LANDFILL GAS MANAGEMENT PLAN...LFG Flare Specifications Model: LMS Gas Flare. Flow Capacity: Multi Stage – 50m³ to 1000m³ per hour. Combustion: Retention Inspirators. Flue Stack:

LANDFILL GAS

MANAGEMENT PLAN

Henderson Waste Recovery Park

Rockingham Road, Wattleup

Barry Elliot

Director

Waste Gas Resources

Oct 2015

Revision 1 IW Projects March 2016

Landfill Gas Management Plan – Henderson Waste Recovery Park

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Table of Contents

1. OVERVIEW OF SITE AND LANDFILL GAS MANAGEMENT ................................................................... 4

2. SITE LOCATION AND SUROUNDING LAND USE ................................................................................. 5

2.1 Site Location ...................................................................................................................................... 5

2.2 Adjoining Land Use Zoning................................................................................................................ 5

2.3 Activities Undertaken at the Site ...................................................................................................... 6

2.4 Surrounding land Uses ...................................................................................................................... 6

3. EXISTING LANDFILL GAS EXTRACTION AND UTILISATION EQUIPMENT .............................................. 7

3.1 Landfill Gas Extraction and Utilisation Systems ............................................................................... 7

3.2 LFG Extraction and Conveyance System ........................................................................................... 7

3.3 LFG Processing and Fuel Supply System........................................................................................... 7

3.4 Stand-Alone Gas Flaring System ....................................................................................................... 7

3.6 Backup LFG Extraction and Combustion ........................................................................................... 8

Figure 3.1 – LFG Flare located at the HWRP .............................................................................................. 8

Figure 3.2 - Power Station located at the HWRP ...................................................................................... 9

Figure 3.3 - JGC 320 Technical Description ............................................................................................. 11

4. LFG PROCESSING AND EXTRACTION WELL DESIGN ......................................................................... 16

4.1 LFG Extraction Well Design ............................................................................................................. 16

4.2 LFG Processing ................................................................................................................................ 16

Figure 4.1 – LFG Process Flow Diagram ................................................................................................... 17

4.3 LFG Extraction Well Installation at the Site .................................................................................... 18

4.4 Post-Cell Final Capping Extraction Well Placement ...................................................................... 18

Figure 4.2 – Cell 6 Landfill Gas Collection Grid Layout – May 2010 ........................................................ 19

Figure 4.3 - Cell 6 Landfill Gas Collection - Typical Network Layout - November 2013 ........................... 20

Figure 4.4 LFG Extraction Well Construction Method ............................................................................. 21

5. LFG MANAGEMENT INFRASTRUCTURE MAINTENANCE .................................................................. 22

5.1 Extraction System Maintenance .................................................................................................... 22

5.2 LFG Processing and Fuel Supply Infrastructure Maintenance ....................................................... 22

Figure 5.1 ................................................................................................................................................. 23

6. LFG UTILISATION ENERGY INPUTS - OUTPUTS ................................................................................ 27

Figure 6.1 Power Station Energy Input/Outputs and Reserve Utilisation Capacity ................................. 27

7. LFG EXTRACTION WELL BALANCING............................................................................................... 28

8. LFG MONITORING ......................................................................................................................... 29

9. LFG CONTROL – POST COMMERCIAL UTILISATION ......................................................................... 30


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Table of Contents Continued

10. CONCEPTUAL SITE MODEL ............................................................................................................. 31

10.1 Conceptual Site Model Overview .................................................................................................... 31

10.2 Potential Sources of LFG .................................................................................................................. 31

10.3 Potential Pathways ......................................................................................................................... 31

10.4 Potential Receptors ......................................................................................................................... 32

Figure 10.1 - Conceptual Site Layout ....................................................................................................... 33

11. LFG HAZARD ASSESMENT .............................................................................................................. 34

11.1 LFG Composition .............................................................................................................................. 34

11.2 LFG Migration .................................................................................................................................. 34

11.3 Methane Hazard .............................................................................................................................. 35

11.4 Carbon Dioxide Hazard .................................................................................................................... 35

11.5 LFG Trace Gas Hazard ...................................................................................................................... 35

11.6 Summary of LFG Hazards ............................................................................................................... 35

11.7 LFG Control Measures ..................................................................................................................... 36

11.8 Hazard Identification and Risk Ranking ......................................................................................... 36

APPENDIX A LFG HAZARD ASSEMENT TABLES A1 – A15 ................................................................. 38

APPENDIX B EXTRACTION WELL LOCATION PLANS TABLE B1 – B9 ................................................ 54


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1. OVERVIEW OF SITE AND LANDFILL GAS MANAGEMENT

The Henderson Waste Recovery Park (HWRP) is a licensed Class 3 Landfill Site which is operated

and owned by the City of Cockburn.

The HWRP (the Site) receives commercial, industrial and household waste which is infilled onto

lined waste cells. The waste material is subsequently compacted and covered with a layer of inert

fill by waste compaction machinery.

This method of waste disposal provides the conditions necessary for anaerobic breakdown of the

organic fraction of the deposited waste to occur. One of the by-products of this process of waste

breakdown is the generation of methane rich landfill gas within the waste contained in the cell.

The landfill gas produced within the Site since 2006 has been extracted and utilised as fuel to

generate electricity.

The extracted Landfill Gas is utilised as the sole fuel source for internal combustion engines which

drive generators that produce electricity. The electricity produced via the extracted Landfill Gas is

exported directly into the Southwest Interconnected Grid at distribution level voltage.

The Landfill Gas extraction process and the consequent conversion of the Landfill Gas to

electricity, is undertaken on a continual basis 24 hours a day throughout the year.

The Landfill Gas Utilisation Infrastructure installed at the Site includes a stand-alone Gas Flare

System. This system can be utilised to manage excess extracted Landfill Gas via combustion of LFG

within the gas flare. The installed Gas Flare System has been designed to operate independently

from the electricity generation Landfill Gas supply systems.

Conversion of the Site’s Landfill Gas into electricity via the utilisation infrastructure installed at the

site has a twofold effect;

• Provides the physical mechanism for Landfill Gas management and control at the Site.

• Produces renewable energy whilst greatly mitigating the greenhouse warming potential of

the methane contained within the extracted Landfill Gas.

This Landfill Gas Management Plan is in current operation at the Henderson Waste Recovery Park.


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2. SITE LOCATION AND SUROUNDING LAND USE

2.1 Site Location

The Henderson Waste Recovery Park (HWRP) is located in Wattleup Western Australia, with entry

into the site via Rockingham road.

The Site is bounded by Rockingham Road to the West, a railway easement running parallel to

Moylan Road to the East and Dalison Road to the South. The site adjoins an operational limestone

quarry which is bounded by Russell Road to the North.

The HWRP is located within the Latitude 32 Development Area and will likely abut to or become

part of the land area of the proposed Intermodal Freight Terminal to be located within the

Latitude 32 Development Area.

