the poly-
mer being used in the manufacture
of the company's fiberglass tanks.
He reported that larger molecules in
liquids have a more difficult time
permeating fiberglass laminates
than do smaller molecules. Since the
• continued on page 20
""19
-------
• Compatibility from page 19
molecular size of MTBE (molecular
weight *= 88) is fairly large, it would
not be likely to swell fiberglass or to
be readily permeable through fiber-
glass. In contrast, smaller molecular
compounds like methanol (molecu-
lar weight - 32) would be more per-
meable. This same viewpoint was
expressed in a 1997 paper by Sully
Curran, Executive Director of the
Fiberglass Tank and Pipe Institute.
Alpha/Owens-Corning (1996) also
states that MTBE would not be
prone to affecting fiberglass lami-
nates because of its relative chemical
inertness. In summary, the opinions
of the fiberglass manufacturers and
experts are in agreement that
MTBE's molecular size should deter
its permeation through fiberglass.
Fiberglass Manufacturers'
Warranties
In a 1995 letter to its customers,
Owens-Corning/Fluid Containment
said that it had extensively tested
fuels containing up to 20 percent
MTBE and that there was very little
effect on the fiberglass laminate. As a
result, Fluid Containment has war-
rantied its tanks against internal cor-
rosion for 30 years for the storage of
up to 20 percent MTBE for any of its
tanks manufactured since 1964.
Another major manufacturer,
Xerxes, first listed MTBE-blended
gasolines (up to 20% MTBE) on its
April 2, 1988, warranty, where it
warrantied its fiberglass tanks for 30
years. Prior to April 2,1988, MTBE
was not mentioned in the Xerxes
warranty, although other, more
aggressive additives (i.e., alcohols)
had been previously addressed and
covered by warranty.
Compatibility with
Flexible Piping
While many product piping systems
are made from fiberglass-reinforced
plastic, the use of flexible piping sys-
tems (made from thermoplastics or
polyethylene) has increased greatly
in recent years. In a 1997 data compi-
lation conducted for USEPA, ICF Inc.
found that seven of the eight manu-
facturers of flexible piping had tested
and approved their piping systems
for primary pipe compatibility with
MTBE-blended gasolines. Five of the
eight manufacturers had tested and
approved their flexible-piping sys-
tems for secondary pipe compatibil-
ity with MTBE-blended gasolines.
One manufacturer did not report
whether MTBE had been tested yet.
While this summary is promising, no
details were available regarding the
testing conducted on MTBE's com-
patibility with flexible piping. No
information was found regarding
studies of MTBE permeation through
flexible piping, and so no conclusion
can be made. This topic may warrant
additional research.
between USTs and the gasoline
B^jja£»HmBPtafl^#8^^«wi»pt
'addHiygMTB^L^
|p7/cs the available information is
:Jlniile£ro£^^radicjojy,and_so
i
more research is needed.
Compatibility with Seal and
Gasket Materials
Several studies have shown that
"pure" (or "neat") MTBE can
adversely affect some elastomeric
materials used in seals and gaskets.
Seal and gasket deterioration from
exposure to pure oxygenates usually
comes in the form of swelling and
softening (API, 1990; Alexander et
al., 1994). However, these data are
Not directly applicable to releases
from USTs as USTs are Not used to
store neat MTBE.
When considering MTBE as a
gasoline-blending component, a 1994
study used MTBE at 20 percent by
volume (which is higher than current
commercial grades) for immersion
tests on six seal materials. After 168
hours of immersion, five of the seal
types (including two types of Viton)
had no swelling and one Viton for-
mulation had minor swelling (about
12%). The researchers concluded that
MTBE did "not significantly swell
any of the elastomeric seals tested,"
and that all six seals were deemed
appropriate for use when MTBE con-
centrations were less than 20 percent
of the gasoline (Alexander et al.,
1994). This immersion study pro-
vides much useful information, but
some followup work may be advis-
able because of the relatively short
duration of the tests (1 week).
Similarly, Lang and Palmer
(1989) conducted immersion tests to
determine fuel additive compatibil-
ity with five common commercial
mixes of rubbers (elastomers) used in
vehicle fuel systems. Using standard
reference gasolines containing either
methanol,'ethanol, TEA or MTBE,
they determined that MTBE was the
least aggressive additive toward rub-
bers.
A variety of plastic and elas-
tomeric parts commonly used in
automobiles and gasoline distribu-
tion systems were tested in 7-month-
long immersion tests (Sun, 1988).
Fifteen materials and automotive
components were immersed in six
test fuels at 68 to 70°F. Results
showed that some materials had
about the same swell in 15 percent
MTBE gasoline as in non-MTBE
gasoline, while other materials
swelled less. Only Viton seal formu-
lations had more swell (up to 7%)
with MTBE present, though the
degree of swelling was not consid-
ered significant by the authors (Sun,
1988).
Since 1985, the General Valve
Company (as reported by Smith in
1995) has worked closely with
DuPont to conduct Viton compatibil-
ity testing. General Valve concluded
that up to 25 percent MTBE in gaso-
line will not diminish the life of the
Viton Type A (66% fluorine) seals
commonly used in petroleum stor-
age and transport facilities. Simi-
larly, a comprehensive study by
Aloisio (1994) investigated how
gasoline can impact various elas-
tomers, depending upon such vari-
ables as temperature, fluorine
content, and MTBE content. He
reported that because blending
MTBE into gasoline reduces the
fuel's polarity, the fluorocarbon elas-
tomers (like Viton) can be used with
MTBE-blended fuels, as long as the
concentration of MTBE in the gaso-
line does not exceed 25 to 30 percent.
This highly technical paper would be
best interpreted by a materials spe-
cialist.
Another comprehensive study
of the MTBE impacts on seal materi-
als was conducted by Hotaling
(1995). Seal material samples were
exposed for 6 months to test fuels of
20
-------
LUSTLine Bulletin 28
100 pefc-ertf MTBE, 95 percent gaso-
line with 5 percent MTBE, and 100
percent MTBE vapors. The seal mate-
rial parameters tested were volumet-
ric swell, tensile strength, and
elongation. Similar to other studies,
Hotaling found the 100 percent
MTBE liquid impacted seal materials
much more than the 5 percent MTBE
gasoline blend. In contrast to other
researchers, Hotaling reports that
even the 5 percent MTBE-blended
gasoline created serious degradation
of some seals.
MTBE Vapors
Vapor-phase MTBE is of interest
because MTBE's high vapor pressure
(roughly three times that of benzene)
can, theoretically, cause the vapors in
an UST system to be more enriched
with MTBE than the liquid gasoline
from which the vapors originally
evaporated. (No literature was found
that documented the composition of
recovered vapors from MTBE-
enhanced gasoline.) As such, gaso-
line vapors, or liquid gasoline
condensates that form from those
vapors, will likely contain relatively
high percentages of MTBE. MTBE-
enriched vapors could occur inside
the headspace of USTs and also
inside the vapor recovery system.
Liquid-phase MTBE-enriched con-
densate could form in small volumes
inside the vapor recovery system.
