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iii iiiiiiiiiiiu iii 999 STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Department of Natural Resources 1 J13 Sherman SL, Room 215 Denver, Colorado 80203 Iii Phone 130J) 86fi-3567 II FAX (303) HJ2-R I06 DEPARTMENT OF NATURAL RESOURCES DATE: June 19, 1997 Roy Romer envernnr James 5 Lochhead TO• Jim Pendleton r.e~~~~°e D~~e~~nr Michael H Long FROM: Susan Burgmaier Division Diredn~ RE: Bowie No. 2 Mine (C-96-083) During my inspection of the Bowie No. 2 Mine earlier this week, I became aware of some possible geotechnical concerns. David Berry suggested i document those concerns for you, so that you could decide whether additional investigation on our part is warranted. A site representative for the contractor that is constructing the road and facilities (Lazry Whitt) stated that groundwa[erhad been intercepteda[ the road fill located a[ S[a[ion 64+00. Mr. Whitt informed me that a fabric wrapped core drain had been installed, and that a culvert had been placed at the base of the fill [o help drain the core. David Jenkel, an associate at J. Stover & Associates, mentioned that the water which drains from the fill "disappears somewhere in the rock", that he hasn't seen where it eventually drains. I asked them if the water had been anticipated when the designs were being developed. They told me that it must have been anticipated, because the core drain was in the plan. Reviewing the plan, 1 did not find a plan for a core drain. The recommendation from M-K and Maxim, where groundwater is discussed, is that if groundwater is encountered, a qualified person should assess the situation and develop any necessary modifications to [he construction plan. 1 am no[ sure if this happened, but it did not appear [hat it did. Until the inspection, [ am not aware [hat DMG was notified of the groundwater occurrence. During the inspection I also became awaze that the large slide located on the eas[em/northeastemhillside above the portals moved considerably in January or February of this year. David Berry was not aware of this, so I thought you might not be either. Joe Dudash, during an inspection in May, was concerned that the embankment for Pond C was compacted against a remnant concrete wall. [ looked at it this week, and have the same concern. I[ does not appear that the concrete wall shows up in any of the design drawings, which would suggest it was not figured into the stability demonstrations. [ am not certain that there has been a geo[echnical engineer present during construction. Basil Bear told me [hat son3eone has been doing compaction tests, but I was not introduced to or made aware of any such person.