Incinerator (Energy Recovery Centre)
The waste to energy incinerator at Marsh Barton has been operational for some time now. AVF committee will arrange visits – see latest posts.
Questions from the Alphington Village Forum and operator answers are given below:
1. There will be a live display of the incinerator output on the website – will this show the average figures and also include the peaks in emissions? Yes. The website will show the average figures and peaks in emissions on a half hourly basis and a 24 hour average too, although the precise format has yet to be agreed with the Environment Agency, which is the regulator for such matters
2. Will the community be alerted when the plant is closed down and starts up again? We do not intend to do this for reasons of practicality. The facility will be shut down on a few occasions each year and will otherwise run 24/7, except for occasional (and unpredictable) times when the plant will be shut down because of breakdowns or for external reasons. At these times, the operating staff of the plant will be fully occupied and should not be distracted by other duties In any event, shut downs and start-ups must be highly controlled processes, to ensure that no cooling down occurs until all the waste has been combusted, in order to comply with the incineration emissions directive.
3. How will the community be alerted when emissions go above legal emissions limits? Any exceedance of the emission limits will be notified on the website, as verified by the Environment Agency.
4. What effect will the inclusion of household kitchen compostable waste have on the operating performance of the incinerator? It should be emphasised that DCC continues to prioritise waste reduction and home composting initiatives throughout Devon, and that most district councils now offer separate food waste collections (although we do understand that Exeter City Council does not at present). However, for the element that is not diverted using these initiatives, the facility will be able to process this waste as part of a mixed residual waste stream. The EfW plant is capable of processing a wide range of waste without detriment to its performance. As a result, the presence of food waste in this mix will not affect its performance one way or the other.
5. Will smoke detectors (containing radioactive particles) be allowed to be included in the incineration? If not, how will they be removed from the waste stream? It should be emphasised that we provide facilities to recycle smoke detectors separately at all of our Household Waste Recycling Centres and also some specialist electrical and electronic waste recycling banks around Exeter. As these detectors fall within this specialist category, they should not be disposed of in household waste bins; a fact that is widely publicized as part of the recycling campaign. These measures are generally effective at diverting the majority of detectors. However, sometimes some smoke detectors may make it into the residual waste stream, and the EfW facility is able to safely deal with this element of the waste stream; the size of one smoke detector in the overall volume of the waste and the capability of the gas treatment system is negligible.
6. What sort of commercial waste will be included in the mix? Please give examples. The proportion of commercial waste is very limited; only waste collected by some district councils on their ‘trade’ rounds will be accepted and this is of a similar composition to household waste including packaging, which might be contaminated with organic/ food waste. We do not intend to have commercial waste as a separately delivered waste stream. Typically, commercial waste consists of spent packaging (often laminated materials thus making recycling very difficult or impractical) and scraps paper, card and textiles. This material is sometimes contaminated with organic matter, such as food waste.
7. If there is insufficient waste to operate the plant, will it be shipped in from new areas or what will you do? There is currently enough residual waste within Exeter and the surrounding area to supply the facility with 60,000 tonnes per annum. In the unlikely event that waste volumes fall in the future to the point where there is insufficient waste from this catchment area to supply the facility, options would be reviewed at that time.
8. What plans are there for emergency action in case of a leak or flooding on the site? A flood action plan is in place, which sets out the procedures for the site in the event of inundation. Potential flood warnings are issued by the Environment Agency, or occasionally by the local authority. In any event, we have flood barriers to deploy across the facility, which would protect all main points of access and also prevent escape of waste from the site. These would be used to section off the waste bunker and reach a height of 1.2m. The delivery of waste would also cease in these circumstances. Despite the recent severe weather, there has been no impact on the site at all. It is also relevant to note that the plant has been designed such that major electrical and control equipment is not located on the ground floor, as an additional security measure.
9./10. Will bottom ash be stored on site? Where and how is the bottom ash and the flue ash being disposed of? There are a number of options for dealing with bottom ash produced by the energy from waste process. Bottom ash is a potentially useful material that may be re-processed to recover metals and produce a secondary aggregate. This involves storing the ash outdoors for a period of time to let it weather naturally and stabilise. It is then screened and processed to recover ferrous and non-ferrous metals and to sort the remaining ash into various grades of aggregate (the majority of ferrous metals are recovered from the ash before it leaves the EfW). While bottom ash re-processing facilities are commonly developed specifically to process ash from a single plant, the small capacity of the Exeter Plant and consequent small volume of bottom ash means that this is not an economical option. However, Viridor has a portfolio of EfW plants coming online in the next couple of years and hence it is working on a national strategy for bottom ash. This includes speaking to the current operators of bottom ash reprocessing plants in the UK to explore the options for regional solutions. Clearly any such regional solution will not be up and running for the commencement of Exeter EfW activities, so in the short term, arrangements have been put in place to dispose of the bottom ash at the Viridor operated landfill sites at Broadpath and Heathfield. The flue gas treatment residues – a separate component of the ash treatment – will be stored in a sealed silo on site before transport in a tanker to a specialist company for disposal in a hazardous landfill site. Final negotiations are in progress to select a disposal contractor, and recycling options are being explored for the longer term.
11. How is the plant operator working with DCC and ECC to maintain high levels of recycling? Whilst the plant’s operations include the extraction of metals from the bottom ash, which will enhance the level of recycling from the waste stream, the majority of recycling happens at a household level, where residents separate the waste (source-segregation). Consequently, this is something that the plant operator is not directly involved in. However, Devon County Council is keen to ensure that recycling is still a priority, particularly as it has been one of the top five authorities for recycling over many years. As a result, activity continues through the ‘Don’t let Devon go to waste’ campaign with social media, schools talks, advertising and other work to continue to promote the importance of recycling.
12. How will recyclable materials – cardboard and plastics – be removed from the waste stream rather than being incinerated? As before, householders can easily recycle these materials, using the waste collection services offered across the area (for example, Alphington residents receive a kerbside mixed plastics and cardboard recycling service). Facilities to recycle these materials are also offered at all of Devon’s household waste recycling centres. The emphasis is therefore to ensure all recycling is done before waste arrives at the plant, hence the ‘Don’t let Devon go to waste’ campaign and other activity. There is no facility to remove the cardboard and plastics at the plant; in any event much of this material will be either contaminated or contained in other materials which would make it impractical for recycling.
13. How will the cycle route from Alphin Brook be designed to pass the incinerator in safety to the small bridge to enable access to the canal? At present the current cycle route ends at Grace Road South, after which there is a short stretch of road (less than 300m) before a right-turn on to the bridge mentioned. Whilst there are no specific plans to enhance this cycle route as part of this development, there are options to look at it along with improvements to the bridge junction as part of the plans for the proposed Marsh Barton railway development.