2005-01-31_REVISION - M1977208 (2)

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Attachment 2 -Point by Point Response to Adequacy Letters Page 2 of 4 ~\ VyC `~Sr ~~k ~ ~\ ~ C` With respect to the off-site Dakota well (also known as the Hall well), Cemex proposes to ,~N u~t,~pr~- remove this from the sampling plan because we believe no threat to the groundwater in this ~0 ,-D formation exists as described in the hydrogeologic analysis and MYRGT model. The proposed S' detection well will serve to verify this analysis. Adequacy Item No. 5: Well Sampling Frequency The detection well shall be sampled quarterly for at least one year for the proposed analytes. After one year of data is available, Cemex would like to review the analyte list and sample frequency with the Division prior to requesting a possible technical revision. Adequacy Item No. 6: A-Pit and C-Pit Sampling Frequency Cemex proposes to sample C-Pit for the proposed analytes quarterly as source monitoring. C-Pit will monitor C-Pit for one year before requesting a reduction in sampling frequency or a o reduction in the list of analytes through a technical revision if warranted. Cemex proposes to eliminate A-Pit as a sampling point due to the absence of hydraulic connection with C-Pit and the relatively impermeable nature of the intervening bedrock. Cemex believes that C-Pit water poses no threat to A-Pit water quality and therefore no threat to the wildlife that may use A-Pit. Adequacy Item No. 7: On-going Presence of Water in C-Pit Cemex proposes to reduce pH and selenium levels in C-pit by continuing to pump the water out until the pond reaches its minimum depth and steady-state size based on the limitations of the submersible pump. A sump pump has failed in the past due to clogging with sediment and is not a practical solution to further reducing the volume of water in C-pit. Cemex does not want or need to maintain water in C-pit for operational use and cannot commit to zero standing water in C-Pit as a practical matter. However, Cemex will monitor C-Pit water and maintain it in accordance with the applicable water quality standards. Cemex proposes to revisit this issue no later than December 2005 when the pond is predicted to be at its lowest practical level. At this time water treatment (as proposed in TR-OS) or other impact mitigation will be proposed, if required, through a Technical Revision. The Division has asked how Cemex plans to keep the water in C-pit from contacting the ever- ~ increasing amount of CKD entering the pit over time. Cemex believes that monitoring and \~~ maintaining the accumulated water in C-Pit below applicable water quality standards will W provide sufficient protection to wildlife and environment. These performance-based standards provide the Division with a defined and quantitative means to measure Cemex's compliance. As such, Cemex does not believe that a detailed management plan is necessary to ensure compliance. Adequacy Item No. 8: Siened Maps Our revised map has been signed and stamped by a qualified professional as requested. This map is enclosed with this submittal.