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• ~~ established maximum peak particle velocities (PPV) for structures at various distances from blast sites. The OSMRE determined that ground vibrations exceeding the maximum PPV could cause damage to certain structures. While setting ground motion standards, the OSMRE also established Ds constants for various distances. If the distance from the blast site [o a structure is known, then the maximum charge weight (without exceeding the maximum allowed PPV) can be calculated. In the Supplementary Data (Items 1 & 2) submittal, [he operator provided a list of all the structures within 6,500 feet of the proposed quarry area. Except for a railroad bridge, the nearest structure (State Park facilities) is ?,750 feet. Maximum charge weight (using the scaled distance formula) for this particular structure is 2,500 pounds per 8 ms delay. This is predicted to produce a PPV of 1.0 inch per second (ips) which is the maximum allowed PPV (per OSMRE standards). The operator proposes to use 480 pounds of explosives per 8 ms delay and have predicted a PPV of 0.07 ips at this structure. Since the maximum allowed PPV is ].0 ips the projected ground vibration should not cause any damage to this structure. The operator provided a list of predicted PPV's for the four closest structures on page 6 using 480 pounds of explosives per 8 ms delay as the maximum charge weight. As noted, all the predicted PPV's are well below the maximum allowed PPV so the proposed blasting activities should not have an adverse affect on these structures. Blasting generates two other conditions that can cause structural damage. Flyrock can cause serious damage to structures if the rock is of any significant size. However, except for train traffic on the rail line loop, all of the nearby structures are too far away from the blast site to be concerned with. The operator should restrict all train traffic on the loop during blasting operations. Air overpressure (airblast) from blasting activities can cause damage to window panes if enough energy is generated by the blast (or if unfavorable atmospheric conditions exist). The OSMRE states that certain structures exhibit some disturbance (window pane rattling) at 134 decibles (dBL) and that efforts should be made to try to keep airblast levels to 110 dBL (or less) in order to reduce annoyance and complaints as much as possible. Airblast limits are se[ a[ 134 dBL by the OSMRE. Unfavorable atmospheric conditions that can present problems are; 1) low cloud levels, 2) temperature inversion, 3) strong winds, 4) surface temperature and 5) calm conditions during overcast days. I don'[ believe the Division should restrict the operator from blasting during these unfavorable atmospheric conditions unless the Division receives complaints about the airblasts. The important thing is that the operator must collect and record all of the pertinent data during each blast, including accurate weather data, so the Division can determine if a problem exists at the site in the event a complaint is submitted. Where allowed, the operator completed pre-blast surveys at several nearby structures. The observed existing structural damage was photographed and recorded. These documents can be found in Item 2 of the Supplementary Data file. In conclusion, the operator has complied with Rule 6.5 by submitting sufficient data, and engineering analyses, to demonstrate to the Division's satisfaction that the proposed quarry highwall configuration should not be adversely affected by slope failure and that the proposed blasting activities will no[ adversely affect off-site areas.