by Margaret Medallin, HDR Engineering
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| Photo 1. Calhan Constructed Treatment Wetland |
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| Photo 2. Platteville Constructed Treatment Wetland |
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| Photo 3. Valmont Power Plant Subsurface Flow |
Historically, wetlands were considered wastelands that harbored mosquitoes, rodents, and disease. As a result, many wetlands were cleared to allow a path for urbanization. However, the loss of vast wetland acreage eventually brought attention to the ecological values of these overlooked and underappreciated areas.
One of the most crucial and valuable functions of wetlands is the natural cleansing of water. As water flows over the watershed it picks-up pollutants and carries them dissolved or in suspension towards the receiving water body. Wetlands are a natural filter in the hydrologic process. Debris is trapped in the slow moving waters of the wetland, plants utilize nutrients, the sun provides disinfection and microbial processes break-down other pollutants. Upon flowing out of the wetland, water has been cleansed from its overland journey and is prepared to enter the faster and clearer moving waters of creeks and streams. It has been found that the cleansing processes found in natural wetlands can be used successfully in the controlled environment of a constructed wetland.
As many Colorado towns experience population growth, they will need efficient methods for expanding their wastewater treatment facilities in order to meet increasingly stringent discharge permit requirements. Constructed wastewater treatment wetlands can be a very effective treatment process when incorporated into the overall treatment process. Governor Owens determined that it was in Colorado’s long-term interest to consider sustainability of natural resources when looking at infrastructure needs such as wastewater facilities. Therefore, approximately thirteen months ago Governor Owens directed the Office of Energy Management and Conservation (OEMC), under the leadership of executive director Rick Grice, to evaluate existing Colorado constructed wastewater treatment wetlands. The objective of this effort is to document “Lessons Learned” and evaluate the effectiveness of each wetland to meet its intended purpose. The final product resulting from the OEMC study will be a resource document for creating constructed wastewater treatment wetlands that will be effective in protecting the state’s water resources while reducing reliance on high energy technology. OEMC began its effort by compiling a Constructed Treatment Wetlands Task Force to provide expertise in guiding the effort and establishing the criteria for evaluating the wetlands. The Task Force includes representatives from the EPA, Army Corps of Engineers, Colorado Department of Natural Resources, Colorado Department of Health and Environment, Colorado Department of Agriculture, environmental organizations, land developers, wastewater treatment plant supervisors, academia, American Water Works Association, Water Environment Federation, United States Geological Survey, United States Bureau of Reclamation, Colorado Water Congress, and the Natural Resources Conservation Service.
The team of HDR Engineering and ERO Environmental Resources was selected to carry out the treatment wetland evaluation. Engineers and biologists from these firms have begun the process of collecting information on existing treatment wetlands. Site visits are being taken to evaluate the condition of each wetland. Much can be learned by ‘mucking-around’ in the wetlands. Natural systems will ideally take care of themselves. But it is vital that operators act quickly when the natural equilibrium is thrown off by such things as invading muskrats, excessive algal blooms, or mechanical failures. Operators of treatment wetlands are undertaking new management challenges in which conventional training must be augmented with botany, wildlife management, and trouble-shooting skills. Documenting problems that existing wetland operations have experienced, and the steps taken to solve them, will save time and money for future operations.
For more information regarding this project, please contact the OEMC project manager, Rob Pearson at 303.894.2383 .