Twenty-two years old and fed up, she lounged in denim shorts on the hood of her new yellow chevy in the parking lot outside the Merrifield postal center. She wanted to catch a few minutes of sun before 3:30 p.m., time for her shift sorting letters inside the huge mail factory.

She twisted her long brown hair into braids with angry motions as she talked about her job - the machines, the noise, the monotony. She spat four-letter words.

"Only reason I work here is I need the money," she said. She has a 5-year-old son to support and the Chevrolet to pay for, the fourth new car she has owned in her young life.

The worst thing about the job, she said, is that you can't count on getting away from it after working your basic eight hours.

The postal service, like many other idustrial employers across the nation has mandatory overtime contract with its employees. They can be required to work overtime (at time-and-a-half pay) whether they want to or not, up to two extra hours a day, six days a week (and more during the weeks before Christmas and for special emergencies).

In the predominantly office-bound, white collar world of Washington, the plant provides a reminder of the frustrations and monotony of life in factory-type setting during an era when the popular rhetoric speaks of the "quality of life," and "meaningful work."

For many workers at Merrifield, their personal quest for fulfilment takes place outside of work, and their numerous complaints about their jobs are focused around the mandatory overtime. They say they would rather have time off than money.

Labor union officials and scholars say this is a growing phenomenon.

"The idea is . . . a worker wants to call his life his own, and not have to respond to the employer's call at every monent," said Paul Wagner of the community action staff of the United Auto Workers. "More time off is one of the most salient demands of workers now."

He said that the industrial worker, often regimented in one spot for most of his or her eight hours, "does not have the latitude that some office workers have in using his time for any other purpose during working hours."

Working at Merrifield "is not much of a life," said David Acree, 24, who sorts the mail on the 4 a.m. to 12:30 p.m. shift a Merrifield, which some employees say often bears the brunt of the overtime burden. "All it is making money."

Acree and the bitter young woman are tow of 1,072 employees who process Northern Virginia mail in three main shifts on the 10-acre work floor at Merrifield. Most of them are under 30, according to their manager, and they have a high rate of tunover.(About 400 more employees work in offices on upper floors in maintenance or in other capacities at the plant.)

The Merrifield facility, opened in 1972, is a "showplace" for the modern postal service, according to spokesman. Under rows of overhead lights that veer like tracks into the distance, the employees stand a conveyor belts piled with letters or sit punching a key at the big letter sorting machines, some wearing headphones against the constant vibrating drone. The sorting machines process 60 letters a minute.

There are rows of carts, stacks of the familiar mail sacks, row after row of cubbyholes for sorted letters. Much of the work is still done by humans, using their eyes and hands and heads full of memorized information, such as route numbers. The building is air-conditioned.

Dissatisfaction with their work manifests itself particularily in resentment against forced overtime. Union leaders and some employees say it is the biggest source of complaints at the facility and a growing morale problem.

Only 93 employees, or fewer than 10 per cent of those who process mail at Merrifield, have put their names on the voluntary overtime list, accoring to management figures.

Acree said he typically is required to work eight overtime hours a week and sometimes works 10 hours a day, six days a week. He makes about $6.25 an hour normally, he said, and close to $10 pe r overtime hour.

Several others, who did not want their names used, gave similar estimates of their overtime. Some said they didn't mind working extra hours on occasion, but objected to their lack of control over the timing. They said those who refused to work overtime upon demand had to present written evidence from a doctor that they were unable to work, or they were suspended and after three refusals, fired.

The employees said they want the Postal Service to hire more workers and cut down on the required overtime, or return to purely voluntary overtime such as has existed at times in the past.

James Banks, president of the local workers union, said that overtime had been the subject of complaints periodically since the plant opened five ago and that the situation had improved somewhat after the plant added some new employees. "It is a years ago and that the situation had improved somewhat after the plant morale problem," he said. "But the union-oriented anyway. So our union is practically ineffective." He said slightly more than half the Merrifield employees belong to the union.

Spokesmen for the U.S. Postal Service nationwide and for the management at Merrifield say that the particular to hire extra employees full time when they will be needed only during periods that are occasional and often unpredictable.

Like employers in other industries, they have found it less costly to pay overtime than to hire new full-time workers, with all the training, and health, vacation and other benefits that they require.

They say the overtime requirements are balanced by generous wages and benefits and a no lay-off clause.

"The overtime is higher at Merrifield than I would like," said manager G.T. Bond Jr., who started as a mail carrier with the post office 32 years ago and worked his way up through the ranks. He said his figures indicate his employees worked an average of just under 10 overtime hours each per month during February and March, though some employees bear more of it than others because they have the required skills.

Bond said the overtime requirements increased temporarily wheMerrifield's jurisdiction was expanded a year ago, causing a drastic increase in its workload.

More generally, he said, "We're just not like other factories. We can't say we're going to produce 50 washing machines today. It's the public that decides what we do on any given day. We can't predict when people are going to mail. So we need a lot of flexibility, in what work our employees do and when they do it."

He said a light week might require only 100 or 150 man-hours of overtime while a heavy week would take 600 or 700 overtime hours.

Putting overtime on a voluntary basis is not effective and could even be wasteful, he said, "because those who volunteer are not necessarily in an area where we need them."

"Everybody has something to complain about," said one veteran postal worker, formerly a clerk, now a supervisor at Merrifield. "I complain myself. When we're busy, I can't get leave to go to the doctor. We had Easter, Jewidh Passover. Now it's tax time. You can bet the customers complain if their letters aren't delivered on time."

She said that from her crew of 42, that day, she had asked for eight hours of overtime. "That's four clerks to work two hours each. Not one volunteered, so I had to make it mandatory."

Christmas time is a special agony, according to one woman clerk who is married and has three children. "My husband and I both work. We try to split up our chores. But when I'm on overtime, my husband ends up with all the work, the cooking, the dinner, the washing."

She said it takes her 30 to 45 minutes to drive between home and work. "Sometimes they call in the middle of the night and say, 'We need you in two hours early. That's 2 a.m."

In December, when the postal service can require even more overtime than normally, she said, "I neglect my home completely. It's as though there's no wife here at all."

She said she had worked 12 hours a day, six days a week for most of December during each of the five years she has worked at Merrifield.

Bond, who became manager of Merrifield a year ago, said that management has the right to require employee to work up to seven days a week, 12 hours a day during December, and that he would invoke tha tif he thought it necessary."But so far, only one employee has worked that much and he volunteered because he needed the money."

Bond added that last Christmas was especially severe because of the United Parcel Service strike.

He said that about 14 or 15 employees in the plant quit each month, and that makes it necessary to train replacements, and that means overtime for others to make up the drop in productivity.

One young employee who hopes to escape someday from her Merrifield job said she thinks the plant's sheer "bigness" is the problem. "My father has been with the post office for 32 years and he told me not to take a job at Merrifield," she said. "But I needed the money."

"I think things are OK at the smaller post offices. But here, it's all pressure, pressure, production, production . . . I'm going to save up and after I get this paid for" - she tapped her late model Mustang - "I'm going to get some training in something else."

David Acee has already taken steps. He had dropped out of Northern Virginia Community College three years ago to earn somemoney at Merrifield and figure out what he wants to do with his life. Now he has decided to quit his job at the end of the month and go back to school. He wants to major in music, he said. "At least it will be a bit of a life."