J
United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
PB93-964119
EP AlROD/R05-92/208
September 1992
&EPA
Superfund
Record of Decision:
Tar Lake, MI
o ~-Sc EfivlFo~~ Pf@tettiM Agency
- m Hazardous Waste
, . tinformatigftJ Cooter
~ 1 O1estmit--Street ~ 9th Roof
Phj~Q FA 19101
- '
- Hazardous waste Correction
fnformation Resource Center
US EPA Region 3
Philadelphia, PA 19107
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NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement, but adds no further applicable information to
the content of the document. All supplemental material is, however. contained in the administrative record
for this site. .
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REPORT DOCUMENTATION 11. REPORT NO. I 2. 3. Reclplenfs Accession No.
PAGE EPA/ROD/R05-92/208
4. Title and Subtitle 5. Report Date
SUPERFUND RECORD OF DECISION 09/29/92
Tar Lake, MI 6.
First Remedial Action - Final
7. Author(s) 8. Per10rrnlng Organization Rept NO.
9. Per10rrnlng Orgainlzatlon Name and Address 10. ProjectITaskIWork Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponsoring Organization Name and Address 13. Type 01 Report & PerIod Covered
U.S. Environmental Protection Agency 800/000
401 M Street, s.w.
washington, D.C. 20460 14.
15. Supplementary Notes
PB93-964119
16. Abstract (Umlt: 200 words)
The 200-acre Tar Lake site is a former manufacturing site in Antrim County, Michigan,
located 1 mile south of Mancelona, Michigan, near the village of Antrim. Land use in
the area is industrial/residential, with several lakes and ponds in the vicinity of the
site. From 1882 to 1945, the site was the location of iron production by the charcoal
method. In 1910, Antrim Iron Works Company began producing charcoal in sealed retorts
from which pyroligneous liquor was recovered. This liquor was further processed into
calcium acetate, methanol, acetone, creosote oil, and wood tar. Wastes from these
processes were discharged into Tar Lake, a large natural surface depression.
Investigations performed by EPA and responsible parties revealed soil and ground water
contamination with concentrations above federal and state regulatory levels.
Groundwater contamination extends 3.5 miles downgradient from the site, and Tar Lake
has a strong chemical odor. This ROD addresses a final remedy for the soil and tar
sludge, as well as an interim remedy to limi t further contamination of ground water, as
OUI. A future ROD will address OU2 as the final remedy for the ground water
contamination. The primary contaminants of concern affecting the soil, tar sludge, and
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - Tar Lake, MI
Remedial Action - Final
Contaminated Media: soil/sludge, gw
Key Contaminants: VOCs (benzene, toluene, xylenes), other organics (PAHs, phenols)
b. 1den1iflerslOpen-Ended Terms
c. COSA 11 AeId'Group
18. Availability Statement 19. Security Class (This Report) 21. No. 01 Pages
None 56
20. Security Class (This Page) 22. PrIce
1\T {'In ""
ctions ul'lluNAL I"UHM 272 (4-77)
50272-1 01
~
(See ANSI-Z39.18)
See Instru
on Reverse
(Formerly NT1S-35)
Department 01 Commerce
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~
EPA/ROD/R05-92/208
Tar Lake, MI
First Remedial Action - Final
Abstract (Continued)
ground water are VOCs, including benzene, toluene, and xylenesi PAHsi and other organics,
including phenols.
The selected remedial action for this site includes excavation of approximately
30,000 cubic yards of tar sludge and approximately 40,000 cubic yards of contaminated
soil in and around Tar Lake, dewatering via extraction wells to facilitate excavationi
consolidation of excavated materials into two adjoining RCRA containment cells to be
.constructed within the contamination areai and addition of solidification agents, such as
bentonite and cement, which will be added to the tar sludge to give it the physical
stability to support a RCRA cap. Both containment cells will meet RCRA minimum
technology requirements, including double liners, leachate collection systems, and a
ground water monitoring system, and will be capped with RCRA Subtitle C landfill covers.
A ground water pump and treat system will be installed to contain the contaminated ground
water, and a treatability study will be performed during the pre-design stage to
determine the effectiveness of carbon adsorption to meet ground water discharge limits.
Treated water will be reinjected upgradient of the extraction wells to perform a closed
loop system, and institutional controls to restrict ground water usage will be
implemented. The estimated present worth cost for this remedy is $20,100,000, including
an annual O&M cost of $791,800.
PERFORMANCE STANDARDS OR GOALS: All soil and sludge with an excess cancer risk level
greater than 1x10-6 will be excavated from the site. Chemical-specific soil and sludge
clean-up levels were based on the Michigan Environmental Response Act and health-based
criteria and include benzene 0.4 ug/kg; xylenes 6,000 ug/kgi toluene 16,000 ug/kgi
benzo(a) anthracene, benzo(b) fluoranthene, and benzo(k) fluoranthene all at 100 ug/kgi
phenols 6,000 Ug/kgi and 2-methylphenol 8,000 ug/kg. Because the ground water
containment is an interim measure, ground water clean-up standards are waived.
Chemical-specific clean-up levels will be provided in the final action for ground water
onsite.
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DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
Tar Lake
Antrim County, Michigan
STATEMENT OF BASIS AND PURPOSE
This decision docume~t presents the selected remedial action for
the Tar Lake site developed in accordance with the Comprehensive
Environmental Response, compensation, and Liability Act of 1980
(CERCLA), 42 U.S.C. 9601, as amended by the Superfund Amendments
and Reauthorization Act of 1986 (SARA) and is consistent with the
National oil and Hazardous Substances Pollution contingency Plan
(NCP) to the extent practicable.
This decision is based upon the contents of the administrative
record for the Tar Lake site.
The State of Michigan has verbally concurred with u.s. EPA's Record
of Decision. A concurrence letter has not yet been received.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this
site, if not addressed by implementing the response action selected
in this Record of Decision, may present a current or potential
threat to public health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
This operable unit remedial action is the first of two operable
units and was selected to address environmental contamination and
public health risks resulting from releases or potential releases
from Tar Lake.
The NCP is explicit in its stated support of the "bias for action"
approach on Superfund Sites. The "operable unit" is an outgrowth
of this concept and is def ined in the NCP section 300. 5 as
" . . . discrete action that comprises an incremental step toward
comprehensively addressing site problems...". u.S. EPA decided
that for proper management of the Tar Lake Site in an effort to
expeditiously implement site remedy for protection of public health
and the environment, an operable unit was a prudent and appropriate
measure to take. The source is a continuing source of
contamination to the groundwater. This operable unit addresses
source control and interim groundwater containment. The second
operable unit, at the conclusion of the Remedial Investigation/
Feasibility Study, will address the final groundwater remedy for
the site.
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2
The major components of the selected remedy are as follows:
Source Control:
Excavation/consolidation of the tar and all of the
contaminated soils (soils with an excess cancer risk
level greater than 1 x 10-6) in and around Tar Lake
extending to the adjacent landfill. The vertical and
horizontal extent of excavation shall be further defined
during the remedial design. Initial estimates of volume
are 30,000 yd3 of tar and 40,000 yd3 of contaminated
soils. Dewatering shall be done to facilitate the
excavation. The exact number and placement of the
dewatering extraction wells will depend on the areal
extent and depth of contamination.
Consolidation of the tar and contaminated soils in two
adjoining RCRA containment cells constructed in the area
of contamination. The cells shall meet RCRA minimum
technology requirements, which includes at a minimum,
double liners, leachate collection systems, and
groundwater monitoring. The first containment cell shall
be sized to hold the tar, estimated to be 30,000 yd3, and
solidification agents (bentonite and cement) , which shall
be added to the tar to give it the physical stability to
support the weight of a RCRA subtitle C hazardous waste
landfill cover. The second containment cell shall be
sized to hold the contaminated soils. Both containment
cells shall be capped with RCRA subtitle C hazardous
waste landfill covers.
Interim Groundwater containment:
Installation of a groundwater pump and treat system for
the containment of contaminated groundwater and the
treatment of water ponded on Tar Lake. Because this is
an interim measure, groundwater cleanup standards are
waived. The treated groundwater shall be reinjected
upgradient of the extraction wells to form a closed loop
system and shall meet Act 307 Type B levels and shall
comply with the substantive requirements of Act 245.
Implementatiol-: of institutional controls which shall
restrict groundwater usage within the areas of the
existing or potential contaminant plume.
A site evaluation will be performed every five years for a 30 year
period. The purpose of this evaluation is to determine if site
conditions are changing, and if so, what actions may be necessary
to address these changes.
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3
DECLARATION OF STATUTORY DETERMINATIONS
This action is protective of human health and the environment,
complies with (or waives) Federal and state applicable or relevant
and appropriate requirements for this operable unit action, and is
cost-effective. This action satisfies the statutory mandate for
permanence and treatment to the maximum extent practicable for this
operable unit. Due to the large volumes of contaminated media that
would have to be treated and the very high costs (and without
additional environmental benefit), treatment of the tar and
contaminated soils is considered impracticable and not cost
effective. Although the interim groundwater containment utilizes
treatment of contaminated groundwater; overall, treatment is not
employed to an extent whereby it would be considered a principal
element of the remedy.
Thus, the statutory preference for remedies that employ treatment
that reduces toxicity, mobility, or volume as a principal element
is not satisfied by this operable unit. Subsequent actions are
planned to address fully the threats posed by the groundwater at
this site.
Because this remedy will result in hazardous substances remaining
on-site above health based levels, a review will be conducted to
ensure that the remedy continues to provide adequate protection of
human health and the environment within five years after
commencement of the remedial action.
Jtte~k 1, (ffb
Valdas V.
Regional A
u.s. EPA,
amkus
inistrator
egion V
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&EPA
RECORD OF DECISION
DECISION SUMMARY
TAR LAKE SITE
ANTRIM COUNTY, MICIDGAN
prepared by:
u.s. Environmental Protection Agency
Region V
Chicago, Illinois
september 1992
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DECISION SUMMARY
Tar Lake site
I. SITE NAME. LOCATION. AND DESCRIPTION
The Tar Lake site is located in Antrim County, Michigan. The
site occupies over 200 acres just east of Highway 131,
approximately one mile south of Mancelona, Michigan. It is
situated in a rural area near the village of Antrim. The
source area, which covers over 4 acres, contains tar and water
up to a depth of 27 feet. Some of the soil surrounding Tar
Lake is also contaminated.
Figure 1 shows many of the relevant physical site features and
surrounding land. The site itself is characterized by severe
topographic relief. No permanent or intermittent streams are
present and there appears to be no surface run-off from the
site. other site features. include Tar Lake, slag piles,
limestone piles, one sludge pile on the west side of Tar Lake,
and the remains of tank supports and cooling water ditches.
Tar Lake is a large natural surface depression that was
partially filled in with the disposal of tar-like residuals
from a wood charcoal production operation and as a result
became known as "Tar Lake". There is no evidence of
containerized wastes present. The site is characterized by a
chemical odor. Tar Lake appears to have shrunk by more than
50% since the 1930' s according to an evaluation of aerial
photographs. It has been reported that Tar Lake caught fire
in the 1960' s and burned for an unspecified period before
being extinguished by natural action. The fire may be
responsible for some shrinkage considered to have occurred at
Tar Lake.
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
From 1882 to 1945, the site was the location of iron
production by the charcoal method. In 1910, the Antrim Iron
Works company began producing charcoal in sealed retorts from
which pyroligenous liquor was recovered. This liquor was
further processed into calcium acetate, methanol, acetone,
creosote oil, and wood tar. This secondary chemical
manufacturing process produced a waste equivalent to still
bottoms which was discharged into a depression on-site, i.e.
