New England Interstate
Water Pollution Control
Boott Mills South
1OO Foot of John Street
Lowell, Massachusetts
                                        Bulletin 48
A Report On Federal & State Programs To Control Leaking Underground Storage Tanks
20  Years  of  LUST  Busting
The Changes, the Joys, the Frustrations...the Future?
by Patricia Ellis

    Buried fuel tanks had been
    leaking for years—proba-
    bly for as long as they
had been buried. Finally, in
1983, the CBS program 60
Minutes aired a story
called "Check the Water,"
which brought national
attention to the effects of
leaking underground
storage tanks. In 1984,
Congress passed a new
law, requiring the U.S. EPA
to develop a regulatory pro-
gram to prevent, detect, and
clean up releases from UST sys-
tems to protect human health and
the environment. On September
23,1988, U.S. EPA issued com-
prehensive regulations (Federal
Register, 1988) affecting owners
and operators of UST systems
throughout the United States.
  The regulations went into effect on
December 22, 1998, and tank owners were
given ten years to meet some of the equipment compli-
ance deadlines. The regulations incorporate three
broad strategies:
 • Identify and then correct faulty or leaking tanks

 • Reduce the incidence of future releases by man-
  dating minimum operating and performance

 • Minimize hazards from releases by mandating a
  standard release investigation, response, and cor-
  rective action procedure
                 • continued on page 2
                           Time flies when
LUST Busting
         U Strong Actions and Creative Solutions
         60 OUST UPdate

           Age-Dating Releases at LUST Sites: Part 1—Lead Fingerprints
           Collecting Reliable Soil-Gas Data—Vapor Intrusion FAQs

           Vapor Release Assessment Techniques—Vermont
           Thoughts on Small-Time Vapor Releases
           Spill Buckets: Mistaken Expections?

           Remote-Earth Testing of Galvanic Cathodic Protection
           Shell U.S./Motiva to Phase Out MtBE in Gasoline

           Enhanced UST Compliance in New Jersey
           FAQs from the NWGLDE

LUSTLine Bulletin 48 • November 2004
 120 Years from page 1
    The third area is meant to streamline
and standardize the ways in which opera-
tors respond to suspected and confirmed
releases from USTs.  The two subparts of
this section deal with release reporting,
investigation  and  confirmation,  and
release response and corrective action.
    Because of the large regulated uni-
verse of USTs  at the beginning of the
program (over two million tanks), EPA
designed the program to be implemented
by the states. Armed  with the new federal
regulations, the states were tasked to
develop programs to manage the UST
    While I've only been with the UST
program for 15 years, in honor of this
anniversary, I  would  like to take this
occasion to reflect on the life and  times of
the LUST side of the  tanks program,
starting with the advances in cleanup

20 Years of Technology
Early LUST cleanups consisted pri-
marily of three methods. If contami-
           Ellen Frye, Editor
          Ricki Pappo, Layout
     Marcel Moreau, Technical Advisor
   Patricia Ellis, Ph.D., Technical Advisor
 Ronald Poltak, NEIWPCC Executive Director
     Lynn DePont, EPA Project Officer
 LUSTLine is a product of the New England
 Interstate Water Pollution Control Commis-
 sion (NEIWPCC). It is produced through a
   cooperative agreement (#1-830380-01)
     between NEIWPCC and the U.S.
    Environmental Protection Agency.
   LUSTLine is issued as a communication
      service for the Subtitle I RCRA
   Hazardous & Solid Waste Amendments
       rule promulgation process.
    LUSTLine is produced to promote
 information exchange on UST/LUST issues.
 The opinions and information stated herein
  are those of the authors and do not neces-
   sarily reflect the opinions of NEIWPCC.
     This publication may be copied.
     Please give credit to 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 states of Connecticut, Maine,
     Massachusetts, New Hampshire,
   New York, Rhode Island, and Vermont.

  Boott Mills South, 100 Foot of John Street
        LoweU, MA 01852-1124
        Telephone: (978) 323-7929
          Fax: (978) 323-7919

   4J§ LUSTLine is printed on Recycled Paper
nation  was  shallow,  you could
overexcavate and dispose of contam-
inated soils—"dig and dump,"  or
"muck and truck." If groundwater
was impacted, you could recover free
product (normally by hand-bailing
or mechanical skimming, or one- or
two-pump groundwater pumping.
    But pump-and-treat  was the
main way to clean up contaminant
plumes. Pump-and-treat seemed like
a "forever" type of corrective action,
because you could  pump, and pump,
and pump, and the site still wouldn't
clean up, because the petroleum con-
taminants sorbed to the soils and
only slowly released to the ground-
water. Whether or not  you could
manage to close a LUST project with
pump-and-treat was highly depen-
dent on the cleanup goals for the site.
If you had to  meet an  MCL, you
could be pumping forever.
    Shortly after I joined  the  pro-
gram, we began  to see more and
more ex-situ bioremediation of exca-
vated soils. It seemed to be  consider-
ably  cheaper   than  paying  for
disposal, but you  needed sufficient
space and time for  the bugs to do the
cleanup. In Delaware, we maintained
a "Dirty Dirt List" to keep track of
the soil  piles. Keeping the covers on
the piles intact was a nuisance, and
letting the contractors and  responsi-
ble parties know that a big mound of
dirt next to the former tank pit was
not really a bioremediation cell and
probably  wouldn't remediate very
well that way, was  a nuisance.
    With a little guidance, however,
ex-situ bioremediation was a reason-
ably inexpensive,  effective technol-
ogy. Of my biopiles, I had only one
stolen, and one attempted escapee
was chased for a day, apprehended,
and returned to where it was sup-
posed to be.
    In-situ bioremediation of soils
and groundwater came into vogue at
about the  same time. Unfortunately,
in our experience,  not everyone was
good at designing and operating an
in-situ  bioremediation project,  so
some of these projects were not very
    Pump-and-treat with soil-vapor
extraction (SVE). SVE. Air sparging,
Air sparging with SVE. Biosparging.
All were introduced into our toolbox
to give us a few additional weapons
for cleanups, and they are  still com-
monly used. Various configurations
of dual-phase/multiphase extraction
have proven effective in tighter soils
where some of the technologies that
rely on the soil's ability to  move
fluids are ineffective, removing a
combination of petroleum vapors,
free-phase product, adsorbed prod-
uct, and dissolved phase.
    The U.S.  EPA Office of Solid
Waste and Environmental Remedia-
tion (OSWER) Directive on Moni-
tored  Natural   Attenuation  was
issued in  1999, providing guidance
on how  to evaluate and monitor nat-
ural attenuation sites. It differed from
some of the other guidance  being
issued at the time in that bioremedia-
tion was stressed—other processes,
such as dispersion, diffusion, and
dilution, or chemical or mechanical
destruction were not included. A
lot of sites were eliminated from con-
sideration of this remediation option
when, due to its resistance to bio-
degradation, large amounts of MtBE
were found at the release site.
    Various oxidation technologies
are among the newer tools in our
toolbox. They have the advantage of
being relatively quick technologies,
although not necessarily cheap, and
they work reasonably well for the
fuel oxygenates.  They can help  us
meet the goals of faster cleanups.

What Chemicals Are We
Looking At?
Life was simple in the early days—
most states  looked  at  benzene,
toluene, ethylbenzene, and xylene
(BTEX), or even just BTX, and total
petroleum  hydrocarbons  (TPH).
Later, TPH was split into gasoline-
range organics (GRO), diesel-range
organics (DRO), and sometimes even
high-range organics (HRO). Exceed
the action levels  and you're in the
cleanup program.
    With  the  advent of risk-based
corrective action (RBCA) programs in
the early  1990s, you needed some
sort of toxicology data to be able to
generate  safe levels in  soils and
groundwater. One approach was to
use groups of chemicals and choose a
surrogate  to represent the toxicology
of the group (e.g., the method used
by the TPH Criteria Working Group,
1997). Another method was to estab-
lish a list of chemicals of concern  for
each  petroleum  product  and use
available  toxicology  data for each

                                                                               November 2004 • LUSTLine Bulletin 48
chemical to generate acceptable con-
centrations. Some states kept the list
short, and other states added long
lists of analytes for required testing.
   Around the time that the Santa
Monica,  California,  wells  were
impacted with MtBE, tank programs
began to realize that they needed to
add another analyte to the list. A few
states were already looking for MtBE
at that point, but they were few and
far between. In January  2000,  60
Minutes put the tank program in the
spotlight again with a double-length
segment devoted to MtBE. At least
we had warning that the segment
was going to air, because most states
had to scramble to create fact sheets
about the additive, field questions
from the local print and news media,
and respond to questions from resi-
dents questioning whether they had
MtBE in their drinking water.
   Two days after the  60 Minutes
presentation,  the  EPA Office  of
Underground Storage Tanks (OUST)
strongly urged the states to immedi-
ately begin monitoring and  reporting
MtBE and other fuel oxygenates at all
LUST sites (U.S. EPA, 2000). Based on
the New England Interstate Water
Pollution Control Commission's sur-
vey on state experiences with MtBE
being conducted  at approximately
that time (NEIWPCC, 2000), 42 states
were looking for MtBE in groundwa-
ter, and 29 were looking for MtBE in
soil samples. Only four or five states
were looking for any of the other oxy-
genates "most of the time."
   In another survey, based  on
responses from 27 states, over 91,000
LUST sites were closed prior to MtBE
sampling/analytical  requirements
(Sakata and Martinson, 2001).
   And what about  the other oxy-
gentate in gasoline?

  "Many within  the  petroleum
  industry  have suggested  that it
  was overemphasis on benzene in
  the 1980s and  early 1990s that
  caused them to neglect MtBE. It
  appears that we may  not  have
  learned from this oversight,  and the
  pattern maybe  repeating  itself.
  Where there is now an emphasis on
  MtBE, in many places they are not
  looking for or evaluating the poten-
  tial impact from the other fuel oxy-
              GRAY AND BROWN, 2000
How Much Is Acceptable?
Now that more states are looking for
the fuel oxygenates, one of the prob-
lems in dealing with them becomes
"How much is acceptable?" There are
no established maximum contami-
nant levels (MCLs), and little toxico-
logical data are available for any of
the fuel oxygenates, so deciding how

  Now that more states are looking for
    the fuel oxygenates, one of the
    problems in dealing with them
 becomes  "How much is acceptable?"
  There are no established maximum
 contaminant levels (MCLs), and little
  toxicological data are available for
    any of the fuel oxygenates, so
 deciding how to deal with them under
  a RBCA program can be a problem.
   Some states are waiting for EPA to
   establish an MCI, and others have
 tired of waiting and have established
        their own standards.
to deal with them under a RBCA pro-
gram can be a problem. Some states
are waiting for EPA to establish an
MCL, and others have tired of wait-
ing and have established their own
    Now that several reformulated
gas (RFC) states have banned MtBE
(including California, New York, and
Connecticut) with  the  oxygenate
mandate still in  place,  ethanol is
becoming an emerging chemical of
concern, with related issues of fate
and transport, remediation technolo-
gies, analytical methods, and UST
system compatibility.
    As  we  look  ahead  to future
changes in the composition of gaso-
line and other petroleum products,
we must also look to the past, at vari-
ous components of leaded gasoline,
ethylene dibromide (EDB  or 1,2-
Dibromoethane), 1,2-Dichloroethane
(EDC), and  tetra-ethyl lead, which
were not examined.

The RBCA Process
One of the greatest changes I've seen
happen to the LUST program is the
development and application of the
RBCA process, which involves evalu-
ating all aspects of a site and deter-
mining how much of a release can
safely be left in the ground,  rather
than remediating the  site to a one-
size-fits-all predetermined  cleanup
number.  The program  was devel-
oped in part to help  us target our
cleanup dollars to where environ-
mental risk is highest.
    For some states, where  cleanup
numbers were low or fixed for every
site, this marked a significant change
in the  way of doing  business. For
others, where a more site-specific
approach  to  setting cleanup goals
was already being used, this  repre-
sented less of a change.
    I will admit, however,  that the
concept still gives many of us major
heartburn when we see the cleanup
numbers generated using the pro-
cess. As  we  watch our soils and
groundwater being left with  "safe"
levels of chemicals, particularly when
you consider the small number of
chemicals that we are  actually look-
ing for out of the huge number of
chemicals in  the products  that are
released, we can't help but wonder...
(Ellis, 2003).

Quicker, Better
Another major change I've observed
during my tenure with the LUST pro-
gram is the development of many
tools that allow us to do quicker, bet-
ter investigations. When I  started
with the program 15 years ago, moni-
toring wells were the norm. If there
was a release, the consultant sent in a
workplan to install a few monitoring
wells (usually no more wells than the
absolute minimum needed to deter-
mine groundwater flow).
    After a few weeks of waiting to
get a driller and permits, the consul-
tant would go  out to the site and
install three wells. After developing
the wells and waiting a few weeks for
the well  to stabilize,  groundwater
samples would be collected. Then,
after waiting a few more weeks for
lab analyses, the consultant would
write a report and send it in to the
    Oops—with three wells, maybe
you've got an upgradient well, and
the other two  are kind of  cross-
                 • continued on page 4

LUSTLine Bulletin 48 • November 2004
 120 Years from page 3
gradient/downgradient. That's not
enough.  So the consultant writes
another workplan,  proposes more
wells, waits for approval, goes back
to the field, puts in more wells, waits
for the analytical. Good, we have a
downgradient well this time, but we
sure aren't at the end of the plume.
Repeat the cycle.
   With the  advent of direct-push
technologies, the consultant could
propose a dozen holes, and get the
samples collected in a day. The sec-
ond  round might then consist of
monitoring well installations, this
time in locations where they needed
to be, where good data  could be col-
lected. Sometimes direct-push  sam-
pling was accompanied by a mobile
lab that allowed decisions to be made
in the field.
   When the "diving plume" phe-
nomenon became  more  common
knowledge (see Weaver and Wilson,
2000), direct-push technologies could
be used for three-dimensional plume
characterization.  Guidance docu-
ments were produced describing the
benefits and process of expedited site
assessments (U.S. EPA, 1997), involv-
ing direct-push sampling methods
and a host of other technologies that
could assist in more rapid  and com-
plete site characterization—smarter,
better, faster, and often,  even cheaper
site assessments.

The 1998 Deadline...No More
Leaking Tanks?
As the 1998 deadline for UST owners
to close,  upgrade, or replace  their
tanks approached,  our  workload
increased drastically. Lots  of people
sputtered that the #!!%&##© govern-
ment was  making them remove a
perfectly  good tank that wasn't leak-
ing, but it was no surprise to us that a
considerable number of those tanks
had, in fact, been leaking—whether
or not inventory and tank testing had
ever given an indication of a release.
The closer to the deadline these tanks
were removed, or  in  many cases,
after the deadline,  the higher the
chances  were  that the state  was
requiring MtBE analysis at the time
of removal. Not only were a lot of
tanks coming out of the ground, but
they were triggering investigations
for a chemical for which many states
had not previously been looking and
often had no experience in remediat-
   We assumed that 1998-compliant
tank systems wouldn't leak. They
were state-of-the-art and had all the
bells and whistles. You'd know  it
right away if any product dared to
escape. We figured we'd  get our
backlog cleaned up, whittle down the
last of the oldie-but-moldy sites, and
work ourselves right out of a job.
Bzzzzz! Wrong answer.  Tank sys-
tems still leak somehow. We often
just don't know how! Or the sophisti-
cated leak-detection systems are just
too much for some people—Darn
things always buzzing, beeping, and
alarming. Must not be working right!
Turn them off!

   In the future, as the number of
 releases declines, the backlog of old
 cleanups can be reduced. I, for one,
   hope that we don't pinch pennies
   when it comes to upgrading the
     requirements for new tank
 installations. If increasing spending
  a few hundred here and a thousand
 there on a new system will prevent a
   release that can cost from tens of
   thousands to millions to clean up,
         it's worth the price.

   Somewhere  along the  line,  it
occurred  to  us  that  tanks often
weren't the source of the problem.
The  lines, with all their joints and
elbows could be a problem, sumps
(or lack of sumps) could be a prob-
lem,  and under the dispensers was a
good place to look for, and find, cont-
   Then there  are   the  miracle
releases. If a tank system isn't tight,
all of the chemicals should be escap-
ing—not just the MtBE. Alas, the con-
cept  of vapor releases has emerged.
And vapors don't just escape and
waft off into the atmosphere, they
can dissolve in soil moisture...and
end  up  in the  groundwater...and
show up in monitoring wells...and
nearby potable wells...and sometimes
the not-so-nearby potable wells.
New Initiatives on the
In October 2002, OUST rolled out its
USTfields initiative to promote the
cleanup of the approximately 200,000
abandoned tanks at brownfields with
a series of pilot  grants. The  2002
Brownfields law authorizes EPA to
give grant money to states and com-
munities  so  they  can  inventory,
assess, and clean up petroleum-cont-
aminated  brownfields.  (See http://
This money complements the OUST
USTfields initiative.
    Another of the 2002 initiatives
was a re-evaluation of UST system
design. While this is a compliance-
side initiative, it will have impacts on
the LUST side of the program down
the road, identifying additional LUST
sites  as upgrades  are  made  and,
hopefully, decreasing the occurrence
of future releases.
    In the future, as the number of
releases declines, the backlog of old
cleanups can be reduced. I, for one,
hope  that we don't pinch  pennies
when  it  comes to upgrading the
requirements for new tank  installa-
tions. If increasing spending a few
hundred here and a thousand there
on  a  new system  will prevent a
release that can cost from tens of
thousands to millions to clean up, it's
worth the price.
    "Accelerated   Cleanup"   was
another of the initiatives rolled out in
October 2002.  This initiative  was
designed to address the backlog of
139,000 tank releases that still hadn't
reached closure. It was designed to
identify the holdups in the  process.
Are the investigations not getting
underway? No RP? Recalcitrant RP?
No money? Once an investigation is
complete, is  cleanup  not getting
started? Are the technologies applied
at a site not successful, and if not,
why not?  Maybe the results of this
initiative  will  allow us to work
    Here are the figures from March
2004 (

 • 443,568 releases confirmed
 • 408,834 cleanups initiated (92%)
 • 311,125   cleanups   completed
 • 132,443 cleanups not yet com-
    pleted (31%, with 50%  of these

                                                                            November 2004 • LUSTLine Bulletin 48
   involving groundwater contami-
 • Completed cleanups reported for
   2003 met EPA's annual national
   cleanup goal of approximately
   18,000 and reversed a three-year
   downward trend in the number
   of cleanups completed.

   Wow! Five  hundred  twenty-
three of those confirmed releases are
mine—0.1 percent!  Four hundred
forty-one of the cleanups  completed
are mine—0.1 percent. Eighty-two of
the  cleanups not completed  are
mine—0.06 percent. No wonder I'm
tired! I don't think the answer lies in
setting numerical quotas, though.
Subliminal message—send money,
lighten project load, stop leaks!
    Setting numerical quotas for each
state ignores many of the differences
between state programs. Some states
are required by law to remediate to
MCLs—no MCL, no closure. In some
states, all cleanups are paid for by the
state cleanup fund, so you have less
of a fight to get the cleanup initiated.
In some states, each project officer
may have as many as 300 LUST pro-
jects to handle, and it makes a consid-
erable difference how those projects
are funded, contracted, and so on, as
to how that workload might compare
with that of a LUST project officer in
another state.
    Try this calculation: take the
number of days in the year, subtract
weekends, holidays, vacation, and a
few sick days and divide that by the
average number  of projects that an
average project officer might have.
That's how many days per year that
you can average  for each project (if
you don't go to any training and
don't attend and meetings and  don't
spend time on planning or program
development). If you've got a few big
LUST projects that suck up a bunch
of your time, reduce the amount of
time accordingly that you can devote
to any of the lower-priority projects.

