2005-01-28_REVISION - M1999120 (2)

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Construction Materials Rules and Regulations to which they pertain. ISSUES WITHIN THE JURISDICTION OF THE DIVISION AND BOARD AND RAISED DURING THE INITIAL PUBLIC COMMENT PERIOD 3.1.6 Water -General Requirements 1. On November 1, 2004, the Division received a letter from Ross Bachofer stating the following concern: " I am on a water well that is vulnerable to contamination from drawing too much water or from surface contamination getting into the 35-60' level of water I use from. And of course, pumping the water table down to the point that my well goes dry or at least has periods where it is dry because of too much drawdown and not enough recovery time." Division of Minerals and Geology (DMG) Responses- The questions raised by the above comments aze related to Section 3.1.6 in the Construction Materials Rules and Regulations, specifically: "Disturbances to the prevailing hydrologic balance of the affected land and of the surrounding azea and to the quantity or quality of water in surface and groundwater systems both during and after the mining operation and during reclamation shall be minimized..." On January 4, 2005, Banks and Gesso, LLC, on behalf of L.G. Everist, Inc., submitted responses to the first adequacy review letter related to this amendment application. In these responses, the Operator has committed to installation of slurry walls azound each phase prior to commencement of mining and dewatering activities in the pit. Included in the fast adequacy response materials was a groundwater report composed by Wright Water Engineers (WWE), Inc. The report includes maps depicting the predicted impacts to groundwater levels in the vicinity of the proposed amendment azea, which aze the result of the presence of slurry walls and the expanded activities at the site. The predictions are based on observations related to neazby gravel mining operations and on a MODFLOW groundwater model (a program used by the USGS for groundwater modeling) that incorporates what appeaz to be conservative, realistic assumptions for the azea in question. The results of the model indicate that potential impacts to groundwater levels in the vicinity of the operation consist o£ • A 5-foot drop in groundwater level north of the proposed expansion azea extending approximately 500 feet north of the site. • A gradual decrease in this groundwater level drop to approximately 1-foot 5,000 feet northeast of the site. • A 2-foot drop in groundwater level east of the site decreasing to a 1-foot drop approximately 1,000 feet east of the site.