2004-08-19_REVISION - M2000158 - Laserfiche WebLink

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According to information in the file, the closest offsite surface well is owned by Mr. Ptasnik and is located approximately 1,700 feet east of the Longhorn Lake azea. Kathy Hazdin's well is located approximately 4,750 feet southeast of the Shazkey's Lake, Bruce Rippe's property is located 7,920 feet southeast of the closest slurry wall and Kristi Platt's home is located approximately 6,125 feet southeast of the closest slurry wall. The Western Mutual Ditch is located between the slurry wall and the wells to the east, and will act as a water barrier between the mining operation and the well. A preliminary groundwater evaluation prepazed by GEI Consultants, Inc. concludes that groundwater levels aze expected to rise 4 feet along the south side of Shazkey's Lake. Platte Sand & Gravel will install a surface ditch along the south side of Shazkey's Lake to mitigate impacts from the rise in the groundwater level. In addition, Platte Sand & Gravel will insta114 monitoring wells between the river and the lined azeas, monitor the existing well in the Bluff Lake area and will monitor wells that were proposed in the original rechazge plan to determine pre and post lining water table elevations. Monitoring data will be collected monthly until one year after the fast slurry wall as been built, and quarterly after that. Groundwater information will be correlated with the river flow by obtaining stream flow numbers from a local gaging station. Platte Sand & Gravel will include ground water monitoring data with its annual report to the Division. In the event there is a significant drop (2 feet or more) in the water table caused by the shiny wall liner, a rechazge ditch will be installed along the west side of the liner and irrigation water will be diverted to it to rechazge the azea aoound the trees. Temrination of the groundwater- monitoring plan will require a revision to the permit. The plan to install a slurry wall at the site should greatly decrease the impacts that would be imposed on the groundwater by dewatering the pit. The Operator still acknowledges that the operation at the site will have some degree of impact on the groundwater in the surrounding azea, with the mounding of water on the south side of Shazkey's Lake. The commitment to monitoring groundwater measurements on a monttily basis should give a fairly accurate picture of what the current conditions and the seasonal variations aze at the site and the surrounding azea. The Division believes that monitoring of water levels at the designated locations will reflect a representative groundwater level and will quickly identify any negative impacts to the goundwater in and around the site as a result of mining activity. The mitigation plan submitted by the Operator in the form of rechazge ditches appears to provide timely, effective action to rectify problems that may arise if the operation impacts groundwater. The continued involvement by DMG including submittal of the data in the annual reclamation reports should serve to protect the interests of the surrounding residents that rely on groundwater. In addition, any termination of the groundwater monitoring plan will be reviewed by the Division in the form of a revision to the permit. For all lakes where slurry wall lining will not occur, Platte Sand & Gravel will install the recharge structure as previously approved and agreed to by Mr. Ptasnik and limit the dewatering pit to 1-acre in size to minimize impacts to adjacent well owners. Platte Sand & Gravel stated in the August 2, 2004 adequacy response that "in the rema;n;ng lake azeas, if not lined, the method of mining and well protection precautions will be followed as committed to in 2001." The Division, however, cannot enforce any private agreements between Platte Sand & Gravel and private individuals. On June 9, 2004, The Office of the State Engineer (OSE) informed the Division that the applicant has obtained a SWSP and well permit from their Office. T1re SWSP allows for dry mining as specified in the DMG amendment application. Reservoir azeas do not need augmentation plans since there is no impact to the groundwater system if water evaporates from a reservoir. However, an augmentation plan will be required for the lakes that aze not lined and aze in contact with groundwater. The Office of the State Engineer has established design and performance standazds for slurry walls. It is the operator's responsibility to install the slurry wall (in this case Platte Sand & Gravel is consulting with a construction company to install the shiny wall). It is the responsibility of the Mined Land Reclamation Boazd to hold sufficient bond to assure that the State's Engineer's performance standazd can be met if the Operator of a pit were to default and the state of Colorado were to reclaim the site with the forfeit bond. Operators are free to design and install the liner or slurry wall with relatively minimal design information, specifications and quality assurance detail in the-. -. permit application under the 100 percent bonding option. The assurance that the pit will be reclaimed to developed water resources is primarily managed through the amount of bond held by the Boazd. The OSE has guidelines that stipulate what criteria must be met for the liner to be approved. The Division will not release the bond until the OSE approves the slurry wall liner construction.