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results of the regression analysis of the data from Shot /f1, the Division believes that a modified <br />• Scaled Distance Factor of 35, for distances of 301 feet to 5,000 feet between the structures <br />identified in Rule 4.08.4110) and the nearest blast hole, is appropriate. <br />u <br />Using the Scaled Distance Factor of 35, two new Factors were calculated for peak particle velocities <br />of 1.25 fps and 0.75 fps. The +95% confidence level equation using the data from shot 1 is: PPV = <br />326.4 '/SD/ -r'", where PPV is the Peak Particle Velocity in inches per second, th/e~ y-intercept is <br />326.4, the slope is -1.63, and SD is scaled distance. Scaled distance SD = D - y vv , where D is <br />the distance from the nearest blasthole collar to the seismograph in feet, and W is the charge weight <br />per 8-millisecond delay period in pounds. The formula derived from the Shot #1 data set defines a <br />modified scaled distance of 30.39 for distances from 0 to 300 feet, 34.85 for distances from 301 to <br />5000 feet, and 41.57 Tor distances from 5001 feet and beyond. <br />Therefore, based on the Division's review and comments, SCC requested a variance from the default <br />Scaled Distance Factors of 50. 55 and 65 to Modified Scaled Distance Factors of 31, 35 and 42, <br />respectively. Table 14-2, Modified Scaled Distance Factors - Yoast Mine Area, presents a summary of <br />the requested Modified Scaled Distance Factors. <br />TABLE 14-2 <br />MODIFIED SCALED DISTANCE FACTORS <br />YOAST MINE <br /> Maximum Allowable Peak <br />Distance ID) from the Blasting Particle Velocity IV max) For <br />Site Ground Vibration Modified Scaled-Distance Factor <br />Ifeetl linches/second)' IDslz <br />0 to 300 1.25 31 <br />301 to 5,000 1.00 35 <br />5,001 and beyond 0.75 42 <br />11 Ground velocity shall be measured as the particle velocity. Peak particle velocities shall be <br />recorded in three mutually perpendicular directions from the blasting site. The maximum peak <br />particle velocity shall be the largest of any of the three measurements. <br />21 Applicable to the modified scaled-distance equation derived from data collected by MMC <br />(11/29101). See Attachment 14-3, Yoast Mine Ground Motion Attenuation Study. <br />SCC will conduct continuous ground vibration and air blast monitoring at the Brian Valora and Gary <br />Valora residences to ensure compliance with the Peak Particle Velocity limits of Rule 4.08.4110). <br />Monitoring at the Gary Valora residence will be conducted, particularly during overburden shots in the <br />• northern half of the ph. Monitoring will also be conducted at the closest residence (Brian Valora), <br />particularly during overburden shots in the southern half of the pit. <br />4 flevised 2/02 <br />