Fox Run Sewer Project	Majestic Bluffs Campus Infrastructure	North Point Rec Area	Platte Sanitary Sewer Study	Swan Lake Restoration Project	West Yankton Sewer Feasibility Study

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West Yankton Sanitary Sewer Feasibility Study

Yankton County, South Dakota Yankton County and the West Yankton Sewer Development Committee wished to prepare a sanitary sewer feasibility study for the rapidly growing area near Lewis & Clark Lake west of Yankton, South Dakota. The proposed study area would encompass all or portions of approximately forty-five sections of land and fifty-six housing developments. The land used in the drainage basins ranged from agricultural to business, commercial, and residential. Each of the housing developments falls within one of eight natural drainage basins outlined in the study. The feasibility study was to address the existing housing and wastewater needs, the 20-year growth expectations, the identification of centralized sanitary sewer system alternatives, and the probable construction costs for the appropriate sanitary sewer system options. County officials also wanted the study to define the potential user hookup fees and monthly rates for providing and operating a central sanitary sewer system. Eisenbraun and Associates was selected to complete the feasibility study and assist with the subsequent public hearings and education phase. E/A began the study with a GPS survey to obtain key elevations throughout the project area. This survey aided in defining the drainage basin boundaries and determining the wastewater transport limitations. United States Geologic Survey maps for topographic reference and legal plat maps for property descriptions were also utilized throughout the study. The predominant method of treating wastewater in the study area was the utilization of individual septic tanks and/or tile fields. Over 625 homes or businesses in the West Yankton area were generating approximately 0.21 million gallons of wastewater daily. In the year 2015, population projections predict there will be 1,380 homes or businesses in the West Yankton area which will be generating approximately 0.53 million gallons of wastewater daily.

Three wastewater transport alternatives were considered: gravity, pressure, and vacuum sewer transport systems. The advantages and disadvantages for each transport system were detailed and the construction, operation, and maintenance costs were compared for each alternative. Also considered were three wastewater treatment alternatives: utilization of the City of Yankton’s waste- water treatment plant, utilization of a wastewater lagoon and artificial wetland, or the utilization of a wastewater lagoon and rapid infiltration basin. At the conclusion of the feasibility study, Eisenbraun and Associates provided recommendations and a plan of implementation to the West Yankton Steering Committee.