I replumbed from septic tank to city sewer

Besides construction cost (slope adjustment, trench digging, piping, landscaping), there is connection fee (permit). It varies from $k to perhaps $20k. Mine was $12k.  How far is city sewer connection point? 

In your case, decontamination could be really big deal. Some contractors may know people at city so they may get clearance on decontamination work quicker and cheaper than you do it.