Developers have completed site cleanup efforts at the location a resort casino on the Mystic River in Everett, which previously housed chemical companies for more than 100 years.

Encore Boston Harbor reported Wednesday night that work that began more than 18 months ago involved moving nearly a million tons of soil and sediment on land and water and cost $68 million in private funds, not the $30 million previously estimated for cleanup work on the 33-acre site. The company plans to spend $14 million on “landscaping and beautifying” a 6-acre park in front of the casino.

The cleanup costs, along with the addition of restaurants and a change in the size of a casino ballroom, have contributed to a new overall project cost estimate of $2.5 billion, up from $2.4 billion.

“At every point of our constantly evolving cleanup process, when a decision needed to be made, we went with the option that delivered the best quality and most beautiful outcome,” Robert DeSalvio, president of Encore Boston Harbor, said in a statement.

Said Elizabeth Turnbull Henry, president of the Environmental League of Massachusetts: “For decades, this river and sediment have been toxic and unwelcoming to people and nature. With the cleanup complete, we expect to see local communities, plants and wildlife flourish again.”