odour management plan

Version 1 Odour Management Plan

Issued By: Neil Pollard, General Manager Revised: 02.02.17 of 32

ANDIGESTION LTD

ANGEL WELLS

ANAEROBIC DIGESTION PLANT

ODOUR MANAGEMENT PLAN Version: 1

Revised: 02.02.17



Contents 1. INTRODUCTION .................................................................................................................. 3

1.1 Requirements for Odour Management at Angel Wells AD Plant ................................. 3

1.2 What is the Odour Management Plan (OMP)? ............................................................. 3

2. RISK ASSESSMENT AND ODOUR CONTROL ....................................................................... 4

2.1 Waste Deliveries ............................................................................................................. 5

2.2 Reception Hall ................................................................................................................ 6

2.3 Transfer Pumps/Pipelines .............................................................................................. 7

2.4 Mixing Tank and Waste Storage .................................................................................... 8

2.5 Pasteurisers .................................................................................................................... 9

2.6 Digesters ....................................................................................................................... 10

2.7 Digestate Screen ........................................................................................................... 11

2.8 Post Digester................................................................................................................. 12

2.9 Digestate Lagoon Storage ............................................................................................ 13

2.10 Digestate Loading Bay........................................................................................... 14

2.11 Digestate Application............................................................................................ 15

2.12 Bio-filter and Water Scrubber odour control unit. .............................................. 16

2.12 Building and Site Maintenance ............................................................................ 17

3. ODOUR COMPLAINTS ...................................................................................................... 18

3.1 Odour Complaints Procedure ...................................................................................... 18

3.2 Investigating the cause of the complaint .................................................................... 20

3.3 Remedial actions in the event of an odour complaint ............................................... 20

4. MONITORING ................................................................................................................... 21

4.1 Monitoring Plan ............................................................................................................ 21

4.2 Subjective Odour Assessment - Sniff Testing .............................................................. 21

4.3 Complaints Monitoring ................................................................................................ 21

4.4 Reporting the Results ................................................................................................... 22

4.5 OMP Audit and Review ................................................................................................ 22

5. COMMUNICATION ........................................................................................................... 23

5.1 Engaging with Neighbours ........................................................................................... 23

5.2 Engaging with the Environment Agency ..................................................................... 23

5.3 Staff Training and Awareness ...................................................................................... 23



APPENDIX ................................................................................................................................ 24

i. Protocol for subjective testing (“sniff-testing”) .......................................................... 24

ii. Odour Report Form ...................................................................................................... 28

iii. Angel Wells Process Flow Schematic ........................................................................... 29

iv. Map of Odour ‘Sniff Testing’ Locations. ...................................................................... 30

v. Air Treatment System Equipment Description ........................................................... 31

1. INTRODUCTION

1.1 Requirements for Odour Management at Angel Wells AD Plant Angel Wells Biogas is a centralised anaerobic digestion plant treating biodegradable source segregated materials such as industrial food wastes, animal by-products and municipal organic food waste.

1.2 What is the Odour Management Plan (OMP)? The Environment Agency specify that if it is likely that odour from your activities may cause pollution /annoyance beyond your site boundary, you will be required to have a written Odour Management Plan (OMP), which will have to be submitted to and approved by the Agency. The Environment Agency includes all waste processing activities to the list of sites that must implement and Odour Management Plan. Consequently, Angel Wells Biogas must maintain and adhere to an Odour Management Plan (OMP) as part of the Environmental Permitting process. The OMP details the control methods in place to prevent and contain odour emissions. It also specifies the responses to be taken in the event of odour release and the method applied to monitoring and review of odour management. This OMP will be reviewed and where necessary updated at a frequency of at least once per year. The most recent version of the OMP will be available on site.



2. RISK ASSESSMENT AND ODOUR CONTROL A detailed assessment of risk of odour from all processes at Angel Wells Biogas must be undertaken as part of the Odour Management Plan. It must include the following elements: a) Assessment of Odour Risk Identification of the sources of odour and assessment of the risk of odour from this source. This must be carried out for normal and abnormal situations, including worst case scenarios. For example

• From normal operations (including business and/or seasonal variations) – Raw materials (e.g. quality control, receipt and storage) – Operational activity

• From abnormal conditions – Meteorological (e.g. wind direction or strength, rainfall/flooding, low/high temperature,

inversions) – Breakdowns of process, waste treatment, abatement, instrumentation and other equipment,

utility of supplies. – Staffing issues (illness etc.) – Human error – Accident scenarios.

N.B. Accidental/emergency scenarios that may lead to an odour release e.g. a major spill event or flood are assessed in depth as part of the site Accident Management Plan. This includes the control methods, corrective actions and responsibilities. Those accident scenarios more closely linked to odour and with an increased likelihood of occurrence are also included in the Odour Risk Assessment below e.g. waste/digestate spills. A weather station will be located on site, in order to record the wind direction, wind velocity and air temperature. This information should be used to inform decision making in terms of risk assessment of site activities with any risk of potential increased odour emission. b) Odour Control Methods

Identify appropriate control measures (both physical and procedural) showing that you have considered:

• Minimising the inventory of odorous materials

• Minimising the evaporation of odour in the air

• Containment and abatement

• Dispersion

c) Actions, contingencies and responsibilities

• Action level – the point at which action will need to be taken to control an odour release

• Actions in the event of odour release

• Responsibilities for odour control For Bishops Cleeve Biogas this has been carried out by using the process flow chart for the site (See Appendix (iii)). Each process stage is assessed individually for sources of odour and to detail the odour control methods applied at that process stage. The assessment is given below.



2.1 Waste Deliveries

Source of Odour Receptor Likelihood

Source segregated bio-degradable food wastes to be collected for delivery to Angel Wells Biogas. Odours can be released from the waste collection vehicle due to spills or poorly covered waste exposed to atmosphere e.g.

