Kew Gardens

Aquablast Ultra-High Pressure Water Jetting


Case Study – the Temperate House at Kew Gardens

At the famous Kew Botanical Gardens, in west London, established by King George II in 1759, and now a UNESCO World Heritage site, one of the key repositories for part of this immense and unique collection of flora is the iconic Temperate House, the largest surviving Victorian glasshouse in the world.

Specialist Ultra High Pressure (UHP) waterjet company Aquablast played a key role in the restoration of this famous cast and wrought iron building, which, under the heritage conservation laws, has a Grade 1 listing, demanding that repairs and restoration are carried out under intense scrutiny and with the greatest care.

Opened originally in 1863, the Temperate House iron and woodwork has been deteriorating and so a five year programme costing £30m was carried out to restore the building to its former splendour.  It’s now fully open again to the public hopefully to survive for at least another 150 years.

After the precious plants had been safely removed to temporary new homes, thousands of panes of glass had to be removed so that the original, mainly cast-iron frame was fully accessible to remove multiple layers of old white paint and corrosion.

Aquablast at Kew Gardens

Picture: Aquablast’s Jet Edge UHP pumps at Kew Gardens

To minimise the environmental impact in Kew Gardens, 55,000 psi Aquablast UHP water jetting was chosen to strip the ironwork to create an ideal anchor pattern for the latest paint system, which is expected to last up to 25 years.

Aquablast were tasked by ISG, the project main contractor, to provide eight UHP waterjet lances for the task and so four of the company’s biggest UHP machines were brought into Kew Gardens for the four-month project.Andrew Watt, Aquablast’s Operations Director, commented:

“This was a challenging project for us.  It’s a very complicated structure.  We had 10 men rotating on 8 guns working 10 hours a day, often six days a week, for four months on a tight timescale.  I’m pleased to say that our equipment – and our men – performed near faultlessly.”

“Our UHP lances operate with very low water flows but very high pressures.  So this does not create unacceptably high reaction forces for the operators nor wastes much water. Because of the complex shapes and awkward angles which we had to waterjet in the Temperate House, this was an important advantage and reduced operator fatigue.”

Aquablast at Kew Gardens

Picture: Stripping years of old paint from the Temperate House cast iron roof struts

UHP water jetting has distinct advantages:

  • No dust – operators do not need air-fed hoods, only good quality eye protection and correct PPE;
  • Chlorides (salts) removed virtually entirely from the surface, a key benefit to ensure a long-lasting new coating system;
  • Detailed wrought ironwork entirely undamaged because of absence of blasting abrasive;
  • Absence of abrasives greatly reduced clean-up and disposal time and cost;
  • Minimal water consumption (c. 8ltrs/min per waterjet lance) so no special water supply or drainage arrangements 

Special membrane was laid in the building to collect the relatively modest rust and paint arisings.  The entire Temperate House, which at 630 feet long and 62 feet high (62m x 19m), extending to over 53,000 square feet (almost 5000 m2), was entirely encapsulated in a vast scaffolded enclosure which protected nearby priceless plants and trees and also allowed work to progress unaffected by weather.

Aquablast at Kew Gardens

Picture: No damage to the detail and dust-free

Kew Gardens is one of the top tourist attractions in London, attracting over 1.6m visitors annually.  Plants were brought back to England from around the world at the height of the British Empire for conservation and study and the botanical gardens is internationally recognised not just as a tourist attraction but for expansive research and science services related to the food and plant-derived drug industry.

Kew Gardens Project

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