Pinnacle Engineering was retained by a rail client to investigate complaints by a City and an area farmer whose land flooded following heavy rainfall. The City and farmer believed the flooding was caused by inadequate drainage capacity through two culverts on railroad property: an old cast concrete arch culvert running parallel to the rail client’s tracks and passing under a County Road; and a steel culvert leading from the city into a State Highway ditch and passing under the client’s tracks. Pinnacle’s client did not want to install additional culverts if they were not needed.
Pinnacle Engineering personnel conducted a site inspection and found that, although the farmer’s (and adjacent) property had seen only minor changes in the preceding 25 years, the farmer’s land and that of several nearby residents had experienced severe flooding. Pinnacle’s investigation also revealed that (1) the culvert that passed under the County Road had partially collapsed, reducing culvert capacity and (2) the adjacent State Highway had recently been reconstructed and that water appeared to be standing on the downstream side of the railroad’s culvert in the new highway ditch.
Pinnacle performed an engineering analysis, prepared a report of its findings, and worked closely with the rail client, County Engineers, City personnel, and area residents to find an acceptable solution for all.
Because the partially collapsed cast concrete culvert passed underneath a County Road, the County Engineer agreed to assume responsibility for replacing and thereafter maintaining the culvert.
Pinnacle determined through a hydraulic analysis that the steel culvert leading into the State Highway ditch was properly sized. However, the Iowa Department of Transportation’s reconstruction of the paralleling State Highway had not provided adequate ditch grade, and this (rather than an inadequately sized culvert) had caused an excessive tail-water and flooding to the City and the farmer’s land following excessive rainfall.