Tar Lake. The chemical plant operated until 1944.
In 1949, the municipal water supply was extended to
village of Antrim and much of the surrounding area.
Tar Lake was proposed for inclusion on the National Priorities
List (NPL) in December 1982. In September 1983, Tar Lake was
listed on the NPL.
the
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2
In 1984, Gulf and Western Manufacturing Company erected a six
foot woven-wire fence topped with barbed wire to secure Tar
Lake from unauthorized access.
In 1985, Environmental and Safety Designs, Inc. (Ensafe)
prepared a Remedial Investigation/Feasibility Study (RIfFS)
work plan for Fifty-Sixth Century Antrim Iron Works Company
(Fifty-Sixth Century), a Potentially Responsible Party (PRP)
at Tar Lake. The final work plan was completed on January 15,
1986. This final RIfFS work plan was incorporated into a
Consent Order between u.S. EPA and Fifty-Sixth Century, which
was effective on April 21, 1986. Under the Consent Order,
Fifty-Sixth Century was to conduct an RIfFS at Tar Lake. The
work plan had the RI being conducted in two phases. The first
phase was the development of a preliminary endangerment
assessment (PEA), which would include limited groundwater
sampling. The second phase, yet to be conducted, was to be a
more detailed investigation based on the findings and results
of the PEA.
During the Phase I RI work, deep and shallow monitoring wells
were installed and a specialized analytical protocol for low
level phenolics was developed. In January 1988, sampling and
analysis of Tar Lake groundwater was performed using the
special analytical protocol and contract Laboratory Program
(CLP) Routine Analytical Service (RAS) organic and inorganic
parameters. The results, which became available in May 1988,
confirmed the presence of classes of phenolic compounds, but
did not identify specific constituents. Four of the
groundwater samples that were collected and analyzed from on-
site wells could not be properly quantified because of
unexpectedly high concentrations. CLP RAS samples indicated
concentrations near or below Contract Required Detection
Limits for benzene, naphthalene, toluene, and ethylbenzene in
three of eight wells. The PEA was submitted on October 4,
1988. The PEA concluded that based on available data, the
phenols in the groundwater posed no endangerment at the
concentrations found. U.S. EPA found the PEA to be deficient
because U.S. EPA believed it inadequately and incompletely
used data collected and the Agency believed the conclusions
drawn were not adequately supported. Consequently, U.S. EPA
did not approve the PEA.
Additional work at the site was performed to evaluate the
nature and extent of contamination in the soil and groundwater
underneath Tar Lake. The final soil boring and monitoring
well installation work .plan was submitted to U. S. EPA by
Fifty-Sixth Century I s consultant, Ensafe, on september 13,
1989. These most recent investigations provide evidence that
Tar Lake is a continuing source of contamination to the
groundwater at the Site. The depth sounding survey has
revealed that part of Tar Lake is actually 10 feet below the
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3
groundwater table and is over 27 feet in the western part of
Tar Lake. The sampling and analyses have established a
relationship between the tar and the groundwater underneath
Tar Lake. Over 50 identified or tentatively identified
compounds from Tar Lake have been found in the groundwater.
Two substances of note are benzene and styrene. Benzene was
found in the tar at 1.2 parts per million (ppm) and in the
groundwater at 0.43. ppm and 0.04 ppm. These groundwater
concentrations of benzene are above the Safe Drinking Water
Maximum contaminant Level (MCL) of 0.005 ppm. It should be
noted that benzene was found previously in a monitoring well
sampled for the Preliminary Endangerment Assessment but it was
attributed to possible gasoline contamination and was not
addressed further in the PEA. U.S. EPA's position was that
estimated positive values for benzene (as well as for
naphthalene, toluene, ethylbenzene, and xylenes) were found in
other wells also; thus, it was incorrect to dismiss the
significance of the presence of this constituent. Styrene was
also found in the groundwater at levels above its MCL of 0.005
ppm. The concentration of styrene found was 0.006 ppm and an
estimated 0.063 ppm.
The contamination due to the site extends approximately 3.5
miles downgradient from the site as evidenced by taste and
odor observations in groundwater monitoring and residential
wells made by Michigan Department of Natural Resources (MDNR)
staff and the affected residents. Because the tar is a
continuing source of contamination to the groundwater, which
isa threat to the environment as well as a threat to human
health, U.s. EPA determined. that the remediation of Tar Lake
through a source control and groundwater containment operable
unit was appropriate. .
The 1986 Consent Order was amended in August 1990 to have
Fifty-Sixth Century conduct a Phased Feasibility Study (PFS)
to address the operable unit. Fifty-Sixth Century turned in
an unacceptable PFS report to the U.S. EPA, which among other
errors, utilized a risk assessment based on methodology used
in the unapproved Preliminary Endangerment Assessment. Fifty-
sixth Century's revision was also unacceptable, even after
receiving additional time from the Agency to incorporate U.s.
EPA's comments. Therefore, U. S. EPA took over the preparation
of the final PFS Report. U.S. EPA completed the PFS Report in
March 1992, including a risk assessment. The PFS evaluated
seven remedial alternatives to address the source control and
interim groundwater containment at the site.
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4
III. COMMUNITY RELATIONS
As part of the community relations program, an information
repository has been established near the site at the Mancelona
Public Library. The Phased Feasibility study Report, Proposed
Plan, and other site-related materials have been placed in the
repository.
u.s. EPA notified the local. community, by way of the Proposed
Plan, of the preferred remedial alternative for the Tar Lake
site. To encourage public participation in the selection of
a remedial alternative for this operable unit, u.s. EPA
scheduled a public comment period from July 17, 1992 to August
17, 1992. In addition; u.s. EPA held a public meeting on
August 6, 1992 to discuss the Proposed Plan. U. S. EPA' s
responses to comments received during the public meeting and
to written comments received during the public comment period
are included in the Responsiveness Summary.
The public participation requirements of the comprehensive
Environmental Response, compensation, and Liability Act of
1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), sections 113 (k) (2) (8) (i-v)
and 117 have been satisfied.
IV. SCOPE OF RESPONSE ACTION
This operable unit addresses environmental contamination and
public health risks resulting from releases or potential
releases from Tar Lake.
The National oil and Hazardous Substances Pollution
contingency Plan (NCP) is explicit in its stated support of
the "bias for action" approach on Superfund sites. The
"operable unit" is an outgrowth of this concept and is defined
in the NCP section 300.5 as "... discrete action that comprises
an incremental step toward comprehensively addressing site
problems. . . " . U. S. EPA decided that for proper management of
the Tar Lake site in an effort to expeditiously implement Site
remedy for protection of public health and the environment,. an
operable unit was a prudent and appropriate measure to take.
The operable unit addresses two components at the Tar Lake
site. The first component is source control, i.e., the tar
and contaminated soils. The second component concerns an
interim groundwater remedy to prevent further migration of the
contaminant plume.
Source control is addressed by excavating/consolidating the
tar and contaminated soils in and around Tar Lake (soils with
an excess cancer risk level of greater than 1 x 10-6) and
disposing them on-site in two adjoining Resource conservation
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5
and Recovery Act (RCRA) containment cells. The cells shall be
constructed in the area of contamination and shall meet
minimum technology requirements, i.e. double liners, leachate
collection systems, and groundwater monitoring. The tar shall
be solidified with bentonite and cement to enable it to
support the weight of a cap. The containment cells shall be
covered by a RCRA subtitle C hazardous waste cap.
Interim groundwater containment is addressed by pumping and
treating the contaminated groundwater to prevent further
migration of the plume. The treated groundwater shall meet
reinjection standards prior to being reinjected into the
ground. The reinjection location shall be upgradient of the
extraction wells and shall form a closed loop system. This
shall continue until the second operable unit at the site
addresses the final groundwater cleanup. Because the
groundwater containment is an interim measure, groundwater
cleanup standards are waived. Insti tutional controls to
restrict groundwater usage within the areas of the existing or
potential contaminant plume shall be implemented.
There will be a subsequent operable unit which will address
the final groundwater. cleanup. A subsequent Record of
Decision will be issued selecting a groundwater cleanup
remedy.
v. SITE CHARACTERISTICS
Tar Lake, itself, is approximately 4 acres in size and is
located in a topographical depression. Tar was apparently
deposited on the property at the top. of a hill and filled in
low lying areas and gullies. Because of its age, exposure to
air and water, and fire, the tar exists in various. physical
forms, ranging from viscous liquid to semi-solid. Depth of
tar varies from 2 feet to 27 feet, with part of the tar
actually 10 feet below the groundwater table, as shown in
Figures 2 through 4. The tar overlays a soil which is
primarily sand and gravel.
The tar exhibits a strong chemical odor. Groundwater
downgradient of the site also exhibits odors which have been
attributed to the low odor thresholds of site contaminants.
~he Tar Lake site is underlain predominantly by brown medium
sand. There are some thin lenses of silt and clay. The
groundwater table in the unconfined, glacial outwash aquifer
is about 15 to 50 feet below the ground surface. Groundwater
flow is generally in a northwesterly direction with a more
northerly component on the eastern side of the site as shown
in Figure 5. Groundwater contamination extends approximately
3~5 miles downgradient from the site as seen in Figure 6.
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-------
6
A) organic Compound Analyses
The primary investigations of the identity and concentration
of organic compounds associated with the site are as follows:
1983 Colorimetric Analysis for Phenolic Compounds in
Groundwater
Qualitative colorimetric tests detected total phenolic
compound concentrations in on-site monitoring wells at
concentrations ranging from 3 to 64 ug/l.
1988 Contract Laboratorv proaram (CLP) Analysis for Volatile
and Semi-Volatile Compounds in Groundwater
Groundwater samples collected from on-site monitoring wells
(MW-6, MW-7, MW-11, MW-12, MW-13, MW-14, MW-15, MW-16) (see
Figure 7) were analyzed for volatile and semi-volatile
compounds contained in the CLP Target Compound List. Results
of these analyses indicated 'the presence in downgradient wells
of three compounds at concentrations exceeding the Contract
Required Quantitation Limits: 2, 4-dimethylphenol (57-59 ug/ 1) ,
ethylbenzene (7 ug/l), and total xylenes (7 ug/l). Other
compounds tentatively identified in on-site wells included
phenols, ketones, alcohols, and esters. concentrations for
the positively identified compounds are summarized in Table 1-
1988 Special Protocol Analysis for Phenols in Groundwater
sampling and special protocol analysis of, 28 area wells,
predominantly off-site (see Figure 8) suggested the presence
of a number of alkylphenols in downgradient groundwater. No
given alkylphenol was present at concentrations exceeding the
quantitation limit for the analysis, 0.8 ug/l.
The exact str" ::ure of indi - idual compounds detected using the
special prot__:Jl analysi~ .;ould not be determined, rather
alkylphenols were identified by the number of carbon atoms in
substituents on the aromatic ring. For example, a compound
was identified generally as a C-2 alkylphenol (an alkylphenol
bearing sUDstituent(s) containing 2 carbon atoms) which might
be either 2,3-, 2,4-, 2,5-, or 3,4-dimethylphenol or 2-, 3-,
or 4-ethylphenol. C-2 through C-12 alkylphenols were
detected. Given the nature of the available data from the
special protocol analysis, a list of compounds. that could
concei vable be present in the groundwater was prepared '-Y
Ensafe using CRC Handbook of Chemistrv and Phvsics, 68th
edition, 1987, CRC Press, Boca Raton FL, to obtain a list of
those known compounds meeting the criteria of C-2 through C-12
alkylphenols. These compounds are listed in Table 2.
