New Napier sewage plant … why bother?

The Napier City Council proposes to spend $30 million on a ‘sewage treatment’ plant that — like its Hastings cousin, which must seek consent approval in 2013 — purports to ‘transform’ poop into ‘bacterial mass’ that will still be dumped into the Bay.

I say: Why bother? And so I’ve submitted against the NCC consent application.

The only concern ostensibly addressed here is that Maori object (like anyone might) to dumping poop directly into the sea. So both Hastings and Napier Councils have striven mightily — and so far successfully — to convince Maori leaders that the process used by so-called ‘biological trickling filters’ (BTF) — together with passing the effluent over ‘sacred rocks’ — transforms sewage into some other substance that’s OK to dump into the sea.

The NCC’s application materials assert that “the current discharge, i.e. milliscreen treatment only, is having a minimal effect on the  receiving environment. Notwithstanding that statement, NCC proposes treating the wastewater to meet the cultural and social expectations of its citizens.”

So, the $30 million goal here isn’t really to clean-up the effluent; it’s to ‘transform’ it — a concept that’s spiritual, not scientific. In fact, Napier Council’s “proposal for determining spiritual and cultural concerns via scientific means” has alarmed the HDC staff, according to views to be put before the Hastings Council this week.

As the Napier application puts it:

“In general, there is some reduction of suspended solids across the pilot plant, with a reasonably consistent effluent solids concentration, but a longer period of stable operation is required before any long-lasting conclusions can be reached about the overall removal of influent TSS through the process. However, as transformation of the waste is the principal aim of the BTF plant, absolute reduction of suspended solids is not as important as a change in the nature of the solids between influent and effluent.”

In fact, the Napier application proposes no specific limits on harmful nutrient and other discharges into the sea (such as suspended solids, oil & grease, BOD, faecal coliforms).

That’s the ‘clean-up’ Napier (and Hastings) ratepayers are expected to pay millions for.

Yes, it’s true that BTF’s cause a physical/chemical alteration of the ‘influent’. It’s changed into a gel-like substance that’s flushed out of the filters in blobs and into the sea.

Says the Napier consent application: “The overall BOD5 and solids load to the environment will be reduced, although it is difficult to quantify by exactly how much, due to the fact that a feature of the process is that biological solids, that themselves constitute some BOD5, will be purposefully discharged to the ocean … These solids are not considered offensive, and are passed to the ocean for final treatment as part of the natural cleansing process.”

In other words, the sea will take care of our waste, as it always has.

But the fact is, no one knows how this substance behaves once it’s in the sea, including where it will go. Its characteristics are different than the screened-only (and finer particle) sewage that Napier now pumps directly into the Bay. Moreover, the ‘bacterial mass’ is just that — a gel that when it ultimately dissolves will re-release both bacteria (“new life forms” as the Napier application terms them), nutrients and heavy metals into the water.

No one has bothered to study this process — even though NCC has been asked for such information by HBRC — and what ecological risks the biomass itself might entail.

Elsewhere in New Zealand, where BTF treatment is used, the effuent is channeled into clarifier tanks where the bacterial mass (the solids) is settled out and hauled away as sludge, leaving only a cleaner effluent to be discharged (which can include dispersal onto land, as is planned for Central Hawke’s Bay’s sewage treatment).

Napier ratepayers might as well face reality. What this plan comes down to is that you’re looking at paying $30 million not to actually clean-up your mess and lessen your impact on the Bay, but to appease a Maori cultural concern.

I’m not in any way opposed to addressing that concern. However, let’s be honest about what’s going on with this particular half-baked ‘solution’. From a purely ecological standpoint, the waters of the Bay might be just as well or better off with the status quo. But the status quo is no longer acceptable.

A far better solution, if NCC is stuck on the BTF approach, would be to add the clarifier stage that other BTF systems employ. Then Napier — and Hastings, if it followed suit — would really be doing something for the environment, instead of pretending they are.

Tom Belford

P.S. Here is my submission to the Regional Council.