Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Army base expansion - Undercover mission

Environment - When the Army set out to expand a training range set in one of the UK's national parks, conflict with locals looked inevitable, says Ruby Kitching.

National parks are peaceful, beautiful, unspoilt.

Northumberland National Park Authority describes its own protected landscape as full of 'the burble of running water, the bleating of lambs. . . . a melody of gentle sounds moving through time and place'.

Otterburn training centre, meanwhile, is an area where the Army practices live artillery training with tanks and rocket launchers to the tune of gunfire and explosions.

Different places, you would think. But they are not.

The Ministry of Defence (MoD) military training centre at Otterburn lies in the middle of Northumberland National Park (NNP). The army has trained on the 32km by 16km site since 1911 with squaddies and conservationists living in slightly uneasy harmony.

But combat techniques and artillery have moved on in recent years and have been threatening irreversible damage to the parkland.

Soldiers now need to simulate battle using longer range rockets and bigger tanks, which in turn are served by larger teams of support vehicles. Otterburn has come under intensive pressure to accommodate larger, heavier and noisier artillery - to the alarm of local people and the park authority.

To meet the needs of modern war machines a £40M upgrade of the training range has been needed, involving strengthening and widening 40km of road, laying 28km of new stone track, and constructing two bridges, 46 firing points, a 5ha maintenance area with drainage, and 130 new accommodation blocks.

Consultant White Young Green (WYG) and contractor Mowlem are in the last stages of the project.

All the construction has had to be worked around live artillery training, 31 working farms, grazing livestock and 60 ancient monuments. With almost no allowance for visual intrusion on the park, or interference with Army training programmes, the potential for three-way conflict between Army, park authorities and construction seemed huge.

'The easiest way to do the job would have been to close the training centre down.

But instead we had to change our programme to fit around the army's activities, ' says Mowlem resident engineer Stephen Round.

After two public inquiries between 1997 and 1998 costing the MOD £10M, the Secretary of State decided in 2001 that training the army to use 'scoot and shoot' multiple launch rocket systems and AS90 self-propelled guns was more important than restoring the National Park.

But the inquiries did throw up 200 conditions for consent: None of the new roads are straight, to make them look more organic, and buildings are clad in traditional materials such as timber or stone.

Even pitched roofs are painted the same shade of green as trees in the background, and 70,000 new trees are being planted to camouflage parts of the development from key vantage points across the park.

Nor was there to be any visible evidence of road widening. WYG's solution was to peel back 2m of roadside vegetation to widen the 3m wide roads, lay new pavement, and then allow grass to grow back.

The firm dubs this the 'now you see it, now you don't approach'.

'We had to develop five different seed mixes to match existing verges to encourage a good blend between the new and existing vegetation, ' says WYG project manager John Gledhill.

Firing points which spur off the roads also had to be grassed over.

'The land would take 10 to 15 years to heal naturally, but the National Park wanted this to happen in less than a year, ' he adds.

Everything had to be designed with the view that, one day, the park could be returned to nature. The 28km of stone tracks in wooded areas had to be laid on geotextile so they can be easily removed when the time comes. Conventional roadside drains were also out: instead French drains have been adopted using locally quarried whinstone.

Engineers painstakingly surveyed the existing strength of what Gledhill describes as 'asphalted cart tracks' scattered over the training area to determine the minimum structural road depth required. This allowed the design to be specific to each kilometre of road, minimising ground disturbance. WYG also specified geogrid reinforcement to improve road strength without increasing its structural depth.

Main roads are surface dressed with Stone Mastic Asphalt (SMA).

But where roads branch to firing points, a concrete base is needed to resist the slewing forces exerted by tanks when they turn. WYG specified a mix with 10% cement replaced by microsilica for extra density. The Toproc mix, supplied by Tarmac, achieves 90N/mm 2cube strength after 28 days.

To accommodate NNP's strong objection to having sections of grey concrete breaking up the park's otherwise black roads, black concrete has had to be used, bumping up concrete costs by 250%. Otterburn's 5ha maintenance and parking area has been paved with the same material.

With so much newly paved area, inundation of the park's tiny streams with increased volumes of surface run-off water was a major concern. Reed beds have been planted to slow flow and a huge 3m by 3m culvert and 300m 3water attenuation system has been installed beneath the parking area. This provides capacity for interception of fuel spills of up to 45,000 litres.

'We had a big sledge hammer behind our backs if things went wrong, ' says NNP planning advisor Terry Carroll. 'If the reseeding didn't work, if the streams got polluted, if the concrete wasn't dark enough, the penalties would be high.'

The Otterburn project has also involved building berms and landscaping some areas to act as noise buffers during artillery training - a maximum 120dBa is allowed. And WYG has designed splinter-proof bunkers to withstand ricocheting bullets or shrapnel from explosions. 'We designed walls to take high velocity impact loads by half burying them and using high density masonry walls with concrete ceilings, ' explains Mowlem community liason officer Jane Braebrook.

Although Mowlem project manager Richard Trinick stresses that the project 'won't be finished until everything has grown back and the National Parks is completely satisfied', completion is scheduled for July 2005.

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.