A device used to manage the movement of surface water into and out of an attenuation facility. Drainage which runs through pipework installed to a fall, and not therefore under pressure. Water that is below the surface of ground in the saturation zone. Will not allow water to pass though it.
Examine your crawlspace from both the inside and outside and find all holes and entrances into the space. If your crawlspace is reasonably dark, going inside, turning off the light and looking for sunlight coming in from outside is a great way to do this. Seal the holes with expanding foam or caulk.
Waterproofing a crawlspace is defined as the resistance of the passage of water under hydrostatic pressure (ground water) through the foundation and accumulating in the crawlspace.