U.S. DEPARTMENT OF THE INTERIOR 

U.S. GEOLOGICAL SURVEY

Analytical Results and Conceptual Model of Mine Drainage at the Holden Mine,

Chelan County, Washington

By

I.E. Kilburn*, D.B. Smith**, and S.J. Sutley**

Open-File Report 99-348

This report is preliminary and has not been reviewed for conformity with U.S. Geological 

Survey editorial standards or with the North American Stratigraphic Code. Any use of 

trade, firm, or product names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

*Kilburn Associates LLC, 1456 Cassin Ct, Boulder, CO 80303 

**U.S. Geological Survey, Denver Federal Center, MS 973, Denver, CO 80225

1999
CONTENTS

ABSTRACT...1 

INTRODUCTION...!

Site Description and Mining History...3 

Geologic Setting...4

Summary of USGS Geochemical Investigations..^ 

Field and Laboratory Methods (September 1996)...5 

DISCUSSION AND CONCEPTUAL MODEL...6

Major Controls of Mine Drainage at the Holden Site...6 

Geologic Controls... 6 

External Controls...? 

Geochemical Controls...8 

Oxidation of Pyrite... 8 

West Area...9

Portal Water...10

Characterization. ..10

Flocculent Material and Sorption Processes... 11 

Interpretation and Discussion... 12 

Mill Site, Waste Dumps, and Lagoon Area... 14 

Honeymoon Heights drainage... 16 

East Area... 17

Fe-dominant Tailings Seepage... 18 

SUMMARY...20 

ACKNOWLEDGMENTS..^! 

REFERENCES CITED...22

TABLES

Table 1. Analytical data for untreated water samples collected at the Holden mine,

September 1996...26 

Table 2. ICP-AES analysis of filtered and acidified water samples collected at the Holden

mine, Sept. 1996...27 

Table 3. ICP-MS analysis of filtered and acidified samples collected at the Holden mine,

Sept. 1996...30 

Table 4. Secondary sulfate minerals identified at the base of the Holden mill tailings, July

1994...33 

Table 5. Secondary sulfate minerals identified in the abandoned Holden mill, July

1995...33 

Table 6. Secondary sulfate minerals identified in the abandoned Holden mill, May

1996...34
FIGURES

Figure 1. Location of the Holden Mine, Chelan County, Washington... 3 5 

Figure 2. Holden mine site map showing the location of water samples collected in 

September 1996...36
ABSTRACT-The Holden orebody is a relatively low-grade, Cu-Zn-Ag-Au, Kuroko-type 

volcanogenic massive sulfide deposit (VMS) located within the crystalline core of the 

northern Cascade Range, north-central Washington. The abandoned mine and related 

workings lie adjacent to Railroad Creek, a major tributary of Lake Chelan (a large fjord 

lake some 20 km to the east). Because of their pyrite- and sulfide-rich nature, massive 

sulfide deposits such as Holden have an unusually high acid-generating capacity. Under 

oxidizing conditions, water draining these deposits can react with the sulfides to form 

acidic, metal-rich waters that represent potentially significant sources of acid and 

metal-loading in the environment. Detailed hydrogeochemical studies conducted at Folden 

by the U. S. Geological Survey (USGS) as well as preliminary investigations undertaken 

by Dames & Moore on behalf of Alumet Inc., identified numerous mine-related seeps and 

flows of widely diverse compositions at the site. Broadly defined, this discharge can be 

categorized into two discrete groups consisting of: (1) acidic to strongly acidic, 

Fe-dominant seeps at or near the base of the tailings piles; and (2) weakly acidic, 

base-metal-rich effluent draining the mine, mine workings, and assorted waste piles and 

prospects found generally west of the tailings. The mine-related discharge is further 

characterized by a distinct seasonal variation in both chemical composition and magn; tude 

of flow. In general, the lowest pH and highest dissolved solid concentrations (and total 

dissolved mass) coexist with peak flow conditions associated with the spring runoff. As 

the flow and circulation of water progressively abates through the summer and fall, pH 

levels gradually increase, whereas the concentration and mass of dissolved metals decline 

markedly. According to the site conceptual model, the chemical makeup of Holden's acid 

drainage can ultimately be traced to a number of dominant controls that are largely a 

function of ore deposit geology (e.g. pyrite content, structural characteristics, etc.). 

However, seasonal variation in mine water chemistry is for the most part attributed to the 

dissolution and hydraulic flushing of soluble secondary minerals in the spring and their 

precipitation from saturated and supersaturated solutions in the summer and fall.

INTRODUCTION

This short paper and accompanying conceptual model attempts to provide Federal 

and state regulators, land-use planners, and other interested parties a practical 

understanding of the major processes which are believed to effect the evolution of 

acid-mine drainage at the Holden mine. Scientific jargon and complex geochemical 

processes are intentionally kept to a minimum or are greatly simplified; hopefully without 

compromising scientific integrity. In this respect, the conceptual model is based on 

established geochemical principles as well as field and laboratory observations made at 

Holden and elsewhere. However, many of our perceptions regarding the Holden site are 

conjectural in nature, and the model cannot be considered definitive or conclusive. In 

addition, the report provides the tabulated analytical results (tables 1-3) and sample 

localities (figure 2) for mine related effluents collected during the September 1996 U. S. 

Geological Survey (USGS) Holden site investigation. Analytical results from previous 

USGS geochemical studies at Holden are found in Kilburn and others, 1994; Kilburn and 

Sutley, 1996; and Kilburn and Sutley, 1997. The mineralogy of secondary sulfate minerals 

collected at the mine from 1994 -1996 are also included in this report.
Each mine site is a unique geologic and geochemical entity, yet the environmental 

ramifications of acid-mine drainage remain a common and disturbing factor in past ard 

present mineral development. In recent years, reliable accounts linking contaminated mine 

water with declines in aquatic insect populations, periodic fish kills (Arnekleiv and Storset, 

1995) and even cattle deaths (Webster and others, 1994) have provoked considerable 

public sentiment regarding the nations water quality and stability of its aquatic ecosystems. 

In this regard, the United States and other industrialized countries have made a concerted 

effort to curb mine-related pollution by encouraging modern mining methods and enacting 

strict environmental codes or regulations to oversee active and future mining endeavors. 

Nevertheless, the enigma of acid-mine drainage persists, at a magnitude greater than once 

believed, in the form of what Allan (1995) termed "historical pollution" associated with 

inactive or abandoned mine sites. Of particular concern are volcanogenic massive sulfide 

deposits (VMS) such as Holden, a deposit type that has produced some of the most rcidic, 

metalliferous mine drainage on record (Alpers and Nordstrom, 1991) . Because of their 

pyrite- and sulfide-rich nature, VMS deposits have an unusually high acid-generating 

capacity. Under oxidizing conditions, water draining waste piles, underground workings, 

and unmined ore zones of such deposits can react with the sulfides to form acidic, 

metal-rich waters that represent potentially significant sources of acid and metal-loading in 

the environment; jeopardizing not only local water quality, but neighboring aqueous r,nd 

terrestrial ecosystems as well. Moreover, Holden, like many sulfide-rich deposits, is 

characterized by an abundance of metal salts that readily dissolve during episodes of wet 

weather or heavy runoff (e.g. snowmelt), liberating additional amounts of acid and metals 

to the surroundings.

Recent studies at the Holden complex were undertaken by the USGS (1994-1996) 

and Dames & Moore (1997) (at the request of Alumet Inc.) to determine the nature and 

extent of the mine's acid drainage and characterize its aftereffects on the local Railrord 

Creek watershed. In brief, these studies revealed a dynamic and complex hydrologic 

regime, typified by a wide-range in mine effluent compositions that commonly fluctuate 

chemically with the season. Although most of the contaminated discharge can be identified 

with a variety of point sources, the mine-related effluents have been broadly categorized 

by Dames & Moore into two distinct groups based on chemical similarities and general 

proximity. These designated groups are: (1) the East Area, consisting of strongly acidfc, 

Fe-dominant seeps that surface at the base of the three tailings piles ; and (2) the West 

Area, consisting of weakly acidic, base-metal rich water draining the mine, mine workings, 

and various waste piles and prospects located generally west of the tailings (Dames & 

Moore, preliminary and unpublished data, 1998). For simplicity, this report will adopt this 

arrangement. In addition, the paper gives particular emphasis to the spring runoff because 

of its obvious impact on mine drainage compositions and ultimately neighboring Railroad 

Creek. The portal discharge also receives special attention in view of its high base-metal 

content and the myriad of geochemical processes that govern its development. 

Furthermore, using the portal drainage section as a general guide, inferences can then be 

made regarding mine drainage elsewhere at Holden without resorting to undue 

redundancy.
Site Description and Mining History

The Holden deposit is sheltered in a U-shaped, glacially modified valley located 

immediately east of the divide that forms the serrated crest of the northern Cascade Range 

of north-central Washington State. The mine and related workings border Railroad Creek, 

one of the larger watercourses that feeds Lake Chelan, a large landlocked fjord sonn 20 

km east of the orebody (figure 1.). Topographic relief is great in the Holden area 

(approximately 2,500 m) with the mine surrounded by towering peaks and hanging 

valleys. In some of the higher basins and cirques, small glaciers persist and mark the 

headwaters of Railroad Creek's major tributaries, including Copper Creek, Big Creek, and 

Holden Creek. The valley floor is covered by a deep overburden (mostly glacial deb*is and 

talus) that is largely hidden by thick underbrush and scattered stands of timber consisting 

of fir, cedar, spruce, and balsam. Most of the valley walls are abrupt, with rock exposures 

generally replacing timber above 1,200 m. The climate is temperate and typified by warm 

dry summers and cold wet winters. Mean annual precipitation at Holden is about 90 cm 

(35 in), mostly in the form of snow. Because the earliest snowmelt (usually May in the 

Holden area) has a tendency to be enriched in ionic solutes (Harrington and Bales, 1998), 

the entire Railroad Creek basin is probably subject to natural metal-loadings during the 

spring runoff. Access to the site is limited to regularly scheduled boat service out of 

Chelan or by chartered floatplane to the port of Lucerne, a former resort community on 

Lake Chelan. From Lucerne, a graded dirt road negotiates the steep Railroad Creek valley 

to the mine.

Mining possibilities in the Railroad Creek watershed were first recognized in the 

summer of 1887, when a location engineer in search of potential routes for the Great 

Northern Railroad reported and described the weathered, rust-colored gossan marking the 

eventual site of the Holden mine. As accounts of these altered rocks inevitably spread, 

wholesale prospecting efforts began in earnest, with initial claims being staked in the. 

