Question:
Upon reviewing the RFQ document, we’ve found that the information provided is currently insufficient for us to proceed with selecting and pricing the appropriate blowers.

Could you kindly provide a summary with the following details to assist us in sizing and quoting the units accurately:

• Operating flow and pressure required for each blower - we do note that some pressures have been provided but to minimise any errors, if it can be clearly stated

• Ambient conditions

• Inlet/outlet configurations

• Site Elevation (ASL)

Thanks,

Answered on 08/Aug/2025 11:51 AM:


1. Operating Flow and Pressure

Narrung Street WWTP

• Flow: 2,930 m³/h total (Duty/Duty configuration – 2 blowers operating concurrently for Digester 1 and Digester 2)

• Pressure: 45 kPa at blower discharge

Kooringal WWTP

• Blower 1: 3,068 m³/h (constant duty – supplies both digestion and air scouring for tertiary filter backwashes)

• Blowers 2 & 3: Duty/Standby for digestion only 1,000 m³/h

• Pressure: 30 kPa at blower discharge

Note: Flows are based on current operational requirements. Tenderers are encouraged to allow for reasonable headroom for operational flexibility.

2. Ambient Conditions

• Typical maximum temperature: ~40 °C

• Typical minimum temperature: ~–4 °C

• Relative humidity: Can be high during certain periods; equipment should be suitable for outdoor operation with protective enclosure

3. Inlet / Outlet Configuration

• Inlet: Current blowers draw from ambient plant room air through inlet filters.

• Outlet: Discharges to fixed process pipework for each digester air grid.

• Pipework arrangement may vary slightly between sites; tenderers should allow for inspection during site visit or allow flexibility in connections

4. Site Elevation (ASL)

• Narrung Street WWTP: ~147 m above sea level

• Kooringal WWTP: ~182 m above sea level

Please ensure that all flows are quoted in Nm³/h referenced to:

• 0°C (273 K)

• 1 atm (101.325 kPa)

• 0% relative humidity

If alternative reference conditions are used, please state clearly.

Question:
Hi,

Could you please supply the following:

1. SCADA air trends for both WWTPs (if available)

2. Input power of PDA NX26 at Narrung Street WWTP

3. Input power of PDA SN806 & PDA SN811 at Kooringal WWTP

Would you consider the following:

1. Narrung Street WWTP: 1 duty blower (duty/standby – instead of duty/duty) - we have 60kW blower that can delivery / supply for digester 1 and 2 however the switchboard will need to be upgraded (2,930 m³/h at 45kPa, the input power of our blower is 44.8kW).

2. Kooringal WWTP: 2 duty blowers (duty/duty/standby – instead of duty/duty/duty) – with the same blower as Narrung, 1 machine running at 3,068m³/h at 30kPa the power input is 35.6kW.

These units consistently operate high on their performance curve, resulting in excessive wear, increased energy consumption, and shortened asset life, could you please clarify this as we would like to know where the blowers will need to operate.

Info from the process designs:

Narrung Street WWTP: Select blower to deliver 2,930 m³/h at 45kPa each.

Kooringal WWTP: for blower 1 to deliver 2,068 m³/h at 30kPa; 1,000 m³/h at 30kPa for blower 2 and 3.


Thank you.

Answered on 07/Aug/2025 01:00 PM:


Please note the following:

1. We have no aeration trends on the digesters

2. Input power for Narrung Blowers is 80kW at 65kPa and 31kW at 45kPa (Backwash)

3. Input Power PDA806 14kW and PDA SN811 19kW at designed air flow requirement

The input power figures provided reflect current operating conditions; however, the key parameter to consider is the design air volume delivery.

1. Narrung Street WWTP

Council's current blower operation is configured as duty/duty, with both digesters requiring independent and reliable air supply due to variable loading and the need for redundancy. Proposals suggesting a duty/standby configuration will be considered only where:

- The proposed blower can demonstrably meet the combined air demand of both digesters under peak conditions (2,930 m³/h at 45 kPa). Digester blower 2 is used for air scouring of Tertiary filters and must be able to be turned down when performing this duty (1500 Nm³/h).

- Any required switchboard upgrades are clearly specified and included in the submission.

- The risks associated with blower failure are addressed with appropriate contingency measures.

2. Kooringal WWTP

The existing arrangement consists of:

- Blower 1: Constant duty and also provides air scouring for tertiary filter backwashes.

- Blowers 2 and 3: Operate in a duty/standby configuration for digester aeration.

Any proposal to move from the current duty/duty/duty setup to a duty/duty/standby configuration must consider:

- The criticality of Blower 1 and its dual role in supporting both digestion and backwash operations.