The HWRP site is located on degraded land from former extractive industry uses. Several small

sections of greenbelt areas remain within site buffer zones.

2.2 Adjoining Land Use Zoning

The HWRP has the following adjoining land use zoning 0 - 500m from the site;

Reference

Point

Adjoining Zoning 0-

500m. Site is within

the Latitude 32

Development Area

Distance to

nearest

Building

2015

Distance to

Nearest

Dwelling

2015

Distance to

nearest

Dwelling Post

Latitude 32

North

Boundary

Resource Recovery

then Industrial

700m 850m 680m

South

Boundary

Transport 480m 480m >1km

East Boundary Infrastructure and

Reserve -Kwinana

Freight Terminal then

Transport

160m 160m >1km

West Boundary Transport then Parks

and Recreation

140m 140m >1km


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2.3 Activities Undertaken at the Site

Various operational processes are undertaken at the site. The incoming waste stream is strongly

targeted for resource recovery. This includes metal, white goods, batteries, timber, cardboard,

electronics and also recyclable items to be sold at the Sites’ Recycle Shop.

Activities undertaken at the site include:

• Waste acceptance and processing

• Waste recovery

• Recovered waste sales

• Waste landfilling activities

• Site administration

• Leachate, storm water and landfill gas management

• Green waste processing

• Renewable energy production

2.4 Surrounding land Uses

Typical current land uses surrounding the site include:

• Land use around Northern boundary of the site – quarry activities.

• Land use around Western boundary of the site – equipment storage, inert waste

processing and green waste mulching and processing.

• Land use around Eastern boundary of the site – railway transport, rural and market

garden.

• Land use around Southern boundary of the site – transport, rural & market garden

activities and equipment storage.


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3. EXISTING LANDFILL GAS EXTRACTION AND UTILISATION EQUIPMENT

3.1 Landfill Gas Extraction and Utilisation Systems

The Henderson Waste Recovery Park has Landfill Gas extraction systems fitted to all waste cells at

the site, it also contains a gas utilisation facility. This existing infrastructure provides the means to

control and beneficially utilise the Landfill Gas being generated at the site. The existing Landfill Gas

infrastructure has been operating at the site since 2006.

Landfill Gas (LFG) extraction and utilisation infrastructure at the Henderson Waste Recovery Park consists of 4 main systems, these systems are described below.

3.2 LFG Extraction and Conveyance System

The LFG Extraction and Conveyance System (ECS) consists of LFG extraction wells, well flow control valves, LFG well reticulation piping, LFG collection ring-main piping, moisture knock-out pots and LFG sampling points. ECS allows LFG to be extracted from the waste contained within the cells and for the conveyance of the LFG to the LFG Processing and Fuel Supply System.

3.3 LFG Processing and Fuel Supply System

The LFG Processing and Fuel Supply System (PFSS) contains LFG extraction blower, filtration units, plate heat exchangers, flow and pressure control system, LFG extraction blower variable speed drive, refrigerated chiller and monitoring & control systems. PFSS provides the motive force for LFG extraction and also for the removal of moisture from the LFG. PFSS also provides and regulates LFG pressure and flow to the power station engines’ gas train double block and bleed valves.

3.4 Stand-Alone Gas Flaring System

Stand-Alone Gas Flaring System (GFS) consists of an automated gas flare containing enclosed stack burner, centrifugal extraction fan and drive, gas receiving vessel, block valve & flashback arrestor and monitoring & safety control systems. GFS allows LFG to be continually flared unattended. 3.5 LFG Fuelled Power Station

The Power Station consists of three independent generator modules which convert the LFG extracted from the Henderson Site into electricity. The generator modules are GE Jenbacher JGS-320 containerized internal combustion powered generators.


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The JGS-320 generator modules are designed to operate specifically on various types of biogas including Landfill Gas. The JGS-320 are manufactured and supported by GE Jenbacher and are extensively used in biogas applications globally. Each generator module receives its fuel supply from an independent gas extraction blower and processing system (PFSS). This design provides an inbuilt redundancy so that LFG extraction and utilisation can be maintained during planned or unplanned maintenance and repair scenarios. Utilisation of LFG is maintained continuously on 24 hour, 7 days a week basis.

3.6 Backup LFG Extraction and Combustion

The LFG utilisation equipment includes a dedicated LFG flaring system. This is a stand-alone system which can operate independently of the engine LFG supply systems. The Gas Flaring System is manufactured by Landfill Management Systems. LFG Flare Specifications Model: LMS Gas Flare.

Flow Capacity: Multi Stage – 50m³ to 1000m³ per hour.

Combustion: Retention Inspirators.

Flue Stack: 7 metre stainless steel with refractory lining.

Gas Feed: Centrifugal Blower incorporating variable speed drive control.

Filtration: Stainless Steel knock out pot fitted with Stainless Steel Demister Pads

Figure 3.1 – LFG Flare located at the HWRP


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Figure 3.2 – Power Station located at the HWRP


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Figure 3.3 - JGC 320 Technical Descriptions


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4. LFG PROCESSING AND EXTRACTION WELL DESIGN

4.1 LFG Extraction Well Design

The LFG extraction system installed at the Henderson Waste Recovery Park utilises high density polyethylene piping for extraction wells, gas reticulation and collection headers. Polyethylene is used because of the materials propensity to withstand any corrosive effects from the LFG or any moisture contained in the LFG. The system consists of slotted polyethylene pipe (wells) installed both horizontally and vertically within the deposited waste (refer to Figure 4.4). Each well has an annulus of rock aggregate surrounding the installed slotted casing and are sealed at the well exit point with a clay plug and clean sand. The sealed wells are reticulated to a main collection header and are individually valved to the collection header. The collection headers are graded to barometric water drains to remove any condensed moisture as they are routed from the waste cells to the power station for subsequent delivery of the LFG for processing and consumption as fuel by the power station engines (refer to figure 4.3).

4.2 LFG Processing

The motive force for gas conveyance from the waste cells to power station is provided by a small negative pressure created within roots type lobe blowers located at the power station within the LFG Processing and Fuel Delivery Systems. The extracted LFG prior to utilisation within the power station engines is processed through a series of heat exchangers in order to remove entrained moisture and particulate matter (refer to figure 4.1). LFG Processing Stages

1. Pre Blower Particulate Filtration - removal of >2 micron sized particulate matter.

2. LFG Post Blower Cooling - initial LFG cooling stage.

3. LFG Reheat Exchange Cooling - LFG recuperative cooling stage.

4. Direct Cooling - dehydration of LFG by reducing gas temperature below dew point.

5. Coalescing Filtration of LFG - removal of condensed water from LFG flow.

6. LFG Reheat Exchange Warming - LFG recuperative heating stage.

7. Pre Engine Particulate Filtration - removal of >0.2 micron sized particulate matter.


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Figure 4.1 – LFG Process Flow Diagram

