EPA/AMD/R01-02/023
2002
EPA Superfund
Record of Decision Amendment:
O'CONNOR CO.
EPA ID: MED980731475
OU01
AUGUSTA, ME
09/26/2002
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F. O'CONNOR COMPANY SUPERFUND SITE
RECORD OF DECISION AMENDMENT
OPERABLE UNIT 2
September 2002
U.S. Environmental Protection Agency - Region I
New England
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DECLARATION FOR THE RECORD OF DECISION AMENDMENT
A. SITE NAME AND LOCATION
F. O'Connor Company Superfund Site
Augusta, Kennebec County, Maine
CERCLIS Identification Number: MED980731475
PRP Lead
Operable Unit Two, Management Of Migration
B. STATEMENT OF BASIS AND PURPOSE
This decision document presents an amendment to the selected remedial action for the F. O'Connor
Company Superfund Site in Augusta, Maine which was chosen in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended, 42 U.S.C. §§
9601 et. seq. and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) as
amended, 40 C.F.R. Part 300. The Director of the Office of Site Remediation and Restoration has been
delegated the authority to approve this Record of Decision Amendment (ROD Amendment)..
This decision was based on the Administrative Record, which has been developed in accordance with
Section 113 (k) of CERCLA, and which is available for review at the Lithgow Public Library in Augusta,
Maine and at the United States Environmental Protection Agency (EPA) Region 1 Office of Site
Remediation and Restoration (OSRR) Records Center in Boston, Massachusetts. The Administrative
Record Index (Appendix B of this ROD Amendment) identifies each of the items comprising the
Administrative Record upon which the selection of the remedial action is based.
The State of Maine has concurred with the selected remedy.
C. ASSESSMENT OF THE SITE
The response action selected in this ROD Amendment is necessary to protect the public health or welfare
or the environment from actual or threatened releases of hazardous substances into the environment.
D. DESCRIPTION OF THE SELECTED REMEDY
This ROD Amendment changes the remedy originally selected in the 1989 ROD for the management of
migration operable unit (OU-2). This ROD Amendment makes minor changes and clarifications to the
source control and Riggs Brook remedies (OU-1 and OU-3, respectively).
The major components of the selected remedy include:
! Institutional controls to prevent the use of contaminated groundwater;
! Waiver of federal and state drinking water standards for a limited portion of the Site on the
basis of technical impracticability;
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Active recovery of separate-phase oil from the overburden soil and bedrock through annual
implementation of a vacuum-enhanced recovery system and passive recovery between
these annual implementations;
Long-term monitoring of site groundwater on a regular basis to evaluate changes in site
conditions over time; and
A review of the Site every five years to ensure that the remedy remains protective of
human health and the environment.
E. STATUTORY DETERMINATIONS
The selected remedy for OU-2 is protective of human health and the environment, complies with Federal
and State requirements that are applicable or relevant and appropriate to the remedial action (unless
justified by a waiver), is cost-effective, and utilizes permanent solutions and alternative treatment (or
resource recovery) technologies to the maximum extent practicable.
The remedy also satisfies the statutory preference for treatment as a principal element as the active oil
recovery system provides reduction in toxicity, mobility, and volume of contaminants through the
extraction and treatment of separate-phase PCB-laden oil.
Because this remedy will result in hazardous substances remaining on-site above levels that allow for
unlimited use and unrestricted exposure (groundwater and/or land use restrictions are necessary), a
review will be conducted every five years after initiation of remedial action to ensure that the remedy
continues to provide adequate protection of human health and the environment.
F. SPECIAL FINDINGS
Issuance of this ROD embodies specific determinations made by the Regional Administrator or his
designee pursuant to CERCLA. EPA determined that it was technically impracticable to restore
groundwater beneath a limited area of the Site to drinking water quality within a reasonable time frame.
Therefore, EPA waived the attainment of chemical-specific ARARs for this area of the Site. These
chemical-specific ARARs are either being met now or are expected to be met shortly throughout the rest
of the Site, and therefore will provide sufficient basis for EPA to make a statutory finding of compliance
for the chemical-specific ARARs presented in this ROD Amendment for the rest of the Site.
G. ROD DATA CERTIFICATION CHECKLIST
The following information is included in the Decision Summary section of this Record of Decision.
Additional information can be found in the Administrative Record file for this Site.
1. Chemicals of concern (COCs) and their respective concentrations.
2. Cleanup levels established for COCs and the basis for the levels.
3. Current and reasonably anticipated future land assumptions and current and potential future
beneficial uses of groundwater used in the ROD Amendment.
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4. Potential land and groundwater use that will be available at the Site as a result of the selected
remedy.
5. Estimated capital, operation and maintenance (O&M), and total present worth costs; discount
rate; and the number of years over which the remedy cost estimates are projected.
6. Key factor(s) that led to selecting the remedy.
H. AUTHORIZING SIGNATURES
This ROD Amendment documents the selected remedy for the F. O'Connor Superfund Site, Operable
Unit 2. This remedy was selected by USEPA with concurrence of the Maine Department of
Environmental Protection (MEDEP).
U.S. Environmental Protection Agency
By:
ichard ^/davagneroy Acting Director
Officejw Site Remediation and Restoration
Region 1
D
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Table of Contents
I. SITE NAME, LOCATION, DESCRIPTION AND RATIONALE FOR
AMENDMENT
II. SITE HISTORY AND ENFORCEMENT ACTIVITY 3
III. COMMUNITY PARTICIPATION 5
IV. SCOPE AND ROLE OF OPERABLE UNIT 5
V. DESCRIPTION OF CHANGES TO THE 1989 REMEDY 6
DESCRIPTION OF THE 1989 REMEDY 6
CHANGES TO THE 1989 REMEDY 8
VI. SUMMARY OF SITE CHARACTERISTICS 9
VII. SUMMARY OF SITE RISKS 14
VIII TECHNICAL IMPRACTICABILITY DETERMINATION 15
IX. COMPARATIVE ANALYSIS OF THE ORIGINAL REMEDY AND
OU-2 ALTERNATIVES 29
X. THE SELECTED REMEDY , 36
XL STATUTORY DETERMINATIONS 39
XII. DOCUMENTATION OF NO SIGNIFICANT CHANGES 43
XIII. STATEROLE 43
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Figures
1. Site Location Map
2. Site Plan
3. TI Zone
4. Restrictive Covenant
5. Designated Area, 1994, 1997, and 2002
6. TWA II
7. Site Plan with Cross Sections
8. Geologic Cross Section A - A'
9. Geologic Cross Section B - B'
10. Geologic Cross Section C - C'
11. Upland Marsh Study Area
12. Vertical Residual Oil Distribution A - A'
13. Vertical Residual Oil Distribution B - B'
14. Vertical Residual Oil Distribution C - C'
15. Inferred Bedrock Surface Elevation
16. Inferred Groundwater Flow
17. Conceptual Hydrogeologic Model prior to SCRA
18. Conceptual Hydrogeologic Model After SCRA
Tables
1. Comparison between 1989 ROD and 2002 ROD Amendment
2. PCB Results - TWA II
3. Chemical-Specific ARARs for TI Waiver
4. Gallons of Oil Recovered From TWA II Area Wells
5. Summary of Groundwater Monitoring Results Modified Method 680
6. Chemical-specific ARARs
7. Location-specific ARARs
8. Action-specific ARARs
Appendices
Appendix A - Responsiveness Summary
Appendix B - Administrative Record Index
Appendix C - State Concurrence Letter
Appendix D - References Cited
in
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F. O'CONNOR COMPANY SUPERFUND SITE
RECORD OF DECISION AMENDMENT
OPERABLE UNIT 2
September 2002
I. SITE NAME, LOCATION, DESCRIPTION AND RATIONALE FOR
AMENDMENT
SITE NAME: The F. O'Connor Company Superfund Site.
SITE LOCATION: The F. O'Connor Superfund Site is located in Augusta, Maine (Figure 1).
The twenty-three acre O'Connor site is located on Eastern Avenue/Route 17 in a predominately
rural neighborhood. The twenty-three acre site is located within a twenty-eight acre property
owned by Central Maine Power (CMP). The site is bordered by woodlands and a small poultry
farm to the north, U.S. Route 17 to the south, private properties and residences to the west, and
the west branch of Riggs Brook and its associated wetlands to the east. Public water has been
provided to surrounding residents, and is available for future development.
SITE DESCRIPTION: The site was the former location of transformer salvaging processes,
which included stripping and recycling transformers, some of which contained PCB-
contaminated oil. The F. O'Connor Company operated from the early 1950s through the late
1970s. As a result of releases of poly chlorinated biphenyls (PCBs), lead, chlorinated
polyaromatic hydrocarbons (cPAHs) and volatile organic compounds (VOCs) at the site, the site
was placed on the National Priorities List (NPL) in 1983. Principal features on the property
prior to remedial actions included an Upland Marsh, two surface water impoundments (Upper
and Lower Lagoons), three former outdoor transformer work areas (TWAs), and Riggs Brook
(Figure 2). Upon completion of the source control remedial action for Operable Unit 1 (OU-1)
the lagoons were restored as wetlands and the area encompassing the three TWAs was covered
with clean fill, re-graded, and successfully vegetated.
In 1996, EPA separated the site into three operable units. As noted above, OU-1 addressed the
source control remedial action, OU-2 addresses management of migration, and OU-3 addresses
Riggs Brook sediment and biota.
RATIONALE FOR AMENDMENT: On September 27, 1989, EPA, with concurrence
from the Maine Department of Environmental Protection (Maine DEP) and in accordance with
the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), 42
USC §§ 9601 et seq., issued the Record of Decision (ROD) for the O'Connor site. The ROD
selected the remedial action for the site and established the target cleanup goals for soil,
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sediments, surface water, and groundwater. Specifically, the ROD required the remediation of
two site components:
The source areas that were the TWAs and surrounding soils, sediments, and surface
water in the two lagoons (later designated as OU-1); and
Site groundwater that was contaminated with PCBs, benzene, and 1,4-dichlorobenzene,
(later designated as OU-2) and the Riggs Brook sediment and biota (later designated as
OU-3).
These two components, described separately in the 1989 ROD, were called the source control
(SC) component and the management of migration (MOM), respectively.
Based on an implementability assessment conducted as part of the remedial design studies in the
early 1990s, EPA wrote an Explanation of Significant Difference (ESD) in June 1994 to revise
the source control component of the selected remedy.
Under the ROD, the remedial action objective for the groundwater (OU-2) was to reduce
potential future public health risks from ingestion of PCB, benzene, and 1,4-dichlorobenzene-
contaminated groundwater (ROD, page 17). This objective was to be achieved using a
groundwater extraction system and an above ground treatment system. In addition, institutional
controls were to be temporarily established to reduce the potential for exposure to contaminated
groundwater and were to remain in place until the groundwater remediation was completed
(ROD, page 45). The ROD further specified that one or more pump tests would be conducted as
part of remedial design so that an appropriate groundwater extraction system could be
constructed.
In 1992, pump tests were carried out as part of the remedial design. As a result of this effort,
separate phase oil was found in bedrock wells, a condition not previously seen at the site.
Consequently, MOM efforts focused on oil recovery rather than groundwater extraction and
treatment of dissolved contaminants. Three efforts at active oil recovery using vacuum-
enhanced pumping were carried out between 1996 and 2001. In April 2002, CMP submitted an
evaluation of the technical practicability of restoring the groundwater at the O'Connor site to
drinking water quality within a reasonable period of time. This evaluation concluded that
because of the geology and hydrology at the site, there were no technologies which could
accomplish this objective. EPA and Maine DEP agreed with the conclusion of this TI
evaluation.
This ROD Amendment addresses changes to the MOM component of the original 1989 ROD,
following the conclusion of the source control remedial action (SCRA) for OU-1 and the TI
evaluation. This ROD amendment includes a TI waiver for overburden and bedrock
groundwater in a small portion of the twenty-three acre site (Figure 3). This ROD Amendment
also addresses minor changes/clarifications to the original 1989 remedy for OU-1, source
control, as modified by the 1994 ESD and 1995 invocation of the contingency alternative, and
for OU-3, Riggs Brook.
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Institutional controls in the form of a Declaration of Restrictive Covenant (Restrictive Covenant)
have been implemented for the twenty-three acre site to provide additional risk reduction by
controlling exposure to site groundwater (Figure 4). The use of groundwater beneath the site is
prohibited without prior written approval by Maine DEP.
This ROD Amendment and the documents which form the basis for the Amendment are
available at the following information repositories:
EPA Records Center
1 Congress Street, Suite 1100
Boston, MA 02114-2023
(617)918-1459
Hours: 10 a.m.-noon
2 p.m.-5 p.m.
Lithgow Public Library
45 Winthrop Street
Augusta, Maine 04330-5542
(207)626-2415
Hours: Tues - Wed: noon to 8 p.m.
Thurs: 8 a.m. to noon
Fri: 10 a.m. to 6 p.m.
Sat: 10 a.m. to 3 p.m.
Maine DEP
Ray Building
Hospital Street Augusta, Maine 04333
(207)287-2651
Hours: (by appointment)
Mon-Thurs: 8:30 a.m to 12:30 p.m.
12:30 p.m. to 4:30 p.m.
Friday: 8:30 a.m. to 12:30 p.m.
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
Details of the earlier site history and enforcement activities are presented in the 1989 ROD. The
following is an update to the site history and enforcement activities which have occurred since
issuance of the ROD.
In September 1989, EPA issued a ROD for the O'Connor site. The barn structure was to be
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decontaminated, demolished, and then disposed of offsite at appropriate facilities, standing water
and sediments in the two lagoons were to be removed, soils contaminated with PCBs, PAHs, and
lead were to be excavated and treated using solvent extraction, contaminated groundwater was to
be pumped from the soils and bedrock, treated, and then discharged, and sediments and fish in
Riggs Brook were to be sampled for ten years.
Performance standards for soil and sediment were set at 1 ppm PCBs, 1 ppm cPAHs, and 248
ppm lead. Performance standards for groundwater were set at 0.5 ppb PCBs, 5 ppb benzene,
and 27 ppb 1,4-dichlorobenzene. Performance standards for the standing water in the lagoons
were set at 0.065 ppb PCBs, 1.94 ppb lead, and 87 ppb aluminum. Performance standards for
Riggs Brook sediment and biota were set at 1 ppm PCBs and 2 ppm PCBs, respectively.
In September 1991, a Consent Decree between EPA and CMP was approved by the U.S. District
Court of Maine. With this Consent Decree, CMP agreed to perform and fund the remedy
selected in the 1989 ROD. One of the components of the remedy was institutional controls on
site groundwater. It was EPA's intent that those institutional controls would remain in effect until
remediation of the groundwater was complete.
The Consent Decree allowed for an evaluation of the solvent extraction technology selected for
the soils. Following this evaluation, EPA and Maine DEP agreed that this technology for the
site soils would not be able to attain the clean-up goals. As a result, in June 1994 EPA issued an
Explanation of Significant Differences (ESD) which modified the soil remedy. Soils containing
more than ten parts per million (ppm) PCBs or PAHs or 248 ppm lead would be treated using
solvent extraction technology, and soils containing between one to ten ppm PCBs or PAHs
would be consolidated into one area onsite and then covered with clean fill brought in from
offsite. This designated area is shown on Figure 4. In October 1995, EPA invoked the
contingency remedy set forth in the 1994 ESD. This ESD also included a contingency that
allowed for the offsite disposal of soil and sediment with greater than ten ppm PCBs and cPAHs
without first requiring on-site solvent extraction treatment.
At the same time as the ESD, a Declaration of Restrictive Covenant was executed between CMP
and Maine DEP. This Restrictive Covenant is currently in place.
On April 25, 1996, EPA agreed to delay completion of the MOM design, and to separate the
Riggs Brook component from the MOM as a third operable unit (OU-3). This was done so that
the sampling and analysis for Riggs Brook, the remedial action required by the ROD, could
begin prior to the completion of the MOM design. The SC component of the selected remedy
was designated as OU-1 and the MOM component was designated as OU-2.
Phase I of the source control remedial action was completed in 1996. This included site
preparation, and the decontamination, demolition, and off-site disposal of the barn. Phase II
activities, including the off-site disposal of contaminated soil and sediment and the covering of
the designated area, were completed in 1997.
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III. COMMUNITY PARTICIPATION
This ROD amendment meets the criteria for community involvement specified in Sections
300.435(c)(2)(ii)(A) through(H) of the NCP.
In June 2002 EPA published a Proposed Plan to amend the 1989 ROD. The Proposed Plan for
OU-2 called for institutional controls to prevent exposure to contaminated groundwater, active
recovery of separate phase oil as long as practicable, designation of a small portion of the site as
a TI zone where state and federal groundwater standards would be waived, long-term
monitoring, and five-year reviews. The amended cleanup plan was recommended because EPA
believed it offered the best balance among the nine criteria required to be reviewed under the
NCP, including the protection of human health and the environment and the reduction of
contamination through treatment. EPA held a public information meeting on June 24, 2002 and
a formal public hearing on July 9, 2002. The public comment period ran from June 19 to July
19, 2002. All formal comments received on the June 2002 Proposed Plan are summarized and
responded to in the Responsiveness Summary, which is included as Appendix A of this ROD
Amendment. In addition, comments received during the public information meeting are
summarized in the Responsiveness Summary.
Pursuant to Section 300.825(c) of the NCP, EPA updated the Administrative Record in June
2002 to add the documents which EPA relied on to form the basis for the decision to modify the
response action for OU-2 at the O'Connor site. See Appendix B for the Administrative Index.
IV. SCOPE AND ROLE OF OPERABLE UNIT
The O'Connor site was divided into three operable units in 1996, seven years after the ROD was
signed. The three units are as noted above, source control OU-1, groundwater OU-2, and Riggs
Brook OU-3. Remedial action for OU-1 was completed in 1997 and EPA, with concurrence
from Maine DEP, signed off on this component with the approval of the September 1998 Source
Control Remedial Action report (Woodard & Curran, 1998). The limited action required for
Riggs Brook by the 1989 ROD continues to be carried out.
This ROD amendment pertains to OU-2, although as described below, aspects of OU-1 and OU-
3 were discussed during the development of the TI evaluation and it was mutually agreed by all
parties (EPA, Maine DEP, and CMP) to address these aspects at the time of this ROD
amendment.
For OU-1, the 1994 ESD established that a portion of the site would be used to consolidate soil
and sediment containing levels between one and ten ppm of PCBs and/or cPAHs. This
designated area would be covered with twelve inches of clean soil, and an operation and
maintenance plan would be developed to ensure the integrity of this component. As
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conceptually presented in the BSD, the designated area was three to four acres bounded on five
sides with rounded turning points. As the actual excavation for the source control remedial
action evolved, the boundary of the designated area became a 25-sided polygon. As agreed
among all parties, this created a difficult situation for anyone inspecting the site to know where
the boundary was.
EPA has determined that the following changes to the designated area shall be incorporated into
this ROD Amendment: The designated area will be surveyed, the boundaries simplified to the
12-sided shape shown in Figure 4, and permanent markers placed at the turning points.
Operation and maintenance for OU-1 shall include the following changes:
At five year intervals coincident with each Five Year Review, composite samples from
ten locations randomly selected from the SCRA grid nodes will be collected from four to
eight inches below the surface and analyzed for PCBs.
It is not necessary to resample for PAHs based on the extensive data collected during the
SCRA.
In all other aspects, operation and maintenance shall remain as specified in the 1994 BSD.
Regarding OU-3, the 1989 ROD set a standard of 1 ppm PCBs and cPAHs in the Riggs Brook
sediments based in part on input from US Fish & Wildlife Service (USFWS). However, it was
agreed by all parties, including USFWS, that the negative short-term impacts to the wetlands
ecology outweighed the removal of sediments to that level. A trigger level of 5 ppm PCBs for
further action was therefore established As stated in the 1989 ROD, "if an increase in the
current PCB sediment levels occurs above the 5 ppm threshold and/or the fish tissue samples are
found to be greater than 2 ppm, then a more rigorous sampling effort of such contamination will
be conducted to determine the need for and/or extent of further remedial actions to be
undertaken within Riggs Brook, if any." (ROD, page 47) This in fact occurred in 1997 when
soil and sediment above 5 ppm PCBs were removed simultaneously with the ongoing SCRA,
and again in 1999 and 2000 when additional samples were collected. The most recent data
(2001) showed that 35 of 36 sample locations were below the 5 ppm trigger level, and the
majority of the samples were non-detect. Maine DEP requested that this ROD amendment
restate that the target cleanup goal for Riggs Brook sediment remains at 1 ppm PCBs and
cPAHs.
