DERR-2024-007873

RECORD OF DECISION
KENNECOTT SOUTH ZONE, OPERABLE UNIT 2
SOUTHWEST JORDAN RIVER VALLEY GROUND WATER PLUM~S
U. S. Environmental Protection .Agency, Region VIII
Utah Department of Environmental Quality
December.13, 2000
TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
DECLARATION
DECISION SUMMARY
PART 1:
PART 2:
A~
B.
C
" D~,
E.
F.
G.
H.
I.
J.
K.
L.
M.
N.
PART 3:
Site Name, Location, and Brief Description.
Site History and Enforcement Activities
Community Participation
Scope and Role of Operable Unit or Response Action
Site Characteristics
Current and Potential Future Site and Resource Uses
Summary of Site Risks
Remedial ACtion Objectives
Description of Alternatives
Summary of Comparative Analysis of Alternatives
Principal Threat Waste
Selected Remedy
Statutory Determinations
Documentation-of Significant ,Changes
RESPONSIVENESS SUMMAKY
E-Mails
Page
iv
V
1
6
6
8
12
13
19
39
44
54
56
73
80
80
90
93
94
94
Letters
Phone Messages
Public Hearing Testimony
Technical Issues
APPENDIX A
95
108
110
11.5
A-1
ooo
lU
Figure 1:
Figure 2:
Figure 3:
Figure 4:
Figure 5:
Figure 6:
Figure 7:
Figure 8:
LIST OF FIGURES
Regional Location Map
Sulfate Concentrations
Model Prediction, Reduced Pumping, Layer 4, Year 2022
Model Prediction, Reduced Pumping, Layer 4, Year 2047
Model Prediction, Reduced Pumping Layer 4, Year 2147
Geologic Cross Section
Well Inventory Map
Land Use Map
Page
.7
29
30
31
32
-37
38
43
iv
LIST OF TABLES
Summary of O152 Enforcement Activities
Kennecott Operable Units
Kennecott South Zone Environmental Cleanups
Volume of Contaminated Ground Water
Concentrations of Chemicals of Concern
Water Suppliers and Sources of Water
Types of Water Uses
Concentrations of Chemicals of Concern
Health Effects of Elevated Inorganic Components in Drinking Water
Risk of Chemicals of Concern in Acid Plume
Comparison of Water Quality ku Wells with Jordan River Water Quality
Standards
Potential Concentrations of Contaminants in Jordan River if Acid Plume
is not Contained
Estimated Costs for Alternative 1
Estimated Costs for Alternative 2
Estimated Costs for Alternative 3
Estimated Costs for Alternative 4
Estimated Costs for Alternative 5
Estimated Costs for Alternative 6
Summary Table of Alternatives
Page
10
13
16
25
26
40
41
44
47
48
50
52
57
59
61
64
67
70
78
V
Project Cost Estimate, Capital Costs
Estimated Annual Proje~ Costs, Operations and Maintenance
Summary of Total Costs, Capital and Net Present Value
Final Cleanup Levels for the Selected Remedy
Appendix A, Federal and State ARARs
83
85
87
88
A-1
vi
A*
Co
RECORD OF DECISION
KENNECOTT SOUTH ZONE OPERABLE UNIT 2
SOUTHWEST JORDAN RIVER VALLEY GROUND WATER PLUMES
PART 1: DECLARATION
Site Name and Location
This Record of Decision covers Operable Unit 2 (Southwest Jordan River Valley Ground
Water Plumes) of the Kennecott South Zone Site, proposed for the NPL in 1994.
Operable Unit 2 is located in Salt Lake County, Utah, and encompasses the groundwater
beneath all or portions of the municipalities of West Jordan, South Jordan, Riverton,
Herriman, and portions of unincorporated Salt Lake County. The CERCLIS ID is
UTD000826404.
Statement of Basis and Purpose
This decision document presents the Selected Remedy for the Kennecott South Zone
Operable Unit 2 Site in Salt Lake County, Utah, which was chosen in accordance with the
Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), as
amended by the Superfund Amendments and Re, authorization Act (SARA), 42 U.S.C. §§
9601 et. seq, and, to the extent practicable, the National Contingency Plan (NCP), 40
C~F.R. Part 300. This decision isbased on the Administrative Record file for this site.
The State of Utah concurs with the Selected Remedy. Their concurrence is based upon
the belief that the remedy will benefit the puSlie within the affected area and begin to
protect public health and the environment.
Assessment of Site
The response action selected in this Record of Decision is necessary to protect the public
health or welfare or the environment fi’om actual or threatened releases of hazardous
substances and pollutants or contaminants into the environment.
Description of Selected Remedy
The selected remedy for Operable Unit 2 (Southwest Jordan River Valley Ground Water
Plumes) addresses the ground water contamination for this Kennecott South Zone Site.
The surface contamination which originally constituted the principal threat at the site has
already been addressed in other removal and remedial actions at OUI (Bingham Creek),
OU3 (Butterfield Creek), OU4 (Large Bingham Reservoir), OU5 (ARCO Tails), OU6
(Lark Tailings and Waste Rock), O157 (South Jordan Evaporation Ponds), OU10
(Copperton Soils), and OU17 (Basfian Area).
For purposes of clarifying agency authority over the cleanup operations of this action, the
agencies plan on using a joint CERCLA and State NRD approach. The cleanup strategy
presented within the text of this ROD is concerned primarily with the acid plume in Zone
A, under CERCLA authority. EPA maintains the fight to intervene in the cleanup of the
sulfate plume in Zone B, if it is not addressed sufficiently by the State NRD action. The
State of Utah will maintain authority of operations, in both Zones A and B, as they are
intended to fulfill the requirements of the NRD settlement. (Please refer to the footnote at
the bottom of page 28.)
The performance standards for the selected remedy include achieving the primary drinking
water standards in the aquifer of Zone A at the Kennecott property line (as of the date of
the signing of this document) for all hazardous substances (i.e. metals). Active
remediation (pump and treat) is required t0 ach/eve the health-based goal of 1500 ppm for
sulfate while monitored natural attenuation is used to achieve the State of Utah primary
drinking water standard for sulfate at 500 pprrL The water treated and delivered for
municipal use must achieve all drinking water standards of the State of Utah, as a
requirement of both the CERCLA action and the Natural Resource Damage (NRD)
settlement between the State of Utah and Kennecott Utah Copper Corporation. The
performance standard for treatment residuals asmeasured at or before the end of the
tailings pipe is demonstration that the railings/treatment residuals combination meets the
characteristics of non-hazardous waste.
The selected remedy involves treatment and containment ofcontaminated ground water
plumes. Theprincipal threats which caused the ground water contamination have been
addressed in previous actions or are contained under provisions of a Utah Ground Water
Protection Permit.
The selected remedy contains the following dements:
Continuation of source control measures as administered through the State of Utah
Ground Water Protection Program.
Prevent human exposure to unacceptably high concentrations of hazardous
¯ substances and/or pollutants or contaminants by limiting access to the
contaminated ground water. Institutional controls include purchases of land,
purchases of water fights, limiting drilling of new wells and increased pumping of
nearby old wells as approved (on request) and administered through the State of
Utah State Engineer (Division of Water Rights).
Prevent human exposure to unacceptably high concentrations of hazardous
substances and/or pollutants or contaminants through point-of-use management
which includes providing in-house treatment units to residents with impacted wells,
replacement of their water by hooking the properties up to municipal drinking
2
and/or secondary supplies, and/or modifying their, wells to reaeh uncontaminated
waters.
Contain the acid plume in Zone A by installation of barrier wells at the leading
edge of the contamination (1500 ppm sulfate or less), pump and treat the waters to
provide a hydraulic barrier to further plume movement while providing treated
water for municipal use. The treatment technology for the barrier well waters is
reverse osmosis.
Withdraw the heavily contaminated waters from the core of the acid plume in Zone
A find treat these contaminated waters using pretreatment with nanofiltration or
equivalent technology, followed by treatment with reverse osmosis to provide
drinking quality water for municipal use.
Monitor the plume to follow the progress of natural attenuation for the portions of
the Zone A plume which contain sulfate in excess of the state primary drinking
water standard for sulfate (500 ppm sulfate).
Disposal 0ftreatment concentrates in existing pipeline used to slurry tailings to a
railings impoundment prior to mine closure.
Development of a post-mine closure plan to handle treatment residuals for use
when the mine and mill are no longer operating.
E°Statutory Determinations
The selected remedy is protective ofhuman health and the environment, complies with
Federal and State requirements that are applicable or relevant and appropriate to the
remedial action, is cost-effective, and utilizes permanent solutions and alternative
treatment technologies to the maximum extent practicable.
This remedy also satisfies the statutory preference for treatment as a principal dement of
the remedy (i.e., reduces the toxicity, mobility, or volume of hazardous substances,
pollutants, or contaminants as a principal element through treatment).
Because this remedy will result in hazardous substances, pollutants, or contaminants
remaining on-site above levels that allow for u~ted use and unrestricted exposure, a
statutory review will be conducted within five years after initiation of remedial action to
ensure the remedy is, or will be, protective of human health and the environment.
ROD Data Certification Checklist
The following information is included in the Decision Summary section of this Record of
Decision. Additional information can be found in the Administrative Record file for this
site.
Chemicals of concern and their respective concentrations, pages 44-45.
Basel~e risk represented by the chemicals of concern, pages 48-49.
Cleanup levels established for ehemicals of concern and the basis for these levels,
pages 88-89.
How source materials constituting principal threats are addressed; page 19.
Current and reasonable anticipated future land use assumptions and current and
potential future beneficial uses of ground water used in the baseline risk
assessment and ROD, pages 40-42.
Potential land and ground water use that will be available at the site as a result of
the Selected Remedy, page 42.
Estimated capital, annual operation and maintenance (O&M), and total present
worth Costs, discount rate, and the number of years over which the remedy cost
estimates are projected, pages 83-87.
Key factor(s) that led to selecting the remedy (i.e., describe how the Selected
Remedy provides the best balance oftradeoffs with respect to the balancing and
modifying criteria, highlighting criteria key to the decision), pages 73-79.
4
G.Authorizing Signatures.
The following authorized oflioials at EPA Region VIII and the State of Utah approve the
selected remedy as described in this Record of Decision:
Max H. Dodson
Assistant Regional Administrator
Office of Ecosystems Protection and Remediation
U. S. Environmental Protection Agency, Region VIII
Dla~e/R Nielson, PI~ D
Executive Director
UtahDe)artment of Environmental Quality
Date
Date L
5
PART 2: DECISION SUMMARY
Site name, Location, and BriefDescription
The Kennecott South Zone Site, proposed for the NPL in 1994 (CERCLIS ID
UTD000826404), is located in southwestern Salt Lake County, Utah, and covers all or
portions of the municipalities of West Jordan, South Jordan, Riverton, Herriman, and
unincorporated S/dt Lake County. The lead agency for this CERCLA action is the U. S.
Environmental Protection Agency (EPA), supported by the State of Utah Department of
Environmental Quality (UDEQ). Cleanup funding will be provided by the respons~le
party. This action addresses ground water problems caused by over a centur), of mining
activities at the site.
The Kennecott South Zone site is located about 10 miles to the southwest of Salt Lake
City, Utah. lVfming began at the site in 1863 and has continued ever since. Waste
management practices of early miners included the dumping of wastes directly into
mountain creeks or storing them adjacent to streams. The streams carried the waste down
into Salt Lake Valley, which was then largely ranch and farm land. Now suburbs have
filled the valley near Salt Lake City. Miners also discovered that additional minerals could
be obtained by spraying their waste dumps with water. The wastes contained sulfides
which reacted with the water to form sulfuric acid. The acid leached minerals from the
waste rock. The miners then collected the metal beating acidic waters as they emerged at
the toe of the waste dumps. Later on, miners realized that the preemptive addition of
acidic water would actually increase mineral content of the leachate.
The collection system allowed substantial acid waters, laden with metals and sulfates, to
escape and contaminate the ground water. This has rendered a large area of the ground
water useless for drinking water, a serious m.atter in the semi-add west.
The Kennecott South Zonesite is composed of historic mining sites, of surface areas
contaminated by mining wastes which migrated from source areas downgradient to cities
and towns, and of subsurface areas contaminated by acid leachates from the mining
district.
The proposed action at the Kennecott South Zone site involves Operable Unit 02, the
ground wateroperable unit. Surface contamination was addressed by other actions. An
area map showing Operable Unit 02 study area and its relationship to nearby mining
activities is given in Figure 1 (Figure 1-1, from the Remedial Investigation Report).
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B.Site History and Enforcement Activities
Nfming activities began in the Oquirrh Motmtains of Utah in i863. Early miners recovered
mainly gold, silver, lead, and zinc but noticed extensive deposits of low grade copper ore
also. The leaching of copper into Bingham Creek was noted as early as 1885 by
government geologists. They observed that water which ran or percolated along the
copper ore body contained copper sulfate resulting from the oxidation of copper pyrites.
At that time, miners made no attempt to recover the very considerable quantity of copper
running down the canyon.
Later, in 19.03, two mining companies, Utah Copper and Boston Consolidated began
experimenting with minin~ milling and smelting techniques to exploit the extensive
porphyry copper deposits. They developed a mining technique known today as open pit
mining in Bingham Canyon and because space was limited for tailings disposal in the
canyon, the companies bu’dt mills about 13 miles away on the shores of the Great Salt
Lake. A smelter was built near the mills.
The open pit mining technique involved blasting the mountain side, later the pit, tO obtain
the ore, and then send the ore to the mills while dumping the waste rock in nearby gulches.
Waste rock also contained minerals, but in concentrations too low to recover
economically using milling techniques. It was not long before miners began to notice blue
water containing substantial concentrations of copper coming from the toe of the various
waste rock dumps in the canyon. Although there were smalloperations established at the
toe of each dump before this, Utah Copper, a predecessor to Kennecott Utah Copper,
began a full scale operation to collect the acidic metal beating waters into a central
recovery plant in about 1923. By 1929, Utah Copper Staff admitted that they had doubts
¯ that the company would ever be able to catch all the copper running to Bingham Creek
from their growing waste rock dumps.
Kennecott Utah Copper Corporation [hereafter referred to as ,Kennecott]") I upgraded
their leach water collection system in 1965 when they installed the unlined Large Bingham
Reservoir on a former tailings pond at the mouth of Bingham Canyon. Ditches conveyed
the leach wafers to the reservoir for storage prior to recovery of the copper in the’tr
precipitation plant located just upstream of the reservoir. After recovery of the copper,
the waters, still acidic, were recycled back to the top of the waste rock dumps. Water
balances calculated at the time suggested that water was escaping from the reservoir.
Kennecott estimated that the loss of water from the reservoir was 1 million gallons per
day. Kennecott used this reservoir from 1965 to 1991, a period of 26 years. During that
i The name "Kennecott" has been used by various entities, some associated with mining
activities in Bingham Canyon and some not associated with these activities. " Kennecott" as used
in this document refers toKermeeott Utah Copper Corporation and other entities using the name
"Kennecott" that were connected with historical activities described in this documer/t.
time, an estimated 9.5 - 16 billion gallons of highly contaminated waters characterized by
low pH, high metals, and sulfate, had escaped into the ground water. KennecoU began to
monitor the ground water downgradient of the reservoir starting soon after the reservoir
was constructed. In 1991, Kennecott retired the old reservoir, cleaned out thesludges and
tailings on the bottom, and reconstructed the reservoir. This new reservoir has three
basins, is triple-lined and is equipped with a leak detection system.
Kennecott also upgraded canals leading to the reservoir and built cut-off wails across
canyon drainages keyed into bedrock to prevent any acid leach waters from traveling
underneath the collection system in the alluvial material. Former leakage rates from this
source have not been estimated. In the fall of 2000, Kennecott ceased active leaching of
their waste rock dumps, although flow from this operation will continue for some time.
Even after flow from the active leaching operations has been flushed out, mineral-laden
acidic waters will still come from the waste rock dumps but this willbe the result of rain
or snow falling on the dumps (no excess waters or acids are pumped back to the dumps~to
increase flows or recoveries).
Several other mining activities caused or contn~buted to ground water contamination.
Along the eastern front of the Oquirrhs are several old mining adits and tunnels, some of
which continue to discharge waters. The Mascotte Tunnel was originally driven in 1901
to provide an ore haulage route and drainage outlet from several mines in the Bingham
Canyon. Waters infiltrating this tunnel contained so much copper that the mine owners
constructed precipitation launders inside the tunnel. This process was enhanced by adding
excess water to the dumps above the tunnel. Active leaching ceased about 1931. Before
Kennecott began to capture these waters, the waters were used for irrigation. The
Bingham Tunnel was originally driven in 1950 to provide an alternative ore haulage route
and drainage for the pit. The water was also used for irrigation purposes. The Bingham
Tunnel still has some water drainage currently, but the waters are now diverted into the
leach water collection system.
Excess waters from Bingham Creek, not known for its pristine waters, were discharged
into evaporation ponds built in the valley to the east beginning in the 1930s. These ponds
were initially not lined, had gravel bottoms, and the water was not treated. Although the
water certainly disappeared, evaporation was not the main mechanism of loss. During the
wet years of the 1980s, several of the ponds were lined with clay and the water was
neutralized with lime before discharge. The surface wastes in the footprint of the ponds
were removed or consolidated and capped in 1994. The ground water plume emanating
from this facility is being addressed as part Of the separate Natural Resources Damage
(NRD) settlement between Kennecott and the State of Utah.
Investigations regarding the ground water contamination began in 1983. A five year study
launched in response to the State of Utah Natural Resources Damage Claim started in
1986. A Focused Feasibility Study began in 1992 under CERCLA authority to quickly
9
eliminate alternatives that were not feasible and/or were not cost effective. The Remedial
Investigation/Feasibility Study (RI/FS) began in 1995 under provisions of a Memorandum
of Understanding (1995) between EPA, the State of Utah, and Kennecott. The NRD
settlement was also reached in 1995. The RI/FS document was submitted in 1998,
although additional experiments relating to remedial design (RD) are on-going and will be
completed during RD. Several treatment technologies were tested using pilot plants
beginning in 1996 through the present. A plan to satisfy the provisions of the Natural
Resources Damage (NtLD) settlement was presented to the State Trustee for Natural
Resources in December of 1999. The plan is currently undergoing fmal revisions.
Significant enforcement actions (involving OU 02) are listed in the following table:
SUMMARY OF OU2 ENFORCEMENT ACTIVITIES
1990
1991
1994
Utah Department of Health files a complaint
against Kennecott in Federal Court seeking
damages.under NRD provisions of CERCLA.
°,,
Settlement reached between Kennecott and
Utah Department of Environmental Quality. A
proposed consent decree was lodged ’with
Federal Court.
EPA opens site-wide remediation Consent
Decree negotiations.
EPA proposes the Kennecott South Zone for
the NPL.
Status
Trial put on hold while the
parties coUectedmore
information about the extent
of contamination. The study,
called the Five Year Study,
was not formally completed.
After substantial negative
comment during the public
comment period, the Federal
District Court rejected the
Consent Decree. Appeals to
both the Court of Appeals
and the Supreme Court were
unsuccessful in overturning
the rejection.
Negotiations fail in late 1993;
there are too many unknowns
for both parties~
The site is still proposed for
the NPL.
l0
Date Action Status
1995
t995
After substantial changes and inchsionofwater
purveyors in the negotiations, a new consent
decree for the NKD claims of the state trustee
was lodged in Federal Court.
\
EPA, Kennecott and UDEQ sign a
Memorandum of Understanding which required
Kennecott to perform an RI/FS at OU2 (along
with other cleanups) in exchange for EPA
taking no further action regarding final NPL
listing.
Upon agreement of the three
parties, the Consent Decree
(CD) was entered by the
Court. The CD established a
trust fund sufficient to finance
a remedial project to supply
treated water through the
replacement and/or
restoration of the lost
resource. Kennecott can
apply for monies from the
trust fund if specific criteria
are met. A plan for use of
these funds was submitted to
the state trustee in late1999.
The RI/FS for OU2 required
by the MOU was submitted
by Kennecott in March, 1998.
1
EPA has approached Kennecott Utah Copper Corporation, a wholly owned subsidiary of
Rio Tinto, as a potentially responsible party for OU2. Special Notice letters have not been
issued.
11
Co Community Participation
Community participation for this operable unit began in 1992 when a Technical Review
Committee was formed which included scientists and engineers from federal agencies,
state agencies, local county and municipal governments, water purveyors,
environmentalists, and citizen groups. The members were chosen to represent their
communities both to brief them on issues and to bring back concerns to the group. Over
’the course of the investigations, the committee met over 24 times to reviewwork plans,
evaluate progress reports, and discuss issues regarding the treatment alternatives. Future
water use needs and land use trends were also discussed during these meetings. A
Technical Assistance Grant (TAG) was awarded to a citizen group, Herriman Residents
for Responsible Reclamation (HRRR). They were also active participants in the Teelmical
Review Committee.
The Community Participation Plan for the site was outlined in 1991, but was augmented
with more detailed plans for each clean up action. For the ground water operable unit, a
mailing list of 2000 private and public well owners was developed. Fact sheets, briefings,
site tours, and open houses were scheduled periodically throughout the project. Both
print and electronic media covered most of the events. One screening exercise was
conducted in 1993, and the public were able to voice their concerns early in the study
process. This information was used during RI/FS seeping.
The KI/FS reports, a companion Natural Resource Damage proposal, and the CEKCLA
Proposed Plan were made available to the pubfic on August 1, 2000: These documents
are located at the City Recorder’s Office in West Jordan City Hall, the offices of Utah
Department of Environmental Quality in Salt Lake City, and at the Superfund Records
Center in the EPA Region VIII office in Denver. The notice of availability of these
documents was advertised in the Salt Lake Tribune and the Deseret News on July 31,
2000. A public comment period was held from August 1, 2000 to August 30, 2000. City
councils were briefed and a site tour for elected officials and’the media within the Salt
Lake Valley was held on July 26, 2000. The problem and proposed plan received
extensive media coverage in both local newspapers and on at least one TV station. An
open house was held at the offices of Utah Department of Environmental Quality in Salt
Lake City. This format gave citizens an opportunity to talk with project principals. The
public hearing was held on August 9, 2000, in the City Counc’tl Chambers of West Jordan
City Hall. EPA’s responses to the comments received during this period are included in
the Responsiveness Summary, which is a part of this Record of Decision. Concerns of the
public included potential impacts of the project on other water rights holders, water uses,
and costs to municipal and private water customers.
12
Vt Scope and role of operable unit or response action:
When proposed for listing on the NPL, the Kennecott properties were.divided into two
zones (Kennecotf South Zone and Kennecott North Zone) because the two areas were 10
miles apart. However, in reality, the two zones are technically managed as one site
because Kennecott continues to mine ore and process minerals miliz~g both zones and
they are functionally connected via several pipelines, roads, and rail lines. For example,
wastes produced by Kennecott’s Copperton Concentrator located in the South Zone are
slurried to a tailings pond in the North Zone. Waters generated in the North Zone are sent
by pipeline to the South Zone for use during the processing of the ore. For this reason,
activities in either site can affect operations at both sites. There are 22 Operable Units
within the Kennecott sites.
In general, because the overall site is so large, a step-wise site cleanup strategy was
implemented by EPA, the State of Utah, and Kennecott, asgenerally outlined in the site-
wide Memorandum of Understanding of 1995. First, CERCLA removal authorities were
used to cleanup surface wastes. These actions started in 1991 and are essentially complete
in 2000. Second, CERCLA remedial authority as well as the State of Utah NP, D authority
will be used to cleanup ground water. Finally, the State of Utah permitting authorities, in
particular, Ground Water Protection Program Permits, will be used to oversee routine
operations and maintenance of the remedies.
The descriptions Of operable units related to OU2 and the status of each are given in the
table below:
KENNECOTT OPERABLE UNITS (Related to OU2)
OUNo.
OU1
0132
Description and relationship to OU2
Surface contamination in Bingham Creek and
flood plain. A potential former source of
groundwater contamination to OU2.
)
Groundwater plumes in the South Zone
1. Zone A, the acid plume.
Status
Cleanups completed by three
removal actions, one fund
lead, two PRP enforcement
actions. Final ROD issued
1998/Two Consent Decrees
with the two PRPs were
entered in 1999.
RI/FS work¯ completed in
1998. This is the subject of
this Record of Decision.
13
OU No.
OU2
OU3
OU4
OU5
OU6
OU7
OU10
Description and relationship to OU2
Groundwater plumes in the South Zone
2. Zone B, thesulfate plume.
Surface contamination in Butterfield Creek and
flood plain. A potential source of groundwater
contamination to OU2.
The Large Bingham Reservoir. This reservoir
leaked about 1 MGD into the underlying
aquifer. The reservoir was the most Serious
source of groundwater contamination to OU2"
(Zone A).
ARCO Tails. Surface contamination produced
by non-Kennecott mines in Bingham Canyon.
Degree of contribution of groundwater
contamination unknown. The site is
immediately downgradient fi’om the Large "
Bingham Reservoir and is above some of the
highest concentrations in the groundwater.
Lark WasteRock and Tailings. Surface¯
contamination produced by mines and mills
near the former town &Lark, Utah. A known
source of groundwater contamination to OU2.
South Jordan Evaporation Ponds. Surface
contamination produced by disposal of mine
waters from Bingham Canyon. Theponds
were the second major source of groundwater
contamination to OU2 (Zone B).
Copperton Soils.
Status
State/Kennecott NRD
Consent Decree entered in
1995. Plan submitted to
trustee in Dee. 1999.
Approval pending.
Cleanups completed by three
removalaetions, two PRP
enforcement actions, one
mixed funding.. Final ROD to
be issued 2001.
Old reservoir retired and
cleaned under AOC. A new
lined reservoir went into
service in 1994. Final ROD
issued 1998. The site was
included in the OU1 Consent
Decree of 1999.
Cleanup completed under
terms ofa UAO about 1997.
Final ROD issued 1998.
Consent Decree entered for
O&M 1999.
Cleanups completed under an
AOC, 1994. Final ROD to be
issued 2001.
cleanups completed under an
AOC 1995. Final ROD to be
issued 2001.
Contamination not severe
enough to warrant action.
Final ROD issued 1998.
14
OUNo. "Description and relationship tO OU2 Status "
OUli Bingham Canyon. Surface and subsurface With minor exceptions, most
contamination. A suspected source of ground of these sites were buried or
water contamination.excavated by later mining
operations. No further action
needed. Final ROD issued
1998.
