The situation
Oren Environmental operates and maintains many water treatment schemes across the UK for customers, manages reed beds, and undertakes large-scale desludging projects for various commercial organisations.
As industry leaders in our sector, our customer asked us to desludge two settlement lagoons at their water treatment scheme.
The two settlement lagoons are part of the treatment process that removes harmful deposits from the water, preventing them from polluting nearby watercourses and harming ecosystems.
Over time, settlement lagoons can get choked with vegetation. Additionally, heavy deposits in the water drop to the bottom of the settlement lagoon as part of the treatment design. These solids combine and, over time, reduce the capacity of the available treatment area. What’s more, with the same amount of water travelling at velocity through a smaller space within the settlement lagoon, solids get carried over to the neighbouring reed bed, which causes it to become blinded.
This is why settlement lagoons need to be regularly cleaned and maintained. Our customer recognises this and appreciates that continual maintenance keeps treatment processes running optimally and prevents watercourse pollution.
Our approach
We removed the top water from the two settlement lagoons and stored it in tankers so we could reuse it for jetting. This honours our commitment to sustainability by recycling water whenever possible.
Large amounts of sludge were decanted from the settlement lagoons into a newly refurbished sludge drying bed. This dewatering technique removes water content from the sludge, making it easier to transport in fewer trips. This sustainable approach is also more cost-effective for our customer.
One of the settlement lagoons had significant quantities of vegetation that had to be excavated using suction to avoid further damage to the liner—again, keeping costs down for our client. Vegetation below the settlement pond had burst through the baseliner, which was patched and repaired.
Obstacles we overcame
- Sludge volume and thickness – the design of the settlement lagoon was intended to allow auto desludging via valve operation. However, due to the density of the sludge, it needed a little encouragement. We achieved this by reintroducing the surface water retained in the tankers and/or opening valves to allow a small amount of pumped water back into the lagoon to aid the waste suspension, enabling the sludge to flow more freely.
- Maintaining compliance: Throughout the process, we monitored and collected samples from the discharge points using on-site testing equipment and lab-supported processes to satisfy environmental consent to discharge
Our impact
As a result of our work:
- Our customer now has two settlement lagoons free from excess sludge and vegetation, which allows them to hold more water and retain it for longer, improving the treatment process.
- The sludge-drying bed we constructed and installed now dewaters sludge, making it easier and cheaper to transport and recycle.
- The sludge is reused as spread for farmland. This happens after it’s dried out and deemed stackable for transportation.
- The nearby watercourses will remain protected from water pollution in the future.
Works were delivered on time and to budget, as per our customer’s expectations.
