"Burnett Water Pty Ltd Eidsvold Weir EIS ALTERNATIVES TO"
Burnett Water Pty Ltd Eidsvold Weir EIS 4. ALTERNATIVES TO AND NEED FOR THE PROPOSAL The Central Burnett Region (comprising Biggenden, Gayndah, Mundubbera and Eidsvold Shires) is heavily dependent on the primary industries sector for economic prosperity and growth, with over 42% of the workforce employed in Agriculture, Forestry and Fishing (BIEDO, 1998). Irrigated horticultural and agricultural enterprises make a very important contribution to the sector, particularly in the Mundubbera and Gayndah Shires. Some 64% of the value of agricultural production in the Central Burnett is derived from irrigated land so that the region is dependent on good quality water supplies. The higher reliability of production and local employment associated with irrigation enterprises as compared with rainfed enterprises is an important factor in maintaining investor confidence in rural communities. Moreover, increased economic stability and growth prospects will also have favourable social implications; e.g. through better retention of young people in the community, reduced unemployment and availability of services in the town. An appreciable proportion of the horticultural production, particularly citrus, is exported so existing irrigation developments contribute to national export earnings as well as to the Queensland economy. In addition, urban and industrial developments are dependent on the availability of water supplies. The three Shires of Eidsvold, Mundubbera and Gayndah have a total allocation for urban use of 1,670 ML and 1,577 ML were delivered against this allocation in 1998-99 (State Water Projects, 1999). This utilisation level of over 94% effectively leaves very little margin (i.e. ~6%) available for future urban or industrial growth. All water available from existing storages in the Burnett is committed already. Water allocations, including those for urban centres, in the area served by the Upper Burnett Water Supply Scheme total 27,954 ML and deliveries totalled 26,865 ML or over 96% of allocations in 1998-99 (State Water Projects, 1999) again illustrating the lack of available supplies to support further economic growth and underpin prosperity. DNRM (2001) Report contains the results of a 1993 survey by the Steering Committee of the Central Burnett 2005 Study to assess estimated future demands from existing and potential water users. The total quantity of water requested in the section from Wuruma Dam to Degilbo Creek over a ten-year period was 15,700 ML with 10,500 ML being a priority requirement within five years. Because of failure of supplies from Wuruma Dam in 1995/96 and from the start of 1999/2000 to the present, and restricted supplies over other periods since 1993, it is highly likely that demands have increased substantially since the survey. DNRM (2001) have estimated the potential demand for irrigation water based on full development of irrigable soils. Estimates for the area within 5 km of the Burnett River between the Nogo River and Degilbo Creek are given in Table 4. Status – Final Draft 31 September 2001 Project Number – 831/000259 Our Ref − draftreport-vers04.doc Burnett Water Pty Ltd Eidsvold Weir EIS Table 4. Potential demand for irrigation water based on full utilisation of available soils with an average water use of 5.8 ML/ha River reach Total area of Regulated Additional area Additional irrigable soils licensed area for water (ha) (ha) development requirement (ha) (ML) Nogo River to Mundubbera 7,850 2,220 5,630 32,650 Mundubbera to Gayndah 8,070 1,120 6,950 40,310 Gayndah to Degilbo Creek 10,240 770 9,470 54,930 Total 26,160 4,110 22,050 127,890 Source: DNRM (2001) The 1993 survey of potential water users indicates that there is appreciable demand for the water that will become available for irrigation as a result of the project and Table 4 shows that there are more than adequate reserves of suitable land to use the water. In addition, Mundubbera Shire Council has indicated that they have an urgent requirement for an additional 200 ML of high priority water to remove the need for repeated annual negotiations with Gayndah Shire Council for temporary transfers of allocation. Further supplies are likely to be sought to support future urban developments. Eidsvold Shire has a water allocation of 350 ML and water use is currently around 290 ML or 83% of the allocation. Thus it is anticipated that an increase in allocation or some reserve of high priority water to be set aside as a result of the project will be sought. However, the matter has not been