Halswell Domain

Halswell Domain
View from the Model Engineers' site in the Halswell Domain

Wednesday, October 20, 2021

Time to think about how we move around town?

Petrol prices are rising again as much of the world comes out of Covid-related lockdowns and pushes up demand for petrol, diesel, oil and aircraft fuel.  Many pundits predict that prices will continue to rise over the next few months, and potentially years. As such it is a good time to be considering how to cut down our car running which the IRD estimates  as being 79c per kilometre (not including the cost of parking). 

The best way to make changes to something as regular as your transportation mode is to set small goals such as changing how you travel one or two days per week or trying out a couple of trips using a different way of getting around.  Small steps like this can help you work out what works for you and your family.  Here are some options: 

  • Try ride sharing – travelling with others living nearby or who can pick you up on their way to your destination.  Don't immediately try it everyday - start small and see how it goes then add on more trips if it all works.
  • Catch a bus:  You may need to think about changing buses or about parking near a bus route and catching the bus.  If you have to drop kids at school take the bus after dropping them off.   Check out the Metroinfo website for more information and timetable or pick up paper copies of timetables at Te Hāpua. You can also buy a Metrocard at Te Hāpua or order one online to save on your bus fare.
  •  Dust off that bike in the garage.  The secret with cycling is to be open to trying new routes from those you might use in a car.  There are many cycleways and cycle lanes and many quiet streets that are good for cycling and which can connect up cycleways.  Pick up the latest CCC cycle map for free from Te Hāpua or find it online.  
Bike trailer
Photo: Steve Muir
Bikes are easy to park and are frequently the fastest way to get to your destination.  Equip your bike with a carrier and a pannier bag and you can carry whatever you need.  A good lock is  important.  Trailers also make bikes really useful and fast for shopping trips or for transporting the dog.
Another good option is to mix and match your bike with other transport - driving some of the

Try mixing and matching your bike with other transport - driving some of the way and biking the rest can cut parking costs and be a good way to start biking.  Likewise, putting your bike on a bus (bikes travel free) can be a good way to extend the distances you can cover on a bike.  Find more about bikes on buses here.

  • Buy an electric bike:  More and more people are using electric bikes and electric cargo bikes.  The addition of electricity makes cycling easier and more fun, and significantly extends how far you can travel.  Electric bikes can be quite expensive to buy but they quickly pay themselves off because they are so cheap to run.  Many people who ride e-bikes say that they replace a second car.  Both E-bikes and ordinary bikes provide physical and mental health benefits and are great for work productivity.
  • Buy an electric car:  The up front cost of  an electric car may put electric cars out of reach but if you travel significant distances each week where buses and bikes may not quite cut it, they may well pay for themselves in petrol savings.  It is worth doing the sums to check it out.    

Thursday, September 30, 2021

Water and Waste

At our September meeting, we welcomed Mike Bourke from Christchurch City Council to our Monthly Connections Meeting. Mike answered questions about the water issues/solutions in the Halswell ward and the three waters reform. Mike is the Senior Technician, Water & Waste Planning at CCC.\nHe described what the 3 waters reform meant for Christchurch \n and for Halswell as well as issues around chlorination, water shortages, metering and charging for water.\nMike outlined the progress CCC is making on upgrading the infrastructure to try and keep chlorine out of the water and how waste and storm water are managed. As part of the discussion we also discovered that water can be dated! and that this is a crucial piece of information in the fight to keep Christchurch water free of Chlorine.


What does the 3 waters reform mean for Halswell?

The 3 waters reform is a government initiative to ensure safe water to all New Zealanders and came into being after the Havelock North e coli incident. It amalgamates all water providers into 4 distinct entities which takes control out of the hands of elected members and effectively puts it in the hands of a company.

One issue not yet clear is who then owns the assets. Current and future citizens of a city will be paying for the assets but how will that be recognised?

What happens if the government does take this over?