• Leaky valves, poor stacking causing spills, overfilling causing a leak

• Venting, un-secured cover sheet.

Local population close to the transport route.

Medium

Control Measures

Routine Procedures:

• Pre-Transport Inspection of Waste (where collection vehicles are run by Andigestion Ltd)– secure stacking and containment.

• No overfilling of vehicles. Reject overfilled containers at point of collection.

• If possible avoid breaks and stoppage while in transit and loaded.

• Inspection of incoming waste delivery vehicles Equipment/Maintenance:

• Ensure suitability of equipment and methods to move that waste type prior to collection. Clean vehicles used (routine procedure to clean and check vehicles after waste is tipped).

• Regular maintenance of Andigestion vehicles ensures that vehicles are in good working order and not likely to breakdown while in transit.

Checks • Annual audit of procedures to check that drivers are aware of the need to carry out pre-transport

checks and are carrying them out as part of the EMS audit.

Action Level Actions Responsibilities

• Noticeable Odour at a 10m distance from covered vehicles.

• Waste seen leaking from vehicle.

Depending on the nature of the problem:

• Reject over-filled vehicles at the point of collection if possible.

• Contain, collect and wash out any spills immediately (seek help and inform management if required)

• Stop vehicle (parking away from populated areas) and ensure that the load is fully contained.

• Consider stricter specifications for the condition of waste in the contract with the waste supplier e.g. period of waste storage prior to collection, more regular collections, containment.

• Provide feedback with any issues to external hauliers

• Lorry Drivers Inspection, cleanliness of lorries during transit

• Management Ensure Lorry Drivers are carrying out inspections and suppliers are aware of the specifications of waste containment for collection. Site staff will check all vehicle containment and report any unsuitably covered vehicles for action to their operators.

• Environment Manager Organise audits and report findings.



2.2 Reception Hall


Source segregated bio-degradable food wastes delivered into and sorted/discharged in the Reception Hall. Odours are released from the following:

• Waste delivery vehicles as they discharge waste onto the floor for processing.

• Waste stored within the reception building.

• Waste spills left on the hall floor.

• Liquid run-off from waste materials

• Waste packaging output from de-packaging machines.

Local population to Angel Wells Biogas. Staff and visitors to the Site.

High

Control Measures

Routine Procedures:

• Waste vehicles enter Reception Hall immediately (except when waiting for previous vehicle to finish unloading).

• Hall doors kept closed except when vehicles are entering/leaving.

• Personnel doors to remain closed when not in use.

• Use of ‘fast-acting doors’.

• Wash down all waste spillages on the floor before new loads area allowed in.

• Tankered waste streams discharged directly into waste storage tanks.

• Delivery vehicles washed down to remove excess waste residues.

• Stored wastes to be treated without undue delay and under normal operating conditions, waste will be processed from the reception building into the waste holding tanks within 8 hours of arrival.

Equipment Use/Maintenance:

• Water scrubber: To remove water soluble odorous compounds and dust from the extracted air o Maintenance carried out as per manufactures recommendations, tracked by PPM system.

• Bio-filter: Used to biologically treat odorous compounds within air extracted from the reception building.

o Maintenance carried out as per manufactures recommendations, tracked by PPM system. o Routine maintenance work which requires a plant shutdown only carried out when no waste is

present in the reception building.

• Forced Air Flow System: To generate positive air flow to bio-filter extraction ducting. o Spare fan unit kept on-site. o Maintenance as per manufactures recommendations, tracked by PPM system.

• Drainage system: To prevent a build-up of standing liquids within the building. o Drainage sumps equipped with automatic pump to storage tank. o Maintenance as per manufactures recommendations, tracked by PPM system.

Checks

• Daily check for hall cleanliness (Daily Hygiene Checklist)

• Annual emissions check of bio-filter exhaust. • Annual audit of procedures.




• Hall doors regularly noticed left open.

• Manual gas monitor shows Occupational Exposure Level (OEL) for 8 hours of 10ppm H2S.

• Failure of odour control equipment.

• Noticeably high odour around the site during unloading

(Operators will have increased tolerance to odour, a load they find odourous is likely to cause a nuisance if not immediately controlled).

• Standing puddles of liquids observed

• If overpowering smell identified in the reception hall, move to a clean area, ensure hall doors are closed, report to management and prepare safe method for re-entry into the hall.

• Ensure odour control equipment is working as standard.

• If stored waste is excessively odorous, process immediately into the waste storage tanks.

• Clean up spillages causing odour.

• Undertake training or where necessary disciplinary action if reception hall procedures are routinely being ignored.

• Loads considered ‘malodourous’ to be investigated and reported as a non-conformance.

• Work with suppliers to reduce any decay of feedstock prior to delivery.

• Ensure runoff is regularly removed, maintain hard surfaces and check that the drainage system is working and sumps are cleared regularly.

• Footwear cleaning facilities provided at exits so that no odourous materials are walked outside by personnel.

• Lorry Drivers Follow door closing procedures and ensure spills are cleaned. Inform management of major incidents involving odour.

• Plant Operator Follow routine procedure, carry our Daily Hygiene Checklist.

• Management Ensure staff members carry out routine procedures. Identify failure to follow procedures and take corrective actions. Carry out Weekly Clean Areas Check.

• Environment Manager Organise audits and report findings.

2.3 Transfer Pumps/Pipelines


Source segregated bio-degradable food waste substrate transferred through the processing stages. Odours can be released from a spill event due to:

• Leaky seals and joints, burst pipes

• Spills during routine maintenance of pumps


Low

Control Measures

Routine Procedures: • Thorough and immediate clean-up of any spills during pump maintenance.

• Pre-flushing pipework and pumps with water before maintenance work carried out.

• Dilution of sludge to ensure sludge thickness does not cause high pressure and burst pipe joints or damage pumps.


