FACT SHEET
NPDES Permit Number: ID0027022
Public Notice Start Date: June 24, 2002
Public Notice Expiration Date: July 24, 2002
Technical Contact: Kristine Koch, (206) 553-6705
1-800-424-4372 ext. 6705 (within Region 10)
koch.kristine@epa.gov
The U.S. Environmental Protection Agency (EPA)
Proposes to Reissue a Wastewater Discharge Permit to:
Meridian Beartrack Company
Beartrack Mine
P.O. Box 749
Salmon, Idaho 83467
and
the State of Idaho Proposes to Certify the Permit
EPA Proposes NPDES Permit Reissuance
EPA proposes to reissue the existing National Pollutant Discharge Elimination System
(NPDES) permit to the Meridian Beartrack Company (MBC) Beartrack Mine. The draft permit
sets conditions on the discharge of pollutants from the Beartrack Mine to Napias Creek. In
order to ensure protection of water quality and human health, the permit places limits on the
types and amounts of pollutants that can be discharged.
This Fact Sheet includes:
information on public comment, public hearing, and appeal procedures
a description of the current and proposed discharges
a listing of proposed effluent limitations and other conditions
a map and description of the discharge locations
background information supporting the conditions in the draft permit
The State of Idaho Proposes Certification
The Idaho Division of Environmental Quality (IDEQ) proposes to certify the NPDES permit for
the Beartack Mine under section 401 of the Clean Water Act. The IDEQ did not submit a
preliminary 401 certification prior to the public notice.
Public Comments on the Draft Permit
Persons wishing to comment on or request a public hearing for the draft permit may do so in
writing by the expiration date of the public notice. A request for a public hearing must state the
nature of the issues to be raised, as they relate to the permit, as well as the requester's name,
address, and telephone number. All comment and requests for public hearings must be in
writing and submitted to EPA as described in the Public Comments section of the attached
public notice. After the public notice expires, and all substantive comments have been
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considered, EPA's regional Director for the Office of Water will make a final decision regarding
permit reissuance.
If no substantive comments are received, the tentative conditions in the draft permit will
become final, and the permit will become effective upon issuance. If comments are received,
EPA will address the comments and issue the permit. The permit will become effective 30
days after the issuance date, unless a request for an evidentiary hearing is submitted within 30
days.
Public Comment on the State Preliminary 401 Certification
The Idaho Division of Environmental Quality (IDEQ) provides the public with the opportunity to
review and comment on preliminary 401 certification decisions. Any person may request in
writing that IDEQ provide that person notice of IDEQ's preliminary 401 certification decision,
including, where appropriate, the draft certification. Persons wishing to comment on the
preliminary 401 certification should submit written comments by the public notice expiration
date to the Idaho Division of Environmental Quality (IDEQ), Idaho Falls Regional Office, 900
N. Skyline, Idaho Falls, ID 83402.
Documents are Available for Review
The draft NPDES permit and related documents can be reviewed or obtained by visiting or
contacting EPA's Regional Office in Seattle between 8:30 a.m. and 4:00 p.m., Monday through
Friday (see address below).
United States Environmental Protection Agency
Region 10
1200 Sixth Avenue, OW-130
Seattle, Washington 98101
(206) 553-0523 or
1-800-424-4372 (within Alaska, Idaho, Oregon, and Washington)
The fact sheet and draft permit are also available at:
EPA Idaho Operations Office
1435 North Orchard Street
Boise, Idaho 83706
(208) 378-5746
Idaho Division of Environmental Quality
Idaho Falls Regional Office
900 N. Skyline
Idaho Falls, Idaho 83402
(208) 528-2650
Salmon Public Library
204 Main Street
Salmon, Idaho 83467-4111
(208)756-2311
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The draft permit and fact sheet can also be found by visiting the Region 10 website at
http://www.epa.gov/r10earth.htm.
For technical questions regarding the permit or fact sheet, contact Kristine Koch at the phone
numbers or email address at the top of this fact sheet. Those with impaired hearing or speech
may contact a TDD operator at 1-800-833-6384 (ask to be connected to Kristine Koch at the
above phone numbers). Additional services can be made available to a person with disabilities
by contacting Kristine Koch.
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TABLE OF CONTENTS
LIST OF ACRONYMS 6
I. APPLICANT 8
II. FACILITY ACTIVITY 8
A. General 8
B. Mining Operations 9
C. Reclamation and Closure Operations 9
III. FACILITY BACKGROUND 10
A. Permit History 10
B. Compliance History 10
IV. RECEIVING WATER 11
A. Location of Discharge 11
B. Water Quality Standards 11
V. EFFLUENT LIMITATIONS 11
A. Basis for Permit Effluent Limits 11
B. Proposed Effluent Limitations 12
C. Antibacksliding 15
D. Analytical Methods 15
VI. MONITORING REQUIREMENTS 16
A. Basis for Effluent Monitoring 16
B. Basis for Whole Effluent Toxicity Monitoring 18
C. Basis for Surface Water Monitoring 18
D. Sample Type 20
E. Representative Sampling 20
VII. OTHER PERMIT CONDITIONS 21
A. Quality Assurance Plan 21
B. Best Management Practices Plan 21
C. Standard Permit Provisions 22
VIII. OTHER LEGAL REQUIREMENTS 22
A. Endangered Species Act 22
B. Essential Fish Habitat 22
C. National Environmental Policy Act 23
D. State Certification 23
E. Antidegradation 24
F. Permit Expiration 24
APPENDIX A-MERIDIAN BEARTRACK COMPANY (MBC) FACILITY MAPS
APPENDIX B - RECLAMATION AND CLOSURE ACTIVITIES
APPENDIX C - BEARTRACK MINE WASTE STREAMS
APPENDIX D - DEVELOPMENT OF EFFLUENT LIMITATIONS
APPENDIX E - ENDANGERED SPECIES ACT
APPENDIX F - ESSENTIAL FISH HABITAT
APPENDIX G - REFERENCES
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LIST OF TABLES
Table 1: Comparison of Current and Proposed Effluent Limitations for Outfall 001 12
Table 2: Comparison of Current and Proposed Effluent Monitoring Requirements for
Outfall 001 16
Table 3: Comparison of Current and Proposed Surface Water Monitoring Requirements ... 18
Table D-1: Technology-based Effluent Limitations Applicable to MBC Discharge D-3
Table D-2: Water Quality Criteria Applicable to Napias Creek D-6
Table D-3: Hardness-Based Water Quality Criteria Equations D-8
Table D-4: Temperature and pH Values for Ammonia Water Quality Criteria in Napias
Creek D-8
Table D-5: Site-Specific Translator Values for Napias Creek Below the Beartrack Mine's
Outfall 001 D-10
Table D-6: Default Translator Values for Napias Creek Below the Beartrack Mine's
Outfall 001 D-11
Table D-7: Summary of Effluent Statistics used to Determine Reasonable Potential D-13
Table D-8: Summary of Effluent Statistics used to Determine Reasonable Potential cont. D-14
Table D-9: Upstream Concentrations (Cu) used to Determine Reasonable Potential D-16
Table D-10: Upstream Receiving Water Flow Data for Napias Creek (1996-1999) D-18
Table D-11: Mixing Zone Dilutions for Outfall 001 D-19
Table D-12: Results of Reasonable Potential Analysis for Aquatic Life D-22
Table D-13: Results of Reasonable Potential Analysis for Human Heal and Agriculture . . D-23
Table D-14: Waste Load Allocations (WLAs) for Outfall 001 D-26
Table D-15: Long Term Averages (LTAs) for Outfall 001 D-28
Table D-16: Aquatic Life Effluent Limitations for Outfall 001 D-29
Table D-17: Human Health Effluent Limitations for Outfall 001 D-31
Table D-18: Agriculture Effluent Limitations for Outfall 001 D-32
Table D-19: Summary of Proposed Effluent Limitations for Outfall 001 D-36
Table E-1: Comparison of Hardness-Based Aquatic Life Criteria E-8
Table E-2: Comparison of Mixing Zone Dilutions for Hardness-Based Aquatic Life Criteria . E-9
Table E-3: Comparison of Reasonable Potential Analysis for Hardness-Based Aquatic
Life Criteria E-10
Table E-4: Comparison of Hardness-Based Effluent Limitations E-11
Table E-5: Comparison of Compliance Evaluation Levels E-12
LIST OF FIGURES
Figure A-1: Facility Location Map A-1
Figure A-2: General Mine Layout and Discharge Locations Map A-2
Figure A-3: Monitoring Site Location Map A-3
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LIST OF ACRONYMS
AHFR Average high flow rate
ALFR Average low flow rate
AML Average Monthly Limit
AWQC Ambient Water Quality Criteria
BADT Best Available Demonstrated Control Technology
BAT Best Available Technology Economically Achievable
BCT Best Conventional Pollutant Control Technology
BMP Best Management Practices
BO Biological Opinion
BPJ Best Professional Judgement
BPT Best Practicable Control Technology
CFR Code of Federal Regulations
cfs cubic feet per second
CV coefficient of variation
CWA Clean Water Act
DMR Discharge Monitoring Report
EFH Essential Fish Habitat
EPA Environmental Protection Agency
ESA Endangered Species Act
IDAPA Idaho Administrative Procedures Act
IDEQ Idaho Division of Environmental Quality
LTA Long-term Average
MBC Meridian Beartrack Company
MDL maximum daily limit
g/L micrograms per liter
mgd million gallons per day
MZ mixing zone
NMFS National Marine Fisheries Service
NPDES National Pollutant Discharge Elimination System
NSPS New Source Performance Standards
NTR National Toxics Rule
GAP
Quality Assurance Plan
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LIST OF ACRONYMS cont.
R Ratio ALFR to AHFR
RP Reasonable Potential
RPA Reasonable and Prudent Alternatives
RPM Reasonable Potential Multiplier
TSD Technical Support Document (EPA 1991)
TSS Total Suspended Solids
TU Toxic Unit (TUC = chronic toxic unit)
USFS Unites States Forest Service
USFWS United States Fish and Wildlife Service
WAD Weak Acid Dissociable
WET Whole Effluent Toxicity
WLA Wasteload Allocation
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APPLICANT
Meridian Beartrack Company
NPDES Permit No.: ID-002702-2
Mailing Address: P.O. Box 749
Salmon, Idaho 83467
Facility Location: See Part II.A and Figure A-1 in Appendix A
Facility Contact: Joe Woods, Site Manager
(208) 756-6300 ext. 3032
FACILITY ACTIVITY
A. General
The Beartrack Mine is an open pit, cyanide heap leach gold mine located
in east central Idaho, near the historic town of Leesburg in Lemhi County,
Idaho, within the Salmon National Forest (see Figure A-1). The mine is
currently owned and operated by the Meridian Beartrack Company
(MBC). Construction and operation of the mine began in 1994 and gold
production began in 1995 upon completion of the heap leach pad. The
Beartrack Mine has recently evolved from an operating mine to a mine
undergoing final gold recovery, reclamation and closure. The mine is
currently in the reclamation and closure phase. MBC has also ceased all
mining operations on March 22, 2000 and has ceased production of gold
from the heap leach on June 22, 2000.
The Beartrack Mine is located on private land, patented claims, and lands
administered by the United States Forest Service (USFS). The land
affected by the Beartrack Mine includes about 700 acres of the total 3,795
acres within the original project boundary defined in the Final Plan of
Operations (Meridian, 1991) and the Final Environmental Impact
Statement (USFS, 1991). Of the land affected by the Mine, approximately
77% is public land administered by the USFS.
The mine site involves two separate ore deposits that were mined by
open pit methods, a waste rock disposal site and heap leaching facilities
located near the pits. The two open pits, North and South, that were
originally constructed affect a total area of about 129 acres. A third
relatively small pit (less than ten acres), the Mason Dixon Pit, was
constructed in 1999. Other facilities include a process plant, process
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water ponds, sediment ponds, warehouse and maintenance building,
administration building, laboratory, and fuel storage tanks. The site
facilities are interconnected by haul roads, service roads, and the main
access route. Figure A-2 presents the general mine site layout.
Wastewater discharged from the mine will include storm water run-off and
heap leach rinsate. The wastewater is discharged through Outfall 001 to
Napias Creek. The storm water is treated at an onsite treatment plant
with flocculent to settle suspended particles.
B. Mining Operations
During mining operations, ore and waste rock were removed from the pits
in horizontal benches. An ammonium nitrate/fuel oil mixture is used to
blast ore out of one of two pits - the North Pit or the South Pit. The ore
was then moved via haul trucks to the process area while the waste rock
was transported to the waste rock disposal area. Waste rock (i.e.,
blasted rock containing too little ore to process) was placed in Wards
Gulch, 174 acres capable of holding 40 million tons of rock. Currently,
much of the site has either been reclaimed or is undergoing reclamation
under the direction of the USFS.
Gold was extracted from the ore deposits by cyanide heap leaching. The
ore was crushed, shaped, and placed in twenty-foot layers on the heap
leach pad. Solution made from sodium cyanide is spayed over the top of
the heap. The solution bonds with the gold in the ore, percolates through
the heap, and drains into catch basins. A processing plant pumped the
sodium cyanide gold-bearing solution from the catch basins to carbon
absorption tanks where the gold adheres to activated carbon. The gold
was recovered from the loaded carbon through zinc precipitation. The
"used" sodium cyanide was sent to a barren solution pond.
For use in the mining process, the Mine required the transportation of
toxic materials, including the following per month: 1,500 tons of quick
lime, 250 tons of antiscalent agent, 7.9 tons of hydrochloric acid, 6.6 tons
of caustic soda, and 175,000 gallons of fuel oil.
C. Reclamation and Closure Operations
The intent of the reclamation program is to reclaim mining related
disturbance, where conditions and current reclamation technology
reasonably permit, to protect public health, safety and welfare, conserve
natural resources, aid in the protection of wildlife, domestic animals and
aquatic resources and reduce soil erosion.
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The Idaho Department of Lands (IDL) is the primary state agency with
requirements for reclamation of surface mines (IDAPA 20.03.02). At the
onset of this project in 1990, MBC developed a Reclamation Plan in
accordance with the requirements of IDL. The general reclamation goal
at the Beartrack Project is to reclaim the site to allow essentially the same
land uses as existed prior to the project. Therefore, the reclamation plan
proposes to restore a tree-shrub-grassland vegetation type on most of the
site. The reclaimed landscape will also contain small areas of wetland
vegetation where topographic conditions, aspect, and drainage conditions
are conductive to establishment of these types of communities.
Reclamation activities have been scheduled to occur as soon as possible
after the mining activities in a particular area are completed to minimize
erosion and sedimentation problems. Therefore, MBC has been
undergoing reclamation of the Beartrack Mine in accordance with their
Reclamation Plan and subsequent amendments since 1998.
Reclamation activities include mine areas, waste rock disposal areas,
heap leach facilities, roads, diversions/sediment control structures,
ancillary facilities, and previously abandoned mine land. A brief
discussion and status of each of these activities is provided in
Appendix B.
FACILITY BACKGROUND
A. Permit History
EPA first issued a National Pollutant Discharge Elimination System
(NPDES) permit for the Beartrack Mine on September 30, 1991. The
current permit expired on October 30, 1996. A timely application for
renewal of the permit was submitted to EPA on April 29, 1996. The
renewal application included discharges from five outfalls, three existing
and two proposed. A Supplemental Information Report was submitted by
MBC in early May 2000 (received by EPA on May 8, 2000) to supplement
their permit application to reflect updated mining operations and water
management under the closure phase. Since the mine is now entering
the closure phase, only one outfall (Outfall 001, existing) will be required.
A description of the waste streams that contribute to the discharge is
provided in Appendix C. Because MBC submitted a timely application for
renewal, the 1991 permit has been administratively extended and remains
fully effective and enforceable until reissuance.
B. Compliance History
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MBC submits monthly discharge monitoring reports (DMRs) to EPA
summarizing the results of effluent monitoring required by the permit.
There were no effluent limit violations noted based on review of the past
five years' DMRs.
