Labor Department workers here will be able to take up to two years' leave -- with the guarantee that their job will be held for them -- for child-rearing purposes.

The new provision, believed to be a first for government, applies to both men and women parents, to their natural or adopted children, and to eligible employes whether married or single.

The special leave policy is part of a new three-year contract between the department and a local of the American Federation of Government Employees that will be formally announced today. The AFL-CIO union has exclusive bargaining rights for 6,500 of the department's 9,000 headquarters staffers here. The agreements cover all but management and supervisory personnel.

Talks on the ground-breaking contract began in January and lasted until Friday, when agreement was reached with the help of an outside arbitrator, Rolf Valtin. Valtin, considered one of the top people in his field, is a former president of the National Academy of Arbitrators He was paid $15,000 for his services, with the cost being split between the government and Local 12 of the AFGE union.

Under the new agreement, employes can take off up to two years for child-rearing purposes. Women can use a combination of sick of maternity leave annual leave and leave without pay. Men can take annual or LWOP. All are guaranteed their old or a comparable job at their current grade, and pay raises while they are on leave.

Other provisions of the new agreement, which could set a pattern in other federal agencies, include:

Negotiated guarantees to permit workers to use flexitime (set-your-own hours) to provide extended service hours to the public, and allow employes in some units to schedule regular four-day workweeks.

A pledge by the Labor Department that one of every 10 new or vacant professional-level jobs will be earmarked for lower-level workers in technical and clerical fields. Those employes will be given formal and one-the-job training leading to higher-paying jobs in professional categories.

Agreement that employes may refuse to work if they believe they are in imminent danger because of unsafe, or unhealthy conditions.

Expanded grievance procedures that will include regular grievance machinery, or an "expedited" system that will utilize the services of five arbitrators already mutually selected by the department and the union.

A health and safety committee split 50-50 between labor and management. Under the new contract, OSHA inspections may be ordered if half of the committee suspects that there is a health or safety hazard.