Sludge Watch ==> New Zealand - history of sewage treatment "The poop on poop"

[Maureen Reilly]

Sludgewatch admin:

This brief history of sewage treatment in a part of New Zealand quite 
accurately describes the problem:  "Modern" sewage treatment allows alot of 
contaminated water and sewer overflow to run out into the water...and the 
contaminated solids removed from that water are then contaminating the 
hinterlands while 'fertilizing' the the fields.

If our domestic sanitary wastes were not mixed with water but composted 
(like in a composting toilet) then we would be conserving our drinking water 
(instead of mining irreplacable supplies from underground) and protecting 
surface waters, farm soils, and the food chain.

..............................................



The poop on poop

Nobody wants to think about it, but every community has to deal with it. 
We're talking about sewage here and as Rob Maetzig backgrounds, New Plymouth 
has been rather efficient in that regard.
- Taranaki
Saturday, 29 December 2007







Twelve metres under central New Plymouth there are two huge chambers. 
Combined, they are close to 300m long and extend on an angle from close to 
the foreshore to Molesworth St. They are 4m in diameter, easily large enough 
to accommodate a small army of fully grown men ... not that anyone would 
have ever wanted to be in there.

That's because, for more than half a century, these chambers handled that 
most distasteful of byproducts of any community: sewage.

The chambers are closed off now, access barred by retaining walls built as 
part of the city's coastal walkway.

But they're there, all right, a hidden reminder that for almost its entire 
history, New Plymouth has been impressively forward-thinking in providing 
the right facilities for disposal of its waste.

It wasn't at the start, though. For the first 65 years of its existence, New 
Plymouth had no public sewerage system. Instead, every property at first had 
its own long-drop toilet, then progressed to earth closets that were 
regularly visited by workers with the so-called night carts that took the 
waste away.

Unfortunately, the workers didn't take the waste very far. They dumped it 
into the Huatoki and Mangaotuku streams. And this, accordingly to popular 
history of New Plymouth, resulted in a number of epidemics of the 
often-fatal diseases typhoid and cholera.

One only has to wander through cemetery areas at Te Henui and in the St 
Mary's churchyard to spot sobering references to many young children and 
sometimes entire families killed by these diseases.

Something had to be done. Initially, the health authorities responded by 
dedicating an unpopulated area near the Waiwhakaiho River (now Peringa Park) 
as the official disposal site for what was known as night soil.

But at the start of the 20th century, the New Plymouth Borough Council 
installed the community's first public waterborne sewerage scheme. This 
consisted of about 16km of sewers in the central part of town that drained 
to a communal septic tank near where the rest rooms on James Lane are. From 
there, the partly treated effluent discharged into the Huatoki Stream.

Although this worked well enough and was at times extended, New Plymouth 
continued to grow, and in 1927, the borough engineer Mr C. Clarke created a 
comprehensive and far-sighted sewerage scheme.

The scheme consisted of the two chambers in central New Plymouth, which were 
known as liquefying chambers and were essentially huge septic tanks, and 
they were connected to two main sewers that headed east and west. A series 
of trunk mains then connected to these sewers.

Mr Clarke's system was created at a time when New Plymouth's population was 
just 16,000, but he designed it to cater for a city the size of 60,000. That 
meant the scheme, which was completed in 1933 at a cost of $317,000, was big 
enough to function successfully for 52 years.

The only real change that took place over the years was that the main sewers 
and some of the trunk mains were duplicated and extended. Even then, the 
work was done with the future in mind.

This was particularly the case with the duplication of the main sewer west, 
which also saw it extended to Whaler's Gate so that communities such as 
Oakura could also eventually be included in New Plymouth's sewerage network.

There was one major failing with New Plymouth's sewerage system of the time, 
however: it poured raw sewage out to sea.

Those two liquefying chambers stored and broke down all the solid wastes 
while allowing the liquid to flow out to sea via an ocean outfall off Eliot 
St.

Every now and again, the solids would need to be let go, too, but only when 
there was an offshore wind and an outgoing tide. But more than once the 
operators got it wrong and had to watch as a change of wind blew all the 
solids back to shore again, spreading it all along New Plymouth's beaches.

This issue came to a head in the late 1970s when New Plymouth residents 
formed what was known as the Clean Sea Action Group and began demanding 
introduction of full land-based treatment for the city's sewage. It became 
the biggest local body election issue in 1980, and new Mayor David Lean was 
swept into power on the strength of his support for the full treatment.

But then the council had to decide to actually go ahead with the project.

The plant was to use a new (to New Zealand) process called the extended 
aeration activated sludge process. Argument flew back and forth in the 
council's debating chamber, and in the end the decision to go the land-based 
way succeeded by a single vote, after one councillor changed his mind at the 
last minute.

New Plymouth's new Carrousel treatment plant, built in the Waiwhakaiho 
Valley, was commissioned in 1984 at a total cost of $18.2 million, and it 
was so leading-edge that its construction immediately triggered a New 
Zealand-wide re-examination of the appropriateness of discharging raw sewage 
out to sea.

The New Plymouth Waste Water Treatment Plant discharges (out to sea via an 
ocean outfall) water that's actually cleaner than the nearby Waiwhakaiho 
River, and all the solid waste is converted to fertiliser that is sold 
throughout New Zealand.

Called Taranaki Bioboost 630 (because it contains 6% nitrogen, 3% phosphorus 
and 0.5% potassium), it's proving a big hit and the 1300 tonnes a year that 
is produced is easily sold.

And while today the big liquefying chambers sit empty, the main sewers east 
and west, built of glazed earthenware, continue to be used.They remain in 
such good condition that the modern-day sewer lines have been able to be 
laid in them.

The two-decade old treatment plant continues to operate efficiently as well, 
to the extent that New Plymouth is now poised to enter a new phase of 
far-sighted development: piping all the district's sewage to the single 
plant. Inglewood's waste already goes there, thanks to the use of the former 
Moa-Nui effluent pipeline, which carries it to Manutahi Rd, where it 
connects via a newer line to the existing sewer that takes Bell Block's 
waste to the treatment plant.

And the New Plymouth District Council has now begun a $40 million project 
that, over the next couple of years, will see sewage from Oakura, Waitara, 
Onaero and Urenui go there as well.

Council general manager of community assets Anthony Wilson says the 
treatment plant is undergoing some upgrading work to handle all the extra 
flow, which will increase by around 5.3 million litres to a total of 25.3 
million litres a day.

"This will complete the vision that many people have had for many years. The 
only communities that won't be included will be Okato, Lepperton and Egmont 
Village.

"The good news is that, unlike many other communities and districts, New 
Plymouth has the facilities to be able to achieve this. That's important, 
because one thing is for sure, and that is that 24 hours a day, without 
fail, the sewage just keeps on coming

http://www.stuff.co.nz/stuff/dailynews/4339284a6551.html