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TABLE 14-1 <br />AIRBLAST LIMITS ~ <br />Lower-Frequency Limit of Measuring <br />System, in Hz ('- 3d6) Maximum Level <br />in d6 <br />0.1 Hz or lower -Flat response 134 peak <br />2 Hz or lower -Flat response 133 peak <br />6 Hz or lower -Flat response 129 peak <br />C -Wei hted, Slow response 105 C <br />SCC will conduct continuous air blast monitoring at the Brian Valora and Gary Valora residences to <br />ensure compliance with airblast limitations. Monitoring at the Gary Valora residence will be <br />conducted, particularly during overburden shots in the northern half of the pit. Monitoring will also be <br />conducted at the closest residence (Brian Valoral. particularly during overburden shots in the southern <br />half of the pit. The measuring systems used shall have an upper-end slat-frequency of at least 200 Hz. <br />Ground Vibration. In the past SCC has utilized the scale distance equation W = (DlDslz to determine <br />the allowable charge weight IWI of explosives to be detonated in any 8-millisecond period. The scaled <br /> <br />distance factors IDs) for distance IDI to structures of 0 to 300 feet, 301 to 5,000 feet, and 5,001 <br />feet and beyond are 50, 55, and 65, respectfully. These are the default scale distances used by <br />CDMG if no supporting studies are available /Ru/e 4.08.4(10/1. Thus seismic monitoring may be for <br />the purpose of complying with the maximum one-inch per second ground vibration limitation. The <br />equation is applied to comply with vibration limitations at the location of any dwelling, public building, <br />school, church, or community or institutional building outside the permit area. Computation of the <br />formula or seismographic information and results will be recorded on the blasting record form <br />(Attachment 14-11 for each blast. <br />On November 29, 2001 SCC conducted a series of three seismographic surveys of blasts for the <br />purpose of acquiring data in order to justify the request for variance from the Scaled Distance Factors <br />of Rule 4.08.41101. The primary purpose of the study was to define a modified scale distance factor <br />under which recommended maximum charge weights per 8-millisecond delay period would not exceed <br />approved peak particle velocities of 1.25 inches per second lips) at 0 to 300 feet, 1.00 fps at 301 to <br />5,000 Teet, or 0.75 fps at greater than 5,000 feet. <br />For the Yoast Mine area, the combined results of the study indicate that blasts designed using a <br />modified scaled distance factor of 28.44 will not exceed approved peak vibration levels at the nearest <br />inhabited residences. However, at the request of the Division, Shot k1 was analyzed independent of <br />Shots #2 and 3 and resulted in a higher scale distance factor of 34.85. Based on the indications and <br />3 Revised 2/02 <br />