Not so long ago around a third of all waste going to landfill originated from construction and demolition sites, according to official estimates. But in the past couple of decades, recycling and re-use has reduced this contribution massively. Current figures show that the UK recycles more of its construction and demolition (C&D) waste than most other EU countries. Some projects have recorded landfill diversion rates of more than 90% while the overall average rate in 2012 was a respectable 66.4%. That average rate is predicted to increase to 75.5% by 2020. An optimistic estimate, maybe, but still in line with the Waste Framework Directive which set a 2020 recycling rate target of 70% (by weight) for re-use, recycling and other recovery of C&D waste. Whether that target is achieved or not depends upon the industry raising its game – or turning to specialists such O’Donovan Waste Disposal, one of a growing number of waste management firms that started out as demolition contractors.

London-based O’Donovan was founded in the late 1950s by Joe O’Donovan and is now headed by his daughter, Jacqueline, who is qualified as a chartered waste manager by the Chartered Institute of Waste Management. Over the past 10 years or more, legislation and changes in best practice have resulted in conscientious contractors installing colourcoded skips for on-site waste segregation – one for timber, one for plasterboard, another for masonry and so on. But in O’Donovan’s view, contractors are often mistaken in favouring on-site waste segregation.

“Some customers like the idea of having waste sorted on site – and it does give the appearance that they’re taking recycling and sustainability seriously,” she says. “But there are some very strong and compelling reasons why they should leave waste segregation to a waste management partner like us rather than entrust that to someone who might just want to get on with their own job, whether that’s drylining or laying bricks.”

O’Donovan points out that companies such as hers have the experience and the specialist equipment to carry out the task, with staff that are trained and qualified to identify, sort and recycle waste. This is more efficient, she says, because to do it on site requires staff to be trained and diverts them from their main construction tasks.

Consequently, O’Donovan segregates 85% of its clients’ waste and only 15% of them choose to do it themselves on site. The company takes its clients’ concrete and masonry waste to its dedicated two-acre recycling plant in Tottenham, where it is crushed and screened for re-use. Scale is important here, argues O’Donovan, because a client might consider the quantities from a specific site too small to recycle. “But we, on the other hand, will have a sorting bay for that specific waste stream so we’ll segregate whether we have one or 21 skips of material.”

Engaging a specialist contractor to handle all waste also minimises journeys and saves space – which can be a major consideration on the tight sites that are typical in London. “There is only one skip or bin instead of several and there are fewer journeys to site saving fuel and reducing emissions because we don’t have to collect any containers that are not full to capacity,” says O’Donovan. “And we can offer a ‘wait and load’ option so that there are no skips left on site – the lorry turns up and is filled there and then.”

Employing a specialist also allows the client to demonstrate its recycling credentials; O’Donovan issues a report detailing exactly what went where and what proportion did indeed end up in landfill. This can be presented on whatever basis suits the client – some might want the recycling statistics on each individual project while others prefer a monthly summary of their activities across several sites.

Before the WRAP Quality Protocol (see box) came in there was little or no regulation in the recycled aggregate industry, says O’Donovan, so some companies were “not always very attentive with regards to the quality and knowledge of what they were actually processing”. The WRAP protocol enables clients to audit suppliers to ensure compliance, resulting in a superior quality of recycled aggregate. This encourages both architects and surveyors to use recycled material rather than virgin aggregate, so making projects more sustainable.

An audit trail of the materials that come out of the construction site is also an important component of environmental assessment schemes such as RICS’ SKA scheme for office fit-outs and BRE’s BREEAM methodology. Waste management companies that provide clients with waste reports that show recycling levels of 90% and above, complete with a detailed breakdown of all the materials, can make a significant contribution to improving the rating that is awarded to a building, as Paul Tinton of Prowaste, another waste management specialist, points out.

There are two strong reasons to encourage continued growth in the use of recycled aggregates: the supply of virgin aggregates is limited; and the capacity of existing landfill sites is shrinking. The UK aggregates industry produces around 210 million tonnes of crushed rock, sand and gravel per year for construction use from over 1,500 quarries. But with current extraction rates of sand and gravel depleted by about 50%, there is no guarantee that production could match any hike in demand. 

Partners in grime

Prowaste is a waste haulier and broker that has worked with O’Donovan Waste Disposal for eight years, describing it as the ‘go-to company for North London’. “Its recycling rates are phenomenal – way over 90%,” says director Paul Tinton. “It’s also important to the contractors who are our clients that this is documented, together with the breakdown of materials into the various waste streams, because these reports contribute to sustainability assessment schemes like BREEAM and SKA. They can then use these in tender documents to show that they have sustainable working practices and recycle materials.

“London is congested and floor space on site is restricted so in these circumstance it is correct to say that it is best to have simply one skip on site as it wouldn’t be costeffective to have, say, five skips for five different types of waste. Off-site waste segregation is the best option here. “There’s also the issue of transport, where using the one skip or container will minimize journey times.”

No space for skips

Geobond and Abtech Basements are two sides of the one business, one being the piling contractor while the other installs basements. Both use O’Donovan Waste Disposal to remove the spoil, which is a mixture of soil, hardcore, timber and general builders’ rubble.

“The sites we work in don’t have room for more than one skip – if that,” says director David Hilton. “And it wouldn’t be worthwhile in terms of transport and congestion either to have separate skips for segregating waste. “Our staff are better employed carrying out their trades, not sorting out waste.

There are several ways in which you can segregate waste so they could make a mistake whereas the sorters at O’Donovan do it all day.

“We find the company’s documentation very useful because we’re part of the Considerate Contractor’s Group and that requires us to document what happens to our waste and how much is recycled. With O’Donovan we can just use its figures.”

It’s a WRAP

In 2004 the Defra-funded charity WRAP (Waste & Resources Action Programme) published a Quality Protocol for the production of aggregates from inert waste, formulated in partnership with the industry.

This protocol helps ensure that recycled aggregate conforms to the appropriate European Standard and encourages its wider use by providing recycled aggregate suppliers with:

• a procedure to control the quality of recycled aggregates for sale as construction materials, or as constituents in a product, e.g. concrete, asphalt and unbound mixtures

• recommended minimum frequencies of inspection and testing conforming to the requirements of the European Standards for aggregates

• the means for suppliers to provide adequate assurance that their products conform to relevant technical specifications and certified characteristics. As a result, the construction industry can use recycled aggregates with confidence, knowing that they have been subject to a rigorous regime of inspection and quality assurance.

This article first appeared in the April 2015 issue of The Construction Index magazine. To read the full magazine online, click here.

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