Oily slicks of kerosene still appeared to be leaking into the River Taff this week, several days after a breach of thousands of litres was spotted by members of the public.The breach into the Welsh river was identified last Friday, after people reported strong chemical odours emanating from the river. Natural Resources Wales (NRW) officers arrived on site soon afterwards to identify the source of the pollution and were assisted by South Wales fire and rescue service, which placed absorbent mats and booms to contain as much kerosene as possible.Residents along the River Taff in South Wales were advised to keep windows and doors closed last week, after it emerged that 1,000s of litres of kerosene from a GE Aerospace site in Nantgarw, Rhondda Cynon Taf had entered the river.

Four kilometres of waterway were affected, according to NRW.GE Aerospace is an American multinational company that designs and builds military and commercial aircraft systems and engines. Its site in South Wales is among the world’s largest maintenance, repair and overhaul facilities for commercial aircraft engines, employing more than 1,350 people.

In 2017 GE Aerospace was the recipient of £5m in funding from the Welsh government, intended to support innovation and sustainability in the aerospace sector.Despite early estimates of a volume of about 25,000 litres of kerosene spilled, NRW was unable to confirm what quantity entered the river, and could not comment on possible enforcement action while its investigation was under way and it gathered information.Public Health Wales advised that the community should avoid all contact with contaminated areas along the busy stretch of river, which runs parallel to many popular trails on both banks, including the Taff trail. People near the river had been complaining of sinus problems and headaches.“Kerosene vapours may be mildly irritating to the respiratory system.

Our current assessment is that people who can smell kerosene may experience temporary irritation, particularly if they are exposed for prolonged periods,” said the health body.Sarah Llywelyn, who lives in a riverside home in Glan Y Llyn downstream from the GE Aerospace facility, was among those who reported the leak to NRW.“The smell was absolutely unbelievable. My eyes burned as soon as I opened our door into the garden.

I knew it must have been huge because of the smell, and it’s a fast-flowing river – it was essentially unsafe from the point of contamination to Cardiff Bay. We moved here because of the river.

What I want more than anything is for lessons to be learned. This should never happen again.”A visit by the Guardian to the site found oily slicks still leaking into the River Taff five days after the incident began.

The NRW believes that the pollution has now been stopped from entering the river.An NRW spokesperson said: “Fuel that entered the drainage system before the leak was stopped by the operator could remain within parts of that network and whilst containment measures help reduce and capture pollution, they are not always able to separate all fuel from flowing water. Our work to investigate this incident and assess environmental impacts is ongoing.”Prof Steve Ormerod, from Cardiff University’s Water Research Institute, confirmed that the photos of the leaks appeared to show the kerosene still entering the waterway through the bunding (a secondary storage system, usually to catch overflows). “The Taff has been recovering from its grossly polluted past,” he said. “So this incident is a potential setback to clean water species such as salmon, dippers and kingfishers that have been recolonising the river.“Kerosene is a mixture of paraffins, naphthenes and benzene-like chemicals that risk direct toxicity to aquatic organisms, reductions in oxygen transfer across the water surface, and suffocation through impaired gill function in fishes or insects.

Effects on feather water-proofing are also likely in the birds that have no choice but to enter the water to feed. Overnight rain was insufficient to raise river levels and flush the Taff, so kerosene will still be lurking in backwaters and eddies along the river”.Gerwyn and Jordan Lewis from Ynysgau Farm, directly opposite the site of the main spill into the river, said they were advised by NRW that the river was unsafe for animals to drink from due to kerosene pollution, meaning that areas of the farm with access to the river could not be safely grazed.“We simply cannot take the chance of our animals becoming seriously ill or dying.

Our winter feed stocks could now be depleted at an alarming rate, leaving us facing the possibility of having to purchase substantial additional feed at considerable expense.“We also operate a tourism business comprising campsite pitches and glamping accommodation, a sauna and cold plunge facilities, all beside the affected river.”A GE Aerospace spokesperson said: “The safety of our employees, neighbours, and environment remains our top priority. We are continuing to work closely with Natural Resources Wales to address a fuel spill that occurred during repair work at our site on Friday 16 October.

The source was identified and isolated on Friday, and containment and clean up are ongoing, with specialist teams working both on and off site.”