               • continued on page 17
 Director, U.S. EPA Office of Underground Storage Tanks
 As We Begin Our Third Decade, Strong Action
 and Creative Solutions  Are Essential
      This is a special year for those of us working in the
      underground storage tank program. In November
      we will celebrate the 20th anniversary of the pro-
 gram—and we have a lot to celebrate. Just this past year,
 we surpassed 300,000 cleanups, we continue to cut the
 number of new leaks—from a high of almost 67,000
 releases in 1990 to about 10,000 last year—and we are
 beginning to make some real progress cleaning up aban-
 doned petroleum brownfields sites. As former U.S. Sena-
 tor David Durenberger said about our program, "With
 the right balance between technology, industry, federal,
 state, private, and public forces, you can get a lot done."
 We have struck the right balance, and we have gotten a
 lot done.
    But as we celebrate 20 years of accomplishments, our
 work is not finished.  We still have over 130,000 petro-
 leum leaks not yet cleaned u,p and only six in ten gas sta-
 tions are in full operational compliance. Far too often we
 hear stories about leak detection alarms that are turned
 off or equipment that is installed wrong, and we now
 have evidence about new or upgraded leaking tanks and
 pipes that should not be leaking. To make matters worse,
 we are facing these challenges at a time of tight budgets,
 highly stressed state cleanup funds, and growing con-
 cerns from citizens demanding faster cleanups.
    These challenges call for strong action and creative
 solutions. Here's what I suggest:

  • Prevent releases in the first place. With cleanup bud-
    gets so tight, release prevention is critical. By inte-
    grating compliance and prevention into the design
    and execution of  our cleanup funds we can create
    incentives  for tank owners to prevent releases. By
    better educating tank operators and better training
    inspectors  we can improve compliance. The  good
    news is that we are close to launching a new Web-
    based training course for EPA and state inspectors.
                     Once this is up and run-
                     ning, inspectors can take
                     the training 24/7 at their
                     own desks. As for tank
                     operators,  we just  fin-
                     ished writing an easy-
                     to-use regulatory check-
                     list patterned after EPA's
                     successful Environmental Results Program.

                  • Improve program integration. Fortunately, we just initi-
                     ated a new partnership to share data with our col-
                     leagues in the drinking water program. Through this
                     partnership we have learned that some states rank
                     USTs as one of the top threats to their designated
                     source water areas. This simple but important data-
                     sharing partnership will help us make the best use of
                     our resources and increase public health protection.

                  • Develop  new  tools and technologies to  streamline
                     Cleanups. This can be done through the use of multi-
                     site agreements, pump-and-treat optimization, and
                     systematic project planning and real-time measure-
                     ment—commonly known as "Triad." We also need
                     better methods to detect vapor releases from tanks
                     and cost-effective ways to make sure tanks are both
                     liquid and vapor tight.

                     This November, when we pause to celebrate our pro-
                 gram's 20th anniversary, we should take pride in the
                 tremendous progress that we have made. By working
                 together, we have successfully cleaned up more than
                 two-thirds of all known leaks and prevented thousands
                 of new leaks. As we begin the third decade of our pro-
                 gram, we face even tougher challenges. But as before, by
                 continuing to work together we will meet whatever the
                 future brings. •

LUSTLine Bulletin 48 • November 2004
                                        OUST UPDATE
 New Model Environmental
 Results Program Workbook
 for USTs Unveiled
 The U.S. EPA Office of Underground
 Storage Tanks (OUST) has developed
 a Model Underground Storage Tank
 Environmental  Results  Program
 Workbooks  to help state UST pro-
 grams and  state  funds improve
 owner and operator compliance with
 UST regulations. States may need to
 modify the model  workbook  to
 reflect their own state laws. States
 may then request or require tank
 owners and operators to follow the
 final,  state-specific environmental
 results program (ERP)  workbook,
 which can help owners remain in or
 achieve  compliance  with  UST
     ERP is an innovative program
 that can improve the environmental
 performance of a large  number of
 small sources within a state's regula-
 tory system. Some states have suc-
 cessfully  used  ERP to improve
 environmental performance  in other
 small business sectors, such as auto
 repair, dry cleaning, printing, and
 photo processing.  ERP  consists of
 three related components—inspec-
 tion and performance measurements,
 self-certification,  and  compliance
 assistance—which work together to
 produce an  integrated system that
 holds facility owners accountable for
 their environmental UST regulations.
     The primary audience  for  the
 workbook is UST owners and opera-
 tors  who  either volunteer or  are
 required to use the workbook to
 determine whether or not their facili-
 ties comply with UST requirements.
 The  164-page workbook contains
 general information  about  ERP,
 instructions on how to use the work-
 book, regulatory requirements, best
 management practices, and  compli-
 ance checklists for USTs and draft
 forms and worksheets in the appen-
 dices. The workbook is available only
 on  the   OUST  Web   site   at (EPA-
 510-R-04-003, June 2004). For more
 information, contact Paul  Miller
 (703) 603-7165.
EPA Report on Technologies
to Remediate MtBE and
Other Fuel Oxygenates
Over the past several years U.S. EPA
has been  documenting experience
with technologies to remediate fuel
oxygenates and has  recently pub-
lished Technologies for Treating MtBE
and Other Fuel Oxygenates. The report
is an overview of the treatment tech-
nologies used to remediate ground-
water,   soil,  and  drinking  water
contaminated with MtBE and other
fuel oxygenates. It summarizes avail-
able cost and performance informa-
tion for eight treatment technologies,
provides examples of where they
have been used, and contains addi-
tional sources of information. .  The
technologies range from exsitu drink-
ing water treatment methods to in
situ techniques.
    The report was prepared by the
Office of Superfund Remediation and
Technology Innovation (OSRTI) and
is available online at http://www.clu- Much of
the data in the report was derived
from the MtBE Treatment Profiles
database   (
/mtbe), which provides project man-
agers with examples of the  use of
technologies at specific sites.  OUST
and  OSRTI  are sending  reference
copies to  regional  and state LUST
programs.  EPA is not recommending
the use of any specific product or ser-
vice mentioned in the document. For
more information, contact  Linda
Fiedler (703) 603-7194.

New Report on UST
Dispenser Releases in
South Carolina
U.S. EPA has produced a new report,
Frequency  and Extent of  Dispenser
Releases  at Underground Storage Tank
Facilities in  South  Carolina,  which
describes the results of information
collected and analyzed from UST clo-
sure and assessment reports at sites
in  South  Carolina.  The  report
describes the background, purpose,
methodology used, quality assurance
and  quality control  procedures
applied, results of the study, and con-
clusions. It includes supporting infor-
mation in the appendices. EPA devel-
oped this report as part of its ongoing
evaluation of UST systems and to
contribute to the UST community's
understanding of dispenser releases.
    "This study reaffirms the threat
posed by releases from dispensers,"
says OUST Director Cliff Rothen-
stein. "Nearly half  of all facilities
reviewed as part of this study had
contamination under one or more
dispensers, and nearly one quarter
had contamination exceeding South
Carolina's risk-based screening lev-
els. With 256,000 facilities nation-
wide—only  half  of which  have
containment   under   their   dis-
pensers—the national implications
are significant."
    Rothenstein  adds  that  while
increased use of dispenser contain-
ment should help reduce the future
risk posed by dispenser releases, vig-
ilance on the part of inspectors, own-
ers and  operators, and  service
personnel is critical to minimize or at
least contain future dispenser leaks.
    Copies of the report (EPA-510-R-
04-004, September 2004) are available
through  OUST's   Web   site  at   or  by  calling
NSCEP, OUST's publications ware-
house at (800) 490-9198.

New Guide on Evaluating
Alternative Cleanup
Technologies at UST Sites
U.S. EPA has updated its manual,
How to Evaluate Alternative Cleanup
Technologies for Underground Storage
Tank Sites: A  Guide for Corrective
Action Plan Reviewers, for federal and
state UST professionals.  The  one
revised and two new chapters in the
manual  discuss monitored natural
attenuation (Chapter 9), enhanced
aerobic bioremediation (Chapter 12),
and chemical oxidation (Chapter 13)
at UST corrective action sites.  The
original manual was released in 1994
and then revised in May 1995.
    A limited number of copies of the
manual at no cost (EPA-510-R-04-002,
May 2004) are available by calling
NSCEP at (800) 490-9198. Copies can
be downloaded at OUST's Web site
at •

                                                                            November 2004 • LUSTLine Bulletin 48
Age-Dating Releases  at LUST  Sites:  Part  1.

Lead  [Isotopic] Fingerprints

by Richard W. Hurst

     "The significant problems we face cannot be solved at the same level of thinking
     Sometimes we plan our research. Sometimes a course of research comes knocking at our door. My story
     begins circa 1989, when I began to receive calls, predominantly from attorneys, concerning my knowledge
     and/or ability to age-date releases of gasoline into the environment. I was recognized as a forensic geo-
chemist, performing environmental isotope and geochemical research as a professor of geology I geochemistry at
California State University, Los Angeles, and as a consultant for the petroleum industry and environmental
    Little did I know that those calls would lead me into a project that would envelop a substantial chunk of my
research efforts over the next 15 years. The contribution has been well worth the time, both professionally and per-
sonally, having taken me full cycle from age-dating the oldest rocks in the world during my doctoral days to dat-
ing the youngest events, those associated with 20th-century releases of refined petroleum hydrocarbons.
LUSTing for an Answer
Given that the era of leaded gasoline
in the U.S. has passed, analyses of
samples for lead at LUST  sites are
performed less frequently. However,
lead (Pb) and its four naturally occur-
ring isotopes are persistent in the
environment, as none are degraded
by biogeochemical processes (Faure,
1986). As a result, lead isotope ratios
(e.g., 206Pb/207Pb, 208Pb/20*Pb) can
provide valuable insights, serving as
"fingerprints" of historic  gasoline
releases at LUST sites  and offering
answers to questions such as:
  •  What  year   did  the  gasoline
    release occur?
  •  How many releases occurred and
    did they commingle?
  •  What is the source (or sources) of
    the leaded or unleaded release?
  •  How should the liability for site
    remediation and cost recovery be
    apportioned among potentially
    responsible parties (PRPs)?
    The ability to  age-date a gasoline
release is not trivial;  many have tried.
My contribution to this forensic effort
has been to develop a  model based
on calibrated temporal variations or
changes in the lead  isotope ratios of
leaded gasoline.  Called  the ALAS
Model (Anthropogenic Lead Archaeo-
Stratigraphy; Hurst  et  al., 2001;
Hurst, 2002a, 2002b),  since about
1993 it has been applied at about 100
LUST sites in the U.S. as a tool to
assist regulatory agencies and PRPs
(along with their  representatives)
answer the questions posed above.
    In this first of a two-part series in
LUSTLine, I will review lead isotopes,
the details of the ALAS Model, and
the age resolution possible. Given
that many readers may be treading
on unfamiliar turf, Part 1 provides
the technical foundation needed. In
Part 2, I will present representative
applications of the ALAS Model at
LUST  sites  via case  studies that
involved cost recovery and site reme-
diation. In addition, the case studies
will demonstrate how lead isotopes
are used to: (a) differentiate natural
from  LUST-derived lead; and (b)
model the relative contributions from
commingled releases.
    Used  properly,   with  good
sampling strategy and sampling pro-
tocols   (i.e.,  a  sound  scientific
approach), lead isotope ratios pro-
vide a viable means of: (a) estimating
the year leaded gasoline was released
into the environment (Kaplan, 2003;
Schmidt, personal communication);
and (b) fingerprinting sources  of
leaded/unleaded gasoline releases as
well as their dissolved-phase con-
stituents (e.g., BTEX, MtBE).

CSI Lead FAQs—What Clues
Does Lead Leave Behind?
As  stated above, the persistence of
lead in the environment is well estab-
lished, and hence, despite the fact
that gasoline is no longer leaded, the
lead from  past gasoline releases
remains adsorbed onto soil minerals
as a record of that release long after
the gasoline  organic constituents
have degraded.
    From the perspective of anyone
charged with the decision to close a
site and/or assess liability, lead is
gone from gasoline; however, from
my perspective,  lead  from past
releases is retained at LUST  sites—in
soils, free product, and groundwater;
hence, it is important. Despite the
clues  left by lead, as with  any CSI
forensic investigation, representative
samples should be collected for analy-
sis prior to site remediation following
appropriate sampling protocols. Let's
examine some issues/questions that
arise  regarding  sampling/analysis
and their resolution.
• Soil/groundwater lead concentrations
do not exceed the  regulatory threshold
value, hence they are attributable solely
to the natural background.
Many believe that if lead concentra-
tions in a soil/ground water are low,
no anthropogenic lead is  present.
This cannot be resolved using con-
centration analyses  alone, but by
incorporating lead isotopes  it is pos-
sible to fingerprint both natural and
anthropogenic lead, even at  low con-
centrations (e.g., tens of ppb), well
below those of regulatory-mandated
threshold values—this will be dis-
cussed in Part 2 in more detail.

• Should I add a preservative to
samples, and what about the potential
for removing lead from particulates in
groundwater when samples are
It is imperative  that groundwater
samples never lie acidified because of
                • continued on page 8

LUSTLine Bulletin 48 • November 2004
• Isotopic Fingerprints from page 7

the potential to extract lead from sus-
pended/colloidal participates whose
lead  concentrations  and  isotope
ratios reflect the characteristics of the
aquifer material, not the contami-
nant! This will lead to artificially high
dissolved lead concentrations  that
will be attributed, incorrectly, to a
gasoline release (Hurst, 2000; Land-
meyer et al, 2003).
    Because any preservative may
contain  lead, no  sample  matrix
should be preserved other than by
chilling to preserve organics—lead
does not degrade, hence it need not
be preserved. Ask yourself, would
we have a global lead pollution prob-
lem if lead degraded?

• How is anthropogenic lead removed
from soil without extracting background
lead from the soil matrix (minerals)?
Sequential chemical extraction proto-
cols have been developed to strip the
anthropogenic lead component ad-
sorbed on the surface of soil minerals
without removing lead bonded in
soil  minerals (Hurst,  2000). This
approach is very effective when it
comes to deciphering the number of
releases at LUST sites. At this time, I
have collaborated with and trained
researchers at MIT who perform the
required extractions per my instruc-
tions following my evaluation of site-
specific conditions and client needs.

• Can commingling of petroleum
hydrocarbon plumes homogenize lead
isotope ratios, compromising their
On the contrary, commingling of
plumes can  be identified and mod-
eled using lead isotope/concentra-
tion data from sequential chemical
extractions in order to assess the rela-
tive contributions from each release.

ALAS Model: Historic  U.S.
Gasoline Lead Isotopic
Temporal Variations
Ng and Patterson  (1982) must be
credited with identifying the rapid,
temporal  increases in  206Pb/207Pb
ratios of the anthropogenic lead com-
ponent of sediment in southern Cali-
fornia and attributing the change to
our increased reliance on Mississippi
Valley Type (MVT)  lead to produce
alkyllead additives.
    Briefly, MVT lead ores have very
high, or radiogenic, 206Pb/207Pb ratios
(~1.3) relative to other ores whose
ratios range from  about 1.0 to 1.2.
Furthermore, Ng and Patterson pro-
posed, correctly, that the similarities
between the 206Pb/207Pb ratios of the
anthropogenic  lead component in
sediments and those of contempora-
neous gasoline-derived aerosols from
1965 to 1975 indicated gasoline com-
bustion, a  major source  of anthro-
pogenic  lead  both  locally   and
    Their work, however, focused on
global lead pollution, not the devel-
opment of a chronometer to age-date
gasoline releases. Realizing the need
for improved accuracy in estimating
the age  of gasoline  releases,  my
approach  was  to use  the   Ng-
Patterson data as the prototype cali-
bration curve and build upon it. The
next leg of this journey was to:
  •  evaluate whether the temporal
    increases observed in gasoline
    lead isotopic ratios could be cali-

  •  determine the age resolution of
    the hypothetical technique

  •  assess its geographic  applicabil-

    I started to acquire samples to
calibrate what  would   eventually
become  the  ALAS  Model (e.g.,
archived leaded gasoline, free-prod-
uct-impacted soils from documented
releases). In short, this was a tedious
task, but as a result of 10  to 12 years
of work, the current ALAS Model cal-
ibration includes more than 125 free
product/soil lead isotope analyses of
documented    gasoline    releases
throughout the U.S. (i.e.,  California,
Illinois, Florida, New Jersey, Arizona,
Massachusetts, Ohio, Washington,
Texas, New York, Oregon, and Penn-
sylvania). The ALAS Model is shown
in Figure 1. (At the scale of the figure,
only about 35 of the 125  individual
data points can be resolved.)
    As I am my own toughest critic, I
decided to further refine  and evalu-
ate the model. How?  The ALAS
Model remains the only gasoline age-
dating model for which historic data
are available to, so to speak, model
the model. First, using annual U.S.
Bureau of Mines lead production fig-
ures (1920-1992), I calculated the con-
tribution of lead from each state and
foreign source relative to total U.S.
lead production. Second, I integrated
the results with published ore lead
isotopic  ratios  for  each source to
calculate annual average 206Pb/207Pb
ratios of U.S. industrial lead (Hurst,
2002b). These calculations and data
acquisition required about 10 months.
    What was the result? The correla-
tion between the calculated ratios
with those of ALAS Model calibra-
tion samples is statistically significant
(R2 = 0.95; Figure 1), indicating that
the ALAS Model could, in fact, be
modeled. It also suggested that major
manufacturers  of tetra-ethyl lead
(TEL) (e.g., Ethyl and DuPont) pur-
chased lead from the average U.S.
lead market.
    This  result provided an answer
to a valid question posed by detrac-
tors of the ALAS Model that alkyl-
leads,   may,   on   occasion,   be
manufactured entirely from a ship-
ment of, let's say, Australian lead that
has a very different lead isotopic sig-
nature. Furthermore, historical data
acquired by Robert (1984)  indicate
that Ethyl and DuPont collaborated
on TEL and other alkyllead produc-
tion, hence they purchased lead from
the same U.S. lead market.
    Additional  support came in the
form  of  correlations between the
ALAS Model and independent analy-
ses of atmospheric aerosol lead iso-
tope ratios (Figure 2), which are: (a)
very significant when leaded gaso-
line combustion was a major source
of lead in the atmosphere between
1962 and 1985  (R2 = 0.87); and  (b)
poor, after 1985, as alkyllead concen-
trations in gasoline decreased from
1.1 to 0.1 gm/gal (R2 = 0.003).
    The   significant   correlation
between  the  ALAS Model and
aerosol lead isotope ratios was one of
the first  lines of evidence  that the
model had  potential applicability
throughout the U.S., rather than just
California, where it was  initially
developed. But why should lead iso-
tope ratios of the ALAS Model and
aerosols  from gasoline combustion
be  in such accord throughout the
    In  1933, the Ethyl Corporation
capitalized on its virtual monopoly of
TEL production and began market-
ing TEL throughout the U.S. (Robert,
1984). Despite the fact that there were
numerous petroleum  companies,

                                                                                  November 2004 • LUSTLine Bulletin 48
 FIGURE 1. ALAS Model calibration curve. 37 of ~ 125 calibration samples can be resolved at the
 scale of the figure; the line depicts the ALAS Model as calculated from U.S. Bureau of Mines
 annual lead production figures and known lead isotope ratios of lead ores mined globally.
                  — ALAS (Calculated)  . ALAS (Calibration)  A ALAS (pre-1955 Calibration) |
 FIGURE 2. ALAS Model versus lead isotope ratios of atmospheric aerosols. Note the distinct
 similarity between the 206Pb/207Pb ratios of the ALAS Model and aerosols prior to 1985, when
 the dominant source of atmospheric lead was leaded gasoline combustion.




    g  1.200
    °  1.180-


                   |	ALAS (Calculated) • Patterson etal. • Rosman » Chow  A Sturges/Barrie g GGC |
there was only one Ethyl Corporation
from which gasoline refiners could
purchase TEL, and Ethyl bought lead
from the average U.S. lead market,
which focused on MVT lead sources.
    Economically, Ethyl realized that
it made no sense to mine lead and
either store it for long periods of time
or transport it great distances.  As
realized by medieval alchemists, lead
cannot be transformed into gold—in
its heyday, about 1950 to 2000, lead
commanded a maximum price of
about 50 cents per pound. For this
reason, Ethyl Corporation sited the
majority of its TEL production facili-
ties  (Louisiana,  South   Carolina,
Texas) proximal to sources of MVT
ore (Robert, 1984).
    Lastly, as observed in Figure 1,
there are two ways lead isotope ratios
are  represented:  as   the  "raw'
206Pb/207Pb ratio  and as a "delta"
notation, A206Pb, relative to a lead iso-
topic reference standard  (i.e.,  like
light-stable isotope ratios of carbon
are reported). I will not discuss the
details  of reporting  lead isotope
results in the delta notation; suffice it
to say it is used in litigation  where
small differences  between isotopic
ratios often confuse nontechnical folks
who more clearly understand com-
parisons of numbers like +5.2 or - 3.7.
Why Does the ALAS Curve
Look Like It Does?
Let's look deeper  into  the control
imparted by the use of radiogenic
MVT ores on the ALAS Model before
versus after 1960. We will also get
some sense of how rapidly lead went
from the mine to the TEL market.
    Prior  to  1960,  the 206Pb/207Pb
ratios of gasoline lead fluctuated but
remained low, about 1.15 to 1.175;
observed fluctuations are dependent
on sources of lead, and MVT lead
contributed about  30 to 50 percent
(average  42  percent)  to annual
domestic U.S. lead  production prior
to 1960. During the war years (World
War II, Korean War), 1937 to  1954,
lead  was  used,   in   part,  for
military/defense purposes.
    In 1940, the  proportion of less
radiogenic foreign and domestic ore
increased (25 to  50 percent of U.S.
total lead production) while  MVT
sources declined (U.S. Bureau  of
Mines Yearbooks,  1939-1941). The
result  was  immediate—an anom-
alously low 206Pb/207Pb ratio in
1940 (~  1.155) relative to other years.
Low 206Pb/207Pb ratios during the
Korean War years also reflect a drop
in domestic  MVT ore  production
and/or its use by the military.
    The post-1960 interval was ini-
tially marked by a decrease in ALAS
Model 206Pb/2"7Pb  ratios to  about
1.15, followed by the steady, rapid
increase to values  of about 1.23  by
1990. The increased reliance on MVT
lead, whose proportion of total U.S.
lead increases  systematically  after
about 1965 to greater than 85 percent
by the 1980s, contributes to the dra-
matic increase in 206Pb/207Pb ratios
observed in the ALAS Model during
this time interval.
    The minimum  in 1962 is linked
directly to a workers strike at the
largest MVT lead mine in Missouri.
What  is  so  important  here,  as
observed in 1940, is the "from mine
to market" factor—in 1962, MVT ore
production ceased for months but
was replaced by less radiogenic lead
from Idaho (U.S. Bureau  of Mines
Yearbook, 1962).
    As observed in 1940 and again in
1962, the ALAS Model 206Pb/207Pb
ratio decreases immediately (Figure
1). These observations indicate just
how rapidly lead went from the mine

                 • continued on page 10

LUSTLine Bulletin 48 • November 2004
• Isotopic Fingerprints from page 9

to TEL production and further sup-
port my contention that large quanti-
ties of lead from sources that were
not representative of the average U.S.
market did not occur because they
would have  been recorded in the
ALAS Model.