The results from two biota sampling events (1997 and 2000), demonstrate that concentrations of
PCBs detected in biota have not exceeded the ROD target level of 2 ppm, and in fact have all
been below 1 ppm.
V. DESCRIPTION OF CHANGES TO THE 1989 ROD
1. DESCRIPTION OF 1989 REMEDY
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The remedy selected by the 1989 ROD was developed to satisfy the following five remedial
action objectives (RAO):
reduce public health and environmental risks from direct contact with contaminated
soils,
reduce public health risks from inhalations of PCB vapors,
reduce future health risks from ingestion of contaminated groundwater found on the site,
reduce public health risks from ingestion of PCB-contaminated fish from Riggs Brook,
and
reduce risks to aquatic and terrestrial wildlife from exposure to contaminated sediments.
The first two RAO were achieved with the completion of the source control remedial action in
1997. The soil clean-up began in 1996 with the cleaning, demolition, and off-site disposal of
the barn situated along Route 17, and other site preparation activities. The second phase of the
soil cleanup was completed in 1997. These activities included the collection and off-site
disposal of lagoon water, and the excavation and off-site disposal of nearly 20,000 tons of soil.
An additional 3000 to 4000 tons of soils with PCBs or PAHs concentrations between 1 and 10
ppm were placed within the designated area onsite. This area was then covered with a minimum
of one foot of clean fill brought in from offsite. The entire site was then graded. Drainage
patterns and the on-site wetlands were restored. An additional 0.4 acre of wetlands was created
in the former lagoons as replacement for wetlands lost as a result of the clean-up activities.
Laboratory tests of samples collected from the bottom and perimeter of the excavation
demonstrated that the excavation had removed the contaminated soil to the performance
standards set in the 1994 BSD. Combined with the operation and maintenance of the soil cover
and monitoring points, the risk to public health from contact with the soil and inhalation of
vapors are addressed.
A more complete description of the source control activities can be found in the September 1998
SCRA report.
The last two RAO have been achieved through the monitoring of sediments, analysis offish
tissue for PCB accumulation, and the 1997 excavation of sediment in three separate locations
where concentrations exceeded the trigger level.
A more complete description of the wetlands restoration, hot spot excavations, and Riggs Brook
monitoring can be found in the Wetlands Construction Monitoring reports for 1997-2000 (The
Smart Associates) and the Riggs Brook Sediment and Biota Monitoring reports for 1999 - 2001
(Woodard & Curran).
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The groundwater remedy selected in the 1989 ROD included pumping wells, a treatment system,
and a network of monitoring wells to track contamination levels. The intent was to pump and
then treat groundwater which contained dissolved PCBs and VOCs and thereby restore the
quality of the groundwater.
In 1992, a bedrock pump test was performed. During the test a separate phase oil layer up to
three and half feet thick was pulled into three bedrock wells in Transformer Work Area II (TWA
II - see Figure 2). This was the first time that separate phase oil had been detected in the
bedrock. As a result, additional monitoring wells were installed to determine how far the oil
extended. No additional oil was discovered and it was concluded that the extent of free oil in the
bedrock was limited.
The next stage of the groundwater remedy took place in 1996-97. About 28 gallons of PCB-
laden oil were pumped out of the shallow bedrock during this period. The pumping system was
shut down when oil was no longer recovered.
From 1997 to 2001, CMP continued to recover oil from wells by using absorbent materials to
remove any oil which accumulated in the wells. A little under seven gallons of PCB-laden oil
was recovered during this period from wells in TWA II.
A third effort at oil recovery took place from August to October 2001. Five wells in TWA II
were alternately pumped. Just under 20 gallons of PCB-laden oil were recovered. This pumping
effort was also shut down when oil was no longer pulled into the system.
2. CHANGES TO THE 1989 REMEDY
In April 2002, CMP submitted an evaluation of the technical practicability of restoring the
groundwater at the O'Connor site to drinking water quality within a reasonable period of time.
This evaluation concluded that because of the geology and hydrology at the site, there were no
technologies which could accomplish this objective (the third RAO in the 1989 ROD). The
evaluation was resubmitted in June 2002 following EPA and Maine DEP comments. EPA, with
concurrence from Maine DEP, approved the June 2002 report.
This ROD amendment for OU-2 selects a remedy consisting of institutional controls, active oil
recovery, long-term monitoring of groundwater, and five-year reviews. This ROD amendment
recognizes the technical impracticability of achieving the third RAO (reduction of future health
risks from ingestion of contaminated groundwater found on the site) within a reasonable time
frame. It establishes a technical impracticability zone for a portion of the site where state and
federal drinking water standards are waived.
A comparison of the original 1989 remedy for groundwater and the modified remedy for OU-2
is provided in Table 1.
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VI. SUMMARY OF SITE CHARACTERISTICS
This section of the report provides a summary of the groundwater data at the site, starting from
the upgradient position at MW-101A/B, through the upland marsh area, the TI zone (TWA II
and VER), the area downgradient of the TI zone (MOM wells), and to the groundwater
discharge area represented by MW-106A/B. See figure 3 for monitoring well locations.
Groundwater cleanup standards established in the ROD include total PCBs at 0.5 jig/L, benzene
at 5 |ig/L and 1,4-dichlorobenzene at 27 jig/L. In addition, based on the ARARs review
discussed in Section VIII. 1 of this ROD amendment, five other VOCs were identified which
since the 1989 ROD have had ARARs established and for which a TI Waiver will apply. These
ARARs include Maximum Contaminants Levels (MCLs) and Maine Maximum Exposure
Guidelines (MEGs) for eight VOCs and PCBs. For each of these five compounds, the MEG is
either the same or lower than the respective MCL.
1. Upgradient Location
Monitoring wells MW-101A and MW-101B are upgradient of the TWAs, located near the
western boundary of the site in an upland area. These wells were installed during the RI to
provide an indication of regional water quality as groundwater flows easterly beneath the site
toward Riggs Brook. MW-101A monitors groundwater in the overburden soil and MW-101B
monitors the bedrock groundwater. Annual sampling of these wells since 1996 has not detected
any PCBs or VOCs.
2. Upland Marsh Area
An investigation to determine the presence and extent of oil in the desiccated clay in the Upland
Marsh area was completed in 1998 and 1999. The intent of the investigation was to determine
the likely source of oil that accumulated in a wetland piezometer (UM-1) in the Upland Marsh
and to determine the distribution of any additional residual oil in that area. The investigation
involved completing 19 GeoProbe borings with continuous sampling (figure 11). The samples
were retrieved and logged with respect to the soil type and tested for oil. Based on the GeoProbe
borings, the soil stratigraphy and extent of residual oil was determined in the Upland Marsh.
The brown desiccated clay has a blocky fracture structure where oil resides in both vertical and
horizontal fractures. A slight to moderate oil sheen was found coming from discrete fractures in
the clay. All oil found resided as a residual coating on the clay fractures walls. The results of
the analysis indicated that PCBs in soils around and including the fractures were found to range
from non-detect (ND) to 1000 |ig/kg (i.e. from ND to 1 ppm). The ROD target level for PCBs
in the overall mass of soil outside the Source Control Designated Area, specified during the
source control remedial action, is 1 ppm. Therefore, concentrations of PCBs found in these
samples did not exceed the target level.
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The data collected suggest that the oil, which originated from TWA II during transformer
salvaging operations, ran off the land surface toward the Upland Marsh and infiltrated into the
upper brown desiccated clay during the time that the site was active. Unable to move
downward, both from the underlying soft clay and the lack of the entrance pressures necessary
for an immiscible liquid to overcome surface tension forces, the oil has remained relatively
immobile in the upper clay fractures. In the northern portion of the study area, where the
desiccated clay is in direct contact with the till, there is no evidence that suggests the oil has
migrated along the till/bedrock interface. It appears that the oil has migrated vertically
downward into the clay reaching an equilibrium between surface tension forces imposed by the
clay fracture capillaries, the density considerations of an immiscible liquid in a saturated
medium and a unit infiltration gradient. Very little horizontal movement has occurred at depth
because the horizontal gradient across the site is not great enough to overcome the resisting
forces described above. It is believed that the oil found in the area surrounding UM-1 is
residual in nature and without a significant gradient does not migrate.
3. TI Zone Wells
A. PCBs Data Evaluation
The groundwater from the five wells in the TWA II Area was not sampled in 1996 or 1997
because oil was found in these wells and it was agreed that the wells would not give
representative results of the dissolved concentrations. After 1997, the four groundwater
observation wells (OW-202B, OW-204B, OW-301B, and OW-302B) and the VER extraction
well (RW-101) were sampled quarterly for PCBs and the seven target VOC compounds if oil
was not detected in the wells. However, the results of TWA II well sampling indicated a wide
variation in contaminant concentrations. It was determined that this was due to the presence of
emulsified oil in the well water and associated VOCs in an oil emulsion which was not present
sufficiently to be measured by the interface probe, but was visually detected in the samples and
purge water. The samples taken were not representative of actual dissolved contaminants in the
groundwater.
Table 2 gives the results of PCB data collected from TWA II from 1998 to 2001. The results in
bold print are above the ROD cleanup goal for PCBs of 0.5 jig/L and represent the impact of oil
emulsions in the samples, not dissolved PCBs in groundwater.
Table 2 indicates that two wells, OW-301B and OW-302B continually had PCBs detected at
greater concentrations than the ROD cleanup standard of 0.5 |ig/L. These are the same two wells
that had groundwater that regularly exceeded the VOC cleanup standards. Separate phase oil has
been observed in three other TWA II wells, OW-202B, OW-204B, and the VER extraction well,
RW-101, on an ongoing basis since September 1998.
PCBs were detected at 8,900 |ig/L at OW-302B in December 1998. In April 2001, the
concentration of PCBs at OW-302B was 44 |ig/L. The PCB results at OW-302B have ranged
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from 2.5 to 8,900 |ig/L. Separate phase oil has also been observed in this well over time. In
November 2001, 1.25 feet of oil was measured. The increased thickness of oil in OW-302B in
November 2001 is most likely the result of the operation of the VER system (Phase III) in
September 2001 and extremely low water table elevation. The observed oil is likely responsible
for the PCB concentrations detected at OW-302B.
The historic PCB results report can be found in the June 2002 Technical Impracticability
Evaluation Report, Appendix C.
B. VOC Data Evaluation
The ROD cleanup goals are 5 jig/L for benzene and 27 jig/L for 1,4-dichlorobenzene.
Additional ARARs for which a TI waiver will apply are listed in Table 3.
Benzene concentrations from the groundwater in TWA II wells ranged from 0 to 8.0 |ig/L
between 1998 and 2001. Benzene concentrations from OW-302B were regularly (6/98, 9/98,
12/98, and 6/99) detected at 6.0 |ig/L, which is 1 |ig/L over the MCL/MEG. The last sampling
event at this well detected benzene at 8.0 jig/L in April 2001. No other TWA II wells exhibited
an exceedance of the benzene MCL/MEG.
The Maine MEG for 1, 4-dichlorobenzene (27 |ig/L) was regularly exceeded at both OW-301B
and OW-302B between 1998 and 2001. The 1,4-dichlorobenzene results at these two wells
ranged from 89-720 |ig/L. Several other target VOCs were also detected in OW-301B and OW-
302B. The two TWA II wells with the exceedance for VOCs are located close together in the
center of TWA II. These two wells are located immediately adjacent to well OW-202B, which
was used for the 1992 pumping test and is responsible for drawing oil into the bedrock aquifer.
1,4-dichlorobenzene was also detected in low concentrations (below the MEG) in observation
wells OW-204B (up to 0.7 |ig/L), OW-202B (up to 20 |ig/L) and the VER well RW-101 (up to
13
The TI evaluation of ARARs identified MCLs/MEGs for five other VOCs which have been
detected in the groundwater. In addition, another VOC, 1,2,3-trichlorobenzene, has been
detected but does not have either an MCL or MEG. Three of these VOCs, chlorobenzene, 1,2-
dichlorobenzene, and 1,2,4-trichlorobenzene, were detected in the RI sampling. Five of these
other VOCs were detected in the TWA II wells between 1998 and 2001. Concentrations of
chlorobenzene ranged from 4 to 240 |ig/L at OW-301B and OW-302B, exceeding the Maine
MEG of 47 |ig/L. 1,2-Dichlorobenzene and 1, 3 -Di chlorobenzene (ME MEG of 85 |ig/L) were
detected at OW-301B and OW-302B at concentrations ranging from 3-210 |ig/L and 2-160 |ig/L,
respectively. These compounds were detected at relatively low concentrations at the other TWA
II wells.
Concentrations of 1,2,4-trichlorobenzene have been detected above the Maine MEG of 70 jig/L
at OW-202B and OW-301B at concentrations ranging from 3-610 |ig/L, and ranging as high as
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3200 |ig/L at OW-302B.
The historic VOC results are included in the June 2002 Technical Impracticability Evaluation
Report, Appendix D.
C. VER Operation
The vacuum-enhanced recovery system (VER) has been operated for three periods of time
following post-ROD pilot tests. The total amount of oil recovered from the five TWA II wells
since their installation is approximately 85.2 gallons. A summary of oil recovered from the
TWA II wells is presented in Table 4.
Five wells (OW-202B, OW-204B, OW-301B, OW-302B and RW-101) in the former TWA II
Area and piezometer UM-1 have been monitored for groundwater elevation and oil thickness on
a monthly basis since 1998. Whenever oil was detected in a well, an absorbent sock was
lowered into the well to adsorb and remove the oil. Since the last oil recovery effort in the fall
2001, 1.25 feet of oil accumulated in OW-302B and was removed using absorbent socks.
4. Management of Migration
A. PCB Data Evaluation
Included in this section is a discussion of those wells which are located in the area downgradient
of the TI zone. Aside from a few initial sampling events (prior to 1994) where elevated
concentrations of PCBs may have resulted from PCB adsorption onto soil particles in the
groundwater samples, concentrations of PCBs in groundwater samples collected from wells
outside of the TWA II Area have not exceeded the 1989 ROD target cleanup level for PCBs (0.5
In March 1999, the groundwater samples from six MOM monitoring wells were analyzed using
USEPA Modified Method 680 for total homologue PCBs. The results of the 680 analyses are
summarized in Table 5. Concentrations of PCBs were below the ROD target cleanup level. As
stated in Section VIII. 1., current ARARs have been reviewed and concentrations of PCBs at
several wells are at or slightly above the 1992 Maine MEG of 0.05 |ig/L. Future analysis of
groundwater from MOM wells will be done using a lower detection limit, to determine if
groundwater outside the TI Zone (see Figure 3) meets the 1992 Maine MEG of 0.05 |ig/L.
B. VOC Data Evaluation
This section will discuss the VOC results compared to federal MCLs and Maine MEGs (see
Figure 2 for well locations).
The VOC results from MW-104B and OW-201B indicate the presence of low to moderate levels
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of VOCs in the bedrock at these locations. The MEG for 1,4-dichlorobenzene (27 |ig/L) has
been exceeded at both wells. Prior to June 1998, the concentration of 1,4-dichlorobenzene
ranged from 26-91 |ig/L in MW-104B and 25-55 |ig/L in MW-201B. Since then, the
concentration of 1,4-dichlorobenzene has been consistently between 20-40 |ig/L in MW-104B
and 20-36 |ig/L in MW-201B. These are reductions and if these decreasing trends continue, the
concentrations of 1,4-dichlorobenzene at OW-201B and MW-104B are expected to be
consistently below the MEG in the near future.
For the VOCs with post-ROD MCLs/MEGs, 1,2-dichlorobenzene exceeded the MEG of 85 |ig/l
at these wells prior to 1997, but has been below the MEG since, and 1,3-dichlorobenzene has not
exceeded its MEG of 85 |ig/L. Concentrations of benzene, chlorobenzene, 1,2,3-
trichlorobenzene and 1,2,4-trichlorobenzene have been very low to moderate and have not
exceeded MEGs at MW-104B and OW-201B, except for 1,2,4-tri chlorobenzene prior to 1995.
Results of analysis of groundwater from monitoring wells MW-507A and MW-508B, placed in
the bedrock trough, indicate the presence of five VOCs in MW-507A and four VOCs in MW-
508B. The relative VOC concentrations are generally higher in the shallow groundwater
monitored by MW-507A. Monitoring well MW-507A is located in a bedrock trough and
screened in the till/bedrock surface specifically to monitor VOC concentrations in the primary
migration pathway where contaminated groundwater from the former TWA source areas flows
slowly in a southeasterly direction. Monitoring well MW-508B was installed into the bedrock to
monitor VOC concentrations in the secondary bedrock migration pathway. The concentrations
of 1,4-dichlorobenzene in MW-507A ranged from ND-81 |ig/L in the past five years.
The concentrations of 1,4-dichlorobenzene at MW-503, downgradient of MW-507A, are much
lower (ND-8 |ig/L) than at MW-507A. The same decrease in concentrations was observed for
1,2-dichlorobenzene and 1,3-dichlorobenzene. This reduction in VOC concentrations between
MW-507A and MW-502/MW-503 indicates that very little contaminant mass is flowing past the
bedrock trough area. Concentrations of benzene, chlorobenzene, 1,2,3-trichlorobenzene and
1,2,4-tri chlorobenzene were detected at low concentrations in all four wells MW-507A, MW-
508B, MW-502 and MW-503.
In addition, concentrations of VOCs at MW-501 (downgradient of TWA III) and MW-511A
(downgradient of TWA I) have been non detect to trace levels.
Based on this evaluation of VOC data, wells along the boundary of the TI zone are in attainment
of federal MCLs and Maine MEGs (MW-501, MW-502, MW-503 and MW-510A). These
decreasing trends in VOC concentrations are likely due to the successful completion of the
SCRA and removal of residual oil with the VER system, and are expected to continue.
C. Discharge Zone, MW-106A/B
Concentrations of PCBs in groundwater samples collected from MW-106A/B have not exceeded
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the ROD target cleanup level for PCBs (0.5 |ig/L).
The VOC concentrations from the groundwater in MW-106A and MW-106B have been
relatively consistent over the past six years. MW-106A monitors the overburden aquifer at this
location and flows under low artesian conditions during periods of high groundwater. Non-
detect to trace concentrations of the seven VOCs have been detected. The deeper well (MW-
106B), flows under artesian conditions most of the year, and is believed to be intercepting a
portion of the bedrock groundwater migrating from the site and represents the bedrock water
quality. Low levels of six VOC compounds are regularly detected at MW-106B. The
concentrations of 1,2,3-Trichlorobenzene and 1,2,4-Trichlorobenzene have generally been
decreasing atMW-106B since March 1997 and March 1995, respectively, with more significant
decreases in 2000 and 2001.
The 1,2,4-trichlorobenzene concentrations are well below the MCL and 1992 MEG of 70 |ig/L.
(There is no MCL or MEG for 1,2,3-trichlorobenzene. However, it can be generally assumed
that its risk factors would be similar to 1,2,4-trichlorobenzene, and the detected concentrations
of 1,2,3-trichlorobenzene are also well below 70 |ig/L.)
Historic PCBs and VOCs results of the MOM monitoring conducted between October 1995 and
September 2001 and prior analytical results are included in the June 2002 Technical
Impracticability Evaluation report, Appendices G and H.
VII. SUMMARY OF SITE RISKS
Human health and environmental risk assessments were conducted as part of the Feasibility
Study leading up to the 1989 Record of Decision. These assessments identified seven exposure
scenarios as posing current and potential future risks to human health or the environment. (ROD,
page 13) Of these seven, five were associated with the soils and lagoon sediments, one with
ingestion offish from Riggs Brook, and one with ingestion of groundwater from the bedrock:
direct contact with soils by children;
inhalation of vapors from surface soils;
ingestion of fish caught in Riggs Brook;
future direct contact with soils by on-site inhabitants
future direct contact with sediments in the lower lagoon by children; and
future inhalation of vapors by on-site inhabitants; and;
future ingestion of groundwater from within the bedrock.
