HYDRO30314 - Laserfiche WebLink

Home Browse Search

the hydrologic connection from the West Pit and the Rito Seco has been re- established. We do not believe the "long term monitoring" as described in TR-28 is sufficient given the applicant's characterization of the hydrologic system in TR-26 and in the August 30 Technical Support Document. Reducing the long term monitoring requirement to the wells identified in Section 4.1 of TR-28 is insufficient to allow recognition or quantification of releases to groundwater before they significantly impact surface water. Of the 4 alluvial wells identified, wells M-10 and M-34 are remote from the window. Only well M-19 is in the vicinity of the window as mapped in TR-Z6. As the applicant points out, the alluvial aquifer is heterogeneous. A single monitor well in the vicinity of the window is insufficient to allow characterization of the groundwater discharges. Similar azguments can be made for the maintenance of the current TR-26 monitoring system in the bedrock wells, and the Santa Fe Formation wells. We also recommend that a slurry wall around the West Pit where it is in contact with the Rito Seco alluvium be considered as a BMP. The slurry wall would inhibit alluvial groundwater inflow into the eastern comer of the West Pit, thus keeping clean water clean. In conjunction with, or as a sepazate BMP, BMRI should also evaluate the installation of a reactive subsurface bamer/wall in or just downgradient of the window. The reactive wall would inhibit potential contaminated West Pit groundwater from migrating into the Rito Seco. Response: Issues regazding long-term water quality monitoring of groundwater in the vicinity of the West Pit will be addressed by the DMG. BMRI has developed and implemented a performance monitoring program that provides the information necessary to evaluate, assess, and protect the groundwater quality in the vicinity of the West Pit. The content of the first sentence of the comment submitted by RMC also implicitly endorses the technical merits of the existing TR-026 performance monitoring program. Currently, the results obtained from the performance monitoring program aze submitted monthly to the DMG. BMRI proposes to also submit the montltly results to the CDPHE as part of the CDPS reporting requirement. BMRI and its technical experts concurred with the comments of Mr. Bruce Marshall, Rocky Mountain Consultants, [nc., set forth in a letter dated April 20, 2000, which stated that, in his professional opinion, "issuance of this document is Battle Mountain Resources, lnc. HS/GeoTrnns 1 ~ !u!y 11, 1000