Section 7A. As used in this section, ''damage to the environment'' shall mean any destruction, damage or impairment, actual or probable, to any of the natural resources of the commonwealth, whether caused by the defendant alone or by the defendant and others acting jointly or severally. Damage to the environment shall include, but not be limited to, air pollution, water pollution, improper sewage disposal, pesticide pollution, excessive noise, improper operation of dumping grounds, impairment and eutrophication of rivers, streams, flood plains, lakes, ponds or other water resources, destruction of seashores, dunes, wetlands, open spaces, natural areas, parks or historic districts or sites. Damage to the environment shall not include any insignificant destruction, damage or impairment to such natural resources.

As used in this section ''person'' shall mean any individual, association, partnership, corporation, company, business organization, trust, estate, the commonwealth or any political subdivision thereof, any administrative agency, public or quasi-public corporation or body, or any other legal entity or its legal representatives, agents or assigns.

The superior court for the county in which damage to the environment is occurring or is about to occur may, upon a civil action in which equitable or declaratory relief is sought in which not less than ten persons domiciled within the commonwealth are joined as plaintiffs, or upon such an action by any political subdivision of the commonwealth, determine whether such damage is occurring or is about to occur and may, before the final determination of the action, restrain the person causing or about to cause such damage; provided, however, that the damage caused or about to be caused by such person constitutes a violation of a statute, ordinance, by-law or regulation the major purpose of which is to prevent or minimize damage to the environment.

No such action shall be taken unless the plaintiffs at least twenty-one days prior to the commencement of such action direct a written notice of such violation or imminent violation by certified mail, to the agency responsible for enforcing said statute, ordinance, by-law or regulation, to the attorney general, and to the person violating or about to violate the same; provided, however, that if the plaintiffs can show that irreparable damage will result unless immediate action is taken the court may waive the foregoing requirement of notice and issue a temporary restraining order forthwith.

It shall be a defense to any action taken pursuant to this section that the defendant is subject to, and in compliance in good faith with, a judicially enforceable administrative pollution abatement schedule or implementation plan the purpose of which is alleviation of damage to the environment complained of, unless the plaintiffs demonstrate that a danger to the public health and safety justifies the court in retaining jurisdiction.

Any action brought pursuant to the authorization contained in this section shall be advanced for speedy trial and shall not be compromised without prior approval of the court.

If there is a finding by the court in favor of the plaintiffs it may assess their costs, including reasonable fees of expert witnesses but not attorney's fees; provided, however, that no such finding shall include damages.

The court may require the plaintiffs to post a surety or cash bond in a sum of not less than five hundred nor more than five thousand dollars to secure the payment of any costs which may be assessed against the plaintiffs in the event that they do not prevail.

Nothing contained in this section shall be construed so as to impair, derogate or diminish any common law or statutory right or remedy which may be available to any person, but the cause of action herein authorized shall be in addition to any such right or remedy.