Remote-controlled dredging cuts costs at Christchurch ReadyMix

Sand extraction costs matter in the ready-mix concrete business. When Christchurch ReadyMix Concrete was looking to reduce their high extraction costs and improve operational safety, they turned to modern dredging technology for a solution.

The challenge

Christchurch ReadyMix were looking to improve the efficiency of their sand extraction operation. Traditional methods came with higher extraction costs and required managing health and safety risks, particularly with the material discharge point located 700 metres from the dredging operation. Using a dredge provided an opportunity to reduce both costs and risk while streamlining the overall process.

For quarry operations in New Zealand, three main extraction methods are commonly used. The first is suction dredging, which involves floating a surface-mounted pump on a pontoon and extending a hose down to the product surface. This method is limited by suction lift requirements and can be fuel-inefficient. The second is excavation using a digger and dump trucks, requiring multiple machines working in rotation, which increases both labour and equipment costs. The third option is a digger-mounted submersible dredge pump, which moves down into the material itself rather than trying to pull it up from the surface, offering greater efficiency in certain conditions.

The solution: Dragflow DRP120

Prime Fluid Management recommended the Dragflow DRP120 because it directly tackles the main operational challenges on sites like Christchurch ReadyMix. The DRP120 is a compact pontoon that houses a submersible dredge pump, which is winched precisely into position on the quarry floor. Operators can control the unit remotely from up to 700m away, allowing staff to manage the entire dredging process from the safety and comfort of the office.

This configuration keeps personnel out of potentially hazardous areas and ensures close oversight of extraction activities. Its modular pontoon design allows it to work in tighter or shallow spaces where larger equipment isn’t practical. Real-time monitoring through remote sensors also means adjustments can be made quickly, keeping things efficient and safe. The end result is a practical, low-risk way to get effective material recovery from challenging sites.

Get all the details on Dragflow’s dredging solutions by downloading the Dragflow Dredges brochure.

The results

Dredge operator Simon Gill said that the DRP120 extracted sand faster than their previous method of using a digger to fill two dump trucks. The single-person operation of the DRP120 outperformed the traditional multi-machine approach while cutting costs.

"The DRP120 extracts sand quicker than a digger filling two dump trucks. Buying the dredge was a great idea," Gill stated.

The dredge successfully addressed Christchurch ReadyMix's key challenges: reducing extraction costs while improving safety by allowing remote operation away from the extraction site.

Why remote-controlled dredging works

The success at Christchurch ReadyMix highlights several advantages that remote-controlled dredging brings to quarry operations. Beyond the obvious safety benefits of keeping operators away from extraction sites, the technology addresses several practical challenges that quarry managers face daily.

Remote operation eliminates the need for personnel to travel between the control point and extraction site, particularly valuable when dealing with distances like the 700 metres at Christchurch ReadyMix. This reduces both travel time and the safety risks associated with moving around active quarry sites.

A key advantage is the single-operator requirement, which represents a significant reduction in labour costs compared to traditional excavation methods. Conventional setups often require a digger operator supported by multiple trucks ferrying product from the extraction point - typically operating in sequence, with one loading while another transports material away. Remote-controlled dredging simplifies this process, reducing both equipment and personnel requirements. This labour efficiency becomes even more valuable when skilled operators are difficult to find and retain.

Choosing the right approach

Different quarry situations call for different dredging approaches:

• Site accessibility and layout - Remote-controlled systems work well when discharge points are distant from extraction areas or when site access is challenging.
• Material type and volume - Submersible dredge pumps handle varying sediment densities more effectively than surface-mounted systems.
• Fuel economy efficiency needs - Submersible dredge pumps pump technology typically consumes significantly less fuel than cutter suction dredging methods.
• Operational safety requirements - Autonomous and remote-controlled systems reduce personnel exposure to hazardous work areas.
• Environmental considerations - Modern dredging creates less sediment disturbance compared to traditional excavation methods. 

Small quarry operations often find mini dredges sufficient for their needs, while larger sites may require more substantial equipment. The dredge category offers flexibility for operators who need to move equipment between different extraction sites. Dragflow supplies a range of dredge types and sizes to suit different extraction environments, from compact mini dredges through to autonomous and cable dredges designed for operations where extraction depth and volume are significant.

For Christchurch ReadyMix, remote-controlled dredging proved an effective solution for their operational needs. If your extraction costs are increasing or you're managing ongoing safety risks around material handling, it may be worth reassessing whether your current methods are still the right fit for your operation.

To discuss dredging solutions for your operation, get in touch with our team.