Laserfiche WebLink
AET �20-04834 - Page 3 of 4 <br />Table 2. Vibration Monitoring Results on December 2, 2004 <br />Secondary Rock Crusher <br />Time PPV Frequency Approximate distance to <br />(inls} �X�.) rock c��€t�r (ft) <br />g��l At�'! 0.��43 l� Sta <br />�}-42� A�! �.�4� 1� 1�� <br />�:�� �h{ �.�7�� lG l�Q <br />1�:03 At�! �.��3 1� ��}0 <br />1 1\ <br />Studies of construction related earthborne vibrations have been performed by numerous <br />organizations worldwide. The most commonly accepted study was performedby the United States <br />Bureau of Mines (USBM). This study related earthborne vibration levels and frequencies to the <br />probability of damage to existing structures. A copy of the USBM Alternative Blasting Level <br />Criteria table which was developed from their research is attached. <br />Based upon the Bureau of Mines study, the vibration levels recorded in the Shafer pit as a result <br />of the rock crushing activities are below the safe limits of motion for buildings and residential <br />structures. However, these vibration levels only indicate the conditions at the sampled locations <br />within the Shafer pit. Vibration levels can be affected by several factors, including primary <br />factors such as(1) the media (soil types or bedrock) through which the vibration waves travel, and <br />(2) the rock crushing machinery settings. Therefore, the vibration levels should be expected to <br />vary on a site to site basis. <br />