From Brown to Green: Transforming London’s 2012 Olympic Park
In July 2005, British crowds cheered as the city was selected to host the London 2012 Olympic and Paralympic Games. London 2012 will be big. Roughly 14,700 Olympic athletes from 205 nations and 4,200 Paralympic athletes are expected to arrive for 46 Olympic and Paralympic Games in 55 venues within 77 days. The City will host more than nine million ticketed visitors with nearly 250,000 visitors expected daily during the peak of the Games, which will be held July 27 through August 12 (Olympic Games) and August 29 through September 9 (Paralympic Games). As soon as the City’s celebration ended, the Olympic committee began work on the goals of creating the “greenest” and most sustainable games ever held, and of leaving behind a lasting legacy for the City.
The Olympic Delivery Authority (ODA) selected Atkins Global as the official engineering design services provider for the 2012 Games. Atkins’ charter included engineering design and delivery of the site’s enabling works – the preparations a site undergoes before it can be developed. The firm, under its ODA enabling works contract, was responsible for managing the investigation, remediation and preparation of the 2.5-square-kilometer (nearly 1-square-mile) Olympic Park site before construction of sport facilities could begin.
Atkins was appointed as project manager for the enabling works in 2006. Between October 2006 and December 2011, the firm worked with a team of experts to complete a nearly impossible job – transforming a brownfield with derelict industry dating back hundreds of years into the site of the Olympic Park, the very center of the games. The job included the United Kingdom’s largest soil washing project ever undertaken. As a lasting legacy for London, and as part of the overall Olympic plan, Atkins also helped to create one of Europe’s largest new parks with restored wetlands, meadows and wildlife habitat.
A team of 50 Atkins professionals – engineers, project managers, ecologists, soil scientists and sustainability experts – worked together with a number of subcontractors and team partners under extraordinarily tight deadlines to deliver the site. Below are some of the obstacles encountered with solutions for how they were overcome.
The Land of Fridge Mountain
The Lower Lea Valley in East London was an underserved community with low-income housing and derelict industrial areas, some of it heavily contaminated. It has become the main London 2012 site with the new Olympic Park.
The River Lea runs north through the site and conjoins with the River Thames in East London. Railway lines and waterways criss-crossed the site, which left very little green space for wildlife habitat. Many waterways were clogged with debris, invasive weeds, shopping carts, tires and household refuse. The site was known for its notorious “Hackney Fridge Mountain,” a towering 20-foot heap of castaway appliances reputed to be the largest “Fridge Mountain” in Europe. Centuries of soil build-up had raised the ground level by as much as 10 meters (33 feet) in some places. Buried glass, rubble, animal bones and war time demolition materials contributed to the mounds.
Water channels and only three connector bridges separated and isolated the Lea Valley community from other towns to the west and east, though the park site is only a few miles from Canary Wharf – one of London’s financial centers – and the Docklands, a thriving commercial and residential area. With the award of the 2012 Games, however, this moribund section of the London landscape would change dramatically and the two areas would become linked with increased access.
Site Remediation & Soil Washing
The transformation of the Lower Lea Valley first required an extensive site evaluation. Atkins prepared the environmental impact assessment (EIA) of the London 2012 Olympic, Paralympic and legacy facilities. An environmental statement accompanied the planning application; the 10,000-page document was one of the largest planning applications in Europe.
During assessment, a wide scope of environmental factors were considered, which included land contamination, aquatic/terrestrial ecology, flood risk, air quality and noise. Cultural heritage was also evaluated and included management of archaeological excavations on site. Among things unearthed during the remediation process were an Iron Age cemetery with four skeletons, 4,000-year-old flint axes, World War I gunning posts and a Roman river wall.
To discover and assess the nature of soil contaminants, the Atkins team drilled more than 3,000 exploratory holes across the park site. Chemicals, glue and various other industrial landfill debris had tainted the underlying soil and groundwater. With this information, the ODA and Atkins then developed a remediation plan, which divided the park into zones so that sport facility sites that required longer build times – such as the Olympic Stadium – could be completed sooner. With the EIA finalized and a remediation plan approved, businesses, residents and even wildlife species were relocated before more than 215 buildings were demolished across the park site.
