Because most of his task involved construction, Marshall worked in cooperation with the head of the Corps of Engineers Construction Division, Major General Thomas M. Robbins, and his deputy, Colonel Leslie Groves.
Xa que gran parte do proxecto involucraba tarefas de construción, Marshall traballou en cooperación co xefe da División de Construción do Corpo de Enxeñeiros, o xeneral maior Thomas M. Robbins, e co seu subxefe, o coronel Leslie Groves.