Colliery waste materials generated subsequent to the Mining Waste Directive (MWD) (2006) are outside the scope of the DoW CoP (see paragraph 1.11 of the DoW CoP). Historically generated materials are not covered by the MWD and may also fall outside use under the DoW CoP. It is generally the case that materials termed colliery spoil[1] can include overburden and mixed geology excavated as a part of the process of winning coal. Colliery spoil can also include coal processing wastes which may have been placed on the site of origin or on nearby sites as backfill after the mining process was completed.
Certain materials associated with collieries might be eligible for reuse under the DoW CoP:
- overlying soil materials;
- where the colliery spoil forms a minor component of the soil and stones materials that are to be reused, and the materials are otherwise within the scope of the DoW CoP;
- materials on the colliery site that are simply an overlying natural bedrock with no coal materials.
Agreement with the Environment Agency or Natural Resources Wales must be sought in a recognised customer engagement process and full requirements of the DoW CoP must be met. If formal responses are not received from engagement within 21 days, then under published customer engagement policies it can be assumed there is no objection to the specific materials reuse if the engineering works are also approved formally under the planning regime.
Where colliery spoil heaps pose a serious risk to the environment or human health due to instability, a reprofiling of materials may be required to reduce the stability risks. The mechanism to achieve reprofiling may include DoWCoP reuse of spoil materials on site of origin approach where this is agreed formally with the relevant regulator in writing.
[1] Colliery spoil is a colloquial term which refers to the materials in the sedimentary strata that are associated with the coal seam, but which are not the coal seams themselves, or are generated by processing the coal, i.e., burnt shale. Spoil on colliery sites (like many other naturally occurring geologic materials exposed to the environment) can include heavy metals and other contaminants that can be harmful to human health and the environment, including animals and flora making it unsuitable for certain uses. Combustible materials, which may be present, such as coal and other organic matter can, via a process of oxidation and heating, lead to spontaneous combustion and underground fires.
Colliery spoil materials can also be subject to erosion and instability, especially if it is not properly managed or stabilised.