IV. RECEIVING WATER
A. Location of Discharge
The permittee has applied for the discharge of Outfall 001 to Napias
Creek. The Mine is located in the Napias Creek drainage approximately
7.5 miles upstream from its confluence with Panther Creek, and about 22
miles upstream from the confluence of Panther Creek and the main stem
Salmon River. The Mine is within the Middle Salmon-Panther Subbasin,
HUC 17060203 and part of the Panther Creek Watershed. The mine
affects approximately 740 acres of land in the Napias Creek drainage.
Tributary streams that contribute to Napias Creek include (going
downstream) Sawpit Creek, Smith Gulch, Sharkey Creek, Wards Gulch,
Camp Creek, Jefferson Creek, Arnett Creek, Rabbit Creek, Pony Creek,
Cat Creek, Missouri Gulch, Phelan Creek, Mackinaw Creek, and
Moccasin Creek.
B. Water Quality Standards
As discussed in Section A, the MBC outfall discharges to Napias Creek.
The Idaho Water Quality Standards and Wastewater Treatment
Requirements designate beneficial uses for waters of the State. This
water body is undesignated, therefore, it is classified by the state of Idaho
for protection of the following uses: (1) cold water biota, (2) salmonid
spawning, (3) secondary contact recreation, (4) agricultural water supply,
(5) industrial water supply, (6) wildlife habitats, and (7) aesthetics.
The State water quality standards specify water quality criteria that are
deemed necessary to support the use classifications. These criteria may
by numerical or narrative. The water quality criteria applicable to the
proposed permit are provided in Appendix D (Section III.B.). These
criteria provide the basis for most of the effluent limits in the draft permit.
V. EFFLUENT LIMITATIONS
A. Basis for Permit Effluent Limits
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In general, the Clean Water Act requires that the effluent limits for a
particular pollutant be the more stringent of either technology-based limits
or water quality-based limits. A technology-based effluent limit requires a
minimum level of treatment for point sources based on currently available
treatment technologies. A water quality-based effluent limit is designed to
ensure that the water quality standards of a water body are being met.
Appendix D provides discussion on the legal basis for the development of
technology-based and water quality-based effluent limits.
The information provided to EPA in the permit application process
indicates that the permittee may have difficulty meeting the proposed
effluent limitations for all the metals and may need to investigate means
to reduce the concentrations in their effluent prior to discharging to
Napias Creek.
B. Proposed Effluent Limitations
Table 1 summarizes the effluent limitations that are proposed in the draft
permit. For comparison purposes, the table also shows the effluent
limitations of the current permit. In addition to the limitations in Table 1,
the draft permit prohibits the permittee from discharging any floating
solids, visible foam in other than trace amounts, or oily wastes that
produce a sheen on the surface of the receiving water.
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Table 1: Comparison of Current and Proposed Effluent Limitations for Outfall 001
Parameter1
Ammonia
Arsenic
Cadmium
Chromium
Copper
Cyanide (WAD)
Iron
Lead
Units
mg/l
Ib/day
ug/l
Ib/day
ug/l
Ib/day
ug/l
Ib/day
ug/l
Ib/day
ug/l
Ib/day
mg/l
Ib/day
ug/l
Ib/day
Current Effluent Limitations
Average Monthly
5800
52.7
5.0
<0.05
1300
9.0
40
0.36
30.4
276
5.0
<0.05
Maximum
Daily
9500
86.3
9.0
0.08
2100
12.0
60
0.5
50.0
455
9.0
0.08
Proposed Effluent Limitations
Low Flow2
Average Monthly
7.8
20
1.4
0.0035
11
0.028
19
0.048
6.9
0.017
Maximum
Daily
6.6
58
1.3
0.011
12
0.11
18
0.16
6.8
0.060
High Flow3
Monthly Average
16
40
2.7
0.0068
21
0.053
37
0.093
14
0.035
Maximum
Daily
13
110
2.7
0.024
24
0.35
36
0.32
14
0.12
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Table 1: Comparison of Current and Proposed Effluent Limitations for Outfall 001
Parameter1
Mercury
PH
Selenium
Silver
TSS
Zinc
Footnotes:
Units
ug/l
Ib/day
su
ug/l
Ib/day
ug/l
Ib/day
mg/l
Ib/day
ug/l
Ib/day
Current Effluent Limitations
Average Monthly
0.4
<0.004
Maximum
Daily
0.6
<0.005
6.0 to 9.0
20
182
300
<2.7
30
273
500
4.5
Proposed Effluent Limitations
Low Flow2
Average Monthly
0.043
0.00011
Maximum
Daily
0.042
0.00037
within the range of 6.5 - 9.0
18
0.045
0.664
0.0017
20
50
75
0.19
17
0.15
0.744
0.0065
30
180
87
0.76
High Flow3
Monthly Average
0.086
0.00022
Maximum
Daily
0.084
0.00074
within the range of 6.5 - 9.0
36
0.090
1.3
0.0033
20
75
150
0.38
35
0.31
1.5
0.013
30
260
170
1.5
1 . Metals are to be measured as total recoverable, except for mercury which is to be measured as total.
2. The effluent limitations for the low flow period apply from July 1 through April 30.
3. The effluent limitations for the high flow period apply from May 1 through June 30.
4. This effluent limit is not quantifiable using EPA approved analytical methods. The permittee will be in compliance with the effluent limit
provided the measured concentration is at or below the compliance evaluation level of 1 .0 u/L using EPA Method 272.2.
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C. Antibacksliding
The proposed permit does not include effluent limitations for arsenic,
chromium, and iron, even though these parameters were limited in the
current permit. Section 402(o) of the Clean Water Act prohibits the
renewal, reissuance, or modification of an existing NPDES permit that
contains effluent limits, permit conditions, or standards that are less
stringent than those established in the previous permit. There are,
however, exceptions to the prohibition that allow the establishment of less
stringent limits.
The exception that applies to this circumstance is that new information is
available that was not available at the time of permit issuance which
would have justified a less stringent effluent limitation. At the time the
current permit was issued, the permittee was a "new discharger" and did
not have data on the proposed discharge because they had not
commenced operation. Therefore, the current permit was based on
expected effluent characteristics. Since the issuance of the current
permit, MBC has been sampling their discharge and the receiving water in
vicinity of their discharge. Hence, EPA had actual measured data to
evaluate the effects of the receiving water for the reissuance of this
permit. The measured data shows that effluent limitations are not
necessary for arsenic, chromium, and iron.
D. Analytical Methods
Some of the water quality-based effluent limits in the draft permit are
close to the capability of current analytical technology to detect and/or
quantify the concentration of that parameter. To address this concern,
the draft permit contains a provision requiring MBC to use analytical
methods that can quantify the effluent limitation. For parameters with
effluent limits that cannot be quantified (i.e., cadmium, copper, lead and
silver), the draft permit proposes that the compliance level with that limit is
the quantification level of the best analytical technology approved by EPA
in40CFR136.
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VI. MONITORING REQUIREMENTS
A. Basis for Effluent Monitoring
Section 308 of the Clean Water Act and federal regulation 40 CFR
122.44(i) require that monitoring be included in permits to determine
compliance with effluent limitations. Section 308 also allows additional
effluent monitoring to gather information for future effluent limitations or to
monitor effluent impacts on receiving water quality. MBC is responsible
for conducting the monitoring and reporting the results to EPA on monthly
DMRs and in annual reports. Table 2 presents the proposed effluent
monitoring requirements for the draft permit. For comparison purposes,
the table also includes the monitoring requirements of the current permit.
Monitoring frequencies are based on the nature and effect of the
pollutant, as well as a determination of the minimum sampling necessary
to adequately monitor the facility's performance. The monitoring
frequencies proposed in the draft permit are generally the same as those
in the current permit.
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Table 2: Comparison of Current and Proposed Effluent Monitoring Requirements
Parameter
Ammonia
Cyanide (WAD)
Flow
Metals
(Cd, Cu, Pb, Ni, Hg, Se, Ag, Zn)
Mass-based Limits
TSS
PH
Hardness, as CaCO3
Temperature
Chronic WET
Footnotes:
Current Permit
Units
mgd
ug/l
mg/l
su
NOEC
Sample Frequency
continuous
weekly
weekly
daily
twice per year1
Sample Type
recording
grab
grab
grab
grab
Draft Permit
Units
mg/l
ug/l
mgd
ug/l
Ib/day
mg/l
su
mg/l
°C
TUC
Sample Frequency
weekly
weekly
continuous
weekly
weekly
weekly
weekly
weekly
twice per year2
Sample Type
grab
grab
recording
grab
calculated
grab
grab
grab
grab
grab
1 . Test shall be performed in May and October for the first year of waste rock disposal operations, and again in May and October during the
12 months preceding the expiration date of the current permit.
2. Monitoring shall be performed in May and October.
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B. Basis for Whole Effluent Toxicity Monitoring
The draft permit requires whole effluent toxicity (WET) tests twice per
year during significant rainfall or snowmelt (i.e., May and October) to
measure the chronic toxicity of the discharge. Results of these tests will
be used to ensure that toxics in the effluent are controlled and to
determine the need for future WET limits. Monitoring and analyses of the
effluent for WET is warranted based on the prevalence of metals in the
discharge.
The draft permit establishes trigger levels that, if exceeded, would trigger
additional WET testing and/or an evaluation to reduce toxicity. The
trigger levels were calculated based on the chronic WET criterion of 1
TUc, the probability of acute toxic affects based on EPA's
recommendation of 0.3 TUa, and a dilution ratio of 25:1. The trigger
levels proposed in the draft permit are 17 TUc during the low flow period
and 16 TUc during the high flow period. These triggers were based on
calculations found in Chapters 1 and 5 of the TSD (see Section IV of
Appendix D for details).
C. Basis for Surface Water Monitoring
The purpose of surface water monitoring is to determine water quality
conditions as part of the effort to evaluate the reasonable potential for the
discharge to cause an instream excursion above water quality criteria.
Upstream monitoring is used to determine water quality impacts of the
NPDES discharge while downstream monitoring is used to ensure
compliance with the water quality standards. This data will be used
during the next permitting cycle to determine the need for incorporating
and retaining water quality-based effluent limits into the permit. Since the
purpose of surface water monitoring is to determine water quality impacts
due to the effluent discharge, surface water monitoring is required to
occur on the same date as effluent monitoring, to the extent possible.
The water quality monitoring requirements in the draft permit are, for the
most part, unchanged from the current permit. The draft permit requires
MBC to continue this monitoring as it relates to the permitted discharges
by specifying monitoring at selected locations upstream and downstream
of the discharge. Table 3 presents the proposed surface water monitoring
requirements for the draft permit. For comparison purposes, the table
also includes the monitoring requirements of the current permit.
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Table 3: Comparison of Current and Proposed Surface Water Monitoring Requirements
Parameter
Ammonia
Cyanide (WAD)
Floating Solids or Visible Foam
Flow
Metals
(Cd, Cu, Pb, Hg, Ni, Se, Ag, Zn)
TSS
PH
Hardness, as CaCO3
Temperature
Current Permit
Units
ug/L
cfs
ug/L
mg/L
s.u.
Sample Frequency
weekly
daily
2/month
2/month
2/month
Sample Type
grab
measurement
grab
grab
grab
Draft Permit
Units
mg/L
ug/L
cfs
ug/L
mg/L
s.u.
mg/L
°C
Sample Frequency
2/month
2/month
2/month
daily
2/month
2/month
2/month
2/month
2/month
Sample Type
grab
grab
visual
measurement
grab
grab
grab
grab
grab
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D. Sample Type
The following sample types are proposed in the draft permit:
1. Visual. The only way to adequately measure a discharge for
floating solids, foam, and oily sheens is to conduct a visual
analysis of the receiving waterbody to determine the presence or
absence.
2. Grab. Grab samples are appropriate for parameters (e.g., pH and
cyanide) that are likely to change with storage or for parameters
(e.g., TSS) that are not likely to change over time. For this
discharge, grab sampling for WET is more appropriate because the
probability of peak toxicity occurring in a short duration.
3. Calculated. Since effluents are analyzed for concentrations, it is
appropriate to calculate the loadings for parameters (e.g., TSS and
metals) by multiplying the measured concentration by the flow and
a conversion factor to ensure the appropriate units are reported.
For example, a concentration in mg/L is converted to a loading of
Ib/day by multiplying the concentration by the flow in mgd and a
conversion factor of 8.34.
4. Continuous. Since the discharge is dependent upon precipitation,
continuous monitoring of effluent flow is necessary to determine
how the effluent flow varies in relation to the receiving water flow.
E. Representative Sampling
The draft permit has expanded the requirement in the federal regulations
regarding representative sampling (40 CFR 122.410]). This provision now
specifically requires representative sampling whenever a bypass, spill, or
non-routine discharge of pollutants occurs, if the discharge may
reasonably be expected to cause or contribute to a violation of an effluent
limit under the permit. This provision is included in the draft permit
because routine monitoring could miss permit violations and/or water
quality standards exceedences that could result from bypasses, spills, or
non-routine discharges. This requirement directs MBC to conduct
additional, targeted monitoring to quantify the effects of these
occurrences on the final effluent discharge.
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VII. OTHER PERMIT CONDITIONS
A. Quality Assurance Plan
Federal regulations at 40 CFR 122.41(e) require permittees to properly
operate and maintain their facilities, including "adequate laboratory
controls and appropriate quality assurance procedures." To implement
this requirement, the current permit required MBC to submit a Quality
Assurance Plan (QAP) within 90 days of the effective date of the permit
(October 30, 1996). The most recent version of this plan is entitled
meridian Gold Company - Beartrack Mine, Water Quality Monitoring,
Quality Control and Quality Assurance Program, Revision II, January
1997.
The EPA Region 10 Quality Assurance (QA) Unit has reviewed MBC's
QAP for the Beartrack Mine and has found several shortcomings. The
draft permit requires that MBC modify their Quality Assurance Plan (QAP)
to address the shortcomings identified by the QA Unit to ensure that the
monitoring data submitted is accurate.
The draft permit requires MBC to submit the modified QAP to EPA within
60 days of the effective date of the permit and implement the QAP within
120 days of the effective date.
B. Best Management Practices Plan
Section 402 of the Clean Water Act and federal regulations at 40 CFR
122.44(k)(2) and (3) authorize EPA to require best management practices
(BMPs) in NPDES permits. BMPs are measures that are intended to
prevent or minimize the generation and the potential for release of
pollutants from industrial facilities to waters of the U.S. These measures
are important tools for waste minimization and pollution prevention.
The draft permit requires MBC to prepare and implement a BMP Plan
within 180 days of permit issuance. The BMP Plan is intended to achieve
the following objectives: minimize the quantity of pollutants discharged
from the facility, reduce the toxicity of discharges to the extent practicable,
prevent the entry of pollutants into waste streams, and minimize storm
water contamination. The BMP Plan will apply to all components of the
Beartrack Mine. The draft permit requires that the BMP Plan be
maintained and that any modifications to the facility are made with
consideration to the effect the modification could have on the generation
or potential release of pollutants. The BMP Plan must be revised if the
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facility is modified and as new pollution prevention practices are
developed.
The draft permit also requires comprehensive site compliance evaluations
documenting the compliance evaluations, observations related to
implementation of the BMP Plan, any incidents of non-compliance, and
any corrective actions and BMP Plan modifications over the year.
C. Standard Permit Provisions
In addition to facility-specific requirements, most of sections II, IV, and V
of the draft permit contain "boilerplate" requirements. Boilerplate is
standard regulatory language that applies to all permittees and must be
included in NPDES permits. Because the boilerplate requirements are
based on regulations, they cannot be challenged in the context of an
NPDES permit action. The boilerplate covers requirements such as
monitoring, recording, reporting requirements, compliance
responsibilities, and general requirements.
VIM. OTHER LEGAL REQUIREMENTS
A. Endangered Species Act
The Endangered Species Act (ESA) requires federal agencies to consult
with the National Marine Fisheries Service and the U.S. Fish and Wildlife
Service (collectively referred to as the Services) if their actions could
beneficially or adversely affect any threatened or endangered species.
The Services have identified several threatened and endangered species
in the vicinity of the Beartrack Mine discharge. Appendix E provides
further information on the listed species.
EPA is currently undergoing informal consultation with the NMFS and
USFWS. As part of the consultation, EPA is preparing a Biological
Evaluation (BE) to evaluate the potential impacts of the NPDES discharge
on the endangered and threatened species. If the consultation results in
reasonable and prudent alternatives or measures that require more
stringent permit conditions, EPA will incorporate those conditions into the
final permit.
