Performance guaranties shall be submitted in favor of the Borough of Seaside Heights in an amount not to exceed 120% of the cost of installation for improvements it may deem necessary or appropriate, including streets, grading, pavement, gutters, curbs, sidewalks, streetlighting, shade trees, surveyor' s monuments, water mains, culverts, storm sewers, sanitary sewers or other means of sewage disposal, drainage structures, erosion control and sedimentation control devices, public improvements of open space and, in the case of site plans, other on-site improvements and landscaping. Ten percent of the total performance guaranty shall be in cash, deposited with the Municipal Clerk, and the remaining 110% shall be in a form acceptable to the Municipal Attorney. Such guaranties may be usable at any point by the municipality for the nonperformance of the applicant. Such guaranties shall run for a period of 18 months, subject to extension by the Borough Council for an additional period of 18 months.