Informatics Publishing Limited

Rahul R. Biswas ¹

Affiliations
1 Department of Asset Management and Planning, Christchurch City Council, Christchurch, NZ

Abstract

Objectives: This paper demonstrates how hydraulic models were built and calibrated for the 2018 post-rebuild hydraulic model and the 2018 no-earthquake hydraulic model for Christchurch’s wastewater network to evaluate the success of the post-earthquake rebuild work in returning the Level of Service (LoS) of the wastewater network to the no-earthquake level. Methods: Info works ICM (Integrated Catchment Management) and Infonet hydraulic modeling tools were used for this investigation. The models were developed taking Christchurch’s sewer network information such as the network survey files, GIS sewer network files, Closed Circuit Television (CCTV) inspection information and flow-monitoring data. Findings: Wastewater network hydraulic models were found to be very powerful tools that can combine different network information (GIS, CCTV inspection data, surveys and flow-monitoring data) into a meaningful platform and predict the performance of the network for different development scenarios. This paper successfully demonstrates how hydraulic models were developed and used to assess and compare the performance of the rebuilt sewer network with the no-earthquake sewer network of Christchurch. As per the model simulation results, there will be less wastewater overflow in the post-rebuild network when compared with the no-earthquake network. Application/Innovation: Sewer network hydraulic modelling is traditionally used for concept design and future planning, or programming for wastewater network. In this research, hydraulic models were developed and used in an innovative way to assess the success of multimillion dollar rebuild works.

Keywords

Earthquake, Rebuild, Sewer Network, Sewer Performance, Wastewater Network, Hydraulic Model

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Rahul R. Biswas ¹

Affiliations
1 Asset Management and Planning, Christchurch City Council, Christchurch, NZ

Abstract

Objectives: The effects of earthquakes on a sewer network can be assessed using different well established methods such as flow monitoring, visual inspection, condition assessments and engineering survey. The main objective of this study is to investigate how hydraulic models were developed and used to assess the immediate devastating impacts of seismic activities on Christchurch’s sewer network. Methods: Infoworks ICM (Integrated Catchment Management) and InfoNet hydraulic modeling tools were used for this investigation. Two hydraulic models (2010 pre-quake model and 2011 post-quake model) were developed for Christchurch’s sewer network as part of this assessment. Findings: Hydraulic modelling was found to be a very powerful tool engineers can use to assess the impact of an earthquake and quantify the performance of sewer network. In Christchurch earthquakes caused significant damage to the waste water network. In post-earthquake Christchurch, there was an increase of 33% in the flows to the treatment plant due to earthquake related damage in the network. Application/Innovation: This paper summarizes hydraulic-model building and calibration works for pre-earthquake and post-earthquake Christchurch to evaluate the impacts of seismic activities on the sewer network. This paper suggests that any modern water authority could implement appropriate hydraulic modelling strategies and modelling tools to prepare for any unforeseen situation.

Keywords

Earthquake, Infoworks ICM, Modelling, Seismic Effects, Sewer Network

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