1989 CLP Analysis for Volatile and Semi-Volatile Compounds in
Tar. Soil. and Groundwater
samples of tar from Tar Lake, soil immediately beneath the
tar, and groundwater immediately beneath the tar were
-------
fIGURE 7
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-------
TABLE 1 - Positively Identified compounds in Groundwater
comDound
VOLATILES:
Chloroform
Benzene
Toluene
Ethylbenzene
Xylenes
SEMI-VOLATILES:
4-methyl phenol
Nitrobenzene
2,4-dimethyl-
phenol
Naphthalene
MW-6
CONCENTRATION (ugfl)
MW-7 MW-11(1) MW-12 MW-13
Detect
Limit
MW-14 (1)
MW-15
MW-16
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3 J
7
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5 J
57 59
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20
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J - compound was detected at a concentration below the quantitation limit reporte
concentrations are estimated values.
A blank indicates that the compound was tested for but not detected. Only thos
compounds detected ~n at least one sample are listed. Chloroform was detected i.
a field blank.
NOTES:
(1) Sample analyzed in duplicate.
reported.
Values are averaged and all qualifiers ar;
Adapted from Table 1-1, unapproved Phased Feasibility Study, Tar Lake Superfunc
Site, :;radient C::n -ati-:1, February 12,. -:'91.
-------
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-------
TABLE 2 - C-2 Through C-12 Alkylphenols
C-2 Alkvlphenols
2,3-dimethyl phenol
2,4-dimethyl phenol
2,S-dimethyl phenol
2,6-dimethyl phenol
3,4-dimethyl phenol
3,S-dimethyl phenol
2-ethyl phenol
3-ethyl phenol
4-ethyl phenol
C-3 AlkVlphen'ols
2-propyl phenol
3-propyl phenol
4-propyl phenol
2-isopropyl phenol
3-isopropyl phenol
4-isopropyl phenol
2,4,S-trimethyl phenol
2,4,6-trimethyl phenol
C-4 Alkvlphenols
2,3,4,S-tetramethyl phenol
2,3,4,6-tetramethyl phenol
2,3,S,6-tetramethyl phenol
2-methyl,S-isopropyl phenol
4-tert-butyl phenol
4-sec-butyl phenol
4-butyl phenol
3-tert-butyl phenol
3 -butyl phenol.
2-tert-butyl ?henol
2-sec-butyl phenol
2-butyl phenol
C-B Alkvlphenols
2,4-di-tert-butyl phenol
2,6-di-tert-butyl phenol
2,6-di-sec-butyl phenol
2-octyl phenol
C-9 Alkvlphenols
2,4-di-tert-butyl-S-methyl
2,4-di-tert-butyl-6-methyl
2,6-di-tert-butyl-4-methyl
phenol
phenol
phenol
C-10 - C-12 Alkvlphenols
2,6-di-tert-butyl-4-ethyl phenol
2,6-{bis) (l,l-dimethyl propyl)-
4-methyl phenol
2,4,6-tri-tert-butyl phenol
Adapted from Tabie 1-2, unapproved Phased Feasibility study, Tar Lake
Superfund Site, Gradient Corporation, February 12, 1991
-------
7
collected from the locations shown in Figure 9 and analyzed
for volatile and semi-volatile compounds contained in the U. s..
EPA CLP Target Compound List.
The highest concentration of organic compounds detected in tar
from Tar Lake were alkylphenols (1,100 to 2,000 mgjkg). Other
classes of organic compounds detected in the tar included:
Benzene (1.2 mgjkg), Ethylbenzene (100 mgjkg), Toluene (100
mgjkg), styrene (2.3 mgjkg),other polynuclear aromatic
hydrocarbons (100 to 560 mgjkg), monoaromatic hydrocarbons (5
to 280 mgjkg) and ketones (1.2 to 15 mgjkg). A similar array
of compounds' was detected in soil samples collected
immediately beneath Tar Lake at concentrations between 1 and
25% of the concentrations measured in the tar.
Groundwater samples contained the more water soluble of the
organic constituents detected in the tar (i.e. alkylphenols,
monoaromatic hydrocarbons, and ketones). concentrations .of
these compounds were lower than the soil concentrations,
roughly 0.01 to 1% of the concentration measured in the tar.
Benzene (0.4-0.43 ppm) and styrene (0.006-0.063 ppm) were both
present in the groundwater at concentrations which exceed the
Safe Drinking Water Act Maximum contaminant Levels (MCLs),
0.005 ppm for benzene and 0.006 ppm for styrene. Naphthalene
(ranging between not detectable and 0.038 ppm) and 2-
methylnaphthalene (0.017-0.38 ppm) were present in the
groundwater.
Concentration data for all of the CLP Target Compound List
chemicals detected during this analysis are summarized in
Table 3.
The contamination due to the site extends approximately 3.5
miles downgradient from the site as evidenced by taste and
odor observations in monitored wells by the Michigan
Department of Natural Resources (MDNR) staff and the affected
residents. The organic compound data collected to date
indicates the existence of a steep concentration gradient with
distance from Tar Lake. While there is a taste and odor
problem in downgradient wells, analyses of samples collected
show that the contaminants are below the detection limits.
This. is due to the low taste and odor thresholds for the site
contaminants.
B) Inorganic compound Analyses
The primary investigations of the identity and concentration
of inorganic compounds associated with the site are as
follows:
-------
?IGUTIE 9
3aoplla; I...ocations on Tar L::.l~e
--"
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80
WAtER
TAR UICE
-.,..m)RING WELLLOCA'I1ON
LYS8IEt'ER LOCAt1ON
o
so
,.
.
SCAUi It F&:T
SAMPUNG LOCATIONS:
I
Samole
Location
~
B2.O%I"AR MW-202
lOft beJaw lake surface
B20tA
B201B
201
MW-201
MW-201
MW-201
13 ft below lake surface; 4 ft beiow tar
15 ft below lake swtaa:; 6 ft beiow Iar
sc:reeacd 16 ft beiow ~ 7 ft below tar
rrOr:l Figure 1, 1989 Antrio. Iron Harks (Tar
B202A MW-202 15 ft below lake surface; < 1 ft beiow tar
B202B MW-202 17 ft betow late surtac:c; 3 ft belOw Iar
B202C MW-202 19 ft below late surface; 4 ft belOw tar
202 MW.202 sc:reeacd 20 ft beJow lake surface; S ft below tar
L~ce) Site Investigation, Vol. I, Gradient Corp., 3/
-------
TABLI~ 3 Cor.\pollndn Dctccted in Tar, Sili I ~, and Grollnd\lfJter at TiJr I.dlu ~
COMI'OIiNU H!! ~1~!!lt: fmKlKlt SOli- SA~!!'! .!::." . III!;!!' 1il--. \V A'f~U SAM !1!~J!!!Ii!!:! -
111 IT
olon III IIIOIA III IIIUI JlIII IIIOIA IIIO!II IUOIC III 101111 101 III
vOlAIlJ.l!5:
IIcnunc 1.2 II II) I 21 11.0 11111
I!lhylbcnune IUO 11 14 111112 lUlU I J 011 IIIIH
lilluene UKI 41 1(1 11.(101 J tlIIIS 0001 J 062 II 16
Slrrcnc 2.1 I ) 28 1111111 ) 0.11(1) !lIKI6
HhJlaliooc S Ii 1112 0.211 II tUb 11111 IIIH)) J 1.'.1 11111 S
2. II Ckanone II I! 06) J 2.4 001) II If! 1 II ~II
4. MClhyl.2-pcnlllnune 1.1 111111 UlIll 0.'191
Xylenes (1IiIal) 2110 I: IJ' 11 (l1HI2 J III"'" II IHI1 II]') 1111'
~C:MI.vOl.AIU.I:S:
Ac:enllj1lhcnc ) 1 J 11111 J
Acenaplllyle,..c 4! J 1\ I II 14 I nlWJ
Anlh,aocne U I II J II I II 1
lIen1O( a )anatu aune 2) J 1111(,] I
IIcnW( b IOuOf.nlhcnc n18 JX
IIcnw(~ IRuorlnlhcne II 1ft IX
bis.(2.I!Illylhc ryl)phl halale UOII] J II 111111 J 11011 J !lIKII
Chl)'$Cnc I ~ ) 0 1114 I
l>i.n.bul)1 phlhahllC IIIIIU I II 2U I
nUOlillllhcnc I c. I 111\ I
. numene IIMI H J 111114 J 11\1 II m'J ) III MI~
Hafllhalcnc )411 \ I II,U 1111(, 1 J 1 1 liD J UIlIIi
"hcnuOIh,ene I') -III I 11(1)') I Ulii, IIlkll
"y,ene 1 2 ) 14 I 112/ I
lJitlCnlllluliin ~I 14 H I II i, \I II J'J I III H II
2. MClhylnaphlhillcnc ~(.cl ~'I 1211 UII/I J IIi 1114 J II)/j 11111/
2." .Dimel hY'phcnoi 201111 1111 i, III 'Ii 11 I ~ 29 II
I' h( 11111 rill H I!II I I II II ~'I'
2.Mclh)'lphtUIiI 111111 I~II ~IIII IIII~ 1 J ! I 111 II III
~-MC1h)lflhcnll' 141111 1111 10'111 (. I! II \ I 4') .1'1
.-.. -- --. ------...-
Adapted fron 'i'able 1-3, I1napproved Pllil::p.d Femd hi! it Y St110Y, 'i'ar L:!w SlIp0.Lfl1m1 SHe. r.radient c.orp., F~h. Ii.) I CJI))
-------
8
1988 CLP Analvsis for Metals in Groundwater
Groundwater samples collected from on-site monitoring wells
(MW-S, MW-7, MW-11, MW-12, MW-13, MW-14, MW-1S, and MW-16;
Figure 1) were analyzed for metals contained in the CLP Target
Compound List. Results of these analyses indicated that metal
concentrations in groundwater downgradient of Tar Lake are
comparable to background levels.
1989 CLP Analvsis for Metals in Groundwater
Samples of tar from Tar Lake, soil immediately beneath the
tar, and groundwater immediately beneath the tar were
collected from the locations shown in Figure 3 and analyzed
for metals contained in the EPA CLP Target Compound List.
These results indicated that metal concentrations in
groundwater are below MCLs and that metal levels in soil are
comparable to background concentrations.
The inorganic data collected to date indicate a negligible
impact of Tar Lake on local metal concentrations.
VI. SUMMARY OF SITE RISK
As part of the PFS, a baseline risk assessment was performed
by the Region V Office of Health and Environmental Assessment.
The risk assessment focused on a few of the most critical
potential exposure pathways for the Tar Lake operable unit.
Exposure scenarios were chosen and evaluated in accordance
with current u.S. EPA guidance, Risk Assessment Guidance for
SUDerfund. Volume 1. Human Health Evaluation Manual (Part A) .
Interim Final, EPA/540/1-89/002.
By definition, a baseline risk assessment is limited to.
conditions assuming no corrective action will take place and
no site-use restrictions or institutional controls will be
imposed. The risk assessment determines actual or potential
risks or toxic effects posed by the chemical contaminants ,t
the site under current and future use assumptions.
A) Identification of Chemicals of Potential Concern
On-site groundwater sampling was conducted in 1988 and 1989.
