New EfW recycling plant benefits from durable roofing and lining solutions

As local authorities continue to grapple with the issue of handling waste in an environmentally-sound and cost-effective way, waste-to-energy plants are proving to be a solution that offers a win/win/win approach, with lower environmental impact, lower waste management costs and a source of renewable energy.

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esigned by TATA Projects following a concept developed by Grimshaw, a new Energy-from-Waste (EfW) plant in Great Blakenham, near Ipswich, now generates sufficient electricity to power 30,000 homes by burning non-recyclable waste.

The 7316m² facility is set on a 3.94 hectare site and has been designed to power itself, in addition to supplying electricity to the National Grid. The plant diverts 269,000 tonnes of waste from landfill per year, reducing greenhouse gases by 75,000 tonnes annually. Even the ash produced does not go to landfill and is, instead, used as aggregate in local building projects.

It’s an impressive, progressive approach to waste management, which is also being used to educate future generations with an on-site visitor centre welcoming school trips and members of the public to see first-hand how waste can be used to generate energy, addressing two of the most significant environmental challenges we face in a single facility.

This environmental focus was carried through to every aspect of the design, construction and specification of the BREEAM ‘Excellent’ Suffolk EfW scheme, which is operated by Suez (Formerly SITA UK) for Suffolk County Council.

As Paul Leighton, Site Manager for Suez, explained: “It wasn’t enough for the site to simply fulfil its purpose of putting the county’s waste to good use, we also wanted it to be the best in terms of design, technology and operation.”

Respecting the local environment

Formerly occupied by a council works department, the site for the facility backs onto Gipping Valley; an area of historic waterways and local natural reserves.

What is EPDM?

An extremely durable synthetic rubber membrane derived from oil and natural gas, EPDM (ethylene propylene diene terpolymer) is widely used as both a single ply roofing system and as a pond lining solution. Available in a wide variety of widths, it can be installed as either a fully adhered system using manufacturer recommended adhesives and splice tapes or it can be mechanically fixed to the substrate.

Firestone has pioneered the use of EPDM as a roofing and lining membrane globally, with more than 1,500,000,000m² installed worldwide.

The plant has been designed to minimise the visual impact of the development, with the site arranged to create an open and positive front with a closed back that allows back-of-house facilities to be screened. The buildings have also been set back from the entry point, enabling landscaping, including planting of woodland and a wildflower meadow, to encourage biodiversity and natural habitat development.

The buildings themselves have been designed to combine energy efficiency with low visual impact. For example, the boiler house’s continuous louvred facade not only reduces the facility’s solar gain, but has also been designed as an aesthetic feature that alters the appearance of the building depending on the angle of view and time of day, echoing the changing character of the Suffolk sky. Meanwhile, large EFTE (ethylene tetrafluoroethylene) pillows installed in the roof maximise natural light in operational areas, reducing the required electrical load for the facility by minimising the need for electric lighting.

Membrane technology

The EPDM membranes, supplied by Firestone Building Products, for use on the flat roof areas of the boiler room, the tipping halls, the waste bunker, the electrical building, the workshops and the visitor centre, have also contributed to the environmental benefits of the roof at the Suffolk EfW plant. The same EPDM technology from Firestone has also been used to provide the lining for the fire reservoir that feeds the sprinkler system across the site.

Explained John McMullan, Commercial Manager at Firestone: “EPDM enhances the sustainability of a building by offering a long-term solution with excellent UV, chemical and puncture resistance. It has a proven track record, with installations dating back 35 years still providing the same level of protection against water ingress as they did at the time of installation. Its flexibility and durability even in extreme environments made it ideal for this installation.

“The client also wanted a roofing solution that would meet the goals of an eco-specification and Firestone’s RubberGard EPDM single ply roofing membrane has a ‘Good’ Green Guide rating and is completely inert with no plasticisers.”

Durability and longevity

Firestone supplied a total of 7000m² of RubberGard EPDM membrane for the various roof areas of the plant.

A self-adhesive, vapour control layer was laid onto the profiled steel roof deck. Mineral wool insulation was then used to enhance the thermal performance of the buildings as part of the facility’s energy management strategy.

To improve compression resistance and increase the roof’s durability, Firestone ISOGARD HD cover board was factory-laminated to the upper surface of the mineral wool insulation. A high density polyiso cover board, ISOGARD HD is just 12.7mm thick but has a compressive strength >800kPA (up to six times that of normal polyiso insulation) and enhances acoustic performance. This not only provided a robust, flat surface, making installation of the membrane quicker and easier, but also added structural strength to the entire roof system aiding the anticipated longevity of the facility.

Rob Dale, Head of Buildings & Architecture at TATA Steel Projects, explained: “The longevity of a roof is a major factor in its sustainability because it not only avoids future re-roofing and repairs, but also protects the fabric and contents of the building.

“Firestone ISOGARD is designed to spread the load on the roof and protect the insulation and substrate below, adding structural strength to the roof. It was therefore used to enhance the life-cycle of the roof, while aiding speed and ease of installation for the EPDM membrane.”

With ISOGARD adhered to the roof substrate, the contractor cut the 1.5mm thick RubberGard EPDM membrane to size and shape, using calculations provided by Firestone to ensure optimum use of materials.

John McMullan commented: “Working with contractors to provide technical specification support is an important aspect of both our quality and our value proposition. The contractor was trained by us, we advised on the products and adhesives used and we calculated the membrane layout for the roof to avoid any wasted product.”

For each area of roof, the membrane was positioned onto the roof surface. It was then adhered to the cover board using Firestone bonding adhesive, with all splices created using Firestone QuickSeam Tape, a three inch wide double-sided tape that creates an instant bond between each section of the membrane.

The flexibility and puncture resistance of EPDM was also key to the selection of Firestone’s GeoGard EPDM geomembrane as the lining system for the site’s fire reservoir. A similar process of cutting, laying and sealing the splices using Firestone’s QuickSeam system was used to create the reservoir.

Legacy for the future

The EfW plant in Great Blakenham is now fully operational providing waste management and renewable energy generation for homes across Suffolk and Norfolk aided by EPDM membranes that are flexible and durable enough to support the plant’s anticipated service life. With the landscaping maturing to attract animal and insect life and children learning about the environment in the visitor centre, it is also creating a legacy for the future.

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