Welsh Water set to tackle mini fatbergs in Mermaid Quay in 2 million investment

The work, which will start in September, will involve removing a mini “fatberg” from a Victorian brick egg-shaped sewer before starting to carry out needed repair work. Due to the sensitive location of the sewer in a busy, popular built-up area of Cardiff Bay, Welsh Water’s designers have been working hard to develop the most cost-effective, best-quality engineering plan to repair the sewer while causing the least disruption possible to local businesses, residents and visitors.

The sewer, which runs under Bute Street and Stuart Street in Mermaid Quay, was previously a large-capacity tidal sewer which was intercepted by the Bute Town Road Tunnels in the 1990s. The sewer now only receives a fraction of the flows it was originally designed for.

After incidents of internal flooding in the area, Welsh Water investigated and found the sewer in poor condition. The main cause of the issue was the build-up of fats, oils and grease in the sewer which often cause blockages in the system.

As a result, the company has had to regularly clean the sewer using high-pressure equipment, which is expensive, disruptive to the area and has speeded up the deterioration in the condition of the pipe.

The work is due to start in September and will be carried out in phases along Stuart Street and then Bute Street. We anticipate that the work on the sewer will be completed by March although some further minor works will then be required but these will be within confined areas.

Steve Wilson, Welsh Water’s Director of Wastewater Services said: “Around three quarters of all sewer blockages we deal with are caused by the wrong things being flushed down the toilet or poured down the kitchen sink and the condition of the sewer in Mermaid Quay reflects this. As a company, we have to respond to around 2,000 blockages a month and it costs us £7 million every year to deal with.

“In planning our essential work in Mermaid Quay, we have liaised closely with the businesses and residents there to explain to them why we need to do the work and what our work will involve. To minimise the impact, the work will be carried out in phases and we will also stop work over the autumn half term and during December to avoid the busy Christmas period. We would like to thank people in advance for bearing with us while we complete the work.

Mr Wilson added: “We always ask our customers to be careful about what they dispose of down the drains so that our sewers continue to operate effectively. We are working with the businesses in and around Mermaid Quay to make sure they have the right equipment in place to help them dispose of fats, oils and grease in the correct way to ensure that this doesn’t happen again.

“We are also running our ‘Let’s Stop the Block’ campaign which is aimed at encouraging people to help reduce the risk of pollution and sewage flooding by not putting fat, oil and grease down the drains.”