Monticello Uranium Disposal Cell, Utah

A 90-acre vegetated disposal mound south of the town of Monticello. The federal government's Defense Plant Corporation built a uranium and vanadium mill here in 1942 to produce material for the Manhattan Project. Milling continued until 1960. In 1975 the mill buildings were demolished and buried, and the site was revegitated. As at a number of other former uranium mill sites, the sandy piles of tailings left from the mill were used for construction projects around town over the years, leading to higher levels of radioactivity in these places. Over the 1980s, 424 properties, including sidewalks, sheds and patios built with the tailings were demolished and their materials buried at the former mill site. The material is covered by a 5.5 foot thick soil layer, which serves as a sponge, holding moisture from rain. A leachate collection system removes water from the bottom of the cell, and pumps it to an evaporation basin.