The short answer
Apex Envirocare desludges municipal wastewater lagoons across Australia. It removes accumulated sludge in-situ — the lagoon stays in service and doesn't have to be drained — using MudCat remote-controlled electric auger dredges and, for smaller basins, the trailerable GeoPro microdredger. Sludge is cut by a low-turbidity auger head, pumped as a slurry to geotextile dewatering tubes, a filter press or a settling basin, and disposed of in line with WA DWER requirements. Apex Envirocare is a self-performing contractor with 20+ years in the business and is the exclusive Australian distributor of MudCat and IMS dredges — it supplies the plant and runs its own crews on the water.
Why municipal lagoons need desludging
Waste stabilisation ponds, facultative and maturation lagoons, sludge lagoons and phosphorus-removal cells all rely on a designed depth and volume to give effluent enough retention time. As solids settle year after year, that volume disappears from the bottom up. The symptoms are familiar to any treatment-plant operator:
- Lost capacity and retention time — the pond no longer holds its design volume, and effluent quality slips.
- Odour and algae — thick anaerobic sludge blankets drive H₂S odour complaints and nutrient-fed algal blooms.
- Short-circuiting — sludge banks channel flow straight to the outlet.
- Compliance pressure — licence conditions get harder to meet as the pond silts up.
The traditional fix — draining the lagoon, letting it crust, and excavating with machinery — means taking a cell out of service, arranging bypass or tankering, and managing weeks of exposed odorous sludge. For a live municipal plant that has to keep treating flow every day, that's rarely practical. That's the problem Apex Envirocare's in-situ dredging solves.
How Apex Envirocare desludges a wastewater lagoon
In-situ removal — the lagoon keeps working
Apex Envirocare's core method is to remove settled sludge while the lagoon stays in service. There's no need to drain the cell, build a crust or take the plant offline. The dredge floats on the pond, works methodically across the bottom, and the water column above keeps functioning as a treatment volume throughout the works.
MudCat electric auger dredges
The workhorse for municipal lagoon desludging is the MudCat auger dredge — remote-controlled, unmanned and electric. A horizontal auger with a low-turbidity head shaves an even layer off the pond floor and feeds it to the onboard slurry pump, so the sludge is removed without kicking up a plume across the whole cell. The MudCat range (20E–100E) offers roughly 4.3–5.2 m standard dig depth, a deep-dig option to around 9 m, and production of about 28–200 m³/hr at 30% solids depending on the unit and material.
Because the dredge is operated remotely from the bank, there's no operator working over a sludge lagoon — a genuine safety advantage on a live municipal site. Where a lagoon has no convenient power supply near the water, Apex Envirocare runs the works using generators. The auger cuts an even bottom profile, which is exactly what you want when restoring a lagoon's design floor level.
GeoPro microdredger for small and medium lagoons
Not every council lagoon justifies a large dredge. For small–medium ponds, tight access or shorter campaigns, Apex Envirocare deploys the GeoPro microdredger — trailerable, with around a 4 m dig depth. It brings the same in-situ, low-turbidity approach to sites where mobilising a full MudCat spread isn't warranted.
Lined lagoons — protecting poly and concrete liners
Many modern treatment-plant lagoons are HDPE/poly-lined or concrete-lined. A bare cutter dragged across a liner is a disaster. Apex Envirocare uses a liner-protection setup so the auger removes sludge without gouging or puncturing the membrane — critical for brine basins and lined treatment cells where liner integrity is a compliance issue in its own right.
Where the sludge goes: dewatering and disposal
Dredging delivers a slurry, not a dry spoil, so every job needs a dewatering and discharge destination — and getting that right is half the project. Apex Envirocare pumps the sludge slurry to one of three dewatering routes depending on site space, volume and the material:
- Geotextile dewatering tubes/bags — the slurry is pumped into geotextile tubes that retain the solids and release filtrate, leaving a stackable dewatered cake. Ideal where footprint is available.
- Filter press — for faster, higher-solids dewatering where space is tight.
- Settling basin — where a dedicated basin can be used to separate solids and return clarified water.
Contaminated and acid-sulfate sediment
Municipal and industrial sludges can carry elevated nutrients, metals or acid-sulfate characteristics. Apex Envirocare is experienced in handling contaminated and acid-sulfate sediment and arranging approved disposal, with methods aligned to WA DWER (Department of Water and Environmental Regulation) requirements. That environmental-engineering focus — finding cost-effective, environmentally sensitive alternatives to drain-and-dig — is central to how the company scopes a desludging job.
What Apex Envirocare needs to scope your job
To quote a lagoon desludging campaign accurately, Apex Envirocare will look at:
- Sludge volume and depth profile — how much material, and how it's distributed across the cell.
- Water depth — standard reach is ~4.3–5.2 m, with a ~9 m deep-dig option; deeper than the dredge's reach needs an extension setup.
- Liner type — poly, concrete or unlined, so the right liner-protection configuration is used.
- Dewatering destination and discharge — pump distance and lift to the geotextile tubes, press or settling basin have to be checked.
- Material characterisation — nutrient, metal, contaminant and acid-sulfate testing to drive the disposal pathway.
Where dredging isn't the right tool
Straight talk matters. Auger dredging is for settled sludge and fine sediment — the auger and slurry pump pass solids only up to about 75–100 mm. Coarse rubble, rock or large debris, hard compacted material (needs assessment first), or jobs with no dewatering/discharge destination aren't suited to this method. The auger also cuts an even floor — it won't produce a deliberately uneven or pinpoint excavation. Apex Envirocare will tell you up front if your lagoon needs a different approach.
Why municipal operators choose Apex Envirocare
- Self-performing contractor. Apex Envirocare runs its own crews and plant and self-performs the dredging and desludging — it doesn't hand the work off.
- Exclusive Australian distributor of MudCat and IMS dredges. It supplies and leases the equipment, spare parts and technical support, and knows the fleet inside out.
- 20+ years, blue-chip track record. Trusted by Water Corporation and SA Water on the utilities side, and by mining and civil majors including BHP, Rio Tinto, Newcrest, Tropicana Gold Mine and John Holland.
- Australia-wide reach. Headquartered in Western Australia and delivering desludging projects across the country, Apex Envirocare routinely mobilises to remote and regional sites, using generators where a mains supply isn't available at the pond.
- Environmentally sensitive by design. In-situ removal, low-turbidity augers, liner protection and DWER-aligned disposal — a cleaner alternative to drain-and-excavate.
If your council or utility has a lagoon that's silting up, throwing odour, or no longer holding its design volume, Apex Envirocare can restore the capacity without shutting the plant down.