Railroad Creek valley in 1892. Over the next 36 years a number of individuals and 

syndicates held options on the Holden deposit, although efforts to develop the clainr 

proved ineffectual. In 1928 the Britannia Mining and Smelting Co., a subsidiary of the 

Howe Sound Co., acquired the property. Administration of the claims and authority to 

conduct further exploration was promptly passed to another subsidiary, the Chelan Copper 

Mining Co. Rapid development soon followed, including the tunneling and sinking cf 

shafts, the erection of the mill facility to process the ore, and the construction of the 

company town of Holden to accommodate the miners and their families (Youngberg and 

Wilson, 1952; McWilliams, 1958). In 1937, the subsidiary relationship was dissolved and 

the Howe Sound Co. took possession of the property and began active production in 

1938. The mine discontinued operations in 1957 because of escalating production costs 

and a decline in the copper market. Although the ore was of relatively low tenor 

(averaging roughly 1.1 percent Cu, 0.2 percent Zn, 0.2 oz/short ton Ag, and 0.006 

oz/short ton Au) (Nold, 1983) over 212 million pounds of Cu, 40 million pounds of Zn, 2 

million ounces of Ag, and 600 thousand ounces of Au were extracted from 10 million tons 

of ore (McWilliams, 1958). At present, the mine site consists largely of mill tailings, waste 

dumps, portals and shafts, a partially dismantled mill and other surface structures (figure 

2). However, the community of Holden, located on the north side of Railroad Creek
opposite the mine complex, remains quite active and serves as an interdenominatioral 

church retreat administered by Holden Village Inc. (formerly Lutheran Bible Institute).

Geologic Setting

The Holden mine lies within the crystalline core of the northern Cascade Range, a 

region characterized by three major northwest-trending tectonostratigraphic units: the 

Nason, the Swakane, and the Chelan Mountains terranes. The Holden orebody is 

contained within the Chelan Block of the Chelan Mountains terrane (Dragovitch and 

Derkey,1994). The oldest metamorphic rocks exposed in the region, the Swakane E; otite 

Gneiss, is considered early Paleozoic or older based on zircon dating. This unit consists 

primarily of biotite gneiss interbedded locally with hornblende schist and gneiss, 

clinozoisite-epidote gneiss, and quartzite (Cater, 1982). Overlying the Swakane Bicfite 

Gneiss is a complex series of upper Paleozoic metamorphic rocks referred to as "younger 

gneissic rocks of the Holden area*' by Cater and Crowder (1967). This highly folded 

sequence includes schistic and gneissiq rocks of varying compositions along with 

intercalated quartzite and marble lenses. Unconformably overlying the metamorphic units 

are shale, arkosic sandstone, and conglomerate of the Eocene Swauk Formation (Cater, 

1982).

Igneous rocks in the northern Cascade Range vary considerably in age and 

composition. Pre-Tertiary ultramafic rocks of uncertain age mostly are found as small 

masses consisting of gabbro, horablendite, and peridotite that are locally altered to 

serpentine. In addition, ultramafic rocks of probable Eocene age outcrop on the surface 

and in the underground workings of the Holden mine. These younger ultramafic rocVs are 

composed of larger masses of hornblendite and hornblende peridotite and hornblende 

gabbro (Cater, 1982). Regionally, the most common igneous rocks are Mesozoic 

metamorphosed granitic intrusives (orthogneisses) (Nold,1983) including the Triassic 

Dumbell Mountain plutons (the oldest granitoid rocks in the region with a radiomeHc 

date of about 220 m y.) which form a narrow belt of northwest trending rocks of greissic 

hornblende-quartz diorite and quartz diorite gneiss. Tertiary intrusions ranging in age from 

early Eocene to Miocene are also prevalent in the region. These Tertiary intrusives are 

largely granodiorite in composition, but can range from gabbro to quartz monzonite 

(Cater, 1982).

The Holden orebody is interpreted as a metamorphosed, Kuroko-type VMS 

deposit exhaled in a late Triassic island arc setting (Dragovitch and Derkey, 1994). The 

deposit is strata-bound within a sequence of steeply dipping, high-grade metamorphic 

rocks, largely consisting of calc-silicate gneisses and amphibolites. These rocks are more 

or less andesitic in chemical makeup, suggesting andesitic volcanics and related 

volcaniclastic sedimentary rocks as likely protoliths. The immediate host of the mineral 

deposit is a pyritic, sericite-quartz schist sequence within the high-grade metamorpHc 

rocks. Exposures of the ore-bearing schist, which range from 90 to 180 m in thickness, 

can be traced for at least 5 km at the surface. The orebody is stratiform within the schist 

unit and displays the well developed zoning typical of VMS deposits, with a lower 

copper-rich or original footwall and a zinc-rich upper or original hanging wall. This 

primary zoning has endured the ravages of high-grade metamorphism as well as intense
deformation, which has overturned the deposit, resulting in a copper-rich zone structurally 

above a zinc-rich zone (Nold, 1983). Principal ore and ore-related minerals found at 

Holden include pyrite, pyrrhotite, chalcopyrite, sphalerite, and native gold. Accessory 

galena, magnetite, and molybdenite are also present. Gold is spatially associated with 

chalcopyrite in the structural hanging wall, whereas silver mostly occurs with sphalerite in 

the structural footwall (McWilliams, 1958). Mineralization is for the most part 

disseminated, although massive ores are found locally in the zinc-rich zone (Nold, 19P3).

Summary of USGS Geochemical Investigations

The primary focus of USGS studies at the Holden mine was to: (1) describe the 

environmental behavior of a historically mined massive sulfide deposit as it undergoes 

weathering in a temperate climate; and (2) provide the U. S. Forest Service (USFS) with 

information regarding the nature and scope of the site's mine-related discharge. With this 

emphasis, the USGS conducted a reconnaissance geochemical study in and around the 

Holden complex in July 1994 to rapidly identify, at a relatively low cost, the probable 

sources and general chemical makeup of waters draining the abandoned mine (Kilburr and 

others, 1994; Kilburn and others, 1995a,b). A detailed follow-up study was cpncluded the 

following summer (July 1995) in order to assess the extent of and further characterize the 

contamination earmarked by the earlier investigation (Kilburn and Sutley, 1996). 

Additional geochemical surveys were completed in May and September of 1996 to 

address seasonal variation in mine water chemistry. Analytical results and interpretation of 

the May 1996 study are given in Kilburn and Sutley (1997). A complete listing of the 

analytical results (tables 1-3), sample locality map (figure 2), and descriptions of field and 

laboratory methods employed for the September 1996 study are provided in this report.

Field and Laboratory Methods (September 1996)

In September 1996, mine-related discharge and surface flow from Railroad and 

Copper Creeks were collected at or adjacent to the Holden complex in polypropylene 

bottles previously rinsed with 10 % HNO3 . At each site a 60-mL sample, filtered through 

a 0.45 (im acetate membrane filter and acidified with concentrated HNO3 , as well as en 

untreated 250-ml sample were collected. On-site measurements of pH, specific 

conductance, and temperature were also taken. The untreated water samples were 

analyzed for selected anions (F~, Cl", and SO42") by the method of Fishman and Pyen 

(1979) using ion chromatography. Filtered and acidified water samples were analyzed for 

major, minor, and trace elements by the inductively coupled plasma-mass spectrometry 

(ICP-MS) technique of Meier and others (1994) and by inductively coupled plasma-atomic 

emission spectrometry (ICP-AES) using the Briggs (1990) procedure. The ICP-MS 

technique is regarded as a trace method, and is generally preferred in analyzing extremely 

low concentrations of dissolved metals and other elements in the low and sub-ppb range 

(e.g. rare earth elements) that may be dissolved in mine-related effluents, and is 

exceptional in defining the character of primitive or largely uncontaminated waters such as 

creeks and streams. Conversely, ICP-AES methodology is considered more reliable at
determining the high to extreme concentrations of Fe, Al, the base-metals and other 

elements that often accompany degraded effluents such as acid-mine drainage.

Tables 1-3 record the analytical results for each of the water samples collected 

during the September 1996 field season. The mineralogy of secondary sulfate minerals 

identified at the Holden site in 1994, 1995, and 1996 is found in tables 4, 5, and 6 

respectively. In data tables 1-3, if a specific element was analyzed for but not detected, a 

"less than" symbol (<) was entered in front of the lower limit of determination. On the 

other hand, if an element was measured above the highest reporting value, a "greater than" 

symbol (>) was entered in the tables in front of the upper limit of determination.

DISCUSSION AND CONCEPTUAL MODEL

The following interpretative analysis, or conceptual model, is based on 

observations and data compiled by the USGS (referenced above) as well as preliminary 

data provided by Dames & Moore on behalf of Alumet Inc. Seep and surface water quality 

data obtained from these independent investigations proved remarkably compatible 

(especially considering that the USGS utilized sampling methods and protocols better 

suited to reconnaissance geochemical surveys as opposed to the more rigid Quality 

Assurance/Quality Control (QA/QC) applications required of Dames & Moore) and can 

be used interchangeably in a nonrigorous manner to illustrate prevailing conditions ?t 

Holden. Because Dames & Moore collected important, site-specific flow rate information 

not included in the USGS studies, Dames & Moore water data is preferentially applied in 

this report when characterizing mine-related drainage (and cited as "preliminary and 

unpublished data"). A word of caution, this paper frequently refers to mine effluent 

compositions in terms of concentration and/or mass; they are not equivalent quantities or 

units. To avoid confusion, concentration simply concerns the relative amounts of solute 

(in this case, dissolved metals) and solvent (water) in Holden's mine drainage. Mass 

applies to the total amount of dissolved matter in a solution, and is not a function of 

volume.

Major Controls of Mine Drainage at the Holden Site

The evolution of the diverse, metalliferous Holden discharge is contingent on many 

complex, often obscure geochemical and geologic processes. Because these processes or 

controls may be unique to each mine site, a rigid "off-the-shelf' approach to 

characterization and understanding would be impractical and possibly misleading. With 

this caveat in mind, a short description of the dominant factors controlling the 

development of the site's mine drainage compositions was devised based on the 

non-specific guidelines outlined in Plumlee and Nash (1995). These controls, which are 

largely a function of ore deposit geology, are summarized below.

Geologic Controls

 Pyrite content. Holden, like most VMS deposits, is characterized by an 

abundance of pyrite. The oxidation of this mineral not only releases large
quantities of Fe to the environment, but also has the potential to generate the most 

acidic mine drainage found in nature. An obvious manifestation of this weathering 

process is found at the base of the mill tailings, where strongly acidic, Fe-ricb seeps 

are common. Because of its importance, a brief profile of pyrite oxidation is given 

in the next section.

Host rock buffering capacity. Host rocks associated with the Holden deposit 

have a low buffering capacity which is consistent with most VMS models. Tl ;s not 

only translates into lower pH solutions, but also tends to stabilize the dissolved 

metal content of mine-related discharge by restricting pH dependent precipitation 

and metal-partitioning reactions.

Structural and physical characteristics of the mine and orebody. Extensive 

underground workings and fractured host rocks associated with the Holden nine 

permit easy access for weathering agerits such as circulating groundwater and 

atmospheric oxygen, thereby promoting oxidation and metal leaching reactions.

Base-metal sulfide content. At Holden, mine related effluent west of the tailings 

impoundment's is characterized by relatively high levels of dissolved Cu, Zn, and 

Cd. The amounts and proportions of these heavy metals in solution can be directly 

traced to the chemical weathering of the base-metal sulfides chalcopyrite (Cu) 

and sphalerite (Zn, Cd) inherent in the Holden orebody.