How Precise and Accurate is
the ALAS Model?
When applied properly, by defining
a site-dependent sampling strategy,
integrating lead-organic geochemical
analyses of a statistically significant
suite  of  samples, and quantifying
commingling   among    multiple
releases, ALAS Model  ages have
proven reliable  and  accurate—as
long as you do the science.
   The analytical uncertainty of the
model is a function of the steepness
(i.e., slope) of the ALAS Model cali-
bration curve (Figure 1). Where the
ALAS Model uncertainty is greater,
between about 1965 and 1982, an ana-
lytical uncertainty of ± 1 year in the
model age of a release is attainable.
The model age uncertainty increases
to ± 2 years for releases that occurred
post-1982. For releases that occurred
prior  to the early 1960s, where the
ALAS Model is much "flatter," the
ALAS Model age resolution increases
to ten-year intervals. Furthermore, the
fluctuations observed in the ALAS
Model curve prior to about 1970 can
produce more than one unique ALAS
Model age. (See Figure 1.)
   ALAS  Model ages throughout
the U.S.  have been quite accurate,
typically  agreeing  to within two
years  (Figure 3) with the "suspected"
age of a release. The "suspected" age
of a release means my  client pro-
vided a best estimate of the age of the
release, based on  inventory/Haz-
Mat/fire department  records. It is
important  to recognize that ALAS
Model ages have always been deter-
mined independently  with neither prior
knowledge of the "suspected" age or year
of a release at a particular site nor the
age(s) that would most benefit a client's
exposure in litigation involving hydro-
carbon contamination at a site.

What Have We Learned
So Far?
The ALAS Model is based on system-
atic increases observed in lead iso-

 FIGURE 3. ALAS model ages versus the age of gasoline releases throughout the U.S.
 The excellent correlation between the model and suspected age of releases from actual site
 remediation demonstrates the utility and accuracy of the ALAS Model.
   o>  1965
   £  1955

                                 Age of Release
                 |»CA nCA AFL  XIL * IN • MA +MD A MO DNJ »OR .PA . TX X VA |
tope ratios of gasolines caused by
shifts in sources of lead ores used by
the U.S. lead  industry,  including
manufacturers of alkylleads, to more
radiogenic Mississippi Valley Type
deposits. Acquisition of high-quality
samples  of known age and  high-
precision lead isotopic analyses over
about 14 years has resulted in a cali-
bration curve  whose  model age
uncertainties range from ± one to two
years  for  gasoline  releases  that
occurred between 1960 and 1990, a
major  era in the history of leaded
gasoline usage.
    Numerous site-specific investiga-
tions involving free-product releases
throughout the U.S.  exemplify the
utility  and accuracy of the ALAS
Model  as a tool in forensic investiga-
tions in which estimates of the age
and  identification  of  sources  of
leaded  gasoline  releases  are  an
important issue. Part 2 of this series
will provide the reader with selected
representative applications  of the
model to site-specific investigations
in which hydrocarbon remediation,
cost  recovery, and apportioning of
liability  were  the  predominant
issue(s). •

 Richard W. Hurst, Ph.D., is the Presi-
  dent of Hurst & Associates, Inc. and
  has been a Professor of Geology/Geo-
   chemistry since 1978 at California
 State University, Los Angeles. He can
 be reached at (805) 492-7764 or Alas- Check out his Web site
  A  Primer on  Lead Isotopes
  There are four naturally occurring, stable isotopes of lead (Pb), three of which
  are radiogenic (i.e., their abundances increase over time due to the radioactive
  decay of uranium, U, or thorium, Th). The Pb isotopes produced (radioactive
  parent with half-life, t1/2, in billions of years or Ga; Faure, 1986) are: 208Pb
  (232Th, t1/2 = 14.01 Ga); 207Pb (235U, t1/2 = 0.7038 Ga); and 206Pb (238U, t1/2 =
  4.468 Ga). The fourth Pb isotope, 204Pb, is not radiogenic, having no radioactive
  parent nuclide. By convention, either 204Pb or 206Pb is used as a reference iso-
  tope; analytical results are  reported as Pb isotope ratios (e.g., 206Pb/204Pb,
  206Pb/207Pb). Over earth history, Pb isotope  ratios have increased by 30 to 100
  percent or more (Stacey and Kramers, 1975).

                                                                                            November 2004 • LUSTLine Bulks
Doe, B.R., 1970, Lead Isotopes, Springer-Verlag, 137 pp.
Faure, G.R., 1986, Principles of Isotope Geology, Wiley &
 Sons, 589 pp.
Hurst, R.W., 2000, Applications of Anthropogenic
 Lead ArchaeoStratigraphy (ALAS Model) to hydro-
 carbon remediation, Jounal: Environvironmental
 Forensics, Vol. 1, pp. 11-23.
Hurst, R.W., D.  Barren, M. Washington, and S.A.
 Bowring, 2001, Lead Isotopes as Age Sensitive,
 Genetic Markers in Hydrocarbons: 1. Co-Partition-
 ing of Lead with MTBE into Water and Implications
 for MTBE-Source Correlations, Environmental Geo-
 science, Vol. 8, pp. 242-250.
Hurst, R.W., 2002a, Lead Isotopes as Age Sensitive,
 Genetic Markers in Hydrocarbons: 2. Kerogens,
 Crude Oils, and Unleaded Gasoline, Environmental
 Geoscience, Vol. 9, pp. 1-7.
Hurst, R.W., 2002b, Lead Isotopes as Age Sensitive,
 Genetic Markers in Hydrocarbons: 3. Leaded Gaso-
 line, 1923-1990, Environmental Geoscience, Vol.  9, pp.
Hurst, R.W. and Schmidt, G.W., In press, Age Signifi-
 cance of nC17/Pr Ratios in Forensic Investigations
 of Refined Product and Crude Oil Releases, Envi-
 ronmental Geoscience,
Kaplan, I.R., 2003, Age dating of organic environmen-
 tal residues, Jounal: Environvironmental Forensics,
 Vol. 4, pp. 95-141.
Landmeyer, J.E., P.M. Bradley, and T.D.Bullen, 2003,
 Stable lead isotopes reveal a natural source of high
 lead concentrations to gasoline-contaminated
 groundwater, Environmental Geology, Vol. 45, pp.
Ng, A. and C.C. Patterson, 1982, Changes of lead and
 barium with time in California off-shore basin sedi-
 ments, Geochimica et Cosmodnmica Ada, Vol. 46, pp.
                                          Lead  Isotopic Ratios  in  Ores
                                          The major source of Pb for gasoline additives, sulfide ore (e.g., galena, PbS),
                                          contains -865,000 ppm Pb but virtually no radioactive parent nuclides, U or Th.
                                          Hence, once a galena forms,  its lead isotope ratios are "frozen in time"—they
                                          do not change. Ores used to  produce alkylleads (TEL) include imported (i.e.,
                                          Australia, Canada, Chile, Mexico) and domestic sources (i.e., ID, UT, CO, MO
                                          region; U.S. Bureau of Mines Yearbooks, 1956-1989).

                                          The 206Pb/207Pb ratios of these ores are: ~1.0-1.1 (Australia, Canada, CO, ID);
                                          -1.20 (Chile, Mexico,  UT); and -1.32 (MO; Doe, 1970). The significance of the
                                          MO region ores, with regard to leaded gasoline, centers on the systematic,
                                          increased reliance of the U.S. lead industry, including Ethyl Corporation, on
                                          radiogenic  MO region lead caused gasoline lead isotope ratios to increase sys-
                                          tematically; calibration of this change would lead to the development of the
                                          ALAS Model (Hurst, 2000, 2002a, 2002b).B
                                        Robert, J.C., 1984, Ethyl: A history of the corporation and
                                         the people who made it, University of Virginia Press,
                                         448 pp.
                                        Rosman, K.J.R., W. Chisholm, C.F. Boutron, J.P.Can-
                                         delone, and S.Hong, 1994, sotopic evidence to
                                         account for changes in the concentration of Green-
                                         land snow between 1960 and 1988, Geochimica et
                                         Cosmochimica Acta, Vol. 58, pp. 3265-3270.
                                        Shirahata, H., R.W. Elias, and C.C. Patterson, 1980,
                                         Chronological variations in concentrations and iso-
                                         topic compositions of anthropogenic atmospheric
                                         lead in sediments of a remote alpine pond, Geochim-
                                         ica et Cosmochimica Acta, Vol. 44, pp. 149-162.
Stacey, J.S. and J.D. Kramers, 1975, Approximation of
 terrestrial lead isotope evolution by a two-stage
 model, Earth and Planetary Science Letter, Vol. 26,
 pp. 207-221.
Sturges, W.T. and L.A. Barrie, 1987, Lead 206/207
 isotope ratios in the atmosphere of North America
 as tracers of US and Canadian emissions, Nature,
 Vol. 329, pp. 144- 146.
U.S. Bureau of Mines, 1920-1989, Mineral Yearbook.
 :•"**"**":*!"   SN
                                                        MOM t\K
   Lightning Strike Causes Underground  Storage  Tank  Explosion
                                                                                  mately 10 feet into the air, accompanied
                                                                                  by a loud boom and heavy, black smoke.
                                                                                  One of the 18" x 18" steel access covers
                                                                                  was blown approximately 125 feet into
                                                                                  the air and landed 70 feet from the UST.
On June 8,2004,
at about 4:00 in
the afternoon,
lightning struck
an underground
storage tank in
South Carolina.
The resulting
spark ignited
vapors in the
tank, resulting  in
a large explosion
and complete
destruction of the
tank. The tank
was a 10,000-gallon fiberglass tank that had previously
contained gasoline. It had been empty since August 2002
and met the standard for temporarily out-of-service. As the
tank was owned by a large public utility, an in-depth analy-
sis of the event was conducted. The owner determined that
a -10,000 amp. (-1 Oka) lightning bolt  struck the vent line. A
15' x 30' section of concrete and backfill was lifted approxi-
      Ifyou have any UST/LUST-related snapshots from the field that you would like to share with our readers, please send them to Ellen Frye c/o NEIWPCC.

LUSTLine Bulletin 48 • November 2004
How to Collect Reliable Soil-Gas Data  for Risk-Based
Applications—Specifically Vapor Intrusion
Part  3  - Answers  to Frequently
Asked  Questions
by Blayne Hartman

     Since I wrote Parts 1 and 2 in July 2002 and October 2003 (LUSTLines #42 and #44), vapor intrusion has continued to be a
     "box-office blockbuster" throughout the environmental remediation community. I have provided vapor-intrusion training to
     no fewer than 12 states, several U.S. EPA regions, and the Department of Defense. Others, including U.S. EPA staff and the
American Petroleum Institute (API), are providing training at conferences and to interested parties. Groups such as EPA's Office of
Solid Waste and Emergency Response and the Office of Underground Storage Tanks, ITRC, and API have formed vapor-intrusion
technical workgroups. Many states have written soil-gas policy/guidance, promulgated regulations (e.g., CT, LA), prepared draft
documents (i.e., NJ, MI), or are presently contemplating preparing guidance (i.e., WA, AZ). Everyday, I receive phone and e-mail
inquiries on a variety of topics, including soil-gas protocols, analytical methods, and sampling strategies. With all this interest, I fig-
ure it's time for Part 3 in this series: Answers to Frequently Asked Questions. The following questions are accompanied by answers,
as I see them, that I hope will be helpful.
 • What is the primary reason that soil-
 gas sampling for vapor intrusion differs
 from soil-gas sampling for typical site
 The difference is in how low a con-
 centration you have to measure. For
 site-assessment applications, we typi-
 cally worry about contaminant con-
 centrations  above  1  ug/L.  For
 vapor-intrusion  applications, we
 measure down to levels as low as 1
 ug/m3, fully 1,000 to 10,000 times
 lower. This means that we need to be
 much more careful in how we collect
 and analyze samples. Field and ana-
 lytical techniques that are suitable for
 higher concentrations are often not
 suitable for these ultra-low concen-
 trations. Small contaminant blanks
 from equipment, fingers,  clothing,
 the working surface (e.g., the tailgate
 of your pick-up), even the ambient
 air can be enough to fail acceptable
 risk levels.

 • Why do you say that vapor units are
 the most common (and very significant)
 error in vapor-intrusion assessments?
 In the vapor-intrusion world, labs
 and regulations employ a vast array
 of units, including most commonly
 ppmv, ppbv, ug/L, ug/m3, mg/m3,
 and %. It's enough to drive a geolo-
 gist and risk  assessor mad.  Even
 the  engineers are having trouble
 (although they will never admit it).
    For water samples, a ppb  is
 equivalent to an  ug/L. For vapor, a
 ppbv is not equivalent to a ug/L.
Because the vast majority of us in this
field (e.g., regulators, consultants,
project managers) are used to dealing
with groundwater, it is very easy to
carry over this equivalency to vapor
samples.  Undoubtedly, this is the
most common error that I see being
made by practitioners in the vapor-
intrusion field. And it's huge! The
reason? For  benzene, one  ug/L is
equal to -300 ppbv; for TCE, -180
ppbv. So, we're talking greater than
two orders of magnitude error if the
units are inadvertently thought to be
   This  confusion  about  units
occurs most commonly in the follow-
ing situations:
 • When vapor-risk models, such as
   EPA's Johnson-Ettinger model
   spreadsheets,  are used. If you
   inadvertently flip the units, you'll
   start off two orders of magnitude
   too high or too low. Compare the
   magnitude of this error to the
   sensitivity of some of the other
   common J-E model parameters
   from default values. Porosity: fac-
   tor of 5; Qsoil: factor of 3; Ventila-
   tion rate:  factor of 10. The point is
   this error is much greater than all
   of the others combined.

 • Calculating soil-gas  concentra-
   tions  from  groundwater  data
   using Henry's constant. For ben-
   zene, the equilibrium  soil-gas
   concentration with  10 ug/L in
   the groundwater is  -2 ug/L. If
   you inadvertently write it as 2
   ppbv, then you have erred by 300

 • Comparing  on-site results  in
   units of ug/L to off-site results
   reported in ppbv. If the off-site
   confirmation samples show hits
   at 100 ppbv and the on-site data
   were all below detection at a DL
   (detection level) of 1 ug/L, don't
   panic. The results agree.

• What's an easy way out of unit-
conversion madness?
 • Instruct your lab on what units
   and detection levels you want
   the data reported in.

 • Go to for a
   handy-dandy, easy-to-use unit
   conversion spreadsheet.

• What are "vapor clouds" and why
should we care about them?
Vapor clouds refer to  situations
where there is subsurface contamina-
tion of the soil vapor with little or no
coincident soil or groundwater conta-
mination, hence  the term "cloud."
They arise from leaking vapors, not
from contaminated soil or ground-
water. Common  sources for vapor
clouds are sites that contain surface
sources of chlorinated solvents (e.g.,
vapor degreasers, dry cleaners, clari-
fiers), where the dense chlorinated
vapors enter the  vadose zone from
above, or where vapors are leaking
out of USTs.

                                                                               November 2004 • LUSTLine Bulletin 48
    You  should care about vapor
clouds for a number of reasons. First,
unlike groundwater,  vapors  can
move in all directions, regardless of
the groundwater gradient, and move
quickly—approximately 25 feet/year
by molecular diffusion alone. So, a
vapor cloud from a dry-cleaning
washer   unit  can move  laterally
underneath adjoining businesses in a
strip mall within one year and repre-
sent an upward migration threat to
nearby residences within a few years.
    Vapors leaking from an UST can
move downward through the vadose
zone to the groundwater and repre-
sent a groundwater  contamination
threat. (See "The Downward Migra-
tion of Vapors," LUSTLine #29  and
"The Great Escape from the UST,"
LUSTLine #30 for discussions of this
    When  the  J-E model  under-
predicts the measured risk, or indoor
air results don't match with ground-
water patterns, or when vertical pro-
files of  the  soil gas  don't show
increasing concentrations with depth,
vapor clouds should be  suspected
and soil-gas data, not soil or ground-
water data, must be collected to ade-
quately assess the upward vapor risk
    Finally,  as  pointed  out by  a
reviewer  of this article from the rainy
south, while vapor sources can exist
anywhere,  vapor clouds are more
likely to  exist in areas with  deeper
groundwater and less rain. In areas
with shallow groundwater and abun-
dant rain, any leaking vapors are
more likely to get scrubbed (parti-
tion) into the groundwater (similar to
a "Mister Coffee").

• Is it true that an equation written to
allow passive soil-gas data to be
converted to concentration units is now
applicable for vapor-intrusion
Yes and no. It is true that an equation
has been  written by a firm providing
passive soil-gas services. The analysis
of passive soil-gas samplers gives the
mass on  the passive collector (e.g.,
micrograms [ug] or some other form
of relative units), not concentration.
Concentration is mass/volume. So, to
convert mass to concentration we
must know the volume of vapor  that
comes into contact with the adsor-
bent during burial. There is no way to
know this and no accurate way to
measure this volume on a true pas-
sive  sampler.  Therefore  passive
soil-vapor  data  cannot  be used
for  quantitative   upward  vapor-
migration assessment, despite what
you might be hearing. One could
pump a  known  volume  of  air
through a passive collector, similar to
the NIOSH methods or TO-17, but
this is far different than simply bury-
ing a collector into the ground and is
actually a form of active soil-gas  sur-

•  Why weren't you more bullish on
flux chambers in your last article?
The primary purpose of the article
was to  describe the two common
chamber methods (i.e.,  static  and
dynamic), how to use them, and the
pros and cons of each. The article was
written in response to  numerous
questions I was receiving from both
the consulting and regulatory com-
munities about the technique.  But
the  overriding problem  with  the
approach is whether chambers can be
located properly. In many structures,
the primary entry of soil gas into the
structure is through discontinuities in
the floor slab (e.g., cracks,  holes,
sumps), and these locations might be
concealed by barriers such as floor
coverings, walls, and stairs.
    However, as I wrote in the arti-
cle, I think flux chambers have their
place when the right conditions exist.
Examples  of   "right  conditions"
include  slabs in  good  condition
with limited pipes/utilities poking
through, larger slabs (i.e., larger than
a typical residence), and undevel-
oped lots in warmer climates or
where estimates of a  future stack
effect due to the  building  can be
    If you elect to use flux chambers,
be sure that enough chamber mea-
surements are collected to get a  rep-
resentative value over  the footprint
of the building (analogous to placing
enough borings on a typical site) and
that they are located near  edges
where the slab meets the footing,
over any zones with more cracks, and
over the center of the contamination,
if known.
    Assuming uniform subsurface
contamination, five chambers might
be appropriate (one on each side of
the structure and one in the center). If
the  contamination is  not directly
below, then fewer chambers on the
side of the contamination might be
appropriate. In all cases, chambers
should be deployed for long enough
periods to enable temporal variations
to be assessed, similar to indoor air
measurements (8 to 24 hours depend-
ing on the conditions; 24 hours if
large temperature differences exist
between day and night).

