[Federal Register Volume 85, Number 133 (Friday, July 10, 2020)]
[Proposed Rules]
[Pages 41487-41495]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-14912]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 300
[EPA-HQ-SFUND-2004-0004; FRL-10011-56-Region 7]
National Oil and Hazardous Substances Pollution Contingency Plan;
National Priorities List: Deletion of the Annapolis Lead Mine Superfund
Site
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule; notice of intent.
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SUMMARY: The Environmental Protection Agency (EPA) Region 7 is issuing
a Notice of Intent to Delete the Annapolis Lead Mine Superfund Site
(Site) located in Annapolis, Missouri, from the National Priorities
List (NPL) and requests public comments on this proposed action. The
NPL, promulgated pursuant to section 105 of the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA) of
1980, as amended, is an appendix of the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP). The EPA and the state of
Missouri, through the Missouri Department of Natural Resources (MDNR),
have determined
[[Page 41488]]
that all appropriate response actions under CERCLA have been completed,
other than operation and maintenance, monitoring and five-year reviews.
However, this deletion does not preclude future actions under
Superfund.
DATES: Comments must be received on or before August 10, 2020.
ADDRESSES: Submit your comments, identified by Docket ID no. EPA-HQ-
SFUND-2004-0004, by one of the following methods:
https://www.regulations.gov. Follow on-line instructions
for submitting comments. Once submitted, comments cannot be edited or
removed from Regulations.gov. The EPA may publish any comment received
to its public docket. Do not submit electronically any information you
consider to be Confidential Business Information (CBI) or other
information whose disclosure is restricted by statute. Multimedia
submissions (audio, video, etc.) must be accompanied by a written
comment. The written comment is considered the official comment and
should include discussion of all points you wish to make. The EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e. on the web, cloud, or other file sharing
system). For additional submission methods, the full EPA public comment
policy, information about CBI or multimedia submissions, and general
guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
Email: gunter.jason@epa.gov or 69021b08040c1b470c050013080b0c1d01290c1908470e061f.
Phone: Public comment by phone may be made by calling
Jason Gunter at (913) 551-7358, or Elizabeth Kramer at 913-551-7186.
Written comments submitted by mail are temporarily
suspended and no hand deliveries will be accepted. We encourage the
public to submit comments via https://www.regulations.gov.
Instructions: Direct your comments to Docket ID no. EPA-HQ-SFUND-
2004-0004. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
https://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information through
https://www.regulations.gov or email that you consider to be CBI or
otherwise protected. The https://www.regulations.gov website is an
``anonymous access'' system, which means the EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an email comment directly to the EPA without
going through https://www.regulations.gov, your email address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the internet. If you
submit an electronic comment, the EPA recommends that you include your
name and other contact information in the body of your comment and with
any disk or CD-ROM you submit. If the EPA cannot read your comment due
to technical difficulties and cannot contact you for clarification, the
EPA may not be able to consider your comment. Electronic files should
avoid the use of special characters, any form of encryption, and be
free of any defects or viruses.
Docket: All documents in the docket are listed in the https://www.regulations.gov index. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, will be publicly available only in the hard
copy. Publicly available docket materials are available either
electronically in https://www.regulations.gov.
The EPA is temporarily suspending its Docket Center and Regional
Records Centers for public visitors to reduce the risk of transmitting
COVID-19. In addition, many site information repositories are closed
and information in these repositories, including the deletion docket,
has not been updated with hardcopy or electronic media. For further
information and updates on EPA Docket Center services, please visit us
online at https://www.epa.gov/dockets.
The EPA continues to carefully and continuously monitor information
from the Centers for Disease Control and Prevention (CDC), local area
health departments, and our Federal partners so that we can respond
rapidly as conditions change regarding COVID.
FOR FURTHER INFORMATION CONTACT: Jason Gunter, Remedial Project
Manager, U.S. Environmental Protection Agency, Region 7 Office, SEMD/
LMSE, 11201 Renner Boulevard, Lenexa, Kansas 66219; (913) 551-7358;
email: gunter.jason@epa.gov.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Introduction
II. NPL Deletion Criteria
III. Deletion Procedures
IV. Basis for Site Deletion
I. Introduction
The EPA Region 7 is proposing to delete the Annapolis Lead Mine
Superfund Site (Site) from the National Priorities List (NPL) and is
requesting public comment on this proposed action. The NPL constitutes
appendix B of 40 CFR part 300, the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP), which the EPA promulgated
pursuant to section 105 of the Comprehensive Environmental Response,
Compensation and Liability Act (CERCLA) of 1980, as amended. The EPA
maintains the NPL as the list of sites that appear to present a
significant risk to public health, welfare, or the environment. Sites
on the NPL may be the subject of remedial actions financed by the
Hazardous Substance Superfund (Fund). As described in 40 CFR
300.425(e)(3) of the NCP, sites deleted from the NPL remain eligible
for Fund-financed remedial actions if future conditions warrant such
actions.
The EPA will accept comments on the proposal to delete this Site
for thirty (30) days after publication of this document in the Federal
Register.
Section II of this preamble explains the criteria for deleting
sites from the NPL. Section III of this preamble discusses procedures
the EPA is using for this action. Section IV of this preamble discusses
the Site and demonstrates how it meets the deletion criteria.