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Following the completion of the SCRA, only two potential exposure scenarios remain. They are
future ingestion of groundwater from within the bedrock, and ingestion offish caught in Riggs
Brook.
A site-wide five-year review was performed in 2002 for all three operable units. The exposure
assumptions, toxicity data, and cleanup levels for groundwater were evaluated as part of the
overall protectiveness determination. The review did not identify any changes in the exposure
assumptions, found the toxicity data have had only minimal changes (some slightly increasing,
others decreasing) and concluded that there had been no significant change in site risks. (EPA,
2002) Since the 1989 ROD, the State of Maine has promulgated by reference the 1992 MEGs.
The 1992 MEG for PCBs is 0.05 ppb, an order of magnitude lower than the MCL of 0.5 ppb,
which is the ROD standard. Except for the immediate area surrounding and including TWA II,
PCB concentrations in the groundwater were close to this standard (0.02 to 0.09 ppb in the one
sampling event where a lower detection limit was reached). The Restrictive Covenant currently
ensures that there will be no exposure to the groundwater beneath the site.
VIII. TECHNICAL IMPRACTICABILITY DETERMINATION
The continued presence of separate phase PCB-laden oil four years after the successful
completion of the source control remedial action suggested restoration of the groundwater using
the VER or a groundwater extraction and treatment system is not possible. Consequently, EPA,
with concurrence from Maine DEP, agreed to a proposal by CMP to evaluate whether it would
be technically practicable to restore contaminated groundwater to drinking water standards,
including MCLs and MEGs.
Restoration of contaminated groundwater is one of the primary objectives of the Superfund
program. The NCP states that "EPA expects to return usable ground waters to their beneficial
uses wherever practicable, within a time frame that is reasonable given the particular
circumstances of the site." Section 300.430(a)(l)(iii)(F) of the NCP. Generally, restoration
cleanup levels in the Superfund program are established by applicable or relevant and
appropriate requirements (ARARs), such as the use of federal or state standards for drinking
water quality.
Further, under CERCLA, an alternative selected to address contamination at a site must achieve
the ARARs identified for the action, or provide the basis for waiving the ARARs. ARARs may
be waived for any of six reasons, including where compliance with the requirement is
technically impracticable from an engineering perspective. See Section 121(d)(4) of CERCLA
and Section 300.430(f)(l)(ii)(C) of the NCP. The primary considerations for determining the
technical impracticability (TI) of achieving ARARs are engineering feasibility and reliability.
See NCP Preamble, 55 Fed. Reg. 8748 (March 8, 1990).
EPA's Guidance for Evaluating the Technical Impracticability of Ground-Water Restoration.
(OSWERDir. 9234.2-25, September 1993, Interim Final) specifies the following components as
necessary for a TI evaluation:
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1. Specific ARARs or media standard for which TI determinations are sought;
2. Spatial area over which the TI decision will apply;
3. Conceptual model that describes site geology, hydrogeology, groundwater contamination
sources, fate and transport;
4. An evaluation of the restoration potential, including predictive analyses of the
timeframes to attain required cleanup levels and a demonstration that no other remedial
technologies could be capable of achieving groundwater restoration; and
5. Cost estimates of the proposed remedy options.
Following a TI evaluation, EPA's goal of restoring contaminated groundwater within a
reasonable time frame will be modified where restoration is found to be technically
impracticable. In such cases, EPA will select an alternative remedial strategy that is technically
practicable, protective of human health and the environment, and satisfies the requirements of
CERCLA and the NCP. Where groundwater ARARs are waived at a Superfund site due to
technical impracticability, EPA's general expectations are to prevent further migration of the
contaminated groundwater plume, prevent exposure to the contaminated groundwater, and
evaluate further risk reduction measures as appropriate. See Section 300.430(a)(l)(iii)(F) of the
NCP. These expectations should be evaluated along with the nine remedy selection criteria
provided in the NCP.
The results of the TI Evaluation for O'Connor are provided below.
1. ARARs
Under the EPA Groundwater Protection Strategy, EPA has classified the aquifer beneath the site
as a Class II aquifer, i.e.. groundwater which potentially could be a source for drinking water in
the future. Thus, Maximum Contaminant Levels (MCLs), and non-zero Maximum Contaminant
Level Goals (MCLGs), established under the Safe Drinking water Act, are ARARs.
The state Maximum Exposure Guidelines (MEGs) are chemical-specific ARARs that are health-
based guidelines intended to determine drinking water quality for private residential wells.
MEGs are relevant and appropriate requirements in establishing groundwater remediation goals.
The MCLs and MEGs for which a technical impracticability waiver will apply are as follows:
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Table 3: Chemical-Specific ARARs for TI Waiver
Contaminant
Of Concern
Benzene
1,4-
Dichlorobenzene
PCBs1
Chlorobenzene
1,2-
Di chl orob enzene
1,3-
Di chl orob enzene
1,2,3-
Trichlorobenzene
1,2,4-
Trichlorobenzene
1,3,5-
Trichlorohenzene
2001 Maximum
Groundwater
Concentration
(Hg/L) and Location
8 - OW-302B
720 - OW-302B
44 . QW-302B
240 - OW-302B
210 - OW-302B
160 - OW-302B
98 -OW-302B
770 - OW-302B
not analyzed for
MCL
(Hg/L)
5
75
0.5
100
600
NS
NS
70
NS
1992
MEG
(Hg/L)
5
27
0.05
47
85
85
NS
70
40
1989 ROD Target
Cleanup Levels
(Mg/L)
5
27
0.5
no ROD standard
no ROD standard
no ROD standard
no ROD standard
no ROD standard
no ROD standard
1 detection limit varies with location and are generally greater than the 1992 MEG.
NS - no standard
2. Spatial Extent of the Technical Impracticability Zone
This section describes the horizontal and vertical extent over which the Technical
Impracticability decision would apply (TI Zone). This includes the portion of groundwater
known to contain VOCs above federal MCLs and State MEGs that would require substantial
timeframes to remediate using currently available technologies.
The proposed TI Zone horizontally encompasses the TWA II Area and the area associated with
shallow groundwater flow to the south of the TWA II Area. Vertically, the proposed TI Zone
extends into bedrock. The TI Zone, as shown in Figure 3, includes areas where VOCs and PCBs
are present in groundwater at concentrations above ROD target cleanup goals and current MCLs
and MEGs. This is principally the TWA-II area. Overall, analytical results from monitoring
wells MW-501, MW-502, MW-503, MW-505, MW-509A, MW-510A, and MW-511A, located
along the boundary of the TI Zone, show that concentrations of the seven VOCs and PCBs
detected during semi-annual groundwater monitoring events are below ROD target cleanup goals
and current MCLs and MEGs.
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In review of the TI evaluation report, Maine DEP noted that the TI zone included most of the
former upper lagoon. EPA recognizes, just as the boundary of the Designated Area is being
simplified in this ROD Amendment so that it may be easily identified, the TI zone has also been
established in part to allow for its easy identification while onsite. Consequently, while the
upper lagoon was successfully remediated during the SCRA, a portion of it falls within the TI
zone as a result of simplifying the TI boundary.
3. Conceptual Model
The conceptual model serves as a foundation for evaluating the restoration potential of the site
and, thereby assessing the technical impracticability as well. It includes the site geology and
hydrogeology, nature and extent of Contaminants of Concern in groundwater, fate and transport
processes, and current or potential receptors. This conceptual model has been developed through
review of reports of previous investigations and the visual inspection of subsurface materials
during source control work. The SCRA involved the excavation of a significant portion of the
site's overburden, and, in some places, exposure of the bedrock surface.
This summary of the conceptual model was presented in the June 2002 Technical
Impracticability Evaluation report.
A. Site Geology and Hydrogeology
A summary of the geology and hydrogeology for the overburden and bedrock at the site is
provided below.
1. Overburden Geology
Soil materials on the site include glacial marine silts and clays and glacial till overlying bedrock.
The upper clay unit has two strati graphic members: an upper, stiff, desiccated brown member
and a lower, soft, gray member. The upper brown member which typically makes up the upper
10 to 20 feet of the clay unit, is blocky and highly fractured. The lower gray member is absent
or discontinuous in the upland areas, where total overburden thickness thins to less than 20 feet.
The clay tends to be absent only in areas of shallow bedrock.
The till is discontinuous, varying in thickness from 0 to approximately 42 feet (B-503). The till
ranges from a coarse granular material overlying the shallow bedrock in the northern and
western portions of the site, to thick, dense, fine-grained soils overlying the deeper bedrock in
the central and eastern portions of the site. In the TWA II Area, the till is approximately 0 to 9
feet thick. The till is essentially absent along the axis of the bedrock ridge from the central to
the northern portion of the site. The changes in the observed textures of till are inferred to result
from weathering.
Figure 7 shows the location of three geologic cross sections across the site. Figure 8, Figure 9,
and Figure 10 are the geologic cross sections showing the inferred soil stratigraphy and bedrock
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morphology. The stratigraphic elevations have been inferred from the borings represented on
the profiles. The inferred geologic stratigraphy is the result of the MOM Additional
Investigations Report (W&C 1996a) and existing borings on the site prior to 1996.
The till/bedrock interface is the primary migration pathway of contaminants. The results from
several wells, including B-506, B-510, B-514, and MW-504, indicate a relatively highly
conductive water-bearing zone along the till/bedrock interface. In each of these borings, very
little water was observed during the drilling process until the drill bit penetrated the lower 2 to 3
feet of the till immediately above the bedrock surface. The potentiometric surface in each of
these borings was several feet higher than the permeable zone, indicating a confined condition.
The permeable zone associated with the till/bedrock interface could be the result of an erosional
water-worked environment in the initial stages of till deposition.
The soil stratigraphy in the Upland Marsh area and TWA II Area was further refined during an
Upland Marsh investigation conducted to identify the presence and distribution of oil detected in
an Upland Marsh piezometer UM-1. This study helped refine the hydrogeology in the TWA II
Area and the hydrogeologic interaction of the desiccated clay with the till/bedrock migration
pathway.
The stratigraphy of the soil material in the Upland Marsh area consists of approximately 4 to 10
feet of desiccated brown clay overlying approximately 1.5 to 7 feet of soft, unfractured gray clay
that overlies 2 to 4 feet of till directly in contact with bedrock. These different layers pinch out
in areas of shallow bedrock (GeoProbe boring G-14). Groundwater is confined in the till and
predominately moves along the till/bedrock interface. Surface water infiltrates into the fractures
in the brown clay and is quasi-perched on top of the soft clay, making itself available for
evapotranspiration. Based on historic water elevation data, the quasi-perched water table in the
brown clay fluctuates as much as 6 to 8 feet during the year. Figure 11 shows a plan view of the
site with the GeoProbe locations and the location of three cross section lines. Figure 12, Figure
13, and Figure 14 are the geologic cross sections through the Upland Marsh area depicting the
stratigraphy, original ground surface prior to source control, and the existing ground surface
after source control.
In general, the thickest portions of the desiccated clay were in the Upland Marsh area where the
site topography flattens (G-8, G-9). The stratigraphy remains relatively consistent except in the
northern portion of the study area (probes G-12, G-13, G-14, G-15, and G-16) where the
bedrock surface rises and the soft clay pinches out. See Figure 13 and Figure 14. In this area
the desiccated clay is in contact with the till.
2. Bedrock Geology
The shallow and deep bedrock flow system at the site was studied in several pre- and post-RGB
investigations. The 1996 field study investigated the bedrock surface in an effort to understand
the potential migration pathway along the top of the bedrock. The inferred bedrock surface
elevation is depicted in Figure 15. The bedrock surface morphology can also be viewed on the
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geologic profiles on Figures 8-10 and Figures 12-14. The bedrock surface was verified during
source control work, in locations where soil was excavated down to the bedrock surface.
The bedrock surface consists of a hard, minimally weathered quartz monzonite. Drilling logs
from former investigations indicate metasedimentary bedrock interspersed with the quartz
monzonite on the eastern portion of the site (MW-406B) suggesting a contact between the
intruded monsonite and the surrounding metasedimentary rock.
The bedrock structural features were evaluated both locally and regionally in the
Photogrammetric Analysis and Outcrop Study (E. C. Jordan, 1986). This evaluation utilized
photogrammetric analysis including the examination of aerial photographs and radar imagery.
Additionally, five bedrock outcrops were examined in the vicinity of the site. This study
included information regarding the existence and orientation of bedrock fractures present in the
crystalline rocks in the area. Results of this study determined that the regional structural
orientation is in a northeast-southwest orientation. Three prominent NE/SW lineaments were
identified in the vicinity of the site in the E. C. Jordan study. The study also determined that the
most common strike orientation was NE/SW.
The Inferred Bedrock Surface map provided in Figure 15 shows that the bedrock ridge is
oriented generally on a northeast-southwest axis coincident with the previously identified
regional structural orientation. The bedrock ridge is a natural feature that has been scarred and
rounded by the last glacial advance and retreat. It is a quartz monzonite and as such has no
bedding or structural folding orientation. The major structural trends outlined in the E.G. Jordan
study refer to a NE/SW structural orientation associated with regional tectonic compression
history of the coast of Maine (refer to the bedrock geologic map of Maine). The monzonite
intrusive is part of the Devonian intrusives which intruded the country rock of the region and is
generally elongated parallel to bedding strike of the country rock. This may have had influence
on the cooling history and post placement fracturing of the monzonite, but is believed to have no
direct influence on fracturing of the intrusive body and thus no influence on groundwater
movement.
Conclusions of the 1986 E.G. Jordan Study are as follows:
regional and local strike orientation is northeast/southwest;
exfoliation type of near-horizontal fracture surfaces are uniform and widespread
throughout the area,
"fractures will have the most significant impact on groundwater flow patterns within the
rock mass";
groundwater flow from the site is expected to be generally coincident with topography,
and
the potential exists for a northeast-southwest flow barrier or groundwater sink in the
vicinity of Riggs Brook.
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The bedrock drilling in all investigations indicated mostly competent rock with very few
recognizable fractures. The rate of bedrock drilling was unusually slow. Occasionally, at
random depths below the bedrock surface, the downhole drilling equipment would advance
rapidly for 0.2 to 0.4 feet, indicating the existence of a weak weathered layer or fracture in the
bedrock. After encountering a weak layer in the bedrock or a bedrock fracture, an increase in
the available formation water would be observed, indicating the presence of groundwater in the
fractures in the upper bedrock. During source control work where the bedrock surface was
exposed during soil removal, the bedrock appeared very competent. Very few fractures
appeared to be exposed along the bedrock surface and none appeared to be able to supply any
significant amount of recharge to the bedrock flow system. Bedrock outcrops are found in the
area of TWA II and to the south in the vicinity of TWA I (refer to Figure 2).
Generally, the bedrock forms a saddle, with the center of the saddle immediately northeast of the
upper lagoon (Figure 2). The center of the saddle forms a trough filled with till and the
overlying marine clay. Figure 7 contains geologic cross sections depicting the bedrock trough in
the center of the saddle. Figure 9 is a cross section along the center of the saddle and Figure 10
shows the bedrock ridge to the northeast of the center of the saddle. The till is absent along the
top ridge and marine clay is in direct contact with bedrock.
The limited fracture network of the bedrock flow system and limited available recharge from the
overburden limits flow in the bedrock aquifer. Recharge to the bedrock from the overburden is
limited by the low permeability overburden soils and lack of shallow groundwater in the
overburden. Because the bedrock is tight, limited flow moves through the bedrock system.
3. Groundwater Flow in the Overburden and Bedrock Flow System
The principal groundwater migration pathway on the site is a discrete zone within the till along
the top of the bedrock surface. The groundwater flow direction is a subdued reflection of the
bedrock surface. Figure 16 shows the inferred groundwater flow direction superimposed on the
bedrock surface map. Groundwater flow from the large recharge basin (Upland Marsh) to the
northwest of the source control area is confined and channeled through the bedrock trough in the
center of the bedrock saddle. The reworked till along the bedrock surface is the primary
migration pathway leaving the source area. The bedrock ridge where the till is absent (refer to
Figure 10) inhibits movement of the shallow groundwater flow from the source control area to
the southeast toward Riggs Brook. The upper till and clay tend to confine the groundwater, not
allowing flow over the bedrock ridge as depicted in Figure 16, and forcing flow through the
bedrock trough. On the northwest side of the ridge and within the bedrock trough, groundwater
under pressure was observed during the drilling of borings B-514, MW-504, B-510, and B-506.
On the southeast side of the ridge, i.e., B-515, B-509, MW-501, B-508, and B-504 (Figure 16),
very little groundwater was observed and the groundwater was very slow to recharge the wells.
Under steady-state conditions, groundwater in this area was less than 1-2 feet above the bedrock
surface.
Conceptually, precipitation recharges the fractured clay, till, and bedrock (where exposed at the
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surface), and flows within the shallow groundwater flow regime. Under static, non-stressed
conditions, there is very little vertical mixing between the overburden and bedrock groundwater
in the immediate area surrounding the transformer work areas. Although a downward vertical
gradient exists, the relatively low vertical permeability of the bedrock inhibits vertical migration.
Groundwater recharge to the fill soils used to re-grade the site following the SCRA does not
change the overall groundwater flow patterns.
The bedrock ridge inhibits the southeasterly flow of shallow groundwater. The only water
available to flow on the southeast side of the ridge comes from recharge through the clay surface
soils and groundwater discharging from the bedrock. Both sources of recharge to the
till/bedrock migration pathway southeast of the bedrock ridge are very limited, leaving
somewhat dry conditions within this migration pathway. The contaminant distribution along the
till/bedrock interface and the recharge of the monitoring wells in this area, as described above,
supports this understanding. Long-term monitoring of shallow overburden monitoring wells,
MW-501 and MW-502, indicates very little overburden groundwater in this area of the site.
The bedrock flow regime has very little water in storage. The exfoliated fracture network is far-
reaching and derives its recharge from the upland areas surrounding the TWAs. The vertical
permeability of the bedrock is believed to be very low, creating the "quasi" perched condition of
the shallow overburden groundwater flow system. Over most of the site, the bedrock
groundwater is under a confined condition. In the southeastern end of the site the potentiometric
surface of the bedrock groundwater is above the ground surface. MW-106B is in the
southeastern portion of the site and is a free-flowing artesian well. As an artesian well, it creates
a pressure release, and provides a condition for contaminants that have entered the bedrock flow
regime to discharge to the ground surface.
The overburden groundwater is "quasi" perched; releasing groundwater from storage to supply
recharge to the bedrock fractures where possible. The horizontal permeability in the upper
bedrock zone is higher than the vertical permeability. This is evident when comparing the
potentiometric surface of the bedrock and overburden. Groundwater elevation data including
potentiometric surface maps and time series plots at four well pairs are provided in the June
2002 Technical Impracticability Evaluation report. Although most of the bedrock wells are open
holes (i.e., no screened zones set) the well couples (i.e., MW-103 A, B) are separated by a casing
advanced into rock. Typically, the overburden wells are set on top of the bedrock surface while
the bedrock wells are open holes with grouted casing approximately five feet or less into the
bedrock surface. Historically, the difference in groundwater potentials across this relatively
short distance has been on the order of 1 to 2 feet. This downward gradient in the source control
area is likely due to the low vertical permeability of the bedrock and supports the "quasi"
perched understanding of the vertical groundwater flow from the overburden into the bedrock.
The vertical gradient is downward over most of the site. The vertical gradient is downward at
well pair MW-507A/MW-508B. Prior to the abandonment of well pairs MW-102A/B, MW-
105A/B and MW-401A/B for Source Control, these wells exhibited downward vertical
gradients.
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The vertical gradient is upward at the location of well pair MW-106A/B. This well pair is
located adjacent to Riggs Brook and monitors the confined bedrock flow system downgradient
from the site. Bedrock at this location drops considerably in elevation and is confined by
approximately 50 feet of clay soils confining the upland flow from the site to Riggs Brook.
The horizontal gradients have been calculated for both the overburden aquifer and the bedrock
aquifer. The gradients are similar in both aquifers. In the upland portions of the site, the
horizontal gradients are approximately 0.01 and 0.024 on the overburden and bedrock aquifers,
respectively. In the steeper area between the Upper Lagoon and the Lower Lagoon, the
horizontal gradients are approximately 0.09 and 0.06 in the overburden and bedrock aquifers,
respectively.
