Pond Sludge Surveying
While using pond systems for municipal wastewater treatment is generally low-maintenance, one of the disadvantages is inevitable sludge build-up. The question isn’t if you’ll need to desludge - it’s when.
BPO provides highly accurate sludge surveys so you can plan removal at the right time, protect treatment performance and manage budgets with confidence.
Our work is based on data, not opinions.
Understanding what’s happening beneath the surface.
Pond systems are commonly used for municipal wastewater treatment across New Zealand, particularly in smaller communities. Because they require minimal day-to-day oversight, sludge accumulation can often go unnoticed for long periods.
Desludging is an impactful, but infrequent cost. Mobilisation, dredging and dewatering require substantial setup, so delaying removal can appear financially attractive.
But, excessive sludge accumulation can:
Reduce effective treatment volume
Cause hydraulic short-circuiting
Impact effluent quality
Increase compliance risk
Accurate sludge measurement allows operators to balance operational efficiency with financial responsibility.
When you know precisely where sludge is accumulating and how much is present, you can plan removal strategically - not reactively.
BPO’s survey approach
BPO uses sonar and GPS technology to map water beds, measuring sludge thickness and volume in the basin. A remote-controlled vessel surveys the pond surface, recording:
Geographic position using GPS (±1 metre accuracy)
Sludge layer depth using sonar (±0.05m accuracy)
Approximately 4,000 data points per hectare
Minimum depth detection of 0.3 metres
This data is then used to produce a 3D image of the basin, showing sludge volume, location and depth.
Further analysis can determine the effect of sludge build-up on treatment efficiency and likely location of short-circuiting.
Why sludge surveys matter
A BPO sludge survey provides:
Accurate mapping of sludge accumulation
Assessment and risk of high-accumulation zones
Identification of short-circuiting paths
Improved safety compared to manual methods
Improved accuracy with over 4,000 data points per hectare
Independent assessment - no conflict of interest around dredging decisions
Armed with accurate sludge data, operators can plan sludge removal precisely and economically.
If you need clarity before committing to desludging, have a chat with us.
We are a 100% Kiwi-owned wastewater treatment business with decades of experience behind us. We value a human approach, the team you talk to, is the team on the ground. Pinpoint accuracy, everyday compliance and a future focused approach - our superpower? We can spot a problem before it is a problem.
Projects
Keen to see our work? Check out our latest projects.
