Airlocks for conveying material, hydro excavation vacuum apparatus having airlocks, and methods for hydro excavating a site

A hydro excavation vacuum apparatus for excavating earthen material comprising:

• a wand for directing pressurized water toward earthen material to cut the earthen material at an excavation site;
• a vacuum pump for removing cut earthen material and water from the excavation site in an airstream, the vacuum pump being a positive displacement pump;
• a separation vessel for removing cut earthen material and water from the airstream;
• a conduit for conveying water and cut earthen material from the excavation site to the separation vessel, the conduit having a diameter D1;
• and
• an airlock that receives material from the separation vessel and discharges the material through an airlock outlet, the airlock comprising vanes with pockets and pocket sidewalls that contact and rotate with the vanes, the pockets being disposed between adjacent vanes and the pocket sidewalls, the vanes being sized to receive particles with the diameter D1 or greater, the airlock further comprising a housing, the housing having a first sidewall, a second sidewall, and an outer circular wall that extends from the first sidewall to the second sidewall, wherein the airlock outlet extends through the outer circular wall and tapers outwardly from a vertex toward at least one sidewall, and wherein each of the vanes of the airlock comprises a distal end located proximate the outer circular wall.