One of the ODA’s goals was to reuse as much soil and material at the site as possible. The ODA had determined that 90 percent of materials should be re-purposed or recycled. Recovering contaminated soil for reuse, however, was a difficult problem. Atkins agreed to retain at least 80 percent of the soil on site in part because of the carbon dioxide footprint trucks would have left by hauling contaminated soil from the area. Truck traffic would also have contributed to city congestion, and finding landfill sites willing to accept contaminated materials would have been difficult.
A cut-and-fill strategy was settled on, so importing and exporting bulk material wouldn’t be necessary, and the excavated materials would be used to build foundations beneath several sport venues. As much as 80 percent of the highly contaminated soil had to be cleaned first to meet building requirements. To manage the huge remediation project, the site was divided into north and south sections. Morrison Construction and Bam Nuttall won the clean-up contracts for the job. A variety of techniques were used, including bio-remediation, soil washing and chemical and geotechnical stabilization. Atkins set up two “soil hospitals” where excavated contaminated soil could be brought for further testing, processing, treating and blending to render soils suitable for reuse.
Soil was divided between five washing plants to treat contaminants. Physico-chemical technology removed a wide range of organic contaminants (petroleum and polyaromatic hydrocarbons) and inorganic contaminants, including heavy metals, arsenic and cyanides. The remediation of Olympic Park became the United Kingdom’s largest ever soil washing operation: Two million tons of contaminated soil was chemically stabilized and bio-remediated.
Because of the monumental cleaning effort, 2.3 million cubic meters (81.2 million cubic feet) of excavated soil could be reused for earthworks or was recycled as fill material for construction.
Once soil had been cleaned, a 600-millimeter (23.6-inch)-deep layer of soil that met the highest remediation levels was spread across the site to protect human health. Beneath this covering, the underlying soil was treated to meet varying levels of remediation depending on how the land will be used in the future. Upon completion of the job, Atkins exceeded its goal of 80 percent soil reuse by 10 percent, thus delivering 90 percent of remediated soil for reuse. In total, 98 percent of the materials from demolition at the site were reclaimed for recycling and reuse.
Cleaning Groundwater with Ammonia-Eating Microorganisms
High levels of contamination were also found in the groundwater beneath the site. Contaminants included polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). In some parts of the site, groundwater was pumped through a treatment plant for processing and elimination through the sewer. In other parts of the site, a new bio-remediation technique was applied for the first time in the U.K. To remove ammonia from water beneath Olympic Stadium, Archaea – microorganisms that thrive in extreme conditions and which biologically degrade ammonia – were inserted into boreholes. While Archaea ate ammonia, reagents, including oxygen-released compounds, were injected into other groundwater areas on the site. A more permanent cut-off wall was installed near the new hockey stadium to lessen contamination.
All in all, the Olympic Park enabling work was complex, demanding well-coordinated work teams, maximum efficiency and adherence to tight schedules. As areas of remediation were completed in the order determined by the ODA and Atkins, they were handed over to other ODA partners to begin construction. The approach was so successful that Atkins was able to turn over the sites of the Olympic Stadium and the Aquatics Center in 2011, ten months ahead of the original schedule.
Europe’s New Park & Destination
Concurrent with the soil remediation work was the implementation of a program to revitalize more than 3 km (1.9 miles) of rivers and canals weaving through the site and to create an urban park that would endure long after the London 2012 Games come to an end. While the southern part of the park site is urbanized, the northern part has less development and became the focus of more intense environmental restoration. The ODA’s master plan for the Olympic Park included the restoration of 2.6 km (1.6 miles) of river bank along the River Lea to a more natural state for enjoyment by both the public and local wildlife.