Secondary mineralogy. The Holden complex is characterized by an excess of 

soluble secondary sulfate minerals derived from sulfide weathering and related 

acid-generation (including Fe, Cu, and Zn phases). The partial or complete 

dissolution of these efflorescent metal-salts (which store acid and metals in the 

solid state) during periods of cyclic runoff or seasonal storm events greatly 

increases the acidity and metal content of mine-related discharge, which in turn, 

may impact nearby Railroad Creek.

External Controls

Climate. Holden experiences highly seasonal fluctuations in weather that are 

typically associated with Temperate Mountain Zones, including cold wet winters 

and hot dry summers. These conditions favor sulfide oxidation, the development of 

metal salts, and provide seasonal pathways for metals migration.

Mining and milling methods practiced at Holden certainly encourage and 

accelerate natural weathering processes by providing easy access to sulfide 

minerals in the form of extensive underground workings, mill tailings, waste 

piles, and even concentrated ore material.

Topographic relief is great in the Holden area, influencing not only the shape and 

position of the local ground water table, but also controlling to some degree the
extent to which the mine and mine workings are exposed to oxygenated ground 

and surface waters.

Geochemical Controls

 Mineral precipitation and sorption reactions play an active role in substantially 

tempering the dissolved metal content of Holden's mine drainage. The formation 

of Al- and Fe-rich flocculent material in the portal drainage is a highly visible . 

example of these metal partitioning reactions. Because of their impact, a short 

commentary regarding sorption processes is detailed later in this report.

Oxidation of Pyrite

The major cause of acid mine drainage, surface and ground water contamination, 

and the formation of acid sulfate soils at the Holden site can ultimately be traced to the 

oxidation of pyrite. This is a complex biogeochemical process not thoroughly understood 

in natural settings, involving a number of oxidation-reduction reactions enhanced by 

bacterial catalysis. Because of its profound impact, a brief overview of this chemical 

weathering phenomenon is considered an essential complement to any conceptual model 

addressing mine drainage at Holden. The overall pyrite oxidation process is frequently 

described by the following reaction:

FeS2 + 15/4 O2 + 7/2 H2O => Fe(OH)3 + 2 SO42- + 4 H+ (1)

in which insoluble ferric hydroxide and sulfuric acid are produced by the reaction of pyrite 

and water, in the presence of oxygen. For every mole of pyrite that is oxidized, four moles 

of H+ are released to solution. Few reactions in nature produce this amount of acidity. 

However, this symbolic representation is somewhat misleading as the reaction does not 

proceed as directly or as simply as the equation suggests. Pyrite oxidation actually 

progresses via a sequence of intermediate steps as summarized by:

FeS2 + 7/2 O2 + H2O => Fe2+ + 2 SO42- + 2 H+ (2)

in which pyrite is initially oxidized by oxygen, liberating S° that is then oxidized to sulfate, 

creating an acidic ferrous sulfate solution. The reduced or ferrous iron (Fe2+) in reaction 

(2) may then be oxidized to ferric iron (Fe3+) as shown by:

Fe2+ + 1/4 O2 + H+ => Fe3+ + 1/2 H2O (3)

Ferric iron produced in reaction (3) may now act as an oxidant, perpetuating and 

intensifying the oxidation of pyrite (Carrels and Thompson, 1960; Smith and Shumate, 

1970) as indicated by the following equation:

FeS2 + 14 Fe3+ + 8 H2O => 15 Fe2+ + 2 SO, 2' + 16 H+ (4)
Reaction (4) is rapid (Alpers and Nordstrom, 1991) but limited by conditions imposed by 

the rate determining step, reaction (3) (ferrous to ferric). Under weakly acidic and alkaline 

conditions, most of the ferric iron produced by reaction (3) is lost by precipitation of 

insoluble ferric hydroxide and oxygen remains the dominant oxidizer of pyrite. In more 

acidic environments the rate of ferric iron hydrolysis drops, and at pH <3 ferric iron is the 

principal oxidant of pyrite. Oxidation of ferrous iron by oxygen proceeds very slowly at 

this point, with pyrite (reaction 4) reducing ferric iron faster than it can be replenished. If 

enough pyrite is present, all the ferric iron will be reduced and reaction (4) abruptly 

terminated (Nordstrom, 1982). However, acidophilic, iron-oxidizing bacteria 

(Thiobacillus ferrooxidans) may act as catalysts and accelerate the ferrous oxidation rate 

up to six orders of magnitude (Lacey and Lawson, 1970; Singer and Stumm, 1970), so 

that the regeneration of ferric iron is greater than its reduction by pyrite, making pyrite 

oxidation under these conditions (reaction 4) a self-sustaining process. When the pyrite is 

completely weathered or oxidized, the remaining ferric iron is quickly hydrolyzed, 

producing insoluble iron hydroxide:

Fe3+ + 3 H20 => Fe(OH)3 + 3 H*" (5)

The chemical weathering of pyrite generates large amounts of sulfuric acid and 

ferric sulfate, strong solvents that not only perpetuate the oxidation of pyrite, but also 

leach and hasten the oxidation of other metal sulfides such as sphalerite (Guilbert and 

Park, 1986):

ZnS + 2 Fe3+ + 3 SO42" + H2O + 1.5 O2 => Zn2+ + 2 Fe2+ + 2 H+ + 4 SO42" (6)

Reaction (6) is inferred to take place at the Holden site and is considered a prominent 

factor in determining the composition of the areas mine drainage.

West Area

The West Area, located for the most part west of Tailings Pile 1 and the Copper 

Creek diversion (figure 2), is characterized by weakly acidic, base-metal rich drainage with 

little or no measurable Fe. This discharge is highly seasonal both in chemical composition 

and volume of flow. The West Area is further marked by a plethora of soluble secondary 

sulfate minerals (including Fe, Cu, and Zn phases) (tables 4-6) that are found as 

disseminations or crusts near the base of the tailings and in the vicinity of the lagoon, or as 

mineralogically complex aggregates in the abandoned mill (Kilburn and Sutley, 1996; 

Kilburn and Sutley, 1997). Fluctuations in water chemistry suggest that the underground 

mine workings may also host an abundance of soluble metal-salts. In the spring, the West 

Area is commonly overrun with seasonal seeps and overland surface flows. However, this 

section will only address major point sources of migrating drainage including: (1) the mine 

portal; (2) the mill and surrounding waste piles; (3) the lagoon area; and (4) the 

Honeymoon Heights drainage area (figure 2).
Portal Water

Over much of the year, mine drainage flowing from Holden's main portal (1500 

level) is believed to be the major point source of base-metal loadings to Railroad Cr^ek 

(figure 2). Field and analytical data compiled by Dames & Moore in 1997 suggest tl at as 

much as (in kg/day) 0.40 Cd, 20 Cu, and 74 Zn may enter Railroad Creek via the pcrtal 

drainage during discrete periods of the spring runoff. The exact origin of the portal 

effluent is uncertain, although much of the water is probably derived from upgradiert 

meteoric sources (including snowmelt, rainfall runoff, and direct precipitation) that gain 

entry to the mine through faults, fractures, and mine related surface apertures (Dames & 

Moore, preliminary and unpublished data, 1998).

Although an understanding of the many processes (chemical and physical) that 

influence the composition of the migrating mine waters is far from complete, sufficient 

data is available to characterize this discharge and make some general inferences regarding 

its evolution, including primary sources and potential sinks of dissolved metals.

Characterization

Water emerging from the main portal of the mine (1500 level) proceeds rapidly 

downhill nearly a quarter mile before flowing directly into Railroad Creek. The volume or 

magnitude of the portal discharge is highly seasonal, with peak flow occurring during the 

snowmelt-triggered spring runoff and visibly ebbing in the fall and winter months as 

upslope conditions stabilize. Perennially suspended in this outflow or adhering to rocks 

and debris the length of the drainage is a thick, tan-white, flocculent substance (floe) 

identified chemically as amorphous Al hydroxides intermixed with lesser amounts of Fe 

hydroxide precipitates (Kilburn and others, 1995a,b; Kilburn and Sutley, 1996).

Analysis and interpretation of portal effluent sampled by Dames & Moore in May, 

July, and September of 1997 depict an Fe-poor, base-metal rich system that exhibits 

significant seasonal variation in dissolved metal content (both in concentration and mass), 

pH, and degree of base-metal attenuation between the mine and Railroad Creek (Dames & 

Moore, preliminary and unpublished data, 1998). These observations are compatib'e with 

historic USGS findings (Kilburn and Sutley, 1996; Kilburn and Sutley, 1997). Of 

particular interest is the drastic change in water chemistry between May and September. 

This span is marked by a progressive decline in dissolved base-metals coupled with a 

steady rise in pH. A good illustration of this seasonal shift or variation in mine water 

chemistry can be elicited from water data gathered at the portal entrance. Water sairnled 

during the spring runoff (May) proved weakly acidic (pH 4.8) and contained dissolved 

concentrations of (in jug/L) 81.2 Cd, 5,780 Cu, and 14,900 Zn. In comparison, samples 

collected in July were characterized by a higher pH (5.8) and diminishing Cd (22 jug/L), 

Cu (907 M-g/L), and Zn (5,440 \igfL) concentrations. By September, with the pH at neutral 

(7.0), the portal effluent only carried in solution (in jug/L) 8 Cd, 77 Cu, and 3,280 Zn 

(Dames & Moore, preliminary and unpublished data, 1998). More importantly, the 

collective mass of dissolved base-metals passing out of the portal (Cd, Cu, and Zn) 

declined by approximately 95 % between May and July, and another 74 % from July to

10
September. In contrast, seasonal attenuation of base-metals from the aqueous phase 

(chemical metal-partitioning) between the mine and Railroad Creek proceeds in a less 

predictable and consistent manner, typified by : (1) considerable loss of base-metals (Cd, 

Cu, and Zn) between the mine and Railroad Creek in the spring; (2) little or no depletion 

of base-metals along this passage in mid-summer; and (3) significant attenuation of Cu in 

the fall.

The incremental rise in pH that characterizes the portal discharge between May 

(pH 4.8) and September (pH 7.0) is significant and may have important environmental 

implications. Because the pH scale is simply an abbreviated computation (reflecting the 

activity or effective concentration of the free, uncomplexed hydrogen or hydronium ion) 

the true measure of this increase is somewhat diminished. By expressing pH in term0 of 

molarity (moles per liter), however, the actual activity or concentration ([ H+] by 

convention) of hydrogen ion in the May and September portal discharge can be established 

and a more realistic comparison made. Utilizing this approach, it was determined tint the 

May discharge (1.6 x 10~5 mol/L IT1") was 160 times more acidic than the Septembe*" portal 

drainage (1 x 10~7 mol/L H^"). This is particularly meaningful because the hydrogen ion 

activity or [ H+] is considered a master variable in determining the composition of anueous 

systems. For example, the increase in pH from spring to fall would produce a reciprocal 

decrease in the solubility of many dissolved species and accelerate metal-partitioning 

reactions (such as precipitation and sorption), both of which would substantially mitigate 

the dissolved metal load of the mine effluent.

