{"id":71279,"date":"2025-10-11T03:36:09","date_gmt":"2025-10-11T03:36:09","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/71279\/"},"modified":"2025-10-11T03:36:09","modified_gmt":"2025-10-11T03:36:09","slug":"stormwater-solutions-lying-in-the-soil","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/71279\/","title":{"rendered":"Stormwater solutions lying in the soil"},"content":{"rendered":"

Sue Ira has brought her spade along to an appointment with The Detail.<\/p>\n

But she didn\u2019t have to do much digging to provide a stark demonstration of the problem she\u2019s researching \u2013 the effect tightly compacted ground has on soaking up water and encouraging trees to grow tall.<\/p>\n

The Auckland University PhD candidate, director of consulting company Koru Environmental, and industry expert in water-sensitive design is trying to raise awareness of how we treat the most fundamental rain sponge in our cities \u2013 soil.<\/p>\n

In the Auckland suburb of Panmure there are ample examples of the problem, including on the day we were there, another block being levelled and compacted.<\/p>\n

In the shadow of Mt Wellington\/Maungarei you would expect rich volcanic soil, and that\u2019s just what Ira\u2019s spade reveals when she cuts a turf block in an established area. Directly across the road though is a brand-new development of tightly packed townhouses. There, it\u2019s a different story.<\/p>\n

In a nicely landscaped and barked raised garden planted in native shrubs, the soil is much harder to dig down into. There\u2019s just a slither of topsoil and underneath the dirt is tightly compacted, turning grey (a sign there\u2019s not much air in it) and looking more like clay and rubble than soil.<\/p>\n

\u201cIf you feel that, it\u2019s kind of sticky,\u201d she says. \u201cWhereas the other soil was quite crumbly.<\/p>\n

\"\"The soil found in new development areas has often been compacted so tightly that it\u2019s lost all its nutrients and sponge-like capacity to absorb water. Photo: Davina Zimmer\"\"Sue Ira says healthy, uncompacted soils are nature\u2019s quiet way of keeping the water cycle working as it should. Photo: Davina Zimmer<\/p>\n

\u201cYou can see it\u2019s really hard to get down any deeper.<\/p>\n

\u201cSo what we\u2019re seeing with these sort of areas is developers are putting a lot of this bark mulch on because it makes it look nice, raises it all up \u2026 but of course that just decomposes over time and shrinks, so there actually ends up being very little topsoil on top of the subsoils as well.\u201d<\/p>\n

Ira says the landscapers have done a good job \u2013 \u201cbut the execution is wrong, mainly because of what\u2019s beneath their feet. And that\u2019s not necessarily the developer\u2019s fault or the council\u2019s fault or anyone\u2019s fault, it\u2019s just a lack of knowledge as to what needs to be below to support healthy vegetation.\u201d<\/p>\n

She predicts that at the first sign of a dry summer the plants will start to die off.<\/p>\n

Nearby is a narrow green strip featuring coprosma ground cover but it\u2019s planted in a miniscule amount of dirt.<\/p>\n

\u201cThere\u2019s probably less than 200mm of depth for those plants,\u201d she says. \u201cSo they might look ok now because they\u2019re small, but they\u2019re really going to struggle come any sort of drought. Then what happens is these areas just become weed patches, they get either concreted over or sprayed, and that gives any nature-based solution a bad name because \u2018Oh look, it doesn\u2019t work\u2019. But it\u2019s the way we\u2019ve applied the solution again that\u2019s not working, not the solution itself.<\/p>\n

\u201cIt\u2019s a nice idea to break up the pathway and the driveway. But rather, have the vegetation all on one side so you have a bigger, more resilient strip.<\/p>\n

\"\"A building site in Panmure where an entire block has been cleared to make way for a new housing development. Photo: Davina Zimmer<\/p>\n

\u201cThe problem is \u2026 often these developments happen, and they\u2019re handed over to council and the developer\u2019s gone. And so it doesn\u2019t really matter what it looks like in a few years\u2019 time. The lots have been sold, the houses have been sold and built.<\/p>\n

\u201cOur plans and our policies need to be improved by making the developers, the consenting process, think about the long-term implications of their developments.\u201d<\/p>\n

Ira says natural disasters including Auckland\u2019s Anniversary weekend floods in 2023 and the Christchurch earthquakes have prompted some regions to re-think flooding issues.<\/p>\n

\u201cIt\u2019s really daylighted the issue of flooding, not just for council but for the public,\u201d she says.<\/p>\n

\u201cHopefully what that means is that people will take issues to do with stormwater more seriously. <\/p>\n

\u201cIt\u2019s also had an impact at the political level, which is really good, because it wasn\u2019t just Auckland that was affected, we had Cyclone Gabrielle quite close after.<\/p>\n

\u201cWhat that means for our country as a whole, there\u2019s an understanding now that we can\u2019t just leave our stormwater systems as they are. We need to renew them. We need to be thinking of doing things in a different way.\u201d<\/p>\n

Check out how to listen to and follow\u00a0The Detail\u00a0here<\/a>.\u00a0\u00a0<\/p>\n

You can also stay up-to-date by liking us on\u00a0Facebook<\/a>\u00a0or following us on\u00a0Twitter<\/a>.\u00a0<\/p>\n

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