City of Austin Lady Bird / East 4th Street Drainage Improvements

This project included the evaluation of secondary streets, inlets, and pipe flooding conditions located in an older section of East Austin. The total system included more than 5,000 linear feet (LF) of storm sewer. Plummer delineated more than 100 sub-basins and performed hydrologic evaluations using HEC-HMS. The existing storm drain system, modeled using StormCAD, did not have the capacity to pass the 10-year storm event. An initial feasibility study of this area identified over $15 million in storm drain improvements, ranging in size from a 24-inch diameter line to a 10-foot by 6-foot box culvert, to meet City drainage criteria for the 25- and 100-year rainfall events. 

During a detailed planning study, Plummer refined the modeling techniques and developed a flow-split concept to better utilize the capacity of the existing system. Plummer completed the design of the first phase of these improvements, which included 2,600 LF of 9-foot by 6-foot box culvert, 6,500 LF of 66- and 72-inch diameter storm drains, and associated junction boxes, manholes, and inlets.