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' VIBRATECH® The seismographs monitored in histogram mode, which recorded the air overpressure and peak ' ground movement at either five second or five minute irrtervals. The seismographs were not set-up in time to monitor the blast on July 10, 2003. Also, due to the seismographs internal memories becoming filled with non-blast related events, corrupted data files and battery failure, there is no ' data for the following locations and dates: • Davis Residence (Site #1) July 14, 2003 through July 26, 2003 (Instrument failed due to battery failure) and from September 29, 2003 through October 14, 2003. • NE Comer (Site #3) September 6, 2003 through October 14, 2003. DISCUSSION ' THE SEISMOGRAPH The Vibra-Tech seismographs are four-channel recorders, which directly measure particle velocity ' in three mutually perpendiculaz directions. "Particle Velocity" is defined as "how fast a particle is moved by passing waves, measured in inches per second". The fourth channel is employed for monitoring air overpressures. On site peak levels aze displayed at the conclusion of each event with ' the event data being internally stored. The data stored in the seismograph's internal memory are later processed into analog printouts. ' Analog representations of this data aze included in the attachments at the end of this report. ' The first ground vibration trace is labeled "transverse" and represents horizontal motion at right angles to the vibration source. The second represents "vertical" particle velocity and is so labeled. The third is labeled "longitudinal" and represents horizontal motion along a direct tine between the ' recorder and the energy source. Calibration information is supplied for each recording. AIR EFFECTS ' AIRBLAST OVERPRESSURE VIBRATION CRITERIA from USBMRI-8485 ' The USBM has set forth airblast overpressure limits in its Report of Investigation RI-84851 "Structure Response and Damage Produced by Airblasts from Surface Mining". Although the air vibrations produced by production blasting aze typically referred to as noise levels, the ' USBM report recognizes that airblast overpressures with frequencies below the threshold of human hearing (infrasonic) are capable of producing structural response. The most common example of infrasonic air vibrations that may produce structural response is wind rattling a window. Accordingly, the USBM has recommended limits based upon the frequency range of the recording system (instrument). The maximum allowable airblast limit increases as the range of the recording system expands further below the audible frequency range of the human ear. ' Siskind, David et al, Structural Resnonse and Damage Produced by Airblast from Surface ' Mining, U.S. Bureau of Mines, RI 8485, 1980.