NCD003446721_20040805_Celeanse Corporation - Shelby Fiber_FRBCERCLA SPD_Monitored Natural Attenuation Demonstration Project Workplan 2001 - 2004-OCR

4WDSRSEB
Mr. Steve Olp
i --~i-¾.~~:&, ·.,,,,;~v~-~---~'.1,1,,, ·o· \.· ,.~.,..-~~~~--.
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 4
ATLANTA FEDERAL CENTER
61 FORSYTH STREET .. a1i..-...,::-:-;;;"r2~~fi[l~~ ATLANTA, GEORGIA 30303-B!ll @, © ~ ti •~ @. f\1
AUG O 5 2004 ID); \\j
\~ r,.UG Y-9 2\lM
SUPERfUNO SEC1\0N
CNA Holdings, Inc., c/o Celanese
2848 Cherry Road -Suite I 00
Rock Hill, SC 29730
Subject:
Dear Mr. Olp:
EPA Comments on the document "Kubal-Furr Associates, 2004,Monitored
Natural Attenuation Demonstration Project Work Plan -Operable Unit I"
Celanese Site, Shelby, North Carolina, Civil Action No. SH-C-88-212
The purpose of this letter is to provide comments and additional guidance on the June
2004 MNA Demonstration Work Plan for the Celanese site.
In general, the work plan is adequate for an MNA investigation at this site. However, as
described in the enclosure, the monitoring network may be inadequate, particularly the number of
down graoient monitoring wells. Water level contour maps based on post-pumping conditions
should be created as soon as possible, and any needed monitoring wells should be installed. The
MNA investigation can proceed while the need for additional wells is evaluated. It is expected
that the ethylene glycol mass will move now that the pumps are off, in directions different than
observed during 15 years of pumping. A convincing network of sentinel wells should be
available along the streams or property boundary to insure that the groundwater contamination is
monitored thoroughly.
If you have any questions, please call me at 404-562-8953.
Remedial Project Manager
Superfund Remedial and Site Evaluation Branch
Enclosure
cc: David B. Mattison, NC DENR
Dave Jenkins, SRTSB
Internet Address (URL)• http:l/www.epa.gov
Recycled/Recyclable. Printed with Vegelable on Based Inks on Recycled Paper (Minimum 30% Poslconsumer)
• •
ENCLOSURE
EPA'S COMMENTS ON THE MONITORED NATURAL ATTENUATION
DEMONSTRATION PROJECT WORK PLAN
GENERAL COMMENT REGARDING THE EFFICIENCY OF THE PUMP AND
TREAT REMEDIAL MEASURE:
One of the key points made in this report appears in Section 1.3 regarding the effectiveness of the
Pump & Treat remedial measure which has been in operation at this site for years. On page 4,
the report states that " ... the Inner Tier system remains protective. but not effective as a long term
remedy." The report goes on to state that the system has maintenance problems, and that
achieving the MCLs with this system will require hundreds of years.
Two figures are presented to support the inefficiency in the system (Attachment 2). These
figures show data regarding pumping rates and volumes of water produced, not the true measure
of system efficiency which is mass of contaminant recovered. In subsequent documents, please
superimpose data showing pounds or gallons of contaminant recovered on the water production
figures to better document the performance of the pumping system.
GENERAL COMMENT REGARDING EPA POLICY APPLIED TO THIS SITE:
EPA's priil'lary concern is environmental protection, not efficiency. Pump and treat systems are
known to be capable of creating effective containment of contamination. The information
. presented in this document, particularly Figure 4 shows that containment was accomplished at
this site. Figure 4 convincingly shows that ethylene glycol was contained by the groundwater
extraction wells. The remedial measure has been a success to this time.
Any changes in the operation of this system must insure that the environment is protected.
Specifically, conditions which have been achieved by remedial activities performed to date must
not be undone. For example, the Outer Tier portion of OU! was de-listed after "Off-site
domestic well sampling reported no detectable levels of Target Compound list (TCL) organic
constituents (p. 2). Sentinel wells must be placed in a monitoring network to insure that this
progress will not be undone.
Plumes to be remediated by natural attenuation typically are stable (not expanding) or receding
under the prevailing hydraulic gradient. However, the area contaminated by ethylene glycol will
likely increase now that the pumping system is off. EPA policy typically does not condone
allowing contamination to expand into uncontaminated portions of the aquifer. At the same
time, EPA Monitored Natural Attenuation Guidelines clearly recognize that portions of certain
aquifers are already contaminated, and will be allowed to remain contaminated while natural
processes gradually remove the contamination.
2
• •
After about 15 years of pumping as part ofa remedial measure, this site is not typical. Hydraulic
gradients have been altered and a large, but unspecified mass of contaminant has been removed.
The area contaminated by ethylene glycol has been contained in a relatively small area which is
not shaped like a typical contaminant plume due to the effects of pumping.
The area of the ethylene glycol plume may expand.as it adjusts to non-pumping conditions.
Therefore, the real purpose of this step in the remediation process is to determine whether the
mass of ethylene glycol will diminish more rapidly as the surface area of the contaminant mass
increases, compared to the rate which the mass would decrease due to continued pumping.
Expanded surface area should result in an increase in biodegradation rates.
The pump and treat measure has protected the receptors identified on page 8 for the last 15 years.
The investigation must prove whether biodegradation rates can contain the plume within a
reasonable area and not degrade water resources at the receptors, specifically the streams and
private property down gradient from the site. Additional down gradient monitoring wells may
be required to obtain this proof.
GENERAL COMMENT REGARDING MONITORING WELL NETWORK AND
PROPOSED MNA MONITORING LOCATIONS:
Figure 9 shows the wells proposed for MNA parameter monitoring. The selection of these wells
is reasonable at this time. However, the contaminant distributions portrayed in the preceding
figures are the result of pumping conditions created over the last 15 years, and is not necessarily
representative of non-pumping conditions.
Also, comparison of Figure 9 with the ethylene glycol distribution on Figure 4 shows that there
are only 3 wells (W23, Q33 and 278) down gradient from the ethylene glycol mass. Only two of
these wells (W23 and Q33) are proposed for MNA monitoring. The topography of the area and
the presence of numerous ponds suggest that groundwater flow might be expected to be semi-
redial from the ridge beneath the ponds. In other words, under natural conditions, contamination
should be expected to flow toward the nearest streams (natural discharge areas) 180 degrees
around the source area, not just to the east. The existing down-gradient monitoring well network
seems inadequate.
The ethylene glycol contaminant mass shown in Figure 4 is expected to move as it adjusts to
natural hydraulic gradients. Water level contour maps, based on water levels which have
recovered to natural conditions, should be created and evaluated to determine the adequacy of the
existing monitoring well network. Installation of additional sentinel wells may be necessary.
This water level and contaminant migration evaluation must take place as soon as possible. Any
needed monitoring wells must be installed as soon as possible. This _requirement listed as the
first bullet on page 17, but the section is titled Mid-Project Data Review and Evaluation. EPA
does not agree that this task should wait until mid-project. The adequacy of the monitoring well
network must be evaluated immediately.
3
• •
COMMENT REGARDING GROUNDWATER MODELING SECTION 4.3:
The first phase of_modeling proposed in Section 4.3 (BIOSCREEN) probably is appropriate for
this site. Given that the report states that many of the well screens monitor relatively long
intervals (page 7), it is questionable whether sufficient data exists to justify application of more
advanced, 3-dimensional groundwater models. Further, EPA guidelines for MNA-require a site-
specific demonstration of MNA based on trends observed in historic data from the site. The
guidelines specifically state that models and calculations alone are not acceptable proof that
MNA will be effective at a site. This report does not propose to rely on the results of modeling
to prove that MNA is effective, but in this review of the proposed work plan, EPA stresses that
the effectiveness ofMNA will be evaluated based on site-specific observations, not predictive
groundwater modeling results. EPA recommends that modeling efforts should be kept simple for
the time being.
GENERAL COMMENT REGARDING CONTINGENCY PLANS:
A reasonable approach for this site and these conditions may be to allow plume expansion within
prescribed limits, followed by intermittent pumping when and if the contamination reaches those
limits. Two requirements, which would have be to be met prior to approval of such a plan,
would be.a demonstration that an adequate sentinel well network is present to define the post-
pumping behavior of the.plume, and a demonstration that indicator parameters are understood
sufficiently to guarantee that pumping could be resumed before contamination escaped from the
on-site natural attenuation zone. An addendum or an amendment to the work plan must be
developed""to include a contingency plan for re-starting the groundwater extraction well network
if contamination approaches any existing or new sentinel wells along the streams and property
boundary. ·
4
• •
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 4
(>'''°"'• 61 Forsyth Street, Atlanta, Georgia 30303-3104 • a • 4WD-TSS MEMORANDUM July 22, 2004 J SUBJECT: MNA Work Plan June 2004
FROM: David N. Jenkins, Environmental Scientist
Technical Services Section, Waste Management Division
CC: Jim McGuire, Chief Technical Services Section,
Waste Management Division
TO: Ken Lucas, Remedial Project Manager
Ken,
I have reviewed the revised June 2004 MNA Demonstration Work Plan for the
Celanese site in Shelby NC as you requested. My comments are summarized on this
memo. Call me 404-562-8462 if you have any questions.
The document reviewed is titled:
Kubal-Furr Associates, 2004, Monitored Natural Attenuation Demonstration Project
Work Plan -Operable Unit 1, CNA Holdings, lnc.rncona, (F.K.A. Celanese Fiber
Operations) Shelby, North Carolina, Kubal-Furr Associates, Simpsonville, SC 29680-
0247, June 2004.
GENERAL COMMENT:
In general, the work plan is adequate for an MNA investigation at this site. The list of
analyses to be performed in the field and laboratory (page 15) is reasonable. The
frequency of sampling is appropriate. However, as described below, the monitoring
network seems inadequate, particularly the number of down gradient monitoring wells.
Water level contour maps based on post-pumping conditions should be created as
soon as possible, and any needed monitoring wells should be installed. The MNA
investigation can proceed while the need for additional wells is evaluated. But as
described in other comments in this memo, the Agency expects that the ethylene glycol
mass will move now that the pumps are off, and the directions of movement may be
different than observed during 15 years of pumping. The Agency expects a that a
convincing network of sentinel wells will be available along the streams or property
boundary to insure that the groundwater contamination is monitored thoroughly during
the natural attenuation process.
GENERAL COMMENT REGARDING THE EFFICIENCY OF THE PUMP AND TREAT
REMEDIAL MEASURE:
One of the key points made in this report appears in Section 1.3 regarding the
effectiveness of the Pump & Treat remedial measure which has been in operation at
this site for years. On page 4, the report states that" ... the Inner Tier system remains
protective, but not effective as a Jong term remedy." The report goes on to state that
the system has maintenance problems, and that achieving the MCLs with this system
will require hundreds of years.
Page .1 August 2, 2004 (7:48AM) C:\TEMPIMNA wp 0406.wpd
,.
·i • •
Two figures are presented to support the inefficiency in the system (Attachment 2).
These figures show data regarding pumping rates and volumes of water produced, not
the true measure of system efficiency which is mass of contaminant recovered. Data
showing pounds or gallons of contaminant recovered should be superimposed on the
water production figures to better document the performance of the pumping system.
GENERAL COMMENT REGARDING EPA POLICY APPLIED TO THIS SITE:
The Agency's primary concern is environmental protection, not efficiency. Pump and
treat systems are known to be capable of creating effective containment of
contamination. The information presented in this document, particularly Figure 4 shows
that containment was accomplished at this site. Figure 4 convincingly shows that
ethylene glycol was contained by the groundwater extraction wells. The remedial
measure has been a success to this time.
Any changes in the operation of this system must insure that the environment is
protected. Specifically, conditions which have been achieved by remedial activities
performed to date must not be undone. For example, the Outer Tier portion of OU1
was de-listed after "Off-site domestic well sampling reported no detectable levels of
Target Compound list (TCL) organic constituents (p. 2). Sentinel wells must be placed
in a monitoring network to insure that this progress will not be undone.
Plumes to be remediated by natural attenuation typically are stable (not expanding) or
receding under the prevailing hydraulic gradient. However, the area contaminated by
ethylene glycol probably will increase now that the pumping system is off. EPA policy
typically does not condone allowing contamination to expand into uncontaminated
portions of the aquifer. At the same time, EPA Monitored Natural Attenuation
Guidelines clearly recognize that portions of certain aquifers are already contaminated,
and will be allowed to remain contaminated while natural processes gradually remove
the contamination.
After about 15 years of pumping as part of a remedial measure, this site is not typical.
Hydraulic gradients have been altered and a large, but unspecified mass of
contaminant has been removed. The area contaminated by ethylene glycol has been
contained in a relatively small area which is not shaped like a typical contaminant plume
due to the effects of pumping.
The area of the ethylene glycol plume may expand as it adjusts to non-pumping
conditions. Therefore, the real purpose of this step in the remediation process is to
determine whether the mass of ethylene glycol will diminish more rapidly as the surface
area of the contaminant mass increases, compared to the rate which the mass would
decrease due to continued pumping. Expanded surface area should result in an
increase in biodegradation rates.
The pump and treat measure has protected the receptors identified on page 8 for the
Page 2 August 2, 2004 (7:48AM) C:\TEMP\MNA wp 0406.wpd
• •
last 15 years. The investigation must prove whether biodegradation rates can contain
the plume within a reasonable area.and not degrade water resources at the receptors,
specifically the streams and private property down gradient from the site. As stated
elsewhere in this memo, additional down gradient.monitoring wells may be required to
obtain this proof.
GENERAL COMMENT REGARDING MONITORING WELL NETWORK AND
PROPOSED MNA MONITORING LOCATIONS:
Figure 9 shows the wells proposed for MNA parameter monitoring. The selection of
these wells is reasonable at this time. However, the contaminant distributions portrayed
in the preceding figures are the result of pumping conditions created over the last 15
years, and is not necessarily representative of non-pumping conditions.
Also, comparison of Figure 9 with. the ethylene glycol distribution on Figure 4 shows that
there are only 3 wells (W23, 033 and 278) down gradient from the ethylene glycol
mass. Only two of these wells (W23 and 033) are proposed for MNA monitoring. The
topography of the area and the presence of numerous ponds suggest that groundwater
flow might be expected to be semi-redial from the ridge beneath the ponds. In other
words, under natural conditions, contamination should be expected to flow toward the
nearest streams (natural discharge areas) 180 degrees around the source area, not just
to the east. The existing down-gradient monitoring well network seems inadequate.
The ethylene glycol contaminant mass shown in Figure 4 is expected to move as it
adjusts to natural hydraulic gradients. Water level contour maps, based ori water levels
which have recovered to natural conditions, should be created and evaluated to
determine the adequacy of the existing monitoring well network. Installation of
additional sentinel wells may be necessary. This water level and contaminant migration
evaluation must take place as soon as possible. Any needed monitoring wells must be
installed as soon as possible. This requirement listed as the first bullet on page 17, but
the section is titled Mid-Project Data Review and Evaluation. The Agency does not
agree that this task should wait until mid-project. The adequacy of the monitoring well
network must be evaluated immediately.
COMMENT REGARDING GROUNDWATER MODELING SECTION 4.3:
The first phase of modeling proposed in Section 4.3 (BIOSCREEN) probably is
appropriate for this site. Given that the report states that many of the well screens
monitor relatively long intervals (page 7), it is questionable whether sufficient data exists
to justify application of more advanced, 3-dimensional groundwater models. Further,
EPA guidelines for MNA require a site-specific demonstration of MNA based on trends
observed in historic data from the site. The guidelines specifically state that models
and calculations alone are not acceptable proof that MNA will be effective at a site.
This report does not propose to rely on the results of modeling to prove that MNA is
effective, but in this review of the proposed work plan, the Agency stresses that the
effectiveness of MNA will be evaluated based on site-specific observations, not
Page 3 August 2. 2004 (7:48AM) C:\TEMPIMNA wp 0406.wpd
• •
predictive groundwater modeling results. The Agency recommends that modeling
efforts should be kept simple for the time being.
GENERAL COMMENT REGARDING CONTINGENCY PLANS:
A reasonable approach for this site and these conditions may be to allow plume
expansion within prescribed limits, followed by intermittent pumping when and if the
contamination reaches those limits. Two requirements, which would have be to be met
prior to approval of such a plan, would be a demonstration that an adequate sentinel
well network is present to define the post-pumping behavior of the plume, and a
demonstration that indicator parameters are understood sufficiently to guarantee that
pumping could be resumed before contamination escaped from the on-site natural
attenuation zone. The work plan should be amended to include a contingency plan for
re-starting the groundwater extraction well network if contamination approaches any
existing or new sentinel wells along the streams and property boundary.
Page 4 August 2, 2004 (7:48AM) C:\TEMP\MNA wp 0406.wpd
•
Ms. Giezelle Bennett
Remedial Project Manager
Superfund Branch
Waste Management Division
US EPA Region IV
61 Forsyth Street, 11 th Floor
Atlanta, Georgia 30303
•
May 29, 2002
RE: Monitored Natural Attenuation Demonstration Project Work Plan
Celanese Corporation NPL Site
Shelby, Cleveland County, NC
Dear Ms. Bennett:
The Superfund Section of the North Carolina Department of Environment and Natural Resources
(NC DENR) has received and reviewed the Monitored Natural Attenuation Demonstration
Project Work Plan for the Celanese Corporation National Priorities List (NPL) Site. The
Superfund Section offers the following attached comments.
The Superfund Section of the NC DENR appreciates the opportunity to comment on this
document. If you have any questions or comments, please feel free to contact me at (919) 733-
280 I, extension 349.
Attachment
Sincerely,
David B. Mattison, CHMM
Environmental Engineer
NC Superfund Section
Ms. Giezelle Bennett
May 29, 2002
Page I
• •
MONITORED NATURAL ATTENUATION DEMONSTRATION
PROJECT WORK PLAN
CELANESE CORPORATION NPL SITE
General
I. The Monitored Natural Attenuation Demonstration Project Work Plan simply addresses
the potential for degradation of ethylene glycol at the Celanese Corporation Site (Site).
However, the monitored natural attenuation (MNA) demonstration project must
demonstrate that all contaminants in excess of remedial goals will be naturally attenuated
to the satisfaction of all applicable, relevant and appropriate requirements as specified in
the Record of Decision. Please revise this document accordingly.
Table of Contents
2. Please revise the Table of Contents indicate that the title of Table 4 is "Summary of
Minimum/Maximum Concentrations of Selected MNA Parameters."
3. Please revise the Table of Contents to indicate that the title of Table 6 is "Summary of
Annual Maximum Ethylene Glycol Concentration."
Section 1.1 Background
4. The last sentence of the first paragraph of Section 1.1 states "A site plan showing the
location of production areas, monitor wells, extraction wells, and other significant
features is shown on Figure I." Figure I simply indicates the location of the production
area and the wastewater treatment area. Please revise Figure I to include all monitoring
wells, piezometers, due diligence monitoring wells, all extraction wells, former source
area(s), surface water bodies including Buffalo Creek, and all other significant features of
the Site.
5. Section 1.1 simply identifies the families of contaminants found at the Site. Please revise
Section 1.1 to quantify and depict the type and extent, both laterally and vertically, of
contamination found at the Site. Please revise the document to include the appropriate
tables and figures to describe the historical and current concentrations of contaminants at
the Site. Additionally, please revise the document to include a figure depicting the
historical and current potentiometric surface (i.e., pre-pumping conditions (if available)
and post-pumping conditions).
Ms. Giezelle Bennett
May 29, 2002
Page2
•
Section 1.2 CERCLA Remedial Action Activities
•
6. Please clarify the meaning of the phrase "plugged back supply wells" as stated in the third
sentence of the second paragraph of Section 1.2.
Section 1.3 Monitored Natural Attenuation Demonstration Project
7. Please define the acronym "MCL" in the third sentence of Section 1.3.
8. Please delete the word "to" in the last sentence of the first paragraph of Section 1.3.
Section 2.1 Work Performed
9. The last sentence of the first paragraph indicates that the well rehabilitation program "was
expanded to include all monitor wells at the site, not just those which were part of the
MNA demonstration project." However, review of Table I and Table 2 indicates that the
piezometers, due diligence wells and Outer Tier/Inner Tier/PEW extraction wells were
not rehabilitated, including wells TI-I, TI-2, TD-3, and TD-4 which are part of the MNA
demonstration program. Please clarify this discrepancy.
I 0. The first sentence of the fourth paragraph of Section 2.1 states "All monitoring wells
were sampled using low flow purging and sampling procedures." However, review of
Table 2 the field sampling logs included as Attachment 2 indicates that the groundwater
monitoring wells were not purged a minimum of three well volumes in accordance with
Section 7 -Groundwater Sampling of the United States Environmental Protection
Agency (US EPA) Region IV Environmental Investigations Standard Operating
Procedures and Quality Assurance Manual (EISOPQAM), May 1996. Additionally, the
field sampling logs indicate that the groundwater chemistry parameters (pH, specific
conductance, temperature and turbidity) were not allowed to stabilize prior to sampling
(particularly turbidity). Please revise Section 2.1 to include the criteria used to determine
purge adequacy. Additionally, please revise this document to ensure that all future
sampling activities are conducted in accordance with the US EPA EISOPQAM.
Ms. Giezelle Bennett
May 29, 2002
Page 3
•
11. Please revise the last paragraph of Section 2.1 to discuss the potential impacts of turbidity
on the groundwater sampling and analysis performed. Results only met the performance
standard of 10 Nephelometric Turbidity Units (NTUs) once, averaged approximately 87
NTUs across all wells (those that had a well sampling log included in Attachment 2 with
the exception of extraction well IT-3), and the sample from extraction well IT-3
contained greater than 1,000 NTUs and was unable to be analyzed for sulfide and ferrous
iron concentration. Although the wells were redeveloped following surge blocking,
continued redevelopment, with pumping from the bottom of the wells to remove
accumulated silts and sediments, may be necessary to reduce extremely high turbidity
levels. Please revise this document to address actions that may be taken in order to
achieve the desired turbidity standard.
Section 2.2 Summary of the Baseline MNA Sampling Data
12. The laboratory data quality assessment included in Attachment 3 and Attachment 4
indicate that missed holding times and equipment blank contamination contributed to the
most of the data qualifiers for this sample data package. Please revise Section 2.2 to
address these issues as well as the steps to be taken to prevent future occurrences.
Section 2.3 Evidence of Natural Attenuation
13. The second paragraph of Section 2.3 references an investigation performed at the Naval
Air Warfare Center in Lakehurst, New Jersey, in which biological techniques were used
to remediate groundwater contaminated with ethylene glycol. However, the
concentrations of ethylene glycol were an order of magnitude less than those encountered
at the Site. Additionally, this paragraph indicates that the groundwater was extracted,
treated, re-injected and further treated with the addition of mineral nutrients and oxygen.
The scope of work for this project is to determine the potential of the contamination to
naturally attenuate. Please revise this section to include an explanation of the relevant
results of this investigation, including, but not limited, to the mechanism(s) for
attenuation, the conditions necessary for degradation, the byproducts of degradation, etc.
Additionally, please revise the document to include an attachment with a synopsis of the
investigation at the Naval Air Warfare Center site.
14. The first sentence of the fourth paragraph of Section 2.3 states "Ethylene glycol is readily
biodegradable under both aerobic and anaerobic conditions." Please include a reference
for this statement. Additionally, please include a synopsis of the study used to reach this
conclusion as an attachment to this document.
Ms. Giezelle Bennett
May 29, 2002
Page4
•
15. Please revise the seventh paragraph of Section 2.3 and appropriate sections of the
remainder of this document to include provisions for using an analytical technique that
can measure the full range of dissolved iron concentrations as suggested by Dr. Robert
Borden.
