L’Aquila post-earthquake reconstruction

Ecopal corrugated pipes and moulded base manholes

Following the calamitous events that struck the province of L’Aquila in April 2009, the ForCase Consortium recognised 19 areas in the vicinity of L’Aquila where new housing was to be built to accommodate 12,000 people.
Ecopal high-density, polyethylene corrugated pipes were chosen and laid for the construction of the urbanisation of the new neighbourhoods and, in particular, for the white-water sewerage system.
The diameters used range from ND/OD 315 to ND/ID 800.
Polieco Group’s polyethylene products were also chosen as complementary elements along the network (manholes, gully pots and couplings).
Specifically, the following were used:

  • Moulded line or three-inlet manholes produced by rotomoulding procedures for pipes up to ND/OD 630 diameters.
  • Manholes made from corrugated pipes for pipelines of ND/ID 600 diameters and over.
  • Injection-moulded ND/OD 160 couplings that can be connected directly to main pipelines or manholes by simply drilling holes in the main pipeline or manhole riser.
  • Rotationally moulded gully pots with a ND/OD 160 outlet that can be connected directly to main pipelines or manholes using the system described above.

The reasons that led Civil Protection Department engineers to choose plastic products are technical on the one hand and logistical/organisational on the other.
Corrugated polyethylene pipes not only have outstanding technical specifications (resistance to abrasion, resistance to chemical substances, flexibility, lightness, and versatility) but also show remarkable adaptability to ground movement caused by landslides, mudslides or earthquakes, owing to the visco-elastic properties of the polymer that distinguishes the raw material.
The use of corrugated polyethylene pipes is particularly advantageous in the presence of lateral movement – although there is little space between the inner pipe and the coupling, which is sufficient to position the lip of the gasket, they are able to absorb seismic stress in the transverse direction owing to the deformability of the coupling system, which allows values of 5%.
Another fundamental characteristic in the case of seismic activity is also the length of the socket – corrugated polyethylene pipes are connected by means of a coupling/socket which is considerably longer compared, for example, to a concrete pipe – the coupling system designed by Polieco Group is able to tolerate axial motion of between 100 mm for a ND/OD 315 pipe and 165 mm for a ND/OD 800 pipe.
The gasket is also housed in the space between two corrugations, which prevents it from escaping during assembly or during any ground movement.
The length of the coupling also makes it possible to use two gaskets on each side in order to augment the system’s watertight seal.
In addition to these technical reasons, there are also a number of logistical features that are key in the case of exceptional events, such as those planned for the reconstruction of the Abruzzo region. In this case, the contracting companies had a contractual period of sixty days, including Saturdays and Sundays to complete the installation and laying of pipelines for the water and sewerage distribution networks, including the associated connection of gully pots and drains for the new homes.
In this specific instance, the special characteristics of the corrugated pipes and polyethylene manholes, such as the length of the 6m bars, lightness, flexibility, ease of carrying out fittings, and the option of the creation of any special pieces, made the installation of the entire distribution network faster.
The watertight seal of the sewerage distribution network system made up of corrugated polyethylene pipes was then tested under the supervision and control of representatives of the Civil Protection Department, in accordance with reference standard UNI EN 1610, at a pressure of 0.2 bar, with decisively satisfactory overall results.

  • Date