Pont-y-felin Lane

As a company, we depend on the environment for the water and wastewater services we provide. We take our responsibilities to protecting the environment seriously and we invest around £1 million a day in improving and maintaining our networks.

We also know that customers want us to do more, especially to help protect the quality of our rivers such as the Usk. This is why we’re planning to invest around £8 million to improve the way our CSO located in Pont-y-felin Lane, Torfaen, operates.

On this page you will find some information on the challenges we face and our proposals for improving the CSO, along with information about how you can share your feedback on our plans.

What’s the problem?

The quality of our main rivers is monitored by Natural Resources Wales. There is concern about the river water quality in parts of the Usk as they’re not achieving what’s called ‘good’ ecological status. This means that there are too many chemicals in the river such as ‘phosphorous’ which can cause algal blooms which can affect the amount of oxygen available in the water and harm wildlife.

There are several factors which can increase phosphate levels. This includes how we treat wastewater before it’s returned to the environment. Our modelling of the River Usk for example shows that our assets (i.e. our treatment works, Combined Storms Overflows or CSOs) are responsible for between 21% - 23% of the phosphates in the main water bodies, with CSOs only responsible for 1%. The remainder – over 75% - is caused by other factors such as agricultural run-off and animal faeces, urban surface water drainage, misconnected drains, as well as private septic tanks.

However, we understand that this is an important matter for communities, and we are committed to playing our part to doing what we can to reduce our impact on local rivers.

Pont-y-felin CSO

We have an underground CSO located on Pont-y-felin Lane which discharges into the Afon Lwyd. We are planning to invest around £8 million to upgrade this CSO using a nature-based solution which will help reduce the number of spills and boost the water quality in the Afon Lwyd and river Usk.

Developing solutions

We appointed Arup, a leading engineering consultancy, to explore the best options to help us achieve our goal of reducing the spills from the Combined Storm Overflow (CSO) to the local river water. They carried out a detailed study which assessed a range of options which are highlighted below.

Option Outcome
Optimising the existing system Upsize the existing pipework downstream of the CSO, which would increase the amount flow passed through the Eastern Valley Trunk Sewer before spilling at the CSO. Although this option would reduce the spills at this CSO, it was not considered feasible due to the current capacity within the sewer network. It also would not help us achieve the desired environmental outcome.
Flow removal Prevent storm water from getting into the network at the source (for example, disconnecting surface water pipes from the foul network, or laying new pipework to take surface water away). Our investigations showed that most of the surface water run off came from individual properties. Redirecting individual properties would cost a significant amount of money, generate a lot of disruption to our customers and would not achieve the desired environmental outcome.
Grey solutions Routing storm water overflows to a storage tank which would be put back into the network once the flows had reduced. This would involve building a 1300m3 storage tank next to the CSO which would be suitable for the space available. Our modelling showed that the storage tank would need to be approximately 20 times bigger to significantly reduce the number of spills. It would also not achieve the desired environmental outcome.
Nature based solution Treat storm water to a satisfactory quality using nature-based solutions before discharging it into the river. The use of reed beds and constructed wetlands are industry proven methods of treating waste water. This solution also provides an opportunity to enhance the space with green infrastructure for community use.

Our preferred solution

After assessing the different options, the nature-based solution was identified as the preferred solution in terms of the improving the river water quality, enhancing the local environment, and providing socio-environmental benefits to the local community.

This solution would involve creating:

  • Aerated reed beds, which would treat the storm water flows before they are released back into the environment.
  • Two wetlands, with a pontoon observation deck.
  • A compound, consisting of screening chambers to help remove any large particles such as rags and wet wipes, aeration blowers for the reed beds, a below ground overflow chamber and maintenance areas to serve each of these assets.
  • Access and maintenance tracks, which would allow maintenance vehicles to reach the assets as well as provide day-to-day use for pedestrians on foot.
  • Footpaths and walkways to allow pedestrian access between different entry points of the site.
  • Amenity infrastructure and educational areas, including seating areas and an outdoor classroom to allow the community to connect with the environment.
  • Biodiversity enhancements, such as insect hotels, bat boxes, tree planting and grassland seeding.

The benefits that this solution could bring include:

  • Improving the current landscaping
  • Creating sites to enhance biodiversity and ecology
  • Provide educational opportunities for people to learn about the environment
  • Reduce the risk of flooding to nearby properties
  • Retain the storm water flows before they reach the watercourse
  • Encourage the local community to spend more time outdoors
  • Improve current recreational facilities
  • Treat the wastewater currently spilling at the CSO which in turn will boost the local river water quality

Useful Information

AIA AMS - Treescene

785.8kB, PDF

Arboricultural Impact Assessment - Treescene

3.5MB, PDF

Flood Consequence Assessment

3.9MB, PDF

Site Location Plan

350.8kB, PDF

Compound Layout

1.9MB, PDF

Compound Elevations


Site Drainage

2.1MB, PDF

Landscape Section A-A

15.6MB, PDF

Existing Site Layout

435.8kB, PDF

Issue Register

198.5kB, PDF

Water Environment Regulations Compliance Assessment

4.3MB, PDF

Habitats Regulation Assessment (HRA)

10.6MB, PDF

Ecological Impacts Assessment (EcIA)

8.4MB, PDF

Odour Assessment

2.3MB, PDF

Tree Protection Plan - Treescene

3.4MB, PDF

Tree Survey - Treescene

771.1kB, PDF

Application for Planning Permission

180.1kB, PDF