Chaiten 2008


TRANSPORTATION

The road networks in the surrounding regions of Chaitén were adversely impacted by ashfall (Wilson et al., 2012b). It is reported that Chubut province of Argentina, 90 km SE of the eruption source experienced thick heavy fine-grained ashfall, resulting in reduced visibility making road travel unsafe. Ash mixing with water created a slippery surface on the roads in some areas, reducing traction and causing several accidents. Reports did state that compacted ash was easier to drive on when wetted, thereby preventing remobilization (Wilson, unpublished data).

The rail network also experienced issues, predominantly around ensuring trains maintained traction. This was mainly to do with ash mixing with snow to from a slurry mixture (Wilson, unpublished data).

Several aircraft sustained significant engine damage from ash clouds. Airports in Chile, Argentina and even as far as Uruguay, up to 2,300 km away were impacted resulting in closure or cancellation of flights (Ball, n.d.).

Marine transportation was largely used for evacuations from Chaitén. Both large and small vessels experienced issues with floating pumice and ash clogging engines and damaging engine components (Wilson et al., 2012b).

POWER NETWORK

The hydroelectric dam at Futaleufu suffered damaged as a result of ashfall (Wilson et al., 2012b). Ashfall blocked rain gauges in the dam's catchment. As it was rainy season, dam levels could rise rapidly. Strict protocols were put in place to reduce ash contamination into machinery. A permanent team was housed there for a month instead of the standard shift changes as roads were slippery and to prevent ash remobilization from traffic. During dam clean up efforts, over 180-tonne of ash was removed from the powerhouse roof and substation area. Along with reduced output, electrical distribution was also impacted at the dam site. Vertical insulators at the step-over substation suffered ash accumulated induced flashovers. Power lines to Futaleufu were also impacted. On a 68 km (42 mi) length of line, 10-20% of insulators flashed over upon receiving 50-100 mm (2-4 in) of ashfall. These events occurred several days after the initial ashfall during a period of light rain. A subsequent period of heavy rain-washed the majority of this ash off, but fine-grained ash remained stuck to the underside of the insulators. Local authorities decided to replace all insulators as it was deemed too laborious to assess each one.

In contrast, the Chubut hydroelectric dam, located 90 km SE from the volcano experienced no decrease in electrical output (Wilson et al., 2012a). The dam site received 50-100 mm (2-4 in) of ash coverage, but the catchment lake received much more. Due to the fine grained and pumice content of the ash, it remained suspended in the lake water. This dam remained operational during eruptive events, but abrasion and corrosion was an issue to dam machinery.

There were no reported outages on local supply lines around the townships receiving ashfall although controlled outages occurred for transformer cleaning.

COMMUNICATIONS

For the most part, telecommunications via cellular, satellite, UHF and telemetered were largely unaffected (Wilson et al., 2012b). Satellite communications were impacted, but regular cleaning preventing too much accumulation occurring. Some of the finer rhyolitic ash did cause damage to some equipment such as phones and cameras. However, the majority of this was remedied by cleaning with use of compressed air or wiping down with wet cloth.

WATER SUPPLY AND WASTE TREATMENT

The town of Futaleufu used a snowmelt in an upland basin, unprotected from ashfall. The town's authorities choice to disconnect this source due to concern of ash contamination and subsequent risk to the water treatment plant (Stewart et al., unpublished data). This decision was made as a precaution, rather than monitoring data. To manage the demand for water in the short-term, a mobile chlorination plant was used to treat water from a nearby lagoon along with tankered water and supplementary bottled water delivery. In the long-term, a new well was formed to replace the town's principal water source.

In the city of Esquel, Argentina, the water supply is derived from groundwater, which is invulnerable to ashfall contamination (Stewart et al, unpublished data). However, a surface canal is used to transfer from the source to the water treatment facility. The city's residents reported a metallic taste and authorities initiated a water-sampling program. It was found that in comparison to the water being tested from the ground water source, conductivity, sulfate, aluminum and iron were all higher from the canal. No tested water contained chemical levels that were of concern by Argentina water safety levels. The water supply remained at normal pH level of 7.8 despite receiving ashfall (Stewart et al, 2009). Due to testing, authorities issued a statement saying that water posed no health risks (Stewart et al, unpublished data).



See Also:
Power Supply
Transportation
Equipment & Communications > Phones & Radios
Water & Wastewater > Water Supply
Water & Wastewater > Wastewater—Sewage and Stormwater Management in Ashfall