&EPA
United States
Environmental Protection
Agency
1200 Pennsylvania Avenue, N.W.
Washington, DC 20460
Office of Solid Waste and Emergency Response
April 2009
Support Document for the
Revised National Priorities List
Final Rule-
Attebury Grain Storage Facility
(Guam
Trust Territories
American Samoa
Northern Mariana Islands
VI
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Support Document for the
Revised National Priorities List
Final Rule
Attebury Grain Storage Facility
April 2009
Site Assessment and Remedy Decisions Branch
Office of Superfund Remediation and Technology Innovation
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
Washington, DC 20460
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Attebury Grain Storage Facility NPL Listing Support Document
Table of Contents
Table of Contents ii
Executive Summary iii
Introduction iv
Background of the NPL iv
Development of the NPL v
Hazard Ranking System v
Other Mechanisms for Listing vi
Organization of this Document vii
Glossary vii
Response to Comments iii
1. List of Commenters/Correspondents iii
2. Site Description 1
3. Summary of Comments/Correspondence 2
3.1 Support for Listing 2
3.2 Origin of Release/Liability 2
3.3 Association of Substances with Source 3
3.4 Likelihood of Release-Significant Increase 7
3.5 Likelihood of Release-Attribution 9
3.5.1 EDB and Site Inspection 9
3.5.2 Representativeness of EDB Contaminated Wells 10
3.5.3 Other Sources 13
3.6 Waste Characteristics/Toxicity 17
4. Conclusion 19
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Attebury Grain Storage Facility NPL Listing Support Document
EXECUTIVE SUMMARY
Section 105(a)(8)(B) of CERCLA, as amended by SARA, requires that the EPA prepare a list of national
priorities among the known releases or threatened releases of hazardous substances, pollutants, or
contaminants throughout the United States. An original National Priorities List (NPL) was promulgated
on September 8, 1983 (48 FR 40658). CERCLA requires that EPA update the list at least annually.
This document provides responses to public comments received on the Attebury Grain Storage Facility
site, proposed on September 3, 2008 (73 FR 51393). This site is being added to the NPL based on an
evaluation under EPA's Hazard Ranking System (HRS) in a final rule published in the Federal Register
in April 2009. Several additional sites are being promulgated concurrently.
in
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Attebury Grain Storage Facility NPL Listing Support Document
INTRODUCTION
This document explains the rationale for adding the Attebury Grain Storage Facility site in Happy, Texas,
to the National Priorities List (NPL) of uncontrolled hazardous waste sites and also provides the
responses to public comments received on this site. The EPA proposed this site on September 3, 2008
(73 FR 51393). This site is being added to the NPL based on an evaluation under the Hazard Ranking
System (HRS) in a final rule published in the Federal Register in April 2009.
Background of the NPL
In 1980, Congress enacted the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA), 42 U.S.C. Sections 9601 et seq. in response to the dangers of uncontrolled hazardous waste
sites. CERCLA was amended on October 17, 1986, by the Superfund Amendments and Reauthorization
Act (SARA), Public Law No. 99-499, stat, 1613 et seq. To implement CERCLA, EPA promulgated the
revised National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR Part 300, on
July 16, 1982 (47 FR 31180), pursuant to CERCLA Section 105 and Executive Order 12316 (46 FR
42237, August 20, 1981). The NCP, further revised by EPA on September 16, 1985 (50 FR 37624) and
November 20, 1985 (50 FR 47912), sets forth guidelines and procedures needed to respond under
CERCLA to releases and threatened releases of hazardous substances, pollutants, or contaminants. On
March 8, 1990 (55 FR 8666), EPA further revised the NCP in response to SARA.
Section 105(a)(8)(A) of CERCLA, as amended by SARA, requires that the NCP include
criteria for determining priorities among releases or threatened releases throughout the
United States for the purpose of taking remedial action and, to the extent practicable, take
into account the potential urgency of such action, for the purpose of taking removal
action.
Removal action involves cleanup or other actions that are taken in response to emergency conditions or
on a short-term or temporary basis (CERCLA Section 101 [23]). Remedial action is generally long-term
in nature and involves response actions that are consistent with a permanent remedy for a release
(CERCLA Section 101 [24]). Criteria for placing sites on the NPL, which makes them eligible for
remedial actions financed by the Trust Fund established under CERCLA, were included in the HRS.
EPA promulgated the HRS as Appendix A of the NCP (47 FR 31219, July 16, 1982). On December 14,
1990 (56 FR 51532), EPA promulgated revisions to the HRS in response to SARA, and established the
effective date for the HRS revisions as March 15, 1991.
Section 105(a)(8)(B) of CERCLA, as amended, requires that the statutory criteria provided by the HRS be
used to prepare a list of national priorities among the known releases or threatened releases of hazardous
substances, pollutants, or contaminants throughout the United States. The list, which is Appendix B of
the NCP, is the NPL.
An original NPL of 406 sites was promulgated on September 8, 1983 (48 FR 40658). At that time, an
HRS score of 28.5 was established as the cutoff for listing because it yielded an initial NPL of at least 400
sites, as suggested by CERCLA. The NPL has been expanded several times since then, most recently on
September 3, 2008 (73 FR 51368). The Agency also has published a number of proposed rulemakings to
add sites to the NPL. The most recent proposal was on September 3, 2008 (73 FR 51393).
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Attebury Grain Storage Facility NPL Listing Support Document
Development of the NPL
The primary purpose of the NPL is stated in the legislative history of CERCLA (Report of the Committee
on Environment and Public Works, Senate Report No. 96-848, 96th Cong., 2d Sess. 60 [1980]).
The priority list serves primarily informational purposes, identifying for the States and
the public those facilities and sites or other releases which appear to warrant remedial
actions. Inclusion of a facility or site on the list does not in itself reflect a judgment of the
activities of its owner or operator, it does not require those persons to undertake any
action, nor does it assign liability to any person. Subsequent government actions will be
necessary in order to do so, and these actions will be attended by all appropriate
procedural safeguards.
The NPL, therefore, is primarily an informational and management tool. The identification of a site for
the NPL is intended primarily to guide EPA in determining which sites warrant further investigation to
assess the nature and extent of the human health and environmental risks associated with the site and to
determine what CERCLA-financed remedial action(s), if any, may be appropriate. The NPL also serves
to notify the public of sites EPA believes warrant further investigation. Finally, listing a site may, to the
extent potentially responsible parties are identifiable at the time of listing, serve as notice to such parties
that the Agency may initiate CERCLA-financed remedial action.
CERCLA Section 105(a)(8)(B) directs EPA to list priority sites among the known releases or threatened
release of hazardous substances, pollutants, or contaminants, and Section 105(a)(8)(A) directs EPA to
consider certain enumerated and other appropriate factors in doing so. Thus, as a matter of policy, EPA
has the discretion not to use CERCLA to respond to certain types of releases. Where other authorities
exist, placing sites on the NPL for possible remedial action under CERCLA may not be appropriate.
Therefore, EPA has chosen not to place certain types of sites on the NPL even though CERCLA does not
exclude such action. If, however, the Agency later determines that sites not listed as a matter of policy
are not being properly responded to, the Agency may consider placing them on the NPL.
Hazard Ranking System
The HRS is the principle mechanism EPA uses to place uncontrolled waste sites on the NPL. It is a
numerically based screening system that uses information from initial, limited investigations ~ the
preliminary assessment and site inspection ~ to assess the relative potential of sites to pose a threat to
human health or the environment. HRS scores, however, do not determine the sequence in which EPA
funds remedial response actions, because the information collected to develop HRS scores is not
sufficient in itself to determine either the extent of contamination or the appropriate response for a
particular site. Moreover, the sites with the highest scores do not necessarily come to the Agency's
attention first, so that addressing sites strictly on the basis of ranking would in some cases require
stopping work at sites where it was already underway. Thus, EPA relies on further, more detailed studies
in the remedial investigation/feasibility study that typically follows listing.
The HRS uses a structured value analysis approach to scoring sites. This approach assigns numerical
values to factors that relate to or indicate risk, based on conditions at the site. The factors are grouped
into three categories. Each category has a maximum value. The categories are:
• likelihood that a site has released or has the potential to release hazardous substances into the
environment;
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Attebury Grain Storage Facility NPL Listing Support Document
• characteristics of the waste (toxicity and waste quantity); and
• people or sensitive environments (targets) affected by the release.
