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Jerry Schnabel, Bob Stabo <br /> July 11, 2016 <br /> Page 4 <br /> from 2 gallons per minute to 0.2 gallons per minute as a result of the earthquake. Research <br /> regarding this alleged well failure did not identify any information detailing the occurrence. We <br /> specifically researched whether or not any replacement well permits were issued by the State <br /> Engineer's Office for the areas adjacent to the proposed quarry around the time of the earthquake, <br /> and there were none. We did confirm that a magnitude 2.5 earthquake occurred in Westcliff in <br /> 2008. <br /> Based on the USGS earthquake information, within the past 8 years, there have been three <br /> additional earthquakes reported from the same approximate Westcliff area that were all higher <br /> magnitude than the 2.5 magnitude earthquake cited by in the public comments. To the best of our <br /> knowledge and based on our research,there have been no additional well failures associated with <br /> these larger earthquake events. <br /> Earthquakes and the resulting seismic waves associated with earthquakes function differently than <br /> the vibrations resulting from blasting. Earthquake magnitude and frequency are capable of <br /> impacting ground water aquifers under certain conditions and at certain distances. However, the <br /> frequencies generated by blasting and the maximum particle velocity limitations required by the <br /> State will limit the vibrations of the blasting to levels at distance from the mine such that aquifer <br /> fracturing or damage will not occur. Accordingly, there is little potential for the aquifer outside <br /> the mine to be damaged or fractured by the mining activities within the proposed mine.l <br /> Ground Water Contamination <br /> Comment: Many of the public comments focused on the potential for contamination of the local <br /> ground water aquifers citing information that indicates a connection between the surface and <br /> ground water and existing water quality issues with total dissolved solids, lead, calcium carbonate, <br /> uranium, other heavy metals and radiological parameter concerns. The comments also indicate <br /> that water high in suspended solids is sometimes noticed in wells after large precipitation events. <br /> Response: First, it is necessary to establish the mechanisms that can result in unfavorable water <br /> quality produced from wells. Summarized below are the general mechanisms that may result in <br /> water quality problems. <br /> 1. Natural minerals in ground water — Ground water may contain dissolved minerals as a <br /> result of ground water flowing through the rock formations and slowly interacting with <br /> rock formations and soils over periods of time. <br /> 2. Suspended solids pumped from wells after precipitation events - If natural conduits exist <br /> between an aquifer system or a well and surface water systems, then suspended solids in <br /> surface water can flow through fractures in rock formations relatively directly to water <br /> supply wells. When turbid water exists in streams or in drainages at the surface, for <br /> example after rain events,this turbid water can flow to wells where it might be pumped by <br /> the well to a water tap. This can also occur if grout seals in wells were not successfully <br /> installed at the time of construction. <br /> 'Rorke,A.J.,"Blasting Impact Assessment for the proposed New Largo Colliery based on New Largo Mine Plan 6", <br /> November 2011. <br /> , www.bb � t c og. <br />