During the 1992 pumping test, the bedrock observation wells (MW-103B, MW-104B, MW-
105B, OW-201B, OW-204B, OW-301B, and OW-302B) responded relatively quickly and, with
time, significant drawdown was observed in bedrock wells as far away as MW-105B. This
indicates that groundwater in storage moved quickly to the pumping well and that recharge
(vertical) from the overburden into the bedrock was slow. Because groundwater was taken from
storage within the bedrock and was vertically inhibited from recharging the bedrock from the
overburden, recharge to the pumping well came predominately from the more regional network
of bedrock fractures. Significant drawdown was observed long distances from the pumping
well. The rapid response observed in the bedrock observation wells during pumping and the
extent of drawdown within the bedrock supports the conceptual understanding that the bedrock
has a far-reaching, interconnected fracture network with a very low density of fractures and thus,
a relatively slow vertical permeability and very little storage.
The large variability in hydraulic properties of the bedrock lends to the conceptual understanding
that the fracture network, although loosely connected, in the bedrock is comprised of very fine
micro fractures that do not yield much water and larger fractures that may yield as much as 1-2
gpm. The bedrock is relatively tight on a site-wide basis, as observed by the perched water
table, visual observations during source control, and bedrock RQD analysis done during the RI.
The bedrock in the lower elevations (near well MW-106B) is confined, and all flow leaving the
site through the bedrock flow system is confined to flow from the site toward Riggs Brook
flowage, then parallel to the Riggs Brook flowage, and eventually discharging to the Kennebec
River Basin. Because of the confined nature of the bedrock system, associated low gradients
across the site, and the low hydraulic conductivities of the bedrock, very little water flows
naturally through the system.
Well MW-106B intersected a deeper fracture that is relatively well connected to the bedrock
fracture network flowing from the site. When well MW-106B was drilled, initial concentrations
of site contaminants at this location were non-detect. Because of the confined conditions and the
fact that well MW-106B was allowed to flow continuously, bedrock flow was short circuited
increasing the gradient from the site and flushing the bedrock flow system toward MW-106B
and eventually up and out of the flow system through this well. As is shown by the chemical
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data from MW-106B, site contaminants increased after the 1992 pump test, when oil was drawn
down into the bedrock. Contaminant concentrations measured at MW-106B, however, never
exceeded ROD cleanup goals. Since then, with groundwater flow under steady state conditions,
the chemical data has shown a steady and consistent decreasing trend. MW-106B has provided a
release of a portion of the bedrock flow system to the ground surface rather than flowing off the
site.
Conceptual depictions of the site hydrogeology before and after source control are presented in
figures 17 and 18.
B. Source of Contamination
An assessment of the groundwater collected from the monitoring wells installed during the RI
indicated the presence of low levels of chlorinated benzenes in monitoring wells downgradient
of TWA II and the Upper Lagoon area (MW-104 and MW-103). PCBs were only detected in
samples collected from MW-104B. From subsequent investigations, it was found that the PCBs
in this well were not in the groundwater but were adsorbed to the soil particles purged from the
well during sampling. The PCBs associated with these particles were the result of drilling
through PCB-contaminated surficial soils. Well MW-104B has only one foot of casing set into
rock. Surficial sediments can easily migrate into the boring during well purging. Metals
detected in on-site wells were generally comparable in concentration to upgradient monitoring
and domestic wells.
The results of the RI sampling work indicated that PCBs from the transformer salvage operations
occurred in three former work areas located in the western portion of the site. These activities
led to uncontrolled releases of oil containing PCBs. In addition, surface erosion had caused
PCBs to migrate a short distance from the work areas. Smaller amounts of PCBs had permeated
into the subsurface soils. Low levels of PCBs were found in surface waters, sediments, and
biota samples. Low levels of other organic and inorganic chemicals were also found in some
media.
Based on the data collected during post-ROD investigations, the primary source of both oil and
chlorobenzenes was the fractures in the clay. Contaminants were held in tension in the fractures
of the clay and, under gravity, slowly migrated to the primary migration pathway along the
till/bedrock surface. Due to the immiscible nature of the oil and its measured specific gravity of
0.91, the oil has remained in the TWA II Area with only small amounts entering into the primary
migration pathway. The chlorobenzenes were able to dissolve into the groundwater and migrate
to a greater degree within the primary migration pathway.
Contaminant migration has not been significant beyond the TWA II area. The following factors
served to control and/or diminish the movement of chemicals in soils and water:
low solubility of PCBs in water;
the strong affinity for PCBs to adhere to soil particles; and
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the presence of thick clay and till deposits in the near surface and deep groundwater regimes.
Precipitation falling on the TWA II Area either runs off as surface water or infiltrates downward
into the overburden. A large portion of the infiltrating water is held in tension in the upper
desiccated clay layer and is quasi-perched on top of the soft clay layer, making itself available
for evapotranspiration. Very little recharge enters the deeper soft clay layers, and even less
infiltrates into the till/bedrock flow system under normal conditions. The desiccated clay
fractures allow a limited migration pathway for water to move downward toward the till/bedrock
migration pathway.
C. Fate and Transport Processes
Contaminants on site migrate with the direction of the groundwater flow. The groundwater flow
direction is a subdued reflection of the bedrock surface (Figure 16). The low vertical
permeability of the bedrock acts to form a "quasi perched" condition along the top of the
bedrock. Although it is believed that the bedrock receives recharge from the upland areas
northeast of the bedrock trough, the vertical permeability of the bedrock is extremely low,
making the bedrock a minor secondary migration pathway. Very little contaminant mass enters
the bedrock flow system through natural groundwater flow and groundwater recharge.
Contaminant mass that is able to enter the bedrock flow regime under static non-stressed
conditions flows within the fracture network of the rock. The storage of groundwater within the
bedrock is extremely low. Recharge to a purged well most likely comes from a significant
distance away from the monitoring well due to the low storage capacity of the bedrock. The
overlying till and marine clay confines the bedrock aquifer at lower elevations. MW-106B has
been left flowing, providing a release for contaminants migrating within the deep bedrock flow
regime and likely represents the groundwater within the bedrock system that would have
otherwise migrated from the site. If MW-106B did not exist, it is believed that bedrock
groundwater discharging from that well would leave the site flowing to the east, where it would
then flow north roughly parallel to the Riggs Brook drainage and towards the regional
groundwater sink of the Kennebec River Basin.
Groundwater within the primary till/bedrock migration pathway moves along the bedrock
surface in the till layer. This migration pathway, like the bedrock flow system, has very low
storage and slow groundwater velocities. Therefore, even in the till/bedrock migration pathway,
very little water is moving. Contaminants entered this flow system by slow recharge from the
overlying clay fracture network. Contaminants in groundwater, once in the till/bedrock
migration pathway, are restricted from flowing southeasterly by the bedrock ridge and flow
toward the natural bedrock trough immediately northeast of the upper lagoon (refer to figure 16).
The bedrock trough acts as a spillway, channeling flow from the upland areas surrounding the
TWAs and releasing it to flow southeasterly toward Riggs Brook. Sentinel monitoring wells
(MW-502 and MW-503), placed along the front edge of contaminants moving through the
bedrock trough, monitor the long-term contaminant migration within the till/bedrock migration
pathway.
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Dissolved VOCs are migrating with the groundwater, however, due to dilution, the
concentrations of VOCs at wells along the boundary of the TI Zone are below the ROD target
cleanup goals and current MCLs and MEGs.
Residual oil containing PCBs and VOCs is held in tension in the desiccation cracks in the clay
and to a limited extent in fractures in the bedrock. Under natural conditions, there is very little
movement of this oil. Concentrations of PCBs in monitoring wells along the boundary of the
proposed TI Zone have been below the ROD target cleanup level of 0.5 |ig/L. However, during
a sampling event conducted in March 1999 using lower detection limits, concentrations of PCBs
were at or slightly above the 1992 Maine MEG of 0.05 |ig/L at MW-503 and MW-106. These
wells are on the boundary or outside of the proposed TI Zone. Continued monitoring will be
conducted to determine if concentrations of PCBs outside the proposed TI Zone meet the 1992
Maine MEG.
4.0 Evaluation of the Restoration Potential
This section evaluates the restoration potential by assessing the performance of remedial actions
previously conducted and those that are ongoing at the site, and evaluates additional technologies
to determine if any could realistically attain drinking water standards for the site within a
reasonable time frame.
Remedial actions have been conducted in three operable units at the site; OU-1 Source Control
Operable Unit, OU-2 Management of Migration Operable Unit, and OU-3 Riggs Brook.
Remedial actions at operable units OU-1 and OU-2 are discussed below, as they are relevant to
the concentration of contaminants in groundwater at the site.
A. Source Control Measures
The SCRA for OU-1 was successfully completed on November 11, 1997. The source
remediation was conducted by sampling and excavating soils and sediments contaminated with
PCBs, lead, and cPAHs above the ROD and ESD target cleanup goals. Approximately 20,000
tons of soil and sediment were removed from the site. Another 3,000 tons were excavated and
consolidated into the designated area (refer to Figure 5) to meet the ESD target cleanup goals.
Soil and sediment in OU-1 were sampled, excavated and re-sampled until there was no
indication of soil containing PCBs, cPAHs or lead above the target cleanup goals. By meeting
the required target cleanup goals for soils and sediment, and removing site surface waters, the
SCRA achieved the remedial action objectives established for the Source Control component in
the 1989 ROD.
Even after the successful completion of the SCRA, some residual oil containing PCBs and VOCs
remains trapped in desiccation cracks in the clay and to a limited extent in fractures in bedrock at
the site. Although residual oil remains in tension in cracks in the clay, when it has been
analyzed in a homogenized clay sample, the concentrations have been below the target cleanup
goals. Therefore, although this remedy was not able to remove all the residual oil, the approved
SCRA
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remediated the source area and met the remedial action objectives stated in the ROD. The
subsequent Upland Marsh study confirmed that the remedial objectives of the SCRA were met,
even though some residual oil remains. The Upland Marsh Study also confirmed that
concentrations of PCBs detected in the dessication cracks in the clay containing oil ranged from
ND to 1 ppm. Therefore, concentrations of PCBs in the fractures did not exceed the ROD target
cleanup level of 1 ppm established for the site.
B. Analysis of Remedial Action Performance and Restoration Timeframe
The groundwater remedial alternative stipulated in the 1989 ROD was the installation and
operation of a pump and treat system. During the development of the conceptual understanding
of the site, the effectiveness of the pump and treat system was evaluated. This evaluation
indicated that a traditional pump and treat system could mobilize contaminants vertically
downward and further contaminate groundwater. Consequently, a VER system was chosen
rather than a traditional pump and treat system. The construction and operation of the VER
system differed from the pump and treat system, as originally conceived, in that it extracts oil
and water from the site without significantly lowering the groundwater table. This would limit
the drawdown of the water table into the bedrock and therefore not allow mobilized residual oil
to enter the bedrock, which could further contaminate the bedrock groundwater.
As described in detail in the Draft Proposed Final Management of Migration Remedy (W&C,
1997d), the VER pilot study was conducted with the objective of recovering oil both in the
saturated and unsaturated zones without further contaminating the bedrock groundwater. The
operation of the VER pump and treat system (Phases I and II conducted in 1996 and 1997),
coupled with the long-term operation and pulsing of the system, resulted in the removal of 26.6
gallons of oil from within the primary migration pathway and from source areas within clay
fractures in the TWA II Area (see Table 4).
During Phase II of the VER system operation, the limitations of the aquifer were realized with
respect to oil recovery. Some of the residual oil in the immediate vicinity of the VER well was
removed, but as vacuum pressure decreased away from the well, surface tension forces and
limitations inherent with multi-phase flow inhibited the movement of residual oil to the well.
The VER system was then pulsed, to create a stress in the system, in an effort to induce product
recharge to the extraction well. Following two weeks of operations (Phase II), the system was
pulsed for another three months in an effort to try and remove as much oil as possible. During
this time, approximately 10 gallons of oil was removed only when the system was pulsed.
Following the completion of the SCRA, passive oil recovery has been conducted in bedrock
wells in the TWA II Area. The amount of oil recovered passively between December 1997 and
August 2001 was 7.1 gallons. In the past, the VER system had successfully removed oil from
the till/bedrock interface; therefore, in August 2001 VER Phase III system operation was
initiated to address the removal of oil in both the bedrock and overburden soils. A total of 19.8
gallons were recovered during this VER operation compared to 26.6 gallons collected during
Phase I and Phase II VER operation. Following the VER Phase III, between November 2001
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and March 2002, 1.9 gallons of oil were recovered passively from the wells. Most of this oil
(1.7 gallons) was recovered in OW-302B, and appears to be directly related to oil induced to the
well by the VER. The total oil since the SCRA completion is 28.8 gallons (Phase III and the
passive recovery).
Based on the results of groundwater monitoring data and the studies completed onsite, the
groundwater and mass flux through both the bedrock and overburden flow systems appears to be
very low. Due to removal of contaminated source soils during the SCRA, and removal of
additional residual oil from the overburden and bedrock, the concentrations of VOCs in
groundwater have been reduced and are expected to continue to decrease. Concentrations of
VOCs are below MCLs and MEGs outside of the TI Zone. At MW-104B and OW-201B, just
inside the proposed TI Zone, but outside of the TWA II Area, VOCs slightly exceed MEGs.
Based on the observed trends of decreasing VOC concentrations in these wells, it is estimated
that VOC concentrations will be below MCLs and MEGs at wells outside the TWA II Area
within the next 5 to 10 years.
As noted in the discussion of oil movement within the subsurface, recovery and or treatment of
residual oil will be difficult. It is believed that it could take hundreds of years to remove the
residual oil and meet drinking water standards for PCBs and VOCs within the TWA II Area. As
previously stated, residual oil, the primary source of PCBs and VOCs, is trapped in fractures in
clay and bedrock within the TWA II Area. The quantity of residual oil remaining is unknown
and due to surface tension and other forces holding this residual oil in equilibrium, there is little
migration under normal conditions.
Even though the VER system has removed a moderate amount of residual oil, and may continue
to remove oil, the difficulty of inducing oil movement within the clay desiccation cracks and the
bedrock fractures makes it unlikely that the residual oil can be completely removed. Therefore,
there will always be residual oil available to water infiltrating into the TWA II Area. Because
the TWA II Area is at the top of the ridge, there is little groundwater flow through this area.
Most of the groundwater flow through the TWA II Area is from the infiltration of rainwater and
snowmelt. The infiltrating water will dissolve PCBs and VOCs to their respective solubilities,
continuing to add dissolved source to the groundwater within the TWA II Area.
In order to estimate the dissolution time of PCBs within the oil, a simple solubility calculation
was done. This calculation did not incorporate the dissolution of the oil itself. It is believed that
the oil will remain essentially unchanged and the PCBs will dissolve out of the oil. Assuming
that there is approximately 100 gallons of oil left as residual, with an average concentration of
3000 ppb and a solubility of 2.7 ppb (USEPA, 1990) and assuming approximately 2.5 gpm
groundwater flow through the system at a dissolution concentration of 20% of solubility, the
time to dissolve the PCB's would be 372 years. Given dissolution of 10% of solubility, time to
dissolve would be 744 years. As noted above, since the quantity of residual oil remaining in the
subsurface is unknown, one hundred gallons was chosen as a reference point.
The technical impracticability evaluation identified and screened eighteen technologies to assess
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their ability to restore the groundwater to drinking water quality within a reasonable timeframe.
These technologies included insitu application of oxidizers, alternate groundwater containment
approaches, as well as excavation of all overburden soil. The evaluation concluded that none of
these technologies would achieve the cleanup goals within a reasonable timeframe.
In summary:
The majority of PCBs were removed during the SCRA in 1996 and 1997; residual oil
containing PCBs and VOCs remains trapped in bedrock fractures and desiccation fractures in
the clay;
Site investigations show that there is little movement of residual oil containing PCBs and
VOCs from the TWA II Area;
The VER system has had moderate success removing oil from the bedrock and overburden;
A Restrictive Covenant has been signed by CMP and Maine DEP that prohibits use of the
groundwater beneath the site. Public water is available on Route 17 to the south and Cony
Road to the west. The nearest known residential well is approximately a half mile to the
east, situated on a hill about two hundred feet above the Riggs Brook discharge area. This
well intercepts flow moving west toward Riggs Brook. Therefore, there is no current
drinking water exposure;
Based on the observed trends of decreasing VOC concentrations in groundwater since the
completion of the SCRA, it is estimated that VOC concentrations at wells outside of the
TWA II Area will be below MCLs and MEGs within the next 5 to 10 years; and
Due to the difficulty of removing residual oil, it is believed that it could require hundreds of
years to remove residual oil and meet drinking water standards for PCBs and VOCs within
the TWA II Area.
5. Cost Estimates
The cost estimate of the amended remedy is described in Section X below.
More detailed information regarding the technical impracticability of restoration of the
overburden and bedrock groundwater can be found in the Final Technical Impracticability
Evaluation Report. (W&C, June 2002)
IX. COMPARATIVE ANALYSIS OF THE ORIGINAL REMEDY AND
OU-2 ALTERNATIVES
Section 121(b)(l) of CERCLA presents several factors that EPA is required to consider in its
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assessment of alternatives. Building upon these specific statutory mandates, the NCP articulates
nine evaluation criteria to be used in assessing remedial alternatives. These criteria are as
follows:
Threshold Criteria
In accordance with the NCP, two threshold criteria must be met in order for the alternative to be
eligible for selection:
1. Overall protection of human health and the environment addresses whether or not a
remedy provides adequate protection, and describes how risks posed through each
exposure pathway are eliminated, reduced or controlled through treatment, engineering
controls or institutional controls.
2. Compliance with applicable or relevant and appropriate requirements (ARARs)
addresses whether or not a remedy will meet all of the ARARs of promulgated state and
federal environmental and facility-siting requirements, and if not, provides the grounds
for invoking a CERCLA waiver(s) for those requirements.
Primary Balancing Criteria
The following five criteria are used to compare and evaluate those alternatives which fulfill the
two threshold criteria.
3. Long-term effectiveness and permanence assesses alternatives for the long-term
effectiveness and permanence they afford, along with the degree of certainty that they
will be successful.
4. Reduction of toxicity, mobility or volume through treatment addresses the degree to
which alternatives employ treatment to reduce toxicity, mobility or volume, and how
treatment is used to address the principle threats posed by the site.
5. Short term effectiveness addresses the period of time needed to achieve protection and
any adverse impacts on human health and the environment that may be posed during the
construction and implementation of the alternative until cleanup goals are achieved.
6. Implementability addresses the technical and administrative feasibility of an alternative,
including the availability of materials and services needed to implement a particular
option.
7. Cost includes estimated capital as well as operation and maintenance costs, on a net
present-worth basis.
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Modifying Criteria
The two modifying criteria discussed below are used in the final evaluation of remedial
alternatives generally after EPA has received public comment on the RI/FS and Proposed Plan.
8. State acceptance addresses the State's position and key concerns related to the preferred
alternative and other alternatives, and the State's comments on ARARs or the proposed
use of waivers.
9. Community acceptance addresses the public's general response to the alternatives
described in the feasibility study and Proposed Plan.
The following is a comparison of the 1989 ROD remedy and the alternatives evaluated for this
ROD amendment, contrasting each remedy's components with respect to the nine evaluation
criteria.
1989 Remedy
The 1989 ROD selected a comprehensive approach to the contamination. The source control
actions included the cleaning, demolition, and off-site disposal of the barn situated along Route
17, removal and off-site disposal of the standing water in the two lagoons, and the excavation
and treatment by solvent extraction of the soils and sediments contaminated with PCBs, cPAHs,
and lead. Management of migration actions included the pumping, treatment, and disposal of
the contaminated groundwater from the soil and bedrock, and sampling of sediment and fish in
Riggs Brook for ten years.
