EPA 910-R-99-016
United States
Environmental Protection
Agency
Office of Water
Region 10
1200 Sixth Avenue
Seattle WA 98101
Alaska
Idaho
Oregon
Washington
November 1999
&EPA
EPA and Hard Rock Mining:
A Source Book for Industry in the
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 10
1200 Sixth Avenue
Seattle, WA 98101
Reply To
Attn Of: OW-135 November 23, 1999
To all interested parties:
The Region 10 Office of the U.S. Environmental Protection Agency (EPA) is pleased to
announce the availability of a new draft report entitled EPA and Hard Rock Mining: A Source
Book for Industry in the Northwest and Alaska. Region 10 is soliciting public comment on this
draft report, generally referred to as the Mining Source Book, until March 31,2000.
Hard rock mining plays a very important role in the U.S. economy, particularly in rural
areas. Mining projects, however, are generally very complex, often controversial, and may be
subject to permit requirements by a host of state, federal and local agencies. Consequently,
permitting of new mines can be very difficult and time consuming. The Mining Source Book has
been developed to streamline the permitting and NEPA review process by providing industry,
agencies and the public a clear explanation of the EPA's duties and authorities for the permitting
of new mines, and a summary of the typical information and analysis needed to support CWA
permitting and NEPA disclosure. This is based on our experience permitting and reviewing
proposed mining projects, as well as our experience following up on unexpected conditions that
have arisen at operating mines in the Northwest and Alaska. This draft document intends to
respond to concerns raised by the mining industry that EPA's requirements or expectations are
not well understood and are not articulated early in the permitting and NEPA process, thus
leading to increased costs and delays. Our hope is that this document will ultimately result in
more timely and better informed decisions on proposed projects.
;
The Mining Source Book's primary focus is on the Clean Water Act (CWA) permitting
processes and the associated National Environmental Policy Act (NEPA) compliance process.
The report includes a main text that explains, in plain English:
• the CWA's National Pollutant Discharge Elimination System (NPDES)wastewater
discharge permitting process;
• the CWA's Dredge and Fill permit process;
• EPA's role in associated NEPA analyses for new mining projects;
• a summary of the Endangered Species Act and Clean Air Act requirements;
• a discussion of information that Region 10 generally needs to complete the CWA
permitting and NEPA processes for new mining projects.
o
Printed on Recycled Paj
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Nine technical appendices are included that review available methods for developing this
information. It is our hope that by clearly articulating what information is generally needed for
CWA permitting, permit applicants will be better able,,to plan, for gathering this information early
in the mine exploration and pre-developrnent stages. We also believe that the Mining Source
Book will help other agencies involved with permit processes for new mines, in particular land
management agencies, understand how respective jurisdictions for protecting water and other
resources may overlap and can be better coordinated. Lastly, we would hope that the general
public and all stakeholders in new mine development would find the draft Mining Source Book
of interest and of help in evaluating and minimizing the environmental impacts of new mining
projects.
The draft report EPA and Hard Rock Mining: A Source Book for Industry in the
Northwest and Alaska can be found at the EPA Region 10 web site at
www.epa.gov/rlOearth/water.htm. Hard copies may be requested by calling Bill Riley, Office of
Water Mining Coordinator at (206) 553-1412 or toll free at 1-800-424-4EPA. Copies may also
be requested via e-mail at riley. william@ epa. gov or in writing:
Bill Riley, Mining Coordinator
Region 10 EPA Office of Water, m/s OW-135
1200 Sixth Ave.,
Seattle, Washington 98101
Comments should be mailed not later than March 31,2000 to Mr. Riley at the address
above (or via e-mail). Following receipt of comments, Region 10 intends to finalize the
document by the fall of 2000. If considerable interest is expressed in specific topics, the Region
will consider holding workshops with interested parties during the spring and/or summer of
2000. Thank you for your interest in environmentally sound mining.
Sincerely,
Randy SmitrnDirector
Office of Wafer
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TABLE OF CONTENTS is £PA i
Section
i.o
2.0
3.0
4.0
5.0
6.0
INTRODUCTION 1
1.1 Purpose of this Document 1
1.2 Problem Statement *. ' 2
1.3 General Suggestions for Completing the Permitting Process ' :? 2
1.4 Organization of this Source Book : 1 4
/A v
f/ - '
INTRODUCTION TO NPDES PERMITTING (CWA SECTION 402)" V* -.-. r... 5
2.1 When is an NPDES Permit Needed? Y 8
2.2 Technology-based National Effluent Limitation Guidelines 10
2.3 Water Quality Standards and Water Quality-Based^ermitting 13
2.4 Storm Water "T...-. 17
2.5 Information Needs for NPDES Permitting ; 19
DISCHARGE OF DREDGED
OF THE U.S. (SECTION 404) ... 22
THE NATIONAL ENVIRONMENTAL PDLICY ACT ...... $.+ J* ..................... 23
4.1 EPA's NEPA Role ....... ?.\ ....... '! ....... : . !" ........................ 24
4.2 EPA Requirements for EBvironmental Review Under NEPA and the CWA ...... 25
4.3 When is an EIS Requi??. '.....: ....... :- .............................. 28
•..' ................................ 29
29
.ce Standards ............................... 31
31
33
Impacts
6.1.1
6.1.2
2 Impacts
6.2.1
6.2.4
6.2.5
6.2.6
6.2.7
IMPACT ASSESSMENT .......................... 37
to Water. Hydrology ........................... 37
Surfajflfler Hydrology ........................................ 38
Grou Water Hydrogeology ..................................... 42
Quality ............................................... 44
kground and Existing Water Quality ............................ 45
egional Hydrology and Hydrogeology ............................. 46
Hydrology of Mines and Waste Facilities ........................... 46
Solid Waste and Materials Characterization and Management ........... 47
Wastewater Quality and Management .............................. 48
Post-Closure Mine and Waste Facility Water Quality .................. 49
Closure and Reclamation Effects .................................. 50
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6.3 Impacts to Aquatic Resources 50
6.4 Impacts to Wetlands 52
7.0 REFERENCES 54
Appendix A: Hydrology ;fitti
Appendix B: Receiving Waters
Appendix C: Characterization of Ore, Waste Rock and Tailings '?
Appendix D: Effluent Quality
Appendix E: Wastewater Management , ' • ~ J?
Appendix F: Solid Waste Management ;%!?"
Appendix G: Aquatic Resources ' *. '
Appendix H: Erosion and Sedimentation **'>>.
Appendix I: Wetlands
LIST OF TABLES U
' ^ ff-
Table 1. Categories of Discharges from Mines .>l/^\.\', \. ;/t 9
Table 2. Industry Sectors and Types of Applicable Laraiti40 GfR.Part 440 12
Table 3. Selected Definitions and Provisions in 40OFR Part 44PT* 12
Table 4. EPA Forms Required for NPDES Application ../.'../ 20
Table 5. Overview of Information Needs for NPDES Permitting 21
Table 6. Potential Emission Sources^ Mine Sites ... ^// 31
Table 7. Data Needs for NEPA Review and CWA Permits 39
Table 8. Testing Needs for NEPA Review and CW&Termits 40
Table 9. Preliminary Design Needs for NEPA Review and CWA Permits 41
Table 10. Data Analysis Needs for NEPA Review and CWA Permits 42
^ , '/,
, f t,
* v --°
-.""-' \* ~ l /:LIST OF FIGURES
' if1-
% & ^ I:
Figure 1.' NPDES Permitting Process 7
Figure 2. Example of Discharge Classification Depending on Wastewater
a * Source and Management ; 14
Figure 3 A. Informal Consultation Under the Endangered Species Act 35
Figure 3B. Formal Consultation Under the Endangered Species Act 36
ii November 1999
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1.0 INTRODUCTION
1.1 Purpose of this Document
This 'Source Book' was prepared by the Environmental Protection Agency (EPA) Region
10 Office to provide guidance on the Clean Water Act (CWA) permitting processes*and
associated National Environmental Policy Act (NEPA) environmental review requirements for
new metal mining operations.1 This guidance has three specific purposes. First, it is intended to
explain the specific requirements of the CWA as they may pertain to new mines. It is hoped that
a better understanding of EPA's mandates and authorities will provider basis for understanding
why certain information is often requested as part of the CWA permitting processes: Second,
this document describes the types of information that EPA Region 10 generally needs to process
permit applications and perform environmental reviews in an efficient and timely mariner. By
articulating these information needs, the Region hopes that the mining industry will realize time
and cost savings during the permitting process by avoiding surprises, false starts, and the need for
additional gathering and/or analysis of technical data. Finally, the guidance is intended to
promote predictability and consistency within Rejpl^iOJo ensure mine development, operation,
11 • • . 11 „ ' fcSilfil, -<« •>/!&., „„?..«
and closure occur in an environmentally sour
Given the unique character of each mining
in which they may operate, it is impracjipal for
would apply to all sites. Consequejiljyjthis d
not view anything in this guidan
follow naturally from the discu
Among th
closure?:
andgro
ecosystems
mitigated?
;t impo:
disch
tamut
Jhe pro
variety of environments
egion Iplevelop specific guidance that
ient is gelieral in nature and applicants should
mandatory'. However, there are several questions that
s contained hereipMid that will be asked of most applicants.
ill there bea'disebarge of wastewater during operations and/or
ater quality standards? What is the long-term risk of surface
SJ1 reclamation restore the integrity of aquatic and terrestrial
can unacceptable environmental impacts be avoided or
'This Source
ttional Corpo
was completed with the assistance of Science Applications
n under EPA contract 68-C4-0034. Jack Mozingo and Ron Rimelman were the
The project was managed by Jennifer Sachar in EPA's Office of Wastewater
Riley, the Mining Coordinator of EPA Region 10's Office of Water.
lis document is not intended, nor can it be relied on, to create any rights enforceable by any
party in litigation with the United States. This document does not constitute a legal opinion, nor does it
represent Agency policy or guidance for meeting any regulatory requirement. Any mention of company
or product name is not to be considered an endorsement by the U.S. Government or by the Environmental
Protection Agency.
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1.2 Problem Statement
There is general agreement among interested parties that it is becoming increasingly
difficult to permit new mines. Mining operations typically are complex undertakings that may be
situated in or near complex and sensitive environments. Predicting how a particulaijnine may
^"^ ^S^is^''
affect the environment during its active life and following closure is no simple tasf i In EPA
Region 10, new mines present a significant challenge for those who develop CWA Section 402
National Pollutant Discharge Elimination System (NPDES) permits,
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be more "environmentally friendly." A common problem is that applicants do not collect data
that satisfy the environmental permitting process. For example, metal constituents in surface
water samples may be measured using methods with detection limits that are higher than water
quality standard values. Other examples would be when geochemical or hydrological and
hydrogeological studies are conducted only to satisfy objectives associated with mine
development and not to help evaluate potential environmental impacts as well.
Applicants can help to minimize delays during NEPA and CWA permit application
processes by considering the following general suggestions: "
{ *" «*!
• Evaluate possible environmental data requirements and initiate environmental
planning on the front end. ' - - '< ' , ,L * . '
_ fl $ t v^lF "? * y
• Collect data to meet specific environmental objectives'or requirements, and collect
them at the required levels of detail and precision ',-/
• Provide adequate data and analyses for all proposed-atematives.
• Be flexible when choosing facility designs, locations,«and technologies.
• Propose use of treatment, disposal, and reclamation teehaologies with demonstrated
records of success.
• Use appropriately conservative
• Be pro-active in resolving po
• Establish open lines of commumbation ||ph state regulatory and land
management agencies that^ffl' overseeihe procejl»g of the permit application(s) very
early in the process, not jiier idata aretcollected md planning is near completion.
JSpS""' * •'"
Maintain these lines offfprmiumcMion throughout the review and permitting process,
and then throughout t||pife of the;mine aadfafterward.
slans and data||ia!ity objectives with the appropriate
|p gathering^ me data.
and interpretations.
Rfetiew data co.
Becau&
provide a variet
cost saving
will enabjpli complei
levelj||f|f precision
potgjiial impacts to s
than that requi
A review processes typically require an applicant to
of detail and precision, applicants are likely to realize
potellial data needs from the outset of a proposed project. This
set of data to be collected efficiently and at the required
y% data gaps or overlap. In order to specifically evaluate
ground water resources, applicants may need to study an area
the mining operation; a common approach is to use a watershed
encouraged to evaluate different mine layouts, facility designs, and
ran effort to minimize the potential for environmental impact during and
folloWlSf "operation. If newly developed or unproven treatment or disposal technologies are
proposed to be used, applicants can expect to be asked to provide the results of bench- or pilot-
scale tests conducted to evaluate the effectiveness of the technology and to institute more detailed
monitoring to demonstrate their effectiveness.
November 1999
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Finally, applicants will find that impact analyses often require assumptions of future
conditions, waste behavior, and land uses. This is especially true for interpretations,
extrapolations, and modeling of geochemical test results and site hydrology evaluations (e.g.,
water balances). In all cases, applicants should aim to be conservative in their judgment of future
conditions and waste behavior and be able to justify their assumptions and interpretations. As
with data cpllection, applicants are strongly encouraged to discuss sampling and data analysis
plans, including assumptions and uncertainties, with the appropriate regulators prior to
performing the analyses. ;
f' j
1.4 Organization of this Source Book . , *
1 i '
The remainder of the main text of the source book describes, the major environmental
programs that apply to hardrock mining, and the types of information that EPA needs in order to
issue permits, conduct reviews, and otherwise fulfill its le^oWigations. Sections^O and 3.0
describe Clean Water Act programs: section 2.0 provides ato-overview of NPDES permitting,
including many of the major components of the NPDES program, and^section 3.0 describes the
§404 program, under which dredge and fill activities are permitted. •Section 4.0 covers the
National Environmental Policy Act, which requires an analysis of thfe^vkonmental impacts of
proposed Federal actions, including the issuangfiiif permits^ Section SfO covers the requirements
of the Clean Air Act and the Endangered Species Act. j^iaigj^ section 6.0 summarizes the types
of effects that mining can have, and the t$pes of anMyses^o4Jcf|aErnation that EPA expects from
project proponents in applications for permits andin docunieats-and other materials that have to
be reviewed and/or approved by EPA.
/ ' ?s
The Source Book includes nine technical appendices that describe the major issues that
must be understood and addressed in order to understand and control the impacts from mining
operations". "j||||endices include the following:
Hydrology .<-
: Receiving Waters
Apjpendix C: Characterization of Ore, Waste Rock, and Tailings
gf Appendix D: Effluent Quality
Appendix E: 'Wastewater Management
Appendix F: Solid Waste Management
Appendix G: Aquatic Resources
Appendix H: "Erosion and Sedimentation
Appendix!: Wetlands
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2.0 INTRODUCTION TO NPDES PERMITTING (CWA SECTION 402)
The objective of the Clean Water Act is to "restore and maintain the chemical, physical,
and biological integrity of the Nation's waters" (§101 (a)). This is to be accomplished through the
control of both point and nonpoint sources of pollution (§101 (a)(7)). A number of interrelated
provisions of the Act establish the structure by which the goals of the Act are to be achieved.
Within this overall structure, a variety of Federal and State programs are implemented to meet
the Act's requirements. Under Section 402 of the Clean Water Act, all point source discharges
(see Section 2.1 for definitions) of pollutants to navigable-tyiaters of the United States must be >•-•
permitted under the National Pollutant Discharge Elimination System (NPDES), NPDES , --
permits are issued by EPA or authorized states. In Region 10, Oregon and Washington are"
currently authorized to implement the NPDES program, and these states issue NPDES permits
that are subject to EPA review. EPA is responsible for issuing NPDES permits in Idaho and
Alaska.
^
**
Figure 1 shows the NPDES permitting process. The process is summarized in the
following text. Readers are referred to the U.S. EP&WPDES Permit Writers'Manual (EPA
.!<&§!* *• " f
1996) for more information. The primary reguteftibiis(«f(Mi|^ped by EPA to implement and
administer the NPDES Program are found ia40 CFR'Pa
The NPDES application process formally begins upoijSabinission of the application to
EPA Region 10 and proceeds through a numberx>f steps retired by 40 CFR 122. Prospective
applicants are encouraged to correspond witfe and, if appjjfpriate, meet with Region 10 staff prior
to preparing and submitting the afplication. Application"requirements are prescribed in 40 CFR
122.21, butjlii always beneficial if an open
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Identification and authorization of the discharge.
Effluent limitations. Effluent limitations are restrictions on the quantity, rates, and/or
concentrations of pollutants that are discharged from point sources. Effluent limits are
either technology-based (based on technology-based effluent limitation guidelines) or
water quality-based (based on water quality standards). In determining the need for
effluent limits, EPA assesses the applicable technology-based limits and the potential
for exceedances of water quality standards. Because data supplied by the permittee is
critical in developing effluent limitations and most of the permit writer's time is spent
in developing effluent limitations, the processesrlar-developiiig^eilBeirt limitations are
described in Sections 2.3 (technology-based limits) and 2.4^watei^uaBty-based
permitting). #>.
?<*.
4'
Monitoring and reporting requirements. Permftteles are required to monitor Waste
streams and receiving waters to allow EPA (and/or states) to monitor changes in water
quality, to evaluate wastewater treatment efficiency^ ao&determine compliance with
permit limits. _ y
*iX
" /? /f, '
Special Conditions. Conditions arexdevel(g)e^|^^upplementeffluent limitations.
Examples include best management practices (iBMPs), additional monitoring activities,
ambient stream surveys, etc. "" / 1 '-',
#'
:-'-A , "
Standard Conditions. Prj||stablishe
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Receive Application
Review Application for completeness and accuracy.
Request additional information as necessary.
Using application information and other data sources,
develop technology-based effluent limitations
Using application information and other data sources,
develop quality-based effluent limitations
Compare water quality-based
effluent limits and technology-based
effluent limits for each pollutant.
Choose more stringent 6fthe two.
Develop monitoring requirements for each pollutant
Develop special and standard conditions U
Prepare draft permit and;
perm
Issue public notice for the
Respond to com
and issu
e draft permit
al permit
Consider other applicable
regulations [e.g. ESA, § 401
certification, CZMA]
Implement Permit Requirements
Source: U.S. EPA NPDES Permit Writers Manual
Figure 1. NPDES Permitting Process
November 1999
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Before EPA can issue a permit in Idaho or Alaska, the state must certify that the discharge
authorized in the permit will comply with state water quality standards (this is known as a 401
certification after the CWA section that requires it). Section 2.3 discusses state water quality
standards provisions important to permitting.
EPA is not obligated to issue an NPDES permit to any mine operator. EPA may reject a
permit application if the agency believes that discharges would not compjy with Clean Water Act
provisions and/or anticipated permit conditions. For example, EPA woill not issue a permit to
facility where proposed discharges are not expected to meet technology- or water quality-based
effluent limitations (see 40 CFR 122.4 Prohibitions). 5 ' / ?-f /
states early in the planning process. This will assist in evaluating options for wastewater
management practices and identifying NPDES information needs.
2.1 When is an NPDES Permit Needed?
As noted jn Sectioii^^^DES permits are required for any discharge of a pollutant from
a point source to waters of til^^^The term "point source" is defined very broadly under the
Clean Water Act, in part becaus^M^been refined through over 25 years of litigation. It means
"^ '••: %g KM . '*&^*J °&Lpi)S *•''
any discernible, confined and discreterconveyance, such as a pipe, ditch, channel, tunnel, conduit,
discrete fissure, orcontainer (see 40 CFR 122.2). Similarly, the term "water of the U.S." is
defined very broadly under thesClean Water Act and through years of litigation. It means
navigable waters, tributaries to^navigable waters, interstate waters, the oceans out to 200 miles,
and mtrastate waters which areused by interstate travelers for recreation or other purposes, as a
source of fish or shellfish sold in interstate commerce, or for industrial purposes by industries
engaged in interstate commerce.
f. • •
.'•*
Given these broad definitions, nearly any discharge from a mine could be considered a
point source, rfii general, three discrete categories of discharges from mining operations require
NPDES permits: process wastewater, mine drainage, and storm water. Definitions of each are
provided in Table 1. NPDES permit applicants are encouraged to communicate with EPA or an
authorized state to determine how to categorize discharges and to discuss the permitting process.
November 1999
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Table 1. Categories of Discharges from Mines
Process wastewater
"...any water which, during manufacturing or processing, comes into
direct contact with or results from the production or use of any raw
material, intermediate product, finished product, byproduct, or waste
product." (40 CFR 122.22)
See Section 2.3 for discussion of effluent limitation guidelines applicable
to process wastewaters. ,*-. :
Mine drainage
"...any water drained, pumped, or siphoned from a mine." (40 CFR
440.132) [See Table 3 for definition of "mine."] '- ,
*„_ ' ' f!*S
See Section 2.3 for discussion of effluent limitation guidelines applicable
to mine drainage. » ^
Storm water (associated
with industrial activity)
iroducts
I and si
. For the
the storai
"... the discharge from any convejrjance which is used for collecting and
conveying storm water and whichiWflitectly related to manufacturing,
processing or raw materials storage areaSjat an industrial plant. ...[T]he
term includes, but is not limited to, stcfctti'vfcat^ discharges from industrial
plant yards; immediate access roads and rail lines used or traveled by
carriers of raw material^flaannfactured produces, waste material, or
byproducts used or^lle3iA%-^e^cility; material handling sites; refuse
sites; sites used f^llSe applicadpa,,or.
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the facility is a "new source". "New source" is defined as any building, structure, facility, or
installation from which there is or may be a discharge of pollutants, the construction of which
commenced after promulgation of applicable new source performance standards (see Section 2.2
for discussion of new source performance standards). Specific criteria that EPA uses to
determine whether or not a discharge is a new source are in 40 CFR § 122.29. In general, most
new mining operations are defined as new sources. Construction at existing facilities may
represent a new source depending upon the age of the facility.
-"*• 4
If the facility is determined to be a new source, 40 CFR»122.29(c) provides that the
issuance of the NPDES permit is subject to the environmental review requarenjents of NEPA,
and thus to EPA's NEPA regulations at 40 CFR Part 6 Subpart F. In cases where t^EPA applj
EPA expects the permit applicant to begin the environmental review process bypteg&n^jjjis
Environmental Information Document (EID) with the NPDES permit application (see Section
4.0). In preparing a draft new source NPDES permit, the administrative record on which the
draft permit is based must include the EID prepared by the applicant, the environmental
assessment (and, if applicable, the FNSI) prepared by EPA, and/or fee ^environmental impact
statement (EIS) or supplement, if applicable. In addition, public notice for a draft new source
NPDES permit for which an EIS must be prepared cannot take placenatM the draft EIS is issued
[40 CFR Part 124.10(b)]. „ _v -
2.2 Technology-based National Effluent Limitation Guidelines
»• ••-•' / «
Section 301(b)(2) of the Cleaa-Water Act requires technology-based controls on effluents.
These technology-based contplslare established in effluent limitation guidelines (ELGs).
Section 304(b) of the Cleam^aip- Act requfee^EPAto promulgate regulations providing ELGs
that set forth the degree •df^M^reduction' attainable through the application of the "best
practicable;control available" (BPT) and the "best available technology
econonu'cally achievable" industrial dischargers (new sources), §§304(c) and
306 require EPAtxfprbmulgate Mrie^s©lirce performance standards" (NSPS) based on "best
available demonstrated technology." */To move toward the Act's goals of eliminating the
discharge of all pollutantsrexisting industrial discharges were required to achieve these ELGs by
specific dates: BPT ELGs by 1977 and BAT by 1983. All new sources are required to meet
NSPS from their inception. "r
&••
The current ELGs for the ore mining and dressing industry were promulgated by EPA in
1978 (BPT) and 1982 (BAT and NSPS). The ELGs for the ore mining and dressing industry are
found at 40 CFR Part 440, which applies generally to facilities classified with Standard Industrial
Classification (SIC) code 10; this includes and is limited to the mining and milling of
metalliferous ores (this discussion does not include placer gold mines, for which the ELGs at 40
CFR Part 440 Subpart M were promulgated in 1989 and take a somewhat different form than the
rest of Part 440). Other than gold placer mining, EPA has divided the ore mining and dressing
November 1999
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category into 11 subcategories based on the type of ore mined and milled. The subcategories for
which EPA has established ELGs for one or more types of discharges are shown in Table 2.
For the various subcategories, there are ELGs for two types of discharges: "mine drainage"
and "process" wastewater. The latter generally includes effluent from mills (such as water
contained in tailings) and other concentration (or, in RCRA terms, "beneficiation") operations,
such as dump and heap leach operations. See Table 1 for definitions of mine drainage and
process wastewater. The ELGs specify numeric limitations, and contain various applicability
conditions and exemptions. For certain mills in some subcategories, the NSPS ELGs allow no
discharge except in net precipitation areas, where so-called "zero discharge" facilities may ffr
discharge only the volume of water that represents the excess of annual precipitation over annual
evaporation. Under certain conditions, Part 440 provides a. "storm exemption" from applicable
ELGs for discharges from'qualifying facilities in all subcategories. Tables 2 and;3 provide an
overview of the requirements of Part 440. Table 2 shows tfaetvpes of ELGs that have been
promulgated for the various subcategories and the types of limits established for these categories.
Table 3 presents certain definitions (e.g., of "mine") as well as a summary of the storm
exemption.
It is worth noting that ELGs are established TOT only a limited number of the pollutants that
are likely or known to be present in the discharge from metal mines and mills (for example, the
ELGs establish concentration limits for oily one or a few%ifital pollutants, although a suite of
heavy metals may generally co-occuraapischarges). Compliance with the ELGs is intended to
ensure that other metals present in the Sischarge are adequately treated. The ELGs' technology-
based concentration levels are considered the baseline fair .discharges.
A Se
limits, n
this fact i
tic distinction is also worth noting. Although the ELGs establish technology-based
lations -pequire the use of any particular technology, and
JJsrther, the ELGs require that discharges achieve at least a
ology on which the limit is based.
Any
incorpo
s and conditions that are specified in the ELGs must be
it. Therefore, it is critical that permit applicants adequately
discharges so that it can be determined which ELGs apply.
into the'.
charaejirize their operat|
ing a water balanii aSH maintaining proper water management are critical to ensuring
ccMfliance with the "z^6 discharge" provisions of certain of the ELGs. Water balance issues
scussed in morejlliail in Appendices A and E. As noted throughout this document, early
ation with Jg|M is strongly recommended. With the advent of the storm water program
Itation with EPA to ensure discharges are correctly characterized has become
11
November 1999
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Table 2. Industry Sectors and Types of Applicable Limits 40 CFR Part 440
Industry sectors covered by subparts
Subpart (Subcategory):
A Iron ore
B Aluminum ore (bauxite)
C Uranium, Radium, and Vanadium ores
D Mercury ore
E Titanium ore
F Tungsten ore
G Nickel ore
H Vanadium ore (when mined alone)
I Antimony ore— reserved
J Copper, Lead, Zinc, Gold, Silver, and
Molybdenum ores (except gold/silver
placer, which is in subpart M)
K Platinum ores
Types of limits placed on discharges
Subparts A, B, C, D, E, F, G, H, J, K: Numeric limits on
mine drainage. '
^ „•;*&.•"
Subparts A, C, E, F, G, H, J, K: Numeric limits on
process waste water discharges 'from certain mills
Subparts A, C^D, J: Zero discharge aH0wed from certain
mills except, if precipitation exceeds (evaporation op
annual basis. Such facilities may dischargelhe "•>-
difference (aet precipitation) and dischargfes'iOB^t meet
mine drainage limits.
~ ,"•> ' Ss
Subpart J: Zero cfJseJjzp^e allowed from certain mills,
except that discharge jnia^flfeallo wed if contaminant
buildup in recycle w^ter interferes with ore recovery;
, |W$ requfes operator to-^^fe such a demonstration.
," - "- 3^
Table 3. Selected Definitions and Provisions in 40 CFR Part 440
.'.:•> t/ ',*
Selected Definitions , *'* ^
/
§440.132 „, ,'",
"Active mining area" , '
"a place where work or other activity related to the extraction, removal, or recovery of metal ore is being
conducted, except with respect to surface mines, any area of land on or in which grading has been completed
to return the earth to desired contour and reclamation work has begun."
"Min<»" "*'%• • :--:J-
-------
mixed, for example) affect the regulatory classification and thus the applicable standards and
requirements.
For discharges or pollutants not covered by the ELGs, EPA uses Best Professional
Judgement (BPJ) to develop technology-based limits, hi addition, when technology-based limits
will not ensure compliance with applicable water quality standards for the receiving waters,
permit writers develop more stringent water quality-based limits (see section 2.3).|fp
< A „
I *
Information on implementation of ELGs in permits can be found in:$u%Permit Writers
Manual. More information on the development of ELGs for the ore minmg^Midressing industry
is found in The Development Document for Effluent Limitations Guidelines-a^d Standard for the
Ore Mining and Dressing Point Source Category (EPA 440/1 -82/061). - <
5, "" / •>
2.3 Water Quality Standards and Water Quality-Based Permitting
i. >
\ f •"
In addition to the technology-based limits discussed in tnejpre'vious section, EPA evaluates
proposed discharges to determine compliance with Section 301(b){l)(C) of the CWA. This
section of the Act requires the establishment of limitations in permits necessary to meet water
quality standards. In deciding whether or npfwater qiAty-based effluent limits are needed,
EPA first determines whether the discharge would cause, nas the reasonable potential to cause, or
would contribute to an excursion of water.quality criteria. If a "reasonable potential" exists, then
water quality-based effluent limits are calculated for that parameter. The permitted effluent limit
for a particular pollutant will be the^more stringent of either the technology-based or water
quality-based limit.
Wher^here is a "reasonable potentiaFVEPA also develops water quality-based effluent
limits fq^^ttilffluenf^icily (WET). WET is defined as the total toxic effect of an effluent
a toxi^ity test WET is a useful parameter for assessing and protecting
against qual^e^BSfd^by the aggregate effect of a mixture of pollutants in
the effluent. water ||ial^-based effluent limits according to the guidance in
WaW'Quality-Based Toxics Control (EPA 1991; also called
the 'TSQpr More on water quality-based permitting can be found in the
Perm^mriters Manual^
13 November 1999
-------
Yes
Total Discharge, inducing
sfcym water runoff, subject to
40CFR440
Do Discharges from waste rock or
cvertuden piles ojrrbinewrth
"nine dnainag^?
Is there a dry weather point
source discharge from the pile?
Indvidual pemrit required to
dscnaige (include BPJ
technctooytesedlinits)
\
No
Coverage tentatively allowed
under mJti-sector general
storm water pemrit
IJrrptementBvFte
2. Initial screen
3. Twice yearly monitoring tor metals
fife pollutants dscharged at
levels well below benchmark
threshold values?
Yes
Yes
Would the dscharge cause or
contribute to a wster quality
standards violation?
Indvidual permt required to
dscharge (include water
qualr^basedlinrits)
No
No
No
Indviduai psniit required
to dscharge (include BPJ
tEChnotogy^asedlirrits)
underan
indMduaJ
M=DES pemrit
Yes
N
Discharges solely composed
of storm water covered by
mJrJ-sector general storm
water pemrit
Figure 2. Example of Discharge Classification Depending on Wastewater
Source and Management
14
November 1999
-------
Information used to determine the need for and to develop water quality-based effluent
limits includes:
• Applicable receiving water quality standards
Characteristics and variability of the effluent
Characteristics and variability of the receiving
Where appropriate, dilution of the effluent in tip1receiving.4$siel
Because the receiving water quality standards are
effluent limits, a brief discussion of water quality stand
Various provisions of water quality standards are also di
loping water
f
ixing zones is presented below.
in Appendix B and D.
Water Quality Standards Under Section 303(c) of the Clean Water Act, States are required to
develop water quality standards to protect ttietspkity of water, and serve
the purposes of the Clean Water Act. development of water quality
standards are at 40 CFR Part 131. All 50 standards that EPA
jfg&jiyg* J?-"-''f? ^^^^^^^^^^^^^^^-".^^.~- -s "
has approved.
EPA has found that correctlv^plntiryin^pplicable jpter quality standards often poses
significant challenges for mine Sinjplnany projects will include direct or
indirect discharges to surface^w^fe, standards is essential to
environment and whether there is a need
Designated
designated
propagation
different u
determining
for wai
impacts
will be met.
onitoring programs and evaluation of potential
towards being able to determine whether standards
three major components:
ater bodies in a State are classified based on expected
)ical designated uses include public water supply, recreation, and
ish and wildlife. Different segments of a water body may have
This is important because both impact predictions and water quality-
based ef8iiht limits must consider downstream uses. . •
fr Quality Criteria: Section 303 of the Clean Water Act requires states to adopt
Criteria sufficient to protect the designated uses for State waters. These criteria may be
numeric or narrative. Numeric water quality criteria are typically expressed as levels,
constituent concentrations, or toxicity units. Narrative criteria are statements that
describe water quality goals, e.g., "free of objectionable color, taste, or odor" or "free
15
November 1999
-------
from toxics in toxic amounts." EPA requires States to develop mechanisms to
implement narrative criteria. For water bodies with multiple designated uses, multiple
criteria also apply. The most stringent of the applicable criteria is used to develop
water quality-based effluent limits.
Of note for mining sites is that water quality criteria for some metals are .hardness
dependent. Also, some state water quality criteria for metals are presented in different
forms (total, total recoverable, or dissolved). However, NPI)ES regulations require
that permit limits be expressed as total recoverable. WhereJhe criteria are different,
EPA uses default translators to translate between total and dlissolvpd, £PA uses
default translators unless the
(see Appendix B).
Anti-degradation: Each State must adopt an aM-^egradation policy. Stall' policies
must incorporate three components. First, existmgjl|f must be maintained and
to protect designated
tion is shown to be
not available.
may not be
protected. Second, where water quality is higte
uses, that quality must be maintained and protected unless
necessary for social and economic rea^^pgiArther alte:
Third, waters that are designated
degraded. jffP' ^
jjf /? ** *
Mine operators should initially obtain the applicable State water quality standards and
regulations. These can be obtainedMirectly frop State agencies. Most are also now available
from State government websites jta'frie Internet Each State must review its water quality
standards every three years,j|ltrJp|h more-fiequent-changes to standards and regulations are
common. Operators mus^«tta*the most recent standards and remain up-to-date on changes
j£ -* ^^^^^^^?*^^^^:^ ' ^^
throughout thJpermittirig^ci^p.isThis further emphasizes the need for frequent communication
with State agency personnel aatt^pate potential standard modifications that could affect
project planning and evaluation*
Mixing Zones. Mixing zofles^allpw for concentrations of pollutants to exceed water quality
criteria in small areas imm^3ktely around discharge points prior to full mixing of effluent and
the receiving waters. Undef"the Clean Water Act, States have the authority to determine whether
they will allow mixing zones and under what conditions. As such, each State has different
mixing zone provisions. The sizes of mixing zones are often determined based on low flow
stream conditions?i.e.^ when the least dilution is available in the receiving water. In addition,
available dilution is dependent on background constituent concentrations. A discharger must
apply to the appropriate state agency for a mixing zone and the state must certify the mixing zone
for EPA to use it in developing permit limitations. A mass balance, modeling, or other mixing
zone assessment is generally required to support a mixing zone application. In addition, some
16
November 1999
-------
states may require a biological assessment to support the mixing zone. Mixing zones are
discussed in more detail in Appendix B.
Site-specific Criteria and Reclassification. States typically have provisions for establishing site-
specific criteria for individual constituents in a specific water body. Such criteria often allow for
higher constituent concentrations than state-wide criteria because the individual water bodv can
1_ J **"•"$& J
oe demonstrated to achieve designated uses at the higher levels. Mine operators,|*lto elect to
pursue site-specific criteria will be required to provide extensive chemi(^gjnd4Sblogical testing
for the water body. They need to work closely with State agencies inai^S^ng any requests for
site-specific criteria. In addition, EPA needs to be consulted because slitfr|^||j£ criteria require
EPA approval since they represent changes to the State water qualit
state standards also require public involvement.
If a water body is not being used for a designated use, mine operators can pursmTre-
classification. The criteria under which a designated use may be removed are generally defined
at 40 CFR Part 131.10(g). Requests for re-classification "are also complex and require close
coordination with State agencies and EPA. In addition, 40 CFR Part 131.10(h) specifies where
designated uses cannot be removed. uses cabmfcbe removed if they are
•W!?,'Hlo,-.?bi' J
existing uses, unless more protective uses are
proponents si
the 303(d) list
uses. Ifthe
determinj^e status oi
requiiiinents.
Total Maximum Daily Load (TMDL). Sj
water bodies that are not meeting thejrjjjl'signed
the water quality criteria). Sectio
maximum daily loads) for these
of the amount of a pollutan
background&prces, inch
quires States to identify
e.g., water bodies that exceed
s to develop TMDLs (total
bodies. A TMDL is a determination
•om point, nonpoint, and natural
may be discharged to a water-limited
ions for point sources that discharge to the
>ns are developed into permit limits. New mine
,ce waters in the project vicinity have been included on
•easons for not attainting the water body's designated
ordination with EPA and State agencies is essential to
s and how the listing could affect NPDES permit
3^0 the development of effluent limits and conditions for discharges of
JPDES Program also includes provisions for control of storm water discharges.
As incB8a^3 in section 2.1, storm water associated with industrial activity includes any
discharges from conveyances directly related to manufacturing, processing or raw materials
storage areas at industrial facilities. On August 7, 1998, EPA published in the Federal Register a
further clarification of the applicability of the effluent guideline requirements for mine drainage
17
November 1999
-------
and the applicability of EPA' s storm water regulations to runoff from waste rock and overburden
piles (63 FR 42533-42548). Figure 2 illustrates how discharge from a waste rock pile may be
classified as either wastewater (i.e., mine drainage) or storm water. In summary, EPA's storm
water regulations generally apply to most storm water discharges from active mine sites where
the storm water discharges are not commingled with process/mill water or mine drainage. The
only areas exempt from the storm water regulations are those not directly associated. with the
active mining operation or potential pollutants (e.g., parking lots and office areas), *
v **. j •
Storm water associated with industrial activity at mme^tes may*be|> paaitted m two ways,
either by an individual facility-specific NPDES permit or|Hafgeneral
required or request to be covered under an individual periait. In some cas<
wish to consolidate regulation of process and storm watfedischarps under a
comprehensive individual NPDES permit. In other casej|fi|Ajplsa delegated
an individual permit to address facility-specific conditio^l^^gtoe necessity for
based limits for discharges to streams in certain cases.)
Unlike discharges of process wastewater where numerical
and/or water quality-based) are used to control
condition used to address discharges storm!
prevention plan or best management practis
ilities may be
lity may W
require
T quality-
its (technology-based
primary permit
:er is a pollution
permits for storm
a BMP plan. BMPs are
water discharges issued by EPA will include a requjiemi
defined in 40 CFR 122.2 as "... schedu|ls of actijpfies, prolplSSins of practices, maintenance
procedures, and other managementgractices taprevent orj^duce pollution of 'waters of the
United States.' BMPs also includiejtreatmen^&iuiremej^, operating procedures, and practices
to control plant site runoff, spillage or leaks;stadge.~or waste disposal or drainage from raw
and H ia-mffirenformation on development of a BMP Plan.
includeSiner requirements (such as monitoring) based on
of the permit writer and as necessary to ensure compliance
material storage.
Beyond die
the Best
with water quality standards.
Due torthe nature of 1|fe discharge (storm water) and the large number of facilities requiring
permit coverage, EPA hasi^Mioped general permits2 under which storm water discharges from
minin^facilities may be petniitted. A mining facility may be covered under EPA's Multi-Sector
General Permit for Mining Activities. The sections of this permit applicable to hardrock mining
facilities primarily include requirements for development of Storm Water Pollution Prevention
Plans which incorporate BMPs and monitoring provisions. As required by the August 7, 1998
has determined that certain categories of discharges, including many categories of
storm water discharges, are more appropriately controlled by a "general" permit rather than by
individual permits for each discharge. General permits are issued under the provisions of 40
CFR 122.28 and contain eligibility requirements as well as the specific requirements that
applicants must follow in order to have their discharges authorized under the permit.
18
November 1999
-------
Federal Register, storm water discharges from waste rock and overburden must be more
extensively tested as part of application submission and during permit coverage. This includes
sampling and analysis for metals.
The Multi-sector General permit contains some eligibility restrictions—that is, they
prohibit certain discharges from coverage under the permit (see, for example, PartJJ3.E(a) - (h)
of the Multi-Sector Permit). EPA (and authorized states) also have the discretiqnfo^cleny general
permit coverage to any discharge and require an individual permit. Thel^rejtie agency
recommends that mine operators coordinate with EPA prior;
request for coverage. -
2.5 Information Needs for NPDES Permitting
In order to issue an NPDES permit, EPA and authi
about the proposed facility and the anticipated discharges^
requirements are specified in the following sections o:
40 CFR 122.21(f): Information requirj
40 CFR 122.21(g): Applicatior
%
j
%
reqi
:es need extensive'imormation
in and information
40 CFR 122.21(h): Appli
process wastewater.
40 CFR 122.21(k)j
g dischargers.
Hes that discharge only non-
•r
for new sources and new discharges.
ments for facilities that discharge storm water
Table 4 i
of informa
states3.
these sections require to be submitted and the types
of the forms may be obtained from EPA and authorized
3 Forms also are available via the Internet at http://www.epa.gov/owm/npdes.htm or
http://www.epa.gov/owm/swlib.htm.
19
November 1999
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Table 4. EPA Forms Required for NPDES Application
Form number
Applicant
Information type
EPA 3510-1 (Form 1)
All new permits and renewals
Basic information on the facility,
location, owner, etc.
EPA3510-2C(Form2C)
Existing dischargers
<
Detail information on discharge sources,
locations, voluj||^ sources, treatment,
chasacterizai
EPA3510-2D(Form2D)
New sources and discharges
pHTlar to Fo
have to be eslimati
me data may =
EPA3510-2E(Form2E)
Discharges of non-process
wastewater
fnfonjgpfon on
"*" it, etc
EPA3510-2F(Form2F)
Storm water associated with
industrial activity (individual!
permit)
ation on storm water
.cteristics.
EPA 3510-6
Storm water associat
industrial activity^
permit) •*;.
T discharge(s) to be
ulti-sector general permit
Table 5, below, provides an overview ojpe types^Rnformation generally needed to
develop an NPDES permit. The table the Sgprce Book appendices where additional
information regarding information' needs The magnitude and extent of the
information/needs descri|»ed in Table 5 site-specific factors. Permit applicants
should consulfwith EPAvaod therce^ifying State agency early in the planning process to ensure
that appropriate data is collectedLJ]^^ particularly the case where the permittee applies for a
mixing zone, elects to develop site-specific criteria, or where threatened or
endangered spe6ies may fcfepresent
20
November 1999
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Table 5. Overview of Information Needs for NPDES Permitting
Information Type
Data Needs
Source Book Appendix
Description of wastewater
management and water
balance
Outfall locations and topographic
map
n/a
Identification of sources of
pollutants and sources of
wastewater ,'"
Appendix E and F
Hydrologic characterization,
water balance
Description of waste
treatment
Appendix
Effluent characteristics and
variability
Flow, chemical, physjplil an
WET characterization
*<>gmSii»,,
ppendix D
Receiving water
characteristics and variability
Flow, chemi
~ .f.:H
biologic;
Appendix B
Storm water characterization
Topo mjp?
ychemigp analysisjjphysical
ysis
Appendix D
Appendix E
Det
dilution
ssessment,
Appendix B
"resources
Icterization
Appendix G
svelopment of translators
Appendix B
Development of site-specific
criteria
Appendix B
21
November 1999
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3.0 DISCHARGE OF DREDGED OR FILL MATERIAL TO WATERS OF THE U.S. (SECTION 404)
Section 404 of the Clean Water Act addresses the placement of dredged or fill material into
waters of the U.S. and has become the principal tool in the preservation of wetland ecosystems.
Wetlands subject to regulation under Section 404 are those areas that meet the criteria defined in
the 1987 Corps of Engineers' Wetland Delineation Manual. Section 404 regulatory^authority is
shared between the EPA and the Corps of Engineers (COE or Corps). Section 4$f|a) establishes
the authority for the COE to issue permits for discharges of dredged orimatelials into "waters
of the U.S." at specified disposal sites. Permitted disposal s^ mus
§404(b)( 1 ) guidelines. In addition, §404(c) gives EPA
COE permit issuance at specified disposal sites. In prac||e, EPA
in rare instances where the proposed disposal site is of sftificant
and the COE cannot resolve disputes through the
Section 404(e) establishes that the Corps may issue
National basis for categories of activities that the Secrejpry
cause only minimal adverse environmental effects, andnave
effect on the environment. General permits
for public comment; the permits must be b
conditions that apply to the authorized act:
in §404(f) and conditionally include me Jp&structi
equipment. Applicants are strongly enejluraged;Ji?check
regarding general permits and spec^'conditiq:
propose to mine. Often there
Nationwide Permits.
EPA's
reverse •
power
where EPA
The process of issuiia
application typically conta
purpose; wetlands land <)ther "
its on a State, regional, or
deems similar in nature,
cumulative adverse
notice and a period
;uiQiphes and establish
quirements are established
f>ads for moving mining
local COE District office
effect in the area in which they
iposed, particularly with respect to
iividual plPpjrmit begins with a permit application. The
Jion describing the project, project area, and project
; U.S." that could potentially be directly or indirectly
^'niaintenance plans. The §404(b)(l) Guidelines
impacted; and mitigation, monitor
require the proponent^) dk||nstra^ffiat the selected project alternative is the least
environmentally damagj^gv^^cable alternative. It is important to note that the preferred
alternative selected duringjjljp1SFEPA analysis may not be the least environmentally damaging
practicable alternative. In addition, it should be noted that an alternative does not necessarily
have to involve only land'currently owned or controlled by the proponent. It can involve actions
(mitigation, for example) on land that could be easily obtained by the proponent.
It is thus important to avoid and/or minimize all impacts to wetlands and other waters of the
U.S. to the fullest extent possible. For proposed fill in 'special aquatic sites', which include
wetlands, there is a rebuttable presumption against the need to fill for non-water dependent
activities. A Memorandum of Agreement (MOA) between the COE and EPA, dated February 6,
1990, establishes the policy and procedure in determining the type and level of mitigation
necessary to comply with the §404(b)(l) Guidelines. The MOA sets 'no net loss' of wetland
22
November 1999
-------
functions and values as a national goal and defines the types of mitigation, for practical purposes,
as minimization and compensatory. Although compensatory mitigation is often the focus of
project proponents, from a regulatory perspective, avoidance and minimization should be the
focus of any project with the potential to impact wetlands and other waters of the United States.
A project description submitted as part of an environmental impact assessment or permit
application should clearly demonstrate how avoidance and minimization have beeniaddressed.
The COE evaluates the application based on requirements of the CWA, including the
§404(b)(l) guidelines, and based on comments received fromffublic notice reviewers, which
typically includes the EPA. Since the issuance of §404 pernMts'are subject toNJEP, A review, thfp
COE then prepares an environmental assessment or, in sonic cases, anEIS (or contributes to *
another agency's EIS as a cooperating agency) and issues a statement of findingTA peimit is
then issued or denied based on the finding. EPA may exercise M^veto authority*(§404(6))lit
anytime during the permit application process, or even prior to^ermit application being filed.
As was recommended above for NPDES permit aj^ica^^^t|^|highly advisable for
applicants for §404 permits to consult with the Corps appropriate
regulatory and resource agencies prior to facilitates a mutual
understanding of the resource issues early ipptification of alternatives
that avoid and/or minimize impacts and alkreffbr requirements and
design. This early consultation can sign|p!antly:
necessary- The Corps has released ajujjiber ofjigulator
recently published in the Federal jjjjiister on Jpirch 22,
be accessed through the COE :
information on COE regulatory g|§grams. Wetlands contains information related
to wetiandsJirniinoloev.
ft might otherwise be
(ance Letters that were most
>9 (61 FR 13783-13788). These can
, which also includes extensive
jthorit?
enforcement
primary authorij
operatic
.operat
^between the Corps and EPA: the Corps provides
*ing in violation of an approved permit while EPA has
rging dredged or fill materials without a §404 permit.
; NATIONAL El
IENTAL POLICY ACT
[The National Envjpnmental Policy Act (NEPA) of 1969 became law on January 1, 1970
|L. 91-190,42 tjflc. 4321 et seq.). NEPA serves as the basic national charter for
lental prj^fton. The law requires every federal agency to analyze and describe
ifntal effects that could arise from any action or legislation proposed by that
^provides for public participation through public notices of intent, the solicitation
Of ^SBffl'comment, and as appropriate, public hearings.
The general framework for implementing NEPA requirements is presented in regulations
issued by the Council on Environmental Quality (CEQ) which may be found at 40 CFR Parts
23
November 1999
-------
1500-1508. In general, the analysis and identification of the impacts of proposed federal actions,
and alternatives to those actions, are presented in environmental assessments (EAs) and/or, for
"major federal actions significantly affecting the quality of the human environment," in .
Environmental Impact Statements (EISs). Each of these terms is defined in CEQ's regulations
(40 CFR Part 1508) and refined in EPA's (40 CFR Part 6)). Over the past 25 years, the NEPA
framework for environmental review of proposed Federal actions has been substantially refined,
based on further congressional directives, action by CEQ, and an extensive body of case law.
Each federal agency has developed its own rules for NEPA com^^ftce^hat are consistent
with the CEQ regulations but address its own specific misjjpi'and pro^^nllctsities. EPA's --!
NEPA regulations are at 40 CFR Part 6.
4.1 EPA's NEPA Role
Under NEPA, EPA can serve as a lead agency, o
Most EPA decisions and actions are not subject to NE
leads to proposed EPA actions has been dete:
by NEPA. The major exception to this in thi
permits subject to new source performance;
issue such a permit is subject to NEPA, aftd thus
must be analyzed and documented iaan EA an
the lead or, more commonly, a cooperating ag<
Lead Agency. In some ins
subject to NEPA. In such
ices! delinea
oneofth
;, or reviewing agency.
taking process that
:alent to that required
ice by EPA of NPDES
The decision whether to
mpacts of permit issuance
EIS is required, EPA is either
ng the EIS.
1501.5, more than one agency's action is
ecomes the lead agency (or there are co-
PA, EPA generally serves as the lead
lead agencies). When art EPA action is subj
agency for proposed projects lha|jl^aot involve federal lands but that include actions over which
EPA has jurisdiction by law. Fo^^^pk, EPA would likely be the lead agency under NEPA for
a proposed project on private lands thjat requires a new source NPDES permit in a State where
EPA is the NPDES permpng authonty (see 40 CFR, Part 6, Subpart F). EPA can also serve as
a lead agency when tribal Mads and public lands are involved and where EPA's permitting
authority is broader in scope than another agency's. In addition, EPA is responsible for NEPA
review to support proposed legislation that significantly affects environmental quality as outlined
in'40 CFR 6.102(b). As described in 40 CFR 6.604(g), EPA may prepare NEPA documentation
using agency staff, by contracting with a consulting firm, or by using a 'third party agreement'
between the applicant*EPA, and a contracting firm. The 'third party' approach is most often
used for jarge mine projects where EPA is the lead agency. Under this approach, the EPA is
responsible for directing the contracting firm while the applicant pays the costs. The
responsibilities of lead agencies are outlined in 40 CFR § 1501.5.
Cooperating Agency. Federal agencies that have jurisdiction by law, but that are not lead
agencies, may be cooperating agencies upon request by the lead agency (40 CFR 1501.6). As a
24
November 1999
-------
cooperating agency, EPA participates in the scoping process and, upon request of the lead
agency, may assume responsibilities for developing information and preparing portions of NEPA
documents pertaining to the agency's areas of expertise. For example, EPA generally serves as a
cooperating agency whenever a mine is proposed on National Forest Service or Bureau of Land
Management land and requires that EPA issue an NPDES permit to construct and/or operate.
Depending on the types of expertise available to the Forest Service, EPA may play a significant
role in efforts to predict effluent quality and evaluate potential water quality impacts.
Reviewing Agency. Under Section 309 of the Clean Air Act;EPA is required to review and
comment in writing on all major Federal actions. The Agency reviews and prepares written Jv
comment on every draft EIS prepared by other agencies,' and assigns a rating to the % "
environmental impact of the proposed action and to the adequacy ^he draftlSS (see section
4.3). The comments are available to the public, and the^Sfees,,arld a synopsis of the comments
are published in the Federal Register. When EPA has mS^oncems about the impacts of the
proposal or the adequacy of the EIS, the Agency consultsxwiih the lead agency. EPA also
reviews final EISs, particularly ones where significantissues were raised in earlier comments.
EPA comments on final EISs, but not its ratings, are made available Jo the public and a synopsis
of comments is published in the Federal Register. f " , *** "'
If EPA's review of a final EIS deteraiinesjljiia proposeEaietieai is or'remains "unsatisfactory
from the standpoint of public health or or ^vironia^afel quality," EPA refers the matter
to the Council on Environmental QuaJigf in accoj^ance wit|t;4® CFR Part 1504.
art 6 outh
ts
rovi
leral
Lance d
nvironme
applicants, gr
sufficient in
w,,
4.2 EPA Requirements for E
40 C
environp
A ofthe
responsibili
hierarchy of
der NEPA and the CWA
Besses for identifying and analyzing the
ited actrJilPfnd for preparing and processing EISs. Subpart
jew of the Agency's purpose and policy, institutional
conducting reviews. Subpart A outlines EPA's basic
ition as follows:
ation Document (EID), which is a document prepared by
permittees and submitted to EPA. This document must be
enable EPA to prepare an environmental assessment.
EnvironmdKal Assessment (EA), which is a concise document prepared by EPA, or
by a cojafjlittor under EPA's direction, that provides sufficient data and analysis to
whether an EIS or finding of no significant impact is required.
Notice of Intent (NOI), which announces the Agency's intent to prepare an EIS. The
NOI, which is published in the Federal Register, reflects the Agency's finding that the
proposed action may result in "significant" adverse environmental impacts and that
these impacts cannot be eliminated by making changes in the project.
25
November 1999
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' cumulative
Environmental Impact Statement (EIS), which is a formal and detailed analysis of
alternatives including the proposed action, undertaken according to CEQ requirements
and EPA procedures. Guidelines that describe the focus and intent of EISs are
provided in 40 CFR 1502.2. EISs must provide rigorous, unbiased analyses of
potential impacts from the proposed action and its alternatives, determine|yhether
unavoidable adverse environmental impacts would occur, andxtescribejaly irreversible
and irretrievable commitments of resources. The treatment pjvi||pnental impact,
which generally receives close scrutiny, must consider
actions, and similar actions (40 CFR 1508.25).
Finding of No Significant Impact (FNSI),
action analyzed in an EA (either as proposed
measures) will not result in significant impac
review, and is typically attached to the EA
for the proposed action.
Record of Decision (ROD), which is
that describes the course of action to
of an EIS. The ROD typically includes a
will be taken to make the selected alt
Subpart B of EPA's.
subpart specifies the fo:
incorporated by reference
fes EPA
tions or mi
SI is made availlitte for public
the administrative record
it Federal Register
Agenc^pmowing the completion
;e mitigating measures that
ly acceptable.
Monitoring, which refersto EPA'sJpsponsibiljjl' to ensure that decisions on any
action where a final EISJs preparjgjire propjjip implemented.
led discussion of the contents of EISs. This
lecutive summary, the body of the EIS, material
Subpart C of the Procedures describes requirements related to coordination and other
environmental, review and consultation requirements. NEPA compliance involves addressing a
number of particular issues,; including: (1) landmarks, historical, and archaeological sites; (2)
wetlands, floodplains, important farmlands, coastal zones, wild and scenic rivers, fish and
wildlife, and endangeredspecies; and (3) air quality. Formal consultation with other agencies
may be required, particularly in the case of potential impacts to threatened and endangered
species and potential impacts on historic or archaeological resources. Section 5.2 discusses the
Endangered Species Act consultation process.
Subpart D of the Procedures presents requirements related to public and other Federal
agency involvement. NEPA includes a strong emphasis on public involvement in the review
process. Requirements are very specific with regard to public notification, convening of public
meetings and hearings, and filing of key documents prepared as part of the review process.
26
November 1999
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Subpart F presents environmental review procedures for the New Source NPDES Program.
This Subpart specifies that the requirements summarized above (Subparts A through D) apply
when two basic conditions are met: (1) the proposed permittee is determined to be a new source
under NPDES permit regulations (see Section 2.1); and (2) the permit would be issued within a
State where EPA is the permitting authority (i.e., that State does not have an approved NPDES
program in accordance with section 402(b) of the CWA. In EPA Region 10, Alaska and Idaho
do not have approved NPDES programs). This Subpart also states that t|e processing and review
of an applicant's NPDES permit application must proceed concurrentlyjplth eawronmental
review under NEPA. Procedures for the environmental revj^j)rocesi^|Mmed. Subpart F
also provides criteria for determining when EISs must be jppired, as ^|p;|Ses relating to the
preparation of RODs and monitoring of compliance withjpovisions i^|brpM;a|St!|^liin the jjp
NPDES permit. Additional information that is not reliant to theftew SoiliS^^^ean be
found in Subparts E, G, H, I, and J of the Procedures.
Of particular importance to new source NPDES peri
Environmental Information Document (EID). It is higjUrrec
with EPA regarding the scope of the EID as a well pre
process run much more smoothly. In general, addrel
EPA Region 6, EID Handbook, 1995):
An effective description of th
cause environmental change^ind wi
A concise description envi
an emphasis on which
lin to be the pro
its is preparing the
that applicants confer
£ the ensuing NEPA
[owing (adapted from
on project features which
ose features.
lental jMmng where the project takes place, with
med, very sensitive to change and/or
been designed and located, and will be built and
;e adverse environmental changes and to improve
essment of environmental impacts or changes.
Discussion ofjpnitliative environmental effects which would result from interaction
with other acuities in the same watershed, same airshed or same economic region.
&
f
;ion that necessary coordination regarding special resources has taken
certain Federal and state agencies (e.g., Corps of Engineers, U.S. Fish and
Service, State Historic Preservation Officer).
Section 6 provides guidance on information needs related to NEPA analyses.
27
November 1999
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4.3 When is an EIS Required?
The determination of whether or not an EIS is required is important as it impacts the nature
and extent of data that needs to be collected and analyses that need to be perfoimedpfo determine
the environmental impacts of a proposed project (and project alternative^^ NErfrequires that
an EIS be prepared for "major" Federal actions "significantly of the human
environment." Generally, the determination of the need foraWEIS hin|
proposed action would result in significant adverse impacts!
EPA's procedures provide general guidelines an*
determination (40 CFR 6.605). General guidelines are
• EPA shall consider both short- and long-te:
beneficial and adverse environmental imp
• If EPA is proposing to issue a num
time span and in the same general;
programmatic EIS. In this casgpihe broi
be addressed in an initial conj^hensiv^locunii
prepared to address issues associated^!!! site-
/
EPA's specific criteria for preparing
found in 40 CFR 6.605(b):
and indirect effects, and
!FR§ 1508.8.
l>
;rmits within a limited
consider preparing a
.cts of the proposals would
e other EISs or EAs would be
ific proposed actions.
new source NPDES permits are
Tfaenew^sourcemEL induce or accelerate significant changes in industrial, commercial,
agrlcuhurai^or residential land use concentrations or distributions, which have the
potential for significant 'effects. ^Factors that should influence this determination
s % K
include the natare. and extent of vacant land subject to increased development pressure
as a result of tfieiiew source, increases in population that may be induced, the nature of
land use controls iajthe area, and changes in the availability or demand for energy.
The new source will directly, or through induced development, have significant
adverse effects' on local air quality, noise levels, floodplains, surface water or ground
water quality or quantity, or fish and wildlife and their habitats.
Any part of the new source will have significant adverse effect on the habitat of
threatened and endangered species listed either Federally or by the State.
The new source would have a significant direct adverse impact on a property listed or
eligible for listing in the National Register of Historic Places.
28
November 1999
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Any part of the new source will have significant adverse efforts on parklands,
wetlands, wild and scenic rivers, reservoirs or other important water bodies, navigation
projects, or agricultural lands.
uncertain risks
'ederal, State, or local law or
The determination of significance can be challenging. CEQ provides some guidance in the
form of a two-step conceptual framework which involves considering the context for a proposed
action and its intensity (40 CFR 1508.27). Context can bej|j|idered at several levels, including.
the region, affected interests, and the locality. Intensity '||fers to the severity of the impact.
CEQ lists a number of factors to be considered when juijthg severity, including;
Effects on public health and safety
Unique characteristics of the geographic
The degree to which effects are likely to^
The degree to which effects are
Cumulative effect of the acti
Whether the action wo
regulation.
The,
Potenti
and they
degraded by ri
contribute to
EPA earl
EIS. SiHion 6 describ
justry ca^^^^P^articularly difficult to assess significance.
kthey often are delayed in time from the permitting action,
|ddition, impacts may occur in environments previously
snvironments where naturally occurring pollutants
Again, it is essential for applicants to coordinate with
ss to aetermine the data needed in order for EPA to prepare an
information needed for EISs on new mining proposals.
• Act (CAA) provisions apply to a wide range of emissions sources from mine
sites, including stack/point sources and fugitive sources. Fugitive emissions are generally
defined as sources that are not easily controlled (e.g., conveyors can be controlled while open
piles cannot). CAA requirements are generally applied through several different types of
programs. These requirements can be described by three categories: (1) new source permits,
29
November 1999
-------
including prevention of significant deterioration (PSD) and non-attainment permits, (2) new
source performance standards (NSPSs), and (3) State Implementation Plan (SIPs) requirements
for non-attainment areas. Title V of the 1990 CAA Amendments provides for consolidation of
different CAA requirements into single facility permits. EPA's permitting authority is generally
limited to "major" sources. States generally have exclusive permitting authority under CAA
Section 11 OA(2)c for minor sources. Beyond permitting, EPA must evaluatejcxjmpliance with
applicable air quality requirements for all new or modifiedjgjaifces assocfale^wi|h proposed ^
actions that are subject to NEPA. jP*' Jf VfC
Where an operator proposes a new point source o:
source, the entire facility must be reviewed for air qualf
to major and minor sources. Major source determinatio:
parameters from point sources, including: NOX, SO2, C
facilities are major sources if they emit more than 250'fes per1
Comparison of source emissions with these threshd^^lues incl
provided by proposed control measures.
threshold values for the six parameters and
dific^hs to an existing point
. Separate requirements apply
on the emissions of six
leulates, and lead. Most
of these pollutants.
d reductions to be
T at least one of the
There are two categories of new source reviews/perrn|^^pD analyses/permits for
facilities in attainment areas, and non-attainment analyses/If rmits for facilities located in non-
attainment areas. Non-attainment is measured'flirough capipliance with the National Ambient
d& &( ^s'^W
Air Quality Standards (NAAQS) for the sixpbllutants/m facility in a non-attainment area may
undergo a combination of bpth PSD and non-attainment analyses: PSD for pollutants that are
achieving-anibient air qu^6^^dards and iioa-aftainment analyses for specific pollutants that
are causing the I
^ •
PSD requirements include ihe usenxf Best Available Control Technology (BACT) for all
emissions sources, stick/point source emissions and fugitives. In addition, total emissions from
a site must not cause exceedances of NAAQS. EPA ensures compliance with NAAQS through
pollutant "increments." The applicable increments for a site depend on facility location. There
are nationwide increments for "Class I" and "Class II" areas. Class I areas lie within 50
kilometers of federally protected lands such as National Parks. More stringent increments may
be established on an airshed-specific basis depending on background air quality and number and
types of sources. In general, facilities that only affect Class II areas do not present issues related
to BACT not, meeting the increments. However, facilities located within or that can affect Class
I areas often present difficulties, because the national Class I increments are very stringent and
individual areas can establish even more stringent air quality related values (AQRVs). Modeling
is used under PSD to determine compliance with Class I and II increments.
30
November 1999
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5.1.1 New Source Performance Standards
and unloading. Un
i"''**&yin«-'^"!«*1-
-.- ^^v^-s^ - -
BWd'i"
As noted above, the PSD and minor source programs address facility-wide air emissions.
Under CAA Sections 1 1 1/1 12, EPA has also established minimum national new source
performance standards (NSPSs) for emissions of certain pollutants discharged . fifim specific
types of industrial units and operations. This includes metal|c minera^ip^mg (40 CFR Part
60 Subpart LL) and non-metallic mineral processing (40 CjipBart 60^p^^0). Mineral
processing is generally defined as extraction and beneficij|pn operatio|p|ed with jjr
transport and beneficiation of ore, including conveyor blftransferj«|Ents,
•**r J
storage bins, thermal dryers, and truck and railroad lo
operations are excluded. The NSPSs include opacity all
point source. In addition, there is an opacity standard foil
containment systems.
5.1.2 Specific Sources
Table 6 summarizes the applicability
sources at mining operations, generally
emissions, and mobile or stationary so
matter limits'each
matter that escapes from
*
Act^Bgrams to individual
"ssions are fugitive or stack
Table 6.
sion Soirees at Mine Sites
Source
Appli
uthoriti
Overbi
Waste RoS
Tailings, and
Spent Ore
sources (vehicles); except for Hazardous Air Pollutants
authority to control fugitives unless there is a major
jw sources, can require BACT, LAERs, and other
eeded W|jpiiply with PSD/non-attainment requirements; emissions from
tailing's, asbestos mine wastes, and phosphate rock (radionuclides)
redbyNESHAPs
Weti
sj little or no CAA applicability
Fary CAA applicability is National Emission Standards for Hazardous Air
(lutants (NESHAP) requirements for asbestos and radionuclides emissions
delated to re-use of waste materials containing asbestos; phosphate rock containing
radionuclides; etc.
Chemical
Storage
For wet storage, little or no CAA applicability; for dry, considered fugitives as
discussed under waste rock, tailings, and spent ore above
31
November 1999
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Table 6. Potential Emission Sources at Mine Sites
Source
Applicability/Authorities
Ore Handling
and Piles
Open piles - fugitives; Covered storage piles/areas and c|
conveyor transfer points, covered storage areas, truck
covered by NSPS (opacity and particulates)'r:5*>
yojUiPpoint sources;
! unloading areas
Heap and
Dump Leaches
Process Ponds
Mine Pit
Mostly wet and not relevant; where dry,fugitives
Wet - little or no applicabilit
Major source of fugitive and vehicle emi
for off-road vehicles to be established u&rer
for vehicles - (1) national - subject to stationary
EPA authority largely dependanUMglfor/minor
- mobile source, exempted cons:
technology-based standards
current interpretations
itting as point source,
and (2) Region X
by EPA under NEPA.
Underground
Workings
EPA policy decision
and must be evaluated
uncertain how widej^pplied
lines are stationary sources
itted as point sources;
Blasting
Above ground -Jfeives,
ifground -jgfe underground workings
Vehicle Use
See mine pitsjilve, haul;
; alscyflBJor sources of fugitives
Construction
Exernj
applic
activity; SIPs typically have generally
lents (e^grfmust not cause nuisance)
jcovered under new source permitting, major/minor source
f effects also be addressed as part of permit modification;
iidered
Inactive/Aband
onedMines
L, ongoing activity should be same regulatory and
piirements as active operations; CERCLA actions exempted from
permittingifeut still must meet standards (PSD, NSPS, etc.)
Generators
.;--cj*i
Point sources, may bring some entire mine sites into major source requirements;
also lower major source threshold for PSD/non-attainment analysis may arise if
'greater than about 75 Mw
32
November 1999
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5.2 Endangered Species Act
The Endangered Species Act of 1973 (ESA) requires Federal agencies to "injure that any
action authorized, funded, or carried out by such agency is not likely to Jeopardize the continued
existence of any listed species or result in the destruction or adverse m6dlpcajion of critical
habitat of such species." The purpose of the Act is "to prp«iit:a meanl;^eftDy: the ecosystems,
upon which endangered species and threatened species dejjind may bep^^e|^;and "to If
provide a program for the conservation of such endanger!*! species^! threate^ej|is|3fecies. "
Section 7 of the Act, as amended, outlines procedi
conserve Federally listed species and designated critical
Federal agencies to use their authorities to further the c
7(a)(2) requires Federal agencies to consult with the Ut^ Fish
and/or National Marine Fisheries Service (NMFS^^^fter refe:
to ensure that they are not undertaking, authol
jeopardize the continued existence of listed
habitat. For example, EPA will consult 'the Se;
well as preparation of NEPA documenljlibn.
iteragency coopereflfeirto
Action 7(a)(l) requires
isted species. Section
fe Service (FWS)
ier as the Services)
actions likely to
mod^iydesignated critical
nee of NPDES permits as
The roles and responsibiliti
the Department of the Interior
Understandi. NMFS is
marine i
species
occur within a^
procedures.
1998).
so have
ic Senjies in imjjimenting the Act were described by
ie Depaj|j|ent ofGjferhmerce in a 1974 Memorandum of
Ible for that occur in marine environments,
such as'^^^ftlSid steelhead that migrate from freshwater to
of their life cycle. The FWS is responsible for listed
nes. If listed salmon and trout species (e.g., bull trout)
/'ices would be responsible for completing Section 7
ft jurisdiction over some listed species (FWS and NMFS
e Section 7 conSfBl|iii process is designed to assist Federal agencies in complying with
meJlct. Figures 3A andlpB describe typical steps in the consultation process. Most consultation
iertaken informaJUpf First, a general description of the proposed action and a formal request
ist of proposejlpluididate and listed endangered and threatened species potentially affected
n are submitted to the Services by the lead Federal agency. The Services
ft of proposed, candidate, and listed species and/or habitat that occur within the
jparea. Although the inclusion of candidate species is not required by law, the
Services consider candidates when making natural resource decisions. If no species or habitat
are present, consultation ends. If species and/or habitat are present and a project involves major
construction activity, a Biological Assessment (BA) must be prepared by the Federal Agency.
The BA identifies the project, summarizes the biology of the listed species, analyzes the impacts
November 1999
-------
of the proposed action, and determines if there is likely to be an effect (either beneficial or
adverse) on any listed species. The BA is then filed with the Services. If species and/or habitat
are present and the project involves actions other than "major construction activity," the Federal
agency must still evaluate the potential for adverse effects and consult with the Services. This
may consist of preparing a Biological Evaluation (BE) or other type of^jjort tojSvaluate these
effects.
'i:'x
•&?
If the BA or BE concludes that the proposed agency action "is 1L,
any of the T&E species, formal consultation with the Seif ices is required.
proposed actionJspiperservices.
icy action(s) is likely to
•sely modify critical
ake of a listed species.
listed species,
ogical Opinion (BO)
•ee possible conclusions
d existence of the species;
; or (3) is likely to jeopardize
a determination that the
ued exisjfhce of the species, reasonable and
Reasoifeble and prudent alternatives are
f, *•
consistent with the scope of the Federal
Formal consultation involves a more detailed
The formal consultation process determines whether a p;
jeopardize the continued existence of a listed species or
habitat. It also determines the amount or extent of ant
After collecting the best available scientific and co;
and reviewing the Federal Agency's BA or B
that analyzes the impacts of the proposed
are made in the BO: the proposed action
(2) is not likely to jeopardize the con
the continued existence of the speci
proposed action is likely to jeopa|ifee*the co:
prudent alternatives must be mckned in the,
alternative actions that canj^dpementedt'i
agency's action, that are ecorafpcally and tecjHpBgically feasible, and that the Services believe
would avoid jeopardy or aSfc^e^JBodificatioifto the listed species, or critical habitat,
respectively.. The BO may alSb^g^reasonable and prudent measures to minimize impacts
(i.e., amount or extent, or incident
,» y* *<* & &L,
Concurrent with planning for permitting and NEPA review, it is essential that proposed
mine operators work wilfa the lead agency and the Services to plan for ESA compliance.
Biological surveys need to fully address the presence of proposed, candidate, threatened, and
endangered species and/or their habitat. Potential impacts need to be considered in preparing
plans of operations and permit applications. The lead agency will be responsible for ensuring
that final plans of operations/permitted activities are consistent with the findings of the
Biological Opinion. Specific reasonable and prudent measures and alternatives as well as
monitoring requirements identified in the Biological Opinion may be incorporated directly into
NPDES of other permits and Records of Decision issued by EPA.
Non-Federal representatives (e.g., proposed mine operators) may participate in the informal
consultation process, including preparing draft BAs. The lead agency must designate such
representatives in writing to the Services. Regardless, ultimate responsibility for compliance
34
November 1999
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Federal
Action
Action agency requests or
prepares species list
Service prepares list or
concurs with list prepared
by action agency
<-YES-
, 30 Calendar Days
Major
Construction
Activity?
Service prepares list or
concurs with list
prepared by action
agency
Species/Critical
Habitat Present?
-NO ^
End
Consultation
YES
•NO
Species/Critical
Habitat Present?
Biological
Assessment [180
days for action
agency to complete]
NO^
Optional
YES
May affect species or critical
habitat?
/- QR.
30 Days for Service to respond to
agency Biological Assessment finding
YES
YES
Optional discussions
between parties resulting
in "no effect"
determination
/.NO
Likely to adversely affect species
or critical habitat?
Formal
Consultation
Required
-YES-
YES
Written
Service
Concurrence
^^
•s
^
End Informal
Consultation
Figure 3A. Informal Consultation Under the Endangered Species Act
35
November 1999
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Action Agency determines
proposed action may affect
listed species or
designated critical habitats
Action Agency
requests initiation
of formal
consultation
Within 30 days
notify Agency of
missing 50 CFR
402.14(c) data
Information
is complete
k-YES ^
Consultation
clock starts from
date of receipt
Data is
received and
complete
90 Days
Service formulates Biological
Opinion and incidental take
statement in conjunction with
Agency/Applicant
45 Days
90 Days
Review of draft biological
opinion by Action Agency and/or
applicant, if any
Delivery of final biological opinion and
incidental take statement to Action Agency
end formal consultation
Figure 3B. Formal Consultation Under the Endangered Species Act
.{USFWS and NMFS, Endangered Species Consultation Handbook, 1998)
36
November 1999
-------
with Section 7 requirements remains with the lead agency (e.g., assuring that draft BAs are
technically sound). More information about the Act and consultation process is found in the
Endangered Species Consultation Handbook published by the Services in March If 98. This
document is available from the USFWS website at www.fws.gov.
6.0 EPA EXPECTATIONS FOR MINING IMPACT ASSESS
As discussed in Section 4, EPA's primary direct responsibilities%
relate to NPDES new source permitting of mines under the CWA and associat
At the same time, many of the most significant issues regarding potential environmliSS Impacts
from new mining operations involve water resources, aquatic Mbjj|t, jurisdictional wetlands and
other waters of the U.S. Consequently, EPA expects appMcanti^wfeLe a thorough understanding
s$x&&' ^ s^^^^^^^^^^^i^^^s ^^ ^^
of the hydrological and aquatic environment in which liey work. The NEPA
review and CWA permitting processes will reqmrejjptpn. variety of data,
conduct different types of analyses, and develoj^^pipil^^ facility^^^^erational designs to
define potential consequences on water rescplbeT^K^^^ojE'the Jp>es of data, testing, and
analysis that may be required are given irj^S>les 7 through 10 in turn refer
to the technical appendices for more dejUls. A g|piral dis^tsSiii'of information needs related to
predicting impacts to surface waterjg^fiand wajpi and wetlands resources are presented in the
following sections.
6.1 Impacts to Surface
)und
surface wal
determine potS
meteorologi
phase
Info:
M,
:vents
and
wal
glogicai
ical
|ther andlo what extent their proposed project will affect the
at the mine site and within the watershed. To
/ill require collection and analyses of a variety of
regarding;
lee Table 7), preparation of operation phase and closure
0), and wastewater and storm water management plans.
discharge, precipitation, and the duration and intensity of
sto:
.cal to this process. This is because most proposed sites are
mountainous Jfoastal, or subarctic areas where there are significant annual and
.al variations in epnate that make it difficult to develop data sets that are representative
tistically sigjjpcant. To overcome the problems associated with high short-term data
;-term record. However, most sites are likely to be proposed in remote
;-term records of discharge and climate are unlikely to be available either for
of interest or for nearby watersheds possessing similar physical characteristics.
Consequently, in order to gather data for as long as possible, applicants should establish stations
to monitor stream discharge and meteorological conditions during the early stages of site
exploration. Information and analyses necessary to determining impacts to surface water and
37
November 1999
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ground water hydrology is discussed in the following sections and in more detail in Appendix A,
Hydrology.
6.1.1 Surface Water Hydrology
A. proposed mining project can impact the quantity and ^
altering natural drainage patterns and the infiltration/runof^^3tons
discharging storm water and wastewater; impounding wajief; changing
and losing stream reaches through mine dewatering; miidftg through sireairrii
plains; and by diverting, re-routing, and channelizing stfteams. Importantly,
activities have the potential to alter the equilibrium balaBcerbeCpfeen flow and sedrm^ttransport
? ','&;& ^
in streams (Johnson, 1997). Altering this equilibrium cau§ejy||||jm gradients, channel
*
water flow by
iershed;
r,of gainin;
d
geometries, channel patterns, and stream banks to adj
reflect new erosion and sediment transport characteri
disrupt aquatic habitats both upstream and do
tailings impoundments, mine pits and other fa
mining landscape can cause fundamental c
(O'Hearn, 1997). Consequently, appli
/^.ifssi
on the post-mining hydrological envirqjaaient.
Most applicants will be reqv
in order to predict impacts to
needs are summarized belos
ilium conditions that
Such changes can
ion of waste dumps,
features of the post-
istics of a watershed
the effect of these changes
that might
the project wi
the boundari
Characterize
interactions o:
;ical studies and a site water balance
.ese studies and their associated data
detail in Appendix A, Hydrology.
irovideTTbaseline from which to measure or predict changes
proposed action and its alternatives. In order to place
iihed, the study should have a scope that extends beyond
As part of the study, applicants should:
e and subsurface flow regimes and surface-ground water
mal or monthly basis. Identify critical low flow conditions.
m
vjji--
Distinguish the effects that any current or historic mining activities have had on the
hydrology of the project area
Determine the extent to which different physical variables within the watershed control
; hydrological processes
Prepare an analysis of meteorological records that describes the seasonal variability,
frequency, and intensity of storm events.
38
November 1999
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Table 7. Data Needs for NEPA Review and CWA Permits
Resource Area
Data Needs
Appendix
Climate
Average annual precipitation; Monthly precipitation i
distribution; Mean monthly temperatur^jJMean monthly'1
evaporation; Storm characteristics (pjgplation rates);
Orographic effects.
A
Geology and Soils
Lithology and mineralogy of rock^&ils, andjitluvial depost|sj
Rock unit distribution; Structural M^teg^acture distributiT
& characteristics; Alteration and i
vertical and lateral changes; Surface^
Topography and slopes; Soil cove^pept
ign, including
:elationships;
Surface Water
Hydrology
Watershed delineation; Flo
of special designation w
morphology, channel
relations; Stream fl|pr(ave
flows); Flood fregplncy; Pr
relations;
ition
transport
itical low
;bn/ runoff
ater usage.
A,B
Ground Water
Hydrogeology
Aquifer
of flow,
ele
ization (storage, direction
issivity); Water table
zones; Confining layers;
afrost thaw; Ground water
U!
A,F
Surface W
Ground Water
Quality
.Backgif
and ground water quality; Existing surface
ality; Relationship of surface water quality
A,B
Efflu
juality of effluents and variability of effluent quality
fe of operating conditions; Expected flow of effluent
fiability of flow over range of operating and climatic
Inditions
D
Delineation of wetlands & waters of the U.S.; Wetlands
classification; Designation of riparian habitat & corridors;
Narrative descriptions that include nature, extent, functions, and
value.
Aquatic
Fish and macroinvertebrate population and diversity data;
Aquatic habitat characterization; aquatic mammals and
amphibians; Threatened, endangered, or sensitive species.
G
39
November 1999
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Table 8. Testing Needs for NEPA Review and CWA Permits
Resource Area
Testing Needs
Appendix
Solid waste
characterization (e.g.,
Waste Rock, spent
heap leach &
Tailings)
Grain-size distribution; mineralogy, Total and sul§de sulfur
content; Acid generating potential; Aci&neutralizifig potential;
Kinetic test; leach tests; Total metakiJIoiifent; Leaeterte* . -
compositions; Tailings water compositions. ^ ,
Rock, Soils &
Sediment
Characterization
Proctor moisture/density; Atterb
Direct shear; Permeability; Total
generating potential; Acid neutrali
rain
i-size analysis;
:; Acid
leach tests.
.,«/- rr
> W,F
Water Quality
Characterization
Major cation and anion concen
(total and dissolved); pH;
Temperature; Total h;
Dissolved oxygen,
A,B,D
Hydrologic
Characterization
In situ hydraulic
studies; Aquifej
;s; Drawdown
The baseline study should
operation and considered alte;
requires characterization
as basin
demonstrate Mwieonstmct
runoff responsbsfto}
regimes and chl
capacity)
need to be defined. E:
streamreaches from
averai
raluate whether the proposed mine
rology of a watershed. This analysis
Dhological and other characteristics, such
conditions. In addition, applicants need to
aroposed mine and its associated facilities might alter
|me precipitation events. Impacts to seasonal flow
lei bed and bank erosion and sediment transport
sfreafpPdiversions, channelization, and altered drainage patterns
ace water discharge, and impacts to spring-fed wetlands or
ring activities should also be quantified.
** ,' Applicants must determine whether their proposed operation will result in discharges to
waters of the U.S.. An accurate assessment is accomplished by developing a thorough
uu
-------
closure). The site water balance is used to determine whether a proposed mine would have a net
gaining system that may require continual or periodic discharges.
Table 9. Preliminary Design Needs for NEPA Review and €WA Bplits
Resource Area
Preliminary Design Needs
Appendix
Mine Operation
Mine plan; Facilities layout.
Infrastructure
Road locations and construction;
storage; Borrow areas; Water ane
crospfS; Fuel
itewateiireatment i
Beneficiation
Mineral processing methodology;!
construction; Conveyance systems;^
stockpiles.
age; Facility
icentrate
Waste Disposal
Tailings impoundments and pileskWaste roclimispent ore
dumps; Overburden
Process Water
Management
Process water flow offfi; Stc
structures; water Milnces
ice
D,E
Storm Water
Management
Diversion
ss; Retention ponds.
Closure and
Reclamation
Best Mi
rir
lement'.
;vegetati^
^stabilization
leach neutralization and
iing and recontouring;
^Facility removal; Pit wall or
E,F,H
pre35|p$arological impacts and develop a site water balance are
10 recognizes that many mines proposed in
nortoexuwd central to be situated hi areas underlain by permafrost. In these
ternus, stream flow an(^^^^ation-infiltration-runoff relations vary seasonally due to winter
I. Applicants propjpng to work in these areas should give special consideration to their
ie hydrological chtecteristics and to seasonal variations.
41
November 1999
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Table 10. Data Analysis Needs for NEPA Review and CWA Permits
Resource Area
Data Analysis Needs
Appendix
Waste Rock &
Tailings Disposal
Impact
^^•^^^^^MMHAIMH
Surface Water &
Ground Water Quality
Impact
Predict short- and long-term acid generating pote
metals teachability; rates of seepage andjun-offjg
stability of piles, impoundments, and backfill
C,F
Statistical analysis of water quail
discharge composition; Estimate^
Projected effects of discharge on
quality; Estimated pit-lake water
of ground and surface water quali
ata; Estin
iposition;
surface water
ected likelihood
spill events.
Hydrological Impacts
Facility water balance; Design
model (e.g., HEC-1); Flow
development model; Gn
MODFLOW); Storn\
transport model; Djps'atering,
Changes in recha||e characiistic
i moc
A,H
>n curves;
>w model
ledimejaPIrosion and
'T
:overy;
Wetlands & Aquatic
Life Impact
Calculated jppseted
and valuejlptential i
populattejplthroughsll
aci
id type, loss of function
d macroinvertebrate
flow, and habitat loss.
B,I,G
6.1.2 Gt
•Hyt
^operatKi|
"^ MethfT
jact the availability and flow of ground water by
"dewatering operations; disrupting aquifers; locally
faltering zones of natural recharge (Brown, 1997). Mining
for ground water contamination by exposing aquifers and
A propo
locally lo1
removing confining
activities ulso create op
* •7p^"^!^IW^I'?' "^ "" ~J •*" ^ —•"•
puncturing aquitards. of ground water flow direction or reduction in the water table or
potentiometric surface cm potentially impact wetlands, aquatic habitats, and stream discharge
characteristics. M
Most applicants will be required to submit a detailed hydrogeologic study of the region in
which they are proposing to operate. This study and its associated data needs are summarized
below and described in detail in Appendix A, Hydrology.
The hydrogeological study should provide a baseline from which to measure or predict
changes that might occur as a consequence of the proposed action and its alternatives. It should
42
November 1999
-------
have a scope that extends beyond the boundaries of the proposed operation. As part of the study,
applicants should:
• Identify aquifers and confining layers and their vertical and lateral extej:
«l^ jd
• Determine the types of aquifers (confined or unconfined), ag|i|||rfaracteristics such
as hydraulic conductivity, primary and secondar^»osity,:lS|^^ffi^fficients, and
hydraulic gradient, and hydraulic communicat^Kf any, wSter or other
- * ^
ground waters
Characterize each confining layer and its ph)
ties
Determine the depth to water, the configuration^!table or potentiometnc
㣥 J.I- U J 1- J- J^l 4P"
surface, and the hydraulic gradient and flowwrectionipsfj
Where required, quantify the seaso:
Distinguish the effects that
hydrogeology of the project
water fifiilm permafrost terrains
Activities have had on the
Region 10 expects applicani
resources caused by water use
mines can deplete aquifers
wat
should
should
whether
flow, wetlan<|
ofgeotecj
impo
uni
di
effd
.ents, emi
lidated alluvial
ntial compaction.
stential impacts to ground water
Catering of surface and underground
: and discharge, and locally change the
jr these collected for hydrogeological studies
of the potential impacts of drawdown. This analysis
• levels or specific yield would be affected and
icing the potentiometric surface would impact spring
1 other ground water users. In some cases, an analysis
drawdown may be required to adequately design mine facilities,
foundations. For example, dewatering a comparatively thick,
at overlies an undulating bedrock surface, could cause
msolidation, and uneven surface subsidence. These effects could
the geotechniiJF stability of facilities such as tailing dams and the integrity of engineered
such as pond liners. Data collected during dewatering operations should also
rate at which the ground water system is expected to recover following
Hydrogeologic studies conducted in terrain underlain by permafrost will need to
characterize the conditions unique to this sensitive environment. Included are the seasonality of
ground water flow in the near surface environment, the depth of annual thaw, potential
connections between shallow and deep (below the permafrost layer) ground waters, the
43
November 1999
-------
importance of vegetative layers, and the potential for mining-induced thawing of frozen materials
(either by excavation of insulating vegetation or rock layers or construction of permanent
facilities such as tailings impoundments).
The hydrogeologic study should provide a basis for assessing the:
water regime following mining. This includes estimating the fate at wfiflSl
^^ ~& /• '^ij\ £$§J?~ '\- 'tfV "*-'•'
would recover and describing potential effects caused by the ;plmatiolgp
disruption of recharge zones (especially those associatedjiph confinedj
seepage waters from permanent mine facilities (e.g., laipps impoundments)
confining layers, the disruption of aquifer continuity, ai|f||he bajplilling of ml
1997).
V
"the ground
id water levels
,the
influx of
of
of storm water,
red to address during
'sed project is expected to
ould create short- or long-
emphasis on evaluations of
6.2 Impacts to Water Quality
W
Impacts to surface and ground water quality from
mine drainage, and process water. Two will
the NEPA review and CWA permitting prj
lead to a discharge of wastewater and whefler the
term impacts to surface or ground watepquality. pk
potential wastewater discharges becalusS once operfjlons have been initiated, discharges
often cannot be stopped or reducedj|ithe does nolmeet water quality standards.
Historically, the most problemati^ischarg^Kcur frgpflnajor mine components that are
exposed to the atmosphere^sitehjas mine dumps, tailings impoundments, and
leach facilities. Because to the elements long after mine closure,
the potential for the acid, cyanide, sediment, or other contaminants from a mine
site must be accurately analyi^^^A^ating the potential for long-term risk from waste disposal
practices is a difficult task, but ifis"Ofpomary importance to demonstrating compliance with the
CWA and in disclosing accurate irifotanation to the public. Factors associated with evaluating
long-term impacts include: ^?i>
jf V**? *> ?m&
« *y -93 ^ t ri Ax%&&
„«*# •> tr
Characteristics of waste rock, tailings, and other waste materials
Facility design and construction
-ir
sj • j .Beneficiation and processing methods
Local meteorological and hydrological conditions
Solid waste and wastewater management methods.
Closure and reclamation methods.
44
November 1999
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Determining potential impacts to water quality typically requires applicants to collect a
variety of data, conduct numerous geochemical tests, develop preliminary mine plans and facility
designs, and perform different types of data analyses. In general, applicants should anticipate
that they may be required to provide studies that characterize:
/a
• Background surface and ground water quality wjiiaitthe w;
proposed operation Jff ':f"
Background surface water hydrology and
of interest
Expected hydrologic, physical, and geoch
leach piles, and tailings impoundments, andHiher wl
following closure
Chemical compositions of procesj
effluent
drogeo
yaf waste rock piles, heap
|als during operation and
Effectiveness of rinsing,
employed for these faci
Each ojythese items
alizatigjif and closjie and reclamation methods
subsections.
ly impacted
ation associa
the conditions o
control
•*$g$r
;e,ancf treated and untreated
in Appendix
and 10.
analyzjjijlickground nn
ltd existing water quality in a watershed are discussed
zfera/l^pfg needs and data analyses are summarized in Tables 8
idix, applicants should employ robust statistical techniques to
icr constituent concentrations in different portions of a
"quantify the magnitude of seasonal variability in water quality
fithT high and low stream flow conditions, and evaluate water quality
Ighest risk (i.e., worst-case conditions). Adequate quality assurance and
demonstrated. For example, analytical methods employed must be
easure the parameters of concern at levels at or below the water quality
45
November 1999
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6.2.2 Regional Hydrology and Hydrogeology
The hydrology and hydrogeology studies described in Section 6.1 should provide data to
evaluate potential future water quality impacts. Applicants for NPDES £<^itsjiould develop a
surface water management plan and site water balance that algo can bejisll ;j^hen evaluating
potential water quality impacts.
6.2.3 Hydrology of Mines and Waste Facilities
Predictions of whether and when a mine or waste
acidic water or to release metals or other constituents an
facility, the compositions of these fluids, the compositiojpr<
are in contact, and the chemical environment in which'ffie flui
effluent flow rate and discharge composition
and ground water hydrology, effectiveness of
final unit construction and closure methods
variables that may be difficult to determi
applicants should employ facility desi
conservative estimates for acid
determine future impacts.
In general, the hydro!
more detail iiiyAppendi
-^E ' ^^ " ^ v"'
open pits and that jpder;
which lake fillHig.or undergfl
i i j r&i'-ate^-
knowledge of p^sprapK. grouni
can be used pi
•acility may beginHSj generate
the flow of fluids through the
ials with which the fluids
curate predictions of
racteristics, surface
•ound water controls,
um, and other
cess. Consequently,
and seepage and use
and leachate composition to
The long-term
ind described in Section 6.1, and in
ivide the likelihood that lakes will form in
^^SfW^--^1'
igs wilrflood when mining ceases. Although the rate at
.g is expected to occur can be estimated from
r, data collected during actual dewatering operations
if the expected post-closure conditions.
havior of waste rock dumps and tailings impoundments
on method, grain size and sorting of the waste materials,
depends on factors suchJ
secondary mineral formation^ and closure and reclamation methods (Blowes et al., 1991; MEND,
1995; Swanson et al., 1998). Predicting seepage rates can be difficult, especially for facilities
that are likely to be partially saturated, such as those located in dry climates (Swanson et al.,
1998), Generating acceptable model simulations is even more complicated for facilities
constructed in such a way that they are physically heterogeneous (e.g., discontinuous layers of
coarse and fine waste rock) (Swanson et al., 1998) or within which layers of secondary mineral
cements formed during weathering (Blowes et al., 1991). More detail regarding the prediction of
hydrologic impacts of waste rock dumps and tailings impoundments is provided in Appendix F,
Solid Waste Management and Appendix A, Hydrology.
46
November 1999
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6.2.4 Solid Waste and Materials Characterization and Management
Applicants will need to demonstrate that they have adequately characterized their waste
materials and the potential for these materials to contribute to dischargej|g surj^eewaters and
groundwater. Tests commonly used to characterize bulk chemical 'composition,
metals teachability, and acid-generating potential are s
described in Appendix C, Characterization of Ore,
many different tests available to determine leachability
single accepted way of interpreting test results, applie
regulatory agencies to enquire whether specific test m
sdin
jck, and I
acid-gejpisting
loulcjyflfnsult with
referred.
.d 10 and
.use there are
no,.41
state
representative of material
:ermining the number
tested samples
Applicants should demonstrate that the samples c
that will be produced during operations. There are no lit gui
of samples that should be tested. Recent studies su^M^that the
should be determined by the compositional materialHpErwill be disposed of
(Shields et al., 1998). Applicants are inherent to different
lithological units across the project area vs. heterogeneous
colluvium) and that may have been impjlted to weathering,
hydrothermal alteration, and minerajpliion. Ajjjpiicants wjjineed to consider how vertical and
lateral changes hi the intensity an^pple of mpjteralizatiojrarid host rock alteration affect the acid
generating characteristics and leachajfifty of easfrgeologic unit at the proposed mine site.
Because co
use inex
median
various li
characterizing
ositional va
visual
,tha
? equates J
(e.g.
f mineralogical variability, applicants can
Hie microscope) to quantify the range and
^>l©3s!I ^
i-neutralizing, and metal-bearing constituents in the
Countered. Testing programs can then focus on
; the compositional range identified for each rock type.
Forj
whichjplresent waste:
handflcl during the:
• representative <
gtions, it may be appropriate to formulate composite test samples
rerburden materials as they are likely to be excavated and
ration. It is important that composite samples be created in a
ic proposed operation.
ion
'ailings test should be taken from pilot-scale metallurgical tests representative of
fl be employed during full-scale operation. Applicants should test ore
re the range of ore grades that will be processed during the life of the mine.
Of particular concern to EPA and the public is the potential for waste rock, tailings, and
heap leach materials to generate acidity and release metals after protracted exposure to the
environment. Tests of several years duration conducted on mine materials indicate that
acidification may occur after periods of neutral drainage lasting one to two years (Lapakko et al.,
47
November 1999
-------
1998), even in the accelerated weathering environment of the lab. Applicants should recognize
that static acid-base accounting tests provide information only on the relative proportions of acid
forming and acid-neutralizing components in a sample and provide no information regarding the
rates at which these reactions are expected to occur. Information regarding the lattercan only be
obtained by kinetic tests that are conducted for a sufficiently long time. Kinetic tests typically
are conducted for 20-week periods; however, there is a trend|oward usinglonger test times
(Price et al. [1997] advocate 40-week tests) that would be vieifed favorably by Region 10.
'
The results of static and kinetic tests are particulaBpfeensitive^to the test method and
laboratory technique. EPA Region 10 encourages applfj|||ts to giiduct all tests using the same
test method and testing laboratory. In addition, stated in moist kinetic
test procedures, Mills (1998) points out that it is typical starting kinetic sample
and final leached product to be tested for static metals.
Mineralogical analyses also should be conducted on iMfse these data can
provide important constraints to assist the interpre|a|B^Mf test
Interpreting the results of leach kinetic tests is not
straightforward and there are no (see Appendix C). This
is because the conditions simulated by jP tests from the environment in
which wastes will be disposed and bjetuse manj^test methjpologies require that samples be
crushed or ground to particle sizes sigmfican|jpnner majiproduced by the mining operation
(Doyle et al., 1998; Lapakko et al./1998). in^pticle size are particularly important,
because crushing alters the erased acid-forming and acid-neutralizing
materials^ which in rum affeetsi^eaction (Lapakko et al., 1998). To ensure
that interpretati0ns,pf geoehemicaltest results are appropriately conservative, applicants should
carefully consider the represenfe^Sfeness of the tested samples, the similarities and differences
between the test conditions and sW«av|lcmnient, and the significance of any temporal changes in
leachate compositions noted over the'course of the tests.
Management of s61M wastes and information needs related to NEPA analyses of potential
impacts due to solid waste are discussed in Appendix F, Solid Waste Management. Applicants
proposing operations that will produce acid- or metals-generating waste rock or tailings should
provide design elements that will limit potential environmental impacts from these materials.