II. NPL Deletion Criteria
The NCP establishes the criteria the EPA uses to delete sites from
the NPL. In accordance with 40 CFR 300.425(e), sites may be deleted
from the NPL where no further response is appropriate. In making such a
determination pursuant to 40 CFR 300.425(e), the EPA will consider, in
consultation with the state, whether any of the following criteria have
been met:
i. Responsible parties or other persons have implemented all
appropriate response actions required;
ii. All appropriate Fund-financed response under CERCLA has been
implemented, and no further response action by responsible parties is
appropriate; or
iii. The remedial investigation has shown that the release poses no
significant threat to public health or the environment and, therefore,
the taking of remedial measures is not appropriate.
[[Page 41489]]
Pursuant to CERCLA section 121(c) and the NCP, the EPA conducts
Five-Year Reviews (FYRs) to ensure the continued protectiveness of
remedial actions where hazardous substances, pollutants, or
contaminants remain at a site above levels that allow for unlimited use
and unrestricted exposure. The EPA conducts such FYRs even if a site is
deleted from the NPL. The EPA may initiate further action to ensure
continued protectiveness at a deleted site if new information becomes
available that indicates it is appropriate. Whenever there is a
significant release from a site deleted from the NPL, the deleted site
may be restored to the NPL without application of the hazard ranking
system.
III. Deletion Procedures
The following procedures apply to deletion of the Site:
(1) The EPA consulted with the state of Missouri before developing
this Notice of Intent to Delete.
(2) The EPA provided the state of Missouri 30 working days for
review of this document prior to publication of it today.
(3) In accordance with the criteria discussed above, the EPA has
determined that no further response is appropriate.
(4) The state of Missouri, through MDNR, has concurred with
deletion of the Site from the NPL.
(5) Concurrently with the publication of this Notice of Intent to
Delete in the Federal Register, a notice is being published in a major
local newspaper, the Mountain Echo, in Ironton, Missouri. The newspaper
notice announces the 30-day public comment period concerning the Notice
of Intent to Delete the Site from the NPL.
(6) The EPA has placed copies of documents supporting the proposed
deletion in the deletion docket and has made these items available for
public inspection and copying at the Site information repositories
identified above.
If comments on this document are received within the 30-day public
comment period, the EPA will evaluate and respond appropriately to the
comments before making a final decision to delete. If necessary, the
EPA will prepare a Responsiveness Summary to address any significant
public comments received. After the public comment period, if the EPA
determines it is still appropriate to delete the Site, the Regional
Administrator will publish a final Notice of Deletion in the Federal
Register. Public notices, public submissions, and copies of the
Responsiveness Summary, if prepared, will be made available to
interested parties and in the Site information repositories listed
above.
Deletion of a site from the NPL does not itself create, alter, or
revoke any individual's rights or obligations. Deletion of a site from
the NPL does not in any way alter the EPA's right to take enforcement
actions, as appropriate. The NPL is designed primarily for
informational purposes and to assist EPA management. Section
300.425(e)(3) of the NCP states that the deletion of a site from the
NPL does not preclude eligibility for future response actions, should
future conditions warrant such actions.
IV. Basis for Site Deletion
The following information provides the EPA's rationale for deleting
the Site from the NPL:
A. Site Background and History
i. Site Location and Geography
The Site is listed under CERCLIS ID MO0000958611 and is located
east of Annapolis, Iron County, Missouri, on the east side of Iron
County Road (ICR) 138 approximately three eights of one mile north of
Missouri State Highway (Highway) 49. The geographic coordinates of the
Site are latitude 37[deg]21'40'N and longitude 90[deg]40'30' W. The
Site is located on the Des Arc, Missouri Quadrangle 7.5-Minute
Topographic Map in sections 13 and 14, township 31 North, range 3 East.
The Site is situated on relatively rugged terrain that slopes
westward toward Sutton Branch Creek. The Site is largely forested
except for the chat/tailings area, and the road cut for ICR 138. The
land surrounding the Site is predominantly forested, with limited
agricultural production and isolated residential properties within
1,000 meters of the Site.
The Site consists of three operable units (OUs). OU1 is defined as
the Sutton Branch Creek floodplain from the Probable Point of Entry
(PPE) to the confluence with Big Creek and includes the historical
mining area. OU2 is defined as Big Creek from the mouth of Sutton
Branch Creek downstream to the confluence with the St. Francois River,
which is a total of approximately 20 miles of stream. OU3 is defined as
the town of Annapolis.
OU1 includes the historical mining area and the Sutton Branch Creek
Floodplain. The total area of OU1 is approximately 200 acres. Prior to
the removal action, the dominant feature of the Site was a chat/
tailings residue pile that covered approximately 10 acres in the
northern portion of the Site. The pile was composed of grey- to tan-
colored material that resembled fine-grained sand. The material was
highly erodible, resulting in steep-sided features and an outwash area
that fanned westward to Sutton Branch Creek, which flows north to south
on the west side of ICR 138. The chat/tailings residue dominated the
substrate of Sutton Branch Creek for approximately 0.75 mile, where
Sutton Branch Creek merged with Big Creek. Tailings originating at the
Site could be seen as greyish creek bed sediments in Sutton Branch
Creek and in portions of the flood plain.
OU2 includes Big Creek from the confluence with Sutton Branch Creek
to the residential soil in the town of Annapolis. The EPA sampled OU2
in 2006 and 2007 and determined that no remedial action was necessary
to ensure protection of human health and the environment. A No Action
Record of Decision (ROD) for OU2 was issued on June 28, 2007.
