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Our river - It's in trouble |
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Credit: Richard Budd
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Thursday, 06 November 2008 |
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[A long term resident of Heathcote, and ex-councillor for Environment Canterbury, is Richard Budd. He
has taken time out from building a chook house to comment on Rata
Ingram's article on the state of our Heathcote River and Joseph
Burston's response to it. Reading through the problems, you will see
how sad the situation is for our river. What a mess. Thanks Rata,
Joseph and Richard for drawing our attention to it.]
I have had a look at the comments of Rata (Heathcote Valley School) and
Joseph (Green Party) about the Heathcote River: they are good and I
have no issue with them. I completely support the formation of a group
to actually do something rather than just complain about it.
Here are a few thoughts and groans about our river:
The Heathcote has been getting worse for a long time and, as pointed out by Rata and Joseph, there are several reasons for this.
Starting with the headwaters, as Rata's class did, there are already
problems for our river. New subdivisions are supposed to control
sediment during and after construction. Subdivisions out at the
headwaters of the river are still having an effect however. The well
documented Adenfield is a case in point. The penalties imposed for this
kind of breach of the RMA are not deterring this outcome enough.
The potential for damage from subdivision on
the slopes of the Port Hills is worse. The soup that pours from the hill
streams and drains is a disgrace. How can a couple of bails of pea
straw to stop sediment leaving construction sites do an adequate job on
the hill? Yes, report any abuse that you see to the ECan pollution hotline, (03) 366 4663.
Further down, stormwater discharges continue to put contaminants directly into the river from our roads. Urban dwellers are outraged by any rural farm directly discharging a contaminant to a waterway, yet here in town we collect the stormwater from the roads and discharge it directly to our rivers.
During heavy rainfall the city council is allowed by resource consent to discharge untreated sewage to our rivers because the pipes fill with rain and it can't get to Bromley. Imagine a dairy farmer using that excuse! Downstream again, Hansens Park is a restored rubbish dump. It has a resource consent to discharge contaminants to the river and will do so for many years.
In Woolston, just upstream from Heathcote, the Woolston Cut has been described by a previous Parks Manager as the greatest environmental disaster in the city. It was developed by the Drainage Board to ease flooding. However, it sits in the tidal zone and I am not sure how effective it is at high tide. The bed was not capped and soon after salt started appearing in the aquifer. By removing water from the aquifer, the hydraulic pressure drops, and lets the newly available saline water in.
The Woolston Cut also allowed the tidal influence to travel much further up stream, above Hansen Park. A salt crab invaded the banks of Richardson Terrace up to Opawa Road. This destabilised the banks and the city council applied gypsum, as well as placing shingle in the river to help support the banks. This was a major impact on the ecology of this part of the river.
Growers in Horotane Valley had real problems using this salty water, especially with lettuces. The city well was closed to reduce the pressure loss and stop salt migrating downwards to the aquifer. After several years, the salt levels began to drop.
Getting closer to our neighbourhood, the industrial area at Woolston used the river as a sewer. There were two large tanneries as well as heavy industry that piped their waste directly to the river. There are many (20 odd) closed landfills in this area and no one really knows what is buried there. A good guess is that it will not be pretty. This stretch of the river finds heavy metal contamination in the sediments. We have no idea how long contaminants will leach into the river.
We think these things stopped years ago but it is likely that old landfills still discharge to the river. Only a few years ago a toxic waste dump was discovered where industrial waste had been collected after supposedly being removed from industry and treated for disposal. The containers this stuff was in had corroded and were leaking into the soil. After rainfall the surface water would pick up these contaminants and discharge them to the Heathcote just across the road. The regional council found out the land was leased from the city council.
Recently, the new retention ponds on the Heathcote Valley floodplain, that we all love, did a similar thing to the Woolston Cut. They were excavated up to 5 metres deep straight into groundwater, without discussion with the regional council who have concerns about the effects of this. Especially as the excavation dug into marine sediments: you can see shells everywhere.
The idea of stormwater detention is great to stop sediments getting into the river, but have you seen the sediment trap at the discharge of the second pond? It's nothing more than a piece of shade cloth that long ago ceased to even cover the discharge, let alone do anything.
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