Queensland Water Commission

Transcription

1 Prepared for Queensland Water Commission Reuse of Purified Recycled Water in South East Queensland Rep eport March 2008 Reference:

2 CH2M HILL Australia Pty Ltd Level 1, 33 Park Road MILTON QLD 4064 Phone Fax This document may only be used for the purpose for which it was commissioned; and in accordance with the Terms of Engagement for the commission. This document should not be used or copied without written authorisation from CH2M HILL Australia Pty Ltd. March 2008 Ref: i

3 Executive Summary Report Purpose The South East Queensland Regional Water Supply Strategy (SEQ RWSS) identified a number of options for utilizing purified recycled water (PRW) to supplement municipal water supplies. One such scheme is the Western Corridor Recycled Water Project (WCRWP). This project is already under construction and involves the establishment of advanced water treatment plants (AWTPs) at Luggage Point, Gibson Island and Bundamba. Some of the PRW from the WCRWP will be pumped to Wivenhoe Dam for reuse as part of the yield from that dam through the Mount Crosby water treatment plant. The wastewater treatment plants (WWTPs) supplying the WCRWP account for about 45% of the total WWTP discharges in SEQ. There are a number of other WWTPs in SEQ that have the potential for the production of significant quantities of PRW. The purpose of this study is, therefore, to determine the full potential of these other plants to contribute to the supply of PRW. In particular, the study identifies reuse schemes additional to the WCRWP which could cost effectively maximize the reuse potential. It is noted that this is a scoping report which attempts to only provide an initial screening of reuse schemes. A number of assumptions have been made in its preparation and no attempt has been made to optimise the identified options. Further detailed site specific investigations would be required to prove the viability of potential schemes identified in this report. Recycled Water Flow Estimates There are 61 wastewater treatment plants (WWTP) in SEQ which discharged about 247,000 ML/a of treated effluent prior to the current drought. The discharge rates for each treatment plant have been adjusted to the future estimated non-drought discharges, assuming the average non drought water consumption will then be 230 L/c/d. These values have then been projected through to 2051 to obtain an estimate of the 2051 treatment plant effluent discharges. These estimates were prepared on the basis of there being a strong correlation between average sewage discharges and water consumption rates. Growth projections through to 2026 were prepared using PIFU growth data. Projections for the period 2026 to 2051 used growth projections previously prepared in conjunction with the Queensland Water Commission for the estimation of future water demands. The estimated total discharges in 2026 and 2051 are 357,000 and 443,000 ML/a. About 7% of the current discharges from WWTPs is recycled, the majority of which is used for park and recreational area irrigation. It is suggested that in times of drought all WWTP discharges, other than recycled water which has a commercial or an essential environmental function, should be considered as a potential source for production of PRW. It is estimated that approximately 207 ML/d of recycled water will be required for commercial and essential environmental purposes (including power station cooling) by Taking this into account it is estimated that there is the potential to produce 204,000 ML/a of PRW in 2026, and 265,000 ML/a of PRW in The actual availability March 2008 Ref: ii

4 is likely to be slightly less as some of the smaller WWTPs in the Bremer, Logan and Albert River valleys have existing commitments to supply rural customers. PRW Production The PRW would be produced at AWTPs. There are a number of process options that may be suitable but the process configuration adopted for the Western Corridor AWTPs is well suited for the construction of other plants that may be constructed in the future. The treatment process involves micro filtration, reverse osmosis and advanced oxidation processes. The Western Corridor AWTPs are at the leading edge of water recycling plants world wide and experience gained with the design, construction and operation of these plants will enable ongoing improvement and refinement. For this study it has been assumed that treatment process adopted for production of purified water for new plants will be similar to that adopted for the Western Corridor Recycled Water Project AWTPs. Identification of Possible PRW Schemes There are 17 existing and proposed surface water storages which have been identified as potential recipients of PRW. Aquifer storages on Bribie and Stradbroke Island have also been identified. The aquifers and storages will provide an environmental buffer for the overall supply system. Whilst there are no hard and fast rules that delineate requirements for inclusion of such environmental buffers in the overall design of systems producing PRW, a conservative approach has been adopted for this study. Thus for estimating the annual volumes of PRW that can be discharged to existing or proposed storages, it has been assumed that there should be a minimum of twelve months detention of the PRW in the storage prior to use and that the percentage of PRW in the storage should not exceed 40%. These criteria are conservative and based on consideration of practices adopted by other water authorities around the world. Further assessment of the criteria is strongly recommended should the proposals be considered further. Whilst these criteria are conservative they have been useful for assessing which schemes may be workable, and which schemes may not. An Excel model was prepared to assess the mixing and detention times which would be achieved with the PRW being directed to the available storages. The model assumed that the storages were full at the commencement of the introduction of recycled water, and that no rainfall/run-off inflow occurred during the modelling period. The assumption of no rainfall/run-off inflow to the storages is a very conservative assumption even in a drought period. Outflows from the storages were estimated in accordance with projected high water savings scenario as outlined in the document Regional Water Needs and Integrated Urban Water Management Opportunities Report. In general, a recycled water scheme was considered to warrant further consideration if the storage could take recycled water for two or more years while achieving the criteria specified above. The Excel model used for the analysis makes no allowance for the dynamics of the water in the storage as it assumes that uniform mixing occurs. The model, however, is useful for screening of options in the first instance, but should investigations proceed detailed hydrodynamic modelling should be undertaken such as has been undertaken for the Wivenhoe Dam. The following possible schemes were investigated and modelled: March 2008 Ref: iii

5 Wivenhoe and Somerset Dams All Brisbane (excluding Sandgate), Esk, Fernvale and Ipswich WWTPs; All Brisbane (excluding Sandgate), Esk, Fernvale, Ipswich and Loganholme WWTPs; and All Brisbane, Esk, Fernvale, Ipswich, Loganholme, Beenleigh and Redlands WWTPs. North Pine and Kurwongbah Dams All Pine Rivers, Redcliffe, South Caboolture and East Burpengary WWTPs; and All Pine Rivers, Redcliffe, Sandgate, East Burpengary and South Caboolture WWTPs. Hinze Dam All Gold Coast WWTPs; and All Gold Coast WWTPs excluding Beenleigh. Baroon Pocket & Ewen Maddock Dams Kawana, Caloundra and Landsborough WWTPs; and All Maroochydore WWTPs (excluding Kenilworth), and Kawana, Caloundra and Landsborough WWTPs. Cooby, Cressbrook and Perseverance Dams Wetalla WWTP. Wappa, Cooloolabin and Poona Dams Nambour WWTP. Leslie Harrison Dam Capalaba WWTP. Lake MacDonald Noosaville WWTP. Wyaralong Dam Beaudesert North WWTPs; Beaudesert North and Loganholme WWTPs; and Beaudesert North, Loganholme and Beenleigh WWTPs. Traveston Crossing Dam Stage 1 Maroochy WWTP Traveston Crossing Dam Stage 2 All Maroochydore WWTPs (excluding Kenilworth), all Caloundra WWTPs (excluding Maleny) and Noosaville WWTP. Each option was modelled for both the 2026 and 2051 PRW inflows and the estimated water supply demands noted above. Table E1 summarises the findings. March 2008 Ref: iv

6 Table E1 Preferred WWTP Discharge and Storage Recipients for Further Investigation Recycled Water Flow (ML/d) WWTP Storage All Brisbane (excluding Sandgate), Esk, Fernvale, Ipswich and Loganholme WWTPs All Gold Coast WWTPs excluding Beenleigh WWTP All Maroochydore (excluding Kenilworth), all Caloundra (excluding Maleny) and Noosaville WWTPs Wivenhoe Dam Hinze Dam Traveston Crossing Dam Stage All Pine Rivers, Redcliffe, Sandgate, East Burpengary and South Caboolture WWTPs Capalaba, Thorneside, Cleveland and Victoria Pt WWTPs North Pine Dam and Lake Kurwongbah Leslie Harrison Dam and North Stradbroke Island aquifer Wetalla WWTP Beaudesert North WWTPs excluding Loganholme WWTP Cooby, Cressbrook and Perseverance Dams Wyaralong Dam Bribie Island WWTP Bribie Island aquifer 3 3 Totals: 596 (217,564 ML/a) 768 (280,320 ML/a) The WWTP/storage combinations that were not considered suitable were: Baroon Pocket & Ewen Maddock Dams: The discharge of some of the recycled water from the Caloundra and Maroochydore WWTPs to these dams is feasible, while meeting the suggested criteria. However, the option of discharging to the Traveston Crossing Dam (Stage 2) comfortably met the mixing and detention criteria without any discharge restrictions. Discharge to the Traveston Crossing Dam would only require one point of discharge whereas discharge to the Baroon Pocket and Ewen Maddock Dams would require some form of flow splitting to the two receiving storages. The Traveston Crossing Dam option was therefore preferred even though it likely that it could not be fully utilized until Stage 2 was constructed. Wappa, Cooloolabin and Poona Dams: The discharge of recycled water from just the Nambour WWTP resulted in exceedance of the suggested mixing criteria. This option was therefore rejected because it was unlikely to be an economical proposal. As for the discharge to the Baroon Pocket and Ewen Maddock Dams, there would also be operational problems of having to split recycled water discharges between at least the Wappa and Cooloolabin Dam storages. Lake MacDonald Dam: The discharge of recycled water from the Noosaville WWTP resulted in exceedance of the suggested mixing criteria. This option was therefore rejected because it was unlikely to be an economical proposal. March 2008 Ref: v

7 Wyaralong Dam: The inclusion of discharges from the Loganholme and Beenleigh WWTPs with that from Beaudesert North resulted in an acceptable mixing criteria up to However, the projected high rate of growth in North Beaudesert after 2020 resulted in exceedance of the criteria by 2051 when combined with inflow from the Loganholme and/or Beenleigh WWTPs. Table E1 shows the estimated annual totals of recycled water discharges to the SEQ dams and aquifers for the preferred schemes. The estimated values of 217,564 ML/a in 2026 and 280,320 ML/a in 2051, represents a potential increase in annual yield over SEQ s existing and planned supply resources (including Traveston Crossing Dam Stage 2) of 34% and 44% respectively. It is noted that these potential increases in yield could reduce in times of extended drought, i.e. droughts extending for more than two years, if the suggested dilution and detention criteria were exceeded. An accurate estimate of the additional yield for each scheme can only be estimated by carrying out a daily water balance model using actual rainfall and evaporation records and the estimated daily PRW inflows and water supply demands. Preliminary Scheme Cost Estimates Preliminary cost estimates have been determined for the preferred schemes other than the WCRWP which is currently under construction. Cost estimates for the preferred schemes are listed in Table E2. TableE2 Recycled Water Reuse Preferred Scheme Cost Summaries Scheme/ WWTP Storage 2026 Purified Recycled Water Flow (ML/d) Scheme Capital Cost ($M) Scheme NPV Cost ($M) Scheme Levelised Cost ($/kl) North Pine Scheme - All Pine Rivers and Redcliffe, Sandgate, East Burpengary and South Caboolture WWTPs Gold Coast Scheme - All Gold Coast WWTPs All Gold Coast WWTPs excluding Beenleigh. Sunshine Coast Scheme - All Maroochydore (excluding Kenilworth), all Caloundra (excluding Maleny) and Noosaville WWTPs Redlands Scheme - Capalaba, Thornside, Cleveland and Victoria Pt WWTPs North Pine Dam and Lake Kurwongbah Hinze Dam Traveston Crossing Dam Stage 2 Traveston Crossing Dam Stage 1 Leslie Harrison Dam and Stradbroke Island aquifer (2051) Wyaralong Dam Scheme - Beaudesert North WWTPs Wyaralong Dam Toowoomba Scheme - Wetalla WWTP Cooby, Cressbrook and Perseverance Dams March 2008 Ref: vi

8 These estimates have been primarily prepared to only allow determination of the overall first order costs, and to economically rank the effectiveness of each scheme. The comparison of schemes has been by levelised costs. These have been determined using a 25 year discount period and a 7.5% p.a. discount rate. The lowest cost scheme when compared on a levelised cost basis is the Gold Coast scheme. However, if it is not possible to utilise the Tugun brine outfall pipeline which is being constructed as part of the Gold Coast desalinization project, the cost of this scheme (and NPV of the water produced) would increase. The next lowest scheme (in levelised cost terms) is the Sunshine Coast Scheme. This scheme would rely on Stage 2 of the Traveston Crossing Dam being constructed and as such would not be expected to be developed before The first stage option utilizing purified water from the Maroochydore WWTP is not cost effective, due to an assumption that infrastructure constructed at the first stage would be sized for future expansion. The North Pine scheme is a viable scheme but environmental and cost issues relating to the disposal of brine would need to be resolved. The Redlands scheme relies on PRW discharge to the North Stradbroke Island aquifers. Proposals for increased extraction from these aquifers were recently stopped primarily for environmental reasons. Detailed groundwater modelling will need to be undertaken to show that PRW discharge to the aquifers would counteract the impacts of increased extraction. The Wyaralong Dam Scheme is the highest cost scheme on a levelised cost basis. Alternative re-use options for the wastewater treatment plants in the northern Beaudesert area may be more attractive. Such options could include provision of dual reticulation of Class A+ water to new urban areas. Further Investigations Detailed site specific investigations are required to prove the viability of potential schemes identified in this report. Such investigations should include: Determining the management goals for the storage and assessing the water quality targets. This will include a review of any environmental risks associated with changing water quality; Reviewing treatment options to achieve the water quality targets; Assessing risks associated with the proposal and management measures necessary to mitigate risk; Carrying out hydrodynamic and water quality modelling to assess mixing characteristics and water quality changes. Dynamic modelling is recommended to consider a range of operating scenarios; and More detailed engineering analysis and cost estimation to verify the preliminary cost information provided in this report. March 2008 Ref: vii

