Table 9 Summary of system design and impacts for infrastructure after the 2011 PCC-VC eruption
Infrastructure | Towns | Design | Impacts | Main issues |
|---|---|---|---|---|
Electricity | Villa la Angostura | Not connected to national grid; 6.1MW thermal generation plant | Flashover on 13.2 kV, 380 V, and 220 V networks due to damp ashfall; Dry ashfall clogged air intakes for the thermal plant resulting in precautionary shutdowns | Flashover; air intake clogging |
Bariloche | Single transmission line and one grid exit point from national grid; Outdoor GXP substation | Whole town lost power for 8 h, with some not reinstated for 24 h after the initial ashfall; power cuts due to GXP substation suffering flashover due to ash; contamination of switches and busbars; diesel and gas generators were deployed around the town but the air intakes became blocked with ash | Flashover; air intake clogging; switch abrasion; generator blockage | |
Jacobacci | Single transmission line and one grid exit point from national grid; Outdoor GXP substation | Some flashover caused intermittent power cuts to the town (usually for only a few hours); Tripping of switches due to flashover and abrasion of metallic components | Flashover; switch abrasion | |
Water Supply | Villa la Angostura central system | Town centre supplied by Lomas del Correntoso treatment system. Water is extracted from Lago Correntoso and Lago Nahuel Huapi then pumped up an 80 m rise to the WTP. An initial filtration step is followed by pressure sand filtration then chlorindation then gravity fed to households. | The eruption increased the level of suspended ash in the lake, which caused high levels of wear and tear on pumping equipment. Power outages also caused problems for this system. | Turbidity increase; damage to pumping equipment |
Villa la Angostura peripheral systems | A range of smaller systems based on intakes from streams or the lake. Systems are generally gravity-fed. System designs vary considerably, but in general the stream-fed systems are poorly maintained and do not achieve a good level of sediment removal prior to chlorine dosing. Water supplied to households may not contain adequate chlorine residuals. | Stream-fed systems were severely affected by the eruption, with intake structures inundated with ash. These systems continued to experience problems in rainy conditions when further ash was washed downstream. Some systems have been abandoned. | Damage to intake structures; turbidity increase; other contamination of raw water source; clogging of filters; overall system failure | |
Bariloche central system | Bariloche’s central water treatment plant has an intake in Lago Nahuel Huapi. Water is pumped up a 150 rise to storage tanks. The treatment process does not include a preliminary coagulation/flocculation step as intake water is normally very low in turbidity (0.2–0.4 NTU). Filtration is through open-air slow sand filters prior to chlorination. | The eruption increased the level of suspended ash in the lake, which not only caused accelerated wear and tear on pumping equipment but also allowed ash to enter the treatment plant (both via the intake and by direct fallout) where it clogged open sand filter beds. A greatly increased level of maintenance was required to manage these problems and remain in production. A city-wide power outage caused an interruption to water production. | Turbidity increase; damage to pumping equipment; clogging of filters | |
Bariloche peripheral systems | Similar to range of smaller systems in Villa la Angostura; outlying neighbourhoods supplied by smaller systems with intakes from springs, streams and the lake, with wide variety of treatment system design. | Effects were similar to, though less severe than, for Villa la Angostura. | Damage to intake structures; turbidity increase; clogging of filters | |
Jacobacci | 17 groundwater wells with well-head pumps enclosed in pumphouses; water then chlorinated and distributed | This system is completely enclosed and thus proved resilient to the ashfall. However problems were experienced with high water demand as the town was repeatedly subjected to wind-remobilised ash and additional water was required for clean up | A sustained increased water demand | |
Waste water | Villa la Angostura | Not investigated during field visit | - | |
Bariloche | Treatment plant 4.3 km east of the city; pumped to plant then screened through 25 mm bars, pumped through a decanter, then through a anaerobic tank before entering the biological reactor (Nocardia spp. Bacteria), finally wastewater sludge is separated and taken to the dewatering plant | Solids coming into the plant increased from 4500 mg/L to 8000 mg/L in the 3 days after the eruption due to ash contamination; sewer lines and storm drains were meant to be separated but sometimes illegally connected which meant large volumes of ash entered the system; power cuts meant that pumping stations without generators stopped; pump impellers had accelerated wear; 1 m of ash accumulated in the bottom of the 4.5 m deep biological reactor which reduced the plants capacity | Blockages of stormwater catchpits and sewer lines and junctions; accelerated wear and tear to sewage pump impellers; power outages affected pumping | |
Jacobacci | Not investigated during field visit | - | ||
Roading | Villa la Angostura | Asphalt main roads, unsealed secondary routes | Route 231 (asphalt) connecting Villa la Angostura with Bariloche was closed after the eruption for a day, then reopened but with speed restrictions; the Samore Pass border between Chile and Argentina was closed for several weeks after the eruption due to the thickness of ash recieved (>300 mm); drivers reported a loss of traction, inability to see road markings, and some issues with air filters becoming clogged | Road closures; road markings not visable; loss of traction; air filter clogging |
Bariloche | Asphalt | Route 40 (asphalt) the main road into Patagonia was closed for two days after the eruption; main road within the town were covered with 50 mm of ash therefore authorities recommended that cars stayed off the road | Road closures; road markings not visable; loss of traction; air filter clogging | |
Jacobacci | Predominantly unsealed | Visibility an issue due to wind remobilisation, this prevented almost all driving and clean up for the first week; road between Jacobacci and Bariloche closed for a few days, then reopened to limited traffic at low speeds | Road closures; low visibility; road markings not visable; loss of traction; air filter clogging | |
Airports | Bariloche | Fourth largest airport in Argentina; located 13 km outside of Bariloche; airport land covers 1,810 Ha with a 2,400 m runway | Airport was closed for a month due to ashfall; approximately 1000 tonnes of ash was deposited onto airport land; when the airport reopened some airlines (LAN Chile and Aerolinas Argentina) did not recommence flights due to fears around ashfall and accurate forecasting; full service resumed on 20 December 2011 | Airport closure; airlines reluctant to resume flights |