SUBSURFACE WATERS AT MALAKOFF DIGGINS: PIT, NORTH

Transcription

BLOOMFIELD TUNNEL AND HILLER TUNNEL
____________
A Thesis
Presented
to the Faculty of
California State University, Chico
____________
In Partial Fulfillment
of the Requirements for the Degree
Master of Science
in
Environmental Science
____________
by
© David Holl Demaree 2013
Fall 2013
A Thesis
by
David Holl Demaree
Fall 2013
APPROVED BY THE DEAN OF GRADUATE STUDIES
AND VICE PROVOST FOR RESEARCH:
_________________________________
Eun K. Park, Ph.D.
APPROVED BY THE GRADUATE ADVISORY COMMITTEE:
______________________________
Guy Q. King, Ph.D.
Graduate Coordinator
_________________________________
Carrie Monohan, Ph.D., Chair
_________________________________
Susan Riggins, Ph.D.
_________________________________
Glen Pearson
PUBLICATION RIGHTS
No portion of this thesis may be reprinted or reproduced in any manner
unacceptable to the usual copyright restrictions without the written permission of the
author.
iii
ACKNOWLEDGMENTS
I would like to thank my thesis advisor Dr. Carrie Monohan for guiding me
through the process of doing studies outside of the Laboratory and through writing a
thesis. I would like to thank my whole committee including Dr. Susan Riggins and Glen
Pearson for the advice and for motivating me to get this thesis done.
Thanks to Dr. David Brown for guiding me through the CSU Chico
bureaucracy, teaching me how to do field studies and how to dig holes.
I would like to thank everyone who gave me advice Dr. Terrance T. Kato, Dr.
Karin Hoover, Dr. Katherine Gray.
Thank you CSU Chico, The Sierra Fund, The Sierra Nevada Conservancy,
and the CSU Chico Center for Water and the Environment for funding and material
support. The US Department of Parks and Recreation for allowing me to study Malakoff
Diggins and place borings.
The graduate students of the working group—Kathy Berry-Garrett, Cami
Ligett, Keith Landrum, Rebecca Bushway, Rajmir Rai, Harihar Nepal, Susan Miller
The undergraduate students who helped me out in the field—Travis Moore
and Morgan Blofsky
Funding for this project has been provided in part by the Sierra Nevada Conservancy
and the State of California.
iv
TABLE OF CONTENTS
PAGE
Publication Rights ......................................................................................................
iii
Acknowledgments ......................................................................................................
iv
List of Tables..............................................................................................................
vii
List of Figures.............................................................................................................
viii
List of Nomenclature..................................................................................................
xi
List of Symbols...........................................................................................................
xiii
Abstract.......................................................................................................................
xiv
CHAPTER
I.
II.
Introduction ..............................................................................................
1
History ..........................................................................................
Geology ........................................................................................
Hydrology.....................................................................................
Comparison of Malakoff Diggins to Other Abandoned Mines ....
Standards and Laws......................................................................
Literature Review .........................................................................
Purpose .........................................................................................
5
10
14
17
19
20
22
Methods ....................................................................................................
24
North Bloomfield Tunnel .............................................................
Hiller Tunnel ................................................................................
Borings .........................................................................................
Laboratory Testing .......................................................................
Data Analysis................................................................................
24
28
28
32
33
v
CHAPTER
III.
PAGE
Results ......................................................................................................
36
Precipitation..................................................................................
Hiller Tunnel ................................................................................
Borings .........................................................................................
Low Level Mercury......................................................................
Principle Component Analysis .....................................................
Analysis of Variance ....................................................................
Correlation Matrix ........................................................................
36
36
47
51
62
65
67
68
Discussion.................................................................................................
71
Hiller Tunnel ................................................................................
Borings .........................................................................................
Statistical Analysis .......................................................................
Blue Lead......................................................................................
Dissolved Oxygen ........................................................................
Limitations....................................................................................
Why Piper and Stiff Diagrams Were Not Used............................
71
81
83
90
91
92
93
94
V.
Conclusions ..............................................................................................
95
IV.
Recommendations ....................................................................................
98
References Cited.........................................................................................................
101
IV.
Appendix
A.
Tables .......................................................................................................
vi
108
LIST OF TABLES
TABLE
PAGE
1.
Location of Mouth and Shafts of the North Bloomfield Tunnel ..............
39
2.
Specific Yield of Borings .........................................................................
56
3.
ANOVA of Data at Malakoff Diggins .....................................................
68
4.
Correlation Matrix between Constituents.................................................
69
5.
Correlation Matrix between Sample Sites................................................
70
6.
Solid samples from Fleck et al. 2010 and Water Samples
from the Mouth on 2/13/2012 and Shaft 5 on 3/26/2012..................
73
Solid samples from Fleck et al. 2007 and water samples
from this study ..................................................................................
80
Hiller Tunnel from NCRCD Phase III Study (2/13/1979)
and this study ....................................................................................
81
7.
8.
vii
LIST OF FIGURES
FIGURE
PAGE
1.
Map of Malakoff Diggins, California.......................................................
2
2.
Surface Water in the Pit at Malakoff Diggins ..........................................
15
3.
Hiller Tunnel Adit ....................................................................................
18
4.
North Bloomfield Tunnel .........................................................................
25
5.
Locations of Borings ................................................................................
29
6.
Boring Design...........................................................................................
30
7.
Explanation of Biplot ...............................................................................
34
8.
Precipitation for the 10/1/2012 - 4/15/2012 Monitoring Period...............
37
9.
Locations of Mouth and Shafts of North Bloomfield Tunnel
from Google Earth Overlaid by (PBTGM, 1872) .............................
38
10.
Conceptual Model for the Hydrology of North Bloomfield Tunnel ........
43
11.
Average Electrical Conductivity (EC), pH and Temperature
of standing water in the Mouth and Shafts of the
North Bloomfield Tunnel..................................................................
45
12.
As, Cr, Cu, and Pb in North Bloomfield Tunnel ......................................
46
13.
Ba, Zn and Ni in North Bloomfield Tunnel .............................................
47
14.
Constituents of Mouth and Shafts in mg/L...............................................
48
15.
Temperature Change in Hiller Tunnel......................................................
49
16.
pH Change of Hiller Tunnel .....................................................................
49
viii
FIGURE
PAGE
17.
Conductivity change of Hiller Tunnel......................................................
50
18.
Trace Metals in Hiller Tunnel and Diggins Pond.....................................
51
19.
Fe, Al, and Mn in Hiller Tunnel and Diggins Pond .................................
52
20.
Fe, Ca, Mg and SO4 in Hiller Tunnel and Diggins Pond .........................
53
21.
Boring Wet Up Period ..............................................................................
54
22.
Boring P-2 Water Height from Bottom of Boring,
Surface Water, and Precipitation ......................................................
55
23.
Temperature Changes in Borings .............................................................
57
24.
Changes Over Time pH ............................................................................
57
25.
Conductivity Changes in Borings Over Time ..........................................
58
26.
Trace metals in Borings, Hiller Tunnel and Diggins Pond ......................
60
27.
SO4, Fe, Ca, Mg, SO4 in Hiller Tunnel, Borings......................................
61
28.
SO4, Al, Mn, K, Na in Hiller Tunnel, Borings .........................................
62
29.
Metal Concentrations in Borings from 11/4/2012 to 3/22/2013 ..............
63
30.
Total Hg in at Malakoff Diggins ..............................................................
64
31.
Dissolved Mercury at Malakoff Diggins..................................................
65
32.
Biplot of the Waters of Malakoff Diggins based on Metals
Concentration ....................................................................................
66
Biplot of Waters at Malakoff Diggins Based on Metals, Sulfate
and Alkalinity....................................................................................
67
34.
Mouth of North Bloomfield Tunnel Undisturbed ....................................
78
35.
Metals at Gage 3 and North Bloomfield Tunnel ......................................
79
33.
ix
FIGURE
36.
PAGE
Metals and Sulfate in Surface Water in the Pit of
Malakoff Diggins ..............................................................................
87
37.
Bailer Drawn from Boring P-1 on 10/12/2012.........................................
89
38.
Oxidation-reduction Conditions in Soils in the Pit ..................................
93
x
LIST OF NOMENCLATURE
Auriferous gravel – Alluvial sediment that was deposited at Malakoff Diggins forming a
placer deposit. The gravel was named for “auri” – gold and “ferrous” – iron, the
deposit contained iron and gold.
Central Valley – California Central Valley
Coast Range – California Coast Range
Develop (boring) – After a boring is placed in the ground it is developed by drawing
water from it until it the water is clear. This represents the point at which material
around the boring has settled and stabilized.
DWR – California Department of Water Resources
EPA – United States Environmental Protection Agency
EPA ### - Standard testing methods set by the EPA
Gold Rush – California Gold Rush of 1849
Pit – The area of Malakoff Diggins that was excavated during the Gold Rush. Today the
Pit is 1.5 miles long, 0.5 miles wide and 170 ft deep.
Sediment – The material that has deposited in the Pit after the pit was excavated.
Sierra Nevada – Sierra Nevada Mountains, California, USA
SM – Standard Method approved by the EPA from Clesceri et al., 1999
xi
Title 22 Metals – Metals regulated under Title 22 of the California Code of Regulations.
Title 22 Metals are Al, As, Ag, Ba, Be, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni,
Pb, Sb, Se, Tl, Zn
xii
LIST OF SYMBOLS
°C – degrees Celsius
µg/L – microgram per liter
cfs – ft3/s - cubic feet per second
cm – centimeters
ft– feet
km - kilometers
L – liters
m – meters
mg/L – milligram per liter
ms/cm2 – millisiemens per centimeter squared
ng/L – nanogram per liter
pH – pH = -log[H+], [H+] – concentration of H+ in moles/liter or molarity
Elements and polyatomic ions are listed by their name or symbol on the periodic table –
example, Silver - Ag or Sulfate – SO42-
xiii
ABSTRACT
by
© David Holl Demaree 2013
Master of Science in Environmental Science
California State University, Chico
Fall 2013
Malakoff Diggins, a historic hydraulic mine, has the potential to degrade
habitat in the Humbug Creek and South Yuba River watershed with discharges of
sediment, copper, mercury, nickel and zinc.
Subsurface waters in three areas of Malakoff Diggins, (1) North Bloomfield
Tunnel, including eight airshafts, six contained standing water, (2) Hiller Tunnel, and (3)
borings in the Pit near Hiller Tunnel, were studied to identify potential sources of metals.
Water chemistry (pH, electrical conductivity, total metals and common ions)
similarities and physical characteristics (water level) between mine features were used to
determine the connections between mine features and subsurface water flow.
The metal concentrations were variable in areas studied at Malakoff Diggins.
All portals and shafts of the North Bloomfield Tunnel were at least partially blocked,
however the downstream portal of the tunnel and Shaft 5, had continuous surface water
xiv
discharge to Humbug Creek. The degree to which the standing water between the shafts
are connected, through fractured rock or otherwise, was difficult to determine, however
some shafts, specifically Shaft 5 (had the highest metal concentrations) and 6, had similar
water chemistries. Two borings of four shallow groundwater borings in the Pit, P-1 and
P-2, had similar water chemistry. The borings in the Pit had higher concentrations of
metals than the surface waters in the Pit and Hiller Tunnel. The concentrations of metals
in the waters at Malakoff Diggins are likely related to concentrations of suspended
sediment and represent an ongoing source of heavy metals to surface waters.
xv
CHAPTER I
INTRODUCTION
Gold mining during the California 1849 Gold Rush heavily impacted the
environment of California. The California Department of Conservation - Mine
Reclamation estimates that there are 47,084 abandoned mines in California and many of
the abandoned mines are in the Sierra Nevada Mountain Range (Newton et al., 2000).
One of the largest historic mine sites in the Sierra Nevada Mountain Range is Malakoff
Diggins which is currently a California State Historic Park. Malakoff Diggins continues
to impact downstream waterways because it continues to discharge water with high loads
of sediment, mercury, copper and zinc (California Regional Water Quality Control
Board-Central Valley Region [CRWQCB-CVR], 2004). The purpose of this study was to
characterize the subsurface water quality at Malakoff Diggins associated with specific
mine features to inform remediation efforts.
Malakoff Diggins is in the western foothills of the Sierra Nevada Mountain
Range in Nevada County, CA, 28 miles (45 km) north of Nevada City, and 65 miles (105
km) northwest of Sacramento at an elevation of approximately 3000 ft (915 m) (Figure
1).
Most of the precipitation at Malakoff Diggins occurs during the rainy season,
from November to April, with an average precipitation of 55-60 inches (140-150 cm)
(Nevada County Resource Conservation District [NCRCD] 1979a). The temperatures at
1
2
Figure 1. Map of Malakoff Diggins, California.
Note: Satellite image of Malakoff Diggins with a map of California and the
location of Malakoff Diggins in the bottom right corner. Brown Line – Border
of Malakoff Diggins State Historic Park, White Line – Tunnels, White Dots –
Tunnel openings, Blue Dashed Lines – Water. Inset Map Bottom Left Corner
– Map of California. Star – Sacramento, Square Malakoff Diggins, Red LinesFreeways, Blue – Major Rivers
3
Malakoff Diggins range from an average high of 92°F (33°C) to an average low of 30°F
(-1°C) (NCRCD 1979a). The first freeze typically occurs early November and the last
freeze typically occurs mid-April (NCRCD, 1979a). Many of the streams which flow into
Malakoff Diggins are seasonal, though there are some springs that flow into Malakoff
Diggins all year round. However, during the wet season Malakoff Diggins pit acts as a
large catchment area and discharges turbid water through Hiller Tunnel into Diggins
Creek, Humbug Creek, and the South Yuba River
The most visible part of Malakoff Diggins from the air is the Pit (Figure
1).The Pit is approximately 1.5 miles (2.5 km) long from east to west, 0.5 miles (0.8 km)
across from north to south and 170 ft (52 m) deep at the time of this study (Figure 1). The
Pit was formed by hydraulic monitors washing away the auriferous gravels. Due to the
historic mining, the Pit has badlands topography. The eastern end of the Pit is known as
the slump area (NCRCD, 1979a). The slump area is where the most erosion and
deposition has occurred in the Pit. The elevation of the bottom of the Pit decreases
westward from the slump area until it reaches its lowest point at Diggins Pond and the
inlet to Hiller Tunnel. The cliffs on the northern side of the Pit are the highest and
become smaller southward. The southeastern side of the Pit is covered with tailings piles,
which may be relics from a unique period of the mines history when hydraulic mining
was banned and miners were not allowed to discharge their tailings downstream. The
miners at Malakoff found ways to hold processed material, or tailings on site in the pit.
The headwaters of Humbug Creek are north of the historic town of North
Bloomfield, which was established to the east of the Pit for miners (Figure 1). Humbug
Creek runs along the west side of the town of North Bloomfield then curves around the
4
south side of the town. Humbug Creek continues along the outside of the southern rim of
the Pit before turning south where it is joined by Diggins Creek. Humbug Creek then runs
south approximately 1.86 miles (3 km) until it joins the South Yuba River.
Hiller Tunnel runs north-south through the southern edge of the Pit (Figure 1).
Hiller Tunnel is approximately 465 ft long, 7 ft high, and 5 ft wide at the time of this
study. Hiller Tunnel is traversable during the dry season and it is possible to walk all the
way through the tunnel. Stalactites are beginning to grow on the ceiling of the tunnel.
Water runs along the floor of the tunnel. The floor is covered with fine orange sediment
with rubble strewn through it ranging in size from one inch to one foot in diameter. Hiller
Tunnel is the main surface water drainage for the Pit. Diggins Creek starts at the outlet of
Hiller Tunnel and runs 0.3 miles (0.5 km) until it joins Humbug Creek.
North Bloomfield road starts north of Nevada City, winds north, crosses the
South Yuba River at Edwards Crossing and continues to Malakoff Diggins. At Malakoff
Diggins it runs between the Pit and Humbug Creek, through the town of North
Bloomfield where it turns north.
The Humbug Trailhead is on the North Bloomfield road before it crosses
Diggins Creek. The Humbug Trail winds along the slopes on the west side of Humbug
Creek till it joins South Yuba Trail at the Humbug Creek – South Yuba River confluence.
Approximately 200 ft down the Humbug Creek Trail from the North Bloomfield Road
the trail goes over an unnamed drainage that comes from the area southwest of the pit that
was also hydraulically mined. Approximately a half mile down Humbug Trail from the
North Bloomfield Road is the Exploration Campground which is in a clearing next to
5
Humbug Creek east of the Humbug Trail. Approximately 1 mile down the Humbug
Creek Trail from the road is a series of waterfalls on Humbug Creek.
The North Bloomfield Tunnel starts in the Pit north of the upstream portal to
Hiller Tunnel in the Pit. From the Pit the North Bloomfield Tunnel runs south along
Humbug Creek ending south and downstream of the waterfall on Humbug Creek.
The vegetation in the Pit is highly variable and depends on hydrologic and
geologic conditions. Rushes and grasses grow in the marshy areas around Diggins Pond
in the south west side of the Pit and near the springs in the slump area in the east side of
the pit (Nevada County Resource Conservation District, 1978). Arroyo willow (Salix
lasiolepis) and white alder (Alnus rhombifolia) grow in the seasonal marshy areas created
during the rainy season on the west side of the Pit (NCRCD, 1979a). Eastward the
willows transitions to wild oats (Avena fatua) and brome (Bromus) grasses in the center
of the Pit (NCRCD, 1979a). Eastward the grasses thin out at the slump area. Ponderosa
pine (Pinus ponderosa) grow in the slump area. Manzanita (Arctostaphylos) and
Ceanothus are in the drier areas on the edge of the Pit and on the tailings piles (NCRCD,
1979a). The area surrounding the Pit was covered with ponderosa pine forest, which also
includes incense cedar (Calocedrus), Douglas fir (Pseudotsuga menziesii), white fir
(Abies concolor), sugar pine (Pinus labertiana) and black oak (Quercus kelloggii)
(NCRCD, 1979a).
History
Mining began at Malakoff Diggins in 1851 during the California Gold Rush
(Jackson, 1967). The first miners at Malakoff used shovels, pans and sluices to mine
6
placer gold in Humbug Creek. In 1867, the North Bloomfield Gravel Mining Company
(NBGMC) was formed and hydraulic mining began at Malakoff Diggins in order to
access placer gold in auriferrous gravels in the hillside deposited by an ancient river
(Jackson, 1967). The peak period of mining was after the completion of the North
Bloomfield Tunnel in 1875 until the Sawyer Decision, which put a ban on hydraulic
mining in 1884.
The Pit was created by hydraulic mining at Malakoff Diggins. Hydraulic
mining is performed by using a monitor, a high-pressure hose, to erode a hillside by
spraying water on it. Hydraulic mining was used to mine the auriferous gravel at
Malakoff Diggins because the auriferous gravel is composed of loose alluvial material
that is easily mobilized when washed with the monitors. Explosives were used to break
up more consolidated auriferous gravel before using monitors (Whitney, 1880; NBGMC,
1898b). A slurry was formed by the mixture of gravel and water. The process uses a lot
of water and the auriferous gravel at Malakoff Diggins was in a bedrock channel that
retained water, so Hiller Tunnel and North Bloomfield Tunnel were built to drain the
slurry out of the Pit.
To extract gold from the slurry a series of flumes, sluices and undercurrents
extended a quarter mile down Humbug Creek from the mouth of North Bloomfield
Tunnel (Jackson, 1967). The sluices and undercurrents allowed the dense gold to settle
out of the slurry while the rest of the slurry remains mobilized. Mercury was added to the
flumes, sluices and undercurrents because it is dense and will form an amalgam with gold
and is not very soluble in water and will not form an amalgam with most of the other
materials in the slurry. Copper plates were often placed on the bottom of flumes, sluices
7
and undercurrents to collect excess mercury that did not amalgamate with gold. The goldmercury amalgam was cleaned out of the sluices and heated to evaporate the mercury, in
a process called retorting, leaving behind the mercury free gold.
According to Mr. Bowie, the mining engineer at Malakoff Diggins, mercury
was not just placed in the flumes and sluices but also on the hillsides before an area was
washed with monitors and in the tunnels (Jackson, 1967). The North Bloomfield Tunnel
was used as a sluice by placing wooden blocks in the tunnel to act as riffles that slows the
slurry allowing heavy particulates such as gold and gold-mercury amalgam to settle out
behind the riffles (NBGMC, 1898a). The tunnels were cleaned out for gold when there
was not enough water to hydraulically mine usually during the late summer or early fall,
and between runs (NBGMC, 1898a).
During the Gold Rush from 1850-1981, 26,000,000 lbs (12,000,000 kg) of
mercury was used in mines in the Sierra Nevada including Malakoff Diggns, and 38,000,000 lbs (1,400,000-3,600,000 kg) was not recovered and is still in the environment
(Alpers and Hunerlach, 2000). Most of the mercury used during the Gold Rush was
mined in the Coast Range, which is on the west coast of California (Alpers and
Hunerlach, 2000). Much of the mercury used in the Sierra Nevada during the Gold Rush
is still in the environment today. In the environment, mercury has multiple forms.
