About Hertfordshire Oil

 About Hertfordshire Oil Storage Limited (HOSI)

  • HOSI is a joint venture between Total (60%) and Chevron (40%), and forms part of the Buncefield complex in Hemel Hempstead, Hertfordshire.

  • Other companies at the Buncefield complex include BP, Shell and the British Pipeline Agency.

  • The Buncefield terminal is of key strategic importance to the UK as, prior to the explosion in December 2005, Buncefield handled 8% of overall UK oil supplies into the market, including 20% of supply to consumers in the South East. The terminal acted as a main pipeline transit point to meet 40% of Heathrow's demand for aviation fuel.

Site profile

  • Following the explosion on 11 December 2005, the site is closed and no longer operational. No product is currently moving through the terminal.

  • Prior to the incident, the terminal received, stored and distributed finished petroleum products through the Fina-Line pipeline which pumped the products from the TOTAL Lindsey Oil Refinery (TLOR) into HOSI. In addition, the terminal received fuels via the UKOil Pipelines or UKOP system.

  • Products stored on site included: Ultra Low Sulphur Diesel (ULSD), Unleaded Petrol, Super Unleaded Motor Spirit (SUMS), Kerosene, gas oil (for industrial and agricultural use) and aviation fuel.

  • 2.34 million metric tonnes of fuels passed through HOSI in 2004.

  • Approx. 400 road tankers were loaded each day on a 24-hour basis.

Site history

  • The complex began operations in 1968. The original companies on site were Fina (now Total), Texaco (now Chevron), Mobil (now BP) and Shell.

  • Since 1990, HOSI has operated as a joint venture between Fina (now Total) and Texaco (now Chevron).

Hertfordshire Oil Storage Terminal (HOSI) (Buncefield)

  • HOSI East, BPA and HOSI West are to the north of the site with BP and Chevron opposite and occupying the southern half.

  • The Buncefield complex has three cross-country supply pipelines. They include:

    • Fina-Line which feeds directly into HOSI West.

    • UKOP North and South feeding into and out of BPA (UKOP stands for UK Oil Pipelines).

  • There is a fourth pipeline, the West London Pipeline system which services Heathrow and Gatwick with aviation fuel.


  • HOSI West is the larger of the two sites, with 19 tanks which stored a variety of fuels excluding aviation fuel and kerosene, which was stored at HOSI East. All of these tanks were damaged beyond repair during the incident.

  • HOSI West consisted of an administration block, which contained administration offices, a laboratory and the control room from which the Supervisory Control and Data Acquisition (SCADA) system and other control systems, such as road loading, were operated.

  • The site also housed an engine test block which tested fuel quality, a loading rack with nine loading bays for road tankers, a receipt area for Fina-Line product coming in from the TOTAL Lindsey Oil Refinery (TLOR) and, at the far north of the site, a fire water lagoon.


  • HOSI East contained a total of seven tanks, three for aviation fuel, one Ultra Low Sulphur Diesel, and three for Kerosene.

  • HOSI East had a separate administration building which housed the road tanker transport companies, such as, Hoyer, Wincanton, and TOTAL Butler. This building has now been demolished.

  • In addition, there were also truck workshops adjacent to the administration block and a truck park that was able to accommodate approximately 80 vehicles. These workshops have now been demolished.


  • Hertfordshire Oil Storage Terminal (HOSI), Buncefield, Green Lane, Hemel Hempstead, Hertfordshire, HP2 7HZ.

  • The Buncefield depot occupies over 50 acres of which HOSI East and HOSI West take up 40%.

  • The HOSI site within the Buncefield complex divides into two parts: HOSI East and HOSI West, which are separated by BPA.

  • HOSI East, BPA and HOSI West are to the north of the site, with BP and Chevron opposite and occupying the southern half.

  • Transport access into the site is from Green Lane leading into the complex's private road which divides the BP/Chevron properties from HOSI East, HOSI West and BPA.

Surrounding Area

  • The Buncefield complex is approximately 7km (3 miles) from Hemel Hempstead town centre.

  • The north of the site is owned by BPA and held an aviation fuel storage tank with the remainder being mostly grassland.

  • North east of the complex are distribution warehouses.

  • East of the site is Crown Estate farmland.

  • The M1 runs to the east of the site approx. 1km (half a mile) away.


  • Environmental awareness formed an integral part of the induction process at HOSI.

  • The terminal conformed to the Environmental Protection Act 1990 Part 1: Authorisation of Process and the Petrol Vapour Recovery Regulations of 1996.

  • HOSI's Local Emergency Plan required full liaison with the Environment Agency.

  • HOSI East and West had a number of interceptors to prevent oil leakage into the sewage system, ground water and local watercourses.

  • All tanks were either stone or concrete bunded to reduce the risk of leaks spreading beyond the tanks. The tank bunds were built to contain 110% of the largest tank volume.

  • HOSI West had a vapour recovery unit where the vapour collected into the road tankers is pushed into carbon beds which filter and absorb the vapour and transform it into droplets which eventually condense into motor spirit. This resulted in the recovery of 6-7,000 litres of condensed motor spirit per day, which was both cost effective and environmentally friendly. This vapour recovery unit has now been demolished.

  • All supervisors undertook both waste disposal and local vapour recovery training.

  • BPA acted as a common user agency for the Buncefield complex and had overall responsibility for basic functions on the site including common drainage and road maintenance.