9 Table of Contents 1 Introduction SEQ WWTP Discharge Quantities Current SEQ WWTP Discharges Contributing Population Projections LGAs Other Than Brisbane City Discharge Growth Projections Pre-drought Per Capita Sewage Flows Estimates of Future WWTP Discharges for other than Brisbane City Future Brisbane City Non-drought Period Adjustments WWTP Discharges Available for Recycling Treatment and Storage Treatment for PRW Planned and Unplanned Use of WWTP Effluents Water Quality Objectives Adopted Water Quality Targets for Environmental Health and Public Benefit, Welfare, Safety and Health Target Water Quality for Potable Use (Product Water) Treatment Options to Produce PRW The Treatment Process Adopted for this Study SEQ Water Supply Dams Aquifer Storages Multiple Barrier Approach and Environmental Buffers WWTPs and Potential Discharge Storages Use of PRW to Supplement Water Supplies in South East Queensland Recycled Water availability Principal Adopted for the Use of Recycled Water Estimates of Recycled Water Use Future Recycled Water Commitments Total water available for PRW use Potential PRW Schemes Mixing Limits for Recycled Water Placement in Storages Dilution Modelling Treated Water Draw-off Rates Modeling Options Modelling Results Interpretation of Results Wivenhoe Dam March 2008 Ref: viii

10 5.3.3 North Pine Dam and Lake Kurwongbah Hinze Dam Baroon Pocket & Ewen Maddock Dams Cooby, Cressbrook and Perseverance Dams Wappa, Cooloolabin and Poona Dams Leslie Harrison Dam Bribie Island Aquifer Lake MacDonald Wyaralong Dam Traveston Crossing Dam Stages 1 and Summary of Modelling Investigations Preferred PRW Options Increases in Dam and Aquifer Yield Recycled Water Scheme Costs Costing Basis AWTP Costs Pipeline Costs Pumping Station Costs All of Life Costs Scheme Costs Exceptions Gold Coast Scheme North Pine Dam Scheme Sunshine Coast Scheme Redland Bay Scheme Wyaralong Dam Scheme Toowoomba Scheme Cost Summary Conclusions...67 References...69 March 2008 Ref: ix

11 1 Introduction A range of purified recycled water (PRW) schemes were identified during preparation of the draft of the South East Queensland Regional Water Supply Strategy (SEQ RWSS) for producing PRW from the existing wastewater treatment plants. One such scheme is the Western Corridor Recycled Water Project (WCRWP). This project is already underway to establish advanced water treatment plant (AWTP) facilities at the Luggage Point, Gibson Island and Bundamba wastewater treatment plants treating water using micro filtration, reverse osmosis and advanced oxidation processes. Stage 1 of these works will provide 66 ML/day recycled water to power stations at Swanbank and Tarong. Stage 2 will provide an additional 166 ML/day that may be available as PRW to be pumped to Wivenhoe Dam for reuse as part of that dam s yield through the Mount Crosby water treatment plant. The wastewater treatment plants (WWTPs) supplying the WCRWP account for about 45% of the total WWTP discharges in SEQ. There are thus a number of other WWTPs in SEQ that have the potential for the production of significant quantities of PRW. The purpose of this study is, therefore, to determine the full potential of these other plants to contribute to the supply of PRW. In particular, the study identifies reuse schemes additional to the WCRWP which could cost effectively maximize the reuse potential. The methodology undertaken in this study is as follows: Review existing data for wastewater treatment plants (WWTPs) in SEQ. Project wastewater flows through to 2051 using a combination of Department of Local Government, Planning, Sport and Recreation population projections, and projections by prepared by the Brisbane City Council. Establish and make deductions for existing and future recycled water demands. For initial screening purposes propose limits for minimum detention time and maximum mixing ratios for PRW in the storages. Establish storage locations and their capacities for holding recycled water based on the rational of detention time and mixing ratios. These locations include both surface and groundwater storages. Determine increased yields to storages achieved by the addition of PRW. Determine ranked implementation and operational costs for potential PRW schemes. Prioritize the development of identified potential PRW schemes. March 2008 Ref:

12 2 SEQ WWTP Discharge Quantities 2.1 Current SEQ WWTP Discharges The sources of recycled water considered for this study are the discharges from the SEQ local government area (LGA) waste water treatment plants. Those plants, and their current loadings, are listed in Table 2-1 below. These current loadings are 2006 average inflows and assume no drought flow reductions. These have generally been sourced from the report, Review of Use of Stormwater and Recycled Water as Alternative Water Resource, or as advised by the controlling LGA. It is noted that sufficient continuous flow records were only available for the Brisbane and Logan flows to allow their adjustment to average dry weather flows (ADWF). Figure 2-1 shows the treatment plant locations. Table 2-1 LGA Wastewater Treatment Plants and Daily Discharges in SEQ (2006) Local Government Area Wastewater Treatment Plant 2006 Loading (kl/day) Beaudesert Beaudesert 1,339 Kooralbyn 255 Jimboomba 200 Canungra 172 Logan Village 25 Boonah Boonah 643 Kalbar 263 Aratula 11 Brisbane Luggage Point 136,000 Oxley Creek 60,000 Gibson Island 43,000 Sandgate 19,300 Wynnum 7,200 Wacol 5,300 Fairfield 2,600 Karana Downs 480 Nudgee Beach 101 Caboolture East Burpengary 7,000 South Caboolture 8,500 Bribie Island 3,500 Woodford 430 Caloundra Kawana 17,000 Caloundra 3,900 Landsborough 1,900 Maleny 665 March 2008 Ref:

13 Local Government Area Wastewater Treatment Plant 2006 Loading (kl/day) Esk Toogoolawah 315 Esk 301 Lowood 301 Fernvale 45 Somerset Dam 16 Gatton Gatton 1,300 Helidon 140 Gold Coast Coombabah 64,542 Merrimac 32,286 Elanora 24,630 Beenleigh 18,339 Ipswich Bundamba 16,400 Goodna 9,200 Carole Park 4,800 Rosewood 310 Kilcoy Kilcoy 350 Laidley Laidley 520 Forest Hill 137 Logan Loganholme 43,000 Maroochy Maroochydore 23,223 Nambour 6,000 Coolum 5,000 Sunshine Coast 3,000 Kenilworth 100 Noosa Noosaville 9,322 Cooroy 1,000 Pine Rivers Murrumba Downs 17,100 Brendale 7,030 Dayboro 150 Redcliffe Redcliffe 13,000 Redlands Capalaba 5,760 Thorneside 8,960 Cleveland 6,640 Victoria Point 5,840 Mt Cotton 361 Point Lookout 243 Toowoomba Wetalla 27,500 March 2008 Ref:

14 Figure 2-1 Treatment Plant Locations March 2008 Ref:

15 2.2 Contributing Population Projections LGAs Other Than Brisbane City The contributing population growth to the WWTPs listed in Table 2-1, other than for Brisbane City, has been estimated through to 2026 using Department of Local Government, Planning, Sport and Recreation (DLG) medium series population projections. Table 2-2 refers. Table 2-2 DLG Population Growth Projections Average Annual Population Change Local Government Area 10 Years to Years to 2026 Beaudesert Boonah Caboolture Caloundra Esk Gatton Gold Coast Ipswich Kilcoy Laidley Logan Maroochy Noosa Pine Rivers Redcliffe Redlands Toowoomba Year 2051 population projections were prepared jointly by the Queensland Water Commission (QWC) and MWH during preparation of the report, Regional Water Needs and Integrated Urban Water Management Opportunities Report. Those values are set out in Table 2-3 along with 2006 and 2026 population values. Growth projections for the period 2026 through to 2051 were determined by linear interpolation. Table 2-3 Year 2006, 2026 and 2051 Populations Local Government Area Year 2006 Population 1 Year 2026 Population 2 Year 2051 Population Beaudesert 64, , ,723 Boonah 9,117 10,125 11,955 Brisbane 992,176 1,164,095 1,457,225 Caboolture 135, , ,203 Caloundra 93, , ,730 March 2008 Ref:

16 Local Government Area Year 2006 Population 1 Year 2026 Population 2 Year 2051 Population Esk 16,035 19,652 24,559 Gatton 16,635 21,967 28,282 Gold Coast 507, , ,403 Ipswich 143, , ,186 Kilcoy 3,641 4,619 5,521 Laidley 15,314 25,069 48,158 Logan 178, , ,416 Maroochy 152, , ,646 Noosa 49,213 58,432 58,891 Pine Rivers 144, , ,295 Redcliffe 52,518 62,673 68,734 Redlands 131, , ,023 Toowoomba 96, , , Source: Australian Bureau of Statistics, Regional Population Growth, Australia, Cat. No Source: PIFU Medium Series, 2006 edition 2.3 Discharge Growth Projections Pre-drought Per Capita Sewage Flows Pre-drought per capita sewage flows were calculated for the SEQ area using the sewage flow data from Table 2-1 and the net contributing 2006 population. The net contributing population was estimated from Table 2-3 less the non-sewered population. The report, Audit of Non-Sewered Areas in South East Queensland, provides estimates of numbers of existing and future on-site sewerage systems for 2003 and 2013 in SEQ. An average household occupancy of 2.51 persons was adopted in accordance with Office of Economic and Statistical Research 2006 data for the Brisbane and Moreton statistical divisions. The resultant non-sewered populations for 2003 and 2013 were estimated to be 122,196 and 179,240. The overall average sewage flow for SEQ was calculated as 271 L/c/d. This flow only marginally reduces to 267 L/c/d if Brisbane City, which contributes about 42% of SEQ sewage, is omitted. For this report s purposes of establishing the potential for the indirect potable reuse of recycled water, an average pre-drought sewage flow rate of 230 L/c/d has been adopted. This is a conservative value which provides a reduction in the sewage flow estimates to allow for: Adjustment for the true dry weather flow from each LGA this is commonly a 5-10% reduction in the average daily sewage flow; Peak wet weather flows which can not be reasonably captured for re-treatment in an AWTP this is also in the order of a further 5 10% of the total inflow to a WWTP ; and March 2008 Ref:

17 The vagaries of seasonal contributing factors such as tourism Estimates of Future WWTP Discharges for other than Brisbane City Estimates of future WWTP discharges for other than Brisbane City WWTPs were estimated by multiplying the population estimates for each LGA as shown in Table 2.2 by 230 L/c/d. Table 2.6 shows the estimated discharges for each LGA Future Brisbane City Non-drought Period Adjustments For Brisbane City, the estimated discharges were provided by Brisbane Water for each of the WWTPs commencing at 2006 and increasing in five year intervals up to An ultimate value was also provided which, for this study s purposes, was assumed to be equivalent to the 2051 projection. Values for years between 2031 and 2051 were determined by linear interpolation. The Brisbane City projections recognize likely future intra-catchment changes. The estimates provided by Brisbane Water have been adjusted to account for the fact that the 2006 discharges were measured during the drought and there is likely to be some recovery following the drought. To estimate the recovery that is likely the estimates have been bench-marked to the 2005 discharges as this is about the time when water consumption was about equal to the 230 L/c/d residential water consumption target that has been adopted by the QWC for the post drought period. An increase of 9.4% has thus been made to the 2006 WWTP discharges to bring them to the equivalent of a post drought discharge. The adjusted flows are shown in Table 2.5. Table 2-5 Brisbane City WWTP Discharge Projections Expected ADWF (ML/d) in Year WWTP Ultimate Luggage Point Oxley Creek Fairfield Gibson Island Wynnum Sandgate Wacol Karana Downs Nudgee Beach Totals WWTP Discharges Available for Recycling Table 2-6 sets out the estimated conservative quantities of water which would be discharged from the SEQ WWTPs. In summary, those estimates are based on: For Brisbane City WWTPs, Brisbane Water estimates as per Table 2-5 with a 9.4% increase. March 2008 Ref:

18 For other than Brisbane City WWTPs, existing WWTP discharges, as per Table 2-1. Future year discharges are estimated by applying the population growth projections from Table 2-2 with a sewage flow rate of 230 L/c/d. Table 2-6 Projected SEQ WWTP Discharge Estimates Year (ML/annum) LGA Beaudesert 727 1,632 2,538 4,609 6,680 9,225 14,314 19,404 Boonah Brisbane 109, , , , , , , ,428 Caboolture 7,092 8,762 10,432 11,917 13,402 13,990 15,164 16,338 Caloundra 8,236 9,843 11,449 12,926 14,403 16,567 20,893 25,220 Esk ,102 Gatton 1,019 1,113 1,208 1,334 1,461 1,567 1,779 1,991 Gold Coast 51,026 56,838 62,650 68,044 73,437 75,970 81,037 86,104 Ipswich 11,209 14,678 18,148 23,112 28,077 31,750 39,095 46,440 Kilcoy Laidley ,133 1,521 2,296 3,071 Logan 15,695 16,354 17,014 17,814 18,614 19,205 20,386 21,568 Maroochy 13,623 15,671 17,720 19,884 22,048 22,438 23,218 23,999 Noosa 3,768 4,024 4,280 4,429 4,579 4,586 4,602 4,617 Pine Rivers 8,862 10,591 12,319 13,380 14,440 15,440 17,442 19,443 Redcliffe 4,745 4,964 5,183 5,348 5,513 5,615 5,818 6,022 Redlands 10,148 11,221 12,293 13,307 14,321 14,360 14,439 14,518 Toowoomba 10,038 10,444 10,850 11,202 11,554 11,891 12,565 13,239 Totals: 256, , , , , , , ,421 March 2008 Ref:

19 3 Treatment and Storage 3.1 Treatment for PRW Planned and Unplanned Use of WWTP Effluents The inclusion of WWTP discharges to the inflow of water treatment plants is undertaken in an unplanned way at numerous locations around the world, including Australia. In some cases the fraction of STP discharge to water treatment plant inflow can be in up to 70% (Thames River, UK). The water treatment processes are in most cases designed to suit the physical and chemical characteristics of the raw water source and little consideration is given to whether the STP discharge is contributing any particular levels of pathogens or other contaminants. Commonly, the water treatment processes would consist of conventional coagulation, sedimentation, filtration and disinfection. Examples of such schemes are the Thames River in London, the Brisbane River in SEQ, and at Penrith on the Hawkesbury-Nepean River near Sydney. In London, up to 70% of the water extracted from the Thames River for potable supplies in dry years is discharged from wastewater treatment plants. The Brisbane River/Somerset Dam/Wivenhoe Dam system receives discharges from the Woodford, Kilcoy, Toogoolwah, Esk, Fernvale and Lowood WWTPs. The Mt Crosby water treatment plant, which treats the water from these dams, is a conventional treatment process incorporating sedimentation and filtration. The wastewater treatment process at Penrith was for many years conventional secondary treatment plant but now includes flocculation, clarification, filtration, granular activated carbon (GAC), chlorination and ph adjustment. However, the planned inclusion of sewage treatment plant discharges to water treatment plant inflows has been undertaken in only a relatively small number of cases. Table 3-1 provides examples of situations where this has been documented and schedules the treatment processes which have been applied. It can be seen from the table that a range of treatment processes have been successfully utilized although the trend in the more recent treatment facilities is towards using membranes. While not documented in the table, it is also noted that there is an emerging growth in the understanding and design of natural processes, in particular wetlands, for improved treatment of effluent from wastewater treatment plants. An example of this is in Clayton County, Georgia, USA. This scheme treats an average of 68 ML/d from the Casey WWTP, a conventional secondary treatment process. About 50% goes to land application and the remainder to a purpose designed wetland. Discharge from the wetlands is to storage reservoirs. Flow from the reservoirs is combined with local creek and spring-fed sources to feed a conventional water treatment plant. During prolonged dry periods the ratio of treated effluent to creek and spring water exceeds 30%. The type of treatment process adopted is particularly relevant to this report because some processes have higher recovery rates, i.e. percentages of water for transferring to storage, than others. Generally, the non-mf/ro type processes outlined in Table 3-1 have recovery rates of 90 to 95 percent depending on the level of sludge dewatering and filtrate return undertaken. MF/RO processes have lower recovery rates in the order of 75 to March 2008 Ref:

20 85%. Recovery rates are dependent on the quality of the feed water and the water quality requirements for the product water and waste stream. This is discussed further in Section 3.5. March 2008 Ref:

21 Table 3-1 Planned Sites Incorporating Sewage Treatment Plant Discharges to Water Treatment Plants Location Application Volume Produced Percent to Potable Supply Treatment Process Montebello Forebay, California Ground water recharge. Max discharge allowed 74,000 ML/yr. Averaged over 3yr <61,674ML/yr. No more than 50% of water delivered to aquifer can consist of reclaimed water. Recycled water makes up to 38% of extracted water. Divert industrial effluents. Activated sludge secondary treatment followed by: Mono and dual media filtration Chlorination Lime treatment. Reclaimed water meets all USA federal drinking water regulations. Orange County, California Ground water recharge. 57,000 ML/day used for recharge. Contributes approx 4% of total replenishment to groundwater basin. Prior to 2006 injected water constitutes no more than 5% of extracted water for potable reuse. By 2007, IPR will supply 25% of extracted water. Secondary treatment followed by: Chemical clarification (lime dosing) and mixing Re-carbonation Multimedia filtration GAC or reverse osmosis Chlorination and blending. Extent of blending depends on whether GAC or RO treated. With RO, ratio of recycled to blended water is increased to 2:1. GRW system to commence in 2007 will provide MF, RO and UV / hydrogen peroxide. Upper Occoquan, Virginia Surface water supplement. 200 ML/day wastewater. Up to 80-90% of inflow to reservoir used to supply drinking water during drought in early 1980 s. Secondary activated sludge treatment followed by: High-lime treatment Clarification 2 Stage recarbonation Sand filtration GAC Ion exchange Chlorination Then discharged to reservoir. Water treatment plant supplying potable water is conventional with PAC, coagulation, flocculation and clarification with chloramines disinfection. March 2008 Ref:

22 Location Application Volume Produced Percent to Potable Supply Treatment Process Singapore Surface water supplement. About 18 ML/day to reservoir. Initially 1% of water consumed for potable purposes. Proposed to increase to 2.5% by Combined volume of potable and industrial using recycled water planned to reach 20% by Receives < 95% WW from domestic sources. Secondary treatment followed by: Membrane filtration (MF or UF) Reverse osmosis UV disinfection Stability control Chlorination. Windhoek, Namibia Surface water supplement. Excess production will be used for aquifer recharge. Produces 21ML/day purified water. Initially the maximum percentage of reclaimed water that was supplied to the distribution network 35%. (Is blended with other water before distribution) This was increased to 50% during 2001 when Namibia was experiencing low rainfall The plant now produces on average about 25-33% of the total potable water demand for Windhoek. Excess reclaimed water will be used to recharge the Windhoek aquifer.. Diverts industrial effluents. Activated sludge WWTP. Mixed with water from dam in a ratio of 1:3.5 and treated before distribution to drinking water standards through: Pre-ozonation Dissolved air floatation Rapid sand filtration Ozonation GAC filtration and adsorption Ultra filtration Chlorination. Essex, UK Surface water supplement. Up to 35 ML/d of recycled water discharged to river for water treatment downstream. Normally 7.4% with maximum of 32.7% in WWTP process primary sedimentation, trickling filters and activated sludge, and UV disinfection. Is pumped to storage (214 days minimum detention time). The water treatment process includes: Pre-ozonation Coagulation Sedimentation Lime softening Rapid sand filtration Ozonation GAC filtration Chlorination. March 2008 Ref:

23 3.1.2 Water Quality Objectives In order to assess the water quality objectives for the water entering the water storages reference needs to be made to the ANZECC and ARMCANZ (2000) Australian and New Zealand Guidelines for Fresh and Marine Water Quality (AWQG, 2000). These guidelines suggest the following steps for establishing the water quality objectives: Define the primary management aims; Determine the appropriate Trigger Values for selected indicators; and Apply the Trigger Values using (risk-based) Decision Trees or Guideline packages. Primary Management Aims For each water storage and waterway affected by the addition of PRW, the management aims would need to be determined by consideration of the following: The environmental values to be protected; The level of protection to be provided; Identifying environmental concerns (e.g. toxic effects, nuisance aquatic plant growth, effects of changes in salinity or temperature); and Determining the management goals. The management goals are normally defined in terms of measurable indicators such as toxicant concentrations or concentrations or loads of physical or chemical stressors. The identification of the management goals for the various water storages and downstream, waterways being considered are beyond the scope of this investigation, however, it is recommended that this be done should the investigation proceed further. Guideline Trigger Value Once the management goals have been selected, it is necessary to select appropriate indicators and then determine the appropriate Trigger Values for those indicators. For physical and chemical stressors and toxicants the preferred approach to deriving trigger values follows the order: Use of biological effects data; Then local reference data (mainly physical and chemical stressors); and Finally (least preferred), the tables of default values provided in the AWQG. The preferred method of establishing trigger values is to derive data from the same (undisturbed) ecosystem. As the reference systems are most likely disturbed an appropriate percentile of the reference data distribution can be used. As noted previously the determination of management goals (and Trigger Values) is beyond the scope of this investigation. Such investigations would need to be carried out for each water storage and waterway affected by the addition of PRW. In the absence of March 2008 Ref:

24 outputs of such an investigation some preliminary discussion on Trigger Values is provided in the following section. 3.2 Adopted Water Quality Targets for Environmental Health and Public Benefit, Welfare, Safety and Health For the water storages being considered the environmental values are likely to include: Aquatic ecosystems; Drinking water; and Recreation and aesthetics. The level of protection that would be required is that there will be no significant change to the water quality as a result of the addition of PRW. Environmental concerns are possibly: Possible adverse effects on aquatic life due to changes in temperature and/or salinity; Nuisance aquatic plant growth due to algal blooms; and Toxic effects due to Cyanophyta outbreaks; Indicative Trigger Values for these environmental concerns in the first instance can be determined by reference to the default trigger values provided in the AWQG. Temperature For temperature no Default Trigger Values are provided in the AWQG. Temperature closely regulates ecosystem functioning both directly, for example by influencing primary production, and indirectly, for example by loss of biota as a consequence of loss of habitat. There is limited information available about thermal tolerances of Australian aquatic organisms or their responses to temperature changes. The Guidelines recommend that ecological studies be carried out and provide guidance as to how such studies be undertaken. This work is outside the scope of this study however for the purpose of this study it has been assumed that the water temperature target is the ambient water temperature in the storage and that any temperature changes can be ameliorated by the incorporation of a diffuser, a cooling pond or wetland system (used for cooling purposes). It is noted that the temperature of the wastewater discharges will be generally higher than the ambient water temperature in the water storages. Salinity For salinity the Default Trigger Values provide a broad range for salinity. The estimation of salinity changes due to PRW addition has not been assessed for this study but the salinity of the PRW is likely to be less than 100 mg/l and this will be less than the typical salinity concentrations found in streams in South East Queensland of between 250 and 550 mg/l. Whilst no adverse biological impacts are anticipated further investigation into the impacts of changing salinity on the aquatic ecosystem is recommended. March 2008 Ref:

25 Nutrients Nutrients encourage the growth of algae and Cyanophyta (blue-green algae). Some species of Cyanophyta produce toxins under some conditions. Some alga species can also cause taste and odour problems. In addition water with high algal cell counts can be difficult to treat using conventional treatment as the algae can block the filters reducing the output from the treatment plant. As noted previously, algal toxins can be produced under some circumstances, as well as taste and odour problems. Additional treatment using powdered activated carbon or ozone and granular activated carbon filtration may be required in some circumstances. Growths of toxic blue green algae can occur when the concentrations of nutrients, nitrogen and phosphorus are low, but blooms are more frequent when the concentrations are high. The introduction of large volumes of recycled water into water storages with elevated levels of nutrients could increase the frequency of blue-green algae blooms and this would be undesirable. The total concentration of nutrients, nitrogen (N) and phosphorus (P), in the water column are useful measures of the potential for nuisance growth plants but they often overestimate what is actually bio-available for plant growth. The most common forms of N available for plant growth are inorganic forms such as nitrate (NO 3), nitrite (NO 2) and ammonia (NH 4+) and organic forms such as urea. NO 3 is the most commonly available and NH 4 is the most readily assimilated by plants. Phosphorus exists in both dissolved and particulate forms. Particulate P includes P bound in organic compounds such as proteins, and P adsorbed to suspended particulate matter such as clays and detritus. Dissolved P includes inorganic orthophosphate, polyphosphates, organic colloids and low molecular weight phosphate esters. Plants can derive their nutrients from sources other than in the water column as there may be significant stores of nutrients in the sediments and associated suspended particulate matter. The intercellular ratio of C:H:O:N:P:S in algae and cyanobacteria approximates 106:263:110:16:1:0.7 and the uptake of nutrients by growing populations also approximate the same ratio often known as the Redfield ratio (Redfield 1958). The TN:TP ratio is often used to evaluate the nutrient status of a water body. When the N:P atomic ratio is greater than 16 then the waterway is said to be P deficient and when it is less than 16 molar or 7 gravimetric, N deficient. N deficient water bodies favour the growth of nitrogen fixing Cyanophyta. The TN:TP ratios, can be misleading as the nutrient forms included in the analysis of total amounts are not all available to algae. Table 3-2 shows the factors determining algal composition (Lawrence, January 2000). Table 3-2 Summary of Factors Determining Algal Composition Nutrient environment Mixing conditions in the surface mixed layer High Moderate Low High Si, High P, High N Diatoms (high biomass) Greens (high biomass) Blue-greens Low Si, Low P, Limiting N Diatoms (low biomass) Greens (low biomass) Blue-greens It has also been shown that species composition of dominant Cyanophyta may be manipulated by changing the dominant form of dissolved inorganic nitrogen (DIN) in the March 2008 Ref:

26 system (Lawrence, January 2000). Small-celled, non N-fixing Cyanophyta (Microcystis) appear to be favoured in the presence of high levels of ammonia, whereas N-fixing Cyanophyta (Anabaena, Aphanizomenon) are favoured in low concentrations of nitrate. In addition when nitrogen is limiting but present as nitrate, green algae appear to have an advantage, but when nitrogen is limiting in the surface waters but present as ammonia in the deeper anoxic zones then colonial Cyanophyta like Microcystis can dominate. If good water quality conditions are to prevail in the water storages following the addition of recycled water it will be important that conditions favouring Cyanophyta are not by induced by the addition of recycled water to the reservoir. Conditions may change depending on the storage level as increased depth will be more favourable to the development of anoxic conditions at the lower depths and this may adversely impact on the water quality. Whilst considerably more work needs to be done in regard to establishing water quality targets for the water storages, it is concluded that it will advantageous to ensure that reservoir mixing is included as part of the water quality management strategy and that nitrate levels are not set too low such that nitrate does not become the limiting nutrient. For nuisance aquatic plant growth and toxic effects due to Cyanophyta outbreaks the management goal will be to maintain nutrient levels at about the same level as exists in the existing water storages. This is the approach adopted for the Western Corridor AWTPs. For these plants the nutrient limits were originally set at the background levels in the Wivenhoe Dam which are TN 0.81 mg/l and TP 0.13 mg/l. Whilst this has been subsequently reviewed taking account the concentration of nutrients in the feedwater (effluent from the WWTPs) and the capability of the AWTPs to remove these nutrients for these conditions, the original criteria have been adopted for this study. This has been done on the basis that the design of any future AWTPs will be able to take advantage of performance modifications to WWTPs to optimize the AWTP performance. 3.3 Target Water Quality for Potable Use (Product Water) Phase 2 of the Australian Guidelines for Water Recycling provides guidance on managing the health and environmental risks associated with potable water recycling schemes. This Guideline should be adopted for the use of PRW for potable purposes. The concepts proposed for the AWTPs proposed in this study would meet the requirements of this Guideline. In addition to the Australian Guidelines for Water Recycling, there are numerous other documents which outline standards and principles that any indirect potable recycling scheme would be required to meet as a minimum. Some important additional documents include: A Guide to Hazard Identification and Risk Assessment for Drinking-water Supplies (Cooperative Research Centre for Water Quality and Treatment (CRCWQT), 2004) developed in support of the Australian Drinking Water Guidelines new focus on risk assessment and management (National Water Quality Management Strategy, 2004); Health Impact Assessment Guidelines (enhealth Council, 2001); March 2008 Ref:

27 Environmental Health Risk Assessment: Guidelines For Assessing Human Health Risks From Environmental Hazards (enhealth Council, 2002); and Australian Drinking Water Guidelines (National Water Quality Management Strategy, 2004). While the ADWG include a range of notionally tolerable contaminant concentration limits by which potable water can be assessed, others guidelines introduce additional aspects of water management best practice. For example, the CRCWQT guidelines introduce the importance of generic advice on risk assessment for potable water supplies. The enhealth Council guidelines provide frameworks for how risk should be assessed in general terms and details on how the technical assessment process might be carried out. These guidelines also provide a reference set of criteria for assessing the strengths and limitations of risk studies undertaken for potable water reuse examples in the literature and for any future projects in Australia. They describe current best practices in terms of Australian regulations, which are fully consistent with the recommendations of the US National Research Council 1998 (NRC, 1998) report. For example, the risk assessment steps in the 1998 NRC report are identical to the ten generic risk assessment activities provided in the enhealth Council guidelines and provides a check list which stakeholders may use to assess whether risk assessments for planned schemes have been adequately undertaken. Phase 2 of the Australian Guidelines for Water Recycling also includes a management framework for the use of the recycled water for indirect potable use. Such a management framework would need to be established for each system using PRW for potable purposes. 3.4 Treatment Options to Produce PRW There are a range of possible treatment options available to produce PRW. Such options include dual membrane processes similar to that used for the Western Corridor Recycled Water Project AWTPs (i.e. membrane filtration and reverse osmosis). Other processes include processes similar to that used by at the South Caboolture Water Reclamation Plant. This plant utilizes de-nitrification, dissolved air flotation and filtration, ozonation and filtration using biologically activated carbon filters and then disinfection. Other processes may include high-lime treatment, clarification, and re-carbonation, multi-media filtration, granular activated carbon filtration, ion exchange and disinfection. As discussed previously the selection of appropriate treatment processes requires consideration of both the suitability of the water produced for potable use and the suitability of the water for discharge into storages or waterways. One of the critical process requirements is the reduction of nutrients (particularly N and P) to acceptable levels. Another critical factor is the salinity of the product water and the impact on the aquatic ecosystem and the water supply system resulting from the recycling process. Different AWTP processes perform differently in this regard. For nutrient removal biological wastewater treatment processes can be very effective in the removal of biodegradable nitrogen (ammonia and nitrate) from sewage. It is an March 2008 Ref:

28 advantage to remove nutrients at the wastewater plant prior to the AWTP. However, there is a non-readily biodegradable nitrogen component which is not removed by biological processes and which can be, in some cases, in excess of 2 mg/l. Removal of this non-readily biodegradable component is not easy using conventional AWTP processes. Reverse osmosis however will remove about 80% of the TN but removal efficiency is very much dependent on the form of nitrogen. The target TN limits set for the Western Corridor Recycled Water Project can be achieved using reverse osmosis with suitable pre-treatment. Technologies that do not utilize reverse osmosis will require a different approach to achieve TN limits set for the Western Corridor AWTPs. At the South Caboolture Water Reclamation Plant, a Moving Bed Bioreactor process is used to reduce the biodegradable component of the nitrogen and there is some further reduction using ozone and biologically activated carbon filters. This plant does not currently meet the lower TN limit of 0.8 mg/l, but it may be possible to achieve the lower limit by modify the plant by some process modifications to both the wastewater treatment plant and the water reclamation plant. This would require further investigation. Removal of phosphorus to low levels is commonly achieved by dosing with aluminium sulphate or ferric chloride, and filtering out the phosphate precipitate. Total phosphorus values of less than 0.05 mg/l are achievable. An example of this is the South Caboolture Reclamation Plant where total phosphorus values are consistently equal to, or less than, 0.05 mg/l. In regard to salinity it is noted that MF/RO/AO treatment process adopted for the WCRWP will produce water with a Total Dissolved Salts (TDS) of about mg/l which is significantly less than the TDS of the water in the Wivenhoe Dam which is of the order of 250 mg/l. With the addition of recycled water the TDS will reduce, the extent of the reduction being dependent on the storage level and the percentage of recycled water added in relation to the total volume. Generally a reduction in salinity is unlikely to prove problematic but further investigation is recommended considering a range of operating scenarios. For other treatment options such as ozone/bac the salinity of the treated water will be similar to the salinity of the WWTP discharges. The TDS for WWTP discharges is likely to be in the range mg/l. This TDS will increase as the water recirculates back through the system. The extent of the increase (or decrease) will vary with time according to storage level and freshwater inputs from surface flows but maximum increases could be significant. Salinity increases may become unacceptable for this treatment option. Further investigation of the impact of the impact of changing TDS is recommended should this treatment option be considered further. Further to the above comments it will be important to consider the impact on consumers of changing salinity due to the addition of recycled water of different salinity to the surface water in the dams, as experience has shown that customers are likely to be more sensitive to rapidly changing salinity than to the absolute value. March 2008 Ref:

29 3.5 The Treatment Process Adopted for this Study Section has established that there are AWTPs elsewhere producing recycled water for transfer to storages for further treatment as potable water. Some of those plants use reverse osmosis, others use processes such as high lime and ozone GAC. Section 3.4 has outlined the nutrient reduction requirements for the control of blue-green algae. Reverse osmosis can be used to reduce both nitrogen and phosphorus levels to the required concentrations. Other AWTP processes have demonstrated an ability to reduce phosphorus to those levels, and it is expected that they are also capable of achieving the required nitrogen levels. However, for this report s purposes it is assumed that all significant recycled water feeds to surface water storages will be treated at an AWTP using a MF/RO/AO process. The basic treatments associated with that process are shown in the process schematic on Figure 3-1. Source: Western Corridor Recycled Water Project Business Case Figure 3-1 Advanced Water Treatment Plant Schematic Further information on the proposed processes is provided following: Chemical Phosphorus Removal The need for additional chemical phosphorus removal will depend on the WWTP effluent TP concentration, the overall recovery required for the plant and the target TP for the AWTP product water. Phosphorus can cause scaling on the membranes and TPs of 1-2 mg/l should be targeted to minimize scaling on the membranes. Lower TP targets are required for higher recoveries. It is preferable to remove TP and TN in the WWTP rather than the AWTP however under some circumstances this may not be possible. If additional phosphorus removal is required prior to membrane treatment this could be achieved by chemical mixing, flocculation, and clarification with provision for collection, thickening and removal of excess sludge. March 2008 Ref:

30 Chloramination Aqueous ammonia and sodium hypochlorite would be dosed upstream of the MF system to limit biological activity and to protect the microfiltration and RO membranes. Microfiltration System The MF system would pre-treat the RO feed water and also provide a barrier to microbial material and will remove helminths, protozoa, bacteria and some viruses. RO System The RO system would remove a large proportion of the dissolved materials in the water including any residual bacteria and viruses in the product water from the MF system. Advanced Oxidation System The advanced oxidation system provides a final disinfection step but also provides a treatment step for removal of some persistent low molecular weight organics (e.g. N nitrosodimethylamine (NDMA) and 1.4 dioxane). RO Concentrate Discharge The RO concentrate is saline and may need further treatment before disposal. Treatment can be complex if disposal to the ocean or an estuary is not possible Other treatment processes might need to be added depending on the level of treatment provided by the WWTP but the preferred approach would be to optimize the performance of the WWTP and the AWTP working together as it is generally more efficient and economical to maximize removal of nutrients through the WWTP processes rather than to provide additional treatment steps in the AWTP. In this respect design of the WWTP to provide for enhanced phosphorus removal would be beneficial to the AWTP. If this is not possible the addition of ferric chloride for the chemical removal of phosphorus upstream of the AWTP may be necessary depending on the recovery required from the AWTP and the TP of the WWTP effluent. It is noted that the recovery required from the AWTP will determine the minimal acceptable TP for the feed water to prevent fouling. For example for a recovery of 85% the feed water TP should not exceed 1 mg/l. For a lower recovery the feed water TP can be higher. A similar comment applies to nitrogen removal. By utilizing the WWTP to remove as much nitrogen and phosphorus as possible the solids handling requirements for the AWTP can be minimized. In addition the WWTP will already have solids handling capability and can normally handle some additional loading without the need for upgrade but some upgrading may be necessary. The chemical nature of the effluent being fed to the AWTP can also have a significant impact. Some effluents have concentrations of elements that can cause potential scaling. Elements of concern include calcium, phosphorus, iron manganese and aluminium, which can cause scaling within the RO membranes. Scaling can often be controlled with ph correction and anti-scalant chemicals, but there is commonly a reduction in the safe recovery rate from the RO system. Higher recovery rates can be achieved by increasing March 2008 Ref:

31 the number of stages within the RO system but this carries associated higher capital and operating costs, and also higher risks of membrane scaling. These risks are significant because in some cases the scaling would be permanent, i.e. the membranes could not be functionally recovered and would need to be replaced. The percentage recovery from a MF/RO/AO system in an AWTP would commonly range from 75% to 85% with the higher value being associated with multiple stages within the RO system. There are both additional capital and operating costs associated with higher recovery system, but such a system can be operated at lower recoveries (and costs) if there is a lower demand. The current design brief for the Luggage Point, Bundamba and Gibson Island AWTPs require a minimum recovery of 82%. For this report s purposes it has been assumed, unless stated elsewhere, that an average 82% recovery will be achieved at all plants. The establishment of an AWTP is not significantly limited by the size of the WWTP. While there are economies of scale associated with such treatment processes, all of the required process elements can be assembled as operational units with outputs of much less than 1 L/s. Whilst it is most important to ensure that the AWTP is properly operated, the lack of local people with suitable experience need not be an impediment as operators can be up-skilled with proper training and technical or operational support can be sourced from a number of private companies SEQ Water Supply Dams Table 3-3 lists the dams in SEQ which currently supply water treatment plants. Also listed are the future Wyaralong and Traveston Crossing Dams which are likely to be constructed over the next decade. Figure 2-1 shows the locations of these dams. Table 3-3 SEQ Water Supply Dams Dam 3 LOS Yield 1 (ML/annum) Full Storage Volume (ML) Surface Area When Full 4 (Ha) Evaporation /Seepage Rate 4 (mm/annum) North Pine Dam 35, ,000 2,180 1,747 Lake Kurwongbah 4,400 15, ,747 Wivenhoe 1,165,200 10,750 1, ,300 Somerset 379,850 4,212 1,747 Baroon Pocket 33,000 61, ,640 Ewen Maddock 2,500 16, ,640 Hinze (raised) 58, ,000 1,473 1,616 Wappa, Cooloolabin and Poona 7, , ,640 Cooby 21, ,785 Cressbrook 9,000 81, ,680 Perseverance 30, ,680 Lake MacDonald 3,500 8, ,640 March 2008 Ref:

32 Dam 3 LOS Yield 1 (ML/annum) Full Storage Volume (ML) Surface Area When Full 4 (Ha) Evaporation /Seepage Rate 4 (mm/annum) Leslie Harrison 5,300 24, ,678 Wyaralong 29, ,000 1,782 1,678 Traveston Crossing (Stage 1) 70, ,400 3,039 1,640 Traveston Crossing (Stage 2) 40, ,900 7,135 1,640 Notes: 1. Level of service (LOS) yields. 2. Combined yield for total South Maroochy system. 3. Weirs at Caboolture and Woodford have not been included because of their small capacities. 4. Source: DNR. Surface area of South Maroochy system dams has been estimated. 5. Combined yield for Hinze and Little Nerang Dams. 6. Preliminary yield, yet to be confirmed. 7. Combined yield for Wyaralong Dam, Bromelton Offstream Storage and Cedar Grove Weir Aquifer Storages The Brisbane aquifer project has to date included the construction of more than 100 investigation bores and 31 production bores to supply in the order of 21 ML/d of groundwater from six main borefields. The Bribie Island aquifer project will include the construction and commissioning of 16 production bores tapping a sand aquifer in the central northern section of Bribie Island together with the construction of approximately five additional production bores to allow for a replacement of an existing main groundwater extraction trench. The target production rates for these bores range from 2.3 to 4.6 L/s, i.e. a total of about 5 ML/d. The net yield including existing bores will be about 6 to 7 ML/d. The potential for aquifer recharge to these areas is unknown. An optimistic estimate might be to, say, double the rain-fed yield storage capacity. In addition to the aquifers discussed above, the Lockyer, Warrill and Bremer valleys to the west of Brisbane are major aquifer storage areas. The Lockyer valley groundwater system, prior to being over extracted, had a yield of 48,000 ML/annum. It would be feasible to re-establish that aquifer with PRW to provide for agricultural irrigation when surface water is otherwise unavailable. 3.6 Multiple Barrier Approach and Environmental Buffers The multiple barrier approach to supply of PRW is fundamental for ensuring the supply of high quality water to customers. As sewage contains contaminants such as microbial pathogens at levels far greater than those commonly found in rivers or reservoirs, the need for highly reliable barriers is much more significant. No single barrier is effective against all conceivable hazards or is completely effective all of the time. Multiple barriers protect against variations in performance of individual barriers. There are no hard and fast rules as to how many barriers and what sort of barriers should be provided, but most AWTPs incorporate a range of treatment processes whereby March 2008 Ref:

