2008-01-15_PERMIT FILE - M2007044 (2)

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alternatives for Division review and approval. A minimum of three Atterberg Limit tests must be conducted on representative soil samples during construction of the ore pad. The Operator may not use the pad for ore storage until the compaction is complete and the Division has reviewed and accepted the soil test results. Also, the Operator must periodically inspect the pad for indications of desiccation and freeze/thaw effects that will increase permeability. If these effects are observed, the upper twelve inches of soil must be reworked, moisture conditioned as needed, and compacted. The Operator must report on ore pad inspections and any reworking of the pad soil liner in each annual reclamation report. The proposed ore pad is similar in design to the ore pads that have been traditionally permitted and used on the Colorado Plateau. The proposed liner consisted of run-of- mine waste and was not intended to be totally impermeable (i.e., hydraulic conductivity of about 1 x 10"5 cm/s); rather, we had proposed to over-excavate the pad liner during closure to recover any radionuclides and metals that had seeped into the pad over time. Since there is almost no hydraulic head on the ore pad liner, the amount of material that had to be excavated at closure was minimal (i.e., estimated to be about 18 inches). This approach had been tentatively approved by DBMS staff during earlier meetings on the project. Energy Fuels does not object to upgrading the liner for the ore pad, provided that we are permitted to store ore for longer than the 6 month period allowed by DBMS for more traditional ore pads. The Whirlwind Mine area is not located near a good source of clay that could be used to build a less permeable ore pad. Therefore, we are including an alternate design using a geosynthetic liner for your consideration. The design was prepared by Golder Associates and is included as Attachment F to this response letter. The specifications included with this design include 3rd-party quality assurance (QA) inspections and testing. QA reports will be submitted to DBMS for review prior to pad loading. 12) Placement of the soil liner should have a temperature limitation. No frozen soil liner materials shall be used as liner fill. Preparation of the native area should be a major consideration prior to placement of the soil liner fill. It must be reasonably smooth and void of large rocks and objects. The Golder pad design, included as Attachment F, provides engineering specifications for pad construction including placement of fill material and sub-base preparation. 13) Surface Water Management: The Applicant proposes a number of permanent surface water diversion structures in the mining and reclamation plans. These structures have been sized to safely pass flows from a 100 year, 24-hour precipitation event. Since the diversions are to remain following reclamation, the Division requires that they be sized to pass flows resulting from the probable maximum precipitation event. 1:~~~rgy 1"uel5 R~5<~~u~c~s C;c>r~c>raticm =1~ lnic:m I~cnrle~acd, ~t~ite (i0t} 10 1..~1a~~~t~c~cl, C~~) $f}12~ 1'hc~i~~: 303-t)74-2~14t)