Balanced pressure earth drilling rig - producing negligible emission of gaseous toxic pollutants

摘要

In soil investigations to ascertain the nature of possibly toxic deposits, there is risk of emission of potentially dangerous vapours and aerosols (e.g. dioxins and furans) into the external environment. This invention provides a procedure and apparatus for sampling a bore hole (8) without allowing such release, involving sealing the bore hole outlet to a chamber pressurised with an inert gas. Prior to arrival of the drilling rig, a flanged well-head fitting (41/42) is driven into the ground at the proposed site. The mobile rig (1) is assembled around a combined road-going/rough-terrain vehicle (2) which is parked over the pre-sunk head fitting (42) and coupled to the fitting via a mating flange (32) on the floor of the rig pressure chamber. The drill tower (4) is arranged so that the drill string (45) passes through a mechanical seal (34) in the chamber ceiling, and enters the ground via the coupled head fitting (42). The pressurised chamber can be entered by operators, wearing suitable breathing apparatus, via air lock (51), but, drill changing, sampling, and even analytical procedures can all be performed by operators, outside of the chamber, working through glove boxes. The chamber is protected by explosion relief panels. Nitrogen gas is suitable for pressurising the chamber. USE/ADVANTAGE - Landfill waste disposal monitoring. Avoidance of contaminating drill operators and the external environment.