OU12 I Eastside Collection System. This systemwas The system was reconstructed
constructed to recover acid leachate fi-om mine in 1993-1996 under
dump leaching operations. A source of’provisions of a state . ,
groundwater contamination.groundwater permit.
OU16 Bingham Canyon Underflow. This is a plume ¯This flow was intercepted
of acidic waters flowing in the alluvium through construction of a
underneath Bingham Creek in Bingham eutoffwall keyed into
Canyon. A source of groundwater bedrock under the provisions
contamination. Also, acidic waters have been of a state groundwater
found in bedrock underlying Dry Fork, a permit. The Dry Fork
Bingharn Canyon tributary. The significance as bedrock aquifer is under
a potential source is unknown.investigation by the state
ground water program.
OU17 Bastian area. Surface contamination resulting Surface contamination was
from the use of contaminated irrigation water.not severe enough to warrant
The site overlies the groundwater plume further action except in an
emanating from the Large Bingham Reservoir.historic ditch. Cleanups of
the ditch were performed by
enforcement actions at OU5
and OU6. Final ROD issued
in 1998. ."
OU15 Magna Tailings Pond. Tailings generated by Surface discharges from the
(North two mills are stored in this facility at the North pond are subject to a UPDES
Zone)End. The pond is likely to be used as ma permit. Subsurface
integral part of the OU2 action while mining discharges are covered under
operations continue.a State groundwater permit.
OU22 Great Salt Lake. Surface water body receiving There are no water quality
(North [ discharges from Magna Tailings Pond and standards for the Great Salt
Zone)other Kennecott waters.Lake at present. Relevant
ecological studies were
performed as a part of the
North Zone studies.
15
. °
OU No.Description and relationship to OU2 Status
=" . ’
OU20 Pine Canyon. Kennecott lands on the west Kennecott lands in Pine
slope of the Oqu’wrhs are a part of the Canyon have been given a No
Kennecott South Zone. However, drainage is Further Action Status. As a
to the other side of the mountains and this area part of the newly proposed
is not a source of groundwater contamination areas of Phae Canyon,
at OU2. Non-Kennecott owned land in this ¯ negotiations with the other
area was divested from the Kennecott South party for a R3/FS are
Zone to another proposed NPL site,underway.
International Smelter.
The sequence of cleanups are/were as follows:
KENNECOTT SOUTH ZONE ENVIRONMENTAL CLEANUPS
Date
(calendar)
1991
1992-1994
1992-1994
1993-1994
1993-1994
Action
Bingham Creek¯
residential soils
Buttertield Mine
¯ Waste Rock
Large Bhngham
Reservoir
Bingham Creek
sediments
Lark Waste
Rock and
Tailings
Authority
Time Critical
Removal
Time Critical
Removal
Time Critical
Removal
Time Critical
Removal
Problem
Flood plain soils were
contaminated by lead from
upstream mining activity. The land
was developed for residential use.
,%
High concentrations of lead in
waste rock were left in and
adjacent to Butterfield Creek.
Materials were eroding into the
creek.
Acid leachate leaked from
reservoir into ground water.
High concentrations of lead in
tailings deposited in former creek
channel were continuing to erode
downstream.
concentrations of lead and
arsenic in tailingswere present. 3m
addition, high concentrations of
sulfides in waste rock produced
acids leaching into the ground
water.
16
Date Action Authority Problem
(calendar)
1993-t997 ARCO Tailings Time Critical High concentrations of lead,
Removal arsenic and sulfides in tallings
deposited in and adjacent to
Bingham Creek eroded
downstream and potentially
leached to ground water.
1993-1996 East§ide State Ground The collection system is designed
Collection Water Permit to contain acid leachates coming
System,fi’om Bingham 1Wine waste rock¯
Bingham Tunnel,sulfides. It also collects mine
Mascotte Tunnel drainage from adits.
1994-1995 South Jordan Time Critical Waste water settling pond sludges
Evaporation Removal were a known source of ground
Ponds water contamination via
infiltration.
1994 Off-site historic PA/SI-like Surface drainages from the mining
facilities investigation district were screened for
contamination.
1994-2000 On-site historic IPMSLIike Individual waste piles were
facilities investigation screened and checked for mobility
into ground or surface waters..
|,,
I995-1997 Bingham Creek Time Critical Final clean up of residential soils
residential soils Removal contaminated by railings in the
flood plain of BinghamCreek.
i997-2000 Herrirnau Time Critical Residential soils were
residential soils Removal contaminated through use of
L.contaminated mine waters for
irrigation.
1~97-1998 Buaerfield Time Critical Tailings left by historic ore mill left
Canyon Removal in Butterfield Creek were eroding
downstream.
1998 Bingham Canyon State Ground Contaminated flow in alluvial
Underflow Water Permit gravels of Bingham Creek
contributed to ground water
1 contamination in the valley.
17
Date "
(calendar)
1998
2000
2001
2001-2002
2005
Action
Bingham Creek
surface waste
South Zone
I Ground Water
Butterfield-Lark
surface waste
Precipitation
Plant
Site Wide
Authority
Remedial
Remedial
Remedial
Remedial
Remedial
Problem
No Action ROD.
1
The focus 9fthis ROD, RD/RA
begins 2001.
, ,., ,.
Institutional Controls only ROD is
anticipated in 2001.
Decommission, demolish, and
clean soils surrounding former
processing plant for leach water.
The plant was closed in 2000.
q. ¯
Construction Complete.
18
E.Site characteristics
1.Conceptual Site Model and Description:’
Sources [
]1
Human ingestion via wells [ [
i
Ecological receptors in the Jordan River
via seeps and infiltration.
Sources: The major source of the contaminated ground water in Zone A was
leakage from the Large Bingham Reservoir. Other sources included acid leachate
leaking or escaping capture from the Eastside Collection System (includes
Buttertield Creek and Bingham Creek underflow), and historic tunnels at Lark.
The sources of contaminated ground water in Zone B were leakage from the South
Jordan Ev.aporation Ponds and several non-mining sources. The mining-related
sources have all been addressed by previous response actions.
Contaminated Ground water:For administrative purposes the ground water
plumes have been divided into two zones. The acid plume (sometimes referred to
as the CERCLA plume) in Zone A contains low pH waters and high metals with
sulfates exceeding the CERCLA recommended risk based action level of 1500
ppm, The sulfate plume (sometimes referred to as the NRD plume) in Zone B
contains waters exceeding the Secondary Drinking Water Standard for sulfate of
250 pprrL For the purposes of this ROD, the plumes will be described as Zone A
for the acid plume or Zone B for the sulfate plume. Although the waters in Zone
B do not rise to the level of a health risk, they are not useable for public drinking
water supplies without blending or treatment. The Zone A acid plume originates
largely from the Large Bingham Reservoir. The sulfate plume originates flora the
South Jordan Evaporation Ponds in Zone B and the migration of sulfate-laden
ground water from Zone A. (See Partl, Declaration, for the division of authorities
used in the combined CERCLA-NRD action.)
Human ingestion: Ingestion of contaminated well water is the major pathway of
potential human exposure for people in the affected area. There are some other
19
°
3.
minor concerns which include using the water for irrigation and stock watering
purposes. The exposure points are scattered throughout the aquifer at private and
municipal wells.
Ecological receptors: The ground water in this area flows from the mountain
recharge areas to the Jordan River which is the point of.discharge and exposure
pointto aquatic organisms living in the river. The Jordan River near the affected
area is classified as a cold-water fishery. The discharge oftreatmentbrines is a
potential problem for the Great Salt Lake ecology.
Overview of the site:
Size of the site: The contaminated ground water underlies a 72 square mile area.
The core of the acid plume is about 2 square miles in size.
Geographical and topographical information: The site is located in the Southwest
portion of the Jordan River Valley. On the western edge of the site is the Oquirrh
Mountain Range which has been an important mining area in the State of Utah
since 1863. Several creeks begin in these mountains and historically flowed
toward the east and the Jordan River. These creeks include Bingharn Creek,
Midas Creek, and Butterfidd Creek. Today, because virtually all the water coming
from the mountains is captured for use as industrial or irrigation waters, the creeks
do not flow except during rain events. Each of these creeks has an associated
flood plain, but the size of the current flood plain is much smaller today than
historically due to the impoundment of these waters. Buffed channels of these
creeks often serve as preferential flow pathways for subsurface waters.
Because of the availability of water during historic times, several farming
communities were founded along the creeks. With the growth of urban
development in Salt Lake Valley, most of these communities are now suburban in
character and are part of the Salt Lake City Metropolitan area. The Cities of West
Jordan, South Jordan, and Riverton, and the Town of Herriman overlay the
contaminated ground water.
Except in and near the mountains, the valley floor is relatively flat, gently sloping
toward the Jordan River. There are some wetlands adjacent to the Jordan River at
the eastern boundary of the site. The wetlands are fed by seeps originating l~om
the shallow aquifer. In addition, several of the cities along the Jordan River are
considering wetland restoration projects in this area.
Surface and subsurface features:
Proceeding from west to east, surface features in the Oquirrh Mountains and
20
4.
foothills include mining operations of the Kennecott Utah Copper Corporationand
remnants from historic mining activitieS. The facilities which were implicated in
ground water contamination are described later. Adjacent to the mountains is a
band of agricultural lands either owned by Kennecott and leased to farmers or
privately held. Over the eastern edge of the site are three clries, In addition,
transeeting the site from north to south are several irrigation canals which
transport Utah Lake water and Jordan River water inland for use by farmers and
residents for irrigation of lawns, crops, and gardens. Subsurface features are
largely associated with infrastructure of the cities, such as sewers, waterlines, gas
station tanks, etc. The overlying municipalities have associated residential and
commercial zones, some of which have private wells. Some of the municipalities
have municipal or private water.company well fields for the production of water.
Areas of archaeological or historical importance: There are numerous areas of
historical significance including the mining district itself and early structures built
by the Pioneers who settled here beginning in 1847. Areas of historical
significance would not be affected by the proposed action.
Sampling strategy:
Samples of ground water were collected ~a order to determine the lateral and
vertical extent of the contamination, monitor plume movement over time, provide
data needed to cah’brate the ground water model, characterize aquifer materials,
determine if private well owners need irrmlediate relief~ and provide early warnings
should municipal water supplies be threatened. Samples of ground water were
also used in studies to assess potential impacts to various water uses such as
irrigation and industrial waters. Ground water was also used in pilot testing for
dements of the alternative remedies and the characterization of potential waste
streams. Routine monitoring of somewells is required as a part of the state
ground water permit to determine if leakage from operating facilities is occurring.
Many of the wells were used in a multivariate statistical approach for the
determination of background concentrations. Some were used for isotopic tracing
and age dating purposes.
All private and municipal wells were monitored at least once. Wells close to the
sources were monitored quarterly and others less frequently. The historic database
on ground water quality dates back to the early 1960s, but most of the wells were
installed in the late 1980’s. Several of the recently installed wells in the heart of the
plume have completions at multiple depths so that water from different layers in
the aquifer can be sampled from one well. (See KI/FS for further details.)
21
5.Description of known or suspected sources of contamination:
The major source of contamination to the ground water in Zone A was the Large
Bingham Reservoir, formerly used to collect leach waters and runoff from the
Bingham Canyon open pit mine. It also contained water associated with waste
rock dump leachate, and flows from Bingham Creek.
The former Large t~ingham Reservoir was constructed in 1965, and retired from
service in 1991. It is suspected that during the entire history of the operation of
this reservoir, leakage rates to the underlying aquifer averaged about 1180 gpm
(approximately 1 million gallons per day). The waters in the reservoir were
characterized by low pI-/, high metals, and very high sulfate, all characteristic of
acid rock drainage. This area was designated OU4 of the Kennecott South Zone
site. The sludges, tailings, and underlying soils were removed in 1992-1993 and a
new lined reservoir with three basins was constructed in 1994-I995. The cleanup
was performed under CERCLA removal authorities and provisions of a state
ground water permit.
Another source of ground water contamination in Zone A was Bingham Canyon
alluvial flow, sometimes referred to as Bingham Creek underflow. In Bingham
Canyon, the flow of Bingham Creek is only partially at the surface. A substantial
flow travels in the alluvium at the interface between the bedrock and the channel
alluvium. These waters are also characterized by low pH, high metals, and high
sulfate. Recent data suggests that this flow discharged into the principal aquifer at
a rate of at least 300 gpm. Kennecott installed some wells to intercept this flowin
1989 (not entirely successfial), and in 1996 built a cutoffwall at the mouth of the
canyon keyed into bedrock to capture the total flow. The degree to which flow in
the bedrock goes underneath the cutoff wall is unknown. This work was
performed under provisions of a state ground water permit. It is OU 16 of the
Kennecott South Zone.
Another source of groundwater contamination in Zone A was the Cemetery Pond,
located next to the Copperton Cemetery. It was built in 1984 and used until 1987.
It served as a lime treatment basin for treatment of acid waters from the Bingham
Canyon Mine and North Ore Shoot. It had a gravel bottom and leaked at an
estimated rate of 2000 gpra. The water was generally alkaline, but had elevated
sulfates and TDS. The bottom sediments contained elevated arsenic. This pond
was retired from service in 1992 and the sediments were cleaned out. The area
was included in the Final ROD for Bingham Creek in 1998.
Another source of ground water contamination in Zone A includes the waste rock
dumps and Eastside Leachate CollectionSystem. Early miners noticed that acidic
copper-laden waters were produced when rain water came in contact with sulfides
22
incorporated within the waste rock dumps. The sulfides were oxidized to form
sulfuric acid and the acid then leached metals out of the waste rock. (Note: Waste
rock does have some metal content but not enough to economically process.)
Miners began to collect the acidic metal laden waters and process them to recover
themetals. Kennecott enhanced this process by actively spraying the tops of the
dumps with recycled water starting in 1942. A system of canals were built to
collect the water at the toe of the dumps as the metal rich water emerged. Initial
activity was centered largely in Bingham Canyon. Excess.waters were sent to the
South Jordan Evaporation Ponds. The collection systemwas expanded in 1965 so
that leaching operations could be extended to the Eastside Dumps. The system
was upgraded in around 1982 using ponds and concrete ditches. Beginning in
1991, the collection system was again upgraded to install cutot~walls at gulches
keyed into bedrock in order to capture any undertlow through the alluvium. The
volume of acid waters escaping or eluding the capture system have not been
estimated. Preliminary data suggest that in certain areas (Dry Fork and Bingham
Canyon) acid leachate has penetrated into the bedrock aquifer. This potential
source of contamination is currently under investigation as part of the Utah
Ground Water Protection Program.
A known source of contamination in Zone Awas acidic discharges from historic
mine tunnels located along the east side of the Oquirrh Mountains. An area of
poor quality groundwater is located downgradient of the portals of two tunnels in
the old Town of Lark. The Maseotte Tmmel was originally constructed in 1902-3
to access the ore.body in the Oquirrh Mountains. It was also used as an outfall for
waters infiltrating into the mines. Water was pumped from the various shafts into
the tunnel. At onetime, the waters .contained enough metals that the miners set up
metals recovery launders within the tunnel itsel£. The water was discharged into
the area of the Lark Tailings dump until 1942. At that time a pond was
constructed (Mascotte Pond) and the water was used for irrigation. During active
pumping of the shafts serviced by the tumlel, flow rates were 1000 - 3000 gpm.
After 1952, discharges from Mascotte Tunnel were intercepted by the new
Bingham Tunnel nearby. Bingham Tunnel water, when it was not used for
irrigation in Herriman, was discharged to Midas Creek until 1988. The current
flow is 600 - 1000 gpm and is now routed into the Eastside Loaehate Collection
System described earlier.
A potential source of ground water contamination in Zone A was the Small
Bingham Reservoir adjacent to the Large Bingham Reservoir, described earlier. It
was built in 1965, was retired from service in 1988, and was reconstructed in
1990 with HDPE linings. It held waters similar in composition as the Large
Bingham Reservoir. Since it had only 4% of the capacity of the Large Bingham
Reservoir its leakage rate was probably small in comparison. The reservoir was
addressed in 1990 and was included in the 1998 ROD for Bingham Creek
23 :.
Another potential source of ground water contamination for Zone A located in the
Lark area was the Lark Tailings and Waste Rock site. This area was used as a
disposal site for tailings and wastes of various mining operations in the area. The
waste rock had the potential to generate acid waters. There has been no estimate
of the flow rate. In 1993, the railings with high metals were relocated to the
Bluewater Repository and the waste rockwas relocated to Kennecott’s main
waste rock dumps (behind the Eastside Collection System). There is one seep in
the Lark Tailings area which had moderately contaminated water. The seep is
used for experimentation using artificial wetlands for treatment of high sulfate
waters. The Lark area is OU 06 of the Kennecott South Zone. Cleanup was
performed by Kennecott using CERCLA removal authorities. A F’mal ROD for
this site has not been issued.
Another potential source of contaminated water in the vicinity of Bingham Creek
area was the ARCO Tailings (also called Copperton Tailings and Anaconda
Tailings). This seres of railings impoundments were e0nstructed around 1910 to
capture tailings from mining and milling operations of the Utah Apex operations
located in Bingham Canyon. Tailwaters were used by local farmers for irrigation
purposes. The impoundments were located immediately downgradient of
Kennecott’s Large Bingham Reservoir. The railings did have the potential to
generate acid waters, but it is unknown how much acid waters made it to the
underlying aquifer. This area was capped by ARCO under provisions of a removal
Unilateral Order in 1993-1997. The Final ROD wasissuedin 1998. The area is
OU 05 of the Kennecott South Zone.
The major source of ground water contamination in Zone B was the South Jordan
Evaporation Ponds. These ponds were used intermittently from 1936 to 1986 to
dispose of excess water from Bingham Canyon. The waters were acidic and high
in sulfate. The original ponds were not lined and had sand and gravel bottoms.
During the later period of operations, some of the ponds were lined and waters
were treated with lime before disposal. Infiltration rates varied depending on the
amount of water in the ponds. Estimates of 150 gpm to 1110 gpm have been
proposed. The ponds were retired from service in 1986. The ditches leading to
the ponds were cleaned as a part of the Bingham Creek removal action in 1992 and
the sludges remaining in the ponds Were addressed aspart of the South Jordan
Evaporation Pond Removal Action during the 1994-1997 time frame. This area is
OU 07 of the Kennecott South Zone.
Because the mining activities in the area have been ongoing since 1863 and
continue today, the sources of ground water contamination from these activities
Were numerous. An intensive effort to contain or remove these sources was the
first order of business at the Kennecott South Zone site. Currently, with the
potential exception of Dry Fork bedrockcontamination, all of the above known
24
6.
and potential sources associated with mining activities have been contained or
removed. There are other non-mining related sources that impact ground water.
Some of these are natural such as natural leaching of mineralized areas in the
mountains and geothermal activity. Others are man-made such as irrigation water,
canals and runofffi’om urban areas. For the purposes of this aetiort, the non-
mining sources are considered to be part of the "background’.
Types of contamination and the affected media:
Types and characteristic of Chemicals of Concern: Because the ground water
was contaminated through the release of acidic metal-laden waters emanating from
mining activities, the chemicals of eoneem are largely inorganic chemicals,
particularly metals and sulfates. The metals are mobile and toxic; some are
carcinogenic, and others non-carcinogenic. Mobility of the metals and sulfates is
enhanced in the presence of low pH waters near the sources. For operational
reasons the ground water has been divided into two plume areas, the acid plume
(the subject of this Record of Decision) and the sulfate plume (being addressed in a
separate Natural Resources Damages settlement). See also Part 1, Declaration, for
a discussion of the authorities and their role in the combined response.
Quantity~volume of waste: The Remedial Investigation estimated the volume of
contamination using different criteria. A summary table follows:
VOLUME OF CONTAMINATED GROUND WATER (ZoneA)
Contamination range Volume (aore-fee0
Sulfate concentrations > 1500 mg/l 171,000
B ingham Reservoir Area
Remaining areas ,
Sulfate concentrations> 20,000 mg/l
168,000
3,700
19,000
pH < 4.5 54,000
Concentrations of Chemicals of Concern: The chemicals of concern are different
for the two plumes. For the acid plume in Zone A, an e .xample of the
concentrations of the chemicals of concern in the ground waters close to the major
source in comparison with primary and secondary drinking water standards are
given in the following table (information from the RI/FS):
25
CONCENTRATIONS OF CHEMICALS OF CONCERN
(Downgradient of the Large Bingham Reservoir, all data)
Chemicals of concern Drinking water Max. concentration in Ratio
standard (primary or add plume (acid plumdstandard)
secondary) mg/l (downgradient of
¯ Large Bingham Res.)
=.J,
Arserllc 0.05 4.1 82
, .
Barium ~0.9 0.45 "
.. ,. ,
Cadmium 0.005 9.34 1868
Chromium 0.1 0.99 9.9
Copper "1.3 (action level)192 147
, =,
Fluoride . .16.2 4.05
Lead 0.015 (action level)0.85 56.6
Nitrate 10 .5. ¯0.45
Selenium 0.05 0.9 18
Nickel oLh)850 85OO
Aluminum 0.05- 0.2(secondary)4690 23450 - 93800
Chloride 250(secondary)539 2.1¯
Copper 1.0 (secondary)192 192
Fluoride 2.0 (secondary)16.2 8.1
Iron 0.3 (secondary)1222 4073
Manganese 0.05 (secondary)alOO 22000¯
pH ¯ ¯6.5 - 8.5 (pH units)2.6 (minimum pH)7943
Silver o.lo(secon&ary)0.24 2.4
Sulfate 250 (secondary)59,000 236
¯500 (secondary)77,574 155
Zinc 5 (secondary)544 109
26
7.
RCRA hazardous wastes: EPA is not making any determination on the Bevill
Exempt status for the ground water or treatment residuals at this time. (See
footnote at end of State ARARs discussion in Appendix A,
Description of the location of contamination and known or potential routes of
migration.
Lateral and vertical extent of contamination: The lateral extent of contamination
along with the known sources is shown on Figure 2 (Figure 4.4 of the Remedial
Investigation Report). As mentioned previously, there are two main plumes of
ground water contamination. The western plume, sometimes also known as the
acid plume or Zone A, is where the highest concentrations of contaminants are
found and is the subject of this Record of Decision. The ~ea exceeding one or
more primary drinking water standards measures about 5 miles by 5 miles. Within
the acid plume, there is a core area immediately downgradient of the Large
Bingham Reservoir, and minor fingers of contamination originating near the toe of
the waste rock dumps in various gulches including Bluewater I Gulch, Bluewater
II Guteh, Bluewater Gulch, Midas Gulch, Keystone Gulch (near the Bingham
Tunnel portal), North Copper Gulch, Copper Gulch, Yosemite Gulch, and two
gulches in Butterfield Canyon.
The depth to ground water ranges from 50 to 400 feet in the most heavily
contaminated core area near the Bingham Reservoir. The contamination in the
core extends to the bottom of the aquifer. The contamination in Zone A persists in
the top 100 - 600 feet of the principal aquifer on average. In the Lark area (the
finger of contamination starting near the Bingham Tunnel) the contamination is in
the top 50 to 150 feet of the principal aquifer.
Current and future locations: The location of the contamination relative to the
sources is shown on Figure 2 (Figure 4-4, reprinted from the Remedial
Investigation Report). This figure demonstrates sulfate concentrations. In
general, the low pH and high metal concentrations are located in the areas
designated by reds and orange on this figure. This portion is the core of Zone A.
Most of this plume originated from leakage.from the Large Bingham Reservoir.
/’&nor sources were leaks from the dumps (shown as fingers of contamination
coming down the western gulches). The plume in Zone A is the. subject of both
this lZecord of Decision and the Natural Resources Damages action,
In Zone B, the plume to the east is characterized by lower sulfate concentrations
with only a few hot spots of metals and low pH. This plume is known in various
documents as the sulfate plume, the NRD plume and Zone B. The major source
27
of sulfate Contamination in this area is the South Jordan Evaporation Ponds. It is
this area which is being addressed primarily using the Natural Resources Damage
Settlement.2
Both creese plumes were modeled in the RI/FS and the NRD Settlement
proposal to predict the migration of the plumes under different scenarios. An
example of one such scenario is given in Figures 3, 4, and 5 (Figures 5-9, 5-10 and
5-11 from the Remedial Investigation Report). These figures give the migration
predictions assuming no action and illustrates the movement of sulfate in 25 years,
50 years, and i50 years. In general, the plumes continue to move to the east,
away from the mountains toward the JordanRi;eer.
The model results point out three areas of concern tothe agencies. (1) AlterS0
years, the acid plume has reached the West Jordan municipal well field, the major
source of water for the city. (2) After 150 years, high concentrations of sttlfate
begin to approach the flood plain of the Jordan River presenting a threat to the
aquatic ecology of the river. (3) The highest concentrations of contaminants in the
plume will move off existing Kennecott property after 50 years.
~EPA reserves the fight to address contamination in Zone B if the NRD settlement is not
carried out in a manner acceptable to EPA or if new irtformation indicates that action by EPA is
warranted. Likewise, the state of Utah reserves the tight to use the NRD settlement provisions
should CERCLA RD/RA activities in Zone A be insufficient.
28
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32
Current and potential future surface and subsurface routes of human or
environmental exposure: As illustrated previously, modeling of the ground water
plumes suggest that the contamination will continue to migrate eastward toward
the Jordan River if nothing is done to contain or treat the plumes. The acid plume
may also migrate northward toward the West Iordan City municipal well field
depending on pumping rates by West Jordan. This could create a potential health
threat to the West Jordan City residents or cause abandonment of the well field.
Though Riverton City has a municipal well field as well, the main source of impact
to this system would be from the sulfate plume in ZoneB, the focus of the Utah
NRD action.
A well inventory was conducted during the RI/FS. The inventory located 1688
wells. Of these wells 523 were monitoring wells, 559 were in use, and 606 were
not in use, damaged or missing. Of the 559 wellsin use, 347 were used for
culinary purposes (either solely or in conjunction with other uses), and 212 were
used for other purposes such as stock watering, irrigation, commercial. Although
most of these well owners now have access to municipal water supplies, many
continue to use their wells for lawns and agricultural uses. The well inventory
represents information for both Zones A and B. Future exposure is possible if the
plumes are not contained.
