Geochemical data for Upper Mineral Creek, Colorado, under existing ambient conditions and during an experimental pH modification, August 2005

Abstract

Mineral Creek, an acid mine drainage stream in southwestern Colorado, was the subject of a water-quality study that employed a paired synoptic approach. Under the paired synoptic approach, two synoptic sampling campaigns were conducted on the same study reach. The initial synoptic campaign, conducted August 22, 2005, documented stream-water quality under existing ambient conditions. A second synoptic campaign, conducted August 24, 2005, documented stream-water quality during a pH-modification experiment that elevated the pH of Mineral Creek. The experimental pH modification was designed to determine the potential reductions in dissolved constituent concentrations that would result from the implementation of an active treatment system for acid mine drainage. During both synoptic sampling campaigns, a solution containing lithium bromide was injected continuously to allow for the calculation of streamflow using the tracer-dilution method. Synoptic water-quality samples were collected from 30 stream sites and 11 inflow locations along the 2-kilometer study reach. Data from the study provide spatial profiles of pH, concentration, and streamflow under both existing and experimentallyaltered conditions. This report presents the data obtained August 21-24, 2005, as well as the methods used for sample collection and data analysis.

Evaluating Remedial Alternatives for an Acid Mine Drainage Stream: A Model Post Audit

“…Estimates of streamflow were determined from tracer dilution. 20,25 Reactive Transport Modeling. OTEQ is formed by coupling a solute transport model 26 with a chemical equilibrium submodel (MINTEQ 27 ).…”

“…First, MC1 streamflow estimates were replaced with estimates from MC2 (streamflow decreased ∼17% from August 22 to August 24). 20 Second, the upstream boundary condition was modified to consider the effects of the pH modification. MC2 values of pH and alkalinity at 576 m were therefore released from the blind and used within a series of MINTEQ runs to develop revised concentrations of TOTH, CO 3 , Fe(II), and Fe(III) at the upstream boundary.…”

“…Application of reactive transport models requires estimates of streamflow and solute concentration. An approach used in acid mine drainage streams is to combine the tracer-dilution method with synoptic sampling. ,,− The tracer-dilution method provides estimates of streamflow, and synoptic sampling provides a spatial description of instream and inflow chemistry. In this study, a paired synoptic approach is employed to assess prediction uncertainty.…”

“…Simulations of dissolved concentration appear to closely match observed concentrations at the scale presented, whereas simulations of total recoverable concentrations generally underestimate observed concentrations (Figure 3fÀh; SI Figure S1f,h). Discrepancies between simulated and observed total recoverable concentrations are attributable to the use of MC1 concentrations to specify the upstream boundary condition (total recoverable MC2 concentrations were 20À346% higher than MC1 concentrations due to source variation 20,21 ). These discrepancies are not of consequence, Despite the agreement noted above, closer examination of the dissolved concentrations reveals substantial errors in the estimation of postremediation water quality (Figure 3jÀl; SI Figure S1k,m).…”

Groundwater–Stream Connectivity Mediates Metal(loid) Geochemistry in the Hyporheic Zone of Streams Impacted by Historic Mining and Acid Rock Drainage

“…The MC-Fen is located ∼2.8 km downstream of the first trace metal(loid) source, which includes two draining abandoned mines, Koehler Tunnel and Junction Mine, and one abandoned dry mine, Longfellow Mine (Figure 1). Prior to remediation efforts in the early 2000's, flows from the Koehler Tunnel constituted nearly 50% of flow entering the head of the stream and contained elevated concentrations of copper, lead, zinc, and arsenic (Runkel and Kimball, 2002;Walton-Day et al, 2007;Runkel et al, 2009b). In 2003, a bulkhead was installed in the Koehler Tunnel, reducing surface drainage from 11.7 to <0.3 L/s (Runkel et al, 2009a).…”