16. The last sentence of the tenth paragraph of Section 2.3 indicates that sulfate
concentrations decrease as ethylene glycol concentrations increase. However, the table
included in Section 2.3 does not support this hypothesis. The eighth paragraph of Section
2.3 and Dr. Robert Borden's data analysis report included as Attachment 5 indicate that
very high ethylene glycol concentrations may inhibit or slow the rate of sulfate reduction
or produce interferences in the sulfate measurement technique. Please revise Section 2.3
to eliminate these inconsistencies.
17. The last sentence of the eighth paragraph of Section 2.3 states that "Subsequent sampling
events will incorporate quality assurance checks in an attempt to resolve/quantify the
sulfate interferences." Please revise this section and appropriate sections of the remainder
of this document to specify precisely what and how the quality assurance checks are to be
performed (i.e., Dr. Borden's suggestion of spiking solutions of known sulfate
concentrations with ethylene glycol).
18. Section 2.3 does not discuss the results of dissolved oxygen (DO) analysis. Please revise
Section 2.3 to include a discussion of the DO results, causes of the irregularities,
sampling methods, equipment calibration, and methodologies to prevent future issues
with sampling equipment or the introduction of oxygen to the sample/aquifer.
19. The third sentence of the eleventh paragraph of Section 2.3 identifies the information
required to conduct any form of remediation, whether it is active or passive. Please revise
this document to identify the remedial objectives of the monitored natural attenuation
demonstration, the potential receptors, the distance (buffer zone) between the plume and
the receptors, and the ethylene glycol degradation rate. Groundwater modeling with zero
biodegradation rates should also be performed to demonstrate that sentinel wells would
detect the presence of contaminants such that remedial measures could be taken to
mitigate the spread of contamination and prevent the uptake of contaminants by the
receptors.
Section 3.2 Ground-Water Flow Rate Analysis
20. Please correct the spelling of the phrase "hydraulic characteristics" in the second sentence
of Section 3.2.
Ms. Giezelle Bennett
May 29, 2002
Page 5
• •
21. Please revise Section 3.2 to include greater detail regarding the gathering of the data
required to construct the groundwater model as well as the procedures to be used to
calibrate the model to the Site.
Section 3.4 MNA Ground-Water Monitoring Program and Data Analysis
22. Please revise the first sentence of the second paragraph of Section 3.4 to include
provisions for sulfide and carbon dioxide analyses.
Section 3.5 Transport and Attenuation Modeling
23. Please define the acronym "BTEX" in the third sentence of Section 3.5.
24. Please revise the first paragraph of Section 3.5 to detail the appropriateness of using
BIOSCREEN for evaluating the biodegradation of ethylene glycol at the Site. Please
detail how the utilization factors and/or the terminal electron acceptor (TEA) data will be
changed to account for ethylene glycol's physical and chemical characteristics as
compared to benzene/ toluene/ethyl benzene (BTEX) compounds.
25. The last sentence of the first paragraph of Section 3.5 states that "Alternative evaluation
models described below will be used as well and therefore, if it appears BIOSCREEN us
not a useful tool, it will not be carried forward any further in the analysis." Please revise
Section 3.5 to include the evaluation criteria and procedures to be used to determine if
BIOSCREEN, or any other model, is an appropriate tool for the Site. Additionally,
alternative evaluation models were inadvertently omitted from the document. Please
correct this oversight.
26. The second paragraph of Section 3.5 indicate that the software package RT3D can
simulate a multitude of scenarios including natural attenuation processes or an active
remediation for a variety of contaminants. This section further indicates that the users
can enter their own reaction kinetic expressions or choose from one of eight
preprogrammed reaction packages. Please detail the evaluation criteria and procedures to
be implemented to use this software for use at the Site.
Ms. Giezelle Bennett
May 29, 2002
Page 6
•
Section 3.6 Mid-Project Data Review and Evaluation
•
27. Section 3.6 provides a general plan for the evaluation of the monitored natural attenuation
demonstration project. However, Section 3.6 does not provide adequate detail as to how
the evaluation will be conducted. Please revise Section 3.6 to provide the criteria for
evaluating the monitoring well network, criteria for evaluating the groundwater flow
modeling, the statistical analyses to be performed for the natural attenuation data analysis,
the criteria to evaluate the natural attenuation data, the potential receptors, the human
health and ecological risk criteria, the method for calculating the degradation rates (for all
contaminants), etc. When completed, this document should provide all the necessary
information to conduct the demonstration project and evaluate its success. Please correct
these deficiencies.
Table 3 Summary of Baseline MNA Monitoring Data
28. Please revise Table 3 to include the results of turbidity analyses.
29. Please correct Table 3 to indicate that the groundwater sample collected from monitoring
well TI-I contained 1.68 milligrams per liter (mg/L) DO and 276 millivolts (mv)
reduction-oxidation (redox) potential.
30. Please correct Table 3 to indicate that the groundwater sample collected from monitoring
well V-23 contained 6,430-micromhos per centimeter (µmhos/cm) specific conductivity.
31. Please revise Table 3 to include the aerobic and anaerobic bacterial count for the two
equipment blank samples.
Table S Natural Attenuation Potential ofldentified Constituents of Concern
32. Please revise Table 5 to include a reference or references for the conclusions reached in
Table 5.
Table 6 Summary of Annual Maximum Ethylene Glycol Concentrations
33. Please define the sample location "IT Cl" in Table 6.
•
Ms. Giezelle Bennett
May 29, 2002
Page 7
Figure 6 Results of the MNA Sampling, Total Manganese
34. Please correct Figure 6 to indicate the correct isoconcentration contour line for the I 0-
mg/L label and its associated leader line.
Figure 10 Proposed MNA Monitoring Locations
35. Please revise Figure IO to indicate the location of groundwater monitoring well F-55.
Attachment 1 Letter from Jerry Kubal, Kubal-Furr & Associates to Giezelle
Bennett, EPA (July 11, 2001)
36. Please revise the cover sheet for Attachment I to state, "Letter from Jerry Kubal, Kubal-
Furr & Associates to Giezelle Bennett, EPA (July 11, 2001)."
Attachment 2 Baseline MNA Field Sampling Logs
37. The Field Sampling Logs for extraction wells lT-2, IT-4, IT-6 and IT-7 were
inadvertently omitted from Attachment 2. Please correct this oversight.
4WD SRSEB
Mr. Steve Olp
• • UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
· REGION 4
ATLANTA FEDERAL CENTER
61 FORSYTH STREET
ATLANTA, GEORGIA 30303-8960
MAY 2 0 '2004
CNA Holdings, Inc., c/o Celanese
2848 Cherry Road -Suite I 00
Rock Hill, SC 29730
Subject:
Dear Mr. Olp:
Authorization to Implement Monitored Natural Attenuation Project.
Celanese Corporation Shelby Fiber Site, Shelby, North Carolina
Consent Decree, Civil Action No_ SH-C-88-2 I 2
The purpose of this letter is to provide authorization to proceed with implementation of .
the Monitored Natural Attenuation (MNA) Demonstration Project. This work description is
contained in the "Kubal-Furr Associates, 2002, Monitored Natural Attenuation Demonstration
Project Work Plan -Operable Unit I, CNA Holdings, IncJTicona, (F.K_A. Celanese Fiber
Operations) Shelby, North Carolina, Kubal-Furr Associates, Simpsonville, SC 29680-0247, April
2002". --
This authorization is based on the Respondent's agreement to modify the work plan to
address the comments contained in this letter and discussed during our meeting of May 19, 2004.
Please revise and resubmit the work plan within 30 days of your receipt of this letter. The
revised document must include a project schedule, and schedule of deliverables. Please include
background information detailing historic contaminant levels at monitoring wells. A narative
describing contaminant distribution in the past versus the present should also be included the
document.
Enclosure
If you have any questions, please call me at 404-562-8953.
Sincerely
·✓ ;j\A/\;\,{t;\
Kenneth A Lucas
Remedial Project Manager
Superfund Remedial and Site Evaluation Branch
cc: David B. Mattison, NC DENR
Internet Address (UAL) • hnp://www.epa.gov
Recycled/Aecyclable • Printed with Vegetable Oil Based Inks on Recycled Paper {Minimum 30% Postconsumer)
• •
ENCLOSURE
EPA 'S COMMENTS ON THE MONITORED NATURAL ATTENUATION
DEMONSTRATION PROJECT WORK PLAN
GENERAL COMMENT/DIRECTION REGARDING PRESENTATION OF MNA DATA:
Comment:
Direction:
Figures 4-9 show the distribution of various contaminants in groundwater in the
OU I Inner Tier Source Area, however, these figures are less informative than
they could be. This Work Plan contains sections titled "Evidence of Natural
Attenuation", but no figures are presented for comparison of current conditions
with earlier conditions. The document contains no indication that this data
interpretation technique will be utilized. Sufficient data is available to show
conditions before and after the pump and treat operations began. Historic data is
the best evidence for natural attenuation and this must be made available for
interpretation.
New figures, similar to Figures 4-9 should be developed to show that the current
plume is smaller than the original plume.
COMMENT REGARDING THE EVIDENCE FOR MNA : .
Comment:
Direction:
The text (page 7) states that" ... ethylene glycol is readily degradable biologicallv.
few na1ural al/enuation field investigations have been conducied to address
e1hylene glycol specifzcal~v." The information from Robert C. Borden regarding
natural attenuation, presented in Attachment 5, is encouraging. In this appendix,
certain biological degradation processes are identified, and certain conditions
favorable to biological degradation are identified. The text indirectly suggests
conditions in the aquifer which may be altered to enhance contaminant
degradation. While Dr. Borden may feel that there is strong evidence of natural
attenuation processes working at this site, the presentation in Attachment 5 offers
no insight into the past or future distribution of the contaminant plume, no insight
into probable clean up times.
Because this site is going to be one of the first sites to address MNA of ethylene
glycol, there is much work to do and much documentation of the process to be
presented. EPA guidance documents for Monitored Natural Attenuation describe
the information essential for a successful evaluation of MNA. Supporting data
must be presented in future reports. Specific requirements of the EPA Guidelines
must be addressed. These must be reflected in future deliverables.
• •
RECOMMENDATIONS FOR ORGANIZATION AND PRESENTATION OF THE
EVIDENCE FOR MNA :
Comment:
Direction:·
Comment:
Continued:
Comment:
The EPA National Guidelines for Natural Attenuation require presentation of
multiple lines of evidence to support natural attenuation. Groundwater model
results generated during the forthcoming investigation need to be supported with
field data from monitoring wells which confirms that the model calculations are
correct. Rates of contaminant movement must be determined, degradation rates
calculated and clean-up times estimated.
Groundwater flow directions, vertical distribution of contamination, contaminant
trends versus time and distance from the source area, must be included in future
reports.
The following observations are from the USEP A MNA Guidelines:
I. "Understanding the contaminant flow field in the subsurface is essential for a
technically justified evaluation of an MNA remedial option; therefore, use of this
protocol is not appropriate for evaluating MNA at sites where the contaminant
flow field cannot be determined with an acceptable degree of certainty (e.g.,
complex fractured bedrock, karst aquifers)" (USEPA, 1998, p. 2).
This is a fractured rock site, and an acceptable degree of certainty is not
demonstrated in this work plan. One goal must be to try to verify than natural
attenuation is working, determine which specific processes are working in various
parts of the aquifer, how long will they continue to work and when will the site be
clean. (See excerpt from the USEPA MNA Guidelines below):
2. "Model assumptions and results should be verified by data obtained from site
characterization. If model assumptions and results are not verified by site data,
MNA is not likely to be a viable option and should not be proposed as the
remedy" (US EPA, 1998, p. 9). "The results of the modeling effort are not in
themselves sufficient proof that natural allenuation is occurring at a given site.
The results of the modeling effort are only as good as the original data input into
the model; therefore, an investment in thorough site characterization will improve
the validity of the modeling results" (USEP A, 1998, p.50).
The work plan gives no indication that an analysis of historic data available for
this site will occur. Instead, the Work Plan states (page 14) that the" ... successful
outcome of the MNA demonstration project· ... " will be judged from the first set of
samples collected following the Inner Tier shut down. Unfortunately, this method
isn't one of the lines of evidence for MNA described in the EPA guidelines. The
2
Direction:
• •
work plan does not describe how the "lines of evidence" needed to demonstrate
the bulleted items on page 14 will be accomplished. Historic. data should be
utilized to fulfill the monitoring requirements to the extent possible. Water-level
data from past and proposed sampling events should be plotted as hydrographs to
determine the seasonal stability of the water table and to determine vertical
_gradients between well pairs, whether the vertical gradients influence contaminant
migration, and whether these vertical hydraulic gradients are consistent over time.
Water level contour maps and geologic cross-sections showing monitoring well
screen intervals, depths to water and groundwater flow and _equi-potential lines
should be used to demonstrate that the wells are located to characterize the extent
of contamination, and define other conditions in the aquifer.
Water quality data should be plotted as concentration versus time. The scale of
the time axis used for water level hydrographs and water quality trend plots
should be the same to facilitate interpretation of the results. The scale of the Y
axes also should be the same from plot to plot to facilitate interpretation of the
results. Typically a logarithmic axes is used on a Y axis when data may range
over multiple orders of magnitude. The appropriate MCL (maximum contaminant
level), Target Cleanup Level or other measure of performance also can be shown
on these plots to facilitate interpreta_tion of the results.
Data collected during the investigation should be stored and reported to EPA in a
digital format, in addition to any data presented in tables and figures included in
the final report. This will facilitate the Agency's tracking and evaluation of the
MNA process.
Wells should be selected for sampling to acquire water quality samples from wells
sampled previously, so that graphs showing water quality trends over time can be
completed. Wells should be selected in the source area which will demonstrate
the decline of contaminant concentrations over time. Some wells should be
selected in the area in which previous investigations focused their efforts,
especially where contaminant concentrations were observed to have been
increasing. In addition, wells should be selected to provide water quality samples
in areas where the maps of previous investigations indicate gaps in the monitored
well network. Contaminant concentrations and concentration trends between the
source area and all natural discharge areas should be documented.
A concept model must be written which summarizes what is known about the
groundwater flow system, the extent of contamination and contaminant migration
rates. The observations, measured results and an interpretation should be included
in a description of how this site works, what is happening to groundwater
contamination and what is going to happen. This process must proceed
3
Comment:
• •
development of any groundwater flow or contaminant transport models. Methods
for determining various elements of a groundwater concept model suitable for
evaluation of MNA are described in USEP A, 1988, Wiedemeier and others, 1996,
USEP A, 1997a and 1997b. The groundwater concept model should provide the
framework for selection of depth to water measurement locations, groundwater
sampling locations and for calculations which describe contaminant migration.
The groundwater concept model should summarize in text the best available
understanding of the groundwater flow system, including but not limited to:
•
•
•
•
•
•
•
descriptions of site and area geology and hydrogeology,
descriptions of recharge areas and of natural and man-made discharge
areas
descriptions of horizontal and vertical groundwater flow directions,
descriptions of groundwater velocity and travel time to discharge areas, •
descriptions of contaminant distributions in groundwater,
descriptions of contaminant velocity and travel time to discharge areas, ·
descriptions of contaminant biodegradation rates and processes, and the
locations within the groundwater flow system where specific processes
occur.
The evaluation of natural attenuation must include (USEP A, 1998) :
I) a determination of the distribution of electron acceptors, electron do!!_ors and
metabolic by-products along the flow path,
2) a demonstration of contaminant biodegradation or reduction versus distance
along the flow path from the source, and
3) an evaluation of contaminant biodegradation or reduction versus time at
selected points along the flow path from the source.
The distribution of electron acceptors, donors and metabolic by-products (Point I)
will be a result of interpretation of data described in the Preliminary Natural
Attenuation Scoring process, which should be a one-day exercise for a site with
historic data from a good site characterization investigation. Additional lines of
evidence which support MNA will be attained by combining data from previous
investigations with the results of the proposed investigation to achieve the
evaluations described in Points 2 and 3.
COMMENT REGARDING TURBIDITY AND PURGE RA TES:
Comment: Appendix 2 shows that the turbidity in water to be sampled from many of the
wells is much higher than required by the EPA Region 4 Standard Operating
· Procedure. Appendix 2 shows that relatively low flow rates were used during
4
Direction:
• •
purging, but the data also shows that the drawdown caused during pumping was
1-10 feet in many of the wells. It is likely that lower flow rates can be
accomplished in these wells. Low flow purging should create little or no
drawdown in the well, minimizing the velocity of water entering the well,
therefore minimizing the tendency to entrain fine sediments near the well. More
importantly, data in Appendix 2 shows that typical purge times were often much
less than one hour and not all of the critical parameters stabilized during this time.
Low flow purge procedures can require many hours of purge time per well, so the
field team must be equipped to pump many wells simultaneously, then collect all
samples at the end_ofthe day. Also, the Region 4 SESD has developed a field
procedure which provides an quick distinction between settleable and colloidal
solids. Settleable solids should be eliminated. Colloidal samples should be
recognized and analyzed as is, because sorbed contamination is mobile and would
be available to a receptor from a properly constructed, well-developed water
supply well. Knowing the difference can save a money and time both during
sample collection and while making arguments to EPA. Region 4 personnel are
available to offer advice regarding the collection of low turbidity groundwater
samples. High turbidity in groundwater samples introduces and extra,
unnecessary variable in the interpretation of sample results. The collection of
turbid samples is not in the best interest of any of the parties. Arguments over
whether the results of acidified, turbid samples are real or false-positiv~r~sults are
preventable, and high quality data is needed.
The wells should be develop more thoroughly before sampling, finer well screens
and filter pack material should be installed if necessary, or the wells should be
purged more gently. In certain circumstances justification for a variance may be
made, however, without EPA's acceptance of such a justification the collection of
samples which meet the specifications of the Region 4 SOP is essential.
5
FROM:
• •
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 4
61 Forsyth Street
Atlanta, Georgia 30303-3104
May 12, 2004
4WD-OTS -DRAFT MEMORANDUM
SUBJECT: Directions to MNA Guidance Documents
David N. Jenkins, Environmental Scientist
Office of Technical Services, Waste Management Division
This memo lists selected sources of information, regulatory guidance and methodology
for Site Characterization and evaluation of Monitored Natural Attenuation. The web-site
addresses listed were accurate when this letter was created, but web-sites change and
additional search efforts may be required.
The policy Directive which clarifies EPA's policy regarding the use of monitored natural
attenuation (MNA) for the cleanup of contaminated soil and groundwater in the
Superfund, RCRA Corrective Action, and Underground Storage Tank programs.
DIRECTIVE NUMBER: 9200.4-17P Use of Monitored Natural Attenuation at
Superfund, RCRA Corrective Action, and Underground Storage Tank Sites
APPROVAL DATE: April 21, 1999
http://www.epa.gov/swerust1 /d irectiv/d9200417 .htm
The following EPA Guidelines for MNA Evaluations are available at:
http://www.epa.gov/clariton/clhtml/pubtitle.html
Wiedemeier, T.H., M.A. Swanson, D.E. Moutoux, E.K. Gordon, J.T. Wilson, B.H. Wilson,
D.H. Kampbell, P.E. Haas, R.N. Miller, J.E. Hansen, F.H. Chapelle, 1998,
TECHNICAL PROTOCOL FOR EVALUATING NATURAL ATTENUATION OF
CHLORINATED SOLVENTS IN GROUND WATER, USEPA Office of Research and
Development, Washington DC 20460, EPA/600/R-98/128, September 1998
MNA Seminar Notes (EPA/625/K-98/001)
Azadpour-Keeley, A., H.H. Russell, and G.W. Sewell, 1999, Microbial Processes Affecting
Monitored Natural Attenuation of Contaminants in the Subsurface, United States
Environmental Protection Agency, Office of Solid Waste and Emergency
Response, Office of Research and Development, EPA/540/S-99/001, September
1999.
Other published references include:
Azadpour-Keeley, A., J.W. Keeley, H.H. Russell, and G.W. Sewell, 2001, Monitored
Natural Attenuation of Contaminants in the Subsurface: Applications, Groundwater
Monitoring & Remediation, v.21, no. 3 pp. 136-143.
r •
McAllister, P.M., and C.Y. Chiang, 1994, A Practical Approach to Evaluating Natural
Attenuation of Contaminants in Groundwater, Ground Water Monitoring and
Remediation, Spring, 1994, pp. 161-173.
Byl, T.D. and S. D. Williams, Biodegradation of Chlorinated Ethanes at a Karst Site in
Middle Tennessee, USGS Water-Resources Investigations Report 99-4285.
http://water.usgs.gov/pubs/wri/wri994285/
(See Figure 1 O regarding presentation and interpretation of MNA data)
Wiedemeier, T.H., P.E. Haas, 2002, Designing Programs to Effectively Evaluate the
Performance of Natural Attenuation, Groundwater Monitoring & Remediation, Vol.22
No. 3, pp.124-135
Wiedemeier, T.H., M.A, Lucas, and P.E. Haas, 2000, Designing Monitoring Programs to
Effectively Evaluate the Performance of Natural Attenuation, Air Force Center for
Environmental Excellence (AFCEE), Technology Transfer Division, Brooks Air
Force Base, San Antonio, Texas, January 2000.
http://www.afcee.brooks.af.mil/er/ttw/natural attenuation.asp
All Monitored Natural Attenuation programs should be described, managed and optimized
using a Conceptual Site Model and a Groundwater Monitoring Plan. The following
reference includes excellent descriptions regarding the development and use of
Conceptual Site Models and Groundwater Monitoring Plans, which should be employed
at all sites with groundwater contamination. Monitored Natural Attenuation programs can
be optimized to provide cost effective data which satisfies regulatory requirements. "Five
general strategies that ensure a cost effective monitoring program include:
Reducing the number of monitoring points;
Reducing monitoring duration and/or frequency;
Simplifying analytical protocols;
Ensuring efficient field procedures; and
Streamlining data management and reporting."
