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Page 7 of 8 <br />Mr. Tyler O'Donnell <br />TR -05 Response to Questions <br />Samples were analyzed for total heavy metals and MEP according to EPA 1320. The analysis results have been <br />included in Attachment A. Note that the material total metals are at orders of magnitude greater than the results <br />of the MEP process, which is similar to the TCLP results previously provided. <br />11) In order for the Division to approve the placement of the kiln baghouse dust into the quarry with no hydrologic <br />barrier, (such a HDPE liner and/or a compacted clay liner) the Division will require an extensive groundwater <br />monitoring plan with both upgradient and downgradient wells. Please provide a groundwater monitoring plan <br />which contains at a minimum the following information such as, background data, well locations, well depths, <br />well logs, geologic information, the screened intervals on every well, well construction methods and well <br />completion methods. <br />Based on the hydrogeologic setting in the vicinity of the quarry, evidence with the prior groundwater wells <br />drilled in 2009 through 2013, a lack of groundwater presence is demonstrated. Many of the wells originally <br />drilled were de -commissioned due to being dry for an extended period. GCC would like to review the <br />groundwater monitoring plan as a separate discussion with the Division. GCC believes that additional time and <br />effort is required based on the background of groundwater monitoring activities and observance of dry wells <br />that have occurred at the site. This will allow GCC to install the dust shuttling system as required to comply will <br />Portland Cement Maximum Achievable Control Technology regulations (MACT) standards, which is in effect <br />September 9th, 2015. <br />12) The approved post -mining land use for the affected lands in rangeland. The sampling results submitted indicate <br />that there are high concentrations of heavy metals in the dust Will the vegetative species in the approved seed <br />mix absorb or uptake the heavy metals located in the backfilled dust? If plant absorption or uptake of the heavy <br />metals occurs, will bioaccumulations of heavy metals pose a danger to grazing livestock? Could High levels of <br />heavy metals in the soil impair revegetation efforts? <br />The reclaimed areas will be covered with a separation of approximately one foot of overburden or topsoil used <br />with reclamation thus preventing the vegetation from being able to uptake heavy metals. As a result, this will <br />also prevent bioaccumulation. Providing one foot of topsoil ensures that revegetation efforts are not impeded. <br />Also, the results of the MEP tests show that the heavy metals are stable and do not leach thus are unlikely to be <br />available for plant absorption or uptake. <br />13) The Division is currently reviewing the total metals and TCGP data with the Colorado Division of Heath and <br />Environment's Hazardous Materials and Waste Management Division (HMWMD). The Division will follow-up <br />with any comments and concerns received form HMWMD. <br />The only concern addressed by HMWMD was the presence of Radium -226 and 228 in historic groundwater <br />monitoring results. Based on review of the results, groundwater samples were collected from three shallow <br />alluvial monitoring wells (MW002, MW003, and MW004) in the vicinity of the St. Charles River. The alluvial <br />wells represent downgradient conditions with respect to the Cement Plant operations. A monitoring well <br />(MWO01A) was also completed in the Codell Sandstone which represents upgradient conditions. Results of the <br />radiochemistry analyses show that gross alpha activities exceed the Colorado groundwater standard of 15 <br />picoCuries/Liter (pCi/L) in wells MW002, MW003, MW004, and Dup-01 (MW002 duplicate sample). The 15 <br />pCi/L standard excludes activities due to radon and uranium. Radon and uranium activities were not measured. <br />