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Introduction: The Complete Guide To Quarry Water Management and Pumps
Quarrying for stone, minerals, gravel, and raw materials is an important industry in the UK. Every year, quarries around the country support the building of 180,000 homes, the maintenance of the country’s 230,000-mile road and 10,000-mile rail networks, an ambitious and ongoing hospital building programme, and continuing school and university improvement projects.
The quarrying industry employs around 20,000 people directly and a similar number indirectly, not to mention the large number of suppliers, contractors, and service companies that support businesses directly involved in quarrying. At the time of writing, in 2021, there are around 1,300 active quarries in the UK contributing £3 billion to the economy every year.
This guide introduces how water is used and managed in quarries and the equipment required for an efficient water management system.
Quarrying and the Environment
Effective water management is important both to maximise efficiency and productivity on site, and to avoid the potential environmental damage that comes from mineral extraction.
Modern quarrying methods and equipment are generally environmentally friendly, and the UK leads the world in environmental standards, to the extent that many active quarries are havens for wildlife and important centres of conservation.
However, as most quarries extract materials below the water table, and as the UK experiences heavy rainfall throughout the year, water management and pumping are an important part of running an efficient and environmentally sustainable quarry. As quarrying exposes potentially harmful substances from the ground, it is essential that process and wastewater is handled, filtered, and purified effectively to prevent contamination of the water table, and reused as much as possible to reduce wastage.
Hazards from inadequate water management
Without efficient water management systems in place, a site may accumulate water from the ground during extraction, from wastewater used in the production process, or from washing down equipment after use. This water may contain contaminants and chemicals that may be harmful to the environment and human health.
Even without this risk, the uncontrolled discharge of wastewater into the public sewerage system may result in sediments and concrete blocking drains and bursting pipes, and various chemicals are lethal to wildlife and trees. Although thankfully rare, several UK quarries have been the centre of expensive environmental clean-up operations and bad publicity in recent years, and the risk of an ecological and PR disaster is never far away for quarry operators. The deliberate or negligent release of pollutants into the environment can result in heavy fines and the shutdown of the quarrying operation.
How Water is Used on a Quarry
Water serves a variety of purposes in a quarry and is often used in high volumes. Water is required for washing the aggregate, for example, as well as for vehicle wheel washing and dust suppression, and often the quarry needs dewatering to expose the material to be extracted. Water can be stored in lagoons or tanks on site and, after treatment and filtration, can often be recycled and reused multiple times. Filter presses and thickener tanks are used to remove silt and solids and treated water can usually be discharged into surrounding watercourses – subject to a strict quality and quantity control system.
Water Management Applications
The following is a brief guide to the main water management applications found in quarries:
1) Water extraction/dewatering
Water accumulates in quarries from groundwater seepage, rainwater, and run-off from surrounding fields. This has to be removed – in a continual process known as dewatering – in order to enable mineral extraction and prevent contaminated run-off. Depending on the water table level and the amount of precipitation, large volumes of water may need moving over a long period of time. This water may contain sediment, silt, or aggregate particles, and operators may not have access to electric power, so a range of pumping equipment is required:
Equipment: Slurry pumps, dirty water pumps, pontoons, borehole pumps
2) Aggregate washing
Extracted aggregate needs washing and sorting, so wash plants are used to remove materials from the aggregate, producing saleable material. Wash plants require a high-pressure water feed, often water recycled from other uses on the quarry. A powerful centrifugal pump is usually used to supply this water.
Equipment: Submersible pumps, filtration systems, sediment tanks
3) Sump management
A sump is a depression or pit where wastewater and run-off congregate, forming a mixture of slurry, groundwater, and general drainage water. Because of the high solids content of quarry water, sumps quickly fill with silt and sediment, which must be segregated and removed from the water using submersible pumps to keep the sump operational.
Equipment: Your sump pumps need a variety of heads to manage the demands of water management in different quarries, and in different weather conditions.
4) Solids separation
Cyclones separate lighter from heavier particles in liquid slurries. They are ideal for extracting further aggregates from dirty water. Settlement lagoons and thickener tanks are also used to produce water free of solids. Heavier liquids and mud may require a centrifugal slurry pump.
5) Fluid movement
Moving water and slurry around the quarry and through different elements of your water treatment system requires a variety of specially designed pipes. Many quarrying operations use durable rubber-lined pipework for the ideal combination of strength and abrasion resistance. This enables a steady flow of fluid throughout the pipework and minimises wear and tear. The modular construction of most quarry pipework systems enables the fast replacement of individual components and sections, and the upgrade or reorganisation of the pipework when required.