U.S. Navy, 2000, Guide to Optimal Groundwater Monitoring
http://enviro.nfesc.navy.mil/erb/erb_a/support/wrk_grp/raoltm/case_studies/lnt_Final_G
uide.pdf
EPA Guidelines for Soil Screening Calculations and clean-up goal estimation are available
on the Internet at :
http://risk.lsd.ornl.gov/calc start.htm Additional information is at:
http://risk.lsd.ornl.gov/rap_hp.shtml and at
http://www.epa.goy/superfund/resources/soil/index.htm
Page 2 May 12, 2004 (2:42PM) C:\TEMPIREFS2GUIDES.wpd
•
EPA Region 4 Standard Operating Procedure:
USEPA, 1996, Region 4, Science and Ecosystem Support Division, Environmental
Investigations Standard Operating Procedures and Quality Assurance Manual, May
1996, is available at
http://www.epa.gov/region4/sesd/eisopqam/eisopqam.html
Information regarding EPA Quality Assurance Program is available at:
http://es.epa.gov/ncerqa/qa/index.html
Region 4 Quality Assurance Management Plan is available at:
http://www.epa.gov/region4/sesd/sesdpub.htm1
Information regarding EPA Digital Sample Chain of Custody Program is available at:
http:/1199.11.42. 73/ITG/forms2Iite/
Page 3 May 12, 2004 (2:42PM) C:\TEMP\REFS2GUIDES.wpd
https://cms.ncmail.net -Print View • ••
From: [e-mail]
To: Jerry Kubal <jekuba\@earthlink.net>, [e-mail], [e-mail]
Cc: [e-mail]
Subject: Celanese MNA Meeting
Date: Wed, 05 May 2004 14:35: 15 -0400
Return-Path: <[e-mail]:gov>
Original-Recipient: rfc822;[e-mail]
Received: from scc075.its.state.nc.us (207.4.22.39) by ms02.ncmail.net (6.5.029)
id 4066A8340017049A for [e-mail]; Thu, 6 May 2004 01:44:09 -0400
Received: from scc075.lts.state.nc.us (127.0.0.1) by scc075.lts.state.nc.us (6.5.029)
Id 401CD43E004154BD for [e-mail]; Thu, 6 May 2004 01:44:10 -0400
Received: from scc031.lts.state.nc.us (207.4.219.18) by scc075.its.state.nc.us (6.5.029)
id 401CD43B00405654 for [e-mail]; Thu, 6 May 2004 01:44:09 -0400
Received: from marconl.rtp.epa.gov (marconi.rtp.epa.gov [134.67.208.99])
by scc031.its.state.nc.us (8.12.10/8.12.10/DFR) with ESMTP id i465I7R6023329
for <[e-mail]>; Thu, 6 May 2004 01:44:07 -0400 (EDT)
Received: from epahubll.rtp.epa.gov (epahubll.rtp.epa.gov [134.67.213.52])
by epamail.epa.gov (PMDF V5.2-32 #42056)
with ESMTP id <[e-mail]> for [e-mail];
Thu, 6 May 2004 01 :44:06 -0400 (EDT)
Date: Wed, 05 May 2004 14:35:15 -0400
From: [e-mail]
Subject: Celanese MNA Meeting
To: Jerry Kubal <[e-mail]>, [e-mail],
[e-mail]
Cc: [e-mail]
Message-id:
<[e-mail]>
MIME-version: 1.0
X-Mailer: Lotus Notes Release 5.0.9a January 7, 2002
Content-type: text/plain; charset=US-ASCII
X-MIMETrack: Serialize by Router on EPAHUBll/USEPNUS(Release 6.0.2CF1 I lune 9,
2003) at 05/06/2004 01:44:06 AM
X-Spam-Status: Yes, hits=-98.861 requlred=S.25
X-Spam-Score: -98.861 DATE_IN_PAST_0632,NO_REAL_NAME,USER_IN_WHITELIST
X-5canned-By: MIMEDefang 2.39
Jerry, Dave and Dave:
I think that based on the discusses that we've had today we should try
to meet at the Celanese Plant on Wednesday May 19th. I'd like to
suggest that we meet early, 9 a.m. ( We can meet at the plant if Jerry
sends us directions again:)
We will likely need to do a site tour and meet from morning through
lunch. I should have EPA's comments out by tomorrow afternoon. I
expect that If we work at It, the meeting should take no longer that 3-4
hours.
I look forward to getting this done.
Kenneth A. Lucas
Remedial Project Manager
Superfund Remedial Site Evaluation Branch
U.S. Environmental Protection Agency, R4
Sam Nunn -Atlanta Federal Center
61 Forsyth Street
Atlanta, GA 30303
phone: [phone]
fax : [phone]
Page I of I
https://cms.ncmail.net/mail/MessagePrintView?sid=F2CECI 3EC90 I 099SCD45 l l 38282A... S/l 7 /2004
•. ,.
• •
These positions on the PRP's response to EPA's comments and the EPA's recent comments
on MNA work plan do not yet reflect EPA's official position. This is a starting point for
our upcoming discussions. EPA's final position on the work plan will be delivered after
our meeting during the week of May 17th.
4WDSRSEB
Mr. Steve Olp
Celanese Corporation
2300 Archdale Drive
Charlotte, North Carolina 28210
Subject: Kubal-Furr Associates, 2002, Monitored Natural Attenuation Demonstration
' Project Work Plan -Operable Unit 1, CNA Holdings, Inc.fficona, (F.K.A.
Celanese Fiber Operations) Shelby, North Carolina, Kubal-Furr Associates,
Simpsonville, SC 29680-0247, April 2002.
Dear Mr. Olp: .
Below are EPA's comments and direction for proceeding with the collection and
presentation of MNA data. The work plan as it is, presents evidence for natural attenuation,
but the evidence is in forms inconsistent with EPA guidelines. General indications that natural
attenuation will work at this site are presented, however, no information is presented regarding
contaminant trends at monitoring wells over time or contaminant distribution in the past versus
the present. The EPA MNA scoring procedure was not utilized. This procedure is meant to be a
"quick and dirty" mechanism for gauging the likelihood for a successful MNA application. This
would be an appropriated way to use the so called MNA baseline data presented in this report
GENERAL COMMENT/DIRECTION REGARDING PRESENTATION OF MNA DATA:
Comment:
Direction:
Figures 4-9 show the distribution of various contaminants in groundwater in the
OUl Inner Tier Source Area, however, these figures are less informative than
they could be. This Work Plan contains sections titled "Evidence of Natural
Attenuation", but no figures are presented for comparison of current conditions
with earlier conditions. The document contains no indication that this data
interpretation technique will be utilized. Sufficient data is available to show
conditions before and after the pump and treat operations began. Historic data is
the best evidence for natural attenuation and this must be made available for
interpretation.
New figures, similar to Figures 4-9 should be developed to show that the current
• •
plume is smaller than the original plume.
COMMENT REGARDING THE EVIDENCE FOR MNA :
Comment:
Direction:
The text (page 7) states that" ... ethylene glycol is readily degradable biologically,
few natural attenuation field investigations have been conducted to address
ethylene glycol specifically." The information from Robert C. Borden regarding
natural attenuation, presented in Attachment 5, is encouraging. In this appendix,
certain biological degradation processes are identified, and certain conditions
favorable to biological degradation are identified. The text indirectly suggests
conditions in the aquifer which may be altered to enhance contaminant
degradation. While Dr. Borden may feel that there is strong evidence of natural
attenuation processes working at this site, the presentation in Attachment 5 offers
no insight into the past or future distribution of the contaminant plume, no insight
into probable clean up times.
Because this site is going to be one of the first sites to address MNA of ethylene
glycol, there is much work to do and much documentation of the process to be
presented. EPA guidance documents for Monitored Natural Attenuation describe
the information essential for a successful evaluation of MNA. Supporting data
must be presented in future reports. Specific requirements of the EPA Guidelines
must be addressed.
RECOMMENDATIONS FOR ORGANIZATION AND PRESENTATION OF THE
EVIDENCE FOR MNA :
Comment:
Direction:
Comment:
The EPA National Guidelines for Natural Attenuation require presentation of
multiple lines of evidence to support natural attenuation. Groundwater model
results generated during the forthcoming investigation need to be supported with
field data from monitoring wells which confirms that the model calculations are
correct. Rates of contaminant movement must be determined, degradation rates
calculated and clean-up times estimated.
Groundwater flow directions, vertical distribution of contamination, contaminant
trends versus time and distance from the source area, must be included in future
reports.
The following observations are from the USEPA MNA Guidelines:
I. "Understanding the contaminant flow field in the subsurface is essential for a
technically justified evaluation of an MNA remedial option; therefore, use of this
protocol is not appropriate for evaluating MNA at sites where the contaminant
2
Continued:
Comment:
• •
flow field cannot be determined with an acceptable degree of certainty ( e.g.,
complex fractured bedrock, karst aquifers)" (USEPA, 1998, p. 2).
This is a fractured rock site, and an acceptable degree of certainty is not
demonstrated in this work plan. One goal must be to try to verify than natural
attenuation is working, determine which specific processes are working in various
parts of the aquifer, how long will they continue to work and when will the site be
clean. (See excerpt from the USEPA MNA Guidelines below):
2. "Model assumptions and results should be verified by data obtained from site
characterization. If model assumptions and results are not verified by site data,
MNA is not likely to be a viable option and should 1101 be proposed as the
remedy" (USEPA, 1998, p. 9). ''The results of the modeling effort are 1101 in
themselves sufficielll proof that natural attenuation is occurring at a given site.
The results of the modeling effort are only as good as the original data input into
the model; therefore, an investment in thorough site characterization will improve
the validity of the modeling results" (USEPA, 1998, p.50).
The work plan gives no indication that an analysis of historic data available for
this site will occur. Instead, the Work Plan states (page 14) that the" ... successful
outcome of the MNA demonstration project ... " will be judged from the first set of
samples collected following the Inner Tier shut down. Unfortunately, this method
isn't one of the lines of evidence for MNA described in the EPA guidelines. The
work plan does not describe how the "lines of evidence" needed to demonstrate
the bulleted items on page 14 will be accomplished. Historic data should be
utilized to fulfill the monitoring requirements to the extent possible. Water-level
data from past and proposed sampling events should be plotted as hydrographs to
determine the seasonal stability of the water table and to.determine vertical
gradients between well pairs, whether the vertical gradients influence contaminant
migration, and whether these vertical hydraulic gradients are consistent over time.
Water level contour maps and geologic cross-sections showing monitoring well
screen intervals, depths to water and groundwater flow and equi-potential lines
should be used to demonstrate that the wells are located to characterize the extent
of contamination, and define other conditions in the aquifer.
Water quality data should be plotted as concentration versus time. The scale of
the time axis used for water level hydrographs and water quality trend plots
should be the same to facilitate interpretation of the results. The scale of the Y
axes also should be the same from plot to plot to facilitate interpretation of the
results. Typically a logarithmic axes is used on a Y axis when data may range
over multiple orders of magnitude. The appropriate MCL (maximum contaminant
level), Target Cleanup Level or other measure of performance also can be shown
3
Direction:
• •
on these plots to facilitate interpretation of the results.
Data collected during the investigation should be stored and reported to EPA in a
digital format, in addition to any data presented in tables and figures included in
the final report. This will facilitate the Agency's tracking and evaluation of the
MNA process.
Wells should be selected for sampling to acquire water quality samples from wells
sampled previously, so that graphs showing water quality trends over time can be
completed. Wells should be selected in the source area which will demonstrate
the decline of contaminant concentrations over time. Some wells should be
selected in the area in which previous investigations focused their efforts,
especially where contaminant concentrations were observed to have been
increasing. In addition, wells should be selected to provide water quality samples
in areas where the maps of previous investigations indicate gaps in the monitored
well network. Contaminant concentrations and concentration trends between the
source area and all natural discharge areas should be documented.
A concept model must be written which summarizes what is known about the
groundwater flow system, the extent of contamination and contaminant migration
rates. The observations, measured results and an interpretation should be included
in a description of how this site works, what is happening to groundwater
contamination and what is going to happen. This process must proceed
development of any groundwater flow or contaminant transport models. Methods
for determining various elements of a groundwater concept model suitable for
evaluation of MNA are described in USEPA, 1988, Wiedemeier and others, 1996,
USEPA, 1997a and 1997b. The groundwater concept model should provide the
framework for selection of depth to water measurement locations, groundwater
sampling locations and for calculations which describe contaminant migration.
The groundwater concept model should summarize in text the best available
understanding of the groundwater flow system, including but not limited to:
•
•
•
•
•
•
•
descriptions of site and area geology and hydrogeology,
descriptions of recharge areas and of natural and man-made discharge
areas
descriptions of horizontal and vertical groundwater flow directions,
descriptions of groundwater velocity and travel time to discharge areas,
descriptions of contaminant distributions in groundwater,
descriptions of contaminant velocity and travel time to discharge areas,
descriptions of contaminant biodegradation rates and processes, and the
locations within the groundwater flow system where specific processes
occur.
The evaluation of natural attenuation must include (USEPA, 1998):
4
Comment:
• •
1) a determination of the distribution of electron acceptors, electron donors and
metabolic by-products along the flow path,
2) a demonstration of contaminant biodegradation or reduction versus distance
along the flow path from the source, and
3) an evaluation of contaminant biodegradation or reduction versus time at
selected points along the flow path from the source.
The distribution of electron acceptors, donors and metabolic by-products (Point I)
will be a result of interpretation of data described in the Preliminary Natural
Attenuation Scoring process, which should be a one-day exercise for a site with
historic data from a good site characterization investigation. Additional lines of
evidence which support MNA will be attained by combining data from previous
investigations with the results of the proposed investigation to achieve the
evaluations described in Points 2 and 3.
COMMENT REGARDING TURBIDITY AND PURGE RA TES:
Comment: Appendix 2 shows that the turbidity in water to be sampled from many of the
wells is much higher than required by the EPA Region 4 Standard Operating
Procedure. Appendix 2 shows that relatively low flow rates were used during
purging, but the data also shows that the drawdown caused during pumping was
1-10 feet in many of the wells. It is likely that lower flow rates can be
accomplished in these wells. Low flow purging should create little or no
drawdown in the well, minimizing the velocity of water entering the well,
therefore minimizing the tendency to entrain fine sediments near the well. More
importantly, data in Appendix 2 shows that typical purge times were often much
less than one hour and not all of the critical parameters stabilized during this time.
Low flow purge procedures can require many hours of purge time per well, so the
field team must be equipped to pump many wells simultaneously, then collect all
samples at the end of the day. Also, the Region 4 SESD has developed a field
procedure which provides an quick distinction between settleable and colloidal
solids. Settleable solids should be eliminated. Colloidal samples should be
recognized and analyzed as is, because sorbed contamination is mobile and would
be available to a receptor from a properly constructed, well-developed water
supply well. Knowing the difference can save a money and time both during
sample collection and while making arguments to EPA. Region 4 personnel are
available to offer advice regarding the collection of low turbidity groundwater
samples. High turbidity in groundwater samples introduces and extra,
unnecessary variable in the interpretation of sample results. The collection of
turbid samples is not in the best interest of any of the parties. Arguments over
5
Direction:
• •
whether the results of acidified, turbid samples are real or false-positive results are
preventable, and high quality data is needed.
The wells should be develop more thoroughly before sampling, finer well screens
and filter pack material should be installed if necessary, or the wells should be
purged more gently. But the collection of samples which meet the specifications
of the Region 4 SOP is essential.
If you have any questions, feel free to call me at 404-562-8953.
Sincerely
Kenneth A. Lucas
Remedial Project Manager
Superfund Remedial and Site Evaluation Branch
cc: David B. Mattison, NC DENR
6
• •
Below is the result of my review of the PRPs response to EPA's comments which were
submitted in April 2002. My position with respect to the response highlighted in bold print and
is contained in brackets [ ].
General
Comment I.The Monitored Natural Attenuation Demonstration Project Work Plan simply
addresses the potential for degradation of ethylene glycol at the Celanese Corporation Site
(Site). However, the monitored natural attenuation (MNA) demonstration project must
demonstrate that all contaminants in excess of remedial goals will be naturally attenuated
to the satisfaction of all applicable, relevant and appropriate requirements as specified in
the Record of Decision. Please revise this document accordingly.
Response I: We can indicate that all contaminants in Table 5 (Constituents of Concern) in excess
of remedial goals will be naturally attenuated to the satisfaction of all ARARs as specified in the
ROD. [ok]
Comment 2.The revised work plan addressed many of the comments provided on the
original work plan; however, several major issues need to be resolved before this workplan
can be considered ''final."
Comment 2a. Remedial action objectives, where the final receptors are, and the buffer zone
between final receptors and plume have not yet been determined.
Response 2a: The remedial action objectives are to meet the ARARs for all the COCs as
specified in the ROD and directed in comment I.
The final receptors would include off-site residents to the NE that may consume ground water
but who were not part of the voluntary watering initiative (none known at this time); children
wading in the adjacent creeks; anyone eating fish caught in the creek (unlikely); and, any
ecological receptors in the adjacent creeks.
Because of different retardation factors, degradation rates, etc., the buffer zone would depend on
the specific constituent of concern. For some constituents, the buffer zone might be several
hundred feet whereas for others, it might be several thousand. [ok]
Comment 2b. Section 3.6 provides very general description of how the MNA
Demonstration will be evaluated. It still does not provide remedial goals, benchmarks, a
decision tree, etc. These should be established now.
7
•
Response 2b: The remedial goals are the ARARs as directed in comment 1. We are willing to
work with the agencies to develop satisfactory evaluation criteria (benchmarks, decision trees,
etc.). [refer to the MNA guidelines]
Comment 2c. The concerns and the proposed actions regarding 1,4-Dioxane need to be
clearly addressed.
Response 2c: 1,4-Dioxane will be remediated to meet the ARARs, the same as any other
COC.[ok]
Table of Contents
Comment 3; Please revise the Table of Contents indicate that the title of Table 4 is
"Summary of Minimum/Maximum Concentrations of Selected MNA Parameters."
Response 3: Table title in the Contents will be revised.[ok]
Comment 4. Please revise the Table of Contents to indicate that the title of Table 6 is
"Summary of Annual Maximum Ethylene Glycol Concentration."
Response 4: Table title in the Contents will be revised.[ok]
Section 1.1 Background
Comment 5 .In the second sentence, is the word supposed to be ''faculty" or ''facility".
Response 5: It's facility.[ok]
Comment 6. The last sentence of the first paragraph of Section 1.1 states "A site plan
showing the location of production areas, monitor wells, extraction wells, and other
significant features is shown on Figure 1." Figure 1 simply indicates the location of the
production area and the wastewater treatment area. Please revise Figure 1 to include all
monitoring wells, piezometers, due diligence monitoring wells, all extraction wells, former
source area(s), surface water bodies including Buffalo Creek, and all other significant
features of the Site.
Response 6: The figure will be modified to include all requested features except for Buffalo
Creek which is too far away to be included at this scale.[ok]
Comment 7. Section 1.1 simply identifies the families of contaminants found at the Site.
Please revise Section 1.1 to quantify and depict the type and extent, both laterally and
vertically, of contamination found at the Site. Please revise the document to include the
appropriate tables and figures to describe the historical and current concentrations of
8
• •
contaminants at the Site. Additionally, please revise the document to include a figure
depicting the historical and current potentiometric conditions.
Response 7: We feel this comment is overly broad and the EPA reviewer needs to be more
specific as to the objective of the request. Not all data generated is in the database, so this would
require a report-by-report search of the historical information (pre-1989, which is about as far
back as the database goes). Regarding the tables and figures requested, there are only a few
meaningful points to plot and they are included with each semiannual report, along with a current
potentiometric surface map. Copies of tables and figures out of the most recent semiannual report
can be provided.[Alternatively, data to support this graphical presentation must be
developed during the shutdown period. Refer to MNA guidelines.}
Comment 8. Describe results of sampling conducted prior to the 1986 Remedial
Investigation. Paragraph 4 states that " ... CNA and its predecessors have been conducting
environmental investigations .. since 1981. .. " however, the document only discusses the 1986
RI.
Response 8: Responding to this comment will require a report-by-report review of all work done
prior to 1986 and we fail to see how it would add to the current understanding of conditions or
influence the scope of the work plan. This is especially true in light of the fact that significant
source-removal activities have been completed between 1990 and 1992. The current data is
significantly more reflective of current conditions.[ Refer to the MNA guidelines. Data to
support a trend vs time analysis may be developed during the shutdown period, however,
trends before and after the source removal may provide better evidence of MNA trends.]
Section 1.2 CERCLA Remedial Action Activities
Comment 9. Please clarify the meaning of the phrase "plugged back supply wells" as stated
in the third sentence of the second paragraph of Section 1.2.
Response 9: The water supply wells that the residents were using were plugged back (i.e.,
abandoned in accordance with NC regulations) as part of the voluntary initiative to provide the
residents with county water. This work was accomplished between August 1995 and April
1996.[ok]
Comment IO.Please clarify the monitoring currently taking place. It states in the first
paragraph that quarterly ground-water samples are collected from monitor wells. Isn't this
done on a semi-annual basis?
Response 10: The monitoring is done quarterly and reported semiannually. A sampling matrix
from one of the most recent semiannual reports can be provided.[ok]
9
• •
Comment 11. In paragraph two, TCE is not mentioned. It was found in one well near the
Outer Tier wells. Please include this information.
Response 11: Without knowing specifically which well the reviewer is referring to, we assume
this refers to monitor wells HH-48 and HH-77 downgradient of the facility and on the former
property of Mr. Elliott. We can indicate the Elliott wells are sampled semiannually for TCE and
that the source was never attributed to off-site migration from the plant.[ok]
Section 1.3 Monitored Natural Attenuation Demonstration Project
Comment 12. Kubal-Furr's March 8th response indicated that a draft report would not be
cited, yet the Five Year Review report prepared by Kubal-Furr and not approved by EPA
is again cited. As mentioned in the previous comments, the information can be used, but
not the report.
Response 12: We can indicate instead that Kubal-Furr performed an analysis of the OUI/OU2
remedy for Celanese and what was found. Should a reviewer of the next version of this plan ask
us to include a copy of this analysis though, what will be provided is the unapproved draft
report.[ok]
Comment 13.Please define the acronym "M CL" in the third sentence of Section 1.3.
Response 13: MCL is maximum contaminant level.[ok]
Comment 14.First paragraph, last sentence, delete the word "to" after the word "may."
Response 14: The word "to" will be deleted.[ok]
Comment IS.Text references September, 2001 as "baseline." Per our discussions, this
sampling event should not be considered "baseline" because it was conducted under
pumping conditions. The document properly notes that "baseline" conditions for MNA will
be established during the first sampling event after the pumps are shut off. Make this
section consistent with the later (and correct) sections of this document.
Response 15: In the last paragraph of Section 1.3, the term "baseline set" will be replaced by an
"initial set." The text in subsequent sections will be edited to conform with this requested
change.[ok]
Section 2,1 Work Performed
Comment 16. The last sentence of the first paragraph indicates that the well rehabilitation
program "was expanded to include all monitor wells at the site, not just those which were
part of the MNA demonstration project." However, review of Table 1 and Table 2 indicates
• •
that the piezometers, due diligence wells and Outer Tier/Inner Tier/PEW extraction wells
were not rehabilitated, including wells TI-I, TI-2, TD-3, and TD-4 which are part of the
MNA demonstration program. Please clarify this discrepancy.
Response 16: The text will be changed to indicate all monitor wells "constructed prior to due
diligence" were rehabilitated. Piezometers, PEW extraction wells and IT and OT wells should
not require an explanation, as they're not monitor wells.[ok]
Comment 17.The first sentence of the fourth paragraph of Section 2.1 states "All
monitoring wells were sampled using low flow purging and sampling procedures."
However, review of Table 2 the field sampling logs included as Attachment 2 indicates that
the groundwater monitoring wells were not purged a minimum of three well volumes in
accordance with Section 7 -Groundwater Sampling of the United States Environmental
Protection Agency (US EPA) Region IV Environmental Investigations Standard Operating
Procedures and Quality Assurance Manual (EISOPQAM), May 1996. Additionally, the
field sampling logs indicate that the groundwater chemistry parameters (pH, specific
conductance, temperature and turbidity) were not allowed to stabilize prior to sampling
(particularly turbidity). Please revise Section 2.1 to include the criteria used to determine
purge adequacy. Additionally, please revise this document to ensure that all future
sampling activities are conducted in accordance with the US EPA EISOPQAM.
Response 17: Some wells were pumped dry and could not be purged of three well volumes.
Some wells had high turbidities but indicator parameters which had stabilized. A decision was
made to sample those wells even though exceeding a criteria. The EPA SOPs will be followed in
future sampling events. Any out-of-protocol samples collected will be noted. [please see
comment letter]
Comment 18. Please revise the last paragraph of Section 2.1 to discuss the potential impacts
of turbidity on the groundwater sampling and analysis performed. Results only met the
performance standard of 10 Nephelometric Turbidity Units (NTUs) once, averaged
approximately 87 NTUs across all wells (those that had a well sampling log included in
Attachment 2 with the exception of extraction well IT-3), and the sample from extraction
well IT-3 contained greater than 1,000 NTUs and was unable to be analyzed for sulfide and
ferrous iron concentration. Although the wells were redeveloped following surge blocking,
continued redevelopment, with pumping from the bottom of the wells to remove
accumulated silts and sediments, may be necessary to reduce extremely high turbidity
levels. Please revise this document to address actions that may be taken in order to achieve
the desired turbidity standard.
