The TDDT system stems from the HDD (Horizontal Directional Drilling) technologies used to lay utilities (usually cables and pipes) underneath surface obstacles (watercourses, roads, railways, structures, buildings, etc.).
In turn, much of the technological equipment adopted in this sector comes from the oil industry.
Trevi applied the said technologies to the geotechnical field, thus benefiting from production potentials and positioning accuracy. The system developed is named TDDT (Trevi Directional Drilling Technology) and includes a number of devices that enable to drill small-diameter boreholes (50-200 mm) of considerable length (generally from 25-30m to a few hundred metres).
By using TDDT, boreholes can be drilled both above and under the water table, even combined with the use of a BOP (blow-out preventer), and drilling can be carried out in any direction (including vertical and horizontal directions).
The TDDT has been successfully used in some important Trevi jobsites for soil consolidation and waterproofing. Drilling can be either rectilinear or curvilinear. In the latter case, the radius of curvature depending on the diameter and thicknesses of the rods and casings used.
Drilling can be carried out in any soil type (cohesive or non-cohesive), including rocks. For this type of drilling, standard equipment is generally used (drilling rigs, pumps, rods), whereas more complex projects need specific equipment.