Laserfiche WebLink
1.1 Executive Summary <br />The Colorado Mountain College Natural Resource Management program in conjunction <br />with Trout Unlimited conducted a sulfate reducing bioreactor bench test to determine the <br />best wetland receipt for the removal of toxic metals from Colorado Gulch water. The <br />results of the SRBS bench test were used to aid in the design of a larger scale SRB <br />system in Colorado Gulch. The bioreactor cells used for this bench test were constn~cted <br />on the Colorado Mountain College campus, and the ingredients used to create the tested <br />substrates were gathered from the surrounding area. This test was conducted over a six <br />week period for which influent and effluent water quality parameters (pH, Redox, <br />Conductivity, Total Dissolved Solids, and Temperature), total mineral acidity, total <br />recoverable metals, and dissolved metals were measured. Results of this test indicated <br />that each recipe effectively removed all the metals with the exception of Fe and Mii that <br />showed elevated concentrations in the effluent when compared to the influent water. <br />Overall, ph and Ca increased and redox changed from an oxidizing (>0 mV) enviroiunent <br />in the influent to a more reduced (<0 mV) environment in the effluent water. <br />1.2 Introduction <br />In an effort to improve water quality impaired by AMD within Colorado Gulch and <br />ultimately the Arkansas River, Colorado Mountain College Natural Resource <br />Management (CMC NRM) has assessed the water quality parameters of both Gulches <br />and the Lake Fork (CMC NRMI, 2004) and were able to provide base line data against <br />which the efficiency of the test cells will be measured. While the use of wetlands for the <br />treatment of AMD is a relatively new strategy, research and successful mitigation <br />projects has demonstrated that in some instances it is an appropriate and cost effective <br />alternative to traditional water treatment facilities. The US Bureau of Mines estimates <br />that over 400 wetlands have been constructed for the purpose of AMD treatment. AMD <br />treatment with natural and volunteer wetlands has shown to substantially drop sulfate and <br />iron concentrations by levels of 28% to 99%, depending on the physical and biological <br />variations that exist within the wetland (NRMI, 2002). <br />With the help of James Gusek (Golder Associates h1c.) and the Colorado School of <br />Mines, CMC NRM constructed asulfate-reducing bioreactor bench test consisting of five <br />cells with different substrate recipes and a control, in an attempt to determine the most <br />effective substrate combination for the removal of metals from Colorado Gulch waters. <br />This bench test was performed in a controlled environment on the CMC campus and <br />Colorado Gulch water was added to each cell simulating a flow thru wetland. The control <br />is included in this test to account for any contamination that may be introduced via the <br />substrate materials used in the cells. Effluent water quality parameters of pH, <br />Temperature, TDS, Redox, and Conductivity will be collected daily, and aliquots for <br />metals analysis was collected once a week over an 8-week period. The effluent aliquots <br />were submitted to a contracted independent laboratory for acidity, sulfate, total <br />recoverable metals and dissolved metals using standard EPA analysis techniques. <br />