Lake Lenexa is under construction in the western portion of Lenexa, Kansas, amongst existing neighborhoods and subdivisions. Because of the urban setting, design factors had to be weighed against cultural factors. As the key component of the "Rain to Recreation" program, the project captures storm-water in upstream wetlands to remove sediment and improve the water quality of the reservoir. Flood protection, water quality improvement, and recreation are the main purposes of the dam and reservoir. Community involvement was required at all stages of the project. Design factors to increase the benefit to the community, such as stream restoration projects, development of fish and wildlife habitat, hiking trails, wetlands areas, fishing, non-motorized boating, parks, and recreational facilities, were incorporated into the project. Existing stream and riparian areas were replaced with shoreline improvements along the lake. The effects to downstream habitats were minimized by providing stream flow augmentation. Because of the high visibility of the dam and reservoir, aesthetics played an important role in the design of the dam, bridge, and spillway sections. Architectural plans for the spillway structure and bridges, landscaping plans, and recreational trails were coordinated to maximize the benefit to the community. A Value Engineering (VE) study was performed to determine cost-effective means to implement architectural features within the spillway. An innovative use of mechanically stabilized earth (MSE) retaining walls, normally used in transportation projects, was designed as an alternative to the original cast-in-place counterfort wall systems, providing gravity walls in the main spillway and stilling basins. A unique application of mixing borrow clay soils with cement-kiln dust (CKD) provided support for the spillway structural slabs and project features. The distinctive properties of the CKD material were low compressibility, high strength, and low permeability, which reduced seepage and uplift pressures under the spillway slabs.
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