New monitoring of sediment on small sites

By Phil Jones

Why worry about sediment building up in our harbours when the water looks sparkling on a sunny Auckland day? To most of us, it is only when a stream or river turns brown that there is any sign of a problem.

And, is it really a problem? The streams soon turn back to a clear state.

However, the evidence suggests it is a serious, and growing, issue.

As we have cleared land, and developed rural land to house our growing population, the associated earthworks and erosion of stream banks have resulted in thousands and thousands of tonnes of soil entering our waterways.

Over time, the soil particles settles as a sediment layer in our Auckland harbours. The build-up has been significant over the last 50 years. The sediment smothers the habitat of shellfish and other aquatic creatures. Over the years, vast areas become severely degraded. This affects the whole ecosystem, with invasive monocultures or barren areas often replacing a diverse mix of marine life. One effect is fewer of the fish we like to catch and eat.

Auckland Council, and earlier the Auckland Regional Council, have been taking action for many years. But, it’s not been enough. The needs of development and growth have trumped the needs of the environment.

There are very strong signs that is changing.

The Council now has a programme dedicated to addressing the problem. The Strategic Approach to Sediment programme was established in 2018.

One of the key issues the programme is addressing is the soil and sediment escaping from the hundreds and hundreds of small construction sites across the region.  About 800-1000 small sites start construction activities each month!

Sarah Le Claire (Principal Analyst – Natural Environment Strategy) the Council’s programme lead, says “although there are many sources of sediment in Auckland, we identified that the intensity of development in recent years meant that sediment control on small sites was a complex issue that required a collaborative, cross-council approach.”

Council estimates that over half of our disturbed land by area is likely to involve small construction sites.

These smaller sites typically have had weak environmental controls. They generally have ‘permitted activity’ status, meaning that there has not been any proactive monitoring and enforcement. Council is not able to charge for monitoring permitted activity, so the bad practices of some sectors of the building industry cost all Aucklanders, as well as the environment.

Until recently, unless a problem has been reported to Council, the system has relied on construction site workers and management to install effective sediment control measures. Often this has not been done, either due to a lack of awareness and knowledge, or a lack of incentives (or disincentives) to comply.

The Council’s ‘Close the Gap’ initiative is changing this.  It aims to establish cost-effective mechanisms to ensure sediment controls are in place on all small sites prior to any land disturbance activity and remain in place throughout construction.

The initiative has been running over the winter period, from May to August this year.

Initial site visits confirmed the scale of the problem. Visits to almost 1000 small sites during May and June showed high levels of non-compliance, with 88 per cent of the small sites that had started works having either no sediment controls or inappropriate sediment controls in place.

There are now two dedicated compliance officers visiting all new sites, with the aim to ensure effective sediment controls are in place prior to earthworks. This is supplemented by other measures, including the use of Building Inspectors to report on controls. So, now there is proactive monitoring across the whole life of the site works, a real transformation made possible with funding from the Water Quality Targeted Rate. There are also good resources available to developers (see here).

Early signs are good – the council reports that more sites are ‘doing the right thing’.

The new monitoring regime is embedding the opportunity for enforcement action when poor site practice is encountered. An abatement notice is the first step. If the site remains non-compliant, then an infringement notice is issued. The associated fine is typically $750 for standard non-compliance. Hopefully, the mix of education and enforcement will drive the culture change required for improvements in water quality.

Adrian Wilson, the Targeted Initiatives (‘Close the Gap’) Team Leader, says “when we started targeting small sites in Flatbush 18 months ago, we quickly realised that education was not enough to change behaviour. The Close the Gap project, which is region-wide, has shown that direct action to address sediment related issues at an early stage is the most effective way of preventing harm throughout the build.”

Next step for Council is to improve the control on the larger sites – no time to rest!

So, how can we, as Aucklanders, play our part?

It’s really quite easy – be an extra pair of eyes – look out for sites with poor sediment control (lack of well-maintained silt fences and ‘sand socks’ around nearby drains). If you see a problem, report it to council (here). Make sure you take a photo or video.

This might make you feel like a ‘snitch’. But, isn’t it worth it to help protect our Hauraki Gulf taonga and, indeed, all of Auckland’s harbours?


For more information on Auckland Council’s work, see this recent article.