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<br />10 <br /> <br />Phase 1, planted primarily with bulrush <br />plants, will filter out sediments and remove <br />nutrients and organic materials by nitrifica- <br />tion (bacteria converting ammonia to <br />nitrite and then to nitrate) and denitrifica- <br />tion (the addition of carbon to convert <br />nitrate to nitrogen gas, which will escape <br />from the system into the atmosphere). The <br />plants or the soil sediments will also ab- <br />sorb additional nutrients and some metals. <br />Phase 2 is primarily for wildlife use, which <br />will degrade the water quality in some re- <br />spects (e.g., from feces, feathers or other <br />remains, sediment mixing, possible patho- <br />gens brought in by the wildlife, etc.). Phase <br />2 may also help improve the water quality <br />by providing oxygenation of the water for <br />further nitrification, additional nutrient re- <br />moval by the submerged plants and algae, <br />destruction of pathogens by the direct sun- <br />light, a sink for sediments or phosphorus, <br />and/or equalization and mixing of the <br />water flow. Phase 3, again planted primar- <br />ily with bulrush plants, will remove the <br />nutrients and algae which may accumulate <br />in the open water pond and will allow extra <br />time for denitrification. <br /> <br />The original outline of the Hemet wet- <br />land mimicked a natural wetland config- <br />uration in which several tributaries con- <br />verge into one to become an open water <br />area. However, the original outline <br />required some downsizing to fit all the <br />treatment arms into the 45-acre rectangle <br />which EMWD had available. The new <br />configuration resembles a baseball glove. <br />In any case, wildlife prefer a natural shape <br />over square comers; each wetland part can <br />still function as conceptualized. <br />To test the hydraulics of the proposed <br />wetland shape and the arrangement of the <br />wildlife features which will be built into it, <br />Russ Dodge of the Hydraulic Structures <br />Section tested the design with a table top <br />model in the Hydraulics Laboratory. The <br />model made obvious the effects of every <br />island or deeper water area on the water <br />flow. Russ changed the inflow configura- <br />tions to obtain a more even flow across the <br /> <br />treatment arms and, with the rest of the <br />technical team, changed the shape and <br />placement of the islands and associated <br />deeper water holes to avoid large "dead" <br />areas. No exchange of air or water takes <br />place in dead areas, so the water becomes <br />stagnant, or nearly so. Stagnant areas do <br />not contribute to water quality improve- <br />ment, nor will wildlife use such areas. The <br />aquatic invertebrates that are eaten by <br />many waterfowl and aquatic birds will not <br />thrive, and pathogens, like Clostridium bo- <br />tulinum, the bacterium which releases a <br />toxin that causes botulism, may flourish. <br /> <br />! <br />1 <br />'I <br />1 <br /> <br />This 20-acre demonstration wetland has <br />been designed not only to clean the water <br />to acceptable levels and provide wildlife <br />habitat, but also to provide a perfect oppor- <br />tunity to conduct research on all types of <br />constructed wetland issues. For example, <br />the system will be flexible enough to con- <br />duct studies on variations in the loading <br />rates, flow rates and retention times for <br />treatment, and detenninations of treatment <br />effectiveness in each wetland zone. Re- <br />search will also be conducted to detennine <br />how the size, orientation, and placement of <br />islands affect waterflow and use by inverte- <br />brates and wildlife. Wildlife use and the <br />sUlVivability of various wetland plant com- <br />munities will also be studied. Many other <br />research issues exist, and more may be ad- <br />dressed as time goes on. Additionally, <br />eight pilot cells have been built near the <br />demonstration site to test specific research <br />issues in a more controlled environment. <br />Questions answered in the pilot cells will <br />enhance the effectiveness of the demonstra- <br />tion wetland and future operational <br />wetlands. <br />Many Denver Office scientists and engi- <br />neers and Lower Colorado scientists and <br />planners worked with EMWD personnel <br />on this project since its inception. If you <br />would like to obtain more infonnation, <br />please contact Ms. Bernice Sullivan, Activ- <br />ity Manager, at 303-236-3171. . .. <br /> <br />- <br />