Underground Detention in Historic Central Arlington Heights
Freese and Nichols’ innovative underground detention project in the historic Central Arlington Heights neighborhood of Fort Worth is currently being advertised for construction. This project included the design of a custom detention system underneath a flood-prone residential street in the historic neighborhood. The area had previously been studied by Freese and Nichols to determine the extent of the existing flooding and to identify solutions to eliminate flooding in a 100-year storm. The previous studies identified that 100-year solutions are not affordable and partial solutions that provide incremental flood benefits are required. The detention in Ashland Avenue was identified as an incremental solution that would provide a flooding benefit to the neighborhood. This project was selected to occur because a water and sewer project was planned for the street.
The design consisted of 345 feet of double box culverts extending from curb to curb below the street, providing approximately one acre-foot of detention storage. The box culverts range in size from 2-12’x4’ to 2-12’x9’. A custom diversion structure was designed to be constructed over the existing storm drain line constructed in the 1920s. The structure diverts high flows into the detention boxes for storage while allowing low flows to pass through. Due to cover constraints, the top of the diversion structure also serves as the driving surface of the street above it.
The project has included extensive coordination with the residents due to the historic nature of the neighborhood and the magnitude of the construction impact to the residents. Freese and Nichols is also designing a similar project two blocks away on Western Street. In addition, our team is continuing to work with the City to identify other incremental solutions in the watershed.