A monumental waste of money, or a marvel of science and cultural sensitivity? The jury is still out, but one thing is sure: Almost since the day it was switched on nine months ago, Hastings ’ new $27 million sewage system has produced a seriously nauseating smell it wasn’t supposed to.
Some days it’s so bad John Robertson loses his breakfast as soon as he steps out the front door. The stink from Hastings ’ new $27 million biological trickle filter sewage tanks at East Clive “has to be smelled to be believed,” he says. “It gets right down into the back of your stomach.”
One of his neighbours says she tries not to breathe too deeply when there’s a fresh northeasterly blowing across the top of the plant’s two giant bio-trickle filter tanks. She describes a raw-sewage taste in her mouth, and cleans her teeth often.
Other neighbours suffer when the wind is more southerly.
There’s also another aspect of this much-hailed technology that has raised eyebrows among those less directly affected by its olfactory misfortunes. The inclusion of spiritual cleansing in a modern engineering process was acknowledgement of Maori cultural concerns, but some — Maori and Pakeha — wonder about the place of that in a publicly-funded sewage treatment plant.
Complaints about an awful smell began pouring in last July, shortly after the Hastings District Council switched on the much-heralded new bio-trickle treatment plant, which won the top national prize in the Technology Innovations category of the 2006 NZ Post Management Excellence awards.
Since then, it’s been a nine-month headache for everyone in charge of it or living with it. Every time the plant builds up toward optimum performance, a gut-wrenching stink wafts across East Clive and the tanks have to be switched off. As Hastings Council chief executive Ross McLeod puts it, “there hasn’t been any substantial, protracted operation of the plant yet.”
There are two perspectives on the smell problem.
The Council insists the bio-trickle filter (BTF) tanks are performing exactly as intended, doing a demonstrably good job, and that the source of the smell is farther back up the line, in the actual sewage coming from Hastings.
To the residents of East Clive, that’s a fine distinction. They don’t particularly care which part of the system the smell is coming from. They just want fresh air, which they generally had until the Council got technologically adventurous with $27 million.
Everyone at the Council that Baybuzz spoke to is confident the odour can be conquered, and the bio-trickle system will prove itself a huge asset.
Wastewater manager Brett Chapman explains that the contents of the separate domestic sewage line from Hastings are traveling a little slowly — six to eight hours — from Hastings to East Clive. That gives sulphate-eating bacteria an ideal opportunity to create hydrogen sulphide gas, which forms between 4 and 7 parts per million in the waste. That’s more than adequate to create a stink when the gas is released into the air as the waste is disturbed by being pumped to the top of the filter tanks.
The sewage is also unexpectedly acidic. “The pH in our waste stream is lower than desirable. We are testing right up the line, right back, to see why, to work it out,” Mr McLeod says. He doesn’t discount an illegal discharge into the pipeline. “Is there an improper waste stream from somewhere? Is there somebody contaminating the system? We want to find out,” he says.
Back at East Clive, Mr Robertson, who has a degree in engineering, says it was clear from the outset there was hydrogen sulphide coming off the filter tanks, but for months the Council kept telling residents there was no unduly bad smell. Or there was a smell, but it was coming from elsewhere. Or it would disappear when the plant had been operating for just a little longer.
Mr Robertson and his partner Rachel have put nearly $1 million into their accommodation business, Driftwood Cottages, across the road from the filter tanks.
They bought the bare land in 2004, before the filter tanks existed, and began building later that year. Mr Robertson said no one at the Council was able to tell him at that stage what sort of sewage system might finally be built, but he expected nothing worse than the relatively inoffensive old milliscreening plant.
The truncated bio-trickle system that eventually materialised has been a nine-month nightmare, he says, and somewhat ironically, has cost his environmentally-friendly, four-star business a lot of cashflow. For three months late last year they took no bookings because they knew guests could not tolerate the foul odour enveloping their cottages.