B. Essential Fish Habitat
Essential fish habitat (EFH) is the waters and substrate (sediments, etc.)
necessary for fish to spawn, breed, feed, or grow to maturity. The
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Magnuson-Stevens Fishery Conservation and Management Act (January
21, 1999) requires EPA to consult with the National Marine Fisheries
Service (NMFS) when a proposed discharge has the potential to
adversely affect (reduce quality and/or quantity of) EFH. An assessment
of EFH is provided in Appendix F. The EPA has tentatively determined
that the issuance of this permit will not affect any EFH species in the
vicinity of the discharge, therefore no consultation is required. This fact
sheet and the draft permit will be submitted to NMFS for review during the
public notice period. Any recommendations received from NMFS
regarding EFH will be considered prior to final issuance of this permit.
C. National Environmental Policy Act
In compliance with EPA headquarter policy guidance for reissued NPDES
permits to new source dishcargers, the EPA Region 10 National
Environmental Policy Act (NEPA) Compliance Program has assessed the
need to re-evaluate the NEPA analysis in regard to the reissuance of the
proposed NPDES permit to MBC for the Beartrack Mine. Since the
proposed permit conditions are equal to or more stringent that the current
NPDES permit and there have not been, nor are there going to be, any
proposed changes to any other aspects of the applicant's operations,
EPA does not consider the proposed NPDES permit to constitute a
significant change warranting the need to undertake a new NEPA
analysis. Therefore, EPA Region 10 has determined that the previous
Environmental Impact Statement developed in June 1991 does not need
to be amended with a new NEPA analysis. The finding of no significant
impact from the NEPA analysis in the Final Environmental Impact
Statement developed in June 1991 is incorporated here by reference.
D. State Certification
Section 401 of the Clean Water Act requires EPA to seek certification
from the State that the permit is adequate to meet State water quality
standards before issuing a final permit. The regulations allow for the
state to stipulate more stringent conditions in the permit, if the certification
cites the Clean Water Act or State law references upon which that
condition is based. In addition, the regulations require a certification to
include statements of the extent to which each condition of the permit can
be made less stringent without violating the requirements of State law.
The state of Idaho did not provide EPA with a preliminary certification of
this permit.
After the public comment period, a proposed final permit will be sent to
IDEQ for final certification. If IDEQ authorizes different requirements in its
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final certification, EPA will incorporate those requirements into the permit.
For example, if the State authorizes different mixing zones in its final
certification, EPA will recalculate the effluent limitations in the final permit
based on the dilution available in the final mixing zones.
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E. Antidegradation
In setting permit limitations, EPA must consider the State's
antidegradation policy. This policy is designed to protect existing water
quality when the existing quality is better than that required to meet the
standard and to prevent water quality from being degraded below the
standard when existing quality just meets the standard. For high quality
waters, antidegradation requires that the State find that allowing lower
water quality is necessary to accommodate important economic or social
development before any degradation is authorized. This means that, if
water quality is better than necessary to meet the water quality standards,
increased permit limits can be authorized only if they do not cause
degradation or if the State makes the determination that it is necessary.
The current permit has effluent limitations for arsenic, chromium and iron
for outfall 001. Since the reasonable potential analysis indicated no
reasonable potential to cause or contribute to an exceedence of water
quality criteria, limits for arsenic, chromium, and iron were not included in
the draft permit.
Because the effluent limits in the draft permit are based on current water
quality criteria or technology-based limits that have been shown to not
cause or contribute to an exceedence of water quality standards the
discharges as authorized in the draft permit will not result in degradation
of the receiving water. Therefore, the conditions in the permit will comply
with the State's antidegradation requirements.
F. Permit Expiration
This permit will expire five years from the effective date of the permit.
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APPENDIX A - MERIDIAN BEARTRACK COMPANY (MBC) FACILITY MAP
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APPENDIX B - RECLAMATION AND CLOSURE ACTIVITIES
As a supplement to Section II of the Fact Sheet, this appendix describes reclamation
and closure activities at the Beartrack Mine. This section is broken into the following
seven phases of reclamation proposed by MBC: mine areas (Section I), waste rock
disposal areas (Section II), heap leach facilities (Section III), roads (Section IV),
diversions and sediment control structures (Section V), ancillary facilities (Section VI),
and abandoned mine lands (Section VII). Each section provides a brief description of
the reclamation activities, the activities that have been completed, the activities that are
to be completed during the term of the proposed permit, and the activities that will be
completed beyond the term of the proposed permit.
I. Mine Areas
A. Reclamation Activities
The mine areas are to be reclaimed to create a safe and stable
topographic feature which can be used by livestock and wildlife. The
North Pit and Mason/Dixon Pit will be reclaimed into a mixture of
wetlands, meadow, cliffs, and talus slopes, all surrounded by a dense
pine and fir forest. However, the South Pit will be reclaimed to a lake.
Reclamation of the North Pit and Mason/Dixon Pit include the following
activities: sculpting of highwalls to create an irregular cliff or bluff-type
landscape suitable for raptor nesting; sculpting, molding, backfilling, and
over-vegetation of benches to create a stable land form, precipitation and
snowmelt drainage area, and visual continuity; coversoil and revegetation
of the pit floor to create a meadow for enhanced livestock grazing;
revegetating the edge of the access/haul roads with shrubs and grasses
to create a corridor and cover for wildlife and livestock ingress and
egress; and creation of a wetland in the southern portion of the pit floor to
provide wetland functions including sediment stabilization, nutrient
retention and wildlife habitat.
The following activities are included in the reclamation of the South Pit:
accelerated fill of the pit until the water level reaches equilibrium with the
bedrock aquifer to create a lake suitable for livestock and wildlife
watering, and potentially a fishery depending on the water quality;
creation of cover areas and revegetation of the edge of the pit lake;
sculpting of highwalls to create an irregular cliff or bluff-type landscape
suitable for raptor nesting; and sculpting, molding, backfilling, and over-
vegetation of remaining exposed benches to create a stable land form,
precipitation and snowmelt drainage area, and visual continuity.
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B. Completed Reclamation Activities
Reclamation activities that have occurred thus far include:
North Pit: Approximately 70% of the North pit has been backfilled.
Mason/Dixon Pit: Sculpting, backfilling, and seeding.
South Pit: Partial fill of the pit.
C. Current Reclamation Activities
Reclamation activities that will take place during the effective period of
the proposed NPDES permit include:
North Pit: Finish backfilling, capping and revegitation.
Mason/Dixon Pit: Ensure adequate vegetation growth for sediment
stability.
South Pit: Construct treatment wetlands and finish rapid fill of the pit.
D. Future Reclamation Activities
Future reclamation activities include:
North Pit: Ensure adequate vegetation growth for sediment stability.
South Pit: Ensure water level reaches equilibrium with the bedrock
aquifer to create a lake suitable for livestock and wildlife watering;
determine whether or not the water quality will support a fishery; ensure
effectiveness of treatment wetlands; create cover areas and revegetate
the edge of the pit lake; sculpt highwalls to create an irregular cliff or
bluff-type landscape; and sculpt, mold, backfill, and over-vegetate
remaining exposed benches to create a stable land form, precipitation
and snowmelt drainage area, and visual continuity.
Waste Rock Disposal Areas
A. Reclamation Activities
The waste rock disposal area will be reclaimed to blend into the
surrounding topography to the extent practical. The waste rock dump will
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be constructed from the head of the valley in a downslope direction by
conventional truck haul/end methods. The active face of the dump will be
regraded to achieve an overall slope of 3:1. The crest of the disposal
areas will be rounded where practical, and drainages will be maintained
on either side of the area. Intermediate waste dump benches will be
graded to drain to the back and out each side of the disposal area to the
drainages. The uppermost surface of the dump will be sloped to the back
into the side of the hill to prevent runoff and erosion over the face. The
benches and top of the disposal area will be covered with soil and
revegetated.
B. Completed Reclamation Activities
Reclamation activities that have occurred thus far include approximately
50% of the grading.
C. Current Reclamation Activities
Reclamation activities that will take place during the effective period of
the proposed NPDES permit include completion of grading, soil covering,
and revegetation.
D. Future Reclamation Activities
Future reclamation activities include ensuring adequate vegetation growth
for sediment stability and effectiveness of drainages.
Heap Leach Facilities
A. Reclamation Activities
The heap leach facilities include the heap, the processing pond and the
ditch connecting the heap to the processing pond. The reclamation of
this area is broken into the following phases: heap rinsing, heap grading
and cover, solution pond reclamation, and ditch reclamation.
The purpose of rinsing the heap is to remove the cyanide that was used
during the gold recovery process during mining operations. The rinsing
process begins by spraying water over the heap. Then the rinse water
will discharge at the toe of the heap, travel through the existing collection
ditch to the existing solution ponds. Finally, the rinse water from the
solution ponds will either be managed by reusing for further rinsing or by
discharging to Outfall 001. Rinsing of the heap will be accomplished by
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natural precipitation and snowmelt, using fresh water, or using treated
water from the solution ponds. The heap will be rinsed until the WAD
cyanide concentrations in the recovery water from the heap reach a
concentration of 0.2 mg/L.
Once the rinsing phase is complete, the heap will be graded to eliminate
the bench slopes and create more natural contours. The surface of the
heap will result in a minimum of 1 percent grade and the side slopes of
the heap will be reduced to a maximum 3:1 grade. After heap grading is
completed, it will be covered with a layer of soil, a layer of vegetative
material, another layer of soil, and then seeded for vegetative growth.
The performance of the cover will be monitored for approximately two
years to ensure that discharge from the reclaimed heap will not degrade
the water quality of Napias Creek based on Idaho's water quality
standards. During this time, the discharge at the toe of the heap will
travel through the existing collection ditch to the solution ponds.
After the rinse solution monitoring program indicates compliance with the
cover performance criteria, the solution ponds will be reclaimed. This
phase includes folding the liners into the pond areas and grading the
pond embankments to cover the liners and to provide shallow
depressions to facilitate development of wetlands. These wetlands will be
fed by the collection ditch that carries the discharge from the toe of the
heap and runoff from the heap. The water quality in the wetlands will be
monitored to determine potential adverse impacts from the heap
discharge after closure. The wetland monitoring program will last for up
to three months following wetland construction.
At the completion of the pond reclamation and monitoring, the solution
collection ditch will be reclaimed and reconstructed to become an
infiltration ditch. The infiltration ditch will provide a more natural transport
of seepage emerging from the toe of the heap to pass into the wetland
area. It is anticipated that most of the heap seepage will infiltrate, with
measurable flow to the wetland occurring only during snowmelt or storm
events.
B. Completed Reclamation Activities
Reclamation activities that have occurred thus far include heap rinsing
and grading.
C. Current Reclamation Activities
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Reclamation activities that will take place during the effective period of
the proposed NPDES permit include further rinsing and contouring of the
heap, capping and seeding the heap, and construction of the treatment
wetlands.
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D. Future Reclamation Activities
Future reclamation activities include ensuring adequate vegetation growth
for sediment stability and monitoring to determine effectiveness of
treatment wetlands.
IV. Roads
A. Reclamation Activities
Haul or access roads abandoned during the operating life of the project or
at closure will be reclaimed unless the USFS requests that they remain
open. Road surfaces at grade will be ripped to reduce compaction and
coversoiled in preparation for seeding. As required by the Idaho
Administrative Code (IDAPA 20.03.02), abandoned roads will be cross-
ditched as necessary to control erosion. Sections of roads through cuts
and fills will be stabilized using construction erosion control features,
such as diversion ditches, terraces or water bars, and vegetated with
approved plant species. Sediment control structures will be maintained
until reclamation efforts are completed and no longer needed. The
sediment control structures will then be removed or reclaimed. Surface
water-holding features will be broken up or removed and the affected area
will be backfilled to grade and stabilized through vegetation.
B. Completed Reclamation Activities
No reclamation activities that have occurred thus far.
C. Current Reclamation Activities
It is not anticipated that these reclamation activities that will take place
during the effective period of the proposed NPDES permit.
D. Future Reclamation Activities
Future reclamation activities include appropriate closure procedures
unless the USFS requests that the roads remain open.
V. Diversions/Sediment Control Structures
A. Reclamation Activities
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Following reclamation of the mine site and facilities, the sediment
structures will be decommissioned. Depending upon the post mining land
use, the structures may be either cleaned out and removed and the area
reclaimed, or left in-place as surface water impoundment for livestock and
wildlife use. When the structures are removed, the sediment will be used
in reclamation or buried within the waste rock dumps.
Additionally, stream diversion channels or ditches that are no longer
necessary will be reclaimed. Channels will be re-established as close as
possible to the pre-mining drainage pattern with similar channels,
aspects, and longitudinal profiles. Temporary diversions constructed
around the waste rock dump will be evaluated to determine whether these
diversions should be upgraded to permanent diversions or rerouted along
the groin of the dumps. The final drainage channel route will be
evaluated to determine channel velocities, erosion potential, necessary
vegetation, and other construction elements to ensure the channels are
stable and are not contributing sediment to downstream areas.
B. Completed Reclamation Activities
No reclamation activities that have occurred thus far.
C. Current Reclamation Activities
It is not anticipated that these reclamation activities that will take place
during the effective period of the proposed NPDES permit.
D. Future Reclamation Activities
Future reclamation activities depends upon the post mining land use.
The structures may be either cleaned out and removed and the area
reclaimed, or left in-place as surface water impoundment for livestock and
wildlife use.
VI. Ancillary Facilities
A. Reclamation Activities
Plant facilities, ancillary facilities, and all equipment on site will be
decommissioned and removed or salvaged, if possible. The building
foundations will be buried and the building facility site will be graded to
establish drainage and fill in depressions. Surfaces will be loosened,
covered with soil, and seeded for vegetation. Monitoring wells will be
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plugged and abandoned according the Idaho State water well
requirements.
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B. Completed Reclamation Activities
No reclamation activities that have occurred thus far.
C. Current Reclamation Activities
Reclamation activities that will take place during the effective period of
the proposed NPDES permit include removal of all buildings and
equipment.
D. Future Reclamation Activities
Future reclamation activities include burring building foundations; grading
the building facility site; cover the site with soil; and seed for vegetation.
Monitoring wells will be plugged and abandoned according the Idaho
State water well requirements.
VII. Abandoned Mine Land Reclamation
A. Reclamation Activities
The area of the mine project is located in historic Mackinaw or Leesburg
Mining District. This area has been extensively placered and hydraulicly
mined leaving behind many acres of unreclaimed placer gravels,
diversion ditches and borrow sites. Approximately 18 acres of previously
mined land will be reclaimed by MBC. These areas include placers
covered by the Wards Gulch waste dump and sedimentation pond, placer
gravels in the Wards Gulch and Camp Creek construction laydown areas,
placers utilized as an aggregate source along Napias Creek, and placer
gravels reclaimed as a result of disposal of excess cut material generated
during wetland mitigation at Phelan Creek.
B. Completed Reclamation Activities
These reclamation activities that have been completed.
C. Current Reclamation Activities
No reclamation activities will take place during the effective period of the
proposed NPDES permit.
D. Future Reclamation Activities
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No future reclamation activities will occur.
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APPENDIX C - BEARTRACK MINE WASTE STREAMS
As a supplement to Section III of the Fact Sheet, this appendix describes wastewater
management and discharges from the Beartrack Mine. This section includes: a
description of each of the waste streams discharged or proposed to be discharged from
the facility through Outfall 001 (Section I); and discussions for the removal of existing
and previously proposed outfalls (Section II). A map of the discharge location(s) is
provided in Appendix A (Figure A-2).
I. Continuance of Permitted Outfall 001
The current NPDES permit authorizes discharge to Napias Creek from Outfall
001 in accordance with specified effluent limitations and monitoring
requirements. Outfall 001 is located immediately below the confluence with
Arnett Creek. It was constructed and became operational in 1995. The design
of Outfall 001 incorporates a multi-port diffuser to maximize initial dilution.
Pollutants of concern in Outfall 001 include metals (arsenic, cadmium,
chromium, copper, iron, lead, manganese, mercury, nickel, silver, and zinc),
weak acid dissociable (WAD) cyanide, ammonia, nitrate, total suspended solids
(TSS), and pH.
