Waste previously fly-tipped at the site had to be cleared away before investigation and preparation work could begin. The company also plans to improve the way the site looks.
Rigmuir will be used to dispose of South Lanarkshires residual waste, alongside Viridors other engineered Scottish landfill sites.
Site project manager Leon Brackstone said: Were taking scrupulous care that we comply with conditions agreed by the council.
Preparations for the site liaison group are underway and contact is being made with a number of local stakeholders.