The November 2005 Buncefield Oil Storage Incident - Case Study Example

The November 2005 Buncefield oil storage incident Table of contents The November 2005 Buncefield oil storage incident 1 Table of contents 1 The November 2005 Buncefield oil storage incident 2 Introduction 2 Incident statistics 2 Cause of the incident 3 Mechanism of fuel-air explosion 4 Forensic analysis for source of ignition 4 Forensic analysis for explosion propagation 4 Effects of Buncefield incident to the environment 5 Incident land contamination 6 Reconstruction of the site 7 Site survey 7 Regulations on contaminated land 7 Contaminated land 7 Managing contaminated land 7 Developer’s responsibility on land reclamation of contaminated land 8 Duty of land care 8 Soil and geology studies 8 Soil Contamination risk analysis 9 Principle for land decontamination process 9 Removal of contaminated materials 9 Land decontamination compliances mechanisms 9 The desk based survey 10 Site description 10 Previous land use 11 Geology of the site 11 Recommended physical site investigation 11 Conclusion 11 Guidance policy following desk-based survey 12 Investigation of the depot site 12 Proposals for remediation 13 Compliance with regulations 13 References 17 Appendix 19 Figure 1: the fire pumphouse where ignition occurred 19 Figure 2: land contamination 20 Figure 3: direction of net drag impulse at Buncefield 20 Figure 4: developer’s action steps towards land decontamination 22 The November 2005 Buncefield oil storage incident Introduction Incident statistics The Buncefield oil cloud explosion incident occurred at 06:02:32 Hours on Sunday, eleventh, December 2005 through series of fuel-cloud explosions (Buncefield MIIB 2005:5-7). The incident occurred in a Buncefield oil storage and transfer depot in Hemel Hempstead. The incident caused minor injuries to 43 people but no incident related fatalities were reported. The incident resulted into evacuation of at least 2000 residents. The fire was brought down by effort of at least 1000 firefighters who consumed 750, 000 liters of foam concentrate and 55 million liters of water. The incident disrupted operations of 630 businesses and affected jobs of 16,500 employees (Buncefield MIIB 2005:22-30). Cause of the incident To-date, the cause of the incident has not been established. Oil specialists on BBC NEWS indicated the incident was caused by fuel-air explosion following failure of ‘leak detection system’ to detect fuel leakage resulting into built up of explosible fuel concentration in bunds and dense vapor-cloud formed due to frost conditions at ground level. While BBC NEWS 24 reported a security guard who had detected smell of fuel and requested an oil tanker driver to switch off the tanker engine that might have might have caused ignition of the fuel-air cloud. Mechanism of fuel-air explosion Fuel-air explosion, a type of BLEVE (Boiling Liquid Expanding Vapor Explosion) normally results when ignition of a gas-cloud occurs in a confined volume (Advisory Group report 2007:2). The flame propagation after ignition produce gaseous combustion products whose pressure buildup increases as heat of combustion increases leading into explosion when the confining structure fails (Advisory Group Report 2007:2). This explosion mechanism doesn’t provide guideline for the Buncefield oil incident whose greater percentage of explosion was not confined. Unconfirmed reports indicate the incident was a terrorist attack according to Italian television who described features on ‘July 2005 terrorist bombings’ citing a videotape that had been released by al-Qaeda who are alleged ‘had four days before the incident released threats on attack on fuel depots and refineries that contained oil ‘stolen’ from Muslim countries. Forensic analysis for source of ignition Flame modeling and numerical simulation proposed the ignition was initiated in the emergency pump house which conforms with witness statements and CCTV coverage as the emergency fire alarms were activated (MIIB Third progress report 2006 (figure 1) Forensic analysis for explosion propagation Forensic analysis indicated that the explosion was a function of hydrocarbon aerosol explosion (figure 3) that was characterized by stratified explosion as a subset of multiple ignition sources resulting into multiple detonations that was propagated by self-sustaining episodic explosion. The initial overpressures from numerical flame simulation and flame modeling using ethylene indicated that initial explosion generated overpressures of 1000 kPa with shock waves at 10-20ms. The mechanism of propagation was sustained by ignition of suspended debris and forward radiation from the flame front. Effects of Buncefield incident to the environment Following ignition of the fuel-air mixture, the explosion resulted into release of