United States
                            Environmental Protection
                            Agency
                                                             Solid  Waste and
                                                             Emergency Response
                                                             (SKEW)
                                 EPA-542-N-94-007
                                 September 1994
                           Ground  Water   Currents
                                        Developments in innovative ground water treatment
 UP-TO-DATE WAYS  TO  ASSESS  WHEN
 BIOREMEDIATION   WORKS
 Robert S. Kerr Environmental Research Laboratory
 Vvhen does  in situ           the current practice  for
bioremediation  work?  And,    characterizing  sites does  not
                             adequately  define  the
                     And,
how  can you  reliably predict
success? An  operational
definition for judging  success
of in  situ bioremediation at
field scale is  that it meet
regulatory goals  for ground
water  quality in a timely
fashion and at a predictable
cost. Further,  in situ  bio-
remediation  is judged  by its
capacity to continue  to meet
regulatory goals  for water
quality after  the active phase
of remediation is  complete.
There are two factors  to
address in  judging success.
First  bioremediation,  par-
ticularly innovative bio-
remediation  that uses  an
electron acceptor other than
oxygen, can  remove the
compounds  of regulatory
concern from the subsurface
while  leaving significant
amounts of oily-phase
hydrocarbons.  Second,  the
extent  of weathering of
residual oily-phase material
and the hydrologic envi-
ronment of the  residual have
a strong influence  on  the
potential for  ground water
contamination  after active
remediation  ceases. An
important issue  for deter-
mining short-term success
and long-term  protection is
one of laboratory  studies
versus  actual field conditions.
The problem posed is that
                             amount of contamination
                             subject to bioremediation.
                             As a result, laboratory  studies
                             which estimate the  re-
                             quirements at field  scale for
                             electron acceptors  and
                             mineral  nutrients for bio-
                             remediation,  and the time
                             required  for  remediation,
                             have  much uncertainty when
                             extrapolated to field scale.  In
                             contrast to laboratory  studies,
                             the extent of remediation
                             achieved at field scale is
                             influenced by dilution  of
                             compounds of regulatory
                             concern  in circulated water
                             and  partitioning  between
                             water and the residual  oil.
                               Part of the  problem  with
                             the transfer of laboratory
                             research to the field is  that
                             there are different levels of
                             inquiry in the laboratory and
                             in the  field. Laboratory
                             studies  deal with biochemical
                             or physiological processes
                             with  appropriate  controls to
                             ensure that only one mech-
                             anism is responsible for the
                             phenomena under study.
                             However,  during field-scale
                             implementation of  bioreme-
                             diation technology, several
                             processes operate con-
                             currently. They  may involve
                             several distinct  mechanisms  for
                             biological destruction of the
                             contaminant, as  well as
partitioning  of contaminants
to immobile phases, dilution
in ground water and vol-
atilization.  Therefore,  if
performance monitoring  is
limited to the concentrations
of nutrients  and  electron
acceptors, it  cannot  ensure
that  the  biological process
developed in  the laboratory
was  responsible  for contami-
nant removal at  full-scale
field conditions.  Exper-
imental controls  are  usually
unavailable  during full-scale
implementation of in situ
bioremediation because the
technology is applied
uniformly to  the contami-
nated area. So, how  do you
know whether it  was the
biological process developed
in the laboratory or  some-
thing else that reduced
contaminant  concentrations?
And, how do you know
whether  or not natural
biodegradation will prevent
the regeneration of a plume
of contaminated  ground
water  when  active
remediation  ceases?
  To  overcome  these prob-
lems,  the  appropriate equiva-
lent of  experimental controls
is  a  detailed characterization
of the site, the flow  of
remedial fluids  and the  flux
of amendments.  This
characterization  allows  an
assessment  of the  influence of
partitioning,  dilution or
volatilization on  remediation
and provides a basis  for
evaluating  the relative con-
tribution of bioremediation.
  Wells  have traditionally
been used  to characterize
sites. Ground water  mon-
itoring  wells alone  cannot
estimate  the  total contam-
inant mass subject to re-
mediation  within an order  of
magnitude.  Most plumes of
organic  contamination in
ground  water originate  from
spills of refined  petroleum
hydrocarbons, such as gasoline,
or chlorinated solvents, such as
trichloroethylene.
       (See Bioremediation Page 2)
           This Month in Currents
THIS  MONTH'S  CURRENTS  CONTAINS  VENDOR  AND
BULLETIN  BOARD  INFORMATION.
