The project consisted of installing a new GRP (Glass-Reinforced Polyester) pipeline with an internal diameter of 1176 mm and a thickness of 26 mm inside the existing DN1300 concrete pipes, a methodology known as Sliplining.
In this type of solution, it is essential to ensure the filling of the remaining space between the concrete pipe and the new GRP pipe with a cementitious grout, in order to provide integrity to the system and protect it from undesirable movements.
Given the pipeline layout with changes in direction, and considering that the Sliplining rehabilitation method does not allow the execution of curved sections, it was necessary to divide the pipelines into three straight sections, with the creation of shafts for the introduction of the new pipes.
The entry shafts were precisely executed to expose the existing pipe and allow the removal of the upper section of the concrete pipe, leaving the lower section in place.
The major limitation of this methodology is precisely in the areas where there is a change in direction, as the lining can only be executed in straight sections, leaving a transition area and/or change in direction that always requires a complementary solution.
Thus, Mota-Engil ATIV opted for lining the transition zones with 3mm HDPE sheeting, mechanically fixed to the existing pipe and electro-welded between plates. Additionally, AMEX joints, made of EPDM rubber and a 316L stainless steel ring, were installed to reinforce the solution and ensure complete system tightness, as the pipelines operate under constant pressure of about 1.5 bar throughout 365 days/year. In total, 630 meters of the intake pipeline were rehabilitated.
A pioneer and reference in this field for about 20 years, for Mota-Engil ATIV, this was a major challenge as it continues to ensure the operational functionality of systems for key clients.