combustion products into the atmosphere that affected balance of atmospheric gaseous constitution thus creating imbalance of air quality. The incomplete combustion resulted into a smoke plume that was visible from far (Bower & Targa, 2006). Some of the gaseous products included Nitrogen IV oxide whose mass was 37.3 metric tones, Carbon monoxide 1712.7 metric tones, Benzene (Toluene, Xylene and Trimethylbenzene) at 58.3 metric tones, PM10 at 8249.5 metric tones, PM2.5 at 4949.7 metric tones, Dioxins at 1.32 metric tones while B[a]P at 284kg. The high heat energy from the exothermic process killed soil micro-organism. The heat energy resulted into ‘soil caking’ and calcification of soil hence negatively affecting the stability of the soil. The ‘shock waves’ following initial explosion which generated overpressures above 1000 kPa affected soil stability (Steel Construction institute, 2009). Incident land contamination Firefighting at Buncefield contributed to land contamination as a function of water and soil pollution (figure 2). The site suffered unknown quantities of contaminated surface and ground water fire. Forensic analysis on land contamination trial pits that were excavated at the depot site and its environs within a radius of 500 meters revealed the soil surface layers had been contaminated with fuel and fire fighting products (Buncefield MIIB, 2006b). The firefighting form contained PerFlouroOctane Sulphonates (PFOS), BTEX and MTBE (constituents of motor fuels) which have a long residual effect. PFOS are hazardous, non-biodegradable hence bioaccumulation in the environment and toxic. The PFOS are utilized as an additive that improves spreading properties of fire fighting form. PFOS, BTEX and MTBE are very stable and their half-life is not known. Research on PFOS has not yet established health hazards that arise after use, and sampling techniques for PFOS derivatives are not easier to implement due to lack of enough research on chemical properties of PFOS. Due to lack of enough data on minimum levels of PFOS, that ought to be in ground water or drinking water, the conclusion that PFOS was found to have little effect could not be conclusively made (Buncefield MIIB,2006a). The model that was used to carry out studies on movement of soil and water pollutants revealed the contaminants moved through chalk aquiver seams. The concentrations of the contaminants were high along River Colne that links River Thames (HSE, 2008b). The high concentration was due to discharge of 800, 000 liters of contaminated water that was released after three weeks of storage at the site. The decontamination process was not sufficient enough as the ‘process to render the water suitable to return to the environment was expensive.’ Although the oil companies had developed strategy for managing the fire water, the fire water was released before Environment Agency (EA) and House of Safety Executives (HSE) had provided its directive on ‘minimum impact of the fire water to the environment.’ Reconstruction of the site Site survey Regulations on contaminated land Change of land use following contamination is provided for by part IIA of Environment Protection Act (EPA) 1990 and Section 57 environment Act 1995 and qualified by associated statutory guidance (HSE, 2008b). Contaminated land A land qualifies as ‘contaminated’ if it exhibits ‘potential to cause harm to people, property or environment’ due to presence of chemical hazards in the soil or groundwater. Managing contaminated land Contaminated land (figure 2) can be brought back into use through ‘change of use’ either to residential or commercial. For commercial or residential purposes, the land should satisfy minimum requirements laid down by building regulation Act for dwelling structures and commercial buildings through increase of depth of foundation slab, placement of fencing around the contaminated site to seal it off, vapor extraction of the chemical contaminants, bio-pile remediation or phyto-extraction of harmful metallic elements by use of phyto-plants. Developer’s responsibility on land reclamation of contaminated land Duty of land care The duty of care of Buncefield site rests on Buncefield polluter who carries the burden for liabilities on Buncefield contamination namely the Hertfordshire Oil Storage Ltd (HOSL) owned by Total UK Ltd and Cheuron Ltd and British Pipeline Agency (BPA) Ltd owned by Shell and BP Oil Ltd. The polluters are responsible for ensuring regulators namely the Dacorum Borough council; House of Safety Executive (HSE) and Environment Agency receive updated information on strategies for reclaiming the contaminated land. The Dacorum Borough Council, as the planning authority should be involved in identifying and deciding necessary action on remediation of Buncefield site (AMW Contractors, 2009). Soil