The Town Board shall review and audit all such vouchers and shall approve payment of only such consultant charges as are reasonable in amount and necessarily incurred by the Town in connection with the review and consideration of applications. A charge or part thereof is reasonable in amount if it bears a reasonable relationship to the average charge by consultants to the Town for services performed in connection with the review of a similar application. In auditing the vouchers, the Town Board may take into consideration the size, type and number of buildings to be constructed, the topography of the site at issue, environmental conditions at such site, the infrastructure proposed in the application and any special conditions the Town Board may deem relevant. A charge or part thereof is necessarily incurred if it was charged by the consultant for a service which was rendered in order to protect or promote the health, safety or other vital interests of the residents of the Town and protect public or private property from damage.