ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY
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&EPA
United States
Environmental Protection
Agency
Henry's Knob Site Case Study
Revitalizing Mine Tailings in Clover,
South Carolina
This case study highlights ecological revitalization outcomes at the Henry's
Knob Superfund Alternative Approach1 site in York County, South Carolina.
Working with state and federal regulatory agencies, ABB Inc., (ABB), a
proactive responsible party is using an adaptive management approach to
address environmental impacts from decades of kyanite mining.
From 1947 to 1965, Commercialores, Inc. of New York (Commercialores)
operated and mined the 185-acre Henry Knob area for kyanite. Open pit
mining in a large pit quarry took place on top of the knob or mountain.
Mined ore-grade rock was ground up followed by a floatation process to
liberate the kyanite from the other minerals in the ore. Leftover ground-
up waste rock and spoils, called tailings, were dewatered in ponds and
piles, in accordance with acceptable practices, were left on site. In 1970,
Combustion Engineering, Inc. (CE) merged with Commercialores, and in
1990, ABB acquired CE, and the environmental legacy associated with the
mine property.
During site investigations, EPA and ABB identified an opportunity to
mitigate on-going erosion of the m ine tailings and minimize the potential for
further impacts to groundwater and nearby streams from acid mine drainage.
With approval from EPA and the South Carolina Department of Health and
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Figure 1. Henry's Knob in 1941 (left) prior to mining and Henry's Knob in 1981
after mining (right). (Source: ABB Inc.)
l.The Superfund Alternative Approach uses the same investigation and cleanup process
and standards that are used for sites listed on the National Priorities List (NPL).
https://www.epa.gov/enforcenient/superfund-altemative-approach
This case study is part of a
series focused on ecological
revitalization as part of
contaminated site remediation
and reuse; these case
studies are being compiled
by the U.S. Environmental
Protection Agency (EPA)
Technology Innovation and
Field Services Division
(TIFSD). The purpose of these
case studies is to provide
site managers with ecological
reuse information, including
principles for implementation,
recommendations based
on personal experiences, a
specific point of contact and
a network of sites with an
ecological reuse component.
s		\
Topics Highlighted in
this Case Study:
•	Ecological Revitalization
•	Greener Cleanups
•	Mine Tailing
Revegetation
•	Native Plants Plantings
•	Wildlife and Pollinator
Habitat

Ecological
Revitalization
Ecological revitalization is
the process of returning land
from a contaminated state to
one that supports functioning
and sustainable habitat.
WJ
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December 2017 EPA-542-R-18-001	www,clu-in. ore/ecotools

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ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY
Environmental Control (SCDHEC), ABB took an adaptive
management approach to addressing these issues. This
approach consists of the implementation of media-specific
remedies in steps and evaluated for effectiveness.2 As the
first step in the adaptive management remedy approach, ABB
is in the process of revegetating former mine tailings areas.
The vegetation reduces the erosion of the tailing and reduces
infiltration of water through the tailings thus reducing the
generation of acid mine drainage as a source of impact to
groundwater and nearby streams. Ongoing monitoring will
evaluate the effectiveness and other benefits associated with
the revegetation. Based on this evaluation implementation of a
groundwater remedy may or may not be necessary. The site's
final cleanup plan, which may incorporate the revegetation
work completed, is under development and will take at least
two years to complete. Figure 1 shows Henry's Knob before
and after mining activities occurred.
Background
The 185-acre site is located near the intersection of Highway
55 and Henry's Knob Road in Clover, York County, South
Carolina. The site is located in a highly mineralized zone
of the Piedmont Province. The Piedmont is characterized
by rolling hills, complex geology and clay-like moderately
fertile soils. The site includes a 7-acre former open pit mine,
tailings pond, spoils piles and remnant mine operations. In
the 1950s and 1960s, Commercial ores mined the site for
kyanite (see text box). During the mining process, waste rock
and spoils were dewatered in ponds and piles.
Acid mine drainage and acid rock drainage impacted surface
areas, surface water and groundwater. Acid mine drainage
is a common environmental impact at former mining sites.
It occurs where iron sulfide minerals (principally pyrite)
are present and exposed to water and oxygen (e.g., the
atmosphere). Weathering of iron sulfides results in acidic
water (low pH) and high concentrations of dissolved iron
and sulfate. Acidic waters promote the weathering of other
rock forming minerals. Similar acid weathering conditions
occur in the absence of mining operations from the oxidation
of pyrite from in-place bedrock. This occurs most notably at
and between the water table and land surface.
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Figure 2. Aerial photo of Henry's Kriob in 2012 prior to
revegetation (Source: ABB Inc.)
Kyanite
A mineral used in producing refractory,
ceramic and porcelain materials that
withstands high temperatures.