Under the HRS, four pathways can be scored for one or more threats as identified below:
• Ground Water Migration (Sgw)
- drinking water
• Surface Water Migration (Ssw)
The following threats are evaluated for two separate migration components, overland/flood
migration and ground water to surface water.
- drinking water
- human food chain
- sensitive environments
• Soil Exposure (Ss)
- resident population
- nearby population
- sensitive environments
• Air Migration (Sa)
- population
- sensitive environments
After scores are calculated for one or more pathways according to prescribed guidelines, they are
combined using the following root-mean-square equation to determine the overall site score (S), which
ranges from 0 to 100:
4
If all pathway scores are low, the HRS score is low. However, the HRS score can be relatively high even
if only one pathway score is high. This is an important requirement for HRS scoring because some
extremely dangerous sites pose threats through only one pathway. For example, buried leaking drums of
hazardous substances can contaminate drinking water wells, but ~ if the drums are buried deep enough
and the substances not very volatile ~ not surface water or air.
Other Mechanisms for Listing
There are two mechanisms other than the HRS by which sites can be placed on the NPL. The first of
these mechanisms, authorized by the NCP at 40 CFR 300.425(c)(2), allows each State and Territory to
designate one site as its highest priority regardless of score. The last mechanism, authorized by the NCP
at 40 CFR 300.425(c)(3), allows listing a site if it meets the following three requirements:
• Agency for Toxic Substances and Disease Registry (ATSDR) of the U.S. Public Health Service
has issued a health advisory that recommends dissociation of individuals from the release;
• EPA determines the site poses a significant threat to public health; and
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• EPA anticipates it will be more cost-effective to use its remedial authority than to use its
emergency removal authority to respond to the site.
Organization of this Document
The following section contains EPA responses to site-specific public comments received on the proposal
of the Attebury Grain Storage facility site on September 3, 2008 (73 FR 51393). The site discussion
begins with a list of commenters, followed by a site description, a summary of comments, and Agency
responses to each comment. A concluding statement indicates the effect of the comments on the HRS
score for the site.
Glossary
The following acronyms and abbreviations are used throughout the text:
1,2-DCA 1,2-dichloroethane
Agency U.S. Environmental Protection Agency
ATSDR Agency for Toxic Substances and Disease Registry
bgs below ground surface
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act of
1980, 42 U.S.C. Sections 9601 etseq., also known as Superfund
CTC carbon tetrachloride
EDB 1,2-dibromethane
EPA U.S. Environmental Protection Agency
HRS Hazard Ranking System, Appendix A of the NCP
HRS score Overall site score calculated using the Hazard Ranking System; ranges from 0 to
100
MCL Maximum Contaminant Limit
MDL Method Detection Limit
NCP National Oil and Hazardous Substances Pollution Contingency Plan, 40 C.F.R.
Part 300
NPL National Priorities List, Appendix B of the NCP
Rl Remedial Investigation
SARA Superfund Amendments and Reauthorization Act of 1986, Public Law No. 99-
499, stat, 1613 etseq.
SQL Sample quantitation limit
SSI Screening site inspection
TCEQ Texas Commission of Environmental Quality
T/M Toxicity/mobility
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1. List of Commenters/Correspondents
EPA HQ-SFUND-2008-0083-0004 Letter from Rick Perry, Governor of Texas to Richard E.
Greene, Regional Administrator, EPA Region 6, dated
December 14, 2008.
EPA-HQ-SFUND-2008-0083-0005 Comment submitted by Gerald J. Pels, Counsel,
Sutherland, Asbill & Brennan LLP on behalf of Attebury
Grain, LLC, dated May 19, 2008.
EPA-HQ-SFUND-2008-0083-0006 Comment submitted by Michael W. Steinberg, Counsel,
Morgan, Lewis & Bockius LLP on behalf of Superfund
Settlement Projects (SSP), dated June 2, 2008.
2. Site Description
The Attebury Grain Storage Facility site is located in the panhandle of Texas approximately 30 miles
south of Amarillo, Texas, and west of Interstate 27 in downtown Happy, Texas. The site consists of a
release of 1, 2-dibromethane (EDB), carbon tetrachloride (CTC), and 1,2-dichloroethane (1,2-DCA) to
ground water. The source of the release was attributed to the use of a CTC-based mixture containing
EDB and 1,2-DCA to extinguish a fire when the grain storage facility (elevator and bins) on property that
is now owned by Attebury Grain, Inc. burned down in 1962. The ground water contamination extends off
the grain storage property to several public and private wells that serve the City of Happy and its
residents.
The principal source of drinking water in the City of Happy is the Ogallala Aquifer, which is found at a
depth of 150 feet below ground surface (bgs). The regional ground water flow gradient in this aquifer is
to the east-southeast, but because of heavy use of the aquifer for irrigation and municipal purposes and the
limited aquifer recharge due to the hot, dry climate in which evaporation rates exceed the rainfall rate, this
aquifer is being drawn down and local flow gradient is likely to be affected by the pumping of nearby
wells.
An observed release of EDB, CTC, and 1,2-DCA to the Ogallala Aquifer was documented by chemical
analysis of ground water samples. The presence of these three substances together was shown to be
logical given the history of their combined use. Prior to the 1970s, CTC was widely used as a grain
fumigant, frequently mixed with EDB and 1,2-DCA. Numerous mixtures containing CTC, EDB, and 1,2-
DCA used in the post harvest storage industry were manufactured under a variety of trade names. Prior to
1970s, CTC was used as a fire extinguishant because of its fire retarding properties.
One City of Happy municipal well was closed in 1991 because the concentration of CTC exceeded EPA's
Safe Drinking Water Act Maximum Contaminant Level (MCL). In follow-up, in August 2006 the Texas
Commission of Environmental Quality (TCEQ) sampled several city and private wells in Happy in the
vicinity of the location of the 1962 fire. Hazardous substances found included CTC, 1,2-DCA, and EDB.
EDB was found in one of the wells (GW-09A) together with CTC and 1,2-DCA. When released into the
soil, these contaminants will either evaporate into the air or travel down through the soil and enter the
ground water.
TCEQ conducted sampling in March and November 2007 during its screening site inspection (SSI),
collecting ground water samples. EDB was detected in samples from two wells (GW-09A and GW-22;
see Figure 3 of the HRS documentation record as proposed)
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Attebury Grain Storage Facility NPL Listing Support Document
In addition to sampling the ground water, a soil vapor well was installed on the Attebury site and soil
vapor samples were collected during the August 2006 sampling event. EDB was detected in a soil vapor
sample at a depth of 95-100 feet. Soil vapor sampling in the source area also indicated the presence of
CTC under the source location at depths from 7 to 100 feet, with the highest concentrations of CTC found
between 95 to 100 feet, the depth at which EDB was also found.
EPA and TCEQ performed a search for other possible sources of the three contaminants, including
investigating the use of fumigants at the other two grain storage facilities in Happy, and identifying other
possible sources of these substances based on other uses, but could not document any releases of the
contaminants from other sources.
3. Summary of Comments/Correspondence
Rick Perry, Governor of Texas, submitted a comment supporting the listing of this site. In a December
14, 2007, letter to the EPA Region 6 Administrator, Governor Perry expressed his support of listing the
Attebury Grain Storage Facility site on the NPL based on EPA and TCEQ evaluations of the site under
the federal HRS.
Michael W. Steinberg, Counsel, Morgan, Lewis & Bockius LLP, on behalf of Superfund Settlements
Project, submitted a general comment that applied to all EPA NPL listing proposals included in the March
19, 2008, proposed rule (73 FR 14742). This comment focused on the need for EPA to present its
rationale (i.e., reasons for listing) and purpose of listing for each site to encourage dialogue between the
Agency and stakeholders. EPA responds to this comment in the preamble to the rule promulgating this
site to the NPL.
Gerald J. Pels, Counsel, Sutherland, Asbill & Brennan LLP, on behalf of Attebury Grain, LLC,
commented that the addition of the Attebury Grain Storage Facility site to the NPL is inappropriate and
requested that EPA reconsider its proposed listing. Mr. Pels asserted that EPA did not adequately
document EDB association with the site source or attribution of an EDB release to the site, that EPA did
not sufficiently demonstrate there were no other sources of the EDB ground water contamination, that
EPA did not adequately establish a significant increase of EDB above background levels, and that EPA
had improperly used the toxicity and mobility of EDB to reflect the risk posed by the site.