LFG WELLFIELD

LFG FILTRATION

POST BLOWER COOLING

REHEAT EXCHANGE COOLING

DIRECT COOLING

COALESCING FILTRATION

FILTRATION

ENGINE

REHEAT EXCHANGE


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4.3 LFG Extraction Well Installation at the Site

The Site has seven cells. All cells have either vertical and/or horizontal extraction wells installed, with all cells under active gas management (see Appendix B for well location plans). At the commencement of the project, the LFG extraction system type adopted was vertical extraction wells installed into completed and capped cells only. This type of extraction well installation occurred to Cell 1, 2 and 3. These wells are spaced at 40 metre centers. In order to maximise LFG capture and conversion at the Site, the facility (after several years of operation) adopted installation of horizontal LFG extraction wells. The horizontal wells are installed into completed layers of waste progressively as the waste cell height increases (refer to Figure 4.2). Horizontal extraction wells are installed with approximately 30 metres separation between wells. When the infilled waste has reached a height of < 6 metres above previously installed horizontal extraction wells, another set of horizontal extraction wells are installed at the new waste level in an offset pattern relative to the lower extraction well positions. Cells 6 and 7 contain horizontal gas extraction wells exclusively. Cells 4 and 5 have a combination of both vertical and horizontal gas extraction wells. Horizontal well installation has been undertaken at Henderson over the last five years and has proven to be an efficient component of the landfill gas control system. All future deposited waste is planned to have horizontal extraction wells installed as the waste cells progressively increase in height.

4.4 Post-Cell Final Capping Extraction Well Placement

LFG control and management at the HWRP pre-final capping placement is achieved by the installation of horizontal LFG extraction wells within the waste as cells are infilled. Upon completion of waste cell infilling and prior to the placement of cell final capping over the completed cell, a vertical gas extraction well drilling program will be undertaken on all completed waste cells. The installation of vertical extraction wells over the completed cells will ensure that all areas of the cell are under active influence from the LFG extraction system and thus ensuring maximum abatement of methane is occurring. The vertical well installations will require penetrations through the cell final capping to accommodate the vertical extraction well placement, these will be made good as part of the final capping installation. There is also the option to install the vertical wells after the final capping has been completed; however, the sealing of the penetrations becomes more complicated.


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HENDERSON WASTE RECOVERY PARK

HORIZONTAL GAS COLLECTION GRID LAYOUT – CELL 6

Figure 4.2 – Cell 6 Landfill Gas Collection Grid Layout – May 2010


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HENDERSON WASTE RECOVERY PARK

GAS COLLECTION – TYPICAL NETWORK LAYOUT CELL 6

Figure 4.3 - Cell 6 Landfill Gas Collection - Typical Network Layout - November 2013


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Figure 4.4 LFG Extraction Well Construction Method

xxxxxxxxxxxxx xxxxxxxxxxxxx aggregate annulus xxxxxxxxxxxxx xxxxxxxxxxxxx slotted hope pipe xxxxxxxxxxxxx xxxxxxxxxxxxx excavated trench

Typical Horizontal LFG Extraction Well Installation

clean sand

xxxxxxxxx xxxxxxxxx Clay Plug slotted pipe xxxxx xxxxxxxxx Bentonite Plug

xxxxxxxxx xxxxxxxxx xxxxxxxxx xxxxxxxxx

xxxxxxxxx xxxxxxxxx Aggregate Annulus

xxxxxxxxx xxxxxxxxx xxxxxxxxx x xxxxxxxxx xxxxxxxxx xxxxxxxxx xxxxxxxxx xxxxxxxxx Buried Waste

Typical Vertical LFG Extraction Well Installation


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5. LFG MANAGEMENT INFRASTRUCTURE MAINTENANCE

5.1 Extraction System Maintenance

Gas field extraction system maintenance is undertaken on the following basis: Monthly: Visual inspection of Ring Main, Reticulation Piping and Flow Control Valves for any damage or subsidence. Monthly: Check function of Moisture Barometric Drains and Pump Tanks. 2 Monthly: Check Extraction Well exit points for signs of air ingress or gas leakage. 2 Monthly: Vegetation clearance from all piping to maintain access easement. Annual: Physically check all valve flange bolts for correct tension. Check all valves for correct operation. Annual: Repaint Collection Ring Main and Reticulation Piping. Annual: Change out Gas Sample Test Ports.

5.2 LFG Processing and Fuel Supply Infrastructure Maintenance

Gas processing and supply system maintenance is performed on the following schedule: Weekly: Visual inspection of LFG Blower and Motor mountings, drive belts, oil levels.

1,500 hours: Change LFG Blower oil, check drive belts, piping connections and bearings.

5,000 hours: Clean Particulate filter, check all bolt tensions, Estop and Control Valves.

10,000 hours: Change drive belts, check monitoring calibration and DP drop across system.

20,000 hours: Check drive shafts for runout, inspect Coalescing Filter Elements.

30,000 hours: Testing of Drive Motor Windings, overhaul / replace LFG Blower.

40,000 hours: Replace Drive Motor, inspection / cleaning of Plate Heat Exchangers.


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HENDERSON WASTE RECOVERY PARK LFG POWER STATION – GENERATOR MODULES MAINTENANCE

SCHEDULE, INTERVALS & DURATIONS Figure 5.1


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6. LFG UTILISATION ENERGY INPUTS - OUTPUTS

The LFG utilisation infrastructure installed at the Henderson Waste Recovery Park has the capacity to utilise 244,839 Gigajoules of energy per annum. The conversion of 244,839 Gigajoules of energy by the installed infrastructure would produce 26,868 megawatt hours of electrical energy. Operational target for the LFG power station is 95 percent of available capacity. This target would require the conversion of 223,287 Gigajoules of energy to yield the desired 25,524 megawatt hours of electricity production per year. Currently this target is limited by LFG availability at the site. Current average annual exported electricity output is 21,000 megawatt hours. This equates to approximately 183,708 Gigajoules of energy being extracted and converted to electricity from the site per year. The LFG utilisation infrastructure consumes, for its own operation, approximately 4 percent of the electricity generated by the power station. This in-house consumption of electricity is equal to approximately 7,654 Gigajoules of energy being extracted and converted to electricity from the site per year.

Figure 6.1 Power Station Energy Input/Outputs and Reserve Utilisation Capacity

Mode of Energy Movement GJ of Energy pa MWH pa

Maximum energy utilisation/production capacity 244,839 26,868

Target energy utilisation/production capacity 223,287 25,524

Actual energy utilisation/production average 183,708 21,000

In house consumption of electricity 7,654 (875)

Reserve energy utilisation/production capacity 31,925 3,503

The LFG Utilisation Infrastructure is currently underutilised. The utilisation system has a reserve LFG processing capacity of approximately twenty percent on current LFG extraction levels. The reserve capacity of the system is further increased when the LFG Flaring System processing capacity is also taken into consideration.