• Areas of pumps are bunded to contain spills for quick and easy clean-up operations.

• Pump maintenance as per manufacturer’s recommendations, tracked by PPM system. Checks

• Daily Plant Log includes visual check around the plant and checks of bunded areas e.g. pump’s.




• Anomalous noise, heat or vibration of pumps

• Cracks on pipework indicating a build-up of pressure

• Bad smell noticed in the proximity of pumps

• Liquid or gas leaks noted

• Liquid spill alarm triggered in pump container.


• Isolate leaky pump/pipeline and by-pass (if possible) while repairs are carried out.

• Use wet vacuum to clean-up spills during maintenance.

• If the sludge is very thick and severely affecting flow, dilute with water or effluent.

• Plant Operator Clean up spills during maintenance. Carry out Daily Plant Log.

• Management Manage sludge thickness. Ensure staff members carry out routine procedures.

2.4 Mixing Tank and Waste Storage


• Biodegradable waste substrate under decomposition and treatment.

Odour could be released from the waste substrate due to a leak event (overfilling of the tank or tank failure).

• Odourous air released from the mixing tank. Odour could be released due to a fugitive emission of headspace gas if negative pressure not maintained.


Low

Control Measures

Routine Procedures:

• Mixing tank kept under 90% full.

• Negative pressure maintained in Mixing Tank / Waste Storage Tanks. Equipment Use/Maintenance:

• Bio-filter: Used to treat odourous air extracted from the mixing tank / effluent tanks. Maintains negative pressure on waste storage tanks.

o Maintenance carried out as per manufactures recommendations, tracked by PPM system. o Routine maintenance work which requires a plant shutdown only carried after isolating Mixing

Tank headspace to contain odour. Checks

• Daily Plant Log includes visual check around the plant, including all storage tanks

• Routine maintenance checks on odour control equipment.

• SCADA continuous monitoring of head-space pressure, with alarms.


• Headspace pressure in Mixing Tank is over -0.5mbar.


• Check, reset or fix odour control equipment.

• Plant Operator and Monitoring Technician

Identify spills, odour. Undertake checks.



• Discharge observed from top of tank.

• Odour control unit not operating.

• Assess the headspace pressure setting in tanks, odour control unit.

• Manage feed regime to minimise odour by processing a batch to pasteuriser to relieve headspace pressure.

• Temporarily stop mixing if necessary (allow formation of a crust)

• Management Manage feed regime, mixing and headspace pressure of tank.

2.5 Pasteurisers



Odour could be released from the waste substrate due to a leak event (overfilling of the tank or tank failure).

• Odourous air released from the pasteuriser tank. Odour could be released due to a fugitive emission of headspace gas from pressure release valves, or vent pipes (connected to Mixing Tank)


Low

Control Measures

Routine Procedures:

• Batch fill/drain sequence to minimise headspace venting to Mixing Tank.

• Condensate traps stop vent lines from becoming blocked and venting from pressure release valves. Equipment Use/Maintenance:

• Pasteurisation Tank: Stainless steel construction to mitigate corrosion from food waste. o Annual inspection of tank wall thickness.

• Heat Exchangers: Stainless steel construction to mitigate corrosion from food waste. Pressure differential monitored across heat exchanger for advanced warning of blockage or catastrophic leak.

o Planned cleaning of heat exchanger based maximum allowable pressure drop over HE.

• Over/Under pressure relief valve: To protect tank against over/under pressure. o Maintenance and checks on seals of pressure relief valves.

Checks

• Monthly maintenance of pressure release valves to check for leaks.

• SCADA continuous monitoring of HE pressure differential, with alarms.

• Daily Plant Log includes visual check around the plant, including pasteurisers.


• Headspace pressure in pasteuriser exceeds overpressure setting, >5mbar.

• Leak identified.

• HE differential pressure alarm triggered on SCADA system.


• Stop flow to pasteuriser, use other pasteurisers if possible. Investigate cause and arrange corrective actions.

• Identify and resolve cause of excessive headspace pressure, e.g. blocked vent line.

• Identify cause of leak and take appropriate action immediately to contain.



• Management Manage headspace pressure and feed regime of pasteurisers.



• Tank wall thickness measured to be <1.5mm.

• Flush HE and arrange for cleaning as soon as possible.

• Thoroughly inspect thickness of complete Pasteuriser. Install stainless patch or replace Pasteuriser as required.

2.6 Digesters



Odour could be released from the waste substrate due to a leak event (overfilling of the tank or tank failure)

• Biogas released from the storage tank. Odour could be released due to a fugitive emission of headspace gas from pressure release valves or due to a gas leak in the roof.


Low

Control Measures

Routine Procedures: • Ensure availability of gas storage before routine maintenance tasks on CHP units, or gas handling

equipment.

• Automatic control of gas level within gas store/digester roofs, by SCADA system.

• Alarm signal sent prior to headspace vent pressure being reached.

• Condensate traps stop gas lines from becoming blocked and venting from pressure release valves.

• Digester dosed with FeCL2 to reduce sulphide compounds in the gas.

• Collection of biogas from digesters in gas storage membrane, flare used when gas storage is 95% full. Equipment Use/Maintenance:

• Double membrane gas holder: Used to store gas above Digester Tanks. o Maintenance and inspection as per manufacturer’s recommendations, tracked by PPM

system. Checks

• Weekly flare maintenance check.

• Monthly maintenance check of pressure release valves to check for leaks.

• Daily Plant Log includes visual check around the plant, including all tanks


• Headspace pressure alarm triggered (SCADA alarm).

• PRV valves discharging.



• Check/adjust/stop feeding digester as required.

• Start dosing with Fe.

• Increase generator load to relieve gas pressure in the system (e.g. change to gas bag level control rather than pressure control).



• Management Manage headspace pressure and feed regime of digesters.



