(Nati Harnik/AP)

OMAHA, Neb. _ We're less than a week away from the head of pool construction for the U.S. Swim Trials saying, "Fill 'er up!"

John Ireland of Myrtha Pools says construction is ahead of schedule at the CenturyLink Center, which will be hosting its third trials June 26-July 3. The shells of the competition and warmup pools are up. Welders and plumbers were working Tuesday on the frame and piping.

The Omaha Fire Department will assist with pouring in a combined 1.7 million gallons of water into the pools beginning Monday. It'll take up to 10 hours to fill each pool.

The work is moving along more quickly than in 2008 and 2012 largely because Myrtha is using a prefabricated steel foundation with pre-drilled holes rather than precast concrete blocks for the base.

Another difference from the previous trials is that the competition pool is 26 meters wide instead of 25. That will allow for Lanes 0 and 9 to be bordered by ropes rather than by walls, which will make for calmer waters for swimmers in the outside lanes during preliminaries. The water recirculation system also minimizes currents, creating optimal conditions for Michael Phelps, Missy Franklin and the other competitors to turn in fast times.

"It's not about aiding the athletes," Ireland said. "It's about getting rid of anything that might hinder them."

Ireland said 34 Myrtha employees and 50-60 local workers in addition to CenturyLink Center staff are on a work crew representing seven countries. Myrtha also is the pool manufacturer for the Olympics in Rio de Janeiro.

The Omaha pools were made in Italy, shipped in pieces in containers from Genoa to New York and sent from there to Nebraska.

When the trials end, the pools will go their separate ways. A club in West Fargo, North Dakota, purchased the competition pool. A swimming foundation in Santa Ynez , California, bought the warmup pool.