Flocculent Material and Sorption Processes

Although an array of geochemical processes (such as inorganic and organic ion 

exchange and solution-gas interactions) may play a part in limiting the mobility and 

concentrations of dissolved metals in the Holden portal effluent, the formation and 

subsequent flocculation of metal-hydroxide minerals is the most obvious manifestation of 

metal partitioning and/or surface complexation from the aqueous phase. The ubiquitous 

flocculent material, which occurs as clotlike masses or loosely aggregated clusters cf Aland Fe hydroxides in the portal drainage, probably precipitated as a result of pHdependent solubility reactions (Smith and others, 1989). The natural attenuating properties 

of hydrous-metal oxides is amply documented (Levinson, 1974; Rose and others, 1T79; 

Smith and others, 1994) and their impact on the portal discharge and ultimately Railroad 

Creek cannot be minimized. In this regard, the portal water floe is not only instrumental in 

controlling aqueous Al and Fe concentrations, but also serves as an effective sink for many 

dissolved i^nic species through coprecipitation and sorption reactions. Analysis of portal 

drainage floe collected by the USGS in the summer of 1995 clearly demonstrates these 

scavenging properties, with constituent base-metal concentrations as high as (in ppm) 

1,100 Cu, 210 Pb, and 400 Zn (Kilburn and others, 1994). Although certain facets cf the 

sorption process remain open to question, it is believed that the capacity of metal 

hydroxides to effectively scavenge dissolved metals is directly linked to the net surfroe 

charge of the hydroxide, which in turn is a function of pH. As a rule, metal hydroxides 

sustain a net positive charge in highly acidic solutions, and become progressively more 

negatively charged (by losing protons) as the pH approaches neutral values. Sorption of

11
cations therefore intensifies as pH increases, with bonding to solid phase hydroxides 

occurring over a narrow pH range (adsorption or pH edge) that is unique to individual 

metal species (Smith and Macalady, 1991). In addition to pH, other variables affecting this 

metal-partitioning reaction include the variety and abundance of metal hydroxide soMs, 

the presence of competing ligands (such as dissolved organic carbon and sulfate), and the 

concentration and speciation of dissolved metals.

Interpretation and Discussion

The weathering of pyrite and other sulfides within the Holden mine is incessrnt, 

regardless of season. Oxygenated groundwater flowing along easily accessed conduits 

within the underground workings (e.g. shafts, drifts, and crosscuts) or as confined seepage 

in faults, fractures, and other permeable zones, aggressively oxidizes and dissolves polite 

and other sulfides, liberating Fe2+, trace metals (such as Zn, Cu, and Cd) and high 

concentrations of acid (H4") to the migrating waters. The ensuing solutions are corrosive 

and readily attack not only sulfides but,the enclosing wallrock as well, prompting acid 

reactions with, and total or partial dissolution of the more resistate rock-forming (sil^ate) 

minerals (releasing into solution Al and the alkali and alkaline earth metals including Na, 

K, Ca, and Mg). In response to various acid-consuming processes such as the 

wallrock-acid reaction described above and/or dilution by transient mine and ground 

waters, the pH of the oxidizing solutions rises, resulting in the precipitation of Fe and Al 

hydroxides (possibly in concert with relatively insoluble sulfate phases such as anglerUe) 

and sorption or coprecipitation of receptive trace metals (depending on pH). Because the 

hydrolysis of Fe3+ occurs at a much lower pH than Al, most of the dissolved Fe 

precipitates prior to passing through the adit portal and explains the relatively low acueous 

concentrations of Fe and corresponding scarcity of Fe hydroxide material found in the 

surface portal effluent.

It is apparent that mine water chemistry at the Holden site is greatly affected by the 

seasonal availability of water. As mentioned previously, the lowest pH and highest 

dissolved metal concentrations (as well as total dissolved mass) are associated with the 

spring runoff. Although an excess of water in the spring certainly enhances oxidation 

processes, these complex reactions normally take place at rates much too slow to account 

for the rapidity at which added metal and acid loadings materialize in the spring portal 

discharge. The quick response (metal and acid loadings) to spring hydrologic conditions 

coupled with seasonal variation in Zn/Cu ratios (Alpers and others, 1994; Kilburn and 

Sutley, 1997) strongly suggest the dissolution and flushing of soluble metal salts. 

By-products of sulfide oxidation, metal salts or sulfates represent transitory storage of 

acid and metals in the solid phase, and their cycles of dissolution and precipitation is 

considered a primary influence on the seasonal fluctuations in mine water chemistry 

encountered at many pyrite-rich mining localities including other massive sulfide deposits 

such as Iron Mountain, California (Alpers, 1994) and genetically unrelated orebodies such 

as the Summitville, Colorado acid sulfate epithermal deposit (King, 1995). It is believed 

that these secondary minerals may accumulate in Holden's underground workings as 

saturated and supersaturated mine waters recede and evaporate during periods of dry 

weather (e.g. late summer and fall months at Holden). If this is the case, the highly soluble

12
efflorescent minerals would readily dissolve during the heavy spring runoff witnessed at 

Holden, resulting in the abrupt rise in dissolved metals and corresponding drop in pF that 

characterize the spring portal discharge. As water levels invariably ebb following the initial 

spring melt, acid and metal-loading would diminish as flushing subsides and sulfate 

precipitation commences in response to more temperate or arid conditions. This seasonal 

process of sulfate growth probably continues into the fall months or until reasonably 

steady flow conditions are achieved, at which time dissolved metal concentrations (ir the 

portal drainage) stabilize and largely reflect direct sulfide oxidation. The salts would 

presumably remain intact until the next high-flow hydrologic event (probably the spring 

thaw). Fluctuations in this postulated hydrogeochemical cycle could result from summer 

storm events and abnormally mild weather conditions in winter.

Obviously, the rapid change in spring portal water chemistry is a multidimens: onal 

phenomenon and related to processes other than the simple dissolution of soluble 

secondary minerals. However, available data is of little help in defining these interactions, 

and the nature (and impact) of these controls remain largely conjectural. For instance, it is 

reasonable to assume (although evidence is lacking) that vestiges of the spring flushing 

event may persist in the mine in the form of isolated pools or ponds that develop in 

low-lying areas (unfilled stopes and drifts ?) or as saturated zones of interstitial water 

within the surrounding country rock, or both. During the low-flow, relatively dry period, 

the hypothesized seasonal reservoirs and pore solutions would become increasingly 

degraded as evaporation and prolonged contact with the adjacent country rock (and 

sulfides) concentrate and enhance acid and dissolved metal concentrations. These acidic, 

metalliferous solutions may then be flushed or swept out the portal as mine flooding 

commences the following spring.

At the time of the spring runoff (normally in May), the portal discharge is further 

characterized by a significant reduction in dissolved base-metal concentrations (Cd, Cu, 

and Zn) between the mine entrance and Railroad Creek. This coincides with an equally 

significant drop in the total dissolved mass of these constituents along the flow path. On 

the other hand, in July and September, base-metal concentrations remain reasonably 

constant along the length of the portal drainage despite experiencing a substantial 

decrease in total dissolved mass. It is believed that the collective metal depletion (mass 

and concentration) that accompanies the May discharge stems in large part from the 

diluting effects of the surrounding spring snowmelt together with sorption of dissolved 

metals (particularly Cu) onto solid phase oxyhydroxides. This presumption is based on 

field measurements, analytical data, and site-specific observations compiled by Dames & 

Moore and the USGS. During the May, 1997 field season, numerous rills, rivulets, ard 

sheets of surface runoff that are not normally present in mid-summer and fall were 

observed entering the portal drainage at many localities between the mine entrance ard 

Railroad Creek. This visual influx of presumably dilute surface water is consistent with 

field measurements taken by Dames & Moore, which indicate that the portal drainage 

increases in volume by about 23 % between the mine (flow rate of 2.63 ft3/s) and the area 

just above the confluence with Railroad Creek (flow rate of 3.42 ft3/s) (Dames and 

Moore, preliminary and unpublished data, 1998). In addition to dilution, sorption 

processes appear to play an active role in tempering dissolved base-metal levels (both 

concentration and mass). This metal partitioning reaction is most evident when

13
considering Cu, which declines about 60 % in concentration and 47 % in mass between 

the mine and Railroad Creek. This is not surprising, since Cu is preferentially sorbed Vy 

metal hydroxides within the limited pH range (4.8-4.9) of the spring portal drainage. 

Conversely, Zn and Cd are highly mobile, and would be expected to resist sorption at this 

pH, yet their total dissolved mass declines by 23 % and 16 %, respectively; suggesting 

some interaction and bonding with solid phase material. Regarding the mid-summer (July) 

and fall (September) portal effluent, water analysis outwardly reflects a rather conservative 

system (nonreacting), with dissolved base-metal concentrations remaining remarkably 

stable between the portal and Railroad Creek. This, however, is somewhat misleading. At 

this time of year, flow between the mine entrance and Railroad Creek is in a losing 

posture, (declining by roughly 26 % in July and 29 % in September), so that the total 

mass of dissolved base-metals entering Railroad Creek is actually much less than the 

dissolved load that initially exits the portal. Moreover, the dominant mode of mass 

reduction appears different in July than in September. In mid-summer (July), the total mass 

of dissolved Cu, Zn, and Cd declines about 27 %, 28 %, and 26 %, respectively. This 

compares favorably with the decrease in flow (26 %) between the portal (0.42 ft3/s) and 

Railroad Creek (0.3 Ift3/s) and suggests the loss of metals along the flow path can largely 

be attributed to physical processes such as infiltration of portal water into underlying soil 

horizons, rather than chemical partitioning reactions. In contrast, mass balance 

calculations for the fall discharge (September) indicate that the total mass of dissolved Cu, 

Zn, and Cd decline along the flow path by roughly 74 %, 35 %, and 29 %, respectively. 

With measured flow rates between the portal (0.21ft3/s) and Railroad Creek (0.15ft3/s) 

dropping by only 29 %, a good portion of this mass reduction (especially Cu) is probably 

achieved via sorption onto various solids in contact with the portal discharge or suspended 

in the water column.