• Why do you recommend small
purge-and-sample volumes for soil-gas
Multiple reasons. I too often see soil-
gas data from large Summa canisters
(3L to 6L) with tracer/leak  com-
pound detections. (By  tracer/leak
compound, I am  referring  to  a
compound  such  as   butane  or
isopropanol, deliberately  applied
during sample collection, that acts as
a tracer of leaks  from the surface or
leaks in the sampling system.) Also,
successive duplicate  samples (i.e.,
one collected after the other) show
larger  variations  than  duplicates
collected  with  smaller  volumes.
Remember, the larger the volume col-
lected, the greater the uncertainty as
to the source of the sample. (See Fig-
ure 1.) That's a plain fact.
    So, if you are sampling near the
surface, large extraction volumes will
increase  the  potential that  atmos-
pheric air might be drawn down the
outside of the probe body. If you are
sampling under a slab, large extrac-
tion volumes will increase the poten-
tial that samples might  be  from a
deeper depth or  outside the  slab. In
addition, large  purge-and-sample
volumes can create vacuum condi-
tions that cause  contaminant parti-
tioning from the soil into the soil gas.
    All of these  issues increase the
potential that the collected soil-gas
sample is not representative of in-situ
soil vapor at the target depth.  Finally,
the larger the volume required, the
larger and more complex the  sample
collection system required (e.g., vac-
uum pumps, larger sample contain-

• What about when air labs tell me I
need to collect 6L volumes to reach my
required DL?
You shouldn't need to. Soil-gas DLs
for  VOCs of 0.2 to 0.5 ppbv (~ 1
ug/m3 for most compounds) can be
reached with only 300 cc of  sample
(as reported to me by a nationwide
air  lab) using method TO-15, and
                • continued on page 14

LUSTLine Bulletin 48 • November 2004
• Vapor Intrusion from page 13

with volumes as small as 50 cc using
methods 8260  SIM or 8021. Yes,
larger  canisters are useful in case
repeated runs are required. But, for
the TO-methods, one to three liters
should  be  more than sufficient to
enable  re-runs, if  necessary.  For
methods 8260 or 8021, 500 cc should
be more than sufficient.

• Is it true that the toxic organic (TO)
methods are the only appropriate
method for analyzing soil-gas samples?
No, but you may be hearing this from
some of the labs that specialize in
these analyses. The argument is that
EPA methods such as 8260 and 8021
are soil and water methods that use
liquid standards and hence are not
appropriate for air samples. Further,
according to the argument, soil-gas
samples are air samples and, thus,
should be analyzed by air methods
that use gaseous standards. The key
difference in the methods is not the
type  of standard   but  how   the
standard and sample are introduced
into the analytical instrument.  TO-
methods use air concentrators. Meth-
ods 8260 and 8021 use direct injection
or purge-and-trap injection systems.
    For the majority of compounds of
concern at vapor-intrusion sites (e.g.,
BTEX, chlorinated solvents), there is
no significant difference caused by
the injection methods. For some com-
pounds (typically the more polar
ones such as ketones and alcohols),
methods 8021 and 8260 can give dif-
ferent values from the TO-methods
by up to a factor of two to three if the
FIGURE 1.  A basketball or a baseball? The 6L Summa canister has a volume about the size of a
basketball, whereas the mini-can has an approximate volume of a baseball.
purge-and-trap  injection  method
with liquid standards is used. In the
cases where this might be an issue,
either use the TO-methods or ask the
laboratory to use vapor standards for
8260 or 8021.
    The decision on what analytical
method to use should be based pri-
marily  on the required detection
level, project scope, and cost—in this
order. See Table 1 to help you decide.
    For example, if the compounds of
concern at a site are only TCE, PCE,
TCA, and DCE, then the GC-ECD is
more than likely to reach  the DLs
required and it costs one-third what a
TO-15 SIM would cost. And yes, the
data will be legally defensible if the
Summary of Analytical Methods for VOCs in Soil-Gas Samples
8021 for MTBE/BTEX
8260 SIM
10 to 20
5 to 10
1 to 5
0.01 to 0.05
0.5 to 5
$ 75
$ 100
$ 150
$ 90
False positives if high TPH
Complete VOC list & naphthalene
Subset of 5-10 compounds#
Complete VOC list, no naph.
Subset of 5-10 compounds#
Chlorinated compounds only
* Listed price are estimated and will vary around the country.
# You select the subset from the full VOC list.
lab follows the method QA/QC.

•  Why do you promote on-site analysis
so heavily?
Mostly  because  on-site  analysis
allows you to use your brains in real-
time. This is especially powerful for
vapor-intrusion assessments because
additional locations can be added,
either spatially or vertically, based on
the real-time data. It also allows mis-
takes (e.g., leaked gas breakthroughs,
inconsistent  numbers,  hardware
blanks) to be recognized on-site and
verification or replicate samples to be
collected  as needed.  Laboratory-
grade instruments, including mass
spectrometers,  can be transported
into  the field, and they fulfill neces-
sary  analytical protocols.

•  Isn't your opinion biased, since you
provide on-site services?
Yes,  but not for this reason. The real
reason for any bias is the power that
real-time data and decision making
bring to assessing this  risk path-
way—and I'm not the only one who
feels this way. A growing number of
federal and state regulatory agencies
and consultants are hopping on this
bandwagon. In fact, EPA has a real-
time, instantaneous analyzer called
the Trace Atmospheric Gas Analyzer
(TAGA) that staff actively promote
and  use on  vapor-intrusion sites.
Also, EPA is a strong supporter and
promoter of the  Triad  approach
that   includes   on-site  analyses

                                                                                  November 2004 • LUSTLine Butter
(See "LUST Innovations, TRIAD, and
Computer Imaging Move LUST Site
Investigation into the 21st Century,"
•  Why are you so worried about the
hardware required by the TO-methods
for soil-gas samples?
For a number of reasons, primarily:
 •  There are many connections and
    fittings, all with dead-volume
    and  possibilities of  leaks. (See
    Figure 2.)

 •  More hardware means more can
    break, have blanks, or not work

 •  Few field technicians or field-
    sampling  companies have the
    experience of testing and using
    the hardware properly or fixing
    or repairing it if problems are
 •  Often, the connecting  fitting/
    tubing or flow chokes are reused
    between samples without being
    cleaned. Very recently, a lab pro-
    vided me 30 canisters for a pro-
    gram with only two flow chokes
    (one to use plus a spare). What's
    wrong  with  this  picture?  If
    you're  reusing  flow   chokes
    between samples, how do you
    know that they are not contami-
    nated from the previous sample?
    At a minimum, a cleaning kit and
    instructions on how to clean the
    flow  choke between samples
    should have been included.

    Throw into this mix the bulkiness
of the hardware (ever tried to put six-
teen 6L canisters in your car?), and
hopefully you  can understand my

•  I keep getting tracer/leak gas
detections in my samples, and the
regulators are not accepting the data.
What am  I doing  wrong?
The problem probably stems from any
one or all of the following scenarios:
 •  Collecting too large a volume of
    soil-gas sample  (>1 liter) too
    close to the surface

 •  Not  adequately  sealing at the
    surface of the ground where the
    probe rod enters
 •  Leakage at the coupling inside
    the probe rod, if the post-run tub-
    ing method is being used
FIGURE 2. Comparison of a sampling train provided by a lab to fill canisters for off-site analysis
vs. a syringe used for on-site analysis. The larger dead-volume and numerous connections of the
sampling train increase the chances of equipment blanks and leaks.
  •  Using a permeable tubing to col-
    lect soil-gas samples

  •  Loose fittings on your sampling
    system train

• What tubing do you recommend?
Rigid-wall, nylon  tubing,  1/8" or
1/4" outer diameter. Believe it or not,
Teflon, while inert, has a relatively
high sorption for many compounds.
The 1/8" nylon  tubing is easier to
work with than  the 1/4" tubing if
soil-gas sampling is your only need.
If permeability testing is desired, the
1/4" tubing is better. Stainless-steel
tubing is fine for shallow sampling
but is logistically more difficult to
install  as  the  sampling depth
increases (>5'). Flexible tubing (e.g.,
rubber, plastic),  such as the  type
available  on rolls at the  hardware
stores, or tygon  tubing  should be
avoided at all costs (too permeable).

• What is an "alpha factor," and how
do I use it when trying to scope a vapor-
intrusion project?
An alpha factor is a unitless empirical
attenuation factor relating  the indoor
air concentration to either a subsur-
face soil-gas concentration (asg) or to
a groundwater concentration (agw) as
    (OCSgj — *—indoor' ^-soil gas

    v™gw/ ~~ ^-indoor' v^-water  ^V

    H  is the compound's  unitless
Henry's law constant.

    U.S.  EPA and most oversight
agencies have tabulated acceptable
levels for compounds in breathing air
for various risk levels (Cini-joor). So, if
you know  the alpha factor that the
oversight agency allows for soil gas
or groundwater, you  can calculate
the required "fail level" and hence,
detection level for the compound in
either the soil gas or groundwater.
Let's try one to see how it works:

   From Table 2 of the EPA draft vapor-
   intrusion guidance, the allowable air
   concentration for benzene at a 1 in a
   million risk level is 0.31 ug/mZ. For
   soil-gas samples  collected at 5 feet
   below the structure, the default alpha
  factor from Figure 3a of the guidance
  for sandy  soils is 0.002. What is the

                • continued on page 16

LUSTLine Bulletin 48 • November 2004
• Vapor Intrusion from page 15

   soil-gas "fail level" and what analytical
   method(s) could be used?
   Rearranging the first equation

   '-soil gas - ^indoor' ' asg'
   0.31/.002 = 155 ug/m3

   From Table 1 in this article, we
   see  that all the methods  can
   reach this detection level.

   But, for sub-slab  sampling, the
   EPA draft vapor-intrusion guid-
   ance uses a default alpha factor of
   0.1. Now what is the soil-gas  "fail
   level" and what methods suffice?

   Soil-gas "fail level" = 3.1 ug/m3

   Analytical methods = 8260 SIM,
   TOM, or TO15

• What is  the EPA vapor-intrusion
"dead zone"?
Well, to be honest, it's my own term
to describe the lack of direction in
EPA's draft vapor-intrusion guid-
ance  on  what  sampling  to  do
between 5 feet and the sub-slab (in
review of this article an EPA repre-
sentative called it the "No Predictive
Modeling Zone"). This amounts to a
4 1/2' gap  in the vadose zone where
there is no instruction. And yet, this
is an important zone.
    A number of key processes influ-
encing the soil-gas concentrations are
active in this zone, including bioat-
tenuation, surface reaeration, baro-
metric pumping, and infiltration of
surface precipitation. Vertical profiles
of soil gas adjacent to or under struc-
tures can  be very informative and
demonstrate that attenuation of the
contaminant is occurring. Agencies
should allow  and encourage these
data. The  San Diego County Depart-
ment  of   Environmental  Health
(DEH) is currently writing regulatory
guidance and protocols for the "dead

• What is  your opinion on sub-slab vs.
near-slab sampling?
The default approach right now by
some agencies is to collect sub-slab
soil-gas samples and apply an alpha
factor of 0.1 to 0.01. But sub-slab sam-
pling has its share of problems.
    Operationally, sub-slab sampling
is easy to  do. But for the responsible
party (RP), sub-slab  sampling can
definitely be a  "Prozac moment."
First, sub-slab  sampling is much
more intrusive than outside sampling
and,  more likely  than not,  will
require access agreements and attor-
neys, especially if you are an RP with
deep pockets. Second, the  proper
alpha factor to apply is not known, so
the significance of detected values is
not clear, and you may over exagger-
ate the risk. Third,  sub-slab data
alone give you  no information on
what is going on below in the vadose
zone towards the source.
   For these reasons,  I typically rec-
ommend  that clients  refrain from
sub-slab   sampling  at  the start.
Instead, I prefer to collect soil-gas
data around the structure  for an
underlying source (e.g., groundwater
contamination), or on  the side of the
structure towards the source for a lat-
eral  source (e.g., adjoining ground-
water or  soil contamination or a
vapor cloud),   in  an  attempt to
demonstrate there  is  no potential
risk.  If  oxygen levels are high,
groundwater levels are not within
two  feet of the structure (e.g., base-
ment, slab, crawlspace), and areas for
air penetration exist around the slab
(e.g., lawns and  gardens), then
chances are high that reaeration is
occurring under the slab, and near-
slab  data  will be representative of
sub-slab,  especially for residences
with small slabs.
   Remember  also that contami-
nants in the vapor phase, like balls
and groundwater, cannot run uphill
and  accumulate under a  slab at
higher concentrations than the source
concentration. In other words, the
very highest the sub-slab soil-gas
concentration can be is the same as
the  soil-gas concentration  at  the
source. So, assuming a groundwater
source, if  you measure the soil-gas
concentration just above the ground-
water, the sub-slab concentration can
be no higher, even with preferential
pathways. If  the  risk calculation
passes using this measured value,
you  need not collect  sub-slab sam-
   Likewise, if you measure the soil
gas midway between the source and
structure, the soil-gas concentration
will  be approximately one-half the
source concentration  assuming a
homogeneous vadose zone with no
advection. So if measured values all
around the structure  at  the mid-
depth agree, and the risk calculation
passes by more than a factor of two,
sub-slab sampling is likely not neces-
sary unless you have reason to sus-
pect a preferential conduit.
    If you must go sub-slab, try to
stay in garages (if technically sound)
to do  so.  And remember, collect
enough samples to get a representa-
tive value under the slab. EPA rec-
ommends three sub-slab samples per
domestic residence to characterize
spatial variability, although I person-
ally think one per side and one in the
middle is better (total of five).
• What's this I'm hearing about using
radon gas as a natural tracer?
As mentioned previously, the diffi-
culty with sub-slab soil-gas data is
that the  alpha factor is not really
known and regulatory default values
tend to be conservative, so use of
them  may overestimate  the risk.
Measurement of naturally occurring
radon  inside  the structure and sub-
slab can allow a site-specific alpha
factor  to be calculated that may be
considerably less  than the  value
allowed by the regulatory agency.
That same alpha factor can then be
used to estimate the indoor air con-
centration of the contaminant of con-
cern, assuming that all vapors are
entering the building at equal rates.
    Keep in mind that like all the
other tools being  used for vapor-
intrusion assessment, radon has its
limitations too. First, and perhaps
foremost, you must have radon in
high enough concentrations to be
useful. Then  there's a host of other
questions:  Are there  any  inside
sources of radon (e.g., cement block,
granite stone, and  shower water)?
How will the values vary with baro-
metric pressure fluctuations? From
season to season? And remember,
indoor and sub-slab samples create
access  headaches. Nevertheless, if
you are already collecting sub-slab
samples, concurrent  collection of
radon data may prove useful, and it
does not cost a great deal (<$100 per
• Are hydrocarbons really
bioattenuating  in the shallow vadose
zone, or is it propaganda by the oil
companies in an attempt to minimize
their vapor-intrusion problems?
A vast number of studies have been
performed that clearly demonstrate

                                                                                       November 2004 • LUSTLine Bulletin 48
the bioattenuation of hydrocarbon
vapors in aerobic soils. Many, but not
all of these studies, were performed
by the oil industry (go to www.API.
org to read published studies). In gen-
eral, the studies show that when oxy-
gen levels are 10 percent or greater
and at least two feet of vadose zone
exists  between  the   contaminant
source and the overlying structure,
the hydrocarbons  aren't likely to
pose  an unacceptable risk. (A pub-
lished  study  by  the  New Jersey
Department of Environmental Pro-
tection suggested oxygen levels as
low as 6 percent are sufficient).
    While there is a current effort to
try and quantify the bioattenuation
process and add a quantitative term
to the existing  models,  it is  more
likely to expect that the bioattenua-
tion rate will be extremely site depen-
dent. The more accepted  alternative
is to  document that this process is
occurring by collecting vertical pro-
files of the soil gas for the hydrocar-
bons, oxygen, and carbon dioxide.
    If shown to occur, some agencies
are conservatively allowing a  factor
of 10 to 100 reduction in the  alpha
factor. EPA-OUST currently  has a
technical workgroup  consisting of
EPA  and state regulators studying
this   issue  with the  intention  of
preparing guidelines or recommen-
dations on assessing vapor intrusion
at hydrocarbons sites.
    To document that bioattenuation
is occurring,  I  recommended that
data be collected at a  minimum of
three locations vertically in the  upper
vadose zone to ensure that vertical
variations  are  characterized  ade-
quately. If repeated data are  desired,
install    vapor-monitoring    wells
(implants) for easy resampling.

• What are the best current
documents, including regulatory,  on
soil-gas collection for vapor intrusion?
  •  The most comprehensive regula-
    tory document for the collection
    of soil-gas samples was written
    by California EPA (Department
    of Toxic Substance Control) in
    conjunction with the Regional
    Water Quality Control Board in
    January 2003. gov/PolicyAnd-

  •  The San Diego County DEH Site
    Assessment Manual has soil-gas
    collection guidelines for a variety
    of soil-gas applications, includ-
    ing upward  vapor risk. These
    guidelines are  not step-by-step
    protocols, but they present gen-
    eral issues that need to be consid-
    ered and fulfilled.

  •  The  API  has written a  soil-gas
    sampling document and has a
    number of papers on bioattenua-
    tion, J-E model, and other related
    http://www.api. org/bulletins

  •  EPA-ORD (Dr. Dominic DiGu-
    ilio) recently released a sub-slab
    soil-gas sampling standard oper-
    ating procedure (SOP) that  is
    available on the following Web
    site:   (
    cfm ?pageID=document).

  •  SOPs   for  vapor  monitoring
    well/implants installation, sub-
    slab  soil-gas sampling, deeper
    soil-gas  sampling,  and   flux-
    chamber sampling are available
    on my Web site, as well as links
    to most of the above documents
    and Parts 1 and 2 of this series of
    LUSTLine articles.

    I wish to thank my reviewers on
this article for their constructive com-
ments, including  Henry Schuver,
Rafael Cody, Rod Thompson, Craig
Dukes, Tom Scott, Larry Probe, Todd
McAlary,   Gina   Plantz,   Victor
Kremesec,  John   Menatti,  Roger
Brewer, and Louise Adams. •
 Blayne Hartman, Ph.D., is a partner of
  H&P Mobile Geochemistry (formerly
  HP Labs), a firm offering on-site sam-
  pling and analysis. He has lectured on
 soil vapor methods, data interpretation,
  and vapor intrusion to over 20 state
 agencies, to all of the U.S. EPA regions,
  and the DOD. Blayne has authored
 chapters in four textbooks on soil vapor
   methods and analysis. He has con-
    tributed more than ten articles to
  LUSTLine since 1997, and this is his
 fifth article on vapor intrusion-related
    issues. Blayne can be contacted at
 bhartman® or check
          out his Web site at
 120 Years from page 5
What Does The Future Hold?

