Sustainable solutions for waste disposal: Marley Roofing

In the mid 1990’s Marley Roofing set itself a challenge to become the environmental leader in the building materials sector. This is being realized through numerous environmental improvements at all sites and through working with the Building Research Establishment (BRE) to develop life cycle assessment data for its whole product range, helping communicate Marley’s sustainability credentials.

In 2001, Marley was the first company to be awarded Certified Environmental Profiles and certificates (based on Life Cycle Assessment data) under BRE’s Certified Environmental Profiles Scheme. In 2004 Marley became the first company to achieve re-certification under the same scheme. As a result of this study, all Marley’s products were awarded “A” ratings in the Green Guides to Specification.

Marley Roofing has instigated a significant program to reduce waste at source. At its Beenham site, concrete waste is crushed and re-used as a partial replacement for aggregate. This not only reduces disposal to landfill, but also achieves savings of 15,000 tons aggregate/year.

In addition, an earlier project has successfully treated pigmented wastewater, saved on tanker disposal of waste, while at the same time re-using treated water in the process. However, this latter initiative still resulted in solid filter cake having to be disposed of to landfill.

This project describes how the site has taken the next step, combining waste streams in order to provide the factory with a sustainable solution to the problem of disposal of pigmented slurry waste arising from its production processes.

Benefits realized have included:

• Elimination of a hazardous waste stream, previously sent for landfill;
• Reduction in waste costs;
• Elimination of a bulk waste storage facility;
• Elimination of a risk of leakage of semi-liquid waste to groundwater;
• Improved housekeeping;
• Reduction in lorry movements.

The solution has seen waste handling costs reduced by 50%, saving £25,000 (US$ 44,600) per annum and diverting 288 tons of hazardous waste from landfill.

The Problem

The Marley site at Beenham, near Reading, Berkshire, manufactures a range of concrete roof tiles and associated fittings. As a result of the manufacturing process a number of waste streams are generated.

One of these waste streams was that of pigmented liquid slurry waste, originally collected in a sump and taken by tanker from the site for treatment/disposal to landfill, with any residual solid material excavated from the sump and also sent to landfill.

In 2004, it was known that the number of hazardous waste landfill sites was going to be substantially reduced as a result of government legislation. Haulage costs therefore, would undoubtedly increase the disposal costs of this material.

The Solution

An existing scheme in place at Beenham crushes concrete tile waste and recycles it back into the process as a primary aggregate substitute. It was suggested that the solid waste filter cake could also be crushed and filtered back into the process.

This project has not only eliminated the need for hazardous waste landfill, it has also benefited the company by reducing waste handling costs by 50% per annum.

Project Detail

Benefits

Marley Roofing manufactures an extensive range of concrete roof tiles and associated fittings on several automated, semi-automated and hand-made production lines at their factory at Beenham, Berkshire.

There have always been waste streams generated from these activities, but with the introduction of a formal environmental management system during 2000/2001 and ultimately certification to ISO 14001, there has been a focus to re-use, reduce or recycle waste wherever possible.

One costly waste produced was that of pigmented slurry waste arising from colour changes, wash-downs, and cleaning and maintenance operations.

In 1999 the company commissioned an effluent plant to treat waste pigmented slurries. Treated liquid effluent arising from the plant was recycled back in to the manufacturing process negating the need to have waste liquid slurry removed by tanker for treatment/landfill. This however, left a solid waste known as the ‘filter cake’, which had to be disposed of as special waste because of the pigments and treatment chemicals it contained.

Despite this recycling initiative, waste disposal costs still remained high. It was realized that the single most expensive cost was that for the disposal of the filter cake. This solid waste was required to be disposed of as special waste and was costing £25,000 per year.

As part of the factory’s overall plans for waste minimization, a waste concrete crushing facility is in operation, whereby a mobile crushing plant is brought onto site and scrapped/waste concrete products are crushed and recycled as an aggregate substitute. With government legislation leading to a primary aggregate tax and the fact it is a non-sustainable natural resource, any substitution for primary aggregate is welcome.

With landfill costs/tax increasing and destined to increase further in subsequent years, and the reduction of hazardous waste landfill sites around the country, it was inevitable that disposal costs would rise in the imminent future. It was thought that if we crush and recycle most of our solid waste products, could this be done with the filter cake?

The results of this project realized this ambition and the site now recycles all filter cake waste, resulting in a financial saving of some £25,000 per year on waste disposal.

Additionally, Environmental saving of some 288 tons of hazardous waste not having to be transported offsite for disposal to landfill and 288 ton of aggregate not having to be purchased and transported onto site have also been achieved.

Innovation

Although a number of concrete product manufacturers probably crush their solid waste, re-using it as a partial substitute for aggregate, and some companies producing pigmented concrete products, may be treating their waste water prior to disposal, very few companies are likely to have combined these initiatives, as detailed in this project.

Before any decision was made to actively recycle the filter cake, trials had to be undertaken to crush the material and feed it into the already crushed concrete waste at a rate of 10%. Several batches of roof tiles were made with an overall crushed waste aggregate substitute of 25%, which included the filter cake addition of 10%.

These tiles were sent to Marley Building Materials Roof Tile Process Development Department to be analysed to ensure there was no detrimental affect to the finished tile, which may have impacted on the customers who used them.

All analysis undertaken proved that there was no significant change either chemically, or performance related, to the product. With transverse strengths recorded for the trial batches being comparable to those recorded for tiles not containing any crushed waste filter cake.

Further large-scale trials were initiated and closely monitored, with no adverse effects being noted. As a result formulations were agreed allowing up to 10% of waste filter cake to be included in the overall crushed concrete waste.

As a consequence of this project, all filter cake waste is now crushed and put back into the process, saving 288 tonnes per annum going to ever decreasing hazardous waste landfill sites and at the same time, saving 288 tonne of aggregate from having to be purchased for the site per year.

Wider Applicability

Within the membership of the BPCF, there are a large number of companies and sites that manufacture pigmented roof tiles and pigmented paving products.

Any of these businesses involving the use of pigmented slurries and operating a crushing facility for recycling scrap/waste concrete, could also incorporate this process to help reduce waste disposal costs, aggregate use (and the subsequent taxes), and disposal to landfill, which is beneficial to both the business and the environment.

The project involved personnel from a range of disciplines including plant operators, local quality and environmental staff, technical staff and representatives from engineering and maintenance departments.

Marley Roofing is an MEBC member.

The Business Council for Sustainable Development – United Kingdom is the UK’s only affiliated branch of the World Business Council for Sustainable Development. The BCSD-UK is committed to the promotion of sustainable development and to explore the practical implications of implementation. It is an independent multi-sectored business group with a keen focus on action and projects.

The Midlands Environmental Business Company is a not-for-profit company and custodian of the Midlands Environmental Business Club formed in 1991. It is a regional multi-sectored network and the strategic partner of Advantage West Midlands in the Regional Economic Strategy for the development of the environmental technology sector. It too is very action focused.

Further information

• Marley Roofing
• Building Research Establishment
• The Business Council for Sustainable Development – United Kingdom
• The Midlands Environmental Business Company

Author BCSD-UK/MEBC Publication Date 12 Jun 2006 Document Type Case studies Issue/Topic Business Role/CSR Regional Network Region Europe Country United Kingdom Include In RSS WBCSD News & Updates