Case Study: Silica Control for Basement Shotcreting, NSW

Control Hire designed a ventilation and filtration system for a client's basement shotcreting works, sectioning the basement, sweeping clean air across the work zone and fitting each worker with a personal dust monitor to prove exposure was controlled.

Control Hire

Overview

The client had two crews of six shotcreting in the basement of a development in NSW, covering 50 to 60m² per day. The site was under close safety scrutiny and the stage had to finish on time.

The crews already had PPE in place. The client asked Control Hire to help control the silica risk and explain the changes to silica exposure requirements.

The Risk

Shotcreting releases high levels of Respirable Crystalline Silica (RCS). In a confined basement with little airflow, the dust stays trapped around the twelve workers. PPE is the last line of defence under the hierarchy of controls, so ventilation and filtration were needed as well.

RCS exposure can cause silicosis and other serious lung disease. With Australia moving from Workplace Exposure Standards (WES) to Workplace Exposure Limits (WEL), businesses have a legal duty to keep worker exposure below the limit. Falling short can mean SafeWork fines, more frequent inspections, being seen as a high risk contractor when tendering, and workers feeling their safety is not being looked after.

Solution

Control Hire’s engineers sectioned off the basement with a brattice style wall to contain the hazard. They then calculated the volume of each section and the air changes per hour required to keep workers safe.

1000mm axial fans with silencers were installed at one end of the space and 15,000m³/hr air scrubbers at the other. The fans push air across the work zone toward the scrubbers, sweeping dust away from the crews. The scrubbers use HEPA filters that remove 99.97% of particulate matter from the air.

To prove the controls were working and check for leakage, each worker was fitted with a personal dust monitor to record their silica exposure throughout the shift.