3.1 Support for Listing
Comment: The Governor of Texas expressed his support of listing the Attebury Grain Storage Facility
site on the NPL based on EPA and TCEQ evaluations of the site under the federal HRS.
Response: EPA is adding the Attebury Grain Storage Facility site to the NPL. Listing makes a site
eligible for remedial action funding under CERCLA. EPA will examine the site to determine the
appropriate response action(s), which will include identifying the sources of the ground water
contamination. EPA will determine the need for using Superfund monies for remedial activities on a site-
by-site basis, taking into account the NPL ranking, State priorities, further site investigation, other
response alternatives, and other factors as appropriate. Actual funding of site remediation may not
necessarily be undertaken in the precise order of HRS scores and, upon more detailed investigation, may
not be necessary at all in some cases.
3.2 Origin of Release/Liability
Comment: In his summary of the facts used by EPA to determine an HRS score for the Attebury Grain
Storage Facility site, Mr. Pels stated that Attebury Grain, Inc. (the present owner of the grain storage
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facility) was not associated with the release of EDB, CTC, or 1,2-DCA, which forms the basis for the
HRS score. For example, he stated:
• Attebury avers that it never used CTC (or, EDB, or 1, 2-DCA for that matter) at the site
during the period of its ownership (1986-Present).
• EPA attributes CTC concentrations to use (alleged to be by the former site owner) of the
chemical or a mixture containing it, to extinguish a grain elevator fire in 1962, contending
that any excess liquid containing CTC, along with any other fire fighting fluids, would have
a significant chance to enter the soil and migrate to the ground water.
Response: EPA does not consider whether any party may be liable for response costs when evaluating a
site under the HRS. The NPL serves primarily as an informational and management tool. The
identification of a site for the NPL is intended primarily to guide EPA in determining which sites warrant
further investigation to assess the nature and extent of the human health and environmental risks
associated with the site and to determine what CERCLA-fmanced remedial action(s), if any, may be
appropriate. Identification of a site for the NPL does not reflect a judgment on the activities of the
owner(s) or operator(s) of a site. It does not require those persons to undertake any action, nor does it
assign any liability to any person. Subsequent government actions will be necessary in order to do so,
and these actions will be attended by all appropriate procedural safeguards. This position, stated in the
legislative history of CERCLA, has been explained in the Federal Register (48 FR 40759, September 8,
1983 and 53 FR 23988, June 24, 1988).
3.3 Association of Substances with Source
3.3.1 Comment: Mr. Pels stated that EPA did not offer any reasonable explanation or any facts
supported by the HRS documentation record to link EDB to the site. In questioning the linkage
of EDB with the site, Mr. Pels raised questions regarding the association of EDB with the site
source, which consists of releases of EDB, CTC, and 1,2-DCA that allegedly were used to
quench a grain elevator fire in 1962. Mr. Pels concluded there is no evidence in the
administrative record establishing that a release of EDB occurred at the Attebury site.
Response: EDB was appropriately associated with the site source, as documented in the HRS
documentation record as proposed, and is properly included in the HRS evaluation.
Inclusion of a contaminant in the HRS evaluation does not require that the hazardous substance
be documented in the source specifically by sampling, or that specific source(s) of the
hazardous substances be documented at all, provided that definitive information does not
indicate the contrary. The HRS identifies the requirements for association of hazardous
substances with a source in HRS Section 2.2.2, Identify hazardous substances associated with a
source. It states that:
[fjor each of the three migration pathways; [the user] consider those hazardous
substances documented in a source (for example, by sampling, labels, manifests,
oral or written statements) to be associated with that source when evaluating each
pathway. In some instances, a hazardous substance can be documented as being
present at a site (for example, by labels, manifests, oral or written statements),
but the specific source(s) containing that hazardous substance cannot be
documented. For the three migration pathways, in those instances when the
specific source(s) cannot be documented for a hazardous substance, consider the
hazardous substance to be present in each source at the site, except sources for
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which definitive information indicates that the hazardous substance was not or
could not be present.
As discussed on pages 14-16 of the HRS documentation record as proposed, the only known
source of an EDB release (and CTC and 1,2-DCA releases) in the vicinity of Happy was the use
of a fumigant to quench a fire that occurred in December 1962. When an explosion and fire
occurred at the grain storage facility on property now owned by Attebury Grain, Inc., the owner
of the facility applied three drums of a fumigant containing CTC or a CTC mixture, likely
containing EDB and 1,2-DCA, onto the smoldering grain in an attempt to extinguish the fire, a
fact not disputed by the commenter.
EPA associated EDB with the site source for three primary reasons: (1) EDB was shown to
likely be present in the fumigant mix that was used to quench the 1962 fire at the site; (2) EDB
was documented in a soil vapor sample taken from below the location of the fire; and (3) EPA
could identify no other source of EDB in the vicinity of the site.
EPA considers it more likely than not that EDB was in the fumigant mix used to quench the
fire. Prior to the 1970s, CTC was commonly mixed with other substances, such as EDB or 1,2-
DCA, in fumigants. Reference 18 of the HRS documentation record as proposed lists
numerous fumigant mixtures containing CTC, EDB, and 1,2-DCA sold for use in the United
States under a variety of trade names with uses in the post harvest industry. Given how often
commercial fumigant mixtures that contained CTC also contained EDB and 1,2-DCA, it is
likely that the CTC material that the facility owner had on the property and used on the fire was
a mixture of CTC, EDB, and 1,2-DCA. Combined with the information regarding use of CTC-
containing drums to quench the fire, by an eyewitness statement (see Reference 53 of the HRS
documentation record as proposed) it is sufficient to link EDB with the source.
That EDB was found in a soil vapor sample collected beneath the location of the fire was
pointed out by Mr. Pels in his comments and is documented on page 16 of the HRS
documentation record as proposed. While Mr. Pels commented on the adequacy of this
information, as explained in section 3.3.3 of this support document, his comments did not alter
the finding of EDB in the sample or its use in associating EDB with the site source. The soil
vapor sampling documented on page 16 of the HRS documentation record as proposed links
EDB to the source.
The documentation of the finding of no other source of the EDB release and responses to Mr.
Pels comments on the adequacy of EPA's effort to find other sources is discussed in detail in
section 3.5.3 of this support document. As discussed in that section, EPA's search was
sufficient and consistent with the HRS requirements. Moreover, Mr. Pels only speculated about
the possibility of other sources of EDB and did not provide any documentation to support his
speculation.
Together, the three considerations presented above are sufficient to associate EDB with the site
source.
Furthermore, the HRS contains specific instructions on how to score a site where a substance is
present at the site, such as in an observed release, but the information necessary to associate the
substance with a source is considered incomplete. HRS Section 2.2.2, Identify hazardous
substances associated with a source, states that:
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In some instances, a hazardous substance can be documented as being present at
a site (for example, by labels, manifests, oral or written statements), but the
specific source(s) containing that hazardous substance cannot be documented.
For the three migration pathways, in those instances when the specific source(s)
cannot be documented for a hazardous substance, consider the hazardous
substance to be present in each source at the site, except sources for which
definitive information indicates that the hazardous substance was not or could not
be present.
Therefore, even if the specific source of EDB could not be documented, because EDB has been
documented as being at the site through establishing it as an observed release substance, EDB
can still appropriately be considered associated with the site source in the HRS evaluation.
Moreover, the information discussed above regarding the likelihood of EDB having been
present in the released CTC pesticide mixture negates the inference that definitive information
exists to show that the substance could not be present.
3.3.2 Comment: Mr. Pels commented that the Agency accepts the unsupported assumption that other
potential industrial sources in the area have not used CTC (or its mixtures) at face value, and
that neither the administrative record nor the reference documents support this assumption. Mr.
Pels concluded that EDB may have come from a different source.
Response: As discussed in section 3.5, Likelihood of Release -Attribution, of this support
document, and specifically in section 3.5.3, Other Sources, of this support document, EPA
conducted sufficient efforts to document, in accordance with the HRS, that there are no other
known sources of EDB releases in the vicinity of this site.
As discussed in more detail below, EPA's search for possible sources of EDB and the other
release substances focused mainly on other possible grain elevators in the area that also may
have used fumigants. EPA considered that the documentation that CTC, EDB, and 1,2-DCA
were commonly found as co-ingredients in pesticide formulations associated with the grain
storage industry, coupled with the finding that EDB was found in ground water and soil vapor
only in the presence of CTC, supported the conclusion that the source of the EDB and the CTC
is likely the same common source, possibly a result of fumigant applications in the grain
storage business.