Hotaling (1995) reports that
many seal materials tested in 100
percent MTBE vapors experienced
"significant adverse changes in the
properties measured." Some of the
seals that reacted very little with 5
percent MTBE gasoline were
severely impacted by 100 percent
MTBE vapors. The opposite is also
true—some of the seals that reacted
very strongly with 5 percent MTBE
gasoline were not impacted by 100
percent MTBE vapors. These com-
plex responses are not fully under-
stood.
While MTBE may constitute a
significant portion of the vapors in
an UST headspace and vapor recov-
ery system, it certainly won't consti-
tute 100 percent MTBE. Therefore,
Hotaling's study may not be directly
applicable. However, the limited
data reviewed here do suggest that
vapor-phase compatibility with, and
vapor-phase permeability through,
the tank, piping, and seal materials is
a topic that requires further study.
In Summary...
• • Of the common gasoline addi-
tives, MTBE was found to be
the least aggressive to steel and
other metals. One study indi-
cated that adding MTBE to
gasoline increased the weight
loss from some steel coupons.
• All studies reviewed here indi-
cated that MTBE-blended gaso-
line is compatible with
underground storage tanks and
piping made from fiberglass.
• Permeation of liquid-phase
MTBE directly through fiber-
glass materials seems unlikely,
but only limited test data were
available.
• Regarding flexible piping, most
manufacturers state that their
products are compatible with
MTBE-blended gasolines; how-
ever, information is limited.
• Of the numerous tests con-
ducted on seal and gasket
materials, almost all indicated
they were compatible with the
range of MTBE concentrations
used in gasoline (i.e., up to 15%
MTBE by volume). However,
because of conflicting findings
from one report and the numer-
ous seal/gasket materials in
use, additional investigation
would be beneficial.
• Because of MTBE's high vapor
pressure, some vapors and con-
densates enriched with MTBE
may exist in UST systems.
Therefore, how vapor-tight,
how compatible, and how per-
meable the UST system compo-
nents are to MTBE-enriched
vapors and/or MTBE-enriched
condensates appear to need
further investigation.
After reviewing the available litera-
ture and speaking with numerous
UST experts, I have concluded that
currently there are no obvious com-
patibility problems between USTs
and MTBE used as a gasoline addi-
tive. Supporting scientific data dem-
onstrate that MTBE-blended gasoline
is compatible with UST tanks and
pipes made from either fiberglass or
metal, as well as many common
elastometric seals. However, the
available information regarding per-
meability and vapor-phase compati-
bility are limited. More research on
these topics and other compatibility
issues would be beneficial. •
See page 30 for references cited in this
article.
James Davidson is a hydrogeologist
and the President of Alpine Envi-
ronmental, Inc. (Fort Collins,
Colorado). He has extensive experi-
ence with mitigating petroleum
releases and has been conducting
applied research on MTBE environ-
mental impacts for several years.
He may be reached at
JimDavidson2@Compuserve.com.
• To Methanol Preserve or Not?
from page 13
Thus...
If you choose to
use methanol
VOC preserva-
tion, be sure to
take appro-
priate steps
(e.g., addi-
tional trip "*.., ^/
blanks) to ensure
that the methanol doesn't
become contaminated. While
methanol preservation certainly is
a proven way to maximize VOC
concentrations from soil, the reali-
ties of life in the field introduce
potential complications that may
favor other alternatives. On-site
analysis is by far the best alterna-
tive. Water preservation, although
not as quantitatively accurate as
methanol, does provide certain
advantages depending on the com-
pounds of interest. If water preser-
vation is performed, the preserved
samples should be kept chilled
(4°C) and, preferably, poisoned
with a bactericide to eliminate
biodegradation prior to analysis. •
21
-------
LUSTLine Bulletin 28
Leak Detection;;'
Are Leak Detection Methods Effective in
Finding Leaks in UST Systems?
California Survey Uncovers Some Cold, Hard Facts
Shahla Dargahi Farahnak
The increased use of oxygenates
as fuel additives combined
with recent concern over envi-
ronmental and health effects of some
of these additives, such as MTBE, has
drawn attention in California to the
reliability of leak detection systems.
For this reason, staff at the California
State Water Resources Control Board
conducted a survey to determine the
effectiveness of leak detection meth-
ods in finding UST system leaks. A
total of 345 leak cases (reported
between October 1995 and May
1996) were included in the survey.
How Are UST Releases
Detected?
One important question we sought
to answer in our survey was: How
are UST releases, in fact, detected?
Information on the leak discovery
method was available in 313 cases—
some was included in the original
statewide database, and some was
provided by local permitting agen-
cies. Analysis of these data indicates
that tank closure is the dominant
method for discovering leaking USTs
(84%). In most cases, therefore, we
do not know about leaks until the
UST system is removed.
What About Leak Detection?
Because of what the survey data
revealed, we became concerned
about the consistent use of leak
detection methods. At many of the
leaking sites, leak detection was not
used or was not performed regu-
larly. For 281 cases for which we
received a response, an estimated
149 UST systems (53%) were not
monitored (a few because the tanks
were abandoned), monitoring
records were not in the agency files,
or monitoring histories were not
known. For 132 cases with available
monitoring information, there were
long-time gaps, an average of 29
months, between the last monitoring
date and discovery of a leak.
These gaps in monitoring data
not only make the evaluation of leak
detection methods difficult, they also
send up a red flag that UST owners
and operators still haven't gotten the
leak detection message. While the
information in our survey is not ade-
quate to make a statement about
whether leak detection works, it does
highlight some problems. We
believe, however, that tank owner
education and consistent enforce-
ment of monitoring requirements
will give leak detection a better
chance to work.
Do Leak Detection Methods
Discover Leaks?
