The aim of this paper is present the solutions adopted to support an endangered Brazilian Pipeline at the Rio Grande crossing, located between the border of São Paulo and Minas Gerais states. The 20” pipeline was built buried by the entrenched method, by which a trench is made in such a way to assure a 1,5 m depth of cover to the pipe.

This river crossing is assessed by visual inspection by diving each five years. During the last regular inspection in 2023, two contiguous free spans were found out. Together they represent over 100m of free span, leaving the pipeline floating at more than 5m depth to the riverbed. The most probable cause of the free span is related to intense sand dredging activity down and upstream of the pipeline. The preliminary evaluation criteria indicated a high-risk situation and so emergency measures were immediately taken. 

The very first support measure taken was the submersed installation of 50 plastic containers  placed along the unsupported length to provide a buoyancy force to counteract the lack of support. After this emergency work, the Emergency Group decided that the pipeline operation was started again, provided monitoring measures were taken.

To improve safety to the pipeline until definitive solution were built, the Emergency Group decided that a temporary support with geosynthetic filled with fluid mortar should be built. Each support was designed like this: after plaining the riverbed to form a basis, a non-woven geotextile is spread, on which a geosynthetic mattress is laid and filled with mortar, to form a plain surface. Over that a big bag is laid and filled with mortar to achieve the necessary height to the pipe. The heights are, on either case, 2,1m, 3,1m and 4,2m. The total volume is about 180m³.