Mercury can be bound to particulates and sediment, suspended, and dissolved in water, as
a gas or it can form methyl mercury, a neurotoxin.
Hiller Tunnel was only deep enough to allow the top layer of the auriferous
gravel to be mined. North Bloomfield Tunnel was built deeper than the Hiller Tunnel
because to mine the deeper and richer auriferous gravel (Smith, 1871). As part of the
8
construction of the North Bloomfield Tunnel eight air shafts were constructed. The shafts
are numbered from one to eight. The shafts were numbered from 1 to 8. Shaft 8 is in the
Pit and the number decreases toward the mouth of the North Bloomfield Tunnel. The
eight shafts allowed 16 teams to dig the tunnel simultaneously to quickly complete the
tunnel (Smith, 1871). The shafts are vertical holes that connect the North Bloomfield
tunnel to the surface and were used for construction of the tunnel and to remove material
from the tunnel. While Malakoff Diggins was in operation the purpose of the shafts was
not to bring fresh air to people in the tunnel, since the tunnel was filled with water and
slurry making it hazardous for anyone to enter (Jackson, 1967).
Construction began on the North Bloomfield Tunnel in April or May of 1872
and was finished on November 15, 1874 (Jackson, 1967). Jackson included a detailed
account of tunnel construction given by Raymond, a reporter for the government while
hydraulic mining was occurring at Malakoff Diggins (Jackson, 1967). According to
Raymond, the North Bloomfield Tunnel was 7920 ft (2400 m) long and each of the eight
shafts were approximately 1000 ft (304 m) apart (Jackson 1967). All the shafts were 4.5
ft (1.4 m) by 9 ft (2.7 m) wide and had an average depth of 197 ft (60 m) (Jackson, 1967).
The tunnel was 6.5 ft (2 m) high and 6 ft (1.8 m) wide from the mouth to Shaft 6 and 8 by
8 ft (2.4 m) from Shaft 6 to Shaft 8 (Jackson, 1967). Shaft 8 (upstream portal) was dug 75
ft into the bedrock below the gravel and the mouth of the tunnel (downstream portal) was
440 ft (135 m) below the gravel/bedrock in the Pit (Jackson 1967). The elevation of the
bedrock at Shaft 8 was estimated to be at 2,929 ft (893 m) (Whitney, 1880). The accounts
of the North Bloomfield Tunnels are consistent with the Plan of North Bloomfield Tunnel
and Gravel Mines (North Bloomfield Gravel Mining Company [NBGMC], 1872).
9
In the years after the North Bloomfield Tunnel was completed several million
tons of gravel were run through the tunnel (NBGMC, 1877). The gravel running through
the North Bloomfield Tunnel eroded the floor 16 inches (41 cm) and smoothed the walls
(NBGMC, 1877). Preparations were made to expand the North Bloomfield Tunnel by
adding a secondary tunnel from Shaft 7 to exploratory Shaft 1 (NBGMC, 1877). The
secondary tunnel from Shaft 7 was mapped by Hoffman (1872) and Uren (1932), but it
was not found in written records after 1877.
Once the North Bloomfield Tunnel was completed, the Pit quickly expanded
exposing bedrock in places. At the beginning of the 1876 mining season the Diggins floor
was 40 ft (12 m) above bedrock and by the end of the season 230 ft (70 m) radius of
bedrock was exposed around the entrance to North Bloomfield Tunnel (NBGMC, 1876).
According to Lindgren the bedrock was exposed at the bottom of the Diggins in an area
300-400 ft (90-120 m) wide and was relatively level (Lindgren and Walcott, 1900). Later
accounts give the dimensions of the Diggins as 5000 ft (1.5 km) long, 500-600 ft (150180 m) wide and 500 ft (150 m) deep (Lindgren and Walcott, 1900).
Farmers in the Central Valley sued the North Bloomfield Gravel Mining
Company because the slurry from hydraulic mines was flooding fields and cities
(Sawyer, 1884). This led to the Sawyer Decision of 1884, one of the first environmental
decisions in the USA, which placed a moratorium on hydraulic mining. After the Sawyer
Decision of 1884, impoundments and elevators were used to hold and move slurry, so
that sediment would not move downstream (Jackson, 1967). The Caminetti Act 1893
allowed hydraulic mining to continue with restraints such as impoundments for sediment.
10
Though there was a moratorium on hydraulic mining due to the Sawyer
decision in 1884, the 1898 water records from Malakoff Diggins document the clean out
of the North Bloomfield Tunnel and the amount of gold collected during the summer of
1898 (NBGMC, 1898a). It is unclear when mining officially ended at Malakoff Diggins.
Some of the dates that are mentioned for the end of operations at Malakoff Diggins are
1883 (Lindgren and Walcott, 1900) and Jackson notes the end of mining by 1900 (1967).
During the 1930s, there was a large landslide on the west rim of the Pit. The
landslide filled Shaft 8. Shaft 1 also collapsed during the 1930s (Jackson, 1967).
Afterward the Pit filled with water to a depth of 70 ft (21 m) (Jackson, 1967). Since then
the Pit has slowly filled with sediment and the water level decreased forming Diggins
Pond.
Geology
The Sierra Nevada Mountain Range was originally part of the sea floor. Uplift
and granitic pluton emplacement began as the North American and Pacific Plate collided
200 million years ago (Wakabayashi and Sawyer, 2001). The formation of plutons was
episodic and ended approximately 85 million years ago (Wakabayashi and Sawyer,
2001). The plutons metamorphosed the surrounding rocks forming gold bearing quartz
veins (Clark, 1970).
During the Eocene, a series of rivers eroded the ancestral Sierra Nevada
(Wakabayashi and Sawyer, 2001). The Eocene rivers deposited the eroded alluvial
material in bedrock channels (Lindgren and Walcott, 1900). The riverbed acts as a natural
sluice concentrating the gold in the alluvial material forming placer deposits. The placer
11
deposits at Malakoff Diggins are referred to as auriferous gravel (Saucedo et al., 1992).
The gold in placer deposits are often in the form of gold dust, as opposed to gold veins, or
nuggets.
The channels formed by the Eocene river deposits run from northwest to
southeast. The Sierra Nevada was volcanically active 35 - 5 million years ago
(Wakabayashi and Sawyer, 2001). The volcanism covered the Eocene river deposits with
ash and lava. The ash and lava was more resistant to erosion than the alluvial sediment
preserving the placer deposit. During the late Cenozoic there was a second series of uplift
events which created the Sierra Nevada as it exist today (Wakabayashi and Sawyer,
2001).
The geology of Malakoff Diggins consists of three rock units: (1) The top unit
is andesitic tuff which is part of the Mehrten Formation (Peterson, 1976), (2) In the
middle is auriferous gravel which is in a channel in bedrock basement, and (3)
Metamorphic bedrock basement.
The Mehrten Formation that caped the auriferous gravel at Malakoff Diggins
was estimated to be 2-20 ft (1-6 m) thick (Whitney, 1880) and is from the MiocenePliocene (Peterson, 1976). The Mehrten formation at Malakoff Diggins is composed of
breccia, basalt, andesite, andesite tuff, dacite tuff, horblende and albite (Bouslog, 1977;
Peterson, 1976; Saucedo et al. 1992). This includes intrusive andesite and ancient
mudflows consisting of breccia tuff and conglomerate (Saucedo et al., 1992).
The auriferous gravel was formed by deposition from the ancestral Yuba
River during the Eocene (Lindgren, 1911; Saucedo et al., 1992; Wakabayashi and
12
Sawyer, 2001). The auriferous gravel contains boulders, pebbles and cobbles and quartz
gravels and sands (Saucedo et al., 1992).
The auriferous gravel forms two layers the top is called "white gravel" and the
bottom is called "blue gravel" or "blue lead" (Smith 1871). The upper “white gravel”
layer composted of gravel, sand and clay which was 50-500 ft (15-150 m) thick. The
lower “blue gravel” which was composed of coarse gravel and large boulders that had a
“blue or greenish” color, the blue lead varied in thickness from a few feet to 140 ft
(1-43 m) (Smith, 1871; Whitney, 1880).
The white gravel is further divided into two layers approximately the top 100
ft was composed of light colored mature graves, sands and clays (Bouslog, 1977). The
gravels decreased in size going from the top to the base of the cliff, with more mature
sediment near the top of the edge of the Diggins (Yuan, 1979). The upper portion of the
Pit contained 53% granules and sand while the lower portion contained only 28% (Yuan,
1979). The lower portion contained more pebbles and cobbles while the upper portion
contained smaller portions of cobbles and pebbles (Yuan, 1979).
The “blue or greenish” color of the "blue gravel" is due to reduced species of
iron (Smith, 1871; Clark, 1970). The blue gravel was cemented and the miners used
explosives to loosen the blue gravel before it could be hydraulically mined (Jackson,
1967). The blue gravel had the most value because it contained the highest concentration
of gold (Smith, 1871).
The white and blue gravels were removed from a 5000-foot (1.5 km) long,
500-600-foot (150-180 m) wide area that makes up the Pit in 1900 (Lindgren and
Walcott, 1900). Since 1900, sediment has been filling the Pit. The majority of the
13
sediment in the Pit came from the slump area (NCRCD, 1979b). The cliffs in the slump
area were slumping due to clay in the soils (NCRCD, 1979a), that can range from 5-3 %
by weight sediment composing the cliffs (Yuan, 1979). The clay was mainly composed
of kaolinite (Yuan, 1979).
The bedrock at Malakoff Diggins has varying classification, which is partially
due to the bedrock in the Pit being covered by sediment during the 1930s (Jackson,
1976). Generally, the bedrock was formed during the Paleozoic/Mesozoic (Saucedo et al.,
1992). Lindgren and Walcott (1900) originally mapped the bedrock as the Delhi
Formation. Later investigators determined that the bedrock unit was not distinctive
enough to be classified (Clark, 1970; Peterson, 1976; Saucedo et al., 1992). The
descriptions of the bedrock at Malakoff Diggins are similar to those of the Calaveras
Complex. Byers et al. (1976) considered the Delhi Formation as part of the Calaveras
Complex.
Peterson studied outcrops along Humbug Creek and described the bedrock as
Paleozoic metamorphic rock consisting of phyllite, metachert, metavolcanic intermediate,
and slate (Peterson, 1976). The phyllite and metachert unit consists of black phyllite and
tan metachert (Peterson, 1976). The metachert was bedded and there are bands of marble
in the phyllite (Peterson, 1976). The slate was composed of clay slate and was
interbedded with hornblende-albite (Peterson, 1976).
Both the North Bloomfield Tunnel and Hiller Tunnel run through bedrock.
The bedrock is not uniform as noted from the drilling logs of the North Bloomfield
Tunnel (Jackson, 1967). The drill logs for the North Bloomfield Tunnel were vague and
are summarized briefly below. The drill log from the North Bloomfield Tunnel record the
14
construction from the mouth to Shaft 8 and this order is kept for this summary. From the
mouth of the North Bloomfield Tunnel the material was easy to dig through until harder
material was reached 300 ft (90 m) into the tunnel (Jackson, 1967). The first 72 ft (22m)
of Shaft 1 was loose material and the top 97 ft (30 m) had to be reinforced (Jackson,
1967). Shaft 2 had 65 ft (20 m) of black quartz (Jackson, 1967). Shaft 3 was rock the
entire length (Jackson, 1967). Shaft 4 followed a seam of rock for the first 100 ft Shaft 4
and water was pumped out of the shaft during construction (Jackson, 1967). Shaft 5 ran
through hard rock and water was pumped out of the shaft during construction (Jackson,
1967). Shaft 6 was rock the whole length but the rock below 140 ft (43 m) was harder
(Jackson, 1967). A section of the tunnel near Shaft 6 had to be timbered (Jackson, 1967).
Shaft 7 was composed entirely of hard rock (Jackson, 1967). Shaft 8 went through 110 ft
(33.5 m) of gravel at the top then 75 ft (23 m) of bedrock at the bottom (Jackson, 1967).
In the Pit, the bedrock in the Pit had a belt of granite 40-50 ft wide, which zigzagged
across it (Whitney, 1880) that may be dikes.
Hydrology
Surface water flows into the Pit from the surrounding areas. The general slope
of the topography of Malakoff Diggins is highest north of Malakoff Diggins at San Juan
Ridge. Elevation decreases south toward the South Yuba River. Most of the water that
flows into the Pit comes from streams that begin north of the Pit. The area north of the Pit
is composed of soil on top of volcanic material. The volcanic material, andesitic tuff,
could act as an impermeable barrier which would keep water near the surface, so less
water would saturate the soil increasing the runoff into the Pit during storm events.
15
The water coming into the Pit during storm events has eroded the sides of the
Pit creating many small channels and alluvial fans in the Pit (Nepal, 2013). The water in
the Pit tends to form braded channels on the floor of the Pit (Nepal, 2013). Water in the
southern part of the Pit flows along the southern edge of the Pit until it reaches Hiller
Tunnel (Figure 2). Water in the northern part of the Pit flows to Diggins Pond and from
Diggins Pond it flows into Hiller Tunnel (Nepal, 2013). Water fills
Figure 2. Surface water in the pit at Malakoff Diggins.
Note: Hiller Tunnel and dark blue line added to show water flow in the Pit.
Diggins Creek course altered from USGS, 2012 because Hiller Tunnel was not
taken into account. The Diggins Creek – Humbug Creek confluence is not shown
on this map and would be located south of Figure 2.
Source: Detail from US Geological Survey, 2012, North Bloomfield
quadrangle, California-Nevada County, 7.5-Minute Series: US Geological
Survey, scale 1:24 000, 1 sheet.
Diggins Pond and creates a marshy area in the west side of the Pit. The only drainage for
surface water in the Pit is Hiller Tunnel (Nepal, 2013).
16
During the dry season water flows from the springs in the slump area in the
east part of the Pit through the southern part of the Pit. The waters from the springs are
transparent but red and green algae grow in the springs.
Diggins Pond contains water during the dry season. Diggins Creek flows all
year round.
There are many factors that could affect ground water flow and infiltration in
the Pit and our knowledge of water flow in the Pit is limited. Water infiltration in the Pit
could be slow due to the amount of fine grain sand and clay in the sediment (Ward,
1995). Crusts could form on the ground surface slowing infiltration. Cracks in the crust's
surface could allow water into the soil increasing infiltration. Vegetation can create
macropores and preferred flow in areas where organic material has decomposed
increasing infiltration (Ward, 1995). Sediment is actively being deposited in the Pit, and
is not compacted by park use which could maintain relatively higher infiltration rates.
Beneath the sediment is bedrock which is expected to be impermeable. But
construction records of Shaft 4 and 5 show that there are zones of high permeability,
probably associated with bedrock fractures. The bedrock makes a channel in the Pit
which would restrict the flow of ground water. Potential drainages from the Pit are Hiller
Tunnel, Shaft 8 of the North Bloomfield Tunnel and the auriferous gravel channel that
runs through Malakoff Diggins. Ground water drainage from the Pit being slow is
supported by the fact that Diggins Pond has standing water in it all year.
Due to the geology of the bedrock that the North Bloomfield Tunnel and
Hiller Tunnel, water is expected to flow out of the pit in two ways, (1) through the
fractured rock, and (2) through the Hiller and North Bloomfield Tunnel excavations.
17
Fractured rock has variable flow regimes since water is flowing through
fractures in otherwise impermeable rock (Bear et al., 1993). The fractures make a limited
network through which water flows. In the North Bloomfield Tunnel surface water
discharges only from the surface at Shaft 5 and from the mouth of the tunnel but fractures
could act as conduits which would allow pollution from the North Bloomfield Tunnel to
spread to Humbug Creek and it would make it difficult to predict the effect of any
impoundments created as a part of any remediation effort at Malakoff Diggins (Hamlin
and Alpers, 1996).
Comparison of Malakoff Diggins to
Other Abandoned Mines
A common feature of abandoned mine sites including Malakoff Diggins is
orange colored particulate matter (Figure 3). The orange solids have many names; some
examples are, yellow boy, ocherous precipitate (Brady et al., 1986), iron oxide
precipitates (Stanton et al., 2007a, b), and hydrous ferrous oxide. Hydrous ferrous oxide
is the term chosen for this study. Hydrous ferrous oxide is formed by minerals
precipitating out of solution as solutions change from reducing to oxidizing conditions.
The minerals precipitating out of solution are mainly oxidized iron species such as
goethite and schwertmannite (Stanton et al., 2007a). The oxidation of iron is catalyzed by
bacteria (Stanton et al., 2007a).
Acid mine drainage is a common problem at abandoned coal and metal mines.
Acid mine drainage can occur at placer mines like Malakoff Diggins if there are sulfide
minerals present (Alpers et al., 2002). Acid mine drainage can occurs as sulfide minerals,
18
Figure 3. Hiller tunnel adit.
Note: Hiller Tunnel at Malakoff Diggins discharging hydrous
ferrous oxides. Photograph by Rebecca Bushway. Reproduced with
permission.
often in the form of pyrite, are oxidized and dissolved forming acid. The acidic waters
can dissolve other metal bearing minerals.
Acid mine drainage is not expected at Malakoff Diggins because the sediment
in the Pit is mainly composed of kaolinite clay, quartz sand and cobbles, instead of pyrite
or other metal rich minerals that lead to acid mine drainage. If there is acid mine drainage
at Malakoff Diggins it might be neutralized by the dissolution of other minerals in native
rock formations. The blue gravel may contain reduced iron species and has the potential
for acid mine drainage but it was removed from most of the Pit (Lindgren and Walcott,
1900). The rate of acid mine drainage and the concentration of mineral rich waters can
change seasonally (Church et al., 2007).
19
Standards and Laws
Due to the Sawyer Decision 1884 and Caminetti Act 1893 actions were taken
to mitigate some of damage that hydraulic mining had caused to the environment; for
example, the use of impoundments to hold back sediment in the rivers from the hydraulic
mines. By 1900, most hydraulic mines were abandoned because mitigation measures
were expensive and it was no longer economically feasible to mine gold. During the
Great Depression there was renewed interest in gold mining but interest decreased after
1933 Executive Order 6102 and in 1934 the Gold Reserve Act were passed that outlawed
most public possession of gold. Once the hydraulic mines were abandoned, little was
done to mitigate any further damage. To this day Malakoff Diggins continues to erode
sediment into the South Yuba River.
Another law that affects Malakoff Diggins was the Clean Water Act of 1972.
The goal of the Clean Water Act was to limit the amount of toxins and contaminants from
waters, and to restore and protect the beneficial uses of surface waters. The Clean Water
Act allowed the federal government and states to set loads for pollutants in surface water
depending on the beneficial uses of the water body and required permits to discharge into
surface waters.
The Surface Mining Control and Reclamation Act of 1977 made new mine
owners responsible for submitting a reclamation plan and bond when opening new mines.
The owners of Malakoff Diggins did not fall under the Surface Mining Control and
Reclamation Act because Malakoff Diggins was not operated after 1977.
20
Literature Review
Much of the information on the design and mine workings at Malakoff
Diggins, comes from Hamilton Smith Jr., who started working at the mine as an engineer
and eventually became General Manager of Malakoff Diggins under the NBGMC.
(Smith, 1871; NBGMC, 1876, 1877). There are also plans, logs, and receipts from
Malakoff Diggins operations (NBGMC, 1872a, b, 1898a, b). Josiah Dwight Whitney was
a California State Geologist who studied the geology of California as part of the
California Geological Survey (Whitney, 1880). Charles F. Hoffman was a geographer
who was part of Whitney's group and created a map of Malakoff Diggins containing
Humbug Creek, the auriferous gravel, mine claims, tunnels, ditches, roads and reservoirs
(Hoffman, 1872).
Waldemar Lindgren worked for the USGS and created geological maps of the
Colfax quadrangle (Lindgren and Walcott, 1900). Lindgren (1911) gives a detailed
account of the topography of the bedrock and the auriferous gravel deposits in a later
work.
The most recent geological maps of the Chico Quadrangle which includes
Malakoff Diggins were compiled by the California Department of Conservation –
Division of Mines and Geology (Saucedo et al., 1992).
After California Department of Parks and Recreation acquired Malakoff
Diggins, many studies were conducted to assess the site after the California Department
of Fish and Game raised concerns about the turbid water impacting fisheries. Jackson
(1967) studied and compiled historical accounts of Malakoff Diggins. The rate of erosion
was studied by Bouslog et al. (1977) and in master thesis's (Peterson, 1976; Yuan, 1979).