Overall, it appears that leak detec-
tion methods are not discovering
Summary of the Leak Discovery Methods
Leak Discovery Method
Dispenser Relocation (OR)
Monitoring Well installation (MW)
Piping Modification (PM)
Property Sale/transaction (PS)
Piping Work (PW)
Site Assessment (SA)
Site Investigation (SI)
Soil Boring (SB)
Subsurface Monitoring (SM)
Site Work (SW)
Tank closure/removal (TC, TR)
Upgrade/lining (UP)
Water Sampling (WS)
Number of sites
Total leaks discovered through site activities category
Percent of cases based on total sites '
Percent cases based on number of cases with leak discovery information 2
Inventory Control (1C)
Leak Detector (LD)
Piping Test (PT)
Tank Test (TT)
Annual leak detection equipment inspection/maintenance check (Al)
Total leaks discovered by leak detection
Percent of cases based on total sites '
Percent cases based on number of cases with leak discovery information 2
Other means (OT)
Visual (V)
Nuisance Conditions (NC)
Total leaks discovered by other methods
Percent of cases based on total sites '
Percent cases based on number of cases with leak discovery information 2
Total cases with no information on leak discovery methods
Total number of cases with leak discovery Information
Total number of sites in the database
1 With respect to 345 cases
2 With respect to 313 cases
13
223
263
76%
84%
15
4%
5%
31
35
10%
11%
32
313
345
22
-------
LUSTLine Bulletin 28
Leak Sources
Leak Source
Dispenser (D)
Dispenser & Line (DL)
Dispenser & Overfill (DO)
Above ground Piping (AP)
Piping (P)
Previous Leak (PL)
Spill (S)
Overfill (O)
Overfill / Line (OL)
Tank(T)
Tank & Dispenser (TD)
Tank & Line (TL)
Tank & Line & Dispenser (TLD)
Unknown (U)
Blank entries
Totals For Each Leak Source
(includes overlapping cases)
Total number of cases with the dispenser as leak source
Percent based on total number of sites1
Percent of cases excluding cases without information2
Total number of cases with piping as leak source
Percent based on total number of sites'
Percent of cases excluding cases without information2
Total number of cases of overfill as leak source
Percent based on total number of sites1
Percent of cases excluding cases without information2
Total number of cases with the tank as leak source
Percent based on total number of sites1
Percent of cases excluding cases without information2
Total number of cases with an unknown leak source
Percent based on total number of sites1
Percent of cases excluding cases without information2
Total number of cases with information
Total number of cases with no information
Total number of sites in the database
1 With respect to 345 cases
2 With respect to 121 cases
many leaks. (See Table 1.) There
were only 15 cases (4.8%) in which
leak detection identified a leak. This
is a very low number, but it is an
indication that if used properly, leak
detection has the potential to find
leaks. Our review of these data and
available monitoring reports high-
lights two of the main concerns with
with the use of leak detection. First,
. owners, operators, and sometimes
regulators ignore or overrule the
results of failed tests and have
another test performed (which is not
always performed by the same
tester). It is important to investigate
the failed test report before redoing
the test or accepting the result of the
retest. Second, some SIR vendors and
tank testers are incorrectly reporting
their test results. Some testers tend to
ignore excess gains and call them a
"pass." A few of the leaking sites had
previous excess-gain SIR results that
were reported as a "pass" or "incon-
clusive" by the vendor,'and no fol-
lowup was done by the tank owner
to determine the cause. Available
Number of
sites
11
1
2
1
35
1
2
7
1
54
2
154
70
18
5%
15%
41
12%
34%
12
3%
10%
60
17%
50%
154
45%
127%
records point to a few
cases where we suspect
that the leak detection
method failed to iden-
tify the leak. (The leak
discovery date and the
date of last "pass"
monitoring result were
very close.)
To evaluate the
effectiveness of leak
detection methods that
are required annually
(i.e., annual line testing,
annual tank tightness
testing), we need infor-
mation on the esti-
mated age of the leak.
This, in turn, suggests
that to detect leaks
within a reasonable
time frame, we should
encourage the use of
frequent monitoring
methods (monthly or
continuous) rather than
annual monitoring.
It appears that the
main problem with this
failure to discover leaks
is that many of the leak-
ing sites have not been
properly monitored.
For this reason, I
believe that regulatory
agencies should focus on proper
review of monitoring records and
test reports, adequate followup on
reported fail and inconclusive results,
and periodic maintenance checks of
leak detection equipment. (California
requires annual leak detection equip-
ment maintenance testing.)
What Are the Sources of UST
Releases?
Most leaks evaluated in the survey
were from tanks and piping systems.
(See Table 2.) Of the 121 cases for
which leak source information was
available, 50 percent were tank leaks
and 34 percent were piping leaks. A
total of 18 dispenser area and 12
overfill/spill releases were reported.
These data contrast with past leaking
UST site surveys that reported that
most leaks came from piping and
overfilling. Most of the leaking sys-
tems were single-walled USTs, 10 to
40 years old. There were 10 cases in
which the leak most likely came from
a double-walled tank system (less
121
224
345
than 10 years old). In these instances,
one leak was caused by a fiberglass
tank rupture (discovered during the
annual equipment maintenance
check), and two leaks were in the dis-
penser area. It is important to note
that without containment under the
dispenser, dispenser-piping leaks
and fuel releases during filter
changes are not contained and can
remain undetected for years.
Automatic tank gauging (ATG)
systems, groundwater and vapor
monitoring, and manual tank gaug-
ing (MTG) methods of monitoring
were not included in this survey.
Vapor and groundwater monitoring
and manual tank gauging are rarely
used in California. Access to ATG
test reports requires tank owner
cooperation, because these reports
are not submitted to the regulatory
agencies. However, our review of
data indicates that at some of the sur-
vey sites, an ATG system was
installed. But was it used? We do not
know. We do know that none of the
leaks in our survey was discovered
by an ATG system.
Recommendations?
Clearly, leak detection has not
become a way of life for many tank
owners/operators or leak detection
service providers. We have yet to
drive home the true function of leak
detection, which is to prevent a small
leak from becoming a big leak and,
hence, a big problem. It is apparent
that those of us who are UST regula-
tors have a good deal more work to
do. We need to pursue diligent over-
sight by regulatory agencies, proper
use and maintenance of leak detec-
tion equipment by tank owners,
adherence to test protocols, and
accurate reporting of test results by
testing companies. Is leak detection
working? As Marcel Moreau sug-
gested in his article in LUSTLine Bul-
letin #26, we will need a more
comprehensive survey on this sub-
ject that is national in scope. •
Shahla Dargahi Farahnak, P.E., is
Associate Engineer with the California
State Water Resources Control Board.
For a copy of the complete survey
report, contact Shahla at
farahnas@gwgate.swrcb.ca.gov.
23
-------
LUSTLine Bulletin 28
nicalty Speaking
by Marcel Moreau
L • Marcel Moreau is a nationally
J=- recognized petroleum storage specialist
| whose column, Tank-nically Speaking,
\ is a regular feature of LUSTLine. As
r always, we welcome your comments,
J7 questions, and suggestions regarding
fe«.-..i'...'.,.i2Vla/-ce^ discussion.
UUHflT fi&OUT TANK LINING?
If you have a steel underground
petroleum storage system that is
not protected against corrosion,
you can meet the federal December
22, 1998, UST upgrading deadline
requirements by closing your sys-
tem, by replacing it with a new cor-
rosion-protected system, or by
upgrading your existing system. The
federal regulations refer to the addi-
tion of corrosion protection to stor-
age systems that are not presently
protected against corrosion as
"upgrading." These regulations pro-
vide three options for applying cor-
rosion protection to existing storage
systems:
• Add internal lining;
• Add cathodic protection to the
outside of the tank; or
• Add cathodic protection and
internal lining.
In this article we'll explore the
options that include internal lining.
Internal Lining
The process of adding a coating to
the inside of a tank is called internal
lining. The procedure involves emp-
tying the tank of all liquids, freeing
the tank of explosive vapors, exca-
vating to the top of tank, and cutting
a hole about two feet square in the
tank top for a person to enter.
This person then cleans any
sludge out of the tank and carefully
sandblasts the entire inside surface
of the tank. The tank is then struc-
turally assessed by visually checking
for corrosion holes and split welds;
determining the thickness of the tank
wall, either ultrasonically or by
banging on the tank walls with a
hammer (not very sophisticated but,
I am told, effective); and measuring
the tank diameter to determine
whether the tank is still reasonably
round.
If the tank has a few holes,
industry standards indicate that they
can be plugged and patched, and the
tank can still be lined. If the tank has
too many holes, the walls are too
thin, or the tank is too out of shape
(an oval-shaped tank indicates that
the tank is collapsing) the tank can-
not be lined and must be properly
closed. If it is determined that the
tank is sound, a lining of epoxy or
polyester resin with a nominal thick-
ness of 1 / 8 inch is applied. The entry-
hole in the tank is then sealed, and
the tank is considered to be
upgraded with corrosion protection.
