Monitoring Recycled And Secondary Aggregate Useage

The Government’s approach to the collection of information on alternative sources of aggregates

It is government policy to encourage the use of secondary and recycled materials in construction and the Government is committed to increasing significantly the level of use. This clear and unambiguous statement of policy is contained in MPG6, published in April 1994, and successive ministers have reaffirmed it. MPG6 set targets for the use of secondary/recycled materials in England which were reflected in the guidelines for aggregates provision. It was noted that an improved statistical base would be required for monitoring these targets, and that arrangements would need to be put in place for this.

Accordingly, in September 1996, Arup Economics & Planning were commissioned to identify and test a system for collecting the information needed to monitor the policy. The research was guided by a steering group which included representatives from the Environment Agency, Highways Agency, Quarry Products Association, CSS (formerly County Surveyors’ Society), Civil Engineering Contractors’ Association, National Federation of Demolition Contractors, Planning Officers’ Society and the Regional Aggregates Working Parties (RAWPs). Their contribution proved invaluable. Each body represented has a role in the collection of the required statistics and the steering group members helped greatly in identifying and testing the recommended system and, where appropriate, recommending participation in surveys of member companies.

At an early stage in the research it became clear that the materials could be divided into three categories in terms of data collection:

• construction and demolition (C&D) waste
• materials for which statistics seemed at the time to be ‘easier to collect’
• asphalt road planings.

In their report, Arup1 recommended an approach related to these categories, and since 1998 the Government has been seeking to implement this approach, amending it in the light of experience and changed circumstances. The aim is to collect the following information for each relevant material:

• the amount of each material arising (and, where appropriate, the amount stockpiled)
• the amount used as aggregate
• the scope for further use as aggregate.

Construction and demolition waste

For C&D waste the recommended approach was to build upon existing Environment Agency (EA) obligations to monitor licensed waste-management sites and also to seek ways of separately monitoring the increasingly significant mobile crushing sector. The report concluded that all three industry sectors — crushers, licensed sites and exempt sites — would need to be covered if comprehensive C&D waste statistics were to be obtained. In summary:

• crushers are important because C&D waste processed for use as aggregate is crushed (and/or ??screened).
• material is used as aggregate on licensed landfill sites for landfill engineering work, such as site roads, and some material with potential for use as aggregate may be disposed of in these locations.
• large amounts of material which may have potential for use as aggregate go to sites exempt under paragraphs 9 and 19 of the waste regulations.

The advice was followed for a survey of C&D waste in 1999 in England and Wales, undertaken by Symonds Group Ltd for the EA and co-funded by DETR with the support of the National Assembly of Wales. Although the national results were reasonably reliable, the confidence limits for the regional results were extremely wide. The same consultants are now carrying out a survey of authorized crushers, landfill and exempt sites in England and Wales for 2001. The survey builds on, and improves, the methods used for the 1999 survey. The aim is to get more reliable results for each RAWP region as well as nationally, although the regional figures will still be less reliable than the national figures and the reliability of both will depend on the survey response rates. The results are expected to be available by autumn 2002.

‘Easier-to-collect’ materials

This category includes:

• blast-furnace slag
• basic oxygen steel slag
• electric-arc furnace steel slag
• china clay waste
• colliery spoil
• coastal dredgings
• power station fly ash
• power station furnace bottom ash
• spent railway track ballast
• slate waste
• waste glass
• MSW incinerator bottom ash
• scrap tyres
• fired ceramic waste
• spent foundry sand.

The method proposed for collecting statistics for these materials was considered to be straightforward when Arup reported in April 1998. The main constraint to obtaining more comprehensive statistical data was identified as the lack of accurate contact data for producers. It was recommended that the secretaries of the RAWPs should build upon and maintain a national list of producers (prepared by the consultants) and use it for their future annual surveys and reports.

Radical changes in industrial structures and processes in recent years have made the task more difficult. Some RAWPs have been able to provide reliable data in their annual reports, while others have found it difficult to collect all the relevant information in a systematic manner. In order to help, Symonds Group has been commissioned to collect data on the arisings, stockpiles and use of these materials in 2001. This study should indicate where there is a failing to account for material and should also provide a basis for improving the current work of the RAWPs by providing up-to-date information on sources and contacts. The final report will be published this autumn.

Asphalt road planings

The proposed method for collecting statistics was limited to data from planned maintenance planing. Because local and trunk road/motorways are managed separately, the proposed Arup approach involved a two-step process, first for the roads for which local highways authorities are responsible, and secondly for the trunk road/motorway network for which the Highways Agency is responsible. Asphalt arisings from ‘streetworks’ repairs etc would be covered by the C&D surveys.

For local highway authority roads the proposed approach was to seek information from county (and unitary) highway authorities. In the case of road planings arising from trunk roads and motorways it was decided that data would need to be sought from the Highways Agency.

Road planings data are proving very difficult to collect and there does not appear to be a quick solution at regional level. The RAWPs have been able to collect useful data on local highways and the information that is accumulating may provide a basis for estimating, or developing a method for estimating, local highway planings where it has not proved possible to obtain figures. The Highways Agency, however, has not been able to provide data on planings from non-local roads and the ODPM is therefore discussing the scope for an alternative approach (that might cover all planings) with the industry. It is accepted, however, that collection has to be at reasonable cost to all involved, which might limit what can be achieved.

Conclusion

The quality of the statistics needed to monitor government policy in order to increase the use of alternative materials as aggregate is being improved steadily, and 2001 is the first year for which comparable data are available for both primary and alternative sources of aggregate. Nevertheless, further improvements to the quality of the statistics on alternative materials are essential, although they will never be as good as those for primary aggregates.

This article was prepared by the Minerals and Waste Planning Division of the Office of the Deputy Prime Minister (ODPM), August 2002.

Reference

1. Arup Economics and Planning, ‘Statistics on arisings and use of mineral and construction wastes as aggregates: Information collection issues’, April 1998, price £12 (ISBN 1-85112-080-7).