BIOREMEDIATION
CLEAN   UP  BULLETIN   BOARD
VENDOR   DATABASE   UPDATE
            Recycled/Recyclable • Printed with Vegetable Oil Based Inks on 100% Recycled Paper (50% Postconsumer) . Please recycle as newsprint

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GROUND  WATER   REMEDIATION   CLUES
By Gary  Turner,  Technology  Innovation Office,  EPA
jf you have not heard about,
or lately have not been on
the  EPA's Clean-Up
Information Bulletin  Board
System  (CLU-IN),  you  may
he missing out on  some new
information  and  new
features. In the past year,
CLU-IN  has  upgraded the
software; and, we are  still in
the  process  of implementing
new features  and  customizing
prompts.  As always,  CLU-
IN  still has three main
components  — Bulletins,
Files, Messages.
  Bulletins. The bulletins  are
short text files  that can be
read online while you are
connected to CLU-IN.
CLU-IN  has regularly
updated bulletins  containing
TECH  TRENDS  and
GROUND  WATER
CURRENTS articles,
FEDERAL  REGISTER
updates and  COMMERCE
BUSINESS  DAILY
announcements.  There  are
monthly  regulatory reports
from  EPAs  RCRA/
CERCLA/OUST/EPCRA
Hotline, as well as EPA
Office  of Solid Waste and
Emergency Response  training
course schedules,  an-
nouncements  of workshops,
meetings, publications and
databases.
  Files. The files  available  on
CLU-IN can be in  any
format,  including  databases,
publications,  graphics   files,
utilities  and spreadsheets.
Although these  files  cannot
be used  online,  they can be
downloaded and  used on  the
user's  own  computer.
Among the files  available  for
downloading on  CLU-IN  are
the Hazardous Waste
Superfund Database,  the
Risk  Reduction  Engineering
Laboratory  (RREL)
Treatability Database,  the
Hyperventilate program
from  the Office  of
Underground Storage  Tanks
(OUST)  and  many
publications from  the
Technology  Innovation
Office.
  Messages.  CLU-IN  also  has
an  electronic  mail  capability
that allows  users  to exchange
messages  with  individual
users  as  well as to leave
messages to all of the
approximately 4,000 CLU-
IN users to stimulate wider
discussion. Many users  use
this feature to  get advice
from  other users who have
expertise with  similar  site
conditions or  contaminants.
  In  addition to these
features that  have always
been  part of  CLU-IN, in the
near future we will be
implementing  a  major
overhaul of the user  interface
to improve  the  user-friendli-
ness  of CLU-IN. We will be
streamlining  the  Main  Menu
and  creating  sub-menus   so
that  it will be  easier to
maneuver within CLU-IN.
For  instance,  the bulletins
will be  sorted into a  main
bulletin  menu  and  submenus
to make it easier to find
bulletins on  a  given topic.
Users will still  be able to
search the  text of bulletins
for key words  and display all
bulletins that are  new since
the last time the user called
into   CLU-IN.
  We will  also be adding two
new  online  databases to
CLU-IN in the near future.
One  database will be a
calendar of upcoming
conferences,  meetings and
workshops on  hazardous
waste  remediation  that  users
will be able  to search by
conference date,  location  and
topic. The other database
will contain  information  on
training  courses  offered by
EPA.  Users  will be able to
search it by  topic to locate
available  training.
   Changes will be  taking
place  to  CLU-IN  content,
interface  and  features
throughout the fall. We  will
profile some of  these changes
in  more detail in future
articles.  We encourage  you
to  call into  CLU-IN and  try
it out. Users do not need to
pre-register — you  can
register and  choose  your  own
password  on your first  call.
   The dial-in  number for
accessing  CLU-IN is: 301-
589-8366 (up  to 9600  baud;
communications settings  are  8
data bits,  1 stop  bit  and no
parity).  EPA users  can  connect
to  CLU-IN  using EPA's X.25
network  without needing a
modem.  For more  informa-
tion about CLU-IN,  call the
 CLU-IN  Help  Line  at 301-
589-8368.
(Bwremetliation continued from page 1)
These  substances  enter  the
subsurface as  nonaqueous-
phase  oily liquids,  traveling
separately from  the ground
water.  Although wells have
been used to  define the
extent  of contamination  in
the subsurface  environment
through  measurement of  the
contaminants  in the  ground
water,  they cannot reliably
determine  the extent  of
contamination  by oily-phase
materials.  This  monitoring
deficit is  particularly  impor-
tant because,  as  long
as the oily-phase liquid  is
present in the subsurface,
it can act as a continuing
source of contamination.