OU3 is located in Southern Iron County in the Old Lead Belt of
southeast Missouri. OU3 covers the town of Annapolis. Lead mining
occurred near the town from approximately 1919 to 1940. The EPA signed
a ROD for OU3 on June 29, 2007. The EPA determined that the CERCLA
action necessary for OU3 was to remove lead contamination from the
driveway of one residence. The lead contamination in the property's
driveway exceeded 400 parts per million (ppm), the EPA screening level
for lead. The driveway was removed and taken by dump truck to the
existing lead-contaminated-material repository at OU1. The contaminated
driveway was replaced with uncontaminated gravel. No additional
remedial response action is necessary for OU3.
The Iron County area is within the St. Francois Mountains
Physiographic Province of Missouri. Geologically, this area is
characterized by lower Paleozoic carbonates and siliciclastics
onlapping the Precambrian highland mass. Faults cutting basement and
Paleozoic rocks are responsible for much of the Mississippi Valley-type
mineralization present in the vicinity of the Site. Stratigraphy
associated with completed groundwater wells includes unconsolidated
valley alluvium typically 20-25 feet thick, and the underlying Cambrian
sandstones and dolomites. Cambrian formations within 4 miles of the
Site include, in descending stratigraphic order, Potosi, Derby-Doerun,
Davis, Bonne Terre, and Lamotte. The Potosi Formation is moderately
permeable and is a medium to massively bedded dolomite. The Davis
Formation is comprised of a shale
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and dolomite sequence with low permeability; however, vertical jointing
facilitates localized movement of groundwater. The Bonne Terre
Formation has several facies and lithologic changes and is quite
permeable; it also contains the area's lead deposits. In the vicinity
of the Site, the Bonne Terre Formation rests upon the Precambrian
basement rocks.
On-site soils are mainly dark brown, Midco cherty silt loam,
typically found on 0- to 3-percent slopes downgradient of upland areas.
Typically, the surface layer is dark brown cherty loam approximately 7
inches thick. Below this to a depth of 60 inches or more are brown
strata of very cherty sandy loam and extremely cherty sandy loam. In
some areas, the dark surface layer is more than 10 inches thick.
Excessively drained areas, including sandy soils mainly composed of
chat with gravel bars, are near or in the stream channels. Permeability
is moderately rapid in the Midco soil, and surface water runoff is
slow. The available water capacity is low.
ii. Former Use and History of Contamination
Galena ore (lead-bearing ore) was mined from the Site beginning in
the 1920s. Mining activities continued sporadically until 1940. The
mine had one shaft to 450 feet below the ground surface (BGS) with
several hundred feet of lateral shafts to work the ore bodies. In
addition to mining the ore, various equipment was used on site to crush
and mill the ore to concentrate the lead. Annapolis Lead Company, a
now-defunct company, owned/operated the mine from 1919 to 1931, when
the majority of ore was extracted. Production figures from 1923 to 1931
indicated that approximately 1,173,000 tons of mining waste containing
elevated metals was generated during that time period. The Ozark Lead
Mining Corporation, a now-defunct company, owned the property from 1931
to 1934 but apparently did not conduct mining activities. Basic Metals
Mining Corporation, also now defunct, owned the mine from 1934 to 1941
and conducted mining activities for a short time between 1938 and 1940
(no production figures were located for that time period). Apparently,
no mining occurred on site after that time. American Waste Material
Corporation owned the property for several months in 1942 then sold the
property to H. Hoffman, Fred S. Fuld, and J.J. Rubenstein, who deeded
their rights to St. Joseph Lead Company in 1952. In 1982, St. Joseph
Lead Company sold the surface rights to Larry W. and Oneta Mayberry,
but retained the mineral rights until 1987. The Doe Run Company has
owned the mineral rights from 1987 until present. From 1982 through the
present, the surface rights to various tracts within the Site were
conveyed to several owners.
Site features included numerous former mining operation buildings,
located primarily in the northern portion of the Site. Most of the
buildings have deteriorated to where only foundations are present. An
exception is a single story of a once multi-storied structure near the
center of the Site, which was last used as a residence in 1997. Mining
refuse, including boulder-sized chunks of waste rock, is interspersed
among the former buildings.
iii. Sampling and Removal Activities
MDNR collected sediment and surface water samples near OU1 in
September 1992. The analyses showed sediments in Sutton Branch Creek
contained elevated lead, copper, nickel, and zinc concentrations. Lead
levels in the creek water were near threshold concentrations for safe
drinking water and protection of aquatic life, as established by
Missouri water quality standards at that time. The state of Missouri
conducted no source area sampling of sediment, soil, surface water, or
groundwater.
The EPA's contractor conducted a Screening Site Inspection in June
1996, collecting data primarily on background information, waste and
source sampling, groundwater exposure pathways, surface water exposure
pathways, soil exposure pathways, and air exposure pathways. Results of
this report were documented in the Removal Assessment.
In March 1997, the EPA collected dust and wipe samples from the
then-existing on-site residence, and an X-Ray Flourescence Spectrometer
(XRF) was used to screen surface soils at the Site. Results from these
samples, along with the results from blood-lead samples taken from the
children living at the residence on the Site, were used in making a
determination that individuals living on the Site were being adversely
impacted. In May 1997, the EPA performed a removal action which
resulted in the Iron County Division of Family Services relocating the
children and their immediate family from the Site. The EPA completed an
Expanded Site Inspection and Removal Assessment (ESI/RA) of the
northern segment of the Site in February 1999. Data collected during
the ESI/RA indicated that the Site has had an impact on the
environment, primarily through the surface water pathway.