I dream of leak-free tank systems, the
end of operator error, gasoline in the
tanks and cars and not in the environ-
ment (or better yet, vehicles propelled
by something better for the environ-
ment), and	ZZZZZZZ. Actually,
I'm too tired to dream. But for now,
we're hanging in there, and we've got
the program with the most "interest-
ing" acronym. Go LUSTBusters! •

 Patricia Ellis is a hydrologist with the
    Delaware Department of Natural
 Resources and Environmental Control
 (DNREC), Tank Management Branch.
 She has a regular column in LUSTLine
   called "WanderLUST." Pat can be
 reached at

Ellis, Patricia, 2003. A Hot Dog by Any Other Name
 Could Be Your Drinking Water. LUSTLine Bulletin
 44, July 2003, pgs. 1-6.
Federal Regulations, 1988, 40 CFR 280  - Under-
 ground Storage Tanks - Final Rule as of 9/13/88
 http:// swerustl/fedlaws/cfr.htm#
Gray A. and A. Brown, 2000, Fate, Transport And
 Remediation Of Tertiary Butyl Alcohol (TEA In
 Groundwater (Abstract) In Ground Water: Preven-
 tion, Detection, & Remediation Conference and Exposi-
 tion. Special focus: Natural Attenuation and Gasoline
 Oxygenates, November 14, 2000, Anaheim, Califor-
 nia; P278
NEIWPCC (New England Interstate Water Pollution
 Control Commission), 2000, Survey of State Experi-
 ences with MTBE Contamination at LUST  Sites, June
Sakata, Rachel, and Mike Martinson, 2001, Update on
 State MTBE Regulatory Standards  & Guidelines:
 Drinking Water & LUST Cleanup. Presented at 13th
 Annual UST/LUST National Conference, March 20,
TPH Criteria Working Group, 1997, Total  Petroleum
 Hydrocarbon Criteria Working Group Series, Vol. 4:
 Development of Fraction Specific Reference Doses (RfDs)
 and Reference Concentrations (RfCs)for Total Petroleum
 Hydrocarbons (TPH). Amherst Scientific Publishers,
 Amherst, Massachusetts, 137 pp.
U.S. EPA, 2000, Memorandum from Sammy Ng,
 OUST to Regional  UST Program Managers and
 State UST/LUST Program Managers: Monitoring
 and Reporting of MTBE and Other Oxygenates at
 UST Release Sites, January 18, 2000.
U.S. EPA, 1999, Use of Monitored Natural Attenuation at
 Superfund, RCRA Corrective Action, and Underground
 Storage Tank Sites, Directive Number 9200.4-17P.
U.S. EPA, 1997. Expedited Site Assessment Tools For
 Underground Storage Tank Sites: A Guide for Regula-
 tors,   (EPA   510-B-97-001),  March   1997.
U.S. EPA, 1995, Use Of Risk-Based Decision-Making in
 UST Corrective Action Programs, OSWER Directive
 9610.17 March 1,1995.
Weaver, James W., and John T. Wilson, 2000, Diving
 Plumes and Vertical Migration at Petroleum
 Hydrocarbon release Sites. LUSTLine Bulletin 36,
 November 2000, pps.12-15.

LUSTLine Bulletin 48 • November 2004
    (       (Vermont  Vapor Stories
    I       JThe  Evolution of Vapor-Release
     S   /
       \   (  Assessment Techniques
by Andrew Shively

    Since February 2002, the Vermont
    Department of Conservation's
    (DEC's) UST program has dis-
covered situations that represent
acute or chronic releases of vapor-
phase petroleum from UST systems.
Since our initial investigations, we
have grown increasingly concerned
that underground petroleum vapor
releases (UPVRs) have the potential
to significantly impact human health
and the environment. Our experience
seems to  support findings  in New
Hampshire  and  California,  (see
LUSTLine #46 and #47); however, the
topic is still in its infancy, and more
knowledge is needed to nurture a
greater understanding of the poten-
tial impacts, investigative tools, and
remedial solutions in UPVR scenar-
   The LUSTLine #47 article  titled
"Tracking Troubling Vapor Releases
in New Hampshire"  discusses  the
relationship of UST system pressur-
ization and vapor releases.  The
research  conducted by the  New
Hampshire Department of Environ-
mental Services (NHDES) provides a
shot of adrenaline to our body of
knowledge on the topic. The study
documents the chronic and dynamic
force of very low pressure within
UST ullage systems, presents a reme-
dial technology that can be used to
control the ullage system pressure,
and demonstrates the reduction of
volatile organic compound (VOC)
impact to groundwater. I would like
to help reinforce our information
base by providing a framework of
specific elements and techniques that
should be considered when deter-
mining if  UPVRs are a suspected
source of petroleum contamination at
a facility.
   In the beginning, it was hard to
imagine how a little gas vapor from
the in-tank monitor (ITM) probe riser
could cause groundwater contamina-
tion. In fact, as late as 1998, few peo-
ple in the business paid any attention
to a little gas vapor under an UST-
system manhole. How many times
did a seasoned UST inspector open
an uncontained vent-riser manway
and note moderate gasoline vapors?
Plenty I'd say. Almost routinely. But
the vapor concentrations were also
routinely and quickly dissipated after
the manway was allowed to remain
open, and with no apparent liquid
source, the potential threat of impact
was dismissed.  That was the para-
digm we operated under until early
2002, when an incident occurred that
expanded our awareness to include
vapors  as a possible source of petro-
leum compound impact to human
health and the environment.

An Explosive  Episode in
Paradigm Progress
In late February 2002,1 was notified
that intermittent but significant gaso-
line vapors  were inundating the
indoor  air space of a retail gasoline
facility in northern  Vermont. The
UST owner  contacted  the  DEC
because he had recently discovered
that the back room of his facility had
been filling with gasoline vapors dur-
ing evening deliveries. He had not
been informed of this fact until the
night staff started complaining to the
   The manager learned that over a
period  of a several months, every
time gasoline  was delivered, the
uninsulated back room would reek of
gasoline vapors. The night staff had
temporarily solved the problem by
venting the back room—a good idea,
since that was where they took ciga-
rette breaks during the  cold (and I
mean cold) winter nights. Since the
vapors  diminished after delivery and
venting, little was said about the con-
   Upon my arrival,  several initial
steps had been taken to reduce the
indoor  air impact and diagnose the
cause. An air-purifying unit had been
installed in the back room to reduce
overall VOC concentrations inside
the building. A soil-vapor extraction
(SVE) vent leg and high-vacuum
motor with carbon treatment had
been installed adjacent to the build-
ing in the area where the electrical
conduits from the tanks entered the
back room—Area of Concern #1
(AOC #1)—and an initial UST system
evaluation had been conducted by
the consultant.
   The initial evaluation revealed
the following:
 • An in-tank monitor (ITM) probe
   communication wire had been
   installed  such  that  gasoline
   vapors could easily escape and
   accumulate in the subgrade man-
   way of the probe riser.

 • The  electrical conduit junction
   box for the ITM communication
   wire and the UST interstitial sen-
   sor wire were not sealed, allowing
   vapors to migrate preferentially
   toward the building.
 • The  routine UST  compliance
   inspection did not reveal any liq-
   uid  release  sources  from  the
   gasoline USTs.
 • The UST and Air Pollution Con-
   trol (APC) regulatory require-
   ments were in compliance.
 • No gasoline spills had  been
   reported in the area of the facil-
   ity, and no visual indications of
   small  unreported  spills  were

   Based  on the observed status of
the UST  features and lack of an
observable or reported spill, a liquid
release was concluded to be unlikely.
The owner agreed to and arranged
for a helium test to determine if any
additional or less obvious vapor-
release sources existed. The only sig-
nificant helium source identified was
the previously mentioned ITM probe-
riser communication wire fitting. The

                                                                               November 2004 • LUSTLine Bulk;
FIGURE 1.  ITM and interstice risers with electrical junction box, post repairs. Note LIST
system backfill.
LUST Sites Calling
Clearly, the scenario described above
represents a potential human health
impact—200 to  300 ppm  VOC in
indoor air is nothing to dismiss. The
1996 Threshold Limit Values (TLVs)
for gasoline, as published by the
American Conference of Governmen-
tal Industrial Hygenists (ACGIH),
identify gasoline as a carcinogen and
adopt   a  time-weighted  average
(TWA) exposure value of 300 ppm
with a short-term exposure  limit
(STEL), or ceiling, of 500 ppm for air-
borne contaminants. At the time of
the incident, the  indoor air contami-
nant levels were taken very seriously,
but the connection of a  petroleum
vapor  release  to  a groundwater
riser was contained in a 24" shallow
manway with the UST system back-
fill exposed. (See Figure 1.)
As part of the emergency
response, the SVE system was oper-
ated to reduce VOC impact to indoor
air space. VOC influent concentra-
tions measured during active SVE
system operation declined from 200
to 300 parts per million (ppm), as
measured by a photoionization
detector (PID) at start-up, to 30 to 40
ppm within a few hours of operation.
The SVE remained in operation until
the helium test could be conducted
and was shut down during testing.
Following testing and repairs to
the ITM communication wire assem-
bly and the junction box, a post-
repair SVE start-up test measured no
detectable influent VOCs by PID.
Additional monitoring of the SVE
system operation over the following
week found no detectable influent
VOC concentrations, and the emer-
gency remedial equipment was dis-
mantled and removed from the
Groundwater monitoring con-
ducted on the site indicted that no
discernible additional impact of
groundwater had occurred in the area
of the SVE system, but a new previ-
ously unknown plume of methyl-fert
butyl ether (MtBE) in groundwater
was identified in another isolated
area of the site (AOC #2). The com-
mon thread connecting AOCs #1 and
#2 to the vapor release source location
was electrical conduits for the ITM
and interstice sensors for a diesel UST
installed in a separate excavation
from the gasoline USTs.
The certainty of concluding that
the new MtBE plume in groundwater
was from the vapor release at the
gasoline UST appears logical but not
conclusive. What is certain, however,
is that an underground petroleum
vapor release can occur from an UST
system, and it can cause significant
human health impacts that require
emergency corrective action. Further-
more, the force driving the emission
of vapors appears related to delivery
impact seemed less certain — at leasi
until our next reported incident.
In October 2003, the DEC Sites
Management Section (SMS) was
notified of extremely high MtBE con-
centrations in groundwater down-
gradient of an active UST system at a
location in Colchester, Vermont. The
MtBE concentrations were the high-
est recorded in the four years oi
quarterly groundwater monitoring
conducted at the site (See Table 1).
The site was monitored for a
baseline of contamination concentra-
• continued on page 20
• FABLE i MTBE Q0ncentratjons |ppjj) jn Groundwater, Colchester







LUSTLine Bulletin 48 • November 2004
 i Vermont Stories from page 19
tions prior to a corrective action feasi-
bility investigation (CAFI), and a
pilot study of remedial options was
scheduled for the fall of 2003. The
groundwater analytical results took a
drastic turn upward during the sum-
mer of 2003. Most unsettling was the
fact that only MtBE seemed to  be
increasing, both  significantly and
suddenly. MtBE-contaminated ground-
water was also infiltrating a storm
sewer   along  the  downgradient
boundary of the site and discharging
to a surface water feature (SS-2). (See
Table 1.) Was this  the lead edge of an
upgradient plume? Was the source
within the tank cavity? Was it a spill?
Was it a UPVR impacting groundwa-
    An inspection conducted at the
facility during the summer of 2002
prior to the request for a CAFI had
not found any  signs  of a liquid
release or spill, let alone significant
compliance deficiencies. APC records
indicated the facility was in compli-
ance with testing and inspection
requirements. The operator main-
tained adequate documentation and
operational release detection. The
peak MtBE concentrations in ground-
water suggested the source centered
in the tank cavity.  A PD test was sug-
gested to determine if a  potential
vapor-phase  release existed and, if
so,  to pinpoint the release location.
The owner agreed to and arranged
for  a PD test with oversight by DEC,
a contractor,  and a consultant. The
test was conducted in late October
    Prior to the PD test,  a routine
inspection was conducted to establish
a baseline of  possible liquid release
sources. The  inspection resulted in
the  same conclusion drawn in 2002—
no   signs  of  a  liquid  release,
unreported spills, or compliance defi-
ciencies. During the test, several pres-
sure-decay  release  sources were
identified, including a misthreaded
vent-riser cap and a compressed cap
gasket. Other decay sources included
loose fill risers at both gasoline USTs
located on site. All of these potential
vapor-release sources were repaired
at the time of the test and the PD test
ultimately passed.
    Groundwater analytical results
following testing and repair showed
a marked decline in MtBE concentra-

FIGURE 2. VOC measurement by PID at suspected vapor release source.
tions, beginning with the monitoring
location immediately downgradient
(MW-2). Over time, it appeared that
the  MtBE  plume  migrated,  as
expected, along  the groundwater
gradient (MW-2 to MW-3) and was
diluted   with    uncontaminated
groundwater, thereby reducing over-
all   groundwater   concentrations
(MW-3 to MW-4). Groundwater dis-
charged  from infiltration into the
storm sewer (SS-2) also declined sub-
stantially following the October test-
ing and repairs.
    The SMS site manager consid-
ered the findings of the inspection
and  the reduction of groundwater
concentrations over time to be indica-
tive of a new release and requested
additional investigation under a sec-
ond $10,000 release deductible. Cur-
rently, corrective action has been
postponed for the site pending ongo-
ing monitoring with declining VOC
concentrations in groundwater (see
Table 1) and declining discharge con-
centrations to surface water.

An Evolving Issue
The vapor-release issue and the sec-
ond deductible came as a shock to the
regulated entity, and, based on the
findings of inspections, testing, and
monitoring, a new "something" had
clearly occurred. That "something"
was clearly a contaminant from a
petroleum storage  system. Signifi-
cantly, the  results  of testing and
repairs appeared coincidental to the
decline of MtBE  concentrations in
groundwater. I began to consider
ways to  bridge that gap between
vapor-phase VOC emission concen-
trations and groundwater analytical
    The PID is an accepted portable
device for direct-read measurement
of VOC concentrations. We felt that
collecting atmospheric and below-
grade, vapor-phase VOC concentra-
tions would provide us with a useful
set of data to  determine the relative
significance of detected vapor-phase
VOC  emissions from tank-top fea-
tures and to help pinpoint the source
of the emissions in an effort to make
immediate repairs. The  process
would be to screen for atmospheric
VOC concentrations before opening
features, immediately upon accessing
features, and during the incremental
increase of UST ullage system  pres-
sure  using  pressure   decay  test
methodology. (See Figure 2.)
    The most obvious isolated sub-
surface areas of UST systems are the
below-grade  features contained in
manways and sumps. Ancillary riser
manways are generally uncontained
(open bottom) and installed within
the system backfill underlying the
concrete pad.  These types of features
include vent-extractor risers, Stage I
vapor-recovery  poppets,  in-tank-
monitor risers, and  unused risers.
Vapor emission sources could exist at
any uncontained feature connected to
the UST ullage  system, including
Stage II and vent piping. For tank-top
features, a competent concrete pad
with tight manway covers acts as a
cap, forcing emitting vapors to  accu-
mulate in the below-grade atmos-
phere of the capped manway. (See
Figure 3.)

                                                                               November 2004 • LUSTLine Bulletin 48
    Below-grade   access   features
allow for the accumulation and mea-
surement of  VOC emissions  from
tank-top features. The VOC emission
data will assist in determining if a
vapor release is occurring, the rela-
tive  concentration  of  the vapor
release, and the specific source point
of emission.  Other  elements that
impact the certainty of  a  vapor-
source release determination include:
  •  Observed or documented infor-
    mation of UST system configura-

  •  Surface protection  equipment
    features (i.e., contained or uncon-

  •  Backfill material (i.e., compacted
    sand or peastone)

  •  Subsurface migration pathways
    (i.e., electrical conduits and back-
    fill pathways)

  •  Ground water data (i.e., depth to
    groundwater  and VOC concen-

  •  Testing results  (i.e.,  pressure
    decay or helium)

  •  Repairs  (e.g.,   tighten  seals,
    replaced gaskets, additional pipe

    In June 2004 an exercise was con-
ducted at  another LUST  site  with
active gasoline USTs to determine if a
vapor release was occurring. The
SMS  site  manager had been con-
cerned that MtBE concentrations had
been  rising downgradient  of  the
active UST systems. The site manager
suspected the source could be from a
vapor release because only MtBE was
increasing—to the highest level ever
recorded on-site.  A pressure decay
(PD) test was scheduled for mid June
2004.  As part of the PD test, a vapor-
release  screening was conducted
with a PID before test set up, during
pressurization of the common UST
ullage system, and after repairs to
source features.
    Before  the  PD test setup,  the
atmosphere above each UST feature
was screened with a PID to deter-
mine if fugitive VOC  emissions were
escaping the  sealed  manways or if
ambient background VOC concentra-
tions existed that could skew the val-
ues measured upon  access to each
feature. No VOCs were measured by
PID during the atmospheric-assess-

FIGURE 3.  Riser manway with 235 ppm measured at static ullage system pressure.
Note condition of caps and backfill material at the base of the manway.
ment phase of the exercise. During
test setup, all potential vapor emis-
sion sources in subgrade UST-feature
manways were screened with a PID
as the manway covers were removed.
    The VOC  concentrations  mea-
sured  represent VOC values  that
exist under chronic, standard opera-
tional system pressures. Based on the
data presented  in the LUSTLine #47
article, standard  operational  pres-
sures of a Stage II-compliant UST sys-
tems  remain greater  than 0.0 inch
water column (we) and less than 1.0
inch we. More importantly, this sim-
ple screening exercise is repeatable
and  does not require an  induced
increase of ullage system pressure.
    From the setup screening  exer-
cise, three suspected VOC emission
source locations were determined to
exist—the ITM riser for  the  mid-
grade gasoline UST, the ITM riser for
the premium-grade gasoline  UST,
and the vent riser for the premium-
grade gasoline  UST. (See Figure 3.)
Specific emission sources were pin-
pointed at each of these features, and
the ongoing static VOC emission
value was measured.  The PD test
began with the gradual increase of
ullage system pressures to 5.0 inches
we positive pressure. (See Table 2.)
    The VOC emission value exercise
was then repeated at all potential
emission  sources. One  additional
emission source was identified at a
system pressure of 5.0 inches we.
Based on the calculated rate of decay,
the initial PD test was aborted  at 5.0
inches  we, and repairs were made
to  the   identified features  with
measurable VOC emissions. Repairs
  •  Tightening fittings of communi-
    cation wires of electronic release
    detection equipment
  •  Removing and rethreading of
    riser features (riser bar caps) with
    additional (or any) pipe dope
  •  Replacing cap gaskets

                • continued on page 22
Table 2 Pressure-Decay Test VOC Emission Concentrations (in ppm)
5.0" we
Post repair
5.0" we
10.0" we

Mid vent

Prem ITM

Prem vent


LUSTLine Bulletin 48 • November 2004
• Vapor Stories from page 21

    One major advantage of conduct-
ing  this type  of pressure-decay-
assisted vapor-release assessment is
that the VOC emission points can be
itemized, the emission value can be
measured, repairs can be made on the
spot before proceeding, and a VOC
emission reduction can be measured,
real time. (See Table 2.) As a result of
the above exercise, MtBE  concentra-
tions in groundwater immediately
downgradient of the active UST sys-
tem have begun to decline. (See Table
3.) Additional groundwater sampling
is pending.
        MtBE concentrations in
       groundwater immediately
  downgradient of an active UST system.
  (Note the period of concentration reduction
  following pressure-decay-assisted vapor-
  phase assessment and source repair.)
    If  MtBE   concentrations   in
groundwater downgradient of the
active  UST  system  continue  to
decline as a result of the pressure-
decay-assisted vapor-release assess-
ment, the conclusion that a vapor
release was occurring and that the
source of the VOC emission was
repaired, will lead us to a determina-
tion that a vapor-phase underground
petroleum release had occurred.

The Evolution Continues....
The assessments presented include
three examples of what I consider
UPVRs. These are  but three. Addi-
tional UPVR investigations are cur-
rently   underway   at  ongoing
groundwater monitoring sites and
post-active remediation sites. The
degree of certainty in determining
that UPVRs exist varies considerably.
The determination requires time-sen-
sitive information from often differ-
ent regulatory jurisdictions. LUST
site monitoring data, spill data, APC
data, and UST compliance data must
all come together to provide a rea-
sonable certainty that a release has
occurred. These data must also lead
to a high degree of certainty that the
release  can only be  attributed to
underground petroleum vapor-phase
emissions from petroleum UST fea-
    The timeliness  of information
from these four data sources has a big
impact on the degree of certainty.
Sometimes routine  replacement of
caps or general maintenance events
can eliminate vapor sources. These
events  could  be UST-compliance
related or APC-compliance related.
Collecting the UST and APC compli-
ance data and establishing a chronol-
ogy of events enables  a comparison
of MtBE concentrations in groundwa-
ter over time.
    The  groundwater monitoring
results maintained as  part of ongo-
ing, pre- or post-remedial LUST sites
may indicate erratic  MtBE  spikes,
while   the  traditional   benzene,
toluene, ethylbenzene and xylenes
(BTEX) concentrations decline. Some-
times these continued  MtBE fluctua-
tions drive remedial decisions long
after  BTEX standards have been
meet. Conducting a pressure-decay-
assisted  vapor-release assessment
allows us to detect  VOC emissions
values to pinpoint source locations,
                      •  • • •  f
                                  .*.    ••••••••••••••
                                  D    ..		 *
  Ivan  Takes on Tanks  in Florida
                                                                              A These ASTs floated out of
                                                                              their concrete dike area.
  Florida LIST and AST facilities lost a lot
  of canopies and dispensers to wind
  damage. This UST was at a marina and
  exposed by tidal surge. Marinas in gen-
  eral were hit hard, particularly docks
  with dispensers and piping.
                         Photos by Charles Harp
     If you have any UST/LUST-related snapshots from the field that you would like to share with our readers, please send them to Ellen Frye c/o NEIWPCC.