Recent research  has  docu-
mented that  monitoring well
data  grossly underestimate
the  extent of contamination
and that there is a need for
site  characterization  tech-
niques  that  can  accurately
estimate  the  total mass  of
contaminants subject to
bioremediation.
  The appropriate rigorous
approach  to  characterize sites
should include  the  collection
and  analysis  of core  samples
to estimate  total  contaminant
mass  in  the  subsurface in
order to predict the  demand
for nutrients  and electron
acceptor  that must be met to
complete the remediation.
Then one can  use the rate
 of supply  of the  limiting
 requirement  to estimate
 the time required for the
 remediation.  With  core
 samples, it is recommended
 that  they  be subsampled
 and extracted in the field to
 preclude losses  to volatiliza-
 tion  and  biodegradation
 during shipping to  a lab-
 oratory. By  using inexpensive
 headspace  analyses  in
 conjunction  with field  core
        (See Bioremetlultwn Page 3)
                                                                                          Ground Water Currents

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                                               VENDOR  INFO
GROUND   WATER  TECHNOLOGIES
 IN VISITT DATABASE
By Linda  Fiedler,  Technology  Innovation  Office,  EPA
 Yhe  U.S.  Environmental      technologies,  including  201
Protection  Agency has          that are full-scale and
released VISITT 3.0,  the
latest update of its  database
on  new cleanup  technologies.
VISITT (Vendor Infor-
mation System  for  Inno-
vative  Treatment Tech-
nologies)  lists  current
information  on the
availability,  performance
and  cost  of  innovative
technologies  to remediate
contaminated waste sites.
VISITT now contains  data
on  277  innovative
commercially available.
  This update  includes  46
technologies which are
designed to  treat  ground
water in situ. They can be
grouped  into the  following
categories:  air sparging
(eight technologies);
bioremediation  (18
technologies);  chemical
treatment  (three  tech-
nologies);  dual  phase
extraction  (six technologies);
and  thermal enhancements
(11  technologies).  The
three chemical  treatment
technologies include:  surfac-
tant  solubilization;  fixation
of  metals  and  radionuclides
by  pH  and redox changes;
and dechlorination  of
organics  by redox  changes.
Thermal  enhancements
include radio frequency
heating,  electric resistive
heating  and steam  injection.
According to  the technology
vendors that  submitted  the
information, 35 of the in situ
ground  water technologies
are available  for  full-scale  use
and  the  remainder are  in  the
bench  or pilot scale.
   To order  VISITT 3.0
diskettes  and the  user  manual
and  to  become a  registered
user, provide  your name,
company, address, phone
number  and  diskette size
needed (3-1/2 inch or  5-1/4
inch) by mail to  U.S.  EPAJ
NCEPI,  P.O. Box 42419,
Cincinnati,   OH  45242-2419
or by FAX to 513-489-8695.
(Bioremediation continued from page 2)
samples,  results  from  a
limited  number  of expensive
core analyses can be extrapo-
lated  to  a  large number of
field  headspace analyses.
Headspace  analyses are
inexpensive and generate
data in real time, which also
allows the  screening  in-
formation to be  used  to
guide  decisions  about  depth
and location of subsequent
cores.
  When water  is circulated
through  an oily-phase  spill
during  bioremediation, the
concentration of regulated
compounds will drop
because  of  simple  dilution.
Simple  partitioning  theory
can be  used to  calculate the
distribution  of hydrocarbons
of  concern  between the
recirculating ground water
and the residual  oily-phase
materials.  Simple  ground
water models  can  estimate
the volume of water circu-
lated  through a  spill during
the in situ bioremediation by
predicting amended  ground
water flow paths from  an
infiltration gallery  (sited
above  the  spill) to recovery
wells.  This information  can
be  coupled with simple
partitioning theory  to
estimate  the  apparent
attenuation due to  dilution.
Simple  partitioning  theory  is
also used to  predict the
concentrations of hydrocar-
bons  that will  remain in
ground water  that will  be in
contact with  weathered oily-
phase  residual  that  frequently
remains  after  bioremediation.
The predictions give an
indication  as to whether the
plume will be regenerated.
  Seasonal variations  and
weathering can  cause plumes
to  actually move away from
monitoring wells,  to possibly
return at a later date.  Addi-
tionally,  pockets  of fine
textured oily-phase  material
may still contain high
concentrations  of con-
taminants  because  remedial
fluids tend  to  pass around
the  fine-textured  material.
