In geothermal drilling bore wells are drilled to extract heat stored in earth. In shallow geothermal drilling, typically two geothermal wells with diameter 4.5 or 5 inch are drilled to a depth of 180-300 meter. Water contained in water table is used to transfer the energy from the Earth to the ground. This energy is used to heat homes and it can safe up to 30 % of the energy cost. Geothermal heating of houses are increasingly popular due to both economical advantages as well as environmental concerns. Casing advancement systems are often used to drill the holes through the overburden, keeping the holes open during installation of the heat exchange system and minimizing the impact on surrounding structures.