Confined space bowtie risk assessment framework for sewerage treatment plant in construction project

Abstract

The Langat Sewerage Treatment Plant (STP) project, which covers a 60.9 sq km catchment area starting from Cheras Batu 11 to Kajang, is a state-of-the-art and modern facility. The STP will be equipped with green technology initiatives and public facilities which can accommodate sewerage inflow around 207,000 m3 per day or 920,000 population equivalent (PE). The purpose of this research is to investigate the issues related to safe working in confined spaces at sewerage treatment plant construction project in Hulu Langat district and to provide a solution by proposing a substantial approach in mitigating risk during confined space entry due to an ineffective risk assessment and poor compliance by project management. Since 2010, the Department of Occupational Safety and Health Malaysia has recorded numerous fatal confined space accidents, in which the main contributing factors are attributed to leadership, permit to work, risk assessment, competency, tool and equipment, as well as safe work procedure. Several Malaysia and international safety requirements have been reviewed to contribute to confined space improvement opportunities, such as legislations, standards, guidelines, and industrial codes of practice. This research proposed for the Bowtie Risk Assessment graphical framework of confined space to be implemented at the sewerage treatment plant construction project in the Hulu Langat district. The methods used were through site visit observation and survey, followed by an analysis process of the selected risk assessment method. The site visit to the sewerage treatment plant project investigated the compliance of confined space risk assessment documents to established requirements such OSHA 1994, FMA 1967, ICOP 2010, HIRARC Guidelines 2008, Quebec Regulation 2015, ISO 31010, HSE UK, and BCGA UK. The selected risk assessment method was analysed with Bowtie Risk Assessment by referring to the preventive approach concept or barrier analysis. Next, additional information relevant to risk assessment from journals was included. Evaluation of Bowtie Risk Assessment was conducted through a focus group discussion (FGD), which plays an essential role in developing the Bowtie risk assessment graphical framework. The rationale for applying Bowtie Risk Assessment was based on its reliable technique, comprehensiveness, and graphical presentation. Finalization of the inputs provided by FGD was carried out with Bowtie specialists to ensure the quality of the developed framework. The outcomes from the Bowtie Risk Assessment provided a total output that generated 11 Threats with 39 Preventive Barriers and 10 Consequences with 29 Mitigation Barriers. The proposed Bowtie Risk Assessment graphical framework provides a sewerage treatment plant construction project with a holistic technique in preventing confined space accidents. It also provides a safe work system, manages hazards and risks effectively, promotes a good leadership practice, improves company reputation, and significantly reduces accident costs. The framework is also useful as a reference model to other industry players.