Quarrying or surface mineral extraction is an operation that involves the recovery of shallow mineral deposits from the ground through the removal of overlying rock by excavators and dump trucks.
- Typically quarries work to depths of 50 to 100m.
- Sites are carefully designed to ensure maximum mineral recovery with minimum disruption and where possible, our sites are worked in a phased way to minimise the site area being worked at any one time.
- Once the working area has been fenced, the first part of the process is to lift the soils. The top soil and sub soil is separately lifted and placed in mounds around the perimeter of the site. The mounds are then seeded to grass. These mounds, called baffle mounds, act as a visual screen and noise barrier to minimise the impact of the work to being undertaken.
- The next stage in the process is to excavate down to the minerals such as brick shales, clays, stone and aggregates. The material above the minerals is known as overburden and consists of rock which is predominantly shale, mudstone and sandstone.
- Material from the first area that is excavated is placed in to a mound, called the “overburden” mound.
- As an area is worked and the minerals are removed, it is subsequently refilled with the overburden from the next area. This process is repeated until all the minerals have been recovered, at which stage the final void (or hole) is “backfilled” using the material stored in the overburden mound.
- The soils are then replaced on to the site and restoration and landscaping is undertaken.