These.could include-steps to minimize the production of potentially reactive wastes, separation
and special handling of these materials, and/or reclamation designed to isolate these wastes from
the environment.
6.2.5 Wastewater Quality and Management
The NPDES permit process requires applicants to identify sources of wastewater and storm
water, describe wastewater and storm water management, provide water balances, and estimate
48 November 1999
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the quantities and compositions of effluents that would be discharged through permitted outfalls
throughout the year (see Table 5). Applicants must demonstrate that the wastewater
characterization is representative of discharges that will occur over the full range of operating
conditions and closure and that any effluent proposed for discharge will not resultan water
quality standards exceedences in the receiving water. In order to accom|>|Lsh thiis^applicants will
need to estimate the quantities and compositions of process solutions,. J^gigs^vater, runoff
waters, mine drainage, and treated effluent at the propose^lation^fil^ilfectiveness of
wastewater management measures (such as treatment).
Wastewater quality and quantity from tailings im|||Qdmen^nd operatif^|IS|p|ilpH
facilities may be determined from analysis of process s
pilot-scale metallurgical tests that simulate the proposed
waste rock piles and mine drainage may be predicted b
modeling. For operations proposed in areas of histori
should be collected from pit lakes, underground
from existing waste disposal facilities. Where
treated effluent should be determined from
Wastewater management, including disc
methods for disposal, and data needs fcjlNEPA
Wastewater Management. MemodsjfirfSSredict
Appendix D, Effluent Quality.
6.2.6 Pos
and Lewis, 19
e model and inp
sure in advance
d tailings waterPojiiiiried from
operations. Discharges from
ical testing and
iples of mine drainage
seeps emanating
•eatmenfiii|pposed, the quality of
sed treatment technology.
s, treatability studies,
d in Appendix E,
charge eipuent quality are described in
impoundment
made based o
Jjj
imcertaint|Jisocia
inforrn6n regarding
Quality
pit lake or underground water quality and tailings
[uired by the NEPA process. Predictions may be
and modeling. There may be a high degree of
modeling. Stochastic models, those containing
icertainty, are gaining wider acceptance as predictive tools
icre models are used, assumptions and uncertainties associated
larameters must be identified. It is also beneficial for the Applicant to
tt the model will be accepted by the regulatory agencies.
Us that disrupt ground water geochemical systems can spur mineral
Ilipitation reactions that can alter pre-mining ground water quality in ways that
lull to predict (Lewis-Russ, 1997). Mine pits that are backfilled with waste rock and
underground workings that are abandoned following ore extraction increase the opportunity for
contamination by exposing ground water to fresh rock surfaces that are not in equilibrium with
the existing geochemical system. In these situations, applicants should provide an assessment of
potential ground water quality impacts in these settings.
49
November 1999
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More detail regarding predictive water quality models is provided in Appendix D and
Appendix A.
•*••»
6.2.7 Closure and Reclamation Effects
The methods used for facility closure and reclamatiorj^afe play allarp®^nt role in
determining the potential for long-term contamination. Rifadual leach, fluids^? soluble metalj
complexes that remain in inadequately rinsed or neutralif|d heaps cart lead to 3$£pfgg •
laden acidic or cyanide-rich fluids. However, low pernfflbility cgps, covers, " "~*"
barriers installed following recontouring can lower the cont
helping to reduce infiltration and chemical flux through l^^^donent. In addition, adequately
established vegetation cover would reduce erosion and of water
from surface layers. Caps and covers also can help to limit into sulfide-bearing
waste materials. Grading and recontouring of faci^^bpes for long-
term erosion, slope failure, and sedimentation Management
Practices (BMPs) may be employed to due tflredimentation and erosion
(see Appendix H). Applicants will be reqi|red to closure and reclamation
plans for NEPA review which should adjfess whejfer permit will be required
for any post-closure discharges. Clojaip considjpttions NEPA disclosure needs are
discussed in more detail in Appenjjj^ Solidjjfaste Manjlgement and Appendix H, Erosion and
Sedimentation.
6.3 Impacts to Aqua
Freshwater
must be analy:
between studies
water quality
Ices
ssent an important component of the environment that
/A permitting processes. Considerable overlap exists
; and those characterizing surface water and ground
lany impacts to aquatic resources, including riparian areas, are
ae location of facilities. Road construction, logging, and
lills, and process facilities can reduce infiltration and increase
related to mine construe:
A
clearing of areas for buil
the amount of surface rupoff which reaches streams and other surface water bodies while
potentially reducing stream base flows. This can increase the peak flow and the total amount of
stream discharge which occurs from a given storm event. Unusually high peak flows can cause
erosion of stream banks, widening of primary flow channels, erosion of bed materials,
channelizatioli, and alteration of the slope of the channel. These impacts can affect and degrade
aquatic habitats, including riparian zones. Channelization (i.e., straightening) can increase flow
velocities in a channel reach, potentially affecting fish passage to upstream reaches during
moderate to high stream flows. Increased erosion and downstream sedimentation can impact
spawning gravels, egg survival, and frye emergence, as well as degrade benthic food sources and
riparian cover. Flooding can create high velocity flows, scour stream banks and erode or bury
50
November 1999
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gravel substrates. The destruction of cover created by large woody debris and stable banks can
impact rearing and resting habitat for fishes. In addition, removing riparian vegetation can
reduce shading. The resulting increase in sunlight can raise the temperature at the surface and
through the entire water column, and this in turn can have a profound impact on theifentire
aquatic ecosystem.
Water quality issues associated with mine exploration* operation||iii|^donment
activities typically involve the potential discharge of mine water and pr^jp|^ptipns, increased
loads of metals and other toxic pollutants, acid generation from waste^5r6ck,^^^i|||fe|;>and mine
workings. If these pollutants reach surface waters, toxic condition^ fcould affectlftD|&if!
. . * -••'>''-f"'TV^'iS'J-".^3>lm.t-;«-
aquatic species. ,, ,
Studies that are typically required for NEPA revie
include analyses offish, benthic macroinvertebrates, aijirthe p]
riparian zone, that define habitat for aquatic communities. In the
resources, especially fish, often represent the pi
evaluated. This is because resident and
and governmental agencies such as NMFJpBLM,
Commissions, and state wildlife agenci^frMany
§404 permitting
ameters, including the
;ss, aquatic
. action being
salmon), have important recreationaj|iiji/or cor
are Federally or state-listed speciej|jlatsreqi
For these reasons, applicants sho iFcomple
resources. Appendix G,
outlines to
iercial fi§
rotectioi
concern to the public
:st Service (USFS), Tribal
feularly salmonids (trout and
iry values. Numerous species also
.der the Endangered Species Act.
of the propo
e studies that c
esource
st
^determine potential impacts to aquatic
died discussion of data needs and
luatic resources.
changes that
required unde
cumulativ
on Eninmental
pr
Id provide a baseline from which to measure or predict
• of the proposed action and its alternatives. As
Sact assessment must analyze both direct, indirect and
tic resources located within the project study area (Council
The study should have a scope that extends beyond the
site. Applicants should anticipate that they could be required to
terize or evaluate:
Jf
Potential effects of water quality changes on aquatic communities and their habitat that
mayjiipl^om mine operations, including point and non-point source discharges, and
fin flow regimes. Parameters of concern may include heavy metals, pH, total
solved solids, cyanide and cyanide breakdown products (e.g., ammonia, nitrogen
compounds), and overall effluent toxicity.
Potential effects of sedimentation on aquatic communities and their habitat as a result
of construction and operational activities.
51
November 1999
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Potential effects of physical disturbance or removal of aquatic habitat and associated
riparian area on aquatic biota.
Potential effects to aquatic biota from spills that occur during the transport or storage
of fuel, process chemicals, and other hazardous ma|erials.
Potential effects of stream flow changes on aquatic; habitat and-biota that result from *
water withdrawals (both of ground and surface water), stream diversions, or ^
discharges. * -.
Potential effects of physical blockages or barrieis created by mine construction or
operation activities on fish movements. These evatpe^Httaj^hould include potential
velocity barriers that can be created in diversions, cuhre^t^l^pad crossings which can
affect fish passage through a stream reach, -- * 'm
These types of impact evaluations would normali^inclmde backjpfound studies that define
fish distribution, abundance and species composition^ am'cntf^ali^litat for spawning, frye
emergence, and juvenile rearing. Thesejftudies neeWto focus especially on game and species
listed as threatened and endangeredfi^fe) or special status. Fishery habitat studies should
include, among other factors, char^ferization^ stream gfadients, widths, depths, pool
Istream ||jj riparian vegetation, and the presence of large
: to char^^^^^^eroinvertebrate communities should define
ce and metric data, such as species richness
frequency, substrate compositio:
woody debris. Backgroum
species composition and,
and species diversity.
6.4 Impacts to Wetlands
Studies to de:
the U.S. typically have
wetlands because jurisdi
te and determine potential impacts to wetlands and other waters of
rous requirements than studies conducted to evaluate non-
Pwetlands (and other waters of the U.S.) are regulated under
Section 404 of the CWAfln" general, wetlands are aquatic areas within the landscape that include
swamps, marshes, fens, bogs, vernal pools, playas, prairie potholes, and riparian zones. These
features are considered to be "jurisdictional wetlands" if they exhibit specific conditions of
wetland hydrology *hydric soils and the presence of hydrophytic vegetation, as defined by the
accepted delineation method. The regulatory definition of wetlands and the criteria and
indicators used to identify them are discussed in detail in Appendix I, Wetlands and Other
Waters of the United States. Regulatory requirements as specified under §404 of the CWA are
discussed in section 3.0.
52
November 1999
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Wetlands may perform a variety of important physical, chemical and biological functions
including ground water recharge or discharge, flood storage, peak flood flow attenuation,
shoreline and channel bank anchoring, dissipation of erosive forces, sediment trapping, and
nutrient trapping and removal. Wetlands may also provide habitat for numerous plant, wildlife,
and fish species, including some that are listed as threatened and endangered (T&E).
Impacts to wetland areas can result from the construction|and operation of mine and
facilities including construction and use of roads; site preparation for buildings, mills and
ancillary facilities; and the construction, use and maintenance of waste and storage facilities,^
such as tailings impoundments and waste rock dumps.
indirectly. Direct impacts include the removal or des
filling, or draining. Indirect impacts are those associai
disturbed areas, increased sedimentation, and increased
pollutants. Mining operations also can impact ripari
the construction of stream diversions or by alteriri:
dewatering activities may impact wetland hydrj
ground water recharge and discharge charac
jJ
Any proposed project or activity a poteipal to
acts cap occur either^directly or
Iwetlands through dredging,
sased runoff and erosion from
Is and other toxic
|be destroyed or lost by
watershed. Mine
by altering regional
Itlands, either directly or
indirectly, will be required to fully
determine potential impacts. It isjf
place restrictions on projects
under CWA,
might
potential im
filled or drainj
required
sterize ffis resourfto establish baseline conditions, and
it tef note that and local governments may also
Id impa^wetland^fegardless of their jurisdictional status
ide a baseline from which to measure or predict changes that
osed action and its alternatives. Studies to determine
scribed in terms of acreage of absolute loss (acres
.ction. Applicants should anticipate that they may be
:erize or determine:
•etlands and their function both within and near the project area
The acreagejfrwetlands that will be directly impacted by fill or draining activities
The ejgfc^Pthat changes in hydrology, drainage patterns, or stream discharges would
le hydrology of identified wetlands and the composition of associated plant
cies
The extent to which dewatering activities or ground water withdrawals would affect
wetland hydrology and function
53
November 1999
-------
Potential increased sediment loading to identified wetlands
Fate and transport of spilled process chemicals or hazardous wastes and the potential
for spills to impact wetlands
Potential effects to aquatic and terrestrial wildlife habitat ani
impacted wetlands.
In conducting studies, applicants should specifical|||evaluate difilreri
designs, and technologies to study the avoidance and rri8imizatioi£of enviro;
wetlands. The Section 404(b)(l) guidelines indicate th
practicable alternatives exist that would have fewer adv
proposed activities cannot avoid impacts to wetlands,
steps have been taken to minimize potential adverse impacts.v'
its can only no
s to wetlands. Where
onstrate that practicable
7.0 REFERENCES
/-.
Blowes, D.W., Reardon, E.J., Jambor, Jj£, and CJ||rry, The Formation and Potential
Importance of Cemented Layers in Inacjjfi Sulfidejpine Tailings, Geochimica
Cosmochimica et Acta, voLSS, pp.
Brown, A., 1997. Groundwater Quantity
"^
Handbook, Effectgqjjjjitomg on
on Mining, ImperiafjgJiS^ge Press,
. J., ed., Mining Environmental
1 and American Environmental Controls
ion, pp. 244-248.
Council on EnvSaWtBhtal Qoa^j^j^j^Regulations for Implementing the Procedural
Provisions of the t^itionalm^Knmental Policy Act, Executive Office of the President,
40 €FR Parts
-1508.
Doyle, T.A., Murphy, S.F.? Klein, S.M., and Runnels, D.D., 1998. A Comparison of Batch and
Column Leaching Te^ts of Mining Wastes, Society for Mining, Metallurgy, and
j ,; Exploration, Inc.,- Preprint 98-103, 5 pp.
Johnson, S.W., 1997f Surface Water Quality - Sediment. In: Marcus, J.J., ed., Mining
Environmental Handbook, Effects of Mining on the Environment and American
Environmental Controls on Mining, Imperial College Press, London, pp. 149-150.
Lapakko, K., Haub, J., and Antonson, D., 1998. Effects of Dissolution Time and Particle Size on
Kinetic Test Results, Society for Mining, Metallurgy, and Exploration, Inc., Preprint 98-
114,9pp.
54
November 1999
-------
Lewis-Russ, A., 1997. Ground Water Quality. In: Marcus, J.J., ed., Mining Environmental
Handbook, Effects of Mining on the Environment and American Environmental Controls
on Mining, Imperial College Press, London, pp. 162-165.
MEND, 1995. Hydrology of Waste Rock Dumps, Natural Resources
Association of Canada Mine Environment Neutral Drainage
Project PA-1, July 1995.
a andMie Mining
Associate
Mills, C., 1998. Kinetic Testwork Procedures, Report p^ted onthe^lfflvi
http://www.enviromine.com/ard/Kinetic%20Te^^inetic^6proced
October 14, 1998.
O'Hearn, J., 1997. Surface Water Quantity. In: Marcus^
Handbook, Effects of Mining on the Environm
on Mining, Imperial College Press, London»jaie»221-:
Price, W.A., Morin, K., and Hurt, N., 1997.
Drainage and Metal Leaching
Procedures for Static and Kine
Conference on Acid Rock Dm
Schafer, W.M. and Lewis, M., 1
Impacts at Mining
98
ing Environmental
'nvironmental Controls
Prediction of Acid Rock
'art II. Recommended
rourth International
'anada, May 31 - June 6, 1997.
Shields,
Siegel
•onmental Risk of Water Quality
tallurgy, and Exploration, Inc., Preprint
, R.L., 1998. Methodology for Adequacy of Sampling
Society for Mining, Metallurgy, and Exploration,
itity. In: Marcus, J.J., ed., Mining Environmental
ing on the Environment and American Environmental Controls
Press, London, pp. 165-168.
College
m, J.H., Travers, C., and Atkins, D.A., 1998. Predicting Long-Term
''Waste-Rock Facilities in Dry Climates, Society for Mining, Metallurgy,
ation, Inc., Preprint 98-135, 7 pp.
U.S. Environmental Protection Agency, Office of Wastewater Management. 1996. NPDES
Permit Writers'Manual. EPA 833-B-96-003.
55
November 1999
-------
U.S. Environmental Protection Agency, Office of Water, 1991. Technical Support Document for
Water Quality-based Toxics Control EPA 505/2-90-001.
U.S. Environmental Protection Agency, Region 6, EID Handbook Guidance to Applicants for
New Source NPDES Permits. 1995 r
U.S. Fish and Wildlife Service and National Marine Fisheries Service, En^^red Species
Consultation Handbook. 1998 *>*5 I
,,«•?
56 November 1999
-------
-------
Mining Source Book
Appendix A — Hydrology
1.0
2.0
3.0
4.0
5.0
6.0
8.0
Table of Contents
Goals and Purpose of the Appendix A-l
Hydrological Cycle A-l
Hydrological Impacts A-2
3.1 Surface Impacts A-2
3.2 Subsurface Impacts ;.. . . " . A-4
> .^ «*
Methods to Measure and Predict Hydrological Impacts ~?f*. .1 A-6
4.1 Precipitation *•"# • % A-6
4.2 Losses from Precipitation -'/. !..":.." A-l 2
4.3 Surface Runoff r, '.^.."L.^A-IS
4.4 Stream Flow Routing .". T.*.*.t.r.'. A-18
4.5 Ground Water ..*...,* A-19
/> •> )"" -s
Development of a Site Water Balance '. '. A-20
5.1 Average Water Balance
5.2 Pond Capacity Evaluation ... A-22
6.4 Analytical and N
7.0 RejUHfltativene
Surface Water and Ground Water Modeling Jt ?
.jjjF °
6. 1 Development of a Conceual Mo
6.2 Analytical Software
6.3 Numerical Modelir^P Surface, Water
................. A-24
................. A-24
................. A-25
................. A-27
of Ground Water ................. A-27
:._ A-3i
ind Hydrological Variables A-32
Assurance Program with Data Quality Objectives A-33
A-34
List of Figures
Ground Water Systems Affected by Mining A-5
Areal Averagpgof Precipitation by (a) Arithmetic Mean, (b) Thiessen Method,
' ad Method A-9
libwpack Frequency Curve A-l 1
___ ^Hydrograph Ordinates (y values) from Rainfall Excess of Duration D
Proportional to Ordinates of D-minute Unit Hydrograph A-16
A-5. Runoff Hydrograph from a Complex Storm A-17
A-6. Summary of Methodologies Available in HEC-1 A-28
A-i
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Mining Source Book
Appendix A — Hydrology
1.0 GOALS AND PURPOSE OF THE APPENDIX
Developing a mine plan of operation, designing operational procedures, and designing
hydrological control structures and other best management practices (BMPs) to prevent
environmental impacts all require accurate knowledge of the variables associated with
hydrological conditions at a mine. Of particular importance is proper characterization of baseline
hydrological and hydrogeological conditions so that the extent of impacts to hydrologic and other
related resources can be minimized or avoided. Mining operations must accurately consider two
main hydrologic components when planning operations: (1) process system waters, often
referred to as the process circuit, and (2) natural system water| or the nai^jOTbuit. The
primary goal of this appendix is to outline the methods and^B§^icarpK^ffi$s, commonly used
to characterize the natural system waters at a mine site. IiiUfied are deiiilSMin^of the rationale
* '' ' ' ~ > * * ^
, - -
and methods for characterizing surface water hydrology Jifround
water-ground water interactions. The characterization, M|41ing?,4nd
waters are discussed in Appendix E, Waste-water Mana
Natural system waters are those associated with
ground water and meteoric water from precipitation, s:
mining operations, important data for establishing^
measurement of precipitation, runoff, and losses
al., 1981). Impact evaluations and.the prope
pregnant ponds and barren ponds, tailings
characterization of hydrological parame|
surfac
•drological cycle, such as
|pn, and runoff. For
e hydrologic
Evaporated
clouds. Ultima
e hydrolig^pp&iditions include the
ipitation (Barfield et
strictures, diversions, culverts,
spend on accurate
2.0 HYDROLOGICAL CYj
distribu
convenient
condensation,
flow.
le" gene^^^pied to describe the continual circulation and
ents of me environment. The hydrological cycle is a
elation between six fundamental processes:
ion, infiltration, surface runoff, and ground water
: be viewed as beginning with the evaporation of water from
fthen collects in the air, and under proper conditions, condenses
?, tne clouds may release this water as precipitation which
juently collects and is dispersed in one of three ways. The largest part is
rily retainedjphe soil near where it falls. This portion is returned to the atmosphere by
jn andj«|>iration by plants (Linsley et al., 1975). Another portion of this water
soil and recharges ground water reservoirs. The final portion of the
preespllipw'runs off the surface and collects in stream channels and lakes. Under the influence
of gravity, the ocean receives portions of both the stream flow and ground water flow and the
cycle begins again.
Obtaining adequate data for predicting and determining hydrological processes at
proposed mining operations presents significant challenges. These processes are very complex
A-l
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Mining Source Book
Appendix A — Hydrology
and have high variability, making measurement and characterization for predictive purposes
difficult. Understanding the hazards and benefits of the hydrological cycle will assist in proper
mine operations and contribute to environmental protection. In addition, hydrologic processes
are related to other important resources such as water quality, aquatic life, vegetation, wetlands,
and terrestrial wildlife.
3.0 HYDROLOGICAL IMPACTS
Characterizing hydrology at a mine site is necessary tg identify
affected by mining activities; determine impacts to the re
resources; and develop appropriate monitoring programs
hydrological conditions should be characterized in ord
changes can be measured or predicted and to identify
potentially impacted by mining activities. The intent o
nature and extent of ecological impacts from mining-relai
If past or present mining activities have been underway,
sources should be examined. It is important that the
conditions and hydrological effects of a mine exteni
to place the project in the context of its waters
Hydrological studies can be used to?pfedict
activities. Potential mining-related impacts to hydiplogy d;
sica
mitigatiq
provide j
conditions!
that would be
and biological
ackgrouryL'
d*
be
eterization is to aitonine the
in the hydrological system.
logical effects from these
drological baseline
boundaries in order
i proposed mining
Darated into surface and
subsurface systems. Surface and subsurface hydrological sjjjstems are likely to interact with one
another and they can impact other related resources.
3.1 Surface Impacts «
Many surface water hydrological impacts are related to mine construction and the
location of facilMesT Road consttuc^pyiogging, and clearing of areas for buildings, mills, and
process facilitiesJcan%e^|^infiltralipHi and increase the amount of surface runoff to streams and
other surface-water bodieslsThis can increase the peak flow and the total stream discharge
associated with a given ^onnre^sht. Unusually high peak flows can erode stream banks, widen
primary flow channels, erode bed materials, deepen and straighten stream channels, and alter
channel grade (slope). Iniurri, these changes in stream morphology can degrade aquatic habitats.
Channelization (i.e. straightening) can increase flow velocities in a stream reach, potentially
affecting fish passage^to upstream reaches during moderate to high stream flows. Increased
erosion upstream and the resulting sedimentation downstream can impact spawning gravels, egg
survival and emergence of fry, as well as degrade benthic food sources. A detailed discussion of
erosion and sedimentation as related to mining is provided in Appendix H, Erosion and
Sedimentation.
The location of mining facilities frequently requires the construction of stream diversions
and/or storm water ditches that control and divert runoff from upland watersheds. Typically,
these structures are used to prevent unpolluted water from contacting potentially degrading
A-2
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Mining Source Book
Appendix A — Hydrology
materials, such as waste rock, or flooding over disturbed areas and degrading water quality.
Drainage control structures also are used to prevent operational difficulties which could occur at
the site. Although these structures may mitigate and control potential impacts from flooding or
erosion from disturbed areas, they often alter or change natural drainage patterns in a watershed,
which, in turn, can impact vegetation resources, wetlands, and wildlife habitat.
The discharge of process waters potentially can affect water quality and lead to impacts to
resources such as aquatic life. Parameters associated with wastewater treatment andMischarge
are discussed in Appendix E, Wastewater Management; those associated with the management of
solid wastes, such as waste rock and tailings, are discussed in AppendixFf£?/M Waste
Management.
Stream flow effects caused by mining operations relate directly to potential impacts in1
water quality. It is common for many water quality constituents to correlate inveaiely with*
stream flow (i.e., chemical concentration increases with decreasing stream flow). This is usually
true for the concentrations of total and dissolved metals and most chemical constituents that
occur in higher concentrations in subsurface formations titoti ifiu
constituents, however, correlate positively with streanAow (ine
increasing stream flow). This condition is typical
surface soils, land applied pollutants, such as
that are transported as suspended particles. I-ipease;
highest for those areas with the largest amgnflint of s
Receiving Waters, water quality data mujfbe coll
effects of stream flow at a site.
Withdrawals from stre;
flow can potentially affect
the yei
different
adult passai
(minimum) fl
-------
Mining Source Book
Appendix A — Hydrology
water from) mine workings, adits, or open pits is required when the mine elevation extends
below the potentiometric surface in confined aquifers or below the water table in an unconfined
aquifer. Pumping ground water lowers the water table in the immediate area of a well, creating a
"cone of depression" which extends radially outward from the well. The radius of drawdown
depends on the level that the water table is lowered by the well, the pumping rate, the hydraulic
conductivity of the aquifer, and the homogeneity of the aquifer. Water supply wells located close
to one another may have cones of depression that overlap, creating a cumulative effect on the
drawdown of the water table. When this occurs, the drawdown at a given point bej|ines the sum
of the drawdowns caused by all of the wells (Linsleyetal., 1975). Ad
large diameter well; consequently the water table in an aquifer can be
large radial distance. Drawdown can affect the direction of ground
gradients and lines of flow toward the mine or well field.
Drawdown of an aquifer potentially can lead to
reduced surface water flows in streams that are gaining
1). These effects can impact wetlands associated with
streams. A reduction in stream flows can also affect aqi
me acts as a
for a relatively
shifting
wai
A-
y need t
ic surfj
regional lowering of the water table can impact neighboring water
Water yields from local wells can be reduced or
for the decreased elevation of the water table <
characterization of ground water and hydrog
conditions. However, sufficient characteri^ffion of]
S£J$-
that could occur on local and regional scales.
In areas where ground
conditions, mining impacts to
The factors associated with
:•'"%•:, *
quality are-discussed in
sprang and see
fffa
tesj»ect to ground
iparian zones associated with
id fish populations. A
id irrigation wells.
deeper to account
equate
ally for fracture-flow
quired to predict impacts
e to varying influent and effluent
.t in impacts to surface water quality.
water and resulting impacts to water
A-4
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Mining Source Book
Appendix A - Hydrology
Polenllometrlc Surface (Elevation
Of Water Table) In
Upper Aquifer
Infiltration
Potenllometrlc Surface
(The Level To Which
Water Would Rise) In
Lower Aquifer
Potenllometrlc Surface In Lower
Aquifer Due To Underground
Mining
Upper Aquifer
(Unconlined)
Aqultard
Lower Aquifer
(Confined)
-Inleraqulfer Flow From Aquifer
With Higher Head To Aquifer
With Lower Head
Figure A-l. Ground water flow systems affected by mining (Siegel, 1997).
A-5
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Mining Source Book
Appendix A - Hydrology
4.0 METHODS TO MEASURE AND PREDICT HYDROLOGICAL PROCESSES
The design of water collection, storage and treatment facilities at mine sites depends on
adequately characterizing the hydrologic system in the vicinity of the site. Precipitation, losses
from precipitation (i.e., interception, infiltration, and evapotranspiration) runoff, and stream flow
are perhaps the most important parameters to measure during baseline studies. Estimates of the
hydrological inputs to a mine and the design of detention structures, retention ponds, culverts,
pregnant and barren solution storage ponds, and diversion channels depend on probabilistic
determinations of rainfall and runoff events that are developed from historical data. Van Zyl et
al. (1988) indicate that short-duration, high-intensity events, large snow-melt events, or extended
wet periods are the most important rainfall-runoff events to^epnsider during heap-leach facility
design. Unfortunately, rainfall-runoff parameters and probabilistic determinations of future
' ^^ ~
rainfall-runoff events are among the most difficult to accurately determine. •>
Mines often are located in remote areas or in watersheds licking historical precipitation
and runoff data sufficient to accurately develop retum-periodand,flood-frequency relationships.
For this reason, it is important for the hydrologist to
possible given the cost, scope, and data available.
runoff and developing probabilistic distribution
compared below. For more detailed informaticj
who provide an excellent compendium of h;
operations.
4.1 Precipitation
Precipjtation depth-
numerous, widespread cli
published iTaflases by th
These historical dataalso are's
these are the only^dalaiiiitially
developing probafri
inputs for water bal
rigorous estimates
precipitation and
iefly outlined and
arfieldetal.(198l),
lyses for mining
. for the United States is available for
:al stati^p||jjpi|ed by the U.S. Weather Service and
:eanographic and Atmospheric Administration (NOAA).
lectronically on magnetic tape and compact disk. Often,
-mining operations and they serve as the basis for
^use in designing hydrological structures and evaluating
5. Actual measurements of precipitation and runoff within
the specific watershed of^R|effi^re preferred and should be used whenever possible to develop
probabilistic storm frequehef relationships and design hydrological structures. Since remote
mine areas usually lack the long-term historical data necessary to develop accurate probabilistic
relationships, most mine projects need to establish a network of climatological stations and
stream-flow monitoring stations to collect records for their watershed(s).
Mean areal precipitation within a watershed or in sub-basins often is used to develop
rainfall-runoffprobability relationships and for input to other hydrological analyses. The
accuracy of these values, or of the historical relationships developed from them, depends on the
density of precipitation gages throughout a basin. Studies conducted to analyze precipitation
gage density and the errors associated with using these data for estimating runoff and stream flow
conclude that a higher density of gages is required where topography is more complex and where
convective thunderstorms can be expected to provide significant hydrological input to the system
A-6
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Mining Source Book
Appendix A - Hydrology
(Eagleson, 1967; Johanson, 1971; Bastin et al., 1984). Linsley et al. (1975) provided the
following general guidelines for precipitation station density based on climatic conditions and
topography:
• One station per 600 to 900 km2 (230 to 350 mi2) in flat regions of temperate, Mediterranean,
and tropical zones with relatively high rainfall;
• One station per 100 to 250 km2 (40 to 100 mi2) for mountainous regions of teinperate,
Mediterranean, and tropical zones; and
• One station per 25 km2 (10 mi2) for small intricate moujiljaqus
precipitation.
It is important to note that the accuracy of deveL
for rainfall-runoff events for a specific basin will greatl'
gages increases. This is particularly true in basins where
occur in localized areas yet provide significant flow ai
in the watershed. Three common methods are used to
network of precipitation gages: (1) the arithmetic
(3) the isohyetal method. Figure A-2 depicts
mean is a simple average of the stations am
accurate. The other methods apply wei
(Barfield et al., 1981). The Thiessen mjfiod dett '; •>
f|jj|lygon method, and
s. The arithmetic
ipply but the least
.ces between rain gages
areas for each gage based on
.e weighting factor for the isohyetal
between adjacent isohyetes or lines
most accurate of the three methods;
weighting factors for precipitation gages
ent network has not changed. A detailed
methodologies is presented by Linsley et al. (1975) and
ion caflswgvaluated using kriging techniques. Kriging is actually a
i to analyze spatial data. It was originally derived for
ion. In general, kriging uses linear regression techniques to
ith the estimate of a new point. The estimate is made from a
the error associ
variance model djiveioped from the entire network of data points. In effect, kriging
ically evaluates from an entire set of spatial data, such as a network of precipitation
:o make of interspatial data. The output can then be used to develop an
mapjji^llFto that described above. The difference between the two techniques is that
;etal method uses linear interpolation between two precipitation gages to
Sis between two points. Kriging uses statistical methods to estimate values between
two points, taking into account data from other nearby gages. Karnieli and Gurion (1990)
described the use of kriging to map areal precipitation and applied it to historical precipitation
data for the State of Arizona. Kriging is the most intensive technique to evaluate areal
precipitation and specific software is required. For most mining scenarios, however, it would
provide better estimates of precipitation inputs, especially in areas with complex topography and
est
A-7
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Mining Source Book
Appendix A - Hydrology
in areas where precipitation is spatially more variable. Use of this technique would help to
minimize errors associated with rainfall-runoff measurements and to develop more accurate
probabilistic relationships over time.
As previously indicated, historical rainfall data are used to develop probabilistic
relationships for rainfall and/or runoff events. These relationships describe the frequency or
probability of occurrence (i.e., return periods) of rainfall or runoff events. Some common
methods for developing these relationships are the Log-Pearson Type III distribution,' the
Extreme Value Type I Distribution^ and the Gumbel Distribution. The methods for developing
these relationships are described in various hydrologic manuals and will not be described here
(see U.S. Bureau of Reclamation, 1977; Linsley et al., 1975; Barfield etaL, 1981).
Van Zyl et al. (1988) described an application ofJfhe Weibull (1939) foimulalhatjitiM?es
available historical snow pack data to develop probabili^c^relationships for snow'mel^^fey
indicated that local snow data often are not available for^fpsotic^lar basin of interestanfflhat
historical snow course data obtained by the Natural Resowpg^^grvation Service (formerly, the
Soil Conservation Service [SCS]) must be used. Figure^.
probability/return period relationship developed for a siibw pa
are similar to those developed for precipitation andfl^^f events.'"
that the best methods to estimate runoff from based of
rather than more complicated analytical moc
solar radiant flux, and other variables.
hour factor and the average probability
available for specific regions of int
combining snow-water equivalen^pasureme^ with othJF watershed physical parameters to
provide better estimates of runof^fem sno^i^gck. Thgjpsign engineer should note, however,
that the prediction of nmoffj^priiaiow-pa^^^p^is complicated by other hydrological
jexampleof a
s of relationships
al. (1975) indicated
e air temperature,
feed, relative humidity,
a degree-day or degree-
. These data typically are
described a GIS method for
factors such as ground w;
. . -.-. ..-..»^T. "
precipitation toa^vioccurs
moisture deficiency, and the amount of
insleyetal, 1975).
A-8
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Mining Source Book
Appendix A - Hydrology
Arithmetic mean:
1.46 + 1.92 + 2.69 + 4.50 + 2.98 + 500
Observed
precip.
(in.)
626
2.84 in.
correspond
within basin boundary
Isohyetal method:
Area*
enclosed
(sq. mi.)
Precipitation
volume
(col.3xcol.4)
Average = 1634 + 626 = 2.61
* Within basin boundary
Figure A-2. Areal averaging of precipitation by (a) Arithmetic Mean, (b) Thiessen Method, and (c)
Isohyetal Method (Linsley et al., 1975).
A-9
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Mining Source Book
Appendix A - Hydrology
Probabilistic relationships, such as those of Figure A-3 or those published by NOAA,
provide maximum precipitation depths or intensities for certain durations and frequencies of
occurrence. These data can provide peak-flow or runoff estimates for use in designing
hydrologic facilities and structures. In addition to peak flow data, modern design criteria, often
require more detailed information regarding the runoff hydrograph. Developing runoff
hydrographs typically requires temporal information for storm events (i.e., time versus
precipitation intensity relationships) (Barfield et al., 1981).
A plot of the distribution of rainfall intensity versus time is called,?an hectograph.
Methods to develop design hyetographs (also termed design s|prms) or average
time distributions that are based on actual storm events al., 1988 and
Koutsoyiannis, 1994). The time distribution of rainfall inlfelfity great!
affects the quantity and time distribution of runoff. Desipi storms.
theoretical storm runoff for the design of structures, dra||f|ge, orjpntainment ]
methods commonly used to create design hyetographs into three CE
described below (Chow et al., 1988; Koutsoyiannis, 19$
agle, bimodal, or
ined by the Natural
SCS(1972). This
II distributions. The
ication in Alaska and
RCS known as the Type I-A.
The first category uses pre-selected time distri
uniform distributions. The most commonly
Resource Conservation Service (NRCS [formej
method uses two theoretical time distributio:
Type I distribution is recommended for u:
Hawaii; however, an additional distribu;
The Type I-A distribution producesj&ljievere silk nmofijEes than the Type I distribution and
is more suited to simulate storm asspjjied with J|f coastal regions in the northwest
United States. For this reason, I-A^Jtributi^« recommended for use in Washington •
and Oregon and should Alaska. The climate of southeast
Alaska and is more closely related to that of
British Cc>l^ii§|^ashih^||^^^regon.^Tle Type II distribution is applicable to the
remainder of-il§^^^d problem with using these methods is that two or three
average distriBi|^^pejtiot types of storms or for all areas where they are
recommended^! ?use. ^Another mafSipffoblem is that the runoff hydrographs produced from
these methods do not ttave-aaoy,real measure of the probability or frequency of occurrence.
Thirdly, these distributioii&ljasasaH design events on a 24-hour distribution. Despite these
problems, average time distributions, particularly the NRCS distributions, are commonly used for
design studies because of fiieir simplicity.
A-10
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Mining Source Book
Appendix A - Hydrology
PROBABILITY OF EXCEEDANCE (%)
30.0
90
80 70 60 50 40 30 20
2 5 10
URN PERIOD (YEARS)
Figure A-3. Typical snowpack frequency curve (Barfield et al., 1981).
A-ll
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Mining Source Book
Appendix A - Hydrology
The second category of methods is based on regionalized average distributions and the
probabilistic occurrence for that time-intensity distribution. An example of this type of
distribution is described by Huff (1967). These methods are based on better
probabilistic/statistical approaches than those described above. However, Koutsoyiannis (1994)
indicated that the exact determination of the probability of the resulting runoff hydrograph is still
ambiguous for use in design.
The third category of design storms is based on the intensity-duration-frequency (IDF)
curves of the Probable Maximum Precipitation (PMP) for the region of interest These methods
do not rely on average or probabilistic time-intensity distributions withm rainfall events. Instead,
hyetographs are designed to apply maximum depths (i.e., w4i||.case ^cenaadbs)©f rainfall based^
only on the frequency of occurrence for that depth and foj|p)articular;
Unfortunately, like the methods discussed in the first the
occurrence of the resulting runoff hydrographs are ambfEabus andjindefined.
Regardless of the specific method used to calculai
the IDF design storms are conservative, which makes tb
purposes. This is because they use PMP to create peakfkows
aspects of rainfall, infiltration, and runoff. Althou^^^ge meth
designs, they can bet cost effective because envin
because of their relative ease of use.
|fhe hydrographs produced .by
d choice.for design
idering the physical
t in conservative
lly protective and
Koutsoyiannis (1994) describedjpourth rnJftod, si
design storms for the purposes of hyjjrliogical jJpRgn.
techniques (i.e., a Markovian strucfi^fe)4o cogdpbnly use
^r??'"'-^ '3jjj$
-------
Mining Source Book
Appendix A - Hydrology
distribution of the soil, porosity, antecedent moisture content, surface roughness, macroporosity,
freeze-thaw cycles, and fluid properties all affect infiltration and each responds uniquely to storm
intensity and duration. Field methods that are used to measure infiltration include double ring
infiltrometers and rainfall simulators.
Several empirical methods are available to estimate infiltration. The most common of
these are models by Green and Ampt (1911), Morton (1940), and Holtan (1961), and variations of
these models. The original Green and Ampt model is commonly used by many computer
hydrological models when adequate data are available to describe soil hydrological variables and
antecedent moisture conditions. Barfield et al. (1981) indicated that for naning-applications, the
application of these methods is limited by the difficulty in measuring ihe physical parameters
necessary for input. Accurate application also is confounded "by the nonun|mto of soils, both*
spatially and with depth, and the high variability of all conditions across
important, therefore, that a hydrologist apply good professional judgment
assumptions when using these methods to estimate loss rates from precipitation.
McLaughlin Engineers (1969) suggested that specific field-tests were preferable and highly
useful when making these estimates or applying professioo&ICjudgfrient.
4.3 Surface Runoff
In the conceptual hydrodynamic model, excejpf
established channels and channel flow ijjrouted tolttasin
hydrological structure will be de
the runoff hydrograph from data ap-precp,
or through a structure. In some
structures to;
used to roi
are si
protect or cont
rethroi
•f.
Jectior
routed as overland flow to
a location of interest where a
be used to develop and analyze
to route the flow down a channel
's, onlyJiEanalysiflif overland flow is required to design
ition at a mine site. Methods commonly
iins, or other hydrologic control structures
The mi
the volume o£
The meth
curve
ibed is the most common technique for estimating
ation^^wunoff) after losses to infiltration and surface storage.
soil-types within a watershed and applying an appropriate runoff
to of excess precipitation for that soil and vegetation cover
is method was for agricultural uses, and Van Zyl et al. (1988) suggested that
lly is not accurateMough for most design purposes at mine sites, primarily because the
?pment and classification of runoff curve numbers by the SCS are imprecise. Curve
rs are approxjjpie values that do not adequately distinguish the hydrologic conditions that
and forest sites and across different land uses for these sites.
f~,,'
appropriate technique for developing and analyzing runoff at mine sites utilizes
the unit hydrograph approach. A unit hydrograph is a hydrograph of runoff resulting from a unit
of rainfall excess that is distributed uniformly over a watershed or sub-basin in a specified
duration of time (Barfield et al., 1981). Unit hydrographs are used to represent the runoff
characteristics for particular basins. They are identified by the duration of precipitation excess
that was used to generate them; for example, a 1-hour or a 20-minute unit hydrograph. The
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Mining Source Book
Appendix A - Hydrology
duration of excess precipitation, calculated from actual precipitation events or from design
storms, is applied to a unit hydrograph to produce a runoff hydrograph representing a storm of
that duration. For example, 2 hours of precipitation excess could be applied to a 2-hour unit
hydrograph to produce an actual runoff hydrograph. This runoff volume can be used as input to
route flows down a channel and through an outlet or for direct input to the design of a structure.
Detailed procedures for developing unit or dimensionless hydrographs are presented in a variety
of texts (Chow, 1964; Linsley et al., 1975; U.S. Bureau of Reclamation, 1977). The volume of
runoff (i.e. precipitation excess) derived from an actual or design hyetograph is multiplied by the
ordinates of the 1-inch unit hydrograph to produce a runoff hydrograph fora particular storm.
Figure A-4 graphically demonstrates how a 1-inch unit hydrograph for dilation D is used to
produce a runoff hydrograph from 0.75 inches of precipitation excess "of duration D. Figure A-5^
demonstrates how a 1-inch unit hydrograph of duration D is used to develop a Q.7 inch runoff
hydrograph by summing three components of excess precipitation from a complex fibrm with
each component of duration D (Barfield et al., 1981).
are produced for each component of the storm using tl
hydrographs produced are lagged according to the durat
as shown on the x-axis of Figure A-5. The individual
summed to produce a 0.7 inch runoff hydrograph.
Common methods to develop and use u
Clark (1945), and SCS (1972). Unit hydro;
from actual stream flow runoff records fo:
perhaps the most commonly applied mi
hydrographs. The SCS (1972) publi
Type II curves for creating designjpfpn's and
precipitation excess. Most mine/^fte desi
determining precipitation excessihan thos
caseindividual runoff kydrographs
ifmt hydrograph. The^*
proponents of the hyetograph
s produced are then
bySnyder(1938),
can also be developed
CS (1972) method is
iphs and produce runoff
the SCS Type I, Type I-A or
e number method to determine
of more rigorous techniques for
SCS (1972).
Ano&eie technique to• determine runorflrom basins or sub-basins is the Kinematic Wave
Method. TMs meBjodapplief the kmematic wave interpretation of the equations for motion
(Linsley et al., ii^iio:|jrovide estra^esfef runoff from basins. A summary of the theory and
the general appMc^ioiifEttiis method far determining runoff is provided by the U.S. Army Corps
of Engineers (1987)"mMJ&sm^the operation of the HEC-1 computer software package. If
applied correctly, the me^&^f^provide more accurate estimates of runoff than many of the
unit hydrograph procedurelsiilscribed above, depending on the data available for the site. The
method, however, requires detailed site knowledge and the use of several assumptions and good
professional judgment jn its application.
As previously indicated, only peak runoff rates for a given frequency of occurrence are
used to design many smaller hydrologic facilities, such as conveyance features, road culverts, or
diversion ditches around a mine operation. The hydrograph methods listed above can be used to
obtain peak runoff rates, but other methods are often employed to provide quick, simple
estimates of these values.
A common method to estimate peak runoff rates is the Rational Method. This method
uses a formula to estimate peak runoff from a basin or watershed:
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Mining Source Book
Appendix A - Hydrology
Q = C i A
(A-l)
where Q is the peak runoff rate, C is a dimensionless coefficient, i is the rainfall intensity, and A
is the drainage area of the basin. A comprehensive description of the method is given by the
Water Pollution Control Federation (1969). The coefficient C is termed the runoff coefficient
and is designed to represent factors such as interception, infiltration, surface detention, and
antecedent soil moisture conditions. Use of a single coefficient to represent all of these dynamic
and interrelated processes produces a result that can only be used as an approximation.
Importantly, the method makes several inappropriate assumptions that dognot apply to large
basins or watersheds, including: (1) rainfall occurs uniformly ..over a dg^^||i?ea, (2) the peak
rate of runoff can be determined by averaging rainfall intens^over equal to the
time of concentration (tc), where tc is the time required fordprecipitationsei^^pf^fe the most JSP
** A ^•y'iT' A. ,gfe; ^ *" ^ Jj^^iv^^'^^ff^^i^^^^ v&f^1^
remote point of the watershed to contribute to runoff at
of runoff is the same as the frequency of the rainfall ejplion is
made for storage considerations or flow routing through^^^^fted) (Barfield etiil|iRi). A
detailed discussion of the potential problems and by using this method has
been outlined by McPherson (1969).
Other methods commonly used to estimate^
and SCS TR-55 methods (SCS, 1975). Like th|
commonly used because of their simplicity.
use in urban situations and for the designjaplmall dj
method is that only runoff curve numbejplare used«fS> calci
watershed or sub-basin is representeJplfPa unifo|pt land use
generally will not be true for mosl^sfeershedsJt' sub-bask
, R-20 (SCS, 1972)
5hniques are
primarily derived for
major assumption of the
:ss precipitation. In effect, the
type, and cover, which
A-15
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Mining Source Book
Appendix A - Hydrology
TIME
- RAINFALL EXCESS
v- = .75 inches
Figure A-4. Runoff Hydrograph Ordinates (y values) from rainfall Excess of Duration D
Proportional to Ordinates of D-minute Unit Hydrograph (after Barfield et al.,1981).
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Mining Source Book
Appendix A - Hydrology
D-MINUTEUNIT
^ RUNOFFJsfifDROGRAPH
15 TIMES UHV- =0.15 inches
Figure A-5. Runoff hydrograph from a complex storm is obtained by summing the ordinates (y-
values) of individual hydrographs from D-minute blocks of rainfall excess (Barfield et al., 1981).
The hydrograph from each component of the complex storm of D duration is lagged by duration D,
as shown on the x axis.
A-17
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Mining Source Book Appendix A - Hydrology
The Rational Method and the SCS methods generally lack the level of accuracy required
to design most structures and compute a water balance at mine sites. This is because they
employ a number of assumptions that are not well suited to large watersheds with variable
conditions. However, these methods are commonly used because they are simple to apply and
both Barfield et al. (1981) and Van Zyl et al. (1988) suggest that they are suitable for the design
of small road culverts or non-critical catchments at mines. Van Zyl et al. (1988) suggested that
the Rational Method can be used to design catchments of less than 5 to 10 acres.
It is important that the design engineer and the hydrologist exercise good;professional
judgment when choosing a method for determining runoff as discussed,aikwe. Techniques
should be sufficiently robust to match the particular design e^feia. It rs particularly important
that critical structures not be designed using runoff input ejSiflates made by?«s^^olating an
approximation, such as that produced by the Rational MeMbd, to areas or sitoaifea^ghere itjj
not appropriate. Robust methods that employ a site specific unit hydrograph i
Wave Method will produce more accurate hydrologicalHesigas?%ut will be:
consuming to use. Nevertheless, many of the more robus| methods have data requirements that
often cannot be fulfilled because the available data are statistically inadequate. This may force a
hydrologist to use their professional judgment to estimate input parameters or to use data that are
not statistically adequate for their designs. Design and planning documenfevshould describe the
uncertainties associated with any assumptions or-cafcubttions, including fliBlse used to provide
conservatism to the design. %,* •'" '"
/X > . ^
ff ' y
4.4 Stream Flow Routing , '
/* / °»
1 \ ' '
f ' , /
Designing hydrological stipctures or,c$oiducting,water balance studies often requires an
evaluation of the hydrologicjnputs'to the ujsper reaches or sub-basins of a watershed. As these
flows are obeyed to the airfte^tte, either in natural or constructed channels, their flow
iified>fey .te^ellime, chaimer storage, and the effects of influent and effluent
reaches. l^^era^Whods are avaS&le, to evaluate or study how flood flows are routed through a
reservoir, a seriescpjjonds, or anert^^^tructure. These techniques also can be used to design
constructed charllls^ ,\
f* vs
Methods commonly used to route flows in channels are the Muskingum Method, a variant
called the Muskingum-Cunge Method, the Modified Puls Method, and the Kinematic Wave
Method. A detailed review of the general theory of flood routing and how each method solves or
approximates the governing equation for continuity is beyond the scope of this appendix. The
reader is referred to texts by Barfield et al.(1981) and Linsley et al.(1975) for more detailed
discussions of how these methods are applied to mining. A summary of the theory and general
application of these methods is also provided by the U.S. Army Corps of Engineers (1987) in
their description of the HEC-1 computer software package.
The Kinematic Wave Method is a more robust technique that solves the continuity
equation and, if applied correctly with appropriate data, can provide more accurate analyses of
flood routing. As previously mentioned, this method requires the use of several assumptions and
good professional judgment in its application.
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Mining Source Book
Appendix A - Hydrology
4.5 Ground Water
Because most mine sites are located in regions with complex hydrogeologic conditions, a
thorough understanding of the site hydrogeology is required to adequately characterize and
evaluate potential impacts. Aquifer pump tests and drawdown tests of wells need to be
conducted under steady-state or transient conditions to determine aquifer characteristics. It is
important that these tests be performed at the pumping rates that would be used by aimining
operation and for durations adequate to determine regional impacts fromdrawdowr^lnd potential
changes in flow direction. These tests require prior installation of an apjlopriairnetwork of
observation wells. Transmissivities, storage coefficients an,d|^rtical aad horizontal hydraulic
conductivities can be calculated from properly designed pjiip%sts. These measurements are /"'
necessary to determine the volume and rate of ground w||lr discharge expected during mining '
operations and to evaluate environmental impacts. Test||hould be performedfor'aD aquiferJ at a
mine site to ensure adequate characterization of the relafr "" ..-•«-
units. Characterization studies should define the relation
water, including identifying springs and seeps. Signifies
system also need to be identified.
between hydrosttatigraphic
veen ground water and surface
•sinks to the surface water
Hydrogeological characterizations shoul
region. Descriptions of rock types, intensity
orientation of faults, fractures, and joints
Although difficult to evaluate, the hydrqjppcal e
especially important to distinguish. mov
dissolution zones, collectively term^yieconi
Secondary permeability can presf|pl!gmiic
can result in a greater amoun||pfjpound
faults that u£pose di:
to
Igologic,
Ijhering
ions of the site and the
the abundance and
ysis and monitoring.
oints, and faults are
.ore easjlfTnrough faults, fractures and
ermeabjpy, than through rock matrices.
'blemsjlor mining facility designs because it
'than originally predicted. For example,
geological properties can cause abrupt
Srporated into facility designs.
round water flows is described in Section 6.0. The
use of comput
prediction^
solutior
A
equatiJifs used to characf
accuracy of hydrogeological analyses and impact
on of complex mathematical relations through use of numerical
alter modeling has not changed the fundamental analytical
Infers and determine ground water quantities. Traditional
y discussed below. The application of ground water modeling
discussed in Section 6.2.
Mw
commqn||p€thod to analyze ground water in relation to a mine relies on a simple
ppih which the mine pit is approximated as a well. This method uses the
cdil|ippip**facob-Lowman (1952) equation to calculate flow rates. Although not as
sophisticated as a numerical (modeling) solution, this method gives a good approximation of the
rate of water inflow to a proposed mine. It generally yields a conservative overestimate of the
pumping rates required to dewater a mine (Hanna et al., 1994). A second method uses the
technique of interfering wells, where each drift face of the proposed mine is considered to be a
A-19
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Mining Source Book
Appendix A - Hydrology
well. The cumulative production of the simulated wells is used to estimate the total influx into
the mine and the extent of drawdown.
5.0 DEVELOPING A SITE WATER BALANCE
An accurate understanding of the site water balance is necessary to successfully manage
storm runoff, stream flows, and point and non-point source pollutant discharges frcu^a mine site.
The water balance for typical mining operations will address process system and natural system
waters (Van Zyl et al., 1988). Process system waters, which include make-up water, chemical
reagent water, operational start-up water, water stored in wasteipiles, water Tetained in tailings,
and mine waters (miscellaneous inflows), have reasonablyjlfestant and predictable flows. JP
Natural system waters include rainfall, snowmelt, evapojpon, and seeps and sprtt^,which Mve
variable and less predictable values (see Section 4.0). Ajlbverall .site water
superimposes these two systems to account for all watei
A mine site water balance must recognize that
during mine operations. For example, in a heap leach
ponds, the heap leach, and the ore itself. Water is lostJrom the
evaporation; facilities such as spray systems ma>
evaporative losses. Natural precipitation such;
process ponds increases the total amount o|pater in
sred in various facilities
^ stored in the process
; through
significant
-ap
g
additives that are used in the processing yore. Du
permanent shutdowns, water collected, |i the facilities, incl|
must be stored in the process pondsfl|njheap l||pn *
or chemical solutions to neutrdizJli; environmental ir
the ore (Van Zyl et al., 1988>, Bpa tailingsj
water, runoff^and other ty^p^^aters su<
tailings.^ laossek jnclude'^Sp^^toed in
dam), pond evafteafiion, ancNl
leach pads or
iy liquid chemical
fown, or other temporary or
the ore itself, will drain and
, the ore must be rinsed with water
of chemical reagents remaining in
ig type operation, inflows include tailings
vater that are often co-managed with
I, seepage (to ground water beneath the tailings
operat.
waters.
A key asieSiifi^^water DlHiiat a site is the long-term variability of precipitation
4@--»i'-'• •&•.•*& '?'&&, •:"'H'feSi':-1 ^g&te*'/ ^ * f
amount, intensity;--aa^MiasiliqBa. Precipitation events can significantly change the estimated
surface water and grouhd^^a^olumes used in the water balance assessment. In turn, this can
change the determination^0fl^feuier a system will have a net gain or loss of water. For a mine
*•* • , -" 'v.%"-:,. •, -•' * ^
witka gaining system, such as those in wetter climates, some type of a water disposal system
may be required to achieve a balance. Typical disposal systems include evaporation ponds,
surface outfalls, and ground water recharge systems. A mining operation with an overall losing
system^s in dry climates, usually requires continual input make-up water. A site with an overall
losing system may-still have a net gaining system for short times, such as during periods of high
precipitation or snowmelt. Water disposal systems may need to be designed to manage the water
balance during these periods.
Process ponds should be sized to contain all water that would be in circulation during
facility operations and during periods of temporary shutdown or rinsing and closure. A water
balance is required to determine the sizes of these ponds (Van Zyl et al., 1988). In addition to
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Mining Source Book
Appendix A - Hydrology
•holding the required volumes of process solutions, ponds must be able to accommodate
additional water that flows into the system during extreme precipitation events.
Brown (1997) describes methods to determine a site water balance using both
deterministic and probabilistic approaches. Deterministic water balances, similar to that
described in Section 5.1, use set input values (e.g., average annual precipitation) to compute
inflow and outflow. To provide insight into the range of conditions that could be expected to
occur, deterministic water balances should be computed for average, wet, and dry conditions. In
contrast, the input values used in probabilistic approaches are sampled from probability
distributions (e.g., annual precipitation probability). Computer spreadsheets are used to
iteratively calculate inflow and outflow probabilities. According to Brown, (1997), probabilistic
approaches result in better facility designs because they can mdicate which parameters have thes
most effect on model results and may reveal potential desjgn weaknesses.
5.1 Average Water Balance
=•
< „ r •
The concept of an average water balance can be stated with the folio wing mathematical
formula: v V ^ ,
* '
f^ •*! % jtf
A-.. A &
(A-2)
where S is the total storage requirementgjETd I and^are inflows and outflows,
respectively (Broughton and Tape, Usina^cyanid^H|neach operation as an example,
the components of the average wat^afance §jfl>utlmedj|i 'follows (Van Zyl et al., 1988):
Water Balance Period»(Tl
componen|diiill be evali
rinse-cy^
permanent
removed, the51
Dandi
may
.s is which the average water balance
enough to include a complete leach
this equal the actual leach-rinse time. For a
segments of ore that are either being leached, rinsed, or
a number of these cycles.
Free
averagej|llcipitation ol
pad.
is evaluated by multiplying the long-term
' by the total area contained within the berms around the leach
Evaporation froJIhe Ore and Pad (E) - Evaporation for the period T can be evaluated
sither a factor rjjpiplied by the Class A pan evaporation and the irrigated area at a
• time or using spray-loss graphs. Only the period during which actual leaching
Sould be used when determining the pan evaporation.
Water (R) - Laboratory tests are usually required to determine the amount of
rinsing water and reagents that must be applied to adequately clean the spent ore before disposal.
Rinse-water volume may be as high as seven or eight pore volume displacements.
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Mining Source Book
Appendix A - Hydrology
Soil Storage CS) - Soil moisture conditions vary in the heap during the ore placement,
leaching, rinsing, and draindown periods. Each change in ore moisture results in water being
taken up and stored in the pile or being drained from the pile into the ponds. Some of the water
stored in the heap leach pile will not drain. Various moisture contents in a heap leach pile must
be taken into consideration, including natural moisture content, agglomerated moisture content,
field capacity or specific retention, and moisture content of the heap leach pile during leaching.
Net Evaporation Loss from Presnant and Barren Ponds (EP) - This is calculated as the
area of the ponds multiplied by the gross lake evaporation, minus the average precipitation over
i Ponds
y stems,
period T. In some cases, the evaporation rate may be modified by the
Normal Operating Water Stored in Pregnant and
contain sufficient water to facilitate operation of the p
fluctuations in operating the system.
Water Stored in the Process Facility (SPR) -
vessels contained in the process facility. It is generally
thoroughness.
Reagent Addition (RA) - This equals the
throughout the operating period T.
After the above par
system, terrDtedjthe balan
stry.
rods need tajf
equal to the capacity of
is included here for
the reagents used
*fr -**- ^fiSiS, r^ff
Bleed Water (BL) - This is the antoiint of b|ffen tiHRnrfbed to prevent the buildup of
/- ^f §•*• /"y *• *•
concentrations of certain constituentsl^values thfst are sufljtefently high to interfere with mineral
if3f... ju& *,„> •* °
extraction.
rerall average water balance of the
fated as follows:
\- E + R - EP - BL + RA -S
(A-3)
^ •"&$.'-^•^•T^ ^:-^:,"^f^K~fff<.-
Negativejmpes'dfBF indiclppiait the system will require additional water, on average,
equal to the apiioiHtt'of BF» ^Positive vlhies indicate that water storage in the system will build up
and exce$s%ater must be disposed.
* rf ,,v* ot&- >££ ~t
5.2 *"w Evaluating Pond Capacity
_\, t
.x-f5-1 /^'
The water storage facilities at any site must be sized to contain the amount of water that
would be in the system during a low probability, wet hydrological event (i.e. the worst-case
scenario). Pond sizes should take into consideration the conditions that are likely to prevail
during winter and total system shutdown, as appropriate. The conservativeness of the hydrologic
event used in pond design depends on regulatory requirements, economic considerations such as
the cost of additional pond capacity, the value of processed ore, and especially the environmental
consequences caused by exceeding storage capacity.
A-22
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Mining Source Book
Appendix A - Hydrology
During operations, process pond capacity should be evaluated monthly to measure
fluctuations caused by changing precipitation and evaporation conditions. Performing monthly
and quarterly evaluations permits close inspection of the operational aspects that may affect
water storage requirements. Moreover, the monthly evaluation gives an indication of the critical
or maximum storage capacity needed during any month.
The storage capacity of process ponds at a site typically is based on the worst-case
climatic condition (i.e., a low-probability, high-flow event). In drier climates where,.pn average,
the system operates with a large negative water balance, the critical duration of the design storm
event usually is relatively short, varying from 1 to 60 days. During tliese events, the water
system will show a net precipitation gain, thereby allowing |||=system to exceed storage capacity.
In wetter climates, the critical duration is longer and may Jap'Over an entire season or over
several wet years. Once again, it is prudent to consider alange of durationsxand choose the
worst-case scenario (Van Zyl-et al., 1988).
The critical duration design criterion is extreme!
considered, even though such evaluations may be beyon<
requirements. If the critical duration evaluation is not
conservative or dangerously overly optimistic pond sj
examples from Van Zyl et al. (1988):
Overly Conservative Design - Ass'
probable maximum precipitation event
it and should always be
; of the regulatory
be unnecessarily
gtwo scenarios are
rthe
ent prescribes a 6-hour
ater balance calculations
the return period of the design
asthetriti
indicate that the critical duration is 15,days. Analysis sho
event exceeds 1,000 years, which i^^onsideredtdverly conjprvative. Designing for this event
means that there would be less tfiaasifO.l percent chancgjil overtopping a pond during any 1
sj^f^ * f&&~
year.
event as
moderately w
actual return
pond will 9;
probabi^^of overtop
deemslmnacceptable.
it the reglMKfry requirement prescribes a 24-hour, 100-year
ermore, assume that the operation is located in a
duration is actually 60 days. Analysis shows that the
'ess than 25 years. This means the chances that the
year. During a 20-year leach operation life, the
:eed 80 percent. By most standards, this design would be
In cases where cgflcal duration analysis produces overly conservative or overly liberal
3, applicants shJiSd provide to regulatory agencies calculations disclosing the probability
foMfilferent critical durations as a part of their impact analysis. Further iterative
' sS-U/pfy''
fmay be warranted.
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Mining Source Book
Appendix A - Hydrology
6.0 SURFACE WATER AND GROUND WATER MODELING
Mathematical models can be solved analytically or numerically. Either type of solution
may involve the use of a computer. Analytical solutions are usually simple in concept and
assume a homogeneous, porous media. Numerical solutions are usually more appropriate for
complex, heterogeneous conditions. In general, models become more complex as fewer
simplifying assumptions are used to describe a system or approximate a set of governing
equations. ^ •>
Anderson and Woessner (1992) suggest answering the followin^ig|iisstkms to determine
Silk ' '" K'11 :l><%. &'"•&'
the type and level of modeling effort needed: ™"
• Is the model to be constructed for prediction or systejpnterpretatiipii, olfei||||l||
modeling exercise?
• What should be learned from the model? Whatque
• Is a modeling effort the best way to obtain the i
• Can an analytical model, rather than a more
used to obtain a solution?
Answers to these questions will
use to conduct a water balance study
they will help to determine wheth
transient, or, especially for gro
conducted in one-, two-, or
.ri^,''^;-*^.^- £t
Applicants.will
flow and may nofereplicate _T7__.
fracture flow may^^^ke applief
interconnection
and Woessnef^WZg
equivalent porous mediuip@
therm
esign
ution
ter sol
imensio
agh
logi
uld be
ns, whe
>u want the model to answer?
numerical model, be
w
to determine the methods to
letures at a mine site. In addition,
ytical or numerical, steady state or
a modeling effort should be
'and Woessner, 1992).
it many
id water flow models assume porous media
1 mines where rocks are intensely fractured. Modeling
ect additional data on the number, width, and
Woessner, 1992). As described in detail in Anderson
systems can be modeled by invoking conceptual models of
ete fractures, or dual porosity. Each of these conceptual models
' - :, '-. '/l- Vv ^ '"'
uses assumptions that oversimplify flow through the fractured system. Consequently, applicants
should exercise caution wneninterpreting the results of models developed in this manner.
~'v. ^.=ivy "
6.1 Developing a Conceptual Site Model
A conceptual site model can be used to address the questions and evaluate the parameters
discussed in Section 6.0. This model is a depiction, descriptive, pictorial, graphical, or
otherwise, of the surface and subsurface hydrological systems, how they interact, and how they
are related. The conceptual model should be developed concurrently with site characterization
studies to determine important geologic formations, hydrostratigraphic units, and surface water
interactions. A carefully constructed conceptual model will reveal important interrelationships
A-24
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Mining Source Book
Appendix A - Hydrology
that need to be evaluated, studied, or modeled. In addition, it will provide a basis for developing
plans to monitor site conditions, analyze impacts, and construct numerical ground and surface
water models. The conceptual model is usually simplified to consider only significant surface,
subsurface, and interactive components because a complete reconstruction of actual field
conditions is not feasible (Anderson and Woesner, 1992). It should be sufficiently complex to
accurately depict system behavior and meet study objectives, but simple enough to allow timely
and meaningful development of modeling or other analytical solutions.
The conceptual model provides a tool for identifying the questions to analyze using a
mathematical model. Comparing the boundaries, dimensions, and input parameters of a
particular mathematical model against the conceptual mode|||||pnits a user to evaluate the
ability of the mathematical model to meet assessment neejlilffiis type of comparison may , :
indicate that specific components of the surface or subsujfice hydrologic system caim.pt be yif*
simulated easily using a mathematical model. In this ca||i the conceptual moae^canbe used to
identify additional site characterization needs or model llpfa^^lare needed to accarately model
specific components.
Conceptual model development begins by de:
conditions of that area. Boundary, conditions may inj
conditions across the boundary. The main stepsj
define hydrostratigraphic units (these may
depending on the degree of complexity re
water budget that identifies sinks and soj
systems to be studied or modeled.
6.2 Analytical Software
erest and the boundary
or hydraulic
ng a cofl^^pinodel are to: (1)
>nd to geologic units,
yes); (2) develop a general
define the type of flow
irface
g
watershec
of these prog
flow routing, a
a particular;
watershejlfrrecipitatio
IF^
ilable ISiliayze surface water hydrology, perform
jcal structures are considered "analytical" software. Many
;sed in Section 4.0 for analyzing precipitation, runoff,
programs allow a user to apply different algorithms to
pmparWuie solutions. The output from one analysis, such as a
It analysis, can be easily utilized by other routines to analyze
^structure. One problem that can be associated with the use of
ilied using a computer or by hand calculation) is that they are easy
iesign
Kd route flows t
: models (whethj|a_
apply. As discusjji in Section 4.0, it is important that the mining hydrologist understand
aptions and ajfioximations used by different methods and in what situations different
approbate.
,„ ^^lstGeological Survey has published a compendium on the use of surface water
modeislBurton, 1993). A complete review of this publication is beyond the scope of mis report;
however, the publication outlines recent research and application of surface water modeling
techniques and the use of interactive spatial data systems, such as the use of satellite imagery and
Geographical Information Systems.
A-25
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Mining Source Book
Appendix A - Hydrology
only used
analyses for use"
196?4f
Most analytical software used for hydrological analyses and structure design is available
through the private sector. Some surface water hydrological, water quality, and groundwater
software programs and models are available through the United States Geological Survey
(USGS). Many of these programs and their manuals can be accessed and downloaded to a
computer from the USGS via the internet (as of February 1999: water.usgs.gov/soffware). Brief
descriptions of some of the more commonly used programs are provided below with particular
emphasis on those that typically are used in mine settings.
HEC-1 Flood Hydrograph Package
HEC-1 (U.S. Army Corps of Engineers, 1987) is p
software for conducting watershed analyses and performij
in structure design and water balance studies. The pro;
the U.S. Army Corps of Engineers Hydrologic Enginee:
been modified and improved throughout the years and
been released.
HEC-1 generates hydrographs from rainfall andjif snctt
routes the flow through stream reaches, reservoirs, andjietentiori^
stream and reservoir networks, and has dam faili
simulate level-pool routing for reservoirs am
techniques incorporated into HEC-1, man;
TR-20 Project Formulation Hydrolo,
','">, ^
TR-20 (Soil ConservationJiSfirvice, perforgfphydrograph generation, additions, or
diversions, reach routing, or muft|ple TR-20 uses the SCS methods to
generate runoff hydrographs Igsed on specified for any storm duration.
Hydrographs ace computed^^fe^andard §Wnype I, I A, or II rainfall distributions, or other
design hy<
HMR-52 Probable Maximum
iphical) versioriiylsjSlsntly
or diverts them, then
.odels multiple
e program can
outlines the
ection 4.0.
HMR-52 (Hansen etaLf 1982) computes basin-average precipitation for Probable
Maximum Storms and fmSs the spatially averaged Probable Maximum Precipitation (PMP) for a
watershed. The PMP can be used directly with HEC-1 to compute runoff hydrographs for the
Probable Maximum Flood (PMF) as the basis for dam spillway and failure analyses.
• -^ &
HECWRC Flood Flow Frequency
HECWRC performs a statistical analysis of historical stream flow data and plots the
resulting flow-frequency curve. The program places both the observed and computed probability
curves on the same plot. HECWRC uses the Log-Pearson Type III distribution as discussed in
Section 4.0 to compute the return frequency curve.
HEC-2 Water Surface Profiles
A-26
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Mining Source Book
Appendix A - Hydrology
HEC-2 (U.S. Army Corps of Engineers, 1991) software employs methods commonly
used in open channel hydraulics and in the design and analysis of hydrologic structures. HEC-2
computes water surface profiles for steady or gradually varied flow in natural or man-made
channels. It handles subcritical and supercritical flows and can analyze the performance of
culverts, weirs, and floodplain structures. HEC-2 is used for evaluating flood hazard zones and
designing man-made channels or channel improvements.
6.3 Numerical Modeling of Surface Water \*
~% ,*.*
A variety of software is available that combines analfiteal solutions with numerical
modeling techniques to create watershed models. In genej|J- Sese models employ finite-
difference or finite-element techniques to route hydrograj|is and pollutants throragh surface-water
systems. These models are particularly useful for eval
non-point sources of pollution through a watershed. S
operations to evaluate and model potential operational e
the NPDES permit process. Two of the more commonly
,
J
w ^
ig the fafe and transport of point and
»|f|& type could be used by mining
•eleases in conjunction with
are described below.
Hydrologic Simulation Program FORTRAN (HSPF)
|s that simiiates the hydrologic and
frfaces, in the soil profile,
HSPF (Bicknell et al., 1997) is a set
associated water quality processes on perv^^and ij
and in streams and well-mixed impoundjEiits. Th^5pera|[^p|^ffiiection between the land
surface and the instream simulation is a^Kmplishfd'tinough a network block of
elements. Time series of runoff, sejjjnent, and^pollutant leadings generated on the land surface
are passed to the receiving strean^wsubseq^ent transport and transformation simulation. Water
quality and quantity can be along dM^rent^ments or at outflow points within a
watershed..
Water En
unsaturai
infiltration
precipitation is
wave meth
;nt transport c
and
Model (WEPP)
ane, r^K^aesigned to use soil physical properties and
,
-------
Mining Source Book
Appendix A - Hydrology
containment structures may have failed and knowledge of contaminant transport to natural
ground water systems is required.
Overview of HEC-1 Computer Program
U.S. Army Corps of Engineers
Precipitation Analysis
User Enters Time Intensity Distril
Any Distribution
Any Duration
Capable of HandlinjjpultipleSt
Infiltration Analysis
SCS Curve Numt
Hpltan Loss Rate
Green and Ampt
Initial and Unifoi
Exponential]
Routii
.Musfcirigum
|skinguhi-Cunge
"ified Puls
Forking R&D
Kinematic Wave
• • ''•'•• ''•. >• '• •
ther Features
Reservoir Routing
Dam Break Approximations
Watershed Calibration
Flood Damage Analysis
Pumping Plants
Diversions
Figure A-6. Summary of methodologies available in HEC-1.
A-28
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Mining Source Book
Appendix A - Hydrolc
Most ground water modeling software is available through government agencies or the
private sector. A thorough description of ground water modeling and the assumptions associated
with its proper application is beyond the scope of this report. Instead, the reader is referred to the
text by Anderson and Woessner (1992) for a detailed discussion of modeling techniques and
applications and to a report produced by EPA in cooperation with the Department of Energy
(DOE) and the Nuclear Regulatory Commission (NRC) that provides technical guidance
regarding the development of modeling objectives, the development of site conceptual models,
and the choice of models for use in particular problems (EPA, 1994). A brief description of
ground water modeling and its application to mining is provided below. JL description of some
of the more common ground water modeling programs is also providec||i^i1^ticular emphasis
on those that are commonly used in mine settings. ^
Van der Heijde (1990a) defined a ground water:
the processes active in a ground water system. Models
solutions being the least complex and numerical met
element methods, being the most complex. A comparis
numerical methods is detailed by Pinder and Gray (1971
simulate transient flow in ground water aquifers (Frees
Ground water models can be used to simj
of coupled processes describe the hydrology
of near surface and deep aquifer systems. jjjfund
mathematical description of fluid flow absolute
,*Jy$f!r
unsaturated zones and take into consjjsltion th<
The predictive capabiliti
The accuracy and efficiency
simplificatijiliyised in tfo
charact
and con
provide a vial
dewatering ope.
environme:
groun
Simula
the acci
lei as the nSllhemalfcal description*bf
•*• f, f
ite-difference or Unite-
d-difference and finite-element
les are widely used to
0-
IF
s in which a variety
istry, and biochemistry
so incorporate the
or both the saturated and
of hydrogeological systems.
•f
depend on the quality of input data.
the applicability of the assumptions and
process information, the accuracy of site
made by the modeler. Where precise aquifer
reasonably well established, ground water models may
adequately predict inflow to a mine pit, evaluate
it fate and transport studies, locate areas of potential
'urces, and assess mining operational variables.
be classified into two broad categories. The first includes flow
mojlp that describe theS^dlfulic behavior of single or multiple fluids or fluid phases in porous
oiaHptured media. Thjipecond category includes contaminant/chemical fate-and-transport
; that analyze tipraovement, transformation, and degradation of chemicals in the
ice. A discussion of model classifications is presented by van der Heijde et al.
IpP5
ie modeling process consists of defining the problem, creating and calibrating the
model, and conducting an analysis for a particular mining scenario or problem. Analysis of the
water management problem in question is used to formulate modeling objectives and create
simulation scenarios. Key elements of the problem definition step are conceptualizing the
ground water system and analyzing and interpreting the existing data. Conceptualizing the
A-29
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Mining Source Book
Appendix A - Hydrology
ground water system includes: (1) identifying the hydraulic, thermal, chemical, and
hydrogeologic characteristics of the system; (2) determining active factors such as pumping rates,
artificial recharge, injection, or other anthropogenic factors, and passive factors, such as natural
recharge, evaporation, and seep discharge; and (3) analyzing the level of uncertainty in the
system (Kisiel and Duckstein, 1976).
The model calibration phase begins with the design of a computational grid that provides
the basis for discretization of spatial parameters (van der Heijde, 1990a). Model calibration is
accomplished by running iterative simulations, starting with field parameters and system stresses,
followed by improving initial estimates based on the differences noted by comparing computed
with observed values. As input parameters are continually refined, the model becomes more
precise representation of the physical system.
After the model is calibrated to field conditions,!
estimates. In this phase, different engineering designs,
can be evaluated. Van der Heijde (1990a) suggests that
in conjunction with predictive modeling to assess the reli|
A '''"'fKr .$
Develop ogejcational "
Establish (^ fifiestones
•-*'''
to makepedfativ« 5''"'<'
•ations, or failure stKaarios
analyses should be conducted
simulation results.
_____ f v'f*°A
During any modeling application, a lack of daj^pan impelL^
simulation. Insufficient data can result from datal
temporal sampling of time-dependent variable
(1990b) presents specific guidance on settiilfup i
water modeling studies. The major elemjjats whicbphoi
for modeling include:
jency of the
!on, inadequate
! Van der Heijde
.) programs for ground
rated into a QA program
Formulate QA objectives and^puired
accuracy, completeness, jpdJjpmparab:
:erms of validity, uncertainty,
for performing adequate modeling studies; and
||nd external auditing and review procedures.
The, QA-rjlan sfeppjldress colecting data, formulating the model, conducting
sensitivity analyses, and^fe-^abh'shing guidelines for model calibration criteria. Ground water
modeling for use in hydrltogiojdesign or water balance studies should incorporate a QA plan that
addresses specific modeling objectives and the above parameters, depending on the risk
associated with the specific design or study.
|p JCommonly used programs for developing ground water models are briefly described
below. These models were chosen to demonstrate the capabilities of some of the software
available in the public domain.
ATI 2 3D
AT123D (Yeh, undated) uses analytical solutions for transient one-, two-, or three-
dimensional transport in a homogeneous, anisotropic aquifer with uniform, stationary regional
A-30
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Mining Source Book
Appendix A - Hydrology
flow. The program allows for retardation and first-order decay when evaluating contaminant
transport problems and permits simulation of a variety of source configurations, including point
source, line source, and areal source inputs. It further allows the use of several boundary
conditions to define flow parameters; longitudinal, horizontal and vertical transverse dispersion
values can be input independently. The model calculates concentration distributions in space and
time.
MODFLOW
MODFLOW (McDonald and Harbaugh, 1988; Harbaugh and McDonald, 1996) is
perhaps the most commonly used software for creating grouj0i|water models and conducting
predictive studies. MODFLOW is a numerical model thattises1! fmite^difference solution to *
solve the governing equations for ground water flow. It
areal or vertical models as well as quasi-three-dimensio
Because of its numerical approach, it can be used to nn
under anisotropic and layered aquifer conditions. Laye:
unconfined, or convertible between the two conditions.
"pinch out". The model allows for analysis of ext<
drains, evapotranspiration, and interaction with surfi
software has been accepted for use by many re
FEMWATER/FEMWASTE
FEMWATER (Yeh, 1987) is
solve the governing equations for
areal or vertical models as well a:
unsaturated media. Becausejsf
dfo&^
steady-state|JJ||v under
media.
model (FEMW
partially sa
be used
full three-dimensioDal models!7
"^P&BS?" *1*H :L~ V*
lent flow or steady-smte flow
\ > &> y-
.ulated as confined,
n also handle layers that
ss wells, areal recharge,
streams. This
a finite-element solution to
!bw. It crf^be used to create two-dimensional
iensionajpnodels in both saturated and
: can be used to model transient flow or
r conditions. FEMWASTE is a
: of dissolved constituents through porous
jde: convection, hydrodynamic dispersion, chemical
^transport model is compatible with the water flow
fective Darcy velocities in porous media that are
JAM/DATA REPRE
ATIVENESS
i
\. It is critically jpportant to adequately understand the unique hydrology of a particular
Mine sjy^may be situated in areas where precipitation rates vary significantly over a
,, die to orographic effects) or in remote areas for which meteorological records
^i mountainous terrains, snowmelt and rain-on-snow events may produce large flow
volumff that are difficult to quantify. These uncertainties make it difficult to characterize the
entire hydrologic system.
Because the quality of field data available for mine sites may vary substantially, it is
critical to know the advantages and limitations of the different methods that may be used to
A-31
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Mining Source Book
Appendix A - Hydrology
characterize site hydrology. As discussed in Section 4.3, the standard methods for predicting
runoff must be used cautiously in mine site planning. The unique geographical and
meteorological settings often encountered at mine sites mandate careful consideration of the
assumptions used and require model results to be correlated with actual field data and conditions.
The nature of mining inevitably impacts the hydrology of a site, in terms of both water
quantity and quality. Often, baseline hydrologic conditions are not well characterized because
historical data either are unavailable or inadequate, or because the data have not beea1vadequately
evaluated. Preventing potential environmental impacts requires that a mine site'|swater system,
both the natural and facility systems, be adequately evaluated. Evaluati^s|oJ|aHti conclusions
concerning environmental impacts to site hydrology and wa|^t|gualit
precise and accurate as those of other economically imporjiptiaspects q||
example, the studies, conclusions, and disclosure of potejfpal hydrologieal
impacts should be at least as accurate as those concemirj||he certaiity and exi
economic ore deposit.
: at least as
For
The selection of appropriate statistical analysis
predictions are linked to data representativeness. Thosi
best fit the population characteristics should be idem
procedures for use in baseline characterization
initial efforts to design a basic characterizati
statistically analyze existing hydrological
influence the selection of data analysis
watershed presumed to be hydrologieiif sum
7.1 Statistical Concepts and Hydrolo
fj*. * A'* ^.K"--. -r.°*.-^y * *
the accuracy of their
ures whose assumptions
iate data analysis
ride, 1986). In
'stem, necessary to
iracteristics that will
sting data, data from a
to provide initial estimates.
skewness, andcoefficient
distributions, differences in
and confidence ia the estimated v;
£?'
hydrological data include the mean, variance,
Statistical methods use hypotheses and tests to determine
reen objects, the significance of those differences,
For many hydroli^eap|ai|iables and environmental contaminants, the basic statistical
assumptions of independeol|pftially distributed data are not realistic because environmental
datatcommonly are corrected and non-normally distributed, with variance that may change over
time (Gilbert, 1987). Fsor hydrological and water quality data in particular, there are three
commonly assumed parameters which may not apply to hydrological studies (Ward and Loftis,
1986): (1) independence of observations, including the absence of seasonaliry or serial
dependence; (2)-homogeneity of variance over the period of record; and (3) form of the
probability distribution, (e.g., normal or non-normal). For these reasons, the statistical
characterization of hydrological data for calculating mine water balances should include time
series plots and testing for normality.
The many statistical techniques that can be used to characterize hydrological processes
are presented in the references cited and will not be discussed herein. However, the following
A-32
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Mining Source Book
Appendix A - Hydrology
paragraphs present examples of two commonly used statistical methods for predicting
components of a mine site water balance. Statistical techniques used for flood frequency analysis
are presented in Section 4.0.
Linear regression is used to define the relationship between two variables whereas
multiple regression is used to explain how one variable varies with changes in several variables.
Analysis of Variance (ANOVA) can be used to determine the most or least significant variable.
For example, single factor linear regression can determine the relationship of runoff volume to
rainfall volume while multiple regression can determine the effect of multiple watershed
characteristics (e.g., basin size or shape, stream length, stream density) om;HinoWpeak
< - "sX^r; ;*
discharges. Regression also can be used to analyze trends,
water quality differences, measure variance, and extend h:
to an ungaged basin or stream.
Factor analysis can be used to evaluate comple?
variables and determine their separate and interactive ef
hydrology would be to determine significant factors of i
runoff, such as determining effects of basin size, shap
geomorphological factors.
7.2 Development of a Quality Assur
about flow and
gaged basin
The difference between the
is a measure of data quality. Allh;
including inconsistency and
data. Inconsistency is the di
homogene^^^ects a c
lows
Predict
conelusiof
and with tole
The
between a large number of
ample of factor analysis in
iredicting watershed
getation type, or other
?Quality Objectives
fro
erro
ic measured or calculated value
. to random errors, systematic errors
idom errors always are present in
Falues and true values while non-
Jen place between sampling events.
?5f hydrologic variables requires that the
free of significant inconsistency and non-homogeneity,
£h, 1972).
"uncertaint
id how often to]
jnty tnafcan be tolerated depends on the intended use of the data.
eptable is a critical part of the monitoring design (i.e., what,
, therefore, must be incorporated into the sampling program.
The levi
wnerl
StaJiRcal design criteriaSioWd be defined within any monitoring program. These criteria set
I on the confidenceMi the data by specifying the acceptable uncertainty in the estimated
les.
sT) identifies four categories of data validation procedures that should be
j^zmffs*"'
(I) Routine checks made during the processing of data. Examples include looking for errors
in identification codes (those indicating time, location of sampler, method of sampling,
etc.), in computer processing procedures, or in data transmission.
A-33
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Mining Source Book
Appendix A - Hydrology
(2) Tests for the internal consistency of a data set. These include plotting data for visual
examination by an experienced analyst and testing for outliers.
(3)
(4)
Comparing the current data set with historical data to check for consistency over time.
Examples are visually comparing data sets against gross upper limits obtained from
historical data sets, or testing for historical consistency using the control chart test.
Tests to check for consistency with parallel data sets, i.e., data sets thought: J%be from the
same population (i.e., from the same time period or similar stream,). Three'tests for
consistency are the sign test, the Wilcoxon signed-ranks test, anjllleyiplcoxon rank sum
test. These tests are discussed by Gilbert (1987).
Data reliability can be assessed using ANOVA toll
and regional (between sites) variability. If replicate s
analysis of variance can determine whether there is a
sources of variation. Basic assumptions for ANOVA tei
distributions and equal variances. ANOVA methods can
aid data interpretation.
8.0 CITED REFERENCES
Anderson, M.A. and Woessner, W.W.,
Flow andAdvective TransporAjjjjcademi
Barfield, B.J., Warner, R.C., and
Disturbed Lands, Oklahoma Tec
ditraw^pKWeen
random samples, normal
additional sampling and
Modeling: Simulation of
York, NY, 381pp.
r^f
fed Hydrology and Sedimentology for
Iwater, OK, 603 pp.
Bastin, O, LoreBt, B., Dmqae*C^aEd Gevefsff»!ri984. Optimal Estimation of the Average
Area! Rainfall and Oj^BiiplSelection of Rainfall Gauge Location, Water Resources
Researc^voL2fi, no. 4, p?
Xjj^**^ *> -^ v^ $&$&> f
Bicknell, BJ^lmhofl; J.C., Kittle, IL., Jr., Donigian, A.S., Jr., and Johanson, R.C., 1997.
jtfjji^J?rogram - Fortran, User's Manual for Version 11, U.S.
^Environmental PrIlSiplii'Agency, National Exposure Research Laboratory, Athens, GA,
^Report EPA/600/R^9^D80, 755 pp.
Broughton, S. and Tape, R., 1988. Managing Heap Leach Solution Storage Requirements. In:
C.O. Brawner, ed., Proceedings from the Second International Conference on Gold
Mining, Society of Mining Engineers, Littleton, CO, pp. 367-379.
Brown, M.L., 1997. Water Balance Evaluations. In: Marcus, J.J., ed., Mining Environmental
Handbook, Effects of Mining on the Environment and American Environmental Controls,
Imperial College Press, London, pp. 476-496.
A-34
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Mining Source Book
Appendix A - Hydrology
Burton, J.S., ed.5 1993. Proceedings of the Federal Inter agency Workshop on Hydrologic
Modeling Demands for the 90's, U.S. Geological Survey Water-Resources Investigations
Report 93-4018.
Chow, V.T., 1964. Handbook of Applied Hydrology, McGraw-Hill, New York, NY.
Chow, V.T., Maidment, D.R., and Mays, L.W., 1988. Applied Hydrology, McGraw-Hill, New
York, NY.
A
,j
Clark, C.O., 1945. Storage and the Unit Hydrograph, Transactions ofth&Amencan Society of
^. .-, T-, . , , , .. ,. + *,.., -* ..Gia*«li,«L- ^ J
Civil Engineers, vol. 110, pp. 1419-1446.
Eagleson, P.S., 1967. Optimum Density for Rainfall Nelf|brks, Water^eso^eWj^earch, vol
3, no. 4, pp. 1021-1033.
Foster, G.R. and Lane, L.J., 1987. User Requirements: Erosion PredicWon Project
(WEPP), NSERL Report No.l, USDA-ARS, Research Laboratory,
West Lafayette, IN, 43 pp.
Freeze, A., and Cherry, J., 1979. Groundwater,
Gilbert, R.0,1987. Statistical Methods foA
Reinhold Co., New York, NY.
Green, W.H., and Ampt, G.A., 19
Through Soils, J, Agro
Hanna, T.,
1, Inc.,%l|||ifbod Cliffs, NJ.
ronitoring, VanNostrand
: I. Flow of Air and Water
'an Analytical Solution for Preliminary
" Mining Engineering, vol. 46, pp. 149-152.
Hansen, E.
Estimate,
Hy
,F., 1982. Application of Probable Maximum
105lh Meridian, National Weather Service,
). 52. U.S. Department of Commerce, National Oceanic
ation, Washington, D.C.
HarJ^gh, A.W. and McJJjbiMd, M.G., 1996. User's Documentation for MODFLOW-96, An
Update to the Urn Geological Survey Modular Finite-Difference Ground-Water Flow
Model, U.S. Gflogical Survey Open-File Report 96-485, 56 pp.
r! A Concept for Infiltration Estimates in Watershed Engineering, U.S.
liiment of Agriculture Publication, ARS 41-51.
Horton, R.E., 1940. Approach Toward a Physical Interpretation of Infiltration Capacity, Soil
Science Society of America Proceedings, vol. 5, pp. 339-417.
A-35
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Mining Source Book Appendix A - Hydrology
Huff, F. A., 1967. Time Distribution of Rainfall in Heavy Storms, Water Resources Research,
vol. 3, no. 4, pp. 1007-1019.
Jacob, C. and Lohman, S., 1952. Nonsteady Flow to a Well of Constant Drawdown in an
Extensive Aquifer, Transactions of the American Geophysical Union, vol. 33, no. 4, pp.
559-569.
Johanson, R.C., 1971. Precipitation Network Requirements for Stream/low Estimatjpn, Stanford
University Department of Civil Engineering Technical Report 14,7, Palo Att6, CA.
JriSs-i- .;=>. ,.'"f''-:- '• '
Karnieli, A., and Gurion, B., 1990. Application of Kriging
Mapping in Arizona, GeoJournal, vol. 22, no. 4, ppj9-398.
Kisiel, C., and Duckstein, L., 1976. Ground-Water Mo
Approach to Water Management,
Koutsoyiannis, D., 1994. A Stochastic Disaggregation Storm and Flood
Synthesis, J. Hydrology, vol. 156, pp. 193-225, '*" ~ "
Linsley, R.K., Kohler, M.A., and Paulhus, 2"* edition,
McGraw-Hill Series in Water Ej|meermg, McGraw-Hill,
Inc., New York, NY, 482 pp.
McDonald, M.G. and Harbaugh, A.W||p88. Ajjodular 1fK>imensional Finite-Difference
Ground-Water Flow Model&j}. Geol^cal Siirvjf Techniques of Water Resources
Investigations, Book 6, C|
ill
McManamoiViA., Day, Snow Water Equivalent Using
I.S. Federal Interagency Workshop on
for the 90's, U.S. Geological Survey Water Resources
3:18-25.
McPherson, the Rational Method of Storm Drain Design, Technical
Memorandum Urban Water Resources Research Program, American
Jfc Society of Civil New York, NY.
^ «f
Pinder, G. and Gray, W.j 1977. Finite Element Simulation in Surface and Subsurface Hydrology,
Academic Press/New York, NY.
Siegel, J., 1997. Ground Water Quantity. In: Marcus, J.J., ed., Mining Environmental
Handbook, Effects of Mining on the Environment and American Controls on Mining,
Imperial College Press, London, pp. 164-168.
Snyder, F.F., 1938. Synthetic Unit Hydrographs, Transactions of the American Geophysical
Union, vol. 19, no. 1, pp. 447-454.
A-36
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Mining Source Book
Appendix A - Hydrology
Soil Conservation Service, 1972. National Engineering Handbook, Section 4, U.S. Department
of Agriculture, Washington, DC.
Soil Conservation Service, 1973. Computer Program for Project Formulation Hydrology,
Technical Release No. 20, Soil Conservation Service, U.S. Department of Agriculture,
Washington, D.C.
Soil Conservation Service, 1975. Urban Hydrology for Small Watersheds, Technical Release
No. 55, U.S. Department of Agriculture, Washington, DC.
U.S. Army Corps of Engineers, 1987. HEC-1 Flood Hydro^japh Pcrd^e*:|feestad Methods,
Inc., Waterbury, CT. Jjfl'^ >^'"'
U.S. Army Corps of Engineers, 1991. HEC-2 Water Sujjnce Profiles^
Waterbury, CT.
U.S. Bureau of Reclamation, 1977. Design ofSmc
United States Government Printing Office, Wasjpfng
U.S. Environmental Protection Agency, 1994.
Selection at Sites Contaminated with,
Environmental Protection Agency,^
U.S. Department of Energy,
Regulatory Commission, OffiiM^f Nucle
DC.
Model
Dances, gerim Final, U.S.
Emergency Response;
lion; and Nuclear
and Safeguards, Washington,
. 127.19/2:D18/977,
nd Status Kef
Research Labora
Van der Heijde, P., 1990a
Int
'dwater Protection and Remediation,
flGWMS) Groundwater Modeling
Van der Heij
Internal
^ance in the Application of Groundwater Models,
"ling Center, Report GWMI 90-02, Golden, CO.
.d Williams, S., 1988. Groundwater Modeling: An Overview
Sivironmental Protection Agency, R.S. Kerr Environmental
Ceport EPA/600/2-89/028, Ada, OK.
at, Y., Bredehoeft, J., Andrews, B., Holtz, D., and Sebastian, S., 1985.
.Ajroundwat^fanagement: The Use of Numerical Models, 2nd edition, P. van der Heijde,
If, American Geophysical Union, Water Resources Monograph 5, Washington,
Van Zyl, D., Hutchison, I., and Kiel, J., 1988. Introduction to Evaluation, Design, and
Operation of Precious Metal Heap Leaching Projects, Society of Mining Engineers, Inc.,
Littleton, CO.
A-37
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Mining Source Book
Appendix A - Hydrology
Ward, R.C. and Loftis, J.C., 1986. Establishing Statistical Design Criteria for Water Quality
Monitoring Systems: Review and Synthesis, Water Resources Bulletin, vol. 22, no. 5, pp.
759-767.
Ward, R.C., and McBride, G.B., 1986. Design of Water Quality Monitoring Systems in New
Zealand, Water Quality Centre, Ministry of Works and Development, Publication No. 8,
Hamilton, New Zealand.
Water Pollution Control Federation, 1969. Design and Construction ofSjanitaryjjja' Storm
jj^if-jjiSj!'-)^ , r^v!-^":
Sewers, Manual of Practice 9, American Society of Civil EngineSiMilual of
Engineering Practice No. 37, Washington, DC.
Weibull, W., 1939. A Statistical Theory of the Strengthjplaterials,
Handl, Stockholm, vol. 151, p. 15.
Wright-McLaughlin Engineers, 1969. Urban Storm Dr<
and 1975, Denver Regional Council of Go vermin
Yeh,G.T. 1987. 3D-FEMWATER: a three dimensij
through saturated-unsaturated media, O
2904.
Yeh, G.T., undated. AT123D. Original
available from the International!!
round jfffter
Mines, http://www. mines.c6lorado.edt
Yevievich. V.. 1972. ProbabilitvmndStatic
]eria Manual, Revised 1969
CO.
sel of water flow
y, Publication No.
on of the software is
"Center, Colorado School of
Sfsoftware/igwrncsoft/atl 2:
f
2/ogv, Water Resources Publications.
Fort-Collins. CO.
A-38
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Mining Source Book
Appendix B - Receiving Waters
LTERS
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Mining Source Book
idixB-Ri
Table of Contents
1.0
2.0
GOALS AND PURPOSE OF THE APPENDIX.
