A system and method for dewatering a subsurface vault housing a portion of a pipeline is provided. The dewatering system includes a fluid inlet pipe adapted for fluidly communicating with the pipeline and redirecting fluid being transported by the pipeline to a fluid pump system. The fluid pump system includes a pump capable of being operated solely by the redirected fluid for removing fluids, such as water, from within the subsurface vault. A fluid outlet pipe in fluid communication with the fluid pump system returns fluid not used to operate the fluid pump system back to the pipeline for being transported downstream from the dewatering system. A liquid level sensor is used for generating and transmitting a signal to a valve when the water within the subsurface vault exceeds a predetermined level for permitting the redirected fluid to flow to the fluid pump system.