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<br />evaluations of the raise construction phases of the embankment have further demonstrated <br />that the raises meet or exceed the conservative design criteria. <br />Question 2) If the tailings dam would collapse, what are your plans for such an event? <br />Given the conservative design of the embankment as well as the data gathered during <br />construction, there is simply no legitimate technical basis to support your concern regarding <br />a possible failure of the embankment and thus, such a concern is mere speculation. l3MR] <br />does maintain an approved emergency response plan which would eruure adcyuate <br />notification to all of the appropriate emergency response agencies in [he event of potential <br />environmental health or safety concerns resulting from a tailings embankment collapse. "this <br />plan is a part of the Approved Permit referenced above. (See Technical Revision 21 1 <br />Question 3) Since the tailings dam is located on the Ri[o Seco floodplain, will the tailin~~s be <br />removed? <br />"fhe tailings disposal site is not located on the "Rito Seco floodplain" but rather is located <br />immediately adjacent to a topographic saddle on an ephemeral drainage tributary to Culebra <br />Creek. This location is a substantial distance south of the Rito Seco and its floodplain. The <br />tailings will no[ be removed and will remain at this site following closure and reclamation. <br />Please see Section D.6.2 of the Approved Permit. <br />Question 4) What is [he "life expectancy" of the plastic liner? <br />The liner used at the San Luis facility is an engineered continuous composite liner system <br />which consists of a compacted low permeability soil and a geosynthetic membrane ~~ i[h a <br />drain system and a return pump back system. Thus, the synthetic liner is but one component <br />of the liner system. The design details and specifications of the liner system sire set forth in <br />the Tailings Impoundment Construction Report (July 1991) ofthe Approved Permit. It is <br />important to note [ha[ the thin layer deposition method of tailings deposition at the facility <br />has resulted in a consolidated dewatered tailings facility whose measured perneabilit~ has <br />been demonstrated to range from 1 x 10-` cnm/sec to 4 x 10' cnm/sec, thus crer.ting in effect. <br />a thick layer of impermeable material, and a barrier to water movement through the tailings <br />material. <br />Question ~) How much is the present liner leaking? How can we find out? <br />BMRI has maintained a comprehensive QA/QC program in the course of liner installation <br />at the tailings disposal area. In addition, the company maintains an extensive monitoring <br />program which is adequate to detect any evidence of leakage from the facility. On the basis <br />of all of this data and information collected over the course of construction and operation of <br />the facility, there is no legitimate technical rationale to conclude or even st ggest that the <br />current liner is leaking. All of these results are on file in the DMG's offices in Denver. <br />