Alternative 1: Institutional Controls, Long-Term Monitoring, and Passive Oil Recovery
In this alternative, EPA recognizes that the groundwater beneath a portion of the site (TI zone,
see Figure 3) will not be of drinking water quality for an extended period of time, potentially
more than a hundred years for reasons stated above in Section VIII. While the area of Augusta
where the site is located has not seen rapid growth during the time the F. O'Connor Company
operated or since its closing, the area can reasonably be expected to experience some growth
during the time period needed to reach the drinking water quality. Therefore, established and
formal controls are needed to prevent use of the groundwater on the site and to prevent the
contamination from spreading by stressing the aquifer beneath the site. CMP and Maine DEP
have entered into a Restrictive Covenant that prohibits use of the groundwater without prior
approval from Maine DEP. This Restrictive Covenant will remain in place until terminated by
Maine DEP. Should, however, EPA find that this covenant is no longer protective, effective, or it
interferes with the performance of the remedy, additional institutional controls will be placed on
the property.
Operation and maintenance activities will ensure that the institutional controls remain in place
and are effective for their stated purpose and that the Site is managed properly to maintain the
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protective layer of clean soil above those soils with low levels of PCBs.
Long-term monitoring of the groundwater will allow EPA and Maine DEP to track the residual
oil and dissolved PCBs and VOCs within the TI zone and outside of it. This data will allow the
agencies to evaluate whether the concentrations are continuing to decrease, whether the
contamination is moving beyond its current limit, and whether there is a change in
concentrations discharging into Riggs Brook wetlands. In the event that the monitoring data
indicate an increase in PCB or VOC levels, response actions will be evaluated, and as
appropriate, implemented as part of this amended ROD.
In addition to these components, Alternative 1 would include passive oil recovery where
absorbent materials would periodically be used to recover free oil which has drained under
normal conditions into the TWA II wells. This would continue until free oil was no longer
observed in the wells. The absorbent materials would be disposed of at a licensed TSD facility.
The estimated period of operation for this alternative is in excess of one hundred years. The
estimated net present worth for this alternative is $622,000. (Costs were developed for thirty
years per EPA guidance; however, EPA expects it will take considerably longer to reach
drinking water quality.)
Alternative 2: Institutional Controls, Long-Term Monitoring, Active and Passive Oil
Recovery
This alternative is EPA's selected alternative. It adds active recovery of residual oil to the
components included in Alternative 1. On an annual basis, a vacuum would be applied to wells
within TWA II to draw the residual oil and VOCs from the soil and bedrock. EPA is proposing
the annual application to coincide with normal low groundwater levels as that has been the time
when the amount of oil in the wells has been the greatest. Each application would continue as
long as it was practical to remove the oil (the criteria for this is further discussed in Section
X.2.). Past application suggests that each application would last about four to six weeks. The
annual application, from year to year, would continue as long as it was practical. Passive oil
recovery would be implemented between the active pumping efforts. The recovered oil and the
absorbent materials would be disposed of at a licensed TSD facility.
The estimated period of operation for this alternative is in excess of one hundred years. The
estimated period of operation for the active oil recovery is five to ten years. The estimated net
present worth for this alternative is $1,055,000. (As with Alternative 1, costs were developed
for thirty years per EPA guidance)
EPA developed these alternatives based on information contained in the 2002 Technical
Impracticability Evaluation submitted by CMP, which in turn followed discussions with EPA
and Maine DEP regarding site conditions.
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Comparison of the Original Remedy for Groundwater and the OU-2 Alternatives to the
Nine Criteria
1. Overall Protection of Human Health and the Environment
This criterion considers whether the remedy, as a whole, will protect human health and the
environment. This includes an assessment of how public health and environmental risks are
properly eliminated, reduced, or controlled through treatment, engineering controls, or
institutional controls.
The original remedy included pump and treat technology as the method to achieve groundwater
restoration throughout the Site. While this technology was to be implemented, short-term
institutional controls were to be set in place to prevent exposure to the contaminated
groundwater. This selection was consistent with the belief at the time that this technology could
effectively restore contaminated groundwater. In 2002, EPA concluded that restoration was not
feasible. Therefore, without achieving restoration within a reasonable time frame or having a
long-term means to prevent exposure to the contaminated groundwater, the original remedy is no
longer protective of human health and the environment in the long-term.
Alternatives 1 and 2 recognize that for a portion of the site, it is technically impracticable to
restore the groundwater to drinking water quality, and therefore, to prevent exposure to the
contaminated groundwater for an extended period of time, a long-term institutional control is a
component of both alternatives. In addition, both alternatives include long-term monitoring of
groundwater to demonstrate that the contamination is not expanding and that natural processes
will continue to decrease the contaminant concentrations. Alternative 2 provides greater overall
protection by actively removing separate phase oil from the overburden soil and bedrock and
thus more quickly reduces the toxicity. Thereby, with the institutional control provided by the
Restrictive Covenant, this component ensures the protectiveness of the remedy.
The protection of human health and the environment is the most important criterion. The
Restrictive Covenant protects human health as it prevents human exposure to contaminated
groundwater. The environment is protected through the soil removal and recovery of the free oil
(by removing the source of contamination, the amount of residual contamination available to
aquatic and terrestrial receptors is expected to continue to decrease). Long-term monitoring will
allow EPA and Maine DEP to know whether the remedy is appropriate. Both alternatives EPA
evaluated rely on the Restrictive Covenant and long-term monitoring.
2. Compliance with Applicable and Relevant and Appropriate Requirements
This criterion addresses whether or not a remedy complies with all promulgated state and federal
environmental and facility siting requirements that apply or are relevant and appropriate to the
conditions and remedy at a specific site. If an ARAR cannot be met, the analysis of a remedy
must provide the grounds for invoking a statutory waiver.
33
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When the original remedy was selected in the 1989 ROD, it was believed that the remedy would
attain all identified federal and state ARARs.
Both alternatives include a TI waiver of drinking water standards for the area identified as the TI
zone (See Figure 3) and would comply with all other identified federal and state regulations as
well as drinking water standards outside of the TI zone. PCB and VOC levels outside the TI
zone are currently below EPA's standards but at times are slightly above Maine's standards. As
the concentrations have decreased following the 1997 soil removal action, and active and passive
oil recovery will continue, it is anticipated that the Maine standard will be consistently met
outside the TI zone in five to ten years. EPA anticipates that active recovery of the oil under
Alternative 2 will more quickly lower the PCB and VOC concentrations in the TI zone than just
the passive recovery provided in Alternative 1. However, it is likely that at the conclusion of
active recovery the dissolved concentrations within the TI zone will still be above the drinking
water standards. Because the ROD Amendment waives federal and state drinking water
standards for a portion of the site, EPA sought comment from the public regarding this during
the public comment period.
3. Long-term Effectiveness and Permanence
This criterion refers to the ability of a remedy to maintain reliable protection of human health
and the environment over time once the remedial action is complete.
The original remedy would have provided long-term effectiveness and permanence once site
groundwater had been restored to drinking water quality. However, since it was demonstrated
that the pump and treat technology could not restore the groundwater within a reasonable
timeframe, there were concerns that the Restrictive Covenant alone would not have the ability to
provide and maintain reliable long-term effectiveness. For this reason, additional institutional
controls could be used in the future to ensure long-term effectiveness and permanence under
both alternatives evaluated by EPA.
The long-term protection criterion would be met by both alternatives EPA evaluated. If the
Restrictive Covenant is not effective or protective in the future, additional institutional controls
will be required by EPA. The groundwater monitoring will continue under both alternatives as
long as the PCB and VOC concentrations remain above drinking water quality. Additionally,
operation and maintenance activities will continue to ensure the effectiveness and protectiveness
of the institutional controls.
4. Reduction of Toxicity. Mobility, and Volume through Treatment
This criterion contains three measures of the overall performance of a remedy. The 1986
amendments to the Superfund statute emphasize that, whenever possible, EPA should select a
remedy that uses a treatment process to permanently reduce the level of toxicity of contaminants
at the site, inhibit or eliminate the spread of contaminants away from the source of
contamination, and reduce the volume, or amount of contamination at the site.
34
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The original remedy for the groundwater operable unit used a proven technology, pump and
treat, to reduce toxicity, mobility, and volume in the overburden and bedrock groundwater.
However, as noted elsewhere, the presence of separate phase oil with PCBs and VOCs in both
the fractures in the overburden clay soil and in the bedrock, and the limited recharge of
groundwater in the contaminated source area greatly limited the effectiveness of pump and treat
technology in reducing toxicity, mobility, and volume.
Both alternatives would include the removal of residual oil. Alternative 1 would remove the oil
as it moves under natural conditions into monitoring wells, whereas Alternative 2 would also
employ a pumping system to increase the rate of the recovery. The recovered oil is transported
offsite to a licensed TSD facility. Using active recovery under Alternative 2, the volume of the
residual oil will be reduced much more quickly then relying on natural conditions as proposed in
Alternative 1. In turn, this will further decrease its mobility through the subsurface. Therefore
Alternative 2 provides the greatest reduction of toxicity, mobility, and the volume of
contaminants through treatment.
5. Short-term Effectiveness
This criterion refers to the likelihood of adverse impacts on human health or the environment
that may be posed during the construction and implementation of a remedy.
EPA does not believe that the original remedy for groundwater posed significant short-term
effectiveness concerns. The potential exposure of site workers and area residents to
contaminated air emissions during construction of the extraction and re-injection wells was
minimized by using standard safety plans that included air emissions controls and a network of
ambient air monitors to assess potential releases to the air during drilling operations. The
implementation of the pump and treat technology likewise did not pose significant short-term
effectiveness concerns.
Both alternatives meet the short-term effectiveness criterion in similar ways. The
implementation of institutional controls reduces site risks from groundwater quickly. The only
remedial actions are the long-term monitoring and the oil recovery, both of which have been
ongoing for years, and the sampling crews follow established health and safety procedures. As
stated above, the recovered oil and absorbent materials are currently transported to a licensed
TSD facility and will continue to be shipped offsite safely and in accordance with all legal
requirements.
6. Implementability
This criterion refers to the technical and administrative feasibility of a remedy, including the
availability of materials and services needed to implement the remedy.
The original groundwater remedy was implementable as demonstrated by the installation of
recovery and re-injection wells that were operated successfully during the pilot pumping studies.
35
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Both alternatives evaluated in this ROD Amendment for OU-2 can be easily implemented. The
materials and equipment needed for maintenance of the site, long-term monitoring, and oil
recovery are all readily available. The VER system is already installed and has been operated in
three separate trials spanning several months. The Restrictive Covenant is currently in place. If
additional institutional controls are needed, they also can be readily implemented.
7. Cost
This criterion includes the net present worth estimates for capital (up-front) and operation and
maintenance costs of implementing each alternative evaluated for OU-2. The costs described
below do not include previous site-wide costs which were substantial. The cost estimates only
reflect those costs that would be incurred henceforth to implement the alternatives evaluated.
The estimated total present worth costs associated with the management of migration component
in the 1989 ROD was $679,000 with operation and maintenance costs for thirty years
comprising $631,000 of the total.
In evaluating the alternatives for costs, EPA notes that the net present worth has been calculated
for thirty years, following EPA guidance, whereas it is the expectation of all parties that the
cleanup activities will last considerably longer. The net present worth of Alternatives 1 and 2
are $622,000 and $1,055,000, respectively.
8. State Acceptance
This criterion addresses whether, based on its review of the data derived from the site and the
Proposed Plan, the State concurs with, opposes, or has no comment on the amendment that EPA
has selected for the site.
Maine DEP has reviewed the June 2002 Proposed Plan to amend the 1989 Cleanup Plan and a
draft of this amendment. The Maine DEP concurs with the remedy change with certain
conditions. These conditions have been addressed. The Maine DEP has provided a letter of
concurrence which is provided in Appendix C.
9. Community Acceptance
This criterion addresses whether the public concurs with EPA's proposed Amendment.
Compliance with this criterion is based on the comments received at the public meeting and
public hearing.
Based on the public information and public hearing meetings and comments received during the
public comment period, it appears that the proposed amendment has community support.
X. THE SELECTED REMEDY FOR OU-2
36
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EPA has selected the remedy described below as the best balance between the nine criteria. The
selected remedy relies on institutional controls, active oil recovery, and long-term monitoring of
overburden and bedrock groundwater. This remedy was selected within the context of the
determination by EPA that it is technically impracticable to restore the groundwater for a limited
portion of the Site within a reasonable timeframe.
For the amended cleanup plan for OU-2, EPA has selected a remedy which ensures
protectiveness of human health and the environment, attains all federal and state regulations with
the exception of waiving drinking water standards for a portion of the site, provides long-term
and short-term effectiveness, is implementable, and reduces toxicity, volume, and mobility
through treatment. The amended cleanup plan for OU-2 includes:
1. Institutional controls to prevent exposure to the contaminated groundwater
In 1994, CMP and Maine DEP signed a Restrictive Covenant on a portion of the property
which prevents certain activities without written approval from Maine DEP (see Figure 4).
The Covenant requires CMP to maintain the property to ensure that the remedy remains
protective. The Covenant runs with the land and is binding on all future owners. The
Restrictive Covenant was recorded at the Kennebec County Registry of Deeds on September
13, 2002. If the Covenant is released prior to the completion of the remedy, or if EPA finds
that it is not effective and protective, EPA will require other institutional controls be put in
place on the site.
An operation and maintenance plan will be implemented to ensure that the institutional
controls are being followed, that they are effective and protective, and that the Site is
managed properly. The O&M plan will include a schedule for monitoring the soil cover,
resurveying of the designated area, and periodic sampling and analysis to ensure the integrity
of the soil cover over the designated area. This sampling will coincide with the five-year
reviews and will consist of a limited number of soil samples collected from about 6-8 inches
below the ground surface and analyzed for PCBs.
2. A combination of active and passive removal of the oil and associated PCBs
A vacuum-enhanced pumping system will be used annually to remove oil from the
groundwater. This system will be operated on an annual basis in late summer- early fall until
it is determined to be no longer effective. Criteria to be used to make this determination
include the following:
apply the VER to four wells (101, 202B, 310B, and 302B) in the TWA II area at
least once every year for the next five years (2007). The necessity and conditions
for continuation of the VER would be addressed during the next five 5-year
review, scheduled for September 2007, and each subsequent 5-year review
period.
After application of the VER to a well, recovery of oil will be observed over a
37
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period of up to one week.
If a "significant " amount of oil is recovered from the well, the VER will be
reapplied to the well. A "significant" amount of oil will be defined as an increase
in the amount of oil recovered relative to the amount of oil recovered through
passive means. Basically this means that if the VER is effectively increasing the
amount of oil being recovered from a well, it will continue on that well.
The operation of the VER will continue for a period of up to two months if significant
amounts of oil are recovered. After this time weather constraints and rising groundwater
elevations are expected to limit the effectiveness of the VER.
It is expected that the VER will be operated for the next five years and this determination
regarding the continued operation of the VER as part of this ROD Amendment will be made in
conjunction with the next five-year review scheduled for summer 2007.
This component of the remedy requires placement of absorbent materials in monitoring wells
after the conclusion of the pumping to absorb any remaining residual oil. The use of absorbent
materials will continue until as long as it is practical, i.e, as long as oil is visibly detectable.
Between active operation of the VER, the wells are currently monitored on a monthly basis. It is
anticipated that this frequency will be reduced to quarterly in the future. All recovered oil and
used absorbent material will be disposed of at a licensed TSD facility.
3. Monitoring the groundwater to demonstrate that the contamination is not expanding and that
natural processes will continue to decrease the contaminant concentrations.
This component of the remedy requires implementation of a long-term groundwater
monitoring program to track dissolved PCB and VOCs. This program will be a modification
of the current monitoring program.
It will also require tracking the progress of attenuation by monitoring dissolved contaminant
levels beyond the area where the oil is present in the groundwater. This monitoring data will
be used to verify that the dissolved contaminant concentrations are decreasing.
Finally this component of the remedy will include contingencies should the groundwater
monitoring indicate the contamination is moving beyond its current limits. Contingencies
may include increased sampling frequency, implementation of additional sampling locations,
including any residential wells installed on adjacent properties, reevaluation of the
conceptual model, and increased operation of the VER.
4. Evaluating the cleanup approach to confirm that it is protective of human health and the
environment
38
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As long as contamination remains which prevents unrestricted use of the site, the Superfund
law requires reviews every five years to evaluate the effectiveness of the implemented
cleanup plan. As part of each five year review, EPA will review the site conditions to
determine if the cleanup action remains protective, consider new technologies, and refine the
time estimates necessary to reach the groundwater standards.
In addition to these components for OU-2, monitoring Riggs Brook for OU-3 will continue as
specified in the 1989 ROD, to track changes in PCB concentrations and to demonstrate no
unacceptable impact on sediment quality or aquatic or terrestrial organisms.
XL STATUTORY DETERMINATIONS
The remedial action selected herein for implementation for O'Connor OU-2 is consistent with
CERCLA and, to the extent practicable, the NCP.
A. The Selected Remedy is Protective of Human Health and the Environment
The selected remedy will be protective of human health and the environment. Exposure to
contaminated groundwater will be prevented through the Restrictive Covenant or other
institutional controls. This Covenant includes the following:
any use of the groundwater beneath the site is prohibited without the written approval of
Maine DEP;
any activity which might disrupt remedial or monitoring measures is prohibited without the
written approval of Maine DEP; and
CMP or any subsequent owner shall maintain the site in a condition adequate to ensure the
continued compliance with all applicable standards and to ensure the ongoing adequacy of
the remediation.
If other institutional controls are required, they will ensure the protectiveness of the remedy.
Active recovery of PCB-oil will decrease the mass and volume of the contaminants of concern as
well as reduce its mobility. Long-term monitoring of the groundwater will allow EPA to track
the decreasing concentrations present in the overburden soils and bedrock aquifer. There are no
significant short-term risks to human health or the environment during implementation of the
selected remedy. The potential exposure of site workers and area residents during the annual oil
recovery will be monitored to assess potential releases to the air during cleanup operations. As
active oil recovery has been implemented at the site since 1996, its continuation as part of the
ROD Amendment remedy is not anticipated to pose any significant risks to site workers or area
residents.
39
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B. The Selected Remedy Attains or Appropriately Waives ARARs
ARARs for the site were identified during the development of the 1989 ROD. As a part of the
TI Evaluation process, a review of current ARARs was conducted and is summarized below.
Section 300.430 (e) of the National Contingency Plan (NCP) requires that on-site remedial
actions at CERCLA sites must meet ARARs under federal or state environmental or facility
siting laws unless there are grounds for invoking a waiver. A waiver is required if ARARs
cannot be achieved. Other federal and state advisories, criteria, or guidance, as appropriate (to
be considered - TBCs), should be considered in formulating the remedial action.
ARARs are promulgated, enforceable federal and state environmental or public health
requirements. There are two categories of requirements: "applicable" and "relevant and
appropriate". CERCLA does not allow a regulation to be considered as both "applicable" and
"relevant and appropriate". These categories are defined below:
Applicable Requirements - Section 300.5 of the NCP defines applicable requirements as "those
cleanup standards, standards of control, and other substantive environmental protection
requirements, criteria, or limitations promulgated under Federal or State law that specifically
address a hazardous substance, pollutant, contaminant, remedial action, location, or other
circumstance at a CERCLA site".
Relevant and Appropriate Requirements - Section 300.5 of the NCP defines relevant and
appropriate requirements as "those cleanup standards, standards of control, and other substantive
environmental protection requirements, criteria, or limitations promulgated under Federal or
State law that, while not 'applicable' to a hazardous substance, pollutant, contaminant, remedial
action, location, or other circumstance at a CERCLA site, address problems or situations
sufficiently similar to those encountered at a CERCLA site that their use is well suited to the
particular site."
To be considered (TBCs) guidelines are non-promulgated criteria, advisories, and guidance
issued by the federal or state governments. Along with ARARs, TBCs may be used to develop
interim action limits necessary to protect human health and the environment.
ARARs and TBCs are divided into three categories: chemical-specific, location-specific, and
action-specific. This section briefly summarizes the most significant chemical, location and
action specific ARARs for the remedy and identifies those for which a technical impracticability
waiver is sought.
Chemical-Specific ARARs
Chemical-Specific ARARs are usually health- or risk-based numerical values or methodologies
which, when applied to site-specific conditions, result in the determination of numerical values
that establish the acceptable amount or concentration of a chemical that may be found in, or
40
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discharged to, the ambient environment. These requirements do not consider the mixture of
chemicals. A summary of chemical specific ARARs is presented in Table 6.
The federal Maximum Contaminant Levels (MCLs) are chemical-specific ARARs that govern
the quality of drinking water provided by public water supply. MCLs are relevant and
appropriate requirements in establishing remediation goals for groundwater at the site and are
ARARs outside the TI zone.
