Pumping station

Olympics Watch - Zero-waste Games

From brown-field site to Olympic Games venue to legacy function, E&T investigates the processes and methods involved in designing-out waste at the London Games location.

All waste projects are similar but no two are exactly the same. The Olympic Park project in London, UK, is a four-phase challenge. First, the 2.5sq km site had to be cleared and cleaned, and waste water and sewage facilities have to be installed, before a whole other sequence of challenges will arise. Throughout the 77 days of the Games, 17,000 athletes, 20,000 journalists and up to 800,000 spectators and visitors will pack into the Park. After this, it subsides into legacy mode – the Plan, the Clearance, the Realisation and the Deconstruction.

The ambitious mission statement of the London Organising Committee of the Olympic Games (LOCOG) was 'to deliver zero-waste Games'. It aimed to design-out waste and listed a waste hierarchy of reduction, reuse and recycling, with landfill as a last resort. It aimed to reclaim 90 per cent of material from demolition for reuse and recycling, using 25 per cent for construction, and to strive for a high recovery rate during deconstruction following the Games.

The UK might have been overjoyed when London won the bid for the Games in 2005, but it must have been a daunting task for the people who had to realise it. The Olympic site was once a brown-field urban landscape with active and disused light industries, houses and allotments. It was partitioned by canals, roads and railway lines, as well as 192 buildings. From the end of the 19th century, it had been used for landfill and deposits of oil, tar, cyanide, lead and low-level radioactive materials were detected.

Atkins won the enabling works contract to clear the site in 2006. Project manager Mike McNicholas remembers the difficult early days: 'There was no planning permission for the whole park, and people were still moving out. To enable fast decision-making and constant communication with the client, local planning authorities, regulators and contractors, Atkins pulled in experts from throughout the UK and co-located them in a single project office in London. Managers were brought in for their leadership skills, rather than their technical knowledge.'

As occupied buildings were emptied, teams carried out 3,000 site investigations to locate the various types of waste. All buildings had to be removed, but not all were demolished. Simon Wright, director of infrastructure for the Olympic Development Authority (ODA), says that eight were moved to other sites, one went to Ireland and another became an AIDS charity warehouse in Tanzania. As for the reclamation target, Saphina Sharif, Atkins's site director, always believed that it was achievable: 'We knew the target was challenging, but believed that with careful thought and organisation about the demolition, we could achieve it.' In fact, over 98 per cent of demolition materials have been recovered.

Cleansing

Anthropologist Mary Douglas said 'dirt is matter in a different place'. Waste, too, is often in the wrong place.

First, contaminated soil has to be cleansed. A whole range of techniques were used at the Olympic site, depending on the nature of the contamination – soil washing, chemical stabilisation, geotechnical stabilisation, bioremediation, complex sorting, primary screening, crushing, and on-site burial.

Soil could not just be 'dumped', it had to be taken to a soil laboratory for testing. Sixty scientists and specialist staff used an on-site laboratory to work out the best form of treatment. A 'soil hospital' consisting of five huge soil-washing machines cleaned and agitated the soil. Contaminates were removed from coarser particles of sand and gravel and mixed with silts and clay; large lumps of metals were extracted by magnets from the contaminated soil. Coarse gravels were separated at this stage and clean sand was filtered out for reuse. The remaining mixture was pumped through sieves, mixing blades and water sprays. In some cases, bacteria and fungi were used for cleaning. Warm air and water vapour were pumped through the soil to accelerate the breakdown of contaminants by encouraging bacteria to breed in the soil. The water was then treated and used again.

Eighty per cent of the soil was used to raise banking areas of the Olympic Park. Any soil that was too contaminated was sent to a licensed landfill. 'In total, we've cleaned nearly two million tonnes of contaminated soil, which makes it UK's largest ever soil-washing operation,' says Sharif.

To stop oil spillage contamination, a contractor introduced a 'plant nappy' to replace metal drip trays under machinery. When it rains, oil and water mix and spill onto the soil. When oil drips onto the plant nappy, it is filtered through to its base where it binds to a sponge. Rain cannot penetrate the filter, so only water spills out on to the ground.

Toxic waste

A small amount of soil containing traces of low-level radioactive material, classed as 'exempt' under current environmental law, has been safely buried in a cell under a bridge embankment on the Olympic site, says the ODA. It is covered and capped on all sides. The Environment Agency says: 'Overall contamination levels in the waste at the Olympic site are within exempt levels. The waste has been correctly disposed of and no rules, or laws, have been broken.'

The ODA strongly believes that the best policy against waste is to get its attack in first. Its 'Learning Legacy' has been reviewing progress. 'Waste typically adds 1-3 per cent to construction costs. However, a saving of 30 per cent or more can be achieved by adopting good practice to reduce the amount spent on materials and the cost of waste disposal. For most projects, the largest savings will be uncovered during the design stage by making decisions which optimise the use of materials and reduce the amount of waste. This is 'designing out waste'.'