The tank must then be inspected
when the lining is 10 years old and
every 5 years thereafter.
Internal lining contractors gen-
erally provide a 1-year warranty on
workmanship and materials and a
10-year warranty against corrosion-
induced leaks. The warranty covers
fixing the hole but not cleaning up
the leak. There is no warranty
against leaks resulting from struc-
tural failure such as failed welds.
While a simple internal lining is
all that is required to meet the' regu-
lations, some companies also offer a
secondary containment retrofit
option, which provides a cost-effec-
tive way of gaining the added secu-
rity of secondary containment
without replacing existing tank sys-
tems. There are three techniques:
• Lining the tank as usual and
then inserting a flexible bladder
in the tank that becomes the
primary container for the liquid
in the tank. The space between
the bladder and the lining is
monitored with a vacuum so
that the integrity of both the
bladder and the tank wall can
be verified.
• Lining the tank as usual, then
applying a thin layer of a
porous material to the inside of
the tank, followed by a second
layer of the lining material.
This second layer of lining
material then becomes the pri-
mary container for the liquid in
the tank. Again, a vacuum can
be maintained in the porous
material that is sandwiched
between the lining layers, thus
verifying the integrity of both
lining layers.
• Building a fiberglass tank
inside an existing tank by
inserting prefabricated panels
into the tank and fastening
them together with fiberglass
cloth and resin.
A Historical Look at Tank
Lining
With the December 22, 1998, dead-
line upon us, 1998 is bound to be a
boom year for the tank-lining indus-
try. While never a prominent or
highly visible segment of the petro-
leum industry, tank lining has been
with us for almost 50 years, dating
back to the early 1950s. At the time of
UST rule promulgation, the federal
register noted that 300,000 heating
oil tanks and over 70,000 motor fuel
tanks had been lined in the previous
25 years (Federal Register, Vol. 53, No.
185, p. 37132).
For most of its life, especially in
the motor fuel storage industry, tank
lining has been largely a repair busi-
ness. Although sometimes applied as
preventive maintenance, lining was
usually a stopgap procedure used to
extend the life of tanks that had
already leaked. Tank repair is explic-
itly permitted in the federal rules, so
this aspect of tank lining is destined
to continue. Lining has also been a
long-standing technique for extend-
ing the life of the bottoms of large
aboveground tanks.
Is Tank Lining Really
Corrosion Protection?
Although we use coatings (i.e., paint)
to forestall corrosion of our automo-
24
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LUSTLine Bulletin 28
biles, we also recognize that the
paint on one side of a piece of metal
has little effect in preventing corro-
sion on the other side of the metal.
While internal corrosion is a factor to
consider with steel USTs, histori-
cally, bare steel USTs have failed pri-
marily because of corrosion working
from the outside of the tank inward.
So, how is a coating on the inside of
the tank going to help solve the cor-
rosion problem?
We're pinning our hopes on the
fact that the lining is not just mere
paint but a "thick film," with a nomi-
nal thickness of 1/8 inch. As the the-
ory goes, should the tank perforate
from the outside, the lining will have
sufficient strength to bridge the gap.
The preamble to the federal rule
acknowledges that tank lining "...as
the sole method for corrosion protec-
tion is not regarded as a permanent
upgrade, but is adequate if it contin-
ues to meet original lining design
specifications as determined by peri-
odic inspections." (Federal Register
Vol. 53, No. 185, p. 37131) In other
words, the periodic inspection
requirement at 10 years after lining
and every 5 years thereafter is an
integral part of the tank-lining
upgrade endorsed by the federal
rule. There is an implicit assumption
where, at some point in time, lined
tanks will fail to meet industry stan-
dards and will need to be replaced.
The Challenges of Tank
Lining
Anyone who has ever tried to keep a
piece of metal painted, be it on a
boat, car, or child's swing set, knows
that this procedure must be repeated
with frustrating regularity. Automo-
tive manufacturers have gotten
pretty good at keeping paint on cars,
but they use sophisticated tech-
niques to do so. The problem of
keeping a coating on steel is two-
fold: adhesion of the coating material
to the steel and thermal expansion
and contraction.
Making certain that a coating
adheres to steel properly requires an
extremely clean surface, completely
free of scale, oil, or any corrosion
products, and a certain amount of
surface roughness'to give the coating
something to grab on to. This is why
prior to the application of the lining,
the inside of the tank must be sand-
blasted to "white
metal" (a specific
level of sandblasting
defined by the Steel
Structures Painting
Council), and the lin-
ing must be applied
within 8 hours after
the blasting proce-
dure (to minimize
the opportunity for
corrosion of the
metal to take place).
Most bulk stor-
age fuel facilities use
aboveground storage
tanks; seasonal vari-
ations in the tempera-
ture of fuel stored in
aboveground tanks are much greater
than those of fuel stored in under-
ground tanks. In many parts of the
country, maximum summer/winter
temperature differentials of 20 to
30°F are to be expected between the
product in the ground and the prod-
uct delivered from aboveground
tanks. Imagine sitting cozily in a hot
tub half full of 110° water and then
having a truck fill the tub the rest of
the way with 80° water, and you can
begin to appreciate the meaning of
thermal shock. Such rapid changes in
the temperature of the tank contents
cause the tank wall to shrink or
expand. The coefficient of expansion
and contraction of the lining material
must be nearly identical to that of the
metal or else the differential move-
ment will tend to cause the coating to
become unglued.
What Do Fire Officials Think
About Tank Lining?
Historically, fire officials have been
of two minds with regard to tank lin-
ing. The two dominant flammable
liquid storage codes in this country
are the National Fire Protection
Association's (NFPA) Code 30,
"Flammable and Combustible Liq-
uids Code," and Code 30a, "Auto-
motive and Marine Service Station
Code," and the International Fire
Code Institute's (IFCI) Uniform Fire
Code Article 79, "Flammable and
Combustible Liquids." The NFPA
has generally been silent on the sub-
ject of tank lining, presumably leav-
ing the matter to the judgment of
local officials. The IFCI, which is a
consensus organization, has debated
Tank liner applying coating to the inside of a tank.
the issue and, to date, has been reluc-
tant to accept tank lining as a repair
procedure.
The development of the IFCI
position, however, appears to have
been a less than scientific process. A
report prepared on behalf of USEPA
("A Survey of Fire Service Position
Regarding Repairs to Underground
Storage Tank Systems," prepared by
Fred C. Hart Associates, Inc., dated
June 5,1987) and intended to gather
information for formulating the fed-
eral rule indicates quite strongly that
the controversy surrounding the
Uniform Fire Code position on tank
lining came about because parties
with financial interests (i.e., tank
manufacturers) tried to deal a blow
to their competition (i.e., tank liners).
The report points out that none of
the fire departments contacted had
any "engineering data to support
their position," (p. 11) either for or
against tank lining, and that individ-
ual opinions appeared to be based on
"supposition and personal prefer-
ence" (p. 10).
Be that as it may, since the 1991
edition of the Uniform Fire Code
appeared, repair of leaking tanks by
any method has not been allowed.
