Progress to date
The Gascoyne Food Bowl Initiative has achieved good results so far and is tracking on time and on budget.
Sourcing additional 4 gigalitres of water for horticulture completed
Sourcing water for an additional 400 hectares of land is a key objective of the Foodbowl project. Without supply of 4 GL/a at a peak demand of 400 L/sec, the goal of delivery of up to 10 ML/a to 400 ha would not be possible.
Exploration drilling focused on a 12km section (GFB Phase 2 area) north of the Gascoyne River upstream of Carnarvon.
These sites were selected using data collected from an airborne electromagnetic survey completed in 2013. The data was analysed with partners at CSIRO to identify the locations likely to contain the thickest sequence of permeable sands containing the lowest salinity groundwater.
Drilling and testing was completed in August 2015 – 12-months after starting. Exploration was undertaken at the 70 CSIRO ‘target’ sites and another 50 drilled to test alternatives for Production sites. Drilling was also undertaken to explore for addition opportunities for water in the first 11.5 km (Phase 1 Gascoyne Water Cooperative borefield; 12 sites) and out east between 24km to 35km section out to Rocky Pool (28 sites in the Phase 3 area). If found and proven sustainable, this water could be used to expand agriculture beyond the initial 400ha goal.
The final results show that 50% of the CSIRO selected AEM-target exploration wells and 30% of the alternative sites recorded the specified minimum requirement for conversion to Production Wells.
Thirty five (35) production bores were subsequently drilled in the Phase 2 area – at locations where aquifer yields were high, at a minimum distance from other production sites and at varying distances from the river – to account for collection of recharge and avoidance of brackish river flows. Other site factors included proximity to the proposed collector main and powerline.
Gamma logging to select the sand layers to screen and detailed water chemistry was completed at every production bore
Results from the drilling indicate that:
- Phase 1 Infill – 12 exploration sites identified five (5) potential locations for Production bores capable of a maximum instantaneous of 50 L/sec
- Phase 2 GFBI – 70 exploration sites from which 35 Production bores were installed capable of a maximum instantaneous yield of 550 L/sec.
- Phase 3 Exploration Phase – 28 exploration sites identified up to 19 potential Production bores that could deliver a maximum instantaneous over 160 L/sec.
Using the Results of the drilling and testing, DAFWA engaged CyMod systems to build a numerical model of the aquifer. We tested 5-scenarios across two differing climate (river flow) periods; 1990-2000 – regular river flows and recharge, and 2000-2015, irregular river flows and recharge for Basins B-L. The scenarios were; (1) GWC and Water Corporation using 3.6 and 6.1 GL/a without DAFWA at GFBI of 4 GL/a, (2) Scenario 1 plus GFB at 4 GL/a from 8 highest yielding bores, (3) Scenario 1 with GFBI at 8.5 GL/a from 8 bores, and Scenarios 4 & 5, using al the bores and extending the borefield another 5km upstream.
Results indicate that 4 GL/a is available from the GFBI area. Capability to install Production bores to access another 2 GL/a appears feasible from the Phase 3 area.
Results of the drilling (H3 Report – Global Groundwater) and CyMod modelling have been submitted to the Department of Water for decision on the requested GFB Water Allocation.
Switching on electricity in the existing Phase 1 GWC borefield on 17 December 2014 marked a significant achievement in the Gascoyne Food Bowl Initiative.
The replacement of costly diesel power generation with electric-powered water pumps is a major commitment of the $25 million program.
The Gascoyne supplies about 40 000 tonnes of horticultural produce to WA’s domestic market per annum, worth around $80 million (not including Wooramel).
Horizon Power was engaged by DAFWA in mid-October 2014 to build 12.5km of 22 000 volt line to power the existing northern borefield. Six local linesmen built the entire line, demonstrating the capability of Carnarvon locals to contribute to a project that will benefit the local community.
The new line travels to the 12km mark of the northern borefield, with several spur lines to production bores further from the main corridor.
It consists of 120 cyclone-rated poles, about 360 insulators, around 40km of cabling and 12 transformers.
This will significantly reduce pumping costs and create a more reliable power system for all growers and the community as a whole. This has been completed in the expected timeframe and on budget
Horizon Power have commenced installing the overhead 22 000 volt line in the GFB Phase 2 borefield (1.5 – 25km) and will be completed by June 30.
The final phase of the Infrastructure build includes the installation of 24km main collector main and connection of the Phase 1 GWC collector main to the distribution network. The Foodbowl collector main was designed by GHD in 2015 and all of the pipe purchased and delivered to site. The mainline includes 13km of 900 and 800mm pipe, and shorter lengths of 710, 650 and 560mm materials.
Contracts for installation have been awarded and construction will commence in April.
Technical studies including an airborne electromagnetic survey (AEM) analysis, soil surveys, revised floodway modelling, land use constraint mapping and flora and fauna surveys have been undertaken to identify suitable parcels of unconstrained land. As a result, about 600 hectares of high to moderate capability land has been identified for potential annual and perennial horticulture.
The GFB District Structure Plan and Scheme Amendments, which will incorporate the ‘new’ GFB land into the Shires town planning scheme, has been adoped by the Shire of Carnarvon and circulated for public consultation.
The town planning scheme is part of a parallel process to expand the land in Carnarvon. Department of Lands will continue to work on changing the title of the land from Unallocated or Vacant Crown Land and Pastoral lease tenure into a Section 79 lease (a General Lease granted for a purpose and subject to conditions), and then ultimately to freehold, which requires Native Title negotiations to occur first.
The Department of Lands is currently seeking approval from the Minister for Lands to proceed with tenure change and Native Title negotiations.
Once this occurs, information on the land release should be publicly available within a couple of months.
Announcement of contractors to undertake the Gascoyne Pipeline extension
Stage 2 Electrification commencing
Recommencement of drilling
Completion of pipe construction
The Gascoyne Food Bowl is a joint state agency project between:
- Department of Agriculture and Food, Western Australia
- Department of Lands
- Department of Regional Development
- Department of Water.
Other stakeholders include, but are not limited to:
- Shire of Carnarvon
- Carnarvon Growers Association
- Department of Main Roads
- Gascoyne Development Commission
- Gascoyne Water Cooperative and Gascoyne Water Asset Mutual Cooperative
- Horizon Power.
Newsletters are distributed every quarter to keep stakeholders informed of progress. If you want to subscribe contact Kirrily Palmer.