THE MAGAZINE FOR THE DRAINAGE, WATER & WASTEWATER INDUSTRIES
MAIN FEATURE
wipes and other unsuitable things being flushed into the system. In a previous issue we highlighted some of the unbelievable items found in our sewers, from laptops to guns to snakes. A fatberg the weight of three double decker buses was recently dealt with in East London at Abbey Mills pumping station by Thames Water and described in our June issue. The UK Government recently banned the sale of wet wipes containing plastic as these along with sanitary products, oils, fats and greases, are responsible for most fatbergs. Restaurants do get fined for blocking drains, but all these modern-day challenges only add to an already creaking infrastructure. Campaigns like ‘bin it, don’t block it’ and ‘only flush the three Ps: pee, poo and toilet paper’ may have some effect but seemingly not enough.
The background Whilst we know that the UK has had a
FOLLOW US
sewer system of sorts for quite a long time, it used to be generally acknowledged that around half of our sewers had been built since World War 2 and around a quarter had been built between WW1 and WW2. But there are obviously other sewers older and newer than these.
According to Water UK there are over 500,000 kilometres of sewer pipes in the UK, just over a fifth of which are ‘combined’ sewers. That means that for 100,000 kilometres of those pipes, sewage from homes is combined with rainwater to run into drains in our streets and roads. Overflows were built into combined pipes to supposedly stop flooding during storms and extreme weather events and it is mostly these overflows causing the current controversy and outrage. But sewers also do leak and collapse from time to time.
Nick Orman is Principal Consultant in Pipe Networks at the Water Research
Centre (WRc Group). He is a Chartered Civil Engineer and Chartered Water and Environmental Manager who has worked in the sewerage industry for over 40 years. At the WRc he has carried out research into sewer inspection technologies, sewer deterioration mechanisms, failure analysis and hydraulic modelling, and has been responsible for – or contributed heavily to – many key publications and reports. He is therefore well qualified to talk about the UK’s sewer network.
Nick commented that from his experience the sewers in the worst structural condition are not always the oldest ones. “Ground conditions are probably the most important factor in how long sewers last. So, sewers built on running sand are obviously not going to last well and some ground conditions alter as changing weather patterns bring more challenges. Even in more modern times we have had to rebuild sewers in areas where ground conditions have had
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