Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) evaluation of Rockdrain and a conventional tunnel drainage system

Water leakage into rock tunnels can often cause problems. The water pressure in combination with cracks in the rock allow water to leak into the tunnels and causing problems such as icicles, water in the tunnels, significant power consumption for pumping of water, etc. When injection is not sufficient to fulfill the function requirements of the tunnel, additional external drainage systems have to be used to drain the water from the roof and walls. This drainage is usually carried out by mounting sheets of extruded polyethylene foam, which is affixed with rock bolts onto the rock surface and finally covered with shotcrete. This drainage method is relatively labor-intensive, material and space consuming. Rockdrain is a new drainage system based on a new drainage principle. Drainage channels are formed in a water permeable shotcrete layer. The permeable shotcrete layer is then covered with a less permeable shotcrete layer (Solbruk T) which is specially designed for the Rockdrain application. The formed piping lattice in the permeable shotcrete traps the water inside the shotcrete layer and lead the water away from the tunnel. The Rockdrain system is intended to simplify construction and improve performance through a more solid construction with fewer and less sensitive technical components. The main application for the Rockdrain system is in different tunnels and especially road and train tunnels. Many different aspects of the drainage system have to be explored in a research project. The main research project was thus divided in three sub-projects; Material and function tests, Fire tests and “Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) analysis of the Rockdrain system”. This report covers the later LCA and LCC analysis. In this part, which is performed by IVL Swedish Environmental Research Institute, the energy, resource, and environmental aspects are analyzed along with the economic aspects. To be able to evaluate the results, the new Rockdrain system is compared with a conventional drainage system of today. The results look very promising for the Rockdrain system. A cost reduction of 55 percent and an energy reduction of 43 percent when switching from a conventional drainage system to Rockdrain are some of the results. This report is only available in English.