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7. LFG EXTRACTION WELL BALANCING

LFG production rates within a landfill cell are variable over time and spatially within the cell. Production rates are dependent upon numerous physical and chemical parameters such as, but not limited to:

• Waste Type (amount of bio available carbon)

• Moisture content of waste

• Compaction variability within waste

• Anaerobic conditions

• PH within waste

• Chemical Interactions within waste Balancing of a gas well field is a necessary activity at any landfill that is under active LFG extraction. It is necessary to “Balance” the well field to ensure that all areas within the cell are being maintained at extraction rates that are in equilibrium with the particular influenced area steady state gas production rate. It is necessary to have a balanced well field in order to minimise ingress of atmosphere into the waste within the cell and conversely to minimise egress of LFG from the surface of the cell. A balanced well field ensures that maximum gas recovery is occurring for a given extraction system. Balancing a gas well field is essentially an iterative procedure. Once a gas field has been ‘Settled in’ by fairly intensive and repetitive monitoring and adjustment, the gas field operator becomes familiar with individual well performance and characteristics. This familiarity of well performance greatly reduces the workload to maintain the well field in a balanced state. Following the initially intensive period of monitoring and adjustment, well field management can be reduced to intervals ranging from weekly to monthly, depending on site conditions. The well field balancing protocol at the HWRP is to undertake weekly monitoring and adjustment of LFG extraction wells across the site in order to maintain the gas field in a balanced condition. Only small adjustments are made to any particular gas well, as any single adjustment to flow rate will affect the gas extraction rate of all other gas wells within the gas field. When a series of new gas extraction wells are commissioned, the gas field must be ‘Settled In’ through the iterative process of repetitive monitoring and adjustment until the gas field is balanced. Resumption of weekly monitoring and adjustment of the gas field is then undertaken. Gas well monitoring is undertaken utilising a Gas Data GFM series portable analyser. All gas samples are drawn through binder self-sealing test plugs.


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8. LFG MONITORING

Changes to pressures operating within the extraction system, or to the gas composition arriving at the power station is monitored on a regular basis. Deviations from normal operating values can be indicative that a problem is developing somewhere within the LFG extraction system. Changes to gas extraction parameters will be detected within the power station monitoring systems. These systems are observed on a daily basis and any significant shift from standard running data will initiate a LFG extraction infrastructure inspection / investigation. An LFG extraction infrastructure inspection / investigation (EIII) methodology is dependent upon the type of monitoring data deviation which occurs. Particular monitoring data deviations can strongly indicate where investigation of the infrastructure should commence. An EIII will commence with examination of the monitoring data to determine an EIII methodology, it would normally occur in the following manner;

1. Determine the extent and specific type of abnormality. 2. Determine possible areas of the extraction system from which it is possible for that type

of abnormality to originate. 3. List possible causes and remediation actions required. 4. List consumables / tools required. 5. List extraction system inspection locations from most to least likely to investigate. 6. Assemble consumables / tools and carry out EIII.

During weekly gas field well balancing checks, the gas field technician is on the alert for any LFG emissions from the areas of the waste cells traversed whilst undertaking this task. Visual and olfactory senses are important tools for the initial detection of surface egress of LFG. The detection can be confirmed through Flux Box Testing and decisions reached on requirements for remedial works such as cover repair and/or increasing the area of influence of those locations nearest LFG extraction well. Cell walk overs are undertaken at the site every sixteen (16) weeks in order to inspect areas of the cells not frequently traversed by the well field technician. Visual and olfactory senses are the primary tools used to detect any damage to the cell cover and/or LFG egress from the cell. Following detection of any cell cover deterioration or LFG egress, the well field technician will report the detection to the landfill site supervisor and liaise with the supervisor for remedial works to be undertaken.


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9. LFG CONTROL – POST COMMERCIAL UTILISATION

Post-commercial LFG utilisation activities, the City Cockburn will assume physical management of LFG control and monitoring. When it is no longer commercially viable to undertake LFG utilisation from the site, the LFG power station located at the HWRP will be decommissioned. All LFG extraction and flaring infrastructure will remain at the site post-power station decommissioning to enable continued LFG control and abatement activities. The City of Cockburn will undertake LFG control via the following mechanisms;

• Utilise retained existing LFG Extraction and Flaring Infrastructure for LFG control, monitoring and abatement activities.

• Undertake the development of a revised LFG monitoring and gas flaring plan.

• Undertake the development of an LFG infrastructure maintenance plan.

• Creation of in-house LFG operational management capability by undertaking appropriate training of City employees to a standard required for competent operation and monitoring of the LFG Extraction and Flaring Infrastructure.

• Alternatively the City may procure contract LFG management services from appropriately experienced private industry service providers.


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10. CONCEPTUAL SITE MODEL

10.1 Conceptual Site Model Overview

A conceptual site model is developed for a particular landfill site in order to identify sources of LFG, pathways by which LFG can migrate from the source and potential receptors of any LFG which has an identified pathway between the LFG source and the potential receptor (refer to figure 10.1).

10.2 Potential Sources of LFG

LFG may be generated from three main different processes - Bacterial Decomposition, Chemical Reactions and through Volatilization. The three main processes through which LFG generation can occur are explained below:

• Bacterial Decomposition – most LFG is produced via Methanogenesis which occurs whilst anaerobic conditions exist during the breakdown of organic material by microorganisms that are naturally present in the waste.

• Chemical Reactions – reactions of certain chemicals present in the waste may create LFG including non-methanogenic organic carbons (NMOCs).

• Volatilization – LFG may be created when certain waste types undergo volatilization, particularly organic compounds. NMOCs present in landfill gas may be the product of particular chemicals disposed of in the landfill.

The Henderson Waste Recovery Park has seven waste cells which have been designed and constructed with engineered liner systems and leachate collection & management infrastructure. All seven waste cells at the Henderson Waste Recovery Park are producing LFG. The seven cells are all identified sources of LFG at the site.

10.3 Potential Pathways

Potential pathways for LFG migration from the identified sources of LFG at the Henderson Waste Recovery Park are listed below:

• Direct release of LFG into the atmosphere from Landfill Gas Extraction Infrastructure.

• Direct release of LFG into the atmosphere from waste cell surface emission.

• Direct release of LFG into the atmosphere from Leachate Management infrastructure, including leachate pump pits & pipe exit points.

• Direct release of LFG into the atmosphere from release of dissolved LFG contained in leachate stored in leachate ponds.

• Direct release of LFG into the atmosphere from Landfill Gas Utilisation infrastructure.

• Accumulation of LFG within Leachate Management infrastructure from release of dissolved LFG contained in leachate within waste cells.

• Accumulation of LFG within Waste Transfer Station Infrastructure from waste cell surface emission.


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All waste deposited in the waste cells at the Site are contained within the boundary of engineered membrane liner systems which achieves separation of all deposited waste and leachates from the naturally occurring geology. Given the integrity of this system, lateral migration through the surrounding geology is not considered as a potential pathway.

