Leak-tight thanks to MC injection technology

• Name

  São Paulo sewers sealed with MC injection technology

• Country

  Brazil, 2022

• Fields of Expertise

  Sewage water

• Categories

  Injection Systems
  Joints & Sealants

• Products

  MC-Injekt 2133

The Tietê Project is considered one of the largest wastewater infrastructure development undertakings in Brazil. Since 1992, 1.8 million sewage connections have been installed in the São Paulo metropolitan region, with some 5,000 km of pipes and channels having been laid to collect wastewater underground and transport it to the region’s sewage treatment plants. As part of this network, the second section of an interceptor sewer was installed along the banks of the Tietê River in São Paulo in the mid-2000s. However, this was only connected to the main system in 2021 as part of the ITI 2 project phase. The remit included the construction of new manholes and sewers and their connection to the main interceptor, as well as the sealing of all leakages between the concrete joints. The client and planner was the company SABESP, which is responsible for both water supply and sewage disposal in 375 municipalities in the state of São Paulo. SABESP is regarded as one of the largest sewage utilities in the world. The construction and refurb work was entrusted to the AEE ITI 2 consortium comprising three São Paulo companies specialising in wastewater infrastructure: Aliter, Enpasa and Etesco. SABESP’s main concern was, firstly, to prevent any leakage of wastewater into the subsoil in order to ensure the long-term stability of the sewer pipes and the road above, and secondly, to stop the infiltration of groundwater into the sewers and thus reduce the amount of wastewater requiring treatment.

Permanent sealing achieved with two-stage injection

To this end, two sewer pipes, both with a length of around 1,500 m but with a diameter of 1.5 and 1.2 m respectively, had to be sealed. MC was able not only to offer a package of high-performance products, but also to provide a fast, practical, two-stage injection process for the permanent waterproofing of cracks and joints in the sewer pipes – without impacting on the road traffic above. Using MC’s proprietary injection technology, MC-Injekt 2133 was injected in the first of the two stages. This single-component, rapid-expansion injection resin is used to stop fast-flowing water and so temporarily seal water-bearing cracks. And it met this remit perfectly in the ITI 2 project. MC-Injekt 2133 is characterised by its fast reaction on contact with water and stops pressing water almost immediately due to a high-volume swell achieved within a few seconds. The second phase involved injecting the ductile resin MC-Injekt 2300 NV. This low-viscosity elastomer compound is easy to apply at low injection pressures. Due to its low surface tension, it is highly penetrative while maintaining a high degree of elasticity within the crack once fully cured, ensuring permanent watertightness of the injected areas. The project in São Paulo began in February 2020 and was completed in December 2021. Around 70,000 litres of MC injection resin were ultimately applied to around 30,000 linear metres of transverse and longitudinal joints and cracks.