Quarries are prone to nuisance water which must be manged to maintain productivity. When Aggregate Industries decided to expand one of their quarries, a new dewatering system was required to manage the increased flow of water and to ensure daily operations were maintained.

Covering 600 acres, Torr Quarry is the largest in the UK producing six million tonnes of construction aggregate per annum. Located seven kilometres east of Shepton Mallet, the quarry is an important source of sand, gravel and stone locally and reaches as far as the South East of England, where there are no similar resources.

When planning permission was granted for the deepening of the quarry, increasing its construction aggregate output to eight million tonnes per annum, Aggregate Industries needed to source a pumping system that could successfully manage the additional water handling requirements.

Speaking about the decision to source an additional pumping system, Steve Nice, Quarry Based Development Manager at Aggregate Industries, said: “Constant water clearance from the quarry is critical to its day-to-day operations. As the quarry reaches news depths, the additional ground water and rainfall it is subjected to, means it’s vitally important that we have the necessary system and equipment in place that not only ensures the quarry is efficiently dewatered but also that it doesn’t hinder daily procedures.

“There have also been a number of environmental issues that needed to be taken into consideration: With a lot of sediment at the bottom of the lagoon, we can’t simply pump directly into the water course. Allowing time for the water to settle plays a key role in the process of moving the water from the quarry into the river Avon, the chosen dewatering solution would have to take this into account.”

With this in mind, Aggregate Industries contacted Pump Supplies for advice, who in turn worked closely with its supplier Xylem Water Solutions to design an effective dewatering solution for Torr Quarry.

Rob Bessant, Contracts Manager at Pump Supplies, commented: “We conducted a full site review to determine the required additional capability and potential layout of the pumping system. With numerous needs for water within a quarry, such as stone cutting, it’s not just a case of implementing a system to remove nuisance water from site but also process water, so we had to take this into consideration when specifying equipment.

“We recommended the implementation of two sumps that would be used as settlements, each utilising two Flygt 3240 290kW c-pumps, two Flygt 2400 submersible pumps and one Flygt 2250 drainage pump.

“The Flygt c-pump has a double channel impeller enabling excellent flow passing properties that reduces clogging, which is vital for a quarry pumping system to maintain peak operational performance. The Flygt 2400 provides excellent wear-resistance and is capable of operating in the toughest environments, while the Flygt 2250 pump has a high flow capacity, excellent for dewatering quarries.

“The Flygt pumps have proven reliability in tough industries such as quarrying and we felt this design would offer the best combination of wear and clog resistance, as well as ensuring high efficiency. In addition, the settlements would allow the water to augment, ensuring all environmental regulations would be met.

“To meet the environmental challenge and ensure sediment would not be pumped into the water course and to maximise the efficiency of the pumping system the Flygt pumps were floated on tailor made pontoons, allowing the settled water to be pumped straight into the local water course. The advantage of using a pontoon to float the effluent pump is that it will pump from a set depth, floating on the surface of the pond. The level of the effluent in the pond does not alter the performance of the pump.”

Steve Nice concluded: “We are delighted with Pump Supplies innovative approach to our dewatering and pumping needs during this expansion. The bespoke solution, utilising effective and efficient Flygt pumping equipment, has ensured we can now reach new quarry depths whilst still maintaining peak operational levels.”