Great Lakes Dock & Dredge Corp., the country’s biggest dredging contractor, has agreed to acquire North American Site Developers Inc., the Boston-area demolition contractor, for $35 million in cash and $3 million in debt.

The deal, which has not yet closed, would be financed with new borrowings of about $40 million of debt in the form of high-yield bonds, or senior subordinated notes with an interest rate of 11.25 percent.

NASDI says it had revenue in 2000 of $72.6 million. It is the third largest demolition contractor on ENR’s Top 600 Specialty Contractors, with $44.5 million in 1999 revenue. Its services included salvage, recycling and removal of hazardous materials.

NASDI’ top managers have agreed to continue with the company, according to an announcement of the pending deal filed with the Securities & Exchange Commission April 17. The deal structure includes incentive payments for good performance and non-compete clauses should top managers leave.

Great Lakes Dock & Dredge, which is based in Oak Brook, Ill., had net income in 2000 of $7.3 million on $339.1 million revenue.

Allston, Mass.-based NASDI referred calls to comment to Great Lakes, who’s managers couldn’t be reached for comment.