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Mr. Timothy A. Cazier <br /> November 19, 2014 <br /> compositional "types" is entering into the MW-7 monitoring well. Trilinear diagrams, ' <br /> also known as Piper diagrams, were developed for select samples that had sufficient <br /> data for plotting. As shown in Figure 5, most groundwater samples plotted within the <br /> calcium plus magnesium, sulfate [Ca+Mg—SO4) type water field shown in the upper <br /> portion of the diamond. However, the MW-7 2008 sample is shifted away from the <br /> primary group of samples towards the sodium plus potassium, bicarbonate [Na+K— <br /> HCO3) type water while the MW-7 2009 sample is clearly a Na+K—HCO3 type water. <br /> These shifts in water composition occurred when depth to groundwater increased. <br /> MW-7 is completed within the Codell Sandstone and the underlying Blue Hill Shale. ' <br /> The MW-7 borehole was completed to a total depth of 70 feet below ground surface <br /> (ft bgs) with the upper 30 feet in the sandstone and the lower 40 feet in the <br /> underlying shale (Figure 6). The borehole was backfilled with silica sand to a depth <br /> of 42 ft bgs. The borehole was cased and a slotted screen interval was completed <br /> from 17 to 42 feet bgs across both the sandstone and shale bedrock. When the ' <br /> depth to groundwater increases at MW-7, the proportion of groundwater that may be <br /> contributed from the shale increases and may result in the observed shifts in <br /> groundwater quality with increased depth to groundwater. No other site groundwater , <br /> monitoring wells intersect the Blue Hill Shale and no other site groundwater <br /> monitoring wells exhibit the wide variability in constituent concentrations observed at <br /> MW-7.The borehole log is included as Attachment 1 to this letter. <br /> 2) Literature Data: <br /> The DRMS has requested that ARCADIS provide some discussion related to the <br /> referenced Report to Congress as to whether or not bio-solids are included in the <br /> characterization of CKD at similar cement plants. The basis for this statement is that , <br /> they indicated sludge samples analyzed for TR-06 suggest the addition of the bio- <br /> solids alter the chemistry of that typical for CKD. <br /> Response: ' <br /> We are not aware of biosolids being used as an admixture for CKD at other cement <br /> plants, and we were not able to obtain any data in that regard. Biosolids were <br /> originally used as a dust control measure. However, biosolids have not been used at <br /> the Portland facility for at least 10 years and represent a small percentage of the total <br /> waste in the facility. As such, it is unlikely that they will have a significant impact on <br /> the overall chemistry of the highly leachable constituents, such as potassium, <br /> sodium, and chloride present in the CKD and be observed in measurements taken <br /> 10 years later. ' <br /> Page: <br /> G ICOMMOMHolom125510105 Correspondenoelresponse to DRMSTR 10 review of Na leflerlsueker revision 20141116\2014 1119 Response to TR 10 review letter do= 4/6 <br />