Dredging involves the extraction of sediment and silt from a lagoon or lake at the bottom of the quarry, and its removal (through a series of pumps and pipes) to a different location, such as a processing plant. Dredging machinery is sometimes used for material extraction in sand quarries, using specialised floating dredgers. In other operations, dredging is used for silt removal and discharge management.
Equipment: slurry agitator, dredger, submersible dredging pump
7) Wheel washing/vehicle cleaning equipment
Construction vehicles and mobile plant pick up a lot of mud, silt, and undesirable materials on their tyres, which must be removed before the vehicle leaves site. Failing to do so can inhibit the performance of the vehicle and pollute public roads. Wheel and vehicle washing equipment sprays vehicles clean as they enter or exit the quarry site, often as a drive-through washing bay, with water pumped from a storage tank or lagoon nearby.
Equipment: water storage tanks, transfer pumps, pipework, wheel washing/vehicle cleaning bay
8) Dust suppression
Quarries become dusty environments in dry weather, with dust churned up by equipment and vehicles posing a health hazard to workers and people living in neighbouring communities. Dust caused by extraction processes (e.g. blasting) may contain silica particles, which are linked to a wide range of respiratory health conditions, so it is important that measures are taken to suppress dust on site wherever possible. The most effective way to do this is to blanket the operating area with a fine water mist fired from fixed pipework or a mist cannon. The clean water required is supplied by a high-pressure pump.
Equipment: mist cannon, water transfer pumps, pipework
9) Thickener underflow
Quarry water is a solution of water and suspended aggregate particles, and as part of dewatering, the slurry or wastewater must be thickened in a special tank to allow the sediment to separate naturally from the lighter water. This happens in conical thickening or sediment tanks, where slurry is placed in storage to allow the silt to settle out. The excess water can then be pumped off the top of the tank, and the solid slurry moved to a processing or recycling plant.
Equipment: slurry pumps, centrifugal pumps, screw pumps, peristaltic pumps, conical sediment tanks, pipework, cyclone pumps, wash plant
10) Water discharge management
The discharge of industrial process water into the public sewer or an open water source is heavily regulated by the Environment Agency, with a strict monitoring system in place to assess the quality of water treatment and management systems. Before you discharge water from a quarry, you will need a permit from the local Water Authority, which can take up to nine months to secure. To acquire the permit, you must demonstrate you have the systems in place to control water quality on site, and to treat process water effectively.
Even after permits are obtained, quarries are now required to provide proof of safe water disposal and audits and quality checks are regularly carried out by the Environment Agency. For this reason, many quarries invest in an environmental monitoring system, which monitors and reports on water quality on-site. Modern systems can be configured to send automatic alerts if unsafe water contamination levels are detected, allowing rapid intervention to prevent pollution. By monitoring water quality on an ongoing basis, the management system ensures that all water on site is safe to dispose of and is treated appropriately to free it from contaminants.
Equipment: A full environmental monitoring system includes a wide range of tanks, pipework, and machinery, including dosing units, control modules, monitoring systems, treatment tanks, and pumps to facilitate fluid movement.
Tough Machinery for a Demanding Industry
Equipment to enable quarry operators to remain compliant with the country’s strict environmental and safety standards is becoming an increasingly important aspect of quarry management. Quarries are a demanding environment and require durable, high-performance equipment that can withstand the toughest and most rugged applications, whatever the weather.
If important machinery develops a fault or goes off-line, the entire quarry operation could grind to a standstill for hours or even days, costing thousands in lost revenues. It is essential, therefore, that quarry operators have access to a rapid supply of spare parts and reliable machinery, as downtime can be very costly.
- Borehole pumps – vertical multistage borehole pumps operate at high pressure and are extremely efficient at supplying clean water for quarrying sites.
- Centrifugal slurry pumps – slurry pumps allow suspended solids to pass through the pump without impeding operation and should be used when there is a large amount of mud or aggregate contamination. Slurry pumps come with a range of mechanical seals for different applications and must be regularly lubricated to optimise performance and service life. While some older models require manual greasing, many modern pumps can be fitted with automatic greasers to ensure consistent lubrication.
- Dirty water pumps – if there is a low level of solids in the water, a water pump will provide greater throughput and higher efficiency than a slurry pump. Water pumps designed for use on quarries are equipped with heavy duty seals, vortex impellers, agitators, and replaceable wear plates, to provide easy maintenance and fast repairs.
- Submersible pumps – come in a range of sizes and specifications and can be used for various applications in quarries. Many submersible pumps have inbuilt strainers to avoid the pumps becoming clogged and have chrome parts and double-sheathed cables for maintaining safety underwater, and to prolong service life.