One of the first things the Hastings Council did when it began investigating the stink was to install a low-tech “odour management system” consisting of plastic hosepipe strung around the treatment plant’s perimeter, to dispense air freshener into the coastal breezes swirling around East Clive. That didn’t work, so last month more air freshener hoses were strung around the tops of the filter tanks, while investigations and tests continue.
The smell came as a great surprise to all involved in the bio-trickle plant’s design and construction. A small-scale trial plant had worked well, producing no odours and no problems.
In fact it worked so well the Hastings Council assured the Regional Council there would be no odour from a full-scale bio-trickle system. On that basis, the Regional Council allowed an open discharge channel, did not include any regulations regarding odour control in the resource consents, and did not require the District Council to get a permit to discharge offensive odours to the air.
However, there was a flaw in the process. The test-plant trials were done with a much bulkier and faster-moving sewage load from both domestic and trade sources, and the results were extrapolated to form models for the design of a domestic-only treatment plant.
History has shown it wasn’t that simple.
Trade waste consists largely of water from food processing industries, and makes up about 70 per cent of Hastings’ effluent. That waste is all still going through a pipeline to the old milliscreening plant at East Clive, where it is pushed through a 1mm grid, and then pumped directly into the Bay.
Without that bulk of water, the remaining domestic waste stream, which still includes discharges from a few trade sources with special consents, has turned out to be too light a load to keep a steady flow through its own separate pipeline to the new bio-trickle plant.
Mayor Lawrence Yule says the fundamental mistake was that the pilot plant trials were done with a much bulkier waste stream. “Now the volumes have dropped and there’s not as much movement down the pipe as we envisaged.”
The smell was completely unexpected, he says, but he remains 100 per cent confident it can be conquered and the BTF plant will be able to demonstrate how effective it really is. “The system is making a massive difference to the quality of the water going into Hawke’s Bay. Any inference that it isn’t is clearly untrue and incorrect.”
He’s also comfortable with the Council’s decision to build stand-alone filter tanks without lids, and without the primary and tertiary treatments that normally sit alongside bio-trickle filtering tanks.
The Hastings Council declines to say how many calls of complaint it has received about the smell, but the HB Regional Council has logged 56, and is now responding to every call from East Clive. It shuts down the filter tanks and diverts the domestic waste to the milliscreening plant when the smell gets too bad.
It has also served an abatement notice on the District Council. Despite a lack of resource consent conditions, the odour emanating from the new plant is illegal under the Resource Management Act. The District Council has until May 17 to eliminate the odour or install lids costing $2m-$3m on the tanks by August 17. Compliance manager Bryce Lawrence says HBRC has also told the District Council to apply for a permit to discharge odours to the air.
Council wastewater manager Brett Chapman said odour from the new plant was always a possibility, “but we didn’t expect there would be. Now that problem exists and it has created a problem away from the plant itself.”
He hopes the lids will not be necessary because “they would contain the odour but not actually deal with it.”
Another source of odour has been the Paptuanuku Channel. In a letter to the Regional Council last October, Mr Chapman said the stop-start operation of the filter tanks had required extra flushing to remove “undesirable biomass.”
“A by-product of the increased flushing is increased odour generation downstream of the BTFs as the biomass passes through the open-air Papatuanuku Channel … The problems of reduced biomass and frequent flushing have resulted in periods of increased odour generation which has impacted on the neighbouring community,” he wrote.
In the meantime, the Hastings Council continues experiments with a range of options to eliminate the smell, including flushing the pipeline daily, pouring in 600kg of magnesium oxide a day (at a cost of $1000 per day) for a week to raise the pH level of the sewage and deal to the sulphate-eating bugs. If that became the preferred solution, the cost would have to be added to the plant’s $600,000 annual operations budget.
The next trial will use a secret mix of superbugs bought from a private company.
$27m down the toilet?