- The need for reliable concurrent operation during high load conditions or during filter cleaning cycles.

- Confirmation that two blowers operating concurrently (at proposed capacities) can meet combined process and backwash air demands.

Important Note to All Tenderers:

Council is open to alternative configurations that provide operational, energy, or cost efficiencies. However:

- Any proposed variation from the specified configuration must be clearly outlined and justified.

- A fully conforming submission (based on the original RFT specification) must also be provided for evaluation.

- Non-conforming or alternative tenders that are not accompanied by a conforming bid may not be considered.

Question:
The figures listed in the specification don’t indicate the flows required. We need to know the flow requirements , minimum & maximum for the systems in question for both sites .

Also, we need to know the existing running pressures of each plant.

Depth of water does not indicate the true pressure required for each unit..

Then we need to know how much extra air flow is required above the limit of the existing units.

We need to plan for future expansion.

Need to understand the reference conditions

Are we working on Am3/hr or Nm3/hr.

What is the reference condition for each site.

Nm3/hr should be 273 k [0 degC ]

Am3/hr 15 degC or 20 degC

Thanks for your help with this

Answered on 07/Aug/2025 01:03 PM:


Please note the following clarifications:

1. Flow Requirements – Narrung Street WWTP

- Design Airflow Requirement: 2,930?m³/h (each digester)

- Operating Configuration: Duty/Duty (2 blowers operating concurrently one for each Digester)

- Digester Blower 2 provides air scouring for Tertiary Filters

- Pressure Requirement: 45?kPa at blower discharge

- The specified figure reflects actual operational demand, not a minimum/maximum range. A margin above this flow rate is recommended for future flexibility but has not been quantified within the tender.

2. Flow Requirements – Kooringal WWTP

- Design Airflow Requirement (Blower 1): 2,068?m³/h

- This blower supports both digestion and air scouring for tertiary filter backwashes

- Blowers 2 & 3: Operate in duty/standby for digestion only requirement 1,000m³/h

- Pressure Requirement: 30?kPa at blower discharge

Please allow for an appropriate safety or future capacity margin in your proposal based on standard industry practice, as WWCC has not specified an exact expansion allowance.

3. Reference Conditions

Unless otherwise stated:

- Flow values should be provided as Nm³/h, referenced to:

- 0°C (273 K)

- 1 atm (101.325 kPa)

- 0% relative humidity

If your proposal uses different reference conditions (e.g. Am³/h at 15°C or 20°C), please state this clearly and include conversion assumptions.

4. Running Pressures

The nominal discharge pressures required are as listed above (45?kPa and 30?kPa respectively). These figures are based on actual operating conditions, including pipe losses, diffuser depth, and system backpressure. You are correct that water depth alone does not determine final blower pressure. If your proposal includes variations, please provide supporting detail and technical justification

5. Expansion Capacity

Council encourages designs that allow for moderate future capacity increases (e.g. through VSD capability or scalable unit selection). While future loading projections are not part of this tender, blower sizing that incorporates a 10–15% headroom above current demand would be considered appropriate.

Please ensure any assumptions made in your response are clearly identified, including reference conditions and flow units.

Question:
Hi Team,

The tender documents have contradicting information with that relates to the blowers capacity relevant to Normal (N)m3/hr flow rates and m3/hr flow rates.

The two flow rates differ as one relates to volume of air a and the other relates to volume of gas in a normal cubic meter of air.

It is critical we know both clearly so the sizing of the new blowers can be accurately selected to ensure that they are capable of delivering the correct oxygen demand to the reactors to meet the biological oxygen demand, not just the volume demand. Although there is information in the tender documents, the wording and data provided contradicts our calculations.

Can Wagga Wagga City council provide the individual requirements for each blower, for Normal (N)m3/hr flow rates and m3/hr flow rates asap so we can clearly understand these two measurements so we can size thew correct blowers.

Answered on 15/Aug/2025 12:52 PM:


Please refer to issued Addendum 3

Question:
Hello,

Kooringal WWTP .... (Addendum No.3 Issued 15/08/2025)

Digester 1 - 30kPa

Please confirm if Air Flow 3068 Nm3 per hour is correct as referenced in this addendum...... I see council in a earlier reply dated 7 August at 01:02PM advised this to be 2068 m3 per hour which when converted to Nm3 per hour is in the order of 1700 Nm3 per hour.

Thank you in advance

Answered on 21/Aug/2025 08:19 AM:


Please refer to issued Addendum 4 for correct Air Flow.