July 2012 » environmentalistonline.com

CONSTRUCTION 7

The big build

In July 2011, a year before the 2012 opening ceremony, the ODA announced it had completed the five main venues – a phase known as the “big build” – on time and on budget, and had met, or

was on track to meet its sustainability targets.The construction phase not only incorporated the

design and build of such high-profile venues as the Olympic stadium, the velodrome and the aquatics centre, but also all the supporting infrastructure, including an onsite energy centre providing low-carbon power.

Built-in design features for the venues and the associated infrastructure, such as a non-potable water system, and the energy centre, will help London 2012 meet its sustainability commitments in phases two and three of the project – staging and legacy.

Being responsibleResponsible sourcing of building materials was a key ODA priority. One of its flagship objectives was to use only timber from known legal sources and maximise the use of timber from sustainable sources.

Procuring timber from illegal or uncertified sources presented a very high reputational risk, so only certified timber with a full chain of custody, from forest to end-user, was used. The ODA put in place rigorous processes to ensure that all contractors and subcontractors complied. The main mechanism for this was a timber supplier panel, which acted as a site-wide supply framework. This panel involved 16 suppliers, all of which could guarantee that the timber supplied would be 100% legal and certified as coming from sustainably managed forests. “The panel moved some of the risk away from the buyer and shifted it onto the panel,” says Noah Bold, sustainability manager CLM (see p.9), the ODA’s delivery partner. “A lot of panel members were already key suppliers to many of the contractors, and companies wanted to be part of it.”

All the projects had to order their timber – for anything from temporary formwork or hoardings to the Siberian pine for the velodrome track – from the panel, and an online delivery booking system helped facilitate this. It also sent an email alert to the sustainability team whenever a contractor ordered a timber item. When timber arrived onsite, it was checked for certification through a rigorous auditing procedure. “We had a small army of timber ‘champions’ checking and verifying deliveries,” says Bold.

The outcome of all this work is a world first for the Olympic park, which in

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July 2012 » environmentalistonline.com

CONSTRUCTION 9

embodied carbon. The majority of projects poured piling and foundations using concrete with at least 50% coarse aggregate substitution, rising to 76% for the aquatics centre.

Using the existing railhead infrastructure at Bow East for importing bulk loose construction materials removed an estimated 80,000 lorry movements. The Bow East Logistics Centre could process 32 trains a week; and each train could carry around 1,350 tonnes of aggregates. Overall, 4 million tonnes of goods will have been moved by rail by the start of the games, saving 120,000 tonnes of carbon dioxide in comparison with an equivalent delivery operation by road transport.

Waste notTo achieve the ODA’s key construction waste targets – including diverting 90% of waste from landfill – it implemented a comprehensive construction waste management plan. This incorporated a centralised waste management service with an onsite waste consolidation centre (WCC), while every tier-one contractor working on the park had to produce its own site waste management plan.

In August 2008, after Veolia Environmental Services was awarded the park’s waste management contract, the ODA required all contractors to use it for waste management. This tightly controlled, centralised approach was fundamental in managing waste effectively and achieving economies of scale. “To manage our duty of care and reduce transport movements, we had to have a framework,” says Bold. “We couldn’t have hundreds of different skip firms driving around the park; we just couldn’t have monitored it coherently.”

Waste highlights on the park include: n approximately 2,000 tonnes of waste removed from

the site by barge;

March 2012 became the first construction project to secure certification from both the FSC (Forest Stewardship Council) and the PEFC (Programme for the Endorsement of Forest Certification), with 100% of wood products supplied certified as “legal and sustainable”. FSC-certified material made up 67% of the 12,500m³ timber products procured, while PEFC accounted for 33%. The athletes’ village project had achieved FSC certification a few months earlier.

All in the concrete mixGiven the high environmental impact of concrete, improving its sustainability, together with getting the right finish on concrete with a high-recycled content was a key focus.

The tight construction timeframe, combined with the need for a reliable supply with high sustainability credentials, led to the procurement of an onsite ready-mix concrete batching plant, which provided concrete to all the park projects.

Overall, the development of sustainable concrete mixes resulted in the use of around 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.

“One of the biggest challenges we faced early on was to gain the acceptance from the designers and architects for using fair-faced concrete with a high recycled content. This was because the finished colour often varies, due to the various products being used,” explains Darren White, then environment and sustainability assurance manager at CLM (see p.15).

