Impact of Mine Drainage and Distribution of Heavy Metal Contamination in the James Creek Watershed Laura Harrington, Duke University Joe Ryan and Ned Turner, University of Colorado at Boulder 2002 REU Program – 7 August 2002 Department of Civil, Environmental, and Architectural Engineering University of Colorado, Boulder Laura Harrington, Duke University Joe Ryan and Ned Turner, University of Colorado at Boulder 2002 REU Program – 7 August 2002 Department of Civil, Environmental, and Architectural Engineering University of Colorado, Boulder

Outline Introduction –Acid Mine Drainage –James Creek Watershed Problem Statement Methods –Tracer Injection Experiment –Synoptic Sampling Results –Chloride Monitoring –Metal Measurements Implications

Acid Mine Drainage Sulfide-containing rocks from mines or tailings piles interact with air and water to produce sulfuric acid This results in acidic conditions in adjacent surface and groundwater sources Acidic drainage also dissolves metals from mining waste rock and leads to heavy metal contamination in the water

Mining History in Jamestown Mining –from 1850s to 1980s –ores gold, silver lead fluorospar, CaF uranium –mines Golden Age, Burlington, Argo, Emmet, Fair Day, John Day

James Creek Watershed

Lower James Creek Stretch of stream from below Little James to the confluence with Left Hand Creek Notable characteristics: –Mostly residential areas –Adjacent to town park (an old tailings pile) and Curie Springs –Affected by several inflowing gulches Elysian Park

Problem Statement Metal contamination resulting from acid mine drainage poses threats to aquatic life and human drinking water sources Further evidence of the scope of contamination is needed before remediation efforts can commence Objective of this study: –Identify contamination sources –Quantify metal loading into Lower James Creek –Suggest appropriate remediation plan

Experimental Methods Field Methods –Tracer injection –Synoptic sampling Laboratory Analysis –Ion specific electrode –Inductively Coupled Plasma – Mass Spectroscopy (ICP-MS) Calculations –Stream Discharge –Metal Loading

Tracer Injection Experiment Cost Effective Remediation –Requires determination of metal loading sources –Sources and behavior of metals are unclear without discharge measurements Determination of discharge –Flow meters are not entirely accurate –Tracer injections accurately measure the discharge of a stream

Tracer Injection Methods Tracer injected at Water Treatment Facility located just upstream from the Little James confluence Synoptic samples taken while tracer concentration is the same throughout the creek (on plateau) –Injection lasted 3 hrs 15 mins –Pump monitored during experiment to ensure constant rate –Samples collected at upstream and downstream sites to monitor the movement of the tracer

Synoptic Sampling Sites Samples taken approximately 200 m apart (at 100 m intervals around the park) along the 5 km stretch of creek Four points sampled as potential inflows ( )

Sampled Inflow Sites Curie Springs – where radioactive water was bottled for medicinal purposes as late as the 1950’s, potential source of uranium Potential ground water source flowing on opposite side of road from creek, suspected under road flow into the creek Sampled inflow located furthest downstream, potentially flow from Castle Gulch; currently dried up Inflow that flows into creek from opposite side of road, most likely flow from Buffalo Gulch

Laboratory Analysis Upstream and Downstream Sites –Samples measured for [Cl-] using ISE Synoptic Samples –pH measured and [Cl-] measured using ISE –Total metals samples prepared by acidifying with 2-3 drops of HNO 3 (trace metal grade) –Dissolved metals samples prepared by filtration through 0.2  m cellulose acetate membranes and acidifying with 2- 3 drops of HNO 3 (trace metal grade) –Metal samples analyzed on ICP-MS for Al, Cu, Fe, Pb, Mn, U, Zn

Calculations Stream Discharge: Metal Loading: –Metal loading rates = metal concentrations x stream discharge rates – Q s is the discharge of the stream – Q i is the rate of injection into the stream (1.26 L/min) – C i is the tracer concentration in the injection solution (3.0 M) – C B is the tracer concentration downstream from the injection point – C A is the tracer concentration upstream from the injection point

Results of Cl - Monitoring Purpose of upstream and downstream monitoring: Due to underestimation of travel time, trailing edge of tracer was not measured downstream –Ensured synoptic samples were taken on the plateau –Calculated tracer travel time to be m/s

Cl- Results from Synoptic Sampling Do not see expected dilution in [Cl - ] as tracer travels downstream Likewise, there is not an observed increase in stream discharge moving down the Lower James Creek

Results of Metal Analysis Observed Trends: –Spike in metal loading seen just downstream from confluence with Little James for all metals except Zn –Similar spike seen about 4.5 km downstream from injection –Decreases in loading observed after spikes could suggest metal precipitation –Sampled inflows do not always show significant metal loading

Results of Metal Analysis Observed Trends: –Around the park, Cu and Pb appear to be the only metals draining into the creek –Observed Zn jump just downstream from the park –Spike in Cu seen after Curie Springs, although no significant U contribution –Do not see significant increase in metal loading from m, except Cu

Inflow Results Increases in metal concentration downstream of inflows tend to be small, but could be attributed to the inflow sources The two downstream inflows are similar in character, with major contributions from Al, Mn, Fe, and Zn Inflow sample in area of the park differs because Fe is the only major contributor

Accumulation Total accumulation graphs emphasize amount of metal added over stretch of creek Jumps indicate where there was an inflow between sampled sites Observe jumps in similar areas for other metals Greatest relative accumulation seen for zinc

pH effect pH of samples ranged between Cannot assign causal relationship between pH variation and increases in metal loading, however correlation can be considered Decreases in pH seen just upstream for samples where where a spike in metal loading was observed

Possibility of Precipitation Pictures show progressive downstream view of stream about 4.5 km downstream from injection (where metal spike was observed) Middle picture shows distinctly lighter sediment than both the upstream and downstream sites This could be visible evidence of Al precipitation in creek just downstream from metal source

Conclusions Little James Creek and unidentified inflow about 4.5 km downstream appear to be greatest sources of metal into the creek Effects of inflowing metals is spatially controlled as a result of precipitation Elysian Park was not as significant a metal contributor as was expected prior to experimentation This does not mean that the reclaimed tailings area does not pose a threat as a metal source Our results may be limited in identifying all contributing sources due to the extremely dry conditions this summer

Further Research Current research includes conducting similar studies on the upper reach of James Creek and on the Little James Creek Future research would include testing sediments samples from the creek to look for evidence of precipitated metals

Acknowledgements National Science Foundation for funding for REU program Joe Ryan Ned Turner Mark and Colleen Williams Joy Jenkins, Sabre Duren, and Leandro Fernandez