'Limited knowledge' of Hertfordshire's drainage network could lead to failures, councillors told
Managing drains in Hertfordshire is a “reactive” job of the county council, members were told, as an officer said that most highways authorities have little knowledge of their historic underground drainage systems.
Members of Hertfordshire County Council’s highways cabinet panel met on Thursday to review a key annual document, the Asset Performance Report 2024-25 (APR), which shone a light on the council’s roads, footways and drainage systems.
It revealed the authority has 179,410 carriageway and footway gullies (drainage inlets) and 88 electric pumps. It acknowledged highways drainage does exist as buried pipework, but offered no further statistics.
The report stated: “HCC have a database of carriageway and footway gullies but limited information on other drainage assets, such as underground pipes, despite the large amount in existence.
“This currently means HCC cannot implement a planned cyclical cleaning or inspection regime on these other assets. This lack of regular maintenance could potentially lead to unexpected failures. Wherever possible, asset information is being collected during construction and maintenance works.
“Lack of up-to-date information on underground pipes and other apparatus is also a hindrance when faults occur or improvement works are planned.”
During the meeting, Cllr Steven Watson (Green, Ware South) said: “I would mainly touch on the footway, cycleway and drainage assets… I’m aware that this is 2024-25 data and we’ve had movements and policy since then.
“On the roads, there was a very proactive approach in maintaining them and stopping them getting into disrepair. There was quite a good knowledge base. I noticed this was lacking for drainage assets and footway and cycleway assets. We don’t really have as full a picture as perhaps we should?”
Chris Allen-Smith, head of profession, asset management & maintenance, said: “You are absolutely right the drainage service is much more reactive, and that is the usual way local authorities have to manage drainage.
“Part of the issue we have with drainage is that most of the assets are buried and we don’t necessarily know where all of them are in detail. We clearly know where the gullies are and we can map from the gulley’s downpipes to manholes, but most of those assets are buried.
“There were no historically kept records back in the day of where those buried assets were and that’s a national problem. Almost no highways authorities know much about their buried drainage assets.
“By their nature, drainage works tend to be very reactive. They are often not, I shall say, our problem. If a road is failing or a footway is failing, that’s all down to us. If we’ve got a massive puddle on a road, that may well be because a farmer has ploughed their field a different way this year, and the water is now running straight down onto our road and so a change in land use has generated a puddle where there wasn’t one before.
“Or it might be that there has simply been a lot of rain, the water table is high, all the gullies and road drains from there lead out into a watercourse or river or something like that. If the river has risen, then there’s nowhere for our water to go, so the water is sitting on the highway simply because it can’t discharge because the ditch or river is full.
“Drainage problems are often much more complex… there are some things that we do, routine cleaning out of the assets, checking things over… we have a lot of trash grilles, so that’s a grille going over a river or watercourse and it stops debris getting washed into a culvert or a bridge or something like that. If we have a storm forecast, we will go out and we will clear those trash grilles, they’ll clear any rubbish from them so that the water flows and we don’t get floods or a build-up of water.
“So there are things we can do to get ahead of the drainage game. I’d love to be able to do more, but it’s simply a case of it’s actually very costly to try and survey drainage assets. Even if the asset is in perfect condition, it might not function because it gets overloaded.”
Cllr Sandy Walkington (Lib Dem, St Albans South) said: “I smiled at your comment about buried assets. I used to work for utility and I’d put my hands up and freely admit we had no idea where half our underground cables were because they were put in at a time when it was a nationalised industry and nobody really bothered to record the information.
“I’ve just had an experience in my own division where residents planted trees and then suddenly went, ‘Oops, there’s a national gas pipeline there, have we done something we shouldn’t?’
“They got Cadent in and fortunately all was well because the pipeline took an entirely different route from the markers on the surface.”