With this post (also the lead article in the March BayBuzz Digest), we welcome a new reporter, Kathy Webb, a journalist with a great reputation in Hawke’s Bay, most recently writing for the Dominion Post.

Kathy will investigate a variety of regional issues in-depth for BayBuzz in the coming months. In her lead-off story, Stinkin’ Pipes, Kathy examines problems surrounding the new Hastings wastewater treatment plant in Clive. Not exactly a glamour assignment! But with $27 million invested, and more required as the Hastings Council struggles to resolve odour problems, we felt the situation warranted a closer sniff.

[Part 1 follows below; Part 2 follows tomorrow. Or download the entire article here.]

Stinkin’ Pipes!
By Kathy Webb

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.”

Two perspectives
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.

Odour management
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.

Tomorrow, Part 2: $27 million down the toilet?

[Or download the entire article here.]

Join the Conversation


  1. Um … perhaps not just a bad smell … and endeavouring to de-odourise pehaps the most toxic of natural gases?

    I would have thought that hydrogen sulfide (H2S or sewer gas) was of prime concern with respect to any sewage treatment system … so it is somewhat surprising to find that post installation contingencies are required at all. It really indicates that someone did not do their homework sufficiently.

    So, all in all, an interesting article. Also of interest is that the Regional Council will not release their monitoring data, but it would appear, were prepared to attribute the 'odour' / toxic gas to different sources … organic orchards and lime sulfur use?

    The placement of the monitor is such that it will only measure H2S from the northeast form the sewage works, so it is well placed in regards to apportioning source in respect to this gas … wind direction, rain or fine, and presumably will also have recorded sulfur dioxide, nitrous oxide and PM2.5 particulate matter.

    That it was stated that the H2S measured (presumably from July to the time of this report) ranged from 4 to 7 parts per million (ppm) strongly indicates that the ambient H2S levels were at minimum greater than 4ppm – not ppb (billion) as one would expect from background levels in an area without geothermal activity. This is of real concern and is something that urgently needs addressing.

    That the Regional Council forced the closure of the plant suggests that it was not only in breach of odour standards, but also health standards.

    Will Arnott's missive on lids and a resource consent for discharging an odour resolve this issue? Or is this equivalently naive? It is, not just a bad smell, it is a toxic gas.

    To emphasise this point, and that the requisite information has been available for a long time:

    The Illinois Institute For Environmental Quality reported its findings on Hydrogen Sulfide Health Effects and Recommended Air Quality Standards in 1974. The Illinois Institute summarized the literature on human health effects and their observations on the health effects in Illinois ambient air concentrations. In general the following was reported:

    Concentration of H2S Symptoms:

    O.12 mg/m3 (0.08 ppm) – Increased mental depression, dizziness and blurred vision.

    0.45 mg/m3 (0.32 ppm) – Increased incidence of nausea, loss of sleep, shortness of breath, and headaches

    1.0-10 mg/m3 (0.7-6.7 ppm) – Increased incidence of decreased corneal reflex (convergence and divergence)

    10-70 mg/m3 (6.7-47 ppm) – Irritation of conjunctiva, fatigue, loss of appetite, insomnia.

    The Illinois Institute recommended a standard for gaseous hydrogen sulfide of 0.015 mg/m3 (0.01 ppm) to minimize adverse health effects from chronic exposure in urban air.

    Kilburn KH and Warshaw RH. Hydrogen sulfide and reduced-sulfur gases adversely affect neurophysiological functions. Toxicology and Industrial Health, Vol 11, pp. 185-19, 1995.

    Kilburn KH, MD. (2004) Endangered Brains. Princeton Scientific Pulications Co. Inc., Birmingham, Alabama. ISBN : 0-9745460-0-3. pp. 77-85.

    Ex-workers and neighboring residents (total of 35 individuals) were compared to 33 unexposed controls. The ex-workers and residents were exposed to hydrogen sulfide and other reduced-sulfur compounds emitted from a refinery. The concentrations of hydrogen sulfide and other reduced-sulfur compounds were monitored at ground level. Depending upon the day and year hydrogen sulfide concentrations ranged from a low of 10 ppb to 8.8 ppm. Reduced sulfur compounds (dimethylsulfide, mercarptans, carbon oxide sulfide) ranged from 2 ppb to 71 ppm.

