Abstract: The invention relates to a system and method for separating, and safely monitoring and sampling flow back fluid returns from coiled tubing operations in oil and natural gas wells. The system comprises a flow back tank; one or more gas diffusers; one or more shale shakers; and a chute, which diverts flow from the gas diffusers to a sampling site positioned near the perimeter of the flow back tank. The system also has a volume level indicator on or near the perimeter of the flow back tank. The method comprises piping fluid returns from a wellbore, separating the trapped gases from the fluid returns, directing the degassed fluids to a shale shaker to separate the solids and directing the separated solids and liquids into separate tanks for analysis and reconditioning, if necessary. Cleaned liquids may be recirculated back to the wellbore.