Constructed Wetlands Project Description
by Jay Martin, Virginie Bouchard, Tim
Granata, and Martin Quigley
Summarized from Waterman Agricultural and Natural Resources Laboratory |
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- Constructed wetland treatment systems are an alternative receiving increased consideration to intercept and renovate agricultural water discharges (Knight et al. 2000, Peterson 1998). These systems have been successfully applied to treat farm effluents with high nutrient concentrations, including flows from milkhouses
(Schaafsma et al. 2000, Tanner et al. 1998) and swine housing units (Hammer et al. 1993). These systems have also been successfully applied to treat and retain stormwater runoff emanating from agricultural settings (Hill et al. 2000, Guardo et al. 1995). However, the possibility of concurrently performing both of these functions with one constructed wetland treatment system has yet to be explored, and is potentially problematic. A new constructed wetland treatment system on OSU’s Waterman Farm will receive effluent from a nursery facility and agricultural stormwater runoff.
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- The first objective of this project is to test the ability of the Waterman Farm constructed wetland system to concurrently meet treatment needs of continuous effluents with high nutrient concentrations, and simultaneous treatment and retention needs of agricultural stormwater runoff. Frequent water quality sampling across the wetland treatment system will quantify changes of nutrient and suspended sediment concentrations as water moves through the system. We hypothesize that nutrient and suspended sediment concentrations will decrease within the wetland cells. Another concern regarding constructed wetland treatment systems are changes in treatment performance due to ecosystem dynamics (Berge et al. 1997, Craft 1997, Brix and Schierup 1989).
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- The second objective is to determine how vegetative and sediment dynamics interact with water treatment performance during the development of this wetland treatment system. Vegetative parameters including plant diversity, density, biomass, and productivity, and sediment parameters including mineralization (expressed as emissions of the carbon end-products, CH4 and CO2), and accumulation rate will be monitored within the wetland cells to accomplish this objective. We hypothesize that from the inlet to the outlet of each cell there will be gradients of decreasing plant density, and increasing species diversity. We expect to find gradients of decreasing sedimentation and mineralization from the inlet to the outlet of each cell.
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The constructed wetland treatment system on Waterman Farm consist of two wetland cells that receive effluent from a nursery pad and stormwater discharge from several buildings, parking lots, and green areas. With an innovative hydrologic design and the ability to manage water levels of the cells the system was designed to provide treatment and retention to these dissimilar inputs. The two cells are located south of the nursery pad and to the north of the stream that exits the farm across Kenny Road.
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