Each applicant, prior to receipt of a permit, shall provide the township with an acceptable certificate of insurance indicating that he is insured against claims for damages for personal injury as well as against claims for property damage which may arise from or out of the performance of the work, whether such performance is by himself, his subcontractor or anyone directly or indirectly employed by him. Such insurance shall cover collapse, explosive hazards and underground work by equipment on the street and shall include protection against liability arising from completed operations for a period of time to be determined by the Township Committee. The amount of the insurance shall be prescribed by the township in accordance with the nature of the risk involved; provided, however, that the liability insurance for bodily injury in effect shall not be in an amount less than $250,000 for each person and $500,000 for each accident and for property damages an amount not less than $50,000 with an aggregate of $100,000 for all accidents. Public utilities and authorities may be relieved of the obligation of submitting such certificates if they are insured in accordance with the requirements of this chapter.