New Zealand’s Garden City has the opportunity to re-invent itself from the bottom up.
I’m talking sewage.
Consider the large amount of clean water that is used to carry even a small quantity of human excreta. With each flush, over 10 litres of clean water goes down the drain. This clean water which is flushed down the toilet goes into a traditional sewage system. We reticulate all sewage solids and wastewater in a big network of ceramic pipes for centralised treatment. The Romans had the idea for that first and it was perfected by the British almost 200 years ago. It’s ancient.
In the absence of government support or massive rates, traditional sewage solutions threaten to bankrupt communities. Especially if sewer networks need to be rebuilt.
Traditional sewage systems are atrociously expensive to build today primarily because of the labour intensive drainage network. Sewage treatment plants themselves are relatively cheap. It’s the thousands of kilometres of pipes that cost seriously big money. And where pipes are laid in ground that moves – forget shakes – cracks open up in the pipes letting rainwater in and causing overflows, and letting sewage out polluting more water — invariably rivers and ponds and beachwater.
For more than a decade – as a Councillor - I have immersed myself in Auckland’s sewage problems, projects and costs. I chaired North Shore City Council’s Works & Environment Committee’s recommendation ten years ago to impose a fixed charge per ratepayer of $500 annually to reduce leaks from the city’s fragile sewer network. We debated the issue at length. I suggested – half in jest – that we’d be better off with old style night-cart collection of excreta, central composting, and recycling back to land. At least we’d know it was being collected, and we’d also know it wouldn’t end up on the beaches.
North Shore City ratepayers have invested close to a billion dollars in its sewage system. And it still leaks. Much of Auckland is built on soft Waitemata clays and sandstone. It’s shifting slowly all the time, cracking the sewer network. The damage is slow but it’s relentless. And so are the repairs and the costs.
Much of Christchurch is built on alluvial gravels and sand. Its sewer networks lie in ditches dug into this substrate which liquefies in even a small earthquake. Given the choice of developing Christchurch today as a greenfield site – subject to earthquakes from time to time - engineers today would surely advise against a ceramic pipe based wastewater network.
Ten years ago the Auditor General concluded that “it is difficult for Thames Coromandel District Council to demonstrate that the sewage reticulation option is indeed the best use of ratepayer’s funds.” That report was part of a long running battle between the majority of Cooks Beach lot owners and a Council determined to fix septic tank problems by imposing a traditional reticulated sewage scheme. I know Christchurch City is not like Cooks Beach.
My interest in sewage alternatives has taken me round the world and times have changed, as Sydney Water found when it investigated developments in the United States and Europe, after facing estimates of between $16,000 and $70,000 per lot to connect houses to new centralised sewage systems.
They found that on site wastewater services are used in 50% of lots in Norway and 25% of all lots in the USA. On-site servicing is no longer seen as a temporary measure in the USA where 35% of new city housing developments are now on-site serviced. Beverley Hills in LA is all on-site, and Barbra Streisand was one who lobbied the council to keep it that way. The US Environmental Protection Agency has advised the US government that “decentralised systems, where properly managed, could protect water quality over the long term and do so at lower cost than conventional systems in many communities.”
The most modern systems used in US urban environments combine sophisticated on-site primary treatment tanks, which retain and biodigest solids and need emptying every ten years or so, and small-gauge leak-proof pipes which reticulate the liquid effluent only, to either a centralised treatment plant, or to small local treatment facilities. Some of these use vacuum systems or small pumps to send effluent through leak-proof plastic pipes which can bend and move with ground movement.
While modern centralised wastewater treatment plants in New Zealand are using cleaner technology, the fact is that traditional sewage reticulation pipe networks are dreadfully leaky, and environmental disasters in themselves. Even without an earthquake.
It is difficult to justify their construction and use in coastal environments if the goal is to protect and preserve water quality in the long term.
It is no longer flush it and forget it in Christchurch. Every day people are faced with the personal challenge of what to do with their own, and their children’s excrement. Call it human bio-solids. Right now a system of Portaloos and regular collection is being rolled out across Christchurch.
The collected bio-solids will contain toilet paper and some sterile urine. But will not be contaminated with heavy metal trade wastes that get tipped into the sewer. It will not be diluted with thousands of litres of water. It will be pure. Ripe for composting and re-use. It can be developed into a modern, resilient and responsible sanitation system.
Christchurch has the opportunity to re-invent itself from the bottom up.