Before the banks were re-created, river flows and velocities were measured at different locations, and the data collected was entered into a sophisticated hydraulic model to predict flood risk. A lock had been built in 2008 to improve navigation along the River Lea by preventing tidal water from flowing inland. But twice a day, when the lock was closed, the water level fluctuated by 400 meters (13.1 feet), which could lead to flooding along the river banks. To deal with the problem, Atkins changed the slope of the banks to 1 in 2.5 – about 22 degrees – and raised the height of the path up by 1 meter (39 inches). The lowered banks were also chosen to draw people toward the river to enjoy the new and restored riparian environment.
While newly graded slopes along the River Lea in the northern section of the Park were made ready for planting, concrete-lined water channels built in the 1940s were reconstructed and improved for the urbanized southern section of the park. Invasive plants were removed throughout the site.
Landscaping the restored banks presented special challenges. New plants had to create an attractive display during the 2012 Games and help stabilize the river banks as well as create wetland habitats that attract birds and wildlife. Moreover, the plants had to withstand the fluctuations of the River Lea twice a day along with its heavy silt deposits.
There were also targets for each different type of habitat. To determine the best plant species for use, Atkins devised a test with a 12-month trial planting along a 50-meter (164-foot) wetland area. Different species were planted at different elevations along the river banks and different bio-engineered installation techniques were applied during the test.
It became clear that grasses and sedges, yellow irises and purple loosestrife would fare well over time if planted in coir (coconut fiber matting) rather than if planted directly in the soil. Salix Nursery grew nearly 380,000 individual plants, which were delivered on 300 trucks, each with 1,000 pallets and detailed descriptions of where to install the plants. For greater control during the landscaping, river banks were planted via pontoon. The flowering plants will bloom during the Games.
Biodiversity for Thriving Habitats
Even brownfields can include diverse plant and wildlife habitats. Development of an Olympic Park Biodiversity Action Plan (BAP) was one of the planning conditions for the park’s development and provided a blueprint to create sustainable wildlife habitats, which might also attract and encourage other species to nest and thrive.
Atkins’ work has played a major role in protecting, conserving and encouraging the biodiversity and habitats within the Olympic Park area. Before buildings were demolished and soil remediation began, the site’s bird species and animals were cataloged, tree cuttings and seeds from native vegetation were collected for replanting, and some species, including newts and fish in small creeks, were removed to other locations during the remediation process. Woods, wetlands and meadows were created – and even a rare wet woodland habitat to support willow, alder and black poplars.
Atkins worked with a number of environmental organizations, including Natural England and the Environment Agency, to protect indigenous wildlife and to attract new species to the area. Species include the brown banded carder bumble bee, tumbling flower beetle, European eel and five bat species. Amphibians include: the common frog and toad, and the smooth newt; reptiles include the common lizard, grass snake and slow worm. Voles will be re-introduced to the river banks. It is hoped the site will also attract otters and Kingfisher birds. Fifty nesting boxes were installed for Black Redstart thrushes – a bird species of very limited number in the U.K.
A Legacy for All
Leaving a legacy after the games are over is one of the commitments that won London the right to host the 2012 Olympics. The creation of one of Europe’s largest parks, including certain habitats, is essential to that commitment.
After the 2012 Games end, it will take approximately one year to transform the site from the largest sports attraction of 2012 into an inviting public park. The park will have two very different parts: The South Park will be more urban with lawn and mature trees; the North Park will have a more natural setting with wetlands – much as it might have looked before industry arrived. A walkway, used by pedestrians to access the Olympic Stadium during the Games, will be removed so woodland can become further established. Buildings left in the park, including the velodrome and basketball venue, will be screened by trees to provide the feeling of a more rural setting. Woodlands will grow a magnificent tree canopy while the wetland area will thrive.
To protect the nascent wetland, Atkins designed a system that will allow water to overtop a section of riverbank once every four weeks. Due to the design of the park and the original planning, there will be little need for maintenance in the future. In fact, the park will be left to grow and flourish with the minimum of interference. Throughout the long term, the Olympic Park will be key to revitalizing this section of East London and will continue to honor the spirit of the games as a destination for recreation and inspiration.