OPTION
|
DESCRIPTION
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JUSTIFICATION FOR/AGAINST
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| Potable water pipeline (connection at Gracemere) – recommended option for progression |
Construction of a potable water pipeline connecting the Gracemere and Mt Morgan water supply networks. This option may facilitate further environmental releases from No. 7 Dam into the Dee River. |
This option is a replacement supply, which is, providing volume necessary to supply the full demand for Mt Morgan under ongoing operation. This option enables No. 7 Dam levels to be sustained at higher levels since it is not being used for water supply purposes. The economic evaluation of this option has demonstrated that it is the most suitable solution and is most suitable to achieve a secure supply for Mt Morgan. |
| Do nothing |
Continue to truck potable water from Gracemere network in periods of inoperable water levels within No. 7 Dam. |
This is not a sustainable long term solution. No. 7 Dam does not provide the desired reliability of supply to the community. Council have already spent $4.5 million trucking water to Mt Morgan and this is both economically irresponsible as well as unfair to the people of Mt Morgan. |
| Increased Water Carting |
Increased amount of trucking to increase volumes being delivered. This option would see water delivered directly to the town reservoir similar to current practice once the No. 7 Dam hits the Level 3 restriction trigger level of 30%. |
This option ranked 2nd in score and costs but was shown to have negative benefits as it generates more costs as a result of its operation in comparison to other options. |
| Raw water pipeline (connection to Stanwell Dam) |
Construction of a raw water pipeline fed from the Lower Fitzroy River Water Supply Scheme. This involves connection to the Stanwell Water Supply Dam, with supplementary supplies provided to Mt Morgan. This option is a supplementary supply option, where the existing supply source (No. 7 Dam) is retained within the supply scheme, and new sources provide a supplementary supply of a restricted demand to the Mt Morgan scheme during times where the dam is low, and greater than level 3 restrictions are imposed. Water balance modelling has demonstrated that supplementing the dam to sustain dam levels would require volumes two to three times the demand requirements due to dam evaporation. |
This option was ranked 4th overall in the options assessment and is some 30% more expensive than the recommended option (potable water pipeline) from a whole of life cost perspective, and therefore not preferred.
|
| Raw water pipeline (connection to Sunwater system) |
Construction of a raw water pipeline fed from the Lower Fitzroy River Water Supply Scheme. Involves connection directly to the Sunwater pipeline that supplies the Stanwell Water Supply Dam. Similar to the above raw water pipeline at Stanwell, this option provides supplementary supply of restricted demand to the Mt Morgan scheme during times where the dam is low, and greater than level 3 restrictions are imposed. |
This option was ranked 3rd overall in the options assessment and is some 28% more expensive than the recommended option (potable water pipeline) from a whole of life cost perspective, and therefore not preferred. |
| Raw Water Pipeline (Connection to Stanwell, with Hydropower incorporated into scheme) |
Considers option of raw water pipeline (connection to Stanwell Dam) with Hydropower option. |
Discussions with Stanwell outlined their early investigations into Hydropower involving No. 7 Dam. They noted substantial cost involved in the project and that it was currently unviable. The size of the pipe for a potable water pipeline is approximately 250mm whereas for a hydropower pipe it would be about 3 metres which means the cost would be significantly higher. Typically for a hydropower solution the source needs to be quite close to the point of generation and in this case it is quite far apart so the cost of the capital infrastructure, land acquisitions, plus the pipe size means that there would be substantial costs for this option, making it unviable. |
| Operating Adjustment No. 7 Dam |
Adjust the restriction triggers currently in place on No. 7 Dam to determine whether its reliability is improved in doing so. |
Water balance modelling showed limited improvement in reliability of dam through adjustment of operating rules. This option is unable to meet the required volume of water to the community at the required level of service. |
| Demand Reduction Strategies |
Long term reduction in average water use by the community to potentially improve the incidence of restrictions. This should not be confused with drought management, which requires a specific response to lowering source supply availability and can still be required even if long term demand reductions are achieved. |
