The works were part of Snam Rete Gas’s “Vaprio d’Adda Network Upgrade” project, which involved laying a new DN 200 (8″) pipeline for a total length of 8 km in order to expand and decommission the existing pipeline. The existing pipeline was attached to the Canonica d’Adda bridge structure. In order to limit any potential risks and minimize impacts, Snam Rete Gas planned to use NO-DIG technologies for the new Adda River crossing project.

• Duration: 90 days, in accordance with the contractual work schedule
• Average production: 18.5 m/day
• Maximum production: 33 m/day
• Maximum thrust: 620 ton
• Average thrust: 420 ton

The technology initially selected had been TOC, which was later replaced with Direct Pipe due to difficulties in executing the pilot hole because of the heterogeneity of the soil traversed. The launching ramp was prepared by installing the rollers on 16 concrete pillars, which were cast in place at a distance of about 15m from each other. The height of the launching ramp varied between 2.2m and 0.97m from ground level.

Intervention characteristics

• Difficulties in continuing the execution of the pilot hole planned in TOC technology
  • Suspension of work in progress due to choice of NO DIG technology change.
• Geology consisting of loose gravels and sands, near-surface aquifer
  • Construction of starting well at shallow depth
  • Construction of a 24 m long, DN 1800 jacketed pipe to ensure adequate coverage at the start of drilling, minimizing the risk of spills and leaks of mud into the ground
• Geology consisting of loose gravels and sands
  • Special attention to the lubrication fluid to be injected into the overburden to keep thrust forces within allowable limits
• Complex logistics
  • Placement of reinforced concrete box culverts in order to cross the irrigation ditch that ran through the site and ensure vehicle transit and roller placement