The American Society of Civil Engineers, the U.S’s oldest engineering society with over 150,000 members, has since 1988, published an Infrastructure Report Card. This provides a comprehensive assessment of the nation’s 16 major infrastructure categories, examines current infrastructure conditions and needs, and using a simple A to F school report card format assigns grades, before making recommendations to raise these grades.
The Dams infrastructure section makes for an uncomfortable read, as many of the issues which lead to Dams receiving an overall D Grading, are very familiar to us here in New Zealand.
The report highlights that, the average age of U.S dams is 56 years and increasing, and that the proportion of dams which are ‘High hazard potential’ is growing rapidly, as a result of population growth and development. It also states that ‘These structures are not only aging, but are subject to stricter (safety) criteria because of increased downstream development and advancing scientific knowledge predicting flooding, earthquakes, and dam failure’. The number of High Hazard dams with deficiencies is also reported to have climbed to nearly 15% of the 15,500 total, with estimated remediation costs, an eye watering US$45 Billion.
In recommending that ‘to improve public safety and resilience the risk and consequence of dam failure must be reduced’, the ASCE point out that Emergency Action Planning to mitigate the effects of failures, and increased regulatory oversight are vital. Particularly as over 56% of dams are privately owned. While the review found that the numbers of dams with EAPs is increasing (up to 77% for High hazards dams), the resourcing for state dam safety and deficiency remediation programmes remains very constrained. Interestingly, unlike New Zealand, all US states (except Alabama) have dam safety regulation in place.
The report discusses that ‘Risk-based decision making’ will assist owners and regulators in the prioritisation of the use of funding available to mitigate deficiencies. This aligns with the thinking NZSOLD are promoting through its introduction of “Risk Informed decision making’ as a methodology for dealing with some dam safety deficiencies.
The report goes on to state that broader community collaboration is necessary so that ‘ stakeholders will be better able to support land use decisions, emergency action planning, and maintenance and rehabilitation funding, which will reduce community risk in the long term.’
In, age of dam population, dam ownership profile, rapidly increasing proportion of High Hazard dams due to growth and land use changes, and limited funds to address deficiencies, and especially in the importance to economic prosperity of safe and resilient infrastructure, New Zealand has many things in common with the US, and many of the seven recommendations that ASCE make to improve the grading of the US Dams infrastructure would apply to New Zealand.