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detrimental effects. Poor workmanship has also been an issue at times.”
He continued: “Water companies are still in the dark about some of their sewers, especially the smaller ones – unless they go wrong. In 2011 many thousands of kilometres of formerly private sewers were transferred over to the water companies and they still don’t know where all of them are. So, they are tending to wait until they need attention.
“Post-privatisation the focus was very much on the water distribution systems and a lot of work was done on the clean water system, but less on the dirty water system. Now, the balance of interest is moving towards sewers with the outcry on outfalls and sewerage discharge to rivers and seas.”
Four years ago, Nick wrote a blog about a scheme to improve a particular sewer in the early 1980s and how he was trying to improve the water quality of the nearby river. But the river inspector had already seen it improve from an original biological oxygen demand (BOD) of 165 mg/l – when everything in it was practically dead (even then the BOD of a discharge from a sewage treatment works was supposed to be below 30) – to a Class 2 river, and considered that as good as it was going to get. Yet there are always further improvements to be made.
“Back in the 1990s considerable money was spent on sewers but when we look at what is being talked about in the current storms overflow programme, you would now need to multiply that figure by about 1000. It all needs more money and skilled people too. Yet skills are a short resource across the industry. For example, in sewer operations, our sewer cleaning manual has evolved over the years to incorporate lots of research into how to clean sewers from those who have been doing it effectively for years. But some of the older skills have been lost by taking in new operatives once older ones retire or leave the industry as contracts change.”
Nick concluded: “SuDS offers part of the solution but incremental steps – replacing a bit at a time – are likely to be the only way to gradually improve things. Lining sewers is another solution with a
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lower carbon footprint. But the SuDS programme in the UK, whilst adopted by Wales and Scotland, has been stuck on the English statute books for 14 years without being implemented. If it had been implemented 30 years ago, then the scale of the problem we are now facing would have been much less.”
How to operate safely in sewers and drains
The WRc produced a Manual of Drain & Sewer Cleaning in 2020 which is regularly reviewed and provides an effective ‘bible’ of how to operate in drains and sewers. By clearly showing drainage engineers and others involved in how to correctly clean drains and sewers, the manual seeks to minimise the recurrence of blockages, to minimise adverse impacts on customers and to provide a cost- effective service. The WRc produces other manuals and guidance documents too, as do others involved in the industry, like the BPF Pipes Group, which provides technical guidance on the effective cleaning of drains and sewers, recycled bedding and surround for gravity drains and sewers, designing drains and sewers for brownfield sites, selecting and installing plastic inspection chambers for underground drain and sewer systems, connecting pipes to manholes and chambers, and even what to safely discharge into drains from domestic properties. It also provides specification documents for drains, sewers and even service ducts in highway applications along with leak tightness testing documents.
Pivotal to all of these manuals and documents aimed at helping keep our sewers functioning well and safely is correct training and installation techniques; the best product, method or system in the world soon becomes a liability if it’s not installed or operated correctly.
On a related subject, dealing with renovation and refurbishment work is another matter entirely and perhaps an even greater challenge due to the variety of what is beneath us in sewers and drains. Great strides have been made in lining underground pipe systems, a sympathetic way of renovating without
| August 2024 |
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having to dig out existing infrastructure.
Cured in place pipe liners (CIPP) have become one of the most favoured renovation methods for sewers. However, as with new build or renovation and refurbishment, the effectiveness relies heavily on the quality of the installation so appropriate training and best practice methods are always a huge factor. There are many organisations out there offering suitable training schemes, which would help mitigate jobs having to be redone due to faulty construction. This applies across all water and wastewater requirements.
Are there any simple or perfect solutions?
Very doubtful with the mish-mash of stuff down there in various stages of deterioration, but what could possible solutions to better protect our sewers include? The water companies have for years been trying to educate people in what not to put down the drain, but much of it goes in anyway. There are also the frequent attempts to get us all to reduce our water and wastewater use – the average person in the UK now apparently uses a stonking 150 litres of water per day (or the equivalent of 66 x 2.27-litre milk containers) – and reducing our usage would also save us money in terms of our bills. Water companies would like to get this daily usage down to 110 litres per day (just 48 milk containers). But standing charges have gone up everywhere and still the water
We each use the equivalent of 66 of these every day in water
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