AGL has decided to cease a controversial irrigation program it has been running in the Gloucester valley for the past two years.
Subscribe now for unlimited access.
$0/
(min cost $0)
or signup to continue reading
The company says it will not extend the program blending fresh water from the Avon River and produced water from coal seam gas wells to irrigate fodder crops and pasture at its Tiedmans site west of Gloucester.
The program will end on April 30.
There has been conjecture over the future of the program in recent months, with members of the Gloucester Dialogue recently informed the program was unlikely to continue.
AGL has been omitted from the Dialogue at the request of Gloucester Shire Council.
Speaking at last Wednesday’s monthly meeting of council, Cr Frank Hooke said Dialogue members had been informed that the irrigation program had shown increased levels of soil salinity and the possible presence of heavy metals.
AGL has disputed this and says testing carried out at the site between July 31 and December 31 last year showed no impact to surface or underlying groundwater, while soils were also unaffected.
During the testing period, water balance calculations showed 27 per cent of the water applied to the Stage 1A area was blended water while 73 per cent was natural rainfall. No blended water was applied to the Stage 1B area.
AGL said the results indicated the following:
- Salinity (EC15) had decreased at depths greater than 20cm across all soil sampling sites, though salinity remains above the parent levels.
- Sodium (Na+) concentrations have increased at depths greater than 20cm across all soil sampling sites with no obvious adverse effect on soil structure.
- The net mass balance indicates salts are gradually accumulating in the soil profile. However, this is likely to reduce with the decrease in irrigation operations over the next 12 months.
- There is no evidence of adverse effects to soil structure caused by the irrigation with blended water.
AGL started the main Tiedmans program in April 2013.
“We’ve been really happy with the results from the Tiedmans irrigation program and as we only have a very small volume of produced water left, we made the decision not to apply for an extension of the program,” AGL’s hydrogeology manager John Ross said.
“As at the end of March we have blended 52 megalitres of produced water from our earlier exploration programs with freshwater and used 116 megalitres of water in total to irrigate crops including lucerne, triticale and forage sorghum and an area of improved pasture.
“More than 1000 bales of silage-fodder have been produced to support local agriculture production activities.
“Our monitoring reports have confirmed that there has been no impact to adjacent surface water resources and underlying groundwater. There have been no adverse impacts to soils and the fodder has been proven to be suitable as supplementary feed for cattle and sheep.”
The remainder of the produced water will stay in one of the holding ponds at the Tiedmans property and be treated by reverse osmosis when the water treatment plant is built as part of stage one of the Gloucester Gas Project, AGL said.
AGL said there were currently 15 reports online with information on the produced water, storage dams, blended water and irrigated crops (as well as local water receptors and soils).
The Tiedmans irrigation program was approved by the Office of Coal Seam Gas.
There is currently 15 megalitres of blended water still stored on the Tiedmans property and AGL expects to use most of the water for irrigation prior to the April 30 deadline.
An AGL spokesman said it was still exploring all options for disposal of flowback water from its coal seam gas project and negotiations with a third party contractor were continuing.
“When we have more details we will share them with regulators and the community,” the spokesman said.
Flowback water is the water pumped into the well during the fracking process while produced water is old water, usually high in salt content, from coal seams.
