OGDENSBURG — The cleanup of the former Diamond International paper mill site on the St. Lawrence River has been completed.

City Planning and Development Director J. Justin Woods said Tuesday that he hopes to receive a certificate of completion from the state Department of Environmental Conservation in early 2009. The city contracted with Op-Tech Environmental Services of Massena for the work on the 17-acre property.

"Completing the remedial site work is a critical step in preparing the site for development," Mayor William D. Nelson said in a prepared statement.

Remediation work was expected to be done earlier this year, but the discovery of more concrete vaults, or storage areas, in January at the site extended the cleanup effort by several months.

The overall cleanup cost is about $2.5 million. The city is responsible for covering 10 percent of the overall cost, or about $250,000. The state's Environmental Restoration Program covers the remainder.

The cleanup included the treatment of more than 2 million gallons of wastewater in two clarifiers, then the removal of the clarifiers and underground chests contained within a concrete vault.

The work also solidified the sludge in an emergency holding lagoon with concrete, then capped the lagoon, similar to a landfill. A fence was erected around the lagoon to prevent public access to the area. More than 5,000 tons of contaminated soil also was removed from the site.

"We appreciate the city's efforts to redevelop the site and look forward to it being returned to productive economic use," said Peter S. Ouderkirk, a DEC environmental engineer who oversaw the cleanup.

Engineering firm Barton & Loguidice, Syracuse, has overseen the remediation effort for the city. The firm will submit a report to DEC summarizing the cleanup efforts and recommend no further action. DEC will issue a final report outlining the development restrictions of the property after a 45-day comment period.

The property held a paper mill from 1921 to 1987. The state Department of Environmental Conservation and the U.S. Environmental Protection Agency identified numerous contaminants on the site.

The former Diamond International property is one of the cornerstones of Ogdensburg's waterfront redevelopment efforts.

The city recently selected American Communities Inc., Jacksonville, Ore., to redevelop the waterfront property. The land could be transformed into a mix of town houses, apartments and commercial space. Both parties are working on a predevelopment agreement for the property, City Manager Arthur J. Sciorra said.