                                                                            November 2004 • LUSTLine Bulletin 48
prioritize   repairs,  and  confirm
source-elimination results. The re-
sults of this effort provide a point in
time in the chronology of LUST-site
data, APC  data, and UST data. If
known VOC emissions  are  elimi-
nated and a substantial reduction of
MtBE concentrations in groundwater
results, the certainty of concluding a
UPVR existed has increased validity.
    The current analysis of UPVR
assessment  results  and  recom-
mended repairs indicate a correlation
with groundwater MtBE concentra-
tion reductions. Ongoing  mainte-
nance of tank-top features can result
in a reduction of chronic VOC emis-
sions at  tank-top  features and a
reduction of MtBE concentrations in
groundwater. But as I stated in the
opening paragraphs, the topic is still
in its infancy, and more knowledge is
needed to nurture a greater under-
standing of the potential  impacts,
investigative  tools, and  remedial
solutions in UPVR scenarios.
    I hope the framework of specific
elements and techniques presented
reinforces our information base when
determining if  UPVRs are a sus-
pected source of petroleum contami-
nation at a facility. Each small step
taken to further understand the topic
will promote greater certainty that
UPVRs are a threat to human health
and the environment and lead to a
greater degree of pollution preven-
tion and resource conservation. •

  Andrew Shively is an UST Inspector
 with the Vermont Dept of Environmen-
  tal Conservation. He can be reached at
Honey,  We Shrunk the  Leaks
Thoughts on Those Small-Time Vapor Releases
by Bruce Bauman

    From recent articles and confer-
    ence presentations there would
    appear to be—at least in several
states—a heightened interest in the
potential  effects  of  subsurface
releases of gasoline vapors from UST
systems. The last couple of issues of
LUSTLine have  included  several
interesting articles that address the
general topic  of "small gasoline
releases," which might  be simply
defined as UST system releases that
are  below  the  stated  minimum
release-detection rates identified in
the federal regulations (i.e., 0.1 - 0.2
   It can be considered a testament
to the success of the state and federal
UST programs that while we used to
focus  on releases of hundreds  or
thousands of gallons of gasoline, the
debate has now moved to examining
the  effects  of comparatively tiny
releases. While it will always be our
goal to minimize the frequency and
amount of all UST releases, it will be
very important at this time for all of
us to better understand the preva-
lence and significance of these kinds
of small  releases. We need to put
them in the context of our overall
goals for UST management. We need
to determine if existing regulations
provide a sufficient framework for
adequately addressing concerns with
this potential groundwater pathway,
or if  new  approaches  might  be
Can We Put Vapor Releases
Into Perspective?
LUSTLine #46 provided a summary
of  the  California  "Field-Based
Research" study, the first study to
suggest that small  vapor  releases
might be occurring in UST systems,
especially those with vacuum-assist
Stage 2 vapor recovery. That article
also summarized a sophisticated and
sensitive release-detection  technol-
ogy that can be used to identify cer-
tain types of releases that are much
smaller than 0.2 gph.
   LUSTLine #47 had a discussion of
some detailed, site-specific field eval-
uations of vapor releases being con-
ducted  by  the  New  Hampshire
Department of Environmental Ser-
vices (NH DEP). NHDES is also in
the process of amending its UST reg-
ulations, including emphasizing the
reduction potential  problems  from
vapor releases. Presentations on this
topic have been  made at recent
national conferences.
   These articles appear to reflect a
perception that is gaining increasing
acceptance—that while we have been
successful in greatly reducing the like-
lihood of liquid releases from USTs
(and very importantly, greatly reduc-
ing the mass of the  release), vapor
releases into the tank pit might also
contribute to groundwater impacts in
some situations. Clearly, there are a
number of case studies that would
suggest this mechanism is real.
   What is not clear, however, is
how prevalent vapor release prob-
lems might be. For example: What
percentage of existing USTs might
have vapor releases? What is the
nature of  those releases  (e.g., the
mass of vapor expelled, the composi-
tion of the vapor, reformulated gaso-
lines versus conventional gasolines)?
What are the potential groundwater
quality impacts of those types of
releases under different environmen-
tal conditions (e.g., type of backfill
and native soils, depth to groundwa-
   While there are interesting obser-
vations regarding vapor  releases in a
handful of sites in a few states, I'm
not certain that we are currently able
to routinely differentiate groundwa-
ter impacts that are caused only by
vapors (versus impacts  that  may be
caused by a combination of other
known  potential  "small release"
sources that may occur from various
parts of the UST system) from opera-
tion and maintenance practices, or
even consumer-related releases.

Will the Real Source Please...
I think most  LUST investigators
would agree that it is frequently very
difficult to determine  the specific
               • continued on page 24


LUSTLine Bulletin 48 • November 2004
• Small-Time Vapor Releases
from page 23

source or sources of gasoline that
have triggered the need for corrective
action at a site. As all the "causes of
leaks" studies show, there are multi-
ple potential sources from various
components of UST systems. Those
studies also indicate that sometimes,
small  releases  of  gasoline (e.g.,
weeps, drips, overfills) may occur at
dispensers, in sumps, or other loca-
tions. It's also known that there can
be routine, small (or less frequently,
relatively large) surface releases from
consumers filling their vehicles or gas
    Individually  and  collectively,
those small releases  may elude the
capability of the release detection
technologies  routinely employed to
meet regulatory requirements.  We
need to keep in mind that all of these
other potential  sources  cannot be
ignored in any holistic assessment of
how  small releases  might impact
groundwater quality.  But, as  our
time/space  continuum  does  not
allow a discussion of the broad topic
of all the types of small releases here,
we'll mainly focus on vapor releases.
    While some of the current vapor
studies  may  be able to make some
initial estimates regarding  the con-
centrations of vapors that might be
released from various parts of an
UST system, it is more difficult to get
a handle on the mass of  vapor dis-
charged from the tank and how those
discharges might vary over time. It is
even more difficult to estimate how
much of that vapor (and which vapor
components)  might  actually  get
transferred to the water table.

Wanted Soon: More Data
It can be expected that biodegrada-
tion would play  a very  significant
role  in  potential  attenuation  of
vapors during vadose zone transport
or at the water table. For example, a
2002 lab study documented the co-
metabolic biodegradation of MtBE
and pentane vapors—pentane is
found in high concentrations in gaso-
line vapors (Dupasquier et al., 2002).
    In one of the most informative
research articles published on this
topic  of  small  releases,  Swiss
researchers (Pasteris et al, 2002)
found that while gasoline vapors
(specifically,  MtBE)  from  a small

NAPL release in a lysimeter would
migrate to a shallow water table (< 2
m from their emplaced source), less
than 1 percent of the  mass of the
MtBE ended  up in the water. This
was sufficient to cause a high concen-
tration of MtBE at the water table
(over 3 ppm) but represented a very
small   mass.   Most  MtBE  was
volatilized, and some was biode-
graded. No petroleum hydrocarbon
compounds  were  detected   in
   While it will always be our goal to
  minimize the frequency and amount
   of all UST re leases, it will be very
  important at this time for all of us to
   better understand the prevalence
   and significance of these kinds of
          small releases.
groundwater in that study, primarily
because of biodegradation.
    A follow-up study (Dakhel et al.,
2003), using different hydrological
conditions and a gasoline with both
MtBE and ethanol, showed much
more MtBE transport to the water
table, perhaps because  of reduced
biodegradation owing to the pres-
ence of ethanol and reduced volatile
losses. While these two  studies are
very  helpful  in  identifying   key
processes regarding small releases,
they have their limitations, and fur-
ther lab  and  fieldwork will  be
required to  fill out our  knowledge
    To better understand the poten-
tial water quality effects of vapor
releases, it would be very useful if we
had good data from a number of UST
sites that would indicate how much
of the vapor that may escape actually
ends up  at  the water table, versus
how much is volatilized to the atmos-
phere or biodegraded. Clearly, that
will be affected by a number of site-
specific properties, such as the "size,"
intensity, and duration of the vapor
releases, the type of backfill  and
native soils, the type of paving over
the UST, the depth to groundwater,
and possibly factors like the presence
or absence of previous releases at that
    Given our limited  knowledge of
the nature of groundwater quality
impacts from vapor releases, proper
care  should  be   exercised   in
estimating how vapors may have
contributed to groundwater contami-
nation at any existing UST facility.
For example, in a recent incident in
Maryland, a number of private drink-
ing water wells around a UST facility
were  found  to have  MtBE.  (See
related article on page 34.)  Because
the tanks at that facility tested tight,
and because an extensive evaluation
of possible sources indicated there
may have been  some  sources  of
vapor losses, there have been some
presumptions that vapor problems
are the primary source.
    From my limited understanding
of that specific  site, at this  point in
time I'm a little skeptical that vapor
releases have  been the only source of
the groundwater problems. I would
not discount that they may have con-
tributed to some fraction of the over-
all groundwater impacts, but it is far
from  clear that they are the sole
source of contamination.

The Work at Hand
Concerns  about  vapor and other
small releases have prompted the
Maryland Department of Environ-
ment to begin accelerated develop-
ment  of  new  UST  regulations.
Hopefully those regulations will not
be rushed. We need to take  the time
to allow our current, limited under-
standing of  small  releases to be
expanded sufficiently to ensure that
cost-effective, flexible approaches to
this complex problem can be crafted.
    We  should also learn a good bit
more about the characteristics of the
soluble  plumes that can be created
from small releases and how  they
may differ from plumes created by
large  NAPL releases.  Modeling
research by the American Petroleum
Institute and others suggests that the
contaminant mass flux (see LUSTLine
#46, "Flux Redux," or Einarson and
Mackay,  2002))  associated with
plumes  from small releases will be
much less  likely to impact offsite
drinking water wells than plumes
from larger releases (even though
both may have similar concentrations
of dissolved components   in  the
source area).
    As the authors of  the  various
LUSTLine articles on this topic have
indicated, there is still a lot of work to

                                                                                   November 2004 • LUSTLine Bulletin 48
be done before we can truly obtain a
sufficient understanding of what's
going on and when environmental
problems might arise from vapor or
other small releases. To recap, we all
probably agree that vapors can and
do  escape from UST systems and
that, in some cases, those vapors can
impact groundwater quality near the
tank field. There also is likely consen-
sus that vapors  of the more soluble
and less biodegradable gasoline con-
stituents  would present a greater
likelihood of contributing to elevated
concentrations in groundwater.
    We have learned a good bit in the
last few years, and that knowledge
clearly indicates that this  issue is
worthy of more investigation. But
before effective solutions  can be
developed  and  implemented,  we
have a lot of questions to  answer,
  •  Can we reliably detect very small

  •  How  many existing UST sites
    have  similar  problems  with
    vapor releases?
  •  What are "typical" vapor-release
    rates for the existing population
    of UST systems?
  •  Is there a de minimis rate of sub-
    surface release of gasoline from
    an UST system that could be con-
    sidered highly unlikely to result
    in any significant or long-lasting
    degradation  of  groundwater
  •  What do we know  about the
    characteristics of plumes caused
    by  small releases that  might
    influence the kind of corrective
    action required?

  •  What routine UST maintenance
    and   groundwater monitoring
    practices  would  be  the  most
    helpful in preventing problems
    or minimizing problems, should
    they  arise,  and  might  such
    approaches provide an equiva-
    lent level of environmental pro-
    tection as new release detection/
    prevention technologies?

What Is "Vapor-Tight"?
In his remarks at a recent technical
conference,   U.S. EPA  Office   of
Underground Storage Tank Director
Cliff Rothenstein stated that regard-
ing vapor releases, "We need to get to
the bottom of this. We need to find
out the source of the problem and...
make sure systems are both liquid-
and  vapor-tight."    This   is   an
admirable performance goal for UST
systems, but the key issue will be to
   Information from API on Small Vapor Releases
   The American Petroleum Institute and its Soil/Groundwater Technical Task
   Force have been actively investigating various topics associated with small
   releases for several years, and they have ongoing projects that will also help
   us better understand and manage this issue. Visit
   to obtain more information or download some of the following reports:
    • Simulation of Transport of Methyl Tert-Butyl Ether (MTBE) to Ground-
      water from Small-Volume Releases of Gasoline in the Vadose Zone,
      Bulletin No. 10,, June 2000
    • Evaluation of Small-Volume Releases of Ethanol-Blended Gasoline at UST
      Sites, Bulletin No. 19,,
      October 2003
    • Evaluation of Potential Vapor Transport to Indoor Air Associated With
      Small-Volume Releases of Oxygenated Gasoline in the Vadose Zone,
      Bulletin No. 21, December 2004
    • Maximum Potential Impacts of Tertiary Butyl Alcohol (TBA) on Ground-
      water From Small-Volume Releases of Ethanol-Blended Gasoline in the
      Vadose Zone, Bulletin No. 22, December 2004
    • Maximum Potential Impacts of Tertiary Butyl Alcohol (TBA) on Ground-
      water From Small-Volume Releases of MTBE-Blended Gasoline in the
      Vadose Zone (in progress)
determine an acceptable definition of
"vapor tight."
    A closely related question was
addressed in LUSTLine #47 ("The
Limits of Leak Detection"), where
author Marcel Moreau noted the abil-
ity of certain technologies to detect
"phenomenally" small releases. He
wondered if there was a practical
environmental benefit, asking "Can
leak detection be carried  too  far?"
That is a question that must also be
asked about vapor releases. Is there
some threshold level of vapor release
that might be regarded as unlikely to
cause groundwater problems?
    It will take some concerted  effort
by all parties, probably over the next
year or two, to get a sufficiently com-
prehensive understanding about the
nature and potential impacts of small
releases/vapor  releases.  Then we
must  development  management
options that will provide efficient
and cost-effective approaches that are
commensurate  with  the  level  of
health and environmental protection
we wish to achieve. I would expect
that like other aspects of the UST pro-
gram, individual states will  tailor
their response to the nature of the
problem as it is characterized in their
state. We've made a very good start
toward  figuring out this  problem,
and I'm confident that it won't be too
long before we will have come up
with a handful of good solutions. •

  Bruce Bauman, is Soil/Groundwater
  Research Program Coordinator in the
   Regulatory and Scientific Affairs
 Department of the American Petroleum
  Institute. He can be contacted at bau- He gratefully acknowl-
 edges the helpful comments of a number
      of reviewers of this article.

Dakhel, N.; G. Fastens, D. Werner, and P. Hohener,
 2003, Small-volume releases of gasoline in the
 vadose zone: impact of the additives MTBE and
 ethanol on groundwater quality, Environmental &
 Science Technology, 37(10); 2127-2133.
Dupasquier, D., S. Revah, and R. Uria. 2002, Biofiltra-
 tion of methyl tert-butyl ether vapors by cometabo-
 lism with pentane:  modeling and  experimental
 approach, Environmental & Science Technology, 36
 (2); 247-253.
Einarson, M.D., and D.M. Mackay, 2001, Estimating
 future impacts of groundwater contamination on
 water supply wells, Environmental & Science Tech-
 nology, 35 (3), pp. 66 A-73 A
Pasteris, G.,  D. Werner, K. Kaufmann,  and P.
 Hohener,  2002,  Vapor phase transport and
 biodegradation of volatile fuel compounds in the
 unsaturated zone: a large scale lysimeter experi-
 ment, Environmental & Science Technology, 36 (1),


LUSTLine Bulletin 48 • November 2004
Spill Buckets: Mistaken  Expectations?

by Dale W. Stoudemire

"Spill prevention equipment that will prevent the release of product to the environment when the transfer hose is detached from the
fill pipe (e.g., a spill catchment basin)." This is the extent of federal guidance for spill prevention equipment that most of us who regu-
late underground storage tanks were given—many state statutes also reflect this guidance. The concept of a spill catchment basin or
bucket is simple, and several designs on the market fit the concept
exactly, so you might think this was the only guidance we needed.
Well, surprise, it has become increasingly apparent that we had the
mistaken expectation that these buckets would continue to function
with little cost or maintenance for the life of the tank system.
Hints of a Problem
In South Carolina, our first hints of a
problem showed up as we investi-
gated a possible subsequent release at
a site already undergoing cleanup.
Monitoring reports  showed  unex-
plained increases in contaminant lev-
els, but tank and piping tightness
tests indicated that the systems were
tight. In the absence of compelling
evidence, we initially attributed these
increases to errors in the baseline con-
taminant estimations.
    After several quarters of prob-
lems, we began to look for other pos-
sible sources for the contamination.
In one instance, we found that a seal
in a spill bucket had moved out of
position, allowing product to leak out
every time  fuel was leaked from the
hose into the spill bucket. This  dis-
placed gasket was our first discovery
of what threatens to become a large
and costly situation.
    As our inspectors began to see
more spill buckets that had various
problems, beginning in mid-2003 our
program began to  focus on spill-
bucket  integrity  during routine
inspections. If the  condition  of a
bucket  appeared  suspicious,  the
inspector would pour a small amount
of water into the bucket and observe
the level for several minutes. If the
water level  dropped, we assumed the
water was  leaking from the bucket
into the environment. If the leak was
later found to be the result of a leaking
drain that fed back into the tank, the
bucket was not counted as leaking.
    Questions have been asked about
this protocol.  This  "test" was  not
designed as part of a controlled study.
The inspectors were not attempting to
measure the performance of the pop-
ulation of spill buckets. Rather, they
were deciding whether a situation
encountered at an inspection needed
further investigation.

    The  question
of disposal of the
test water has also
been raised. We do
not pour water into
every bucket that
we  inspect.  The
inspector only tests
a bucket  if he or
she is reasonably
certain that it has a
problem. Disposal
of the  water has
not been an issue,
because    almost
every bucket tested
with water turned out to be leaking,
and the water drained out through
the existing hole. Considering that
the holes in the buckets have already
been releasing pure petroleum, the
small amount of water is not consid-
ered a significant problem.
    During this same time period, we
also began to  find  buckets with
severe problems that had developed
since the last annual inspection. We
began to see more displaced gaskets
and large cracks or splits in the buck-
ets, usually in the flexible bellows. In
response to these findings, I decided
to examine the data for trends.

The Study
Even though the data were collected
for routine inspections and not as a
part of a controlled test, examining it
provided useful information. Our
database tracks the inspections and
any violations that we encounter. We
conduct about  4,000 inspections
annually, so a direct examination of
each inspection was not practical. I
looked at the results of 12 months of
inspections in a selected region—a
total of 910 tanks at 337 locations.
    Since  the records for each of
these inspections contained informa-
A spill bucket with a large horizontal split in the plastic bellows. The
brown spot below the tip of the screwdriver is the soil beneath
the bucket.
                 tion on any leaking spill buckets that
                 were encountered, it became a simple
                 matter of counting  the number of
                 tanks with leaking spill buckets and
                 dividing by the total number of tanks
                 with spill buckets to get a percentage.

                 What I Found
                 Of the 910 tanks in the sample, 76, or
                 8.4 percent, had leaking spill buckets.
                 Assuming this population was repre-
                 sentative for the state, I applied the
                 8.4 percent to the entire population of
                 tanks in the state and arrived at the
                 conclusion that an estimated 1,032
                 spill buckets are currently leaking
                 statewide. This means that there are
                 1,032 potential releases that will have
                 to be  reported  and investigated.
                 Some of these investigations will
                 undoubtedly result in the discovery
                 of contamination requiring remedia-
                 tion. Since it appears likely that this
                 problem will worsen over time as the
                 buckets age and continue to degrade,
                 I anticipate we will discover more of
                 these leaks in the future.