33 individual process units partially duplicate treatment effectiveness of other process units so that there is multiple treatment barriers for most parameters. In addition there is a view by some that environmental buffers should be incorporated as one of the barriers in any project supplying PRW for municipal use. The Water Services Association of Australia, for example, states that the use of environmental buffers represents world s best practice. It further states that the presence of environmental buffers is supported by most communities which have made the decision to supplement their supplies with recycled water. It should be noted also that there are others who dispute the need for environmental buffers. For this study it is assumed that environmental buffers will be provided. Environmental buffers could be a water storage, an aquifer or a wetland system. The potential benefits of such a buffer are: Increased community acceptance of the concept as research shows that contact with natural processes increases confidence in the water quality; Increased time for identification of any anomalies in the water quality; Provision of an additional treatment barrier for pathogens and problematic compounds such as endocrine disrupting compounds. There are also some disadvantages as the purified water may be degraded by the inferior water quality in the storage. There may also some additional evaporation losses although these are likely to be low as the evaporation would have been occurring regardless of whether PRW was added to the storage or not. The increased evaporation would result from a slightly increased surface area. Environmental buffers are mandated in some USA guidelines and are recommended by some industry groups such as the Water Services Association of Australia, as noted previously. It is QWC Policy that a multiple barrier approach be taken for the use of PRW. Figure 3-2 illustrates the multiple barriers adopted by the QWC for the PRW process. March 2008 Ref:

34 Source: QWC Figure 3-2 The Multiple Barrier Approach The dam and aquifer storages are expected to provide a barrier where natural processes can come into play, i.e. to provide an environmental buffer. AWTPs are designed to achieve specific performance outcomes but there are hard and fast rules for designing environmental buffers. The WSAA Position Paper No. 2 Refilling the Glass states that an environmental buffer may consist of a water supply reservoir or a soil-aquifer system to which recycled water is added. AWTPs are designed to remove contaminants of concern to concentrations which are considered to be acceptable for potable use. Environmental buffers such as water storages or aquifers thus provide some additional unquantifiable treatment efficacy. Selection of appropriate design criteria is thus somewhat arbitrary. For this reason reference has been made to the practices adopted by other water authorities and indicative criteria selected. Further evaluation of these criteria is strongly recommended should the proposals proceed further. Some indicative maximum percentages of recycled water added to water storages or aquifers are shown below: Singapore (surface water) 1% - Proposed to increase to 20% Orange County (aquifer water) < 5% - Proposed to increase to 25% Montebello Bay (aquifer water) 38% March 2008 Ref:

35 Thames River (surface water) < 70% Clayton County (surface water) > 30% Windhoek (surface water) < 50% Essex (surface water) < 33% The draft criteria proposed by the California Department of Health Services (DHS), California Code Regulations, Title 22, for aquifer discharge, limits the maximum content of recycled water in a potable water well to 50% and requires a retention time in the aquifer of between 6 and 12 months. In regard to detention times the main advantage of environmental buffers is to provide the opportunity for die-off or degradation of any residual pathogens and chemicals such as endocrine disrupting compounds. Typically the survival time of viruses in freshwater is less than 120 days (Feachem et al, 1983). On the other hand, the half life of endocrine disrupting compounds is variable and some compounds can considerably exceed 100 days. Degradation of endocrine disrupting compounds can occur as a result of biodegradation, photolysis, volatilisation or adsorption onto particles and settlement. Unfortunately, the mixing percentage and detention time values, as adopted elsewhere, show no commonality to give guidance for the operation of SEQ s storages. It is believed that of the two criteria, minimum detention time has the greater rational basis. Nevertheless for this study both mixing ratio (measured as a percentage) and detention time have been considered with the proviso that the option should be able to meet this criterion for at least two years of operation. A lesser period was considered to be too short for the capital investment involved. For the preliminary assessment of options and the culling of options that were considered to be sub-optimal, the following criterion was adopted: The system should be able to operate for at least two years whilst limiting the percentage of PRW in the storage to the mid range of what has been used elsewhere and maintaining a reasonably long detention period for the PRW in the storage. A reasonably long detention period was assumed to be 12 months; and The percentage of PRW in the storage that was considered mid range was 40%. It is acknowledged that these figures may be conservative but they will provide a basis for this preliminary assessment. Considerable refinement may be possible with more detailed investigation. 3.7 WWTPs and Potential Discharge Storages Table 3-4, provides a summary of each WWTP, the nature of its discharge in terms of quantity and proximity to a potential storage, and the realistic storage option available. March 2008 Ref:

36 Table 3-4 SEQ WWTPs and Potential Discharge Receival Storages Local Government Area Beaudesert Wastewater Treatment Plant Beaudesert Kooralbyn Jimboomba Canungra Logan Village Boonah Kalbar Aratula Proposed Discharge Strategy and Storage The total discharge is currently 1.3 ML/d of which the majority is directed to irrigation. Excess discharge is to a tributary of the Logan River approximately 15 km upstream of the proposed Cedar Grove Weir. Consideration will need to be given to additional treatment to cope with wet weather bypassing to the Logan River. This discharge is minor and will likely only contribute intermittently and won t be considered as a dam recycled water source for this report s purposes. The total discharge is currently 0.2 ML/d of which the majority is directed to irrigation. Any excess discharge is to a tributary of the Logan River approximately 30 km upstream of the new Cedar Grove Weir. Consideration will need to be given to additional treatment to cope with wet weather bypassing by passing to the Logan River. This discharge is minor and will likely only contribute intermittently and won t be considered as a dam recycled water source for this report s purposes. Any excess discharge is to the Logan River downstream of the new Cedar Grove Weir. It is possible that this discharge will ultimately be collected and transferred to the proposed Wyaralong Dam. The Mt Lindesay/North Beaudesert Study area report suggests that up to seven WWTPs will be provided in the future Beaudesert growth area. Discharge from those WWTPs could be treated at a single AWTP and stored in Wyaralong Dam. The total discharge is currently 0.2 ML/d of which the majority is directed to local agricultural irrigation. Excess discharge is to Canungra Creek. Portion of this discharge will be collected as part of the Hinze Dam water harvesting from Canungra Creek and the adjacent Coomera River. Nevertheless, this discharge is minor and will likely only contribute intermittently, and won t be considered as a dam recycled water source for this report s purposes. This plant does not have a water course discharge. Any excess discharge would be to the Logan River. This is unlikely to change within the report study period. This is a minor plant and its discharge will not be captured. The total discharge is currently 0.9 ML/d and is estimated to increase to about 1.4 ML/d by Excess discharge is to Teviot Brook approximately 5 km upstream of the southern extent of the proposed Wyaralong Dam impoundment area. Consideration will need to be given to additional treatment. This discharge is minor and will likely only contribute intermittently, and won t be considered as a dam recycled water source for this report s purposes. The total discharge is currently 0.3 ML/d of which the majority is directed to irrigation. Excess discharge is to Warrill Creek and ultimately the Bremer River. This discharge is minor and will likely only contribute intermittently, and won t be considered as a dam recycled water source for this report s purposes. The total discharge of this minor plant is about 11 KL/d. This is a minor plant and its discharge will likely not be captured. Brisbane Luggage Point Luggage Point WWTP is projected to discharge about 176 ML/d by 2026 and 190 ML/d by It is currently proposed to treat 66 ML/d of that discharge to a PRW standard to be transferred for power station cooling water and/or discharge to Wivenhoe Dam. A further 14 ML/d is already recovered in a separate MF/RO process and sent to the BP refinery. Allowing for a MF/RO recovery factor at the Luggage Point AWTP, there could be a net surplus of about 76 ML/d of WWTP discharge in 2026 and 90 ML/d in Surplus from the Luggage Point WWTP will likely initially be sent to the Gibson Island AWTP. North Pine Dam could also be a future receiving storage. March 2008 Ref:

37 Local Government Area Brisbane Wastewater Treatment Plant Oxley Creek Proposed Discharge Strategy and Storage Oxley Creek WWTP is projected to discharge about 85 ML/d by A pipeline connection is being built to the Bundamba AWTP to transfer that discharge for conversion to PRW. To be used for power station cooling water and/or discharge to Wivenhoe Dam. Gibson Island Gibson Island WWTP is projected to discharge about 60 ML/d by An AWTP is currently being constructed at Gibson Island to produce 66 ML/d of AWTP. It is likely that plant s capacity will be increased to 100 ML/d..That plant s PRW will be transferred for power station cooling water and/or discharge to Wivenhoe Dam. Sandgate Wynnum Wacol Sandgate WWTP is projected to discharge about 26 ML/d by Both North Pine and Wivenhoe/Somerset Dams are options as receiving storages. Wynnum WWTP is projected to discharge about 8 ML/d by It is proposed to treat that discharge by MF/RO and transfer near to all of the plant s discharge to the nearby Caltex refinery. Wacol WWTP is projected to discharge about 7 ML/d by A pipeline connection is being built to transfer the effluent to the Bundamba AWTP for conversion to PRW. Fairfield Fairfield WWTP is projected to discharge about 3 ML/d by Wivenhoe/Somerset Dam via the Western Corridor pipeline is the most likely option as a receiving storage. Karana Downs Karana Downs WWTP is projected to discharge about 0.7 ML/d by While Wivenhoe/Somerset Dam via the Western Corridor pipeline is a possible receiving storage, the small rate of discharge is unlikely to allow this to be an economic option. Caboolture Caloundra Nudgee Beach East Burpengary South Caboolture Bribie Island Woodford Kawana Caloundra Landsborough Nudgee Beach WWTP is projected to discharge about 0.1 ML/d through to Both North Pine and Wivenhoe/Somerset Dams are possible storage options but the small rate of discharge is unlikely to allow this to be an economic option. The discharges from both the South Caboolture and East Burpengary WWTPs discharge into Deception Bay. The 2051 flow is projected to be over 36 ML/d. The closest PRW receiving storage would be North Pine. Wivenhoe/Somerset Dam would be an alternative is North Pine Dam is unsuitable. The projected 2051 discharge from the Bribie Island WWTP is 7.3 ML/d. Discharge is currently to aquifer. The closest PRW receiving storage would be the Bribie Island aquifer. The Woodford WWTP currently discharges about 0.3 ML/d to the Stanley River approximately 15 km above the impoundment area of Somerset Dam. The Kawana WWTP discharges via ocean outfall. Its closest PRW receiving dams would be Ewen Maddock. The upper reaches of the Stanley River (flowing to Somerset Dam) would be the next closest discharge point, but Woodford s WTP would draw from a weir approximately 20 km downstream. Alternatively, discharge points would be to Baroon Pocket Dam or the future Traveston Crossing Dam. The Caloundra WWTP until recently discharged to the ocean. Its catchment has now been diverted to the Kawana WWTP. Landsborough WWTP currently produces about 1.9 ML/d which is pumped to the Kawana ocean outfall. Ewen Maddock Dam would be its closest receiving storage. March 2008 Ref:

38 Local Government Area Wastewater Treatment Plant Proposed Discharge Strategy and Storage Caloundra Maleny The Maleny WWTP currently discharges about 0.7 ML/d of which the majority goes to irrigation. Excess discharge is to Obi Obi Creek and Baroon Pocket Dam approximately 5km downstream. There have been previous algal problems associated with this discharge and consideration might need to be given to the provision of additional treatment as part of the Traveston Crossing Dam development. This discharge is minor and will likely only contribute intermittently, and won t be considered as a dam recycled water source for this report s purposes. Esk Gatton Gold Coast Ipswich Esk Lowood Fernvale Somerset Dam Toogoolawah Gatton Helidon Coombabah Merrimac Elanora Beenleigh Bundamba Goodna Carole Park Rosewood The current discharges from the Esk, Lowood and Fernvale WWTPs are less than 0.7 ML/d. Excess discharge is to the Wivenhoe Dam. However, 2051 discharge projections increase to about 2.3 ML/d and consideration might need to be given in the future to the provision of additional treatment. The major growth area will be Lowood. Discharge from Lowood and Fernvale is currently into the Brisbane River downstream of Wivenhoe Dam. Esk SC is currently undertaking a review of the standard of treatment to those plants. One solution would be to transfer the treated effluent to the Bundamba AWTP in the same manner as is proposed for the Oxley Creek WWTP. The Esk WWTP discharge is now directed to Wivenhoe Dam and is included in that dam s recycled water inflow. Somerset Dam township is primarily a septic tank system. Discharges are minor and drain into the upper reaches of Wivenhoe Dam. The total discharge is currently 0.2 ML/d. Any excess discharge is directed to Cressbrook Creek and flows into the upper reaches of Wivenhoe dam. The total projected 2051 discharge of the Gatton and Helidon WWTPs is about 2 ML/d of which the majority is directed to irrigation. Excess discharge is to Lockyer Creek and ultimately the Bremer River. Draw-off from the Bremer to the Mt Crosby WTP will be implemented when the Swanbank power station is provided with recycled water for cooling purposes. These discharges are minor and will likely only contribute intermittently, and won t be considered as a dam recycled water source for this report s purposes. The total net projected 2051 discharge for the four Gold Coast WWTPs is 236 ML/d. Discharge is to the ocean. Hinze Dam is the only receival option for the Coombabah, Merrimac and Elanora plants. Beenleigh s discharge could be directed to any of the Wivenhoe, Hinze or future Wyaralong Dams. The total net projected 2051 discharge for the four Ipswich WWTPs is 127 ML/d. Discharge is currently to Bremer and Brisbane Rivers. The Wivenhoe/Somerset Dam is the only receival storage option for the Ipswich WWTPs. Kilcoy Kilcoy The total projected 2051 discharge of the Kilcoy WWTP is about 0.8 ML/d. Excess discharge is to Somerset Dam. This discharge is minor and will likely only contribute intermittently, and won t be considered as a dam recycled water source for this report s purposes. Laidley Laidley Forest Hill The current discharges from the Laidley and Forest Hill WWTPs are less than 0.7 ML/d. Excess discharge is to Lockyer Creek and ultimately the Bremer River. However, 2051 discharge projections increase to about 8 ML/d and consideration will need to be given to the provision of additional treatment to the discharge. This discharge is minor and will likely only contribute intermittently, and won t be considered as a dam recycled water source for this report s purposes. March 2008 Ref:

