As soon as next Monday, WSDOT says crews will start filling in the Battery Street Tunnel during the day.

SEATTLE — Crews have begun filling the Battery Street Tunnel, marking another milestone in the demolition of the Alaskan Way Viaduct in Seattle.

Contractors will start filling the tunnel during daytime hours as soon as next Monday, according to the Washington State Department of Transportation.

As workers truck in fill material and compact it, residents can expect vibrations on surface streets and nearby buildings between 7 a.m. and 5:30 p.m. The fill material is concrete rubble that was left over from the viaduct.

The Battery Street Tunnel will be filled in during two phases. First workers will fill in the tunnel about seven feet from its ceiling with viaduct rubble that will be trucked in from the south end or poured through grates above the tunnel. Then low-density cellular concrete will be pumped in from surface vents along Battery Street to finish the job. Mixing that concrete onsite will eliminate 4,000 loads of concrete on surface streets, according to WSDOT.

Demolition of the viaduct, which is expected to last about six months, is now over 30 percent complete, according to WSDOT.

However, waterfront business owners say the state agency told them the demolition is behind schedule by three weeks. The waterfront section of the viaduct was originally scheduled to be completed by June 1 and will now likely be finished in mid- to late June.

Crews are currently demolishing the double-decker portion between Madison Street and north of Spring Street, along with a section east of Victor Steinbruck Park.