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More details from Piers….
ST DOGMAELS/CARDIGAN ODOUR UPDATE
We were thrown off the scent, so to speak, because the terrible pong fitted with our impression of what bad sewage should smell like. And it seemed to be coming from the river. The smell of muck spread on a field is, in our minds, a very different , more animal smell. We were wrong. The smell is almost definitely coming from badly managed farm slurry.
I’ve been looking into it and it is almost certainly Hydrogen Sulphide, H2S, the classic rotten eggs smell. It occurs at low levels in cattle manure but certain bedding materials and feed will increase the level. Someone asked about methane, but that is an odourless gas.
Because Hydrogen Sulphide is heavier than air it will sink from the farms and into the valleys onto the rivers. The smell then seems to be coming from the river. This has caused some confusion and explains why Dwr Cymru were unable to find any of their assets malfunctioning.
There are a number of issues that can cause elevated Hydrogen Sulphide levels in slurry. Possibly the main one is poor mixing/stirring practise in the slurry tanks. You can read up on this at https://www.nidirect.gov.uk/news/stay-safe-when-mixing-slurry if you wish to know more.
Also things like:
1. Gysum Bedding (often reclaimed from waste plasterboard). Highly absorbent and ‘drying agent’ in slurry management.
hse.gov.uk :
“There is clear evidence that the presence of gypsum in slurry will enhance the potential for generation of toxic H2S gas. The levels of the gas produced, even from the small, contained systems, would be toxic to anyone exposed to equivalent concentrations on a larger scale. Therefore, if gypsum residues enter slurry this could increase the risk of H2S gas accumulation in confined spaces in the close vicinity of slurry systems. It is important therefore that this is taken into account in managing risk.”
1. Distillers grain diet.
Distillers grain diet:
Cattle fed wet distiller’s grain had higher fecal and urinary sulfur excretions than control cattle not fed distiller’s grains (Spiehs and Varel, 2009). Although these authors did not measure hydrogen sulfide in their study, they conclude that it is likely that increased hydrogen sulfide would result from cattle being fed wet distiller’s grain.
There may be other elements in the management of cattle which are causing these H2S releases, but without talking to the farmers, we won’t be able to find out. Insufficient
Hydrogen Sulphide is an extremely toxic gas, and even at low levels can cause respiratory difficulties and skin reactions.
“At low concentrations (less than 1 ppm), hydrogen sulfide is an irritant with the odor of rotten eggs. At higher concentrations, however, it deadens the sense of smell, often immediately, making detection difficult (Donham et al., 2006; Doss, Person and McLeod, 2002; Hooser et al., 2000). Abrupt exposure to amounts of greater than 500 ppm of hydrogen sulfide has killed humans; exposure to 200 ppm of hydrogen sulfide has killed swine. Extended exposure to lower amounts of hydrogen sulfide has also resulted in a range of symptoms from eye irrita- tion to respiratory illness to uncon- sciousness (Donham et al., 2006;”
Anecdotal evidence on a recent Facebook thread about the smell, included villagers saying they could both smell and taste the Hydrogen Sulphide. This suggests the release is above safe levels.
It would be interesting to get readings done ‘at source’. If it can be smelt throughout such a wide area, it’s possible that ‘at source’ there is a high concentration, which may well be hazardous to workers on that site.
We might get quite low readings away from the source and be told that it is not hazardous to humans. The question then is whether a local community is willing to put with this degree of pollution in an area known for the good quality of its air.
A bright and helpful person NRW rang me in response to my ‘incident log’ about the odour in St Dogmaels recently. She said they are aware of the situation but that anything odour based is a County Council issue and not one they are empowered to investigate. She pointed out that in order to the the CC to act we need to get as many people as possible to log their complaint (with time and location). I will chase this up unless anyone else already has done so, or is planning to.
As milk prices fall, the only way farmers can maintain income is to increase herds sizes and milk production so they are cramming more cattle into their winter sheds. Many cattle spend their entire lives in these sheds and are fed a cocktail of additives to maximise their yield and keep vets bills to a minimum. Managing the waste from these oversized herds with limited available agricultural land means that slurry tanks fill faster and need to be emptied more frequently. Quite a lot of farmers are pumping direct from the tanks onto the same available land. The good old days of grass fed, spillage fed cows producing a not unpleasant slurry smell are over, and instead we have shed farmed cattle producing a slurry that smells industrial.