A removal action was conducted in 2004, as discussed in further
detail below. During this removal action, 152,868 cubic yards of lead-
contaminated soil was excavated and placed in a repository constructed
on site. The repository was capped and vegetated to prevent future
exposure risk. Excavated areas were either backfilled or regraded to
prevent ponding, and vegetated.
iv. NPL Listing
The Site was proposed for listing on the NPL on March 9, 2004 (69
FR 10646). It was listed on the NPL on July 22, 2004 (69 FR 43755) due
to elevated levels of heavy metals, particularly lead, which were
present throughout the Site. In addition, surface water bodies
downstream of the Site contained elevated concentrations of site-
related hazardous substances that could pose a threat to recreational
fisheries and wetlands in the area.
B. Remedial Investigation and Feasibility Study (RI/FS)
i. Scope of Remedial Investigation
The Remedial Investigation (RI), with expanded sections on surface
water, sediments, and soil, was completed in August 2005. The purpose
of the RI was to determine the nature and extent of contamination. A
Hydrology and Flood Plain Report was conducted to evaluate the existing
conditions and behavior of the Sutton Branch Creek flood plain.
The Contaminants of Concern included:
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Soil Sediment Surface water
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Lead..................................... Arsenic..................... Arsenic.
Cadmium.................................. Cadmium..................... Cadmium.
Zinc..................................... Lead........................ Lead.
Zinc........................ Zinc.
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[[Page 41491]]
Based on information collected during the RI along with historical
documentation, four lead-contaminated source areas were delineated for
assessment purposes: The heavily-eroded chat and tailings waste pile,
the outwash area of the chat and tailings waste pile, the former mining
operations area, and the mill slime pond. An estimated 51,677 cubic
yards of lead-contaminated tailings, chat, and soil (above 500 mg/kg)
were calculated for these four areas.
The RI concluded that thousands of cubic yards of mining waste
(tailings) migrated to the Sutton Branch Creek floodplain via the
surface water pathway. Waste management practices likely included
dumping mining waste along a former railroad spur that was located in
the western portion of the Site. To assess the extent of metals-
contaminated soils and sediments at the Site, the EPA conducted an
investigation of Sutton Branch Creek and the soils within its
floodplain. The 100-year floodplain of Sutton Branch Creek contains
elevated lead concentrations, especially in the depositional areas
south of Highway 49.
ii. Ecological Risk Assessment
In August 2005, the EPA prepared a baseline ecological risk
assessment (BERA), which evaluated risk to aquatic and terrestrial
systems at the Site. The BERA addressed risks to aquatic and
terrestrial biota, or animal and plant life, by comparing the maximum
measured concentrations of contaminants of concern (COCs) to ambient
water quality criteria and conservative toxicity criteria.
The EPA determined that the principal threat for OU1 was the
ecological risk to both the aquatic and terrestrial environments.
Living organisms within both ecosystems had elevated exposure to
mining-related metals, and the metals could cause adverse effects on
some receptors in each ecosystem.
iii. Human Health Risk Assessment
In August 2005, the EPA also prepared a baseline Human Health Risk
Assessment (HHRA). The HHRA evaluated current and potential future
risks to human health associated with the presence of heavy metals,
particularly lead, in soils, surface water, sediment, and groundwater
at the Site.
Based on the results of field investigations and the HHRA, the EPA
concluded that surficial lead residual contamination in the mine
operations area was generally below levels of concern for lead;
however, hotspots exist under the 18'' engineered soil cover in limited
areas that could be associated with unacceptable exposures to lead.
Unacceptable exposure could be realized for both future construction
workers and future residents. In addition, lead exposures for
recreational visitors to the floodplain soils could reach unacceptable
levels, but lead exposures for recreational users to surface water and
sediment in Sutton Branch Creek did not appear to cause unacceptable
risk.
In addition, for all other COCs, cancer risks and non-cancer
hazards for recreational exposures in the floodplain and creek fell
within the acceptable risk range for cancer and noncancer hazards.
These results suggested that recreational exposure to COCs other than
lead may be in an acceptable range.
iv. Findings From Feasibility Study
The EPA screened the following alternatives in the Feasibility
Study (FS):
Alternative 1: No Further Action.
Alternative 2: Phosphate Amendment of Flood Plain Soils
with In-Stream Stabilization Techniques and Limited Sediment Removal.
Alternative 3: Excavation of Sediments in Sutton Branch
Creek.
Alternative 4: Excavation of Sediments in Sutton Branch
Creek and Soil Cap.
Alternative 5: Complete Source Removal and On-Site
Disposal.
Alternative 6: Complete Source Removal and Disposal in an
Off-Site Landfill.
After screening the alternatives, the EPA concluded that all of the
action alternatives would result in significant reductions in metal
loadings to surface water from floodplain sources. The EPA selected
Alternative 2 as the preferred remedy for the Site.
C. Selected Remedy
i. Components of the Selected Remedy
The selected remedy for OU1 included the following actions:
Addition of phosphate to floodplain soils (away from the
outer edge of the riparian zone) during the dry season to improve the
density of vegetation and to reduce the bioavailability of lead to
terrestrial receptors.
