Pipeline to the Sea
Feasibility Study — Phase 1
Prepared October 2008 by Tonkin Science Engineering
Published May 2011
Pipeline to the Sea: Feasibility Study - Phase 1
Prepared for the former Murray-Darling Basin Commission by Tonkin Science Engineering
Published by Murray-Darling Basin Authority
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This report may be cited as:Pipeline to the Sea: Feasibility Study – Phase 1
MDBA Publication No. 148/11
ISBN (on-line) 978-1-921914-11-9
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Cover image: “Salinity Interception infastructure at Bookpurnong SA. Main line for salinity water to evaporation ponds” Arthur Mostead
Preface
The Basin Salinity Management Strategy 2001–2015 is the Murray-Darling Basin Ministerial Council’s response to the threat of salinity to water quality, the riverine environment, regional infrastructure and productive agricultural land.
A key element of this Strategy was the implementation of a joint program to construct new salt interception schemes to offset a predicted 61EC future increase in average salinity at Morgan. With an increase in the number of operating salt interception schemes came the need to assess options for disposal of saline groundwater generated by these schemes.
Due to the controversial nature of disposal basins from a social and environmental perspective, more detailed assessments of a number of alternate disposal options have been carried out or are under way. One alternative for the Riverland is a pipeline to transfer saline water to the sea.
The Murray-Darling Basin Commission first assessed a pipeline to the sea to transfer saline water generated by salt interception schemes in the Murray-Darling Basin in 1990 (GHD et al, 1990). That assessment considered a combined pipeline to transfer water from the Sunraysia and Riverland areas (‘the Mallee Zone’) as well as a separate pipeline to transfer saline water east/upstream of Swan Hill (‘the Riverine Plains Zone’).
The objective of this latest feasibility report was to establish the feasibility of a pipeline/channel delivery system that would efficiently and effectively dispose of saline groundwater from the Stockyard Plain Disposal Basin in the Riverland Region of South Australia to the sea.
The key conclusion of this feasibility study is that a pipeline to the sea may have some promise in the longer term when or if the capacity of the existing basins is exceeded. This report has only been prepared to inform discussion around possible disposal alternatives. Any decision to build such a pipeline at some point in the future would require more detailed engineering and ecological assessments followed by an extensive consultation and approval process.
Table of Contents
Pipeline to the SeaFeasibility Study – Phase 1
Executive Summary
1.Introduction
1.1Project Objective
1.2Stockyard Plain Disposal Basin
2.Outline of Scheme
2.1Outline of Infrastructure
2.2Range of options considered
3.Other Options
3.1General
3.2Disposal to Existing Salt Fields
3.3Disposal of Salt
3.4Discharge to Morella Basin or Southern Lagoon of the Coorong
4.Pipeline Routes
4.1Alternative Routes
4.2Alternative Disposal Locations
4.3Options Assessed
5.Pipeline and Pumping Infrastructure
5.1System Description and Operating Philosophy
5.2Pipeline
5.2.1Pipe Size
5.2.2Pipe Material
5.2.3Pipeline Cost
5.3Pump Stations
5.3.1Number of Pump Stations
5.3.2Pump Station Cost
5.4Discussion
5.5Off Peak Pumping
5.6Energy Recovery
5.7Open Channels
5.8ETSA Upgrade
6.Marine Outfalls
6.1General
6.2Ecosystems at Outfall Locations
6.2.1Port Wakefield
6.2.2Port Gawler
6.2.3Middleton
6.2.4Murray Mouth
6.2.5Coorong Crossings (Hells Gate, Tea Tree Crossing, 42 Mile Crossing & South of Coorong)
6.3Impact of Discharge on Receiving Environments
6.3.1General
6.3.2Water Quality Policy
6.3.3Discharge Water Quality
6.3.4Required Dilution for Compliance
6.3.5Modelling of Discharge Mixing
6.3.6Risk Assessment
6.3.7Summary
7.Outfall Infrastructure
7.1Description of outfalls
7.2Outfall construction
7.3Pipeline to the Sea Outfalls
7.3.1Length of Outfalls
7.3.2Cost of Outfalls
8.Concentration Techniques
8.1Introduction
8.2Concentration via solar evaporation
8.3Climate Change
8.4Opportunistic production of other products
8.5Evaporation Basin Model
8.5.1General
8.5.2Model Methodology
8.5.3Model Inputs and Assumptions
8.6Area of Evaporation Basins Required
8.7Cost of Evaporation Basins
