A management system for protecting compressed air tunnelling workers during operations through contaminated soil.

Manual excavation of a two-metre diameter sewer tunnel was carried out through ground contaminated by volatile organic compounds (VOCs) including benzene, toluene and xylene. These works created a number of challenges involving the management of significant health risks. The heavy contamination created potential for exposure of workers to hazardous substances to occur through inhalation, skin contact and ingestion. Consequently it was necessary for a high standard of personal protective equipment (PPE), respiratory protection equipment (RPE), decontamination facilities and a forced air extract ventilation system to be introduced and managed. The protective suits, boots, gloves and respirators required, along with heavy physical labour in a confined space under compressed air, resulted in significant potential heat stress problems which had to be managed.

Additional to these health protection difficulties was the engineering challenge of maintaining appropriate ventilation and other engineered control measures to limit VOC exposure within a hyperbaric environment. A detailed management system was implemented to control the exposure of workers to VOC contaminants and a work-rest schedule devised to control the risk of heat stress. Training, monitoring, supervision and maintenance were necessary to ensure that the primary control measures remained effective. Environmental monitoring data confirmed that adequate control of exposure to hazardous substances and heat stress was achieved despite work being undertaken in an unusually hostile environment.

The results of biological monitoring indicate that the performance of PPE and RPE were poorer than their designed specification. In conclusion it is therefore emphasised that even with the best of resources and organisation that PPE and RPE must only be chosen as a support control measure as part of a control system rather than the primary means of control.

• 1. INTRODUCTION

• 2. THE SCALE OF THE PROBLEMS

• 3. CONTROL MEASURES AND MANAGEMENT SYSTEM

• 4. THE EFECTIVENESS OF THE CONTROL SYSTEM

• 5. CONCLUSIONS

• Acknowledgements:

• REFERENCES