Mining wastes in heavily forested, thickly vegetated
areas, such as the riparian buffer, will not be subject to excavation,
consolidation, or capping.
Excavation of sediments from Sutton Branch Creek in
pockets, or depositional areas. The amount of excavation will be
determined during the Remedial Design (RD) phase.
Placement of excavated sediments in the existing
repository area and cap with a simple soil cover.
Stabilization of the Sutton Branch Creek channel with
large rock and/or other material to prevent washouts and stream channel
meandering. The extent of stabilization will be determined during the
RD phase.
Implementation of institutional controls.
Performance of annual monitoring to determine remedial
effectiveness The monitoring frequency will be evaluated to determine
whether it should be more frequent or can be extended to periods beyond
annual monitoring.
MDNR will manage post-removal maintenance of the
protective cover consistent with all federal and state laws.
ii. Remedial Action Objectives (RAOs)
1. RAOs for Soils and Source Materials
The RAOs for soils and source materials were based on the findings
of the BERA and HHRA. These RAOs were designed to address the potential
ecological risks associated with direct exposure to COCs in mine and
mill wastes, and in the affected soils surrounding the wastes.
Terrestrial vertebrates, specifically vermivores whose diet consists of
earthworms and other soil-dwelling invertebrates, were identified as
the receptors of concern based on the information from the BERA.
Ecological risks associated with source material erosion (as sediment)
and seepage/runoff were addressed in other RAOs. Due to these findings,
the following RAO was developed:
Limit the exposure of terrestrial biota to COCs in surficial
materials that would potentially result in excessive ecological risks
associated with intake of site COCs.
The human health exposure routes were addressed at much of OU1.
However, surficial contamination in the southern portion of OU1 could
cause unacceptable exposures. Due to this minor risk, the following RAO
was developed:
Limit human ingestion of COCs from on-site soils or source
materials that would potentially result in cancer risks greater than
10-6 (one in one million), non-carcinogenic hazard indexes
greater than 1 (1 or lower means adverse noncancer effects are
unlikely), or unacceptable blood lead levels that present human health
risks.
2. RAOs for Surface Water and Sediment
Aquatic and terrestrial biota are exposed to COCs in surface waters
or
[[Page 41492]]
sediments derived from mill wastes. Site-specific, risk-based
contaminant levels for aquatic biota have not been established for the
Site. However, consensus-based sediment quality guidelines were used as
reference material. Sediment with elevated COC concentrations may pose
risks to benthic, or bottom-level, communities that live and feed in
sediment deposits and benthic feeders that may ingest sediment.
Applicable or relevant and appropriate requirements (ARARs) for
sediments were not developed for the Site, but consensus-based
guidelines can be followed. Based on the discussion presented above, a
surface water RAO and a sediment RAO have been developed. These RAOs
address the interactions between source materials and surface waters
and the potential exposure of aquatic biota to COCs from mill waste.
The surface water and sediment RAOs are as follows:
a. Limit the exposure of aquatic biota to waters contaminated with
COCs in Sutton Branch Creek in excess of chronic and acute Federal
Ambient Water Quality Criteria (AQWC) for such COCs.
b. Limit the risks to aquatic biota by controlling erosion and
transport of lead-contaminated mill wastes and sediments containing
lead-contaminated mill wastes in classified perennial or state-listed
ephemeral streams or rivers.
iii. Explanations of Significant Differences (ESDs)
1. September 9, 2008 Explanation of Significant Differences #1 (ESD #1)
The 2005 OU1 ROD included addition of phosphate to floodplain soils
(away from the outer edge of the riparian zone) during the dry season
to improve the density of vegetation and to reduce the bioavailability
of lead to terrestrial receptors. The significant difference under ESD
#1 was the exclusion of phosphate application as part of the remedy.
Since the signing of the 2005 OU1 ROD, pilot testing of phosphate
application to residential soils was conducted in Region 7 and
reductions in bioavailability were achieved by tilling phosphoric acid
into the soil. A second finding of the pilot testing was that surface
application of fertilizer-grade phosphate was ineffective in reducing
bioavailability. This meant that to have an impact upon
bioavailability, phosphoric acid would have to be tilled into the lead-
contaminated riparian areas.
A vegetative cover reduces the potential for human exposure to lead
in soils under the vegetation. Tilling up the established vegetation
would, for at least the short term, increase the exposure potential to
lead in such soils until regrowth of the vegetative cover. The efficacy
of applying the phosphate fertilizer to the riparian areas as described
in the ROD was reevaluated. The EPA, in consultation with MDNR, made
the decision to leave the vegetation in place and omit the phosphate
treatment because (1) the current vegetative cover was sufficient and
removing it could cause more harm than good, and (2) surface
application of phosphate fertilizer would not result in significant
reductions in bioavailability of the lead in the target soils/
sediments.
2. May 29, 2019 Explanation of Significant Differences #2 (ESD #2)
The 2005 OU1 ROD's selected alternative regarding institutional
controls provided for the imposition of restrictive covenants or
easements. The EPA determined that the voluntary environmental
covenants described in the 2005 OU1 ROD were not obtainable due to
property owners refusing to sign and record the environmental
covenants. Therefore, the EPA determined that an alternative to
environmental covenants was required. Under ESD #2, the EPA could
record notices of contamination for each tract of contaminated land
that did not have an environmental covenant.
The use of a notice of contamination differs significantly from the
use of an environmental covenant described in the ROD. An environmental
covenant can prohibit certain uses of a property and can also require
that certain actions be taken, thus achieving all the ROD's objectives.
