Laserfiche WebLink
.'' 1 <br />III IIIIIIIIIIIIIIII <br />STATE OF COLOR~U <br />Roy Romer, Gove <br />DEPARTMENT OF NATURAL RESOURCES <br />MINED LAND RECLAMATION DIVISION <br />FRED R. BANTA, Director <br />DATE: May 10, 1989 <br />T0: Matt Hayes <br />FROM: Jim Pendleton <br />RE: Blue Ribbo oal Co ny - NOY C-89-008 Abatement Plan <br />(Permit #C-81-047) <br />I have reviewed the abatement plan submitted for Blue Ribbon Coal Company by <br />their consultant, James Stover, P.E.. NOV C-81-047 was issued to Blue Ribbon <br />Coal Company fora surficial slump which occurred in March, 1989 on the face <br />of their reclaimed mine bench. The NOY required that the operator submit an <br />acceptable plan for abatement of the environmental risk. <br />Mr. Stover's presentation is clear and unambiguous. He concludes that the <br />1989 slump was caused by saturation of the upper 4 feet of cover material by <br />infiltration of melting snow waters. He discusses observations supporting his <br />conclusion. He also effectively discounts alternative hypotheses suggesting <br />deep seated instability within the bench caused by infiltration of waters <br />ponding on the top surface of the reclaimed bench. He includes observations <br />from the monitoring facilities installed at the mine bench and from <br />excavations completed following the failure. I concur with Mr. Stover's <br />conclusion that the 1989 slump is surficial and caused by infiltrating snow <br />melt. <br />Mr. Stover also proposes a repair plan for the soil slump. He proposes to <br />reclaim the 7989 slump analogously to the 1988 slump at the same site. He <br />documents that the 1988 repair is performing acceptably, with which my <br />observations concur. Finally, he proposes the installation of two additional <br />piezometers adjacent to the reclaimed slump to attempt to document in future <br />years whether saturation is a surficial or deeper seated phenomena. <br />The only aspect of Mr. Stover's proposal with which I would disagree is his <br />proposed design of the second additional piezometer "P-6". He proposes to <br />install P-5, sealing the upper 8 feet with Bentonite and opening the <br />piezometer to the deeper 8 to 20 foot depth interval. This will provide <br />monitoring of deeper seated waters. He then proposes to seal P-6 at 2 feet in <br />depth and leave it open from 2 to 20 feet in depth. I am concerned that this <br />will not allow isolation of the near surface waters from the deeper fluids. I <br />suggest that Mr. Stover amend Piezometer P-6 to install it to a total depth of <br />8 feet with a seal at 2 feet be]ow the surface, and that he ]eave the <br />215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 7e1. (303) 866-3567 <br />