Manholes and wet-wells had a tendency to ‘float’ in liquefied ground conditions. Ground shaking caused significant damage to linear assets – pipelines and stop banks. Research has shown that certain materials, particularly polyethylene performed much better than some of the traditional materials such earthenware, vitreous clay, un-reinforced concrete and asbestos cement. The Stronger Christchurch Infrastructure Re-build Team (SCIRT) has been generous in publishing its findings and solutions. They have created depository of technical advice and engineering standards that will assist local authorities to design and build more resilient infrastructure in the future. 3.3 Demand Impact on Assets The storm in May 2013 revealed a number flooding incidents in the Muller Road/ Howick Road area of Blenheim. The post event analysis led to further investigation with a detailed CCTV survey. The 600 mm steel stormwater main in Muller was found to be badly corroded and partially collapsed. Subsequently 348 meters of the pipe in Muller Road was renewed with a new 675 mm concrete main. The urban development in the head-waters of Murphys Creek is still being discussed with the stake holders. The alternative to using the creek as a conduit for the stormwater from the new Westwood development is a new pipeline along the New Renwick Road. Two alternative outfalls to the Taylor River have been estimated at $2.3M or $3.3M respectively. The design investigation into the Redwood Street/Town Branch Drain catchment is on-going. However, as part of the integrated management through the Stormwater Action Group a relatively small upgrade to the outfall of the Symons Street Pump Station (a Rivers Department asset) provided significant improvements to the discharge and flow characteristics of the upstream stormwater pipeline. 3.4 Demand Management Plan There is an increasing expectation from community of continually improving services. The capabilities of the stormwater service are only intermittently tested during storm events. It is difficult to explain to the public the relationship between the rainfall event and the service they can expect. This is particularly complex for towns such as Blenheim where some areas are deliberately desigedto aximise surface ponding to aid detention of run-off and roads are designed as secondary flow paths. Others areas need to be drained as rapidly as possible and surface ponding is an indication the service are under pressure. The situation is further complicated in that all storm events have unique characteristics in terms of duration, intensity, distribution and precedent conditions. It is difficult to simplify this data sufficiently to guide public expectation. Frequently the information is not available until after the event making it difficult for the public to prepare. The management of community expectations is currently being tested with the Murphys Creek consultations as described in Chapter 2: Levels of Service. The introduction of the ‘Flood Watch’ interactive maps onto the council web-site has provided benefit to the public by publishing ‘live’ data from the rainfall and river monitoring stations around the region. Whilst the stations are on the main rivers and the service mainly benefits the rural community it is a useful source of information for urban dwellers and helps to distribute contemporary information of storm events. Stormwater management has been a significant issue in the design of the new urban zones to the north and west of Blenheim since the inception of the urban growth strategy. The area was known to have a high water table, there is very limited gradient across the sites and the natural flow is through the existing settlement. Investigations are currently being undertaken to quantify Page 32