4.0
5.0
REGULATORY AND TECHNICAL BACKGROUND FOR DESIGNING A WATER
QUALITY ASSESSMENT PROGRAM Jitf 2
2.1 Mining Impacts on Water Quality *.'.. .-. .< 2
2.1.1 Disturbance Activities ~. ..*'.. A 3
2.1.2 Processing Activities f^... *: ,3
2.1.3 Waste Disposal Activities *?*. i....f. >. -if 4
2.1.4- Support. Activities /. : .\qWJfr^-.-&'. 6
2.2 Water Quality Standards ^ ™. ... 6
2.3 Processes that Affect Contaminant Dispersal . /. .' j^' 8
2.3.1 Climate ,..,..\ 8
2.3.2 Geology !...,:/ \ 8
2.3.3 Surface Water Hydrology and Rydrogeol0gy>'. 10
2.3.4 Aqueous Chemistry -^ • • ^— 9
2.4 Using the Watershed-Based Ay&Utfbt^f * '••* 11
2.4.1 Determining Pre-MjjBjag Back^EcniB^fcter Quality 11
2.4.1.1 Natural Ballgroundjp 11
2.4.1.2 Effects QjffistoriCj^nin Anthropogenic Disturbancei3
^ *^
3.0 DESIGNING A WATE
3.1
G PROGRAM 14
15
16
16
16
17
quency 18
Diversity of Biota 18
19
4.1 Tributaries and Ground Water to Surface Flow 19
TranslatJps for Dissolved to Total Recoverable Constituent Concentrations ... 19
Comp|iig Metal Loadings 19
Characterization and Data Analysis Issues 20
Below Detection Limit Values 20
Using Existing and Historical Data Sets 21
Geochemical Modeling 21
Fate and Transport Modeling 22
Other Analysis Techniques 24
GUIDANCE FOR PREPARATION OF A QUALITY ASSURANCE PROJECT PLAN
(QAPP) 24
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Mining Source Book
Appendix B - Receiving Waters
5.1 Overview of the Process for Developing a Monitoring Plan 24
5.2 Components of a QAPP 25
5.2.1 Project Management 27
5.2.2 Measurement and Data Acquisition 29
5.2.3 Assessment and Oversight 31
5.2.4 Data Validation and Usability 32
6.0 REFERENCES f J^/ 34
List of Tables ;r ;
B-l. Example Reagents Used at Metal Mines ,. i »
B-2. Water Quality Parameters Typically Measured A-Proposed'Metal Mining
List of Figures
^y ^ '' A
B-1. Conceptual Physicochemical Model of Metal Transport1!!}. a^Biyer from
Schnoor(1996)
B-2. Example Flow-Chart for Developing (faafr
Dissmeyer, 1994)
B-10
B-26
B-ii
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Mining Source Book
dixB-Rc
• Watt
1.0 GOALS AND PURPOSE OF THE APPENDIX
The primary goal of this appendix is to outline the rationale and methods to characterize
water quality in and around a proposed mine site. It is intended to be used in conjunction with
other appendices in this source book to which the reader is referred for more detailed
information. Relevant appendices include Appendix A, Hydrology, Appendix E, Wastewater
Management, Appendix F, Solid Waste Management, and Appendix H, Erosion and
Sedimentation. Background materials in this appendix review how mining activities can impact
water quality, describe how water quality standards are developed, outlrae, general processes
related to contaminant dispersal, and summarize important aspects
evaluation. The background materials are followed by a sectioft m
of developing a program to monitor water quality. A section on data,
information for modeling water quality data. The appendix conclude! by revj
important aspects of monitoring and quality assurance as needed lor NEPA
purposes. ~ * '
V V
Surface and ground waters that receive treated and untreated discharges from mine sites
are referred to as "receiving waters". Point source discharges toieceiving waters are regulated
under Section 402 of the Clean Water Act,
Discharge Elimination System (NPDES) pe:
is protecting the quality and designated Ui
of mining operations on receiving watery
baseline receiving water data. Becausi
the scope of specific water quali
ensure that data will serve all inti
manner. Receiving water quali
including:
whic
the preparation of National Pollutant
ct of ti% NPDES permitting process
•edict the potential impacts
adequate discharge and
many, it is important to assess
prior to beginning data collection to
iey will be collected in an efficient
for a variety of other purposes
iitions to support calculations of NPDES permit limits,
-specific criteria,
scoverable translators,
: trading,
lity of the affected environment for NEPA analysis,
/e impacts under NEPA,
Predicting er^Riental consequences of the proposed action and alternatives under
NEPA,
Assisting jjpconducting watershed analyses,
remedial activity in impaired watersheds, and
ing long-term trends.
guidance is focused on characterizing water quality at proposed mines. Although the
term "receiving water" is used throughout, the methods and techniques described can be applied
to any surface or ground water and are not restricted to waters that will receive direct discharges
of mine effluent. As part of this analysis applicants may be required to understand the
interactions between surface and ground waters and characterize other physical and biological
aspects of the aquatic environment. The concepts and guidance presented herein also are
B-l
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Mining Source Book
Appendix B - Receiving Waters
appropriate for surface water and ground water quality monitoring at other stages of a mine's life
cycle, including operation, closure, and post-closure. In these settings, water quality data can be
used for compliance monitoring, trend monitoring, monitoring the effectiveness of Best
Management Practices (BMPs), and establishing and verifying any permitted mixing zones.
In 1997, EPA released the "Hardrock Mining Framework", a document that outlined the
Agency's approach to dealing with environmental concerns at hardrock mining siteji. This
document acknowledged that recent national initiatives were directed toward ensuring that point
sources of pollution were addressed on a watershed basis. In addition, the Framework
recognized that the watershed approach could be an administrative meaas to reduce pollutant
loadings on a cost-effective basis. Consequently, this apr^ejlafx stresses the usex>f the watershe
approach to determine receiving water quality. Jill:/ /'
2.0 REGULATORY AND TECHNICAL BAC
WATER QUALITY ASSESSMENT PROG
This section briefly discusses technical and regjulatory
consider when designing a program to assess wategiHfty. It be;
FOR DESIGNliff
water quality impacts that can occur as a res
regulatory development of water quality
dispersal, and discusses the watershed aj
proposing new or expanded mining projlcts
quality of surface and ground waterjrelspurces
fully describe the types of impacjffiilt the rawe may c:
2.1 Mining Impacts
A«
with hardrock
important to
cribing the types of
riefly summarizes the
§ that affect contaminant
ssment. Applicants
lly characterize the existing
that an EA or EIS will be able to
; impacts to water quality, the diverse activities associated
[ into four mam areas. Disturbance activities include the
development of inm^fjfls, shafts||iid,aefits and surface disruptions associated with mine
development andfaciJity construction (e.g., grading, road construction, impoundment
construction, fbundatioi^m^^tion, soil snipping, and pipeline and powerline construction).
Processing activities in^^^^Pconstruction and operation of crushing and milling facilities;
flotation concentrators; smeJiers and refineries; heap and dump leach facilities; vat and tank leach
plants; water treatment facilities; and carbon stripping, zinc precipitation, and solvent
extiaction/electrowinning plants. Waste disposal activities include the construction and
operation of waste rock dumps, overburden piles, tailings impoundments, and slag piles and
other process waste. Support activities include those actions required for day-to-day operation of
the mine such as equipment maintenance, fuel storage, wastewater treatment, and laboratory
analysis. EPA has prepared a series of Technical Resource Documents that summarize the
extraction and beneficiation of lead-zinc, gold, copper, iron, uranium, gold placer, and phosphate
and molybdenite ores. They can be obtained from the EPA Office of Solid Waste webpage
(http://www.epa.gov/epaoswer/other/mining.htm).
B-2
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Mining Source Book
idixB-Re
;Watc
and increasin!
2.1.1 Disturbance Activities
Disturbance activities increase the potential for surface or ground water impact by
exposing mineralized rock, disturbing native soils and vegetation, altering slope angles, and
modifying watershed and aquifer characteristics. Mine pits, adits, shafts, and open cuts that
expose mineralized rock have the potential to produce increased loadings of metals, dissolved
solids, suspended solids, and acidity to surface waters. The construction of roadsfutility lines,
and facility foundations and stripping activities associated with the devejcipneni-of mine pits and
the construction of mine processing, disposal, and water mapgement^|||ef increase the
potential for sediment contamination. These activities altejliikural wfi^^sii;eharacteristics by
, . S#%t0&-Jif..''' _!;"W,?.V\Y''' ' '*'L;^.Z%&* • -
increasing runoff, decreasing soil cohesion and infiltrat
erosion. Potential mining impacts associated with eros
more detail in Appendix H, Erosion and Sedimentatior
The types of constituents that can be released d
depend on the nature of the mineralization and the mi
increase the concentrations of suspended particles am
Mn, Hg, Ni, Se, Ag, Zn), major cations (e.g.,
(e.g., nitrate, sulfate, chloride, carbonate) thai
surface waters. Constituent concentratio:
naturally occurring compounds or by rnejilssoluti
B-l), that are used during disturbance jJSavities
disturbances can result in the prodi
and sedimentatio&l
mine drainage or acid rock drai
which commonly occur in mini
atmosphere^Jhe acidity
surface f(
:h
Distur
through pre
layers.
bility to
iibedim
wing disturbance activities
^Mining disturbances may
Cr, Cu,Fe,Pb,
I* Na), and anions
tol dissolved solids in
[fssolution or retransport of
as blasting residues (Table
'ace and underground
s phenomenon, referred to as acid
minerals (pyrite and marcasite),
to the oxidizing environment of the
and underground workings can impact
by lowering pH .and increasing the
ed surfaces and maintained in solution.
inants to surface and ground waters primarily
mine water, or disruption of aquifers and their confining
of
Processing acjjpties increase the potential for surface water impact by creating facilities
;h metals arjfflrocentrated to values significantly above those in the ore, dissolving metals
^ ..ng metal-rich ore into fine particle sizes, and storing and using large
,_ fents that can potentially degrade surface water quality. Depending on the type
id concentrating process employed, a mine may construct ore stockpiles to assure
^^ A, AAAAAAJbJbJtk^ »*fc^^* ^^^jfc»^ -»«^» ^--— — — ^^ p — — — Ji * ' •* *
consistent feed to a mill. Pad and dump leaching facilities have associated impoundments to
store barren and pregnant leach solutions, pipelines to transfer solutions between storage ponds
and leach pads, and leachate and seepage collection facilities.
B-3
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Mining Source Book
Appendix B - Receiving Waters
Contamination from processing facilities can occur in many forms that depend on the
type of ore being processed, the type of on-site processing, and the specific mine design.
Consequently, the list of chemicals used at a mine site can be extensive and may include flotation
reagents, frothing and collection agents, scale inhibitors, flocculents, thickeners, leach solutions,
and leachate neutralizing solutions. Table B-l gives examples of the types of processing
reagents that may be used by mining operations; it should be recognized that this table does not
provide a comprehensive listing.
Processing activities can release contaminants to surface wati
include spills of reagent materials or processing fluids (e.grpipeline
vanity of ways that
"leaks at
processing facilities (e.g., liner tears), storage pond overflows (e.g., d!
facility failures (e.g., slope failure of a leach dump). Contaminant
(release directly to surface waters) or indirect. Examplefpbf indirej&eont
include infiltration to ground water that exchanges seepage"1
which discharges to surface water, and seepage impoundment dams and berms.
events), and
direct
iways
2.1.3 Waste Disposal Activities
Waste disposal activities increase the potpjfi^i surface^
permanent features in which waste materials
leachable metals, acidity, cyanide or other tfmt conl
years after mining ceases. Examples ofJnese faciHjfes:
impoundments, and spent ore piles. Pe^riptionjjpi the
mines sites are given in Appendix ~jjj$qlid Warn! Manage
:t by creating
ste matel|llrcan serve as sources of
jd fiBfr-grained sediment for many
: rock dumps,
yaste disposal facilities used at
znt.
Waste disposal facilitiesj^an imp;
metals, and other cont
which thes«:ii$terials
procedures
grained materi
^^
potentially
term, wastefock
material can contribute '
through the release of sediment,
available to the environment
grain size and mineralogy), the means by
(e.g., cyanide or acid leach), and the types of closure
- ^^
, neutralization, capping and revegetation). Fine-
a significant source of erodible sediment that
^^
sited in stream beds by surface runoff. Over the long
impoundments, and spent ore piles that contain sulfide-bearing
receiving waters through the oxidation of pyrite and marcasite
as described in Appendix F, Solid Waste Management. Acid leachates produced from these
materials facilitate the dissolution of the metals listed in Section 2.1.1, Disturbance Activities,
Closed cyanide and acid heap leach units may contain residual cyanide and cyanide by-products,
or acidity that can he released to receiving waters if the heaps are not properly rinsed and
neutralized (Simovic et al., 1985).
Contaminants can be released to surface waters in a variety of ways that include physical
failure (e.g., breach or sloughing of a tailings impoundments), seepage (e.g., below an
impoundment dam), saturation and overflow of lined facilities (i.e., the "bathtub" effect), and
erosion by wind and water (e.g., gully formation during storm events). Contaminant pathways
can be direct (release directly to surface waters) or indirect. Examples of indirect contaminant
B-4
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Mining Source Book
Appendix B - Receiving Waters
Table B-l. Example Reagents Used at Metal Mines
Disruption Activities
Blasting Agent
Ammonium nitrate & fuel oil (ANFO)
Processing Reagents
Flotation Reagents
Alkaline sulfides
Sodium cyanide
Sodium ferrocyanide
Aliphatic alcohol
Phenol
Ethyl and amyl xani
Alkyl dithiophosp]
Methyl isobutyl carbi
Aerofloats
Copper sulfate
Zinc sulfate
Sodium sulfide
Kerosene
Phosphorous pentasulfide
"'" ''•• • - '
Sodium diethyl phosphorodithioate
Thiocarbamate
Pine oil
ichromate
hydrosulfate
bisulfate
Solvent Extraction - Electrowinning Reagents
Sulfuric
Oxim«4»rnpoi
teric fli
'ative
irbon distillates
ilt sulfate solution
iethylene glycol butyl ether
Miscellaneous Concentrator Reagents
Polyphosphate
Polymeric and organophosphorous
compounds
Leaching Reaj
Sodium cyanide
Leach
Hydrochloric acid
litric acid
Lead nitrate
Zinc
Sodium sulfide
frogen peroxide
ilorine
Sodium hypochlorite
Lime
Sulfur dioxide
Copper
Support Activities
Gasoline
Diesel fuel
Gear oil, motor oil, hydraulic oil
Lubricating grease and oil
Antifreeze
Paraffinic, napthenic, and aromatic
hydrocarbons (solvent)
Propane
Reagents
Ion Exchange Reeenerants:
Hydrochloric acid
Sulfuric acid
Sodium chloride
Descalants:
Calcium sulfate
Calcium carbonate
Silicon dioxide
Chemical Precipitation Reagents:
Lime
Alum
Sodium hydroxide
Calcium hydroxide
Hydrogen sulfide
Calcium sulfide
Sources: Coeur Alaska. Inc., 1997; U.S. EPA, 1994a, 1994b, 1994c, 1998a; Knorre and Griffiths, 1985; Montgomery
B-5
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Mining Source Book
Appendix B - Receiving Waters
pathways include infiltration to ground water that exchanges with surface water, seepage to soil
or bedrock which discharges to surface water, and seepage through or below impoundment dams
and berms.
2.1.4 Support Activities
Support activities can increase the potential for receiving water impacts through facilities
that use and store chemicals and generate waste materials. Support activities can-release
contaminants to surface waters through a variety of means that include spills and leaks from fuel
handling and storage facilities, seepage from solid waste landfills, and seepage and runoff from
equipment maintenance facilities. Contaminant pathways may "be direct or indirect. Examples,,
indirect contaminant pathways include seepage to soil or bedrock from abcwe-ground fuel stqzage
tanks and runoff from soils contaminated with solventsw degreasing/agents.
2.2 Water Quality Standards
An important aspect of mine review for EPA is
adversely affect water quality. One measure of this
of water quality standards. This type of analysis j
streams and determining the impacts they woj
potential for water quality impacts, the wa$erjuaiit
must be determined. Water quality standards are
lysis is
characti
ater q
.er a project will
to cause exceedances
fential discharges to
'rior to evaluating the
ly to the receiving water
or Federal law which
Waters of the U.S., (2) water
s based upon their uses, and (3)
consist of three components: (1) designated beneficial uses
quality criteria (which may be nun^pcfor n
antidegradation policies. State w^fejualitv^indards implementing provisions are
approved by EPA and are codifiecnn Statef^»lation^^[t is essential for a mine to obtain the
most up-to?date state water qwatfey since they often change on a
periodic basis. Many of IjhesenJejgulationsa^^^w available on-line. More information regarding
water quality standards isprowtedrin EPA's Water Quality Standards Handbook (U.S. EPA,
1994d). < - ^
Under the Clean Water AcffSfcTi State must classify all of the waters within its
boundaries by their intended|&f [see §303(c)(2)]. Once designated beneficial uses have been
determined, the State mi$pi|atish numeric and narrative water quality standards to ensure the
attainment and/or maintenance of the use. Designated beneficial use classifications include the
useand value of water for public water supplies; protection and propagation offish, shellfish,
araJ'wildlife; recreatiotfin and on the water body; and agricultural, industrial and navigational
purposes (see 40 CFR § 131.10 for more detail on the designation of uses). For a specific water
body, a mine can determine the applicable standards based on the designated use classifications.
Where multiple-use classifications apply to a water body (e.g., recreational and aquatic life uses),
the most sensitive use designations generally apply. Water bodies, especially minor tributaries,
may not be identified in State regulations along with their designated beneficial uses. In these
cases, States may assign to tributaries the same designated uses as the larger water body that they
flow into. Alternatively, they may have a general set of classifications that apply to all
unspecified water bodies.
B-6
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Mining Source Book
Appendix B - Re
!\Va
EPA recently published an updated listing of nationally recommended water quality
criteria for 157 pollutants (U.S. EPA, 1998b). States may either adopt these criteria or develop
alternative criteria that protect the designated uses of their waters. In such cases, the Clean Water
Act requires States to use sound scientific rationale to develop their water quality criteria.
Criteria may be expressed as constituent concentrations, levels, or narrative statements that
represent a quality of water that supports a designated use. Criteria may be developed for acute
and chronic toxicity to aquatic organisms, agricultural and industrial uses, and human health
effect protection. Criteria, which are developed for both fresh waters and saline waters, may be
designated in the form of dissolved, total recoverable, and/or total constiloent!iewicentrations.
Acute criteria are based on one-hour average concentrationsjhat cannM|>i^£ceeded more than
once every three years on average, whereas chronic criterifiipPbased''oliOTiKlay average : „
concentrations that cannot be exceeded more than once e^fry three ye^rs % average. While £.-
some States use the same water quality standard valuesj^r all streams assigned an individjoal"
designated use, others depend on stream-specific cor
toxic under low hardness conditions and the applicable!
receiving water. Other standards (e.g., turbidity and tem|
from natural conditions. For carcinogenic constituentsjl
authorities to determine the human health risk factors Hat appf
baseline data for water quality parameters, especjgjjf^ghey relate to p
':...';. •$£$*
Fojcexample, some metals are more
depend on the hardness of the
ay be based on deviation
d check with State
for representative
fes in flow, is obvious
and should be considered in developing baselk
monitoring programs.
Many states have specific proce
natural dilution of discharges by strea
individual pollutants and contributions7]
to est
low, taipg into
Dnes," which allow for the
ration background levels of
3m o|par discharjlrs. A mixing zone is a limited area
or volume of water where initialisation of^pscharge^pes place and where numeric water
quality criteria can be exceededjftt are prevented (U.S. EPA, 1994d).
Mixing zon^ypically based (e.g., the 7Q10 flow in a
7Q10 conditions approach zero, many do
not quality standards must be met at points of discharge.
Operators
in the State wal
the penmttij
jse mu
jstanc
just submit an application following procedures outlined
* applications require applicants to work closely with
Ltes have a antidegradation requirements that prohibit discharges from
[ing existing except under specific conditions. These policies are designed to
;t existing instreajjluses and water quality and to maintain and protect waters of exceptional
that representjfoutstanding National resource. In cases where water quality would be
ished, Stotes^p|frrequired to assure that water quality would remain adequate to fully
fgnated uses.
State water quality regulations include provisions for developing site- or stream-
specific standards and reclassifying (i.e., changing the designated uses of) water bodies.
However, there is almost always a significant burden on the applicant to demonstrate the need for
such changes. Operators are encouraged to work closely with States and EPA in determining
whether site-specific standards/reclassifications are possible for a site and the supporting
B-7
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Mining Source Book
Appendix B - Receiving Waters
information that would be required. EPA must approve all changes to State water quality
standards, including site-specific standards and reclassifications.
2.3 Processes that Affect Contaminant Dispersal
The processes that affect contaminant dispersal depend in part on site-specific factors
such as climate, geology, surface and ground water hydrology, and water chemistry. These
factors control runoff, infiltration, weathering and erosion, and the dissolution andirttenuation of
metals. One goal of watershed-based analysis is to identify the process^sihatshsve a primary
controlling influence on water quality throughout the watershed.
2.3.1 Climate
Climatic factors determine seasonal flow in a
and ground water recharge (see Section 3.3). Changes'
quality by affecting the extent to which metals are dilute!
which sediment and metal-bearing particles are erode
impact that may be caused as oxidation products are periodi
and tailings piles. These effects need to be quantij^^kthat nai
contributions to water quality can be disting
id affect seas
[tion and runoff calliffpact water
wnstream flow, the degree to
downstream, and the
>m waste rock dumps
ing-induced
2.3.2 Geology
areas;
ifees in 14
Surficial geology in miner;
Variations can be manifested as c|
character of alteration, nature ofSfenerali
over and through differen
particularly ;w||a regan
example,.'v^foiiiKiestone^^^^^ke are present in a watershed, surface waters may contain
* 7 •_ •". ^; .=•;-.-- ^k •* 7 *
• alkalm^^HB^h concentrations of dissolved Ca and Mg. However, in
id soil
Dns,
uld be ejjpected to vary at the watershed scale.
type, djph and character of soils, degree and
JJJMJfcffi
andjgragnt of fracturing. Surface waters flowing
e different constituent concentrations,
alinity (e.g., Stumm and Morgan, 1996). For
a different porfiill
lower bicarboraate*
ie>same waf
I-JV-'I'.
co
at is underlain by granite, waters may have much
ations.
In most mine are^^e^he intensity of mineralization and the types of metallic minerals
present are likely to change^m location in a watershed. Variations in the style of rock
alteration (e.g., phyllic vs. propylitic) can cause portions of a watershed to produce surface and
ground waters with different water quality characteristics (Smith et al., 1994; Mast et al., 1998).
Mountainous terrains may expose the transition from primary hydrothermal sulfide minerals to
secondary oxide and carbonate minerals. The different solubilities and acid generating
capabilities of sulfide and oxide minerals may produce waters with significantly different pH and
metals and sulfate concentrations (e.g., Stumm and Morgan, 1996; Langmuir, 1997). Variations
B-8
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Mining Source Book
Appendix B - Re
•Wi
in the intensity and style of fracturing, which should be expected in watersheds that host
structurally controlled mineral deposits, can lead to changes in infiltration, ground water flow,
and ground water discharge within a watershed.
2.3.3 Surface Water Hydrology and Hydrogeology
A detailed discussion of characterization and measurement of surface water;jhydrology
and hydrogeology is presented in Appendix A, Hydrology. Hydrological and hydrbjeological
processes and their accurate characterization are inherently related to the^eharaeferization and
identification of potential impacts to important resources such as receire^^ter quality, aquatic
life, vegetation, and wetlands. Watershed hydrology andj^Sgeolog|^pii|febe well .*,
understood prior to finalizing a program to characterize Reiving wa^qtiai^lfeiportant *
watershed characteristics that should be evaluated inclufj|fpeak stp|^llowJ:Hi^^B^n:dnugG^if
relations, sediment load, surface water-ground water e^^ge^jlliter table elevl^S|^9nhd
water recharge and discharge, aquifer confinement, of dewatering activities.
.iSS?;fo''S:!>
2.3.4 Aqueous Chemistry A
ic environment
The precipi
evaluate^fien asses!
solidjplicles with di
BroJIIan motion (parti
inson ami|||Hison, 1991). Under
eonsjftuent concentrations that
"9
'secondary phases precipitate
onto particle surfaces
The extent to which receiving waters disRej^^fetaminanl
depends partly on water chemistry and soil c.
equilibrium conditions, surface and groundjpillers
depend on local physical and chemical cjpiitions,,,;
from solution, and the tendency for disMved corfstituents
jAmS' jHf
(Schnoor, 1996). Figure B-l show»^>ncepl^pphysicotfemical model of metal transport in a
surface water system illustrating^^^6mple;^»teractio^piffecting concentration. In general,
waters with comparatively tow jjjJFcan of metals in solution than
neutral changes in pH, redox potential, or
other lead to dissolution or precipitation of
metal-t
precipitates
jon or desorption from bottom sediments or from colloidal
., 1988; Langmuir, 1997).
*
known to be an important process.that should be
[uality (Church et al., 1997; Schemel et al., 1998). Colloids are
ler than 1 micron that remain suspended in water due to
ive as a consequence ionic attraction and molecular collision).
idal deposition cajftccur when particles aggregate into larger masses that can no longer be
ded by molecuJJF forces. Aggregated particles that have settled to the bed of a stream can
ded duj^jfhigh flow, causing water quality to decline (Boult et al., 1994).
lloidal particles will pass through a 0.45 micron filter and will report as
Situents in water quality analyses. Colloidal particles, particularly iron
ides, readily sorb dissolved metal ions from the water column (e.g., Chapman et al.,
1983; Langmuir, 1997). Although the formation of oxyhydroxide minerals may improve water
quality by facilitating sorbtion of other dissolved metal ions, deposition of colloidal particles may
degrade aquatic habitat quality by coating substrate materials.
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Mining Source Book
Appendix B - Receiving Waters
Atmospheric or
runoff inputs
Volatiliation
Diffusion
_». to deep
sediments
Figure B-l. Conceptual physicochemical model of metal transport in a river from Schnoor
(1996). '
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Mining Source Book
idixB-Rt
•Wa
The stability of colloidal precipitates is a function of chemical parameters such as pH and
redox potential. Consequently, chemical changes occurring in a receiving water, such as in a
mixing zone, can cause colloidal particles to precipitate or to redissolve and release their
adsorbed metal constituents to solution (Church et al., 1997). For example, acidic, metal-bearing
water draining an area of quartz-sericite alteration that flows into a stream with significant
buffering capacity that is draining an area of propylitic alteration can cause iron- and aluminum
hydroxide minerals to precipitate (cf., Chapman et al., 1983; Boult et al., 1994). Even under
natural conditions, water quality in a receiving stream above a mixing zone may,have metals
concentrations, alkalinity, pH and redox potential that are different fronTwater below a mixing
zone (Walton-Day, 1998).
2.4 Using the Watershed-Based Approach
Mine facilities potentially can impact aquatic e
downstream by dispersing contaminants through recei
anticipate the environmental impact that future mining
impact that past and present operations have had on
understanding at the watershed level (Hughes, 1985).
recently was recognized in an initiative to remedi
Geological Survey (Buxton et al., 1997) and ii
1997a). ^
Water quality may vary within^watershj
surficial geology, hydrogeology, iiM^tion-rugtef relatic
land use, and anthropogenic distiiiSiRce.
a watershed is a mix of the co
watershed-teed approac
:do
Among
nature ol
tershed hydrolc
•r considerable distance's
(Salomans, 1995). To
have and to determine the
requires an
ttershed approach
" led by the U.S.
'ramework (EPA,
$?
differences in factors such as
ips, seasonal variation, vegetation,
quality in the downstream portion of
each upstream tributary. The
occurring in one or several upstream
2.4.1
recogm
wa
fcan
ound Water Quality
fo characterize baseline conditions, it is important to
>,that may influence water quality in potentially affected
jrtant of these are the presence of mineralized exposures, the
sturbances that have caused impacts to water quality, and changes
''Natural background" is a term used to describe the water quality of a
:en disturbed by the actions of man (U.S. EPA, 1997b). In contrast,
md" is a term used to describe the water quality existing in all or a
that has been disturbed by human actions. The term "baseline" is used to
quality measured at a given point prior to future disturbance and from which
be measured. Baseline values may include components of both natural and
anthropogenic background.
B-ll
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Mining Source Book
Appendix B - Receiving Waters
2.4.1.1 Natural Background in Mineralized Areas
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Mining Source Book
Appendix B - R
-------
Mining Source Book
Append ix B - Receiving Waters
understanding of the natural background conditions at the proposed mine site proved critical in
the preparation of the EIS and NPDES permit for the Red Dog project.
The Red Dog site provides an example of extremely elevated natural background metals
concentrations. In most locations, the effects of mineralization on natural background are
expected to be much more subtle. Nevertheless, even small departures are important to
recognize for the EIS and NPDES permitting processes.
2.4.1.2 Effects of Historic Mining and Other Anthropogenic Disturbances*
*$.»& v-
A If^i;/
A: /s&tfs. ,. * 9 ^" /•>
In many mining areas, historic mining disturbances^seaitly comj3i£at| Efforts to
determine background geochemical values (Church et alfjf998; '**'"
mining activities or other anthropogenic disturbances cJSialter
concentrations in a watershed by disturbing soils and si
characteristics, and creating mine pits, adits, waste roc
and other facilities that are sources of metals and other p
increased sediment loads (e.g., by removing vegetatio:
(e.g., from an adit) with elevated levels of acidity an<
deposition of leachable materials (e.g., tailings
In watersheds with numerous histo:
ground water sites that have not been afi^jpted. A
undisturbed sites may provide data thajppply o:
samples were collected and not to ti^'elitire
mining disturbances may be so in
characterize background valuesjjpunnells
determine background at dis
historical-watet-quality
complete that tifey .provict
back;
ig runoff
ilings piles, pads,
tese activities lead to
and surface discharges
stream transport and
Ap
;ult to find surface or
acquire samples from
or sub-basin from which the
it et al., 1998). In fact, historic
it it is nearly impossible to fully
view methods that can be used to
e most desirable of these is to use
ata are rarely available or sufficiently
|e assessment of pre-mining values. Consequently, three
indirect methods have, been provide some measure of understanding of natural
background condMoas^One metia0d ejlrapolates data from an analog site in a nearby
undisturbed watpcshedjpi%hes, 19i^Runnells et al., 1992; Bowers and Nicholson, 1996).
Such sites must have geological and hydrological characteristics that are similar to those of the
watershed of interest. Although analog sites can provide useful data, it is usually difficult to find
an exact hydrologic andnydrogeological match (Runnells et al., 1998). A second method uses
equilibrium geochemical models to predict the maximum constituent concentrations that can
occur in water that is ^equilibrium with rock and metallic ore minerals (Runnells et al., 1992;
NoHpstrom et al., 1996). Geochemical models require that users establish boundary conditions
and make other assumptions (e.g., regarding pH, redox state, etc.) that cannot be easily tested or
verified (Runnells et al., 1998). A third method uses a statistical approach to identify the natural
background component in water from disturbed areas (Runnells et al., 1998). For example,
probability graphs (Stanley, 1987) have been used to identify natural background values in
anthropogenically impacted ground waters at the Bingham Canyon Mine in Utah (Runnells et al.,
1998). Although statistical methods are capable of identifying multiple concentration
populations, the process can become very complicated for areas where surface waters are
B-14
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Mining Source Book
Appendix B - Receiving Waters
impacted by numerous mining features. Some of these challenges are described by Moore and
Luoma (1990) for the Clark Fork River drainage in Montana.
Church et al. (1998) describe an innovative, indirect approach for determining the extent
to which historic mining activities may have affected baseline metals concentrations in a
watershed. Their method is to collect and analyze sediment cores from stream deposits formed
prior to the onset of mining activities and to compare these values to those obtained, from
recently formed deposits. In addition to metals and other constituents, sedimentsfcan be analyzed
for signs of biotic life. This approach provides data only about stream s^dimeat compositions
and does not provide direct information on water quality. *"* "
In addition to mining, there can be a wide range,(pother existing a^ff-taaces in a
watershed that affect water quality. Understanding thejglects of |^i^sturb^m|^s:^^ntial to
producing an adequate characterization of baseline conolions. TJpspending on mel^^cific?
setting, this may necessitate collecting samples of runo'fCand^seepage, pore water^andlsolids. In
some cases, water quality may be controlled by a set of inle^five processes that need to be
recognized in order to predict future water quality chan^^ Bbr example, Paschke and Harrison
(1995) describe an area of historic mining in Coloradcrin whicrwnelaitcansport in a stream is
affected by ground water interaction and seasonaJUguEta^e of a nateaiAretiand. Without such
information, it may be impossible to predict aj^^rapH^H^ incremental effects of new
operations.
3.0 DESIGNING A WATER^C^LITY^ONITCEG PROGRAM
Several factors must be de?^^8 and establisnin§ programs to sample
and characmze baseline^Mpality conduct long-term water quality
proposed or existing mine site and its
relation to the watershed, natural drainages, aquifers, and
ground or existing discharges and expected areas of
infiltration; and the mineralogy of associated waste rock and
lemiclSInd hazardous materials that will be associated with the
ore; (4) the
operatic^
gro
thedes
ater in potent
of all surface waters in the watershed; and (6) the utilization of
:ted aquifers. A complete water quality data set will expedite
fshing water-qualijpppld effluent limits and total maximum daily load allocations, which
required by a Nffional Pollutant Discharge Elimination System (NPDES) permit (EPA,
W
lonitoring programs should achieve the following objectives:
^Syiii^'
^Define spatial differences in water quality parameters and constituents throughout the
watershed.
• Define temporal differences in water quality that result from general changes in
seasonal flow.
• Define differences in water quality that can occur during major climatic events, such
as low probability storms or droughts.
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Mining Source Book
Appendix B - Receiving Waters
• Define the effects of mining operations and associated accidental or permitted
discharges on water quality.
• Define and monitor the effectiveness of applied Best Management Practices and
mitigation measures used by the operation to protect water quality.
3.1 Sampling Locations
A surface water sampling program should define the number an4Jocation$|Sf monitoring
stations on a watershed basis. Monitoring stations should be establishe|p« alttriajor tributaries
in a watershed to quantitatively measure spatial changes in jvater qua^J|j^|result from
variations in geology, soils, mineralization, and land covejatf from hS^||fcing operations,^
and other land use disturbances. Existing water quality sfpuld be
mixing zones and at downstream points of compliance||Ionsequejj^ mori
should be established above and below a proposed or site and imf
the confluences of all major tributaries. These locations
Hid in potential
define the contributions of different flows to downstrean
changes that occur as two flows mix together. To the 0Site
stations should be located on straight, hydraulically sttble stre?
and large depositional areas. This will minimizeJfa^^g|ibility
due to streambank erosion, sediment (thah
Surface water monitoring stationjpfso sho\
discharge points and all hydrologic strucl
detention/retention facilities, tailiq^fiposal
ow
the types ofoHffieeded to
and the water quality
extent, monitoring
at are free of pools
may vary over time
igration.
fabove and below permitted
diversions, storm water
2S, sue!
Duties, ojjprocess ponds. These stations are
usually required for compliance jaaffctoring. ^ft is important to note that ambient and compliance
monitoring programs should beJ|P&blished^th common objectives, measured constituents,
sampling frequency, labora^fcp;ocedures;"&dcd^Bcfion limits.
Ground water quali*yjm^iitoring locations should be established in each potentially
affected aqi^^,afer:considering"fliejlithology and permeability of the aquifer; how, in what
direction, and at what speed waterd3o^€irough it; and whether exchanges occur with surface or
other ground waters. £|pecial considerations may be required for shallow aquifers that exhibit
seasonaLflow in respansbto spring snowmelt or winter freeze. In general, ground water
monitoring requires that data*bVcollected from wells that are located both up-gradient and down-
gradient of potential contaminant sources. Existing water quality should be well established in
areas that could be impacted by seepage from mine facilities. Numerous publications are
available that describe fee design and construction of monitoring wells and provide guidance on
programs to monitor ground water (e.g., Nielson, 1991; U.S. EPA, 1993a; 1993b).
Lakes, estuaries, bays, and other tidal areas have unique chemical, physical, and
biological characteristics that need to be identified prior to establishing sampling locations. For
lakes, this likely will require applicants to complete limnological studies that characterize
seasonal biological processes and identify physical phenomena such temperature stratification,
evaporation, degree of mixing, sediment-water chemical exchange, chemical stratification
(particularly dissolved oxygen), retention time, and ground water inflow (e.g., Thomann and
Mueller, 1987; U.S. EPA, 1990). Additional factors such as tidal currents and temperature,
B-16
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Mining Source Book
idixB-Rc
• W
salinity, and density gradients are important in estuaries, bays and other near-shore waters (e g
Thomann and Mueller, 1987; U.S. EPA, 1992). These types of data are fundamental for
establishing sites that will provide representative samples and they form a basis for interpreting
the results of water quality analyses.
3.1.1 Mixing Zones
Proposed mixing zones, as defined in Section 2.2, should be characterized as part of the
monitoring program. Importantly, mines may be located in areas withMghly variable flow
conditions that can cause the effects and extent of mixing to change significantly with time. In,
this regard, water quality immediately above a proposed tratfall and mixing zone should be
assessed at the time of highest risk. For many dissolved constituents?this typically occurs raider
conditions of low flow. In contrast, highest risk for coB^tawnts-ferried as suspended particles
occurs under conditions of high flow. Developing an of higlrVisk
conditions requires that data be collected for as long as characterize
•seasonal and annual variations in runoff and stream environments.
Applicants requesting mixing zones in lakes, estuariesfbays, may need to
conduct limnological or oceanographic studies thjMBBtopterize and chemical nature
of these environments.
Most States allow mixing the spatial dimensions of
permissible zones. Each is reviewed o«'case-h«ase regulations regarding the
dimensions permitted for flowing jjjl!e|s (riva^and streajijl) may differ from those for still-
water bodies (lakes, estuaries, co^w'water^^pplica^^hould check with State personnel
early in the NEPA and CWA of data that will be required for a
mixing zonjjjtpplication. is available in U.S. EPA (1991).
:ed quality of surface and ground waters form the
of potential impacts rest. Consequently, it is vital that
T quality. For ambient waters, it may be necessary to use
ysis techniques to measure very low concentrations of trace
The da
foundation
these
speciajpaniple collecti
co»Kients.
Sampling Methods
p
_techniques can be used to collect samples of flowing or still surface waters
from the vadose and saturated zones. Depending on their intended use,
^^^ - ybe taken as grab samples, depth integrated samples, composite samples, or
continuous samples. Descriptions of sampling techniques and evaluations of the utility of each
are not presented herein. Instead, the reader should consult one of the many sources dedicated to
these topics such as Hamilton (1978), Canter (1985), Nielson (1991), U.S. EPA (1990; 1992;
1993a; 1993b), or U.S. Geological Survey (1998).
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Mining Source Book
Appendix B - Receiving Waters
Many EPA analytical methods require that samples be filtered in the field through a 0.45
|im filter. Depending on the constituents that will be analyzed, samples are then treated to
prevent precipitation of metal compounds, volatilization of organic constituents, or the
production of hydrogen cyanide. These methods are outlined in U.S. EPA (1983; 1986) and
briefly described in Appendix C, Characterization of Ore, Waste Rock, and Tailings.
Importantly, the quality of trace metal data, especially for metals concentrations below 1
part per billion, can be compromised by contamination that occurs during sampl©f©Ilection,
preparation, storage, and analysis. EPA has developed Method 1669 S|pa|ica|Iy'for collecting
samples of ambient waters that will be analyzed for trace metals (U.S^|^fe§996i). The method
f J />•"';•;,- v ataaK-Tl**™•''"<'-:" **•-:»?:*•-
outlines procedures for collecting, filtering, and preserving;
analyzed using low-detection-limit techniques (see AppentSix C,
Rock, and Tailings}.
that will be
•e,
The adsorptive behavior!
and soils ha^e different c
characterisfes%cross a
dissolved miiKiPtese data?
^..can
watershed.
3.2.2 Selecting Parameters
The specific water quality parameters that shot
depend on the site geology, soils, climate, and vegetal'
waste rock materials; process methods and cher
uses of and the water quality criteria that;
be considered when selecting sampling
of metals analyzed should be based on'.
geologic studies, including the miners
typically measured at metal mining^pSrations
iy a given operation
pf the mined ore and
If'and the designated
iese factors must also
sis procedures. The suite
ine sampling and site
;k. Table B-2 lists constituents
associated with an ac
as a function of pH and redox potential,
ities. Due to changes in soil
by soils and sediments will also vary. For
need to analyze samples for both total recoverable and
delineate the chemical behavior of specific metals in
ferine spatial variations in metal loads within the
assess impacts to receiving waters that could be
ischarge of pollutants.
TableTB-2. Water Quality Parameters Typically Measured at Proposed Metal Mining Sites.
£••• • • /».
V TCLP Metals
v&
Arsenic
Barium
Cadmium
Chromium
MajorCations
Lead
Mercury
Selenium
Silver
Aluminum
Antimony
Beryllium
Cobalt
Copper
Other Metals
Iron
Manganese
Molybdenum
Nickel
Zinc
Major Anions
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Mining Source Book
Boron
Calcium
Magnesium
Other
Acidity
Dissolved Oxygen
Total Alkalinity
Potassium
Sodium
Constituents
Free Cyanide
Total Cyanide
WAD Cyanide
Ammonia Nitrogen
Bicarbonate
Carbonate
Chloride
Fluoride
/vppenaix tt- Receiving waters
Hydroxide
Nitrite Nitrogen
Nitrate Nitrogen
Orthophosphate
Sulfate
Other Parameters A
~~~" " ~m;w
Conductivity
Eh
M
Taa§a2|ature ^
A '"-I'Xls A^T?
?.y '•>; .O'/'VIS.
Jfc Total Dissolved Solids
.4 Total Hardness
Suspended Solids
*
3.3 Sampling Schedule and Frequency
* 5 «,*
«'' ^* I*
Sampling of all monitoring stations should occur at alseqwency that permits accurate
definition of the changes to water quality that occur seasonally and iaiesponse to short-lived
changes in flow. Several years of sampling required to accurately define
monthly, seasonal, and annual variations. schedule should be designed to
ensure that water quality data are collectedJIrSm occur. This will provide
a representative set of data that can be to supjilrt requirements. Typically
programs will need to utilize a combinftion of j|podic an^^^rtunistic sampling. Periodic
samples are collected on a regularj|iiedule, f|^xample^onthly. Opportunistic samples,
the yjjljjf are usec^p define water quality that occurs during
or events. For example, opportunistic
; to determine those parameters that are
,olved c^^^raents) and those that occur at increased
which should be collected throui
extremes in the seasonal
sampling s^rid be
diluL.^&owC
concennS^^Mgally
differences 11
define water
opportunist
effect! vgpeis of wate?
and sOTmentation.
ility
lemer
Mistituents). Opportunistic sampling also can help to define
||ween high and low stream flow conditions and to
termittent streams. During high runoff events,
usedWestablish a baseline from which to evaluate the
:tures and BMPs designed to minimize impacts from erosion
:•»
For some locatijfls, applicants may find it useful to link sampling schedules to stream
i defined by sggftraal hydrographs. This approach could prove especially beneficial in
beds that 'variety of climatic zones due to topographic factors or proximity to coastal
irsheds with severe climates. For example, orographic effects, which cause
/increase with elevation in a watershed, are especially important to consider in
coastafand mountainous areas, such as southeast Alaska. Alternatively, mines that are located in
mountainous terrain or in northern climates may experience winter periods with extremely low
stream flows or freeze-over, followed by periods with excessive runoff during the spring thaw.
Mines located in arid or semi-arid areas may experience summer periods with low flow and short
periods of intense rainfall that locally produce large discharges. These effects can impact water
quality and contaminant dispersal as described in Section 2.3.1.
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Mining Source Book
Appendix B - Receiving Waters
3.4 Assessing the Health and Diversity of Biota
In addition to characterizing the chemical and physical quality of surface and ground
waters, applicants will need to provide an analysis of the health and diversity of biota in
receiving waters. These analyses are described in more detail in Appendix G, Aquatic
Resources. For proposed mining operations, existing streams may be severely impacted by
historic activities. Hughes (1985) presents a methodology for determining the health and quality
of aquatic life in streams in which this has occurred. His technique relies on identifying control
streams in nearby unimpacted watersheds that have similar watershed characteristics to the
impacted stream. Control streams are used as analogs fronxwjiich the potential biotic and habitat
conditions of the impacted stream are estimated.
4.0 DATA ANALYSIS
W£
Preparation of Environmental Impact Statements i
analysis of water quality and potential impacts that
section describes the types of data analyses that may e reqi
4.1 Contributions of Tributaries and Gi
permits will require an
ae proposed project. This
SPA and the CWA.
Applicants may be required to cqjftuct an the contributions of
tributary drainages and ground waters Jf^iufacejpw. of this type of analysis is to
identify whether changes in water qfeaHty are to in»ws, particularly in sensitive areas
such as proposed mixing zones. Xajwund wajraxmtribujglns to gaining systems may be
especially difficult to assess smjpuie not be amenable to direct sampling
(i.e., ground water seeps ii^^bMtream water). The analysis can be further
complicated iniSiistoric mining areas locatll||iSii6untainous terrain where contaminated seepage
flows through shaUow soils in response to seasonal climatic changes or short-lived storm events.
In cases such^^kese, the use-of djfe^salt tracers may provide a clearer understanding of
ground waterIkjdbnfcBtions to streacn^^^iarge (e.g., Kimball, 1997). Accurate discharge
measurements are important for compiling metal loadings (Section 4.3).
to Total Recoverable Constituent Concentrations
4.2 Translators for
•&«
Applicants and regulatory personnel may encounter the need to express water quality data
iplboth dissolved and/total recoverable (dissolved plus particulate) forms for NPDES permits and
TotaI|Maximum Daily Load (TMDL) allocations. NPDES regulations typically require permits
to'.'.fist metals limits in total recoverable form (there are exceptions, so applicants should check
with State and Federal agency personnel). On the other hand, EPA may be required to perform
TMDL calculations in which metals are expressed in dissolved form to ascertain that water
quality standards are being met. Accepted methods for translating between dissolved and total
recoverable forms are described in U.S. EPA (1996J).
43 Computing Metal Loadings
B-20
-------
Constituent concentrations, which are subject to dilution in downstream surface water
flows, provide limited information about the behavior of metals in streams. EPA (1996a)
suggests that this shortcoming can be overcome by considering metals loads, in which the
instantaneous load equals concentration multiplied by discharge:
L = C*Q
where L is the instantaneous load, C is metal concentration, and Q is stream discharje. The
constituent load downstream of a tributary inflow (LD) is equal the sum%he,a|itreani loads
(Ly) and contributing tributary (LT) loads:
D U T
(EPA, 1996a). An increase or decrease in load reflects!
constituent being transported per unit time. Increases
sources of contamination that may be recognized (i.e., tril
ground water inflow) during conventional sampling.
constituent is being removed by one or more physical,lhemi
Physical processes such as sedimentation and sedjj
adsorption and colloidal precipitation, and bic
in metals loads.
or decrease"ii|||pB&ss of the
ng a stream reacirSarf point to
gw) or unrecognized (i.e.,
gases in load suggest that a
ical processes.
processes such as
•take can cause changes
4.4 Other Characterization and Data Anal
jjjjijijf p
This section briefly descri^fessuesj
summaries of water quality dataiJSid when«i
Issue
• xs&t*
: applicajis should be aware of when preparing
. interpreting historical water quality.
4.4.1
etectic
lues
-•^m
Wai
H,stically contain analyses in which some constituent
at the method detection limit (MDL). Non-detected
3ns of summary data and can result in statistically
Uprated into summary data presentations. The latter occurs
Ration values are computed using assumed values (e.g., zero or
concentrations
values conn:
umuppojpt biases
whenever mean and
If MDL) for as below the detection limit. Further statistical challenges
;sented by water jjpality data sets that include multiple detection limit values.
Computatigjipf methods have been developed to deal with data sets containing below
values (Gilliom and Helsel, 1986; Helsel and Cohn, 1988; Helsel, 1990;
If 1990). In general, these approaches assume that constituent values have a
iflog-normal distribution. Based on this assumption, portions of the distribution
reported with BDL values can be reconstructed using either regression order statistics (Gilliom
and Helsel, 1986), probability plotting methods (Helsel and Cohn, 1988; Travis and Land, 1990),
or maximum likelihood estimations (Cohen, 1959). Extrapolated values are then used to
compute mean and standard deviation values for the constituent populations (Helsel and Cohn,
1988; Helsel, 1990). Appendix B of Helsel and Cohn (1988) describes a probability plotting
nor
B-21
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Mining Source Book
Appendix B - Receiving Waters
method to extrapolate data sets that include multiple detection limits. The method has gained
widespread acceptance for analyzing data with BDL values (e.g., Runnells et al., 1998).
The success with which a substitution method accurately determines the true statistical
parameters of a population depends on how closely the data fit an assumed distribution (Helsel,
1990). Bias and imprecision can be introduced whenever data depart from the assumed
distribution or when data are transformed (e.g., when means and standard deviations are
computed for log-transformed data and then converted back to original units) (Heisel, 1990).
Helsel and Cohn (1988) and Helsel (1990) compared root mean square Jpprs jlkhe statistical
parameters computed using six methods, including simple
half MDL). They concluded that a robust probability
to data above the reporting limit is used to extrapolate below
assessment of population mean and standard deviation.lpelsel
that percentile values are best estimated using maximuSfcelih estimaon
1
Software to compute summary statistical parame
using Helsel's method is available on the worldwide
Simple substitution for non-detected val
summary data that are prepared in this manm
limit are used for non-detected values.
reported as below the detection limit, or
prefers that applicants use techniques
4.4.2 Using Existing and Historical Dat
Watervquality data,ipayj|tist in p
'^^ ^, s' i^''^'"''''^!'^1''"'*
Inmany^caseSjithese J— —-^
to historical ;laiaidisturb
'•"t"f~; ' e',*f' '
the term
the data user
determine
values (e.g., one-
distribution fit
the bi
that include BDL values
.diac.com/~dhelsel/.
d and EPA accepts
f>f one-half the detection
+
>us parameters are
is not detected, EPA
.able detection limits.
IllJp^unpublished sources for some mining sites.
' ight into water quality prior to, and subsequent
s, including historical mining operations. The Agency uses
obtained from other sources. Before using such data,
>ility or quality of the data. It is often difficult to
because original laboratory reports are not included in
published^ documents^l|ffi;itaalyses were conducted prior to the acceptance of standard
laboratory protocols (se^^||feiix C, Characterization of Ore, Waste Rock, and Tailings).
Interpretations of receiving water quality that are based entirely or partly on existing data should
be made cautiously when one or more of the following parameters is unknown: exact sample
location, sample collection method, surface or ground water flow, sample preservation, sample
handling (chain-of-custody), analytical method, analytical detection limit, and lab accuracy and
precision^. -,,;:r.^::<'
It is important for applicants to recognize that secondary data may not have been
collected pursuant to a Quality Assurance Project Plan (QAPP), which often leads to problems
with its use. In general, applicants should assume that the use of historical or existing data sets,
in the absence of a QAPP or other supporting QA/QC documentation, is unlikely to be adequate
to support permitting and decision-making on a mining proposal. More detail on quality
assurance issues is provided in Section 5.0 of this appendix.
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Mining Source Book
dix B - Receiving Wate
4.5 Geochemical Modeling
The extent to which receiving waters disperse contaminants through the environment
depends partly on water chemistry and soil character (Hutchinson and Ellison, 1991). Under
equilibrium conditions, surface and ground waters will acquire constituent concentrations that
depend on local physical and chemical conditions, the rate at which secondary phases precipitate
from solution, and the tendency for dissolved constituents to sorb onto particle surfaces
(Schnoor, 1996). Figure B-l shows a conceptual physicochemical model of metapansport in a
surface water system illustrating the complex interactions affecting concehtratipn! In general,
waters with comparatively low pH can retain higher concentrations of metals in solution than
neutral waters (Salomons, 1995). Consequently, downstream changes ntpH, redox potential, QS,
other chemical parameters (e.g., in mixing zones) can lead to dissolution orprecipitation of j|
metal-bearing phases or their adsorption or desorption from bottom sediments or from colloidal
precipitates (Oscarson, 1980; Moore et al., 1988; Langmuk, 1997). Dissolved metels
concentrations also may change through adsorption ontfjgjd^irption from the surfaces of soil
particles, especially clays (Hutchinson and Ellison, 1995). The adsorptive
behavior of metals in water commonly varies nonlineajlf
of precipitation and complexation reactions (Salomonlf 1
anion exchange capacities (which measure of theji^^fctof adsor
function of the amount and type of clay and oj
Due to changes in soil character across a
vary.
Geochemical models can
under equilibrium conditions,
from co-existing solid phases
These pro are partic;
the more cc
MINTEQA.
due to pH control
different cation and
Can occur) that are a
!and Ellison, 1991).
soils also is likely to
to
ine the stability of phases in aqueous solutions
^ Vhetblimetals ate likely to be adsorbed onto or desorbed
um composition of natural waters.
iful how changes in pH can affect metals
• • i f i f
s are l^p^precipitate, be adsorbed, or remain as
water quality in mixing zones. Brief descriptions of two of
ivided below.
TEQA2
dil
1991) is an equilibrium geochemical speciation model for
ueous systems. fretm be used to compute the mass distributions between dissolved,
, and solid phz&es under a variety of conditions. The software includes an interactive
(PRODEFA2)to create input files. MINTEQA2 can be obtained from EPA's Center for
re AssessmeB/Modeling, ftp://ftp.epa.gov/epa_ceam/wwwhtml/minteq.htm.
Ibed
PHREEQC (Parkhurst, 1995) is designed to perform a variety of aqueous geochemical
calculations based on an ion-association aqueous model. The software can be used for calculations
of speciation, saturation index, reaction path, and advective transport and to conduct inverse
modeling. PHREEQC is available from the EPA Robert S Kerr Environmental Research Lab,
B-23
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Mining Source Book
Appendix B - Receiving Waters
Center for Subsurface Modeling Support, http://www.epa.gov/cgi-
bin/mdb_sw.cgi?modelkey=9009.
4.6 Fate and Transport Modeling
Numerical chemical fate and transport models are useful for analyzing spatial changes in
water quality parameters in receiving waters. In general, fate and transport models^mploy finite-
difference or finite-element techniques to route hydrographs and pollui
or ground water systems. These simulations couple equilibrium che
physical transport equations to calculate downstream or dow|^gradiea|
concentrations. These models are especially useful for eva|iping the"
pollutants from point and non-point sources through a wjjifshed. F
studies can be used to evaluate and model potential opejjf ional reU^ases in c<
NPDES permit application. Brief descriptions of somjpttiem^commonly are
provided below.
throuh' surface water
on models with
in constituent
sport of
lions, suckr
Enhanced Stream Water Quality Model with Uncertal
QUAL2EU is a chemical fate and trans
branching streams and well-mixed lakes.
quality planning tool, can be operated in
is available on the world wide web Ihro
L2EU)
One-dimensional Transport
OTISJs an equilih
been appMedjto small st
insport
sources
Hydrologic
llutants in
be used as a water
ic mode. The software
•e Assessment Modeling
by
the U.S. Geological Survey that has.
bloradopre been contaminated by mine drainage
lows users to subtract the effects of one or more input
'RAN(HSPF)
HSPF simulates|i^^i|gic and water quality processes on pervious and impervious land
surfaces, in the soil profife^Sad in streams and well-mixed impoundments. The operational
connection between the;Mnd surface and the instream simulation modules is accomplished
through a network bloeK of elements. Time series of runoff, sediment, and pollutant loadings
generated on the land Surface are passed to the receiving stream for subsequent transport and
transformation simulation. Water quality and quantity can be evaluated at different segments or
outflow points within a watershed. Given appropriate input data and constraints, the model can
account for degradation (i.e., decay) or retardation of pollutants. HSPF is available on the world
wide web through EPA's Center for Exposure Assessment Modeling,
ftp://ftp.epa.gov/epa_cearn/wwwhtml/softwdos.htm.
B-24
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Mining Source Book
dixB-Re
• Wi
Finite Element Model Water (FEMWATER)/Finite Element Model Waste (FEMWASTE)
FEMWATER is a numerical ground water model that uses a finite-element solution to
solve the governing equations for ground water flow. It can be used to create two-dimensional
area! or vertical models as well as three-dimensional models in both saturated and unsaturated
media. Because of its numerical approach, it can be used to model transient flow or steady-state
flow under anisotropic and layered aquifer conditions. FEMWASTE is a two-dimensional
transient model for the transport of dissolved constituents through porous media./* Modeled
transport mechanisms include convection, hydrodynamie dispersion, chemical sorption, and
first-order decay. The waste transport model is compatible 4with the water flow model
(FEMWATER) for predicting connective Darcy velocities in partially saturated porous media. ^
Outputs from ground water fate and transport modeling can be used to devtelop*pollutant input'*
parameters for point or non-point sources to surface water fate and transport raodels'such as
QUAL2EU or HSPF. FEMWATER is available on the world wide web through EPA's Center
for Exposure Assessment Modeling (ftp://f^.epa.gov/epajc^ii/wwwhtml/sofhvdos.htm).
4.7 Other Analysis Techniques
Plots of water quality data can reveal pot
concentrations and mass loading that occur <
that occur with seasonal changes in dische
trend). Mass loading profiles (constituej
for identifying reaches of a stream in ijjlicn me
reaches affected by contaminant wjjpWf(for i
(Walton-Day, 1998). Mass lo;
Survey to identify and rank
mine landsJiylie Ark
that
suspended;
't*
Alt
gnificant changes "in constituent
iugh a watershed (spatial trend) or
"within a watershed (temporal
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Mining Source Book
Appendix B - Receiving Waters
5.1 Overview of the Process for Developing a Monitoring Plan
The Agency QA Division recommends the use of a systematic planning process when
developing a monitoring program. One such systematic process is the Data Quality Objective
Process (U.S. EPA, 1994e). MacDonald et al. (1991) and Dissmeyer (1994) also provide
examples of systematic planning approaches that may be applicable to mining projects. Figure
B-2, taken from Dissmeyer (1994), is an example of the process used to develop a program to
monitor receiving water quality. The two steps most critical to developing a sound plan are to
identify specific monitoring goals and objectives and to determine whether the'plan, when
implemented, meets those objectives. For example, one objective of a surface water monitoring
plan might be to define temporal differences in water quajijjftfeat resurt fr®m general changes ir
<'•''}': • &," '
seasonal flow (see Section 3.0).
Monitoring plans will vary depending on the p^icular
they include goals and objectives; sampling locations aict',
parameters that will be monitored and their required dete'
stream morphology at surface water sampling points; s>
procedures; sample transport and chain-of-custody procedures;
protocols; and data analysis and reporting proo
The time period from mine planni:
monitoring typically is measured in decajPI. D
operations, monitoring requirements, apf sampluff and
Therefore, establishing comprehen^e|iualityj^urance
toring situaticte. l^|eneral,
; a list of water quality
s; a brief description of
handling, and analysis
prance/quality control
2Cl
wa
will help to minimize the impac1|Biese cj^fftges by ej
approach is used to collect and
through a wpitten plan wil
short- andlonj-term •
Al
and control, tK
Sampling and
and QAPf can be
defensible sampling
ition and post-operational
mmental conditions, mine
s^protocols are likely to change.
ll quality control (QA/QC) protocols
that a consistent and accurate
ita. Implementing these protocols
;d data can be used to evaluate both the
ensuring long-term data quality assurance
approach is the development of a either a
Assurance Project Plan (QAPP), or both. The SAP
one document, the purpose of which is to establish sound and
protocols that can be used to generate unbiased data with
known and traceable accofacyxand precision. For the purposes of this appendix, the combined
QA/QC document is referred to as the QAPP. The QAPP should be prepared in a manner that
promotes acceptance and use by field and laboratory personnel. It should serve as a resource tool
and reference manual for all sampling and analytical procedures. The QAPP should be modified
when changes occur that significantly alter the applicability or effectiveness of the document.
5.2 Components of a QAPP
The primary elements of an acceptable QAPP include comprehensive discussions
regarding Project Management, Measurement and Data Acquisition, Assessment and Oversight,
and Data Validation and Usability. Each of these are described in the ensuing subsections. A
complete explanation of and prescribed format for all required elements is presented in U.S. EPA
B-26
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Mining Source Book
Appendix B - Receiving Waters
(1998c; 1998d). Both documents are available on the world wide web
(http://www.epa.gov/rlOearth/ofFices/oea/qaindex.htm). Although monitoring programs initially
are developed to support decision-making and permitting of proposed mining projects, the formal
monitoring programs that are documented in a QAPP can be later used or amended to support
other objectives during various stages of a mine life cycle, including operation, closure and post-
closure. For example, NPDES permits generally include specific requirements for the
preparation of QAPPs to guide collection of water quality data during mine operation. Typically
NPDES permits specify that QAPPs adhere to the two guidance documents cited above.
B-27
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Mining Source Book
Appendix B - Receiving Waters
Define personnel and budgetary constraints
Define monitoring parameters.
sampling frequency, sampling
location, and analytic procedures
Evaluate hypothetical
or, if available, real data
Will the data meet the
proposed monitoring objectives?
Yes
No
Is the proposed monitoring
program compatible with
available resources?
Yes
No
Initiate monitoring activities on a pilot basis
Analyze and evaluate data
Does the pilot project meet
the monitoring objectives?
Yes
No
Continue monitoring and data analysis
Reports and recommendations
Revise the
objectives
or the
monitoring
procedures
Revise
monitoring
plan as
needed
Figure B-2." Example flow-chart for developing a monitoring project (from Dissmeyer, 1994).
B-28
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Mining Source Book
idixB-Re
! Waters
5.2.1 Project Management
The project management portion of the QAPP includes an introduction and sections that
describe the project schedule, training and certification, expected data quality, and data quality
objectives.
Introduction
*%
>t^ -,
>
The introduction should be informative and provide the foundation for solid QA/QC
procedures. The section should address plan approval, modification, distribution, and project
organization. The introduction should establish procedures for plan modification and identify by
name the individuals responsible for project management, overall project quaMty assurance, field
work, and laboratory quality assurance. This should be followed by a detailed presentation of
project background information and a brief problem statement. Maps and/or figures should be
provided where appropriate.
Project Schedule
An overall project schedule should be devetepeSthat highlights key project dates, if
applicable. The schedule should be developed i^aa^asity readable format and all project-
associated staff should be aware of its presjpe, contej^sitHikey dates.
'H •* A v
Training and Certification
The QAPP should addres
of certifications held by the lat
the relevanWiertifications,
• sampling and safijiy training and should include a listing
lory. If a commercial laboratory is contracted, it should hold
fanned aliawsesiifem the state where the project is located.
Expectet
; to
icertainty associated with a particular data value (i.e.,
ata point is what the analysis has determined it to be?).
lents of the sampling event, from the sampling design through
I. Early in the QAPP development process, the acceptable
Dataql
how sure ar&
Data qua^fis affect!
the laboratory analysis 1^
andjjipropriate levels must be determined through the use of a systematic
process. Sudjlecisions will depend on the contaminant of concern, the effect it has on
and environmjjfel health, and the levels at which concerns arise.
w
Igarding acceptable levels of uncertainty should consider the following
What chemical(s) are expected to be found at the site?
Approximately what level of contamination is expected (high = >10 ppm; medium =
10 ppm to 10 ppb; low = <10 ppb)?
B-29
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Mining Source Book
Appendix B - Receiving Waters
What is the action level or level of concern for the contaminant for human health?
For the environment?
Based on the answers to questions 1 through 3, which analytical methods are
appropriate to achieve needed detection limits?
How was the sampling design developed (e.g., area vs. number of samples; frequency
of sampling; random or biased sampling)? . /J1
How many of the samples will be field quality control samples (ire/, field duplicates,
field blanks, equipment blanks, trip blanks, fielfi|pikes or split samples)? M
My «^..nik Jr
How many samples will be laboratory qualitf||control saioples?
Data Quality Objectives and Data Quality Indicators
After a decision has been made regarding the expected
address data quality objectives and measuremf
quantitative and qualitative objectives that defiH
project. Data Quality Indicators (DQIs) are^specific|
project, such as sample measurement prejlsion, ac?
for me
, the QAPP should
ives (DQOs) are
fthe requirements of the
of data needed for the
tiveness, comparability, and
completeness. DQOs and DQIs definejfie qualitylof the s^^Rrequired from the laboratory
, f(\ <*'£'-,"•'
and are used in any quality assuran^niMews of the field Jild laboratory data. Review of the
quality control data against the 'and DQIs determjps if the data are fully usable,
unusable.
considered estimates, or reject
Precision is the
[RPD]). his iiidiGater relate:
Accuracy'isthedeisee of
. *= >^,w - ~ "' ~ •-&; " *~
.utual agjjJemerit between or among independent
.dard deviation [SD] or relative percent difference
.lysis of duplicate laboratory or field samples.
.ent of a measurement with a known or true value. To
determin®;accuracy, a IdKKatory or field calibration value is compared to the known or true
\
concentration. The laboratory, by developing a database of instrument runs using performance
samples, should be able provide information regarding this objective.
^
tSt
Completeness, compares the data actually obtained to the amount that was expected to
have been obtainecLJDue to a variety of circumstances, analyses may not be completed for all
samples. The percentage of completed analyses required will depend on the sampling design and
data use. Expectations of completeness should be higher when fewer samples are taken per event
or site.
Representativeness expresses the degree to which data accurately and precisely represent
a characteristic of an environmental condition or a population. It relates both to the area of
interest and to the method of taking the individual sample. The idea of representativeness should
be incorporated into discussions of sampling design.
B-30
-------
Comparability expresses the confidence with which one data set can be compared to
another. The use of standard, published methods allows straightforward comparisons of data
collected during multiple sampling events.
Data quality indicators for field and laboratory measurements should be stated in
measurement performance criteria. Field measurements should be made with calibrated
instruments; laboratory measurements should be specified by individual method criteria or by
laboratory control limits. -K
5.2.2 Measurement and Data Acquisition
The measurement and data acquisition section dejpribes in detal^|p»here, and when**
data will be collected and analyzed and provides supposing quali^eontrol intenation related to
sample handling; equipment calibration, testing, and r^^^anaj^cal methods and quality
control requirements; and data management. This applicable^ all field
personnel insofar as it establishes required procedures and field
measurements. Where possible, information should
understandable formats and should clearly identify pi
strongly encouraged. Tables should be created
(e.g., station 102), common name (e.g., Dry
effectiveness of treatment), and sample type^^e.g.,
provide the reason for including specificjpmple sij
of the sample location. Sampling andj
recommended in cases where mult
Critical and Non-Critical Sami
or other easily
te sample^l^^lSsigned identifier
"'"l.r:'.-1^.^"^ ' -^/
mill), intertl«»spurpose (e.g., assess
igjfjK etc.). The QAPP should
essary, detailed descriptions
mild be included; tables are
on varied schedules.
es ve
aplestnaybe determined to be less critical than others (e.g.,
ice samples). The collection of critical samples may be
ion-critical samples may be postponed or excluded
Criteria for such should be clearly identified.
informal
required atH
based on weat
Sample
'Field sampling procedures should be completely described at a level
rauld permit a nejjlmployee to read and implement these activities without jeopardizing
uality of data. TjIrQAPP should specify methods for collecting different types of samples,
leld equipir^pf and preparing, preserving, and handling samples. In addition, it should
[regarding approved sample containers, preservation methods, holding times,
tethods. Proper chain of custody procedures and an example of the form to be
Pbe provided. The citation and attachment of Standard Operating Procedures to the
QA plan can reduce the amount of writing that must be done to properly document the details for
a project. For guidance on the preparation of Standard Operating Procedures, refer to U.S. EPA
(1995). Field staff should be thoroughly trained on all elements of field sampling and
measurement and one or more trial events should be conducted prior to initiating unsupervised
sampling.
use
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Mining Source Book
Appendix B - Receiving Waters
Analytical Methods and Quality Control Requirements
The QAPP should specify laboratory analytical methods and quality control procedures.
A preferred approach is to include a table that presents the analytical methods, method detection
limits (MDLs), reporting limits or minimum levels, laboratory precision (in relative percent
difference (RPD)) and accuracy (in % recovery), sample holding times, sample container type,
sample preservation method, and completeness requirements. The table provides ayreference for
field teams and allows for easy review of the data deliverables package grovided^ the
laboratory. EPA has established preferred analytical methods for siirfa^pter^ound water,
soils, sediment, and other media (EPA, 1983;! 986; 1996b-i); other
APHA et al. (1992) and ASTM (1996) (see Appendix C, Characterize
and Tailings). Method detection limits are specified in the indivi
limits or minimum levels are based either upon desiredj&ta accuraey/and/o:
requirements (e.g., NPDES permit limits). Although p^fekm^ftf accuracy
vary depending on the specific analysis and/or sample to <30% RPD
recovery are commonly applied values for water samples^
described in
', Waste Rock,, ;w,
reportir
ically
to 115%
In addition, the QAPP should specify sample preparatio
procedures as described in the laboratory's QA/Qp^^p[al or p
manual should be included with the QAPP perti
extracted and included in the text of the Q
Field Quality Control
Quality control checks ofjpi3'samp.
used to assess and document daillq'uality,
,^ $•?.'••
process. Field blanks, equjqpjeat deconta
blanks, and standard reference samples c
collection and handling pi
.and sampling handling
QA/QCplanor
brmation should be
; procedujps and laboratory analyses should be
idenjjif discrepancies in the measurement
s, field duplicates (or replicates), trip
' to assess sample representativeness, sample
eld equipment decontamination procedures, and laboratory
les, which are used to evaluate whether contaminants
the sampling process, are created by pouring deionized
precision and accuracy. Fiel
have been introduced into the
water through a field fiUer into a sampling container at the sampling point; the field blanks are
analyzed for metals and other constituents. In some cases, trip blanks may be needed to evaluate
whether shipping and handling procedures introduce contaminants into the samples, or if cross-
contamination (e.g., migration of volatile organic compounds) has occurred between the
collected samples. Duplicate samples, which are collected simultaneously with a standard
sample from the same&ource under identical conditions and placed into separate sample
containers, should be used to assess laboratory performance. One or more duplicate samples
should be collected and analyzed for every 20 samples (5%) or once per sampling event,
whichever is more frequent. The duplicates should be labeled in a way that does not reveal their
status to the laboratory.
Laboratory Quality Control
Laboratories routinely monitor the precision and accuracy of their results through analysis
of laboratory quality control samples (EPA Region 10 provides a document for laboratories
B-32
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Mining Source Book
idix B - R<
• Wa
entitled "Guidance on Preparation of Laboratory Quality Assurance Plans," available on the
world wide web at http://www.epa.gov/rlOearth/offices/oea/qaindex.htm). The QAPP should
provide a reference to the specific QC protocols used by the labs that will conduct analyses. The
typical frequency specified for laboratory QC samples (e.g., matrix spikes, matrix spike
duplicates, method blanks, lab control samples) is one of each QC sample that is appropriate for
the method per batch of samples. A batch of samples is defined as 20 or fewer samples that are
received by a laboratory within a 14 day period for the specific project. If deemed necessary for
the project, a higher frequency of QC samples can be designated.
Corrective Action
If nonconformance with any QAPP element is id^lified, correcttv^ctioii ^iould be .*
taken to remedy, minimize, or eliminate the nonconforapnce. Sampling andi^^i^iir^mien|*
system failures include an inability to collect a sample JlinDle
measurement errors, and laboratory errors. The QAPP^^ffl^escribe remedies^each of
these possible system failures.
Calibration
Field equipment should be calibrated:
calibration log. The QAPP should includejjjfefof i
meters, DO meters, etc.) and appropriatejpilibratiqi
Data Management
Data management
should inck*|e acceptabl
a
shd
o
measures that
data sheets;
system,
be kept in a field
calibration (e.g., pH
shed for field and laboratory data. They
s, laboratory data deliverables, data
f electronic data management, and records
a list of the steps that will be taken to ensure that data are
.analysis to reporting. Discussions should focus on the
ita collection processes, including field notes or field
laboratory reports; and to review the data entry
--'•y&
lab
%wfz
Chain-of-cjKP&y records are used to document sample collection and shipment to
lysis. All sample shipments for analyses must be accompanied by a
^record. Form(s) should be completed and sent with the samples for each
each shipment (i.e., each day).
5.2.3 Assessment and Oversight
The QAPP should adequately describe all monitoring program assessment and oversight.
Oversight evaluates how well the specifications contained within the QAPP are being
B-33
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Mining Source Book
Appendix B - Receiving Waters
implemented and the types of information needed to continuously improve the monitoring
program. It also verifies that the quality assurance guidelines for sampling and analysis are being
met. The QAPP should identify the individual(s) responsible for ensuring that sampling and QA
activities are being implemented as described in the QAPP. The primary elements of an
acceptable assessment and oversight program include audits of field data and sample acquisition,
laboratory audits, and audits of data management.
ram^
•>*
Audits of Field Data and Sample Acquisition
Data quality audits assess the effectiveness and docujjpitationf
data collection processes. In particular, these audits evalualiSvhether
Jl A J £4«9--,----
the project are being met. Additionally, they determine Jpether the
the current project. The frequency of these audits, whi
-------
Mining Source Book
dixB-Rc
' W
Reconciliation with DQOs andDQIs
The QAPP should clearly identify the actions that will be taken to reconcile any
deviations from the DQOs and DQIs. Resolution should be made by identifying the elements of
the sampling and data collection process that are in question and addressing the situation that
caused the qualification.
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Mining Source Book
Appendix B - Receiving Waters
6.0 REFERENCES
Allison, J.D., Brown, D.S., and Novo-Gradac, K.J., 1991. MINTEQA2/PRODEFA2, A
Geochemical Assessment Model for Environmental Systems: Version 3.0 User's Manual,
U.S. Environmental Protection Agency Report EPA/600/3-91/021.
American Public Health Association, American Water Works Association, and Water
Environment Federation (APHA et al.), 1992. Standard Method? for the^dmination of
Waters and Waste-waters, 18th edition, American Public Health J|||pcigpb, Washington,
its
D.C..
ASTM, 1996. Annual Book of ASTMStandards, AmerieajixSociety
Philadelphia, PA.
Boult, S., Collins, D.N., White, K.N., and Curtis, Transport
Polluted by Acid Mine Drainage—The Afon UK, Environmental
Pollution, vol. 84, pp. 279-284.
Bowers, T.S. and Nicholson, A.D., 1996. Distin
Background Levels of Metals, Geologj
vol. 28, p. A-465.
Buxton, H.T., Nimick, D.A., von Gue
Watershed Strategy to
Proceedings of the
May 30 - June 6-4
** - ^i&a&ML'^. *i-S
Canter, L.W,l98§«rver
pp..
from Natural
with Programs,
r, A.G., Gray, J.R., Lipin,
B.R., Marsh, S.P., WoodwaaPfXF., Kjpball, B.AjlFinger, S.E., Ischinger, L.S.,
Fordham, J.C., Power, N^pBunck^JKf. and Jjles, J.W., 1997. A Science-Based,
Rem^ation of Abandoned Mine Lands,
zrence on Acid Rock Drainage (ICARD),
"Columbia.
iort Efft
%g?f>'?;
Intern'^"
LCOUVl
to'Monitoring, Lewis Publishers, Inc., Chelsea, MI, 170
Chapman, B.M., Jones,'Mp*and Jung, R.F., 1983. Processes Controlling Metal Ion Attenuation
A in Acid Mine Dra^^e:$^-eams, Geochimica Cosmochimica etActa, vol. 47, pp. 1957-
^ 1973. if'""
Church, S.E., Kimball, ^.A., Fey, D.L., Ferderer, D.A., Yager, T.J., and Vaughn, R.B., 1997.
Source, Transport, and Partitioning of Metals Between Water, Colloids, and Bed
"~\..•* Sediments of the Animas River, Colorado, U.S. Geological Survey Open-File Report 97-
151,135"pp.
Church, S.E., Fey, D.L., and Brouwers, E.M., 1998. Determination of Pre-Mining Background
Using Sediment Cores from Old Terraces in the Upper Animas River Watershed,
Colorado. In: Nimick, D.A. and von Guerard, P., eds., Science for Watershed Decisions
on Abandoned Mine Lands: Review of Preliminary Results, Denver, Colorado, February
4-5, 1998, U.S. Geological Survey Open-File Report 98-297, p. 40.
B-36
-------
Mining Source Book
Appendix B - Receiving Waters
Coeur Alaska, Inc., 1997. Amended Plan of Operations for the Kensington Gold Project August
1997.
Cohen, A.C., Jr., 1959. Simplified Estimators for the Normal Distribution when Samples are
Singly Censored or Truncated, Technometrics, vol. 1, no. 3, pp. 217-237.
Dames & Moore, 1983. Environmental Baseline Studies, Red Dog Project. Report prepared for
Cominco Alaska, Inc. as cited in EVS Environment Consultants, Environmental
Information Document, NPDES Permit Reissuance Request Jbrjijffptajmnual Discharge
of 2.9 Billion Gallons, Cominco Alaska Red Dog Mine, J^/wme|lf^%ctober 1997.
Dissmeyer, G.E., 1994. Evaluating the Effectiveness of Forestry Bestii&agementfractice&m
Meeting Water Quality Goals or Standards, U.^Depza^mea^^of Agriculture* Forest ^
Service, Miscellaneous Publication 1520. VT' jfx *<**'..
Gilliom, R.J. and Helsel, D.R, 1986. Estimation of Distribull^tta^Parameters for Censored Trace
Level Water Quality Data, 1, Estimation Teclm<$es^Wat$r 'Resources Research, vol. 22,
no. 2, pp. 135-146.
Hamilton, C.E., ed., 1978. Manual on Water,
American Society for Testing and
Helsel, D.R., and Cohn, T.A.
WatfeQualiry Dai
Hughes:
. Us<
Technrlpublication 442A,
472 pp.
Helsel, D.R., 1990. Less than Obviou^tatisticajFTreataH^BData Below the Detection Limit,
Environmental Science andffwnolofvl. 24, Jj 12, pp. 1766-1774.
*•
iptive Statistics for Multiply Censored
vol. 24, no. 12, pp. 1997-2004.
ed Characteristics to Select Control Streams for Estimating
« Extensively Disturbed Streams, Environmental
-262.
0.^1991. Mine Waste Management, California Mining
of Tracer Injections and Synoptic Sampling to Measure Metal
Loading fromMid Mine Drainage, U.S. Geological Survey Fact Sheet FS-245-96,4 pp.
Aqueous Environmental Geochemistry, Prentice-Hall, Englewood Cliffs,
Knorre, H. and Griffiths, A., 1985. Cyanide Detoxification with Hydrogen Peroxide Using the
Degussa Process. In: Van Zyl, D. (ed.), Cyanide and the Environment, Proceedings of a
Conference, Tucson, Arizona, December 11-14, 1984, Geotechnical Engineering
Program, Colorado State University, Fort Collins, Colorado, pp. 519-530.
B-37
-------
Mining Source Book
Appendix B - Receiving Waters
MacDonald, L.H., Smart, A.W., and Wissmar, R.C., 1991. Monitoring Guidelines to Evaluate
Effects of Forestry Activities on Streams in the Pacific Northwest and Alaska, U.S.
Environmental Protection Agency Report EPA 910/9-91-001.
Mast, M.A., Wright, W.G., and Leib, K.J., 1998. Comparison of Surface-Water Chemistry in
Undisturbed and Mining-Impacted Areas of the Cement Creek Watershed, Colorado,
Science for Watershed Decisions on Abandoned Mine Lands: Review of Preliminary
Results, Denver, Colorado, February 4-5, 1998, U.S. Geological SurveyJ^fen-File
Report 98-297, p. 38.
j4Sf»
Montgomery Watson, 1996. Treatment Alternatives for
Wohlgemuth (Montgomery Watson) to Rick Ricjuifs (Coeur AjltS!
12 pp. Attachment 5 to Coeur Alaska, Inc., KenMgton Gold Frojo
Information, National Pollutant Discharge Elirr^^on System (NPDE!
Technical Support, September 1996.
Moore, J.N. and Luoma, S.N., 1990. Hazardous Wa
Case Study, Environmental Science and Tec}
Moore, J.N., Ficklin, W.H., and Johns, C.,
Sulfidic Conditions, Environmental
Nordstrom, D.K., Alpers,
Pre^Mining and B
Society ofAmert
.dum from G,
y 12, 196,
and
e Metal Extraction: A
pp. 1278-1285.
!'•
'and Metals in Reducing
ol. 22, no. 4, pp. 432-437.
Nielson, D.M., ed., 1991. Practical Hmfdbook o/Grour
Inc., Chelsea, MI, 717 pp.v1
^Monitoring, Lewis Publishers,
Geochemical Methods for Estimating
ns in Mineralized Areas, Geological
s, vol. 28, p. A-465.
Oscarson, D.W^ &apg, PMijjp&tJ&pi
-------
Mining Source Book
idixB-Rc
Qi, S.L. and Sieverling, J.B., 1997. Using ARC/INFO to Facilitate Numerical Modeling of
Ground-Water Flow, Proceedings of the Sixteenth Annual Environmental Systems
Research Institute, Inc. (ESRI) User's Conference, July 7-11,1997, San Diego, CA.
Runkel, R.L., Bencala, K.E., Broshears, R.E., and Chapra, S.C., 1996. Reactive Solute Transport
in Streams—1. Development of an Equilibrium-Based Model, Water Resources
Research, vol. 32, no. 2, pp. 409-418.
jp|Sp'
Runnells, D.D., Shepherd, T.A., and Angino, E.E., 1992. Metals in Wal|r, Determining Natural
Background Concentrations in Mineralized Area, E-onmeS^^ce and
Technology, vol. 26, pp. 2316-2323.
Runnells, D.D., Dupon, D.P., Jones, R.L., and Cline, Dj| 1998.
Background Concentrations of Dissolved Com^^nts inl^ater at Miri
Smelting Sites, Mining Engineering, vol. 50,
fand
Salomons, W., 1995. Environmental Impact of Metals
Processes, Predictions, Prevention, Journal ofiSeocher,
23.
fining Activities:
ration, vol. 52, pp. 5-
Schemel, L.E., Kimball, B.A. and BencalaJ^, Forfation and Transport of
Aluminum and Iron in the Animjptiver Science for Watershed
Decisions on Abandoned MineMnds: RjjfjJZw Results, Denver, Colorado,
February 4-5, 1998, U.S. Opejfile Report 98-297, p. 17.
Schnoor, J.L., 1996. Environmfl Model
andAil, John Nex"
sfs^lee, G.S., and Ficklin, W.H., 1994. Predicting Water Contamination from
^^ "^ I Mines and Mining Wastes: Notes, Workshop No. 2, International Land
Reclamation and Mine Drainage Conference and Third International Conference on the
Abatement of Acidic Drainage, U.S. Geological Survey Open-File Report 94-264, 112 pp.
B-39
-------
Mining Source Book Appendix B - Receiving Waters
Stanley, C.R., 1987. PROBPLOT—A Computer Program to Fit Mixtures of Normal (or Log
Normal) Distributions with Maximum Likelihood Optimization Procedures, Association
of Exploration Geochemists Special Volume 14 .
Stumm, W. and Morgan, J.J., 1996. Aquatic Chemistry: Chemical Equilibria and Rates in
Natural Waters, 3rd edition, John Wiley & Sons, New York.
May 1993.
U.S, Environmental Protection Agency, 1994a. Technical Resource Document, Extraction and
Beneficiation of Ores and Minerals, Volume 1, Lead-Zinc, Office of Solid Waste, EPA
ias& 530-R-94-011, June 1994.
U.S. Environmental Protection Agency, 1994b. Technical Resource Document, Extraction and
Beneficiation of Ores and Minerals, Volume 2, Gold, EPA Report 530-R-94-013.
B-40
-------
Mining Source Book
dixB-Rc
• Wa
U.S. Environmental Protection Agency, 1994c. Technical Resource Document, Extraction and
Beneficiation of Ores and Minerals, Volume 4, Copper, EPA Report 530-R-94-031.
U.S. Environmental Protection Agency, 1994d. Water Quality Standards Handbook: Second
Edition, EPA 823-B94-005a, August 1994.
U.S. Environmental Protection Agency, 1994e. EPA QA/G-4 EPA Guidance for the Data
Quality Objective Process, EPA 600-R-96-055. Jfr
U.S. Environmental Protection Agency, 1995. EPA QA/G-6jjPA the Preparation
of Standard Operating Procedures for Quality-Rel&^^OperaJfoW^^i 600-R-96-007.
/-.:• &&,*' v,.™-Ua;f>>',:^*U>&^:, ,f: -_/:
U.S. Environmental Protection Agency, 1996a. U.S. EP-A NPDES Permit
EPA-833-B-96-003, December 1996. I'
U.S. Environmental Protection Agency (EPA), 1996b. Me^odl631: Mercury in Water by
Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence Spectrometry, Office
of Science and Technology, Report 821 /R-96-012.
•<*»
U.S. Environmental Protection Agency (EPtygSffScS Method 1632: ^Determination of
Inorganic Arsenic in Water by Hydjjjj^energiiw Flame Atomic Absorption, Office of
Science and Technology, Report fin /R-96-013".'' ^
U.S. Environmental Protection Ag^ff (EPA)^96d.
Hexavalent Chromium b
Report 821/R-96-003.
od 1636: Determination of
of Science and Technology,
I996e. Method 1637: Determination of Trace
Chelation Preconcentration with Graphite Furnace
ience and Technology, Report 821/R-96-004.
f
(EPA), 1996f. Method 1638: Determination of Trace
'ers by Inductively Coupled Plasma-Mass Spectrometry, Office
, Report 82 l/R-96-005.
ivironmental Fraction Agency (EPA), 1996g. Method 1639: Determination of Trace
Elements in Waters by Stabilized Temperature Graphite Furnace Atomic
,fAbsorption^Kfice of Science and Technology, Report 821/R-96-006.
pi
bntal Protection Agency (EPA), 1996h. Method 1640: Determination of Trace
dements in Ambient Waters by On-Line Chelation Preconcentration and Inductively
Coupled Plasma-Mass Spectrometry, Office of Science and Technology, Report 821/R-
96-007.
B-41
-------
Mining Source Book Appendix B - Receiving Waters
U.S. Environmental Protection Agency (EPA), 1996i. Method 1669: Sampling Ambient Water
for Trace Metals at EPA Water Quality Criteria Levels, Office of Science and
Technology, Report 821/R-96-011.
U.S. Environmental Protection Agency, 1996J. The Metals Translator: Guidance for
Calculating A Total Recoverable Permit Limit from a Dissolved Criterion, Office of
Water, EPA 823-B-96-007, June 1996. A
U.S. Environmental Protection Agency, 1997a. EPA's Hardrock Mining Framework, EPA-833-
B-97-003, September 1997. Jj^ * ., t ]
U.S. Environmental Protection Agency, 1997b. Establifg Site Spe^c^uatie Life Criteria
Equal to Natural Background, Memorandum frf|| Tudor Tt'-Davies^OfficeoJ^^^pe
and Technology to Water Management Divisio^^kecto^^Regions
Tribal Water Quality Management Program 5,1997^ppjr
U.S. Environmental Protection Agency, 1998a. Morenci Mine,
Draft Report prepared by Science Applications^fnternat^^^^H^jration, July 1998.
X^% "^^!^^^^^^&^^H?^\
U.S. Environmental Protection Agency, Quality Criteria,
Federal Register, December 10,
U.S. Environmental Protection Agenc|i^998c. Jpfcl Guidance for Quality
Assurance Project Plans, EPA 6004j*8-01 Jjf
U.S. Environmental Protection Agency, 199lpL R-5 EPA Requirements for Quality
Assurance Project PJanS, Draft
U.S. Geological Survey, 19^7 fictional Field Manual for the Collection of Water-Quality Data,
r-ReswKO^S Investigations, Book 9, April 1998.
Viessman, Wr, Jr. and Hammer, MJ^T993. Water Supply and Pollution Control, Fifth edition,
Harper Collins Cofege-Publishers, New York, 860 pp.
1 ••?"•'"•-yn* ,
^ *
Walton-Day, K., 1998. Geologic and Geochemical Characterization of Mined Lands,
Unpublished notes from a presentation to the South African Mining Delegation Seminar,
EPA, Denver, CO, August 24 to September 4,1998.
B-42
-------
CHARACTERIZAHON OF
ROCK, AND TAILINGS
-------
Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Table of Contents
1.0 GOALS AND PURPOSE OF THE APPENDIX
1
2.0
3.0
ANALYSIS OF PHYSICAL CHARACTERISTICS ............................. 1
2.1 Extent of Analysis [[[ 1
2.2 Physical Parameters ...................................... ^ ......... 2
2.3 Mineralogical Composition ........................ * ..... f?f ........... 3
ANALYSIS OF CHEMICAL COMPOSITION . . . . . ............ 4
3.1 Analysis of Solids
3.2 Analysis of Liquids ||f ^,7 .. .'.II
4.0 ANALYSIS OF CONTAMINANT MOBILITY!
4.1 Mineralogical Considerations
Physical Considerations
Acid Generation Potential
4.3.1 Static Tests
4.3.1.1
4.2
4.3
Acid-Base
4.3.1.1.1
4.3.1.1.2
Static Te
Inte
StatfflKeomm
4.3.1.2
4.3.1.3
4.3.1.4
Kinetic Te
4.3.2
OLIDS 8
8
8
9
10
10
enerating Potential ... 11
Neutralizing Potential .. 13
cator Value 14
15
16
16
17
4.4.2
4.4.2
and Modified Conventional Humidity
17
RKHumidity Cells 18
xhlet Extractions 18
Column Tests 19
Shake Flask Extractions 19
Field Tests 20
interpreting Kinetic Test Results 20
State Recommendations 21
Wiatical Models 22
Procedures 23
J.S. EPA Procedures 23
4.4.1.1 EP Toxicity Test 23
4.4.1.2 Toxicity Characteristic Leaching Procedure Test 23
4.4.1.3 Synthetic Precipitation Leaching Procedure Test 24
4.4.1.4 Monofilled Waste Extraction Procedure 24
State Procedures 24
4.4.2.1 State of Nevada Meteoric Water Mobility Procedure 24
-------
Mining Source Book Appendix C — Characterization of Ore, Waste Rock, and Tailings
TABLE OF CONTENTS
(continued)
4.4.3.1 British Columbia Procedures 25
4.4.3.2 U.S. Army Corps of Engineers Procedures 25
4.4.3.3 ASTM Procedures % 26
4.4.4 State Recommendations • ".". 26
4.4.5 Comparison of Leaching Procedures 26
,'•"'" * - * .f'" .4*
5.0 ANALYSIS OF FATE AND TRANSPORT vT;! >. :27
y '* * . i- ,''•',/
5.1 Developing a Conceptual Model ,v-*t
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
1.0 GOALS AND PURPOSE OF THE APPENDIX
EPA expects that applicants will conduct a sufficient number and variety of
environmental tests on a representative suite of samples in order to support projections of
wastewater and solid waste management practices and effluent quality. This appendix describes
the methods used to characterize the solid wastes from mining activities and the rationale for
their implementation. The materials in this appendix complement those in Appendix B,
Receiving Waters and Appendix F, Solid Waste Management.
.7 «&~'*^ . _&'.??
Determining the physical and chemical character of solid wasteaffit^als is a prerequisite
to delineating the area that would be affected by waste disp%|al; rec
chemical, and biological impacts of waste disposal; andjiveloping
measures. Environmental test samples should be collecfffl as part gf a com|
designed to examine the range of conditions that occ
mining has concluded or is on-going, tested materials
operations. For areas in which mining is proposed or p:
change, tested materials should include batch and pilo
chemical characterization studies should be conduct
estimates of the potential environmental impacts.,
ducts.
'uldccur. For
•reduced by normanine
.ods are expected to
Physical and
;ovides conservative
An environmental sampling pro
designed to represent the different lithol
excavated, processed, disposed of, or
chemical and physical variability
borrow materials. It can have of,
associated with mismanagemen|||f dispo
activities, gj|fcsample be
and be
may be a complex endeavor.
;4p thejihme plan and should be
:^.....&., .tf&r "*
be encountered,
ampteia pit walls). It should establish the
wintered at the mine site, including
'minating the potential future costs
proposed or expanding mining
range of materials that will be mined
in concept, developing and implementing a
Thisapl
characterist
mobilityj^fBmes the
discujjfthe elements'
testiKprogram.
sents
used to determine the physical and chemical
ials, the environmental tests used to assess contaminant
models used to analyze contaminant fate and transport, and
^assurance and quality control engendered in an environmental
ANALYSISliF PHYSICAL CHARACTERISTICS
*.fiif
ifof Analysis
VSf&tKW--
The proposed mine plan should be used to determine the types and volumes of materials
that will be excavated or otherwise disturbed and the management of those materials. This
information, some of which can be presented in the form of maps and cross-sections, provides
the basis for determining the types of characterization studies that will be needed. For example,
if waste rock materials will be used in road construction, then the potential effects on water
c-i
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
quality will need to be ascertained. If the gangue rock at the site consists of several lithologic
types that will be mined in sequence, then the resulting waste rock dump could contain vertical or
lateral changes in rock type that might impact water quality models and geotechnical stability.
Because many material or waste dumps cover significant areas, characterization studies of
substrate materials can determine whether lateral changes in physical properties are present that
could impact dump stabilities and contaminant transport models. Although the physical and
chemical characterization of solid materials can be an intricate process, a well-planned and
executed program can provide the benefits of improved project design and environmental impact
mitigation.
2.2 Physical Parameters
The physical characteristics of waste materials g!|tern their hydrologlp properties and
physical stability. Important parameters that affect poiijj
size, particle-size distribution, particle-size grading,
Important parameters that affect stability include stratific
compaction, moisture retention, shrink-swell potential
existing waste rock dumps and tailings piles, physicalcharact
whether the disposed material contains vertical
to affect the flow of leachate or the stability variati
J
in mining, processing, and disposal
materials as mining progressed; or the e
mineral growth after the materials wer
Particle-size characteristii^m&
through mechanical analyses (sii|e analys|
microns) are determined uslaj|,i|ethods b
analysis) ori optical techniip^i&., Coul
• . ' ; •'f'"
Materials provpes m
additional methodologies
' " '" ^^f^'L'
xmeability metudp-parttcle
and mineral composition.
composition, cohesion,
s. and bulk density. For
ig should determine
properties sufficient
I s
ould arise from changes
of the ore or gangue
;, alteration, and secondary
aameter
ng, size distribution) are determined
fine-gained materials (smaller than 50
settling velocities (e.g., pipette
;). The American Society for Testing and
ining particle-size characteristics (ASTM, 1996);
Sobeketal. (1978).
in particle size normal to a bedding surface) typifies
many waste rock dumttpeoiistacted by end-dumping. Grain-dispersive forces that occur as
•&$ •&' >«£» •$jjT1**' *f '•-••--. £•-.
materials avalanche dowtta^iefTOrking face of a waste rock dump can create deposits that
become coarser upwardiand outward (e.g., Blatt et al., 1980). Changes in particle-size grading
potentially can form preferred pathways for the flow of water through waste rock piles.
if;-'. .
Stratification can be created within waste rock and spent ore dumps and tailings piles by
construction practices. In addition to affecting fluid flow, bedding surfaces can serve as planes
of weakness along which slope failure can occur. The presence of stratification can be noted
from visual observation of existing waste materials or drill cores obtained from these materials.
Methods to measure cohesion, compaction, moisture retention, shrink-swell potential,
Atterberg limits, and bulk density have been developed by the American Society for Testing and
Materials (ASTM, 1996). These parameters are particularly important for assessing the stability
of waste rock and spent ore dumps, tailings piles, and pit benches. For existing waste materials,
C-2
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
vertical or lateral changes in the amount and type of clay minerals can cause many of these
parameters to change throughout a deposit. Consequently, existing waste deposits should be
sampled in several locations and at several depths to determine the range of values that occur.
For those tests that cannot be conducted on materials in situ, appropriate ASTM procedures
should be followed to ensure sample integrity. The stability of waste rock dumps and tailings
piles is discussed in more detail in Appendix F.
->- ••/fc'iSp,"-• -\-:-
estimated through counts of a statistically significant ni
are particularly useful for recognizing mineral
may influence the interpretation of geochemical test
Moreover, they permit identification of reaction
mineral processing (by examining samples "before
techniques, including oil immersion, are well-establisnd and
Sobek et al., 1978; Gribble and Hall, 1993; Crai
X-ray diffraction (XRD) is used
petrographic microscope and to characte
diffraction of an incident beam of X-r
atoms or atomic layers in the cryst
is a quick and easy means to the <
many ore deposits (e.g., Sobek 1978]
sorptive Praties, can da|
fber of points or j
I textures and products that
Ascribed in the next section.
form as a consequence of
sing). Petrographic
(Kerr, 1977;
t are^Sfficult to resolve with a
method measures the
a crystal structure caused by
Bish and Post, 1989). The technique
clay minerals that are associated with
r minerals, which have different
in the design of waste rock and
remediation plans.
coatings that ci
be used to g
knowle
con
be
el&
iM) can be used to image reaction products and grain
ptical (petrographic) microscope. For example, it can
icral growths in the pore spaces of waste materials. This
^models of fate and transport by clarifying the potential for
faces of clays or other minerals. In addition, the technique can
Dr semi-quantitative chemical data on the major constituents of
from a few microns to a few millimeters. The SEM scans a tightly
lergy electrons across the surface of a prepared sample. The beam
fectrons from the atoms in the sample, which are then collected, counted
Image of the specimen surface (e.g., Goldstein et al., 1981). Because the
ich secondary electrons are emitted are unique to each element, secondary
Iso provide compositional data through energy dispersive microanalysis.
Electron microprobe (BMP) analysis is used to determine the compositions of mineral
grains in a sample. The BMP focuses a beam of high-energy electrons onto a fixed spot on a
sample surface (typically 1 to 2 microns in diameter). The beam dislodges secondary electrons
that emit radiation in wavelengths and energies characteristic of particular elements. Similar to
c-3
-------
Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
SEM analysis, EMPs can be operated in an energy dispersive analysis mode. However, these
machines typically are operated using wavelength dispersive detectors, which provide lower
detection limits and more accurate analyses. Because it utilizes a tightly focused incident beam
of high energy, EMP microanalysis is poorly suited for determinations of light elements(atomic
number less than 10) and volatile elements.
