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NRM Staff and students measuring water quality of Colorado Gulch water. 1.3 Methods The following section describes the methods associated with cell construction, substrate recipe design, flow through cells and water quality, daily collection of Colorado Gulch stream water, and weel~ly collection of water quality aliquots for laboratory analysis. The bench scale test was housed in the CMC NRM Atrium (Greenhouse) in order to provide a stable environment for the 8 week period. 1.3.1 Bioreactor Cell Construction Each cell was constructed using a HDPE plastic 30-gallon barrel, with a detachable lid. A 10-Slot polyvinylchloride (PVC) French drain, 2" outer diameter, 1 3/4" inner diameter was connected to a male coupling with a gasket, and placed through a 2" hole inside of the barrel and sealed with silica based sealant. The bottom 5-6" of each cell was filled with drii~lcing water grade #10-#20 silica sand and covered with a nylon netting. The silica sand held the French drain in place and along with the nylon netting filtered effluent water and aided in drainage. 1.3.2 Substrate Recipe Design The recipe for each substrate was compiled from information given by Jim Gusek (Golder and Associates), US BLM, and from previous testing (California Gulch). These substrate recipes were also used in a similar Bioreactor bench scale test run by Karl Ford (BLM) at the Dinero Tunnel. A list of materials, provided by Jim Gusek, included the required substrate quantities of alfalfa hay, cow manure, limestone, wood chips, sawdust, and limestone kiln dust. A Control Cell was also included that had a composition equivalent to the average substrate composition of Cells 1-4. CMC NR1VI acquired these materials from local businesses and contributors for miiumal costs. Each cell consisted of different combinations of the acquired materials in an attempt to determine the most effective metal removal recipe. The cell recipes are shown in Table 1.