|Viridor’s energy-from-waste incinerator at Ardley in Oxfordshire was officially opened in June 2014 by His Royal Highness the Duke of Gloucester. The £205 million, 26 megawatt facility processes 300,000 tonnes-a-year of residual waste a year from Oxfordshire county council and other local authorities and businesses.
Construction of the ERF began in November 2011 by a CNIM Clugston joint venture and the facility exported its first electricity to the grid in August 2014. The plant has been awarded R1 efficiency status (an EU energy efficiency threshold), one of just a handful of facilities in the UK to have been awarded this. Ardley EfW facility is conveniently located near Bicester in Oxfordshire, just off the M40 motorway.
The Marmac Scope of Work included the Redesign, Supply, Installation and Testing of the Electrical Services for the Lighting Installations (including emergency lighting, control and all related equipment to form a functional lighting solution) to the following areas:
• Process Area 02 – Boiler Hall.
• Process Area 03 – Flue Gas Treatment.
• Process Area 04A – Water Treatment.
• Process Area 04B – Electrical Rooms excluding DNO.
• Process Area 06 – Turbine Hall.
• Process Area 07 – Air Cooled Condenser Area.
• Process Area 08 – Bottom Ash Hall conveyor walkway only.
The design of the process lighting was primarily prepared to align with the parameters defined in the CNIM Technical Specification though the requirements of this document were then amended due to a value engineering process and further changes to bring the requirements into line with other similar facilities in the UK.
The lighting installation provided under the contract is supplied from
the main plant electrical distribution network. Two power supplies are
provided by CNIM from their essential and non-essential electrical
distribution systems. These supplies serve new electrical lighting distribution panel boards (Essential and Non-Essential) which
act as the focal point for the L&P distribution network. Essential and Non-Essential local distribution boards are sited in the process areas.
Generally, Marmac Services Ltd were to utilise cable ladders and cable trays provided (by others) under separate work packages. Nominal allowances were made for supplementary containment systems to carry final circuit cabling however during the process of the works, requirements changed and we installed more than 10km of heavy duty cable tray.
The tray is installed as a complete system and supported using steel channel and fixing clips, brackets, etc. The channel and fixings are of the same finish as the tray. Where the finish was tarnished during erection, it has been repaired or touched up with a paint system to match the original finish. Supports were designed to take the full weight of the tray and cables, along with any imposed loads such as wind etc., and imposed loads produced during installation and cable pulling. Deflection between supports does not exceed the manufacturer’s recommendation.
The cables supplied and installed include:
• Cables to lighting distribution / lighting control cubicles (panel distribution boards, sub-distribution boards etc)
• Cables to luminaires, lighting control devices, junctions boxes and other equipment related to the identified lighting installation
• Control cables to lighting control equipment (contactors, switches etc)
Marmac installed circa 50km of SWA cabling throughout the process areas. All cables are suitable for their place of installation and they are fully resistant to all the expected environmental features, such as ambient temperature, UV exposure, chemical attack, physical damage, etc either by virtue of their special construction or because of the protective features of their method of installation.
Cables are installed on ladders, cables trays and in conduits as required. All cables are of the lead-free and halogen-free and fire retarding type (LSZH) and are coded in accordance with the requirements of BS 7671. In general armoured cables are used for the lighting installation. Cables are appropriately labelled at the supply end and the equipment to which it connects. LSZH means cables are low smoke cables which burn with a zero halogen content. Braided flexible LSF cables have been used for final connections from junction boxes to luminaires in the main process areas.
The lighting environment is crucial to the overall function of the facility. It is essential building users have a visually effective environment. To facilitate this, the lighting strategy comprised varied solutions with control regimes put in place which enabled reduced levels of light for night / security use and to ensure that a selective lighting remains operational during mains failure conditions when the site is supported by standby generation.
Luminaires are suitable for their location and the operating environment. Emergency lighting is provided in all areas necessary, including exits and internal escape and assembly areas. Emergency and escape lighting installations conform to BS 5266-1: 2011 and BS EN 1838: 1999 (also numbered BS 5266-7: 1999). Luminaires for use on emergency lighting systems comply with BS EN 60598-2-22. Self-contained luminaires are ICEL approved and suitable for 3-hour operation. The method of providing emergency lighting is by:-
• Integral emergency battery packs within general florescent luminaires used for normal lighting.
• Stand-alone emergency spot light for high void spaces where general lighting is via high bay style lights
• Dedicated exit signage above escape doors
• External Emergency Bulkhead above final exit doors
The installation complies with BS 7671 Requirements for Electrical Installations. All exit and emergency exit signs are complete with illuminated pictogram compliant with the European Signs Directive. Escape lighting gives a positive indication of escape routes to outside of the premises and all signs giving such directions are lit to required levels.
A key factor in the visual environment was to provide user satisfaction and energy management by the application of lighting control. Lighting
control took a number of forms as outlined by the following
• Manual switching
• Automated control systems
• Or a combination of the above
The lighting control arrangement provides for a reduced (one third) lighting strategy to be implemented outside of normal working hours.
As there is a need for an element of essential lighting within the facility, this is provided by use of the one third night / security lights with the circuits provided for this function being supported on the site essential distribution network.
Where both central and local control of lighting is required, the lighting is managed through a relay / contactor module arrangement which is located at the lighting area distribution equipment.
The testing of the lighting and related electrical installation was carried out in accordance with all relevant and appropriate British Standards and codes of practice. These to include but not be limited to:
BS 7671: 2011(Including all up to date amendments) – Requirements for Electrical Installations: IEE Wiring Regulations, with reference to the following:
• Inspection and Testing
• Model forms for certification and reporting
• IEE Guidance Note 3 – Inspection and Testing (inc. Amendments)
• Rigorous functionality tests of each system
Marmac Services Ltd have tested, set to work and commissioned the installations to the full satisfaction and acceptance of CNIM. Marmac were responsible for carrying out all necessary quality assurance inspections detailed to our inspection and testing procedure document, setting to work and commissioning.
The Inspections had a particular emphasis to conformity with the specification, completeness of installation and verification of no mechanical damage.
The electrical tests in accordance with the IEE wiring regulations were completed for every final circuit and the results tabulated and presented on a Completion and Inspection Certificate for comment by CNIM.
All instruments were calibrated immediately prior to commencement of the testing and shall be re-calibrated in accordance with the manufacturer’s recommendation during the course of testing, as necessary. Copies of the calibration certificates are provided with the test results.
The facility began operation in 2014, treating 300,000 tonnes of non-recyclable waste each year. It now diverts at least 95% of Oxfordshire’s residual municipal waste away from landfill and generates enough electricity to power around 38,000 homes.