3.0 ANALYSIS OF CHEMICAL COMPOSITION
Acceptable techniques for determining the concentrations of i
constituents in solid and liquid wastes are given in 40 CF^ PSft 136.3
detailed in publications by the U.S. EPA (1983; 1986a),Jperican P
(APHA et al., 1992), American Society for Testing andjlfaterials
Geological Survey (Fishman and Friedman, 1989). Cd|i|MeratMS8tts regarding
types of samples that should be tested are described in
occur in concentrations of a
volatile elements, aiid many elei
organic
methods are.;,
ciation^y
fnd
3.1 Analysis of Solids
The chemical composition of solid mate:
be determined using a variety of techniques.
the solid material into a liquid form prior tj
which is a common technique used to
rocks and minerals (Norrish and Chap
The technique analyzes sample
that have been fused into glass)
energy. Excitation by the pri:
with energies,and wavel
emitted (intensity) at a
element. ^X-
igs, or spent ore can
quire solubilization of
X-ray fluorescence (XRF),
chemical constituents of
son and Maxwell, 1981).
as compacted powders or powders
with X-rays of known wavelength and
bns of secondary photons (fluoresence)
elements. The number of photons
proportional to the abundance of a given
le of determining the abundance of many elements that
million. It is an inferior, technique for light elements,
ing at concentrations of less than 10 ppm.
Solid sample;
Ly are solubilized using strong-acid dissolution. Methods to digest
solid materials in nitric acid a&iebmmon and widely accepted (ASTM D5198 [ASTM, 1996];
EPA Method 3051 [U.S?EPj£l986a]). The subsequent liquids can be analyzed by several
methods that most commonly include atomic absorption spectrometry, inductively coupled
plasma spectrometry,,and colorimetry.
In atomic absorption (AA) spectrometry, samples are vaporized at high temperatures and
the concentrations of selected elements are determined by measuring the absorption of light at
wavelengths characteristic of that element (Harris, 1987; Patniak, 1997). The technique is highly
sensitive, comparatively simple, and permits determination of a variety of metals to levels of
parts per million or less. In the direct aspiration method, sample solutions are injected into a
flame, where they are dissociated and made amenable to absorption. The more sensitive graphite
furnace technique uses an electrically heated furnace to vaporize the sample solution. The
graphite furnace technique affords lower detection limits, but is more sensitive to matrix
C-4
-------
Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
interference effects; it works best on relatively "clean" samples (U.S. EPA, 1986a). A primary
disadvantage of the A A technique is that it is time-consuming, because each element must be
analyzed separately (i.e., a sample must be analyzed repeatedly). Accepted atomic absorption
techniques using both methods are given in U.S. EPA (1983; EPA 200 series methods) and U.S.
EPA (1986a; EPA 7000 series). Methods for determining trace metal concentrations at levels of
a few tens to hundreds of parts per trillion were recently developed by U.S. EPA (1996d, f). The
absorption of elements that occur at low concentrations can be masked by interference from
elements at higher concentrations. Consequently, chemical separation is used to isolate these
elements and permit their analysis without interference. The cold-vapor technique (EPA
Methods 245.1 and 245.2, U.S. EPA [1983]; EPA Method 7$70A, U.&EPA [1986a]; EPA
Method 1631 for low detection limits, U.S. EPA {1996a])ijsf|iied to reduce ahdjisolate mercury^
for analysis. The gas hydride method is used to reduce Qjjjj! isolate selenram'(E1PAMethod ,&
7741A; U.S. EPA [1986a]) and arsenic (EPA Method ifflA; U.S.JEPA [198fm];*EPA Method
1632 for low detection levels; U.S. EPA [1996b]) for; "
Method 218.5, U.S. EPA [1983]; EPA Method 7195,
trivalent chromium from solution, permitting measuremi
remaining solution by AA.
In inductively coupled plasma (ICP)
extreme temperatures in an argon plasma.
accelerated toward detectors that measure
(ICP-AES, atomic emission spectrome
spectrometry) (Robinson, 1990). S
of a few parts per billion to parts
of a few to a few hundred parts
permits rapid, simultaneouspr
analytical Sgijsion (i.e., a
interfere
fromlafl
using both1
Method 6020'
"Ultraclean:
IP the pi
§§!&.. *
ofsii
is. ^co-precipitation method (EPA
1986a]) is used toreriiove
ivalent chromium in the
'are ionized at
of material that is
at specific wavelengths
isotopes (ICP-MS, mass
t elements in concentrations
•eloped guidelines permit detection
Ivantage of ICP analysis is that it
f multiple elements in a single
once). Disadvantages include
iiation from other elements, and interferences
: given
*** <%&Sy$%J&!'v
\ (U.S. EPA, 1986a). Accepted standard ICP techniques
. (1986a; EPA Method 6010A for ICP-AES; EPA
[ues low detection limits are given in U.S. EPA (1996e,
f
*Colorimetry is spectrophotometric analysis that uses the absorption of visible
lion (Harris, 1987j|Patniak, 1997) to determine concentration. The technique uses a
rophotometer orjpter photometer to determine the concentration of a constituent in a
Jly preparedjlpeous solution by measuring the absorbance at a specific visible light
llepted colorimetric technique for hexavalent chromium (EPA Method
_i U.S. EPA (1986a). Colorimetric techniques also have been developed for
i, nitrate plus nitrite-nitrogen, ammonium nitrogen, and total cyanide.
3.2 Analysis of Liquids
Samples of waters and wastewaters typically are filtered in the field prior to analysis.
Methods developed by EPA require filtration using a 0.45 urn filter. Care should be taken when
C-5
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
reusing field filters to ensure that they do not become sources of contamination. Importantly,
some colloidal particulates can pass through this filter and will report as dissolved constituents in
water quality analyses. Because some of these constituents (e.g., iron oxyhydroxides) readily
adsorb metals from solution, the presence of colloidal particles smaller than 0.45 um can
influence measurements of dissolved metals such as cadmium, copper, lead, and zinc.
Liquid samples may be analyzed as collected, but they typically are treatedfollowing
collection to preserve their chemical constituents. In many cases, multiple splits^ȣa given
sample are preserved using a variety of techniques. Electrical conduct^^an||pH should be
measured on untreated samples at the time of collection. must be
delivered to a lab for analysis of their inorganic and to ^
preclude precipitation of metal compounds or the volatijifliion betweejf
the time of sample collection and analysis. Samples cc
acidified to pH <2.0 using nitric acid and stored at 4C
constituents (EPA Method 200.0; U.S. EPA [1983]).
analysis should be adjusted to pH >12.0 using sodium'.
formation of hydrogen cyanide (EPA Method 335.3;
analysis of their organic constituents should be pres
with sodium thiosulfate (EPA 3500 and 5000 serin
cted for total meta
••!%*
lissolution oi
samples collecte
Many metals in ambient waters
which are below the detection limits of
determinations of background water
(U.S. EPA, 1996h). This method
by newly developed "ultracleari
1996a-g). Using these sampling
water can be determined atiaNfM of a fe
Ibe
Tcyanide
|d stored at 4°C to prevent the
Samples collected for
[treated or treated
6a]).
tan 1 part per billion,
imques. To permit accurate
released draft Method 1669
ecting samples that will be analyzed
matographic techniques (U.S. EPA,
f, trace metal constituents in ambient
idred parts per trillion.
Prior to analysis, cn^amescoBstituents are separated using solvent extraction or purge-and-
trap techniques. Nonvolatile aa&sena-volatile organic compounds are extracted using solvents
such as methyleae chloride and^odkapes that include liquid-liquid extraction, soxhlet
extraction, or ultrasom^xteactiontEPA 3500 series methods; U.S. EPA [1986a]). Volatile
organic compounds"alplSft§^Bd by bubbling an inert gas (either N2 or He) through the sample
solution to liberate the \siffi|^®omponents which are trapped in a sorbent column (EPA 5000
seriesmethods; U.S.
The concentrations of metals and other inorganic cationic constituents in samples of
surface water, ground water, waste rock leachate, or mine drainage are analyzed using the AA,
ICP, and colorimetric methods described above. Other techniques used to analyze aqueous
samples include titrimetry, gravimetry, ion-selective electrode analysis, ion chromatography, gas
chromatography, liquid chromatography, and Fourier transform infrared spectroscopy.
Titrimetric analysis is used to measure the acidity and alkalinity of aqueous samples
(Patniak, 1997). Acidity is measured by titrating a solution to a predetermined pH endpoint
using sodium hydroxide (EPA Method 305.2; U.S. EPA [1983]). Alkalinity is determined by
titrating a solution to a predetermined pH endpoint using a strong acid (EPA Method 310.1; U.S.
C-6
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
EPA [1983]). In both cases, the amount of titrant is converted to milliequivalents of acidity
alkalinity per liter of solution.
or
In gravimetric analysis, the mass of a reaction product is used to determine the quantity of
the original analyte (Harris, 1987). Although these techniques are among the most accurate in
analytical chemistry, they are no longer widely used because they are time consuming. However,
gravimetric analysis remains the most common method for determining total dissolved solids
(IDS) and total suspended solids (TSS) in a sample. To determine these parameters, a sample is
filtered through a standard glass fiber filter. The filter is dried and weigfed, wi3?the weight
increase representing TSS concentration (EPA Method, 160.2; U.S. EEi^§3]). Total
dissolved solids are measured by evaporating the filtrate and weighinpi^l|piual solids (EPA
Method 160.1; U.S. EPA [1983]).
Ion-selective electrodes respond to a single ioni^peciesJuS solution i
Patniak, 1997). The electrodes measure the electrical pke^i|ifference across
between a solute at constant chemical activity within the'eleclro^fnd the activity of the solute
in the solution of interest. Ion-selective electrodes canjbe the concentrations of
fluorine, cyanide, and ammonia in water samples (Standard APHA et al.
[1992]).
developed
a wide variety'
by an inert
Organicjlinipounds"'
Chromatographic techniques, in •
another to permit their identification, inc
high-performance liquid chromatogra|
concentrations of common anionicjpnltituent
technique uses a series of coll
solution and combine them wit
electrical c(||ductivities i
condi
chromium by ion chromatography was recently
fterest are separated from one
;as chromatography, and
s used to measure the
d 300.0; U.S. EPA [1983]). The
resins to separate the anions from
:arris, 1987; Patniak, 1997). The
variably strong electrolytes, are
anion concentrations can be determined. A
romatography is used to measure the concentrations of
is technique, a liquid sample is vaporized and carried
with a partitioning material (Harris, 1987; Patniak, 1997).
in the column by their variable affinities for the partitioning
Int compounds have discrete retention times prior to emerging
matenlifwhich. causes •
column and a detector. Several detector types are employed including
eMrolytic conductiviAetectors, electron capture detectors, and flame ionization detectors
8000 series U.S. EPA [1986a]). More sensitive detection can be accomplished
: mass (EPA 8200 series methods; U.S. EPA [1986a]). Constituents that
'feted by mass (i.e., isomers) can be distinguished using Fourier transform
vscopy, in which isomers are distinguished by their infrared absorption
Method 8410; U.S. EPA [1986a]). High-performance liquid chromatography
also is used to measure the concentrations of organic constituents. This technique uses columns
filled with adsorbent material (typically microporous silica with a covalently bonded stationary
phase) to separate the compounds of interest, which are then eluted from the column by solvents
(Harris, 1987; Patniak, 1997; EPA 8300 series methods, U.S. EPA [1986a]). Liquid flow is
accomplished under high pressure to increase efficiency of the system. Absorbance, refractive
C-7
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
index, and polarographic monitors are used to detect solutes eluted from the column. Potential
interferences occur in all chromatographic techniques when two or more solutes have similar
retention times in the separation column or, for mass spectrometry, have similar masses.
4.0 ANALYSIS OF CONTAMINANT MOBILITY FROM SOLIDS
Rigorous geochemical testing programs can reveal whether the rocks exn@ijid by the
mining process or the wastes and materials produced by extractive opeAonsjffilikely to release
metals or other contaminants that could degrade the environment at oA
/•*"•'.'„ :.'•'•-• £^*
Testing programs are aimed at determining the potential MiiiM gem
release through weathering and leaching. Because thesejp>oratory p
manner intended to speed natural processes, test resultsifiust be interpreted
Particle size and mineralogy play pivotal roles that govern the long-term beha\
the environment. Consequently, these variables shouldjaot %& ignored by a testing
Considerations regarding the number and types of samples $|at should be tested are described in
Section 6.0. "
ing a mine site.
onstituent *,,
j&ffi
.ducted iifia
als in
4.1 Mineralogical Considerations
It is critical to understand the mine!
in order to establish a sound geoehemica|estmg pj
gangue materials are chemically and rn0eralogic|lly
and tailings piles), selecting approlaltl test
composition, abundance and
especially important for potenti
sulfides (e.g»^galena),
s, and spent ore materials
many ore deposits and their
test results|(essg?^iays
a significanlJiirj^aCtflcai the
epithermal dep^sM;fl^!ting
' ' "' ' ' '"'
secondary
environmental behavi
true of some waste rock dumps
knowledge of mineral
itial variations in mineral abundance is
*., pyrite), nonreactive but leachable
T, jarosite and gypsum), readily soluble and
(e.g., siderite), and other minerals that may affect
Smith et al. (1994) showed that alteration zoning can have
content of drainage generated from a quartz-alunite
to recognize the mineralogical changes that
-
impaiii3 to a given rock unit and characterize the range of
occur as a result.
:« Mineralogical steiiesiprovide a framework for interpreting the results of the geochemical
tests outlined below. For example, hydroxide coatings on calcite or sulfate coatings on pyrite
may preclude these minerals from participating in acid neutralization or generation in existing
waste rock dumps,,; Samples of this material that are crushed to fine particle sizes prior to acid-
base accounting tests may exhibit net neutralization potentials significantly different from that of
the in situ waste material. Having knowledge of mineral coatings would allow one to interpret
the test results in a more sound scientific manner. Mineralogical studies also can provide
information regarding the sorptive properties of host minerals (e.g., clays) which could allow a
determination of whether they are likely to retard the movement of certain contaminants. Studies
of mineral compositions could permit identification of the mineralogical sources of trace metals
in leachates and provide a basis for designing effective disposal plans.
C-8
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
4.2 Physical Considerations
The ability of a material or solid waste to generate acidity or alkalinity, or to contribute
metals or other constituents to the environment through leaching, depends partly on the particle-
size characteristics of the waste material. Interpretation of test results is complicated if the
particle size of the test materials differs significantly from the particle size of a waste material as
it is or will be disposed of in the environment. Particle-size characteristics impact both reaction
rate and reaction duration by affecting the reactive surface area, the distances between potentially
reactive particles, and the porosity and permeability of the waste.
'counting tests*
^IF
sizes -"
iae^crashing
Test materials that are finely ground can impact th^^ftlts o
(Robertson and Broughton, 1992; Lapakko et al., 1998)jpLishing t
increases the surface area of reactive sulfide and neut
can increase the acid generating potential of a sample
enclosed in inert minerals (e.g., pyrite enclosed in qi
oxidation in coarser materials (Lapakko et al., 1998).
and neutralizing particles is greatly diminished in
formation of localized zones of low pH that are kno\
piles (Robertson and Broughton, 1992).
g mim
easiitfreactive sul
ich would not be?
4.3 Aci
generate
the atmosph
asjarosite.
accelerai
oxi
T;
sed to
jbetween reactive particles
Is, which may inhibit the
led waste rock
The leaching characteristics of wasjpnatera
size. Smaller particle sizes increase mejjpSace are
Moreover, smaller particle diameters smaiyfrrange <
pore sizes and permeability, both inf^pice the
pore spaces of granular materials^feflie amJlnt of 1
by changes in particle
enable to leaching.
e sizes (better grading) affects
c of extraction fluid held in the
it is retained by the material.
Jfide minerals such as pyrite, marcasite, or pyrrhotite can
^example, humid air) and an oxidant (either oxygen from
^as ferric iron). In addition, some sulfate minerals, such
)lutions (e.g., Lapakko, 1991). Bacteria commonly
icration from sulfides by enhancing the rate of ferrous iron
"ckson, 1983) or the rate of reduced-sulfur oxidation (BC AMD
rea
which acid is generated depends on the composition of the sulfide
id Silver, 1980), its crystal size and shape (surface area; Caruccio et al.,
faction coatings that may form on the surfaces of sulfide minerals
lolson et al., 1990; Sherlock et al., 1995), and the environmental
le, pH, humidity, oxygen fugacity, temperature) at the site of oxidation (BC
5", 1989). In general, acid generation involves a rather complex set of chemical
change through time (BC AMD Task Force, 1989).
The potential for acid generation is offset by the ability of a material to neutralize acid.
Acid neutralization is imparted by various minerals including calcium-, and magnesium-bearing
carbonates, oxides and hydroxides of calcium, magnesium, and aluminum, some silicate
minerals, and some phosphates (Sherlock et al., 1995). In general, dissolution rates (and hence
C-9
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
neutralization) are considerably faster for carbonate minerals than for other neutralizing minerals.
Factors that influence mineral dissolution rates include pH, dissolved carbon dioxide content,
temperature, mineral composition, crystal size and shape, redox conditions, and the concentration
of "foreign" ions (e.g., trace metals) (Sherlock et al., 1995).
Static predictive tests are used to define the balance between potentially acid-generating
minerals and potentially acid-neutralizing minerals in a sample (BC AMD Task Force, 1989).
These tests, which are quick and comparatively inexpensive, cannot be used to predict the quality
of effluent that may drain from waste materials in the future. However,-they are useful for
determining which geologic units have the potential to generate acidity and, in essence, serve as
positive/negative indicators of the theoretical potential for;|^l§*generatk«a (fR^bertson and ^
Broughton, 1992). When coupled with mineralogical antfetrologicai data'ft^H^te test ^
samples, certain static test procedures can provide somjjpeasure o|^ieutralizalk«i^e (Millsr
1998a). Kinetic tests are used to define reaction rates
conditions. These tests are significantly more expensh
complete.
v / ^ J
'• under specifce»i|iroiirnental
t , i *•*
take months or years to
•&&91K&&' '
In general, acid mine drainage testing programFutilize
static tests of numerous samples are used to ident^||f|gntially al
and to characterize the variability that occurs
deemed representative of the range of com
whether acid drainage will occur. Althoj
1990; 1996) have specific guidelines nifndating jpfiic andl
states of EPA Region 10 have not adopted a similar appr
^ ?
4.3.1 Static Tests , f'7
iproach in which
ing geologic units
ictic te^Mre then run on samples
reactive units to determine
996) and Nevada (NV DEP,
testing of mine wastes, the
Static test methods, wMch were developeirimtially to determine the potential for acid
generation fromcoal mine wastes, have been adapted for use in the metal mining industry. The
variety of static teM methods ^tatSrepstvailable are collectively referred to as acid-base accounting
1 & *» "f
(ABA) analysesf^afictest methoeta&gies are described and evaluated in reports by Lapakko
(1991; 1991), Law^oce and Wang (1996), and Mills (1998a; 1998b); digestion methods are
compared and evaluated.mSkdusen et al. (1996). Table C-l summarizes several of the more
commoaily used test me
434.1 Acid-Base Accounting Tests
•*' Specific procedures for conducting acid-base accounting (ABA) tests are compiled in
Mills (1998a; 1998b). Although a few tests produce a single value that can be used to indicate
the likelihood for acid generation (Section 4.3.1.2), most static tests determine separate values
for the acid generating potential (AP) and acid neutralizing potential (NP) of a sample. These
values, expressed in units of tons of CaCO3 equivalent per kiloton of material, are used together
to indicate whether a sample has a stochiometric balance that favors net acidity or net alkalinity.
In general, determinations of acid generating potential are relatively straightforward. This is not
true of tests to measure neutralizing potential. The problem stems from the widely variable
solubilities and reaction rates of minerals that have the potential to neutralize acidity (e.g.,
c-io
-------
Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
carbonates vs. silicates), the relative differences in aggressiveness of the various methods used to
determine neutralization potential, .and the different titration endpoints employed by each test
(e.g., Mills, 1998a). Studies in which the neutralizing potential of a sample was determined
using different methods concluded that the NP value is highly sensitive to test methodology (e.g.,
Lapakko, 1994). Consequently, it is important that any program established to test wastes and
materials prior to or during operation use a single test method to ensure that the program
produces data that are internally consistent.
jt$i&
43.1.1.1 Methods to Determine Acid Generating Potential
Acid generating potential is determined from the
weight percent). This value is converted to acid genera
factor of 31.25 that is derived from the molar stoichio
reactions. The conversion factor assumes that all repo
completely oxidized to sulfate and ferric hydroxide,
oxidation reaction are neutralized by CaCO3. Acid gen
of CaCO3 equivalent per metric ton of sample (also ex
equivalent per kilotonne of material).
Samples typically contain sulfur in
generating acidity. The sulfur speciation
methods to determine sulfur content.
(O'Shay et al., 1990) and reactive sul
>le (expressed in
ipaglying by,
itiorn
as pyri^^ill^fte is
ions producWlti the
is reported in kilograms
if metric tons of CaCO3
y
which are capable of
the most commonly used
hydrogen peroxide method
Sobek et al. (1978) descrj
sulfate sulfur, HNCyexrractabl
require a crushed
a
e the total sulfur, HCl-extractable
.c sulfur contents of a sample. The tests
mesh (0.25 mm), which is split into
Leco sulfur analyzer. One split is left
total sulfur content of the sample. A second split is
with HNO3. Acid-extractable sulfate sulfur (e.g.,
difference between the total sulfur contents of the
soluble sulfide sulfur (e.g., pyrite) is computed from the
contents of the HCl-treated and HNO3-treated splits.
omputed as the total sulfur content of the HNO3-treated split.
ntages that include the potential removal of highly reactive sulfide
leached wi
gypsum and al
untreated
differengipetween
Nonejpfctable organic"
methods have _?
and the potentiAondetection of sulfide that is slow to oxidize under experimental
|tions, but vAacbfay form acid in the environment (BC AMD Task Force, 1989).
f
Qt to recognize that sulfur speciation tests like those described above do not
i-msoluble sulfates, such as barite or jarosite, which will report as sulfide sulfur.
containing significant quantities of these minerals will appear to have more
sulfide sulfur than they actually do. Although acid-insoluble sulfates will not oxidize to produce
acid, some of these minerals (e.g., jarosite, alunite, and melanterite) may dissolve, hydrolyze, and
generate acidity (Carson et al., 1982; Mills; 1998a). Mills (1998a) states that whole-rock barium
concentrations can be used to correct sulfide sulfur determinations when barite is present.
However, barium also may be present in common alteration phases such as potassium feldspar
c-n
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
and biotite (Deer et al., 1992). Consequently, caution must be used when applying a barium
correction of this type. As pointed out by Mills (1998a), it is rarely acknowledged that each step
in the sulfur speciation tests introduces analytical error; these errors are cumulative.
Table C-l. Summary of Commonly Used Static Test Methods.
Static Test Method
Reference
Comments
Sobek
Sobeketal. (1978)
AP uses sulfjir speciatio
NP uses feSlest and
and mosfisilie'ate mine:
5coiv^ t(*'
OOl V G Id
lalyzer.
it dissolves carbonates
endpointof7.0r
:st case" value*
Modified Sobek NP
Lawrence and Wang (1997)
1 at ambi
reactive silJ
ff5aOH
;.3. Less aggressfttijjgpKe to use of
;eacid. Lapakko( 1992) suggested that
idpoint may lead to overly optimistic
Sobek NP Siderite Correction
Skousenetal. (1997)
; hydrogen peroxide
ferrous iron from
i alkaline NP than standard
is abundant.
BCRI Initial
Duncan and Bru>
(1979)
Leco furnace or wet chemistry.
IP uses^^^aaed to pH 3.5 at ambient temperature
that dissoMlPcarbonates and possibly limonite and
chloriteJlfves "most likely case" values.
Lapakko NP
NPjKJis H2SO4 added to pH 6.0 at ambient temperature for
week that dissolves carbonates; gives "worst case"
Hue.
. (1997)
Paste pH
t al. (1982)
Crushed sample is boiled with hydrogen peroxide then
titrated to pH 4.5 with NaOH. NAG value, expressed in
units of kg H2SO4/tonne, provides indication of potential
for net acidification.
M^^^H^^^^^^^BIflMMaMM*BHVHIWH^HIMH
Sample is mixed with water and pH measured by meter.
pH value provides indication of potential for net
acidification.
Summaries include informatio
Iills(1998aandl998b).
The hydrogen peroxide method (O'Shay et al., 1990) has been used to determine the
pyrite content of coal mine wastes. In this test, a sample crushed to particle sizes smaller than
150 microns is soaked in HC1 for two hours to remove carbonate minerals. The treated sample is
mixed with hydrogen peroxide and pH is monitored at intervals of 1 to 2 minutes. Curves of pH
versus time are compared to curves generated from synthesized standards. Potential acidity is
determined using the conversion factor of 31.25.
C-12
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Reactive sulfur tests treat sample splits with hydrogen peroxide to oxidize sulfide
minerals to sulfates. The sulfate content of the peroxide leach solution is used to determine the
amount of reactive sulfur, which is converted to potential acidity using the conversion factor of
3 1 .25. Producing accurate results with this test method, which is not widely used, requires strict
temperature control (Hinners and SAIC, 1993), because pyrite decomposition is exothermic.
4.3.1.1.2 Methods to Determine Acid Neutralizing Potential
.>^Y\
A variety of procedures are used to determine the neutralizing p^ntial of a sample
(Table C-l). In general these methods involve reacting a sample with^@^m quantity of acid,
determining the base equivalent amount of acid consumed:|||ihe
measured quantities to neutralization potential (NP), whj|Rs expresseirstoraies
CaCO3 equivalent per kilotonne of material (Mills, 19$
The Sobek and Modified Sobek methods, whic
procedures, both use a "fizz test" to determine the quantf
determination. In essence, the test consists of adding
of test sample and subjectively assigning a fizz rating
to the resulting effervescence. Each of these rati
normality of acid that is added to the sample
and Skousen et al. (1997) conducted studiegSre
JSP'
ratings when determining Sobek NP valiHfsfor a vje
NP values could differ by amounts aried fift a few
one or two category changes in fizapn|ag.
the most wideFJMised
will be used in the NP
f acid to a small quantity
.oderate", or "strong"
snt quantity and/or
ice and Wang (1996)
signing different fizz
Their results showed that
it to a few hundred percent for
Neutralization potential by th
by treatingJ|e sample with^^Sess of
of unc
by with hot acid and titrated to a pH of 7. In the
odified Sobek methods is determined
icid and then titrating with sodium
acid. In the original test procedure outlined
Ldure Research (1989), the sample is agitated with
for to a pH of 8.3 (cf., Lawrence and Wang,
ipunt base is converted to a calcium carbonate equivalent
l|on of sample (also expressed in units of metric tons of CaCO3
Modified
acid at room
1997). Inb
in units (^Kilograms'
'equiyjpSit per kiloton
The Sobek and modified Sobek tests determine the maximum amount of neutralization
itial available injfsample, but do not predict the rate of neutralization nor indicate the pH to
ta sample ca^pun-alize acidity. Lapakko (1992) showed that both tests provided a fairly
for samples composed of quartz, alkali feldspar, and mica, but
in samples with abundant calcic feldspar, chlorite, clay, pyroxene and olivine.
SiffilPlofclusions were drawn by Skousen et al. (1996) who showed that NP estimates for a
single sample could vary by an order of magnitude depending on sample mineralogy and
digestion method. Other criticisms of the Sobek and Modified Sobek methods (see Lapakko,
1991; 1992 and Hinners and SAIC, 1993) include: 1) the small particle size used in the tests may
produce unrealistically high values for NP, 2) hot acid which is mixed with water and heated to
boiling in the Sobek method may increase analytical scatter, 3) hot acid may digest siderite (iron
C-13
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
carbonate) and clay minerals that increase NP values but provide little alkalinity, 4) NP may be
overestimated because pH is back-titrated to values of 7.0 or 8.3, not 6.0 which is a typical water
quality standard, and 5) NP may be overestimated if metal hydroxides precipitate during the
addition of the sodium hydroxide base.
The BCRI Initial test (Duncan and Bruynesteyn, 1979; Bruynesteyn and Hackl, 1984) and
Lapakko NP test (Lapakko, 1994) both use sulfuric acid at ambient temperature to (determine
neutralizing potential; neither test requires a subjective fizz test rating. In both teslst the sample
is suspended in water and acid is titrated into the suspension until a stera^.pre^|Merrnined pH
1 * 1 " 1 IT™«1 T^ ^•"tT^T "T • , • 1 , i . • . , * 1 * . f* ^ /SP^&isS'f'^-il'•>?,•'''$$&"'•'. it T 11
value is achieved. The BCRI Initial test uses a titration endj»oint of
procedure uses a titration endpoint of 6.0. The volume of jH^ed ac
jsr^KC1'
for acid consumption, which is expressed in units of kilojpms per tq
'.'!,* ,.',$>' ^
particularly aggressive in dissolving minerals in additioilto the carbonates.
f * wt? w ^i^ i^"y
higher titration endpoint of the Lapakko procedure mali||| tiie>^6st conserv;
estimate) of the static NP test procedures. Lapakko that the BC
overestimated NP for samples containing significant
the Lapakko NP
.compute a value
significant
interferes
Two alternative methods have been developed^ dete:
although they apparently are not in widespread usMifillkalkaline
developed for use by the coal mining ind
microns is mixed with HC1 and allowed
is then titrated to pH 5.0. Although this
minerals (e.g., siderite), it may not perpft reacti
the sample (Coastech Research, 19jfWDurini
in acid in a sealed chamber. Th
basic solution and measured usj
content of thesample is dj
converted t8;!%CO3 eq
(new
izing potential,
potential test was
rushed to minus 23
"temperature. The mixture
of less reactive carbonate
"ering carbonates present in
analysis test, a sample is digested
evolved by reaction is absorbed into a
D Task Force, 1989). The carbonate
f CO2 gas evolved, with the result
4.3.1.2 Static Tests
advantage of determining only the carbonate
jjo 5.9. However, the test cannot be used if a sample contains
mineral will react to form sulfur dioxide gas that
Task Force, 1989).
ce a Single Indicator Value
w Two test procedtffe^Kive been developed that provide a means for quickly indicating
whether a sample is likely to have a stoichiometric balance that favors acid production. The net
acid generation (NAG) test (Miller et al., 1997) uses a peroxide solution to oxidize sulfide
minerals to sulfate&|The oxidation process produces acid which reacts with alkaline minerals in
the sample. .Upon complete reaction, the solution is titrated to pH 4.5 using NaOH. The volume
of titrated NaOH is used to compute a NAG value, which is expressed in units of kg of H2S04
per metric ton of material.
Paste pH is a simple and inexpensive method to indicate the presence of reactive
carbonate or readily available acidity. In this test, powdered rock and water are mixed in a
specific ratio to form a paste. The pH of the paste is determined using a pH meter and pH
C-14
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
reference electrode assembly. The test offers no indication of the relative proportions of
acidifying or neutralizing components in a sample (BC AMD Task Force, 1989).
4.3.1.3 Interpreting Static Test Results
Static test results provide a preliminary indication of whether a sample is likely to
produce acidic drainage in the environment. These tests do not, however, provide any data
regarding when acidification may occur or the rates at which acid generation andrrieutralization
reactions will proceed. As such, they are useful only for screening samjtes fbrjmeir potential
behavior. It should be kept in mind that most static tests are^nduct^^fe^^ushed or
pulverized samples that may have particle sizes significanl^^ialler !r|piia^Hals as they
be disposed of. This can significantly change the chemi^^vailabilifi^'^i^i^.rninerals.iEis
described in Section 4.2. In addition to these factors, iawpretatio:
knowledge of sample mineralogy.
Static test results are generally interpreted withinl
established from experience in the coal mining indust
neutralization potential and ratio of neutralizing potential to acH
values given in Table C-2 provide general guideU»|K^iterpre
should be viewed in light of the sulfur si
enough pyritic sulfur to produce a quantity^^lad the environment even in
the absence of neutralizing materials). can and do occur,
kinetic tests should be conducted to ccaprrn the jlatic test!
gaily developed framework
is are based on the net
potential. The
5St results and they
Tes may not contain
Many static test interpret
the total sulfur content of a:
measure of^gdification pj
less estir
has
(Mills, 1998a)?
stoichiomet
significadil" greater i
fact, workers advl
;rec
:tor I
.•^BuJjr
lue for agflr generating potential computed from
most conservative (highest AP value)
"sulfur values provide more realistic, but
because these analyses do not report
iting (e.g., gypsum). The Canadian metal mining industry
standard method to compute acid generating potential
iat the assumptions inherent in the derivation of the
additional uncertainty, since the factor could be
31.25 (BC AMD Task Force, 1989; see Section 4.3.1.1.1). In
a value of 62.5 (Brady et al., 1990).
C-2. Suggestedjiuidelines for Static Test Interpretation.
Potentially Acid Generating
Uncertain Behavior
Potentially Acid Neutralizing
NP/AP
< -20 tonnes/kilotonne
<1
> -20 to < +20 tonnes/kilotonne
Ito3
> + 20 tonnes/kilotonne
>3
C-15
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
The net neutralizing potential (NNP), which is defined as the difference between the acid
neutralizing potential (NP) and acid generating potential (AP) of a sample, is computed by
subtracting the latter from the former (NP-AP) when both are expressed in units of kilograms of
CaCO3. equivalent per metric ton of material (or metric tons per kiloton). In general, samples
with NNP exceeding +20 kg/tonne are considered to be non-acid-generating (Robertson and
Broughton, 1992). In contrast, samples with NNP less than -20 kg/tonne are considered to be
potentially acid generating (Robertson and Broughton, 1992). Samples with NNP yalues
between these two cutoffs occupy an area of uncertainty and should be tested kinetically to
determine their acid generating capability (Robertson and Broughton, 1992). Although the +/-20
cutoff values are generally accepted by most workers, some researchers Aave advocated less
stringent values for some mine wastes (see discussions in Lapakko, 1991; ,1992 and Hinners and
SAIC, 1993). v' yo g f
The ratio of acid neutralizing potential to acid gflbatinjg-jpotential (NPMJR)^aiso is
computed from static test results when both are expresse3fta units of kilograms of CaCO3
equivalent per metric ton of material (or metric tons per kiloton). $Jn general, samples with
NP/AP exceeding 3 are considered to be non-acid-genemting*p^o8i^^pn and Broughton, 1992).
In contrast, samples with NP/AP less than 1 are considered to
(Robertson and Broughton, 1992). Samples wii
of uncertainty and should be tested kineticall;
etween
eir aci
4.3.1.4 State Recommendations
The States comprising EPApSgion
guidelines for conducting static teSpoT mini
DEP, 1990) recommends use
potential and either the So
1990) to determine acid|
percent (NOrV^J'^) are o
DEP, 1990)^^|g^fe&th
New Mexico reoonim&ds deti
Sobek
(1978;
potem
acid generating
itoffs occupy an area
crating capability.
e not established formal regulatory
'aterials. The State of Nevada (NV
icthod to determine neutralization
ide method (presumably O'Shay et al.,
samples in which NP exceeds AP by 100
m-acid generating and do not require additional testing (NV
s criteria should be tested kinetically. The State of
acid potential of representative samples using total
sulfur and the neutralization potentilpfsing either the ABA, modified ABA, BCRI, or alkaline
production methods (f^MED, 1996). Kinetic tests are suggested for those samples with NP/AP
ratios less than 3. Samples witPratios exceeding 3 are considered non-acid generating. The
states of Nevada and New Mexico illustrate that states may view different test methodologies as
acceptable. Applicants should check with state agencies to determine whether they have
preferences that may not be codified.
433 Kinetic Tests
Kinetic test procedures are designed to accelerate the natural weathering process in order
to provide information about the rates of acid consumption and acid production over time. A
variety of kinetic test methods are available, including conventional and modified conventional
humidity cells, SRK humidity cells, soxhlet extractions, column leach tests, shake flask
extractions, modified B.C. Research tests, simulated environment studies, and field lysimetef
tests; humidity cells and columns are most commonly used by the mining industry. According to
C-16
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Lapakko (1991), there is no single test that produces all of the chemical information needed to
evaluate all mine wastes under all conditions of disposal. Most of the kinetic testing procedures
are complex, time-consuming, and require considerable operator skill to produce consistent
results.
4.3.2.1 Kinetic Test Methods
The various kinetic tests described below are similar to one another in that jfearnple is
subjected to periodic leaching, the leachate is collected and analyzed, a||rates; Jf acid
generation, metals release, and neutralization capacity depletion are c«jf|f|||&if The methods
differ in the amount of sample used in the test, the particl^^Pof the^l^^^^^erial, test
conditions (lab vs. field), and test duration. Although na^^ecifically^^i|ft^^^); procedures,
it is typical for splits of the starting sample and final le * -*«,„,» ^
base properties and total metals; mineralogical analys
samples because these data can provide important coi
results (Mills, 1998c).
ted prodptt/to be te
shojira be conduct©!
1989).
discussion^
The.
sample s&rSaA. largl
generailysimilar to thel
^ij^w**.^.-
isist the interprefSibn of test
4.3.2.1.1 Conventional and Modified Conventional Humi
The conventional humidity cell (Sob
comparatively small amount of sample
mm. A split of the sample is analyzed f<
of water quality from the tests. The
over the sample for 3 days, followjifPrfJ"moist.
flushed with a specified volume
the pH of the water may be adii^pl to sli
for siilfatejsjj[, acidity,
10 so:
3ns of
1.3.2.2
e test that uses a
e sizes smaller than 2
ints to assist in the evaluation
astic box and dry air is passed
w f Every seventh day, the sample is
mulate thfe^composition of regional acidic rain,
The leachant is collected and analyzed
and This 7-day process is repeated for
may reaction period (Coastech Research,
used commonly in the metal mining industry (see
jjjtionaTlBSidily cell designed by Lawrence (1990) uses a bigger
jjf water for the flush cycles. The test is conducted in a manner
* Itthod.
MIL-
ASTM procedujifD5744-96 (ASTM, 1998), which was designed specifically for mining
i and materials,, Jpls a modified column as a humidity cell. The test is conducted on a
i of samplejfpiished to particle sizes smaller than 6.3 mm. The test is run for 20 weeks in
I'fhe Sobek method, with 3 days of dry air, 3 days of moist air, and a weekly
yl .0 liter of water. The procedure includes provisions for pre-leach and post-
afogical and chemical characterization of the solid sample and directions for
preparation and use of an optional bacterial (T. ferrooxidcms) spike.
Few data are available to document the reproducibility of humidity cell data (Mills,
1998c). Experiments designed to test the validity of conventional humidity cell results for
tailings and waste rock samples are summarized in Lapakko (1991; 1992). In general, the
C-17
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
conventional humidity cell is able to indicate many of those samples that become acid producing.
However, some validation tests noted indefinite pH trends that were difficult to interpret and
some tests failed to predict acid generation, suggesting that these experiments should have
continued for longer durations to permit depletion of the neutralizing capacity. Criticisms of the
conventional humidity cell are given in Broughton and Robertson (1992). These authors argue
that the small particle size used in the tests masks the influence of particle size on acid
generation, making them unsuitable for waste rock samples; however, the particle sizes used in
the tests are similar to tailings. Moreover, they point out that the complete sample flush may
affect the development of local low pH and disrupt the natural storage ap&d flushing of oxidation
products. Other workers, however, feel that the small particle size isa^^feriting factor since
the most highly reactive products in waste rock piles typically occur iniiijpHaHer size fractions^
(Hinners and SAIC, 1993). For existing waste rock duinjfs* Price (l^^fe&os^^ds using o|fly
the sub-2 mm size fraction of (i.e., crushing larger clas|
tests. For proposed waste rock dumps, Price (1997) re|
80% less than 6 mm. Clay-rich samples can pose probl
clay particles can be easily lost during weekly flushing
the loss of fine materials (Mills, 1998c).
lould bejsvoided) i
lendjIKrushing drif
4.3.2.1.2 SRK Humidity Cells
A
Broughton and Robertson (1992) present a
humidity cell) designed to test coarse wajjfe'rock sapp.
sizes smaller than 10 cm which is placejfinto a cgjmdric
-^ -^^L'^' fi', ^
height of 45 cm. Humid air is cycl^Bpnstantlpfiirough
al to
.umidity cell testmg^il!cause the
clog filters used to prevent
several points along the upper
discrete pathways. The volum
encounteredbfin the field.
./*• *%
used as fluslrwater in
te rock^
The
areas of low
fraction moreifcl
neutralizing minerals
idigfcell (termed the SRK
^uses material crushed to
with a diameter of 30 cm and
cell. Flush water is introduced at
1
that it percolates downward along
ipproxlaiates (per unit area) conditions
leach water from one test cell to be
i wr
lete flushing of the oxidation products, permitting local
oelT (Broughton and Robertson, 1992). The coarse size
dmatesMthe separation distance between acid-producing and acid-
pock samples.
4.3.2.1.3 Soxhlet Extractions
Soxhlet reactorsTecirculate water or other fluids through a sample to simulate conditions
of weathering. The method of Sullivan and Sobek (1982) uses distilled water at 25 °C to leach a
sample over a period of six weeks, although the test duration can vary. A technique described by
Renton et al. (1988) uses as the leach material a pulverized coal waste sample that has been
oxidized in an oven. The sample is leached in a soxhlet reactor with distilled water at 85 °C and
the leachate is analyzed for water quality parameters. The sample is returned to the oven for
additional oxidation prior to the next leach cycle. The oxidation-leaching cycle is repeated 5
times.
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Soxhlet extractions require sophisticated equipment and considerable operator skill,
especially for the Renton et al. procedure. Evaluations of the Sullivan and Sobek (1982) method
by Coastech Research (1989) indicate that it may provide reliable results for tailings samples.
The aggressive oxidation of samples and elevated leaching temperatures used in the Renton et al.
method tend to overestimate the acid producing capability of a sample by accelerating the
dissolution of carbonate minerals (Bradham and Caruccio, 1990).
4.3.2.1.4 Column Tests ,1^
Column test procedures have not been standardized JMills, 199Sc). Consequently, they
are highly flexible tests that permit a range of column desj||sptest mkenal characteristics, and „..
flow rates. Column tests can be conducted in a manner jfflilar to conVerrfiomaiJHHnidity cells,
but they can also be run in an "upflow" mode to simula^subaquejp-disposal or as subaerial
columns without forced oxygenation (i.e., the top of th^^hminJ^bpen but air%lot forced
through the sample) (Mills, 1998c). Columns, which diameters of 15 eln and
lengths of up to 2 m, can be constructed with larger to accommodate larger
sample sizes (10 kg to 3 metric tons; Broughton and sizes up to 2 cm
are commonly used in these tests. Materials can be or stratified with
neutralizing materials (for example, limestone) tc
Subaerial columns are used to simu||pPthe infiltration into and
drainage from materials that are exposed^^he of water may be
added to the column on a regular basi&Jrthe amypnt and added irregularly to
&£* JOjiirr j^^^? $1111?
simulate seasonal variability (Millsgrff 8c). ^peover, may be added to specific portions
of the column surface to promote|lipfalongjjpjferred p^pways, which allows oxidation
products to accumulate on parti^surfaces^^iin i^^&umn (Mills, 1998c).
3US COl
materis
be construe!
1998c). They"
a manner
,sed to infiltration into and drainage from
;ored cover. To simulate seepage to ground water, columns can
it of pore waters by supernatant water (Mills,
slow upward movement of deoxygenated water in
.armelBDosal.
'' {•? ^gii
Experiments del
rocl
1!
letermine the validity of column tests for tailings and waste
f_ples are summilzlfPIh Lapakko (1991; 1992). Several of these studies (e.g., Doepker,
concluded that oxidized more rapidly in columns that remained unsaturated between
ss, producing pH leachate than saturated columns. In general, column tests appear to
lish potenti^iPreactive materials from benign materials, but the leachant compositions
under natural settings (Doepker and O'Connor, 1990).
Shake Flask Extractions
Also termed batch reactor tests, shake flask tests utilize a split of powdered sample
immersed in distilled water that may be inoculated with bacteria. The flask is sealed and placed
on a shaker table where it is vibrated for a period of days to weeks. Samples are removed
C-19
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
periodically and analyzed to determine the sulfate content, pH and other water quality
parameters.
The shake flask test is relatively simple and inexpensive. However, for long duration
tests, water may need to be added to maintain volume and submersion of the sample may inhibit
oxidation of reactive sulfides (BC AMD Task Force, 1989). Interpretation of test results is quite
complex if water has been added periodically.
4.3.2.1.6 Field Tests
Field lysimeter tests are conducted using sample quantities
piles. The tests can be conducted for protracted periodsjjjlars)
In cases where samples have a small to moderate amo
durations are required to overcome the effects of neu
bacterial oxidation (Lapakko, 1991). Test piles are typ'.
impermeable liners to facilitate collection of drainage s
similar to actual or proposed waste rock or tailings pil
can be used to calculate the mass release rates of me
pped
4.3.2.2 Interpreting
. i'JJiJSC'fts*.* -•Vf~. "' 'tw^..*. *•"•'
Theint^lprelation of
can range frorrii&tively.strai
Mills, 1 998d).5!i|ll interpretations
test data, particle
A major advantage of field tests is thej
the disposal site, which provides more
generation and neutralization than benc
such as limestone addition (Humphrey^
it is critical that the tests be cond
short-term climatic variations.
use, especially for evaluating prJUosed ac
barrel-scale to.
^ ic conditions.
f neutralization
.onjjid the lag period tiaatprecedes
with lysimetefs or set atop
constructed in a manner
umes and concentrations
raste.
>
icntal conditions at
and the rates of acid
\ they allow control Options,
natural conditions. However,
lent length to smooth the effects of
on makes these tests difficult to
which accepted criteria are generally lacking,
o extremely difficult (Ferguson and Erickson, 1988;
d be based on knowledge of sample mineralogy, static
, and water flow (Mills, 1998d). Scaling issues are a
significant obstacle when usilench-scale kinetic test results to quantitatively estimate acid
generation in waste rock and tailings piles. Included are the effects of grain size and reactive
surface area, infiltration rates, and flushing rates and volumes (see comments in Hinners and
SAIC, 1993). J-
•,:. •»*'
WLqst investigators use temporal trends in leachate quality, including pH, sulfate, acidity,
alkalinity, and trace metals, to identify the progression of the acid mine drainage process (e.g.,
Ferguson and Erickson, 1988; Lapakko et al., 1995; Mills, 1998d). Because trends in leachate
composition reflect changing sample mineralogy and geochemical equilibrium conditions, they
must be interpreted cautiously. Equilibrium chemical speciation programs, such as MINTEQA2
(Section 5.2.2), can be used to identify the precipitation/dissolution reactions that are likely to
control leachate composition. It is important to keep in mind that lab-scale kinetic tests are
specifically designed to accelerate the natural weathering process. Consequently, these tests
C-20
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
cannot be used to determine when materials may begin to generate acid in the environment (only
that they will or will not), and they generally will produce leachates with higher metal
concentrations than would be produced naturally (Mills, 1998c). For most bench-scale tests,
samples are considered strongly acid generating if leachate pH falls below 3; acid generating with
some neutralization occurring if pH is between 3 and 5; and not significantly acid generating (or
generated acid is overwhelmed by excess alkalinity) if solution pH exceeds 5 (BC AMD Task
Force, 1989; Humphreys, 1990).
xfe»
,.jg,.. o
Sample mineralogy plays a pivotal role in controlling leachate quality (Mills, 1998d). For
samples lacking sulfate minerals, the production of aqueousjjulfate may be used to monitor the
sulfide oxidation process. In contrast, when gypsum or o^^bluble siife^ minerals are present,
their dissolution will provide aqueous sulfate that can mjjjjpsulfate produced by sulfide .^
oxidation. In some cases, high aqueous sulfate concengions produced by^gypsum dissolution
may delay the onset of sulfide oxidation in kinetic tes J"" " ™ x *~ "' '
from existing waste piles may contain previously form!
varying rates to contribute metals to kinetic test leachat
reduced pH. Depending on reaction kinetics, seconds
the effects of sulfide oxidation, which complicates call
1998d).
Whether kinetic test samples may
on the proportions of acid generating anjjjaeid neut
and reaction rates, and the particle sizejlnaracte
is a critical issue. Kinetic tests musJpiWcondi
the dissolution of neutralizing mj
lag-time that precedes the onset:
ae metal minii
x^ *w ' •* ^ ^
Test sansplEJ&eoliected
products that dissolve at
of these metals can lead to
ion is likely to overprint
>xidation rates (Mills,
pefjlbd of time
997)
gths
common
exampL
report
reported b;
more than two
results. Thi
liberatin^fedes enl
no
acidic leachates depends
their relative dissolution
aterials. Kinetic test duration
that is sufficient to permit
idation products and to overcome the
Ithough 20-week test lengths are
trend toward longer test times. For
durations of 40 weeks and Mills (1998c)
|xceed 104 weeks in western Canada. In long-term studies
ysamples did not begin to produce acidic drainage until
' Particle size also strongly influences kinetic test
'in many bench-scale tests enhance reactivity by
ilicate minerals (e.g., pyrite enclosed in quartz; Broughton and
998; Mills, 1998e). In coarser samples, these sulfides would
oreover, smaller particle diameters increase the total surface area
rexposed to oxidai
Id generating and jjjpid neutralizing minerals exposed to reaction which, in turn, affects
ton rates and quality (Lapakko et al., 1998; Mills, 1998c).
WW
[important to consider that differences between lab test conditions and the
Sfiient are likely to complicate extrapolation of kinetic test results. Differences
ambient atmospheric temperature, lab wetting cycles and natural precipitation
frequency, and complete flushing flows in the lab vs. incomplete or channelized flow in actual
waste piles are cited by Mills (1998c) as factors that require consideration.
4.3.2.3 State Recommendations
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
The states comprising EPA Region 10 presently have not promulgated formal guidelines
that cite specific kinetic procedures. The State of Nevada accepts kinetic testing methods that
include shake flask extractions, soxhlet extractions, conventional humidity cells, column tests,
and field tests (NV DEP, 1990). Although kinetic tests are required for samples of spent ore,
tailings, and waste rock, the State does not provide guidelines for the interpretation of test results.
The State of New Mexico recommends the use of humidity cells and columns for most kinetic
test applications, but will accept soxhlet extraction test results as appropriate (NMED, 1996).
The State recommends shake flask extractions for simulating closure conditionsjthat require
underwater storage (NMED, 1996). The State does not provide criteriaily^ vvhMf to interpret
kinetic test results. Applicants should check with state agencies to de||nM^whether they have
preferences that may not be codified.
4.3.3 Mathematical Models
Neither static nor kinetic test results provide the
unequivocally the potential for acid generation from
results must be extrapolated to longer time frames and;J
scaled to account for the differences in waste volumes^particle
distances, infiltration rates, flushing rates, and flusfc^^^lumes
and waste deposits. Mathematical models gapjpt'can help planners
determine the potential effects of waste
.data that determirlS^
tailings piles. Instead, test
tental conditions and
|cle separation
oratory test samples
Empirical models of acid gene
future conditions, typically using
1989). The accuracy of an empijjjiRnodeL
on the quality of the test data. Isllorsourc
distributions ibetween test;
x,,jj!*». _#|
conditioo|^|bey will waste <
in test results to extrapolate
data points (BC AMD Task Force,
ifinition a site-specific model, depends
ity include differences in particle-size
iterials and lack of model calibration to
retting (BC AMD Task Force, 1989).
;ls solve a series of equations that represent different
physical or cheim
-------
Mining Source Book
Uncertainty is introduced into theoretical models by an incomplete understanding of the
system which is being modeled or through use of simplifying assumptions (BC AMD Task
Force, 1989). In general, theoretical models may fail to properly describe fluid transport through
constructed waste piles, accurately predict thermal gradients that may arise due to the oxidation
process, and correctly determine the transport of oxygen and reaction products in compositionally
and physically heterogeneous wastes (BC AMD Task Force, 1989; Nicholson, 1992).
4.4 Leaching Procedures
Spent ore, waste rock, or tailings materials that are exposed to
potentially contribute metals or other contaminants to the environment,
from geological materials even under neutral conditions, but it is accel
generate acid as a consequence of sulfide oxidation. Co^sequently/a-variety
used to determine which constituents in waste materiafe^|.po^^ially mobile
expected environmental conditions.
jean
•onment can
be leached^
Lerials that „*
-'••if
tests are
4.4.1 U.S. EPA Procedures
EPA has developed three leach test procej
Leaching Procedure (SPLP) test and Toxicity.^
the most widely applied by the mining indjjSSr Thl
removal from mining wastes and materi?
4.4.1.1 EP Toxicity Test
The Extraction Proced
determine Whether a parti
ic Precipitation
icedure (TCLP) test are
applicable to metals
Theme
U.S. E
revision 1.
Solid samples
an extraction
ratio of egpletion fl
Jjpr
Follo^Kg extraction,
A Method 131OA) was developed to
the characteristics of a hazardous waste.
test for regulatory purposes, is outlined in
:nt version of the experimental procedure dated July 1992,
in fluid composed of acetic acid diluted to pH 5.0 ± 0.2.
to sizes smaller than 9.5 mm and placed into
roceu are used for mixed solid/liquid waste. A 16:1 weight
)lid is added to the bottle, which is agitated for 24 hours.
is filtered and analyzed for metals.
Toxicity Charaperistic Leaching Procedure Test
w
Siaracteristic Leaching Procedure (TCLP) Test (EPA Method 1311; ASTM
designed to evaluate the mobility of inorganic and organic constituents in
id mixed wastes in a sanitary landfill. The method is outlined in U.S. EPA
with the most recent version of the experimental procedure dated July 1992, revision 0.
For non-alkaline materials, the method uses an extraction fluid composed of acetic acid diluted to
pH 4.93 ± 0.05. For alkaline materials, the method uses an extraction fluid composed of acetic
acid diluted to pH 2.88 ± 0.05. Samples containing volatile organic components are leached
using a zero head space tumbler and the pH 4.93 extract fluid. For non-volatile materials,
samples of approximately 100 g are crushed to sizes smaller than 9.5 mm and placed into an
C-23
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
extraction bottle. A 20:1 weight ratio of extraction fluid:sample solid is added to the bottle,
which is agitated for 18 ± 2 hours. Following extraction, the leachate is filtered, preserved with
nitric acid, and analyzed for metals.
4.4.1.3 Synthetic Precipitation Leaching Procedure Test
The Synthetic Precipitation Leaching Procedure (SPLP) test (EPA MethodJ.312) was
designed to determine the mobility of organic and inorganic analytes in liquids, solids, and mixed
wastes using a a batch leach technique. The method is outlined in U.S. EPA (1986a), with the
most recent version of the experimental procedure dated September 1994.; lesion 0. For areas
west of the Mississippi River, the method uses an extraction, fluid composed of a 60/40 weight^
percent mix of sulfuric/nitric acid diluted to pH 5.00 ± Okf§ to sir
precipitation. Samples containing cyanide or volatile organic components;
special procedures and distilled water as the extraction!
of approximately 100 g are crushed to sizes smaller
bottle. A 20:1 weight ratio of extraction fluid:sample
agitated for 18 ± 2 hours. Following extraction, the lej
acid, and analyzed for metals.
4.4.1.4 Monofilled Waste Extraction Proc
extraction fr
allow single
by the
4.4.2 j; * State Procedure^
on-volatile
placed into;
to the bottle, which is
preserved with nitric
The Monofilled Waste Extractio:
developed to predict the composition
conditions. The procedure is out!
a 9.5 mm sieve and are combim
is tumbled at room temper;
extraction fluid, however.
fluids tha|i^pr>at a si
residue'fs^felEmdd to the
quential batch extraction test
waste under field
Solid materials are crushed to pass
10:1 liquid:solid ratio. The mixture
lure uses reagent grade water as the
ing process waters, ground waters, or other
leachate is filtered and analyzed. The solid
essel and the leach process is conducted using fresh
are recommended. Not only does this procedure
vely, but it permits more than one sample to be leached
|p The State of Nevada recently developed a leach test specifically for mining wastes. The
procedure has been broadly accepted by the mining industry and is being used to test wastes that
would be disposed of in other regions.
4.4.2,1 State of Nevada Meteoric Water Mobility Procedure
The State of Nevada uses a single-pass column leach test termed the Meteoric Water
Mobility Procedure (MWMP) to determine the potential for waste rock, spent ore, and tailings to
release certain constituents to the environment. The test is required by guidance documents
issued by the Division of Environmental Protection (NV DEP, 1990; 1996). The procedure is
C-24
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
provided in NV DEP (1996) and available (as of February 1999) on the internet
(www.enviromine.com/ard/Acid-Base%20Accounting/metal_leaching.htm).
The MWMP test uses 5 kg of material crushed to particle sizes smaller than 5 cm which
is loaded into an extraction column. A volume of extraction fluid equal to the dry weight of the
sample (milliliters of fluid equal to grams of sample) is passed through the sample in a 24 hour
period. Although the procedure states that the pH of the extraction fluid should "reflect the pH
of precipitation in the geographic region in which the mine rock is being evaluated/the
procedure uses Type II reagent grade water (distilled or deionized as pr|ljiced:byfMethod 1080
in APHA et al., 1992) as the extraction fluid. The pH valuesmf the i
homogenized leachate at the end of testing are recorded. jflli&mog^1
and analyzed for dissolved constituents.
4.4.3 Other Leaching Procedures
'^
Leach test procedures also have been developed'
U.S. Army Corps of Engineers, and the American Sock
These tests are not widely used by the American minirifg ind
4.4.3.1 British Columbia Procedures
The British Columbia Special
extraction that uses an acetic acid lixi
of 24 hours. According to Mills (
practice to used distilled water o:
ratio of 3:1, and an extraction ti
4.4.3.2 U
' '** H
"Me^hate and
'";-£*^\£-•*>£-, • •
IfiSchate is filtered
|nce of British Columbia, the
id Materials (ASTM).
WEP) is a single batch
s ratio, and an extraction time
British Columbia, it is standard
the extract fluid, a liquidrsolid mass
The1
"
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Myers and Brannon (1988) and Myers et al. (1991) describe a procedure developed by the
U.S. Army Corps of Engineers for column leach testing of dredged freshwater sediments. These
tests are recommended to confirm the results of sequential batch leaching tests and can be used if
the potential for contamination is high. The Myers et al. (1991) procedure uses an improved
column design that increases the number of pore volumes that can be eluted in a given period of
time by using a decreased column length and increased column diameter (producing pore water
velocities of approximately 10"5 cm/sec). The test, which uses kilogram samples, is conducted
using deoxygenated water as the leaching medium.
Graded serial batch tests are described by Houle andJ^png (1^
solid waste is mixed with an extraction fluid in a liquid :so|M|litio of I
intermittently for 24 hours. The sample is filtered and t||ieachate
material returned the extraction vessel for subsequent lejiching.
for each succeeding extraction (i.e., 4:1, 8:1,16:1, of seven
recommended for each sample. The extraction fluid water or any site-specific
fluid, thus permitting a determination of the constituents^^^^sie removed from or adsorbed
by the solid waste.
4.4.3.3 ASTM Procedures
The American Society for Testing njflnodologies for conducting
shake flask extractions (ASTM Method 03%7) of solid wastes
(ASTM Methods D4793 and D5284) (ASTM, 1996). liquid:solid mass ratios of
20:1 and extraction times of 18 hours/In the sequential tests, 10 leachate samples are
produced from a single solid wasffl^iniple. ^Methods D||p87 and D4793 use water for the
extraction fluid whereas memodjlp284 usj^^^acid^^ptraction fluid with a pH similar to that
of the average regional
4.4.4 State Recommen
that
Nevada Meteoric Wai
ore and
Mexico (NMED,
10 presently have not promulgated formal guidelines
leacllpl; procedure. The State of Nevada recommends use of the
ify Procedure to test representative samples of waste rock, spent
to release contaminants (NV DEP, 1996). The State of New
.ends use of EPA method 1312 (SPLP test) to test samples for the
potential to release con|8tninants. Applicants should check with state agencies to determine
whether they have preferences that may not be codified.
4.4.5 Comparison of Leaching Procedures
Batch leach tests vary significantly in their ability to extract metals from solid materials
depending on the type of extraction fluid employed. EPA Method 1312 (SPLP) is best suited to
mining wastes because it utilizes strong acids similar to those that would be generated under
oxidizing conditions. However, the SPLP test uses a combination of sulfuric and nitric acids as
the extraction fluid, which precludes determination of sulfate and nitrate concentrations in test
leachates. Because these constituents may be of interest (sulfates as oxidation products of
C-26
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
sulfides or hydrolysis products of acid-sulfate minerals; nitrates as blasting residue), it may be
practical to modify the procedure to substitute a strong acid such as hydrochloric acid, which has
similar, albeit less oxidizing, qualities, as the extraction fluid. The SPLP test also can be
modified to be more aggressive by decreasing the pH of the extraction fluid. The SPLP test is run
under conditions of high fluid to solid ratio (20:1) and short duration (18 hours), which limits the
extent to which biological oxidation will breakdown reactive sulfide minerals.
_^.
Sequential leach tests provide data regarding the rate at which constituents fcould be
released to the environment. In particular, these tests can show whether the concentrations of
metals in a leachate exhibit temporal trends. However, extrapolating Ael>s of sequential
leach tests to the expected conditions of waste disposal maykot be straigldfeward since most <;
tests are conducted on material that may have significantly" different reaetlcgi Mastics than the. J
actual waste (due to particle size) and because extraction durations and the amount of time „
between extractions do not replicate either natural wet-drjr cycles or conditions of atmospheric
oxidation.- " v
*f < ' . ," •» »,
Many leaching tests use reagent-grade water as/the extraetfolMuid, which may not
simulate the expected natural conditions, for example,' where acidffibilpa, occurs at depth in a
waste pile. To more closely approximate leachir^^Se^ions where^^^gi is acidic, reagent
water can be acidified using strong acids to of the reipnal precipitation. A
more acidic extraction fluid makes consequently, their
results provide a more conservative of mining materials on
water quality.
A recent study by Doyle jMtl 998;
(SPLP) and continuous column^p;edure:
metals leacbtirility than ibdfefellBffl tests
a more e:
, better
which te
5.0 AN|
ilyzing ch
intentions between th
Duntas, 1983).
: (soil, atmosp
Anderson
ached sajiples of mining wastes using batch
|ey fop^that batch tests tended to predict higher
fys), suggesting that they typically provide
vironmengppenavior. However, the study did not indicate
actual field conditions.
JSPORT
tid transport at mine sites is a complex task due to the
anc
.Hogic cycle, pollutant cycle, and sedimentation (watershed) cycle
fnsequently, fate modeling includes processes that occur on the land
, and water), the unsaturated zone, and the saturated zone (Bonazountas,
_ .oessner (1992) describe a modeling protocol for ground water systems
^.^ and applied to mine sites. It includes establishing the purpose of the model,
eoficeptual model, selecting governing equations and an appropriate computer code,
, verifying and calibrating a numerical model.
5.1 Developing a Conceptual Model
A conceptual model is a pictoral representation of a complex system, frequently in the
form of a block diagram or cross-section (Anderson and Woessner, 1992). The conceptual
C-27
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
model simplifies a complex field problem and makes it more amenable to modeling. In
particular, it helps to determine the dimensions of the numerical model and the design of an
appropriate grid. An example of a conceptual physical ground water model taken from Anderson
and Woessner (1992) is shown in Figure C-l. A conceptual physicochemical model of metal
transport in a river, taken from Schnoor (1996), is shown in Figure C-2.
Four information components are needed to develop a conceptual site modej (Bedient et
al., 1994). Geology provides the physical framework within which subsurface fljpfe collect and
flow and an understanding of the characteristics of the materials and sqMy^a^fthat must be
handled. Hydrology describes the movement of fluids across; the the
physical framework (subsurface). Chemistry defines the nlpi of th
transported by the surface and subsurface flow systems,J|puding as
apply to fluid chemistry. Climate provides data to desdllle interactions
evaporation, surface flow, subsurface flow, and infiltra
The amount of data required to develop a mine
transport are considerable (Schnoor, 1996; Hemond
mine plan provides information about the locations, c
wastes, surface and subsurface disturbances,
and outfall locations and discharges. The
material that will be excavated, processed
effects of climatic variations, drawdown^
Surface water
hydrology provides information rejgiirflfng di
chemistry, and storm runoff. Grjjw^water
gradients, ground water volunieSKround
data on vertical stratigrapi
•-"*'-' "
o:
chemical a
Contaminant c
model of fate and
•U.S. EPA, 1989). The
s of materials and
water diversions,
bunt and character of
ance characterizes the
waste water discharge.
ics desi
physical stabil|^;cpiiifi§§ad.liquiliilistes and materials.
5.2 "Mathematical
r seasonal variation, surface water
ribes flow rates (flux), hydrologic
, and flow paths. Geology provides
.1 changes in stratigraphic relations, the
ilneralogy. Aquifer characteristics include
iductivity, porosity, and fracture and matrix flow and
neutralizing components and biogeochemical processes.
lemistry, density, discharge, volume, and chemical and
Mathematical m|»aels that couple physical flow and chemical mass balance equations are
simulate the flow and transport of contaminants through the environment. Because
models used for predictive purposes are only as good as the data input to them, high quality, site-
specific data are required to produce confident and realistic model predictions.
5.2.1 Categories of Mathematical Models
Mathematical models can be grouped into three general categories (Knox et al., 1993).
Analytical models solve governing equations using simplifying assumptions. They are generally
one- or two-dimensional models that assume steady-state flow. Stochastic models incorporate
uncertainty by using mean values coupled with a measure of variance. Numerical models, which
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
GEOLOGIC UNITS IN
HYDROGEOLOGIC FRAMEWORK
reET " Pleistocene/ Pleistocene sands and
Holocene sands Hawthorn Formation
HYDROGEOLOGIC
UNITS IN
CONCEPTUAL
MODEL
Lower Florldan
aquifer
Freshwater-saltwater
Interlace
EQUIVALENT UNITS IN
DIGITAL GROUND-WATER
FLOW MODEL
Recharge/discharge at surface
translated Into source-bed leakage
to/from Upper Florldan aquifer and
discharge to springs or streams via
head-dependent source-sinks
-3600
VERTICAL SCALE GREATLY
EXAGGERATED
0 10 20 30 MILES
0 10 20 30 KILOMETERS
Missing Impermeable boundary
° (Lower confining unit
mi
u "
Figure C-l. Conceptual physical niodeL
(1992).
are the most commonly used mcgHprrn,
equations of flow and mass equatij
in one-, twgJ|pr using
etal. (^andBedient
or freshwater-
saltwater Interface)
.derson and Woessner
r
brnputedlpiiutions to coupled partial differential
if con^pnant fate. Numerical models are solved
.ement, finite difference, or method of
each of these methods can be found in Knox
C-29
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Diffusion
_». to deep
sediments
Figure C-2. Conceptual physicochemical model of metal transport in a river from Schnoor
(1996).
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
5.2.2 Chemical Equilibrium Models
Numerous physical, chemical, and biological processes occurring in surface and
subsurface environments can affect the transport and fate of contaminants. These can be divided
into abiotic and biotic processes (Keely, 1989a). Abiotic processes are physical and chemical
interactions that cause contaminants to move at a rate different from than that of surface or
ground water. They include hydrolysis, sorption, cosolvation, immiscibility, ionization,
radionuclide decay, complexation, volatilization, photodegradation, precjpitationspssolution,
and reduction-oxidation (Johnson et al.51989; Schnoor, 1996). Biotic j^cessۤare microbially
mediated transformations or adsorbtion of contaminants. Thf^ includ^i^l^^dation and
bioaccumulation. Other physical processes that may affeei|pitaminli^ii|Krations include.*,
hydrodynamic dispersion, molecular diffusion, and densli'stratificatictti"
i'IK7' •'*•&
Chemical equilibrium models calculate change
equilibrium. Aqueous models of trace metal concentra
accounting for aqueous-phase complexation (e.g., by na
complexation (e.g., by ion-exchange on the surfaces o
particles (e.g., lead adsorbed on the surface of ferric hi
hydroxide), mineral dissolution (e.g., calcite dis
the formation of colloidal suspensions by e
solubility (e.g., Cr+3 and Cr+6), and adsorptiirey so
1996), Summary descriptions of three
MINTEQA2, are given in Schnoor (19
5.2.3 Physical Flow and Tra
Flo
(saturate
withom
and
sitejJBrtheU.S.EPA'
>ute chemical specilsrby
ing humic acids), surface
and sedimentation by
jecipitation (e.g., ferric
>n/flocculation (e.g.,
;ses), reBlpl^actions that affect
Johnjfen et al., 1989; Schnoor,
; MacjiQL, MINEQL+, and
•ailable for surface water, ground water
zone). They typically are used in conjunction
^models described above. The mathematical development
itions used in many of these models is given in Schnoor
of the gove:
(1996).
compute river water quality include QUAL2EU, NONEQUI,
s are given in Schnoor, 1996 and are available via the internet n
S. Kerr Environmental Research Lab and Center for Exposure
sment Modeling)JIQUAL2EU is a steady-state model for pollutants in branching streams
veil-mixed lakesjplt incorporates uncertainty analysis into the model results.
points out that many ground water models are inappropriate for use in
face flow is controlled by fractures or karst features. Consequently, the choice
of mi^rermines whether realistic model predictions can be computed for these areas.
Bedient et al. (1994) provide summary model descriptions and a listing of modeled processes for
a variety of unsaturated and saturated flow and solute transport models. Included are 6 vadose-
zone flow models, 11 vadose-zone solute transport models, 12 saturated zone flow models, and 9
saturated zone solute transport models. Additional model descriptions are available via the
internet from the U.S. EPA's Robert S. Kerr Environmental Research Lab. Among the more
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
widely used saturated zone models are MODFLOW, a three-dimensional finite difference model,
and USGS-MOC, a two-dimensional finite difference and methods of characteristics model for
ground water flow and solute transport. Anderson and Woessner (1992) describe three
conceptual models that can be used to approximate flow through a fractured system for input to
models based on saturated or unsaturated flow. Each of these conceptual models uses
assumptions that oversimplify flow through the fractured system.
6.0 SAMPLING PROGRAMS
The environmental sampling process should folio
collected samples are representative and adequate (Triegj
the goals of the sampling program and the levels of co:
samples then can be determined by characterizing the
heterogeneity). Using these data, the sample program
consider the types of analyses that will be conducted on
distribution of samples and their manner of collection.,
address geochemical testing programs.
6.1 Objectives of a Geochemical Sampl
Establishing a reliable geochemi
mine site development. By indicating^ifnether
methods should be added to the mine
samples can diminish, perhaps th
wl&iiiiiiijf
would be encumbered should en0Fonmeni
Broughtony ,19 92).
lability (e.j
The
and include the number and
lions specifically
Tlie geologic histc
"> -Gir* ' /., i,,. -^m
?•
cult, but critical, aspect of
or alternative disposal
program that uses representative
ination mitigation and control that
se in the future (Robertson and
particular IdeaftanifAs a resul
Nevertheless, afeanipi^ progrs|a§
jre of mineralization observed at a mine site is unique to that
ical sampling programs will differ from site to site.
d strive to capture the range of variability that occurs,
provide an aecfir^e statistical repres^tation of the materials present, and objectively test the
feasibility of the disposa^meinods described by the proposed mine plan. A geochemical
sampling program should consider several factors that could affect the chemical or physical
character of samples and, consequently, impact test results. Included are the method of sample
collection, the length of time that a sample will be (or has been) stored prior to analysis, and the
environment in which samples are (or were) stored (U.S. EPA, 1994).
For proposed mines, sampling and testing programs use fresh samples to predict the
potential for acid generating conditions to develop or metals to leach from materials and wastes
(Robertson and Broughton, 1992). A sampling program should be related directly to a mine plan
that outlines the area to be mined, the locations of pit walls and benches or underground
workings, the locations and amounts of ore and waste rock that will be excavated, and the
approximate timing of excavation and final placement of the materials (BC AMD Task Force,
1989). The latter is especially important for determining the potential for contaminant release
from waste rock dumps because these features can vary in particle size, particle mineralogy, and
C-32
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
chemical composition over short distances. The sampling program also should include materials
produced during bench-scale or pilot-scale processing tests conducted on samples that encompass
the range of materials that will be processed over the life of the operation. Geochemical and
mineralogical variability can be evaluated using three-dimensional geostatistical techniques
similar to those used to describe the ore body (Robertson and Broughton, 1992).
Sampling and testing programs at existing or abandoned mines should address questions
regarding the quantity of acid products stored in the materials and wastes and howjiontamination
emanating from them is likely to change in the future (Robertson and B)||ight0Bfi992). For
studies of existing waste rock dumps, spent ore heaps, or tailings pile^||iap§iing program must
establish the physical, mineralogical, and chemical variabjfipo'f the milflplfeand wastes (see
Nash etal., 1998).
6.2 Sample Representativeness
Samples used in geochemical tests should be rep:
mined and processed. According to Smith et al. (1988!
to which data accurately and precisely represent a characteristi
variations at a sampling point, or a process or en^o^iBfental con
of uncertainty in a sampling and testing progrj
the question of how accurately a sample rejjjlients i
addressed by establishing the variation i|plrent inj
samples and examining their frequencyjpstributjjp (BC
6.2.1 Proposed Mine Sites
I.
each li
They
possible,
initial tests c
attributes
o determine
ittha
their
of the materials that will be
£ss expresses the degree
.ation, parameter
teed, the major source
pies t&epselves. In particular,
ie.0f material can only be
rock unit by taking multiple
Force, 1990).
and should be conducted initially on
otherwise disrupted in a mine site area.
jineralogical zonation observed within the ore body and, if
it separates ore material from waste rock. The results of
similar geochemical and leachate production
rodie et al., 1991). In some cases, test results will
tglogic unit be divided into two or more geochemical rock units,
>re homogeneous lithologic units may be grouped together.
lould be tested further to define the range of its geochemical
;, a sampling program uses an iterative process to assess variability and
designed sufficiently flexible to respond to changes in the mining plan
iton, 1992).
IF
,^__ Jfical test samples should be collected from each geochemical rock unit over the
fSnd areal extent of the mine site or area of interest. Geographical representativeness
can be depicted using maps and cross-sections. The number of samples that should be tested
depends on the volume and variability of the rock unit in question. In general, sample
requirements increase with chemical and mineralogical heterogeneity. As a general guide for
acid-base accounting tests, the BC AMD Task Force (1989) recommended a minimum number
of samples appropriate for a rock unit with a given mass (Figure C-3). This approach can lead to
C-33
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
extensive sampling requirements for large facilities and result in inordinately high sampling
costs.
As an alternative, Runnells et al. (1997) suggested that the number of required samples should
reflect the heterogeneity of the materials within the facility. The appropriate number of samples
is obtained when statistical variability in sample results is within acceptable limits. Using this
approach, the number of samples needed to characterize a facility will vary from one facility to
another because each facility is unique. The Runnells et al. (1997) method can be applied easily
to existing facilities, but may be difficult to apply to materials that would be disrecl of in
proposed facilities. Nevertheless, sampling programs that use a fi
approach should be designed to ensure that sample variability can be»with statistical
validity (e.g., BC AMD Task Force, 1990).
Geologic materials, which are composed of onej| more
composite materials. For the purposes
enough to smooth the effects of small-scale heterogene
variations present in the rock unit of interest. The effects
distribution of net neutralization potential values obtaii
described by Robertson and Broughton (1992). For waste roc*
samples are commonly lengths of drill core or
suggest restricting drill core lengths to less th<
ensure that the chemical behavior of a was
iple sizes;
1 enough to reviaptne
ite sample size on the
variable rock mass are
den materials,
Broughton (1992)
.ccounting tests to
on small and large scales.
C-34
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
RECOMVBjDED!
SAMPLE NUVBERS
8107 2 46 8108 2 46 8109 2 4
Figure C-3. Recommended minimum number of samples as a function of rock mass (BC AMD
Task Force, 1989).
C-35
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
6.2.2 Existing or Abandoned Mine Sites
Existing or abandoned mine sites can pose special problems for geochemical test
sampling because the history of the mine and the detailed composition of materials and wastes
may be unknown or unrecorded. Changes to processing methods and efficiency that may have
occurred during active production or time gaps when mining did not occur can produce chemical
and physical heterogeneity within piles of materials that are not evident from their exposed
surfaces. Consequently, sampling programs designed for existing or abandonedjjpne sites
should determine the variability of all materials disposed of or exposed^Mie^iflace (see
discussion of Runnells et al. 1997 in Section 6.2.1 and Nash/et al., walls, this will
require collecting samples vertically and laterally across waste rock-
dumps, spent ore heaps, and tailings impoundments, it ||fcequire lateral!
and vertically throughout the deposit (typically by drilli||) (Nash <
from these samples can be used to construct a three-dir^^ionajpriage of the
chemical and physical character of the waste in the previoHRSction, the
number of samples required by the program depends on
materials in question, but generally increases with chej
heterogeneity.
and
variability of the
, and physical
6.3 Quality Control and Quality Assui
A recent report by Downing andjpls (19SJP dS
assurance and quality control procedurJfas they aipply to
guidance and procedures prepared JpnEfPA are/ayailable i
QA website (www.epa.gov/rl Oea^feffices/^
of QAPP documents is in reviewed is set
ipplication of quality
k drainage studies. QA/QC
dobe format on the EPA Region 10
qamde^Hm). New guidance for the preparation
ed foiiislue in early 1999.
6.3.1 Quality Contr
measurement
specificatioi
sample containers.
id star®
|trol as the application of good lab practices, good
bdures for sampling. The latter should include
age and preservation, stabilization methods, labeling, and
, . . .
;? Physical and geocneiMcal tests conducted using approved methods (EPA or otherwise)
will produce analyticaLresults with accuracy and precision sufficient for all likely applications,
providing that methods%re chosen for their ability to meet the data quality objectives described
iiiithe^next section. Jta this regard, it is important for applicants to select analytical methods that
have the necessary detection limits. Applicants should periodically submit replicate samples for
testing and analysis to confirm laboratory assessments of analytical performance.
6.3.2 Quality Assurance
Quality assurance is the process of monitoring for adherence to quality control protocols
(Taylor, 1988). Smith et al. (1988) list five data quality objectives of a quality assurance project
plan (QAPP): precision, bias, representativeness, completeness, and comparability (cf. U.S. EPA,
C-36
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
1980; 1998a; 1998b). Precision leads to a measurement of variance (e.g., standard deviation) and
is the mutual agreement among individual measurements under prescribed similar conditions.
Bias refers to the degree to which a measurement reflects an accepted true or reference value,
commonly expressed as a percentage. Representativeness, as described above, expresses the
degree to which data accurately represent a characteristic of a population. Completeness is a
measure of the amount of valid data compared to the amount expected to be obtained under
normal conditions. Comparability is a measure of confidence that one data set can be compared
to another. -'
A QAPP will ensure that procedures are established prior to
collection and will help to balance the costs of implem< ' "**;;Esi"
the liabilities of a poorly designed and executed sampli
7.0 REFERENCES
American Public Health Association, American Waterjpfr.
Environment Federation (APHA et al.), 1992. lltandar,
Waters and Waste-waters, 18th edition,
D.C..
Anderson, M.P. and Woessner, W.W., 1
Flow andAdvective Transport^ifcademit
against^
*
ASTM, 1996, Annual Book of Al
Philadelphia, PA.
ion, and Water
the Examination of
iation, Washington,
Modeling: Simulation of
iego, CA, 381 pp.
ASTM,.
inal
liladel
BC AMD Tasl
Colui
89. Iff
fen, Norel
r *"'WW
Standards, American Society for Testing and Materials,
IM Standoms/vol. 11.04, American Society for Testing and
3.259-271.
%ock Drainage Technical Guide, Volume 1, British
_ Task Force Report prepared by Steffen Robertson and
lental Consultants, and Gormely Process Engineering, August
m /jit tw
rMD Task Force, J&90 Monitoring Acid Mine Drainage, British Columbia Acid Mine
I Drainage TaskSForce Report prepared by E. Robertson in association with Steffen
& Robertson aa^Kirsten, Inc., BiTech Publishers, Ltd., Vancouver, B.C., 66 pp.
_^__i, H.S., and Newell, C.J., 1994. Groundwater Contamination: Transport and
^Oimediation, PTR Prentice-Hall, Inc., Englewood Cliffs, NJ, 542 pp.
Berlin, E.P., 1970. Principles and Practice of X-Ray Spectrometric Analysis, Plenum Press, NY,
' 679 pp.
C-37
-------
Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Bish, D.L. and Post, I.E., eds., 1989. Modern Powder Diffraction, Reviews in Mineralogy,
Volume 20, Mineralogical Society of America, Washington, D.C., 369 pp.
Blatt, H., Middleton, G., and Murray, R., 1980. Origin of Sedimentary Rocks, 2nd ed., Prentice-
Hall, Englewood Cliffs, NJ, 782 pp.
Bonazountas, M., 1983. Soil and Groundwater Fate Modeling. In: Swarm, R.L. and
Eschenroeder, A., eds., Fate of Chemicals in the Environment, AjCS Symposium Series
225, American Chemical Society, Washington, D.C., p. 41-65.
Bradham, W.S. and Caruccio, FT., 1990. A Comparativejlply of
Acid/Base Accounting, Cells, Columns, and Soxjfpts, Proce*
and Reclamation Conference and Exhibition, Cleston, W|V^ p. 19-2,5. 'rj*
Brady, K.B.C., Smith, M.W., Beam, R.L., and Cravo
Addition of Alkaline Materials at Surface Coal
Mine Drainage: Part 1 & 2, Proceedings oj
and Exhibition, Volume 1.
Brannon, J.M., Myers, T.E., and Tardy, B.A.
Freshwater Sediments, U.S. Army^
Miscellaneous Paper D-94-1,64 j
Brodie, M.J., Broughton, L.M.,
System for Waste Mana
Using *
1990. Effectiveness of the
^venting or Abating Acid
Reclamation Conference
Evaluation for
tys Experiment Station,
Piles. In: Proceedings
Acidic Drainage,
A Conceptual Rock Classification
ethod for ARD Prediction from Rock
Conference on the Abatement of
19-136.
., 1992. Acid Rock Drainage from Mines - Where We Are
ternational Corporation, Predicting Acid Generation
of July 1992 Workshop, Draft report prepared for
ystems Laboratory, Office of Research and Development,
UJS^nvironrniittiil^ection Agency, Las Vegas, NV.
..••& ~f '"Li v'i-iriia-ft^j^^yiV;^.
^g •T' •/'.#''•& fri-:??"^'- • /
Bruynesteyn, A. and Hapklf;R.P., 1984. Evaluation of Acid Production Potential of Mining
s Waste MaterialsJeMmera/s and the Environment, vol. 4, p. 5-8.
Carson, C.D., Fanning, D.S., and Dixon, J.B., 1982. Alfisols and Ultisols with Acid Sulfate
Weathering Features in Texas. In: Kittrick, J.A., Fanning, D.S., and Hossner, L.R., eds.,
Acid Sulfate Weathering, SSSA Special Publication No. 10, Soil Science Society of
America, Madison, WI, pp. 127-146.
Caruccio, F.T., Perm, J.C., Home, J., Geidel, G., and Baganz, B., 1977. Paleoenvironment of
Coal and its Relation to Drainage Quality, U.S. Environmental Protection Agency
Report EPA 600/7-77-067, 118 p.
C-38
-------
Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Coastech Research, 1989. Investigation of Prediction Techniques for Acid Mine Drainage,
MEND Project 1.16. La, Canada Centre for Mineral and Energy Technology, Energy
Mines and Resources Canada, 61 pp. plus appendices.
Craig, J.R. and Vaughn, D.J., 1994. Ore Microscopy and Ore Petrography, 2nd ed., John Wiley
and Sons, NY, 434 pp.
Davis, G.B. and Ritchey, A.I.M., 1986. A Model of Pyrite Oxidation inPyritic Mine Wastes:
Part 1, Equations and Approximate Solution, Applied Mathematical Modeling, vol. 10,
pp. 314-322. ****.***
Deer, W.H., Howie, R.A., and Zussman, J., 1992. An
Minerals, John Wiley & Sons, New York, NY.
Doepker, R.D., 1989. Enhanced Heavy Metal Mobili
AIME Preprint No. 89-104, 1989 SME Annual
Doepker, R.D. and O'Connor, W.K., 1990. Column
Characteristics from Selected Copper Mi
Rehabilitation, and Treatment ofDisti
Downing, B.W. and Mills, C., 1998. QuftyAssumncl _
Studies, Report posted on the Ewiromin^porldwide website,
http://www.enviromine.con^^B'Acid-^^e%20A^ounting/Quality .htm, viewed
10/14/98.
Doyle, T,
^^Vp'w** - ™*
Unsaturated MinPFiflings,
Vegas, NV, 7 pp.
[etal Dissolution
^Planning,
990,13 pp.
Control for Acid Rock Drainage
; D.D., 1998. A Comparison of Batch and
fSociety for Mining, Metallurgy, and
Duncan, D.
Mai
Ferg
! Determination of Acid Production Potential of Waste
AIME Paper A-79-29, 10pp.
.,1988. Pre-Mine Prediction of Acid Mine Drainage. In:
icr, U., eds., Environmental Management of Solid Waste,
IY, pp. 24-43.
;dman, L.C., 1989. Methods for Determination of Inorganic Substances in
luvial Sediments, Techniques of Water Resources Investigations of the U.S.
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Goldhaber, M.B., 1983. Experimental Study of the Metastable Sulphur Oxy-Anion Formation
during Pyrite Oxidation at pH 6-9 and 30°C, American Journal of Science, vol. 283,
pp. 193-217.
C-39
-------
Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Goldstein, J.I., Newbury, D.E., Echlin, P., Joy, D.C., Fiori, C., and Lifshin, E., 1981. Scanning
Electron Microscopy andX-Ray Microanalysis, Plenum Press, NY, 673 pp.
Gobble, C.D. and Hall, A.J., 1993. Optical Mineralogy: Principles and Practice, Chapman and
Hall, NY, 302 pp.
Harris, D.C., 1987. Quantitative Chemical Analysis, 2nd edition, W.H. Freeman and Company,
New York, 818pp.
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Academic Press, San Diego, CA, 338 pp.
Hirmers, T.A. and Science Applications International Corporation (S.
Acid Generation from Non-Coal Mining WastestjjJotes ofgjjlSfy,
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U.S. Environmental Protection Agency, Las vdjttBHEPA/600/R-93/i
Houle, M.J. and Long, D.E., 1978. Accelerated Testi
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Proceedings of the Fourth Annual Researj
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Houle, M.J. and Long, D.E., 1980. Intej
Wastes and Soils. In: Shultz,'.
Sixth Annual Research Syn
600/9-80-010, March 60-8J
•osium,
152-1H
liability and Contaminant
•dous Wastes,
inmental Protection
atch Extraction Tests of
Wastes, Proceedings of the
ital Protection Agency, Report EPA-
Humphreys, R.D., 1990.
Com
Acid-Generation Potential Tests, Water
a, Report 90-18CWP, 19 pp.
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Environmental PipMt4n"Agency, Seminar Publication: Transport and Fate of
Contaminants MiHie^bsurface, Office of Technology Transfer, Report EPA 625/4-89-
019, pp. 41 -56.0
f
Johnson, W.M. andjMaxwell, J.A., 1981. Rock and Mineral Analysis, 2nd ed., John Wiley and
Sons, NY, 489 pp.
v ^ ^
Keely, J.F.; 1989a. Introduction. In: U.S. Environmental Protection Agency, Seminar
Publication: Transport and Fate of Contaminants in the Subsurface, Office of
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Environmental Protection Agency, Seminar Publication: Transport and Fate of
C-40
-------
Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Contaminants in the Subsurface, Office of Technology Transfer, Report EPA 625/4-89-
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Kerr, P.P., 1977. Optical Mineralogy, 4lh ed., McGraw-Hill, NY, 442 pp.
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Knox, R.C., Sabatini, D.A., and Canter, L.W., 1993. Subsurface Tranqjfat anafate Processes,
Lewis Publishers, Boca Raton, FL, 430 pp. ^^ **'
Lapakko, K., 1991. Mine Waste Drainage Quality Pre,
to the Minnesota Department of Natural Reso
Lapakko, K., 1992. Evaluation of Tests for Predicting
the Western Governors' Association, May 1992
Lapakko, K., 1994. Evaluation of Neutralization Pote
and a Proposed Alternative, Proceedings
Mine Drainage Conference, U.S. B
A LiterMi^ji^^v, Draft report
•te Drainage p/£ llllrf report to
Lapakko, K., Wessels, J., and Antonsonjjji; 1995.Mot
Waste, U.S. Environmental PrqfjlStion Ajspicy Rej
for Metal Mine Waste
'eclamation and
-94, pp. 129-137.
Wolution Testing of Mine
530-R-95-040, 85 pp.
Lapakko, K., Haub, J., and AntOjglfprD., EffectsMDissolution Time and Particle Size on
Kinetic Test Results, for Mej^prgy, and Exploration, Inc. Preprint, 98-
Lawrenc
Cl
Draindz
Assc
i of Mi
Meet!
Lawre
R.W. and
'Drainage Predk
procedures for the Prediction of Long Term Weathering
, Proceedings of the Symposium on Acid Mine
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?96. Determination of Neutralization Potential for Acid Rock
IEND Report 1.16.3, Ottawa, ON, 149 pp.
;nce, R.W. and Ifping, Y., 1997. Determination of Neutralization Potential in the
(cid Rock Drainage, Proceedings of the Fourth International Conference
-.Drainage, Vancouver,BC,pp. 15-30.
Jaffe, S., and Broughton, L.M., 1988. In-House Development of the Net Acid
Production Test Method, Coastech Research.
Lundgren, D.G. and Silver, M., 1980. Ore Leaching by Bacteria, Annual Review of
Microbiology, vol. 34, pp. 263-283.
C-41
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Miller, S., Robertson, A., and Donahue, T., 1997. Advances in Acid Drainage Prediction using
the Net Acid Generation (NAG) Test, Proceedings of the Fourth International
Conference on Acid Rock Drainage, Vancouver, BC, pp. 533-549.
Mills, C., 1998a. Acid-Base Accounting (ABA), Report posted on the Enviromine worldwide
web site, http://www.enviromine.com/ard/Acid-
Base%20Accounting/ABAdiscussion.htm, viewed 10/14/98. ,
Mills, C., 1998b. Acid-Base Accounting (ABA) Test Procedures, Report posted on the
Enviromine worldwide web site, http://www.envirornine.com/ard/Actd-
Base%20Accounting/acidbase.htm, viewed 10/14/98. * «f* ; -
Mills, C., 1998c. Kinetic Testwork Procedures, Repor^psted on tne^Envirbmime worldwide
website, http://www.enviromine.com/ard/Kine|.^20Te^s/kinetic%20pc(K»ittres.htrn,
viewed 10/14/98.
Mills, C., 1998d. Kinetic Testwork Interpretation, Repj^fpliiel^i§the Enviromine worldwide
• r f-:*' r "
-------
Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Nash, J.T., Desborough, G.A., and Fey, D.L., 1998. Geochemical and Mineralogical
Characterization of Mine Dumps on BLM Lands, Upper Animas River Watershed,
Colorado: Plans and Preliminary Results, Science for Watershed Decisions on Abandoned
Mine Lands: Review of Preliminary Results, Denver, Colorado, February 4-5, 1998, U.S.
Geological Survey Open-File Report 98-297, pp. 44-45.
Nevada Department of Environmental Protection (NV DEP), 1990. Waste Rock and Overburden
Evaluation, September 14,1990,2 pp. plus attachment.
Nevada Department of Environmental Protection (NV DEP^996.
Alternate Use of Mine Waste Solids - Disposal Oi^^
'
7pp.
New Mexico Environment Department (NMED), 1996
Mining Sites, Draft report by the Ground Waterf|
1996,10pp.
23, 1996,
* '"'-1
schajgi Plan Closit
Prevention SectH
Nicholson, R.V., 1992. A Review of Models to Predfcf Acid
Waste Rock at Mine Sites, International ofWa
29 to October 1, 1992, Toronto, Q
ates in Sulphide
^Modeling, September
Nicholson, R.V., Gillham, R.W., and Region, E.L
Buffered Solution: 2. Rate by Coatl
Acta, vol. 54, pp. 395-402.^W jf |,
?
cidation in Carbonate-
feochimica Cosmochimica et
li'
Norrish, K. and Chappell, B/W JJ|67. X-]
(ed.M>hysical
0'Shay,T.
Metho
Envi
., Miller, R.H
and Microbiolo
7luor.e|ilnce Spectrography. In: Zussman, J.
fralogy, Academic Press, London, pp. 161-
^ J.B., 1990. A Modified Hydrogen Peroxide Oxidation
itial Acidity in Pyritic Overburden, Journal of
Ifpp. 778-782.
cy, D.R., 1982. Methods of Soil Analysis: Part 2 - Chemical
iM?"
roperties, 2nd edition, American Society of Agronomy, Inc., Soil
Science Societyjft America, pp. 199-209.
||c, P., 1991. Jjihdbook of Environmental Analysis: Chemical Pollutants in Air, Water,
"md Wastes, CRC Lewis Publishers, Boca Raton, FL, 584 pp.
^.^., ^oitt, H.W., Gunter, W.D., St-Arnaud, L.C., and Mycroft, J.R., 1995. Critical
^Review of Geochemical Processes and Geochemical Models Adaptable for Prediction of
Acidic Drainage from Waste Rock, Mine Environment Neutral Drainage Program Report
1.42.1, Natural Resources Canada, Ottawa, ON, April 1995.
C-43
-------
Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Price, W.A., 1997. DRAFT Guidelines and Recommended Methods for the Prediction of Metal
Leaching and Acid Rock Drainage at Minesites in British Columbia, British Columbia
Ministry of Employment and Investment, Energy and Minerals Division, Smithers, BC,
143 pp.
Renton, J.J., Rhymer, A.M., and Stiller, A.H., 1988. A Laboratory Procedure to Evaluate the
Acid Producing Potential of Coal Associated Rocks, Mining Science and Ttjchnology, v.
7, pp. 227-235.
Robertson, A.M. and Broughton, L.M., 1992. Reliability oMcid R<
Science Applications International Corporation, Pj^^in,
Coal Mining Wastes: Notes of July 1992 Workshijfbraft
Environmental Monitoring Systems Laboratoryj|f ffice of Research
U.S. Environmental Protection Agency, Las
,299pp.
Robinson, J.W., 1990. Atomic Spectroscopy, Marcel
Runnells, D.D., Shields, M.J., and Jones, R.L., 1997.
Mill Tailings and Mine Waste Rock. In:
Rotterdam, pp. 561-563.
Schnoor, J.L., 1996. Environmental Moving:
and Soil, John Wiley and SonsjBc., Ne\
* ': ,?. a\n> * A
[equacy of Sampling of
7- Balkema,
if Pollutants in Water, Air,
SENES Consultants, Ltd. and
Generation by Bt
#15SQ.23241-5-
Assisstnent Pro
SENES
. Estimation of the Limits of Acid
rranium Mill Tailings, DSS File
for the National Uranium Tailings
wa, Ontario.
gultants, Ltd., 1988. Adaptation of the ReactiveAcid
TAP) to Base Metal Tailings —Appendices A-I,
ia Centre for Mineral and Energy Technology, EMR,
Sherlock, E.J., LawrencpRlpC, and Poulin, R., 1995. On the Neutralization of Acid Rock
Drainage by CaJbnate and Silicate Minerals, Environmental Geology, vol. 25, pp. 43-54.
Qttwa,
Skousen, J., Renton* J., Brown, H., Evans, P., Leavitt, B., Brady, K., Cohen, L., and
Ziemkiewicz, P., 1996. Effect of Digestion Method, Siderite Content, and Fizz Rating on
Neutralization Potential of Overburden Samples. In: Skousen, J. and Ziemkiewicz, P.,
eds., Acid Mine Drainage: Control and Treatment, 2nd Edition, pp. 47-68.
Skousen, J., Renton, J., Brown, H., Evans, P., Leavitt, B., Brady, K., Cohen, L., and
Ziemkiewicz, P., 1997. Neutralization Potential of Overburden Samples Containing
Siderite, Journal of Environmental Quality, vol. 26, pp. 673-681.
C-44
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
Smith, F., Kulkarni, S., Myers, L.E., and Messner, M.J., 1988. Evaluating and Presenting
Quality Assurance Sampling Data. In: Keith, L.H., ed., Principles of Environmental
Sampling, American Chemical Society, Salem, MA, pp. 157-170.
Smith, K.S., Plumlee, G.S., and Ficklin, W.H., 1994. Predicting Water Contamination from
Metal Mines and Mining Wastes: Notes, Workshop No. 2, International Land
Reclamation and Mine Drainage Conference and Third International Conference on the
Abatement of Acidic Drainage, U.S. Geological Survey Open-File Report; 94-264,112 pp.