Response 18: Considering the type of formation most of these wells are screened in (saprolite)
and the slot size of the well screen and size of the sand pack, some of them may never develop
out properly. Several alternatives for minimizing the turbidity can be evaluated if this continues
to be a problem. [please see comment letter]
11
• •
Section 2.2 Summary of the Baseline MNA Sampling Data
Comment 19. The laboratory data quality assessment included in Attachment 3 and
Attachment 4 indicate that missed holding times and equipment blank contamination
contributed to the most of the data qualifiers for this sample data package. Please revise
Section 2.2 to address these issues as well as the steps to be taken to prevent future
occurrences.
Response 19: We'll attempt to improve upon this item in the future, however, if the lab misses a
hold time, there's not much that can be done after the fact. Some of the analyses had 24 hour
hold times. Occasionally a hold time may get missed but the data may still be useable, at least
qualitatively. [please see comment letter]
Section 2.3 Evidence of Natural Attenuation
Comment 20.The second paragraph of Section 2.3 references an investigation performed at
the Naval Air Warfare Center in Lakehurst, New Jersey, in which biological techniques
were used to remediate groundwater contaminated with ethylene glycol. However, the
concentrations of ethylene glycol were an order of magnitude less than those encountered
at the Site. Additionally, this paragraph indicates that the groundwater was extracted,
treated, re-injected and further treated with the addition of mineral nutrients and oxygen.
The scope of work for this project is to determine the potential of the contamination to
naturally attenuate. Please revise this section to include an explanation of the relevant
results of this investigation, including, but not limited, to the mechanism(s) for attenuation,
the conditions necessary for degradation, the byproducts of degradation, etc. Additionally,
please revise the document to include an attachment with a synopsis of the investigation at
the Naval Air Warfare Center site.
Response 20: If necessary, this section can be expanded to discuss the attenuation of ethylene
glycol. The Naval Air Warfare article is only a few pages long. A complete copy will be
included. [section should explain how these results relate to expectations at the CFO site.]
Comment 21. The first sentence of the fourth paragraph of Section 2.3 states "Ethylene
glycol is readily biodegradable under both aerobic and anaerobic conditions." Please
include a reference for this statement. Additionally, please include a synopsis of the study
used to reach this conclusion as an attachment to this document.
Response 21: The "Naval Air Warfare" article cites references that note: (l) The aerobic
metabolism of ethylene glycol is relatively common, and the pathways of its metabolism are
known; and, (2) Anaerobic metabolism of ethylene glycol has been reported by Dwyer and Tiedje
(reference provided). Further, the authors go on to state: "Thus, ethylene glycol mineralization
can occur in both aerobic and anaerobic environments." As noted in response 20, a complete
copy of the Naval Air Warfare article will be attached.[See EPA position on Response 20]
13
• •
Comment 22. Please revise the seventh paragraph of Section 2.3 and appropriate sections
of the remainder of this document to include provisions for using an analytical technique
that can measure the full range of dissolved iron concentrations as suggested by Dr. Robert
Borden.
Response 22: There are no plans to substitute a method to test for the full range of ferrous iron.
The fact that it exceeds the upper range of the field test kits is in the EPA's own conclusion
indicative that iron-reducing conditions are occurring. We're proposing to substitute an alternate
indicator, manganese, for the ferrous iron. [ok]
Comment 23. Section 2.3, Page 8, Paragraph 3, Ferrous Iron Discussion: The maximum
detection limit of 10 mg/L should be sufficient to determine that iron-reducing conditions
are occurring. However, if the samples were diluted 1:1 with deionized water, the results
may provide some additional information as to the amount of iron being used as an
electron acceptor or indicate plume edges as to where the iron-reducing conditions are
greatest. If manganese is used as an alternate constituent, then dissolved manganese should
be considered.
Response 23: We can consider field dilutions for ferrous iron if the agency feels this is a critical
parameter. If manganese is used as an alternate, we can specify dissolved manganese.[let's
discuss]
Comment 24. The last sentence of the eighth paragraph of Section 2.3 states that
"Subsequent sampling events will incorporate quality assurance checks in an attempt to
resolve/quantify the sulfate interferences." Please revise this section and appropriate
sections of the remainder of this document to specify precisely what and how the quality
assurance checks are to be performed (i.e., Dr. Borden's suggestion of spiking solutions of
known sulfate concentrations with ethylene glycol).
Response 24: We will work with the laboratory to propose acceptable quality assurance checks
for sulfate interference. [ok]
Comment 25. The last sentence of the tenth paragraph of Section 2.3 indicates that sulfate
concentrations decrease as ethylene glycol concentrations increase. However, the table
included in Section 2.3 does not support this hypothesis. The eighth paragraph of Section
2.3 and Dr. Robert Borden's data analysis report included as Attachment 5 indicate that
very high ethylene glycol concentrations may inhibit or slow the rate of sulfate reduction or
produce interferences iri the sulfate measurement technique. Please revise Section 2.3 to
eliminate these inconsistencies.
Response 25: It says that the results are generally consistent with the expected findings that as
ethylene glycol increases, nitrate and sulfate will decrease while Fe+2, manganese and methane
will increase. This was not an inviolable rule, rather, it was a general consistency argument. If
14
• •
necessary, we would prefer to leave this sentence out rather than get into lengthy disagreements
and discussions over every data point that violates a general rule. [ok, however general rules
can be el_ when they are not general enough.]
Comment 26. Section 2.3 does not discuss the results of dissolved oxygen (DO) analysis.
Please revise Section 2.3 to include a discussion of the DO results, causes of the
irregularities, sampling methods, equipment calibration, and methodologies to prevent
future issues with sampling equipment or the introduction of oxygen to the sample/aquifer.
Response 26: DO was not discussed because problems with the DO meter produced data we felt
were unreliable. We can add this description to the text but don't feel a divergence into explicit
details of DO calibrations, irregularities, etc is appropriate here. It should be discussed in the data
quality assessment report in the attachments, which can then be cross referenced. [ok]
Comment 27. The third sentence of the eleventh paragraph of Section 2.3 identifies the
information required to conduct any form of remediation, whether it is active or passive.
Please revise this document to identify the remedial objectives of the monitored natural
attenuation demonstration, the potential receptors, the distance (buffer zone) between the
plume and the receptors, ·and the ethylene glycol degradation rate. Groundwater modeling
with zero biodegradation rates should also be performed to demonstrate that sentinel wells
would detect the presence of contaminants such that remedial measures could be taken to
mitigate the spread of contamination and prevent the uptake of contaminants by the
receptors.
Response 27: It's not clear that these comments refer to this paragraph. Ethylene glycol
degradation rates are something to be determined from this demonstration project. This
discussion was added at EPA's request in its first review to discuss what consideration would be
given to adding amendments to the ground water. Now that it's in here, it's being critiqued for a
different reason. We could drop the paragraph but it wouldn't be responsive to earlier EPA
comments. Also, the reference to zero biodegradation should go in the section on attenuation and
transport modeling, not here.[ok]
Comment 28. Table page 9: The text notes that as " ... ethylene glycol increases, nitrate and
sulfate will decrease, while FE2+, manganese, and methane will increase ... " The table
shown is not very consistent with this when looking at sulfate. For example, for sulfate, the
ethylene glycol concentrations are <5 for TI-1, U-38, 0-25, and W-25. However, the sulfate
concentrations widely range from <1.1 to 453 for these same concentrations. In addition, V-
23 shows an ethylene glycol concentration of 5040 and a corresponding sulfate
concentration of 41.6; IT-6 shows an ethylene glycol concentration of 5450 and a sulfate
concentration of <12. Comparing the sulfate concentrations for TI-1 (<1.1) and V-23 (41.6)
would indicate that sulfate concentrations increase with ethylene glycol. In summary, the
information in the table is inconclusive. This could also be said for the relationship between
ethylene glycol and nitrate concentrations. Nitrate is supposed to decrease with increasing
15
• •
ethylene glycol concentrations; however, 0-25 has an ethylene glycol concentration of <5
and a nitrate concentration of <0.05, while IT-6 has an ethylene glycol concentration of
5450 and a nitrate concentration of <25. Again, inconclusive.
Response 28: Admittedly, this limited data set is inconclusive with respect to nitrate and sulfate.
The weight of all evidence would indicate that natural attenuation of ethylene glycol is occurring.
This is Bob Borden's conclusion and that of every one of Celanese's consultants that have looked
at these data. We can drop this sentence from the report and replace it with language about a
preponderance of the evidence indicating degradation, if that's acceptable.[leave it in and bear
in mind that thus-far, it is EPA's position that the results are inconclusive]
Comment 29. Last paragraph page 9: Notes that certain amendments may enhance natural
attenuation, but that these should only be addressed after the " ... remedial objectives are;
where the final receptors are; what the distance is between the plume and final receptors
is; where the final receptors are; and the ethylene degradation rate." All of these criteria,
with the exception of the ethylene glycol degradation rate, should be established in this
work plan, not later in the process. This comment shows that this work plan is not yet
complete.
Response 29: We know where the final receptors are but until we know the ethylene glycol
degradation rates, we don't know if we need to amend or not to get the concentrations knocked
down more quickly. This was a generic discussion of amendment considerations, not an
indication that we don't know where the receptors are.[ok]
Section 3.0 Proposed MNA Demonstration Project Work Plan
Comment 30. In the last sentence, change the word "documenting" to "evaluating".
Response 30: The change to evaluating will be made.
Section 3.2 Ground-Water Flow Rate Analysis
Comment 31. Please correct the spelling of the phrase "hydraulic characteristics" in the
second sentence of Section 3.2.
Response 31: The typo will be corrected.[ok]
Comment 32. Please change the word "begun" to "begin" in the 5th line of the second
paragraph.
Response 32: The change to "begin" will be made.[ok]
Comment 33. Please revise Section 3.2 to include greater detail regarding the gathering of
the data required to construct the groundwater model as well as the procedures to be used
16
• •
to calibrate the model to the Site.
Response 33: The EPA needs to define "greater detail." Without some additional guidance we
are concerned that a revision will not fully meet EPA's desired criteria. [Please refer to the
MNA guidelines which are referenced in the most recent set of comments.]
Section 3.4 MNA Ground-Water Monitoring Program and Data Analysis
Comment 34. Please revise the first sentence of the second paragraph of Section 3.4 to
include provisions for sulfide and carbon dioxide analyses.
Response 34: The revision will be made.[ok]
Section 3.5 Transport and Attenuation Modeling
Comment 35. Please define the acronym "BTEX" in the third sentence of Section 3.5.
Response 35: BTEX is benzene, toluene, ethylbenzene and xylenes.[ok]
Comment 36. Please revise the first paragraph of Section 3.5 to detail the appropriateness
of using BIOSCREEN for evaluating the biodegradation of ethylene glycol at the Site.
Please detail how the utilization factors and/or the terminal electron acceptor (TEA) data
will be changed to account for ethylene glycol's physical and chemical characteristics as
compared to benzene/ toluene/ethyl benzene (BTEX) compounds.
Response 36: The paragraph indicates that we will attempt to apply BIOSCREEN by modifying
the TEAs, but, until we run it we won't know how appropriate it is. If acceptable, we can propose
how the TEAs would be changed.[ok]
Comment 37. The last sentence of the first paragraph of Section 3.5 states that "Alternative
evaluation models described below will be used as well and therefore, if it appears
BIOSCREEN is not a useful tool, it will not be carried forward any further in the
analysis." Please revise Section 3.5 to include the evaluation criteria and procedures to be
used to determine if BI OSCREEN, or any other model, is an appropriate tool for the Site.
Additionally, alternative evaluation models were inadvertently omitted from the document.
Please correct this oversight.
Response 37: The alternative evaluation model was going to be MODFLOW and RT3D. We
were in error stating "models" instead of "model".[ok]
Comment 38. The second paragraph of Section 3.5 indicates that the software package
RT3D can simulate a multitude of scenarios including natural attenuation processes or an
active remediation for a variety of contaminants. This section further indicates that the
17
•
users can enter their own reaction kinetic expressions or choose from one of eight
preprogrammed reaction packages. Please detail the evaluation criteria and procedures to
be implemented to use this software for use at the Site.
Response 38: We don't understand the request to detail the evaluation criteria and procedures to
be implemented to use this software. Can the EPA reviewer be more specific about its objectives
in this comment?[How are you going to choose from the available options?]
Section 3.5 -Transport and Attenuation Modeling
Comment 39. First paragraph -still does not demonstrate that BIOSCREEN is appropriate
for this application. In addition, the last sentence of this paragraph references
" .. Alternative evaluation methods described below .. " but no alternatives are described.
Response 39: See response to comments 36 and 37.[see response above]
Comment 40. Section 3.5, Page 13, Paragraph 1, BIOSCREEN Discussion: 2nd Sentence
would be more convincing if its use need not be limited to BTEX constituents instead of
should not be limited to BTEX constituents. 3rd Sentence needs to indicate that the TEAs
will be modified or the utilization factors changed as indicated in the BIOSCREEN User's
Manual and what those factors should be given the data available for the application in
which they want to use it. 4th Sentence needs to include information on what criteria will
be used to determine that BIOSCREEN is or is not a useful tool for this application, and
then discuss what other alternative evaluation models will be used instead or in conjunction
with if BIOSCREEN is a viable model.
Response 40: Will change the word "should" to "use" in Section 3.5, page 13, paragraph I.
The paragraph already states that the TEAs will be modified. See also response to comment 36
and 37.[ok]
Section 3.6 Mid-Project Data Review and Evaluation
Comment 41. Section 3.6 provides a general plan for the evaluation of the monitored
natural attenuation demonstration project. However, Section 3.6 does not provide adequate
detail as to how the evaluation will be conducted. Please revise Section 3.6 to provide the
criteria for evaluating the monitoring well network, criteria for evaluating the
groundwater flow modeling, the statistical analyses to be performed for the natural
attenuation data analysis, the criteria to evaluate the natural attenuation data, the potential
receptors, the human health and ecological risk criteria, break-down products, the method
for calculating the degradation rates (for all contaminants), etc. When completed, this
document should provide all the necessary information to conduct the demonstration
project and evaluate its success. Please correct these deficiencies.
18
• •
Response 41: As with comment/response 2b, we are unable to adequately respond to this
comment without first discussing with the agencies what will constitute acceptable evaluation
criteria. [refer to MNA guidelines]
Comment 42. This section does not provide specific enough remedial goals or other criteria
needed to determine the effectiveness of the monitored natural attenuation remedy, such as
definitive benchmarks, or a "decision tree" for evaluating the performance of the MNA
demonstration. It is still too vague.
Response 42: As with comment/response 2b, we are unable to adequately respond to this
comment without first discussing with the agencies what will constitute acceptable evaluation
criteria. [refer to MNA guidelines]
Section 3,7 Project Reporting and Schedule
Comment 43. A more definitive schedule is needed. How long after the sampling event will
be reports be submitted? Mid-project summary?
Response 43. We would propose reporting within 90 days of the end of the quarter being
sampled, similar to current semiannual CERCLA reporting [ok]
Table 3 Summary of Baseline MNA Monitoring Data
Comment 44. Please revise Table 3 to include the results of turbidity analyses.
Response 44: The turbidity data will be added to Table 3.[ok]
Comment 45. Please correct Table 3 to indicate that the groundwater sample collected from
monitoring well TI-1 contained 1.68 milligrams per liter (mg/L) DO and 276 millivolts (mv)
reduction-oxidation (redox) potential.
' Response 45: The table will be corrected.[ok]
Comment 46. Please correct Table 3 to indicate that the groundwater sample collected from
monitoring well V-23 contained 6,430-micromhos per centimeter (µmhos/cm) specific
conductivity.
Response 46: The table will be corrected.[ok]
Comment 47.Please revise Table 3 to include the aerobic and anaerobic bacterial count for
the two equipment blank samples.
19
•
Response 47: The table can be modified to include the requested aerobic and anaerobic bacterial
counts for the equipment blank samples [ok]
Table 5 Natural Attenuation Potential of Identified Constituents of Concern
Comment 48. Please revise Table 5 to include a reference or references for the conclusions
reached in Table 5.
Response 48: We will provide the reference or references for Table 5, the natural attenuation
potential of the COCs [ok]
Table 6 Summary of Annual Maximum Ethylene Glycol Concentrations
Comment 49. Please define the sample location "ITCI'' in Table 6.
Response 49: ITCI is the Inner Tier Combined Influent sample location.[ok]
Figure 6 Results of the MNA Sampling, Total Manganese
Comment 50. Please correct Figure 6 to indicate the correct isoconcentration contour line
for the 10-mg/L label and its associated leader line.
Response 50: Figure 6 will be corrected as requested.[ok]
Figure 10 Proposed MNA Monitoring Locations
Comment 51. Please revise Figure 10 to indicate the location of groundwater monitoring
well F-55.
Response 51: Monitor well F-55 will be added to Figure 10.[ok]
Attachment 1 • Letter from .Jerry Kubal, Kubal-Furr & Associates to Giezelle Bennett,
EPA Uuly 11, 2001}
Comment 52. Please revise the cover sheet for Attachment 1 to state, "Letter from Jerry
Kubal, Kubal-Furr & Associates to Giezelle Bennett, EPA (July 11, 2001)."
Response 52: The cover sheet can be revised as requested.[ok]
Attachment 2 -Baseline MNA Field Sampling Logs
Comment 53. The Field Sampling Logs for extraction wells IT-2, IT-4, IT-6 and IT-7 were
inadvertently omitted from Attachment 2. Please correct this oversight.
20
• •
Response 53: The field sampling logs omitted from Attachment 2, will be added to the revised
work plan.[ok]
April 19, 2002 Letter to Giezelle Bennett Re: Dioxane Sampling Results
Comment 54. This letter is inconclusive and difficult to follow. It appears to say that 1,4-
dioxane was present in groundwater, but that the highest concentration found (2.3 mg/I) is
less than the ecological toxicity screening value of 9.85 mg/I established by RUST, and less
than the RGOs of 3.58 mg/I and 2.57 mg/I for fish ingestion and child wading exposure
scenarios, respectively. Yet, the last two paragraphs of the letter discuss revisiting the 1,4-
dioxane issues. If it was previously shown that the concentrations of 1,4-dioxane are below
the established screening levels and/or RGOs, what is driving the need to re-evaluate at this
point? What specifically does CNA have in mind? Will this significantly alter and/or delay
the final development and implementation of the work plan? This needs to be clarified.
Response 54: The referenced letter was not part of the revised work plan but dioxane has been
referenced in the plan and these comments. Dioxane, as well as other COCs exceeding the
remedial goals will be remediated to meet the ARARs. Celanese has performed work to better
define the nature and extent of dioxane, but this work will not significantly alter and/or delay the
final development and implementation of the work plan [ok]
Comments from EPA's MNA expert:
Comment 55. After reading the report I have some concerns about 2 separate issues. The
first is the adequacy of this Work Plan. The second is the evaluation of the current Pump
and Treat system.
Comments on MNA Work Plan Adequacy
Overall the Work Plan is significantly deficient. The section discussing degradation of
ethylene glycol and Table 5 are helpful pieces in the Work Plan, but as a whole the Work
Plan requires considerable work. I have provided some direction below on what EPA
expects to see in the next revision. The site resides in a fractured rock hydrogeologic setting
which makes the hydrogeology of particular importance with respect to predicting the
plume attenuation and movement. Table 1 mentions "product globules" which I interpret
to be the possible presence of free product. This is an aspect of the site that may complicate
any MNA remedy for the site. The discussion of Celanese MNA in Section 2.3 is not
convincing without the data below which would present the distribution vertically and with
respect the other physical and chemical site characteristics. The plan-view approach the
PRP's are taking is insufficient and does not prepare the way for the Work Plan. An
evaluation of the monitoring system and site characterization to date is necessary to give
credibility to the conclusions drawn in Section 2. I recommend that the PRP's consultants
carefully read and implement the evaluation presented in the EPA/600/R-98/128 September
1998 Technical Protocol for Evaluating Natural Attenuation of Chlorinated Solvents in
21
• •
Ground Water. The current iteration of the Work Plan indicates this has not been done
thoroughly. The items missing from this report that are particularly important are as
follows:
1. Site hydrogeologic conceptual model
2. Site contaminant transport conceptual model
3. Cross-sections of stratigraphy, aquifers, contaminant distribution, indicator parameter
distribution, well network, top of rock, fracture system and source areas
4. Ground water potentiometric surface maps for several sampling events
5. Flownets for several sampling events
6. Basis for well placement and proposed monitoring using the above tools for
demonstration of adequacy
7. Discussion of pumping of extraction wells and supply wells on plume geochemistry and
geometry
8. Proposal to compare MNA to both an optimized pump and treat remedy and other
remedial alternatives
9. Evaluation of the adequacy of the current monitoring system to
a. Monitor plume distribution horizontally and vertically
b. Monitor plume movement horizontally and vertically
c. detect changes in environmental conditions that may reduce the efficacy of the intrinsic
degradation processes
d. Detect new releases of contaminants
10. A detailed discussion of the source material for ground water contamination and any
remaining sources and avenues for transports such as lagoons, buried utility corridors,
heterogeneous fill material, old and existing sewer lines or ditches or clay pipes, etc.
11. An evaluation of the contaminant source and changes from the time the contamination
first developed, removal or treatment actions taken at the
site and the flux of contamination out of the source over time
12. Discussion of Institutional Controls and water use changes that may occur
The above items are all important to a Work Plan because of the body of data that already
exists for the site. Building on this data set and using the data set to support the activity the
PRP's are proposing is essential. What becomes apparent in reading through the Work
Plan is that the PRP's consultants have not developed a conceptual model for the site
beyond some sampling of a few wells. The importance of the conceptual model for both
hydrogeology and contaminant transport is that each bit of concentration data, hydraulic
data, sampling field data, meteorological data, surface water stage data, and waste disposal
data is used as a line of evidence for the plume distribution and ultimately the prediction of
where and in what state the plume will end up. An expansion of Section 1.3 is necessary.
The site hydrogeologic and contaminant transport conceptual model are also important
because the reason a remedial alternative change would be implemented is because the
original site/contaminant transport conceptual has changed. A detailed discussion of this
22
•
condition is critical to the Work Plan. In Section 3.2 slug testing is proposed. It has long
been known and documented that slug tests are inadequate for determining aquifer
properties. Slug tests are used in instances where there is a lot of water to treat and no
treatment system exists, pumping of wells is not possible, or to preliminarily determine
aquifer properties; however, at Celanese pumping wells and a treatment system already
exist. I suggest that the pumping system be used to perform pumping tests to determine
aquifer properties to be used in the predictive modeling. Add water quality parameters
such as carbonate, bicarbonate, calcium, and sodium to the parameter list. There appear to
be surface water features associated with the site and no mention is made of evaluating the
impacts to these water bodies. Maps showing the horizontal and vertical distribution of all
the contaminants of concern at the site should be presented with their concentration
history. No mention is made of the transformation products for ethylene glycol or other
compounds proposed for MNA. Transformation products should be established and
included in the sampling analytical list. From the report it appears that only a subset of
wells was selected for the baseline monitoring. What are the details on how those wells
were selected and why weren't the remaining wells included? A map and construction
details on all wells should be included, along with the rational for their being omitted or
included.
Is the flow system in bedrock understood. A map and detailed discussion of this issue needs
to be included in the report since additional monitoring points, such as surface water
locations, springs and seeps may need to be added to the monitoring system. In a fractured
rock setting often the primary flow path is the rubble zone that lies at the interface to
saprolite (at this site) and bedrock.
