A maintenance bond equal to 15% of the cost of the required site improvements shall be required prior to final plat submission. Up to 90% of this total may be either certified check, bank money order or surety bond of a bonding company approved by and at the option of the Township Committee. The remaining 10% shall be certified check or bank money order payable to the Township. In the event of default, the ten-percent cash fund shall be first applied to complete the requirements, and the cash, certified check, or surety bond shall thereafter be resorted to, if necessary. The Municipal Engineer's certification that the principal has satisfactorily installed the improvements or has defaulted shall be the basis for Township Committee's action which accepts or rejects the improvements, withholds approval, or may extend the time allowed for installation of the improvements. As a condition or as part of any such extension, the amount of any performance guarantee shall be increased or reduced, as the case may be, to an amount not to exceed 120% of the cost of the installation as determined as of the time of the passage of the resolution.