and geology studies The process of land reclamation should be advised by need to reduce chemicals pollutants from causing harm to the environment. Studies should determine if contaminants are concentrated on the surface or have filtered to water table. Soil studies should be conducted to determine soil water permeability, soil aeration, soil water retention capacity, leaching and calcification of the soil including soil cracking capability (Soil-Survey UK, 2009) Soil Contamination risk analysis Soil contamination risk analysis should be conducted to determine sites with high contamination and pollution. Following analytical results on soil levels of contamination, strategies for cleaning up the soil should be developed and detailed land remediation strategy outlined (BS BS8485, 2007) Principle for land decontamination process The process of water and soil decontamination should be conducted in natural settings with minimal disruption to soil and aquatic life. This ensures cost efficiency is attained (Figure 4) Removal of contaminated materials Site removal of contaminated materials should be adopted under severe land contamination. Though fast and cost effective, removal of contaminated materials to a landfill is not effective since the site requires resurfacing to replace removed materials making it non-cost effective. Land decontamination compliances mechanisms Three options exist as primary mechanisms for land decontamination processes. These are a. Desk-based survey which is characterized by identification of potential and probability of contamination b. Physical site investigation which is characterized by forensic, comparative and simulation models to identify land contamination processes with goal of identifying potential of harm from contamination process. c. Remediation step which includes all safety precautions and steps necessary to remove contaminants from the site as well as procedures and processes that should be employed to conduct decontamination. The desk based survey Desk-based survey assessment should be conducted to provide information that could be used to identify risks characteristic of the site that can bar development process. The analysis is vital for helping to design site-tailored recommendations that provide information on contamination status. Information derived from desk-based studies Site description This includes identification of the site, the current use of the site, site characteristics after contamination, adjacent sites portfolio and their current use. This is realized through site visit to identify evidence of contamination through analysis of samples that guide on level of contamination and procedures through which the contamination resulted. Previous land use A historical data on previous land use including the adjacent site backed by maps that ought to be attached to the report on previous utility of the site Geology of the site The land terrain and soil factors like soil acidity should be derived from the Environment agency, local authority and geological information and research work on the site. The geology of the site should also be provided with emphasis on hydrogeology and hydrology. Recommended physical site investigation In the event physical site investigation is required to advise on contamination status, desk-based survey should be utilized to develop modalities for designing appropriate site investigation criteria. Conclusion The report on desk-based survey should have appendices of site maps, relevant copies on site research with statutory authority approval, previous site investigation that has been conducted and any results and analysis that has been conducted before. Guidance policy following desk-based survey Following completion of desk-based survey, the report should be submitted to Dacorum Borough council, the planning authority who seek advice from Health and Safety Commission (HSC), Health and Safety Executive (HSE), Environment Agency (EA), Local Planning Authority and Hazardous Substance Authority (HSA) and Secretary of State for the Community and Local Government (CLG) and wait for reply in writing. There should be no development progress until communication from relevant statutory authorities is received (HSE, 2008b) Investigation of the depot site Depot site investigation should be conducted to identify presence and level of site contamination to determine measures that need be implemented to ‘return the contaminated land to suit proposed development. On identification of contamination level and severity, remedial measures should be identified which should comprise (figure 4): a. Desk-based survey b. Basis of site investigation, number of exploratory positions, sampling methods used and potential contaminant identification c. Risk assessment analysis and soil properties before and