Therefore, as discussed on page 30 of the HRS documentation record as proposed, EPA
identified three grain storage elevator facilities in the City of Happy, including the Attebury
Grain Storage Facility. The fact that three drums of CTC or CTC mixture were available and
used to put out the 1962 fire reasonably establishes that CTC-containing fumigants were used
at the Attebury Grain Storage Facility. EPA and TCEQ obtained documentation that the two
other grain storage facilities in the City of Happy claimed they never used CTC during the time
period they were operators of the facilities (see References 11 and 12 of the HRS documentation
record as proposed). The statements in the HRS documentation record regarding CTC use at
grain elevator facilities (see References 11 and 12 of the HRS documentation record as
proposed) were submitted in response to a formal TCEQ request for information. Since this
information was requested under state authority, there is a firm basis to believe the information
is accurate. The Agency routinely uses information collected by States in its HRS evaluations.
The documentation of TCEQ's request for this information is in the site investigation report
(see Reference 8 of the HRS documentation record as proposed).
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As further support, EPA has since sent out CERCLA section 104(e) information request letters
to the same grain elevator companies from which TCEQ requested information and received
similar responses to those already in the HRS documentation record (see References 11 and 12
of the HRS documentation record as proposed). These 104(e) letters are being added to the
administrative record for the final rule listing the Attebury Grain Storage Facility site on the
NPL. These references serve as confirmation of the evidence in the HRS documentation record
at proposal (see References 11 and 12 of the HRS documentation record as proposed).
Because the grain elevator companies' denials do not cover the entire period that those grain
elevator storage facilities have been present, EPA considered the possibility that use of CTC or
CTC mixtures containing EDB as fumigants might have caused the ground water
contamination during periods not covered by the denials. EPA concluded that the City of
Happy's climate and the considerable depth to ground water at the City of Happy is not
conducive to downward migration of volatile substances such as CTC and EDB to ground
water depths when used as fumigants under normal climate conditions in the area.
In addition, fumigant mixtures are designed and applied at the lowest possible rates to protect
against infestation. Therefore, EPA concluded "in the Panhandle of Texas [it is more likely
that] fumigants applied to grains would [more] likely be lost to volatilization rather than
migrating to ground water."
EPA and TCEQ also looked for other sources of 1,2-DCA and identified that it had been used
as a gasoline additive, but found no evidence of a release from storage facilities in the City of
Happy.
Therefore, EPA was able to document only one release of EDB that was likely to be
sufficiently significant to lead to the contamination in the Ogallala Aquifer. As presented in the
HRS documentation record as proposed, the only CTC and EDB source EPA could document
was the 1962 fire at the grain storage facility on the property now owned by Attebury Grain,
Inc. EPA reasoned that any excess liquid containing a CTC mixture along with other fire
fighting liquids, such as the large quantities of water that had been applied, would have a
significant chance to enter the soil and migrate to ground water. This is further supported by
the finding of CTC in soil vapor at several depths and EDB at the deepest sampled depth under
the site of the fire 45 years later. In addition, a former City of Happy Volunteer fire department
chief indicated that he knew of no other fires at grain elevators or leaking of CTC that occurred
from the 1960s to 1998.
That the only source of EDB documented to be part of the site is the release associated with the
1962 fire, coupled with the finding of EDB in soil vapor under the fire location and EDB being
a common ingredient in grain storage fumigants, especially those also containing CTC (see
section 3.3.1 of this support document), is sufficient rationale for associating EDB with the site
source.
3.3.3 Comment: In stating that the linkage of EDB to the site based on its presence in a single soil
vapor sample is "dubious," Mr. Pels raised questions regarding the association of EDB with the
only site source. He questioned the linkage to the source by stating that EDB was not detected
in soil vapor samples from 7 to 10 foot depth and from 47 to 52 foot depth at the Attebury site,
but rather was detected closer to ground water table at 95 to 100 foot depth. Mr. Pels
concluded that if EDB were used at the site even in 1962, it would likely be closer to the
surface.
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Attebury Grain Storage Facility NPL Listing Support Document
Response: Although Mr. Pels is correct that EDB was not identified above detection limits in
soil vapor samples at depths less than 100 feet, its association with the site source is
nonetheless consistent with the HRS. As explained in section 3.3.1 of this support document,
association of a substance with a source can be by sampling or non-sampling methods. EPA
used both methods in this site.
As documented on page 16 of the HRS documentation record as proposed and on pages!3-15
of Reference 17 of the HRS documentation record as proposed, EDB was detected (0.480 ppbv)
in a soil vapor sample from 95 to 100 foot depth. EPA agrees that EDB was not found in soil
vapor samples from shallower depths (2 to 7 feet and 47 to 52 feet) at the same location. EPA
notes that CTC was found at shallower depths, although the highest concentration was in the 95
to 100 foot depth.
One reason EDB was found 45 years after the fire in a sample from a greater depth and not at
shallower depths and is still present due to the fire-related release is that the EDB
contamination has likely volatilized out of the soil at the shallower depths. The situation at the
site is conducive to volatilization. The climate at the City of Happy is hot, dry, and semi-arid
with 16 to 18 inches of rain a year, the temperature ranges from the mid 90s in the summer to
the 40s in the winter (see page 15 of Reference 31 of the HRS documentation record as
proposed), and the evaporation rate is around 70 inches a year, more than three times the
rainfall rate (see page 17 of Reference 31). Given the 45 years since the fire, it is entirely
reasonable under these conditions that the EDB has volatilized out of the soil at the shallower
depths.
The reason that CTC was found at shallower depths but EDB was not could be that not all the
CTC had volatilized at the shallower depths because its initial concentration in the fumigant
mixture was considerably higher than that of EDB. As shown in Reference 18 of the HRS
documentation record as proposed, in most fumigants containing both CTC and EDB, the
amount of EDB is a fraction of the amount of CTC in the mixture. Given that the detection
limits for EDB and CTC are approximately the same (as documented in the various tables
showing the EDB and CTC concentrations and quantitation limits for both substances on pages
25-29 of the HRS documentation record as proposed), it is reasonable to conclude that in the
shallower soil depths where volatilization of substances from the soil more readily occurs, the
concentration of EDB may have dropped below the quantitation limits whereas the
concentration of the remaining CTC has not, and why this same situation has not occurred at
greater depths. This supports both the presence of EDB at the 95 to 100 foot depth and the
presence of CTC at shallower depths.
Hence, sampling information does not show that linkage of EDB to the 1962 fire source is
dubious, nor does it document that another source of EDB exists.
3.4 Likelihood of Release-Significant Increase
Comment: Mr. Pels commented that EPA appears to have incorrectly reported the results for EDB in
GW-09A (0.535 (ig/L) and GW-22 (0.044 (ig/L) from the November 2007 sampling event as observed
releases, when the SQL for the non-detected background samples (i.e., March 2007 samples from wells
GW-04 and GW-21) appears to be 1.0 (ig/L. Mr. Pels stated that this is significant in that the HRS
documentation record specifies that "[i]f the background concentration is not detected (or is less than the
detection limit), an observed release is established when the sample measurement equals or exceeds its
own sample quantitation limit [(SQL)] and that of the background sample." (emphasis in original). Mr.
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Pels argued that even the detection level set for EDB at the background wells could skew the HRS results
in this case.
Response: Mr. Pels' comment is correct that the background samples listed on page 25 have an EDB
SQL above that of the concentration of EDB in the two release samples collected in November 2007. Mr.
Pels, however, is incorrect in judging the impact of these data on the identification of EDB as an observed
release substance. As presented in HRS Table 2.3, an observed release can be established when the
sample measurement is greater than or equal to the SQL:
If the background concentration is not detected (or is less than the detection limit), an
observed release is established when the sample measurement equals or exceeds the
sample quantitation limit.
As explained on page 25 of the HRS documentation record as proposed, EPA did not use the two
background samples to set a background level, but rather to show that EDB was not ubiquitous. EPA
explained:
Because some man-made substances [including EDB] are not found ubiquitously in the
environment, they can be attributed only to a contaminant source. (Ref 25, p.2) [Ref 25 is an
EPA fact sheet titled Establishing Background Levels}. The presence of these substances in the
release is sufficient to show contamination; a background sample is not needed (Ref. 25, p.2).