• Flare off excess biogas to reduce pressure in tank headspace.


2.7 Digestate Screen


Digestate (digested organic material for use as a bio-fertiliser). • Odour could be released from the digestate

due to a leak event (e.g. faulty seals)

• Odour could be released from the contaminant material that is collected by the screen and temporarily stored in the screen collection bin.


Low - Med

Control Measures

Routine Procedures:

• Material collected by the screen is removed and disposed of to landfill prior to the build-up becoming an odour risk. Minimum frequency: Daily.


• Fine Screen: Used to screen digestate for any contamination prior to Digestate storage / despatch. o Maintenance as per manufacturer’s recommendations, tracked by PPM system. o Spare seals/wear parts stocked on site.

Checks

• Daily Plant Log includes visual check around the plant (including the screen), any leaks, unusual operation or high odour will be identified by the plant operator.


• Leak identified

• Strong smell from the vicinity of the screen.


• Suspend digestate transfer through the screen into storage. Identify leak and arrange maintenance immediately.

• If odour is being generated due to waste materials in the collection bin, arrange emptying of bin.

• Investigate cover on the waste collection bin if deemed necessary.

• Plant Operator Identify spills, odour. Undertake Daily Plant Log checks.

• Management Manage operations and emergency maintenance in the event of a leak/problem causing an odour.



2.8 Post Digester



Odour could be released from the waste substrate due to a leak event (overfilling of the tank or tank failure)

• Biogas released from the storage tank. Odour could be released due to a fugitive emission of headspace gas from pressure release valves or due to a gas leak in the roof.


Low

Control Measures

Routine Procedures:

• Ensure availability of gas storage before routine maintenance tasks on CHP units, or gas handling equipment.

• Automatic control of gas level within gas store/digester roofs, by SCADA system.

• Gas flare in place for occasions when excess gas is produced • Alarm signal sent prior to headspace vent pressure being reached.

• Condensate traps stop gas lines from becoming blocked and venting from pressure release valves.

• Digester dosed with Fe to reduce sulphide compounds in the gas.

• Collection of biogas from digesters in gas storage membrane, flare used when gas storage is 95% full. Equipment Use/Maintenance:

• Double membrane gas holder: Used to store gas above Digester Tanks. o Maintenance and inspection as per manufacturer’s recommendations, tracked by PPM

system. Checks

• Weekly flare maintenance check.

• Monthly maintenance check of pressure release valves to check for leaks.

• Daily Plant Log includes visual check around the plant, including all tanks


• Headspace pressure alarm triggered (SCADA alarm).

• PRV valves discharging.



• Check/adjust/stop feeding digester as required.

• Start dosing with Fe.

• Increase generator load to relieve gas pressure in the system (e.g. change to gas bag level control rather than pressure control).

• Flare off excess biogas to reduce pressure in tank headspace.


• Any significant emissions of unburned biogas (including the operation of the pressure relief valves) and the



• Management Manage headspace pressure and feed regime of digesters.



operation of the flare shall be recorded.

2.9 Digestate Lagoon Storage


• Digestate (digested organic material for use as a biofertiliser).

Odour could be released from the digestate due to a leak event.

• Biogas released from the lagoon cover vents. Odour could be released during filling of the lagoon as air is expelled from cover.


Low

Control Measures

Routine Procedures:

• Water levels in lagoon cover sump/float system maintained to remove ‘slack’ material in cover.

• Carbon filters installed on vent points of lagoon. Equipment Use/Maintenance:

• Carbon Filter: Used to treat exhaust air from Lagoon cover vents. o Change out of spent carbon as per manufacturers recommendations/as required (odour

released from filter). o Draining condensate from carbon filter.

• Sump/Float System: Used to remove slack material from cover of lagoon.

Checks

• Daily Plant Log includes basic check for odour from the bags and level of water in float system.

• Quarterly odour monitoring from locations around the site.

• Weekly PPM check that sump pump is operational.


• Lagoon 95% full

• Leak identified

• Cover of lagoon filling with water.

• Cover of lagoon dry of water.


• Stop filling operations if an odour problem is identified, until resolution can be found.

• Undertake daily odour monitoring (sniff testing) at the gas outlets of the bags to assess if a consistent odour problem is being experienced.

• If a leak is identified, stop filling, drain bag to other storage. Inform EA and arrange corrective actions.

• Pump excess water off lagoon cover, and check pump/sump system.

• Pump sufficient water onto lagoon cover to fill sump/float system.



• Management Manage filling regime and use of back-up activated carbon where required.



2.10 Digestate Loading Bay



Odour could be released from the digestate due to a leak event during tanker filling e.g. leaky seals/connector pipe.

• Odour release from displacement of tanker air during filling.


Low-Med

Control Measures

Routine Procedures:

• Tanker loading procedure – all tankers must connect to carbon filter. Includes a check that the cone seals are operations and air venting/treatment is working as per normal.

• Spills are cleaned up immediately. Equipment Use/Maintenance:

• Carbon Filter: Used to treat exhaust air from tanker loading. o Change out of spent carbon as per manufacturers recommendations/as required (odour

released from filter). o Draining condensate from carbon filter.

• Spill kit located at the loading cone. Checks

• Annual air emissions monitoring from the outlet of the activated carbon filter by UKAS accredited body using MCERTS.

• Quarterly odour monitoring from locations around the site.

• Weekly check of Spill Kit contents. Replenishment as required.


• Repeated occurrence of spillages.

• Odour apparent at outlet of carbon filter.

• Odour complaint correlated to loading activities.


• Re-train drivers on loading procedures.

• Stop filling operations if an odour problem is identified, until remedial action can be taken.

• Replenish carbon in filter.

• Ensure the couplings are the correct fit and system and maintain the connection hoses on site


Identify spills, odour. Carry out routine procedure.

• Management Manage activated carbon filter and staff awareness of routine procedure.



