time and material contract with civil engineers

[Will Brown]

I'm developing a multi-family community from scratch, and hired a local civil engineer firm for site work (grading, erosion control, drainage plan, etc.) design. The design will be used to get city permits. 

It is expected that after we file the permit application, the city will come back with comments for us to revise the plan, and it is unclear how much change they city will want. So, in the contract we signed with the civil engineer, we have a fixed dollar figure for the initial design work leading up to permit application. However, due to the uncertainty of how much the engineer will have to work on the city's comments, our contract with the engineer says the engineer's work to address the city's comments will be on a time and material basis.

A few days ago the city got back to us with their comments regarding our permit application. The engineer told me an engineer will need to work 8 days full time to address all the comments, which seems to be an exaggeration of the work involved. Yet there is nothing I can do about it. It is impractical to change the engineer at this point.

I think this is a pretty common problem, very much like being presented a change order (on a time and material basis) by a General Contractor, except it is much hard to determine the time needed for an engineer to finish his job.

How do you deal with such a situation? I'm asking this both for the situation at hand, and for future reference.

If I can do things all over again, it seems my only choice is still a time and material contract for the engineer to work on the city's comments. Any suggestions?