If wells are screened above or below the primary flow zone then an inaccurate view of
attenuation processes can be developed. Attenuation may be occurring around the wells,
but not in the aquifer as a whole. Since ethylene glycol is particularly mobile, it will be
migrating swiftly is the primary flow zones are well developed. In this case degradation
reflected in the wells may not be occurring and downgradient ground water flow is
transporting undegraded ethylene glycol. The mid project review proposed in Section 3.6 is
a good concept. The monitoring well network and constituent list should be evaluated in
the Work Plan too.
Response 55. Work Plan Adequacy-What we know about the site and what is contained in the
work plan are vastly different. However, the majority of what's being asked for requires
developing an entirely new evaluation of data collected since the 1980's. It requires a critique of
the adequacy of all the work that's been done in the past including reinterpretation of" ... each bit
of concentration data, hydraulic data, sampling field data, meteorological data, surface water
stage data, and waste disposal data ... " The objective of the plan was to collect MNA data during
an evaluation period and to predict what will likely occur from this point forward, not to revisit
everything that's happened in the past. We feel that a resolution to this comment can only occur
following a site visit by the EPA reviewer and a follow-up meeting to discuss what is known
23
, .
• • •
about the site and what needs to be contained in an approvable plan.[ok]
Evaluation of Existine Remedial System
Has the remedial system evaluation been performed? If not the PRP's should be presenting
that information with a rigorous focus on the adequacy of the well network, definition of
contaminant source distribution and optimization of the pumping system. I understand a
Five Year Review was completed, but unfortunately the Five Year Review is an
administrative procedure that does not involve a detailed review of the contaminant
remedial process such as evaluation of pumping schemes, aquifer properties and the
impacts to the design. In addition to that detailed discussion and quantification of the
horizontal and vertical plume capture and development of flownets and particle tracks
should be included in the evaluation. Before the Pump and Treat System is canned this sort
of evaluation should be performed. A comparison of the an MNA remedy with an
optimized Pump and Treat is expected in the final MNA report. Two good general guides
to the evaluation is EPA/600/R-92/002 entitled General Methods for Remedial Operation
Performance Evaluation and a January 2002 document entitled Effective Management of
Operation and Maintenance for Pump and Treat Systems.
Response 55 Evaluation of Existing Remedial System-As we understand this comment, the
requested analysis can be deferred until after the MNA demonstration project is completed and a
formal request is made to modify the ROD to switch to MNA rather than pump & treat. [ok]
Conclusion
A great deal of work remains in order to produce a useful Work Plan. Demonstrating
monitored natural attenuation in a fractured rock setting where non-aqueous phase liquid
(NAPL) is present requires a particularly rigorous effort and to date not even a moderate
effort is reflected in the Work Plan. All data should be submitted electronically in a
database format so that independent data analysis can be performed by reviewers. The
submittal should include all the historic ground water hydraulic, lithologic and
contaminant concentration data. Monitoring Well, extraction well and production or
supply well construction details, surface water, soil and sediment sampling data, along with
coordinates for each point, should be included in the database.
Response 55 Conclusion-The reviewer has asked for electronic submittal of: " ... all the historic
ground water hydraulic, lithologic and contaminant concentration data. monitoring well,
extraction well and production or supply well construction details, surface water, soil and
sediment sampling data, along with coordinates for each point ... " All historical data are not
available in electronic form but the reviewer can have all that is available. [ok, the more data
the better to make the case for MNA]
24
FROM:
CC:
TO:
Ken,
• •
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 4
4WD-TSS
SUBJECT:
61 Forsyth Street
Atlanta, Georgia 30303-3104
April 23, 2004
MEMORANDUM
Review of April 2002 MNA Work Plan for the Celanese
Site Shelby NC
David N. Jenkins, Environmental Scientist
Technical Services Section, Waste Management Division
Jim McGuire, Chief Technical Services Section,
Waste Management Division
Ken Lucas, Remedial Project Manager
I have reviewed the April 2002 Work Plan for MNA at the Celanese site in Shelby NC
as you requested. My comments are summarized on this memo. Call me 404-562-
8462 if you have any questions.
The document reviewed is titled:
Kubal-Furr Associates, 2002, Monitored Natural Attenuation Demonstration Project
Work Plan -Operable Unit 1, CNA Holdings, lnc.fricona, (F.K.A. Celanese Fiber
Operations) Shelby, North Carolina, Kubal-Furr Associates, Simpsonville, SC 29680-
0247, April 2002.
GENERAL COMMENT:
This work plan is filled with encouraging thoughts, hopefully submitted with good
intentions. However, there isn't much meat in the presentation. The work plan claims
to present evidence for natural attenuation, but the evidence is in forms inconsistent
with EPA guidelines. General indications that natural attenuation will work at this site
are presented, but this isn't news. Natural attenuation works to some degree
everywhere. No information is presented regarding contaminant trends at monitoring
wells over time or contaminant distribution in the past versus the present. The EPA
MNA scoring procedure was not utilized. This procedure is meant to be a "quick and
dirty" mechanism for gauging the likelihood for a successful MNA application. It would
seem to have been an obvious way to use the so called MNA baseline data presented
in this report, but this EPA guideline procedure wasn't even mentioned.
I have included some suggestions for presentation and evaluation of MNA data in the
comments below. Please call me if you have any questions.
COMMENT REGARDING PRESENTATION OF MNA DATA:
Figures 4-9 show the distribution of various contaminants in groundwater in the OU1
Inner Tier Source Area. As a first time reviewer of documents for this site, these figures
Page 1 May 5, 2004 (11 :50AM) C:\TEMPIMNA Work Plan Comments.wpd
• 0
probably are less informative than they could be. This Work Plan contains sections
titled "Evidence of Natural Attenuation", but no figures are presented to for comparison
of current conditions with earlier conditions. This is one of the most basic lines of
evidence for a justification of natural attenuation, but the document contains no
indication that this data interpretation technique will be utilized.
Presumably, figures similar to Figures 4-9 are available for some contaminants from the
mid-1980s, and presumably a comparison of these figures would show the current
plume is smaller than the original plume. Hopefully, sufficient data is available to show
conditions before and after the pump and treat operations began. Unfortunately, no
historic data is presented in these figures, so some of the best evidence for natural
attenuation is not available for interpretation. Given that two decades of environmental
monitoring data area available, the failure to present or promise to present what should
be a favorable picture of the site, using techniques typically used in MNA
demonstrations, is puzzling.
COMMENT REGARDING THE EVIDENCE FOR MNA :
The text (page 7) states that" ... ethylene glycol is readily degradable biologically, few
natural attenuation field investigations have been conducted to address ethylene glycol
specifically. The information from Robert C. Borden regarding natural attenuation,
presented in Attachment 5, is encouraging. In this appendix, certain biological
degradation processes are identified, and certain conditions favorable to biological
degradation are identified. The text indirectly suggests conditions in the aquifer which
may be altered to enhance contaminant degradation. While Dr. Borden may feel that
there is strong evidence of natural attenuation processes working at this site, the
presentation in Attachment 5 offers no insight into the past or future distribution of the
contaminant plume, no insight into probable clean up times.
If this site is going to be one of the first sites to address MNA of ethylene glycol, there is
much work to do and much documentation of the process to be presented. EPA
guidance documents for Monitored Natural Attenuation describe the information
essential for a successful evaluation of MNA. This data may be available in previous
reports for this site, but the supporting data is not presented in this work plan and there
is no indication that it will be presented. Natural attenuation probably is working at this
site. It appears to work everywhere to some degree. While it may be the intention to
present the appropriate data to document the process in future reports, this document
does not indicate that this will occur. Specific requirements of the EPA Guidelines are
not addressed, and there are no specific indications that they will be addressed.
RECOMMENDATIONS FOR ORGANIZATION AND PRESENTATION OF THE
EVIDENCE FOR MNA :
The EPA National Guidelines for Natural Attenuation require presentation of multiple
lines of evidence to support natural attenuation. Groundwater model results generated
during the proposed investigation need to be supported with field data from monitoring
Page 2 May 5, 2004 (11 :S0AM) C:\TEMPIMNA Work Plan Comments.wpd
• •
wells which confirms that the model calculations are correct. Rates of contaminant
movement must be determined, degradation rates calculated and clean-up times
estimated. Therefore, if MNA is to be utilized at this site in any form, issues regarding
the concept model and groundwater flow system must be resolved to the Agency's
satisfaction. This work plan does not show groundwater flow directions, vertical
distribution of contamination, contaminant trends versus time and distance from the
source area, and the work plan gives no indication that presentation of this information
will be included in future reports.
The following observations are from the USEPA MNA Guidelines:
1. "Understanding the contaminant flow field in the subswface is essential for a
technically justified evaluation of an MNA remedial option; therefore, use of this
protocol is not appropriate for evaluating MNA at sites where the contaminant flow field
cannot be detennined with an acceptable degree of certainty ( e.g., complex fractured
bedrock, karst aquifers)" (USEPA, 1998, p. 2).
This is a fractured rock site, and an acceptable degree of certainty is not demonstrated
in this work plan.
One goal must be to try to verify than natural attenuation is working, determine which
specific processes are working in various parts of the aquifer, how long will they
continue to work and when will the site be clean.
2. "Model assumptions and results should be verified by data obtained from site
characterization. If model assumptions and results are not verified by site data, MNA is
not likely to be a viable option and should not be proposed as the remedy "(US EPA,
1998, p. 9). 'The results of the modeling effort are not in themselves sufficient proof
that natural attenuation is occurring at a given site. The results of the modeling effort are
only as good as the original data input into the model; therefore, an investment in
thorough site characterization will improve the validity of the modeling results"
(USEPA, 1998, p.50).
The work plan gives no indication that an analysis of historic data available for this site
will occur. Instead, the Work Plan states (page 14) that the" ... successful outcome of
the MNA demonstration project ... " will be judged from the first set of samples collected
following the Inner Tier shut down. Unfortunately, this method isn't one of the lines of
evidence for MNA described in the EPA guidelines. The work plan does not describe
how the "lines of evidence" needed to demonstrate the bulleted items on page 14 will
be accomplished.
Historic data should be utilized to fulfill the monitoring requirements to the extent
possible.
Water-level data from past and proposed sampling events should be plotted as
hydrographs to determine the seasonal stability of the water table and to
Page 3 May 5, 2004 (11 :S0AM) C:\TEMPIMNA Work Plan Comments.wpd
• •
determine vertical gradients between well pairs, whether the vertical gradients
influence contaminant migration, and whether these vertical hydraulic gradients
are consistent over time.
Water level contour maps and geologic cross-sections showing monitoring well
screen intervals, depths to water and groundwater flow and equi-potential lines
should be used to demonstrate that the wells are located to characterize the
extent of contamination, and define other conditions in the aquifer.
Water quality data should be plotted as concentration versus time. The scale of
the time axis used for water level hydrographs and water quality trend plots
should be the same to facilitate interpretation of the results.
Data collected during the investigation should be stored and reported to EPA in a
digital format, in addition to any data presented in tables and figures included in
the final report. This will facilitate the Agency's tracking and evaluation of the
MNA process.
Wells should be selected for sampling to acquire water quality samples from wells
sampled previously, so that graphs showing water quality trends over time can be
completed. Wells should be selected in the source area which will demonstrate the
decline of contaminant concentrations over time. Some wells should be selected in the
area in which previous investigations focused their efforts, especially where
contaminant concentrations were observed to have been increasing. In addition, wells
should be selected to provide water quality samples in areas where the maps of
previous investigations indicate gaps in the monitored well network. Contaminant
concentrations and concentration trends between the source area and all natural
discharge areas should be documented.
A concept model should be written which summarizes what is known about the
groundwater flow system, the extent of contamination and contaminant migration rates.
The observations, measured results and an interpretation should be included in a
description of how this site works, what is happening to groundwater contamination and
what is going to happen. Clearly this process should proceed development of any
groundwater flow or contaminant transport models. Methods for determining various
elements of a groundwater concept model suitable for evaluation of MNA are described
in USEPA, 1988, Wiedemeier and others, 1996, USEPA, 1997a and 1997b. The
groundwater concept model should provide the framework for selection of depth to
water measurement locations, groundwater sampling locations and for calculations
which describe contaminant migration. The groundwater concept model should
summarize in text the best available understanding of the groundwater flow system,
including but not limited to:
descriptions of site and area geology and hydrogeology,
descriptions of recharge areas and of natural and man-made discharge areas,
Page 4 May 5, 2004 (11 :50AM) C:ITEMP\MNA Work Plan Comments.wpd
• •
descriptions of horizontal and vertical groundwater flow directions,
descriptions of groundwater velocity and travel time to discharge areas,
descriptions of contaminant distributions in groundwater,
descriptions of contaminant velocity and travel time to discharge areas,
descriptions of contaminant biodegradation rates and processes, and the
locations within the groundwater flow system where specific processes
occur.
An evaluation of natural attenuation should include (USEPA, 1998) :
1) a determination of the distribution of electron acceptors, electron donors and
metabolic by-products along the flow path,
2) a demonstration of contaminant biodegradation or reduction versus distance
along the flow path from the source, and
3) an evaluation of contaminant biodegradation or reduction versus time at
selected points along the flow path from the source.
The distribution of electron acceptors, donors and metabolic by-products (Point 1) will
be a result of interpretation of data described in the Preliminary Natural Attenuation
Scoring process, which should be a one-day exercise for a site with historic data from a
good site characterization investigation. Additional lines of evidence which support
MNA will be attained by combining data from previous investigations with the results of
the proposed investigation to achieve the evaluations described in Points 2 and 3.
COMMENT REGARDING TURBIDITY AND PURGE RATES:
Appendix 2 shows that the turbidity in water to be sampled from many of the wells is
much higher than required by the EPA Region 4 Standard Operating Procedure.
Appendix 2 shows that relatively low flow rates were used during purging, but the data
also shows that the drawdown caused during pumping was 1-10 feet in many of the
wells. It is likely that lower flow rates can be accomplished in these wells. Low flow
purging should create little or no drawdown in the well, minimizing the velocity of water
entering the well, therefore minimizing the tendency to entrain fine sediments near the
well. More importantly, data in Appendix 2 shows that typical purge times were often
much less than one hour and not all of the critical parameters stabilized during this
time.
Low flow purge procedures can require many hours of purge time per well, so the field
team must be equipped to pump many wells simultaneously, then collect all samples at
the end of the day. Also, the Region 4 SESD has developed a field procedure which
provides an quick distinction between settleable and colloidal solids. Settleable solids
should be eliminated. Colloidal samples should be recognized and analyzed as is,
because sorbed contamination is mobile and would be available to a receptor from a
properly constructed, well-developed water supply well. Knowing the difference can
save a money and time both during sample collection and while arguing with the
Agency. Region 4 personnel are available to offer advice regarding the collection of low
turbidity groundwater samples.
Page 5 May 5, 2004 (11 :50AM) C:\TEMP\MNA Work Plan Comments.wpd
• •
High turbidity in groundwater samples introduces and extra, unnecessary variable in the
interpretation of sample results. The collection of turbid samples is not in the best
interest of any of the parties. The Agency has no desire to spend hours of time over
the next few years arguing whether the results of acidified, turbid samples are real or
false-positive results. This is preventable, and high quality data is needed. The wells
should be develop more thoroughly before sampling, finer well screens and filter pack
material should be installed if necessary, or the wells should be purged more gently.
But the collection of samples which meet the specifications of the Region 4 SOP is
essential.
Page 6 May 5, 2004 (11 :50AM) C:ITEMPIMNA Work Plan Comments.wpd
• •
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
4WD-NSMB
Mr. Steve Olp
Sr. Remediation Manager
Celanese Americas Corp.
2300 Archdale Dr.
P.O. Box 32414
Charlotte, NC 28232
SUBJ: Celanese NPL Site
Shelby, NC
Dear Mr. Olp:
REGION 4
61 Forsyth Street, S.W.
Atlanta, Georgia 30303-3104
July 2, 2002
In response to your June 25, 2002 letter, both EPA and NC DENR would like to
reiterate our commitment in the August 29, 2001 Five-Year Review to "grant the PRP's
request to determine if monitored natural attenuation (MNA) would be effective at the
Site and turn-off the groundwater pump-and-treat system for a period of twenty-four
(24) months to allow the aquifer to recover and to investigate other potential remedies."
In an effort to jump start the determination, the Agencies offered, in a recent conference
call with Kubal and Furr, to allow Celanese to go ahead and turn the pumps off. The
24-month period would begin upon approval of the work plan. This offer was declined.
In your letter, you state that the site has undergone 10 years of on-going pump
and treat, yet when the Agencies requested a summary of the data, we were told it was
not readily available; it was in a warehouse. The question is, why would your company
spend money on analysis and not keep a summary table of the data collected to date?
I have enclosed a quarterly report from another NPL site that shows a clear example of
how to keep up with data collected. Of particular note are the hydrographs, time-
concentration plots and time-concentration tables.
One of the common misconceptions about MNA is that it is a "do-nothing"
remedy. This is far from factual. MNA may be "harder'' to implement than a general
pump-and-treat remedy.
• •
The Agencies would like to meet with your company as soon as possible to
discuss the MNA. However, without a response to the comments, or at least an attempt
to collect the information requested in the comments, the meeting may not be as fruitful
as all parties are expecting.
I have attempted to call you to discuss this matter, but have been unable to
reach you. Please give me a call at 404-562-8824 so that we may come to a
satisfactory resolution to the groundwater remedy at this Site.
Sincere! ,
CV,!o/~
ezelle S. Bennett
Remedial Project Manager
cc: David Mattison, NC DENR
John Blanchard, B&V
Jerry E. Kubal, Kubal & Furr
' .rJ;n-1,~01 02:26pm Frcm-Narth S1Jparfund •
CERTIFIED MAIL -R.R.R
.lune 25, 2002
Ms. Giezelle S. Bennett
U.S. EPA, Region IV
61 Forsyth Street
Atlanta, GA 30303
[phone] P 001/001 F-556 • f) Celanese
-·------·-
OF"TIONAL FORM 8!l (°l-B0J
FAX TRANSMITTAL ;olpagos• a....
GENERA[. SERVICES AD.Y.ifJISTAA'rlOfJ
Re: Ticona/Shelby-MNA \Vork Plan Comments-June 5, 2002
Dear Ms. Bcnnen:
We have received and reviewed your comments on our most recent !'vlNA
demonstration project work plan submittal for the Ticona-Shelby, NC facility. As you discussed with Jerry Kubal on June 10, 2ff02, considering the extensive nature of this round of EPA and NCDENR com.'11ents, we have requested a meeting with the various agency reviewers to discuss the plan, and 10 realistically evaluate whether or not we cari develop an approvable document before preparing any further revisions to this plan.
1n early meetings, discussions and correspondence during development of the '80rk plan. we fell the agencies were in support of our efforts t0 evaluate alternatives to the currcm pump and treat system. At th.is point, we have submined two work plans and have received three sets of agency comments. Unfortunately, the 20-year his10ry of investigations conducted at the site and the more than l 0 years of on-going pump and treat do not appear tO factor into the agencies' comments. Rather than converging on an approvabk document, the most recent comments would indicate that the agencies prefer the existing pump and treat remedy over an evaluation of the efficacy of i'vlNA as a treatmem alternative.
02:28pm From-North Suparfund
G. Bennett
J,me 25, 2002
p 2
• [phone] T-689 P 002/002 F-556 •
Our understanding is that the earliest the requested meeting can occur is sometime in early August. We propose to defer any written reply to your specific comments until after
our meeting and will not be submitting any additional infom1ation in response to the June 28 th deadline mentioned in your June 5"' cover letter. Please ca!! me if you'd like to
discuss this before our meeting. I can be reilched at 704-554-3892
:?:~ Steve Olp
Sr. Remediation Manager
cc: J. Kubal -Ku ball & Furr
['. Carter -Ticona
M. Schroeder -Ticona
• • UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 4
ATLANTA FEDERAL CENTER
61 FORSYTH STREET
ATLANTA, GEORGIA 30303-8960 -----r:--: --\/ I ~J· ;., ( ', 1, \'' ',,r ,,
4WD-NSMB
Mr. Steve Olp
Sr. Remediation Manager
Celanese Americas Corp.
2300 Archdale Dr.
P.O. Box32414
Charlotte, NC 28232
SUBJ: Celanese NPL Site
Shelby, NC
Dear Mr. Olp:
June 5, 2002 \·' \ JUN -6 'j I
\ '
i ., .
\ : ' . " •~, I '
L--
The Environmental Protection Agency has reviewed the April 29, 2002
Monitored Natural Attenuation Demonstration Project Work Plan. Please submit a
response to these comments to the Agency no later than June 28, 2002.
If you have any questions, please give me a call at 404-562-8824.
0l~~
cc: David Mattison, NC DENR
John Blanchard, B&V
Remedial Project Manager
Jerry E. Kubal, Kubal & Furr
Internet Address (URL) • http://www.epa.gov
Recycled/Recyclable. Prinled with Vegetable on Based Inks on Recycled Paper (Minimum 30% Postconsumer)
2002
I . -
~ I ' ,11\
~
I ••• -:...--__ J
• • MONITORED NATURAL ATTENUATION DEMONSTRATION
PROJECT WORK PLAN APRIL 2002
CELANESE CORPORATION NPL SITE
General
1. The Monitored Natural Attenuation Demonstration Project Work Plan simply
addresses the potential for degradation of ethylene glycol at the Celanese
Corporation Site (Site). However, the monitored natural attenuation (MNA)
demonstration project must demonstrate that ill! contaminants in excess of
remedial goals will be naturally attenuated to the satisfaction of all applicable,
relevant and appropriate requirements as specified in the Record of Decision.
Please revise this document accordingly.
· 2. The revised work plan addressed many of the comments provided on the original
work plan; however, several major issues need to be resolved before this .
workplan can be considered "final."
a. Remedial action objectives, where the final receptors are, and the buffer
zone between final receptors and plume have not yet been determined ..
b. Section 3.6 provides very general description of how the MNA
Demonstration will be evaluated. It still does not provide remedial goals,
benchmarks, a decision tree, etc. These should be established now.
c. The concerns and the proposed actions regarding 1,4-Dioxane need to be
clearly addressed.
Table of Contents
3. Please revise the Table of Contents indicate that the title of Table 4 is "Summary of
_Minimum/Maximum Concentrations of Selected MNA Parameters."
4. Please revise the Table of Contents to indicate that the title of Table 6 is "Summary of
Annual Maximum Ethylene Glycol Concentration."
Section 1.1 Background
5. In the second sentence, is the word supposed to be "faculty" or "facility".
6. The last sentence of the first paragraph of Section 1.1 states "A site plan showing the
location of production areas, monitor wells, extraction wells, and other significant
features is shown on Figure 1." Figure 1 simply indicates the location of the
production area and the wastewater treatment area. Please revise Figure 1 to include
all monitoring wells, piezometers, due diligence monitoring wells, all extraction wells,
former source area(s), surface water bodies including Buffalo Creek, and all other
significant features of the Site.
7. Section 1.1 simply identifies the families of contaminants found at the Site. Please
revise Section 1.1 to quantify and depict the type and extent, both laterally and
- 1 -
•
vertically, of contamination found at the Site. Please revise the document to include
the appropriate tables and figures to describe the historical and current concentrations
of contaminants at the Site. Additionally, please revise the document to include a
figure depicting the historical and current potentiometric surface (i.e., pre-pumping
conditions (if available) and post-pumping conditions).
8. Describe results of sampling conducted prior to the 1986 Remedial Investigation.
Paragraph 4 states that " .. CNA and its predecessors have ben conducting
environmental investigations .. since 1981 .. " however, the document only discusses
the 1986 RI.