21
The Nevada County Resource Conservation District (NCRCD) conducted
studies as part of a management plan to reduce sediment from Malakoff Diggins State
Historic Park (NCRCD, 1979a). As part of the NCRCD Phase II study, water quality was
monitored from June 1978 to April of 1979 (NCRCD, 1979a). The water quality
parameters studied were, pH, dissolved oxygen, hardness, discharge, particle size
distribution, and precipitation. Samples were taken downstream of Hiller Tunnel and
tested for metals (As, Cd, Cr, Cu, Fe, Mn, Ni, Zn, Pb, Ca, Mg, Na, K), alkalinity (CO32-,
HCO31-), common ions (SO42-, Cl-, F-) (NCRCD, 1979a). The NCRCD came to the
conclusion that the Hiller Tunnel water was not hazardous (NCRCD, 1979b); even
though, the fisheries report noted the poor water quality and low productivity of Humbug
Creek (NCRCD, 1979a). Mercury was not part of this study because Mercury has a low
solubility and there was little to no mercury found in filtered water samples (NCRCD,
1979b).
The USGS conducted more recent studies of the sediments at the Humbug
Creek-South Yuba River Confluence (Fleck et al., 2010; Marvin-DiPasquale et al., 2010).
The goal of the studies was to determine the impacts of mercury on the ecosystem and if
suction dredge mining could be used to remove mercury from tailings and sediments in
the Sierra Nevada (Fleck et al., 2010). To determine where the sediment originated
sediment samples were taken from the mouth of the North Bloomfield Tunnel and from
Shaft 5 along the Humbug Trail (Fleck et al., 2010). Total mercury was measured for
each sample. For grain size smaller than 0.063 mm the Hg concentration was 2,520 ng/g
at Shaft 5 (Table 6) and 137 ng/g at the mouth (Table 7) (Fleck et al., 2010).
22
The USGS findings and the lack of any prior comprehensive study of the
water quality in all the mine features including all the air shafts was needed to better
characterize the potential impact that Malakoff Diggins may have on the Humbug Creek
and South Yuba River watersheds.
Purpose
There were multiple purposes of this study: (1) To characterize the water
quality of existing mine features at Malakoff Diggins, (2) To determine if water quality
can be used to indicate water flow and connectivity of mine features and surface water,
and (3) to provide additional information that can help guide future remediation efforts at
Malakoff Diggins.
Where as the North Bloomfield and Hiller Tunnels are mine features that were
built to convey mine water from the site and are sources of surface water discharge from
Malakoff Diggins to nearby streams and rivers. The tunnels are sources of sediment and
dissolved metals to the South Yuba River Watershed. For purposes of the is study it was
assumed that, if mine features have similar water quality and are geographically close to
each other then there is a likely a physical connection between features, such as a
common source, or connection that would allow the water in the features to mix and
therefore be similar.
To accomplish the purpose of this study, water samples were analyzed from
the North Bloomfield Tunnel including air shafts and from Hiller Tunnel. Measurements
were taken of pH, temperature, conductivity, dissolved oxygen, and concentrations of
metals and ions in the standing water in the air shafts associated with the North
23
Bloomfield Tunnel. These analyses were used as a measure of water quality, and to
determine connectivity between sections of the tunnel, separated by blockages between
air shafts.
To determine if there was connectivity between the shallow groundwater in
the pit, the pond in the Pit, and the surface water discharge from Hiller Tunnel,
groundwater borings were installed near the inlet of Hiller Tunnel and ground water level
measurements and water quality samples were collected from these features.
The research questions include:
1. What are the groundwater levels and the water quality of the mine features at
Malakoff Diggins?
2. Do the groundwater levels and water quality from the mine features indicate
water flow connectivity?
3. To what extent do subsurface water and Diggins Pond contribute to water quality
at Hiller Tunnel.
4. What are the physical and chemical hazards of the North Bloomfield Tunnel.
5. Is there evidence of a connection between waters in the shafts and mouth of the
North Bloomfield Tunnel?
CHAPTER II
METHODS
The study was conducted in stages starting in January 2012 to April of 2013.
The stages included: (1) Locate all of the features of the North Bloomfield Tunnel, (2)
Characterize the North Bloomfield Tunnel for physical and chemical hazards, (3)
Characterize the Hiller Tunnel for physical and chemical hazards, (4) Analyze subsurface
water in the Pit to determine if ground water was affecting the surface waters in the Pit
and Hiller Tunnel, and (5) Analyze the data and find relationships between sites.
North Bloomfield Tunnel
Air Shaft Physical Measurements
Physical measurements were taken of the North Bloomfield Tunnel (Figure 4)
air shafts and opening at the mouth in order to gauge the physical state of the tunnel,
identify physical hazards, and select water sampling locations.
To identify the locations for the shafts of North Bloomfield Tunnel Google
Earth images were over laid with historical engineering maps specifically (NBGMC,
1872a, b) to find GPS coordinates. The shafts were located in the field using a Garmin
GPSmap 60CSx, Global Positioning System.
The surface dimensions of the located air shafts were measured. The width of
the shaft opening, near the ground surface was measured using a tape measure. A Water
24
25
Figure 4. North Bloomfield tunnel.
Note: The North Bloomfield Tunnel starts in the Pit and runs
approximately 7920 ft south along Humbug Creek. Tunnel features include
the month and 8 air shafts. Brown Line – Border of Malakoff Diggins SHP.
White Lines – Tunnels, White Dots – sampling points, shafts and tunnel
openings.
26
Level Indicator manufactured by Slope Indicator Co. Sounder (Model # 51690010) was
used to measure the distance from the ground surface to the surface of the water in the
shafts. The bottoms of the shafts were measured by using a small weight on the end of a
rope that was lowered into the shaft until it made contact with a solid surface. The length
of the rope was measured with a measuring tape as it was pulled out of the shaft to
determine the depth of the shaft from the ground surface. Elevation of the air shaft
openings were taken from the USGS National Elevation Dataset of the Western United
States at 1/3 arc second, 10 m intervals, since the area was too densely vegetated to
survey. GPS points and depth measurements were taken from the edge of the shafts
closest to Humbug Creek at ground surface.
North Bloomfield Tunnel Water
Quality Measurements
Physical measurements were taken of the standing water in the mine features
of the North Bloomfield Tunnel. Measurements were taken using a YSI 556Multimeter
for pH, temperature, dissolved oxygen and electrical conductivity. The probe of the YSI
was on a cord 14 ft, (4.3 m) long. At mine features that had stable footing near the
surface of the water the YSI probe was placed in the deepest part of the mine feature
attainable without endangering samplers and would keep the hand held interface of the
YSI above water. A bailer was used to draw water from the middle of the water column if
the water in the mine features was inaccessible with the YSI probe. Readings were taken
after the multimeter had a few minutes to stabilize. Measurements from Shaft 5 and the
Mouth of the North Bloomfield Tunnel were taken multiple times during the study to see
if conditions changed over time.
27
A Sink Fast Bailer, 1L (Model # SF16x36SCW) manufactured by Aqua Bailer
was used to collect grab samples from Shafts 2, 3, and 4 because water was not at the
ground surface. Waters from Shafts 2, 3, 4 were placed in open containers before taking
readings for pH, electrical conductivity, and temperature. Dissolved oxygen was not
measured because the water was exposed to air as it was drawn up in the bailer and in the
open container.
North Bloomfield Tunnel Water Grab
Samples
Grab samples were collected from all the air shafts that had standing water in
them. Grab samples were taken following a modified version of method EPA 1669 ultra
clean method often referred to as Clean Hands Dirty Hands (Brooks Rand Labs, 2013).
Where waters were easily accessible the sample bottles were tilted at approximately a 45
degree angle and placed in the water so that the mouth of the bottle was facing toward the
surface or upstream. During sampling care was taken to make sure water only flowed into
the bottle.
When the surface of the water was not accessible, the Clean Hands Dirty
Hands Method was modified for bailer uses. This was true for Shafts 2, 3, 4 and in the
borings. A bailer lowered into the water column after it had been rinsed with deionizer
water or a new bailer was used for each sample. The sampler designated as "dirty hands"
would use the bailer to draw up the water and would hold the bailer while "clean hands"
would place a small segment of tubing in the bottom of the bailer to transfer water from
the bailer to the bottle.
28
Samples were not field filtered. Samples were preserved in the field with 2%
HNO3 or placed in a cooler with blue ice and shipped overnight to appropriate
laboratories.
Hiller Tunnel
Hiller Tunnel was the most visible source of surface water discharge from the
Pit. Grab samples and measurements for pH, temperature, and electrical conductivity
were taken from outlet of Hiller Tunnel using the YSI multimeter probe.
Borings
Borings were installed in the Pit near the entrance of Hiller tunnel. Borings
were placed in a T-shaped array to look at subsurface water flow and chemistry around
Hiller tunnel (Figure 5). P-1 was approximately 60 ft north of the entrance of Hiller
tunnel. P-2 was approximately 200 ft west of P-1. P-3 was approximately 200 ft east of P1. P-4 was approximately 200 ft north of P-1 (Figure 5). Locations for borings were
chosen that were relatively free of flora in a 3 ft (1 m) radius and to a height of >10ft (3
m) and in the area of distinct surface water flow channels.
Borings were dug with a 3-inch diameter soil auger. The auger was marked
every foot and a ruler was used to confirm the depth. Sediment from varying depths were
placed in one-gallon zip lock bags and taken for analysis in other studies (Kathleen
Berry-Garret, pers. comm., 2013; Keith Landrum, pers. comm., 2013; Cami Liggett, pers.
comm., 2013).
Borings consist of 10-foot long sections of 2-inch diameter PVC pipe placed
~6 ft into the ground. The bottom 2 feet of the pipe PVC pipe was screened with
29
Figure 5. Locations of borings.
Note: Borings were placed near the entrance to Hiller Tunnel and are
approximately 200 ft from each other and screened at a depth of 4-6 ft. Blue
Dots – Boring locations, White Lines – Tunnels, White Dots – Tunnel
openings. Coordinates in Appendix A, Table A-2.
30
premanufactured 0.02-inch slots. Around the bottom of the PVC pipe approximately 2 ft
of sand was placed. Bentonite was placed to a depth of ~0.5 ft from where the PVC pipe
meets the ground. The area between the sand and bentonite was back filled with native
soil (Figure 6). End caps were attached without screws or glue to avoid interference with
Figure 6. Boring design.
Note: Borings were constructed by placing a 10 ft length of 2 inch diameter PVC pipe
into the ground to a depth of 6 ft. The bottom 2 feet of the boring were screened with
0.02 inch slits. The boring was backfilled with 2 ft of sand, 3.5 ft of sediment, and 0.5 ft
of bentonite. Brown – Sediment in the Pit, Tan – Sand, Grey – Bentonite, Blue – above
ground. Green – vegetation, Clustered Horizontal Lines – Screen
pressure transducers and chemical and metal contamination in the boring. All materials
were new. Borings were developed by drawing three boring volumes of water out of the
borings a week after the borings were installed. No samples were taken during well
development.
31
Boring Water Level
Water level was initially measured with a Water Level Indicator manufactured
by Slope Indicator Sounder. On 11/4/2012, pressure transducers (Global Water, Model
WL15-015) were placed in the borings and on the surface near the borings to measure
groundwater and surface water levels. The pressure transducers consisted of a probe that
was at the end of a capillary tube. At the other end of the capillary tube was a data logger
which also had a barometer to compensate for air pressure. Pressure transducers were set
to collect measurements every 15 minutes. The pressure transducer probes were placed
inside each of the borings. The data logger and the top of the boring were covered with
zip lock bags and secured with zip ties or duct tape to keep water out of the boring and
data logger.
Boring Measurements
Readings were taken for pH, electrical conductivity and temperature during
the 11/4/2013-3/21/2013 monitoring period, at week to month long intervals or during
storm events during the monitoring period.
A YSI 556 Multimeter was used to take readings from the borings in a similar
manner as described in the (North Bloomfield Tunnel Mine Feature Water Section) with
the following changes. The pressure transducer probe was removed from the boring
before using the bailer and replaced after all measurements and samples were taken. A
bailer was used to purge the boring of three boring volumes of water before taking water
quality measurements. Once the boring was purged, the probe from the YSI 556
Multimeter was placed at the bottom of the boring.
32
Boring Grab Samples
Grab Samples were taken from the borings before the rainy season to form a
baseline. Grab samples were taken periodically, during storm events, or with changes in
electrical conductivity and pH measured by monitoring the borings with the YSI 556
Multimeter.
Each time grab samples were taken the borings were purged of three boring
volumes of water using a bailer before collecting samples. After the well was purged
samples were taken the same way they were taken from Shaft 2, 3, 4 of the North
Bloomfield Tunnel using a bailer.
Laboratory Testing
Samples for total metal analysis were sent to BSK Laboratories and prepared
by method EPA 200.2 and tested by method EPA 200.7/200.8,and hardness calculated by
SM 2340B. Samples were collected in 250 ml HNO3 preserved plastic bottles. Samples
were stored at room temperature for up to 4 months before testing this was within the 6
month hold time for the methods use for total metal analysis.
Samples sent to BSK Laboratories for chloride, nitrate, and sulfate by method
EPA 300.0 and alkalinity by SM 2320B were collected in 500 ml non-preserved plastic
bottles. The non-preserved plastic bottles were placed in ice chests with ice or blue ice
before being sent overnight to BSK Laboratories.
Low-level mercury samples were sent to Brooks Rand LLC. Low-level
mercury samples were placed in 125 ml plastic bottles which were double bagged.
Samples were placed on ice or on blue ice before being sent over night to Brook Rand
33
LLC where they were received by the lab within the 24-hour hold time per method EPA
1631. Low-level mercury samples were tested for total mercury, and for dissolved
mercury. Total mercury samples were not filtered. Dissolved mercury samples were
filtered through a 0.45 µm filter at the lab before analysis. The difference between the
concentration of total mercury and dissolved mercury is the mercury that is associated
with particulates and sediment that was filtered out.
Data Analysis
Water quality measurements were graphed to determine if there was a change
in the parameters between sampling periods. Data from North Bloomfield Tunnel
features were graphed as water quality parameters distance from the Pit to determine if
there was a trend with distance from the Pit. Bar graphs were used to compare the
concentrations of constituents from each feature, North Bloomfield Tunnel, Hiller
Tunnel, and shallow groundwater borings.
Principle component analysis (PCA) was used on the dataset and a biplot was
created to find relationships between samples. A biplot was used to graph samples based
on a large number of variables, specifically the metal concentrations in each sample. The
purpose of the PCA and biplot is to visually organize large datasets to find samples that
are outliers or form groups.
Biplots can display large amounts of information in a small space (Figure 7).
The axis of a biplot are based on the principle components with the greatest variance.
Each arrow radiating from the center or loading represents a variable. The
distance of the loading from the center represents how much a loading varies. Lines that
34
Figure 7. Explanation of biplot.
have smaller angles between them correlate more closely to one another. Lines that are
90° apart have no correlation and those that are 180° apart have an inverse relationship.
Points represent sampling sites. Points which are near the center have average amounts of
the variable. Points further away from the origin have larger amounts of the variable if
they are distant from the center in the same direction as the loading arrow.
Analysis of variance (ANOVA) was used on the dataset to study the variance
in the data between sample locations and between the constituents analyzed. The data
35
from an ANOVA is displayed in a matrix. The first column is the Sum of Squares which
is the difference between the value of a sample and the mean of the value squared and
then summed for all samples. The second column is the degrees of freedom. The Third
column is the mean square. The fourth column has the F-value from a F-test performed
on the data. An F-test is used to test if the variance between samples is equal or not. If the
F-value is above the F-critical, in the sixth column, then the variances are not equal based
on a 5% level of significance. The fifth column contains the P-value. If the P-value is
below 0.05 then the means of the samples are not equal based on a 5% level of
significance.
A correlation matrix was created to find the correlation between samples and
between constituents. If the correlation is above 0.95 then there is a statistically
significance direct relationship between values. If there is 0 correlation then there is no
relationship between values, and if the value is near -1 then there is an inverse
relationship between the values.
CHAPTER III
RESULTS
Precipitation
There was lower than average rainfall during the 2012/2013 rainy season
(NWS, 2013). There were three large storms in November and December that dropped up
to 2.36 inches of rain in a single day on November 17, 2012 (Weather Underground,
2013). January and February were the driest since 1920 (Thomas, 2013). There were
some small storms in March. Precipitation data (Figure 8) are from B-4 Ranch Weather
Station which is located 5 mile southeast of Malakoff Diggins from 10/1/2012 to
4/15/2012 monitoring period (Weather Underground, 2013). The total rainfall during the
10/1/2012 to 4/15/2012 monitoring period was 26.65 in. (Weather Underground, 2013).
The North Bloomfield Tunnel runs approximately 7920 ft from the Malakoff
Diggins Pit due South along Humbug Creek. The tunnel has eight air shafts that are at
approximately 1,000 ft intervals along the length of the tunnel and extend vertical into the
ground surface. The Mouth was the lowest point in the North Bloomfield Tunnel. The
tunnel was constructed so that each air shaft extends approximately 200 ft below ground.
The tunnel slopes downward heading of the Pit with a total elevation loss of 365 ft. Shaft
36
37
Figure 8. Precipitation for the 10/1/2012 - 4/15/2012 monitoring period.
Note: Blue line represents daily rainfall. Specific storm events are noted in Appendix
A, Table A-1.
Source: Data for figure from Weather Underground, 2013, History for
KCANEVAD14: http://www.wunderground.com/weatherstation/
WXDailyHistory.asp?ID=KCANEVAD14&graphspan=custom&month=1&day=1&year
=2012&monthend=6&dayend=16&yearend=2012 (accessed May 2013).
2 and 4 were located using longitude and latitude coordinates found by overlaying
(NBGMC, 1872a, b) over Google Earth (Figure 9). The coordinates were found in the
field using a GPS on 9/2/2012 and actual locations were noted (Table 1).
Shaft 7 and 8 were not found. Locations for Shafts 7 and 8 were determined
from historic maps of Malakoff Diggins (Figure 9) (NBGMC, 1872a, b). Shaft 8 is likely
located in the Pit north of the entrance to Hiller Tunnel. Shaft 8 was most likely filled in
during the landslides that happened during the 1930’s (Jackson, 1967). Since Shaft 8 was
the main drainage for the Pit during operations water subsequently filled the Pit after the
1930s collapse (Jackson, 1967). Shaft 7 is likely located northwest of the trailhead for
38
Figure 9. Locations of mouth and shafts of North Bloomfield Tunnel from Google Earth.
Note – This is the Google Earth overlay used to find the locations of the shafts of North
Bloomfield Tunnel.
Source: Locations plotted from North Bloomfield Gravel Mining Company, 1872a,
Plan of Bloomfield Tunnel and gravel mines owned by North Bloomfield Gravel Mining
Company, Nevada County, Cal: San Francisco, California [?], North Bloomfield Gravel
Mining Company, scale 1:24 000, 1 sheet. [Bancroft Library Collection and California
Society of Pioneers]; North Bloomfield Gravel Mining Company, 1872b, Plan of North
Bloomfield Gravel Mining Company and several locations for a bedrock tunnel bottom
deep gravel, Spring Valley Water Company, 1872, scale 1:9600. [Bancroft Library
Collection].
39
TABLE 1. LOCATION OF MOUTH AND SHAFTS OF THE NORTH BLOOMFIELD
TUNNEL
Site
Location
Surface
Water
Bottom
elevation
elevation
elevation
Lat.
Long.
Error
(ft)
(ft)
(ft)
(°N)
(°W)
Mouth
39° 20.923' 120° 55.591' ± 20 ft
Shaft 1
39° 21.159' 120° 55.481'
± 9 ft
Shaft 2
39° 21.296' 120° 55.423' ± 32 ft
Shaft 3
39° 21.439' 120° 55.354' ± 12 ft
Shaft 4
39° 21.591' 120° 55.341' ± 11 ft
Shaft 5
39° 21.730' 120° 55.329' ± 16 ft
Shaft 6
39° 21.884' 120° 55.333' ± 16 ft
Shaft 7* 39° 22.023' 120° 55.300'
Shaft 8* 39° 22.173' 120° 55.322'
Note: Locations of Shaft 7 and 8 are theoretical
2504
2758
2798
2849
2862
2883
2960
3015
3022
2504
2750.5
2754.2
2821
2817.3
2883
2957
2504
2745.5
2682
2791
2697.7
2807
2956
Hiller Tunnel along North Bloomfield Rd. Shaft 7 was difficult to access because it was
overgrown by manzanita. Shaft 7 could have been filled from construction of the North
Bloomfield Rd. and the turn out on the road for the trail to Hiller Tunnel.
Shaft 6 was 962 ft (293 m) south of the theoretical location of Shaft 7
(NBGMC, 1872a, b). Shaft 6 was on the uphill or west side of Humbug Creek Trail.
Shaft 6 was mostly filled in and was 3 ft (1 m) deep. Shaft 6 was easily accessible and
was next to the Humbug Creek Trail. A wire fence blocks access to Shaft 6 from the
Humbug Creek Trail.
Though there was perpetual water in Shaft 6 there was no observable
discharge from the shaft and the water level did not appear to change from January of
2012 to March of 2013. The water in Shaft 6 was green and hydrous ferrous oxide floats
on the surface of the water and on submerged solid surfaces. The walls surrounding the
opening of Shaft 6 are composed of loose red dirt which erodes into the shaft opening.
