Quincy's Conservation Commission has denied the city of Boston's request for a permit to move forward with the project to rebuild the Long Island Bridge. The group voted unanimously to reject the permit request in their meeting Wednesday.

This is just the latest flashpoint in a public standoff between Mayor Marty Walsh and the city of Quincy over rebuilding the bridge to Long Island in Boston Harbor. Mayor Walsh wants to build a recovery campus there for people recovering from addiction, but the bridge would connect to the mainland in Quincy.

Walsh announced the project before discussing it with Mayor Thomas Koch.

Now, a structural engineer hired by Quincy has said Walsh's plan to rebuild the bridge on top of 1940s-era concrete piers is “extremely unrealistic.”

“Basically these piers would need to be rebuilt in their entirety,” says Chris Walker, chief of staff for Koch. “The Conservation Commission asked the city of Boston to go back and do the additional testing as requested by our experts. The city of Boston refused. Based upon that, the Conservation Commission voted it down.”

"[Boston] has conducted extensive testing of the structural integrity of the bridge to Long Island that has informed the current design proposal for the bridge, and also rehabilitates and repairs its existing infrastructure," city officials said in a statement to WGBH News. "It should be noted that bridge piers of this age and older are regularly kept in service and rehabilitated for reuse around the country.”

Koch's office expects Boston to appeal the decision to the state Department of Environmental Protection, according to his chief of staff.

“Our position is clear,” Walker says. “The city of Boston needs to pursue alternative means of access to Long Island. They continue to push forward with plans for a bridge that is ill-conceived, ill-thought out, and not in the best interests of the public or anyone that either city intends to serve by this bridge.”