Some preliminary ecological risk calculations were performed to assess ecological
risk. The two places where the plumes could discharge to surface water bodies are
the Jordan River and the Great Salt Lake. In both.cases, the current sulfate inputs
are minor in comparison to the sulfate already present in these water bodies. Note
that this describes the current condition, not the future threat which modeling
suggests might occur in 150 years (see later discussion). At that time, sulfate
loading from ground water could have a significant impact on the river.
Likelihood for migration for Chemicals of Concern: The agencies are certain
that the contaminants of interest will continue to move eastward if nothing is done
to contain or treat the plume in Zone A. The leading edge of the acid plume has
already moved 5 miles from its original source in the last 35 years. Although the
pH will be neutralized and the metals removed into the solid phases of the aquifer,
sulfate is totally soluble in water up to about 2000 ppm. As the water moves
around 500 feet/year, the sulfate will move with it. The movement of metals is
much slower beeause of the nentralization-precipitation chemical reactions with
the alluvium materials.
Human and ecological populations that could be affected: Although current
exposures are limited to the public with private drinking waterwells, the affected
area is located in a semi,add climate where water resource availability is a serious
issue.to all residents in the area. In addition to the private well owners, there are
33
8.
two municipal well fields just outside the area of the contamination. There is valid
concern that depending on the pumping scenarios, contaminated water could be
drawn in the direction of the municipal fields limiting their future Use as a water
supply. Most of the other residents in this area are served by public water
suppliers which import the water fi’om surface reservoirs in the mountains. The
ground water underlying these cities is a valuable resource which has not yet been
utilized by the municipal water purveyors due to the expense of dealing with the
contamination. Thus the entire population of thisarea is affected either directly by
ingestion of the water or indirectly by the extra cost of providing water i~om
outside the area. The population for both zones was estimated tobe 117,059 in
1997 and is projected to grow to 286,905 by 2020. Use of the ground water
resources of the affected area is desired by all the communities in the area.
Ecological receptors of untreated waters from the plumes are limited to the aquatic
species in the Jordan River. This is not a major concern currently because the
water quality of the Jordan River as it leaves its headwaters in Utah Lake is not
pristine and already contains substantial quantifies of sulfate. However, if nothing
is done to contain the plumes, the plumes will inevitably reach the Jordan River
and potentially affect all aquatic species living in the river and in the adjacent
wetlands.
Description of aquifer and ground water movement:
Aquifers affected or threatened by site contaraination, types of geologic materials,
approximate depths, whether aquifer is confined or unconfined and direction of
flow: There are three aquifers that are affected or potentially affected by the
mining related contamination for the two zones. The following is a description of
these aquifers starting with the bottom.
The bedrock aquifer underlies the entire valley at varying depths. The bedrock is
close to the surface in the Oquirrh Mountains plunging to a depth of about 2000
feet below ground surface in the middle of the valley. The bedrock is composed of
Paleozoic bedrock with a layer of Tertia/y volcanic rock above it. Both provide
recharge water to the Principal Aquifer. Hydraulic conductivity is low relative to
the principal aquifer, but is highly variable depending on the presence or absence of
fractures. The Eastside waste rock dumps are located on the Tertiary volcanic
rock. When the water percolating through the dumps encounters the bedrock, it
flows at the interface and emerges at the toe of the dumps. The degree to which
the acid-laden waters enters the Bedrock Aquifer is unknown. The degree to
which the waters are then discharged to the Principal Aquifer and where is also
unknown. The USGS and Kennecott are beginning to develop a model which may
provide insight on these issues. Hydraulic conductivities are 0.03 - 0.8 feet/day.
The direction of flow is variable depending on the direction of the fractures.
34
Abouta mile east of the eastern front of the Oquirrh Mountains, the bedrock is
overlain by the Jordan Valley Narrows Unit originating duringthe Oligocene-
Miocene period. It is described as interbedded clays and tuff and is considered by
most experts to be an aqultar& Its conductivity is estimated at 0.1 - 0.3 feet/day.
This is the bottom of the Principal Aquifer. The Bedrock Aquifer discharges to the
Principal Aquifer.
The Principal Aquifer overlies the bedrock layers near the mountains and the
Jordan Valley Narrows Unit farther out in the valley. It consists primarily of Pile-
Pleistocene alluvial fan deposits of quartzitic and volcanic gravel. In the central
part of the basin, the aquifer is relatively thick (up to 1000 feet) and is composed
of quartzific gravels. The upper 200-300 feet of the aquifer is particularly
productive with hydraulic conducti,~ities of 3 - 83 feet/day at the western part and
over 100 feet/day eastofthe Evaporation Pond site in Zone B. At the southern
part of the site near the mountains, the Principal Aquifer is mostly volcanic gravel
interbedded with clay and silt. The hydraulic conductivities in this area range I -
12 feet/day. The Bingham Reservoir and the Lark tunnelportals are both located
in the recharge zone 0fthe Principal Aquifer at the edge of the mountains in Zone
A. The relatively high hydraulic eonductivities allowed the contamination to
spread quickly. The flow of the Principal Aquifer is generally eastward with minor
directional changes in the presence of buried eharmels. The flow bends toward the
northeast near the Jordan River boundary (toward the direction of the Great Salt
Lake). The Principal Aquifer is considered to be unconfined in the area near the
mountains (Zone A), but is thought to be confined between the Evaporation Ponds
and the Jordan River (Zone B). The confining layer has not been thoroughly
investigated and may not be continuous. The Principal Aquifer eventually
discharges to the Jordan River and the Great Salt Lake.
The Shallow Unconfined Aquifer is found east of the Evaporation Ponds (Zone B)
and consists of quartzitic gravel intermixed with silt and clay. They are Bonneville
and Prove lacustrine deposits (Late Pleistocene and Holoeene). The conductivity
is low at about I ft/day. The flow direction is toward the east. The South Jordan
Evaporation Ponds contaminated both the Shallow Unconfined Aquifer and the
Principal Aqffffer in Zone B. The Shallow Unconfined Aquifer is also affected by
several unlined irrigation canals which traverse the area. The shallow aquifer
discharges to springs and seeps along the Jordan River.
Surface and subsnrface features: Features at the site which affect the quality of
the ground water ineludethe mining-related sources and several non-mining
related sources. ~vftning related sources include the former Small and Large
Bingham Reservoirs (now reconstructed with triple linings and leak detection), the
former Eastside Leachate Collection System (now reconstructed with cutoff walls
keyed into bedrock and with above ground HDPE pipes), theBingham Tunnel
35
portal (the tunnel discharge now goes into the reconstructed Eastside Collection
System), the Lark Tailings and Waste Rock (now remediated), all in Zone A, and
the South Jordan Evaporation Ponds (retired from service, remediated, and
partially redeveloper as residential property) in Zone B. The major non-mining
related sources are a series of unlined irrigation canals which are in use during the
growing season with waters mainly from Prove River and:Utah Lake. Because
others have wells in the area, agencies are aware that any increased pumping could
draw the plume in that direction, reduce water levels, or both.
Stratigraphy: An example of the stratigraphy with location of the contaminated
plume is shown in Figure 6 (Figure 4-8, from the Remedial Investigation Report).
The monitoring well map is shown in Figure 7 (Figure3-5a, also from the
Remedial Investigation Report).
Ground water models: Hydrologic, geochemical and contaminant transport models
were used to predict flow rates and contaminant movement. The flowmodel uses
a three-dimensional, finite difference, numerical code called MODFLOW. This
model code is accepted internationally and was also used by the U. S. Geological
Survey in their development of the Salt Lake Valley Ground Water Model. The
model was verified using historical ground watermortitoring data. The
geochemicalmodeling used PI-IREEQC, also widely used. The contaminant
transport was modeled using MT3D. Assumptions are given in detail in the ILI
Report and Appendices.
The time required to remediate the aquifer using the various alternatives was
estimated using the models described above. Although substantial ground water
and aquifer data wereused in the modeling effort, models, by their very nature,
have uncertainties associated with them. For example, the ground water may
encounter a heretofore unknown buffed creek channel which may cause the plume
to change direction and/or flow rate. Therefore, the time required for the plume to
travel and the time for remediation are estimates only. Continued monitoring
would be needed for all the alternatives to detect unexpected results in sufficient
time to plan responses.
36
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F.Current and Potential Future Site and Resource Uses:
1. Land Use:
The contaminated ground water plumes in both Zones A and B underlie a
suburban area of Salt Lake Valley, particularly the eastern portion of the site in
Zone B. The western portion in Zone A is still largely agricultural and mining, but
suburban development pressure is marching westward into this zone too as more
infrastructure such as highways and water service become available. Several 0fthe
cities in the nearby area have already annexed these western lands in anticipation of
the development. A map of current land use is given in Figure 8 (Figure 3-6, from
the Remedial Investigation Report). The Wasatch Front Regional Council
estimates that the population density above the plumes was 1.06 persons/aere in
1998. They estimate that the density will increase three fold by 2020. Growth rate
is estimated at 6% per year for the next 20 years.
2.Ground~surface water uses on the site and in its vicinity:
Current water use: There are three creeks which traverse the two zones from their
headwaters in the Oquirrh Mountains and discharge into the Jordan River. The
Jordan River, in turn, discharges to the Great Salt Lake. Kennecott has a cutoff
wall and reservoir at the mouth of the Bingham Canyon which capture all the flow
of Bingham Creek from the Oquirrhs, in addition to other waters from mining
operations. The water is used in mineral processing at the Copperton
Concentrator. The headwaters of Midas Creek/Copper Creek are now buried by
waste rock from the Bingham Canyon Nfme and waters which formally flowed in
this former drainage have also been diverted by the mining company for use in
mineral processing. The total flow in Buttertield Creek along the southern
boundary of the site is diverted by the Herfiman Irrigation Company and used for
irrigation of agricultural lands and residential yards in and near Herriman. Most of
the creeks are essentially dry by the time they leave the foothills of the Oquirrhs.
The county flood control district has relocated some of them to provide better
drainage following storm events. Flows from the Jordan River are diverted by
canals to irrigation districts. The outfall of’the local waste water treatment plant is
located just downstream of the site on the Jordan River.
There are four cities which overlay the contaminated plumes. Two of the cities,
West ~lordan and Riverton, have their own municipal well fields but also augment
their water supplies with water provided by the Jordan Valley Water Conservancy
District (JVWCD). One of the cities, South Jordan, depends entirely on drinking
water supplied by the JVWCD. The Town of Herriman currently depends on
private wells and a private water supply company, the Herriman Pipeline
Company. There are also some areas which are in unincorporated Salt Lake
39
County. These areas are serviced by private wells, the Copperton Improvement
District, and the Jordan Valley Water Conservancy District.
The Jordan Valley Water Conservancy District obtains its water largely l~om
surface sources outside the site including the Jordanelle, Deer Creek, and Echo
Reservoirs, some high U’mta lakes, the Prove and Weber Rivers, five Wasateh
Front mountain streams, and some Wasateh Front springs, The IVWCD does own
water fights in the affected area. However, these rights have not been developed.
West Jordan’s municipal well field is located just to the north of the acid plume in
Zone Aaud there is coneerrt that excess pumping by the city could draw the
contamination into that direction. Also, there is concern that excess pumping as a
part of any remedy could lower the water table in the area so low as to reduce the
capacity of West Jordan’s wells and other wells in the area.
Riverton’s municipal well field is located just to thesouth of the sulfate plume in
Zone B and one well has already been impacted.
South Jordan has no water rights and has not sought to procure any becauseof the
poor quality water.
The Town ofHerriman’s main water source is the Herdman Pipeline Company
which obtains its water from wells outride the acid plume in Zone A. Town
........... officials are concerned.that the.town will outgrov¢ this.water sourceandnew
supplies may be needed. They are alreadyin negotiations with JVWCD to provide
this additional water. Herriman is largely rural andseveral properties are served by
private wells owned by individuals and small water companies. Several of these
wells have declining water quality.
The Copperton Improvement District well is located outside and upgradient of the
acid plume in Zone A and is not threatened by the contamination.
A summary of the municipal water use provided by the various Suppliers is given in
the following table:
WATER SUPPLIERS AND SOURCES OF WATER
Supplier .Surface water (acre-feet/year) Groundwater (acre-feet/year)
¯
33712Coppe~on
Dansie Water Co (I-Ierriman)
Herriman Pipeline Co.156.3
0
0 75.0
166
40
Suppfier
Hi-Country Estates I
Hi,Country Estates II
Suffaoe water (acre-feet/year)
0
Groundwater (acre-feet/year)
5,217.8 (from JVWCD)
35.6
53.2
Riverton 493.1 (from IVWCD)3,366.3
South Jordan 5,153.3 (from JVWCD)0
West Jordan 6,601..2
The annual water use is 21,631 Acre-ft/yr (1995 data).
The water in the study area is used for a variety ofpurp0ses as approximated in the
following table, from the RI]FS (Water use in units of acre-feet/year):
TYPES OF WATERUSES
Supplier
Copperton
Dansie
Herriman
Hi-Country I
Hi-Country 2
Riverton ..
S. Jordan
W. Jordan
Domestic Commercial
178.0 159.2
36.8
217.9
35.3
3,973.0
53.2
3,471.9 383.6
477.5
Industrial
9,972.3 153.4 1,534.2
Irrigation
3.1
104.4
184.1
Other
33.8
0.3
! , ,
Kennecott conducted a Well Inventory as a part of the Remedial
Investigation/Feasibility Study. Of the 1,688 wells inventoried at the site, 523
were monitoring wells (31%), 559 were in use (33%), and 606 were not in use,
damaged, or missing. Of the 559 wells in current use, 347 were for culinary use
and 212 for other uses. Other uses include irrigation, stock watering, commercial
and industrial uses. When wells of declining water quality were found, KenneCott
worked with the owners to provide alternative water supplies.
41
Anticipated Use: It is quite clear that the water needs of the area wil increase.
Basedon the population growth in the area as estimated by the Wasatch Front
Regional Council, the Jordan Valley Water Conservancy District estimates that the
water demand of their service area will double in the next 20 to 25 years. Their
current water supply for their entire service district is about 70,000 acre-if/yr. By
2020, the district projects it will need about 160,000 acre-if/yr. If the same
growth rate is used for the impacted area, the water needs for population growtla
above the contaminated aquifer could increase from 22,000 acre-t’dyr to 50,000
aere-ft/year. Although the contaminated groundwater is currently not being
utilized except by Kennecott as industrial waters and a few private well owners for
irrigation, full utilization of the impacted groundwater is desired by the cities and
the water purveyors because the water is near the population. Since the safe
annual yield of the aquifer is estimated at 7,000 aere, ft/year, alternative sources of
water from outside the area will be needed as wel.
42
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G.Summary of Site Risks:
1.Summary of Human Health Risk Assessment:
The baseline risk assessment estimates what risks the site poses if no action were
taken. It provides the basis for taking action and identifies the contaminants and
exposure pathways that need to be addressed by the remedial action. This section
of the Record of Decision summarizes the results of the baseline risk assessment
for this site.
For the purposes of this project, a full traditional risk assessment was not
performed. Instead because EPA and UDEQ have adopted drinking water
standards and the ground waters inthe valley are a potential and actual drinking
water source, for most cases the concentrations of the chemicals of concern in the
ground water were simply compared to the drinking water standards. With the
exception of sulfate, which has no primary standard adopted by EPA, any
exceedance of primary drinking standards presents an unacceptable risk to anyone
drinking this water. Because sulfate concentrations are the most pervasive
chemical of concern at the site, the risk assessment focused largely on estimating
the concentration of sulfate that produces unacceptable health impacts to sensitive
populations. A Risk Assessment Task Force, composed of toxicologists and
epidemiologists from EPA, Utah Department of Environmental Quality, Utah
Department of Health, Salt Lake City/County Department of Health, City of West
Jordan, and Kennecott; aided EPA and its contractor in collecting research papers,
evaluating the quality of the re.search, and recommending the level of concern.
a.Identification of Chemicals of Concern: The following table describes the
various concentrations found in the acid plume downgradient of theLarge
Bingham Reservoir:
CONCENTRATIONS OF CHEMICALS OF CONCERN
(From Remedial Investigation Report, Table 4-8; All concentrations are in mg/L unless noted)
Chemical
TDS
bicarbonate
chloride
fluoride
No. of
samples
336
336
58
308
58
Minimum
value
2,,6 ¯
1236
<1.0
41
<0.1
iMaximum
value
6,87
77574
780
539¯
16.2
Mean
4.33
28000
130
190
2.4 "3.8
Std. Dev.
1.22
22000
150
75 0
19
% not I
detected
o
0
44
Chemical No. of Minimum Maximum I Mean Std. Dev.% not
samples -value value detected
sulfate 337 426 59,000 20,000 16,000 .
calcium "280 8 1040 420 -160 0
magnesium 290 127 8640 2600 2200 0
¯ potassium:279 <0.01 70¯
7.2~5.9 .
sodium 290 24 910 100 92 0
nitrate 79 <0.01 4.5 0.67 0.95 ¯41
aluminum 124 <0.005 4690 910 1200 16
arsenic 276 <0.001 4.1 0.040 0.27 38
barium 234 <0.005 0.9 0.024 0.065 51
cadmium 277 <0.001 9.34 0.42 1.1 16 ¯
chromium 234 <0.002 0.99 0.078 0.13 39
copper 277 <0.001 192 47 49¯15
iron 148 <0.01 1222 250 320 5
lead ¯277 <0.001 0.85 0.034 0.13 55
manganese 146 -0.01 1100 180 180 0
nickel 129 <0.01 850 -18 75 3
selenium 277 <0.002 0.9 0.022 0.081 5 ¯
silver 234-<0.001 0.24 0.014 ¯0.030 64|
zinc 239 <0.01 544 69 "68 2
* negative log of H concentration
bold values exceed either a primary or secondary drinking water standard
As demonstrated in this table, the components with maximum
concentrations in the ground water exceeding either a primary or
secondary drinking water standard include pH (acidity), total dissolved
solids, chloride, fluoride, sulfate, aluminum, arsenic, cadmium, copper,
iron, lead, manganese, nickel, selenium, silver and zinc. Even the mean
concentrations of several components exceed primary or secondary
standards, including pH (acidity), total dissolved solids (TDS), fluoride,
45
b°
sulfate, aluminum, cadmium, copper, lead, manganese, nickel, and zinc.
Because the concentration values are widely variable and cart migrate, the
maximum concentration was used for the exposure point assessment.
These concentrations are located in the core of the acid plume.
E~osure Assessment
Potentially exposed popul~’ons in current and.future scenarios:
Currently, the public is not being exposed to the ground waters of the acid
plume. This is because the acid plume is still underneath Kennecott
property currently and Kennecott holds the water fights to this water.
However, if nothing is done to contain the plume in perpetuity or treat it,
the contaminated ground water will continue to move down gr/tdient in the
aquifer eventually leaving Kennecott property: Theoretically, at that time,
any citizen, municipality, or business that has a water fight in the impacted
ground water area could access the contaminated water causing their
household, customers, and workers to be exposed to unacceptable
concentrations of acids, metals, and sulfate in their dfinldng water. If
nothing is done to prevent the continued movement of the plume, more and
more wells in the path downgradient of the plumes would degrade in their
quality. At least one municipal well field, perhaps two, are also threatened.
The situation would only get worse with thepassage of time.
The worst case scenario is theoretically possible. There are currently about
800 water fights holders in this area including two municipalities. Absent
any institutional controls approved by the Utah State Engineer, additional
water fights could be granted and well permits issued to anyone: In
addition, several wells were found where the property owner did not
possess a water fight or a well permit at all. The worst ease scenario is
unlikely because the State Engineer will probably approve institutional
controls to prevent exposure and few citizenswould invest the money to
drill a well in a known area of eontanu’nation.
"Any sensitive populations: There are two populations sensitive to excessive
levels of sulfate, the most pervasive chemical of Concern. Excessive levels
of sulfate in drinking water produces diarrhea, a problem which is
annoying, but not particularly’life threatening, except in infants. Infants
with diarrhea can quickly become dehydrated. For this reason,
pediatricians warn against making infant formula with waters high in
sulfate. Medical evidence shows that adults and older children can build up
a tolerance to high sulfate with repeated exposures. Visitors to any area
with elevated sulfates in the drinking water would feel the effects to a
greater degree than the resident population. Visitors would include
46
HEALTH EFFECTS
household guests, and tourists patronizing local hotels, restaurants, tourist
attractions, and commercial establishments.
Route of exposure: The route of exposure is ingestion of contaminated
ground water for adults, children, infants, and visitors. Other routes of
exposure such as uptake of metals and sulfate from irrigation waters into
garden vegetables, dermal exposure, and inhalation.were not quantified.
Assmnptions: A traditional risk assessment was not conducted for this
operable unit because drinking water standards have already been
developed by EPA and adopted in regulations by the State of Utah.
Therefore, the assumptions used at the site are the. assumptions used to
derive the national and state drinking water standards. It should be pointed
out that some of the drinking water standards are based on more than
health concerns; some include recognition of the treatment technologies
available at the time of promulgation. As a result, some of the drinking
water standards are under review, e.g., for lead and arsenic.
Toxicity assessment
According to the EPA Ottice of Ground Water and Drinking Water, the
effects of drinking water exceeding the primary standards are given in the
following table:
OF ELEVATED INORGANIC COMPONENTS IN DRINKING WATER
Drinking water
component
Arsenic
Barium
Cadmium
Chromium
Potential Health Effects from ingestion of water exceeding the
primary drinking water standard
Skin damage, circulatory system problems, increased risk of cancer
Increase in blood pressure ’
Kidney damage
Allergic dermatitis
Copper Gastrointestinal distress, liver or kidney damage
Fluoride Bone disease, mottled teeth
Lead Delays in mental development, kidney problems, high blood pressure
,,,
Nitrate blue baby syndrome
Selenium hair or fingernail loss, numbness, circulatory problems
47
d
EPA has not yet adopted a federal primary drinking water standard for
sulfate: This is mainly because there is little medical evidence and in some
cases the information is contradictory. The State of Utah adopted a
primary sulfate drinking water.standard of 500 ppm to 1000 ppm,
depending on whether the use was principally residential. The risk
assessment evaluated the available toxicological information and medical
research on sulfate to establish a health based goal for this project. This re-
evaluation was conducted because sulfate is the most pervasive chemical of
concern in the acid plume.
The risk assessment determined that the main effect of elevated
concentrations of sulfate was diarrhea. The effect was short-lived because
people appear to develop a tolerance after about a week of exposure.
Therefore, residents of an area may not show any symptoms of high sulfate
exposure; whereas, visitors to the area could be affected. Although
diarrhea is an annoying condition to adults, it can be potentially dangerous
to infants. Because of their low body weight, diarrhea can cause-
dehydration quickly ininfants. An examination of the literature determined
that few if any effects would occur even to visitors and infants if
concentrations of sulfates are kept below 1500 ppm.
Risk Characterization:.
The concentrations of contaminants in the ground water were compared to
primary drinking water standards and the health based sulfate level which
were used as benchmarks in the following table. In this comparison, the
ratio of the acid plume concentrations to the drinking water standard or
safe level is analogous to a Hazard Quotient.
RISK OF CHEMICALS OF CONCERN IN ACID PLUME
Chemical of Concern Primary Drinking Maximum
Water standard or concentration in acid
health based level
Arsenic 0.05 82
2 0.45 "Barium
Cadmium
Copper
plume (rag/l)
4.1
Ratio
add plume/safe level
(analogous to a
Hazard Quotient)
0.9
=H
0.005 9.34 1868
1.3 (action level)192 147
48
Chemical of Concern
Fluoride
.Lead’.
Nitrate .
Selenium
Nickel
Sulfate
Priory
Water standard or
health based level
(mg/1)
4
0.015 (action level)
10
0.05
Maximum.
concentration in acid
plume (rag/l)
16.2
0.85
4.5
0.9
Ratio
acid plume/safe level
(analogous to a
Hazard Quotient)
4.05
56.6
0.45
18
0.1 (Utah standard)
1500 ppm health-
based level;
500 ppm Utah
primary Standard
85O
59,000
8500
39.3, based on health
based standard;
117.9, based on state
primary standard
In.this case, the ratios (hazard quotients) are not additive since the
contaminants affect different organs and tissues. Most of the metals in the
ground waters within the acid plume are in excess of drinking water
standards, sometimes by a factor of thousands. The predominant exposure
pathway is ingestion of the contaminated ground water.
There are several uncertainties associated with estimation of risk from
exposure to the contaminated ground water of the acid plume. (1) There
are no current exposures to the groundwater. Several private well owners
have already been hooked up to municipal systems. Kennecott has
purchased additional lands to limit access. Therefore, the risk associated
with the plume is a future risk assuming that nothing further will be done.
Because of the complex chemistry which occurs as the acid plume moves
(neutralization, precipitation, redissolution, etc.), the calculations were
based on the current concentrations in the plume, not whatthe plume might
contain in the future. This assumption would likely overestimate future
risk. (2) Drinking water standards are largely health based, but do contain
some consideration for tire drinldng water treatment technologies routinely
available at the time of promulgation. This could mean that the risk could
be underestimated. (3) The scientific literature on the health impacts of
sulfate is sparse and sometimes contradictory. Because of this uncertainty,
EPA has chosen to use a fairly conservative health-based level.
49
2.Summary of Ecological Risk Assessment
The ecological risk assessment estimates what risks the site poses if no aotion were
taken. It provides the basis for taking action and identifies the contaminants and
exposure pathways that need to be addressed by the remedial action. This Section
of the Record of Decision summarizes the results of the Eco!ogieal Risk
Assessment for this site.
In a strategy analogous to the human health risk assessment, the ecological risk
assessment was streamlined and focused on the impacts of ground water recharge
to the Jordan River and additional loads of contaminants that might be expected in
the near and distant future. The concentrations of contaminants in the river with
the projected additional loads were then compared to Utah Water Quality
Standards for the river. The exposure point was assumed to be that stretch of
river that intersects the path of the groundwater flow.
a.Current and near future water quality impacts from ground water:
The ecological risk assessment studies compared the concentrations of
contaminants in the river with,contaminants in nearby monitoring wells to
estimate if any ecological impacts might be present or anticipated in the
near future. The following table gives the results of this investigation
updated with the most recent water quality standards.
