A civil engineering project for the construction of a new White Water Centre on a brown field site in the Lee Valley, Broxbourne, Hertfordshire. The new White Water Rafting and Canoe Centre formed part of the London Olympics, 2012. There are two white water courses, one intermediate, 150m long, and the other an Olympic course, 300m long. The courses are supplied with water from a constructed lake via two pumping stations sited at the lake perimeter. A bridge, supported on two bridge abutments, was constructed over the lake at its narrowest point. The lake has a perimeter of 1km with a maximum depth of 2.50m. Two conveyors were constructed in order to transfer canoeists from the lake to the start pools. A Facility Building was constructed to house the offices, changing rooms and visitors amenities. A boat store and plant room building was constructed beneath the Olympic start pool.

Lake construction:

The scope of works comprised the construction of an RC foundation base to the lake perimeter, a vertical curved RC retaining wall (varying in height from 1.50m to 3.00m) to the lake perimeter (1km in length), lake liner supplied and installed by a specialist, RC lake bed slab laid to falls to 1/3rd of the lake bed, natural stone (by separate specialist contractor) laid to falls to 2/3rds of the lake bed and feature battered profile concrete wall to the perimeter of the lake.

Olympic and Intermediate water rafting course construction:

The excavation for the channel and the installation of the channel liner was carried out by others.

The scope of works comprised the construction of an RC base laid to various falls, stainless steel channels cast into the RC base at 400mm centres, dowelled movement joint in the RC base at 20m centres, 12 number feature pools with radius steps for access, and infilling the perimeter walls between the feature pools with spray applied concrete to form a 30/40 degree battered profile finish.

Olympic and Intermediate pumping station construction:

The scope of works comprised the construction of a waterproofed RC slab, edge thickening foundation and RC walls, both curved and straight as a waterproofed RC sump structure, RC suspended roof slab to the sump with an RC Box over as the pumping station.

Construction of two bridge abutments:

The scope of works comprised the construction of RC abutment bases, RC abutment walls with a Class C finish and an additional vertical splayed featured finish cast on, the forming of recesses in the tops of the walls for the bridge bearing pads and the fixing of the pads in position. The precast concrete bridge deck was supplied and installed by a specialist contractor.

Further scope details

An official opening during early December 2010 was cast in stone as ramp up events were organised in preparation for the Olympics. This back stop date had to be achieved which was the main driver in our site programme.

The design for the appearance of the lake perimeter walling required a rustic feel that would blend in with the surrounding countryside. This was achieved by filling sand bags with a semi dry concrete mix then placing the sand bags on top of each other, dowelling them together with stainless steel dowels and removing the exposed face of the sand bags after the concrete had set. We used 5,000 number 2m long sand bags on this walling.

Stainless steel channelling at 400mm centres was cast into the reinforced concrete base of the rafting course. This was required for locating and securing the plastic shapes which generate the rafting waves and course layout/definition. Overall we cast in 10,000 m of stainless steel channel.

We constructed 12 number feature pools with radius steps for access. The purpose of these pools was to provide rescue access via the steps. We finished off the perimeter walls to the rafting course, between the featured pools, with a 30/40 degree battered wall constructed from spray applied concrete to form the profile.

The scope of work entailed:

• Site logistics management
  
• RC base to the lake perimeter
  
• RC curved retaining wall(1.50-3.00m high) to the lake perimeter (1km overall)
  
• Lake liner supplied and fitted by specialist
  
• RC lake bed slab to 1/3rd lake bed
  
• Natural stone as lake bed slab to 2/3rds lake bed – supplied and installed by specialist
  
• Concrete walls with ‘sand bagged’ rustic feature to the lake perimeter (5,000 number x 2m sand bags used) dowelled together with stainless steel dowels
  
• Channel liner to the rafting course supplied and fitted by specialist
  
• RC base to the rafting course laid to various falls
  
• Stainless steel channels cast in to the RC base at 400mm centres (10,000m cast in)
  
• Dowelled movement joints in the RC base slab at 20m centres
  
• Feature pools with curved steps for access – 12 number in total
  
• Form battered finish to perimeter walls to the rafting course by spray applying concrete to form a 30/40 degree profile
  
• RC foundation, base and walls to pumping station sumps
  
• Waterproof concrete additive to pumping station sumps
  
• RC suspended slab and RC box as pump stations
  
• 2 number RC abutment bases for bridge abutments
  
• 2 number RC abutment walls, fine finish type C with cast on vertical splayed featured finish
  
• Forming recesses in the tops of RC abutment walls for bridge bearing pads
  
• Drainage works
  
• External landscape works
  

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