Showing posts with label alluvial substrate. Show all posts
Showing posts with label alluvial substrate. Show all posts
Wednesday, March 2, 2011
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Showing posts with label alluvial substrate. Show all posts
Showing posts with label alluvial substrate. Show all posts
Wednesday, March 2, 2011
Garden City’s Cheeky Opportunity
New Zealand’s Garden City has the opportunity to re-invent itself from the bottom up.
I’m talking sewage.
Consider the large amount of clean water that is used to carry even a small quantity of human excreta. With each flush, over 10 litres of clean water goes down the drain. This clean water which is flushed down the toilet goes into a traditional sewage system. We reticulate all sewage solids and wastewater in a big network of ceramic pipes for centralised treatment. The Romans had the idea for that first and it was perfected by the British almost 200 years ago. It’s ancient.
In the absence of government support or massive rates, traditional sewage solutions threaten to bankrupt communities. Especially if sewer networks need to be rebuilt.
Traditional sewage systems are atrociously expensive to build today primarily because of the labour intensive drainage network. Sewage treatment plants themselves are relatively cheap. It’s the thousands of kilometres of pipes that cost seriously big money. And where pipes are laid in ground that moves – forget shakes – cracks open up in the pipes letting rainwater in and causing overflows, and letting sewage out polluting more water — invariably rivers and ponds and beachwater.
For more than a decade – as a Councillor - I have immersed myself in Auckland’s sewage problems, projects and costs. I chaired North Shore City Council’s Works & Environment Committee’s recommendation ten years ago to impose a fixed charge per ratepayer of $500 annually to reduce leaks from the city’s fragile sewer network. We debated the issue at length. I suggested – half in jest – that we’d be better off with old style night-cart collection of excreta, central composting, and recycling back to land. At least we’d know it was being collected, and we’d also know it wouldn’t end up on the beaches.
North Shore City ratepayers have invested close to a billion dollars in its sewage system. And it still leaks. Much of Auckland is built on soft Waitemata clays and sandstone. It’s shifting slowly all the time, cracking the sewer network. The damage is slow but it’s relentless. And so are the repairs and the costs.
Much of Christchurch is built on alluvial gravels and sand. Its sewer networks lie in ditches dug into this substrate which liquefies in even a small earthquake. Given the choice of developing Christchurch today as a greenfield site – subject to earthquakes from time to time - engineers today would surely advise against a ceramic pipe based wastewater network.
Ten years ago the Auditor General concluded that “it is difficult for Thames Coromandel District Council to demonstrate that the sewage reticulation option is indeed the best use of ratepayer’s funds.” That report was part of a long running battle between the majority of Cooks Beach lot owners and a Council determined to fix septic tank problems by imposing a traditional reticulated sewage scheme. I know Christchurch City is not like Cooks Beach.
My interest in sewage alternatives has taken me round the world and times have changed, as Sydney Water found when it investigated developments in the United States and Europe, after facing estimates of between $16,000 and $70,000 per lot to connect houses to new centralised sewage systems.
They found that on site wastewater services are used in 50% of lots in Norway and 25% of all lots in the USA. On-site servicing is no longer seen as a temporary measure in the USA where 35% of new city housing developments are now on-site serviced. Beverley Hills in LA is all on-site, and Barbra Streisand was one who lobbied the council to keep it that way. The US Environmental Protection Agency has advised the US government that “decentralised systems, where properly managed, could protect water quality over the long term and do so at lower cost than conventional systems in many communities.”
The most modern systems used in US urban environments combine sophisticated on-site primary treatment tanks, which retain and biodigest solids and need emptying every ten years or so, and small-gauge leak-proof pipes which reticulate the liquid effluent only, to either a centralised treatment plant, or to small local treatment facilities. Some of these use vacuum systems or small pumps to send effluent through leak-proof plastic pipes which can bend and move with ground movement.
While modern centralised wastewater treatment plants in New Zealand are using cleaner technology, the fact is that traditional sewage reticulation pipe networks are dreadfully leaky, and environmental disasters in themselves. Even without an earthquake.
It is difficult to justify their construction and use in coastal environments if the goal is to protect and preserve water quality in the long term.
It is no longer flush it and forget it in Christchurch. Every day people are faced with the personal challenge of what to do with their own, and their children’s excrement. Call it human bio-solids. Right now a system of Portaloos and regular collection is being rolled out across Christchurch.
The collected bio-solids will contain toilet paper and some sterile urine. But will not be contaminated with heavy metal trade wastes that get tipped into the sewer. It will not be diluted with thousands of litres of water. It will be pure. Ripe for composting and re-use. It can be developed into a modern, resilient and responsible sanitation system.
