The municipality may require that the applicant establish and contribute to an Open Space Endowment Fund to cover the continuing costs of maintaining the land (involving activities such as mowing meadows, removing invasive vines, paying insurance premiums and local taxes, etc.), including costs associated with active or passive recreation facilities. Spending from this fund should be restricted to expenditure of interest so that the principal may be preserved. Assuming an annual average interest rate of 2%, the amount designated for the Endowment Fund shall be at least 50 times the estimated annual maintenance costs. Such estimate shall be prepared by an agency, firm, or organization acceptable to the municipality, with such entity having experience in managing conservation land and recreational facilities, and subject to review by the Municipal Solicitor and approved by the municipality. Such fund shall provide the Board of Supervisors with the optional authority to draw monies from the fund if necessary to take corrective measures or to complete basic maintenance that has not been satisfactorily completed. However, the municipality is under no obligation to complete any work on the land if the funds are not withdrawn by the municipality.