A. Storm Water
During closure operations, the water management strategy will focus on
erosion control and management of mine related waters either through
the NPDES system or by transferring storm water to accelerate South Pit
filling. Waters discharged through Outfall 001 will be managed through
the existing storm water system and will include runoff from both disturbed
and reclaimed portions of roads and mine facilities, as well as other
various disturbances. Contributing flows are projected to include surface
water runoff and springs and seeps from the Wards Gulch waste rock
facility and french drain, North Pit, administrative area, crusher-conveyor
areas, refinery area, and haulage and service roads.
The storm water treatment plant, used forflocculation of suspended
particles, will be utilized to treat storm water prior to discharge through
Outfall 001. Depending upon water management needs, the pretreatment
system for pit dewatering and for North Pit backfill construction will remain
operational, as long as needed, into closure. As mine facilities, roads,
and other disturbed areas are reclaimed and become revegetated, use of
the storm water treatment plant should begin to decline. It is anticipated
that the plant will be dismantled at the end of the closure period.
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B. South Pit
The South Pit is not expected to discharge during this permit cycle,
however, it is an important component of water management during mine
closure. During closure, the South Pit will naturally begin filling to form a
lake as documented in the FEIS (USFS, 1991). The mine is the routing
project surface water into the South Pit to accelerate filling. The mine
began use of this option in Spring of 2001 based on a hydrochemical
model of the South Pit (Shepherd Miller, Inc., 2000) that predicted
accelerated filling reduced the length of time that mineralized rock in the
pit shell is exposed to oxygen results in predictions of pit water chemistry
that have substantially improved water quality. The model estimated that
it would take five years to fill the pit using the accelerated filling scenario.
C. Heap Leach Pad
Several options are being considered for managing neutralized water
from the leach pad. These options include: containing all neutralized
water within the facility, transferring neutralized water to accelerate South
Pit filling, enhanced evaporation, treatment and discharge, and land
application. Since it may prove most feasible to manage neutralized
water during closure through a combination of management activities, the
mine has requested that the re-issued permit allow for the discharge of
neutralized water from the leach pad through Outfall 001.
Heap leach operations for extracting gold and silver included the
application of dilute sodium cyanide solutions to the ore. Thererfore, the
chemistry of the neutralized solution removed from the leach pad during
closure may include low concentrations of WAD cyanide and nitrogenous
products resulting from cyanide degradation (e.g., nitrate and ammonia).
Removal of Existing and Proposed Outfalls
A. Outfall 002
In the 1996 renewal application, MBC proposed to discharge through
Outfall 002 to Smith Gulch, which is a tributary to Napias Creek. Outfall
002 was intended to discharge storm water and snow melt runoff, Ward's
Gulch By-pass, and water from various springs and seeps. However, the
permittee never discharged from this outfall. Since 1996, the water
management strategy for the Beartrack mine has been modified to reflect
closure operations; therefore, Outfall 002 will not be required and MBC
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has modified their application (MBC, 2000) to remove this proposed
outfall from the renewal application.
B. Outfall 003
The existing NPDES permit authorizes discharge from Outfall 003 to an
unnamed tributary (ephemeral drainage) of Napias Creek. This outfall
was constructed in 1995 to discharge water from natural springs and
seeps beneath the lined heap leach pad. In 1997, MBC observed an
intermittent trickle from Outfall 003 and collected samples. During a
subsequent field inspection, EPA staff indicated that the observed
conditions at Outfall 003 did not constitute a discharge to waters of the
U.S. During more recent discussions between MBC and EPA, EPA staff
have indicated that the discharge from this outfall to waters of the U.S. is
not likely to occur because the construction of the mine, specifically the
heap leach pad, altered the pre-existing terrain that provided drainage to
the unnamed tributary of Napias Creek. Since there is no water flow in
the unnamed tributary, there is no way for the discharge to reach Napias
Creek. Therefore, EPA recommended that MBC remove Outfall 003 from
their permit application. MBC has since modified their permit application
(MBC, 2000) to remove this outfall from the renewal application. In the
event that water from beneath the leach pad needs to be collected and
discharged, it will be done so through Outfall 001.
C. Outfall 003B
In the 1996 renewal application, MBC proposed to discharge through
Outfall 003B to an unnamed gulch that is a tributary to Napias Creek.
Outfall 003B was intended to discharge water from various springs and
seeps. Since 1996, the water management strategy for the Beartrack
mine has been modified to reflect closure operations; therefore, Outfall
003B will not be required and MBC has modified their application (MBC,
2000) to remove this proposed outfall from the renewal application.
D. Outfall 004
The existing NPDES permit authorizes discharge from Outfall 004 to an
unnamed tributary (ephemeral drainage) of Napias Creek. This outfall
was intended to discharge water from natural springs and seeps beneath
the lined heap leach pad. However, this outfall was not ever constructed
because the portion of the heap leach pad that corresponded to this
outfall was never built. MBC has since modified their permit application
(MBC, 2000) to remove this outfall from the renewal application.
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APPENDIX D - DEVELOPMENT OF EFFLUENT LIMITATIONS
This appendix discusses the basis for and the development of the proposed effluent
limits in the draft permit. This section includes: an overall discussion of the statutory
and regulatory basis for development of effluent limitations (Section I); discussions of
the development of technology-based effluent limits (Section II) and water quality-
based effluent limits (Section III); an evaluation of whole effluent toxicity (WET)
(Section IV); and a summary of the effluent limits proposed for this draft permit
(Section V).
I. Statutory and Regulatory Basis for Limits
Sections 101, 301 (b), 304, 308, 401, 402, and 405 of the Clean Water Act (CWA)
provide the basis for the effluent limitations and other conditions in the draft permit.
The EPA evaluates the discharges with respect to these sections of the CWA and the
relevant National Pollutant Discharge Elimination System (NPDES) regulations under
40 CFR Part 122 to determine which conditions to include in the draft permit.
In general, the EPA first determines the necessary effluent limits based on the
technology available to treat the effluent (i.e., technology-based limits). EPA then
evaluates the effluent quality expected to result from the treatment technology to
determine whether effluent limits are necessary to protect the designated uses of the
receiving water (i.e., water quality-based limits). The proposed permit limits will reflect
whichever requirements (technology-based or water quality-based) are more stringent.
II. Technology-based Evaluation
A. Overview.
There are two general approaches for developing technology-based
effluent limits for industrial facilities: (1) using national effluent limitations
guidelines (ELGs) and (2) using Best Professional Judgment (BPJ) on a
case-by-case basis. The intent of a technology-based effluent limitation
is to require a minimum level of treatment for industrial point sources
based on currently available treatment technologies while allowing the
discharger to use any available control technique to meet the limitations.
The national ELGs are developed based on the demonstrated
performance of a reasonable level of treatment that is within the economic
means of specific categories of industrial facilities. Where national ELGs
have not been developed or did not consider specific pollutant
parameters in discharges, the same performance-based approach is
applied to a specific industrial facility based on the permit writer's BPJ. In
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some cases, technology-based effluent limits based on ELGs and BPJ
may be included in a single permit.
B. National Effluent Limitation Guidelines.
Section 301 (b) of the CWA requires technology-based controls on
effluents. This section of the CWA requires that, by March 31, 1989, all
permits contain effluent limitations which: (1) control toxic pollutants and
nonconventional pollutants through the use of "best available technology
economically achievable" (BAT), and (2) represent "best conventional
pollutant control technology" (BCT) for conventional pollutants by March
31, 1989. In no case may BCT or BAT be less stringent than "best
practical control technology currently achievable" (BPT), which is the
minimum level of control required by section 301(b)(1)(A) of the CWA.
In addition to BPT and BAT requirements, section 306 of the CWA
established more restrictive requirements for "new sources." The intent of
this special set of guidelines is to set limitations that represent state-of-
the-art treatment technology for new sources because these dischargers
have the opportunity to install the latest in treatment technology at the
time of start-up. These standards, identified as new source performance
standards (NSPS), are described as the best available demonstrated
control technology (BADT), processes, operating methods, or other
alternatives including, where practicable, standards permitting no
discharge of pollutants. NSPSs are effective on the date of the
commencement of a new facility's operation and the facility must
demonstrate compliance within 90 days (40 CFR 122.29(d)).
For several specific industrial sectors, EPA has developed effluent
limitation guidelines (ELGs) that contain BPT, BCT, BAT, and NSPS
limitations. On December 3, 1982, EPA published effluent guidelines for
the mining industry. These guidelines are found in 40 CFR Part 440.
Effluent guidelines applicable to gold mines, such as the Beartrack Mine,
are found in the Copper, Lead, Zinc, Gold, Silver, and Molybdenum Ores
Subcategory (Subpart J) of Part 440. The BADT(40 CFR 440.104)
effluent limitation guidelines that apply to gold mine discharges are shown
in Table D-1. However, these effluent limitations only apply to a mine with
an "active mining area" as defined in 40 CFR 440.132(a). Since the
Beartrack Mine no longer meets the definition of an active mining area,
these effluent limitations do not apply to their discharge.
Nevertheless, EPA is applying these effluent limitations as Region 10's
best professional judgement (BPJ) determination of Best Practicable
Control Technology Currently Available (BPT) controls for this discharge.
D-2
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BPT is based on the average of the best existing performance by plants of
various sizes, ages, and unit processes within the industrial category or
subcategory. BPJ-based effluent limits are technology-based limits
derived on a case-by-case basis under Section 402(a)(1) of the Clean
Water Act. BPJ limits are established in cases where ELGs are not
available for, or do not regulate, a particular pollutant of concern. EPA
has developed this BPJ effluent limitation in accordance with federal
regulations 40 CFR 125.3.
Table D-1 : Technology-Based Effluent Limitations Applicable to
MBC Discharge
Effluent Characteristic
cadmium, ug/l
copper, ug/l
lead, ug/l
mercury, ug/l
zinc, ug/l
TSS, mg/l
pH, su
Footnotes:
Effluent Limitations1
daily maximum
100
300
600
2
1,500
30
monthly average
50
150
300
1
750
20
within the range 6.0 -9.0
1 . Effluent limitations for metals are expressed as total recoverable metal.
Water Quality-based Evaluation
A. Overview
In addition to the technology-based limits discussed above, EPA
evaluated the MBC's discharges to determine compliance with Section
301 (b)(1 )(C) of the CWA. This section requires the establishment of
limitations in permits necessary to meet water quality standards by July 1,
1977.
The regulations at 40 CFR 122.44(d) implement section 301 (b)(1 )(C) of
the CWA. These regulations require that permits include limits for all
pollutants or parameters which "are or may be discharged at a level which
will cause, have the reasonable potential to cause, or contribute to an
D-3
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excursion above any state water quality standard, including state
narrative criteria for water quality." The limits must be stringent enough to
ensure that water quality standards are met, and must be consistent with
any available wasteload allocation (WLA).
In determining whether water quality-based limits are needed and
developing those limits when necessary, EPA follows guidance in the
Technical Support Document for Water Quality-based Toxics Control
(TSD; EPA, 1 991 ). The water quality-based analysis consists of four
steps:
1 . Determine the appropriate water quality criteria (Section III.B);
2. Determine if there is "reasonable potential" for the discharge to
exceed the criteria in the receiving water (Section III.C.);
3. If there is "reasonable potential", develop a WLA (see Section
4. Develop effluent limitations based on the WLA (see Section
III.D.2).
The following sections provide a detailed discussion of each step.
B. Water Quality Criteria
The first step in developing water quality-based limits is to determine the
applicable water quality criteria. For Idaho, the State water quality
standards are found at IDAPA 58, Title 1 , Chapter 2 (IDAPA 58.01 .02).
The applicable criteria are determined based on the beneficial uses of the
receiving water. As discussed in Section IV of this fact sheet, the
beneficial uses for the receiving waters of the Beartrack Mine discharge
are as follows:
N a pi as Creek (outfall 001) - cold water biota, salmonid
spawning, and secondary contact recreation (IDAPA
58.01. 02. 101. 01. a), agricultural and industrial water supply
(IDAPA 58.01.02.100.03), wildlife habitats (IDAPA
58.01.02.100.04), and aesthetics (IDAPA 58.01.02.100.05).
For any given pollutant, different uses may have different criteria. To
protect all beneficial uses, the permit limits are based on the most
stringent of the water quality criteria applicable to those uses. The
applicable criteria based on the above uses are summarized in Tables D-
2 through D-4.
D-4
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Idaho's aquatic life criteria for several of the metals of concern are
calculated as a function of hardness measured in mg/l of calcium
carbonate (CaC03). The hardness-based water quality criterion
equations are provided in Table D-3. As the hardness of the receiving
water increases, the toxicity of these metals decreases and the numerical
value of the criteria increases.
The Idaho water quality standards (IDAPA 58.01.02.210.01) incorporates
the toxic criteria set forth in 40 CFR 131.36(b)(1) (National Toxics Rule),
as of July 1, 1993, which specifies a hardness range of 25-400 mg/L.
Therefore, the hardness generally used to calculate the criteria is the
hardness in the receiving water after mixing with the effluent (i.e.,
downstream hardness). For Outfall 001, the fifth percentile of actual
hardness measurements downstream of the outfall were 6 mg/L during
low flow and 4 mg/L during high flow. Since the measured hardness falls
below the low end cap for the criteria, a hardness of 25 mg/L was used to
develop these criteria.
In addition to the calculation for hardness, Idaho's criteria for some metals
include a "conversion factor" to convert from total recoverable to
dissolved criteria. Conversion factors address the relationship between
the total amount of metal in the water column (i.e., total recoverable
metal) and the fraction of that metal that causes toxicity (i.e., bioavailable
metal or dissolved fraction). Conversion factors for the dissolved criteria
are shown in Table D-3.
The Idaho water quality standards have differing temperature
requirements that apply to Napias Creek. For the designated use of cold
water aquatic life, water temperatures are to exhibit 22°C or less with a
maximum daily discharge of no greater than 19°C at all times. However,
for the designated use of salmonid spawning, water temperatures are to
exhibit 13°C or less with a maximum daily average no greater than 9°C.
Salmonid spawning periods are as follows: August 1 through April 1 for
chinook salmon (spring), August 15 through June 15 for Chinook salmon
(summer), October 1 through June 1 for sockeye salmon, and February 1
through July 15 for Steelhead. Additionally, the designated use of bull
trout requires water temperatures to exhibit an average daily maximum
temperature of 10°C over a 7-day period from June through September.
D-5
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Table D-2: Water Quality Criteria Applicable to Napias Creek1
Parameter,
( g/L, unless
otherwise noted)
Ammonia6
(mg/L)
Arsenic
Cadmium
Chromium III
Chromium VI
Copper
Iron
Lead
Manganese
Mercury
Nitrate
Nickel
pH (s.u.)
Selenium
Silver
Cold Water Biota - Aquatic Life Criteria2
Acute Criteria
low flow4 high flow5
11 6.0
360
0.82
180
16
4.6
NA
14
NA
2.1
Chronic Criteria
low flow4 high flow5
2.2 1.9
190
0.37
57
11
3.5
NA
0.54
NA
0.012
Human Health Criteria
Secondary Contact Recreation
Criteria (consumption of organisms)3
NA
50
NA
NA
NA
NA
NA
NA
NA
0.15
Agriculture Water Supply
Criteria
Livestock
Watering
NA
200
50
1,000
1,000
500
NA
100
NA
10
Irrigation
NA
100
10
100
100
200
5,000
5,000
200
NA
surface waters shall be free from excess nutrients that can cause visible slime growths or other nuisance aquatic growths
that impair designated beneficial uses
440
49
within the range of 6.5 - 9.5
20
0.32
5
NA
4600
NA
NA
NA
NA
NA
50
NA
200
NA
20
NA
D-6
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Table D-2: Water Quality Criteria Applicable to Napias Creek1
Parameter,
( g/L, unless
otherwise noted)
Temperature
(°C)
Turbidity (NTU)
WAD Cyanide
WET (TU)
Zinc
Footnotes:
Cold Water Biota - Aquatic Life Criteria2
Acute
low flow4
Criteria Chronic Criteria
high flow5 low flow4
high flow5
9 13
below mixing zone, shall not exceed
background turbidity by more than 50 NTU
instantaneously or more than 25 NTU for more
than 10 days
22 5
.2
Human Health Criteria
Secondary Contact Recreation
Criteria (consumption of organisms)3
NA
NA
220,000
Agriculture Water Supply
Criteria
Livestock
Watering
NA
NA
NA
Irrigation
NA
NA
NA
surface waters shall be free from toxic substances in concentrations that impair designated beneficial uses7
35 32
NA
25,000
2,000
1 . Per IDAPA 58.01 .02.252.02, water quality criteria for agricultural and industrial water supplies, wildlife habitat, and aesthetics will generally be satisfied
by the water quality criteria set forth in Section 200 of the Idaho water quality standards (surface waters shall be free from toxic substances in
concentrations that impair designated beneficial uses).