Contaminant concentration values fro'!! the associated analyses,
mean1d 95% upper confidence ~it, were utilized in
assess_ngOrisk from groundwater. ~ number of chemicals of
concern were detected including phenol, o-cresol, p-cresol,
and benzene. The list of groundwater chemicals and
concentrations are found in Table 4.
-------
TABLE 4 - COMPOUNDS DETECTED IN ON-SITE GROUNDWATER
COMPOUND
MEAN CONCENTRATION
( ua 11 )
95TH PERCENTILE
OF MEAN CONCENTRATION
(ua 11)
Benzene
Ethylbenzene
Toluene
styrene
2-Butanone
2-Hexanone
4-Methyl-2-Pentanone
Xylenes
49.2
18.95
80.05
8.9
195.5
95.5
13.6
55.45
115.7
37.7
177.1
18.3
492.0
237.2
27.1
117.4
Acenaphthylene
BiS(2-ethylhexyl)phthalate
Fluorene
Naphthalene
Phenanthrene
oibenzofuran
2-Methylnaphthalene
2,4-Dimethylphenol
Phenol
2-Methylphenol
4-Methylphenol
>litrobenzene
13.9
7.9
9.5
10.7
9.4
9.4
47.7
3228.0
1437.0
2886.0
5397.0
9.5
20.0
9.6
10.3
15.7
10.3
10.3
105.5
7736.0
3622.5
7255.6
13019.0
10.3
Adapted from Table B2a, unapproved Phased Feasibility study, Tar Lake Superfun
site, Gradient corporation, February 12, 1991.
-------
9
Despite the volume and heterogenous nature of Tar Lake, only
one tar sample was collected. certain polycyclic aromatic
hydrocarbons (PAHs) detected in the underlying soil were
assumed to be present in the tar at the detection limit (280
mg/kg). This is a reasonable assumption since the compounds
were detected in the soil beneath the tar. A number of other
compounds were detected including phenols, o-cresol, p-cresol,
and 2, 4-dimethylphenol. A list of chemicals detected or
presumed to be present in the tar is listed in Table 5, along
with their concentrations.
B) Exposure Assessment
Two hypothetical future residential exposure pathways were
evaluated. In the first, it was assumed that future residents
might be chronically exposed to groundwater through ingestion
of drinking water. standard u.s. EPA assumptions for
Superfund were utilized (2 liters of water ingested per day
for 30 years by a 70 kg individual). In the second pathway,
exposure of future residents through soil was assessed. This
assumed the placement of a house adjacent to Tar Lake such
that soil concentrations of contaminants equal one-tenth the
concentrations present in the tar itself. In accordance with
current Superfund guidance, individuals were assumed to ingest
0.100 grams of soil per day in the form of some combination of
soil and dust. This exposure was presumed to take place 350
days per year for 30 years. This exposure analysis did not
include a separate analysis for exposure to children, due to
the uncertainty in the data. If children were included in the
analysis, the overall exposure and risks would be even
greater.
In addressing the soil and groundwater ingestion for future
residents, the risk assessment characterizes two of the most
significant pathways. However, these are only two of many
exposure pathways which are pertinent at this site. other
potentially significant exposure routes include soil and
groundwater ingestion for future workers, soil ingestion for
trespassers, dermal contact for residents, workers, and
trespassers, and ingestion of contaminated game.
C) Risk Characterization
The risk assessment characterizes the most serious risks by
assessing ingestion of groundwater and soil using a
hypothetical future risk scenario. (See Table 6)
Significant non-cancer risks exist at the site via the
groundwater pathway, both when considering mean groundwater
concentrations on-site and, more appropriately, when
-------
TABLE 5 - COMPOUNDS KNOWN OR PRESUMED TO BE IN TAR
COMPOUND
CONCENTRATION
(ma/ka)
Benzene
Ethylbenzene
Toluene
styrene
2-Butanone
2-Hexanone
4-Methyl-2-Pentanone
Xylenes (total)
1.2
100
100
2.3
5
11
1.2
280
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a} anthracene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Bis (2-ethylhexyl) phthalate
Chrysene
Di-n-butyl phthalate
F1uoranthene
Fluorene
Naphthalene
Phenanthrene
pyrene
Dibenzofuran
2-Methylnaphthalene
2,4-Dimethylphenol
Phenol
2-Methylphenol
4-Methylphenol
280
280
280
280
280
280
280
280
280
280
100
340
280
280
51
560
2000
330
1100
1400
Adapted from Table B4a, unapproved Phased Feasibility study for Tar
Lake, Gradient corporation, February 12, 1991.
-------
TABLE 6 - Cancer Risk and Non-cancer Hazard
for Tar Lake
Future Residential scenario
( 1)
EXPOSURE PATHWAY
CANCER RISK
HAZARD INDEX
ACUTE HAZARD
Ingestion of
Groundwater
(95% UCL)
4.8 X 10.5
24
Not Assessed
Ingestion of
Tar-contaminated
8.0 X 10.4
0.03
High (2)
(1) Values listed in this table were obtained from the output of
the RISK ASSISTANT program.
(2) Potential for acute health effects from exposure to tar was
judged to be high, based on high concentrations of phenols and
cresols, reports of chemical burns and skin irritation and
potentially lethal depth and viscosity of the tar.
-------
10
considering the 95% upper confidence limit on the arithmetic
mean of the data (95% UCL). Hazard Indices equal
approximately 11 and 24-, respectively. The cancer risk from
ingestion - of groundwater, as part of the same residential
scenario, is 2.4 X 10-5 and 4.8 X 10-5 for mean and 95% UCL
respectively.
The tar poses cancer risk due to the presence of polycyclic
aromatic hydrocarbons (PAHs). There are numerous sources of
uncertainty due to the limited data available in the cancer
analysis. The tar is described as being very heterogenous in
viscosity,and appearance. This risk assessment utilized the
-assumption that a number of PAHs were present in the tar at
the limit of detection. This assumption is reasonable since
the PAHs assumed to be present in the tar were detected in the
soil beneath the tar. Use of surrogate values in a
residential scenario results in a cancer risk driven by PARs
as high as 8 x 10-4, assuming chronic exposure to soil
containing contaminants at one tenth the detection limit in
the tar.
A number of compounds present in the tar could present severe
acute health risks if ingested or absorbed through the skin,
especiall.y phenol. The viscosity of the tar alone presents an
extreme hazard. Adolescents or others who manage to trespass
on the site could easily fall into the tar and perish.
The cancer risk at Tar Lake (8 X 10.4) exceeds the 1 x 10'4
level which warrants remedial action under U.s. EPA policy,
OSWER Directive 9355.0-30. It also exceeds the acceptable
exposure levels for known or suspected carcinogens of 1 x 10.4
to 1 X 10.6 as presented-in Section 300.430(e) (2) (i) (A) (2) of
the NCP. The non-carcinogenic risk at Tar Lake (hazard index
= 24) exceeds the level at which no adverse health effects can
be expected (hazard index> 1). These facts, along with
excedences of - MCLs in the on-site groundwater and the
continuing contamination of the groundwater by the source,
warrant an action at the Tar Lake Site. .
D) Environmental Risks
In addition to the human health risks at the site, there are
risks to the environment. The tar is 10 feet below the water
table contaminating the groundwater, with effects observed 3.5
miles downgradient from the site. Because of the viscosity
and depth of the tar, it poses a serious hazard to wildlife in
the area. Waterfowl can be attracted to the liquid surface
and can either become stuck in the tar and- perish there, or
may escape covered with the oily mixture, which could also be
lethal. Small animals in the area also are vulnerable to the
same threat of sinking into the tar.
-------
11
VII. CLEANUP STANDARDS
The remedial action cleanup standards, upon which the volume
of the contaminated soil excavation/consolidation are based,
comply with Michigan Environmental Response Act (Act 307) Type
B cleanup criteria and are as follows in Table 7:
TABLE 7 - SOIL CLEANUP STANDARDS
Chemical
Soil criteria (ppb) *
CARCINOGENS
Benzene
Styrene
Benzo(a) anthracene
Benzo (b) fluoranthene .
Benzo(k)fluoranthene
Chrysene
0.4
20
100
100
100
100
NON-CARCINOGENS
Ethylbenzene
Toluene
2-Butanone
4-Methyl-2-Pentanone
Xylenes
Acenapthene
Anthracene
Di-n-butyl phthalate
Fluoranthene
Fluorene.
Naphthalene
pyrene
2,4-Dimethylphenol
Phenol
2-Methylphenol
4-Methylphenol
1,400
16,000
7,000
7,000
6,000
2,000
40,000
14,000
6,000
6,000
800
4,000
8,000
6,000
8,000
8,000
* If U.s. EPA determines that local background is greater than
these health-based criteria, the average local background can be
used as a final cleanup goal.
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The reinjection of the treated groundwater that is discharged
from the groundwater containment system shall meet reinj ection
standards that will be determined by U.S. EPA, in consultation
with MDNR. These reinjection standards will meet Michigan
Environmental Response Act (Act 307) Type B levels and is
deemed to meet Part 22 of the Michigan Water Resources Act
(Act 245). A closed loop system shall be formed by
reinjecting the treated water upgradient" of the extraction
wells. '
VIII.DESCRIPTION OF ALTERNATIVES
The following is a short discussion of each of the remedial
action alternatives that were analyzed in detail in the PFS.
More precise volumes of tar and contaminated soils, as well as
the additional concentration data, will be gathered during the
pre-design phase of the remedial design. The exact extent of
the contaminated soils may have to be determined after the tar
has been removed. The following assumptions were used for
each of the alternatives:
The volume of tar present is estimated to be 30,000 cubic
yards. A minimum quantity of 20,000 cubic yards of tar
was calculated in a depth sounding survey. The 30,000
cubic yards includes a 50% uncertainty factor because it
is believed that there is additional tar on the western
and southern sides of Tar Lake.
The volume of highly contaminated soils (excess cancer
risk greater than or equal to 1 X 10-2) is estimated to
be 20,000 cubic yards.
The volume of low level contaminated soils (excess cancer
risk less than 1 x 10-2 and greater than 1 x 10-°) is
20,000 cubic yards.
The tar waste is very similar to RCRA K087 waste, Le.,
decanter tank tar sludge from coking operations, and contains
many of the same hazardous compounds. Therefore, the tar and
contaminated soils shall be handled as a hazardous waste.
Seven alternatives were evaluated for the source control and
groundwater containment operable unit at Tar Lake.
ALTERNATIVE 1 - NO ACTION
CERCLA requires that a "no action" alternative be considered
at every. site. Under this alternative, no further action
would be taken at the Tar Lake site to reduce risks or to
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control the source and migration of contaminants. The no
action al ternati ve will not modify the si te in any way.
Alternative 1 has no cost.
ALTERHAT:IVE 2 - REKOVAL AND INCINERATION OF TAR AND HIGHLY
CONTAKIHATED SOILS; BIO-REHEDIATION AND CONTAINKEN'l'
OF REHAIHING SOILS; INTERIM GROUNDWATER CONTAINKEN'l'
This alternative involves the excavation and incineration on-
site of the tar and the highly contaminated soils (soils with
an excess cancer risk level greater than or equal to 1 x 10-')
in and around Tar Lake extending to the adjacent landfill. To
facilitate the excavation of the tar and soils, a dewatering
system would be constructed. The exact number and placement
of dewatering extraction wells would depend on the areal
extent and depth of contamination, and would be. determined as
part of the Remedial Design. The excavation would require the
use of conventional equipment including drag-lines, conveyor
loaders, backhoes, and bulldozers.
