PB95-963124
EPA/AMD/R05-94/261
March 1995
EPA Superfund
Record of Decision Amendment:
Arrowhead Refinery Co.,
Hermantown, MN
2/9/1994
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Amendment To The Record of Decision
Declaration
Site Name and Location
Arrowhead Refinery Superfund Site
St. Louis County
Hermantown, Minnesota
Statement of Basis and Purpose
This decision document amends the selected remedial action for the
Arrowhead Refinery Superfund Site (Arrowhead) developed in
accordance with the Comprehensive Environmental Response,
Compensation and Liability Act of 1980 (CERCIA) , as amended by the
Superfund Amendments and Reauthorization Act of 1986 (SARA) and,
to the extent practicable, the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP). This amendment to
the Record of Decision (AROD) makes fundamental changes to the
remedy selected in the 1986 Record of Decision (ROD).
This AROD does not make " fundamental changes* (within the meaning
of the Environmental Protection Agency's Office of Solid Waste and
Emergency Response Directive 9355.3-02FS-4, "Guide to Addressing
Pre-ROD and Post ROD Changes", April 1991) to the groundwater
remedy selected in the ROD. Therefore, this AROD does not
constitute an amendment of that* groundwater remedy. However, this
AROD does document minor differences in the groundwater remedy
which the Agency intends to implement.
This AROD is based on the administrative record file for the
Arrowhead Site.
The State of Minnesota, through the Minnesota Pollution Control
Agency (MPCA), has verbally concurred with the amended remedy.
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 AROD, may present an imminent and substantial
endangerment to the public health, welfare and/or the environment.
Description of the 19*6 BOD Remedy
»
The site contaminated media were originally divided into three
parts: 1) groundwater, 2) sludge,.filter cake and oil saturated
peat (source material) and 3) contaminated soils and sediment?.
The 1986 ROD specified that the following remedial actions be
implemented:
e Extend the nearby municipal water system to replace private
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water supplies to ten residences most likely to be affected by
groundwater contamination from Arrowhead. Abandon individual
wells formerly used as drinking water supplies in accordance with
state well codes.
• Design and install a groundwater extraction and treatment
system to capture and restore the contaminated groundwater beneath
the site and to prevent off-site migration of the contaminated
plume. Discharge extracted contaminated groundwater to the
Western Lake Superior Sanitary District waste water treatment
facility (WLSSD). Potential ingeetion of on-site groundwater has
an excess lifetime cancer risk of 10'2 for either a residential or
a commercial/industrial setting. Operate the extraction and
treatment system until 10"6 lifetime cancer risk levels are
achieved (estimated at 25-50 years).
• Excavate and incinerate on-site, 4,600 yds' of source
material and 20/500 yds3 of contaminated soils and sediments with
concentrations of carcinogenic Po?"nucl«»T Aromatic Hydrocarbons
(PAHs) and Volatile Organic Compounds (VOCs) that exceed
the 10"* excess lifetime cancer risk in a commercial/industrial
setting and/or concentrations of lead and other non-carcinogens
that exceed adult chronic acceptable intake levels (AIC).
Determine the leaching characteristics of the resulting ash. If
the ash is non-hazardous by the EP toxicity test, place it back
on-site. if hazardous, stabilize and place in a subtitle D
landfill.
• Conduct further field studies to ennance site
characterization. In response to a request from the Minnesota
Pollution Control Agency (MPCA), the ROD stated that the
technologies eliminated early in the FS - vitrification, chemical
fixation, and cementation • would be reevaluated and that bench-
scale studies would be considered.
The total cost of this remedy was estimated at $23,000,000 in
1986.
The groundtfatex remedial design and construction have been
completed. Minor change* in the operation and maintenance of the
extraction and treatment system, which do not constitute
fundamental or significant change** including point of compliance
and cleanup levels, are discussed.
Explanation of Fundamental Remedy Change
EPA conducted a solvent extraction study which indicated that this
technology would not be a suitable technology for the Arrowhead
Site. MPCA and the Minnesota Arrowhead Site Committee (MASC), a
group of PRPs, each conducted treatability studies in an effort to
find a less costly alternative to incineration for both source
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material, soils and sediments. Technologies evaluated included
solid phase and slurry phase bioremediation,
stabilization/solidification, soil washing with lead removal,
thermal destruction in a cement kiln or other boilers and
industrial furnaces, and chemical dissociation with lead recovery.
With respect to the source material, the results of these studies
indicated that chemical disassociation of source material would be
the optimal method of remediation. This technology removes lead
from the source material and provides a saleable 'off-spec* fuel.
Additionally, the lead may be recovered in a smelting operation.
Another very important discovery resulting from these studies was
that as soil samples were obtained and analyzed, PAH and voc
levels were consistently found to be below health based levels of
concern. This .was verified in a separate field sampling study
conducted in June 1993. Upon review of the early field studies,
it was found that there were only two PAH "hot spots" in the soil
and that these were likely due to cross contamination with filter
caka. As a consequence of these findings, the soil and sediment
contaminant of concern is now only lead. Therefore, treatment
technologies which targeted organic compounds in soils and
sediments, including incineration, have been discounted from
further consideration.
Description of Amended Remedy
The major elements of the selected amended remedy include:
• Excavation of sludge and filter cake using a visually
contaminated standard; total volume approximately 4,600 - 6,100
cubic yards.
• On-site treatment of sludge and filter cake by chemical
disassociation (re-refining) of the toxic compounds within the
sludge/filter cake matrix to produce a saleable "off-
specification" fuel and to recover lead in a smelting operation or
to stabilize and place in a permitted RCRA Subtitle D facility.
• Excavation of visually contaminated soils and sediments,
followed by placement of soils and sediments in a permitted RCRA
Subtitle D facility.
Discussion of Change in Grovmdwater Rowdy
• Operation and maintenance of the ground-water extraction
and treatment system until groundwater at the site perimeter meets
Maximum Contamination Limits (MCLs) .
Statutory Determinations
The selected remedy is protective of human health and the
environment, attains Federal and State requirements that are
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applicable or relevant and appropriate for this remedial action
and Is cost effective. This remedy satisfies the statutory
preference for remedies that employ treatment: that reduces
mobility, toxicity or volume (MTV) as a principle element and
utilizes permanent solutions and alternative treatment (or
resource recovery) technologies to the magimnn extent possible.
Because this remedy will not result in hazardous substances
remaining on-site above health-based levels, the five-year review
will not apply to this action.
^ Approved Disapproved
Regional Administrator
Date
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