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10857 Chemical accident in France with benzine (gasoline) unleaded
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General accident information
Class/Quality * * * * *
Year 1990
Summary Derailment of 9 tankwagons carrying unleaded fuel
Caused major fire and explosions, release of fuel
At tiny village and pollution of soil and wells of
Drinking water
Country F
Activity RAILTRANSPORT
Location RAILWAY
Chemicals Benzine (gasoline) unleaded
Cause Technical-failure
Fatalities/Injuries 0 / 0
Occurrences or events Burst/Rupture, Clean-up, Derailment, Drive,
Evacuation, Explosion, Fire, Fire fighting/Emergency response,
Fire fighting/Emergency response, Fire fighting/Emergency response, Get-loose/Lose, Ignition,
Natural event, Overturn/Capsize, Pollution/Contamination, Recover,
Release, Slow-damage, Traffic-interruption, Vaporize
 
 
Full accident information 
download accident report Click here to view a document containing the full accident information

Country: FRANCE (F)
Date : 1990 1203


At 2353 hours a convoy of railroad tanker cars carrying nearly 2E+6/kg of hydrocarbon fuel derailed without any apparent reason on crossing a small community. Out of the 22 tankwagons, 9 were damaged, caught fire and led to the fire spreading to nearby buildings. The members of the public, surprised in their sleep, were obliged to hurry from their homes. The local fire brigade reached the site 5/minutes later. Four explosions took place in the next 30/minutes and the smoke produced by the fire spread over4 a wide area with each successive explosion. By this time, 2 two-storey houses, a garage and a car showroom were totally involved. On the other side of the RN, the facades of buildings were already beginning to burn. A considerable firefighting force set up gradually as emergency reinforcements arrived, coming from nearby emergency centers. The foam unit from L. arrived at 0220 hours. Two hours later, extinguishing operations proper began by fighting the fire with foam and quickly bringing it under control. In total 180 firemen of 3 different counties managed to control the fire at 0630 hours next morning. Specialized companies handled the operations of transfer and degassing of the rail cars and the railroads were to be cleared over a period of several days using cranes.
An area of 1/km long and 400/m wide, including 8 houses, 2 garages and 30 cars were destroyed, 8 houses were damaged and 22 residents have to move to another house.
250-300/m3 of fuel seeped into the soil and polluted an area of 2/ha of land. The monitoring and processing of underground soil and water pollution were also handled by a specialized company. Up to 2/meters of free product gasoline was encountered.
The consumption of fruits and vegetables were forbidden in an area of 12.5/ha.
At about 1600 hours it was agreed that the RN could be re-opened to traffic. The rail traffic was halted for a week.
Two days later, specialists started drilling in different locations to evaluate the extent of pollution.
Several months after the accident, measurements were made in the sub-soil of nearby dwellings so that the necessary safety measures could be taken.
A year after the accident water supplies were threatened. There was a danger the spilt fuel will permeate further into underground wells which supply drinking water.
Vapour stream processing was via catalytic oxidation, consisting of two 2,000 SCFM and one 1,500 SCFM units. To date all free product has been recovered.
The community undertook the refurbishing of the accident zone by means of landscaping.

Cause
An administrative enquiry report suggested that the accident may have occurred due to the passage of the train at an excessively high speed on a distorted railway track. The defect appeared due to the weakening of the railway tract seating following torrential rains.
The passage speed (93 km/h) was normal for a railway track without any defect. However, if this defect was known, the driver would have undoubtedly reduced the train???s speed.

