Collierville Stormwater Drainage Improvements
During heavy downpours, the intersection of North Rowlett and Walnut Street in downtown Collierville became completely submerged, with water entering a church at the northeast corner of the intersection. A2H worked with the town to investigate the causes of the chronic flooding and to correct its storm drainage system around the town square. The project team discovered the flooding was caused by two factors: 1) the high embankment created by railroad tracks of the Norfolk Southern rail system, and 2) the undersized culvert beneath the railroad.
The necessary hydrology and hydraulics as well as storm water modeling were completed by A2H. The firm then designed plans and drainage improvements to accommodate the 100-year drainage system. The solution selected by the team involved the installation of a 48-inch diameter culvert beneath the railroad. The installation method for the culvert utilized jack and bore. Because of space limitations and the desire to minimize street closures, easements were obtained from the U.S. Postal Service, several private property owners, and a permit from the Norfolk Southern to work in their right-of-way.
A2H also prepared the preliminary engineering report, which helped the town obtain a $1 million CDBG Disaster Recovery Grant for this project.