Sobek, A.A., Schuller, W.A., Freeman, J.R., and Smith, R.M|> 1978.,^§||p Laboratory
Methods Applicable to Overburden and Minesoils/e*^^^ •-«»?«-- -M*^
Agency Report EPA-600/2-78-054,204 pp.
U.S. En
Sullivan, P.J. and Sobek, A.A., 1982. Laboratory We
and the Environment, vol. 14, pp. 561-568.
Taylor, J.K., 1988. Defining the Accuracy, Precision
In: Keith, L.H., ed., Principles of Environment
Salem, MA, pp. 101-108.
Triegel, E.K., 1988. Sampling Variability
Principles of Environmental Sa,
385-394.
U.S. Environmental Protection
Preparing Quality Assw
Assignee, Report^li-005/80,
imits of Sample Data.
Chemical Society,
rn: Keith, L.H., ed.,
ociety, Salem, MA, pp.
im Guidelines and Specifications for
!ce of Monitoring Systems and Quality
|gy (U.S. EPA), 1983. Methods for the Chemical Analysis of
1-79-020, Revised, 1983.
|on EPA), 1986a. Test Methods for Evaluating Solid
of Solid Waste and Emergency Response, Report SW-846,
with revisions to January 1995.
Environmental Projection Agency (U.S. EPA), 1986b. A Procedure for Estimating
Monofilled 'Waste Leachate Composition, U.S. EPA Technical Resource Document,
U986.
Protection Agency (U.S. EPA), 1989. Seminar Publication: Transport and
*0/Contaminants in the Subsurface, Office of Technology Transfer, EPA Report
625/4-89-019.
U.S. Environmental Protection Agency (U.S. EPA), 1994. Acid Mine Drainage Prediction,
Special Waste Branch, Office of Solid Waste, U.S. Environmental Protection Agency,
Washington, D.C., EPA-530-R-94-036.
C-45
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Mining Source Book
Appendix C — Characterization of Ore, Waste Rock, and Tailings
U.S. Environmental Protection Agency (U.S. EPA), 1996a. Method 1631: Mercury in Water by
Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence Spectrometry, Office
of Science and Technology, Report 821/R-96-012.
U.S. Environmental Protection Agency (U.S. EPA), 1996b. Method 1632: Determination of
Inorganic Arsenic in Water by Hydride Generation Flame Atomic Absorption, Office of
Science and Technology, Report 821/R-96-013.
U.S. Environmental Protection Agency (U.S. EPA), 1996c. Method
Hexavalent Chromium by Ion Chromatography, Offiee of Sci
Report 82 l/R-96-003.
of
U.S. Environmental Protection Agency (U.S. EPA), 19||a. Meth&dl637:
Trace Elements in Ambient Water by Chelatior^^^onc^tration with
Atomic Absorption, Office of Science and 821/R-96-
Inductively Coupl
Re|p|;|21/R-9
'•' m.
U.S.
Water ffijjJFjice Metals t
U.S. Environmental Protection Agency (U.S. EPA), lft|
Trace Elements in Ambient Waters by Inductive
Office of Science and Technology, Repo:
U.S. Environmental Protection Agency
Trace Elements in Ambient Wate,
Absorption, Office of Science
U.S. Environmental Protection
Trace Elements in Ambijjjf Waters.
'-Mas,
': Determination of
-Mass Spectrometry,
': Determination of
Graphite Furnace Atomic
/R-96-006.
. Method 1640: Determination of
'lotion Preconcentration and
y, Office of Science and Technology,
gJ.S. EPA), 1996h. Method 1669: Sampling Ambient
'iter Quality Criteria Levels, Office of Science and
11.
U.S. Environmental ProtJcttdi Agency (U.S. EPA), 1998a. EPA Guidance for Quality
Assurance Project Plans, EPA QA/G-5, Office of Research and Development Report
EPA/600/R-98/018, February 1998.
U.S. Environmental Protection Agency (U.S. EPA), 1998b. EPA Requirements for Quality
' Assurance Project Plans, EPA QA/R-5, Review Draft dated October 1998, available from
http://www.epa.gov/rlOearth/offices/oea/epaqar5.pdf, viewed 11/13/98.
C-46
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
1.0
2.0
4.0
D-l.
D-2.
D-3.
TABLE OF CONTENTS
GOALS AND PURPOSE OF THE APPENDIX D-l
1.1 Water Quality Standards and Effluent Limitations D-l
1.2 Considerations Regarding Predictive Modeling of Effluent Quality D-2
MINE DRAINAGE
2.1 Determining Mine Drainage Quantity and Discharge
2.1.1 Analytical Solutions
2.1.2 Numerical Models . .f:
2.1.3 Calculations Based On Hydrologic Control Volumes
2.2 Determining Mine Drainage Effluent Quality A?.X. I
2.2.1 Considerations Regarding Constituent Analyses
2.2.2 Direct Measurement of Mine Drainage Quality
2.2.3 Predictive Modeling of Mine Drainage Quality
D-3
D-3
D-5
D-5
3.0 WASTE ROCK AND SPENT ORE PILES
3.1 Determining Water Quantity and
r*5*.
3.2
3.1.1 Hydrologic Evaluation,
3.1.2 Other Models ...
3.1.3 Considerations foi
Determining Effluent Qjility froj
3.2.1 Measuring
3.2.2 Empirical JBEctionsj
3.2.3 PredictivJllodelins
/aste
at Exist
'.ffluentJ
M Spent Ore Piles
i Facilities
lity from Proposed Facilities
lity from Proposed Facilities .
D-ll
;k and Spent Ore Piles
D-ll
LP) Model.... D-l3
D-l 5
D-15
D-16
D-16
D-16
D-l 8
4.2
IPmg
sunn?
D-19
gantity and Discharge from Tailings Facilities ...... D-20
lity from Tailings Facilities ................. D-21
"Quality at Existing Facilities ............... D-22
X)WROI
.g Quality from Proposed Facilities D-22
FFLUENT QUALITY FROM A MINE SITE D-23
STORM WATHf D-24
.REFERENC
D-26
LIST OF FIGURES
Conceptual model of components that affect pit lake water quality ............. D-10
Conceptual model of water flow through a reclaimed waste-rock facility ........ D-l 4
Processes that affect subaqueous sulfide oxidation in tailings impoundments and the
quality of tailings impoundment water ................................... D'25
D-i
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
1.0 GOALS AND PURPOSE OF THE APPENDIX
Hardrock mining operations can generate large quantities of effluent that are discharged to
surface and ground water. The primary sources of effluent include drainage from mine workings,
seepage and runoff from tailings impoundments or dry tailings piles, seepage and runoff from
waste rock and spent ore dumps, and runoff from disturbed areas. The quantity an4 quality of
effluent generated from each of these areas and facilities is a function of hydrological and
geochemical factors as well as the engineering design for the facility. Itife|esseratial for mine
operators and applicants to predict with a high degree of cerjainty ther,i||^^^all effluents from
mine operations and waste disposal facilities that will or npplie discna^^tl^^irface waters
during all stages of a mine's life—development, operati^p closure, asii^SeifeiftSlsvThis will
enable the operator to predict and assure compliance wijljwater
impacts to surface and ground water resources.
"£§
A detailed discussion of water quality standards and desi
provided in the main text and in Appendix B, ReceivingjilPa
summarized in Section 1.1 below. In addition, the main text p:
regulatory classification of the various water?
based and technology-based standards that NP
of receiving waters is
formation is briefly
?ussionofthe
fe water quality-
;rmits.
The principal goals of this appendix are
commonly used to characterize the quajPty and
identify the information related qi
and the Clean Water Act. If te;
water quality- and technology-b Jpl efflue
through plan that jAoJiiate marl
be th
lyrical procedures
if generated at mine sites, and to
thatmujf be provided to EPA under NEPA
"effluentjplter quality does not meet applicable
tetiajjpandards, an applicant must demonstrate
actices and/or water treatment systems will
;e. Accurate characterization of effluent
water qul
meteorolo
transport of e:
facilities, i
Thematadsinthis
manajgpient that are pn
Aprflix C, Character^
s prior
characterize other resources such as site hydrology and
.ogy, waste and materials geochemistry. The fate and
; of the mine (either surface or subsurface) and its
3, dry tailings embankments, and waste rock dumps.
tplement discussions of resource characterization and waste
igement, and Apj
idices for more
^Appendix A, Hydrology, Appendix B, Receiving Waters,
fof Ore Waste Rock and Tailings, Appendix E, Wastewater
: F, Solid Waste Management. The reader is referred to these
liled discussions of these topics.
ity Standards and Effluent Limitations
ar quality standards for receiving waters are discussed in Appendix B, Receiving
Waters. Under the Clean Water Act, each State'must classify all of the waters within its
boundaries by their intended use. Once designated uses have been determined, the State must
establish numeric and narrative water quality criteria to ensure the attainment and/or maintenance
of the use. State water quality standards and implementing provisions are approved by EPA and
are codified in State regulations.
D-l
-------
EPA Region X Mining Source Book
Appendix D — Effluent Quality
The CWA provides that the discharge of any pollutant to Waters of the United States is
unlawful except in accordance with a National Pollutant Discharge Elimination System
(NPDES) permit. Section 402 of the Clean Water Act establishes the NPDES program which
is designed to limit the discharge of pollutants into Waters of the U.S. from point sources
through a combination of various requirements, including technology-based and water quality-
based effluent limitations (40 CFR 122.1 (b)(l)). An NPDES permit must contain any
requirements in addition to, or more stringent than, promulgated effluent limitation guidelines
or standards necessary to achieve water quality standards, including Sta|e narrafjll criteria for
water quality. NPDES permits are required to limit any pollutant or pi|utaat?parameter that is
or that may be discharged at a level that causes, has the reasonable p^iS^S|to cause, or
contributes to an excursion above any water quality critejppf' See .for a more
detailed discussion of the development of NPDES pernjp6onditions^ici^lapiteuent ^
r r Ss-r ^-. , '•'•:.5ll3;2,ii. .-"
limitations.
It is important that applicants be able to predict
applicable water quality standards. A common probl
discharge permit applications is that metals are analy:
are higher than the water quality criteria. It is impo:
to ensure that:
Appropriate methods and dete
All necessary constituents ar
Data are obtained for total and disso
The number of samples'collected ijgjfiequate
variability in effluent qiplity (Sa
detail in Appendix B*Receivin
incentrations in lignt of the
many mining-related
detection limits that
.d analysis program
metals, and
:curately characterize expected
lalysis Plans are described in more
.odeling of Effluent Quality
1.2
luent qoapl^Qfien are based on modeling that uses water quality and
hydrological daj&;^S||p||ate the g§oc|iemical species present at equilibrium, the geochemical
reactions thatijare^Kfe^i^^cur under the physical conditions that prevail, and physical
transport They requife^tewafd modeling approach in which assumptions regarding the initial
state of a system and its'ipjiidary conditions are used to simulate the consequences of particular
geochemical reactions (4|pers and Nordstrom, in press).
Alpers and Nordstrom (in press) discuss limitations to geochemical modeling and cite
several cautionary measures that should be followed by those who create and interpret models of
effluent quality. These measures apply to each of the modeling discussions below and are not
repeated therein. Important considerations cited by Alpers and Nordstrom include:
• Modeling is an inexact science subject to numerous uncertainties and limitations.
• Models are not reality and may not be a reliable, correct, or valid representation of
reality; they are only a tool to increase understanding.
D-2
-------
EPA Region X Mining Source Book
Appendix D — Effluent Qualify
Geochemical models can never be proven as true in an absolute sense, their results are
useful only insofar as they can be used to improve or disprove the original conceptual
model.
Analytical and thermodynamic data must be scrutinized for accuracy and internal
consistency prior to their use.
Chemical data used as input should be highly accurate and precise because errors can
be exaggerated when propagated through model calculations. ^
Standard errors should be clearly identified during sensitivity analyses; *""'
Model assumptions should be clearly identified, especially with regard to parameters
such as redox potential. ^
Speciation calculations indicate those reactionj^tf'are thermodynamically favored,-
not necessarily those that are likely to occur. ' " '"""^
Interpretations of ground water chemistry refjpfre knowledge of the flow spstepC
aquifer mineralogy, and effects of sampling.^p^ , '•';*
Forward modeling places more responsibilit^p^^|er to make appropriate choices
with regard to phase, components, and reactiol
Types of modeling applicable to different types*of efflu
the following sections. Regardless of the specific
following should be submitted to EPA to
• Description of the model
• Identification of all
the parameters were d
and whether they
• Discussion
sitivity
.eters.
MINE DRAIN JEE
sed in more detail in
lation such as the
gulatory purposes:
IF
late for the particular use
including discussion of how
:ment, calculation, or assumption),
of modeling
are commonly
of this ap;
the only jJtTels that
on 6.0) provides additional information related to the use
appendix discusses a number of specific models that
. Applicants should recognize that it is not the intent
ive list of available models nor to suggest that these are
Jfncludes waters that drain from or infiltrate into historical workings and
d active surface or subsurface mining operations. Although drainage can be
-../from active or historical workings, applicants for proposed mines will need to
quantities and compositions of these waters. The NEPA review and CWA
permitting processes will require applicants to provide accurate assessments of mine drainage
volumes and quality during operations and after closure. (The main text describes the regulatory
definition of "mine drainage")-
2.1 Determining Mine Drainage Quantity and Discharge
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
Mine drainage from historical workings can be measured using techniques similar to
those for measuring surface discharge. Typically this requires installing a stream gauge or other
measuring device at the point of discharge. Some subsurface mines, particularly shallow adits
and underground workings, may exhibit seasonal flow that occurs in response to snowmelt or
other climatic factors. Where this occurs, applicants will need to characterize the magnitude of
seasonal flow from all historic workings. For mines that are flooded and will be dewatered,
maps of historic workings (if available) or records of mine production can provide sgme measure
of the volume of drainage water that will require disposal. 4.
Dewatering (e.g., pumping ground water from) mine^srorkings. adtts/lr open pits is
required when the mine elevation extends below the poten||p&etric surfafee in confined aquifers -
gro
undergro^H iftaa^is excavated, the
water system? A mine can
water from km^e?,
or in-pit wells ^perimeter
creating a "cone of
pumping operations
and storage, and the
bs may be used for
•discharged to surface
Jty'
or below the water table in an unconfined aquifer.
workings serve as a ground water sink that affects the
capture ground water recharge and stream flow and
Underground and pit mines are typically dewatered us
wells, and/or sumps. Pumping ground water lowers the
depression" in proximity to the mine. The quantity ofjsfiter
depends on the pumping rate, aquifer hydraulic conductivity,
homogeneity of the aquifer. Water produced
process operations, disposed via evaporation
waters.
Applicants proposing operatipjnsin whicbjfpit lakeffe ebpected to form after dewatering
operations cease will be expected tflfsffmate Iwrate at wMfch the lake will form and its final
elevation. A lake water balance EHpt^onsiderlactors as the rate of ground water inflow,
contributions from surface runoff and precipjt^tion^a^posses from evaporation, seepage, or
discharge. The water balance .should lead IresjtiSaiis of the equilibrium lake level and the
' •'•%'' *" a «lii$$®%&V
amount pftiineit will take untitthis level is^pSeved. Applicants should also determine whether
1 '^§JW'; ?N^' ^f* ?*&& *.
there wiltbe^a^^^iiarge frons^%^^ake, and the quantity and seasonality of any discharge.
logy and ground water discharge at mine sites are
discussed in Appei^c^ifi^ro/o^^tJydrogeologic characterization studies should include
geological .descriptions of fee si|e, including descriptions of rock types, intensity and depth of
weathering, and the abundanceiand orientation of faults, fractures, and joints. Although difficult
to evaluate, the hydrologic effects of fractures, joints, and faults are especially important to
distinguish and characterize. Water moves more easily through faults, fractures, and dissolution
zones, collectively termed secondary permeability, than through rock matrices. Secondary
perflfceability can present significant problems for a mining facility because it can result in a
greater amount of ground water discharge to a mine than originally predicted.
Three methods are used to estimate ground water inflow to a mine; all are generally
applicable to both open pit and underground mines:
• Analytical solutions for flow to a simplistic analog, such as a well or trench;
• Numerical ground water flow models based on a representative conceptual
hydrogeologic model and a mine plan, and;
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
• Hydrologic control volumes to calculate inflows.
Applications of these general methods are briefly described below. Regardless of the
methodology used, the quantity of ground water discharged to a mine and the resulting volume of
mine water produced must be accurately characterized. This often requires applicants to
determine whether mine development activities (e.g., blasting) would affect seasonal inflow or
change recharge/discharge relationships, either of which could impact the amount o£drainage.
The discharge of water to a mine can potentially affect the effluent quality of bothsofthe mine
water and of ground water flowing downgradient within an aquifer. Acjirate determinations of
the rate of inflow is specifically required to design water tregjnent sysfcii^^ls important,
therefore, to couple studies conducted to determine the
mine with those to characterize water quality.
to or from a
2.1.1 Analytical Solutions
A common method to analyze ground water in
analytical solution in which the mine pit is approximai
constant-head Jacob-Lowman (1952) equation to calc
as a numerical (modeling) solution, this method
inflow to a proposed mine. It generally yield;
required to dewater a mine (Hanna et al.
of interfering wells, where each drift f<
cumulative production of the simulat
and the extent of drawdown.
2.1.2 Numerical Models
groi
ine relies on a simple
method uses the
ipugh not as accurate
of the rate of water
pumping rates
ethod uses the technique
lisidered to be a well. The
ie total influx into the mine
a variety
Available
methods for so!
difference a
schemesj^widely u
>roces
[els to simulate heterogeneous systems in which
the hydrology of near surface and deep aquifer systems.
jut incorporate either finite-difference or finite-element
Sis for ground water flow. A comparison of finite-
methods is detailed by Finder and Gray (1977). Both
sop.
vernuf
lumei
[late transient flow in aquifers (Freeze and Cherry, 1979).
.erical ground water models are given in Appendix A,
ions of commor
fogy and Section Jf^ODFLQW (McDonald and Harbaugh, 1988) is perhaps the most
applied ground flow model and its use is accepted by most regulatory agencies. In
Ion to simulatinpjsurface flow, this model has been used to simulate inflow to a mine pit
" a pit lake after dewatering operations cease (Bursey et al., 1997).
!ig to use other software packages should check with regulatory agencies prior
• modeling efforts.
The predictive capabilities of numerical models depend on the quality of input data. The
accuracy and efficiency of the simulation depend on the applicability of the assumptions and
simplifications used in the model, the accurate use of process information, the accuracy and
completeness of site characterization data, and the subjective decisions made by the modeler.
Where precise aquifer characteristics have been reasonably well established, ground water
D-5
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
models may provide the most viable, if not the only, method to adequately predict inflow to a
mine, evaluate dewatering operations, and assess mining operational variables.
Estimates of the fate and transport of potentially contaminated ground water discharging
from an abandoned surface or underground mine downgradient or to surface water bodies
generally require numerical modeling. Estimates of the transport of dissolved constituents
through porous media is highly dependent on accurate input data to characterize transport
mechanisms such as convection, hydrodynamic dispersion, chemical sorption, andilrst-order
decay.
2.1.3 Calculations Based On Hydrologic Control Volumes
*^ ^•*r / ^_! *'.^'
This method estimates the volume of ground wi
occur in a given control volume. For mine drainage d
defined as the volume of water-bearing rock that wouldl
method applies water balance calculations to determine
the exposed mine area (e.g., exposed aquifer) (Singh
calculation is first applied to estimate the volume of grlfund wai
expected to enter a mine based on average or esti
evapotranspiration and the surface area of the
applied to estimate the volume of ground wafer that
depletion of ground water storage. Thisjfemate i
specific yield or drainable porosity, the-€urface of the
the elevational head between the pre^4nlning wjfilr table
These two calculations are then combined
to enter the mine from recharge Jfid subs
«&•
<3*>%
TheoQHtepl voh
»*
insufficient to-jpjjform nur
stream flow. In
'
Jed by a mine. In"prieral, the
id rate of water inflow to
A water balance
that would be
n, runoff,
water balance is then
to enter a mine from
;d or estimated factors for
aquifer, and the difference in
the lowest portion of the mine.
tal volume of ground water expected
should^oj^b^applied when ground water data are
lalytical analyses. The method is subject to errors
.d long-term measurements of precipitation runoff and
drogeological conditions, the method potentially
stages of mine development. After ground water
has been drained from^Skrfage/most ground water discharge to a mine occurs from recharge by
precipitation and stream Infiifetion.
2.2 Determining Mine Drainage Effluent Quality
Applicants, will need to estimate the quality of mine drainage effluent produced by their
operations. For sites with historical workings, mine drainage can be sampled and analyzed.
Mine drainage may also be available for analysis from exploration activities. For new mine sites,
mine drainage quality will need to be estimated using geochemical models and testing. In cases
where pit lakes are expected to develop after mining ceases, applicants will be required to
estimate the long-term quality of these waters.
2.2.1 Considerations Regarding Constituent Analyses
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
For NPDES permitting purposes, the constituents that should be analyzed/predicted in
effluents that are to be discharged to surface waters are the parameters identified in applicable
effluent limitation guidelines and any pollutant that the applicant knows or has reason to believe
may be present in the effluent. The latter is in turn governed by mineralogy, mining activities
(e.g., blasting agents that may be added) and site characteristics. The level of analysis (e.g.,
detection limits) depends on applicable water quality standards. Constituents not necessarily
important for NPDES purposes (such as conductivity and major constituents) may be important
for geochemical modeling, selecting wastewater treatment processes, etc.
•^*tAi~>'^5jp» -:*+•" , t • •
w$ii®£metal species m
?*'S:"fe'Ss\j;-K*>
or time. ,s
Initially, it is usually important to evaluate a relativeJ|Marge n
order to determine whether any exhibit concentration chanppiiat
Analyses should be conducted for major constituents sudlas iron,
well as for trace metals such as antimony, arsenic, boro|| cadmiu|%-chromium, copper, lead,
manganese, mercury, nickel, selenium, silver, and ziip^Anal^Ks of other trace metals may
be appropriate when dictated by the mineralogy of encountered and on the
water quality standards designated for the receiving analyses should be
conducted to determine both dissolved and total me
Receiving Waters). Where static, kinetic, and leach
quality (see Appendix C, Characterization ofOr^
should include evaluations of stable and exp
Appendix B,
to indicate water
), data analysis
iselation t^Heasured pH and Eh.
In determining mine drainage qi
be introduced through chemicals used ij|inine dejpiopim
chemicals may be present in mine^firmge use of i
operations that use-ANFO can levels
mine effluent. Similarly, smfiicms need
r
sider constituents that may
Operation, Specifically, residual
Slosives. For example, blasting
lonia (NH4) and nitrate (NO3) in
rtential effects on mine drainage from
any mate:
it will be.
Its
. to the!
^failings)
^K
will need to
required
cause, or cj
narratiyj
and ^p permitting aut
be Kformed.
lyses, tests to determine whole effluent toxicity (WET)
pharges. As with chemical parameters, WET limits are
the discharge has the "reasonable potential" to
istream^fcursion of a numeric WET water quality standard or a
gcs in toxic amounts"). Applicants should coordinate with EPA
determining the number and type of WET tests that should
tent of Mine Drainage Quality
_,.Jurement of mine drainage quality is possible at sites where historic workings
^MMSM^S?*" these instances, applicants can use sampling and analysis procedures similar to
determine baseline surface and ground water quality (see Appendix B, Receiving
Waters). Although direct measurements provide valuable data, applicants should exercise
caution when extrapolating these values to a proposed project. For example, an operation
proposed at a site with historic workings may extract ore that is mineralogically different from
that which was mined previously. In cases where historic operations were conducted in oxide ore
and proposed operations will operate in sulfide ore, historic water quality is likely to be a poor
D-7
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
indicator of future water quality. Moreover, historic workings may contain multiple water
sources with different water quality characteristics (e.g., Reisinger and Gusek, 1998), each of
which may require evaluation in light of host rock and aquifer properties. Similarly, drainage
from exploration activities may not be representative of full-scale mine development.
Studies and sampling designed to characterize the quality of ground water removed by
dewatering operations should:
Characterize the existing ground water quality in the vicini^»|he^oposed mine
Determine the impacts to water quality from ming|developj^^i^§|., effects of
^•>o".^v.i&!" V~-" ^ "J
blasting and the potential for acid generation
Define temporal differences in water quality
long-term. In general, natural ground wat
a seasonal basis, but it may exhibit seasonal!
exposed, near salt water intrusion areas, andl
Brown, 1997).
Characterize the ground water flow regime^
Characterize each lithologic unit the mine
times the depth of the proposed mine
Define water quality hi both prims
fcpose
: could
lity
id generating"
u'ttent and influ
inte
jsions.
uts at depths up to 1.5
1997]
depths and lithologic units withjprnighejj
principal conduits for water ajfniissolvj
porosij|pystems, but focus on
these materials are the
wn, 1997).
There is no specific guidanp&fcff det
collected to characterize mine
lithological and hydrologicaL the
accurately define the avera^^^ian, an>
the influenl&illariy, of
'..•:' .i^Ji'Li^i''^. Jkv.'',*fe
The
effects from t
should be ca
ing the njfniber of samples that should be
Becausjjlach mine site occurs in unique
oJl»fiples collected should be adequate to
instituent concentrations, and to quantify
it quality.
.epends on specific site conditions, lithology, and
;e/discharge relationships. At a minimum, sampling
st one year to define potential temporal effects and
hout mine development and operation.
sampling should contr
.-. vlH-y
2.23 Predictive Modeling of Mine Drainage Quality
Predicting the,quality of mine drainage is not a simple task (see Section 1.2). The
following discussion considers three possible scenarios:
"- •••
• * Mine drainage that does not contact mine workings,
• Mine drainage that contacts mine workings, and
• Mine pit lakes.
Mine drainage includes ground waters that are pumped from aquifers by dewatering
operations. In areas where this water is removed from ground water storage without contacting
mine workings or materials, mine drainage quality can be estimated using the measured baseline
ground water quality, as discussed in section 2.2.1. Some mines may pump water from two or
D-8
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
more aquifers and manage these waters together. In these cases, aqueous equilibrium
geochemical models can be used to determine whether mixing will cause chemical effects such
as mineral precipitation or desorption.
Dewatering operations may permit ground waters to contact mine workings prior to
removal. In such cases, estimates of mine drainage quality will need to account for possible
constituent contributions from the mine workings. The results of leach tests, kinetic tests, or
minewall washing procedures can be used alone or in combination with computef iodels such as
MINEWALL to estimate contributions from exposed, reactive rock surfajes (yfi^fD 1995-
Morin and Hurt, 1995). ** "
Open pit mines may flood and form pit lakes
Applicants will be expected to estimate the quality of I
understanding of how it may evolve with time. The p
D-l, which shows a conceptual model of the important
quality, including:
Lake water balance,
Ground water composition,
Geochemical reactions, and
Wall rock contributions.
swateringj
[ water an||«ierno:
is complex, as illus^|j|||pgure
its affecting pit-lale^water
Of particular importance are
must predict the timing, quantity,
The lake water balance,
required tositeluate lake
addition
volumes
(Bursey et
quality charac
differ from
from
discharges, and applicants
charges.
is a critical piece of information
T, 1998) and the potential for discharge. In
lake volume, the water balance indicates the
[oads that would be contributed from different sources
it water sources are likely to have different water
ff from exposed pit walls will have characteristics that
•aste rock pile. These compositions can be estimated
iples of materials that will be exposed in the pit walls. Ground
ther source. Waters contributed from each source can be
ich they are expected to occur using an equilibrium geochemical
This weighted mix can be used as an estimate of water quality
Isigning source compositions will require applicants to use best
. the application of kinetic test results, leach test results, and surface and
analyses.
ilibrium geochemical models can be used to evaluate how baseline water quality
might evolve in light of the final physical character of the lake (e.g., outflow or terminal; volume;
surface area, etc.). These calculations would determine how water quality would change in
response to reactions between lake water and wall rock, through precipitation of mineral phases,
as a result of adsorption reactions, and in response to biological activity (see Kempton et al.
(1998) and Bursey et al. (1998) for a detailed discussion of the wide number of variables that
applicants may need to consider). Final pit lake water quality will also require consideration of
D-9
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
the physical limnology of the pit lake (Atkins et al., 1997; Doyle and Runnells, 1997) and the
effects of long-term processes such as evapoconcentration (Bursey et al., 1997). Physical
limnological considerations include chemical or physical stratification of the water column,
seasonal overturn, and circulation.
D-10
-------
Pit-Lake Conceptual Model
Precipitation
yy Wall Rock
|C Oxidation _
r&,-\ f _ Y -
Ground Water
Outflow
Figure D-l. Conceptual model of components that affect pit lake water quality
(modified from Kempton et al., 1998)
D-ll
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
3.0 WASTE ROCK AND SPENT ORE PILES
Seepage and runoff from waste rock dumps and spent ore (e.g., heap leach) piles' are
sources of effluent. It is important that effluent from these units be predicted during both
operations and closure. The materials in these units are composed of comparatively coarse-
grained materials that are unsaturated to partly saturated. The potential for seepagejis high in wet
environments, but less certain in areas where annual precipitation is less than about 380 mm/yr
(Swanson et al., 1998).
are
To accurately predict leachate and runoff water qitajpEy and quaiifreoaires an
understanding of both the hydrology and geochemistry ojple pile.
determined by the physical configuration of the pile, itsl^gineering^esign and
construction, the distribution of geologic materials witb^|^esp^ially the
acid neutralizing materials), the addition chemicals to and the
transport of water through it (SRK, 1992). According it is extremely difficult to
predict the quality of water that will emanate from a pile because there is
no single analytical method or model that accurately temperature, air
and water transport, oxidation, neutralization models are
presently being developed (e.g., Lin et al., 1997;^pian et al., 1997). It is
important for mining hydrologists and geo
with hydrological studies to provide conservative
if
3.1 Determining Water Quantity and D
a,
Precipitation that falls onto the surf.
infiltrates or flows laterally as runoff.
.sSiBai. .A^item
s for geochemical testing
quality.
Waste Rock and Spent Ore Piles
rock dump or spent ore pile either
Swansin eteal. (1998||il^toe a conceptual model of the hydrology of a pile of coarse
•-. •..-",'. i. : x/'.j}w\\ ^ •>'iv;.^;!OVj^.4^'V'.N r * ^J *
waste materia|s|i^^an be use^^^^|is for hydrological modeling. It contains three major
components (seeil5^|&p-2):
active surface zone,
Percolation thiliiiMie waste materials, and
. i'-^jiv *%>••;
• Seepage at the'basefof the facility.
Under unsaturated conditions, water percolating through a disposal unit will gradually
wet the materials and, depending on local conditions and material properties, will be stored in
1 Spent ore is ore from which it is no longer economic to leach or otherwise remove valuable
minerals. Spent ore can be in the heaps or dumps where leaching occurred or in repositories where leached
ore is moved following detoxification. (Note that applicants should predict effluent quality during active
operations for any discharges that may occur, including discharges under the NPDES "storm exemption."
The latter is important when the predicted mine life amounts to a substantial proportion of the return interval
of the facility's storm-surge capacity—a predicted 15-year mine with capacity to store all precipitation from
a 25-year storm, for example.)
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
pores within the pile. For homogeneous piles of coarse rock, water is likely to be transmitted
quickly to the base of the pile (Smith et al., 1995). Many waste rock dumps, however, are not
homogeneous piles of coarse material, but instead are composed of a mix of coarse and fine
materials that have undergone some degree of segregation through end-dumping or other
construction practices. Particle segregation can creates unit-specific hydrological characteristics
that can lead to preferential flow through fine-grained waste rock layers as described by Newman
et al. (1997) and Swanson et al. (1998). Seepage from the base of the pile may occur when
storage is depleted or the hydraulic head is sufficient to force water through the toe of the dump.
Depending on the nature of the foundation materials and the topographic'settingif the dump,
seepage may flow laterally from the base of the dump or percolate downward* into the substrate.
Flow through a heap could be somewhat different, since the materials, and the subsurface are ;
likely to be somewhat different themselves. Although nominally homogenous^sre may haveji-1
been agglomerated with cement or other materials, and |here may be zones of lowpermeability
throughout a heap or dump. Flow through heaps and
site planning, and these data may be useful in predicti
ore piles and dumps.
Aspects of engineering design influence the production i
dumps and spent ore piles (see Kent, 1997 and.
include the:
have been
other flows through spent
waste rock
\agemenf). These
-.,
thlf waste materials;
., steeplrfibuntainous terrain versus valley fill
article sjffe* segregation that would occur from the
Range of geotechnical and h;
Topographical location of
sites);
Mode of disposal andJgpTxpecti
dumping method;
; constructiojAcBiickness
;rate
*r&7K&¥S£££Q&£C&*33?^i3?#@3£fi3&&3&.
i, such as placement of low-permeability clays or other
|gjye soils or placed materials;
[eluding internal drainage layers and foundation drams;
potentially acid or other contaminant generating
ration or other means of treatment; and
igical properties of the foundation.
evaluating ifpuent production, applicants should consider factors in addition to
lertain operational practices, such as concurrent reclamation, use of daily or
ksonal operations, all would affect the quantity of effluent from dumps and
factions taken at closure, such as topsoil replacement, compaction of cover
matemis;^ev'egetation would affect effluent quantity. Applicants should consider and account
for all variables that could affect the production of effluent through all mine life stages.
Most methods to characterize the hydrology and estimate the volumes and rates of runoff
from and seepage through waste rock or spent ore piles use a water balance approach. In typical
water balances, analytical methods to determine runoff and infiltration are combined with
analytical or numerical solutions to estimate unsaturated and saturated flow through the
D-13
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
embankment. The Hydrologic Evaluation of Landfill Performance.(HELP) model (Schroeder et
ah, 1994) combines several analytical hydrological procedures and provides volume estimates of
surface runoff, subsurface drainage, and leachate that are likely to result from different waste pile
designs. Because of its widespread application, the HELP model is described in detail below.
Other models that have been used to characterize waste pile hydrology include MODFLOW,
SUTRA, SEEP/W, and FEMWATER/FEMWASTE; these models are briefly described in
Section 3.1.2 (FEMWATER/FEMWASTE is described in Appendix A, Hydrology^
3.1.1 Hydrologic Evaluation of Landfill Performance (HELP) Model
The HELP computer program (Schroeder et ah, 1
that can be used to compare effluent generation and run'
model uses meteorological, material, and design data t<
estimate parameters such as surface storage, snowmelt,
vegetative growth, evapotranspiration, soil moisture sto!
recirculation, unsaturated vertical drainage, and leakagi
composite liners. HELP can be used to evaluate vario
unreclaimed'surfaces and surface soil caps, waste cells!!
barrier layers, and synthetic geomembrane liners
annual, and long-term average water budgets.
; a qua:
HErom vari
lensibnal models
runoff, infi
al subsurface
geomembranes or
f reclaimed or
low permeability
aily, monthly,
, leachate
HELP simulates precipitation anjjpther mejp>ro
generation model (WGEN) developedjjrRichardjpon and
be input by the user, generated sto^p&ally, gpliken fro
the model. Daily temperature radiglln data;
stochastically. Determinations
Agriculture, So jl Conserv;
Hr radii
loff
/ice (S
Pot
••
'tions using the weather
"(1984). Daily rainfall data may
ran historical data base contained in
can be input by the user or generated
ing the United States Department of
.ber method (SCS, 1985), which is
Penman:
interception^
Vertical drainal
Campbell Q$i
solution of the Bouss:
Each of these processes
for runoff and a surface
usir
"apotranspiration is calculated using the
HELP model also incorporates routines for estimating
.derson, 1973), and frozen soil (Knisel et ah, 1985).
:ed and unsaturated relationships described by
fetermined using approximations of the steady-state
ion and the Dupuit-Forchheimer assumptions for lateral flow.
Sequentially by the HELP model, starting with determinations
balance. It then applies evapotranspiration from the soil profile
and finally determines djainage and water routing, starting with infiltration at the surface and
then calculating seepage through the pile.
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
1} Infiltration from beneath
the active surface zone
21 Percolation within the
vraste-rocfcfacility
Figure D-2. Conceptual model of water flow through a reclaimed waste-rock facility (from
Swanson et al., 1998).
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
3.1.2 Other Models
MODFLOW (McDonald and Harbaugh, 1988) is a block-centered finite difference
program that can be used to simulate steady-state and transient flow in two or three dimensions.
Simulations can be run for porous media in confined and unconfined aquifers above an
impermeable base.
SEEP/W (Geo-Slope International, 1995) is a two-dimensional finite elemiit program for
ground water seepage analysis. The program permits analysis of sati
seepage as a function of time, precipitation infiltration, migration of i^
or transient flow, confined or unconfined flow, and excessg>i§e'pressv
software was used by Newman et al. (1997) to model floAfcough c<
simulate a structured waste rock pile composed of layerJiif coarsex.
SUTRA (Voss, 1984) uses a two-dimensional,
difference method to approximate the governing equatio:
transport of either energy or dissolved substances in thj
pressures and either solute concentrations or tempera'
simulation may be used for cross-sectional mod
modeling of saturated flow.
[saturated flow,
•ont, steady-state
>n. The
;dto
which can aceo&ffti^the
mine has been
ie element and inffflfed finite
fluid movement and the
program calculates fluid
time. Flow
ted flow and area!
3.1.3 Considerations for Model Sele
It will be difficult to accuri
spent heap leach pile prior to its
pile (development of layerhij
with any degree of c
'• hydrolcpfcal behavior of a waste rock dump or
lis is bejliuse the physical characteristics of the
;al changes, etc.) cannot be known
i may need to model a variety of scenarios
Icussed by Hutchinson and Ellison (1991),
: estimated using unsaturated ground water flow models
jenl of water caused by capillarity. However, once a
monitoring of meteorological variables and of the
hydraulic condiScti$5i§^OT|ferent gepechnical layers within a waste pile can be used to refine
pre-constraction modelsl^Sffllftent quantity.
^&E£ ^' *<' £&~''?:-*^r^*'V^:'J!s'-
•iff Most numerical 'water models require separate analyses or modeling to create
input for precipitation, iifiltration, evapotranspiration, and runoff. One advantage of the HELP
model is that it combines analyses of surface and ground water components. HELP also allows
meteorological data to be determined stochastically. However, a disadvantage of the HELP
model is that it employs a less accurate method (SCS curve number) to estimate infiltration and
runoff. Runoff can be determined more accurately using the Kinematic Wave Method (Linsley et
al., 1975; COE, 1987; see Appendix A, Hydrology). Infiltration can be more accurately
determined using mathematical methods such as Green and Ampt (1911) or the Richards
equation (Philip, 1969), empirical models such as Horton (1940) and Holtan (1961), or by using
variations of these methods (U.S. EPA, 1998a, 1998b; see Appendix A, Hydrology). However,
the application of these alternative methods requires detailed knowledge of several physical
variables that may be unknown or difficult to estimate prior to construction of the waste rock or
spent ore pile. U.S. EPA (1998a; 1998b) evaluates the variety of available infiltration methods
D-16
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
and provides recommendations on their application; readers should refer to this document for
more information.
3.2 Determining Effluent Quality from Waste Rock and Spent Ore Piles
The composition of effluent associated with an existing waste rock or spent ore pile can
be determined by sampling seeps or pore waters. In contrast, predicting the quality of effluent
that would be generated from a proposed waste rock dump or spent ore heap prior to¥its
construction is difficult and presently cannot be accomplished with a hijldegree of certainty.
This is because the processes that govern effluent quality opeMe at ratelsliiiare difficult to
predict under field conditions. This is especially true for Ajjl
bacterial growth kinetics, and their interactions (Lin et aj|lf!J97).
more difficult when the disposed materials vary in graittj|jze and/oEtameralo^Ip^oiajterials
have been subjected to leaching by process chemicals,
preferential fluid pathways, and when chemical additive
bactericides) are used as amendments during construction!
approaches are used to predict leachate quality from prc
use the results of geochemical testing to provide a measure <
materials (Pettit et al., 1997). Modeling approaclj|^^feuilibriuS.
transfer models, or coupled mass leacl||f: quality (Lin et al.,
1997; Perkins et al., 1997).
even
:.fcS:A -*1
lestone, chelating'&gents,
Consequently, two
Empirical approaches
avior of waste
emical models, mass
In general, the constituents of cjjjfcern woJRl be sirflBiKrthose for mine drainage (see
section 2.2.1). Of particular conce^jn%old hfpTleach fajpities would be cyanide or other
chemicals used as lixiviants, thei^fetdow^poducts^phe case of cyanide, these would
include ammonia and nitrate}, cyanide or other lixiviants.
Applicants jfeuld analyses (weak acid dissociable or
WAD for on applicable water quality standards.
3.2.1 Me
The
romsi
uent
ic process is si
: B, Receiving
Illation of seasoi
jsitions vary wh
Existing Facilities
~f
: prodllpa. from an existing waste rock or spent ore pile should be
jd/or pore waters (for seepage) and run-off (for run-off). In
lat for sampling surface and ground waters described in
j. t^ w
Applicants should be certain to collect enough samples to permit
lhanges in discharge quality and to determine whether pore water
lepth or position in a dump.
Empirical Predictions of Effluent Quality from Proposed Facilities
/jffi?/ ?•} jSPvjP ffl^
'Appendix C, Characterization of Ore, Waste Rock and Tailings, describes the variety of
geochemical and mineralogical tests that can be conducted on waste rock, ore, and heap leach
residues. In general, the results of these tests provide only an indication of the chemical
characteristics that an effluent may be expected to have and they cannot be used to provide an
absolute measure of water quality. In part, this is because leach tests use (comparatively) short
experimental times, simulated leach solutions, and materials with altered particle-size
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
characteristics (most tests require crushing) that affect chemical and physical controls such as
oxidation rates, mineral availability, and fluid flow.
Several factors influence the quality of runoff that is generated during a given storm
event. They include the composition of the solid materials exposed on the surface of the waste
dump, the contact time between runoff and waste rock materials (i.e, runoff flow path), the
duration of the precipitation event, the length of time since the previous runoff event (i.e.,
oxidation time), and the climatic conditions. In general, these factors determine ^composition
and quantity of constituents present on the surface of the waste rock dud||^hat;pjtentially could
be dissolved and transported by precipitation runoff. For example, a rock dump
situated in a humid environment would undergo oxidativqi^aliieringc^^^^^orm events that.
would result in a build-up of oxidation products on the si^Kce <
Precipitation runoff could dissolve and transport these pjfliucts, lesajiirig to an 3
constituents as the most easily solubilized compounds ^g^obiii^a; continuedfi^^^^^show
significantly lower constituent values.
Predicting runoff quality is a difficult und
been established. In general, the results of leachate test! are u;
Most standard leach tests (e.g., TCLP, SPLP,
estimates of leachate composition due to the
(typically 18 to 24 hours), the exaggerated
crushed to sizes substantially smaller
lixiviants used in some tests (pH valuepjior som
Applicants should keep in mind
permit an evaluation of the pot
cells or columns) can be used t<
methodology has not
runoff quality.
conservative
-ock contact time
ples are typically
aggressive character of the
natural precipitation).
d leach tests is that they do not
thering. Kinetic tests (e.g., humidity
portance of oxidation and "flushing".
rr
the methods by which a waste rock or spent
erially true for mines that dispose of materials with
|ing characteristics. Construction techniques dictate
Seepage quality
ore pile is(XM3Straeted.
widely different isiaetiing and
important factors sactas^the of water flow through the pile, the residence time of
water in the pile, aii^tferfi^butidn^f acid generating and acid neutralizing materials within the
pile (e.g., Morin and Moreover, dump design can play a major role in determining
whether^hot spots" of form within a dump (e.g., Garvie et al., 1997) or whether
a dump behaves in a cherniciitfy uniform manner because materials have been evenly distributed
through layering or blending (Mehling et al., 1997). Operations and closure influence effluent
quality as well, as was noted previously, and appropriate operational and closure aspects should
be considered in predicting effluent quality during specific times of a mine's life.
SM— ' -"" . -
In general, statistical analyses of geochemical test results are used to assess the
characteristics of waste rock materials and the quality of effluent that would be generated from
waste rock piles. Pettit et al. (1997) describe applications of multi-variate techniques such as
cluster analysis and discriminant analysis. These analyses can indicate waste rock types that have
similar behavior.
An empirical approach described by Morin and Hurt (1994) predicts seepage quality from
kinetic leach test results. Geochemical production rates (mg of constituent/kg of rock/week) are
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
estimated from test results using "best-fit lines" through test data points. Estimated long-term
production rates are combined with assumed precipitation volumes and total waste rock volume
to yield predicted constituent concentrations. Constituent concentrations determined using this
method depend heavily on the estimate of long-term production rate, which requires careful long-
term kinetic testing. Because this model ignores many of the hydrological and chemical
complexities associated with waste rock piles, it should be used only to approximate seepage
quality.
3.2.3 Predictive Modeling of Effluent Quality from Proposed Facilitit
Perkins et al. (1997) review the applicability of numerous typelof S|uter models to ^
predictions of water quality from waste rock dumps or fe||i leach
describe four general model classes that can be used to tildict watefeejualitvT'^
*,•**• ^j:-. * J \?J
I
• Aqueous Geochemical Equilibrium Models,
• Geochemical Mass Transfer Models,
• Coupled Geochemical Mass Transfer-Flow,
• Applied Engineering Models.
From an environmental perspective, e
Consequently, there is no standardized aj
facilities. The choice of a predictive m
site (see Section 1.2). In all cases, it is^Bportan^pr appli
addressing the task at hand and to statejpi assum
simulations. At most sites, the proJis will
>rt) Models, and
spent ore pile is unique.
lueji: quality from these
model developed for the
'select tools capable of
Ins used to generate model
re an iterative approach in which the
results of early numerical modelire used
that have bemused are
anceptual site model. Several models
dump was'
moving front th
mode
oxidation and oxygen diffusion through a waste rock
>). The Davis-Ritchey model views oxidation as a
te edges of pyrite grains to their cores (the "shrinking
icorporated into numerical models such as PYROX
ig core model has recently been criticized as
(idation rate that occurs as grain size increases (Otwinowski,
Aqueous geocjpmical equilibrium models are static models that use water composition,
ature, and pjlflure to compute equilibria among aqueous species. They are widely used
;k drainage and background stream composition to estimate the precipitation
?f mineral phases and identify the maximum solute concentrations that can occur.
equilibrium models utilize thermodynamic data to compute equilibria; the quality
of these data and the number of species contained in the dataset govern the quality of the
computed results. Shortcomings of this class of models are that they do not consider flow and
they cannot be used to provide a 2- or 3-dimensional picture of chemical equilibrium (e.g., in a
waste rock dump). Examples of this model class include MINTEQA2 and PHREEQC, which are
described in more detail in Appendix B, Receiving Waters.
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
Geochemical mass transfer models are dynamic models that use initial fluid composition,
mineral composition, and mineral mass and surface area to compute a final fluid composition
following fluid-mineral reactions in a closed system. Mass transfer models compute how fluid
composition changes as host minerals dissolve and new minerals precipitate until equilibrium is
achieved. These models have not been widely applied to predictions of effluent quality from
waste rock or spent ore piles. Deficiencies of this class of models are that they cannot
accomodate flow and that important mineral reactions may be overlooked if the computational
reaction step size is too large. Use of an appropriately small reaction step has the negative effect
of greatly increasing computing time. Examples of this model class include Rgpet!, which is
available commercially.
Coupled geochemical mass transfer-flow models
are similar to mass transfer models, but have been exp
Consequently, they are capable of handling fluid com;
by infiltrating precipitation, and concentration by ev:
hold the most promise for producing accurate predictions]
not recommend use of most coupled mass transfer-flo
combine sufficiently rigorous geochemical and flow
presently are developing a new mass transfer-flo
acid rock drainage from waste rock dumps
et al. (1996) have combined the PYROX
MINTOX, which is a 3-dimensional co
oxidation, gas diffusion, and the fo:
.on
ARD
conditi
4.0
that occitt;
.ese models are clSHp'ex but
Perkins et al. (1997) do
they generally do not
jnetal. (1997)
eally for predicting
n addition, Wunderly
iuce the program
that simulates pyrite
mining wastes.
Empirical models do not
limited set of geochemical
models, which can be
managemeat-idions
" • "- ''•-"
.emical relations, but instead use a
ate the observed geochemistry. These
it, are best used for comparing different
dictive applications. An empirical approach
EKMent from
-as described in the Section 3.2.2.
'undments and dry tailings facilities can include process waters
or through seepage and runoff from the facility area.
that are either discharged;
Discharges may be continuous or they may occur only under high precipitation conditions.
TaiMngs impoundments often are used to manage other waters from the site (e.g., mine drainage,
sanitary wastes, wastewater treatment plant sludge). Consequently, flows from other sources
need to be addressed when determining tailings unit effluent quantity and quality.
'j"';C*- .
• It is extremely important that effluent quality be characterized during all stages in a
tailings facility's life. Even if a facility is designed not to discharge during its active life, there
may be a need to discharge during and after closure. The quantity and quality of that effluent
should be predicted. In addition, applicants should take note of the relationship between the
reasonably anticipated life of the mine and the return interval of the design storm. If the life is a
significant proportion of the return interval, then it is likely there will be a storm-related
discharge during the mine's life (see the main text for a discussion of the so-called "storm
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
exemption" to the NPDES effluent limits). Applicants should predict the quality of discharges
under various storm scenarios, including the probable maximum flood.
4.1 Determining Water Quantity and Discharge from Tailings Facilities
Every tailings impoundment will behave in a slightly different hydrological manner that
reflects the impoundment design, construction and management; its physical, hydrqlpgical and
climatological setting; and the physical and chemical characteristics of the materials Contained
within it. In general, tailings solids are retained by an embankment or perimeter dike and are
maintained under a partial to complete water cover. Most facilities an|«nlmed; some have
embankments with impermeable cores or grout curtains tolpilude seepage (Vick, 1990; see
Appendix F, Solid Waste Management). It is assumed thjfithe catchment area contributing '
runoff to the impoundment will be minimized by desigi|||g and cgifstructing appropiiate^tream
and/or runoff diversion structures around the impoum
Estimating effluent from
an accuratejfce water
include
In additK
Seepage
methods lil
dumps, tiri&ctions oi
the amount of effluent that may need to be discharged.
grained materials, the method of tailings disposal can i
permeability and transmissivity. Moreover, facilities
saturated conditions may develop hardpan layers that i
(Blowes et al., 1991).
In dry tailings facilities, tailings
unsaturated conditions (see Appendix F,
concurrent with operation. The materi
form of residual process water or
important for minimizing
rilled with generaHyiine-
size differences that affect
tailings under partially
vertical flow paths
it and maintained under
They are typically reclaimed
es contain moisture only in the
exposed tailings materials.
(wet or dry) begins with the need for
life of the unit. The water balance must
run-on/runoff, evaporation, and seepage.
its sho
tigs fad
estimated discharges during and after closure.
be predicted using empirical, analytical, or numerical
. 1. Similar to predictions of drainage from waste rock
>m tailings facilities require knowledge of the proposed
In addition to the engineering factors cited in Section 3.1,
; design of
tailidpr seepage predicti^^^oire knowledge of the permeability, transmissivity, and storage
ffity of the substratepocal and regional ground water hydrogeology; and embankment
aility.
i as SEEP/W and MODFLOW (Section 3.1.2) can be used to analyze
^Jfpoundments. These models can be used to simulate the migration of a wetting
uwm LLM Uio underlying substrate, the development of a ground water mound beneath the
impoundment, and seepage through an embankment (e.g., Vick, 1990). For dry tailings facilities,
the HELP model (Section 3.1.1) can be used to determine parameters such as infiltration, storage,
and drainage.
Besides estimating the quantity of seepage that may emerge from a tailings facility,
applicants also should estimate quantities of run-off under various storm conditions, and any
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
discharges of process wastewater in net precipitation zones that are allowed under the regulations
(see Section 2.2 in the main text).
A detailed description of methods used to quantify volumes of surface run-off'is
provided in Appendix A, Hydrology. In general, the most appropriate methods for developing
and analyzing runoff from sub-basins or facilites at mine sites, including areas with tailings
impoundments, use a unit hydrograph approach (see Appendix A, Hydrology). A unit
hydrograph is a hydrograph of runoff resulting from a unit of rainfall exqess that is distributed
uniformly over a watershed, sub-basin or mine facility in a specified duration 0f time (Barfield et
al., 1981). The unit hydrograph represents the runoff charac^dstics foi.tibfespecific facility or
^'^j^Sffl&S&fe J f \
sub-basin for which it was developed and is used to quantiipiBe volume ;aiid</
Estimating the volume and timing of discharges
precipitation requires an accurate understanding of the
of methods and approaches used to develop a site wat
Hydrology. In general, an accurate site water balance if require
runoff, stream flows, and point and non-point
and discharge structures. M.L. Brown
balance using both deterministic and proi
of conditions that could be expected to
for average, wet, and dry conditions. Iilpontrasi
approaches are sampled from probajpny distrijtiKions (e.gltannual precipitation probability).
net
Computer spreadsheets are used
According to M.L. Brown
because meyjean indicate
itivel
robabi
4.2 Determining Effluen
Deteeri:
facilities in regit
A detailed description
gided in Appendix A,
fully manage storm
d to design control
ne a site water
.de insight into the range
ances should be computed
used in probabilistic
ow and outflow probabilities.
:es result in better facility designs
iost effect on model results and may reveal
om Tailings Facilities
&'**
of client from tailings management facilities requires an
, beneficiation processes, tailings facility design, mine site water
understanding of ore:
flow, closure plans, and^Sp^gind ground water quality. Consequently, the process used to
estimate tailings effluenf|julpy will vary from site to site. Tailings management plays a pivotal
role-an determining the jptential for water quality impacts. For example, sites may treat process
chemicals (e.g., cyanide) contained in tailings water prior to discharge or they may maintain a
water'Cover over reactive tailings to prevent oxidation of pyritic materials. In general, the metals
leaching potential of tailings depends on the mill process, ore mineralogy, and particle size (Price
etal.,199?).
Constituents of concern should be identified as described in section 2.2.1. In addition,
applicants should monitor for residual process chemicals (cyanide, xanthates, etc.) as well as for
pollutants in other wastes that may be disposed with tailings (for example, fecal coliform and
BOD if sanitary wastes are disposed).
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
4.2.1 Measuring Effluent Quality at Existing Facilities
Tailings effluent quality can be measured at existing facilities by collecting and analyzing
impoundment water quality, pore water samples, and samples collected from seepage ponds and
surface seeps. In essence, the process is similar to that for sampling surface and ground waters
described in Appendix B, Receiving Waters. Applicants should be certain to collect sufficient
samples to permit an evaluation of seasonal changes in discharge quality and to determine
whether pore water compositions vary with depth or position in an impoundment &
4.2.2 Predicting Effluent Quality from Proposed Facilities
From an environmental perspective, every toilingjfimpounclmenf isPratique. ^ |v
Consequently, there is no standardized approach for moving effluent'quality firom tfese £-
facilities. The caveats stated with regard to predictive il^elirig^f'waste rock and spent ore piles
(Section 3.2.3) apply to models of tailings effluent as wefl^Sso^see Section 1.2). ^i8
f
Tailings management is a critical issue, particularly for sites that would produce tailings
containing pyrite or residual cyanide. Studies of active^impoundmeats jsbow that water quality
can vary throughout an impoundment due to diffexqwlftn the rate o£pyrite oxidation (e.g.,
Robertson et al., 1997). For example, thatns regarding the behavior of these environments (steady-
se considerations (Alpers and Nordstrom, in press).
behavior of pyritic or cyanidation tailings should be
. (199|plhowed that water covers may not preclude sulfide
;ead, their work indicated that sulfide oxidation rates, although
ith, wave action, and particle resuspension (Figure D-3).
.e importance of developing a conceptual model that incorporates
as a function
such as this illu;
; of engineering dpign, facility water balance, climate, and materials properties and
>sitions when prjicting effluent quality. The conceptual model serves as the basis for
jing numerjgjKnodels of water quality (see Section 3.2.3 for model descriptions; Botz
scribe a model for natural cyanide degradation that presently is being
Sited).
In general, the models described for waste rock and spent ore piles in Section 3.2.3 also
can be applied to predictions of effluent quality.from tailings facilities. These include
equilibrium models such as MINTEQA2 and PHREEQC and coupled mass transfer-flow models
such as MINTOX. Similarly, the methods described in section 3.2.2 should be suitable for
predicting run-off quality; besides considering constituent additions from native minerals,
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
however, applicants should consider how constituents in process water quality will affect run-off
quality from tailings facilities.
It is assumed that applicants will perform pilot-scale testing for beneficiation operations
to determine/optimize metals recovery. It is important that these tests be conducted with
representative ore feeds with the reagent chemicals expected to be used at the mine. Tailings
solids generated from these tests should be used for geochemical analyses (i.e., static acid-base
accounts, kinetic humidity cell tests, leach tests, and mineralogical tests; see Appendix C,
Characterization of Ore, Waste Rock and Tailings). Water produced during pilot-scale tests
should be analyzed to indicate the general composition of w,a|er to be dfccfaarged to tailings
management units, including residuals from any chemicalslfisM in the proeess/83eochemical A*
.^P^ j J #*L *fjp
analyses and pilot-scale test results can be used to predic^ffffiuent qualify &JBCW ©r as input m^
predictive models.
Price et al. (1997) cite several factors that shoul
effluent quality:
in predictions-of tailings
quali
Other questions ma
-------
EPA Region X Mining Source Book
Appendix D — Effluent Quality
Expected variations in flow and water quality from each source can be combined using
mass balance calculations or modeling. For example, equilibrium geochemical models such as
MINTEQA2 or PHREEQC may be used to compute flow-weighted effluent quality. Such
calculations should determine the average effluent quality and the range of possible effluent
compositions that could occur. If the effluent is to be discharged, the maximum values of
effluent parameters are important. The estimated quality of the combined effluent can then serve
as the basis for determining management practices and/or treatment requirements. ^Treatment
may be required for individual effluent streams only or for the combinedeffluent stream. Where
treatment prior to discharge is a component of wastewater management|iefihiejQtt}uality and
quantity (average and maximum, variability, etc.). followingfeeatmen^H|iife predicted.
Treatability studies may be required to make such predicti^alp^This is ;ifici^e^ in Appendix E.
6.0 STORM WATER
Storm water discharges from active mining areas
combined with mine drainage or process water, may
NPDES storm water permits (e.g., the Multi-sector
Section 2.4 of the Source Book main text) provid
violation of applicable water quality stand
requires monitoring of certain storm water
management practices are working as arrfppated
pp. 42533-42548 for most recent
Storm water sampling guidance
www.epa.gov/owm/swlib.htm.
areas, that are not
:r.individual or general
toer permit for Mining; see
it cause or contribute to a
permit for Mining
ifm water best
,No. 152, August 7,1998,
monitoring requirements).
D-25
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
Schematic Diagram of a Tailings Impoijjlment
Wind
Surface ]:"M
Inflow W*p''f
Figure D-3. Processes that affect subaqueous sulfide oxidation in tailings
impoundments and the quality of tailings impoundment water (modified from Li
et al., 1997).
D-26
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
7.0 REFERENCES
Alpers, CN and Nordstrom, D.K., in press. Geochemical Modeling of Water-Rock Interactions
in Mining Environments. In: Plumlee, G.S. and Logsdon, M.J., eds., The Environmental
Geochemistry of Mineral Deposits, Part A: Processes, Techniques, and Health Issues,
Reviews in Economic Geology, Volume 7 A, Society of Economic Geologists, Littleton,
CO (scheduled for publication in Summer, 1999).
Anderson, E., 1973. National Weather Service River Forecast System -Jifoow ^cumulation and
*!••'/>?',•. --'•?-!"' T.-V
Ablation Model, Hydrologic Research Laboratory, National O(|i|i|pllia Atmospheric
Administration, Silver Spring, MD.
Atkins, D., Kempton, J.H., Martin, T., and Maley, P., lljjjl. Lirnno
Existing Nevada Pit Lakes: Observations and using
Proceedings of the Fourth International Rock Drainagef
British Columbia, May 30-June 6,1997, pp. 697-
Blowes, D.W., Reardon, E.J., Jambor, J.L., and Cherryfj.A.,
Importance of Cemented Layers in Inactij
Cosmochimica Acta, vol. 55, pp. 9
Botz, M.M. and Mudder, T.I., 1999. M
Impoundments, SME Preprint.
Littleton, CO, 8 pp..
Barfield, B.J., Warner, R.C.,jmi
Dis^^ed Lands,
Brown,
Brown,
mtation and Potential
feochimica et
ion in Tailings
lallurgy, and Exploration,
lied Hydrology and Sedimentology for
tillwater, OK, 603 pp.
|h"ry Baseline Studies. In: Marcus, J.J., ed., Mining
of Mining on the Environment and American
\g, Imperial College Press, London, pp 337-338.
ce Evaluations. In: Marcus, J.J., ed., Mining Environmental
ng on the Environment and American Environmental Controls,
"London, pp. 476-496.
f, G.G., MahonjJfjJ., Gale, J.E., Dignard, S.E., Napier, W., Reihm, D., and Downing, B.,
J997. Apr^piri Used to Model Pit Filling and Pit Lake Chemistry on Mine Closure -
fly, Labrador, Proceedings of the Fourth International Conference on Acid
jjjainage, Vancouver, British Columbia, May 30-June 6,1997, pp. 256-275.
Campbell, G.S., 1974. A Simple Method for Determining Unsaturated Hydraulic Conductivity
from Moisture Retention Data, Soil Science, vol. 117, no. 6, pp. 311-314.
Chow V.T., 1964. Handbook of Applied Hydrology, McGraw-Hill, New York, NY.
D-27
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
Clark, C.O., 1945. Storage and the Unit Hydrograph, Transactions of the American Society of
Civil Engineers, vol. 110, pp. 1419-1446.
Davis, G.B., Doherty, G., and Ritchey, A.I.M., 1986. A Model of Oxidation in Pyritic Mine
Wastes: Part 2: Comparison of Numerical and Approximate Solutions, Applied
Mathematical Modeling, vol. 10, pp. 323-329.
,ffi,..
Doyle, G.A. and Runnells, D.D., 1997. Physical Limnology of Existing .Mine Pitdlakes, Mining
Engineering, vol. 49, no. 12, pp. 76-80.
Freeze, A., and Cherry, J., 1979. Groundwater, Prentice-Hall,"Inc., Erl
Garvie, A.M., Bennett, J.W., and Ritchie, A.I.M., 1997/< Quantifyi|gxme S
the Sulfide Oxidation Rate in a Waste Rock Dumpvat Mfc^lyell, Tas:
of the Fourth International Conference
Columbia, May 30-June 6, 1 997, pp. 333-349.
Geo-Slope International, Ltd., 1995. SEEP/W User's Manual, 1
Calgary, AB (cited in Newman et al., 199
Green, W.H., and Ampt, G.A., 1911. Studj
Through Soils, J. Agronomy Soc,
Hanna, T., Azrag, E., and Atkinson^.^1994.
Estimates of Ground Wat^felow t
Vancouv
Holtan,H.N.,1961. A Co,
Department of Agrin
Morton, R.E., 1919.° Rainfall I
•11%
Infiltrd
.blicai
:ernational Ltd.,
of Air and Water
of an Afpalytical Solution for Preliminary
"''Engineering, vol. 46, pp. 149-152.
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EPA Region X Mining Source Book
Appendix D — Effluent Quality
Knisel, W.G., Moffitt, D.C., and Dumper, T.A., 1985. Representing Seasonally Frozen Soil with
the CREAMS model, American Society of Agricultural Engineering, vol. 28, pp. 1487-1492.
Jacob, C. and Lohman, S., 1952. Nonsteady Flow to a Well of Constant Drawdown in an
Extensive Aquifer, Transactions of the American Geophysical Union, vol. 33, no. 4, pp
559-569.
Li, M.G., Aube, B., and St-Arnaud, L., 1997. Considerations in the use of Shallow Water Covers
for Decommissioning Reactive Tailings, Proceedings of the FoiAJnferriational
Conference on Acid Rock Drainage, Vancouver, British Colun^i||^!|^ 30-June 6,1997,
pp.115-130.
Lin, C-K., Trujillo, E.M., and White, W.W., III, 1997.
Geochemical Kinetic Model for Acid Rock Dr
International Conference on Acid Rock Draina^
June 6,1997, pp. 479-495.
Linsley, R.K., Kohler, M.A., and Paulhus, J.L.H., 1975? Hydn
McGraw-Hill Series in Water Resources
Inc., New York, NY, 482 pp..
rti,f ,. r iX *S^SP:&;.Jgfc
Qieeedings of tne^fmftjmw
r, British Colurnte, May 30-
Lopez, D.L., Smith, L., and Beckie, R.,
Kinematic Wave Theory, Prop
Rock Drainage, Vancouver.
McDonald, M.G. and Harbau
Gro^-Water
^
Mehling, P
Delay,
yineers, 2nd edition,
ering, McGraw-Hill,
in Waste Rock Piles Using
Conference on Acid
iO-June6,1997, pp. 497-513.
Three-Dimensional Finite-Difference
Survey Techniques of Water Resources
I.S., 1997. Blending and Layering Waste Rock to
feneration: A Case Study, Proceedings of the Fourth
Wd Rock Drainage, Vancouver, British Columbia, May 30-
MNEWMMj), Series of four reports: Literature Review, User's Guide,
Application ofljKEWALL to Three Minesites, and Programmer's Notes and Source
ette, Mine Environment Neutral Drainage Program, Ottawa, Canada.
'/
, N.M., 1994. An Empirical Technique for Predicting the Chemistry of
T, ^^,— from Mine-Rock Piles, International Land Reclamation and Mine
-Drainage Conference and Third International Conference on the Abatement of Acidic
Drainage, Proceedings of a Conference held in Pittsburgh, PA on April 24-29, 1994,
U.S. Bureau of Mines Special Publication SP-06A-94, pp. 12-19.
Morin, K.A. and Hurt, N.M., 1995. MINEWALL 2.0: A Technique for Predicting Water
' Chemistry in Open-Pit and Underground Mines, Proceedings of the Conference on
D-29
-------
EPA Region X Mining Source Book _ Appendix D — Effluent Quality
Mining and the Environment, Sudbury, Ontario, May 28-June 1, vol. 2, pp. 525-536
(cited in Bursey et al., 1997).
Newman, L.L., Herasymuik, G.M., Harbour, S.L., Fredlund, D.G., and Smith, T., 1997.
Hydrology of Waste Rock Dumps and a Mechanism for Unsaturated Preferential Flow,
Proceedings of the Fourth International Conference on Acid Rock Drainage, Vancouver,
British Columbia, May 30-June 6, 1 997, pp. 55 1 -565.
^
Orwinowski, M., 1997- Meso-Scale Characterization of the Geochemical and .Physical Processes
Responsible for Acid Rock Drainage, Proceedings of$he Fourth International
Conference on Acid Rock Drainage, Vancouver, Bn^h Cohimbia^May 30-June 6, 1997>
*' .^'j-Vv-.^V *!& *• £^ '-4? ,'
c >r*7 c o C t'-£^?f' w" jilF
Penman, H.L., 1963. Vegetation and Hydrology, Tecbjfin^oiBBient No. 53, Commo^ealth
Bureau of Soils, Harpenden, England. """ ""'
Perkins, E.H., Gunter, W.D., Nesbitt, H.W., and Review of
Geochemical Computer Models Adaptable for from Mine
Waste Rock, Proceedings of the Fourth Rock
Drainage, Vancouver, British 199^^587-601.
'^fii^
Pettit, C.M., Tai, M.K., and Kirkaldy, J.I^f 997. to Geochemical
Assessment of Waste Rock, Pjnjjjeedings$fthe Fo^^^mernational Conference on Acid
Rock Drainage, Vancouverjjjfrifish Cojfffnbia, Ma»0-June 6, 1997, pp. 605-619.
Philip, J.R., 1969. Theory of Infflfration, Aj$j%^sfjir&ydroscience, vol. 5, pp. 215-296 (cited in
U.S. EPA, 1998a). N'
Pinder, G. ^mdrGiay, W., 1^77. Finite Element Simulation in Surface and Subsurface Hydrology,
Academic Press, New
Reisinger, R.W. and Gusefc^ J.J., 1998. Mitigation of Water Contamination at the Historic
Ferris-HaggartyfMoKf Wyoming, SME Preprint 98-111, Society for Mining, Metallurgy,
A and Exploration, lac., Littleton, CO, 6 pp.
Richardson, C.W. and Wright, D.A., 1984. WGEN: A Model for Generating Daily Weather
Variables, U.S. Department of Agriculture, Agricultural Research Service, ARS-8.
-*•%*
Robertson, W.D., Blowes, D.W., and Hanton-Fong, C.J., 1997. Sulfide Oxidation Related to
?f Water Table Depth at Two Sudbury, Ontario Tailings Impoundments of Differing
Physiography, Proceedings of the Fourth International Conference on Acid Rock
Drainage, Vancouver, British Columbia, May 30-June 6,1997, pp. 621-630.
Schroeder, P.R., Dozier, T.S., Zappi, P.A., McEnroe, B.M., SjostromJ.W., and Peyton, R.L.,
1994. The Hydrologic Evaluation of Landfill Performance (HELP) Model: Engineering
Documentation for Version 3, U.S. EPA, Office of Research and Development,
EPA/600/R-94/168b.
—- -
-------
EPA Region X Mining Source Book
Appendix D — Effluent Quality
Singh, R.N. and Atkins, A.S., 1984. Application of Analytical Solutions to Simulate Some Mine
Inflow Problems in Underground Mining, InternationalJournal of the Mine Water
Association, vol. 3, no. 4, pp. 1-27.
Soil Conservation Service (SCS), 1985. National Engineering Handbook, Section 4, Hydrology,
U.S. Government Printing Office, Washington D.C.
L*L
Steffen, Robertson and Kirsten (SRK), 1992. Mine Rock Guidelines, Design and Control of
Drainage Water Quality, Report No. 93301 prepared for the Sastchewan
Environmental and Public Safety Mines Pollution
Saskatchewan, Canada.
Swanson, D.A., Kempton, J.H., Travers, C., and Atkinsji
Seepage from Waste-Rock Facilities in Dry Cli\
Mining, Metallurgy, and Exploration, Inc., Littl
U.S. Army Corps of Engineers (COE), 1987. HEC-1
Methods, Inc., Waterbury, CT.
Albert,
Package, Haestad
U.S. Environmental Protection Agency,
Zone: Compilation of Simple Math
Management Research Laborato:
U.S. Environmental Protection Agj
Zone: Application ofSele(
Management Research ijporatory,
Vick, S
Voss, C.I., 198
i, and
1998
Rate in the Vadose
ational Risk
128a.
>Jf l99Sb^stimatioff Infiltration Rate in the Vadose
,, Volume II, National Risk
600-R-97-128b.
*of 'Tailings Dams, BiTech Publishers, Ltd.,
mUfation Model for Saturated-Unsaturated, Fluid-Density-
with Energy Transport or Chemically-Reactive Single-
U.S. Geological Survey Water-Resources Investigations Report
rD.W., Frind, E.G., and Ptacek, C.J., 1996. Sulfide Mineral Oxidation
SubsequejjiReactive Transport of Oxidation Products in Mine Tailings
Jmpoundmejli—A Numerical Model, Water Resources Research, vol. 32, pp. 3173-
D-31
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Region 10 Mining Source Book
Appendix E- Wastewater Management
1.0
2.0
3.0
4.0
5.0
6.0
Table of Contents
GOALS AND PURPOSE OF THE APPENDIX E-l
MINING WASTEWATERS E-l
OVERVIEW OF MINING WASTEWATER MANAGEMENT , E-2
POLLUTION PREVENTION A. .,Jff E-3
5.1.2
5.1.3
ACTIVE TREATMENT OF MINING WASTEWlpRS .. &3
5.1 Metals Removal ^gf!f:tf||li;&> y/E-3
5.1.1 Chemical Precipitation M •&{ '^\$^:^^^-^j?E-4
5.1.1.1 Hydroxide Precipitation^^^,^ ~^|fPp9%'' _ E_4
5.1.1.2 Sulfide Precipitation . >-¥?T E-6
5.1.1.3 Coprecipitation E-6
Ion Exchange ^pf. .V. E-7
Reverse Osmosis ^ ?i|L J^C E-7
5.1.4 Carbon Adsorption ... ^ * E-8
5.1.5 Biological .' E-8
E-9
52.1 E-9
5.2.2 E-10
5.2.3 Sulfur Diox;
5.2.4 BiologicaJ^eltmerr
5.2.5 Natural ippradatio:
. Solid-Liquw^^»ation
iud8e
5.2
E-10
E-ll
E-ll
E-ll
E-13
ING WASTEWATERS E-13
w
lologies E-14
E-15
ystems at Metal Mines E-15
TREATABILIW TESTING E-17
7.1 Labor«ry Testing E-17
,7.2 Pirfcale Testing E-18
/ATER DISPOSAL E-19
Surface Water Discharge E-19
Land Application E-19
Evaporation/Infiltration E-20
Underground Injection E-20
E-i
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Region 10 Mining Source Book
Appendix E - Wastewater Management
9.0 STORM WATER MANAGEMETN AND BEST MANAGEMENT PRACTICES . E-20
10.0 WASTEWATER MANAGEMENT KEY ISSUES E-21
11.0 REFERENCES E-22
LIST OF TABLES
E-2
Table E-1. Summary of Mining Wastewaters
Table E-2. Example Passive Treatment Facilities at Met|pMines
Table E-3. Pilot-Scale Treatment Design M ,<#/ ... .:.-..". E-19
*S». *;'&£&«»- '
LIST OF FIG
Figure E-1. Solubility of metal hydroxides and
E-5
E-ii
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Region 10 Mining Source Book
Appendix E - Wastewater Management
1.0 GOALS AND PURPOSE OF THE APPENDIX
The goal of this appendix is to provide an overview of mining wastewater management
and identify information related to wastewater management that should be included in EISs and
NPDES permit applications for mines. The more specific goals for this appendix include:
• describing typical wastewater streams at mine sites, including process wastewaters,
mine drainage, and storm water;
• describing approaches that can be used to manage waste stre
• presenting EPA's expectations for the level of dejajl
• EPA's expectations for the level of analysis n<
permitting, and sound decision-making.
'A
Appendix E is intended to be used in conjunctil
book to which the reader is referred for more detailed ir
Appendix A, Hydrology, Appendix B, Receiving Waters*
Waste Rock and Tailings, Appendix D, Effluent Qualit
and Appendix H, Erosion and Sedimentation.
2.0
first step in d
the oppo:
Book, wjpgwaters
procejSnyater, or storm
d
In con
manage
sof wa
proposal, and
disclosure,
;r appendices fnJffis
XpV;* :-.-fj
Relevant appendices include
, Characterization of Ore,
I Waste Management,
Managing wastewater at a mine site
methods, water and mass balance develop:
natural waters and wastewaters at a siteJjies;
waters that are not affected by the m\nifg procei
been affected by the mining proces^np must,
release and/or transport contami^^^ The
activities are described in the fcJIIwing se
ig and treatment
lanners must evaluate the
3). Natural waters are those
•astewaters are waters that have
ecause they have the potential to
aters associated with mining
wastewaters associated with a mine site is an important
dagement scheme, especially in regards to maximizing
lion 4.0). As discussed in the main text of the Source
jjh mining facilities are typically classified as mine drainage,
ible E-l provides a description of the types of mining-related
with these classifications and some regulations that are
>n 2.0 of the Source Book provides more detail on the regulations
and how they relate to NPDES permitting.
E-l
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Region 10 Mining Source Book
Appendix E - Wastewater Management
Table E-l. Summary of Mining Wastewaters
Type of
Wastewater
Description
Applicable Regulations -1
Mine Drainage
Any water drained, pumped, or
siphoned from an active mining
area, such as mine adit discharge
and open pit mine waters.
Subject to effluent limitation guidelines
at 40 CFR 440, which limit discharges of
pH, suspended solids and nagtals.
Provides for stoirn exempfibns.
Process Water
Mill effluent, tailings
impoundment/pile discharge or
seepage, leach pile runoff/seepage,
leach ponds.
to e:
mum
No. 152J
548 for
arges
ition guidelines
bination of y
uiretnants
11!!'
Storm Water
Associated with
Industrial Activity
Storm water discharges directly
related to manufacturing,
processing, or raw materials
processing; includes storm wat
runoff that contracts waste
overburden, or tailings d;
not combined with mijplarainagi
process water.
T permit regulations, including
eline general permit and
it; see FR Volume 63,
998, pp. 42533-
ent listing of covered
,'•. .•-"}*•*'.•
1- Wastewaters proposed for dischar||fti>•'wateny
CFR 122), including compliance wjlfevater qi
TOie U.S.
stand;
subject to the NPDES regulations (40
It is/important to
npk
»pl
must
(for
necessary, etc.):?
rock
,ze eacr^^^ptetewater to determine: (1) regulatory
icess wa^^^^'subject to "no discharge" restrictions which
;water management), and (2) potential management options
use of wastewaters, to determine if treatment is
it to characterize the potential for production of acid
atioiiSf naturally occurring pyrite and other sulfide minerals in
mines, waste rock dumps,, and tailings impoundments can produce acid water that contain
elevatedlevels of metals^ffaiefand total dissolved solids. The mechanism of ARD production
is described in AppendixP -Solid Waste Management. ARD testing is discussed in more detail
in Appendix C -Characterization of Ore Waste Rock and Tailings. Wastewaters should be
characterized in terms of both flow and chemistry.
Wastewater proposed for discharge from the site (effluent) might also require whole
effluent toxicity testing . Characterization of effluent quality is discussed in detail in Appendix
D - Effluent Quality. Management of mining wastewaters is discussed in the following sections.
3.0 OVERVIEW OF MINING WASTEWATER MANAGEMENT
As well as characterizing the chemistry of the wastewater, successful wastewater
management requires a thorough understanding of water flow and the site water and mass
E-2
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Region 10 Mining Source Book
Appendix E - Wastewater Management
balance. Decisions on water management practices and facility designs must be made based on
the water balance. Historically, mines have found it difficult to predict facility water balances.
For example, there have been several cases in Region 10 where no discharge of process water
was predicted by the mine operator based on initial water balances that were later found to be
inadequate (and a discharge was required). Therefore, EPA recommends a conservative
approach to predicting flows taking into account all site development, operational, closure, and
post-closure/reclaimed conditions and considering seasonal climatic fluctuations. See Appendix
A - Hydrology for more information related to the development of a water balance?
Mine operators typically have a range of different ofioptions for wastewater management.
These options are described in the following sections. Section 4.0 briefly discusses options for j?
source control and re-use. Section 5.0 provides a detaile£Eiscussioivof active \*§gstewater t rf
treatment technologies and Section 6.0 describes passi^|reatment options. Section 7:0 presents
approaches to performing treatability studies. Section ^p;jdjs£uisies wastewater disposal 'options.
Section 9.0 discusses storm water management.
4.0 POLLUTION PREVENTION
The volumes of mine waste waters
by pollution prevention practices. Polluticp|preveni
reuse. Source control involves minimizpl the voRie
generated at a site. For example, contajkination^surfj
surface flow around waste rock tailu^'impouni
prevent contact with pollution
Waste Management for
approach to^nimizing ths^for wast
re-use/r§
it and dis||«|sal should be minimized
splice control, recycling, and
contaminated water
Re
benefits throu
prevention
loac
wast
This adults in lower ca
an«^imates where wa
led water.
-,
may be prevented by routing
ents or capping these waste units to
d seepage (see Appendix F, Solid
in practices for solid wastes.) Another
>sal is to maximize the potential for water
ter produced by a mine clearly provides environmental
face and ground water. In addition, pollution
devl
opera^nal costs. In wet climates, for example, the costs of
§ls disposal can be reduced because less treatment is required.
nditures for treatment and, potentially, lower energy costs. In
ly costs are high, operational costs can be reduced by using
yHsm
operators to use pollution prevention approaches to limit wastewater
need for disposal. EPA expects mine operators to demonstrate that they have
Implemented all potential pollution prevention options for wastewater in
Sftheir plans of operations.
5.0 ACTIVE TREATMENT OF MINING WASTEWATERS
Treatment of mining wastewaters may be necessary in order to reuse the water hi
processing and/or to comply with NPDES permit effluent limitations. This section discusses
E-3
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Region 10 Mining Source Book
Appendix E- Wastewater Management
some treatment technologies that may be used for these purposes. Section 5.1 discusses
treatment for removal of metals, Section 5.2 discusses cyanide treatment, Section 5.3 discusses
solid-liquid separation, and Section 5.4 discusses sludge removal. The technologies discussed
may be used separately or in combination to meet treatment goals. Section 7 discusses
treatability testing and other considerations related to selecting a treatment technology or set of
technologies.
5.1 Metals Removal
This section describes technologies that may be used^o remqj
wastewaters. The discussion is focused on the more conuHiitJiy used
*. -:*£ ??$$''''
technologies. Biological techniques are also discussed, Jpiough the;
limited application. Since metals cannot be destroyed, Jle treatm
the metals from the wastewater.
from mining
chemical
The selection of a treatment technology depends
wastewater and treatment goals. Understanding the p.
streams is critical because these parameters largely determine
of metal species. Mine drainage typically is Smith"
general negative correlation between metals
magnitude. Under oxidized, low pH com
salts. Treatment technologies for mimnjjpvastewi
these soluble salts to less soluble hydride or de saltiSRiiidh then can be removed by
physical means (i.e., settling, precjra^on/cla^pcation o|piltration). In characterizing
iting
•acteristics of the
ite of various wastewater
and, hence, mobility
4) illustrated a
iktends over 5 orders of
highly soluble sulfate
adjustment to convert
iys important to understand both the
>nditions typically determine this
wastewater and selecting treatm
soluble and total concentratio
balance.
5.1.1
Chemic
the physical
sedimentation. Che
first converted to an ins
precipitated as insoluble,§ylroxides or sulfides), then agglomerated into large, heavy particles
andremoved by physical means such as sedimentation/clarification, filtration, or centrifugation.
This technique provides a well-developed and effective treatment process for removing a wide
range ;of heavy medals'from wastewater.
ater treatment involves the addition of chemicals to alter
and Impended solids and to facilitate their removal by
Station typically is a two-step process in which soluble metals are
rm (i.e., dissolved heavy metal ions may be chemically
Successful precipitation of metals depends primarily on two factors:
• The addition of sufficient anions to drive the chemical reaction toward precipitation
of the solute; and
• Physical removal of the resulting solid phase from the wastewater.
The three most common methods of chemical precipitation (hydroxide precipitation,
sulfide precipitation, and coprecipitation) are discussed in the following subsections. Other
E-4
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Region 10 Mining Source Book
Appendix E- Wastewater Management
precipitation processes have been developed (e.g., insoluble starch xanthate process) but are not
in widespread use. All these processes require subsequent solids-liquid separation (Section 5.3)
and sludge removal (Section 5.4).
5.1.1.1 Hydroxide Precipitation
Hydroxide precipitation is the conventional method of removing heavy metals from
wastewater. Normally, this process involves the addition of caustic sodf or limfgp-adjust the
solution pH to the point of minimum solubility. The total residual meta|,;|onoentration is a
complex function of pH, with the lowest residual metal con(§|ntration|^^pi^ at some
optimum pH value (Figure E-l). The residual concentratijpffll incre^S^|||h.e pH is either^
lowered or raised from this optimum value. """^
Hydroxide precipitation is simple, effective, an
to the high solubilities and amphoteric properties of c
(Amphoteric metals act as both acids and bases and will
solutions.) In addition, the minimum solubilities for
and the precipitation of individual hydroxides occurs
For these reasons, the maximum removal efficiej
single precipitation pH (Bhattacharyya et al.,
multiple stages of precipitation at differenyffiHlevel
precipitation alone may not be adequatej|y achievejbmi
effluent discharge limits based on aquajpc life qualr
metals). Therefore, additional treajiiellt via of the
sections or use of more effectivej||pfless practi
necessary.
cticed, but ha^jmltations due
hydroxides (Kjm^rWl).
excessively acid or alkaline
cur at different pH values
ge (Figure E-l).
be achieved at a
ig upon treatment goals,
Treatment by hydroxide
foals (e.g., NPDES permit
ia may be very low for some
ler technologies discussed in the next
, treatment technologies may be
met
, estirris
ations bl
lydroxide precipitation can be predicted;
howeverfS
always be
of several ordel!
Section 7.CL
efficienc
Sulfide PrecipM
gtal removal by precipitation as metal hydroxides should
simplifying theoretical solubility data can lead to errors
1990). For this reason, and other reasons discussed in
al to predict wastewater-specific metals removal
JlH'
Sulfide preemption is an alternative precipitation method that offers advantages due
to the MfguZtivity of sulfides with heavy metal ions and the very low solubilities of
. broad pH range. Metals can be removed by sulfide precipitation to
mcentrations at a single pH (Figure E-l). Consequently, sulfide precipitation
treatment alternative when hydroxide precipitation is not possible, or effective in
removing metal ions to the low concentrations that may be required to meet water quality-based
effluent limits . The extent to which metal sulfides precipitate is a function of pH, type of metal,
sulfide dosage, and the presence of other interfering ions (Bhattacharyya et al., 1981).
The current methods of sulfide precipitation - the soluble sulfide method and the
insoluble sulfide method - differ in the technique of delivering sulfide ions. The soluble sulfide
E-5
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Region 10 Mining Source Book
Appendix E - Wastewater Management
method involves adding Na2S or NaHS solutions to the wastewater. The insoluble sulfide
method uses a sparingly soluble metal sulfide, such as FeS used by the proprietary Sulfex method
(Scott, 1979). Some sulfide precipitation occur naturally in conventional hydroxide
precipitation systems because low levels of sulfides are often found in the untreated wastewater.
E-6
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Region 10 Mining Source Book
Appendix E- Wastewater Management
3 4 5 6 7 8 9 10 11 12 13 14
Igure E-l. Solubility of metal hydroxides and sulfides.
E-7
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Region 10 Mining Source Book
Appendix E - Wastewater Management
The current sulfide precipitation methods have several drawbacks. The addition of NaS
usually produces colloidal or very fine particles, which settle poorly and should be treated with
coagulants and flocculants before final clarification. The use of FeS requires an excessive
amount of reagent and produces a large amount of sludge because of the addition of iron (Kim,
1981). To minimize these problems, calcium sulfide can be used as the sulfide source. The
addition of CaS (as a slurry) produces precipitates that settle easily; the increase injhe sludge
volume is minimal because calcium is mostly dissolved in the wastewater after reaction (Kim,
1981). /*, , */
,> ,** "r
jVg ' < >/r f ^
One example of the use of sulfide precipitation is $h.e,iRed Dog Mm&j, Derated by ^
Cominco, in Alaska. The Red Dog Mine implemented sulfide precip^ationitOTRieet effluent^^
limits for cadmium that could not be consistently achieved with the^existing^hySfo^ide, ^
precipitation system. The currently approved plan of o^^^onslfor the proposed Seosiagton
Project includes use of sulfide precipitation for mine
are
iron sulfate
and arsenic
5.1.2 j«Ion Exchange
5.1.1.3 Coprecipitation
"Coprecipitation" generally describes a
precipitants in a reaction vessel that serves
use of either single precipitant. Chemical
wastewaters include sulfides, hydroxide.
comparison with the lime and the su]fijjp precip:
consumes less of the expensive
low sulfide solubilities. Thus,
limits at a cost less than that,
precipitation^ystem can
1981). The^atest di
more than
itment.
bines two
efficiency beyond the
used for mining
ttages of Coprecipitation, in
that Coprecipitation
"ectively removing metals that have
>r compliance with stringent discharge
!e. A conventional hydroxide
:e hydroxide-sulfide Coprecipitation (Kim,
coprecapteifion is probably the need to maintain quantities of
site. At East Helena, Montana, ASARCO uses the term
pe water treatment at its' smelter site. ASARCO adds
density sludge (HDS) process to coprecipitate iron
quality criteria.
The ion exchange process is essentially similar to the adsorption system in which the
wastewater is passedlhrough a resin (solid porous particles with reactivesurface "sites"). The
metal ions in the wastewater that have a stronger affinity for the reactive (adsorption) sites than
the attached group, are exchanged with the attached group that results in removal of the metal
ions from the wastewater. . The metal-loaded resins must periodically be regenerated by the
introduction of a solution of concentrated ions, such as sodium chloride, which displaces the
removed metals from the exchange sites. The regeneration stream, rich in displaced metals, must
then be treated or disposed.
The efficiency and performance of an ion exchange system generally depend on pH,
temperature, and pollutant concentrations. The highest removal efficiencies are most often
E-8
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Region 10 Mining Source Book
Appendix E - Wastewater Management
observed for polyvalent ions (EPA, 1979). Ion exchange systems usually require some degree of
pretreatment or preconditioning (e.g., coagulation and filtration) of wastewater to reduce
suspended solid concentrations, which tend to clog ion exchange resins.
Application of ion exchange technology has historically been limited, by economics and
resin exchange capacity, to the treatment of water containing 500 mg/L or less of total dissolved
solids (IDS) (EPA, 1979). The ion exchange process has relatively high operatingypid
maintenance costs. At higher IDS levels, calcium and magnesium removal predominates,
resulting in the need for frequent regeneration, and large volumes of regenerant to dispose. The
technology has been most commonly applied to water purifyation and.selective removal of
heavy metals (i.e., only soluble, ionized metals) and metejfipl&de complexe% from industrial ;
wastewater. For example, ion exchange is used by, ele^oplatersdi^hargi^gto*|mblicly owfled
treatment facilities to reduce high concentrations of arsjff c, bariu^c^dmiiim^^'clrojmium, *W
copper, cyanide, lead, iron, manganese, mercury, selen^^^il^fand zinc. EPA Iciiows of no
active mines in Region 10 where ion exchange is curre:
in-flow vo!
depend
For examp]
fouling^
genei
wastSwater must be me
5.1.3 Reverse Osmosis
Osmosis is defined as the spontaneous
more concentrated one through a semiperme
utilizes semi-permeable membrane materi
of ions (including metals). In reverse
permeate (i.e., clean water) to diffuse
wastewater into two components:
and a concentrated residue (i.e., j£pETstre;
The reverse osmosis unit produlJla brine
ie that and
tialT
used to treat wasfewater.
lute solution to a
83). The process
y slow or stop the passage
the wastewater, forcing the
t .
e membral
necessary. G
:everse osmosis divides the
itable for reuse/recycle or discharge ,
all of the original pollutants.
b about 10 to 50 percent of the treated
part, the volume of brine stream will
volume increases with TDS concentrations).
cess that cannot withstand varying input conditions.
ions (e.g., calcium, manganese, iron) may cause
isult, pretreatment (e.g., filtration and carbon adsorption) is
ie pH, temperature, and suspended solids levels of the
ior to reverse osmosis treatment in the interest of efficiency and
:r7
jis is highly effective in removing metals to very low levels and it is one of
^ Jat will also reduce TDS in the waste stream. TDS concentrations of 100
~~n~~j be achieved with single-pass systems. Two or more units operated in series can
lower TDS concentrations (10 to 25 mg/L). Historically, metals removal by reverse
osmosis has been limited by high capital costs, intensive maintenance requirements, and high
energy costs. EPA is not aware of any active mines in Region 10 which currently use reverse
osmosis to treat wastewater.
5.1.4 Carbon Adsorption
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Region 10 Mining Source Book
Appendix E - Wastewater Management
In carbon adsorption, wastewater is typically pumped through one or more vessels
containing activated carbon. Organics and some metals are adsorbed onto the carbon. As with
ion exchange, the carbon must be periodically reactivated or disposed and replaced with fresh
carbon. Carbon adsorption is most commonly used to remove organic materials in tertiary
wastewater treatment. It has been observed that some incidental metals removal also occurs in
such systems. Most probably, this removal is the result of organic material adsorbed on the
carbon degrading under anaerobic conditions and producing sulfide ions. These ions then form
insoluble sulfide salts with metals in the wastewater. The resulting insoluble panicles are then
trapped in the carbon structure and essentially removed by filtration. TJl||}rQ||^ Creek Mine
(Hecla) in Idaho currently uses carbon adsorption followingj:|ydroxidj^^^tation for mercury
removal.
5.1.5 Biological Treatment
Certain biological processes have been document!
removal of metals from mining process effluents. BicJppicaT
addition of bacteria which promote biosorption of toxic heavy:
process effluents and biodegradation <
oxidation/reduction, filtration, and bioaccum
biological treatment, which range from co
Biological treatment processe
including cost effectiveness, low
with effluent-receiving streams,
be required to meet effluent
processes ap^ensitive
5.2.4, the Homestake
metals from the effluent
'- '."•• - V^" ^v.;.^:^1 <-••.
bacteria for
the microbes acH
ive technologies for the
systems are based on the
suspended solids from
precipitation,
te various types of
ied reactor systems.
IvantaiiPPFer chemical treatment methods,
fbn, flexi||jl design characteristics, compatibility
formate. However, additional treatment may
jd pjQ^p&tment may be required since biological
fnal fluctuations. As discussed in Section
;nt to destroy cyanide as well as removing
IBS in Canada are evaluating the use of sulfide-reducing
mechanism to chemical sulfide precipitation, except
5.2 Cyanide Des
'•* :<%*! .'• 's^ ^s --j'gr
7 Cyanide is used at" stnie mines during ore processing operations. Cyanide has the ability
to: create highly solubleiihetal complexes. For example, the most common process for the
recovery of gold is that of cyanidation, in which gold is leached from the ore by a weak cyanide
solution (usually NaCN). Cyanide is also used as a flotation reagent to suppress iron during
flotation processes.
With the use of cyanide in ore processing comes the need for additional measures to
provide for chemical destruction of cyanide and cyanide-metal complexes in process waters.
Cyanide exists in several forms in mine process wastewater, including free cyanide, cyanide-
sulfur compounds (thiocyanate) and metal-cyanide complexes. Metal cyanide complexes occur
as stable iron and cobalt cyanide complexes and the weak acid dissociable (WAD) metal
complexes of cadmium, nickel, zinc, and copper. Cyanide breakdown products such as
ammonia, nitrites, and nitrates may also be present. As with metals removal, it is important to
E-10
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Region 10 Mining Source Book
Appendix E - Wastewater Management
determine the form of cyanide and cyanide-metal complexes present in the wastewater. The
selection of a cyanide destruction technology will depend upon the characteristics of the
wastewater and treatment goals.
The mining industry uses a number of treatment processes destroy cyanide. This section
describes the more prevalent technologies, including alkaline chlorination, hydrogen peroxide
treatment, and sulfur dioxide/air treatment. Detailed information on the chemistry of cyanide,
technologies discussed in the following subsections, and other methods Jpr cyanide"treatment can
be found in Smith and Mudder (1991). The cyanide destruction process^ dis^filsed accomplish
two objectives: breakdown of the metal-cyanide bonds and^estructioS^^afiide. Depending
upon treatment goals, cyanide destruction may be followe^^f>recipn^^^OT*
-------
Region 10 Mining Source Book
Appendix E - Wastewater Management
cyanide to cyanate while in the presence of a metal catalyst such as copper, iron, aluminum or
nickel. Subsequently, the cyanate is hydrolyzed to form carbonate and ammonia (Knorre and
Griffiths, 1985). During the destruction of metal cyanide complexes by hydrogen peroxide,
liberated metals are precipitated as metal hydroxides. The required hydrogen peroxide dosage
depends on the WAD cyanide concentration in the waste water, the strength of the hydrogen
peroxide solution, and the rate of mass transfer of hydrogen peroxide to the wastewater (Roeber
etal., 1995).
Although more costly than chlorination, hydrogen peroxide tre
TDS to the wastewater since it reduces to water. Additionaljadvanta:
treatment is that iron complexed cyanides are destroyed aiMirietals
precipitation (although additional metals removal may sfl| be requi
5.2.3 Sulfur Dioxide/Air Process
Two patented versions of the sulphur dioxide/air
marketed by Inco and another by Noranda, Inc. (Smi
uses a mixture of sulphur dioxide (SO2), sodium sulfit
(Na2S2O5) and air within a controlled pH range t
Noranda process differs in that pure sulphur
not contribute
•ogen peroxide
'Ugh
In the Inco process, both free andjlbmplex
Hydrolysis of the cyanate results in^ej^rmatio^pf carbol
complexes are reduced to the ferroj||j^!jate andjimtinuo'
ferrocyanide salts of copper, niqpJPBr zinc
only after cyanide has been elin^Sted. N
percent of^influent miocyj^||yf|rels (S:
gtruction process include one
. The Inco process
meta-bisulphite
ital., 1995). The
required.
to produce cyanate.
de and ammonia. Iron cyanide
precipitated as insoluble metal
.e Incojfpbcess also removes thiocyanate, but
opejnrons will result in approximately 10 to 20
Her, 1991).
fed into a soliM|i0|^^Jurry td^
Subsequently,^
concentratioas,
iur dioxide or industrial grade liquid sulphur dioxide is
levels to 7.0 to 9.0 (Smith and Mudder, 1991).
y
s added at a rate which yields desired cyanide
X^;- fif
Advantages of the sulfur dioxide/air cyanide destruction processes are that all forms of
cyanide are removed and metals are removed through precipitation (although additional metals
removal may be required, depending upon treatment goals). Disadvantages include high reagent
costs, the potential for production of high levels of TDS in the effluent, and strict process control
is required.
