Minidirectional Drilling for Installation of Underground Electrical Conduit

The Salt River Project (SRP), located in Phoenix, Ariz., uses two different construction techniques to install conduit for new underground electrical systems in the Phoenix metropolitan area: open-trench cutting by conventional backhoes or wheel trenchers, and trenchless excavation techniques with minidirectional drilling machines and trenchless technology. This paper presents the results of research conducted to determine the comparative installation costs of conduit for SRP's underground electrical distribution, comparing the cost of conventional open trenching with minidirectional drilling. The study compared cost information that will aid SRP designers in optimizing the selection of site-specific underground electrical-conduit placement techniques. The research considered economies of scale, terrain, soil types, materials, and various common configurations of electrical conduit systems. In the years ahead, utility companies around the country may investigate the feasibility of minidirectional drilling to replace open trenching, especially in congested areas where the maintenance of good public relations is important. The analysis presented in this paper may provide a basis of comparison for other utility companies.