Wastewater Pump Station 15 - A Case Study in Asset Reuse and Resilient Design

Pump Station 15 (PS15), commissioned in 1970, conveys wastewater from Woolston to the Christchurch Wastewater Treatment Plant for approximately 40,000 population equivalents. The 2011 Christchurch earthquakes resulted in significant damage to and prolonged wastewater overflow from PS15. The damage observed included reverse graded gravity pipes, shear failure of pressure pipe and service connections at structures and separation of the station superstructure due to different foundation conditions.

Ground improvement provided by a specialist contractor will reduce potential differential settlement between structures and pipes to acceptable levels minimising damage in future large earthquakes. The resilient design elements of the station repair coupled with the ability to reuse large components of an existing asset make this project somewhat unique to the Christchurch infrastructure rebuild. 

Following damaging earthquake events, there is the potential to reuse existing assets by utilising modern construction techniques and by reconfiguring pipeline/system layouts. This requires that realistic designs are produced which quantify and qualify the risks from a construction perspective and involve key construction expertise. Where these risks can be eliminated, avoided or mitigated there is the potential for significant cost savings as part of the rebuild of infrastructure networks.