Summary and conclusions

Baggrundsrapport om miljøkrav til store olielagre

In the following paragraphs a resume of the contents of the report is given.

Chapter 1 describes the purpose of the background report and gives a short summary of relevant Danish legislation.

Chapter 2 provides a characterization of oil products in relation to their composition, their hazardous properties and physical-chemical properties relevant to an environmental risk assessment in case of leakage or spill. The chapter includes both fuel products and mixed products and additives.

Chapter 3 gives an overview over the principles of the construction and operation of oil storage facilities, including above ground tanks, buried tanks and earth covered tanks. The chapter describes tank structures, foundation methods, tank equipment, product pipe systems, tank farms, and discharge systems.

Chapter 4 describes the norms and technical regulations that apply to oil storage facilities, which can have relevance to environment and safety measures, that are required for environmental approval of oil storage facilities. For above ground storage the common European construction norm DS/EN 14015 is central for the construction of vertical cylindrical flat-bottomed steel tanks. Similar EU norms exist for smaller pre-fabricated above and underground horizontal cylindrical tanks. For larger buried tanks, the general construction norms apply. The regulations "Tekniske forskrifter for brandfarlige væsker" from Statens Brand-inspektion apply to all tanks.

Chapter 5 describes relevant EU legislation as well as regulations in selected countries with the objective of gaining insights in the status and developments in oil storage in those countries. The BREF document (Best Available Technologies Reference document) "Emissions from Storage" is a central advisory document for EU-countries and thereby Denmark with regards to the requirements on construction and operation of oil storage facilities. The BREF-document refers to the IPPC-directive as well as the Seveso II-directive and deals with the use of BAT for the reduction of emissions from storage facilities under normal conditions as well as releases due to unintended incidents and major accidents. Germany has more extensive requirements concerning environmental protection of oil storage facilities than other EU-countries and as an example requires the establishment of secondary collection on all existing and new tanks regardless of the type of oil product.

Chapter 6 deals with accidents leading to leakage, spill, and fire. It contains relevant literature studies of incidents and their causes and known incidents in Denmark are described. The literature studies identify lightning as a frequent cause of oil spills and fire. However, only approx. 20 incidents of tank fires are registered internationally per year. Therefore, it is assessed that many minor accidents involving spill with or without subsequent fires may occur, but without adequate documentation identifying the cause of the spill.

Chapter 7 gives a description of environmental risks including the probability and consequences of accidents involving leakage or spill of oil. Importance is given to the description of potential spreading above ground and away from the storage tanks as well as seepage into the soil and ground water under different geological and hydro-geological conditions, and hereby also in relation to the vulnerability of the environment.

Chapter 8 on the basis of the other chapters of the report recommendations are made on areas for standardization of environmental requirements for oil storage facilities. The recommendations are also based on the general experience of NIRAS and the project working committee, and include recommendations from trade associations and from the investigation board for the major Buncefield accident which took place in England in 2005. The safeguarding of the primary containment - steel tanks, product pipes, etc. - is to a great extent regulated by construction norms. Focus is therefore on the secondary collection system comprising membranes, tank bunds, etc. and on leakage control and alarm systems as well as discharge systems. A number of recommendations for constructive solutions are proposed for existing and new tank facilities with regard to the type of product stored and the vulnerability of the surrounding environment.

Chapter 9 describes recommended areas for self monitoring to the operator. Proposals are made for the execution of periodic routine inspections and detailed external and internal inspections. Furthermore, suggestions are made as to the degree of documentation required concerning the construction of the facility and for documentation of internal controls by the operator. For routine inspections carried out by the operational staff, a draft guideline concerning the scope and frequency of the inspection activities has been prepared. Detailed inspections are recommended to be carried out under the supervision of a certified tank inspector and should include the activities suggested by a recognized trade organisation. An advisory frequency for inspection is proposed which should be adjusted by the tank inspector based on documented knowledge of the developments in the conditions of the facility over time. The frequency should take into account an assessment of the residual life expectancy of the installation.

Chapter 10 gives estimated unit prices and cost estimates of environmental protection of a typical oil storage facility. The costs are strongly dependent on whether existing facilities are to be upgraded or new facilities are to be constructed.

Chapter 11 provides a proposal on the necessary level of information required in applications for environmental approvals. Besides the requirements in the "God-kendelsesbekendtgørelsen" (approval regulation), requirements for specific documentation of technical, operational, and management measures are suggested.