Mill Site, Waste Dumps, and Lagoon Area

Nowhere at the Holden site is visual evidence of spring runoff more conspicuous 

than the area above and generally west of Tailings Pile 1 (the western most tailings 

impoundment), where relatively heavy surface discharge from the mill is promptly 

channeled into a holding pond (lagoon area) below and west of the abandoned facility 

(figure 2). This seasonal outflow is in sharp contrast to mid-summer and fall levels, when 

mill effluent is generally limited to small seeps and trickles. Likewise, the holding pond 

(lagoon area) is largely dissipated by mid-summer and completely dry by autumn. The 

onset of high seasonal runoff is also marked by relatively heavy discharge associated with 

the waste rock piles located to the east and west of the mill facility (figure 2). By 

midsummer, however, surface runoff identified with the waste pile east of the mill is totally 

absent, while seepage linked with the western waste pile is greatly diminished (and 

virtually nonexistent by early autumn). According to Dames & Moore, the seasonal 

(spring) inundation of water that saturates the lower mill area and passes through the 

waste rock piles is largely derived from upgradient snowmelt that proceeds downslop^ as 

surface run-on and/or shallow groundwater in soil and reworked till units (a 

heterogeneous mixture of silty gravel, sand, and gravel)

14
Although intense sulfide weathering associated with residual ore material in the 

mill is ultimately responsible for much of the abandoned facility's acidic, metalliferous 

discharge, the flushing of soluble mineral salts is considered the immediate or primary 

control during the spring runoff and other episodes of seasonal precipitation. Chemical 

manifestations of this seasonal phenomenon can be rather striking as evidenced by the 

compositions of effluent sampled from within the recesses of the mill. These waters 

typically involve a complex suite of dissolved solids that are present in extremely high 

concentrations measured by the USGS of up to (in |ig/L) 5.7 Ag, 760,000 Al, 4,80C Cd, 

1,400 Co, 650,000 Cu, >500,000 Fe, >100,000 Mg, 1,100 Ni, 600 U, and 610,000 Zn 

(Kilburn and Sutley, 1996; Kilburn and Sutley, 1997). However, this discharge is generally 

in the form of small seeps or sulfate drippings that are inevitably diluted by the spring melt 

or evaporate during more arid conditions, leaving behind a metal-rich sulfate residue. Of 

more immediate concern is the base-metal rich water that actually exits the mill faciPty in 

the spring and early summer, either as channeled surface runoff (to the lagoon area) or as 

subsurface flows of indeterminate volume. The exodus of the metalliferous drainage from 

the mill (including the groundwater) is/preceded by continuous mixing with more diffuse 

flows which attenuate the dissolved metal load, raise the pH, and promote the 

precipitation of Fe and Al hydroxides and sorption of responsive metal species (the lower 

levels of the mill are marked by thick accumulations of flocculated metal hydroxide 

material). The greatly tempered surface discharge may subsequently enter Railroad Creek 

via the lagoon, either as overland flow or low volume seepage. The flowpath of the 

corresponding groundwater is more uncertain. It is likely that as this subsurface water 

moves downward and laterally away from the mill area, it may emerge as Fe-poor, Cu-Znrich seepage along the banks of Railroad Creek and/or pass beneath the western per:")hery 

of Tailings Pile 1, mixing with and enhancing the base-metal content of Fe-rich tailirgs 

solutions. In the latter instance, the migrating waters may move upward in response to 

drying conditions and resultant capillary forces to evaporate on the surface, precipitating a 

host of secondary sulfate minerals (including Fe- Cu- and Zn- phases) that have been 

identified historically near the confluence of the Copper Creek diversion and Railroad 

Creek (Kilburn and others, 1994; Kilburn and others, 1995a,b).

The lagoon below the mill (figure 2) is a seasonal body of water characterized by 

an abundance of white-tan, metal hydroxide precipitates (probably Al) together with high 

levels of Cd, Cu, and Zn. This ephemeral holding pond (which is largely a spring and early 

summer entity) is fed by two discrete sources of weakly acidic, base-metal rich effluent, 

including: (1) the above referenced surface runoff from the mill; and (2) surface discharge 

and seepage springs associated with the large waste pile west of the mill structure (this 

surface discharge merges with the channeled mill flow prior entering the lagoon). 

Significant flow from these tributary effluents is by and large a spring and early summer 

occurrence, with fluctuations in the size or volume of the lagoon generally equated to their 

discharge (percolation and evaporation rates become more important as recharging events 

subside). As noted above, the lagoon may serve as a short-term reservoir for migrating, 

base-metal rich water known to enter Railroad Creek, either as seepage or small surface 

flows. Regarding the former, it is speculated that subsurface drainage from the lagoon may 

flow some distance down drainage before eventually surfacing as constituents of 

intermittent, Fe-rich seeps near the base of Tailings Pile 1. A potential artery for this

15
subsurface flow is the old Railroad Creek channel that underlies a portion the lagoon area. 

The channel, which was abandoned at the time Railroad Creek was diverted to the ncrth 

(before the mine was operational), extends eastward from the lagoon and passes beneath 

the northern length of Tailings Pile 1 (Dames & Moore, preliminary and unpublished data, 

1998).

The second waste rock pile is located approximately 100 m east of the abandoned 

mill, above the western half of Tailings Pile 1 (figure 2). During the spring thaw, weakly 

acidic, Fe-poor, base-metal rich effluent which surfaces near its base, flows west (about 70 

m) along the break in slope, before being redirected and channeled across the western brim 

of Tailings Pile 1 and into Railroad Creek via the Copper Creek diversion. As the effl lent, 

which has historically appeared milky-white owing to the precipitation of amorphous 

solids (probably Al-hydroxides; Kilburn and Sutley, 1997), advances downward toward 

Railroad Creek, base-metal concentrations are substantially moderated by natural physical 

(dilution) and chemical (precipitation and sorption) processes. Evidence of this attenuation 

is obvious when reviewing water quality data gathered by Dames & Moore in the sprng 

(May) of 1997. Dissolved base-metal concentrations decrease from (in jig/L) 87.8 Cd 

7,880 Cu, and 11,200 Zn below the waste pile to (in ng/L) 50.1 Cd, 4,180 Cu, and 6,170 

Zn near the juncture with the Copper Creek diversion. However, the total mass of 

dissolved base-metals increases dramatically (roughly 60 %) along this passage; a 

phenomenon which corresponds with an equally prominent gain in discharge volume 

(about 79 %) between the waste pile (flow rate of 2.0 x 10"2 ft3/s) and the Copper Creek 

diversion (flow rate of 9.47 x 10"2 ft3/s) (Dames & Moore, preliminary and unpublished 

data, 1998). Apparently this mutual increase in flow rate and total dissolved mass is 

largely dependent on numerous seeps and overland flows observed entering the drainage 

along the break in slope, above the tailings.

The cyclic retention and flushing of heavy metals from mine rock dumps is weN 

chronicled from mine sites around the world (Lin and Herbert, 1997), and is no doubt the 

fundamental process contributing to the seasonal, base metal-rich discharge associated 

with the Holden waste piles. In general, the weathering of sulfides and other minerals in 

the leached zone of both waste dumps has resulted in the movement of metals downward 

to a zone of accumulation near the basement footing or in the underlying soils, where the 

metals are temporarily held in more stable secondary mineral phases. The resultant so'uble 

minerals are likely candidates for dissolution and hydraulic flushing as upslope water 

infiltrates the waste piles during the course of the spring melt or episodic storm events, 

releasing base-metals and other elements to solution.

Honeymoon Heights drainage

The Honeymoon Heights area is located south and west of the mill facility, SOTIC 

150 m in elevation above Railroad Creek (figure 2). This former prospect consists largely 

of exploratory pits and portals, scattered rock piles, and miscellaneous refuse customarily 

associated with historic mining operations. During the spring, the area is marked by 

intermittent, often coalescing small surface flows derived from upslope meteoric sources. 

Much of this seasonal surface runoff may experience some degree of metal loading from 

interaction with mineralized rock or its soluble by-products before discharging into

16
Railroad Creek as groundwater or intermittent seeps. One seep, which surfaces belov 

Honeymoon Heights (figure 2), is of particular interest and represents a major, short-term, 

source of base-metals to Railroad Creek during the spring (the drainage is commonly dry 

for much of the year). Preliminary field and analytical data gathered by Dames & Moore" 

indicate that as much as (in kg/day) 0.03 Cd, 5.0 Cu, and 4.0 Zn may enter Railroad Creek 

from this drainage during specific cycles of the spring runoff (Dames & Moore, 

preliminary and unpublished data, 1998). The origin of this metal-rich discharge, however, 

remains problematic. Perhaps, because of its location, the seep may simply be a seasonal 

manifestation of upgradient prospects in the Honeymoon Heights area. However, in order 

for the drainage to reach Railroad Creek along this flow path, it would of necessity, pass 

through or over roughly 150 m of shallow, moist mountain soil, where prevailing oxidizing 

and buffering conditions would be expected to reduce dissolved metal concentrations 

significantly. The relatively high Al and base-metal content of the waters would seem to 

preclude this passage and suggests a more local source, such as mineralized avalanche 

talus that may have accumulated in the lower reaches of the drainage (the flow path 

closely follows an avalanche track that can be traced through and above the Honeymoon 

Heights prospects) or even a breach in "the underground workings of the mine itself.

East Area

The East Area is dominated by three massive tailings piles (numbered 1, 2, and 3 

from west to east) that altogether encompass close to 90 acres east of the abandoned mill 

along the south bank of Railroad Creek (figure 2). Collectively, the piles contain about 7.7 

million metric tons of tailings material capable of oxidizing at a rate estimated to be 200 

times or more greater than undisturbed or unmined massive sulfide deposits (Boyle, 1994). 

Because this benefication refuse lies adjacent to Railroad Creek, the risk of disseminating 

both solid and liquid contaminants is greatly enhanced.

At the surface, the mill tailings are weathered a distinct yellow-ocher color ard 

consist primarily of discarded gangue material (quartz, feldspar, and ferromagnesian 

silicates) and lesser amounts of secondary Fe-hydroxides (goethite) and hydroxysulfates 

(jarosite). The conspicuous absence of ore and ore-related minerals such as chalcopyrite 

and pyrite is not surprising, and is merely an indication of near surface oxidizing processes. 

Another manifestation of surface weathering, which may pique mining interests and 

facilitate remediation efforts, is the widespread enrichment of Au in the oxidized tailirgs 

(ranging from 0.43 to 1.7 ppm) (Kilburn and Sutley, 1996). As a result of site reclamation 

activities initiated and financed by the USFS (1989-1991), the tailings piles are currently 

capped by a veneer of granitic gravel to minimize persistent wind-blown contamination 

and a string of nurseries to propagate and restore native vegetation. In addition, the 

overall tailings impoundment was confined by an extensive network of basal riprap to 

guard against creek "undercutting" and forestall the gravitational sliding of unstable mill 

waste into Railroad Creek.

The East Area is further typified by the occurrence of acidic, Fe-rich seeps that 

surface intermittently near the base of the tailings. This seepage is invariably associated 

with substantial accumulations of ferric oxide precipitates, either as a thick coating on 

basal tailings material or as ferricrete conglomerates (a ferric oxide or hydroxide cemented

17
conglomerate composed of tailings material, gravel, and river rock) (Kilburn and Sutley, 

1996). More importantly, the seeps and difliise groundwater flow from beneath the 

tailings are considered the major source of total and dissolved Fe to Railroad Creek 

throughout the year (Dames and Moore, preliminary and unpublished data, 1998). 

Because of the low volume, intermittent nature of the tailings seeps, identification of nany 

sites for seasonal resampling is difficult, if not impossible. Accordingly, flow rates and 

interdependent mass balance calculations were not considered for the following 

discussion. However, the collective water quality data compiled by Dames & Moore and 

the USGS appears sufficient to characterize the discharge and address potential seasonal 

controls. It is assumed (like elsewhere at Holden) that the total mass of dissolved solids is 

greatest during the spring runoff, and steadily declines as water levels progressively etb in 

response to more arid conditions in the summer and fall months.