2.11 Digestate Application



Odour could be released from the digestate due to a spill event while spreading. Odour could be released during land application due to ammonia volatilisation of the digestate exposed to air and transported on prevalent winds.

Local population that live or work close to site of spreading.

High

Control Measures

Routine Procedures:

• Follow best practice in spreading techniques, suitable to the land, crop and area.

• Where possible, incorporate Digestate into soils as quickly as possible after spreading. i.e. follow with plough when spreading to stubble/land to be drilled.

• Avoid spreading in adverse weather conditions e.g. high winds, extremes of temperature. Equipment Use/Maintenance:

• Equipment type specified by Andigestion’s specialist Digestate spreading contractor.

Checks

• Farm visits and audits of spreading activities.


• Leaks identified in tank or from valves

• Noticeably strong odour prevalent at site of spreading activity after 24hours.

• Official odour complaint.

• Spill event


• If a major spill occurs, assist with the organisation of containment/clean-up.

• Stop spreading during bad weather and wait for improvement.

• If a persistent odour problem is identified due to close proximity to local population, consider suspending spreading at that location.

• Specialist Contractor Liaise with farmers and spreading contractors re techniques applied/spreading permit, spill events.

• Management Manage odour complaints.



2.12 Bio-filter and Water Scrubber odour control unit.


Odourous air streams collected to the bio-filter for treatment could be released to air as an odour emission if the bio-filter was not fully operational (and alternative actions not taken). This includes:

• Odour released from the Reception Hall, Mixing Tank if the odour control unit is not available.

• Odour emitted from the bio-filter stack outlet if the water scrubber is not fully functioning.


Low

Control Measures

Routine Procedures:

• Operation of odour control system to remove odours from Reception Hall, Mixing Tank and Pasteurisers Head-space.


• Extraction Fans: Used to pull air through scrubber and Bio-Filter. Duty/Standby Arrangement. o Regular inspection for abnormal noise or vibrations, tracked by PPM system. o Greasing at intervals specified by manufacturer, tracked by PPM system.

• Humidifier: Used to humidify air prior to treatment in bio-filter. Humidity is required to maintain the health of ‘odour eating’ bacteria within the filter.

o Maintenance as per manufacturer’s recommendations. Tracked by PPM system.

• Scrubber: Water within the scrubber is used to dissolve soluble odourous compounds within the air stream.

o Automatic circulation of water as per manufactures recommendations, tracked by PPM system.

• Bio-Filter: Large surface area of bacteria used to consume the odourous compounds within the air stream.

o Replenishment of growth media (wood chip.) as per manufacturer’s recommendations, tracked by PPM system.

Checks

• Quarterly odour monitoring of external locations around the site to check effectiveness of odour management.


• Air extraction fan not operational.

• Odour emanating from bio-filter stack.


• Switch to standby fan. Repair/replace faulty unit.

• Isolate mixing tank headspace and stop flow of waste into tank to reduce concentration of odour to bio-filter whilst issue is identified and resolved.

• Call out manufacturer of odour control unit to effect repair to system.

• Assess the condition of the biofilter media including the moisture content. If there are dry pockets of media, this should be mixed and irrigated.

• Assess the air stream entering the biofilter to ensure that the biology is

• Plant Operators Undertake biofilter and scrubber check on Daily Plant Log.

• Management Manage continuous operation of scrubber and biofilter in good working order to meet requirements. Reduce throughput of wastes whilst maintenance works are carried out.



not adversely affected by the presence of compounds which can be toxic at certain levels (e.g. ammonia).

• Monitor the air velocity leaving the biofilter to determine if there is a blockage restricting air flow.

2.12 Building and Site Maintenance


Odour resulting from the following;

• Work on any of the building doors, which require the doors to be open for a significant amount of time

• Work involving the removal of cladding from the building

• Work involving the movement of equipment into and out of the building


High

Control Measures

Routine Procedures:

• Reducing activities inside the building such as accepting deliveries, moving materials, loading, de-packaging

• Avoid carrying out the work in adverse weather conditions

• Communicating with the EA and Local Residents before starting any major work


• Lifting equipment/vehicles Checks

• Monitor the odour levels as work is carried out.


• Odour occurring at site boundary


• Stopping operations inside the building such as accepting deliveries, de-packaging

• Avoid doing the work with the wind in the direction likely to cause a complaint.

• Use of vehicles to move large amounts of equipment into or out of the buildings.

• Use of an offsite member of the odour panel to assess odour levels

• Communicating with the EA and Local Residents before starting the work and explaining what the work will entail.

• Plant Operator and Maintenance staff

Plan works to cause minimum disruption Minimise air escape by use of sheeting, and in instances where cladding is changed, replace one sheet at a time

• Management Manage communication with EA/residents



3. ODOUR COMPLAINTS

3.1 Odour Complaints Procedure If a complaint is received, the following procedure must be followed to ensure that the complaint is handled appropriately and actions taken to rectify the situation. See page 20.



3.2 Investigating the cause of the complaint The following questions should be asked to identify the reason for complaint and where the odour problem may have arisen:

• Is the process under control? (Have you received exceptionally odorous wastes, for example? Have putrescible wastes been left standing for too long before processing?)

• Have odour containment measures failed? (Has a door been left open, for example? Have odorous materials been stored outside a containment area? Have adverse conditions, such as weather, overwhelmed containment structures?)

• Have odour abatement technology failed? (Has a carbon scrubber become saturated, for example? Is the odour control system operating as per design? Is maintenance required?)

• Is the odour cause by an accident or emergency situation e.g. a spill or leak?

• Have your neighbours been exposed to emissions because of unfavourable night-time cold drainage flow conditions or other prevalent weather events.