Tank lining is viewed strictly as a
method of "protecting the (tank)
interior from corrosion or providing
compatibility with a material to be
stored." Since at least 1988 (the earli-
est edition of the code that I have
handy), the code has required that
tank lining be used in conjunction
with either cathodic protection or
corrosion-resistant materials of con-
struction. Thus in those portions of
• continued on page 26
25
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LUSTLine Bulletin 28
• Tank Lining from page 25
the country where the Uniform Fire
Code is enforced (primarily the west-
ern United States), the federally
allowed option of upgrading by tank
lining only is not permitted.
UL and Tank Lining
Underwriter's Laboratories (UL) has a
methodology (Subject 1856) for evalu-
ating both tank-lining materials and
the tank-lining process. A UL "Sub-
ject" has not undergone the extensive
external review and examination
required for an official UL "Stan-
dard." The evaluation of lining mater-
ial described in UL 1856 includes:
• Immersing samples of the lin-
ing material in an assortment of
test liquids and looking for
changes in the physical proper-
ties of the material;
• Testing for absorption or disso-
lution of the lining in the test
liquids;
• Dropping a 1.18-pound steel
ball from a height of 6 feet to
test the bonding of the lining to
a steel plate; and
• Testing for corrosion beneath
the lining.
Testing the lining process, as
described in UL 1856, involves bury-
ing a "worst case" tank (i.e., a tank
with the maximum number of holes
allowed by the lining standard),
plugging and patching the holes,
applying the lining, and then con-
ducting an air-pressure test on the
tank. The tank excavation is then
filled with water to grade for 24
hours, and a vacuum is applied for 1
minute while the tank is submerged.
The lining process tests, con-
tained in UL Subject 1856 (November
1992), parallel the testing required by
UL Standard 1746 at the time that UL
Subject 1856 was developed. UL 1746
is the standard that applies to new
steel tanks that achieve corrosion
protection through the application of
a thick coating (cladding) on the out-
side of the tank.
Both of the lining standards
commonly used in this country,
American Petroleum Institute (API)
1631, "Interior Lining of Under-
ground Storage Tanks," and
National Leak Prevention Associa-
tion (NLPA) 631, "Entry, Cleaning,
Interior Inspection, Repair, and Lin-
ing of Underground Storage Tanks,"
contain lining material evaluations
that are similar to the one in UL 1856.
UL 1856 is the only evaluation that
looks at the completed lining process
on an actual tank.
To be in conformance with an
industry standard and thus the fed-
eral rule, tank liners must document
that their lining material has passed
the tests specified in either API 1631,
NLPA 631, or UL 1856. Industry
standards do not specify that the lin-
ing process must be evaluated,
although some lining companies
have achieved a UL 1856 listing.
• continued on page 28
A Tank Lining Inspection Checklist*
Ask to see a copy of the lining applicator's insurance policy.
Ask for references and call a few. Ask whether the work was done on schedule, whether the workers were clean and neat, and
whether the site was left in a clean condition.
Ask to see documentation that the tank lining crew members have received the appropriate OSHA training (at a minimum, 40-
hour health and safety plus annual 8-hour refresher courses) and have experience in this line of work.
Ask for documentation that the lining material has been tested and is compatible with the liquid you plan to store (including
oxygenated fuel).
Ask who will be responsible for disposing of the tank bottom sludge (which could well be a hazardous waste). If you, the tank
owner, are responsible, be sure disposal is handled properly.
Ask to review the results of the structural assessment of the tank Before the workers proceed to apply the lining. The struc-
tural assessment usually involves checking the metal thickness (typically by pounding on the tank walls with a hammer or
measuring with an ultrasonic gauge), usually after a preliminary sandblasting to get a good view of the metal.
Verify the amount and type of sand used for sandblasting. A 10,000-gallon tank typically requires at least a ton (twenty 100-
pound bags) of 18 grit abrasive. Ask what is going to happen to the sand after the blasting is complete. If your tank held leaded
gasoline at some point, the sand/metal mixture may be a hazardous waste. If the sand is to be disposed of at your facility (i.e.,
as part of the backfill for the excavation required to reach the top of the tank), have the tank-lining company certify that the
material is not a hazardous waste, or add the cost of disposing of the material properly to your cost of doing this work.
Verify that the pressure used to sandblast is at least 90 psi.
Verify by looking through the hole in the tank top that at least the portion of the tank you can see has been blasted to "white
metal" before the lining is applied. A "white metal" surface should have a "gray-white uniform metallic color" and should be
free of "all oil, grease, dirt, visible rust, scale, corrosion products, oxides, paint or other foreign matter."
Verify that there is adequate lining material on hand to do the lining. A 10,000-gallon tank typically requires about 60 gallons
of lining material.
Verify that the lining will be applied within 8 hours of sandblasting the tank and before any visible rusting occurs.
After the lining has cured, verify that the tank has been reentered and that the lining has been tested for thickness, hardness,
and defects.
Be sure to obtain the tank-lining warranty paperwork.
* ADAPTED FROM A usi PREPARED BY TEHI BAHRYCH, USEPA - REGION 8.
26
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LUSTLine Bulletin 28
from 'Robert N. Renkes, Executive Vice President, Petroleum Equipment Institute
Let's Be Careful Out There
Underground storage tank contractors tell us
they expect that 1998 will be the busiest year yet
for companies involved in underground stor-
age tank work. Contractors expect that their crews will
be called upon to work long days this year as tank
owners prepare their sites to comply with EPA's 1998
deadline. Pressure to get the job done quickly and effi-
ciently will grow with each passing day. As a result,
new and relatively inexperienced workers will be hired
by some companies to handle the demand.
With so much work to do, it's easy to put safety
on the back burner. But that should never happen.
Three recent tank-related accidents in California in
which one man was killed and several others were
injured serve as poignant reminders that UST work is a
dangerous profession that requires constant attention
to the safe and proper way to do the job. Over the
years, PEI has collected numerous accounts of acci-
dents that have occurred throughout the country. I'll
share some examples- of these accounts with you in
hopes that they will serve as a reminder that safety
should be foremost in everyone's mind. Remember,
these stories are true. It is the contractor's responsibil-
ity to make certain that safety is a number one priority
on all job sites.
Testing Tanks and Lines
• A tank was air tested aboveground prior to installa-
tion. The mechanic used a vacuum gauge instead of a
pressure gauge. As a result, tremendous pressure
developed, blowing out one end of the tank with suffi-
cient force to damage a truck and a nearby building.
• A foreman was pressure-testing a tank when a plug
blew out of a tank opening and struck him in and
around his left eye.
Lining Tanks
• While in the process of relining an UST, a 4-inch rub-
ber Expando plug was placed in the product line from
inside the tank. During the sandblasting procedure, an
employee in the tank hit the Expando plug, which was
located directly above him. The Expando plug eventu-
ally worked itself loose and fell out, causing the
employee to be soaked with fuel.
