Most important design — Build comparisons in three underground projects in Antioquia, Colombia

This article will try to show the most important design — build comparisons in three underground projects built in Antioquia, Colombia, during the last 15 years; the projects are called: Playas hydroelectric project, Riogrande II hydroelectric project and recently and still under construction Porce II hydroelectric project. Several aspects will be analyzed such as reinforcement installation, excavation procedures, geology and costs of construction, doing special emphasis on the recent construction of the Porce II underground works. As an important conclusion it could be said that the constructions in general were developed under good rock conditions and these help projects mentioned to be cheaper and more attractive than others; additionally it is very important to know these experiences in the contracts during construction, in order to be ready in the future for similar works.