68 | nzdairy DAIRY SERVICES » Irrigation New Zealand Much-needed clarity to dam safety Richard Loader Recent changes to New Zealand’s dam safety regulations have brought much-needed clarity for farmers, but concerns remain about compliance levels as the 14th August compliance date has passed. “This doesn’t change the way low risk dams are managed as in these cases they don’t really need much more attention,” says Stephen McNally, Irrigation New Zealand Principal Technical Advisor. “But any dam owner that finds themself with a medium or high PIC probably should probably have been giving the structure some attention, especially around wave erosion on the upstream face, spillways and downstream slump of the wall. Any obvious leakage should have been sounding a warning bell. I’ve asked a couple of dam owners if they have a spillway for flood overtopping and in some cases they didn’t know if it had one or it had been damaged over the years with vehicle and stock movement. Some dams have also had plantings on the downstream face which can pose a risk of roots creating seepage failure pathways.” The Ministry of Business, Innovation and Employment (MBIE) estimates approximately 1,100 dams exceed the regulatory threshold. However, as of late October, only about 450 dams had registered their dam compliance certificate with regional councils, highlighting a significant compliance gap. “We estimate there might be more dams than currently recorded, as the database might not be very accurate. Our concern is that if farmers are non-compliant, it may affect insurance and lending packages with the banks if they have a non- compliant activity on their farm.” The regulations underwent crucial modifications in March, following industry feedback. The revised threshold now excludes dams under four metres in height and 20,000 cubic metres in volume, effectively removing approximately 2,000 small farm dams from the regulatory requirements. “Some dam structures have been around since the seventies. In a seismic event or extreme rain event, these dams could let go ,” says Stephen. “What the engineer does is examine what would happen if the dam failed. Are there people living near the dam? Are there environmental aspects or roads and highways at risk?” The compliance process requires dam owners to engage with recognised dam engineers, a requirement that presents both practical and financial challenges. Stephen McNally, Irrigation New Zealand Principal Technical Advisor. “There aren’t that many of these people, and farmers might not be used to engaging with that sort of professional to do the work,” says Stephen. “One of the quotes I heard from a farmer is that the bank might lend them $7,000 for this year’s seed but was unlikely to lend them that money for an engineer’s report.” The regulations align with international best practices and have been developed in consultation with the New Zealand Society on Large Dams. For most farm dams, the assessment is likely to result in a low-impact classification, requiring reassessment only every five years. However, medium to high-risk assessments necessitate the creation of a Dam Safety Assurance Programme. To assist farmers with compliance, efforts are underway to develop accessible guidance materials including the development of self-assessment tools to help farmers evaluate their risk levels and potentially reduce costs. There are also resources available on the Building Performance website under dam safety resources. www.building.govt.nz “As a sector body, we will continue to work with MBIE over the implications of the regulations and pragmatic solutions,” says Stephen. “But we are advising farmers not to ignore things as the risk of non-compliance remains significant, with regional councils having the authority to fine dam owners who fail to meet their obligations. Farmers who have not already met the regulations need to have a conversation with their regional council and engage with a recognised dam engineer.”
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