- Peristaltic pumps – a peristaltic pump uses pressure to create a vacuum inside a pump hose, forcing fluid out and simultaneously sucking new fluid in. Once the process is set in motion, peristaltic pumps are extremely energy efficient, and have fewer moving parts than many mechanical pumps, making them less susceptible to breakdowns. These pumps are ideal for low-flow, high-pressure applications and can handle a high solids content.
Sustainability and Efficiency
Sustainability and decarbonisation are an increasingly pressing issue for the building supply industry. Many quarries face scrutiny over their water management practices – in particular the way in which wastewater is handled and reused within fluid management systems. And, with diesel fuel getting more expensive following the ban of red diesel from quarries, many quarry operators are faced with a quandary over how to simultaneously control operating costs and improve their sustainability profile.
Both energy efficiency and water conservation have a direct impact on your choice of equipment when specifying quarry water management plant for your operation
Diesel or electric power?
Many pumps designed for the construction and mining industries assume the presence of mains electric power, but these are not always available in remote areas on quarry sites. With this in mind, many quarry grade pumps and water management machines have an inbuilt diesel-powered engine, or use a stand-alone diesel generator.
Electric pumps are generally more energy efficient than their diesel counterparts and are more reliable, but diesel-powered pumps are more convenient on quarries in the absence of an electric power source. Diesel emissions are bad for the environment and diesel is becoming more expensive, whereas electric pumps can be powered by 100% renewable energy and help towards the industry target of achieving Net Zero carbon emissions. Sometimes the cost savings achieved by switching from diesel to electric power are sufficient to cover the cost of laying the electric cable to where the pump is required in less than a year.
At Atlantic Pumps, we offer a range of energy efficient pumps that consume up to 20% less energy than other models, while sustaining the output you need for efficient water management on site.
Sustainable water management
Quarries are intensive users of process water, but this does not mean that water management practices have to necessarily be inefficient, wasteful, or irresponsible. Modern quarry water management and pumping systems aim for a ‘closed loop’ solution, in which water is continually repurposed without having to leave the quarry. These systems also harvest the water from rain and run-off for reuse on site, minimising the need to use mains water sources to operate pumps and equipment.
Improving the sustainability profile of quarries reduces the environmental impact of operations and also helps cut energy and water use, leading to lower operational costs, with less waste and greater efficiency.
Specifying the Right Equipment for Your Quarry
There are a wide range of water management machines and pumps available to quarry operators, and many manufacturers specialise in producing high quality and robust equipment for the quarrying and mining sectors.
A quarry may need to specify different specialist pumps for various fluid management tasks within the system, for example:
- Site dewatering/run-off management – you may need to invest in high-capacity dewatering pumps to remove excess rain or floodwater from site. Some models offer a throughput of up to 5000 gallons per minute.
- Process water handling – specialist pumps are required for transferring water throughout the system. These should have a high head capability and feature wear resistant components to avoid maintenance issues.
- Slurry and mud management – most quarries require robust pumping equipment for handling slurry, mud, and suspended solids in wastewater.
Any equipment you purchase must be compatible with your project/operational budget, and consideration should be given not just to the upfront investment cost, but also to the lifetime cost of ownership. The best equipment is not usually the cheapest, but investing in high quality, energy efficient, and environmentally sustainable pumping equipment always provides better long-term value than cheaper alternatives, especially when supported by an appropriate PPM schedule.
The essential consideration when investing in plant for a quarry is to minimise downtime, as even a short unscheduled shutdown can be catastrophic for production. Therefore, always choose equipment purposely designed for quarries, with parts that can be rapidly swapped out, and ease of access to vital components to enable on-the-spot repairs.
You should also assess how well the equipment performs under pressure, and especially its resistance to water, impacts, temperature fluctuations, and exposure to chemicals.
Pump Maintenance and Asset Management
One of the keys to effective asset management in quarries, with a subsequent reduction in wastage and costs, is regular proactive maintenance. If an important component fails, such as a submersible pump, the entire operation can grind to a halt while the cause is identified and rectified – potentially costing thousands in lost production.
Planned maintenance and repairs
Arranged maintenance and downtime is always less disruptive than having to respond to un-scheduled repairs, so a planned preventative maintenance (PPM) schedule is one of the best ways of increasing your ROI from water management plant and preventing downtime.
