DESIGN-BUILD OF THE NEW MISSISSIPPI STORM DRAIN OUTFALL, DENVER, COLORADO

This paper presents an overview of the New Mississippi Tunnel Storm Drain Outfall for the Transportation Expansion Project (T-REX). The Storm Drain Outfall conveys highway and other urban drainage to the South Platte River as well as provides long needed relief from flooding problems in the southeastern portion of the Interstate 25 highway corridor. The Storm Drain Outfall tunnel incorporates a one-pass precast concrete segmented liner to convey storm water under I-25 then under Mississippi Avenue to the river. The Storm Drain Outfall crosses both the existing I-25 as well as the future improvements including under the Light Rail Transit, a new bridge abutment, widened lanes, and new retaining walls. The Storm Drain Outfall also crosses adjacent to several buildings and five bridges, under major traffic and utility intersections, and through difficult geology.