The Board of Supervisors shall request an approved performance bond, irrevocable letter of credit, or such other acceptable security as determined by the Board of Supervisors following review by the Township Solicitor, to be furnished and filed with the Township Secretary. An escrow agreement and account approved by the Board of Supervisors as to form and content shall be required in the amount of 110% of the estimated construction costs and engineering for each stage of development. All estimates of cost to be approved by the Township Engineer. Such escrow amount shall accompany the request for final approval of the final development plan to insure completion of all public and private site improvements, streets, roads, parking areas, sewers, utilities, recreation facilities, stormwater management facilities, landscaping, plantings and screening.