The incineration technologies available and considered
appropriate to incinerate the tar and soils include rotary
kiln and infrared. The rotary kiln uses a primary combustion
chamber heated by a natural gas or fuel oil burner. For
material like the tar, the waste. itself can sometimes be used
to substitute for the natural gas jr fuel oil. The infrared
incinerators use infrared energy t- heat the waste material in
the presence of air until the auto-ignition temperature is
reached. The tar and contaminated soils would be incinerated
separately. contaminated soil is not a waste, but only a
media containing waste. Thus, the incinerated (treated) soil
would be considered clean when the contamination is reduced
below health based levels and would no longer need to be
managed as a hazardous waste. It could be used as backfill at
the site. Ash and any residue resulting from the incineration
of the tar remains a listed waste and would be treated and
disposed of in a licensed hazardous waste facility.
The remaining soil with an excess cancer risk level less th~n
1 x 10-2 and greater than 1 x 10 -6 (approximately 20,000 yd,)}
would be bio-remediated in-situ to the maximum extent
practicable with the goal being Michigan Act 307 Type B
levels. The treated soil would be contained on-site with the
installation of hazardous waste cap that meets RCRA subtitle
C and Michigan Act 64 requirements if it is determined that
bio-remediation can not reach the desired cleanup goal. The
bio-remediation involves the addition of nutrients and oxygen
to the media to promote biO-degradation of contaminants by
microorganisms. The exact amenability to this technology
would be determined in pre-design treatability studies.
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An interim groundwat~r containment system would be installed
to prevent the contaminant plume from migrating further. This
containment system would be constructed prior to any
excavation work performed on the tar and contaminated soils so
that any possible contaminant releases to the groundwater
would be captured and the dewatering system discharge can be
treated. This includes:
- Installation of a groundwater pump and treat system for
the containment of contaminated groundwater, the
treatment of water ponded on Tar Lake, and discharge from
the dewatering system
- Implementation of institutional controls including but not
limited to, deed restrictions regulating the development of
the Tar Lake property and groundwater usage restrictions
within the areas of the existing or potential contaminant
plume.
The groundwater pump and treat component would consist of: 1)
a series of extraction wells at the down-gradient edge of the
Tar Lake property to prevent further migration of the
contaminant plume, and 2) an appropriate treatment system on-
site, possibly carbon absorption, to treat the contaminated
groundwater, water ponded on Tar Lake, and discharge from the
dewatering system. Discharge from the treatment system would
be required to meet applicable effluent discharge limitations
as determined ~y u.s. EPA, in consultation with MDNR.
Residues from the treatment system which contain constituents
of K087 must be managed as hazardous waste. Because there is
no surface water body or POTW nearby, the treated groundwater
would be reinjected into the ground upgradient of the
extraction wells forming a closed loop system. The reinjected
groundwater will meet the substanti ve requirements under
Michigan Act 307 and Michigan Act 245 Part 22. This could be
used in conjunction with the bio-remediation of the lowly
contaminated soils. The discharged water could be
supplemented with the necessary nutrients for the bio-
remediation process. Existing groundwater monitoring wells
would be used to monitor the effectiveness of the groundwater
containment system. Wells would be sampled on a monthly basis
to ensure that exposure to contaminants does. not occur.
Because the groundwater containment is an interim measure,
groundwater cleanup standards are waived. Final remedy for
the groundwater, including the establishment of clean-up
standards, will be addressed in the second operable unit.
Water use restrictions and institutional controls to restrict
groundwater usage within the areas of the existing or
potential contaminant plume would be implemented.
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A site evaluation would be performed every five years for a 30
year period. The purpose of this evaluation would be to
determine if site conditions are changing, and if so, what
actions may be necessary to address these changes.
Alternative 2 has an estimated capital cost of $47.6 million.
and an estimated annual operation and maintenance cost of $
$874,800. The estimated present worth cost is $51.4 million.
ALTERJlATIVE 3 - REMOVAL AND INCINERATION OF TAR AND HIGHLY
CON'l'AHINATED SOILS; DISPOSAL OF THE REMAINING SOILS AT AN
APPROVED HAZARDOUS WASTE LANDFILL; INTERIM GROUNDWATER
CON'l'AIHHENT .
This alternative involves the excavation and on-site
incineration of the tar and the highly ""~ntaminated soils
(soils with an excess cancer risk level grcer than or equal
to 1 x 10-2) in and around Tar Lake extend1ng to the adjacent
landfill as explained in Alternative 2. .
The remaining soil with an excess cancer risk level of less
than 1 x 10-2 and greater than 1 x 10-6 (approximately 20,000
yd3) would be excavated and disposed of at a licensed
hazardous waste landfill. The soils must first meet alternate
treatment standards under a treatability var'iance from RCRA
Land Disposal Restrictions (LDRs). The levels would be
determined during pre-design. If the alternate treatment
levels are above health based levels, the soils would be
loaded onto trucks and transported to a hazardous waste
landfill. If the treatment levels are below health based
levels, the soil could be backfilled at the site.
At the completion of the excavation, depressions caused by the
excavations would be backfilled with clean soil to the
original grade, covered with topsoil and revegetated to
prevent erosion.
As in Alternative 2, an interim groundwater containment system
would be installed to keep the contaminant plume from
migrating further. (The addition of nutrients to aide bio-
remediation as described in Alternative 2 is not applicable to
this alternative.) Because the groundwater containment is an
interim measure, groundwater cleanup standards are waived.
Final remedy for the groundwater, including clean-up
standards, will be addressed in the second operable unit.
Alternative 3 has an estimated capital cost of $55.1 million
and an estimated annual operation and maintenance cost of
$791,800. The estimated present worth cost is $58.5 million.
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ALTERNATIVE 4 - REMOVAL AND INCINERATION OF TAR AND HIGHLY
CONTAMINATED SOILS; THERMALLY TREAT REMAINING SOILS; INTERIM
GROUNDWATER CONTAINMENT
This alternative involves the excavation and on-site
incineration of the tar and the highly contaminated soils
(soils with an excess cancer risk level" greater than or equal
to 1 x 10-2) in and around Tar Lake extending to the adjacent
landfill, as described in detail in Alternative 2.
The remaining soil with an excess cancer risk level of less
than 1 x 10-2 (approximately 20,000 yd3) will be treated
through the use of thermal desorption, with the cleanup goal
being Michigan Act 307 Type B levels. Treatability studies
would be performed during the pre~design to determine the
effectiveness of this treatment technology to the site media
and contaminants. This process physically separates volatile
and some semi-volatile contaminants from soil by heating the
contaminated media between 200 - 1000 degrees F. Offgases may
be burned in an afterburner, condensed to reduce the volume to
be disposed, or captured by carbon adsorption beds. Gaseous
discharges would meet the applicable air discharge limitations
as determined by u.s. EPA, in consultation with MDNR. Any ash
and residue resulting from the process would be treated and
"disposed of appropriately in a permitted facility. If the
soils can be treated below health based levels through thermal
desorption, the soils no longer contains a hazardous waste and
no lonqer needs to be managed as such. If health based levels
are not attained by low temperature thermal desorption, then
RCRA treatment standards must be met and the treatment residue
must be disposed in a RCRA subtitle C unit.
At the completion of the excavation and treatment, depressions
caused by the excavations would be backfilled with clean soil
to the original grade, covered with topsoil and revegetated to
prevent erosion.
As in Alternative 2, an interim groundwater containment system
would be installed to keep the contaminant plume from
migrating further. (The addition of nutrients to aide bio-
remediation as described in Al ternati ve 2 is not applicable to
this alternative.) Because the groundwater containment is an
interim. measure, groundwater cleanup standards are waived.
Final remedy for the groundwater, including the establishment
of clean-up standards, will be addressed in the second
operable unit.
Alternative 4 has an estimated capital cost of $60.8 million
and an estimated annual operation and maintenance cost of
$791,800. The estimated present worth cost is $64.2 million.
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ALTERNATIVE S - REMOVAL AND DISPOSAL OF TAR AND CONTAMINATED
SOILS :IN A HAZARDOUS WASTE LANDF:ILL; INTER:IM GROUNDWATER
CONTAINHEN'l' .
This Alternative involves the excavation and disposal of the
tar and all of the contaminated soils in and around Tar Lake
extending to the adjacent landfill at a licensed hazardous
waste landfill. To facilitate the excavation of the tar and
soils, a dewatering system would be constructed. The exact
number and placement of dewatering extraction wells would
depend on the areal extent and depth of contamination, and
would be determined as part of the Remedial Design. The
excavation would require the use of conventional equipment
including drag-lines, conveyor loaders, backhoes, and
bulldozers.
Once excavated, the tar and contaminated soils would be
treated in order to meet the treatment standards for K087 due
to the similarity of the tar waste to K087 waste, Le.,
decanter tank tar sludge from coking operations, and contains
many of the same hazardous constituents. Since the treatment
standards for K087 are based on incineration, incineration is
the likely treatment required to meet these standards. The
treatment method ultimately used would be determined during
the pre-design phase. The tars and the contaminated soils
would be sampled and treated separately to the maximum extent
possible to avoid diluting the tar in the process. For the
soil, alternate treatment levels under a treatability variance
would be based on data from actual treatment of the soil;
this would be established during the pre-design with the most
appropriate treatment technology.
Once treated, the tar residue would be loaded onto trucks for
transportation to a secure, CERCLA off-site policy compliant,
RCRA Subtitle C facility for disposal. If the treated soil is
below health based levels, it would be considered clean.
contaminated soil is not a waste, but only a media containing
waste. When the contaminants have been removed below health
based levels, the soil no longer contains the waste and no
longer needs to be treated as a hazardous waste. Thus, this
clean soil could be used as backfill at the site.
At the completion of the excavation, depressions caused by the
excavations would be backfilled with clean soil to the
original grade, covered with topsoil and revegetated to
prevent erosion.
As in Al ternati ve 2, an interim groundwater containment system
would be installed to keep the contaminant plume from
migrating further. (The addition of nutrients to aide bio-
remediation as described in Alternative 2 is not applicable to
this alternative.) Because the groundwater containment is an
interim measure, groundwater cleanup standards are waived.
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Final remedy for the groundwater, including the establishment
of clean-up standards, will be addressed in the second
operable unit.
Alternative 5 has an estimated capital cost of $48.9 million
and an estimated annual operation and maintenance cost of
$791,800. The estimated present worth cost is $52.3 million.
ALTElUIATIVE 6 - REMOVAL AND CONSOLIDAT:ION OF TAR AND
CON'l'AK:IHATED SO:ILS IN ON-SITE RCRA CELLS; IN'l'ER:IH
GROUNDWATER CON'l'A:INHEN'l'
This Alternative involves excavating/consolidating the tar and
all of the contaminated soils in and around Tar Lake extending
to the adjacent landfill. Additional sampling would be
conducted during the pre-design to define the limits of
contamination. To facilitate the excavation/consolidation of
the tar and soils, a dewatering system would be constructed.
. The exact number and placement of extraction wells would
depend on the areal extent and depth of contamination, and
would be determined as part of the Remedial Design. The
excavation I consolidation would require the use of conventional
equipment including drag-lines and bulldozers.