Environmental watchdog David Renouf says Hastings has effectively thrown $27m down the toilet. Bio-trickle filtering without a first-stage settling process and a third stage clarifier to remove all the filtered sludge is a waste of money, he says, because large amounts of the biomass that removes nutrients from the raw sewage are flushed out of the tanks along with the filtered liquid, on to the seabed.
“It’s a bit like vacuuming your lounge, then emptying the bag all over the floor,” he says. He believes the bio-trickle plant and its accompanying “Papatuanuku Channel” were the $27m price tag for Maori agreement to a sewage-disposal solution for Hastings.
But he says Maori were misled into believing there is no human waste in the filtered discharge to sea, because although it might not be raw anymore, it is part of a chunky glutinous mass that will take a lot longer to disperse than milliscreened sewage. It’s unknown what effects biomass will have on the marine environment, because not enough tests have been done yet to prove it is harmless. And it still contains heavy metals, viruses, parasites and suspended solids that the filters have not dealt with.
Mr McLeod rejects any notion of “a $27m spend just to satisfy cultural concerns,” and says the project was necessary to meet conditions for the plant’s resource consent. The Council’s tangata whenua wastewater committee has yet to sign off on the new bio-trickle plant, but if it refuses to do so, “we’ll have to work through the whys and wherefores.”
Group asset manager David Fraser says the concept of changing the form of human waste into biomass came from Monty Paku, one of the wastewater committee members, and he’s confident the system will get the final seal of approval.
The Papatuanuku channel is an open drain studded with rocks that were blessed by Maori and are now generally referred to as “sacred,” although the Council itself does not use that word. The rocks were brought from a quarry at Linton, near Palmerston North, to spiritually cleanse the filtered discharge before it heads out to sea. It is “more symbolic than anything,” Mr Fraser says. But it is a “standard concept across New Zealand , with slightly different perceptions between iwi.”
He rejects Mr Renouf’s criticism. The filter tanks can be compared to a “quick composting” bin in a garden, turning waste into another form, but much more quickly.
“What’s coming out is bugs’ waste.” he says, and the Council is monitoring the seabed around the sewage outfall 2.5km out at sea “to see if there are any adverse changes.”
So far, the Regional Council has not replied to BayBuzz requests to see the monitoring data.
In a magazine article headlined “Cultural dreams become a technical reality with innovative wastewater treatment,” Mr Fraser describes the new Hastings system as “a model that others can follow.” “Essentially, we have secondary treatment for half the cost of primary, or one third the cost of the traditional configuration for biological trickling filters.”
The Maori cultural element focused on avoiding the transport of sewage sludge on roads past homes, marae, etc, and required “a great deal of lateral thinking and discussion from within the Maori community,” which eventually aligned the bio-trickle process with “the long drop approach, in which human waste was allowed to grow old and become inert with dignity.”
The Council’s legal adviser, Mark von Dadelszen, is more effusive. In a written article he describes the consultation and co-operation that led to the construction of Hastings’ novel take on bio-trickle filtering as an historic blend of Maori spirituality and modern science.
The Papatuanuku channel was the solution, he said, by invoking the sons of Papatuanuku ( Maori God of the Earth) to purify and spiritually cleanse the sewage, with “Tanemahuta providing biomass to transform kupara (faeces) by removing the mauri (spirit) of human wastes. Tangaroa (the sea) receives the transformed waste after passage through Papatuanuku and heals himself through movement of the ocean, and Tawhirimatea (god of the winds and weather) agitates the surface of Tangaroa and through a synthesis of air and water completes the cleansing process.”
Des Ratima, a member of the District Council’s Maori Joint Committee, is less than impressed by the lateral thinking and consultation that led to the construction of a waste disposal channel named Papatuanuku.
In fact, he’s horrified. “It’s not respectful at all. It’s totally inappropriate, almost to the point of being offensive.” Papatuanuku (Mother Earth) is a concept of support and nourishment resulting in a cleansing, “not to take dirty water and make it less dirty,” Mr Ratima says.
