Are consent conditions for wastewater discharge becoming too prescriptive? Are they locking the applicant into
a specific solution at an early stage and not enabling design development? Can
there and should there be a middle ground? I think so. Let me illustrate with the following story...
Williamson District Council (WDC)
is planning to install a wastewater treatment plant, which will discharge
treated effluent to the Taylor River. WDC
has undertaken all necessary ecological studies and options assessments to
satisfy the McCullum Regional Council (MRC) that the impact of the wastewater
discharge on the Taylor River will be less than minor. An application for a discharge consent is
Following the application there
is much ‘to and fro’ between MRC and WDC around the information provided in the
As a result, MRC proposes a set
of conditions that WDC must comply with.
WDC is slightly surprised with their prescriptive nature. The following dialogues occur:
why have you proposed a condition that we install a membrane bioreactor (MBR)
MRC – To
ensure that your discharge will meet the
effluent quality required and that’s what you proposed in the application
but, the RMA is an ‘effects based’ legislation; therefore as long as the
effects of the discharge are less than minor, it shouldn’t matter what
technology we provide. We only presented an MBR as an example of how the
proposed conditions can be met.
But we need surety that your discharge does not cause adverse effects and we
can ensure this by specifying the conditions, including technology, which, by
the way, was part of your options study.
WDC – we
agree that MBR was part of our options study and it may be the solution;
however we wish to have the flexibility to go to with any technology which
provides us the best practical and economical solution.
I can understand both perspectives.
It’s MRC’s role to regulate the RMA.
And the WDC want to achieve the RMA outcome by minimising the burden on
Some consent conditions do
specify the technology. But, I believe
that once the effluent quality targets have been agreed, the process technology should be left to the
local council, the applicant. To satisfy
the regional councils, which require an assurance that the applicant will
provide the appropriate technology, I think that local councils should state
the various technological options, but refrain from stating a preferred
technology. This gives them the choice of selecting the best option at the
time. In some cases, due to a prolonged
consenting process, there might be better and cheaper options available at the
time of implementation. Also, through
design development, new ideas (potentially better) and options emerge as the
Such an approach would give WDC the flexibility it requires, and
also give MRC assurance that appropriate technology will be implemented.
In other words, MRC should
specify the consent conditions and let WDC decide on how they will satisfy
those conditions. After all, it is an
‘effects based’ assessment.
Back to our story with a happy
MRC – ok, what nutrient removal
processes will you be evaluating?
WDC - It could be SBR, MLE, Bardenpho or MBR. All well proven technologies.
MRC – ok, we will amend the
condition as follows:
The applicant shall install a
biological nutrient removal plant to satisfy the effluent quality conditions
specified under Clause 12.
This thought leadership article is by Ash Deshpande, a Lead Process Engineer at Harrison Grierson.
Back to HG Perspective