To supplement data from
monitoring wells,  many
regulatory authorities require
measurement  of residual  oily-
phase material left after
bioremediation. However,
ground  water quality is
controlled  by  the  relative
concentration  of organic
contaminants in the weath-
ered oily-phase residual and
not  by the absolute amount of
weathered total petroleum
hydrocarbons.  The  relative
concentrations   of  organic
contaminants  can be used to
predict  the concentrations in
ground  water in contact with
the  oily-phase  residual  by
using Raoult's  law. The
solution  concentration  in
water should  be proportional
to the mole fraction of the
hydrocarbon in  the oily phase.
  The  issue  now  becomes
whether  any residual oily-
phase hydrocarbon is capable
of producing  a plume  of
contamination at concen-
trations that exceed the
cleanup goal. Mass transfer
effects  control  the  access of
residual organic  con-
taminants  to  moving  ground
water.  When active
remediation is stopped,  the
concentration of electron
acceptor  returns  to  ambient
conditions  in  the aquifer, and
the  hydraulic gradient
returns  to  the normal
condition.  As a  result,  the
residence time  of water  in  the
spill area is longer  than
during  active remediation;
and, the total  amount of
hydrocarbon transferred to
the water  is greater, although
the supply  of electron
acceptor  for  biological
destruction  of the  hydro-
carbon  is  less. Darcy's  law
can be  used to  estimate the
interstitial  flow  velocity  of
the ground water and its
residence time along the
flow path.  Under  proper
      (See  Bioremediation,  Page  4)
  Ground Water  Currents

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conditions,  natural  bio-
degradation  supported by
ambient  concentrations
of electron  acceptors and
mineral  nutrients may
destroy organic  contaminants
as fast as they escape from
the  oily-phase residual.
However, currently no
established  procedures  exist
for  determining  under
ambient conditions whether
the mass  transfer  of hydro-
carbons from oily residual
material  will  exceed the
supply of oxygen  or other
natural  electron  acceptors.
At the present state of
science, only long-term
monitoring  can  determine  if
natural  biodegradation  will
prevent the  regeneration of  a
plume of contaminated
ground water.
  An assessment of natural
hydrologic conditions  at
a site will be  necessary to
intelligently  locate  com-
pliance  monitoring wells and
determine an appropriate
schedule  of monitoring. An
understanding  is  required
of the average natural
hydraulic  gradient  and  the
hydraulic  conductivity  in  the
depth  interval containing
residual  hydrocarbon  in
order to  predict the  velocity
and  trajectory  of potential
plumes of contaminated
water.  Frequency of moni-
toring  can be adjusted  to
reflect  the expected time
required  for ground water to
travel through  the  area
containing residual  hydro-
carbon  to  the  point  of
compliance.
  The  summary of  research
findings discussed  above
draws heavily from, and  is
covered in more detail with
research references, in  a
National  Research Council
report;  the citation is:
IN SITU  BIOREM-
EDIATION; WHEN  DOES
IT WORK?,  National
Academy  Press,  Washington,
D.C.  1993.  This work was
supported  by the United
States Air  Force through
Interagency  Agreement
RW 57935 114  between  the
Armstrong  Laboratory
Environics Directorate (U.S.
Air Force)  and the U.S.
Environmental  Protection
Agency's (EPA) Robert S.
Kerr  Environmental Research
Laboratory  (RSKERL) and
EPA's Bioremediation Field
Initiative. It has not  been
subjected  to  EPA review  and
therefore  does  not  necessarily
reflect the views  of  the EPA,
and  no  official  endorsement
should be  inferred.
  For  more  information, see
the report referenced above
and/or  call John  Wilson at
RSKERL at 405-436-8632.
 To order additional copies of Ground Water Currents,  or  to  be included on the permanent mailing list, send a fax request to the
                    National  Center for  Environmental  Publications and  information  (NCEPI) at  513-489-8695.
                                       or send a mail request to NCEPI, P.O. Box 424 19
              Cincinnati,  OH 45242-2419. Please  refer to the document  number  on the cover  of the  issue if  available.

               Ground Water Currents  welcomes readers' comments and  contributions. Address  correspondence  to:
                     Managing  Editor,  Ground  Water  Currents  (5102W),  U.S. Environmental Protection  Agency,
                                          401  M  Street S.W., Washington,  DC 20460
 &EPA
 United States
 Environmental  Protection  Agency
 National Center for Environmental  Publications and  Information
 P.O. Box  42419
 Cincinnati. OH  45242-2419

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