COMPARISON OF WATER QUALITY IN WELLS WITH JORDAN RIVER WATER
QUALITY STANDARDS (Updated from RI/FS)
Jordan River Narrows to Little Cottonwood Creek segment
Contaminant Jordan River,Concentrations in Utah Water Quality
concentrations nearby ground water Standards for Jordan
wells River segment (4- ,
day, aquatic life 3a
class)
TDS 973 mg/l (upstream)not given 1200 ppm ’
1135 mg/1 (agricultural use
(downstream)standard, none for
aquatic life)
Cadmium 2.0 ppb or less <2.0 ppb 1.1 ppb
Copper 20 ppb or less 19 ppb 12 ppb
Selenium <3 ppb 9 ppb 5 ppb
50
Contaminant
Zinc
Sulfate
Jordan River
concentrations
11 ppb
248 mg/1 (upstream)
309 mg/l
(downstream)
Concentrations in
nearby ground water¯
wells
252 ppb
432 mg/l
Utah Water Quality
Standards for Jordan
River segment (4-
day, aquatic life 3 a
class)
110 ppb
’ "i
no standard-
calculated from
literature 505 mg/1
The concentrations in the ground water of wells near the Jordan River
exceed the Utah Water Quality Standards for the Jordan River for copper,
selenium, zinc, and perhaps others. After mixing with other waters in the
river, the concentrations in the river may eventually exceed the standard in
thenear term but not excessively so. Kennecott asserts that the
contaminants do not come from mining activity but l~om irrigation and
other sources.
b.Sources of water to the Jordan River segment of interesl:
Although the average flow of the Jordan River during the irrigation season
has been estimated near Utah Lake at 204,000 gpm, nearly 100% of the
river is diverted by irrigation canals during the irrigation season. The
average flow of the river near the site (9000 South) is 40,000 gpm during
irrigation season. The ground water model results suggests that 21,400
gpm (53%) of this flow originates from ground water discharge from the
western part of the valley (the location of this site), 7,200 gpm (18%) from
the eastern side of the valley, and 11,800 gpm (29%) from return flow from
the irrigation canals.
c.Future ecological risk:.
Although the current or near term risk appears to be low¯for the
contaminants associated with the ground water, a different picture
altogether emerges if the acid plume is allowed to reach the Jordan River.
Ground water modeling suggests that this could occur in 150 years if
nothing is done to contain the plume. The following table illustrates what
could happen in this circumstance.
51
POTENTIAL CONCENTRATIONS OF CONTAMINANTS IN JORDAN RIVER IF ACID
PLUME IS NOT CONTAINED (updated from the RI Report)
Contaminant Average Average Jordan River Water Ratio of
Jordan River " concentration after mixing Quality future lordan
concentration in acid plume with acid Standard (4-River to
(average of (1997)plume day, aquatic standards
upsteam and (assuming a class 3a,
downstream)1:20 mixing Jordan River)
ratio, year
round)
Sulfate.278 mg/l 18;000 mg/l 1039 mg/l no standard,2.06
505 mg/1
calculated
from
literature
TDS 1054 mg/l 25,000 rag/1 2195 mg/l 1200 mg/1,1.83
agricultural
use standard
Cadmium <2ppb 620 ppb.29.1 ppb.1,1 ppb 26.4 - "
Copper <20 ppb 41,000ppb 1818 ppb 12ppb 151.5
Selenium <3ppb 14ppb 4,3 ppb 5.0 ppb 0.86
Zinc 11 ppb 67,000 ppb 2933 ppb 110 ppb 26.7
This calculation demonstrates that the water quality of the Jordan River
would decline seriously should the acid plume be allowed to reach the
river. The situation is actually worse during irrigation season when there is
essentially no dilution factor available because the flows in the river are
less.
Uncertainties:
The uncertainties inherent in these calculations are numerous. The
assumptions are particularly uncertain. (1) This calculation assumes that
the acid plume will eventually reach the Jordan River. However, the acid
plume is in the principal aquifer rather than the shallow aquifer. It is
known that the shallow aquifer discharges to the river. The principal
aquifer may go underneath it or discharge to it at a much slower rate. The
calculations, therefore, represent a worst case scenario. (2) This
52
o
calculation assumes that the average concentrations in the acid plume
currently would reach the river with its concentrations unmodified by
dispersion or reactions with the aquifer solids. This is very unlikely. By
the time the acid plume reaches the river, concentrations of contaminants
are likely to be much less. Again, the calculations represent a worst case
scenario. (3) These calculations assume that the water quality in the river
will remain the same in the future as they are today. Although improving
water quality in the river will not help much if the acid plume does reach
the river, declining water quality in the river could make the situation
worse. (4) The mixing ratio varies seasonally. The calculations represent
the annual average. During irrigation season the influence of ground water
on the Jordan River is much more inaportant than during the rest of the
year. (5) The ground water flow rates to the river are based on the ground
water model for the site and, therefore, are affected by the uncertainties
associated with the use of the model. These uncertainties are just a few
examples of the ditiieulties in estimating risk far into the future.
Basis for action
Absent limitations on access to the ground water, human health could be at risk to
anyone seeking to use the water for culinary purposes. The water quality fails to
meet primary standards and health based levels. It is also not suitable for
municipal supplies without treatment because it violates a host of secondary
standards. /n some eases the water is unuseable even for secondary uses such as
irrigation due to its acidity.
If nothing is done, the acid plume will continue to move toward the Jordan River
where it Could impact the Jordan River’s aquatic life, perhaps severely.
53
Remedial Action Objectives"
.
h/finimize or remove the potential for human risk (by means of ingestion)by
limiting exposure to ground water containing chemicals of concern exceeding risk-
based concentrations or drinking water Maximum Contaminant Levels.
a.Human health risk is minimized by either reducing the contaminant levels
or cutting off the exposure pathway.
b°Contaminants, which could be ingested, can be decreased by reducing the
concentrations in the aquifer itself to drinking water standards or treating
the ground waters to drinkingwater standards before it is used.
.
c°The exposure pathway can be cut by limiting access to the ground water
and obtaining water from another source.
1Wmimize or remove the potential for environmental risk (by means offl0w of
ground water to the Jordan River) to receptors of concern.
a.Ecological risk is minimized only by reducing the contaminant levels.
b°Contaminant levels could be decreased only by reducing the concentrations
in the aquifer itself.
3.Contain the acid plume and keep it from expanding.
a°
b°
c°
Containment of ground water plumes is the expected minimum forground
Water actions in the National Contingency Plan.
Allowing the plume to move farther will contaminate additional ground
water, including at least one municipal well field, and damage additional
aquifer materials.
Maintain sulfate-laden groundwater in excess of 1500 mg/1 west of the
Kennecott property line in Zone A~
4.Remediate the aquifer over the long term
a;Ground water in this aquifer is a resource that is needed by the public both
now and in the future as communities grow westward toward the Oquirrh
Mountains.
54
o
,b.Remediation is the only long term option which is totally effective in
preventing the public from exposure to dangerous levels of contaminants in
this ground water.
Return ground water to beneficial use.
ao
b°
Return of ground water to beneficial use is an expectation of the National
Contingency Plan.
The site is located in a semi-add climate. Ground waterresources are
needed to support additional population and development growth
projections for the site.
55
L Description of Alternatives
The Remedial Investigation/Feasibility Study evaluated six (6) alternatives.- A number of
others were rejected in the screening process. A summary of each of the six retained alternatives
is given below:
1.Alternative 1 - No Further Action.
This alternative relies solely on natural attenuation to achieve long term
remediation goals. This could take 800 years or longer. Citizens and
municipalities wouldbe responsible for limiting their own exposures.
Major elements of Alternative 1:
Maintenance of source controls already implemented by Kennecott:
(Kennecott has constructed a system to collect acid rock drainage which
continues to emanate from theirwaste rock dumps. This must be
maintained in order to prevent additional contaminants from entering the
ground water.)
Monitoring effectiveness of source controls as required in a State
Groundwater Permit: (The state has issued a Ground Water Permit to
Kennecott whichrequiresKennecott to monitor wells downgradient of
their source controls to demonstrate that the controls continue to prevent
further contamination.)
Monitoring migration of the plume: (A monitoring network has been
installed. In this alternative, movements of the plume could be determined
and water users warned of the arrival of the acid plume.)
b.Key ARARs:
Continued participation in the State Ground Water Protection Program
which requires the operations and maintenance of the source control
measures is required. After mine closure the operations and maintenance
of the source control measures must be maintained, perhaps as an element
of the 1Wine Closure Plan administered by the Utah Division of Oil, Gas and
Mining. In addition, chemical specific standards would be ARARs, but
they would not be met.
56
c.Longterm reliability:
The source control measures are well constructed and are likely to be
reliable in the long term.
Quantity of untreated waste and treatment residuals:
Because there is no treatment, the quantity of untreated water actually
grows as the plume gets further dispersed over time. There would be no
treatment residuals as a result of this option other than those associated
with source control.
e.Estimated time for design and construction:
The source control measures are already designed and constructed.
f. Estimated time to reach remediation goals:
None of the goals would be achieved for at least 800 years, perhaps longer.
g. Estimated costs: (Appendix M, RUFS)
ESTIMATED COSTS FOR ALTERNATIVE 1
Activity Capital costs O+M costs for 30 net present
years value
Source controls (already $127M already $19.2M $19.2M
implemented by Kennecott)expended, not
included in cost
Monitoring $7.1M $7.1M
TOTAL (diseoum rate = 7%)$26.3M $26.3M
h,Use of presumptive remedies or innovative treatment:
No presumptive remedies or innovative treatment technologies areused in
this alternative.
57
i.Expected outcome:
This alternative relies entirely on natural attenuation leaving the public and
municipalities to their own devices to prevent exposure. Eventually when
the plume reaches the Jordan River, the aquatic ecosystem might be
severely impacted.
Alternative 2 - Institutional Control~.
This would seek to prevent exposure to the public, but does nothing to contain or
treat the plume itself.
a.Major elements of Alternative 2
Restrictions on use of existing wells, as approved by the Utah State
Engineer: (Measures include purchase of land and water rights; restrictions
on land use to prevent use of wells through codes, covenants; and
restrictions by either municipal, county or state government)
Restrictions on drilling of new wells, as approved by the Utah State
Engineer: (Purchases of water rights and land; restrictions on land use to
prevent drilling of wells using codes, covenants, and restrictions by either
municipal, county or the State Engineer.)
Modifications of above restrictions as the plume migrates in the future
¯Includes the measures in Alternative I.
b.Key ARAR~.
In addition to ARARs from/X~lternative 1, the key ARARs in this case
would be the various Utah Water Rights Laws, UtahWell Drilling
Regulations, and local building codes.
c.Long term reliability:
This relies on the citizens to conform to the letter and spirit of all
restrictions that might be placed on them by their local governments and by
the State Engineer. This is very unlikely. Circumvention of the water
fights regulations and local ordinances is rather common because citizens
view these as an infringement on their property rights. Enforcement would
be very difficult. Although this might work temporarily, it would not be
very reliable in the long term.
58
d.
f
g.
Quantity of untreated waste arm treatment residuals:
Since there is no treatment the quantity of untreated water actually grows
as the plume gets further dispersed over time. There would be no
treatment residuals other than associated with source controls.
Estimated time for design and construction:
It is estimated that two years would be required to get all of the
institutional controls in place.
Estimated time to reach remediation goals:
Although people might not.be exposed to contaminated water, the plume
continues to move eventually reaching the Jordan River. It could take 800
years for the contaminated plume to be flushed through the aquifer.
Estimated costs: (Appendix M, RI/FS)
ESTIMATED COSTS FOR ALTERNATIVE 2
Activity
Activities in Alternative 1
Water fights and land purchase
TOTAL
Capital costs
¯$16M (2 years)
$16M
O+M costs for 30
years
net present
value
$26.3M $26.3M
$16.5M
$26.3M ~2.3M
h°Use of presumptive remedies or innovative treatment:
No presumptive remedies or innovative treatment technologies are used in
this alternative.
Expected outcome:
This alternative relies on natural attenuation but does prevent exposures to
the public by limiting access to the water. When the plume reaches tbe
Jordan River the aquatic life could be impacted, perhaps severely. The
success depends on the cooperation of municipal, local and state
government and all the citizens to cooperate with the regulations. This
cannot be guaranteed in perpetuity.
59
.
Alternative 3 - Point of Use Management:
This alternative seeks to prevent exposure to the public but does nothing to
contain or treat the plume itself.
a.Major elements of Alternative 3:
Replace impacted private well water by connecting residences to existing
municipal water supply systems. (Instead of simplybanning further use of
wells, private well owners are given replacement water from municipal
systems with waters unaffected by the plume. Wells can still be used to
provide irrigation water if the values are less than 1500 ppm sulfate.)
Install household water treatment units (suchas reverse osmosis) to treat
water supplied to residences by private wells: (When municipal systems are
not available, treatment of the private well water can be provide with in-
home treatment units. Wells can still be used_without treatment to provide
irrigation water, if the values are less than 1500 ppm sulfate.)
If municipal systems are impacted in the future, alternative water supplies
would be required or a treatment plant installed: (Modeling suggests that
the plume might impact at least one municipal well field: If this occurs, it
will be necessary to build a treatment plant for these wells.)
Includes all the measures in Alternatives 1 and 2.
b.Key ARARs:
In addition to the AGARS in Alternative 2, the key ARAK in this
alternative would be the Utah Drinking Water regulations which apply to
municipal services and drinkingwater quality at the tap.
C.Long term reliability:
?
Hooking people up to municipal supplies has long term reliability although
there could still be exposure to residents with wells since the wells would
not be shut off. Limitations on the kinds of uses would work for the
current well owner, but may not be passed on to new owners. Because this
would be necessary for a long period of time, there could still be occasional
exposure. In-home treatment units require some effort on the part of the
resident to maintain the units and replace them when necessary.
Information about the need for this treatment might not be.passed on to
any new owners. In-home treatment systems would not work should the
60
d
f.
g.
acid plume core reach a private well. This alternative does nothing to clean
up the aquifer itself.
Quantity of untreated waste and treatment residuals:
Although there would be some treatment residuals produced vdthin the in-
home treatment units, the amount would be minimal and would end up
with the trash at amunidpal landfill. The quantity of untreated waste
actually increases as the plume continues to spread out contaminating more
and more water as it moves downgradient.
Es- timated time for design and construction:
It might take two years to locate all the affected parties, design extensions
to public water systems, and install in-home systems. Evaluation of the
plume movement patterns would continue indefinitely to observe and
mitigate future impacts as the plume moves.
Estimated time to reach remediation goals:
Although exposure to the public would be minimized in the short term, this
alternative does nothing to remediate the aquifer. The plume would
continue to move unimpeded toward the Jordan River where impacts might
occur, perhaps severe impacts. The aquifer would take 800 years or longer
to flush through the environment.
Estimated costs: (Appendix M, RI/FS)
ESTIMATED COSTS FOR ALTERNATIVE 3
Activity
Activities in Alternatives 1 and 2
Municipal connections
Household treatment units (400)
TOTAL (7% discount)
Capital costs
$16M
$0.901M
$0.618M
$17.6M
O+M costs for 30
years
$26.3M
not estimated
. $0.64M
$27.2M
net present
value
$42.3M
$0.901M
$1.3M
$44.8M
61
4.
h.Use of Presumptive remedies or innovative treatment:
There are no presumptive remedies or innovative treatment technologies
used in this alternative.
Expected outcome :
Private well owners would be protected from exposure to unacceptably
high concentrations of contaminants in their well water because an
alternative source of culinary water would be provided. The well owners
could continue to use their wells for irrigation purposes, but could be
exposed if they used the water inappropriately. Institutional controls
would have to be in place, essentially in perpetuity to verify that well water
is used properly. New owners m~y not be made aware of the problems.
This alternative would do nothing to prevent the plume from eventually
reaching the Jordan River perhaps causingsevere impacts. Alternative 3
would do nothing to remediate the aquifer: Fresh water recharges would
also become contaminated as they encounter the plume and the
contaminated alluvium: The plume could take 800 years or longer to
course through the system.
Alternative 4- Hydraulic Containment, Reverse Osmosis (RO) Treatment,
Delayed Acid Plume Extraction, Nanofiltration (NF) Treatment and Delivery of
treated water:
Alternative 4 seeks to prevent exposure to the public, contain the contaminated
water and eventually treat the contaminated plume.
Major elements of the alternative:
Installation of a barrier well containment system at the leading edge of the
acid plume: (The barrier well system seeks to prevent further downgradient
migration of the plume.)
Treatment of the water using reverse osmosis (RO) for the first 10 years:
(The waters would initially be high in sulfate which could be treated
successfully with RO. In 10 years, the core-of the acid plume would
migrate to the wells and RO would not be able to work, due to high
concentrations of sulfate, heavy metals and acid..)
After the first I0 years, pretreatment of the water will be necessary as the
core of the acid plume migrates to the barrier well system: (Membrane
technology, such as Nanoftltration (NF) is proposed for pretreatment. As
62
b.
C°
d.
e°
the highly acidic waters encounter the barrier wells, pretreatment of the
water to reduce contaminant concentrations will be necessary before it is
sent for polishing at the RO plant.)
Treated water would be delivered to a municipal water purveyor.
Concentrates would be discharged into Kennecott’s railings line Or into
Kennecott’s mineral processing water circuit.
Includes all the measures in Alternatives t, 2, and 3.
Key ARARs:
In addition to ARARs in Alternative 3, key AR~Rs include the Utah
Drinking Water Regulations, Utah Public Water Supply requirements, the
Utah Ground Water Protection Corrective Action program, RCRA, the
Utah Pollutant Discharge Elimination Program permit regulations, and
Utah Water Rights Laws.
Long term reliability:
While preventing exposures to water users downgradient, this alternative
incorporates a barrier well system which would seek to prevent further
downgradient migration of the plume. The long term reliability of the
barrier system is questionable because the highly acidic waters eventually
encounter the barrier wells and any leakage past these wells would cause
significant amounts of contaminants to escape downgradient. However,
the technology, reverse osmosis with nanofiltration pretreatmenL has been
shown in pilot tests to work on the plume and could be reliable with proper
maintenance.
Quantity of untreated waste and treatment residuals:
Atthe end of the remedial action, there should be no untreated wastes.’ If a
pumping rate of 3500 gpm is assumed, treatment residuals could be as high
as 2100 gpm over the life of the project. Existing infrastructure for
management of treatment residuals would be available so long as the
mining operations continue. Other methods of disposal for treatment
residuals would be necessary following mine closure.
Estimated time for design and construction:
The entire remedy would not be in place for 10 years. A monitoring
63
f.
g.
system would also be needed to ensure that leakage past the barrier wells is
not occurring.
Estimated time to reach remediation goals.
Containment of the plume might be achieved quickly and prevention of
exposure to humans and the aquatic species in the’Jordan River would also
be achieved quickly. The time required to remediate the aquifer could be
150 years or longer.
Estimated costs (Appendix M, RI/FS)
ESTIMATED COSTS FOR ALTERNATIVE 4
Monitoring, Institutional Controls,
Point of Use Management
(Alternatives 1 - 3)
Installation of barrier wells, pump
stations and infxastructure
Reverse Osmosis facility
Nanofiltration pretreatment plant
after first 10 years
Additional barrier wells and
upgrades after first 10 years
TOTAL (7% discount)
Capkal costs
$17.6M
$20.8M
$23.3M
$30.M
$21.8M
$86.2M
O+M costs for 30
years
$27.2M
$65.4M
Part of
¯infrastructure
O+M
$38.4M
Part of
infrastructure
O+M
$103.8M
net present
value
$44.8M
$86.2M
$23.3M
$68.4M
$21.8M
$217.2M
h.Use of presumpfive remedies or innovative treatment:
This alternative does¯not use presumptive remedies. Membrane technology
such as nanofiltration is still considered innovative because a number of the
operational details and O+M requirements have not yet been fully worked
out.
64
5
Expected outcome:
Citizens are protected from exposure to contaminants and the acid plume
never reaches the Jordan River. The ground water is cleaned up over time
and is returned to beneficial use. Continued monitoring would be
necessary to verify barrier well effectiveness.
Alternative 3 - Hydraulic Containment, NF Pretreatmeni~ RO Treatment, Active
Pumping of the Core of the Acid Plume and Delivery of the treated water:
Alternative 5 has two well systems, one for containment of the plume at the plume
boundary and another for withdrawal of acidic waters from the core of the plume
to begin the remediation of the aquifer. People are prevented from being exposed
during the projectby point of use management and treated water is provided to
communities.
a,Major elements of Alternative .5:
Installation of a barrier well containment system: (The barrier well system
collects contaminated waters (primarily sulfate laden) at the leading edge of
the plume preventing further migration of the plume. Traditional RO
treatment can be used.)
Installation of a well or wells in the core of the acid plume so that highly
acidic waters do not migrate to the barrier wells and remediation of the
acid plume can begin quickly: (Modeling suggest that pumping from the
core would prevent the acid plume from approaching the barrier well
system. Any migration of the acid water beyond the barrier wells could
cause severe degradation of ground water quality. With these upgradient
core plume wells, the barrier wells become a safety net rather than the
primary containment system.)
Pretreatment ofaeid waters using nanofiltration: (Waters from the core of
the plume are too high in dissolved solids to be treated efficiently with
reverse osmosis. Membranes would elog too quickly. Nanofiltration has
been shown to work on a pilot scale using acid leachate waters from the
site. Operational details need some refinement.)
Treatment of pretreated core waters and barrier well sulfate waters by
reverse osmosis: (Treatment and polishing of waters would be
accomplished using traditional RO technology.)
65
b.
C.
d
eo
Treated water is delivered to a municipal water purveyor, as a requirement
under the NRD action.
Pre-mine closure, treatment concentrates are disposed by insertion into
Kennecott’s railings line or into Kennecott’s mineral processing water
circuit.
Includes all the measures in Alternatives 1, 2, and 3.
Key ARARs:
In addition to ARARs in Alternative 3, key ARARs include the Utah
Drinking Water Regulations, Utah PublieWater Supply requirements, the
Utah Ground Water Protection Corrective Action program, RCRA, the
Utah Pollutant Discharge Elimination Program permit regulations, and
Utah Water Rights Laws.
Long term reliability:
While preventing exposures to the public downgradient, this alternative
provides a dual containment system. The acid wells would withdraw
waters from the core of the plume. Drawdowns within the aquifer caused
by this pumping should theoretically stop all eastward movement of the
plume. The barrier wells along the front of Zone A would provide a safety
net to stop less concentrated materials from escaping downgradient. The
technology has been shown in preliminary pilot tests to work on the plume
and, with proper maintenance, the technology will be reliable.
Quantity of untreated waste and treatment residuals:
At the end of the remedial action, there should be no untreated wastes. If a
combined barrier well/acid well pumping rate of 3500gpm is assumed,
treatment residuals could be as high as 1300 gpm over the life of the
project. Existing infrastructure for management of treatment residuals
¯ would be available so long as the mining operations continue. Other
methods of disposal for treatment residuals would be necessary following
mine closure. A plan will be developed using current technology as a part
of the Remedial Design which can be implemented immediately, with the
understanding that a different strategy can be used upon approval by EPA
and UDEQ using technology available at the time of mine closure.
Estimated time for design and construction:
66
Construction completion is estimated to take 5 years. Design and
experimentation with treatment parameters could take 1.5 years of this.
f.Estimated time to reach remediation goals:
Containment of the plume could be achieved quickly and prevention of
exposure to people in the affected area and the aquatic species in the
Jordan River could also be achieved quickly. The time required to
remediate the aquifer could be 150 years or longer. Modeling suggests that
the original core of the acid plume would be largely removed in the first 30
years. However, withdrawals and treatment would have to continue for a
long time as components in the solid phase of the impacted aquifer
materials begin to re-dissolve back into the water as the fresh water flows
through the contaminated aquifer material. The time it would take to
achieve a total cleanup is unknown. Further modeling and monitoring may
give insights on progress as the project continues.
g.Estimated costs: (Appendix M, RUFS)
ESTIMATED COSTS FOR ALTERNATIVE 5
Activity
All the measures in Alternatives 1,
2, and 3
Installation of a barrier well
containment
¯ Withdrawal from the core of acid
plume and Pretreatment 0fthis
acid water using NF
Treatment ofpretreated acid
waters by reverse osmosis
Treatment of sulfate waters from
barrier sulfate wells by reverse
osmosis
Treated water is delivered to a
municipal water purveyor
Capital costs
$18M
$8198M
$23.1M
$2.9M
$17.5M
included in
treatment
O+M costs for 30
years
$27M
$19.23M
$33.9M
Included in RO
costs
$21.3M
included in
treatment
net present
value
$45M
$28.11M
$47.0M
$2.9M
$38.8M
included in
treatment
67
Activity ¯ " :
Concentrates are disposed in
Kennecott’s tailings line
TOTAL
Capital costs
$4.4M
$74.5M
O+M costs for 30
years
$21.0M
$122.7M
net present
value
’ $25.4M
$197.2M
h.Use of presumptive remech’es or innovative treatment:
This alternative does not use presumptive remedies. Membrane technology
such as nanofiltration is still considered innovative because a number of the
operational details and O+M requirements have not yet been fully worked
out. Disposal of the treatment residuals into the existing tailings pipeline is
also innovative. It takes advantage of the neutralization capacity of the
tailings in a 13-mile long pipeline to neutralize the treatment concentrate
and precipitate out the metals. Because it takes advantage of existing
infrastructure of the mill, it is also very cost effective.
i.Expected outcome:
citizens are protected from exposure to contaminants and the acid plume
never reaches the Jordan River. The aquifer is cleaned up over time.
Based on modeling predictions, most of the cleanup occurs while the
mining operations continue so existing infrastructure can be used. The
ground water is returned to beneficial use.
6 Alternative 6 - Hydraulic Containment, N’F Pretreatment, RO Treatment, Active
Pumping of the Acid Plume and Lime Treatment of Treatment Residuals
cL Major elements of Alternative 6:
Same as Alternative 5, except acidic waters are withdrawn from the
aquifer, treated with NF and the treatment concentrate is treated with lime.
Two waste streams are generated: solid residuals from lime treatment and
the water which is not delivered to the public but is used as process waters
by.Kennecott. The RO plant treats only the waters from the barrier wells,
not waters from the core of the plume.
Standard technology for lime treatment of acid rock drainage used by the
mining industry is used instead of more innovative technology such as
treatment in the tallings pipeline.
¯Treatment residuals from lime treatment of the nanofiltration
68
concentrations are stored in a lined repository located close to the
treatment plant.
d
e°
f.