• Two workers were preparing to line an under-
ground tank. They had driven 150 miles in a shop truck
to the tank site. Before cutting an entry hole in the top
of the tank, they evacuated the vapors in the tank. Then
one of the workers held an explosimeter over the top of
the fillpipe to determine if there were ignitable vapors
present. They did not, however, first test the accuracy
of the explosimeter by holding it over the opening of
the gas tank of the shop truck. The explosimeter indi-
cated that the vapors in the underground tank were
minimal and that it was safe to proceed. But when one
of the workers started the power saw and began to cut
the entry hole, there was a spark and an explosion. One
worker was killed and the other was seriously injured.
Investigators determined that the explosimeter had
been damaged from bouncing around in the back of the
shop truck during the 150-mile trip to the tank site.
Removing Tanks
» Several very old tanks were being removed from the
ground. Each contained 20 to 30 gallons of product.
One of the tanks ruptured as it was being removed
from the hole, spilling product onto the asphalt sur-
rounding the excavation. The backhoe operator
attempted to soak up the product by covering it with
the soil he had removed from the excavation. Some
time later, as the backhoe operator began to collect the
contaminated soil with the backhoe, the loader bucket
apparently scraped the asphalt. Sparks caused by the
friction ignited the gasoline fumes emanating from the
soil. As fire engulfed the backhoe, the operator jumped
through flames to safety.
• A crew had been subcontracted to remove USTs
from a gasoline-marketing facility. Because of the size
of the buried tanks, a crane with a large boom had to be
used. One of the tanks was buried near a high-voltage
(36,000 V) wire. As the operator swung the boom
around to position it over the tank, the boom continued
to move forward for a short distance after the operator
had actually stopped it with his controls. The boom
touched the wire for a second and then bounced back
to its position over the tank. The operator, who was
Wearing leather gloves and holding rubber control han-
dles, was knocked out of the control cab by the electric
shock. The general contractor who was standing on the
ground and leaning against the stabilizer on the crane
was electrocuted.
Decommissioning Tanks
• The top of an empty UST, which had been inerted
with dry ice, was uncovered while the tank was still in
the ground. In order to render the tank nonhazardous
for transportation purposes, the tank was triple-rinsed
according to state environmental agency requirements.
The tank openings were sealed, as required by city fire
regulations. The tank was removed from the ground,
placed on a flatbed trailer, and transported to a tank
disposal yard. The disposal yard would not accept the
tank with the ends on it, so the crew transported the
tank to the plumbing contractor's storage yard. The
tank sat in the yard for several days. Fire officials spec-
ulate the plumbing firm considered the tank safe after
it had been triple-rinsed. During that time, however,
the seals were removed from the tank, allowing the
gasoline vapors and air to mix again. A welder was
• continued on page 28
27
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LUSTLinc Bulletin 28
I fUe^X A/«&* continued from page 27
sent to cut the ends off of the tank with his acetylene
torch so that the tank could be returned to the disposal
yard. The tank was still chained to the flatbed trailer
when the top blew off the tank. The explosion flung the
welder off the truck, over an 8-foot chain-link fence,
and into the street. The blast killed him instantly.
• A workman was cleaning out an UST. After the tank
was scrubbed, and before it was abandoned in place by
being filled with sand, the workman used a ladder to
climb down into the vessel. He carried an electric lamp
and an electric saw—both connected to an extension
cord—into the tank. (Investigating fire officials were
baffled as to what the man hoped to accomplish by
doing this.) Fumes lingering.in the tank ignited and sur-
rounded the workman in flames. He suffered second-
and third-degree burns over 86 percent of his body.
Installing Underground Storage Systems
* A veteran mechanic was replacing an old steel line
with new fiberglass piping. The line was drained the
first day he was on site. The next morning when he
returned to complete the job, he did not test the line.
The worker assumed the line would be free of vapors,
because it had been left open all night. He elected to cut
it with an electric band saw. A small flash fire occurred
when the accumulated vapors were ignited by a spark
from the saw.
• An installation crew was cleaning up a job site. A
manhole had just been cleaned out and the cover had
not been replaced. The crew chief was walking back-
ward, blowing debris off the concrete with an air com-
pressor hose. He backed into the open manhole and
broke his rib.
• A blister formed on the palm of a laborer's hand
while he was digging in a tank hole at a service station.
Later, while he was installing new fiberglass piping,
the blister broke, and his hand became infected when
fiberglass glue entered the open cut. Although the
employee was issued cloth gloves, he was not wearing
them on this occasion, because he was fearful that he
would drop the fiberglass pipe and cause it to crack or
fracture. The laborer spent 7 days in the hospital recov-
ering from blood poisoning. •
In the next issue o/LUSTLine, a health and safety spe-
cialist will delve further into issues of UST/LUST-
related safety.
• TANK-nically Speaking from
page 26
Consumer Tips
As with most other underground
storage system work, quality control
is a big issue. The three most impor-
tant things you should demand if
you are having a tank lined are;
1) skilled, conscientious workers; 2)
skilled, conscientious workers; and
3) skilled, conscientious workers.
Good workmanship is critical
because verifying that work is being
done according to industry stan-
dards requires diligent oversight and
is difficult for the average tank
owner or regulator to do. Entering
underground tanks to check on the
work is risky business that requires
OSHA confined space entry training.
There are a few things that can be
checked (see the checklist on page
26), but, by and large, a tank owner's
best bet is to hire a reputable contrac-
tor who has been in business for
quite a while, and who is planning to
be around at least until the warranty
on the lining runs out. Contractor's
liability insurance is also something
that I would require if I were hiring a
tank-lining company.
Like many other aspects of tank
work, tank lining can be hazardous.
Although the overall safety record of
the tank-lining industry is very good,
accidents can happen. One man died
and three others were injured in two
recent tank-lining-related accidents
in California. Be sure that the con-
tractor doing the work can demon-
strate that the workers in the tank
have the required OSHA training.
Would I Choose This Upgrade
Option?
Over the last few years I have had
occasion to talk to hundreds of tank
owners (most of whom own or oper-
ate only a few tanks) about the 1998
upgrading requirements. After
describing the options of lining,
cathodic protection, and replacement,
I am often asked the question, "What
would you do if you owned a tank?"
Let me preface my answer by
saying that I would feel better if I
had some hard data to support my
upgrading decision. It would be nice
if there were a study that had been
conducted by an independent third
party that had randomly selected
several hundred lined tanks and sev-
eral hundred tanks that had been
retrofitted with cathodic protection a
decade earlier. It would be nice if
that third party had thoroughly eval-
uated these tanks to see how they
were faring. It would be nice. But, to
my knowledge, such a study does
not exist. Instead, what we have are a
few surveys indicating that as far as
anybody knows, things are okay.
Thus, my answer usually goes
something like this: We don't have
any independent engineering studies
that provide hard data on the actual
performance of cathodic protection
or tank lining, so we don't really
know exactly how well these tech-
nologies work in the long run. I've
heard good and bad stories about
both cathodic protection and lining.
But there are people who do know.
The major oil companies have been
using lining since the 1950s; they
used cathodic protection in the 1960s
and 1970s; in the 1980s most of them
went to large-scale replacement of
their tank populations.
