Date Storm ARI Dwellings FloodedProperty Flooded Total Calls 23/07/2009 <5 2 5 24 25/05/2010 3 2 6 28 2/06/2010 <5 1 12 7/06/2010 <5 2 8 37 21/12/2010 9 4 4 28 28/12/2010 20 6 10 10 18/01/2011 <1.3 0 0 na 3/03/2012 1.3 0 0 na 8/08/2012 <2.33 0 9 139 12/08/2012 <2.33 0 0 12 15/01/2013 <5 1 2 21 6/05/2013 9 0 10 48 17/04/2014 <1.5 1 4 60 Table 5 Customer Service Requests During Storm Events 2009-14 ‘Dwelling flooding’ is interpreted as habitable floors of building whether domestic, commercial or industrial. Whilst ‘property flooding’ generally refers to stormwater entering garages, out- buildings, etc that is beyond the scope of expected ponding on sections. The absolute numbers are relatively low but can disguise some significant events to small local communities affected by local storms. For example the storm on 28 December 2010 was much more intense in the northern part of Marlborough. The impact on Havelock, Rai Valley and the small communities of the Marlborough Sounds was very considerable. The storm was less significant in Picton and had negligible impact on Blenheim and the southern part of the region. The rainfall was most intense from midnight on the 27 through to mid-morning on the 28.th th Rainfall intensity, duration and the precedent weather conditions will all have considerable influence on the performance of the stormwater infrastructure and the customers’ experience of a storm event. 4.1.4 Asset Condition The condition of the stormwater reticulation is generally based on the age of the pipes. In general buried pipelines have a design life of 80-100 years. There are many influencing factors on pipeline condition and life expectancy – material, depth of pipe, groundwater level, workmanship of installation, interference from other utilities, surface traffic, ground movement, jointing materials, bedding & surround, etc. These factors may act singly or combine their effects to create difficulty in predicting trends in life expectancy. Pipes can be inspected with the use of closed-circuit television camera. The pipe structural and service condition can be assessed through a nationally recognised pipeline evaluation technique. Currently CTTV is deployed to investigate suspect pipes or to assess the condition of pipes that may require upsizing. It is likely the technique will be used more widely and systematically to support the Blenheim Stormwater Strategy and other areas as strategies are developed. For asbestos cement pipes the life expectancy has been derived from the tables published in the New Zealand Asbestos Cement Watermain Manual (2001). The manual uses data from practical experience gathered throughout New Zealand. The study was confined to water mains and the correlation to stormwater and sewer mains has not been tested. However for medium and large sized pipe the life expectancy is within the 72 year to 100 year range. Table 6 shows the remaining life of stormwater reticulation in the serviced areas. Using the assumptions above it can be seen that less than 2% of the network will reach the end of its useful life in the next twenty years. However the projection would suggest that in the period Page 38