Surface mining, including strip mining, openpit mining and mountaintop removal mining, is a broad egory of mining in which soil and rock overlying the mineral deposit (the overburden) are removed, in contrast to underground mining, in which the overlying rock is left in place, and the mineral is removed through shafts or tunnels.
Although an excavated site provides a nice flat surface to work on it exposes different types of foundation soil as the cut goes deeper. Typically, an excavation may have rock at the back or deepest part of the cut, then heavy clay changing to a loamy clay or topsoil at the front of the cut. Fig.(d).
Tight access excavation: In spaces where a bulldozer or other heavy equipment can't do the job, an excavation company has the tools and expertise to create space even in tight situations. Demolition: If an old shed or other structure is preventing you from adding on a garage or pool, an excavator can quickly demolish and remove it.
Though pile foundations transfer the load through friction and/or bearing, pier foundations transfer the load only through bearing. Generally, pier foundation is shallower in depth than the pile foundation. Pier foundation is preferred in a loion where the top strata consists of decomposed rock overlying a strata of sound rock.