Neumann Brothers Inc., of Des Moines, submitted a project base bid for $6.19 million. One alternate option in the bid could deduct $30,000, should supervisors want to sacrifice the copper gutters.

The single bid may force supervisors to go back to the drawing board as it comes in at least $500,000 higher than previous county estimates for the project.

Older estimates on the project, in an extensive report completed January 2019, pegged the project’s cost between $3 and $4 million.

Toward the end of 2019, supervisors unanimously decided to move forward with an option for the project that they thought would cost an estimated $5 million. The option selected includes a partial replacement of the clock tower that will keep the intact pieces of the old green patina sheathing and restore the roof’s skylight.

The other three options included taking no action on repairs, removing the clock tower and repairing the skylight for an estimated cost of $2.8 million, or replacing the clock tower with a completely new skin at an estimate of $10 million. Supervisors previously solicited and received feedback through public input sessions.

The sheathing’s extensive weathering over 118 years contributed to the need for action. The project has been a top priority for supervisors in long-term planning, with hopes to have renovations completed by the end of this year.

A key part of the restoration would include installation of a plastic membrane to act as a water barrier between the copper and wood, leaving most levels of the tower dry. The top level of the tower is open to the air, so that the bell can ring. The water barrier will be designed so that water can flow back outside, preventing rotting of the wooden structure underneath.

Supervisors are scheduled to discuss and potentially approve the bid at Tuesday’s regular meeting.