3.3 Remedial actions in the event of an odour complaint The remedial action will depend on the source of the odour. However, sometimes the investigation will show that to stop the odour emission you need to stop some site activities temporarily. This is an important requirement of odour management. Contingency arrangements must be made immediately if this is required. Remedial actions for different odour sources are discussed in the Odour Risk Assessment above.



4. MONITORING

4.1 Monitoring Plan Monitoring of odour emissions is necessary to assess the effectiveness of the odour control measures on site. The objectives for monitoring at Angel Wells Biogas are to assess

• Exposure (walkover surveys and sniff testing)

• Impacts (complaints from the local community). There is no added benefit in measuring odour emission releases (e.g. using dynamic dilution olfactometry) as the impact on the key receptors can be clearly assessed through subjective testing. The relationship between control processes and odour are also sufficiently understood that further monitoring of this relationship is not warranted. Two forms of monitoring are carried out to assess odour release and impacts:

1. Subjective assessment of odour from the entire site

• Quarterly sniff testing outside the perimeter of the site, locations agreed by the Environmental Agency, see map in Appendix iv.

• Scheduled in the planned preventative maintenance (PPM) system as a work order to be carried out by the monitoring technician.

2. Odour Complaints Monitoring

• Carried out annually alongside the Fugitive Emissions Review in January.

4.2 Subjective Odour Assessment - Sniff Testing Steady state subjective testing will be undertaken on a quarterly basis for the whole site and monthly for the digestate storage lagoon by the site manager. The intention of this form of odour assessment is to confirm whether odour is under control at the site and trigger further action if a problem is identified. The assessment will entail the monitoring technician going to the locations marked on the map (Appendix (iv)) and undertake subjective (sniff) testing as per the method given in the Environment Agency Horizontal Guidance Note H4 Odour Management. The method is given in the Appendix of this OMP. It will also include an analysis of weather conditions using on-site weather equipment. The results will be reported to management should a potential odour issue be identified and further action taken to mitigate the situation. Subjective odour assessments will be carried out more frequently (e.g. daily or weekly) in response to the following conditions:

• If an odour problem arises or odour complaint – more regular assessment to establish where the problem has arisen and if it is continuing or a one-off event.

• If an odour solution has been put in place to resolve a problem, monitoring that the control method has been successful

• During a change to normal odour abatement procedures due to planned preventative maintenance of abatement technology e.g. odour control unit maintenance.

4.3 Complaints Monitoring Complaints data is the most direct and reliable form of monitoring whether odours from site activities are actually causing a problem. However, it is important to be aware that it can be vulnerable to systematic bias. It is considered that people tend to under-report odour problems and complaints statistics will tend to underestimate the impact the community feels. Odour complaints received by Andigestion from members of the public will be managed in accordance with the complaints procedure detailed above. The details will be added to the complaints log detailing all the information listed in the odour complaints procedure, if further information is required the odour report form



will be used. The odour issue will be resolved immediately and corrective/preventative actions put in place where appropriate. On an annual basis the odour assessment diary will be assessed as part of the Fugitive Emissions Review that is carried out in January. The nature and patterns of complaints will be evaluated to identify any persistent problems that could be resolved through more appropriate management. This process will be documented and recorded.

4.4 Reporting the Results The results of odour monitoring will be reported to management if a problem is identified. The review of odour complaints will be reported to management annually. Odour monitoring report forms are filed in the Angel Wells Biogas Reception with the other Planned Preventative Maintenance work orders. They will be stored for a minimum of 2 years as per standard practice for environmental management of the site. The Annual Odour Complaints review will be filed with the annual environmental reviews for the Environment Agency in the Angel Wells Biogas Reception.

4.5 OMP Audit and Review The OMP will be audited as part of the Environmental Management System (EMS) for Angel Wells Biogas. The results will be reported to management and further corrective or remedial actions followed up in accordance with the procedures of the EMS. The adequacy of the OMP will be evaluated in response to:

• The findings of odour assessment monitoring

• The findings of odour complaints monitoring

• Following any notable odour emissions and complaints

• As a result of the findings of Fugitive Emissions Review



5. COMMUNICATION

5.1 Engaging with Neighbours Engaging with neighbours who may be affected by the activities of the site is an important component of the OMP as it reduces any perception of threat felt by neighbours and they may be more accepting of the situation.

For all neighbours that may become affected by the odour risk, following an odour problem or complaint actions will be taken to solve the problem promptly and the neighbours will be contacted to:

• Work with the neighbours to pinpoint an odour source if is uncertain

• Reassure the neighbours that actions are being taken

• Assess the success of remedial actions

If an odour problem is consistently identified, it may be useful to ask the neighbours to keep a residents diary of odour emissions, which can be used to identify the extent and nature of the problem.

5.2 Engaging with the Environment Agency If operations at the plant undergo a temporary change which may result an increased risk of odour emission, the local Permitting Site Officer will be informed of the activities and the measures put in place to control odour. For example, planned preventative maintenance of the odour control system or construction works that may cause a change to waste control measures. The Environment Agency should be notified via a Schedule 5 Notification Form if an odour emission has been identified and constitutes a breach of permit i.e. an offensive odour has been identified beyond the site boundary as a result of activities at the permitted installation as perceived by an authorised officer of the Environment Agency. Following a review and update to the OMP, the Environment Agency should be notified of the changes to the OMP and agreement to the measures obtained prior to undertaking changes.

5.3 Staff Training and Awareness All staff will be made aware of the odour management plan and the significance of conformance to the OMP in order to avoid odour impacts. Staff members who have responsibility for undertaking odour control measures or identifying potential problems and carrying out remedial actions as detailed in the Odour Risk Assessment will be made aware of their responsibilities as detailed above (and sign that they have read the relevant sections of the OMP). Staff will be trained on those operational procedures that are critical to control odour release, they be shown the appropriate procedure to be followed prior to undertaking the task and read and sign the procedure to agree that they are aware of the consequences of non-conformance with the procedure.



