Site preparation for reconstruction of the failed Trial Lake dike, near Mirror Lake in the Uintas, could begin as early as this fall.

Directors of the Central Utah Water Conservancy District have voted to advertise and retain an engineering firm to design and develop specifications for the dike. The directors, at a meeting last week, also gave the district permission to advertise for bids on the excavation and site preparation job.Don Christiansen, CUP general manager, said he will ask the board in September to award the bid for site preparation.

An earthen dike along the east of Trial Lake reservoir, which historically held 1,600 acre-feet of water, failed in 1985, after the base of the dike eroded - possibly from rodents burrowing into its foundation.

It is one of 15 reservoirs to be upgraded in conjunction with the construction of the Jordanelle Dam and reservoir, according to a U.S. Bureau of Reclamation proposal.

CUP's chief engineer Sheldon Talbot said the rehabilitation project should cost about $350,000. CUP will pay for the project until federal money is available in 1992 and 1993.

Christiansen said the project may end up costing more than $350,000 because CUP will not sacrifice safety in favor of a less expensive structure.

"If we were to do anything to shortcut this and there were a failure, we would have no way to explain it," he said.

Geologic and design studies have concluded that the dam and dike could be safely reconstructed at the site. A state dam safety representative has recommended that the failed dike be removed, the material stockpiled, and the dike rebuilt using most of the same material.