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I)esigning Wetlands to Clean Wastewater 8 In the midst of the 1990 California drought, EMWD (Eastern Municipal Water District), located southeast of Los Angeles, became interested in reusing their scarce water supplies. The progres- Reclamation/Eastern Municipal Water District Multipurpose Constructed Wetlands JOAN S. THULLEN Applied Sciences Branch sive Managers and Board of Directors decided to try constructed wetlands, a cheap and relatively new biological tech- nique, to clean their secondary treated municipal wastewater and simultaneously provide green space and wildlife habitat. EMWD brought their idea to Reclama- tion. Reclamation felt that a constructed wetland research and demonstration pro- ject would be mutually beneficial, and a Memorandum of Understanding was signed. Technical teams from EMWD and Rec- lamation created conceptu'al designs for several types of wetlands. Civil engineers, hydraulic engineers, chemical engineers, soil scientists, a geologist, a botanist, a landscape architect, and a wildlife biologist worked together to move from a wetland concept to the final design phase. Construc- tion of the first demonstration wetland will begin in early 1994 at EMWD's Hemet/San Jacinto Regional Water Recla- mation Facility, or simply, the Hemet site. The 45-acre site will include about 20 acres of treatment wetlands, some riparian areas, moist soil wetland areas, native up- land grass and coastal sage shrub areas, and areas for public viewing, parking, walking, picnicking, and passive recreation. The goals of the Hemet wetland are to improve the quality of the wastewater to allow its use for agricultural and landscape irrigation, or for ground-water recharge, and to provide diverse wildlife habitat I --I .J I I I (particularly for migratory waterfowl and other wetland birds) and greenbelt aes- thetic areas in a semirural, urban setting. The bottom line is to achieve these goals in a more cost-efficient manner than con- ventional water treatment methods and to improve the San Jacinto Valley environ- ment at the same time. The conceptual design for the Hemet demonstration site was developed by studying the published literature on con- structed wetland design and interviewing experts in the field. The USBR/EMWD Phase 1 Report (November 1991) explains the conceptual design in detail. The design is based on a three-phase system concept. Each phase has a particular function and retention time to achieve the stated objec- tives. This three-phase system, developed by Dr. Robert Gearheart of Humbolt State University to treat 1 million gallons of water a day, consists of the following components: .. .~ 1. A to-acre treatment wetland, which the water moves through in 5 to 10 days. 2. A 2- to 3-acre open water pond, which the water moves through in no longer than 2 to 3 days. 3. A 6-acre "polishing" wetland, which the water moves through in 4 to 5 days. - I I