40
Shaft 5 is 904 ft (276 m) south of Shaft 6 on west side of the Humbug Creek
Trail (NBGMC, 1872a, b). Shaft 5 is 76 ft (23 m) deep and 17.4 ft (5.3 m) in diameter.
Shaft 5 was easy to access from the trail and surrounded by a wire fence.
The water in Shaft 5 has color that varies over time from green and red to
colorless. Shaft 5 was the only air shaft that had visible discharge into Humbug Creek.
The discharge was continuous and flows over the trail and hillside into Humbug Creek at
approximately 0.3 cfs (The Sierra Fund, 2013). The discharged water flows under a foot
bridge on the Humbug Creek Trail. The area the discharged water flows over was
covered with hydrous ferrous oxide. The sides of Shaft 5 are composed of exposed
bedrock.
Shaft 4 was 889 ft (271 m) south of Shaft 5 (NBGMC, 1872a, b). Shaft 4 was
directly east of the exploration campground on the Humbug Creek Trail. Shaft 4 was the
only shaft on the eastside of Humbug Creek. Shaft 4 was on an old road or terrace
approximately 100 ft from Humbug Creek. Shaft 4 was difficult to access because of the
Humbug Creek crossing and there was no trail to the shaft.
The opening of Shaft 4 was about 40 ft (12 m) above Humbug Creek
(NBGMC, 1872a, b). The diameter of the shaft was 15 ft (4.6 m) at the surface and the
top 10 ft (3 m) of Shaft 4 has partially eroded. The erosion occurred after a wire fence
was placed, because some of the posts are no longer rooted in the ground and hang over
the shaft opening, while other posts have fallen over. Below 10 ft (3 m) the bedrock
which composes the shaft walls is still in good condition and the shaft is rectangular.
Shaft 4 is surrounded by old rusty mining equipment, and many trees.
41
Shaft 3 was 907 ft (276 m) south of Shaft 4 and was next to the Humbug
Creek Trail on the down slope or east side of the trail (NBGMC, 1872a, b). Shaft 3 was
17.4 ft (5.30 m) in diameter, and a wire fence surrounds the opening of Shaft 3.
The upper portion of Shaft 3 consists of loose soil which has partially
collapsed into the shaft along with some trees. Trees grow around the top of Shaft 3. The
lower portion of the shaft consists of rock.
Shaft 2 was 906 ft (276 m) due south of Shaft 3 on the west bank of Humbug
Creek (NBGMC, 1872a, b). Shaft 2 was on a hillside between the Humbug Creek Trail
and Humbug Creek approximately 100 ft (30 m) south of where the Humbug Creek Trail
meets an abandoned road which leads to Lake City. The lip of Shaft 2 was approximately
20 ft above Humbug Creek. Shaft 2 was not visible from the Humbug Creek Trail and
was difficult to access because there was no trail to Shaft 2. Shaft 2 was surrounded by a
wire fence.
The walls of the Shaft 2 consist of bedrock and the shaft had a rectangular
shape. Trees grew around the top of the shaft. Ground water drips in from the sides of the
shaft though there was no water coming into the shaft from the surface.
Shaft 1 was 929 ft (283 m) south of Shaft 2 (NBGMC, 1872a, b). Shaft 1
looks like a pond that lies approximately 10ft (3 m) from Humbug Creek and was
between Humbug Creek and the Humbug Creek Trail. Shaft 1 was 16 ft (4.9 m) deep and
68.5 ft (20.9 m) in diameter.
The area around Shaft 1 consists of unconsolidated sediment and the water in
the shaft was black and turbid. The characteristics of the shaft are consistent with the
description of loose soil making up the top 72 ft of the shaft (Jackson, 1967), and the
42
collapse of the Shaft 1 documented in the 1930s, “Moreover, No. 1 shaft of the tunnel,
down on Humbug Creek, also caved in” (Jackson, 1967, p. 126).
The Mouth was 1,509 ft (459 m) south of Shaft 1(NBGMC, 1872a, b). The
walls of the Mouth are composed of bedrock. Water flows out of the Mouth and a spring
flows into the mouth from the western side of the Mouth. The water from the Mouth
discharges into Humbug Creek. Though the water was colorless, hydrous ferrous oxides
covered solid surfaces over which the water flowed. The hydrous ferrous oxide increases
in depth further into the tunnel eventually filling the tunnel and make it impossible to
pass approximately 1,000 ft (304.8 m) into the tunnel (John Lane, pers. comm., 2012).
Willows grow in the area between the Mouth and Humbug Creek.
From the measurements taken of the shafts a conceptual model was created
(Figure 10). To create the conceptual model measurements were taken from the depth
from ground surface, to the bottom of the shaft and to the surface of standing water for
Shaft 6, 5, 3 and 1 on 2/24/2012 and from Shaft 2 and 4 on 3/21/2013. Profile was taken
from Google Earth and elevation was measured by mapping the points on the USGS
National Elevation Dataset (USGS, 2013). The location of the tunnel is based on
(NBGMC, 1872a, b). Elevation was combined with measurements taken in the field to
determine approximate relative the water elevation in the shafts.
North Bloomfield Tunnel Feature
Water Measurements
The water from the shafts were measured for temperature, electrical
conductivity and pH, on multiple occasions between 3/26/2012 and 3/10/2013. Shafts 2,
Figure 10. Conceptual model for the hydrology of North Bloomfield Tunnel.
Note: The conceptual model represents the condition of the North Bloomfield Tunnel based on our current understanding.
Brown Line – Ground surface, Black – North Bloomfield Tunnel, White – Sky, Pink – Earth, Blue – Water
43
44
3, and 4 were measured once because they were difficult to access, requiring a pulley
system to take samples.
The pH from all the shafts (Figure 11) ranged from 8.28 to 5.92. The electrical
conductivity (Figure 11) in the Mouth, Shaft 1, 2, 3 and 4 ranged from 0.584 ms/cm2 at
the Mouth to 0.202 ms/cm2 at Shaft 3. Shafts 5 and 6 had conductivities of 1.149 ms/cm2
and 1.087 ms/cm2 respectively. The water temperature in the air shafts (Figure 11)
fluctuated from 5.66 °C at Shaft 1 to 11.19 °C at Shaft 5.
North Bloomfield Tunnel Grab Samples
Samples were collected from the mouth on 3/9/2012. Grab samples were
gathered from Shaft 1, 3, 4, 5, and Diggins Pond on 3/26/2012, which was late in the
rainy season. Grab samples were taken from Shafts 2 and 4 on 11/9/2012 at the start of
the rainy season during the first snow. Grab samples were not field filtered, therefore,
they represent total metals which includes particulate material. Dissolved metals were not
measured.
Metals. The concentrations of most trace metals were low in the Shafts and
the Mouth (Figures 12 and Figure 13) when compared to other sites at Malakoff Diggins.
The highest As (5 µg/L), Zn (150µg/L), Ni (180µg/L) and Cr (2.1 µg/L) concentrations
were at Shaft 5. The highest Pb (6.5 µg/L) and Cu (5.4 µg/L) concentration were at Shaft
4. The highest Ba (87 µg/L) concentration was at the Mouth of North Bloomfield Tunnel.
The following metals were tested but were below reporting limits for all shafts for
Sb<0.50 µg/L, Be <0.50 µg/L, Cd <1.0µg/L, Se <2.0µg/L, Ag <0.25 µg/L, Tl<1.0 µg/L.
Samples from Shafts 2, 3 and 4 were below reporting limits for Ba <5.0µg/L, Zn
<10µg/L, Ni <1 µg/L.
45
Figure 11. Average electrical conductivity (EC), pH and temperature of standing water
in the mouth and shafts of the North Bloomfield Tunnel.
Note: North Bloomfield Tunnel mine feature data collected from 3/26/2012 to
3/10/2013 and features were not measured an equal number of times.
Blue Diamonds – pH, Red Squares – Electrical Conductivity, Green Circles –
Temperature.
46
Figure 12. As, Cr, Cu, and Pb in North Bloomfield Tunnel.
Note: As, Cr, Cu and Pb were measured for all samples. If a site does not have a
column for a metal then it was below reporting limits. Columns with values below 1 µg/L
are labeled. The reporting limits: As <2.0 µg/L, Cr <0.50 µg/L, Cu <0.50 µg/L, Pb < 0.50
µg/L. All values are in Appendix A, Table A-7.
Common Ions, Hardness and Alkalinity. Hardness was relatively high in all
the shafts. There were high concentrations of sulfate in the Mouth (89 mg/L), Shaft 5
(150 mg/L) and Shaft 6 (130 mg/L) (Figure 14). Sulfate (SO42-) was below reporting
limits in Shaft 1. The alkalinity was lowest in Shaft 3 (33 mg/L) and highest in Shaft 2
(160 mg/L), Shaft 4 (120 mg/L) and Mouth (100 mg/L). Chlorine (Cl-) and nitrate (NO3-)
were not measured for Shaft 2 and 4.
47
Figure 13. Ba, Zn and Ni in North Bloomfield Tunnel.
Note: Ba, Zn and Ni was measured for all samples. Values with no column were below
reporting limits. Columns with values below 1 µg/L are labeled. Reporting limits: Ba < 5
µg/L, Zn < 10 µg/L, Ni <1 µg/L. All values are available on in Appendix A, Table A-7.
Hiller Tunnel
Hiller Tunnel Measurements
The temperature of water in Hiller Tunnel changed seasonally (Figure 15).
Electrical conductivity was high (1.154 ms/cm2) during the dry season and low during the
rainy season, never exceeding 0.196 ms/cm2 (Figure 16). The pH ranged from pH 7.3 at
the exit of Hiller Tunnel on 1/11/2013(day after small storm) to pH 5.96 on 12/2/2013
(large storm) (Figure 17). The pH between the entrance and exit of Hiller Tunnel varied
from a pH of 0.15 on 11/20/2012 to a pH of 0.43 on 1/11/2013. The water from Hiller
Tunnel was fully saturated with dissolved oxygen averaging 13.6 mg/L at the exit.
48
Figure 14. Constituents of mouth and shafts in mg/L.
Note: Chlorine is missing from Shaft 2 and 4 because it was not measured at Shafts 2
and 4. Other constituents without columns were measured and were below reporting
limits. Columns with values below 10 mg/L and 1 mg/L are labeled in respective graphs.
Reporting Limits – SO42- <4.0 mg/L, Alkalinity <3.0 mg/L, Ca <0.10 mg/L, Fe < 0.050
mg/L, Al <0.050 mg/L, Mg <0.10 mg/L, Mn <0.010 mg/L, Cl < 1.0 mg/L. All values are
available on in Appendix A, Table A-7.
49
Figure 15. Temperature change in Hiller Tunnel.
Note: Blue line – average daily temperature. Orange Square – Measurements taken
from the inlet or entrance to Hiller Tunnel. Grey Square – Measurements taken from the
outlet or exit of Hiller Tunnel.
Figure 16. pH Change of Hiller Tunnel.
50
Figure 17. Conductivity change of Hiller Tunnel.
Note: Values for Conductivity, pH and temperature are in Appendix A, Table A-4.
Precipitation measured in inches per day.
Hiller Tunnel Grab Samples
Grab samples were taken from the exit of Hiller Tunnel on 1/20/2013,
1/23/2013, 127/2013, 3/27/2012 and 11/4/2012 (Figures 18, 19, 20). Data were added
from Diggins Pond because Diggins Pond is a tributary to the water in Hiller Tunnel.
Dissolved metals were not measured.
The highest concentrations of Ba (230 µg/L), Zn (130 µg/L), Ni (110 µg/L),
Cr (76 µg/L), Cu (130 µg/L), Fe (39 mg/L) and Al (39 mg/L) from Hiller Tunnel were on
3/27/2012 (1.09 inches) which was during the middle of a storm. The highest
concentration of Pb (23 µg/L) in Hiller Tunnel was on 1/23/2012 (0 inches) after a storm.
The highest concentration of Mn (1.4 mg/L) was on 1/20/2012 (2.60 inches) during a
large storm and 11/4/2013 (0 inches) a few days after a storm. The concentrations in
51
Figure 18. Trace metals in Hiller Tunnel and Diggins Pond.
Note: Measurements were taken for all constituents graphed for all samples. The
readings are highly variable columns not visible were very low or are below
reporting limits. Columns with values below 10 µg/L are labeled. Reporting
Limits: Cu <0.50 µg/L, Pb <0.50 µg/L, Cr <0.50 µg/L, Ni <1.0 µg/L, Zn <10 µg/L,
Ba < 5.0 µg/L. All values are available on in Appendix A, Table A-8.
Diggins Pond tended to be below those in Hiller Tunnel. The concentrations of Fe, Ca,
Mg and SO4 were only measured from Hiller Tunnel on 11/4/2012 and Diggins Pond on
3/26/2012.
Borings
Borings were installed in the Pit near the entrance of Hiller Tunnel on
9/30/2013, a warm sunny day before the rainy season started so the Pit was dry. When the
borings were dug, there was a redox transition zone where the sediment turned from tan
to grey. The transition zone was above the water table. The depth of the transition zone
was approximately 3.5 ft for boring P-1 and 2, 5 ft for P-3 and 2.5 ft for P-4.
52
Figure 19. Fe, Al, and Mn in Hiller Tunnel and Diggins Pond.
Note: The measurements from Hiller Tunnel were highly variable. Readings were taken
from all constituents measured for all samples. Columns with values below 5 mg/L are
labeled. Reporting limits: Fe < 0.050 mg/L, Al < 0.050 mg/L, Mn < 0.010 mg/L. All
values are available on in Appendix A, Table A-8.
Boring Water Level
Boring P-3 went from dry to full from 4:00 am to 10:00 am on 11/17/2012
and P-1 and P-2 were also filled during this time (Figure 21). The precipitation measured
on 11/17/2012 was 2.36 inches in one day, which was the greatest precipitation in one
day during the monitoring period from 10/1/2012-3/21/2013. Before 11/17/2012, there
were smaller storm events starting on 10/22/2012 (Figure 8) and the total precipitation
from 10/1/2012 to 11/17/2012 was 3.43 inches. The period from 4:00 am to 10:00 am is
considered the boring wet up period from wells P-1, 2, and 3.
During the rest of the monitoring period after the wet up period 11/17/2012
through 3/21/2013 the water level in the borings and on the ground surface rose and fell
53
Figure 20. Fe, Ca, Mg and SO4 in Hiller Tunnel and Diggins Pond.
Note: Iron, Calcium, Magnesium, and Sulfate were only measured from Hiller Tunnel
on 11/4/2012 and from Diggins Pond on 3/26/2012. Columns with values below 10 mg/L
are labeled. Reporting Limits: Fe <0.050 mg/L, Ca <0.10 mg/L, Mg <0.10 mg/L, SO42<4.0 mg/L. All values are available on in Appendix A, Table A-8.
with precipitation (Figure 22). During the 12/2/2012 (2.26 inch) storm event in P-1 water
reached maximum height at 9:44 am (6 ft) while the water on the ground surface reached
its maximum height at 9:46 (0.73 ft).
During the first storm period on 11/17/2012 between 12:00 am and 10:00 am
there was 1.01 inches (25.7 mm).of rain. Assuming that there was no run off from areas
surrounding the Pit, the infiltration of water into the sediment in the bottom of the Pit
would be approximately (25.7 mm total/ 10 hour = 2.57 mm/hour). If there was runoff
from area surrounding the Pit the rate would be higher. The maximum rate that the
borings recharged on 11/17/2012 was 0.56 ft/hour (P-1), 1.48 ft/hour (P-2), 2.72 ft/hour
(P-3), and 0.08 ft/hour (P-4). After 11/17/12 the sediment in the Pit was fully saturated a
54
Figure 21. Boring wet up period
Note: Left Vertical Axis – Height of the water in the borings in feet (P-1 – Red Line, P2 – Green Line, P-3 – Black Line, P-4 – Purple Line). Right Vertical Axis – Precipitation
in inches/hour measured in 5-minute intervals from the B-4 Ranch Weather Station. This
is the rate of rainfall not the amount of rainfall during the 5-minute interval. Bottom
Right Corner – Map of Boring locations (P-1, P-2, P-3, P-4).
rough estimate of the storage capacity of the Pit is (3.43 inches + 1.01 inches = 4.44
inches of precipitation).
From Figure 21 an estimate can be made of the specific yield of the borings.
Specific yield is a measure used in hydrology for the amount of water than can be
pumped from a well. For the estimate of specific yield the following assumptions are
made: (1) Infiltration can be used in place of a pump test, (2) No water would be retained
55
Figure 22. Boring P-2 water height from bottom of boring, surface water, and
precipitation.
in the system after a pump test or that the water that would be retained would be roughly
equal to the water in the system before the ground was saturated, (3) there was 1.01
inches of rain before the ground was saturated on 11/17/2012 (4) the ground was
saturated by 10:00 am, and (5) there was no rain water runoff into the area around the
borings from surrounding areas. The time period calculated for is between 12:00 am and
10:00 am on 11/17/2012. The specific yield was calculated by the following formula.


Percipitation
SpecificYeild %  100  

 Water ElevationChangein Boring 
56
The specific yield was calculated for borings P-1, 2 and 3 (Table 2). It was not
calculated for boring P-4 because it was saturated before 11/17/2012.
Boring
P-1
P-2
P-3
TABLE 2. SPECIFIC YIELD OF BORINGS
Water level
Water level
Increase on
Increase on
11/17/2012 by
11/17/2012 by
Precipitation by
10 am (ft)
10 am (inches)
10 am (inches)
1.84
22.1
1.01
1.39
16.7
1.01
3.75
45.0
1.01
Specific Yield
(%)
4.57
6.06
2.24
Boring Water Quality Measurements
Readings of water quality (pH, electrical conductivity, and temperature) were
taken on 10/12/2012, 10/20/2012, 11/4/2012, 11/9/2012, 11/20/2012, 12/2/2012,
12/14/2012, 1/11/2012, 2/9/2013, 3/1/2013, and 3/9/2013. Readings were taken less often
during January and February because there was little rain (2.04 inches) and the surface
conditions changed little. Water chemistry was expected to change more quickly during
wet periods than during the January/February dry period. The temperature of the borings
decreased during the fall reaching their minimum on 3/1/2013 before rising again (Figure
23).
The lowest pH measured in the borings was 3.62 for P-1 on 12/2/2012, during
a large storm event (Appendix A, Table A-1). The other borings had pH between 5.81
and 6.84 on 12/2/2012. The highest pH (9.19) was measured from P-2 on 11/9/2012. At
other times the pH ranged from 7.55 to 5.4 (Figure 24).
The initial conductivity readings on 10/12/2012 were high at all of the borings
ranging from 1.483 ms/cm2 at P-4 to 0.689ms/cm2 at P-2 (Figure 25). After 10/12/2012,
57
Figure 23. Temperature changes in borings.
Note: Bottom Right – Map of Boring locations (P-1, P-2, P-3, P-4), Blue line – Average
Daily Temperature measured from the B-4 Ranch weather station. All values are
available on in Appendix A, Table A-5.
Figure 24. Changes over time pH.
Note:- Left Vertical Axis – Boring pH (P-1 – Blue dot, P-2 – Red dot, P-3 – Green dot,
P-4 – Purple dot). Right Vertical Axis – Precipitation in inches/daily. Bottom Right –
Map of Boring locations (P-1, P-2, P-3, P-4). All values are available on in Appendix A,
Table A-5.
58
Figure 25. Conductivity changes in borings over time.
Note: Left Vertical Axis – Electrical Conductivity of boring water (P-1 – Blue dot, P-2
– Red dot, P-3 – Green dot, P-4 – Purple dot). Right Vertical Axis – Precipitation
measured in inches/day. Bottom Right – Map of Boring locations (P-1, P-2, P-3, P-4). All
values are available on in Appendix A, Table A-5.
the readings decreased and ranged from 0.630 ms/cm2 on 1/11/2013 at P-1 to 0.256
ms/cm2 at P-4 on 3/21/2013. Boring P-3 had relatively high conductivity compared to the
other borings ranging from 1.656 ms/cm2 on 1/11/2013 to 0.998 ms/cm2 on 3/1/2013.
Boring Grab Samples
Grab Samples were initially taken from the borings P-1, P-2, and P-4 on
11/4/2012, and from boring P-1 and P-3 on 12/2/2012. Grab Samples from 11/4/2013 and
12/2/2013 were tested for Title 22 metals and SO42-. The data from the initial samples
taken on 11/4/2012, before the rain season had started, were compared to samples taken
on 12/2/2012, after a storm event, to determine criteria for metals analyzed in further
sampling. The criteria were (1) metals that had concentrations above reporting limits for
59
3 of the 4 borings and (2) showed a noticeable concentration difference between P-1
samples on 11/4/2012 and 12/2/2012. The metals that fit both criteria were Al, Fe, Cu,
Ni, As, Cr, Pb, and Zn.