                 What I Learned
                 Once I  identified the problem,  I
                 searched for  possible  causes. The
                 answer was surprising—spill buckets

                                                                               November 2004 • LUSTLine Bulk;
are not designed to last for the life of
the tank system. Many spill buckets
are made from high-density poly-
ethelene (HOPE) or have HOPE com-
ponents. As we have learned from
experience  with  flexible piping,
HDPE can degrade from long-term
contact with petroleum.
   According to a representative for
a major  manufacturer, many spill
buckets  installed  for  the  1998
upgrade requirement are approach-
ing the end of their useful lives. In
defense of the manufacturers, I must
say that  I was never told the spill
buckets were designed to last; I only
assumed it.  The representatives I
spoke with have been very forthcom-
ing about the performance of their
products. The mistake was not in the
claims for the performance of the
buckets.  Rather,  it  was in  my
assumptions  about them. Unfortu-
nately, I suspect that many tank own-
ers  and  regulators   share  my

What to Do
There are several things  that tank
owners can do to lengthen the life of
their spill buckets:
 • Check spill buckets after every
   delivery to ensure that spilled
   fuel is removed immediately. As
   many of us have seen, spill buck-
   ets are not always thoroughly
   cleaned  after  catching  small
   petroleum spills. In addition, the
   buckets often contain sand, dirt,
   or debris. According to the man-
   ufacturers, this material, if left in
   the  bucket,  will  significantly
   shorten  the life of the bucket.
   Water and debris  of  any kind
   should be removed  from the
   bucket weekly.
 • Replace  cracked  or broken
   spill-bucket lids immediately.
 • Check clamps and seals regu-
   larly,  and  tighten, adjust, or
   replace as needed. Although I
   have not yet discovered the exact
   cause for it, exposure to  fuel
   seems to  cause the seal on some
   models  to become  displaced.
   Regular inspection and mainte-
   nance should detect this problem
   early and help prevent any possi-
   ble releases.
 • Be prepared to  replace spill
   buckets periodically, and bud-
   get   accordingly.   If  buckets
                                                      A spill bucket with a
                                                      vertical split.   The
                                                      screwdriver is touch-
                                                      ing the soil beneath
                                                      the bucket.
   A completely deteri-
   orated spill bucket.
   More than half of the
   bottom is missing.
   The lid was in place,
   so it is not clear how
   the leaves got into
   the bucket.
    installed in 1998 are nearing the
    end of their useful lives, then a
    six-year replacement cycle might
    be a workable planning guide. I
    learned that, in South Carolina,
    the  cost  of replacing  a  spill
    bucket is around $1,500. On a
    four-tank installation, the owner
    will need to plan on budgeting
    about $6,000 for replacement. On
    a six-year replacement cycle, at
    an average cost of $1,000 per
    year, spill-bucket maintenance
    could cost more than some own-
    ers spend annually on  release

    All of these suggestions are for
the short term. A long-term solution
is for tank owners to insist on spill-
bucket designs that  correct these
problems. They should use their buy-
ing power to encourage manufactur-
ers to select more durable plastics or
corrosion-resistant metals that will
last for a more reasonable period of
time. Current designs could also be
modified so an easy and less expen-
sive replacement cycle could  be

Pay Attention
Many tank owners and regulators
have assumed that spill buckets are
relatively maintenance free and will
last for the life of the tank system. It
turns out that this assumption was
wrong. Spill buckets appear to have a
much shorter life span than some
other tank-system components, so
regular maintenance is required to
extend  bucket  life,  and  owners
should plan for regular replacement.
As regulators, we must emphasize
the condition and functionality of the
spill bucket, not just verify that one
has been installed. •

  Dale Stoudemire is an Environmen-
  tal/Health Manager with the South
  Carolina Department of Health and
 Environmental Control's Underground
 Storage Tank Program. He oversees six
 field inspectors and is a main point of
   contact for the program. He can be
  reached at


LUSTLine Bulletin 48 • November 2004
 Should Remote-Earth Testing  of Galvanic
 Cathodic Protection  Systems  Be Required?
by Kevin Henderson

     Testing of underground storage
     tank UST cathodic protection
     (CP) systems has historically
been one of  the more problematic
aspects of UST regulation. Industry
standards provide a great deal of lat-
itude with respect to exactly how CP
testing is to be conducted. In addi-
tion, very little is prescribed relating
to adequate documentation of such
testing. Therefore, it can be difficult
for regulators to evaluate whether or
not testing and the resultant docu-
mentation is sufficient to indicate
compliance with UST rules and regu-
lations. More importantly, the ade-
quacy of the CP system to effectively
mitigate the potential for a corrosion
failure of the UST system may be in
    In an effort to improve this situa-
tion, the Mississippi Department of
Environmental  Quality  (MDEQ)
developed a guidance document
titled "Guidelines for the Evaluation
of  Underground  Storage  Tank
Cathodic   Protection    Systems"
(MDEQ, 2002). This guidance docu-
ment is intended to foster a more uni-
form approach for not only how CP
testing is conducted but also what
criteria are necessary in order to
"pass" the test. In addition, specific
forms must be completed that pro-
vide documentation on exactly how
the test was conducted so it can be
reproduced and a means for effec-
tively evaluating the methodology/
results of the test.
    One requirement of the MDEQ
policy that is relatively unfamiliar to
many  practitioners is the testing of
galvanic CP systems with the refer-
ence cell placed far away from the
tanks  being  tested. Measuring CP
with the reference cell placed some
distance away from the tanks is com-
monly referred to as "remote" or
"remote-earth" potential. In this arti-
cle, I'll discuss remote-earth testing—
what it is, its significance, and why
you should consider incorporating
this practice when evaluating galvanic
CP  systems. Although remote-earth
testing is applicable to all galvanic CP

         C /?•'•'  u o
         * C  .   •  •-
systems, this discussion will be lim-
ited to the testing of sti-P3 tanks. To
help the reader better understand the
seemingly mystical science of cathodic
protection, I'll also discuss factors that
influence CP testing.

Reference Cell Placement
While it is important to realize that
many factors must be  considered
when testing the structure-to-soil
potential of a cathodically protected
tank, reference cell placement is of
critical importance. The basic idea is
that the reference cell must be placed
where it can "see" the tank. The con-
cept is analogous to a flashlight
beam—if the reference cell is placed
directly over the tank, the portion of
the tank that lies within the imagined
flashlight beam is the area of the aver-
age potential (voltage) measurement.
   The commonly accepted best
practice is to place the reference cell
in the soil directly over the centerline
of the tank being tested and as  far
away from any anodes as is practical
(Moreau, 1999). Measurement of the
cathodic protection with the refer-
ence cell placed directly above the
tank is referred to as the "close," or
more commonly, "local" potential.
   While it is desirable to provide
dedicated access  ports or test sta-
tions, practical considerations usually
dictate that  the  reference cell is
placed wherever soil access is avail-
able above the tank. This means that
the reference cell is usually placed
within the submersible-pump man-
way or some other existing opening
through the pavement.
   It is critically important that the
reference cell be placed in the soil
and never on top of the concrete or
asphalt when measuring  the tank
potential (NACE, 2001). If there is no
access to  the soil, holes  must be
drilled through the pavement in
order to conduct a valid test. Testing
with the reference cell placed on the
pavement will usually introduce sig-
nificant errors.
   Unfortunately,  the  commonly
accepted best practice is not always
followed by CP testers, and the refer-
ence cell is more  typically placed
practically anywhere that will yield
the desired result  (a "pass" or a
"fail," depending on the objectives of
the person conducting  the test).
Given this "anything goes" scenario,
reference cell placement has ranged
from the soil over the tank to the
flower bed across the parking lot to
the drainage ditch behind the store
building and everywhere in between.

                                                                                November 2004 • LUSTLine Bulletin 48
Local Reference Cell
When obtaining the local potential,
only a relatively small portion of the
top of the tank is measured. There-
fore, it has become common practice
to place the reference cell at three
points along the top of the tank (each
end and the middle) in an effort to
measure as much of the tank as possi-
ble (Moreau,  1999). Because local
measurements look at specific areas
of the tank, an area that is not receiv-
ing  adequate  cathodic  protection
may be identified. However, since
only the top portion of the tank is
measured,  local potentials tell you
nothing about the degree of cathodic
protection along the bottom half of
the tank.
    Portions of the tank other than
the top may be evaluated by conduct-
ing   potential  profiling,   which
involves the drilling of holes in close
proximity to the tank so that the ref-
erence cell may be placed at various
depths, allowing measurement of the
potential from ground level to below
the bottom of the tank (NACE, 2002).
Unfortunately, it is not usually prac-
tical to  perform potential profiling
since drilling is required  and few
tank facilities have such an arrange-
ment of test holes installed.
    Permanent reference cells buried
at the time the tank is installed may
allow you to measure the tank poten-
tial at locations other than the top of
the tank. However, in order to inter-
pret the test results properly, it is crit-
ical that  the exact   depth  and
orientation of the  permanent refer-
ence cell relative to the tank is care-
fully  documented.  Although  a
number of sti-P3 tanks were installed
with permanent reference cells (PP4
test stations), the exact burial location
of the reference cell was often not
adequately documented.
    If the location of the reference cell
is not known with a high degree of
certainty, such potential measure-
ments are of little value, since the cell
could have been buried in close prox-
imity to one of the tank anodes. If the
reference cell is in close proximity to
an anode, the structure-to-soil poten-
tial  measurement  is likely to be
higher (more negative) than it really
should be because the measurement
will be influenced by the voltage gra-
dient of the active anode, (See the
"raised-earth" discussion below.)
    Although only the top of the tank
is usually tested, conventional wis-
dom is that it is reasonable to assume
that the top portion of the tank would
be the most difficult to protect with
sti-P3 tanks since this area is farthest
away from the anodes. While this is a
logical assumption,  it may be pru-
dent to keep in mind  that most corro-
sion failures seem to  occur along the
bottom of the tank.  One of the rea-
sons that the factory-installed anodes
are attached near the  bottom of sti-P3
tanks is to help protect the more sus-
ceptible tank bottom.
   While it is important to realize that
   many factors must be considered
   when testing the structure-to-soil
  potential of a cathodically protected
  tank, reference cell placement is of
   critical importance. The basic idea
   is that the reference cell must be
  placed where it can "see" the tank.
Determining "True" Local
Factors that complicate our ability to
obtain accurate ("true") local poten-
tials must be considered when evalu-
ating  the  significance  of  such
measurements. Local potentials may
be subject to interference or "shield-
ing" from various sources at a typical
tank facility (Peabody, 2001). Shield-
ing prevents or otherwise interferes
with the current reaching the refer-
ence cell as it normally would if there
were no interference.  In the absence
of other  readily apparent explana-
tions, shielding is commonly cited as
the reason for substandard CP read-
ings when the reference cell is placed
locally (STI, 2001a).
    Given that there may be numer-
ous "foreign" metallic  structures pre-
sent  (e.g.  the submersible  pump
head, metallic product piping, electri-
cal conduits,  tank risers), it seems
reasonable that these structures could
interfere with obtaining local poten-
tials.  However, there are differing
opinions  regarding the validity of the
concept  of reference-cell shielding
caused by electrically isolated tank
appurtenances. Accordingly, caution
should be exercised whenever shield-
ing is cited as the cause of substan-
dard cathodic protection readings.
Further testing or evaluation may be
necessary by a person qualified as a
"corrosion expert" to better deter-
mine the "true" cathodic protection
status of the tank.
    In  addition  to  shielding, local
potentials may also be influenced by
the effect of  "raised earth," a term
used to describe the voltage gradient
that is present in the soil near an
active anode (NACE, 2001). If there
are active anodes in proximity to the
reference cell, the potential measured
on  the  protected  structure  will
appear to be higher (more negative)
than it actually is. The potential will
appear erroneously high (more nega-
tive), since the measurement includes
the voltage drop induced by the volt-
age gradient  of the active anode.
Because of the raised-earth effect it is
possible for the tank to appear well
protected when it may, in fact, not be
protected at all.
    While not typically a significant
concern on well-coated tanks that
have   only   factory-attached   zinc
anodes, raised earth can have a sub-
stantial effect on  those tanks that
have had magnesium anodes retrofit-
ted or buried nearby. It is not uncom-
mon to  have magnesium anodes
buried  within  the  submersible-
turbine manway in an effort to pro-
tect metallic piping. In  these cases,
the reference cell must not be placed
within the submersible turbine man-
    If the structure-to-soil potential
of the tank is measured at the sub-
mersible-pump  manway,  the  ob-
served potential will be higher (more
negative) than it really is since it will
include the voltage drop caused by
the current output of the magnesium
anode. Depending on the soil resis-
tivity and the amount of current pro-
duced by the anodes, it may not be
possible  to place the reference cell
locally such that the observed poten-
tial is not influenced by the voltage
gradient of an active anode.
    Other metallic  structures  com-
monly found in the tank  environ-
ment described above that can have
an influence on the observed poten-
tial include the galvanized skirts pre-
sent on most manways. Although the
                • continued on page 30


LUSTLine Bulletin 48 • November 2004
• Remote-
Earth Testing
from page 29

voltage drop pro-
duced  by  these
skirts  is  not as
pronounced  as
with magnesium
anodes, the zinc
coating of the gal-
vanized skirt may
also  cause  the
observed     tank
potential   to  be
higher (more neg-
ative) than it actu-
ally   is.    The
magnitude of the
error that will be
caused  by  this
voltage drop depends largely on the
proximity of the reference cell to the
skirt and the condition of the galva-
nized metal. Figure 1 is a field exam-
ple of a series of measurements made
within  the  submersible-turbine-
pump manway of a sti-P3 tank. The
tank in this example has substandard
CP that continuity testing indicates is
caused by a short between the tank
and the fill riser.
    The manway in this example is
filled nearly to grade with sand back-
fill, a common practice when contain-
ment sumps  are  not present.  The
manway is a typical 2' x 2' steel man-
way with a 10 inch galvanized steel
skirt. A potential measurement of
-730 mV was observed with the ref-
erence cell placed at grade level in the
soil within the manway. Grade level
in this example placed the tip of the
reference cell approximately 35"from
the top of the tank and 6 " up inside
the metallic skirt (measurement point
P-l). The soil was then excavated
approximately 7"  placing the tip of
the reference cell 1" below the bottom
of the manway skirt and a potential
of -658 mV was obtained (P-2).
    If the "true" potential of this tank
is  -658 mV (the  remote potential of
this tank was -656 mV), the galva-
nized skirt of the manway has appar-
ently caused the tank potential to be
72 mV higher (more negative) than it
actually is.
    As can also be seen from the data
in Figure 1, soil resistivity may also
influence  the observed potential. If
you assume the "true" potential of
the tank as  it would normally be

Figure 1 Potential Measurements Above the Tank
Submersible Turbine
Pump Manway Concrete pgd



— p-1 |&^^$££$S3£&

= p-2 rr"1
-7 p-3 ;
- P-4W-
i P.^S
^ P-5 : >
-i p. 6^^
• •
^*>~ Galvanized Ski

Sand Backfill
^ Measurement Poin $
• 	 - ' ' •



Measurement Distance Observed
Point Above Tank Potential

P-1 35 inches -730 mV
P-2 28 inches -658 mV
P - 3 24 inches -608 mV
P-4 18 inches -600 mV
P-5 12 inches -594 mV
P - 6 6 inches -580 mV
P - 7 1 inch -565 mV
Remote Earth = -656 mV

measured is -658 mV, it can be seen
that the voltage difference between
measurement points P-2 and P-7 is
103 mV. It is likely that this difference
is caused by the voltage drop present
in the soil column between the tank
and the reference cell. Although the
amount of error caused by this volt-
age drop is  normally disregarded
because the -850 mV criterion is con-
sidered to compensate for this error
(Peabody, 2001), it  is something  to
keep in mind when evaluating test
    Another problem sometimes pre-
sented by soil resistivity characteris-
tics can be seen in cases where a layer
of very high-resistivity soil is present
above  the tank. Consider the case
where  a tank is buried in sand back-
fill, but the top of the excavation is
filled to grade with pea gravel. In this
situation, it would be very difficult to
measure adequate CP with the refer-
ence cell placed on
top of  the backfill,
as   it   typically
would  be   when
obtaining the local
potential. The tank
would  appear to be
completely unpro-
tected   when   it
could  actually be
very well protected
along the most sus-
ceptible   (bottom)
portion of the tank.
    Contact  resis-
tance  between  the
reference cell and
the tank backfill,
material is another factor that some-
times makes it difficult to obtain
accurate local potentials. Although
contact resistance is normally com-
pensated for by the use of voltmeters
with  very  high (10 megohm or
greater) input resistance, it can be
troublesome when the backfill mater-
ial  is very  dry or is  of  crushed
stone/pea gravel composition. Water
is usually added to the soil at the
point of contact with the reference
cell in an effort to minimize contact
resistance. Additionally, petroleum-
contaminated or frozen  soils can
cause a high contact r esistance and
should be avoided whenever testing
CP (Moreau, 1996).

Local Variability
A rather large degree of variability is
seemingly inherent in local potentials
even when there are no apparent rea-
sons for it.  It is not uncommon to
Fi9ure2 Local Variability

4= 945 m V K = 819mV
1 v = 974 mV I- = 974 mV
C = 973 mV G = 978 mV


972 mV



                                                                               November 2004  • LUSTLine Bulletin 48
observe a substantial variation in the
potential just by moving the refer-
ence cell around a few inches this
way or that. Figure 2 depicts the test
data obtained by a MDEQ inspector
and illustrates very clearly the vari-
ability  that can  be  seen  when
attempting  to  measure the  local
potential. The variation within the 2'
x 2' manway near the center of the
tank  (where  the  automatic  tank
gauge probe is  installed) shows a
variation of 159 mV in the potential,
depending on where the reference
cell is  placed within the manway. The
same  variability can be seen within
the manway of the submersible-tur-
bine pump, although here it is only
42 mV. All  of these measurements
were made with the tip of the refer-
ence cell placed below the bottom of
the manway skirts in order to remove
any influence they may have.
    Are these differences in the tank
potential real, or is this just an artifact
of measurement difficulties  inherent
in the environment above the tank?
Are the readings being shielded by
metallic tank appurtenances in the
congested above-tank environment?
Is there an anode buried somewhere
within or  near the manways that is
affecting the readings? Should the
test for this tank be declared a "fail"
since the potential at test point "E" is
-819 mV?  Given that the reasons for
this variability are not well under-
stood, can the remote-earth potential
help us decide what the most logical
answers to  these questions should

Remote  Earth
Another way to measure the struc-
ture-to-soil potential is to place the
reference cell some distance away (or
remote) from the tank. By doing this,
the factors discussed above that can
make  obtaining local potentials prob-
lematic may be mitigated. The struc-
ture-to-soil potential that is measured
at remote  earth can be thought of as
representing the average potential of
the entire tank shell. Remote earth is
achieved when the structure-to-soil
potential of a buried metallic struc-
ture remains constant, irrespective of
how far away or in what direction the
reference cell is placed.
    It is generally accepted that the
reference cell must be at least 25-30
feet away  from a sti-P3 tank in order
to achieve a remote-earth condition
(STI, 2000). Under normal conditions,
this distance is sufficient to place the
reference cell outside the area of
influence generated by the voltage
gradient of an active anode. Since a
volume of soil has a finite resistance
(STI, 2000), the potential will remain
essentially the same no matter how
far away or in what direction the ref-
erence cell is placed once  remote
earth has been achieved.
    Placing   the   reference   cell
remotely   accomplishes   several
things, including:
  •  Minimizing   the   raised-earth
    effect voltage gradients of active
    anodes  may  impart  on  the
    observed potential.

  •  Minimizing   the   "shielding"
    effect  tank-top appurtenances
    may have on the observed poten-

  •  Mitigating the error imparted by
    high-contact resistance between
    the reference cell and the tank
    backfill materials.

  •  Providing the average potential
    over the entire tank, the only
    practical way to "see" the bottom
    of the tank.

  •  All things being equal, making
    the test results  generally more
    reproducible than those obtained
    with the reference  cell placed
    locally. This is because it is usu-
    ally not known exactly where the
    reference  cell  was  placed to
    obtain the local potential and, as
    long as  remote earth has been
    established,  it does not matter
    where the reference cell is placed
    to obtain the remote potential.

Determining "True" Remote
An important aspect of remote place-
ment is the need to establish that a
"true" remote-earth condition has
been achieved. In the simplest sce-
nario, remote earth is established by
placing the reference cell in the soil a
certain distance away from the pro-
tected  structure  and measuring the
potential. The reference cell is then
moved out away from the protected
structure an additional ten feet, and
the potential is again measured. This
process is repeated  until there is no
appreciable difference between two
potential measurements. When there
is  no difference  between  the two
potentials, it can be assumed that
remote earth has been achieved.
    Factors that can complicate the
establishment of  true remote  earth
must  also  be  considered  when
attempting to measure the remote
potential. For example:
 •  The reference cell should not be
    placed in proximity to any other
    cathodically protected structures,
    such as natural gas pipelines.

 •  Chain-link fencing, commonly
    found at UST facilities,  is galva-
    nized, and the reference cell must
    not be placed near it since the
    raised earth produced by the zinc
    in  the galvanized coating can
    influence the observed potential.

