Demolition of the Robbins block as part of construction for the new jail and justice center cost slightly more than expected because of a number of obstacles uncovered once work began.

The First Street Northeast stretch, which goes from Second to Third avenues northeast, is being converted into a geothermal well field to heat the new building and cost nearly $123,000 to demolish, according to a report from the county engineer.

The demolition was initially slated to cost roughly $106,000, but ash, asbestos, two abandoned wells and some underground footings were all encountered during demolition.

The county used $1.5 million in city money to acquire properties on the block, demolish them and construct the geothermal well — money the City of Austin agreed to give the county in 2007 as the two sides worked on plans for the jail and justice center.