8.7.1Capital Cost
8.7.2Operation and Maintenance Cost
8.8Issues Associated with Evaporation Basins
8.9Concentration by Desalination
9.Ecological Issues
9.1Desktop Study
9.2Stockyard Plain Basin
9.3Pipeline Alignments
9.3.1Methodology
9.3.2Vegetation Types and Significance
9.3.3Summary of Vegetation Assessment
9.3.4Other Vegetation Issues
10.Aboriginal Heritage
10.1Desktop Study
10.2Aboriginal Heritage Sites
10.3Native Title
10.4Consultation with Aboriginal Groups
10.5Summary
11.Social Impacts
12.Comparison of Options
12.1General
12.2Total Cost
12.3Present Value Cost
12.4Cost per Tonne of Salt Removed
12.5Cost of Removing Salt by Truck
12.6Overall Comparison of Alternative Pipeline Alignments
12.7Comparison of Pipeline and Trucking
13.Technical Review Workshop
13.1Workshop Purpose, Attendees and Outcomes
13.2Phase 2
14.Conclusions
14.1Individual Conclusions
14.2Overall Conclusions
15.References
Tables
Table 4.1 – Alternative Pipeline Routes
Table 5.1 - Pipe Sizes Assessed for Different Velocities
Table 5.2 – Optimum Pipe Sizes
Table 5.3 – Pipe Details
Table 5.4 - Optimisation of Pipeline Size
Table 5.5 – Pipeline Capital Costs
Table 5.6 – Pipeline Friction (m/km) for Different Pipeline Capacities and Velocities
Table 5.7 – Number of Pump Stations for Each Pipeline Option (50 L/s)
Table 5.8 – Number of Pump Stations for Each Pipeline Option (100 L/s)
Table 5.9 – Number of Pump Stations for Each Pipeline Option (250 L/s)
Table 5.10 – Number of Pump Stations for Each Pipeline Option (375 L/s)
Table 5.11 – Number of Pump Stations for Each Pipeline Option (500 L/s)
Table 5.12 – Unit Cost for each Different Pump Station
Table 5.13 – Pump Station Capital Costs
Table 5.14 – Density of Pumped Water
Table 5.15 – Annual Pump Station Operational Cost ($ million)
Table 5.16 - Power Upgrade Costs
Table 5.17 - Costs to Upgrade Electricity Network
Table 6.1 – Water Quality Data for Stockyard Plain Basin
Table 6.2 – CORMIX Model Input Data for Receiving Waters
Table 6.3 – CORMIX Model Input Data for Outfall Discharge
Table 6.4 – Results of Initial CORMIX Model Runs
Table 6.5 – Results of CORMIX Model Runs for Different Outfall Pipe Sizes
Table 6.6 – Impact Assessment Matrix
Table 6.7 – Summary Risk Matrix
Table 6.8 – Summary Risk Assessment for Habitat and Species
Table 6.9 – Summary of Marine Outfalls
Table 7.1 – Outfall Lengths for Port Gawler Pipeline Options
Table 7.2 – Cost of Outfall Structures
Table 8.1 – Weather Data Used in Evaporation Basin Model
Table 8.2 – Area of Evaporation Basins for Salt Harvesting
Table 8.3 – Areas of Evaporation Basins for 300 L/s Inflow
Table 8.4 – Area (Ha) of Evaporation Basins Required to Concentrate Groundwater at Stockyard Plain
Table 8.5 - Estimated Cost of Reverse Osmosis Desalination Plants
Table 9.1 – Overall Significance Score
Table 9.2 – Roadside Vegetation Categories
Table 9.3 – Vegetation Scoring for Bow Hill to Tailem Bend
Table 9.4 – Roadside Vegetation Categories for Bow Hill to Tailem Bend
Table 9.5 – Summary of Roadside Vegetation Assessment
Table 10.1 – Consolidated List of Known Aboriginal Heritage Sites
Note:NNTT ID = National Native Title Tribunal Identification number
Table 10.2 – Native Title Claims
Table 10.3 – Aboriginal Stakeholder Groups
Table 12.2 – Overall Comparison of Pipeline Alignments
Figures
Figure 2.1 – Schematic Diagram of Project Infrastructure
Figure 4.1 – Alternative Pipeline Routes
Figure 4.2 – Longitudinal Sections of Pipeline Routes
Figure 5.1 – Pipeline Capital Costs
Figure 12.1 – Present Value Costs
Figure 12.2 – Cost per Tonne of Salt Removed
Appendices
Appendix A Fisheries Habitats
Appendix B Risk Assessment for Marine Habitats
Appendix C Risk Assessment for Marine Species
Appendix D Pipeline System Schematics
Pipeline to the Sea: Feasibility Study - Phase 1
Document History and Status
Rev / Description / Author / Rev’d / App’d / DateA / Draft for comment / RME / JPW / 7/11/07
B / Revised draft for workshop / RME / JPW / 21/4/08
C / Revised draft following workshop / RME / JPW / 30/6/08
D / Final / RME / PDC / PDC / 9/10/08
Pipeline to the Sea: Feasibility Study - Phase 1
Executive Summary
Key Conclusions
A pipeline to the sea is a promising option to remove salt from the Riverland region of South Australia some time in the future when additional volumes of saline groundwater are generated by new salt interception schemes and the capacity of existing disposal options is exceeded.
