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Rocky Mountain Asphalt January 20, 1989 Page 5 Maximum Distance Pounds of Explosive fe t Per Delav 1000 190 2000 760 3000 1700 4-000 3030 5000 4740 These data may be utilized for initial planning purposes to maintain off- property blast vibrations to Barely Perceptible levels. The number of boreholes that can be simultaneously detonated Is a function of the borehole depth, diameter, and stemming. The specification of the criteria for these parameters for use during mining is beyond the scope of this report. It should,alab'Ae''!~' emphasized that the distance versus explosive charge weight values ara baaad~an assumed site constants. It Is recommended that blast vibration monitoring be ~ completed at the beginning of site development to estimate site specific vibration attenuation constants Based on available data, the east property line of the Summit Pit will be about 3200 feet from the nearest cave in the Cave of the winds while the Snyder Quarry is currently about 2000 feet from the Cave of the Winds. If blasting is completed at the Summit Quarry Independently (i.e., not at the same time as the Snyder Quarry), the estimated maximum amount of explosive that could be detonated during a single delay sequence should be limited to about 1950 pounds. Althouels sting at the Summit Pit have not been developed, experienca,itt•~ha~-this mrrount of explosive per delay (1950 pounds) I` s~ probably ~~~ra~er than would normally be used during the mining operation./ If blasts at the Summit Pit and Snyder Quarry are detonated at the same time, the total allowable pounds of explosive per delay must be calculated for each blast. It Is unlikely, however, that the blasting In the two pits will occur at precisely. the same time (I.e. within about 1 second of each other). It Is recommended that the blasts at the two pit should be coordinated on a daily basis i- to eliminate the possibility of simultaneous blasting. Schnabel Engineering