Section 1.2 CERCLA Remedial Action Activities
9. Please clarify the meaning. of the phrase "plugged back supply wells" as stated in the
third sentence of the second paragraph of Section 1.2.
10. Please clarify the monitoring currently taking place. It states in the first paragraph that
quarterly ground-water samples are collected from monitor wells. Isn't this done on a
semi-annual basis?
11. In paragraph two, TCE is not mentioned. It was found in one well near the Outer Tier
wells. Please include this information.
Section 1.3 Monitored Natural Attenuation Demonstration Project
12. Kubal-Furr;s March 8th response indicated that a draft report would not be cited, yet
the Five Year Review report prepared by Kubal-Furr and not approved by EPA is
again cited. As mentioned in the previous comments, the information can be used,
but not the report.
13. Please define the acronym "MCL" in the third sentence of Section 1.3.
14. First paragraph, last sentence, delete the word "to" after the word "may."
15. Text references September, 2001 as "baseline." Per our discussions, this sampling
event should not be considered "baseline" because it was conducted under pumping
conditions. The document properly notes that "baseline" conditions for MNA will be
established during the first sampling event after the pumps are shut off. Make this
section consistent with the later (and correct) sections of this document.
Section 2.1 Work Performed
16. The last sentence of the first paragraph indicates that the well rehabilitaiion program
"was expanded to include all monitor wells at the site, not just those which were part of
the MNA demonstration project." However, review of Table 1 and Table 2 indicates
that the piezometers, due diligence wells and Outer Tier/Inner Tier/PEW ex1raction
wells were not rehabilitated, including wells Tl-1, Tl-2, TD-3, and TD-4 which are part
of the MNA demonstration program. Please clarify this discrepancy.
- 2 -
• • 17. The first sentence of the fourth paragraph of Section 2.1 states "All monitoring wells
were sampled using low flow purging and sampling procedures." However; review of
Table 2 the field sampling logs included as Attachment 2 indicates that the
groundwater monitoring wells were not purged a minimum of three well volumes in
accordance with Section 7 -Groundwater Sampling of the United States
Environmental Protection Agency (US EPA) Region IV Environmental Investigations.
Standard Operating Procedures and Quality Assurance Manual (EISOPQAM), May
1996. Additionally, the field sampling logs indicate that the groundwater chemistry
parameters (pH, specific conductance, temperature and turbidity) were not allowed to
stabilize prior to sampling (particularly turbidity). Please revise Section 2.1 to include
the criteria used to determine purge adequacy. Additionally, please revise this
document to ensure that all future sampling activities are conducted in accordance
with the US EPA EISOPOAM.
18. Please revise the last par.f!graph of Section 2.1 to discuss the potential impacts of
turbidity on the groundwater sampling-and analysis performed. Results only met the
performance standard of 10 Nephelometric Turbidity Units (NTUs) once, averaged
approximately 87 NTUs across all wells (those that had a well sampling log included in
Attachment 2 with the exception of extraction well lT-3), and the sample from
extraction well lT-3 contained greater than 1,000 NTUs and was unable to be
analyzed for sulfide and ferrous iron concentration. Although the wells were
redeveloped following surge blocking, continued redevelopment, with pumping from
the bottom of the wells to remove accumulated silts and sediments, may be necessary
to reduce extremely high turbidity levels. Please revise this document to address
actions that may be taken in order to achieve the desired turbidity standard.
Section 2.2 Summary of the Baseline MNA Sampling Data
19. The laboratory data quality assessment included in Attachment 3 and Attachment 4
indicate that missed holding times and equipment blank contamination contributed to
the most of the data qualifiers for this sample data package. Please revise Section
2.2 to address these issues as wel! as the steps to be taken to prevent future
occurrences.
Section 2.3 Evidence of Natural Attenuation
· 20. The second paragraph of Section 2.3 references an investigation performed at the
Naval Air Warfare Center in Lakehurst, New Jersey, in which biological techniques
were used to remediate groundwater contaminated with ethylene glycol. However, the
concentrations of ethylene glycol were an order of magnitude less than those
encountered at the Site. Additionally, this paragraph indicates that the groundwater
was extracted, treated, re-injected and further treated with the addition of mineral
nutrients and oxygen. The scope of work for this project is to determine the potential
of the contamination to naturally attenuate. Please revise this section to include an
explanation of the relevant results of this investigation, including, but not limited, to the
mechanism(s) for attenuation, the conditions necessary for degradation, the
byproducts of degradation, etc. Additionally, please revise the document to include an
attachment with a synopsis of the investigation at the Naval Air Warfare Center site.
- 3 -
• • 21. The first sentence of the fourth paragraph of Section 2.3 states "Ethylene glycol is
readily biodegradable under both aerobic and anaerobic conditions." Please include a
reference for this statement. Additionally, please include a synopsis of the study used
to reach this conclusion as an attachment to this document.
22. Please revise the seventh paragraph of Section 2.3 and appropriate sections of the
remainder of this document to include provisions for using an analytical technique that
can measure the full range of dissolved iron concentrations as suggested by Dr.
Robert Borden.
23. Section 2.3, Page 8, Paragraph 3, Ferrous Iron Discussion: The maximum detection
limit of 10 mg/L should be sufficient to determine that iron-reducing conditions are
occurring. However, if the samples were diluted 1 :1 with deionized water, the results
may provide some additional information as to the amount of iron being used as an
electron acceptor or indicate plume edges as to where the iron-reducing conditions
-are greatest. If manganese is used as an alternate constituent, then dissolved
manganese-should be considered.
24. The last sentence of the eighth paragraph of Section 2.3 states that "Subsequent
sampling events will incorporate quality assurance checks in an attempt to
resolve/quantify the sulfate interferences." Please revise this section and appropriate
sections of the remainder of this document to specify precisely what and how the
quality assurance checks are to be performed (i.e., Dr. Borden's suggestion of spiking
solutions of known sulfate concentrations with ethylene glycol).
25. The last sentence of the tenth paragraph of Section 2.3 indicates. that sulfate
concentrations decrease as ethylene glycol concentrations increase. However, the
table included in Section 2.3 does not support this hypothesis. The eighth paragraph
of Section 2.3 and Dr. Robert Borden's data analysis report included as Attachment 5
indicate that very high ethylene glycol concentrations may inhibit or slow the rate of
sulfate reduction or produce interferences in the sulfate measurement technique.
Please revise Section 2.3 to eliminate these inconsistencies.
26. Section 2.3 does not discuss the results of dissolved oxygen (DO) analysis. Please
revise Section 2.3 to include a discussion of the DO results, causes of the
irregularities, sampling methods, equipment calibration, and methodologies to prevent
future issues with sampling equipment or the introduction of oxygen to the
sample/aquifer.
27. The third sentence of the eleventh paragraph of Section 2.3 identifies the information
required to conduct any form of remediation, whether it is active or passive. Please
revise this document to identify the remedial objectives of the monitored natural
attenuation demonstration, the potential receptors, the distance (buffer zone) between
the plume and the receptors, and the ethylene glycol degradation rate. Groundwater
modeling with zero biodegradation rates should also be performed to demonstrate that
sentinel wells would detect the presence of contaminants such that remedial
measures could be taken to mitigate the spread of contamination and prevent the
uptake of contaminants by the receptors.
- 4 -
• • 28. Table page 9: The text notes that as " ... ethylene glycol increases, nitrate and sulfate
will decrease, while FE2+, manganese, and methane will increase ... " The table
shown is not very consistent with this when looking at sulfate. For example, for
sulfate, the ethylene glycol concentrations are <5 for Tl-1, U-38, 0-25, and W-25.
However, the sulfate concentrations widely range from <1.1 to 453 for these same
concentrations. In addition, V-23 shows an ethylene glycol concentration of 5040 and
a corresponding sulfate concentration of 41.6; IT-6 shows an ethylene glycol
concentration of 5450 and a sulfate concentration of <12. Comparing the sulfate
concentrations for Tl-1 (<1.1) and V-23 (41.6) would indicate that sulfate
concentrations increase with ethylene glycol. In summary, the information in the table
is inconclusive. This could also be said for the relationship between ethylene glycol
and nitrate concentrations. Nitrate is supposed to decrease with increasing ethylene
glycol concentrations; however, 0-25 has an ethylene glycol concentration of <5 and a
nitrate concentration of <0.05, while IT-6 has an ethylene glycol concentration of 5450
and a nitrate concentration of <25. Ags!in, inconclusive.
29. Last paragraph page 9: Notes that certain amendments may enhance natural
attenuation, but that these should only be addressed after the " .. remedial objectives
are; where the final receptors are; what the distance is between the plume and final
receptors is; where the final receptors are; and the ethylene degradation rate." All of
these criteria, with the exception of the ethylene glycol degradation rate, should be ·
established in this work plan, not later in the process. This comment shows that this
work plan is not yet complete.
Section 3.0 Proposed MNA Demonstration Project Work Plan
30. In the last sentence, change the word "documenting" to "evaluating".
Section 3.2 Ground-Water Flow Rate Analysis
31. Please correct the spelling of the phrase "hydraulic characteristics" in the second
sentence of Section 3.2.
32. Please change the word "begun" to "begin" in the 5th line of the second paragraph.
33. Please revise Section 3.2 to include greater detail regarding the gathering of the data
required to construct the groundwater model as well as the procedures to be used to
calibrate the model to the Site.
Section 3.4 MNA Ground-Water Monitoring Program and Data Analysis
34. Please revise the first sentence of the second paragraph of Section 3.4 to include
provisions for sulfide and carbon dioxide analyses.
Section 3.5 Transport and Attenuation Modeling
35. Please define the acronym "BTEX" in the third sentence of Section 3.5.
36. Please revise the first paragraph of Section 3.5 to detail the appropriateness of using
BIOSCREEN for evaluating the biodegradation of ethylene glycol at the Site. Please
detail how the utilization factors and/or the terminal electron acceptor (TEA) data will
- 5 -
• • be changed to account for ethylene glycol's physical and chemical characteristics as.
compared to benzene/ toluene/ethyl benzene (BTEX) compounds.
37. The last sentence of the first paragraph of Section 3.5 states that "Alternative
evaluation models described below will be used as well and therefore, if it appears
BIOSCREEN us not a useful tool, it will not be carried forward any further in the
analysis." Please revise Section 3.5 to include the evaluation criteria and procedures to
be used to determine if BIOSCREEN, or any other model, is an appropriate tool for the
Site. Additionally, alternative evaluation models were inadvertently omitted from the
document. Please correct this oversight.
38. The second paragraph of Section 3.5 indicates that the software package RT3D can
simulate a multitude of scenarios including natural attenuation processes or an active
rem.ediation for a variety of contaminants. This section further indicates that the users
_ can enter their own reaction kinetic expressions or choose from one of eight
preprogrammed reaction packages. Please detail the evaluation criteria and
procedures to be implemented to use this software for use at the Site.
Section 3.5 -Transport and Attenuation Modeling
39. First paragraph -still does not demonstrate that BIOSCREEN is appropriate for this
application. In addition, the last sentence of this paragraph references " .. Alternative
evaluation methods described below .. " but no alternatives are described.
40. Section 3.5, Page 13, Paragraph 1, BIOSCREEN Discussion:
2nd Sentence would be more convincing if its use need not be limited to BTEX
constituents instead of should not be limited to BTEX constituents.
3rd Sentence needs to indicate that the TEAs will be modified or the utilization factors
changed as indicated in the BIOSCREEN User's Manual and what those factors should
be given the data available for the application in which they want to use it.
4th Sentence needs to include information on what criteria will be used to determine
that BIOSCREEN is or is not a useful tool for this application, and then discuss what
other alternative evaluation models will be used instead or in conjunction with if
BIOSCREEN is a viable model.
Section 3.6 Mid-Project Data Review and Evaluation
41. Section 3.6 provides a general plan for the evaluation of the monitored natural
attenuation demonstration project. However, Section 3.6 does not provide adequate
detail as to how the evaluation will be conducted. Please revise Section 3.6 to provide
the criteria for evaluating the monitoring well network, criteria for evaluating the
groundwater flow modeling, the statistical analyses to be performed for the natural
attenuation data analysis, the criteria to evaluate the natural attenuation data, the
potential receptors, the human health and ecological risk criteria, break-down products,
the method for calculating the degradation rates (for all contaminants), etc. When
completed, this document should provide all the necessary information to conduct the
demonstration project and evaluate its success. Please correct these deficiencies.
- 6 -
• • 42. This section does not provide specific enough remedial goals or other criteria needed
to determine the effectiveness of the monitored natural attenuation remedy, such as
definitive benchmarks, or a "decision tree" for evaluating the performance of the MNA
demonstration. It is still too vague.
Section 3.7 Project Reporting and Schedule
43. A more definitive schedule is needed. How long after the sampling event will be
reports be submitted? Mid-project summary?
Table 3 Summary of Baseline MNA Monitoring Data
44. Please revise Table 3 to include the results of turbidity analyses.
45. Please correct Table 3 to indicate that the groundwater sample collected from
monitoring well Tl-1 contained 1.68 milligrams per liter (mg/L) DO and 276 millivolts
(mv) reduction-oxidation (redox) potential.
46. Please correct Table 3 to indicate that the groundwater sample collected from
monitoring well V-23 contained 6,430-micromhos per centimeter (mmhos/cm) specific
conductivity.
47. Please revise Table 3 to include the aerobic and anaerobic bacterial count for the two
equipment blank samples.
Table 5 Natural Attenuation Potential of Identified Constituents of Concern
48. Please revise Table 5 to include a reference or references for the conclusions reached
in Table 5.
Table 6 Summary of Annual Maximum Ethylene Glycol Concentrations
49. Please define the sample location "IT Cl" in Table 6.
Figure 6 Results of the MNA Sampling, Total Manganese
50. Please correct Figure 6 to indicate the correct isoconcentration contour line for the 10-
mg/L label and its associated leader line.
Figure 10 Proposed MNA Monitoring Locations
51. · Please revise Figure 10 to indicate the location of groundwater monitoring well F0 55.
Attachment 1 -Letter from Jerry Kubal, Kubal-Furr & Associates to Giezelle
· Bennett, EPA (July 11, 2001) ·
52. · Please revise the cover sheet for Attachment 1 to state, "Letter from Jerry Kubal,
Kubal-Furr & Associates to Giezelle Bennett, EPA (July 11, 2001 )."
- 7 -
• • Attachment 2 -Baseline MNA Field Sampling Logs
53. The Field Sampling Logs for extraction wells IT-2, IT-4, IT-6 and IT-7 were
inadvertently omitted from Attachment 2. Please correct this oversight.
April 19, 2002 Letter to Giezelle Bennett Re: Dioxane Sampling Results
54. This letter is inconclusive and difficult to follow. It appears to say that 1,4-dioxane was
present in groundwater, but that the highest concentration found (2.3 mg/I) is less than
the ecological toxicity screening value of 9.85 mg/I established by RUST, and less
than the RGOs of 3.58 mg/I and 2.57 mg/I for fish ingestion and child wading exposure
scenarios, respectively. Yet, the last two paragraphs of the letter discuss revisiting the
1,4-dioxane issues. If it was previously shown that the concentrations of 1,4-dioxane
are below the established screening levels and/or RGOs, what is driving the need to
re-evaluate at this point? What specifically does CNA have in mind? Will this
significantly alter and/or delay the final development and implementation of the work
plan? This needs to be clarified. ·
Comments from EPA's MNA expert:
55. After reading the report I have some concerns about 2 separate issues. The first is
the adequacy of this Work Plan. The second is the evaluation of the current Pump
and Treat system.
Comments on MNA Work Pla·n Adequacy
Overall the Work Plan is significantly deficient. The section discussing degradation of
ethylene glycol and Table 5 are helpful pieces in the Work Plan, but as a whole the
Work Plan requires considerable work. I have provided some direction below on what
EPA expects to see in the next revision. The site resides in a fractured rock
hydrogeologic setting which makes the hydrogeology of particular importance with
respect to predicting the plume attenuation and movement. Table 1 mentions "product
globules" which I interpret to be the possible presence of free product. This is an
aspect of the site that may complicate any MNA remedy for the site.
The discussion of Celanese MNA in Section 2.3 is not convincing without the data
below which would present the distribution vertically and with respect the other
physical and chemical site characteristics. The plan-view approach the PRP's are
taking is insufficient and does not prepare the way for the Work Plan. An evaluation of
the monitoring system and site _characterization to date is necessary to give credibility
to the conclusions drawn in Section 2.
I recommend that the PRP's consultants carefully read and implement the evaluation
presented in the EPA/600/R-98/128 September 1998 Technical Protocol for
Evaluating Natural Attenuation of Chlorinated Solvents in Ground Water. The current
iteration of the Work Plan indicates this has not been done thoroughly. The items
missing from this report that are particularly important are as follows:
1. Site hydrogeologic conceptual model
2. Site contaminant transport conceptual model
- 8 -
• • 3. Cross-sections of stratigraphy, aquifers, contaminant distribution, indicator
parameter distribution, well network, top of rock, fracture system and source
areas
4. Ground water potentiometric surface maps for several sampling events
5. Flownets for several sampling events
6. Basis for well placement and proposed monitoring using the above tools for
demonstration of adequacy
7. Discussion of pumping of extraction wells and supply wells on plume
geochemistry and geometry
8. Proposal to compare MNA to both an optimized pump and treat remedy and
other remedial alternatives
9. Evaluation of the adequacy of the current monitoring system to
a. Monitor plume distribution horizontally and vertically
b. Monitor plume movement horizontally and vertically
c. . detect changes in environmental conditions that may reduce the efficacy
of the intrinsic degradation processes
d. Detect new releases of contaminants
10. A detailed discussion of the source material for ground water contamination
and any remaining sources and avenues for transports such as lagoons, buried
utility corridors, heterogeneous fill material, old and existing sewer lines or
ditches or clay pipes, etc.
11. An evaluation of the contaminant source and changes from the time the
contamination first developed, removal or treatment actions taken at the site
and the flux of contamination out of the source over time
12. Discussion of Institutional Controls and water use changes that may occur
The above items are all important to a Work Plan because of the body of data that
already exists for the site. Building on this data set and using the data set to support
the activity the PRP's are proposing is essential. What becomes apparent in reading
through the Work Plan is that the PRP's consultants have not developed a conceptual
model for the site beyond some sampling of a few wells. The importance of the
conceptual model for both hydrogeology and contaminant transport is that each bit of
concentration data, hydraulic data, sampling field data, meteorological data, surface
water stage data, and waste disposal data is used as a line of evidence for the plume
distribution and ultimately the prediction of where and in what state the plume will end
up. An expansion of Section 1.3 is necessary.
The site hydrogeologic and contaminant transport conceptual model are also important
because the reason a remedial alternative change would be implemented is because
the original site/contaminant transport conceptual has changed. A detailed discussion
of this condition is critical to the Work Plan.
In Section 3.2 slug testing is proposed. It has long been known and documented that
slug tests are inadequate for determining aquifer properties. Slug tests are used in
instances where there is a lot of water to treat and no treatment system exists,
pumping of wells is not possible, or to preliminarily determine aquifer properties;
however, at Celanese pumping wells and a treatment system already exist. I suggest
that the pumping system be used to perform pumping tests to determine aquifer
properties to be used in the predictive modeling.
- 9 -
• • Add water quality parameters such as carbonate, bicarbonate, calcium, and sodium to
the parameter list. There appear to be surface water features associated with the site
and no mention is made of evaluating the impacts to these water bodies. Maps
showing the horizontal and vertical distribution of all the contaminants of concern at
the site should be presented with their concentration history.
No mention is made of the transformation products for ethylene glycol or other
compounds proposed for MNA. Transformation products should be established and
included in the sampling analytical list.
From the report it appears that only a subset of wells was selected for the baseline
monitoring. What are the details on how those wells were selected and why weren't
the remaining wells included? A map and construction details on all wells should be
included, along with the rational for their being omitted or included.
Is the flow system in bedrock understood. A map and detailed discussion of this issue
needs to be included in the report since additional monitoring points, such as surface
water locations, springs and seeps may need to be added to the monitoring system.
In a fractured rock setting often the primary flow path is the rubble zone that lies at the
interface to saprolite (at this site) and bedrock. II wells are screened above or below
the primary flow zone then an inaccurate view of attenuation processes can be
developed. Attenuation may be occurring around the wells, but not in the aquifer as a
whole. Since ethylene glycol is particularly mobile, it will be migrating swiftly is the
primary flow zones are well developed. In this case degradation reflected in the wells
may not be occurring and downgradient ground water flow is transporting undegraded
ethylene glycol.
The mid project review proposed in Section 3.6 is a good concept. The monitoring
well network and constituent list should be evaluated in the Work Plan too.
Evaluation of Existing Remedial System
Has the remedial system evaluation been performed? II not the PRP's should be
presenting that information with a rigorous locus on the adequacy of the well network, .
definition of contaminant source distribution and optimization of the pumping system. I
understand a Five Year Review was completed; but unfortunately the Five Year
Review is an administrative procedure that does not involve a detailed review of the
contaminant remedial process such as evaluation of pumping schemes, aquifer
properties and the impacts to the design. In addition to that detailed discussion and
quantification of the horizontal and vertical plume capture and development of
llownets and particle tracks should be included in the evaluation. Before the Pump
and Treat System is canned this sort of evaluation should be performed. A
comparison of the an MNA remedy with an optimized Pump and Treat is expected in
the final MNA report. Two good general guides to the evaluation is EPA/600/R-92/002
entitled General Methods for Remedial Operation Performance Evaluation and a
January 2002 document entitled Effective Management of Operation and Maintenance
for Pump and Treat Systems.
-10 -
• Conclusion
A great deal of work remains in order to produce a useful Work Plan. Demonstrating
monitored natural attenuation in a fractured rock setting where non-aqueous phase
liquid (NAPL) is present requires a particularly rigorous effort and to date not even a
moderate effort is reflected in the Work Plan.
All data should be submitted electronically in a database format so that independent
data analysis can be performed by reviewers. The submittal should include all the
historic ground water hydraulic, lithologic and contaminant concentration data.
Monitoring Well, extraction well and production or supply well construction details,
· surface water, soil and sediment sampling data, along with coordinates for each point,
should be included in the database.
-11 -
North Carolina A
Department of Environrnen~nd Natural
Resources
Michael F. Easley, Governor
William G. Ross Jr., Secretary
Dexter R. Matthews, Director
Ms. Giezelle Bennett
Remedial Project Manager
S uperfund Branch
Waste Management Division
US EPA Region N
61 Forsyth Street, I I th Floor
Atlanta, Georgia 30303
• &~?'A --_11,JL~ n rr: "f.,,,,,..,.....,.,._
MCDEMR
May 29, 2002
RE: Monitored Natural Attenuation Demonstration Project Work Plan
Celanese Corporation NPL Site
Shelby, Cleveland County, NC
Dear Ms. Bennett:
The Superfund Section of the North Carolina Department of Environment and Natural Resources
(NC DENR) has received and reviewed the Monitored Natural Attenuation Demonstration
Project Work Plan for the Celanese Corporation National Priorities List (NPL) Site. The
Superfund Section offers the following attached comments.
The Superfund Section of the NC DENR appreciates the opportunity to comment on this
document. If you have any questions or comments, please feel free to contact me at (919) 733-
2801, extension 349.
