Section 6. For any of the purposes set forth in this chapter, and for the purposes of developing or assisting in the development of any regulation pursuant to this chapter, or conducting any study mandated by Congress or by the General Court, any owner or operator of an underground storage tank shall upon request of the department, the head of the fire department, and their personnel or authorized agents, furnish information relating to such tanks, their associated equipment and their contents, conduct monitoring or testing, and permit the department, the head of the fire department, and their personnel or authorized agents, to have access to, and to copy all records relating to, such tanks. For any of the purposes set forth in section four, and for the purposes of developing or assisting in the development of any regulation pursuant to this chapter, or conducting any study mandated by Congress or by the General Court, the department, the head of the fire department, and their personnel or authorized agents, are authorized (1) to enter at reasonable times any establishment or other place where an underground storage tank is located; and (2) to inspect and obtain samples from any person of any regulated substance contained in such tank; and (3) to conduct monitoring or testing of the tanks, associated equipment, contents, or surrounding soils, air, surface water or ground water. Each such inspection shall be commenced and completed with reasonable promptness.