Mining Waste
During mining efforts, waste is generated
in the form of overburden, waste rock,
tailings, slags and chat. These materials
are generally acidic and have high
concentrations of metals. Their properties
make them difficult to vegetate, allowing
erosion from natural processes such as
wind and surface water runoff (for example,
rainfall).
2. The Berm/Dam Stability and Surface Water Controls Time Critical Removal Action Memo outlines the site management approach.
This approach is also discussed in the Response to USEPA Comments on the Regional and Telescoped Groundwater Modeling Report.
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ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY
Manganese and cobalt are the primary constituents that
have been identified in groundwater.3
To facilitate the cleanup of the site, ABB recently purchased
the site's main tailings areas from a private owner. Another
property owner owns Henry's Knob, the top of the mountain.
Initial Response
The site is being cleaned up using the Superfund
Alternative Approach (EPA ID: SCN000407376). This
EPA approach uses the same investigation and cleanup
process and standards used for sites on the Superfund
program's National Priorities List (NPL). The approach
is an alternative to listing a site on the NPL; it is not an
alternative to Superfund or the Superfund process.
In 2004, EPA and ABB signed an Administrative Order on
Consent for the site's remedial investigation and feasibility
study (RI/FS). The RI/FS identifies the extent and location
of contamination and cleanup options. EPA and SCDHEC
provide oversight for ABB's activities. Figure 2 shows an
aerial photo of the Site in 2012.
EPA identified 10 Areas of Concern (AOCs) at the site as
well as several off-site residences where contamination
(primarily manganese and/or cobalt) was found in wells.
The 10 AOCs are shown in Figure 3 and listed below:
AOC 1 - West Tailing Pond (industrial waste lagoon
on western side of Henry's Knob Road)
AOC 2 - North Tailings Pond (infiltration beds/settling
ponds on eastern side of Henry's Knob Road)
AOC 3 - Former Mill Operation Buildings (eastern
side of Henry's Knob Road)
AOC 4 - Mine Pit Pond
AOC 5 - East Tailings Pond (also known as Mine
Tailings Area)
AOC 6 - South Fork of Crowder's Creek
AOC 7 - Dumping Area (eastern side of Henry's Knob
Road)
AOC 8 - Northern Waste Rock Area
AOC 9 - Southern Waste Rock Area
AOC 10 - Site Groundwater
3. Publicly available documents and data related to the site are located at: http://www.lienrvsknoben\ironnientalfomm. corn/community
Timeline
1950s and 1980s: Mining
operations active on site conducted
by Commercialores.
1965: Mining operations cease.
1970: Combustion Engineering, Inc.
(CE) merged with Commercialores.
1990: ABB acquires CE
2004: ABB signs agreement with
EPA, agrees to investigate the site
and identify cleanup options. Rl/
FS begins.
2013: Pilot study takes place for
revegetation of mine tailings.
2015: Revegetation of Former Mill
Operation Buildings AOC 3.
2016: Revegetation of West Tailing
Pond AOC 1.
2017: Revegetation of North
Tailings Pond AOC 2.
2017-2018; Revegetation of East
Tailings Pond AOC 5.
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ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY
Figure 3: Henry's Knob Site Map
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2.000 Feet
I i Approximate Areas of Concern
NORTH
Sources: Esri, DigitalGlobe, GeoEye, Earthstar Geographies, CNES/Airbus DS, USD A,
USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, the GIS User Community,
DeLorme, AND, AMEC Environmental & Infrastructure, Inc. and ABB Inc.
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ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY
Initial Cleanup Lfforts
Groundwater
Though the final groundwater remedy will be evaluated
in a FS and documented in a Record of Decision,
ABB and EPA began implementing a residential
well treatment system in 2013 because some nearby
residents were using groundwater. As of 2017, 15
residential well treatment systems are in place.
Mine Tailings
Prior to completion of the RI/FS, ABB expressed
interest in investigating innovative remedies for
the site, including revegetating tailings areas. The
tailings areas had been barren for years Tailings had
historically eroded onto Highway 55 during major
storms and generated clouds of dust during windy
periods. Vegetating these areas would improve their
appearance and reduced erosion from wind and
water. An evaluation will be conducted to determine
if the initial measures result in improvements to
downgradient surface and groundwater quality.
The mine tailings consist of pulverized rock (mostly
silica sand), with an organic carbon content of 0%
and a pH of 2-2.5 standard units. The site's human
health risk assessment (2011) and ecological risk
assessment (2011) found no unacceptable risks
associated with exposure to the mine tailings. The
goals of the revegetation effort were to:
1.	Increase pH and organic carbon content of
the shallow tailings to support the growth of
vegetation.
2.	Reduce the amount of water that infiltrates and
percolates through the tailings.
