Rookery Pit Energy-From-Waste Plant

Presentation to Community Liaison Panel on various health-related issues. 14 February 2011 Rookery Pit Energy-From-Waste Plant THE GROUP

Topics to be covered • Health Modelling • Basic Principles • Results of Modellings • Data sources used • Comments on Professor Paul Connett • Covering specific health impacts raised in presentation • Failures in Emissions Control • How emissions are monitored and who is responsible • What can go wrong and how is it prevented • Health impacts of an emissions control failure • Actions of the EA

What is a Hazard Many substances, both manmade and natural, are hazardous to health. This does not mean that they are all banned. For most chemicals, there is a threshold below which it is extremely unlikely that adverse effects will occur. Above this level, there is an increased likelihood of adverse effects. For a few chemicals, there is no established threshold, but lower levels are associated with lower likelihoods of adverse effects. This means that merely stating that a substance is hazardous is not sufficient information.

What is a Risk Assessment The model used is the hazard – pathway - receptor model. In a risk assessment, we consider how the hazardous substance can reach humans (the pathway) and in what quantity. The human is termed the receptor. We can then consider and quantify the risk to health and compare this to benchmarks for acceptable risk. Goes beyond the simple assertion: Chemical X is hazardous Incinerators release Chemical X Therefore Incinerators are hazardous.

Basic Approach to Human Health Risk Assessment (1) Calculate atmospheric concentrations of pollutants. Compare with air quality objectives. Use US EPA methodology to calculate ingestion rates (i.e. how much of the pollutant reaches a person), via People eating soil. Pollutants landing on soil and being taken up by plants. Pollutants landing on plants. Animals eating plants. People eating plants and animals. USEPA methodology is fully referenced with hundreds of supporting scientific papers. Use ingestion rates to calculate risk.

Basic Approach to Human Health Risk Assessment (2) For non-carcinogenic chemicals: Calculate the daily dose and divide by the reference dose, to get the hazard quotient. Add the hazard quotients together to get the hazard index. If the hazard index is less than 1, there would be no adverse health effect. For carcinogenic chemicals: Calculate the risk of contracting cancer. This will not be zero, but may be vanishingly small. Add all the risks together. Compare the risk with the accepted annual risk of 1 in a million. In the UK, the 2007 cancer diagnosis rate was 4,890 in a million and the death rate was 2563 in a million, according to Cancer Research UK.

Results of Human Health Risk Assessment Considered thirteen residential receptors, four farmer receptors and four fisher receptors. For non-carcinogenic risks: Highest residential index was 0.048 Highest farmer index was 0.45 Highest fisher index was 0.80 For carcinogenic risks: Highest residential risk was 1 in 58 million Highest farmer risk was 1 in 13 million Highest fisher risk was 1 in 32 million All risks based on conservative assumptions High fractions of locally grown food. High emission rates of pollutants Hence, conclude that there is not a significant risk

Sources of Health Modelling Data • The HHRA is based on published protocols and standards. For example. • The Human Health Risk Assessment Protocol is thoroughly referenced. 38 pages of references to support the methodology 10 pages of references to support the chemical-specific parameters • Air Quality Standards and Objectives are based on assorted peer-reviewed research • Expert Panel on Air Quality Standards reviews all relevant research

Professor Connett – Health Issues • Very long presentation, raising many points. • Only addressing health issues today. • Key points on health: • “Toxic Ash” - incinerators produce bottom ash and APC Residues. • “Incinerators put many highly toxic and persistent substances into the air”. • Incinerators release nano-particles which are bad for you.

Professor Connett (2) “Toxic Ash” Incinerators produce bottom ash and APC Residues Bottom ash is reused for aggregate across Europe. APC Residues are hazardous. Professor Connett says 1 tonne toxic ash per 4 tonnes of waste. Actually 1 tonne of APC Residues per about 20 tonnes of waste. “Incinerators put many highly toxic and persistent substances into the air”. Fails to distinguish between hazard and risk. Fails to explain what “many” means or to put it into context. Could equally say “fireworks” or “bonfires” or “cars”…

Professor Connett (3) Nanoparticles Agree that these are not good for health. However, they are efficiently captured by bag filters. Nano-particles are not like billiard balls – they interact with each other and with larger particles, and they stick together. Limited measurements available – see papers by Buonanno et al (2009 and 2010) – but they suggest that nanoparticles are removed efficiently and that incinerators are minor sources of them. Again, Professor Connett does not distinguish between hazard and risk.

Failures in Emission Control (1) - Monitoring Continuous Emission Monitoring Systems (CEMS) 1 system per line plus a shared spare. Monitors NOx, SO2, CO, Dust, HCl, VOCs. Certified to BS EN 14181, MCERTS Certified. Results available for inspection by EA, and put on public register. Results linked to main computer and will trigger alarms Periodic Emission Monitoring Other pollutants cannot be monitored continuously. Periodic sampling carried out every 3 months by independent company. Dioxins, furans, metals – sample sent to laboratory. Results sent to EA and put on public register. Operations Manager is responsible for emissions. Environmental Manager has day-to-day responsibility.

Failures in Emission Control (2) – What can go wrong Significant variation in waste composition (CO, VOC peaks) Controlled by waste mixing. Minimised by combustion control. Lime injection system failure (acid gas peaks) Lime cake on filter will minimise emissions. Spares kept to allow rapid repair of system. Bag filter failure (dust peaks) Many bags, so a single failure has a minimal impact. Plant can run without a compartment, so can close off compartment and blank off burst bag. Ammonia system failure (NOx peaks) Never known this to happen. Flow alarms on ammonia, duty and standby pumps.

Failures in Emission Control (3) – Impacts on air quality Environmental Permit Application includes assessment of impact of “Abnormal Operation”. All are short term problems. Impact has been assessed from dispersion modelling. Emission concentrations taken from experience from other plants. If the problems occurred during worst case weather conditions, impact is still no more than 25% of air quality objectives.

Failures in Emission Control (4) – Role of the EA If there is an exceedence: Operator must inform the EA within 24 hours. Operator must carry out an investigation and provide further details within a short period. EA will categorise the exceedence. EA Enforcement Options: Warning Letter Enforcement Notice – solve the problem within a defined time. Suspension Notice – stop operating until the problem is solved Revocation of the permit Could be combined with prosecution

Thank You for Listening Q & A Session

Rookery Pit Energy-From-Waste Plant