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2.1 Preventing contamination
With very few exceptions, all of the advice given here for preventing contamination of soil and ground water by MTBE, are the same as have been applicable for traditional gasoline for tens of years.
2.1.1 Importance of prevention
Gasoline - with or without MTBE - should not be allowed to contaminate soil or groundwater. In most countries, strict regulations exist to prevent gasoline leaks and spills, unfortunately these are not always properly enforced. Oil companies, their distributors and retail site operators have comprehensive procedures in place for the safe storage and handling of gasoline.
No component of gasoline, including MTBE, is capable of seeping through properly designed, constructed, tested and maintained systems. A responsible attitude and good operating practices will prevent leaks and spills, and the resulting contamination of soil and groundwater. Nevertheless, human error or equipment failure may lead to an accidental release. In such cases, immediate steps must be taken to deal with the situation. Delays or attempts to cover up the incident can lead to more serious pollution, greatly increased clean-up costs and significant legal penalties.
2.1.2 Storage and handling of gasoline
2.1.2.1 Key checkpoints
Environmental protection at retail sites should focus on a simple common sense principle: prevent leaks and spills - but if an incident does happen, clean up the mess immediately.
To put the principle effectively into practice, procedures, systems and technical installations need to be focused on:
leak/spill prevention, detection and containment
emergency response
site investigations and risk assessments
remediation as needed
Tools in this work are:
proper design and installation of equipment, facilities and structures
regular inspection of facilities and equipment
adequate maintenance and control
site personnel guidance, training and supervision
Some key technical/operational considerations are:
pavement and its material
oil separators, yard drainage, sewer systems
overfill prevention systems
spill catch basins for filling connections
drip pans under pumps
liners and soil venting tubing under forecourt, tank pits and filling areas
piezometers and monitoring programmes
electronic leak detection devices (electronic level control, VOC-detectors in the tank pit and under the filling areas)
proper operating procedures, including maintenance
operating personnel guidance, training and supervision
These technologies need not be generally applied, but must be considered case by case, depending on site hydrogeology and other relevant aspects.
As in any other case, the effectiveness of technological and operational procedures will depend on the level of actual compliance. Therefore, some sort of inspection or (internal) auditing procedure will increase the effect of such procedures.
The positive effects of improving both the level of enforcement (leading to increased compliance) and the level of technical integrity (leading to a reduction in leaks) are clearly described in a presentation and accompanying paper "MTBE / UST's: A True Perspective". This paper was presented at an environmental law conference in California (November 2002). The presentation can be downloaded from http://www.calgasoline.com/MEA_000E.PDF and the accompanying text from http://www.calgasoline.com/MEA_000F.PDF
One outcome of the EU Risk Assessment on MTBE refers to tank bottom waters: the water phase incidentally accumulated at the bottom of MTBE storage tanks. Proper treatment of this water phase is an essential component in reducing water pollution.
A different issue in the USA concerns MTBE found in water in small concentrations, especially in certain recreational lakes, some of which also serve as water reservoirs. In those cases, the problem is not caused by leaking storage tanks, but by recreational boats’ 2-stroke gasoline-driven outboard motors, which blow exhaust gases directly into the water. Combustion in such motors is less than complete, therefore a relatively large proportion of unburned fuel - including MTBE - ends up in the water
2.1.2.2 Detailed best practice guidelines
In most countries, oil industry associations, together with the relevant authorities, have produced comprehensive instructions and recommendations on proper technical installations and operational procedures.
The Institute of Petroleum documents listed below were prepared by the industry, including representatives from the multinational oil companies and the authorities, and were produced for the UK. However, the technical and operating principles and practices described are generally applicable.
A brief summary and Chapter 2 (Risk Assessment) of: "Guidance for the Design, Construction, Modification and Maintenance of Petrol Filling Stations", November 1999, a document published by The Association for Petroleum and Explosives Administration (APEA) and The Institute of Petroleum (IP), United Kingdom can be found in appendix no. 7.pdf
The following (appendix no. 8.pdf) is an American approach to the same topic. It is The California MTBE Research Partnership's report " Survey of Current UST Management and Operation Practices" and contains a lot of valuable information on the topic.
Another IP document, "Environmental Guidelines for Petroleum Distribution Installations", May 1996, describes the proper installations specifically from the environmental protection point of view. The contents list and summary is available in appendix no. 9.pdf.
In 2001, Arthur D. Little prepared a report for the European Commission assessing whether groundwater within the European Union (EU) faces a similar potential for widespread contamination by MTBE as has already occurred in the USA, and whether this risk is mitigated by controls or obligations present in Member States that may or may not exist in the USA. The report, which can be downloaded from http://www.environmental-expert.com/articles/article1001/article1001.htm, concludes:
“Widespread MTBE contamination on the same scale as in the USA (especially California) is unlikely. The risk of groundwater contamination is unlikely to increase, given important differences between the USA and the EU, although robust enforcement of the existing Member State regulatory framework is required to ensure this risk remains low in the future.”
2.1.3 Storage and handling of neat MTBE
2.1.3.1 Basic guidelines
The water solubility of neat MTBE, its effect on some elastomeric polymers, and fire fighting foam requirements are different from those for gasoline. Except for these differences, design and operation standards applicable to gasoline storage and handling facilities also apply to MTBE.
Generally, all technical requirements and operational practices which apply for gasoline are applicable for neat ether oxygenates and also gasolines containing ether oxygenates, with the following exceptions:
gasket materials compatibility to be checked
vapour recovery design, capacity to be checked
storage tanks should have floating roofs and domes
tank bottom water phases to be directed to waste water treatment
special emphasis on leak prevention/detection and soil/groundwater protection
emergency response: oxygenates-compatible extinction foams, adsorbents
minimised response time for soil/groundwater remediation in case of a leakage or splash
medical emergency response
With respect to spills or leaks, owners and operators of installations that handle gasoline should be well aware of local, regional and national regulations and legislation. As a minimum, EFOA recommends to alert local water authorities in any major gasoline spill or leakage whether there is MTBE or other ether oxygenates involved or not. The same applies even for small spills and leakages in sensitive areas.
Neat MTBE is a chemically stable, highly flammable, and highly volatile liquid. Although it is relatively non-toxic to humans, it behaves as an anaesthetic when very high vapour concentrations are inhaled. It does not polymerise, nor will it decompose under normal conditions of temperature and pressure. Unlike most ethers, MTBE does not tend to form peroxides (auto-oxidise) during storage.
MTBE is non-reactive. It does not react with air, water, or common materials of construction. The reactivity of MTBE with oxidising materials is probably low, however, without definitive information, it should be assumed that MTBE reacts with strong oxidisers, including peroxides.
MTBE may hydrolyse in the presence of some acids. MTBE is very stable in the presence of reducing agents and reactive monomers.
Bulk quantities of neat MTBE should be received, stored, processed, and disposed of only in facilities designed for those purposes. Storage systems should be inspected for elastomer compatibility before introducing MTBE for the first time. After initial inspection, storage systems should be operated as outlined in the product safety bulletin. Appropriate emergency notification and response systems for fire and spill management should be in place at each facility where MTBE is received, stored, or used. MTBE should be handled only by workers trained in safe handling methods and response to emergencies such as spills or fires.
For more information regarding safe handling and storage, please see the MTBE Product Safety Bulletin
2.1.3.2 MTBE Product Safety Bulletin
An MTBE Product Safety Bulletin is provided under appendix no. 10.pdf.
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