3.	Mitigate erosion of the tailings.
4.	Mitigate the tailings as an acid mine drainage
source to groundwater and surface water.
Adaptive Management
Approach
An "adaptive management" approach is
one wherein media-specific actions are
implemented in steps within a structured plan
and evaluated using performance metrics
and success criteria. For the Henry Knob
Site, remedial measures for stabilization
of the impoundment dams, revegetation of
the mine tailings, and control of stormwater
water run on/off tailings (source control) are
being implemented first and evaluated for
improvements to downgradient surface and
groundwater quality. Based on this evaluation
implementation of a groundwater remedy
may or may not be necessary. This step-wise,
"adaptive management", approach is being
used to design and implement technically
appropriate, and cost-effective remedial
actions.
Ridge and Furrow
Figure 4. Differences in vegetation growth across the Ridge and Furrow test plot (left), the Standard Farming test plot
(middle) and the vendor test plot (right) in April 2015. {Source: ABB Inc.)
Standard Farming
Vendor
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ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY
Following approval from EPA and SCDHEC, ABB
consulted with local farmers as well as companies
and experts that specialize in revegetation for
guidance and recommendations. The responsible
party also led several studies to create a soil profile
with a sufficient organic content and pH that could
support plant growth across the site's mine tailing
areas. These studies included three test plots within
AOC 1 - the Ridge and Furrow test plot, the Standard
Farming test plot, and a test plot that tested some
specific vendor provided amendments. The Standard
Farming test plot was based on basic farming
practices that incorporates organic materials and
fertilizer into the upper portion of the mine tailings
to create a soil material suitable for the establishment
and sustainable growth of vegetation. Figure 4
shows differences in growth among the three tests
plots. They demonstrate that the addition of organic
material increases vegetation success.
During the two-year study (from 2013 until 2015),
substantial growth was observed on the Standard
Farming test plot. The community welcomed the
study findings. Some community members stopped
in the field office to compliment the appearance of
the vegetated tailing.
The responsible party then took a series of steps to
prepare the site wide mine tailings for vegetation,
including AOC's 1, 2, 3 and 5.
1.	Clearing, grubbing and regrading the proposed
vegetative cover areas.
2.	Performing initial disking and tilling of tailings.
3.	Applying and incorporating locally sourced
mulch hay.
4.	Applying and incorporating locally sourced
sustainably manufactured organic compost.
5.	Applying and incorporating hydrated lime and
agricultural limestone.
6.	Applying and incorporating a water retention
agent.
7.	Applying fertilizer.
8.	Applying seed, wheat straw and tackifier.
9.	Restoring all other disturbed areas.
Use of Local Materials
ABB used locally available materials when
possible, including hay mulch, organic food
and plant based compost, native seeds and
rip-rap for stabilization of drainage channels
and dam faces.
-
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Native Pollinators
Native pollinators provide a significant
amount of America's food supply,
contribute to the economy and perform
key roles in ecosystems. By helping to
keep plant communities healthy and able
to reproduce naturally, native pollinators
assist plants in providing food and cover
for wildlife, preventing erosion and
keeping waterways clean.
Source: http://www.plants.usda.gov/
pollinators/Native Pollinators.pdf
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Ecoiogicai Revitalization
The local cooperative extension, EPA and SCDHEC
also helped the responsible party add a pollinator
seed mix to the original pilot study mix that would
both establish native plants and support pollinators
for all plantings. Native vegetation and pollinator
habitat are now well established on the tailings areas
of the site; all of the tailing areas will be vegetated by
the mid-2018. Figure 5 shows before and after photos
of revegetation on AOC 3.
Both vegetative cover and pollinator seed mixes are
shown in Table 1 and Table 2 respectively.
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ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY
Figure 5. AOC 3 Vegetative Cover before construction (top row, 2014) and after construction (bottom row, 2016). (Source:
ABB Inc.)
Table 1: Vegetative Cover Seed Mix
Scientific Name
Common Name
Cynodon dactylori
Common Bermuda grass
Trifolium spp.
Clovers (Native Mix)
Setaria italica
Foxtail Millet
Schizachyrium scoparium (an-
dropogon scoparius)
Little Bluestem
Bromus cathartic us
Rescuegrass
Panicum virgatum L. (virgatum)
Switchgrass
Lolium arundinaceum
Tall Fescue (KY31)
Eragrostis curvula
Weeping Lovegrass
Notes:Source: ABB Inc.
