A secret contract was awarded to M. W. Kellogg for engineering studies in July 1941. This included the design and construction of a ten-stage pilot gaseous diffusion plant. On 14 December 1942, the Manhattan District, the US Army component of the Manhattan Project, as the effort to develop an atomic bomb became known, contracted Kellogg to design, build and operate a full-scale production plant. Unusually, the contract did not require any guarantees from Kellogg that it could actually accomplish this task. Because the scope of the project was not well defined, Kellogg and the Manhattan District agreed to defer any financial details to a later, cost-plus contract, which was executed in April 1944. Kellogg was then paid $2.5 million.