10.4 Potential Receptors

The identified potential pathways for landfill gas migration from the identified landfill gas sources at the site is considered to be mainly potential direct release to the atmosphere from several sources. To a much lesser degree there is potential that accumulation of landfill gas could occur within specific Leachate Management Infrastructure and Waste Transfer Station Infrastructure. The main exposure is via inhalation of gases. Potential receptors are listed below:

• Employees and visitors to the site during cell excavation works.

• Employees and visitors within onsite buildings and infrastructure.

• Workers accessing leachate management and control infrastructure such as pump pits or submersible pumps.

• Workers and visitors at off-site properties.


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Figure 10.1 - Conceptual Site Layout


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11. LFG HAZARD ASSESMENT

11.1 LFG Composition

LFG produced from microbial breakdown of organic material is composed mainly of methane (CHh4) and carbon dioxide (CO2). LFG formed during steady state stage of methanogenis is usually found at the concentration ratio of 60% CH4 and 40% CO2. LFG can contain many trace gases and compounds including;

• Ammonia

• Siloxanes

• Sulphides

• Carbon Monoxide

• Nitrogen

• Oxygen

• NMOCs

• Hydrocarbons

• Mercaptans

Water vapour is always found in LFG. The water vapour, together with the numerous trace gases and compounds found within LFG, can pose a significant corrosion risk to LFG management and control infrastructure.

11.2 LFG Migration

Microbial breakdown of organic material within a landfill waste cell causes landfill gas to be generated within the cell. The generation of the LFG within the restricted confines of a waste cell will result in a small pressure differential between the LFG contained within the waste in the cell and the atmosphere surrounding the cell. This small pressure differential between cell and atmosphere will cause the LFG to flow away or migrate from the higher pressure zone of the waste cell to the lower pressure zone of the atmosphere. LFG can also migrate via diffusion, which is movement from a zone of higher concentration to a zone of lower concentration. In an unlined landfill waste cell, LFG being generated within the waste cell has the potential to migrate from the cell both laterally into any permeable surrounding geological formation and vertically in to the atmosphere. A synthetic membrane lined waste cell generally only has the potential for LFG to migrate through the top surface of the cell directly into the atmosphere. Both types of cell construction have the potential for LFG to migrate into any structures abutting on to the waste cell.


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11.3 Methane Hazard

Methane is a colourless, odourless, flammable gas which when it is in the concentration range of 5% to 15% mixed with air is explosive. The explosive concentration range of methane is termed the Lower Explosive Limit (LEL) at 5 % and the Upper Explosive Limit (UEL) at 15%, concentrations outside of this range is only flammable.

11.4 Carbon Dioxide Hazard

Carbon dioxide is a colourless, odourless and non-combustible gas. Toxic levels of carbon dioxide are typically above 5% concentration levels. Exposure to higher levels may cause unconsciousness or death within a short timeframe of exposure.

11.5 LFG Trace Gas Hazard

Some of the trace gases found in LFG are both toxic and flammable. It would, however, be unusual to find any of the trace gases associated with landfill gas near or above their respective lower explosive limit concentration, but rather in a “parts per million” range. Due to the presence of trace gases and various compounds, landfill gas has a unique and quite distinctive odour which is as easily recognisable as the odorant mixed into natural gas (100% methane).

11.6 Summary of LFG Hazards

LFG has numerous potential hazards which can present risks ranging from nuisance to life threatening. When dealing with LFG, appropriate measures and practices must be in place to ameliorate the potential risks that are associated with the hazards that are present from LFG. LFG hazards are summarized below:

• LFG should be viewed as a potential asphyxiate.

• LFG is a flammable substance.

• When LFG is in the 5% to 15% concentration range it should be viewed as having explosive capability.

• LFG should always be viewed as a potentially toxic substance.

• LFG has the potential to migrate from its source via both pressure differential and diffusion.

The identified risks of LFG include:

• Effects to human health.

• Damage to structures.

• Effects on human amenity.

• Effects to local habitat.


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11.7 LFG Control Measures

Managing LFG effectively is dependent upon the ability to prevent uncontrolled egress or migration of LFG into the environment. This is achieved by the collection and conveyance of the generated LFG to the desired treatment/utilisation technology in a reliable and safe manner on a continuous basis. Two main methods for LFG control are available:

• Passive/active collection with controlled venting to atmosphere.

• Active collection and extraction followed by controlled combustion. The method utilised at the Henderson Waste Recovery Park is active collection and extraction with controlled combustion. The LFG is actively influenced from the waste cells at the site via a network of extraction and reticulation pipework to a methane management compound. The landfill gas is then combusted within internal combustion engines and converted into electrical energy. If necessary, the landfill gas can also be combusted within an enclosed gas flaring system. Apart from planned outages such as maintenance requirements, or unplanned outages such as network faults, the LFG management system at the HWRP operates continuously. Historical operational availability of the installed LFG management system is extremely high, bordering on 100% (refer to figure 5.1). The high operational availability of the system is achieved through appropriate system design, preventative maintenance schedules and robust operational procedures.

11.8 Hazard Identification and Risk Ranking

In order to ensure that a reliable and safe LFG management system is operating at the site, potential hazards associated with the sources of landfill gas at the site or from the operation of landfill gas management systems need to be identified. Hazards and receptors are identified through the development of a conceptual site model. Identified hazards are assessed as to what levels of risk they pose to potential receptors. A risk matrix will determine a risk ranking for the levels of risk posed. A risk ranking determines how that particular risk is managed. The application of various levels of risk control mechanisms needs to be applied to unacceptable risks in order to change a high risk ranking to a lower ranking Listed below are tables for Risk Matrix, Risk Consequence, Risk likelihood and Risk Rankings. Appling Consequence and Likelihood category across the Risk Matrix will provide a Risk category. Actions required to manage the particular category of risk is determined from the Risk Ranking table.


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Risk Matrix

Consequence A Almost Certain

B Likely

C Probable

D Unlikely

E Rare

1 Severe Very High Risk Very High Risk Very High Risk Very High Risk High

2 Significant Very High Risk Very High Risk Very High Risk High High

3 Moderate Very High Risk High High Moderate Moderate

4 Minor High High Moderate Low Low

5 Negligible High Moderate Low Low Low

Consequence Descriptions Level Consequence Interpretation

1 Severe Death, Operations cause catastrophic offsite impacts immense financial loss

2 Significant Extensive injuries or illness, hospitalisation required, operations cause substantial offsite impacts and major financial loss.

3 Moderate Some health impacts to humans, some offsite temporary impacts and large financial loss.

4 Minor First aid required, minimal offsite impacts, small financial loss.

5 Negligible No health impacts, negligible impacts negative financial loss.

Likelihood Categories Level Consequence Interpretation

1 Almost Certain Is expected to occur almost all of the time.

2 Likely Is expected to occur most of the time.

3 Probable Might occur.

4 Unlikely Might occur but is not expected.

5 Rare This event may only occur in exceptional circumstances.

Risk Ranking Category Action

Low Managed by routine procedures in place.