2. The aquatic life criteria are based on IDAPA 58.01.02.210. This section cites the National Toxics Rule (NTR), 40 CFR 131.36(b)(1), and the NTR
subparts for toxics (metals and cyanide). The aquatic life criteria for arsenic, cadmium, chromium, copper, lead, mercury (acute only), nickel, silver, and
zinc are expressed as the dissolved fraction of the metal. The aquatic life criteria for cadmium, chromium III, copper, lead, nickel, silver, and zinc are
calculated as a function of hardness per the equations shown in Table D-3. The hardness value used in the criteria equations was 25 mg/L.
3. The recreation criteria are based on IDAPA 58. 01. 02. 210. 01. b, which cites the NTR (except for arsenic which is specified as 50 ug/l in the Idaho
standards).
4. The low flow period is July 1 through April 30.
5. The high flow period is May 1 through June 30.
6. The ammonia criteria was based on temperature and pH, which were derived from the criteria for temperature and the 95th percentile of instream pH
data. The temperature and pH values used to determine the appropriate criteria are provided in Table D-4
7. EPA's recommended magnitudes for this narrative criterion are 1 TUcand 0.3 TUa for the chronic and acute criteria, respectively (TSD 1991). TU means
toxicity units, where TUC is equal to the reciprocal of the effluent concentration that causes no observable effect in a chronic toxicity test and TUa is the
reciprocal of the effluent concentration that causes 50% mortality in an acute toxicity test.
D-7
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Table D-3: Hardness-Based Water Quality Criteria Equations
Parameter
Cadmium
Chromium III
Copper
Lead
Nickel
Silver
Zinc
acute
chronic
acute
chronic
acute
chronic
acute
chronic
acute
chronic
acute
acute
chronic
dissolved criterion = conversion factor x total criterion
(H = hardness)
conversion factor
1.1 36672- [0.041 838Hn(H)]
1. 101672 - [0.041 838Hn(H)]
0.316
0.86
0.960
0.960
1.46203 -[0.1 4571 2Hn(H)]
1.46203 -[0.1 4571 2Hn(H)]
0.998
0.997
0.85
0.978
0.986
total criterion
exp [1.128Hn(H)- 3.828]
exp [0.7852Hn(H) - 3.490]
exp [0.81 8Hn(H) + 3.688]
exp[0.818-ln(H) + 1.561]
exp [0.9422Hn(H) - 1 .464]
exp [0.8545Hn(H) -1 .465]
exp [1 .273Hn(H) - 1 .460]
exp [1 .273Hn(H) - 4.705]
exp[0.846Hn(H) + 3.3612]
exp [0.846Hn(H) + 1.1645]
exp [1 .72Hn(H) - 6.52]
exp [0.8473Hn(H) + 0.8604]
exp[0.8473-ln(H) + 0.7614]
Table D- 4: Temperature and pH Values for Ammonia Water Quality Criteria in Napias Creek
Parameter
Temperature (°C)3
pH (s.u.)
Footnotes:
Acute Criterion
low flow1
9
7.6
high flow2
9
8.0
Chronic Criterion
low flow
13
7.5
high flow
13
7.8
1 . The low flow period is July 1 through April 30.
2. The high flow period is May 1 through June 30.
3. The temperature is based on the criteria for salmonid spawning.
C. Reasonable Potential Evaluation
1. Procedure for Determination of Reasonable Potential
To determine if there is "reasonable potential" to cause or
contribute to an exceedence of water quality criteria for a given
pollutant (and therefore whether a water quality-based effluent limit
D-8
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is needed), for each pollutant present in a discharge, EPA
compares the maximum projected receiving water concentration to
the criteria for that pollutant. If the projected receiving water
concentration exceeds the criteria, there is "reasonable potential",
and a limit must be included in the permit. EPA uses the
recommendations in Chapter 3 of the TSD to conduct this
"reasonable potential" analysis. This section discusses how
reasonable potential is evaluated.
The maximum projected receiving water concentration is
determined using the following mass balance equation.
Cd x Qd = (Ce x Qe) + (Cu x Qu) (Equation 1)
where,
Cd = receiving water concentration downstream of the
effluent discharge (concentration at the edge of the
mixing zone)
Ce = maximum projected effluent concentration
Cu = receiving water upstream concentration
Qe = effluent flow
Qu = receiving water upstream flow
Qd = receiving water flow downstream of the effluent
discharge = (Qe + Qu)
If a mixing zone is allowed and solving for Cd, the mass balance
equation becomes :
Cd = rCXCL + C, (Q, MZ}] (Equation 2)
[Q. + (Qu MZ)]
where, MZ is the fraction of dilution in the mixing zone based on
receiving water flow.
Where no mixing zone is allowed,
Cd = Ce. (Equation 3)
By regulation (40 CFR 122.45(c)), the permit limit, in most
instances, must be expressed as total recoverable metal. Because
chemical differences between the discharged effluent and the
receiving water are expected to result in changes in the partitioning
between dissolved and adsorbed forms of metal, an additional
calculation using what is called a translator is required.
D-9
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Translators can either be site-specific numbers or default numbers.
EPA guidance related to the use of translators in NPDES permits is
found in The Metals Translator: Guidance for Calculating a Total
Recoverable Permit Limit from a Dissolved Criterion (EPA 823-B-
96-007, June 1996). In the absence of site-specific translators,
this guidance recommends the use of the water quality criteria
conversion factors (Table D-3) as the default translators. However,
MBC has conducted a study to develop site-specific translator
values for Napias Creek. This study provided empirically derived
translators for arsenic, copper, iron, lead, manganese, nickel, and
zinc. The values for the site-specific translators are provided in
Table D-5.
Table D-5: Site-Specific Translator Values for Napias Creek
Below the Beartrack Mine's Outfall 001
Parameter
Arsenic
Copper
Lead
Nickel
Zinc
Site-Specific Translator Value
Acute
0.67
0.77
0.28
0.77
0.83
Chronic
0.67
0.77
0.28
0.77
0.83
Because site-specific translators were not derived for all
parameters of concern, the conversion factors for cadmium,
chromium, and silver were used as default translators in the
reasonable potential and permit calculations for the TCMC
discharges. The values for these default translators are provided
in Table D-6.
D-10
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Table D-6: Default Translator Values for Napias Creek
Below the Beartrack Mine's Outfall 001
Parameter
Cadmium
Chromium III
Mercury
Silver
Footnotes:
Default Translator Value1
Acute
1.00
0.316
0.85
0.85
Chronic
0.97
0.86
NA
NA
1 . These values, except mercury, are based on the conversion factors in
Table D-3 using a hardness of 25 mg/L.
Therefore, for those metals with criteria expressed as dissolved,
Equations 2 and 3 become:
where a mixing zone is allowed:
' translator) CL + C, (Q, MZ)1.
[Q. + (Qu MZ)]
and where no mixing zone is allowed:
CH = (X translator.
(Equation 4)
(Equation 5)
After Cd is determined, it is compared to the applicable water
quality criterion. If it is greater than the criterion, a water quality-
based effluent limit is developed for that parameter. The following
discusses each of the factors used in the mass balance equation to
calculate Cd.
2. Maximum Projected Effluent Concentration (Ce)
For parameters with technology-based effluent limits (cadmium,
copper, lead, mercury, and zinc), the daily maximum limit was used
as the maximum projected receiving water concentration (Ce). The
technology-based effluent limit is used in this manner because
water quality-based effluent limits are only required when the
discharge at the technology-based limit has the reasonable
potential to violate water quality standards. The TSD procedure
was used for all other parameters.
D-11
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Per the TSD, the maximum projected effluent concentration in the
mass balance equation is represented by the 99th percentile of the
effluent data. The 99th percentile is calculated using the statistical
approach recommended in the TSD:
Ce = MEC x RPM (Equation 6)
where,
MEC = maximum measured effluent concentration
RPM = reasonable potential multiplier.
The RPM accounts for uncertainty in the effluent data. The RPM
depends upon the amount of effluent data and variability of the
data as measured by the coefficient of variation (CV) of the data.
The RPM decreases as the number of data points increases and
the variability (CV) of the data decreases. When there are not
enough data to reliably determine a CV (less than 10 data points),
the TSD recommends using 0.6 as a default value. Once the CV of
the data is determined, the RPM is determined using the statistical
methodology discussed in Section 3.3 of the TSD. If all the data
was below detect, EPA assumed a RPM of 1.0.
The effluent statistics used in the reasonable potential calculations
were based on data collected by MBC (DMR data and other
monitoring) and EPA (compliance inspection data) from 1997
through 2000. Only these four years of data were used since it
was determined to be most representative of current and future
conditions. A summary of the data statistics used in the
reasonable potential analysis is provided in Tables D-7 and D-8.
D-12
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Table D-7: Summary of Effluent Statistics used to Determine Reasonable Potential
Parameter
Ammonia3
Arsenic
Cadmium4
Chromium4
Copper4
Cyanide (WAD)3
Iron
Lead4
Manganese
Mercury4
Nickel4
Selenium3
Silver4
Zinc4
Footnote:
Units
mg/l
g/l
g/l
g/l
g/l
g/l
g/l
g/l
g/l
g/l
g/l
ug/l
g/l
g/l
Standard
Deviation (s)
low
flow1
36.3
575
89
high
flow2
62.2
1,342
210
Mean ( )
low
flow1
89.0
914
241
high
flow2
98.1
1,370
508
Coefficient of
Variation (CV)
low
flow1
0.6
0.4
0.6
0.6
0.6
0.6
0.6
0.6
0.4
0.6
0.6
0.6
0.6
0.6
high
flow2
0.6
0.6
0.6
0.6
0.6
0.6
1.0
0.6
0.4
0.6
0.6
0.6
0.6
0.6
Popular Variance
(2)=ln(CV2+1)
low
flow1
0.31
0.15
0.31
0.31
0.31
0.31
0.33
0.31
0.13
0.31
0.31
0.31
0.31
0.31
high
flow2
0.31
0.31
0.31
0.31
0.31
0.31
0.67
0.31
0.16
0.31
0.31
0.31
0.31
0.31
Standard Deviation
(')
low
flow1
0.55
0.39
0.55
0.55
0.55
0.55
0.58
0.55
0.36
0.55
0.39
0.55
0.34
0.55
high
flow2
0.55
0.55
0.55
0.55
0.55
0.55
0.82
0.55
0.40
0.55
0.53
0.55
0.34
0.55
# Data Points (n)
low
flow1
0
78
78
76
78
0
76
79
76
85
78
0
78
76
high
flow2
0
27
27
27
26
0
27
27
26
28
27
1
27
27
1. The low flow period is July 1 through April 30.
2. The high flow period is May 1 through June 30.
3. There was little or no data for these parameters, however, reasonable potential was established based on the permit application. The applicant has
requested that the permit allow the discharge of heap leach rinsate, which was not authorized under the previous permit. A CV of 0.6 is assumed for the
purposes of statistical analysis.
4. Most or all the data points for this pollutant were below detection using the analytical method specified in the previous permit, therefore, a CV of 0.6 is
assumed for the purposes of statistical analysis.
D-13
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Table D-8: Summary of Effluent Statistics used to Determine Reasonable Potential cont.
Parameter
Ammonia3
Arsenic
Cadmium4
Chromium4
Copper4
Cyanide (WAD)3
Iron
Lead4
Manganese
Mercury4
Nickel4
Selenium3
Silver4
Zinc4
Units
mg/l
g/i
g/i
g/i
g/i
g/i
g/i
g/i
g/i
g/i
g/i
ug/l
g/i
g/i
Percentile
p(n)=(1-0.99)(1/n)
low
flow1
0.9427
0.9427
0.9427
0.9427
0.9412
0.9434
0.9412
0.9412
0.9427
0.9427
0.9412
high
flow2
...
0.8432
0.8432
0.8432
0.8377
0.8432
0.8432
0.8377
0.8377
0.8432
0.8432
0.8432
z-score (z)
low
flow1
...
1.578
1.578
1.578
1.578
1.565
1.584
1.565
1.619
1.578
1.578
1.565
high
flow2
...
1.008
1.008
1.008
0.985
1.008
1.008
0.985
1.029
1.008
1.008
1.008
RPM
RPM=exp[2.326- -0.5- 2]/[exp[z- -0.5- 2]
low flow1
1.3
1.0
1.5
1.0
1.6
1.5
1.3
1.5
1.5
1.5
1.5
high flow2
...
2.1
1.0
2.1
1.0
2.9
2.1
1.7
2.1
2.1
1.0
2.1
2.0
MEC
low
flow1
200
5
20
10
2,300
20
370
1.0
50
10
410
high
flow2
...
200
5
20
30
3,670
20
780
0.3
60
6.3
10
120
Ce
(RPM) x (MEC)
low
flow1
270
1005
30
3005
3,570
6005
490
25
80
15
1,500=
high
flow2
...
430
1005
42
3005
10,800
6005
1,300
25
130
6.3
21
1,500=
D-14
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Table D-8: Summary of Effluent Statistics used to Determine Reasonable Potential cont.
Footnote:
1. The low flow period is July 1 through April 30.
2. The high flow period is May 1 through June 30.
3. There was little or no data for these parameters, however, reasonable potential was established based on the permit application. The applicant has requested
that the permit allow the discharge of heap leach rinsate, which was not authorized under the previous permit. A CV of 0.6 is assumed for the purposes of
statistical analysis.
Most or all the data points for this pollutant were below detection using the analytical method specified in the previous permit, therefore, a CV of 0.6 is assumed
for the purposes of statistical analysis.
Technology-based limit from Table D-1.
D-15
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3. Upstream Receiving Water Concentration (Cu)
The upstream receiving water concentration in the mass balance
equation is based on a reasonable worst-case estimate of the
pollutant concentration upstream from the discharge point. Where
sufficient data exists, the 95th percent!le of the receiving water data
is generally used as an estimate of worst-case.
MBC has been monitoring the receiving waters since the beginning
of mine operations. EPA used the receiving water data collected
by MBC at Station WQ-22 from 1997 through 2000 to calculate Cu.
Two difficulties were encountered in evaluating the receiving water
data. First, much of the data was reported as non-detect and in
some cases the detection limits exceeded the water quality criteria.
Second, much of the non-detect data had more than one detection
level. Therefore, EPA made the following assumptions:
where all or most of the data were non-detect (<10 detected
values), zero was assumed; and
where all or most of the data were detected (>10 detected
values), the 95th percentile of the detected values was
assumed.
The upstream receiving water concentrations (Cu) derived for each
parameter are identified in Table D-9 (see Figure A-3 for
monitoring station location).
D-16
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Table D-9: Upstream Concentrations (Cu) used to Determine Reasonable Potential
Parameter
Ammonia
Arsenic
Cadmium
Chromium
Copper
Cyanide (WAD)
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Turbidity
Zinc
Units
mg/l
g/l
g/i
g/l
g/i
g/l
g/i
g/i
g/i
g/i
g/i
ug/i
g/i
NTU
g/i
Dissolved Concentration
low flow
0
0
0
0
0
0
0
20
0
0
high flow
0
0
0
0
0
0
0
10
0
0
Total Concentration
low flow
0.14
0
0
0
0
3,520
0
70
0
30
0
59
0
high flow
0.35
0
0
0
0
1,310
0
20
0
5
0
17
0
4. Upstream Flow (Qu)
The upstream flow used in the mass balance equation depends
upon the criterion that is being evaluated. In accordance with the
applicable federal and state regulations and the TSD guidance, the
critical low flows used to evaluate compliance with the water quality
criteria are:
The 1 -day, 10-year low flow (1Q10) is used for the
protection of aquatic life from acute effects. It represents
the lowest daily flow that is expected to occur once in 10
years.