This is one of the key things to work out going forward. Mike outlined that the current system was unfair as it stands as water rates are based on CV of the house not the amount of water used. The new entities and the assets will be regulated but the costs in doing this are as yet unknown. It is however unlikely to save any money.

The council have started charging for excessive water use ovr 700l a day. Its a start to make people value water but currently a single person can be paying the same for their water as a large family if the house value is the same.

How do the council charge for wastewater?

This is based on the proportion of the water used by the house.

Is Christchurch short of water?

Not currently. Christchurch draws its water from huge underground resources which have an estimated capacity of 75 million m3 . Currently we draw around 55 million m3 which is well within capacity but with continued growth we could get there.

Mike agrees with the idea that we should be paying for water in some shape or form simply so that people value it more as a resource - like they do internet, phone etc.  There are different options in this. For example households could pay for every cubic metre used or households could opt in to pay for every m3 if they think they use less than the average designated by the council in the rates. Perth has this as an option for residents.

The problem will always be the societal extremes. Some people who can’t afford it could end up with big bills.

One suggestion would be including water consumption on the rates bill so people could see how much water they actually used.

Do all the new subdivisions have water metres?

Yes. All properties have a metre. Even the older ones.

Will Christchurch water continue to be chlorinated?

Mike said he would like to think not. The problem is the national system compares apples and oranges.  Christchurch is compared to other areas who draw their water from underground, however our water comes from a very different source than Havelock North where the e. coli outbreak was down to extreme conditions and poor infrastructure.  By comparison, Christchurch water comes from deep aquifers and CCC have invested in upgrading the infrastructure to prevent this occurring. For example, bringing the well heads above ground to prevent backflow.

Some wells cant get very deep so are UV disinfected. CCC has never confirmed e. coli from the wells
Having a non return valve on every property prevents backflow into the system.
The concrete roofs on reservoirs need sealing and fixing as the concrete is porous and allows runoff into the water stored inside.
Once these upgrades are finished CCC will put forward their case to the government for no chlorine in Christchurch water. 

What about nitrates? How is CCC working with the regional council on that?

Nitrate levels are a point of discussion. Christchurch levels are currently well within guideline levels but there is research suggesting those levels are still too high. The groundwater that feeds the aquifers comes from water flowing from Halkett/West Melton and North Canterbury flowing under the Waimakiriri river

ECAN are currently looking into rising NItrate levels that could be coming from North of the Waimakiriri as high levels have been detected north of the Waimak and that water flows under the river into the Christchurch groundwater

The underground water is filtered by both abiotic and biotic systems. Natural filtration removes most suspended matter from groundwater as the water passes through porous layers of soil and rock into the aquifers. Biotic factors are affected by high levels of nitrates which is why it is so important to monitor and reduce these levels.

Snow melt does end up in the Waimakiriri but not much recharges the aquifer as once it passes Halkett the water surfaces and runs off to the sea.

Water monitoring / dating.

Mike explained that water can be dated! In order to draw from the underground water, monitoring has to show that the water in the wells is at least 2 years old. Thi sis done through carbon and tritium dating and modelling can tell where the water entered the system and when. Some of the water in the wells is 175 years old.

Water Reform Costs? The government say the reforms will save us billions. Where do the savings come from?

How will the government do the same thing as the councils and do it cheaper?

The reforms will improve water for smaller, rural centres, not for the bigger centres like cities. The reforms aim to reduce the huge gap in NZ betweenthe top and bottom of water quality and access.

The savings would presumably come from the reduced levels of management. Whether this is a good or bad thing is up for discussion.

There is so much work to do in some regions and communities that it cant possibly save money.

Ross raised concerns that Christchurch water assets are worth $6.9 Billion with $1.1 Billion in debt meaning a net worth of $5.8 billion yet the government are offering Christchurch $122 million. There is a clear inequity in the argument when other communities who have not invested in their infrastructure are being offered similar amounts of money for assets worth far far less.

