Case Study

Punta Penna Purifier – Vasto (CH)

Consolidation of digester foundation soil by laying piles

Structure: water collection tank purifier located in the municipality of Vasto (CH) locality Punta Penna, with structure at the base made of steel-clad concrete and steel elevation part.
Foundations: from the assays carried out in advance by our specialized technicians, a reinforced concrete slab foundation having a thickness of 70 cm was found. Breakdown: failure of the strtutra occurred during the flood test in 1980 that made the structure unusable as there were failures exceeding the allowed tolerances.
Soil: as a result of investigations carried out by the client, heterogeneous topsoil, vegetable soil and altered colluvium were found in the uppermost layer (from p.c. down to -4 / -7 meters deep), followed by underlying layers consisting of fine-grained sands, silts and clayey silts with sporadic gravels.
Request for action: consolidation of the foundation of the sewage treatment plant to secure the structure.

The Project

Intervention: consolidation by driving 222 MP60 steel micropiles (Product CE marked according to the European standard EN1090-1:2009)
Depth reached by the micropiles with respect to the foundation laying surface: from 8 to 12 meters.
The intervention required the use of trained personnel with special equipment for confined spaces, accessing the site area only by a 1m diameter valve.

Type of foundation: reinforced concrete slab.
Depth of foundation: 70 cm.
Average depth reached by the micropiles with respect to the intrados of the slab: 8-12 meters.
Average driving pressure: 230/240 bar corresponding to strengths greater than 220 kN per driven micropile.
Duration of consolidation work: 7 days.
Number of operators used for the work: 5 skilled operators.