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(6) The City does not intend to remove the monitoring wells referenced on page 18 of the <br />application. The City uses these to monitor performance of the groundwater drain and soil- <br />bentonite wall. <br />II. DIVISION OF RECLAMATION, MINING, AND SAFETY (DBMS) RESPONSES <br />(1) Dam stability and/or foundation seepage <br />Rule 5.10.1.2 of Rules and Regulations for Dam Safety and Dam Construction states: <br />Borrow areas shall be located at least 200 feet from either toe of the dam. The <br />dimension of this limit may be reduced using engineering analyses indicating <br />that the reduced dimension will not negatively impact dam stability and/or <br />foundation seepage. <br />Division Comment: The applicant has provided an engineering study that demonstrates to the <br />satisfaction of the Division that mining activities will not adversely impact the dam or related <br />structures. <br />(2) Impacts of dewatering. <br />Division Comment: The applicant has stated that no dewatering will occur. Therefore, <br />concerns stemming from dewatering activities are unfounded and the issue has been addressed <br />to the Division's satisfaction. <br />(3) Inert material containing asphalt or other contaminants. <br />Division Comment <br />Rule 1.1(20) of the Construction Materials Rules and Regulations defines asphalt as inert fill. <br />For other materials that may be backfilled in the pit during reclamation, applicant has provided <br />an affidavit stating that any backfilled material will be inert. <br />(4) and (5) Hydraulic conductivity of inert material less than surrounding area. <br />Division Comment <br />Because it will not be possible to predict the hydraulic conductivity of the backfilled material <br />until after backfilling has been completed, the Division recommends that ground water levels at <br />the site be monitored by the Operator during mining and for a period of two years following <br />completion of backfill and other reclamation activities. Monitoring wells owned by the City of <br />Thornton are already in place at locations outside of the permit boundary that can provide the <br />necessary data, and the City of Thornton is encouraged to provide the Operator access to the