after incident d. Significance of identified contaminant based on Source-pathway-target linkage e. Potential to contaminate adjacent sites through quantitative risk assessment f. Remedial actions to ‘return site suitability for recommended use’ Proposals for remediation If contamination is a threat to proposed ‘change of land use’ there is need for remedial measures to stabilize the site. Remediation should be a product of desk-based survey, physical site investigation report and any necessary physical site investigations that could advise the remediation process. The remediation plan should outline the proposed remediation process, mechanism of addressing identified contaminant linkage and ongoing monitoring following completion of remediation. There should be a report on mechanism through which remediation realized set goals within remediation plan which should be supported by validation testing and any ongoing monitoring towards effecting remedial decontamination process. Compliance with regulations Currently, the Buncefield site is inoperable and any developer who intends to erect any commercial or residential structures should do so under consent of the Dacorum Borough Council (Buncefield MIIB, 2006a). The developer should satisfy pre-construction safety requirements through submission of a safety report to the House of Safety Executive (HSE) and The EA consideration. This is because, under the PHS regulations, the proposed site for development should have below threshold concentration of hazardous chemicals to human health and conform to standards of occupational health and safety. The developer should work in liaison with Hazard substances authority (HSA) and the Local planning Authority (LPA) in order to have hazard chemical risk assessment on soil and water (HSE, 2008). The developer should get approval and advice from the HSE on hazardous substance consent application as HSE conducts risks and hazards that could be exposed to human and specifies any conditions that the developer should amend, comply with and satisfy and advice minimum requirements that meet Hazardous Substances Authority guidelines (Buncefield MIIB, 2008a) s‘over and above compliance with statutory health and safety requirements.’ The developer should comply with development ‘consultation zones’ subject to advice of council on HSE proposal for new development (Buncefield MIIB, 2008b). The developer should ensure the type of building to be established conforms with building stratification thus the development should meet Council’s establishment of small-scale or community buildings and satisfy local education authority on construction of libraries, youth and childcare facilities like the case for the H18 site (Buncefield MIIB, 2006a). The developer should consult EA on local water supply so that it may conform to principle of ‘separation of existing structures from new development.’ The developer should thus define the type and scale of construction. The developer should comply with council’s proposed road network towards ‘reduction of traffic congestion’ through conforming to ‘strategies for minimizing construction impacts on road network’ by seeking advice from local highway authority. The developer should ensure proposed development meets Council’s building capacity for instance requirement for 50% units on H18 site or 30% on H14 site (Buncefield MIIB, 2008a). The developer should adhere to this requirement so that she may comply with requirement where ‘no development should add unacceptable burden on local facilities’ hence the developer should at his initial planning stage seek legal address on issues that concern his proposed type of development. The developer should ensure the development planning accounts for ‘cycle linkages’ to local shops and social facilities subject to standards of local plan for the developer’s identified ‘consultation zone and consultation distance’ (Buncefield MIIB, 2008b). The development should comply with local planning authority on ‘limitation of occupation.’ Key findings following Buncefield investigations Buncefield incident resulted from design failures of primary secondary and tertiary mechanisms of fuel containment (Steel construction institute, 2009). Primary design mechanisms for fuel containment are a function of tanks pipelines and vessels that ought to hold fuel and safety devices for safe operations. The secondary mechanism includes enclosed sections around fuel storage vessels termed as concrete bunds that should keep liquids or firewater while tertiary mechanism is component of drainage systems that minimize movement of fuel or firewater offsite subject to raised kerbs that limits liquids that breach the bunds (Advisory Group Report, 2006). Investigation established design failure of primary fuel containment was due to low