For the likely groundwater flows and salt loads to be disposed of in the short term, piping salt is not as cost effective as harvesting salt at Stockyard Plain Basin and removing by trucking. A drawback of this option however is that additional evaporation basins would have to be constructed to allow salt to be harvested
It is more cost effective to concentrate the groundwater at the StockyardPlainBasin before pumping to the sea. This indicates that the additional costs to concentrate the groundwater are more than offset by the reduction in pipeline cost by using a smaller pipe to transfer the same volume of salt.
The enhanced concentration of the groundwater generated by the salt interception schemes, possibly by desalination at the Stockyard Plain Basin, would reduce theinflow to the basin and extend its sustainable life beyond the currently estimated 100 years.
The most cost effective pipeline option is to concentrate brine at Stockyard Plain Basin and transport to Cheetham Salt at Dry Creek north of Adelaide. Although preliminary figures indicate that this option is not as cost effective as the trucking option it is considered that it warrants more detailed assessment as it re-uses a waste product and there is opportunity to offset costs against the reduced pumping which would be required by Cheetham Salt. If coupled with a desalination plant at Stockyard Plain Basin to concentrate the brine and produce fresh water as aby-product, the total project would be seen as turning a problem into a number of benefits.
If a pipeline to the sea was to be adopted in the future a detailed investigation would be required to more accurately determine costs for the preferred alignment and to determine the optimum time to cease disposal to Stockyard Plain Basin to ensure the long term ecological sustainability of salt interception schemes in the Riverland.
Objective
The objective of this study is to establish the feasibility of a pipeline/channel delivery system that will efficiently and effectively dispose of saline groundwater from the Stockyard Plain Disposal Basin in the Riverland Region of South Australia to the sea.
A pipeline to the sea would be expected to extend the sustainability of existing salt management basins in the region as well as delaying or negating the need for the development of additional salt management basins.
Methodology
The project was considered as consisting of three main components;
- Works required at Stockyard Plain to concentrate the salt load.
- Works required to transport the salt load from the Stockyard Plain Basin to the disposal site.
- Works required to dispose the salt load at the disposal site.
The efficiency of a salt disposal scheme can be measured by estimating the unit cost of salt removed from the Stockyard Plain Basin i.e. $/tonne. A number of alternative schemes were assessed by considering a range of pipeline capacities and salinities of pumped groundwater.
For this project a range of flows from 50L/s to 500L/s was considered for the disposal of groundwater from the Stockyard Plain Basin.
To cover the possible range of salinities to be pumped, the following salinities were considered when assessing the alternative schemes;
- 20000mg/L (lower limit).
- 60000mg/L (mid range).
- 100000mg/L (upper limit).
Alternative Options
Alternative pipeline routes were selected by consideration of potential disposal locations and proximity to the sea. The geography of the South Australian coastline highlights four principal disposal locations;
- Top of Gulf St Vincent.
- North of the city of Adelaide.
- The Coorong.
- Encounter Bay (Middleton).
The top of Gulf St Vincent is due west of the StockyardPlainBasin and a pipeline alignment would avoid any major townships. The nearest point on the coastline to the StockyardPlainBasin is north of the city of Adelaide. The Southern Ocean adjacent the Coorong is a logical destination because of its direct route and high energy coastline. The EncounterBay alternative was selected as it provides a shorter pipeline route than the Coorong option.
In addition to disposal of the saline water to the sea, disposal at the existing Cheetham saltfields at Dry Creek was considered.