The major oil companies, of
course, have the money to replace
their storage systems, and they prob-
ably plan to be in business for the
long haul. If you are not a major oil
company, however, and you are only
planning to use your storage tank(s)
for a few more years, then I think
upgrading with either lining or
cathodic protection makes sense. If
you are planning to store petroleum
underground for a while and want to
have an asset rather than a potential
liability when you're done, then
replacement is the way to go. •
28
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LUSTLine Bulletin 28
from the ASTSWMQ Tanks Subcommittee
Coast to Coast is provided as a regular feature o/LUSTLine to update state and federal UST, LUST, and cleanup fund person-
nel about the activities of the Association of State and Territorial Solid Waste Management Officials' (ASTSWMO) Tanks
Subcommittee. If you want to learn more about the Tanks Subcommittee, contact the Subcommittee Chair, Scott Winters (CO)
at (303) 620-4008, or Stephen Crimaudo (ASTSWMO) at (202) 624-7883.
Tanks Subcommittee
• The Tanks Subcommittee, along
with all of the Task Force members,
completed work on the "UST Report
Card on the Federal UST/LUST Pro-
gram" (a review of the program, its
goals, achievements, and shortcom-
ings), which is now in print. Copies
may be obtained by contacting Steve
Crimaudo.
• At the ASTSWMO annual meeting,
held in Arlington, Virginia, on Octo-
ber 27-28,1997, Subcommittee mem-
bers met with representatives of EPA
OUST to discuss current issues,
including the 1998 upgrade deadline,
results of the May 1997 enforcement
sweep, OUST's planning for 1999 and
beyond, preparation of the 1998 OUST
National Conference, MTBE issues,
and the budget. The chairpersons for
the four different Subcommittee Task
Forces met at this conference to lay out
a strategy and agenda for 1998.
• Each of the four Task Forces is cur-
rently looking for new members. If
you are interested in taking part in the
work of any of the Task Forces, or if
you have questions or comments on
overall Subcommittee activities, con-
tact Steve Crimaudo or Scott Winters.
UST Task Force
• The UST Task Force has been
working, primarily, on issues relating
to the 1998 UST technical standards
for the upgrading of USTs.
• The Task Force has begun prepar-
ing for a presentation on managing
hazardous waste/hazardous sub-
stance USTs, which will be given at
EPA's National UST/LUST Confer-
ence in March. This presentation will
highlight the similarities and differ-
ences between managing chemical-
storage USTs and petroleum-storage
USTs. The LUST Task Force will also
be participating in this session, pre-
senting issues on site assessment at
closure, reporting, site investigation,
and cleanup associated with these
types of tanks.
For more information on UST Task Force
activities, contact the Task Force Co-chairs,
Paul Sausville (NY) at (518) 457-4351 or
Dale Marx (UT) at (801) 536-4131.
LUST Task Force
• The LUST Task Force continues to
review several innovative technolo-
gies.
• Members of the Task Force are
ongoing participants of the
EPA/OUST MTBE workgroup. This
workgroup will hold a "states only"
meeting on MTBE issues at the
National UST/LUST Conference in
March.
• Members of the Task Force are par-
ticipating in ASTM E50.01 Subcom-
mittee work on two new standards:
"Evaluating Remedial Decisions" and
"Integrated Site Management."
• The Task Force drafted a letter to
EPA on the new EPA Monitoring by
Natural Attenuation Policy.
• Planned projects include produc-
ing a document on possible environ-
mental indicators states may use for
LUST programs, reviewing and com-
menting on the Texas and Florida risk
and RBCA reports, and preparing to
speak on site assessments, notification,
and remediation of hazardous sub-
stance/hazardous waste USTs at the
National UST/LUST Conference.
For more information on LUST Task
Force activities, contact the Co-chairs,
Kevin Kratina (NJ) at (609) 633-1415 or
Richard Spiese (VT) at (802) 241-3880.
State Cleanup Funds Task Force
After completing a very successful
Sixth Annual State Fund Administra-
tors Conference in June in Sacramento,
California, the State Cleanup Funds
Task Force is busy planning for the
Seventh Annual State Fund Adminis-
trators Conference, which will be held
in Austin, Texas, on June 22-24,1998.
The Task Force met in Washington,
D.C., on January 8 and 9, 1998, to
prepare the draft agenda for this con-
ference. With the enthusiastic par-
ticipation of the planning committee,
this year's conference is shaping up to
be the best one ever. If you have ideas
for additional sessions for this confer-
ence, please contact a member of the
Task Force. Also, look for this year's
State Funds Questionnaire, which will
be sent to State Fund Managers in
May.
For more information on the State Cleanup
Funds Task Force activities or on the Sixth
Annual Conference, contact the Co-chairs,
Dan Neal (TX) at (512) 239-2258 or
George Matthis (NC) at (919) 733-9413.
TIE Task Force
• The Training and information
Exchange (TIE) Committee performed
the lion's share of the work in com-
pleting the "Report Card" project.
• The Task Force is coordinating and
moderating the session on Hazardous
Substance Tanks at the National
UST/LUST.
• The Task Force is working hard to
ensure the successful planning and
implementation of the ASTSWMO
Mid-Year meeting, which will be held
in Kansas City, Missouri on April
20-22.
• The TIE Task Force continues to
work on and update ASTSWMO's
Internet home page.
If you have questions or comments on TIE
Task Force activities, call Task Force
Chair Kathy Stiller (DE) at (302) 323-
4588. . • • • • . , . .
29
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LUSTLine Bulletin 28
States/ASTSWMO Form
MTBE Workgroup
by Jeff Kuhn
The ASTSWMO LUST Task Force began organizing
an MTBE Workgroup in early 1997 in response to a
increasing need for information and discussion on
MTBE issues. The idea of a workgroup grew out of the '
participation of state representatives in the EPA-spon-
sored MTBE Task Force, which was organized to study the
magnitude of the MTBE problem and discuss the experi-
ences and concerns of regulatory agencies and industry.
Since that time, members of the LUST Task Force have
continued to gather information for dissemination to the
states. The goal of the workgroup is to function as a clear-
inghouse for new information on MTBE and to get the
word out by way of a quarterly newsletter. The newsletter
will include information on state and federal government
activities and policies regarding MTBE, new publications
and research papers, the results of various surveys that are
currently under way, and postings of internet web sites
where additional information can be found.
A tremendous amount of research activity is currently
under way through the efforts of EPA, API, industry, states,
city municipalities, and private organizations with an inter-
est in contaminant fate and transport and public health.
Although a great deal of information on MTBE has become
available in the last two years, little is known about the long-
term effects on humans from exposure to low concentrations
of MTBE and other fuel oxygenates. The presence of MTBE
in the environment has become a national public health and
research concern and requires greater focus and coordina-
tion on the part of all parties involved. We hope that our
efforts will lead to a greater level of communication among
interested parties and that we will be able to assist states in
finding much needed resource information on MTBE-
related topics and case-incident studies.
The workgroup welcomes the input of all individu-
als and organizations involved in the MTBE issue and is
soliciting help from other state representatives who are
interested in participating in work efforts. To contribute
information to the ASTSWMO MTBE newsletter, to par-
ticipate in the workgroup, or to receive the newsletter,
contact Jeff Kuhn, Montana DEQ Petroleum Release Sec-
tion (406) 444-5976 (jkuhn@mt.gov), or Pat Ellis, Delaware
DNREC-UST Branch (302) 323-4588
(pellis@DNREC.STATE.DEC.US).
