Question:
Hello,

Thank you for providing the RFT

We note that the current documentation refers to:

“Throughput: Suitable for Narrung STP sludge production (tenderers to confirm sizing basis)”

“Duty: Intermittent operation aligned with sludge production cycles”

However, no specific data is provided to define these requirements.

To proceed with equipment sizing and ensure a compliant design, could you please clarify:

- required throughput / processing capacity (average and peak)

- expected operating regime (hours per day / duty cycles)

- sludge characteristics, including pH, TSS/VSS, abrasiveness, and presence of grit/sand

- installation conditions (indoor or outdoor)

In addition, as SCADA integration is required, could you please provide details of the existing control system, including:

- PLC/SCADA platform currently in use

- communication protocols

- current centrifuge control configuration (if available)

Providing this information will allow us to minimise integration scope and align the proposed equipment with your existing system as closely as possible.

At this stage, these details are required to ensure the equipment selection and sizing are appropriate.

Answered on 07/Apr/2026 09:48 AM:


Throughput / Capacity

The dewatering system shall be designed to process sludge at a nominal hydraulic throughput of approximately 40–55 m³/hr at ~1.4% w/v solids concentration, equating to approximately 400–420 kg DS/hr.

The system shall be capable of accommodating peak hydraulic flows of up to 20 L/s (˜72 m³/hr) for lower concentration sludge conditions

Operating Regime

The dewatering system is expected to operate on an intermittent basis aligned with sludge production, with a nominal runtime of approximately 60 hours per week. Operation may occur in extended continuous runs (e.g. up to 10–12 hours per day) depending on sludge inventory and operational requirements

Sludge Characteristics

• Sludge Type: Predominantly waste activated sludge from SBR systems and aerobic digesters

• Solids Concentration: Typically, 1.2–1.6% w/v, with variability depending on process conditions

• pH: Typically, 6.5–7.5, however upset conditions may occur (e.g. lower pH during digester instability)

• Grit/Sand: Presence of grit and inert material is expected, noting historical accumulation within upstream processes

• Abrasiveness: Moderate, due to grit and inorganic content

• Volatile Content: Typical of aerobic sludge (tenderers to allow for variability)

Installation Conditions

The system will be installed within an existing dewatering building (indoor environment).

Space constraints apply, and integration with existing infrastructure is preferred where practical.

SCADA / Control System

• Existing PLC Platform: Rockwell ControlLogix (e.g. 1756-L72 or similar)

• SCADA System: Currently Citect but soon to be upgraded to ClearSCADA

• Communications: Ethernet/IP preferred, with integration into existing fibre network

• Control Philosophy: Existing centrifuge operates via local control panel with integration to SCADA for monitoring, alarms, and limited control

Tenderers shall ensure compatibility with the existing control system and clearly define any additional hardware, interfaces, or upgrades required

General

Tenderers shall nominate the basis of design, including hydraulic and solids loading assumptions, and demonstrate that the proposed equipment meets or exceeds the performance of the existing system across the expected operating range.

Target cake solids =18–22% DS

Target solids capture =95%

Question:
Are you able to provide the sludge inlet flowrate capacity of the existing dewatering plant.

Are you also looking for a skid mounted or containerised system?

Answered on 07/Apr/2026 09:54 AM:


Sludge feed pumps have a maximum capacity of 20 L/s.

Current typical operation is approximately 12 L/s at ~1.4% w/v sludge concentration.

Tenderers should base designs on the maximum available pump capacity.

A skid-mounted system is preferred; however, solutions utilising existing infrastructure will also be considered.

Target cake quality =18–22% DS

Question:
Hello - is there any information about:

- the number of hours per day or per week the new sludge equipment will operate

- the volumetric flow rate range of sludge (in m3/hr) and the mass flow rate of sludge (in kg-DS/hr)

Answered on 07/Apr/2026 09:54 AM:


Nominal centrifuge run time is approximately 60 hours per week.

The current hydraulic design is approximately 54 m³/hr at ~1.4% w/v sludge concentration, equating to approximately 400–420 kg DS/hr.

Question:
Hi,

We note from the RFQ that "Tenderers must design solutions that meet or exceed the performance envelope of the existing centrifuge system". We also note that some Baseline Reference data from the existing centrifuge has been provided.

The question is:

What is the hydraulic throughput in l/s or m3/hr of the existing centrifuge? Is there data available off a flow meter or what is the existing pump maximum capacity/current duty?

Ideally we would like to know the design flow rate corresponding to 1.5% DS & also the design flow rate corresponding to 3.0% DS? All dewatering machines are both solids & hydraulically limited.

Also can we have a copy of the existing drawings for site plan/elevation and if possible overall pictures to see if our dewatering solution can fit in the existing infrastructure?

Ideally we can get answers next week prior to the site inspection to see if we should attend.

Thanks

Answered on 07/Apr/2026 09:59 AM:


The current system hydraulic design is approximately 54 m³/hr at ~1.4% w/v sludge concentration.

Typical operation is approximately 12 L/s (˜43 m³/hr), with a maximum available pump capacity of 20 L/s (˜72 m³/hr).

At 1.4% w/v, this equates to approximately 400–420 kg DS/hr.

At higher solids concentrations (e.g. 3%), tenderers should consider solids loading limitations when proposing equipment.

Tenderers must demonstrate that proposed equipment can meet or exceed the existing system performance across the expected operating range.

Solutions that integrate within existing infrastructure are preferred; however, alternative configurations will be considered where justified.

Existing drawings and site information will be provided as Addendum #1

Question:
Hi Team,

Can you please provide the technical data sheets for the existing centrifuge?

Answered on 22/Apr/2026 08:23 AM:


Please refer to issued addendum 2

Question:
Dear Wagga Wagga City Council,

Could you please respond to the following queries:

1. Please advise size of existing polymer powder batching tank?

2. Please advise size of existing polymer powder solution tank?

3. Please supply screen shots of your DCS/Scada, capturing 1. The biosolids bin, 2. The decanter, 3. The polymer batching and dosing system

Answered on 28/Apr/2026 03:06 PM:


Question 1: Batching tank is approx. 9kl volume and about 5 meters tall with radius 1.5m.

Question 2: Powder tank is a 40 tonne hopper. Approx. 8 meters tall and 2.5m radius

Question 3: Please refer to Addendum 3 issued today 28 April 2026