Rationalisation and efficiency of design reduced total concrete demand by 65,000m3, saving a further 120,000 tonnes of aggregate and 20,000 tonnes of

Sustainability manager, CLMSustainability manager Noah Bold was first employed at the Olympic site in 2008 as a waste and materials manager. Later, he was in charge of implementing the environment and sustainability management plan for park operations, while retaining his waste and materials management responsibilities. As a result, his role spanned the supply chain, including timber, waste, concrete and aggregate, as well as the movement of people and transport across the Olympic park

One of the key achievements during his four years at the London 2012 site was managing the supply and certification process for timber, which included bringing together the FSC (Forest Stewardship Council) and PEFC (Programme for the Endorsement of Forest Certification) to certify the same project. “Not only is London 2012 the largest construction site in the world to achieve certification, but it was also the first to achieve joint FSC/PEFC certification,” he notes.

Another innovation at the Olympic park was the creation of the timber supplier panel, a group of timber suppliers that all contractors were required to use. Bold managed the supply of more than 12,500m3 of legal and sustainable timber through the panel. He was also involved in researching and implementing some of the ODA’s policies on materials, including timber and PVC.

For the waste element of his role, Bold was responsible for the management of the Olympic park framework for waste contractors’ performance against the site’s reuse and recycling targets. This included monthly reporting, site waste-management plan reviews and the development of reuse strategies. During construction, more than 20 tier-one contractors and hundreds of subcontractors all produced waste, but more than 90% by weight was diverted from landfill. Bold points out that the waste-management standards reached at the Olympic park exceeded current industry best practice.

“This project embraced the sustainability agenda from the outset, and the successes achieved were in no small part due to the bedrock of sustainability the project was built on”, says Bold.

Prior to joining CLM, the ODA’s delivery partner, Bold was an environment adviser at Costain, working on the Thames Water framework. He is a sustainability manager at Laing O’Rourke, although he has been seconded to LOCOG – the games’ organising body – and will be working at the park throughout the Olympic and Paralympic games. He is a London 2012 learning legacy ambassador and has presented at several high-profile events, including Ecobuild. Bold is an AIEMA and an IEMA-approved advanced environment management systems assessor.

NoAh BoLd

Environment adviser, Skanska UKSkanska Civil Engineering was the main contractor for the construction of structures, bridges and highways in the north of the Olympic park. Richard Hirst, then environment adviser with responsibility for community relations, worked for Skanska at the park for two years, between 2009 and 2011.

As environment adviser, Hirst was involved in several innovations at the site that saved significant sums of money and which are likely to be replicated on other construction projects. One was trialling the use of biodiesel in Skanska’s fleet of vehicles. A big barrier to using biodiesel is how to get around the risk of it voiding vehicle warranties. “We used sustainably sourced waste rapeseed oil made to a European specification for biodiesel and we took on board the risk of the warranties being voided,” explains Hirst. The company switched to a B50 blend of biodiesel in all 12 roadworthy vehicles used on the project, although it did not use it in plant machinery. “We made an average 12% cost saving,” says Hirst, “and didn’t damage any vehicles.”

A key challenge for Skanska was to manage the large volumes of ground and surface water it encountered during the London 2012 works. This was a compliance issue in terms of dealing with discharge consents, but also opened up an opportunity for water reuse. Hirst set up a water treatment area to treat and test the water, which was then pumped to discharge pumps. At the same time, Hirst explains, contractors were queuing up at the hydrant to get drinking quality water to use for dust suppression. “So we got a couple of containers, tested the water to ensure it met required parameters, and then harvested it, eventually reusing over 10 million litres of non-potable water for dust suppression.” In financial terms, it saved £75,000.

Hirst is now sustainability manager at Skanska UK.

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Skanska Civil Engineering met or exceeded all the ODA’s environment and sustainability targets, leading to several ODA awards, including sustainability team of the year and a prize for near-miss reporting.

“The ODA’s sustainability agenda was really clear,” says Richard Hirst, environment adviser for Skanska on the project. “The client was committed, and its communications, guidance and scrutiny were consistent all the way through.” Among Skanska’s exceeded targets were: 99% of key materials responsibly sourced (against the 80% target); materials’ recycled content by value of 47% (target 20%); and use of “healthy” materials (non-poluuting/non-toxic) 99% (80% target).

“The ODA also sent out a clear message about culture and engagement,” adds Hirst. “We had over 300% more near-miss reports than anyone else, and we saw that as a really good thing. Most people wouldn’t even know what an environmental near-miss is, so the fact we had so many showed a really high level of understanding onsite, and that came from creating a culture of sustainability. It’s the switch in the way people think that makes a difference.” In one case, a worker handed in an environmental near-miss asking why, once the site roads were covered with tarmac, everyone was still driving around in 4X4 vehicles. “We took it to the commercial director,” says Hirst, “and the next week we got rid of the 4X4s we didn’t need, which improved fuel efficiency.”

To help embed site-level buy-in, Skanska also ran monthly sustainability meetings. “Instead of environment and sustainability being one of the last agenda items in the project meeting, we had a dedicated sustainability meeting involving the project, commercial and construction managers, foreman, works manager and environment champions,” says Hirst. The company also held environment weeks, included masterclasses, and every month hosted two “foreman’s toolbox” talks focused on the environment, putting it on a par with health and safety.