The 1992 State of Maine Maximum Exposure Guidelines (MEGs) are chemical-specific ARARs
that are health-based guidelines intended to determine drinking water quality for private
residential wells. MEGs are relevant and appropriate requirements in establishing remediation
goals for groundwater at the site. Maine MEGs were revised in 2000, but have not been
promulgated and therefore, the 2000 Maine MEGs are TBCs.
The MCLs and MEGs for which a technical impracticability waiver will apply are noted in the
Table 3 in Section VIII above.
Location-Specific ARARs
Location-specific ARARs are restrictions placed on the concentrations of hazardous substances,
or the conduct of activities solely because they are in specific areas. The general types of
location-specific ARARs that apply to the site are briefly described below and are presented in
Table 7.
Several federal and state ARARs regulate activities that may be conducted in wetlands and
floodplains. Regulations governing endangered species at the federal and state levels would
need to be considered for any proposed on-site actions. The Maine Natural Resources Protection
Act governs activities that may occur in or adjacent to wetlands or surface water bodies. The
Maine Site Location Development Law regulates activities that may adversely affect existing
land uses, and scenic character or natural resources, and needs to be considered in the
implementation of an alternative.
No waiver of location-specific ARARs is being sought for the technical impracticability
evaluation for the Site.
Action-Specific ARARs
Action-specific ARARs are usually technology- or activity-based requirements or limitations on
actions taken with respect to hazardous wastes. These requirements are generally focused on
actions taken to remediate, handle, treat, transport, or dispose of hazardous wastes. These
action-specific requirements do not in themselves determine the remedial alternative; rather they
indicate how a selected alternative must be implemented. The general types of action-specific
ARARs that apply to the site are briefly described below and are presented in Table 8.
The Toxic Substances Control Act (TSCA) regulates the marking, storage, disposal and cleanup
41
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of spills of PCBs greater than 50 ppm PCBs. In addition, the Maine Hazardous Waste
Management Rules also regulate treatment, storage and disposal of hazardous wastes, including
PCBs. These regulations would need to be in the implementation of any alternative that includes
the removal and/or treatment of contaminated groundwater and residual oil.
No waiver for action-specific ARARs is being sought for the technical impracticability
evaluation for the Site.
C. The Selected Remedial Action is Cost-Effective
The selected remedy is cost-effective since it provides overall effectiveness proportional to its
cost.
The projected net worth costs over thirty years for the two amendment alternatives evaluated
were $0.622 million for Alternative 1 and $1.055 million for Alternative 2. The selected remedy
Alternative 2 actively removes contamination through treatment from the groundwater whereas
Alternative 1 does not include active removal. Additionally, EPA believes the actual cost
difference for the two alternatives is not as great at it appears. These costs have been calculated
based on thirty years, yet it is anticipated that the long-term monitoring for OU-2 will continue
considerably longer. However, by actively removing the oil on an annual basis as long as it is
practical, EPA expects this will shorten the time period for groundwater restoration and thereby
require less long-term monitoring compared to Alternative 1.
D. The Selected Remedy Does Utilize Permanent Solutions and Alternative Treatment or
Resource Recovery Technologies to the Maximum Extent Practicable
The selected remedy provides a permanent solution and alternative treatment or resource
recovery technologies to the maximum extent practicable for the separate phase oil through
active oil recovery. Through institutional controls, the groundwater is isolated from human use
and thus prevents exposure. Extrapolations of groundwater monitoring data downgradient of the
TI zone indicate that the groundwater beyond the TI zone will attain the cleanup standards
within the next ten years.
Through the active recovery of oil on an annual basis, the selected remedy reduces the mass of
contamination more quickly than natural attenuation processes. Following the completed SCRA,
the active oil recovery seeks to permanently further reduce the source of contamination for the
downgradient groundwater and Riggs Brook.
E. The Selected Remedy Does Satisfy the Preference for Treatment as a Principle Element
The selected remedy does use treatment of the PCB oil-contaminated groundwater as a principle
element of the remedy. The recovered oil is transported offsite to a licensed TSD facility.
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F. Five Year Reviews
Because this amendment would result in contaminants remaining onsite, EPA will review the
site at least once every five years after the initiation of the remedial action at the site to assure
that the remedial action continues to be protective of human health and the environment. This
review will be consistent with the CERCLA §121(c) applicable for five-year site reviews in
effect at the time of the review. The first five-year review for the site was triggered by the start
of the source control remedial action and was completed in September 2002.
XII. DOCUMENTATION OF NO SIGNIFICANT CHANGES
The Proposed Plan to amend the 1989 ROD, as it pertained to the MOM, was released for public
comment in June 2002. The proposed change calls for attaining protectiveness of human health
through institutional controls and long-term monitoring rather than attaining protectiveness of
human health through restoration of the site groundwater through active remedial action. The
amended cleanup plan does include active recovery of the PCB laden-oil, thereby providing
treatment as a component of the remedy.
EPA determined that, based on comments received during the public comment period which
concluded on July 19, 2002, no significant change is needed to the proposed amended cleanup
plan. EPA has prepared a responsiveness summary to address the comments received during
the public comment period. The responsiveness summary is attached as Appendix A.
XIII. STATE ROLE
The Maine Department of Environmental Protection has reviewed the remedy change and
concurs with the selected remedy described in Section X of this Amendment. A copy of the
State concurrence letter is attached as Appendix C.
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September 2002 ROD Amendment
F. O'Connor Superfund Site
Table 1: Comparison between 1989 ROD and 2002 ROD Amendment
1989 ROD - Groundwater components
#1: temporary institutional controls. This
would prevent exposure to site groundwater
while remediation was underway.
#2: pump-and-treat system. The appropriate
sizing of the system, including the number of
extraction wells, pumping rate, treatment
components such as granular activated carbon,
sand filters, air stripper, and number of recharge
wells was to be determined during the remedial
design phase.
#3: a network of monitoring wells. The wells
used in the RI would be assessed and augmented
with additional wells in both overburden soil
and bedrock.
#4: Riggs Brook sediment and biota monitoring.
Brook sediments were to be monitored yearly for
ten years to assess PCB concentrations. Biota
sampling was to occur five years after initiation
of the monitoring.
#5: five-year reviews. The progress toward
restoration of the site groundwater and the target
clean up goal for the sediment were to be
assessed during each five-year review.
2002 ROD Amendment for OU-2
#1 permanent institutional controls. With the
1994 BSD, CMP and Maine DEP signed a
restrictive covenant which prevented certain
activities at the site without written approval of
Maine DEP.
#2: annual application of the VER system. The
VER has been operated three times post-ROD,
recovering PCB-laden oil from the overburden
and bedrock. The VER will be applied annually
in TWA II area wells to recover as much oil as
is practical.
#3 monthly monitoring of oil levels in TWA II
wells and removal using absorbent materials.
Between the annual operations of the VER, the
TWA II will be monitored for separate phase
oil. Detected oil will be removed using
absorbent material. It is expected that
monitoring frequency will decrease as the
amount of oil draining into the wells decreases.
#4: long-term monitoring. It will be performed
to track contaminant levels in the TI zone and
outside it.
#5: Riggs Brook sediment and biota monitoring.
It will continue as OU-3, established in 1996
#6: five-year reviews. Reviews will be
conducted to ensure that the site remedy for all
three OU's remains protective.
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September 2002 ROD Amendment
F. O'Connor Superfund Site
Table 2: PCB Results - TWA II
PCB Results (ug/L) - TWA II
Sampling Date
3/98
6/98
9/98
12/98
3/99
6/99
9/99
3/00
9/00
4/01
9/01
ow-
202B
ND
ND
NS
ND
0.79
NS
NS
NS
NS
0.35
NS
ROD Cleanup Standard
OW- OW-
204B 301B
ND
ND
0.64
Jl.O
ND
1.17
NS
NS
0.62
ND
NS
5.6
1.2
1.7
7.1
3.1
2.9
NS
NS
8.6
3.5
NS
0.5 ug/L
OW-
302B
2.5
32
1,500
8,900
930
710
NS
NS
8.6
44
NS
RW-101
2.3
1.5
NS
NS
2.32
NS
NS
NS
NS
0.12
NS
Number of
Exceedances
3
3
5
4
4
5
5
5
5
2
5
ND - non detected above PQLs
NS - not sampled due to presence of oil in well (considered an exceedance)
J - estimate due to the percent difference of continuing calibration greater than 15%.
Bold - ROD exceedance
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September 2002 ROD Amendment
F. O'Connor Superfund Site
Table 3: Chemical-Specific ARARs for TI Waiver
Contaminant
Of Concern
Benzene
Chlorobenzene
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1,4- Dichlorobenzene
1,2,3-
Trichlorobenzene
1,2,4-
Trichlorobenzene
1,3,5-
Trichlorobenzene
PCBs1
2001 Maximum
Groundwater
Concentration
(ug/L) and Location
8 - OW-302B
240 - OW-302B
210 - OW-302B
160 - OW-302B
720 - OW-302B
98 -OW-302B
770 - OW-302B
not analyzed for
44 . QW-302B
MCL
(ug/L)
5
100
600
NS
75
NS
70
NS
0.5
1992
MEG
(ug/L)
5
47
85
85
27
NS
70
40
0.05
1989 ROD Target
Cleanup Levels
(ug/L)
5
no ROD standard
no ROD standard
no ROD standard
27
no ROD standard
no ROD standard
no ROD standard
0.5
1 detection limit varies with location and are generally greater than the 1992 MEG.
NS - no standard
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September 2002 ROD Amendment
F. O'Connor Superfund Site
Table 4: Gallons of Oil Recovered From TWA II Area Wells
Period
Pump Test - 1992-1994
VER
VER Phases I & 1996-1997
II
Source Control 1997
Passive 1997-2001
Collection
VER Phase III 2001
Post VER Phase 2001-2002
III
Total
OW-
202B
15.8
0.0
0.0
2.1
1.9
0.1
19.9
ow-
204B
0.0
0.0
0.0
0.1
0.0
0.0
0.1
OW-
301B
8.3
0.0
0.0
0.2
4.6
0.0
13.1
OW-302B RW- I! Total 1
101 1 1
5.7
0.0 26.6
0.0 NA
2.3 2.4
10.1 3.2
1.7 0.1
19.8 32.3
29.8
26.6
0.0
7.1
19.8
1.9
85.2
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September 2002 ROD Amendment
F. O'Connor Superfund Site
Table 5: Summary of Groundwater Monitoring Results Modified Method 680
Analytes
Total Mono CB
Total DiCB
Total TriCB
Total TetraCB
Total PentaCB
Total HextaCB
Total HeptaCB
Total OctaCB
Total NonaCB
DecaCB (#209)
Total PCB
Total PCB &
EMPC
MW-
106A
(HS/L)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
N/A
N/A
MW-106B
(ug/L)
0.004
0.01
0.01
0.02
ND
ND
ND
ND
ND
ND
0.05
0.05
MW-503
Gig/L)
0.004
0.03
0.02
ND
ND
ND
ND
ND
ND
ND
0.06
0.09
MW-508B
(ug/L)
0.008
0.01
ND
ND
ND
ND
ND
ND
ND
ND
0.02
0.02
MW-104B
(ug/L)
EMPC*
0.04
ND
ND
ND
ND
ND
ND
ND
ND
0.04
0.07
OW-201B
(ug/L)
0
0.05
ND
ND
ND
ND
ND
ND
ND
ND
0.06
0.07
Notes: EMPC - Estimated Maximum Possible Concentration
* - EMPC=0.03
-------
Table 6: Identification of Chemical-Specific ARARs
REQUIREMENT
REQUIREMENT SYNOPSIS
GROUNDWATER
Federal Regulatory Requirements
SDWA - Section 1412 -MCLs (40 CFR
141.11-141.6)
SDWA- Section 1412 -MCLGs (40 CFR
141.50-141.51)
CWA - Section 304(a)
AWQC
USEPA Risk Reference Doses (RfDs)
USEPA Carcinogen Assessment Group
Carcinogenic Potency Factors (CPFs)
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
To be considered
To be considered
MCLs have been promulgated for several common organic and inorganic
contaminants. These levels regulate the concentration of contaminants in public
drinking water supplies, but may also be considered relevant and appropriate for
groundwater aquifers used for drinking water.
MCLGs are health-based criteria established for a number of organic and
inorganic contaminants as water quality goals for drinking water supplies . These
goals may also be considered relevant and appropriate for groundwater aquifers
used for drinking water.
Federal AWQC include (1) health-based criteria developed for 95 carcinogenic
and noncarcinogenic compounds and (2) other water quality parameters
protective offish and aquatic life. AWQC for the protection of human health
provide levels for exposure from drinking water and consuming aquatic
organisms, and from consuming fish alone. Remedial actions involving
contaminated surface water or groundwater must consider the uses of the water
and the circumstances of the release or threatened release; this determines
whether AWQC are relevant and appropriate.
RfDs are considered the levels unlikely to cause significant adverse health effects
associated with a threshold mechanism of action in human exposure for a
lifetime.
Carcinogenic effects present the most up-to-date information on cancer risk
potency derived from USEPA's Carcinogen Assessment Group.
USEPA Health Advisories (HAs)
To be considered
HAs are issued as non-regulatory guidance. HA values represent the
concentration of contaminants in drinking water at which adverse health effects
would not be expected to occur. HAs are established for one-day and ten-day
exposure durations.
-------
«U.S. Environmental Protection Agency
(USEPA) Risk Reference Doses (RfDs)
To be considered
RfDs are an estimate of a daily exposure concentration that is likely to be 1
without appreciable risk of deleterious effects during a lifetime exposure. |
|| State of Maine Regulatory Requirements
1
Maine Standards for Classification of
Groundwater (38 M.R.S.A., Chapter 3,
Section 470)
Applicable
Groundwater is classified under the Maine Standards. The groundwater at the
O'Connor Site is classified as GW-A (i.e., water shall be of such quality that it
can be used for domestic purposes.
Maine's Primary Drinking Water Standards are equivalent to federal MCLs.
Maine Drinking Water Rules (10-144A
CMR Chapters 231-233)
Relevant and
Appropriate
1992
Maine Maximum Exposure Guidelines
(MEGs)
Relevant and
Appropriate
MEGs are the Bureau of Health's recommendations for concentrations of
chemical contaminants in drinking water. MEGs are health-based guidelines and
are not legally enforceable.
2000
Maine Maximum Exposure Guidelines
(MEGs)
To be considered
MEGs are the Bureau of Health's most recent recommendations for
concentrations of chemical contaminants in drinking water. MEGs are health-
based guidelines and are not legally enforceable.
-------
TABLE 7: IDENTIFICATION OF LOCATION-SPECIFIC ARARs
REQUIREMENT
REQUIREMENT SYNOPSIS
WETLANDS/FLOODPLAINS
Federal Regulatory Requirements
National Environmental Policy Act
(NEPA, 42 USC § 4341) and Wetland
Executive Order (EO 11990), 40 CFR
Part 6, Appendix A
National Historic Preservation
Act(NHPA, 16 USC 470 etsea.. 40 CFR
800)
Clean Water Act Section 404
Requirements for Dredged or Fill
Material (33 USC 1344; 40 CFR 230)
Applicable
Applicable
(if encountered)
Applicable
The Wetlands Executive Order requires federal agencies to minimize the
destruction, loss, or degradation of wetlands, and preserve and enhance natural
and beneficial values of wetlands.
CERCLA response actions are required to consider possible effects of the
response activities on any historic property included in or eligible to be included
in the National Register of Historic Places.
Under this requirement, no activity that adversely affects a wetland shall be
permitted if a practicable alternative is available.
State of Maine Regulatory Requirements
I
J
Maine Natural Resources Protection Act
(NRPA, 38 MRSA § 480) and Permit By
Rule Standards (MEDEP Regulations
Ch. 305
Applicable
This act outlines requirements and performance standards for certain activities
in, on, over, or adjacent to freshwater wetlands, streams, ponds, or brooks. The
activities must not unreasonably interfere with certain natural features, such as
natural flow or quality of any waters, nor harm significant aquatic habitat,
freshwater fisheries, or other aquatic life.
-------
Maine Endangered Species Act and
Regulations (12 MRSA Section 7751-
7756; 09-137 CMR 008)
Applicable (if
endangered species
are identified or
encountered)
The state of Maine has the authority to research, list, and protect any species that
are determined to be threatened or endangered, according to state regulations.
The ME Department of Inland Fisheries and Wildlife has developed the
following categories for the consideration of important species that not
threatened or endangered: Maine Watch List, Special Concern List, and
Indeterminate Category. The department determines habitat uses on a case-by-
case basis. The Maine lists of species may differ from the federal.
|| OTHER NATURAL RESOURCES
Federal Regulatory Requirements
Endangered Species Act (ESA, 16 USC
§§ 1531-1534)
Applicable (if
encountered)
This act requires action to avoid jeopardizing the continued existence of listed
endangered or threatened species or notification of their habitat.
State of Maine Regulatory Requirements
J
Maine Standards for Classification of
Groundwater (38 MRSA, §§ 465-C and
470)
Applicable
This law establishes the classification of the state's groundwater to protect,
conserve, and maintain groundwater resources in the interest of the health,
safety, and general welfare of the people of the state. Groundwater is classified
as GW-A, the highest groundwater classification, and is designated as a potential
water supply. This classification applicable to remedial objectives.
Maine Endangered Species Act (MESA,
38 MRSA §§ 7001, 7751-7759) and
Maine Inland Fisheries and Wildlife
Laws and Regulations (12 MRSA §
7031 etseq.)
Applicable (if
encountered)
The State of Maine has authority to research, list, and protect any species
deemed endangered or threatened. These species are listed as either endangered
or threatened in the state regulations. The Maine Department of Inland Fisheries
and Wildlife has also developed the following administrative categories for
species not considered endangered or threatened but considered important for
research and further evaluation: Maine Watch List, Special Concern List, and
Indeterminate Category. The Department determines appropriate use(s) of
various habitats on a case-by-case- basis. The Maine lists may differ from the
federal lists of endangered species.
-------
Maine Site Location and Development
Law and Regulations (38 MRS A
Sections 481 through 490; MEDEP
Regs. Ch. 371-377)
Applicable
This act and regulations govern new development, including new developments
that handle hazardous wastes and oil. Activities cannot adversely affect existing
uses, scenic character, or natural resources in the municipality or neighboring
municipality.
Maine Critical Areas Program and Maine
Natural Heritage Program
Maine Critical Areas Act (5 MRS A §§
3310-3316)
To Be considered
To Be considered
These state programs issue policies and regulations governing special habitats or
communities.
This non-regulatory legislation allows Maine agencies such as the Critical Areas
Program and the Natural Heritage Areas Program to identify, research, and
protect critical areas and endangered or threatened plants.
|| Municipal Regulatory Requirements
I
I
Mandatory Shoreland Zoning (38 MRSA
§§ 435-449)
Town Shoreland Zoning Ordinances and
State Minimum Guidelines (38 MRSA
§§ 1801-1803, 1841-1843-A, 1901-
1905, 2013) and City of Augusta
Comprehensive Plan/Shoreland Zoning
Plan
To Be considered
These minimum guidelines and town ordinances apply to activities proposed
within 250 feet of a high-water mark of a stream or other body of water.
-------
«U.S. Environmental Protection Agency
(USEPA) Risk Reference Doses (RfDs)
To be considered
RfDs are an estimate of a daily exposure concentration that is likely to be 1
without appreciable risk of deleterious effects during a lifetime exposure. |
|| State of Maine Regulatory Requirements
1
Maine Standards for Classification of
Groundwater (38 M.R.S.A., Chapter 3,
Section 470)
Applicable
Groundwater is classified under the Maine Standards. The groundwater at the
O'Connor Site is classified as GW-A (i.e., water shall be of such quality that it
can be used for domestic purposes.
Maine's Primary Drinking Water Standards are equivalent to federal MCLs.
Maine Drinking Water Rules (10-144A
CMR Chapters 231-233)
Relevant and
Appropriate
1992
Maine Maximum Exposure Guidelines
(MEGs)
Relevant and
Appropriate
MEGs are the Bureau of Health's recommendations for concentrations of
chemical contaminants in drinking water. MEGs are health-based guidelines and
are not legally enforceable.
