Airport Management reported an aircraft landed with snow removal equipment on the runway. Reportedly; the aircraft was not on the proper frequency.

Narrative

Report provided by airport management; operations; and maintenance personnel. Aircraft X landed runway XX without announcing on CTAF while we had snow removal equipment on runway XY/XX. Two vehicles were on the runway at this time. Tower informed us that the aircraft diverted from nearby ZZZ airport. At XA07 the pilot announced on Tower frequency; that they were on the RNAV RWY XX; yet it was garbled and hard to hear. They did not announce how far out they were and did not announce on CTAF upon landing. Nobody on the snow team heard the announcement. ZZZ Approach never let us know we had an aircraft inbound. Tower was not open yet; but for safety; Tower got ahold of the pilot; on tower frequency; on short final and told the pilot to go around at least twice; and informed the pilot that the airport had snow equipment on the runway. The pilot claimed to see no equipment on Runway XY/XX and proceeded to land. Both vehicles reported that the aircraft flew approximately 30 feet above their vehicles.