PORT TOWNSEND — A disintegrating brick wall inside the old City Hall’s façade will cost the city about $50,000, city engineers determined Wednesday.

The repair will be absorbed by a $180,000 contingency fund, part of the larger $5.4 million City Hall earthquake retrofit and renovation project that includes a new annex building.

Workers for Dawson Construction, a Bellingham-based contractor undertaking the project, last month discovered faulty mortar inside the wall.

The old mortar, laid in the 1940s, contained moisture and over time turned to sand, leaving brick held in place only by gravity, workers said.

Only the Water Street inner wall was affected, engineers concluded.

The $50,000 repair cost includes the engineering recommendation, demolition of the plaster around window frames, removing and storing the window frames, and brick repair, said Tom Miller, city on-site representative.