Tunnelling in Australia is booming and a vital part of key infrastructure projects designed to reduce congestion in urban areas. Approximately 66% of the global population is projected to be living in cities by 2050. Demands on transportation indicate tunnelling engineering has got a strategic role to play in the construction of sustainable urban areas across the World. However, excavation work required in or near tunnels is considered ‘high risk’ under the Workplace Health and Safety Regulations and is a primary concern within the construction industry.

Tunnel construction workers have an increased risk of developing silicosis, chronic obstructive pulmonary disease (COPD), adverse respiratory symptoms, double the rate of lung function decline than heavy smokers, asthma, general airflow limitation, and lung cancer, and thus represent a high-risk work group [1,2,3,4]. At last week’s Australian Tunnelling Conference in Sydney, these finding were highlighted by Kate Cole. [5]

Ventilation design is a key component of any tunnel construction project. Tunnels must be well ventilated to enable workers to carry out work without risk to health and safety. Ventilation design must ensure there are no dead spots, no low air speed areas, no flow reversals, no areas of dust concentration, no recirculation and inspection points fitted where blockages are likely to occur. [6].

Controlling dust and fumes often requires a combination of control measures to be implemented and will vary depending on the extraction method and site conditions. Control measures may contain dust suppression, air filtration and scrubber units, water sprays and dust suppression on conveyor belts. [6]

Grydale developed a ventilation system design for the major infrastructure project in Melbourne, that offers a complete exhaust system that removes contaminants from the tunnel at the tunnel face and also supplies fresh clean air for Civil, Mechanical and Electrical works. The design was created in-house using VentsimTM DESIGN 5, and is separated into 13 stages, representing the tunnel area changes. The design utilises up to two scrubbers for each stage, with additional axial fans to boost airflow when major excavation works are complete.

The Grydale range of mobile dust collectors / tunnel scrubbers enable this alternative approach to ventilation design from 10m³ units to 60m³. We believe that extracting dust at source should become best practice within tunnelling projects and work in conjunction with the overall ventilation plan. Our mobile machines are able to track closely to excavation machinery to remove dust and contaminants at source.

Removing dust at source reduces the impact on air flow within the tunnel and on operators working along the length of the tunnel. It reduces the number of machines required in the confined space – reducing risk and operational costs.

The following features are standard on the JMS M-Series Track Dust Collectors and are key to ensuring Workplace Health and Safety regulations are maintained:

Track Mounting

• Grydale hold the patent for manufacturing the only self-propelled dust extractor on the market. Track mounting offers full mobility and better control alongside excavation machinery.

Single / Dual Intake Drop Out Box

• Machines can be manufactured with either a single or dual intake depending on extraction processes.
• The patented designed drop-out box takes the majority of heavy dust particles out of the air stream as dirty air enters the scrubber. This allows the machine to handle extreme dust loading and achieve a filtration efficiency of 99.99% at 0.067 micron particle size.

Volvo Penta T4F Diesel Engine

• Using Volvo Penta T4F engines ensures we are meeting the highest emission standards in the world along with providing world class fuel efficiency.

Variable Dust Loading

• Machines are highly versatile and offer variable air flow control so can be used as a ventilation machine – where dust loading is significantly lower (1 tonnes per day) or can get up close to excavation machinery with a higher dust loading (1 – 1.5 tonnes of airborne dust per hour).

Real-Time Emission Monitoring

• Real-time particle detectors can be programmed to meet site specific regulations and ‘alarm’ when levels are being approached so operators can proactively manage risks and exposure to contaminants.

Grydale JMS M-Series dust collectors have already been deployed to work in high profile tunnelling projects in Sydney and Melbourne.

At Grydale we are committed to innovation and improvement to ensure we are not only driving forward excellence, producing efficient solutions to industrial dust and fume problems and increasing operator and environmental safety.

For more information on our range of Dust Collectors or to speak to us about how we can help with ventilation design or purchase / rental of dust collection machinery please contact enquiries@grydale.com.au

References:

[1] B. e. a. Ulvestad, “Increased risk of obstructive pulmonary disease in tunnel workers,” Thorax, pp. 277 282, 2000.

[2] L. M. B. B. D. P. K. J. B. J. Ulvestad B, “Gas and dust exposure in underground construction is associated with signs of airway inflammation,” European Respiratory Journal, vol. 17, pp. 416-421, 2001.

[3] B. B. E. W. K. J. L. M. Ulvestad B, “Cumulative exposure to dust causes accelerated decline in lung function in tunnel workers,” Occupational and Environmental Medicine, vol. 58, no. 10, pp. 663-669, 2001.

[4] M. E. F. P. Ulvestad B, “Asthma in tunnel workers exposed to synthetic resins,” Sand J Work Environ Health, vol. 25, no. 4, pp. 335-341, 1999.

[5] Investigating best practice to prevent illness and disease in tunnel construction workers Kate Cole, 2016 Churchill Fellow

[6] Safe Work Australia Guide for Tunnelling, November 2013