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State & Municipal Government

UPPER BEAL SLOUGH TRUNK
SEWER EXTENSION

LINCOLN WASTEWATER SYSTEM

City of Lincoln
Lincoln, Nebraska

EA was retained by the City of Lincoln to perform a basin study and preliminary design of wastewater collection system improvements in the Upper Beal Slough drainage basin, and to perform final design of the main trunk sewer in the Upper Beal Slough basin. The project included public involvement meetings, detailed topographic survey, geotechnical investigation, coordination with landowners, project cost estimates, and permitting. In addition, the project involved design and construction phase services for over 6,100 linear ft of 18- to 24-in. diameter trunk sewer. Project challenges included crossings of two railroad tracks, Pine Lake Road, 70th Street, Yankee Hill Road, and three streams. Tier I (25-year) and Tier II (50-year) service areas of the City’s Comprehensive Plan were analyzed, as were several alignments. Individual sub-basins were delineated in order to identify sewer reaches and to determine impact fees for potential development in the area. Several wetlands had been identified around the location of the project. Surface features were evaluated and included floodway and floodplain greenspace corridors, and land use. Subsurface soil conditions with groundwater close to the surface and the presence of wetlands made dewatering, trench stabilization for side slopes, and trench bottoms important considerations during the design process. Crossings under Pine Lake Road considered future expansion to a four-lane arterial urban roadway in design of manhole locations. Cost estimates and constructability analysis issues were evaluated as part of the alignment selection criteria.