Unanticipated construction issues may delay slightly the opening of a town hall annex at the old Doc Roberts Tire Co. site.

The total renovation of the historic building at South Main and Clay streets for use as town offices is scheduled for completion Feb. 25.

"And we're still working toward that," project manager and town engineering director Adele Schirmer said.

But Schirmer recently cautioned Blacksburg Town Council that unforeseen construction issues such as weather delays and foundation problems uncovered late in the project could push completion to mid-March.

"There isn't anything stalling the project," Schirmer added. "We're still moving forward, and there is a lot of activity."

But every change to the project -- even a small one -- "is not only a cost impact, but it is also a time impact," Schirmer said.

A previously unidentified underground petroleum storage tank was found and had to be removed. A plume of petroleum contaminated groundwater was also discovered flowing beneath the northwest corner of the building and had to be dealt with.

Now, missing foundation footers and other structural problems uncovered during excavation must be repaired, Schirmer said.

The council is scheduled to hear public comment and likely vote tonight on a $200,000 budget amendment to cover costs related to those unforeseen issues.

The project, including purchase of the property, was originally budgeted at $5.1 million.

When it opens, the building will house the town's planning and engineering departments and is meant to showcase the latest in energy conservation technology and low-impact development.