By Lynda Myer
In order to decrease the impact of construction on communities, a proposed revision to the massive sewer project in St Louis, Missouri, that has been bided by the Metropolitan St Louis Sewer District (MSD) will replace two wastewater storage tunnels with a single tunnel. While the capacity of a single tunnel is due to remain the same 58-million-gallon storage as the two original tunnels (the Upper River Des Peres and River Des Peres Tributaries Storage Tunnel), the number of tunnel shafts required will be reduced, and eliminated a dewatering pump station. Additionally, a reduction of the need to purchase residential properties and easement acquisition, as well as allowing easier access in and out of construction areas will be enabled by this project.
Moreover, approval of the US Environmental Protection Agency will require for these changes.
Including construction of eight mainly deep rock tunnels and storage facilities to separate areas with combined sewer and stormwater pipes that lead to discharges of sewage into the Mississippi River and its tributaries, in order to advance the 25-year Project Clear to upgrade the city’s aging sewer system MSD is around 10 years into work. The intended scheme that’s valued is US$6bn, will result in no more than 94 million gallons of untreated overflow during four or fewer overflow events in a typical year. The scheduled date for commencing the full operation of this plan is the end of 2037.
While the digging process of Deer Creek tunnel with 6.2km length was completed in January 2020, currently construction of the 6.8-mile (10.9km) Lower Meramec tunnel – the longest tunnel in Missouri – and Jefferson Barracks, is undergoing.
Due to the encounter of TBM with challenging conditions, the tunneling process of Jefferson Barracks was suspended in September 2019.Following this, the TBM was recovered and a replacement TBM, designed to detect karst and other underground features, resumed work in May this year.