Key ARARs:
In addition to ARARs in Alternative 5, key ARA~ include the Utah
Drinking Water Regulations, the Utah Ground Water Protection
Corrective Action program, Utah Water Rights Laws and the Utah
Pollutant Discharge Elimination Program permit regulations. Depending
on the composition of the lime wastes, RCRA Hazardous Waste
regulations are relevant and therefore influence the design of the
repository. It would also need to meet the substantive requirements of the
Utah Ground Water Protection Program.
Long term reliability:
While preventing exposures to the public downgradient, this alternati~ee
provides a dual containment system. The wells in the core of the acid
plume would withdraw highly contaminated ground water. Drawdowns
within the aquifer caused by this pumping should theoretically stop all
eastward movement of the plume. The barrier wells of the acid plume
would providea safety net to stop less concentrated materials from
escaping downgradient. The lime treatment technology is not innovative
and has been used with reliability in the mining industry for years.
However, it does present a disposal problemfor the solid wastes produced
by the lime treatment.
Quantity of untreated waste and treatment residuals:
At the end of the remedial action, there should be no untreated wastes. If a
combined barrier well/corewell pumping rate of 3500 gpm is assumed,
treatment residuals could be as high as 240,000 tons/year.
Estimated time for design and construction:
Construction completion is estimated to take 5 years. Design and
experimentation with treatment parameters could take 1.5 years of this.
Estimated time to reach remediation goals:
Containment of the plume could be achieved quickly and prevention of
exposure to people in the affected area and the aquatic species in the
69
1ordan River would also be achieved quickly. The time required to
remediate the aquifer could be 150 years or longer. Modeling suggests that
the original core of the acid plume would be largely removed in the first 30
years. However, withdrawals and treatment would have to continue for a
long time as components in the solid phase of the impacted aqffffer
materials begin to re-dissolve back into the water as clean water flows
through the contaminated aquifer material. The time it would take to
totally cleanup the ground water and the aquifer materials is unknown,
Estimated costs
ESTIMATED COSTS FOR ALTERNATIVE 6
Activity O+M/30 years
$122.7MAlternative 5 (except method for
disposal of treatment residuals)
Treatment residuals treated with
lime and sludge removal
[’ .
TOTAL "
Capital Costs
$74.5M
$13.2M
$87.7M
$149.8M
¯ $272.5M
net present
value
$197.2M
$163.2M
$360.4M
h.Use of presumptive remedies and innovative treatment:
This alternative does not use presumptive remedies. It uses art innovative
membrane technology (nanofiltration) treatment for the acid waters.
i.Expected outcome:
Citizens are protected from exposure to contaminants and the acid plume
never reaches the Jordan River. The aquifer is cleaned up over time. The
ground water is returned to beneficial use. The volume of lime required
using this approach would be large leading to a great increase of traffic in
the area. A regulated retention structure for the sludge would be needed,
Ancillary alternatives for special situations
Alternatives for NF concentrate disposalfollowing cessation of mining
and milling operations in 30 years (railings pipeline would no longer have
railings flows). These apply to Alternatives 4 and 5.
¯Pump the concentrate to a lined facility on the waste rock dumps for
70
b.
C.
evaporation, disposal of the sludges in the dump or in a lined storage
facility.
Use the former tailings pipefine or another dedicated pipeline to convey
concentrate to shallow ponds on the top of the new railings pond for
evaporation. Lining depends on the characteristics of the residuals.
Same as above, but ere, ate solar ponds to create electricity. Electricity
could be used to help evaporate water during the winter months. Sludge
storage is also necessary.
Lime treatment and disposal of residuals in an on-site RCRA-I~e
r~ository.
Alternative for RO concentrate disposal following mine closure m 30
years (this applies tO Alternatives 4, 5 and 6):
Direct disposal in the Great Salt Lake via a new pipeline and outfall. This
depends on the nature of the concentrate and impacts on the Great Salt
Lake
Evaporation ponds
Alternatives for well-head protection
Because there is a poss~ility that water level drops might affect municipal
and private wells throughout the area, additional alternatives for Well Head
Protection were developed. In the case of Alternatives 1, 2, and 3, these
might be needed to protect wells from beingimpaoted by contaminated
water as theplume moves through. In the case of Alternatives 4, 5, and 6,
this is needed to prevent wells from going dry as the acid plume in Zone A
is ~tggressively pumped out of the aquifer. These measures might also be
needed if the barrier well system is ineffective in totally containing the
plume.
For the West Jordan municipal well field:
¯Install injection wells between the acid plume and the West Jordan
municipal well field. (This requires permission from UDEQ.)
¯Inject strfticient water into aquifer to prevent excessive water level
drops near West Jordan well field and prevent acid plume migration
in that direction. (This requires permission from UDEQ.)
¯Water would come from uncontaminated sources of water in the
nearby mountains.
71
If draw downs are the main problem, storage of water in the winter
months in above ground tanks instead ofreinjection.
For private wells:
*Hook up to municipal water.
¯Installation and maintenance of a residential reverse osmosis
treatment system if municipal water hook up is impractical.
-Deepening of the affected well if it is thought that a deeper well
would yield sufficient replacement water.
¯Replacement of water using other sources.
¯Underground injection up gradient of affected wells to
counterbalance the drops. (This requires permission ~om UDEQ.)
72
Summary of Comparative Analysis of Alternatives:
The National Contingency Plan (NCP) requires that the various remedial action
alternatives be evaluated individually and then compared relative to each other using nine
criteria. The nine criteria in the National Contingency Plan and how the alternatives
compare are described below:
1.Overall protection of human health and the environment
Overall protection of human health and the environment addresses whether each
alternative 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, and/or institutional
controls.
Alternatives 2, 3, 4, 5, and 6 all protect human’health. Alternatives 4, 5, and 6 use
institutional controls to limit exposure ofhumans to the contaminated ground
water while the aquifer itself is being restored. In Alternatives 2 and 3, human
health is also protected by limiting exposure of the public to the contaminated
waters through the use of institutional controls. For these alternatives, institutional
controls are the sole mechanism of prevention both short term and long term.
Alternative 1 does not protect human health.
Alternatives 4, 5, and 6 protect the environment by preventing migration of the
plume. The plume never reaches the Jordan River where exposure to aquatic life
could occur.
Alternatives 1, 2, and 3 do nothing to contain the plume or prevent it from
reaching the Jordan River. They would not protect the environment.
2.Compliance ~vith Applicable or Relevant and Appropriate Requirements
CERCLA and the NCP require that remedial actions at CERCLA sites at least
attain legally applicable or relevant and appropriate Federal and State
requirements, standards, criteria, and limitations which are collectiVely referred to
as ARARs, unless such ARARs are waived under conditions outlined by
CERCLA.
Applicable requirements are those cleanup standards, standards of control, and
other substantive requirements, criteria, or limitations that are promulgated under
Federal environmental or State environmental or facility siting laws. These
regulations specifically address a hazardous substance, pollutant, eontaminanL
remedial action, location, or other circumstance found at a CERCLA site. Only
73
3.
4.
those State standards that are identified by a state in a timely manner and that are
more stringent than Federal requirements may be appficable. Relevant and
appropriate requirements are those cleanup standards, standards of control, and
other substantive requirements, criteria, or limitations that are promulgated under
Federal environmental or State environmental or facifity siting laws. These
requirements; while not applicable to a hazardous substance, pollutant,
contaminant, remedial action, location, or other circumstance at a CERCLA site
do address problems or situations sufficiently similar to those encountered at the
CERCLA site that their use is well-suited to the particular site. Only those State
standards that are identified in a timely manner and .are more stringent than Federal
requirements may be relevant and appropriate.
The NCP Criterion of compliance with ARARs addresses whether a remedy will
meet all &the applicable or relevant and appropriate requirements of other Federal
and State.environmental statutes or provides a basis for invoking a waiver.
Alternatives 4, 5, and 6 would comply with ARARs through appropriate designs.
Alternatives 1 - 3 would not comply with chemical specific ARARs
Long Term Effectiveness and Permanence
Long term effectiveness and permanence refers to expected residual risk and the
ability era remedy to maintain reliable protection of human health and the
environment over time, once clean-up levels have been met. This criterion includes
the consideration of residual risk that will remain onsite following remediafion and
the adequacy and reliability of controls,
All alternatives, except the no action Alternative t, provide some degree of long
term protection. Alternatives 4, 5, and 6 offer a permanent cleanup of the aquifer
allowing eventually the full use of the ground water resource. The Jordan River
would be protected by the remedial action preventing the migration of the plume.
Alternatives 2and 3 can be effective but access to the contaminated ground water
by use of water rights and the eireaunvention of the institutional controls is
possible. The Jordan River would not be protected by these two alternatives.
Alternative 1 provides no protection at all to either the public or the Jordan River.
The plume would continue to migrate, contaminating the aquifer further and
causing the cleanup time to increase.
Alternatives 4, 5, and 6 would produce some form of treatment residuals which
would require proper handling and maintenance to maintain effectiveness.
Reduction of Toxicity, Mobility, or Volume through Treatment
74
5.
6.
Reduction of toxicity, mobility, or volume through treatment refers to the
anticipated performance of the treatment technologies that may be included as part
of a remedy.
Alternatives 4, 5, and 6 all use treatment technologies that would reduce toxicity,
mobility and volume of the contaminated ground water. Although Alternative 3
uses in home treatment technology, the purpose is not treatment of the aquifer
itself and does not reduce toxicity, mobility or volume. Alternatives 1 and 2 do
not involve any treatment at all and would not reduce toxicity, mobility and
volume of the contaminated plume. In fact it is likely thaf the volume of
contaminated ground water would actually increase under Alternatives, 1, 2, and 3.
Short term effectiveness
Short term effectiveness addresses the period of time needed to implement the
remedy and any adverse impacts that may be posed to workers, the community and
the environment during construction and operation of the remedy until cleanup
levels are achieved.
Alternatives 2, 3, 4, 5 and6 would be effective in the short term because all of
these alternatives depend, inthe short term, on limiting exposures to humans via
institutional controls. Alternatives 3, 4, 5, and 6 are enhanced by providing
alternative sources of water to those whose wells are limited by the controls.
Alternative 1 is not effective, short term or long term.
lmplementability
Implementability addresses the technical and administrative feasibility of a remedy
from design through construction and operation. Factors such as availability of
services and materials, administrative feasibifity, and coordination with other
governmental agencies are considered.
Implementability at this site is a function of the complexity of the remedy.
Alternative 1, the no action alternative is most implementable because no one has
to do anything extra. Well owners would have to protect themselves. Alternatives
2 and 3 requires the cooperation of the State Engineer and the local governments
inrestdcting the use of the ground water and/or restricting land use. Alternatives
4, 5, and 6 in addition to the above cooperation,also require cooperation of the
State Engineer to give permission to pump at rates effective to contain the
contamination even though water levels throughout the area might drop thus
affecting other water fights owners. A cooperative municipal water purveyor
-would also be needed to accept the treated water which is also a requirement of
the NRD settlement. Alternative6, in addition to all the cooperation required
75
7.
°
above would also require large volumes of lime and prokiuee large volumes of
residual wastes. Traffic problems and wear and tear on roads could be the result.
Cost
The types of costs that are assessed include capital costs, annual operation and
maintenance costs and net present value of capital and O+M costs.
Alternatives 1, 2, ~md 3 are the least cosily, with costs ranging from $26M to
$45M, but none of these do anything to cleanup the aquifer. The active
remediation remedies, Alternatives 4, 5, and 6 are more costly ($197M to $360M)
but will eventually clean up the aquifer. Alternatives 4 and 5 take advantage of
existing mining "tm¢rastrueture resulting in savings in disposal costs of treatment
residues pre-mine closure. Alternative 6 is the most expensive but does not have
any apparent advantages over Alternative 5. Note that since the RI/FS was
completed, the total costs for Alternative 5 have been reduced.
State acceptance
This includes the state’s position and key concerns related to the alternatives and
comments onARARs and proposed use of waivers.
In 1995, the state and Kennecott negotiated a Consent Decree to settle a Natural
Resources Damage Claim for damages to the ground water in the Southwest
Jordan Valley. The terms of the Consent Decree established a cash payment and a
letter of credit based on the estimated cost to contain, remove, and treat the
contaminated ground water from the plume (Zones A and B). Kennecott Could
apply for a rebate against the letter of credit by extracting.the contaminated water,
treating it to drinking water quality standards and providing it to a purveyor of
municipal water for use in the affected area. In December, 1999, Kennecott
submitted to the State Trustee a plan for use of the Natural Resources Damage
settlement dollars. The plan is a combination of Alternative 5, as defined in this
ROD, and an additional treatment of sulfate contaminated ground waters
doWngradient of the Zone A acid plume. Therefore, the state supports Alternative
5, because this alternative is most consistent with the requirements of the NRD
action. The state opposes Alternatives 1, 2, and 3 because they essentially
sacrifice the aquifer’s future use forever. In a semi-arid climate, sacrificing any
future water resource has economic development impacts and presents a
continuing threat which will have to be managed in perpetuity. Alternative 4 takes
longer than Alternative 5, active cleanup of the Zone A acid plume does not take
place in the beginning,, the potential for this plume not to be captured by the barrier
wells is too risky, and costs more. Alternative 6 costs more than Alternative 5
without any apparent benefit to the aquifer or the citizens of Utah.
76
.
Community Acceptance
This determines which components of the alternatives the community support,
have concerns about, or oppose.
The primary vehicle of community participation was the Technical Review
Committee composed of technical staff from the local governments in addition to
state and federal experts. In these discussions, the Committee favored Alternative
5 over Alternative 4 because pumping of the acid plume was slated to begin fight
away and the core waters would be removed before they could migrate to the
downgradient barrier wells. They also favored use of the mining infrastructure as a
way to minimize waste handling problems. They liked the concept of attempting
to remove most of the acid plume before mine closure. Alternative 6was not
discussed much because it was more Cosily without any apparent benefit.
Alternatives 1, 2, and 3 were unacceptable to the committee because those
alternatives sacrificed any use of the aquifer for generations to come.
Alternative 5 in conjunction with a companion NRD settlement plan was supported
by the city councils in West Jordan, South Jordan, Herriman, and Riverton. There
was some disagreement on the portion of the NRD settlement plan dealing with
which cities were to receive the treated water to the four communities in the
affected area. All of the cities wanted more water than the proposal allotted, and a
few of the private well owners wanted direct supply of the water at wholesale
rates.
During the official public comment period and public hearing, very few citizens
commented on the relative merits of the alternatives. Instead, most of the
comments were on the potential consequences of the implementation of EPA’s and
UDEQ’s preferred remedy. Alternative 5 would result in,drawdowns significant
enough to influence a wide area in the western part of the valley. This means that
water levels in existing wells could drop tothe extent that they would be rendered
useless, even if the waters in that well were unaffected by the plume. Few opposed
the plan because of this, suggesting instead that a plan to deal with these water
level impacts on well owners be formulated as a part of the remedial strategy.
77
20 Summary Table of Alternatives
Criteria Alternative 1 Altcnm~ve 2 Alternative 3 Point Al~-m~e 5
No so,inn In.~tutlonal OfU~ M~Hydraulio A~ive Pumping Active Pumping -
Controls Containment lime Ueatmefit
Would not Would protect ¯Would protect Would prutect Would protect Would protect
~Reria-protec/human human health,human health, but human health and human health and human health and
prot~ion ~health or the bm pote~ialIy potenthny not the the environment the enviroummt the environment
human health environment notthc environment.
and/he environment
e~rvitonment
¯ Thre~ld Would not Would not meet Would not meet Would achieve Would achieve Would achieve
c6teria, meet meet Utah Utah U~h groundwater ARARs, but might ARA~ but ARAR~ but
ARA~groundwater groundwater cle~up ~dards in take 50 -I 50 yeats might take rmght take
cleanup ,cleanup reasonable time ¯or longer greater than 50-greater than 50-
standards in a standards in a frame ($00~ y~),150 years, but 150 yea~ same
reasonable .reasonable time s~’ne as AR 1 ~orter than Air as AR 5, ~orter
time flame frame (800+4.1hart Alt 4.
(soo + y~)yn), same as
AItL
Long term Is not effective Relies heavily Relie~ heavily on While relying . ]While relying on S~eas5
effectiveness at all. - Relies ¯ on instit~onal inaiaainnal o~ols heavily on institutional
and antlfc]y on controls for for long term instlmfional ~ls controls for long
p~n~an~e -natural Ioug/erm,for long termI aaem~on I protectivenes~term protean,
prete~tiveness,e~enfially in protection, the the plume does
.~a~yin perpetu~y andplume does not not move into
perpetuity, and natural aRenuatinn move into new areas new areas and is
natural deaned up in 50-
attenuation
and eventually
shrinks. Concem 150 yrs. Acid
~hat acld plume plume never
n~ght ~et bythe reaches banier.
banler.
Reduction of no tteatmmt,no tamlnmat, no ilo ~lgl~ il£t ueaanent reAtoes ~mnent red~Sameas5
~v ~gh no reduc~on reduction of redu~on of TMV,toxldty, mob’dity,tox~y, mobility
treatment of TMV,TMV, volume ,volume actually and volume and volume Over
volume in~a~ ~ plume a shoe~me
actuary move~frame
incrcas~ as plume moves
p]unle nlove~
Short term no action, no .no acticag no no mion, no no serious problems no serious Same as 5
"effectiveness problems (but pr~1~ (but problems (b~t no during oonstraotiou problem~ during
no progress no progr-,~s progress)-pump~ nt~ and onsm~ou-
elthec)either)well distances need pumping rates
to be detmnined ~o aadwell
ensure e~eetiveness distances need~o
be determined to
enmnw~effectiveness
78
Criteria
Cost
State
acceptan~
Community
a~’ptance
No action
no actlo~z, no
problems (but
no protection
and 13o
pro~ess)
Low
uaaccep~tabl©
unacceptable
Altemative 2
Institution~l
Controls
.o c.~,.=ing
action but
roquircs the -
cooperation of
-. thc.St~
"Unglneer and ¯
local
goven~cnts to
oontrol well use
Low
unacceptable
Alternativc3 Point
,)fUse Mgt
no action, no
problems wi~
implementatio=
Does requlre aid of
state ~, and
local water sul~Iiefs
Low
Hydraulic
Containment
technology
avaHable, few
problems
meountered
unaooeptable
unacceptable
un~le
siow~c l~h~a other
active remediadon
plaa~ m~efore
unacceptable
no conmlent
Altemative 5
Active Pumping
technology
available. ~ "
problems
encountered
High, bu~ i5%
less than
Alternative 4
conununities
s, ppod this plan.
cOupl~ with
oomt~,ioa NRD
plan
Alternative 6
Active l~.mping.
llmetreatment
technology
available, few
problems
~,~mt~
except disposal of
sludges produced
by lime acaanent
would require
lots of land (and
llme supplies
could get scarce).
Very High
waste disposal
problems "
no ootrmlent
79
K. - Principal Threat Waste:
The principal threat waste is the source of the acid plume containing high metal and sulfate
concentrations. In this case, the sources of the acid plume have been addressed in previous
actions. However, the acid plume itself is not much different in composition as the original
sources. Alfematives 1, 2, and 3 do not address the remnants of the principal threats in the
aquifer itself. Human exposure to the waste is prevented by institutional controls essentially in
perpetuity. Alternatives 4, 5, and 6 address the remnants of the principal threats in the aquifer by
pumping the acid plume from the aquifer, treating the water, and providing the water to
municipalities for beneficial use.
L.Selected Remedy
EPA and UDEQ have selected Alternative 5 as the remedy for addressing the acid plume
at Operable Unit 2 .of the Kennecott South Zone site.
1.Summary of the Rationale for the Selected Remedy
EPA and UDEQ selected Alternative 5 for the following reasons.
a.EI~A and LIDEQ preferred active remediation of the plume in Zone A. It
was unaeeeptable to allow the plume to continue to move downgradient
polluting more and more ground water as it did so. Containment was a
minimum requirement to prevent a major municipal well field from being
impacted and to prevent a potential impact on the Jordan River. The active
remediationalternatives were Alternatives 4, 5, and 6. All others were
eliminated from further consideration as not protective and failing to meet
remedial goals.
b°Of the active remediation alternatives, Alternatives 4, 5, and 6, Alternatives
5 and 6 were preferred relative to Alternative 4 because withdrawals of the
acid plume were slated to begin right away, 10 years ahead of Alternative
4. This would mean that the aquifer has the potential to be remediated
faster in Alternatives 5 and 6. Pilot testing would be required for
Alternatives 4, 5, and 6 to prove operation status and sustainability.
Alternative 4 also relies on a single barrier well system to contain the
plume. The consequences of the acid plume escaping capture of the barrier
wells and migrating farther could be extreme.
C°Of the fastest active remediation alternatives, Alternatives 5 and 6,
Alternative 5 was preferred because its costs were less with the same
benefits to the aquifer. Alternative 5 hadthe added benefit ofusing
existing waste handling inflastructure of the mining company so long as the
80
.
mining operations continued. The waste handling problems associated with
Alternative_6, although traditional, would have implementability problems
requiring transportation of large quantities of lime and treatment sludges.
Finally, Alternative 5 fits best with a plan to .settle the NRD issues at the
site. Similar treatment technologies are proposed for use in both the
CERCLA and NRD plans and thesystems can be integrated at key spots.
Description of the selected remedy
Operations and maintenance of surface source controls (already implemented
under provisions of a state Ground Water Protection Permit).
Integration and use of Institutional Controls, upon approval by the State Engineer
while restoration is ongoing:
Institutional controls include, but are not limited to, well drilling
moratorium by the Utah State Engineer, pumping limits placed on existing
wells by the Utah State Engineer, purchase (or exchange) of land, purchase
(or exchange) of water fights, municipal zoning and land Use regulations.
Other options are available to the State Engineer. The State Engineer
reviews impacts to the water fights owners and public comments.
Point of Use Management for private well owners while restoration is ongoing:
Point of Use Management includes, but is not limited to, providing
replacement water to private well owners by hooking them up to municipal
culinary systems, the provision of in-home treatment units (e. g., reverse
osmosis units) when the household is beyond the municipal service area,
the provision of bottled water, extension of wells into uncontaminated
portions of the aquifer, replacement of wells.
Development of a plan to deal with consequences of water level drops caused by
pumping of the acid plume:
The agencies will request that, as a part of RD/RA, the PRP devise a
method to mitigate the impact of drawdowns on private and municipal
wells located in and near the affected area. This plan could include the
following actions, performed on a case-by-ease basis: Drilling of new and
deeper wells, installing well completions at deeper depths, alternate water
sources, purchase or exchange of water fights, well abandonment and
compensation.
Installation of a barrier well containment system at the leading edge of the acid
plume (where sulfate concentrations are less than 1500 ppm in the projected
migration pathway of the plume movement)
The performance standard for this system requires that no waters
81
exceeding state and federal drinking water standards for metals or
exceeding 1500 ppm sulfate shall migrate 0ffKennecott property (as of
December 13, 2000) past the barrier wells.
Installation of a well or wells in the core of the acid plum~: (There are already two
wells which have been installed in core area for pilot testing purposes.)
Pretreatment of acid water using nanofiltration.
Treatment of pretreated acid waters by a reverse osmosis plant,
Treatment of the waters from the barrier wells by a reverse osmosis plant.
Treated water is delivered to a municipal water purveyor (asrequired for a rebate
as stated in the Natural Resources Damage Settlement plan and approved by the
State Trustee).
Installation and maintenance of a monitoring system to track the movement of the
plume, the progress of active remediation, and measure the progress of natural
attenuation for the sulfate contamination within the Zone A plume and
downgradient of the barrier wells. The goal of the natural attenuation is to achieve
the State’s primary drinking water standard ofS00 ppm
Prior to mine closure, the concentrates from NF plant and RO plant are disposed in
Kennecott’s railings pipeline, The railings pipeline serves as a 13 mile linear
treatment system. Acids would be neutralized and metals would precipitate into
the tailings slurry. Metals are stored along with tailings in the Magna Tailings
Impoundment, newly expanded and renovated.
Following cessation of nearby mining and milling operations, the NF and RO
concentrates shall be disposed in a facility appropriate to the types of wastes then
remaining in the concentrate. None of the spee’tfic requirements mentioned in the
description &alternatives will be chosen at this time. A disposal method which
could be implemented quickly following mine closure must be included as a part of
RD/RA. In 30 years, it is anticipated that other technologies maybe available to
handle residuals from the treatment plants. Closure of the mine may require
infrastructure and O+M which could be used also for the concentrates, the
chemistry of the ground water could be significantly less concentrated than today,
and more will be known about the nature of any proposed discharge to the Great
Salt Lake and the potential effects thereof. The Agencies also acknowledge the
possibility of a completely different option for addressing the concentrates upon
mine closure. EPA and UDEQ would then encourage the submittal of a new
82
proposal that takes into consideration changed circumstances and new technology
to more effectively address the concentrates.
Should the plume begin to impact the West Iordan Municipal Well Held (either
through increased loadings or water level drops), a reinjection program may be
considered.
3.Summary of the Estimated Remedy Costs
The information in this cost estimate summarytable is based on the best available
information regarding the anticipated scope of the remedial action. Changes in the
cost elements are likely to occur as a result of new information and data collected
during the engineering and design of the remedy, Major changes may be
documented in the form of a memorandum in the Administrative Record file, an
Explanation of Significant Differences, or a Record of Decision Amendment. This
is an order-of-magnitude engineering cost estimate that is expected to be within
+50°,4 to -30% of the actual project cost. Since the RI/FS was submitted, there
have¯ been additional cost estimates which are lower than those presented here.
This version is verbatim from the R//FS.
ACTIVITY
Source controls
F Institutional Controls
PROJECT COST ESTIMATE
CAPITAL COSTS
(From Appendix M, RI/FS Report,
Quantity Unit "
Water rights and land use restrictions
Point of use management
Municipal Connections
Household Treatment Units
Draw down impacts (potential)
Private well owners
I lot
35,000 Linear fl:
|, ,’
[998@), ..
Unit Cost
$I6,000,000
TotalCost
4
$25
ah’eady
constructed.
