To promote the state‘s interest in safe, clean, and efficient management and disposal of solid waste, it is hereby declared to be the policy of the state of New Hampshire that competition and enterprise may be displaced or limited by towns and counties, acting alone or in cooperatives or districts permitted under N.H. Rev. Stat. Chapter 53-A or RSA 53-B, in the exercise of the powers, authorities, and responsibilities granted to them in this chapter as necessary to carry out the purposes of this chapter. The intent of this section is to exempt towns, counties, cooperatives, and districts so exercising such powers, authorities, and responsibilities from any liability therefor under N.H. Rev. Stat. Chapter 356 and under federal antitrust laws.