integrity which ought to ensure no fuel escapes. The investigation established that safety designs should account for possible vapour cloud formation on fuel containment vessels and land use planning should advise the design process. The design should be able to manage escaping fuel cascading effect fragmentation and dispersion that resulted into formation of vapour cloud. The forensic analysis and numerical simulation established that design construction of fuel tanks and pipeline works shouldn’t create a favourable environment for formation of vapours. Numerical simulation using ethylene established that secondary and tertiary mechanisms are not important for environmental protection when rapid vapor cloud formation results. The flame propagation and explosion mechanisms established that cooling water from the fire pumphouse had made the firefighting non-effective hence design of cooling systems should account for firefighting efforts. The incident studies established that risk assessment should be an ongoing process and safety devices should be regularly tested for performance. References Advisory group report (2006) explosion mechanism: advisory group report retrieved 28th December 2009 from http://www.buncefieldinvestigation.gov.uk/reports/buncefieldagr.pdf AMW contractors (2009) contaminated land environmental services: retrieved 27th December 2009 from http://www.amwcontractors.com/contaminated_land_environmental_services.htm Bower, J. and Targa, J., (2006) Buncefield: National Monitoring, Envision and data activities Retrieved 23rd December 2009 from http://www.airquality.co.uk/reports/cat12/0606281406_05-AEA_national_networks.pdf page 3 Bower, J. and Targa, J., (2006) Buncefield: National Monitoring, Envision and data activities Retrieved 23rd December 2009 from http://www.airquality.co.uk/reports/cat12/0606281406_05-AEA_national_networks.pdf page 10 British Standard BS8485:2007 code of practice for the treatment of soil gas in brownsites Buncefield MIIB (2006a) the Buncefield investigation: third progress report retrieved 31st December 2009 from http://www.buncefieldinvestigation.gov.uk/reports/report3.pdf Buncefield MIIB (2006b) the Buncefield investigation report retrieved 29th December 2009 from http://www.buncefieldinvestigation.gov.uk/report.pdf Buncefield MIIB (2006c) The Buncefield incident 11 December 2005: The final report of the major incident investigation Board, page 39 Buncefield MIIB (2008a) illustrative model of a risk based land use planning system around petroleum storage sites: retrieved 29th December 2009 from http://www.buncefieldinvestigation.gov.uk/reports/dnvenergy.pdf Buncefield MIIB (2008b) Recommendations on land use planning and the control of societal risk around major hazard sites: retrieved 26th December 2009 from http://www.buncefieldinvestigation.gov.uk/reports/comahreport3.pdf Department of the environment, transport and regions and environment agency (2000) Model procedures for the management of contaminated land, contaminated land research report No. 11, London: DETR HSE (2008) major incident response and investigation and major incident policy and procedure review, retrieved 24th December 2009 from http://www.hse.gov.uk/enforce/mirai.pdf NSE (2006) HSE consultation report: retrieved 27th December 2009 from http://www.dacorum.gov.uk/pdf/HSE-consultation-report.pdf NSE (2008b) dacorum borough local plan 1991-2011 retrieved 26th December 2009 from http://www.dacorum.gov.uk/pdf/Development-Brief-report.pdf Promat (2007) environmental pollution firefighting strategies retrieved 24th December 2009 from http://www.promat-ap.com/pdf/pft19.pdf Soil-survey-UK (2009) Soil properties land contamination: retrieved 24th December 2009 from http://www.soil-survey.co.uk/img/cc_leaflet_small.pdf Steel construction institute (2009) Buncefield explosion mechanism, phase 1, volume 1 and 2; retrieved 24th December 2009 from http://www.hse.gov.uk/research/rrpdf/rr718.pdf Appendix Figure 1: the fire pumphouse where ignition occurred Source: Advisory group report (2006) explosion mechanism: advisory group report retrieved 28th December 2009 from http://www.buncefieldinvestigation.gov.uk/reports/buncefieldagr.pdf page 26 Figure 2: land contamination Source: Buncefield MIIB (2006) The Buncefield incident 11 December 2005: The final report of the major incident investigation Board, page 39 and NSE (2006) HSE consultation report: retrieved 27th December 2009 from http://www.dacorum.gov.uk/pdf/HSE-consultation-report.pdf Figure 3: direction of net drag impulse at Buncefield Source: Steel construction institute (2009) Buncefield explosion mechanism, phase 1, volume 1 and 2; retrieved 24th December 2009 from http://www.hse.gov.uk/research/rrpdf/rr718.pdf page 10 Figure 4: developer’s action steps towards land decontamination Read More