considered by Council so that no estimate of volume is available at present. Council will be seeking an allocation to support an integrated aquaculture/cabinet timber production project as well. This project is anticipated to underpin a more permanent employment base for the town in future. The majority of the town’s workforce is currently employed seasonally in the fruit industry. Alternatives to the project may be considered in terms of alternative sources of water and alternative water storage options. The likely feasibility of a number of alternative sources of water are summarised in Table 5. More detail on some issues may be found in DNRM (2001). Available alternatives only yield small volumes of water in comparison with those from the proposed project and/or provide water at a high cost. Table 5. Feasibility of alternative sources of water Source Notes on feasibility Demand management § Water shortages in recent years have forced irrigators to improve efficiency of water use through practices such as trickle or microspray irrigation of tree and vine crops so potential gains are small § Urban water use in the catchment is a small proportion of total water use – DNRM state that a 20% reduction in urban demand across the whole catchment would reduce water use by only 3,600 ML Rainwater tanks § DNRM (2001) indicate that rainwater tanks could supply only 9% of total urban demand at a capital cost of $56,000 /ML of yield ($56 /KL) § Quality of rainwater from tanks may be poor and first flush and Status – Final Draft 32 September 2001 Project Number – 831/000259 Our Ref − draftreport-vers04.doc Burnett Water Pty Ltd Eidsvold Weir EIS Source Notes on feasibility disinfection systems may be required for potable use § Rainwater tanks are already used on almost all rural properties and in some towns such as Mundubbera where aesthetic qualities of reticulated water have been poor from time to time Greywater reuse § DNRM (2001) indicate that greywater requires treatment before use and that the capital cost of systems would be $23,000 to $69,000 /ML of yield – 7,450 ML/a could be saved by full implementation across the catchment by 2025 Wastewater reuse § Mundubbera wastewater is used for golf course irrigation already § Reuse of 90% of wastewater for irrigation would yield about 6,000 ML/a at present at a capital cost of between $4,600 and $13,800 /ML (DNRM 2001) Urban stormwater harvesting § Reliable estimates of cost are not available § Applicability in the Eidsvold to Gayndah area is limited because of small urban centres On-farm storages § Capital cost of ring tanks (1,454 ML capacity) is estimated at $963 /ML of yield (DNRM, 2001) § Additional capital costs are incurred for high-capacity pumping systems to fill storages § Additional operating costs are associated with the double handling of water on-farm (filling then irrigating as a separate operation) Alternative storage sites in the Central Burnett were examined by Hyder (1998). Their study looked at the following proposals: § dam on the Auburn River at AMTD 14.4 km, 18.8 km or 22.5 km; § weir on the Auburn River at AMTD 4.64 km; § weir on the Burnett River between AMTD 290 km and 312 km; and § dam on the Burnett River between AMTD 317 km and 366.6 km. Dam sites at AMTD 18.8 km and 22.5 km on the Auburn River were eliminated because any dam with appreciable storage capacity at these sites would have a significant impact on conservation values within the Auburn River National Park. A dam at AMTD 14.4 km would be constrained by impacts on the National Park but could still increase system yield at Jones Weir by an estimated 23,700 ML/annum at an estimated cost of $2,776 /ML. It was found that a weir on the Auburn River at AMTD 4.64 km could yield 5,600 ML/annum at low reliability of supply and an estimated cost of $1,100 /ML. However, it was concluded that closer economic study was required. Seven storage options along the Burnett River were examined by Hyder (1998) and the outcomes of their evaluations are summarised in Table 6. Where more than one full supply level was considered at any site, that with the lowest cost per megalitre of yield of high reliability water is considered. The Consultant put the AMTD 300.4 km site forward as the preferred weir option on the basis of similar performance and environmental impacts to the AMTD 296.8 km site and lower cost. It was noted that further geotechnical investigations should be undertaken before adoption of the site as a final choice. Status – Final Draft 33 September 2001 Project Number – 831/000259 Our Ref − draftreport-vers04.doc