5.2.4 Biological Treatment of Cyanide
Biological destruction of cyanide occurs by oxidative breakdown of cyanide and cyanide
complexes and subsequent chemical complexation (adsorption/precipitation) of free metals
within the biomass. The Homestake Mine in Lead, South Dakota, has successfully operated a
biological wastewater treatment plant since 1984. This plant removes cyanide as well as heavy
metals by maintaining an oxygenated wastewater environment for a short retention time to
E-12
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Region 10 Mining Source Book
Appendix E- Wastewater Management
adsorb the metals in the biomass or biofilm. Bioadsorption of the metals is similar to the vise of
activated carbon; however, the number and complexity of binding sites are much larger on the
biological cell walls (Whitlock, 1989). Five-year averages from 1984 through 1988 for effluent
from the Homestake wastewater treatment plant yielded removal rates of 94 to 97% for copper,
99 to 100% for thiocyanate, 96 to 98% for total cyanide, 98 to 100% for WAD cyanide, and 98 to
100% for ammonia conversion to nitrate.
Advantages of biological treatment include low reagent costs compared to other cyanide
destruction methods, all forms of cyanide, cyanide complexes, and ammima ar
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Region 10 Mining Source Book
Appendix E - Wastewater Management
flocculation, settling, and, if necessary, filtration. Flocculation, settling, and filtration are widely
used technologies in wastewater treatment. A thorough discussion of these technologies can be
found in Metcalf and Eddy, Inc. (1979). The following briefly summarizes these three steps:
(1) coagulation (the reduction of electrical repulsive forces on a particle's surface) and
flocculation (the agglomeration of particles through adsorption);
(2) gravity separation (settling); and
(3) filtration.
In the first step, chemical coagulants are added to
conditions of concentration, pH, mixing time, and tempi
adsorb onto the coagulant and agglomerate to form flocs>||&gglomeraji^i?
diameter of the metal particles, which increases their selling rate.j
~ :^r^n.-^?. ^"^ .•-!*'*
is induced by particle contact, flocculation generally o Jj
agglomeration, the floes are pumped to a clarifler, whet
settling (step 2). The particles settling within the cla
be removed for additional treatment or disposal (see
in a pond or series of ponds.
controlled
compounds**
-•.if '-•*'. *'*'.:••£• -1^
spriate time is permitted for
i underflow sludge that must
ately settling may occur
A common approach currently beii
(HDS) process. The HDS process is simil
process, however, a portion of the settledjfolids in JR cl
convj
sites ii|pe' high-density sludge
tralization and settling
ycled back to the
ng of recycled sludge and lime
precipitation cell where the sludge is^aglin mixejdpwith lin|
yields a high density sludge consisjflglbf relajpliy largejjitticles that settle quickly. The HDS
process has two advantages overjfipventior
increases the sludge density jvh||l; in turnj
sludge requiring
*SS^K
To f«iiip«ahance
ime trealpent and settling. First, recycling sludge
ts insignificant reduction in the volume of
jlhe recirculated sludge results in additional
?ase metals removal efficiency.
metals from wastewater, a third step, filtration, is
•ge limits. Filtration removes fine particles that lack
er time, solids will build up on the filter necessitating the
applied if necessary to inget effl
sufficient sizeCd»settle e^sti
removal of accumulated ^pfi|s%:The removal process, termed backwashing, may be done on a
batch, or continuous basi^|l|ejpHiing on the design of the filter.
>;
Early filters used sand as a filter medium and operated in a down-flow mode. That is,
water flowed down through a sand bed to an underdrain system which collected the filtered
water. Backwashing was accomplished on a batch basis by forcing water upwards from the
bottom of the filter, with the filter off-line, with the accumulated material allowed to overflow
the filter surface. Newer filters may operate in the upflow mode, with accumulated material
removed ion a continuous or semi-continuous basis. Newer filters also may contain two or more
filtration materials (e.g., anthracite coal or garnet sand) which, through density differences,
classify into distinct layers. Each of these media layers provides a different level of porosity,
allowing filtration to occur throughout the filter rather than just on the surface. This provides a
greater storage capacity for removed materials, allowing longer runs between backwashing. Sand
filters are less expensive to construct, but media filters are capable of removing smaller size
particles. Determination of which filtration type, if any, is needed at a particular mining site will
E-14
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Region 10 Mining Source Book
Appendix E- Wastewater Management
be based on the characteristics of the wastewater and the effluent discharge limits that apply.
Filtration has not been widely applied to date at mining facilities but may need to be considered
in the future to meet low effluent limits based on water quality criteria. The Red Dog Mine
(AK), for example currently uses sand filtration prior to discharge from one of its' two treatment
plants. In Leadville, Colorado, sand filtration is used in a high density sludge process to treat
effluent from historic workings.
5.4 Sludge Removal
Chemical co;
Waste sludge removed from clarifiers is a liquid typically ranging frorff
suspension. Disposal will usually require some degree of dewatering?
methods of dewatering are belt filter presses or plate and frame fillfrp
dewatering is not generally practiced in the mining industry since sludges are
§ires management.
lercent solids ja
siornmon
—"«•"" •-"•* *-' ^ "%§?|fv- *'••'"'
of in tailings ponds. Other options for sludge disposal include backfill into mine voids and
disposal in an appropriate landfill. ; ;"y * 4
iposed
Selection of sludge management techniques depends upcfeAfriSfblume and composition of
the sludge and regulatory requirements. Sludge is dominated ty the coagulant
added to the system (e.g., lime), but will and o||er insoluble constituents
removed from the wastewater. The on the pH of the
sludge remaining high. Disposal into a jWfings be advisable since the
more neutral pH conditions of the imp^fcdmen^ay causl|pelils to redissolve into supernatant
waters.
Unlike many other wjistiprom
from wastj|||ter treatmenA»es are n
-------
Region 10 Mining Source Book
Appendix E - Wastewater Management
water quality through a variety of physical, chemical, and biological processes that include
acidity reduction and concomitant alkalinity increase (either by bicarbonate addition, sulfate
reduction, ferric iron reduction, or a combination), metals removal (by hydroxide or oxide
precipitation , plant uptake, sorption onto organic materials, or sulfide precipitation),, and sulfate
reduction (by microbial action or gypsum precipitation). Studies of natural wetlands systems
receiving neutral to acidic metal mine drainage with high metals values have been useful for
understanding how passive systems function. Studies of natural wetlands in Colorado and
Minnesota found that they removed iron, chromium, cobalt, copper, nickel, and ^aSi with varying
efficiency that depended on influent water quality, residence time, wat^^nppiture, the
distribution of flow within the wetland cells, sorptive capacity of the j|^:j^g|^depth of removal
(Eger et al.,1993; Balistrieri, 1995; Walton-Day, 1996). ' t ^"
uptake
vegetation type,
^-.,-v.; '-'' •;£•
wetlands; several;;
evaluated
Passive treatment systems do not require routine main]
and are more cost-effective to operate over long time
seasonal fluctuations (e.g., cold temperatures, inc;
precipitation) and may be unable to consistently achieve
briefly describes three of the technologies most co
wetlands, anaerobic wetlands/bioreactors, and anoxic lunestom
6.1 Commonly Used Technologies/
:tO
ce, enejgy suppfylj
ever, they
caused by inc:
it limits. The next section
mines: aerobic
ms
Constructed wetlands we:
outwardly mimicked natural sy;
complex designs intended
process (e.gj^Brodie, 199
le, rather empirical structures that
Recently constructed wetlands have
:ffects at each step of the treatment
and Updegraff, 1997). Flow rates,
capacities, alkalinity production, and metal
y wetland size, flow path, substrate composition, and
Substrate compositions vary widely among constructed
" ., 1988; Howard et al., 1989; Gross et al., 1993) have
stone is commonly used as a substrate below the organic
matter to:add alkalinity, Ccraponly used plants include cattails (Typha spp.; the most widely
used wetland plant), Sphggyim, bulrushes (Scirpus spp.), sedge (Carex spp.), and algae
(Cladophord). Most plants are relatively tolerant of high metal concentrations and acidity but
thfjif vary in their ability to accumulate or take up metals from wetland waters and sediments
(elgl, Duggan et al., J992; Sengupta, 1993; Garbutt et al., 1994; Erickson et al., 1996). An
important effect ofewetland plants is their ability to stimulate microbial processes, add oxygen,
raise pH, and supply organic nutrients (Kleinmann, 1991; Wildeman and Updegraff, 1997).
Aerobic wetlands systems utilize oxidizing reactions to precipitate manganese and iron
oxyhydroxides that sorb selenium and arsenic from influent waters (Gusek, 1995; Wildeman and
Updegraff, 1997). These systems, which also can be used to remove WAD cyanide, operate most
effectively when influent pH exceeds about 5.5.
Anaerobic wetlands and bioreactors (facilities that have a cap precluding oxygen
infiltration) use bacterially mediated sulfate reduction to precipitate iron, copper, lead, zinc,
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Region 10 Mining Source Book
Appendix E - Wastewater Management
cadmium, and nickel as sulfide minerals and to reduce uranium and radium to insoluble forms
(Gusek, 1995; Wildeman and Updegraff, 1997). Bacterial action has the added benefit of raising
pH by producing bicarbonate alkalinity. Anaerobic systems can function with influent pH levels
of less than 2.5.
Anoxic limestone drains (ALD) are used to intercept ground water and direct it through a
buried bed of limestone. In recent years, ALDs have been widely used to pre-treat^.MD prior to
anaerobic wetlands treatment in order to add alkalinity in the form of bicarbonate 9cO3') that
improves effluent quality and extends the effective life of wetlands
add sufficient alkalinity so that effluent waters do not re-i
hydrolysis. In theory, the anoxic conditions maintained i
limestone without concomitant armoring by sulfates or
practice, however, aluminum hydroxide and gypsum (
eventually clog the drain (Skousen, 1991; Ziemkiewic:
flow over the drain and escape treatment. Consequent!;
flush precipitating minerals through the drain. The effecl
treatment option depends on influent water quality (S
function most efficiently when influent waters have m
(<2 mg/L), low ferric/ferrous iron ratios, dissolvi
and sulfate concentrations less than 2,000
Js5§i?S3*5B3"'^ ^^^^^J^^^^^^^JS^^^^fei.
1994).
6.2 Passive System Design
Important design factors JHifrassive
path, and residence time), of the
andmetalsJfcri.
water (I
constnii
intent is to
and ferric iron
tion of
991). In^
'
to
Sugh to
ALD as a passive
die etal., 1993). ALDs
:d oxygen contents
less than 25 mg/L,
Ziemkiewicz et al.,
lent sjpems include hydraulics (flow rate, flow
m rate of supply of carbon, temperature,
rents are determined from the influent flow,
Nairn, 1992). Sizing criteria for wetlands
developed by Hedin et al. (1994) and Hellier et al. (1994).
guideline for passive treatment systems that would be
it many metal mines in the western U.S.) where
ikely to operate at slower rates (Sengupta, 1993). Mean
Jemperature variations are other factors that affect the efficiency
influencing bacterial activity and wetland plant growth.
Their values!
constructed at"
biological
annual js^lperature;
of a njssive treatment
w I ,
The carbon SOUK and its replenishment are particularly important since carbon is a vital
snt required to ngpntain bacterial populations in anaerobic systems. In general, anaerobic
ave a projeg^jlfife of 20 to 100 years, after which the organic substrate will need to be
unestone drains have a projected life of 30 years before limestone
^present, it unclear how long aerobic cells will function properly; however,
metal loads, mineral precipitation may require replacement of substrate materials.
Consequently, passive treatment is not a "walk away" technology that will work as designed in
perpetuity. Despite their high front-end costs, the low maintenance costs (primarily periodic
sampling and substrate replacement) makes them an attractive post-closure option. Passive
wetlands systems also have the potential to provide habitat, however, the environmental impact
of such habitat must be evaluated (e.g., to demonstrate that terrestrial and aquatic animals
inhabiting the wetlands will not bioaccumlate metals).
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Region 10 Mining Source Book
Appendix E - Wastewater Management
63 Example Passive Systems at Metal Mines
Passive systems can be designed to treat runoff and seepage from waste rock dumps,
tailings piles, and spent ore heaps, and drainage from adits and historic mine facilities. The
technology was developed to treat acidic waters generated from abandoned coal mines in the
eastern U.S. and has gained widespread acceptance for this application (more than 600 passive
systems were constructed and operating in 1996; Gusek, 1998b). Metals levels in the low parts
per million or high parts per billion range are typically achieved. At coaj mmes^ffdic waters
contain high concentrations of sulfate, aluminum, iron, and manganesejS^fypother metals.
Only recently has passive treatment technology been used tolreat waters
draining from metal mining sites. These technological applications
In addition to high concentrations of TDS and sulfate, racial mine a variejpof
metals in moderate to high concentrations. The presen|pof nume
the geochemical system design.
is shown in Table E-2. In
employed at several other
;tions. The mines in
ongoing
Several examples of the use of passive systems at
addition to the facilities shown in Table E-2, passive
inactive or historic sites described in the references ol the previ
Table E-2 and referenced in the previous histori
remediation projects. The only active mine of thai
to meet NPDES permit effluent limits is
challenge to using passive systems is
operating conditions. At present, pajjsjil systeraflppear iilllPlPviable alternative only under
limited conditions or when used irjk^n%inatiggpwith other treatment approaches.
t'SrtS'
sing passive treatment
uri. Overall, a major
, at all times, and under all
ent Facilities at Metal Mines
Passive Technologies
Used
Effluent
Characteristics
Wheal Jane, UKS
UndergroundjlSii-Oai
Inactive. idPF
3,500
u = 1.05mg/L;
i.l mg/L
Anaerobic cell -* ALD
-»Aerobic Cell -»
Anaerobic Cell -* Rock
Filter
Not available.
We&Fork,MO
Underground Pb- Zn
gpm, pH = 7.9; Pb =
0.4 mg/L; Zn = 0.36 mg/L;
Cu = 0.037 mg/L
Settling Pond -»
Anaerobic Cell -»Rock
Filter -» Aeration Pond
pH = 7.2; Pb = 0.04
mg/L; Zn = 0.07
mg/L; Cu = <0.008
mg/L.'
Ferris-Ha^arty, WY
Underground Cu
Abandoned
20 to 480 gpm; pH = 4 to 7;
Cu =2.0 to 6.5 mg/L;
Significant seasonal
variations.
Pilot Anaerobic Test
Cell
pH = neutral; Cu =
0.05 mg/L.
Sources: Wheal Jane: Cambridge, 1995; West Fork: Gusek et al., 1998a; Ferris Haggarty: Reisinger and Gusek,
1998.
E-18
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Region 10 Mining Source Book
Appendix E- Wastewater Management
7.0 TREATABILITY TESTING
Each individual mining wastewater is a unique blend of metals, hardness, pH, IDS, and
trace components. Under actual production conditions, the composition will continually vary to
at least some degree. The complexity of the wastewater matrix limits the extent fcMynich
experience (e.g., treatment effectiveness) gained at one facility can be directly applied to another.
Although theoretical chemistry may indicate how
complex matrix that exists at a specific site may limit the^^lcability
actual conditions. Consequently, a treatability study isjpuired pri ^
design. Prior to treatment system selection and design essent^to char
wastewater and identify desired effluent quality It is critical"
characterization and wastewater samples utilized in are
range of operating conditions that will occur during the
Also, a site-specific analysis showing that the treatme
regulatory or permit limits under the range of operating conditil!
and permitting. Appendix C, Characterization <
D, Effluent Quality provided additional
treated, the
jstieal data to
stem
•ater
ve of the
and/or after closure.
of consistently meeting
for NEPA analysis
'ings and Appendix
rization.
fitjr
jcessary to select a
Ety testing provides valuable
The use of laboratory and pilot-sjile treat
processes) that will consistently meeUpeataent
design data that can reduce capita^^^tmen^Sisure greJpSr reliability, and minimize operating
costs. It has the further benefit regularity permitting process by providing
assurance to the regulators ti^at will meet environmental quality
objectives..
of samples
gallons per da)
factor of 1(
requirec
snsure
laboratory bench-scale tests, involving the batch tests
liter pilot tests conducted at flow rates of a million
: data from a test system can only be scaled up by a
se orSpleral test systems of progressively larger size may be
ia full-scale design.
6$§y7
In certain extensive testing would be required beyond that typical of
laboratory or pilfjfscale testing. Those situations can include:
/k'My
S--7&W
wherejaffevative treatment technologies are proposed (e.g., biological treatment,
^treatment)
site conditions are extreme (e.g., extreme variations in wastewater flow due to
precipitation, cold temperatures)
where treatment goals are different than is normally practiced for the technology (e.g.,
effluent limits are very low).
7.1 Laboratory Testing
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Region 10 Mining Source Book
Appendix E - Wastewater Management
Treatability testing is necessary for all stages of a treatment train (e.g., the
chemical/biological treatment stage, the clarification and settling stage, filtration, and sludge
characteristics). Laboratory-scale testing is most useful for screening different treatment
processes. Laboratory testing is usually done on samples shipped directly to the laboratory.
Samples may be obtained from the mine site, in the case of mine drainage or site runoff, or from
mining process design studies conducted to evaluate milling or extraction processes. .
Laboratory testing can be done through bench-scale batch tests, or by continuous flow-through
tests. Selection of a test type depends on the goals of the test. Batch tests are less expensive and
quicker to conduct, but may provide less realistic results than flow-thrjMEh tests.
Bench-scale tests typically are conducted using
studies can be performed quickly and relatively inexpe
screen different treatment methods over a range of
(e.g., varying pH, reagent dosages, etc.). Use of diff
mine may cause discrepancies. For instance, because
is typically used to represent the effects of full-scale c
overestimate the efficiency of full-scale clarification.
Continuous flow-through tests typically
minute. Cyanide destruction chemistry can
Testing time may range from hours to daysfpcon
*£•$£-, •'
estimate reaction times that are more reitf sentat
/olumi
tely. SuchJi
J If
yater comositions'
7.2 Pilot-Scale Testing
Pilot-scale tests are use
identified in laboratory-s<
depending oof the objec
scale testsmigttfjbe concur
*^ *• -^r^.
in the test
trough membranefllrspaper filters
ich-scale tests may
•ed in milliliters per
dies of this type.
tests are useful to
brmance than batch tests.
promising treatment processes that are
may or may not be conducted on-site,
for conducting initial optimization pilot-
lace
the pilot-scale metallurgical testing
Pilot-scafetesfejequire lal^^^&mes of wastewater—flow rates may range from 5 gpm
to 100 gpm or loore. Studies are typically conducted for periods of a month to as long as a year
depending upon the treatefent,process being tested. The capital cost for test equipment is
significantly greater thai* tab-scale testing, although in some cases test units may be leased from
equipment suppliers. Conducting tests outdoors will allow for the influence of ambient
temperature variations to be evaluated, although it should be noted that above grade, steel units
may be more susceptiHe to freezing than permanent, in-ground tankage.
At the pilot-scale, clarifiers and filters will perform more like full-scale units. Wind
eifectsoa exposed pilot-scale clarifiers will be more representative of full-scale units, although
they may be magnified by the smaller scale. Reaction kinetics will approximate full-scale
performance. Considerations for designing a pilot plant testing program are shown in Table E-3.
[Table E-3. Pilot-Scale Treatment Design
E-20
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Region 10 Mining Source Book
Appendix E - Wastewater Management
1.
2.
Setting Up A Pilot Testing Program
Clearly identify the objectives of the study. If there are multiple
objectives, separate the program into phases of study.
Identify the parameters to be analyzed for the experiment. For
parameters such as metals that may be present in both soluble and
colloidal forms, always run both total and dissolved forms, jffi
Collect all samples needed for system evaluation. If the woricload
or analytical costs are excessive, do all tests, but less frecpeatty.
3.
*vS
Replicate feed conditions (i.e., temperature, pH, variations-itt
composition, etc.) as closely as possfete. Evaluate the test
under the range of flow loadings that^e expelled under full-scal|
operation.
4.
Understand the dependence of the prune s
r K-f*?
equipment performance. Failure to destroy c
performance of coagulation
ion exchange or reverse my im
performance due to clq
icillary
pair the
'ent of
5.
Operate the pilot f;
variability of
The
Depending upd
treatment
several alternatives for disposal of wastewaters
tory concerns, wastewater may require some level of
ractices.
Depending upoijlhe site water balance and regulatory constraints, a mine may propose to
;e wastewaterj|fa nearby water body. Discharge of wastewater to waters of the U.S. is
d under thiiiPDES program. The main text of the Source Book, Appendix B -
_.id Appendix D - Effluent Quality describe the NPDES program and
Jted to their proposed surface water discharges that mine proponents must collect
ixiii, ,,f)ES permitting requirements. In general the following information related to
surface water discharges should be provided to the regulatory agencies for NEPA analyses and
permitting decisions:
Characterization of effluent discharge flow and quality over range of proposed operating
conditions and closure (see Appendix D).
to
E-21
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Region 10 Mining Source Book
Appendix E- Wastewater Management
Description of water balance over range of operating conditions and closure (see
Appendix A).
Description of any wastewater treatment and ability of the treatment to achieve treatment
goals (effluent limits) over the range of effluent variability (see Section 7).
Description of outfall location and wastewater discharge system (e.g., pipeline, diffuser,
etc.)
Characterization of receiving water flow and quality, including seasonal variations (see
Appendix B). ^
Projected impacts on surface water resources (see Appendix Ba^ljAppendix G).
Monitoring plans for the receiving water and effluemfo,
^^ •* -:_ •£? •>,£' :::;
8.2 Land Application
><«l!
An alternative to wastewater treatment and direct]
application. Land application of mining wastewaters jj
regulation. However, States may have specific permitting requi
including protecting ground water resources. ThM^^tanate Stal
to determine data needs for land application ]
surface water is land
gbject to Federal
these activities,
ihould be contacted
In the mining industry, land
solutions. Such solutions are
properly accomplished, it can pos<
a mine operator proposes to use
information should be provi
d for spent cyanide leach
lion. If land application is not
and surface water resources. If
management method, the following
lermitting:
fewater proposed for land application
application (e.g., seasonal, climate, or soil moisture
E
Lampl
^Gjfimatie
i Area and
Chemical
id rates,
:ipitatSpf and evapotranspiration rates),
^pf the land application site,
soil characteristics, particularly infiltration rates,
• Proximity toSpffalDe water,
J||L • Depth to andjcharacteristics of underly ing ground water resources,
'•Jlf • Specific BMPs to avoid ponding and overland flow, and
f: • Projected impacts on ground water quality (and any potential indirect effects on
surface %ater).
• Wastewater and ground water monitoring plan that will demonstrate compliance with
regulations and enable early detection of any adverse impacts and corrective actions.
It is essential to have an accurate water balance for the site (see Appendix A, Hydrology),
including understanding precipitation versus evaporation versus infiltration rates. Mine
operators should project the potential effects on ground water quality and surface water
resources, taking into account any assumptions related to soil adsorption or other attenuation, for
the full range of operating conditions anticipated.
E-22
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Region 10 Mining Source Book
Appendix E - Wastewater Management
8.3 Evaporation/Infiltration
Infiltration and/or evaporation basins can be used to avoid or minimize direct surface
water discharges. Successful use of such basins depends on wastewater volume, facility design
and determining an accurate water balance. Any measures used to promote mfiltrajion (bottom
materials) or evaporation (spraying/misting) should be specifically described along%ith
predications as to evaporation and infiltration rates. Operators must demonstrate the ability
maintain sufficient freeboard in basins under all operating anil climatic conditions. Facilities
proposing to use these basins need to predict potential dirjfliiipacts on^mideriyuig ground water
and any possible indirect effects on surface water througllpfecharge. QpW
environmental monitoring plans should allow for early lection of effects
8.4 Underground Injection
Another alternative for wastewater disposal isjaj
injection can eliminate the need for direct discharge to%urface
poses potential risks to underlying ground the:
wastewater from mining operations is Control (UIC)
Program of the Safe Drinking Water Act. do not require
stion. Underground
/ever, this practice
si, injection of
rcompliance with drinking
:es. This may require water
individual permits. However, operatorsjipically
water standards for wells that could as djAlking wa
treatment prior to injection. In addpfon, statejllenerally regulations and permitting
requirements that address protgjfon. Minjpfperators proposing to use underground
injection should provide the foljiping infc
id volu^^R/astewater to be injected,
tion (aquifer delineation, composition of aquifer material,
inductivity, water quality, and uses),
of the aquifer,
^deptBPbnstruction materials, and QA/QC),
lumes and timing), and
ground water quality (and any potential indirect effects on
surface watei
WastewaterJiLd ground water monitoring plan that will demonstrate compliance with
regulationjpid enable early detection of any adverse impacts and corrective actions.
r
that the aquifer have sufficient capacity to receive the injected water (to
!s). In addition, operators must demonstrate proper construction methods and
ISrance. A particular concern associated with recently permitted underground injection
at the Pogo Mine in Alaska was potential effects on permafrost. Operators should also ensure
that injected waters are compatible with aquifer materials. For example, it would not generally
be appropriate to inject acidic waste into a limestone formation.
9.0 STORM WATER MANAGEMETN AND BEST MANAGEMENT PRACTICES
E-23
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Region 10 Mining Source Book
Appendix E - Wastewater Management
Storm water control and best management practices (BMPs) provide alternatives that can
reduce or eliminate the need for wastewater treatment and discharge. A primary goal of BMPs is
to prevent or minimize the generation and the potential for release of pollutants from industrial
facilities to waters of the U.S. This may be accomplished by minimizing the contact between
water and potential pollutant sources. For example, Section 6 of Appendix H, Erosion and
Sedimentation, describes some BMPs for erosion control. While these are primarily related to
sedimentation, many also apply to preventing contamination from other pollutantsJDther BMPs
should be utilized for spill prevention, proper management of chemicals%proper ^anagement of
solid wastes, etc. EPA has published several guidance manuals on
development of pollution prevention plans, and BMPs, inclwiing:
• Storm Water Management for Industrial Act,
Plans and Best Management Practices. 19
Storm Water Management for Construction Ac
Plans and Best Management Practices. 1992.
Guidance Manual for Developing Best Management Pra\
833-B-93-004.
Some states have also developed Blprguid
Department of State Lands published MgKdfor SH>t
Industry in Idaho, November 1992.
'eloping Pollutio\
R2-92-001
'ention
1993. EPA No.
7or example, the Idaho
Practices for the Mining
Mine operators should the of BMJpFto be used for wastewater and storm.
water management, their desigr^M how they will be maintained
throughout,the life their actual performance. As
discussediljeetion 2 NPDES permits for storm water
dischargeg'l^^l^ requil^^^^^nent and implementation of BMP plans and/or storm water
pollution pref^ii^Jans ). process water NPDES permits, may include specific
BMP requireniiefflS^i^fC requif^^^ffion of BMP plans.
10.0 WASTEWA
AGEMENT KEY ISSUES
•' This Appendix hf§ spfhrnarized alternatives for wastewater management and disposal,
including treatment and other options. Key issues emphasized related to wastewater
management include^
. • Every .attempt should be made to minimize wastewater generation and the need for
discharge. Mine proponents will need to demonstrate that proposed wastewater
^ inaiiagement practices will limit environmental impacts and meet all applicable
regulatory requirements.
• Estimated wastewater volumes must be based on an accurate site water balance (see
Appendix A, Hydrology). Wastewater volume and composition needs to be projected
under all operational and climatic conditions (see Appendix C, Characterization of
Ore, Waste Rock and Tailings and Appendix D, Effluent Quality).
E-24
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Region 10 Mining Source Book
Appendix E- Wastewater Management
All assumptions related to pollutant removal through treatment need to be supported
through proven performance at other mines and industrial facilities and treatability
studies. Operators must specifically demonstrate that any proposed wastewater
discharges will not cause exceedances of applicable surface water quality standards,
see Section 2.0 of the Source Book and Appendix B, Receiving Waters.
11.0 REFERENCES
American Water Works Association (AWWA), 1990. Water Quality a^ffrej^ment, Fourth
Edition, McGraw-Hill, New York. " *"
and Schwitzge
scale and Full-Scale
.vol. 77, no. 209,
1981.
Balistrieri, L.S., 1995. Impacts of Acid Drainage on Wejphds in the^n'SH|ptey, Colorado,
U.S. Geological Survey Mine Drainage Newslejjj-, No. 3, Jiaich, iflii
-Jir **'"
JlliilliMJ;&K*.. diiir
Bhattacharyya, D., Jumawan, A.B., Sun, G., Sund-Hagi
Precipitation of Heavy Metals with Sodium Sulfi]
Experimental Results, AIChE Symposium Seri^
American Institute of Chemical Engineers, New York.
Brodie, G.A., 1993. Staged, Aerobic Cor
History of Fabius Impoundment 1 apff'Uver
Program. In: Moshiri, G.A., ed.JJjk)nstrucji
Lewis Publishers, Boca Raton JJJL, pp. 1JIF165.
Treat1
Brodie, G.A., Britt, C.R., Tom;
Drains to Enhance Perfc
of th<
forWt
Brodie, G.A.,
in
-Draina
S. Bureau of
Drainage: Case
;see Valley Authority's
'ater Quality Improvement,
and TayJ|KH.N., 1993. Anoxic Limestone
ic Drainage Treatment Wetlands:
y. In: Moshiri, G.A., ed., Constructed
^lewis Publishers/CRC Press, Boca Raton, FL,
A., D.A., 1988. An Evaluation of Substrate Types
ds AclfPDrainage Treatment Systems. In: U.S. Bureau of Mines,
ce Mine Reclamation, Volume I: Mine Water and Mine Waste,
rmation Circular 9183, pp. 389-398.
ridge, M., 1995. Me of Passive Systems for the Treatment and Remediation of Mine
Outflows an4||lepages, Minerals Industry International, No. 1024, pp. 35-42.
i, T.R., and Updegraff, D.M., 1992. The Aerobic Removal of
^^ from Mine Drainage by an Algal Mixture Containing Cladophora. In:
Wceedings, 1992 American Society for Surface Mining and Reclamation Conference,
Duluth, MN, pp. 241-248.
Eger, P., Melchert, G., Antonson, D., and Wagner, J., 1993. The Use of Wetland Treatment to
Remove Trace Metals from Mine Drainage. In: Moshiri, G.A., ed., Constructed
Wetlands for Water Quality Improvement, Lewis Publishers, Boca Raton, FL, pp. 171-
178.
E-25
-------
Region 10 Mining Source Book
Appendix E- Wastewater Management
Erickson, B.M., Briggs, P.H., and Peacock, T.R., 1996. Metal Concentrations in Sedges in a
Wetland Receiving Acid Mine Drainage from St. Kevin Gulch, Leadville, Colorado. In:
Morganwalp, D.W. and Aronson, D.A., eds., U.S. Geological Survey Toxic Substances
Hydrology Program-Proceedings of the Technical Meeting, Colorado Springs, CO,
September 20-24, 1993, U.S. Geological Survey Water Resources Investigation Report
94-4015, p. 797-804.
Faulkner, B.B. and Skousen, J.G., 1996. Treatment of Acid^Mine D
Systems. In: Skousen, J.G. and Ziemkiewicz, P.Kpjli., Acid
and Treatment, 2nd edition, National Mine Reclamation Cem
267-274.
Garbutt, K., Kittle, D.L., and McGraw, J.B., 1994. Thi
Acid Mine Drainage: A Method of Selecting PI
Wetlands Receiving Mine Drainage. In: Inter*
Drainage Conference and Third International^
Drainage, U.S. Bureau of Mines Special
Gross, M.A., Formica, S.J., Gandy, L.C., a^
Materials for sulfate-Reducing wJStfands
Constructed Wetlands for
179-185.
Passive Treatment
: Control^
WV,
Gusek,J.J., 1995. Passive-Tji
LmeS^Mining Enf
of Wetland PlafMpecies to
use in Constructed
clamation and Mine
-------
Region 10 Mining Source Book
Appendix E - Wastewater Management
Drainage, Pittsburg, PA, U.S. Bureau of Mines Special Publication SP-06A-94, pp. 185-
194.
Hedin, R.S., Nairn, R.W., and Kleinmann, R.L.P., 1994. Passive Treatment of Coal Mine
Drainage, U.S. Bureau of Mines Information Circular IC-9389, 35 pp.
Hellier, W.W., Giovannitti, E.F., and Slack, P.T., 1994. Best Professional Judgement Analysis
for Constructed Wetlands as a Best Available Technology for the Treatment of Post-
Mining Ground-water Seeps. In: Proceedings of the InternatiorSand^eclamation and
Mine Drainage Conference and the Third Internatl
Acidic Drainage, Pittsburg, PA, U.S. Bureau o.
pp. 60-69.
Howard, E.A., Hestmark, M.C., and Margulies, T.D.,
forest products or on-site materials in the
In: Hammer, Donald A., ed., Constructed
Publishers, Chelsea, MI, pp. 774-779.
the Abatement of
SP-06A-94, «?.
Kim,B.M., 1981. Treatment of Metal Containi
Symposium Series: Water—1980, vol
Engineers, New York.
Knorre,
Griffiths,
Proces
in Tucs>
feasi
mine drainage irPSdlorado.
Treatment, Lewis
Kleinmann, R.L.P., 1991. Biological Seatmen
Proceedings of the Second'jfjternatio.
Drainage, MEND, Mon
^- An Overview. In:
on the Abatement of Acidic
ran With Hydrogen Peroxide Using the
and the Environment: Proceedings of a
p, December 11-14, 1984, Colorado State University, Ft.
^
voter Engineering: Treatment, Disposal, Reuse, McGraw-
ntal Mine Design and Implications for Closure, Land and Water,
September/Octer, 1996, pp. 32-34.
f Introduction to Wastewater Treatment Processes, Academic Press, Inc.
I Gusek, J.J., 1998. Mitigation of Water Contamination at the Historic Ferris-
jarty Mine, Wyoming, Society of Mining, Metallurgy, and Exploration Preprint 98-
1116pp.
Roeber, Jr., M.M., Carey, A.J., Cressman, J.E., Birdsey, R.S., Devarajan, T.S., Trela, J.A., and
Environmental Chemical Corporation, 1995. Water Treatment at Summitville. In:
Proceedings: Summitville Forum 1995, Colorado Geological Survey, Special Publication
38.
E-27
-------
Region 10 Mining Source Book
Appendix E - Wastewater Management
Scott, J.C., 1985. An Overview of Cyanide Treatment Methods for Gold Mill Effluents. In: Van
Zyl, D., ed., Cyanide and the Environment: Proceedings of a Conference in Tucson,
Arizona, December 11-14, 1984, Colorado State University, Ft. Collins, CO, pp. 307-330.
Scott, M.C. 1979. An EPA Demonstration Plant for Heavy Metals Removal by Sulfide
Precipitation, 2nd Conference on Advanced Pollution Control in the Metals Finishing
Industry, U.S. Environmental Protection Agency Report EPA-600-8-79-014.
Efflue:
rence in
Sengupta, M., 1993. Environmental Impacts of Mining: Monitoring, R&^prat&i, and Control,
^^ * ^Vitr^il-.f-J--^ .il'\. st^&f$b'
Lewis Publishers/CRC Press, Inc., Boca Raton, FL.^
Simovic, L., Snodgrass, W.J., Murphy, K.L., and Schm|jp.W.,
to Describe the Natural Degradation of Cyanid*
ed., Cyanide and the Environment: Proceedin,
December 11-14, 1984, Colorado State Univers:
Skousen, J., 1991. Anoxic Limestone Drains for Aci
vol. 21, no. 4, pp. 30-35.
Skousen, J., Sexstone, A., Garbutt, K., and
Treatment with Wetlands and Ano:
Wetlands Science and Technolo.
, CO, pp. 41-
'reatment, Green Lands,
Smith, A. and Mudder, T., 1991.
Journal Books Ltd.
Smith, K.Sy,Plumlee, G.S^aad-f icklin,
Mete&Mines
*
'94. Drainage
ent, D.M., ed., Applied
ton, FL, pp. 263-281.
ent ofCyanidation Wastes, Mining
9
Predicting Water Contamination from
"orkshop No. 2, International Land
Reclamation and Mimjjjtfj&hiQge Conference and Third International Conference on the
Abatement &f,Acidic Dr^^s^.S. Geological Survey Open-File Report 94-264, 112 pp.
Sung, W.
SO. Unities and Products of Ferrous Iron Oxygenation in
Aqueous Syst^jlj$E$xffionmental Science and Technology, vol. 14, no. 5, pp. 1-8.
' " * * } 4&^
U.S. Environmental Protection Agency, 1979. Draft Development Document for Effluent
Limitations Guidelines and Standards for the Nonferrous Metal Manufacturing, Point
^4r Source Categdjy, U.S. Environmental Protection Agency, Office of Water and Waste
Report 440/l-79/019a.
U.S. Environmental Protection Agency, 1994. Technical Report: Treatment of Cyanide Heap
Leaches and Tailings, EPA Report 530-R-94-037.
Viessman, W., Jr. and Hammer, M.J., 1993. Water Supply and Pollution Control, Fifth Edition,
Harper Collins College Publishers, New York, 860 pp.
Walton-Day, K., 1996. Iron and Zinc Budgets in Surface Water for a Natural Weland Affected
by Acidic Mine Drainage, St. Kevin Gulch, Lake County, Colorado. In: Morganwalp,
E-28
-------
Region 10 Mining Source Book
Appendix E - Wastewater Management
D.W. and Aronson, D.A., eds., U.S. Geological Survey Toxic Substances Hydrology
Program-Proceedings of the Technical Meeting, Colorado Springs, CO, September 20-
24, 1993, U.S. Geological Survey Water Resources Investigation Report 94-4015, p. 759-
764.
Whitlock, J., 1989. The Advantages of Biodegradation of Cyanides, SUE Journal, no. 84-37,
December 1989.
:\
Wildeman, T. and Updegraff, D., 1997. Passive Bioremediation of Meifeand^Mbrganic
Contaminants. In: Perspectives in Environmental Chemistry,/:i^|p0rd:|Jriiversity Press,
pp. 473-495.
Wildeman, T.R., Brodie, G.A., and Gusek, J.J., 1993. jjjjlland Design for Mining Operations,
BiTech Publishing Co., Vancouver, BC,
Wildeman, T., Cevaal, J., Whiting, K., Gusek, J, and Scfi|
Pilot-Scale Studies on the Treatment of Acid
Operation in California. In: International Lari9Reclamf
Conference and the Third International >
Drainage, U.S. Bureau of Mines Sp©
Ziemkiewicz, P.P., Skousen, J.G., and
Treating Acid Mine Drainag
pp. 31-38.
|3L1994a. Laboratory and
Closed Gold-Mining
rine Drainage
>t of Acidic
379-386.
f
icstone Channels for
Green Lands, vol. 24, no. 4,
E-29
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Region 10 Mining Source Book
Appendix F - Solid Waste Management
Table of Contents
1.0 GOALS AND PURPOSE OF THE APPENDIX F-l
2.0 TYPES OF SOLID WASTES AND MATERIALS F-l
2.1 Overburden F_l
2.2 Waste Rock , F-2
2.3 Tailings F-2
2.4 Spent Ore, Heap and Dump Leach Residues .,. J?T F-2
3.0 WASTE ROCK AND OVERBURDEN MANAG^&T . F-3
^< •' •''^'\J .&£ •'-•'.> n;Jl-..v^-O^ ^-', >.' .°\
3.1
3.2
3.3
3.4
Piles and Dumps ................. .jK ....... ........ |F-3
Mine Backfill .................... Jjf ..... v&?'. . . .
Use in Facility Construction ........ |^^.^|^ ......... ^ffj^Mi'^. . F-8
Use as Cover Materials ............ ............. ^tes^ ____ p-8
4.0 TAILINGS MANAGEMENT
F-9
7.0
4.1
Tailings Impoundments ?! A .• F-9
4.1.1
4.1.2
4.1.3
4.1.4
4.1.5
Site Characterization
Impoundment and
Liners
Tailings Water
Operational M
4.2
4.3
F-10
F-10
F-l 6
F-l 7
F-l 7
Dry Tailings Facilife^.... JT. JT F-18
Subaqueous M. F-19
4.3.1 WatetC
4.3.2 Di;
lineB
ipoundments F-20
brkings F-21
F-21
LEACH MANAGEMENT F-22
AND RECLAMATION F-24
id Revegetation F-25
«i Control F-26
itrol F-27
^ ontrol F-27
fnsiderations F-29
re Treatment and Neutralization F-29
"-Closure Monitoring F-30
^formation and Analytical Needs F-31
ACID MINE DRAINAGE F-31
7.1 Controlling the Acid Generation Process F-32
7.2 Moderating the Effects of Acid Generation F-33
7.3 Controlling the Migration of Acid Mine Drainage F-34
7.4 Collecting and Treating Acid Mine Drainage F-34
7.5 Information Needs F-34
F-i
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
8.0 REFERENCES F-35
List of Tables
Table F-l. Data Needs for Waste Rock Disposal Facilities ^. F-5
Table F-2. Operational Monitoring of Waste Rock Dumps and Heap Leach Fac|||ifs F-5
Table F-3. Example Siting Criteria for Tailings Impoundments and Dr^|feiiU|^Facilities. F-10
Table F-4. Operational Monitoring of Tailings Impoundments .. F-17
Table F-5. Data Needs for Heap Leach Facilities F-23
List of Figur
Figure F-l . Hydrologic Cycle for A Typical Waste Pile
Figure F-2a. Water-Retention Type Dam for Tailings^JjMrage
Figure F-2b. Sequential Raising, Upstream Embankment ----
Figure F-2c. Sequential Raising, Centerline
Figure F-2d. Sequential Raising, Downstrea
Figure F-3. Layered Waste System
F-ii
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Region 10 Mining Source Book
Appendix F — Solid Waste Management
address*
1.0 GOALS AND PURPOSE OF THE APPENDIX
Mining operations produce a variety of solid materials that require permanent
management. In order to prevent or minimize environmental impacts, applicants must pay
careful attention to the methods by which these materials will be disposed, the locations of the
disposal facilities, and the engineering designs of the disposal facilities. The largest mines may
generate over a billion tons of solid wastes that cover areas exceeding a thousand apres, and even
smaller operations must handle and dispose of formidable quantities of materialsimM can affect
"'-'v;V. J$£*"3 '&
large areas. The environmental behavior of these materials ranges fronife^igjpb deleterious,
with specific areas of concern arising from sediment loadin|gnetalsf^|tt|Ktetion, cyanide
release, and acidification. This appendix provides a briefjpplview oll^||^related to the
disposal of solid wastes which applicants may be expec
associated Clean Water Act permit application process
comprehensive review of solid waste disposal practic
Appendix C, Characterization of Ore, Waste Rock,
Sedimentation.
2.0 TYPES OF SOLID WASTES AND
This appendix is concerned with
materials that are generated and manag
Overburden
Waste rock
Tailings
dump 1
Other
constructiof
management ol
,minin
It is nojyteended
brmation i;
.and Appendix H,1Erosion and
of mining wastes and
sinerat
it may require disposal include smelter slag, trash,
itewater treatment sludge, and sewage sludge. The
irburden
wasllvfaifsr treatment is discussed in Appendix E.
v
Overburden conWipf unconsolidated to poorly consolidated materials such as soils,
lum, colluvium, o»acial tills that must be removed to access the ore body that will be
and processedjputchinson and Ellison, 1991). In most cases, overburden materials will
atain quantities of leachable metals or acid-generating minerals. However,
lilar to those described in Appendix C, Characterization of Ore, Waste
ngs, may need to be conducted to ensure the benign character of these materials.
Humt!Prl;h'forest soils may be slightly acidic and should be tested if they would be used as
cover materials or growth media atop metal-bearing wastes. Soils and unconsolidated deposits
may require proper handling and disposal to prevent erosion and sediment loading to streams and
other surface waters. Management of overburden is discussed in Section 3 below.
F-l
-------
Region 10 Mining Source Book
Appendix F — Solid Waste Management
2.2 Waste Rock
Waste rock is removed from above or within the ore during mining activities. Waste rock
includes granular, broken rock and soils ranging in size from fine sand to large boulders, with the
fines content dependent upon the nature of the geologic formation and methods employed during
mining. Waste rock consists of non-mineralized and low-grade mineralized rock. Materials may
be designated as waste because they contain the target minerals in concentration^ that are too low
to process, because they contain additional minerals that interfere with-processing and metals
recovery, or because they contain the target metal in a form that cannot*befjssocessed with the
existing technology. Materials that are disposed as waste at one point imm mine's life may
become ore at another stage, depending on commodity tPes, changes-in
technology, and other factors.
Waste rock may be acid generating and may co:
transported into the environment. These materials
testing (Appendix C, Characterization of Ore, Waste
will impact the environment over the short or long
handling and disposal procedures, or closure an
materials whose characteristics may pose si
in Section 3 of this Appendix.
2.3 Tailings
that can be moralized and
uire extensive geochemical
to determine if they
designs, waste
luired for those
anagement is discussed
Tailings are produced byJfpe'ficiati
metals from the remaining host |$ek.
ground to particle sizes raa®B^lom sam
ground ore using densi
techniques. ^The target meWf&ISiijteeparated from the mineral by leaching, electrowinning, or
separate the target minerals or
fns when primary ore is crushed and
. Target minerals are separated from the
•oth flotation, or other concentration
Jtailings) from these processes may make up to ninety
gh lower in the target minerals, the tailings can have a
other metalluracaJ techniques."
SmjJj^g^
percent of the onaggala^mined. <
wide depHfifs on the mineralogy of the primary ore material, the type
of separation process the efficiency of the separation process. Based on the
original constituents, th^railiag^nay contain acid-generating minerals and a variety of metals.
The small grain size of most tailings makes them an important potential sedimentation source
thai is susceptible to erpsion and downstream transport. Characterization of tailings are
discussed in Appendix C. Section 4 below discusses tailings management.
2.4 Spent Ore, Heap and Dump Leach Residues
Some primary ores, notably those of copper and gold, may be processed by heap or dump
leaching techniques. Dump leaching is the process of applying a leaching agent (usually water,
acid, or cyanide) to piles of ore directly on the ground, to extract the valuable metal(s) by
leaching over a period of months or years. Heap leaching is similar to dump leaching except the
ore is placed on lined pads or impoundments in engineered lifts or piles. Ores may be coarsely
crushed prior to leaching or may be leached as run-of-mine materials. Spent materials contain
F-2
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Region 10 Mining Source Book
Appendix F — Solid Waste Management
lower concentrations of the target mineral, and they may contain other metals, chemical
complexes of the target metal, acid-generating minerals, and small quantities of the leach
solution. After leaching, the spent ore may be treated by rinsing with fresh water or chemical
additives that dilute, neutralize, or chemically decompose leach solutions and metal complexes.
Characterization of spent ore is discussed in Appendix C. Section 5 below discusses the
management of spent ore.
3.0 WASTE ROCK AND OVERBURDEN MANAGEMENT
Waste rock and overburden materials are managi
regulatory requirements, and materials composition. M;
one site may be unsuitable at another due to factors as
material properties, climate, and cultural values. The
greatly depending on their mineralogical and chemical
factors. Some materials may be suitable for beneficial
structural rock, or decorative rock, whereas other mai
their permanent disposal in an engineered managemenffacility.
associated with waste rock materials or disposal
importance of comprehensive geochemical t<
engineering designs. This section briefly
techniques, highlighting the issues and iprmato:
other analyses
Piles and Dumps
Wa
>ck and o'v
lyst
compoi
they car?
may include
depending on
placed. In
these the bul
diffigprto evaluate qua|
Dump designs
ite conditions^
.suitableatf
'f* < *&'
f these mater
,
ipns and numerous-economic
;oad surfacing, aggregate,
xacteristics that require
ptaminant releases
phasize the
(eotechnical studies and
ivaste rock management
Id be addressed for NEPA and
. that c;
al to the
to beneficial use or that contain
Gnent, generally are placed in a location where
ill-,
7 the:
, area
jement is accomplished using a variety of techniques that
iping, and dozing. Dump design may vary markedly
ation and the terrain in which materials are being
ips may have faces of a few hundred meters height. For
water pressures with time is an important variable that is
f, but that may lead eventually to partial slope failure (Kent,
; may require some level of risk analysis to determine potential
Dts should failure Jffeur (Kent, 1997). Dumps placed as valley-fill deposits may require the
tion of rock jupHerdrains to permit the flow of water through the drainage. The materials
construct ijdsl drains needs to be thoroughly tested to ensure that they will not contribute
ler constituents to surface (EPA, 1993a; 1993b). Dump underdrains may need
!e mine drainage or storm water drainage systems that convey seepage to
facilities (see Appendix E, Waste-water Management).
Dumps that would contain waste rock capable of releasing significant quantities of
metals, acidity, or other constituents may require special design features or waste handling
practices to minimize the potential for environmental impacts (SRK, 1992a; Environment
Australia, 1997). Dumps can be designed with features to control or reduce acid generation,
F-3
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Region 10 Mining Source Book
Appendix F-Solid Waste Management
control the migration of poor-quality drainage, or collect and treat poor-quality drainage (SRK et
al., 1989). These features may include:
Waste segregation and encapsulation (i.e., cellular construction; SRK et al., 1989),
Blending and interlayering with materials that neutralize acidity and metals release (i.e.,
base amendments; e.g., SRK et al., 1989; Mehling et al., 1997).
Waste conditioning to remove acid generating minerals (SRK et al., 1989).4
Incorporating low permeability materials to slow the migration of poor-quality drainage
through a waste rock dump (SRK et al., 1989). 4' * v' ^
• Designing and preparing substrates that would minimize infiltration, and route seepage to
collection and treatment points.
Incorporating bactericides to slow the rate of pyrje^oxidation (SRK et aL, 1989;
. .. , nn~^ jSiift »~. if "K
Environment Australia, 1997).
Mines that produce a mix of acid-generating ani
careful to design and construct dumps in a manner that
**^
generation from which seepage could escape. Section
considerations in more detail.
Table F-l lists the type of data neede
some critical design factors of dump consbp$fion.
conducted during dump construction anjjpperatio:
NEPA analyses and permitting, it is crjteal thatjfflne app
information related to waste rock djfhp; managgnent:
Describe the criteria,
an4«eonomically
sudi^fpundati
and^herniejl
leachability.
tralizing waste rocfcmust be
tte local "hot spots" of acid
discusses acid drainage
ible site^BPa waste rock dump and
;s monitoring that may be
fgulatory agencies to perform
lupply the following
whether proposed sites are technically
'valuate the importance of critical factors
capacity, ground water conditions, and
.pare to any applicable regulatory requirements.
'bf waste rock to be disposed. Characterize the physical
ies of ilpwaste rock and how they relate to dump stability and
ition of waste rock is discussed in Appendix C.
•?•
Develop a water^aliiee (see Figure F-l) and predict the potential for seepage and run-off
from waste rock^dumps during dump construction, operations, and closure in order to
design appropriate wastewater management (e.g., containment and/or treatment, need for
; discharge permit, etc.). Various models are available to facilitate this. For example, the
HELP (Hydrologic Evaluation of Landfill Performance) model may be used to predict
leachate quantities. Where modeling is used, all model assumptions, input parameters,
and uncertainties should be disclosed and a sensitivity analysis may be necessary (see
Section 6 of Appendix A, Hydrology for general considerations related to modeling).
Methods for estimating a water balance for waste piles, modeling of waste rock dumps,
and techniques to estimate seepage quality are provided in Hutchinson and Ellison
(1991), MEND (1995), SRK (1992b), MEND (1996), and Price (1997). Water balances
are discussed in Appendix A. Wastewater management is discussed in Appendix E.
F-4
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
Describe how the dump will be constructed and managed during operations and closure in
terms of maintaining dump stability and reducing impacts to the environment. Develop
performance standards and compare to any applicable regulatory requirements (e.g.,
standards for containment, stability, etc.).
Develop and describe operational and environmental monitoring plans to ensure dump
stability, adherence to performance standards, and to identify impacts to surface and
ground water quality. Table F-2 identifies types of monitoring that may be required.
Monitoring plans should include action levels and contingency plans.. Monitoring plans
should incorporate quality assurance (QA) and qualjj|control (QC) (see Section 5 of
Appendix B, Receiving Waters for a description oj^llity assusanceand quality control
plans).
See Section 6 of this appendix for additional consid
and Section 7 for considerations related to acid drainag
Table F-l. Data Needs for Was
WasteJWek Characteristics
Methodologies
Topographical maps, Aerial photos
Geology and SoU|pncIuding j|lnit mapping
Geological maps, Engineering tests of site
samples.
Geological maps, Seismic zone maps,
Uniform Building Code (U.S. ACE, 1995),
Mine Plan of Operation, Engineering tests
of site samples.
See Appendix A
See Appendix A
See Appendix B
Mine Plan of Operation
See Appendix C
See Appendix C
Foundation Stability
Geotechnical and engineering tests of site
soil samples.
Geotechnical and engineering tests of waste
rock materials.
Surface Water Diversion
See Appendix H
Seepage/Run-off Collection and Treatment
See Appendix D.
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
Table F-2. Operational Monitoring of Waste Rock Dumps and Heap Leach Facilities
Type of Monitoring
Methods Used
Purpose
Geotechnical
Visual inspection; Extensiometer; Leveling
surveys; Soil strength testing; Soil borings.
Detect changes in slope stability,
compaction, and settling that may identify
structural weaknesses or signal potential
failure of the facility.
Surface Water
Flow/Runoff monitoring; Upstream and
downstream water quality analyses
Detect impacts to su:
iter quality.
Ground Water
Water table monitoring; Upgradient and
downgradient water quality analyses
.Detect i
water quality.
Hydraulic
Precipitation/Infiltration measurements!
Piezometers; Water quality analyses, i
Detect develop]
pile, itertify flui<
intefttal pore water
Thermal
Temperature Probes
:t temperature increasWWfhin the pile
iy indicate sulfide oxidation.
Pore Water
Water quality analyses
[uality of leachate, Early
idification
3.2 Mine Backfill
Mine backfilling is the act of trpisporting^Kd plac^^^^burden, waste rock, or tailings
materials in surface or undergroundjiffies. Tajpigs are often used as backfill than waste
rock or overburden. The techniq^^being^p& increajjpgly as a remediation measure (e.g., to
minimize the potential for acid ||ireration wajjllind/or the backfilled material) and to
minimize the. amount of sui^ceMisturbani^^fci^K^ store waste materials. Coarse-grained
' ''^" • X-'*'C^v;"'*:v^p^:JC1'L'V -• $&^f^$'~'^':^!JKiJiJ>iiJ$$iiii$1i? ^^
materials;syii|as wastej^^^^verburd^^^^lly are hauled to backfill locations using
vehicles%?oonvggrs. in rock volume that occurs through blasting and
excavation: miiielfeds can a^^ml^ate a maximum of approximately 70 percent of the
s'^S^ir^jSS*-- "*'I1S^^8SP!*"'»» .
original materla||i|ili^a§ excaviip|^R?m practice, the amount is likely to be significantly less.
The over^Hen still must be put to beneficial use or disposed of in
surface facilities. C^^^Bi^kfill materials will have comparatively high porosity and
permeability. Their larger surface areas (compared to solid rock) increase the availability of
metals and make these materials more susceptible to leaching and acidification. Materials that
would be stored in locations above the water table may be subject to periodic flushing by
infiltrating meteoric waters which could remove accumulated soluble oxidation products and
transport them to surface or ground waters.
Examples of the use of waste rock as mine backfill follow. The Goldbug Waste Rock
Repository at Landusky Mine in Montana is material that has been backfilled into the old
Goldbug Pit. The waste is placed atop 2-3 feet of crushed dolomite/ limestone which, in turn,
sits on a compacted clay liner that is engineered to drain to a collection area. Waste is segregated
within the dump to encapsulate acid-generating waste rock within non-acid generating waste.
Similarly, at the Castle Mountain Mine in California, waste rock has been used to backfill the
initial pit; there, no special handling was required or needed.
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Region 10 Mining Source Book
Appendix F — Solid Waste Management
If waste rock and overburden are to be used as backfill, mine applicants should provide
information of the following types to allow regulatory agencies to conduct full NEPA analyses
and make permitting decisions.
• Describe backfill operations and closure, including: timing and amounts of material
proposed for backfilling; means of transporting the material to the backfill site; types and
timing of storage, if any; if material is to be stabilized or otherwise treated, jull
^\&I>S&J4^
description of additives and treatment processes.
Describe physical characteristics (e.g., size dist
content) and chemical characteristics of backfil
Appendix C).
Predict the structural stability and leachability
rock.
on, includjiig
Description of monii
the jfced for chan
ferial and enclosing mine
Description of mine hydrology, incjjpmg
water quality in the mine, both and
potential for impacts to groundwater andjinrlace
&eeJpppendix A). Prediction of
in order to determine
to design appropriate controls.
verify predictions and allow detection of
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Region 10 Mining Source Book
Appendix F - Solid Waste Management
EVAPOTRANSPIRATION
ACTIVE ZONE
RUNOFF
SOURCE: Hutchinson and Ellison (1991)
LEACHATE
GROUNDWATER
Figure F-l. Hydrologic Cycle for A Typical Waste Pile.
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Region 10 Mining Source Book
Appendix F - Solid Waste Management
3.3 Use in Facility Construction
Waste rock and overburden materials can be beneficially used as construction materials at
many mine sites. Applicants proposing to use waste rock to construct roads, impoundments,
buttresses, underdrains, or other facilities or as rip-rap to line channels or stabilize embankments,
will need to conduct geochemical tests similar to those described in Appendix C,^
Characterization of Ore, Waste Rock, and Tailings. Testingprograms should be designed to
ensure that these materials will not themselves generate ajg|pKPotherwise cause negative
environmental impacts.
If waste rock and overburden are to be used in
should provide information of the following types to al
NEPA analyses and make permitting decisions.
'
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Region 10 Mining Source Book
Appendix F- Solid Waste Management
material from the mine to the storage and/or tailings areas.
Types and timing of storage, if any. This should include any storage site preparation
(e.g., run-on/run-off controls, temporary vegetation)
Geotechnical evaluation of the stability of the underlying tailings materials, with and
without the waste rock cover. ^,
jifF* .-sp5^
Geochemical evaluation of the waste rock/overburden that aUoiM0Ted|ition of changes
_ ^$$iiii$Gffiiiiffitvt$Q£&~'' ^^
in water quality of infiltrating run-on and precipitati^ja,, and
Description of alternate sources of cover materia|||*if any, ii
information provided for waste rock/overburde
Description of the ability of the cover material
closure solution
Demonstration that the cover will meet perfo:
^vegetation or othefrohg-term
regulatory
requirements during operations and following closure.
*
Description of monitoring pre
of the need for changes.
4.0 TAILINGS MANAGE
Tailings materials
practices mature becomii
* ^f-l O, <.5x -'*
under waKric^ers (sul
section briefJ3pi||
provided in% and
settings in
ions and allow detection
ipoundments. Other management
iposal in dry tailing facilities, disposal
pbsal in mine voids (mine backfill). This
^management techniques. More detailed descriptions are
?7); an overview of tailings disposal in impoundment
ssed in Section 2.3 and Appendix C, characterization
of the tailings^S&^rialsis,aril:ical tdlpPedicting environmental impacts and designing appropriate
management. As this section will discuss, extensive studies are necessary to evaluate potential
tailings management sites,%ndto "design and operate the sites.
4.1 Tailings Impoundments
\. Most minesdispose of tailings in engineered impoundments that cover areas ranging
ftom a few acres to more than a thousand acres. Thickened tailings solids typically are sluiced to
the impoundment and deposited by spigotting or through single-point discharges or cyclones. As
solid particles settle out of suspension, clarified water from the top of the impoundment is
generally recycled to the milling process circuit for reuse. In some cases (e.g., in areas of net
precipitation or following mine closure), water may be discharged from the impoundment, in
which case an NPDES or land application permit is required. Tailings impoundments may also
be used as emergency containment for excess storm water run-off from other areas of the mine
site and for disposal of sludges from on-site mine wastewater or sewage treatment plants.
F-10
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Region 10 Mining Source Book
Appendix F - Solid Waste Management
Critical issues related to the design and management of tailings impoundments are
discussed in the following subsections. Issues related to closure and reclamation of tailings
impoundments are discussed in Section 6.
4.1.1 Site Characterization.
The choice of a tailings impoundment site is based on the need to maximize desirabje features
and minimize undesirable features. Criteria typically used to determinejun appropriate tailings
impoundment site are presented in Table F-3. Site characterization studies need to include
comprehensive geological, geotechnical, and engineering evaluations to*ehsate the long-term
stability of the impoundment. As recently demonstrated at a Spanish zinc nwne, failure to
conduct adequate site foundation studies can lead to tailajgs spills, lea|:s,*and.|}a||ial dam
collapse (Mining Engineering, 1998). »*/ v«&i;;*-s^
Table F-3. Example Siting Criteria for T^aiogs Impoundments
and
Criteria to Detei
Anticipated tailings volume
Tailings grain size and composition
Hydrological conditions
Proximity to milling/processing
and magnitude of storms
-
eology aHRMraalization, including seismic activity
HydrogeQjIgical conditions, including foundation
pejjflability
Visu
Land
Ecologi
Site access
Run-on co:
Seepage release potential
Surface water discharge potential
Airborne release potential
Development and operating costs
Wetland impacts
/ and Embankments
, (1990)jpipothers discuss the different types of tailings impoundments and
re choice of impoundment type is determined primarily by site topography
5ross-valley impoundments are used where drainages are incised into hilly terrain.
SidelSTf impoundments are three-sided embankments arranged in stair-step fashion on broad
areas of sloping terrain. Valley bottom impoundments are constructed in stream valleys that are
wide enough to route streams between the embankment and opposite valley wall. Fully enclosed
ring dike impoundments are used on flat terrain.
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
Surface embankments can be classified into two general categories: water-retention type
dams and raised embankments (Vick, 1990). Water-retention type dams normally are placed in
valley bottoms, but occasionally are used on hillsides. They commonly are used for finely
ground materials such as flotation tails and to construct impoundments with high water storage
requirements. Water-retention type dams are constructed of earthen materials or concrete to their
full height prior to tailings placement. Because they are intended to prohibit horizontal fluid
flow, most are designed with impervious cores, filter material, drains, and rip-rap (Figure F-2a)
(Vick, 1990). ^
Raised embankments begin with starter dikes that are designed to contatethe amount of
tailings expected during the first few years of production. Starter dikes arexaoustructed using a
wide variety of materials that range from natural borrow-jsoils to waste rock S^^ttings (VicLj
^ * "CX% ™ *~ "^ ssF
1990). The embankment is raised periodically as dictated by mine operations, Booto^tosot
height is increased using upstream, downstream, or cenifiea&ie Construction methods liJRgftre F-
2b, -2c, and -2d) (Vick, 1990). Upstream construction is
requires the least amount of dike fill material; however.
requires careful control of tailings discharge (Vick, 19;
offers good seismic resistance and can be used for watSr
and requires the largest amount of fill material
advantages and disadvantages of the other mj
because embankment designs are compari
spreading construction costs over a Ion;
Stream diversions may be inc
embankment is constructed in thejpirttom o
runoff or in a valley that prcwludlfcsubstan
stream flowpr high precira^fcS diverti:
rater
the least costly because it
to liquefaction and
ownstream construction
gd is the most costly
iction shares
.ent method is popular
is the economic benefit of
of impoundment if the
ig significant drainage from storm
loff. Especially in areas of high
id impoundments can be necessary to
escent conditions in the impoundment for
useful for minimizing tailings erosion during storm events
'tion). Diversions can be constructed either as conduits
es that skirt the perimeter of the impoundment. The
particular site conditions.
(see
located below
feasibility of;|
•4^"'
Seepage control m^j^j^Sto protect the structures associated with a tailings facility and
to provide barriers to coataii|*fluids originating from the facility. It can be used to partly or
completely contain the lateral flow of tailings waters through the subsurface. Types of
' ^1$^*
commonly used seepage barriers, which restrict flow, include cutoff trenches, grout curtains, and
slurry walls (Vick, 1990). Seepage collection devices include collection wells, ditches, and
ponds. For so-called "zero discharge" impoundments where seepage is collected and returned to
the impoundment or otherwise used, long-term plans for seepage control/management have to be
considered during design, not just at the time of closure.
For the NEPA process, applicants should provide at least the following information related to
tailings impoundment and embankment design and operation:
• Describe the criteria that was used to determine whether proposed tailings impoundment sites
and designs are technically and economically feasible (see Table F-3). Evaluate the
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
importance of critical factors such as foundation stability, substrate bearing capacity, and
ground water and surface water hydrology. Compare predicted impoundment performance to
applicable regulatory requirements.
Specify the sources (and their acquisition), types and volumes of construction materials
required for the dam.
Investigate naturally occurring hazards at the dam site or within me|i|ip.ou|fiment area and
assess the risks that these hazards pose.
Perform stability and liquefaction analyses consisten^ith State ajp; olffili^ulatory
requirement.
• Describe impoundment £o:
perfornAce standard
Info
issues relatS
related to acid
l*sa
Provide the rate and volume of tailings to be disposl
chemical properties of the tailings and how they relaif
and leachability. Characterization of tailings is disjpSsel:
Develop a water balance and predict
normal conditions and under storm
collected and managed. See Secti
terize the physical and
ndment/embankment stability
ix C.
(including seepage) under
seepage, if any, will be
including construction QA/QC, and
regulatory requirements.
sundment liners and monitoring is discussed below. Closure
lents and discussed in Section 6 below. Issues
lection 7.
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Region 10 Mining Source Book
Appendix F- Solid Waste Management
Figure F-2a. Water-Retention Type Dam for Tailings Storage.
F-14
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
DECANT
POND -
SPIGOTTED
TAILINGS-
BEACH
TAILINGS
DISCHARGE
LINE
STARTER
DIKE
Figure F-2b. Sequential Raising, Upstream Embankment.
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
DECANT
POND-
SPIGOTTED
TAWNGS-
. BEACH
TAILINGS
DISCHARGE
LINE
STARTER
DO
Figure F-2c. Sequential Raising, Centerline Embankment.
F-16
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Region 10 Mining Source Book
Appendix F' — Solid Waste Management
Figure F-2d. Sequential Raising, Downstream Embankment.
F-17
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
4.1.3 Liners
At sites where mill effluents containing toxic constituents (e.g., cyanide or radioactive
isotopes) will be discharged to a tailings impoundment, tailings facilities may need to be fitted
with a liner system. The decision to choose a liner can be made after determining if the
substances contained in the tailings are toxic, if sufficient quantities of the substances exist, and
if sufficient quantities of those substance can reach ground water and degrade itffcladdition,
State regulations may require liners. Tailings pond liners can be compg||d o^^mpacted clay,
synthetic materials, or tailings slimes. Each has advantagesppd Compacted clay
liners provide good containment for relatively low materja|iid placen^%However, noty
all sites contain sufficient suitable material. Synthetic lifprs have
permeability and consistent quality, but disadvantages li|t includ^&h prod*te||
placement cost, and substantial foundation preparation
liners can be subject to damage by settling. Mill slime
permeability material that is used in a similar manner
can provide good containment. A slime liner also
foundation settling or geologic movement due to its pllsticity
include the necessity of careful material
toxic materials that could escape the containr
effectiveness of containment.
its. Bothcla.
inexpensive sourc^rolow
Careful placement of slimes
>r seal in case of
es of slime liners
material not contain
ie difficbftsrin predicting long-term
A "rSW * ***^ ^^
'&. w&>* V
F *»!? *TO
If a tailings impoundment is to be lined, jjpif a used over part of an
embankment, mine applicants shou|| pfovide^p>rmationwfthe following types to allow
regulatory agencies to conduct fyiffEPA ajj|J|rses andjpke permitting decisions.
Delineation of the
that might be lii
maximum amount
crucial for Intimating
Descri
lipated expansions, and the maximum area
approxllliPieliedule for expansions (including the likely
Jiner at any one time under various scenarios- this is
ff>.
>
|te preparation activities (compaction, etc.).
Description of tibife^^aSTd characteristics of liner proposed (type of synthetic material,
sources of clays,i?phyjical characteristics).
t-^~
Information on compatibility of tailings and liner materials, including long-term
compatibility.
Description of leak detection, if any, and contingency plans for detected leakage.
Analysis of liner effectiveness, such as a demonstration of how liner will meet applicable
performance standards for containment over the long term.
4.L4 Tailings Water
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
Tailings waters may contain elevated concentrations of metals, process chemicals, acidity,
and other constituents that have the potential to impact surface and ground water quality.
Applicants must provide water balance information that describes the flow and composition of
waters into and out of the tailings impoundment. Modeling may be required. Water balances are
discussed in more detail in Appendix A (Hydrology) and Appendix E (Wastewater
Management). Applicants who request an NPDES permitted discharge from the tailings
impoundment should provide information on flow and composition and treatment of such
discharge. NPDES permitting needs are discussed in the main text of the sourcejfeook and in
Appendix D (Effluent Characterization)
4.1.5 Operational Monitoring.
Monitoring of active tailings impoundments shcfiid focus oa-d^
embankment stability, surface and ground water qualir^fcdgrjfi^id water ow see
1 i-^^^^^^I^K^^^^^^^ -<•'•" C-"''-""*'•'•'v>'':-v
Sengupta, 1993). Embankment stability can be geotechn'^Pmethods
and visual observation. Surface and ground water by routinely
collecting and analyzing samples from upstream and Downstream surface
*¥'$$£'' "^I^^^^^^^^^M^^S
water stations should be located such that they would receive from retention
.ponds, seepage collection sumps, and at confluences.
Ground water stations should be located of an u^^ndment in order to
detect changes to ground water flow that mound that would
form beneath the impoundment (Vick, stations should be
sampled on a regular basis and analyjiggrrbr a sujpTof conlpiSnfs as specified in an approved
Sampling and Analysis Plan (see
Characterization of Ore, Waste
ijable F
rof cons
zceivingjjaters, and Appendix C,
tional
Ig of Tailings Impoundments
Metho
Purpose
,al inspec
testing; Soil
; Pore water
Detect changes in slope stability, compaction, and
settling that may identify structural weaknesses or
signal potential failure of the embankment.
^ Upstream and downstream
lyses.
Detect impacts to surface water quality.
Wate«bKnonitoring; Upgradient and
dowaiiradient water quality analyses
Detect impacts to ground water quality; determine
influence of recharge mound on ground water flow.
,al (opacity), PM-10 monitoring
Detect blowing dust, detect high paniculate
(particularly important if high arsenic in tailings)
Flow monitoring, Water quality analysis
Early detection of water quantity and quality
changes, potential for acid drainage, detection of
process chemicals
Applicants should submit information of the following types to allow full NEPA analyses
and informed permitting decisions.
Description of all monitoring plans, both for operational components as well as
potentially affected environments, including frequency, the components to be monitored,
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Region 10 Mining Source Book
Appendix F'— Solid Waste Management
4.2
the parameters to be monitored, and quality assurance/quality control. Table F-4
identifies the types of monitoring.
Description of strategy and schedule for updating and refining monitoring plans,
Description of how monitoring data will be used during the active life of the facility,
J^\.-
Description of contingency plan for responding to various monitoring results, including
identification of action levels for each monitored component andijlararneter (i.e., the level
that will trigger further monitoring or some type of plher acti0n
"
action).
Dry Tailings Facilities
g corrective
Dry tailings disposal is a relatively new method«
dewatered to less than saturation using thickeners, belt fif
Although best suited to dry climates and is most produjisve
tailings facilities also have been approved in wet climates (e.g.^
Kensington Project in Alaska). Dewatered tailin^^ftfcansporte
haul trucks, conveyors, or special pumps.
covered. Dry tailings facilities typically
less disturbed area at any given time (Jq
In addition, "paste" tailings^wtrich an
(see Section 4.4), may be disposedonthe
paste materials have an initial moisture co:
which is held by surface tensiesnin the
permit the,jjal to be«meiJ)ut insi
tailings that havfrtreen
[ter presses (Johnson, 1997).
shortages exist, dry
dk Mine and the
feposal facility via
compacted, and
placement, resulting in
lely to backfill underground mines
ig to Norman and Raforth (1998),
imately 20 weight percent, most of
This amount of water is sufficient to
create free-draining water or particle
segregatioa&^|||v percenioJFgO|ri4and cement or fly ash can be added to increase material
strength ancfo
A sigffliaeant advantage to detailings management is that the technique reduces the
potential for surface andipgaB^water contamination since it eliminates free process water from
the piler"Other advantagesllc|l(fe the ability to reclaim more process water, the ability to place
dry material at locations where wet placement is difficult or impossible. Dry tailings
management also may .ifsult in less water to treat and discharge, which can be a significant
advantage in light of tibe zero discharge provisions of the NPDES New Source Performance
Standards. A disadvantage to this type of management is that the unsaturated and moist
condition of the tailings would permit any iron sulfide minerals that are present to oxidize and,
potentially, form acidic leachate. Other disadvantages include high unit costs and difficulty in
placing materials in wet climates. Saturation of a dry tailings pile by precipitation potentially can
lead to slope failures if a facility is not properly designed to accommodate storm events.
As with tailings impoundments, the choice of a dry tailings disposal site is important.
General siting criteria are shown in Table F-3. Facilities are most easily located along valley
bottoms, on flat plains, or on gently sloping surfaces. Placing dry tailings on hillsides with steep
slopes requires larger facility footprints and higher pile heights, and it presents challenges for
F-20
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Region 10 Mining Source Book
Appendix F — Solid Waste Management
access and foundation stability.
The decision to use dry tailings management depends partly on the volume of water
required by the process system and the site water balance. For some zero discharge facilities, the
use of dry tailings disposal may return too much water continuously to the process system. For
example, the water storage and/or evaporative loss components of a tailings impoundment may
be important elements of the facility water balance.
If applicants plan to use dry tailings management techniques, th|||shm|*i[provide
information of the following types to support NEPA analys§l|and
Describe the criteria that was used to determine sBS'ther propepif
are technically and economically feasible (see F-3)^fvaluate
critical factors such as foundation stability, sub|gg^bjejsj|8ig capacity,
and surface water hydrology. Compare impouri
regulatory requirements.
brmance to applicable
Perform stability and liquefaction analyses consistent
requirements.
Characterize the physical and che
impoundment stability and leacl
Describe the rate and to
dewatering the tailings,
De;
o
d topography, site preparation and
long-term configuration, and means of
e ofjpings to
stewaJtmanageifiSnt.
facility
erms,
facility.
normal
collected an
ad other regulatory
and how they relate to
ed and managed, means of
lict effluent quantity and quality (including seepage)
|and under storm scenarios. Describe how seepage, if any, will
'f. See Appendix E.
w
Describe facilitjponstruction and management, including construction QA/QC, and
performance jjmdards necessary to meet applicable regulatory requirements.
[describe operational and environmental monitoring plans, including
Incy plans and action levels. Monitoring similar to that described in Table F-4.
Closure issues are discussed in Section 6, below. Issues related to acid drainage are
discussed in Section 7-
4.3 Subaqueous Tailings Disposal
The objective of subaqueous tailings disposal is to maintain a water cover over the
F-21
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Region 10 Mining Source Book
Appendix F-Solid Waste Management
tailings to control oxidation of sulfides, bacterial action, and subsequent acid generation (see
Appendix C for discussion on the geochemistry of acid generation). This objective can be
accomplished by depositing mine tailings directly into a body of water such as a constructed
impoundment, a flooded mine, a freshwater lake, or a marine environment such as a fjord or deep
marine channel. Although practiced in other countries, disposal of tailings into lakes and marine
environments is not allowed in the United States. For most industry sectors, NPDES effluent
limitation guidelines prohibit process water discharges to waters of the U.S., including both fresh
and marine waters. Effluent limitation guidelines also limit the discharge of tota|iu*spended
solids. For these reasons, disposal of tailings into lakes or marine envjf|i|mefl!iis not discussed
in this Appendix. Instead, the Appendix focuses on the useJCwaterj " '"*'
impoundments and disposal into flooded mine workings.
Subaqueous tailings disposal controls acid gem
oxidation process, thereby controlling acid generation;
problems caused by wind and water action on tailings
creating a reducing environment, suitable for supporting
organisms in sediments, in which soluble metals are p;
generated by the reduction of nitrates. The physical arfcl chemf
materials are controlled by the oxidation,
interactions with the overlying water col
turbulent motion.
4.3.1 Water Covers over Construct
,;,*!•'<§.""
v Hf
Disposal of tailings into
maintained is a relatively new
facilities would require
and contim^tetructural
" ' *a.
require a permanent and
conditions at fhe1x)ttom.
ting av£
surface erosl
depositional basf
nitrate reducing micro-
and ammonia is
of the tailings
fft sediments;
d to wave induced
where a permanent water cover is
.ber of practical difficulties. These
ice to ensure a permanent water cover
Tand dikes. In addition, these facilities would
supply and a minimum water depth to maintain anaerobic
The advantages o£rising unoaPwater disposal in a constructed impoundment include the
ability to mitigate the*p^ctecti0n and release of acid drainage and lower implementation costs
compared to the costs ofa?solLc6ver. Disadvantages include heightened potential for
embankment failure dueto seismic events or erosion due to additional liquid in the impoundment
compared to conventional tailings impoundments; the displacement of resources (e.g., habitat,
vegetation, etc.) at thetocation of the tailings impoundment; the potential inability to keep
tailings flooded a$d maintain anaerobic conditions; and the potential release of metals present in
pore water solutions or in soluble mineral phases. Many of these disadvantages may be more
difficult to overcome in impoundments that are not designed for permanent water retention (i.e.,
whose design is modified after initial construction).
Subaqueous tailings disposal in constructed impoundments has been evaluated at two
mines in Canada. At the Highland Copper Mine, British Columbia., a tailings impoundment was
flooded and monitored to evaluate the efficiency of the subaqueous disposal technique (Scott
and Lo, 1992). At the Fault Lake Mine, Falconbridge, Ontario, test plots of saturated tailings
were developed and evaluated to determine the effectiveness of various test scenarios.
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Region 10 Mining Source Book
Appendix F - Solid Waste Management
Design and operational issues that should be analyzed forNEPA disclosure and
permitting relating to water covers include:
• The issues discussed in Section 4.1 for the siting, design, operations, and monitoring of
tailings impoundments also apply to constructed underwater disposal impoundments
(e.g., characterization of tailings, stability evaluation, water balance, monitoring plans,
etc.). Additional issues specific to water covers include: A
iN x*4-?
• Designs must demonstrate that the tailings will be maintained spin anaerobic state to
prevent sulfide oxidation and that the tailings will bg^aced b^&il^level of wave
action to prevent redistribution.,
• Impacts to the aquatic environment must be evailated,
:
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Region 10 Mining Source Book
Appendix F - Solid Waste Management
Describe the disposal operations and closure, including: timing and amounts of tailings
proposed for disposal; means of transporting the tailings to the backfill site; if material is
to be stabilized or otherwise treated, description of additives and treatment process.
Characterization of the backfill tailings and any additives.
Demonstrating the structural integrity and physical consistency of the backfill material.
Characterizing geochemical effects of tailings solids and fluid;
water or pit lakes, including results from any necessaf| mode.
Hpiality of ground
Characterizing any predicted discharges to groujg|?water or sj
Conducting rigorous hydrogeological and limm
will remain continuously flooded.
Developing a monitoring plan for operational a
predictions and allow detection of the need for^hanges
4.4 Mine Backfill
riods to verify
ive actions.
Tailings materials can be used
used to provide a working floor, Pjjj/vj? wall
recovery, minimize surface subsiplftce, and,J
Because most backfill appli
dewatering) and low com]
operations and slimes stilt
delivered undefgftmnd usi:
using positive-displacement pi
dewater undergronnd^ad jequi:
that is environmeitaffiPlileiJitable.
require
ty, gene
;kfilMpftdergrora»irines. In this setting, they are
roof support and stability, maximize ore
i control (Vick, 1990; Johnson, 1997).
f high permeability (to permit
le sand fraction of tailings are used in these
sposal method (Vick, 1990). Tailings are
systems or, if the tailings have been dewatered to "paste,"
son, 1997). Slurried tailings (60 to 75 percent solids)
control to ensure that fluids are handled in a manner
backfills (80 percent solids) offer lower permeability
ound water flow (Johnson, 1997). Although paste backfills
water extracted during the filtering operation requires
and can be used to restrict i
*Sv .*jjw»
introduce less water
environmentally accepta^leMsposal (Johnson, 1997). In some cases, tailings may be augmented
with cement or fly ash tb provide additional stability and/or alkalinity.
Issues associated with the disposal of tailings as backfill that should be analyzed for
NEPA disclosure include:
• Describe the backfill operations and closure, including: timing and amounts of material
proposed for backfilling; means of transporting the material to the backfill site; if material
is to be stabilized or otherwise treated, description of additives and treatment process.
• Characterization of the backfill tailings (e.g., particle size, chemical and physical
characteristics), including the effects of additives such as cement or fly ash.
F-24
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Region 10 Mining Source Book
Appendix F — Solid Waste Management
• Predict the structural stability of backfill material and enclosing mine rock.
• Determine/predict the potential reactivity (particularly acid generation potential) of backfill
material (tailings and any additives) and enclosing mine rock. This would involve laboratory
testing, modeling, and other methods, as described in Appendix C.
Prediction of water quality in the mine and whether a discharge is needed in order to determine
potential impacts to ground water and surface water and to design appropriate controls.
• Description of monitoring program to be used to verify predictions and allow detection of the
need for changes.
Issues associated with acid generation is discussedj||rther in §|efion 7 <
in Appendix C.
a natural
are
5.0 SPENT ORE/HEAP AND DUMP LEACH
Although the purpose of heap leach
cross into the realm of waste management
presently use three types of heap leach fac^
(also termed "on-off' pads) are desigm
and transported to a separate dispo;
on the pad for a new leach cycle.
facilities designed for a single
fresh ore is placed on newly^
constructec
eml
choice d?
mineralogy"
vats or tanks ra5
manner s:
tailings igftTSection
:tals, these facilities
Ltchinsor^p'Ellison, 1991). Mines
on, 1991). Reusable pads
>ent ore materials removed
cycle; fresh ore is replaced
tpanding pads are engineered
ig in place at the end of the leach cycle;
Valley leach facilities are
pined on the downstream side by an
lly similar to dedicated pads. In part, the
^site topography, geotechnical considerations, and the
tics of the ore materials. In some cases, ore is leached in
such cases, the spent ore is generally disposed in a
; or in a manner similar to that used for conventional
Process solutionMia^Wie ability to degrade surface and ground waters should they
from leach padsfid solution storage and conveyance systems. For most facilities,
ion contammen^TO.chieved through the use of impermeable liners beneath leach pads,
and pregn^Mid barren solution ponds, and dual-wall piping. Hutchinson and Ellison
rtypes of natural and synthetic liners that are commonly used for these
rdless of the type of system that would be used, leach pads, solution storage
ponasralfa*solution conveyance systems will need to designed to accommodate the added
volume of water that occurs during low probability storm events. This makes performing a
rigorous analysis of the predicted water balance crucial to project design. Wastewater
management issues are discussed in more detail in Appendix E.
Many of the criteria for choosing the locations of waste rock dumps and tailings
impoundments also apply to the locations of heap leach facilities. Primary among these are
F-25
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Region 10 Mining Source Book
Appendix F - Solid Waste Management
economic factors such as haulage distance and geotechnical concerns such as foundation stability
and liner integrity. The types of technical data that may be required for locating a suitable site
are summarized in Table F-5.
Table F-5. Data Needs for Heap Leach Facilities
Critical Design Factor
Data Needs
Data Source/Methodologies
Facility Site Selection
Topography
Topographical maps,
'
photos
Geology and Soils, including fault mapping
Geologi
'sampl
Seismicity (natural and blasting-induo
Geologi-
Unifo|rfluildii?
)fOpei
fe samples.
Ground Water Hydrogeology
Process Solution System
Facility Water Bi
Pile/Dump Construction
Foundation
Geotechnical and engineering tests of site
soil samples.
Geotechnical and engineering tests of ore
materials.
See Appendix H
Collection and/or Liner
Model results, Meteorological data; See
Sections 4.1.4,4.1.5,6.5
L a reusable pad, or spent ore removed from vats or tanks,
will require disposal m^s^j^ facility. The manner of disposal will be governed by the
likelihood that these ma^^i^^uld impact surface or ground water quality by releasing metals,
acidity, process chemicals, orother constituents. Consequently, the potential for water quality
impacts is expected to be a function primarily of the mineralogy of the spent materials and the
completeness of rinsing and process chemical neutralization actions (see Section 6.6). Spent
materials that are.unlikely to have deleterious effects could be disposed of with other waste rock
materials; those expected to contribute to poor water quality may require special handling or
disposal (e.g., encapsulation).
Issues associated with heap management that should be analyzed for NEPA disclosure
and permitting include:
• Describe the criteria used to determine whether proposed heap sites and designs are
technically and economically feasible and how they fulfill regulatory requirements. Many
of the criteria will be similar to that discussed for siting waste rock dumps and tailings
-------
Region 10 Mining Source Book
Appendix F — Solid Waste Management
impoundments. Table F-5 lists some of the critical criteria.
Characterize the physical and chemical properties of the heap material and how they
relate to heap stability and leachability (see Appendix C).
Prepare a water balance and predict the potential for seepage and run-off from the heap in
order to design appropriate wastewater management. Various models are available to
facilitate this. Where modeling is used, all model assumptions, input parameters, and
uncertainties should be disclosed and a sensitivity analysis
Wastewater management is discussed in Appendix
in
6.0
Closure1
preventing
and cherfSly stabl
erosKprrunoff, seepag<
stability of ft
S'
Describe how the heap will be constructed and
terms of maintaining heap stability and reduci
performance standards and compare to any appl
predict liner performance). Additional closure cojj
of this appendix.
Develop and describe operational and
stability and predict impacts to surfs
types of monitoring that may be
and contingency plans.
For disposal units for spenj
information on unit desi
and abandonment.
iop
jdatory requiremellPte.g.,
are discussed in Section 6
to ensure heap
Table F-2 identifies
tould include action levels
from vats and tanks, provide similar
ng performance following closure
>SURE AND RECLAMATION
ient waste disposal facilities should be directed toward
Primary considerations center on creating physically
at will not impact surface and ground water resources through
jlown dust (Hutchinson and Ellison, 1991). Over the long-
luch as waste rock dumps and spent leach piles depends on factors
as the build-up ofjllre water pressure within the pile, erosion during high intensity
itation events,jjipe angle, and the presence of internal weaknesses (e.g., inclined layering)
the pile. IjMjPIition to those produced by sluicing practices, internal weaknesses may be
piles by sulfide oxidation, which creates hardpan layers that restrict
iltration (Blowes et al., 1991).
This section briefly describes aspects of closure and reclamation and associated analyses
that should be performed for permitting and NEPA analyses. The reader is referred to Section
7.0 for more detailed descriptions of techniques to control the formation and migration of acidic
drainage. Appendix H, Erosion and Sedimentation provides a more complete discussion of
runoff and sediment transport control.
F-27
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Region 10 Mining Source Book
Appendix F-Solid Waste Management
6.1 SoUs Placement and Revegetation
An understanding of soil resources can help applicants to establish realistic goals for
revegetation success and increase the likelihood of achieving those goals. Most mining activities
directly impact soils. The actions of stripping and replacing topsoil and overburden disrupt the
horizons that produce a soil's physical and chemical characteristics and often inverts them in the
process of creating stockpiles. These actions also lead to soil compaction. However, even where
soils are not stripped, the operation of heavy equipment causes compaction mat ejpf Significantly
reduce soil productivity (Ellis and Mellor, 1995). Compaction reduce^^e SpjSe within a soil
which decreases the infiltration of water and air. Soil porosife is criti^fiili^intaining the types
•?*''.•'•* t£s&- *^-£<. ;*'.^£$$&&f- &y*<*'£.'v.£'•<•?••. ^"^ ** ^
of biological activity that produce a healthy soil.
If there is a single key to reclamation success, ig
biological activity within the soils or the growth mater
holding capacity, nutrients/pH, and stability are all crit
i the ne
The biological activities occurring within soils are key c
Micro- and macroorganisms within the soil conduct
such as the decomposition of organic material and nutrient eye
Biological activity typically is lost when soils for
technique that maintains biological topsol
to an area undergoing reclamation (SengutfflfTii^S),
can enhance revegetation efforts by maiapaining
hauling is only practical where concui^fit reclarfftion is
hauling is not possible, islands of s^fivl plantjjpterial
, 4fls»-''
reclaimed areas to serve as propane sourcejlpr impoj
propagules can be collected jusiJISnow
maint
soil.
amation success.'
.o plant-soil interactions.
soil-building processes,
>d Mellor, 1995).
ime. One handling
an area to be stripped
Iso termed 'live hauling',
>f indigenous species. Live
ihployed; in settings where live
>il can be transplanted into newly
it soil organisms. Windblown
idRedente, 1991).
tions a^^BHable to operators, including directly seeding
il or growth media prior to seeding. Where soil resources
glyzed for their suitability as plant growth media. Based
incorporated to improve fertility or texture (e.g.,
y _ can be either chemical fertilizers or organic
mulche|such as paper^^^^s, straw, hay, manure or compost which are tilled into the
upper portion of the soi^^p^sbils, particularly in the western U.S., have limited phosphorus
conMits and require ferftzatron. However, the addition of a nitrogen-rich fertilizer requires
thorough consideration because the addition of nitrogen to native soils has been shown to
infltence the species Composition at reclamation sites and may predispose a site to invasion by
weedy .species adapted to such a nutrient-rich regime. In some cases, successful nitrogen
additions have been made after plants have had two to three years to become established
(Peterson et al.; 1991). Seed mixtures should be developed based on the type of soil being placed
on the site. While the long-term reclamation goals may reflect a later successional stage,
reclamation plans should acknowledge the limitations that 'new' soils may impose on the
establishment of new vegetation.
Reclaiming a large facility (e.g., a tailings impoundment) typically requires that a site
have significant soil resources so that a suitable growth medium can be placed. For mines that
are situated in arid or mountainous terrains with limited soil resources, this may be problematic.
F-28
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Region 10 Mining Source Book
Appendix F — Solid Waste Management
In these areas and in others where soils may need supplements, operators have used biosolids
(i.e., sanitary sewage sludge), wood chips, and other means of increasing organic matter in soil.
Recent studies have shown that cattle grazing can provide an innovative, effective, and cost-
competitive option for reclaiming fine-grained materials (i.e., tailings). In Miami, Arizona,
penned cattle helped to establish growth media on abandoned tailings by trampling hay mulch,
urine, and manure into the upper tailings layer (Norman and Raforth, 1998). In addition, cattle
helped to minimize erosion by creating sidehill terraces and pathways and to establish seed
germination areas in hoof depressions.
6.2 Runoff and Erosion Control
The long-term control of sediment erosion and
protecting water quality and aquatic resources. Runo
through grading, surface diversion, revegetation, and
Management Practices (BMPs) established by the op
and erosion is discussed in detail in Appendix H,
Grading and recontouring waste rock dumps
typically is intended to provide stable slopes tha;
position is an
d erosiomcontrol
rdance wif
and controllfifrunoff
recontouring techniques can be used to create
formation on sloping surfaces and to
conveyance structures. In general, tai
be). More often, long-term diversio:
across tailings facilities to control
In most cases, runof
embankmca&Lor flow
direct
and the em!
structures. R
were initi
conveyjppetain flo
evenj|j|PThis may req
mcjlise the size of divi
'•K,i>y-l
guid'
cap leach piles
Grading and
it reduce gully and rill
neered swales or other
embankment faces may
constructed around or even
Pa dispo;
aver im
:corl
|gs embankments
ic and intendec
tether from dumps, piles, tailings
routed to a sediment control structure as
\jand SelSfflfflRon. Surface water diversions are used to
gpss a facility in order to prevent erosion of waste materials
JStorm event planning is key in designing diversion
mding conveyance structures and detention basins, that
leet design life guidelines, may require reconstruction to
| from low probability precipitation events (e.g., 100 or 500 year
is to stabilize the beds and banks of ditches (e.g., with rip-rap),
ictures and sediment detention ponds, or raise the height of
•revent storm water overflow. Closure requirements will likely be site-
promote long-term drainage control.
Y
in Section 6.1, revegetation typically requires the addition of soil
irthe placement of topsoil or other growth media to provide a suitable substrate for
planffpfwli. Establishing vegetation on waste facilities lessens infiltration and decreases the
potential for erosion by diminishing rainwater impact and providing soil cohesion. Surface
armoring is intended to cover fine-grained, easily eroded materials such as tailings with more
resistant, coarse-grained rock.
6.3 Infiltration Control
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Region 10 Mining Source Book
Appendix F - Solid Waste Management
Infiltration control is used to minimize the amount of meteoric water that enters a waste
disposal facility. These measures can help to stabilize facilities by maintaining low pore water
pressures and decreasing the potential for water quality impacts by reducing seepage quantities
and limiting oxygen diffusion. Requirements for infiltration control depend on climatic
conditions and the characteristics of the materials contained in a given disposal facility.
Facilities situated in arid climates or that contain non-reactive materials may not require
infiltration controls at closure.
ps, seals, and
es. Caps and
,an acceptably Igw
Infiltration control typically is achieved through the use of impej
capillary barriers, by establishing vegetation, and by recontojring fa
seals may be composed of clay or other natural materials ||ipare com
permeability or a variety of synthetic materials such as IfffC, HDPE,
mixes. Compacted natural soils are effective at contro^g water Jafrltration
suffer long-term degradation. Similarly, clay caps
synthetic membrane covers may offer superior they can suf ong-term
degradation through the loss of plasticity, cracking, or settling
(Sengupta, 1993). Surface sealants such as shotcrete robust alternatives
to membrane covers. Capillary barriers can have a variety and Ellison,
1991). In general, they consist of a vegetated drainage layer that
is, in turn, underlain by a low permeability (Figure F-3)
(Hutchinson and Ellison, 1991). They are.
layer and divert it from the surface of tbjfwaste
moisture that falls onto the surface of allisposal,
•filtK^-'
(see Section 6.1). Infiltration alsojpipe dec:
ponding and promote runoff (seejffefion 6.
6.4 Seepage Control
ition penetrating the soil
Delation will take up
that which will infiltrate
ng facility surfaces to eliminate
for certain facilities upon closure. Requirements for
eantly for waste management facilities in arid and
991). In general, seepage can result from infiltrating
through a facility, the flow of surface or ground waters
:es
fetieJease of pore waters upon dewatering and consolidation of
•&j%* ".CfV^ AX C7
seepage corii
humid climates
precipitation^ 6j£
through^ facility, or
... ""*
tailings.
Seepage controjjirom waste disposal facilities can be achieved through the use of
impermeable liners aad?systems that are engineered to collect seepage and route it to treatment
facilities. Typically, these systems are designed to work in concert with runoff and infiltration
control systems. Types of seepage collection systems include sumps, ditches, drains, and ground
water interception wells (Hutchinson and Ellison, 1991). Seepage conveyance systems at closure
may need to be designed to accommodate increased seepage and runoff that could result from
low probability storm events. Poor quality seepage may need to be routed to a treatment facility
prior to its discharge to surface waters. These facilities can be in the form of active or passive
treatment systems (see Appendix E, Wastewater Treatment).
F-30
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Region 10 Mining Source Book
Appendix F — Solid Waste Management
PRECfflTAnON
EVAPORATION
INFILTRATION r-,
RUNOFF
i and Ellison (1991)
Figure F-3. Layered Waste System.