Actions taken
According to the assessments made following the accident, 80-90% of the spilt hydrocarbons were in gaseous or
liquid state on the land surface above the water table (???unsaturated??? zone). 10-20% of the hydrocarbons were
consumed by the fire or evaporated into the atmosphere. Petrol was found on the slope supporting the railway track and on the surface of the water table in a thin clay structure on the foot of a hill.
For safety reasons, several administrative decisions to demolish effected residences were promptly taken.
Lastly, once the hydrocarbons were extracted from the wells and caves, the polluted land was treated in three stages:
1.
Drawdown to avoid the pollution from spreading into the water table. The 1st pumping operation at a rate of 4 m3/h was carried out on 16/12/90 followed by tow others. On 10/01/91, the total drawdown rate was 16 m3/h.
2.
Reduction of the polluted area by precisely characterising the composition of the bottom soil and contamination. Forty surveys were carried out by an organisation specifically appointed for this purpose.
3.
Site cleaning in three successive stages:
a. Pumping or removing the surface slick.
A first drilling operation was carried out in January 1991 to the east of the railway tract. From December 90 to April 92, 30-40/m3 of hydrocarbons were recovered from the grounds. The drawdown water whose hydrocarbon concentration was less than 20/ppm was released into the nearby river.
b. Bioleaching tests.
Two pilot plots of 350 and 760/m2 were tested. The treatment proved to be effective only for a depth of 2/m. The tests were stopped.
c.
Vacuum extraction.
Venting operations were performed on polluted lands. The positive results obtained led to the selection of this type of treatment. A call for tender stating the quantitative objectives to be reached within a stipulated time frame was floated (hydrocarbon concentration in soil less than or equal to 10/ppm, no slick after one year of cleaning operations).
All drilling sites were operational on 23/07/92. Three mobile gas treatment units by incineration were set up.
Land cleaning operations ended mid-February 93. Vacuum extraction helped recover 146/m3 of hydrocarbons in 45
weeks. To this volume can be added
- 50/m3 of slick removed since December 1990,
- 10 m3 obtained during initial venting,
- 4-5/m3 of hydrocarbons neutralised using bioleaching.
The total volume of extracted hydrocarbons amounted to about 210/m3.
The cleaned lands were not returned to their owners but recovered by the town authorities and used for town development.

Lessons learned
Emergency and rescue operations for the public, questions on preventing the pollution from spreading, soil and slick treatment had to be quickly studied. The authorities present (town authorities, rail transport company and administration) were required to take urgent decision on assessing the extent of pollution and its actual and potential effects. Moreover, decisions to implement preventive measures aimed at stopping the hydrocarbons from spreading had to be taken even though responsibilities were not clearly defined and no assessment on the time required and cost involved was available.
Over and above these aspects, the accident is a learning experience in managing polluted sites.
On a technical level, the vacuum extraction process proved to be efficient and was used few months later, a few kilometers south in another railway accident took place.
The unsuccessful bioleaching tests show that site clean up techniques not only depend on the nature of the pollutant(s) but also on the specificity of the effected site (nature of soils, permeability, depth of water table, flow rate, etc.) and an indepth study of the above parameters.
This accident also illustrates the positive role played by the municipality in ensuring the smooth running of site clean up operations and its wise decision to purchase the cleaned land. This facilitates the setting of formal restrictions on soil and subsoil usage in urban development documents ensuring compatible use of the land with the prevailing residual pollution.
With regard to feedback that can be applied to classified installations, it is important to note that the seriousness of the potential consequences of such an accident calls for the urgent implementation of resources to prevent the slick from spreading followed by prompt assessment and clean up of the pollution.
The uncontrolled large scale spreading of volatile inflammable liquids poses a serious threat to people, property and the environment especially if the pollutants reach networks generating an explosive atmosphere in a confined medium.
These situations need to be taken into account in safety studies and rescue plans.


Un train compos?? de 22 wagons d??raille: 12 wagons se retournent, 9 wagons-citernes de carburant prennent feu et explosent. L'essence enflamm??e incendie des habitations proches et se r??pand dans les ??gouts. Dans la zone sinistr??e qui s'??tend sur 1 km de long et 400 m de large, 8 habitations, 2 garages et 30 voitures sont d??truits, 5 maisons sont endommag??es ; 22 personnes ??vacu??es sont ?? reloger. Les 180 pompiers r??ussissent ?? ma??triser l'incendie ?? 6h30. 250 ?? 300 m3 d'essence s'infiltrent dans le sol et polluent une surface de 2 ha de terrain. Les puits agricoles voisins sont ferm??s et les pompages d'eau limit??s. La consommation de fruits et l??gumes est interdite dans un p??rim??tre de 12,5 ha. La circulation ferroviaire est arr??t??e durant une semaine.



 
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