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Papers by Stephen Theophilus

Reliability Engineering & System Safety, Nov 2017

The oil and gas industry has been beset with several catastrophic accidents, most of which have b... more The oil and gas industry has been beset with several catastrophic accidents, most of which have been attributed to organisational and operational human factor errors. The current HFACS developed for the aviation industry, cannot be used to simultaneously analyse regulatory deficiencies and emerging violation issues, such as sabotage in the oil and gas industry. This paper presents an attempt to improve the existing HFACS investigation tool and proposes a novel HFACS named the Human Factors Analysis and Classification System for the Oil and Gas Industry (HFACS-OGI). Result found the HFACS-OGI system to be suitable for categorising accidents, following the analysis of 11 accident reports from the US Chemical Safety Board (US CSB). The HFACS-OGI system moreover revealed some significant relationships between the different categories. Furthermore, the results indicated that failures in national and international industry regulatory standards would automatically create the preconditions for accidents to occur.

International Journal of Environmental Science & Technology, 2010

Landfills’ Water Frontiers: Strategies for 2020 and beyond, Water Efficiency Conference (WATEFCON 2016), 7- 9 September 2016, Coventry, UK, 2016

Filter drains are usually laid along the margins of highways and highway runoffs are polluted wit... more Filter drains are usually laid along the margins of highways and highway runoffs are polluted with hydrocarbons and high levels of total dissolved solids. Hence, effective pollution removal mechanism is necessary in order to avoid contamination of surrounding soils and groundwater. Biodegradation is amongst pollution removal mechanism in filter drains, but is a relatively slow process which is dependent on wide range of factors including the type of pollutant and availability of nutrients. This paper reports on a study conducted to investigate the performance of slow-release fertilizer and struvite in enhancement of biodegradation of hydrocarbon in filter drains. French drain models incorporated with geotextile were challenged with cumulative oil loading of 17.8mg/m2/week with a view to comparing the efficiency of these two nutrient sources under high oil pollution loading and realistic rainfall conditions of 13mm/week. Nutrients and street dust were applied at one - off rate of 17g/m2 and 1.55g/rig respectively. The impact of the nutrients was studied by monitoring bacterial and fungal growth using Nutrient Agar, Rose Bengal Agar media and CO2 evolution. EC, pH, Heavy
metals, TPH, elemental analysis, SAR were used to investigate water quality of effluent of filter drains for potential application as irrigation fluid. The results show that nutrient application encouraged microbial activities and enhanced biodegradation rates with differences in type of nutrient applied. Furthermore, it was observed that incorporation of geotextiles in filter drains enhanced pollution retention and there is a potential opportunity for utilization of Struvite in SUDS systems as sustainable nutrient source.

Reliability Engineering & System Safety, Nov 2017

The oil and gas industry has been beset with several catastrophic accidents, most of which have b... more The oil and gas industry has been beset with several catastrophic accidents, most of which have been attributed to organisational and operational human factor errors. The current HFACS developed for the aviation industry, cannot be used to simultaneously analyse regulatory deficiencies and emerging violation issues, such as sabotage in the oil and gas industry. This paper presents an attempt to improve the existing HFACS investigation tool and proposes a novel HFACS named the Human Factors Analysis and Classification System for the Oil and Gas Industry (HFACS-OGI). Result found the HFACS-OGI system to be suitable for categorising accidents, following the analysis of 11 accident reports from the US Chemical Safety Board (US CSB). The HFACS-OGI system moreover revealed some significant relationships between the different categories. Furthermore, the results indicated that failures in national and international industry regulatory standards would automatically create the preconditions for accidents to occur.

International Journal of Environmental Science & Technology, 2010

Landfills’ Water Frontiers: Strategies for 2020 and beyond, Water Efficiency Conference (WATEFCON 2016), 7- 9 September 2016, Coventry, UK, 2016

Filter drains are usually laid along the margins of highways and highway runoffs are polluted wit... more Filter drains are usually laid along the margins of highways and highway runoffs are polluted with hydrocarbons and high levels of total dissolved solids. Hence, effective pollution removal mechanism is necessary in order to avoid contamination of surrounding soils and groundwater. Biodegradation is amongst pollution removal mechanism in filter drains, but is a relatively slow process which is dependent on wide range of factors including the type of pollutant and availability of nutrients. This paper reports on a study conducted to investigate the performance of slow-release fertilizer and struvite in enhancement of biodegradation of hydrocarbon in filter drains. French drain models incorporated with geotextile were challenged with cumulative oil loading of 17.8mg/m2/week with a view to comparing the efficiency of these two nutrient sources under high oil pollution loading and realistic rainfall conditions of 13mm/week. Nutrients and street dust were applied at one - off rate of 17g/m2 and 1.55g/rig respectively. The impact of the nutrients was studied by monitoring bacterial and fungal growth using Nutrient Agar, Rose Bengal Agar media and CO2 evolution. EC, pH, Heavy
metals, TPH, elemental analysis, SAR were used to investigate water quality of effluent of filter drains for potential application as irrigation fluid. The results show that nutrient application encouraged microbial activities and enhanced biodegradation rates with differences in type of nutrient applied. Furthermore, it was observed that incorporation of geotextiles in filter drains enhanced pollution retention and there is a potential opportunity for utilization of Struvite in SUDS systems as sustainable nutrient source.