PPM services are available from many quarry pump suppliers and servicing companies on a flexible and contractual basis, and avoid you having to employ additional pump engineers in-house. When emergency repairs are unavoidable, parts should be replaced with manufacturer-approved components like for like, or upgraded if available, and installed by qualified pump engineers. The schedule should pay attention to the manufacturer’s guidelines for component replacements and cleaning for each item of plant.
Monitoring and automation
Monitoring systems, which can be retrofitted to many types of pump, provide a good early warning system for wear and tear, allowing you to schedule maintenance at a convenient time. Unexpected changes in flow rate, water level, head, efficiency, or pressure could be a sign of a fault and should be investigated as soon as possible.
Inadequate lubrication is one of the main causes of pump failure, so a cost-effective way of extending the service life of your equipment is to invest in an automatic lubrication system. Once retrofitted to your centrifugal pumps, the device applies regular greasing for efficient operation, avoiding both over- and under lubrication, and saving precious man-hours.
A basic visual inspection can identify many of the main causes of critical equipment faults at an early stage– such as loose fixings, worn out belts and pulleys, and cracked mountings, allowing components to be replaced at scheduled intervals and avoiding unnecessary downtime.
- Check glands for leaks and ensure your bearing cartridge seals are not compromised.
- Check that the seals and bearings on your centrifugal pump are adequately lubricated.
- Check mounting points for looseness and fixings for cracks. These can increase vibration levels and damage your pump if not addressed.
- Check that your belts and pulleys are not frayed or worn out.
Appendix: Glossary of Fluid Management
This glossary explains the key fluid mechanics terms you may encounter when specifying a pump for quarry water management. Comprehensive glossary can be found on our Atlantic Pumps website, and if you are unsure, please don’t hesitate to get in touch with one of our technical sales team for clarification.
- Pressure: Pressure is the force that pushes water or other fluids through a water management system, essentially determining the flow rate. Pressure is measured by the force exerted by the water/fluid on the surface area, usually given in pounds per square inch (PSI).
- Flow: The output rate at which a fluid progresses through the system, given in cubic feet per minute, litres per minute, gallons per minute etc.
- Velocity: A measure of how fast a fluid moves through the system in a given unit of time, e.g. X metres per second, cubic metres per hour etc.
- Head: The latent mechanical energy stored in a contained fluid due to exerted pressure – e.g. from a pump, measured as energy per pound (or other unit) or fluid. Head is determined by measuring the vertical height of a fluid liquid column, with the ‘static head’ being the maximum achievable height (and pressure level).
- Performance curve: A line graph representing the head versus flow rate for a specific pump.
- Friction head: The pump pressure required to counteract the friction generated by the inside surfaces of the pipes, pumps, and fittings in a water management system.
- Pipe friction loss: A loss of head caused by friction between the fluid mass and the inner walls of pipes, fittings etc.
- Pressure drop: A difference in pressure between two areas in a fluid management system.
- Efficiency: The output power of a piece of equipment – e.g. a pump – divided by the power produced by that equipment, given as a percentage. In water management systems, the pump produces kinetic energy that is transformed into pressure energy in the fluid, which then goes on to produce volumetric pressure. The greater the percentage of energy conserved as output, the more efficient the system. Some loss is inevitable. Due to friction, a system can never achieve 100% efficiency.
- Best Efficiency Point (BEP): The optimum efficiency achievable by a system in which as much input (kinetic energy) as possible is converted into output (pressure).
- Net Positive Suction Head (NPSH): A measurement of the total head of a fluid on the suction side of a centrifugal pump. Although used as a pressure measurement in hydraulic systems, NPSH is given as a head measurement in feet, metres, or inches etc, and is independent of the fluid density. NPSH measurements are important to avoid flashing, or the vaporisation of fluid as it enters a pump, a process that causes air bubbles to form within the liquid which then collapse during cavitation. The shockwaves caused by cavitation place strain on the seals, fittings, and valves in your system and increase the risk of damage over time.
- NPSH-R: Net Positive Suction Head Required is the minimum suction pressure needed for a centrifugal pump to operate effectively, while avoiding flashing and cavitation.
- NPSH-A: Net Positive Suction Head Available is the amount of suction pressure available, minus the vaporisation pressure at the suction side of the pump. This should equate to or exceed the
- NPSH-R, ideally with a safety margin of 10% or more.
- Specific gravity (SG): A measurement of the density of a fluid compared to that of water at 4°C.
- Viscosity: A measurement of the resistance of a fluid to flow rate and applied forces, and the pressure this fluid exerts on the interior surfaces of pipes, fittings etc. A high viscosity fluid will exert more friction on the containing surfaces, resulting in a lower flow rate, and will require a greater energy input to achieve the same flow throughput as a lower viscosity fluid.