APPENDIX

i. Protocol for subjective testing (“sniff-testing”) Source: Environment Agency Horizontal Guidance H4, part 1, appendix 8 This protocol is included here in order to ensure a consistent approach to the assessment of odours on and around PPC installations. This is a very useful quick test which can provide a subjective “snap-shot” assessment of the presence, strength and character of an odour either within an installation boundary, at the boundary or in the area/community surrounding the site. The assessment might be carried out for the following reasons:

1 • As part of the routine regulation of an installation

2 • By the Operator to assess his state of compliance, and

3 • As a tool in complaint investigation - used by Operator or Regulator. Routine assessments can help to build up a picture of the odour impact of the installation on the surrounding environment over a period of time. Assessments which are targeted at adverse weather conditions or particularly odorous cycles of an operation allow “worst case” scenarios to be developed. Ideally the same methodology should be used to follow up complaints. A record should be kept of the meteorological conditions at the time of testing together with information relating to the operations and activities being undertaken at the time. The general principles are covered below. A full procedure for assessing odour from facilities processing waste can be found by referring to reference 13.

1. General considerations When undertaking an assessment, the following points need to be considered.

• Frequency of assessment should be determined by the potential for odour generation, the number of complaints or as required by any relevant Permit conditions.

• Consideration may also need to be given to evaluating the sensitivity of the person(s) carrying out this form of assessment. If necessary this can be confirmed by means of olfactometry. Obviously anyone with a poor sense of smell should be excluded. It is important to remember that regular exposure to a particular odour can produce olfactory fatigue. This can be particularly relevant where an Operator carries out daily checks at the perimeter or further afield. It can be beneficial to get someone who does not regularly work at the site to carry out sniff testing.

• To improve (or to check) data quality the test can be conducted by two persons working independently during the same time period.

• The person(s) undertaking the assessment should avoid strong food or drinks, including coffee, for at least half an hour before undertaking the assessment. Strongly scented toiletries should be avoided as well as the use of deodorisers in the vehicle used during the assessment.

• Colds, sinusitis or sore throat can affect the sense of smell. Planned assessments should be re-scheduled if possible or undertaken by someone else, otherwise the fact should be clearly noted on the report.

• The health and safety of the individual undertaking the assessment should not be compromised. Containers or vents should never be sniffed where there is any possibility of them containing, or having contained, substances which may be harmful, or if the content is unknown. The Agency’s Health & Safety Procedures Manual should be consulted as appropriate.

2. Testing location

Where possible move from areas of weaker strength to stronger. The exact location will depend on the purpose of the assessment but when investigating off-installation odour start well down wind and move towards the



installation. It should be remembered that an odour may change in character over a distance as a result of dilution and/or conversion (see Section 3.1.4). A number of factors may determine the choice of location, including:

• permit conditions relating to the installation boundary or sensitive receptors

• complaints received

• proximity of housing to the installation • wind direction at the time of testing.

An assessment may involve walking along a route selected according to the above factors, or to the conditions found upon arrival. Alternatively points may be fixed in order to evaluate the changing situation over a period of some weeks or months, or may vary from test to test according to local conditions. The latter may be of use in identifying worst case conditions.

3. Data collection and recording

Parameters of interest are:

1 • detectability / Intensity 2 • extent & persistence 3 • sensitivity of the location where the assessment is being made with regard to receptors, and 4 • offensiveness

A note should also be made of any external activities such as agricultural practices that could be either the source, a contributor to, or a confounding factor in a particular odour event. The categories of intensity, extent and sensitivity are: DETECTABILITY / INTENSITY

1 No detectable odour

2 Faint odour (barely detectable, need to stand still and inhale facing into the wind)

3 Moderate odour (odour easily detected while walking & breathing normally)

4 Strong odour

5 Very strong odour (possibly causing nausea) EXTENT & PERSISTENCE (assuming odour detectable, if not then 0)

1 Local & transient (only detected on installation or at installation boundary during brief periods when wind drops or blows)

2 Transient as above, but detected away from installation boundary

3 Persistent, but fairly localised

4 Persistent and pervasive up to 50m from plant or installation boundary

5 Persistent and widespread (odour detected >50 m from installation boundary)



SENSITIVITY OF LOCATION WHERE ODOUR DETECTED (assuming detectable, if not then 0)

1 Remote (no housing, commercial/industrial premises or public area within 500m)

2 Low sensitivity (no housing, etc. within 100m of area affected by odour)

3 Moderate sensitivity (housing, etc. within 100m of area affected by odour)

4 High sensitivity (housing, etc. within area affected by odour)

5 Extra sensitive (complaints arising from residents within area affected by odour) OFFENSIVENESS: The assessment of the offensiveness of odour is necessarily based upon the subjective sensory olfactory response of an observer. Determination of offensiveness depends upon intensity in addition to character, frequency of exposure and persistence (see below). The determination of whether the odour is “offensive” should be made on the basis that episodes of odour exposure in the locality could be frequent and persistent. The determining officer may be exposed for a few minutes only but the determination needs to take into account the likely long-term response of nearby receptors who may be exposed on a regular basis. Clearly, some odours are more offensive than others but it should be remembered that any odour has the potential to be offensive, depending upon factors such as concentration, duration and frequency of exposure, the context within which the exposure takes place and other factors unique to the individual exposed. The instantaneous impression may be of a relatively inoffensive odour but regular exposure, particularly at high concentration, often leads to a change in perception.

The following matters should be considered when determining the degree of potential offence.

Nature/character - odours that would be generally accepted as ‘unpleasant’ will be potentially offensive. For example, odours from an oil refinery would generally be accepted as unpleasant in comparison to odour from, for example, a bakery. The strength of an odour referenced to its detection threshold can be quantified and the higher the odour strength, the more the likelihood of an odour being detected.

