Suffolk Construction is suing a developer for outstanding costs due to the delay of a multifamily project in the South End.

Suffolk alleges that developer BentallGreenOak breached its contract and owes it roughly $10M in damages over construction delays on its 304-unit The Smith No. 99 in the South End, according to a suit filed Tuesday in Suffolk Superior Court.

BGO declined to comment. A Suffolk spokesperson said the company is "extremely proud of this project, and we continue to work closely with the owner to resolve any outstanding issues."

The contractor listed several events during the project that resulted in significant delays and an extension in the contract timeframe. Suffolk cited unusual delays in the delivery of a switchgear, utility delays, delays with the gas connection, design changes to the fire alarm system, the developer's changes to cabinet design and inspection delays.

The lawsuit, first reported by Law360, alleges eight counts, including breach of contract, violation of the implied covenant of good faith and fair dealing, and violation of the Prompt Payment Act.

Suffolk's initial contract was for $144M, according to the suit, but due to approved change orders, it was bumped up to $146M. The developer paid Suffolk $143M with an outstanding balance of $2.5M due left over.

Suffolk went on to say that an additional $7.6M in costs were tacked on due to work associated with delays to construction of the building, and that under the contract BGO was required to pay that out.

The contract was set for a 300K SF, 11-story apartment building that represented the second phase of the developer's project on E. Dedham Street. BGO hired Leggat McCall Properties as its on-site inspector for the project, according to the lawsuit.

The first building at 89 E. Dedham St. opened in 2020, and the second building, located at 99 E. Dedham St., opened last month, according to New England Real Estate Journal. The two buildings total 604 apartments.

UPDATE, JULY 9, 10:10 A.M. ET: This story has been updated with a statement from Suffolk.