39 Local Government Area Wastewater Treatment Plant Proposed Discharge Strategy and Storage Logan Loganholme Loganholme s discharge to the Logan River is projected to increase to about 59 ML/d by Its closest PRW receiving dams would be either Wivenhoe/Somerset, or the proposed new Wyaralong Dam. Maroochydore Noosa Pine Rivers Maroochy Nambour Coolum Sunshine Coast Kenilworth Noosaville Cooroy Murrumba Downs Brendale Dayboro The Maroochy, Nambour, Coolum and Sunshine Coast WWTPs are projected to discharge over 66 ML/d to the Maroochy River by The receiving dam options would be Wappa, Ewen Maddock and Baroon Pocket Dams, or the proposed Traveston Crossing Dam. The Kenilworth WWTP is a minor facultative lagoon process. The net effects of evaporation and seepage are such that discharges are infrequent. Its discharge drains into the Mary River above the proposed Traveston Crossing Dam. The Noosaville WWTP currently discharges about 9.3 ML/d into Burgess Creek, and the Pacific Ocean. The receiving dam options would be Lake MacDonald or the proposed Traveston Crossing Dam. The Cooroy WWTP currently discharges about 1.0 ML/d into the Cooroy wetlands and Cooroy Creek. The receiving dam options would be Lake MacDonald or the proposed Traveston Crossing Dam. The Murrumba Downs and Brendale WWTPs are projected to discharge about 53 ML/d into the North Pine and South Pine River by Their closest PRW receiving dam would be North Pine Dam and Lake Kurwongbah. Alternatively, discharge would be to Wivenhoe Dam. The total discharge is currently 0.2 ML/d of which the majority is directed to irrigation. Excess discharge is to the North Pine River approximately 5 km upstream of the proposed North Pine Dam impoundment area. Redcliffe Redcliffe Redcliffe WWTP is projected to discharge about 17 ML/d into Moreton Bay by Its closest PRW receiving dam would be North Pine Dam. Alternatively, discharge would be to Wivenhoe Dam. Redlands Capalaba Thorneside Cleveland Victoria Point Mt Cotton Point Lookout The Capalaba, Thorneside, Cleveland, Victoria Point and Mt Cotton WWTPs all discharge into the ocean via local creeks. Their combined projected 2051 discharge is near 40 ML/d. Options for recycled water storage are Leslie Harrison Dam, Wivenhoe Dam via the Western Corridor pipeline, and the Stradbroke Island aquifer. Discharge from the Mt Cotton plant is unlikely to be used because of its small volume. The current Point Lookout WWTP discharge is minor. Discharge is currently to groundwater on Stradbroke Island. Toowoomba Wetalla The Wetalla WWTP is projected in 2051 to discharge 36 ML/d. Its closest PRW receiving dam would be Cooby Dam. A recycling scheme at Toowoomba is constrained by the cost of disposal of brine waste. Studies undertaken in 2005 identified that the Acland Mine would take approximately 6 ML/d of Grade recycled water with up to 3,000 mg/l of dissolved salts. An AWTP treating 23 ML/d of secondary effluent from the Wetalla WWTP, and producing 17 ML/d of PRW and 6 ML/d of Grade A water with its brine combined with the Grade A flow could therefore be achieved. Additional output from the Wetalla WWTP, after providing for the Millmerran power station would be surplus. March 2008 Ref:

40 4 Use of PRW to Supplement Water Supplies in South East Queensland 4.1 Recycled Water availability Principal Adopted for the Use of Recycled Water It is noted that in the past, a major driver for the use of recycled water for irrigation has been the maximization of the use of recycled water. Such use has been at a premium cost, however, when compared to traditional sources of irrigation water. The establishment of the recycled water pipe networks feeding PRW to the dams might open up opportunities to irrigate new areas because of the pipelines proximity to those areas, but the water will be expensive and treated to a level which would exceed most irrigation requirements. For this study the focus has been on the maximization of the use of PRW for supplementing municipal water supply. There may be opportunities for irrigation water use which emerge through optimization of the operating rules for the PRW system, but these opportunities have not been considered in this report Estimates of Recycled Water Use It is noted that this report s purpose is to estimate the full potential of recycled water as a supplement to natural sources such as dams or aquifers. In assessing such opportunities it has been necessary to consider what is already committed and to consider what portion of the committed use could be considered as essential use. Essential use is defined as that portion of the recycled water use for which maintenance of supply is important for the well being of the community. Such recycled water supplies would include recycled water used for commercial, industrial or essential environmental purposes. Commercial and industrial purposes have been assumed to include power station cooling, some agricultural and horticultural irrigation uses, and stand pipe tanker draw-offs. Recycled water that is not considered as essential would be recycled water that is used for the irrigation of parks, playing fields and golf courses (which is the great part of current recycled water use). This water has been assumed to be fully available for transferring to dams for inclusion in the raw water supply as supply becomes scarce. As previously noted, a number of the Brisbane Valley WWTPs purposely utilize effluent irrigation to minimize nutrient discharges into their receiving waterways. For this report s purposes, it is therefore not proposed that irrigation disposal restrictions would apply to these WWTPs. The WWTPs in the Brisbane Valley which would fall into this category include Toogoolwah, Lowood, Somerset Dam, Gatton, Helidon, Kilcoy, Laidley and Forest Hill. Also included would be other small WWTPs in the Logan, Albert and Bremer River valleys (i.e. Beaudesert, Kooralbyn, Jimboomba, Canungra, Logan Village, Boonah, Kalbar and Aratula). Table 4-1 sets out details of the current annual estimates of recycled water use. This information has been sourced from the report, Review of Use of Stormwater and Recycled Water as Alternative Water Resource. An assessment of that portion of the use considered to be essential has also been included. The minor Brisbane, Bremer, Logan and Albert valley LGAs have been marked Not applicable in that respect. March 2008 Ref:

41 Table 4-1 Year 2006 Recycled Water Use Local Government Area Indust l (%) Rural (%) Type of Recycled Use Park & Garden (%) Environ Flow (%) Golf / Sports Ground (%) Tanker Stand Pipe (%) Current Total Recycled Water Use (ML/a) Total Essential Recycled Water Use (ML/a) Beaudesert NA Boonah NA Brisbane ,457 1,957 Caboolture Caloundra Esk Gatton NA Gold Coast , Ipswich Kilcoy NA Laidley NA Logan Maroochy Noosa Pine Rivers Redcliffe Redlands 100 2,749 0 Toowoomba ,000 Totals: 17,204 3, Excludes 14 ML/d demineralised water transferred to BP refinery. 2. NA = Not applicable ML/a is currently supplied to Millmerran power station. The supply agreement allows for this value to be increased to 1,000 ML/a. The net difference between the annual totals of the current recycled water use ( committed ) and the essential recycled water use, i.e. the volume of recycled water used for park and golf course irrigation (for other than the minor Brisbane, Bremer, Logan and Albert River valley LGAs), is 12,999 ML/a Future Recycled Water Commitments Western Corridor Recycled Water Project The WCRWP will supply water to the Swanbank and Tarong power stations as well as potential indirect potable use supply to Wivenhoe Dam. The Swanbank power stations have demand for about 7,600 ML/a of cooling water. This will reduce to about 3,100 ML/a by 2026 when the more water efficient Swanbank F power station comes on line replacing Swanbank B. These power stations are currently supplied from the Wivenhoe and Moogerah Dams. The Tarong power stations have a water demand of about 33,200 March 2008 Ref:

42 ML/a (water efficiencies are currently being implemented to reduce that amount). Water for these power stations is currently supplied from the Wivenhoe and Boondooma Dams. The WCRWP is being designed to supply up to 110 ML/d (40,150 ML/a) of demineralised water to the power stations. This will replace the Wivenhoe and Moogerah Dam supplies allowing that water to be directed to potable use. Boondooma Dam is normally expected to supply 19,500 ML/a (53.4 ML/d) to the Tarong power stations but because of its unreliability Wivenhoe must allow for matching reserves at Wivenhoe. The net requirements for power station cooling water are therefore: ML/d ML/d There are three AWTPs providing recycled water for the WCRWP. Their respective capacities are: Luggage Point 66 ML/d Gibson Island 50 ML/d (The Gibson Island AWTP is likely to increase its PRW production rate to 100 ML/d). Bundamba 66 ML/d Up to 25,000 ML/a of Grade A+ water has been made available for irrigators in the Lockyer Valley, subject to conditions. SEQ Local Government Commitments The four major LGA s (which account for about 70% of the current SEQ water consumption) have provided the following advice with respect to future commitments for recycled water use. Such use is additional to that in Table 4-1. There may be other future recycled water use commitments with the other LGA s but they would be expected to be relatively small excluding the WCRWP. Brisbane City: Table 4-2 WWTP Brisbane City Future Additional Reuse Projections Additional Recycled Water Reuse Flow (ML/d) in Year Recycled Water Application Ultimate Gibson Island Demineralised water Luggage Point Demineralised water The ultimate values in Table 4-2 were assumed to be equivalent to a 2051 projection, and values for the years between 2031 and 2051 have been determined by linear interpolation. March 2008 Ref:

43 Gold Coast City: The Gold Coast Water document, Recycled Water Strategy FactsheetTwo lists a number of future recycled water opportunities which could be considered as commercial or environmental. These are summarized as follows: Environmental river flow replacement 7 14 ML/d Large scale Greenfield dual reticulation ML/d Opportunistic dual reticulation 0 20 ML/d Industrial recycling 0 7 ML/d Horticultural recycling 0 1 ML/d Additional on-site treatment < 1 ML/d Wetland regeneration < 1 ML/d The total of these uses ranges from about 24 to 114 ML/d. It is noted that the major difference between the upper and lower values is associated with the implementation of dual reticulation schemes. The lower end of the range has therefore been adopted for this report because it is expected that the main advantage of dual reticulation schemes, the reuse of reclaimed effluent, will be lost when PRW is returned to the storage dams. That range allows for continuation of the Pimpama-Coomera dual reticulation scheme. The Pimpama STP is a new waste water treatment plant currently being constructed. Its proposed Stage 1 development will have capacity to treat up to 17 ML/d to a Class A+ standard. There is capacity to transfer up to 12 ML/d to the Coombabah STP for discharge to the Seaway. The remaining 5 ML/d will be used for dual reticulation to replace existing residential potable demand for toilet flushing, irrigation and other external uses. Stage 2, which is proposed to be developed by 2012, will provide for upgrading the new plant to a 34 ML/d capacity. It has been assumed that the growth in reuse of recycled water for these uses would occur linearly from the current value in 2006 through to the long term total occurring in Ipswich City: Table 4-3 Ipswich City Future Additional Reuse Projections Additional Recycled Water Reuse Flow (ML/d) in Year Recycled Water Application Commercial/industrial Tanker filling for development It has been assumed that the growth in reuse of recycled water for these uses at Ipswich City would occur linearly from the current value in 2006 through to 2009, and subsequently March 2008 Ref:

44 Pine Rivers Shire: The Pine Shire is proposing to supply 4 ML/d of demineralised water to the Amcor paper mill. It is expected that the Amcor supply will commence during Toowoomba City: The Toowoomba City Council has a contract with the Acland Mine to take 3,000 ML/a of recycled water commencing in March, The mine has the option of increasing this to 5,500 ML/a if required. 4.2 Total water available for PRW use Error! Reference source not found. is based on the data provided in the preceding sections and summarises the net water available for PRW taking account of: The existing and future recycled water reuse commitments set out in Table 4-1 and Section 4.1.3; WWTP discharges which cannot be utilized because of their location or rate of discharge ; and The net recovery rate after advanced water treatment. Table 4-4 Projected Estimates of Possible Quantities of AWTP Discharge Year (ML/a) LGA Beaudesert 562 1,267 1,972 3,586 5,199 7,182 11,147 15,112 Boonah Brisbane 99,681 79,660 79,116 77,887 76,385 78,660 83,001 87,342 Caboolture 5,756 6,852 7,948 8,922 9,896 10,281 11,052 11,822 Caloundra 6,824 8,286 9,549 10,710 11,871 13,572 16,973 20,374 Esk Gatton Gold Coast 41,573 45,366 49,159 52,608 56,057 57,161 59,369 61,577 Ipswich 9,192 11,212 11,995 14,005 13,278 16,289 22,312 28,335 Kilcoy Laidley Logan 12,821 13,361 13,902 14,558 15,214 15,699 16,667 17,636 Maroochy 11,035 12,681 14,237 16,066 17,805 18,119 18,745 19,372 Noosa 3,089 3,300 3,510 3,633 3,756 3,762 3,774 3,787 Pine Rivers 7,222 7,261 8,650 9,502 10,354 11,158 12,766 14,374 Redcliffe 3,891 4,071 4,250 4,386 4,521 4,604 4,771 4,938 Redlands 8,141 9,002 9,864 10,679 11,494 11,525 11,589 11,652 Toowoomba 7,411 5,284 5,617 5,906 6,194 6,205 6,205 6,205 Less power station cooling water 40,150 40,150 40,150 40,150 36,280 36,280 36,280 36,280 Totals: 175, , , , , , , ,622 March 2008 Ref:

45 5 Potential PRW Schemes 5.1 Mixing Limits for Recycled Water Placement in Storages Dilution Modelling A dilution model was developed to determine recycled water ratios and detention times achievable from the existing and future SEQ storage volumes. The model was set up as an Excel spreadsheet to keep a daily record of the stored volume and the percentage recycled water in storage while recycled water was input and water was drawn off for water treatment. The model determines the worst case mixing ratios on the assumption that there is no rainfall/runoff inflow to the storage. Evaporation and seepage losses were allowed for using combined values provided by the Department of Natural Resources (DNR). A 0.8 pan evaporation factor was adopted. Dam storage and surface area values provided by DNR, as listed in Table 3-3, were used for the modelling. Several of the storages are a combination of multiple dams, e.g. Wivenhoe and Somerset Dams, Baroon Pocket and Ewen Maddock, and Wappa, Cooloolabin and Poona Dams. Provision was made in the model to assess the mixing ratios achieved in such multiple storages with the option of discharging the recycled water into only one of the storages, or equally into all. The Excel model used for the analysis makes no allowance for the dynamics of the water in the storage as it assumes that uniform mixing occurs. The model, however, is useful for screening of options in the first instance, but should investigations proceed detailed hydrodynamic modelling should be undertaken such as is currently being undertaken for the Wivenhoe dam Treated Water Draw-off Rates The dilution model is sensitive to the draw-off rate from the storage. In general, the higher the draw off rate, the quicker the recycled water fraction increases. The report, Regional Water Needs and Integrated Urban Water Management Opportunities Report, provided water demands for the SEQ LGAs from 2006 through to Table 5-1 is reproduced from that report and shows the basis of three water demand scenarios in the report which are associated with low, medium and high water savings scenarios. The dilution modelling was undertaken using the high water savings scenario and its demand predictions. This scenario was selected because it predicts a post-drought residential per capita water consumption closely aligned to the QWC s projected value of 230 L/c/d. March 2008 Ref:

