Some time next month, when the tiles are finally laid, the furniture installed and the piles of dirt transformed into landscaped gardens and lawns, Rockeville's newest hospital -- the Psychiatric Institute of Montgomery County -- will be ready to accept its first patients. And yet the controversy that has surrounded the hospital for more than a decade will still be alive.

In other communities, the issue might be popular prejudice against mental institutions. But, in Montgomery, concern centers on cost and accessibility. i

The profit-making hospital, part of a national chain of psychiatric facilities, stands inside the county's Medical Center, established to encourage "health care services at lower cost," and got special financial breaks. When PIMC earlier this year proposed rates as high as $418 per day -- the steepest ever sought by a private psychiatric hospital in Maryland, according to state health officials -- the request rekindled concern that the country was getting a rich man's preserve, not the widely accessible hospital that it had sought.

Last week the Mayland Health Services Cost Review Commission rejected PIMC's rates request, substituting a scale 30 percent lower devised by the commission's staff. The ruling heartened PIMC's critics -- who include a number of county council members and local psychiatrists as well as the parents of children under treatment for mental problems -- but it is strongly opposed by officials of the hospital.

"Open up a facility and go bankrupt. That's what the cost review commission has asked us to do," complained PIMC administrator Donald Silver, who says the hospital will seek a court injuction to allow it to open with its own rates pending public hearings. That would be the first suit by a new hospital in the commission's seven-year exsistence, a commission lawyer said.

The hospital is a subsidiary of the Psychiatric Institute of America (PIA), a Delaware-based private corporation that owns or controls close to a dozen similar facilities around the country, including one in the Dstrict of Columbia and another in Loudoun County, Va.

The group first sounded out Montgomery in the late 1960s and by 1971 had received certification for the project. But in the following years, the County Council sniped at it, arguing that a private, profit-making hospital did not belong in a publicly sponsored medical center.

Nonetheless, PIMC gained the full approval of state and other county agencies, winning authorization to issue 44.2 million of low-interest, tax-free Industrial Revenue Bonds with the understanding that resulting savings would be passed on to patients. Construction finally began late in 1979.

Interest income that revenue bond holders receive is exempt from Maryland and federal tax. This allows the bond issuer to pay a lower rate of interest and realize major savings. The county government authorizes issuance of revenue bonds as a means of attracting new industry to Montgomery.

Memory of the bonds helped stir up emotions this year when PIMC finally propsed its rates. The proposal surprised even county health planners who has worked with PIMC since the beginning and expected rates around $250 or $260.

Adolescents in the hospital's "closed unit," or sealed-off ward, would pay $418 per day under PIMC's scheme, adolescents in open units, $382, and adults, $308. These rates would cover room and board only, with doctors' fees, medication, lab tests and other servies costing extra. Outpatient visits were proposed to cost $102 each.

Those figures were based on a financial scenario that would give the hospital's shareholders an average 20 percent yearly return on their capital over five years and channel 6 percent of hospital revenues to the parent corporation, PIA, as fees for managerial and administrative services.

The commisssion marked PIMC's in-patient rates down to $294, $251 and $204 respectively, and set outpatient visits at $80. It raised a wide range of technical objections to PIMC's financial scenario, saying projected adminstrative cost were too high and occupancy rates too low.

Hospital officials have countered the criticism with a public relations campaign in Montgomery County, sending its affable medical director, Dr. John Meeks, to call on newpaper offices and mailing "Dear Colleague" letters to county physicians to rebut what is seen as misinformed critcism of the $6-million facility.

"We were surprised too when we sat down and looked at what costs woudl be," said Meeks. "We'd all like to have them lower." However, he continued, the hospital has been built from scratch and will offer emergency and community outreach services. Meeks called it a "state of the art" facility with highly qualified doctors and medical staff looking after extremely sick patients. "If we're going to have these specialty services, they're going to be expensive," he concluded.