$16,000,000
$875,000
400 $1,500 $600,000
25 wells with
20-40 ft drops,
15 wells with
40-100 ft drops,
4 wells with
>100 ft drops
case by case
basis
not estimated
83
ACTIVITY Quantity Unit Unit Cost Total. Cost
Municipal wefts 2 wells with 20-case by case not estimated
40 ft drops,4 basis
wells with >I00
i~ drops "
Reinjection program unknown c~ebyc~e
basis t
not estimated
l
Barrier Well extraction and RO
treatment
Wells (C’ steel)10,000 Linear 11 $260 $2,600,000
Well Pump Stations 6 $425,000 $2,550,000
Booster Pump Stations 1 $550,OOO ¯$ 550,000
Power substations 3 $150,000 $ 450,000
Reverse Osmosis Facility 2,000 gpm $3.20/gal per $9,216,000
day
6" - i2" diet. C’ steel pipelines 20,000 Linear fl $85 $1,700,000
8" concentrate C’ steel pipeline 500 Linear ft $70 $ 35,000
Power transmission lines 2o, ooo Linear ft $45 $ 900,000
Acid plume (core waters) extraction to
Nanofiltration pretreatment and Reverse
Osmosis Treatment
Wells (stainless steel)5000 Linear tt $35O $1,750,000 ~
¯ ,,,,"i’
Well Pump Station 5 $5oo, ooo $2,500,000
Booster Pump Station .$600,000 $ 600;000 .
Power substations - ’t2 ¯’$150,000 $ 300,000
, l,
6" - 12" dia pipelines (stainless steel)10,000 Linear ft $140 .$1,400,000
Power transmission lines 10,000 L’mear ft $45 $ 450,000
Nanofiltration facility 1,500 gpm (this $4.10/gal.day $ 8,856,000
flow depends on
remedial design)
84
ACTIVITY - -
Modify Reverse Osmosis Plant above
to increase the flow to 2;750 gpm
Upgrade existing lime treatrnent plant
at concentrator and head oftailings line
(750 gpm) "
New disposal infrastructure for use
following mine closure
Sub Total
EPCM
Contingency "
Quantity Unit
1 lot ,
1 lot
20% construct,
1% IC, POU
25% construct,
2% IC, Pou
TOTAL
03 costs were.estimated in 1998 and were not adjusted.for inflation
. ,.,’.~,
Unit Cost Total Cost
$2,000,000 $2,000,000
$3,000,000 $3,000,000
not estimated
$56,302,000
$ 8,106,000
$12,327,000
$76,735,000
ESTIMATED ANNUAL PROJECT COSTS
OPERATIONS AND MAINTENANCE
(From Appendix M_, R//FS Report, 1998)
:Activity
Monitoring
Personnel and equipment
Analytical services
Annual report preparation
Source Control Operations and
Maintenance
.Quantity unit
2 technicians ¯
700 analyses
" )
1 lot
1% of
construction cost
Unit Cost
$50,00O
$500
$20,000
$127,000,000
Institutional Controls none none
Point of Use Management
Maintenance of household Re units 10% of capital $600,000
,coSt
total
$100,000
$350,000
|
$20,000
.$!,270,000
none
$60,000
85
Activity Quantity unit Unit Cost total
Barrier Well extraction plus RO
treatment
Power for pumping 3,609,000 kWh $0.035 $126,000
Maintenance .5% of $18,001,000 $900,000
construction cost
=, ,
RO System 2000 gpm $0.84 $883,000
(product flow
rate)
Operations Labor 5 persons $50,000 ’ f $25o,ooo
Acid extraction to Nanofiltration and ¯ ¯ "j
RO treatment
Power for pumping 3,003,000kWh $o.o35 $105,000
J
Maintenance 5% of $20,856,000 ¯$1,043,000
construction cost
Operations Labor 5 persons s5o,ooo $250,000
NF system 1,500 gpm $1.26 $993,000
(product flow
rate, depends on
design)
,==
Lime 750 gpm at O. 1 r$75 $1,478,000
lb per gal =
19,710 tons
Subtotal " ". -$7,828,000
EPCM 1% Source $ 318,600
Cont, POU, 5%
treatment-,
Contingency 5% Source $1,673,000
Cont, POU, 25%
treatment
TOTAL $9,819,600
86
SUMMARY OF TOTAL COSTS
CAPITAL AND NET PRESENT VALUE
(From Appendix M, RI/FS)
A~ivity
Capital - Institutional Controls
r Capital - Point of Use Management
Capital - Wells and Treatment
O+M Source Control @ 1,844,000Iyr
O+M Institutional Controls
O+M Point of Use @64,000/yr
O+M Wells and Treatment
Sulfate extraction and RO
Acid extraction, NF, RO
TOTAL NET PRESENT VALUE
Assumptions
7% discount
7% discount
7% discount
7% discount
none
7% discount
7% discount
7% discount
Years
2 ¯t
2
J,
1,s44,0O0/yr
for perpetuity
64,000/yr for
perpetuity
2,826,000/yr
for perpetuity
5,079,000/yr
for 21 years
total
16,049,000
17,528,000
40,715,000
26,343,000
914,000
40,372,000
$55,031,000
$197M
4.Expected Outcomes of the Selected Remedy:
Theoverall objective of the selected remedy in conjunction with the N1LD
settlement action is to remediate the aquifer so that full unrestricted use of
the ground water by public and municipal well owners is achieved.
Because this will taken long time, perhaps 50 - 150 years or longer, it is
also necessary to contain the plume from further migration so that the
situation does not become worse and private well owners are not exposed
to unacceptable concentrations of contaminants. Containment will also
prevent contamination of the Jordan River and exposure of aquatic
organisms to the plume contaminants. Until the aquifer meets drinking
water standards, water treated as a part of this program can be used by the
public.
The final cleanup levels for the remedy are given in the following table:
FINAL CLEANUP LEVELS FOR THE SELECTED REMEDY
87
Contan~ant Remediation Level Containment Level at Treatment Level for
throughout acid Kennecott property RO treatment plant
plume line downgradient of
Zone’A (as of 12-13-,
2000)]
Basis health based levels health based levels ARAR, state primary
from site specific risk from site specific risk and secondary
r assessment assessment drinking water
standards.
acidity pH = 6.5 - 8.5 pH=6.5-8.5 pH = 6.5 - 8.5
Arsenic 0.05 mg/l 0.05 rag/1 .. t 0.05 mg/l
Barium 2mg/l ¯2mg/1 2mg/l
Cadmium 0.005 mg/l 0.005 toga 0.005 mg/l
Copper 1.3 mg/l 1..3 mg/1..1.0 mg/1
Fluoride ,4mg/l 2mg/l ¯ ,. ,
Lead.0.015 mg/l 0.015 mg/1 0.015 mg/l
Nitrate 10 mg/l 10 mg/1 ...10 rag/1
Selenium 0.05 mg/l 0.05 mg/l 0.05 mg/l
Nickel 0.1 mg/l 0.1 mg/l 0.I mg/I
Aluminum 0.05 - 2mg/l
Chloride 250 mg/1
Manganese 0.05 mg/1
Silver 0.10 mgfll
Sulfate 1500 rag/l, active 1500 mg/l 250mgh
CERCLA
remediation
500 rag/l, passive
CERCLA action via
natural attenuation
88
Contaminant Remediation Level
throughout acid
~lume
Treatment Level for
RO treatment plant
Corrtainment Level at
Kennecott property.
line downgradient of
Zone A (as of 12-13-
2ooo)
TDS -500 mg/l
Zinc
89
M. Statutory Determinations
The following describes how the selected remedy will satisfy the statutory requirement of
the nine selection criteria specified in the National Contingency Plan
.
Protection of Human Health and the Environment: Human health is protected by
the selected remedy both short term and long term. Short term protection is
achieved by limiting exposure of residents to contaminated ground water through
use of institutional controls, point-of-use management and bycontainment of the
plume from further migration. Environmental protection is achieved by
containment of the plume such that the contaminants do not reach the exposure
point at the Jordan River. Long term protection of both human health and the
environment is achieved by active remediafion of the plume so that the waters can
be returned to beneficial use without restrictions.
.
Compliance with Applicable or Relevant and Appropriate Requirements (ARARs.):
Section 121(d) of CERCLA, 42 U.S.C. § 9621(d), the National Oil and Hazardous
Substances Pollution Contingency Plan (the ’~xlCP"), 40 CFR Part 300 (1990), and
guidance and policy issued by EPA require that remedial actions under CEKCLA
comply with substantive provisions of appli~ble or relevant and appropriate
standards, requirements, criteria, or limitations ("ARARs") from State of Utah and
federal environmental laws and State facility siting laws during and at the
completion of the remedial action_ These requirements are threshold standards
that any selected remedy must meet.
This document identifies ARAKs that apply to the activities to be conducted under
the Southwestern Jordan River Valley Ground Water Plumes Operable Unit 2
remedial action. The ARA~ or groups of related ARARs contained in Appendix
A are each identified by a statutory or regulatory citation, followed by a brief
explanation of the ARAK and how and to what extent the ARAR is expected to
apply to the activities to be conducted under this remedial action.
Substantive provisions of the requirements listed in Appendix A are identified as
ARARs pursuant to 40 CFR § 300.400. ARARs that are within the scope of this
remedial action must be attained during and at the completion of the remedial
action.
Types ofARARs: ARARs are either "applicable" or "relevant and appropriate."
Both types of requirements are mandatory under Superfund guidance. Applicable
requirements are those cleanup standards, standards of control, and other
Substantive requirements, criteria or limitations promulgated under federal
environmental or state environmental facility siting laws that specifically address a
hazardous substance, pollutant, contaminant, remedial action, location, or other
90
circumstance found at a CERCLA site. Only those state standards that are
identified by a state in a timely manner and that are more stringent than federal
requirements may be applicable. "
Relevant and appropriate requirements are those cleanup standards, standards of
control, and other substantive requirements, criteria or limitations promulgated
under federal environmental or state environmental or facility siting lawsthat,
while not ,applicable" to hazardous substances, pollutants, contaminants, remedial
actions, locations, or other circumstances at a CERCLA site, address problems or
situations sufficiently similar to those encountered at the CERCLA site that their
use is well suited to the particular site. Only those state standards that are
identified in a timely manner and are more stringent than federal requirements may
be relevant and appropriate.
The determination that a requirement is relevant and appropriate is a two-step
process: (1) determinationifa requirement is relevant and (2) determination if a
requirement is appropriate. In general, this involves a comparison of a number of
site-specific factors, including an examination of the purpose of the requirement
and the purpose of the proposed CERCLA action; the medium and substances
regulated by the requirement and the proposed requirement; the actions or
activities regulated by the requirement and the remedial action; and the potential
use of resources addressed in the requirement and the remedial action. When the
analysis results in a determination that a requirement is both relevant and
appropriate, such a requirement must be compiled with to. the same degree as if it
were applicable.
ARARs are contaminant, location, or action specific. Contaminant specific
requirements address chemical or physical characteristics of compounds or
substances on Sites. These values establish acceptable amounts or concentrations
of chemicals which may be found in or discharged to the ambient environment.
Location specific requirements are restrictions placed upon the concentrations of
hazardous substances or the conduct of cleanup activitiesbecause they are in
specific locations. Location specific ARARs relate to the geographical or physical
positions of sites, rather than to the nature of contaminants at sites.
Action specific requirements are usually technology based or activity based
requirements or limitations on actions taken with respect to hazardous substances,
pollutants or contaminants. A given cleanup activity will trigger an action specific
requirement. Such requirements do not themselves determine the cleanup alterna-
tive, but define how chosen cleanup methods should be performed.
Many requirements listed as ARARs are promulgated as identical or near identical
requirements in both federal and state law, usually pursuant to delegated
environmental programs administered by EPA and the state. The Preamble to the
91
.
Q
NCP provides that such a situation results in citation to the state provision and
treatment of the provision as a federal requirement.
Also cont~fined in this list are policies, guidance or other sources of information
which are "to be considered" in the selection of the remedy and implementation of
the ROD. Although not enforceable requirements, these documents are important
sources of information which EPA and the UDEQ may consider during selection
of the remedy, especially in regard to the evaluation of public health and
environmental risks; or which will be referred to, as appropriate, in selecting and
developing cleanup aetions~
This list in Appendix A constitutes EPA’s and UDEQ’s formal identification and
detailed description of ARARs for the remedial action at the Kennecott South
Zone Site, Southwestern Jordan River Valley Ground Water Plumes Operable Unit
2.
Cost Effectiveness: A Cost Effective remedy in the Superfund program is one
whose costs are proportional to its overall effectiveness. This includes long term
and short term effectiveness and reduction of toxicity, mobility, and volume
through treatment.
At this site, the remedial alternatives fall into two groups:
(1) Alternatives 1, 2, and 3 contain no active remediation.component, but rely on
personal controls, institutional controls or replacement waters to prevent exposure
to the citizemy. The plume continues to move downgradient until it discharges to
the Iordan River contaminating more and more of the aquifer as it moves. These
alternatives are relatively low in cost, but do not protect the environment long
term. In addition, the ground waters are not returned to beneficial use.
(2) Alternatives 4, 5, and 6 contain an active remediation component and achieve
containment of the plume and eventual remediation of the aquifer. In addition,
Alternative 4 might not be effective in containing ithe plume in long term.
Although Alternative 4 could be slower than the Alternatives 5 and 6, the results
are roughly equivalent in terms of effectiveness, permanence, and reduction of
toxicity, mobility, and volume through treatment in theshort term. Alternative 5 is
the most cost effective of the active remediation alternatives. It has an added
advantage over Alternative 6 producing no sludges requiring disposal prior to mine
closure. All alternatives would have to deal with treatment residuals post mine
closure, but because Alternatives 5 and 6 would be faster, the amount of residuals
would probabl3; be less.
Utilization of Permanent solutions and altemative Treatment to the Maximum
Extent Practicable: Alternative 5 takes advantage of an emerging technology using
membrane technology., such as nanofiltration. Since it achieved the same goals as
92
°
the more traditional treatment technologies at a lower cost, it was sdectcd. The
sdected remedy fulfills the requirement for use of innovative technologies to the
maximum extent practicable. It also provides a permanent solution to the ground
water problem although this could take 50 years or longer.
Preference for Treatment as a Principal Element: The selected remedy uses
treatment as a principal dement in remediation of the aquifer and meets the
statutory requirement. Monitored Natural Attenuation (MNA) is used as a
supplement to the active restoration only after the contaminants in the plume have
been reduced to levels that are protective of human health and the environment.
The extended time frame for MNA is reasonable in fight of the uncertainties as to
whether additional active restoration of the remaining sulfate would decrease the
time required to meet MCLs as compared to MIqA.
.
Five-year Review Requirements: Since hazardous substance, pollutants, and
contaminants will remain on-site in the aquifer while the long-term remedial action
is on-going, five year reviews are required at this site to determine if the remedy
continues to remain effective, protect human health and the environment, and
comply with ARARs.
N.DOCUMENTATION OF SIGNIFICANT CHANGES
The Selected Remedy is essentially the same as Alternative 5 which was the preferred
alternative 0fEPA and UDEQ as presented to the public. As a result of the public comment, an
additional dement was added to Alternative 5 in the Sdected Remedy. The additional dement
was EPA’s and UDEQ’ s response to a potential problem of water level drawdowns in the aquifer
as a result of aggressive pumping from the acid plume. The change requires private or municipal
well owners who discover their wells have been rendered useless because of water level declines
as a result of this project should be consulted and provided with options to solve their problem by-
the PRP. This would be done on a case-by-ease basis. Solutions would be dependent on the
nature of the well, its uses, and the cost of alternatives. The plan will be included as a work
dement in the RD/RA Consent Decree.
93
PART 3: RESPONSIVENESS SUMMARY
A public comment period was held on the joint Natural Resources Damage Settlement
Plan (administered under a ConsentDecree entered in Federal Court by the State of Utah,
Kennecott Utah Copper Corporation and the Jordan Valley Water Conservancy District) and the
Proposed Plan for the CERCLA action. The Public Meeting also covered both plans. This
Responsiveness Summary (an attachment to the EPA Record of Decision) deals solely with those
issues and concerns raised by the interested parties concerning only the CERCLA portion of the
action. The comments regarding the Natural Resources Damage Settlement Plan will be
submitted separately to the Utah Natural Resources Trustee.
Please note that some of the comments have been edited. The full version of the
comments is available in the Administrative Record.
E-mail from Glenn and Melody Rowe
2427 Temple View Lane
South Jordan, UT 87095
1.Comment: We agree with the need to dean up the plume.
Answer: EPA and UDEQ concur with this comment. If the plume is not cleaned up,
contaminated ground water will continue to move downgradient toward the Jordan River
continuing to contaminate additional areas. More wellswill be impacted and the aquatic
life in the JordanRiver might also affected by the additional load of contaminatiorL
.
Comment: We wonder what other hazards are there about which we are not be’rag
given complete information.
Answer: EPA and UDEQ in conjunction Kennecott established a systematic approach to
identifying and correcting all the significant environmental problems produced by mining
activities in the Oquirrh Mountains since the 1860s. Kennecott agreed to evaluate
historic sites on their property and UDEQ took the lead in investigating potential off-site
problems. During UDEQ ’s investigations, every watershed coming down the east side of
the Oquirrhs was studied and areas of airborne deposition were evaluated as well. A few
additional problems were found and the agencies launched a cleanup program for those.
Kennecott has nearly completed their investigations of historic (and current) facilities.
The list of sites was compiled from books and articles written during various time
periods, interviews with former employees, historic photographs, diaries, and newstmper
accounts. Each site was located, and sampled for wastes remaining on the property. If
the wastes couM wash downstream, or if the wastes could leach materials to the ground
water, the wastes were removed and placed into repositories. Several pockets of
contamination were found and cleaned up in this project. EPA and UDEQ are now
confident that we are unlikely to find any further surprises due to mining activities in the
94
Oquirrhs. If, however, additional contamination is discovered in the future, EPA and
UDEQ still have the authority to address it appropriately. The information gathered
during this project is available for public viewing at the offices of UDEQ, 168 N 1950 W,
Salt Lake City.
.
Comment: We also wonder about the comment that the water does not damage
plants. Some Shade trees watered with our well water have died.
Answer: Thank you for the information. EPA and UDJZQ were also concerned about the
impact of elevated sulfates on irrigation water because many of the water wells in this
area are used for irrigatiort Two studies concerning use of these waters for irrigation
were conducted. The first study was conducted by Utah State University in which
examples of different classes of plants were grown in a greenhouse and irrigated with
waters from the Kennecott site. They found that increasing amounts of sulfate up to 1700
ppm sulfate did not impact fescue, alfalfa, or broccoli. The highest sulfate level did
reduce bean growth but bean yield was unimpacted. This study was conducted through
one growing season.
Kennecott conctueted a follow up outdoors study on the former footprint of the South
Jordan Evaporation Ponds. They used different watersto irrigate different plants
commonly found in a suburban se~’ng. Plants included sod, shrubs, perennial and
annual flowers, vegetables such as tomatoes and corn, and a few trees. This study was
conducted over a three year period- Waters tested included4 different waters from
different wells and tunnels plus water from South Jordan culinary system. In response to
this concern, Kennecott investigators have gone back to the original field notes and data
regarding the trees in their study. Kennecott’s experiment included shrubs, conifers, arid
fruit trees. No shade trees were included. There were a few trees that did not survive the
first winter. This was attributed to normal la’lls associatedwith use of nursery stocl~
According to Kennecott, the well in question was identified by Kennecott in the well
inventory study as SJG1684. Water quality sampling revealed that the sulfate
concentration in 1994 was 450 mg/Z and the chloride concentration was 237 mg/L. The
water also had 114 mg/Z sodium, a constituent to which many plants are sensitive. The
chloride and sodium concentrations are high relative to contamination attributable to
Kennecott, but at least a portion of the sulfate is attributable to Kennecott. The health of
the trees may not have been due to the increased sulfate from Kennecott sources, but
rather due to the elevated chloride and sodium present in the water.
II Letter from Mike R. Barela
13320 S 7565 W
Herriman, UT 84065
95
°Comment: Real estate values will drop if homes in the affected area are not
provided an alternative source of water.
Answer: Adequate drinking water supplies are a vital element in planningfor
development in growing communities. Retrofitting gets complicated especially when
competing interests are involved Customers get caught in the middle. When the
situation is caused by contamination from nearby industrial sources, EPA and UDEQ
have authority to act. Otherwise, this is a local problem.
,
Comment: If water is provided for one area it should be provided to all areas
affected. Funds set aside by Kenneeottshould be used to (restore, replace, or
acquire the equivalent) to both zones A and B.
Answer: Funding to provide alternative water was apart of the NRD settlement. The
CERCLA action is not primarily concerned with the provision of treated water to the
public within the affected arecL The decision on allocation of any treated water is up to
the State Trustee. Under the current proposal to the Trustee submitted by JVWCD and
Kennecott, division of the water is based on the area of affected ground water within the
boundaries of each system, the population served, and the water rights held by each
entity.
°Comment: What is being done to protect the citizens in Herriman from
contaminated water?
Answer: Under provisions of a State of Utah Ground Water Protection Permit, Kennecott
was required to install a leachate collection system to trap any waters coming from their
dumps; This shouldprevent contamination in the future.
,
Comment: How do we make sure that new drilling or increased pumping for water
supplies Which go to other areas does not affect wells in Hexdman7
Answer: The ground water model developed by USGS and Kennecott suggests that
pumping of the acid waters from the plume associated with Bingham Canyon will drop
water levels as far away as 11errimarL EPA, UDEQ~ Kennecott and JVWCD all agree
that the model is simply a prediction tool that is only as good as our current lmowledge
of the groundwater in the arecL For this reason, all advocate a continuing monitoring
program which will study’both the water levels in the wells of this area and the water
quality of those wells. This information can be used to refine the calculations and model
and give an early warning if water levels are affected due to pumping in this project.
Corrective action may be necessary either to replace water or deepen the impacted wells
shouM this occur.
96
Comment: If wells in Herriman are affected, when would replacement water
become available?
Answer: lf water levels begin to drop because of pumping of the acid p!ume, it will be a
gradual decline and sufficient time will be available for planning and construction of the
needed infrastructure.
.
Comment: Would wells in Herriman be monitored for contamination on a regular
basis?
Answer: Continued monitoring of the welIs in the affected areas will be apart of this
project. The monitoring program can be used to determine if the groundwater levels are
being influenced by the withdrawal of the acid plume and check to see if ground water
quality is improving or degrading as a result of this effort. Also public water supplies
are monitored on a regular basis as required by the State Drinking Water Program.
10.Comment: What are the long term health effects for this type of contamination?
Answer: The health impacts of sulfates in drinking water are largely acute rather than
chronic. Sulfates in h~gh Concentrations cause diarrhea. It is even used in over the
counter laxative medicines. The impacts are short lived and there is evidence that people
get acclimated to elevated sulfates in their water within a week and the effects disappear.
Even these short term impacts can have serious consequences for infants where the
diarrhea can cause rapid dehydra~on. The only long term impact even theoretically
linked to sulfates in drinking water is formation of kidney stones. Kidney stones are
thought to be related to calcium content of the urine and some investigators have linked
sulfate ingestion with calcium in the urine, hence the theory that sulfate may be involved.
This is disputed by other investigators who found no relationship between sulfate
ingestion and kidney stone formation.
Letter ~omHerrimanResiden~forResponsibleRedamation
RichardDansie, Prefident
6120W. 13100 S.
Herriman, UT84065
11.Comment: The members of HRRR are concerned about the drawdown and the
impact on surrounding municipal and privately held wells and water resources.
Answer: Drawdowns may occur associated with accelerated pumping of the acid plume.
A provision in the selected remedy was added to deal with this potentialproblem.
12.Comment: Should substantial losses occur due to drawdown of the water table; the
plan should include options to be implemented. These could include restoration,
97
IV
replacement or acquisition of waters for municipalities and private well owners.
The replacement options should be identified now, and the drawdown should be
monitored.
Answer: The computer model predicts that there will be drawdown from the acid plume
remediation. As the pumping is occurring, wells in the Herriman area will be monitored
for water level and quality. If the monitoring program reveals evidence of drawdown in
the Herriman area attributable to acid plume remediation, several options are available
to compensate the water users in Herriman. These include: (1) hook up to municipal
water, paid for by Kennecott; (2) installation and maintenance of a residential reverse
osmosis treatment system if municipal water hook-up is impractical; (3) deepening of the
affected well if it is thought that a deeper well wouM yield sufficient replacement water;
(4) replacement of water using Kennecott sources, or (5) underground injection
upgradient of affected wells to counterbalance the drawdown. A provision in the selected
remedy was added to deal with this potential problem.
Letter from Marcelle Shoop
Kennecott Utah Copper Corporation
P.O. Box 6001
Magna, UT 84044
13.Comment: Kennecott requests that the ROD include a brief explanation in a
footnote or parenthetical clarifying the use of the name "Kennecott". The
company now known as Kennecott Utah Copper Corporation has operated in the
past under several names and has been owned by different holding companies.
Other companies with Kennecott in the title are not involved with Bingham
Canyon operations.
Answer: EPA is not opposed to including a clarification concerning the name
"Kennecott’" when referring to historic entities conducting activities relative to the site.
A chronology of companies using the name "’Kennecott" wasprovidedby Kennecott
Utah Copper Corporation and is included in the administrative record for this action.
14.Comment: Kennecott requests that Zone B treatment facilities not be a part of the
ROD, but rather solely part of the NRD settlement. Zone A should only be
addressed by the ROD. CEKCLA authority in Zone A is clear and uncontested;
whereas, CERCLA authority in Zone B is controversial. The use of the NRD
settlement for Zone B takes care of this situation.
Answer: While EPA remains concerned about both the Zone A and ZoneB plumes, it
believes that the combination of CERCLA and State Natural Resources Damages
Consent Decree authorities adequately ensures that both plumes will be addressed
EPA ’s ROD will address only the Zone A plume, with the expressed expectation that the
98
V
VI
State’s Consent Decree will address the Zone B plume. EPA does not necessarily agree
with Kennecott’s interpretation of whether CERCLA can reach the Zone B plume, and
reserves its rights to assert contrary arguments or to address the Zone B plume at a later
date, if warranted
Letter and Fax from Roger Payne,
City of West Jordan
803 0 S 4000 W
West Jordan, UT 84088
15.Comment: The City of West Jordan understands the need to clean up this valuable
resource, and to correct the problems with the ground water supply.
Answer: Thank you for your support. The City has been an active participant in the
Technical Review Committee for the project, both in expressing concerns throughout the
study phase and in evaluating the various alternatives.