Fe-dominant Tailings Seepage

Nearly all of the acidic, Fe-dominant seeps emerging from tailings piles 1-3 surface 

adjacent to Railroad Creek, although some intermittent flows can be found along the 

eastern periphery of Tailings Pile 3. The tailings effluent is probably derived from a 

composite of surface water and groundwater sources that are part of a hydrologic regime 

much too complex to detail at length in this report. In brief, however, surface water can 

infiltrate the tailings as direct precipitation or as run-on from upgradient sources south of 

the tailings impoundment's. This surface water may eventually migrate downward to a 

zone of accumulation near the base of the tailings. Groundwater, also originating from 

upslope sources is believed to pass beneath the tailings through alluvium and reworked till 

units (Dames and Moore, preliminary and unpublished data, 1998). To what degree th?<se 

discrete water sources interact is unknown, although some level of mixing is likely. 

Typical of the Holden site, penetration of surface water and groundwater into the tailings 

is highly seasonal, with the greatest influx generally associated with the spring runoff and 

episodic storm events. This cycle is reflected in the abundance and volume of tailings 

seepage, which are most prominent in the spring.

In general, the tailings seeps are acidic, Fe-rich, high-ionic strength (sum of cat: ons 

and anions) solutions marked by a wide range in elemental compositions. During the 

lengthy 1997 field season (May to October), tailings seeps sampled by Dames & Moore 

contained dissolved metal levels ranging from (in (Xg/L) 3,920 - 115,000 Al, 1.8 - 40.3 Cd, 

90 - 1,280 Cu, 8,670 - 1,260,000 Fe, and 232 - 5,700 Zn (Dames & Moore, preliminary 

and unpublished data, 1998) which is consistent with data compiled from earlier USGf 

investigations (Kilburn and Sutley, 1996, 1997; Kilburn and others, this report). 

Recognizing a seasonal bias in seepage chemistry, however, proved more difficult than 

first envisioned because of: (1) the transient nature of the discharge and the complicated 

flow patterns that accompany the spring melt; (2) the chemical and mineralogical 

heterogeneity of the tailings; and (3) the lack of definitive flow rate data. In any event, a 

perusal of the seepage data suggest that base-metal concentrations steadily diminish from 

spring to fall, whereas Fe and Al concentrations appear to increase from spring to 

mid-summer, then experience a decline by early fall. This seasonal variation in effluent 

chemistry can probably be traced, in large part, to the diluting and flushing effects of tH

18
spring runoff. In addition, because the elemental suites of reference (Cu-Cd-Zn vs. Fe-Al) 

seemingly follow discrete seasonal trends, different sources of dissolved metals are 

suspected. Logical candidates include weathering primary minerals (both sulfide and 

silicate) and their soluble secondary by-products. Concerning the latter, the dissolution 

and hydraulic flushing of unstable secondary minerals is viewed as the overriding factor 

leading to the base-metal enrichment characteristic of the spring and early summer taTngs 

discharge. Field and laboratory evidence strongly suggest that base-metals are derived not 

only from readily soluble material within the tailings, but also from upslope point sources 

such as the waste rock piles and the mill area (Kilburn and Sutley, 1996, 1997). Although 

some of this upslope water may infiltrate the tailings via surface run-on, the greater body 

of contaminated water probably enters the tailings as subsurface flows; i.e. the buried 

Railroad Creek channel. Following the initial spring runoff, the effects of flushing quickly 

diminish as the influx of extraneous, base-metal rich water abates and original mass of 

soluble minerals interspersed along the different flow paths is depleted. As a consequence, 

subsequent flows or short-term spikes of water through the tailings carry progressively 

lower dissolved base-metal concentrations. This pattern continues until stable flow 

conditions are attained in late fall or winter, when seepage compositions would be 

expected to remain fairly uniform until the next major flushing event (the following spring 

?). Regarding the Fe-Al suite, the oxidation of pyrite and resultant leaching of Al and 

other metals and elements (e.g., Mg, Na, and the rare earths) from largely silicate hosts 

within the tailings is a continuous process throughout the year, with weathering rates 

largely dependent on the seasonal availability of oxygenated groundwater and the height 

or position of the water table. Other parameters less (or not) subject to seasonal variability 

include the diffusion rate of atmospheric O2 into the tailings, bacterial activity, sulfide and 

gangue mineralogy, mineral grain size, porosity and permeability, and the geometry and 

structural characteristics of the tailings (Boyle, 1994). During the spring inundation, 

however, dilution rather than direct oxidation appears to be the predominant process 

controlling dissolved Fe and Al concentrations, and the metals are probably attenuated by 

the heavy flow. As flooding subsides, these metal concentrations rise in accordance, 

augmented by additional Fe and Al loadings resulting from intensified pyrite oxidation and 

reciprocal silicate weathering (owing to the retention of excess water associated with the 

runoff event). As access to oxygenated groundwater becomes limited in late summer, 

pyrite oxidation and metal leaching diminish and Fe and Al concentrations decline 

proportionately until sustained base flow conditions resume in the fall, at which time 

seepage chemistry most likely stabilizes.

Clearly, water draining or in contact with the tailings provides and excellent 

avenue for hydrodynamic metals dispersion. However, the fundamental chemistry of the 

effluent remains somewhat puzzling. The primary controls for producing acidic, metal-rich 

drainage are clearly in place, with the mining and milling of massive sulfide ore affording 

oxygen-rich water easy access to tremendous volumes of fine-grained, pyrite rich tailings 

with little inherent acid-buffering capacity. Under these circumstances, the highly acidH 

Fe-dominant tailings seepage identified by the USGS and Dames & Moore was not 

unexpected, and certainly compatible with a pyrite dominated system. However, the 

concentrations of accompanying base-metals, although relatively high by many standards, 

is a departure from the extreme levels frequently encountered elsewhere in waters derved

19
from weathering VMS mines and deposits. This may be related, in part, to yet unidentified 

processes such as the formation of local pH or redox boundaries (within the tailings) that 

can effectively restrict the mobility of dissolved metals (Blowes and others, 1991). A more 

likely scenario simply involves a lack of significant chalcopyrite and sphalerite in the 

tailings.

SUMMARY

Inactive or abandoned mine sites associated with volcanogenic massive sulfide 

deposits have yielded some of the most acidic, metalliferous mine drainage on record, and 

are of particular environmental concern. Accordingly, the U. S. Geological Survey 

conducted a series of geochemical surveys at the Holden mine, a relatively low-grade, 

Kuroko-type VMS deposit in order to assess the character, origin, and extent of 

contaminated waters derived from this former producer of base-and precious-metal ore. 

Seasonal variation in mine water chemistry were also addressed. Findings from these 

studies were augmented by compatible, but preliminary, water quality data collected e* the 

mine by Dames & Moore on behalf of Alumet Inc. Collectively, these investigations 

(planned and administered independently) disclosed a dynamic and complex hydrolog: c 

regime, typified by a wide-range in mine effluent compositions that normally experien~<e 

significant seasonal fluctuations in chemical composition and magnitude of flow. For 

simplicity, the mine discharge has been broadly categorized into two discrete groups Hsed 

on chemical congruity and general proximity as follows: (1) acidic to strongly acidic, 

Fe-rich seeps that surface intermittently at or near the base of the tailings; and (2) weakly 

acidic to near neutral, base-metal rich (Cd, Cu, and Zn) water draining the mine, mine 

workings, and various waste piles and prospects located for the most part west of the 

tailings.

The elemental suites and concentrations (environmental signature) that 

characterize Holden's mine drainage is contingent on many natural controls and processes 

including (but not limited to) ore and gangue mineralogy, host rock lithology, geochemical 

interactions, and climate. These natural controls are enhanced and modified by certain 

anthropogenic factors which are largely a function of mineral development such as mining 

and ore processing methods. The mine discharge is further characterized by a marked 

seasonal variation in mine water chemistry. As a rule, the lowest pH and highest dissolved 

metal concentrations (and total dissolved mass) coincide with high flow conditions 

associated with the spring snowmelt. As conditions stabilize, and water flow increasingly 

subsides through the summer and fall, the pH levels gradually rise, whereas constituent 

dissolved metals decline perceptibly. This change in mine water chemistry is largely 

attributed to the dissolution and hydraulic flushing of soluble metal salts in the spring and 

their precipitation from saturated and supersaturated solutions in the summer and fall.

20
ACKNOWLEDGMENTS

The authors wish to thank Alumet Inc. for their cooperation in preparing this 

report. The preliminary and unpublished data they provided was essential in describing and 

characterizing mine drainage conditions at the Holden site. We would also like to express 

our gratitude to Rik Langendoen of Dames & Moore and Dave Jackson of Jackson and 

Associates, who were most helpful in this endeavor. We also appreciate the efforts of 

Keith Anderson of the USFS who provided timely logistical support and informative 

counsel.

21
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25
Table 1. Analytical data for untreated water samples collected at the Holden mine, September 1996. Temperature, pH ar 

