French to English Tech/Engineering Construction / Civil Engineering

Context: scope of health and safety assignment on a construction site:

Cette mission concerne la phase de conception, d'étude et *d'élaboration* du projet ainsi que la phase de réalisation de l'ouvrage

The problem is that in English 'conception', 'étude' and 'élaboration' are often all three translated as 'design'.

I've come up with:
This assignment concerns the schematic design, design and *prepapartory* phases of the project as well as the execution phase of the works.