COONABARABRAN GROUNDWATER PIPELINE

8kms of 250mm PVC Rising Mains – and associated infrastructure

Coonabarabran’s water supply is sourced from the Timor Dam located on the Castlereagh River and several bores located along the route of the existing pipeline from the Dam to Council’s Water Treatment Plant (WTP). The existing DN250 DICL supply pipeline is old and has recently had some major repairs carried out to keep the pipeline operational.

Warrumbungle Shire Council intends to commission the Design and Construction of Stage 1 of a new PN16 DN250 OPVC Series 2 pipeline from the Timor Dam to the WTP to provide greater flexibility in the operation of the pipeline to supply water to the WTP.

The new pipeline would provide a redundancy in the existing supply pipeline due to a failure in the main or during routine maintenance. The new groundwater pipeline will increase Council’s flexibility in the management of poor water quality from the Timor Dam during floods or algal events. The new pipeline will allow the supply water to the WTP even when the water in Timor Dam is very low or the Dam is empty. A concept design was prepared of the groundwater pipeline from the Timor Dam to the WTP.

Whilst the concept design has been completed for the full length of the pipeline, the pipeline will be constructed in 2 stages:

Stage 1 from the Bart Bok Bore (Bore No.11) located at Chainage 3550 to the WTP at Chainage11595. Stage 1 of the project is to be carried out first an approximate length of this section of the pipeline is 8.0km.
Stage 2 from Timor Dam to the Bart Bok Bore (Bore No.11). The approximate length of this section of the pipeline is 3.2km. Stage 2 of the project was not included in this Contract.

The project was undertaken through funding made available through NSW Water Security for regions program.

Works Undertaken

• 8.0km of 250mm PN 16 PVC Rising Mains from Bart Bok Bore to Coonabarabran WTP.
• 20 required Isolation Valves, Air Valves and Scour Valves along the pipeline route
• Under bore 3 major Creek crossings various lengths up to 250mrts under bore
• Castlereagh River crossing was connected to the side of the bridge in 250mm DICL
• Interconnect 250mm PVC main to existing 250mm AC including all isolating valves
• Connect all 3 Bores along the pipeline route to the new pipeline including all required fittings.
• Connect 12 Residential properties to the pipeline along the route.
• Concrete Thrust Pit at WTP to interconnect both pipelines and control possible Water Hammer through Surge Anticipation Valve
• Testing and Commissioning of Pipeline in 2km sections.

Highlights, Innovations and Key Risks

• Project finished on budget even with major wet weather delays and rock obstruction
• No major disruption to town water supply through the project duration
• Major infrastructure branch connection at end of 250mm main into existing 250mm AC
• RMS Road daily traffic management along roadside to eliminate traffic delays
• No underground service strikes for the duration of the project
• 3 branch roads to cross without causing traffic delays