Moderate Managed by specific monitoring or procedures with responsibility specified

High

Senior management attention required, action plans developed and responsibility specified.

Very High Senior management attention required, action plans developed, responsibility specified and urgent response.

Table 11.1 Risk Rating Tables


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APPENDIX A LFG HAZARD ASSEMENT TABLES A1 – A15 The following tables A1 through to A15 provide Risk Ratings for identified LFG Hazards and the current controls in place to manage the potential risks from these hazards.

TABLE A1 LFG HAZARD ASSESMENT – SOURCE 1 HAZARD ASSESSED: Direct Release of LFG to Atmosphere HAZARD SOURCE: Through Uncapped Landfill Surface Risk Assessment Factors: - LFG being generated beneath current waste bench.

- High traffic area. - Active LFG extraction occurring below current waste bench. - Reduced extraction efficiency due to air ingress risk. - Emissions readily identified by LFG odour

Likelihood: Likely Consequence: Moderate Receptor: Onsite workers and visitors, Onsite odour issues. Hazard: Human health, explosion risk, odour, fire. Risk Rating No Controls: High Current Controls:

• Placement of daily cover on waste and intermediate cover on cell batter walls.

• Horizontal gas extraction well ongoing placement six (6) metres below cell working area.

• Initial daily monitoring of activated extraction wells, upon balanced extraction well operation - extend monitoring to weekly.

• Cell working area walkover weekly with portable gas detector. (WGR)

• No naked flames allowed, no smoking area.

• Hot work permit system, only to be issued if absolutely required to undertake hot work on the cell. (HWRP)

• Onsite cell fire plan in place. Residual Risk Rating with Controls:

• Low


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TABLE A2 LFG HAZARD ASSESMENT – SOURCE 2 HAZARD ASSESSED: Direct Release of LFG to Atmosphere HAZARD SOURCE: Through Intermediate and Final Capped Area of Cells Risk Assessment Factors: - Wind/rain erosion of cell capping material.

- Cracking of cell capping material. - Penetrations into cell capping by burrowing animals and insects. - Damage to cell capping via waste subsidence. - All waste cells under active gas extraction.

Likelihood: Probable Consequence: Moderate Receptor: Onsite workers, offsite odour issues, and visitors Hazard: Potential human health, odour, fire risk Risk Rating No Controls: High Current Controls:

• All cells have gas extraction infrastructure installed.

• All cells under active gas extraction.

• All cells maintained at balanced extraction operation levels.

• Cell odour identification undertaken during weekly gas monitoring, any odour identification would initialise an EII cell inspection.

• Cell walkover undertaken every sixteen weeks to check integrity of cell intermediate cover (HWRP).

• Onsite fire plan in place. Residual Risk Rating with Controls:

• Low


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TABLE A3 LFG HAZARD ASSESMENT – SOURCE 3 HAZARD ASSESSED: Direct Release of LFG to Atmosphere HAZARD SOURCE: LFG Extraction Infrastructure Risk Assessment Factors: - Extraction infrastructure corrosion susceptibility

- Extraction piping construction reliability. - System operational basis. - System operating pressures. - System inspection schedules. - Reticulation piping expansion/contraction is temperature variable. - Is extraction infrastructure clearly identifiable over whole site?

Likelihood: Probable Consequence: Moderate Receptor: Onsite workers and visitors, offsite odour issues Hazard: Potential human health, odour, fire risk Risk Rating No Controls: High Current Controls:

• Non corrosive and plastic welded components used in system to eliminate corrosion failure in the extraction system.

• Gas extraction infrastructure is painted white to allow clear identification of system and to reduce expansion/contraction of pipe work from temperature variations.

• Complete extraction system is operated at negative pressure, in the event of unintentional/ intentional damage, system won’t leak to atmosphere whilst operational.

• Power station engine management system will detect any large deviation in extracted gas quality and raise an alarm status.

• Alarm status from system is monitored and will send alarm message to duty manager of power station for attendance.

• Operational target for extraction operation is continuous.

• Weekly inspections of gas extraction infrastructure is undertaken to ensure that the integrity of the system hasn’t been or is not at risk of compromise.

• Scheduled maintenance is undertaken on Extraction Infrastructure. Residual Risk Rating with Controls:

• Low


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TABLE A4 LFG HAZARD ASSESMENT – SOURCE 4 HAZARD ASSESED: Direct Release of LFG to Atmosphere HAZARD SOURCE: Sealed Capping Layer of Transfer Station Risk Assessment factors: - High traffic area.

- LFG being generated below sealed capping layer of Transfer Station.

- Potential cracking of sealed capping layer. - Potential damage to sealed capping layer via waste subsidence. - Potential erosion of sealed capping layer. - Depth and type of sealed capping layer. - Transfer station area under active LFG extraction. - LFG emissions readily identifiable by odour.

Likelihood: Unlikely Consequence: Moderate Receptor: Onsite workers and visitors Hazard: Human health, explosion risk, fire risk, site odour Risk Rating No Controls: Moderate Current Controls:

• LFG extraction wells installed under sealed capping.

• Transfer Station area under active LFG extraction.

• No smoking/no naked flame area.

• Weekly walk over surface inspection.

• Hazard and safety signage.

• Staff odour detection reporting procedure.

• 5 kilometres per hour speed limit within Transfer Station.

• Survey and record in a log monthly on capping integrity and erosion. (HWRP) Residual Risk Rating with Controls:

• Low


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TABLE A5 LFG HAZARD ASSESMENT – SOURCE 5 HAZARD ASSESSED: Direct Release of LFG to Atmosphere HAZARD SOURCE: From LFG Utilisation Equipment Risk Assessment Factors - System operating history of incidents of LFG release to atmosphere.

- Gas leak detection system characteristics. - Automated gas isolation availability and type. - Type of manual gas supply isolation available. - Scheduled system maintenance in place. - Utilisation equipment suitability for operation on LFG.

Likelihood: Unlikely Consequence: Moderate Receptor: Onsite workers and visitors, infrastructure, offsite odour issues Hazard: Human health, explosion, fire, infrastructure damage Risk Rating No Controls: Moderate Current Controls:

• Planned and scheduled maintenance to equipment exceeding OEM specifications.

• Utilisation equipment operates under fail safe monitoring.

• Failsafe isolation of gas supply to utilisation equipment when non-operational.

• OEM gas detection systems fitted to utilisation equipment housing on failsafe loop.

• Remote alarm messaging and remote monitoring of facility.

• Simple manual isolation of extraction system within compound.

• Simple manual isolation of gas extraction system outside of compound.

• Single E stop located in facility compound will shut down and black out entire facility. Residual Risk Rating with Controls:

• Low


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TABLE A6 LFG HAZARD ASSESMENT – SOURCE 6 HAZARD ASSESSED: Direct Release of LFG to Atmosphere HAZARD SOURCE: From LFG Gas Flare Risk Assessment Factors: - Equipment operation modes.

