Population increments in big cities have resulted by problems of people such as transportation, health, service and drinkable water necessities etc... In order to meet utility water requirements, underground tunnels are sometimes burrowed for transmitting water from far away resources. One of them was the Ayazaga conduit tunnel in Istanbul excavated by conventional tunnelling in a rock media from poor to extremely poor formation. After excavating and properly supporting media, a compact grout application is performed before a "consolidation grout phase (CGP)", that is subject of this paper. In CGP, A set of holes for every 3 m approximately, which filled out by cement injection, were drilled from pipe inside in to the compaction grout shell first and support shell in second till going through 0.5m in formation third. An undergraduate thesis examining this application and process, focused on a portion of current tunnel from the CGP point of view. Nevertheless, rock parameters on the tunnel face were recorded by side geologists. When these data and amount of the injected CGP are analyzed, some remarkable relationship can be seen between formation and amount of CGP injections that may help practitioners to predict injection levels and cost evaluation in the similar formations. © 2013 Taylor & Francis Group.