A notice of contamination cannot prohibit or mandate certain uses or
actions and only provides information that may inform human behavior. A
notice of contamination may be effective in achieving the ROD's
objectives of providing notice to prospective purchasers and occupants
that there may be contaminants in the subsurface soils and groundwater
and ensuring that future owners are aware of engineered controls put
into place as part of the Site's remedial action and under the prior
removal action. Thus, by recording a notice of contamination with the
Iron County recorder of deeds office, the goals of minimizing exposures
to contamination remaining at OU1 and limiting the possibility of the
spread of contamination may be achieved. The EPA also will conduct
annual reviews of the deeds to ensure that the notices remain in
effect.
In addition to the filing of notices of contamination, the EPA will
conduct reviews every five years of the protectiveness of the remedy as
required by section 121(c) of CERCLA. During these reviews, the EPA
will again engage the owners of all properties where the notices of
contamination have been recorded and attempt to gain landowner consent
to the use of an environmental covenant. For properties that have been
conveyed to new owners, the EPA will engage those new owners to
determine whether they will agree to the use of environmental
covenants. Due to the current impossibility of placing environmental
covenants on all affected properties, the EPA determined that this is
the most prudent and protective manner to address land use.
D. Response Actions
i. Removal Action
In September 2003, the EPA proposed a time-critical removal action
for the Site. The goal of the removal action was to identify,
consolidate, and stabilize the lead-contaminated waste mine tailings on
site. The time-critical removal action work began at the Site in May
2004. When the removal action began at the Site, settling basins were
constructed to manage storm water runoff. Earth-moving equipment was
used to form the tailings and contaminated soil into a mound in the
middle of the ravine where the pile was originally located. All areas
in the tailings pile vicinity that had a mean lead surface
concentration greater than 1,000 ppm were delineated and excavated.
Excavations proceeded to the lesser of a depth of 18 inches or until a
lead level below 400 ppm was achieved. All excavated areas were
backfilled with clean material (<240 ppm lead) and excavated soil was
consolidated into the on-site tailings pile. The tailings pile was
graded and compacted with an engineered protective cover installed over
the tailings. The protective cover consists of uncontaminated clay and
topsoil, allowing for the establishment of vegetative cover.
ii. Remedial Action
The RI determined that additional actions were required after the
completion of the Removal Action. The EPA developed the RD, which was
reviewed by MDNR and approved by the EPA on June 14, 2007. Remedial
action (RA) on-site construction commenced on July 25, 2007.
The following paragraphs describe the specific components of the
selected remedy.
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1. Erosion Work Around the Repository and the Historical Mining Area
This included the area around the former mining area containing
significant erosion. Work in this area was required to protect the
integrity of the existing soil repository and to prevent further runoff
into Sutton Branch Creek. The specific areas of work included the
following:
Point of Entry (POE) Area: Work at the POE Area included
constructing the channel between the repository and the settling basin.
Borrow Area: The Borrow Area was a major erosional area.
It was stabilized to minimize future erosion. This included regrading,
placement of rock for cover/erosion control, and diverting potential
runoff around this area through channelization.
North Area Erosion: This area was stabilized with rock to
minimize future erosion.
North Hillside Erosion: This area was regraded and
stabilized with rock to minimize future erosion.
North Lower Erosion: This area was regraded, covered with
rock, and two benches were constructed to slow the water entering the
Site.
Repository Drainage Extension: This area consisted of an
extension of the rock drainage around the perimeter of the existing
repository, along with a 6-foot rock blanket around the inside
perimeter of the drainage channel.
2. Additional Blanket on Northeast Side
This area required regrading and a rock blanket on the northeast
side.
3. Removal and Disposal of Sediment/Soil
The selected remedy included excavation and vacuum dredging of
contaminated sediment from Sutton Branch Creek. Contaminated sediment
in the depositional areas (pools) was removed to reduce the potential
of downstream migration of contaminated sediment. Approximately 500
cubic yards (yd\3\) of contaminated sediment required removal.
The contaminated sediment was removed until the natural substrate
was uncovered. The banks of excavated areas were stabilized as needed.
To minimize disturbance of the natural substrate, the EPA used the most
non-invasive technique to remove the fine sediment. The specific areas
that required removal are:
POE Area: This included the area where the mine runoff
historically entered Sutton Branch Creek. The EPA removed approximately
115 yd\3\ of sediment/floodplain soil and placed approximately 100
yd\3\ of riprap to achieve stability. The removed sediment/soil was
placed in the new repository cell.
Sycamore Tree Area: This included the area of Sutton
Branch Creek where a sycamore tree caused the east stream bank to
erode. This tree was removed, and the east bank was stabilized. The EPA
removed approximately 135 yd\3\ of sediment/floodplain soil and placed
approximately 100 yd\3\ of riprap to achieve stability. The removed
sediment/soil was placed in the new repository cell.
Beaver Dam Area: This included the area of Sutton Branch
Creek where a breached beaver dam was trapping sediment. The remnants
of the beaver dam were removed along with the sediment on the east and
west banks and in the channel. The EPA removed approximately 185 yd\3\
of sediment/floodplain soil and placed approximately 60 yd\3\ of riprap
for stabilization. The removed sediment/soil was placed in the new
repository cell.