The Olympic Stadium, for example, has the potential to be downsized from 80,000 to 25,000 seats after the Games to provide a more appropriately-sized stadium in legacy. All steel used was bolted rather than welded, which makes it easier to take apart.

Much of the accommodation and facilities required, including hospitality suites, toilets, catering and retail facilities, are stand-alone units that may be reused or recycled after the Games with minimal disruption to the venue. The lower tiers of the Olympic Stadium have been constructed in a sunken bowl, thereby reducing the overall height of the Stadium and the amount of structural materials (steel and reinforced concrete) required, resulting in a more resource-efficient outcome. Creating this bowl during the enabling works, rather than the main construction phase, saved the excavation of over 100,000m3 of soil and £3m in earthworks costs. Standard lengths of surplus gas pipeline were incorporated into the design for the compression truss structure that forms the upper section of the stadium. Reusing this waste material from the gas industry saved 2,500t of new structural steel.

Building the Park

The Aquatics Centre has been designed as a permanent structure with two temporary seating 'wings' that will be removed after the Games. Reuse of 104,000t of recycled crushed concrete (previously brought to site for the temporary piling platform) meant that there was no need to import virgin aggregate for the permanent works, saving £1m and more than 20,000 lorry movements.

Industry price books assume a wastage rate for metal profiled cladding of 5 per cent. Only 2 per cent wastage was achieved in cladding the roof (28,600m2) and east elevation (5,200m2) of the International Broadcast Centre by having the cladding supplied in coils, which were cut and formed to the precise length and profile on-site, so off-cuts were largely eliminated. The 14t of waste was mainly coil ends, and a take-back scheme was agreed with the manufacturer.

Waste water and sewage

A pumping station has been built to recycle and clean water, and to provide 570,000l of non-drinkable water for the Olympic Park. Waste water is drawn from the Northern Outfall Sewer designed in the 1800s by Sir Joseph Bazalgette, whose revolutionary sewer network stopped the River Thames from being an open sewer. It is then treated with screening, membrane filtration and colour-removal processes to achieve the required standard. The recycled water is delivered to the Park outlets via a recycled water network. It will be used to flush more than 80,000 toilets each day, for rainwater harvesting, and for irrigating the parklands and the fields of play within venues. It will also cool and heat the Energy Centre.

As for sewage from the Park, that gravitates to the adjacent Deep Foul Sewer and all flows from this are returned to the Northern Outfall Sewer downstream from the recycled water plant.

Following the prevention rather than cure policy, there are a myriad of water efficient installations; low-flow taps, low-flush toilets, and waterless urinals to reduce water demand. The Olympic Village is also being designed for water consumption of 105l against a standard of 160l per person per day.

Time for the Games

During the Games, the Park people need to meet the demands of waste products and rubbish from thousands of people every day. This is a work-in-progress, so plans are being made in the hope they will be carried out satisfactorily on the day. It will be impossible to achieve zero waste at this stage, but there is a promise that the amount of waste produced will be minimised. Landfill is not on the agenda – no waste will be sent directly to landfill.

All sorts of waste should be seen as a potential resource and at least 70 per cent of it reused in some way. Detailed studies indicate that about 8,250t of operational waste will be generated, with around 60 per cent originating in the Olympic Park. In addition, about 40 per cent of waste will be food or food-contaminated packaging.

Attempts were made to reach agreements with suppliers for a 'single-material approach' for bottles and other packaging items; also to arrange a simple system for waste and recycling collection, and get spectators on-board by designing a simple icon and colour-based disposal scheme. Research undertaken by ALCOA, the aluminium giant, shows that by recycling 1,000kg of aluminium cans about 5,000kg of bauxite is stopped from being mined.

Games legacy

After the Games, the park reverts to a building site once more; the five main stadiums will be downsized and the Village converted to flats and homes. Problems will arise similar to those that confronted the staff at the beginning ' a site with buildings that have to be decommissioned, at best, and demolished if necessary.

The challenge is two-fold: first, the immediate recovery and redistribution of assets (such as equipment, furniture and other useful materials). This is, the Olympic Park Legacy Committee admits, a concern because the dismantling of structures after events is typically rushed and there is a lot of wastage. 'Waste stream separation,' it acknowledges, 'at this stage is rare.' Secondly, the disassembly rather than demolition of major temporary structures such as wings of the Aquatics Centre.

The winning of the World Athletics Championships has ensured the future of the Olympic Stadium for several more years as an athletics venue, and West Ham Football Club has not ruled out taking it over as a football stadium. Barr Construction, owners of the Basketball Stadium, say there is a possibility that it will be used in the 2016 Olympics in Rio. The Village has already been sold for private and affordable housing after the Games, while the search continues for buyers of seats and fittings and – useful waste. *

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