BC Hydro is an electric utility located in mountainous terrain with a broad range of valuable assets built in a variety of rock masses ranging from massive granite to weak shale. Examples of significant rock structures that are vital to BC Hydro’s operations include dam foundations, underground powerhouses, landslides, power and diversion tunnels, open cut excavations, canals, and foundations for powerhouses, penstocks, and transmission towers. Rock engineering processes include site characterization, monitoring, modeling and interpretation, design, construction, long-term surveillance and maintenance. These processes typically span decades and even a relatively young utility like BC Hydro maintains facilities that are almost 100 years old. With a significant rock-related workload, BC Hydro is well-experienced with a variety of rock engineering consultants. The paper explores this experience and presents characteristics of a great rock engineering consultant, from a hydroelectric utility client’s perspective.
1 HYDRO ROCK ASSETS
BC Hydro is a public owned electric utility serving customers in British Columbia, Canada. It has over 10 GW of generating capacity of which about 90% is hydroelectric, over 18,000 km of 60 to 500 kV transmission lines and substations that are managed and operated by BC Transmission Corporation, and over 55,000 km of distribution lines and substations. British Columbia has a geographic area of 95 million hectares and is approximately 1,400 km long and 650 km wide, with very diverse topography (Fig. 1). The western, coastal areas are mountainous with rainforests, fjords and glaciers. Inland and mid-province, there are dry, desert-like valleys and plateaus Climate ranges from temperate in the southern coastal area with mean monthly temperature typically ranging from 18 to 4°C between summer and winter months, to severe in the northeast with seasonal mean monthly temperatures ranging from about 16 to -15°C. Precipitation also varies greatly, often over short distances due to orthographic effects.