The quarry floor is the lowest level of working within a quarry.
The size of the quarry floor can vary depending on the surface
limits of the quarry (ie the surface area permitted within
the quarry boundary ), the
depth of working and overall slope angles of the quarry side
In many quarries the floor is used for placing quarry generated
waste, and it often contains silt lagoons or ponds. These lagoons
may contain water used in processing the minerals and frequently
are employed to settle fine suspended solids. Similarly, the
floor of the quarry is where most rainfall and surface water
collects. If pumping has been necessary during quarrying to
lower groundwater levels, the cessation of pumping after operations
finish may result in the groundwater returning to previous
levels (a process known as groundwater rebound).
Clearly the form, extent and content on materials placed upon
the quarry floor will greatly influence the after-use and restoration
arrangements within that quarry. Any buildings within a quarry
rely upon sound foundations and
it is necessary to undertake a number of investigations to
ensure this, including:
One of the most important factors is to establish the long
term drainage arrangements. Other issues include the safe access to
the floor of the quarry, whatever after use has been chosen
for the particular site, and the stability of
the slopes above. Any built development on the quarry floor
must not be too close to quarry faces so
that appropriate rockfall protection measures
can be put in place.
- Checking the level of solid bedrock across the quarry
- Checking the depths of weaker materials above the solid
- Establishing the groundwater levels
- Establishing the potential for flooding or groundwater
and shallows incorporated into quarry floor restoration.
When considering an appropriate after use, the effects of shadow
and shade in deeper workings should be taken into account.
Where restoration includes wet areas on the quarry floor consideration
must be given to the closeness of any civil or military airports.
Air strikes from birds are an increasing problem and steps
are required within 15 km of airports and air bases to remove
all potential nesting sites for birds such as geese and other
wildfowl and waders. Where water bodies cannot be avoided,
this involves ensuring there are no large beach-like areas
and the establishment of bush-type vegetation.
Undulating backfill to restore a quarry floor.