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<br />Hydrodynamics Incomorated <br />Sixth comment; regarding Mn at RS-3. (Supplements! comment). Station RS-3 is <br />upgradient of BMRI activities and upgradient of prior heap leaching activities that <br />occurred in the RS-3 drainage. Seasonal and annual variation are expected in most <br />drainages, so the change, if any, seems incidental. Alternatively, it appears that <br />changes in labs or detection levels or both may appear in the raw data as a shift in <br />background concentrations. Regardless. the RS-3 station is a background station; its <br />underlying geology is more representative of lower Rito Seco geology than RS-1. <br />9. Eighth comment; regarding reclamation soil and sulfate and Mn contamination. <br />Reclamation soils are those that were in place prior to mining. While it is reasonable <br />to assume that rainwater may flush constituents from disturbed soils in concentrations <br />exceeding pre-disturbance conditions -for any disturbed soil situation anywhere - <br />thiscondition is expected to be temporary. <br />The Reviewer should know that, for several reasons, TSS monitoring presents <br />significant challenges in this setting. Firstly, there is no room for an upstream <br />monitoring station where the geology is similar to the disturbed portion of the Rito <br />Seco; the upstream-most disturbed area begins at a significant change in geology and <br />is coincident with a significant change in erosion patterns. The upstream station is <br />floored by Precambrian rocks with thin soils and relatively dense forest cover <br />whereas the disturbed area is floored by loose alluvial soils of the Santa Fe Formation <br />that erode significantly due to road disturbances. While the mine-caused erosion is <br />significantly checked by erosion prevention structures, the county road hosts very few <br />such structures, so assigning the relative contributions from each source would be a <br />challenge. <br />Continuous monitoring is not considered necessary; periodic monitoring meets all the <br />requisite requirements. <br />Peoples Alternative Enemy Services. <br />10. Re: "Failure to Mee[ Water Quality Requirements." <br />The Reviewer rephrased the Operator's presentation on how risk assessment relates to <br />water standards in a misleading way. The Reviewer stated as follows: "If BMRI's <br />view was correct, a discharger would be free to violate stream standards as long as <br />their consultants did a study saying uses were protected." This interpretation does not <br />appear anywhere in the TR-26 application. <br />The "Screening Level Risk Assessment" (SERA) was of considerable use uo the <br />Division. It identified contaminants, receptors and pa[h~.vays, and provided the <br />Division with essential information [o determine whether [o initiate a rapid response a <br />more studied response. The Reviewer should understand that standards are <br />