- Failsafe auto gas supply isolation on shutdown. - Equipment remote monitoring/alarm capacity. - Manual gas isolation availability. - Is Flare system purpose designed for operation on LFG?

Likelihood: Unlikely Consequence: Moderate Receptor: Onsite workers and visitors, offsite odour issues Hazard: Human health, explosion risk, odour, fire Risk Rating No Controls: Moderate Current Controls:

• Equipment can only operate in failsafe condition.

• Equipment can only be put into operation or restarted manually by operator attendance.

• Equipment manually isolated from gas supply when not in operation.

• When in operation equipment is remotely monitored for failure.

• Gas flare fitted with anti-flashback device.

• Upon active alarm status, blower shutdown and auto isolation from gas supply.

• Daily operation inspection when in operation. Residual Risk Rating with controls:

• Low


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TABLE A7 LFG HAZARD ASSESMENT – SOURCE 7 HAZARD ASSESSED: Direct Release of LFG to Atmosphere HAZARD SOURCE: From Prolonged Failure of LFG Extraction Infrastructure Risk Assessment Factors: - System failure susceptibility from corrosion impacts.

- Preventative maintenance schedule requirements - System inspection. - Fire risks over entire system. - Availability of pipe, fittings and system components. - Availability of system installation, welding and repair services. - Individual extraction wells capacity to increase area of influence.

Likelihood: Rare Consequence: Moderate Receptor: Onsite workers and visitors, offsite odour issues, potential risk to onsite infrastructure Hazard: Human health, amenity of surrounding land, fire risk, odour, effects on flora and fauna Risk Rating No Controls: Moderate Current Controls:

• Preventative maintenance and inspection schedules in place.

• All extraction piping painted white for clear identification.

• Fire breaks installed and maintained over entire system.

• Maintain in house system installation & welding and repair capability.

• Maintain system parts inventory.

• System constructed from non-corrosive materials.

• Extraction system locations are surveyed onto a plan. Residual Risk Rating with Controls:

• Low


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TABLE A8 LFG HAZARD ASSESMENT – SOURCE 8 HAZARD ASSESSED: Direct Release of LFG to Atmosphere

HAZARD SOURCE: Prolonged Failure of Utilisation System Risk Assessment Factors: - Utilisation system redundancy & reliability.

- Gas extraction and fuel supply system redundancy & reliability. - Backup independent LFG extraction/flaring reliability. - Redundancy of network feeder entry point. - Can system operate independent of electricity network? - Historic prolonged outage of utilisation equipment or network. - Are adequate maintenance schedules in place?

Likelihood: Rare Consequence: Moderate Receptor: Onsite workers and visitors, offsite odour issues, potential risk to onsite infrastructure. Hazard: Human health, amenity of surrounding land, odour, effects on flora and fauna. Risk Rating No Controls: Moderate Current Controls:

• Each generator module fuel supply from independent LFG extraction and processing units.

• Utilisation equipment is made up of three independent operable units.

• System contains independently operated LFG extraction and combustion flare.

• Generator modules are maintained to OEM maintenance schedules.

• Maintenance schedules additional to OEM scheduled requirements implemented to further improve unscheduled outages and module performance.

• Critical spare parts inventory held on site.

• Scheduled maintenance and inspection undertaken to balance of plant.

• Critical balance of plant spare parts inventory held on site.

• Facility has two (2) separate network feeder points for network access.

• Fire breaks installed and maintained around facility compound.

• Failsafe isolation of gas supply to generator modules upon shutdown.

• System can operate independent of network via generator load banks. Residual Risk with Controls:

• Low


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TABLE A9 LFG HAZARD ASSESMENT – SOURCE 9 HAZARD ASSESSED: Direct Release of LFG to Atmosphere HAZARD SOURCE: From Leachate Storage Pond Risk Assessment Factors: - Only small amount of LFG can be dissolved into leachate.

- Walk around inspections of pond has not revealed detectable concentrations of LFG.

- Pond is completely open to atmosphere.

Likelihood: Rare Consequence: Minor Receptor: Onsite workers, onsite odour Hazard: Human health, site amenity Risk Rating No Controls: Low Current Controls:

• Weekly walk around, check for LFG odour. (HWRP)

• If LFG odour detected, test for LFG in air inside pond walls. (HWRP)

• If methane levels ˃ 25% of LEL concentrations detected review control actions. (HWRP)

• Create Log to record above inspections and actions. (HWRP)

Residual Risk Rating with Controls:

• Low


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TABLE A10 LFG HAZARD ASSESMENT – SOURCE 10 HAZARD ASSESSED: LFG ACCUMALATION WITHIN LEACHATE INFRASTRUCTURE HAZARD SOURCE: CELL 4 LEACHATE PUMP PIT Risk Assessment Factors: - Residual leachate level in waste cell base provides effective seal between LFG and pump pit interior.

- Accumulation of LFG in pump pit may occur from disassociation of dissolved gases in leachate.

- Methane levels detected in pump pit from monitoring measurements <20% LEL concentration.

Likelihood: Likely Consequence: Moderate Receptor: Onsite workers, contract workers, infrastructure. Hazard: Human health, explosion risk, infrastructure damage. Risk Rating No Controls: High Current Controls:

• Monitor monthly for exceedance of ˃75% of LEL concentrates within pump pit. (HWRP)

• Create Log to record inspections and actions. (HWRP)

• Specified plan for any maintenance works. (HWRP to create JSA)

• Confined space entry permit and specific works system. (HWRP)

• Review controls if ˃75% LEL concentrations detected.

• Create hazard sign – No works are permitted on this pit until all permits are obtained.

(HWRP)

Residual Risk Rating with Controls:

• Moderate


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TABLE A11 LFG HAZARD ASSESMENT – SOURCE 11 HAZARD ASSESSED: LFG Accumulation within Leachate Infrastructure HAZARD SOURCE: Cell 5 Submersible Pump Housing Shaft Risk Assessment Factors: - Residual leachate level in waste cell base provides an effective seal between LFG and pump shaft.

- Accumulation of LFG in pump shaft may occur from disassociation of dissolved gases in leachate.

- No LFG detected in pump shaft from monitoring tests. Likelihood Likely Consequence: Moderate Receptor: Onsite workers, contract workers, infrastructure. Hazard: Human health, explosion risk, infrastructure damage. Risk Rating No Controls: High Current Controls:

• Monitor monthly for exceedance of ˃75% of LEL concentrates within shaft. (HWRP)

• Specified plan for any maintenance works. (HWRP)

• Review controls if > 75% LEL concentrations detected. (HWRP) Residual Risk Rating with Controls:

• Moderate


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TABLE A12 LFG HAZARD ASSESMENT – SOURCE 12 HAZARD ASSESSED: LFG Accumulation in Leachate Infrastructure HAZARD SOURCE: 1, 2, & 3 Submersible Pump Housing Shaft Risk Assessment Factors: - Residual leachate level in waste cell base provides effective seal between LFG and pump shaft.

