Surplus Depot Z15 is a Federation ship grave yard operated by the Zakdorn. Klim Dokachin was in charge in the 2360s. The facility orbits Qualor II and is responsible for salvaging useful components from decomissioned vessels before storing them in the depot.
The USS Enterprise-D's investigation of missing, decommissioned, Vulcan vessels, led the ship to Qualor II in an attempt to locate the missing vessels. Upon arriving, it had been identified that salvaged debris from a Vulcan ship, belonged to the T'Pau, a vessel that had been stored at Depot Z15, but later removed by unknown forces.
The starship USS Tripoli was another vessel identified as missing from it's position in Depot Z15. As part of the investigation, Commander Riker powered down the Enterprise and lay in wait for the USS Tripoli, or whatever vessel was receiving the Depot Z15's supply shipments.
Upon the identification of a smuggler vessel, the USS Enterprise-D attempted to stop and search the ship, but the smuggler vessel's large weapons supplies caused the vessel to explode when fired upon. It was later identified as belonging to a Ferengi smuggler, Omag. (TNG: "Unification I & II")
- The Star Trek Encyclopedia refers to the depot as Surplus Depot Zed-15. In the script, it is spelled out as Surplus Depot Zed-One-Five once.