Health chiefs meet today to discuss proposals which will see the closure of the Fermoy Unit in King's Lynn.
The Norfolk and Suffolk Foundation Trust, which runs the unit and the West Norfolk Clinical Commissioning Group, overseeing health care in the area, have already agreed the move.
They want to replace the Fermoy, at the Queen Elizabeth Hospital, with a new 16-bed unit at Chatterton House, on Goodwins Road.
Today board members from both organisations are being asked to agree for work to begin on what officials call the adult acute pathway transformation.
In West Norfolk, the CCG is meeting at King's Lynn Town Hall at 9.30am. The meeting is open to the public.
MORE - Report to today's clinical commissioning group meetingThe £4m scheme involves refurbishing two currently unused wards at Chatterton House and building a corridor to connect them.
The foundation trust says it will offer state-of-the-art, en-suite single room facilities for men and women with a variety of mental health conditions, such as depression and bipolar disorder.
Its chief executive, Michael Scott, said: 'We are very excited about these proposals and think that together we have found the best solution for redeveloping and improving our west Norfolk adult acute services, and ensuring their sustainability into the future.
'This will see significant financial investment into new and existing services, as well as more effective ways of working to improve the experience of people accessing our care.'
Pauline Davies, NSFT's west Norfolk locality manager said: 'Once the work is complete, we will be able to offer truly integrated adult mental health services from the site. People who have been discharged following inpatient care, would be able to return to the same building to access community services.
'The significant refurbishment would offer us an excellent opportunity not only to improve the facilities from which we provide care, but also introduce to additional services for the benefit of patients and their families.'
But there were protests when the proposals first became public last year, with campaigners calling for the unit to be saved. The trust said at the time there were no plans to close it.
MORE - Campaigners call for Fermoy Unit to stay open
If plans are agreed today, the next step will be to liaise with service users, carers and partners to finalise the plans.
Work on the new unit is expected to begin by next December.
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