The final price tag was about $68 million, or more than double the $30 million previously estimated by the Las Vegas company.
Besides cleaning the 33-acre site in Everett, the company also cleaned up the Mystic River over 18 months.
Wynn says the higher costs come from "increased quality measures" as well as the addition of restaurants and other design changes.
The casino recently was rebranded Encore Boston Harbor following allegations of sexual misconduct against company founder Steve Wynn. Wynn has denied the allegations.
Wynn says it will spend another $14 million creating a 6-acre harborwalk and park.
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