He’s surprised the Tangata Whenua Committee allowed what he considers to be a serious spiritual distortion, and intends to consult “a few people whose opinions I respect, and see what they think about it.” A name change for the channel could well be on the cards, he says.
The East Clive treatment plant has already attracted a lot of attention from other councils.
Napier is poised to build an identical system at Awatoto, but its tanks will have lids. Mayor Barbara Arnott says Napier is still watching events at East Clive before seeking its own resource consents later this year. “Everyone’s learned a lot from the Hastings experience.”
Napier should not have the same problems because it has a larger urban area and therefore higher volumes of domestic sewage to maintain momentum in the pipeline and filtering, she says.
It will also have a permit to discharge offensive odours to the air!
Sidebar: “A saga of investigation and consultation”
In the early 1980s, Hastings was pumping all its sewage out to sea via a 2.75km pipeline, the longest ocean outfall in the country. It was a minimalist approach, relying on oxygen-rich receiving waters and high sunshine hours to provide plenty of ultra-violet light to break down and disperse the sewage.
Milliscreens were added in 1993 to catch the toiletries and other items that sometimes got through the initial screening.
In 1998, the Hastings Council sought a renewal of its resource consent to continue the discharge. Maori objected to a continuation of human waste going straight into the ocean, and eventually the Council was ordered to heed their concerns and consult them.
In 2001, the Council was granted consent to build a new wastewater treatment plant, to be ready by 2007, and the Council-Maori Tangata Whenua Joint Wastewater Committee was formed with the task of ensuring any new system resulted in “the significant removal of kuparu (human waste)” by 2007, and the “complete removal of kuparu” by 2009.
Maori were not happy about the natural settlement system being considered by the Council, so the committee set about finding an alternative to meet everyone’s standards. The stand-alone bio-trickle filter tanks were the result.
Hastings’ resource consent expires in just four years, so the Council must begin a whole new round of public consultation later this year. Mr Chapman says public expectations for sewage treatment have raised the bar a lot in recent years, so he will not be surprised if there turns out to be a mood for even more treatment, maybe sludge removal after filtering, or ultra-violet light.
Sidebar: “How it Works”
A traditional bio-trickle filter system has three stages – primary treatment such as settling tanks, followed by the trickle filtering, then clarifiers to collect the resulting sludge, which is removed before the wastewater flows on to its intended destination.
Settled sewage is pumped up to the top of each tank, where rotating arms spray it on to some form of media on which sewage-eating microbes, composed of algae, fungi, protozoa, rotifera, nematodes, and aerobic bacteria, live as a slimy substance commonly called biomass. As the wastewater trickles through the media, the microbes in the biomass grab and eat the nutrients in the sewage.
But Hastings does not have a traditional bio-trickle system. Mr Fraser says that is because traditional systems, built when milliscreening was unavailable, went out of vogue as more cost-effective ones were developed. To save money, it dispensed with the usual first and third stages, and built only the second-stage filter tanks. It also omitted lids on the filter tanks and a closed channel to the sea outfall, which it replaced with an open “spiritual cleansing” channel studded with “sacred” rocks from a quarry at Linton, near Palmerston North. The rocks were free, but cost $5000 to truck to Hastings.
Raw domestic sewage arriving at East Clive is screened and pressed to remove the bulkiest of solids, which are then carted off to Omarunui landfill.
The rest is pumped to spray arms at the top of two 37 metre diameter tanks, each containing five million pieces of plastic, nine metres deep. The wastewater takes 12 minutes to trickle down through the plastic.
It’s a complex process. Bio-trickle filters need a critical mass of sewage to keep their biomass alive. Too much or not enough biomass creates odour. Blockages in the media can cause sections to go anaerobic and smelly, so every few hours, the tanks are flushed to remove any lodged solids such as toilet tissue and excess biomass.
The filtered wastewater and flushed-off biomass flow into the Papatuanuku Channel for “spiritual cleansing” before entering a pipeline where it is joined by all the milliscreened trade waste from Hastings , and pumped 2.5km out to sea.