The findings of the Competent Authority investigation in relation to the five themes identified earlier are given below.
The project to install the new 11kV feeder cable was a CDM Project and as such the requirements of the CDM Regulations should have been met in addition to the requirements of the Management of Health and Safety at Work Regulations. Due to the fact that electrical systems were involved the investigation also considered the requirements of the Electricity at Work Regulations.
A number of deficiencies were identified but due to the lack of positive, corroborative evidence linking identified persons to the actions which ultimately caused the cable failure no legal proceedings were initiated against any of the parties involved for failing in their legal duties. This was discussed with the Procurator Fiscal. The criminal law standard of evidence would have required evidence to prove beyond reasonable doubt who struck the cable and when and this was not available.
The HSE took enforcement action in this case by means of a formal letter to BP and the contractors involved.
Comparison of the organisational set-up with the "POPMAR" safety management system model in the HSE Booklet HSG65 "Successful Health and Safety Management" suggested major weaknesses in organising (in particular communication, control and competency), in planning and implementing and in monitoring. Underlying problems were identified in the following areas:
Specific examples include:
The number of failures and underlying causes demonstrated a failure in BP’s control of contractors and in the management of change in this incident.
BP failed to fully meet their own high performance expectations in "Getting HSE Right (GHSER)".
A previous power failure incident occurred on-site on 27th July 1999. A 33kV interconnector tripped due to a commissioning error leading to a site wide loss of electricity supply. This resulted in a loss of steam, plant shutdowns and significant flaring. On this occasion the plant emergency shutdown systems and the uninterruptible power supply (UPS) on the whole operated effectively preventing any further consequences.
By May 2000 at the time of the power distribution failure 17 out of 27 recommendations following the earlier incident had been completed, one had been superseded and one was not accepted. The remaining eight were scheduled to be completed by the end of 2000.
On a wider front a national study involving 100 chemical companies was previously carried out by the HSE during 1992/93 to identify the extent of the current awareness of power loss/surge issues at chemical companies and whether specific risk assessments had been carried out, back-up systems installed and maintenance issues identified. The study was carried out following a major power loss at a chemical complex on Humberside.
The previous study identified that although there was a general awareness, the perception of power loss/surge incidents amongst industry at that time was that they were mainly related to quality, production and profit issues rather than having safety implications. In addition at that time although there was considerable evidence that power loss/surge incidents were not uncommon there was no evidence of a major problem having occurred as a result.
Recent power loss incidents (including the incident at BP) have highlighted that power loss incidents may result in significant safety risks.
Certainly in view of the requirements of the COMAH legislation in relation to the control of major accident hazards it is important that other COMAH sites review power loss/surge issues for their own sites. (The COMAH Safety Report Assessment Manual SRAM Criterion 184.108.40.206 covers the issue of security of power supply.)
The following recommendations were made by the Competent Authority after the incident investigation into the power distribution failure.
BP should review the system for the planning and execution of future electrical supply work to ensure:
The findings of the HSE were consistent with those of the BP Task Force and were accepted by BP. A single complex wide power group was established immediately after the power distribution failure, with appropriate competencies and resource. This group forms part of the Power Station and Utilities Delivery Team which itself is part of the Forties Pipeline System and Infrastructure (FPSI) Availability Team. The power group has a clear remit to deliver fully available power systems across the whole Complex, in line with the FPSI overall goal to deliver 100% availability of site infrastructure systems.
BP should review standards and procedures for safe location of and digging around high voltage cables and standardise safe working procedure across the Complex.
The findings of the HSE were consistent with those of the BP Task Force and were accepted by BP. Work procedures and practices have been reviewed and revised to ensure appropriate assessments are in place prior to excavations relating to or in the vicinity of high voltage cables.
BP should adequately resource the maintenance of relays by manual testing every two years, and keep adequate records. BP should also review its written procedures for secondary injection testing to ensure a safe system of work is followed.
The findings of the HSE were consistent with those of the BP Task Force and were accepted by BP. Electrical inspection and test procedures have been reviewed and revised for use across the Complex. The Power Station and Utilities Team is responsible for the implementation of these procedures.