Newport Landing / Bennington Dam
HDR, in association with Lamp Rynearson and Associates, completed the Newport Landing/Bennington Dam project. The project created a multi-purpose reservoir facility to be used for flood control, recreation, erosion control and to create an attractive amenity for a residential community.
The project required the damming of an unnamed right bank tributary of the Big Papillion Creek and inundating the tributary's main channel. A 6,500-foot-long earthen dam, approximately 54 feet above the valley floor was constructed. This dam impounds approximately 300 surface acres of water. In addition to the construction of the dam, the project includes the construction of four upstream detention basins, a pedestrian trail, a weir and pump station, and improvements to the Big Papillion Creek channel. Elements of the design included geotechnical investigation; hydrology/hydraulics analyses; flood control analyses; reservoir operations and water supply analyses; water quality evaluation; and wetland delineation evaluation, design, and construction observation.
The Big Papillion Creek floodplain was evaluated, the flood reduction impacts were quantified and a dam break analysis was conducted. The Big Papillion Creek channel was widened and vertical channel side slopes eliminated to improve channel stability and channel conveyance. Flood reduction impacts to the Big Papillion Creek and the unnamed tributary were quantified by comparing the design peak discharges immediately below the project before and after the reservoir facility was constructed. A dam break model evaluated a dam failure and predicted the dam-break wave formation and downstream progression.