2000
Maine Maximum Exposure Guidelines
(MEGs)
To be considered
MEGs are the Bureau of Health's most recent recommendations for
concentrations of chemical contaminants in drinking water. MEGs are health-
based guidelines and are not legally enforceable.
-------
TABLE 8: IDENTIFICATION OF ACTION-SPECIFIC ARARs
REQUIREMENT
REQUIREMENT SYNOPSIS 1
GROUNDWATER
Federal Regulatory Requirements
TSCA (15 USC §§ 2601-2692) and
Polychlorinated Biphenyls (PCBs) Regulations
(40 CFR 761: Subpart G, PCB Cleanup Policy;
and Subpart C and D, Markings, Storage and
Disposal)
These requirements apply to the marking, storage, disposal, and cleanup of PCBs greater than 50
ppm that occur after their respective effective dates. The PCB Spill Cleanup Policy, Subpart,
applies to spills of PCB greater than 50 ppm that occurred after its effective date (i.e., May 4,
1987).
U.S. Department of Transportation Rules for
Transportation of Hazardous Materials (49
C.F.R. Parts 107, 171.1-172.558)
This regulation outlines procedures for the packaging, labeling, manifesting, and transportation
of hazardous materials. If residuals from groundwater treatment and/or recovered free product are
classified as hazardous, the materials will be packaged, manifested, and transported to a licensed
off-site disposal facility in compliance with these regulations.
USEPA RCRA - Standards Applicable to
Generators of Hazardous Waste (40 CFR Part
262)
This requirement sets standards for generators of hazardous waste that address (1) accumulating
waste, (2) preparing hazardous waste for shipment, and (3) preparing the uniform hazardous waste
manifest. These requirements are integrated with DOT regulations. Any RCRA hazardous wastes
being shipped off-site must be shipped in proper containers that are accurately marked and labeled,
and the transporter must display proper placards. All waste shipments must be accompanied by
an appropriate manifest.
USEPA RCRA - Standard Applicable to
Transporters of Hazardous Waste (40 CFR Part
263)
These regulations outline the standards for transportation of hazardous waste off-site. Transporters
of hazardous waste must comply with manifest, record keeping, and reporting requirements set
forth in these rules. These requirements will be attained through compliance with U.S. DOT Rules
for Transportation of Hazardous Waste.
-------
USEPA Guidance for Evaluating Technical
Impracticability of Groundwater Restoration
(9234.2-25).
Consistent Implementation of the FY 1993
Guidance on Technical Impracticability of
Groundwater Restoration at Superfund Sites
(9200.4-14)
Use of Monitored Natural Attenuation at
Superfund, RCRA Corrective Action, and UST
Sites (9200.4-17P)
Overview of ARARs, focus on ARAR Waivers
(OSWER 9234.2-03/FS)
This guidance clarifies how USEPA will determine whether groundwater restoration is technically
impracticable and what alternative measures or actions must be undertaken to ensure that the final
remedy is protective of human health and the environment.
This memorandum outlines the basic process for evaluating at Tl decision document and is
intended to promote technically sound, nationally consistent implementation of the Tl guidance.
This directive clarifies ERA's policy regarding the use of monitored natural attenuation for the
cleanup of contaminated soil and groundwater in the Superfund program (among others).
This memorandum provides an overview of ARARs, with a focus on ARAR waivers.
|| State of Maine Regulatory Requirements
Waste Discharge Licenses (38 M.R.S.A. §
413)
Maine Hazardous Waste, Septage, and Solid
Waste Management Act Title 38, Chapter 13
and MEDEP Regulations, Chapters 800-802,
850 851 853-857^
Direct or indirect discharges to the waters of the state require a license.
The rules provide a comprehensive program for handling, storage, and record keeping at hazardous
waste facilities. They supplement the RCRA regulations.
-------
- ',: -4
1 * f ~ *.- *. ~I
<.* *. '
1 f "
Allr.llCTA
.-
:
"SITE LOCATION
FEET
SOURCE: USGS TOPOGRAPHIC MAP
A'J'JUSTA, MAINE / TOGUS POND. MAINE
7.5 VIIN. SERIES, 19S8 LAND (N^O INTERNATIONAL, LTD.
AWOOCARD & CURRAN
SITE LOCATION MAP
CFNTRAL MAINE
AUGUSTA.
O'CONNOR COMPWKY
5UPCPFUNQ SITE
FIGURE t
-------
LEGEND
-£&- REMOVE 0)1 AND OBSERVE OIL
\ RECOVERY
LONG TERM MONITORING LOCATION
ABANDON DURING SOURCE CONTROL.
£L_
SITE FENCE
TRANSFORMER WORK AREA
SUPERFUND SITE BOUNDARY
:
'
100 itAf; FLOOD Leva.
UAFPFP BY FFUA
.WPHDMHATE METHODS
UPLAND
MARSH
AREA
r
-------
-
i \ -v \ / i ' ' r
M > itfJ11 tH
" N ,1 » /'! ! \\\V
1^:1 ;
-------
5UPERFUND SITE BOUNDARY
AND RESTRICTIVE COVENANT
\
i
X
_ . - ..u9cu IK*
- 120'
El!
|
BOUN
COVE
u
0.
3
AINE PO
A, MAIMC
Zlu
zr.
o =
WK rt«;tP
mil Ji;'i .'".
Jl£ ' ^.t^
fIGURE*
-------
N /
WTW.J kiista
-------
SM4JBW'U!$
b \\\fe_-::fo^oiwER , 41
M \rn\\ J^-nV-"''' / W\ \
:^ "/AV-.-
i x«j'j» s vr-C
I/ .^S^ L ' -.^ -
\" /^vk%,
1 \
.1
i \
1 i
i i
+
o
5J«rr OBI
rVElJHE
.p rt N
wf ***. _^- aSs Ss '-j'/'f F'-t I "f I /I
1 ^^mmf'^l
, i,tuSw/'VC
-FORMER '^X(J .' / ," / / ,' f ' S ' '/
:^|:;: ^i^jf^f
//V'/;! ? }J!$f'~^\ ' ,' I } I
LOWER:
UGOON
\ '
\ ^ K \
glGGS -
6ROOK
i---
s-1
NOTES:
* TOPOGRAPHIC INFORMATION IS APPROXIMATE.
TOPOGRAPHIC INFORMATION HAS BEEN
COMPILED FROM ORIGINAL SITE PLAN AND
1999 SURVEY OF REMEDIATED AREA
801
40"
160'
EAR SCALE
I" = BiT
\AOOrARD &CURR AN
Sclanco
SITE SETTING
AUGUSTA,
PDVffR COMPANY
art
FIGURE 6
-------
BOR'NG TC INVESTIGATE MIGRATION
PATHWAYS DOWN GRADIENT Of SOURCE
CONTROL AREA
SHALLOW CROUNOWATER
MOMTORIfC- WaL WSTALLED IN 1986
E.C- JORDAH STUDY
OBSERVATION WELL AND MONITORING
INSTALLED BY C£!
-------
225
-1225
220
.'vx
.
i.4 ' -,
'.. .
. -
SECTION A-A'
SCALE 1'=W HORIZ
1"=+' VERT
LEGEND
TlLi
CLAY
BEDROCK
Ei
"
-
i
O
o
ll
in
V)
«n
o
g
o
C3
o
_l
o
Ul
JO! Ml mt
i»t 5r'
r.i.i. r' n. 11
-------
SOLE: 1'=40 HORIZ
r-30* VERT
-------
12U
SECTION C-C'
SCW.E: r=«' HCKZ
r-20' VERT
120
LEGEND
TILL
CLAY
BEDROCK
»!|
'II
So
Uc
oi
!&F
u
o
u
u
i/i
o
LL
-------
Original includes color coding.
:, Inferred Residual Oil
Distribution
Figure 11
Upland Marsh
Residual Oil Distribution
Central Maine Power Co,
WOODARD&CURRAN
A UWO* 111 we Sta e I ri r-te
-------
B
B1
225
225
Current Surface Elevation
I
ra
>
I
200
R = Refusal
^SJJS Residual OH
' Present
NOTE;
Previous grade Una is projected on to !ha cross section
from Uw ctos&st grid location where a measuremenl was
taken tralore ano during source control For this reason
Che limit oi excavation and Till ctoplhs may not mulch
Figure 12
Vertical Residual Oil Distribution
along Cross Section B-B'
Central Maine Power Co.
WOODARD^CURRAN-
-------
A'
Current Surface Elevation
0 ^^fv7^>J "~ ~~ *--.
-. -. -. t. \ -
"": -- - ' - .
..."--!_ i ' " * ^~
. ^ww*»
Deslocsteel S Us
arid
R = Refusal
-------
22D
215
210
01
£
c
s
1
iB
205
200
195
Limit of Excavation
Current Surface Elevation
Bedrock
Dosiccoted
5il:r: and
Clays
Sufi SiHs
and Clays
-> I
220
216
£
S
2D5
200
195
R = Refusal
>5WSSS Residual Oil
!"' Present
NOTE:
Proviou* grade llrvo Is projedEd on to the cross sedion
(ram Die closest grid location where a measurement was
1aken before and dining source control. Far Uiis raasan
Die limit of excavation anr) fill depths may not match
Figure 14
Vertical Residual Oil Distribution
along Cross Section C-C'
Central Maine Power Co,
WOODARD^CURRAN I
-------
BORING TO INVtST.GATE MIGRATION
PATHWAYS DCmN GRAOtENT OF
SOURCE CQNTRO, ARIA
SHALLOW GSiOUNDWATER
MOWTO^NG V^U INSTALLED
1986 EX. JORDAN STUDY
OBSERVATION *ELL AND U-3WTORII4C
WELL INSTAiUD BY G£l
-------
BORING TO INVESTIGATE
PATHWAYS DO'*N GRADLN1 'OF
SOURCE CONTROL AREA
SHALLOW CRQUNDWATFR MtMTCHHtG
WELL
MONITORING WKLL INSTALLED IN
1986 E C, JORDAN STUDY
OBSERVATION KtL. AND MONITORING
WO! INSTALLED 9Y GD
GROUNDWATER FLOW
i
-------
Row of
Conominanis during
Salvage Operation
Pefehed WatH
Table on Bedroch
Burrock Ridge
Inhiblbng Fltxnv
.uward Riggs Brook
Fracture
with RasHduai Oil
Figure 17
Conceptual Hydrogeologic Model
Prior to Source Control
WOODARD^CURRAN
-------
Perched
Water TaCie
on Sedrocic
Reconstructed
WeUsnd
Water
Gravel Fill after
il Excavation
Perched Water
TabSe on Bedrock
Bedrock Ridge
Inhibiting Flow
toward Rigus Biook
Desiccated Fracture
wilh Residual Oil
Figure 18
Conceptual Hydrogeologic Model
After Source Control
20SK1
-WOODARD&CURRAN
-------
O'CONNOR SUPERFUND SITE
OPERABLE UNIT-2
September 2002 ROD AMENDMENT
APPENDIX A - RESPONSIVENESS SUMMARY
Comments Received on the June 2002 Proposed Plan for the O'Connor Site
1. Comments from Community Members
No comments were received from the community during the July 9, 2002 hearing for the
Proposed Plan.
Several comments were voiced during the information meeting held on June 24, 2002 and
are summarized below.
Community member: In discussing the technical impracticability of removing the oil, different
technologies were suggested which should perhaps be considered to clean up the residual oil.
EPA's Response: Although these suggestions, including the controlled blasting of the bedrock as
would be done in a quarry operation, were not looked at in the TI evaluation, EPA believes the
difficulties posed by the geology and hydrology of the site would be the same as for any of the
eighteen technologies considered in the TI. These limitations include:
residual oil tied up in fractures in the clayey soils and in the bedrock;
limited groundwater recharge to the source area so that there is limited flushing; and
the relatively impermeable clay limits the effectiveness of in-situ application of oxidizing
agents or other compounds.
The possibility of further excavation of the soil with the residual oil was evaluated as part of the
TI process. In a way, it posed a similar question that would be asked for removal of the
bedrock: how would the limits of excavation (or blasting) be determined? The source control
effort showed through extensive testing that the cleanup standards for the soils were met. In
many cases, the results were below the laboratory detection limit. So with the soils already
below the detection limit, sampling would not provide a method to determine the extent of any
excavation (or blasting). EPA believes this would lead to arbitrary excavation and hence it
would be difficult to implement, difficult to estimate costs, and difficult to provide an approach
to assess its effectiveness. Consequently, this alternative was screened out during the TI
evaluation.
-------
Community member: Several comments were made that the nine criteria used in selecting a
remedy needed to be expanded to ten, to look at the impact of a Superfund site on property
values. Additionally, there was the desire that EPA direct the City of Augusta to provide tax
relief for the surrounding properties.
EPA's Response: EPA is aware of concerns raised at this site regarding the impact of having a
Superfund site as a neighbor - this is a concern heard across the country. EPA has made changes
in its policies regarding its approach to adjacent properties where contamination has come to be
located, and EPA has studied the economic impact of Superfund sites on property values, but as
pointed out by Maine DEP at the public meeting, the Superfund law does not provide for any
method to address this issue. This issue may be more properly addressed on the state and local
levels. However, EPA hopes that by addressing the problems at the Site in a way that protects
human health and the environment in the long term there will ultimately be a positive impact in
the community.
Community member: Several long-time community members asked about the impact on Riggs
Brook, tying in their recollections of oil being visible in the brook and far downstream of the
site. In addition, questions were asked regarding the appropriateness of sampling fish when
perhaps other organisms might provide a better indication of PCB-contamination
EPA's Response: EPA acknowledges that conditions at the O'Connor property impacted other
areas, such as Riggs Brook. However, the current data has indicated that the PCB concentrations
are quite low where groundwater discharge to Riggs Brook is occurring and that there does not
appear to be any more overland transport from the source area to Riggs Brook.
Monitoring well MW-106B is a bedrock well located in the Riggs Brook wetlands and is a
flowing artesian well - that is, water flows out of the well head at the ground surface. Sampling
for the past several years have shown low levels of contamination which are below the ROD
performance standards. Yearly sediment sampling has indicated that PCB concentrations are
typically below the trigger level of 5 ppm and often below the clean up goal of 1 ppm. Analysis
of the data suggests that the concentrations in both groundwater and sediment are decreasing and
EPA anticipates that the concentrations will continue to decrease following the source control
remedial action.
The use offish rather than other organisms as an indicator of PCBs was determined at the time
of the 1989 ROD. Personnel from U.S. Fish and Wildlife Service (USFWS) and National
Oceanic Atmospheric Administration (NOAA), as natural resource trustees, were involved with
this aspect of the remedy selection. As they are the individuals with the expertise in this field,
selection offish was based on their knowledge of PCB bioaccumulation. Personnel from
USFWS continue to be involved with the Riggs Brook monitoring as well as EPA and Maine
DEP ecological risk assessors. It is noted that several species offish have been collected as part
of the monitoring program.
Community member: Concern was raised about the prospect that contaminated groundwater may
-------
pass beyond the CMP property to potentially impact other properties.
EPA's Response: The highest priority in selecting a remedy is to ensure that it is protective of
human health as well as the environment. With the acknowledgment that it is technically
impracticable to clean up the groundwater beneath a portion of the site, EPA must select a
remedy that prevents further migration of the contamination, and Maine DEP strongly agrees
with this. EPA believes the selected remedy does this. Concentrations at monitoring wells
MW-106A and MW-106B, located in the Riggs Brook wetlands, plus the wells downgradient of
the TWA-II area have been meeting the performance standards set in the ROD for the past
several years. EPA believes that the groundwater system has reached equilibrium and that
contamination will not move beyond the CMP property. However, should the concentrations
change in these wells, and residential wells be installed in adjacent properties, then EPA would
have these wells tested.
2. Comments from Maine Department of Environmental Protection
At the hearing for the Proposed Plan, Maine DEP entered a statement into the site record. The
State noted the following concerns and stated that their concurrence on the ROD amendment
was contingent on these concerns being addressed.
Maine DEP: USEPA must better identify and define the criteria for discontinuing use of the
VER system.
EPA's Response: In the Proposed Plan, EPA stated the active recovery of oil using the VER
would continue on an annual basis as long as it was practical. This ROD amendment provides
more detail regarding the VER application. It sets forth a framework under which the VER will
operate, states that it will be operated for the next five years, and that the reevaluation of its
operation will be tied in with the next five-year review scheduled for summer 2007.
Maine DEP: All site work will be performed in compliance with the revised cleanup plan and all
applicable standard operating procedures, laws, and regulations.
EPA's Response: All work performed onsite will follow approved work plans and all applicable
requirements.
Maine DEP: MEDEP will be given at least 2 weeks notice prior to each sampling event.
EPA's Response: This will be addressed in any enforcement agreement that is entered into to
conduct the remedy selected in this ROD Amendment.
Maine DEP: It must be periodically demonstrated that there is a continuous twelve inches of
clean soil over the Designated Area. The details of such demonstration will be established prior
-------
to the finalization of the ROD Amendment.
EPA's Response: As part of the change in the soil remedy, as documented in the 1994 BSD,
twelve inches of clean soil were to be placed over the designated area. This soil, defined as
containing less than one ppm of PCBs, was to be brought in from offsite. Concurrent with the
BSD, Maine DEP and CMP signed a Restrictive Covenant which states that CMP or subsequent
owner "shall maintain all drainage ways... permeable or impervious caps or covers (including
areas covered by topsoil or other clean fill)"
EPA agreed to address this issue concurrently with the TI evaluation. As noted in Section IV.
Scope and Role of Operable Unit, of this ROD Amendment, operation and maintenance will
include provisions for periodic monitoring of the soil cover as well as random sampling of the
surface soils to be performed at the time of the five-year reviews. Maine DEP indicated this was
an acceptable resolution for this issue.
Maine DEP: Clarify, by incorporation into the ROD Amendment, that the clean up goal for
PCBs in sediment is actually 1 ppm, not 5 ppm. However, MEDEP agrees that the 5 ppm
trigger level for remedial action is acceptable.
EPA's Response: EPA has clarified in Section IV. Scope and Role of Operable Unit of this ROD
amendment that the clean up goal for PCBs in Riggs Brook and associated wetland sediments is
1 ppm.
A review of the 1991 Consent Decree and the 1994 Revised Statement of Work found that
neither document provides any criteria to define a hot spot excavation. Similarly, the approved
October 1997 Final Riggs Brook Sediment and Biota Sampling and Analysis Plan is also silent
on this issue. To clarify this, the clean up goal for Riggs Brook and associated wetland sediment
is 1 ppm, but should a hot spot excavation occur, the extent of that excavation would be to less
than 5 ppm.
This is consistent with the intent of the 1989 ROD to protect ecological receptors. As noted in the
1989 ROD, in addition to the clean up goal for sediments, the trigger for additional sampling is also tied
to the goal of less than 2 ppm for PCBs in fish tissue samples. Should this sampling indicate greater than
2 ppm "then a more rigorous sampling effort of such contamination will be conducted to determine the
need for and/or extent of further remedial action to be undertaken within Riggs Brook, if any". (1989
ROD, page 47)
Maine DEP: All significant erosion occurring in the Designated Area on site will be addressed in
a timely manner to prevent exposure to levels of PCB above 1 ppm and lead above 248 ppm.
EPA's Response: See the response above regarding maintenance of the soil cover.
Comments from the Settling Party
Central Maine Power Co. (CMP) provided comments during the public comment period for the
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site record in response to two of Maine DEP's comments. CMP noted it supports the amended
ROD for the O'Connor site.
CMP: Cover Soil Effectiveness. The Source Control Remedial Action (SCRA) required that a
12-inch cover of soil containing less than 1 ppm of PCBs be placed over the Designated Area ,
the portion of the site where residual PCB concentrations in the soil could be up to 10 ppm.
That cover soil was placed during SCRA, and a cover crop of vegetation was established to
stabilize the soil and control erosion. The operating plan requires periodic inspections of the site
by CMP to identify any areas of erosion, and remedial action to be taken to repair those areas.
To address the concern that long-term gradual erosion could reduce the thickness of soil cover in
some areas without being visually obvious, discussions were held with Maine DEP and EPA to
develop a sampling program for the soil cover.