CTC, EDB, and 1,2-DCA are man-made hazardous substances that are not naturally occurring
and sampling data from background wells have demonstrated these substances are not
ubiquitous in the vicinity of the site.
March 2007 samples from wells GW-04 and GW-21 were selected as representative background samples
because they both had no detectable concentrations of EDB, CTC or 1,2-DCA and therefore support that
these substances are not ubiquitous in the vicinity of the site.
EPA agrees that because the SQL is 1 |ig/L in March 2007 samples from wells GW-04 and GW-21, these
samples only document that EDB, CTC, and 1,2-DCA are not ubiquitous at or above the 1 (ig/L
concentration. Therefore, EPA has revised the HRS documentation record to replace these samples with
appropriate samples from other sampling events in the HRS documentation record as proposed that
clearly show that EDB, CTC, and 1,2-DCA are not ubiquitous in the vicinity of the site at concentrations
comparable to the detection limit of the observed release samples presented for this purpose as proposed.
As identified in Table 6 on pages 27-29 of the HRS documentation record as proposed, EPA collected
samples from numerous wells in the City of Happy as part of three separate sampling events (i.e., August
2006, March 2007, and November 2007). The samples from the different sampling events were analyzed
for EDB using similar methods with different reported quantitation limits. Analytical data results for
these three events are documented in References 16, 39, and 13 of the HRS documentation record as
proposed, respectively.
Because of the differences in the reported detection limits and the difference in the times of the sampling
events, separate background samples have been identified for the 2006 and the November 2007 sampling
events in which EDB was found in release wells. In addition the locations of some of these background
samples are upgradient of the site source based on the regional flow gradient of east-southeast. (See
Figure 3 of the HRS documentation record as proposed.)
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The table below presents both the analytical results for the EDB release samples concentrations as
presented in the HRS documentation record as proposed and the newly selected background samples that
appear in the HRS documentation record at promulgation. EPA notes that the data for the background
samples included in the HRS documentation record at promulgation were in the record at the time of
proposal although not used for the purpose of demonstrating that substances are not ubiquitous (i.e., no
new data were added to the record).
Sample Location
(Date Sampled)
GW-09A (Aug. 2006)
GW-09A (Nov 2007)
GW-22 (Nov 2007)
EDB Sample
Concentration
(SQL)
0.32J ng/L (0.04 ng/L)
0.535 jig/L (0.019 jig/L)
0.044 jig/L (0.019 ng/L)
Background Sample Location(s)
(Date Sampled)
(EDB Concentration)
GW-01 and GW-04 (Aug 2006) (0.04U
Hg/L)
(Ref 4, p. 10; Ref 16, pp. 110-116)
GW-04, GW-1 1 and GW-13 (Nov 2007)
(0.019U jig/L)
(Ref. 13, pp. 73-76, 85)
Notes: U Not detected at the reported detection limit
J Analyte detected below quantitation limit
For the August 2006 sampling event, two samples from wells GW-01 and GW-04 were selected to
indicate that EDB was not ubiquitous at that time; both samples have non-detected results for EDB at an
SQL of 0.04 (ig/L. Both these well locations are located upgradient of the location of the 1962 fire based
on regional flow gradient (page 24 of the HRS documentation record as proposed).
For the November 2007 sampling event, the samples selected to document that EDB was not ubiquitous
at that time are from wells GW-04, GW-11, and GW-13. As noted above, well GW-04 is located
upgradient from the site source based on the regional flow gradient. Wells GW-11 and GW-13 are
downgradient of the site source, but nonetheless support the conclusion that EDB is not ubiquitous in the
vicinity of the site.
The new background samples document that EDB is not ubiquitous in the vicinity of the site at
concentrations above 0.04 (ig/L, and 0.019 (ig/L for August 2006 and November 2007 samples,
respectively. These levels are significantly below the 2006 release sample EDB concentration of 0.32J
(ig/L and the November 2007 EDB release sample concentrations 0.535 (ig/L and 0.044 (ig/L.
Therefore, all three EDB release samples were appropriately used to establish observed releases of EDB
using data in the HRS documentation record as proposed.
3.5
Likelihood of Release-Attribution
Mr. Pels commented that EPA cannot justify its attribution of EDB to the Attebury Grain Storage Facility
and submitted the following specific comments. These comments and EPA's responses are presented in
sections 3.5.1 through 3.5.3 of this support document.
3.5.1 EDB and Site Inspection
3.5.1.1 Comment: Mr. Pels stated that EPA did not include EDB in its screening analysis. He
commented that the SSI Report did not take into account EDB because it was not reported, that
the SSI Report also does not provide any evidence that releases in the wells (at the levels
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identified in GW-09A and GW-22) are attributable to the site, and that this is because there is
no evidence in the administrative record establishing that a release of EDB occurred at the
Attebury site. Mr. Pels concluded that EPA's own documents provide that the SSI must serve
as the basis for listing. Thus EPA must rely upon findings in the SSI when computing a HRS
[score] for a facility, and that EPA has failed this requirement.
Response: Mr. Pels is incorrect that EDB was not included in EPA's screening analysis or
taken into account in the SSI Report. Whereas Mr. Pels is correct that EPA relied on findings
in the SSI when computing an HRS score for the facility, he is incorrect that the SSI is the only
source EPA can rely on for this purpose.
Regarding inclusion of EDB in EPA's screening analysis and the SSI Report, the Site
Characterization section of the SSI Report (see Reference 8 of the HRS documentation record
as proposed) and pages 14-16 of the HRS documentation record as proposed, describe the
history of investigation at the site and discuss contaminants found at the site including EDB,
CTC, and 1,2-DCA. EDB was associated with the site in August 2006 prior to initiation of the
SSI in 2007. Ground water samples collected as part of the SSI in March 2007 were analyzed
for EDB, although EDB was not detected in these samples. In the November 2007 sampling
during the SSI, EPA collected additional ground water samples from wells at the site and
analyzed them for EDB. EDB was detected in these samples above the detection limit, and
these sample results were used in the scoring of the site.
Regarding reliance on the SSI, the HRS (40 CFR Part 300, Appendix A) does not require that
EPA use any particular source of information when evaluating a site under its terms. Thus,
whereas EPA may rely on the findings of the SII in HRS scoring, it may also consider other
data.
3.5.2 Representativeness of EDB Contaminated Wells
Mr. Pels commented that the EDB contaminated wells were not representative of site
conditions or any release alleged to have occurred there, and that EPA does not offer any
reasonable explanation or any facts supported by the record to link EDB to the site and which
account for the alleged presence of EDB in the upgradient wells. His specific comments on this
topic and EPA's responses are provided in sections 3.5.2.1 through 3.5.2.3.
3.5.2.1 Comment: Mr. Pels stated that EPA has not established that local ground water flow is
contrary to the regional flow direction. Mr. Pels continued that EPA attempted to explain the
high EDB in upgradient wells by rationalizing that because there are no other documented
sources of EDB upgradient, and that pumpage of city and private wells must have influenced
local ground water flow and therefore contaminant transport and distribution. Mr. Pels stated
that "[t]he Agency, however, neither substantiates its claim that there are no other sources nor
the conclusion that it draws from it regarding the effect of well pumpage on local groundwater
flow." Mr. Pels specifically commented that, "[tjhese wells [GW-09A and GW-22] are located
north-northeast and east-northeast, respectively, from the Site. Significantly, these locations
are away from the east-southeasterly gradient of the Ogallala Aquifer and underlying strata in
the region surrounding the Site, and therefore upgradient from the general direction of the
plume allegedly emanating from the Site." In addition, Mr. Pels pointed out that "Well 22
would appear to be cross-gradient of the Site, but down-gradient of Well 9A."
Response: EPA agrees that it did not demonstrate that the local ground water flow gradient was
different than the regional flow gradient. The HRS does not require EPA to do so. In
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establishing an observed release by chemical analysis to ground water, EPA did not rely on
ground water flow gradients to attribute the release of the EDB to the site or to establish
background concentration levels to establish a significant increase in contaminant
concentrations.
The basic HRS requirements to establish an observed release by chemical analysis are
contained in HRS Section 2.3, Likelihood of release. This section states:
The minimum standard to establish an observed release by chemical analysis is
analytical evidence of a hazardous substance in the media significantly above the
background level. Further, some portion of the release must be attributable to the
site.
