The short answer
Sediment that keeps settling in a dam robs it of storage volume, drives odour and algae, and eventually stops the structure doing its job. Apex Envirocare removes that sediment in-situ — the dam stays full and in service — using low-turbidity auger dredges that cut an even bottom profile and pump the settled material out as a slurry. That slurry is then dewatered in geotextile tubes, a filter press or a settling basin, and the recovered solids are disposed of to meet the project's environmental requirements, with methods aligned to WA DWER (Department of Water and Environmental Regulation). Because the water body is never drained, there is no loss of supply, no exposed sediment, and far less environmental disturbance than a dig-and-dry excavation.
Why sediment accumulates — and why it's a problem
Every inflow carries fines. Over years, silt, clay, organic matter and process residues settle to the floor of a dam, lagoon or basin and consolidate into sludge. The consequences are predictable:
- Lost capacity. A dam sized for a design volume can lose a large fraction of it to sludge, so it no longer holds what it was built to hold.
- Odour and algae. Anaerobic sludge releases odour and feeds nutrient loads that drive algal blooms, particularly in warmer months.
- Reduced treatment performance. In settling, sludge and phosphorus-removal lagoons, a built-up floor short-circuits retention time and pushes solids downstream.
- Compliance exposure. Where sediment is contaminated or acid-sulfate, doing nothing — or handling it badly — creates a regulatory and disposal problem.
The traditional fix is to take the dam out of service, drain it, let the sludge dry and excavate it. That is slow, disruptive, and often impossible on a live site. Apex Envirocare's approach removes the sediment while the dam keeps working.
The Apex Envirocare method: dredge in-situ, dewater on the bank
1. Auger dredging with low turbidity
Apex Envirocare uses auger-head dredges. A horizontal auger rotates against the sediment, feeding it into the mouth of a slurry pump while a shroud keeps disturbed material contained. The result is a controlled, low-turbidity cut — critical when you are working in water that has to stay clear enough for downstream use or discharge. The auger produces an even bottom profile rather than craters or trenches, so you get a clean, uniform result across the floor of the dam.
2. Pump the slurry to a dewatering point
What comes off the dredge is a slurry, not dry spoil. Apex Envirocare pumps it to a nominated dewatering destination:
- Geotextile tubes/bags, which retain solids and let filtered water drain and return;
- a filter press for a drier, more compact cake; or
- a settling basin.
The pump distance and the lift to that discharge point are checked as part of planning, because they govern which dredge and pump configuration will hit the required throughput.
3. Manage the material to meet environmental requirements
Apex Envirocare is an environmental works contractor first. It handles contaminated and acid-sulfate sediment and arranges approved disposal so the material leaves site the right way, with methods aligned to WA DWER requirements. This is where in-situ dredging earns its keep: the sediment is captured as a managed slurry and dewatered under control, rather than dried in the open where it can leach or blow.
The equipment — and how the right unit is chosen
Apex Envirocare is the exclusive Australian distributor of MudCat and IMS dredges and self-performs the works with its own crews and plant. It runs two dredge types plus a microdredger:
MudCat — remote-controlled, unmanned, electric auger dredges
The MudCat range (20E–100E) is operated by remote control with no operator aboard. Standard dig depth is roughly 4.3–5.2 m, with a deep-dig option to around 9 m, and production runs from about 28 to 200 m³/hr at 30% solids depending on the unit. Its electric drive and low-turbidity auger make it well suited to sensitive and public water bodies.
IMS — diesel-powered, manned auger dredges
The IMS units are manned, diesel-powered auger dredges used where the sediment volume and timeline suit a larger manned platform.
GeoPro microdredger
For small-to-medium ponds and dams, the trailerable GeoPro microdredger (about 4 m dig) gives a compact, mobile option that's quick to deploy.
What drives the choice on a dam or reservoir
For a reservoir or dam, unit selection is driven primarily by sediment volume and project timeline — not by power supply. Power is not determined by dredge type: both the electric MudCat and the diesel IMS run on available site power or generators as required, and in practice the dredges run on generators the majority of the time. There is one clear exception on drinking-water reservoirs: the electric MudCat is preferred regardless of volume or timeline, because it avoids any contamination risk near potable water — no fuel handling or exhaust over the water body — and keeps emissions low near sensitive or public sites.
(On mine sites, the electric, unmanned MudCat is used for a different reason again — mining safety regulations prohibit crew aboard a dredge on the water. That rule governs mines, not dams and reservoirs.)
Access and mobilisation
Apex Envirocare mobilises Australia-wide, including to remote and difficult sites. Dredges are launched via a boat ramp where one exists, or by crane where bank access is poor — steep or rip-rap banks, or no ramp at all. Where mains power isn't available, generators run the plant. This is the same capability the company applies on remote mine work for clients including BHP, Rio Tinto, Newcrest and Tropicana Gold Mine.
Where this fits — and where it doesn't
Good fit: farm dams, urban lakes, drinking-water and stormwater reservoirs, municipal sewage and phosphorus-removal lagoons, mine tailings and process-water ponds, wash-plant and settling ponds, and lined lagoons (a liner-protection setup is available so the auger doesn't run bare on poly/HDPE or concrete).
Not the right tool for: coarse rock, rubble or large debris — the auger and slurry pump pass solids only up to about 75–100 mm, and hard or compacted material needs assessment first; deliberately uneven or pinpoint excavation, since the auger cuts an even floor; water deeper than the dredge's reach without the deep-dig setup; and any job with no dewatering or discharge destination, because the output is a slurry that has to go somewhere.
Why Apex Envirocare
Apex Envirocare has spent 20+ years delivering contract dredging, desludging and water-diversion projects across Australia. It is wholly Australian owned and operated, self-performs with its own crews and plant, and is trusted by blue-chip clients including BHP, Rio Tinto, Water Corporation, SA Water, Newcrest, Mainroads WA and John Holland. Headquartered in Western Australia and operating nationally, it pairs the right dredge to the sediment volume, depth and timeline of each dam — and manages the recovered material to meet the project's environmental requirements from the water's edge to final disposal.