- Accumulation of LFG in pump shaft may occur from disassociation of dissolved gases in leachate.

- No methane detected in pump shaft from monitoring tests. Likelihood: Probable Consequence: Moderate Receptor: Onsite workers, contract workers, infrastructure. Hazard: Human health, explosion risk, infrastructure damage. Risk Rating No Controls: High Current Controls:


• Specified plan for any maintenance work. (HWRP)

• Review controls if ˃75% LEL concentrations detected. (HWRP) Residual Risk Rating with Controls:

• Moderate


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TABLE A13 LFG HAZARD ASSESMENT – SOURCE 13 HAZARD ASSESSED: LFG Accumulation in Leachate Infrastructure HAZARD SOURCE: Cell 6 Submersible Pump Housing Shaft Risk Assessment Factors: - Residual leachate level in waste cell base provides an effective seal between LFG and the pump shaft.

- Accumulation of LFG in the pump shaft may occur from disassociation of dissolved gases in leachate.

- No methane detected in pump shaft from monitoring tests. Likelihood: Probable Consequence: Moderate Receptor: Onsite workers, contract workers, infrastructure. Hazard: Human health, explosion risk, infrastructure damage. Risk Rating No Controls: High Current Controls:



• Review controls if ˃75% LEL concentrations detected. (HWRP) Residual Risk Rating with Controls:

• Moderate


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TABLE A14 LFG HAZARD ASSESMENT – SOURCE 14 HAZARD ASSESSED: Accumulation of LFG in Leachate Infrastructure HAZARD SOURCE: Cell 7 Submersible Pump Housing Shaft Risk Assessment Factors: - Residual leachate level in waste cell base provides an effective seal between LFG and pump shaft.

- Accumulation of LFG in the pump shaft may occur from disassociation of dissolved gases in the leachate.

- No LFG detected in pump shaft from monitoring tests.

Likelihood: Probable Consequence: Moderate Receptor: Onsite workers, contract workers, infrastructure Hazard: Human health, explosion risk, infrastructure damage Risk Rating No Controls: High Current Controls:



• Review controls if ˃75% LEL concentrations detected HWRP). Residual Risk Rating with Controls:

• Moderate


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TABLE A15 LFG HAZARD ASSESMENT – SOURCE 15 HAZARD ASSESED: LFG Accumulation within Transfer Station Infrastructure HAZARD SOURCE: Portable Gate House, Sea container and Hook Lift Bins Risk Assessment Factors: - LFG being generated beneath sealed capping of Transfer Station. - Cracking of sealed capping layer under infrastructure. - Damage to sealed capping layer under infrastructure via waste subsidence. - Damage to sealed capping layer under infrastructure via Burrowing animals and reptiles - Depth of sealed capping layer. - The propensity of the infrastructure to trap LFG within an enclosed space. - Area under active LFG extraction. - Emissions readily identified by LFG odour. Likelihood: Probable Consequence: Moderate Receptor: Onsite workers and visitors Hazard: Human health, explosion risk, fire risk, onsite odour Risk Rating No Controls: High Current Controls:

• LFG extraction wells installed under sealed area.

• Transfer station area under active LFG extraction.

• Flammable gas LEL monitor fitted in portable gate house, containers and bins. (HWRP)

• No smoking/no naked flame area.

• Hazard and safety signage. (HWRP)

• Staff odour detection reporting procedure.

• Monthly portable gas analyser monitoring of sea container and hook bins. (HWRP)

• Record monitoring result in Log book. (HWRP) Residual Risk Rating With Controls:

• Low


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TABLE A15 LFG HAZARD ASSESMENT – SOURCE 16 HAZARD ASSESED: Transformer Fire in Utilisation Equipment HAZARD SOURCE: Transformer overheating Risk Assessment Factors: - Low fluid in transformer. - Blocked oil flow in radiators. - Shut radiator banks. - Eddy current heating of the tank. - Overheating tap changer contacts. - Loos connections at bushing terminals. - Moisture contamination of surge arrestors. Likelihood: Rare Consequence: Minor Receptor: Onsite workers, contract workers, infrastructure. Hazard: Fire risk, infrastructure damage. Risk Rating No Controls: Low Current Controls:

Existing Risk Controls In Place – Transformers

• Insulation Testing – 10,000 hour intervals.

• Visual Inspection of HV/LV Bushing/Terminations -10,000 hour intervals.

• Check all Cable Termination Nut Tensions – 10,000 hour intervals. Transformer Automated Protection Controls in Place

• Oil Temperature Instruments.

• Oil Level Instruments.

• Vacuum Measurements within Transformer.

• Over-Pressure Rupture Disk Monitor. A Site Risk Report for the Methane Management Compound was conducted in October 2013 by RMRI.

13.02 recommended that thermographic scanning on all transformers be conducted. This was considered

unnecessary by WGR’s Consulting Electrical Engineer as follows:

Site work procedures require that prior to any works or inspections of the 415v to 22kv transformers are

undertaken they must be de-energised and racked to earth. A thermographic scan requires the transformer

to be at load at operating temperature with both High and Low Voltage bushing/cable termination

compartments open for scanning of cable terminations & bushes. This is considered by Waste Gas

Resources as a high risk procedure which does not align with safe work procedures.

Existing risk control mechanisms in place for inspection and maintenance are adequate. In addition the

transformers duty rating by virtue of the original design parameters of the facility is 33% higher than actual

operating duty for the transformers. The Transformers also have monitoring and protection on the HV and

LV side for over-current and earth faults within the network. All transformers are also fitted with visual oil

level and oil temperature gauges. Additionally, the level of automated transformer monitoring and

protection controls is specifically targeted at overheating and insulating fluid degradation or loss.

Residual Risk Rating With Controls:

• Low


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APPENDIX B EXTRACTION WELL LOCATION PLANS TABLE B1 – B9 The following tables provide survey locations of horizontal and vertical landfill gas extraction wells installed at the Henderson Waste Recovery Park.


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Henderson Recovery Park TABLE B1 CELL 2 VERTICAL GAS EXTRACTION WELL PLAN


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Henderson Recovery Park TABLE B2 CELL 4 HORIZONTAL GAS EXTRACTION WELL PLAN RL 14


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Henderson Recovery Park TABLE B3 CELL 3 VERTICAL GAS EXTRACTION WELL PLAN


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Henderson Recovery Park TABLE B4 CELL 4 & 5 VERTICAL GAS EXTRACTION WELL PLAN


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Henderson Recovery Park

TABLE B5 CELL 6 HORIZONTAL GAS EXTRACTION WELL PLAN RL 12 & 13


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Henderson Recovery Park TABLE B6 CELL 6 HORIZONTAL GAS EXTRACTION WELL PLAN RL 16


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TABLE B7 CELL 6 HORIZONTAL GAS EXTRACTION WELL PLAN RL 27


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