Santos Narrabri Gas Project Environemental Impact Statement, EIS, Chapters 11 - 20, in summary

And for all the information that it delivers about the project’s operations and impact, it’s not exactly an engrossing read. Gripping thriller or page-turning pot-boiler this isn’t.

Let’s put this in perspective. If you printed the report on single page A4 sheets, the entire document would stand just over 72cm high.

The good news is, we’ve done some reading and condensed the 7000-page epic into this three-part summary.

Part one of our reading list looks at chapters one through 10 of the report, with chapters 11 through 34 coming soon.

Each chapter links to the relevant section of the report and also to recent media coverage of the gas project.

Chapter 11 - Groundwater and geology

The project’s impact on groundwater is the most controversial issue, and hence this chapter is one of the most dense – so dense it gets its own breakdown.

In summary, Santos says the depressurisation of the aquifers won’t be an issue because of the thick rock layers between aquifers and the coal seams. Farmers and water users won’t notice the drop in the watertable, which is expected to be less than half a metre. The salty water from deeper within the ground won't contaminate the fresh water aquifers, because it will be sucked down and away from the fresh water through the process. The salty water extracted will be treated and reused (as mentioned in chapter 7).

Chapter 12 - Surface water quality

The risk of accidental spills of fuel, produced water and chemical into the surrounding waterways, namely the Bohena Creek and its tributaries, will be low risk if the standard procedures and mitigation controls are in place.

Those include: placing the Leewood water treatment plant outside the Pilliga forest, double-lining its storage ponds with seepage collection pumps installed between liners and beneath the secondary liner, monitoring water pipelines for pressure drops that indicate a leak and the option to shut a well off should an incident occur.

Dust from construction will be suppressed with produced water (salty water that has been extracted and treated), to stop it from drifting into waterways.

Chapter 13 - Hydrology and geomorphology

There is a low risk of increased localised flooding, changing the watercourse or destabilising its banks. Near the Leewood waste water treatment facility, increased flood depth and extend is expected, but it will be localised with a negligible impact.

A flood with up to 400 millimetres at Leewood would represent a low level hazard – a “probable maximum” flood at the facility would be a high-level hazard.

The managed release of treated water into Bohena Creek will only happen when it is flowing at least 100 mega litres a day and is likely to cause erosion or deposition, but mitigation measures make the impacts negligible. 

Chapter 14 - Soils and land contamination

The soil in the project area isn’t very fertile and has limited productivity capacity – only seven per cent of the area has been historically cropped.

The key potential impacts of construction will be loss of soil through water or wind erosion, but controls should prevent this.

The main potential impact during operation is the accumulation of salt in the soil at the treated water irrigation area. Areas with pre-existing land contamination were identified.

Chapter 15 - Terrestrial ecology

About 1.5 per cent of the native vegetation in the project area would be cleared – about 1169.9 hectares –  with about half to be rehabilitated following construction.

10 threatened plant species and 22 threatened  plant communities exist within the area. 32 threatened species of fauna were also found. 

Four threatened ecological communities were identified (a naturally occurring group of native plants and animals that interact in a unique habitat).

Project is “unlikely” to have a "significant impact" on the threatened flora, fauna or ecological communities.

Major facilities will be placed in previously cleared areas where practical 

Chapter 16 – Aquatic ecology

The region's aquatic ecological communities (animals and plants who live and revolve around the waterways) are already in a “reduced condition”, and the project will use mitigation strategies to prevent any further reductions.

There is a low risk to stygofauna (animals and plants that live in groundwater systems or aquifers), and none were found in the project area.

Santos will monitor waterways, to ensure  the treated water released into them isn’t having an bad impact

Chapter 17 – Property and land use

The project can co-exist with the other land uses, which include agriculture, forestry, bee-keeping and recreational activities.

Only 1.3 per cent of the agricultural land would be impacted.

Gas field development will only take place on private property where a land access agreement is in place, which includes compensation for landowners.

Chapter 18 – Air quality

Main risks to air quality in operation include nitrogen from the power generators at well pads and the flaring of gas. However all air emissions would meet air quality standards.

The emissions also have the potential the affect the clarity of the night sky, which could be a problem for the world-leading Siding Spring Observatory, which is about 80km south-west.

However, the report indicates it won’t be an issue because “air emissions would generally decrease with distance from the source and become indistinguishable from surrounding air quality”. 

Chapter 19 – Noise and vibration

Construction seven days a week in daytime hours, and will comply with noise management levels “with a small number of exceptions”. Construction because the localised and temporary nature of the construction, exceedances of the noise management levels are expected to be minor and temporary.

The project will operate continuously 24 hours a day. All gasfield infrastructure, including wells, will be located far enough from houses to comply the 35 decibel limit (unless there is a private agreement with the landholder). Mitigation measures will keep other infrastructure within the limit.

A 200m exclusion zone around Yarrie Lake will stop recreational users from being disturbed.

A noise management plan will be development, and individualised mitigation measures for any site that may need it.

Chapter 20 – Aboriginal heritage

There are 90 Aboriginal cultural heritage sites, but there are likely more that have not been identified yet. The project would “completely avoid” all 90 sites.

Scarred trees, stone artefacts, grinding grooves, historic shelters and burial places are all located within the project.

There are 550 registered aboriginal parties, which Santos has consulted with via community meetings, site visits and have allowed them to review draft cultural reports. Aboriginal communities would still have high levels of access to the Pilliga forest. 

If a new site is discovered during, nearby work will be stopped until management measures can be agreed and implemented.