From brownfields to gold medals

17th January 2012


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From remediation to biodiversity - Lucie Ponting investigates how London 2012 is measuring up to its sustainability goals

Seven years ago, the London 2012 bid team promised the International Olympic Committee it would deliver the “first sustainable games”. By this, it meant embedding sustainability at every stage of the games, from planning and venue construction, through to the events themselves and on to the legacy for local communities and the rest of the UK.

To achieve this ambitious goal, the London 2012 sustainability plan − launched in 2007 and revised in 2009 − outlines a clear vision for the revitalisation and regeneration of one of the most deprived parts of the country. It also incorporates targets covering everything from low-carbon strategies and waste to biodiversity and healthy living.

The first phase covered by the plan − “building the stage” − focuses on the design and build of the Olympic Park, other permanent venues and the supporting infrastructure, including an energy centre providing low-carbon power. This work involved not only construction of such high-profile venues as the Olympic Stadium and Aquatics Centre, but also the earlier site planning, remediation and demolition work.

For the Olympic Delivery Authority (ODA), which is responsible for the build, the brief was hugely challenging – a project twice the size of Heathrow Terminal 5 to be completed in half the time on what was a highly contaminated brownfield site, blighted by fly-tipping and poor water quality. But by July 2011, the ODA announced it had completed all the “big build” venues on time and on budget, and had met, or was on track to meet, most of its sustainability targets.

In this first phase, the project has already racked up some impressive statistics, including recycling and reusing 98.5% of the demolition material on the park, cleaning and reusing 80% of previously contaminated soil on the site, and transporting 63% (by weight) of construction materials to the park by rail or water.

Not another target

From the outset, the ODA’s strategy set out stringent sustainability targets (mirroring the sustainability plan) in 12 key areas, including carbon, water, waste, biodiversity and transport. To verify these on the ground, the authority and its partner CLM have monitored performance internally, and the independent Commission for a Sustainable London (CSL) is providing external audit.

As the client, the ODA required all the park’s principal contractors to have a fully approved environment management plan, setting out how potential environmental effects of the works would be managed and project targets met.

“[We] set the pace and everybody then followed that because it was embedded in contracts,” explains the ODA’s director of infrastructure and utilities, Simon Wright. The designers had the targets in the brief against which they bid, adopting those into their designs. The same standards then went in contractors’ tender documents. “So all the way through,” he stresses, “no one was in any doubt about what we were trying to achieve, and then they themselves were held accountable for delivering their components of it.”

Kirsten Henson, director of KLH Sustainability, who was part of the CLM sustainability team on the park, found that one of the biggest challenges was breaking down some of the entrenched views and barriers put up by designers, engineers and contractors who were used to doing things in a certain way.

“I was constantly surprised by the level of reluctance to do something differently,” she says. The consulting engineers, in particular, tended to be very conservative and risk averse.

“But the most interesting thing,” she adds, “is that once people started [getting involved in] sustainability and thinking differently, they got really quite excited about it.” Over two or three years, she watched people such as design managers with 30-plus years’ experience change their whole perspective and be thrilled that there was now a new dimension to their job.

She believes – and this was reinforced by her Olympic Park experience – that to engage people effectively, it’s crucial they understand what they’re doing in terms of sustainability, and why. Otherwise, the reaction is often: “Oh no, not yet another target.”

“On the park, we [the ODA and CLM] didn’t simply say: ‘We want this and that … so go and tick the boxes.’ People came to us for guidance, advice, ideas, information and support if they were trying to get certain things through, or if they were struggling,” says Henson. “A lot of clients don’t tend to offer that; they say: ‘Yes, we want it’, but don’t check, don’t provide guidance and don’t provide support.”

Dig, demolish, design

The ODA’s first task was to prepare the 245-hectare park site in the Lower Lea Valley. With a higher budget than any of the individual venues, the enabling and remediation works involved clearing and cleaning the derelict site, the removal of 52 overhead power pylons, rerouting power cables into two 6km tunnels under the park, and providing new water and power networks.

Industrial contamination on-site included oil, petrol, tar, cyanide, arsenic and lead, as well as some very low-level radioactive material. Overall, there were almost 3,000 soil investigations into contamination, and a special “soil hospital” set up in the park that washed, sieved and shook the soil free from contaminants. In total, more than 80% of 800,000 cubic metres of contaminated soil was cleaned and reused on-site through soil washing and large-scale composting.

Alongside the soil work, the project treated more than 20 million gallons of contaminated groundwater using innovative techniques such as injecting compounds into the ground, and generating oxygen to break down harmful chemicals.

Contractors also had to treat and clear about four hectares of invasive Japanese knotweed, which can cause serious damage to infrastructure. Treatment techniques included in situ spraying with persistent or non-persistent herbicides, excavation under the supervision of specialist contractors, screening of excavated material, controlled incineration of knotweed cane, crown and rhizome material, and deep burial using proprietary root barriers.

