b. As a condition of certification or recertification, a business firm shall be required to provide the department with evidence of financial responsibility for the performance of services provided pursuant to P.L. 1986, c.102 (C.58:10A-21 et seq.), for the performance of tank testing, tank installation, tank removal, tank closure, or subsurface evaluations for corrective action, closure or corrosivity on unregulated heating oil tanks, and for the cleanup or mitigation of a hazardous substance discharge resulting from the performance of such services. Financial responsibility shall be in an amount to be determined by the department but in no case less than $250,000. Financial responsibility may be in the form of insurance, a surety bond, letter of credit, or other security posted with the department, or self-insurance, as may be prescribed by the department. If the financial responsibility is in the form of insurance, a surety bond, or similar device, the business firm shall promptly notify the department of any cancellation or change in coverage. Financial responsibility in the amount and form required by the department shall be maintained for the term of certification by the business firm. A copy of the certification shall be conspicuously displayed for public review in the business office of a firm engaged in tank testing, tank installation, tank removal, tank closure, or subsurface evaluations for corrective action, closure or corrosivity on unregulated heating oil tanks or engaged in providing services for underground storage tanks at underground storage tank sites. If a firm maintains a business office at more than one location, the certification shall be conspicuously displayed at each location.