Before such a permit is issued, the person shall submit evidence, in the form of a certificate of insurance issued by an insurance company authorized to do business in the State of New York, guaranteeing that the applicant has in full force and effect a policy of public liability insurance, including a specific endorsement covering the liabilities arising from blasting and providing bodily injury coverage of not less than five hundred thousand/one million dollars ($500,000./$1,000,000.) and property damage insurance of not less than five hundred thousand/one million dollars ($500,000./$1,000,000.). Such policy shall also provide to save the town harmless from all claims, actions and proceedings brought by any person, firm or corporation for injury to person or property resulting from or occasioned by such blasting operations. Such policy shall contain the provision that the policy shall not be canceled, terminated, modified or changed by the company unless thirty (30) days' prior written notice is sent to the town by certified mail. No permit shall be valid unless such insurance is in full force and effect.