Protection and erosion control of embankments at the Planais pumping station

Filter Unit® for embankment erosion, Planais

Filter Unit®: geocontainers for embankment erosion control.

Problem

In May 2012, the new Planais water pumping station was inaugurated. The station was built to prevent flooding in the industrial area of Aussa-Corno. The planned hydraulic works include two separate systems, for rainwater and wastewater, as well as various open-air channels for rainfall. They also include a pumping station for managing water across the district.

The existing Planais pumping station had become insufficient for the new discharge rates. For this reason, a new modular station was planned, built alongside the existing one. The new station will be activated in successive stages, running in parallel with the existing plant.

Following installation of the new pumps, it became necessary to protect the river banks downstream from the station. However, the banks upstream also required adequate protection, due to the thrust caused by the bend in the riverbed. For this purpose, engineers chose to build a structure capable of resisting the water thrust. The structure also had to guarantee high durability in water and under UV exposure.

The project also required:
• rapid installation, even in the presence of moving water;
• flexibility and adaptability to any unevenness in the laying surface;
• the possibility of using smaller stone material than traditional rip-rap, including sharp-edged stones, easily sourced on site.

Solution

All the characteristics listed above were found in the two-ton Filter Unit® elements. Once filled with stone, these containers measure 0.4 m in height, 1.90 m in diameter, and have a volume of 1.24 m³.

Two cross-section types were designed. Type A is placed downstream from the pumping station and consists of 4 elements of 2 tons each. Three elements are stacked, while one is placed on the side, in contact with the embankment soil. Type B, instead, is placed upstream from the plant and consists of three stacked elements, held in place by a piling.

The inert fill material used for the Filter Unit® elements was easily sourced locally. This kept installation time to a minimum, with good results. The Filter Unit® elements blend perfectly into the natural environment and promote revegetation along the water-soil boundary.