F-31
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Region 10 Mining Source Book
Appendix F- Solid Waste Management
6.5 Other Considerations
The potential deleterious effects of highly reactive wastes (for example, materials with a
net acid generating potential) can be lessened by installing covers materials that limit oxygen
diffusion into waste facilities (e.g., Sengupta, 1993). Water covers are effective oxygen barriers,
but require maintenance to assure they remain intact. In addition, the use of water Covers require
tailingsjftad othe
* ver tailings
that the original impoundment structure be designed to maintain such covers. Synthetic
membranes such as PVC and HDPE provide effective oxygen control bppfiajgluifer puncture or
long-term degradation. While compacted soil covers offer J^ited oxj^pi||&itrol, saturated soils
may preclude significant oxygen diffusion (Sengupta, 19J
The control of windblown dust may be an issue
materials. Dust can be suppressed by maintaining a
natural or synthetic covers, or promoting vegetative grc
tailings should be thoroughly investigated to ensure that]
strength to support the waste rock load (see Section 3.J
In some cases, facilities may be recontoi
visual impact. While coal mining regulatior
approximate original topography, there is
permits may require that any facilities
topography and support the approved mst mimr
use of waste rocklas a cover for
materials possess sufficient
•pography and reduce
pits be regraded to
-coalmines. However,
insistent with the surrounding
6.6 Spent Ore Treatment
Spent ore materials
materials.tPore waters ai
8 ,&
leach facilities or in taili
if «B °*
prevent chemical josfeases to
neutralization
this can be
sssed heap and leach facilities or tailings
that remain in closed acid and cyanide heap
u'de leaching can be mobilized by infiltrating rainwater. To
lent, leached materials may require rinsing and
ierious compounds prior to facility closure. In general,
• Applying a neutral r^^Solmtion to remove constituents from the processed material, then
collecting and treating me solution; piles are rinsed until effluent concentrations reach pre-
determined acceptable levels.
• Applying a rinse^solution containing chemical or biological agents that neutralize or
chemically decompose constituents of concern in situ.
Insituheap rinsing requires that piles have sufficient permeability to permit neutralizing
fluids to penetrate through and contact all materials within them. Piles with insufficient
permeability or with highly variable permeability or fluid flow pathways may need to be
dismantled and treated in smaller batches (EPA, 1994b). Climate can play a significant role in
determining the length of time required for complete neutralization. For example, cold weather
may slow or halt biological breakdown of cyanide. Experience has shown that initial treatment
may produce effluent that meets constituent guidelines, but that effluent quality may degrade
after treatment stops (EPA, 1994b). Thus, some facilities may require repeated treatment until
F-32
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Region 10 Mining Source Book
Appendix F — Solid Waste Management
effluent quality remains at acceptable levels.
Li et al. (1996) describe lab and pilot-scale experiments designed to determine the
appropriate methods to rinse and neutralize an acid leach pile. Their results demonstrated that
decommissioning tests should use large diameter columns or field-scale test piles to determine
rinsing times, solution application rates, and decommissioning costs. These experiments also
showed that precipitation and dissolution of secondary minerals controls the metals^ontent of
the rinse effluent. Rinsing duration depends on the volume of the leache(d material! in the pile,
their mineralogical and chemical characteristics, and physical factors sju^bas plSmeability,
porosity, and precipitation. Accelerated artificial rinsing, in which nei|^ttzi^ solutions (e.g.,
calcium hydroxide) are applied using the leach solution system, can e^Ji^tei1110^ acidity,il
and soluble metals from a large heap leach pile in a reasonable perioc
,111111
There are a variety of techniques that can be u
breakdown residual cyanide and metal-cyanide compl
(EPA, 1994b summarizes these techniques; see also Appj
of these methods produce by-product ammonia or nitrj
effluent waters. In general, chemical or biological agents can
leach solution system. Rinsing continues until ttj
reaches an acceptable level. Processed tailinj
are treated prior to discharge to a tailings jsB*6und:
It should be noted that rinsh
other metals (notably, selenium,
not meet regulatory standards foj
leachate from infiltration. I^als
section (ruB&? and erosii
impo!
fol, infil
tally or biologi
leach and tailingWacilities
•tewater Treatment). Some
ire additional treatment in
leach piles using the
;e from the pile
'on leaching typically
.ucing cyanide, can mobilize
ienic) toJJlb point that rinsate or leachate will
lout trejginent of the rinsate as well as future
[ other closure issues discussed in this
;epage control, soils placement and
Srtant considerations following neutralization of
spent he
Post-<
litorinl
Pclosure
and uJHentify any pro
andjpthods of closure
Itions, evaluatio
ations of avi
lance of
is conducted to ensure long-term protection of the environment
!e early stages of their development. Depending on the facilities
ed, post-closure monitoring may include visual inspections of site
embankment integrity, surface and ground water quality monitoring,
le capacity in sediment retention structures, assessments of the
diversions, seepage collection, and seepage treatment systems, and the
of reclamation activities. For each type of monitoring conducted, there
ction levels that trigger specific responses (which could include such things as
, notification of authorities, correction action). These responses should be
clearly laid out in contingency plans that describe the actions that have to take place when an
action level is reached or exceeded. The types of monitoring that are required, the schedule by
which they are conducted, and the parties that are responsible for conducting monitoring
activities will depend on site-specific conditions and requirements.
6.8 Information and Analytical Needs
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
iction ojfuh-off
Issues associated with closure and reclamation that should be analyzed for NEPA
disclosure and permitting include:
• Describe closure and reclamation techniques and timing. Develop performance standards
for reclamation measures. The performance standards should be consistent with
regulatory requirements and also provide for long-term stability (chemical and physical).
Describe any performance bonds or other financial assurance th&Jmayibe provided to
authorities as potential mitigation for impacts, the means of c
provided, and the conditions and timing of release||
Develop a long-term water balance, including
low probability conditions.
Predict the short- and long-term effectiveness
revegetation, and other stability and water coni
used to evaluate cover effectiveness and revege
predict long-term impacts of weathering..
Describe any treatment and neui
abandonment, including verific
Describe all monitoring
afterward, including QA/|
the types of monitorin:
7.0
Acid ni'MeidMife represent the greatest environmental concern at
mining solilpvastes discussed in this appendix may be potential sources
of AMDf mitigate AMD production from solid mining wastes are
briefly discussed in thisf^M^^anagement and treatment of AMD wastewaters is discussed in
Appendix E. The chemfetrylof AMD production is described briefly here and is described in
detail in many of the references provided in this section.
&
AMD occurs when sulfide-bearing mine wastes and materials react with meteoric water
and atmospheric oxygen to produce sulfuric acid. The most reactive sulfide phases are the iron
sulfide minerals pyrite, marcasite, and pyrrhotite. Nordstrom et al. (1979) summarize the pyrite
oxidation process. In the initial stages of acid formation, pyrite reacts with water and oxygen to
form ferrous iron and sulfuric acid. Ferrous iron is slowly oxidized to ferric iron by oxygen. As
pH decreases below 4.5, ferric iron also begins to oxidize pyrite and it becomes the primary
oxidant at pH values below 3.0. Iron oxidizing bacteria (e.g., T. ferrooxidans) greatly accelerate
the oxidation of ferrous iron to ferric iron and serve to catalyze pyrite oxidation at low pH.
When this occurs, the presence of oxygen has little effect on the rate at which pyrite oxidizes to
form acid. Acid generation at low pH is controlled by bacterially mediated ferric iron oxidation
ontrols, seepage controls,
field test plots may be
y be required to
c, ore, or tailings prior to site
.ges of reclamation and closure and
itingency plans. Section 6.7 describes
F-34
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Region 10 Mining Source Book
Appendix F—Solid Waste Management
(Singer and Stumm, 1970; Nordstrom et al., 1979).
AMD can be initiated from any pyrite-bearing mine material that is exposed to air and
water. This includes ore piles, overburden and waste rock dumps, tailings impoundments, pit
walls, underground workings, and spent ore heaps. Appendix C describes tests that can be
performed on tailings, waste rock, etc. to determine their acid generating potential. To the
greatest extent possible, new facilities should seek to prevent acid drainage rather than treat or
abate AMD after it forms. ^
7.1 Controlling the Acid Generation Process
Acid generation can be controlled by regulating
components (pyrite, oxygen, water) or the catalyst (bac
removing pyrite from materials and wastes or precludir
and oxygen, water, or bacteria. The process can be slowl
the environmental conditions that sustain bacterial po|
Pyrite can be removed from mining wast
common procedure produces a sulfide-rich:
be handled separately (SRK et al., 1989). JfKbughJ
part of the beneficiation scheme, it is neijplr a praeffear
pyritic overburden or waste materialj, Jlbeconoilfc under
contain pyrite.
At any stage of the
acid produAn. Removi:
diminisl
covers
covers that
more permeafr
is achieved
in excl
excli
B
barriers
^Syntheti
jtected
e pf
can be;
ions between the'sSKd materials
bactericides or eliminating
The most
ng.
ition, which then can
Utilized at mines where it is
ctive solution for treating
workings, or pit walls that
(or moisture) and air are required for
'ctants from the site of acid generation will
xttiment Australia, 1997). Low permeability
jcomplish this task. Capillary soil barriers are engineered
ibility layer (generally clay) that is interlayered with
which serve as evaporation barriers. Erosion control
with gravel. Capillary soil barriers have proven effective
iJation from mine wastes and materials (greater than 90 percent
control agent (Groupe de Recherche, 1991; Robertson and
Id., 1994; Yanful et al., 1994; Ziemkiewicz and Skousen, 1996a).
effective control agents, but are less widely used because of their high
typically are PVC or HOPE liners placed over acid-generating materials
over of soil or rock (SRK et al., 1989; Ziemkiewicz and Skousen, 1996a).
>?fpir
"can be excluded from mine materials and wastes by submerging them under
wateffSRK et al., 1989). Although water contains a small amount of dissolved oxygen, it is
present in amounts insufficient to oxidize pyrite. Mine materials can be submerged by depositing
them in a constructed water body, depositing them in a flooded mine pit or underground working,
or depositing them on a specially prepared surface where they are naturally saturated by perched
water (Broughton and Robertson, 1992). Subaqueous tailings disposal, which has been used
successfully at several mine sites (Dave, 1993; Dave and Vivyurka, 1994; Fraser and Robertson,
1994;; Environment Australia, 1997), is discussed in greater detail in Section 4.3.
F-35
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Region 10 Mining Source Book
Appendix F- Solid Waste Management
At advanced stages of the acid-generation process, bacterial oxidation of ferrous iron
catalyzes acid generation. Consequently, controlling bacterial populations can provide
immediate control of acid generation. Anionic surfactants (e.g., sodium lauryl sulfate;
Kleinmann et al, 1981), which typically have liquid formulations, can be sprayed onto
potentially acid-generating materials prior to or during disposal (Parisi et al., 1994). Because
these compounds eventually decompose or leach from treated materials, they must be reapplied
periodically and are not a permanent solution to the AMD problem (Ziemkiewicz and Skousen,
1996a). However, slow-release formulations (sorbates and benzoates; I^cksonjjpu., 1985) are
available and have proven useful (Splittorf and Rastogi, 1995). Bact
when applied to fresh, unoxidized pyritic materials and canjpi, a use:
combination with other control methods (Ziemkiewicz aglpiousen,
7.2 Moderating the Effects of Acid Generation
The effects of acid generation can be moderatec
before it can migrate from a disposal site. Neutralization]
conditions, but commonly it is spurred by chemical ar
?s aip'most effective
ien used in
and materials prior to or during disposal or added to the cover
disposal. When amendments are added to the
pile near the site of acid generation. In
alkalinity to meteoric water that i
materials include both acid-generating
construction practices can be used to rapgate a<
workings can be reduced or prever& bac
dizing any acid thlRIf generated
a result of natural
$1 directly to the wastes
it are placed following
ials, occurs within the
added^^Kver materials supply
•net neu
"gene
lizes acidity. Where mine
;cial handling and
migration from underground
Several types of <
Ziemkiewiejland Skousei
carbonatefcl^ch lacksiil
, -, •<••>'">- -«•
and easy*te|
gypsum (hyl
Kiln dust frorri^
reactive, abs
content^ bat also ma;
Phosp>
ing andjpding mine portals.
at mine sites (SRK et al., 1989;
1997). Limestone (calcium
msive, readily available, safe, effective,
bustion ash is a mix of coal ash, lime (calcium oxide), and
icts quickly and hardens into a cement upon wetting.
mix of unreacted limestone, lime, and ash that is highly
enting abilities. Steel slags also have high calcium oxide
concentrations of trace metals which make them less suitable for
il1
; which will react with ferrous iron to form insoluble coatings on
widespread use.
pyrite, is more expensi\|fli8if the other amendments listed above.
ftp^r*"
The amount of^alkaline material that must be added to wastes and materials prior to their
disposal can be estjpated from acid-base accounting tests of the disposed materials (see
Appendix G)aaiibf the amendment. A cost-effective control strategy can be determined during
pre-mining planning when different disposal options can be tested. In theory, amendments
should be thoroughly admixed with mining materials prior to disposal to maximize their
chemical effectiveness. In practice, however, this may require repeated handling of the materials
which may not be cost effective. Consequently, it is common for amendments to be interlayered
with mine materials (termed layered base amendments). As described below, the construction of
piles that include heterogeneously distributed, layered base amendments is critical to their .
success.
F-36
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Region 10 Mining Source Book
Appendix F — Solid Waste Management
The construction of waste and material piles plays a significant role in determining
whether mixed acid-forming and acid-neutralizing materials will generate acid mine drainage.
The formation, storage, and flushing of acid products in a rock or tailings pile depends on flow
paths within the pile, flushing rates through different parts of the pile, the distribution of acid-
generating and acid-neutralizing materials, and localized physical and chemical conditions
(Robertson and Barton-Bridges, 1992). Consequently, it is possible for rock piles with net
neutralizing character to develop areas of acid generation. Regardless of the amount of
neutralizing material contained within a rock pile, acid generated within the pile wilf not be
neutralized if it percolates along a flow path that does not encounter alkaline materials
(Ziemkiewicz and Skousen, 1996b). Although hydrologic ^deling
-------
Region 10 Mining Source Book
Appendix F— Solid Waste Management
potential for and neutralization of AMD (see Appendix C). Testing proposed throughout
the mine's life should be described.
Describe and predict the effectiveness of AMD prevention, moderation, or control
measures. Present results of geochemical testing and treatability testing as well as
modeling results.
%
Describe QA/QC procedures during operations to ensure that acid-generating material is
handled according to mine plan.
Describe monitoring programs to confirm that
working and/or to provide early warning of any
action levels and contingency plans.
A
measures ate
.entof J'
F-38
-------
Region 10 Mining Source Book
Appendix F - Solid Waste Management
8.0 REFERENCES
Bell, A.V., Riley, M.D., and Yanful, E.G., 1994. Evaluation of a Composite Soil Cover to
Control Acid Waste Rock Pile Drainage. In: Proceedings of the International Land
Reclamation and Mine Drainage Conference, U.S. Bureau of Mines Publication SP-06B-
94, p. 113-121.
Blowes, D.W., Reardon, E.J., Jambor, J.L., and Cherry, J.A., 1991. The|i^rnjiiibn and Potential
Importance of Cemented Layers in Inactive Sulfide Mine
Cosmochimica etActa, vol. 55, pp. 965-978.
Broughton, L.M. and Robertson, A.M., 1992. Acid RoMDrainag^Brbm Miie|i|^I]iere we are
Now. In: Science Applications International A^^eneration
from Non-Coal Mining Wastes: Notes of a 7
Environmental Monitoring Systems Laboratory,
U.S. Environmental Protection Agency, Las Vj
Dave,N.K., 1993. Panel Wetlands-A
Tailings under Water, MEND
Dave, N.K. and Vivyurka, A.J., 199
Laboratory and Field S
and Mine Drainage
306.
Ellis.
Cast
\ Draft report prepared for the
search and Development,
•gedPyritic Uranium
ada.
&*
derating Uranium Tailings —
International Land Reclamation
ines Publication SP-06A-94, p. 297-
ent, Routledge, New York, NY.
^Sulphidic Mine Wastes and Acid Drainage, Best
lent in Mining, Commonwealth of Australia, May 1997,
., and Onysko, S.J., 1985. Control of Acid Mine Drainage by
fidal Materials, U.S. Bureau of Mines Information Circular, IC-
srtson, J.D., 1994. Subaqueous Disposal of Reactive Mine Waste: An
. Update of Case Studies — MEND/Canada. In: Proceedings of the
Wonal Land Reclamation and Mine Drainage Conference, U.S. Bureau of Mines
^Publication SP-06A-94, p. 250-259.
Groupe De Recherche En Geologic de L'Ingenieur, 1991. Acid Mine Drainage Generation from
a Waste Rock Dump and Evaluation of Dry Covers Using Natural Materials: La Mine
Doyon Case Study, Quebec, Final report submitted to Service de la Technologie Miniere,
Center de Recherches Minerales, 22 pp.
F-39
-------
Region 10 Mining Source Book
Appendix F- Solid Waste Management
Hutchinson, I.P.G. and Ellison, R.D., 1991. Mine Waste Management, California Mining
Association, Sacramento.
Johnson, J.M., 1997. Tailings Disposal Design. In: Marcus, J.J., ed., Mining Environmental
Handbook, Effects of Mining on the Environment and American Environmental Controls
on Mining, Imperial College Press, London, pp. 428- 444.
A.
Kent, A., 1997. Waste Rock Disposal Design. In: Marcus, J.J., ed., Mining Env0mmental
Handbook, Effects of Mining on the Environment and Americarfi^ijvir^mental Controls
on Mining, Imperial College Press, London, pp. 444*447.
Kim, A.G., Heisey, B.S., Kleinmann, R.L.P., and Deul
and Abatement Research, U.S. Bureau of Minei
Kleinmann, R.L.P., Crerar, D.A., and Pacelli, R.R.,
Drainage and a Method to Control Acid Fo:
305.
id Mm
"\;
in Circular, I
Levens, R.L., and Boldt, C.M.K., 1993. En
Department of the Interior, Bureai
Li, M.G., Jacob, C., and Comeau, G.?
by Rinsing. In: Tailings a^Mine
X
"S
Mehling,PJ&;.Day, S
Delay; Hitigate or
Fourth'iffiemationa!
June 6,
pp.
istry of Acid Mine
ineering, vol. 33, p. 300-
Waste Sandfill, U.S.
Sulphuric Acid-Leached Heap
Rotterdam, pp. 295-304.
ith, Blending and Layering Waste Rock to
lid Generation: A Case Study Review, Proceedings of the
on Acid Rock Drainage, Vancouver, B.C., May 31 -
MENDr 1995. Hydrow^y^Waste Rock Dumps, Mine Environment Neutral Drainage Program
Associate ProjecfrP^T-l^atural Resources Canada, Ottawa, ON, July 1995.
MEND, 1996. Guide for Predicting Water Chemistry from Waste Rock Piles, Mine Environment
Neutral Drainage Program Report 1.27.la, Natural Resources Canada, Ottawa, ON, July
* 1996.
sir
Mining Engineering, 1998. Bedrock Shift Caused Spill in Spain, Industry Newswatch Column,
Mining Engineering, vol. 50, no. 11, p. 23.
Munshower, F.F., 1997. Seeding and Planting. In: Marcus, J.J., ed., Mining Environmental
Handbook, Effects of Mining on the Environment and American Environmental Controls
on Mining, Imperial College Press, London, pp. 205-217.
F-40
-------
Region 10 Mining Source Book
Appendix F — Solid Waste Management
Nordstrom, D.K., Jenne, E.A., and Ball, J.W., 1979. Redox Equilibria of Iron in Acid Mine
Waters. In: Jenne, E. A., ed., Chemical Modeling in Aqueous Systems: Speciation,
Sorption, Solubility, and Kinetics, American Chemical Society Symposium Series vol
93, p. 51-79.
Norman, D.K. and Raforth, R.L., 1998. innovations and Trends in Reclamation of Metal-Mine
Tailings in Washington, Washington Geology, vol. 26, no. 2/3, pp. 29-42. *.
Parisi, D., Horneman, J., and Rastogi, V., 1994. Use of Bactericides to Control!Acid Mine
Drainage from Surface Operations. In: Proceedings^ the International Land
Reclamation and Mine Drainage Conference, of Mines Publication SP-06B-
94, p. 319-325.
Peterson, G.A., Williams, S.E., and Moser, L.E., 1991.
on Semiarid and Arid Region Soils. In: Skuji
Resource and Reclamation, Marcel Dekker, Ini
artilizer Use and Its Effects
id Lands and Deserts, Soil
'vv
Price, W.A., 1997. DRAFT GuidefeJandR^mmendeMfethods for the Prediction of Metal
Leaching and Acid Rock Columbia, British Columbia
Ministry of Employmeifpd Inveg|hkEjgggf? and Minerals Division, Smithers, B.C.,
Apaiy997, 143
Reeves, F.B.
Skuiii
fe Importance of Mutualism in Succession. In:
' and Deserts, Soil Resource and Reclamation, Marcel
cer, Inc.,
Rol
fson, A.M. and BffiftfBridges, J., 1992. Cost Effective Methods of Long Term Acid
Mine DrainageJpmtrol from Waste Rock Piles. In: Science Applications International
CorpOTation,^^dicting Acid Generation from Non-Coal Mining Wastes: Notes of a 1992
report prepared for the Environmental Monitoring Systems Laboratory,
rch and Development, U.S. Environmental Protection Agency, Las Vegas,
Schroeder, P.R., Dozier, T.S., Zappi, P.A., McEnroe, B.M., Sjostrom, J.W., and Peyton, R.L.,
1994. The Hydrologic Evaluation of Landfill Performance (HELP) Model: Engineering
Documentation for Version 3, Office of Research and Development Report EPA/600/R-
94/168b, U.S. Environmental Protection Agency, Washington, D.C., September 1994.
Scott, M.D., and Lo, R.C., 1992. Optimal Tailings Management at Highland Valley Copper,
F-41
-------
Region 10 Mining Source Book
Appendix F- Solid Waste Management
CIMBulletin, July/August 1992, pp. 85-88.
Sengupta, M., 1993. Environmental Impacts of Mining: Monitoring, Restoration, and Control,
Lewis Publishers, Boca Raton, FL.
Singer, P.C. and Stumm, W., 1970. Acid Mine Drainage: The Rate Determining Step, Science,
vol. 167, p. 1121-1123.
Skousen, J.G. and Ziemkiewiscz, P.F., eds., 1996. Acid Mine
Treatment, 2nd edition, National Mine Land Reclamation
^<^ii^Sf'^! '•'-' "'
PP.
Splittorf, D. and Rastogi, V., 1995. Ten Year Results
Mine Land, Proceedings of the American Society^
Annual Meeting, Gillette, WY, p. 471 -478.
Steffen, Robertson and Kirsten (B.C.), Inc.,
Process Engineering, (SRK et al.),
British Columbia Acid Mine
Vancouver, B.C.
Nor
icide-Treated arlrKeclaimed
Mining and Reclamation
i,l9:
, and Gormely
'.ockDrijage Technical Guide,
'ech Publishers, Ltd.,
Steffen Robertson and Kirsten (SRg,l992a.Jpne Rockjjuidelines: Design and Control of
Drainage Quality, Saska^pKan Enj^nmentjp Public Safety, Mines Pollution
Control Branch Report
KP
Adelines for Acid Mine Drainage Prediction in
ffen Affairs Canada, Ottawa, ON.
%>H£ '•"•
U.S. Environmental
Report, Landusl
;ency (EPA), 1993a. EPA Region VIII - NPDES Inspection
ay 11,1993.
U.Si Environmental Protection Agency (EPA), 1993b. EPA Region VIII - NPDES Inspection
Report, Zortman Mine, May 12, 1993.
.
U.S. Eivkonmental Protection Agency (EPA), 1994a. Technical Report: Design and Evaluation
of Tailings Dams, Office of Solid Waste, Report EPA 530-R-94-038, August 1994, 59
pp.
U.S. Environmental Protection Agency (EPA), 1994b. Technical Report: Treatment of Cyanide
Heap Leaches and Tailings, Office of Solid Waste, Report EPA 530-R-94-037,
September 1994,62pp.
F-42
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Region 10 Mining Source Book
Appendix F— Solid Waste Management
Vick, S.G., 1990. Planning, Design, and Analysis of Tailings Dams, BiTech Publishers,
Vancouver, B.C., 369 pp.
Woodward-Clyde International-Americas, 1998. Stibnite Area Site Characterization Report,
Report prepared for the Stibnite Area Site Characterization Voluntary Consent Order
Respondents, August 3, 1998.
Yanful, E.G., Abbe, B.A., Woyshner, M., and St-Arnaud, L.C., 1994. Field and,liboratory
Performance of Engineered Covers on the Waite Amulet Tailin^^/w; proceedings of the
International Land Reclamation and Mine Drainagejfonferej^^&^BurQsa. of Mines
Publication SP-06B-94, p. 138-147.
Ziemkiewiscz, P. and Skousen, J, 1996a. Overview Minejpfainage:
Strategies. In: J.G. Skousen and P.P. Ziemkie\^^|ds^czWMme Drim
and Treatment, 2nd edition, National Mine Center, Morf iltown, WV,
p. 69-78.
*'*'*
Ziemkiewiscz, P. and Skousen, J, 1996b. Prevention of Acid
Addition. In: J.G. Skousen and P.F. ZieniHliiliz, eds.,.
and Treatment, 2nd edition, National
p. 79-90.
;e by Alkaline
Drainage: Control
ation (Spiter, Morgantown, WV,
F-43
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Region 10 Mining Source Book
Appendix G—Aquatic Resources
Table of Contents
Section
1.0 PURPOSE AND GOALS OF THE APPENDIX
Page
G-l
2.0 ISSUES AND TERMINOLOGY ................................ ,.* ...... G-l
3.0 AFFECTED ENVIRONMENT DESCRIPTION ... A :|Sft|i! G-3
3.1 Fish 'Sflll^N, G-5
3.1.1 Distribution, Abundance, and Composition .... .^^jgjjj^^.t G-5
3.1.2 Adult Spawning Counts Jil -;;,.* ... ^";%?llt% ' G-9
•"•,•''.<•'- -•-••"• '">• ^W^is^'^ * &&*<>
31 '•» T"** l TP* ;/:iiSi.'.v. <-'"/-•.. •' •si^lsiils'®'? S ^*^^ * <^^ y\
.1.3 Fish Tissue ffe... • • -«- ^Ifs -. - • **• • G-9
3.2 Benthic Macroinvertebrates X .• A ... G-10
3.3 Amphibians G-12
3.4 Aquatic Habitat and Riparian Zone G-13
4.0 IMPACT ASSESSMENT
4.1 Water Quality Impacts
4.1.1 Comparisons to Aquai
4.1.2 Toxicity Studies .
4.1.3 Macroinvertebrate
4.2 Sedimentation ... .M g. G-18
4.3 Habitat Alteration .. jfv. A G-18
4.4 Hazardous Materialjplls : G-19
G-19
G-21
5.0
Criteria G-15
G-21
THERWPORMATION SOURCES G-27
brmation G-27
brmation G-27
c Life Water Quality Criteria G-27
List of Tables
of Fish Sampling Techniques G-8
G-i
-------
Region 10 Mining Source Book
Appendix G — Aquatic Re
1.0 PURPOSE AND GOALS OF THE APPENDIX
In the Pacific Northwest and Alaska, freshwater aquatic resources often represent an
important component of the environment that must be considered in impact assessments for
mining projects. Freshwater aquatic resources that typically are addressed in a NEPA document
and baseline studies include fish, benthic macroinvertebrates, and physical parameters that define
habitat for these communities. These aquatic resources, especially fish, often represent
significant issues for the proposed action being evaluated during the NEPA process?"
/
The purpose of this appendix is to provide a summary^ the types'of information needed
to characterize freshwater aquatic resources within the prpj^lkudy area and describe methods ,,,.
that can be used in analyzing impacts of mining projects|0i freshwater aquatic communities and
their habitat. The remaining portions of this Appendix Jtbvide information on Issues and
Terminology (Section 2.0), Affected Environment DesllBtion (Section 3.0),
(Section 4.0), and Literature Cited (Section 5.0). Con
topics discussed in this Appendix are included in Section
er information soirees for the
When conducting NEPA impact assessments f6%nining^p^Rtspconsiderable overlap
exists between aquatic resources and surface water awl-ground wli|||pility and hydrology.
Descriptions of methods for conducting NEPAanpa*assessments otfhydrology, sedimentation,
and surface and ground water quality are provided in tefgejtSs%. A, fjljffrolQgy, Appendix B,
Receiving Waters, and Appendix H, Erojjjtm andSe3' " '* *******'
This appendix addresses on
mining operations in EPA Regioi
mineral deposits are inland, an
some cases^jmcluding c
effects resoi
or indirect!"
twater aquatic resources. Most of the direct impacts of
to freshwater resources, simply because most mines and
;harges to marine^pkironments are generally prohibited. In
there a^efiatfsftafc anadromous fish, there would be indirect
»ugh no6co^pavin this appendix, NEPA analyses should
yoe environment and marine aquatic resources, whether direct
fOLdGY
Resident and ana||pl|pfs fisheries that are located within a mining project study area
sent a concern to \jjl public and governmental agencies such as the National Marine
ries Service (NMjfiS), the Bureau of Land Management (BLM), the U.S. Fish and Wildlife
(USFWS),Jf|Fu.S. Forest Service (USFS), the U.S. Army Corps of Engineers (USAGE),
, and appropriate state organizations. Fish species, particularly
f'and salmon), are important because of their recreational, commercial, and/or
r/
ery value: Numerous species also are listed as threatened or endangered (T&E)
under the Federal Endangered Species Act or related state statutes. The USFWS, NMFS, and
appropriate state agencies should be contacted as part of the scoping and issue identification for a
particular project to obtain a list of Federal and state listed species. The USFS also uses
important fish species (usually salmonids) as Management Indicator Species. These species
should be included in the NEPA analysis for projects that are located on USFS land.
G-l
-------
In addition, the Magnuson-Stevens Act requires Federal lead agencies to consult on
Essential Fish Habitat1 (EFH) that is established by the appropriate fisheries management council
and NMFS, as identified in their fishery management plans. The Act is a mandate to conserve
marine habitat, but it also includes freshwater habitat for anadromous fish species. In a
regulatory context for conserving fish habitat, the Act requires Federal agencies to consult with
NMFS when any activity proposed to be permitted, funded, or undertaken by a Federal agency
may have adverse impacts on designated EFH. If a project may have adverse effects on EFH,
NMFS is required to develop EFH Conservation Recommendations, which will include measures
to avoid, minimize, mitigate, or otherwise offset adverse effects on EFH. The consultation
process for EFH will be incorporated into interagency procedures previously established under fe,
NEPA, ES A, Clean Water Act, Fish and Wildlife Coordination Act, and at^ettiber applicable Jr
statutes. / \;f» , ?''
/
f
"•*,
Benthic macroinvertebrate communities represent atoimportant biological component of
the aquatic environment, since they provide food sources forfeit and are indicators of water
quality and habitat conditions. ''"' „
f
The Clean Water Act (CWA) directs the EIJAaad states
programs that evaluate, restore, and maintain the cle^a^t|)hysical,*ap^i%iological integrity2.
States adopt water quality standards to prote^publi©|pe«8tfa«aad welfare, enhance the quality of
A i ^ *• £*# *• X-vV* >
water, and protect biological integrity. In>general teftms',, a watearfp^ality standard defines the
goals of a water body by designating th&use or usfes to be madj^of the water, establishing criteria
necessary to protect those uses, and^reventingidegradatioH^of water quality through
antidegradation provisions. The fi^lfmacroinVertebrat^ and periphyton (attached algae)
assemblages are all direct measures of the beneficial use%ider the CWA. The CWA applies to
all species of aquatic life including, but not limitei^b', "important" fish species.
"
After reviewing the proposed mining plan for a particular project,, the potentially disturbed
or impacted areas should be related to the presence of fish species, macroinvertebrate
communities, and habitat conditions (including riparian and hyporheic zones) within the project
study area. Potential aquatic resource issues for mining projects include:
?• / ~ <<*
•'•&r
• Potential adverse effects on water quality and aquatic communities and habitat due to
sedimentation, metals, acid generating materials, and other toxic chemical loadings.
.=>|;.: • Potential effects of transporting and storing fuel and other toxic chemicals that could
pose riskof spills and adversely affect aquatic communities and their habitat.
•-•«»; . Potential' water use by mining operations that may affect flows in project area water
, bodies, which could adversely affect habitat for important fish species and
1 Essential Fish Habitat is defined as "... those waters and substrate necessary to fish for spawning, breeding, feeding, or growth
to maturity."
- Biological integrity is "a balanced, integrated, adaptive community of organisms having species composition, diversity, and
functional organization comparable to that of natural habitat of the region" (Karr and Dudley 1981).
G-2
-------
Region 10 Mining Source Book
Appendix G - At
macroinvertebrate communities.
Potential direct disturbance to habitat used by important fish species during life
history events such as spawning, rearing, and adult movements.
These issues are discussed in more detail in Section 4.0.
3.0 AFFECTED ENVIRONMENT DESCRIPTION *
* """
t
The initial steps in describing an affected environment include: (1) define the study area
and (2) collect and review available information on aquatic resources thatare located within the,r
project study area. Information in this appendix focuses on'specific aspects of the data collection
and review task for aquatic resources and a summary of methods that can be used in conducting
additional baseline studies. 'v , -*" ' We*
The affected environment description should characterize important information on fish
communities, macroinvertebrate communities, amphibians and?qtiier aquatic and semi-aquatic
vertebrates, and aquatic habitat, including the adjacent'ripariari^X^e, within the project study
area. Fish and macroinvertebrate assemblages arejtefefied as an ass@scila*3BS of organisms in a
^™*^ .-^i^isii^P ^\"4 & ^** f'f^^ *-^
given water body (EPA 1996). The study area^^^pii^sources should include potentially
affected watersheds. The study area shouldp^oip^m^^eyjprqi^t'area boundary) and off-
site (both upstream and downstream) warft>odiesjprd zones that receive both
direct and indirect impacts. The level «detail be commensurate with the
importance of the impact (Council^mvironn&tal Quajjly, 1986). The following types of
information are typically neededJiMaracterJ|l'aquatic^jplource topics for the Affected
Environment Section of a NEPJIIocument
latic Ve
lAsseml
'included). This includes any other aquatic vertebrate species
%>e collected in conjunction with the fish.
|ndance,^nd composition of game fish and T&E and candidate
x-j
e, and composition of amphibians and other aquatic and semi-
aquatic vert^fi|pr (including aquatic mammals and reptiles)
List of any jiitical habitat designations for T&E species, as established by the
USFWS and/or state agencies.
List otJBiy Essential Fish Habitat established by regional fisheries management
council.
•2f Seasonal timing of spawning for game and T&E and candidate species.
^Riparian is a term that refers to "plant communities contiguous to and affected by surface and subsurface hydrologic
features of perennial or intermittent lotic and lentic water bodies (rivers, streams, lakes, or drainage ways). Riparian areas have
one or both of the following characteristics: 1) distinctly different vegetative species than adjacent areas, and 2) species similar to
adjacent areas but exhibiting more vigorous or robust growth forms. Riparian areas are usually transitional between wetland and
upland" (USFWS, 1997). Riparian areas also often include wetlands.
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Appendix G — Aquatic Resources
In addition, the Magnuson-Stevens Act requires Federal lead agencies to consult on
Essential Fish Habitat1 (EFH) that is established by the appropriate fisheries management council
and NMFS, as identified in their fishery management plans. The Act is a mandate to conserve
marine habitat, but it also includes freshwater habitat for anadromous fish species. In a
regulatory context for conserving fish habitat, the Act requires Federal agencies to consult with
NMFS when any activity proposed to be permitted, funded, or undertaken by a Federal agency
may have adverse impacts on designated EFH. If a project may have adverse effeclfe'on EFH,
NMFS is required to develop EFH Conservation Recommendations, which wiM, include measures
to avoid, minimize, mitigate, or otherwise offset adverse effects on EFJiplie'Consultation
process for EFH will be incorporated into interagency proj|ples previoto^e^ablished under ^
NEPA, ES A, Clean Water Act, Fish and Wildlife Coord«Son.
statotes- ,1. >'
Benthic macroinvertebrate communities repfesei
the aquatic environment, since they provide food source!
quality and habitat conditions.
^rtant biological of
id are indicators of water
states
ihysic
id wel
The Clean Water Act (CWA) directs the El
programs that evaluate, restore, and maintain^
States adopt water quality standards to
water, and protect biological integrity. ]jj|pneral
goals of a water body by designating or ujpi to water, establishing criteria
necessary to protect those uses, an^i^entingJigradatioAf water quality through
antidegradation provisions. The^^macrq^prtebrate^id periphyton (attached algae)
assemblages are all direct measJ|f of the the CWA. The CWA applies to
ad implement
biological integrity2.
:, enhance the quality of
liry standard defines the
all species ofaquatic life ii
|g, but nc
"important" fish species.
or impacted!
communities,
study area.
;resoi
-»WB3&i8«=>""
lining plan for a particular project, the potentially disturbed
j|e presence offish species, macroinvertebrate
iding riparian and hyporheic zones) within the project
ssues for mining projects include:
Potential aoKe^e^Wcts on water quality and aquatic communities and habitat due to
^•'''^'-'Xi? :-;,~^^.;^
sedimentati^n;?£ptals, acid generating materials, and other toxic chemical loadings.
Potential effects of transporting and storing fuel and other toxic chemicals that could
pose risk of'spills and adversely affect aquatic communities and their habitat.'
Potentialjwater use by mining operations that may affect flows in project area water
bodies, which could adversely affect habitat for important fish species and
1 Essential Fish Habitat is defined as"... those waters and substrate necessary to fish for spawning, breeding, feeding, or growth
to maturity."
2 Biological integrity is "a balanced, integrated, adaptive community of organisms having species composition, diversity, and
functional organization comparable to that of natural habitat of the region" (Karr and Dudley 1981).
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Appendix G — Aquatic Resourc
macroinvertebrate communities.
• Potential direct disturbance to habitat used by important fish species during life
history events such as spawning, rearing, and adult movements.
These issues are discussed in more detail in Section 4.0.
3.0 AFFECTED ENVIRONMENT DESCRIPTION
The initial steps in describing an affected environmentunclude: (l)4efirie the study area
and (2) collect and review available information on aquatic resources that arfe located within the,
project study area. Information in this appendix focuses^r%>ecific aspects of ftexdata collection
and review task for aquatic resources and a summary ofinethods thatcan b£u§gdm conducting
additional baseline studies. /*
The affected environment description should cl
communities, macroinvertebrate communities, amphib|j
vertebrates, and aquatic habitat, including the adjacent
area. Fish and macroinvertebrate assemblages i
given water body (EPA 1996). The study area
affected watersheds. The study area shouldpiom
site (both upstream and downstream) wajp^odies
direct and indirect impacts. The level jjpaetail aj|ranalys
importance of the impact (Councilmvironital
information are typically nee
Environment Section of aNEP
Fi
'Ortant information on fish
iuatic and semi-aquatic.
hin the project study
of organisms in a
include potentially
area boundary) and off-
ian zones that receive both
"to be commensurate with the
, 1986). The following types of
iource topics for the Affected
led). This includes any other aquatic vertebrate species
collected in conjunction with the fish.
Id composition of game fish and T&E and candidate
ice, and composition of amphibians and other aquatic and semi-
i (including aquatic mammals and reptiles)
List of any Jptacal habitat designations for T&E species, as established by the
USFWS jsp/or state agencies.
List o£«y Essential Fish Habitat established by regional fisheries management
/«
(SL-
onal timing of spawning for game and T&E and candidate species.
^Riparian is a term that refers to "plant communities contiguous to and affected by surface and subsurface hydrologic
features of perennial or intermittent lotic and lentic water bodies (rivers, streams, lakes, or drainage ways). Riparian areas have
one or both of the following characteristics: 1) distinctly different vegetative species than adjacent areas, and 2) species similar to
adjacent areas but exhibiting more vigorous or robust growth forms. Riparian areas are usually transitional between wetland and
upland" (USFWS, 1997). Riparian areas also often include wetlands.
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Appendix G — Aquatic Resources
• Habitat requirements of game and T&E and candidate species.
Fish Tissue Contamination Information
• Species, type of sample (i.e. whole fish, fillet), and number of samples; and
• Metal concentration in sample. .
Macroinvertebrate Assemblages Information
• Enumeration and identification of benthic invertebrates
level (Plotnikoff and White 1996).
• Community metric data (e.g., total number g|p&a, perce
taxonomic
Plecoptera taxa, number of Ephemeropterajjfca, and njplber ol
4r
w ^
id Aquatic/Semi-.;
^number o|tf"
*•". V /. >s.^
i^i-
Information on Other Aquatic Organisms (An
Mammals)
• Species composition and abundance.
• Habitat requirements and seasonal timji
Lbreedir
Habitat Information
Streams - Gradient, widrnsjtid depthj^pool
streambank erosion, barrie^and/or n
large woody, debris, irndiJIut banks^
temperature, and displved o>
f, substrate composition,
crossings, culvert characteristics,
face fins, flow characteristics,
Lakes and Re;
': '"A.
lyjej^etation,
estimated shade
\ «t
TOST •• *
littoral zone area, presence of aquatic
rcent cover and composition of vegetation by strata, and
;asons.
Project scoping and discussion^ with Federal and state agency biologists should be used to
define the specific list<€lppics to be covered as part of the Affected Environment Description.
Sources of information^: tfie^aquatic resource topics can be obtained by searching published
literature, unpublished agency file information, and contacts with relevant Federal and state
agencies. J|
:;.i 4
\j Summaries ofiecommended methodologies to collect baseline data, if needed, are
provided below.*The summaries focus on field studies for fish, benthic macroinvertebrates, and
habitat characterization. For topics such as the life history and habitat requirements offish,
sufficient information is usually available in published literature. Prior to initiating any baseline
studies, the proposed methods should be discussed and approved by appropriate Federal and state
agency fishery biologists and/or aquatic ecologists.
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Appendix G - Aquatic Rest
3.1 Fish
3.1.1 Distribution, Abundance, and Composition. The timing and frequency offish surveys
largely depend upon the extent of migration or movements exhibited by the important fish
species. If the important species are resident (i.e., minimal movement or migrations), one
sampling effort in the summer or fall should be adequate to characterize composition and
abundance. Additional sampling efforts may be needed to characterize composition and
abundance information for more mobile species. If spawning informatMmjs needed, one survey
should be scheduled to coincide with the peak spawning period for species. It also
is important to note that surveys of downstream, and in so^ne areas may be
appropriate. This is true even if no fish reside within or jnigrate boundary.
Final decisions on the timing and frequency of surveys sffeuld be ;with
the appropriate agency biologists.
G-l for me
The selection of a sampling method to collect dat
composition offish communities depends mainly upor
technique has limitations in terms of its effectiveness'
and life stages offish species. In streams and si
backpack or shoreline electrofishing, snorkelij
methods, electrofishing is the most commoj
completing the survey. However, electrc
the Pacific Northwest that contain fede
deeper rivers, boat electrofishing;
collecting methods for lakes or i
seine nets. Collection permits airequirec
wildlife agencies for all of
istribution, abundance, and
:er body. Each sampling
f habitat and behavior
ods include
LOW seining. Of these
time efficiency in
i some watersheds within
salmon or trout species. In
to collect fish. Possible types of
•ofishing, gill nets, fyke nets, and
S, NMFS, and/or state fish and
g. Applications of the various fish
in and life stage are listed in Table G-l. Brief
are provided below; refer to literature citations in Table
:descrr
sampling methods.
and rivers with depths less than about 3 feet,
ion method used to collect adult and juvenile fish by producing
an elejllIEal field in addition, some amphibians may be collected along with the
should be identified as well. The method is not effective in capturing
saifhsized fish (i.e. yojjfg-of-the-year) because of their relatively small surface area. Prior to
Iting the survey, tJjPsampling effort is quantified in terms of linear distance, stream area
i, or duratiojpl sampling in minutes. The crew moves in an upstream direction and
3tes within the reach. All fish species are netted and then processed in the
ig and enumerating each fish by species. Species identifications should be
mSiStpPtiuaiified fisheries biologist and/or voucher specimens checked by a fish taxonomist at
a university, college, or museum. If population studies are required, the upper and lower ends of
the sampling reach are blocked off with nets. Multiple passes through the reach are usually
required for estimating fish population numbers.
Shoreline Electrofishing. Shore-based electrofishing can be used in larger wadeable
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Appendix G — Aquatic Resources
with depths
in
streams and rivers, where backpack electrofishing produces an electrical field that is too small
and weak to be effective. In shore-based electrofishing, all equipment (electrical unit and
generator) is located on land, except for the lead electrode. A two or three-person crew
electrofishes the sampling reach in the manner as described above for backpack electrofishing.
Boat Electrofishing. A fiat-bottomed boat equipped with electrofishing equipment can be
used to collect fish in slow-moving rivers and standing water environments. The boat design
consists of a forward deck that can accommodate two standing adults as dip-nette||iand one or
two booms that extend forward from the bow with an electrode. The sai||)lin|Ji6cedure
involves slow operation of the boat in an upstream direction^long
less than approximately five feet. Fish are netted as they are-stained^
collecting containers. Field processing is similar to backjpck electrof
Snorkeling. As part of the R1/R4 Fish Habitat It
land in the Pacific Northwest, direct counts of game an|
(Overton et al., 1997). This technique is not recommenc
since some of the small non-game species can be difficj
snorkelers count all fish in a single pass within the sti
this technique include: (1) stable flow periods
sunlight conditions between late morning
exceed 9 °C; and (4) visibility should be
entire habitat unit or a portion of the unit
the center of the unit and count fish
bank and count all fish towards i
(3) float downstream along the
the
Weir.\This techniq
pf the s;
IW juvel
''^''-*&r~'^'-'^\
to streams amlsiajal! rivers
and tendency fepi^vpth debris?
Minnow Trapsv
conical-shaped funnel
edures thatmejifsed'on tJSFS
are made by snoikeimg
assemblage characterization
Typically, one or two
criteria required for
.ber; (2) direct
inperatures should
are counted in the
ipproaches: (1) proceed up
banks; (2) proceed up one
deep or turbulent to zigzag; or
water.
&&
bf a temporary or permanent barrier across
tp. Weirs are best suited for capturing
moveup or down streams. The use of weirs is limited
instruction expense, formation of navigation barriers,
ible trap captures juvenile fish as they enter through a
The traps are usually baited with fish eggs when they are
used to collect juvenile saSpL Typically, the traps are scattered along a stream or river segment
and fished for at least 12 to 24 hours.
Seining. Appropriate-sized seine nets also can be used in slow-moving sections of streams
or shallow rivers to collect young-of-the-year and juvenile fish, if bottom substrate is relatively
smooth and free of debris and other snags. Beach or haul seines are constructed of mesh panels
hung from a float line with a weighted leadline attached to the lower edge. A mesh bag is often
attached to the middle of the net, which collects fish as the seine is dragged along the bottom by
two people.
Hoop Nets. This entrapment device is a cylindrical or conical net distended by a series of
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Region 10 Mining Source Book
Appendix G - Aquatic Resources
hoops or frames. The net has one or more internal funnel-shaped throats whose tapered ends are
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Appendix G — Aquatic Resources
Table G-l. Summary of Fish Sampling Techniques
General Type of Water Body/
Sampling Gear
Streams/Shallow Rivers
Backpack electroshocker, shore-based
electroshocker
Snorkeling
Seine net
Minnow trap
Weir
Ground survey
Aerial (helicopter) flyover
Types of Information
Species List
X
X
X
X
Distribution
X
X
X
X
Abundance/Composition
X
X
X
X
§
'i
!•
X
X
Adult Spawning Counts
X
X
Salmonid Life Stages
j3
1
X
X
X
X
X
Juvenile
X
X
X
X
X
Young of the Year
X
X
References -
Descriptions of Sampling Methods
Nielsen and Johnson (1983); Klein m et al. (1993)
Overton et al. (1997)
Nielsen and Johnson (1983); Klemm et al. (1993)
Nielsen and Johnson (1983); Klemm et al. (1993)
Nielsen and Johnson(1983); Klemm et al. (1993)
See Section 3. 1.2
See Section 3. 1.2
Deep Rivers (Moderate Velocities)
Hoop net
X
X
X
Deep Rivers (Low Velocities)
Boat or raft electroshocker
X
X
X
X
X
X
X
Nielsen and Johnson (1983)
Nielsen and Johnson (1983)
Lakes, Reservoirs, and Ponds
Boat electroshocker
Fyke net
Gill net
Seine net
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Nielsen and Johnson (1983); Klemm et al. (1993)
Nielsen and Johnson (1983); Klemm et al. (1993)
Nielsen and Johnson (1983); Klemm et al. (1993)
Nielsen and Johnson (1983); Klemm et al. (1993)
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Appendix G — Aquatic Resourc
directed inward from the mouth. In riverine habitats, hoop nets are set with the mouth opening
downstream and sufficient depths to cover the net. Hoop nets are usually baited and fished for at
least 24 hours. This method is selective for bottom-feeding species such as carp, catfish, and
suckers.
Fyke Nets. This entrapment device is a modified hoop net with one or two wings or
leaders of webbing attached to the mouth to guide fish into the enclosure. Generally, fyke nets
are set in shallow areas of ponds, lakes, or reservoirs, with sufficient depths to covefthe top f the
net. Fyke nets are selective for certain mobile, cover-seeking species su|h as sjjnfishes and pike.
Gill Nets. This entanglement gear consists of verti
out in a straight line in lakes, reservoirs, and ponds.
captured
netting and become entangled in the mesh. Gill nets cajpe set in realty dirt!
are typically set
into the
depending on the species desired and types of habitats wateiPoody. A vl
can be captured by gill nets, but the gear is most effectMi^^^cies that i
daily movements. This collecting method usually although juveniles can be
captured if smaller mesh sizes are used.
to freshwater
sr
"overs.
3.1.2 Adult Spawning Counts. The number of s
streams or rivers can be estimated by ground q
are applicable in clear streams with depths
are conducted by flying just above tree hdpit aloni
and location of salmon. A sufficient njjjlber of sjleys
spawning period for each of the sahA^speciesw'or effe
should be mostly sunny and cleaj^&eund of sp
number of salmon that reach the^^awninreas in
along the steam and countjite
the returned to their spawning areas.
These methods
Helicopter surveys
bserver records the number
conducted to cover the peak
ecounting, weather conditions
:g salmon can be used to census the
nage. One or more observers walk
mon. The survey needs to occur during
3.1.3
baseline
contaminatiq
jG$$n$i&
concentraJpnTin
Numej|pl problems
basejfie sampling pro
jngful tissue(s) an;
ies, numbers, an4
Concentrations in fish tissue can provide important
round levels in the project study area. If metal
r
s iden^KTas an impact issue, it is important to determine
priorto the initiation of a new or modified monitoring activity.
^ encountered during the design and implementation of a
ish tissue analyses. Problem areas include definition of the most
s for study, difficulties in collecting the desired samples (i.e.,
_5 _________ ; ___ _. __;s), proper handling and preparation of samples without contamination,
ic interpretatio^lT results. Metals are not evenly distributed among different specimens or
or tissues. Natural variation in metal concentrations also typically exists
„_ due to a variety of reasons such as movements, feeding habits, and
Differences. Therefore, a relatively large number of replicates should be collected,
r-j^^v— .
if possible, to statistically differentiate various fish populations inhabiting the study area.
The final design for a fish tissue sampling study should be determined through discussions
with the appropriate Federal and state agencies. Decisions need to be made regarding the
sampling locations, target species, number of replicate samples, composite or individual samples,
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Appendix G - Aquatic Resources
and tissues or organs to be analyzed. The types of tissues that are typically analyzed for metals
include liver,- gills, muscle, and whole body. Fish can be collected using any of the methods
discussed above. Hook-and line method also is sometimes used to collect fish for tissue
analyses.
Specific field and laboratory procedures have been developed to analyze metal
concentrations in fish tissue. Field processing techniques, which are described in EPA (1980),
involve decontamination of the sampling equipment, double wrapping the fish or,jfisue in 5
percent nitric acid-rinsed aluminum foil, and then placing the samples QJ|ice dapSSg the time of
sampling. At a minimum, samples should be kept on ice fbr^o more,^p|^piburs. Fish or
tissues should be frozen prior to shipment to a commercia^pkatorffe|^^gal analyses. The
procedure for decontaminating sampling equipment conjfps of the initial,,
rinse with tap water; (2) wash with biodegradable deterjf
rinse with 5 percent nitric acid; and (5) final rinse wit
removed from the whole fish in the field or in the labor
each decontamination procedure and field processing of
/ith
fwater. TisV
tex gloves for
le and then discarded.
Additional field data that are recommended foneSch fisnl
weight (in grams), length (in millimeters), and tfansBKal of sc
important that the laboratory selected to perfo
including Quality Control/Quality Assuran
3.2 Benthic Macroinvertebrates
Both quantitative and semji
composition data for macroinvejiprates.
scope and purpose of the
^ f /.- $•* ;^^ A x.7SA^^^^^*?33^^^ 4
their appropMateness for
•*• -,^v*i*;&»r,%:« "^
new
given the
to identify any*
other methods^
plude measurements of
(determination. It is
i these procedures,
ight
icthods am used to obtain abundance and
jggiijjjf
pling ^^Kods should be selected based on the
ata should be reviewed for accuracy and
$he objectives. 'The design of any additional or
semi-quantitative or quantitative methods are appropriate,
|iture of data from previous investigations (for example,
iate to use the same methods as earlier studies even if
plete information).
Semi-quantitativeltti^i^typically consist of kick net samplers in streams. After placing
the net in a riffle or runjlf^^strate material in front of the net is rubbed or agitated to remove
anjmacroinvertebratesJ|The organisms in the sampled area drift into the net. The sampled area
is estimated rather thaaineasured. Data analyses usually consist of relative abundance of the
various macroinvertebrate taxa present in the sample. Many state environmental agencies and
the U.S. Geological ^Survey use this method in their National Water Quality Assessment
Program. The existence of semi-quantitative data from previous surveys make the use of such
methods more appropriate than would otherwise be the case.
*
Quantitative methods are used to provide abundance and composition data per unit area
sampled. The sampling methodology depends upon the type of water body. In riffle areas of
streams or rivers with depths less than about 18 inches, sieve-type samplers (either Surber or
Hess) are the most common devices used to collect macroinvertebrates. The Surber sampler
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Appendix G — Aquatic Resources
consists of a 1 square foot frame (0.09 square meter) with an attached net and bucket (0.5
millimeter mesh). The Hess sampler is a circular frame with an attached net (0.5 millimeter
mesh) that encloses a surface area of approximately 1 square foot or 0.1 square meter. Both
methods involve the removal of macroinvertebrates on substrate surfaces by hand. All collected
material then is washed and concentrated into the bucket and placed into a labeled sample jar and
preserved with formalin and ethanol. Field collection techniques for these methods are described
by the following authors: Surber sampler (Surber, 1937; Hughes, 1975, Klemm et al., 1990) and
Hess sampler (Hess, 1941; Waters and Knapp, 1961; Jacobi, 1978).
.«s..; jKs^i, .ft;-
Quantitative sampling in deeper rivers, lakes, reservoiss, or poni&Saeeomplished using a
_ __ Ait!:, ^SejfaWSSBSSy."-. r °
laterial
grab-type device such as a petite Ponar, Peterson, or EC.
to penetrate the substrate and then enclose bottom subs
gravity-operated mechanisms. The Eckman grab is re
consisting of sand, clay, silt, and organic material. Fo:
grabs such as the petite Ponar or Petersen are used.
grab sampling is to penetrate the bottom material and 00
sampler. The surface area sampled ranges from 0.25
petite Ponar to approximately 1 square foot (0.09 squSPe* met
Descriptions of sampling techniques for these gra^^^riers are
Elliott and Drake (1981), Lewis et al. al. (19
Bfplers are designed
ng- or jjf
bottoms
' **$*" *
and coars^^^py heavier
iportant criterionm effective
etc closure of the sides of the
square meter) with the
eterson sampler.
Weber (1973),
^*USGS&
The design of a macroinvertebrate^mpling^
encompass areas potentially affected or:
site, which is located outside the inJiMitce of 1
exhibits similar habitat conditio:
similar habitat conditions, the idfpficatiogiltpossit
macroinvertebrate commi
re mir
lining
aredJPiownstre
P"
"select sampling sites that
ations. If possible, a reference
vities, should be selected that
sites. By comparing sites with
uses for differences in
Two to four replicate samples
•quality
reqi
Two sampl
macroinvertef
previous sai
the datesjilluch;
sufficient data for statistical analyses, if
effort should be conducted in the summer or early fall.
tor fall) would account for seasonal changes in
from developing young and adult hatching. If
^additional sampling should be scheduled to coincide with
Laboratory all samples consists of sorting and picking all macro-
ebrates into a viaMollowed by identification and enumeration of all organisms. If the
lie contains a largJInumber of macroinvertebrates, subsampling of 500 organisms can be
layslip, 199JpPfdentifications should be taken to the lowest possible taxonomic level to
formatiNron the composition and diversity of macroinvertebrates inhabiting the water
Data analyses recommended for a baseline study of macroinvertebrates varies depending
upon whether issues were identified during scoping. At a minimum, the number of taxa,
abundance, and composition data should be analyzed. However, data analyses are recommended
only if at least 50 organisms are present in the sample. Densities are presented as the number of
individuals of each taxon per square foot or square meter; composition is presented as percent of
G-ll
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Region 10 Mining Source Book
Appendix G - Aquatic Resources
each taxon total macroinvertebrate densities at a sampling location. If a more detailed evaluation
of sedimentation or metal toxicity are required, the following additional metrics can be analyzed.
Number of Ephemeroptera (mayflies) taxa.
Number of Plecoptera (stonefiies) taxa.
Number of Trichoptera (caddisflies) taxa, whose absence may indicate metals
contamination.
"^
Percent Dominant Taxon - Percent composition of the most abundanjri&kon in the
macroinvertebrate community at a sampling location. J*.,
Percent Baetidae - Percent composition of baetid,,mayflies (meteiSasitive group).
Species Diversity - Index that indicates taxono^p;richness«ri.d abundance among
the various taxa.
Metal Tolerance Index - Rating system rep||tenting rejative setts:
to metals developed by McGuire (1994) fc^fcsternjiontane stre;
1
Information on how to use metric data in evaluati
stresses within a water body are discussed in Section 4.
of including these metrics in baseline characterizationlPDf mac!
procedures are discussed in Plafkin et al. (1989),
Barbouretal. (1997).
3.3 Amphibians
Amphibians are another gro
widespread declines of amphibi
have been implemented by PacifipNorthw!
Northwest, numerous nativ^^rfiibian s;
species. .Fj|epal agenci^^^^the Fore
_ jt jit;PS'*t*ft. „ %*
as Forest^ei^l^ sp»
In gene:
the Pacific^
all or part of^eirlife
Dicamptodon spp.); am
of mining or other
ssment). For the purposes
ite communities,
man (1996), and
s that injpbit aquatic environments. Due to
onservajpn planning and monitoring efforts
'ederaljpll state agencies. In the Pacific
Id as state "sensitive" or "special concern"
also have targeted certain amphibian species
assemblages are associated with aquatic habitats in
ident species which live in or adjacent to water during
*., tailed frogs, Ascaphus truei, and giant salamanders,
^breeders which require standing water or lentic habitats for
egg-toying and larval devefilpient (Olson et al., 1997). The following information describes the
more common methodsUiat can be used to collect data on species presence and relative
abundance for stream arid lentic environments. Detailed descriptions of these and other sampling
methods can be found in Heyer et al. (1994) and Olson et al. (1997).
VisuaTiiOiservations and Dipnetting. The most common method in determining the
presence and relative abundance of amphibians in both stream and lentic environments involve
visual observations and dipnetting. Species presence and relative abundance can be made by
walking and counting amphibians within defined sections of the study area. If relatively large
numbers of amphibians are encountered, subsampling can be used. Dipnetting can be used to
collect egg masses, larvae, and adults in shallow aquatic areas by making sweeps in front and to
the sides at designated stops. Each scoop should include the upper 2 to 3 centimeters of bottom
G-12
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Region 10 Mining Source Book
Appendix G — Aquatic Resourc
from a sweep approximately 1 meter (3 feet) in length. After each scoop, water and fine
sediment should be strained from the net by gently sloshing it back and forth in the surface water.
The contents should be examined for adult and larval amphibians. If relative abundance is a
study objective, it is important to standardize the distance between stops, as well as the number
and length of sweeps. In this situation, abundance data are presented as the number of
amphibians per area sampled.
A systematic approach in obtaining relative abundance data can be achieved by using
quadrate or transect sampling methods. Quadrate sampling consists of laying out a series of
small squares at randomly selected sites within a habitat typfeand thoroughly searching those
Other commercial traps are available thaj
wire-frame. Traps are sometimes bait
Night Surveys. Since so
conducted using a flashlight
and adults (Qlson et al. I9r~
A
.Vi:
and wet
amphibians
squares for amphibians. In the transect method, narrow st;
and surveyed for amphibians. Patch sampling, which i
can be used to determine the presence and abundance ojj
area (i.e, logs, debris jams, etc.). Detailed descriptioi
etal.(1994).
Funnel Traps. For nocturnal or cryptic species,
due to depth or abundance of vegetation, funnel trappf
of a holding chamber with one or two tapered moj
entrance to the trap ulterior. Onetypeoffunnj
available minnow trap, which is constructe
;ects areJaAJomly layed out
Sdified form of -qwadEate sampling,
tphibiansJn disciete^stdsanits of an'
icse methods are provided byJHeyer
it are difficult to sample
d. Funnel traps consist
toward a small
commercially
:anized hardware cloth.
febbing wrapped around a
ive at night, visual surveys can be
ibian eyes are used to record larvae
Dians can be il
lere amphibie
jnductedoy snorkeling are useful in deep portions of lakes
iit^long snorkeled transects or defined areas. The number of
>f time surveyed.
(, this method is used for fish surveys, but incidental observations
jtlpart of the fish survey. Pools and backwater areas represent the
encountered.
ant
The design andjlection of study sites for amphibian surveys are discussed in detail by
et al. (1997)^^veys should consider all aquatic habitats within a study area that could be
J?y amjgpfans such as streams, rivers, ponds, lakes, meadows, and other wetland areas.
Purveys are required, the surveys must be timed to coincide with the breeding
felopment of the species (spring and summer).
3.4 Aquatic Habitat and Riparian Zone
The level of detail required for characterizing aquatic habitat within water bodies depends
upon numerous factors such as the presence of game fish or T&E fish species, presence of
G-13
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Region 10 Mining Source Book
Appendix G - Aquatic Resources
critical habitat for Federally listed fish species, management goals for aquatic resources
established by Federal and state agencies, types of potential impacts that could result from the
mining project, and the level of concern for habitat impacts as identified during the scoping
process. In some instances, existing habitat information may be available for watersheds that
support game or T&E fish species. The data should be reviewed and determined whether it
would be sufficient to characterize aquatic habitat for the NEPA document. If additional field
surveys are required, methods should be used to allow comparisons to future monitoring
programs or other watersheds. Examples of methods that are currently being used|fe the Pacific
Northwest are summarized below.
Mining projects that are located on USFS land sho
USFS Columbia Basin Anadromous Fish Policy and Imj
Columbia Basin Forests to have comparable data wi
conditions. The Salmon Conservation Strategy (PAC
goals and objectives that help protect, maintain, and re:
these requirements, the R1/R4 habitat procedures were
following parameters are covered in the R1/R4 manual^
discharge, gradient, stream width, stream depth, type
fines, substrate composition, percent undercut b
stability, vegetative cover, and Rosgen chanm
important habitat values for the aquatic enyjj|tBnerii
methods. The
ted
tat
Siethe:
lentation
fasins to ^
useitat
rang
rtant fish habitat^SPfresult of
>y Overton et al. (1997). The
f habitat designation,
Is, percent surface
debris, bank
zone provides
should include
information on width of the zone, percen|$lover and estimated
shaded area. Methods for collecting data et al. (1983), MacDonald
(1991), and Hansen et al. (1995). JM^ design^ baselinfiSiitat surveys for a mining project,
these parameters should be consi^Si^ study dilign should be developed through
discussions with the USFS and specialists.
freq
iber of 1
fin. The
itat
Lalso
icnded by state agencies. The appropriate
|or to designing aquatic habitat studies to determine whether
ardized methods for characterizing habitat in western
Jinns (1982), Platts et al. (1983), Hamilton and Bergen
state
specific
U.S. stream:
(1984),
4.0 IMPACT ASSE:
$0: -sIP?
"* Numerous reviews of the effects of mining on aquatic resources are useful in identifying
potential issues for^mining project (e.g., Martin and Platts, 1981; Meehan, 1991; Ripley et al.,
1995; Wajers?,1995; and Starnes and Gasper, 1996). Environmental impact statements (EIS) or
environmental assessments (EA) that have been completed for similar mining projects also
should be used in the issue identification task. This type of information available from published
literature sources in conjunction with the scoping process are used in identifying specific impact
issues for a project. Potential aquatic resource issues for a mining project may include the
following topics:
• Potential effects of water quality changes on aquatic and semi-aquatic (mammals,
G-14
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Region 10 Mining Source Book
Appendix G — Aquatic Resources
amphibians, birds) communities and their habitat that may result from mine
operation. Parameters of concern may include heavy metals, pH, and acid-generation
materials.
Potential effects of sedimentation on aquatic and semi-aquatic communities and their
habitat due to construction and operation activities.
Potential effects of physical disturbance or removal of habitat on aquatic and semi-
aquatic biota.
Potential effects of spills on aquatic and semi-aquatic biota that may^resblt from fuel
transportation and use (i.e., leaking equipment and refueling) and use^f other
hazardous materials. ^ ^*- <**»•*
Potential effects of flow changes on aquatic h^jf||t and riparian zones and their
respective biota due to water withdrawals.
Potential effects of physical blockages or bailers created>by
'
operation activities on fish movements.
4.1.1 Co,
with mi:
mine
generation
surface waters?
concern for
metals.
The analysis should encompass potential effects
aquatic ecosystem health, and on aquatic and semi-aq
required under NEPA regulations, the impact assess
impacts (Council on Environmental Quality, 1986)
impact assessment must be scientifically acci
methods used in analyzing impacts and malgg'cofil!
document. The following information dejjlnbes
for the various issues listed above.
which can in turn affect
id ecosystems. As
•th direct and indirect
environmental
:egrity. Specific
ferenced in the NEPA
used in analyzing impacts
4.1 Water Quality Impacts
\risons to Aq,
ration,
;ess
tera. Water quality issues associated
activities involve the potential discharge of
IgreasedToads of metals and other toxic pollutants; and the
jt ore, and mine workings. If these pollutants reach
st important aquatic species. Potential analytes of
elude pH, cyanide and associated chemical species, and
factions and/or that can be taken to avoid or reduce water quality impacts from
ig activities are dijpissed in Appendix B, Receiving Waters; Appendix C, Characterization
\e, Waste Rock, ajfTailings; Appendix D, Effluent Quality; Appendix E, Wastewater
* \ent; and Apifflix F, Solid Waste Management.
IF
_^. -ommon approach used to analyze the effects of water quality changes on
lunities is to compare projected post-mining water quality to applicable standards
intended to protect aquatic life. Water quality standards are based on three components:
(1) designated beneficial use or uses of water (i.e., aquatic life use)
(2) criteria designed to protect those uses (e.g., pH)
(3) an antidegradation provision.
G-15
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Region 10 Mining Source Book
Appendix G — Aquatic Resource^
The fish, macroinvertebrate, and/or periphyton assemblages are all direct measures of the
aquatic life beneficial use under the CWA. For many metals, criteria are used to protect aquatic
organisms from both acute4 and chronic5 toxicity. Standards for metals such as cadmium,
chromium III, copper, lead, nickel, and zinc are dependent upon hardness (mg/L as CaCO3),
which is reflected in equations that are used to calculate the criterion for each metal. Toxicity is
inversely related to hardness and EPA typically uses a conservative hardness (5th or 10th
percentile) in determining applicable criteria. It is essential to have representativejjiaTdness data
for the receiving water. The standards for metals also are based on eithj^otal^ebverable or
dissolved concentrations. The standards used (i.e., total recoerable
incorporated into a baseline surface water sampling prograjp
should be
aturaL
The analysis requires close coordination betweex
analyses. The first step in the analysis is to characte
available data. Second, water quality conditions durinj
The final step in the analysis is to compare the pre-mii
concentrations to state water quality standards. It is im
and after mining for both the proposed operation and arnatiR
both qualitative and quantitative) including vario
and other mitigation measures.
If analytes of concern are identifiejjJKr the ]
impacts can be made using available pjjlfished hWarure."
types of effects that the analytes ofjjMlfern majinave on:
communities. If possible, affectejj|pater bodjfpthat
identified in terms of their lenglJiP surfacdlKa.
le surfaceiSAlfier;
Dundee
The|sp|pof sedi:
since standitlillile, not a
background
literature.
levels
for metal coricentratKias
EPA (1994a; 1995);
closure £ggK[)ected.
.-mining water quality
.ate water quality during
jild involve analyses
lagement practices
a qualitative discussion of
;ussion should describe the
and macroinvertebrate
ibit toxic conditions should be
aquatic biota is more difficult to evaluate,
e best approach in analyzing this issue is to compare natural
[uality to benchmark values available in the published
whether the sediment quality is within background
no Kn^pff metal contamination. Examples of information sources
.ent include Washington State Department of Ecology (1991);
. (1996).
4.JL2 Toxicity S/«dies.*Additional site-specific information can be obtained by conducting
toxicity studies using siirface water or sediment from the project study area. These tests can be
used to confirm potential water quality concerns identified as part of the water quality
comparisons between post-mining conditions and applicable water quality standards. Typically,
'Acute toxicity is defined as concentrations that cause mortality or immobilization during a short-term period (usually 48 to 96
hours) of exposure.
4Chronic toxicity is defined as concentrations that cause reproductive impairment or other sublethal effects during a long-term
period (seven days to greater than one year) of exposure.
G-16
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Region 10 Mining Source Book
Appendix G - Aquatic Resources
microcrustaceans (Dapnia or Ceriodaphnia species) and fish species are used as test organisms,
although test procedures exist for a variety of macroinvertebrates such as midges, mayflies,
annelid worms, and amphipods. If additional testing is required, decisions need to be made
concerning the test organisms, type of test (acute or chronic), static or flow-through conditions,
test medium (surface water or sediment), and concentrations to be tested. Mining companies (or
their representatives) are strongly encouraged to consult with the EPA and the appropriate state
agency before designing and conducting toxicity tests. The following test procedures should be
followed for designing and conducting the tests: Jtx s
« -•
• Acute Toxicity - Methods for Measuring the Acute Toxicity-of Effluents and
Receiving Waters to Freshwater and Marine'
• Chronic Toxicity - Short-Term Methods forj
Effluents and Receiving Waters to Freshwa
• Sediment Toxicity and Bioaccumulation - -
Bioaccumulation of Sediment-Associated
Invertebrates (EPA, 1994b) and Standard Tl
of Sediment-Associated Contaminants wit
Society for Testing Materials, 1998).
Additional guidance in designing and o
Methods for the Examination of Water andA
al., 1989).
4.1.3 Macroinvertebrate Metric
for assessing the effects of vario
quality conditions or habitat.
or a sessilemode of life, wj
MacroiraJSltoe asse:
levels
Theevi
pertaining to,
commi
sedi
sof
ben
kesthe
comp
isms (Wt*er;j993).
.ating the»OffOHic Toxicity of JP
Organisms (Lewis^&£19
-------
Region 10 Mining Source Book
Appendix G - Aquatic Resources
and Jackson, 1993; Wisseman, 1996; Fore et al., 1996; and Harbour et al., 1997). Refer to
Section 3.2 for definitions of these metric terms. The final selection of the metric data should be
made through discussions with appropriate Federal and state agency biologists. After completing
the metric data analyses, comparisons should be made between the reference and downstream
sites. Procedures for conducting macroinvertebrate metric data analyses are described by Plafkin
et al. (1989), Wisseman (1996), and Harbour et al. (1997).
4.2 Sedimentation
Several types of analyses can be used to evaluate the
aquatic communities and their habitat. Indicators that c;
sediment-related impacts in streams include change in
For all types of water bodies, aquatic life water quality
sediment-related parameters such as turbidity or total
should be used to characterize the range in values for d
possible, percent increases in these values that could o
be estimated (see Appendix H, Erosion and Sedimenta^
to quantify sediment loadings). The predicted incre
then be related to levels that have been reported asjMgUbig fish
development. For example, percent fines of 4|
adversely affect salmonid fry develop]
1977). Burton et al. (1991) proposed thatfB statis
$fjjljf e&.'%fl&& "'
percent embeddedness should occur injpaho salrjinid re
Sedimentation on
:ential
ddedness.j
tential
,ed to"
it fines oi
dards
idedids
fe of these parairi
alt of project activities should
discussion of methods
h indicators should
2ater reported to
?rnn 1977; McCuddin,
Increase in natural baseline
5itats.
If quantitative predictions pos
analysis should be used to discidSpotentis
published literature.
should be included in thgipliailidiscussic
sediment yieliiasSfesult of ^W_M
J •••! *.-.:••*!,<>• **o.»u xg<^i
grtaquaTf"
environments
|e for thejpliment indicators, then a qualitative
/erse ejects on aquatic communities using
"resulted from similar mining projects
ipact analysis also should estimate the linear
43 Habitat Altera
les/reserwfrs that could potentially exhibit increased
jjvities. The analysis should focus on the affected aquatic
lities and habitat.
'The types of inforMlpn that are needed to evaluate the potential effects of removing or
altering habitat for important game and T&E fish species and other aquatic and semi-aquatic
species include: (1) ideSotify stream segments or water bodies affected by mining activities; (2)
quantify the area of disturbance in square feet or acres; (3) determine list offish species that
utilize the affected areas; (4) characterize the general types of habitat affected; and (5) describe
the fish life stajges (i.e., spawning, young-of-the-year rearing, etc.) that potentially use the
affected areas. The impact discussion should evaluate the significance of altering or removing
the habitat for the important species by considering the magnitude (square feet or acres affected)
and duration of impacts. The use of the impacted area should be related to the amount of similar
types of habitat that are available within the project study area.
Mining activities also may involve the loss of aquatic habitat by physical placement of
G-18
-------
Region 10 Mining Source Book
Appendix G—Aquatic Resources
materials in a portion of a drainage, which may itself need a permit. In this situation, flows are
usually diverted from the "affected stream segment" into a newly constructed channel. The
impacts of removing and replacing stream segments should be quantified in square feet or acres
in relation to the important fish and macroinvertebrate taxa that occur in the affected areas. The
recovery of aquatic communities in the newly constructed channels needs to be discussed using
published studies that have monitored aquatic biota after flow was returned to a stream.
4.4 Hazardous Material Spills
Transportation of fuel and other toxic chemicals to anj from thej|me|&te present
potential risks to aquatic communities from spills that entei^tater bdd^iiiS^ninimum, the
•i'jp.fe^K'S ' "*•'•'".Vv^V'tt''\s'j'-iv!S£j'"
impact discussion should describe the effects of potentiaJSimls on aquaitisiiliiaiinities using-
* * .^-!/V<:** Tffip."y \"-s'^5y fi&y--- , " v^'
available literature on toxicity of fuel and the various cgnicals beki^t-anspWi^daad/or stored
on-site. The analysis should focus on stream segments^^ater^l^ies that arlloca|edad)acent
to and downstream of the transportation route and areas where splftonay occur.
The discussion also should explain that the magnitude of impacts would depend
upon the chemical spilled, volume spilled, toxicity to of year, weather
conditions, and physical characteristics of the water b«Sy. be made to -any
relevant published studies that have conducted afte^^^ar types
A risk assessment may be used to
identified as a significant issue. The foil
risk assessment:
• -Identify the types anjip^es <
and/or are stored si
)etermine the and \
rpm pjielitial spills, if this topic is
ig typically included in a
Sxic cheiilf als that are transported to and from,
sporting toxic chemicals;
ation.roi
js to be analyzed;
important fish species in water bodies located adjacent to
ition:
roads used in transporting toxic chemicals;
of fuel or chemical spills on aquatic species using available
^
in terms of probabilities using vehicle accident data; and
(BMPs) for reducing the risk of spills from transport and/or
Is and toxic chemicals.
id methodology to be used in the risk assessment analysis should be
appropriate Federal and state agencies prior to commencing the work.
fcuments that can be used in designing the risk assessment include EPA (1992; 1997;
1998).
4.5 Flow Alterations
Water use for mine operations could affect flows in streams that contain important game
G-19
-------
Region 10 Mining Source Book
Appendix G — Aquatic Resources
and T&E fish species. Stream flow and water volumes represent an important aspect offish
habitat. These parameters in combination with other factors such as substrate, depth, and
overhanging cover define habitat conditions in a stream.
The type of analysis required to evaluate this issue depends upon the magnitude of flow
change and the presence of important species in the affected water bodies. If flow data are
lacking, studies may be required to obtain the necessary data. In general, key aspects of the data
set (including sources of data, periods of time covered, definitions and descriptiofflliof of data
elements) that is used should be fully described. Mining companies (orJ|eir rjgpisentative)
should contact hydrologists with the lead Federal agency an4appropr|<*
designing flow studies. The simplest approach is to estimateJlhe pe:
affected streams compared to pre-project or base flow coalitions
should be summarized on a monthly basis to reflect an;
movements, or life history information. Using the
should be made to identify the types of impacts on
reduction in flows during the spring would reduce avail;
spawning. Relevant published literature should be usej
could result from flow changes. This qualitative api
result in relatively small flow changes or study arejsist do not
species.
agency prior to
e in flow for the.
low data
asonal
tsoi
iges, a qu
sutic
Sssion
habitat for rainbow trout
I types of impacts that
:or projects that would
ortant game or T&E
If flow alteration is a controversiaLASue method such as the
Instream Flow Incremental Mediodoloi^(IFI\Q«uld oH^^ro quantify the effects of flow
regimes on fish habitat (Bovee, 198J|liiFIM utrazes a hyJSaulic-simulation technique to predict
depths, velocities, and substratesj|pin a reach a^fferent flows. Results from the
simulation are then combined wfe'microha^Bt prefejpiees for the fish species of interest to
estimate the amount of suitable habitat. are expressed in the form of
habitat-suitabiHty curves*!^ tfaetvarious each fish species of interest. Studies have
£&% -*• ^**j&&' ' r^lliiflii'*'!!^
been conducted to develop i^fe*|aiitability curves for a variety offish species (e.g., Bovee,
1978; RaleiglCi982; McMaTMSaleigh et al., 1984; Raleigh and Nelson, 1985; Raleigh
et al., 1986a; 1986b)^ These cure&«jpe used in the habitat simulation analysis. If curves are
lacking for the species of interest, cncves should be developed for the project study area
followingjtechniques desiSibed by Bovee and Cochnauer (1977).
^implementation oftf^IFIM requires the use of a system of computer programs called
PHABSIM (Physical Hipitat'Simulation) (Milhous et al., 1981). The PHABSIM programs
simulate the physical habitat of fish as a function of stream flow and transform the hydraulic
information (depth, .velocity, substrate) into a measure of useable habitat. Field surveys are
required to collect flow, depth, and substrate data along transects established in the streams
affected by flow changes. After the hydraulic simulation is completed, suitability curves for the
target species are used as input to a habitat program, which computes the amount of physical
habitat that is available for each target species at a range of flows. This analysis should be
completed for both pre- and post-project scenarios. The end product is a quantitative estimate of
the change in available habitat in square feet for each target species. A significance level should
be established through discussions with appropriate agency biologists or IFIM specialists to
interpret the results. For example, a 25 percent reduction in spawning habitat for brown trout
G-20
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Region 10 Mining Source Book
Appendix G — Aquatic Resources
could represent a significant impact.
4.6 Obstruction to Fish Movement
If mining activities place materials or structures in a drainage on a temporary or permanent
basis, the effects on fish movements need to be addressed. The initial step in the analysis is to
identify whether important game or T&E fish species exhibit wide range movements in the
affected stream segment. The period of movement then needs to be identified forjeaeh species.
A particularly important period for trout and anadromous salmon speci||as spanning, when fish
migrate to specific areas to lay eggs. Another critical periodjDr salmoliii^i^iigration of
~ s '&"'>»•* ""~' vaa'^y •-"" **>'•/ v-<^'' ^^
juveniles from their nursery streams to the ocean. Blockajpplir obsrfwlttiilbthese movements
•* J^-f-fS^V* ' si'V:>-.,<•! ev~' J :',,;.:.>*W,\ &t~*
need to be identified in the impact assessment. In most ifplnces, prep
to eliminate potential blockages to fish movement.
5.0 REFERENCES
HQJI is required
American Public Health Association, American Watel
Control Federation, 1989. Standard Methc
Waste-water, Seventeenth Edition,
D.C.
.Health.
and Water Pollution
iof Water and
Nation, Washington,
998. S^ard for Measuring the
Contaminants wMFreshwater Invertebrates, Method E
American Society for Testing Materi
j. oxiciiy 01 ocQ.iiiicrii~/A.sso^^*--™.<— vv_—__-_..—_— .._™^_ _ .vv..,.__v_ —. 7
1706-95b. In: 1998Annu^€fokof^MStandfds, ASTM, West Conshohocken,
Pennsylvania.
Barbour,,
jerritse
lent:
|er, B.I
jling, J.B., 1997. Revision to Rapid
M;
EPA/I
rates,
102, Wi
Binns,
& >si
partment, Che
Jse in Streams and Rivers: Periphyton, Benthic
?S. Environmental Protection Agency Report
ilitylndex Procedures Manual, Wyoming Game and Fish
Doming, 209 pp.
, T.C., Brusven, Molnau, M.P., Milligan, J.H., Klamt, C.E., and Schaye, C., 1977.
Transport ofGjjjjinitic Sediment in Streams and its Effects on Insects and Fish, Bulletin
17, Universipif Idaho, Moscow, Idaho, 43 pp.
ijAir
Probability of Use Criteria for the Family Salmonidae, Instream Flow
.^s^jfmation Paper No. 4, U.S. Fish and Wildlife Service, FWS/OBS-78-07, 53 pp.
Bovee K.D, 1982. A Guide to Stream Habitat Analysis Using the Instream Flow Incremental
' Methodology, Instream Flow Information Paper No. 12, U.S. Fish and Wildlife Service,
FWS/OBS-82-86,235 pp.
Bovee, K.D. and Cochnauer, T., 1977. Development and Evaluation of Weighted Criteria,
G-21
-------
Region 10 Mining Source Book
Appendix G — Aquatic Resources
Probability-of-Use Curves for Instream Flow Assessment: Fisheries, U.S. Fish and
Wildlife Service, FWS/OBS-77/63.
Brower, J.E. and Zar, J.H., 1977. Field and Laboratory Methods for General Ecology, Wm. C.
Brown Company Publishers, Dubuque, Iowa, 194 pp.
Burton, T.A., Clark, W.H., Harvey, G.W., and Maret, T.R., 1991. Development of Sediment
Criteria for the Protection and Propagation of Salmonid Fishes. In: BiolQjjazal Criteria:
Research and Regulation of Salmonid Fishes, Proceedings ofa^mpos^n, U.S.
Environmental Protection Agency Report EPA-440/|j91-005^^^0on, D.C., pp.
142-144.
Clements, W.H., 1994. Benthic Invertebrate Commi
Upper Arkansas River Basin, Colorado, Jour
Society, vol. 13, no. 1, pp. 30-44.
Council on Environmental Quality, 1986. Regulations^
Provisions of the National Environmental Polit
40 CFR Parts 1500-1508.
Elliott, J.M. and Drake, C.M., 1981. A
Benthic Macroinvertebrates in Riv
Fore, L.S., Karr, J.R, and Wissemi
Activities: Evaluating Al
Benthological Society, v
Hamilton, K. . Seattle, Washington, Report EPA/910/9-92/013.
: •"*"-•* . - "*#"
Hess, AJ), 1941. New Limnological Sampling Equipment, Limnological Society of America Special
Publication 6, pp. 1-5.
Heyer, W.R., Donnelly, M.A., McDiarmid, R.W., Hayek, L.C., and Foster, M.S. (Eds), 1994.
Measuring and Monitoring Biological Diversity - Standards and Methods for Amphibians,
Smithsonian Institution Press, Washington, D.C., 364 pp.
G-22
-------
Region 10 Mining Source Book
Appendix G — Aquatic Resources
Hughes, B.D., 1975. A Comparison of Four Samplers for Benthic Macroinvertebrates Inhabiting
Coarse River Deposits, Water Research, vol. 9, pp. 61-69.
Jacobi, G.Z., 1978. An Inexpensive Circular Sampler for Collecting Benthic Macroinvertebrates in
Streams, Archives of Hydrobiology, vol. 83, pp. 126-131.
Jones, D.S., Hull, R.N., and Suter, G.W. II, 1996. Toxicological Benchmarks for Screening
Contaminants of Potential Concern for Effects on Sediment-Associated Biot<0996 Revision,
Oak Ridge National Laboratory Report ES/ER/TM-95/R2, Oak pdge, flnnessee.
Karr, J.R. and Dudley, D.R., 1981. Ecological Perspective oa Water Q*
Management, vol. 5, pp. 55-68.
Kiemm, D.J., Lewis, P.A., Fulk, F., and Lazorchak,
Laboratory Methods for Evaluating the Biolo,
Research and Development, U.S. Environmental P
EPA/600/4-90/030.
Klemm, D.J., Stober, Q.J., and Lazorchak, J.M.,
Evaluating the Biological Integrity of Si
U.S. Environmental Protection Agencwcinc
7'MacroinveTW$iiii3iMd and
~>-.S?'}f,fas, ||?*>:i
ijjrity of Surface Wiajii^OfRce of
^5^?\ "* ** *^ .t..'"' y
;ency, Cincinnati, Ohio, Report
Field *md Laboratory Methods for
Office of Research and Development,
|p, Report EPA/600/R-92/111.
Lewis, P.A., Klemm, D.J., Lazorchak^M., W.H., and Heber, M.A.,
1994. Short-Term MethodsMr%stimat^the Chr^^Toxicity of Effluents and Receiving
Waters to Freshwater Editijjjl, Environmental Monitoring Systems
Laboratory, U.S. En^'nmenta^Jroteci^^'Agency, Cincinnati, Ohio, Report
EPAJ500/4-91/002.
Lewis,
MacDonald,
in
*A/910/9
, C.I.,1982. Evaluation of Three Bottom Grab Samplers for
rournal of Science, vol. 82, pp. 107-113.
>
'itorin^Shdelines to Evaluate Effects of Forestry Activities on Streams
\dAiaska, University of Washington, Seattle, Washington, Report
S.B. and Plattff W.S., 1981. Influence of Forest and Rangeland Management on
Anadromous Habitat in Western North America, Effects of Mining, USDA Forest
Service, Pacj^Northwest Forest and Range Experiment Station, General Technical Report
E., 1977. Survival of Salmon and Trout Embryos and Fry in Gravel-Sand Mixtures,
Unpubl. M.S. Thesis, University of Idaho, Moscow, Idaho, 30 pp.
McGuire, D., 1994. Montana Nonpoint Source Water Quality Investigations: 1992
Macroinvertebrate Assessments, Montana Department of Health and Environmental
Sciences, 18 pp. plus appendices.
G-23
-------
Region 10 Mining Source Book
Appendix G — Aquatic Resources
McMahon, I.E., 1983. Habitat Suitability Index Models: Coho Salmon, U.S. Fish and Wildlife
Service Report FWS/OBS-82/10.49, Washington, D.C., 29 pp.
Meehan, W.R., 1991. Influences of Forest and Rangeland Management on Salmonid Fishes and
Their Habitats, American Fisheries Society Publication No. 19, 751 pp.
Milhous, R.T., Wegner, D.L., and Waddle, T., 1981. Users Guide to the P^sical Habitat
Simulation System (PHABSIM), Instream Flow Information Paper No^l f, U.S. Fish and
Wildlife Service Report FWS/OBS-81743,475 pp. A
Nielsen L.A. and Johnson, D.L., 1983. Fisheries Wjjihiques, Anfieriean .Fisheries Society,
' r'^J^ii?" & Ht^^ ^* jK--"
Bethesda, Maryland, 468 pp.
Platts,W3|p!|ahan,
Olson, D.H., Leonard, W.P., and Bury, R.B. (Eds), 1991^
Society for Northwest Vertebrate Biology, Olymf
134pp.
Overton, C.K., Wollrab, S.P., Roberts,
(Northern/Intermountain Regions)
Handbook, General Technical Repo.
Service, Intermountain Research
-»•
r
ig Amphibians in L&me Habitats,
ington, Northwest Fauna No. 4,
1997. R1/R4
rd Inventory Procedures
lent of Agriculture, Forest
Porti
Plafkin, J.L., Barbour,
Rapid Bioassessment Pro
and Fish, U.S.
EPA/440/4-89/001
, S.K., and Hughes, R.M., 1989.
Rivers: Benthic Macroinvertebrates
Agency, Washington, D.C., Report
ishall, GTW., 1983. Methods for Evaluating Stream, Riparian,
Service, Intermountain Forest and Range Experiment
S, Ogden, UT, 70 pp.
Plotnikoff,f;R.W. Sid
-------
Region 10 Mining Source Book
Appendix G — Aquatic Resources
Raleigh, R.F. and Nelson, P.C., 1985. Habitat Suitability Index Models and Instream Flow
Suitability Curves: Pink Salmon, U.S. Fish and Wildlife Service, Washington, D.C.,
Biological Report 82(10.109), 35 pp.
Raleigh, R.F., Hickman, T., Solomon, R.C., and Nelson, P.C., 1984. Habitat Suitability
Information: Rainbow Trout, U.S. Fish and Wildlife Service, Washington, D.C.,
FWS/OBS-82/10.60, 64 pp.
Resh, V.H. and Jackson, J.K., 1993. Rapid Assessment Approacl^^B|dmonitoring Using
Benthic Macroinvertebrates. In: Resh, V.H||ppi ~Ro^^^ffi^M., Freshwat.gr
Biomonitoring and Benthic Macroinvertebrates, Jlfutledge, CMffiilli^Hall, Inc.,
,.,.._.,. -—-—«. " ° > ^ r 'r^'--- " "
N.Y.,pp.40-158.
'I Effects o
Surber,
U.S. Enviro:
Ripley, E.A., Redmann, R.E., and Crowder, A.A., 1995 Jj
Press.
Rosgen, D. L., 1985. A Stream Classification Sys
Management: Reconciling Conflicting Use
and Range Experiment Station, Genera
Jr
Seber, G.A. and Le Cren, E.D., 1967 jffimatir
Relative to the Population, Joujjjal ofAn^^l EcoH
Starnes, L.B. and Gasper, D.C.,
America, Fisheries, vol
. Lucie
Ecosystems and Their
cky Mountain Forest
; pp. 91-95.
eters from Catches Large
: 36, pp. 631-643.
Ining on Aquatic Resources in North
937.
U.S. E^ronmental
Superfimd: Pro
Fauna Production in One Mile of Stream,
: Fisheries Society, vol. 66, pp. 193-202.
9PA), 1998. Guidelines for Ecological Risk Assessment.
.esponse Team, Edison, New Jersey.
;ency (EPA), 1997. Ecological Risk Assessment Guidance for
^Designing and Conducting Ecological Risk Assessments. Interim
Final, U.S. EPApnvlronmental Response Team, Edison, New Jersey.
invironmentai^otection Agency, 1996. Biological Criteria: Technical Guidance for Streams
tion, U.S. Environmental Protection Agency, Office of Water, Office of
H Technology, Washington, D.C, Report EPA/822/B-96/001.
~fJ%&&ffiW£fS0i?™"''
U.S. Environmental Protection Agency (EPA), 1995. National Sediment Inventory: Documentation
of Derivation of Freshwater Sediment Quality, Office of Water, Washington, D.C.
G-25
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ATION
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Mining Source Book
Appendix H — Erosion and Sedimentation
1.0
2,0
3.0
4.0
Table of Contents
GOALS AND PURPOSE OF THE APPENDIX..
H-l
TYPES OF EROSION AND SEDIMENT TRANSPORT |, H-l
2.1
2.2
2.3
2.4
Merrill and Rill Erosion H-2
Gully Erosion jSh H-2
Stream Channel Erosion ... H-3
<:*:&*> v;:*£iif .vx*?rei^3*:: l
Mass Wasting, Landslides and Debris Fl
MINING-RELATED SOURCES OF EROSIO
METHODS TO MEASURE AND PREDICT E
4.1 Gross Erosion
4.1.1 Field Measurements
4.1.2 The Universal Soil
4.2 Sediment Yield ^
4.2.1 Modified and Revised
4.3 Suspended Load
4.4 Software and
4.4.1 DevelopmJPofaC
4.4.2 Anal
U.3
IMENTATldlp
H-4
SEDIMENTATION
........... H-4
........... H-5
........... H-5
........... H-6
............ H-7
uation ............. H-7
............ H-8
n of Sediment Yield H-9
x>del H-10
H-ll
and Geographical Information Systems
H-13
H-13
ATEmOSION AND SEDIMENTATION H-14
Practices (BMPs) Categories H-16
.bilization Measures H-16
Control and Conveyance Measures H-17
et Protection H-l 8
f Idiment Traps and Barriers H-18
Stream Protection H-20
Sediment Detention Basins H-20
innovative Control Practices H-22
7.0 SUMMARY
H-23
H-i
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Mining Source Book
Appendix H - Erosion and Sedimentation
8.0 CITED REFERENCES H-24
8.1 Additional References H-25
List of Tables
Table H-l. Mining BMPs for Control of Erosion and Sedimentation .1 ~,., H-15
H-ii
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Mining Source Book
Appendix H — Erosion and Sedimentation
1.0 GOALS AND PURPOSE OF THE APPENDIX
Baseline knowledge of soil erosion and the subsequent transport and deposition of eroded
sediment into streams and other water bodies is essential to mine planning and operation.
Accurate measurement of natural erosion and erosion from disturbed areas is important to
develop control practices. Significant environmental impacts^ such as ||^|^fievable loss of
soil, or the degradation of aquatic life from the sedrmentatioj|af strea^^p^^wetlands, or
marine estuaries, can be minimized or prevented by empyi^ftontrol|liSi^^r""
Appendix A, Hydrology.
characterize and
usses the design
sto water aquatic resources.
and Jjlier relevant references.
an of both hydrologic
6n control structures at
^^* •
** .dium of methods to measure
sedimentation at mines.
activities.
large-scale e
Operation
preventJSverse effects!
SPORT
3cess that is easily induced and accelerated by man's
fee disturbance of large areas of ground and require
jgetivities
veve
Pexpose large amounts of soil to erosive forces.
> minimize the amount of soil exposed and to reduce or
as or other water bodies from sedimentation.
Soil erosion can* dffined as the detachment, transport, and deposition of soil particles.
Dhment is the dislgping of soil particles from aggregates or soil peds from either rain drop
|t or from the forces of water or air flowing over the surface. Of these, rain drop
his the prii^Jnbrce causing detachment, while the flow of water or air over the surface is
tism for transport. Rain drop splash can also be a cause of soil transport at a
laclean, 1997). Transport by runoff across the surface, therefore, does not
generallyoccur until the rainfall rate exceeds the infiltration capacity of the soil. Once runoff
occurs, the quantity and size of soil particles transported is a function of the velocity of the flow
(Barfield et al., 1981). Transport capacity decreases with decreasing velocity causing deposition.
As velocity decreases, the largest particles and aggregates are deposited first with smaller
H-l
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Mining Source Book
Appendix H - Erosion and Sedimentation
erosive)
particles being carried down slope. Deposition, therefore, usually results in the size and density
sorting of eroded soil particles, with increasingly smaller sized particles being deposited down
slope or down stream. The deposition of detached soil in streams is often referred to as
sedimentation.
2.1 Interrill and Rill Erosion
Erosion occurs on disturbed or exposed areas by ^|prInterill
erosion is sometimes referred to as sheet erosion. The
rain drop impact, where increasing detachment and erosii
and drop velocity. Rills are small channels which for
amounts of runoff. By definition, rills can generally be
from light grading. Larger channels are considered gulli
in rills by the shear forces of flowing water in the rill.
erosion increases as the slope or the amount of surfac;
dominant process on shallower slopes. Surface
primary factors in controlling the degree of ij
area. The amount of vegetation cover is
Vegetation decreases the velocity of i
drop impact. Other measures can 1
erosion. These measures are discu^djin Secjpi 6.0, Be
2.2 Gully Erosion
be ei
events. By €gfiS|ion, gullil
or grading praclipl^
"healing" where5aa&ira|epositio]
-'' ''si& '••>••" Ssfiipr^/•'•^i^-'>T^i''j
of eroded ma^maK%HeMng,is us
ace as a:
ordinary tillage'equipment or
n2.2). Detachment occurs
and the amount of rill
ill erosion is the
e properties are the
curs from an exposed
iurface roughness.
if otects the soil from rain
e roughness and minimize
;ement Practices.
or Siillmtinuous channels that flow in response to runoff
rills in that they cannot be removed by ordinary tillage
>rary feature by being erosively active, or in a state of
the gully is greater than the detachment and transport
y caused by changes in land use that reduce the velocity of
surface runoff, such as applying reclamation measures to increase surface roughness and promote
infiltration. The physicalprocess of erosion in gullies is essentially the same as that described
foErills. Erosion in gullies occurs primarily from the shear forces of flowing water. Foster
(1985), however, indicsled that the amount of erosion from gullies is usually less than the
amount that occurs from rills. This is because the amount of credible particles are quickly
removed from the gully channel, where rills are established on an actively eroding surface.
