Built with Muscle and Muck

Built with Muscle and Muck. . The largest hydraulically filled dam in the world, Fort Peck Dan was made from a slurry of sand, silt, clay, and gravel dredged from the Missouri River. , Nearly four miles long, the dam needed over 125 million cubic yards of material-enough to fill more than 12 million dump trucks. Huge dredge boats sucked a watery mixture of sediment from the bottom of the river and pumped it to the dam through long pipelines. As the material settled out of the water, the core of Fort Peck Dam solidified. , Heart of Steel Although the dam looks like just a mound of dirt, it was engineered to withstand the pressure of 130-mile-long Fort Peck Lake. Deep inside, a 35-million-pound steel wall prevents water from seeping underneath the dam. This wall was pounded deep into the shale bedrock below the dam and surrounded by an impervious clay core. The force of the water helps stabilize the dam. , In August 1935, 200 workers set a world record by driving steel plates more than 160 feet into the bedrock to support the earthen dam. All together, these steel walls stretch nearly two and a half miles long.