The Malpasset Dam Disaster - could the Var suffer again?

« De tous les ouvrages construits par la main humaine, les barrages sont les plus meurtriers. » (“Of all the works of mankind, dams are the most murderous”)

These were the words expressed in 1952 by André Coyne, the engineer appointed to construct the dam at Malpasset. How right he was!

The disaster which occurred here on December 2, 1959 – i.e. almost 50 years ago – was the worst catastrophe ever to occur in France during the last half century. A few months following the disaster I visited Fréjus and witnessed myself the havoc which it caused.

Above all there is the question whether such a disaster could ever occur again either in our region or elsewhere. In this respect it should be noted that many dams also in our region are significantly older than this dam at Malpasset.

Following the end of the 1939 – 1945 war the French government embarked on an ambitious infrastructure programme (aménagement du territoire) including dams to be used primarily for the generation of electricity. The purpose of the dam at Malpasset, however, was not primarily the generation of electricity, even though it did have this capability. The region around Fréjus had always suffered from a lack of water. The Romans solved this problem partially through the construction of a 41.6 Km aqueduct, the remains of which can still be seen in several places. The primary purpose of this new dam was thus for irrigation. The secondary purpose was to control the waters of the river Reyran, which has its source near Bagnols. Dry for about 9 months of the year it often becomes a raging torrent in the winter, which regularly caused substantial flood damage. Since the disaster this danger has been at least in part diminished by the construction of a concrete bed for the river.

The site selected for this dam was at Malpasset. A track used to pass by this spot and stage coaches were regularly held up here by a band of highwaymen. This place was thus named Malpasset – “c’est mal passé”. The Malpasset dam was of the arch – or voûte – type and the retention lake behind it 4 km long. The capacity of the retention lake was 50 million cubic meters or 50 million tons. The dam itself was 222 metres in width, 66 metres high and had a thickness of 6.78 metres at the base and 1.50 metres at the rim. This made Malpasset the thinnest arch dam in the whole world! For comparison, the dam of Sainte Croix on the Verdun, which is the third largest dam in France with a reservoir of 751 million cubic metres, i.e. fifteen times greater than Malpasset, has a thickness of 7.50 metres at the base and 3.00 metres at the rim. Since arch dams become more resistant as the pressure of the water increases, the material costs are significantly lower that those of gravity – or poids – dams.

Construction started in 1952 and the dam was put into operation in 1954. However, 5 years later it was only half full. On the one hand the level of rainfall between 1954 and the autumn of 1959 was unusually low. On the other hand the owner of some of the land to be expropriated took the matter to court and it was not until the middle of 1959 that this matter was settled.

In November 1959 South Eastern France was suddenly subjected to diluvian rainfalls. The level of the Malpasset reservoir started to rise at such a fast pace that the engineers did not have the time to make the tests necessary during the first filling of the dam. These include not only tests on the resistance capability of the dam itself but also checks on the strength and resistance of the foundations. On December 2, 1959 the rains became literally torrential and by 12 noon the level of the reservoir had reached its maximum level. The guardian, André Ferro, asked for permission to release the excess water, but the answer was no. On that day the concrete had just been poured for the pillars of the bridge which was to carry the A8 over the Reyran. The release of any water might have damaged this new bridge. (Incidentally, the A8 from Fréjus to Cannes was the first ever portion of toll autoroute constructed in France). At 18.00 hours permission was eventually given to release some water, but, so hard was the rain, that it took almost three hours to lower the level by just a few centimetres.

At 20.50 hours André Ferro returned to his home which was situated 2 Km below the dam for a very quick dinner and, still worrying about the situation, prepared to return to the dam. As he left his house at 21.13 hours, he heard a sort of growling and rumbling as well as the wrenching of metal. He shouted to his wife, “the dam, quickly, everything has collapsed!” Picking up his young son he and his wife fled up the hillside and fortunately survived.

At 21.13 hours therefore the Malpasset dam literally exploded, releasing 50 million tons of water which constituted initially a wave with a height of 50 meters travelling at a speed of 70 kph and carrying with it enormous chunks of concrete down the valley, some of them weighing up to 600 tons. Some of these remains can be seen even on the other side of the autoroute, more than one kilometre distant from their original location. Within a few minutes 53 houses were destroyed in the valley of the Reyran alone and already 120 people had been killed. Seven minutes after the rupture of the dam millions of cubic metres of water and mud reached the western part of the city of Fréjus. At 21.40, i.e. 27 minutes after the collapse of the dam the wave, now only 2 metres in height, finally passed into the sea, taking with it finally 6 planes from the naval airport.

The human toll amounted to 423 dead, namely 135 children under 15 years of age, 15 minors between 15 and 21 years, 134 men, 112 women and 27 unidentified persons. The disaster also orphaned 79 children.

3.200 hectares of land were ravaged. 700 hectares were irrecoverable, since all the topsoil had been washed away and 900 hectares had to be completely restored. 30 farms were completely destroyed and 50 were partially destroyed. 60 agricultural buildings were completely destroyed and 45 partially destroyed. Nearly all agricultural implements were lost. Livestock was also lost: 15 horses, 1000 sheep and all poultry. It was also reported – and I believe this adequately illustrates the priorities of the inhabitants – 80.000 hectolitres of wine were also destroyed.

Furthermore, 2.5 kilometres of the railway track was washed away, thereby cutting the eastern Var and the Alpes-Maritimes off from the rest of the French railway system. The Geneva – Riviera express missed being hit only by ten seconds.

In the town itself 155 buildings were completely destroyed and 796 were damaged.

Immediately the Plan ORSEC (meaning organisation des secours) was launched. A squadron of US helicopters based in the region also took part in the rescue operation.