Christchurch has the opportunity to re-invent itself from the bottom up.
I’m talking sewage.
Consider the large amount of clean water that is used to carry even a small quantity of human excreta. With each flush, over 10 litres of clean water goes down the drain. This clean water which is flushed down the toilet goes into a traditional sewage system. We reticulate all sewage solids and wastewater in a big network of ceramic pipes for centralised treatment. The Romans had the idea for that first and it was perfected by the British almost 200 years ago. It’s ancient.
In the absence of government support or massive rates, traditional sewage solutions threaten to bankrupt communities. Especially if sewer networks need to be rebuilt.
Traditional sewage systems are atrociously expensive to build today primarily because of the labour intensive drainage network. Sewage treatment plants themselves are relatively cheap. It’s the thousands of kilometres of pipes that cost seriously big money. And where pipes are laid in ground that moves – forget shakes – cracks open up in the pipes letting rainwater in and causing overflows, and letting sewage out polluting more water — invariably rivers and ponds and beachwater.
For more than a decade – as a Councillor - I have immersed myself in Auckland’s sewage problems, projects and costs. I chaired North Shore City Council’s Works & Environment Committee’s recommendation ten years ago to impose a fixed charge per ratepayer of $500 annually to reduce leaks from the city’s fragile sewer network. We debated the issue at length. I suggested – half in jest – that we’d be better off with old style night-cart collection of excreta, central composting, and recycling back to land. At least we’d know it was being collected, and we’d also know it wouldn’t end up on the beaches.
North Shore City ratepayers have invested close to a billion dollars in its sewage system. And it still leaks. Much of Auckland is built on soft Waitemata clays and sandstone. It’s shifting slowly all the time, cracking the sewer network. The damage is slow but it’s relentless. And so are the repairs and the costs.
Much of Christchurch is built on alluvial gravels and sand. Its sewer networks lie in ditches dug into this substrate which liquefies in even a small earthquake. Given the choice of developing Christchurch today as a greenfield site – subject to earthquakes from time to time - engineers today would surely advise against a ceramic pipe based wastewater network.
Ten years ago the Auditor General concluded that “it is difficult for Thames Coromandel District Council to demonstrate that the sewage reticulation option is indeed the best use of ratepayer’s funds.” That report was part of a long running battle between the majority of Cooks Beach lot owners and a Council determined to fix septic tank problems by imposing a traditional reticulated sewage scheme. I know Christchurch City is not like Cooks Beach.
My interest in sewage alternatives has taken me round the world and times have changed, as Sydney Water found when it investigated developments in the United States and Europe, after facing estimates of between $16,000 and $70,000 per lot to connect houses to new centralised sewage systems.
They found that on site wastewater services are used in 50% of lots in Norway and 25% of all lots in the USA. On-site servicing is no longer seen as a temporary measure in the USA where 35% of new city housing developments are now on-site serviced. Beverley Hills in LA is all on-site, and Barbra Streisand was one who lobbied the council to keep it that way. The US Environmental Protection Agency has advised the US government that “decentralised systems, where properly managed, could protect water quality over the long term and do so at lower cost than conventional systems in many communities.”
The most modern systems used in US urban environments combine sophisticated on-site primary treatment tanks, which retain and biodigest solids and need emptying every ten years or so, and small-gauge leak-proof pipes which reticulate the liquid effluent only, to either a centralised treatment plant, or to small local treatment facilities. Some of these use vacuum systems or small pumps to send effluent through leak-proof plastic pipes which can bend and move with ground movement.
While modern centralised wastewater treatment plants in New Zealand are using cleaner technology, the fact is that traditional sewage reticulation pipe networks are dreadfully leaky, and environmental disasters in themselves. Even without an earthquake.
It is difficult to justify their construction and use in coastal environments if the goal is to protect and preserve water quality in the long term.
It is no longer flush it and forget it in Christchurch. Every day people are faced with the personal challenge of what to do with their own, and their children’s excrement. Call it human bio-solids. Right now a system of Portaloos and regular collection is being rolled out across Christchurch.
The collected bio-solids will contain toilet paper and some sterile urine. But will not be contaminated with heavy metal trade wastes that get tipped into the sewer. It will not be diluted with thousands of litres of water. It will be pure. Ripe for composting and re-use. It can be developed into a modern, resilient and responsible sanitation system.
Christchurch has the opportunity to re-invent itself from the bottom up.
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