Untreated Waste Water Discharges to the Sea

John Malcolm made this Official Information request to Whanganui District Council

The request was successful.

From: John Malcolm

Dear Wanganui District Council,

1. Since the failure of the current MWH/Council designed Waste Water Treatment plant in Whanganui, could you please provide figures for the volume of untreated sewerage and trade waste per annum that has been discharged through the Whanganui South Beach outfall.

2. If figures are available, what is the average mass of solids per cubic metre of untreated waste so discharged.

3. If figures are available, what is the mass of solids filtered from sewerage and trade waste annually, before discharge? How and where is this mass disposed of?

Yours faithfully,

John Malcolm
(Whanganui Ratepayer)

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From: John Malcolm

Dear Whanganui District Council,

I refer to my request for information of 24th September 2016. The Official Information Act requires a prompt response from you, and normally requires a response no later than 20 working days after the request was made. A response to the request has not been received by 21st October 2016.

Please make the requested information available without further delay. In the event that Whanganui District Council does not have the requested information, this should be indicated.

Yours faithfully,

John Malcolm

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From: Paul Drake
Whanganui District Council

Good Morning Mr Malcolm

 

In response to you information request received by this Council on Monday
26 September 2016.

 

 1. What is the volume of untreated sewerage and trade waste per annum
that has been discharged through the Whanganui South Beach outfall
since the failure of the Waste Water Treatment? 

Council started bypassing the WWTP on 1 February 2014. Council receives an
average of 11,000,000 m^3 of wastewater per annum. For the 2 years and 8
months that the WWTP has been bypassed the total volume of wastewater
pumped to sea is approximately 29,500,000 m^3.

 2. What is the average mass of solids per cubic metre of untreated waste
so discharged?

518 g/m^3 TSS

 3. What is the mass of solids filtered from sewerage and trade waste
annually, before discharge?

The TSS (total suspended solids or average mass of solids above) are
sampled after the wastewater passed through the screens. The 518 g/m^3 is
the load pumped to the ocean.

 4. How is the solids disposed of?

The solids removed by the screens is disposed of to landfill.

 5. Where is the solids disposed of?

The solids are disposed of at the Bony Glenn landfill site.

 

 

Regards

 

Paul Drake

Paul Drake | Legal Officer
P: +64 06 349 0001 | M: +64 027 212 0633
[1]www.whanganui.govt.nz
Whanganui District Council | 101 Guyton Street | PO Box 637 | Whanganui
4500
[2]Whanganui District Council

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From: John Malcolm

Dear Paul Drake,

Thank you for your timely response to my request for information. Most of my questions were answered.

However, Question 3 asks what annual mass of solids is removed by the filtering process BEFORE the remainder is discharged to the sea. The figure quoted is that provided in answer to Question 2. ie. 518g/cuM as the total suspended solids AFTER filtering.

What I am seeking in this question is the annual mass of filtered solid materials disposed by other means, and therefore NOT discharged to the sea.

Many thanks

Yours sincerely,

John Malcolm

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Luke left an annotation ()

While one waits for an answer to question 3, the information provided to-date shows that nearly all the water that bypassed the WWTP was untreated sewage (29,328,000 m^3). On face value this means that for the last 2 years and 8 months, virtually all sewerage and trade waste has been ejected through the outfall.

The total tonnage of untreated sewage(15,281) is very heavy. However, I also wonder what is the volume of these solids (i.e. if the solids were to form a cohesive whole, what is the space/volume that this would occupy). This would help to understand the footprint on the sea.

Just a note on the difference of "sewage" and "sewerage". "Sewage" is waste from all sinks, toilets, laundries, kitchens and bathrooms. This waste flows through a "sewerage" network of underground pipes and pumping stations to a treatment plant.

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John Malcolm left an annotation ()

Thanks Luke,

I always did have a problem with "sewage" and "sewerage" but confess I hadn't given it too much thought to correct my sloppy language.

15,200 metric tonnes of solids over 2.3 years is a significant environmental load, some of which will not be organic. I doubt we have a Minimata on our doorstep (at the moment) but further questions do need to be asked about the composition of the discharges to the sea and to landfill.

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From: Paul Drake
Whanganui District Council

Good Morning John

Infrastructure respond:
Council does not weigh the rags and other items removed from the incoming wastewater stream by our 3 mm screens. We do not have an answer for question 3.

Regards

Paul

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From: John Malcolm

Dear Paul Drake,

Many thanks

Yours sincerely,

John Malcolm

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