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Newsletter February 2021, Vol 002, Issue 01: Article

 

 

Fire Safety and Waste Management Facilities - Common Issues Encountered in the Industry

by: Srinath Iyengar

 

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Figure 1 - Photograph of typical waste pile within a waste sorting facility.

 

Introduction

The Federal Government introduced the Recycling and Waste Reduction Act 2020 1 in early December 2020, banning the export of unprocessed waste overseas. This legislation is expected to provide a stimulus to reconfigure local infrastructure to reprocess and re-manufacture recyclables onshore in Australia. This article sheds light on fire safety considerations for the growing number of waste management facilities being established around Australia.

1Recycling and Waste Reduction Bill 2020

Waste Management and treatment Facilities (WMF) come in various shapes and sizes each processing different types of waste products ranging from household chemicals to organic waste. The nature of these facilities and the materials stored within present unique set of risks in relation to site and building fire safety.

WMF Operational Mode

It is noted that there is no pre-defined classification for WMFs in the Building Code of Australia (BCA). However, there are typically two (2) building classifications that capture facilities namely: (i) Class 7b warehouse for waste storage and handling; or (ii) Class 8 industrial plant for waste sorting, processing and treatment. Some WMFs have a combination of Class 7b and Class 8 use with implications for occupant life safety and fire brigade intervention.

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Figure 2 - Sorted timber waste at a waste management facility awaiting collection.

WMFs may also operate on the basis of exclusively accepting certain waste streams, such as chemical waste, paints, solvents and e-waste products. Such facilities present a further unique set of risks where both the building and process risk needs consideration along with installed fire services.

BCA Considerations for WMFs

It is noted that there is no pre-defined classification for WMFs in the Building Code of Australia (BCA). However, there are typically two (2) building classifications that capture facilities namely: (i) Class 7b warehouse for waste storage and handling; or (ii) Class 8 industrial plant for waste sorting, processing and treatment. Some WMFs have a combination of Class 7b and Class 8 use with implications for occupant life safety and fire brigade intervention.

Many WMFs typically encompass long-span single storey warehousing buildings. Type C Construction, the least fire resistant construction under the BCA Deemed-to-Satisfy (DtS) Provisions can be readily applied but compartment size limitations restrict sizes to a maximum floor area of 2,000 m2 and volume of 12,000 m3. These limitations can be surpassed by applying Type A or Type B construction or applying Large-isolated Building provisions under BCA C2.3 as provided in the excerpt in Figure 3.

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Figure 3 - Extract from National Construction Code Building Code of Australia 2019 Volume 1 Amendment 1.

 

Large-isolated Building provisions trigger other requirements like sprinkler protection, smoke hazard management and perimeter vehicle access for fire brigade appliances. This can pose design challenges especially for existing facilities. However, a performance based fire engineered approach can provide an avenue to address the latter.

Fire and Rescue NSW (FRNSW) Guideline

Due to the recent fire incidents at WMFs and the potential for undetected fires to rapidly escalate within waste stockpiles, FRNSW has published a guideline for fire safety in waste facilities (FRNSW 2020). The objective being to address the various regulatory requirements for WMFs using information gathered from first-hand fire-fighting and operator experience in NSW and other jurisdictions in Australia.

The FRNSW Guide provides explanatory direction on common fire safety considerations during WMF design, some of which are discussed below:

Consideration 1: Waste Stockpile Fire Hazard

There are two causes for concern here, firstly there is a potential for certain waste products to self-heat and as such ignite materials around it. Such fires could potentially be deep seated within the stockpile making fire detection and intervention difficult.

To assist with firefighting operations, the FRNSW Guideline recommends that the maximum stockpile height should be no more than 4 m. Furthermore, in a fire situation attending firefighters would utilise the onsite equipment (excavators and the like) to relocate stockpiles that are stored within enclosed areas.

This allows Fire Safety Engineers to make informed decisions regarding maximum stockpile heights, face angles and isolation distances to minimise the potential fire spread between stockpiles.

Consideration 2: Fire Detection Efficacy

The environment within the building has a significant impact on the fire detection system proposed in a WMF. Typically, the environment within a WMF is dependent upon the waste material being processed or stored often leading to a dusty environment, air-borne particles or debris all of which can cause false fire alarms. Furthermore, vehicle emissions from garbage trucks and on-site material handling vehicles e.g., excavators or front loaders, also impact on the efficacy of fire detection systems. Hence, careful consideration is required. Hence, there can be design challenges with the efficacy of conventional fire detection and newer technologies like thermal imaging, flame detection or video smoke detection are possible solutions. However, these newer solutions may require site specific customised design, testing and monitoring to provide a reliable means of fire detection in WMFs

Consideration 3: Smoke Hazard Management

The building geometry, internal wall layouts, roof ventilation design, make-up air provisions and spatial configuration of respective sorting machinery greatly impact on the smoke management strategy within the building. Often the building is designed as a shell with the internal configuration an after-thought. Understanding the internal spatial design of the building during operation is critical for the development of a robust fire safety strategy for a WMF. A detailed Computational Fluid Dynamics (CFD) smoke model of various operational modes during the life of the building is a valuable design tool to enable the Fire Engineer and other design team members to address occupant evacuation and fire brigade intervention to meet BCA Performance Requirements.

Tailor-made Site-Specific Fire Design

A holistic performance-based fire safety strategy is essential to address BCA Performance Requirements and FRNSW Operational Requirements for modern WMFs. The management of waste stockpiles in relation to fire hazard, fire detection efficacy and smoke hazard are some of the key considerations for WMF fire safety design. A 'tailor-made' site specific fire engineering approach is recommended for each WMF considering the processing/ treatment functions being undertaken, intended various operational modes and the type of waste being processed/ stored.

References

FRNSW (2020), 'Fire safety in waste facilities', FRN14/3255 D17/81582 Version 2.02, available on: https://www.fire.nsw.gov.au/gallery/files/pdf/guidelines/guidelines_fire_safety_in_waste_facilities.pdf Last accessed on 28 Jan 2021.

UTS (2020), 'Australia's waste export ban becomes law', available on: https://www.uts.edu.au/news/social-justice-sustainability/australias-waste-export-ban-becomes-law Last accessed on 28 Jan 2021.

Waste Contractors and Recyclers Association of NSW (2019), available on: http://wcra.com.au/ Last accessed on 28 Jan 2021.

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