Piers
Bear in mind that we tested the water coming out of the sewage pipe, not the river water. There is a lot of info available, and can be quite confusing:
This is a NRW report – https://naturalresourceswales.gov.uk/about-us/news/news/tighter-phosphate-targets-change-our-view-of-the-state-of-welsh-rivers/?lang=en
UK Government guidance recommends that rivers should not exceed annual mean phosphate concentrations of 0.1mg per litre. https://view.officeapps.live.com/op/view.aspx?src=https%3A%2F%2Fassets.publishing.service.gov.uk%2Fgovernment%2Fuploads%2Fsystem%2Fuploads%2Fattachment_data%2Ffile%2F1126652%2FPhosphorus-challenges-for-the-water-environment.odt&wdOrigin=BROWSELINK
The UK drinking water standard requires the nitrate concentration to be less than 50 parts per million. https://thewaterprofessor.com/blogs/articles/nitrate-in-drinking-water#:~:text=The%20UK%20drinking%20water%20standard%20requires%20the%20nitrate,common%20problem%20for%20private%20water%20supplies%20%28water%20wells%29. NRW has much ino too: https://naturalresources.wales/about-us/what-we-do/water/nitrate-vulnerable-zones/?lang=en
In the US recommendations officially state the limit for nitrates at 10 mg/L. Nitrates in Water? Safe Levels and How to Remove it – Pick: Comfort
Hope that helps
In early October 2022 Adam and I used some testing kits to check the levels of Phosphates and Nitrates coming from the Sewage outflow pipe into the Teifi from the outflow pipe below Cilgerran Castle at the confluence with the Plysgog.
Here are the results we obtained: For Nitrates
and for Phosphates:
It appears that not all that stinks in a river is sewage! This is such useful information I have reproduced it here…
In response to a fb post in ‘St Dogmaels Positive People Posts’ on 22-Dec-22 which was follows:
“My most positive hope for the New Year is that sulphurous PONG that hangs over the village and Cardigan again today gets identified and dealt with before more harm is done. If you have any clues, message me, please.
Piers Partridge replied …
“In reply to St Dogmaels Local Producers’ Market, I’ve been looking in to this and, Yes, it’s a distinctly gassy smell, but probably not methane which is odourless. We’ve been getting this smell when there have been no sewage releases so it is also probably not sewage. Most likely it’s Hydrogen Sulphide, which has the classic rotten egg smell, and is coming from agricultural slurry, or waste. The gas is heavier than air so will travel downhill and settle on the river bed. People then think the river is the source of the smell, which confuses the issue. My reading suggests that there are certain modern bedding additives and food supplements given to cattle which change the chemical makeup of slurry and if not managed properly can create the release of Hydrogen Sulphide.
It’s not harmful to human health if you can simply smell it, but being able to ‘taste’ it, as some people have reported suggests it is above safe levels. Please message me if you experience that or any other information you might have.”
Many thanks to Piers for his research into this.
I thought I would add an edited version of Nathaniels further thoughts here…
“Well done for reporting and noticing the incident Dave. While it is awful to see this, it re-emphasized why we began setting up adopt groups in the first instance, your eyes & ears on the ground are indispensable and without this it would/could have gone unnoticed. Spreading this sort of information could lead to community pressure to change behaviour and is what I feel these groups have the ability to instil. However, we must approach it in an open way that does not isolate or provoke the offender in the first instance.
I looked up the sewage hours for outfalls in the Cilgerran area, on average they spill for 11-12 hours at a time. I could be wrong in my assumption of slurry, but given the colour that was my assumption, it was something we were worried about when we saw the number of spreaders out before & during the cold weather. You can find the hours & locations here. https://theriverstrust.org/sewage-map
If there is another incident, a group alert and visual check of the river in your locality, followed by as many as possible reporting the incident is my suggested approach.
Best wishes,
Nathaniel
Project Officer
West Wales Rivers Trust
Phone: 07780303533
Email: nathaniel@westwalesriverstrust.org
Website: http://www.westwalesriverstrust.org “Last Saturday the 17 December I walked down the Teifi to the confluence with the Plysgog and was shocked by the state of the water coming down. I really had no idea what was the cause. CSO event and broken septic tank crossed my mind as there was a very strong sewage like smell. But it wasn’t until I sent photos and video to Nathaniel and got his reply that things became clear. His reply was….
“Oh no! That to me looks like slurry – be it a failure or runoff. Sewage would be milkier as would a septic tank. By the speed & rate of bubbles accumulating I’d imagine very high in nutrients and oxygen demand.
Was anyone else able to see the river further upstream on this date?
It could be that, as I saw on a couple of tributaries round Wales in the last fortnight farmers were applying liquid and / or solid muck on their fields during the dry spell, only this was followed by an unexpected cold snap, some snow / sleet and then a sudden melting. Therefore what had been applied froze before it could “soak in” then had a sudden unexpected thawing out followed by intense rain. I would hope this is the case and doesn’t repeat.
Log the suspected incident with NRW if possible 0300 065 3000 request an incident number while on the phone and email them images and video, asking to be informed of environment officers thoughts, perhaps let them know of the group at the same time. I understand it’s late, but it’s good for them to have these logged should anything else in the catchment happen or been reported.”
I did report the incident to NRW – log number is 2208914
Image of the Pollution entering the Teifi:
Foam like a bubble bath on Plysgog just upstream of confluence…
Here is a link passed onto us by Nathaniel on how to recognise brown trout spawning areas called “Redds”…
We had our first outing on Sunday the 27th November lead by Nathaniel of the Teifi Restoration Project. A most enjoyable four hours of exploration and discovery along the Plysgog. Nathaniel is a mine of information and spreads his knowledge freely. We used the App to report 15 issues ranging across: Artificial Barriers, Natural Barriers, Water quality issues, Habitat issues and Invasive species. Many many thanks to Nathaniel for his time and input.
