Surplus Depot Z15 was a Federation surplus depot operated by the Zakdorn, located on and in orbit of Qualor II in Sector 213. The facility was responsible for salvaging useful components from decommissioned vessels before storing them in the depot. In the 2360s, its quartermaster was Klim Dokachin.
In 2368, the USS Enterprise-D traveled to Qualor II as part of its investigation of debris linked to the Vulcan starship T'Pau, in an attempt to determine the fate of the vessel. Upon arriving, it was discovered that the T'Pau – previously docked at section 18-Gamma-12 – was missing, taken by forces unknown. The T'Pau's navigational deflector, source of the debris, had been routed to the USS Tripoli, a holding vessel for the depot located at the outer edge of the shipyard, at section 12-Delta-4. It emerged that the Tripoli too was missing, leading to the conclusion that another party was intercepting shipments bound for the Tripoli and routing them elsewhere. Commander Riker powered down the Enterprise and lay in wait for the smugglers.
When the smuggler vessel arrived, the Enterprise attempted to hail it, but the exchange of fire that resulted, along with the vessel's large weapons cache, caused it to explode. It was later linked to a Ferengi arms trader, Omag, who had taken the T'Pau from the depot and sold it to a Barolian intermediary to be used in an abortive invasion of Vulcan by the Romulans. (TNG: "Unification I", "Unification II")