For each of the locations a pipeline alignment was selected by following existing road reserves and existing or disused railway corridors. The alignments also cross the River Murray and other rivers and creeks at existing or disused bridges.
A total of four principal pipeline routes (A to D) and 11 alternative disposal locations were considered and are summarised in the following table.
Pipeline Route / Disposal Location / Length(km) / Maximum
Elevation
(m AHD) / Distance Pumped (km)
A1 / Port Wakefield / 210 / 460 / 120
A2 / Lochiel Salt Works / 220 / 460 / 120
A3 / Price Salt Works / 240 / 460 / 120
B1 / Dry Creek Salt Works / 160 / 380 / 85
B2 / Port Gawler / 155 / 380 / 85
C1 / Middleton / 255 / 150 / 150
C2 / Murray Mouth / 265 / 150 / 150
D1 / Hells Gate / 240 / 76 / 210
D2 / Tea Tree Crossing / 280 / 76 / 245
D3 / 42 Mile Crossing / 295 / 76 / 265
D4 / South of CoorongNational Park / 330 / 76 / 290
Pipeline Costs
For the range of options considered, capital and on-going costs were estimated for a pipeline and pumping system. Pipeline capital costs varied from $44million to $93million for the 50L/s capacity options and from $130million to $278million for the 500L/s capacity options.
For all pipeline options the capital cost of the pipeline is much greater than the capital cost of the pump stations. For the Port Gawler (B2) and Dry Creek(B1) options the cost of the pump stations is 10% to 25% of the pipeline cost, while for the options which discharge to the Southern Ocean the cost of the pump stations is 10% to 15% of the pipeline cost.
The capital cost of the pipeline for any particular option is much greater than the capital cost of the pump stations and the outfall structures. For the options which pump raw groundwater from the Stockyard Plain Basin the pipeline represents 65% to 75% of the capital cost for the Port Gawler options and 75% to 90% of the capital cost for the options discharging to the Southern Ocean.
It was also found that the pump station operating costs were small compared to the pipeline capital cost. Using a 30year period and 4% discount rate the present value of the operating cost for the Port Gawler options is 20% to 50% of the pipeline cost. For the pipeline options which outfall to the Southern Ocean the operating cost is between 10% and 15% of the pipeline cost, depending upon the pipeline capacity.
The existing ETSA Utilities electricity distribution network would require a significant upgrade south of Meningie and west of Blanchetown to cater for the proposed pump stations along the Coorong and Port Gawler pipeline options.
Concentration at Stockyard Plain
For the options pumping concentrated groundwater the area of evaporation basins required to achieve the desired concentration was estimated. To achieve the desired salinities it is necessary to line the basins to reduce the seepage rate. The cost of the basins was estimated using a rate of $35000 to $40000/ha. The capital cost of the basins becomes significant for these options and the pipeline cost becomes 40% to 50% of the total capital cost for Port Gawler options and 50% to 70% for other options.
Marine Outfalls
The composition of the groundwater being pumped into the StockyardPlainBasin is similar to that of seawater. The principal differences between the Stockyard Plain Basin water and seawater are elevated concentrations of oxidised nitrogen, ammonia, iron and manganese.
Based on the number of species and habitats the Southern Ocean marine outfall locations have a lower environmental risk than the Gulf St. Vincent marine outfall locations. However, results of the CORMIX modelling indicate that discharge from a single open pipe marine outfall without a diffuser structure should adequately mix to achieve acceptable concentrations of critical elements at the edge of the mixing zone as defined in the Environmental Protection (Water Quality) Policy, 2003.
Marine outfalls discharging to the Southern Ocean are likely to be shorter in length than those discharging to Gulf St Vincent because of higher energy waters and deeper water closer to shore.
The location of the outfall will be governed by specific site conditions and further detailed modelling using site specific data would be required before any definite decisions on outfall locations were made. In particular, site specific bathymetry and time series wind and current data to define the worst conditions scenario are required to allow more accurate modelling of the outfalls.
For each option discharging to the sea, capital and on-going costs were estimated for a marine outfall. The cost of all outfalls was much smaller than the pipeline cost.
Ecological Issues
To assess the nature and scale of matters of conservation significance likely to be encountered along the alternative pipeline routes the database of roadside vegetation mapping was used. From the database, the extent of high value vegetation was quantified as this was considered a good indicator of the potential for impacting on conservation values.
It was concluded that the risk of impacting on conservation values along the Port Gawler alignment is low while the risk of impacting on conservation values along the Coorong alignments is high.