Oren Case Study – May 2023

Refurbishing reed beds while maintaining compliance

Our client

Our?client?is a utility company.

The?location?is a rural village in England.

The?reed bed?– both measure 9m x 29m – and form part of a sewage treatment works.

Our situation

Our client had two reed beds used in the tertiary stage of sewage treatment, which needed a little love and attention, as they were not performing as well as they should. Overhanging trees surrounded them, and the reed beds had become blinded by organic matter with detritus was clogging the filter.

One of the reed beds was failing to do its job properly, but the other reed bed was partially working, so permits weren’t in breach.

The Oren Environmental team were asked to fully refurbish both reed beds to improve the performance of the two assets, extend their lifespan, and maintain compliance.

Our Approach

The surrounding trees and vegetation were cleared to allow light back into the site and reduce the number of leaves that littered the reed beds and roots. This was important as the weight of vegetation was becoming a structural issue for the retaining walls.

The sludge, organic matter, and gravel were removed from the layers of the reed bed, disposed of locally, and repurposed – a key driver for Oren Environmental. In fact, the surface sludge layer was taken to a local farmer for reuse within Land Spreading Agriculture S3 registration WEX360303.

Brand-new pipework replaced the original distribution and collection pipes. Additionally, the existing valves were cleaned, refurbished, and replaced.

The old reed bed liners were removed and replaced with HDPE geomembrane equivalents. New layers of gravel and stone were laid, and phragmites were planted.

Obstacles we overcame

Access

Narrow, weight-restricted roads throughout the village posed a problem. Access to the site is from a tight junction down a single-track road adjacent to residential houses. The reed beds are positioned at the bottom of a steep gradient, with limited vehicle access.

To overcome this, we created a temporary protective track – down a privately owned adjacent field – from the public highway to the project area. Additionally, this served to protect the main site’s access and operation.

The weather

The contrast in temperatures, from sun to snow, proved a challenge at times resulting in limited access to the site, which meant we had to be flexible and adapt our planned schedule of works.

Maintaining compliance

We were careful to ensure compliance levels were always maintained by collaborating with our client to develop solutions to mitigate risks. For example, alternating the closure of each reed bed while the other one was being worked on.

The central dividing wall

The organic matter made it impossible to assess the integrity of the retaining reed bed wall. We had to create a revised workaround to overcome this.

Our impact

As a result of our work, we’ve:

• Provided our client with two refurbished reed beds that will continue to be viable wastewater assets for many years if general maintenance is carried out
• Enabled the site to remain live and online throughout the project. As well as compliant in line with permitted discharge consent levels
• Helped our client to achieve their environmental goals by making sure waste was reused or recycled

Final word from our client

“Oren Environmental looked for alternative options and considered the impact on our customers – as well as providing safe access in and out of the site.

“This is the type of approach to scoping work, along with Oren Environmental’s experience with other projects of a similar nature, that provides confidence to the client that they have health and safety awareness and care for our customers.”

Project Engineer