The specific HRS requirements for establishing an observed release by chemical analysis to
ground water are in HRS Section 3.1.1, Observed release. This section states that an observed
release by chemical analysis is established when
an analysis of ground water samples from the aquifer indicates that the
concentration of hazardous substance(s) has increased significantly above the
background concentration for the site (see section 2.3). Some portion of the
significant increase must be attributable to the site to establish the observed
release [.]
Thus, the HRS does not require that the background levels be established based on flow
direction or specify how the attribution must be established. EPA agrees that upgradient
samples are certainly an appropriate way to establish background and that flow gradient should
be considered in establishing attribution, but in some cases, such as at this site, the information
necessary to do so is not available.
Because EPA and TCEQ did not have local flow gradient information, they first reviewed the
information already available. As noted by Mr. Pels, EPA identified that based on regional
flow direction the highest contamination levels were in wells that would be considered slightly
upgradient (about 1,200 feet) of the fire location. Thus, the highest concentration location
appears to contradict the regional flow direction assumption.
However, as stated on page 24 of the HRS documentation record as proposed, EPA found no
documented releases of CTC, EDB or 1,2-DCA between the location of the well with the
highest contaminant concentrations (GW-09A) and the location of the fire source (see Figure 3
of the HRS documentation record as proposed). Therefore, EPA looked for other reasons for
this seeming contradiction in contaminant concentration and flow direction.
The first possible reason is that the contamination was not necessarily traveling only vertically
as it migrated to the ground water. The depth to ground water (the Ogallala Aquifer) in the
vicinity of this site is well over 100 feet, and well GW-09A was screened from 150 to 200 feet
(see page 26 of the HRS documentation record as proposed). As detailed on page 23 of the
HRS documentation record as proposed, the stratum between the land surface and the Ogallala
Aquifer is called the Quaternary System, and is composed of highly permeable sand with nearly
impermeable caliche. (Caliche is mainly a calcium carbonate deposit that cements the sand
together.) Water movement through the quaternary caliche deposit is through cracks and
fissures or through well boreholes. The presence and depth of the caliche/sand layer at this site
is represented in the geologic cross section on page 14 of Reference 8 in the HRS
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documentation record as proposed. Thus, it is logical that the contamination releases during the
fire could have migrated both horizontally and vertically to the northeast before reaching the
ground water in the Ogallala Aquifer.
The second possible explanation for what appears to be contaminant transport counter to the
regional flow direction is that, as identified by the commenter, the local flow direction is not
the same as the regional flow direction. As is documented in several of the geologic references
(see References 29, 30, and 31 of the HRS documentation record as proposed), the entire
Ogallala Aquifer in general, and in Swisher County and under the City of Happy specifically, is
being drawn down at the estimated rate of between 0.50 to 3.53 feet per year for wells with
saturated sections between 10 to 110 feet due to the limited recharge of the aquifer and the
heavy use of the ground water for irrigation. This amount of drawdown would certainly locally
override or at least alter a regional flow gradient at least during periods when irrigation and
public supply wells are being pumped. In fact, given that large amounts of water may have
been used during the suppression of the fire in which the CTC mixture was released, it is
logical that the drawdown caused by the pumpage of the fire water could have significantly
distorted the local flow gradient at the time of the fire.
Therefore, EPA considered that although the CTC, EDB, and 1,2-DCA contamination
concentrations appear to be higher at a location that would be contrary to the regional flow
gradient, given that no other release of these substances could be identified, that the caliche
layer might have caused horizontal migration as the contamination moved to the ground water,
and that the drawdown of public and irrigation wells in the area could distort regional flow
direction locally, it was reasonable for EPA to attribute the ground water contamination to the
1962 fire incident.
3.5.2.2 Comment: Mr. Pels questioned the suitability of samples from well GW-21 to represent
upgradient conditions for EDB and to indicate that the contamination in samples from well
GW-9A could be attributed to the fire-related source. Mr. Pels stated:
In fact, GW 9A - which has a higher EDB reading than GW 22 - is located upgradient
from GW-21, one of the two wells chosen to provide background levels for the region.
Presumably GW 21 was chosen because its location was unaffected by the plume. It is,
therefore, incongruous to associate high EDB readings found in GW 9A with
contamination from the Site. GW-09A is so close to GW-21 that it could arguably
represent background conditions.
Response: While Mr. Pels has misunderstood EPA's rationale for selecting well GW-21 as a
background sample location, for a different reason EPA revised the set of background samples
used in the HRS documentation record to establish that EDB is not ubiquitous and the
background level of non- detect for EDB (see section 3.4 of this support document). However,
these changes have no effect on the attribution of EDB in samples from well GW-09A to the
site.
As explained in section 3.4 of this support document, EPA selected a sample from well GW-21
as a background sample not because of its location relative to the source or the releases wells,
but because the sample from it documented that EDB was not ubiquitous at or above the SQL
for that sampling event. Well GW-21's relative location in terms of flow gradient was not a
factor in its selection. The sample from well GW-21, however, has been replaced not because
of the well's location but because the sample's SQL was higher than the EDB release
concentrations, as Mr. Pels pointed out.
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As described in section 3.4 of this support document, five different samples from four well
locations are presented in the HRS documentation record at promulgation to establish a
background level of non-detect for EDB. Samples from these wells, GW 01, GW 04, GW-11
and GW-13 (see Figure 3 of the HRS documentation record as proposed), were selected to
reflect background conditions both because EDB was not found above the SQL in samples
from them, and because they are located in different directions from the site. Thus, the samples
from these wells support the conclusion that EDB was not ubiquitous in the vicinity of the site.
Regarding the adequacy of the evidence supporting the attribution of the EDB in well GW-09A
to the site, as explained in section 3.3.1 of this support document, the rationale presented in the
HRS documentation record is sufficient to attribute the EDB in well GW-09A to the site. Mr.
Pels presented no actual information, only speculation, to the contrary.
3.5.3 Other Sources
Mr. Pels questioned EPA's conclusion that there were no other sources of EDB contributing to
ground water contamination.
3.5.3.1 Comment: Mr. Pels stated that the "administrative record does not support the conclusion that
no other facilities in the area contributed to EDB concentrations near the Site."
Response: EPA provided sufficient rationale to attribute the release of EDB to the site source.
HRS Section 3.1.1, Observed release, requires that:
[s]ome portion of the significant increase must be attributable to the site to
establish the observed release, except when the source itself consists of a ground
water plume with no identified source, no separate attribution is required.
The HRS documentation record lists EDB, as well as CTC and 1,2-DCA, as observed release
substances whose significant increase is in part due to releases from the site (see page 31 of the
HRS documentation record as proposed). The support for the attribution of all three substances
to the site is on pages 30-31 of the HRS documentation record as proposed. Further
information on the uses of EDB is presented on page 16 of the HRS documentation record as
proposed as part of the description of the site source (the release associated with the use of CTC
or a CTC mixture to put out the 1962 fire).
As discussed in the Attribution section on pages 30-31 of the HRS documentation record as
proposed, in support of EPA's conclusion that no other facilities in the area are known to have
contributed to the release of EDB, EPA and TCEQ (1) identified common uses of the release
substances, (2) identified that numerous mixtures of EDB, CTC, and 1,2-DCA have been
commonly used in the post harvest grain storage industry, and (3) searched for possible sources
of these substances in the vicinity of the site at other possible industrial and commercial
facilities in Happy.
As discussed in the Source Identification section on page 16 of the HRS documentation record
as proposed, EPA and TCEQ documented that CTC, EDB, and 1,2-DCA have been commonly
used as grain fumigants, and that CTC has been used as a fire extinguishant. In support of
these statements, EPA provided References 7, 26, and 52. Reference 7 is a report by the
Congressional Research Service of the Library of Congress titled Ethylene Dibromide: History,
Health Effects, and Policy Questions. Reference 26 is an Agency for Toxic Substances and
Disease Registry (ATSDR) report titled ToxFAQs for EDB. Reference 52 is monograph from a
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joint expert panel meeting including Food and Agriculture Organization of the United Nations
(FAO) and World Health Organization (WHO) experts on pesticide residues in food and the
environment.
EPA also documented the use of EDB in mixtures with CTC in fumigants. EPA provided
References 52 and 18 of the HRS documentation record as proposed in support. Reference 52
discusses the possible health impacts of the residual of such fumigants on crops. Reference 18
is an excerpt from the Scorecard Chemical Profiles database, a publicly available internet
database (available online at http://www. scorecard.org/chemical-profiles/) listing six pages of
commercial fumigants that are mixtures containing both CTC and EDB.
