Trade waste charges

Trade waste is considered any liquid discharged to the sewer system by a business. Council requires all liquid waste to be disposed in an approved way and controls the quantity and composition of trade waste discharges to the sewer system. We charge industries as an incentive to reduce their flows and loadings.

All discharges from commercial sites must comply with the Wastewater Bylaw 2014 (1.4MB PDF), which places restrictions on discharge rates and strength of the effluent. Some discharges require a consent. For enquiries regarding trade waste consents please phone Council on +64 3 546 0200 and ask for the Trade Waste Officer.

Charges

Trade Waste charges are based on the total costs recovered by the Council for conveyance, treatment, and disposal of the effluent regardless of which treatment system serves the premises.

There are two methods for how charges are decided:

Method A - The Quality-Quantity Approach

The estimated total cost for the current financial year to be recovered by the Council through the Drainage Account for receiving, conveying, treating and disposing of wastewater within its district.

This cost is proportioned to the various stages of the service provided as follows:

Conveying
Capital charges and operating costs of sewers and pumping stations are allocated with respect to the rate of discharge. From 1 July 2017, the charge for Method A Conveying is $606.11(GST inclusive) per litre per minute.

Treatment
Capital charges and operating costs for wastewater treatment and disposal are allocated with respect to Biochemical Oxygen Demand ('BOD') 5 loadings. From 1 July 2017, the charge for Method A Treatment is $1,097.29 incl. GST per kg BOD per day. The charges in respect of special wastes are based upon the rate of discharge; and BOD 5 as hereinafter more fully dealt with and the charges for excess volume shall be based upon the first of these only, viz rate of discharge (except where hereinafter expressly provided).

The methods to be used for determining the rate of discharge and BOD 5 shall be as

Rate of Discharge
The rate of discharge from any trade premises shall be deemed to be the average rate (in litres per minute) at which discharge is made over eight periods each of twenty-four consecutive hours duration, which are reasonably representative of peak conditions during each financial year or over such lesser numbers of periods as may be agreed between the Council and the discharger.

Biochemical Oxygen Demand
The amount of BOD 5 for which any trade premises is chargeable shall be calculated in accordance with the results of analysis of samples collected by the Council proportionally to flow over periods of 24 consecutive hours on eight occasions that are reasonably representative of peak conditions during each financial year or on such lesser number of occasions as may be agreed between the Council and the discharger. The analysis shall be carried out on a shaken proportionate sample, which shall be analysed by the standard five day BOD 5 test.

The charges payable to the Council by owners of trade premises in respect of the receiving, treatment and disposal of trade wastes discharges from their respective trade premises shall, subject to the other provisions of this bylaw be calculated in accordance with the following basis:

Conveying based on rate of discharge per litre per minute. Treatment based on BOD 5 per kilogram BOD per day.

A wastewater charge is set under Section 16 of the Local Government (Rating) Act 2002 to recover the costs required for Council's sewerage disposal system. This charge is levied to all units to which the Council's sewerage disposal service is provided. The commercial wastewater charge from 1 July 2017 is $103.48 (GST inclusive).

The total amounts calculated under Clause 4 above shall be reduced by deducting the wastewater charge under Clause 5 above.

This final charge is expressed D = (P 1 O + P 3 R) - E

D Total annual charge
P 1 Cost of treatment in $/annum/kg BOD/day
P 3 Cost of conveying the volume received in $/annum/litre/min
O BOD as determined in clause 4 hereof in kg per day units
R Rate of discharge from the trade premises in litres/min as determined in Clause 4 hereof
E Wastewater charge, see clause 5 above

In calculating such charge in accordance with clauses 3 to 6 inclusive hereof, any domestic sewage, which is discharged from the premises affected shall be deemed to be trade wastes. Please note that the application of this formula does not entitle an owner to a rebate.

Should final information with regard to rate of discharge or BOD 5 not be available in respect of any period for which payment becomes due, the Council may assess a provisional charge which shall be payable as if it were the proper charge, provided that as soon as the proper charge can be calculated by the Council, notice shall be sent to the owner and any refund or additional payment as the case may be shall be made within one calendar month from the date of dispatch of such notice.

Method B - The Quantity Approach

For trade premises, where the Council considers that the trade waste charge is likely to be less than twice the cost of monitoring, testing and calculating the charges using Method A, and for hotels, motels and camping grounds, the trade waste charge shall be calculated D 1 = (W x F x C) - E

D 1 Quarterly charge
W Volume of water supplied to the premises during the period.
F Correlation factor between water usage and sewage flows and shall be 0.8 unless another figure is agreed between the Council and the particular premises.
C The cost per cubic metre to the Council for conveying and treating the City's sewage. This figure shall be set annually by the Council and shall be based on the estimated total cost to Council for conveying and treating waste water within its district and the previous year's flow, expressed in $/m3 .
C As set each year in the LTCCP; from 1 July 2017 the Method B Combined charge is $1.87 (GST inclusive) per m3.
E The commercial wastewater charge.