No building permit for a new structure or for any addition to or alteration of an existing structure that is subject to site plan approval or is part of a major subdivision in accordance with the provisions of this subsection shall be issued by the Construction Official until the completion of all required site improvements, exclusive of buildings, has been certified to the Construction Official by the Board, and the applicant has secured all other permits required by law; provided, however, that the applicant may, in lieu of completing such improvements prior to the granting of such building permit, file with the Borough Clerk a performance guarantee sufficient in amount to cover the cost of all such improvements or uncompleted portions thereof that involve all public roads, facilities and structures intended to become the property of the Borough of West Long Branch or intended to be maintained by same and in an amount to cover the cost of correcting drainage or erosion problems, including the silting of brooks or watercourses, that may occur if the applicant fails to complete the project. Such performance guarantee shall be in the form of cash, bond or other acceptable security as determined by the governing body. The amount of the performance guarantee shall be fixed by the Board and shall not exceed 120% of the cost of the improvements as estimated by the Borough Engineer.