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Wild Horse Dams and Reservoir West Test Quarry DRMS 111 Application <br /> between holes. Blasts will be designed to limit ground vibration and flyrock at neighboring points of concern as <br /> identified by ERO Resources (Reference Section 2.4). <br /> United States Bureau of Mines (USBM) standards limit the peak particle velocity(PPV)to 2 inches per second (ips) <br /> at the location of the nearest structure. Structure in this standard refers to any area of potential concern, not only <br /> physical structures. While it is difficult to estimate ground vibration without an empirical model (actual levels are <br /> heavily dependent on local geologic conditions), it is expected that the PPV at a 200-ft distance will not be more <br /> than 2 ips. A vibration monitoring system will be implemented for the duration of the test quarry operations. The <br /> drilling and blasting program will commence with the blast located the farthest practical distance away from the <br /> known avoidance areas in order to gauge the site-specific ground vibration levels. Based on the first data collected <br /> at the site, an empirical model will be developed to more precisely estimate ground vibration levels. <br /> Flyrock will be minimized through use of'stemming' blast hole (filling upper limits of blast hole with inert material <br /> such as sand rather than explosives) which will minimize surface material fractures (generating larger-graded <br /> material) as well as minimize flyrock distance.Additional protection of the land against flyrock may be performed <br /> using granular ballast material placed over the delays,though stemming will be the preferred measure.Additional <br /> control measures including hole diameter, powder factor, and timing delay can also be used for mitigation. <br /> The following drilling and blasting sequence is planned: <br /> • Surface surveying of blast area to determine appropriate drilling and blasting elevations; <br /> • Laying out of drill hole patterns; <br /> • Drilling of blast holes; <br /> • Loading of blast holes with explosives, and the placement of stemming materials; <br /> • Connection and checking of the initiation system; <br /> • Clearing of blast area and surrounding safe zone of equipment and personnel as required; <br /> • Verification of a clear blast zone, pre-blast warning signals; <br /> • Blast initiation; <br /> • Recording of blast information including total amount of explosives used, maximum charge of each <br /> hole, cubic yards blasted, blast vibration, and noise monitoring; and, <br /> • Post-blast inspection: Blaster in Charge verifies initiation of all explosives and that blast is safe for <br /> excavation. <br /> Tetra Tech May 2024 18 <br />