Therefore, after initial formation, gullies usually serve as a principal transport mechanism for
entrained soils. Gullies can form quickly during extreme events on denuded land and can rapidly
expand TDOth up and down slope (Maclean, 1997). In these cases, gullies temporarily serve as
large sources of eroded soil and sedimentation to water bodies. Uncontrolled runoff and gully
formation can be a large source of transported sediment at mine sites.
H-2
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Mining Source Book
Appendix H - Erosion and Sedimentation
23 Stream Channel Erosion
Stream channels differ from gullies in that they are permanent channels that transport
surface waters. Stream channels can be .perennial, ephemeral or intermittent. In stable stream
channels, erosion and deposition is controlled by the transport capacity <|Ja givejpfream flow,
which is, in turn, governed by the velocity of flow and by local variatiGral^i, slear stress in the
channel. Detachment and entrainment of soil particles wiiy§|ur alo^i^^l^am bed and sides
of a channel when the transport capacity is greater than thjjIISment
Deposition occurs when the transport capacity is less thatfthe sed
As.described hi Section 2.0 above, deposition occurs sthe largpt to the as
velocity and transport capacity decrease. Potential imp^&fa^nine related
channel erosion processes are discussed in Section 3.0.
2.4 Mass Wasting, Landslides and Debris Flow
Landslides and slope failures that create
Laniitides can e>
:esses
sedime
rock debfl
can result in*
existing channj
loading
loads tojiTflood flo\
a*?1
can occur naturally
or can be induced as a result of man's activiti
increases in steep areas containing unstabLdf&ils or
directions. Landslides and slope failurejiSccur
precipitation events when saturatiory^pces theJfKear stre:
failures and landslides can also bejifceed by^pistructio^ictivities that create cuts or slopes
where soils or rock are left steepjifstable ajnfes.
Jides to occur generally
has unfavorable dip
f usually during extreme
fthe soils or rock. Slope
i that e:
idsl
rdebris that are subject to the erosion and
Ides can block stream channels with soil and
jial flooding. The eventual failure of an unstable blockage
juantities of soil and rock debris. Scouring of the
^results from the high flood flows. Additional debris
long the side slopes, adding more sediment and debris
Effects from can be similar to those of landslides. Avalanches can remove
ion, increasing dp erosion potential of exposed soils and rock. Debris and snow from an
ache can tempo^lly block stream channels, creating floods, channel scour, and mass
I along
'WHHiwas, slope failures, and avalanches can create large impacts to aquatic resources.
IncrSsedCTOsion and resulting sedimentation within a watershed can impact spawning gravels,
egg survival and emergence of frye, as well as degrade benthic food sources. Flooding can create
high velocity flows, scour stream banks and destroy gravel substrates either by scour or by burial
H-3
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Mining Source Book
Appendix H - Erosion and Sedimentatior
beneath sediment. Cover created by large woody debris and stable banks also can be destroyed,
which impacts rearing and resting habitat for fishes.
3.0 MINING-RELATED SOURCES OF EROSION AND SEDIMENTATION
Increased potentials for erosion and sedimentation ajt||tines
construction and facility location. Tailings dams, waste ppShd spenj
facilities, or other earthen structures are all potential souifes of sedi
construction, logging, and clearing of areas for buil
soils and increase the amount of surface runoff that and other
bodies. These activities increase the potential for rill and can increase peak
>ose
stream flows, increasing the potential for channel erosio:
stream banks, widen primary flow channels, erode
channels, and alter channel grade (slope). In turn,
degrade aquatic habitats. Channelization can i
potentially affecting fish passage to u]
Poorly designed stream diversions can
in a stream. Increased erosion ups
spawning gravels, egg survival and jsnjrgence oJBrye, as
More detail on these potential im
ateri.
changes^
velocitfl
loderai
high peak flows can erode
and straighten stream
orphology can
•earn reach,
•gence
;. is givej
large embankments can also failjptting ii
for landslides and debris flows. I
L Appenc
its simii
high stream flows.
and alter flow velocities
ition downstream can impact
degrade benthic food sources.
i, Hydrology. Tailings dams and
i those discussed in Section 2.4 above
D PREDICT EROSION AND SEDIMENTATION
4.0
: and control erosion and sedimentation have been
developed by lie^gacult&Sindustry?7 These methods concentrate on predicting gross erosion
and sediment yield from^star||d areas or areas under tillage. This is advantageous for
evaluating and predicting impacts that .result from mining because tillage agriculture and mining
have several similarities ,(Barfield et al., 1981). Both industries can disturb and expose large
areas of ground and both must apply practices to limit or eliminate soil-loss and sedimentation
impact. It should be noted, however, that many mine sites are often located on steeper slopes and
in more diverse topography than agricultural lands. Methods developed for the measurement of
erosion and sedimentation from agricultural lands are generally not adapted or tested for use on
steep slopes. For this reason, appropriate conservatism should be applied when choosing
analytical methods and in evaluating predictive results.
Most methods to measure or predict erosion and sedimentation are designed to predict
either: (1) "gross erosion", (2) "sediment yield", (3) a "sediment delivery ratio", or (4) sediment
H-4
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Mining Source Book
Appendix H - Erosion and Sedimentation
loading in streams. Gross erosion is defined as the total estimated amount of sediment that is
produced from rill and interill erosion in an area (Barfield et al., 1981). The sediment yield from
an area or watershed is the gross erosion, plus the additional erosion that is contributed from
gullies and stream channels, minus the amount of deposition. The amount of deposition that
occurs between the watershed and a down-gradient point of reference is|[uantifje€pusing a
sediment delivery ratio. A sediment delivery ratio can be quairtitativelgpini^lis the ratio of
sediment yield to gross erosion: ~A' * '*
d A is the gross erosion
s. Using
disturbance.
ent elevation.
where D is the sediment delivery ratio, Y is the sedimei
(Barfield etal., 1981).
Few methods have been developed to specifjcjljy or sediment yield
from undisturbed landscapes and watersheds. as well as
methods to analytically predict or model on both
disturbed and on undisturbed areas. For methods that can be
used to measure gross erosion or sedimejiryield areas are outlined
together in this appendix. This sect^Summarj^metho^^raeasure or predict gross erosion,
methods to measure or predict yieldjpcluding sideling, and methods to measure
sediment loads and deposition iniiilams.
iployed to measure the amount of gross erosion which
itershed. A method commonly used, however, is to use
mall pins or stakes are put into the ground to a depth that will
Jon of the top of the pin is surveyed and referenced to a
ference between the top of the pin and the ground elevation below
In is periodically sjiveyed to determine minute changes in elevation. The difference in
i/een sampling events reflects the amount of rill and interill erosion that
:iint. Gross erosion that occurs from a sample plot can be estimated using
several pins. Repeated measurements of water and sediment collected in
stalled hill slope troughs can also be used to detect soil movement and storage
over time.
Tracers have also been used to detect and measure actual soil movement on small plots.
Kachanoski et al. (1992) describe the use of Cesium-137 (137Cs) to detect soil movement and soil
H-5
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Mining Source Book
Appendix H - Erosion and Sedimentation
loss in a complex landscape and to monitor the down-slope movement of soils that occur from
tillage. 137Cs occurs in soils from atmospheric deposition (fall out) that occurred from above-
ground nuclear testing conducted in the 1950s and 1960s. I37Cs tightly binds to soils, is
essentially insoluble and does not leach, and is not subject to significant uptake byjtjants.
Monitoring gains or losses of 137Cs at permanent points can be used to defect mgi|ement of soil.
Other inert tracers can be used similarly.
The above field methods are commonly employedCfor research
land treatment applications or practices are compared. are ofte:
validation or to help calibrate modeled soil losses fromitspeciiic,!
Br"i-S*
be used to detect soil movement and estimate gross erof" '
methods to measure and prejictf
following^
applicable at mine sites because they are not suitable for
sediment yield or sedimentation of streams or other watej
4.1.2 The Universal Soil Loss Equation.
The most commonly used procedure
Equation (USLE), in its original form.
(1965) based on a relationship known Mus;
predicts gross erosion produced by inte2fP erosi°
authors have proposed modificatio^RQ/the to ace
also be used to predict sediment ThesJilodifici
;ere actual
model
can
1 plots, they
, and they do noTpredict
:e Universal Soil Loss
ischmeier and Smith
lusgrave, 1947). The USLE
a field sized area. Several
it for deposition so the model can
will be discussed in Section 4.2 with
LE predicts gross erosion by the
= R * K* LS* C* P
where, A is cojtn|ii§^^Moss area (tons/acre), R is a rainfall factor which
incorporates ramfaH;e3|^^^Qd runoff; K is soil credibility; LS is a dimensionless length slope
factor to account for vat^lp^Jlength and degree of slope; C is a cover factor to account for
the effects of vegetatioril^^^clng erosion; and P is a conservation practice factor. A detailed
discussion of how to calculate, incorporate, and use each of these factors is provided by Barfield
et al.?(1981) and GoldrjSn et al. (1986). The USLE can be used to predict gross erosion from an
area for average annual, average monthly, average storm, and annual return period, or for a single
stornrreturn periodfSependmg on how R is calculated.
Use of the USLE, without modification, at mine sites has several disadvantages. The
calculation does not account for erosion from gullies, or stream channels, or take into account
deposition. It was primarily designed to predict soil-loss from small fields and should not be
used to predict sediment levels in rivers at the drainage basin level. For most applications at
mine sites, the unmodified USLE described above would not provide useful estimates because
H-6
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Mining Source Book
Appendix H - Erosion and Sedimentation
most impact analyses require knowledge of deposition and actual sediment yield from watersheds
or disturbed areas, and calculations of sediment transport in gullies and channels. Consequently,
this method is not recommended, except for calculations of potential soil-loss from a small
disturbed area to aid in the application of best management practices (BMPs) and the design of
other area-specific controls.
4.2 Sediment Yield
Most methods and mathematical models to measlfe or predi
predict sediment yield from an area or watershed. Man!
USLE, described in Section 4.1.2, however, they inco:
erosion from gullies and channels and estimate depositii
streams. The following discussion provides a brief revie^
measure sediment yield and presents a review of mai
predict sediment yield on an area! or watershed basis
4.2.1 Modified and Revised Universal Soil
fods
ques to evalu
n the land surfaceTor in
used methods to
eh have been used to
There have been several proposed modi
predictions of parameters and erosiqi
of sedimentation at mine sites,
Loss Equation (MUSLE) and the
standard USLE model, the:
do not acc
-------
Mining Source Book
Appendix H - Erosion and Sedimentation
analysis requires that large, heterogeneous watersheds be divided into several subwatersheds with
relatively homogeneous hydrologic characteristics and soil types. Consequently, particle size
distribution (i.e., texture analysis) must be measured for the soils occurring in each subwatershed.
The analysis also requires the calculation of a weighted runoff energy term (Q* q^Miat is
computed as a weighted average of the subwatersheds. From particle siz| distortion data, the
median (D50) particle diameter is used to calculate the sediment yield t|^^o,|p*exit each
subwatershed. The weighed runoff energy term is used to roife sedin»|Sfi|ie mouth of the
large watershed or at some point of analysis.
4.3 Suspended Load and Sedimentation
The evaluation of water quality and impacts to
mine sites. Without mitigation and control measures, mi
causing accelerated erosion and sedimentation and
resources. The measurement of sediment load in strj
effectiveness of erosion control measures and
Typically, it is a required component for moj
discussed in Section 2.3, the amount of
depends on the transport capacity, whic
transport capacity increases, the amojjwand parjtlle sizes S^^pended sediment increases.
Transport capacity decreases with^MreashigjiSw velocijifcausing deposition and sorting of
materials. The transport and d<
storm frequency and the
required to, en&ain and
The
lurces is a primary concern at
•b large areas of ground,
.verse impacts to aquatic
evaluate the
ity and aquatic life.
DBS permits. As
any given time in a stream
am flow velocity. As
a stream, therefore, dependent on
cases, high flow events are periodically
Deposited during low flow periods when
icse are known as channel maintenance flows.
; one that over tune, transport sediments with no net
, erosion.
(ElR) and Equal Width Increment (EWI) methods are
;ample suspended sediments during stream flow (USGS, 1960).
commonly used field
Usingthese methods, seveS||piter samples are taken along cross-sectional transects (i.e.,
perpendicular to flow direction). Samples along the cross section are taken by lowering a sample
botfle through the stream" at a rate dependent on the flow velocity. The total mass of suspended
sediment and its particle size distribution are measured for each sample. Automatic sediment
sampJeE| are also available that collect stream samples at scheduled times that are determined by
the user. These data are used to develop a sediment rating curve or a sedigraph that defines the
relationship between stream flow discharge (QJ and the mass of suspended sediment at a given
sampling station. After a sediment rating curve has been developed, stream flow measurements
can be used to estimate sediment discharge at a given station. Sediment rating curves and
sedigraphs can be extremely useful for monitoring the effectiveness of control practices applied
to minimize erosion and sediment yield from mine sites. The development of sediment rating
H-8
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Mining Source Book
Appendix H — Erosion and Sedimentation
curves, however, requires sampling across a large range of flows and at different seasons of the
year. These relationships can be continuously recalibrated and refined as the size of the sampled
data base increases.
Net increases in sediment deposition in streams and other water bodies ajSmeasured
using substrate core samples at various times of the year. Core sample^^keBJising a variety of
substrate and coring equipment, are analyzed for net changfj||a.partie|lS^^stribution over
time. It is important for water quality analyses at mines,
sedimentation in stream beds incorporate comparisons \%
sampling throughout the year is required to determine ijf
in a stream over time. Sediments are naturally deposit!
are naturally entrained and transported during high flo
analysis by sedimentation extremely difficult to monitor.
_ i monitor
stream flew
depojjpon of semtaentsis occurring
sasonal low flow periods and
icse processes make impact
In addition to the above analyses, characteriza|ym of morphology from
drainages potentially affected by a mining neces^^pfletermine potential
impacts caused by changes in flow regime TJjIse analyses may include
photo documentation of streams and
classifications of streams using the to define channel
cross sections, width to depth ratios^Kitudinalprofiles,^^Sity, and pool/riffle ratios. These
data would support studies condug»y0 charajjerize sitejpf drology and aquatic resources.
4.4 Software and Watershf
lodelsJ
>n of Sediment Yield
large wat
adverse imf
erosion and se<]
sediment
.ft$?L_
into G^^plications •
or mgjFwatersheds.
izationi
Tocl
require^Hteaccurate calculation of sediment yield on a
^baseline conditions at mine sites and to predict potential
is adequate spatial and areal characterization of gross
lyrical software programs are available to predict
ispowin large watersheds. Some of these can be incorporated
3atial evaluation of erosion potential and sediment yield for one
eif
The MUSLE anJpRUSLE, applications described in Section 4.2.1 could be used to
terize baselinejpiditions of sediment yield and to evaluate potential changes in expected
it yield result from development of mine facilities. Most software, watershed
Implications mat are commonly used to predict erosion and sediment yield apply
^ MUSLE, or RUSLE algorithms. A brief description of analytical software used
for watershed analysis and for the evaluation of sediment yield is provided in Section 4.4.2.
Particular emphasis is given to those methods that are commonly used in mine settings.
H-9
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Mining Source Book
Appendix H — Erosion and Sedimentation
The following questions, modified from Maclean (1997), can be used to determine the
type and level of modeling effort needed and software required to evaluate erosion and
sedimentation at mine sites:
What are the basic assumptions and method(s) applied in the model?|
Is the output suitable to make the evaluations and analyses requir
sufficient for characterization, impact analysis, and deten mo
What are the temporal and spatial scales of the
•* •&$ 3- -./
What are the input data requirements of the softwaregir model?
t"l 71 A J _i._ .«._«. «& *+. n. *3 « f\ -fUiv ••«yk*J/'-fcl s%nli irvvn+t s\-r\ r»*"^/-4 i r^v^S^f%n^-\f\.tr\f ^111
What data are needed for model calibration and
Are the required data available and are they at the
What input data are the most important (i.e., have thl
Can surrogates be used for missing data without cor
If the model uses empirical (i.e., statistical) relation
formed?
ition?
ips,
sitivity)?
i accurate analysis?
.conditions were those
Answering these questions will
techniques and models and to design adeqjj sampj
data. As previously discussed, to adequjply evaluj an£
require temporal and spatial analysis,^! large \gpershed.
sampling programs that will provig^.Jequatej^ta on a'
to evaluate erosion and sedimen|f|pm shouUft coorc
water quality^ characterization s^les. Th
Appendix ^Receiving l&^^m: related
Jpgist tqj^glect appropriate
ibtain the required input
mpacts at mine sites typically
necessitates the design of a
Fershed basis. Monitoring programs
;d with baseline hydrological and
to Appendix A, Hydrology and
4.4.1
A conci
parameters
I Site Model
:.|npdel ci^tw used to expedite an evaluation of the questions and
on 4.3. A conceptual site model is a depiction, descriptive, or
pictorial, of subwatershl|^^p|^pes, slopes, stream channels and any erosional features. Such
a model should be devete(p^MHbonj unction with studies to characterize baseline soil and
vegetation types and surjjbe^water bodies. The purpose of building or developing a conceptual
model of a site is to show important interrelationships that need to be evaluated, studied, or
modeled. Programs tosanalyze impacts and monitor site conditions can then be developed. The
conceptual modj1 should be complex enough to adequately depict system behavior and meet
study objectives, but sufficiently simple to allow timely and meaningful development of field
sampling programs and predictive models.
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Mining Source Book
Appendix H — Erosion and Sedimentation
4.4.2 Analytical Software and Models.
AGNPS - Agricultural Non-Point Source Pollution Model
f
AGNPS is a distributed river basin model which combines elements of several other
models to predict erosion, runoff, and sediment and chemical transporj," The model incorporates
the USLE to predict gross erosion from defined grids withia&he river basm. Runoff and
overland flow is calculated using Natural Resource
Conservation Service]) procedures (see Appendix A, Hyflogy). Trarsportlliid'jJeposition,:
relationships are used to determine sediment yields ancplute sediaiiht
basin. The program is designed for large basins and re|
data for input. The level of accuracy necessary for the j
at mine sites would require detailed field sampling to prc
inherent problems associated with the USLE, descrit
with the SCS hydrologic methods to predict runoff
assumptions of the USLE and the SCS methodsy
this model for predictive purposes. A revie\
detailed site characterization
f sediment yield and transport
ita. The model has the
and problems associated
•ology). The
•stood when using
iyJakubauskas(1992).
ANSWRS - Areal Non-Point Source WajjFshedR
ANSWRS is a distributed
model uses the USLE to predict j|ppland
equations to simulate sedimj
>n Model
ilar to the AGNPS model. The
gross erosion and a set of steady state
Sin. A review of this model is provided
S models are designed to evaluate
intense cultivation.
Hydrology Model
e soifphysical properties and meteorological and vegetation data
iporation, plant transpiration, unsaturated flow, and surface and
uses the Green and Ampt infiltration equation to estimate the
ss precipitation. Excess precipitation is routed downslope to
surface
drainage.
Id volume of sto
ate the overland hydrograph using the kinematic wave method. In WEPP, surface
'is used to rill erosion and runoff sediment transport capacity. The infiltration
is linkedJpn the evapotranspiration, drainage, and percolation components to maintain
%ater balance for a watershed.
HEC^Scour and Deposition Model
HEC-6 is designed to evaluate long-term river and reservoir sedimentation behavior. The
program simulates the transportation of sediment in a stream and can determine both the volume
H-ll
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Mining Source Book
Appendix H - Erosion and Sedimentation
and location of sediment deposits. It can analyze in-stream dredging operations, shallow
reservoirs, and scour and deposition effects in streams and rivers, in addition to the fall and rise
of movable bed material during several flow cycles. The program is primarily designed to
analyze sediment transport and geomorphologic effects in rivers and streams. It ist intended
for use in analyzing gross erosion or sediment yield from watersheds.
Sedimont-H - Hydrology and Sedimentology Model'
Sedimont-II is designed to generate and route hyjipgraphs anii
multiple subareas, reaches and reservoirs. It can also bejised to e^ltuate the
^^JT* ' ^.^f^'^^. ^•:'r'/^y
sediment detention ponds and grass filters. The progra^^^^pict peak sedim
concentration from a flow event, trap efficiency of a sed|M|^^fention basin, sediment load
discharge, peak effluent sediment concentration, and pe
SEDCAD+ 2
SEDCAD+ provides computer-aided,
evaluation of storm water, erosion, and sejfent
combines hydrological and sediment
evaluate the performance of sedimenUitention
dams, culverts and plunge pools.
volumes, areas, and cut/fill voluaf|sf The pj
calculate sediment yield from watersheds.
Surface Mjjpig's Technic^iofqrmation P^p^
programsjij?||ippde automatedsoftware tox
scientific applil:afii$Bs required for fefenitting.
* '* rislKi^fJ^k-fel TfcJ,. X ^:'a*«,,-A,'&?&x7&:"-^ fJ
PONDPACK
through
M
cable concentration.
iabiliti^PEbr the design and
practices. The software
•abilities to design and
uns, cnajptferC grass filters, porous rock check
prograrjjprovides determinations of land
usejfle MUSLE and RUSLE algorithms to
has used as a part of the Office of
Tystem (TIPS). TIPS is a series of integrated
irt a full range of engineering, hydrological, and
PONDPACK is di@^|4o provide CAD capabilities for the design and evaluation of
storm; water detention po^sJ^pie program provides analysis of detention storage requirements,
computes a volume rating taHe for pond configuration, routes hydrographs for different return
frequencies, and provides routing data for inflow and outflow hydrographs for comparing
alternative pond designs.
1 Haestead Methods, Waterbury, Connecticut.
2 Civil Software Design, Ames, Iowa
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Mining Source Book
Appendix H - Erosion and Sedimentation
4.4.3 Application of Remote Sensing and Geographical Information Systems (GIS).
Recent research has evaluated the use of Geographical Information Systems (GIS) and
data obtained from satellites in predictions of large-scale erosion potential. Example studies are
provided by MacLean (1997) and DeRoo et al. (1989); other references are provided at the end of
this appendix. In general, GIS systems can be used to provide spatial data for soil-types,
vegetation cover types, aspect, slope, slope-lengths, and other-variables that are required inputs
for large-scale watershed models. These data may bes incorporated or estifiai^using remotely*
sensed data obtained from SPOT or LANDSAT imagery.- Modeled data can alsVlt^iresente
and analyzed using a GIS system as demonstrated by the^studies ripirenced aboven
incorporated spatial data into large-scale, river basin models thai evaluated erosion potential and
prediction using the USLE. In general, these studies showed that a GIS system could be used to
manage, provide and evaluate large amounts of spatial data-in xxrajonction with erosion
modeling. These studies, however, indicated that model accuracy aad validation were deficient
because specific site data were not available or had to be assumed." DeRotfet al. (1989)
suggested that model accuracy is extremely sensMveJp Ihe "lack oflletialed" input data such as
infiltration capacities, antecedent soil moistur|f 1and"*aitfiall rntensityJSbrmation for specific
sites. MacLean (1997) indicated that confjilnce in
"spatial]
;§is of ii
info]
These studies indicate that 1;
for baseline characterization and
scientists must be aware that sp
vegetation types, slopes, slqre-lgigths, am
erosion Caui
with si
s v ed using GIS was low.
-•%, ' *tr
,-' if '
* S *
itegrated systems could be used at mine sites
;ts. Hojllver, mining hydrologists and other
in-regarjpfg soil-types, soil particle size analysis,
drology are required to produce accurate
e used when integrating spatial data bases
Rfific data are inadequate.
REPR]
)ATA
and statistical concepts related to sampling and the
lent of data are discussed in detail in Appendix A, Hydrology. In
I, the principles with sample adequacy, statistical techniques and the
fopment of Qualitjw[ssurance programs for erosion and sedimentation are similar to those
|ated with hydrjp!|ical measurements. A detailed discussion of these concepts is not
herein; is referred to Appendix A for a discussion of statistical techniques and
; to consider in developing adequate sampling designs. Several concepts
feasurement of erosion and sedimentation should be considered when developing
Data Qua% Objectives and sampling programs. The following points provide specific concepts
which should be applied or noted in developing programs for monitoring erosion and
sedimentation at mine sites:
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Mining Source Book
Appendix H — Erosion and Sedimentation
The processes of gross erosion, sediment yield, and sediment deposition in streams depends
on the frequency and probability of hydrologic events, both seasonally and on an event basis.
The amounts of sediment erosion, transport, and deposition vary seasonally and in response
to individual precipitation-runoff events of different frequencies. For this reason*
characterization and monitoring programs at mine sites must be designed to,«|Siluate erosion
and sediment yields with respect to the frequency of storm events, ^^glj^^ccount for both
seasonal and annual climatic variations. Similarly,
to evaluate suspended loads in streams must take into
measurements. Impact analysis can only be condm
developed between precipitation and runoff, stre
The effectiveness and accuracy with which mathe:
predict gross erosion, sediment yield, and sediment
specific data collected to characterize soils, vegetatic),
watershed or subwatershed parameters. Of speci
to determine the particle size distributions (i.e.,
statistically adequate population. Adequate
other surface roughness factors controlli
essential.
The use of spatial data and GIS anaypis shoi
potential impacts-on a watershedjhjjtis. The,
provide spatial analyses of arq
however, the accurate predi
having adequately charaei
unt strea;
ifadequai
iment lol
fels and empiricat eqjpttions
depends on the quality of site-
, slope-lengths, and other
the samples collected
provide a
characl^f^SSP^getative cover and
flow velocities is also
evaluate and predict
e used to develop maps and
discussed in Section 4.4.3,
itation on a large-scale depends on
6.0 METHODS 10 MIT
•SIGN AND SEDIMENTATION
are schedules of activities, prohibitions of practices,
. nranagement practices that effectively and economically
control prdolems wimaBafc^^ioiling the quality of the environment. Erosion and sedimentation
may be Effectively contrl^^^'employing a system of BMPs that target each stage of the
erosion process. FundaraenMly, the approach involves minimizing the potential sources of
secfiment from the outset In order to accomplish this, BMPs are designed to minimize the extent
and duration of land disturbance and to protect soil surfaces once they are exposed. BMPs are
also designed to control the amount and velocity of runoff and its ability to carry sediment by
diverting incoming flows and impeding internally generated flows. BMPs also include the use of
sediment-capturing devices to retain sediment on the project site. The types of BMPs discussed
in this appendix include surface stabilization procedures, runoff control procedures and
conveyance measures, outlet protection procedures, sediment traps and barriers, and stream
protection procedures. Table H-l provides an outline, by categorical type, that are used at mine
H-14
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Mining Source Book
Appendix H — Erosion and Sedimentation
sites. Sections 6.1.1 through 6.1.5 provide brief descriptions of these BMPs. Many of the BMPs
are complementary and are used together as part of an erosion control program.
An important BMP used at mine sites to capture, manage and control sedirnfptation is the
use of Sediment Detention Basins. Section 6.1.6 describes detention basins andjttseusses
important design parameters for these basins at mine sites.
Table H-l. Mining BMPs for Control of Erosion and Sedimenta
Best Managemen
Surface Stabilization
Dust control
Mulching
Riprap
Sodding
Surface r
Tempofj
Teraiiorarv am
rass-linefipchannel
ardergjphannel
PavedHlme (chu
Runoff Control and Conveyance Meas
Lev
Outlet stabilization structure
sh barrier
eck dam
Grade stabilization structure
Sediment basin/rock dam
Sediment trap
Temporary block and gravel drop inlet protection
Temporary fabric drop inlet protection
Temporary sod drop inlet protection
Vegetated filter strip
Sediment Trap
Check dam
Grade stabilization structure
Streambank stabilization
Temporary stream crossing
Source: NCSU Water Quality Group (1998).
H-15
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Mining Source Book
Appendix H — Erosion and Sedimentation
6.1 Best Management Practices (BMPs) Categories
The following discussion of Best Management Practices is adapted from NCSU Water
Quality Group (1998).
6.1.1 Surface Stabilization Measures.
Dust Control is the manipulation of construction argpi&rough
prevent soil loss as dust. Effective control measures inc.Bed toiiibtect andjlabilize areas which are prone to
areas where vegetation cannot be
is includes channel slopes and bottoms,
ns, streambanks and shorelines.
of exposed areas with rolls of grass to provide
especially useful in areas with a steep grade, where
ching, sodding fosters vegetation growth, minimizes
raindropiimpact energf||||peases surface roughness and reduces the velocity of runoff.
Temporary Gravel Construction Access is a graveled area or pad on which vehicles can
drop their mud and sediment. By providing such an area, erosion from surface runoff, transport
onto public roads, and dust accumulation may be avoided. This BMP is designed to capture
potentially exposeefesediment sources so they may be further managed and controlled.
Temporary and Permanent Seeding involves planting areas with rapid-growing annual
grasses, small grains, or legumes to provide stability to disturbed areas. Areas are temporarily
seeded if the soils are not to be brought to final grade for more than approximately one month.
Permanent seeding is established on areas which will be covered with vegetative growth for more
than two years. This BMP establishes a relatively quick growing vegetative cover.
H-16
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Mining Source Book
Appendix H — Erosion and Sedimentation
Topsoiling is the application of loose, rich, biologically active soil to areas with mildly
graded slopes. Often, facilities will stockpile topsoil for future site use. To ensure that runoff
contamination does not occur, sediment barriers and temporary seeding should be used.
6.1.2 Runoff Control and Conveyance Measures.
A Grass-Lined Channel is a dry conduit vegetated
conduct storm water runoff. In order for this system to
established and rooted before flows are introduced. Linif
flows are to exceed 2 cubic feet per second (cfs). A
the channel, reduces flow velocities and promotes the <
The channel itself is also protected from erosion of the
properJ^p^g^ss must be w- <
"of the cha^liillsieftdted if design
IchanneiiStreases shear stress wi.tfain
sediments ii
les.
Hardened Channels are conduits or ditches ImaiPwitE
^Ir
or paving. These channels are designed for the conveyance,
storm water. These channels are often used in
potential for traffic damage, erodible soils, o:
Ru
runoff
The type!
or berms thai
intercept, coll
of spoil
PermanjjjpPQiversions;
flowsJpEexpected, are
Drary o:
: it carf
aterials such as riprap
safe disposal of excess
igjjjj^gj^ x
jpes, prolonged flow,
Paved Flumes are concrete-linedWnduits tip ground. Flumes are used to
convey water down a relatively steep^&jfpe withspT This system should have an
additional energy dissipation featu^^y-educe^psion orJPWing at the outlet. Flumes also
should be designed with an tha^ptes extrjpl flows away from the flume.
structures which channel, divert or capture
8 or released without erosion or flood damage.
)se include graded surfaces to redirect sheet flow, dikes
. protected area, and storm water conveyances which
iporary diversion may be constructed by placing dikes
ithe dllffn-gradient end of an excavated channel or swale.
puilt to divide specific drainage areas when a larger runoff
Sapture and carry a specific magnitude of design storm.
Temporary Slam/Drains are temporary structures constructed of flexible tubing or
jit which convejptnoff from the top to the bottom of a cut or fill slope. In conjunction with
3ns, these are used to convey concentrated runoff away from a cut or fill slope until
sures, such as stabilization with vegetation, can be established.
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Mining Source Book
Appendix H — Erosion and Sedimentation
6.1.3 Outlet Protection.
Level Spreaders are a type of outlet designed to convert concentrated runoff to sheet flow
and disperse it uniformly across a slope. The landscape of the receiving area must be uniformly
sloped, the outlet lip leveled, and the land unsusceptible to erosion. To avoid rngformation of a
gully, hardened structures, stiff grass hedges, or erosion-resistant matting|^houp be incorporated
into the design. This type of outlet is often used for runoff d||ersior
Outlet Stabilization Structures are outlets that rej
flow energy. These types of structures are used at the
discharge velocity exceeds that of the receiving area.
aprons, riprap stilling basins, or plunge pools.
6.1.4 Sediment Traps and Barriers.
Brush Barriers are temporary sediment
or at the toe of a slope susceptible to interill
vines, root mats, rock, or other cleared
let of a channel or c
s> »-•
immon
Check Dams are temporary,
drainageways other than live stre
channel erosion. In their pei
they are completely filled. At thgppoint, a,
gradient oveciwhich the vpBic^ades to
f,~. • ••'.. '• '-. jii^:.;.•.•.-..''•^ijMS^bss;*
alternatives
Oi?- **-:.,.>;•,;,> x. _^ x,»;.
on a tempctaa^piasis. Dams
head
design;
'-lined
:o form a berm across
insist of limbs, weeds,
'gency, «perman^psfructures constructed across
tere tharare usedji restrict flow velocity and reduce
iplicajjjjl' these gradually accumulate sediment until
br delta is formed into a non-eroding
gh a spillway into a hardened apron. Other
be evaluated before selecting the check dam
be porous or nonporous. Porous dams will decrease the
of the flow through the actual structure.
,.-%x,
GradeStab
constructed Channels to
designed to reduce channel grade in natural or
fxosion of a channel caused by increased slope or high flow
velocities. This type ofstofeelncludes vertical-drop structures, concrete or riprap chutes,
gabions, or pipe-drop structures. In areas where there are large water flows, concrete chutes or
vertical-drop weirs constructed of reinforced concrete or sheet piling with concrete aprons are
recommended. For areas with small flows, prefabricated metal-drop spillways or pipe overfall
structures should be used.
v; Sediment Detention Basins can be either permanent pool or self dewatering (i.e., complete
flow through) types. They are primarily designed to allow ponding of runoff or flows so eroded
soils and sediments can settle out and be captured before they can enter streams or other water
bodies. The design and use of these basins is perhaps the most important BMP applied to control
H-18
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Mining Source Book
Appendix H — Erosion and Sedimentation
erosion at mine sites. Section 6.2 provides a detailed discussion of important design and
management considerations for Sediment Detention Basins.
Sediment Fence (Silt Fence)/Straw Bale Barriers are temporary measures used to control
sediment loss by reducing the velocity of sheet flows. They consist officer fabii
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Mining Source Book
Appendix H — Erosion and Sedimentation
6.1.5 Stream Protection.
Check dams, grade stabilization structures, and streambank stabilization techniques are
also BMPs used for stream protection. An additional stream protection BMP is a Temporary
Stream Crossing. These crossings may be in the form of a bridge, ford,
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Mining Source Book
Appendix H — Erosion and Sedimentation
design storm basis. Vd is the storage volume that is required to detain and hold the volume of
runoff from a specified design storm long enough to allow the sediment to settle out. A variety
of methods are used to calculate storm runoff volume (Vf) (see Appendix A, Hydrology). Vf is
the final flood storage volume or free board which is added as contingency to prevent
overtopping and dam failure during extreme events that exceed the desigg capacjg|r
to minimize
as the ratic
SSowiogoutofai
•.?X I .A ^*^ ..&K...-*a. j&y r
efficiency of a basin:
• Particle size distribution of sediments
• Detention storage time
• Reservoir shape, amount of dead storage, and turbj
• Water chemistry
• The use of flocculants
Because sediment detention basijlFare usi
^ma?
are optimized by setting design criteriajji goals
for a given design storm (i.e., stor
sediment detention basins based
standard is based on the criteria
structures, trap efficiencies
important
related to sc
or aggregate si
reason, acci
is critical!® pond
tmax
fAt mine
24-ho
r
capture of all settleable solids
es, it is common practice to design
ipitation event. This design
of excess storm water at mine sites.
; into a detention basin is the single most
|cy (Barfield et al., 1981), because particle size is directly
idy-state flow through a reservoir, a decrease in particle
ffw length to allow a particle to settle out. For this
offflfiicle size distributions of potentially incoming sediments
agement.
' The detention st*gWime is the volume-weighted average time that a volume of flow
: detained in a resffvoir. The detention time of a settling basin is a function of basin shape,
Uength and the of the outlet structure. The design of the outflow structure
ics the chaiilfteristics of the outflow hydrograph and its relationships to the inflow
shape strongly influences how effectively the storage volume of the basin is used
for sedimentation. The basin shape determines flow path length, flow velocity, areas of
turbulence within the basin, and if dead storage areas occur. Small localized zones of turbulence
within the basin can inhibit particle settling because of locally increased flow velocities. Dead
H-21
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Mining Source Book
Appendix H - Erosion and Sedimentation
storage areas are zones within the basin that are bypassed and, therefore, ineffective in the
settling process. EPA (1976) suggests that dead storage volume can be minimized by
maintaining a 2:1 ratio between reservoir length (i.e., the length of the flow path) and reservoir
width.
, the ionic
ion. Flocculation
trength. Thejpr
calcii
Water chemistry also affects particle settling and trap efficiency!
strength of the water is a primary factor affecting particle floeculationj
of particles to larger, heavier aggregates generally increases with men
types of cations present, however, also affect this process^ Because
and magnesium cations tend to be very effective in increasing flocgplation.
strength on flocculation and dispersion can be specifica^wetofl, uierefore, to
concentrations of these cations in solution. The Exchan^^^^sdium Percentage TflSSP) and the
Sodium Absorption Ration (SAR) are useful parameters^p^^mbe examined when
evaluating the effects of water chemistry (Barfield et
Flocculant, which are compounds that
to aid the performance of a detention basin
standards are met at the basin outlet. Flocjlphts ere
velocities. They can be particularly uselpvhen
clay, fine silt, or colloidal materials. (Jfiloidal jrticles:
out even under quiescent conditions? BarfieldjjFal. (1981
water chemistry, flocculation and^e'design^fprogra
sediment detention basins.
kaggregat
5, to ens!
tides, often are used
at water quality
Is that have greater settling
i>f entrained sediment are
m suspension and will not settle
provides a detailed discussion on
: enhance settling using flocculants in
particular's
specifically
f: ;
detention basinsSii
basins to opts
iployed to design sediment detention basins. In
id SEDIMONTII, described in Section 4.3.2, are
kand erosion measurements to the design of sediment
rare, a hydrologist can iteratively design detention
, detention storage time, and the type of outflow structure
required to "meet desigri||StfiS^|These models provide analyses of both inflow and outflow
hydrographs and inflow^a^^Bbw sedigraphs. Analyses are performed to provide estimates of
trarjfefficiency, mass of JjpttJreible solids captured, and mass of suspended solids not retained by
theibasin. Basins desigrkd using software packages depend on accurate input data for hydrologic
and soil variables, ^particular, accurate information regarding soil types and particle size
distributions (texture) are necessary for accurate design.
„. >.*;;«.
'" - "* •..•::*.
.'•:&•-
6.2 Innovative Control Practices
Most erosion and sediment control BMPs have been standard practice for many years. As
discussed in Section 6.1, standard BMPs include surface stabilization measures, diversions and
H-22
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Mining Source Book
Appendix H — Erosion and Sedimentation
channels, and sediment traps and barriers. Some innovative BMPs, however, include variations
of these practices that offer particularly effective controls. These practices include:
• The design and construction of artificial wetlands to provide natural filtration aa4 enable
sediment deposition. Artificial or constructed wetlands can effectively removesuspended
solids, particulates and metals attached to sediments through the physical processes of
velocity reduction, filtration by vegetation, and chemica|^ecipitaticai aswater flows through
the wetlands.
''
The use of geotextiles for soil stabilization and erosJjP'control blanketeandmattings.
«. • * * -. *. _ _ . j^liw^' s*. **
Geotextiles can be made of natural or synthetic mai
permanently stabilize soil. Synthetic geotextiles an
materials and are generally classified as either Turf
Control and Revegetation Mats (ECRMs). TRMs
monofilaments formed into a mat to protect seeds
composed of continuous monofilaments bound b
They serve as a permanent mulch.
Biotechnical stabilization techniques that
Biotechnical stabilization can control qdprevent
Jjjjj<*° ;
This technique involves the use of cwBranchesmd
and poplar. The live brush is mt
-------
Mining Source Book
Appendix H — Erosion and Sedimentation
basis, as well as on a seasonal or annual basis. Developing monitoring programs that accurately
detect or evaluate impacts and control effectiveness depends on having accurate knowledge of
natural erosion and degradation rates and patterns.
The choice of methods to predict gross erosion and sediment vie!
disturbed areas may be dependent on the type of input data required. I;
mining hydrologist understands all assumptions inherent injpsnodel
analyses to predict sediment yields or design erosion contpp^ccural
software programs and models requires accurate site-spfffBc sampli:
Vegetation parameters, soil types, and soil particle size
important parameters that are input to predictive modelf^t^^^pr programs.
8.0 CITED REFERENCES
Barfield, B.J., Warner, R.C., and Haan, C.T., 19
Disturbed Lands, Oklahoma Techni
DeRoo, A.P.J., Hazelhoff, L., and Burn
and Geographical Informatio
pp. 517-532.
Foster, G., 1985. Processes of Sjfp Erosio:
Erosion and Cropji^fivity, A
•alor
portant that the
conducting
,by available
:*K »
Sedimentology for
pp.
isK"1
bn Modeling Using Answers
vcesses and Landforms, vol. 14,
r. Follett, R. and Stewart, B., eds., Soil
Siety of Agronomy, Inc., pp. 137-162.
sky, T.A., 1986. Erosion & Sediment Control
mpany, New York, W87-08686.
• anillM.E. Dillworth, 1992. Classifying Remotely Sensed Data
for Use in an A§iiH&,Nonpoint-Source Pollution Model, Journal of Soil and Water
' ' '• \Z? *#.^a>/fe .gap*^*?^1 '
-------
Mining Source Book
Appendix H - Erosion and Sedimentation
McCool, D.K., L.c. brown, G.R. Foster, c.K. Mutchler, and L.D. Meyer, 1987. Revised Slope
Steepness factor for the Universal Soil Loss Equation. ASAE Transaction 30(5).
Musgrave, G.W., 1947. Quantitative Evaluation of Factors in Water Erosion, A Fiigt
Approximation, Journal of Soil and Water Conservation, vol. 2, no. 3, ppJt33-138.
NCSU Water Quality Group, 1998. Watersheds: Mining and/AcidMjji
Carolina State University, Department of BiologicJpnd Agric
Raleigh North Carolina.
Rosgen, D.L, 1994. A Classification of Natural Rivers:
^
U.S. Environmental Protection Agency, 1976. Effectivei
Ponds, U.S. Environmental Protection Agencyftoi
B.C.
U.S. Geological Survey, 1960. Manual of H;
Geological Survey, Reston, VA.
I 22, pp.1
Mine Sedimentation
g-87-117, Washington,
l|i,
iply Pater W1541. U.S.
Williams, J.R., 1975. Sediment YieldJ^dictionMth Uni^jjUrEquation Using Runoff Energy
Factor, U.S. Department oj4^cultuq0teport U^A-ADS S-40, Washington, D.C.
'"*
Wischmeier, W.H. and Smith, Losses from Cropland East of the
Agriculture Handbook No. 282,
8.1 Add
Barfield, R.G., 1979. Sediment Yield in Surface Mined
; Symposium on Surface Mine Hydrology, Sedimentology and
if Kentucky, Lexington, Kentucky, December 1979, pp. 83-92.
BjBild, B.J. and Moojifl.D., 1980. Modeling Erosion on Long Steep Slopes, Office of Water
I Resources Tejpiology, Project No. R4052.
f Trap Efficiency of Reservoirs, Transactions American Geophysical Union,
fno.3, pp. 407-418.
Chen, C., 1975. Design of Sediment Retention Basins, Proceedings: National Symposium on
Urban Hydrology and Sediment Control, UK BU 109, College of Engineering, University
of Kentucky, Lexington, Kentucky.
H-25
-------
Mining Source Book
Appendix H — Erosion and Sedimentation
McCool,
^apd Brooi
iwest,
Curtis, D.C. and McCuen, R.H., 1977. Design Efficiency of Storm Water Detention Basins,
Proceedings: American Society of Civil Engineers, vol. 103 (WR1), pp. 125-141.
Curtis, W.R., 1971. Strip Mining, Erosion, and Sedimentation, Transactions: American Society
of Agricultural Engineers, vol. 14, no. 3, pp. 434-436. *
,v ,y
Fogel, M.M., Hekman, L.H., and Ducstein, L., 1977. A Stocl^stic Sedimeot Yield Model using
the Modified Universal Soil Loss Equation. In: S^^bsion. Prediction and Control,
Soil Conservation Society of America, Ankeny, 'N" >", * k
Graf, W.H., 1971. Hydraulics of Sediment Transport,
Hill, R.D., 1976. Sedimentation Ponds - A Critical
Coal Mine Drainage Research, Louisville, Ke:
Kao, T.Y., 1975. Hydraulic Design of Storm Wj
Symposium on Urban Hydrology
Engineering, University of KentucJ^pLexm
Lantieri, D., Dallemand, J.F., Biscaia, 1$?,
,'^./"X^'.V
Using High-Resolution Satellite^ Data
Brazil, RSC Series No. 56, FAX), R
111, New York.
j1
TS: Sixth Symposium on
feedings: National
09, College of
.O., 1996. Erosion Mapping
Information System, Pilot Study in
pp.
" ^^
6. The Universal Soil Loss Equation as
: 3rd Federal Inter-Agency Sedimentation
ouncil, Washington, D.C.
Miller, C.R., 195|
Co-
Morgan, R., 1986. S0//1
Weight of Sediment for Use in Sediment Volume
^zjjjjr&z^jtii?
iu o^Keclamation, Denver, Colorado.
i>
'nd Conservation, Longman Scientific and Technical.
Neibling, W.H. and Foster, G.R., 1977. Estimating Deposition and Sediment Yield from
,. Overland FlowlProcesses, Proceedings: 1977 International Symposium on Urban
^^JJydrology^Hydraulics and Sediment Control, UK BU 114, College of Engineering,
University of Kentucky, Lexington, Kentucky.
Risse, L.M., Hearing, M.A., Nics, A.D., and Laflen, J.M., 1993. Error Assessment in the
Universal Soil Loss Equation, Soil Science Society of America Journal, vol. 57, pp. 825-
833.
H-26
-------
Mining Source Book
Appendix H — Erosion and Sedimentatic
U.S. Environmental Protection Agency, 1976. Erosion and Sediment Control-Surface Mining
the Eastern U.S., Vol. I and II, U.S. Environmental Protection Agency Report EPA-
615/2-76-006, Washington, D.C.
<(!||£S;j^-
Ward, A.D., Barfield, BJ. and Tapp, J.S., 1979a. Sizing Reservoirs for SedimejjtControl from
Surface Mined Lands, Proceedings: 1979 Symposium on Surfa&JMjnejiiydrology,
Sedimentology and Reclamation, College of Engineering, Uni'f^i^Sf Kentucky,
T . . Tj- , i 4feaSl6' ^inBX-ifiJESfeV
Lexington, Kentucky.
in
--.•.-^~-'^ -y ••;--'-;-~%;; s^s*/'-.-• *
Ward, A.D., Haan, C.T., and Barfield, B.J., 1979b. PreMtion of .Sediment B^^3|eribmiance,
Transactions American Society of Agricultural iSliipee/lpvol. 22, no. 1^68.121-136.
•^ ** tJ »^gg^«3^^feiKffeie:s;.''>' 7 y i. JT
Ward, A.D., Haan, C.T., and Barfield, B.J., 1980. The
American Society of Agricultural Engineers, vo
liment Basins, Transactions
1-356.
Williams, J.R., 1976. Sediment Yield Prediction wt&jfjversal Runoff Energy
Factor. In: Present and Prospective Yields and
Sources, U.S. Department of Agricj^are, Publication
ARS-S-40, Washington, D.C.
Williams, J.R., 1977- Sediment Dj||e1y Rati^Determin® with Sediment and Runoff Models,
Erosion and Solid Matte^^mnsport^nland Vjjj&r Symposium Proceedings lAHS-No.
122, pp. 168-179. .. If
Willis
Williams, J.R.
Proc.
WilsojfB.N., Barfield,
Hydrology and
Symposium on
AD-7
yGrraph MWIfBased on an Instantaneous Sediment Graph,
L 14, no. 4, pp. 659-664.
Yield Computed with Universal Equation,
i 98(HY12), pp. 2087-2098.
ier, R.C., and Moore, I.D., 1981. SEDIMOTII: A Design
itology Model for Surface Mine Lands, Proceedings: 1981
race
Mine Hydrology, Sedimentology, and Reclamation, College of
Engineeringjypiversity of Kentucky, Lexington, Kentucky.
t; 1959. A Rainfall Erosion Index for a Universal Soil Loss Equation, Soil
of American Proceedings, vol. 23, pp. 246-249.
H-27
-------
-------
Mining Source Bonk
Appendix I- Wetlands
Table of Contents
Section
3.0
4.0
5.(
1.0 PURPOSE AND GOALS OF THE APPENDIX 1-1
2.0 TERMINOLOGY AND ISSUES .A 1-1
2.1 Terminology ijjk. 4f . 1-1
2,2 Issues '..'.'.'.'.'.'.,-'.'.'.'.'. 1-3
2.2.1 Wetland Boundaries 1-3
i'J,--:' '^.,y"' " "'• sJis^-'-XwI. " " '
2.2.2 Local, State, and Federal Regulatoryjpmsideratipjis^
2.2.3 404(b)(l) Guidelines .§\ ^...
2.2.4 Mitigation '.... . .^
AFFECTED ENVIRONMENT
3.1 Introduction
Wetland Inventory and Mapping
Wetland Determination and Delineat
3.3.1 Delineation Criteria ..
3.3.1.1 Hydrophytic
3.2
3.3
3.3.2
3.3.1.3 Wetland,|fdrolo
Delineation Mj^ilms
3.3.2.1 Ro
3.3.2.2 C
3.3.1.2 Hydric Soi|ff 1-7
.............................. 1-10
..... : ........................ i-n
.............................. 1-11
.............................. 1-12
WetlI|pJvaluation Technique (WET) .................. 1-12
drogeomorphic Method (HGM) ..................... 1-13
1PACT AND COMPENSATORY MITIGATION ............. 1-13
4.1 Impact Asjjpsment ............................................... 1-13
4.1 .1 and Indirect Impacts ................................... 1-13
4.1 .2 .^mulative Impacts ........................................ 1-15
Insatory Mitigation .......................................... 1-16
1-17
6.0 CONTACTS AND OTHER INFORMATION SOURCES 1-19
I-i
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Mining Source Book
Appendix I - Wetlands
Table of Contents
(Continued)
List of Figures
Figure 1-1 Routine wetland determination for areas 5 acres or less and with relatively
homogeneous vegetation, soils, and hydrology .*^v . .J^K 1-9
Figure 1-2 Routine wetland determination for assessment areas greaterj||aa^ acres
and/or with complex vegetation, soils, and hto . feUi I-10
ListofTabl
Table 1-1 Example of Direct Impacts Table for Wetlan
1-15
i-ii
-------
specific
Environmem
observer, the
warrant
regulaj||FdeiInition o:
while all wetl,
to Jllisdictional wetlan<
1.0 PURPOSE AND GOALS OF THE APPENDIX
Wetlands constitute an important resource, in terms of impact assessment. Any project or
activity with the potential to impact wetlands should fully characterize this resource as part of
establishing baseline conditions and consider potential permit requirements in project planning.
Accurately describing existing wetland conditions at a site and identifying sources of potential
impacts should facilitate the development of alternatives and mitigation, includingiavoidance,
minimization, and as necessary, compensation,
TU ,. • 4
ine purpose of this appendix is to provide guidance^! determiE^pffeneeds, identifying
data gaps, collecting necessary baseline information and xpiducting an:l^cta|a]^sis for ,|t
wetland resources. The subsequent sections discuss we;$|nd termmql^y affiissfies;: *^
characterization of the affected environment; and impa^BpalysisilR list of ref^ni^ materials
and contacts are provided in the final section. This not address in dlttt,ime Clean
Water Act Section 404 permitting process, a topic discus^^fififexmain body of the source
- ;,;V.lii££.'i*l"V:-Jr>J'-\ J
document.
2.0 TERMINOLOGY AND ISSUES
2.1 Terminology
Terminology surrounding w<
wide variety of disciplines (e.g
involved as well as the fact
connotations^ The list of d
in the wetMlSiscience c
ider j
s often Jpnfusing. Ambiguity results from the
wildlifipbiology, soil science, and hydrology)
:n has both regulatory and ecological
9 on terminology that is generally accepted
Tthat wetland, is a general term that applies to
; wirninTfJTlandscape; while jurisdictional wetland applies to
the U.S. Army Corps of Engineers (COE), U.S.
id some state and local governments. To the untrained
atures, such as standing water or aquatic vegetation, might
wetland; however, these areas may or may not meet the
Mial wetlands as defined below. All jurisdictional wetlands are
Sot jurisdictional. All discussions of wetlands in this Appendix refer
"other Waters of the United States.
^JurisdictionaLjjitlands are wetlands that occur within jurisdiction of the COE and EPA
under 404 of the Clean Water Act. Under normal circumstances, wetlands
ria: hydrophytic vegetation; hydric soils; and wetland hydrology that must be
>rdance with the COE 1987 Wetlands Delineation Manual (1987 Manual).
Plants that grow in undrained hydric soils are referred to as hydrophytes or hydrophytic
vegetation. These plants tolerate varying degrees of soil saturation or inundation and some
species even continue to grow partially submerged. Undrained hydric soils are oxygen depleted
soils, a condition attributable to the prolonged presence of water in the soil. Wetland hydrology is
found where water saturates or inundates soils for an extended period during the plant growing
1-1
-------
Mining Source Book
Appendix 1- Wetlands
season. "Atypical" or "problem" areas may still be classified as jurisdictional wetlands despite
the absence of one or more of the aforementioned criteria.
A professional wetland scientist can be retained to make wetland determinations and to
conduct wetland delineations as per the 1987 Manual. Wetland determinations only denote
whether or not the land being assessed is a wetland. A wetland delineation defines the physical
boundary of a wetland once it has been determined that one exists on the property. It should be
noted that only the COE and EPA have regulatory authority to make jurisdictional^
determinations.
. .<*_
Waters of the United States is a regulatory phase mat defines th
COE under the Clean Water Act. The term generally appliesjte'navigabt*
that possess a 'bed and bank,' including those that may be intermittent or ep
wetlands are considered a type of Waters of the Unitedlitates anjPthe
wetlands as ".. .those areas that are inundated or saturatedle or ground
jurisdiction for the
1 and watercourses
irisdie^nal
and duration sufficient to support, and that under normal
vegetation typically adapted for life in saturated soil
a question exists as to the designation of a Water of ther|!
should be contacted for their interpretation.
Wetland functions. Wetlands may pro vide ha
|nces do support, a prevalence of
Section 328.3). Where
local COE district office
'"si
well as numerous other plant, wildlife, and-fish specj
in addition to providing habitat, including: shorelij;
filtration of sediments, nutrients, and, toxic cher
discharge areas for ground water. Besfeictioni§f wetlandsfipecifically can result in higher
downstream water treatment cost^iM the pjs^htial for jjpperty damage from increased flooding.
r endangered species as
perform other functions,
orage of flood waters; and
, and serving as recharge and
Wetland Values. Although often usei^^ipanction with "function," wetland "value'
refers to wetlandfattributes,d^^mined to bfc^yjluable to society. Examples of wetland values
include education,;"iecreatidliPp^Gs, tribal harvest areas, scientific study, contribution to the
V . :• •, . &. Nhsa«. i.':'s3®sft!^ilP!S*> •
economy and other social/cul
Navigable waters of the United-States are those waters that are subject to the ebb and flow
of the tide'and/or are presently used, or have been used in the past, or may be susceptible for use
to transport interstate of foreign commerce (33 CFR § 328.3). A determination of navigability,
oncemade, applies laterally over the entire surface of the waterbody, and is not extinguished by
later actions or events which impede or destroy navigable capacity (33 CFR § 328.3).
The USFWS's National Wetland Inventory (NWI) is a federal classification system for the
nation's wetlands and deepwater habitats (USFWS, 1998). USFWS publishes NWI maps for
many areas of the country. NWI maps identify wetland and deepwater habitat and are often
superimposed on U.S. Geological Survey (USGS) maps of various scales. USFWS produces
these maps through interpretation of remote sensing data (i.e., aerial photography) and limited
field investigations. NWI maps occasionally miss certain types of wetlands (e.g., forested
wetlands) and in other cases these maps include water bodies (e.g., wastewater treatment
lagoons) not under COE jurisdiction (Rolband, 1995; Stolt and Baker, 1995). Therefore, NWI
1-2
-------
Mining Source Book
Appendix I- Wetlands
maps should not be used as the only source of information to determine if an area contains
wetlands.
Riparian is a term that refers to "plant communities contiguous to and affected by surface
and subsurface hydrologic features of perennial or intermittent lotic and lentic water bodies
(rivers, streams, lakes, or drainage ways). Riparian areas have one or both of the following
characteristics: 1) distinctly different vegetative species than adjacent areas, and 2) species
similar to adjacent areas but exhibiting more vigorous or robust growth forms. Riparian areas are
usually transitional between wetland and upland" (USFWS, 1997). Riparian areas also often
include wetlands.
2.2 Issues
There are a number of issues that should be kept|&nind whin
of wetlands. Four issues presented in this appendix
wetland boundaries may vary over time; (2) local,
404(b)(l) Guidelines; and (4) compensatory mitigation.
2.2.1 Wetland Boundaries.
Wetlands often occur as transitional
soils persist over a relatively long period jiiC there
wetland even after it has been successful^ drain
significantly over both the short- (sejsipairy)
one must rely on a "normal year"^^-4o yei
(i.e., tree, shrub, or forb), may not
respond relatively quickly in
the a site seas<
delineate at
relevant to mme projects: (1)
J regulatory considerations; (3)
'',m
2.2.2
ydr
ong-te
eriod)
t lone!;
uatic habitats. Hydric
an area may still be a
the other hand, may vary
annually or longer), which is why
e. Vegetation, depending on form
conditions at the site because plants
y mapping effort should, ideally, consider
ferably multiple years rather than relying
ar instanfln time. Also, the easiest and most reliable time to
ie wettest period of the growing season.
tons
afforded juri
; federal enviro:
lents may reqi
ames place
•buffi
nal
tory Considerations.
ids, and the benefits they provide, is reflected in the potential
al wetlands established under the Clean Water Act and cross-
statutes. Beyond federal requirements, some state and local
permits for projects that may impact aquatic habitat and/or wetlands; or
restrictions on projects that could impact wetland habitat (e.g.,
ies around wetlands and other Waters of the United States). Therefore,
been identified in a project area, early consultation with state, federal, local
!es and resource agencies can help to clarify all issues and concerns.
^ ^^ _ _ - * f*r*
Communications with interested agencies will help to focus data collection efforts and may
improve the options for avoiding impacts through project design and mitigation.
2.2J 404(b)(l) Guidelines.
1-3
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Mining Source Book
Appendix I- Wetlands
The regulatory requirements of permitting under Section 404 of the Clean Water Act are
presented in the body of the source document. However, a brief acknowledgment of the
404(b)(l) Guidelines (Guidelines) may shed additional light on the subject of permitting and
environmental impact analysis. Prior to issuance of a permit by the COE for unavoidable
impacts to wetlands and other Waters of the United States, the Guidelines require the proponent
to demonstrate that the selected project alternative is the least environmentally damaging
practicable alternative. Often, the preferred alternative selected from the environmental impact
analysis of the National Environmental Policy Act (NEPA) process, is not the leas|it-
environmentally damaging practicable alternative because NEPA does not. haveffiie same
requirement as the Guidelines. It is therefore important to aypid and/ofii|^tfize all impacts to
wetlands to the fullest extent possible.
2.2.4 Mitigation.
A Memorandum of Agreement (MO A), dated F<
Environmental Protection Agency establishes the poli
and level of mitigation necessary to comply with Sectio
'no net loss' of wetland functions and values as a nati
mitigation, for practical purposes as minimization
mitigation is often the focus of project propom
minimization should be the focus of any
Waters of the United States. Due to theirjinportan'
M-£/ ^
here as they apply to the early stages ofijjroject p
will be discussed in Section 4.1 alongHfith othe§aspects q:
Avoidance addresses the ffpion of
issued if there is a practical
adverse impact to the aqu^fc
between thl||iEyand the
.ure in determining the type
idelines. The MOA sets
the types of
Wgh compensatory
iective, avoidance and
iact wetlands and other
minimization are discussed
Compensatory mitigation
pact assessment.
MOA addresses the reqi
guidelin|s%hich states that no permit shall be
itive t&artttpifj^e^ discharge which would have less
'gK 'l$..'vt':f','-^%*';* '*'>„•"^/ty'/' ^*^
stem iii^M|i|«Vetlands. The minimization aspect of the
I all appropriate and practicable steps taken which minimize
;harge. Avoidance and minimization would typically be
design through such things as alternative siting of
footprint of facilities that encroach on wetlands; and
the potential^advta^impact:
implemented during5e&ly phasel|
roads and infrasfecttir^%inimizi]
reducing or eKminating^Jaanipunt of fill for stream and wetland crossings (e.g. using bridges
instead of culverts where:
A project description.submitted as part of an environmental impact assessment or permit
application should cleaiiy demonstrate how avoidance and minimization have been addressed.
Realize that avoidance and minimization are part of an iterative process that will begin at the
earliest conceptual stages and continue through final designs. A pre-application meeting with the
COE may facilitate the permit process by identifying less damaging alternatives. Optimizing
avoidance and minimization may also be achieved by working with the COE, EPA and any other
interested agencies once the basic design criteria have been developed. Failure to consider
compliance with the Guidelines may result in project delays later in the permitting process or
outright permit denial.
1-4
-------
Mining Source Book
Appendix I - Wetlands
3.0 AFFECTED ENVIRONMENT
3.1 Introduction
Descriptions of the affected environment, as required in National Environmental Policy
Act (NEPA) documentation, may require: (1) an initial inventory and classification; (2) a
jurisdictional delineation; and (3) a functional assessment of wetland resources within the project
area. Prior to any assessment of the wetland resource, however, the affected environment to be
described must be established. Defining the affected environment andjassesspig wetland
resources within this environment are discussed below.
The first step in describing the affected environmjll is to establish me^stadysaEea or region
of influence (ROI) in terms of the proposed action and fential jj/jpect and indrrfc^feis to
wetland resources. For wetlands, the ROI typically extl|t|e^nd the footprintlsii^pfoposed
ground disturbance. A larger ROI ensures that potentiaf^|^|§ects to wetland hydrology,
water quality, and other functions are considered, mcludj^]^^^|gffects to down-gradient
areas that may occur as a result of the wetland impacts!!
Thi
*
delinearfS
environmel
jnder of,
ictio
Once the ROI is established, an initial and other
Waters of the United States is typically g^rlral nature and extent of
these resources within the ROI and to through
project design. Following refinement a within the ROI is
conducted to provide a comparison jflte effecjpf each ajprnative. A functional assessment of
wetlands is also conducted to cojliarison oiiffects between alternatives and
between pre- and post-project cojBftions.
taal information on inventory, classification,
it of weHlnds and how they relate to describing the affected
3.2 Wetlai
to the of ROIs and the numerous and conceptual nature of project
altenfTves early stage process, the initial inventory and classification of wetlands
is performed existing information (e.g., NWI maps, aerial photography, local
ir regional soil sujlys). NWI maps are an effective starting point for inventorying and
' ing potentiajjllands. Aerial photography and satellite imagery (collectively referred to
sensiailfoducts) are interpretive tools, often used in conjunction with NWI maps, for
of wetlands in the field. Remote sensing products can be obtained from a
^^.
sources including US Forest Service, USGS, COE, USDA Farm Services
Agency, USD A Natural Resource Conservation Service, state departments of transportation or
natural resources, and private contractors.
Depending on the season and type of remote sensing products available, wetlands are often
best identified using color infrared (CIR) aerial photography. However, wetlands can also be
1-5
-------
Mining Source Book
Appendix I - Wetlands
identified using panchromatic photography. When using remote sensing images it is helpful to
obtain coverage for the same area over a period of years and seasons as the vegetation boundaries
of wetlands may vary due to seasonal hydrologic changes. Where the use of a stereoscope is
possible, photography should be ordered as stereo pairs in the largest scale available to enhance
the ability to locate wetlands on the photographs. Wetlands observed on aerial photographs
should be checked against the NWI maps recognizing that some wetlands appearing on NWI
maps may not be evident in available aerial photography and vice versa.
Soil surveys and hydric soil lists obtained from the USDA Natural^R.esoupes
,-.','. '*'?';$^- ^: •' ''-1' "
Conservation Service can also be used to identify potential vyetland areipfB|y^l survey map in
conjunction with aerial photographs can be used to identifyfji^as exhii^^fiWric soil and
hydrophytic vegetation respectively.
Once potential wetlands are identified using N
sensing images and other resources, a field survey shoull
information and other potential locations (e.g. topograp
investigated during the field survey. Specific boundari|
PSSb) should be verified (or determined) in the field A a
»r interpre
ucted to ground^pzme
ions and seeps) should be
sification categories (e.g.
nt plant species
completed at this
ce.
used to add wetland
.escriptors) may be assigned
generated. A brief assessment of wetland function;
time. The data collected may then be used to
>|8
A geographic information system (|ip§) or 01
locations to other mapped features of th^|project
to the different wetland 'polygons' occurring o:
these mapped wetlands may then be used as
for impact assessment, and for planning p
two factors. First, since wejjandjboundari
data represent only a snaj^Ptwtime. S
,4K'.•*&••' -^-«|h <^:'
field sur^ej^Jfpp maps?
for generatiM2»35prlcc/wflfe
.e locations and characteristics of
iption of the affected environment,
s. Thejflsefulness of GIS, however, is limited by
ions can change over the years, the GIS
IS is only as accurate as the input data (i.e.,
nterpretaloh). Acknowledging its limitations, GIS is useful
type of wetland, potential impact, or other descriptor.
3.3 Wetland Determination a
3.3.1 Delineation Cr\
ineation
The COE of Engineers Wetlands Delineation Manual (1987 Manual) (Environmental
Laboratory, 1987) defines how the three criteria - hydrophytic vegetation, hydric soils, and
wetland hydrology - are used to delineate wetlands. Under normal circumstances, wetlands
possess at least one positive wetland indicator for each of these parameters, for purposes of the
GWA. The 1987 Manual identifies a number of indicators available for each parameter. This
section presents an overall summary of the three criteria and some of their indicators; however,
the reader is referred to the 1987 Manual for complete details. Wetland delineations may not
necessarily be conducted for all wetlands within a study area. Due to practical matters and costs
associated with intensive sampling, delineations may be focused only on wetlands that could be
impacted by a proposed disturbance. Regardless of the jurisdictional status and whether or not a
wetland boundary is established, there are other characteristics used to describe wetlands within a
1-6
-------
Mining Source Book
Appendix I - Wetlands
discussion of the affected environment. Other methods for describing wetland resources are
discussed in Section 3.4.
Both EPA and COE accept the 1987 Manual as the standard document for wetland
delineation, as of this writing. The reader should be aware that several manuals spelling out
specific methodologies for wetland identification and delineation have been written or proposed
which might someday replace the 1987 Manual if the federal government determine they are an
acceptable substitute. Consultation with the COE or other relevant federal agency ^will help
ensure that delineations are completed using the appropriate manual and techniques.
3.3.1.1 Hydrophytic Vegetation. The delineation proc^^onsider^al of the dominant plant
species occurring at a site when determining the preseaojfflSsence of hy^pplrytic vegetation;?
Hydrophytic vegetation refers to plants that are adaptedjffgrowmgjii anaerobic soil" conditions',
or those conditions that typically exist under prolonged^l inundjiion or saturatton^The/*'
delineation process requires identifying the dominant p:
their 'indicator status.' The indicator status is establish
Species that Occur in Wetlands (USFWS, 1988) and re
occurring in wetlands. A site supports hydrophytic v<
dominant plant species present at the site are more
Other indicators include visual observations of,
morphological adaptations, physiological a
Laboratory, 1987).
latiorP
..to occt
ig in mi
lical
ing at a site and determining
S's National List of Plant
cod of a plant species
50 percent of the
than in uplands.
'saturated conditions,
iture (Environmental
3.3.1.2 Hydric Soils. Soils ex
those created by saturation or in
result in particular soils being c.
ConservationService (now^
Hydric part|
soils (<
within an
recommendec
include a darl
iron and
^hydrl
atbernl
inethe**
ia,gle
'. to projJfged perSi of anaerobic conditions, such as
(pen, distincjpWacteristics. These characteristics
ied as undjgpS Department of Agriculture Soil
Service [NRCS]) nomenclature.
are the NRCS. These lists identify hydric
l) withiri^particular soil survey. Since all hydric soils
lapped at too small a scale to be useful, field studies are
'hydric soils. Common field indicators of hydric soil
jfgray colors), and the presence of colored mottling or
i (Environmental Laboratory, 1987).
Wetland The term 'wetland hydrology' applies to characteristics that
«»ate or imply a Me periodically inundated or the soils are saturated to the surface for
ended period the growing season. Indicators of wetland hydrology often appear
?h the charactejllcs of the site's vegetation and soils - vegetation adapted to saturated
as and ^^pdiibiting hydric indicators. However, direct indicators of wetland
^recorded data (e.g. gauging stations, fioodplain maps) and field data (e.g.
s, watermarks, drift lines) (Environmental Laboratory, 1987). The reader is
vi5^^^>, ,
referred'to Appendix A, Hydrology, for a discussion of hydrological analyses and methodology.
1-7
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Mining Source Book
Appendix I- Wetlands
3.3.2 Delineation Methods
The 1987 Manual establishes three approaches to completing a wetland delineation. The first,
onsite inspection unnecessary, may be used when sufficient information is available about the
site to make a wetland determination. This approach is usually not used, as all the necessary
information is seldom available. The other two methods, which are typically employed, are the
routine onsite and comprehensive determinations (Environmental Laboratory, 1981^
3.3.2.1 Routine. The routine onsite approach to delineating wetlajiiSs^
of existing data including US Geological Survey (USGS) qfiplrangle
surveys, gauge data, and aerial photography. Resource management
federal) may also be sources for additional information jfi a partic
be evaluated to determine whether an 'atypical situatio^msts,jSpTis, have vi
and/or hydrology been altered by recent clearing, farmi:
diversions, filling, diking/ditching, etc.) or natural the area from having
wetland characteristics to non-wetland characteristics. requires the
completion of additional analytical procedures, which^m! not%&£tttnuoarized here (see Section
F of the 1987 Manual).
with a review
maps, soil
state, or m
There are two procedures for field
assessment area. The delineation processjpr areas
homogeneous with respect to vegetationjtsoils,
locations of individual plant commu|pl(es on a
establishing sample points in reprefilptative IgfPtions
collecting data for vegetation, sofls, and hy
point. Dominant plant speciesxare identifi
whether the site is dominated by j(more
excavated to determine
iydrc
on the Size and complexity of the
id thought to be relatively
fine, involves sketching
.cterizing each community type by
igurel-l). Sampling involves
ihipleting a data form for each sample
dicator status determined to establish
it) hydrophytic vegetation. Soil pits are
laracteristics. Soil pits are also used to
demonstratethe presence of and"if present, depth to saturated soil. This observation can also be
used in support«ojEarwetiand hydrotegsr f^termination. Sample locations demonstrating positive
results for alljtoee criteria are considered wetlands. After sample points have been established
in each plant community, boundaries must be established between upland and wetland
communities. Where botaidaries between the vegetation types are unclear, additional sample
points are completed to ascertain the absolute boundary. A map is then completed depicting the
locations of wetlands within the study area. From a practical standpoint, the boundaries should
be staked or flagged and surveyed in order to have adequate location data for use in permitting
and when detailed project designs are being drafted (Environmental Laboratory, 1987).
Areas greater than five acres require the establishment of a baseline and transects to frame
the sampling regime (see Figure 1-2). The length of the baseline, number of transects, and
spacing of transects depend upon the size of the study area. Each community type must be
sampled within at least one transect. Under this approach, sampling occurs within each plant
community along each transect, and a data form is completed for each sample location.
Boundaries between uplands and wetlands are established as described in the preceding
paragraph (Environmental Laboratory, 1987).
1-8
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MjningSource Book
sndtxl- Wetlands
Fi
Routine wetiMTdetenni
Jllllf
and with reSwely horn
h
jundertak
; or where
Under the
[Tie vegetatiq
unities that
acres or less
, soils, and
a projectjSfres than would typically be necessary. A comprehensive
study where there is a likelihood of litigation at some point in
the or where a be suspected of providing habitat for threatened or endangered
isive method, the preliminary work is completed as in a routine
mst be characterized to determine the number and location of plant
!o be sampled. A baseline and transects are then established, based on the
iple data are collected on a different form than that used in routine
case, the information is recorded in greater detail and includes species
Ind density data for the different vegetation layers (trees, saplings/shrubs,
grasses/forbs, and woody vines). Vegetation data are then summarized on a second data form in
making a determination on the presence/absence of hydrophytic vegetation. Soils and hydrology
data are recorded similarly to the process used in the routine approach. Boundaries between
wetland communities and non-wetland communities are determined by observing distinct
changes in vegetation or topography, or completing additional sampling points. Boundaries
1-9
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Mining Source Book
Appendix I - Wetlands
between transects may be developed based on surveying a contour between sample points across
transects or again conducting additional sampling (Environmental Laboratory, 1987).
The results of wetland delineations should be summarized in a report that includes a map
and copies of the data forms. The report may then be used to support a Section 404
permitapplication and/or environmental impact analysis.
V> V-Y •*
etland l^pimnation for assessment areas greater than
ex vegetation, soils, and hydrology.
Describing Wetlands
Wetlands represent a transitional zone between uplands and aquatic habitats and tend to
occupy a relatively small percentage of the landscape (Mitsch and Gosselink, 1993). However,
in some areas, such apportions of Alaska and within floodplains, wetlands may encompass large
areas. Different classification schemes may be used to describe wetland resources in each of
these cases. The so-called Cowardin system is one method of classifying wetlands and
deepwater habitats; this method is used to describe wetlands on NWI maps (see Section 2.0). In
some cases, vegetation classification schemes, such as The Alaska Vegetation Classification
(Viereck et al., 1992), may be more appropriate than the Cowardin system. For example, in
Alaska, the Alaska Vegetation Classification is tailored to local conditions and plant species and
therefore allows the user to be more specific in the description of wetland resources. Other
descriptors, in addition to a classification scheme, include wetland functions (see below). The
1-10
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Mining Source Book
Appendix I- Wetlands
. -«-. .—,
descriptions that result from gathering this information provide a basis for comparing the types of
wetlands present and will aid in assessing the potential impacts (Section 4.0). The approaches to
classifying and describing a project's wetlands will be discussed in more detail below. Note that
all wetlands, regardless of jurisdictional status should be described.
3.4.1 Cowardin System.
The Cowardin classification scheme characterizes both wetlands and deepwater habitats
using a hierarchical approach (Cowardin et al., 1979). The Cowardin scheme does not include
nor should it be used to determine jurisdictional status of wetlands andjofier-waters of the United
States. Indeed, the Cowardin classification scheme does n0|pe the sap|fj|«ition for wetlands
as used by the COE and EPA in accordance with the C\\gpflnder twictef^atkm scheme, J
systems represent the first tier followed by subsystems, tjisses, aM^clcS^^ornmance^je
and modifier constitute the lowest tiers of the scheme. succejiive tier provides-airiater
level of detail for individual wetlands. Classifying weti^^tH^fg the Cowardin sy^§mr
facilitates comparisons with wetlands exhibiting similar"e|^ifc§tics both within and outside
the project area.
Cowardin's scheme includes three freshwat
riverine. Palustrine systems are commonly
encompass all non-tidal wetlands and tidal
0.5% that are dominated by trees, shrubs
lakes and reservoirs. Lacustrine syste:
topographic depression or dammed jM8r charmi
emergents. If smaller than 20
systems include wetlands and di
systems exclude wetlands
considere^W^trine. G
Jems' -
irshes
dominate an if
hydrology (e.
^lacustrine, and
, scraps or bogs. They
eafrderived salinity is below
-acustrine systems include
0 acres in size; situated in a
escribe
, shrubs, and persistent
"generally defined by depth. Riverine
Contained within a channel. Riverine
persistent emergent, which would be
the substrate or dominant life form of
wetlam
xamples of classes include forested, scrub-
ttorn. Dominance type refers to the plant species that
T may provide insight to the individual wetland's
.ver). An example of a willow thicket classified under
iw-dominated palustrine scrub-shrub (PSS). A beaver pond
aquatic bed (PAB) with a beaver modifier (PABb).
\ystem.
%%%r
Alaska Yjiftation System also uses a hierarchical approach to classification but
vegeJaj^Kommunities rather than wetlands in particular (Viereck et al., 1992). This
Sant communities with wetland characteristics to a limited extent in its second
more so in its fourth tier. The first two tiers (Levels I and II) describe the life
_
form of the dominant community. Level I consists of Forest, Shrub, and Herbaceous; Level 2
includes descriptors of these life forms - such as broadleaf or needleleaf; tall or low scrub; and
graminoid or forb communities. Level III describes the degree of canopy closure and, in some
cases whether it occurs in wet areas. Levels IV and V describe the dominant species and the
associated vegetation, respectively. Examples of descriptions based on the Alaska Vegetation
1-11
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Mining Source Book
Appendix I - Wetlands
System include Closed (canopy) Sitka Spruce Forest and Open Tall Alder-Willow Shrub. Using
this classification as a basis for the description of the environment can include vegetation in
general and also wetlands, particularly where wetlands encompass a large portion of the project
area. The Cowardin system may be applied on top of the plant associations described using the
Alaska classification system. For example, an Open (canopy) Tall Alder-Willow Shrub
vegetation community that occurs in wet conditions would be consistent with Cowardin's
Palustrine Scrub-Shrub class.
*"•!&*?$
Where wetlands cover a large portion of the landscape, a routine delineatijpif may be
undertaken using these vegetation units as the basis for the delineation. "Since jtriis method could
potentially over- or under-represent the extent of wetlands,s|it;site, an agreement should be
reached with the COE and lead agency if this approach isijpioposed. TfeejCOE wijl require that a
field delineation be performed for all wetlands potentialipimpacted b^the project.
3.4.3 Function Assessment.
Wetland functions are physical, biological or ch
Examples of wetland functions include but are not linked to,
groundwater recharge/discharge, or flood storage
and/or chemical processes or conditions, are
described qualitatively. Wetland functional
a necessary component of wetland analysj|f
functions is the Federal Highway Adrrm|Itrati
(WET) or some modification thereojjrlphe Hyi
id fund
quant
;sal
; that occur in wetlands.
Jdlife habitat,
f sical, biological,
are often
• comparing wetlands,
rfon
A cor
?eomor
ch to assessing wetland
id Evaluation Technique
IGM) method is a quantitative
approach to wetland functional assessment cusently und^ievelopment. HGM assesses the
functional level for individual wetlands withm^iifferejM^etlaiid 'classes' wetlands. Analyses
completed using HGM are not directly compafebfe^m WET analyses. These two methods or
-#^$- "** A j ^ '"^'^xs"^/ '',^
modifications thereof, are the typical methods^&sfirfo assess and describe wetland function;
however, there is no required-method for describing wetland function.
3.4.3.1 Wetland Evaluation Technique (WET). The FHWA method for wetland functional
assessment, WET, provides a procectee for converting typical wetland field observations (e.g.,
wildlife, plant species, Sicreatton) into preliminary statements regarding the wetlands probable
functional value (FHW^. 1983a), WET rates a broad range of functional attributes and values
on a scale of high, moderate, and low (Mitsch and Gosselink, 1993).1 Each wetland function is
rated on three attributes: social significance; effectiveness; and opportunity (Mitsch and
Gosselink, 1993; FHWA, 1983b). Social significance assesses the societal value of a wetland in
terms of economic value, strategic location, or special designation (Mitsch and Gosselink, 1993).
Effectiveness relates to the wetland's capacity to carry out a function because of its physical,
chemical, or biological characteristics (Mitsch and Gosselink, 1993). The degree to which a
wetland functions at its level of capability is assessed for the opportunity rating (Mitsch and
Gosselink, 1993). WET has some limitations including its limited transferability from site-
1 Functional attributes include: groundwater recharge and discharge; flood storage and desynchronization; shoreline anchoring
and dissipation of erosive forces; sediment trapping; nutrient trapping and removal; food chain support; habitat for fisheries and
wildlife; active and passive recreation; and heritage value (FHWA, 1983).
1-12
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Mining Source Book
Appendix I- Wetlands
specific to landscape level analysis (Mitsch and Gosselink, 1993) and comparability with
analyses completed using other techniques. The WET manual often uses the terms function and
value mter-changeably. See Section 2.1 for a discussion of these terms.
., , ~ . - • ,«w«y. HGM represents a new approach for evaluating
wetland function. The HGM approach focuses on comparisons among wetlands with similar
characteristics (i.e., within the same wetland class) and includes methods for assessing human
induced changes to wetland functions (Brinson, 1996; Brinson, 1993). HGM uses indicators
from the literature and field measurements in describing measurable properties^a particular
function within a particular wetland class. These measurements and modefeare calibrated on
regional reference wetlands and then used to develop an index of toey^ for each wetland
function. This information can be used not only to describe me extent telH^particular ^
wetland is performing specific functions but also to estabish mitigation goa^vahiate the^ "
mitigation potential for different sites, and monitor pro jiss of mitigation activities (Rheinhardt
etal.,1997). *&&*»•*-. ^ ^» .
HGM focuses on comparing wetlands within
riverine) rather than trying to compare characteristics afross
may be rated for riverine wetlands but might not beymtsjdered
wetlands within the depressional class. The Hjj
available for broader use within the foreseeaJIP
X>r^"
4.0 IMPACT ASSESSMENT
4.1 Impact Assessment
Im
mine o
occur to wi
result from
g
;. depressional or
.example, a fish habitat
types of seasonal
lopment but may be
TIGATION
Filling a wetlj
the other 1
species«mposition of
hydrjipgy upstream woi]
to wetland resources from all aspects of
'sure. WHile there are many sources of impacts that may
pries of impacts are direct and indirect. Direct impacts
particular point in time and at a particular location.
be considered a direct impact. Indirect impacts on
removed from the point of disturbance. The change in
wetlands over a period of years in response to changes in
lonsidered an indirect impact.
Impacts.
Mining-related activities may result in direct or indirect impacts to wetlands.
fclude exploration, geotechnical drilling, construction and operation of
heap leaching, surface water diversions; withdrawal of groundwater; and
accidental and permitted discharges. The results of these types of activities include direct
wetland loss through filling or draining; changes to the hydrologic regime with subsequent
changes in flora and fauna; habitat fragmentation due to human encroachment; and changes in
sedimentation patterns. Identifying, attributing, and describing the short- and long-term range of
environmental impacts to individual resources is the key to impact assessment.
1-13
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Mining Source Book
Appendix I - Wetlands
Impact assessment relates to a wide range of questions and while many would be
applicable to most projects others will depend on the specific conditions related to each
individual project. Some of the relevant questions include:
• How many acres of wetlands will be directly and/or indirectly impacted by fill
activities?
To what extent will changes in surface water flows affect wetlands within (and
outside) the project area?
• Will groundwater withdrawals influence wetlands and if so, to what extent?
• Will sediment loading to particular wetlands be increased? * V. »*"'
To what degree would mining-related activities affect habitat values?
• To what degree would mining-related activities affect water quality (Le.,
temperature, toxins, etc.) within wetlands?
Descriptions of potential impacts to wetlands
loss (acres filled or drained) and in loss of function. Th
relatively straight forward and tends to only address di:
more complicated but necessary to adequately addres
tend to be greater than the sum of their parts and,
exist between wetland acreage and functions
have either a greater or lesser effect on the
halving them. This situation needs to be epfsiderei
functions. Likewise, the loss of all or of a w
wetlands and other aquatic areas, aniillSen
The most practical approadfrto det
each type of activity that could cause imp;
subtle. Obvious items incto^Mj^fculating
; the various facilities
resented in ternisxof absolute
lysis is quantitative and
ile the latter is significantly
or example, wetlands
not necessarily
of a wetland may
wetland than simply
itial impacts to wetland
functions of other
eyond its boundary.
,. . .•; /.
diversions ana
"
the• sstent of impacts to wetlands is to assess
liecklist' should go from the obvious to the
er of wetland acres that will be filled to
letermining of the extent to which surface water
will affect wetlands. Less obvious items might include
determining the|^^^^Chumarl^3^^pfaient on habitat values, assessing the potential for long-
term changesJ0^^^^^^drology|a^I projecting the results of permitted discharges over the
long-temL^feelli£fl^^W^?etland impacts should also be considered and discussed. Some
impacts may only occur during construction (e.g., noise from construction equipment), while
others could continue throughout the life of the project or longer. For example, fill used to
construct a wetland crospnglnay only be needed during mining operations and could be removed
upon closure. Such an*inpact would be considered temporary compared to a wetland
permanently buried under a waste rock dump. For example, impacts to a forested wetland would
likely require more time to recover than impacts to an emergent marsh. This aspect also requires
consideration during the mitigation process.
Ultimately, the analysis should summarize the impacts that are anticipated by class or
category of wetland. The direct impacts may be presented in tabular form, similar to that
presented in Table 1-1. Indirect impacts should be clearly described and include the type of
wetland impacted, size of impact area, description of functions to be impacted, and the source of
the potential impact. All of the discussions should indicate whether the impacts would be
1-14
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Mining Source Book
Appendix I - Wetlands
^^^^^^^^^•^••M«aBHa^^^H^^^^HHM^BH^^^Hvll^^^^^HBK^H^H^v^HIHMB^^^^^^^H
temporary (e.g., noise during summer construction), short-term (e.g., mowing of herbaceous
weS° K 10"g;term (6-g-' sedimentati°n from erosion of exposed soil), or permanent (e.g.
wetlands buried by construction of buildings).
Table 1-1. Example of Direct Impacts Table for Wetlands
4.1.2 Cu
in terms of
"*£?
individual imp£
1992). Pror
because jaPcumulativi
. . ..iF T , . . •»
activijjls. In their ratioi
technically sound approf
t impact analyses should also be considered and described
Cumulative impacts are defined as the sum of all
space, including those of the foreseeable future (EPA,
de permitting process by the COE resulted in part,
small isolated wetlands, through permitted and unpermitted
roposing these changes, the COE stresses that the "only
cumulative impact assessment is on a watershed basis (Federal
cumi
/•
fepact analysis should consider impacts to the resource in the context of
lave occurred or could foreseeably occur in the area. For example, a
'could result in the loss of half of the forested wetlands in a study area. The
Plfimpact analysis may indicate that a different project, also in the planning stages or
already occurring/completed, would also cause the loss of a large portion of the same forested
wetland. In this case, the cumulative impact may be much more significant that the impact
caused by either project individually. Cumulative impacts to wetlands may be addressed by
considering the extent of impacts on wetland classes and function within a particular area - the
boundaries may include a drainage basin, watershed, or some other land management unit. The
1-15
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Mining Source Book
Appendix I - Wetlands
boundaries of the cumulative impact area and the sources of potential cumulative impacts are
typically identified in conjunction with the lead agency at the beginning of the actual
environmental impact assessment process.
4.2 Compensatory Mitigation
Section 2.2 introduced the concept of mitigation in terms of the Guidelines and the
COE/EPA MOA. Within this framework, mitigation usually refers to avoidance, jBpnimization,
and compensatory mitigation. The two former terms were discussed pre^iously|while this
section focuses on the latter. Compensatory mitigation refer|,to the 'enhancement, or
creation of wetlands to restore or replace functions of unav>01«fc|ble wetland
impacts by a particular project. No net loss of resource va|pe"requires Jf
assessment of wetland functions and wetland delineatio||le performelfas me|j
A description of wetland functions and delineation of bpfadariesjipmtifies res
be impacted and catalogues what will need to be replaci^^^^^^nsatory mitigal^^^equired.
Compensatory mitigation is an important compo:
applicant demonstrates avoidance and minimization o
type of compensatory mitigation will generally bej;<
authorization from the COE.
Compensatory mitigation requin
on an individual project basis, usually
mitigation often relates to the size o
amount of wetland impacts expecl|||rThe
and temporal rate of replacemen||pf mitig;
considerations in detenninimrelfeired
<«(sjjrS c jSSS.-(r-i,\.i!K-
mitigatioammcess 01 a^
not neo
assessment. After an
mt practicable, some
CWA 404
: determined by the COE
:>mment. The extent of
. wetlands, and the degree and
success or failure (i.e., level of risk
^replace impacted functions are also
ie districts require compensatory
^placement) other areas (such as Alaska), may
igation.
Frequeii^p^lreferred^^^^to mitigation is termed on site, in kind mitigation,
•* ^p»»,;«•i-y*!*.;>. ^H^SaB^ 07
which equates^oif^^^p^ie speS^K^haractenstics of an impacted wetland within the project
area. Offfs^e,"inKn^^^^^^ maylbe an alternative when no on site options are available or
practicable. Likewise, '^jiiejjjitf of kind may also be possible, particularly when the functions
and values of such an unljeiitafemg would surpass those of the impacted wetland and where in-
kind is not practicable aad/o/desirable based on identified regional or watershed wetland
functional priorities. Off site, out of kind mitigation is generally the last choice when other
options are unavailable or regionally less desirable. The success of mitigation projects often
relates directly tothe type of mitigation undertaken. Restoration tends to be more predictable
than wetland creation as some wetland characteristics already exist (or existed) at the site.
Establishing an adequate hydrologic regime is one of the keys to successful wetland mitigation;
this can be a difficult task for wetland creation projects, but relatively much easier for wetland
restoration. Enhancement of degraded wetlands is often a more practical approach than creation
because again, the site presumable already possesses some wetland characteristics. A qualified
professional, with experience in designing and implementing wetland mitigation projects, should
be consulted prior to the development of any mitigation plan. Likewise it is often important to
1-16
-------
rr
confer with the regulatory and resource agencies through a pre-application consultation process
before finalizing mitigation plans/design.
5.0 REFERENCES
Brinson, M.M., 1993. A Hydrogeomorphic Classification for Wetlands, U.S. Army COE of
Engineers Waterways Experiment Station, Vicksburg, MS, Technical Report WRP-DE-4.
Brinson, M.M., 1996. Assessing Wetland Functions Using HGM, National Wetland Newsletter,
pp. 10-16.
Cowardm, L.M., Carter, V., Golet, F.C., and LaRoe, E.T.? 1979.
Deepwater Habitats of the United States, U.S. Fish& Wildlife Service
FWS/OBS-79/31 (December 1979),http://www.nwyw^gov/classman.^^
».
i * ^:
Environmental Laboratory, 1987. COE of Engineers Wetlands Delineation Manual, U.S. Army
COE of Engineers Waterways Experiment StatfdC VicksburgCMS, Wetland Research
Program Technical Report Y-87-1.
Federal Register. 1980. "40 CFR Part 230^
Disposal Sites for Dredged or Fill
45(249), 85, 352-85, 353.
Federal Register. 1982. "Title 33^p^igatio^and Nav^)le Waters; Chap. 2. Regulatory
Programs of the Corps Gov|jpintmg Office, Wash., DC, 47 (138),
31,81
Mitsi«rWJ., and Gos
York, NY.
"•y
Gukfelmes for Specification of
.g Office, Wash., DC,
Federal
of
aricl Modify Nationwide Permits; Notice, Department
COE of Engineers, July 1,1998. 36039-36078.
Lyon, John Gr
Mi
and Delineation. Lewis Publishers, Ann Arbor,
., 1993. Wetlands, 2nd edition, Van Nostrand Reinhold, New
id, M., 1995p€omparison of Wetland Areas in Northern Virginia: National Wetland
Versus Field Delineated Wetlands Under the 1987 Manual, Wetland
7,no. 1, pp. 10-14.
Rheinhardt, R.D., Brinson, M.M., and Farley, P.M., 1997. Applying Wetland Reference Data to
Functional Assessment, Mitigation, and Restoration, Wetlands, vol. 17, no. 2, pp. 195-215.
Stolt, M.F. and Baker, J.C., 1995. Evaluation of National Wetland Inventory Maps to Inventory
Wetlands in the Southern Blue Ridge of Virginia, Wetlands, vol. 15, no. 4, pp. 346-353.
1-17
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Mining Source Book Appendix I- Wetlands
U.S. Army Corps of Engineers, and U.S. Environmental Protection Agency, 1990. Memorandum
of Agreement Between the Environmental Protection Agency and the Department of the
Army Concerning the Determination of Mitigation Under the Clean Water Act Section
404(b)(l) Guidelines).
U.S. Dept. of Agriculture, Soil Conservation Service. 1975. Soil Taxonomy, Agricultural
Handbook No. 436. U.S. Govt. Printing Office, Wash., DC.
U.S. Dept. of Agriculture, Soil Conservation Service. 1983. "List of WrjKllctual or High
Potential for Hydric Conditions," USDA-SCS Natl. Bulletin Wash., DC.
U.S. Dept. of Agriculture, Soil Conservation Service. States,"
Misc.Publ. 1491, Wash., DC. jf ^f ^--':-'
U.S. Department of Transportation, Federal Highway ^4^|i8||ption, 1983a. A
Wetland Functional Assessment, Volume 1, March 1983.
U.S. Department of Transportation, Federal Highway A Method for
Wetland Functional Assessment, Volume No. March 1983.
U.S. Environmental Protection Agency, Impact
Assessment: A Proposed Methodol^y, Leibowitz, B.
Abbruzzese, P.R. Adams, L.E. Haglies, andjlfr. Environmental
Protection Agency, Environmental Research Laborapry, Corvallis, OR, EPA/600/R-
92/167 ''" /$
U.S. Fish and Wildlife Service, 1988. Nationaf Species that Occur in Wetlands:
1 988 National Sunrnuay^Report prepareǤ^^.B. Reed, Jr. for the National Wetlands
Inventory, U.S. Fish and Wildlife Service, Department of the Interior, Washington, DC,
Biologicaljleport 88(24). 1
.
U.S. Fish andJWildlife Service, 1998. "NWI Overview " http://www.nwi.fws.gov/overiew.htm,
November 20, 199).
*f '
/•/' *•
U.S.. Fish and Wildlife Service, 1997. A System for Mapping Riparian Areas In The Western
ffUnited States, USFWS National Wetlands Inventory, Washington, D.C., December 1997,
|* http://www.nwLfws.gov/riparian.htm, November 12, 1998.
Viereck, L.A., Dyrness, C.T., Batten,A.R., and Wenzlick, K.J., 1992. The Alaska Vegetation
^Classification, USDA Forest Service, Pacific Northwest Research Station. General
. Technical Report PNW-GTR-286.
1-18
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Mining Source Book
Appendix I- Wetlands
6.0 CONTACTS AND OTHER INFORMATION SOURCES
Code of Federal Regulations - http://law.house.gov74.htm
Natural Resources Conservation Service (http://www.nrcs.usda.gov/) - information available
through Web page or state and district offices.
Society of Wetland Scientists - http://www.sws.org/
U.S. Army COE of Engineers (http://www.usace.army.mil/) .Note that Sacramento District
(http://www.spk.usace.army.mil/cespk-co/regulatory/) has illrmation speggfiglly related to
jurisdictional wetland delineations and 404 permitting: ^-;"
U.S. Environmental Protection Agency, Office of Wate^ttp://www.epa.gov/o^0^/wetlands/)
provides information on wetlands as well as a wetland Hotline Number: l-800-832^§28, email
to wetlands-hotline@epamail.epa.gov
U.S. Fish and Wildlife Service (http://www.fws.gov/) -provideNational Wetland Inventory
maps; may be a source for information regarding potential mitigation opportunities.
USFWS NWI maps are available as paper c^^fmylap overlays, and occasionally as digital
layers. The USFWS NWI homepage (>t^^ww.n.wi.%stgov>e|afems information on NWI
products, available maps, and ordering Jpformatic
USFWS endangered species homf|^e-http^
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U.S. Geological Survey's EJ|Q|flata cent
for
searchi
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.fws.gov/~r9endspp
.cr.usgs.gov/eros-home.html) serves
federal agencies and allows on-line
1-19
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