N.H. Rev. Stat. § 12-E:6

I. Upon approval of the mining and closure plans and prior to the issuance of a permit, the operator shall file with the commissioner proof of adequate financial assurances, as determined and required by the commissioner, payable to the state of New Hampshire with sureties or other security satisfactory to the commissioner to adequately secure compliance with this chapter upon default by the operator. The amount provided shall equal at least 110 percent of the costs necessary to achieve the requirements set forth in the approved closure plan. The commissioner shall have the authority to adjust after the issuance of the permit the financial assurances required commensurate with any change in information or circumstances, including but not limited to the size and impact of the permitted mining operation or a modification of planned closure activities. In no case shall the financial assurances provided be less than $10,000 per acre of permitted site. The commissioners of the department of natural and cultural resources and the department of environmental services shall review the adequacy of the financial assurances provided at the time of permit renewal or when an amendment to the existing permit is requested, and at such other times as deemed appropriate. II. All proceeds of forfeited financial assurance or other security shall be expended by the commissioner for closure of the affected site. Upon issuance of a certification in writing, signed by the commissioner, that all closure activities have been satisfactorily completed, the remainder of any financial assurance shall revert to the operator or other party as designated in the financial assurance plan. III. The commissioner shall establish a schedule, as is appropriate, for the partial release of the financial assurances as portions of closure activities are completed. All financial assurances provided, or portions thereof as detailed in the schedule, shall be released when closure of the affected site, or portions thereof, have been completed by the operator to the satisfaction of the commissioner and in no case sooner than 3 years from its filing. IV. A financial assurance plan for prospecting may be required by the commissioner whenever he or she determines possible injury to the land or water may occur and such activity does not occur on a permitted site. V. All approvals, adjustments, expenditures, and releases of financial assurances as provided for in this section shall require the concurrence of the commissioner of the department of environmental services.