The 7-day, 10-year low flow (7Q10) is used for protection of
aquatic life from chronic effects. It represents the lowest 7-
day average flow expected to occur once in 10 years.
D-17
-------
The 30-day, 5-year low flow (30Q5) is used for the
protection of human health and agricultural uses from non-
carcinogens. It represents the 30-day average flow
expected to occur once in 5 years.
The harmonic mean flow is a long-term average flow and is
used for the protection of human health and agricultural
uses from carcinogens. It is the number of daily flow
measurements divided by the sum of the reciprocals of the
flows.
Data collected from United States Geological Survey (USGS)
station on Napias Creek were used to estimate the critical low
flows applicable to outfall 001. The USGS has been monitoring the
daily flow of Napias Creek at Station No. 13306385 since August
1991. The USGS has made these data available through
September 2000, which equates to just over nine years of daily
flow data.
The location of the Napias Creek USGS station is approximately
ten feet below Outfall 001 and 30 feet below the confluence of
Napias Creek and Arnett Creek. Since the gaging station flow is
below the outfall, the data must be corrected to provide the
upstream flow by subtracting out the effluent flow rate. EPA was
only able to do this from 1996 through 1999 because these were
the only years that EPA had daily effluent flow values. This does
not provide an adequate amount of flow data to calculate the 1Q10
and 7Q10 low flows, which require a minimum of ten years of daily
records. To remedy this, given that there are 4 years of corrected
upstream flow data, the minimum low flow value, and the minimum
low flow value for the seven-day running average, will be
substituted for the 1Q10 and the 7Q10 low flows, respectively.
However, these flows will continue to be referred to in this fact
sheet as the 1Q10 and 7Q10 low flows to eliminate confusion.
Napias Creek flows vary dramatically with precipitation and snow
melt, with peak flows occurring from May through June. Therefore,
the reasonable potential analysis for these outfalls was conducted
for both the high and low flow conditions and two sets of effluent
limits were developed for Outfall 001 which corresponded to both
flow conditions. Flows representative of critical flow conditions are
provided in Table D-10. Since effluent limitations are based on a
monthly basis, the low flow period values in Table D-10 are from
D-18
-------
July 1 through April 30 and the high flow period values in Table D-
10 are from May 1 through June 30 even though the true high flow
period extends into the month of July.
D-19
-------
Table D-10: Upstream Receiving Water Flow Data for Napias Creek
(1996-1999)
Critical Low Flow
1Q10, mgd
7Q10, mgd
30Q5, mgd
harmonic mean, mgd
Flow Values
low flow
(July 1 - April 30)
3.05
4.01
4.66
6.65
high flow
(May 1 - June 30)
12.39
13.74
43.88
53.55
5. Mixing Zone (MZ)
Mixing zones are defined as a limited area or volume of water
where the discharge plume is progressively diluted by the receiving
water. Water quality criteria may be exceeded in the mixing zone
as long as acutely toxic conditions are prevented from occurring
and the applicable existing designated uses of the water body are
not impaired as a result of the mixing zone. Mixing zones are
allowed at the discretion of the State, based on the State water
quality standards regulations.
The Idaho water quality standards at IDAPA 58.01.02.060 allow for
the use of mixing zones after a biological, chemical, and physical
appraisal of the receiving water and the discharge. The standards
allow water quality within a mixing zone to exceed chronic water
quality criteria so long as chronic water quality criteria are met at
the boundary of the mixing zone. Acute water quality criteria may
be exceeded within a zone of initial dilution inside the chronic
mixing zone.
In accordance with state water quality standards, only IDEQ may
authorize mixing zones. As discussed in Section VIII.D of the Fact
Sheet, IDEQ has not prepared a preliminary CWA Section 401
Certification authorizing mixing zones for the Beartrack Mine
discharges. The mixing zone volumes that may be authorized by
IDEQ are shown in Table D-11. More information on the mixing
zones (including the biological, chemical, and physical appraisal)
will be available in IDEQ's final certification.
D-20
-------
If IDEQ authorizes a different size mixing zone in its final 401
certification, EPA will recalculate the reasonable potential and
effluent limits based on the final mixing zones. If the State does
not authorize a mixing zone in its 401 certification, EPA will
recalculate the limits based on meeting water quality criteria at the
point of discharge (i.e., "end-of-pipe" limits).
Table D-1 1 : Mixing Zone Dilutions for Outfall 001
(expressed as percent of receiving water flow)
Parameter
Ammonia
Arsenic
Cadmium
Chromium
Copper
Cyanide, WAD
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Zinc
Footnote:
Aquatic Life
low flow
25
O2
25
O2
25
25
25
25
25
25
25
25
high flow
25
25
25
O2
25
25
25
25
25
25
25
Human Health/Agriculture1
low flow
25
75
O2
25
O2
O2
50
25
100
O2
100
O2
high flow
25
25
O2
25
O2
25
25
25
25
O2
100
O2
1 . The Idaho standards are silent regarding mixing zones for human health criteria. EPA used up to
100% of the receiving water for dilution for human health criteria, since the mixing zone size
limitation for aquatic life is to account for fish passage.
2. A mixing zone was not necessary for this parameter because reasonable potential was not
determined when no dilution was used in the calculations.
D-21
-------
6. Effluent Flow (Qe)
The effluent flow used in the mass balance equation is the
maximum effluent flow. Because the receiving water exhibits
dramatic seasonal variations, separate effluent flows were
determined for both high and low receiving water flows to allow
accurate analysis of receiving water effects. Additionally, MBC is
diverting flow that would normally discharge through Outfall 001 to
the South Pit to accelerate filling during closure. MBC estimates
that approximately 72 million gallons per year will be diverted to
the South Pit. Therefore, MBC has stated that the maximum
effluent flow for the low flow period (July 1 through April 30) and
the high flow period (May 1 through June 30) are 0.471 cfs
(0.30 mgd) and 1.62 cfs (1.05 mgd), respectively.
7. Reasonable Potential Analysis Results
Results of the reasonable potential analysis for each parameter is
provided in Tables D-12 and D-13. Based on the reasonable
potential analysis, water quality-based effluent limits were
developed for the following parameters: arsenic, ammonia,
cadmium, copper, cyanide (WAD), lead, mercury, selenium, silver,
and zinc.
D-22
-------
Table D-12: Results of Reasonable Potential Analysis for Aquatic Life
Parameter
Ammonia
Arsenic
Cadmium
Chromium
Copper
Cyanide (WAD)
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Turbidity
Zinc
Units
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
NTU
ug/L
Projected Downstream Concentration
(Cd)
acute
low flow
N/A
179
28
9.6
65
N/A
47
0.5
16
N/A
3.6
0.4
352
high flow
N/A
70
25
13
58
N/A
43
0.22
24
N/A
4.5
0.5
315
chronic
low flow
N/A
179
22
26
53
N/A
39
0.46
13
N/A
0.4
287
high flow
N/A
65
23
36
54
N/A
39
0.23
22
N/A
0.5
292
Reasonable Potential
(y/n)
low flow
y
n
y
n
y
y
n
y
n
y
n
y
y
n
y
high flow
y
n
y
n
y
y
n
y
n
y
n
y
y
n
y
Notes
RP determined because cyanide from heap rinsate in
discharge will increase ammonia concentration
RP determined because of potential discharge from
heap during shutdown operations
RP determined because of potential discharge from
heap during shutdown operations
net increase less than 50 NTU for acute and 25 NTU for
chronic
means no criterion
N/A means not able to determine CH using Equations 4 or 5.
D-23
-------
Table D-13: Results of Reasonable Potential Analysis for Human Health and Agriculture
Parameter
Ammonia
Arsenic
Cadmium
Chromium
Copper
Cyanide (WAD)
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Turbidity
Zinc
Units
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
NTU
ug/L
Projected Downstream
Concentration (Cd)
Human Health
Agriculture
low flow
41
8
30
61
N/A
3,600
68
155
0.12
76
N/A
1500
high flow
30
9
42
26
N/A
2,100
52
116
0.09
125
N/A
1500
Reasonable Potential
(y/n)
low flow
n
n
n
n
n
n
n
n
n
n
n
y
n
n
n
high flow
n
n
n
n
n
n
n
n
n
n
n
y
n
n
n
Notes
RP determined because of potential discharge from
heap during shutdown operations
means no criterion
N/A means not able to determine Cri using Equations 4 or 5.
D-24
-------
D. Derivation of Water Quality-based Effluent Limits
1. Development of Wasteload Allocations (WLAs)
Once EPA has determined that a water quality-based effluent limit
is required for a pollutant, the first step in deriving the effluent limit
is development of a wasteload allocation (WLA) for the pollutant.
A WLA is the concentration (or loading) of a pollutant that the
permittee may discharge without causing or contributing to an
exceedence of water quality standards in the receiving water.
WLAs and permit limits are derived based on guidance in the TSD
(EPA, 1991). WLAs for this permit were established in two ways:
based on a mixing zone (for most metals) and based on meeting
water quality criteria at "end-of-pipe" (for pH).
WLAs are calculated for each parameter based on each criterion.
Where the state authorizes a mixing zone for the discharge, the
WLA is calculated as a mass balance, based on the available
dilution, background concentration of the pollutant, and the water
quality criterion. It should be noted that there may be different
mixing zones for different parameters or even for criterion. WLAs
are calculated using the same mass balance equation used in the
reasonable potential evaluation (see Equation 1) although, Cd
becomes the criterion and Ce the WLA. Making these
substitutions, Equation 1 is rearranged to solve for the WLA (or
Ce), becoming:
WLA = Ce = [criterion (CL + (Q, MZ)1 - fC.. (Q, MZ)1 (Equation 7).
Qe
The values for Cu, Qu, MZ, and Qe are the same as those used in
the reasonable potential analysis (see Section III.C). For criteria
expressed as dissolved, the translator is added to Equation 7 and
the WLA is calculated as:
WLA = Ce = [(criterion * translator) *(Q. + (Q,, *MZ))1 - [C,, (Q,, *MZ)1 (Equation
8).
Qe
The translator values are provided in Tables D-5 and D-6. Where
no mixing zone is allowed, the criterion becomes the WLA (see
Equation 9) or the dissolved metal criterion using a translator
becomes the WLA (see Equation 10). Establishing the criterion as
D-25
-------
the WLA ensures that the permittee does not contribute to an
exceedence of the criteria.
WLA = criterion (Equation 9)
WLA = criterion - translator (Equation 10)
The WLAs for the parameters that exhibited reasonable potential
(see Tables D-12 and D-13 for results of reasonable potential
analysis) are provided in Table D-14.
D-26
-------
Table D-14: Waste Load Allocations (WLAs) for Outfall 001
Parameter
Ammonia
Cadmium
Copper
Cyanide (WAD)
Lead
Mercury
Selenium
Silver
Zinc
Units
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Aquatic Life
acute
low flow
40
2.9
21
78
175
8.5
71
1.3
151
high flow
23
3.2
24
87
196
9.5
79
1.5
168
chronic
low flow
9.6
1.7
20
23
8.4
0.052
22
169
high flow
8.1
1.6
19
22
8.3
0.051
21
166
Human Health
Secondary Contact
Recreation
low flow
high flow
Agriculture
Livestock
low flow
826
high flow
2,140
Irrigation
low flow
331
high flow
856
D-27
-------
Since the different criteria (acute aquatic life, chronic aquatic life,
human health, agriculture) apply over different time frames and
may have different mixing zones, it is not possible to compare the
criteria, or the WLAs developed from the criteria, directly to
determine which criterion results in the most stringent limits. For
comparison between aquatic life criteria, human health criteria, and
agricultural criteria, effluent limits must be derived for each, and
the most stringent effluent limits applied to the discharge.
Because many criteria for protection of aquatic life have two
criteria, acute and chronic, the effluent limits for each requirement
yields different effluent treatment requirements that cannot be
compared to each other without calculating the long-term average
performance level the facility would need to maintain in order to
meet each requirement. Therefore, EPA develops effluent limits
for aquatic life protection by statistically converting the WLAs to
long-term average (LTA) concentrations and using the most
stringent LTA to develop effluent limitations for protection of
aquatic life. This procedure will allow the facility to design a
treatment system for one level of effluent toxicity - the most limiting
toxic effect.
2. Calculation of Long-term Average Concentrations (LTAs) for
Aquatic Life Criteria
The conversion of a WLA to a LTA is dependent upon the
coefficient of variation (CV) of existing effluent data and the
selected probability distribution of the effluent. The probability
distribution corresponds to the percentile of the estimated effluent
concentration. EPA uses a 99th percentile probability distribution
for calculating a long-term average, as recommended in the TSD
(EPA, 1991). The following equation from Chapter 5 of the TSD is
used to calculate the LTA concentrations (alternately, Table 5-1 of
the TSD may be used):
LTA = WLA exp[0.5«2 - z« ] (Equation 11)
where,
2 = ln(CV2 + 1) for acute aquatic life criteria
= ln(CV2/4 + 1) for chronic aquatic life criteria
CV = see Table D-7
z = 2.326 for 99th percentile occurrence probability.
D-28
-------
The LTAs for the parameters that exhibited reasonable potential
are provided in Table D-15. Because silver only has an acute
WLA, only the acute LTA was calculated for this parameter.
Table D-15: Long Term Averages (LTAs) for Outfall 001
Parameter
Ammonia
Cadmium
Copper
Cyanide (WAD)
Lead
Mercury
Selenium
Silver
Zinc
Units
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Aquatic Life
acute
low flow
13
9.3
6.8
25
56
2.7
23
0.42
48
high flow
7.5
1.0
7.6
28
63
3.0
25
0.47
58
chronic
low flow
5.0
0.87
10
12
4.4
0.027
11
89
high flow
4.3
0.86
10
12
4.4
0.027
11
91
3. Calculation of Water Quality-based Effluent Limits
a. Effluent Limits Based on Aquatic Life Criteria
Once the LTA concentration is calculated for each criterion,
the most stringent LTA concentration is then used to
develop the maximum daily (MDL) and monthly average
(AML) permit limits. The MDL is based on the effluent
variability (i.e., CV of the data) and the selected probability
distribution, while the AML is dependent upon these two
variables as well as the monitoring frequency. As
recommended in the TSD, EPA used the 95th percentile as
the selected probability distribution for the AML calculation
and the 99th percentile for the MDL calculation. The MDL
and AML are calculated using the following equation from
the TSD (alternately, Table 5-2 of the TSD may be used):
MDL or AML = LTA«exp[z« -0.5«2]
for the MDL:
(Equation 12)
D-29
-------
= ln(CV2 + 1)
= 2.326 for the 99th percentile occurrence
probability
D-30
-------
for the AML:
2
n
z
= ln(CV2/n + 1)
= number of sampling events required per
month
= 1.645 for the 95th percentile occurrence
probability.
The aquatic life effluent limits for the parameters that
exhibited reasonable potential are provided in Table D-16.
Table D-16: Aquatic Life Effluent Limitations for Outfall 001
Parameter
Ammonia
Cadmium
Copper
Cyanide (WAD)
Lead
Mercury
Selenium
Silver
Zinc
Units
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
# samples
per month
4
4
4
4
4
4
4
4
4
AML
low flow
7.8
1.4
11
19
6.9
0.043
18
0.66
75
high flow
6.6
1.3
12
18
6.8
0.042
17
0.74
87
MDL
low flow
16
2.7
21
37
14
0.086
36
1.3
151
high flow
13
2.7
24
36
14
0.084
35
1.5
168
b. Effluent Limits Based on Human Health and Agricultural
Criteria
Developing permit limits for pollutants affecting human
health agriculture is somewhat different from setting limits
for aquatic life because the exposure period is generally
longer than one month and the average exposure, rather
than the maximum exposure, is usually of concern.
Because compliance with permit limits is normally
determined on a daily or monthly basis, it is necessary to set
human health and agriculture permit limits that meet a given
WLA for every month.
