In a recent blog post Jeff Pope, manager of facility decommissioning and demolition services at infrastructure EPC company Burns & McDonnell, pointed out that there are multiple business cases for decommissioning and demolishing obsolete structures at inactive mines. With escalating prices for metals and minerals – including current highs for scrap metal values – clearing the way to return a mine to operational status, or exploring other beneficial uses, may be worth considering.
Though the market for scrap metal is notoriously volatile, today’s prices are at a peak and may warrant a renewed look at whether the economics have swung in favor of decommissioning a mining site that is no longer in active production, according to Pope. These values can be important factors that could make the project financially viable. Though carbon steel typically has the lowest scrap value due to the large amount on the market, it is often the case that other higher-value metal alloys have been used in equipment and structures.
Scrap values are at a 10-year peak, primarily because of restrictions on commodities coming from China. This is causing a domino effect within the steel industry, creating more demand for scrap metals and driving prices up. Owners and operators that may have been waiting to start decommissioning mine sites may not find a better time to begin. Scrap values have dropped by as much as 80% over a short period of time, even while a project is underway, so acting quickly to take advantage of today’s conditions may be advantageous in offsetting at least some costs, Pope stated. Much like a financial investment, timing the market to sell while prices are at their highest can be tricky, but waiting too long could mean a missed opportunity.
Decommissioning an inactive mine can position the site for a broad range of new uses. The process follows three essential phases:
• Planning development,
• Scope development, and
Planning may be the most essential to project success because it is where initial costs are estimated. This phase typically includes an investigation and assessment of any regulated materials that might be present on the site, either on the surface or below grade. Asbestos, polychlorinated biphenyls (PCBs), oil and chemicals, or other hazardous materials left on the property will require special handling and disposal.
It’s worth noting that a turnkey engineer-procure-construct (EPC) delivery model can yield many schedule efficiencies and cost savings, beginning at the planning phase. Establishing a contractual framework that brings together an integrated team of environmental specialists, engineers and construction professionals can yield many insights that enable cost savings and schedule efficiencies during the life of the project.
With a refined plan, scope development can begin. This process focuses on key objectives such as:
• Are all the structures being taken down to grade with foundations removed?
• Are there underground utilities that can be abandoned, or do they need to be removed?
• Are there key infrastructure elements, like substations, that could be moth-balled for potential future use?
With this basic understanding, a conceptual framework can be developed for what the site will look like afterward. With scope packages developed, requests for bid proposals can be submitted to subcontractors and vendors with specifications for what must be removed and what will need to remain in place. Drawings and specifications also will be developed at this stage.
Finally, in the implementation phase, the site prep and demolition work can begin. With geotechnical test results in hand, construction crews will have an accurate picture of both surface and subsurface conditions and a clear picture of the structures to be demolished and equipment that need to be removed and hauled away. The plan will direct construction crews on how to handle any impoundments for water or wastewater on-site and disposal areas for tailings and other mine waste, particularly if these materials are to be buried with surface revegetation.
Pope said decommissioning should be integrated as part of a long-term planning process that can help mine owners envision opportunities that may open up once a project is complete. An integrated EPC contractor can also help to explore options to reduce the carbon footprint and even reduce costs for future site uses, such as electrifying future operations with a grid connection instead of relying on on-site power facilities that often require natural gas or diesel fuel. With renewed attention to environmental, social and governance (ESG) considerations, renewable energy sources also may be considered for a repurposed mine site.