“We agree with the district court that the doctrine of primary jurisdiction does not foreclose plaintiffs’ FCA suit alleging Davis-Bacon Act violations where, as here, the government was not aware of the conduct at issue until after Wall filed his complaint, and thus did not deliberately bypass administrative procedures; the determination whether Circle C acted with the requisite intent to defraud the government in violation of the FCA does not necessitate technical, agency specific expertise; and the regulations explicitly provide that the falsification of payroll certifications may subject the contractor to civil prosecution under the FCA. Plaintiffs allege violations of the FCA under a false certification theory; this is not a dispute over how a particular type of work should be classified for purposes of wage determinations. Accordingly, deferral to  DOL was not warranted, and the district court properly declined to refer the case to the DOL pursuant to the primary jurisdiction doctrine…[W]e affirm the district court’s judgment with regard to liability, but reverse the award of damages and remand for a recalculation of the damages and further proceedings.”