46 Table 5-1 Low, Medium and High Water Savings Scenarios Table 5-2 provides a tabulation of the low water savings predicted demands (taken from Regional Water Needs and Integrated Urban Water Management Opportunities Report). It is supplemented with the following water substitution values to provide an estimate of the net water demands at the storage dam draw-offs: Existing and future residential and industrial users of PRW in Brisbane, Ipswich, the Gold Coast and Pine Rivers as outlined in Sections and It is noted that the Regional Water Needs and Integrated Urban Water Management Opportunities Report assumes that all power station cooling water demand would be met from PRW for each of the three considered water savings scenarios. Existing non-recycled water sources: Stradbroke Island Herring Lagoon, Stradbroke Island groundwater, Bribie Island aquifer and Toowoomba bores (28,000 ML/a); and Caboolture weir (5,475 ML/a). New non-recycled water sources: Gold Coast desalinisation (45,600 ML/a); March 2008 Ref:

47 Minor Brisbane aquifers (20 ML/d); and Recommissioned Manchester and Enoggera Dams (30 ML/d). Table 5-2 Projected Storage Draw-off Demands Year (ML/annum) LGA All of SEQ region 398, , , , , , , ,299 Less water replaced by PRW Less water from nonrecycled sources 1 9,490 16,106 23,216 30,326 40,174 41,148 43,094 45,041 33,475 97,325 97,325 97,325 97,325 97,325 97,325 97,325 Net SEQ region demands 355, , , , , , , , Table 5-2 assumes that the Gold Coast desalinization plant will be operated continuously at its full capacity. In practice, the supply from desalination may be reduced rather than the supply from dams and weirs. The water supply sources and storages will operate in the future as an interconnected water grid. For the purposes of this report, it has been assumed that the draw off, i.e. water supply demand, from each dam storage to meet the net SEQ region demands in Table 5-2 will be in proportion to the indicative Level of Service yields listed in Table 5-3. Table 5-3 Dam SEQ Water Supply Dams Draw-off Demands Draw-Off Demand LOS Yield (ML/annum) North Pine Dam and Lake Kurwongbah 39,900 24,997 33,056 Wivenhoe and Somerset 263, , ,134 Baroon Pocket and Ewen Maddock 35,500 22,240 29,410 Hinze (Stage 3) 58,200 36,461 48,217 Wappa, Cooloolabin and Poona 7,000 4,385 5,799 Cooby, Cressbrook and Perseverance 9,000 5,638 7,456 Lake MacDonald 3,500 2,193 2,900 Leslie Harrison 5, ,391 Wyaralong 29,500 18,481 24,440 Traveston Crossing (Stage 1) 70,000 43,854 57,992 Traveston Crossing (Stage 2) 110,000 68,913 91,131 Total 2026 (including Traveston Crossing Stage 1): 521, ,524 Total 2051 (including Traveston Crossing Stage 2) 1 : 561, , Assumes that Traveston Crossing Dam Stage 2 is developed after Excludes Borumba Dam Stage 3. It is noted that the draw-off demands in Table 5-3 are approximations made for the purposes of this report only. Specifically, the draw-off demands are based on: medium series population growth; March 2008 Ref:

48 LOS yields without an allowance for the potential impact of climate change of the yield of dams and weirs; and full utilisation of desalination and other sources of supply. Additional sources of supply are forecast to be required by 2028 in the event of the high series population forecasts being realized while including an allowance for the impacts of climate change. In that event, the LOS Yields in Table 5-3 would be fully utilised at Indeed, those LOS Yields may be fully utilised earlier depending on a range of factors including whether water is made available for rural production on a temporary basis. 5.2 Modeling Options The options modelled for matching recycled water and receival storages using the information outlined above are summarized below. The number of options investigated varied between the storage dams depending on the likely possibilities: Wivenhoe and Somerset Dams All Brisbane (excluding Sandgate), Esk, Fernvale and Ipswich WWTPs All Brisbane (excluding Sandgate), Esk, Fernvale, Ipswich and Loganholme WWTPs All Brisbane, Esk, Fernvale, Ipswich, Loganholme, Beenleigh and Redlands WWTPs North Pine and Kurwongbah Dams All Pine Rivers, Redcliffe, South Caboolture and East Burpengary WWTPs All Pine Rivers, Redcliffe, Sandgate, East Burpengary and South Caboolture WWTPs Hinze Dam All Gold Coast WWTPs All Gold Coast WWTPs excluding Beenleigh Baroon Pocket & Ewen Maddock Dams Kawana, Caloundra and Landsborough WWTPs All Maroochydore WWTPs (excluding Kenilworth), and Kawana, Caloundra and Landsborough WWTPs Cooby, Cressbrook and Perseverance Dams Wetalla WWTP March 2008 Ref:

49 Wappa, Cooloolabin and Poona Dams Nambour WWTP Leslie Harrison Dam and Stradbroke Island aquifers Capalaba WWTP Bribie Island Aquifer Bribie Island WWTP Lake MacDonald Noosaville WWTP Wyaralong Dam Beaudesert North WWTPs Beaudesert North and Loganholme WWTPs Beaudesert North, Loganholme and Beenleigh WWTPs Traveston Crossing Dam Stage 1 Maroochydore WWTP Traveston Crossing Dam Stage 2 All Maroochydore WWTPs (excluding Kenilworth), all Caloundra WWTPs (excluding Maleny) and Noosaville WWTP Each option was modelled for both the 2026 and 2051 PRW inflows and water supply draw-offs. 5.3 Modelling Results Interpretation of Results Table 5-4 summarises the modeling results. The numbers highlighted with shading are the PRW percentages where either the detention time was less than 12 months or the PRW percentage exceeded 40%. Mostly, the determining criterion was the PRW percentage. Detention times for the majority of the options were three to four years (assuming full mixing). The column marked Percentage Recycled Water in Storage After (Years) shows the PRW percentages in increments of 0.5 years up to 3.0 years assuming the storage is full at the commencement of the discharge of PRW to the storage and for no inflow to the storage. This is a worst case scenario as any rainfall/runoff which might occur would dilute the recycled water component in the storage, extend the detention time and reduce the recycled water percentage. March 2008 Ref:

50 As stated previously a PRW scheme has been considered to be acceptable if the storage could accept recycled water for two or more years whilst ensuring that the proposed detention period and recycled water percentages are achieved. Discussion on the results for each storage follows. March 2008 Ref:

51 Table 5-4 Results of Storage/Recycled Water Receival Options Modeling Dam Storage Description Year Option Percentage Recycled Water in Storage After (Years) Recycled Water Inflow (ML/d) Water Demand (ML/d) Detention While < 40% Recycled Fraction (Years) Wivenhoe Dam All Brisbane (excluding Sandgate), Esk, Fernvale, and Ipswich WWTPs All Brisbane, Esk, Fernvale, Ipswich, and Loganholme WWTPs All Brisbane, Esk, Fernvale, Ipswich, Loganholme, Beenleigh and mainland Redlands WWTPs North Pine Dam and Lake Kurwongbah All Pine Rivers, Redcliffe, South Caboolture and East Burpengary WWTPs All Pine Rivers, Redcliffe, Sandgate, East Burpengary and South Caboolture WWTPs Hinze (raised) Dam All Gold Coast WWTPs All Gold Coast WWTPs excluding Beenleigh Baroon Pocket & Ewen Maddock Dams Kawana, Caloundra and Landsborough WWTPs All Maroochydore and Caloundra excluding Kenilworth and Maleny WWTPs Cooby, Cressbrook and Perseverance Wetalla WWTP March 2008 Ref:

52 Dam Storage Description Year Option Percentage Recycled Water in Storage After (Years) Recycled Water Inflow (ML/d) Water Demand (ML/d) Detention While < 40% Recycled Fraction (Years) Wappa, Cooloolabin and Poona Dams Nambour WWTP Leslie Harrison Dam Capalaba WWTP Lake MacDonald Noosaville WWTP Wyaralong Dam Beaudesert North WWTPs Beaudesert North and Loganholme WWTPs Beaudesert North, Loganholme and Beenleigh WWTPs Traveston Crossing Dam (Stage 1) Maroochydore WWTP Traveston Crossing Dam (Stage 2) All Maroochydore WWTPs (excluding Kenilworth), all Caloundra WWTPs (excluding Maleny) and Noosaville WWTP Notes: 1. Allows for 7,600 ML/a of PRW being supplied from WCRWP to Swanbank power stations. 2. Allows for 3,100 ML/a of PRW being supplied from WCRWP to Swanbank power stations. March 2008 Ref:

53 5.3.2 Wivenhoe Dam Three recycled options have been considered. All options show that the 40% mixing criteria is not exceeded for in excess of 2.5 years of recycled water inflow. Recycled water percentages did not exceed 25% for nearly two years. The detention times were in excess of four years in all cases. The model assumes that the physical infrastructure is in place to allow the available PRW to be delivered to the dams. The Western Corridor pipeline is currently being constructed to transfer PRW from the Ipswich and Brisbane plants, excluding Sandgate. The inclusion of the Loganholme WWTP effluent is also being considered. The inclusion of PRW from the Redlands and Beenleigh WWTPs would require future augmentations to the current pipeline works. It is noted that Somerset Dam has not been included as part of the Wivenhoe Dam as it is effectively isolated from the Wivenhoe Dam North Pine Dam and Lake Kurwongbah Two options were investigated. In both cases, all available PRW from the Pine Rivers and Redcliffe, Sandgate, East Burpengary and South Caboolture WWTPs has been directed to the North Pine and Kurwongbah Dams. In the second option, PRW from the Sandgate WWTP was also included. The suggested mixing criteria were not exceeded for up to about two and one half years. The detention times were over three years in all cases. The modelling assumed that both North Pine Dam and Lake Kurwongbah were the receiving storages. This will require a complicated flow splitting system. It is noted that modelling for North Pine Dam alone gave similar results to that of the two dams combined Hinze Dam Two recycled water inflow options have been considered. One option included the Beenleigh WWTP PRW and the other did not. Both options show that the 40% mixing criteria is not exceeded for well over two years of recycled water inflow for all cases. The detention times were for all cases in excess of four years Baroon Pocket & Ewen Maddock Dams Two options have been considered. For the first option, all available PRW from the Kawana and Landsborough WWTPs was directed to the Baroon Pocket and Ewen Maddock Dams. For the second option, all available PRW from the Maroochydore WWTPs (excluding Kenilworth) was added to that from the Kawana and Landsborough WWTPs. March 2008 Ref:

54 The results of the modelling showed that the mixing criteria were exceeded for both options in less than 1.5 years. These storages would only be useable, while adopting the suggested mixing limits, if the recycled water inflows were significantly reduced The detention times were equal to or over two years in all cases Cooby, Cressbrook and Perseverance Dams For this scheme all available PRW from the Wetalla WWTP was directed to the Cooby dam which is part of the Toowoomba Water Supply System. Water would be pumped from the Cooby Dam to the Mt Kynoch Water Treatment Plant. The modelling assumed that dilution inflows would be provided to Cooby Dam from Cressbrook and Perseverance Dams, i.e. the current pumped discharge from those two dams would be diverted to Cooby Dam. The detention time and mixing criteria were exceeded after two years for the year 2026 case. However, these storages were found to be sensitive to the rate of PRW inflow. When the 2051 rate was reduced from 17 to 14 ML/d, the mixing ratios were reduced to within the suggested guidelines. The detention times were over three years in both periods Wappa, Cooloolabin and Poona Dams The modelling has shown that the dam needed to have an inflow less than the Nambour WWTP discharge of about 6 ML/d if it was to meet the suggested mixing criteria Leslie Harrison Dam The estimated quantities of PRW available from the Redlands Shire mainland WWTPs were estimated to be about 32 ML/d in 2026 and Leslie Harrison Dam was not able to accept that order of recycled water inflow but modelling showed that inflows of about 6-7 ML/d would be acceptable. This was confirmed by the results of modelling for the Capalaba WWTP PRW inflow option, as set out in Table 5-4. It is shown above that Redlands WWTPs PRW could be discharged to the Wivenhoe Dam but there it could require augmentation of the Western Corridor pipeline. An alternative receival storage for the Redlands water could be the North Stradbroke Island aquifers. Introduction of PRW to the North Stradbroke Island aquifers would be sensitive and it is noted that proposals for doubling the current groundwater extraction from Stradbroke Island have recently been stopped because of environmental concerns. It might be feasible to overcome those concerns by showing, through extensive groundwater modelling, that the possible negative impacts of groundwater extraction could be countered by the prudent application of PRW to the aquifers. If that could be achieved, it might be possible to return half the future extraction rate, i.e. approximately 22 ML/d, to the island as PRW for aquifer recharge. March 2008 Ref:

