2002-07-26_PERMIT FILE - M2002052 (5)

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Jul•25. 2002 3~b4PM TUTTLE APPLEGATE No•6651 P. 3/12 The aaelytical Aaethods and assumptions are discussod in the attaclpoaart. Although the wozst- case scenario of pumping the entire area of the pit comimtoualy suggests that the dewateriag area o£ lailuence will extend eppreodmately 1,800 feet from the pit boundary, local aqui~r r+acharge and the proposed operating conditions are a~cipsud to reduce this radius significantly. It is estimated that over vne year of comuruous pumping would be required to influerrce an area 1,800 feet from the pit boundary. Auer only two no~ombs of dtwateriisg, as proposed by the applicant, it is estimated that dewaterin~g affaxs wiU extend less than 1,000 fat from the pit boundary. ]Dieing the ten moAthv when the pit is not being dewatered, it is expected that groundwater levels wO1 recover to pre~pumpiag conditions. Therefore, the applicam does not mtticipete dewatering operations at the site to significantly affect the hydrologic balance of the aire~ted lend and surrnuading area or impact the water rights of adjacent well owrtera. However, during dewatering at the site, groundwater levels in the iroatodiate vicinaty are expected to drop. If water levels are dropping in adjacett wells, due to dewateriag at the 'Faun Rivers Mwe, such that well owners' historic water pzoduction may be injured, the applicant will begin to implemem one or more of the following measures. However, if the well has not been put to beneficial use prior to mining, the applicant shaild have no respoasibt7ity to provide mdroigation. 1. Use existing groundwater lakes on the site to recharge the alluvium during mine dewatairrg such that groundwater levels are maimdaed at waves that do sot impact existing wells. 2. Modify e~asting walls to operate under lower groundwater conditions. This would include radrilJittg existing walls to deoper depths or lowering the pampa. All work would be done at the appliceats expe-uz with the exception of replacbog equipment that was oorrfunckional prior to seising. 3. If existing wells cannot be repaired, the apptic~at will drill a new well for the owner to replace the damaged well. The new well wr71 produce water of the same quantity and quality to support the historic use. Additionally, the applicam does sot anticipate that the listed reaervonr will affect alhrviai groundwater elevations up or down gradient of the site. However, to detect and mtpgrte potential impacts to the alluvial groundwater elevation due to murir~g operations or reclamation activities, the applicant will monitor groundwater levels. Growdwster lakes currently exist up gradient and down gradient of the proposed mining operation. Water levels in the lakes will be monitored. AddlBonaAy, adjacont land-awttets are being contacted to motdtor groundwater levels is existing alluvial wells. Groundwater level measurements well be taken on a mombly basis startiosg at a minimum of 3 months prior to exposure of groundwater ai the site and will cominue throughout the arise operation and redamation activities. Data collected prior to mining below the groundwater table will be used to establish baseline groundwater elevations for the site. The groundwater data will be submitted to the lJivision along with other annual reporting requiremeata. Mitigation of potea6al impacts caused by chaaeuog groundwater elevations wr71 be addressed basal upon the apaaSc location and nature of the impact. I£ potential impacts are identified,