Hydroplan is a risk-based engineering methodology developed by Aquafin for the cost-effective management of its underground network assets. Hydroplan is pragmatic, flexible and robust;. It makes only limited use of specific software, and integrates as much as possible databases and model results of the existing network. Therefore, the methodology can be used with a relatively small investment.
The methodology consists of three steps:
- The first step is updating and inventorying the sewer network and performing a strategic analysis to estimate the impact of a possible failure of each sewer. This analysis is done by attributing scores for different aspects of failure impact, e.g. pipe cost, traffic intensity, environmental vulnerability, etc. Several subscores are combined into three scores to indicate the strategic assets, i.e. the parts of the infrastructure which in case of failure would cause major financial, socio-economic and/or ecological damage.
- The second step is estimating the risk of failure for three different failure modes: hydraulic, environmental and structural, taking into account the surroundings and a predetermined frame of reference. The hydraulic and environmental probabilities are determined by means of a calibrated hydrodynamic model. An ageing model is used to estimate the probability of a structural failure of a sewer. Sewer inspections are used to adjust estimated residual lifetime and to adjust the ageing model.
- The third step combines the consequential damage of failure with the probability of hydraulic, structural and ecological failure into risk scores that highlight the most critical points of the sewer network for each of the three failure modes. A short to medium action plan with tailor-made solutions for the critical assets and monitoring and maintenance programmes for the remaining assets is then developed to improve the quality of the existing sewer system in a cost-effective way.