When Land & Water Meet…
Land & Water operate the one of the largest fleet of long-reach excavators in Europe and have the UK’s largest fleet of inland floating plant, which includes tugs, barges, road transportable pontoons and Amphibious equipment, having first operated amphibious equipment in the UK back in 1998when they purchases a Hitachi MA125. Over the past four decades, this award-winning inland waterway and coastal civil and environmental engineering company, headquartered in Guildford in West Surrey, has become synonymous with finding creative and effective solutions to complex challenges in the specialist environment where land and water meet.
Often operating in complex or sensitive habitats, their work is always completed with sympathy to the local surroundings, people and the environment – and such was the case when we recently caught up with the Land & Water team working on Phase 2 of the Leeds Flood Alleviation Scheme (Leeds FAS2) in Yorkshire where it employed one of its specialist marine excavators, an amphibious long reach modified WK90 machine with a Takeuchi TB290 upperstructure.
A key supplier of strategic flood and coastal-defence projects throughout the country, the company works in partnership with some of the UK’s major contractors; who can forget the Somerset floods in 2014? Land & Water was the first to respond, mobilising 25 machines and 60 men and women to deliver the emergency flood response. On the Leeds Flood Alleviation Scheme it was employed by BAM to carry out a specific part of the contract that only the amphibious WK90 was best suited.
Amphibious excavators provide the crucial link between land-based excavators and floating excavators on pontoons. As a general rule, if the ground is soft and the water is less than 1m deep, then an amphibious excavator is often the most effective machine. Amphibious excavators can be fitted with additional side pontoons for working in deeper water which allow them to excavate against spud legs and give the machine increased stability.
As a midsized model of amphibious excavator, the 13 tonne WK90 can access all but the tightest of sites and is able to work in deep water with its side pods and additional floats. It has a hydraulically retractable undercarriage so it can be easily transported by road and there is no need for the additional cost or risk in assembly.
The machine is operated by Dave Chidgey who has many years of experience working with amphibious excavators and when BAM took on the contract they approached him to ask their opinion on how they should proceed in strengthening the river bank.
Without the amphibious the WK90, the job would
have been extremely difficult to successfully complete…
“Dave has been with us for some time, so his opinion in tackling tasks such as this is highly valued,” says Ben Clarke, Land & Water’s General Manager-Marine Plant. “We suggested how to go about it and what equipment was needed – that included the WK90, two tugs and a hopper. Initially there was a lot of clearance and remedial work to carry out before we could begin piling to reinforce the river bank. Once that was accomplished, we then had to re-profile the river bed back to its original state. Any challenges were quickly overcome, thanks to Dave’s experience on amphibious machines, and the capabilities of the WK90, without which the job would have been extremely difficult to successfully complete. In all, it took about four weeks to finish.”
Adds Ben: “We’ve had the WK90 for more than three years and it has been performing very well for us on this and previous contracts; it’s quite a niche machine which has become an integral part of our long reach and amphibious excavator fleet.”
The LFAS2 is a two-part scheme that aims to reduce flood risk and provide better protection for homes and businesses along the river Aire corridor between Leeds City Station and Apperley Bridge using a combination of natural flood management techniques and engineering works.
The scheme involves new flood defence walls and embankments, new flow control structures and pumping stations, a large flood storage area near Calverley, making use of an existing flood plain, a natural flood management programme to help reduce and control the flow of rainwater into the river using natural techniques, such as tree planting, removal of obstructions along the river to reduce water levels and local access enhancements and improved footpaths and ramps.
Leeds FAS2 is made up of a combination of catchment-wide natural flood management, as well as traditional engineering that stretches for 14km along the River Aire. It will reduce the risk of flooding to a 0.5% chance of occurring in any given year (a 1-in-200-year level of flood protection) for 1,048 homes and 474 businesses. This level of protection includes an allowance for climate change up to 2069 and will be effective for similar events to the Boxing Day floods in 2015, which cost Leeds an estimated £36.8 million and the city region more than £500 million.
One of the largest ever inland dredging contracts completed in the UK…
It’s not the only major contract that has involved the team at Land & Water – there have been many down the years, including another recent 18 month long project at Blenheim Palace in Oxfordshire where the team removed over 300,000 cubic metres – around 500,000 tonnes – of silt to restore the Queen Pool to its original depth of two metres. The area is a Site of Special Scientific Interest, which is often relied on for food by a variety of wildlife.
The famous man-made lake, built by Capability Brown in 1763, had become less than 30cm deep and if the project had not taken place, Blenheim Palace was at risk of the lake completely drying up within five years. The silt dredged by Land & Water is now being used to form a 16 hectare grass mound on the estate.
The team faced some challenges during the dredge which is one of the most ambitious projects undertaken at the site over the last 300 years and one of the largest ever inland dredging contracts completed in the UK. Not only were they battling with nature, they also came across old roads and infrastructure dating back 1066, which meant the site had to be shifted 50 metres whilst archaeologists investigated the findings, which has been determined to be an old Saxon Mill.
The dredge was strategically designed to minimise the impact on the environment and the Estate as a whole. Land & Water commissioned several pieces of equipment to enable higher production in the shallower water.