THAMES Water has encountered further complications in its repair of Folly Hill’s collapsed sewer, with the works now expected to take at least an additional two months to complete.

The utility company had been making fast progress after assessing in mid-February that a 180-metre section of pipe in Farnham Park will have to be dug out and “replaced in its entirety”.

However, it discovered this week that a further 70-metre stretch of pipe at the northern boundary of the park was not upgraded in 2007/08, as was thought, and also requires replacing.

This will necessitate additional engineering works close to some of the park’s oldest oak trees - although Thames Water hopes to avoid an “open excavation” to minimise disruption to the trees.

Julia Potts, the councillor for Upper Hale who has liaised closely with Thames Water and residents throughout the works, said: “This section runs past some of the oldest and finest veteran oak trees in the park and Thames Water have agreed in principle to replace this section using a so-called ‘pipe bursting’ technique which will install a new pipe through the existing line without the need for excavation.

“This work will not take any longer than an open excavation and will have minimal impact on the roots of adjacent trees. But it will of course mean that the project will last longer than anticipated and although no actual timings have been agreed we suspect this further work will mean Thames Water will be on site for about a further two months.

“While clearly not ideal that the works will take longer, I think we would all agree that it is however far better to rectify all issues with this pipe run now rather than leave it and so this is a delay that will be worth it in the long term.”

Miss Potts added Thames Water and its contractors have started the investigation works into the remaining pipe runs in the park to obtain “a full picture” of all further potential issues. The results of this investigation work will need to be analysed and, warned Miss Potts, “there is still the potential for further works to be required in the park”.

A temporary HGV trackway has been in place between the Sandy Nook estate and the work site in Farnham park since mid-January to facilitate the sewer works, but there are currently no plans to extend this.

Waverley’s senior ranger also has a site meeting with Thames Water on March 8 to review progress and the plans for restoration following completion.

Miss Potts continued: “The return of the park back to its prior condition will be an involved, complex process and Waverley officers and rangers will be on site to ensure there is no further damage to tree stock while the temporary track is pulled up and removed.

“While no time frame has been agreed by Thames Water, given the various complexities of the work we estimate the ‘pipe bursting’ will be completed around the early part of March and the track removal commencing about the same time.

“The track removal should take no more that a month and we would suspect quicker but its very difficult to gauge at this time. In all and so long as no further works are identified we are hopeful we are within eight to 10 weeks of Thames Water being off site.”

It comes after human excrement and other detritus was seen gushing out of a manhole cover in Farnham Park in mid-December 15, flooding public footpaths and polluting the Nadder stream feeding into the River Wey.