Bridge Area: This was the furthest downstream section
(furthest southern point) of the project. This section required two
separate removals: One preceding the other stream work and one
following the other stream work. During the first stage, approximately
40 yd\3\ of sediment was removed from the large hole under the bridge
using vacuum dredging and placed in the new repository cell. During the
second stage, approximately 30 yd\3\ of sediment was removed and placed
in the new repository cell.
An on-site repository exists for disposal of the excavated
sediment. Approximately 500 yd\3\ of sediment was placed in the
repository. The existing repository is located on the historical mine
waste pile. The repository was constructed so that the contaminated
sediment could be placed on the south side of the repository, thus
greatly reducing the distance for contaminant transport. The new cell
on the repository required approximately 300 yd\3\ of clean fill to be
placed on top of the contaminated sediment. The top 12 inches of this
fill met the soil criteria in RD specifications and was properly
graded, stabilized with jute mat, and vegetated using the criteria in
the RD specifications. The vegetative cover has been inspected
biannually since 2007 and has provided adequate erosion control.
Final inspection of the Site by the EPA and MDNR concluded that the
soils RA had been conducted and completed in accordance with the soils
RD plans and specifications; a punch list of additional work items was
not needed. The remedy was complete with approval of the Final Closeout
Report by the EPA and MDNR in September 2007.
E. Cleanup Levels
After the RA construction was complete, the EPA began monitoring
sediment, surface water, and macroinvertebrates in Sutton Branch Creek
and Big Creek. This sampling was conducted biannually (each fall and
spring) from 2007-2011 and was reduced to one sampling event during the
second FYR, which occurred in July 2017. Sampling occurred at five
different sites along Sutton Branch Creek and Big Creek. Data was
collected for the following analytes in sediment and surface water:
Arsenic, cadmium, cobalt, copper, lead, nickel, and zinc.
A historic flooding event occurred in the greater Annapolis,
Missouri, area on April 28-30, 2017. This flooding event dumped upwards
of 15 inches of rain in a short period of time, resulting in widespread
flooding. Numerous roads, bridges, and buildings were destroyed. Many
roads were flooded through the event, including Highway 49 in Iron
County. Several rivers reached major and historic levels. The U.S.
Geological Survey Stream Gage #07037300 is located approximately 20
river miles downstream of the Site on Big Creek. The mean daily
discharge at this gage from 2006 through 2016 was 272 cubic feet per
second (cfs). The highest peak flow from 2006 through 2016 was 23,800
cfs, which occurred on March 18, 2008. In late April of 2017, during
the record-breaking flood, the gage recorded a peak flow of 17,400 cfs
on April 29, and a peak flow of 27,500 cfs on April 30. The discharge
on April 30 was the highest event ever recorded since the gage has been
in operation, which began in 2006.
Post-flooding site inspections indicated that the flooding event
washed chat tailings from the floodplain into Sutton Branch Creek and
depositional areas around sampling site 3 (Sutton Branch Creek 500 feet
downstream of the Highway 49 bridge). During the RA, the pool located
below the Highway 49 bridge was remediated using excavation as well as
a vacuum truck. This is a major depositional area. The EPA and MDNR
have visually monitored this area two times per year. Over the last ten
years, the lead concentration at sampling site 3 has been elevated;
however, the lead levels that were discovered (2,840 ppm) after the
large flood in April 2017 exceeded the lead levels that were found
prior to remediation. The EPA and MDNR have continued to monitor this
area along
[[Page 41494]]
with sampling site 5 (mouth of Sutton Branch Creek at confluence with
Big Creek) to determine whether this is having an impact on Big Creek.
The most recent sampling event was conducted on February 14, 2019, and
the results for each sampling station are as follows:
Sampling Site 3 (Sutton Branch Creek south of Highway 49
Bridge)--438 ppm lead
Sampling Site 5 (Mouth of Sutton Branch Creek at confluence
with Big Creek)--19 ppm lead
As seen in the most recent data set, sediment concentrations
continue to decline at the monitoring stations. The EPA will continue
to monitor these areas as part of the FYRs. Corrective measures may be
taken if the levels do not continue to decrease over time.
F. Operation and Maintenance
i. Ongoing and Completed Operation and Maintenance
Approximately one month after construction, the EPA and MDNR
inspected the Site to observe the condition of the cap, identify any
erosional features, and assess the success of each remedial component.
After inspection, the EPA and MDNR considered each of these areas
construction complete, although several areas were identified where
improvement was required. One major issue was the concern that erosion
would occur where vegetation was not established. Therefore, the EPA
and MDNR focused the majority of their efforts on revegetating the Site
in 2008. Approximately 1,015 trees were planted, along with a site-
specific seed mix, to help stabilize the Site. Additionally, the EPA
and MDNR performed inspections every six months along with monitoring
and maintenance activities. Some of the trees that were planted are now
over 25 feet tall and the improved vegetation has stabilized the slopes
and decreased sediment accumulation in the settling basin.
During the reporting period for the second FYR, one major area of
concern was the north repository drainage channel. During high water
events, the water would occasionally overflow the existing channel onto
the surrounding area instead of down to the settling basin. Due to the
concern of the water flowing out of the channel, MDNR performed
maintenance activities in October 2012. MDNR modified the north
repository drainage channel as well as the channel below the repository
downgradient to the settling basin. he large rock that had been placed
in the channel was pulled out to the channel edges. The filter rock was
left in place within the channel. The goal was to allow additional flow
through the channel down to the settling basin during high water
events. The report of these activities is included in the second FYR.
