Transportation integrated Storm Water Management

Guidance for the planning and implementation of comprehensive storm water quality and quantity management for streets and highways in North Central Texas is now available.  This guidance has been added as an appendix to the integrated Storm Water Management (iSWM™) Design Manual for Site Development.  Appendix J, “Transportation integrated Storm Water Management (TriSWM)” may be used by cities, counties, and transportation agencies in the planning and design of storm water management systems for transportation infrastructure projects. 

Most of the original iSWM™ Design Manual for Site Development, including hydrologic analysis, hydraulic design, and most best management practices (BMPs), is applicable to transportation projects.  However, the planning of water quality controls for streets, roads, and highways is somewhat unique due to the linear nature of the projects.  For linear transportation projects, Appendix J is to be used in place of Chapter 1 (Storm Water System Planning and Design) and certain sections of Chapter 5 (Storm Water Controls) of the iSWM™ Manual.

The TriSWM water quality criteria establishes recommended storm water BMPs based on the projected traffic volume of the roadway and the Texas Commission on Environmental Quality’s water quality designation for the receiving stream or reservoir.  The lowest treatment level calls for one or more BMPs from a list that includes scheduled street sweeping, open drainage with grass channels, and filter strips among others.  Options in the higher treatment level designations include enhanced swales, bioretention areas, wet ponds, constructed wetlands and infiltration trenches.  The TriSWM planning and design approach calls for early consideration of storm water management issues so that adequate right-of-way may be acquired for structural BMPs if necessary.

For information on this project, please contact the Project Coordinator, Jeff Rice, at jrice@nctcog.org or (817) 695-9212.

Download Appendix J, Transportation integrated Storm Water Management