EPA's search for possible sources of EDB and the other release substances focused mainly on
other possible grain elevators in the area that also may have used fumigants. EPA considered
that the documentation that CTC, EDB, and 1,2-DCA were commonly found as co-ingredients
in pesticide formulations associated with the grain storage industry, coupled with the finding
that EDB was found in ground water and soil vapor only in the presence of CTC (see pages 16
and 27 of the HRS documentation record as proposed), supported the conclusion that the source
of the EDB and the CTC is likely the same common source, possibly a result of fumigant
applications in the grain storage business.
Therefore, as discussed on page 30 of the HRS documentation record as proposed, EPA
identified three grain storage elevator facilities in the City of Happy, including the Attebury
Grain Storage Facility. The fact that three drums of CTC or CTC mixture were available and
used to put out the 1962 fire (see Reference 53 of the HRS documentation record as proposed)
reasonably establishes that CTC-containing fumigants were used at this facility. EPA and
TCEQ obtained documentation that in 1991 the two other grain storage companies in the City
of Happy claimed they never used CTC during the time period they were operators of the
facilities (see Reference 11 and 12 of the HRS documentation record as proposed).
Because the other elevator companies' denials do not cover the entire period that those grain
elevator storage facilities have been present, EPA considered the possibility that use of CTC or
CTC mixtures containing EDB as fumigants might have caused the ground water
contamination during periods not covered by the denials. EPA concluded that the City of
Happy's climate and the considerable depth to ground water at the City of Happy is not
conducive to downward migration of volatile substances such as CTC and EDB to ground
water depths when used as fumigants under normal climate conditions. These conditions are a
hot, dry semiarid climate with 16 to 20 inches of rain a year and temperature ranges from the
mid-90s in the summer to the 40s in the winter (see page 15 of Reference 31 of the HRS
documentation record as proposed); an annual evaporation rate of around 70 inches of rain a
year, more than 3 times the rainfall rate (see page 17 of Reference 31 of the HRS documentation
record as proposed); and depth to ground water of more than 100 feet (see well logs for wells in
Reference 27 of the HRS documentation record as proposed).
In addition, as also documented on page 30 of the HRS documentation record as proposed,
fumigant mixtures are designed and applied at the lowest possible rates to protect against
infestation, and only small quantities are applied when used as a fumigant, generally 4 gallons
per 1,000 bushels of produce (see page 58 of Reference 54 of the HRS documentation record as
proposed). Therefore, EPA concluded "in the Panhandle of Texas [it is more likely that]
fumigants applied to grains would [more] likely be lost to volatilization rather than migrating to
ground water."
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EPA and TCEQ also looked for other sources of 1,2-DCA and identified that it had been used
as a gasoline additive, but found no evidence of a release from storage facilities in the City of
Happy (see page 30 of the HRS documentation record as proposed.)
Therefore, EPA was able to document only one release of EDB that was likely to be
sufficiently significant to lead to the contamination in the Ogallala Aquifer. As also presented
on pages 30-31 of the HRS documentation record as proposed, the only CTC and EDB source
EPA could document was the 1962 fire at the grain storage facility on the property now owned
by Attebury Grain, Inc., in which multiple drums of CTC fumigant, most probably mixed with
EDB and 1,2-DCA, were placed on the smoldering grain after water had been applied. EPA
reasoned that any excess liquid containing a CTC mixture along with other fire fighting liquids,
such as the large quantities of water that had been applied, would have a significant chance to
enter the soil and migrate to ground water. This is further supported by the finding of CTC in
soil vapor at several depths and EDB at the deepest sampled depth under the site of the fire 45
years later. In addition, a former City of Happy Volunteer fire department chief indicated that
he knew of no other fires at grain elevators or leaking of CTC that occurred from the 1960s to
1998 (see Reference 53 of the HRS documentation record as proposed).
Based on the above information, EPA concluded that the application of a CTC mixture to
extinguish the 1962 fire on the property now owned by Attebury Grain, Inc. was the most likely
source of the EDB contamination in the ground water at this site.
Mr. Pels made several comments speculating about the possibility of other sources of EDB, but
did not actually identify any.
3.5.3.2 Comment: In reference to EPA's assertion that there was no other facility or source in the
vicinity contributing to the EDB contamination, Mr. Pels commented that:
In fact, the record actually provides evidence that there potentially are additional
contaminant sources. For example, the TCEQ observes in its May 2007 SSI Report,
that in addition to CTC and other volatile organics, metals such as copper and lead had
been detected above background levels in the wells affected by the plume. Because
there is no identification in the record that these metals would necessarily be attributed
to the Site, one could reasonably conclude that their presence indicates that other
industrial sources contributed to pollution in the region.
Response: As explained in section 3.5.3.1 of this support document, EPA and TCEQ
performed a search for other sources of EDB in the vicinity of the site and were unable to
document any other source. Regarding the possibility of EDB coming from a source of copper
and lead, EPA agrees that copper and/or lead were found at elevated levels in a few well
samples (GW-11, GW-13, and GW-30) (see pages 23-25 of Reference 8 of the HRS
documentation record as proposed). However, EPA has no reason, nor did Mr. Pels provide
any documentation, to associate EDB with a lead or copper source. Further, examination of the
EDB and CTC levels in samples in relation to the levels of these metals in the samples clearly
indicates that elevated CTC and EDB levels are not found in the same well samples as the
metals, suggesting that the CTC-EDB contamination and the copper-lead contamination are not
from the same source.
3.5.3.3 Comment: In support of his challenge to the attribution of and observed release of EDB to the
site, Mr. Pels stated that EPA:
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accepts the following unsupported assumptions at face value: (1) that other potential
industrial sources in the area have not used CTC (or its mixtures) and (2) EDB could
have been used in mixtures with CTC and therefore "probably" was present in the CTC
allegedly used to douse the 1962 fire at the Site. Neither the administrative record nor
the Reference documents support these assumptions.
Response: EPA supported its attribution of an observed release of EDB to the site in the HRS
documentation record as proposed in accordance with HRS requirements (see pages 30-31 of
the HRS documentation record as proposed). As discussed in sections 3.3.2 and 3.5.3.1 of this
support document, EPA has explained why it attributed a release of EDB to the site and cited
documentation that supports that rationale, in the HRS documentation record as proposed on
pages 16, 31, and 32. This discussion specifically included EPA's activities regarding its
search for and consideration of other sources of EDB that could have contributed to the EDB
release and documentation for why it considered EDB associated with the 1962 fire source.
Mr. Pels has presented no documentation or rationale, only speculation, for why EPA's
rationale is inadequate or incorrect.
3.5.3.4 Comment: Mr. Pels questioned the adequacy of EPA's search for other sources of the release
of EDB, stating:
Historic releases from a variety of sources have unquestionably occurred in the area.
There is no other basis to explain the presence of 1,2 DCA, a chlorinated solvent,
having no connection with the grain storage business. EPA acknowledges this, and in
that case attributes it to other industrial sources including its general use as a solvent or
historic usage as a gasoline additive."
Response: EPA considered the possibility that 1,2-DCA could have been released from other
sources in the City of Happy, and that EDB could also have been associated with these other
sources, and found no evidence to support this conclusion.
Mr. Pels is incorrect in his statement that 1,2-DCA has no connection with the grain storage
business. EPA presented, on pages 30-31 of the HRS documentation record as proposed, its
explanation for associating 1,2-DCA with the grain storage business in attributing a release of
1,2-DCA as part of the fumigant mixture released while extinguishing a fire in 1962. EPA
further identified that this fire was extinguished in 1962 at the grain storage facility on the
property now owned by Attebury Grain, Inc., using CTC or a CTC mixture. EPA identified
that 1,2-DCA was in numerous fumigant mixtures used in the post harvest storage industry at
the time of the fire, noting that these mixtures also contained CTC or EDB (see the Source
Identification section on page 16 of the HRS documentation record as proposed and the
discussion on documentation of the use of 1,2-DCA, EDB, and CTC in fumigant mixes in
section 3.5.3.1 of this support document). Thus, 1,2-DCA can be associated with the grain
storage business in general and the Attebury Grain, Inc., property specifically.
