200(1)An employer shall ensure that there is no undercutting of the working face of a quarry except where a tunnelling method is used to remove rock.
200(2)Where a tunnelling method is used to remove rock in a quarry and the enclosing ground is not secure, an employer shall ensure that
(a)
every tunnel in which work is being carried on or through which persons pass is securely cased, lined, timbered, screened, rockbolted or otherwise made secure, and
(b)
no person is allowed to go beyond a cased, lined, timbered, screened, rockbolted or otherwise secured ground.