Attachment
:cvz,~~/!( 'EB. Mattison, CHMM
Environmental Engineer
NC Superfund Section
1646 Mail Service Center, Raleigh, North Carolina 27699-1646
Phone: 919-733---4996 \ FAX: [phone] \ Internet: vv,-vw.enr.state.nc.us
AN EQUAL OPPORTUNm' \ AFFIRMATIVE ACTION EMPLOYER -50% RECYCLED/ 10% po,,, CONSU~lER PAPER
Ms. Giezelle Bennett
May 29, 2002
Page I
• •
MONITORED NATURAL ATTENUATION DEMONSTRATION
PROJECT WORK PLAN
CELANESE CORPORATION NPL SITE
General
l. The Monitored Natural Attenuation Demonstration Project Work Plan simply addresses
the potential for degradation of ethylene glycol at the Celanese Corporation Site (Site).
However, the monitored natural attenuation (MNA) demonstration project must
demonstrate that all contaminants in excess of remedial goals will be naturally attenuated
to the satisfaction of all applicable, relevant and appropriate requirements as specified in
the Record of Decision. Please revise this document accordingly.
Table of Contents
2. Please revise the Table of Contents indicate that the title of Table 4 is "Summary of
Minimum/Maximum Concentrations of Selected MNA Parameters."
3. Please revise the Table of Contents to. indicate that the title of Table 6 is "Summary of
Annual Maximum Ethylene Glycol Concentration."
Section 1.1 Background
4. The last sentence of the first paragraph of Section 1.1 states "A site plan showing the
location of production areas, monitor wells, extraction wells, and other significant
features is shown on Figure I." Figure I simply indicates the location of the production
area and the wastewater treatment area. Please revise Figure 1 to include all monitoring
wells, piezometers, due diligence monitoring wells, all extraction wells, former source
area(s), surface water bodies including Buffalo Creek, and all other significant features of
the Site.
5. Section I .1 simply identifies the families of contaminants found at the Site. Please revise
Section 1.1 to quantify and depict the type and extent, both laterally and vertically, of
contamination found at the Site. Please revise the document to include the appropriate
tables and figures to describe the historical and current concentrations of contaminants at
the Site. Additionally, please revise the document to include a figure depicting the
historical and current potentiometric surface (i.e., pre-pumping conditions (if available)
and post-pumping conditions).
Ms. Giezelle Bennett
May 29, 2002
Page 2
•
Section 1.2 CERCLA Remedial Action Activities
•
6. Please clarify the meaning of the phrase "plugged back supply wells" as stated in the third
sentence of the second paragraph of Section 1.2.
Section 1.3 Monitored Natural Attenuation Demonstration Project
7. Please define the acronym "MCL" in the third sentence of Section 1.3.
8. Please delete the word "to" in the last sentence of the first paragraph of Section 1.3.
Section 2.1 Work Performed
9. The last sentence of the first paragraph indicates that the well rehabilitation program "was
expanded to include all monitor wells at the site, not just those which were part of the
MNA demonstration project." However, review of Table I and Table 2 indicates that the
piezometers, due diligence wells and Outer Tier/Inner Tier/PEW extraction wells were
not rehabilitated, including wells Tl-I, Tl-2, TD-3, and TD-4 which are part of the MNA
demonstration program. Please clarify this discrepancy.
10. The first sentence of the fourth paragraph of Section 2.1 states "All monitoring wells
were sampled using low flow purging and sampling procedures." However, review of
Table 2 the field sampling logs included as Attachment 2 indicates that the groundwater
monitoring wells were not purged a minimum of three well volumes in accordance with
Section 7 -Groundwater Sampling of the United States Environmental Protection
Agency (US EPA) Region N Environmental Investigations Standard Operating
Procedures and Quality Assurance Manual (EISOPQAM), May 1996. Additionally, the
field sampling logs indicate that the groundwater chemistry parameters (pH, specific
conductance, temperature and turbidity) were not allowed to stabilize prior to sampling
(particularly turbidity). Please revise Section 2.1 to include the criteria used to determine
purge adequacy. Additionally, please revise this document to ensure that all future
sampling activities are conducted in accordance with the US EPA EISOPQAM.
• •
Ms. Giezelle Bennett
May 29, 2002
Page 3
11. Please revise the last paragraph of Section 2.1 to discuss the potential impacts of turbidity
on the groundwater sampling and analysis performed. Results only met the performance
standard of IO Nephelometric Turbidity Units (NTUs) once, averaged approximately 87
NTUs across all wells (those that had.a well sampling log included in Attachment 2 with
the exception of extraction well IT-3), and the sample from extraction well IT-3
contained greater than 1,000 NTUs and was unable to be analyzed for sulfide and ferrous
iron concentration. Although the wells were redeveloped following surge blocking,
continued redevelopment, with pumping from the bottom of the wells to remove
accumulated silts and.sediments, may be necessary to reduce extremely high turbidity
levels. Please revise this document to address actions that may be taken in order to
achieve the desired turbidity standard.
Section 2.2 Summary of the Baseline MNA Sampling Data
12. The laboratory data quality assessment included in Attachment 3 and Attachment 4
indicate that missed holding times and equipment blank contamination contributed to the
most of the data qualifiers for this sample data package. Please revise Section 2.2 to
address these issues as well as the steps to be taken to prevent future occurrences.
Section 2.3 Evidence of Natural Attenuation
13. The second paragraph of Section 2.3 references an investigation performed at the Naval
Air Warfare Center in Lakehurst, New Jersey, in which biological techniques were used
to remediate groundwater contaminated with ethylene glycol. However, the
concentrations of ethylene glycol were an order of magnitude less than those encountered
at the Site. Additionally, this paragraph indicates that the groundwater was extracted,
treated, re-injected and further treated with the addition of mineral nutrients and oxygen.
The scope of work for this project is to determine the potential of the contamination to
naturally attenuate. Please revise this section to include an explanation of the relevant
results of this investigation, including, but not limited, to the mechanism(s) for
attenuation, the conditions necessary for degradation, the byproducts of degradation, etc.
Additionally, please revise the document to include an attachment with a synopsis of the
investigation at the Naval Air Warfare Center site.
I 4. The first sentence of the fourth paragraph of Section 2.3 states "Ethylene glycol is readily
biodegradable under both aerobic and anaerobic conditions." Please include a reference
for this statement. Additionally, please include a synopsis of the study used to reach this
conclusion as an attachment to this document.
.... _...,..
Ms. Giezelle Bennett
May 29, 2002
Page 4
• •
15. Please revise the seventh paragraph of Section 2.3 and appropriate sections of the
remainder of this document to include provisions for using an analytical technique that
can measure the full range of dissolved iron concentrations as suggested by Dr. Robert
Borden.
16. The last sentence of the tenth paragraph of Section 2.3 indicates that sulfate
concentrations decrease as ethylene glycol concentrations increase. However, the table
included in Section 2.3 does not support this hypothesis. The eighth paragraph of Section
2.3 and Dr. Robert Borden's data analysis report included as Attachment 5 indicate that
very high ethylene glycol concentrations may inhibit or slow the rate of sulfate reduction
or produce interferences in the sulfate measurement technique. Please revise Section 2.3
to eliminate these inconsistencies.
17. The last sentence of the eighth paragraph of Section 2.3 states that "Subsequent sampling
events will incorporate quality assurance checks in an attempt to resolve/quantify the
sulfate interferences." Please revise this section and appropriate sections of the remainder
of this document to specify precisely what and how the quality assurance checks are to be
performed (i.e., Dr. Borden's suggestion of spiking solutions of known sulfate
concentrations with ethylene glycol).
18. Section 2.3 does not discuss the results of dissolved oxygen (DO) analysis. Please revise
Section 2.3 to include a discussion of the DO results, causes of the irregularities,
sampling methods, equipment calibration, and methodologies to prevent future issues
with sampling equipment or the introduction of oxygen to the sample/aquifer.
19. The third sentence of the eleventh paragraph of Section 2.3 identifies the information
required to conduct any form of remediation, whether it is active or passive. Please revise
this document to identify the remedial objectives of the monitored natural attenuation
demonstration, the potential receptors, the distance {buffer zone) between the plume and
the receptors, and the ethylene glycol degradation rate. Groundwater modeling with zero
biodegradation rates should also be performed to demonstrate that sentinel wells would
detect the presence of contaminants such that remedial measures could be taken to
mitigate the spread of contamination and prevent the uptake of contaminants by the
receptors.
Section 3.2 Ground-Water Flow Rate Analysis
20. Please correct the spelling of the phrase "hydraulic characteristics" in the second sentence
of Section 3.2.
Ms. Giezelle Bennett
May 29, 2002
Page 5
• •
21. Please revise Section 3 .2 to include greater detail regarding the gathering of the data
required to construct the groundwater model as well as the procedures to be used to
calibrate the model to the Site.
Section 3.4 MNA Ground-\Vater Monitoring Program and Data Analysis
22. Please revise the first sentence of the second paragraph of Section 3.4 to include
provisions for sulfide and carbon dioxide analyses.
Section 3.5 Transport and Attenuation Modeling
23. Please define the acronym "BTEX" in the third sentence of Section 3.5.
24. Please revise the first paragraph of Section 3.5 to detail the appropriateness of using
BIOSCREEN for evaluating the biodegradation of ethylene glycol at the Site. Please
detail how the utilization factors and/or the terminal electron acceptor (TEA) data will be
changed to account for ethylene glycol's physical and chemical characteristics as
compared to benzene/ toluene/ethyl benzene (BTEX) compounds.
25. The last sentence of the first paragraph of Section 3.5 states that "Alternative evaluation
models described below will be used as well and therefore, if it appears BIOSCREEN us
not a useful tool, it will not be carried forward any further in the analysis." Please revise
Section 3.5 to include the evaluation criteria and procedures to be used to determine if
BIOSCREEN, or any other model, is an appropriate tool for the Site. Additionally,
alternative evaluation models were inadvertently omined from the document. Please
correct this oversight.
26. The second paragraph of Section 3.5 indicate that the software package RT3D can
simulate a multitude of scenarios including natural attenuation processes or an active
remediation for a variety of contaminants. This section further indicates that the users
can enter their own reaction kinetic expressions or choose from one of eight
preprogrammed reaction packages. Please detail the evaluation criteria and procedures to
be implemented to use this software for use at the Site.
Ms. Giezelle Bennen
May 29, 2002
· Page 6
•
Section 3.6 Mid-Project Data Review and Evaluation
•
27. Section 3.6 provides a general plan for the evaluation of the monitored natural attenuation
demonstration project. However, Section 3.6 does not provide adequate detail as to how
the evaluation will be conducted. Please revise Section 3.6 to provide the criteria for
evaluating the monitoring well network, criteria for evaluating the groundwater flow
modeling, the statistical analyses to be performed for the natural attenuation data analysis,
the criteria to evaluate the natural attenuation data, the potential receptors, the human
health and ecological risk criteria, the method for calculating the degradation rates (for all
contaminants), etc. When completed, this document should provide all the necessary
information to conduct the demonstration project and evaluate its success. Please correct
these deficiencies.
Table 3 Summary of Baseline MNA Monitoring Data
28. Please revise Table 3 to include the results of turbidity analyses.
29. Please correct Table 3 to indicate that the groundwater sample collected from monitoring
well TI-I contained 1.68 milligrams per liter (mg/L) DO and 276 millivolts (mv)
reduction-oxidation (redox) potential.
30. Please correct Table 3 to indicate that the groundwater sample collected from monitoring
well V-23 contained 6,430-micromhos per centimeter (µmhos/cm) specific conductivity.
31. Please revise Table 3 to include the aerobic and anaerobic bacterial count for the two
equipment blank samples.
Table 5 Natural Attenuation Potential of Identified Constituents of Concern
32. Please revise Table 5 to include a reference or references for the conclusions reached in
Table 5.
Table 6 Summary of Annual Maximum Ethylene Glycol Concentrations
33. Please define the sample location "IT Cl" in Table 6.
Ms. Giezelle Bennett
May 29, 2002
Page 7
• •
Figure 6 Results of the MNA Sampling, Total Manganese
34. Please correct Figure 6 to indicate the correct isoconcentration contour line for the I 0-
mg/L label and its associated leader line.
Figure 10 Proposed MNA Monitoring Locations
35. Please revise Figure IO to indicate the location of groundwater monitoring well F-55.
Attachment 1 Letter from Jerry Kubal, Kubal-Furr & Associates to Giezelle
Bennett, EPA (July 11, 2001)
36. Please revise the cover sheet for Attachment I to state, "Letter from Jerry Kubal, Kubal-
Furr & Associates to Giezelle Bennett, EPA (July 11, 2001)."
Attachment 2 Baseline MNA Field Sampling Logs
37. The Field Sampling Logs for extraction wells IT-2, IT-4, IT-6 and IT-7 were
inadvertently omitted from Attachment 2. Please correct this oversight.
• • UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
\
REGION 4
ATLANTA FEDERAL CENTER
61 FORSYTH STREET
ATLANTA, GEORGIA 30303-8960
MEMORANDUM
DATE:
SUBJECT:·
FROM:
TO:
May 8, 2002 ·
Celanese NPL Site
Shelby, NC
Giezelle S. Benn,eJ:-7(/'() ,
Remedial Proje(~nir
Reviewers
Elmer Akin, OTS
David Mattison, NC DENR _
John Blanchard, B&V
Attached is the Monitored Natural Attenuation Demonstration Project Work Plan,
dated April 29, 2002 for the Celanese Site in North Carolina. Please review it and send
any comments that you have to me no later than May 24, 2002.
If you have any questions, please give me a call at 404-562-8824. Thank you
for your assistance in this matter.
lnt0met Address (URL)• http://www.epa.gov
Aecycled/flecyc1able "Printed with Vegetable OH Based Inks on Recyded Paper (Minimum 30% Postconsumer)
• Kubal-Furr & Associates •
Post Office Box 273210
Tampa, FL 33688-3210
813/265-2338
F AX/265-3649
[e-mail]
Ms: Giezelle S. Bennett
U.S. Environmental Protection
Agency, Region IV
61 Forsyth Street
Atlanta, GA 30303
Environmental Management Services
April 19, 2002
Post Office Box 8024 7
Simpsonville, SC 29680-0247
864/962-9490
FAX/962-5309
[e-mail]
Re: Dioxane Sampling Results/Ticona-Shelby (FKA: Celanese Fiber
Operations)
Dear Ms. Bennett:
On behalf of CNA Holdings, Inc. and Ticona, I have been asked to prepare this letter report
summarizing the results of recent data collection activities related to ground-water sampling for
1,4-dioxane. Prior to your assuming the RPM responsibilities for Ticona-Shelby site, a due
diligence investigation was conducted which included installation of monitor wells, ground-water
sampling, soil sampling, sediment sampling and surface water sampling. This work was
performed in June-July of 1998 by Fluor Daniels on behalf of KoSa, the prospective buyer, with
Kubal-Furr & Associates representing Hoechst Celanese (now CNA Holdings, Inc.) in an
oversight capacity.
A part of the due diligence investigation included analyzing selected samples for the presence of
1,4-dioxane. 1,4-Dioxane was reported as present only in ground-water samples and only in
samples collected from monitor wells and the Outer Tier extraction wells, all of which were located
downgradient of the polishing ponds. No 1,4-dioxane was reported in the main area of the plant in
any existing monitor wells sampled nor in the new wells installed during due diligence. Further, no
l ,4-dioxane was reported as present in any of the soil samples, sludge samples, sediment sample,
polishing pond sample, or clarifier effluent sample.
The due diligence sampling for 1,4-dioxane was later supplemented with a confirmatory
sampling event from the monitor wells and Outer Tier extraction wells. The confirmatory sampling
was conducted in September of 1998 by Kubal-Furr & Associates. The results of the due diligence
and confirmatory sampling showed comparable results for 1,4-dioxane and these data were
discussed in a conference call on October l, 1998 with the EPA (Mr. Ken Mallary) and DENR
(Mr. Bruce Nicholson). The due diligence and confirmatory sampling data for 1,4-dioxane were
later summarized in a letter report to Mr. Mallary dated October 27, 1998, with copies to Mr. Bruce
Nicholson with the DENR Superfund Branch and Ms. Charlotte Jesnick with the DENR Inactive
Hazardous Sites Branch. There were no specific actions identified to be taken at that time.
In planning for the routine 3rd Quarter 2001 CERCLA ground-water .sampling and the
monitored natural attenuation (MNA) baseline sampling, CNA requested that Kubal-Furr expand
the sampling matrix with additional sitewide sampling that included an updated confirmatory and
expanded 1,4-dioxane assessment. CNA has not received any response to its October 27, 1998
• •
Ms. Giezelle Bennett - 2 -April 19, 2002
1,4-dioxane letter report and conducted the updated sampling as a voluntary measure to assess any
changes in configuration or migration of 1,4-dioxane in the ground water. This sampling was
conducted during September of 2001.
Figure 1 shows the Shelby facility and the locations of monitor wells and surface water sites
sampled for 1,4-dioxane. A summary of the 1,4-dioxane data for the September 2001 sampling
event is presented in Table 1, while Table 2 compares the due diligence (June-July 1998),
confirmatory sampling (September 1998) and most recent sampling (September 2001) results for
. 1,4-dioxane. While the set of sample locations with multiple analyses is relatively small at this
point, for the most part, Table 2 shows the 1,4-dioxane concentrations reported in 2001 to be
consistent with the 1998 results.
The higest reported concentration of 1,4-dioxane in the most recent sampling event was at
monitor well V-23 adjacent to the former source area remediated as part of OU-2. The former
source area was not "clean closed" during OU-2 remedial activities and the residual ground-water
contamination existing in this area is not unsuspected and was the basis upon which the Inner Tier
extraction well system was installed. Although residual ground-water contamination exists, this is
the first indication of 1,4-dioxane reported at the former source area.
As you know, CNA implemented a voluntary initiative to provide the residents in areas east
and downgradient of the plant with county water during 1995. As part of this initiative, the
property owners allowed CNA to plug back any wells used for domestic supplies and to place deed
restrictions on the property intended to prevent any future well drilling in the area. In July of 2001,
as part of recommendations made in the EPA's Five Year Review Report, Kubal-Furr assisted
CNA in confirming that these deed restrictions had been recorded and also conducted a field survey
and spot check to assure that the residents were still connected to the county water system. This
survey was expanded to the parcels northeast of the plant in November of 2001 and it was
determined that all adjacent properties are hooked up to the Cleveland County water system.
In the October 27, 1998 letter report to the agencies, a risk discussion was included to assist in
evaluating the need to resume pumping from the Outer Tier extraction wells which had been shut as
part of a partial delisting petition approved in February of 1998. This discussion concluded that the
1,4-dioxane, in the concentrations reported as present, did not represent an unacceptable risk to
either a fisherman who eats fish caught in an adjacent creek nor to a child who lives in the vicinity
and regularly wades in the creeks. Human consumption of ground water was not considered a
complete exposure pathway because the residents had been provided county water for potable
purposes.
The risk discussion presented in October of 1998 was based in part on a draft risk assessment
document prepared in 1987 for the CNA Salisbury, NC facility by RUST Environment and
Infrastructure. This document, finalized in November of 1998, was recently reviewed by Kubal-
Furr and it was determined that the 1,4-dioxane risk-related numbers did not change from the draft
to the final document.
RUST evaluated the potential toxicity to aquatic organisms (including benthic organisms) of
1,4-dioxane in surface water and derived a toxicity screening value of 9.85 mg/L. Considering
potential human receptor pathways, RUST developed remedial goal options (RGOs) for a
fisherman who eats fish caught in an adjacent creek and a child who lives in the vicinity and
regularly wades in the creek. The RGOs for the fish ingestion and child wading scenarios were
Kubal-Furr & Associates
• •
Ms. Giezelle Bennett -3 -April 19, 2002
3.58 mg/Land 2.57 mg/L, respectively. Comparing the highest reported 1,4-dioxane results from
Shelby with·the RGOs and toxicity screening values developed by RUST would indicate that 1,4-
dioxane does not represent an unacceptable human health or ecological risk at the concentrations
reported.
Revisiting the risk discussion in the context of the current 1,4-dioxane findings, from a human
consumption standpoint, the July and November 2001 property survey concluded that residents
surrounding and downgradient of the facility are on the Cleveland County water system and this is
not considered a complete exposure pathway.
CNA is presently evaluating options and is in the process of formulating a plan specifically
addressing 1,4-dioxane issues. We would propose scheduling a meeting with your office and the
DENR, at a convenient time and place, to review these findings and to discuss the options and
approach to dealing with these issues. I'll call you within the next week to discuss possible
meeting dates. In the meantime, feel free to contact me at 813.265.2338 if you have any questions
after you've had a chance to review this information.
Sincerely,
Kubal-Furr & Associates
.Jtf-w___
Jerry ,E. Kubal, P .G.
North Carolina License #212
cc: Grover Nicholson, NC DENR ✓
Steve Olp, Celanese Americas
PEM Carter, Ticona-Shelby
Everett Glover, EarthTech
Kubal-Furr & Associates
• •
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
4WD-NSMB
Mr. Steve Olp
Sr. Remediation Manager
Celanese Americas Corp.
2300 Archdale Dr.
P.O. Box 32414
Charlotte, NC 28232
SUBJ: Celanese NPL Site
Shelby, NC
Dear Mr. Olp:
REGION 4
· ATLANTA FEDERAL CENTER
61 FORSYTH STREET
ATLANTA, GEORGIA 30303-8960
March 26, 2002
r··· ···-·-
The Environmental Protection Agency has reviewed the March 8, 2002 response
to comments on the Monitored Natural Attenuation Work Plan. Further clarifications
are requested on a few of the responses. Please submit a revised work plan that
incorporates all comments to the Agency no later than April 16, 2002.
If you have any questions, please give me a call at 404-562-8824.
~~liU-'
· cJ;zelle S. Bennett
Remedial Project Manager
cc: Grover Nicholson, NC DENR
John Blanchard, B&V
Jerry E. Kubal, Kubal & Furr
Internet Address (URL) • http://www.epa.gov
Recycled/Rocyclable • Ptinlod with Vegolablo OH Based Inks on Aecydod Paper {Minimum 30% Poslconsumer)
·1 ION
• •
. COMMENTS
MARCH am RESPONSE TO COMMENTS
MONITORED NATURAL ATTENUATION WORK PLAN
1. The response to Comment #1 does not discuss the use of a "decision tree" or
offer to provide specific criteria for evaluating the progress/effectiveness of the
MNA demonstration project. It does not specifically answer the comment.
2. Comment #12 does not have a response.
3. For Comment #14, a brief paragraph will suffice.
4. Comment #21: Please see section 7.2 -Groundwater Sampling -Purging in the
EPA SOP for a discussion on the 10 NTU turbidity guideline. Furthermore, the
report needs to explicitly state that if 10 NTUs cannot be achieved, then it will be
noted in the sampling report and the impact on the results will be discussed.
5. Comment #26. Please briefly summarize what these reports found, and include
the information in the work plan.
6. Comment #27. The response mentions supplementary treatment methods that
may be used to enhance the biodegradation process. Please include these in
the decision process and also address them at the "mid-point" evaluation. A
paragraph description on each method should be included.
7. Comment #35 -BIOSCREEN can be used if a demonstration is made that it can·
be applied to the ethylene glycol MNA case. The response mentions changing
the utilization factors in accordance with the BIOSCREEN user's manual.
Please demonstrate that this is applicable to the current situation. If not, go to
alternative models (as mentioned in the comment response).
8. Comment 37. Provide data summaries only. Note in the workplan that the entire
QNQC package is available upon request.