The tar and contaminated soils would be contained (untreated)
on-site in two adjoining RCRA containment cells that would be
constructed within the area of contamination. with the
construction of the containment cells within the AOC and
transferring the tar and contaminated soil into the cells
without moving it outside of the AOC or placing it into a
separate unit, placement as defined by RCRA would not occur
and RCRA Land Disposal Restriction (LDR) treatment standards
would not be triggered. This avoids the necessity of having
to incinerate the tar and soils in order to meet the K087
treatment standards. The RCRA cells must meet minimum
technology requirements, i. e. double liners, two leachate
collection systems, and groundwater monitoring. u.s. EPA's
Superfund Technical Assistance Response Team (START) has
conducted tests on the physical capability of the tar to
support the weight of a landfill cover. The results of the
tests indicate that by adding solidification agents (17.5
percent bentonite and 35 percent cement) to the tar, it would
be able to physically support a landfill cover. Final
percentages of solidification agents to be added to the tar
would be determined in the remedial design. The first RCRA
cell will be sized to hold the 30,000 yd3 of tar and
solidification agents. The second RCRA cell would be sized to
hold the contaminated soils . Initial design of the cells
would be based on the estimate of 40,000 yd3 of contaminated
soils. The two cells will be constructed sequentially.
First, the RCRA cell for the tar would be constructed so that
the tar could be excavated and additional sampling can be
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performed on the soils underneath to better determine the
extent of contaminated soils. Once the volume of contaminated
soils is known, final sizing and construction of the second
RCRA cell would be completed. Both cells will be closed with
RCRA subtitle C hazardous waste landfill covers.
As described in Alternative 2, an interim groundwater
containment system would be installed to keep the contaminant
plume from migrating further. (The addition of nutrients to
aide bio-remediation as described in Alternative 2 is not
applicable to this alternative.) Because the groundwater
containment is an interim measure, groundwater cleanup
standards are. waived. Final remedy for the. groundwater,
including the establishment of clean-up standards, will be
addressed in the second operable unit.
Alternative 6 has an estimated capital cost of $16.7 million
and an estimated annual operation and maintenance cost of
$791,800. The estimated present worth cost is $20.1 million.
ALTERNATIVE 7 - REMOVAL AND DISPOSAL OF TAR AND HIGHLY
CONTAKI~TED SOILS IN AN OFP-SITE HAZARDOUS WASTE LANDFILL;
BIO-RBHEDIATION OP LOW LEVEL SOILS AND COHTAIHHEHT; INTERIM
GROtJHDWATER COHTAINHEH'l'
This Alternative involves excavating the tar and the highly
contaminated soils in and around Tar Lake extending to the
adjacent landfill. Additional sampling would be conducted
during the pre-design phase to define the limits of
contamination. To facilitate the excavation of the tar and
soils, a dewatering system would be constructed. The exact
number and placement of extraction wells would depend on the
areal extent and depth of contamination, and would be
determined as a part of the Remedial Design. The excavation
would require the use of conventional equipment including
drag-lines, conveyor loaders, backhoes, and bulldozers.
Once excavated the tar and highly contaminated soils would be
treated in order to meet the treatment standards for K087
because the tar waste is very similar to K087 waste, i.e.,
decanter tank tar sludge from coking operations, and contains
many of the same hazardous constituents. since the treatment
standards for K087 are based on incineration, incineration
would likely be required to meet these standards. The
treatment method ultimately used would be determined during
the pre-design phase. The tars and the highly contaminated
soils would be sampled and treated separately to the maximum
extent possible to avoid diluting the tar in the process. For
the soil, alternate treatment levels under a treatability
variance can be based on data from actual treatment of the
soil. This would be established during the pre-design with
the most appropriate treatment technology.
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Once treated the tar residue would be loaded onto trucks for
transportation to a secure, CERCLA off-site policy compliant,
RCRA hazardous waste landfill for disposal. If the treated
soil is below health based levels, it would be considered
clean. contaminated soil is not a waste, but only a media
containing waste. When the contaminants have been removed
below health based levels, the soil no longer contains the
waste and no longer needs to be treated as a hazardous waste.
Thus, clean soil could be used as backfill at the site.
The remaining soil with an excess cancer risk level less than
1 x 10-2 and greater than 1 x 10 -6 would be bio-remediated in-
situ to the maximum extent practicable with the goal being
Michigan Act 307 Type B levels. If it is determined during
the remediation that bio-remediation can not achieve the
desired cleanup goal, the treated soils would be contained on-
site with the installation of a hazardous waste cap. The bio-
remediation involves the addition of nutrients and oxygen to
the media to promote bio-degradation of contaminants by
microorganisms. The exact amenability and effectiveness to
this technology would be determined in pre-design treatability
studies.
As in Alternative 2, an interim groundwater containment system
would be installed to keep the contaminant plume from
migrating further. (The addition of nutrients to aide bio-
remediation as described in Alternative 2 is not applicable to
this alternative.) Because the groundwater containment is an
interim measure, groundwater cleanup standards are waived.
Final remedy for the groundwater, including the establishment
of clean-up standards, will be addressed in the second
operable unit.
Alternative 7 has an estimated capital cost of $47.6 million
and an estimated annual operation and maintenance cost of
$874,800. The estimated present worth cost is $51.4 million.
IX. COMPARATIVE'ANALYSIS OF ALTERNATIVES
In accordance with the NCP, the relative performance of each
alternative is evaluated using the nine criteria, 40 CFR
Section 300.430(e) (9) (iii), as a basis for comparison. An
alternative providing the "best balance" o'f tradeoffs with
respect to the nine criteria is determined from this
evaluation.
A detailed analysis was performed on the seven alternatives
using the nine evaluation criteria in order to select a site
remedy. The following is a summary of the comparison of each
alternative's strength and weakness with respect to the nine
evaluation criteria. These nine criteria are: 1) overall
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21
protection of human health and the environment; 2) compliance
with applicable or relevant and appropriate requiremants
(ARARs); 3) long-term effectiveness and permanence; 4)
reduction of toxicity, mobility, or volume through treatment;
5) short-term effectiveness; 6) implementability; 7) Cost;
8) State acceptance; 9) community acceptance.
Overall Protection of Human Health and the Environment
This criterion addresses whether a remedy provides adequate
protection of human health and the environment and describes
how risks posed through each exposure pathway are eliminated,
reduced, or controlled through treatment, engineering
controls, or institutional controls.
Alternative 1, No Action, is not protective of human health
and the environment because nothing is done to the
contaminated media. The risks associated with the site are
not changed.
Alternatives 2 through 7 are all protective of human health
and the environment as the risks due to the tar and the
contaminated soils are minimized by removal, treatment, or
containment of the media.
Alternatives 2 through 4 are similar in that each reduces the
direct contact threat and the continuing contamination of the
groundwater by removing and incinerating the tar and the
highly contaminated soils. In addition, each of these
alternatives addresses the low level contaminated soils.
Alternative 2 bio-remediates the low level contaminated soils.
Alternative 3 excavates, treats, and disposes these soils off-
site. Alternative 4 thermally desorbs the soils. The actions
taken in Alternatives 2 through 4 will result in an acceptable
risk level at the site by minimizing or eliminating potential
exposure. Also, they provide high levels of effectiveness and
permanence as residual risks are eliminated since no untreated
wastes are left on the site.
Alternatives 5 through 7 each address the risks at the site in
a different manner. Alternative 5'minimizes risk by removal
and treatment of the tar and all of the contaminated soils and
then disposal in an off-site licensed hazardous waste
landfill. Alternative 6 minimizes the risk at the site by
eliminating the exposure pathways. Direct contact threats and
continuing contamination of the groundwater are mitigated
through the removal of the tar and all of the contaminated
soils and disposal on-site in two adjoining RCRA containment
cells. Alternative 7 reduces risk by removing, treating, and
then disposing the tar and highly contaminated soils in an
off-site hazardous waste landfill. Alternative 7 also bio-
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remediates the low level contaminated soils. Thus,
Alternatives 5 through 7 also provide high levels of
effectiveness and permanence. By containing the hazardous
waste, these alternatives reduce risk at the site through
elimination of the exposure pathway.
Each of the seven alternatives provides additional protection
through the interim groundwater containment system, which
prevents further migration of the contaminant groundwater
plume. This measure protects the public from the potential
migration of site contaminants, some of which have been found
to exceed MCLs on the Tar Lake property.
ComDliance with AODlicable
Reauirements (ARARs)
or
Relevant
and
ADDroDriate
This criterion evaluates whether a remedy meets applicable or
relevant and appropriate requirements set forth in Federal and
state environmental laws pertaining to the site or proposed
actions or if a wavier is justified. ARARs are discussed in
more detail in statutorv Determinations.
All of the alternatives, except for the no action alternative,
will comply with Federal and State ARARs. The major ARARs
that will be complied with include: RCRA and Michigan
Hazardous Waste Management Act (Act 64); which address the
handling of hazardous materials (including requirements for
incineration, transportation, land disposal restrictions, and
minimum technology requirements for landfills, and hazardous
waste landfill covers); the Clean Air Act and Michigan's Air
POllution Control Act (Act 348), which address air emissions
from the excavation and incineration processes; Michigan Water
Resources Act (Act 245), which addresses groundwater quality;
and Michigan Enviro1Ul1ental Response Act (Act 307), which
addresses cleanup type.
"To Be Considered" requirements that will be met are: u.s.
EPA's Off-site pOlicy, which ensures that CERCLA wastes are
sent to a CERCLA off-site compliant, RCRA-permitted landfill;
Reauirements for Hazardous Waste Landfill Desian.
Construction. and closure EPA/62S/4-89/002, AUgust 1989 and
Final Covers on Hazardous Waste Landfills and Surface
Imooundments EPA/S30-SW-89-047, July 1989, which address the
design and construction of the containment cells.
The interim groundwater containment in not a final cleanup of
groundwater at Tar Lake. Its purpose is to prevent the
contaminants from spreading. The second operable unit at the
site will addresses the final groundwater cleanup levels.
Therefore, a waiver of groundwater cleanup standards shall be
invoked for this operable unit.
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Lona-Term Effectiveness and Permanence
This criterion refers to expected residual risk and the
ability of a remedy to maintain reliable protection of human
health and the environment over time, once cleanup goals have
been met. .
Alternative 1, No Action, does not satisfy this criterion
because is does not mitigate any of the risks presently at the
site.
Alternatives 2 through 4 permanently minimize the risks
associated with the tar and the highly contaminated soils
through excavation and incineration. Each alternative also
address the low level contaminated soils but through different
methods. Alternative 2 bio-remediates the soils. Alternative
3 excavates, treats, and disposes the soils off-site.
Al ternati ve 4 thermally des orbs the soils. Thus, Al ternati ves
2 through 4 provide high levels of effectiveness and
permanence because there are no untreated waste left on the
site once the alternatives are implemented.
Alternatives 5 through 7 are also effective in the long term.
Alternative 5 eliminates risks by excavating and treating the
tar and all of the contaminated soils and then disposing the
hazardous treatment residue off-site in a permitted hazardous
waste landfill. No untreated wastes are left on the site.
Alternative 6 mitigates ~he risks at the' site by
excavating/consolidating the tar and all of the contaminated
soils and containing them on-site in two adjoining RCRA
containment cells. The protective measures of the containment
cells ~ill provide reliability to ensure that any exposures
will ;':E. minimized. Proper long-term operation and maintenance
will assure the integrity of the cells. Alternative 7
mitigates the risk from the tar and highly contaminated soils
by treating them and disposing the hazardous residuals off-
site in a permitted hazardous waste landfill. The low level
contaminated soils are treated through bio-remediation. Thus,
there are no untreated wastes left on site with Alternative 7.
Alternatives 2, 3, 4, 5, and 7 involve the removal of
contaminated materials, with subsequent treatment, and offer
the highest level of long-term protectiveness and permanence.