If the procedures described previously for aquatic life
protection were used for developing permit limits for human
D-31
-------
health and agriculture, both MDLs and AMLs would exceed
the WLA necessary to meet criteria concentrations in the
receiving water. Thus, even if a facility was discharging in
compliance with permit limits calculated using these
procedures, it would be possible to constantly exceed the
WLA. In addition, the statistical derivation procedure is not
applicable to exposure periods more than 30 days.
Therefore, the recommended statistical approach for setting
water quality-based limits for human health and agriculture
protection is to set the AML equal to the WLA, and then
calculate the MDL based on effluent variability and the
number of samples per month using the multipliers provided
in Table 5-3 of the TSD. These multipliers are the ratio of
the MDL to the AML as calculated by the following
relationship:
MDL = exp[zm« -0.5«21 (Equation 1 3)
AML exp[za- n - 0.5- n2]
where,
2 2
n =ln(CV2/n
2 2
=ln(CV2
CV = see Table D-7
n = number of samples per month
zm = 2.326 for the 99th percentile exceedance
probability of the MDL
za = 1 .645 for the 95th percentile exceedance
probability of the AML.
As stated above, EPA used the 95th percentile as the
selected probability distribution for the AML and the 99th
percentile for the MDL in this calculation.
The human health and agriculture effluent limits for the
parameters that exhibited reasonable potential are provided
in Table D-17 and D-18, respectively.
D-32
-------
Table D-17: Human Health Effluent Limitations for Outfall 001
Parameter
Ammonia
Arsenic
Cadmium
Copper
Cyanide (WAD)
Lead
Mercury
Selenium
Silver
Zinc
Units
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
# samples
per month
4
4
4
4
4
4
4
4
4
4
AML
low flow
high flow
MDL
low flow
high flow
D-33
-------
Table D-18: Agriculture Effluent Limitations for Outfall 001
Parameter
Ammonia
Cadmium
Copper
Cyanide (WAD)
Lead
Mercury
Selenium
Silver
Zinc
Units
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
# samples
per month
4
4
4
4
4
4
4
4
4
Livestock
AML
low flow
830
high flow
2,100
MDL
low flow
1,700
high flow
4,300
Irrigation
AML
low flow
330
high flow
860
MDL
low flow
660
high flow
1,700
D-34
-------
IV. Whole Effluent Toxicity (WET) Evaluation
Whole effluent toxicity (WET) is defined as the aggregate toxic effect of an
effluent measured directly by an aquatic toxicity test. WET tests are
standardized laboratory tests that measure the total toxic effect of an effluent by
exposing organisms to the effluent and noting the effects. There are two
different durations of toxicity tests: acute and chronic. Acute toxicity tests
measure the test organisms survival over a 96-hour test exposure period.
Chronic toxicity tests measure reductions in survival, growth, and reproduction
over a 7-day exposure.
MBC has conducted limited WET testing on their effluents. The current permit
required MBC to perform chronic toxicity tests on effluent collected from outfall
001. In May 1996, chronic WET tests were performed on effluent from outfall
001. Results of these tests indicated no chronic toxicity at the critical effluent
level of 3.3% based on 30 to 1 dilution. Chronic toxicity was indicated for the
outfall 001 wastewater at 33% effluent, however, this was above the critical
effluent level. In May and October of 1998 and June and October of 1999, MBC
conducted WET tests on outfall 001 and the receiving water upstream and
downstream of the outfall. Chronic toxicity was indicated at 33% effluent for one
species tested on Outfall 001 in October 1999.
Federal regulations at 40 CFR 122.44(d)(1) require that permits contain limits on
WET when a discharge has reasonable potential to cause or contribute to an
exceedence of a water quality standard. In Idaho, the relevant water quality
standard states that surface waters of the State shall be free from toxic
substances in concentrations that impair designated beneficial uses. In the
absence of state numeric criteria for WET, EPA uses 1.0 TUc and 0.3 TUa as
the chronic and acute criteria, respectively.
Since there was not an adequate amount of WET data to determine the need for
effluent limits in the draft permit, the draft permit includes WET monitoring and
establishes trigger levels for each outfall, that, if exceeded would trigger
additional WET testing and, potentially, investigations to reduce toxicity. The
trigger levels were calculated based on the WET criteria, receiving water flow,
effluent flow, and available dilution. The trigger levels were calculated using the
following mass-balance equation (this is basically the same as Equation 7):
WET toxicity trigger = [criterion (CL + (Q., MZ)1 - [C., (Q., MZ)1 (Equation
14)
Qe
where,
criterion = 1 TUcfor compliance with the chronic criterion
Qe = effluent flow
D-35
-------
Qu = upstream flow
Cu = upstream concentration = 0 for WET (assuming no
upstream toxicity)
MZ = 1, for compliance with chronic criteria (chronic WET
testing and triggers are based on 25% dilutions)
Solving equation 13 resulted in the chronic toxicity trigger value of 1.6 TUc
during low flow and 2.5 TUc during high flow in the draft permit.
V. Summary of Draft Permit Effluent Limitations
The following summarizes the proposed effluent limits developed for outfall 001.
A. Metals
The technology-based effluent limits applicable to MBC's discharges were
presented in Table D-1. The water-quality based effluent limits for metals
applicable to the discharge are shown in Tables D-16 through D-18. The
water quality-based effluent limits based on protection of aquatic life were
the most stringent limits, therefore, these effluent limits were included in
the draft permit.
B. TSS
The State does not have a water quality standard for TSS. Therefore, the
TSS limits included in the draft permit are the technology-based limits
shown in Table D-1.
C. pH
The State water quality standard for pH is 6.5 - 9.5 standard units for the
protection of aquatic life (see Table D-2). The technology-based effluent
limits specify a pH of 6.0 - 9.0 (see Table D-1). The draft permit
incorporates the more stringent water quality-based minimum of 6.5 and
the technology-based maximum of 9.0 standard units.
D. Mass-based Limits
The effluent limitations thus far have been expressed in terms of
concentration. However, with a few exceptions, the NPDES regulations
(40 CFR 122.45(f)) require that effluent limits also be expressed in terms
of mass. The following equation is used to convert the concentration-
based limits in ug/L into mass-based limits of Ib/day:
mass limit = concentration limit »Qe conversion factor (Equation 12)
D-36
-------
where,
Conversion factor = 0.008346 (units conversion from ug«mgal/L«day to Ib/day)
Qe = effluent flow rate in mgd.
The above equation was used to calculate mass-based limits for
outfall 001, where the maximum effluent flow was used to calculate
the effluent limits (per the TSD, the flows used to calculate mass-
based limits should be consistent with those used to develop the
WLAs).
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Table D-19: Summary of Proposed Effluent Limitations for Outfall 001
Parameter
Ammonia
Cadmium
Copper
Cyanide (WAD)
Lead
Mercury
PH
Selenium
Silver
TSS
Zinc
Units
mg/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
su
ug/L
Ib/day
ug/L
Ib/day
mg/L
Ib/day
ug/L
Ib/day
AML
low flow
7.8
20
1.4
0.0035
11
0.028
19
0.048
6.9
0.017
0.043
0.00011
high flow
6.6
58
1.3
0.011
12
0.11
18
0.16
6.8
0.060
0.042
0.00037
MDL
low flow
16
40
2.7
0.0068
21
0.053
37
0.093
14
0.035
0.086
0.00022
high flow
13
110
2.7
0.024
24
0.35
36
0.32
14
0.12
0.084
0.00074
within the range of 6.5 - 9.0
18
0.045
0.66
0.0017
20
50
75
0.19
17
0.15
0.74
0.0065
20
180
87
0.76
36
0.090
1.3
0.0033
30
75
150
0.38
35
0.31
1.5
0.013
30
260
170
1.5
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APPENDIX E - ENDANGERED SPECIES ACT
As discussed in Section VIII.A. of this fact sheet, Section 7 of the Endangered Species
Act requires federal agencies to consult with the National Marine Fisheries Service
(NMFS) and the U.S. Fish and Wildlife Service (USFWS) regarding potential affects a
federal action may have on threatened and endangered species.
I. Threatened and Endangered Species
According to the USFWS species list 1-4-02-SP-178, the following federally-
listed species are in the vicinity of the discharge. The species denoted by a *
are under the jurisdiction of NMFS:
Endangered Species:
Gray Wolf (Canislupus) -experimental
Sockeye salmon (Oncorhynchus nerka) *
Threatened Species:
Bald Eagle (Haliaeetus leucocephalus)
Spring/summer and fall Chinook salmon (Oncorhynchus tshawytscha) *
Steelhead trout (Oncorhynchus mykiss) *
Bull Trout (Salvelinus confluentus)
Ute' ladies-tresses (Spiranthes diluvialis)
Proposed Threatened Species:
Lynx (Lynx canadensis)
In addition to these species, the USFWS has listed two species of concern:
wolverine (Gulo gulo luscus) and white sturgeon (Accipensergentilis).
II. Consultation History
On May 22, 1992, the National Marine Fisheries Service (NMFS) listed Snake
River spring/summer Chinook salmon (Oncorhynchus tshawytscha) as a
"threatened" species under the Endangered Species Act. As a result, the USFS
engaged in consultation with NMFS under section 7 of the Endangered Species
Act. This consultation was conducted by the USFS as "lead agency" on behalf
of both EPA and the Corps. As a result of this consultation, NMFS issued a
biological opinion (BO) on March 31, 1994, finding that the Mine's operations
were not likely to jeopardize the continued existence of salmon. Thus, the
existing NPDES permit was not modified.
Subsequently, the 1994 BO was challenged in court by the Idaho Rivers United,
the Golden Eagle Audubon society, the Boulder-White Clouds Council, and the
Sierra Club, collectively. The applicable legal standard for the challenge was
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the arbitrary, capricious, or contrary to law standard of the Administrative
Procedures Act. Additionally, NMFS reclassified the spring/summer Chinook as
endangered in 1994, but that reclassification expired in April 1995 so the Snake
River Chinook are again classified as threatened. Since federal agencies are
required to consult on threatened or endangered species, these changes in the
classification of the Chinook did not affect the need to consult with NMFS.
On November 9, 1995, the U.S. District Court for the Western District of Seattle
ruled that the USFS and EPA must reinitiate consultation with regard to the
impacts of the Beartrack Mine regarding two species of the Snake River Chinook
salmon which are classified as "threatened" under the Endangered Species Act.
The court found that the BO issued by NMFS, after consultation with the USFS
as the lead agency, inadequately considered the impacts of the mining operation
on the salmon. Based on its finding that the biological opinion was arbitrary and
capricious, the court ordered the agencies to reinitiate consultation with NMFS.
The new consultation was required to address deficiencies noted by the court
and to take into consideration any other relevant factors, including additional
information available about other projects in the Panther Creek watershed.
However, the plaintiffs did not request and the court did not order the Mine's
permit to be revoked, therefore, the permit remained in effect.
When NMFS began to reinitiate consultation, they conducted several site
studies in the Spring of 1996 to determine whether upstream passage of adult
chinook salmon was possible through Napias Falls. NMFS determined that the
upper reaches of Napias Creek may have been accessible historically, and thus
should be considered as constituting critical habitat. On January 6, 1997, the
Secretary of Commerce received a petition from MBC to revise the critical
habitat for the Snake River spring/summer chinook salmon in Napias Creek.
However, NMFS moved forward on the preparation of the BO and issued a
jeopardy decision on March 12, 1999, which identified Reasonable and Prudent
Alternatives (RPAs) that would allow the continuation of the activity. The RPAs
were directed at several federal agencies, including the EPA for the issuance of
the NPDES permit.
Then on October 25, 1999, NMFS published a rule in the federal register
revising critical habitat for Snake River spring/summer chinook salmon excluding
the areas above Napias Creek Falls from designated critical habitat for this
species. However, the RPAs listed in the 1999 BO were not revised and are still
in effect. These RPAs under EPA responsibility that apply to the reissuance of
this permit are as follows:
RPA #3 NPDES permit levels need to be re-evaluated with special
consideration to the mixing zone, upstream metal concentrations,
low hardness of the receiving water, and actual discharge flow
rates. NMFS concern is that the effluent mixing zone could be a
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chemical barrier to salmon and steelhead migration. The EPA
shall consult with NMFS regarding recalculation of the NPDES
permit limits, including development of wasteload allocations and
the uncertainty of low hardness in the receiving water.
RPA #5 The EPA shall address the issue of ambient water quality criteria
(AWQC) standards, detection limits, and hardness. Detection
limits should be at a level that would allow the collection of
meaningful water quality information, whether using Idaho water
quality criteria or site-specific criteria. Consequently, the Quality
Assurance Plan (QAP) requirements must be updated to include
the appropriate sample collection, shipping and testing procedures.
Additionally, EPA shall implement a metals monitoring strategy to
more accurately determine ambient water quality using appropriate
detection limits. If the metals are found to exceed AWQC, then an
appropriate action plan must be develop that reduces the
concentrations to levels that will not adversely affect threatened
and endangered species. The evaluation and proposed solutions
are to be reviewed and approved by NMFS and incorporated into
MBC's Plan of Operations (POO) and NPDES permit. The NPDES
permit and standards shall receive NMFS review and concurrence
before adoption.
NMFS RPAs from 1999 BO Addressed in Proposed NPDES Permit
RPA #3 The wasteload allocations in the current permit were based on
estimates of receiving water flow, effluent flow, and the upstream
concentrations were assumed to be zero. The wasteload
allocations for the draft permit were developed based on measured
upstream metal concentrations, and actual receiving water and
discharge flow rates. The draft permit also considered the dilution
from the mixing zones authorized by the state of Idaho and the low
hardness of the receiving water. The following generally discusses
the different variables used in development of the effluent
limitations proposed in the draft permit. Refer to Section III.D.1 of
Appedix D in this fact sheet for more detailed discussion of the
development of the wasteload allocation.
Critical Flows
The critical flows used to develop effluent limits in the draft permit
are based on measured flows from the USGS gaging station
whereas the effluent limits in the current permit were based on a
dilution ratio of 30:1 (receiving water to effluent). To obtain the
dilution ration, both the receiving water and effluent flow rates were
E-3
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estimated by a contractor for MBC from four months of data from
the Napias Creek gage (June through September 1989), basin
yields of gaged receiving waters in the region, and average annual
precipitation measured at locations within the same region. This
analysis only estimated the 1Q10 flow, which would not have
adequately protected the duration period for the chronic toxic
effects. Additionally, the data shows that between 1996 and 1999
there were 517 days that the actual flow ratio was less than 30:1.
This means that the effluent limits in the current permit may not be
protective of water quality standards about one third of the time.
EPA recommends the use of the 1Q10 flow and the 7Q10 flow for
protection of aquatic life. These hydrologically based flows are
similar to a biologically based 1B3 and 4B3 for most streams,
which accounts for specific toxicological effects of a pollutant and
biological recovery times from localized stresses. The critical flows
used for the draft permit were derived from data collected from
United States Geological Survey (USGS) station on Napias Creek
and corrected to provide the upstream flow by subtracting out the
effluent flow rate.
Additionally, the wasteload allocations and effluent limitations were
developed for both the high and low flow conditions. The
application of tiered effluent limits are more protective of the
aquatic environment during the low flow periods because the
average flows during this period do not account for the peak flows
in May and June. If effluent limits were developed based on the
annual averages that included the peak flows, then the resulting
effluent limits would have been greater than the proposed limits for
the low flow period and would have a higher potential to cause
toxic effects during low flow conditions.
Mixing Zones
MBC has recently installed a new diffuser that will decrease the
physical boundary of the mixing zone by promoting more rapid
mixing in the receiving water than their previous diffuser. The
IDEQ will model the mixing zones for the draft permit based on
actual receiving water flow, effluent flow data and the new diffuser
design to ensure that the chemical mixing zones would not cause a
fish migration barrier. IDEQ will provide the results of the model,
including mixing zone boundary dimensions, with their certification
of this permit under Section 401 of the Clean Water Act. Since
outfall 001 is above Napias Falls and Napias Falls has been
determined a fish passage barrier and the mixing zones do not
E-4
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extend to Napias Falls, EPA concludes that the mixing zones
proposed in this draft permit would not cause a chemical fish
migration barrier to salmonids. However, there are bull trout, which
is a threatened species under the USFWS, located above Napias
Falls that need to be considered in the mixing zone assessment.
