Currently the utility is about halfway through its 2025 programme and is in the midst of working on L’Aumone, which is currently shut.
The utility undertakes surveys of manholes, chambers and covers each year.
Sewage generates gas, which is corrosive, even to the concrete in the chambers.
‘Over time this corrosion could lead to the chamber suffering a sudden and pretty catastrophic collapse or blocking the sewer and potentially meaning a localised flood of unmentionable stuff until we could divert the flows,’ a Guernsey Water spokesman said.
‘Obviously, this is the scenario we are trying to avoid. And that’s why this work is taking place.’
The utility’s work is seeing new concrete chamber lids created, the brickwork repaired and then the concrete protected with a coating to help stop it softening over time.
L’Aumone is shut between the traffic- light junction and Courtil Simon Lane until Tuesday 30 September. It follows on from a closure of nearby Mont D’Aval at the end of the summer.
‘We’ve also done some good old-fashioned engineering at the junction of Les Beaucamp and Mont D’Aval – taking the chance to upgrade it and better managing the flows at this critical point within our wastewater network,’ the spokesman said.
‘This is actually a major intersection within our wastewater system, before heading towards Belle Greve Wastewater Treatment Works.
‘This location was a serious pinch point. By installing extra pipework we’ve made the flows – which arrive separately – join together better and not at a 90-degree turn. Previously they were forced together, slowing down flows and leading to the possibility of flooding.’
The rolling programme of investment will continue each year.
‘Although closing main roads causes inconvenience, it’s less disruptive than emergency closures due to collapsed chambers which would take longer to repair,’ the spokesman said.
‘It’s safe to say most people probably don’t think about the 300km of wastewater pipes that are beneath our feet, working 24/7, 365. But we do.
‘And thanks to upgrades like this, that network is going to keep on delivering.’
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