16.Comment: The City suggests delivery of the Zone A water to a proposed city
reservoir at elevation 5335 feet rather than the District’s existing reservoir at
elevation 5148 feet. This would allow the city to service growing western suburbs
without pumping.
Answer: JVWCD has indicated to EPA that it has metwith West Jordan City to discuss
this proposal to co-locate a pump station at the Zone .4 plant for delivering the City’s
allocation of Zone A treated water to a slighly higher elevation. JVWCD will cooperate
with the City to accomplish this objective.
17.Comment: The City is concerned about maintaining the existing municipal well
field located just north of the current boundary of the contaminated plume. The
City would like to investigate additional measures to protect this well field such as
a ground water recharge program.
Answer: EPA and UDEQ are also concerned about protecting this well field We have
included in the selected remedy an option to include reinjection of water as an additional
protective measure should this become necessary in the future. Appropriate ground
water modeling would need to be performed and permits wouM need to be obtained. The
alternative to store water in the winter months in above-ground tanks instead of injection
may also be considered.
Letter from Dansie Water Company,
Rodney, Richard, and Boyd Dansie
7198 West 13090 South
Herriman, UT 84065
99
18.Comment: The water in Dansie culinary wells has been degraded by Kennecott
operations.
Answer: Unlike the contaminated groundwater plumes down gradient of the Bingham
Canyon operations and the Lark mines where the mining related sources are clear and
obvious, the sources of the high TDS in the ground water in the ButterfieM Creek area
are not as certain. This is because the ground water in the ButterfieM Creek area is also
characterized by elevated chlorides in addition to sulfates. Waters from Kennecott’s
leaching operations are characterized by elevated sulfates but are rather poor in
chloride. Therefore, it is possible that the high TDS of groundwater in the ButterfieM
Creek area may be influenced by other sources which may not be mining related at all. It
would take substantial studies and investigations to determine the exact causes of the
high TDS and chloride which may be caused by the leaching of soluble components from
the volcanic rock of the arec~ Contamination from Kennecott sources is only one of
several possibilities: One study suggests that the elevated chlorides come from
hydrothermal activity or brines leflfrom the formation of the ore body. In this situation,
chlorides and other components are a natural component of the ground water. For more
details on this, see discussion of Herriman wells in the Shepherd-Miller report, Appendix
B of the Remedial Investigation report.
Another way to determine if Kennecott operations are in fact responsible for
contamination is by examination of historical water quali~y information - comparison of
today’s water quality with water quality prior to Kennecott dumping. EPA does not
require industries to clean up waters cleaner than background concentrations~
CERCLA has authority to take action when there is a risk to human health (or a potential
risk to human health. Although the Dansie water may be high inTDS, there is no
evidence that any health based standard has been violated recently.
Please also note that EPA does not take a position with respect to any claims that the
Dansies, or any other party, may have with respect to Kennecott or other potentialIy
responsible parties, as defined by CERCLA, at this or other Superfund sites. The ROD
speaks to EPA "s preferred remedy for addressing the contamination at the Kennecott
South Zone site. It does not address the liability of any parties associated with the site.
19.Comment: If the Dansie property is included in the site, where does the Dansie
Water Company get its replacement water?
Answer) This question should be negotiated between the Dansie Water Company,
Kennecott, the Jordan Valley Water Conservancy District, and perhaps the town of
Herriman. The site is defined as ground water which has been affected by mining
activities. At this time, it is not certain that the Dansie wells have been affected by
mining, or that the waterfrom the Dansie wells pose a health risk above background
100
20.Comment: Dansie Water Company is concerned about the effect of draw down on
its wels and surface water supples.
Answer: The ground water model developed by USGS and Kennecott suggests that
pumping of the acid waters from the plume associated with Bingham Canyon will lower
water levels as far away as HerrimarL Surface water supply (Butterfield Creek) is not
affected in this model. The model is simply a prediction tool that is only as good as our
current knowledge of the groundwater, in the area; therefore, a continuing monitoring
program which wilt monitor water levels and water quality of the Dansie Water Company
wells and other area wells will be implemented Cooperation with private well owners is
vital to the success of this monitoring program. Monitoring information can then be
used to refine the calculations and model and give an early warning if water levels are
affected by pumping in this project and/or pumping by other parties. Corrective action
maybe necessary either to replace water or deepen the impacted wells should this occur.
Development oft plan to deal with potential drawdowns on municipal and private wells
has been included as a part of the selected remedy.
21.Comment: It would be better to use Utah Lake water rather than water from the
Bingham area plume. It would take less treatment and produce no drawdowns.
Answer: Although this suggestion would have great merit if this were strictly a water
supply project, the main goal of the project is to withdraw the acid plume and keep it
from moving downgradient polluting more of the aquifer as it travels. For CERCLA, the
use of the water following withdrawal is only a secondary concern. The NRD settlement
was negotiated in part to provide that the water withdrawn from the affected area is put
to beneficial use for the municipalities. While importing Utah Lake water for treatment
and use would be an additional source of water for the area, this would do nothing to
contain or remove the contamination from. theBingham Canyon plume, the major goal of
this action.
22.Comment: Dansie Water Company opposes the proposed+moratorium on new
wells and increases in pumping rates because of the pollution caused by Kennecott.
Answer: There is already a moratorium on drilling of new weils and increases in
pumping rates that was imposed by the State Engineer in 1991 in Salt Lake Valley.
As stated by the Division of Water Rights, Kennecott has neither filed nor received
approval for a moratorium on arty groundwater development in the area. Zn199I the
State Engineer implemented the lnterim Ground Water Management Plan for Salt Lake
Valley which closed the entire valley to applications to appropriate ground water. The
State Engineer is currently in the process of developing a long term management plan for
the Valley. It is proposed that before new wells are drilled in the affected area the
101
impact on the water quality be considered and Kennecott be given an opportunity to
assist the water user in meeting their water requirements while at the same time insuring
that the diversion of water does not adversely affect the cleanup efforts. The State
Engineer is very aware of the property rights issues involved and is not attempting to
limit or adversely impact these rights.
23.Comment: Kennecott should be required to replace the water that they
contaminated. They should not only pay the cost of the connections but also the
cost of the water as well.
Answer: The ROD deals only with selection oft remedy to clean up the contamination.
It does not address liability or damages to private parties. The NRD Settlement does
deal with damages to the natural resources of the state.
24.Comment: The proposal should be rejected and more studies conducted. The
assumptions for the modeling should be given. Studies should include extra
modeling 0fthe drawdowns conducted by an outside consultant.
Answer: The studies of the plume have been going on since at least 1983 and under EPA
oversight since 1992. The model used by Kennecott in their projections of water level
drops and plume movement was ortginally developed by the U. S. Geological Survey
(TJSGS). Kennecott augmented the USGS model by providing a finer grid and additional
monitoring data. To test the model’s ability to predict the future, Kennecott conducted
several runs of the model beginning in 1965 when the reservoir was first installed,
continuing to the present. Some assumptions were modified in order to produce the best
fit. The model was also evaluated by sensitivity testing to determine which assumptions
were most critical to the performance of the model. The work of Kennecott was overseen
by modeling experts from EPA, by the USGS (under the funding of an Interagency
Agreement with EPA) and by the U49EQ Ground Water Protection Program. The lead
for the oversight was the person who actually developed the USGS model for the Salt
Lake Valley. EPA and UDEQ are satisfied that the model is adequate for decision
making and initial designs. The model uses established USGS and EPA methodology
and is used by hydrogeologic professionals worldwide. Of course, monitoring is apart
of the remedy io insure that there is adequate warning shouM the plume move in
unsuspected directions, or if draw downs are more serious than first thought.
25.Comment: Negotiations between Kennecott and Dansie Water Company are an
example of how Kennecott might handle other water fights owners.
Answer: The Dansie Water Company has unique problems in comparison with most
water rights owners. The primary difference is that the high TDS content present in wells
operated by the Dansie Water Company may not, in fact, be related to mining
contamination. The chemical content in the Dansie wells is not similar to the chemical
102
VII
content of other impacted wells in the valley. Another problem is that plans to bring
replacement water to the area are complicated by a legal action involving the Dansie
Water Company and its neighbors. Finally, the Dansie Water Company has tried to
couple their well issues with Kennecott into other areas of dispute with Kennecott. These
other issues are much more difficult than even the water issues by themselves. Other well
owners are not encumbered by such complications: The ROD selects a remedy for the
aquifer. It does not resolve private claims allow by law.
26."Comment: Kennecott should be declared a Superfund site. It will be hard to get to
Rio Tinto after Kennecott is no longer around.
Answer: An agreement, called a Memorandum of Understanding, was reached in 1995
between Kennecott, EPA and UDEQ in which the agencies agreed not to proceed with
listing of Kennecott on the National Priority List (NPL) so long as Kennecott performed
specific cleanups and studies in the agreement. Kennecott has continued to make
progress towards compliance with each of these provisions. The agreement was done as
an enforcement pilot by EPA to see ~f cooperative companies could clean up sites without
the stigma of listing on the NPL. The pilot has been viewed as a success.
Listing on the NPL has only one advantage. It is a requirement before the site is eligible
to use federal funding for Remedial Actions. (Remedial Actions are typically much
larger and more complex that Removal Actions). Since Kennecott indicated that itwill
fund the ground water cleanup without the use of taxpayer dollars, listing is superfluous
in this case. However, if circumstances change and listing becomes necessary to
implement his remedy, EPA will reconsider that option.
Listing on the NPL has no relation to liability questions. A party may be liable for
cleanups with or without listing. In this case, the provisions of what cleanups must be
done and what Kennecott must pay for will be detailed in a Consent Decree which will be
supervised by.the Federal Court in Utah. These requirements will need to be met
whether or not Kennecott is still operating. The Record of Decision merely establishes
the technical basis for the cleanup decision and provides the general approach to be
used It does not establish schedules or the actual design. Those details are typically
given in thework plan associatedwith the later Consent Decree. Listing on the NPL has
no effect on either the Record of Decision or the Consent Decree.
Letter from Rodney Dansie
7198 West 13090 South
Herriman, LIT 84065
27.Comment: The plan does not put water back to the affected area where surface
and ground water have been injured.
103
Answer: Note - this is apparently a NRD Consent Decree provision. CERCLA itself does
not require that the water beYput back" to the affected arecL
28.Comment: Water quality has degraded in the I-Ierriman area and this area has not
been included on the maps of affected areas. It should either be included in the
site, or designated as a separate site.
Answer: For CERCLA purposes, the Herriman area does appear on the map of the
"site’" in the Remedial Investigation Report. In the NRD Consent Decree, the "’affected
area" is defined as "’the area in the southwestern portion of Salt Lake Valley where
surface and ground water have been injured by Kennecott’s mining and leaching
operations. " See also previous response to #19.
Comment: The plan has not provided for replacement ofwaterin the area west of
Herriman where the water had been degraded.
Answer: For logistical reasons, the JP3~CD has agreed to provide service connections to
central locations. The nearest location in this case would be in HerrimarL Citizens can
negotiate with the town of Herriman to be included in their system when it is
implemented Private connections are also possible through negotiations with the
JPTze’CD.
30.Comment: The plan does not include provisions to replace and restore water in the
area west 0fHerriman. The plan should also pay for damages to the water
companies and water fights owners.
Answer: The purpose of the ROD is the selection of a remedy which will be used to clean
up the acid plume where the groundwater presents a risk to human health and the
environment. The ground water west of Herriman does not present arisk at yet. The
remedy addresses the Herriman area by prevention of leachate from entering the ground
water, and continuing to monitor the situation so that action may be taken shouM the
water quality degrade beyond background and begin to present a health risl~ High TDS
does not pose a health risk in and of itself.
The ROD does not determine liability of .any party. CERCLA has no provisions to settle
private damage claims caused by pollution. The replacement and restoration of natural
resources, such as water, are addressed in the Natural Resources Damage provisions of
CERCLA. The NRD Claim provisions provide that states, tribes, and the federal
government are the only groups which can bring claims for natural resources damages.
31.Comment: Water fights should be protected from unlawful taking. The plan does
not correct the problems of water degradation in the area west of Herriman.
Replacement water should be provided and damages paid to water rights owners.
104
Answer: The selected remedy does call for replacement of water supplies shouM the
drinking water be impacted by mining activities and pose a risk to customers. It does not
have authority to settle private claims for pollution damage.
32.Comment: The proposed plan has no provisions to deal with contamination in the
area west of Herriman. It should be included in the plan or separate one developed
for this situation. ’The area should receive treated water and be paid for damages.
Answer: At this time, water quality west of Herriman has not degraded to the point where
it presents a health threat to users. CERCLA does not deal with damages to private
parties due to pollution. This is handled privately between the parties involved
J
33.Comment: No replacement water has been provided for Dansie Water Rights.
Pollution may be continuing.
Answer: Efforts have been made under the provision of a Utah Ground Water Protection
Permit to prevent further contamination. Replacement water is a provision of the remedy
shouM the well water pose a health risk.
34.Comment: A plan on how to address the Dansie’s damages should be developed
and implemented before the Record of Decision is made. The should include an
estimate of when damages wilt be paid and when replacement water will be
provided.
Answer: The ROD does not address liability issues. Any negotiations regarding
damages have to occur between the parties involved EPA ’s authority, under CERCLA,
does not allow EPA to interfere in these matters.
35.Comment: Whatis the effect of the pump and treat of the acid plume on the
dropping of water levels in Herriman wells?
Answer: The amount of water level drops due to pumping of the acidplume will be a
function of the amount of water pumped lf water levels drop as a function of the
pumping, the effect will be most serious in the area of the acid plume gradually tapering
off toward the edge of the valley. Water level drops are a function of the pumping rates
in the entire area, including the pumping of the plume. Should water level drops be
noticed as a function of puml~ng in this project, the decline will be gradual and there
should be sufficient time to plan remedies for the private well owners. Each situation will
be handled on a case-by-case basis.
36.Comment: The model which predicts water elevation drops was prepared by
Kennecott and the District. Their studies should be reviewed by an outside
consultant.
105
Answer: See previous answer to #24. The model used has also been reviewed by the
governmental entities involved including EPA, USGS, and UDEQ.
37.Comment: Additional studies oft_he water level model and assumptions should be
conducted. A model is only as good as the assumptions used.
Answer: EPA and UDEQ agree that the ability of any model to predict the future is a
function of the assumptions used in it. For this reason, EPA and UDEQ will require that
a monitoringprogram be designed to refine assumptions for the ground water model and
to determine if the plume and drawdowns are behaving in reality as predicted by the
model. In addition, Kennecott and USGS have launched a new effort to better
understand water flow within the Oquirrh Mountains. This study might give better
information on flows within the bedrock aquifer and where the bedrock aquifer recharges
the alluvial aquifers in the Salt Lake and Tooele Valleys. The model is useful as a way to
compare performance of alternatives relative to each other. But monitoring is required
to determine if the plume is behaving as predicted Additional modeling efforts may be
needed if the plume is behaving differently than the original model predicted.
38.Comment: Kennecott proposes to use the clean water of the valley in their
treatment.ofwater they contaminated. This impacts the other water rights owners
in the valley. Kennecott should import water to clean up the plumes, rather than
using water owned by others.
Answer: The agencies do not understand what is being referred to in this comment. No
clean water is being used in the treatmentprocesses for either Zone A or Zone B. This
comment may refer to the area-wide drawdowns that may Occur during the process of
pumping the acid plume from the aquifer. Drawdowns are a co~. equence of trying to
remove as much of the acidplume in as short a time frame as possible. It is also an
effective way of providing a barrier to prevent further downgradient movement of the
plume. Kennecott has all the early water rights they need without using those of others.
Please note that the ground water is actually owned by the State of Utah. Individuals get
permission to develop the water under certain conditions as outlined by Utah Water Law
and the State Engineer.
39.Comment: Other alternatives should be’examined which do not rely on water from
the Herriman area or affect water levels in the Herriman area.
Answer: Water withdrawals are a necessary element to begin restoration of the aquifer at
this site. The size of the plume is so large and so deep that in-situ schemes would be very
costly and might not work at all. Drawabwns are an unpleasant consequence of water
withdrawals, but the impacts to other water users from these drawdowns can be
minimized or mitigated and these methods will be mentioned specifically in the Record of
Decision and the CERCLA consent decree.
106
40.Comment: Thank you for your efforts. Please require that additional work be
performed to address concerns.
Answer: The major scientific question which remains unresolved at this juncture is
whether the elevated TDS levels in the Dansie wells are natural or related to mining
activities. If a settlement between the parties occurs, this issue becomes moot. Ira
settlement is not reachea~ the source of the elevated TDS becomes important in
determining if this well is included in the CERCLA actiorL CERCLA does not require
cleanups of any naturally occurring substances or when contaminants do not pose a
threat or potential threat to human health or the environment.
VIII Letter from Steve Maxfield
9I Canyon Rd
Herrimart, UT 84065
41.Comment: I would like to know about the impacts of the cleanup plan on my well.
(A culinary well in Hi-Country Estates, Phase 1)
Answer: The water level drops which might occur because of pumping of the acid plume
are most likely to be felt near the acid plume and less so towards the edges of the valley.
Wells installed in other aquifers are unlikely to be impacted
42.Comment: I am concerned that continuing natural and,leaching activities to the
west will affect the quality of the water in my well.
Answer: The leach waters emanating from the mining area are now being controlled with
cutoff walls in the Butterfield Canyon gulches under the provisions of a Utah Ground
Water Protection permit. Natural leaching, although it can cause poor water quality,
falls outside the authority of CERCLA.
43.Comment: EPA should protect water rights owners in this area from
contamination and drawdown orwater tables.
Answer: EPA and UDEQ are concerned when private wells are impacted from industrial
sources. Drawdowns due to over pumping are generally in the purview of the State
Engineer’s office. In this project, a separate provision has been added to deal with
drawdowns resulting from this project,
44.Comment: Other water should be imported for the cleanup water processing rather
than mining the water in the area.
107
Answer: See previous answer to #21.
X
45.Comment: The mining company should not be able to take remaining water to
clean up the contamination that they created.
Answer: As far as is known about this project, no clean water is being used in the
cleanup.
Phone message from Vielde Walker
7536 W 13323 South
Herriman, LIT 84065
46.Comment: I am concerned about the drawdown within the aquifer.
Answer: The ground water model developed by USGS and Kennecott suggests that
pumping of the acid waters from the plume associated with Bingham Canyon will drop
water levels as far away as Herriman and possibly to 1300 Wand 10600 S. The model is
simply a prediction tool that is only as good as our current knowledge of the ground
water in the area; therefore, a continuing monitoring program which will monitor water
levels and water quality in the area will be implemented Cooperation with private well
owners is vital to the success of this monitoring program. Monitoring information can
then be used to refine the calculations and model and give an early warning if water
levels are affected by pumping in this project and/or pumping by otherparties. A
separate provision in the remedy has been added to deal with draw downs shouM they
occur as a part of this project.
47.Comment: What will be the compensation plan if her well is affected?
Answer: Corrective action may include substitution with water from another source such
as municipal water or Kennecott sources, deepening of the impacted well, or treatment of
private well water using a residential reverse osmosis treatment system.
48.Comment: I would like to be hooked up to city water.
Answer: If a private welt is found to be impacted by acid plume remediation, the
compensation will be worked out by the parties involved
Phone message from Bob Bowles, property owner in Herriman
49.Comment: I am ooneerned about the drawdown in the aquifer and how that might
affect my four irrigation wells south of Herriman.
108
XI
Answer: The ground water model developed by USGS and Kennecott suggests that
pumping of the acid waters from the plume associated with Bingham Canyon will drop
water levels as far away as Herriman. The model is simply a prediction tool that is only
as good as our current knowledge of the groundwater in the area; therefore, a
continuing monitoring program which will monitor water levels and water quality in the
area will be implemented Cooperation with private well owners is vital to the success of
this monitoring program. Monitoring information can then be used to refine the
calculations and model and give an early warning if water levels are affected by pumping
in this project and/or pumping by others. A separate provision in the remedy has been
added to deal with drawdowns should they occur as a part of this project.
50.Comment: What compensation will I get if my wells become useless (go dry). This
should be put in writing.
Answer: Corrective action may include substitution with water from another source such
as municipal water or Kennecott sources, deepening of the impacted wells, or treatment
of private well water using a residential reverse osmosis treatment system. The concept
of addressing impacts due to drawdowns is included in the Record of Decision. Each
water well owner will be dealt with separately for the solution most appropriate to the
situation.
Phone message from Eileen Brooks
12680 South 3600 West
P,i’verton, UT 84065
51.Comment: What compensation will Kennecott provide if contamination increases
in my well water? Can I get my well tested?
Answer:The well in question is owned by Ms. Brooks’ mother, Elma Johnson and is
located at 12872 S 3600 W. It is identified as t-lMG1548 by Kennecott and was sampled
as part of the well inventory project in 1994. The results of this project showedno
evidence of mining impacts (68 mg/L sulfate) and that well is south of known
contamination and any known contamination sources. Given its location away from the
contamination, it is not likely the well wouM need to be resamplea~ but it is possible that
water level information would be collected It is also outside the area of predicted draw
down associated with acid plume pumping.
XII Public Hearing Testimony: Betty 1~aylor - none of comments regarded the CERCLA
portion of the action. Ms. Naylor’s questions were referred to UDEQ for response as a
part of the NRD settlement proposal.
109
XIII
XIV
Public Heating Testimony: Steve Hansknecht
52.Comment: Kennecott used their water tights in Buttertield Canyon at the expense
of the downstream farmers and the court made a mistake to let them do it.
Answer: There were several lawsuits involving water rights in ButterfieM Canyon in
which the farmers in Herriman claimed that the mining companies had interfered with
their water rights. Most of these lawsuits predated Kennecott’s ownership of the land
and the water rights. There were continuing disputes after Kennecott gained the water
rights, but these were usually settled ~or example, Kennecott did give the Herriman
Irrigation Company water from the Bingham Tunnel so long as it was not needed in their
processing. Kennecott later indicated that the water was needed in processing and the
water to the irrigation company was cut off. The water was contaminated by arsenic and
the state objected to its use for irrigation also. EPA and UDEQ concur with the citizen
that the continual ftghts between the farmers and the miners in this area were unpleasant.
53.Comment: It is better to let Kennecott get the copper out of the water, then treat it
for people to use than to let it go to the JordanRiver. I’m glad somebody finally is
doing something about it.
Answer: EPA and UDEQ concur,
Public Heating Testimony: Rod Dansie
54.Comment: The plan is a good one to try to clean the water up. I am concerned
about the Herriman area water.
Answer: The main effect of this project in Herriman is a potential drop in water levels.
Although the model gives an idea of how severe it might be, the situation will need
continual monitoring as the project proceeds.
55.Comment: I’m not convinced that the model will do what they say. Kennecott
thinks the water will come up from the bedrock. I’m not convinced it will.
Answer: The model is only a projection of what might happen based on what we know
now. Continual monitoring will be needed as the project proceeds to determine what the
recharge is and where.
56.Comment: The agencies should bring in water from Utah Lake or the Jordan
River, not to West Jordan, but to Herriman.’-We need to get water back to the
area where draw downs will occur.
II0
Answer: This is a NRD question. CERCLA doesn’t require that water be returned to the
impacted area~
57.Comment: Maybe the water can be cleaned used in the taps, then let it go back
into the ground. This is better than cleaning up the water only to reinject it into
the aquifer without using it first.
Answer: The idea of reinjection of the water back into the aquifer was controversial.
Those concerned with water supply indicated that this was a waste of a valuable
resource. Several scientists questioned whether it was a good idea to clean up the water
and reinject it only to have the same water be contaminated again. Modeling suggested
that cleanup time frames would not be shortened by this strategy. The only potential use
would be as a method to protect nearby municipal well fields.
58.Comment: In the past, the state engineer rejected change applications on the basis
that the water was being taken from one aquifer and used in another, recharging
that aquifer instead of the one from which the water was originally taken. Does
this plan do the same thing?
Answer: This is possible. According to the Division of Water Rights, in the evaluation of
change applications, the State Engineer’s management plan does not allow changes from
the shallow ground water aquifer to the deeper principal aquifer. Also, a change
application which proposes to transfer a water right to a different area is critically
reviewed. The proposed project will require water right applications and they will be
evaluated by the State Engineer according to Utah Water Law statues and using the
guidelines set forth in the ground water management plan. Kennecott indicates that it
owns water rights in both the principal aquifer and the bedrock aquifers in the Oquirrh
Mountains. 31/WCD owns rights in both the principal and the shallow unconfined
aquifers. Waterrights may need to be transferred to accommodate this plan. The State
Engineer has tom Kennecott that he will allow transfer out of the principal aquifer to
other aquifers, but not vice versa.
59.Comment: Something should be built into the plan so that individUals will not
have to battle each time to prove interference. Individuals know how,their wells
behave, but it is hard to prove interference.
Answer: For most circumstances, interference will be rather simple to prove because
water levels in nearby wells will be similarly impactecL There will be area-wide impacts
on water levels. No special mechanism or criteria is needed See also previous response.
60.Comment: Kennecott dumped major amounts of sulphuric acid on the dumps 20
or 30 years ago. Some leaching occurred south towards Butterfield Canyon, but
not a lot.
111
Answer: Kennecott andprevious operators in the area were heavily engaged in leaching
of the waste rock dumps. The record is clear on that point, and Kennecott hasnot denied
this. Today groundwater and surface water in ButterfieM Canyon are monitored as
required by a Utah Ground Water Discharge Permit. The results indicate that a few of
the wells show elevated su~ate and some of the meteoric leach water draining from the
dumps is slightly acidic. These impacts are most likely a result of meteoric leaching of
the South Mine Waste Rock Dumps which wei"e not infused with sulphuric acid Ground
water monitoring and an independent study conducted by the University of Utah
indicates that the path of ground water from the dumps that were infused with acid is
ch’rectly east, not south to the Herriman arec~
61.Comment: It is great that this project will bring water to Herriman, but Herriman
Town does not own water rights, the private well owners and companies do. The
water is not going tothe water rights owners who have been impacted.
Answer: The division of the water is apart of the NRD settlement. That is a matter for
negotiations between the municipalities, the JVWCD and the State Trustee. According
to the JVWCD, the proposed plan submitted to the State Trustee will use municipal and
industrial water rights in the affected area to provide tre~tted water to the public in the
affected area. The only M&I ground water rights currently in the affected area belong to
JVWCD, Kennecott, Riverton City and West Jordan City. However, the entire public in
the affected area will benefit under the proposed project, not just a few private water
right holders.
