Waste transfer barge
A waste transfer barge was a type of ship used by the Federation to transfer waste.

Somewhere between 2374 and 2376 the EMH Mark I was reconfigured to scrub plasma conduits on waste transfer barges, much to the annoyance of their creator Dr. Lewis Zimmerman, who had created them in his likeness. By 2377, some EMHs had been transferred off the barges to perform other menial tasks. ()

See also 
 Garbage barge
 Garbage scow
Spacecraft classifications