Water balance modelling showed that no improvement in reliability of dam through provision of long-term demand reductions. This option is unable to meet the required volume of water to the community at the required level of service. |
| Relocate the town |
Purchase homes in Mt Morgan to enable relocation of residents. |
Option unlikely acceptable to community. Substantial cost to acquire properties in comparison to other options (at least 3 to 4 times more costly). |
| Augmentation of No. 7 Dam |
Raising of No. 7 Dam embankment, structure and spillway to increase storage and reliability of supply. |
Water balance modelling showed that no improvement in reliability of dam achieved through raising of No. 7 Dam. This option is unable to meet the required volume of water to the community at the required level of service. |
| Desilting No. 7 Dam |
Desilting/dredging of No. 7 Dam to improve storage capacity and reliability of supply. |
Water balance modelling was undertaken assuming that the full capacity of the dam was available. Given that it showed that the desired level of service could not be achieved based on full operating capacity, desilting will have no benefit on the water security profile. Desilting may be considered by council for other reasons. |
| Nine Mile Creek Dam |
Construction of a new bulk water storage dam at Nine Mile Creek including pipeline and associated pump infrastructure. |
Per historical investigations for this option, the cost of building a dam at Nine Mile Creek was 3-4 times the cost of a pipeline option to Rockhampton. Regulatory approvals are likely to result in significantly longer delivery timeframes compared to other options. |
| Fletcher Creek Weir Upgrade |
Upgrade of Fletcher Creek Weir and associated infrastructure to increase reliability and supplement No. 7 Dam supply. |
Review of water balance modelling for No. 7 Dam shows that there is no flow in Fletcher Creek once No. 7 Dam reaches low supply levels. There is also evidence to suggest that Fletcher Creek Weir is leaking quite substantially and the current infrastructure would need significant refurbishment. This option is not seen to provide the reliability of supply needed. |
| Desalination Plant at Port Alma |
Construction of a new desalination plant at Port Alma including pipeline and associated pump and bulk storage infrastructure. |
Brine, a by-product of the desalination process, is a known management issue with desalination, which may lead to substantial operational costs should this option proceed. The distance of pipeline required to the Port Alma site is substantially longer than others considered. Due to the expected high cost in comparison to other options, this option has not been considered further. |
| Effluent Reuse |
Use of treated effluent (sewage) from Mt Morgan and/or Gracemere Wastewater Treatment Plants. |
Insufficient water volumes available; unlikely to be accepted by community; additional treatment required; and due to treatment, civil infrastructure and ongoing management needs it is likely to be cost prohibitive. |
| Groundwater |
Replace existing supply from No. 7 Dam with use of existing or installation of new ground water bores. |
Insufficient water volumes available to meet the required volume at the required level of service. Quality issues with supply have also been identified historically. |
| Offtake on Fitzroy to Gladstone (F2G) Pipeline (raw/partially treated water) |
Connection to the proposed Fitzroy to Gladstone pipeline including pipeline and associated pump and bulk storage infrastructure. |
With uncertainty around project timing for the F2G, there is potential that it would not be available in a timely manner to provide relief to Mt Morgan. The F2G project is presently not funded by the state. There is a cost risk to the Mt Morgan water project should the F2G project not proceed, since RRC may need to provide additional upstream infrastructure within the timeframe which RRC requires. Further, preliminary hydraulic analysis indicates that additional pumping infrastructure would be required due to topography along potential route from F2G to Mt Morgan. Therefore this option is not considered suitable.
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| Individual rainwater tanks |
Installation of privately owned rainwater storage tanks at individual properties to reduce demand/replace supply. |
Water balance modelling of rainwater tanks showed minimal benefit for supply due to the local climate. |
| Mine water reuse |
Utilise existing mine-pit water from decommissioned gold mine including pipeline and pump infrastructure. |
The volume available from this resource is expected to be a fixed volume and would be depleted over time. There is also further uncertainty if this water would be available due to the proposed reprocessing of tailings by Heritage Minerals. Further, this option was previously ruled out through community consultation. |