Lava-Cooling Operations During the 1973 Eruption of Eldfell Volcano,
Heimaey, Vestmannaeyjar, Iceland
U.S. Geological Survey Open-File Report 97-724

Pumping capacity increased

After lava had covered one fifth of the town by the end of March, there was a change in the operation. At that time 32 pumps, fully equipped, were received from the United States. Their capacity was 800-1000 l s^-1, the delivery head was approximately 100 meters in 1,000-m-long pipe sections. After they were put into use, the lava edge facing the town moved only a little, then came to a standstill.

All of these pumps arrived by airplanes at Keflavík on 26-30 March (on three U.S. Air Force C-141's and one C-5 transport aircraft), and they were transported by ship to Vestmannaeyjar immediately.

Originally it was planned to place all of the newly arrived pumping equipment on Nausthamarsbryggja [Nausthamars Wharf], where loading and unloading is rather easy in emergencies and access to seawater were good. But, when the lava flow started to cover the town, and headed directly towards the pier, it was decided, therefore, to move all of the pumping equipment to Básaskersbryggja [Básaskers Wharf] to cool the north side of the lava edge. A few pumps were also put on a barge from the State Lighthouse and Port Authority and on the dredging boat Vestmannaey; it pumped for awhile on the lava edge directly from the seaside.

When the pumps were installed, they were divided into four independent units in order to increase reliability. Each unit consisted of two low-pressure suction pumps that pumped into a reservoir vessel. Five to seven high-pressure pumps were used to transfer the water from the reservoir to a high-pressure tank. The water was transferred in 8 in - 12 in (20 cm - 30 cm) diameter pipes from the high-pressure tank onto the lava.

The pumps were assembled without any problems, and the work continued day and night. The first unit was put into use on 30 March, the second unit on 1 April, the third unit on 2 April, and the fourth unit on 4 April. The quantity of water these 4 units pumped was about 1,000 l s^-1, and it was aimed at the westerly lava edge from the processing plant up to Vilpa and across the lava flow above Sólhlíð. In addition, about 200 l s^-1 was pumped on the northern edge from Nausthamarsbryggja.

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Pumps and engines

Table 1 is a summary of the [types of] pumps used in the lava cooling from the beginning of April until cooling operations were terminated on 10 July 1973. It should be mentioned that the suction pumps were only used to supply the high-pressure pumps. It should also be noted that the quantity of water-pump discharge under a certain pressure does not indicate the actual quantity pumped each time, because it was dependent upon distance, delivery head, and pipe diameter.

The total number of pumps [deployed] was 43. Of those, 23, or more than half, were operated by gasoline engines, the others by diesel engines. The power of the gasoline engines was more than two-thirds of the total power of all the engines. They were considerably more inconvenient to use than the diesel engines, because of greater maintenance requirements and noise. The pumps that were connected to the gasoline engines were, in addition, designed to pump oil and gasoline, not water, and certainly not seawater. The pumps in question are the so-called "invasion pumps," that originally were supposed to pump oil-and-gasoline supplies ashore for the U.S. Navy. These pumps were manufactured before 1953 and had become obsolete. However, because of their great delivery head, it was possible to pump seawater far onto the lava and close to the crater.

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Table 1. - Summary of pumps [deployed for lava cooling] Number Capacity Quantity (1 s -1)    Capacity (m) Suction pumps 10 1,700 10-12 Suction/pressure pumps 7 575 30 Pressure pumps, single-stage 7 224 100 High-pressure pumps, double-stage 19 608 150 ___ Total 43 Horsepower total: 3,600 hp (2,700 kw) 23 gasoline engines: 68 percent of total power 20 diesel engines: 32 percent of total power

When the pumps had been operating for several weeks, the impeller shafts started to break (approximately 50 percent of them). The pumps were kept operating by constantly building new and improved shafts of stronger steel in Reykjavík.

The reasons for the shafts breaking were without a doubt manyfold; as was mentioned before, some of the pumps were not designed for pumping water, but for pumping oil and, therefore, the shafts were too weak. It was also noticed that the impellers eroded non-uniformly because of cavitation, especially on the suction pumps, and that caused the shafts to break from metal fatigue.

Other difficulties were caused because packing between the pumphousing and the shaft tended to deteriorate. The pumps then had to be taken out of service and the packing changed. Close to the end of the operation the valves began to wear out. However, this can be considered normal wear and tear, because, by then, the pumps had been operating almost continuously for three months.

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