Boring Trace Metals
The first set of samples from boring P-1, P-2, and P-3 tended to have higher
concentrations of metals than at P-4 or Hiller Tunnel (Figure 26). The exception was for
total Ni which was highest in Hiller Tunnel (96 µg/L). Boring P-1 had the highest total
arsenic concentration (31 µg/L) which was much larger than the next highest at P-1 (8.2
µg/L). At boring P-4 and Hiller Tunnel Pb <0.50 µg/L, Cr <0.50 µg/L, Zn <10 µg/L, and
Be <0.50 µg/L were below reporting limits. Arsenic <2.0 µg/L was below reporting
limits in Hiller Tunnel.
Data from Hiller Tunnel and Diggins Pond are included in Figure 26 to
compare the shallow subsurface water in the borings to surface waters near the borings.
Hiller Tunnel data from 11/4/2012 is used because borings P-1, 2 and 4 were also
sampled on 11/4/2012. In general, the borings had higher total metal concentrations than
the surface water in the pond or in Hiller Tunnel.
Non Trace Metals and Sulfate
The concentrations of non trace metals and sulfate at P-3 on 12/2/2012—Na
(41 mg/L), Fe (170 mg/L), Mg (98 mg/L) and SO4 (380 mg/L)—tended to be higher than
P-1, P-2, P-4, Hiller Tunnel on 11/4/2012 and Diggins Pond on 3/26/2012 (Figures 27
and 28).
60
Note: Inset Bottom Right – Map of Boring locations (P-1, P-2, P-3, P-4).
Concentrations were measured for all metals graphed. Columns that are not visible were metals with
concentrations below reporting limits. Columns with values below 10 µg/L are labeled. Reporting limits:
Cu < 0.50 µg/L, Pb <0.50 µg/L, Cr < 0.50 µg/L, Ni <1.0 µg/L, Zn < 10 µg/L. All values are available on in
Appendix A Tables A-6 and A-7.
Note: The concentrations in the Borings were higher than those in Hiller Tunnel or Diggins Pond. All
samples graphed were measured for As and Be. Columns that do not appear are below reporting limits.
Columns with values below 5µg/L are labeled. Reporting limits: As <2.0 µg/L, Be <0.50 µg/L. All values
are available on in Appendix A Tables A-6 and A-7. Inset Top Right – Map of Boring locations (P-1, P-2,
P-3, P-4).
Figure 26. Trace metals in borings, Hiller Tunnel and Diggins Pond. The concentrations
in the borings were higher than those in Hiller Tunnel or Diggins Pond.
61
Figure 27. SO4, Fe, Ca, Mg, SO4 in Hiller Tunnel borings.
Note: Sodium and Potassium were not measured for Diggins Pond 3/36/2012. All other
constituents were measured for samples. Columns with values below 5 mg/L are labeled.
Columns that are missing were below reporting limits. Reporting limits: Al < 0.050
mg/L, Mn < 0.010 mg/L, K <2.0 mg/L, Na <1.0 mg/L. All values are available on in
Appendix A Tables A-6 and A-7. Top Right – Map of Boring locations (P-1, P-2, P-3, P-4)
Boring Seasonal Changes.
Grab samples were taken from the borings on 2/9/2013 which was during a
dry period in January and February, 3/9/2013, after a small storm event (0.62 in. on
3/6/2013) and 3/21/2013, after another small storm event (1.14 in. on 3/20/2013) (Figure
29). Zinc was below reporting limits (<10 µg/L) in P-1 on 12/2/2012. Lead <0.50µg/L,
Zinc <10 µg/L and Chromium <0.50 µg/L were below reporting limits in P-4 on
11/4/2012.
62
Figure 28. SO4, Al, Mn, K, Na in Hiller Tunnel borings.
Note: Columns with values below 10 mg/L are labeled. Reporting limits: Fe < 0.030
mg/L, Ca <0.10 mg/L, Mg <0.10 mg/L, SO42- <20 mg/L. All values are in Appendix A
Tables A-6 and A-7. Top Right – Map of Boring locations (P-1, P-2, P-3, P-4)
Low Level Mercury
Low-level Hg samples were taken from the Mouth of the North Bloomfield
Tunnel on 2/13/2012 when the mouth was undisturbed and 3/9/2012 when the mouth was
disturbed. Samples for low-level mercury were taken from Shaft 1, 3, 5, 6, and Diggins
Pond on 3/26/2012 after a storm (Appendix A, Table A-1). Samples for low-level
mercury were taken from Shaft 2 and 4 on 11/9/2012 during a small storm early in the
rainy season (Appendix A, Table A-1). The borings P-1 through 4 were sampled for lowlevel mercury on 3/22/2013 after a small storm event (Appendix A, Table A-1). Samples
for low-level mercury were taken from Hiller Tunnel on 2/13/2013 during a dry period.
Shafts 2 and 4 were not tested for dissolved low-level mercury, all other sampling
included total and dissolved concentrations of mercury.
Figure 29. Metal concentrations in borings from 11/4/2012 to 3/22/2013.
Note: The graphs are ordered from P-1 at the top to P-4 at the bottom and each is given
a letter A-D. For example, the graph for P-1 is Figure 29(A) and the graph for P-4 is
Figure 29(D). Columns are colored by date. Colors and dates are the same for all graphs
in Figure 29. Dark Blue – 11/4/2012, Red – 12/2/2012, Green – 2/9/2013, Purple3/9/2013, Teal – 3/22/2013
Figure 29(C) – Boring P-3 was not measured until there was standing water in it on
12/2/2012 so there is no column for 11/4/2012. Figure 29 (B) and (D) Boring P-2 and P-4
were not measured on 12/2/2012 so there is no column for them on 12/2/2012. All
constituents graphed were measured for all borings. Columns that are not visible were
blow reporting limits. All values are in Appendix A, Table A-9.
63
64
Total Hg concentration was highest at Shaft 5 (2270 ng/L) and the dissolved
mercury was 0.51 µg/L (Figure 30). Besides Shaft 5 all the other shafts had low total Hg
ranging from 25.5 ng/L at Shaft 6 to 0.49 ng/L at the Mouth (Figure 30). The borings had
elevated total Hg concentrations—P-1 295 ng/L, P-2 189 ng/L, P-3 574 ng/L, P-4 337
ng/L.
Figure 30. Total Hg in at Malakoff Diggins.
Note: The bar representing concentration for Shaft 5 extends outside of the range of this
graph. Actual value is displayed on the graph.
The dissolved Hg was lower than the Total Hg for all samples (Figure 31).
The highest concentration of dissolved Hg was at Hiller Tunnel (2.49 ng/L) and the
lowest was at boring P-1 (0.15 ng/L) (Figure 31).
65
Figure 31. Dissolved mercury at Malakoff Diggins.
Principle Component Analysis
Data from the Principle Component Analysis (PCA) are displayed in a biplot
(Figure 32). Component 1 has the greatest variance (6.5) and component 2 has the second
greatest variance (1) (Appendix A, Figure A-1). The letters after boring names represent
the times samples were taken at; a-11/4/2012, b-12/2/2012, c-2/9/2013, d-3/9/2012, e3/22/2013.
Cr, Pb, Cu, Zn, Al and Ni have a close direct correlation. Arsenic does not
correlate well with any of the other metals. The borings (P-1, P-2, P-3, P-4) were outliers
because they had metal concentrations that were larger than average. Borings P-1 and P-4
form a group because they had higher Cr, Pb, Cu, Zn, Al and Ni concentrations. Boring
P-3 is an outlier because of its high Ni concentrations. Boring P-2 was an outlier because
of its high concentrations of As.
66
-4
2
2
P-3d
P-3c
P-1d
P-4c
Al
Zn
Cu
Pb
Cr
P-4d
Hiller Tunnel
Sample
SiteS
Green
Bubble
Diggins
Po
5 Shaft
Spring
P-1c ShaftRed
P-3b
Shaft 6 31
P-1b
Shaft 4
P-1eP-4e
Mouth
Shaft2
P-4a
P-1a
0
0.2
0.0
0
P-3e
Ni
-2
-0.2
Fe
P-2d
P-2e
-4
-0.4
Comp.2
-2
As
-0.4
-0.2
P-2c
P-2a
0.0
0.2
Comp.1
Figure 32. Biplot of the waters of Malakoff Diggins based on metals concentration.
When more variables—metals, sulfate and alkalinity—are added to the PCA
of samples from Malakoff Diggins (Figure 33) more samples are outliers. Sulfate,
calcium and magnesium correlate well and have an almost inverse relationship to
alkalinity (HCO3-). The metal concentrations do not correlate to sulfate concentrations.
The borings are outliers in both biplots (Figure 32 and Figure 33), P-3 has high sulfate,
calcium and magnesium while P-1 and P-2 have high metal concentrations, and P-4 has
67
Figure 33. Biplot of waters at Malakoff Diggins based on metals, sulfate and
alkalinity.
low sulfate, calcium and magnesium. Shaft 5 and 6 samples form a group due to high
sulfate, calcium or magnesium concentrations. Hiller Tunnel is also an outlier due to
sulfate but less so than Shaft 5 and 6.
Analysis of Variance
Analysis of variance (ANOVA) is commonly used to study the variance in a
data set. The ANOVA of the data from Malakoff Diggins (Table 3) gives F values that
are above F critical which means that the variance is not equal between constituents, or
68
TABLE 3. ANOVA OF DATA AT MALAKOFF DIGGINS
Source of
Variation
P-value
F crit
SS
df
MS
F
10
9
-10
Constituent
7.41x10
18
4.12x10
5.500282
2.17x10
1.656175
10
9
Samples
2.04x10
11
1.85x10
2.476696
0.00628
1.83726
11
8
Error
1.48x10
198
7.49x10
11
Total
2.43x10
227
Note: SS – Sum of squares, df – degrees of freedom, MS – Mean square, F – F
statistic
samples. The P-values are below 0.05 for both constituents and samples; therefore, the
means between samples and constituents are not the same.
Correlation Matrix
A Correlation Matrix can be used to analyze the correlation between large sets
of data. Two correlation matrices were created from the data at Malakoff Diggins, one for
metals and common ions (Table 4) and one for the sites (Table 5). Values that are closer
to 1 mean that there is a direct correlation values near 0 mean that there is no correlation
and values that are closer to -1 have an inverse relationship.
The constituents analyzed that have significant correlation are Cr with Al,
Alkalinity with Ca, and Be with Cr, Cu, and Pb. The correlations that match the
correlations found in PCA are Be with Cr, Cu, and Pb, and Al with Cr. The PCA showed
that Ca and Alkalinity almost have an inverse correlation while the correlation matrix
shows that they have a positive correlation.
The shafts that correlate well are Shafts 2, 3 and 4. There is little correlation
between the other samples. Though they correlate well in terms of metal and common ion
concentration, there were other measurements taken that were not included in the
correlation matrix.
TABLE 4 CORRELATION MATRIX BETWEEN CONSTITUENTS
Al
Ca
Al
Ca
1.00
0.62
1.00
Fe
0.38
0.11
1.00
0.75
0.20
-0.32
0.70
0.51
-0.33
0.93
0.97
0.93
0.94
0.26
0.63
0.94
0.30
-0.08
0.97
-0.05
-0.03
0.36
0.45
0.38
0.42
0.22
0.37
0.16
0.63
0.29
0.11
0.55
0.48
0.50
0.47
0.49
0.46
0.54
0.48
Mg
Mn
SO4
Alkalinity
As
Ba
Be
Cr
Cu
Pb
Ni
Zn
Fe
Mg
Mn
SO4
Alkalinity
As
Ba
Be
Cr
Cu
Pb
Ni
Zn
1.00
0.34
-0.12
0.93
0.05
-0.12
0.51
0.60
0.52
0.53
0.30
0.47
1.00
0.80
0.15
0.33
0.42
0.20
0.23
0.19
0.17
0.70
0.66
1.00
-0.29
0.04
0.48
-0.25
-0.26
-0.26
-0.27
0.61
0.40
1.00
0.00
-0.15
0.47
0.55
0.49
0.52
0.11
0.32
1.00
-0.12
0.63
0.63
0.56
0.58
0.25
0.43
1.00
-0.31
-0.31
-0.34
-0.34
0.27
-0.04
1.00
0.99
0.99
0.98
0.28
0.66
1.00
0.98
0.98
0.28
0.66
1.00
0.98
0.30
0.66
1.00
0.26
0.66
1.00
0.74
1.00
Note: Yellow Highlight – Statistically Significant, Orange Highlight – close to being statistically significant.
69
TABLE 5 CORRELATION MATRIX BETWEEN SAMPLE SITES
Shaft
Shaft
Shaft
Shaft 1 Shaft 2 Shaft 3
Diggins P-1 P-2
4
5
6
Mouth
P-3 P-4
Mouth
0.95
Shaft 1
0.54
0.95
Shaft 2
0.47
0.89
0.95
Shaft 3
0.47
0.88
0.95
0.95
Shaft 4
0.47
0.87
0.95
0.95
0.95
Shaft 5
0.59
0.06
0.13
0.12
0.12
0.95
Shaft 6
0.62
0.32
0.43
0.41
0.41
0.66
0.95
Diggins
0.61
0.52
0.26
0.25
0.24
0.18
0.28
0.95
P-1
0.40
0.42
0.48
0.48
0.47
0.50
0.29
0.10
0.93
P-2
0.40
0.07
0.15
0.14
0.14
0.61
0.36
0.02
0.81 0.94
P-3
0.43
0.81
0.86
0.87
0.86
0.20
0.32
0.20
0.64 0.30 0.88
P-4
0.78
0.53
0.59
0.58
0.58
0.42
0.46
0.21
0.55 0.51 0.56 0.92
Hiller Tunnel 0.54 -0.05
0.05
0.04
0.04
0.75
0.49
0.12
0.21 0.36 0.06 0.40
Note: Yellow Highlight – Statistically Significant, Orange Highlight – close to being statistically significant.
Hiller
Tunnel
0.91
70
CHAPTER IV
DISCUSSION
The North Bloomfield Tunnel had varied water chemistries; therefore,
different processes could be dominating water chemistry at each air shaft. Shaft 5 and 6
both have similar water chemistries that differ from the water chemistries of the other
shafts (Figures 11-14). The pH, electrical conductivity, temperatures, Al, Mg, Mn, Cl,
NO3- , SO42-, Ca, Fe concentration and Alkalinity were similar and followed similar
patterns for both shafts. They differ when looking at concentration of trace metals As, Cr,
Cu, Pb, Ba, Zn and Ni. Shaft 5 has higher concentrations of all of these trace metals than
Shaft 6.
Visually the waters in Shaft 5 and Shaft 6 are similar. Though the water color
in Shaft 5 changes seasonally they both have hydrous ferrous oxide. The high Fe and
SO42- could be a sign of pyrite oxidation that would make the water in the shaft more
acidic and would correlate with the hydrous ferrous oxides on the sold surfaces. The high
calcium concentration and alkalinity could indicate the dissolution of carbonate minerals
which would increase the pH.
Since Shafts 5 and 6 neighbor each other and have similar water chemistries
they could have the same source of water or similar geology. Shaft 6 was higher in
71
72
elevation than Shaft 5 and that could be the reason why Shaft 5 discharges water while
Shaft 6 dose not discharge water. Shaft 5 is deeper (76 ft) than Shaft 6 (3 ft) (Table 1),
therefore, Shaft 5 could be fed by more sources of groundwater at depth while Shaft 6
would be fed by groundwater closer to the surface and precipitation would have a greater
impact on concentrations in Shaft 6 (Figures 12-14).
Shaft 5 and 6 are also on the same ridge. On the ridge above the shafts is an
area that was hydraulically mined and is on the same auriferous gravel channel as
Malakoff Diggins. The area on the ridge is noted as the New York claim in (NBGMC,
1872a, b) and (Hoffman, 1872). At the time of this study, there were standing pools of
water at the New York claim. The water from Shafts 5 and 6 could be derived from
subsurface flow impacted by the New York claim. If the water in the shafts were from the
New York claim it could also be the source of water with high metal concentrations.
The difference in trace metal concentration between Shaft 5 and 6 could be
due to the way the samples were gathered. The samples were both taken on 3/26/2012.
Samples in Shaft 5 were taken at a depth of 30 ft with a bailer and the samples in Shaft 6
were taken from the surface. At the surface conditions would be expected to be oxidizing
due to mixing with the atmosphere while conditions would be expected to be reducing at
depth because the water is isolated from the atmosphere and aerobic bacteria would use
up the dissolved oxygen in the water (Eby, 2004). Many metals form solid species under
oxidizing conditions, and aqueous species under reducing conditions (Eby, 2004). The
samples in Shaft 5 were collected at depth where the water was reducing. If conditions
were reducing there could be more aqueous metal species in the water, while samples in
73
Shaft 6 were collected at the surface where conditions are oxidizing, so the species could
have precipitated out of solution decreasing the total metal concentrations in water.
The highest total mercury concentration is from Shaft 5 (2,270 ng/L) which is
much higher than the concentration at any of the other mine features; the second highest
total mercury concentration was (574 ng/L) at boring P-3. Though the total mercury
concentration at Shaft 5 was high the dissolved mercury concentration at Shaft 5 (0.51
ng/L) was similar to other sites. This could be because Shaft 5 was the only shaft that
discharged water. The discharged water may mix the water suspending Hg in solution.
The USGS took low-level mercury samples from Shaft 5 on 1/13/2009 (Fleck
et al., 2010). The USGS took samples of solid material in the discharge of the shaft and
separated it based on grain size before measuring the mercury concentration of each size
fraction (Fleck et al., 2010). In the solid material with grain size smaller than 0.063 mm
the Hg concentration was 2,520 ng/g (Fleck et al., 2010) (Table 6).
TABLE 6. SOLID SAMPLES FROM FLECK ET AL. 2010 AND WATER SAMPLES
FROM THE MOUTH ON 2/13/2012 AND SHAFT 5 ON 3/26/2012
Site
Sediment
Water
size (mm)
weight (%) THg (ng/g)
THg (ng/L)
NBT air shaft
0.25-1.0
0
0
surface sediment
.063-0.25
0
0
<0.063
32.9
2,520
2270
Since the concentration of Hg in filtered samples was much lower than in
unfiltered samples, most of the Hg was probably part of or absorbed on to the solid
material.
74
The high metal concentrations in samples from the North Bloomfield Tunnel
could be a legacy of historic mining practices. While Malakoff Diggins was in operation
blocks were placed on the bottom of the North Bloomfield Tunnel in 1,900 ft of the
tunnel between Shaft 8 and Shaft 6 to act as riffles to collect gold from the slurry flowing
through the tunnel (NBGMC, 1872a, b; Jackson, 1967). Mercury was placed in this
portion of the North Bloomfield Tunnel and on the surface of the Pit before the surface
was washed into the North Bloomfield Tunnel (Jackson, 1967).
Shafts 2, 3 and 4 are physically similar, with shafts over 50 ft deep from the
surface and partially filled with water. The water elevation in Shaft 3 and 4 was similar to
the elevation of Humbug Creek adjacent to the shafts. The water elevation of Shaft 2 was
below that of Humbug Creek adjacent to the shaft. Shaft 4 was the only shaft on the east
side of the Humbug Creek. From water elevation alone the water in Shafts 2, 3, and 4
could be from Humbug Creek
The pH of Shafts 2 (pH 8.28) and 4 (pH 8.97) are more basic than any of the
other shafts. This could be due to the high alkalinity in Shaft 2 and 4 (160 mg/L HCO3and 120 mg/L HCO3-respectively) which is higher than the alkalinity at any of the other
shafts (Figure 14). The high pH and alkalinity could be due to the dissolution of
carbonate minerals in the rocks around Shaft 2 and 4. The carbonate mineral marble
(CaCO3) was noted by Peterson (1976) in the bedrock.
The temperature and conductivity of Shaft 2, 3, and 4 are similar (Figure 11).
Shaft 2, 3 and 4 have similar patterns for SO42-, Ca, Mn, Mg, Ba, Ni, Cu and Zn with
Shaft 2 having the highest concentrations followed by Shaft 4 and Shaft 3 (Figures 12, 13
and 14). Shaft 4 had higher iron concentrations than Shaft 2 and 3.
75
Cr, Pb, and As do not follow the pattern of the other metals at Shaft 2, 3 and 4.
Shaft 4 has the highest concentrations of Cu (5.4 µg/L) and Pb (6.5 µg/L) of any of the
Shaft in the North Bloomfield Tunnel. Shaft 3 had some Pb (0.69µg/L) and Shaft 2 had
Pb concentrations below reporting limits. In Shaft 2, 3 and 4 only Shaft 2 had arsenic
concentrations above reporting limits.
Shafts 2, 3, and 4 have some similarities, such as temperature and
conductivity (Figure 11). Their similarities are supported by their close correlation in the
correlation matrix (Table 5). There are still many differences in As, Cu, Cr, Pb
concentrations, and pH. More work would have to be done to conclusively determine if
the waters in Shafts 2, 3, and 4 were connected or had a common source.