55 5.3.9 Bribie Island Aquifer In Section it is advised that the Bribie Island aquifer project will provide a new borefield with a net yield of about 6-7 ML/d. The projected 2051 AWTP discharge from the Bribie Island WWTP is about 6.8 ML/d. It could be possible that about half that rate could be returned as PRW to the Bribie Island aquifer Lake MacDonald The projected 2051 AWTP discharge from the Noosaville WWTP is 9.5 ML/d. Modelling of that treatment plant s discharge to Lake MacDonald has shown that only about six months of discharge could be accommodated before the guideline limits are met. Further, the minimum twelve months detention period would not be achieved with these small inflows Wyaralong Dam Three options have been considered: PRW from the northern Beaudesert area WWTPs; PRW from the northern Beaudesert WWTPs plus Loganholme WWTP; and PRW from the northern Beaudesert WWTPs plus Loganholme and Beenleigh WWTPs. The first option (northern Beaudesert WWTPs only) met the suggested dilution criteria for both 2026 and The suggested mixing ratios were extended to approximately two and one half years for the 2051 inflows. The detention times for that option were in excess of four years. However, it is noted with this option that urban development growth within the northern areas of the Beaudesert Shire will be relatively slow until after Development of an AWTP for this option would best be deferred until that period Traveston Crossing Dam Stages 1 and 2 Modelling for this scheme for the two possible two stages of development was undertaken assuming that the dam would receive PRW from all the Sunshine Coast WWTPs. Traveston Crossing Stage 2 was found to be able to comfortably achieve the 40% mixing criteria after three years of inflow in 2051, whilst detention times were close to five years. Staging of PRW inflow would be necessary to match the Stage 1 development of the Traveston Crossing Dam which has a smaller storage than Stage 2. For the Stage 1 development of Traveston Crossing Dam only PRW from the Maroochy WWTP could be utilized if satisfactory mixing criteria and detention times were to be achieved. The mixing criteria were found to be satisfactory until 2026 but the inflow would need to be reduced by 2051 if Stage 2 of the Traveston Crossing Dam did not go ahead. March 2008 Ref:

56 5.4 Summary of Modelling Investigations Preferred PRW Options Table 5-4 summarises those WWTP/storage combinations which met the suggested mixing and detention criteria in the modelling investigations. These options are preferred for further investigation and have been ranked in that table in order of highest PRW reuse. The maximum dilution percentage of these schemes after two years of discharge was 35% and the minimum detention period was 3.9 years. Table 5-4 Preferred PRW Options Recycled Water Flow (ML/d) WWTP Storage All Brisbane (excluding Sandgate), Esk, Fernvale, Ipswich and Loganholme WWTPs Wivenhoe Dam All Gold Coast WWTPs Hinze Dam All Maroochydore (excluding Kenilworth), all Caloundra (excluding Maleny) and Noosaville WWTPs Traveston Crossing Dam Stage All Pine Rivers, Redcliffe, Sandgate, East Burpengary and South Caboolture WWTPs Capalaba, Thorneside, Cleveland and Victoria Pt WWTPs North Pine Dam and Lake Kurwongbah Leslie Harrison Dam and North Stradbroke Island aquifer Wetalla WWTP Cooby, Cressbrook and Perseverance Dams Beaudesert North WWTPs Wyaralong Dam Bribie Island WWTP Bribie Island aquifer 3 3 Totals: 596 (217,564 ML/a) 768 (280,320 ML/a) The WWTP/storage combinations which are not proposed to be further investigated are summarized as follows: Baroon Pocket & Ewen Maddock Dams The discharge of recycled water from the Caloundra and Maroochydore WWTPs to these dams is feasible, while meeting the suggested criteria, if the not all the treatment plant discharge was sent to the two dams. However, the option of discharging to the Traveston Crossing Dam (Stage 2) comfortably met the mixing and detention criteria without any discharge restrictions. Discharge to the Traveston Crossing Dam would only require one point of discharge whereas discharge to the Baroon Pocket and Ewen Maddock Dams would require some form of flow splitting to the two receiving storages. The Traveston Crossing Dam option is therefore preferred even though it likely cannot be fully affected until after March 2008 Ref:

57 Wappa, Cooloolabin and Poona Dams The discharge of recycled water from just the Nambour WWTP (6 ML/d) resulted in exceedance of the suggested mixing criteria. This option was therefore rejected because it was unlikely to be an economical proposal. As for the discharge to the Baroon Pocket and Ewen Maddock Dams, there would also have been operational problems of having to split recycled water discharges between at least the Wappa and Cooloolabin Dam storages. Lake MacDonald Dam The discharge of recycled water from the Noosaville WWTP (9 ML/d) resulted in exceedance of the suggested mixing criteria. This option was therefore rejected because it was unlikely to be an economical proposal. Wyaralong Dam The inclusion of discharges from the Loganholme and Beenleigh WWTPs with that from Beaudesert North resulted in acceptable mixing criteria up to However, the projected high rate of growth in North Beaudesert after 2020 resulted in exceedance of the criteria by 2051 when combined with inflow from the Loganholme and/or Beenleigh WWTPs Increases in Dam and Aquifer Yield Table 5-4 provides an estimate of the annual total use of PRW if all the schemes listed were implemented. Those values, 217,564 ML/a in 2026 and 280,320 ML/a in 2051, represent respectively a potential 34% and 44% increase in annual yield over SEQ s existing and planned supply resources (including Traveston Crossing Dam Stage 2). It is noted that these potential increases in yield could reduce in times of extended drought, i.e. droughts extending for more than two years, if the suggested dilution and detention criteria are exceeded. The true additional yield associated with each recycled water input can only be estimated by carrying out a historical daily rainfall model for each dam in conjunction with the recycled water flows set out in this report, and any adopted detention and recycled water percentage guidelines. March 2008 Ref:

58 6 Recycled Water Scheme Costs 6.1 Costing Basis Preliminary estimates have been prepared for the schemes listed in Table 5-4 to determine their overall first order costs, primarily to economically rank the effectiveness of each scheme AWTP Costs AWTP Capital Costs All the schemes listed in Table 5-4 require the recycled water to be treated to a PRW standard. Figure 6-1 is a curve showing preliminary estimates of the capital cost of adding an AWTP to an existing WWTP Cost ($M) Secondary Effluent Feed (ML/d) QWC AWTP cost data Poly. (QWC data less phosphorus precipitation and sludge dew atering) Figure 6-1 AWTP Capital Cost-Capacity Curve The curve has been prepared by placing a trend line through AWTP cost data provided by the QWC. That data represented estimates recently prepared for a number of AWTP options for the current WCWRP. A cost adjustment was subsequently made for alum dosing, phosphorus precipitation, sludge thickening and dewatering being undertaken within the existing sewage treatment plants - these processes are generally included within the AWTPs for the WCWRP. The estimates of cost include on-costs, contingencies and margins. Unless otherwise noted, it was assumed that the existing WWTPs would have adequate solids handling capacity to cater for the new AWTPs. March 2008 Ref:

59 Figure 6-1 shows that there is an economy of scale for the development of AWTPs. For example, the capital cost of PRW from a 100 ML/d inflow plant is about $2.90/ML/d as compared to $3.75/ML/d for a 20 ML/d inflow plant. It is noted that small schemes, such as the Noosa and Bribie schemes, which could have inflows of less than 5 ML/d, are estimated to incur AWTP capital costs of greater than $8 per ML/d of inflow. These small schemes are therefore not likely to be economical. AWTP Operating and Maintenance Costs Operating and maintenance costs have been prepared for a range of plant sizes using detailed estimates prepared in 2007 for the Luggage Point AWTP as a guide. The costs were broken down into labour, power, chemicals, sludge disposal, maintenance and repairs, administration, and outside services. The major components are electrical power and chemicals which account for between about a half and two-thirds of the overall operating and maintenance costs, depending on the size of the AWTP. An energy cost of 8.1 cents per kwh has been adopted. Figure 6-2 summarises the estimated AWTP operating and maintenance costs Operating and Maintenance Cost ($M/annum) Secondary Effluent Feed (ML/d) Figure 6-2 AWTP Operating and Maintenance Cost Curve Pipeline Costs Pipeline Capital Costs Figure 6-3 is a curve showing preliminary estimating rates for greenfield pipeline construction. March 2008 Ref:

60 6,000 5,000 4,000 Cost ($/m) 3,000 2,000 1, ,000 1,500 2,000 2,500 Nominal Diameter (mm) QWC Pipe Cost Data Poly. (Greenfield Pipe Costs) Figure 6-3 Pipeline Capital Cost-Nominal Diameter Curve Pipeline construction rates have been rising dramatically over the last two years. The preliminary estimate rates in Figure 6-3 were projected from documented year 2004 rates and calibrated against recent pipeline estimates prepared for the WCWRS. These estimates include pipe supply, trench excavation, and the pipeline bedding, laying, backfilling and reinstatement, on-costs, contingencies and contractor margins for greenfield construction sites. The curve in Figure 6-3 has been drawn through greenfield data points. Table 6-1 sets out the locality factors which have been applied to the rates in Figure 6-3 to cover construction in non-greenfield areas. These factors have been developed by identifying the type of area (i.e. greenfield, rural, low density urban, etc) that selected projects were constructed in, and than estimating a locality factor for those projects based on the actual cost of work as compared to cost of similar work in a greenfield area. Table 6-1 Pipeline Construction Locality Factors Area Locality Factor Greenfield 1.0 Rural 1.3 Low Density Urban 1.6 General Urban 1.9 Dense Urban 2.4 March 2008 Ref:

61 Pipeline diameters have been generally calculated using an assumed flow velocity of 1.4 to 1.6 m/sec. Transfer flows have been assumed to drawn from flow balance tanks allowing for an equal pumping rate over a 24 hour period. Pipeline Operation and Maintenance Costs The 1989 Queensland Water Resources Commission Guidelines for Planning and Design of Urban Water supply Schemes recommended a range of maintenance costs for ductile iron (0.2 to 0.7% per annum of the capital cost) and steel pipelines (0.7 to 1.0% per annum of the capital cost). All of the pipelines being considered in these evaluations would be carrying either low nutrient secondary treated effluent or purified recycled water requiring relatively infrequent scouring. The maintenance and operating costs would therefore be expected to be at the lower ends of the given ranges. As a general guideline, ductile iron pipes are more economical than steel for diameters of less than 600 mm. The following pipeline annual maintenance costs have therefore been adopted for this report s purposes: Diameters < 600 mm 0.2% of capital cost Diameters > 600 mm 0.7 % of capital cost Pumping Station Costs Pumping Station Capital Costs Preliminary estimates of cost for secondary effluent and PRW pump stations are shown on the curve on Figure Cost ($M) Pump Capacity (ML/d) Figure 6-4 Pump Station Capital Cost-Capacity Curve The curve has been prepared using a CH2M Hill estimating model for water and wastewater treatment processes. The estimates of cost include on-costs, contingencies March 2008 Ref:

62 and margins and assume that the pumps are dry-mounted in a containment building and draw from a storage balance tank. Pumping Station Maintenance and Energy Costs The 1989 Queensland Water Resources Commission guidelines recommended that a maintenance cost of 3% per annum of the capital cost be adopted for centrifugal pumping equipment. A pumping energy cost of 8.1 cents per kwh has been adopted for pumping costs (as for the AWTP operating cost estimates) All of Life Costs All of life costs have been estimated for the considered schemes using the Net Present Value (NPV) method. The scheme NPV s have been estimated using the following inputs: Capital costs being input in the first year of the scheme. The scheme being analysed for 25 years of operation from the completion of the capital works. Residual values being applied to the capital costs assuming a linear depreciation, and assuming the following economic lives: Pipelines 50 years Pump-sets 25 years AWTP civil/structural works 45 years AWTP mechanical/electrical works 25 years (The split in costs for civil/structural to mechanical/electrical works has been estimated for AWTP works to vary from 84/16 for a 5 ML/d plant to 72/28 for a 100 ML/d plant). A discount rate of 7.5% per annum. The comparison of schemes has been undertaken using levelised costs. These have been prepared by dividing each scheme s NPV by the equivalent NPV of the water produced as PRW, i.e. the annual PRW production discounted to a present value over 25 years at a 7.5% p.a. discount rate. 6.2 Scheme Costs Exceptions Preliminary cost estimates follow for each of the schemes listed in Table 5-4 with the following exceptions: March 2008 Ref:

63 WCRWP: The WCRWP is currently under construction. Detailed cost estimates have been prepared by the scheme manager, the Coordinator-General s Department. Noosaville and Bribie Island WWTPs: As discussed in Section 6.1.1, small schemes such as these are not likely to be economical and have not been further assessed Gold Coast Scheme Figure 6-5 shows a possible pipeline route layout for a Gold Coast scheme. This scheme would utilize one AWTP at the Merrimac WWTP. The other Gold Coast WWTPs would direct their treated effluent to the Merrimac plant. Brine from the Merrimac AWTP would be directed to the brine outfall tunnel which has been constructed for the Tugun desalinization project. It is noted that the spare capacity currently available in that pipeline would likely not be available if the Tugun desalinization plant were enlarged. Additional solids handling and dewatering provisions would need to be provided to cater for treatment of the additional flow directed to the Merrimac WWTP. The costs of building an AWTP at the Merrimac WWTP to suit the estimated 2026 inflows, and the inter-connecting pipelines, to suit 2051 flows, through to the Hinze Dam follow: Elanora transfer pump station to Merrimac AWTP $5.5 M Elanora transfer pipeline to Merrimac AWTP $20.2 M Coombabah transfer pump station to Merrimac AWTP $11.5 M Coombabah transfer pipeline to Merrimac AWTP $66.6 M Beenleigh transfer pump station to Merrimac AWTP $4.3 M Beenleigh transfer pipeline to Coombabah offtake $35.3 M Merrimac AWTP $312.6 M Additional sludge handling at Merrimac WWTP $8.0 M Merrimac transfer pump station to brine outfall $5.0 M Merrimac brine pipeline to Tugun outfall tunnel $37.7 M Merrimac transfer pump station to Hinze Dam $17.9 M Merrimac transfer pipeline to Hinze Dam $35.3 M Total: PRW delivered per day: $566.9 M M/d Capital cost per ML/d of PRW $3.69 March 2008 Ref:

64 Figure 6-5 Gold Coast PRW Scheme It is noted that the largest cost item is the Merrimac AWTP which accounts for about 70% of the scheme s capital cost. If smaller AWTPs were located at each of the WWTPs March 2008 Ref: