The Army Corps of Engineers has awarded an $898,000 contract for the first construction work on the Little Dell Dam east of Salt Lake City.

The contract to build a core trench at the base of the dam site was awarded to Harper Contracting of Salt Lake City, which will begin the work in the middle of May, said Robert Smith, the corps' resident engineer.The 1,800-foot wide trench will provide "engineering data to refine the design based on actual field conditions" and for detailed examination of the dam base, Smith said.

The $50 million, 224-foot-high earthen structure will be built on Little Dell Creek about a mile and a half above the existing Mountain Dell Dam in Parley's Canyon.

The Little Dell Dam, eight miles east of Salt Lake, is scheduled to be completed in September 1991 and will create a reservoir nearly a mile and a half long. Its primary purpose is flood control for waters that eventually feed along 21st South in Salt Lake.

The contract for construction of the dam itself will be awarded in March 1989, Smith said.

The core trench will be about 80 feet wide and, in some locations, reach 60 feet in depth. Smith said earth from the trench will be placed in a test fill to determine the best methods for compacting it during dam construction.

The dam is being jointly funded by the federal government, Salt Lake City and Salt Lake County. Smith said there currently are no plans to develop the reservoir for recreation, although city, county or state governments may seek to do so later.