Shaft 1 has different physical dimensions and is visually different from the
rest of the shafts. Shaft 1 is a large pond that was only separated from Humbug Creek by
a small berm and the water elevation in the pond appeared to be the same elevation as
Humbug Creek. Due to Shaft 1's proximity to Humbug Creek and the water level,
Humbug Creek should be the main source of water for Shaft 1.
The concentrations in Humbug Creek are much higher than those in Shaft 1.
Due to the difference in concentration the water in Shaft 1 could be from a source other
than Humbug Creek. Another explanation is that the high concentrations in Humbug
Creek are due to suspended solids and particulate matter since those samples were taken
during storm event when creek water was turbid and full of suspended solids. As the
water goes through the berm separating Shaft 1 from Humbug Creek the solids could be
filtered out in addition the water in Shaft 1 is stagnant so particulates could settle out of
solution decreasing the concentration from suspended particulates.
76
Shaft 1 had turbid black water probably due to organic material decomposing
in the shaft; therefore, it was expected to have different water chemistry from the rest of
the shafts. The pH, electrical conductivity and temperature at Shaft 1 were similar to
those in Shaft 3 (Figure 11). There were low metal concentrations in Shaft 1. The
alkalinity, Ca, Mg, Cl, Cr, Zn, and Ni concentrations in Shaft 1 were similar to those in
Shaft 3. Barium and Chromium were in Shaft 1 but not in neighboring Shafts 2, 3, and 4.
Shaft 1 could be similar to Shaft 2, 3 and 4, but there are many differences so they could
have a similar sources, but localized differences such as bacteria ecology.
The Mouth was physically different from all the shafts, while the shafts are
vertical, the North Bloomfield Tunnel at the Mouth runs horizontally. A small amount of
water constantly drains out of the North Bloomfield Tunnel when compared to the water
flowing in Humbug Creek. There was a seep that trickles into the mouth from the walls
of the opening of the mouth. The seep was not tested.
The water chemistry of the Mouth was different from all the other shafts. The
mouth had the third highest, pH, electrical conductivity, and temperature (Figure 11). The
patterns of constituents in the Mouth are unlike the pattern in any of the shafts. The
Mouth had the third highest alkalinity which would account for its high pH. The Mouth
had the highest Fe concentration (96 mg/L) in the North Bloomfield Tunnel.
The hydrous ferrous oxide that forms on the solid surfaces of the Mouth,
Shafts 5 and 6 could be an oxidized iron species, since these sites had higher
concentrations of Fe than any of the other sites in the North Bloomfield Tunnel. None of
the other shafts had hydrous ferrous oxide or high Fe concentrations.
77
The mouth was also the third highest in Mn, Mg, and SO4 in the North
Bloomfield Tunnel. The mouth had the highest concentration of Ba, and had the second
highest concentrations of As and Ni. The difference in water chemistry at the Mouth
compared to the rest of North Bloomfield Tunnel could be because the Mouth was the
lowest point in the North Bloomfield Tunnel and was the drainage from the tunnel. If
water was flowing through the material at the bottoms of the shafts, it would be under
anoxic conditions which would favor iron reduction and iron reducing bacteria. Once the
waters reached the surface at the mouth it would be under oxidizing conditions and would
form hydrous ferrous oxides and would account for the high metal concentrations in the
mouth. If the water were flowing through the blocked part of the tunnel it would have to
flow down without any up welling otherwise the high concentrations in Shaft 5 and 6
would likely be represented in the other Shafts and the Mouth.
The high concentrations at the mouth could also be caused by particulates in
the sample. Samples were taken from the mouth on 3/9/2013 when the water in the mouth
was disturbed due to spelunkers exploring the extent of the North Bloomfield Tunnel.
This disturbance caused the water draining out of the mouth to turn turbid and red from
the hydrous ferrous oxides. When the Mouth is not disturbed the water coming out of the
mouth is relatively clear even though the bottom is covered with hydrous ferrous oxides
(Figure 34). The sample from the Mouth on 3/9/2013 could be used as an example of
typical discharge from the Mouth when it is disturbed.
Data from Gage 3 (Figure 35), which is a site on Humbug Creek below the
confluence of Humbug and Diggins Creeks, was included in Figure 35 so that the shaft
water chemistries could be compared to nearby surface waters in Humbug Creek.
78
Figure 34. Mouth of North Bloomfield tunnel undisturbed.
Samples from Gage 3 were collected by Harihar Nepal during storm events on 3/14/2012,
1/20/2012, 1/23/2012, 1/27/2012 (Appendix A, Table A-1) (Nepal, 2013). Gage 3 data
were not graphed with North Bloomfield Tunnel data for As, Cr, Cu, and Pb because
concentrations from the Gauge 3 location on Humbug Creek were so high that they
overwhelmed the North Bloomfield Tunnel data. The highest total Cu concentration in
the borings was at 5.4 µg/L while it was 92 µg/L in Gage 3 samples on 3/14/2012
(Appendix A, Table A-1). At Gage 3 SO42-, Alkalinity, Ca, Mg, Cl- and NO3- were not
measured.
Figure 35. Metals at Gage 3 and North Bloomfield tunnel.
Note: Concentrations from Gage 3 were taken from Humbug Creek during storm
events. The variable concentration in Gage 3 may be due to suspended sediment in
Humbug Creek water.
All metals graphed were measured and all columns that are not visible were below
reporting limits. Columns with values below 5 mg/L, 2 mg/L, 10 µg/L are labeled.
Reporting limits: Al <0.050 mg/L, Mn <0.010 mg/L ,Ba < 5 µg/L, Zn < 10 µg/L, Ni <1
µg/L. All values are available on in Appendix A Tables 15 and 18.
79
80
Concentrations of metals at Gage 3 were higher than those for all of the
borings except the Mouth of North Bloomfield Tunnel and Shaft 5. The difference
between the Gage 3 samples and North Bloomfield Tunnel samples could be caused by
the amount of particulate matter in the samples. Gage 3 samples were taken during storm
events. During Storm events were high flows in streams mobilizes sediment and suspends
it in the creek water. There are high concentrations of suspended sediment in Gage 3
samples while there is little suspended sediment in shaft waters, since the water is
stagnant in the shafts. Since the total metal concentration in water were tested, the
particulates could have added to the metal concentration of the samples. The Mouth,
Shaft 6, and Gage 3 have high metal concentrations that could be caused by particulates
in unfiltered water samples. The water from Shaft 5 was clear with few particulates so a
different process could be increasing metal concentration in Shaft 5 water.
Fleck et al., (2010) studied Hg at the Mouth of the North Bloomfield Tunnel
(Table 7). The Hg concentration in water at the mouth of the North Bloomfield Tunnel
was low, but in the solid material it was high (Table 7). While the mouth of the North
Bloomfield Tunnel should not be a Hg hazard if it remains undisturbed. If the mouth
were disturbed it would mobilize the sediment and Hg.
TABLE 7. SOLID SAMPLES FROM FLECK ET AL. 2007 AND WATER SAMPLES
FROM THIS STUDY
Site
Sediment
Water
size (mm)
weight (%) THg (ng/g)
THg (ng/g)
NBT Mouth
0.25-1.0
26.6
206
.063-0.25
25.1
268
<0.063
47.7
137
0.54
Note: Sediment samples are from Fleck et al. 2007. Water samples were collected as
part of this study.
81
The waters of the North Bloomfield Tunnel are complex. The complexity is
partially due to isolation of the shafts after the collapse of the North Bloomfield Tunnel.
The complex water chemistries and water levels in the shafts could indicate a fractured
ground rock aquifer with an extensive fracture network.
Hiller Tunnel
Samples from this study can be compared to samples taken from the Phase II
study conducted by the NCRCD in 1979 (Table 8). Samples in the Phase II study were
taken from below the outlet of Hiller Tunnel during a storm event on 2/13/2013
TABLE 8. HILLER TUNNEL FROM NCRCD PHASE III STUDY (2/13/1979) AND THIS STUDY
Concentrations at Hiller Tunnel
Constituent
2/13/1979
filtered
unfiltered
(mg/L)
(mg/L)
1/20/2012
unfiltered
(mg/L)
1/23/2012
unfiltered
(mg/L)
1/27/2012
unfiltered
(mg/L)
3/26/2012
unfiltered
(mg/L)
11/4/2012
unfiltered
(mg/L)
As
<0.005
0.35
<0.002
<0.002
<0.002
<0.002
<0.002
Cd
0.004
0.007
<0.001
<0.001
<0.001
<0.001
<0.001
Cr
<0.005
0.11
0.00086
0.065
0.0027
0.076
0.0059
Cu
0.01
0.7
0.0026
0.093
0.0039
0.13
<0.005
Fe
0.11
45
9.4
34
3.6
39
4.2
Mn
0.03
3
1.4
0.58
1.2
0.52
1.4
Ni
0.02
0.62
0.048
0.081
0.047
0.11
0.096
Zn
0.095
0.75
0.022
0.11
0.016
0.13
<0.05
Pb
<0.008
0.24
0
0.023
0.00074
0.02
<0.005
Ca
7.1
14
Mg
3.3
7.5
Na
2.9
4.2
K
1.4
2.7
HCO37.3
6.7
2SO4
34
69
Source: Data for table from Nevada County Resource Conservation District, 1979b, Malakoff Diggins
Water Quality Study, Phase III Progress Report: Grass Valley, California, Nevada County Resource
Conservation District, 66 p.
82
(Appendix A, Table A-1) and filtered and unfiltered samples were tested to study
dissolved metals in the water from Malakoff Diggins.
The samples from 2/13/1979 were collected during a storm event in the
middle of the rainy season (Appendix A, Table A-1). Samples taken on 1/20/2012 and
1/23/2012 were also taken during storm events (Appendix A, Table A-1). 1/27/2012 was
after the storm event on 1/23/2012 (Appendix A, Table A-1). Samples taken on
3/26/2013 were taken between days that had storm events (Appendix A, Table A-1).
Samples taken on 11/4/2012 were taken early in the rainy season when the system was
still dry.
The concentrations of trace metals in unfiltered samples tended to be highest
during storm events on 2/13/1979, 1/23/2012, and 3/26/2012 Appendix A, Table A-1)
and lowest during dry periods 11/4/2013. Trace metal concentrations were higher in
unfiltered samples in 1979 than filtered samples. During storm events, large amounts of
sediment flow through the Hiller Tunnel making the waters highly turbid. The water
coming out of Hiller Tunnel is less turbid during dry periods (DWR, 1987; Nepal, 2013).
The reason for this pattern could be that the trace metals are carried in particulates and
are not dissolved in water.
There were higher concentrations of Ca, Mg, Na, K, and SO42- in 11/4/2012
than in 2/13/1979 samples. This could be caused by many factors. Samples from
2/13/1979 were filtered while the samples from 11/4/2012 were not, so some of the ions
could have been removed during the filtering process. Calcium, Mg, Na, K, and SO42often form salts and highly soluble species. During dry periods, evaporation could cause
salts to form. During the rainy season, the salts would dissolve increasing the
83
concentrations in water. As the rainy season continues, the salts would be diluted and
removed from the area decreasing concentrations.
There are many reasons why the 2/13/1979 samples have higher
concentrations than the other Hiller Tunnel samples. The concentrations in Humbug
Creek at Gage 3 (Figure 35) fluctuate depending on discharge and turbidity. The water
years 2012 and 2013 were dry water years so there was less discharge and less turbidity
in 2012/2013 than in 1979. The concentrations from 1979 could be less accurate since
they were analyzed using older and perhaps less accurate technology. The Pit is more
eroded and vegetated reducing the amount of suspended sediment coming out of Humbug
Creek.
Borings
Infiltration of water was quick through the sediment near the borings because
of the sediment texture. The sediment texture was classified as sandy loam at P-1 and
loam at the other borings (American Society for Testing and Materials, 1985; Kathy
Berry-Garrett, pers. comm., 2013). The infiltration rate of sandy loam and loam is
expected to be 5-90 mm/hr (Meek et al., 1992). The rough estimate of infiltration was 1.5
mm/hour, slower than expected but did not take into account water flowing in from
outside of the Pit.
The infiltration may be greater than 2.57mm/hr which is supported by how
quickly the borings went from low water to full (Figure 21) and by the rapid response of
subsurface water to surface water (Figure 22). The borings were placed in an area of the
Pit that was full of willows and alder. The decomposition of plant matter and burrowing
84
animals, can leave large macropores which could allow water to flow into the subsurface
much more quickly (Ward, 1995).
The sediment in the pit near the borings was fully saturated after 4.44 inches
of precipitation while the average annual precipitation is 60 inches (NCRCD, 1979a). The
estimated specific yield for the borings was between 6.06% and 2.24% which is similar to
the specific yield found in the Escalante Valley, Utah for sandy clay loam 5.3% but it is
much lower than that found in San Diego, California for fine sandy loam 30% (Johnson,
1966). The amount of precipitation needed to saturate the pit and the low specific yield
support the conclusion that most of the water flows through the Pit adding to Malakoff
Diggins discharge problems instead of infiltrating into the ground.
More advanced models and equations such as the Green-Ampt, Horton's
Equation or Darcy's Law were not used to calculate infiltration, because the variables
(hydraulic conductivity, water content, infiltration rates) needed for the equations were
not measured and would require too many assumptions to be useful. The variables were
not measured because infiltration was outside of the scope of this study.
During the dry season surface water in the north side of the Pit flows towards
Diggins Pond, while on the south side of the Pit it flows towards Hiller Tunnel, and from
Diggins Pond the water flows back towards Hiller Tunnel (Figure 2). Once the sediment
in the Pit has become completely saturated the water becomes visible on the surface of
the Pit. During saturated conditions, sub surface water would be expected to flow in a
similar direction as the surface waters (Figure 2). Due to the vegetation in the Pit around
Hiller Tunnel, we were unable to accurately measure the elevation of the borings.
85
If the bottom of the Pit is treated as a horizontal plane then during the dry
season subsurface water would originate at boring P-2 and P-4, flow to P-1 then flow
north to P-3. This would mean water was flowing toward the center of the Pit, the
opposite direction of the observed surface water flow. There are two ways to account for
this. (1) There is an elevation change in the Pit and P-3 is at a higher elevation. (2) There
could be a pathway for the water to drain from the Pit near P-3 such as infiltration
through the collapsed material in Shaft 8 of the North Bloomfield Tunnel or through the
auriferous gravel channel that extends from the northeast to southwest of Malakoff
Diggins.
Subsurface drainage from the Pit is slow since the borings remained saturated
after the wet up period. This fits with the current model of the Pit that it is composed of
unconsolidated sediment on top of impermeable metamorphic bedrock. The bedrock acts
as a bowl retaining water in the Pit. This would account for how quickly the pit near the
borings becomes saturated because there would be little to no drainage through the
bedrock channel, so most of the groundwater would be retained from year to year with
some loss due to evaporation.
The pH of Hiller Tunnel was relatively stable between pH 5.96 and 7.3 with a
slight increase in pH during the monitoring period. The pH of the boring fluctuated from
as high as 9.19 at P-2 on 11/9/2012 to as low as 3.26 at P-1 on 12/2/2012. There are two
potential reasons for the fluctuating early season pH; (1) the borings were not fully
developed and (2) most of the rain was at the beginning of the rainy season in November
and December (Figure 8) so this could have been first flush phenomena.
86
The electrical conductivity of borings P-1, 2, and 4 at the start of this study
were high with the highest measurement on 10/12/2012 of 1.438 ms/cm2 at P- 4 before
decreasing to around 0.5 ms/cm2 on 11/4/2013 for P-1, 2, and 4 (Figure 25). The
electrical conductivity at Hiller Tunnel followed a similar pattern starting at 1.154
ms/cm2 on 10/12/2012 before stabilizing between 0.138-0.5 ms/cm2 from 11/4/2012 to
3/21/2013. The conductivity at P-3 remained high (1.656 to 0.998 ms/cm2) during the
11/4/2012 to 3/21/2013 monitoring period. The high conductivity readings on 10/12/2012
were taken during the dry season before any storms (Figure 25); therefore, evaporation
could have caused the ion concentrations to increase in the waters and to be diluted
during storm events. Boring P-3 was dry until 11/17/2012 and once it had water, it took
the boring up to 4 hours to recharge. The conductivity could have remained high due to
the low flow and the well could have been fully developed increasing the amount of
suspended sediment in samples. Since P-3 had the least water it could be the most
affected by evaporation which would increase the ion concentrations and conductivity.
There was a high clay content in the sediment which could also have caused the high
electrical conductivities.
The Hiller Tunnel tended to have lower concentrations of constituents, Fe, Ca,
Mg, Cu, Pb, Cr, Zn and Ba than the borings. The exceptions were Ni (96 µg/L) which
was higher in Hiller Tunnel than any of the borings and SO42- (69 mg/L) in Hiller Tunnel
which was higher than all of the borings except P-3 (380 mg/L). The high concentrations
of Ni and SO42- could mean that the main source for that water in Hiller Tunnel are from
areas that were not sampled and that there is little mixing between surface and subsurface
groundwater.
87
A potential source for waters that could account for the high Ni concentrations
at Hiller Tunnel are springs in the slump area (Figure 36). The springs were sampled by
Dr. Carrie Monohan on 11/4/2012. The springs have different aesthetics and were labeled
by the color of the spring. The Red Spring had hydrous ferrous oxide and the Green
Figure 36. Metals and sulfate in surface water in the pit of Malakoff Diggins.
Note: At the Green Bubble Spring Cu and Fe were below reporting limits. Samples
from Diggins Pond, Green Bubble Spring and Red Spring were gathered by Carrie
Monohan. Columns with values below 5 are labeled. Columns that do not appear on this
graph and are not labeled were below reporting limits. Reporting Limits – Cu > 0.50
µg/L, Fe >0.050 mg/L.
Spring is covered with green algae. The springs have lower pH (pH 3.88 Red Spring and
2.4 Green Spring) than the mine features analyzed in this study (Carrie Monohan, pers.
comm., 2013). There were high Ni concentrations at the springs (Figure 36) and they
could be a source of the Ni in Hiller Tunnel.
88
P-4 tended to have lower concentrations of all metals than the other borings
(Figures 26-29). P-1, 2, and 3 tend to have similar concentrations with the pattern of P-1
having the highest concentrations, then P-3, followed by P-2 for Cu, Pb, Cr, Ni, Zn, Ba,
Be, Mn, Al and K (Figure 26). P-2 has high concentrations of As (31 µg/L) when
compared to the other borings (Figure 26). P-3 had high concentrations in Fe, Mg, SO4,
Al, and Na when compared to the other borings (Figures 27 and 28). The concentrations
of metals in the borings are complex. The borings may be related but, there are many
factors that differentiate them.
Diggins Pond had much lower concentrations of metals than the borings or
Hiller Tunnel except for Al (1.8 mg/L). The metal concentrations could be lower in
Diggins Pond than Hiller Tunnel because the water in Diggins Pond moves slowly
through the pond which allows the particulates to settle out of solution while the water in
Hiller Tunnel is constantly flowing. The willows in the Pit near Diggins Pond are known
to bioaccumulate heavy metals, including Cd, that could lead to lower concentrations in
Diggins Pond (Robinson et al., 2000).
When examining the change in concentrations over time for Al, Fe, As, Cr,
Cu, Pb, Ni, and Zn for the borings P-1 and P-2 follow the same pattern of increasing late
in the season then decreasing in concentration as the season progresses (Figure 29A, B).
The concentrations for P-3 constantly increased through the sampling period (Figure
29C). P-4 increased early in the season then slowly decreased through the sampling
period (Figure 29D). This would indicate that there are three groups of subsurface waters
that correspond to the three patterns of metal concentration change over the monitoring
period.
89
Hiller Tunnel had lower total Hg concentrations (56.7 ng/L on 2/13/2013)
than the borings. The highest concentration of total Hg in the borings was 574 ng/L at P-3
on 3/22/2013 and the lowest was 189 ng/L at P-4 on 3/22/2013. The samples from the
borings were very turbid (Figure 37). The turbidity could have been caused by the
Figure 37. Bailer drawn from boring P-1 on
10/12/2012.
Note: The water in the bailer is turbid due to the
large amount of sediment suspended in solution.
90
disturbance caused by drawing water from the boring and by not screening the borings
well enough to remove clay. Hg absorbs on to solid particles giving the borings elevated
Hg concentrations (Reimers & Krenkel, 1974; Tiffreau et al., 1995; Fleck et al., 2010).
P-3 tended to have higher concentrations of metal and electrical conductivity
than the rest of the borings, Hiller Tunnel, and Diggins Pond. P-1 and P-2 are similar in
many respects so the waters may be hydraulically connected. P-4 tended to have lower
concentrations and had different seasonal patterns than the rest of the borings. A reason
for this could be that there are three different water paths; (1) one for P-3, (2) one for P-1
and 2, and (3) one for P-4 with different factors affecting each path. These three paths are
supported by the movement of water on the surface of the Pit. More borings would need
to be made to make any conclusions about the subsurface hydrology.