EPA's Response: As stated above, operation and maintenance will include confirmatory
sampling of the soil cover coincident with the five-year reviews for the site. Ten locations will
be randomly generated for sampling, using the grid nodes from the SCRA. Composite samples
from 4-8" below grade will be collected and analyzed for PCBs. Should the results be above 1
ppm, EPA, Maine DEP, and CMP will determine appropriate steps to take.
CMP: Riggs Brook PCB Concentrations. The US Fish and Wildlife Service (USFWS)
evaluation of Riggs Brook discussed in the 1989 ROD suggested a target cleanup level for PCBs
of 1 ppm. However, the ROD selected a remedy for the site that allowed the existing maximum
of 5 ppm PCBs in the sediment to remain because the short-term impacts of excavation would be
more damaging to the wetland area. The selected remedy required that a 10-year monitoring
program be instituted, and that a more rigorous sampling effort be undertaken if sampling found
sediment values above 5 ppm or fish tissue samples above 2 ppm. The results of this more
rigorous sampling would be used to determine if additional remediation of Riggs Brook were to
be required. Because excavation in Riggs Brook could cause short-term damage to the
ecosystem, as recognized by the ROD, CMP believes the limits of any remediation should be
established with respect to meeting the 5 ppm target level for PCBs, and not necessarily the
1 ppm target suggested by USFWS if doing so creates an unacceptable short-term impact to
Riggs Brook.
EPA's Response: EPA agrees that the limit of any excavation based on an exceedance of 5 ppm
would be to get below 5 ppm. However, the possibility exists that the levels identified in fish
tissue sampling could be greater than 2 ppm yet the sediment data be below 5 ppm. Should such
a situation arise, then the triggering of further sampling with possible remedial actions is
appropriate.
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O'CONNOR SUPERFUND SITE
OPERABLE UNIT 2
September 2002 ROD AMENDMENT
APPENDIX B- ADMINISTRATIVE RECORD INDEX
4. FEASIBILITY STUDY (FS)
1. FACT SHEET: EPA PROPOSES TO AMEND THE CLEAN-UP PLAN FOR THE F. O'CONNOR
SUPERFUND SITE.
AUTHOR: US EPA REGION 1
DOC ID: 32499 06/01/2002 15 PAGES
2. REPORT: TECHNICAL IMPRACTICABILITY EVALUATION FOR OU-2 MANAGEMENT OF
MIGRATION (WITH TRANSMITTAL) [1 OF 2].
TO: CENTRAL MAINE POWER COMPANY
AUTHOR: WOODARD & CURRAN INC
DOC ID: 31877 06/01/2002 135 PAGES
3. REPORT: TECHNICAL IMPRACTICABILITY EVALUATION FOR OU-2 MANAGEMENT OF
MIGRATION, APPENDICES [2 OF 2].
TO: CENTRAL MAINE POWER COMPANY
AUTHOR: WOODARD & CURRAN INC
DOC ID: 31881 06/01/2002 303 PAGES
6. REMEDIAL DESIGN (RD)
1. REPORT: MANAGEMENT OF MIGRATION FLOATING FREE PRODUCT OIL STUDY.
AUTHOR: ALTON P. DAVIS, GEI CONSULTANTS INC
JOANNE O. MORIN, GEI CONSULTANTS INC
MURIEL S. ROBINETTE, GEI CONSULTANTS INC
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DOC ID: 31925 02/14/1993 79 PAGES
2. REPORT: REMEDIAL DESIGN/REMEDIAL ACTION REVISED STATEMENT OF WORK.
AUTHOR: US EPA
DOC ID: 32078 10/20/1994 50 PAGES
3. REPORT: MANAGEMENT OF MIGRATION GROUNDWATER MONITORING PROGRAM SAMPLING
AND ANALYSIS PLAN, VOLUME I OF II.
AUTHOR: WOODARD & CURRAN INC
DOC ID: 31933 12/01/1996 156 PAGES
4. LETTER: AMENDMENTS TO THE MANAGEMENT OF MIGRATION SAMPLING AND ANALYSIS
PLAN.
TO: ERIN HESKETT, US EPA REGION 1
AUTHOR: JAMES M. MOODY, WOODARD & CURRAN INC
DOC ID: 31953 03/14/2000 10 PAGES
7. REMEDIAL ACTION (RA)
1. REPORT: VACUUM ENHANCED RECOVERY PILOT TEST, PHASE 1 INSTALLATION AND
OPERATION REPORT (WITH TRANSMITTAL).
AUTHOR: WOODARD & CURRAN INC
DOC ID: 31937 12/01/1996 126 PAGES
2. REPORT: DATA COLLECTION AND INTERPRETATION OF THE PHASE 2 OPERATION OF
THE VACUUM ENHANCED RECOVERY (VER) SYSTEM AT THE O'CONNOR SITE IN
AUGUSTA, MAINE.
TO: ROSS GILLELAND, US EPA REGION 1
AUTHOR: ERIC T CARLSON, WOODARD & CURRAN INC
DOC ID: 31948 06/27/1997 33 PAGES
3. REPORT: MANAGEMENT OF MIGRATION COMPREHENSIVE EVALUATION.
AUTHOR: WOODARD & CURRAN INC
DOC ID: 31957 08/01/1997 185 PAGES
4. MEMO: FINAL INSPECTION OF THE SOURCE CONTROL REMEDIAL ACTION.
TO: MARY JANE ODONNELL, US EPA REGION 1
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AUTHOR: ROSS GILLELAND, US EPA REGION 1
DOC ID: 31996 12/01/1997 2 PAGES
5. REPORT: WETLAND CONSTRUCTION MONITORING REPORT.
TO: CENTRAL MAINE POWER COMPANY
AUTHOR: SMART ASSOCIATES
DOC ID: 31992 03/12/1998 49 PAGES
6. REPORT: FINAL SOURCE CONTROL REMEDIAL ACTION REPORT [1 of 2].
AUTHOR: WOODARD & CURRAN INC
DOC ID: 31985 09/01/1998 421 PAGES
7. REPORT: FINAL SOURCE CONTROL REMEDIAL ACTION REPORT [2 of 2].
AUTHOR: WOODARD & CURRAN INC
DOC ID: 31991 09/01/1998 358 PAGES
8. LETTER: OIL STUDY IN THE UPLAND MARSH AREA AT THE CMP O'CONNOR SITE.
TO: ROY KOSTER, CENTRAL MAINE POWER COMPANY
AUTHOR: ERIC T CARLSON, WOODARD & CURRAN INC
DOC ID: 31997 01/26/1999 19 PAGES
9. REPORT: 1998 WETLAND CONSTRUCTION MONITORING REPORT.
TO: CENTRAL MAINE POWER COMPANY
AUTHOR: SMART ASSOCIATES
DOC ID: 32028 04/08/1999 31 PAGES
10. REPORT: 1999 RIGGS BROOK SEDIMENT MONITORING REPORT.
TO: ROY KOSTER, CENTRAL MAINE POWER COMPANY
AUTHOR: HENRI J. VINCENT, WOODARD & CURRAN INC
DOC ID: 32059 02/01/2000 103 PAGES
11. REPORT: 1999 WETLAND CONSTRUCTION MONITORING REPORT.
TO: CENTRAL MAINE POWER COMPANY
AUTHOR: SMART ASSOCIATES
DOC ID: 32024 08/15/2000 39 PAGES
12. LETTER: COMMENTS ON 1999 WETLAND CONSTRUCTION MONITORING REPORT (DATED AUG 15, 2000).
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TO: CORNELL ROSIU, US EPA REGION 1
ERIN HESKETT, US EPA REGION 1
AUTHOR: STEVEN E MIERZYKOWSKI, US DOI/US FISH & WILDLIFE SERVICE
DOC ID: 32022 10/19/2000 5 PAGES
13. REPORT: 2000 WETLAND CONSTRUCTION MONITORING REPORT.
TO: CENTRAL MAINE POWER COMPANY
AUTHOR: SMART ASSOCIATES
DOC ID: 32020 03/13/2001 43 PAGES
14. LETTER: COMMENTS ON 2000 WETLAND CONSTRUCTION MONITORING REPORT (DATED
MARCH 13, 2001).
TO: CORNELL ROSIU, US EPA REGION 1
TERRENCE R CONNELLY, US EPA REGION 1
AUTHOR: STEVEN E MERZYKOWSKI, US DOI/US FISH & WILDLIFE SERVICE
DOC ID: 32012 06/29/2001 4 PAGES
15. REPORT: DRAFT 2000 RIGGS BROOK SEDIMENT AND BIOTA MONITORING REPORT.
TO: ROY KOSTER, CENTRAL MAINE POWER COMPANY
AUTHOR: HENRI J. VINCENT, WOODARD & CURRAN INC
DOC ID: 32058 07/01/2001 159 PAGES
16. REPORT: REVISED LONG-TERM GROUNDWATER QUALITY MONITORING PROGRAM AND
PHASE III VACUUM ENHANCED RECOVERY OF OIL WORK PLAN.
AUTHOR: WOODARD & CURRAN INC
DOC ID: 32061 07/01/2001 28 PAGES
17. REPORT: MANAGEMENT OF MIGRATION, SAMPLING AND ANALYSIS SEMI-ANNUAL REPORT.
AUTHOR: WOODARD & CURRAN INC
DOC ID: 32066 10/01/2001 112 PAGES
18. REPORT: DRAFT 2001 RIGGS BROOK SEDIMENT MONITORING REPORT.
AUTHOR: WOODARD & CURRAN INC
DOC ID: 32062 12/01/2001 118 PAGES
19. REPORT: DRAFT VER PHASE III REPORT.
AUTHOR: WOODARD & CURRAN INC
DOC ID: 32069 12/01/2001 28 PAGES
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20. LETTER: COMMENTS ON DRAFT VER PHASE III REPORT.
TO: TERRENCE R CONNELLY, US EPA REGION 1
AUTHOR: WILKES B HARPER, ME DEPT OF ENVIRONMENTAL PROTECTION
DOC ID: 32072 02/16/2002 2 PAGES
10. ENFORCEMENT/NEGOTIATION
1. LITIGATION: CONSENT DECREE, UNITED STATES OF AMERICA, PLAINTIFF, V.
CENTRAL MAINE POWER COMPANY, DEPENDENT.
TO: JOE C. COLLIER, CENTRAL MAINE POWER COMPANY
AUTHOR: CYNTHIA S HUBER, US DEPT OF JUSTICE
ELISSA TONKIN, US EPA REGION 1
JULIE BELAGA, US EPA REGION 1
RICHARD B STEWART, US DEPT OF JUSTICE
DOC ID: 32075 07/26/1990 80 PAGES
13. COMMUNITY RELATIONS
1. FACT SHEET: O'CONNOR COMPANY MAINE, EPA ID# MED980731475.
AUTHOR: US EPA REGION 1
DOC ID: 32080 01/01/1996 3 PAGES
2. LETTER: LETTER TO NEIGHBORS/ABUTTERS OUTLINING THE CONTINGENCY REMEDY
WITH A QUESTIONNAIRE AND 'FACTS AT A GLANCE SHEET' [INCLUDING FAX
TRANSMITTAL SHEET].
AUTHOR: ROY LANE, CENTRAL MAINE POWER COMPANY
DOC ID: 32083 03/26/1996 6 PAGES
3. MEMO : RESPONSES TO MARCH 22, 1996 NEIGHBOR/ABUTTER QUESTIONNAIRE.
TO: ROSS GILLELAND, US EPA REGION 1
AUTHOR: TERENCE R. PEACOCK, CENTRAL MAINE POWER COMPANY
DOC ID: 32085 06/10/1996 26 PAGES
4. LETTER: UPDATE ON COMMUNITY RELATIONS.
TO: KATHLEEN B. FULLER, AUGUSTA (ME), CITY OF
AUTHOR: ROY LANE, CENTRAL MAINE POWER COMPANY
10
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DOC ID: 31998 07/10/1996 2 PAGES
5. PUBLIC MEETING RECORD: SUMMARY OF CLEANUP ACTIVITY, PREPARED FOR SITE
NEIGHBORS AND ABUTTING LANDOWNERS.
AUTHOR: ROY LANE, CENTRAL MAINE POWER COMPANY
DOC ID: 32000 07/24/1996 10 PAGES
6. PUBLIC MEETING RECORD: PUBLIC MEETING, AMERICAN LEGION POST 205, AGENDA.
AUTHOR: ROY LANE, CENTRAL MAINE POWER COMPANY
DOC ID: 32002 12/12/1996 12 PAGES
7. NEWS CLIPPING: EPA TESTS CONY ROAD HOMES.
AUTHOR: DAVE CHEEVER, KENNEBEC JOURNAL
DOC ID: 32004 06/26/1997 2 PAGES
8. NEWS CLIPPING: CITY JUNKYARD OFFICIALLY CLEAN.
AUTHOR: GARY J. REMAL, KENNEBEC JOURNAL
DOC ID: 32005 11/13/1997 2 PAGES
9. NEWS CLIPPING: WEEKLY UPDATE, O'CONNOR SUPERFUND CLEAN-UP CELEBRATED.
AUTHOR: CENTRAL MAINE POWER COMPANY
DOC ID: 32006 11/20/1997 2 PAGES
10. FACT SHEET: EPA TO REVIEW PROGRESS OF CLEANUP AT O'CONNOR SUPERFUND SITE.
AUTHOR: ALICE KAUFMAN, US EPA REGION 1
DOC ID: 32008 05/08/2002 2 PAGES
20. RECORDS MANAGEMENT
1. LIST : LIST OF GUIDANCE DOCUMENTS.
AUTHOR: US EPA REGION 1
DOC ID: 32519 06/20/2002 1 PAGE
11
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O'CONNOR SUPERFUND SITE
OPERABLE UNIT 2
September 2002 ROD AMENDMENT
APPENDIX C - STATE CONCURRENCE LETTER
12
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STATE OF MAINE
DEPARTMENT OF ENVIRONMENTAL PROTECTION
ANGUS S. KING, JR. MARTHA KIRKPATRICK
COMMISSIONER
GOVERNOR
September 19,2002
Mr. Richard Cavagnero
Acting Director - Office of Site Remediation and Restoration
US EPA
One Congress Street - Suite 1100 (HBT)
Boston, MA. 02114-2023
Regarding: O'Connor Junkyard Superfund Site
(F. O'Connor Company Superfund Site)
Augusta, Maine
Dear Mr. Cavagnero,
The Maine Department of Environmental Protection (MEDEP) has completed its review of the Record of
Decision Amendment - Operable Unit 2 - for the F. O'Connor Company Superfund Site (Site) in Augusta,
Maine dated September 2002.
Based on this review the MEDEP is pleased to provide its concurrence on, with caveats, the revised remedy
selected for OU-2. This remedy relies on active and passive oil recovery, long term monitoring of the
groundwater, and land use restrictions specified in a Declaration of Restrictive Covenants recorded at the
Kennebec County Registry of Deeds on September 13, 2002 - Book 7058, page 42.
This concurrence is contingent upon the following caveats:
1 . Finalize an Operations and Maintenance Plan (O&M).
The O&M must be finalized to the satisfaction of the MEDEP within a reasonable time frame
following our concurrence with the ROD Amendment.
A draft O&M was submitted to MEDEP on June 6, 2002 by Woodard and Curran (W&C) on
behalf of Central Maine Power Company (CMP). This plan failed to address the monitoring and
maintenance requirements regarding the clean soil cover overlying the Designated Area (DA); therefore,
it was rejected by MEDEP. The Designated Area is a subsection of the property where soils
contaminated with up to 10 parts per million (ppm) of polychloronated biphenyls (PCBs) and 248 ppm
lead were left on site.
During a meeting August 14, 2002 held onsite between representatives of CMP, W&C, and
MEDEP, it was unanimously agreed that the draft O&M wi 11 be revised to include provisions for periodic
monitoring and maintenance of the DA cover. Specifically, sampling of the DA cover will be performed
to coincide with each 5 Year Review process beginning in 2007. A total of 10 sampling points will be
chosen randomly for each sampling event. Discrete soil samples will be collected from 4" to 8" below
the surface of the DA and analyzed for PCBs. MEDEP will be given at least 2 weeks notice prior to
each sampling event.
" TATHOUSE STATION BANGOH ''"'^^ROA n uT^ENTRAL DRIVE, SKYWAY PARK
OAO, H 04,0,
RAY HI HG HOSPITAL ST. (207) 941-4S70 FAX: (207) 941-4584 (2O7) HZZ-6K50 FAX: (207) 821-6)03 (207) 764-0477 hAX: (207) 764-150,
prinH-'d oil recycled paper
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2. Establish Criteria for Termination of the Vacuum Enhanced Recovery System (VER)
Based on the site conceptual model, residual oil remains onsite trapped in the clay layers between
the overburden and bedrock. Addition oil may be present trapped in the bedrock fractures. The amount
of this residual oil is unknown; however, it is understood that any reduction in the overall quantity of oil
remaining on site will have a beneficial effect on groundwater quality.
The VER system was first used in 1996. Since then approximately 85 gallons of PCB-
contaminated oil has been recovered through the use of this system However, criteria for continued use
or termination of this system has never been adequately defined.
MEDEP, following discussions with EPA, requires that as long as a significant amount of oil can
be recovered using the VER system, then operation of the VER will continue. A significant amount of
oil is defined as an increase in the amount of oil recovered relative to the amount recovered through
passive methods using absorbent materials. This means that if the VER system is effectively increasing
the amount of oil being passively recovered from a particular well, it will continue to be applied to that
well.
Use of the VER will continue to be used annually until at least the next Five Year Review process
(i.e. 2007). An evaluation will be made at that time to determine if further use of the VER is still
warranted.
3. Continued Adherence to the Existing Long Term Monitoring Program
The O&M also includes a long term monitoring plan requiring bi-annual groundwater sampling on
selected wells. Samples from these wells will be analyzed for PCBs and volatile organic compounds.
This information will be used to evaluate whether the remedy is successful.
Such long term monitoring will continue as long as the groundwater fails to attain all applicable
standards.
4. Consideration of Contingencies in Case the Selected Remedy is Not Successful
In the event the provisions of the selected remedy are not successful, remedial contingency plans
must be considered and implemented as appropriate.
The MEDEP has enjoyed the cooperation of the USEPA in addressing the issues of concern posed by this
Site, and looks forward to ultimately resolving them through this Record of Decision Amendment. If you
need additional information, please do not hesitate to contact Mark Hyland or members of his staff.
Sincerely,
David Lennett
Director, Bureau of Remediation and Waste Management
Martha G. Kirkpatrick, Commissioner - MEDEP
Mark Hyland, Director - Division of Remediation
Denise Messier, Supervisor Superfund and Federal Facilities Unit
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F. O'CONNOR SUPERFUND SITE
OPERABLE UNIT 2
September 2002 ROD AMENDMENT
APPENDIX D - REFERENCES CITED
US Environmental Protection Agency, "Record of Decision Summary O'Connor Company
Superfund Site", September 27, 1989.
, "Consent Decree, United States of America, Plaintiff v. Central Maine Power,
Defendant", Septembers, 1991
, "Explanation of Significant Differences for the F. O'Connor Company Superfund Site",
July 11, 1994.
, "Remedial Design/Remedial Action Revised Statement of Work, O'Connor Company
Superfund Site, Augusta, Maine", October 1994 (SOW is appendix A to CD)
, "Invocation of Contingency Remedy for the F. O'Connor Company Superfund Site",
October 10, 1995.
Woodard & Curran, Inc., "Management of Migration Comprehensive Evaluation, O'Connor
Superfund Site", August 1997
, "Final Source Control Remedial Action Report" September 1, 1998.
, Oil Study in the Upland Marsh Area at the CMP O'Connor Site in Augusta, Maine,
Woodard & Curran, January 1999
, "1999 Riggs Brook Sediment and Biota Monitoring Report, O'Connor Company
Superfund Site", February 2000
, "2000 Riggs Brook Sediment and Biota Monitoring Report, O'Connor Company
Superfund Site", July, 2001
, "Management of Migration Sampling and Analysis Quarterly Report, O'Connor
Company Superfund Site", October 26, 2001
, "2001 Riggs Brook Sediment and Biota Monitoring Report, O'Connor Company
Superfund Site", December 13, 2001
, "Technical Impracticability Evaluation for OU-2 Management of Migration, O'Connor
Company Superfund Site", June 7, 2002
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