We are pleased to report that this week Natural Resource Wales has issued Dwr Cymru a permit variation for the Bronaber treatment works. This now includes a Total Phosphorus limit of 5mg/l effective from the 24/06 and for the limit to be reduced further to 0.8mg/l from 31/03/2030. Previously the Bronaber sewage works had no limit imposed for Total Phosphorous.

'Total phosphorus" on a permit from a sewage works refers to the total amount of phosphorus present in the effluent discharged from the sewage treatment plant. Phosphorus is a nutrient that is commonly found in sewage due to human waste and detergents. It originates from several sources within the sewage treatment process:

Human Waste: Phosphorus is naturally found in human waste products, such as urine and faeces.
Detergents: Many detergents contain phosphorus compounds which are washed down drains and end up in sewage systems.
Industrial Effluents: Industrial processes may also contribute phosphorus to sewage systems depending on the nature of the industries discharging into the sewage system.

Total phosphorus is a concern for rivers and other receiving water bodies for several reasons:

Eutrophication: Phosphorus is a nutrient essential for plant growth. When excess phosphorus enters rivers and lakes (often due to sewage discharge), it can lead to over-fertilisation of aquatic plants and algae. This excessive growth can disrupt the balance of the aquatic ecosystem, leading to algal blooms and reduced oxygen levels (hypoxia) as the algae decay. We have seen this evident for many years at this site. So this decisions is a welcome addition to the permit.
Water Quality: High levels of phosphorus can degrade water quality, making it unsuitable for drinking, recreation, and supporting diverse aquatic life.

The permit has also reduced the Suspended solids to 60 mg/l LUT, the BOD limit will reduce to 40 mg/l LUT from 01/01/2025. The Ammonia limit will reduce to 20mg/l LUT effective from 31/03/2030 included under AMP8 NEP.

After analysing the treatment facilities and the estimated population figures they are based on, we became concerned that these might not accurately reflect the actual numbers from the holiday village. Dwr Cymru stated that they base the calculation on an estimated population of 421. However the Alpine holiday village alone has approximately 400 lodges/ apartments and buildings connected to the Wwtw let alone the houses in the village. Many people stay at the holiday village for 11 months of the year. We estimate it is more likely to be 1000 people minimum.

The Afon Eden is a Special Area of Conservation and a Site of Special Scientific Interest, home to endangered species facing extinction. Areas like the Afon Eden require the highest levels of protection, which is why we welcome these new restrictions.

Data Concerns

On 23rd May, we submitted a data request to both Dŵr Cymru and NRW for identical information, including: all 15-minute flow to treatment and final effluent flow data (preferably MCERTS-certified); total daily volume (TDV) data as submitted to NRW; individual spill start/stop times recorded by all EDM devices since installation; any noted issues, non-compliance data, actions taken, incidents, maintenance problems, and complaints. We also sought clarification on how permit levels were determined, including the factors and population estimates used at the time of issuance, alongside the number of residents these calculations were based on.

We received data from both NRW and Dŵr Cymru this week.

Although we requested all recorded data from Dŵr Cymru, they only provided spill data from 2019. However, NRW supplied data dating back to 2011.

NRW's data indicated that between 2011 and 2023, Dŵr Cymru had 903 missing entries, spanning the years 2011 to 2022.

Maintenance Issues

NRW did not provide a list of known maintenance issues as they did not possess this information. Dwr Cymru supplied a basic list detailing the year, category, and whether the work was planned or reactive. "Reactive" indicates instances of emergency bursts or breaks.

We observed that 72 issues were classified as "reactive," suggesting irregular maintenance with responses triggered by emergency failures at the works. 101 interventions were pre planned interventions at the works.

Our initial interest in the works stemmed from consistently high nutrient levels in the river, aggressive plant growth, low oxygen levels, and algae on potential spawning gravels. Subsequently, we discovered sewage fungus near a tributary and discharge pipe. Upon speaking with the landowner, they mentioned issues at the works and a significant number of lamb losses this year, prompting us to investigate further.

Upon closer inspection at the works, we identified a point source spring emitting E. coli that NRW confirmed as 55,000 units per 100ml. This "spring" leak was located along the perimeter fence line within 0.5 cm of the sewage works fence. A desk-based analysis revealed a 2017 consultancy report that noted a pipe leaking effluent in the same area. However, during a site visit on June 3rd, Dwr Cymru stated there had never been a pipe leak and attributed the 2017 issue to a broken tank, which according to the data, was broken and fixed in 2016. Thus, the leak must be another issue listed in the report, with only one noted instance being a retrofit pipe in 2018.