A CoNtRACtoR’S PERSPECtIVE

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n several projects achieving levels of segregation at source of more than 90%, with the overall park figure for construction waste diverted from landfill reaching 99.1%; and

n development and implementation of a reuse strategy, with the support of the Environment Agency, whereby surplus materials could be either reused by other contractors or given free of charge to local community groups.

By consolidating and compacting waste at the WCC, crushing and reusing concrete onsite, and using barges to remove certain waste streams, the park managed to reduce offsite vehicle movements by around 90%. To allow use of the waterways, the ODA built a wharf onsite and completed a multimillion pound dredging programme to give 350-tonne barges park access.

driving down embodied carbonThe design of venues at the Olympic park has sought to reduce their embodied carbon, primarily through lean construction and by designing out waste through a process developed by WRAP.

The main roof truss at Olympic stadium, for example, consists of 2,600 tonnes of surplus gas pipes, reducing its embodied carbon by avoiding the manufacture of new steel. The “cablenet” roof on the velodrome weighs 30kg/m2, which is less than half the weight of the cycling venue at the Beijing Olympics, and, compared with the original steel arch design, uses around 1,000 tonnes less steel, resulting in embodied carbon savings of more than 27%. Overall, a combination of design optimisation, recycled aggregate and average cement substitution of 32%, reduced embodied carbon across the Olympic park by more than 85,000 tonnes.

Responsible sourcingThe copper box (formerly known as the handball arena) is clad in vertical standing seam copper. The ODA demands that all materials are from responsible sources, and suppliers have to provide evidence of the existence of legal sourcing. Also, as a permanent venue the copper box had to adhere to BREEAM standards, one of which, responsible sourcing of materials (MW8), requires venues to demonstrate that 80% of building materials are responsibly sourced.

A German company supplied the copper cladding – which is made from 35% new copper (primary) and 65% recycled. The primary copper was sourced from a mine in Chile. The mining and mineral-processing operations of the mine is certified to ISO 14001 and has a corporate responsibility policy. The recycled copper came from the cladding supplier’s own production scraps as well as copper scraps from recycling companies in Germany. To ensure responsible sourcing, the copper for the park was given its own batch number – Olympic 50010265. As it was processed, this number was stamped along the edge of the copper coils to show origin. The cladding was fabricated onsite at the Olympic park. The small amount of copper left over from the building was passed to the ODA’s artist in residence for incorporation into an artistic installation.

Non-potable water for the buildConstruction sites use significant amounts of water to control dust and mud on roads. Non-potable water supplies are preferable to potable mains supply – available through the hydrant network – in such circumstances because it is less costly and more sustainable.

The ODA installed a number of groundwater abstraction boreholes at the Olympic park to provide non-potable water supply for construction use. The financial savings were clear: non-potable water from the borehole cost £0.24 per cubic metre, while the cost of potable water was £1.13/m3. The ODA reports that it broke even when contractors had used 225,000m3 of non-potable water – that is, around 40% of the licensed amount over three years – which was achieved in the first year of operation.

A limit was also placed the amount of potable water the contractors could access. Thames Water, which operated the

hydrant network, issued licenses allowing the holder to draw a maximum of 20m3 a day from any one of the water company’s hydrants. The overall number of hydrants was also reduced.

Plant-based walkways During the Olympic and Paralympic games, the park concourse will cover more than 18 hectares. Manufacturers and contractors were invited to demonstrate innovative surfacing solutions. Following trials, the ODA opted for an entirely plant-based alternative to bitumen and petroleum resin-based binders for binding the gravel areas.

The plant-based emulsion, called Vegecol, has significant environmental benefits over traditional hydrocarbon-based binders, including reduced CO2 emissions from its manufacture, and less risk of pollution as there is no leaching of contaminants into watercourses. The ODA also instructed contractors to avoid using traditional hot-mix asphalt where possible. Instead, they used a cold-lay surfacing material, which has a 94% recycled content and uses 5% of the energy consumption of traditional materials.

Noise controlContractors had to adhere to a code of construction practice during the building of the park. This was a contractual commitment to keep within set parameters for noise, dust and out-of-hours working. Contractors were asked to eliminate noise where possible, through either careful planning of the construction activity or offsite pre-fabrication of materials. Where this was not possible, they were required to reduce noise to an acceptable level by using so-called best practicable means (BPM). Examples of BPM being applied onsite include: hydraulic pile croppers to remove pile caps instead of pneumatic breakers; and vibration and auger piling, or vibro-piling, instead of the traditional percussion piling.

Noise levels were constantly monitored throughout the project, with each contractor and local authority (Hackney, Newham, Tower Hamlets and Waltham Forest) receiving a weekly RAG – red, amber, green – report.

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