Alternative 6 contains the contaminated material in
engineered containment cells and provides an adequate level of
long-term effectiveness and permanence.
Reduction of Toxicitv. Mobilitv. or Volume Throuah Treatment
This evaluation addresses the statutory preference for
selecting remedial actions that employ treatment technologies
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which permanently and significantly reduce toxicity, mobility,
or volume of the hazardous substance as their principal
element.
Alternative 1, No Action, provides no treatment and thus does
nothing to affect toxicity, mobility, or volume of the waste
material.
Alternatives 2 though 4 reduce the toxicity, mobility, and
volume of the principal threat, which is the tar and the
highly contaminated soils, through incineration. This
satisfies the statutory preference for the use of treatment as
a principal element. In addition, each of the alternatives
addresses the low level contamination. Alternative 2 reduces
the toxicity, mobility, and volume through treatment of the
low level contaminated soils through bio-remediation.
Alternative 3 does not treat the low level contaminated soils
but rather removes and disposes of it off-site. Alternative
4 reduces toxicity, mobility, and volume of the low level
contaminated soils through thermal desorption.
Alternative 5 reduces the toxicity, mobility, and volume of
the contaminants through the treatment that is required by
LDRs prior to the off-site disposal in a permitted hazardous
waste landfill. This satisfies the statutory preference for
the use of treatment as a principal element. Alternative 6
reduces the ability of the contaminants to migrate through
excavation and consolidation on-site in two adjoining RCRA
containment cells, but this is not through treatment and does
not satisfy this requirement. Alternative 7 reduces toxicity,
mobility, and volume by treating the tar and highly
contaminated soils prior to disposal in an off-site hazardous
waste landfill and by bio-remediation of the low level
contaminated soils. Consequently, Alternative 7 satisfies
this criterion.
Short-Term Effectiveness
This criterion addresses the risks the remedy may pose to site
workers, the community, and the environment during the
construction and implementation phase until cleanup goals are
ach~eved and the time it takes to achieve these cleanup goals.
with respect to protection of the community, Alternative 1
does not pose any additional risks to the community as no
action is taken. Alternatives 2 through 7 could introduce
risks to residents through the possible release of volatile
chemicals through the excavation of the tar and contaminated
soils. These risks, however, will be minimal and can be
controlled through air monitoring. If it is determined that
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volatiles are being emitted into the air and pose a threat to
the residents, immediate action will be taken to mitigate the
threat.
There are no risks to workers with Alternative 1 as no work is
being performed. Alternatives 2 through 7 could introduce
risks to workers. through the possible release of volatile
chemicals through the excavation. These risks can be
controlled by following safe working practices and
implementation of the health and safety plan that will be
developed for the Remedial Design/Remedial Action. This
health and safety plan will indicate the different levels of
protection, including but not limited to respiratory
protection, and when these protective devices are to be used
to ensure worker safety.
With respect to environmental impacts, Alternative 1 will have
continued migration of contamination from. the tar to the
groundwater as the source remains partially immersed in the
groundwater. Alternatives 2 through 7 could result in the
release of some contaminants from the tar into the groundwater
during the excavation process. However, the interim
groundwater containment remedy will capture the contaminated
groundwater and prevent its migration.
Evaluation of the time to implement the alternatives reveals
the following estimates: Alternative 1 will not take any time
to implement. Alternatives 2 through 7 will take 3 years at
a minimum to implement. .
ImDlementabilitv
This criterion. addresses the technical and administrative
feasibili ty of implementing a remedy, including the
availability of materials and services needed.
Alternative 1 has nothing to implement. Alternatives 2
through 7 are technically and administratively feasible.
Alternatives 2, 3, 4, 5, and 7. use excavation and
incineration, which are established technologies. With
respect to the low level contaminated soils, Alternative 2, 4,
and 7 use eith~r bio-remediation or thermal desorption, which
are innovati': technologies. However, these' innovative
technologies 'e being employed at other sites and have had
successful pilot tests performed for contaminants similar to
those at Tar Lake. Alternatives 3, 5, and 7 utilize disposal
at an off-site licensed facility. It should be noted that
even though there are licensed hazardous waste landfills that
can accept the waste, they may be reluctant to accept waste
from a Superfund site. Alternative 6 involves construction
and disposal of waste in on-site RCRA containment cells. This
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is an established technology. Tests conducted by u.s. EPA
indicate that with the addition of solidification agents, 17.5
percent bentonite and 35 percent cement, the tar should be
able to physically support the weight of a landfill cover.
The pump and treat system in each alternative for interim
groundwater containment is also an established technology and
is not expected to present implementability problems.
The property needed to conduct the remedial activities are
owned by PRPs. Thus, access is not expected to present any
problems.
Cost
This criterion compares the capital,
maintenance, and pre~ent worth cost
alternatives at the site.
annual operation and
of implementing the
The following
alternatives.
ar
the
cost
estimates
for
each
of
the
Alternative CaDital Cost Annual O&M Cost Present Worth
1 $0 $0 $0
2 $47,600,000 $874,800 $51,400,000
3 $55,100,000 $791,800 $58,500,000
4 $60,800,000 $791,800 -$64,200,000
5 $48,900,000 $791,800 $52,300,000
6 $16,700,000 $791,800 $20,100,000
7 $47,600,000 $874,800 $51,400,000
Present worth was calculated for five year at 5 percent.
All of the Alternatives, except for Alternatives 1 and 6,
include incineration of the tar and at least part of the
contaminated soils. Alternatives 2 - 4 include incineration
as the primary treatment element. Al ternati ves 5 and 7
examine off-site landfilling but because RCRA Land bisposal
Restrictions are triggered, treatment standards must be met
prior to disposal. Incineration is also used in these two
alternatives as a means to meet the treatment standards
because the tar is similar to K087 waste and K087 treatment
standards are based on incineration. with the large volume of
materials and the high unit cost of the treatment, the $28
million incineration cost represents approximately 50% of the
capital costs for each of these alternatives. When the other
parts of the alternatives are included, these remedies are in
the $50 - $60 million range, which brings into question the
cost effectiveness.
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Alternative 6 is not subject to the RCRA Land Disposal
Restrictions. The RCRA containment cells would be constructed
within the area of contamination (AOC) and the tar and
contaminated soils transferred into these cells without moving
it outside the AOC or placing it into a separate unit.
Because placement, as defined by RCRA, does not occur, LDR
treatment standards are not triggered and incineration is
avoided.
state Acceptance
The state of Michigan has verbally concurred with u.s. EPA's
selection of Alternative 6 as the preferred "remedial
alternative as presented in the next section. A concurrence
letter has not been received yet.
Communitv Acceptance
Based on the comments recei ved by U. S .
alternative appears to be acceptable
Community concerns are addressed
Responsiveness Summary.
EPA, the selected
to the community.
in the attached
x. SELECTED REMEDY
Based upon consideration of the requirements of CERCLA, as
amended by SARA, and the NCP, the detailed analysis of the
alternatives, and public comment, u.S. EPA has determined that
Alternative 6 - Removal and Disposal of Tar and Contaminated
Soils in On-site RCRA Cells; Interim Groundwater Containment
is the most appropriate remedy for the first operable unit at
the Tar Lake site.
The components of the selected remedy are as follows:
A)
pre-desiqn study
The pre-design phase shall include but not be limited to:
(1) laying out a grid over Tar Lake and suspected
locations of tar and taking tar samples in order to get
a representation of the extent of the tar and its
constituents; (2) based on the results of the tar
characterization performed in (1) above, examine the
possibility of recycling/reusing all or a portion of the
tar; (3) soil sampling and analysis in and around Tar
Lake, extending to the adjacent landfill, to
characterize the extent and constituents of
contamination, including a determination of background
soil levels; and, (4) treatability studies to determine:
the effectiveness of carbon adsorption to meet
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groundwater discharge limits, the effectiveness of other
groundwater treatment options to meet discharge
limitations if carbon adsorption can not, and the amount
of solidification agents to be added to the tar so it can
support the weight of a landfill cover.
B)
Excavation/consolidation
The tar and the all of the contaminated soils (soils with
an excess cancer risk level greater than 1 x 10-6) in and
around Tar Lake, extending to the adjacent landfill shall
be excavated/consolidated. The vertical and horizontal
extent of excavation/consolidation shall be further
defined during the remedial design. Initial estimates of
volume are 30,000 yd3 of tar and 40,000 yd3 of
contaminated soils. Dewatering shall be done to
facilitate the excavation/consolidation. The exact
number and placement of the dewatering extraction wells
shall depend on the areal extent and depth of
contamination.
C)
RCRA containment cells
The tar (including solidification agents) and
contaminated soils shall be consolidated in two adjoining
RCRA containment cells constructed in the area of
contamination. The cells will meet RCRA minimum
technology requirements, which includes at a minimum,
double. liners, leachate collection system, and
groundwater monitoring. The first containment cell will
be sized to hold the tar, estimated to be 30,000 yd3 but
to be better defined during the pre-design.
Solidification agents, bentonite and cement, shall be
added to the tar to give it the physical stability to
support the weight of the RCRA Subtitle C hazardous waste
landfill cover used to close the cell. The second
containment cell shall be sized to hold the. contaminated
soils. The two cells shall be constructed sequentially.
First, the containment cell for the tar shall be
constructed so that the tar can be excavated and
deposited in the cell, so that additional sampling can be
performed on the soils underneath to better determine the
extent of contaminated soils. Once the volume of
contaminated soils is known, final sizing and
construction of the second containment cell shall be done
and the contaminated soils shall be disposed of. Both
cells shall be closed with RCRA Subtitle C hazardous
waste landfill covers.
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D)
Interim Groundwater containment
An interim groundwater containment system shall be
installed to keep the contaminant plume from migrating.
This includes: (1) installation of a pump and treat
system for the containment of contaminated groundwater
(including groundwater from the excavation dewatering
process) and the treatment of water ponded on Tar Lake;
(2) reinjection of the treated groundwater, which meets
Act 307 Type B standards, upgradient of the extraction
wells so that a closed loop system is formed; (3)
implementation of institutional controls which shall
restrict groundwater usage within the areas of the
existing or potential contaminant plume; and (4)
implement a groundwater monitoring program during the
Remedial Design/Remedial Action to detect changes in
contaminant concentrations and plume location.
Remediation Goals
The purpose of this operable uni t response action is to
control risks posed by the tar and contaminated soils at Tar
Lake, which are a continuing source of groundwater
contamination. The most serious health risks associated with
the site are from ingestion of the contaminated groundwater
and soils by future residents at the Tar Lake site. The
future use scenario indicate unacceptable risks to human
health as the carcinogenic risk is 8 x 10-4 for future adult
residents. The non-carcinogenic hazard index is 24 for future
residents. These risks are outside of u.s. EPA's acceptable
risk ranges. The cleanup levels presented in Section VI:
CleanuD Standards, shall be achieved for the soil at Tar Lake.
Since the groundwater containment is an interim measure,
cleanup standards will not be attained in this operable unit.
Final groundwater cleanup levels will be addressed in the
second operable unit.
Estimated Costs
The following is the estimated cost summary for the selected
remedy.
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Alternative 6
Removal and Disposal of Tar and contaminated soils
in on-site RCRA cells; Interim Groundwater containment
CAPITAL COSTS:
Excavation
Disposal of Tar in RCRA Cell
(includes $3.8 million for
solidification agents)
Disposal of Soil in RCRA Cell
Groundwater containment System
Design and contingencies
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS:
Excavation (dewatering)
Groundwater containment System
TOTAL AHHUAL OiM COSTS
$4.1 million
$5.4 million
$2.1 million.