The enquiry into the reasons for the collapse of the Malpasset dam lasted for 8 years. Four possible reasons were put forward for this:

An earthquake
The explosives used for the construction of the autoroute
The design of the dam itself, in particular the thinness of the construction
The foundations

The first three potential reasons were quickly discarded. There had been no earthquake. The work on the autoroute was taking place at a distance of 400 to 500 hundred metres on the other side of the hill. And there were no indications whatsoever regarding the design and the construction of the dam itself.

There were, however, indications that the foundations of the dam at its south-eastern end were flawed. Indeed, shortly before the disaster witnesses had seen large quantities of water passing through the rocks in this location. Additional analyses determined that the dam had at this end been built on a non-homogeneous rock formation which had several underground faults. As one can see today, on the south-eastern end of the dam there are virtually no remains existing. As was said at the enquiry, “the foundations popped like a cork and the dam literally opened up. At the north-western end, on the other hand, a small portion of the superstructure remains.

The enquiry then concentrated on the question of whether or not any blame could be attributed to the engineers responsible for failing to determine the actual state of the rock formation prior to the construction of the dam.

The court finally decided in 1967 that no blame could be allocated and that the disaster was a fatality.

This was the only time that an arch dam ever collapsed. Malpasset has in the meantime become a major reference for the construction of dams throughout the world.

Malpasset was not the only case of a disaster involving a dam.

If one analyses the 40 greatest disasters in recent times, one will determine that only three are attributable to mankind rather than to nature. The most important of these occurred on August 11, 1979, when the Machhu-2 dam in Gujarat state in India collapsed, wiping out the industrial town of Morvi. The human death toll was estimated at about 15,000 people. Machhu-2 was an earth dam which collapsed as a result of extremely heavy rainfalls. The spillway capacity of this dam was 5,663 m3 / second, whereas the volume required to be evacuated after the heavy rainfall was estimated at over 16,000 m3 / second.

Closer to home, at 22h39 on October 9, 1963 there was a major disaster at the Vajont dam, situated in the Friul in the Province of Porderone. The Vajont dam had been constructed during the years 1956 to 1959 and the water retained by it was three times greater than that of Malpasset, namely 150 million cubic metres. As a result of a landslide 260 million m3 of earth and rocks fell into the dam, causing a 150 metre high wave consisting of almost half the water in the reservoir to spill over the dam. 1910 people died as a result of this disaster, of which 1909 were killed and one engineer responsible for the disaster committed suicide. In fact, there was from the very beginning of the construction a major risk of a landslide (a minor one actually took place on November 4, 1960) but this possibility had been covered up by the engineers. The chief engineer was eventually sentenced to 5 years imprisonment in 1977, but was pardoned one year later.

Significantly, this arch dam survived the disaster intact, although for obvious reasons it is no longer in operation. It was, incidentally, also much thicker than that of Malpasset, measuring 22.11 metres at the base and 3.40 metres at the rim.

On the basis of these catastrophes we should also consider the risk of such disasters re-occurring and whether our early-warning systems are adequate.

Dams are used primarily for the generation of electricity – as well as for irrigation. There are today over 40,000 dams in operation in the world, generating a total of about 1000 Gigawatts of electricity. This represents more than the total of Germany, France and the United Kingdom together produce from all sources, 50 times more than is generated by, for example, Egypt (with a population of 80 million) and 350 times more than is generated by Ethiopia (with a population of 77 million).

Norway, for example, generates all its electricity from hydro power plants. So does Paraguay, which also exports a similar amount to neighbouring countries. France produces 15% of its requirements from hydro power, versus 79% from nuclear power plants and 6% from fossil fuels and it is expected that this portion generated from fossil fuels will shortly be replaced by wind power.

Since 1800, 150 dams have collapsed. Apart from Malpasset, one other also burst in France in April 1885, namely Bouzet in the Vosges, leading to the deaths of 87 persons.

In France an organisation known as the DRIRE is responsible for the constant surveillance of all dams. It specifies the following types of risks:

Technical: faults related to the dam itself or the foundations, particularly at times of high water levels (e.g. Malpasset)
Natural: earthquakes, landslides (e.g. Vajont) and exceptional high water levels (e.g. Machhu-2)
Human: insufficient control and supervision, terrorism, war (e.g. Möhnesee, Edertalsperre). These attacks in Germany caused approximately 2000 deaths, nearly all of which were those of prisoners of war.

In our own region the two most likely risks are those of earthquakes and landslides. There have been major earthquakes in our region every century for at least one thousand years – with the exception of the 20th century. The next earthquake can therefore now be considered as overdue. For example the last great earthquake occurred on February 23, 1887 causing 643 victims, mainly on the Italian Riviera but also 8 in the Alpes-Maritimes. Obviously, a major earthquake could destabilise either the dams themselves or their foundations.

Landslides are also another danger, particularly following heavy rainfalls. There is apparently also the risk of a landslide at the barrage de Ste Croix. They could also be triggered by a major earthquake. Anyone who has, for example, visited the Friul valley since the major earthquake of 1976 will have seen the enormous land and rockslides triggered by this disaster.

An early warning system has been put into place by France as well as by all other European countries concerned. 4 phases have been specified:

Increased surveillance
Serious preoccupation
Immediate danger
Collapse of dam

In the phases 3 and 4 the prefectures concerned are informed immediately by a direct telephone line and the population by a combination of sirens and automatic telephone calls.

On a final note, the largest dam in the world, the Three Gorges Dam on the Yangtse River with an electrical generation capacity of about 20 Gigawatts, which is equivalent to that of Egypt or Pakistan alone, has suffered dozens of landslides during its filling up process. Furthermore, it is exposed to potentially severe seismic activity. Should this dam ever be breached, a total of 4 million people living beneath the dam could be affected!