Ross also questioned whether the costs paid by developers would remain in the local area as if water is no longer controlled by the local council these fees would end up elsewhere in the country. Whilst he was certain most people would not have an issue subsidising the infrastructure upgrades in rural areas for example, he though people would have an issue with selling $6.9 billion of assets for $122 million!

Another issue raised was that of stormwater. Especially in Christchurch where swales and retention basins are an integral part of the landscape, parks and green spaces. How will they be managed if the council no longer control them.

Mike agreed that there were a number of issues the government had yet to address:

Ownership of assets

What's going on with Stormwater in the area?

New developments are responsible for managing the stormwater that development will generate. The idea is that they develop systems to mitigate the runoff so that it would be no more that that generated by the site in its undeveloped state.

The big storm in May 2021 suggests that the mitigation works. Flooding was far less than in previous events before the retention basins and wetlands had been developed.

When developing a site the developer needs to tak into account the wider basin and the impact any building may have on that, particularly since the earthquakes raised the groundwater levels in the area..
This is why long term land use plans are so important and cant just be changed as any change of use can impact another area.

Mike suggested that every household should have a stormwater system to collect the rain off the roof and reuse it.

Any truth to the rumour that the Sutherlands retention basins are over allocated?

Mike wasn't sure about this but probably not.


Can you use Pressure sewage tanks to collect and pump out storm water?

No. Definitely not. This is a myth. People see the tanks and think they are for stormwater but they are only for wastewater

In TC1 areas sewers have been replaced by pressure sewage tanks which are more robust and can be pumped out if needed



Tuesday, August 24, 2021

Halswell and Water

Halswell is an interesting spot in terms of drainage.  

Water drains west down to Te Waihora Lake Ellesmere from some parts of the area while, from other parts of Halswell, it drains east down into the Ōpawaho Heathcote River.  Aidanfield and the areas around the Domain drain east, while Westlake, Oaklands, Country Palms, Knights Stream and Longhurst all drain west via the Huritini Halswell River.  Rain that falls around the area therefore can contribute to flooding in both directions in heavy rain.

View of Wigram showing the coverage of impermeable rooftops

Built environments, like the City of Christchurch, have a lot of hard, impermeable surfaces that don't allow rain to soak into the ground.  This includes roof areas, and asphalt or concrete.  The Ōpawaho Heathcote in particular has been increasingly subject to flooding from rain events as the area of impermeable surfaces has grown.  This is because it drains a lot of low lying land in the City and because our climate has changed over recent years.  We are having more droughts and fewer but bigger rain events rather than many small ones.  

The City Council is addressing this in a number of ways.  One is that for infill housing in some parts of the City, developers must put in tanks that collect water in a flood event and release it slowly after the event.  You too could assist that process by putting in rainwater tanks which can be used to water gardens, or, if you are really keen, might be plumbed into your toilet to help cut down your water use in the summer months but which fill during rain events and hold some water back.  

Wetland area Cnr Sparks and Henderson's Road
Another way that flooding is being managed in both directions is through the development of water retention areas.   In this, Halswell is very important, as we can see from water retention ponds and areas that fill with water when it rains.  You can see these in the Wigram Basin, around Aidanfield, in Ngā Puna Wai in the Halswell Domain and in Henderson's Basin - along either side of Sparks road and Cashmere Road.     

Halswell Quarry in a flood

Water retention areas are also visible around Quaifes Road and Saby's Road, along the bottom of the Hill to the Quarry where a lot of water is held back from the Huritini Halswell River.  More will be built as development in this area continues.  Selwyn District Council is going similar work around Lincoln, Prebbleton and Tai Tapu as those areas develop.

Full retention areas near Living Waters Cnr Dunbars and Halswell Roads

The bonus for us here in Halswell is that we have a lot of very nice green spaces that have been and will be planted out in natives and which are great places for walking and biking.