Topics covered in the upcoming issue of the
newsletter include:
EPA MTBE Fact Sheets
MTBE Surveys in Progress
EPA's Drinking Water Health Advisory
Fuel Oxygenates and Testing Requirements
Compatibility Issues
MTBE News from the States
Treatment Technology Research
Legislative Activity on MTBE
Jeff Kuhn is with the Montana DEQ Petroleum Release
Section and is a member of the LUST Task Force.
MTBE Compatibility References
Alexander, James Ev Edward P. Ferber,
and William M. Stahl, 1994. Avoid Leaks
from Reformulated Fuels, Fuel Reformula-
tion, pp. 42-46.
Aloisio, Salvatore, 1994. Performance of
Fluorocarbon Elastomers in MTBE/Fuel
Blends, SAE Technical Paper Series No. 940956,
SAE International, Warrendale, PA, 20 pp.
Alpha/Owens-Corning, 1996. A letter from Bruce Curry
(Alpha/Owens-Corning) to Bill Schneider (Fluid Contain-
ment), September 5,1996,2 pp.
American Petroleum Institute, 1985. Storing and Handling
Ethanol and Gasoline-Ethanol Blends at Distribution Ter-
minals and Service Stations, API Publication 1626, Wash-
ington, D.C., April 1985, 6 pp.
American Petroleum Institute, 1986. Storing and Handling
Methanol and Gasoline-Methanol Blends at Distribution
Terminals and Service Stations, API Publication 1627,
Washington, D.C., August 1986, 6 pp.
American Petroleum Institute, 1990. An Engineering
Analysis of the Effects of Oxygenated Fuels on Marketing
Vapor Recovery Equipment, Final Report, Washington,
D.C., September 1990, 38 pp.
Curran, Sullivan D., 1997. Permeability of Synthetic Mem-
branes for the Containment of Petroleum Products. Fiber-
glass Tank and Pipe Institute, Houston, Texas, March 1997,
5pp.
Douthit, Walter H., Brian C. Davis, E. De Lieu Steinke, and
Helen M. Doherty, 1988. Performance Features of 15%
MTBE/Gasoline Blends. SAE Technical Paper Series
#881667, SAE International, Warrendale, PA.
Fluid Containment, 1997. MTBE and FRP Underground
Storage Tanks, a brief technical update from Fluid Contain-
ment, October 8,1997,2 pp. with many attachments.
Hotaling, Andrea C., 1995. Evaluating Nonmetallic Materi-
als' Compatibility with MTBE and MTBE+ Gasoline Ser-
vice, in American Energy Week '95 Pipelines, Terminals
& Storage, and Reformulated Fuels Conference Proceed-
ings, Book 2, pp. 118-126.
ICF Incorporated, 1997. Survey of Flexible Piping Systems,
Fairfax, VA, March 1997,15 pp.
Lang, G.J. and F.H. Palmer, 1989. Use of Oxygenates in
Motor Gasoline, in Gasoline and Diesel Fuel Additives - Criti-
cal Reports in Applied Chemistry, K. Owen (editor), Vol. 25,
John Wiley & Sons, London, UK.
Owens-Corning, 1995. Open Letter to Owens-Corning
Tank Customers, April 14, 1995, from Owens-Corning
World Headquarters, Toledo, Ohio, 2 pp.
Smith, Gordon M., 1995. The Evolution of Fuel: A Disserta-
tion on MTBE and Elastomers, in American Energy Week
'95 — Pipelines, Terminals & Storage, and Reformulated
Fuels Conference Proceedings, Book 2, pp. 212-219.
Smith Fiberglass Products Inc., 1996. Just the Facts, Smith
Fiberglass Products, Inc., Little Rock, Arkansas, 4 pp.
Sun Refining and Marketing Company, 1988.15% MTBE
Waiver Request, submitted to Lee M. Thomas, United
States Environmental Protection Agency, Washington,
D.C., March 14,1988.
30
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LUSTLine Bulletin 28
'98 Deadline Press Conference
On December 22, 1997, EPA offi-
cials Timothy Fields, Acting Assis-
tant Administrator of the Office of
Solid Waste and Emergency
Response, and OUST Director
Anna Virbick joined Jane Nishida,
Secretary of the Maryland Depart-
ment of Environment, and repre-
sentatives from five petroleum
industry associations (American
Petroleum Institute, Petroleum
Marketers Association of America,
Society of Independent Gasoline
Marketers of America, Service Sta-
tion Dealers of America, and
National Association of Conve-
nience Stores) in a joint press con-
ference to remind UST owners and
operators that the deadline for
upgrading, replacing, or closing
substandard tanks was exactly one
year away. Speakers stressed their
support for the deadline and urged
owners and operators who have
yet to comply to begin work now in
order to meet the deadline. CNN
and C-Span cable broadcast the
program, and a number of print
media—particularly trade press—
provided coverage.
Letter to Oil Company
Executives
In November 1997, OUST sent a let-
ter to executives of about 400 small
and large petroleum marketing
firms across the country reminding
them that the 1998 compliance
deadline is only one year away.
OUST included a list of publica-
tions and other materials available
in quantity to help companies
understand the UST regulations
and the 1998 requirements.
MTBE Fact Sheets
OUST has just published the first
three in a series of fact sheets of on
methyl tertiary butyl ether (MTBE).
MTBE Fact Sheets #1: Overview
(EPA-510-F-98-001), #2: Remediation
Of MTBE-Contaminated Soil And
Groundwater (EPA-510-F-98-002)
and #3: Use And Distribution Of
MTBE And Ethcmol (EPA-510-F-98-
003) are available from NCEPI at
(800) 490-9198 or can be down-
loaded from OUST's web page at
http:/ / www.epa.gov/OUST/mtbe.
Correction
The publication number for Con-
trolling UST Cleanup Costs: Fact
Sheets, which appeared in the
November 1997 LUSTLine has been
changed. The new number for this
series of 1992 fact sheets, which has
been reissued with an update page,
is EPA-510-F-98-008. Note: These
fact sheets are not available on the
OUST home page.
OSWER Directive on Monitored
Natural Attenuation Released
OUST announced the release of a
new OSWER directive entitled Use
of Monitored Natural Attenuation at
Superfund, RCRA Corrective Action,
and Underground Storage Tank Sites.
(See "Natural Attenuation..." arti-
cle on page 5.) OUST distributed
hard copies of the directive to
regional and state UST program
offices; other OSWER offices also
distributed copies. The directive is
available in several electronic for-
mats from EPA's web site; the
address is http://www.epa.
gov/swerustl / directiv/ d9200417.
htm. Questions about this new
guidance can be directed to Hal
White or Dana Tulis.
LU.S.T.LINE
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We welcome your comments and suggestions on any of our articles.
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31
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EPA Issues MTBE Drinking Water
Advisory
-f
1
\dvice and Health Effects An^ysij^on Meth\jJ.]>te£tiary-Butyl Ether
(MTBE), EPA 822-F-97-008. Th|^recommenda|ito^ijhis:ia4visory
arc based primarily on taste Sad-odor thresholds^ The Advisory
states that drinking water containing ^/BE.xcavteati.ans-in the
range of 20 to 40 ;
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