Life of asset planning for new mines faces increasing complexity, as locations become more space-constrained and BHP seeks to optimise environmental and social value outcomes for closure. Early planning at the design phase provides the best opportunity to integrate with mine plans and achieve this optimisation. To this end, BHP undertook an exercise in strategic thinking and collaborative cross-functional engagement with our teams across mine planning, closure planning, and engineering disciplines. In particular, we examined the concurrent optimisation of pushbacks (mine benches) and mined material management.  

As a result, the mine planning team at Western Australia Iron Ore (WAIO) developed the ‘Finish and Fill’ strategy: a strategy that looks to maximise opportunities to backfill open pits so that a pit is ‘finished’ and then ‘filled.’ Overall, it minimises the need for overburden storage areas for extracted materials, reducing the footprint of land disturbance and rehabilitation requirements and reducing the number for truck hours, man hours and diesel used. Other benefits for planned mining developments include: 

• Shorter haulage distances and fewer truck hours, which reduces operational greenhouse gas emissions (from diesel-based vehicles). 
• Fewer pit lakes are created, which may be a preferred outcome for local communities and Indigenous peoples.¹

The Finish and Fill strategy has been implemented as part of life of asset planning at WAIO for several planned mining locations.  Currently, we can only assess an estimated potential value of the strategy and as the projects are progressively mined, we will be able to understand the actual value using the results after mining.  

The cumulative financial, social and environmental value potential for WAIO from the different planned deposits and mines are estimates of the benefit from implementing the Finish and Fill strategy compared to a ‘business as usual’ plan for the same activity without this approach and includes: 

• Improved social value due to less land disturbance during operations and fewer pit lakes following closure (~1,800 ha less disturbance). 
• Optimised haul distance leading to potential reduction in CO2 emissions (~500 Kt GHG savings).
• Reduced closure cost due to less re-profiling, rock armouring, and revegetation, as well as fewer post-closure management requirements (~AUD 230M).
• Implementing safety by design through more efficient execution or works that reduces exposure of our people to safety hazards.

Integrating this practical thinking and problem-solving approach into strategic mine plans can be replicated across new developments at WAIO. The strategy could be applied more broadly for planned mining developments, especially for open pit mine sites, where the geology and operating conditions support this approach. 

¹ Closure planning considers alternative closure options and opportunities, and site-specific objectives are developed in consultation with local communities, Indigenous peoples, and other partners and stakeholders.