Seaman Bridge, City of Greeley, Colorado
During the flood event across the Front Range in September 2013, access to bridges owned by the City of Greeley were damaged due to high flows in the Cache la Poudre River. The bridges lie in Gateway Natural Area in Larimer County and provide public pedestrian access as well as private vehicle access to the Greeley-owned Seaman Reservoir. During design of the replacement bridges, subsurface investigations were used to determine the appropriate foundations designs while a hydraulic study was developed in the river channel to determine flows during major flood events. These flows were then used to ensure that the bridges were set high enough to allow large flood flows to pass under without obstructing the river or bringing damage to the bridge. The bridges themselves were designed as modular, single span vehicular bridges with concrete decking. Spanning 78 and 91 feet respectively, the two bridges will no longer require the original piers in the river for support, yet the piers are to remain in place to protect the river wildlife habitat that has developed over the past few decades.