Burnett Water Pty Ltd Eidsvold Weir EIS Table 6. Summary of the evaluation of alternative storages in the Central Burnett Site / Issue Evaluation Dam at AMTD 366.6 KM Engineering § Rock about 10 m under alluvium § Saddle dam required on left bank Yield and cost § 19,400 ML at $3,206 /ML Terrestrial flora and fauna § No extensive tracts of remnant native vegetation § Narrow and fractured riparian zone § Similar to weir sites near Eidsvold Aquatic flora and fauna § Flood plain and a number of off-stream pools associated would provide a wide diversity of high quality habitats § Natural flows downstream would be reduced appreciably Cultural heritage § No sites of significance identified by study § Community consultation and an archaeological field survey would be required Socio-economic § Some 11,000 ha of land suitable for irrigation downstream § Appreciable resumption costs Dam at AMTD 317.0 km Engineering § Weathered rock outcrops on both abutments § Suitable for an RCC gravity dam Yield and cost § 74,000 ML at $1,277 /ML Terrestrial flora and fauna § No extensive tracts of remnant native vegetation § Narrow and fractured riparian zone § Similar to weir sites near Eidsvold Aquatic flora and fauna § A number of off-stream water bodies (small tributaries) along the waterway § Stream partly covered by riparian vegetation § Impoundment will result in loss of a number of high quality habitats Cultural heritage § Impoundment would drown Ceratodus railway station § Community consultation and an archaeological field survey would be required Socio-economic § Severe impacts include inundation of current rail and road routes requiring substantial diversions § Appreciable land resumption costs and loss of land already irrigated Dam at AMTD 293.4 km Socio-economic § Eidsvold to Theodore road would require diversion § Flooding of Eidsvold to Monto road and rail routes would limit storage capacity § Site not investigated further Weir at AMTD 295.3 km Engineering § Up to 6 m of sand and gravel over decomposed or moderately weathered rock § Right abutment would require extensive erosion protection works § River within Quaternary alluvium Socio-economic § Road bridge would have to the carried over the weir with associated costs § Site not investigated further Weir / Dam at AMTD 296.8 km Engineering § Site would be suitable for RCC weir § Site would be suitable for RCC dam with saddle dams up to 70 m long and 21 m high § Longest saddle dam is 700 m § Up to 10 m of to hard rock in the streambed Yield and cost § Dam 40,000 ML at $1,338 /ML § Weir 28,000 ML at $475 /ML or Terrestrial flora and fauna § Tolderodden Conservation Park is downstream and unlikely to be affected Status – Final Draft 34 September 2001 Project Number – 831/000259 Our Ref − draftreport-vers04.doc Burnett Water Pty Ltd Eidsvold Weir EIS Site / Issue Evaluation § Much of the impoundment area for the dam has been cleared or partly cleared § Narrow strips of riparian vegetation remain Aquatic flora and fauna § A number of off-stream pools associate with tributaries § Dam would result in loss of high quality off-stream pool habitats reducing habitat diversity § Weir impacts would be confined to in-stream and riparian habitats Cultural heritage § Close to Eidsvold Station homestead § Local waterhole believed to have cultural significance for Aboriginal people § Community consultation and an archaeological field survey would be required Socio-economic § Weir would be within bed and banks without impacting on neighbouring properties § Better dam sites are available Weir at AMTD 300.4 km Engineering § Materials are similar to those at the 296.8 km site with an alluvial terrace extending about 400 m from the river on the right bank § Interpretation of seismic data indicated a dense layer, apparently moderately weathered to fresh rock under the right bank alluvium § Further geotechnical investigations required § Site is suitable for a mass concrete or RCC weir Yield and cost § 28,000 ML at $418 /ML Terrestrial flora and fauna § Very similar to a weir at the 296.8 km site Aquatic flora and fauna § Very similar to a weir at the 296.8 km site Cultural heritage § Generally similar to a weir at the 296.8 km site § Site may be more acceptable to Aboriginal people than the 296.8 km site Socio-economic § Very similar to a weir at the 296.8 km site Status – Final Draft 35 September 2001 Project Number – 831/000259 Our Ref − draftreport-vers04.doc Burnett Water Pty Ltd Eidsvold Weir EIS Status – Final Draft 36 September 2001 Project Number – 831/000259 Our Ref − draftreport-vers04.doc