Ultimately Environment Minister Bill Marmion has the authority to scrap the project, but the Environmental Protection Authority’s recommended level of assessment effectively amounted to a “no to the proposal” in the words of its chairman Paul Vogel back in March.

Vasse coal project manager LD Operations is appealing against this decision and has also made several freedom of information applications to further support its case.

In the documentation received by ILN, LDO is basing key aspects of its appeal on the errors made by the EPA in its assessment process and on the principles of procedural fairness.

LDO is also arguing the information in its referral application was misrepresented by the EPA and the government agency undertook “selective” or incomplete consideration of advice from WA government departments.

Another concern was that the EPA’s judgement was made far too early, with more investigations required to properly understand the proposal area.

Frith and Ditton’s views

In a joint letter to LDO, Frith and Ditton outlined that the proposed underground coal mine could meet environmental objectives.

Their understanding was that the primary environmental concerns relating to Vasse mine design and associated subsidence were:

i) That the continuing functioning of the overlying Leederville Formation aquifer within the local hydrogeological system is not adversely affected by mining.

ii) That the impact of mining subsidence at surface is maintained at “imperceptible” levels and that any designed surface features of special significance are individually catered for in the mine design.

Their first view was that underground coal mining and preserving the integrity of surface and sub-surface features were not mutually exclusive.

“There are numerous case examples both in Australia and internationally whereby the design of underground coal mines has been specifically based upon the need to ensure that the utility of movement sensitive man-made structures and natural features is preserved,” they said.

Examples they referenced included the South Bulli and Dendrobium collieries, which worked either directly beneath or near large dams used in Sydney’s water supply.

They also cited the vast amounts of coal extracted beneath heavy population areas with very low subsidence by mines such as the Gretley Colliery.

Both consultants said the Tasman mine in New South Wales adopted a similar mining strategy to the Vasse project, due to the sensitive surface features which hosted TV and electricity transmission towers, plus the presence of natural cliff lines.

“Mining experience to date demonstrates that surface subsidence levels are low, controlled and within predicted and allowable levels,” they said of this mine’s performance.

Western Coalfield mines in the state, such as the Clarence Colliery, were also mentioned for the ability to safely work beneath sensitive hanging swamps, high cliff lines and state forest areas.

“The fact is that fit-for-purpose mine design can demonstrably be used to control mine subsidence according to many constraints, including surface and sub-surface hydrogeology,” the consultants said.

In terms of their plans for Vasse project, they noted the bord and pillar mining method would allow significant flexibility for controlling subsidence.

They also plan to design an extraction exclusion zone to protect areas where the Osmington Seam is uncomfortably close to the Leederville aquifer.

Coal pillars would also be designed with suitable geometries to make them “squat” or “indestructible” as part of a best practice planning approach.

“Whilst the Vasse coal project area contains both sub-surface hydrogeological and surface impact concerns, there are no obvious impediments as to why a workable mining strategy and associated mine layout design cannot be developed that fully caters for the defined environmental constraints,” the consultants said.

Frith founded Strata Engineering in 1996 and has worked with many longwall mines over the past three decades, including the re-design of panel layouts at Newstan and West Wallsend in the mid-90s to prevent potentially catastrophic overburden weighting.

Ditton was the principal geotechnical engineer of Strata Engineering before he operated under his namesake geotechnical services consultancy in 2007.

During a 20 year coal mining career he has spent 15 years purely in mine subsidence related work.

Recent work included providing subsidence predictions for Whitehaven’s Narrabri mine and he is performing a similar role for Vale’s Ellensfield longwall project in Queensland.

The Vasse project is about 15 kilometres from the town of Margaret River and is targeting 1-1.5 million tonnes per annum run of mine for a 15-20 year mine life.

The Vasse project was being advanced by LD Operations on behalf of its private owners, AMCI (70%) and Core Coal Holdings (30%).