Infrastructure Strategy 4. EARTHQUAKES • New reservoirs have been built to be earthquake resistant and older reservoirs A significant earthquake in the next 50 years (on have been strengthened. Some damage from a very large event must be the Alpine Fault) has a 50% likelihood of anticipated occurring, and an 85% likelihood of occurring There is 138kms of asbestos cement pipe with an estimated replacement cost of over the next 100 years. This event could be 10 • times more powerful than the November 2016 around $26M with a life expectancy of less than 40 years event, with shaking lasting up to six minutes Wastewater (compared to up to two minutes during the Kaikoura earthquake). • The wastewater treatment plants at Blenheim and Havelock are located on the coastal plain. Tsunami inundation is a risk. As is ground movement and To prepare for such a large earthquake, new infrastructure is being built to high liquefaction on river/coastal soils. standards, and emergency power generation is provided for new plants. The Council has also assessed the impact of a significant earthquake on roads, riverbanks and • Many pump stations have been upgraded to resist the effects of ground shaking stopbanks. but significant damage could be expected from a very large event. Fault lines will need to be avoided when developing land and installing infrastructure. • Modern plastic pipe materials are more resistant to damage from ground shaking. Slumping and liquefaction are also becoming more significant considerations when Around 65kms of pipe (valued at approx. planning future urban development. $64M) is over 50 years old. Council has recently reviewed its assumptions and expectations regarding the • Ground movement may affect gravity Maximum Probable Loss to infrastructural assets as a result of a large earthquake. pipelines laid to shallow gradients on the Consultants were employed to undertake a study of probable losses to the three water Wairau Plain services (water supply, wastewater and stormwater) and river defence assets due to an earthquake with a 1:500 and a 1:1000 year return period. An estimate of damage to Roading roading, insurance excesses and losses of rates revenue was also considered. An Many roads particularly in the Sounds and event of this magnitude could result in a $485 million loss to the Council. • rural areas are vulnerable to landslips Currently central government meets 60% (above the excess) of infrastructure damage • Major bridges have been surveyed and strengthened to resist earthquakes but costs incurred from natural disasters. Local government is obliged to show prudent may still be vulnerable to very large events arrangements to meet the remaining 40% of costs. However, central government has indicated it is reluctant to continue this ongoing liability and may wish to pass greater Rivers and Flood Protection responsibility to local authorities in future. The costs of additional risk mitigation could be considerable. The Council maintains a $10m Disaster Recovery Reserve, since the • Many of the older stop-banks have not been constructed to modern engineering November 2016 earthquake analysis is ongoing to ensure the Reserve level is standards sufficient to meet any potential future events in combination with insurance coverage. • The 2016 earthquake caused $2.4M damage to existing stop banks and river Implications for our assets edge protection through lateral spread and slumping Water Stormwater • The water treatment plants for Blenheim and Picton have been upgraded in the • Around 19kms of stormwater reticulation with a combined replacement value of last ten years and are built to the latest standards for earthquake resistance. approximately $10M is of the older ‘brittle ’materials asbestos cement and Emergency power generation is included. The treatment plants at Renwick and earthenware Havelock are less resistant until upgrade works re completed. 2018-2028 Long Term Plan Page 178