EPA also considered the possibility that 1,2-DCA might have been released from other sources
in the area. As Mr. Pels acknowledged, EPA identified on page 30 of the HRS documentation
record as proposed, that 1,2-DCA has been used as a fuel additive as well as multiple other
uses. Based on this information, EPA considered the possibility that the release of 1,2-DCA
came from other sources, and in doing so, identified 12 gas stations in the City of Happy and
examined the records for any evidence of fuel spills (also documented on page 30 of the HRS
documentation record as proposed). Specifically, EPA examined a TCEQ database of leaking
petroleum storage tanks and found no evidence of leakage from tanks in the city (see Reference
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14 of the HRS documentation record as proposed). Thus, since EPA could find no evidence of
another source of a release of 1,2-DCA, it also had no basis for associating EBD with another
source.
Furthermore, Mr. Pels presented no documentation of other sources releasing 1,2-DCA in the
vicinity of the City of Happy, or a rationale for why EDB would be associated with other
sources of 1,2-DCA if they did exist.
3.6 Waste Characteristics/Toxicity
3.6.1 Comment: Mr. Pels protested the use of EDB toxicity in the scoring of the site. He stated that
EPA incorrectly used the EDB toxicity value in its HRS analysis, and that EPA cannot attribute
EDB to the site as "there are no facts supporting a nexus of EDB to any release to the Attebury
Site" for reasons discussed in section 3.5 of this support document and later in this section of
this support document. Mr. Pels stated that for these reasons, CTC is the most reliable
constituent upon which to base the HRS score. On the basis of the foregoing, Mr. Pels claimed
that "EPA erred and was arbitrary and capricious in selecting the toxicity/mobility ("T/M")
factor for EDB (10,000) in evaluating the waste characteristics of the groundwater pathway for
this Site." He stated, "[t]he only appropriate selection in this instance is the T/M factor for
CTC (1,000) given its more widespread prevalence in the wells down-gradient from the Site."
This would produce a "revised Waste Characteristics Factor Value of 18, which consequently
results in a reduced HRS score of 18.1908 for the Site, excluding it from NPL consideration."
Response: The use of the EDB toxicity and mobility in determining the HRS score of the site
is consistent with the HRS regulation, whereas the use of the toxicity and mobility of CTC in
determining the HRS score of the site, as suggested by the commenter, would be in
contradiction to the HRS regulation. HRS Section 3.2, Waste characteristics, identified which
substances are to be used in this determination. It requires that EPA
[e]valuate only those hazardous substances available to migrate from the sources
at the site to ground water. Such hazardous substances include:
• Hazardous substances that meet the criteria for an observed release to
groundwater.
• All hazardous substances associated with a source that has a ground
water containment factor value greater than 0 (see sections 2.2.2, 2.2.3
and 3.1.2.1).
HRS Sections 3.2.1, Toxicity/mobility, 3.2.1.1, Toxicity, 3.2.1.2,Mobility, and 3.2.1.3,
Calculation of Toxicity/Mobility Factor Value direct the calculation of toxicity, mobility, and
the combined toxicity/mobility factor values to each of the eligible substances. HRS Section
3.2.1.3 directs the scorer to:
Use the hazardous substance with the highest toxicity/mobility factor value for
the aquifer being evaluated to assign the value to the toxicity/mobility factor for
that aquifer.
Although questioned by Mr. Pels, as discussed in sections 3.3, 3.4 and 3.5 of this support
document, EDB is both associated with the site source and is an observed release substance.
Two other substances, CTC and 1,2-DCA, are also associated with the source (see pages 16-17
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of the HRS documentation record as proposed) and are in one or more observed releases from
the site (see page 31 of the HRS documentation record as proposed). That the source has a
ground water containment factor value greater than 0 is documented on page 10 of the HRS
documentation record as proposed.
As is documented on page 32 of the HRS documentation record as proposed, EDB has a
toxicity/mobility factor value of 10,000; CTC has a toxicity/mobility factor value of 1,000; and
1,2-DCA has a toxicity/mobility factor value of 100. Therefore, EPA correctly chose the EDB
value as the highest factor toxicity/mobility factor value, and used it when scoring the site.
Since CTC has a lower toxicity/mobility value than EDB, to select it, as suggested by the
commenter, would have been contrary to the HRS regulation.
3.6.2 Comment: Mr. Pels stated that EDB's toxicity value was inexplicably used in the HRS
Documentation Record to score the Attebury site because EDB was not detected above the
reporting limits in the sampling performed during the SSI and therefore was not considered in
the SSI analysis.
Response: As explained in section 3.6.1 of this support document, EPA properly used EDB's
toxicity value in the scoring of this site. As explained in section 3.5.1 of this support document,
EPA is not restricted to information collected as part of a single site investigation when scoring
a site. As discussed in sections 3.3, 3.4, and 3.5 of this support document, EDB was found at
observed release levels in three ground water samples collected as part of either a 2006 or a
2007 sampling event and in a soil vapor sample taken from the location of the site source in a
2006 sampling event. Therefore, as discussed in Section 3.6.1 of this support document, the
HRS requires that EDB be used in assigning the toxicity/mobility factor value for the site.
3.6.3 Comment: Mr. Pels commented that the November 2007 Sampling Event Summary supports
that EDB cannot be used as the default toxicity standard because "GW-21 is not considered a
background well, converse to what is stated in the Documentation HRS."
Response: As previously discussed in sections 3.4 and 3.5 of this support document, EPA has
identified other background wells and EDB can be documented as an observed release
substance based on 2006 and November 2007 sampling events. In addition, EDB is associated
with the site source. Therefore, as discussed in section 3.6.1 of this support document, the HRS
requires EDB be used in assigning the toxicity/mobility factor value for the site.
3.6.4 Comment: Mr. Pels stated that the November 2007 Sampling Event Summary supports that
EDB cannot be used as the default toxicity standard because only two contaminants of concern
(COCs) are listed in the report above MCLs: EDB is not listed.
Response: As discussed in section 3.6.1 of this support document, the HRS regulation does not
require a substance to be above MCLs to qualify for use in establishing the toxicity/mobility
factor for the site. Therefore, EPA's use of EDB in assigning the toxicity/mobility factor value
for the site is consistent with the HRS.
3.6.5 Comment: Mr. Pels stated there was an inconsistency in using the EDB toxicity factor value in
scoring the site because EDB was not consistently reported in samples taken during the SSI.
Response: As discussed in section 3.6.1 of this support document, EPA correctly used EDB in
assigning the toxicity/mobility factor value for the site based on its association with a site
source and its presence in an observed release by chemical analysis to ground water. The HRS
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does not require a substance be in multiple samples for it to be considered associated with a
source or in an observed release. EDB was correctly associated with the source and established
as an observed release substance based on chemical analysis as discussed in section 3.3, and
sections 3.4 and 3.5, respectively, of this support document.
3.6.6 Comment: Mr. Pels stated there was an inconsistency in using the EDB toxicity factor value in
scoring the site because EDB may have come from a different source.
Response: As discussed in section 3.5 of this support document and documented in the HRS
documentation record on pages 30-31, the release of EDB is attributable to this site. While Mr.
Pels alleged there were other sources contributing to the significant increase in EDB levels, he
did not document any other possible sources. Therefore, as explained in section 3.6.1 of this
support document, EDB was correctly used in the assigning a toxicity/mobility value for the
site. Further, even if EDB were present in other sources, because the EDB contamination is
commingled with the CTC releases, the other sources would be considered part of this site.
3.6.7 Comment: Mr. Pels stated there was an inconsistency in using the EDB toxicity factor value in
scoring the site because EDB's detection and/or linkage to the Site is dubious. Mr. Pels stated
that "the EDB was not collected in soil vapor samples from 7-10 foot depth and from 47-52
foot depth at the Attebury Site, but rather was detected closer to groundwater table at 95-100
foot depth." He asserted that even "if EDB were used at the site in 1962, it would likely be
closer to the surface."
Response: As discussed in sections 3.3.1 and 3.3.3 of this support document, although EDB
was not identified above detection limits in soil vapor samples at depths less than 100 feet, it
still was appropriately associated with the site source. Therefore, as discussed in section 3.6.1
of this support document, EDB was appropriately used in assigning the toxicity/mobility factor
value for the site.
4. Conclusion
The original HRS score for this site was 32.33. Based on the above response to comments, the score
remains unchanged. The final scores for the Attebury Grain Storage Facility site are:
Ground Water: 64.67
Surface Water: Not Scored
Soil Exposure: Not Scored
Air Pathway: Not Scored
HRS Score: 32.33
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