In all, more than 215 buildings were demolished, as well as a number of walls, bridges and roads. The target for 90% (by weight) reuse or recycling of demolition material was exceeded, reaching 98.5% on the park. Although reuse of materials is more desirable than recycling – leading to greater reduction in waste to landfill and greater savings in carbon emissions – the general target of 90% did not include a specific target for reuse.

In practice, there were high levels of recycling, and negligible levels of reclamation for reuse (an estimated 0.5%). Some of the materials reclaimed and stored for reuse were 660 tonnes of various brick types, 176 tonnes of paving material and 5,400m of kerbing.

“The reuse side of things was challenging,” remarks Henson. “Though there was definitely a commitment to reuse, in the end the users weren’t there. The industry was a bit behind in terms of there being a market for reused products.”

Based on this experience, the ODA suggests clients in future set a specific reuse target, rather than just a combined figure. Other recommendations include appointing specialist reuse/salvage contractors during the pre-demolition and demolition stages, carrying out detailed reclamation surveys, and establishing a storage area for reclaimed materials on or near site.

Big build

Alongside the 90% demolition waste target, the other construction waste targets included: using 25% (by weight) of recycled and/or secondary aggregate for the construction of venues and park-wide infrastructure; 20%, by value, of construction materials from a reused or recycled source; and a waste management contractor committed to diverting 90% of construction waste from landfill through reuse, recycling and recovery.

To achieve these, the ODA’s construction waste management plan (CWMP) implemented a centralised waste management service with an on-site waste consolidation centre, and required every tier 1 building contractor to produce its own CWMP. In April 2011, the ODA reported that all the key targets for waste were “on track”, with the foundations for the Aquatics Centre, Handball Arena and the Olympic Stadium using concrete with more than 30% recycled materials, and at least 20% of the precast concrete units for seating terraces, temporary bridge decks and the Handball Arena created from recycled aggregate.

The built-in design features of the venues, and the associated infrastructure, such as a non-potable water system and the energy centre (which includes a combined cooling, heating and power plant), will help to ensure that London 2012 meets its sustainability commitments in phases two and three of the sustainability plan – staging and legacy.

Specific carbon targets include:

  • each permanent venue to aim to achieve a 15% carbon dioxide reduction above Building Regulations 2006 (BR2006) Part L;
  • the Olympic Village to be 25% more energy efficient than BR2006 requirements, meeting level 4 of the code for sustainable homes;
  • permanent venues to achieve a BREEAM “excellent” rating in legacy (as BREEAM has never been used on major sporting venues, a bespoke rating had to be created for London 2012);
  • 20% of all energy demands for post-games legacy to be derived from on-site renewable sources; and
  • an aspiration to reduce the overall carbon emissions associated with the built environment in the Olympic Park development by 50% by 2013.

With the exception of the 20% renewables target, London 2012 is currently on track to meet all of these goals. “All the sustainability targets … have proven pretty tough to achieve,” says Wright. “We deliberately set out to stretch ourselves, and the industry, so we were expecting them to be hard. But overall, we’ve been successful in delivering most of them.”

Winning the race

Carbon reduction has proved one of the greatest challenges. In 2010, the ODA scrapped a planned wind turbine, dubbed the Angel of Leyton, after the preferred bidder’s turbine supplier pulled out.

“We didn’t get the wind turbine in the end,” explains Wright, “so we didn’t get the proportion of renewables we wanted, but we did recover our position on overall carbon emissions; we adapted and re-evaluated to meet the target of 50% reduction in emissions.” This will now be through a 9% contribution from on-site renewable energy, rather than the original 20%.

Another key challenge was getting the sustainable concrete mixes and workability right. Given the high environmental impact of concrete, improving its sustainability was crucial. “To get the finish right on concrete with a high recycled-waste content has been quite tough,” says Wright. “It’s a different kind of mix to what most of the contractors and supply chain were used to, so we needed quite a lot of work; that was hard work at the time but successful ultimately.”

Overall, the development of more environmentally-friendly concrete mixes resulted in the use of about 170,000 tonnes (almost 22%) of recycled and secondary aggregate, a saving of approximately 30,000 tonnes (24%) of embodied carbon, and the elimination of more than 70,000 road-vehicle movements. Rationalisation and efficiency of design reduced total concrete demand by 65,000 cubic metres, saving a further 120,000 tonnes of aggregate and 20,000 tonnes of embodied carbon.

The latest annual report from CSL, published in April 2011, concludes that the ODA has “done an exemplary job of sustainable construction” and “set new standards that the industry would be well advised to follow”. To capitalise on its experience, the authority has established a learning legacy programme, which includes sustainability as one of its 10 themes.

“The intention is to provide a library of information, details and lessons learned,” explains Wright. “It’s not a formula or a silver bullet; it’s there to give other projects an opportunity to gain an insight into what went on in the Olympic programme and to provide them with maybe a bit of a head start … so they can short circuit to successful outcomes in their own way.”

Henson says the sheer scale of the Olympic work is what makes it different; other than that, the actual processes are identical, whatever the project. “The solutions might be different, the innovations might be different, but the challenges you face, the way the project is structured, and the approaches you need to take are going to be very similar.


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