2015-08-20_REVISION - M2002004 (3)

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August 20, 2015 Mr. Tyler O'Donnell Colorado Division of Reclamation, Mining and Safety Department of Natural Resources 1313 Sherman Street Room 215 Denver, CO 80203 OGCC Rio Grande RECEIVED AUG 0 2 2015 DIVISION OF RECLAMATION MINING AND SAFETY RE: Technical Revision to Mining Permit No. M-2002-004 R -off Follow-up Response to Question on August 17, 2015 - Proposed Beneficial Re -Use of a Portion of Kiln Feed Material from the Main Kiln Baghouse in Quarry Area for Reclamation Backfill Purposes GCC Rio Grande, Inc. - Pueblo Cement Plant and Limestone Quarry Dear Mr. O'Donnell: Per your conversation with Brian Mensinger on August 17th, 2015, GCC Rio Grande, Inc. (GCC) has prepared this letter to address your question regarding the depth at which the raw material from the main kiln baghouse is placed during reclamation. This question stemmed from GCC's response to questions submitted to Colorado Division of Reclamation Mining and Safety (DRMS) on August 12, 2015. In the division's letter dated May 27, 2015, DRMS asked the following question based on review of GCC's Technical Revision No. 5 (TR -05) submittal: 12) The approved post -mining land use for the affected lands is rangeland. The sampling results submitted indicate that there are high concentrations of heavy metals in the dust Will the vegetative species in the approved seed mix absorb or uptake the heavy metals located in the backfilled dust? If plant absorption or uptake of the heavy metals occurs, will bioaccumulation of heavy metals pose a danger to grazing livestock? Could high levels of heavy metals in the soil impair revegetation efforts? GCC provided the following explanation in its August 11, 2015 response: The reclaimed areas will be covered with a separation of approximately one foot of overburden or topsoil used with reclamation thus preventing the vegetation from being able to uptake heavy metals. As a result, this will also prevent bioaccumulation. Providing one foot of topsoil ensures that re - vegetation efforts are not impeded. Also, the results of the MEP tests show that the heavy metals are stable and do not leach thus are unlikely to be available for plant absorption or uptake. At the request of DRMS, GCC proposes an alternate depth of the raw material from the main baghouse in quarry reclamation, which is as follows: Upon completion of reclamation, the raw material from the main baghouse will be three feet beneath the surface, which is equal to one foot of topsoil and two feet of overburden. This measure provides additional assurance that vegetation will not uptake heavy metals and/or minimize bioaccumulation.