The data therefore does not correlate with the site visit information we received on the ground from Dwr Cymru staff.

Image from the maintenance list at the works

After publishing our E. coli results on social media, we noticed each evening for three weeks that the filtration tank remained stationary and unchanged. We promptly reached out to Dŵr Cymru via multiple emails to inquire about this issue, noting that the decrease in spring pressure seemed connected. Despite our efforts, we did not receive a direct response regarding this concern.

During a scheduled site visit on June 7th, the Process Operator asserted that our observation was mistaken, claiming the filtration tank had never been turned off or obstructed from turning. This assertion contradicted our recorded video and photographic evidence. Later that day, a Dŵr Cymru staff member informed the landowner that a broom had been wedged against the tank's filter arm, causing it to cease turning.

In light of these conflicting accounts, we requested Dŵr Cymru to clarify the situation in writing. Their subsequent response stated:

"The Process Operator confirmed that the filter arm was obstructed and unable to turn overnight on the evening of June 6th (approximately 10-12 hours). This incident had minimal impact on site operations, only slightly elevating ammonia levels in the final effluent, which remained well within permitted limits. Importantly, there were no losses or leaks from the filter throughout this period."

This contradicts our own observations from 17th May to 7th June and also conflicts with the information we were initially given on 7th June.

Upon our request to conduct tests at the treatment works, a collapsed pipe was discovered above the facility. The localised leak we identified, with 55,000 parts of E. coli per 100ml, was dismissed as naturally occurring and clean. We insisted on further testing with Dŵr Cymru, who reported a recent finding of 10,000 parts of faecal matter per 100ml. Despite the proximity to the sewage works and the identified point source, Dŵr Cymru attributes this contamination to agricultural sources.

We dispute this assessment based on the specific point source, its proximity to the old sludge beds, and the fact that the landowner maintains 17 cattle on a 4km site. We strongly disagree. On 17th June, Dŵr Cymru excavated an area on site where we believe the contamination originated within the property boundaries. Dŵr Cymru reported finding no infrastructure there. Images are provided below. Further details can be found in our initial report. Dŵr Cymru asserts that the elevated E. coli levels are not originating from their facility. We will request NRW to investigate the cause of such high levels at this specific point source.

Given the data and the context, it's reasonable to consider that both the historical activities of the sewage works could play a role in the contamination. However, without further specific information or testing, it may be challenging to definitively attribute the high E. coli levels solely to one source over the other.

To resolve this issue conclusively, additional comprehensive testing and investigation would likely be necessary using expensive DNA methods, including analysis of the discharge composition, detailed mapping of the sewage works infrastructure (which Dwr Cymru say they do not hold) , and potentially microbial source tracking to identify the origin of the contamination accurately.

NRW has also confirmed that the works is currently under enforcement action for non-compliance in 2020 and missing data. They can not comment on this further until the investigation is complete.

North Wales Rivers Trust will continue to monitor the works, the Eden, and its tributaries to promptly detect any significant changes. Additionally, we have lodged a formal complaint with NRW regarding its hotline incident reporting process. We met with NRW staff on Tuesday to discuss our concerns, and they are conducting an internal review of the process.

Despite what has felt like a frustrating process we are pleased that the 10m collapsed pipe further upstream has been identified and fixed and that the works has been given tighter permits. This will benefit the river and give its most endangered species a fighting chance. We will keep our stakeholders updated on the progress of the Freshwater Pearl Mussel project with ongoing information.

Bronaber WwTW - Process Units and Stages of Treatment.

Bronaber WwTW is a biological filter site currently serving a population of approximately 421. Effluent arrives at the WwTW by gravity. At the inlet there is a screen for storm overflow. Normal crude flows pass through the inlet and are pumped up to 2 above ground container Primary Settlement Tanks (PSTs).

Settled sewage then gravitates to the single granite media biological trickling filter with a paddle wheel drive.The filtered effluent then gravitates to two horizontal Humus Settlement Tanks (HSTs).

Treated effluent discharges to the sample chamber and outfall into the Afon Eden. Sludge removed from the Humus Settlement Tanks are pumped to the top of the works for co-settlement in the Primary Settlement Tanks. Humus desludge pump can also be utilised for recirc in low flows.

A sample of the listed missing data entries.