    Symptoms involving the respiratory tract (chest tightness, palpitations, chest pain, dry cough, cough with blood, dryness (mouth, nose, throat,), throat irritation, eye irritation, reduced sense of smell were greater in the exposed than the controls.

    Neurological symptoms were also elevated over the controls. These included: dizziness, lightheadedness, loss of balance, lack of concentration, recent and long-term memory loss, mood unstableness, irritability, exhilartion.

    Sleep disturbances were also noted in the exposed, which were: cannot fall asleep, wake frequently, sleep few hours, somnolence.

    Skin symptoms were itching, dryness and redness.

    General Symptoms were: headache, nausea, libido decrease, excess fatigue, indigestion, loss of appetite, lack of tolerance to alcohol.

    Neurophysiological deficits were found in the exposed group: simple reaction time was increased; sway speed was faster, color discrimination was reduced and psychomotor speed was time was increased.

    The neurological injury is accumulative. That is each exposure results in increased brain damage. The damage individual does not recover, and brain dysfunction continues for years. These observations are supported by research on animals, where it has been shown that accumulative exposures adversely affect cytochrome oxidase enzyme activity and changes in the hippocamal EEG

    Profile Mood States (POMS) also showed abnormalities when compared to controls. There were increased scores for anger, depression, tension, confusion, fatigue and vigor.

    The automatic (subconscious) parts of the neuro-axis were impaired. Impaired performance was accompanied by reduced perceptual motor speed.

    The exposure to reduced-sulfur gases, predominantly hydrogen sulfide, was considered the most plausible explanation of the neurotoxic effects in this study.

    Gaitonde UB, Sellar RH and O'Hare AE. Long-term exposure to hydrogen sulphide producing subacute encephalopathy in a child. British Medical Journal. Vol 294, pp. 614, 1989.

    This is a report on a 20-month old infant exposed for a year to 0.6 ppm hydrogen sulfide downwind from a burning tip gas ignition point for a colliery. The child had subacute necrotizing encephalopathy in the basal ganglia and white matter.

    Chronic Reference Dose (RfD) Based upon animal studies and the child reported by Gaitonde et al, the U.S.E.P.A. has recommended a RfD of 0.8 micrograms per cubic meter of air for both subchronic and chronic human inhalation exposure. The RfD is that concentration at which no adverse health effects should occur. Concentrations above the RfD may result in adverse health effects, including neurotoxicity.

    Conclusion: Chronic and subchronic exposure to low concentrations of hydrogen sulfide and other organosulfur compounds (reduced sulfur compounds) do cause long-term health problems in humans. These problems appear as various symptoms of the upper and lower respiratory tract, central nervous system, skin and eyes. The central nervous system symptoms are associated with permanent neurophysiologcal deficits. Injury to the central nervous system includes damage to the basal ganglia and white matter

    0.02 ppm – No odor

    0.13 ppm – Minimal perceptible odor

    0.77 ppm – Faint, but readily detectable odor

    4.6 ppm – Easily detectable odor, moderate odor

    27.0 ppm – Strong, unpleasant odor, but not intolerable

    The Hawkes Bay has the worst health statistics of any region in New Zealand … is it any wonder why?

    Are our Regional Council doing enough in regards to our air quality? The sewage works issue is simply another example of what activities are being permitted without sufficient safe guards, with an almost cavalier disregard for public health.

    Where are our Medical Officers of Health in respect to this and allied issues … we know they all use the toilet, but are they really all orchardists?

    Hydrogen sulfide, sewer gas, H2S is a toxic gas with an odour of rotten eggs … it is not just a 'bad smell.' The two primary sources in the Hawkes Bay are the sewage works and the use of lime sulfur by organic orchardists.

  2. Thats a really helpful contribution Simon- NOT.

    This plant [ well a third of a plant] was never going work even before it was built. The whole thing, if it had not cost close to $30 million, is a joke. Lets hope Napier learns from their mistakes, Gisborne has.

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