Pit Lake Characterization Project, Phase I
An interdisciplinary team from Montana Tech of the University of
Montana undertook a preliminary study of several aspects of the
Berkeley Pit to gather specific information about that pit lake
system and to gather information that could be generally applied
to all pit lakes. In this work, the chemical and biological
characteristics of the water and sediments in the Berkeley Pit were
studied to provide water quality data that can be used to predict
future water quality, to evaluate the potential for natural remediation
by bacteria such as sulfate-reducers, and to determine if partial
in situ remediation would be practical prior to the pump and treat
technologies prescribed in the U.S. Environmental Protection Agency's
Record of Decision. Depth profiles data collected semi-annually
for a one year period indicated that Berkeley Pit water quality
is constant at depth, but does change seasonally near the pit lake
surface. Organic carbon was found at concentrations of 3 to
5 parts per million, but the source of the organic carbon could
not be determined with certainty. A biological survey of the
pit lake found no sulfate reducing bacteria, however several yeasts
and fungi were found. Two of the fungi could not be identified,
thus they may have been previously unknown organisms. Work
conducted for this project led to more specific research under MWTP
Activity IV Project 9,
Activity IV Project 10,
Activity IV Project 11, and
Activity IV Project 16.
Evaluation of the Water Chemistry, Precipitates, and Sedimentation
Rate of the Berkeley Pit
Lake
Principal Investigator: Dr. Bill Chatham
The objective of this portion of the study was to determine any
changes in Berkeley Pit water chemistry with depth, investigate
the major species of precipitants that create the sediment found
in the pit lake, and to determine the system’s sedimentation
rate. It was determined that Berkeley Pit water quality does
change with depth. Surface water was found to change seasonally,
while deep water quality was constant. Gypsum and schwertmannite
were found to be the predominant precipitants in the Berkeley Pit,
with K-jarosite also being present. A rough approximation
of 100 to 250 grams of iron precipitated from the system in a year
was determined. This equates to 200 to 400 tons of K-jarosite
and 2,300 to 6,200 tons of schwertmannite per year.
Determination of Total Organic Carbon in the Berkeley
Pit Lake
Water
Principal Investigator: Dr. Doug Cameron
dcameron@mtech.edu
This portion of the project attempted to determine the source of
organic carbon found in the Berkeley Pit lake. The manner,
in which organic carbon affects the Pit lake, or any lake, depends
on the type and amount of carbon present; thus prompting the research
into the organic carbon source. Once mining ceased and the
pit was allowed to fill with water, heavy equipment was left in
the Berkeley Pit. Hence fuels and lubricants in the equipment
could account for the carbon found in the pit. Samples were
collected from several depths, and analyzed for total carbon and
inorganic carbon, which allowed the determination of total organic
carbon. Quality assurance samples suggested that the elevated
sulfate concentration within the Berkeley Pit interfered with the
TOC analysis, and the actual TOC values were 1.5 to 3.5 mg C/L.
These values are similar to the TOC of surface water flowing into
the pit, suggesting that the organic carbon in the pit emanates
from natural sources, rather than fuels and lubricants.
Sulfate Reducing Bacteria Activity in the Berkeley
Pit Lake
System
Principal Investigator: Dr. Grant Mitman
gmitman@mtech.edu
The goal of this portion of the project was to survey the Berkeley
Pit for microorganisms, specifically sulfate reducing bacteria (SRB).
Water samples were collected in the fall of 1997 and the spring
of 1998. The samples were used to inoculate Petri dishes with
I mL of liquid sample, and isolation was then attempted by streaking,
dilution, and solidification/entrapment. No SRB, or SRB activity,
was detected in the cultured samples; however, a variety of fungi
and yeasts were isolated.
Surface Water Reaction Kinetics
Principal Investigator: Dr. Courtney Young
cyoung@mtech.edu
Interactions between UV-radiation (sunlight) and the mobile-toxic
constituents within surface waters of the Berkeley Pit lake were
investigated in this portion of the study. Depth profile samples
show that water quality (DO, pH, and metals content) is improved
in surface waters compared to deeper water. To investigate
the effect of UV radiation, column studies were conducted in which
deep Berkeley Pit water samples were exposed to UV radiation.
The column studies found that UV radiation did in fact play a role
in water quality in Berkeley Pit surface waters.
Activity IV, Project 8
Final
Report
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