If the Planning Board determines it is necessary to ensure that all items on the site plan that are needed to provide for adequate traffic flow, utilities, and other similar infrastructure items, are constructed in accordance with the approved final site plan and any other pertinent specifications and requirements, no building permit shall be issued for a project with an approved final site plan until the applicant has furnished to the Town Engineer an irrevocable letter of credit in an amount to be recommended by the Town Engineer and approved by the Planning Board to ensure such construction. In determining whether to require such a letter, the Planning Board shall find that such infrastructure is so integral to the project that its construction must occur in order to provide for a safe and useful environment for the community and the occupants and users of the project. The Planning Board may, in its discretion, accept in lieu of a letter of credit other evidence or promise of completion of required facilities for the site if it determines that such other evidence adequately ensures such completion. Nothing in this section shall alter any other requirement for letters of credit related to construction of facilities intended to be dedicated to the Town.