62:Comment: Our water rights are significant and we worked on them for 50 years to
bring water to our properties.
Answer: Utah water law is based on the prior appropriation doctrine, which is first in
time, first in right. In any action by the State Engineer a fundamental part of his review
is to insure that they do not affect prior water rights without just compensation.
Comment: It will be hard to establish responsibility on a case-by-case basis and
some plan for arbitration should be included so that legal fees are not incurred.
Answer: Responsibility in most situations will be obvious and clear-cut. Degradation due
to mining is typically indicated by rising sulfate levels and water levels will be affected
over a wide area. Arbitration is not needed for most of these situations. The Dansie case
is a fairly unique situation. If disputes arise in the future, any party has the right to
suggest the use of alternative dispute resolution procedures to resolve such disputes.
See also previous response.
112
2
XV
XVI
64.Comment: Water should notcome back to a community [Herriman Town] that has
no water rights, and there is no guarantee that the water won’t be marked up. It
could be a slush fund for the city that needs taxes. This doesn’t benefit the people
that developed the water rights.
Answer: The decision on how the water is allocated is a matter for determination by the
State Trustee. As stated by JgWCD, the cooperating water purveyor, it is assumed that
the Town of Herriman will act responsibly to its residents in distributing and selling
treated water from the project plants delivered to it by JVWCD on a wholesale basis.
JFWCD will make other retail deliveries to its residents not served by the Town of
Herriman under its normal Rules and Regulations for Retail Water Service, where it has
present and future distributionfacilities..
Public hearing testimony, Tom Bechak
65.Comment: It’s a wonderful thing that’s being done to control and contain the acid
plume in Zone A, but my well is in an area where the water levels might drop 120
feet. I’m concerned about th~tt.
Answer: The groundwater model developed by USGS and Kennecott suggests that
pumping of the acid waters from the plume associated withBingham Canyon wil indeed
drop water levels in the area of Mr. Belchak’s welI by approximately 120feet over a 50
year period. The model is simple a prediction tool that is only as good as our current
knowledge of the ground water in the area; therefore, a continuing monitoring program
which will monitor water levels and water quality in the area will be implemented
Cooperation with private well owners is vital to the success of this monitoring program.
Monitoring information can then be used to refine the calculations and model and give
an early warning if water levels are affected by pumping in this project and~or pumping
by other parties. Corrective action may include substitution with water from another
source such as municipal water or Kennecott sources. Mr. Betchak has already been
drilled a new well at Kennecott’s expense.
Public hearing testimony, Mike Barela
66.Comment: If my well goes dry, how long will it take to get water up there?
Answer: Any area-wide drop of water levels due towater withdrawals from the acid
plume will be gradual, occurring over several years. There will be sufficient time to take
action before impacts become serious. Mr. Barela’s well is located at 13320 S 7565 Win
the Rose Canyon. Area. It isjust outside the model predicted area of influence, but if
drawdown is more than predicted at this location, corrective action will be taken. By the
time this well is affected, JVWCD will have infrastructure in the area and a connection
can be made in a short period of time.
I13
XVII Public hearing testimony, Rod Dansie
67.Comment: An additional meeting should be held in Herriman.
request for this.
I make a formal
Answer: Herriman residents with water rights within the site were all mailed an invitation
to participate in this hearing. In addition, a newspaper advertisement invited written
comments from those who chose to use this method to convey their views. Opportunities
were also given to water users to meet with the scientists and engineers on a one-to-one
basis. A number of residents of Herriman have participated in these ways. An additional
meeting is not needed
114
B. Technical Issues
Technical Issues:
Plume behavior: There are a number 0funcertainties regarding plume behavior over time,
despite the extensive model development and calibration. The model itself is widely used in the
field 0VIODFLOW coupled with MT3D). It w~ used originally by USGS to develop the.Salt
Lake Valley Ground Water Model, and later refined in the RIFFS. Flow rates in the aquifer were
verified by several means because historical groundwater data were available and the history of
releases to groundwater were known. Even isotopic tracing techniques were used to provide
independent verification. Yet, it is still a model and relies on the validity of the assumptions used
in it. Although the assumptions are based on a rather large number of observations, the area
affected is quite large and not every square inch of the aquifer was sampled. Undetected buried
channels might provide preferential flow pathways causing the plume to move in an unanticipated
direction and do so more rapidly than predicted. Hidden clay lenses could serve as a barrier
thereby either diverting the plume or causing it to travel more slowly than expected.
This uncertainty common to the application of all groundwater models produces an uncertainty in
the absolute time it might take for remediation of the aquifer.
A further complicating factor in the case of this particular plume is the variety of chemical
reactions that take place in the aquifer itsel£ This occurs because the acid plume reacts with the
carbonates in the aquifer substrate to form a variety of metal oxides and hydroxides. It is not a
matter of simply neutralizing the hydrogen ion because the majority of the acidity is "mineral
acidity" largely from the high aluminum concentrations and this must be neutralized as well.
Formation of these solid phase precipitates in the aquifer substrate may change the flow
characteristics of the aquifer. These solid precipitates will begin to redissolve back into the
groundwater when fresh water is introduced. Column testing has shown that it could take at least
7 pore volumes of water before these precipitates are redissolved and flushed away. Calculations
suggest that the vast majority of the acid groundwater can be pumped out of the aquifer in 30 - 50
years, but the residuals could leach back into the water for many years after the initial plume has
been removed. Although this can be modeled, the time this would take is highly uncertain and
might continue for decades or longer. EPA believes that for funding and planning purposes,
treatment wiU have to continue in perpetuity.
In addition to the=uncertainty in the time frame required to clean up the plume, there is
some concern with regardto the direction of plume movement under different pumping rates by
the adjacent communities. Of particular concern is the wall field of West Jordan located just to
the north of the acid plume. The modeling did show that under some pumping scenarios the
plume could be drawn in that direction. A monitoring well has been driUed between the acid
plume and the West Jordan well field to provide an early warning should this occur. A similar
concern was expressed with regard to wells located on the east side of the Jordan River. Could
high pumping from wells in Sandy, Utah, for example, draw the contamination underneath the
115
river? Carefulmonitoring will be necessary to detect any unexpected changes and to revise time
estimates.
Modeling suggests that at the maximum pumping rates needed to remove the acidic waters
quickly, excessive draw downs of the water levels in the aquifer will occur locally around the acid
wells and the nearby West Jordan municipal well field. Several proposals have been examined to
mitigate this problem. One idea is to inject clean water between the acid plume and the West
Jordan municipal well field to offset the water level drops. Modeling suggests this idea w~l work,
but some indicate this is an inefficient use of clean water. Another possibility is that freshwater
from the mountains be piped directly to West Jordan City in case their v~611 field becomes
contaminated or non-productive. This issue is still under discussion.
Treatment uncertainties: Both the reverse osmosis treatment technology and the
nanofiltration technology have been tested in pilot projects. The acid plume waters cannot be
treated directly using the reverse osmosis technology due to excessive scaling of the membranes.
The technology performs well with the waters from less contaminated wells. 2qanofiltration is
proposed for pretreatment of the most contaminated waters with the permeate going to further
refinement in the reverse osmosis facility. However, the operational details ofthenan0filtration
technology have not been optimized and this may vary as the concentrations of the plume
changes. It may take 5 years of operating experience with the pretreatment plant before routine
operations are feasible.
Disposal uncertainties: Pilot testing of disposal of acid waters into the tailings slurry
pipeline have been ongoing for the past year. An initial problem of excessive scaling on the inside
of the pipeline originally occurred resulting in a tailings overflow near the point of entry. After
acid additions ceased, the tailings scoured the scale deposits out the pipeline, so no cessation of
operations was necessary to clean out the pipeline. Experiments then revealed that no scale
formed if the sulfate concentrations were less than 5000 ppm when added to the slurry line.
Monitoring of the supematant water in the tailings pond at the terminus 0fthe pipeline did not
reveal any increases in metals or TDS concentrations over typical concentrations with the acid
additions. Laboratory experiments indicated the metals in the original acid solution had
precipitated, and were not simply diluted. The supernatant water is recycled during the summer
and the rest evaporates. There is no discharge. In the winter, excess water is discharged to the
Great Salt Lake. Since the concentrate flows in the railings line represent only a very small
fraction of the water, no exceedances of the NPDES discharge are anticipated.
There are two difficulties with this strategy. (1) This strategy works only while the
Copperton Concentrator (which grinds the ore and separates metal bearing components from the
host rock by flotation) is operating. Sufficient storage capacity for the acid waters must be
provided during routine shut downs for maintenance. Emergency shut downs due to power
failures or labor troubles must also be considered. (2) This strategy will also work only during the
life of mining and milling operations at the site. Another method of disposal will be neededupon
mine closure. There are several possible alternatives here, some of which might be integrated
116
with Other waste water disposal needs following closure. Provisions should be included in the
brine Closure Plan.
One of the proposals for disposal after mining ceases in 30 years is direct disposal of the
treatment concentrates into the Great Salt Lake. Although technically feasible, there are
numerous policy issues which need to be examined before this can be considered. For example,
today there are no numerical water quality standards for any constituent in the Great Satt Lake.
Therefore, the potentialimpacts cannot be judged. In the next 30 years, it is hoped that more will
be known about the ecology of the Great Salt Lake and the impacts 0fpollutants on that ecology.
117
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SDMS Document ID
tEIIIHI I
2025179
EXPLANATION OF SIGNIFICANT DIFFERENCES
KENNECOTT SOUTH ZONE OPERABLE UNIT 2
SOUTHWEST JORDAN RIVER VALLEY GROUND WATER PLUMES
U. S.Environmental Protection Agency, Region VIII
999 18~ St. Suite 300.
Denver, Colorado, 80202
BACKGROUND
In December, 2000, EPA and UDEQ signed a Record of Decision which se]ected a
remedy for the Zone A ground water plumes associated with past mining activity in the Oquirrh
Mountains. During the design phase of the project, Kennecott Utah Copper Corp. (KUCC)
conducted treatability studies to refine flows and treatment parameters and to combine the
infrastructure associated with this project with similar infrastructure needed to manage other
contaminated flows at the mine. These new concepts and study results have led to some minor
changes in the selected remedy as chosen by the Record of Decision. The overall approach to the
problem and ability to meet the stated objectives remain unchanged.
COMPARISON OF SELECTED REMEDY (as given in the Record of Decision) AND THE
REMEDIAL DESIGN (as detailed in the Final Design for Remedial Action)
Remedy in Record of Remedy in Design Phase Differences, if any
Decision
III
Operations and maintenance Not specifically mentioned in Surface source controls not
of surface source controls the Remedial Design. O+M addressed in Remedial
of the source controls is Design document. This is
addressed in a State Ground required in a State Ground
Water Permit.Water Permit.
Integration and use of Restrictions on use of water The State Ground Water
Institutional Controls, as from existing wells,Management Plan issued by
approved by the State restrictions on installation of the State Engineer in June
Engineer new wells, moratorium on 2002 addresses issues
new water fights will be specific to the remediation
established through the State effort and needed restrictions
Engineer as needed.in the area of the plumes.
==
Point of Use Management for Plan for addressing impacts Same
private well owners (in-home to other well owners was
treatment units, bottled water,developed. Work with
deepening of wells,owners to develop best form
replacement of wells)of reparations.
Remedy in Record of Remedy in Design Phase Differences, if any
Decision
|,
Plan to deal with Options include reduced Same
consequences of water level pumping, replacement water,
drops (new and deeper wells,injection, deeper well
deeper completions in wells,installation
alternate water sources,
purchase or exchange of
water rights), well
abandonment and
compensation.
ii m,i
Install a barrier well Three wells to serve as an Same
containment system at initial barrier well system
leading edge of acid plume at have already been installed
points in path of movement
(where sulfate is less than
1500 ppm). No water with
sulfate concentrations greater
than 1500 ppm should move
off Kennecott property.
Install well or wells in core ofTwo wells to operate at any Same
acid plume time. Wells moved in
response to plume
Pretreatment of acid water Acid water sent directly to Nanofiltrafion step eliminated
using nanofiltration tailings line without in final design.
preta’eatment. Neutralization
and metals removal takes
place in the tailings line.
Neutralization by tailings can
be augmented with lime if
needed.
mm
Treatment of pretreated acid Not relevant any more No pretreatment of acid
waters by Re waters. Treatment of acid
waters occurs in tailings
lines, not by Re plant.
,J
Treatment ofwater from Treatment of water from Same
barrier wells by Re sulfate barrier wells by Re
Remedy in Record of Remedy in Design Phase Differences, if any
Decision
¯ii
Treated waters to municipal Treated waters from sulfate Acid waters are kept by
water purveyor wells sent to JVWCD, acid Kennecott for use in
waters kept by Kennecott for processes, and are not sent to
use in milling processes.a water purveyor.
Install and maintain a Monitoring system plan Same
monitoring system to track presented
plume movement
i |J
Prior to mine closure, dispose Acid water and RO Very similar
of concentrates in the railings concentrates added to tailings
line line
i I II
Post Closure plan should be Post Closure Conceptual Same
developed during RD/RA design options presented
which can be implemented
quickly.
EXPLANATION OF DIFFERENCES
In the process of designing the remedy, the approach to treating the waters withdrawn
from acid plume was changed. Originally, the waters from the acid plume core were to be
pretreated using nano-fiitration technology. The permeate was then to be further treated using
reverse osmosis, with the concentrate recycled to the waste rock dumps for use in active leaching
of the waste rock. However, since this approach was studied and advocated, Kennecott
discontinued the active leaching of waste rock. This makes the concept of re-use of the
concentrate for leaching no longer available. With the cessation of active leaching, Kennecott
began experimentation on treatment of the residual leaehate and leachates produced with
precipitation falls on the dump areas. A study during the design phase indicated that insertion of
the acid waters into the tailings pipeline was feasible. The tailings, which contain carbonates,
were able to neutralize the acids. The tailings line, therefore, serves as a 13-mile long acid
neutralizing facility. The neutralization capacity is required in the railings line whether the nano-
filtration concentrate waters are neutralized or the acid plume waters themselves are neutralized.
Further studies revealed that the neutralization process was actually completed in the first few
hundred yards of the pipeline. The experiments further proved that both waste streams, the
residual )eaehate water from the dumps and the acid waters removed from the aquifer, could be
treated effectively in this manner. The resulting water with its soluble components is not of
drinking water quality and therefore will not be provided to the municipalities. Instead, it would
be recycled and used in Kennecott’s processing, especially at the Copperton Concentrator. One
of the principles in the National Contingency Plan (NCP) indicates that water generated by
treatment of contaminated aquifers should be put to beneficial uses. Although the water will not
go to municipal culinary use, it will have a beneficial use as industrial water.
Calculations have also revealed that treatment of the acid plume is not cost-effective
because the acid plume is of such poor quality. Although such a scheme was proposed in the
RI/FS and agreed to in the ROD, only 24% of the acid plume waters would actually go to
drinking water and the rest would end up in the tailings pipeline (and then for industrial use).
For this small volume of drinking water product, the cost would be about $6-7tl 000 gals.
Treatment of the less contaminated waters at the barrier wells is much more cost-effective and
can be done with less waste of the water. The cost of treatment of barrier well water is
$0.70/1000 gals.
In terms of operations of the barrier well reverse osmosis treatment plant in Zone A,
Kennecott will construct and operate the plant for the first 5 years at least, perhaps longer. This
is to allow time for Kennecott to develop the operational parameters and costs so that long-term
management negotiations can proceed. Kennecott may choose to operate the plant indefinitely so
that the facility can be expanded and integrated with Kennecott’s industrial water management
system. As is the original plan, the treated water from the reverse osmosis plant will go to
JVWCD and the treatment concentrate to the tailings line.
Scientists agreed very early that effectiveness of source control infrastructure was
extremely critical in cleaning up the aquifer. The cut-offwalls and pipelines associated with
these source control measures were constructed and are now maintained through provisions of a
state groundwater protection permit. Because of its importance to the cleanup program,
maintenance of these source controls was listed as an element of the ROD of December, 2000.
The source control maintenance is not described in the remedial design because this is already
included in the groundwater permit. The p .arties remain committed to thispart of the remedy.
Maintenance of the source control facilities will continue either under the auspices of the
groundwater permit or under terms of the federal RD/RA Consent Decree.
CONCLUSIONS
Although some of the treatment details presented in the Remedial Design are different
than detailed in the ROD, the overall approach remains unchanged. Unchanged is the concept of
barrier wells which prevent spread of the contamination. Unchanged is the withdrawal of the
heavily contaminated waters from the core of the acid plume so that the plume diminishes in size
over time. Unchanged is the approach for beneficial use of the waters withdrawn from the
plume, a concept which works for both the waters treated in the reverse osmosis plant and in the
tailings pipeline.
Max H. Dodson Date
Assistant Regional Administrator
Office of Ecosystems Protection and Remediation
U. S. Environmental Protection Agency, Region VIII
D~e R. Nielson, Ph.D.
Executive Director
Utah Department of Environmental Quality
Date
Explanation of Significant Differences
Kennecott South Zone, Operable Unit 2
Southwest Jordan River Valley Ground Water Plumes
U.S. Environmental Protection Agency, Region 8
Utah Department of Environmental Quality
June 2007
Introduction
The Kennecott South Zone Site, proposed for the National Priorities List (NPL) in 1994,
is located in southwestern Salt Lake County, Utah, about 10 miles southwest of Salt Lake
City. Operable Unit 2 (OU2) of th~Site, known as the Southwest Jordan River Valley
Ground Water Plumes, encompasses the groundwater beneath all or portions of the
municipalities of West Jordan, South Jordan, Riverton, Herriman, and portions of
unincorporated Salt Lake County. A Record of Decision, selecting a remedy for OU2, is
dated December 13, 2000.
The remedy was modified with an Explanation of Significant Differences (ESD) in
August 2003. This June 2007 Explanation of Significant Differences is the second ESD
to modify the original remedy. While the overall approach to this Site, and the ability to
meet stated objectives, remains unchanged, certain refinements to the original remedy (as
modified by the first ESD) are necessary.
This Explanation of Significant Differences (ESD) describes the rationale for modifying
the remedy specified in the Record of Decision (ROD) and first ESD for Operable Unit 2
of the Kennecott South Zone Site. Section 117(c) of CERCLA, 42 USC §9617(c), and
the National Contingency Plan (NCP), 40 C.F.R. Section 300.435(c)(2)(i) require that an
ESD be prepared when the differences in the Remedial Action significantly change but
do not fundamentally alter the remedy selected in the ROD with respect to scope,
performance, or cost. ,
This ESD is supported by and will become part of the Administrative Record file for this
Site, in accordance with the NCP, Section 300.823(a)(2). The Administrative Record is
available for review at UDEQ’s office located at 168 North 1950 West, Salt Lake City,
Utah. Key documents and reports are also available for review at the City Recorder’s
Office, City of West Jordan, 8000 South Redwood Rd, West Jordan, UT 84088.
Site History
The Kennecott South Zone Site is composed of historic mining sites, of surface areas
contaminated by mining wastes which migrated from source areas downgradient to cities
and towns, and of subsurface areas contaminated by acid leachates from the mining
district. The Kennecott South Zone Site is comprised of fifteen operable units.
The remedy selected for the Kennecott South Zone Operable Unit No. 2 - Southwest
Jordan Valley Groundwater Plumes, involves treatment and containment of contaminated
ground water. The principal sources which caused the ground water contamination have
been addressed in previous actions or are managed by Kennecott under provisions of a
¯ Utah Ground Water Protection Permit.
The selected remedy, as modified by the first ESD, contains the following elements:
Continuation of source control measures as administered through the State of
Utah Ground Water Protection Program.
Prevent human exposure.to unacceptable high concentrations of hazardous
substances and/or pollutants or contaminants by limiting access to the
contaminated ground water. The State Ground Water Management Plan,
issued by the State Engineer in June 2002, addresses issues specific to the
remediation effort and needed restrictions in the area of the plumes.
Prevent human exposure to unacceptable high concentrations of hazardous
substances and]or pollutants or contaminant through point-of-use management
which includes providing in-house treatment units to residents with impacted
wells, replacement of their water by hooking the properties up to municipal
drinking and/or secondary supplies, and/or modifying their wells to reach
uncontaminated waters.
Contain the acid plume in Zone A by installation of barrier wells at the
leading edge of the contamination (1500 ppm sulfate or less), pump and treat
the waters to provide a hydraulic barrier to prevent further plume movement
while providing treated water for municipal use. The treatment technology for
the barrier well waters is reverse osmosis.
Withdraw the heavily contaminated waters from the core of the acid plume in
Zone A and send it directly to the tailings line. Neutralization and metals
removal takes place in the tailings line. Neutralization can be augmented with
lime if needed.
Monitor the plume to follow the progress of natural attenuation for the
portions of the Zone A plume which contain sulfate in excess of the primary
drinking water standard for sulfate (500 ppm sulfate).
Disposal of acid water and reverse osmosis concentrates in existing pipeline
used to slurry tailings to a tailings impoundment prior to mine closure.
Development of a post-mine closure plan to manage extracted acid core water
and reverse osmosis treatment concentrates (derived from the management
option selected for the water extracted at the leading edge wells) for use when
the mine and mill are no longer operating.
Basis for and Description of the Significant Differences
A number of clarifications to the remedy are required to address barrier well water
management, source control measures for the Eastside Collection System and Bingham
Reservoir, and performance standards.
1)Water Management
The December 2000 ROD selected treatment of barrier well water using reverse
osmosis and delivery of treated water to a municipal water purveyor. This clarification to
the remedy is to allow other management options for barrier well water including
continued use by Kennecott for industrial needs or the provision of raw or treated barrier
well water for any other lawful use that is both consistent with the quality of the water,
previous decision documents and acceptable to EPA and UDEQ.
2)Source Control Measures
The original remedy indicates that source control measures (i.e., Eastside
Collection System, Bingham Reservoir) are to be operated under State permits. As a
clarification, these permits are considered complimentary to the OU2 remedy and
management of the Southwest Jordan Valley Groundwater plumes. UDEQ will provide
routine reports to evaluate compliance with State permits. In the event that State permits
and/or programs are ineffective in controlling potential sources of contamination to the
groundwater plume, additional Federal CERLCA response actions may be required. At a
minimum, Kennecott’s compliance with applicable State permits will be evaluated no
less often than every five years pursuant to the CERCLA requirement to conduct a Five
Year Review whenever waste is left in place precluding unrestricted use and unlimited
exposure.
3)Performance Standards
There are three performance standards related to the rate of extraction from the core of
the plume in Zone A, plume containment, and cleanup levels to demonstrate the
effectiveness of the remedy.
A)Extraction Rate
Several wells have been installed for the extraction of heavily
contaminated water from the core of the acid plume in Zone A. The change in
this ESD is to define a rate of extraction to assure reduction in the size of the
contaminated plume. As of the time of the writing of this ESD, that extraction
rate has been established at a minimum of 1200 acre-feet per year from the core
of the acid plume, on a five-year rolling average. The extraction rate may be
modified pursuant to the Operation, Maintenance and Replacement (OM&R)
Plan.
B)Containment
Another change from the 2000 ROD is that a series of compliance points
has been established along the northern, eastern, and southern boundaries of the
Zone A Plume. These points of compliance are identified in the OM&R Plan.
The points of compliance may be modified pursuant to the OM&R Plan.
C)Cleanup Levels
The final cleanup levels for active remediation are given in the following table:
FINAL CLEANUP LEVELS FOR ACTIVE REMEDIATION
Contaminant Cleanup Levels Throughout the Acid Plume
(dissolved concentrations)
pit pH = 6.5 - 8.5
Arsenic 0.05 rag/1
Barium 2 mg/l
Cadmium 0.005 rag/1 ...........
Copper 1.3 mg/l
Fluoride 4 mg/1
Lead 0.015 rag/1
Selenium 0.05 rag/1
JNickel 0.1 mg/l
Sulfate*1500 m~l
* Once sulfate has reached 1500 mg/1 throughout the plume, active remediation may be
discontinued in favor of monitored natural attenuation until sulfate concentrations
throughout the plume reach 500 mg/1.
Nitrate has been deleted as a contaminant of concern since nitrate concentrations have
consistently been well below the groundwater protection limit.
Treatment levels for the reverse osmosis treatment plant have been deleted since the
water treatment plant is operating under a permit with the Utah Division of Drinking
Water.
The method for determining when final cleanup levels have been met will be identified in
the OM&R Plan when the groundwater quality in the plume approaches the final cleanup
levels.
Comments from Utah Department of Environmental Quality
The Utah Department of Environmental Quality (UDEQ) supports EPA’s decision to
modify the remedy for Operable Unit 2 of the Kennecott South Zone Site.
Public Participation
EPA published a notice in the Deseret News and Salt Lake Tribune newspapers that
described the ESD and its availability for review (under Section i 17(c) of CERCLA, 42
U.S.C. Section 9617). While a formal public comment period is not required when
issuing an ESD, EPA and UDEQ provided an opportunity for the public to comment.
Following a 30-day comment period, a responsiveness summary was prepared in
response to comments received. This ESD, and all documents that support the changes
and clarifications, are contained in the Administrative Record of the Kennecott South
Zone Site (under 40 CFR, Section 300.435(c)(2)(i)).
Statutory Determinations
Under CERCLA Section 121, EPA must select a remedy that is protective of human
health and the environment, complies with Applicable or Relevant and Appropriate
Requirements (ARARs), and is cost effective. EPA believes that the modifications to the
ROD for the Southwest Jordan River Valley groundwater plumes are appropriate and the
remedy will remain protective of human health and the environment. The selected
remedy will continue to comply with federal and state requirements that are applicable
and relevant and appropriate to the remedial action. This ESD does not fundamentally
change the remedy and is cost effective.
Section 121 also states that EPA must select a remedy that uses permanent solutions,
alternative treatment technologies, or resource recovery technologies to the maximum
extent practicable. In addition, CERCLA prefers remedies that include treatment that
permanently and significantly reduces the volume, toxicity, or mobility of hazardous
waste as a principal element of the remedy. The selected remedy uses treatment as a
principal element in remediation of the aquifer and meets the statutory requirement.
Date

Carqt~ushin " " ] ....
Assi~’tant Regional Administrator
Ecosystems Protection and Remediation
US EPA Region 8
Date Dianne R. Nielson, Ph.D.
Executive Director
Utah Department of Environmental
Quality