A branch drain accepting waste products delivered to it vertically, by gravity, from one or more similar but usually smaller fixtures, and conducting them horizontally to the primary disposal drain.
When the Minuteman III retires, the silos and launch facilities at Malmstrom Air Force Base in Montana, which oversees 150 nuclear ICBMs scattered across a 13,800 square miles, will have been buried for 70 years.
The first successful test followed on 21 August 1957; the R-7 flew over 6,000 km (3,700 mi) and became the world's first ICBM. The first strategic-missile unit became operational on 9 February 1959 at Plesetsk in north-west Russia.