In June 2013, MDNR performed maintenance activities to repair a leak in
the outlet pipe in the settling basin. The report of these activities
is included in the second FYR.
During the reporting period for the third FYR, the northeast branch
of the drainage channel around the tailings pile that washed out was
repaired. MDNR developed engineered designs to repair the channel and
construct a detention pond dam to reduce the flow velocity in the
channel during high rainfall events. MDNR hired a contractor to perform
the repairs. The contractor finished the repairs in April 2019.
ii. Institutional Controls
Under the selected remedy, the EPA required implementation of
institutional controls at properties where elevated lead concentrations
remain on site. The EPA determined that 13 parcels were subject to the
institutional controls. Two different mechanisms were used as part of
the Site's Institutional Control Plan: Environmental covenants and
notices of contamination. On May 21, 2019, one of the 13 property
owners recorded an environmental covenant with the Iron County Recorder
of Deeds. On August 29, 2019, the EPA recorded notices of contamination
regarding the 12 remaining properties with the Iron County Recorder of
Deeds.
As discussed in depth above, the use of a notice of contamination
differs significantly from the use of an environmental covenant
described in the ROD, but still may be effective in achieving the ROD's
objectives. Therefore, as documented in 2019, the EPA issued ESD #2
that provided for the EPA to record notices of contamination instead of
entering into environmental covenants at the contaminated properties.
The EPA also will conduct annual reviews of the deeds to ensure that
the notices remain in effect.
In addition to the filing of notices of contamination, the EPA will
conduct reviews every five years of the protectiveness of the remedy as
required by section 121(c) of CERCLA. During these reviews, the EPA
will again engage the owners of all properties where the notices of
contamination have been recorded and attempt to gain landowner consent
to the use of an environmental covenant. For properties that have been
conveyed to new owners, the EPA will engage those new owners to
determine whether they will agree to the use of environmental
covenants.
G. Five-Year Reviews
Statutory FYRs are required for the Site due to the fact that
hazardous substances, pollutants, or contaminants remain at the Site
above levels that allow for unlimited use and unrestricted exposure.
Two FYRs have been conducted at the Site, the most recent being the
Second FYR, which was completed on September 29, 2017. The
protectiveness determination was Short-term Protective, and included
the following protectiveness statement: The remedy currently protects
human health and the environment because soils and sediments with
elevated lead levels have been excavated or capped and no unacceptable
exposures are occurring. In order to be protective in the long term, to
reduce the potential for future risk, ongoing pursuit of the
[institutional control]s must occur along with routine Operation and
Maintenance indicative of an engineered soil cover. In order for the
remedy to be protective in the long term, [institutional control]s
should be implemented. Additional routine maintenance of the eroded
areas around the repository should be implemented to prevent future
exposure.
Issues from the Second FYR included the following:
Institutional Controls had not been implemented. The
recommendation was to implement the institutional controls by 7/31/
2018. Please note: The EPA implemented institutional controls on 9/13/
2019.
During the reporting period for the Second FYR,
significant erosion had formed on the north end of the repository
drainage channel. The recommendation was to repair the drainage channel
by 7/31/2018. Please note: MDNR repaired the area in April 2019.
A small amount of lead-contaminated sediment (less than 60
cubic yards) was deposited below the Highway 49 bridge in the pool that
was excavated during the RA after the large flood in April 2017. The
EPA and MDNR will continue to monitor this area along with the mouth of
Sutton Branch Creek from 2018 to 2021. If this area continues to be
elevated with COCs, further action may be taken to remove the sediment
from the pool above sampling site 3. As these levels have significantly
declined, no response is anticipated. Please note: This will be
assessed during the third FYR.
[[Page 41495]]
H. Community Involvement
Before and during the RAs, the EPA held multiple public meetings on
site. The EPA has updated the public regarding the FYRs by placing ads
in the local newspaper, as well as updating the local information
repository and the Site's web page. Community involvement activities
associated with the deletion will include making the notice of intent
to delete available for public comment. In addition, the Region 7
Superfund Records Management Service Center will construct a special
document collection that will include the listed document IDs for the
deletion docket documents. This collection will be available for public
review and is located on the Site's web page and the Regulations.gov
website.
I. Determination That the Site Meets the Criteria for Deletion in the
NCP
In accordance with 40 CFR 300.425(e), EPA Region 7 finds that the
Annapolis Lead Mine Site (the subject of this deletion action) meets
the substantive criteria for deletion from the NPL. The EPA has
consulted with and has the concurrence of the state of Missouri. All
appropriate Fund-financed response under CERCLA was implemented, and no
further response action by responsible parties is appropriate.
The implemented remedy at the Site has achieved the degree of
cleanup specified in the ROD for all pathways of exposure. All selected
RA objectives and associated cleanup levels are consistent with agency
policy and guidance. No further Superfund response is needed to protect
human health and the environment.
List of Subjects in 40 CFR Part 300
Environmental protection, Air pollution control, Chemicals,
Hazardous substances, Hazardous waste, Intergovernmental relations,
Penalties, Reporting and recordkeeping requirements, Superfund, Water
pollution control, Water supply.
Authority: 33 U.S.C. 1251 et seq.
Dated: July 2, 2020.
James Gulliford,
Regional Administrator, Region 7.
[FR Doc. 2020-14912 Filed 7-9-20; 8:45 am]
BILLING CODE 6560-50-P