conductivity are field measurements; anion analysis by ion chromatography

Sample #

HM700

HM702

HM703

HM704

HM705

HM706

HM707

HM708

HM709

HM710

HM711

HM712

HM713

HM714

HM715

HM716

HM717

HM718

HM719

HM720

HM721

HM722

HM723

HM724

HM725

HM726

HM727

HM728

HM729

HM730

Source

RR Creek

Portal Effluent

Portal Effluent

Portal Effluent

RR Creek

RR Creek

RR Creek

RR Creek

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Copper Creek

Copper Creek

Temp C

7

8

9

9

7

9

7

7.5

7

6

6

6

6

6

7

5

5

6

4

5

5

5

5

11

14

15

3

3

2

2

pH

6.23

6.22

6.25

6.52

6.99

6.74

6.86

6.81

6.93

3.28

3.64

2.97

3.38

3.44

3.f4

5.45

3.46

3.12

3.21

3.35

3.45

6.11

3.27

3.12

3.06

3.05

6.09

3.86

6.26

6.39

Conductivity

uS/cm

49

797

797

797

34

510

33

53

36

5120

5200

4900

5060

5310

5790

364

3640

4190

3280

4630

3390

58

4810

3060

3110

3140

72

4640

37

37

Sulfate

mg/L

12

400

400

400

4

220

4

10

4

4730

4040

3900

4000

4530

4610

66

2000

2270

1560

2670

1610

16

2980

1360

1080

1360

24

2530

4

4

Fluoride

mg/L

<0.1

0.4

0.4

0.5

<0.1

0.3

<0.1

<0.1

<0.1

3.6

2.2

3.9

2.2

2.1

4.2

<0.1

1.4

<0.1

<0.1

2.4

<0.1

<0.1

1.5

<0.1

<0.1

<0.1

<0.1

0.8

<0.1

<0.1

ChlorHe

mg/L

0.4

8.3

7.3

7.2

0.4

4.5

0.4

0.5

0.4

12

10

5.8

7.2

8.3

9.1

0.8

3

2.4

4.8

7.3

1.8

0.5

4.3

2.7

1

5.3

0.4

1.5

0.1

0.2

26
Table 2. ICP-AES analysis of filtered and acidified water samples collected at the Holden mine, Sept 1936

Sample #

Source

Almg/L

Bug/L

Baug/L

Beug/L

Camg/L

Cdug/L

Coug/L

Crug/L

Cuug/L

Femg/L

Kmg/L

Uug/L

Mgmg/L

Mnug/L

Moug/L

Namg/L

Niug/L

Pug/L

Pbug/L

Simg/L

Srug/L

Tiug/L

Vug/L

Znug/L

Sampled

Source

Almg/L

Bug/L

Baug/L

Beug/L

Camg/L

Cdug/L

Coug/L

Crug/L

Cuug/L

Femg/L

Kmg/L

Uug/L

Mgmg/L

Mnug/L

Moug/L

Namg/L

Niug/L

Pug/L

Pbug/L

Simg/L

Srug/L

Tiug/L

Vug/L

Znug/L

HM700

RR Creek

0.018

13

5.4

<10

7.3

<10

<10

<10

<10

2.5

<1

<10

1

36

<20

1.2

<10

<50

<50

3.2

26

<50

<10

39

HM708

RR Creek

O.015

20

5.2

<10

8.5

<10

<10

<10

<10

<0.1

<1

<10

<1

<10

<20

1.5

<10

<50

<50

3.2

31

<50

<10

60

HM702

Portal Effluent

0.044

250

10

<10

160

<10

<10

<10

62

0.28

6.2

35

11

420

<20

27

<10

<50

<50

7.9

550

<50

<10

3600

HM 709

RR Creek

0.013

16

5.1

<10

6.2

<10

<10

<10

<10

<0.1

<1

<10

<1

<10

<20

1.1

<10

<50

<50

3.1

23

<50

<10

11

HM703

Portal Effluent

0.043

250

11

<10

160

<10

<10

<10

23

<0.1

6.4

37

11

400

<20

2 

<10

<50

<50

7.7

580

<50

<10

3300

HM710

Tailings Seep

54

<10

5.4

<10

300

50

110

<10

<10

1600

15

48

180

13000

<20

28

<10

<50

73

26

750

<50

43

7800

HM704

Portal Effluent

0.034

240

11

<10

150

<10

<10

<10

12

<0.1

6.3

37

11

370

<20

27

<10

<50

<50

6.7

560

<50

<10

2900

HM711

Tailings Seep

36

<10

11

<10

260

26

100

<10 '

<10

1500

15

38

150

11000

<20

23

<10

<50

<50

19

680

<50

35

5000

HM705

RR Creek

0.013

16

5.2

<10

6

<10

<10

<10

<10

<0.1

<1

<10

<1

<10

<20

<1

<10

<50

<50

3.2

22

<50

<10

<10

HM712

Tailings Seep

96

<10

<5

<10

250

21

96

<10

180

1300

9.2

110

140

9800

<20

24

<10

<50

<50

44

610

<50

50

8300

HM706

RR Creek

0.023

170

8.7

<10

110

<10

<10

<10

11

<0.1

4.4

24

7.7

270

<20

18

<10

<50

<50

5.8

380

<50

<10

2200

HM713

Tailings Seep

23

<10

8.9

<10

340

23

110

<10

<10

1400

19

41

200

15000

<20

22

10

<50

<50

24

770

<50

30

6000

HM707

RR Creek

0.011

16

5.1

<10

5.8

<10

<10

<10

<10

<0.1

<1

<10

<1

<10

<20

<1

<10

<50

<50

3

21

<50

<10

<10

HM714

Tailings Seep

20

<10

<5

<10

340

3^

121

<10

<10

1600

if

3?

210

16000

<20

2:

11

<50

<50

2*

800

<31

32

7300

27
Table 2. ICP-AES analysis of filtered and acidified water samples collected at the Holden mine, Sept 1996

Sample #

Source

Almg/L

Bug/L

Baug/L

Beug/L

Camg/L

Cdug/L

Coug/L

Crug/L

Cuug/L

Femg/L

Kmg/L

Liug/L

Mgmg/L

Mnug/L

Moug/L

Namg/L

Niug/L

Pug/L

Pbug/L

Simg/L

Srug/L

Tiug/L

Vug/L

Znug/L

Sample #

Source

Almg/L

Bug/L

Baug/L

Beug/L

Camg/L

Cdug/L

Coug/L

Crug/L

Cuug/L

Femg/L

Kmg/L

Liug/L

Mgmg/L

Mnug/L

Moug/L

Namg/L

Niug/L

Pug/L

Pbug/L

Simg/L

Srug/L

Tiug/L

Vug/L

Znug/L

HM715

Tailings Seep

110

<10

16

<10

470

43

160

<10

450

1500

26

110

270

19000

<20

37

54

<50

56

45

890

<50

40

8700

HM722

RR Creek

0.036

12

5.5

<10

8.7

<10

<10

<10

<10

3.4

<1

<10

1.3

40

<20

1

<10

<50

<50

3.4

28

<50

<10

54

HM716

RR Creek

0.053

<10

5.9

<10

16

<10

<10

<10

<10

43

1.2

<10

4.7

200

<20

1.7

<10

<50

<50

3.7

42

<50

<10

330

HM723

Tailings Seep

88

<10

11

<10

300

18

75

<10

110

800

32

110

130

9100

<20

21

<10

<50

<50

27

890

<50

18

8000

HM717

Tailings Seep

56

<10

19

<10

380

11

33

<10

1300

290

23

58

100

5000

<20

16

K)

<50

<50

35

970

<50

<10

3700

HM724

Tailings Seep

17

28

28

<10

310

<10

30

<10

280

210

28

31

74

5200

<20

13

<10

<50

<50

23

730

<50

<10

950

HM718

Tailings Seep

19

<10

<5

<10

410

<10

35

<10

120

430

28

45

130

6700

<20

18

<10

<50

<50

22

1200

<50

<10

1300

HM725

Tailings Seep

12

22

32

<10

330

<10

29

<10

210

210

27

24

74

5200

<20

12

<10

<50

<50

20

670

<50

<10

780

HM719

Tailings Seep

13

31

5

<10

350

<10

29

<10

57

230

27

52

100

5200

<20

16

<10

<50

<50

20

940

<50

<10

510

HM726

Tailings Seep

11

32

48

<10

300

<10

27

<10

150

210

28

34

73

5200

<20

13

<10

<50

<50

20

740

<50

<10

960

HM720

Tailings Seep

59

<10

7.1

<10

390

14

78

<10

630

740

28

81

140

8000

<20

19

<10

<50

<50

23

890

<50

13

2400

HM727

RR Creek

0.04

14

6

<10

10

<10

<10

<10

<10

5

<1

<10

1.7

66

<20

1.4

<10

<50

<50

3.5

33

<50

<10

55

HM721

Tailings Seep

19

<10

20

<10

330

<10

34

<10

.73

290

27

33

92

5000

<20

14

<10

<50

<50

18

850

<50

<10

760

HM 728

Tailings Seep

51

<10

41

<10

310

24

73

<10

160

880

32

34

100

7900

<20

18

<10

<50

<50

16

760

<50

13

4100

28
Sample 

Source

Almg/L

Bug/L

Baug/L

Beug/L

Camg/L

Cdug/L

Coug/L

Crug/L

Cuug/L

Femg/L

Kmg/L

Liug/L

Mgmg/L

Mnug/L

Moug/L

Namg/L

Niug/L

Pug/L

Pbug/L

Simg/L

Srug/L

Tiug/L

Vug/L

Znug/L

Table 2. ICP-AES analysis of filtered and acidified water samples collected at the Holden mine, Sept. 1996

HM 729 HM 730 

Copper Creek Copper Creek

0.023

<10

6.7

<10

6

<20

1.1

<10

<50

<50

3.8

20

<50

<0.01

<10

6.5

<10

6

<10 

<10 

<10 

<10

0.14

<20

1.1

<10

<50

<50

3.7

20

<50

29
Sample # Source Ag

Table 3. ICP-MS analysis of filtered and acidified water samples collected at the Holden mine, Sep

Elemental concentrations expressed as ug/L

As Au Ba Be Bi Cd Ce Co Cr Cs Cu Dy 

HM700

HM702

HM703

HM704

HM705

HM706

HM707

HM708

HM709

HM710

HM711

HM712

HM713

HM714

HM715

U) HM716

° HM717

HM718

HM719

HM720

HM721

HM722

HM723

HM724

HM725

HM726

HM727

HM728

HM729

HM730

RR Creek

Portal Effluent

Portal Effluent

Portal Effluent

RR Creek

RR Creek

RR Creek

RR Creek

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Copper Creek

Copper Creek

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

O.05

<0.05

<0.05

<0.05

<0.05

O.05

<0.5 .<(

<0.5 <(

<0.5 <(

<0.5 <(

0.5 '<(

<0.5 <(

0.6 <C

0.6 <C

0.6 <(

<0.5 <(

1.7 <(

1 <(

0.8 <(

<0.5 <(

1.7 <(

<0.5 <(

3.6 <(

<0.5 <(

<0.5 <(

<0.5 <(

<0.5 <(

<0.5 <(

<0.5 <(

<0.5 <(

<0.5 <(

<0.5 <(

<0.5 «

<0.5 «

<0.5 «

<0.5 «

).l 1.3

).l 4.6

).l 4.6

).l 4.5

).l 1.3

).l 3.4

).l 0.91

).l 1.2

).l 1.1

).l 2.5

).l 6.2

).l 1.6

).l 4.9

).l <0.05

).l 10

).l 1.8

).l 11

).l <0.05

).l 1.6

).l 4.2

).l 13

).l 1.7

).l 5.5

).l 16

).l >20

).l >20

3.1 1.7

3.1 >20

3.1 2.4

3.1 2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

<0.2

0.9

0.7

1.3

0.2

0.4

1.2

<0.2

0.7

0.2

0.3

1

0.4

<0.2

1.4

0.3

0.3

0.2

<0.2

0.7

<0.2

<0.2

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

0.1

5.3

5.3

5.1

<0.1

3.8

<0.1

0.1

<0.1

>20

4.7

2.8

1.7

11

14

0.9

7.4

1.3

0.9

5.5

1.8

0.2

4.6

4.9

4

2

0.2

9.7

<0.1

<0.1

<0.05

0.3

0.1

0.06

<0.05

0.05

<0.05

<0.05

<0.05

74

55

55

20

21

85

0.42

38

12

11

55

37

0.06

57

23

16

10

0.08

28

<0.05

<0.05

<0.5

1.3

1.4

1.3

<0.5

1

<0.5

<0.5

<0.5

18

16

>20

>20

>20

>20

1.2

11

9.2

12

18

13

<0.5

>20

15

15

13

<0.5

>20

<0.5

<0.5

<10 <0.05

<10 0.13

<10 0.12

<10 0.13

<10 <0.05

<10 0.09

<10 <0.05

<10 <0.05

<10 <0.05

<10 . 0.32

<10 0.28

20 0.37

<10 O.S7

<10 0.34

<10 0.49

<10 <0.05

<10 0.14

<10 0.16

<10 0.12

<10 0.11

<10 <0.05

<10 <0.05

<10 0.23

<10 0.12

<10 0.1

<10 0.12

<10 <0.05

<10 0.07

<10 <0.05

<10 <0.05

1.6

>20

18

11

1.4

9.7

<0.5

2

1

>20

>20

>20

>20

>20

>20

4.7

>20

>20

>20

>20

>20

1.5

>20

>20

>20

>20

1.9

>20

<0.5

<0.5

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

9.2

6.3

7.6

2.2

2.5

13

<0.05

6.3

2

1.8

7.2

3.5

<0.05

6

2.8

2

1.4

<0.05

4.4

<0.05

<0.05
Sample # Source

Table 3. ICP-MS analysis of filtered and acidified water samples collected at the Holden mine

