The high cost of underground work needed to install geothermal tubing is inspiring some installers to develop cheaper alternatives. One unusual machine, called a SpiderPlow, is gaining traction in Canada. + image Illustration: Spiderplow Services Inc. A crawler rig, anchored 6 ft into the ground, reels a special cable that pulls the plow, which can handle 24-in.-dia. pipe and 9.5-ft depths. Related Links: As More Buildings Go Geothermal, Project Teams Are Thinking Outside the Borehole Union Jumps On Geothermal Bandwagon Jim Bererton, who heads consulting engineer Stantec’s sustainability practice in Calgary, Alberta, brought in the SpiderPlow for a Walmart store
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.