The urban jungle

Atkins | 10 Jul 2009 | Comments

When staging one of the largest events in the world, you could be forgiven for not immediately considering the fate of the local flora and fauna – but it does matter. How do you prepare for something as big as London 2012 without disrupting the local ecology?

“Despite appearances, urban sites can support rich biodiversity. The Olympic Park is a good example of this,” says Kim Olliver, Atkins’ senior ecologist. She leads a team of ecological consultants working on the site of the future Olympic Park in the Lower Lea Valley in east London. A mix of industrial and often contaminated land, this area has been subject to decades of neglect. However, as Olliver points out, this does not mean its ecological importance should be underestimated.

“In pockets of wetland, woodland and waterway habitat, a variety of significant species has been found,” she says. “This has included rare invertebrates, Sand Martins and Kingfishers, bats and fish. It also features native trees such as the London Plane, which can be up to 70 years old. It’s essential that we preserve them wherever possible.”

Understanding the importance and value of even seemingly insignificant things lies at the heart of efforts to preserve and protect Britain’s ecology. Each species is adapted to its surroundings and each habitat is a web of species interaction. Upset that equilibrium and species may be lost, with effects that can cascade through the ecosystem.

With sustainability a major focus of the London 2012 Games, environmental considerations have been fundamental to the planning process. Before construction work can start on any project, developers must complete an environmental impact assessment, of which ecology is an important element. Working alongside organisations such as the Environment Agency and Natural England, Atkins has ensured that the interests of the local wildlife come first, while helping developers meet their legal environmental requirements with minimum disruption and cost.

“There may be planning constraints that contractors are not aware of, so it’s important that we guide them through that process,” says Olliver. “We provide advice to the client on what environmental assessments, monitoring and mitigation are required and how to implement the various measures as effectively and efficiently as possible.”

“Legislation such as the Natural Environment and Rural Communities Act and the Wildlife and Countryside Act are designed to prevent damage to the rare and protected sites around England and Wales,” says Rosemary Redmond, Environment Agency project manager for London 2012.

Redmond adds that the conversation about ecology has to start right at the beginning of the planning process: “Environmental considerations can be seen as a barrier, particularly when there are tight deadlines to deliver a project. We have been heavily involved in the sustainability and biodiversity objectives on London 2012 since the bid stage in 2004. We have been a key stakeholder for strategic and detailed planning documents including publications such as the Biodiversity Action Plan, the water space masterplan, and the parklands and public realm planning application. With early discussion and a proper understanding of the likely effects on a site’s ecology, any potential barriers can be successfully managed.”

Planning ahead can produce the best outcome for the species in question and minimise surprises later on, when delays to the schedule can have serious cost implications.

“Before you do anything, you have to know what you’re planning for,” agrees Olliver, who has been involved at the Olympic Park site from the outset. “You can put your own timelines in place, but any species living on the site will have their own schedules, whether it be nest-building, seasonal hibernation or roosting.”

As a rule, she adds, the interests of any wildlife come first, so project schedules must be planned accordingly: “If there are rare birds nesting on a pylon, the removal of that pylon will just have to wait.”

Putting down roots

Atkins’ ecology consultants work with clients across the UK on projects of all sizes, from preservation and translocation of entire habitats and populations – as at the London 2012 site – to smaller-scale survey work.

It can be a multi-organisational and multidisciplinary effort. Olliver liaises regularly on site with everyone from civil engineers and geotechnical specialists to horticultural experts and utility inspectors. She ensures that everyone understands their obligations with regard to a site’s ecology and to provide assistance where necessary.

One key area that Olliver is involved in is the remediation strategy to clear the site of invasive weed species. This includes Japanese knotweed, giant hogweed, Himalayan balsam and floating pennywort. These species are managed using environmentally sound techniques prior to construction.

The overall aim is to preserve the existing biodiversity or, better still, to improve it. At the London 2012 site, increasing biodiversity through the creation and enhancement of habitats has been central to the ongoing ecology programme. Nurseries have been planted with cuttings from those areas that will be lost to construction, in order that the finished site can be replanted with the original flora.

A 10,000sq m nature reserve has also been created near the northern perimeter of the Olympic Park, along the banks of the River Lea. It is intended that the diverse set of habitats contained within the reserve will become home to a variety of flora and fauna, including species not previously present.

Jason Lovering heads up Five Rivers, an environmental consultancy that has worked alongside Atkins on several projects at the east London site, one of which involved the translocation of a rare habitat to the new reserve.

“In one area of the Olympic Park there were some old railway sidings that had, over half a century or so, formed a diverse habitat for flora and supported rare invertebrates,” says Lovering. “It might not look terribly exciting, but this substrate was actually home to a species such as the toadflax brocade moth, which is targeted as a priority for conservation action under the Biodiversity Action Plan, so it was important that we made every effort to preserve it.”

The ballast and surrounding earth were dug up, loaded on to pallets and successfully translocated to the reserve. While this might sound like a simple albeit physical task, it was painstaking work.

“There was a risk that the aggregate would turn over during transport and the natural strata that make the habitat so unique would be disturbed,” says Lovering. “When you move turf, the root structure helps to hold it all together, but when the aggregate has a layer of fine silt, as was the case here, it can easily fall apart.”

Lovering also worked with Atkins to recreate an important invertebrate habitat, which would compensate for one lost during construction of the stadium at Stratford: “We moved some 300 cubic metres of earth from the new location and replaced it with a clay material, which provides the nutrient-

poor substrate required for what we call brownfield flora,” he says. “This flora – seeded from the original site – is essential to attract invertebrate species such as the brown-banded carder bee.”

The substrate was then surrounded by log walls, which were drilled with holes in order to encourage the bees to nest.

Linking it up

One of the biggest challenges when trying to avoid, or compensate for, the loss of species and habitats – especially when dealing with a large-scale project – is connectivity. A new or translocated habitat will be ineffective and unsustainable if the animal or plant species are isolated.

“Wildlife in a large city like London tends to exist in fragmented pockets, over a large area,” says Olliver. “When you create or move habitats, you have to ensure that the ecological connectivity is maintained or even enhanced.”

In the Lower Lea Valley, for example, the waterways that criss-cross the Olympic Park are important conduits for a variety of species, including Kingfishers.

The Atkins team has taken a transitional approach to work on the site in order that such networks are affected as little as possible. In the long term, conservation areas created on the London 2012 site will form part of the future landscape of the Olympic Park and will be linked to the wider countryside through natural corridors.

“Sometimes derelict and apparently unimportant urban environments can be vital to the survival of a species,” says the Environment Agency’s Redmond. “These sites often act as parts of much larger networks. Together, they allow the UK to hold one of the largest varieties of protected sites in Europe.”

“By having a thorough understanding of the ecology and the requirements at sites such as the Olympic Park, and by managing that efficiently, we can ensure that project delays and costs are kept to a minimum,” says Olliver. “Most importantly, we can help to make sure that the rich biodiversity of the UK is preserved and enhanced for generations to come.”

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