Elemental concentrations expressed as ug/L

Hf Ho In La Li Mg Mo Mb Nd Ni Pb Pr Rb 

HM700

HM702

HM703

HM704

HM705

HM706

HM707

HM708

HM709

HM710

HM711

HM712

HM713

HM714

HM715

HM716

HM717

HM718

HM719

HM720

HM721

HM722

HM723

HM724

HM725

HM726

HM727

HM728

HM729

HM730

RR Creek

Portal Effluent

Portal Effluent

Portal Effluent

RR Creek

RR Creek

RR Creek

RR Creek

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Copper Creek

Copper Creek

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

0.09

0.08

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

1.8

1.2

1.4

0.42

0.49

0.24

<0.05

1.2

0.36

0.3

1.3

0.64

<0.05

1.2

0.53

0.38

0.27

<0.05

0.82

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

0.28

0.08

1.1

0.15

0.11

0.13

<0.05

0.05

<0.05

<0.05

0.06

<0.05

<0.05

0.13

0.1

0.06

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

0.18

0.1

0.05

<0.05

<0.05

<0.05

<0.05

<0.05

33

27

24

12

13

42

0.29

15

4.7

4.8

21

14

<0.05

26

7.7

5.6

4.2

0.05

12

<0.05

<0.05

0.3

>20

>20

>20

<0.3

19

0.4

0.7

<0.3

>20

>20

>20

>20

>20

>20

0.8

>20

>20

>20

>20

>20

0.6

>20

>20

18

>20

0.6

>20

<0.3

<0.3

730

>1000

>1000

>1000

390

>1000

380

540

420

>1000

>1000

>1000

>1000

>1000

>1000

>1000

>1000

>1000

>1000

>1000

>1000

890

>1000

>1000

>1000

>1000

>1000

>1000

510

510

0.5

1

1

1.1

0.6

0.9

0.6

0.6

0.6

0.1

0.1

<0.1

<0.1

<0.1

0.2

0.5

0.1

<0.1

<0.1

0.1

<0.1

0.6

<0.1

<0.1

<0.1

<0.1

0.5

<0.1

0.5

0.5

<0.1 <0.05

<0.1 0.17

<0.1 0.05

<0. 1 <0.05

<0.1 <0.05

<0. 1 <0.05

<0.1 <0.05

<0.1 <0.05

<0.1 <0.05

0.1 36

<0.1 22

<0;1 30

<0.1 9.3

<0.1 10

<0.1 43

<0.1 0.18

<0.1 22

<0.1 9

<0.1 6.7

<0.1 28

<0.1 17

<0.1 <0.05

<0.1 25

<0.1 11

<0.1 7.4

<0.1 5.6

<0.1 <0.05

<0.1 14

<0.1 <0.05

<0.1 <0.05

<1

<1

<1

<1

<1

<1

<1

<1

<1

>20

>20

19

>20

>20

>20

2

11

7

7

12

7

<1

18

10

9

9

<1

12

<1

<1

<0.05

0.17

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

0.33

0.46

2.6

<0.05.

0.13

3.2

<0.05

1.4

0.53

0.36

1.1

5.7

<0.05

2.7

2.5

2

1.4

<0.05

0.22

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

8.9

5.9

7.2

2.3

2.5

11

<0.05

5

1.9

1.6

6.5

4

<0.05

6.3

2.4

1.7

1.3

<0.05

3.4

<0.05

<0.05

0.6

6.2

6.2

6.1

0.5

4.6

0.5

0.6

0.5

30

33

38

30

30

37

1

16

13

11

21

15

0.6

28

14

13

14

0.6

14

0.5

0.5
Sample # Source Tb

Table 3. ICP-MS analysis of filtered and acidified water samples collected at the Holden mine

Elemental concentrations expressed as ug/L

Te Th Tl Tm U V w Yb Zn Zr

HM700

HM702

HM703

HM704

HM705

HM706

HM707

HM708

HM709

HM710

HM711

HM712

HM713

HM714

HM715

HM716

HM717

HM718

HM719

HM720

HM721

HM722

HM723

HM724

HM725

HM726

HM727

HM728

HM729

HM730

RR Creek

Portal Effluent

Portal Effluent

Portal Effluent

RR Creek

RR Creek

RR Creek

RR Creek

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Tailings Seep

Tailings Seep

Tailings Seep

RR Creek

Tailings Seep

Copper Creek

Copper Creek

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

1.6

1

1.3

0.37

0.43

2.1

<0.05

1.1

0.37

0.28

1.3

0.63

<0.05

1.1

0.5

0.36

0.25

<0.05

0.75

<0.05

<0.05

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.05 <C

<0.05 <C

<0.05 <C

<0.05 <C

<0.05 <C

<0.05 <C

<0.05 <C

<0.05 <C

<0.05 <C

1.2 <C

0.93 <C

3.2 <C

0.9 <C

0.88 <C

0.94 <C

<0.05 <C

0.42 <C

0.88 <C

0.4 <C

2.1 <C

2.3 <C

<0.05 <C

3.2 <C

1 <C

0.56 <C

0.64 <C

<0.05 <C

0.06 <C

<0.05 <C

<0.05 <C

1.1 <0.05

).l <0.05

1.1 <0.05

).l <0.05

1.1 <0.05

).l <0.05

1.1 <0.05

).l <0.05

1.1 <0.05

).l 0.52

1.1 0.35

1.1 0.49

1.1 0.15

1.1 0.16

1.1 0.82

1.1 <0.05

1.1 0.42

1.1 0.14

).l 0.12

).l 0.46

1.1 0.24

1.1 <0.05

1.1 0.38

1.1 0.21

1.1 0.14

1.1 0.1

1.1 <0.05

).l 0.27

).l <0.05

(.1 <0.05

0.02

0.28

0.28

0.2

0.02

0.06

0.02

0.03

0.02

3.3

1.6

7.4

1.2

1.4

8.3

0.03

7.5

1.7

1

5.7

2.1

<0.02

3.9

4.9

3.5

2.1

<0.02

4

<0.02

<0.02

<10 <0.05

<10 0.09

<10 0.12

<10 0.1

<10 <0.05

<10 0.09

<10 <0.05

<10 <0.05

<10 <0.05

10 <0.05

<10 <0.05

>20 <0.05

<10 <0.05

<10 <0.05

20 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<10 <0.05

<0.1

0.4

0.1

<0.1

<0.1

<0.1

<0.1

<0.1

<0.1

77

62

51

18

22

96

0.5

35

9.6

9.1

41

19

<0.1

46

16

11

7.5

<0.1

29

<0.1

<0.1

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

<0.05

2.7

1.8

2.9

0.85

1

4.6

<0.05

2.5

0.92

0.64

2.6

1.3

<0.05

2.1

1.2

0.86

0.61

<0.05

1.6

<0.05

<0.05

>20

>20

>20

>20

2.8

>20

0.8

>20

5.7

>20

>20

>20

>20

>20

>20

>20

>20

>20

>20

>20

>20

>20

>20

>20

>20

>20

>20

>20

<0.5

<0.5

<0.1

<OJ

<0.]

<OJ

<0.]

<OJ

<0.1

<OJ

<0.1

0.2

<0.1

0.5

0.2

0.1

1

<0.1

0.2

<0.1

<O.I

0.1

<0.1

<0.1

0.2

<0.1

0.5

<0.1

<0.1

<0.1

<0.1

<0.1
Table 4. Secondary sulfate minerals identified at the base of the Holden mill tailings, July 1994.

MINERAL FORMULA

Pickeringite MgAl2 (SO4)4 22H2O

Hexahydrite MgSO4 6H2O

Alunogen A12(SO4)3 17H2O

Halotrichite FeuAl2(SO4)4 22H2O

Siderotil Fe»SO4 5H2O

Melanterite Fe"SO4 7H2O

Rozenite Fe«SO4 4H2O

Romerite FenFem(SO4)4 14H2O

Jarosite KFe3«i(SO4)2(OH)6

Anterlerite f Cu3(SO4)(OH)4

Chalcanthite * CuSO4 5H2O

Bonattite CuSO4 3H2O

Dietrichite (Zn, Fen, Mn)Al2(SO4)4 22H2O

Gunningite (Zn, Mn)SO4 H2O

Gypsum CaSO4 2H2O

Table 5. Secondary sulfate minerals identified in the abandoned Holden mill, July 1995.

MINERAL FORMULA

Starkeyite MgSO4 4H2O

Alunogen A12(SO4)3 17H2O

Siderotil Fe"SO4 5H2O

Rozenite Fe«SO4 4H2O

Bilinite Fe«Fe"'(SO4)4 22H2O

Hyronium Jarosite (H3O)Fe3in(SO4)2(OH)6

Natrojarosite NaFe^SO^OHX

Ammoniojarosite (NH4)Fe3In(SO4)2(OH)6

Butlerite Fe'^SO^OH) 2H2O

Xitieshanite Fe"'(SO4)(OH) 7H2O

Antlerite Cu3(SO4)(OH)4

Chalcanthite CuSO4 5H2O

Bonattite CuSO4 3H2O

Gunningite (Zn, Mn)SO4 H2O

33
Table 6. Secondary sulfate minerals identified in the abandoned Holden mill, May 1996. 

MINERAL FORMULA

Pickeringite

Epsomite

Hexahydrite

Halotrichite

Siderotil

Melanterite

Rozenite

Romerite

Chalcanthite

Antlerite

Goslarite

Bianchite

Gypsum

MgAl2(SO4)4 -22H2O

MgSO4 7H2O

MgSO4 '6H2O

Fe»Al2 (SO4)4 -22H2O

Fe«SO4 '5H2O

Fe"SO4 '7H2O

Fe"SO4 -4H2O

FenFe"'(SO4V 14H2O

CuSCV 5H2O

Cu3(S04)(OH)4

ZnSO4 '7H2O

(Zn, Fe")SO4 6H2O

CaSO4 -2H2O

34
120°30

460OQ'

WENATCBDEE

NATIONAL

FOREST

Devils 

Smoke 

SUck

Figure 1. Location of (he Hoklcn Mine, Chclan County, Wastlington

35
Intermittent , 

Drainage-\j

i Portal Drainage

Diversion /V^/-^'728

v . Tailings Pile 1 714 N-Ephe^ml X?M

1 

N Honeymoon Heights Area

Figure 2. Holden mine site map showing the location of water samples collected in September 1996