• Kubal-Furr & Associates •
Environmental Management S;rvices
Post Office Box 273210
Tampa, FL 33688-3210
813/265-2338
FAX/265-3649
[e-mail]
Ms. Giezelle S. Bennett
U.S. Environmental Protection
Agency, Region IV
61 Forsyth Street
Atlanta, GA 30303
March 8, 2002
Re: Response to MNA Work Plan Comments
Dear Ms. Bennett:
Post Office Box 80247
Simpsonville, SC 29680-0247
864/962-9490
FAX/962-5309
kfagv@ix.11ct_com.com
I... \\ ~;; ;,: :~
l : [ rr; }', \\ ,' l' ~•_I; \ \ \\:Ji_ r ,. : . \\\ 1J
\ , ('• \.At>-tl 1 4 2002 , ~-:
\') . . \
On behalf of CNA Holdings, Inc. and Ticona, I have been asked to prepare this response to
comments received from the EPA on January 30, 2002 concerning the "Monitored Natural
Attenuation Demonstration Project Work Plan" which was prepared by Kubal-Furr and submitted
to the agency on December 21, 2001. These responses also incorporate items discussed in a
conference call on February 15, 2002 between yourself, John Blanchard of Black & Veatch, Jim
Furr of Kubal-Furr and myself.
I felt the easiest way to address these items was to include your complete comment letter and
provide a response following each comment, which is the format followed in the attachment. Most
of these responses are general in nature, describing how we propose to deal with the comments in
a revised work plan. My suggestion would be that on the next go-round, we provide a revised
draft MNA work plan for review which incorporates specific text and changes necessitated by the
comments. This is the only way to see how this whole thing will hang together and would seem to
be more productive for both parties.
Please give me a call (813.265.2338) after you've had a chance to review this information and
we can discuss how to proceed from here.
Sincerely,
Kubal-Furr & Associates
dlf~e__
Jerry 1E. Kubal
cc:•Grover Nicholson, NC DENR
Steve Olp, Celanese Americas
Pem Carter, Ticona-Shelby
Everett Glover, EarthTech
• •
COMMENTS
MONITORED NATURAL ATTENUATION DEMONSTRATION
PROJECT WORK PLAN DATED DEC 2001
General
1.Borden's report seems to offer sufficient evidence that natural attenuation of the
ethylene glycol is occurring. The workplan properly explains which
groundwater parameters will be measured from which wells and that the data
will be pl\Jgged into acceptable transport and attenuation models. However, it
is unclear exactly how Ticona plans to demonstrate that natural attenuation is
truly occurring. For instance, will a steady decrease in the concentrations of
ethylene glycol and a corresponding increase in, say, the concentrations of
methane be sufficient information to bless continued MNA as the remedy? It
may be a bit premature for this decision, (maybe we need to see some data
and analyses first) but all parties (EPA, NC, and Ticona) should understand the
rules.
(We would consider success to be a reduction in concentration of the ethylene
glycol and other amenable constituents, increases in the constituents indicative
of attenuation and ground-water releases controlled [i.e., no migration of the
"plume'1-As discussed in our conference call, the quarterly data will be
submitted to the agency in tabular and graphical form and after four quarters of
monitoring an expanded document will be prepared to discuss findings, initial
indications of success and any mid-course revisions to the plan/approach that
would improve the likelihood of success. Because of the expected "rebound" in
selected constituent concentrations following Inner Tier shut down, the baseline
for evaluation purposes will be the first set of samples collected after the Inner
Tier wells are turned off rather than the initial samples collected last September.
The September data set was useful for the work plan and provided an
indication of on-going attenuation but not necessarily a benchmark by which to
judge success.)
Section 1.1 -Background
2.The name of the Site should be consistent despite its change in ownership. This
site is designated on the National Priorities List as the Celanese Fiber
Operations Site or "Celanese". By using this name, there will be no doubt as to
the site in which this document refers. Please replace "Shelby" with
"Celanese" throughout the document.
(The site is listed in the CERCLIS database as the Celanese Fiber Operations
1
• •
site. We can title the work plan that way and put CNA Holdings, lnc./Ticona in
parentheses beneath it on the title page. The ownership changes uld be
discussed in the background section as they are now but the site would be
referred to in the text as the CFO site)
3.The first paragraph should include a description of the CERCLA-related
manufacturing activities that took place at the site.
(There were no "CERCLA-related" manufacturing activities per se. There were
manufacturing activities that took place prior to the NPL listing and we will
provide a brief description of these manufacturing activities)
4.Features on Figure 1 referenced in the first paragraph are not labeled. Label all
pertinent features on Figure 1.
(Figure will be changed)
5.Provide a general description of what types of investigation activities have been
ongoing since 1981 and their results. What were the Contaminants of
Concern and the contaminant concentrations found? What were the cleanup
levels? What media were contaminated and to what depths?. What is the
general hydrogeology in the area? Which way is the groundwater flowing?
This information does not have to be in great detail, but it should provide the
reader with a more detailed understanding of what has been done at the site,
what the results were, and what the cleanup standards are.
(We will provide a brief summary/overview of site conditions extracted from
earlier reports.)
6.Delete the 3rd sentence in the 2nd paragraph. All work is voluntary.
(The text will be changed)
7. Delete the word 'later' in the 4th sentence of the 2nd paragraph.
(The text will be changed)
a.Define "RD/RA in the 4th sentence.
(Remedial Design/Remedial Action. The text will be changed.)
Section 1.2 -CERCLA-Related Activities
9.This section may be more appropriately designated "CERCLA Remedial Action
2
• •
Activities" to clearly distinguish the discussion on the long-term remedial action
process as opposed to the previously discussed CERCLA investigation
activities.
(The section title will be changed)
10.Discuss why the OU2 and the Outer Tier of Operable Unit 1 were delisted.
Discuss, briefly, the reasoning for the partial delisting.
(We will include a paragraph from the de/isling petition and/or Federal Register
Notice)
11.The first paragraph on page 2 notes that the Outer Tier is being maintained in
"stand-by status." Briefly describe the activities that are being performed to
keep this system in a "stand-by status" (i.e. periodic maintenance checks,
etc.).
(We will include a description of the monthly and quarterly maintenance checks
that are performed at the Outer Tier. These are also provided in the routine
semiannual reports.)
12.Without a discussion of the entire system, mentioning the SBR is out of context.
Either delete it or briefly describe the process.
Section 1.3 -Monitored Natural Attenuation Demonstration Project
13.Please do not cite a draft report.· If requested under the Freedom of Information Act
(FOIA), EPA would not be able to release it. Facts and information can be used
from the report without citing it.
(We will modify the text to remove references to the draft report.)
14.Be more specific in explaining your rationale for this MNA demonstration project.
Expand the discussion to include information such as the contaminants being
evaluated, their initial concentrations, their "final" concentrations (at the point
where it was determined that the pump and treat system may not be effective),
and the applicable cleanup standards. Explain why the current system isn't as
effective as it should be.
(We will reference the July 2001 letter to Giezelle Bennett in which we
elaborated on all these issues. This letter will be included as an attachment. A
copy is also a/teched to these responses for John Blanchard's review.))
15.The bullets at the bottom of page 2 discuss only two of the five recommendations
3
• •
made by the EPA in their Five-Year Review Report. Discuss how you will
implement the.other three recommendations: a) Decreasing the detection
limits for groundwater analytes to the contract required quantitation limits; b)
Increase the quantity of wells sampled to ensure that the plume remains
exclusively on the plant property; and c) Periodic reconnaissance of the
downgradient area to determine if any new drinking water supply wells have
been installed.
(Outside the context of the Five-Year Review recommendations, these issues
are unrelated. It was decided in our conference call to respond to these issues
separately, not in the MNA work plan.)
16.ln the last sentence of the 1st paragraph, change "appears likely" to "may".
(The text will be changed)
17.ln the last paragraph, change" ... is presented below" to" ... is presented in Section
2".
(The text will be changed)
Section 2.1 -Work Performed
18.lnclude a figure which indicates the wells which were surged and redeveloped.
Figure 3 could be used for this purpose by including which wells were
developed, but not sampled.
(We will show the wells in the figure and include a table which summarizes the
activities taken at each well.)
19.A record of exactly what was done to each of the 49 wells in the rehabilitation
program should be included as an appendix.
(See response to Comment 18)
20.An identification of the background extraction/monitoring wells sampled would be
helpful to the reader in the evaluation of the work plan. A table of well
construction information including well depths and screened interval lengths
and depths is also needed. Additionally, an explanation of why several wells
were redeveloped, but not sampled, is needed.
(We will provide a table which summarizes well construction details and add
text to indicate why some wells were developed but,not sampled for MNA
purposes.)
4
• •
21.The final turbidity is well above the EPA-recommended 10 NTUs. Please provide
an explanation as to why the guidelines were not followed and what effect, if
any, this had on the final analyses.
(We did follow the EPA SOPs for /ow-flow sampling although we don't see 10
NTUs listed as a specific criteria to assess whether a we// has stabilized and
can be sampled. We agree sampling wells above 10 NTUs is undesirable and
we will evaluate ways in which we can improve the quality of the collected
sample or possibly eliminate/substitute some problem wells. As an aside, it
appears that the turbidities have improved considerably based on work done in
February_ for the routine semiannual sampling event.)
Section 2.2 -Summary of MNA Sampling Data
22.lntroduce a new sentence in paragraph 2 introducing Figures 4, 5, 6, 7,8, and 9 to
give the reader a visual conception of the presence of the parameters analyzed
and tabularized previously in this section of the work plan.
(Text will be added to the revised work plan introducing these figures.)
23.Ethylene glycol is clearly the most prevalent contaminant, but what about the other
contaminants of concern, especially the VOCs?
(We will provide a summary table listing all constituents reported as present
near the former source area and an indication as to whether or not they are
amenable to attenuation.)
Section 2.3 -Evidence of Natural Attenuation
24.ln the 2nd paragraph, indicate in a new sentence that DO results, however, were
inconclusive which is likely due to potential oxygen introduction from the
atmosphere during sampling. Also indicate how this potential sampling
problem will be eliminated in future sampling of DO.
(We will include narrative in the revised work plan on this issue.)
25.ln the 3rd paragraph, insert a sentence or two after current 2nd sentence indicating
how the extent of iron being used as an electron acceptor is not known at the
site due to the 10 mg/L upper detection limit of the ferrous iron test used;
however kits are not available above 1 O mg/L, therefore, its analyses will be
limited to determining the presence or absence of ferrous iron up to 10 mg/L
as opposed to better quantifying the amount of ferrous above that amount.
Ferrous iron must be determined quickly after sample collection limiting the
5
• •
means of analysis to field analysis. Delete the rest of the current 3rd sentence
following "inconclusive" and add the following "as to why there is an increase in
sulfate when ethylene glycol is greater than 1000 mg/L. One possibility is that
very high ethylene glycol concentrations slow or inhibit sulfate reduction. A
second possibility is that high ethylene glycol concentrations interfere with the
sulfate measurement technique. Future sampling analysis will include spiking
samples of known sulfate concentrations with ethylene glycol to determine if
there is an interference in the analytical technique."
(We are not aware of a Hach ferrous iron field test kit [i.e., the ones
recommended by USEPAJ having maximum detection limits greater than
10ppm bµt will continue to check. According to MNA protocols (USEPA 1996),
the presence of ferrous iron greater than 1 ppm suggests: (1) the contaminant
plume has impacted the biogeochemical conditions and utilized Fe3+ to
produce Fe2+; and, (2) a reductive pathway is possible. To look at the big
picture and evaluate the "potential" of MNA, a 10ppm or higher accumulation of
Fe2+ should be sufficient to determine if iron-reducing conditions are occurring.
Alternately, if ferrous iron continues to be an issue we would propose looking at
an alternate constituent such as manganese, one for which we do not have the
analytical detection problems.
With regard to the sulfate, Davis & Floyd Laboratories suggested the possibility
of a sulfate interference problem. We will work with the lab to incorporate QA
checks in subsequent sampling events during the MNA demonstration to
resolve/quantify the sulfate concerns. )
26.Cite other instances where monitored natural attenuation has been effective for
ethylene glycol. Cite specific reports, research which has been done.
("Bioremediation of Ethylene Glycol-Contaminated Groundwater at the Naval
Air Warfare Center in Lakehurst, New Jersey," 1994, by Paul E. Flathman and
Lucy S. Bottomley. Chapter 23, pp 491-500, in: Bioremediation Field
Experience, Flathman, Paul E., Jerger, Douglas E., and Exner, Jurgen H., Eds.
This article also contains numerous cross references to ethylene glycol
degradation.)
27.Why is MNA alone being considered? Could this be supplemented to accelerate
the natural attenuation process? For example, would pumping nitrogen,
phosphate, and oxygen-saturated water into the contaminated areas accelerate
the process? (Ref: Flatman, PE, Jerger, DE, Bottomley LS (1989),
"Remediation of Contaminated Ground Water using Biological Techniques.
Ground Water Monitoring Review, 9:105-119).
(Ethylene glycol is determined to be biodegradable under both aerobic and
6
• •
anaerobic conditions. MNA is being considered because ethylene glycol is
biodegradable and MNA parameters indicated the biological activities at the
site can support degradation by using ethylene glycol as an electron donor and
organic substrate. The addition of nutrients and oxygen-saturated water or an
oxygen release compound can enhance the degradation of ethylene glycol
because aerobic conditions are always energetically-favorable for bacteria.
However, before deciding to add oxygen, consideration needs to be given to
what the remedial objectives are; where the final receptors are; what the
distance (buffer zone) is between the plume and final receptors; and, the
ethylene glycol degradation rate . The addition of oxygen or other amendments
can always be considered if ethylene glycol needs to be remediated at a faster
rate.)
28.ln summary, discuss historical research and implementation of natural attenuation
for ethylene glycol. Discuss enhancements to MNA that may accelerate the
process.
(See response to Comment 27.)
29.This section needs a table that shows the maximum ethylene glycol
concentrations from each year.
(An ethylene glycol search of the database will be performed and these data
will be included in the revised work plan.)
Section 3.1 -Inner Tier Extraction System Shut-down
30.Baseline data collected in September 2001 under pumping conditions will not
likely reflect site conditions in the 1st quarter of 2002 when pumping is ·
discontinued. Ethylene glycol concentrations will likely go up as a result of
rebound, changing the baseline conditions established in the September 2001
analytical results. Therefore, new baseline data may be needed to generate
"current" conditions.
(We agree that the first set of samples collected under non-pumping conditions
will be the baseline as far as our evaluation criteria are concerned. See also
discussion under comment 1 above.)
Section 3.2 -Ground Water Flow Rate Analysis
31.What constitutes aquifer testing? Provide specific methods and procedures.
Describe method procedures for slug testing.
(We will provide a narrative discussing the proposed aquifer testing methods)
7
•
Section 3.4 -MNA Monitoring Program and Data Analysis
32. Include Monitor Well F-55 in the first bullet.
(The text will be changed to include F-55)
33.lnclude ferrous iron in the field analysis.
•
(Ferrous iron will be added to the list of field parameters. See also the
discussion under comment 25 above.)
34.When providing data to the EPA and the State of North Carolina, include graphics
showing the indicator chemical plumes, the ethylene glycol plume, and include
tables which track the indicator chemical and ethylene glycol concentrations
over time at each monitoring well. Including graphics will be more
user-friendly.
(Comment refers to future data submittals. We will provide the data in the
suggested format)
Section 3.5 -Transport and Attenuation Modeling
35.BIOSCREEN is a computer model which simulates natural attenuation
remediation of dissolved hydrocarbons at petroleum fuel release sites. No
connection between ethylene glycol and BIOSCREEN were detected during an
internet search. Suggest either showing verification that BIOSCREEN is
applicable here or looking into using another computer model.
(Bioscreen is based on an analytical solute transport model and is designed to
adequately screen the MNA potential by providing TEA (i.e., 02, nitrate, ferrous
iron, sulfate, methane), contaminant concentrations and kinetic rate
information. Bioscreen is commonly used to model BTEX transport but its use
should not be limited to BTEX constituents. When constituents other than BTEX
are modeled, the utilization factors need to be changed or the TEAs should be
provided accordingly to reflect utilization factors (Bioscreen User's Manual).
Ethylene glycol, a C2 compound with 2 hydroxylic groups and solubility of
>=10g/100mL, should be suitable for the use of Bioscreen. However, Because
we have proposed alternative evaluation models as well, if BioScreen doesn't
appear useful, we'll just drop it.)
Section 3.6 -Project Reporting and Schedule
36.Suggest that the report include other recommendation(s) such as additional
8
• •
monitoring in the event that a recommendation for permanent shut-down of the
Inner Tier Extraction and Treatment System is not warranted. Look into other
potential remedies per EPA's recommendation in their Five-Year Review
Report, that might expedite natural biodegradation, such as in-situ biological
treatment; oxygen or hydrogen release compounds; or chemical oxidation.
(Related to comments 27 and 28 above and responses to those should satisfy
this comment)
Other Comments on Data Quality
37.QC data wa~ not included in data package. The laboratory needs to provide LCS,
MS, MSD information to further evaluate the data provided.
(While we didn't include the 6-inches of laboratory-provided QA data, we did
provide our Data Quality Assessment Summary which is an independent review
of both the field and lab QA. John Blanchard was going to get with his QA
person to review our summary for applicability and decide if it is sufficient.)
38.The laboratory should provide a Case Narrative Summary report stating that the
QC department has reviewed all results). Include the Case Narrative Summary
in this work plan.
(The lab's Case Narrative Summary was not included per se, but was reviewed
during our Data Quality Assessment. It can be included in the revised work plan
and in subsequent monitoring reports.)
9
UC,IV u c,/.(.12 ·I'•-' vv I I
• Kubal-Furr & Associates.
------------Environmental Management Service,------------
Post Office Box 273210
Tampa, FL 33688-3210
[phone]
FAX [phone]
[e-mail]
Ms. Giezelle S:Bennett
U.S. Environmental Protection
Agency, Region IV
61 Forsyth Street
Atlanta, GA 30303
Dear Ms. Bennett:
July 11, 2001
Post Office Box 80247
Simpsonville, SC 29680-0247
[phone]
FAX [phone]
[e-mail]
During the June 21, 2001 Ticona-Shelby site visit for the Five-Year Review, you requested
that Ticona prepare a brief letter summarizing the justification for its recommendation to
discontinue pumping from the Inner Tier recovery wells. On behalf of Ticona, I have prepared
this letter in response to your request.
The following items have been considered in Ticona's recommendation that EPA revisit the
remedy selected in the record of decision and that it allow Ticona to implement a monitored
natural attenuation demonstration project:
• The Inner Tier extraction well system is intended specifically to recover residual ground-
water contamination from around the former OU-2 source area. Although OU-2 was not
clean-closed, remediation consisted of excavation to a depth 1-ft below the obviously
contaminated soil, followed by incineration, stabilization and reburial of the treated
sludges and other waste materials. While some residual soil and ground-water
contamination remain, there is no continuing source of release to the ground water from
the former OU-2 area and it has subsequently been delisted from the NPL.
• As the Inner Tier extracts ground water, it creates a cone of depression around each well
which extends toward the former source area. This produces an unsaturated zone above
the water table which still contains residual soil contamination. When the pumps are shut
off, the area becomes saturated, residual contamination is released to the ground-water
system and concentrations of constituents at monitor wells rebound to levels that may
exceed remedial goals. A monitored natural attenuation approach proposed by Ticona
would address this residual source material and may be a preferable remedy in
combination with periodic or cyclic pumping to remove contaminated ground water.
• While the Inner Tier pumping remains protective, it is not particularly efficient. The
Inner Tier has shown a steady decline in its ability to recover residual ground-water
contamination despite repeated attempts by Ticona to maintain and upgrade system
performance including redeveloping and rehabilitating all wells; installing larger
diameter, higher capacity replacement wells; and, replacing the problematic bladder
• • Ms. Giezelle Bennett -

2

-
July 11, 2001
•
pumps with different types of submersible pumps. Maintenance difficulties associated
with the Inner Tier have been reported in the routine semiannual reports, while the
declining performance of the Inner Tier in general has been described in detail in the
draft Five-Year Review Report (Kubal-Furr & Associates; December 1999).
The principal risk posed by the residual ground-water contamination at the former source
area is currently to the on-site worker having to maintain the system trying to keep it
operational. Routine replacement of bladder pumps, clearing of air lines, reworking of
screens, etc. expose the workers to contamination brought to the surface during
maintenance activities which they would not normally be exposed to. This worker
exposure increases coincidentally with the continued decline in performance of the Inner
Tier system.
• The decline in Inner Tier production is due to a combination of physical, chemical and
biological factors. Physically, the upper water bearing formation in which the Inner Tier
wells are installed is composed of saprolite, a residual clayey material resulting from the
weathering of the native bedrock. Although this formation contains water, it is not
considered an aquifer in the classical sense because it's incapable of producing water at
appreciable rates. Chemically, iron and manganese cause the submersible pumps to
freeze up. Biologically, the principal contaminant, ethylene glycol, is readily degradable
and has caused biofouling and bacterial build-up outside the well casings and along the
well screens. This combination of factors has produced a pump and treat remedy which is
inefficient.
While pump and treat was a presumptive remedy in the 1980 's at virtually every Superfund
site with ground-water contamination, it has been demonstrated in a majority of cases to be less
than effective in remediating aquifer systems. This was the basis for EPA's Directive 9200.0-22
entitled "Superfund Reforms: Updating Remedy Decisions." This directive encourages the
Regions to: " ... take a close look at, and modify as appropriate, past remedy decisions where
those decisions are substantially out of date with the current state of knowledge in remediation
science and technology, and thus are not as effective from a technical or cost perspective as they
could be."
Specifically, one of the principal types of remedy updates anticipated in this directive were:
"Modification of the remediation objectives due to physical limitations posed by site conditions
or the nature of the contamination." We feel the Ticona site is exactly the type of site that the
directive on updating remedy decisions was intended to revisit, and we respectively request that
you consider the site in this context as you conduct your Five-Year Review.
As we discussed in detail during your site visit, Ticona feels a monitored natural attenuation
(MNA) approach to remediating the residual contamination around the former source area will
be as effective as the current pump and treat remedy. Ticona is requesting that EPA and DENR
agree to the following plan of action:
1) Ticona will collect a baseline set of MNA ground-water data, under pumping conditions,
from the following locations: Inner Tier wells, around the former OU-2 source area and
in selected background locations.
Kubal-Furr & Associates
• •
Ms. Giezelle Bennett -

3

-
July 11, 2001
2) Ticona will be permitted to shut down the Inner Tier wells, allow the system to
equilibrate and, for a period of from 18-24 months, begin collecting routine data to
evaluate the effectiveness of MNA as a remedy. Because the ground-water flow rate in
the saprolite is very low (less than a few feet per year), shutting down the wells will have
a negligible effect on contaminant migration during the evaluation phase.
3) Ticona will submit routine status reports to the EPA and DENR presenting the MNA
data. At the end of the demonstration period, Ticona will prepare a final summary report
evaluating the MNA remedy. Implementation of this project would provide Ticona ample
time to generate sufficient data to support a formal ROD amendment or modification
which both the EPA and DENR could support.
Ticona is preparing a draft site-wide sampling plan for Shelby which includes, as an element,
the proposed MNA baseline sampling program. This plan will be finalized by August 10, 2001,
and Ticona would like to get EPA and DENR's concurrence to implement the above-described
plan of action by September 3, 2001.
I'd be glad to answer any questions you may have following your review of this information.
Please give me a call at 813-265-2338.
Sincerely,
Kubal-Furr & Associates
.J' I/ 6 . ,, ' ~ , • I ' (~ .. / er-'· ·--.. t.. {_~•
I
Jerry ,E. Kubal, P.O.
President
cc: Mr. McKenzie Mallary, USEPA
Mr. Grover Nicholson, NCDENR
Mr. Steve Olp, Celanese Acetate
Mr. Jerry McMurray, Ticona-Shelby ESHA
Mr. Everett Glover, P .E., Earth Tech
Kubal-Furr & Associates