Innovation in wet tunnel spoils management from MetaFLO

Tunnel construction is underway in every population center around the world and the need is only going to grow as densification and urban migration outpace urban planning, outdated underground infrastructure and capacity.

A report by the United Nations Department of Economic and Social Affairs estimates that by 2030, the world could have 43 so-called megacities (up from 31 today) – those with more than 10 million inhabitants – most of them in developing countries. Both the United Nations and the International Organization for Migration estimate that around 3 million people are moving to cities every week.

Jurisdictions each have their own unique set of development priorities, however, there are universal commonalities for underground tunnel construction that include:

• Transit expansion to address urban densification realities, workplace productivity and urban emissions criteria.
• Secure water and sewage movement in and out of population centers to replace and enhance aging infrastructure, address urban growth demands and climate change impact mitigation
• Commercial requirements for the flow of goods and services in and out of congested areas

Innovative technology has broadened tunnel application significantly:

• Improved geotechnical analysis provides better understanding of ground conditions
• Concrete linings allow for better bore wall stabilization and improved safety
• Sensors identify obstacles for better efficiency and less damage to existing infrastructure

Depending on ground conditions, the soil removed from the tunnel can be quite liquid. A mixture of clay and soil conditioners are utilized at the face of the tunnel boring machine (TBM) to lubricate, stabilize and extract cuttings out of the tunnel. This resultant slurry creates a problem for disposal.

Underground moisture problem

Spoils solidification with environmentally friendly polymers from MetaFLO Technologies provide an innovative and effective method to efficiently dry the wet spoils at the surface. Using purpose-specific mixing technology, engineered to match spoils output, MetaFLO’s polymer can simply be incorporated into the spoils and immediately transported to a receiving site requiring clean, dry fill in reasonable proximity of the tunnel site.

Clamshell tunnel slurry excavation

Planning is the key to a successful tunnel spoil’s management program – and the benefits can be significant:

• Reduced operational footprint in congested urban sites to manage spoils quickly
• Improved transportation efficiency to remove dry material from project sites
• Solidified spoils that meet regulatory criteria to go directly to clean fill sites
• Lower GHG emissions, improved urban logistics, responsible excess soil management

MetaFLO Technologies can work with tunnel operations personnel to help put together an effective plan to address the challenges of dealing with wet spoils.