Statistical Analysis
From the biplot created through PCA (Figure 32) most of the samples at
Malakoff Diggins tend to fall in the same cluster for samples at Malakoff Diggins or for
the constituents Al, Fe, As, Cr, Cu, Pb, Ni, and Zn, but the borings are outliers. P-2 is an
outlier because of high As concentrations and P-1, 2, and 4 with other metals, Cr, Pb, Cu,
Zn, Al and Ni. The high metal concentrations in the borings could be from all the
particulates in the boring samples. When more concentrations, Be, Ba, Cd, Mg, Ca,
SO42-, Alkalinity (Figure 33) are taken into consideration Shaft 5 and 6 and Hiller Tunnel
are also outliers, which could correspond to the high concentrations of Ni at Hiller
Tunnel and the high metal concentrations at Shaft 5 and 6 when compared to other
features in the North Bloomfield Tunnel.
91
The correlation matrix (Figures 4 and 5) confirmed most of the relationships
found using PCA. In the correlation matrix, Al/Cr, Be/Cr, Be/Cu, Be/Pb all had
statistically significant direct relationships greater than or equal to 0.95. The one
relationship that was found using the correlation matrix that was not found using PCA
was that Ca and alkalinity have a correlation coefficient of 0.97 while they were shown
having almost an inverse relationship in PCA.
When ANOVA was performed on the dataset (Figure 3) the mean
concentrations of metals and ions were not equal and the variance of the concentrations
were not equal. When samples were compared to one another it was found that the means
and variances of the samples were also not equal. Since the variance and mean were not
equal the dataset was variable (Table 3). The correlation matrix also showed a variable
data set with few correlations (Tables 4 and 5).
The waters of Malakoff Diggins are varied and the relationships are complex.
Because of the varied chemistries in the shafts of the North Bloomfield Tunnel, there is a
little connection between the shafts so each one should be treated separately. The borings
were also variable and there are at least three separate groundwater sources. More borings
should be installed and sampled to draw conclusions about the hydrology of the Pit.
Blue Lead
The blue lead or blue gravel was removed from 5000 ft (1.5 km) long, 500600 ft (150-180 m) wide area in the Pit near Hiller Tunnel during mining operations
(Lindgren and Walcott, 1900). If the blue lead is having an effect on the waters of
Malakoff Diggins it would have to seep in from areas that were not mined. The borings
92
are in an area where the blue lead was removed. If water was seeping into the Pit from
areas where the blue lead still exists it could account for the high concentrations of Ni in
Hiller Tunnel in relation to other Pit waters because Hiller Tunnel drains the entire Pit.
Dissolved Oxygen
Results for dissolved oxygen were not included in the study but are in the
(Appendix A, Tables A-4 and A-5), because the readings often would not stabilize.
Dissolved oxygen can be used as a measure of oxidation-reduction conditions. When the
dissolved oxygen is high and there is gas exchange with the atmosphere the conditions
are oxidizing (Eby, 2004). When dissolved oxygen is low and there is little gas exchange
with the atmosphere then conditions will tend to be reducing this process can be
catalyzed by bacteria (Eby, 2004). Most metals form soluble species under reducing
conditions and insoluble ones under oxidizing conditions (Eby, 2004).
Shafts 5 and 6 and the borings had low dissolved oxygen measurements
(Appendix A, Tables A-4 and A-5). Shaft 5 and 6 had highly turbid waters with red and
green colors, which are often a sign of eutrophication which would account for the low
dissolved oxygen (Eby, 2004).
The water in the borings is separated from the atmosphere so there were
presumably no sources of oxygen in the subsurface water, which would account for the
low dissolved oxygen (Eby, 2004). When the borings were made during the end of the
dry season we did not reach the reduced layer until a depth of 2.5-5 ft (Figure 38). The
reduced layer was where the sediment turned from tan/orange to grey which was also the
depth at which we encountered water. During the rainy season the Pit was marshy and the
93
Figure 38. Oxidation-reduction conditions in soils in the pit.
Note: Left – Footstep in Malakoff Diggins Pit sediment 3/1/2013. The red material
was bacterial and hydrous ferrous oxides. The black color in the foot step was
decomposed and reduced organic material. Right – Malakoff Diggins Pit Sediment
removed from borings. The first few feet bored from the boring was the tan oxidized
sediment. The grey black sediment was the reduced material that was below the tan
sediment.
oxidation-reduction conditions behaved like those in a marsh with conditions turning
reducing only a few mm deep (Figure 38) (Howe et al., 1981).
Limitations
The main limitations of this study was that samples were not taken at regular
intervals and conditions were not the same between sampling periods; for example,
some of the shaft samples were taken on 3/26/2012 while others were taken on
11/9/2012. The conditions at Malakoff Diggins on these two dates were very different
3/26/2012 was at the end of the rainy season in the middle of a storm event (Appendix
A, Table A-1) while 11/9/2012 was at the beginning of the rainy season and there had
been little precipitation. Similarly, Shafts 2 and 4 were not found until later in the study
94
and that was why they were not tested on 3/26/2013 and why sampling times are not
standardized.
Why Piper and Stiff Diagrams
Were Not Used
Piper and Stiff Diagrams are commonly used to analyze relationships between
waters and their water quality. The limitation of Piper diagrams are that they are series of
trilinear plots that look at Ca, Mg, Na, K, Cl, SO42-, and Alkalinity. Stiff diagrams create
polygons based on Na, Cl, Ca, Mg, HCO3-, and SO42-. These are the most commonly
found constituents in natural waters.
Piper and Stiff Diagrams were constructed for this study but yielded
inconclusive results. The Piper Diagram of the samples did not form well-defined groups.
Relationships between samples using Stiff Polygons could be found on the graphs already
made for this study. Also not all of the elements used in Piper and Stiff diagrams were
measured for each sample.
Principle component analysis was used instead of Piper or Stiff Diagrams
because it allowed for the grouping of samples based on any constituent not just ones that
were commonly found in natural waters. It also allowed for the comparison of multiple
constituents.
CHAPTER V
CONCLUSIONS
Malakoff Diggins is a source of pollution, sediment and metals, to the South
Yuba River (NCRCD 1979a, 1979b; Peterson 1976; Yuan 1979; CRWQCB-CVR 2004;
Fleck et al. 2007). Subsurface waters were studied in order to determine point sources of
contamination. Three areas at Malakoff Diggins that were studied include, (1) North
Bloomfield Tunnel, (2) Hiller Tunnel, and (3) subsurface waters in the Pit within 300 ft
of the entrance to Hiller Tunnel. The physical characteristics, hydrology and
concentrations of metals and ions were measured in each feature.
The North Bloomfield Tunnel poses a direct physical threat to park visitors
because many of the shaft openings are only partially enclosed by fences and have
sections that are damaged. The Mouth of North Bloomfield Tunnel is open and it is
possible for anyone to enter, though it is difficult to find from Humbug Creek Trail.
The North Bloomfield Tunnel has varying water levels (Table 1), conditions
(Figure 11) and concentrations of metals (Figures 12 and 13) and ions (Figure 14). From
physical measurements the North Bloomfield Tunnel is dilapidated and has partially
collapsed (Figure 11). The collapse of the North Bloomfield Tunnel may have isolated
the shafts creating the different water chemistries. The source of pollution from the North
Bloomfield Tunnel is Shaft 5 that has the highest concentration of metals (Figures 12 and
13)
95
96
and is the only shaft with a continuous and visible discharge to Humbug Creek. The
Mouth also discharges high metal concentrations into Humbug Creek.
Hiller Tunnel is the only observable point for surface water to discharge from
the Pit; therefore, it acts as a point source for all pollution from the Pit. Diggins Pond is
the largest body of surface water in the Pit that is perennial. The borings placed in the Pit
near Hiller Tunnel were used to study the subsurface waters in the Pit. Due to the
proximity of Hiller Tunnel to the borings and Diggins Pond the waters were expected to
show a relationship, but the metal and ion concentrations at Diggins Pond were much
lower than those in Hiller Tunnel.
The infiltration of water into the sediment, the wet up period (Figure 21) was
slower than expected for sandy loam and the specific yield was low but within known
range for sandy loam but this could be due to the assumptions made when estimating
infiltration rates. The surface water and subsurface water height in the borings follow one
another with little to no lag time once the borings were saturated. The sediment was in a
channel in impermeable bedrock that acts as a bowl that had little subsurface water
drainage. Both factors could contribute to the short lag time between surface and
subsurface water height.
Sites in the Pit in order of decreasing metal concentration are; borings, Hiller
Tunnel and Diggins Pond (Figures 26-28). There were a few exceptions such as Ni,
which was highest in Hiller Tunnel (Figure 26), and Al, which was high in Diggins Pond
(Figure 27). The differences in water chemistry could occur because there is little mixing
between the surface waters and subsurface waters. The high turbidity and particulates in
97
samples taken from the borings could have increased metal concentrations in the total
metal concentrations.
The water conditions and metal concentrations of the borings varied (Figures
23-28) and formed three groups showing some connectivity between subsurface waters.
Surface waters also flow along three pathways which correlate to the groups the borings
formed by water chemistry. Since there were four sites and only two sites showed a
relationship more analyses are needed to make conclusions. One way to accomplish this
would be to add more borings into the Pit.
Though samples were analyzed for total metals, which includes dissolved and
particulate portions there seems to be a pattern in metal concentration based on how
much suspended solid was in a sample, samples that had high turbidity and concentration
of particulates tended to have higher metal concentrations, than those that had lower
turbidity. Total suspended and total dissolved solids were not studied, but Nepal found
that Hg concentration increased with total suspended solids at Malakoff Diggins (Nepal,
2013). The relationship found by Nepal between Hg and total suspended solids could
extend to other metals. The relationship between suspended solids and metal
concentration would be valuable for informing future remediation efforts.
The water quality of mine features at Malkoff Diggins was poor due to the
metal concentrations. The high variability of water quality constituents in the dataset at
Malakoff Diggins indicates that there is isolation of the mine features of the North
Bloomfield Tunnel and a complex water flow regime in the Pit.
CHAPTER VI
RECOMMENDATIONS
There are many ways future research can build on and improve the data set
gathered in this study. More work can be done to study the relationship between
suspended sediment and metal concentration, because suspended sediment may be the
main factor creating the high metal concentrations at Malakoff Diggins. This can be done
by measuring metal concentrations in sediment samples, measuring dissolved and total
solid or turbidity of water samples.
In the North Bloomfield Tunnel air shaft water samples should be taken at the
water surface and at depth to see if oxidizing or reducing conditions are affecting metal
concentrations. Water samples should also be taken from the New York claim above
Shaft 5 and 6 to see if there is a relationship between water at the New York claim and
Shaft 5 and 6. A parshall flume can be placed at the Mouth and Shaft 5 of the North
Bloomfield Tunnel to measure the water and metal discharge from these mine features.
More samples could be taken from surface waters around the Pit, especially in
the pond, because the water at Hiller Tunnel has different metal concentrations from the
borings and Diggins Pond. More borings can be placed in the Pit to enlarge the study area
because to find the sources of the varying water chemistries in the borings. Samples can
be taken of precipitation to see if atmospheric deposition is contributing to the metal
concentrations in waters at Malakoff Diggins.
98
99
Infiltration studies can be conducted finding all the variables needed to use
infiltration equations, such as Green Ampt, Horton's Equation and Darcy's law, to make a
much more accurate assessment of infiltration and storage in the Pit.
Future remediation efforts should focus on removing suspended sediment
from water discharged from Malakoff Diggins. There is evidence that the high metal
concentrations in the Pit have a direct relationship to the concentration of suspended
sediment. The suspended sediment can be removed from the water by filtration. There is
limited water storage in the Pit so rerouting water around the Pit would slow erosion of
the Pit (NCRCD, 1979b).
Slowing water in the pit would have a limited effect on decreasing suspended
sediment, since the suspended sediment coming out of the pit is mainly composed of silts
and clays (DWR, 1987). The silts and clays remain suspended for a long period; after a
water sample was allowed to settle for 1 hour, 1.1 ml/L had settled out while 1,680 mg/L
remained suspended (DWR, 1987). Strategies for slowing down water such as,
impoundments and vegetation, would remove some of the sediment but much of the
sediment would continue to discharge downstream.
Remediation efforts for the North Bloomfield Tunnel should be focused on
Shaft 5 and the Mouth of the North Bloomfield Tunnel. Shaft 5 discharges so capping it
may force water to be released from another area through fractured ground rock aquifer
(Hamlin and Alpers 1996) or it could flush the debris out of the North Bloomfield
Tunnel. It may be possible to isolate Shaft 5 by placing a small berm around it. The
conditions in Shaft 5 could be changed to have more of the metals precipitate out of water
before it is discharged from the shaft. Precipitating the metals out of the waters can be
100
accomplished by increasing the pH making conditions more basic or by oxygenating the
water at depth to make the conditions at depth oxidizing instead of reducing (Eby, 2004).
REFERENCES CITED
REFERENCES
Alpers, C.N., and Hunerlach, M.P., 2000, Mercury contamination from historic gold
mining in California: US Geological Survey Fact Sheet FS-061-00, p. 6
Alpers, C.N., Hunerlach, M.P.,Gallanthine, S.K., Taylor, H.E., Rye, R.O., Kester, C.L.,
Marvin-DiPasquale, M.C., Bowell, R.J. Perkins, and W.T., Humphreys, R.D.,
2002, Environmental legacy of the California gold rush: 2. Acid mine
drainage from abandoned placer-gold mines, in Proceedings, The Geological
Society of America Annual Meeting, Denver, October 2002.
American Society for Testing and Materials, 1985, Standard test method for particle-size
analysis of soils, D 422-63, 1972, in Annual Book of ASTM Standards 04.08:
American Society for Testing Material, Philadelphia, p. 117-127.
Bear, J., Tsang, C.F., and deMarsily, G., 1993, Flow and contaminant transport in
fractured rock: San Diego, California, Academic Press, p. 548.
Bouslog, D.H., Mudslide occurrences in the tertiary gravels of the hydraulic mining pit at
Malakoff Diggins, 1977, in Harding, J., ed., Ecological studies at Malakoff
Diggins State Park, a compilation of student papers: Davis, California,
Department of Environmental Horticulture, University of California, Davis.
Brooks Rand Labs, 2013, Field sampling protocol suggestions: Seattle, Washington,
Brooks Rand Labs, 3 p.
Brady, K.S, Bigham, J.M., Jaynes, W.F., and Logan, T.J., 1986, Influence of sulfate on
Fe-oxide formation comparisons with a stream receiving acid mine drainage:
Clays and Clay Minerals, v. 34, no. 3, p. 266-274.
Byers, F.M., Carr, W.J., Orkild, P.P., Quinlivan, W.D., and Sargent, K.A., 1976,
Volcanic suites and related cauldrons of timber mountains-Oasis Valley
caldera complex, Southern Nevada: US Geological Survey Professional Paper
919, 403 p.
California Regional Water Quality Control Board-Central Valley Region (CRWQCBCVR), 2004, Executive officer’s report: California Regional Water Quality
Control Board-Central Valley Region, 45 p.
102
103
Clark, W.B., 1970, Gold districts of California: Sacramento, California, California
Divisions of Mines and Geology Bulletin 193, 186 p.
Clesceri, L.S., Greenberg, A.E., and Eaton, A.D., 1999, Standard methods for the
examination of water and wastewater (20th edition): Washington, D.C.,
American Public Health Association, 1,325 p.
Church, S.E., Mast, M.A., Martin, E.P., and Rich, C.L., Mine inventory and compilation
of mine-adit chemistry data, in Church, S.E., von Guerard, P., and Finger,
S.E., 2007, eds., Integrated investigations of environmental effects of
historical mining in the Animas River watershed, San Juan County, Colorado:
Reston, Virginia, United States Geological Survey Professional Paper 1651,
Volume I, Chapter E5, p. 255-311.
Colorado Department of Public Health and Environment, 2003, Total maximum daily
load for mercury in McPhee and Narraguinnep reservoirs, Colorado, Phase I:
Denver, Colorado, Colorado Department of Public Health and Environment,
Water Quality Control Division, 67 p.
Department of Water Resources, 1987, Erosion control at Malakoff Diggins State
Historic Park, Report to the Department of Parks and Recreation interagency
agreement 05-07-075 (DWR 163543), Central district, January 1987:
Sacramento, California, Department of Water Resources.
Eby, G.N., 2004, Principles of environmental geochemistry (first edition): Pacific Grove,
California, Brooks/Cole, 514p.
Fleck, J.A., Alpers, C.N., Marvin-DiPasquale, M., Hothem, R.L., Wright, S.A., Ellet, K,
Beaulieu, E., Agee, J.L., Kakouros, E., Kieu, L.H., Eberl, D.D., Blum, A.E.,
and May, J.T., 2010, The effects of sediment and mercury mobilization in the
South Yuba River and Humbug Creek confluence area, Nevada County,
California, Concentrations, Speciation, and Environmental Fate—Part 1, Field
Characterization: U.S. Geological Survey Open-File Report 2010-3125A, 120
p.
Hamlin, S.N., and Alpers, C.N., 1996, Hydrogeology and geochemistry of acid mine
drainage in ground water in the vicinity of Penn mine and Camanche
Reservoir, Calaveras County, California, Second-Year Summary, 1992-93:
U.S. Geological Survey Water-Resources Investigations Report 96-4257, 52
p.
Hoffman, C.F., 1872, Map showing the property of the Bloomfield Hydraulic Mining
Company, Nevada County, CA: Hoffman and Graven, scale 2.5 in:1,000 ft., 1
sheet. [Bancroft Library Collection]
104
Howe, B.L., Howarth, R.W., Teal, J.M., and Valteta, I., 1981, Oxidation-reduction
potentials in salt marsh: Spatial patterns and interactions with primary
production: Limnology and Oceanography, v. 26, no. 2, p. 350-360.
Jackson W.T., 1967, Report on The Malakoff Mine, the North Bloomfield Mining
District, and the town of North Bloomfield: Sacramento, California, Division
of Beaches and Parks, Department of Parks and Recreation, State of
California.
Johnson, A.I., 1966, Specific yield – Compilation of specific yields for various minerals:
U.S. Geological Survey Open-File Report 63-59, 119 p.
Kacaroglu, F., 1999, Review of groundwater pollution and protection in karst areas:
Water, air, and soil pollution: Water, Air, and Soil Pollution, v. 113, no. 1-4,
p. 337-356.
Lindgren, W., 1911, The tertiary gravels of the Sierra Nevada of California: U.S.
Geological Survey Professional Paper 73.
Lindgren, W., and Walcott, C.D., 1900, Geologic atlas of the United States, Colfax folio
California: U.S. Geological Survey, scale 1:125 000, 4 sheet, 12 p. text.
Marvin-DiPasquale, M., Agee, J.L., Kakouros, E., Kieu, L.H., Fleck, J.A., and Alpers,
C.N., 2010, The effects of sediment and mercury mobilization in the South
Yuba River and Humbug Creek confluence area, Nevada County, California,
Concentrations, speciation, and environmental fate—Part 2, Laboratory
Experiments: U.S. Geological Survey Open-File Report 2010-1325B, 66 p.
Meek, B.D., Rechel, E.R., Carter, L.M., DeTar, W.R., Urie, A.L., 1992, Infiltration rate
of as sandy loam soil: Effects of traffic tillage, and plant roots: Soil Science
Society of America Journal, v. 56, no. 3, p. 908-913.
National Weather Service, 2013, National Weather Service, California Nevada river
forecast center, climate station precipitation summary:
http://www.cnrfc.noaa.gov/awipsProducts/RNOWRKCLI.php (accessed June
2013).
Nepal, H., 2013, Sediment and mercury loads and sources at Humbug Creek from
Malakoff Diggins [M.S. thesis]: Chico, California State University, p. 107.
Nevada County Resource Conservation District, 1978, Malakoff Diggins water quality
study: Phase I report: Grass Valley, California, Nevada County Resource
Conservation District, 49 p.
105
Nevada County Resource Conservation District, 1979a, Malakoff Diggins water quality
study, Phase II progress report: Grass Valley, California, Nevada County
Resource Conservation District, 79 p.
Nevada County Resource Conservation District, 1979b, Malakoff Diggins Water Quality
Study, Phase III Progress Report: Grass Valley, California, Nevada County
Resource Conservation District, 66 p.
Newton, G., Reynolds, S., Newton-Reed, S., Tuffly, M., Miller, E., Reeves, S.,
Mistchenko, J., and Bailey, J., 2000. California's abandoned mines, A report
on the magnitude and scope of the issue in the state, Volume I: Sacramento,
California: Department of Conservation, Office of Mine Reclamation,
Abandoned Mine Lands Unit.
