This project involved rehabilitating a damaged pipe in a busy area in Huddersfield. The section of pipe being repaired was on a cobbled side road off a busy main road. In order to complete this rehabilitation 10 metres of 300mm diameter liner was installed and cured using ambient cure technique.
This project commenced with the team reviewing the working area and carrying out the point of work risk assessment before any activity began. This was done to make sure that the risk assessment and method statement had identified and controlled all the significant risks. Any minor changes made due to site conditions were recorded on this point of work risk assessment and the team were briefed accordingly.
The team continued by ensuring that all traffic and pedestrian management was set out in accordance with the approved code of practice. In this project the pavement adjacent to the main road was kept open to pedestrians due to the busy road traffic. However, the relevant pedestrian management and segregation of the walkways were established and maintained to ensure the site remained safe.
Once the relevant traffic and pedestrian management measures were established the team then surveyed the sewer to be lined using one of our CCTV crawler cameras’. This enabled us to establish flow conditions, map connections, ensure the defects haven’t degraded further and assess cleaning requirements. The sewer was then jetted using a high pressure water jet, before a second CCTV survey was carried out to confirm the cleanliness of the sewer.
The team then prepped the liner, making small incisions along the full length of the liner, this is done so that a suction cup, connected to a vacuum pump could be attached over these small incisions, to aid an even impregnation of the liner. Following the impregnation, the liner was then cut to the required size with a meter left at one end to accommodate any spare resin.
The resin was then mixed in a well-ventilated area, one component at a time. A new component was only added once the previous component was fully mixed in. Once the resin was fully mixed it was poured into the felt, with the liner being held at 90° until the vacuum had taken hold. A small pinch roller was then used to ensure that the correct amount of resin was in the felt.
The air inversion method was then used to introduce the liner into the carrier drain. This is where the actual liner is wound onto the inversion drum and inverted through the drain using controlled air pressure up to (0.5) bar. This job also required the use of a calibration hose to aid the inversion of this liner from a single access point to a blind end. A calibration hose was introduced into the inner lining of the material and then the drum was sealed, air pressure (0.5 bar) is introduced into the drum. The calibration hose was then unwound off the drum at a controlled pace by turning the inversion drum wheel. Once the calibration hose reached the pre-determined measurement and the liner was up to its optimum size, the drum wheel was then tied off, ensuring a relatively tight air bag. It was now time to invert the liner. For this to be accurately placed in position a man had to enter the manhole. A small amount of pressure was put into the liner so that the operative in the manhole was able to feed it into position a small length at a time.
After the liner was installed our operatives had to wait for the ‘cure’ to take place. This is where the resin hardens and forms the new pipe within a pipe. The time which the liner takes to cure varies for each project but is continuously monitored to ensure that the time is assessed accurately. One of the visual checks undertaken is to monitor the mixing containers once the resin in those containers has fully cured, which for this project took 2 hours, was it considered to let the air out of the inversion drum. The calibration hose was then retracted from out of the newly cured pipe. For this project there were no lateral connections that needed re-opening.
A final CCTV survey was then undertaken on completion to ensure the installation and curing of the new liner had been a success. Following the completion of this CCTV survey the team took the site down and removed the traffic and pedestrian management in place.
Another successful project rehabilitating a damaged pipe using CIPP trenchless technology.