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- ,,i <br />tailing is unlikely" suggest to us that the DBMS has not reviewed the extensive geotechnical laboratory analysis we <br />have presented (see the appendix of Exhibit C, TRI Environmental's and Advanced Terra Testing's reports). <br />Nevertheless, Venture Resources seeks to offer another design element compromise to further assure more rapid and <br />complete long term dewatering and drainage. A system of 4" perforated pipe with a geotextile filter sock has been <br />proposed to be incorporated into the Tailings Impoundment as a more active drainage element. This is above and <br />beyond the more passive drainage achieved by the geocomposite filtering liner layer that rests between the proposed <br />HDPE liner and tailings interface (as already submitted in the last technical revision as required by the DRMS from <br />the First Adequacy Review of February 16th). See revised Exhibit C attached for complete details. <br />DRMS Statement in Review Item #3: <br />"Analysis of stability of the proposed geosynthetics interfaces indicates that the geosynthetics are not the limiting <br />factor for impoundment stability. <br />"The DRMS stability analyses do not consider the potential for liquefaction of the proposed impoundment during an <br />earthquake, which maybe the proposal's most significant limitation. DRMS is further concerned that revegetation <br />of the steep, south facing impoundment out-slopes will be severely limited by the proposed 1. 5H. 1 V slopes (refer to <br />Rule 63.4(1)(b) ... " <br />Venture Resources Response to Review Item #3: <br />The assertion that revegetation will be severely limited on slopes steeper than 2H:1 V can be readily disproved by <br />simply observing the natural mountain environment and the revegetation of embankments all along our highway <br />system done by CDOT. <br />Rule 3.1.5(9) states: Maximum slopes and slope combinations shall be compatible with the <br />configuration of the surrounding conditions and selected land use. In all cases where a lake or <br />pond is produced as a portion of the Reclamation Plan, all slopes, ..., shall be no steeper than a <br />ratio of 2:1... " <br />Rule 6.3.4(1)(b) Exhibit D - Reclamation Plan states: "speck the maximum gradient of reclaimed <br />slopes ... If the applicant proposes slopes steeper than 3:1, the Operator/Applicant must include a <br />justification that supports steeper slopes for the proposed post mining land use, and demonstrates <br />compliance with the applicable performance standards of Section 3.1. " <br />Our reading of Rule 3.1.5(9) and 6.3.4(1)(b) does not preclude slopes steeper than 2:1 for the reclamation of a pond <br />or 3:1 for other reclamation. No pond is proposed for final site reclamation. No excavated slopes are proposed <br />other than for construction of the tailing dam. These areas will have tailings deposited. <br />The geotechnical evaluation shows the slopes will be stable. The proposed reclamation plan will result in a site <br />resistant to wind and water erosion. The only comment from the NRCS was to the seed mix for the site and did not <br />question the reclaimability of the site based on the proposed plan or its long term erosional stability. Given the small <br />area to be reclaimed on an annual basis (the largest face area to be reclaimed in a phase, is Bench #4 at over 74 <br />months ... consisting of approximately .84 acres.) reclamation will not preclude hand and/or small equipment <br />reclamation. It will not be necessary for large reclamation equipment to have access to the site and operate on steep <br />slopes. <br />During our last meeting on November 8t' the DRMS concurred, in light of the above discussion, that the <br />reclaimability of the proposed 1.5H:1 V slope will not be as much of a challenge as previously thought. <br />The potential for liquefaction of this proposed Tailings Impoundment during an earthquake has such a slight risk of <br />occurring; such that, when balanced against the very limited hazard potentials to life and property resulting from <br />such an event at the proposed project location, formulating a rigorous engineering design is extreme. Seismic <br />stability analysis has already demonstrated (see Item #1) the enhanced stability by incorporating Synteen geogrid. <br />Additional dewatering methods have been prescribed using "French drains" (see Item #2). Refer to the discussion <br />Page 4 of 5