The physical boundaries and dimensions of the mixing zone(s) will
be discussed in the Biological Evaluation submitted to NMFS and
USFWS subsequent to EPA receiving a final 401 certification from
IDEQ.
The effluent limits in the draft permit are based on actual critical
flows in the receiving water and lower dilution volumes (25 percent
critical flow volume in the draft permit versus 100 percent critical
flow volume in current permit) for protection of aquatic life.
Upstream Concentration
The wasteload allocations used to develop effluent limitations in
the current permit assumed upstream concentrations were zero.
Since the beginning of mine operations in 1989, MBC has been
monitoring the receiving waters monthly at several points in Napias
Creek upstream and downstream of Outfall 001. EPA used the
receiving water data collected by MBC at Station WQ-22, which is
located above Outfall 001 and the confluence of Arnett Creek (see
Figure A-3 for monitoring station location), from 1997 through 2000
to calculate upstream concentrations Therefore, any additional
concentration loadings from Arnett Creek are not included in the
analysis of the wasteload allocation because there was no data
available.
Two difficulties were encountered in evaluating the receiving water
data from WQ-22. First, much of the data was reported as
non-detect and in some cases the detection limits exceeded the
water quality criteria. Second, much of the non-detect data had
more than one detection level. Therefore, EPA made the following
assumptions for the upstream concentrations in developing the
wasteload allocations for the discharge from Outfall 001:
where all or most of the data were non-detect (<10 detected
values), zero was assumed; and
where all or most of the data were detected (>10 detected
values), the 95th percentile of the detected values was
assumed.
E-5
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As a result of these assumptions, the upstream concentration for
most parameters were zero, except for ammonia, iron, manganese,
nickel, pH, total dissolved solids, total suspended solids, sulfate
and turbidity. Therefore, assuming an upstream concentration of
zero when most of the data was non-detect at detect levels less
than the criteria may allow a larger wasteload allocation than
should be allowed and may result in a mixing zone that is larger
than what was allowed by the state of Idaho. This may be the case
for cyanide, selenium and zinc. Additionally, assuming an
upstream concentration of zero when most of the data was non-
detect at detect levels greater than the criteria may allow a larger
wasteload allocation than should be allowed and may result in the
state of Idaho authorizing a mixing zone when the stream is
already at or above its capacity for additional loading. This may be
the case for cadmium, copper, lead, mercury and silver.
In order to conduct a more accurate assessment in the future, the
draft permit has proposed receiving water monitoring using
methods that can detect at or below the criteria for Napias Creek.
Effluent Flow
As previously addressed in the critical flow discussion, the
wasteload allocations for the current permit were based on an
estimated dilution ratio of 30:1. However, this dilution ratio was
never enforced through the permit and the data shows that this
dilution ratio was not met at least one third of the time.
Additionally, the mass loadings in the current permit were based on
the estimated effluent low flow of 1.09 mgd that corresponded to
the period (May) when dilution ratio was estimated to be 30:1.
For the draft permit, the effluent flows used to calculate the
wasteload allocations and effluent loading limits were the maximum
flows that the company will discharge for each flow season. The
use of the maximum flow allowed the development of effluent limits
that are highly probable to be protective of water quality standards.
Hardness
Pollutants with water quality criteria that are affected by hardness
that are of concern for this discharge include cadmium, chromium,
copper, lead, nickel, silver and zinc. In developing wasteload
allocations for the current permit, a receiving water hardness of 10
mg/L as calcium carbonate was assumed. The fifth percentile of
measurements downstream of Outfall 001 is 6 mg/L hardness as
E-6
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calcium carbonate during the low flow period and 3.7 mg/L
hardness as calcium carbonate.
The water quality standards for the state of Idaho incorporates the
toxic criteria set forth in 40 CFR 131.36(b)(1) (i.e., the National
Toxics Rule), as of July 1, 1993, which specifies a hardness range
of 25 to 400 mg/L as calcium carbonate. When the measured
hardness falls below the low end cap for the criteria, the regulation
(40 CFR 131.36(c)(4)) states that the minimum hardness allowed
for use in the hardness-based equations for the criteria is 25 mg/L
as calcium carbonate. Therefore, the hardness used to develop
the wasteload allocation for the draft permit was 25 mg/L as
calcium carbonate.
As a comparative analysis, the differences in using a hardness of
25 mg/L as calcium carbonate versus the actual hardness are
provided in the following tables. Table E-1 provides a comparison
of the criteria, Table E-2 compares the differences in the mixing
zones, Table E-3 shows the differences in the reasonable potential
determination, Table E-4 indicates the differences in the effluent
limitations, and Table E-5 contains the comparison of the actual
compliance evaluation levels.
The main difference between using the actual hardness and a
hardness of 25 mg/L as calcium carbonate is that an effluent
limitation for nickel would be required using actual hardness. For
this reason, the draft permit proposes monitoring of the effluent
and receiving water for nickel. Additionally, most of these
pollutants are at or below the capability of current analytical
technology approved by EPA in 40 CFR 136. Therefore, the
minimum level (or quantification level) for the best available
analytical technology becomes the compliance evaluation level.
This resulted in compliance evaluation levels that are essentially
the same, with the exception of zinc, even though the effluent limits
for the actual hardness may be lower than effluent limits based on
a hardness of 25 mg/L.
E-7
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Table E-1 : Comparison of Hardness-Based Aquatic Life Criteria
Parameter
Cadmium
Chromium
Copper
Lead
Nickel
Silver
Zinc
Units
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Actual Hardness
Acute Criteria
low flow
(h=6.0 mg/L)
0.16
71
1.2
2.7
131
0.03
11
high flow
(h=3.7 mg/L)
0.09
52
0.8
1.5
86
0.01
6.9
Chronic Criteria
low flow
(h=6.0 mg/L)
0.13
28
1.0
0.11
15
9.6
high flow
(h=3.7 mg/L)
0.13
28
1.0
0.11
15
9.6
25 mg/L Hardness
Acute Criteria
low flow
0.82
192
4.6
14
438
0.32
35
high flow
0.82
192
4.6
14
438
0.32
35
Chronic Criteria
low flow
0.37
68
3.5
0.54
49
32
high flow
0.37
68
3.5
0.54
49
32
E-8
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Table E-2: Comparison of Mixing Zone Dilutions
for Hardness-Based Aquatic Life Criteria
(expressed as percent of receiving water flow)
Parameter
Cadmium
Chromium
Copper
Lead
Nickel
Silver
Zinc
Footnote:
Actual Hardness
low flow
(h=6.0 mg/L)
25
O1
25
25
25
25
25
high flow
(h=3.7 mg/L)
25
25
25
25
25
25
25 mg/L Hardness
low flow
25
O1
25
25
25
25
25
high flow
25
O1
25
25
25
25
1 . A mixing zone was not necessary for this parameter because reasonable potential was
not determined when no dilution was used in the calculations.
Table E-3: Comparison of Reasonable Potential Analysis
for Hardness-Based Aquatic Life Criteria
Parameter
Cadmium
Chromium
Copper
Lead
Nickel
Silver
Zinc
Actual Hardness
low flow
y
n
y
y
n
y
y
high flow
y
n
y
y
y
y
y
25 mg/L Hardness
low flow
y
n
y
y
n
y
y
high flow
y
n
y
y
n
y
y
E-9
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Table E-4: Comparison of Hardness-Based Effluent Limitations
Parameter
Cadmium
Copper
Lead
Nickel
Silver
Zinc
Footnotes:
Units
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
Actual Hardness
AML
low flow
0.271
0.00068
2.82
0.0070
1.43
0.0035
0.0574
0.00014
22
0.055
high flow
0.171
0.0015
1.92
0.017
1.33
0.011
66
0.58
0.0274
0.00024
17
0.15
MDL
low flow
0.55
0.0014
5.5
0.014
2.73
0.0068
0.114
0.00028
45
0.11
high flow
0.301
0.0026
3.92
0.034
2.73
0.024
130
1.1
0.0544
0.00047
33
0.29
25 mg/L Hardness
AML
low flow
1.4
0.0035
11
0.028
6.9
0.017
0.664
0.0017
75
0.19
high flow
1.3
0.011
12
0.11
6.8
0.042
0.744
0.0065
87
0.76
MDL
low flow
2.7
0.0068
21
0.053
14
0.035
1.3
0.0033
150
0.38
high flow
2.7
0.024
24
0.35
14
0.12
1.5
0.013
170
1.5
1 . This effluent limit is not quantifiable using EPA approved analytical methods. The permittee will be in compliance with the effluent limit
provided the measured concentration is at or below the compliance evaluation level of 0.5 u/L using EPA Method 21 3.2.
2. This effluent limit is not quantifiable using EPA approved analytical methods. The permittee will be in compliance with the effluent limit
provided the measured concentration is at or below the compliance evaluation level of 5 u/L using EPA Method 220.2.
3. This effluent limit is not quantifiable using EPA approved analytical methods. The permittee will be in compliance with the effluent limit
provided the measured concentration is at or below the compliance evaluation level of 5 u/L using EPA Method 239.2.
4. This effluent limit is not quantifiable using EPA approved analytical methods. The permittee will be in compliance with the effluent limit
provided the measured concentration is at or below the compliance evaluation level of 1 .0 u/L using EPA Method 272.2.
E-10
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Table E-5: Comparison of Compliance Evaluation Levels
Parameter
Cadmium
Copper
Lead
Nickel
Silver
Zinc
Units
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
ug/L
Ib/day
Actual Hardness
AML
low flow
0.5
0.0013
5.0
0.013
5.0
0.013
1.0
0.0025
22
0.055
high flow
0.5
0.0044
5.0
0.044
5.0
0.044
66
0.58
1.0
0.0088
17
0.15
MDL
low flow
0.55
0.0014
5.5
0.014
5.0
0.014
1.0
0.0025
45
0.11
high flow
0.5
0.0044
5.0
0.044
5.0
0.044
130
1.1
1.0
0.0088
33
0.29
25 mg/L Hardness
AML
low flow
1.4
0.0035
11
0.028
6.9
0.017
1.0
0.0025
75
0.19
high flow
1.3
0.011
12
0.11
6.8
0.060
1.0
0.0088
87
0.76
MDL
low flow
2.7
0.0068
21
0.053
14
0.035
1.3
0.0033
150
0.38
high flow
2.7
0.024
24
0.35
14
0.12
1.5
0.013
170
1.5
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RPA #5 The method detection levels for the analytical testing required in
the draft permit, for both effluent and receiving water monitoring,
are at a level that would provide useful environmental information
(i.e., less than the AWQC for receiving water monitoring) and
determine compliance with the permit (i.e., less than the effluent
limitation). EPA has also required the applicant to update their
Quality Assurance Plan (QAP) and has included some specific
requirements to ensure a satisfactory QAP.
The effluent limits in the draft permit are based upon the applicable
Idaho water quality criteria for Napias Creek. The proposed permit
requires MBC to report any exceedances of the effluent limits or
any noncompliance that may endanger the environment within 24
hours. MBC must also report on the steps taken to reduce,
eliminate, and prevent recurrence of the noncompliance.
Depending upon the nature and extent of the violations, EPA will
determine what further action(s) are necessary, which may include
the investigations described in this RPA item. In addition, the draft
permit requires downstream monitoring to determine the
effectiveness of the proposed effluent limits. Should this
monitoring indicate that the effluent limits are not effective in
protecting Idaho water quality standards, then the permit may be
modified to adjust the effluent limits.
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APPENDIX F - ESSENTIAL FISH HABITAT
As discussed in Section VIII.B. of this fact sheet, the Magnuson-Stevens Fishery
Conservation and Management Act requires federal agencies to consult with the
National Marine Fisheries Service (NMFS) regarding potential affects a federal action
may have on essential fish habitat (EFH). The NMFS has requested that EFH
assessments contain the following requirements:
Action Agency
US Environmental Protection Agency, Region 10
Project Name
Reissuance of the National Pollutant Discharge Elimination System (NPDES) permit to
Meridian Beartrack Company (MBC) for the Beartrack Mine.
Species in the Vicinity of the Project
The Salmon-Panther Subbasin, HUC 17060203, has been designated to support
chinook salmon (Oncorhynchus tshawytscha) for EFH, according to NMFS website at:
http://www.nmfs.noaa.gov/habitat/habitatprotection/efh designations.htm
Description of the Project/Proposed Activity
The facility activities are described in Part II of this fact sheet, wastewater sources are
described in Appendix C, and the discharge location is described in Part IV.A.
Evaluate Potential Effects to EFH
The EPA has tentatively determined that the issuance of this permit will not affect any
EFH species in the vicinity of the discharge for the following reasons:
1. The proposed permit has been developed in accordance with the Idaho water
quality standards to protect aquatic life species in Napias Creek. NPDES
permits are established to protect water quality in accordance with State water
quality standards. The standards are developed to protect the designated uses
of the waterbody, including growth and propagation of aquatic life and wildlife.
Self-monitoring conducted by the applicant indicates that the facility will be able
to comply with all limits of the proposed permit.
2. The derivation of permit limits and monitoring requirements (refer to Section III of
this fact sheet for specifics pertaining to the proposed permit) for an NPDES
discharger are in accordance with state water quality standards using
procedures prescribed in the TSD (EPA, 1991).
3. On October 25, 1999, NMFS published a rule in the federal register revising
critical habitat for Snake River spring/summer chinook salmon excluding the
areas above Napias Creek Falls from designated critical habitat for this species.
F-1
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Therefore, it is concluded that there are no critical habitats in the vicinity of the
discharge for any species of Chinook salmon.
4. The draft permit implements/addresses the Reasonable and Prudent measures
for protection of Chinook salmon identified by NMFS in the 1999 BO.
F-2
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APPENDIX G - REFERENCES
EPA 1988. NPDES Permit No. ID0027022. Issued September 30, 1991.
EPA 1991. Technical Support Document for Water Quality-based Toxics Control.
Office of Water Enforcement and Permits, Office of Water Regulations and Standards.
Washington, D.C., March 1991. EPA/505/2-90-001.
EPA, 1996a. EPA Region 10 Guidance For WQBELs Below Analytical
Detection/Quantitation Level. NPDES Permits Unit, EPA Region 10, Seattle, WA.
March 1996.
EPA, 1996b. The Metals Translator: Guidance for Calculating a Total Recoverable
Permit Limit from a Dissolved Criterion, EPA 823-B-96-007, June 1996.
IDAPA. 1996. Idaho Administrative Procedures Act 58, Title 01, Chapter 02: Water
Quality Standards and Wastewater Treatment Requirements.
MBC, 1990. Meridian Gold Company (aka Meridian Beartrack Company) and Steffen
Robertson and Kirsten, Inc. May 1991. Reclamation Plan Permit Application Technical
Report Beartrack Gold Project - Amended.
MBC 1996. FMC Gold Company. May 1, 1996. NPDES Permit Application for Outfalls
001, 003 and 004.
MBC 2000a. Meridian Beartrack Company. May 8, 2000. NPDES Permit Renewal
Application Supplemental Information Report.
MBC 2000b. Meridian Beartrack Company. June 26, 2000. Replacement Pages for
Meridian Beartrack Company NPDES Permit Renewal Application, Supplemental
Information Report.
MBC 2000c. Meridian Beartrack Company. August 21, 2000. Mixing Zone Analysis
for Beartrack Mine, Outfall 001, Napias Creek, Lemhi County, Idaho.
NMFS 1999. Endangered Species Act Section 7 Biological Opinion on the Meridian
Gold Company Beartrack Gold Project. National Marine Fisheries Service, Northwest
Region. March 12, 1999.
USDC (Idaho) 1999. Meridian Beartrack, Co. and Meridian Gold Co. vs. NMFS et al.
US District Court for the District of Idaho. No 99-0009-E-BLW. June 22, 1999.
USDC (Seattle) 1995. Idaho Rivers United et al. vs. NMFS et al. US District Court for
the Western District of Seattle. No C94-1476R. November 9, 1995.
G-1
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USFS 1991. Beartrack Gold Project Final Environmental Impact Statement. Salmon
National Forest, Lemhi County, Idaho. US Forest Service, Intermountain Region.
June, 1991.
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