Renewal of Water Main, Leicester
As part of a £5 million scheme carried out by Severn Trent Water to renew the water main and secure future water supplies, a large section of underground water pipe was replaced beneath Anstey Lane, one of the busiest highways in Leicester.
From Gorse Hill Junction to Gilroes, Leicester
T500 Series 3 TracStar and accessories plus Powered PolyHorse Pipe Loading System
The work was carried outfollowing a burst water main and associated flooding on the stretch of road earlier in the year. Radius Subterra were tasked with the replacement of an existing 20” cast iron main with 500mm polyethylene (PE) pipe.
The existing water main was a 20” cast iron main, which was coming to the end of its lifespan due to corrosion and becoming structurally weakened. It was decided to replace the main with 500mm PE pipe using Radius Subterra’s Subline Diameter Reduction (DR) method of inserting pipe. This involves the use of revolutionary close-fit pipe rehabilitation technology, whereby the PE pipe is reduced by 10% of its original size for insertion. Once inserted, the pipe is pressurised using cold water to revert it back to its original diameter and form a close-fit against the bore of the original mains pipe, providing maximum flow capacity within the pipeline. Due to the location of the existing main running under a main highway into Leicester, open cut methods to replace the main were not an option.
Radius Subterra were able to use the Subline DR method alongside equipment provided by PSS HIRE’s Wolverhampton depot, to slipline the existing water main with pipe that had been reduced in size from 500mm to around 450mm. Firstly the existing main was cleaned and scraped to allow easier insertion of the new pipe. The 500mm PE pipe was then butt welded together using a S3 T500 TracStar and powered PolyHorse system supplied by PSS HIRE.
The S3 T500 TracStar is a fully automatic machine, whereby the facer and heater plate are mounted to the machine, and are self-powered by the machine. It was the ideal piece of equipment for this project and the conditions in which Radius Subterra had to weld the pipe, as the TracStar is an all-terrain Butt Fusion Machine mounted on tracks, making it easily manoeuvrable across site. A powered PolyHorse Pipe Loading System was also hired for the project. The PolyHorse consists of a series of adjustable racks able to store the pipe direct from the delivery truck. It has a hydraulically powered roller to help lift and manoeuvre the pipe direct into the TracStar, presenting a much more efficient and safer way of loading pipe into the machine, and avoids unnecessary damage to the pipes.
Once up and running, the string of welded pipe was then pushed through roller sets to reduce the diameter of the pipe by up to 10%, thus making the pipe smaller in diameter to the existing cast iron main. The pipe was then pulled through using a standard winch and joined to the existing water main. Once installed the pipe was pressurised with cold water, returning the pipe to its original 500mm size. This ensured the pipe retained pipe flow capacity at 8 bar, and formed a tight fit to the original existing cast iron main.
This presented a much more cost-effective way of replacing existing aging water mains. By not having to open cut along the existing main, time, expenditure and man hours were saved. The pipe was able to be replaced by two small excavations; a small insertion pit and another to pull through the new pipe at the end of the old pipe being lined. This also ensured the works could be carried out as quickly as possible, with reduced disruption to local residents and businesses in the area.
“This was a faultless hire with very good service received from the team at PSS HIRE’s Wolverhampton depot.”
John Williams, Radius Engineering Projects Manager (Water)