Frequency of exposure - odours that are released frequently or continuously from the installation are more likely to be determined to be offensive than occasional transient releases. Odour frequency is often assessed in conjunction with persistence in the environment.

Persistence - odours which persist in the environment for a long period after release (that is do not readily disperse to a level where the odour is no longer detected) are more likely to be judged as offensive. Less unpleasant odours may be offensive if the releases are continuous or frequent and persistent. The persistence of an odour is also affected by the meteorological conditions.

Categories for OFFENSIVENESS are, (taking into account strength, persistence and typical frequency of exposure):

1 Potentially offensive

2 Moderately offensive

3 Very offensive The observation period should be over a standard time, generally 5 minutes at each location. During this time the intensity and extent can be evaluated. A record should be made of the atmospheric condition prevalent during the assessment. In the absence of an anemometer, the wind speed can be approximated using the Beaufort scale. Installation-specific information should be recorded - activities being undertaken, deliveries made, process operating parameters, any departures from “normal” operating conditions or activities.



Beaufort scale



ii. Odour Report Form



iii. Angel Wells Process Flow Schematic

Mixing Tank 1: 1000m3

Pasteuriser 3: 15m3

Macerator

Pasteuriser 1: 15m3 Pasteuriser 2:

15m3

Reception/De-packaging

Hall

De-Packaging Equipment

Heat Exchanger

Digester 1 3500m3

Gas Injection

Odour Treatment

Angel Wells ANAEROBIC DIGESTIONPLANT

CHP1: 350kWe

Digester 2 3500m3 Digestate Storage

2000m3

Waste Feedstock: The plant will process 34,000 tonnes of organic wastes each year. All the waste will be unloaded

and processed within the reception building. Here the wastes will be de-

packaged where necessary before being pumped off to a waste storage tank.

Unlike other outlets for food waste, the energy and nutrient content of the waste

is recovered. Electricity Generation: The gas recovered

from the food wastes is burnt in Combined Heat Power generators. Around 8% of the electricity generated is used on site, to run the process

with the remaining 92% exported into the

national grid as renewable electricity. When at full capacity, the plant will be exporting

14GW.hrs of electricity each year. Enough to power around 4,200 3-Bedroomhomes.

Unlike other renewable power solutions, AD provides a consistent source of

renewableelectricty which isn't dependant on weather conditions, or time of day. The energy

released from the food wastes can also be stored as Biogas, with energy losses through

storage negligible.

Pasteurisation: From the Mixing Tank, waste is pasteurised at

70oC for one hour. This ensures any pathogens, weeds and

seeds are destroyed, and cannot cause harm to the public or

environment. Heat for pasteurisation is recovered from

the jacket water of the CHP generators, through a system of

heat exchangers.

Digestion: The pasteurised food waste is then pumped into one of

two, Digester Tanks. The AD process operates continuously,

rather than as a batch-wise process. The fully sealed (Anaerobic)

Digesters are 3500tonne concrete tanks, where the food is digested by

Anaerobes to release Biogas. Biogas is a mixture of 60%Methane

and 40% Carbon Dioxide. This is stored in the flexible gas membranes

which form the roof of the tank, before being utilised to generate

renewable electricity in the generators.

Trace elements are dosed to the Digesters to keep the bacterial colonies performing efficiently.

Odour Control: The air in the reception building and waste storage tank (Mixing Tank) is collected and treated through a Bio-Filter. The air from the pasteurisers is mixed into the air

within the mixing tank .Bacteria within the Bio-Filter consume odorous compounds generated by the decomposing foodstuffs

before expelling the cleaned air out of a chimney stack.

Ga

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atio

na

l Grid

FeCL2 Trace Elements

Digestate Dispatch

Fertiliser: After the food waste has been fully digested, a nutrient rich liquid fertiliser called Digestate is produced.

This contains 99% of the nutrients present in the incoming food wastes. This will be spread to local farmland, reducing the requirement for energy intensive mineral fertilisers, and

returning the finite resource of macro-nutrients required for plant growth, back into the soils. Around 30,000tonnes of

Digestate will be produced each year.

Storage Lagoon 1 9000m3

Fine Screen

Solid Wastes

Liquid Wastes De-Packaging and Maceration

Solid waste is macerated within the de-packaging units. Liquid wastes

are passed through a separate

macerator. Waste is chopped to 12mm or smaller and then

transferred to the mixing tank



iv. Map of Odour ‘Sniff Testing’ Locations. To Be agreed



v. Air Treatment System Equipment Description The following Equipment has been installed. Refer to the suppliers’ literature and associated drawings for further information:

No. PLANT TYPE/ MODEL FUNCTION

01 Odour Control Egg Crate Grille Enable low-cost and effective ventilation of rooms, each grille can be balanced to draw off a different volume of air

02 Odour Control Differential Pressure Transmitter

Monitors the pressure in the biofilter to ensure the biofilter roof is no damaged

03 Odour Control Supply Fan & Ancillaries

Supplies passive ventilation into the food reception building, the system pulls air through a louvre, through an attenuator and out through the specially selected nozzles

04

Odour Control

Weather Louvre

Intended to prevent the passage of water through the opening into which the louvre is mounted.

05 Odour Control Nozzles Distribute fresh air evenly

06 Odour Control Damper

Isolates air stream from main extraction ductwork to Tank extraction ductwork only.

07

Odour Control Damper Actuator

Automatically adjusts the position of the damper blade to the required position in conjunction with a suitable control interface.

08

Odour Control

Odour Control System

Extracts the air from the building, plant with in the building and external tank, scrubs the air and then polishes in the biofilter.

09 Odour Control Recirculation Pump

The pump is used to recirculate the water around the scrubber.

10

Complete System Control Panel HMI

The control panel HMI screen gives an operator an overview of the plants current conditions and operating settings.

odour management plan

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