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ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY
Table 2: Pollinator Seed Mix
Scientific Name
Common Name
Bidens aristosa
Bidens
Chamaecrista fasciculata
Partridge Pea
Coreopsis lariceolata
Lance Leaf Tickseed
Gaillardia pulchella
Indian Blanket
Achillea millefolium
Common Yarrow
Rudbeckia hirta
Blackeyed Susan
Echinacea purpurea
Coneflower
Senna hebecarpa
Wild Senna
Helianthus angustifolius
Swamp Sunflower
Helianthus maximilianii
Maximilian's Sunflower
Verbena hastata
Blue Vervain
Asclepias tuberosa
Butterfly Weed
Monarda punctata
Spotted Beebalm
Symphyotrichum pilosum
Heather Aster
Notes:Source: ABB Inc.
The native vegetation on site attracts a variety of pollinator species, including bees, wasps, butterflies and
birds. Blue Vervain, for example, attracts a variety of bees and birds, including Cardinals, Swamp Sparrows,
Field Sparrows, Eucerine Miner Bees, Halictid Bees and the Verbena Bee.4
By the spring of 2017, vegetative cover had been planted on three AOCs - the West Tailing Pond (AOC 1),
North Tailings Pond (AOC 2), and the Former Mill Operation Buildings (AOC 3). Grasses in some places
reached over five feet high, with a 1-foot-deep root ball. Red-tailed hawks, deer, turkey, frogs, birds and turkey
vultures are regular visitors to the site. Figure 6 shows photos of wildlife on site. Currently, the vegetation will
be maintained for aesthetic beauty and wildlife habitat. In the future, the vegetated areas could be a wildlife
conservation area or community park. In all cases, the vegetation on the tailings areas will remain, helping to
protect public health and the environment.
8
4.USDA plant fact sheet on Blue Vervain: https://plants.usda.gov/factsheet/pdf/fs veha2.pdf.
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ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY
Lessons Learned
1.	Consider revitalization options early in the cleanup process.
At the Henry's Knob site, these discussions enabled an adaptive management approach and allowed
the revegetation effort to be conducted as part of a pilot under the RI/FS process. Revegetation of the
mining tailings piles has mitigated the erosion of tailings and the infiltration of precipitation while
also providing a more visually appealing landscape for the community and ecosystem services.
2.	Use local knowledge and materials when possible.
Discussions with local fanners identified sustainable farming methods and locally sourced
materials that could be useful in revegetating the tailings. The test plot utilized locally sourced
organic materials incorporated into the existing tailings and was the most successful at growing
vegetation. This knowledge was invaluable in making the vegetation process successful.
3.	Consider new cleanup ideas as well as traditional options.
Most mine tailings are remediated by capping them in place, restricting access or consolidating
them in a repository. At the Henry's Knob site, the responsible party identified a viable
alternative - revegetation - and was willing to conduct pilot studies to determine its feasibility.
4.	Purchase available materials locally.
The responsible parties worked to find local materials to support the revegetation efforts. Sourcing
materials locally resulted in money being spent locally on products produced in the nearby community
and reduced costs and emissions associated with long-distance transportation. Working with local
resources also helped identify and incorporate the native seed species into the vegetation efforts.
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ECOLOGICAL REVITALIZATION OF CONTAMINATED SITES CASE STUDY
Additional Resources and References
EPA Site Profile Page:
www, epa. gov/ superfund/henrvs-knob
EPA Site Cleanup Summary:
https://cumulis.epa. gov/supercpad/siteProfiles/index.cfm?fuseaction=second.CleanupActs&id=0407376
Henry's Knob Environmental Investigation Resource:
http://www.henrvsktiobenvironmentalfoaim.com
Berm/Dam Stability and Surface Water Controls Time Critical Removal Action. Henry's Knob Former
Mine Site. AM EC Foster Wheeler Environmental & Infrastructure, Inc. November 19, 2014.
Construction Completion Report. AOC 1 Vegetative Cover Study Test Plot. Henry's Knob Former Mine
site. AMEC Environmental & Infrastructure, Inc. on behalf of ABB Inc. December 13, 2013.
Final Baseline Ecological Risk Assessment. Henry's Knob Former Mine site. York County, South
Carolina. Prepared for ABB Inc. by MACTEC Engineering and Consulting, Inc. June 21, 2011.
Final Field Study Work Plan. Henry's Knob Former Mine site. AMEC Environmental & Infrastructure,
Inc. on behalf of ABB Inc. May 24, 2013.
Final Human Health Risk Assessment. Henry's Knob Former Mine site. York County, South Carolina.
Prepared for ABB Inc. by MACTEC Engineering and Consulting, Inc. June 21, 2011.
Response to USEPA Comments on the Regional and Telescoped Groundwater Modeling Report. Henry's
Knob Former Mine Site.
Revised Vegetative Cover Pilot Study Work Plan. Henry's Knob Former Mine site. AMEC Environmental
& Infrastructure, Inc. on behalf of ABB Inc. August 29, 2013.
Contact Information
Jeffery Crowley
EPA Region 4
Remedial Project Manager
(404) 562-8827
crowlev.iefferv@epa.pov
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