2014-11-25_REVISION - M1979191 (22)

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approximate a water table occurring at about 5 -10 feet below grade at these locations. River boundaries were assigned along the Poudre River and Greeley Canal with head boundaries slightly lower than surrounding land elevations. The Poudre River head boundary ranged from 4788 to 4815 from north to south. The Greeley Canal head boundary ranged from 4792 at the eastern model boundary, to 4811 where it connects with the Poudre River. 1.2.3 Model Results Discussion Ditullio: Computed baseline water table elevations ranged from 4805 to 4811 with southerly flow. Observed elevations ranged from 4802 to 4814 (Ref. 1) with measurements indicating_ southerly flow with some localized easterly flow toward Greeley Canal. The model is shows localized flow away from Greeley Canal (i.e. losing stream). ream). Groundwater flow toward the site is conservative for predicting the effects of a liner, because a source of water toward the liner would result in the prediction of higher mounding_ Veldman: Model- calculated baseline water table elevations ranged from 4797 to 4805 with southerly flow. Measured elevations ranged from 4782.9 to 4801.8 (Ref. 2) with elevations suggesting a southerly flow direction. The measured water table near the pond at Veldman (elev. 4782.9 at well TH -7 ) is appreciably lower than calculated in the model. The lower water table may be at least partially associated with the pond at Veldman where the following may be occurring groundwater loss to make up for excavated solids volume; evaporation; and dewatering. No groundwater elevation data is available downgradient to confirm the natural water table gradient. However, pond effects appear likely. The regional topographic grade is about 0.2-0.25% dipping south. The local gradient at Veldman using the TH -1 measurement is 0.5 %. In the predictive model with liner, the predicted change in water level should be interpreted as relative to conditions with no water loss effects initiallv. 1.3 Groundwater Monitoring and Mitigation Plan 1.1.11.3.1 Purpose This Groundwater Monitoring and Mitigation plan has been developed in support of Martin Marietta Materials (MM) Permit Amendment Application to the Colorado Division of Reclamation Mining and Safety (DRMS) M- 1979 -191 112 Permit. The 112 Permit Amendments is being submitted to revise the reclamation plan to Developed Water Storage and to revise the Permit Boundary for the Three Bells Property. This Plan addressed the actions developed by MM that would be implemented should adverse groundwater conditions develop during site reclamation as lined below grade reservoirs. 1.3.2 Background The Three Bells Mine is owned by River Bluffs Ventures, LLC and operated by MM. The mine property is located approximately one half mile north and three miles west of Windsor, Colorado, in Larimer County. The Affected Land is located in Township 6 North, Range 68 West of the 6`h Principle Meridian, in Sections 11, 12, and 13.