North Bloomfield Gravel Mining Company, 1872a, Plan of Bloomfield Tunnel and
gravel mines owned by North Bloomfield Gravel Mining Company, Nevada
County, Cal: San Francisco, California [?], North Bloomfield Gravel Mining
Company, scale 1:24 000, 1 sheet. [Bancroft Library Collection and California
Society of Pioneers]
North Bloomfield Gravel Mining Company, 1872b, Plan of North Bloomfield Gravel
Mining Company and several locations for a bedrock tunnel bottom deep
gravel, Spring Valley Water Company, 1872, scale 1:9600. [Bancroft Library
Collection].
North Bloomfield Gravel Mining Company, 1876, Annual Report to the shareholders of
the North Bloomfield Gravel Mining Company with statement of accounts:
San Francisco, North Bloomfield Gravel Mining Company. [Bancroft Library
Collection].
North Bloomfield Gravel Mining Company, 1877, Annual report to the shareholders of
the North Bloomfield Gravel Mining Company with statement of accounts:
San Francisco, North Bloomfield Gravel Mining Company. [Bancroft Library
Collection].
North Bloomfield Gravel Mining Company, 1898a, Patterson mining collection, Box#
001400, North Bloomfield Gravel Mining Company books of various papers,
water records 1898: San Francisco, California, California Society of Pioneers.
North Bloomfield Gravel Mining Company, 1898b, Patterson mining collection, Box#
001400, July 1, 1898: San Francisco, California, California Society of
Pioneers.
106
Peterson, D.H., 1976, A study of modern sedimentation at Malakoff Diggins State
Historic Park, Nevada County, California [MS thesis]: University of
California, Davis, 86 p.
Reimers, R.S, and Krenkel, P.A., 1974, Kinetics of mercury absorption and desorption in
Sediments: Journal Water Pollution Control Federation, v. 46, n. 2, p. 352365.
Robinson, B.H., Mills, T.M., Petit, D., Fung, L.E., Green, S.R., and Clothier, B.E., 2000,
Natural and induced cadmium-accumulation in poplar and willow:
Implications for phytoremediation: Plant and Soil, v. 227, p. 301-306.
Saucedo, G.J., Wagner, D.L., and Martin, R., 1992, Geologic map of the Chico
quadrangle, California: California Department of Conservation – Department
of Mines and Geology, scale 1:250,000, 1 sheet.
Sawyer, Judge Lorenzo, 1884, Final Decree: Edwards Woodruff vs. North Bloomfield
Gravel Mining Company, U.S. Circuit Court of the Northern District of
California, Case No. 2900: San Francisco, California, National Archives at
San Francisco, 225 p.
Smith H., 1871, Plan of gravel claims owned by the North Bloomfield Gravel Mining
Company: San Francisco, California, Edward Bosqui & Co. Printers.
Stanton, M.R., Fey, D.L., Church, S.E., Holmes, C.W., Processes affecting the
geochemical composition of wetland sediment, in Church, S.E., von Guerard,
P., and Finger, S.E., 2007a, eds., Integrated investigations of environmental
effects of historical mining in the Animas River watershed, San Juan County,
Colorado: Reston, Virginia, United States Geological Survey Professional
Paper 1651, Volume II, Chapter E25, p. 1029-1065.
Stanton, M.R., Yager, D.B., Fey, D.L., Wright, W.G., Formation and geochemical
significance of iron bog deposits, in Church, S.E., von Guerard, P., and
Finger, S.E., 2007b, eds., Integrated investigations of environmental effects of
historical mining in the Animas River watershed, San Juan County, Colorado:
Reston, Virginia, United States Geological Survey Professional Paper 1651,
Volume II, Chapter E14, p. 689-721.
The Sierra Fund, 2013, Humbug Creek watershed, draft watershed assessment: Nevada
City, California.
Thomas, T., and Scott, E., 2013, Third 2013 snow survey shows continuing dry
conditions: Sacramento, California, Department of Water Resources.
107
Tiffreau, C., Lützenkirchen, and J, Behra, P., 1995, Modeling the adsorption of mercury
(II) on (Hydr)oxides, I. Amorphous iron oxide and α-quartz: Journal of
Colloid and Interface Science, v. 172, no. 1, p. 82-93.
Uren E.C., 1932, The Bloomfield Gravel Company, North Bloomfield CA: Berkeley,
California, Bancroft Library, scale 1in:1,000ft.
US Forest Service, Bureau of Land Management, 2007, Abandoned mine lands: A
decade of progress reclaiming hard rock mines: US Forest Service FS-891,
Bureau of Land Management BLM-WO-GI-07-013-3720, 40 p.
US Geological Survey, 2012, North Bloomfield quadrangle, California-Nevada County,
7.5-Minute Series: US Geological Survey, scale 1:24 000, 1 sheet.
US Geological Survey, 2013, National Elevation Dataset 1/3 arc-second, Western United
States: US Geological Survey: http://viewer.nationalmap.gov/viewer/
(accessed August 2013).
Ward, A.D., and Elliot, W.J., 1995, Environmental hydrology: Boca Raton, Florida, CRC
Press, p. 462.
Wakabayashi, J., and Sawyer, T.L., 2001, Stream incision, tectonics, uplift, and evolution
of topography of the Sierra Nevada, California: Journal of Geology, v. 109, p.
539-562.
Weather Underground, 2013, History for KCANEVAD14:
http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KC
ANEVAD14&graphspan=custom&month=1&day=1&year=2012&monthend
=6&dayend=16&yearend=2012 (accessed May 2013).
Whitney, J.D., 1880, The auriferous gravels of the Sierra Nevada of California,
Contributions to American Geology Volume I: Cambridge, Massachusetts,
Harvard University Press, John Wilson & Sons, 664 p.
Yuan G., 1979, The geomorphic development of an hydraulic mining site in Nevada
County, California [MS Thesis]: Stanford University, 54 p.
APPENDIX A
109
110
TABLE A-2. LOCATION OF HILLER TUNNEL AND BORINGS
Site
Location
Error
Lat.
Long.
(°N)
(°W)
P-1
39° 22.160’ N
120° 55.307’ W
± 9ft
P-2
39° 22.153’ N
120° 55.340’ W
± 9ft
P-3
39° 22.194’ N
120° 55.316’ W
± 9ft
P-4
39° 22.156’ N
120° 55.307’ W
± 9ft
Hiller Tunnel Inlet
39° 22.145' N
120° 55.302' W
± 10 ft
Hiller Tunnel Outlet
39° 22.048' N
120° 55.259’ W
± 11 ft
TABLE A-3. TOTAL HG AT MALAKOFF DIGGINS
Total Hg
Hg
Site
Date
(ng/L)
filtered(ng/L)
Mouth
0.49
0.21
3/9/2012
Mouth
0.54
0.31
2/13/2012
Shaft 1
4.36
2.41
3/26/2012
Shaft 2
2.02
0
11/9/2012
Shaft 3
16.7
1.07
3/26/2012
Shaft 4
2.96
0
11/9/2012
Shaft 5
2270
0.51
3/26/2012
Shaft 6
25.5
0.22
3/26/2012
Hiller Tunnel
56.7
2.49
2/13/2013
Diggins Pond
12
1.07
3/26/2012
P-1
295
0.15
3/22/2013
P-2
189
0.16
3/22/2013
P-3
574
1.26
3/22/2013
P-4
337
0.44
3/22/2013
111
TABLE A-4. IN SITU MEASUREMENTS FOR SURFACE WATERS AT MALAKOFF DIGGINS
Site
Constituent
Date
3/26/2012
Lake
City
NBT
Mouth
Shaft 1
Shaft 2
Shaft 3
Shaft 4
Shaft 5
5/5/2012
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
9
0.413
83.1
9.59
8.02
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
11.12
0.937
88.6
9.7
7.84
10.67
0.22
61
3.41
7.43
5.66
0.193
100
15.61
6.67
10/12/2012
11/9/2012
11/20/2012
11.16
0.465
102.2
11.04
6.89
8.82
0.431
8.28
7.06
0.202
90
6.56
8.97
0.32
8
11.19
1.149
26.8
2.96
6
11.48
1.164
6.8
0.72
6.26
11.37
0.538
21.6
2.28
5.68
12/2/2012
112
Table A-4 (Continued)
Site
Shaft 6
Hiller
Tunnel
(Entrance)
Hiller
Tunnel
(Exit)
Diggins
Pond
Constituent
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
Date
3/26/2012
5/5/2012
7.97
1.087
41.2
4.85
5.92
10.03
1.323
6.6
0.66
6.68
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
10/12/2012
10.58
1.154
24.4
2.47
6.42
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
8.1
0.042
71.3
8.66
5.87
12.59
0.042
35.9
3.82
6.76
14.1
0.055
41.1
3.72
6.79
11/9/2012
11/20/2012
12/2/2012
9
0.194
91.6
10.43
6.42
9.65
0.041
91.1
10.3
6.38
8.84
0.196
104
11.94
6.57
9.12
0.041
98
11.3
5.96
113
Site
Constituent
Date
12/14/2012
Lake
City
NBT
Mouth
Shaft 1
Shaft 2
Shaft 3
Shaft 4
1/11/2013
2/9/2013
3/1/2013
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
10.62
0.35
84.4
9.36
7.34
3/9/2013
3/10/2013
114
Site
Constituent
Date
12/14/2012
Shaft 5
Shaft 6
Hiller
Tunnel
(Entra
nce)
Hiller
Tunnel
(Exit)
Diggin
s Pond
T (°C)
EC
(ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC
(ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC
(ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC
(ms/cm^2)
DO (%)
DO (mg/L)
pH
T (°C)
EC
(ms/cm^2)
DO (%)
DO (mg/L)
pH
1/11/2013
2/9/2013
3/1/2013
11.21
11.19
11.33
0.534
48.1
5.09
6.99
0.415
24.7
2.63
6.57
0.419
17.4
2.9
6.22
3/9/2013
2.5
1.34
1.212
10.07
8.25
0.142
107.5
14.65
6.17
0.154
101.2
14.22
6.87
0.117
86.02
12.18
6.84
0.161
78.9
8.89
6.84
0.149
87.5
10.62
7.29
2.54
1.4
0.142
104.1
14.17
6.57
0.138
124.2
17.02
7.3
3/10/2013
3.94
0.13
101.6
13.31
7.11
115
TABLE A-5. IN SITU MEASUREMENTS FROM BORINGS
Site
Constituent
Date
10/12/2012
P-1
P-2
P-3
P-4
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
H2O Depth (ft)
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
H2O Depth (ft)
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
H2O Depth (ft)
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
H2O Depth (ft)
12.41
1.225
34.3
3.42
6.74
8.12
11.65
0.689
18.7
2.02
6.11
5.86
11/4/2012
11/9/2012
11.58
0.492
5.72
11.67
0.321
5.4
11.58
0.49
5.72
12/2/2012
11.24
0.537
44.5
4.65
7.48
10.23
0.505
22.2
2.57
6.1
9.35
0.509
19.7
2.23
3.62
10.8
0.317
55.4
6.45
9.19
10.91
0.315
16
1.72
6.58
10.7
0.317
21.4
2.34
5.52
10.59
1.375
44.3
4.96
6.23
9.86
1.61
37.7
4.17
6.84
10.12
0.38
15.2
1.68
6.12
9.44
0.337
45.35
5.02
5.81
NO WATER IN BORING
12.73
1.483
12.7
1.3
6.04
7.01
11/20/2012
10.4
0.279
33.2
3.51
7.8
Note: There was no water in Boring P-3 till 11/20/2012 to take measurements from
116
Site
Constituent
Date
12/14/2012
P-1
P-2
P-3
P-4
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
H2O Depth (ft)
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
H2O Depth (ft)
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
H2O Depth (ft)
T (°C)
EC (ms/cm^2)
DO (%)
DO (mg/L)
pH
H2O Depth (ft)
1/11/2013
2/9/2013
3/1/2013
3/9/2013
3/21/2013
5.53
0.396
9.5
1.19
7.24
4.34
9.84
0.261
24.5
2.74
6.38
3.2
6.52
1.124
30.3
3.68
6.63
3.62
6.38
0.261
26.2
3.07
6.35
4.11
6.21
0.379
182
2.18
6.94
8.48
0.489
54
6.05
6.84
5.99
0.63
24.9
3.05
6.82
5.44
0.411
29.1
3.56
6.41
5.16
0.392
38.1
4.66
6.03
10.51
0.317
37.2
4.07
7.22
10.3
0.392
21.5
2.41
7.55
9.86
0.256
21.4
2.41
5.86
9.82
0.255
28.1
3.15
6.1
8.69
1.509
58.2
6.66
7.18
6.54
1.656
52.3
6.3
6.87
6.21
1.084
45
5.51
6.03
6.62
0.998
32.8
3.97
6.26
8.72
0.359
38.1
4.36
6.54
7.22
0.437
28.7
33.5
6.71
6.45
0.271
36.7
4.41
6.2
6.56
0.264
24.2
2.96
6.03
Note: There was no water in Boring P-3 till 11/20/2012 to take measurements from
10.1
0.255
17.8
2
6.75
6.981
1.221
43.5
5.23
7.14
7.16
0.256
16.6
1.98
6.18
117
TABLE A-6. P-1, P-2 , P-3, P-4 , AND HILLER TUNNEL 11/4/2012
Hiller
Constituent
P-1
P-2
P-3
P-4
Units
Tunnel
Alkalinity
CaCO3
140
42
460
53
6.7
mg/L
HCO3
140
42
53
6.7
mg/L
2<3.0
<3.0
mg/L
CO3
OH
<3.0
<3.0
mg/L
2SO4
20
44
25
69
mg/L
Al
14
11
18
0.86
0.14
mg/L
Sb
<2.0
<2.0
<2.0
<2.0
<2.0
µg/L
As
8.2
31
4.6
3.9
<2.0
µg/L
Ba
0.42
0.22
0.18
0.13
0.071 mg/L
Be
1.7
1.2
1.1
<1.0
<1.0
µg/L
Cd
<1.0
<1.0
<1.0
<1.0
<1.0
µg/L
Ca
37
13
170
12
14
mg/L
Cr
60
49
53
<10
<10
µg/L
Cu
110
64
69
7.8
5.9
µg/L
Fe
72
66
32
51
4.2
mg/L
Pb
30
20
21
<5.0
<5.0
µg/L
Mg
22
7.7
98
5.5
7.5
mg/L
Mn
1.9
2.8
2.8
2
1.4
mg/L
Hg
<0.40
<0.40
<0.40
<0.40
<0.40
µg/L
Ni
88
60
78
30
96
µg/L
K
2.8
3
4.8
<2.0
2.7
mg/L
Se
<2.0
<2.0
<2.0
<2.0
<2.0
µg/L
Ag
<10
<10
<10
<10
<10
µg/L
Na
6.1
3.8
41
4.1
4.2
mg/L
Tl
<10
<10
<10
<10
<10
µg/L
Zn
130
79
94
<50
<50
µg/L
Hardness
183
64
828
53
66
mg/L
118
TABLE A-7. NORTH BLOOMFIELD TUNNEL AND DIGGINS POND
Constituent
Al
Ca
Fe
Mg
Mn
Hardness
Cl
NO3SO42Alkalinity
Sb
As
Ba
Be
Cd
Cr
Cu
Pb
Hg
Ni
Se
Ag
Tl
Zn
Mouth
0.054
49
96
11
3.4
89
100
<0.50
4.2
87
<0.50
<1.0
<0.50
0.60
<0.50
<0.40
90
<2.0
<0.25
<1.0
13
Shaft 1
Shaft 2
Shaft 3
Shaft 4
Shaft 5
Shaft 6
Diggins
Unit
0.11
13
2.4
3.4
0.43
170
1.7
<1.0
0
56
<0.50
<2.0
19
<0.50
<1.0
0.53
<0.50
<0.50
<0.40
<1.0
<2.0
<0.25
<1.0
<10
<0.050
49
0.21
8.5
0.49
160
0.47
12
0.46
1.4
<0.010
35
1.5
<1.0
3.7
33
<0.50
<2.0
<5.0
<0.50
<1.0
0.75
0.81
0.69
<0.40
<1.0
<2.0
<0.25
<1.0
<10
2.5
50
2.8
3.5
0.16
140
1.1
39
40
15
4.4
160
2.3
<1.0
150
50
<0.50
5
28
<0.50
<1.0
2.1
4.5
1.5
<0.40
180
<2.0
<0.25
<1.0
150
0.087
40
18
15
4.1
160
2.3
1.1
130
57
<0.50
<2.0
23
<0.50
<1.0
0.52
<0.50
<0.50
<0.40
15
<2.0
<0.25
<1.0
47
1.8
1.2
2
0.7
0.082
5.8
1.8
<1.0
4.6
8.9
<0.50
<2.0
23
<0.50
<1.0
2.5
1.7
<0.50
<0.40
4.3
<2.0
<0.25
<1.0
<10
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
23
160
<0.50
2.3
65
<0.50
<1.0
<0.50
<0.50
<0.50
<0.40
<1.0
<2.0
<0.25
<1.0
<10
15
120
<0.50
<2.0
<5.0
<0.50
<1.0
<0.50
5.4
6.5
<0.40
<1.0
<2.0
<0.25
<1.0
<10
119
TABLE A-8. HILLER TUNNEL AND DIGGINS POND METALS
Hiller
Hiller
Hiller
Hiller
Hiller
Diggins
Tunnel
Tunnel
Tunnel
Tunnel
Tunnel
Pond
1/20/2012 1/23/2012 1/27/2012 3/27/2012 11/4/2012 3/26/2012
Arsenic
Beryllium
Copper
Lead
Chromium
Nickel
Zinc
Barium
Iron
<2
<1
2.6
<5
0.86
48
22
64
9.4
<2
1.8
93
23
65
81
110
190
34
<2
<1
3.9
0.74
2.7
47
16
68
3.6
<2
2.4
130
20
76
110
130
230
39
Calcium
Magnesium
Sulfate
Aluminum
Manganese
Potassium
Sodium
0.13
1.4
20
0.58
0.7
1.2
22
0.52
Unit
<2
<1
5.9
<5
<1
96
<10
71
14
<2
<1
1.7
<5
2.5
4.3
<10
23
2
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
mg/L
4.2
1.2
mg/L
0.7
4.6
1.8
0.082
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
7.5
69
0.14
1.4
2.7
4.2
120
TABLE A-9. SEASONAL CHANGES IN METAL CONCENTRATIONS
IN BORING
11/4/
12/2/ 2/9/
3/9/
3/22/
Boring Metal
unit
2012
2012 2013 2013 2013
P-1
Aluminum
14
4.4
17
37
19
mg/L
Iron
72
21
54
110
64
mg/L
Arsenic
8.2
2.1
3.5
5.4
5.6
µg/L
Lead
30
8.9
29
59
31
µg/L
Chromium
60
18
59
120
63
µg/L
Copper
110
29
98
200
100
µg/L
Nickel
88
39
93
180
100
µg/L
Zinc
130
<50
120
250
120
µg/L
P-2
Aluminum
11
13
29
12
mg/L
Iron
66
73
95
71
mg/L
Arsenic
31
29
18
21
µg/L
Lead
49
58
110
50
µg/L
Chromium
64
63
140
63
µg/L
Copper
20
19
38
18
µg/L
Nickel
60
60
110
61
µg/L
Zinc
79
81
190
87
µg/L
P-3
Aluminum
32
62
79
96
mg/L
Iron
53
98
130
160
µg/L
Arsenic
69
140
170
230
µg/L
Lead
78
150
190
250
µg/L
Chromium
94
170
240
310
µg/L
Copper
4.6
3
4.5
4.2
µg/L
Nickel
21
38
49
62
µg/L
Zinc
18
34
43
52
mg/L
P-4
Aluminum
0.86
35
27
14
mg/L
Iron
3.9
5.3
5.3
3.2
µg/L
Arsenic
<2.0
55
43
21
µg/L
Lead
<5.0
99
80
40
µg/L
Chromium
7.8
170
120
64
µg/L
Copper
30
160
120
67
µg/L
Nickel
<10
220
180
90
µg/L
Zinc
51
130
120
84
mg/L
121
Metal
As
Cr
Cu
Pb
Ni
Zn
Ba
Al
Mn
Fe
TABLE A-10. GAGE 3 METALS
Gage 3 3/14
Gage 3 1/20
Gage 3 1/23
Gage 3 1/27
<2
<2
<2
<2
56
0.53
39
0.97
92
1.3
57
1.5
21
<0.5
15
<0.5
79
23
56
14
95
50
68
<10
170
50
120
38
15
0.054
11
0.2
0.39
0.57
0.37
0.21
26
9.4
34
3.6
units
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
µg/L
mg/L
mg/L
mg/L
3
0
1
2
Variances
4
5
6
122
Comp.1
Comp.3
Comp.5
Comp.7
Figure A-1. Components for Biplot of subsurface waters at Malakoff Diggins based on
Al, Fe, As, Cr, Cu, Pb, Ni, and Zn.
123
Figure A-2. Components for Biplot of Subsurface waters at Malakoff Diggins based on
all constituents with concentrations over reporting limits.

SUBSURFACE WATERS AT MALAKOFF DIGGINS: PIT, NORTH

Transcription

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