Wellesley College's 280 kitchen, custodial and construction employees will go on strike Friday morning unless there is a dramatic breakthrough in today's scheduled contract negotiations, union officials said yesterday.

The college has offered a three-year contract with one raise of three and one-half percent the first year and two succeeding raises of three percent each, but the Independent Maintenance and Service Workers of America are asking for a two-year pact with "six or seven percent each year," said union President Richard A. Russell.

Pension plans and a mandatory, unpaid five-week layoff between academic terms are also at issue for the union, whose members earn between $6.72 and $11.58 an hour, Russell said.

Today's talks are the last scheduled before the midnight Thursday deadline for what would be the first-ever strike at Wellesley, he said.

Dean of the College Maude Chaplin and Vice President of Business Affairs Burton Sontenstein refused comment yesterday.

The prospect of a strike by the workers, whose old contract expired July 1, has alarmed students, said College Government President Jody Gottlieb. But she said "students were quite supportive" when union representatives spoke at a meeting of the government Monday night.

Wellesley, a small city about 12 miles west of Boston, has no inexpensive or moderately-priced restaurants within walking distance, and "there will be no food" on campus if the union walks off, said Gottlieb.

"[The Wellesley Administration] seems to have made no provisions in case of a strike," added Louise Dean Williams, news editor of the Wellesley News. "They are so confident of making a settlement, they have not said a word."

Gottlieb said a college official had speculated the students would be reimbursed for the cost of missed college meals.