 •  Since any buried metallic struc-
    tures (e.g., water lines, electrical
    conduits,  other utilities)  can
    influence the remote potential,
    the reference  cell must also not
    be  placed  over these structures
    (Peabody, 2001).

 •  It is better if any buried metallic
    structures are not  between the
    reference cell and the protected
    structure, although this  is gener-
    ally not a significant factor.
    Given that there is usually lim-
ited access to soil at locations that are
remote from the tank, and there are
other buried structures to  contend
with, it is often necessary to move the
reference cell to several different
locations around  the facility and at
varying distances away from the tank
before  it can be comfortably estab-
lished  that remote  earth has been
achieved. Only when the potential is
essentially the same at two or more
locations that are remote from the
tank can it be  assumed that remote
earth has been achieved.

Remote vs. Local
Placing the reference cell remotely
measures the average potential of the
entire tank. Placing the  reference cell
locally measures the average poten-
tial of a small area on the top of the
tank. Although local measurements
can give you  information  about a
specific area of the tank, it  is some-
times problematic to be sure that the
local measurement is representative,

                • continued on page 32


 LUSTLine Bulletin 48 • November 2004
• Remote-Earth Testing
from page 31

 and it may be difficult to reproduce
 the  test results. With remote mea-
 surements,  it is normally easier to
 mitigate  environmental influences
 and to reproduce the test results. The
 ability of a person to reproduce the
 results that someone else obtained
 during a previous  test is  a very
 important and desirable aspect of CP
     Remote measurements do not tell
 you anything about a specific area of
 the tank, and it is possible to have an
 area of the tank that is not protected
 and still have a "passing" remote
 potential. Similarly, local potentials
 (measured at the top of the tank) do
 not tell you anything about the lower
 portion of the tank, and it is possible
 to have an area of the tank that is not
 protected and still have a "passing"
 local potential.
     Referring back to Figure 2, can
 the  remote-earth potential help us
 decide which potential best repre-
 sents the "true" local potential? Con-
 sidering that the remote potential of
 the tank in Figure 2 is 972 mV and all
 of the local  measurements  (except
 test point "E") are well above -900
 mV, it would seem reasonable to con-
 clude that  the -819 mV potential
 observed at point "E" is not represen-
 tative and should probably be  disre-
 garded. The remote potential can
 sometimes help you decide what is
 the most representative local poten-
 tial  in those cases where it is not
 clearly evident.

 MDEQ Testing Requirements
 In the State of Mississippi, the refer-
 ence cell must be placed both locally
 and remotely when conducting a test
 of a galvanic CP system. In order for
 the test to "pass," both the local and
 the remote potential must be -850mV
 or higher (more negative). The test
 result is declared a "fail" if both the
 local and the remote are lower  (more
 positive) than -850 mV. If one  of the
 potentials is -850 mV or higher but
 the other is not, the test is considered
 to be "inconclusive." (See Table 1.)
 With inconclusive results, the CP sys-
 tem must be modified/ repaired or
 evaluated by a "corrosion expert,"
 who may evaluate the data or con-
 duct further testing  in order  to
 declare either a pass or fail of the test.

TABLE1 "Making the Call"
-850 mV or higher
lower than -850 mV
-850 mV or higher
lower than -850 mV
-850 mV or higher
lower than -850 mV
lower than -850 mV
-850 mV or higher
    When obtaining the local poten-
tial, the reference cell can be placed
anywhere along the centerline of the
tank but not directly over the ends.
Since the remote potential  is also
required,  it was decided that only
one local measurement of the poten-
tial directly over the tank would be
required.  Ideally, if  only one local
potential is measured, it should be
obtained from the center of the tank.
If the anodes located at both ends of
the tank are functioning, the center of
the tank  should have  the  lowest
potential,   since
this is the area of
the   tank   that
would be the far-
thest away from
the anodes.
    With only one
local    measure-
ment, it is possible
that the  anodes
could   be  com-
pletely  depleted
on one end of the
tank and this con-
dition would not
be    recognized.
While possible, it
seems reasonable that such a condi-
tion would usually  be  recognized
when the MDEQ testing guidelines
are followed, since the remote poten-
tial would likely be too low and the
test result would be inconclusive.

MDEQ Findings
From July 2002 through March 2004,
MDEQ inspectors measured the CP
on  1,037  sti-P3  tanks  as  part  of
routine  compliance  inspections.
Structure-to-soil potential measure-
ments were obtained both locally and
remotely on all of the tanks that were
included in the data set for this study.
The tanks measured ranged in size
from 500 to 20,000 gallons and were
installed from 1985 through 2002. No
attempt was made to identify tanks
that had been retrofitted with supple-
mental anodes at the time the testing
                 was conducted.
                    The  results  of  the  testing
                 revealed that 83 percent of the tanks
                 fully passed the evaluation. Of the
                 tanks that did not pass the evalua-
                 tion, 12 percent failed and 5 percent
                 were inconclusive. (See  Figure 3.)
                 This means that in only 5 percent of
                 the cases was there any discrepancy
                 between the  local and the remote
                 potential with respect to the pass/fail
                 status of the tanks. Of the tanks that
                 were inconclusive, 53 percent passed
                 the remote but  failed the local and
               MDEQ Test Results
     83% (858) Passed
     12% (122) Failed

     5% (57) Inconclusive
                 47 percent failed the remote while
                 passing the local.
                    The MDEQ testing data indicate
                 that the remote potential is just as
                 likely to indicate a "fail" as it is a
                 "pass" when there is a discrepancy
                 between the local and the remote
                 potentials of sti-P3 tanks. In only 3
                 percent of the cases where there is a
                 discrepancy between the local and
                 the remote does the remote indicate
                 that the tank is protected when the
                 local does not.
                    In comparing the local to  the
                 remote potential (without consider-
                 ing the pass/fail status), the local was
                 essentially the same as the remote for
                 15 percent of the tanks. (See Figure 4.)
                 The local was found  to be higher
                 (more negative) than the remote 42
                 percent of the time. While there are a
                 number of factors that could cause

                                                                                     November 2004  • LUSTLine Bulletin 48
  Figure 4
                  Local vs. Remote
      1037 TANKS TESTED

      • 15% (151) Remote = Local
          (difference-::: 10 mV)

      42% (432) Remold :: Local
       (average 79 mV difference)

      43% (454) Remote ••• Local
       (average 80 mV difference)
this difference, the voltage gradient
caused by active anodes in the soil
near the tank (raised earth) is one
possible explanation. The local poten-
tial was found to be lower (more pos-
itive) than the remote potential on the
remaining 43 percent of the tanks. In
the absence of other readily apparent
reasons, shielding of the reference
cell in the congested above-tank envi-
ronment is the most logical explana-
tion for this difference.
    When a difference is measured
between the local  and the  remote
                  suring sti-P3 tanks
                  and that  differ-
                  ence is +/-80 mV.

                  At the End of
                  the Day
                  Although this dis-
                  cussion has been
                  limited to  sti-P3
                  tanks,     remote-
                  earth  testing  is
                  equally applicable
                  to most galvanic
                  (sacrificial anode)
                  CP   systems.  Of
                  the  1,037  tanks
                  tested  by MDEQ,
the average local potential was -964
mV and the average remote potential
was -962 mV. While  it  sometimes
seems that the only thing certain with
CP is that there are no certainties, the
data would suggest that the remote
potential is a valuable tool. Given the
inherent advantages  of  measuring
remote potentials (see Table 2), it
would seem prudent to incorporate
remote-earth testing when evaluating
galvanic CP systems.
    In addition to  Mississippi, the
states of Georgia, Kentucky,  North
TABLE 2 Advantages of Local/Remote Reference Cell Placement

Ease of obtaining (soil access)
Reproducibility (between different testers)
Variability (no change if reference cell moved)
Shielding (from tank appurtenances)
Shielding (from other metallic structures)
Raised earth (voltage gradient of anodes)
Contact resistance (between cell & soil)
Measures specific area of tank
Measures entire tank
Overall cathodic protection status of tank





potentials, how much is it? In the
cases where  the local  was higher
(more negative) than the remote, the
average difference between the two
was 80 mV. In cases where the local
potential was lower (more positive)
than the remote potential, the aver-
age  difference  was  79  mV. The
remote is just as likely to be lower
(more positive) as it is higher (more
negative) than the local is when mea-
Carolina, and South Carolina also
have policies that require testing of
galvanic CP systems remotely. There
are several other states that are in the
process of adopting similar CP test-
ing  requirements.  The Steel Tank
Institute describes the use of remote
earth testing for sti-P3 tanks (STI,
2001a). NACE International  also rec-
ognizes that remote-earth placement
of the reference cell can be an accept-
able alternative and is useful when
determining the significance of volt-
age drops (NACE, 2001).
    While the data would suggest
that the remote-earth potential by
itself on a well-coated tank could be
reliable, we will continue to require
that both the remote and the local
potentials be measured. We believe
that each has its own distinct advan-
tages/disadvantages.  The remote
measurement tells  you the overall
condition of the tank while the local
helps to identify specific areas of the
tank that may not be protected. Both
measurement techniques should be
utilized in conjunction  with each
other in order to evaluate galvanic
cathodic  protection systems  in the
best manner possible. •

  Kevin S.  Henderson, P.G., is Compli-
 ance and Enforcement Manager for the
  Underground Storage Tank Branch,
  Mississippi Department of Environ-
  mental Quality. He can be reached at

  To Learn About CP Basics: Check
   out LUSTLine #23, "Rust Thou
     Art and to Rust Thou Shalt
  Return," and LUSTLine #25, "Is
       This Tank Cathodically

MDEQ, 2002, Guidelines for the evaluation of under-
 ground storage tank cathodic protection systems,
 Mississippi Department of Environmental Quality,
 Jackson, MS.
Moreau, Marcel, 1995, Testing cathodic protection
 systems, LUSTLine Bulletin #25.
Moreau, Marcel, 1999, Combating CP-test heartburn,
 LUSTLine Bulletin #32.
NACE, 2001, TM0101-2001, Standard test method,
 measurement techniques related  to criteria for
 cathodic protection on underground or submerged
 metallic tank systems", NACE International, Hous-
 ton, TX.
NACE, 2002, RP0285-2002, Standard Recommended
 Practice, Corrosion control of underground atorage
 rank aystems by xathodic protection", NACE Inter-
 national, Houston, TX.
Peabody, A.W., 2001, Peabody's xontrol of pipeline
 corrosion, NACE International, Houston, TX
STI, 2000, Consideration of extraneous voltage cCom-
 ponents in tank-to-soil potentials obtained for
 cathodic protection monitoring of sti-P3 Tanks",
 Steel Tank Institute, Lake Zurich, IL.
STI, 2001a, TankTalk Newsletter, Vol. 16, Number 2,
 Ask the expert - CP tests for sti-P3 Ttanks, Steel
 Tank Institute, Lake Zurich, IL.
STI, 2001b, Recommended practice for the addition of
 supplemental anodes to sti-P3 USTs", Steel Tank
 Institute, Lake Zurich, IL.

LUSTLine Bulletin 48 • November 2004
MtBE Problems Set the  Stage
for  New UST Regs  in Maryland
       Over the last several years, the
       Maryland the Department of
       the Environment (MDE) has
seen an increase of groundwater
cases that involve MtBE. Since 1998
MDE has found that close to 600 pri-
vate wells have been impacted with
MtBE at 5 ppb or higher across the
state. Public well impact data show
similar locational trends. The largest
impacts appear to be across the top of
the state in areas with fractured-rock
geology. These areas include Har-
ford, Cecil, Carroll, Baltimore, and
Frederick Counties.
    Early on, MDE technical staff felt
that a contributor to the MtBE prob-
lem at these stations was the enriched
MtBE vapors being released into the
storage tank backfill from systems
that utilize Stage II vacuum-assist
vapor recovery under  continuous
    In response to these events, the
governor has ordered MDE to write
emergency technical regulations that
will require early detection and better
containment of MtBE in UST systems
in the state's High Risk Groundwater
Use Areas. All UST construction, con-
tainment, and leak detections regula-
tions, to date, have focused on liquid
releases, not vapor. The revised regu-
lations are in the review process and
are expected to  be promulgated in
January. Further details can be found
on MDE's Web  site  at:  www.mde. We'll provide up-to-date
details   in  the next   issue  of
   August 1985/Bullettn #1 - November 2OO4/Bullettn #48
   The NEW LUSTLine
   Index—the long and
   action-packed story of
   USTs and LUSTs—is
   ONLY available online.

   To download the
   LUSTLine Index, go to
   line.htm, and then click
   on LUSTLine Index.
                The Brownfields Bear
  Oakland, California USTfields Pilot Wins Phoenix Award
  The winners of the 2004 Phoenix Awards were announced on July 22, and
  the City of Oakland/Habitat for Humanity housing project was a Commu-
  nity Impact Award winner. This is one of only three such community
  awards nationwide. In all, 14 brownfields projects were honored for meet-
  ing the environmental challenge of transforming abandoned brownfields
  into productive new uses. In Oakland, an old petroleum-contaminated gas
  station was cleaned up, and four new single-family homes housing 13 peo-
  ple were built on the site. The project was the recipient of a 2000 USTfields
  Pilot grant.  Phoenix Award winners were formally recognized at the
  Brownfields Conference in September.

  New Federal ATF Building to Stand on Old LUST Site in DC
  An old LUST site undergoing remediation in  the northeast section of the
  District of Columbia is slated to become the new national headquarters of
  the federal Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF).
  Five USTs were removed from the site in 1991, and the presence of petro-
  leum hydrocarbons and other contaminants was discovered over much of
  the area. A remediation system is in place, and the DC UST program is
  working with the U.S. Government Services Agency to clean up and pre-
  pare the site for construction. The building planned for the site will house
  approximately 1,100 ATF personnel and is expected to open in 2005. •
Shell Oil U.S./Motiva to
Phase Out MtBE in

    Shell  Oil  Products U.S. and
    Motiva Enterprises, LLC are
    working  toward  substantially
reducing and ultimately phasing out
the use of MtBE in the gasoline the
companies manufacture and sell in
the United States. Shell Oil Products
U.S.  no longer manufactures  or
blends MtBE into gasoline produced
at its four West Coast refineries, and
Motiva has decided to cease blend-
ing MtBE into products it manufac-
tures at two terminals in Louisiana.
Combined, these two terminals dis-
tribute more than 430 million gallons
of gasoline   per  year.  Also,  in
response to Connecticut and New
York MtBE bans, Motiva constructed
and operates an ethanol import and
blending facility at its terminal in
Sewaren, New Jersey.
   The companies  are looking for
other markets where they might be
able to phase out the use of MtBE in
their gasoline, consistent with federal
fuel requirements, state legislation
and regulation,  market conditions,
and the gasoline distribution system
in that part of the country. The com-
panies are responding to legislators
and regulators who are asking that
they remove MtBE from gasoline. To
date, more than 20 states have or are
considering a ban of MtBE. The com-
panies say a complete phaseout will
only occur if there is a change in cur-
rent regulatory requirements. •
                                     LUSTLine T-Shirts
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                                                                            November 2004 • LUSTLine Bulletin 48
ASTM Microbiology Work Group Seeks Data on
FRP Deterioration

I was delighted to read Mr. Roggelin's LUSTLine #47 article, "Pipes and
Sumps—As I See Them," on the biodeterioration of non-metallic piping. The
phenomena that Mr. Roggelin discusses are not limited to piping. Unfortu-
nately, most industry stakeholders with direct knowledge of failed fiber rein-
forced plastic (FRP) UST features are restrained from sharing that knowledge
in open forums like LUSTLine. Mr. Roggelin was able to write a pithy article
shedding much-needed light on this underdiscussed problem. My hat is off to
him for a job well done.
   I also encourage industry stakeholders with photos and other specific
data about FRP biodeterioration to share it, either in LUSTLine or at ASTM
Subcommittee D.02.14 Fuel Microbiology Working Group meetings. We can't
solve industry problems or develop best practices for problem prevention as
long as the affected folks pretend that denial is an effective prevention tool.
The next ASTM D.02  meeting will be on December 5-9, 2004, in Tampa,
Florida. Guests are always welcome at these meetings. People can get meeting
details at ASTM's Web site: Once at the Web site, click on
"Meetings," "List of ASTM Future Meetings", and "Next 12 Months," then
scroll down to "D02 Petroleum Products." •

   Frederick J. Passman, Ph.D.
   Chair, ASTM D.02.14 Fuel Microbiology Working Group
New Jersey Initiates an
Enhanced Statewide  UST
Compliance Inspection

   In August, New Jersey Department
   of   Environmental   Protection
   (NJDEP)  Commissioner Bradley
Campbell announced the start of  a
new, enhanced statewide UST com-
pliance inspection program. NJDEP
is establishing a group of 18 state and
county inspectors to conduct compli-
ance inspections at each UST facility
once every three years. In past years,
state UST inspections were conducted
on the basis of complaints or referrals.
"Millions of New Jersey residents get
their drinking water from aquifers
that are vulnerable to pollution from
leaking tanks. New Jersey was long
overdue  for a more  effective leak-
prevention program for underground
tanks, but this has changed with the
state making new funding available,"
said Campbell.  In 2003, New Jersey
voters overwhelmingly approved  a
public referendum to provide NJDEP
a stable funding source for its UST
inspection program.  The complete
news   release  can  be   seen at
rel/2004/04_0096.htm. •
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          Phone: (978) 323-7929 • Fax: (978)  323-7919


 FAQs  from  the  NWGLDE
 .. .All you ever wanted to know about leak detection, but were afraid to ask.
 GueSS What? With this issue of LUSTLine we are
 launching a new section called "FAQs from the
 NWGLDE" by the National Work Group on Leak
 Detection Evaluation, an independent work group
 comprised of 10 members—eight representing various
 states and two from the U.S. EPA. The Work Group plans
 to publish the answers to frequent questions they receive
 from regulators and people in the industry on leak
 detection. If you have questions for the group, please
 contact them at . (Please note: the
 views expressed in this column represent those of the
 work group and do not necessarily represent those of any
 implementing agency.)

 FYI, the mission of the NWGLDE is  to:
  •  Review leak detection system third-party evaluations
     to determine  if each evaluation was performed in
     accordance with an acceptable leak-detection test
     method protocol and ensure that the leak-detection
     system meets EPA and/or other applicable regula-
     tory performance standards

  •  Review only draft and final leak-detection test
     method protocols submitted to the work group by a
     peer review committee to ensure they meet equiva-
     lency standards stated in the U.S. EPA standard test

  •  Make the results of such reviews available to inter-
     ested parties

 Can ELLDs Be Used as a Line-Tightness Test Method?

   Q  Companies such as Veeder-Root and INCON are
       marketing their electronic line leak detectors
       (ELLDs) to the regulated community as Line-
       Tightness Test Methods, in addition to meeting
       the line leak-detector criteria. Under the specs for
       each ELLD, the llth edition, 2004, List Of Leak
Detection Evaluations For Storage Tank Systems
shows that a O.lgph test is possible, but does not
specify its equivalence to a line-tightness test.
However, the NWGLDE listing for Line-Tight-
ness Test Methods  does not list any ELLDs as
being acceptable as a Line-Tightness Test Method
(pg. 13, llth edition  of the List). So, my questions
are: (1) Are there any ELLDs that can do a line-
tightness test? (2) If so, where can I find that list?

You are  right, ELLDs are not  listed by the
NWGLDE under Line-Tightness Test Methods.
However, many, but not all, of them were third-
party tested at the  O.lgph leak rate under the
same range of environmental and pipeline config-
uration conditions that are used to test systems
that conduct monthly monitoring and line-tight-
ness tests. The performance of the ELLD during
third-party  testing is  documented  on  the
NWGLDE List data sheet for the equipment.

If the ELLD has sufficient performance character-
istics, it can be used  to satisfy the monthly moni-
toring test or annual line-test requirements. The
leak rate of O.lgph is an equivalent leak rate at a
lesser pressure, since the ELLD does not typically
test the piping at one and one-half times the oper-
ating pressure. (See USEPA Standard Test Proce-
dures for Evaluating Leak Detection Methods:
Pipeline  Leak  Detection  Systems, September
1990.) The decision to accept or deny use of this
method remains with the implementing agency.

You can identify ELLDs that have an acceptable
third-party result at a O.lgph leak rate by looking
at the method summary page for Automatic Elec-
tronic Line Leak Detectors at
tronic_lld.html. •
New England Interstate Water
Pollution Control Commission
Boott Mills South
100 Foot of John Street
Lowell, MA 01852-1124