$1.0 million
$4.1 million
$16.7 million
$144,000
$647.800
$791,800
TOTAL PRESENT WORTH COSTS..............$20.1 million
XI. STATUTORY DETERMINATIONS
u.S. EPA's primary responsibility at Superfund sites is to
select remedial actions that are protective of human health
and the environment. In addition, section 121 of CERCLA
establishes several statutory requirements and preferences.
These require that the selected remedial action for the site
comply with applicable or relevant and appropriate
requirements established under Federal and State environmental
laws, unless a waiver is granted. The selected remedy must
also be cost-effective and utilize permanent solutions and
alternate treatment technologies to the maximum extent
practicable. Finally, the statue includes a preference for
remedies that include treatment as a principal element. The
following sections discuss how the selected remedy for the Tar
Lake site addresses these statutory requirements.
A) protection of Human Health and the Environment
. The selected remedy for the Tar Lake site protects human
health and the environment through the elimination of exposure
pathways with the containment of the tar and the contaminated
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soils. Excavation and consolidation in on-site RCRA
containment cells. will eliminate the direct contact and
ingestion pathways as well as removing a continuing source of
groundwater contamination. The containment cells will
minimize precipitation infiltration and leaching of the
contaminants from the tar and soils.
Additional protection is provided through the implementation
of the interim groundwater containment system. The
contaminated groundwater is prevented from further migration
until the second operable unit addresses the final groundwater
cleanup. This measure protects the public from the movement
of site contaminants that exceed MCLs on the Tar Lake site.
No unacceptable short-term risks will be caused by the
implementation of the remedy. The excavation/ consolidation of
the tar and contaminated soils could release VOCs, however,
resident and site worker risks will be minimized through air
monitoring and immediate action if there is threat posed;
following safe work practices; and, implementation of the
health and safety plan that shall be developed for the
Remedial Design/Remedial Action.
B) Comp~iaDce with ARARs
The selected remedy shall comply with Federal and/or. state,
where more stringent, applicable or relevant and appropriate
requirements (ARARs) listed below:
1) Chemical-Specific ARARs
Chemical-specific ARARs regulate the release to the
environment of specific substances having certain
chemical characteristics. Chemical-specific ARARs
typically determine the extent of cleanup at a site.
Federal ARARs
Maximum Contaminant Levels '(MCLs) and to a certain extent
non-zero Maximum contaminant Level Goals (MCLGs), the
Federal drinking-water standards promulgated under the
Safe Drinking Water Act (SDWA), are applicable to
municipal water supplies servicing 25 or more people. F.t
the Tar Lake site, MCLs and MCLGs are not applicable, but
are relevant and appropriate since the aquifer in the
area of contamination is suitable for use as a source of
drinking water in the future. MCLGs are relevant and
appropriate when the standard is set at a level greater
than zero (for non-carcinogens), otherwise, MCLs are
relevant and appropriate. CERCLA section 121(d) (4) (A)
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provides that when the remedial action selected is only
part of a total remedial action that will attain such
level of standard or control when completed, otherwise
applicable or relevant and appropriate requirement may be
waived. Since the groundwater containment at Tar Lake is
an interim measure, with final groundwater cleanup to be
addressed by the second operable unit, these ARARs are
waived.
state ARARs
Rules 705(2) and (3),707 - 715,717(2),719(1), and 723
of the Michigan Environmental Response Act (Act 307)
Administrative Rules are ARARs at the Tar Lake site.
Groundwater cleanup standards can be derived under Type
A, B, or C criteria. The groundwater containment at Tar
Lake is an interim measure, with final groundwater
cleanup to be addressed by the second operable unit.
Therefore, these ARARs are waived as provided by CERCLA
section 121(d) (4) (A).
2) Location-SDecific ARARs
Location-specific ARARs are those requirements
relate to the geographical position of a site.
that
No location specific ARARs have been identified.
3) Action-SDecific ARARs .
Action-specific ARARs
acceptable treatment
hazardous substances.
are
and
requirements that define
disposal procedures for
Federal ARARs
The Clean Air Act standard for total suspended
particulates (National Ambient Air Quality Standard for
PM-10, 40 CFR 50.6) addresses particulate matter with a
diameter of 10 micrometers or less. This is relevant and
appropriate at Tar Lake for the excavation/consolidation
of the tar and contaminated soils.
RCRA subtitle C requirements regulate the treatment,
storage, and disposal of hazardous waste. Because the
tar is similar to RCRA K087 waste, i.e., decanter tank
tar sludge from coking operations, RCRA Subtitle C
requirements are relevant and appropriate with respect to
the handling and disposal of the tar and contaminated
soils as well as to the residue from the groundwater
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containment treatment system. In particular, 40 CFR Part
264 Subpart N, Landfills addresses the requirements for
hazardous waste landfills. This includes: minimum
technology requirements for landfills, as set forth in 40
CFR Section 264.301 (c), and landfill closure requirements
specified in 40 CFR section 264.310.
RCRA Land Disposal Restrictions (LDRs), 40 CFR Part 268,
place restrictions on the land disposal of RCRA hazardous
waste. Because the RCRA containment cells will be
constructed in the area of contamination, LDR treatment
standards will not be triggered since "placement" (as
defined by RCRA) will not occur. Thus, RCRA LDRs are not
ARARs at the Tar Lake site.
State ARARs
Michigan's Soil Erosion and Sedimentation Control Act
(Act 347) regulates earth changes which involve more than
one acre or is within 500 feet of a lake or stream. Act
347 is applicable' to the tar and soil excavation/
consolidation as the area involved is more than one acre.
Appropriate erosion and sedimentation control measures
shall be planned.
The Michigan Environmental Response Act (Act 307)
provides for the identification, risk assessment, and
evaluation of contaminated sites within the State. The
U.S. EPA has determined that Rules 705(2) and (3),707 -
715,717(2),719(1), and 723 are relevant and appropriate
to the Tar Lake site in compliance with section 121 (d) (2)
of CERCLA. These rules provide for the selection of a
remedy which attains a degree of clea~up which conforms
to one or more of ~hree levels of cleanup - either Type
A (cleanup to background levels), Type B (cleanup to
risk-based levels), or Type C (cleanup to risk-based
levels under site-specific considerations). u.S. EPA has
determined that the soils cleanup/excavation will meet
Type B levels and the containment of tar and soils is a
Type C cleanup.
Michigan Water Resources Act (Act 245) Part 22 addresses
groundwater quality in useable aquifers. This applies to
the reinjection of the treated groundwater from the
containment system. A closed loop system shall be formed
by reinjecting the groundwater, which shall be treated to
meet Act 307 Type B levels, upgradient of the extraction
wells. This closed loop reinjection system complies with
the substantive requirements set forth in Act 245.
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34
Michigan's Hazardous Waste Management Act (Act 64)
regulates the generation, transport, treatment, storage,
and disposal of hazardous waste. with respect to the
containment cells, Act 64 is relevant and appropriate.
The applicable sections of Act 64 have incorporated RCRA
by reference. Therefore, by meeting the RCRA
specifications and requirements for the containment
cells, the substantive requirements of Act 64 will also
be met.
4) To Be Considered
In addition to legally binding laws and regulations, many
Federal and state environmental and public health
programs also develop criteria, advisories, guidance, and
proposed standards that are not legally binding, but that
provide useful information or recommended procedures.
Reauirements for Hazardous Waste Landfill Desian.
Construction. and Closure EPA/625/4-89/002, August 1989,
addresses the design and construction of landfills.
This guidance document applies to the design and
construction of the RCRA containment cells at Tar Lake.
Final Covers on Hazardous Waste Landfills and Surfac.
ImDoundments EPA/530-SW-89-047, July 1989, addresses the
design and construction of landfill covers. This
guidance document applies to the design and construction
of the hazardous waste landfill covers that shall be used
to close the RCRA containment cells at Tar Lake.
C) Cost Effective
The selected remedy is cost effective because it has been
determined to provide overall effectiveness proportiona~ to
its cost. Alternative 6 provides adequate protection of human
'health and the environment for less cost than any of the other
alternatives evaluated (excluding the no action alternative).
All of the other alternatives, except for Alternative 1, no
action, include incineration of the tar and some portion of
the contaminated soils. In Al ternati ves 2, 3, and 4,
incineration was the primary treatment element. Alternatives
5 and 7 examined off-site landfilling of the tar and
contaminated soils. However, RCRA LDRs were triggered and
treatment standards had to be met before the waste could be
disposed because the tar is similar to K087 waste, decanter
tank tar sludges from coking operations. These treatment
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standards for K087 were based on the use of incineration.
Therefore, it is likely that incineration will have to be used
in order to meet these standards at Tar Lake. With the large
volume of wastes and the high unit cost of incineration, the
$28 million cost for incineration represents approximatel', 50
percent of the capital cost for each of the alternatives,
other than Alternatives 1 and 6. When the other component
costs are included, the alternatives which include
incineration are in the $50 million to $60 million range.
This brings in the issue of cost effectiveness.
Alternative 6 is not subject to the RCRA LDRs because the RCRA
containment cells shall be constructed within the area of
contamination (AOC). The tar and contaminated soil would be
transferred into these cells without moving it outside the AOC
or placing it into a separate unit. Therefore, LDR treatment
standards are do not have to be met because placement, as
defined by RCRA, does not occur.
Al ternati ves 2 , 3 , 4 , 5 , and 7, each of which include
incineration as part of the treatment at the site, provide a
high level of protectiveness by treating the tar and
contaminated soils. Alternative 6 also provides a high deqree
of protectiveness by eliminating the exposure pathway through
the containment of the tar and contaminated soils, but at
about one-third the cost. with a present worth cost of $20.1
million, Alternative 6 is the most cost effective remedy for
this operable unit at Tar Lake.
D) utilization of Permanent Solution and Alternative Treatment
Technoloqies to the Maximum Extent Practicable
The selected remedy represents the maximum extent to which
permanent solutions and alternate treatment technologies can
be utilized in a cost effective manner for the Tar Lake site.
Of those alternatives that are protective of human health and
the environment and comply~. ~h ARARs, Alternative 6 provides
the best balance of tra~~offs in te~s of long-term
effectiveness and permanence, reduction of toxicity, mobility,
or volume through treatment, short-term effectiveness,
implementability, and cost, and considering state and
community acceptance.
The selected remedy provides a high degree of long-term
effectiveness and permanence by excavating/consolidating the
tar and contaminated soils and containing them in on-site RCRA
containment cells. The protective measures of the RCRA
containment cells (i.e., double liners, leachate collection
system, groundwater monitoring) will provide reliability to
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ensure minimal exposure potential. Proper long-term operation
and maintenance will assure the integrity of the containment
cells. The containment reduces the ability of the
contaminants to move, even though it is not through treatment.
The other alternatives which do utilize treatment to reduce
toxicity, mobility, or volume are not cost effective. Short-
term effectiveness and. implementability are similarly
satisfied for all of the alternatives evaluated. Alternative
6 is the most cost effective remedy for the Tar Lake site.
E) Preference for Treatment as a principal Element
The containment of the tar and contaminated soils, which as a
continuing source of groundwater contamination is the
principal threat at the Tar Lake site, does not employ
treatment as a principal element. The alternatives which
included treatment (i.e., incineration) as a principal
element, were not cost effective. These alternative costed up
to three times as much as the selected remedy without
providing additional protection of human health and the
environment. Alternative 6 provides the best balance with
respect to the evaluation criteria even though treatment is
not a principal element.
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