1.Rock Drilling Eccentric Overburden Casing System is today's preferred method for drilling in difficult ground conditions, for example, where there are boulders or loose formations. Eccentric casing drilling system is the most economical solution because its ingenious reaming wing the bit is retrievable can be used at the next hole. This is particularly designed for shallow holes, as is often the case in water well drilling, geothermal wells, and shallow micro-piling work. EDS is ideal for short holes in consolidated overburden.