Land and Water have been contracted as main contractor for the design and construct marina relocation works and as specialist partner/subcontractor to Birse Civil Engineering Ltd for the rowing course works.

The project is funded via Sport England through the site owner, Caversham Lakes Trust, and will provide year round training facilities through the Amateur Rowing Association and other bodies.

In order to construct the rowing course to the correct depth and profile, Land and Water are moving substantial volumes of overburden that had been dumped on the floor of the flooded quarry after mineral excavation. This material is moved using combinations of long reach excavators on road transportable pontoons.

The material is then loaded into a series of purpose built split-hopper barges and redeposited on the backslopes of the perimeter bunds that bound the course or into deeper areas under water.

Digital, GPS controlled hydrographic survey linked from the survey vessel to the site offices and pusher tugs help provide the site team with underwater vision, insuring that excavation is restricted to the areas above profile and that dumping is restricted to approved disposal locations.

The perimeter bunds and cycle track are being constructed using sand and gravel won from dewatered borrow pits and from flooded areas of the site. In the flooded areas of the site a huge EX750 long reach excavator mounted on a jack-up pontoon is being used to side cast up to 4m of overburden to expose a seam of mineral below. The giant machine is fitted with an electronic dig control system that records every pass of the bucket to a proven accuracy of 30 mm. A real-time electronic link delivers this information to the site office, creating an underwater map of the top surface of the exposed mineral.

The mineral is then recovered by a further pontoon-mounted 44 tonne long reach excavator, again loading a team of Land & Water's road transportable split barges. A fleet of 250hp Schottel driven tugs then push the barges across the lake to the position of the proposed perimeter bund.

Here again GPS is used to position the tugs and barge over the exact location of the bund before the barge splits in half hydraulically to deposit its 170 tonne load onto the bund in under 60 seconds. The shallow drafted split barges bring the perimeter bund up to 1m below water level and the topping off is undertaken using conventional dump trucks and long reach excavators.

The project is currently on programme for completion by the end of this year, with the opening scheduled for next year after an adjacent facilities building has been finished.

MJ Information No: 18425